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TRAINING REPORT

  SA.SANTHOSH  SUMMER TRAINEE

2011

SRM UNIVERSITY

 

CONTROL & INSTRUMENTATION PROJECT

ENGINEERING MANAGEMENT BHEL, NOIDA

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ACKNOWLEDGEMENT

I take this opportune moment to express my deep sense of gratitude to

Mr. KAMAL SHARMA (ENGINEER C&I) for his unstinted support

and encouragement to me. I express my heartfelt thanks to the

Department Head Mr. K.R. BHARADWAJ (C&I) and Mr.

S.BHATNAGAR (Section Head – I01, C&I) for being a source of 

guidance and inspiration for me during this period. Their wonderful style

of mentoring has surely made my training period a great learning

experience. I would also like to offer my indebtedness to Mr. Kamal

Kumar (ENGINEER C&I) for his ever willingness to extend technical

support through out this period. I express my sincere thanks to all the

members of C&I Dept. for their friendly and helpful attitude.

29.06.11

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ABSTRACT

The purpose of this report is to give a brief idea about what has

been done in the training. This report comprises of various

activities/orientation programmes constituting the training.

Broadly, the various activities which made a part of our training

were PEM familiarization, familiarization with work 

particularly in C&I and finally the day to day learning of the

routine work in the department.

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TABLE OF CONTENTS

ACKNOWLEDGEMENT 3

ABSTRACT 4

1. About the Company 6

2. About the Department 8

3. Role of C&I 9

4. Overview of power plant 10

5. P&ID-Introduction 18

6. KKS Identification Scheme 19

7. Instrument Schedule 20

8. Control System 22

8.1 Binary Control System 26

8.1.1 Sequence Control Scheme 28

9. Conclusion 37

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About The Company

BHEL is the largest engineering and manufacturing enterprise in India in the

energy related/infrastructure sector, today.

BHEL’s vision is to become a world class engineering enterprise, commited to

enhance stakeholder value. The company is striving to give shape to itsaspirations and fulfill the expectation as a ‘Navratna’ Company.

BHEL manufactures over 180 products under 30 major product groups and

caters to core sectors of the Indian Economy viz., Power Generation &

Transmission, Industry, Transportation, Telecommunication, Renewable

Energy, etc.

The wide network of  BHEL's 15 manufacturing divisions, four Power Sector

regional centres, over 100 project sites, eight service centres and 18 regionaloffices, enables the Company to promptly serve its customers and provide them

with suitable products, systems and services efficiently and at competitive

prices.

The high level of quality & reliability of its products is due to the emphasis on

design, engineering and manufacturing to international standards by acquiring

and adapting some of the best technologies from leading companies in the

world, together with technologies developed in its own R&D centres.

BHEL has acquired certifications to Quality Management Systems (ISO 9001),

Environmental Management Systems (ISO 14001) and Occupational Health &

Safety Management Systems (OHSAS 18001) and is also well on its journey

towards Total Quality Management.

BHEL has:

• Installed equipment for over 100,000 MW of power generation for utilities,

captive and industrial users.

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• Supplied over 2,25,000 MVA transformer capacity and sustained

equipment operating in transmission & distribution network up to 400 KV

AC & DC.

• Supplied over 25,000 motors with Drive Control System to Power project,

Petrochemicals, Refineries, Steel, Aluminium, Fertilizer, Cement plant etc.• Supplied Traction electrics and AC/DC losses to power over 12,000 Kms

Railway network.

• Supplied over one million values to Power Plants and other industries.

BHEL’s operations are organized around three business sectors, namely:

Power, Industry including Transmission, Transportation, Telecommunication

& Renewable Energy and

Overseas Business.

This enables BHEL to have a strong customer orientation, to be sensitive to his needs

& to respond quickly to the changes in the market.

The greatest strength of BHEL is its highly skilled and committed 46,848 employees.

Every employee is given an equal opportunity to develop himself and grow in his

career. Continuous training and retraining, career planning, a positive work culture

and participative style of management. All these have engendered development of a

committed and motivated workforce setting new benchmarks in terms of productivity,

quality and responsiveness.

Project Engineering Management

Project Engineering Management Division (PEM) is a division within

the power group to provide total Systems Engineering for BHEL

equipment, as well as for procurement, erection & commissioning of non

BHEL systems & equipment for thermal power stations.

