hrsg.pdf

Project Title

Client

Consultant

Contractor

CHKD.DESCRIPTION

ISSUE FOR INFORMATION

REV

000

CONVERSION OF QURAYYAH OPEN CYCLE POWERPLANT TO COMBINED CYCLE POWER PLANT

PROJECT C

APPD.CERT.

09-Sep-11

DATE

J.S.KimC.R.KimB.H.Park

Document Title

CREATED BY: CHECKED BY:

DATE STARTED: DATE COMPLETED:

OPR'G. DEPT.: ENG. DEPT.:

DOC. NO. REV. NO.

QURAYYAH SAUDI ARABIA

JOB ORDER NO.

3DT

THIS DOCUMENT IS NOT TO BE USED FORCONSTRUCTION OR FOR ORDERING

MATERIAL UNTIL CERTIFIED AND DATED

JOB NO.

1-0923053.01

30621127

APPROVAL/CERTIFICATION INFORMATION

O&M MANUAL FOR HRSG

000 00019 000

PROJECT SUBDIVISION DOCUMENT TYPE CODE DOCUMENT NUMBER REV. NO.

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Qurayyah CCPP HRSG

Chapter 1.0 General Doc.No :XXXX Rev. 000

1.0 GENERAL

1.1 Purpose

1.2 Introduction

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Qurayyah CCPP HRSG

Chapter 1.0 General Doc.No :XXXX Rev. 000

1.1 Purpose

This technical document provides the necessary instruction for the operation and maintenance of the Heat Recovery Steam Generators (HRSG), installed in the Qurayyah Add-on Combined Cycle Power Plant 30 & 40, Saudi Arabia.

1.2 Introduction

The triple pressure heat recovery steam generator (HRSG) with reheater based on the natural circulation principle is located downstream of combustion gas turbine for use in a combined cycle power plant which is installed in the Qurayyah Add-on Combined Cycle Power Plant 30 & 40, Saudi Arabia.

The Qurayyah plant consists of five (5) blocks and each block consists of three(3)

gas turbine generator units(GT Model GE 7FA), three(3) unfired HRSGs utilizing the exhaust heat of the gas turbine and one(1) steam turbine generator unit (STG).

The gas turbines and associated components have been installed as part of

previous Qurayyah open cycle project. Exhaust gas diverter dampers is provided and able to divert flow to either the bypass stack for open cycle operation, or to the HRSG for combined cycle operation.

Each HRSG operates independently with its own gas turbine and produced steam

to be fed into a common steam header to drive the steam turbine.

The HRSG is unfired, reheat, three (3) pressure levels of high pressure (HP), intermediate pressure (IP) and low pressure (LP), natural circulation and vertical gas flow design. The low pressure drum is provided with feedwater storage function. The integrated deaerator is mounted on the LP drum.

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[텍스트 입력] Qurayyah CCPP HRSG

2.0 General Description Doc.No :xxxxx Rev. -

1 HRSG SYSTEM OVERVIEW This document describes the Heat Recovery Steam Generator (hereafter HRSG) system for the Qurayyah Combined Cycle Power Plant. The Qurayyah plant consists of five (5) blocks and each block consists of three(3) gas turbine generator units(GT), three(3) unfired HRSGs utilizing the exhaust heat of the gas turbine and one(1) steam turbine generator unit (STG). The gas turbines and associated components have been installed as part of previous Qurayyah open cycle project. Exhaust gas diverter dampers is provided and able to divert flow to either the bypass stack for open cycle operation, or to the HRSG for combined cycle operation. Each HRSG operates independently with its own gas turbine and produced steam to be fed into a common steam header to drive the steam turbine. The HRSG is unfired, reheat, three (3) pressure levels of high pressure (HP), intermediate pressure (IP) and low pressure (LP), natural circulation and vertical gas flow design. The low pressure drum is provided with feedwater storage function. The integrated deaerator is mounted on the LP drum. The HRSG is designed to have the following output at Guarantee condition;

Load Case N-1(Guarantee) D-1 (Guarantee)

GT Load 100 % 100 %

Ambient temperature 33 deg.C 33 deg.C

Fuel type Natural Gas Distillate Oil

HP Steam pressure at superheater outlet 132.19 bara 107.92 bara

HP Steam temperature at superheater outlet 567 deg.C 527.7 deg.C

HP Steam flow at superheater outlet 53 kg/s 44.3 kg/s

HRH Steam pressure at reheater outlet 36.34 bara 30.59 bara

HRH Steam temperature at reheater outlet 566 deg.C 523.5 deg.C

HRH Steam flow at reheater outlet 58.6 kg/s 50.7 kg/s

IP Steam pressure at superheater outlet 37.66 bara 31.73 bara

IP Steam temperature at superheater outlet 339.7 deg.C 322.8 deg.C

IP Steam flow at superheater outlet 7.5 kg/s 8.2 kg/s

LP Steam pressure at superheater outlet 6.34 bara 4.04 bara

LP Steam temperature at superheater outlet 252.1 deg.C N.A

LP Steam flow at superheater outlet 6.6 kg/s 0 kg/s

Stack Exhaust Gas temperature 107.2 deg.C 153.7 deg.C

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1.1 High Pressure (HP) system

Reference P&ID ; - P&I Diagram – HRSG H.P Superheater Section [Dwg No. EA-685640] - P&I Diagram – HRSG H.P Econ. & Evap. Section [Dwg No. EA-685642] The high pressure steam generation system generates HP steam of specific quality, which means of correct pressure and temperature, from the thermal energy contained in the Gas turbine exhaust gas. The steam is produced in the HRSG and fed to the HP main steam system. - Heating surface information of HP system;

Component Tube Material Design Pressure

(barg) Design Temperature

(Deg.C)

HP Economizer 1 SA210C 210 371

HP Economizer 2 SA210C 210 371

HP Evaporator SA210C 153 360

HP Superheater 1 SA213-T11 153 451



- Safety valves information of HP system;

Description Tag. No. Set Pressure (barg) Capacity (kg/s)

HP S.H ERV LBA-90-AA-191 145.5 9

HP S.H SV LBA-90-AA-192 146 14.9

HP Drum 1st SV HAD-90-AA-191 153 22.4

HP Drum 2nd SV HAD-90-AA-192 157.6 22.4

HP Economizer SV HAC-90-AA-191 210 19.1

The system fulfils the following object:

Delivers feedwater to the high pressure drum during start-up, shut-down and power operation of the combined-cycle unit.

Shuts off feedwater supply during feedwater control malfunction in order to prevent overfeeding of the HRSG.

Supplies HP steam produced by the HRSG to the HP main steam system during normal operation.

Supplies HP feedwater to the HRSG HP desuperheating system. Maintains and safeguards the HP superheated steam temperature within the allowable main

steam system limit during part load operation at high ambient temperatures.

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HP Feedwater System The HP feedwater line is equipped with a check valve to prevent back-streaming from the HRSG into the feed water pumps. The line can be isolated by a motorized stop valve. The HP feedwater control valve station is located downstream of the HP economizer to prevent steaming of feedwater in the economizer. A relief valve is installed downstream of economizer to prevent overpressure in the economizer if the HP feedwater control valve is closed and HRSG in operation. From the HP feedwater line, the spray water line to the HP desuperheating spray system branch off. The HP desuperheating spray system delivers water into the HP interstage desuperheater located between HP superheater heating surfaces. It can limit the HP steam temperature within the design value during part load or normal operation at high ambient temperature. The Max. spray flow is approximately 8% of the steam flow. HP Steam Generation The high pressure system is located downstream the exhaust gas inlet of the HRSG. The heating surfaces are fabricated mainly from finned tubes. The high pressure system is subdivided into the following sections, listed in the order in which exhaust gas flows through them;

HP Superheater 3/2/1 HP Evaporator HP Economizer 2/1

The HP economizer recovers the remaining heat contained in the exhaust gas at the HP evaporator outlet. The HP evaporator generates steam through a natural circulation loop from and to the HP drum. The HP superheater heats the saturated steam from HP drum temperature to superheated steam. The HP superheater and the HP economizer are cross counter flow heat exchangers and the HP evaporator flow is cross to the exhaust gas flow. The HRSG is of vertical design. The feedwater is fed by the HP/IP feedwater pumps from the LP drum to the HP economizers, where it is heated up to economizer outlet temperature and then delivered to the HP drum. Water is fed from the HP drum through downcomers to the inlet header of the HP evaporator. Water partly evaporates in the HP evaporator and the water/steam mixture is fed via natural convection in the tube risers from the outlet header back to the HP drum. The connection piping between the outlet header and drum is distributed uniformly over the length of the drum.

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The HP drum has the following functions:

ensure good mixing of feedwater and HP Drum water reserve a water required for the circulation system allow water expansion during start-up ensure a thorough water and steam separation Deliver saturated steam of specified purity (<0.1% carry over)

The HP drum capacity is selected to ensure safe and stable operation under all normal operating conditions. The HP drum is installed outside of the casing thus is not heated by exhaust gas. The separation of water and steam is achieved by means of water/steam separation system (Two stage separation system, baffle assisted separator as a primary and chevron type of dryer as a secondary separator), which restricts carryover of water to the superheater within the limits. Two safety valves are installed on the HP drum to protect the system against over pressure. The vent piping from the drum safety valves is routed into the silencer to limit noise level. Sampling connections are provided in the system for sampling of HP drum water (taken off from the continuous blowdown line) and saturated steam (taken off from the saturated steam piping) from the HP drum during operation. Connection for chemical dosing is installed at the HP drum. The intermittent blowdown line from the HP drum to the HRSG blowdown system is equipped with a motorized valve. The continuous blowdown line from the HP drum to the HRSG blowdown system is equipped with a motorized stop valve and a manual blowdown valve. Saturated steam flows from the HP drum through connecting piping to the HP superheater. The HP superheater is divided into three parts. A desuperheater is located between the HP superheater2 &3 heating surfaces to maintain the HP steam temperature within the design value during part load operation at high ambient temperature. (For the detail of set point, refer to the item no.8 in Clause 5.) HP Main steam Piping system The HP main steam piping system receives HP steam from the HRSG and transfers it to the HP steam header.

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Drain station is provided in the system to allow system drainage and warm-up particularly during start-up. A motorized start up venting system is provided in the piping to remove the non-condensable gas like an air during start-up. A safety valve is installed to protect the system against over pressure. In addition, electrically assisted relief valve (ERV) is provided in the HP main steam piping. The vent piping from the steam line safety valve, ERV and start up vent valve is routed into the silencer to limit noise level. Sampling connection is provided in the system for HP steam sampling during operation. The HP steam line is equipped with a check valve to prevent back-streaming from another HRSG. The line equipped with motorized main and small stop valve, which is used to isolate or connect to the common steam header.

1.2 Intermediate Pressure (IP) system

Reference P&ID ; - P&I Diagram – HRSG I.P Section [Dwg No. EA-685563] - P&I Diagram – HRSG Reheater Section [Dwg No. EA-685641] The intermediate pressure steam generation system generates IP steam of specific quality, which means of correct pressure and temperature, from the thermal energy contained in the GT exhaust gas. The IP steam is produced in the HRSG and fed to the Cold reheat steam system and mixed with the exhaust steam from the ST. The superheated steam produced by the reheat system is fed to the hot reheat steam header. - Heating surface information of IP system;



(Deg.C)

IP Economizer SA192 75 292

IP Evaporator SA192 45.48 264

IP Superheater SA192 45.48 358

Reheater 1 SA213-T11 45 532

Reheater 2 SA213-T91 45 595

- Safety valves information of IP system;


Hot Reheat SV LBB-90-AA-191 40.5 9.8

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Cold Reheat 1st SV LBC-90-AA-191 42.5 27.6

Cold Reheat 2nd SV LBC-90-AA-192 43.8 27.6

IP S.H SV LBA-95-AA-191 43 2.5

IP Drum 1st SV HAD-94-AA-191 45 3.7

IP Drum 2nd SV HAD-94-AA-192 46.4 3.7

IP Economizer SV HAC-94-AA-191 75 1.6

The system fulfils the following object:

Delivers feedwater to the intermediate pressure drum during start-up, shut-down and power operation of the combined-cycle unit.

Feeds superheated IP steam from the HRSG to the cold reheat system Supplies IP feedwater to the HRSG RH desuperheating system. Maintains and safeguards the hot reheat steam temperature within the allowable hot reheat

steam system limit during part load operation at high ambient temperatures. Shuts off feedwater supply during feedwater control malfunction in order to prevent

overfeeding of the HRSG. Passes the exhaust steam of the HP turbine and the steam from the IP superheater via the

reheater section of the HRSG to the hot reheat steam header. IP Feedwater System The IP feedwater line is equipped with a check valve to prevent back-streaming from the HRSG into the feed water pumps. The line can be isolated by a motorized stop valve. The IP feedwater control valve station is located downstream of the IP economizer to prevent steaming of feedwater in the economizer. A relief valve is installed downstream of IP economizer to prevent overpressure in the economizer if the IP feedwater control valve is closed and HRSG in operation. From the IP feedwater line, the spray water line to the RH desuperheating spray system branch off. The RH desuperheating spray system delivers water into the RH interstage desuperheater located between Reheater heating surfaces. It can limit the hot reheat steam temperature within the design value during part load or normal operation at high ambient temperature. The Max. spray flow is approximately 5% of the steam flow. IP Steam Generation The intermediate pressure system is located downstream the exhaust gas inlet of the HRSG behind the HP part. The heating surfaces are fabricated mainly from finned tubes. The

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intermediate pressure system is subdivided into the following sections, listed in the order in which exhaust gas flows through them;

IP Superheater IP Evaporator IP Economizer

The IP economizer recovers the remaining heat contained in the exhaust gas at the IP evaporator outlet. The IP evaporator generates steam through a natural circulation loop from and to the IP drum. The IP superheater heats the saturated steam from IP drum temperature to superheated steam. The IP superheater and the IP economizer are cross counter flow heat exchangers and the IP evaporator flow is cross to the exhaust gas flow. The HRSG is of vertical design. The feedwater is fed by the HP/IP feedwater pumps from the LP drum to the IP economizers, where it is heated up to economizer outlet temperature and then delivered to the IP drum. Water is fed from the IP drum through downcomers to the inlet header of the IP evaporator. Water partly evaporates in the IP evaporator and the water/steam mixture is fed via natural convection in the tube risers from the outlet header back to the IP drum. The connection piping between the outlet header and drum is distributed uniformly over the length of the drum. The IP drum has the following functions:

ensure good mixing of feedwater and IP Drum water reserve a water required for the circulation system allow water expansion during start-up ensure a thorough water and steam separation Deliver saturated steam of specified purity (<0.1% carry over)

The IP drum capacity is selected to ensure safe and stable operation under all normal operating conditions. The IP drum is installed outside of the casing thus is not heated by exhaust gas. The separation of water and steam is achieved by means of water/steam separation system (Two stage separation system, baffle assisted separator as a primary and chevron type of dryer as a secondary separator), which restricts carryover of water to the superheater within the limits. Two safety valves are installed on the IP drum to protect the system against over pressure. The vent piping from the drum safety valves is routed into the silencer to limit noise level. Sampling connections are provided in the system for sampling of IP drum water (taken off from the

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continuous blowdown line) and saturated steam (taken off from the saturated steam piping) from the IP drum during operation. Connection for chemical dosing is installed at the IP drum. The intermittent blowdown line from the IP drum to the HRSG blowdown system is equipped with a motorized valve. The continuous blowdown line from the IP drum to the HRSG blowdown system is equipped with a motorized stop valve and a manual blowdown valve. Saturated steam flows from the IP drum through connecting piping to the IP superheater. IP steam Piping system The IP main steam piping system receives IP steam from the HRSG and transfers it to the Cold reheater piping system. Drain station is provided in the system to allow system drainage and warm-up particularly during start-up. A motorized vent valve is provided in the piping to remove the non-condensable gas like an air during initial start-up. A safety valve is installed to protect the system against over pressure. The vent piping from the steam line safety valve and start up vent valve is routed into the silencer to limit noise level. Sampling connection is provided in the system for IP steam sampling during operation. A pressure control valve is installed in the IP steam piping and used to control the IP system pressure within allowable range during start up and shut down period. The IP steam piping can be isolated by motorized stop valve. A check valve is provided to prevent back streaming from the cold reheat piping system. Reheater system The reheater, which is divided into two parts, is located in high temperature gas zone. During normal plant operation the exhaust steam from the HP turbine section is routed via the reheater of the HRSG to the IP turbine inlet. Before entering the reheat section the HP turbine exhaust steam is mixed with superheated IP steam coming from the IP superheater. The line from the HP-steam bypass is routed to the cold reheat line during bypass operation. Reheater desuperheating spray system deliver water into the reheater desuperehater located between the divided reheater heating surfaces. It limits the steam temperature to the allowable range during part load operation at high ambient temperatures. (For the detail of set point, refer to the item no.12 in Clause 5.)

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Two safety valves are installed upstream and one safety valve downstream of the reheater to protect the system against overpressure. A sampling connection is provided in the downstream of the reheater system for steam sampling during operation. Drain station is provided in the system to allow system drainage and warm-up particularly during start-up. A motorized stop valve and pneumatic control valve in series is provided in start up venting system in the Hot reheat piping to control the steam pressure during start-up. The vent piping from the steam line safety valve and start up vent valve is routed into the separate silencer to limit noise level.

1.3 Low Pressure (LP) system

Reference P&ID ; - P&I Diagram – HRSG L.P Section [Dwg No. EA-685644] - P&I Diagram – HRSG Condensate Preheater Section [Dwg No. EA-685645] - Heating surface information of LP system;



(Deg.C)

Condensate Preheater SA192 40 252

LP Evaporator SA192 10 185

LP Superheater SA192 10 278

- Safety valves information of LP system;


LP S.H SV LBD-90-AA-191 9 1.9

LP Drum 1st SV HAD-97-AA-191 10 2.82

LP Drum 2nd SV HAD-97-AA-192 10.3 2.82

C.P.H SV LCA-91-AA-191 40 15.3

The low pressure steam generation system generates LP steam of specific quality, which means of correct pressure and temperature, from the thermal energy contained in the GT exhaust gas. The steam is produced in the HRSG, supplied to heat the condensate in the deaerator system and fed to the LP steam system. Condensate through the condensate preheater is fed to the

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deaerator where it is heated and deaerated with steam from the LP evaporator. The deaerator is integrated at the top of the LP drum for the deaeration of condensate. The system fulfils the following object:

Delivers condensate to the deaerator and LP drum during start-up, shut-down and power operation of the combined-cycle unit.

Shuts off condensate supply during feedwater control malfunction in order to prevent overfeeding of the HRSG.

Supplies LP steam produced by the HRSG to the LP steam system during normal operation. Reserves and Supplies feedawater to the feedwater pumps Supplies saturated steam from the LP drum to the deaerator for deaeration. Remove non condensable gases like CO2 and oxygen from the condensate during

operation of the plant. Control the temperature of the condensate entering the condensate preheater.

Condensate System The condensate line is equipped with a check valve to prevent back-streaming from the HRSG into the condensate extraction pump. The line can be isolated by a motorized stop valve. The LP drum level control valve is located downstream of the condensate preheater to prevent steaming of condensate in the condensater preheater. A relief valve is installed downstream of condensate preheater to prevent overpressure in the condensate preheater if the LP drum level control valve is closed and HRSG in operation. LP Steam Generation The low pressure system is located downstream the exhaust gas inlet of the HRSG behind the IP part. The heating surfaces are fabricated mainly from finned tubes. The low pressure system is subdivided into the following sections, listed in the order in which exhaust gas flows through them;

LP Superheater LP Evaporator Condensate preheater

The condensate preheater recovers the remaining heat contained in the exhaust gas at the LP evaporator outlet. The LP evaporator generates steam through a natural circulation loop from and to the LP drum. The LP superheater heats the saturated steam from the LP drum temperature to superheated steam.

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The LP superheater and the condensate preheater are cross counter flow heat exchangers and the LP evaporator flow is cross to the exhaust gas flow. The HRSG is of vertical design. The condensate is fed by the condensate extraction pumps to the condensate preheater, where it is heated up to condensate preheater outlet temperature and then delivered to the deaerator. The condensate preheater system is equipped with recirculation system which is used to control the condensate preheater inlet temperature. The condensate preheater recirculation pump recirculates water from the outlet of the condensate preheater to the inlet of the condensate preheater. The temperature control valve, which is located in the recirculation pump discharge line, controls the recirculation flow to maintain the condensate preheater inlet temperature. To prevent less flow operation, below minimum flow of the recirculation pump, the recirculation system control must limit the closure of the temperature control valve when the recirculation pump flow approaches actual min. flow. The condensate preheater system is also equipped with a condensate bypass system. The three-way valve sends condensate water flow to the condensate preheater and/or bypass around the condensate preheater. The three-way valve can be positioned to ; 1. direct all condensate flow to the condensate preheater, 2. direct all condensate flow through the condensate preheater bypass, 3. direct any portion of the flow to either the preheater or the bypass around the condensate

preheater. When the recirculation pumps are all failure, the three-way valve is positioned in the fully-closed position, resulting in all the condensate flow bypassing the condensate preheater so that the HRSG can be continuously operation without shut down. The three-way valve is positioned to route a portion of the condensate flow to the condensate preheater bypass as required to hold a minimum subcooling before entering the deaerator to ensure an optimum deaeration process. At the top of the LP drum, a direct contact spray-tray-type deaerator vessel is provided. A spring loaded spray nozzle is provided for guaranteed operation of deaerating. All condensate through the condensate preheater is fed to the deaerator where it is deaerated and heated by the saturated steam from the LP drum and the resulting air is expelled through the vent line to

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atmosphere. The deaerated condensate falls down through the deaerator downcomer and collected in the LP drum. Water is fed from the LP drum through downcomers to the inlet header of the LP evaporator. Water partly evaporates in the LP evaporator and the water/steam mixture is fed via natural convection in the tube risers from the outlet header back to the LP drum. The connection piping between the outlet header and LP drum is distributed uniformly over the length of the LP drum. The LP drum has the following functions:

ensure good mixing of feedwater and LP Drum water reserve a water required for the circulation system and providing feedwater to the feedwater

pumps allow water expansion during start-up ensure a thorough water and steam separation Deliver saturated steam of specified purity (<0.1% carry over)

The LP drum capacity is selected to ensure safe and stable operation under all normal operating conditions. The LP drum is installed outside of the casing thus is not heated by exhaust gas. The separation of water and steam is achieved by means of water/steam separation system (Two stage separation system, baffle assisted separator as a primary and chevron type of dryer as a secondary separator, which restricts carryover of water to the superheater within the limits. The steam for the heating of the deaerator/LP drum is supplied by various sources. The main source of steam is the LP evaporator. Additionally, the pegging steam is supplied from the IP superheater outlet steam line. This pegging steam operation is required when the LP drum pressure cannot be maintained above floor pressure or drops quickly. Two safety valves are installed on the LP drum to protect the system against over pressure. The vent piping from the drum safety valves is routed into the silencer to limit noise level. Sampling connections are provided in the system for sampling of LP drum water (taken off from the BFP suction line) and saturated steam (taken off from the saturated steam piping) from the LP drum during operation. The suction line is provided from the LP drum to provide feedwater into the feedwater pumps.

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Connections for the min. recirculation and leak off lines from the feedwater pumps are provided on the LP drum. The intermittent blowdown line from the LP drum to the HRSG blowdown system is equipped with a motorized valve. Saturated steam flows from the LP drum through connecting piping to the LP superheater. LP steam Piping system The LP steam piping system receives LP steam from the HRSG and transfers it to the steam header. Drain station is provided in the system to allow system drainage and warm-up particularly during start-up. A safety valve is installed to protect the system against over pressure. A motorized stop valve and pneumatic control valve in series is provided in start up venting system in the LP steam piping to control the steam pressure during start-up. The vent piping from the steam line safety valve and start up vent valve is routed into the separate silencer to limit noise level. Sampling connection is provided in the system for LP steam sampling during operation. The LP steam line is equipped with a check valve to prevent back-streaming from another HRSG. The line equipped with motorized main and small stop valve, which is used to isolate or connect to the common steam header.

1.4 Exhaust Gas system

Reference P&ID ; - P&I Diagram – HRSG Flue Gas Section [Dwg No. EA-685661] The HRSG exhaust gas system comprises the gas tight component of the exhaust gas path with HRSG exhaust gas inlet ducting, HRSG casing and exhaust gas stack. The exhaust gas system also includes the HRSG framework, stiffening elements, heating surface suspension, expansion joints, insulation and instrumentation. The system fulfils the following requirements;

Rooting the exhaust gas from the outlet of the GT exhaust gas system through the HRSG to the HRSG exhaust gas stack during the combined cycle operation.

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The gas turbine exhaust gas flows through the HRSG exhaust gas inlet ducting and the HRSG before being routed to atmosphere via the HRSG exhaust gas stack. The HRSG heating surfaces are divided into the following sections in the direction of the exhaust flow;

HP superheater 3 Reheater 2 HP superheater 2 Rehater 1 HP superheater 1 HP evaporator IP superheater HP economizer 2 IP evaporator LP superheater HP economizer 1 / IP economizer LP evaporator Condensate preheater

The heating surface mainly consist of horizontal finned tubes joined together to form heating surface packages. The tube banks are suspended in the HRSG frame and walls. The HRSG is of vertical design. The cooled exhaust gas, after it leaves the last heating surface (Condensate Preheater), flows through the HRSG exhaust gas stack. A stack damper is provided to reserve a heat in the HRSG casing during shut down period. A stack silencer is provided to limit noise within allowable value.

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- Temperature Profile of Exhaust Gas System;

1.5 HRSG Blowdown system

Reference P&ID ; - P&I Diagram – HRSG Blowdown Tank Section [Dwg No. EA-685646]

The HRSG blowdown system is to collect and discharge excess water from the HP/IP/LP drum in a controlled manner during start-up. Furthermore, water is collected from the steam line and HRSG system located in the HRSG area.

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The blowdown system is designed to collect the process water from drains, continuous and intermittent blowdown. The main purpose of the blowdown system is to receive the discharge of blowdown water in order to control boiler water quality and decrease drum levels. The continuous blowdown is used to control the water quality. The purpose of the intermittent blowdown is lowering drum water levels. - Blowdown Tank Design and Operating Condition; * Design Condition; 3.5 barg, 390 deg.C * Operating Condition; Atmosphere, 100 deg.C The system fulfils the following requirements;

To collect and discharge excess water from the HRSG drums in a controlled manner during start-up.

To collect continuous blowdown from the HRSG HP and IP drums during normal operation. To collect steam/water from the drain of main steam, feedwater systems located in the

HRSG area. To discharge excess water through the intermittent blowdown line. To deliver the vapor in the blowdown tank to the atmosphere through the vent line. To discharge the collected drain water after cooling down to blowdown sump.

The blowdown tank is vertical, cylindrical tank in which drain headers enter tank tangentially above water level. The tank water level is maintained by an internal loop seal of overflow line. A drain line is supplied at the bottom of tank to allow complete drain. A silencer is supplied at exhaust vent line to limit noise level.

