neptune chs lpg user manual · 2018-10-30 · kongsberg maritime doc.no.: so-1407-c / 26-oct-10...

Kongsberg Maritime

Doc.no.: SO-1407-C / 26-Oct-10

Neptune CHS LPG User Manual

Neptune CHS

LPG Liquefied Petroleum

Gas Carrier

User’s Manual

Department/Author: Approved by:

___________________ ____________________

Steffen Hårstad Jensen (s) Terje Heierstad (s)

2012 KONGSBERG MARITIME AS

All rights reserved

No part of this work covered by the copyright

hereon may be reproduced or otherwise copied

without prior permission from

KONGSBERG MARITIME AS

Kongsberg Maritime

Doc.no.: SO-1407-C / 26-Oct-10

Neptune CHS LPG User Manual i

DOCUMENT STATUS

Issue No. Date/Year Inc. by Issue No. Date/Year Inc. by

SO-1407-A 9-Oct-08 STHJ/beba

SO-1407-B 14-Apr-09 STHJ/beba

SO-1407-C 26-Oct-10 STHJ/beba

CHANGES IN DOCUMENT

Issue ECO Paragraph Paragraph Heading/

No. No. No. Description of Change

B MP-1693 Upgrade, New Pictures & functionality

C MP-1728 Text improvements, clarifications of

refrences to real vessel, picture updates

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ii Neptune CHS LPG User Manual

Hazard Warnings

And Cautions

Fire

If a fire condition arises emission of toxic fumes can be

anticipated from burning insulation, printed circuit boards,

ETC.

Dangerous Voltages

This equipment is not fitted with safety interlocks and lethal

voltages are exposed when the cabinets are open. Before

removing any sub-units or component all supplies must be

switched off. No user serviceable parts inside.

Electrostatic sensitive device

Certain semiconductive devices used in this equipment are

liable to damage due to static voltage. Observe all precautions

for handling of semiconductive sensitive devices.

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Neptune CHS LPG User Manual iii

ESD precautions

Refer service to qualified personnel. Turn power off prior to

opening any of the consoles. Whenever doing work inside the

consoles use an ESD protective wrist strap.

Whenever a printed circuit board is put aside it must be put

into an ESD protective bag or on a grounded ESD mat.

Non-conductive items such as synthetic clothing, plastic

materials, etc. must be kept clear of the working area,

otherwise they may cause damage.

Printed circuit boards must be kept in ESD protective bags at

all times during storage and transport. The bags must only be

opened by qualified personnel using ESD protective

equipment as specified in this section.

Computer system

The simulator contains general purpose computers. Running

non Kongsberg Maritime software in any of them will void the

warranty. Connecting other keyboards, mice or monitors may

also void the warranty.

Notice

The information contained in this document is subject to

change without notice. Kongsberg Maritime shall not be liable

for errors contained herein or for incidental or consequential

damages in connection with the furnishing, performance, or

use of this document.

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iv Neptune CHS LPG User Manual

List of Abbreviations and Terms

AP Aft Peak

CBM Cubic Meter

CHS Cargo Handling Simulator

CT Center Tank

DO Diesel Oil

DS Dynamic Stability

DW Dead Weight

ECC Error Control Correction

FP Fore Peak

FS Free Surface

FWD Forward

Gb Giga byte

GM Gravity to Metacenter

OG Gas Oil

GZ Righting moment

HFO Heavy Fuel Oil

HMI Human-Machine Interface

Hz Hertz

IFE Institutt For Energiteknikk

IBC International Code for the Construction and the Equipment of

Ships Carrying Dangerous Chemicals in Bulk

IG Inert Gas

IMDGC International Maritime Dangerous Goods Code

IMO International Maritime Organisation

Kb Kilo byte

LAN Local Area Net

LCG Longitudinal Center of Gravity

LEL Lower Explosion Limit

LNG/C Liquefied Natural Gas Carrier

LOA Length Over All

LPG/C Liquefied Petroleum Gas Carrier

LPP Length between the Perpendiculars

MARPOL International Convention for the Prevention of Pollution from

Ships

Mb Mega byte

MEPC Marine Environment Protection Committee

MFLOPS Million floating point operations pr.sec.

MLC Meter Liquid Column

MIPS Million Instructions pr.sec.