BHEL business is in the field of power generation equipment, which is

handled by the Power Group and covers all the services related to power

projects from concept to commissioning in keeping with the corporate

aim of developing BHEL into a world class engineering organization.

Power Generation Sector comprises thermal, gas, hydro and nuclear

power plant business. As of 31.3.2006, BHEL supplied sets account for

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76,741 MW or nearly 65 percent of the total installed capacity of 

1,18,561 MW in the country, as against Nil till 1969 70.

In view of the high degree of technical excellence achieved, there is an

ever increasing participation in National & International Power Projects.

About The Department

Name of the department: Control & Instrumentation(C&I) 

Instrumentation & control is widely used collective term covering two

distinct aspects of plant operation. Instruments are those items attached to

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a plant, which gives an indication to the operator of the conditions that

exists within the safety limits & operational parameters for which the

plant was designed. Examples of indicative quantities are operating

pressures, temperatures, flows & level etc.

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Role of Control & Instrumentation (C&I)

INTRODUCTION

The main objective of C&I is to select & mark the proper instruments on process

diagrams, prepare the list of instruments, control logics (analog& binary),

control room layout, cable schedule, cable termination details etc. In C&I

dept. plant schematics are prepared by using Auto Cad software for

implementation on CRT’s for control & monitoring the plant by their

electronics division namely BHEL EDN Bangalore (sister unit).

All control logics are also being translated to software i.e. max–DNA control system

by BHEL EDN.The “unit overview” scheme shows the various equipments of the plant & Main

operating process parameters which are real time parameters in nature & all the

indications related to temperature, pressure, flow, levels etc. are displayed

automatically on CRTs, in case of some fault or malfunctioning the automatic alarm is

blinked on CRT for operator’s action in main control room.

C&I ENGINEERING OUTPUTS

1. Design philosophy for C&I.

2. Design philosophy for HMI.

3. Analog/Binary drive control philosophy.

4. Alarm.

5. Power supplies.

6. Cabling philosophy.

7. Control panels arrangement/locations and UCB

8. Marking of Instruments on P&ID’s .9. Instrument Schedule.

10. Root Valve Schedule.

11. Drive List.

12. Binary/Sequence Control Logic Diagrams including Unit

Integrated Scheme.

13. Analog Control and Measuring Schemes.

14. I/O List (Analog and Digital).

15. Control Valve data sheet.

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16. Flow element data sheet.

17. SWAS(Steam and Water Analyser System).

18. Technical specification and BOM.

19. Control room and SWAS layout.

Overview of Power Plant

THERMAL POWER PLANT

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A thermal power station near Sofia, Bulgaria

A thermal power station comprises all of the equipment and systems

required to produce electricity by using a steam generating boiler fired

with fossil fuels or biofuels to drive an electrical generator. Some prefer

to use the term energy center  because such facilities convert forms of 

energy, like nuclear energy, gravitational potential energy or heat energy

(derived from the combustion of  fuels) into electrical energy. However,

  power plant is the most common term in the United States, while power 

station prevails in many Commonwealth countries and especially in the

United Kingdom.

Such power stations are most usually constructed on a very large scale

and designed for continuous operation.

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 Diagram of a typical coal fired thermal power station

Typical diagram of a coal fired therm- al power station

1. Cooling tower10. Steam control

valve19. Superheater

2. Cooling water pump11. High pressure

steam turbine

20. Forced draught

(draft) fan

3. Three phase  

transmission line12. Deaerator 21. Reheater

4. Step up transformer 13. Feedwater heater22. Combustion air

intake

5. Electrical generator 14. Coal conveyor 23. Economiser

6. Low pressure steam

turbine15. Coal hopper 24. Air preheater

7. Boiler feedwater pump 16. Coal pulverizer 25. Precipitator

8. Surface condenser 17. Boiler steam drum26. Induced draught

(draft) fan

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9. Intermediate pressure

steam turbine18. Bottom ash hopper 27. Flue gas stac k  

Steam generator

Schematic diagram of typical coal fired power plant steam generator

highlighting the air preheater (APH) location. (For simplicity, any radiant

section tubing is not shown.)