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Qurayyah CCPP HRSG

3.0 Description of Component Doc.No :xxxxx Rev. -

3.0 DESCRIPTION OF COMPONENT

3.1 General Description 3.2 Steam Drums for HP, IP and LP System 3.3 HP Superheaters 3.4 Reheaters 3.5 HP Evaporator 3.6 HP Economizers 3.7 IP Superheater 3.8 IP Evaporator 3.9 IP Economizer 3.10 LP Superheater 3.11 LP Evaporator 3.12 Condensate Preheater 3.13 Safety Valve 3.14 Vent Silencer 3.15 Duct and Casing 3.16 Expansion Joints 3.17 Insulation and Lagging 3.18 Access Door 3.19 Gas Bypass Baffle 3.20 Stack 3.21 Stack Silencer 3.22 Support Structures 3.23 Stairs, Platform and Ladders 3.24 Instrumentation and Controls 3.25 Piping 3.26 Attemperator 3.27 Blowdown Tank

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Qurayyah CCPP HRSG

3.0 Description of Component Doc.No :xxxxx Page 1 of 33 Rev. -

3.0 DESCRIPTION OF COMPONENT

3.1 General Description The HRSG is constructed in accordance with ASME Boiler and Pressure Vessel Code, Section 1, Rules for Construction of Power Boilers under the inspection of the ASME authorized inspector. Construction per this code is defined to include, but is not limited to, material selection, design, fabrication, examination, inspection, testing, certification, and stamping. The major features of HRSG are as follows. - Shop assembled pressure parts modules - Horizontal tube arrangement - Vertical gas flow - Top support for pressure parts modules - Direct weld construction for header and tube - Staggered tube arrangement - Cold outer casing - Natural circulation - Noise Control enclosure

Heat Transfer Tube Arrangement

- Tube diameter : 31.8mm, 38.1 mm, 44.5 mm - Tube arrangement : Staggered Only - The longitudinal space : 87 mm (RH section), 79 mm (others) - The transverse space : 92 mm - The assembled HRSG consists of fourteen (14) different heat exchanger

sections from the inlet transition duct to the exit of HRSG. - Each heating surface is composed of multiple layers tube bank of finned tubes. - All finned tubes are attached with serrated or solid fin, which is helical wound

onto the tube under tension. - The very low penetration of attachment weld minimizes any effects on the

physical or chemical characteristics of the tube and/or the fin.

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- Heat transfer surfaces is arranged to allow sufficient expansion and contraction movement of the tubes during startup, shutdown, load transients and normal operation.

- Minimum evaporator circulation ratio is 4 to 1. All evaporators will have downcomers. All superheater, evaporator reheater and economizer feeder headers will include openings for inspection.

- All heat transfer sections, including headers, economizers, reheaters and superheaters is completely drainable.

- Access cavities between modules have a minimum of 900 mm clear space to assure easy maintenance and inspection around finned tube bundle area. Each access cavity has a one (1) flanged 610 x 460 mm access doors.

Casing Design

- Not exposed to high temperature - Not exposed to exhaust gas temperature transient - Shop fabrication of assembly. - Stud bolts are welded to the inside of the outer casing. Insulating blanket is

impaled on the stud bolts. - An oversize washer is placed over the insulation and stopped from

compressing the insulation by the shoulder of the stud. The liner plate is installed with studs protruding through oversize washer and a nut welded to the stud. This construction permits the liner plate to expand with respect to the outer casing.

Duct Design

- All ducts are designed to withstand all loading from wind, seismic, thermal

insulation, lagging and the maximum positive and negative pressure to be expected under all operating.

- Design pressure : 600 mmH2O - Inlet/outlet duct consists of 6.0mm carbon steel outer casing, inside insulation,

and internal liner. - The duct is properly stiffened, reinforced and complete with necessary doors

and expansion joint.

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Thermal Insulation - The thermal insulation is applied to conserve energy, where accessible, and for

personal protection. - Ambient Temperature : 50.0 deg.C - Cold face Temperature : Below 60 deg.C - Wind velocity : 0.0 m/s - Heat Losses : < 230 w/m2 - The floors of modules and filler panels are provided with drains. - Duct and module is used insulation with CMS(Superwool) and Mineral wool. - All Drum, Header & Link is used insulation with mineral wool.

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3.2 Steam Drum for HP, IP and LP System The drums have factory installed steam separators of sufficient size and capacity to meet the HRSG steam purity guarantee requirement. The separators is baffle type with steam dryer. Two manways per drum (one each end) are provided. The manways are equipped with horizontally hinged door and manway cover. Drum volume is sufficient to accommodate drum level fluctuations during startup without “tripping” the boiler due to high or low water level condition. Steam drums are shipped with welded riser nozzle connections. Connections are all butt welds. The sufficient insulation thickness is provided to maintain the outside surface temperature below 60°C at an ambient temperature of 50°C in ambient air condition. Normal Water Level (NWL) shall be located at the drum centerline of the drum ID. All downcomers have vortex breakers.

HP Drum One(1) HP drum is installed per one(1) HRSG. The major specifications are as follows; - I.D : 1,830 mm. - Shell Length (welding to welding) : 11,700 mm. - Material (shell/heads) : SA299 Gr B - Head type : Hemi-sphere HP Drum Retention Time – A minimum of 3.0 minutes retention time is allowed. The definition of this 3.0 minute minimum HP Drum retention time allowance is the time during base load operation at maximum HP steam production from normal

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drum level to the low water level trip setting. This retention time provides a specific minimum time period to enable system reconfiguration prior to removal of the HRSG from service due to low drum volume.

IP Drum One(1) IP drum is installed per one(1) HRSG. The major specifications are as follows; - I.D : 1,524 mm. - Shell Length (welding to welding) : 7,000 mm. - Material (shell/heads) : SA516-70 - Head type : Elliptical Minimum retention time between normal water level and low water level trip is 8 minutes.

LP Drum One(1) LP drum is installed per one(1) HRSG. The major specifications are as follows; - I.D : 2,690 mm. - Shell Length (welding to welding) : 11,000 mm. - Material (shell/heads) : SA516-70 - Head type : Elliptical Minimum retention time between normal water level and low water level trip is 10 minutes.

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3.3 HP Superheaters Three(3) sections are installed for HP superheaters. The major specifications are as follows;

SH-HP3: - Tube O.D : 31.8 mm. - Finned Tube Length (gas path) : 21,650 mm. - Material (tube/fin) : A213-T91 / A240-TP409 - Finned tube Q’ty : 156 pcs/unit - Fin Q’ty : 250 fins/meter

SH-HP2: - Tube O.D : 31.8 mm. - Finned Tube Length (gas path) : 21,650 mm. - Material (tube/fin) : A213-T91 / A240-TP409 - Finned tube Q’ty : 234 pcs/unit - Fin Q’ty : 260 fins/meter

SH-HP1: - Tube O.D : 31.8 mm. - Finned Tube Length (gas path) : 21,650 mm. - Material (tube/fin) : A213-T11 / A240-TP409 - Finned tube Q’ty : 156 pcs/unit - Fin Q’ty : 260 fins/meter The high pressure superheaters are of finned tube design and arranged for efficient heat transfer. Steam side pressure drop is minimized, but be sufficient to achieve good steam flow distributions. The high pressure superheaters tube banks are interspersed in a series configuration as shown on the flow diagram so that all of the exhaust gas flows through the high pressure superheater.

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3.4 Reheaters

Two(2) sections are installed for RH system. The major specifications are as follows;

RH-IP2: - Tube O.D : 44.5 mm. - Finned Tube Length (gas path) : 21,650mm. - Material (tube/fin) : A213-T91 / A240-TP409 - Finned tube Q’ty : 234 pcs/unit - Fin Q’ty : 190 fins/meter

RH-IP1: - Tube O.D : 44.5 mm. - Finned Tube Length (gas path) : 21,650mm. - Material (tube/fin) : A213-T11 / A240-TP409 - Finned tube Q’ty : 234 pcs/unit - Fin Q’ty : 195 fins/meter

The reheater are of finned tube design and arranged for efficient heat transfer. Steam side pressure drop is minimized, but be sufficient to achieve good steam flow distribution. The reheater tube banks are interspersed in a series configuration as shown on the flow diagram so that all of the exhaust gas flows through the reheater.

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3.5 HP Evaporator

One(1) section is installed for HP evaporator system. The major specifications are as follows;

EV-HP (HAD10): - Tube O.D : 38.1 mm. - Finned Tube Length (gas path) : 21,650mm. - Material (tube/fin) : A210-C / A1008 - Finned tube Q’ty : 936 pcs/unit - Fin Q’ty : 260 fins/meter The high pressure evaporator is of finned tube design and arranged for efficient heat transfer. Steam side pressure drop is minimized, but be sufficient to achieve good steam flow distribution.

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3.6 HP Economizer

Two(2) sections are installed for HP economizer system. The major specifications are as follows;

EC-HP2 : - Tube O.D : 31.8 mm. - Finned Tube Length (gas path) : 21,650 mm. - Material (tube/fin) : A210-C / A1008 - Finned tube Q’ty : 936 pcs/unit - Fin Q’ty : 260 fins/meter

EC-HP1 : - Tube O.D : 31.8 mm. - Finned Tube Length (gas path) : 21,650 mm. - Material (tube/fin) : A210-C / A1008 - Finned tube Q’ty : 690 pcs/unit - Fin Q’ty : 260 fins/meter The high pressure economizers are of a finned tube design and arranged for efficient heat transfer. Steam side pressure drop is minimized, but be sufficient to achieve good steam flow distribution. The high pressure economizer is located parallel with intermediate pressure economizer (EC-IP) to maximize heat transfer.

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3.7 IP Superheater

One(1) section is installed for IP superheater. The major specifications are as follows;

SH-IP: - Tube O.D : 38.1 mm. - Finned Tube Length (gas path) : 21,650 mm. - Material (tube/fin) : A192 / A1008 - Finned tube Q’ty : 156 pcs/unit - Fin Q’ty : 250 fins/meter The intermediate pressure superheater is of finned tube design and configured for efficient heat transfer. Steam side pressure drop is minimized, but be sufficient to achieve good steam flow distribution. The intermediate pressure superheater is located in the gas path between the high pressure evaporator and the high pressure economizer.

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3.8 IP Evaporator

One(1) section is installed for IP evaporator system. The major specifications are as follows;

EV-IP: - Tube O.D : 38.1 mm. - Finned Tube Length (gas path) : 21,650 mm. - Material (tube/fin) : A192 / A1008 - Finned tube Q’ty : 468 pcs/unit - Fin Q’ty : 260 fins/meter The intermediate pressure evaporator is of finned tube design and configured for efficient heat transfer. Steam side pressure drop is minimized, but be sufficient to achieve good steam flow distribution.

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3.9 IP Economizer

One(1) section is installed for IP economizer system. The major specifications are as follows;

EC-IP: - Tube O.D : 31.8 mm. - Finned Tube Length (gas path) : 21,650 mm. - Material (tube/fin) : A192 / A1008 - Finned tube Q’ty : 90 pcs - Fin Q’ty : 260 fins/meter The intermediate pressure economizer is of finned tube design and configured for efficient heat transfer. Steam side pressure drop is minimized, but be sufficient to achieve good steam flow distribution. The intermediate pressure economizer is located parallel with high pressure economizer1 (EC-HP1) to maximize heat transfer. A water relief valve is provided at the inlet of the IP economizer.

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3.10 LP Superheater

One(1) section is installed for LP superheater system. The major specifications are as follows;

SH-LP: - Tube O.D : 38.1 mm. - Finned Tube Length (gas path) : 21,650 mm. - Material (tube/fin) : A192 / A1008 - Finned tube Q’ty : 156 pcs/unit - Fin Q’ty : 150 fins/meter The low pressure superheater is of finned tube design. Steam side pressure drop is minimized, but be sufficient to achieve good steam flow distribution. The low pressure superheater is located in the gas path between the intermediate pressure evaporator and the intermediate pressure economizer to get the LP-steam temperature specified.

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3.11 LP Evaporator

One(1) section is installed for LP evaporator system. The major specifications are as follows;

EV-LP: - Tube O.D : 38.1 mm. - Finned Tube Length (gas path) : 21,650 mm. - Material (tube/fin) : A192 / A1008 - Finned tube Q’ty : 780 pcs/unit - Fin Q’ty : 220 fins/meter The low pressure evaporator is of finned tube design. Steam side pressure drop is minimized, but be sufficient to achieve good steam flow distribution.

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3.12 Condensate Preheater

One(1) section is installed for Condensate Preheater system. The major specifications are as follows;

EC-PR: - Tube O.D : 31.8 mm. - Finned Tube Length (gas path) : 21,650 mm. - Material (tube/fin) : A192 / A1008 - Finned tube Q’ty : 1,092 pcs/unit - Fin Q’ty : 260 fins/meter The low pressure evaporator is of finned tube design. Steam side pressure drop is minimized, but be sufficient to achieve good steam flow distribution.

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3.13 Safety Valve

The purpose of the safety valves is to release the over pressure of the HRSG caused by blinking the steam turbine. - HP drum 1 : 153.0 barg (design pressure of HP drum) - HP drum 2 : 157.6 barg (not exceed design pressure x 1.03) - HPSH : 146.0 barg (HP drum design pressure - SH pressure drop -

margin) - HPSH ERV : 145.5 barg (HPSH set pressure -0.5 bar) - HPECO : 210.0 barg (design pressure of HPECO section) - IP drum 1 : 45.0 barg (design pressure of IP drum) - IP drum 2 : 46.4 barg (not exceed design pressure x 1.03) - IPSH : 43.0 barg (IP drum design pressure - SH pressure drop -

margin) - IPECO : 75 barg (design pressure of IPECON section) - LP drum 1 : 10.0 barg (design pressure of LP drum) - LP drum 2 : 10.3 barg (not exceed design pressure x 1.03) - LPSH : 9.0 barg (LP drum design pressure - SH pressure drop -

margin) - CPH : 40.0 barg (design pressure of CPH section) - CRH 1 : 43.4 barg (set pressure of IP superheater - pressure drop) - CRH 2 : 44.7 barg (not exceed set pressure x 1.03 ) - HOT RH : 40.5 barg (set pressure of cold rh1 - RH pressure drop -

margin)

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3.14 Vent Silencer

The purpose of the steam silencers is to release the noise of the safety valve caused by overpressure of each section. The common steam silencer is provided to the same steam or water conditions. Each of steam silencers has one(1) drain connection. The configurations are as follows and indicated on flow diagrams.

No Service Ope.

Pressure(bara)

Oper. Temp. (deg.C)

Design Flow (kg/s)

Allowance noise (SPL, dB(A))

Q'ty Per

HRSG(sets)

01 HP Drum #1 154.0 345 22.3 ≤ 110 1 02 HP Drum #2 158.6 347 22.3 ≤ 110 1

03 HP SH #1 147.0 567 14.9

≤ 110 1 HP Air Vent 147.0 567 3.0

04 HP SH #2 (ERV) 146.5 567 3.0 ≤ 110 1 05 IP Drum #1 46.0 259 3.7 ≤ 110 1 06 IP Drum #2 47.4 261 3.7 ≤ 110 1

07 IP SH 44.0 341 2.5

≤ 110 1 IP Air Vent 44.0 341 1.0

08 LP Drum #1 11.0 185 2.8 ≤ 110 1 09 LP Drum #2 11.3 186 2.8 ≤ 110 1 10 LP SH 10.0 259 1.9 ≤ 110 1 11 CRH #1 43.5 405 24.9 ≤ 110 1 12 CRH #2 44.8 405 24.9 ≤ 110 1 13 HRH 41.5 566 16.6 ≤ 110 1 14 Blowdown 1.1 103.0 6.0 ≤ 85 1 15 RH Startup Vent 41.5 566 25.9 ≤ 85 1 16 LP Startup Vent 10.0 259 3.8 ≤ 85 1

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3.15 Duct and Casing

Ducting is sufficiently rigid to avoid vibration and drumming when exposed to gas turbine exhaust flow over the complete flow range. Duct sections is suitably stiffened to minimize distortion and withstand seismic and wind loads. Duct plate is designed to limit the deflections to 1/100 of the span of plate between stiffeners, taking full advantage of multi-span continuity where appropriate, for normal operating conditions. Normal operating condition includes full dead load, pedestrian live load and maximum interior pressure loading.

Inlet Duct:

- Insulation type : Inside insulation - Insulation Thickness : 150 mm / 150 mm - Insulation material : CMS / Mineral - Density of insulation material : 128 kg/sq.m - Material for liner plant : SS409 x 2 mm

Casing Module

- Insulation type : Inside insulation - Insulation thickness : 300/250/150/50 mm - Insulation material : Sperwool / Mineral - Density of insulation material : 128 kg/sq.m - Material for liner plate : SS409 for High Temp - : C.S for Low Temp

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3.16 Expansion Joint

Expansion joints are provided where necessary such as guillotine damper outlet, HRSG inlet, HRSG outlet. These are flexible membrane type (fabric) and provided with internal plates to prevent eddies. . The expansion joint is designed to prevent flue gas leakage to the atmosphere and to absorb the all the movements of the exhaust ductwork system and interfacing equipment such as axial compression, axial extension and lateral displacements.

< Non-Metallic Expansion Joint >

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3.17 Insulation and Lagging System (For Duct & Casing)

The thermal insulation are provided so that the surface temperature of all exposed portions of the HRSG casing/duct shall not exceed 60 oC at the design maximum ambient condition. The insulation is installed in a new and clean condition and is free of voids. Insulation seams is overlapped. Internal lagging is applied over the insulation in adequate spaces to allow movement relative to attachment studs and eliminate stressing and buckling. Liner sections are overlap in the direction of gas flow. The liner and attachment studs are designed to ensure that the insulation will not be exposed to the hot gas flow for any thermal movement. The lagging is 2.0mm minimum thickness of stainless steel (for high temperature zone) or carbon steel (for low temperature zone). Item Unit Inlet

DuctModule

#1Module

#2Module

#3Module

#4Module

#5Module

#6OutletDuct

HPSH3IPRH2

HPSH2IPRH1

HPSH1HPEVA

IPSHHPECO2IPEVALPSH

HPECO1IPECOLPEVA

CPH *1)

Operation Max. Operation Temp. oC 649 649 582 520 347 261 175 160

Casing Surface Temp. oC < 60 < 60 < 60 < 60 < 60 < 60 < 60 < 60

Design Pressure (+) mmH2O 600 600 600 600 600 600 600 600

Material - C.S C.S C.S C.S C.S C.S C.S C.S

Thickness mm 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0

Insulation Design Gas Temp. oC 659 659 592 530 357 271 185 170

(Liner Side) Material - CMS Wool CMS Wool CMS Wool CMS Wool

Thickness mm 150 150 100 100

Insulation Surface Insu. Temp. oC 431 431 429 450 357 271 185 170

(Casing Side) Material - Mineral Mineral Mineral Mineral Mineral Mineral Mineral Mineral

Thickness mm 150 150 150 150 150 150 50 50

Liner Design Gas Temp. 659 659 592 530 357 271 185 170

Material - 409SS 409SS 409SS 409SS C.S C.S C.S C.S

Thickness (Others) mm 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0

< Specification for Insulation and Lagging system (Casing/Duct) >

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3.18 Access Door

Sufficient access doors, 460mm x 610mm minimum opening, is provided in each cavity on one side of the HRSG to allow easy for inspection and maintenance of all heat transfer surfaces. Access doors are quick opening and vertically hinged so those doors swing open horizontally. Grab bars are provided to aid personnel in gaining access to the HRSG. The doors are internally insulated and designed to operate at the same temperature as the surrounding ductwork.

< Access Doors - Typical >

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3.19 Gas Bypass Baffle System

A gas bypass baffle system is provided to restrict bypassing of exhaust gas around the heat transfer-sections. The following sectional baffles are installed at various section of exhaust gas passage of HRSG;

Header Box Baffles

The each headers are located at front/rear header box area. Since hot gas passes through around finned tube bundles, all headers is separated with main stream of hot gas passage by inside baffle system. Between outer casing and front/rear inside baffle, there is dead flow zone which mainly for inlet/out headers of finned tube bundles. Since there is no heat transfer section, no hot gas shall be introduced into header box area. For this purpose, front/read header box entrance are sealed with header box baffles respectively.

< Front Header Box Baffle >

Rear header box baffle is installed as vertical direction to minimize gas bypass and to assure uniform hot gas distribution around first heating surface bundles.

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< Rear Header Box Baffle >

Division Baffles

Front/rear header boxes are divided further by division baffles. Division baffle prevent the hot gas bypass around headers, if any. So, it is important to check condition of division baffle by visual inspection according to scheduled maintenance program.

< Division Baffle >

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Partition Baffles Partition baffle is one of most important baffle system in HRSG since it provides main blockage against high speed of hot gas from combustion turbine. Partition baffle also provides several access doors between finned tube bundles and header boxes for easy inspection and maintenance activity. During the inspection, the condition of partition baffles shall be checked carefully to prevent any hot gas bypass, if have.

< Partition Baffle >

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3.20 Stack

The HRSG main exhaust stack is designed and fabricated in accordance with ASME STS-1. The design of the stack is considered the effects of nearby structures as specified in ASME STS-1. Stack height for the HRSG Exhaust Stack is 80 m from the support elevation to the top of the stack. Stack internal diameter is 5.2 m. The effluent matters such as Sox, NOx, particles from combustion turbine are emitted through the stack at sufficient high elevation and disperse into atmosphere. Eventually the contents of emission is diluted on ground within acceptable ranges. Stack is insulated with 50 mm mineral wool externally to prevent condensing of water in exhaust gas and personnel protection purpose from hot surfaces of stack shell.

< HSRG Main Exhaust Stack >

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3.21 Stack Silencer

The purpose of the stack silencer is to reduce the noise emission from HRSG exhaust gas caused by GT sources. The stack silencer is installed inside of main stack. The silencer is composed of gas baffles, which is lagged by perforated plates to reduce the sound power level. These baffles are supported by brackets and supporting pipe attached on stack inside.

< Stack Silencer >

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3.22 Support Structure

All main frame supports and field connections is structural steel beams, channels or angles designed for, and employing, high strength bolts per AISC Standards. All base plates for supporting of structure and components is provided. The Supplier is weld base plates to the HRSG columns at the factory. All other required installation hardware, i.e., anti-friction plates, shims, is provided unless otherwise specified. This HRSG structure is also be used to support stairs, platforms, ladders and piping. The steel structure is designed for the specified environmental and seismic conditions. Wind loads, snow loads and earthquake forces will be taken as the basis for calculations for the steel structure of the HRSG, and main stacks.

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3.23 Stair, Platforms and Ladders

The HRSG and its accessory equipment are fitted with adequate platforms, galleries, stairways and ladders to allow safe evacuation. And also Stairs, platforms and ladders allow easy and safe access into all work areas of the HRSG. The design of the stairs, platforms and ladders meet the relevant international code and standards. Platform elevations will be such that any valve or station instrument is easily accessible and can be operated from the platform without the use of ladders or special operating devices. The minimum platform width is 1.0 meter of unobstructed clear passage. Walk-overs are provided over any obstacle (piping, valve, etc.) which prohibits safe and easy passage on any platform. This can be deviated depends on the site condition. Safety cages are provided on ladders in compliance with the national & local requirements. All HRSG platforms within one block are interconnected at two levels, one of which are at the drum level.

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3.24 Instrumentation and Controls

Instruments and instrumentation systems used for measurement and control is identified in P&Ids. A representative steam/water sampling ports are provided for main steam of downstream of superheater, saturated steam piping of downstream of drums, downcomer piping. Gauge glass assemblies are provided in accordance with the requirements of ASME Boiler & Pressure Vessel Code, Section I and the HRSG flow diagram and additionally remote level indicators per each drum are provided. The HP, IP and LP drum gage glasses have adequate view port length to cover the entire drum level operating range between high and low trip points. The temperature is normally measured by temperature elements such as thermocoules and assembly is designed to fit properly in the thermowell. For local indicator in the field, filled system and bi-metallic type dial thermometers are used. For pressure measuring, measuring tapping points are provided with an isolating valve and an additional block valve and vent valve are supplied adjacent to the transducer. For flow measuring, nozzle or orifice meters are used which is constructed, arranged and instrumented in accordance with relevant ISO standards. The HRSG designed for electric utility service, which includes continuous at base load and for prolonged periods, daily startup and shutdown, load following with loads varying as specified.

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3.25 Piping

The HRSG piping system is designed to withstand the design pressures and temperatures for the design lifetime of the plant. The steam lines incorporates sufficient thermocouples for monitoring purpose.

Applicable Code: ASME Section I (HRSG Proper) and ASME B31.1 (Boiler External Proper) Feedwater piping is to be supplied from the boiler feed pump discharge to the economizer inlet connection, including an automatic feed control valve of approved design with inlet and outlet isolating valves and a bypass valve, and a stop and check valve at the economizer inlet HP/IP steam piping is to be supplied from the boiler outlet manifold to HRSG OEM’ scope of supply (steam stop valve) including a stop valve with a small by-pass valve and sepate check valve at the superheater outlet. A warming drain valve and piping is provided at each superheater outlet to enable a flow of steam through the superheater during pressure raising of the HRSG All steam pipework are carefully designed to ensure that it is fully drainable to an atmospheric drains vessel. Drain and vent valves are supplied for start-up and shutdown purpose. All dosing pipe-work are in stainless steel.

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3.26 Attemperator

To control the main steam and hot reheat temperature especially during high ambient condition, the attemperator is installed in HRSG proper piping between heat transfer sections of the HP superheater and the reheater. A thermal liner is included to prevent spray water impingement on the main steam piping. A straight run of pipe is provided both on the upstream and downstream side of the spray nozzle to assure good atomization. Steam from the superheater/reheater is conditioned to meet the steam turbine manufacturers requirements at all times. The attemperator and associated spray water control valves are sized for the full continuous operating range and 100 percent of the maximum steam mass flow rate over all continuous operating pressures of the HRSG. Attemperators are fitted with spray water stop valve to avoid reduction in final steam temperature due to the leakage through the control valves.

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< Attemperator – Nozzle Parts >

< Attemperator – Control Actuator Parts >

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3.27 Blowdown Tank

The flash tank is installed as a vertically arranged, free standing cylindrical pressure vessel with dished ends, equipped with support feet and vent pipe with silencer. All necessary nozzles are provided including a manhole. The major specifications are as follows;

Blowdown tank: - O.D : 2,076 mm

- Shell Length (T.L to T.L ) : 3,200 mm. - Material (shell/head) : SA516-70 - Head type : Elliptical - Vent pipe size : 20” - Installed elevation : EL 4,500 mm (Ground Level)

< Blowdown Tank >

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4.0 Inspection and Maintenance Procedure Doc.No :xxxxx Rev. -

4.0 INSPECTION AND MAINTENANCE PROCEDURE

4.1 Notice

4.2 General

4.3 HRSG External Inspection

4.4 HRSG Internal Inspection

4.5 Table of Maintenance Inspection

Attachment 1 Accessibility of HRSG Header Zone

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4.0 Inspection and Maintenance Procedure Doc.No :xxxxx Page 1 of 12 Rev. -

4.0 INSPECTION AND MAINTENANCE PROCEDURE

4.1 Notice

The inspections for the HRSG are to be performed on a time schedule compatible and concurrent with the gas turbine Planned Maintenance requirements. In addition, the downtime hours for Unplanned Maintenance Outages (not planned well in advance) for the HRSG should be performed on an opportunistic basis, concurrent with outages on other plant equipment.

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4.2 General

The HRSG operator must have full knowledge of the characteristics and correct operating procedures of the HRSG and associated equipment before placing the unit in service. It is important, as soon as possible after the start of the HRSG operation, to inspect the HRSG exterior and interior to confirm whether there is any abnormal condition: - Excessive thermal expansion, - Excessive pipe vibration, - Drums high temperature and pressure gradients. This detailed inspection shall be performed on each component.

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4.3 HRSG External Inspection

After the HRSG has been shut down and sufficiently cooled, the HRSG external components must be inspected. The tubes shall be cleaned carefully and checked for corrosion, deformation, bulging, burning and cracking. The HRSG proper walls, especially the casing, doors and expansion bellows and joints, must be inspected for potential leak of flue gas.

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4.4 HRSG Internal Inspection

HRSG interior shall be examined during every periodical inspection. The following items represent a specific check list:

Drum Inspection 1) Take off the manhole cover and check whether steam drum internals are

securely fixed. Also verify possible contamination.

2) Confirm that the steam stop, feed water, blow down and chemical injection valves are completely and firmly closed and locked in "Closed" position.

3) Provide all the isolation valves with appropriate holding tags, so that other persons will not inadvertently open them.