MSC Marine Safety Committee

ODM Oil Discharge Monitor (equipment)

OTISS Operator Training Simulation System

P Port

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Neptune CHS LPG User Manual v

PC Product Carrier

PPM Parts Per Million

P/V Pressure/Vacuum

RAM Read Access Memory

S Starboard

SAST Special Analysis and Simulation Technology

SL.TK SLOP Tank

SOLAS International Convention for the Safety of Life at Sea

TC Tank Cleaning

UEL Upper Explosion Limit

UTC Universal Time Coordinated

VCG Vertical Center of Gravity

VLCC Very Large Crude oil Carrier

WS Work Station

WT Wing Tank

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vi Neptune CHS LPG User Manual

TABLE OF CONTENTS

Section Page

1 GENERAL .......................................................................... 1

2 SIMULATOR SYSTEM FUNCTIONS DESCRIPTION .......................... 1

2.1 Simulation philosophy ....................................................... 1

2.2 General training objectives ................................................ 2

2.3 Specific training objectives ................................................ 2

3 USER INTERFACE DESCRIPTION .............................................. 4

3.1 Physical layout ................................................................. 4

3.2 Computer system ............................................................. 6

3.3 Instructor station ............................................................. 6

3.4 Student workstation ......................................................... 6

3.5 Printer ............................................................................ 6

3.6 The functions of the major facilities .................................... 7

3.6.1 Computer system ............................................................. 7

3.6.2 Instructor workstation ....................................................... 7

3.7 Student workstation ......................................................... 8

3.7.1 Printer ............................................................................ 9

3.8 Installation and Keyboard Functions ................................... 9

3.9 To Install the Simulator ..................................................... 9

3.10 To Obtain a License Code ................................................ 10

3.11 To Select an Initial Condition ........................................... 11

3.12 To Start the Simulation ................................................... 12

3.13 Control Functions ........................................................... 12

3.14 Cargo Handling Simulators .............................................. 13

3.15 To Create an Initial Condition ........................................... 13

3.16 To End Simulation .......................................................... 13

3.17 Keyboard Commands ...................................................... 14

4 NEPTUNE INSTRUCTOR FUNCTIONALITY ................................. 15

4.1 Neptune Instructor Software Systems ............................... 15

5 VESSEL TO BE SIMULATED ................................................. 20

5.1 Vessel's Main Particulars ................................................. 20

5.2 Cargo Tanks .................................................................. 20

5.2.1 General Data ................................................................. 21

5.2.2 Tank capacities: ............................................................. 21

6 STUDENT PAGES ............................................................... 22

6.1.1 Picture Directory ............................................................ 22

6.1.2 Cargo Tank Overview ...................................................... 23

6.1.3 Ballast Tank Overview ..................................................... 24

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6.1.4 Bunker/Consumables ...................................................... 25

6.1.5 Shear Force ................................................................... 26

6.1.6 Bending Moment ............................................................ 27

6.1.7 Deflection ...................................................................... 28

6.1.8 Stability ........................................................................ 29

6.1.9 Shore Tanks .................................................................. 30

6.1.10 Ship/Shore Connection .................................................... 31

6.1.11 Load Discharge lines ....................................................... 32

6.1.12 Deck Lines ..................................................................... 33

6.1.13 Pen recorder .................................................................. 34

6.1.14 Cargo tanks ................................................................... 35

6.1.15 Hold Spaces ................................................................... 36

6.1.16 Compressor room ........................................................... 37

6.1.17 Re-liquefaction plant ....................................................... 38

6.1.18 Seawater cooling system 1 .............................................. 45

6.1.19 Seawater cooling system 2 .............................................. 46

6.1.20 Fresh water cooling system ............................................. 47

6.1.21 Inert gas system ............................................................ 48

6.1.22 Ballast system ............................................................... 49

6.1.23 High level alarms............................................................ 51

6.1.24 Gas detection system ...................................................... 52

6.1.25 CCTV CAMERA ............................................................... 53

6.1.26 Picture directory number 2 load master ............................. 55

6.1.27 Load master - Cargo Tank Overview ................................. 56

6.1.28 Load master - Ballast Tank Overview ................................ 57

6.1.29 Load master – Bunker and Consumables ........................... 58

6.1.30 Load master – Shear Forces ............................................ 59

6.1.31 Load master – Bending Moment ....................................... 60

6.1.32 Load master – Deflection ................................................. 61

6.1.33 Load master - Stability .................................................... 62

6.2 Help Systems ................................................................. 63

6.2.1 Unit conversion page ...................................................... 63

6.2.2 Message log ................................................................... 64

6.2.3 Symbol explanation page ................................................ 65

6.2.4 Help Menu ..................................................................... 66

7 OPERATION MANUAL ......................................................... 67

7.1 Description of the Gas Plant ............................................. 67

7.2 Regulations ................................................................... 67

7.3 List of Cargoes ............................................................... 68

7.4 Cargo Tank Data ............................................................ 69

7.5 Plant Design Data ........................................................... 69

7.6 Crossovers and Piping ..................................................... 69

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7.7 Utilities ......................................................................... 70