The steam generating boiler has to produce steam at the high purity,

pressure and temperature required for the steam turbine that drives the

elecrical generator. The generator includes the economizer, the steam

drum, the chemical dosing equipment, and the furnace with its steam

generating tubes and the superheater coils. Necessary safety valves are

located at suitable points to avoid excessive boiler pressure. The air and

flue gas path equipment include: forced draft (FD) fan, air preheater 

(APH), boiler furnace, induced draft (ID) fan, fly ash collectors (electric 

precipitator or baghouse) and the flue gas stack .

For units over about 200 MW capacity, redundancy of key components isprovided by installing duplicates of the FD fan, APH, fly ash collectors

and ID fan with isolating dampers. On some units of about 60 MW, two

boilers per unit may instead be provided.

Boiler furnace and steam drum

The boiler furnace auxiliary equipment includes coal feed nozzles and

igniter guns, soot blowers, water lancing and observation ports (in the

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furnace walls) for observation of the furnace interior. Furnace explosions 

due to any accumulation of combustible gases after a trip out are avoided

by flushing out such gases from the combustion zone before igniting the

coal.

The steam drum (as well as the superheater coils and headers) have air

vents and drains needed for initial startup. The steam drum has internal

devices that removes moisture from the wet steam entering the drum from

the steam generating tubes. The dry steam then flows into the superheater

coils.

Fuel preparation system

In coal fired power stations, the raw feed coal from the coal storage area

is first crushed into small pieces and then conveyed to the coal feed

hoppers at the boilers. The coal is next pulverized into a very fine

powder. The pulverizers may be ball mills, rotating drum grinders, or

other types of grinders.

Some power stations burn fuel oil rather than coal. The oil must kept

warm (above its pour point) in the fuel oil storage tanks to prevent the oil

from congealing and becoming unpumpable. The oil is usually heated to

about 100°C before being pumped through the furnace fuel oil spray

nozzles.

Boilers in some power stations use processed natural gas as their main

fuel. Other power stations may use processed natural gas as auxiliary fuel

in the event that their main fuel supply (coal or oil) is interrupted. In such

cases, separate gas burners are provided on the boiler furnaces.

Fuel firing system and igniter system

From the pulverized coal bin, coal is blown by hot air through the furnace

coal burners at an angle which imparts a swirling motion to the powdered

coal to enhance mixing of the coal powder with the incoming preheated

combustion air and thus to enhance the combustion.

To provide sufficient combustion temperature in the furnace before

igniting the powdered coal, the furnace temperature is raised by first

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burning some light fuel oil or processed natural gas (by using auxiliary

burners and igniters provide for that purpose).

Air path

External fans are provided to give sufficient air for combustion. The

forced draft fan takes air from the atmosphere and, first warming it in the

air preheater for better combustion, injects it via the air nozzles on the

furnace wall.

The induced draft fan assists the FD fan by drawing out combustible

gases from the furnace, maintaining a slightly negative pressure in the

furnace to avoid backfiring through any opening. At the furnace outlet,and before the furnace gases are handled by the ID fan, fine dust carried

by the outlet gases is removed to avoid atmospheric pollution. This is an

environmental limitation prescribed by law, and additionally minimizes

erosion of the ID fan.

 Auxiliary systems Fly ash collection 

Fly ash is captured and removed from the flue gas by electrostatic

precipitators or fabric bag filters (or sometimes both) located at the outlet

of the furnace and before the induced draft fan. The fly ash is periodically

removed from the collection hoppers below the precipitators or bag

filters. Generally, the fly ash is pneumatically transported to storage silos

for subsequent transport by trucks or railroad cars.

 

Steam turbine driven electric generator

 The steam turbine driven generators have auxiliary systems enabling

them to work satisfactorily and safely. The steam turbine generator being

rotating equipment generally has a heavy, large diameter shaft. The shaft

therefore requires not only supports but also has to be kept in position

while running. To minimise the frictional resistance to the rotation, the

shaft has a number of  bearings. Oil lubrication is provided to further

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reduce the friction between shaft and bearing surface and to limit the heat

generated.