4) Seals around manway doors

5) Inside around manway doors

6) Upon entering into the HRSG drum, check for corrosion and pitting, if the HRSG water properties during the HRSG wet lay-up are appropriate, pitting will rarely occur inside the steam drum.

7) The main cause is the presence of dissolved oxygen in feed water, so Pitting can be completely prevented if the feed water and HRSG water control is performed correctly.

8) When mounting the internals, pay attention to the following :

- Fully understand beforehand the assembling procedure and the internals configuration.

- Because the internals are composed of a large number of parts, it is recommended to sort them into two separate groups :

- Those to be mounted above water level and those to be mounted below water level.

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This recommendation will help avoiding re-installation mistakes. - During the time of re-assembly, fully inspect all parts to check whether

there is any future possibility of steam water mixture, dry steam and feed water, etc., leaking from joints and being mixed with each other.

- In particular, the portion near the dry steam outlet should be completely tight.

- When new packing have been inserted in bolted joints, the bolts should be finally re-tightened after a preliminary tightening.

- The joints that do not use any packing should be well fitted prior to the bolts tightening.

9) The internals must be fully inspected also during their re-assembly.

10) After re-assembly completion, it is impossible to check the correct re-

assembly of all components.

11) An incomplete tightness of the internals will cause damage to the superheater tubes, due to carry-over. Even only one missing bolt or incomplete or damaged packing can allow above carry-over to occur. Therefore, careful attention shall be provided when reassembling the drum internals.

Superheater Inspection

The inspection and maintenance of the superheater shall comply with the following requirements: 1) When inspecting the drum, be sure to inspect the superheater also. 2) Check the superheater for alignment, deformation and bulging. 3) Inspect the condition of superheater supports and repair the defective parts,

if any, immediately. 4) Check the superheater, header and steam drum interior for carried over

solids and, if present, clean them immediately. Also, determine and eliminate the source.

The superheater must be correctly operated, inspected and subjected to proper

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maintenance.

Superheater Cleaning 1) External cleaning

When operated for a long period of time, keep the exterior of the superheater as clean as possible. If the superheater is contaminated, the flue gas will not have an uniform flow. Therefore, the heat transfer drops causing local overheating against which precautions should be taken.

2) Internal cleaning To keep the interior of the superheater clean, the feed water and the related water treatment must be performed correctly. Also, the steam humidity and the solid content of the steam entering the superheater shall be kept within the specified limits. The following are causes of adhesion of scales to the superheater inside wall: a) Operation in over load conditions/parameters or sudden load fluctuation,

high water level, priming or increase of HRSG water concentration values, etc.

b) Adhesion of scale generates a reduction of superheater heat rate and a steam pressure drop. Therefore, the superheater could be damaged, unless the scales are removed.

c) The HRSG manufacturer shall be consulted prior the scale removal. When the superheater steam pressure drop is measured periodically, the adhesion of scales can be judged. However, the pressure measurements have to be made under the same load.

Notes: 1. A periodic measurement of superheater steam pressure drop will allow a

scales deposit evaluation 2. The pressure measurements shall be performed under the same HRSG load

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conditions, for evaluation consistency.

Evaporator and Economizer Inspection The evaporator and economizer are most import section for steam generation. Before the HRSG startup, the evaporator and economizer must be externally inspected and cleaned, as required.

Miscellaneous Inspection 1) Inspect and clean the flue gas side of HRSG heating surfaces. 2) The following inspections, but not limited to, must be performed annually :

a) Complete inspection of HRSG interior b) Remove(eliminate) the scale deposits, if required c) Verify the superheater and economizer performances d) Tubes detailed inspection, especially after tube failures and/or expected

tube failures. e) Metallurgical examination and analysis of tube sections. (see Note 1) f) Tube sections chemical analysis of deposits. (see Note 1)

Notes : 1. Inspection items must be performed when tube failures have occurred, or

are expected to occur, and no reasons have been clearly identified. 2. Scale inspection shall be performed by qualified persons for this area of

expertise. 3. Separate records shall be kept for each inspection in accordance with Owner

approved procedure. 4. The records shall be kept and compared with the actual conditions, at

different operation intervals.

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4.5 Table of Maintenance Inspection

(Periodic Maintenance Inspection)

Interval/ Frequency

Item Standard inspection

items Standard measures

Daily

Boiler feed water chemistry

Perform feed water chemistry analysis once every 24 hour operation

Sampling to be performed from boiler feed water pumps discharge

HRSG water Chemistry

Perform HRSG water inspection analysis once every 24 hour operation.

Blowing is necessary to adjust boiler drum water

Piping system Check for corrosion and leakage

Repair leaking part.

Operation recording

Complete all required data in the Operation. Maintenance Log (Record Book) every hour, during HRSG operation / maintenance

1 Pressure Drum, Main steam, Feed water, Low pressure steam

2 Temperature SH outlet steam, G/T exhaust gas, Feed water, and Flue gas, etc.

3 Level Steam drums 4 Draft Losses G/T exhaust gas and flue

gas 5 Flow rate

Feed water, Main steam and Low pressure

6 Others Conductivity and/or pH of feed water and HRSG water

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Interval/ Frequency



Weekly

Main stop valves, safety relief valves.

Check the valves. 1 Check operation and leakage of valves.

2 Check whether the safety relief valves work before their connection to related steam headers.

Drum, casing, manholes, etc.

Check whether the nuts are tightened.

1 Tighten the nuts, if loose. 2 Change packing in case of

leakage(pay attention to the lid and the contact with seat).

Before each

startup

Boiler inside Check whether tools and rags are left inside.

1 Clean 2 Ensure that no foreign

object is left inside HRSG Boiler tubes Superheater tubes

Check for bulging, blow, soil

1 Repair or replace, as necessary.

2 Investigate the cause of bulging

3 Perform pressure hydro-test after replacing tube(s).

Casing (Bellows, Expansion joints)

Check flue gas leakage during pressure rise.

Repair the component leakage during shutdown period.

Water level gauge

Check whether the water level gauge operates properly.

Check the measurements.

Safety valve Inspect valve for leakage, etc.

Eliminate leakage if any.

Riser tubes Drums

Check corrosion conditions.

Check drum components, as applicable.

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Interval/ Frequency



Components cleaning

HRSG casing Check for corrosion and leakage.

1 Treat corroded part and paint.

2 Perform casing leakage test and repair leaking part.

Interior cleaning

Water level gauge

Check the conditions of water level gauge

1 Repair, if any deposits or leak are found.

2 Check the standard reading.

HRSG accessories

Check for any abnormality. Make sure that they do not leak and that they operate smoothly

1 Replace defective accessories

2 Tighten bolts, etc., if loose.

Monthly Pressure gauges, thermometers, flow-meters.

Check whether the measurements are accurate.

Compare with a standard instrument, as required by the national regulation.

Every three

months

Casing Check the condition, for corrosion and leakage.

1 Treat corroded part and paint.

2 Repair leaking part.

Every six months

Safety relief valves(SRV)

Check the conditions of valves, seats, springs, etc. After revision and repair, if required, assemble and test SRVs and adjust them.

1 Lapping of valves. 2 Maintain the working parts

(surfaces)

Valves & Cocks Packing

Check leaking part (packing). Check whether switching parts work properly. Examine leaking parts.

1 Lapping of valves. 2 Lubricate switching

devices. 3 Replace packing of leaking

parts. 4 Replace with new packing.

Annually Pressure components

Check the external and internal surfaces.

In case of corrosion or pitting etc., investigate causes and replace with new one, if necessary.

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Interval/ Frequency



Instruments Check pressure gauges, thermometers, flowmeters,O2 meter and all other instruments.

1. Compare them with standard instruments.

2. Repair if reading errors are not acceptable.

3. Clean and lubricate lapping parts, if necessary.

4. Comply with national regulation.

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Attachment 1 Accessibility of HRSG Header Zone for Qurayyah Project (Accessibility Study Report, Dated on 2010.03.24)

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Accessibility of HRSG Header Zonefor Qurayyah Project

Department : HRSG Design Team-1Date : 2010. 03. 24

1 Pages30621127-000-3DT-00019-000 of 248

2

Contents

1. Introduction

2. Related HRSG’s Drawings

3. Recommend Access Sequences to HRSG Header Zones

4. Conclusion

5. Overall access way toward the HRSG header zones

6. Access Process of Each Header Zones

7. HRSG Inside Structures of Non-Pressure Part

8. HRSG Inside Structures of Pressure Part

9. Man Hole Location of HRSG Casing

3

2 Pages

3

4

4

5

7

15

18

21

Pages

10. Photos of Previous Project 23

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3

The accessibilities into the HRSG inside and the header zones are specified on the following based on the current design status.

2. Related HRSG’s Drawings2-1. Completed Drawings at the last DRM in Chicago - HRSG General Arrangement Drawings- HRSG Pressure Part Drawings.

2-2. Open Drawings at the last DRM in Chicago - HRSG Platform Arrangement Drawings,- HRSG Casing Arrangement Drawings,- HRSG Baffle Arrangement Drawings,

* NotesThe inside structure consists of the gas guide baffle plates, the tube sheet plates, and so on. The

inside structure is not specified fully on the HRSG GA and PPA drawings, but on the HRSG Platform/Casing/Baffle Arrangement Drawings which are not completed yet. Those drawings plan to be completed by the end of March.

3 Pages

1. Introduction

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4

3. Recommend Access Sequences to HRSG Header ZonesAccess into the HRSG via the man hole on the casing

Access into the header zone via the doors of the tube sheet, the gas baffle plate, or the gas guide baffle plate. (Alternative)

Approach the header zones by stepping on the foothold attached on the liner plate of the casing inside.

4. Accessibility Check Sheet

CONCLUSION

1. There is no trouble to access all header zones.

2. All attachment components (M/H, Door, and others) are provided to make the access into the header zones easy.

OKTop side of Headers on HRSG Rear08

OKUpper side of Headers on HRSG Rear07

OKMiddle side of Headers on HRSG Rear06

OKLower side of Headers on HRSG Rear05

OKBottom side of Headers on HRSG Rear04

OKUpper side of Headers on HRSG Front03

OKMiddle side of Headers on HRSG Front02

OKLower side of Headers on HRSG Front01

RemarkAccessibilityLocationZoneNo.

4 Pages30621127-000-3DT-00019-000 of 248

5

Zone 01

5 Pages


Zone 02

Zone 03

Zone 04

Zone 05

Zone 06

Zone 07

Zone 08

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6

Zone 01

Zone 02

Zone 03

Zone 04

Zone 05

Zone 06

Zone 07

Zone 08

6 Pages


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7

Open the man hole on the casing and go into the HRSG inside

Open the door on the gas guide baffle plate and approach the upper side of the header zone

Open the door on the floor baffle plate and approach the lower side of the header zone

Opposed side M/H

Opposed side M/H

Open the man hole on the oppose side of the casing and go into the HRSG inside

Open the door on the tube sheet plate and approach the header zone

7 Pages

6. Access process of HRSG Header Zone 01 (Lower side of Header on HRSG Front)

- Recommend access sequences toward zone 01

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8

6. Access process of HRSG Header Zone 02 (Middle side of Header on HRSG Front)

Opposed side M/H


Open the door on the gas guide baffle plate and on the floor baffle plate in turn, and approach the upper side of the header zone

Open the door on the floor baffle plate from the zone 01 and approach the bottom side of the header zone

Open the man hole on the oppose side of the casing and go into the HRSG inside

Open the door on the tube sheet plate and approach the upper side of the header zone

8 Pages


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9

Opposed side M/H


Open the door on the gas guide baffle plate and approach each header zone

Open the man hole on the oppose side casing and go into the HRSG inside

Open the door on the tube sheet plate and approach the lower header

9 Pages

6. Access process of HRSG Header Zone 03 (Upper side of Header on HRSG Front)


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10

6. Access process of HRSG Header Zone 04 (Bottom side of Header on HRSG Rear)

Opposed side M/H


Open the door on the gas guide baffle plate and approach the bottom side of the header zone

Open the door on the tube sheet plate and approach the bottom side of the header zone


Open the door on the gas guide baffle plate and approach the upper side of the header

10 Pages


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11

6. Access process of HRSG Header Zone 05 (Lower side of Header on HRSG Rear)

Opposed side M/H


Open the door on the tube sheet plate and approach the header zone


Open the door on the gas guide baffle plate and approach the upper side of the header

11 Pages


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12

6. Access process of HRSG Header Zone 06 (Middle side of Header on HRSG Rear)


Open the door on the tube sheet plate and approach the upper side of the header zone

Open the door on the local floor baffle plate and approach the middle side of the header zone


Open the door on the gas guide baffle plate and approach the middle side of the header

Open the door on the floor baffle plate and approach the bottom side of the header zone

Opposed side M/H

12 Pages


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13

Opposed side M/H

Open the manhole on the casing and go into the HRSG inside

Open the door on the tube sheet plate from zone 06 and go into the bottom side of the header zone on the local floor baffle

Open the door on the floor baffle plate and go into the upper side of the header zone


Open the doors in turn on the gas guide baffle plate and on the floor baffle plate, and approach the upper side of the header zone

Open the door on tube sheet plate and approach the upper side of the header

13 Pages

6. Access process of HRSG Header Zone 07 (Upper side of Header on HRSG Rear)


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14


Open the doors in turn on the gas guide baffle plate and on the floor baffle plate, and approach the header zone

14 Pages

6. Access process of HRSG Header Zone 08 (Top side of Header on HRSG Rear)

Opposed side M/H


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15

1

3

2

5

3

6

15 Pages

- Main Components1. Gas guide baffle Plate2. Floor baffle plate3. Door on gas guide baffle plate or Door on floor baffle plate4. Foothold on casing inside liner plate5. Local floor baffle plate with door6. Header support

7. HRSG Inside Structures of Non-Pressure Part

4

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16

1. Gas guide baffle Plate

3. Door on gas guide baffle plate

2. Floor baffle plate

4. Foothold

5. Local floor baffle plate with door

6. Header support

3. Door on floor baffle plate


16 Pages

7. HRSG Inside Structures of Non-Pressure Part7-1. 3D Image

4. Foothold

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17

1. Gas guide baffle Plate

2. Floor baffle plate

6. Header support


- The main function of the gas baffle plate is to prevent the inflow gas to the header zone, and to guide the gas flow.- The gas baffle plate provides the doors as well on the vertical side or the floor side to help the inside access.

17 Pages

7. HRSG Inside Structures of Non-Pressure Part7-2. Large-scale image of 3D Modeling

Gas guide baffle between hanger bar

Door on Gas guide baffle

3. Door on floor baffle plate

4. Foothold

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18

8. HRSG Inside Structures of Pressure Part

1

4

2

3

18 Pages

- Main components1. Tube Module with Header pipe2. Tube sheet plate3. Hanger bar4. Doors on both end of tube sheet.

4

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191.Tube Module with Header Pipe

2. Tube sheet plate

4. Door on tube sheet

19 Pages

8. HRSG Inside Structures of Pressure Part8-1. 3D Image

3. hanger bar

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20

- The tube sheet plate have access door holes and divide two(2) separated plate depended on two (2) tube module rows.

2. Tube sheet plate

4. Door on tube sheet

3. hanger bar

20 Pages

8. HRSG Inside Structures of Pressure Part8-2. Large-scale Image of 3D Modeling Door on Tube Sheet Plate

Tube Sheet Plates

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21

21 Pages

9. Man Hole Location of HRSG Casing-The man-holes are provided on the outside of the HRSG casing to make the access

on the platforms easy. (Refer to the 3D image on the next page)

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22

22 Pages

9. Man Hole Location of HRSG Casing9-1. 3D Image-The drawings of the casing designed with the man-holes will be completed and released aroundthe end of March.

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23

10. Photos of Previous ProjectDoors on tube sheetDoors on gas baffle plate

Header Zone

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24

E.O.D

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Qurayyah CCPP HRSG

5.0 HRSG Malfunction and Remedies Doc.No :xxxxx Rev. -

5.0 HRSG MALFUNCTION AND REMEDIES

5.1 Low Water Level

5.2 Tube Failure

5.3 Table of Malfunctions and Remedies

Appendix 1 Rectification Method of the Defected Finned Tubes placed in Middle of Module for Vertical Type HRSG (Specification No. DS-2810-HME001)

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5.0 HRSG Malfunction and Remedies Doc.No :xxxxx Page 1 of 7 Rev. -

5.0 HRSG MALFUNCTION AND REMEDIES

5.1 Low Water Level

For a satisfactory operation of the HRSG, the water in all drums should be maintained at the normal water level. The operator responsible for maintaining the drum water level within specified limits, should always watch and control the water level, in conjunction with all related instrumentation and controls, including the automatic level controls. When there is no reliable method to immediately recover and stabilize the water level, the operator is required to: 1) Follow the combined cycle (CC) plant operating procedures, the Combined

Cycle Plant will be transfer to shutdown mode.

2) Ensure that the GT connected to the HRSG with Low Water level problem is shutdown.

3) Stop the supply of feed water.

If the feed water is still being supplied, switch over the automatic feed water controller to "Manual", to gradually decrease the feed water flow (never increase the feed water supply). The purpose for gradual reduction of feed water flow by "Manual", as mentioned above, is to prevent a rapid cooling of the HRSG pressure parts. The main steam stop valve shall be closed when almost no more steam generation can be monitored.

4) Reduce the steam pressure Gradually reduce steam pressure by opening the start-up blow valve or vent valve.

5) HRSG Inspection The following inspections/verifications must be performed: - Determine the cause of low water level - Inspect the HRSG pressure parts in order to determine whether they are

overheated - Whether there are leakage and/or deformation, etc.

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Note) 1 Following the confirmation of HRSG normal condition, the operator must

proceed with the startup, as required, in accordance with the approved procedures.

2 Above paragraph was written assuming the low water level is due to a leak. In case of low water level by pump failure or valve failure, the operator is required to action same as above step 4 and 5.

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5.2 Tube Failure

When leakage is suspected, several steps should be taken by the operator. These are recommendations only, and are not intended to replace the judgement of the operators, responsible for the equipment’s operation. Operation with leaking tubes may damage other tubes and, therefore, a major repair activity may be required instead of a single short one. Refer to Appendix 1, Repair Procedure of Harp Assembly Tube Leakage. The decision to shutdown the HRSG must be made in accordance with plant operation procedures, taking also in consideration all circumstances, including the advantages and disadvantages of keeping the unit in operation. - In the situation of a major water leakage, in conjunction with the impossibility to

maintain the water level in the steam drum by the feed water flow control, the HRSG shall be shut-down.

- Also, in the abnormal situation when it is impossible to control the drum water level at a normal level by the feed water flow control, the following actions must be taken :

1) Follow the plant procedures to shutdown the GT. 2) Stop the feed water supply to the HRSG. 3) HRSG Inspection

When the HRSG is cold enough to permit access, inspect in detail the degree of damage to the boiler pressure parts. After making the necessary repairs on the damaged parts, a hydraulic test shall be performed to examine all pressure parts. The restart of the HRSG shall be performed in accordance with the approved procedures.

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5.3 Table of Malfunction and Remedies

Trouble or abnormality Causes Action

High water level (within the visual range on the water gauge)

a) Insufficient operation of feed water control

1. Change over to manual operationAnd drop the water level.

2. Readjustment of control valve

b) Sudden increase of load 1. Reduce the water level before the load is increased. 2. Reduce the quantity of feed water.

Drop of water level (outside the range of visibility on water level gauge)

a) Insufficient operation of feed water control valves. b) Trouble with feed water pump c) Insufficient quantity of feed water

1. Initiate the HRSG isolation. 2. Admit feed water flow after the HRSG is cooled. 3. In case of tube leak refer to “Tube Failure” section.

Low water level (within the range of visibility on water level gauge)

a) Insufficient operation of feed water control valves. b) Sudden decrease of the load

In abnormal situations, if necessary ; 1. Change over to manual operation and admit feed water flow. 2. Readjustment of the control valves. 3. Raise the water level. 4. Never increase rapidly the quantity of feed water.

Sudden decrease of water level (water level going rapidly down)

a) Insufficient operation of feed water control valve b) Feed water pump trouble c) Piping system leakage

1. HRSG shutdown and isolation 2. Change over from DCS operation to manual operation(in abnormal situations) 3. Shut off the main steam isolation valve. 4. In case of high-high or low-low water levels not clear on the water gauge, shutdown the HRSG and operate the blowdown (use drain valve on water level gauge.)

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Sudden increase of water level (above the visual range of water level gauge)

a) Incorrect operation of feed water control valve b) Sudden increase of load. (decrease of drum pressure because of sudden increase of drum level). NOTE : Item b) does not occur during normal HRSG operation.

1. After the boiler is shutdown and isolated, blow the water thru the blowdown valves till it reaches the normal water level. 2. Decrease Combustion Turbine exhaust gas flow and pressure.

Boiler water Alkalinity (pH) too high

a) Insufficient quantity of HRSG blow down b) Inadequate operation of

the chemical injection

1. Adequate control of HRSG blowdown. 2. Adjust chemical injection.

Boiler water Alkalinity (pH) too low

a) Too much HRSG blowdown b) Inadequate operation of the chemical injection

1. Adequate control of HRSG blowdown.

2. Adjust chemical injection.

Salt content of feed water and HRSG water too high

a) Insufficient quantity of blow down b) Problems with the cycle make up water

1. Adequate regulation of blowdown.2. Check makes up water quality.

Priming or carry-over (SiO2 and TDS content in the HRSG)

a) High concentration in drum water b) Water level too high c) Sudden change of the load d) Pressure drop e) Overload f) Malfunction of drum internals

1. Increase the blowdown 2. Investigation of feed water control valves 3. Water treating chemical

operation investigation 4. Pay attention to the load 5. Check the physical condition of system dryers

Scale and sludge

a) Hardness contents in feed water too high b) Oil and grease are mixed in feed water c) Inadequate operation of

the feed water chemical treatment, in the drum d) Inadequate number of

blowdow operations

1. Investigation of hardness in feed water 2. Adequate operation of the feed water chemical treatment, in the drum 3. Improve the make-up water and chemical injection systems operation. 4. Investigation of PO4 & pH

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Tube leak a) Defective material b) Blockage of the feed water circulation. c) Scale deposits on the interior surface of the tubes.

1. When tube leaks occur, the actions indicated in “Tube Failure” section shall be taken.

2. Inspection after HRSG shutdown.

Flue gas temperature too high at HRSG duct inlet

a) Turbine exhaust gas flow temperature high b) Fouling of heating surface c) After burning

1. Investigate the gas turbine. 2.Adequate regulation of gas

pressure and gas temperature per Heat Balance Cases.

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Appendix 1

Rectification Method of the Defected Finned Tubes placed in Middle of Module for Vertical Type HRSG (Specification No. DS-2810-HME001)

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Specification No. : DS-2810-HME001

Rectification Method of the Defected Finned Tubes Placed in Middle of Module

for Vertical Type HRSG (Qurayyah Add-on CCPP Project)

HRSG Manufacturing Engineering Team DOOSAN Heavy Industries

& Construction Co., Ltd.

2

1 W. H Jin. Mar 24 2010 S. H Ryu. Mar 24 2010

0 W. H Jin. Feb 25 2010 S. H Ryu. Feb 25 2010

Rev. Prepared Reviewed & Approved Remarks

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Page : 2 OF 21

1.0 Introduction.

This specification defines rectification method of the defected finned tubes as like water or steam leakages during hydro static test, commissioning or commercial operation of plant which are positioned in middle of module for Qurayyah add-on CCPP HRSG.

2.0 Reference Code

ASME Section I : Power Boiler ASME Section II : Materials ASME Section V : Non-destructive Examination ASME Section Ⅸ : Welding and Brazing Qualification. NBIC

3.0 Preparation

For the rectification of the defected finned tubes, following facilities and tools must be prepared before commence to works.

TIG Welding Machine including electrode Gas Flame Torch and Relevant Facilities as like Oxygen Gas and horse Grinders (4”, 8” and Chalk Grinder) Driver for removal of finned tubes Steel wire or rope Lightening Facilities Scaffolding if necessary Portable electric cutter (Saw) Argon gas and distributer Others

4.0 Rectification Methods 4.1 Type-A

: By making an access space adjacent to the defected Zone

To make an access space adjacent to defected zone, several finned tubes should be cut according to below conception and dimension. The cutting length and quantity shall be decided based on location of the defected finned tube considering workability. Basically, welder should access freely without any other obstruction to weld the defected area. Advantages for this method

- The reduction of heat transfer space can be minimized

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Disadvantages for this method

- Rectification time will be taken longer than plugging method - Radiographic examination is required for butt weld - The sound finned tubes should be cut for making an access space

- Skilled welder is necessary Detail Rectification Sequence

1) Verify the defected finned tube exactly

The exact location of the defected finned tube should be detected by visually using borescope or other suitable manners.

2) Decide cutting length and quantity to be cut for making access space The cutting length and quantity should be decided base on workability

of the defected finned tube and recovering finned tubes that were cut it off for access.

3) Remove fins on the finned tubes to be cut off for access Minimum 100mm of fin should be stripped off as below figure. [Section View] 4) Cutting off the bare section of finned tubes using thin cutter The cutting of tubes should use portable electric cutting machine with

thin cutter to keep proper gap of butt weld. 5) Internal cleaning and capping of both ends of tubes As soon as cut off of tubes, both ends of tube internal shall be cleaned

Min. 100mm

Cutting point (Center of 100mm)

Defected finned tubeFinned tubes to be cut off for access

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by using vacuum cleaner or suitable manners and caped with plastic cap or vinyl tape to prevent inflow of foreign material during repair works.

6) Repair welding of the defected zone The defected zone can be repair welded directly for leaking area after

removal of defect and making a groove for repair welding, and also be rectified by inserting new piece of tube after cutting of proper length including defected area.

For the inserting new piece of tube, both end of tube and new piece should be weld prepared with 30°for butt welding.

Before repair welding, weld zone should be preheated in accordance

with applicable WPS considering material specification. The repair welding should be done by qualified welder in accordance

with relevant code.

Headroom for repair work should be min.800mm as picture below.

Picture showing worker welds at headroom 840mm.

PORTABLE WELDER (350W X 160H X 160T) TIG TORCH (45MM)

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Filler Metal (2~2.3mm)

Torch

100mm

Magnet Mirror

45mm

① ②

③ ④

Welding Sequence

START WELDING READY TO WELD

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7) Non-destructive examination The repair weld should be examined by radiographic test to verify the

soundness of welds. 8) PWHT PWHT depends on material specification. 9) Recovering of adjacent tubes which were cut off for access space The welding, NDE and PWHT should be done in accordance with above

clause 5) ~ 7). Each step of finned tubes shall be recovered consecutively considering NDE(RT).

4.2 Type-B : By replacing of the defected finned tube

For the applying this method, firstly surrounding circumstance such as casing wall structure, pipe lines and any other obstruction adjacent to the defected zone should be verified in order to insert new finned tube. The conception of rectification is to replace with new finned tube after making access opening on casing wall and taking out existing defected finned tube. New finned tube can be made several pieces, and it will be welded during inserting process if it is too long to handle the tube considering surrounding circumstance. Advantages for this method

- There is nothing to effect the reduction of heat transfer space Disadvantages for this method

- Rectification time will be taken longer than plugging method - Radiographic examination is required for butt weld - Some cases cannot apply this method due to surrounding circumstance

WELD AT 2ND ROW COMPLETE WELDING AT 2ND ROW

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Detail Rectification Sequence



2) The surrounding circumstance such as casing wall structure, pipe lines

and any other obstruction adjacent to defected zone should be verified in order to insert new piece of finned tube. As described in below figure, surrounding circumstance should be verified for both inside cavity and casing wall outside in order to insert it successfully.

Entire figure of HRSG is shown as attachment #1. 3) If there are no any obstructions to put new finned tube as like

mentioned above, make access opening window on casing wall (300mm x 300mm). The access opening window shall be located on same direction to tube longitudinal direction, and it can be made either of both front and rear casing wall considering accessibility and workability for tube inserting.