7.8 Survey of the Cargo System ............................................ 70

7.9 List of Abbreviations ....................................................... 72

8 PLANT CAPACITIES ........................................................... 73

8.1 Design Requirements ...................................................... 73

8.1.1 Loading ......................................................................... 73

8.1.2 Unloading ...................................................................... 73

8.1.3 Pressure Maintenance ..................................................... 73

8.2 Additional Capacity Information........................................ 73

8.2.1 Loading Rates for Loading with Cooling ............................. 73

8.2.2 Cooling-down of Cargo .................................................... 74

8.2.3 Pressure Maintenance ..................................................... 74

9 PLANT COMPONENTS AND SYSTEMS ...................................... 75

9.1 Cargo Systems ............................................................... 75

9.1.1 General ......................................................................... 75

9.1.2 Cargo Systems and Cargo Tanks ...................................... 75

9.1.3 Cargo System Combinations ............................................ 75

9.1.4 Cargo Systems and Crossovers ........................................ 75

9.1.5 Cargo Systems and Reliquefaction Plant Groups ................. 76

9.1.6 Cargo Systems and Booster Pumps ................................... 76

9.1.7 Cargo Systems, Cargo Heater and Cargo Cooler ................. 76

9.2 Cargo Tanks and Equipment ............................................ 77

9.2.1 Cargo Tanks .................................................................. 77

9.2.2 Process Connections and Internal Tank Piping .................... 77

9.2.3 Measuring and Control Equipment of Cargo Tanks .............. 77

9.3 Tank Safety Relief Valves ................................................ 78

9.4 Additional Pressure Relief System ..................................... 79

9.4.1 General ......................................................................... 79

9.4.2 Description and Function ................................................. 79

9.5 Tank Filling Limits........................................................... 80

9.5.1 Requirements by IMO ..................................................... 80

9.5.2 Filling Limits at Various Relief Set Pressures ...................... 80

9.5.3 Filling Limits by Warming-up the Cargo during the Sea Trip . 81

9.6 Deepwell Pumps ............................................................. 81

9.6.1 Description .................................................................... 81

9.6.2 Technical Data ............................................................... 81

9.6.3 Components .................................................................. 81

9.6.4 Operation and Maintenance of Deepwell Pumps .................. 82

9.6.5 Starting a Deepwell Pump ............................................... 82

9.7 Booster Pumps ............................................................... 83

9.7.1 Description .................................................................... 83

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9.7.2 Technical Data ............................................................... 83