Condenser

Diagram of a typical water cooled surface condenser-

The surface condenser is a shell and tube heat exchanger in which cooling

water is circulated through the tubes. The exhaust steam from the low

pressure turbine enters the shell where it is cooled and converted to

condensate (water) by flowing over the tubes as shown in the adjacentdiagram.Such condensers use steam ejectors or rotary motor-driven exhausters forcontinuous removal of air and gases from the steam side to maintainvacuum.The condenser generally uses either circulating cooling water from acooling tower or once-through water from a river, lake or ocean. 

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DEARATOR

Diagram of boiler feed water deaerator (with vertical, domed aerationsection and horizontal water storage section

A steam generating boiler requires that the boiler feed water should be

devoid of air and other dissolved gases, particularly corrosive ones, in

order to avoid corrosion of the metal.

Generally, power stations use a deaerator to provide for the removal of 

air and other dissoved gases from the boiler feedwater. A deaerator

typically includes a vertical, domed deaeration section mounted on top of 

a horizontal cylindrical vessel which serves as the deaerated boilerfeedwater storage tank.

There are many different designs for a deaerator and the designs will vary

from one manufacturer to another. The adjacent diagram depicts a typical

conventional trayed deaerator. If operated properly, most deaerator

manufacturers will guarantee that oxygen in the deaerated water will not

exceed 7 ppb by weight (0.005 cm³ /L).

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OTHER SYSTEMS :

Monitoring and alarm system

All of the major plant components and systems require pre checking for

start up during the first start or after a shut down for any reason

whatsoever. The safety aspects and the normal procedures have to be

looked into at all stages of operation. Manual intervention is also

unavoidable; however, much the system is made automatic. In view of 

this necessary protection, monitoring with alarms for out of limit

parameters, and auto and manual control equipment are provided on theoperator consoles, both on the mechanical and electrical equipment.

 

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P&ID- INTRODUCTION

(PROCESS & INSTRUMENTATION DIAGRAM)

A piping and instrumentation diagram/drawing (P&ID) is defined by asfollows:

A diagram which shows the interconnection of process equipment and theinstrumentation used to control the process. In the process industry, astandard set of symbols is used to prepare drawings of processes.

P&IDs play a significant role in the maintenance and modification of theprocess that it describes. It is critical to demonstrate the physical sequence

of equipment and systems, as well as how these systems connect. Duringthe design stage, the diagram also provides the basis for the developmentof system control schemes.

For processing facilities, it is a pictorial representation of

• Key piping and instrument details

• Control and shutdown schemes• Basic start up and operational information

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KKS  (Kraftwerk Kennzeichen system)

  POWER PLANT IDENTIFICATION SYSTEM 

The KKS Power Plant Classification Systemis a standardised system

for the classification of power stations. It serves during engineering,

construction, operation and maintenance of power stations for

identification and classification of the equipment. The system is known in

short as KKS which is the abbreviation of the German term. KKS will be

replaced in future by Reference Designation System for Power Plants,

RDS PP. RDS PP has almost same structure as KKS 90 % of the code

letters in the function key, other keys much less.  

Contents

1 Structure and Format

2 Examples of codes

3 Function Key (Main Groups)

4 Function Key (Main Groups and Subgroups)

5 Equipment Unit Key (Main Groups)

6 Equipment Unit Key (Main Groups and Subgroups)

7 Component Key (Main Groups)

8 Standards and further development

9 External links

Structure and Format

The KKS has three different types of codes:

Process related code , for identification of systems and equipment

according to their functions in the power station process.

Point of installation code, for identification of points of installation of 

electrical ,control and instrumentation devices

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Location code, for identification of locations of equipment and

structures.

INSTRUMENT SCHEDULE

An instrument schedule is a list of instruments in a P&ID This list

describes all parameters of the instrument and contains following

information of each instrument.

1. Serial Number

2. Tag No (KKS Number)

3. Status

4. Type of Field instrument(level, Pressure, Flow etc)

5. Medium

6. Range

7. Set point

8. Operating parameters

9. DDCMIS control

10. Reference P&ID number

11. Srvice Description

1. KKS Number:

This column contains the unique KKS number assigned to theinstrument.