4) Removal of existing defected tube

Before removal of existing defected tube, adjacent U-bends or connection tubes which are obstructing to extract tube shall be cut off completely. The steel wire or rope shall be tied securely to end of tube to lead new piece of finned tube as like shown below figure.

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4.1) Case 1 : Pull out the defected tube only

4.2) Case 2 : Pull out the defected tube after cutting out tube of

interfered part

5) Insert new piece of finned tube Before inserting new piece of finned tube, special jig should be used in order to easily draw out to tube sheet zone as shown below figure. After that, new piece of finned tube should be drawn out slowly using rope which was lead in module internal during extracting the defected finned tube.

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6) Weld preparation and butt welding Both end of tube and connection tube shall be weld prepared for butt welding after internal cleaning. Before butt welding, weld zone should be preheated in accordance with applicable WPS considering material specification.

The repair welding should be done by qualified welder in accordance

with relevant code.

7) Non-destructive examination The butt welds should be examined by radiographic test to verify the

soundness of welds. 8) PWHT PWHT depends on material specification.

9) Recovering of casing opening which was made for access

4.3 Type-C : By plugging of the defected finned tube

The conception of rectification is to block the defected finned tube using plug for both headers. Advantages for this method

- Easy to rectify and take shorten time Disadvantages for this method

- The reduction of heat transfer space will be originated corresponding to the defected finned tube.

Tack Welding(6 Places)

New Finned Tube

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Detail Rectification Sequence



2) Cut off the tube of 100mm closely to header,

In order to block the header hole for both headers, the tubes which are connected with header shall be cut off approximately 100 mm from header out surface.

3) Insert plug in header hole and weld it for both headers After removal of debris or reinforcement of weldment, insert plug in header hole and weld it.

4) Non-destructive examination The plug welds should be examined by dye penetrant test to verify the

soundness of welds. 5) PWHT PWHT depends on material specification.

5.0 Hydrostatic Test

Hydrostatic test can be done respective equipment considering to location of the defected tube and systemic possibility. But this is not mandatory to perform it. This process will be decided according to client requirements or local regulation.

6.0 Documentation

After completion of rectification works, all inspection records should be submitted to client for approval.

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7.0 Application

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7.1 Module #1

1) Specification Tube line Comp. Tube Spec. Fin Spec. Remark

A~C RH-IP2 SA213-T91 /Φ44.5 x t2.6 A240TP409 / t1.0 x 13w

D~E SH-HP3 SA213-T91 /Φ31.8 x t4.0 A240TP409 / t1.0 x 15w

2) Rectification Type

Tube line Type Row No. = Max. length of replacing tube(m) P.O.D

A~E A N/A N/A

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7.2 Module #2


A~C RH-IP1 SA213-T11 /Φ44.5 x t2.6 A240TP409 / t1.0 x 13w

C~F SH-HP2 SA213-T91 /Φ31.8 x t3.0 A240TP409 / t1.0 x 15w



A~F A N/A N/A

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7.3 Module #3


A~L EV-HP SA210-C /Φ38.1 x t2.6 A1008CS / t1.0 x 13w

M~N SH-HP1 SA213-T11 /Φ31.8 x t3.0 A240TP409 / t1.0 x 15w



A~E A N/A N/A

F~J B 1~78=2.5 Front

K B 1~12=15 13~19=2.5 20~60=15 61~66=2.5 67~78=15 Front

L B 1~11=15 12~18=2.5 19~60=15 61~66=2.5 67~78=15 Front

H~L B 1~78=2.5 Rear

M~N B 1~78=8.5 Rear

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7.4 Module #4-1


A~L EC-HP2 SA210-C /Φ31.8 x t2.8 A1008CS / t1.0 x 15w

M~N SH-IP SA192 /Φ38.1 x t2.6 A1008CS / t1.0 x 15w



A~E A N/A N/A

M~N B 1~4=15

9~13=15 19~24=15

5~8=5.5 24~27=5.5 14~18=4.5 28~51=15 52~55=5.5

71~74=5.5 56~60=15 66~70=15 75~78=15

61~65=4.5 Front

F B 1~4=2.5 5~73=8 74~78=2.5 Rear

G B 1~4=2.5 5~75=8 76~78=2.5 Rear

H B 1~2=2.5 3~75=8 76~78=2.5 Rear

I B 1~2=2.5 3~77=8 78=2.5 Rear

J B 1~77=8 78=2.5 Rear

K~L B 1~78=8 Rear

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7.5 Module #4-2


A~B SH-LP SA192 /Φ38.1 x t2.6 A1008CS / t1.0 x 10w

C~H EV-IP SA192 /Φ38.1 x t2.6 A1008CS / t1.0 x 15w



A~E A N/A N/A

F B 1~17=8 18~24=2.5 25~54=8 55~62=2.5 63~78=8 Rear

G B 1~16=8 17~22=2.5 23~55=8 56~62=2.5 63~78=8 Rear

H B 1~15=8 16~22=2.5 23~56=8 57~64=2.5 65~78=8 Rear

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7.6 Module #5-1


A~J EC-HP1 =EC-IP

SA210-C /Φ31.8 x t2.8 SA192 /Φ31.8 x t2.6

A1008CS / t1.0 x 15w A1008CS / t1.0 x 15w



A~E A N/A N/A

F~J B 1~78=2.5 Front

F~J B 1~78=2.5 Rear

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7.7 Module #5-2


A~J EV-LP SA192 /Φ38.1 x t2.6 A1008CS / t1.0 x 15w



A~E A N/A N/A

F~J B 1~4=18

9~13=18 19~23=18

5~8=5.5 24~27=5.5 14~18=4.5 28~51=18 52~55=5.5

71~74=5.5 56~60=18 66~70=18 75~78=18

61~65=4.5 Front

F,H,J B 1~21=25 22~25=10 26~37=25 38~78=5 Rear

G,I B 1~21=25 22~24=10 25~37=25 38~78=5 Rear

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7.8 Module #6


A~N EC-PR SA192 /Φ31.8 x t2.6 A1008CS / t1.0 x 15w



A~E A N/A N/A

F B 1~4=18

9~14=18 21~23=18

5~8=5.5 24~27=5.5 15~20=2.5 28~51=18 52~55=5.5

71~74=5.5 59~64=2.5 56~58=18 65~70=18 75~78=18

Front

G B 1~4=18

9~13=18 20~23=18

5~8=5.5 24~27=5.5 14~19=2.5 28~51=18 52~55=5.5

71~74=5.5 60~65=2.5 56~59=18 66~70=18 75~78=18

Front

H B 1~4=18

9~12=18 19~23=18

5~8=5.5 24~27=5.5 13~18=2.5 28~51=18 52~55=5.5

71~74=5.5 61~66=2.5 56~60=18 67~70=18 75~78=18

Front

I B 1~4=18 9~11=18

19~23=18

5~8=5.5 18=5.5

24~27=5.5 12~17=2.5 28~51=18

52~55=5.5 61=5.5

71~74=5.5 62~67=2.5

56~60=18 68~70=18 75~78=18

Front

J B 1~4=18 9~11=18

19~23=18

5~8=5.5 17~18=5.5 24~27=5.5

12~16=2.5 28~51=18 52~55=5.5 61~62=5.5 71~74=5.5

63~68=2.5 56~60=18 69~70=18 75~78=18

Front

K B 1~4=18

9=18 19~23=18

5~8=5.5 16~18=5.5 24~27=5.5

10~15=2.5 28~51=18 52~55=5.5 61~63=5.5 71~74=5.5

64~68=2.5 56~60=18 69~70=18 75~78=18

Front

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L B 1~4=18

9=18 19~23=18

5~8=5.5 16~18=5.5 24~27=5.5

10~15=2.5 28~51=18 52~55=5.5 61~64=5.5 71~74=5.5

65~70=2.5 56~60=18 75~78=18 Front

M B 1~4=18 19~23=18

5~7=5.5 14~18=5.5 24~27=5.5

8~13=2.5 28~51=18 52~55=5.5 61~64=5.5 71~74=5.5

65~70=2.5 56~60=18 75~78=18 Front

N B 1~4=18 14=18

19~23=18

5~7=5.5 15~18=5.5 24~27=5.5

8~13=2.5 28~51=18 52~55=5.5 61~65=5.5 73~74=5.5

67~72=2.5 56~60=18

66=18 75~78=18

Front

F B

1~6=25 12~14=25

21=25 26~36=25

15~20=2.5 22~25=10 37~42=9

43=25 49~53=25 54~57=10

58~59=25 66~67=25 73~78=25

60~65=2.5 Rear

G B

1~6=25 12=25

19~20=25 25~36=25

13~18=2.5 21~24=10 37~42=9

43=25 49~53=25 54~57=10

58~59=25 66~67=25 73~78=25

60~65=2.5 Rear

H B

1~6=25 12=25

19~21=25 26~36=25

13~18=2.5 22~25=10 37~42=9

43=25 49~53=25 54~57=10 58~61=25

73~78=25 62~67=2.5 Rear

I B 1~6=25

17~20=25 25~36=25

12~16=2.5 21~24=10 37~42=9

43=25 49~53=25 54~57=10 58~61=25

73~78=25 62~67=2.5 Rear

J B 1~6=25

17~21=25 26~36=25

12~16=2.5 22~25=10 37~42=9

43=25 49~53=25 54~57=10 58~63=25

73~78=25 64~67=2.5 Rear

K B 1~6=25

16~20=25 25~36=25

12~15=2.5 21~24=10 37~42=9

43=25 49~53=25 54~57=10 58~63=25

73~78=25 64~67=2.5 Rear

L B 1~6=25

15~21=25 26~36=25

12~14=2.5 22~25=10 37~42=9

43=25 49~53=25 54~57=10 58~64=25

73~78=25 65~67=2.5 Rear

M B 1~6=25

14~20=25 25~36=25

12~13=2.5 21~24=10 37~42=9

43=25 49~53=25 54~57=10 58~65=25

73~78=25 66~67=2.5 Rear

N B 1~6=25

13~21=25 26~36=25

12=2.5 22~25=10 37~42=9

43=25 49~53=25 54~57=10 58~66=25

73~78=25 67=2.5 Rear

Legend P.O.D : Pull-out Direction N/A : Not Applicable

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Qurayyah CCPP HRSG

6.0 Precaution for HRSG Operating and Maintenance Doc.No :xxxxx Rev. -

6.0 PRECAUTION FOR HRSG OPERATING AND MAINTENANCE

6.1 General Precaution

6.2 Precautions During Operation

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6.0 Precaution for HRSG Operating and Maintenance Doc.No :xxxxx Page 1 of 7 Rev. -

6.0 PRECAUTION FOR HRSG OPERATING AND MAINTENANCE

6.1 General Precaution

6.1.1 Operating Data This HRSG has been designed to comply with specific technical requirements : pressure, temperature, flows, etc, in accordance with the Heat Balance Cases parameters. Therefore, the maximum operating parameters shall not be exceeded. The power plant personnel shall have a complete knowledge of the HRSG unit operation and shall be properly trained. By maintaining the heat transfer sections external surface clean, the temperature of the GT exhaust gas leaving the HRSG, as well as the related pressure drop (draft loss) through the HRSG, will normally be constant, for a given value of the GT exhaust gas input. Therefore, accurate performance records shall be kept, starting with the HRSG commissioning. Based on the HRSG unit "new and clean condition", set (standard) values must be determined. Any deviation from these set values will allow the evaluation of a satisfactory operation. Also, the deviations will indicate a potential or actual trouble (unsatisfactory operation), as soon as it occurs. The operator shall determine the correct cause of any trouble or discrepancy, between the set and actual values, in order to avoid the development of significant troubles. The operation records shall be properly kept. Their format shall allow an easy comparisons with similar operation conditions, as well as an easy interpretation. The main points to be measured and recorded are the following (but not limited to), as shown on the related P&IDs: 1. Section / component pressure 2. Section / component temperature 3. Drums water level 4. Feed water flow 5. Feed water quality

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Qurayyah CCPP HRSG


6. Steam purity 7. HRSG water and blowdown analysis

6.1.2 Evaporation Rate The steam flow shall be measured or estimated by using steam and/or water flowmeters. A blowdown allowance shall be considered if a water flowmeter only is used. The accuracy of the flowmeters shall be periodically checked. The pressure and/or temperature deviations, from the values for which the instrument was calibrated will introduce errors in the measuring accuracy. The superheater pressure drop will increase with evaporation rate increase.

6.1.3 Steam Purity The moisture content and the concentration of solids in the steam leaving the HRSG depend to a great extent on the feedwater quality. The alkalinity and concentration of dissolved and suspended solids can be maintained below predetermined values by using a correct feedwater treatment operation and an adequate blowdown procedure.

6.1.4 Safety Valves The primary purpose of the safety valves is to prevent excessive pressure in the HRSG and superheater. Safety valves, normally located on the steam drums and on the superheater outlet lines, are set to lift in sequence. There should be no obstructions at the safety valves inlet or outlet. The superheater is protected by setting the superheater safety valves to pop open prior to the safety valves on the steam drum.

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6.2 Precaution during Operation

6.2.1 Flue Gas Temperature

The flue gas temperature rises with an increase in the GT load and decreases with a load decrease. The flue gas temperature valves in relation to the load values shall be recorded. These records represent important data for normal operation and for abnormally high or low flue gas temperature situations which the operator shall notice immediately. Possible causes of abnormal flue gas temperature are as follow: 1) flue gas temperature is abnormally low :

A flue gas temperature abnormally low indicates that there is a low turbine exhaust gas temperature. In this case, the O2 content in the Combustion Turbine exhaust gas is extremely high, and the turbine shall be investigated accordingly.

2) flue gas temperature abnormally high : (1) Abnormally high percentage of excess air

Normally, the O2 content in the Combustion Turbine exhaust gas is at high levels. If the percentage of excess air is extremely high, special attention shall be provided. This occurs frequently, especially at Combustion Turbine excessive partial (low) loads.

(2) Heating surface contaminated with soot, if applicable.

6.2.2 Priming Generally, the drums water level shall be controlled to the normal water level specified in the steam drum section of this manual. Sudden fluctuations are not permitted. Priming (of humid steam) may occur when the HRSG is either subjected to a required evaporation rate at a pressure significantly lower than the normal operating or experiences a very high water level. HRSG drum capacity is large in comparison with the evaporation rate; however, priming can occur during the sudden load increase/ fluctuations.

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When high water level occurs, the feedwater control must be changed to "Manual", in order to reduce the flow of drum water, which requires the drum water level to be maintained at a low level. Therefore, a minimum water level must be maintained. If required, GT load may have to be reduced.

6.2.3 Superheater 1) Superheater safety relief valve operation

The superheater safety relief valve shall be set to operate at a pressure, which is lower than the drum safety relief valve set point. Therefore, when the steam rate decreases suddenly, or is reduced to zero, the superheater safety relief valve will operate to maintain flow through the superheater while protecting the superheater from over pressure. When the steam rate decreases, the operator shall identify immediately the reason, because the superheater safety valve is not designed to maintain the steam pressure within the prescribed limits, for an extended period of time.

2) Superheater damage prevention The most frequent damage that occur during the HRSG operation are generated by the superheater tubes bulging and warping, because of either improper control during the HRSG startup or shutdown, or HRSG continuous operation. Therefore, the operator shall consider the required precautions. When the temperature of flue gas passing through the superheater is high, the superheater tube wall temperature is 20~40℃ higher than the steam temperature inside the tube. Also, the boiler water capacity is lower than the boiler evaporation rate. Therefore, if the feed water control system is not properly monitored, fluctuations in the HRSG water level many occur. Appropriate measures should be taken to prevent the superheater damage, possible to occur during the HRSG operation. The HRSG operator should monitor the following occurrences in order to prevent the damage:

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(1) Incidents originating inside the superheater tube, (steam/side) scales carried with the HRSG steam moisture have the tendency to adhere to the interior side of the superheater tube and to accumulate, to build an excessively thick deposit. The heat resistance of this deposit will cause temperature rise of the superheater tube due to scales is it the result of “priming”. It is very important to always operate the HRSG within "the limit values of feed water and HRSG water" furnished by DHICO. The causes leading to priming are as follows: (a) The HRSG water limits, especially pH and dissolved solids content,

are excessively high, or oil and grease are mixed in the water (foaming).

(b) Large quantities of chemicals have been injected in the HRSG. (c) Feed water is extremely contaminated due to a failure of the water

treatment system. (d) Various plant heat exchangers drains or leakage, when connected

to the condensate - feed water systems can contaminate the water quality.

(e) HRSG operation at a pressure much lower than the specified pressure.

(f) Items (a) through (d) above refer to the feed water chemical components (high content) action on the HRSG priming. However, priming can also occur due to HRSG excessive high water level. Corrective action must be taken.

(g) HRSG water can be fed directly to superheater tubes without through of drum internal(separator and dryer) due to drum internals leakage. The result is similar with the priming result.

When intensively primed because above reasons, the superheater steam temperature will drop abruptly. When the HRSG experiences a slight priming, the steam temperature drop could be so small that it may not be noticed.

(2) Incidents originating outside superheater tubes (gas side).

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Generally, deposits of soot, etc., on the tubes external surface do not cause an excessive temperature rise of the superheater tubes temperature. However, when the flue gas flow is affected by such deposits, the superheater tubes may be overheated in the areas with an excessive temperature rise of the superheater tubes.

6.2.4 Steam Temperature

The superheater outlet steam temperature is generally little affected by load changes. 1) In the following case, superheater steam temperature rises abnormally and,

therefore, careful adjustment is required: (1) Too high temperature of GT exhaust gas.

2) In the following cases, superheated steam temperature falls abnormally and, therefore, careful adjustment is required: (1) Too low temperature of GT exhaust gas. (2) Excessive wet steam at superheater inlet. (3) Contamination of superheater tubes inside or outside. (4) Lower than normal steam pressure.

When boiler priming occurs, superheated steam temperature drops sharply and then rises again. The frequency and intensity of such variations of superheated steam temperature increases with the increase in total solid content or alkalinity of HRSG water.

6.2.5 Blowdown Procedure Blowdown is an important factor in the HRSG water control and has the following two objectives. 1) Prevents the concentration of impurities in the HRSG water. 2) Remove deposits from drum inside. # Objective No.1 During the HRSG operation, continuous blowdown shall be in operation, in order

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to maintain water quality in each HRSG drum. # Objective No.2 During the HRSG operation, intermittent blowdown shall be performed by rapidly blowing a certain quantity of HRSG water, under pressure, from the drum, at certain intervals of time. Normally, the intermittent blowdown shall be performed 1 to 3 times in 24 hours, in order to maintain the water chemistry. The blowdown shall be preferably performed during the HRSG shutdown to maintain as much heat as possible. The blowdown valves shall be periodically inspected for leakage.

6.2.6 Access to Stack

The access must be locked for personnel protection purpose considering emergency simple cycle operation.

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0 2011.07.16 First Issue BJ Park IS Kim SG Jung REV NO. DATE DESCRIPTION CHKD. CERT. APPD.

Project Title CONVERSION OF QURAYYAH OPEN CYCLE POWER

PLANT TO COMBINED CYCLE POWER PLANT PROJECT C

Client

Consultant

Contractor

Document Title

RECOMMENDED HRSG HYDROSTATIC TEST PRO.




THIS DOCUMENT IS NOT TO BE USED FOR CONSTRUCTION OR FOR ORDERING


APPROVAL/CERTIFICATION INFORMATION DOC.NO. REV.NO.

QURAYYAH SAUDI ARABIA JOB ORDER NO.

1-0923053.01 Job No. Project Subdivision Document Type Code Document number Revision

30621127 000 GAP EE-XXXXX 0

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Recommended HRSG

Hydrostatic Test Procedure Doc. Number Rev.0

QURAYYAH COMBINED CYCLE POWER PLANT EE-XXXXX PAG. 2 OF 22

TABLE OF CONTENTS

1.0 SCOPE OF HRSG HYDROSTATIC TEST

1.1 Introduction 1.2 HRSG Pressure Test Packages

2.0 PREPARATION FOR HYDROSTATIC TEST 2.1 Recommended Temporary Equipment for Test 2.2 HRSG Volume under the Hydrostatic Test 2.3 Estimate of Quantity of Hydrostatic Test Media 2.4 Requirements for Hydrostatic Test and Lay-Up Media 2.5 Temporary Piping

3.0 HYDROSTATIC TEST STEP 3.1 Preliminary Hydrostatic Test 3.2 Official Hydrostatic Test

4.0 PRESERVATION AFTER HYDROSTATIC TEST

5.0 HYDROSTATIC TEST PRESSURIZING CHART

6.0 ATTACHMENT 6.1 Hydro. Test Boundary for Package No.1 (HPSH/HPEVA/HPSTM Piping) 6.2 Hydro. Test Boundary for Package No.2 (HPECO/HPFWT Piping) 6.3 Hydro. Test Boundary for Package No.3 (RH/HRH,CRH Piping) 6.4 Hydro. Test Boundary for Package No.4 (IPSH/IPEVA/IPSH Piping) 6.5 Hydro. Test Boundary for Package No.5 (IPECO/IPFWT Piping) 6.6 Hydro. Test Boundary for Package No.6 (LPSH/LPEVA/LPSTM Piping) 6.7 Hydro. Test Boundary for Package No.7 (CPH/CPH Piping)

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1.0 SCOPE OF HRSG HYDROSTATIC TEST

1.1 Introduction

After installation of all HRSG pressure parts, Code/OEM requires that a HRSG shall be subjected to a hydrostatic pressure test. This will be conducted at a test pressure of 1.5 times the maximum allowable working pressure as on relevant OEM’ design documents/drawings.

This recommended procedure is applicable to the hydrostatic test for the pressure parts of HP, RH, IP, LP and CPH section for Heat Recovery Steam Generator(HRSG) of Qurayyah Combined Cycle Power Plant, Kingdom of Saudi Arabia.

This document only describes the general procedure for the hydrostatic pressure test of the HRSG. The detail description including method statements as well as health & safety instruction shall be developed by HRSG Erector based on the recommendation of this document

Purpose

The primary purpose of hydrostatic test is to provide a good quality of performance of HRSG before chemical cleaning and cold/hot commissioning operation prior to commercial services by detecting welding detects if have

Applicable Codes

a) ASME Section I

b) ASME B31.1

Responsibility

a) HRSG Erector is responsible for confirming and controlling the hydrostatic test job being carried out according to the approved procedure.

b) The responsible personnel (ex. mechanical site manager) in charge of hydrostatic test of HRSG must control overall working process in accordance with the approved procedure.

c) Temporary control office should be placed around the pressurization pump. The communication system for pressurization and depressurization shall be carried out by means of mobile wireless one.

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1.2 HRSG Pressure Test Packages

No System MAWP (barg)

Test Pressure (barg)

Remark

1 HPSH / HPEVA / HPSTM Piping 153 / 153 / 146 219 Note.2

2 HPECO / HPFWT Piping 210 315

3 RH / HRH Piping / CRH Piping 45 / 45 / 45.48 67.5 Note.2

4 IPSH / IPEVA / IPSH Piping 45.48 68.22

5 IPECO / IPFWT Piping 75 112.5

6 LPSH / LPEVA / LPSTM Piping 10 15

7 CPH / CPH Piping 40 60 Note

1) STM : Steam / FWT : Feedwater

2) Reference : ASME Interpretation I-89-68 issued dated on March 1, 1991

In principle, air vent pipes and drain pipes attached to the economizer, superheater, evaporator, and main piping shall be subjected to the hydrostatic test up to and including the respective 2nd block(isolation) valve.

The branch lines, such as the sampling, chemical injection lines, shall be also be hydrostatically tested, up to and including the respective 1st block(isolation) valve.

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2.0 PREPARATION OF HYDROSTATIC TEST

2.1 Recommended Temporary Equipment for Test

Temporary equipment, etc is to be provided sufficiently based on following table.

Equipment Specification Scope Remark

Water Filling Pump 50 t/h x 1 set HRSG Erector

Temporary

Pressurizing Pump 400 barg HRSG Erector

Temporary

400 barg Temporary Hand Pump (if necessary)

Air Compressor 7 barg HRSG Erector

On-site compressed service air may be used, but proper filtration is absolutely necessary

Pressurizing lines and valves

Complete set HRSG Erector

Temporary

Filling and blow-off lines and valves

Complete set HRSG Erector

Temporary

Pressure Gauges 400 bar x 2 250 bar x 2 100 bar x 2 30 bar x 2

HRSG Erector

Calibration is required

Blind cap and test plugs

All of test plugs except safety valves

HRSG Erector

If necessary

(Test gas for safety valves will be provided by OEM)

Water Storage Tank To have a capacity larger than the amount of HRSG water

HRSG Erector

Temporary

Note

The test medium for hydrostatic test shall be de-mineralized water to prevent corrosion of HRSG during the test period. The medium temperature must be no less than the ambient temperature, but in no case less than 21.1 oC as required by ASME Section I, PG-99 Hydrostatic test.

During the hydrostatic test, the medium shall be maintained above 21.1 oC.

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2.2 HRSG Volume under Hydrostatic Test

The following amount of volume are to be hydrostatic tested in HRSG scope. (per 1Unit)

HRSG Pressure Parts (Module & Link Piping)

Section Volume (cubic.m)

HP System 67.41

IP & RH System 59.8

LP System 30.7

Preheater System 16.0

Sum 173.9

HRSG Pressure Vessels


HP Drum 34.0

IP Drum 13.8

LP Drum 63.9

Deaerator 21.4

Sum 133.1

HRSG Piping with HRSG Scope


Condensate Piping 12.4

IP/LP Feedwater Piping 4.4

HP Feedwater Piping 4.1

LP Steam Piping 4.0

HP Steam Piping 5.9

IP & CRH Steam Piping 14.6

HRH Steam Piping 10.4

Sum 55.8

Total HRSG Hydrostatic Volume : 362.8 cubic.m

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2.3 Estimate of Quantity of Hydrostatic Test Media (per 1Unit)

Activity Package Water Amount (Ton)

Frequency Estimate Quantities (Ton)

Rinsing

Pre & Official Test

Package No.1 HPSH/HPEVA/ HPSTM Piping

72 4 288

Package No.2 HPECO / HPFWT Piping

40 4 160

Package No.3 RH / HRH,CRH Piping

56 4 224

Package No.4 IPSH/IPEVA/IPSH Piping

45 4 180

Package No.5 IPECO/IPFWT Piping

5 4 20

Package No.6 LPSH/LPEVA/LPSTM Piping

120 4 480

Package No.7 CPH / CPH Piping

29 4 116

Post Hydro Lay-up All Package from No.1 - 7

366 1 366

Total 1,834

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2.4 Requirements for Hydrostatic Test and Lay-up Media

The following are requirements for media used for hydrostatic test as well as for rinsing/flushing of HRSG components and piping systems.

Selection of the appropriate hydrostatic test, rinsing/flushing and post-hydro lay-up media ensures that components or piping systems do not sustain corrosion-induced damage and furthermore compliance with the specified water chemistry.

General Requirements

The components or piping systems shall be tested and/or preserved with water of equivalent or better quality than that used for normal HRSG operation. In general, the components and piping system (steam & water cycle of plan including HRSG) shall be tested with demineralized water of the best available quality where oxygen content shall be maintain as low as possible. The use of fill water, treated with solid chemicals, should be avoided. Deposits of solid materials in super heaters can be detrimental from heat transfer and corrosion standpoints.

Requirements for Hydrostatic Test Media

Demineralized water or Condensate - Appearances : clear, colorless, odorless - Conductivity (25oC) : < 5 uS/cm - Chloride (Cl-) : < 0.5 mg/kg

Requirement for Post Hydrostatic Test Lay-Up

Demineralized water or Condensate treated with Ammonia - pH : > 10 - Chloride (Cl-) : < 0.5 mg/kg - Ammonia : > 10 mg/kg

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2.5 Temporary Piping

1) Filing and blow-off lines

(a) HP Economizer

The filling and blow-off lines shall be connected to the feed water pipe line and header drain line.