9.7.3 Components .................................................................. 83

9.7.4 Duty of Booster Pumps ................................................... 83

9.7.5 Operation and Maintenance of the Booster Pump ................ 84

9.7.6 Starting Deepwell Pumps and Booster Pump in Series, without

Recycling during Start-up Phase ....................................... 84

9.7.7 Starting Deepwell Pumps and Booster Pumps, with Recycling

during Start-up Phase ..................................................... 85

9.7.8 Operating Booster Pumps in Series ................................... 85

9.8 Crossovers and Piping on Deck ......................................... 86

9.8.1 Each connection for liquid and vapour crossovers is fitted with:86

9.9 Reliquefaction Plant ........................................................ 87

9.9.1 Description of the Reliquefaction Plant .............................. 87

9.9.2 Duty of the Reliquefaction Plant ....................................... 88

9.9.3 The Reliquefaction Process .............................................. 88

9.9.4 The Reliquefaction Process as the Direct System ................ 89

9.9.5 The Reliquefaction Process as Combined System ................ 90

9.9.6 Components of the Reliquefaction Plant ............................. 91

9.10 Operation of the Reliquefaction Plant ................................ 97

9.10.1 Operation Data and Limits of Compressors ........................ 97

9.10.2 Operation of the Direct Cycle ........................................... 99

9.10.3 Operation of the Cascade Cycle ....................................... 101

9.10.4 Standstill Periods ........................................................... 102

9.10.5 Incondensable Gas in Ethylene - or LPG Condenser ........... 102

9.10.6 Operation of the R22 Cycle ............................................. 103

9.11 Operation of Cargo Compressor for Other Duties ............... 106

9.11.1 Other Duties ................................................................. 106

9.11.2 Starting the Cargo Compressor ....................................... 106

9.11.3 Vacuum Service ............................................................ 106

9.12 Combined Heat Exchanger (= CHE) ................................. 107

9.12.1 General ........................................................................ 107

9.12.2 Operating the CHE as an LPG Condenser .......................... 107

9.12.3 Operating the CHE as a Vaporizer .................................... 108

9.12.4 Operating the CHE as a Desuperheater ............................ 110

9.13 Cargo Heater, Cargo Cooler ............................................ 111

9.13.1 Cargo Heater ................................................................ 111

9.13.2 Cargo Cooler ................................................................. 112

9.14 Seawater Cooling System ............................................... 114

9.15 Freshwater Cooling System (= FW Cycle) ......................... 114

9.15.1 FW Cycle ...................................................................... 114

9.15.2 Starting the FW Cycle .................................................... 115

9.15.3 Stopping of Freshwater Cycle .......................................... 115

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9.15.4 Maintenance of Freshwater Cycle ..................................... 115

9.16 Vent and Drain System .................................................. 116

9.17 Blow-off System ............................................................ 116

9.18 Inert Gas Plant .............................................................. 117

9.19 Control Air System ........................................................ 118

9.20 Nitrogen System ........................................................... 119

9.21 Hydraulic System .......................................................... 120

9.22 Emergency Shutdown System (= E.S.D. System) .............. 121

9.23 Emergency Shutdown Valves (= E.S.D. Valves) ................. 122

9.24 Methanol Injection System ............................................. 123

9.24.1 Description ................................................................... 123

9.24.2 Injection of Methanol ..................................................... 123

9.24.3 Maintenance ................................................................. 123

9.25 Gas Detection System .................................................... 124

9.26 Hold Spaces .................................................................. 125

9.27 Emergency Shut-down System/E.S.D. System/Electrical Part126

10 PLANT PROCESSES AND OPERATIONS .................................. 127

10.1 Cleaning the Gas Plant ................................................... 127

10.2 Preparation of Hold Spaces ............................................. 128

10.2.1 Drying of Hold Spaces .................................................... 128

10.2.2 Topping of Cargo Holds .................................................. 128

10.3 Purging - General .......................................................... 129

10.3.1 General ........................................................................ 129

10.3.2 Alternatives for Drying and Inerting the Gas Plant ............. 130

10.3.3 Drying with Dry Air from the Inert Gas Plant ..................... 130

10.3.4 Purging with Inert Gas ................................................... 131

10.3.5 Purging with Cargo Gas generated on Board ..................... 131

10.3.6 Purging with Vapour of Refrigerated Cargoes from Shore .... 132

10.4 Checks before Admitting Cargo on Board .......................... 134

10.5 Cooling Tanks Down before Loading ................................. 135

10.5.1 Cooling-down of Cargo Tanks, with Gas-return to Shore, with or without Compressors ................................................. 136

10.5.2 Cooling-down of Cargo Tanks, with Liquid LPG from Shore,Gas

Reliquefied ................................................................... 136

10.5.3 Cooling-down of Tanks, with NH3 Gas from Shore, without

Gas-return .................................................................... 137

10.5.4 Cooling-down of Cargo Tanks, without Gas-return to Shore, for

Ethylene/Ethane Service (Start-up) ................................. 137

10.6 Loading of Tanks ........................................................... 138

10.6.1 General ........................................................................ 138

10.6.2 Loading with Gas-return ................................................. 139

10.6.3 Loading without Gas-return ............................................ 139

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10.6.4 Loading with Cooling ...................................................... 140

10.6.5 Loading with Heating-up, Gas-return to Shore .................. 140

10.7 Pressure Maintenance and Cooling at Sea ......................... 141

10.7.1 Reliquefaction - LPG/NH3 Service .................................... 141

10.7.2 Reliquefaction - Ethylene/Ethane Service .......................... 141

10.7.3 Indirect Cooling of Non-reliquefied Cargoes ...................... 141

10.7.4 Heating-up during Voyage .............................................. 141

10.8 Unloading ..................................................................... 142

10.8.1 General ........................................................................ 142

10.8.2 Unloading with DWPs and/or BPs without Vapour from Shore143

10.8.3 Emergency Unloading with BP, Gas transferred from Tank 2 to

Tank 1 ......................................................................... 143