2. Field Instrument:

This column is further divided into two columns: one describing the

type of the instrument (Eg. LT: Level Tx, Cr Al: Bimetallic Strip

etc.) and the other gives the name of the division of BHEL under

whose scope this instrument is covered (Eg. EDN: BHEL EDN)

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3. Medium:

This describes the medium that the instrument is designed to

measure the property of. Eg. Water, steam, DM water, air etc.

4. Range:

This states the range of values that the instrument is designed to

measure.

5. Operational Parameters:

This shows the temperature and pressure of the medium that is

flowing through the instrument and is designed to measure.

6. DDCMIS:

This column shows what the output of the different instruments is

going to be at different points of time in the control system. It also

controls the working of the alarm depending upon the output of the

different instruments.

7. Reference P&ID No.:

This column shows the P&ID no. of the drawing on which the

particular instrument is used.

8. Description:

It gives a brief description where the particular instrument is present

and what it is going to measure or control.

 

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CONTROL SYSTEM

NEED FOR AUTOMATIC CONTROL 

The Power Generating Plant's behavior can be seen by observing certain

physical parameters, which are the characteristics of the plant processes.

The important process parameters are temperature, pressure, flow; fluid

levels, rotating speeds etc. The measured values of the most significant of

these parameters are transmitted from the plant to a Central Control

Room (CCR) where these are indicated to an operator.

If the plant is to be operated at designed optimum conditions, the

measured values of each of the characteristic parameters has to be

maintained as close as possible to desired value. These requirements are

met by regulating the plant processes using process equipments like

Valves, Dampers, servo motors etc. so that the deviations of the measured

values of characteristic parameters from their desired values may be

corrected. This is done with the help of push buttons, CRT station,

controllers etc.

Due to fast varying load demands and also the inter-relationship of

behavior of various components, operator is unable to take decisionscorrectly in the short time available to him. Auto control systems provide

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solutions for such situations. Further, many subsystems have complexity

in Start/Stop/Running e.g. BFP, CEP etc in terms of safe conditions to

start, conditions for tripping the machine for process/equipment

protection.

High capital cost of modern day power plant necessitates its having

extended life cycle. To obtain this, flexibility, efficient and safe operation,

substantial degree of Automatic Control is required to be built in.

There are two types of Control systems:

• Closed loop control System (Analog control Schemes)

• Open Loop Control System (Binary control Schemes)

CLOSED LOOP CONTROL: 

System utilizes feedback to measure the actual system operating

parameter being controlled such as press, temp, flow etc. The feedback

signal is sent back to the controller where it is compared with the desired

system set point. The controller develops an demand signal that initiates

corrective action and drives the final output device to obtain desired

process value.

OPEN LOOP CONTROL:

No feedback loop is employed and system output is given to the field

devices (motors, pumps etc) The interlocks and protections are built-in

the control systems.

Closed Loop systems have the following features:

• Controller compares the system reference with the system feedback

& generates the error signal.

• Set point establishes the desired operating point around which the

system should operate.

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• Feedback signal informs the controller of the operating point of

system (process measurement).

• Final Control Element responds to the system demand to bring the

desired process value.

• Tuning elements provide system stabilization & adjust system

response time. These are Proportional, Integral, Derivative

functions.

PROPORTIONAL CONTROL

This is primary alternative to ON/OFF control. The output is proportional

to the difference between the Desired value and the measured value.

P* (Desired – Current)

P is a constant proportional gain set by the designer. This shall determine

the time taken by the plant to reach new SP (Overshoot or Undershoot is

minimized).

The biggest problem with Proportional Control alone is that you want to

reach desired output quickly & avoid overshoot and minimize ripple. We

can derive the information of the rate of change of plant O/P. If the output

is changing rapidly, overshoot or undershoot may lie ahead. In such cases

we can reduce the size of change suggested by Proportional Controller.

PROPORTIONAL-DERIVATIVE CONTROL

The rate of change of a signal is known as its Derivative. The Derivative

at the current time is change in value from the previous sample to the

current one.

D* (Current - Previous)

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D is a constant Derivative gain. PD controllers work well in practice. The

net effect is slower response time with far less overshoot & ripple than P

controller alone.

INTEGRATION CONTROL

PD alone may not be enough if individual error remains below the

threshold for action by the proportional term.

I* E(Desired – Current)

An integral is a sum of all past errors in the plant output. Even though

integral gain factor is small, persistent error will cause the integral term to

force a change in the drive signal.