(b) HP Evaporator and Superheater

The filling and blow-off lines shall be connected to the HP Evaporator supply pipe line and HP steam pipe line.

(c) IP Economizer

The filling and blow-off lines shall be connected to the feedwater pipe line and header drain line.

(d) IP Evaporator and Superheater

The filling and blow-off lines shall be connected to the IP Evaporator supply pipe line and IP steam pipe line.

(e) LP Evaporator and Superheater

The filling and blow-off lines shall be connected to the LP Evaporator supply pipe line and LP steam pipe line.

(f) CPH

The filling and blow-off lines shall be connected to the Condensate supply pipe line and header drain line.

2) Pressurizing line and location of sampling

The pressurizing lines shall be connected to the above related parts.

Notes:

1) Depending on the specific hydrostatic test methodology that the HRSG erector will issue, HRSG OEM can provide required advice in selecting the filling and blow-off lines, as well as the pressurizing lines and sampling location.

2) The third party inspector requirements(if have) shall also be considered by HRSG erector.

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3.0 HYDROSTATIC TEST STEP

3.1 Preliminary Hydrostatic Test

1) Water-filling

Water shall be introduced into the boiler.

NOTES :

Depending on the specific Hydrostatic Test methodology that the specialized contractor will issue, HRSG OEM can provide the required advice in selecting the filling lines.

The Third Party Inspector requirements shall also be considered by HRSG erector.

Fill with treated condensate or treated demineralized water. Refer to Section 2.4

CAUTION: The use of fill water, treated with solid chemicals, should be avoided. Deposits of solid materials in superheaters can be detrimental from heat transfer and corrosion standpoints. Superheaters containing stainless steel tubing are particularly vulnerable to stress corrosion cracking in the presence of such chemicals as caustic and chlorides.

2) Feed water system

HRSG feed water pump must be allowed to operate normally.

In case feed water system is not in service, HRSG Erector shall conduct water filling using a separate filling pump referred in section 2.0.

3) NDT

To confirm performing the Radiographic Examination and Stress Relieving Test to all pressure and welding parts.

4) Pipe Support

To check whether all the hanger supports are in locked condition.

5) Cleaning

Before starting to fill the boiler make sure all drums and headers are cleared of foreign material. Close all drains. Open all vents normally used when filling the HRSG (such as superheater link vents, economizer link vents, drum vents).

6) Operator and Inspector

Operators and inspectors are requested to be placed in the position as required.

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7) Pressurizing

Pressurizing shall be performed with the pressurizing pump, connected to the pressurizing line.

The pressurizing rate of 3∼5 bar per minute is recommended.

When the pressure has reached 80% of the safety valve setting pressure, the pressurizing pump must be stopped and the gags shall be set on the safety relief valves. Then, the pressurizing shall continue again, up to the test pressure.

8) Inspection

The HRSG shall be inspected for leakage 2-3 times during the pressurizing process. During the inspection, the pressurizing pump shall be shut-off. When the test pressure has been reached, the pressure shall be maintained for a minimum 10 minutes.

NOTES :

(a) close visual inspection is not required during this stage, in the interest of safety of the inspector.

(b) at near the design pressure(maximum working pressure), the pressurizing shall be performed at a lower rates, so as not to exceed the test pressure.

9) Pressure decreasing

After reaching the test pressure, the pressure is then reduced to design pressure using the relief valve of the pressurizing pump, special pressure relief valve or other drain valves.

NOTES :

(a) The pressure decreasing rate shall be 3-5 bar per minute.

(b) The pressure relief valve or drain valve must not be opened too fast.

When the pressure has decreased to design pressure, the pressure reducing valve must be closed, in order to carry out the official inspection for leakage. After inspection, pressure decreasing shall be continued.

When the pressure has decreased to 80% of the safety valve setting pressure, the pressure reducing valve must be closed, in order to remove the gags from the safety relief valves.

After the removal of the safety relief valve gags, the pressure decrease shall continue.

3.2 Official Hydrostatic Test

The HRSG shall be pressurized and depressurized in the same manner as in the preliminary test. The HRSG shall be maintained under the specified hydrostatic test pressure for required time

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The official leakage inspection shall be carried out at the design pressure during pressure decreasing stage..

If no leakage has identified, the hydrostatic test can be considered completed.

General Notes

The hydrostatic test shall be conducted using water at no less than ambient temperature, but in no case less than 21 oC as per PG-99.

At no time during the hydrostatic test shall any part of the boiler be subjected to a general primary membrane stress greater than 90% of its yield strength (0.2% offset) at test temperature as per PG-99.

The hydrostatic test pressure shall be under proper control at all times so that the required test pressure is never exceeded by more than 6% and close visual inspection for leakage is not required during this stage as per PG-99.1

It is recommended the boiler metal temperature shall be less than 49 oC during the close examination during the pressurizing status as per PG-99.2

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4.0 PRESERVATION AFTER HYDROSTATIC TEST

- Introduce nitrogen through the drum vent to pressure the unit to approximately 0.2~0.4 barg.

- Remove all hydrostatic test plugs and gags from the safety valves prior to starting up the unit

Note: Since there is generally some time delay between the hydrostatic test and the chemical cleaning of the boiler, the unit should remain full of water; air should not be allowed to enter.

Note: If there is a chance of freezing, the water in the drainable circuits can be displaced with nitrogen and the unit can laid up under nitrogen pressure. Temporary heating equipment should be provided to keep the non-drainable superheater elements above freezing temperature.

The preservation after the hydrostatic test shall be in accordance with the recommended HRSG Conservation Procedure.

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5.0 HYDROSTATIC TEST PRESSURIZING CHART

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5.1 Package No.1, HPSH / HPEVA / HPSTM Piping

Holding Time Min. 10 Minutes at 219 barg

Inspection Time Min. 10 Minutes at 146 barg

Safety Valve Gagging at ca. 108 barg

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5.2 Package No.2, HPECO / HPFWT Piping



Safety Valve Gaggingat ca. 168 barg

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5.3 Package No.3, RH / HRH, CRH Piping

Holding Time Min. 10 Minutes at 67.5 barg


Safety Valve Gaggingat ca. 29.5 barg

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5.4 Package No.4, IPSH / IPEVA / IPSH Piping


Inspection Time Min. 10 Minutes at 45.5 barg


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5.5 Package No.5, IPECO / IPFWT Piping




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5.6 Package No.6, LPSH / LPEVA, LPSTM Piping




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Recommended HRSG



5.7 Package No.6, CPH / CPH Piping




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6.0 ATTACHMENT

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텍스트 상자

SEE TO PACKANGE NO.1 PART2 DWG

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REFER TO BOP PACKAGE DWG

h113496

텍스트 상자


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HRSG HYDROSTATIC TEST PACKAGE NO.1 - PART1 HPSH SECTION

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SEE TO PACKAGE NO.1 PART1 DWG

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HRSG HYDROSTATIC TEST PACKAGE NO.1 - PART2 HPEVA SECTION

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HRSG HYDROSTATIC TEST PACKAGE NO.2 HPECO SECTION

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REFER TO PACKAGE NO.4 DWG

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SEE TO BOP PACKAGE DWG

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HRSG HYDROSTATIC TEST PACKAGE NO.3 HR SECTION

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텍스트 상자

SEE TO PACKAGE NO.

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HRSG HYDROSTATIC TEST PACKAGE NO.4 IPSH/IPEVA SECTION

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HRSG HYDROSTATIC TEST PACKAGE NO.5 IPECO SECTION

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HRSG HYDROSTATIC TEST PACKAGE NO.6 LPSH/LPEVA SECTION

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HRSG HYDROSTATIC TEST PACKAGE NO.7 - PART.1 CPH SECTION

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SEE TO PACKAGE NO.7 PART.2 DWG

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SEE TO PACKAGE NO.7 PART.1 DWG

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HRSG HYDROSTATIC TEST PACKAGE NO.1 - PART.2 CPH SECTION

0 2011.08.26 First Issue BJ Park IS Kim SG Jung

REV NO. DATE DESCRIPTION CHKD. CERT. APPD.

Project Title CONVERSION OF QURAYYAH OPEN CYCLE POWER

PLANT TO COMBINED CYCLE POWER PLANT PROJECT C

Client

Consultant

Contractor

Document Title

RECOMMENDED HRSG LAYUP PROCEDURE




THIS DOCUMENT IS NOT TO BE USED FOR CONSTRUCTION OR FOR ORDERING


APPROVAL/CERTIFICATION INFORMATION

DOC.NO. REV.NO.

QURAYYAH SAUDI ARABIA JOB ORDER NO.

1-0923053.01 Job No. Project Subdivision Document Type Code Document number Revision

30621127 000 GAP EE-XXXXX 0

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Layup Procedure Doc. Number Rev.0


TABLE OF CONTENTS

1.0 GENERAL

2.0 SELECTION OF LAYUP METHODS

3.0 DRY LAYUP METHOD

4.0 WET LAYUP METHOD

4.1 Hot Wet Layup Method 4.2 Cold Wet Layup Method

5.0 MONITORING

6.0 MISCELLANEOUS RECOMMENDATIONS

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1.0 GENERAL

The purpose of layup is to minimize corrosion (pit corrosion or oxygen pitting) as well as to reduce the subsequent start up after shutdown.

This procedure is for water and steam side, not for gas side. For gas side, refer to chapter 6 miscellaneous recommendation in this procedure.

There are three kinds of key factors for corrosion such as the water, the oxygen and the metal. In case of the metal, it is unavoidable in HRSG. There are two choices which are to eliminate water or oxygen. If remove water, it is dry layup method and if remove oxygen, it is wet layup method.

a) Dry Layup method

b) Wet Layup method

The concept of dry layup is to fully fill the nitrogen at the inside of tubes, pipes and drums.

The concept of wet layup is to fully fill the water with pH 10 ~ 11 and a low conductivity uniformly throughout the inside of tubes, pipes and drums.

All chemicals herein should be followed the manufacturer’s instructions.

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2.0 SELECTION OF LAYUP METHODS

Desiccant method can be used for transportation before install on site.

If delay starting of erection, it needs to discuss with DOOSAN.

During erection, it should be considered the attack by corrosion environments such as rainy.

After mechanical completion in field, it shall the hydro pressure test in field in accordance with hydrostatic pressure test procedure. Before hydro test and after hydro test, it shall follow layup method on hydro pressure test procedure.

After chemical cleaning, HRSG shall be conserved wet or dry layup method depending on the site conditions such as the below maintenance, freezing and availability.

There are many factors to select layup method to protect the HRSG heat transfer internal surfaces:

Maintenance

If expect maintenance during the outage, it shall select dry layup method. However, if maintenance is anticipated, the dry air method shall be used.

Freezing

If expect freezing during the outage, it shall select dry layup method.

Availability

If expect not to be operated properly the chemistry, it shall select dry layup method.

Outage period

If expect the subsequent start up during the outage, it shall select wet layup method.

Because HRSG can not be successfully dried, wet layup method is strongly recommended.

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3.0 DRY LAYUP METHOD

The Dry Layup method, which requires nitrogen sealing, is a typical and effective method used for a long outage period (more than 48 hours).

The following are mandatory requirements for the nitrogen gas sealing method:

a) After the HRSG pressure has reached the 1.5 barg, the water existing in the HRSG shall be gradually drained by opening the blow off valves.

b) The heat remaining in the HRSG metal will dry the moisture at the inside of tubes. Due to this reason, the vent is to open and to close. It must be initiated around 1.5 barg.

c) Charge nitrogen gas from nitrogen gas injection system of each drum.

d) When nitrogen gas, instead of water, starts to come out from the blowdown tank outlet (to the sump), drums blow off valves shall be closed.

e) After all HRSG sections have been filled with nitrogen gas, all valves shall be closed.

f) The nitrogen pressure in all sections shall be maintained at 0.5 barg (min. 0.2 barg). Nitrogen gas shall be recharged when the pressure reaches 0.3 barg. The nitrogen gas pressure in all sections shall be checked with the related existing pressure gauges.

g) Nitrogen gas pressure shall be checked daily at the pressure gauges.

h) As the HRSG cools to the ambient temperature, the nitrogen gas pressure shall be checked frequently because HRSG cooling will decrease nitrogen pressure.

Alternatively, the circulating dehumidified air is able to use instead of nitrogen under maintaining below 30% related humidity.

Maximum 0.1% volume percentage nitrogen is recommended.

Caution: Nitrogen is a hazard to personnel and can not be used if maintenance on the systems is going to be proceeded. If there are any leaks from the inside of tubes and piping to the gas side, anyone on the gas side of HRSG should be left because of a lethal environment.

If repair works are anticipated, dry air instead of nitrogen has to inject to the inside of tubes and piping. The related humidity levels should be checked at the drain or vent less than 30%.

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4.0 WET LAYUP METHOD

4.1 Hot Wet Layup Method

It is “bottle up” by closing stack damper and drain/vent valve.

The water chemistry shall be kept from the normal value to maximum value.

If the pressure in drum is less than 1.5 barg, it needs to fill nitrogen from steam drum to superheater to preventing air ingress into the inside of tubes, piping and drums.

The following are mandatory requirements for the hot wet layup method:

a) Keep drum level from start up level to normal level.

b) The temperature will gradually down by heat loss.

c) The pressure will be up and down for the time being and then it will gradually down.

If the pressure in drum approaches to 1.5 barg, the followings are mandatory requirements.

d) If the pressure approaches to 1.5 barg, the steam drum pressure shall be pressurized by nitrogen on the connection of steam drum.

e) Nitrogen gas pressure shall be maintained at 0.3 barg at any time.

f) Close the nitrogen connections until start up HRSG. Also, close the level gages on the steam drums if lasts over 3 days layup.

g) Before put in service, the drain valves are opened to blow off any water. Also, open the level gages.

Caution: Nitrogen is a hazard to personnel and can not be used if maintenance on the systems is going to be proceeded. If there are any leaks from the inside of tubes and piping to the gas side, anyone on the gas side of HRSG should be left because of a lethal environment.

4.2 Cold Wet Layup Method

The wet layup method requires the HRSG, except the superheater, to be completely filled with feedwater.

The wet layup method, which requires nitrogen sealing in superheater and which requires water sealing in evaporator / economizer, is a typical and effective method used for a long

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outage period (more than 48 hours).

The following are mandatory requirements for the Wet Layup method:

a) When the HRSG is required to be shutdown, the chemicals shall be added 30 minutes before taking the HRSG out of service.

b) The water quality shall be the same or similar to normal deaerated feedwater/condensate treated with chemicals. The recommended chemicals are hydrazine (or an alternative) for eliminating oxygen and ammonia(or amine) for maintaining pH value between 10 ~ 11.

c) Keep drum level from start up level to normal level.

d) The temperature will gradually down by heat loss.

e) The pressure will be up and down for the time being and then it will gradually down.

f) If the pressure approaches to 1.5 barg, the steam drum pressure shall be pressurized by nitrogen on the connection of steam drum.

g) Purge the superheater. The nitrogen shall be vented downstream the superheater.

h) After the HRSG complete filling, all valves shall be closed, to avoid any air flow into the HRSG sections

i) Nitrogen gas pressure shall be maintained at 0.3 barg at any time.

j) The hydrazine (or an alternative) concentration in the HRSG water shall be tested weekly. The chemical sampling system should be used for these tests. Hydrazine (or an alternative) shall be added, as required, to maintain the proportion of 100 to 200 ppm.

k) HRSG water level shall be checked. If required, additional feedwater shall be filled in. Also, hydrazine (or an alternative) shall be filled in, in order to maintain the required proportion.

l) Close the nitrogen connections until start up HRSG. Also, close the level gages on the steam drums if lasts over 3 days layup.

m) During wet layup, the recirculation of fluid is required for maintaining the chemicals intended every week for one hour. The temporary layup recirculation pump shall be connected to the evaporator downcomer and economizer inlet.

n) If not action l), drain the water under 0.3 barg of nitrogen pressure and refill the economizer and evaporator up to drum level high high with deaerated water, pH 10~11, hydrazine (or an alternative) concentration 200 ppm.

o) Before put in service, the drain valves are opened to blow off any water. Also, open the level gages.

The Requirement for Post Hydrostatic Test Layup

Demineralized water or Condensate treated with Ammonia

- pH : > 10

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- Chloride (Cl-) : < 0.5 mg/kg

- Ammonia : > 10 mg/kg

Caution : Nitrogen is a hazard to personnel and can not be used if maintenance on the systems is going to be proceeded. If there are any leaks from the inside of tubes and piping to the gas side, anyone on the gas side of HRSG should be left because of a lethal environment.

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5.0 MONITORING

Short term layup (four days) is required to monitor four hours basis and long term layup (over four days) is required to monitor every day basis.

DRY LAYUP

It should be monitored nitrogen pressure.

.

WET LAYUP

It should be monitored pH, conductivity and nitrogen pressure.

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6.0 MISCELLANEOUS RECOMMENDATIONS

At the beginning of the "Lay Up" method, the combustion gas side shall also be inspected.

Soot, etc. must be removed. The surface of the drums, tubes and the combustion gas side should be inspected for corrosion.

Gas side corrosion typically occurs when moist air is present with tube deposits containing sulfuric acid or other fuel-borne contaminants. The gas side can only be laid up dry, if necessary Electrical Heaters will be used to prevent condensate. And also silica gel can be placed inside the gas side. The quantities are 0.5 kg / m3. Periodic inspection of the gas side should be performed to ensure that conditions promoting rapid corrosion are not present. Under warm high humidity environment below the ambient dew point, a rust / flaky scale in finned tube will occur. The desired relative humidity is less than 30%.

If find the gas side corrosion, cleaning of flaky deposits from finned tubes is recommended.

- END OF DOCUMENT -

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9.0 HRSG Water Chemistry Requirements Doc.No :xxxxx Page 1 of 9 Rev. -

9.0 HRSG WATER CHEMISTRY REQUIREMENTS

9.1 General 9.2 Water Treatment 9.3 Requirement for HRSG Feedwater 9.4 Requirement for HRSG Drum Water (Boiler Water) 9.5 Requirement for Steam Quality (Reference) 9.6 Sampling/Monitoring Recommendation 9.7 Caution

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9.0 HRSG WATER CHEMISTRY REQUIREMENTS

9.1 General

The purpose of this requirement is to minimize corrosion, erosion and deposits under good industry practices. In order to protect all components of the steam water cycle against corrosion, erosion and deposits and so not to affect the plant efficiency, it is essential to control the water chemistry within the values in this requirement. This requirement is limited to drum type HRSG. Copper-tubed condenser, brass-tubed condenser and air cooled condenser is not permitted to use this requirement. These requirements are generally in accordance with published guidelines from EPRI, VGB, EN, ASME and ABMA. The plant water chemistry control requirements provided by plant engineering company are preferred. The aim of minimizing corrosion / erosion and avoiding deposits is reached by - Using de-mineralized water - Controlling the pH value by ammonia - Reducing the oxygen content within recommended ranges - Blowing off the drum water During normal operation, the maximum rate of make up water is one percentage. During upset condition, up to five percentage of make up water is allowed. Special attention is required when HRSG is in use for cogeneration purposes because of a wide range of make up water demand. During commissioning, this requirement should be verified by the plant operator. Generally, the quality of the steam is proportional to the quality of the water. Due to frequently start up and shut down, well skilled chemical operators are required.

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9.2 Water Treatment

HRSG OEM is not responsibility for water treatment. The type of chemical treatment will be selected depending on the variety of material, system supplied, etc. This requirement is to provide based on all volatile treatment. pH value is high enough so that any copper containment at the feed water system is not allowed. If there is any copper containment, oxygenated treatment can be selected under high purity water, lower pH value. Organic treatment chemicals is not permitted in order to minimize the potential flow accelerated corrosion.

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9.3 Requirement for HRSG Feedwater

The feedwater is from out of our boundary such as steam turbine condenser or external deaerator storage tank. The feedwater is pumped to HP/IP drums by the feedwater pump from LP storage tank. The feedwater is used to spray system. The following requirements are valid for continuous operation. During start up and shutdown, the following requirements will deviate. The following

requirements are the maximum allowable values except pH.

Parameter Unit Required

value

Cation conductivity @ 25deg. C μS/cm < 0.2

pH-value @ 25deg. C *1) - 9.4 ~ 9.8

Silica as SiO2 @ 25deg. C ppb < 20

Iron as Fe @ 25deg. C ppb < 20

Sodium as Na @ 25deg. C ppb < 10

Copper as Cu @ 25deg. C ppb < 3

Oxygen @ 25deg. C ppb < 10

TOC ppb < 100 In terms of pH, volatile alkalizing agents are strongly recommended achieving. Ammonia is a typical chemical. In terms of copper, copper containments in feedwater system is not allowed. It should be required to monitor cation conductivity and sodium content of feedwater in order to detect condenser leakage. In terms of oxygen, an oxygen scavenger is strongly not recommended up to 10 ppb of oxygen. The water quality of feedwater is very importance because of direct impact on steam purity.

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All volatile treatment is strongly recommended, especially once through HRSG. During start up and transient condition, the chemicals is required to stable the water and steam quality in this requirements. The chemical feeding can be stopped and then the plant converts to all volatile treatment.

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9.4 Requirement for HRSG Drum Water (Boiler Water)

The drum water is within circulation HRSG by natural or forced. The following requirements are valid for continuous operation. During start up and shutdown, the following requirements will deviate. The following requirements are the maximum allowable values except pH.

Parameter Unit Required value HP IP/LP Specific conductivity @ 25deg. C μS/cm < 30 < 50

pH Value @ 25deg. C - 9.4 ~ 9.8 9.4 ~ 9.8 Phosphate, PO4 @ 25deg. C ppm < 6 < 6 Silica as SiO2 @ 25deg. C ppm < 2 < 7

In terms of specific conductivity and silica, blowdown is a general method to divert. In terms of pH, volatile alkalizing agents are strongly recommended achieving the above requirement. All volatile treatment is suitable. Phosphate or caustic treatment may suffer from under deposit corrosion. The duct burner firing at the upstream of evaporator results in dry out locally concentrate the solid alkalizing agent by phosphate or caustic treatment and subsequently attack the corrosion. During start up and upset conditions, phosphate or caustic treatment can be used as an advantage from buffering characteristic. When HRSG water and steam quality is stable under the matching to this requirement, phosphate or caustic treatment can be stopped and converts to all volatile treatment.

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9.5 Requirement for Steam Quality (Reference)

The steam is admitted to the turbine. The following requirements are valid for continuous operation. During start up and shutdown, the following requirements may deviate. The following are just reference guideline only and project specific requirement for steam quality shall be came from steam turbine OEM.

Parameter Unit Required value

Cation conductivity @ 25deg. C μS/cm < 0.2 Silica as SiO2 @ 25deg. C ppb < 20 Iron as Fe @ 25deg. C ppb < 20 Sodium as Na @ 25deg. C ppb < 5 Copper as Cu @ 25deg. C ppb < 3

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9.6 Sampling/Monitoring Recommendation

The water chemistry should be monitored on-line basis. It should be required to monitor cation conductivity and sodium content of feedwater in order to detect condenser leakage. Typical sample points should be included, - Feedwater line - Evaporator The followings are measured by online or grab for trouble shooting. - Caution conductivity - pH - Sodium - Iron The length of sampling line should be kept as short as to avoid complications of time difference on sampling point and analyzer. It can be accommodated in the control loops.

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9.7 Caution

9.7.1 Copper Deposits

Copper alloys at the upstream of feed water inlet are not permitted. All ferrous metallurgy should be specified for feed water system including condenser, piping and valve. When copper components are present in the condenser and feedwater system, it should be noted and then it should be adjusted pH and chemicals under the specialist’s responsibility.

9.7.2 Hide Out When select the phosphate treatment on drum water, over feeding of phosphate during start up and shut down is reacting with magnetite on the tube and that phosphate gouging is a potential possibility. Especially, phosphate is not permitted to feed during duct burner firing because of increasing heat flux on HP evaporator.

9.7.3 FAC Key parameters for FAC are pH, temperature, oxygen concentration, fluid velocity and flow geometry. It is known that LP evaporator bend tube and LP drum internal and LP evaporator upper header are susceptible for FAC in case of low pH conditions, low oxygen level of drum water. 9.4 to 9.8 of pH value should be maintained to prevent FAC. The reducing type of oxygen scavenger should be prohibited under less than 10 ppb of oxygen content. - End of Document -

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Chapter 10 Operating Procedure Doc.No :xxxxx Rev. -

1 HRSG OPERATION DESCRIPTION This section describes operating procedures of the Heat Recovery Steam Generator (HRSG) for Qurayyah Combined Power Plant. They include the proper operating sequences for the HRSG and auxiliary equipment furnished. Refer to the relevant Piping and Instrumentation Diagram. Because the steam generator is only one part of the power plant, and all equipment must operate in unison, specific procedures and detailed values for the equipment not furnished are not included in this document. As operating experience is gained and the controls are fine-tuned, the characteristics and operating requirements of the unit will become apparent.

1.1 Completion of maintenance prior to operation

Check the HRSG to make sure that all maintenance work has been completed, all tools and debris have been removed, the handhole plates and manhole covers have been installed and secured, and all access doors have been installed and secured.

Check all relevant clearance certificates to be obtained and all work permits cancelled and signed out.

Check the safety valves to see if the gags have been removed, the lifting levers have been replaced, and the valves are not fouled or hung up.

1.2 Initial filling

This section describes the recommended procedure for filling an empty HRSG with water. If the unit is hot, the unit has to be cooled first to avoid severe temperature strains (Max. allowable temperature difference is approximately 50 deg.C). Also, since deposits of solids in a superheater can cause corrosion or inhibit heat transfer, introduction of solids by carryover of boiler water from the drum during filling should be avoided.

Reference P&ID ; P&I Diagram – HRSG H.P Superheater Section [Dwg No. EA-685640] P&I Diagram – HRSG Reheater Section [Dwg No. EA-685641] P&I Diagram – HRSG H.P Econ. & Evap. Section [Dwg No. EA-685642] P&I Diagram – HRSG I.P Section [Dwg No. EA-685643] P&I Diagram – HRSG L.P Section [Dwg No. EA-685644] P&I Diagram – HRSG Condensate Preheater Section [Dwg No. EA-685645]

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Description Section Action

1. Precautions All 1. All instruments should be lined up for service.

2. All power-operated valves should be lined up.

3. All equipment should be lined up.

4. Align position of all manual valves as shown in HRSG P&IDs.

5. Align HP/IP/LP section Auto. Valves as shown on the column labeled “START UP” listed in the table 1, 2 and 3.

Note; The activity of initial filling require manual action from local or control room.

2. Ready for LP drum filling

LP Open and prepare the following valves for filling.

1. Confirm closed condensate stop MOV (LCA-90-AA-001).

2. Place the position of CPH 3-way valve (LCA-90-AA-081), full open to CPH direction.

3. Open CPH Recirculation line TCV (LCA-94-AA-081).

4. Open CPH inlet and outlet line vent valves (LCA-90-AA-501/502, LCA-91-AA-501/502).

5. Open CPH Recirculation pumps outlet line vent valves (LCA-92-AA-501/502, LCA-93-AA-501/502).

6. Open Deaerator vent MOV (HAD-97-AA-001)

7. Open LP drum vent valves (HAH-97-AA-501/502).

3. Ready for IP drum filling

IP Open and prepare the following valves for filling.

1. Open IP feedwater small stop MOV (LAB-94-AA-002) and Close main stop MOV (LAB-94-AA-001).

2. Open IP Econ. Inlet and outlet line vent valves (LAB-94-AA-501/502, HAC-94-AA-501/502).

3. Open IP drum vent valves (HAH-94-AA-501/502).

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4. Ready for HP drum filling

HP Open and prepare the following valves for filling.