To sum it all ON-OFF and PROPORTIONAL control are two basic

techniques of CLCS.

However, DERIVATIVE and/or INTEGRAL terms are added to

Proportional controls to improve the qualitative property of plant

response.

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BINARY CONTROL SCHEMES

1 FD FAN A CONTROL SYSTEM

1. The steam generators supplied today are larger in size and sophisticated in nature.Failure of any equipment calls for expensive replacement and results in costlier downtime. This emphasises careful planning on the correct procedure for;

1. Safe sequence of start-up of equipments in the power plant.2. Continuous trouble free & efficient operation.3. Safe sequence of shutdown of the equipment when needed.

This also leads to provision of adequate & reliable protection to safeguard the variousplant equipments under abnormal and dangerous conditions. The operation of theprotections shall be accompanied by visual and audible annunciation, which providedefinite indication of the primary cause or causes of operation of the protection.Restarting of the equipment, which has once been tripped by protection either by remote,automatic or manual control shall be possible only after the elimination of the cause oftripping.

FD FAN INTERLOCKS

1.1 Conditions prior to starting FD fans:a) FD Fan A and FD Fan B offb) Fan blade pitch control tilted to maximum openingc) Outlet dampers are fully opend) Fan blade pitch control regulator disconnectede) Lube oil pumps of FD fans off

1.2 Starting FD fan A (FD fan B is off):

a) FD Fan A shall be prohibited from starting until the following conditions are satisfied:i. ID Fan A or ID Fan B is on

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ii. Fan A blade pitch in the minimum positioniii. Outlet damper of fan A in closed positioniv. Fan/motor bearing temperature not very highv. Motor winding temperature not very highvi. Lube oil system permissives satisfied (Ref. Clause 6.0)

b) When FD fan A is started (FD Fan B is off) impulses shall be given for:i. Outlet gate of fan A to open after the motor reaches rated speedii. The outlet damper of FD fan B to close & blade pitch control of fan B to be driven tominimum positioniii. Connecting the blade pitch control of Fan A control drive to auto control

1.3 Starting of FD fan B (FD fan A is off):Interlocks similar to those at clause 2.2 shall hold good for this condition.

1.4 Tripping of FD fan A (FD fan B is off)a) FD fan A shall trip automatically under the following conditions:i. FD fan A bearing temperature too high (prior to this, FD fan A bearing temperature high

 will be annunciated in DDCMIS)ii. FD fan A motor bearing/winding temperature too high (prior to this, FD fan A motorbearing/ winding temperature high will be annunciated in DDCMIS)iii. Both ID fans tripiv. Post purge fan tripv. Vibration level of fan or motor very high (high to be alarmed). For fan, trip shall beinitiated with a delay of 10 minutes during starting and running of fan.

b) When FD Fan A trips (FD fan B is off) impulses shall be given for:i. Disconnecting the blade pitch control drive from auto control system (output signal fromA/M station)ii. Bringing the blade pitch of Fan A to the maximum position

iii. Bringing the blade pitch of FD fan B to the maximum positioniv. Opening the outlet damper of FD fan Bv. To open the emergency scanner air dampervi. Boiler trippingvii. The outlet damper of FD fan A shall remain open.

1.5 Tripping FD fan B (FD fan A is off):Interlocks similar to those of clause 2.4 shall hold good for this condition

1.6 Starting FD fan B (FD fan A is on):a) FD fan B (FD fan A is on) shall be prohibited from starting until the following conditionsare satisfied:i. Two ID fans are onii. Fan B blade pitch control in the minimum positioniii. Outlet damper of Fan B in closed positioniv. Fan and fan motor bearing temperature not very highv. Motor winding temperature not very high.vi. Lube oil system permissive satisfied (Ref. Clause 6.0)

b) When FD fan B is started (FD fan A is on) impulses shall be given for:i. Opening the outlet damper of FD fan B after the motor reaches rated speedii. Connecting the blade pitch control drive of FD fan B to auto control