1. Open HP feedwater small stop MOV (LAB-90-AA-002) and Close main stop MOV (LAB-90-AA-001).

2. Open HP Econ. Inlet and outlet line vent valves (LAB-90-AA-501/502, HAC-90-AA-501/502).

3. Open HP drum Low load LCV isolation MOV (HAC-90-AA-002).

4. Open HP drum vent valves (HAH-90-AA-501/502).

5. LP drum filling

LP 1. Initial water filling is done by separate filling line from the demineralized transfer pump. The filling line is prepared in the condensate line. The filling from the demi. Water pump is only used for initial filling (System is in empty case). In case of normal start up, which mean the system is already filled by water, the demi. water pump will not be used.

Open the initial filling line isolation valves (LCA-95-AA-101/102)

♠ Close it after water fill completed.

2. Adjust the water flow about 10% of MCR flow by LP drum LCV (LCA-91-AA-081).

3. Close following valves when water overflow through vent line

- CPH inlet and outlet line vent valves (LCA-90-AA-501/502, LCA-91-AA-501/502).

- CPH Recirculation pumps outlet line vent valves (LCA-92-AA-501/502, LCA-93-AA-501/502).

4. Fill LP drum until Low Start up water level (-100 mm from Drum Center Line) has been reached.

♠ Do not overfill the drum

5. Close LP drum vent valves (HAH-97-AA-501/502) after water fill completed.

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6. IP drum filling

IP 1. Initial water filling is done by separate filling line from the demineralized transfer pump. The filling line is prepared in the feedwater pump IP discharge line (Refer to BOP P&ID-Feedwater System dwg.no. EA-682805-003). The filling from the demi. Water pump is only used for initial filling (System is in empty case). In case of normal start up, which mean the system is already filled by water, the demi. water pump will not be used.

Open the initial filling line isolation valves (LAB-45-AA-136/137)


2. Adjust the water flow about 10% of MCR flow by IP drum LCV (HAC-94-AA-081).

3. Close IP Econ. Inlet and outlet line vent valves (LAB-94-AA-501/502, HAC-94-AA-501/502) when water overflow through vent line.

4 Fill IP drum until Low Start up water level (-450 mm from Drum Center Line) has been reached.


5. Close IP drum vent valves (HAH-94-AA-501/502) after water fill completed.

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7. HP drum filling

HP 1. Initial water filling is done by separate filling line from the demineralized transfer pump. The filling line is prepared in the feedwater pump HP discharge line (Refer to BOP P&ID-Feedwater System dwg.no. EA-682805-002). The filling from the demi. Water pump is only used for initial filling (System is in empty case). In case of normal start up, which mean the system is already filled by water, the demi. water pump will not be used.

Open the initial filling line isolation valves (LAB-45-AA-134/135)


2. Adjust the water flow about 10% of MCR flow by Low load HP drum LCV (HAC-90-AA-082).

3. Close HP Econ. Inlet and outlet line vent valves (LAB-90-AA-501/502, HAC-90-AA-501/502) when water overflow through vent line.

4. Fill HP drum until Low Start up water level (-550 mm from Drum Center Line) has been reached.


5. Close HP drum vent valves (HAH-90-AA-501/502) after water fill completed.

Table 1 – Auto. Valve Alignment; High Pressure Section

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Note. ; All manual valves position to be aligned per P&IDs Ref. HRSG

P&ID Valve Number Valve Description Start Up

Normal

Operation

Secure

To Warm

H.P Econ. &

Evap. Section

[EA-685642]

LAB-90-AA-001 HP Feedwater main stop MOV Auto(Open) Auto(Open) Auto(Close)

“ LAB-90-AA-002 HP Feedwater small stop MOV Auto(Close) Auto(Close) Auto(Close)

“ HAC-90-AA-002 HP Drum low load LCV isolation

MOV Auto(Close) Auto(Open) Auto(Close)

“ HAC-90-AA-082 HP Drum low load LCV Auto(Close) Auto Auto(Close)

“ HAC-90-AA-001 HP Drum Full load LCV isolation

MOV Auto(Close) Auto(Open) Auto(Close)

“ HAC-90-AA-081 HP Drum Full load LCV Auto(Close) Auto Auto(Close)

“ HAD-91-AA-002 HP Drum C.B.D MOV Auto(Close) Auto(Open) Auto(Close)

“ HAD-91-AA-001 HP Drum I.B.D MOV Auto(Close) Auto(Close) Auto(Close)

H.P

Superheater.

Section

[EA-685640]

HAH-91-AA-001 HP SH 1 inlet drain MOV Auto(Close) Auto(Close) Auto(Close)

“ HAH-90-AA-001 HP SH 2 drain MOV Auto(Close) Auto(Close) Auto(Close)

“ LBA-90-AA-001 HP SH 3 drain MOV Auto(Close) Auto(Close) Auto(Close)

“ LBA-90-AA-005 HP steam line drain MOV Auto(Close) Auto(Close) Auto(Close)

“ LBA-90-AA-002 HP start up vent MOV Auto(Close) Auto(Close) Auto(Close)

“ LBA-90-AA-004 HP steam small stop MOV Auto(Close) Auto(Close) Auto(Close)

“ LBA-90-AA-003 HP steam Main stop MOV Auto(Close) Auto(Open) Auto(Close)

“ LAE-90-AA-001 HP DESH. Spray block MOV Auto(Close) Auto Auto(Close)

“ LAE-90-AA-081 HP DESH. Spray TCV Auto(Close) Auto Auto(Close)

“ LAE-90-AA-002 HP DESH. Spray Bypass MOV Auto(Close) Auto(Close) Auto(Close)

-End-

Table 2 – Auto. Valve Alignment; Intermediate Pressure Section Note. ; All manual valves position to be aligned per P&IDs

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Ref. HRSG


Normal

Operation

Secure

To Warm

I.P Section

[EA-685643] LAB-94-AA-001 IP Feedwater main stop MOV Auto(Open) Auto(Open) Auto(Close)

“ LAB-94-AA-002 IP Feedwater small stop MOV Auto(Close) Auto(Close) Auto(Close)

“ HAC-94-AA-001 IP Drum LCV bypass MOV Auto(Close) Auto(Close) Auto(Close)

“ HAC-94-AA-081 IP Drum LCV Auto(Close) Auto Auto(Close)

“ HAD-95-AA-002 IP Drum C.B.D MOV Auto(Close) Auto(Open) Auto(Close)

“ HAD-95-AA-001 IP Drum I.B.D MOV Auto(Close) Auto(Close) Auto(Close)

“ LBA-95-AA-003 IP steam line drain MOV Auto(Close) Auto(Close) Auto(Close)

“ LBA-95-AA-001 IP start up vent MOV Auto(Close) Auto(Close) Auto(Close)

“ LBA-95-AA-081 IP steam PCV Auto(Close) Auto(Open) Auto(Close)

“ LBA-95-AA-002 IP steam stop MOV Auto(Open) Auto(Open) Auto(Close)

Reheater

Section

[EA-685641]

LBC-90-AA-001 CRH steam stop MOV Auto(Close) Auto(Open) Auto(Close)

“ LBC-90-AA-002 CRH steam line drain MOV Auto(Close) Auto(Close) Auto(Close)

“ HAJ-90-AA-001 Reheater drain MOV Auto(Close) Auto(Close) Auto(Close)

“ LBB-90-AA-002 HRH steam line drain MOV Auto(Close) Auto(Close) Auto(Close)

“ LBB-90-AA-001 HRH start up vent MOV Auto(Close) Auto(Close) Auto(Close)

“ LBB-90-AA-081 HRH start up vent PCV Auto(Close) Auto(Close) Auto(Close)

“ LAF-90-AA-001 RH DESH. Spray block MOV Auto(Close) Auto Auto(Close)

“ LAF-90-AA-081 RH DESH. Spray TCV Auto(Close) Auto Auto(Close)

“ LAF-90-AA-002 RH DESH. Spray Bypass MOV Auto(Close) Auto(Close) Auto(Close)

-End-

Table 3 – Auto. Valve Alignment; Low Pressure Section Note. ; All manual valves position to be aligned per P&IDs

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Ref. HRSG


Normal

Operation

Secure To

Warm

Condensate

Preheater

Section

[EA-685645]

LCA-90-AA-001 Condensate stop MOV Auto(Open)(*) Auto(Open) Auto(Close)

“ LCA-90-AA-081 CPH 3-way valve

Auto(Open to

bypass

direction)

Auto Auto(In place)

“ LCA-94-AA-081 CPH Recirculation TCV Auto Auto Auto

L.P Section

[EA-685644] LCA-91-AA-001 LP Drum LCV bypass MOV Auto(Open) Auto(Close) Auto(Close)

“ LCA-91-AA-081 LP Drum LCV Auto(Close) Auto Auto(Close)

“ LBA-96-AA-001 LP Drum Pegging stop MOV Auto(Close) Auto Auto(Close)

“ LBA-96-AA-081 LP Drum Pegging PCV Auto(Close) Auto Auto(Close)

“ HAD-97-AA-001 Deaerator vent MOV Auto(Close) Auto(Open) Auto(Close)

“ HAD-98-AA-001 LP Drum I.B.D MOV Auto(Close) Auto(Close) Auto(Close)

“ LBD-90-AA-004 LP steam line drain MOV Auto(Close) Auto(Close) Auto(Close)

“ LBD-90-AA-001 LP start up vent MOV Auto(Close) Auto(Close) Auto(Close)

“ LBD-90-AA-081 LP start up vent PCV Auto(Close) Auto(Close) Auto(Close)

“ LBD-90-AA-003 LP steam small stop MOV Auto(Close) Auto(Close) Auto(Close)

“ LBD-90-AA-002 LP steam Main stop MOV Auto(Close) Auto(Open) Auto(Close)

-End-

Note ;

* The condensate stop MOV (LCA-90-AA-001) shall be opened after HRSG LP section water filling completed, if the system was earlier filled using the demineralized transfer pumps.

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1.3 HRSG Start Up

All system (GT, ST, BOP and Auxiliary system) required for proper operation of the Heat Recovery Steam Generator (HRSG) must be ready prior to initiation of unit start.

The HRSG outputs (steam evaporation rates, superheated temperatures, pressures, energy outputs at HP, IP and LP steam outlets, respectively) varies according to available exhaust heat from the gas turbines.

1.3.1 Overall HRSG Start up Operation Sequence

Most operations normally required to establish a HRSG ready to start condition after an overnight shutdown can be accomplished from the central control room. These operations are remote manual actions by the control room operator. Some activity, such as HRSG water filling and manual valve alignments for HRSG ready to start condition requires local operator actions.

1) HRSG start up preparation work for HRSG Ready to Start Condition

2) HRSG start Commend initiated by Operator

3) HRSG purge

4) GT start, load up and exhaust gas temperature matching with HRSG thermal status

5) Diverter Damper step by step opening

6) HRSG steam side drain valve operation

7) HRSG steam start up vent operation

8) Steam bypass system operation

9 HRSG steam pressure increasing within allowable range

10) HRSG steam introduction to steam header

11) GT load increase to desired load

1.3.2 HRSG Ready to Start Condition

Certain conditions must be satisfied prior to the initiations of the HRSG start. All system (Gas turbine, Steam turbine, Mechanical Auxiliary/BOP equipments and etc) required for the plant operation must be ready for operation. Followings are HRSG Ready to Start Condition.

HRSG water path filling completed.

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Set HP/IP/LP Drum level at start up water level.

1) HP Drum Start up level;

* Low start up level (If HP drum P ≤ 40 barg); -550mm from C.L.

* High start up level (If HP drum P > 40 barg); -200mm from C.L.

2) IP Drum Start up level.

* Low start up level (If IP drum P ≤ 10 barg); -450mm from C.L.

* High start up level (If IP drum P > 10 barg); -200mm from C.L.

3). LP Drum Start up level.

* Low start up level (If LP drum P ≤ 2 barg); -100mm from C.L.

* High start up level (If LP drum P > 2 barg); +300mm from C.L.

Align HP/IP/LP section valves as shown on the column labeled “Start Up” listed in the table 1,2 and 3.

One of feedwater pump is running

One of condensate pump is running

Guillotine Blanking Plate full opened

Diverter Damper close to HRSG and ready

Stack Damper full opened

One of CPH Recirculation pumps is running

1.3.3 HRSG Start up Sequence

The HRSG can be started up using either of the two following methods which can be selected by the operating personnel;

1) HRSG start up with GT start up.

In this case, GT and HRSG are started up commonly with use of the diverter damper system.

2) HRSG start up at GT operation.

In this case, the HRSG is started up by using the diverter damper while the GT is in operation. Before switch over from simple cycle to combined cycle mode, the GT has to be shutdown (if

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the HRSG is not purged) or load decreased and subsequently the GT exhaust gas temperature reduced to the required condition for the HRSG purging process and temperature matching.

Description Action

1 Start Operator initiate HRSG start command

2 Plant Purge The purging concept involves that the bypass stack and the HRSG will be purged prior every GT start (ignition) for both simple cycle and combined cycle start. Once the purge has been completed, it remains set in memory if the GT has remained in continuous operation with no trips. Provided that the purge completed remains set, GT exhaust flow can re-enter HRSG without re-purge for the HRSG start.

HRSG and bypass stack side shall be purged by GT with proper rotation/minute for purge and by change the position of the diverter damper. The purge duration is determined according to NFPA requirement. The minimum purge duration shall be min. 5 minutes or five (5) purge volume changes, whichever longer. According to the NFPA requirements, the exhaust gas temperature for purging purpose is selected at least 56 deg.C below the lowest autoignition temperature of the fuel. In this project, the purge will be done by spinning of the GT without firing, thus exhaust gas temperature for purging process will be ambient air

After HRSG has been purged, the diverter damper is moved to HRSG closed position.

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Description Action

3 GT ignition and Gas temperature

matching

As soon as bypass stack and HRSG purge completed, the GT ignition and accelerating is initiated. In case of GT in already operation in simple cycle mode, the GT load decrease and subsequently the GT exhaust gas temperature reduced to the required condition for the gas temperature matching.

The GT gas temperature set point is determined which depends on the thermal status of HRSG (e.g HP Supereheater Header Metal temperature). For cold start up of HRSG (e.g, the HP SH Header metal temperature < 370 deg.C), GT exhaust gas temperature of approximately 370 deg.C shall be considered as maximum limit. But for hot or warm start-up of HRSG, in order to avoid unnecessary cooling down of the HRSG, GT exhaust gas temperature shall be selected at HP final superheater header metal temperature (HAH-90-CT-008~015, average value) plus 50 deg.C.

4 Diverter damper operation

After GT exhaust gas temperature is achieved at temperature set point, the diverter damper can be opened as following step.

1) Diverter damper to be opened with 20% exhaust flow for a minimum of 10 minutes (Damper opening angle approximately at 35 degree, measured from HRSG full close position).

2) Diverter damper to be opened with 50% exhaust flow for a minimum of 10 minutes and until HP,RH,LP steam bypass system/Condenser vacuum available (Damper opening angle approximately at 70 degree, measured from HRSG full close position).

3) Diverter damper to be opened with 100% exhaust flow (Damper opening angle at 90 degree, measured from HRSG full close position).

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Description Action

5 HP steam stop MOV operation

* Main stop MOV (LBA-90-AA-003)

* Small stop MOV (LBA-90-AA-004)

1) Lead HRSG HP steam stop MOV ;

The Main stop MOV is opened at the initiation of the HRSG start while the bypass stop MOV is closed. And the HP main steam header is warmed, drained and pressurized along with the HRSG.

2) Lag HRSG HP steam stop MOV ;

The lag HRSG is started with closed steam stop valves. When the following conditions are satisfied, Open small bypass stop valve first.

* Temperature difference between lag HRSG steam and operation header steam is lower than 50 deg.C.

* The lag HRSG steam pressure is higher (Approximately, 2 bar) than the operation header pressure.

After small bypass stop valve open, then open the main stop valve and close the small bypass stop valve.

3) Last HRSG HP steam stop MOV ;

The last HRSG HP steam stop MOV’s operation is the same with lag HRSG.

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Description Action

6 CRH steam stop MOV operation

* CRH Steam Stop MOV (LBC-90-AA-001)

1) Lead HRSG CRH steam stop MOV ;

The CRH steam stop MOV is opened at the initiation of the HRSG start. And the CRH steam header is warmed, drained and pressurized along with the HRSG.

2) Lag HRSG CRH steam stop MOV ;

The lag HRSG reheater is started with closed steam stop valves. Thus, the reheater is initially isolated from the cold reheat steam header. Steam from the HP steam bypass system passes through the reheater to the condenser via the HRH steam bypass system.

When the hot reheat steam conditions are satisfied, the lag HRSG HRH steam isolation valve open initiated. At this moment, the CRH steam stop valve will be opened simultaneously.

3) Last HRSG CRH steam stop MOV ;

The last HRSG CRH steam stop MOV’s operation is the same with lag HRSG.

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Description Action

7 LP steam stop MOV operation

* Main stop MOV (LBD-90-AA-002) /

* Small stop MOV (LBD-90-AA-003)

1) Lead HRSG LP steam stop MOV ;

The Main stop MOV is opened at the initiation of the HRSG start while the bypass stop MOV is closed. And the LP main steam header is warmed, drained and pressurized along with the HRSG.

2) Lag HRSG LP steam stop MOV ;


* Temperature difference between lag HRSG steam and operation header steam is lower than 30 deg.C.

* The lag HRSG steam pressure is higher (Approximately, 0.5 bar) than the operation header pressure.


3) Last HRSG LP steam stop MOV ;

The last HRSG LP steam stop MOV’s operation is the same with lag HRSG.

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Description Action

8 Drain operation (HP)

Drain will be operated for removing condensate from HRSG steam path.

1. Open HP SH drain MOV (HAH-90/91-AA-001, LBA-90-AA-001), when HP Drum pressure (HAD-90-CP-001/002/003) above 1 barg.

* Close after 5 minutes time delay, if HP drum pressure reaches or higher than 15 barg.

* Intermediate position according to the system pressure when valve open required.

1 barg ≤ HP Drum Press. < 15 barg ; full open.

15 barg< HP Drum Press.; intermediate open (20% open).

* Place into auto. control mode after close.

2. Open HP steam line drain MOV (LBA-90-AA-005), when HP Drum pressure (HAD-90-CP-001/002/003) above 1 barg.

* Close after 5 minutes time delay, if HP drum pressure reaches or higher than 15 barg and HP steam stop MOV (LBA-90-AA-003) open.


1 barg ≤ HP Drum Press. < 15 barg ; full open.

15 barg< HP Drum Press.; intermediate open (20% open).


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Description Action

9 Drain operation (RH)

1. Open CRH steam line drain MOV (LBC-90-AA-002), when RH steam pressure (LBB-90-CP-001/002/003) above 1 barg.

* Close after 5 minutes time delay, if RH steam pressure reaches or higher than 5 barg and CRH steam stop MOV (LBC-90-AA-001) open.


1 barg ≤ RH Press. < 15 barg ; full open.

15 barg< RH Press; intermediate open (20% open).

* Place into auto. Control mode after close.

2. Open RH and HRH steam line drain MOV (HAJ-90-AA-001, LBB-90-AA-002), when RH steam pressure (LBB-90-CP-001/002/003) above 1 barg.

* Close after 5 minutes time delay, if RH steam pressure reaches or higher than 5 barg.


1 barg ≤ RH Press. < 15 barg ; full open.

15 barg< RH Press; intermediate open (20% open).

* Place into auto. Control mode after close.

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Description Action

10 Drain operation (IP)

1. Open IP steam line drain MOV (LBA-95-AA-003) when IP Drum pressure (HAD-94-CP-001/002/003) above 1 barg.

* Close after 5 minutes time delay, if IP Drum pressure reaches or higher than 5 barg and IP Steam PCV (LBA-95-AA-081) open more than 10 %.


1 barg ≤ IP Drum Press. < 15 barg ; full open.

15 barg< IP Drum Press; intermediate open (20% open).


11 Drain operation (LP)

1. Open LP steam line drain MOV (LBD-90-AA-004) when LP Drum pressure (HAD-97-CP-001/002/003) above 0.5 barg.

* Close after 5 minutes time delay, if LP Drum pressure reaches or higher than 2 barg.


12 Start Up Vent Operation (HP)

Vent will be operated for extracting any non-condensable gas from HRSG steam path.

1. Open HP start up vent MOV (LBA-90-AA-002) when HP Drum pressure (HAD-90-CP-001/002/003) above 0.5 barg.

* Close when HP Drum pressure reaches 2 barg.

13 Start Up Vent Operation (RH)

The RH start up vent will control the RH pressure increasing rate, if RH steam bypass system (Condenser vacuum) is not ready condition.

1. Open RH start up vent isolation MOV (LBB-90-AA-001) when RH steam pressure (LBB-90-CP-001/002/003) above 0.5 barg.

2. The RH start up vent PCV (LBB-90-AA-081) will control the RH pressure change rate within allowable range (1 bar/min).

3. Close RH start up vent MOV and PCV when the RH steam bypass system (Condenser vacuum) is available.

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Description Action

14 Start Up Vent Operation (IP)

Vent will be operated for extracting any non-condensable gas from HRSG steam path.

1. Open IP start up vent MOV (LBA-95-AA-001) when IP Drum pressure (HAD-94-CP-001/002/003) above 0.5 barg.

* Close when IP Drum pressure reaches 1.5 barg.

15 Start Up Vent Operation (LP)

The LP start up vent will control the LP Drum pressure increasing rate, if LP steam bypass system (Condenser vacuum) is not ready condition.

1. Open LP start up vent isolation MOV (LBD-90-AA-001) when LP Drum pressure (HAD-97-CP-001/002/003) above 0.5 barg.

2. The LP start up vent PCV (LBD-90-AA-081) will control the LP Drum pressure change rate within allowable range (0.3 bar/min).

3. Close LP start up vent MOV and PCV when the LP steam bypass system (Condenser vacuum) is available.

16 Steam Bypass System Operation

Each Steam Bypass System will be operated to control the HRSG Pressure.

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Description Action

17 GT and HRSG load up

In line with the admitting of the GT exhaust gas, the metal of the heat transfer surface is heated up and steam is formed in the evaporators, which leads to a partly water ejection from the evaporators into the drums.

After HP-steam temperature approaches the GT exhaust gas temperature and as soon as the HP drum level has stabilized at operating level and a sufficient amount of HP steam (Min. 25%of MCR flow and 40barg of HP Drum pressure) is produced, the GT output and hence also the exhaust gas temperature can be increased with the pressure gradients allowed for the thick-walled and/or high temperature loaded components such as HP-drum.

The allowable HP-drum pressure change rate are as follows;

* 0% to 30% Pressure range; 2 bar/minute.



In addition, if the wall temperature difference exceeds limiting value in the following component, the GT load up would stop to reduce thermal stress.

* Allowable Wall differential temperature (HAD-90-CT-001 vs HAD-90-CT-002) at HP drum lower side ; 50 deg.C

* Allowable Wall differential temperature (HAD-90-CT-003 vs HAD-90-CT-004) at HP drum upper side ; 50 deg.C

* Allowable Wall differential temperature (HAH-90-CT-008 vs HAH-90-CT-009, or HAH-90-CT-010 vs HAH-90-CT-011, or HAH-90-CT-012 vs HAH-90-CT-013, or HAH-90-CT-014 vs HAH-90-CT-015 ) at HP S.H outlet header ; 40 deg.C

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Description Action

18 Continuous blowdown valve

operation (HP/IP)

Continuous blowdown will be operated.

1. Open the HP continuous blowdown isolation MOV (HAD-91-AA-002) when HP steam flow (LBA-90-CF-001/002) is higher than 20 % MCR flow.

2. Open the IP continuous blowdown isolation MOV (HAD-95-AA-002) when IP steam flow (LBA-95-CF-001/002) is higher than 20 % MCR flow.

19 LCV set point change

Drum level set point should be changed from start up water level into Normal water level when load greater than 25% MCR flow.

* HP drum N.W.L; 0 mm from Drum Center line.

* IP drum N.W.L; 0 mm from Drum Center line.

* LP drum N.W.L; +500 mm from Drum Center line.

1.3.4 HRSG Start up from Warm or Hot condition

For starting the HRSG from a warm or hot condition, steps are the same with above sequence.

1.3.5 Succeeding HRSG Start up

The lag or last HRSG is started in a similar manner to the lead HRSG.

After first GT, HRSG and ST are on-line s lead, succeeding GT and HRSG can be started as lag by operator’s initiation of remaining GT and HRSG start up. When succeeding GT and HRSG is initiated for start up, HRSG should already be prepared for start up conditions as summarized in clause 2.3.2 HRSG Ready to Start Condition above. With the start of HRSG, steam flow will be established through HRSG steam line. AS ST and Condenser are on-line, produced steam can be dumped to the condenser through the steam bypass system until each steam can be equalized to steam lines of leading HRSG.

1.4 HRSG Load Operation

The HRSG outputs (steam evaporation rates, superheated temperatures, pressures, energy outputs) vary according to available exhaust heat from the gas turbines. The HRSG is operated following GT load according to the plant demand.

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Steam production increase from the part load to base load is performed by increasing the load of the GT. HRSG runback is achieved by GT load decrease.

The HRSG operating pressure is operated in natural sliding pressure mode between 100% and 40% of rated pressure depending on the steam mass flow into the steam turbine. In part load operation, the HRSGs are oeperated in fixed pressure mode, means the pressure is controlled by the steam turbine throttle oeperation. For the detail of the plant operation characteristic, please refer to the Heat and Mass Balance Calculation [Doc.no. EE-00001].

The HRSG load is dierectly depending on the GT operation. Generally, 30% of MCR steam flow load operation as minimum is recommended at which the drum level is relatively stable.

1.5 HRSG Shut down

Normal shut down is organized to leave the steam cycle pressurized and hot. This is done to obtain the fastest restart possible and to minimize life expenditure for the plant. The HRSG shut down is performed by the diverter damper close to HRSG as following actions.

1.5.1 HRSG Shut Down Concept

The HRSG shut down is performed by the diverter damper close with normal speed (60 seconds)

1) Diverter damper close to HRSG

2) As the remaining heat in the HRSG, Steam bypass system control the HRSG pressure

3) Close the steam stop valve

4) Close all continuous blowdown valves

5) If there is no demand of feedwater supply, close all feed water stop valves.

6) Stop the C.P.H recirculation pumps

7) Close stack damper

1.5.2 HRSG Shut down Sequence

The HRSG will be shutdown as following sequence ;

Description Action

1 Shut down Operator initiate HRSG shutdown command

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Description Action

2 Diverter damper close

The Diverter damper will be closed with normal speed (60 seconds). Now, HRSG can be isolated from the GT.

3 Steam Bypass System Operation

HP/RH/LP steam bypass system will be operated, thereby diverting steam from the HRSG through the associated steam bypass system.

4 HP Steam Stop MOV Close

The HP steam stop MOV (LAB-90-AA-003) will be closed.

1) Lead HRSG HP steam stop MOV ;

The HP steam stop valve will be closed when HRSG shutdown initiated and HP steam bypass system open sufficiently (about 10%). The HP steam bypass set point of the HRSG is slowly ramped below (about 2 bar) the operating pressure, thereby diverting steam from the HP steam through the HP steam bypass system.

2) Lag HRSG HP steam stop MOV ;

The lag HRSG HP steam stop MOV’s operation is the same with lead HRSG.

3) Last HRSG HP steam stop MOV ;

During the last unit shutdown, the Steam turbine MCV is ramped closed. The Steam turbine continues to unload and finally the Steam turbine valves are tripped closed. When the ST is tripped, the last HRSG HP and HRH steam stop valves are closed.

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Description Action

5 CRH Steam Stop MOV Close

The CRH steam stop MOV (LBC-90-AA-001) will be closed.