1.7 Starting FD fan A (FD fan B is on):Interlocks similar to those at clause 2.6 shall hold good for this condition.

1.8 Tripping of FD fan B (FD fan A is on):

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(a) FD fan B shall trip (when FD fan A is on) under the following conditions:i. ID fan B tripsii. FD fan B motor bearing/winding temperature too high (prior to this, FD fan B motorbearing/winding temperature high shall be annunciated in DDCMIS)iii. FD fan B bearing temperature too high (prior to this, FD fan B bearing temperaturehigh shall be an annunciated in DDCMIS)

iv. Vibration level of fan or motor very high (high to be alarmed). For fan, trip shall beinitiated with a delay of 10 minutes during starting and running of fan.b) When FD fan B trips (FD fan A is on), impulses shall be given for:i. Disconnecting regulating impulse from acting on blade pitch control drive of fan Bii. Bringing blade pitch control of fan B to the minimum positioniii. Closing the outlet damper of fan Biv. Reducing boiler load to 50% MCR.v. Tripping coal elevation in service more than four through FSSS

2 INTERLOCKS FOR FD FAN LUBRICATING OIL SYSTEM:

2.1 FD fan A lube oil system:a) Pump A will start automatically if pump B trips provided A/M switch is in auto position

b) Pump A will start automatically with a time delay of 30 seconds if lube oil pressure fallsbelow a set value and the pump B is working provided A/M switch is in auto position.c) Pump B will start automatically if pump A trips/has not started provided A/M switch is inauto position.d) Pump B will start automatically with a time delay of 30 seconds if lube oil pressure fallsbelow a set value and the pump A is working provided A/M switch is in auto position.e) Pump A or pump B can be started/tripped by pressing the respective push buttonprovided on local pushbutton box when A/M switch is in manual position.f) FD fan A shall be prohibited from starting until the lube oil pressure is adequate.g) Both lube oil pumps shall be switched OFF automatically after a delay of 30 min. afterthe FD fan A is OFF.

 2.2 FD fan B lubricating oil system:Interlocks similar to those at 6.1 (a) to (g) above shall hold good for FD fan B lubricatingoil system.

Note:

An alarm shall be initiated for the following conditions:

− after a time delay of 2 min. when both Lube oil pumps of a FD fan are running.

−  when the lube oil tank level is low.

− DP across lube oil filter is high.

− Lube oil pressure is less than set value.

 2.3 Tripping of FD fan A (FD fan B is on):

Interlocks similar to those at clause 1.8 shall hold good for this condition.Note: When the control oil pressure is less than the set value, the corresponding FD fanregulating device shall remain in stayput position. This is to be taken care in auto-controlsystem.

8.1.1 Sequence Control Scheme FD Fan A

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  P&ID Air & Flue gas path

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CONCLUSION

Power plant control system is the nucleus of a power plant operation.

The reduction of operating time through the management of daily and

periodic operation, improvement and ease of maintenance, and improved

efficiency while reassuring reliability and safety are all merits of power

plant control systems.

Project Engineering Management, being the core engineering division for

design of power plant is a great platform to start the process of learningabout the power industry and the technical aspect of power plants. This

division is a hub of learning and engineering activity which enables

overall understanding and provides a summate view of a power plant.

Being part of Control & Instrumentation has enabled me to get an overall

picture of the power plant functioning and management. C&I engineering

touches almost all parts of a power plant and this makes the area of work 

very vast and interesting. Power plant automation has become a very

challenging and dynamic field.

Advanced communication networks have helped the growth of power

plant automation in a phenomenal manner. The speed with which signals

flow between processors in control room and various distributed control

locations in power plant has made it possible to automate almost the

entire power plant. The advancement in the technology of transmitter and

valve actuators has simplified the overall power plant control system.

State of the art automation and control systems guarantee the simple and

the safe operation of steam power plant. The overall control of the plant

takes care of operational regulations as well as the primary systems. This

requires an integrated control of these parts. All process signals should be

managed without multiple engineering. In order to allow an easy future

expansion, the local and remote communication of the system has to be

based on modular technology.

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In the changing social scenario, continuous demand of power has made

longer down time of power plant impossible. This in turn has made the

  job of power plant automation very demanding. The failures of 

equipments have to be either prevented or be reported immediately. This

all is leading to a rise in the challenges of power plant automation.

The challenge is not only towards the automation of new plants but there

is an additional challenge to modernize the control system of the existing

plants.