1) Lead HRSG CRH steam stop MOV ;


The lead HRSG HP steam is isolated from the HP header.

At this moment, the HRH, CRH and LP steam stop valve will be closed simultaneously.

2) Lag HRSG CRH steam stop MOV ;

The lag HRSG CRH steam stop MOV’s operation is the same with lead HRSG.

3) Last HRSG CRH steam stop MOV ;

During the last unit shutdown, the Steam turbine MCV is ramped closed. The Steam turbine continues to unload and finally the Steam turbine valves are tripped closed. When the ST is tripped and HP steam bypass system is completely closed, the last HRSG CRH steam stop valve is closed.

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Description Action

6 LP Steam Stop MOV Close

The LP steam stop MOV (LBD-90-AA-002) will be closed.

1) Lead HRSG LP steam stop MOV ;


The lead HRSG HP steam is isolated from the HP header.


2) Lag HRSG LP steam stop MOV ;

The lag HRSG LP steam stop MOV’s operation is the same with lead HRSG.

3) Last HRSG LP steam stop MOV ;

During the last unit shutdown, the ST LP control valve is placed in position control and ramped closed. At this moment, the HRSG LP steam stop is closed.

7 IP Steam Stop MOV Close

The IP steam stop MOV (LBA-95-AA-002) will be closed after IP steam PCV (LBA-95-AA-081) fully closed.

8 Continuous blowdown MOV close (HP/IP)

Continuous blowdown MOV will be closed.

1. Close the HP continuous blowdown isolation MOV (HAD-91-AA-002) when HP steam flow (LBA-90-CF-001/002) is lower than 20 % MCR flow.

2. Close the IP continuous blowdown isolation MOV (HAD-95-AA-002) when IP steam flow (LBA-95-CF-001/002) is lower than 20 % MCR flow.

9 HP feedwater stop MOV Close

The HP feedwater stop MOV (LAB-90-AA-001) can be closed when no demand of feedwater supply. This MOV will be closed after HP drum LCV(HAC-90-AA-081 and 082) fully closed.

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Description Action

10 IP feedwater stop MOV Close

The IP feedwater stop MOV (LAB-94-AA-001) can be closed when no demand of feedwater supply. This MOV will be closed after IP drum LCV(HAC-94-AA-081) fully closed.

11 Condensate stop MOV Close

The condensate stop MOV (LCA-90-AA-001) can be closed when no demand of condensate supply. This MOV will be closed after LP drum LCV (LCA-91-AA-081) fully closed.

12 C.P.H Recirculation pumps stop

Stop the C.P.H recirculation pumps

13 Stack Damper Close

Close stack damper

1.6 Special operations

1.6.1 HRSG Trip

The HRSG protection item, which cause HRSG trip is summarized in Clause.4. In case of HRSG protection signal detected, the HRSG is tripped by quick closing of diverter damper within 20 seconds.

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1.6.2 Gas Turbine Trip

In case of a GT trip, the HRSG has also to be tripped to avoid cooling of HRSG by running down GT. The HRSG is tripped by quick closing of diverter damper within 20 seconds.

1.6.3 Steam Turbine Trip

Steam Turbine Trip does not make any impact on the HRSG itself. The HRSG can be operated by dumping steam generated from the HRSG to the condenser through the steam bypass system or HRSG can be shutdown decided by operator.

1.6.4 HRSG (Gas Turbine) Run Back

The HRSG Run Back will be achieved by the Gas Turbine Run Back (load reducing) as following events.

If HRSG inlet duct Gas temperature (HNA-90-CT-001/002/003) ≥ 655 deg.C (Alarm H), the GT Run Back until alarm disappeared.

If HP final steam temperature (LBA-90-CT-001/002/003) ≥ 575 deg.C (Alarm H), the GT Run Back until alarm disappeared.

If RH final steam temperature (LBB-90-CT-001/002/003) ≥ 574 deg.C (Alarm H), the GT Run Back until alarm disappeared.

2 HRSG CONTROL DESCRIPTION HRSG equipment is controlled from the DCS placed in the central control room. The following control schemes are envisaged in the Heat Recovery Steam Generator (HRSG) control system.

2.1 Drum level control

The drum level control maintains a drum level set point by controlling the flow of feedwater through a valve arrangement. Provision is also made to compensate for shrink and swell of water in the drum and for a feed forward element derived from balancing water into the drum and steam out of the drum.

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2.1.1 HP Drum Level Control

Control Schematic Diagram;

The drum level/feed water control comprises of a single element drum level control operating on low load operation and a three element control operating on full load operation. The single element control is envisaged for controlling the drum level during low load up to 25% MCR. The three element control is envisaged for drum level control from 25% MCR to 100% MCR.

Valve composition ;

* Full load station ; Motorized isolation valve(HAC-90-AA-001), Control valve(HAC-90-AA-081)

* Low load station ; Motorized isolation valve(HAC-90-AA-002), Control valve(HAC-90-AA-082)

Single element control;

The median value of the drum level (HAD-90-CL-001/002/003) is compensated for the drum pressure (HAD-90-CP-001/002/003). The compensated output is selected for load less than 25% MCR. The measured level is compared with the set value and the error is applied to the controller for positioning the level control valve. The drum level shall have two start up level set

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points namely high start up level set point and low start up level set point. The set point should be changed according to the drum pressure increasing.

HP drum start up level set point;

* Low start up level set point; -550mm from C.L. (If HP drum pressure is lower than 40 barg)

* High start up level set point; -200mm from C.L. (If HP drum pressure is higher than 40 barg)

These set points will switch over to normal set point from start up set point when load above 25% MCR.

* HP drum normal set point; 0mm from C.L

Three element control;

This control is used for load greater than 25% MCR. It is based on three parameters namely drum level, steam flow and feed water flow.

The steam flow (LBA-90-CF-001/002) is applied as a feed forward signal to the drum level controller and the output of the controller is given as the set point for the feed water flow controller. The feedwater flow (LAB-90-CF-001/002) is added to the controller as a feedback signal.

The valves controlling the water feed to the drum are in a two valve arrangement consisting of a 30% valve for low load and a 100% valve for full load control.

The low load and full load control valves are arranged in a parallel split-range manner to provide good flow control through a wide range of control valve pressure drop. The low load valve handles the smaller flows until it is nearly fully open then full load valve opens to handle the large flows. The opposite action occurs on decreasing flow. Generally, the flow capacity ratio of the two valves is chosen to ensure that the drum level control remains as single-element during start-up and the transfer of control valves occurs after three-element drum level control has commenced.

For increasing flow, the full load control valve opens when the low load control valve is almost fully open (approximately 90% stoke). After the transfer, the low load valve is fully closed ensuring that the full load valve will not operate near to its seat. For decreasing flow, the low load valve is opened and the larger valve is fully closed at the transfer point.

A motorized isolation valve on the inlet of each control valve is supplied to isolate the control valve during shutdown/maintenance period and automatically opened when HRSG start initiated.

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2.1.2 IP Drum Level Control


The drum level/feed water control comprises of a single element drum level control operating on low load operation and a three element control operating on full load operation. The single element control is envisaged for controlling the drum level during low load up to 25% MCR. The three element control is envisaged for drum level control from 25% MCR to 100% MCR.

Valve composition;

* Inching type Motorized bypass valve (HAC-94-AA-001), Control valve (HAC-94-AA-081)


The median value of the drum level (HAD-94-CL-001/002/003) is compensated for the drum pressure (HAD-94-CP-001/002/003). The compensated output is selected for load less than 25% MCR. The measured level is compared with the set value and the error is applied to the controller for positioning the level control valve. The drum level shall have two start up level set points namely high start up level set point and low start up level set point. The set point should be changed according to the drum pressure increasing.

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IP drum start up level set point;

* Low start up level set point; -450mm from C.L. (If IP drum pressure is lower than 10 barg)

* High start up level set point; -200mm from C.L. (If IP drum pressure is higher than 10 barg)

These set points will switch over to normal set point from start up set point when load above 25% MCR.

* IP drum normal set point; 0mm from C.L`


This control is used for load greater than 25% MCR. It is based on three parameters namely drum level, steam flow and feed water flow.

The steam flow (LBA-95-CF-001/002) is applied as a feed forward signal to the drum level controller and the output of the controller is given as the set point for the feed water flow controller. The feedwater flow (LAB-94-CF-001/002) is added to the controller as a feedback signal.

In the event of failure of the control valve, the inching type motorized bypass valve can be used by the manual signal from the control room.

2.1.3 LP Drum Level Control


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The drum level/condensate water control comprises of a single element drum level control operating on low load operation and a three element control operating on full load operation. The single element control is envisaged for controlling the drum level during low load up to 25% MCR. The three element control is envisaged for drum level control from 25% MCR to 100% MCR.

Valve composition ;

* Inching type Motorized bypass valve (LCA-91-AA-001), Control valve (LCA-91-AA-081)


The median value of the drum level (HAD-97-CL-001/002/003) is compensated for the drum pressure (HAD-97-CP-001/002/003). The compensated output is selected for load less than 25% MCR (condensate flow). The measured level is compared with the set value and the error is applied to the controller for positioning the level control valve. The drum level shall have two start up level set points namely high start up level set point and low start up level set point. The set point should be changed according to the drum pressure increasing.

LP drum start up level set point;

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* Low start up level set point; -100mm from C.L. (If LP drum pressure is lower than 2 barg)

* High start up level set point; +300mm from C.L. (If LP drum pressure is higher than 2 barg)

These set points will switch over to normal set point from start up set point when load above 25% MCR (condensate flow).

* LP drum normal set point; +500mm from C.L


This control is used for load greater than 25% MCR (condensate flow). It is based on three parameters namely drum level, summed drum out flow and condensate flow.

The summed drum out flow [LP steam flow(LBD-90-CF-001/002) + HP feedwater flow(LAB-90-CF-001/002) + IP feedwater flow(LAB-94-CF-001/0020)] is applied as a feed forward signal to the drum level controller and the output of the controller is given as the set point for the condensate flow controller. The condensate flow (LCA-90-CF-001/002) is added to the controller as a feedback signal.

In the event of failure of the control valve, the inching type motorized bypass valve can be used by the manual signal from the control room.

2.2 HP Final Steam Temperature Control


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The HP superheater steam desuperheater function is to control HRSG superheater outlet steam temperature within allowable condition. The set point is 567 deg.C.

Valve composition ;

* Motorized block valve (LAE-90-AA-001), Control valve (LAE-90-AA-081)

* Inching type motorized bypass valve (LAE-90-AA-002)

To ensure that all water droplets are evaporated and to minimize potential temperature shocks resulting from the introduction of spray water, the desuperheater is placed at the inlet to the HP final superheater. The amount of spray water must be limited to avoid driving the HP final superheater inlet steam into the saturation region.

HP superheater steam desuperheater control utilizes two controllers in a cascade arrangement namely "outer" controller and “inner” controller. The setpoint of outer controller is the desired HRSG HP superheater outlet steam temperature and the feedback is the HRSG HP superheater outlet steam temperature (LBA-90-CT-001/002/003) measured at the outlet of the final superheater. The set point is 567 deg.C at the final superheater outlet.

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The output of the outer controller is the temperature setpoint of the inner controller. This controller positions the HP desuperheater spray water control valve. The feedback of the inner controller is the steam temperature (HAH-90-CT-002/003/004) at the inlet to the final superheater. In effect, the outer controller controls the final HRSG HP superheater outlet steam temperature by adjusting the temperature of the steam entering the final stage of superheating.

Since there is a possibility of overspraying and forcing steam to saturation temperature at the inlet of the HP final superheater, the setpoint of the inner controller has a minimum limit of the present saturation temperature plus a margin (+28 deg.C). The saturation temperature is determined from the saturation temperature from HP drum pressure measurements (HAD-90-CP-001/002/003).

This steam temperature control is permissive only when the HP steam flow (LBA-90-CF-001/002) is higher than 20% of MCR flow to avoid any steam condensation in steam path.

A motorized block valve is placed in the spray water line in series with a spray control valve. The block valve is automatically closed whenever the desuperheater control is not enabled and automatically opened when enabled.

In the event of failure of the control valve, the inching type bypass valve can be used by the manual signal from the control room.

2.3 Reheater Final Steam Temperature Control


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The Reheater steam desuperheater function is to control HRSG reheater outlet steam temperature within allowable condition. The set point is 566 deg.C.

Valve composition;

* Motorized block valve (LAF-90-AA-001), Control valve (LAF-90-AA-081)

* Inching type motorized bypass valve (LAF-90-AA-002)

To ensure that all water droplets are evaporated and to minimize potential temperature shocks resulting from the introduction of spray water, the desuperheater is placed at the inlet to the final reheater. The amount of spray water must be limited to avoid driving the final reheater inlet steam into the saturation region.

Reheater steam desuperheater control utilizes two controllers in a cascade arrangement namely "outer" controller and “inner” controller. The setpoint of outer controller is the desired HRSG reheater outlet steam temperature and the feedback is the HRSG reheater outlet steam temperature (LBB-90-CT-001/002/003) measured at the outlet of the final reheater. The set point is 566 deg.C at the final reheater outlet.

The output of the outer controller is the temperature setpoint of the inner controller. This controller positions the reheater desuperheater spray water control valve. The feedback of the

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inner controller is the steam temperature (HAJ-90-CT-002/003/004) at the inlet to the final reheater. In effect, the outer controller controls the final HRSG reheater outlet steam temperature by adjusting the temperature of the steam entering the final stage of reheater.

Since there is a possibility of overspraying and forcing steam to saturation temperature at the inlet of the final reheater, the setpoint of the inner controller has a minimum limit of the present saturation temperature plus a margin (+28 deg.C). The saturation temperature is determined from the saturation temperature from hot reheat steam pressure measurements (LBB-90-CP-001/002/003).

This steam temperature control is permissive only when the HP steam flow (LBA-90-CF-001/002) is higher than 20% of MCR flow to avoid any steam condensation in steam path.

A motorized block valve is placed in the spray water line in series with an spray control valve. The block valve is automatically closed whenever the desuperheater control is not enabled and automatically opened when enabled.

In the event of failure of the control valve, the inching type bypass valve can be used by the manual signal from the control room.

2.4 IP Steam Pressure Control and IP steam stop MOV


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The HRSG is equipped with IP steam pressure control valve and steam stop MOV in series to Cold Reheater line. Large, rapid variations in IP drum pressure can cause rapid variations in the drum level. Pressure change causes the void fractions in the evaporator and drum to enlarge (on rapid pressure decay) or shrink (on rapid pressure rise), causing the water in the drum to rise above or fall below NWL. Maintaining stable IP drum pressure greatly helps maintaining a stable IP drum level.

Valve composition ;

* Control valve (LBA-95-AA-081), IP steam stop MOV (LBA-95-AA-002)

HRSG start-up shall be initiated with closed control valve. Then valve operation will be initiated as followings.

Open control valve to 10 % when the IP steam pressure (LBA-95-CP-001/002) above 3 barg and hold this position until the IP steam pressure reaches 10 barg. Then the control valve shall modulate to maintain this pressure (10 barg).

With this control, the control valve will open continuously to full open position when the cold reheat steam line is pressurized above 10 barg.

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Another function is that, during plant transient operation, if the IP steam pressure drops too fast, the pressure decay rate will be controlled by acting to close this control valve. The control valve shall control the IP steam pressure (LBA-95-CP-001/002) decay rate within -0.1bar/s.

The IP steam stop MOV will be opened from the initial start up and always open during operation. During shutdown period, this valve can be closed when IP steam PCV is completely closed.

2.5 LP Drum Pressure Control


The LP drum pressure is pegged by admitting supplementary steam from a higher pressure/enthalpy source, the IP steam line. The pegging steam system includes piping from the IP steam line to the LP drum, a motorized isolation valve and control valve.

Valve composition ;

* Motorized isolation valve(LBA-96-AA-001), Control valve(LBA-96-AA081)

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The pegging steam supply has the following functions. And this control is active only if the IP drum pressure is higher than 10 barg.

* Mainly Oil firing operation case, It is expected that insufficient flue gas energy available at the LP evaporator to maintain the LP drum pressure high enough to prevent gas side corrosion. Pegging steam from the IP steam line maintains a minimum LP drum pressure and a resultant LP drum water temperature. The set point (3 barg) is compared with the LP drum pressure (HAD-97-CP-001/002/003). The difference is the input signal for the controller of the control valve.

* When the feedwater pump suction is taken from the LP drum, pegging steam prevents a rapid decay of LP drum pressure to limit the generation of steam voids in the drum and BFP suction line water. If LP drum pressure drops too fast, the pressure decay rate will be controlled by providing pegging steam. The pegging steam control valve shall control the LP drum pressure (HAD-97-CP-001/002/003) decay rate within -0.007 bar/s.

The motorized isolation valve at the inlet of control valve is supplied to prevent any possible leakage of the control valve. Also this valve will provide a tight isolation from the IP steam system when no demand of steam supply. The motorized isolation valve is automatically closed whenever the control is not enabled and automatically opened when enabled.

The motorized isolation valve will be protectionally closed when the LP drum pressure (HAD-97-CP-001/002/003) is higher than 7 barg.

2.6 Condensate Preheater Recirculation Control


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The condensate preheater (CPH) is located outlet of HRSG and heated by exhaust gas before leaving the main stack. The CPH inlet temperature control is to raise the temperature of the condensate entering the CPH to avoid flue gas corrosion in the CPH tube. A temperature control valve modulates the discharge flow of the CPH recirculation pumps to recirculate hot water from the outlet of the CPH to the inlet of the CPH where it mixes with cold condensate flow.

The design Gas fuel composition used for the plant operation indicates zero sulfur concentration. The fixed set point of 70 deg.C is enough to prevent corrosion for Gas fuel operation. When the higher sulfur content fuel used, such as Oil operation, the CPH will be completely bypassed.

Composition ;

* 2X100% Recirculation pumps (LCA-92/93-AP-002)

* Temperature control valve(LCA-94-AA-081)

One of recirculation pump should be placed into service before starting the HRSG.

The fixed set point, 70deg.C is compared with the CPH inlet temperature (LCA-90-CT-003/004) signal. The difference is the input signal for the controller of the control valve.

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In addition to the above temperature control, following control for recirculation pumps protection is also incorporated.

To prevent less flow operation of pumps, the recirculation system controls must limit the closure of control valve when the recirculation pump flow reaches low flow set point (65,000 kg/hr). The low flow set point would be slightly above the actual minimum flow of recirculation pumps. The recirculation pump flow is measured using flow transmitter (LCA-94-CF-001/002) located at the discharge of pump. The operation pump must be tripped and the stand by pump starts if the measured pump flow falls to the minimum flow trip setting (60,000 kg/hr).

To prevent excessive flow from the pumps, the recirculation high flow set point (300,000 kg/hr) would be set below the recirculation pump maximum allowable continuous flow in order to limit the further opening of control valve when the recirculation pump flow approaches the high flow. The operation pump must be tripped and the stand by pump starts if the pump flow equals or exceeds the maximum allowable continuous flow setting (330,000 kg/hr).

2.7 Condensate Preheater 3-way valve Control


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The condensate preheater system is equipped with a condensate bypass system. The three-way valve sends condensate water flow to the condensate preheater and/or bypass around the condensate preheater.

The three-way valve can be positioned to ;

* direct all condensate flow to the condensate preheater,

* direct all condensate flow through the condensate preheater bypass,

* direct any portion of the flow to either the preheater or the bypass around the condensate preheater.

Valve composition ;

* 3-way valve (LCA-90-AA-081)

For Gas firing Operation;

The 3-way valve is positioned to full open to the bypass direction before HRSG start. During start up period, no cold condensate would be introduced into CPH tube while all condensate is

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bypassed by 3-way valve in order to prevent possible flue gas corrosion in the CPH tube. The 3-way valve can be positioned to full open to the CPH direction after steam bypass operation is finished and all steam introduced into the steam turbine.

After then the subcool temperature control will be initiated as following.

The three-way valve is positioned to route a portion of the condensate flow to the condensate preheater bypass as required to hold a minimum subcooling before entering the deaerator to ensure an optimum deaeration process.

The function of this control is to maintain condensate temperature several degrees below saturation temperature to achieve a good deaeration performance in the deaerator. It is accomplished by 3-way valve valve to split the incoming condensate flow between the CPH and a bypass around the CPH.

If the temperature difference between the saturation temperature calculated from the LP drum pressure (HAD-97-CP-001/002/003) and the CPH outlet temperature (LCA-91-CT-001/002) is lower than 8 deg.C, the 3-way valve will be opened partially into the bypass direction in order to make a cold condensate bypass flow and therefore reduce the temperature of CPH outlet condensate before entering the deaerator.

The CPH full bypass operation shall be required in some case. When the CPH recirculation pumps are all failure longer than 10 minutes, the three-way valve is positioned in the fully-closed position to the CPH, resulting in all the condensate flow bypassing the condensate preheater so that the HRSG can be continuously operation without shut down.

For Oil firing Operation;

The 3-way valve is positioned to full open to bypass direction always.

2.8 Economizer and Condensate Preheater Pressure Control

The economizer/preheater pressure control is to prevent the buildup of high pressure due to economizer/preheater water expansion within a bottle-up hot economizer/preheater when the drum level control valve is closed and HRSG in service. The economizer/preheater pressure control will prevent unnecessary lifting of the economizer/preheater safety valve.

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1) HP Economizer pressure control

If HP economizer pressure (LAB-90-CP-001) reaches 188 barg, Auto open the low load LCV (HAC-90-AA-082) to 20%. The auto open function has to be effective in HRSG operation below 25% MCR and shut down period also.

The auto open command is removed if HP economizer pressure (LAB-90-CP-001) falls below 180 barg.

2) IP Economizer pressure control

If IP economizer pressure (LAB-94-CP-001) reaches 65 barg, Auto open the LCV (HAC-94-AA-081) to 20%. The auto open function has to be effective in HRSG operation below 25% MCR and shut down period also.

The auto open command is removed if IP economizer pressure (LAB-94-CP-001) falls below 55 barg.

3) Condensate Preheater(CPH) pressure control

If CPH pressure (LCA-90-CP-002) reaches 32 barg, Auto open the LCV (LCA-91-AA-081) to 20%. The auto open function has to be effective in HRSG operation below 25% MCR and shut down period also.

The auto open command is removed if CPH pressure (LCA-90-CP-002) falls below 28 barg.

2.9 Steam Drain Control

The purpose of the drain valve is to remove any accumulated condensate from the superheater/reheater and steam line and provide a flow path for steam to heat the piping during start up.

HRSG start-up shall be initiated with closed drain valves. Then drain valves operation shall be initiated as followings.

1) HP Superheater drain MOV (HAH-90-AA-001, HAH-91-AA-001, LBA-90-AA-001)

Open drain valve when HP Drum pressure (HAD-90-CP-001/002/003) above 1 barg.

Close after 5 minutes time delay, if HP drum pressure reaches or higher than 15 barg.

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Then, place MOV (HAH-90-AA-001 and LBA-90-AA-001) into auto operation mode comparing the drain pot temperature element and the saturation temperature at corresponding drum pressure measurements.

- Open when superheated 30 deg.C below.

- Close when superheated 50 deg.C above.

Place MOV (HAH-91-AA-001) into auto operation mode monitoring the drain pot level switches.

- Open when High or High/High level switch detect any condensate.

- Close when High level switch detect no condensate.

These valves shall have opening limit to prevent excess drain flow. When open demand is initiated, the valve open position shall be determined as following.

- HP Drum Pressure < 15 barg; full open.

- HP Drum Pressure > 15 barg; Intermediate (20%) open.

2) HP Steam line drain MOV (LBA-90-AA-005).

Open drain valve when HP Drum pressure (HAD-90-CP-001/002/003) above 1 barg.

Close after 5 minutes time delay, if HP drum pressure reaches or higher than 15 barg and HP steam stop MOV (LBA-90-AA-003) open.

Then, place into auto operation mode comparing the drain pot temperature element and the saturation temperature at corresponding drum pressure measurements.



This valve shall have opening limit to prevent excess drain flow. When open demand is initiated, the valve open position shall be determined as following.

- HP Drum Pressure < 15 barg; full open.

- HP Drum Pressure > 15 barg; Intermediate (20%) open.

3) CRH steam line drain MOV (LBC-90-AA-002)

Open CRH steam line drain MOV (LBC-90-AA-902), when RH steam pressure (LBB-90-CP-001/002/003) above 1 barg.

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Close after 5 minutes time delay, if RH steam pressure reaches or higher than 5 barg and CRH steam stop MOV (LBC-90-AA-001) open.

Then, place into auto operation mode monitoring the drain pot level switches.




- RH Pressure < 15 barg; full open.

- RH Pressure > 15 barg; Intermediate (20%) open.

4) Reheater and HRH steam line drain MOV (HAJ-90-AA-001, LBB-90-AA-002)

Open drain valve when RH steam pressure (LBB-90-CP-001/002/003) above 1 barg.

Close after 5 minutes time delay, if RH steam pressure reaches or higher than 5 barg.

Then, place into auto operation mode monitoring the drain pot temperature element and comparing the saturation temperature at RH steam pressure measurements.




- RH Pressure < 15 barg; full open.

- RH Pressure > 15 barg; Intermediate (20%) open.

5) IP Steam line drain MOV (LBA-95-AA-003)

Open drain valve when IP Drum pressure (HAD-94-CP-001/002/003) above 1 barg.

Close after 5 minutes time delay, if IP Drum pressure reaches or higher than 5 barg and IP Steam PCV (LBA-95-AA-081) open more than 10 %.




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- IP Drum Pressure < 15 barg; full open.

- IP Drum Pressure > 15 barg; Intermediate (20%) open.

6) LP Steam line drain MOV (LBD-90-AA-004)

Open drain valve when LP Drum pressure (HAD-97-CP-001/002/003) above 0.5 barg.

Close after 5 minutes time delay, if LP Drum pressure reaches or higher than 2 barg.




2.10 Steam Start up Vent Control

The function of these valves is to remove non condensable gas like an air from the HRSG steam side. HRSG start-up shall be initiated with closed these vent valves. Then vent valves operation shall be initiated as followings.

1) HP start up vent MOV (LBA-90-AA-002)

Open vent valves when HP Drum pressure (HAD-90-CP-001/002/003) above 0.5 barg.

Close when HP Drum pressure reaches 2 barg.

2) RH start up vent MOV (LBB-90-AA-001) and PCV (LBB-90-AA-081)

* Pressure increasing mode during start up ;

The RH start up vent will control the RH pressure increasing rate, if RH steam bypass system (Condenser vacuum) is not ready condition.

Open RH start up vent isolation MOV (LBB-90-AA-001) when RH steam pressure (LBB-90-CP-001/002/003) above 0.5 barg.

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The RH start up vent PCV (LBB-90-AA-081) will control the RH pressure change rate within allowable range (1 bar/min).

Close RH start up vent MOV and PCV when the RH steam bypass system (Condenser vacuum) is available. Then vent valve will be placed into the pressure control mode.

* Pressure control mode during normal operation;

If the RH steam pressure(LBB-90-CP-001/002/003) is reached to the set point (39.5 barg), the HP start up vent PCV (LBB-90-AA-081) open initiated and control the steam pressure, not to over than the set point. The set point is slightly lower than safety valve setting pressure. The isolation MOV will open first when the RH steam pressure is reached to 39 barg.

3) IP start up vent MOV (LBA-95-AA-001)

Open vent valves when IP Drum pressure (HAD-94-CP-001/002/003) above 0.5 barg.

Close when IP Drum pressure reaches 1.5 barg.

4) LP start up vent MOV (LBD-90-AA-001) and PCV (LBD-90-AA-081)

* Pressure increasing mode during start up ;

The LP start up vent will control the LP Drum pressure increasing rate, if LP steam bypass system (Condenser vacuum) is not ready condition.

Open LP start up vent isolation MOV (LBD-90-AA-001) when LP Drum pressure (HAD-97-CP-001/002/003) above 0.5 barg.

The LP start up vent PCV (LBD-90-AA-081) will control the LP Drum pressure change rate within allowable range (0.3 bar/min).

Close LP start up vent MOV and PCV when the LP steam bypass system (Condenser vacuum) is available. Then vent valve will be placed into the pressure control mode.

Pressure control mode during normal operation;

If the LP steam pressure (LBD-90-CP-001/002/003) is reached to the set point (8 barg), the LP start up vent PCV (LBD-90-AA-081) open initiated and control the steam pressure, not to over than the set point. The set point is slightly lower than safety valve setting pressure. The isolation MOV (LBD-90-AA-001) will open first when the LP steam pressure is reached to 7.5 barg.

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5) Deaerator vent MOV (HAD-97-AA-001)

This vent MOV will be opened when HRSG start initiated and always opened during HRSG operation. This valve can be closed after HRSG shutdown completed (Stack Damper close).

2.11 Drum Continuous Blowdown Control

Continuous blowdown basically controls the T.D.S and silica level of the drum water. Blowdown flow of drum water is continuous and controlled manually by the operator in the control room based on the feed back of drum and steam quality. An isolation MOV for tight shut off and an manual blowdown valve for fine control in series are provided for this control.

1) HP Continuous Blowdwon MOV (HAD-91-AA-002)

The HRSG start up will be initiated with closed blowdown MOV.

The blowdown MOV shall be opened after HP steam flow (LBA-90-CF-001/002) is higher than 20 % MCR flow and also shall be automatically closed when the HP steam flow is not higher than open permissive value.

This valve shall be protectionally closed if following happen;

* When HP drum level (HAD-90-CL-001/002/003) fall below the low water level (-685 mm from C.L).

2) IP Continuous Blowdwon MOV (HAD-95-AA-002)

The HRSG start up will be initiated with closed blowdown MOV.

The blowdown MOV shall be opened after IP steam flow (LBA-95-CF-001/002) is higher than 20 % MCR flow and also shall be automatically closed when the IP steam flow is not higher than open permissive value.


* When IP drum level (HAD-94-CL-001/002/003) fall below the low water level (-530 mm from C.L).

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2.12 Intermittent Blowdown Control

This valve is used to control the drum level in abnormal condition. If the water level is abnormally high, the intermittent blowdown valves open and the excess volume of water is discharged to the blowdown tank.

1) HP intermittent blowdown MOV (HAD-91-AA-001)

There are two opening set point, namely start up set point and normal set point. The set point change will be done when HP steam production has reached about 25% MCR.

Opening set point;

* Start up set point (below 25% M.C.R); N.W.L (0mm from C.L).

* Normal operation set point (above 25% M.C.R); High water level (+180mm from C.L).

This valve shall be closed whenever drum level fall below set points.

This valve shall have opening limit to prevent excess blowdown flow. When open demand is initiated, the valve open position shall be determined as following.

Opening limit;

* HP Drum Pressure < 15 barg; full open.

* HP Drum Pressure > 15 barg; Intermediate (20%) open.


* When HP drum level (HAD-90-CL-001/002/003) fall below the low water level (-685 mm from C.L).

2) IP intermittent blowdown MOV (HAD-95-AA-001)

There are two opening set point, namely start up set point and normal set point. The set point change will be done when IP steam production has reached about 25% MCR.

Opening set point;




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This valve shall have opening limit to prevent excess blowdown flow. When open demand is initiated, the valve open position shall be determined as following.

Opening limit;

* IP Drum Pressure < 15 barg; full open.

* IP Drum Pressure > 15 barg; Intermediate (20%) open.


* When IP drum level (HAD-94-CL-001/002/003) fall below the low water level (-530 mm from C.L).

3) LP intermittent blowdown MOV (HAD-98-AA-001)

There are two opening set point, namely start up set point and normal set point. The set point change will be done when condensate flow has reached about 25% MCR.

Opening set point;





* When LP drum level (HAD-97-CL-001/002/003) fall below the low water level (-1065 mm from C.L).

2.13 HRSG Feedwater and Condensate line stop MOV

Following valves can be used to make HRSG isolation from the BOP system for HRSG shutdown or maintenance period. The stop valve shall be always opened from HRSG initial start up and not be closed when HRSG is in service.

1) HP Feedwater Main (LAB-90-AA-001) and Bypass (LAB-90-AA-002) stop MOV.

Due to the high pressure difference between the running feedwater pumps and the HRSG, small bypass MOV is provided. As preparation activity for HRSG start, these valves will be used to pressurize the economizer zone by the running feedwater pumps.

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First, the small bypass MOV will be opened. Then, if the pressure difference across the main MOV is less than 5 bar, the main MOV is opened. The small bypass MOV will be closed after the main MOV is fully opened.

These valves shall be protectionally closed if following happen;

* When HP drum level (HAD-90-CL-001/002/003) reaches the High/High water level (230 mm from C.L).

2) IP Feedwater Main (LAB-94-AA-001) and Bypass (LAB-94-AA-002) stop MOV.

Due to the high pressure difference between the running feedwater pumps and the HRSG, small bypass MOV is provided. As preparation activity for HRSG start, these valves will be used to pressurize the economizer zone by the running feedwater pumps.

First, the small bypass MOV will be opened. The, if the pressure difference across the main MOV is less than 5 bar, the main MOV is opened. The small bypass MOV will be closed after the main MOV is fully opened.

These valves shall be protectionally closed if following happen;

* When IP drum level (HAD-94-CL-001/002/003) reaches the High/High water level (230 mm from C.L).

3) Condensate Stop MOV (LCA-90-AA-001)

As preparation activity for HRSG start, this valve will be opened before HRSG start.


* When LP drum level (HAD-97-CL-001/002/003) reaches the High/High water level (725 mm from C.L).

2.14 HRSG Steam line stop MOV

These valves make HRSG isolaton from the steam header in case of HRSG not in service. Also these valves are used to connect the HRSG into the operation steam header during start-up.

During the plant start up, shutdown and trip, pressure builds in the HRSG will be controlled by HP steam bypass system, IP steam line PCV, HRH steam bypass system and LP steam bypass

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system. The HP steam bypass steam will be admitted to the CRH piping. The HRH and LP steam bypass is routed to the condenser respectively.

1) HP Steam Main (LBA-90-AA-003) and Bypass (LBA-90-AA-004) stop MOV.

1.1) For HRSG Start up Mode.

* Lead HRSG HP steam stop MOV ;

The Main stop MOV is opened at the initiation of the HRSG start while the bypass stop MOV is closed. And the HP main steam header is warmed, drained and pressurized along with the HRSG.

* Lag HRSG HP steam stop MOV ;


Temperature difference between lag HRSG steam and operation header steam is lower than 50 deg.C.

The lag HRSG (HP) steam pressure is higher (Approximately, 2 bar) than the operation header pressure.


* Last HRSG HP steam stop MOV ;

The last HRSG HP steam stop MOV’s operation is the same with lag HRSG.

1.2) For HRSG shutdown mode.

* Lead HRSG HP steam stop MOV ;

With HRSG shutdown command, the diverter damper will be closed with normal speed (60 seconds). Then the HP steam bypass system will open to control HP steam pressure and the HRH steam bypass system will open as a result of the HP steam bypass system opening.


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* Lag HRSG HP steam stop MOV ;

The lag HRSG HP steam stop MOV’s operation is the same with lead HRSG.

* Last HRSG HP steam stop MOV ;

During the last unit shutdown, the Steam turbine MCV is ramped closed. The Steam turbine continues to unload and finally the Steam turbine valves are tripped closed. When the ST is tripped, the last HRSG HP and HRH steam stop valves are closed.

2) CRH Steam Stop MOV (LBC-90-AA-001)


* Lead HRSG CRH steam stop MOV ;

The CRH steam stop MOV is opened at the initiation of the HRSG start. And the CRH steam header is warmed, drained and pressurized along with the HRSG.

* Lag HRSG CRH steam stop MOV ;

The lag HRSG reheater is started with closed steam stop valves. Thus, the reheater is initially isolated from the steam header. Steam from the HP steam bypass system passes through the reheater to the condenser via the HRH steam bypass system.

When the steam conditions are satisfied, the lag HRSG HRH steam isolation valve open initiated. At this moment, the CRH steam stop valve will be opened simultaneously.


The last HRSG CRH steam stop MOV’s operation is the same with lag HRSG.


* Lead HRSG CRH steam stop MOV ;

With HRSG shutdown command, the diverter damper will be closed normal speed. Then the HP steam bypass system will open to control HP steam pressure and the HRH steam bypass system will open as a result of the HP steam bypass opening.

The HP steam stop valve will be closed when HRSG shutdown initiated and HP steam bypass system open sufficiently (about 10%). The HP steam bypass set point of the HRSG is slowly ramped below (about 2 bar) the operating pressure, thereby diverting steam from the HP steam through the HP steam bypass system. The lead HRSG HP steam is isolated from the HP header.

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The lag HRSG CRH steam stop MOV’s operation is the same with lead HRSG.

* Last HRSG CRH steam stop MOV ;

During the last unit shutdown, the Steam turbine MCV is ramped closed. The Steam turbine continues to unload and finally the Steam turbine valves are tripped closed. When the ST is tripped and HP steam bypass system is completely closed, the last HRSG CRH steam stop valve is closed.

3) LP Steam Main (LBD-90-AA-002) and Bypass (LBD-90-AA-003) stop MOV.


* Lead HRSG LP steam stop MOV ;

The Main stop MOV is opened at the initiation of the HRSG start while the bypass stop MOV is closed. And the LP main steam header is warmed, drained and pressurized along with the HRSG.

* Lag HRSG LP steam stop MOV ;


Temperature difference between lag HRSG steam and operation header steam is lower than 30 deg.C.

The lag HRSG (LP) steam pressure is higher (Approximately, 0.5 bar) than the operation header pressure.


* Last HRSG LP steam stop MOV ;

The last HRSG LP steam stop MOV’s operation is the same with lag HRSG.


* Lead HRSG LP steam stop MOV ;

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With HRSG shutdown command, the diverter damper will be closed with normal speed. Then the LP steam bypass system will open to control LP steam pressure.

The HP steam stop valve will be closed when HRSG shutdown initiated and HP steam bypass system open sufficiently (about 10%). The HP steam bypass set point of the HRSG is slowly ramped below (about 2 bar) the operating pressure, thereby diverting steam from the HP steam through the HP steam bypass system. The lead HRSG HP steam is isolated from the HP header.


* Lag HRSG LP steam stop MOV ;

The lag HRSG LP steam stop MOV’s operation is the same with lead HRSG.

* Last HRSG LP steam stop MOV ;

During the last unit shutdown, the ST LP control valve is placed in position control and ramped closed. At this moment, the HRSG LP steam stop is closed.

3 HRSG PROTECTION DESCRIPTION The HRSG protection fulfils all requirements to ensure the safe operation with high availability of the HRSG and its main components and the affected/linked plant aggregates. Besides the prevention of personal hazards the HRSG, protection shall avoid failure of major parts of the plant with high financial risk and strong reduction in lifetime of components.

The following items are implemented for HRSG protection.

3.1 HP Drum Level > H.H

The HP drum level is protected against impermissible high water level to avoid water carry over into the superheater, the main steam line and in an extreme case also into the steam turbine. In this case temperature shocks with damages to the superheater and main steam line might occur. Water droplets to the steam turbine might result in mechanical damages to the blades.

1) Signal; High/High(+230 mm from C.L) by 2 out of 3 HP drum level (HAD-90-CL-001/002/003).

2) Actions after time delay of 2 sec;

* HRSG Trip by Fast close of diverter damper.

* Close HP feedwater stop valves (LAB-90-AA-001/002).

* Trip HP/IP feedwater pumps, if the HP feedwater stop valves (LAB-90-AA-001/002) is not closed within 50 seconds.

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3.2 HP Drum Level < L.L

The HP evaporator has to be protected from running dry to avoid local overheating on evaporator due to missing feed water.

1) Signal; Low/Low (-785 mm from C.L) by 2 out of 3 HP drum level (HAD-90-CL-001/002/003).



3.3 IP Drum Level > H.H

The IP drum level is protected against impermissible high water level to avoid water carry over into the superheater, the main steam line and in an extreme case also into the steam turbine. In this case temperature shocks with damages to the superheater and main steam line might occur. Water droplets to the steam turbine might result in mechanical damages to the blades.

1) Signal; High/High (+230 mm from C.L) by 2 out of 3 IP drum level (HAD-94-CL-001/002/003).



* Close IP feedwater stop valves (LAB-94-AA-001/002).

* Trip HP/IP feedwater pumps, if the IP feedwater stop valves (LAB-94-AA-001/002) is not closed within 50 seconds.

3.4 IP Drum Level < L.L

The IP evaporator has to be protected from running dry to avoid local overheating on evaporator due to missing feed water.

1) Signal; Low/Low (-630 mm from C.L) by 2 out of 3 IP drum level (HAD-94-CL-001/002/003).



3.5 LP Drum Level > H.H

The LP drum level is protected against impermissible high water level to avoid water carry over into the superheater, the main steam line and in an extreme case also into the steam turbine. In this case temperature shocks with damages to the superheater and main steam line might occur. Water droplets to the steam turbine might result in mechanical damages to the blades.

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1) Signal; High/High (+725 mm from C.L) by 2 out of 3 LP drum level (HAD-97-CL-001/002/003).



* Close condensate stop valves (LCA-90-AA-001).

* Trip Condensate pumps, if the condensate stop valves (LCA-90-AA-001) is not closed within 50 seconds.

3.6 LP Drum Level < L.L

The LP evaporator has to be protected from running dry to avoid local overheating on evaporator due to missing feed water. The feedwater pumps also have to be protected from cavitations in case of extreme low level of LP drum.

1) Signal; Low/Low (-1165 mm from C.L) by 2 out of 3 LP drum level (HAD-97-CL-001/002/003).



* Trip HP/IP feedwater pumps.

3.7 HP Steam Temperature > H.H

In case of failure of the HP desuperheater steam temperature control, the HRSG has to be protected to avoid impermissible high temp.

1) Signal; High/High (582 deg.C) by 2 out of 3 HP steam temperature (LBA-90-CT-001/002/003)



3.8 Hot Reheat Steam Temperature > H.H

In case of failure of the Reheater desuperheater steam temperature control, the HRSG has to be protected to avoid impermissible high temp.

1) Signal; High/High (581 deg.C) by 2 out of 3 RH steam temperature (LBB-90-CT-001/002/003)


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3.9 HRSG Inlet Duct Temperature > H.H

The HRSG inlet duct has to be protected against impermissible high exhaust gas temperature.

1) Signal; High/High (659 deg.C) by 2 out of 3 Gas temperature (HNA-90-CT-001/002/003)



3.10 HRSG Stack Closure Damper Failure

In case of failure of the HRSG stack damper, the HRSG has to be protected to avoid HRSG duct or HRSG wall over pressurization or rupture caused by closure of the stack damper.

1) Signal; Two out of three open limit switches (HNE-90-CG-081/082/083) do not indicate the stack damper fully open.

2) Actions;


3.11 All HP/IP Feedwater Pumps OFF

In case of failure of all HP/IP feedwater pumps, the HRSG (HP and IP Drum) has to be protected to avoid missing feedwater. 1) Signal; by logic.



3.12 All Condensate Extraction Pumps OFF

In case of failure of all condensate extraction pumps, the HRSG (LP Drum) has to be protected to avoid missing condensate. 1) Signal; by logic.



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3.13 Gas Turbine Trip

In case of a GT trip, the HRSG has also to be tripped to avoid cooling of HRSG by running down GT. 1) Signal; by logic 2) Actions;

* HRSG Trip by Fast close of the diverter damper.

3.14 HRSG Trip Command from C.C.R

HRSG shall be tripped when trip command from C.C.R. decided by the operator. 1) Signal; by logic 2) Actions;


3.15 HRSG Trip and Diverter damper Not Closed

In case that the diverter damper is not closed within required time, the GT shall be tripped. 1) Signal; by logic (The diverter damper is not closed within 20 seconds after HRSG trip initiated). 2) Actions;

* HRSG Trip by the GT trip

3.16 Steam bypass system trip and bypass operation required

In this case the produced HRSG steam cannot be routed completely to the condenser. To avoid steam pressure increase and blowing of the safety valves, the HRSG has to be protected. 1) Signal; by logic. 2) Actions;


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3.17 CW (Circulation Water) System Trip

In this case the produced HRSG steam cannot be routed completely to the condenser due to the lack of condenser vacuum. To avoid steam pressure increase and blowing of the safety valves, the HRSG has to be protected. 1) Signal; by logic. 2) Actions;


4 Alarm and Set Point List Item.

No. Tag.No.

Service

Description Set Point Required Action

1 HNA-90-CT-

001/002/003

HRSG inlet duct

Gas Temperaure

≥ 659 deg.C * Alarm H,H

* HRSG Trip (Time delay 120 sec).

≥ 655 deg.C * Alarm H

* Gas Turbine Run Back until alarm

disappeared.

2 LAB-90-CP-001 HP Econ. Pressure ≥ 210 barg * Alarm H

* Econ. Safety valve Set Pressure.

3 HAD-90-CL-

001/002/003

HP drum level ≥ + 230mm

From Center Line

* Alarm H,H


* Protective close F.W stop MOV

(LAB-90-AA-001/002).

* HP/IP F.W pumps Trip, if F.W stop

MOV is not closed within 50 seconds.

≥ + 180mm

From Center Line

* Alarm H

* Open set point of HP IBD MOV

(HAD-91-AA-001) for Normal

operation.

= 0mm

From Center Line

* Normal Water Level.

* Open set point of HP IBD MOV

(HAD-91-AA-001) for start up

operation.

= - 200mm

From Center Line

* High Start up Water Level, when

Drum Press > 40 barg.

= - 550mm

From Center Line

* Low Start up Water Level, when

Drum Press < 40 barg.

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Item.

No. Tag.No.

Service


≤ - 685mm

From Center Line

* Alarm L.

* Protective close HP CBD MOV

(HAD-91-AA-002) & IBD MOV (HAD-

91-AA-001).

≤ - 785mm

From Center Line

* Alarm L,L


4

HAD-90-CT-001

Vs

HAD-90-CT-002

Wall differential

temperature at HP

Drum lower side.

≥ 50 deg.C * Alarm H.

* limiting GT load change during load

change.

5

HAD-90-CT-003

Vs

HAD-90-CT-004

Wall differential

temperature at HP

Drum upper side.



change.

6 HAD-90-CP-

001/002/003

HP drum pressure ≥ 153 barg * Alarm H.

* Drum Safety valve Set Pressure.

7

HAH-90-CT-008

Vs

HAH-90-CT-009.

or

HAH-90-CT-010

Vs

HAH-90-CT-011.

or

HAH-90-CT-012

Vs

HAH-90-CT-013.

or

HAH-90-CT-014

Vs

HAH-90-CT-015.

Wall differential

temperature at HP

S.H outlet Header.



change.

8 LBA-90-CT-

001/002/003

HP final steam

temperature

≥ 582 deg.C * Alarm H.H




disappeared.

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Item.

No. Tag.No.

Service


= 567 deg.C * Set Point of HP desuperheater

control

9 LBA-90-CP-

001/002/003

HP steam pressure ≥ 146 barg * Alarm H.

* S.H Safety valve Set Pressure.

10 LAE-90-CP-101 Strainer Del.

Pressure on HP

DESH. Spray line

≥ 0.5 bar * Alarm H

* For strainer blocking warning.

11 LBC-90-CP-001 CRH steam

pressure

≥ 42.5 barg * Alarm H.

* CRH Safety valve Set Pressure.

12 LBB-90-CT-

001/002/003

RH final steam

temperature

≥ 581 deg.C * Alarm H.H




disappeared.

= 566 deg.C * Set Point of RH desuperheater

control

13 LBB-90-CP-

001/002/003

Hot RH steam

pressure

≥ 40.5 barg * Alarm H.

* HRH Safety valve Set Pressure.

≥ 39.5 barg * Set point of RH start up vent PCV

control (LBB-90-AA-081)

≥ 39 barg * Open Set point of RH start up vent

isolation MOV (LBB-90-AA-001)

14 LAF-90-CP-101 Strainer Del.

Pressure on RH

DESH. Spray line



15 LAB-94-CP-001 IP Econ. Pressure ≥ 75 barg * Alarm H

* Econ. Safety valve Set Pressure.

16 HAD-94-CL-

001/002/003

IP drum level ≥ + 230mm

From Center Line

* Alarm H,H


* Protective close F.W stop MOV

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Item.

No. Tag.No.

Service


(LAB-94-AA-001/002).

* HP/IP F.W pumps Trip, if F.W stop

MOV is not closed within 50 seconds.

≥ + 180mm

From Center Line

* Alarm H

* Open set point of IP IBD MOV


operation.

= 0mm

From Center Line


* Open set point of IP IBD MOV


operation.

= - 200mm

From Center Line



= - 450mm

From Center Line



≤ - 530mm

From Center Line

* Alarm L.

* Protective close IP CBD MOV

(HAD-95-AA-002) & IBD MOV (HAD-

95-AA-001).

≤ - 630mm

From Center Line

* Alarm L,L


17 HAD-94-CP-

001/002/003

IP drum pressure ≥ 45 barg * Alarm H.


18 LBA-95-CP-

001/002

IP steam pressure ≥ 43 barg * Alarm H.


19 LCA-90-CP-101 CPH Pressure ≥ 40 barg * Alarm H.

* C.P.H Safety valve Set Pressure.

20 LCA-92-CP-101 Strainer Del.

Pressure on CPH

Recirculation Pump



21 LCA-93-CP-101 Strainer Del.

Pressure on CPH

Recirculation Pump



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Item.

No. Tag.No.

Service


22 LCA-90-CT-

003/004

CPH inlet

Temperature

= 70 deg.C * Set Point of CPH recirculaiton temp.

control

≤ 67 deg.C * Alarm L

23 LCA-94-CF-

001/002

CPH Recirculation

flow

≥ 330,000 kg/hr * Alarm H.H

* Stop the operation pump and Start

the standby pump.

≥ 300,000 kg/hr * Alarm H.

* Limit further opening of TCV(LCA-

94-AA-081).

≤ 65,000 kg/hr * Alarm L.

* Limit further closing of TCV(LCA-94-

AA-081).

≤ 60,000 kg/hr * Alarm L.L

* Stop the operation pump and Start

the standby pump.

24 HAD-97-CL-

001/002/003

LP drum level ≥ + 725mm

From Center Line

* Alarm H,H


* Protective close Condensate stop

MOV (LCA-90-AA-001).

* Condensate extraction pumps Trip,

if Condensate stop MOV is not closed

within 50 seconds.

≥ + 680mm

From Center Line

* Alarm H

* Open set point of LP IBD MOV


operation.

= + 500mm

From Center Line


* Open set point of LP IBD MOV


operation.

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Item.

No. Tag.No.

Service


= + 300mm

From Center Line



= - 100mm

From Center Line



≤ - 1065mm

From Center Line

* Alarm L.

* Protective close LP IBD MOV (HAD-

98-AA-001).

≤ - 1165mm

From Center Line

* Alarm L,L


* HP/IP feedwater pumps Trip.

25 HAD-97-CP-

001/002/003

LP drum pressure ≥ 10 barg * Alarm H.


≥ 7 barg * Protective close pegging stop MOV

(LBA-96-AA-001).

= 3 barg * Set Point of LP Drum pegging

control

26 LBD-90-CP-

001/002/003

LP steam pressure ≥ 9 barg * Alarm H.


≥ 8 barg * Set point of LP start up vent PCV control

(LBD-90-AA-081)

≥ 7.5 barg * Open Set point of LP start up vent

isolation MOV (LBD-90-AA-001)

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5 HRSG Water Chemistry Requirements The main objectives of water chemistry control are to insure the long term integrity of the materials of construction and the successful operation of the water & steam cycle. The particular types of chemical treatment may vary depending on many factors such as the variety of materials, operating conditions, system design, etc.

These guidelines are generally in accordance with published guidelines from EPRI, VGB, ASME, as well as ABMA (American Boiler Manufacturers Association).

- Demineralized Water (at Demineralizer Water Plant Outlet)

Target (See table for Maximum Annual Exposure to

Contaminant Conditions and Action Level Criteria) Parameter Unit Normal

Specific conductivity μS/cm < 0.2

Silica as SiO2 ppb < 20

Sodium + Potassium as Na+K ppb < 10

Iron as Fe ppb < 20

Copper as Cu ppb < 3

TOC ppb < 300

- Condensate (at Condensate Pump Discharge)


Contaminant Conditions and Action Level Criteria) Parameter Unit Normal Level 1 Level 2 Level 3

Cation Conductivity μS/cm < 0.2 < 0.4 < 0.8 > 0.8

pH-value - 9.0 - 9.6 - - -

Silica as SiO2 ppb < 20 > 20 - -

Iron as Fe ppb < 20 > 20 - -

Sodium as Na ppb < 10 < 20 < 40 >40

Copper as Cu ppb < 3 > 3 - -

Oxigen ppb < 10 < 20 > 20 -

- Feedwater (at Feedwater pump Discharge)

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Contaminant Conditions and Action Level Criteria) Parameter Unit Normal Level 1 Level 2 Level 3

Cation Conductivity μS/cm < 0.2 < 0.4 < 0.8 > 0.8

pH-value - 9.0 - 9.6 - - -

Silica as SiO2 ppb < 20 > 20 - -

Iron as Fe ppb < 20 > 20 - -

Sodium as Na ppb < 10 < 15 < 30 >30

Copper as Cu ppb < 3 > 3 - -

Oxigen ppb < 10 < 15 < 20 >20

- Boiler Water (HP, IP and LP Drum)

Note: These guidelines do not apply to the Low Pressure (LP) drum because LP drum acts as a feedwater tank. In such a case, the feedwater guidelines are applicable to the LP boilerwater.


Contaminant Conditions and Action Level Criteria) Parameter Unit Normal Level 1 Level 2 Level 3 Immediate

shutdown

Specific Conductivity (HP drum) μS/cm < 40 < 50 > 50 - -

Cation Conductivity (HP drum) μS/cm < 30 < 40 > 40 - -

pH-value (HP drum) - 9.1 - 9.6 - - - < 8

Silica as SiO2 (HP drum) ppm < 0.6 < 1.2 < 2.4 > 2.4 -

Phosphate as PO4 (HP drum) ppm < 6 < 8 < 15 > 15 -

Specific Conductivity (IP drum) μS/cm < 50 < 60 > 60 - -

Cation Conductivity (IP drum) μS/cm < 40 < 50 > 50 - -

pH-value (IP drum) - 9.1 - 9.6 - - - < 8

Silica as SiO2 (IP drum) ppm < 7 < 10 < 20 > 20 -

Phosphate as PO4 (IP drum) ppm < 6 < 8 < 15 > 15 -

- Maximum Annual Exposure to Contaminant Conditions and Action Level Criteria

Targets Cumulative Hours per Year Action Level Criteria

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Qurayyah CCPP HRSG


Base Load Cycling

Normal - - Values are consistent with long-term reliability.

Action Level 1 336 (2 weeks) 672 (4 weeks) There is a potential for the accumulation of

contaminants and corrosion. Return values to

normal levels within 1 week.

Action Level 2 48 (2 days) 96 (4 days) The accumulation of impurities an corrosion will

occur. Return values to normal levels within 24

hours.

Action Level 3 8 16 Experience indicates that rapid corrosion could

occur, which can be avoided by shutdown of the

unit within 4 hours.

Immediate

shutdown

1 2 There is clear evidence of rapid boiler tube

damage by low boiler water pH. Immediate

shutdown of the unit is required to avoid such

damage.

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hrsg.pdf

Documents

qurayyah plant

combined cycle operation

combustion gas turbine

open cycle operation

qurayyah ccpp hrsg chapter

gas turbines

produced steam

exhaust gas diverter