10.8.4 Emergency Unloading with BP and CHE ............................ 143

10.8.5 Emergency Unloading with BPs in Series, Vapour from Shore143

10.8.6 Unloading with DWPs and BPs in Series and Heating-up

without Vapour from Shore ............................................. 144

10.9 Stripping of Cargo Tanks ................................................ 144

10.9.1 General ........................................................................ 144

10.9.2 Stripping of Cargo Tanks with vapour from Shore .............. 144

10.10 Draining the Crossover and Disconnecting the Shore

Connection ................................................................... 145

10.11 Heating-up of Tanks ...................................................... 145

10.11.1 General ........................................................................ 145

10.11.2 Heating-up of Tank ........................................................ 145

10.12 Evacuating of Tanks ....................................................... 146

10.13 Purging Vapour from Cargo Tanks ................................... 146

10.13.1 Purging with Inert Gas to LPG/VCM/Ethylene .................... 146

10.13.2 Purging with Dry Air to NH3 ............................................ 146

10.14 Aerating the Cargo Tanks (= filling of the tanks with air) .... 147

10.15 Aerating the Cargo Holds ................................................ 147

11 PLANT SEGREGATION AND SPOOL PIECES.............................. 148

11.1 One-grade Service ......................................................... 149

11.2 Two-grade Service ......................................................... 149

11.2.1 Setting of Spool Pieces ................................................... 149

12 ANNEX 1 .................................................................... 150

12.1 Instructor Pages ............................................................ 150

12.1.1 Operating Conditions ..................................................... 150

12.1.2 Initial Conditions ........................................................... 151

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Neptune CHS LPG User Manual 1

1 GENERAL This documentation is limited to describing and explaining relevant aspects governed by

the requirements in the Standard for certification of Maritime Simulator Systems. This

documentation is required together with the simulator in order to maintain the type

approval. This Document covers D 100, D200, D202 & D203 in the DNV Standard

2 SIMULATOR SYSTEM FUNCTIONS DESCRIPTION

2.1 Simulation philosophy

Over the past years simulator training has proved to be an effective method to train cargo

handling procedures, especially where an error of judgement can endanger life,

environment and property. A dynamic real-time computerised simulator can compress

years of experience into a few weeks, and provide knowledge of the dynamic and

interactive processes typical for real cargo operations.

Proper simulator training will reduce accidents and improve efficiency, and give the

trainees the necessary experience and confidence in their job-situation.

The best way to acquire practical experience is to learn from real life on real ship, but

today the efficiency requirements do not allow for this kind of onboard education, hence

the training can be carried out on a simulator. Practising decision making in a simulator

environment where decisions and their effects are monitored, opens a unique possibility to

evaluate these effects.

The opportunity to experiment on specific problems and get answers on questions such as:

"what happens if ....?" without leading to damaging of components and resultant off hire

costs, is unique. Simulation will give an easy introduction to background theories through

the realistic operation of the simulator.

It is important that the trainees experience life-like conditions on the simulator and that the

tasks they are asked to carry out are recognised as important and relevant in their job-

situation. The trainees shall be challenged at all levels of experience in order to achieve

further expertise and confidence.

Certain training objectives can only be reached properly by means of life-like hands-on

equipment and experience.

For some training objectives it is considered that colour-graphic workstation presentation

and practice will be sufficient. The choice will depend on the abstraction level the trainees

are able to cope with, their experience and the specifics of the training objective.

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2 Neptune CHS LPG User Manual

2.2 General training objectives

The Maritime Training Centre shall be able to train junior officers in basic cargo handling

operations, senior officers in emergency operations and trouble shooting, and to train

senior personnel in optimal operations during cargo handling. This will be achieved by

controlled training, leading to better understanding of the total cargo operation, as a

function of realistic simulation of a LPG carrier cargo system.

In order to fulfil these requirements the simulator shall be suitable for, but not limited to:

- basic and advanced training and education of students leading to professional

qualifications and a higher officer qualification;

- refresher and recurrent training for qualified officers;

- training officers in the operation of a LPG carrier's cargo equipment together with

the most vital auxiliary equipment;

- enabling detailed studies in the different processes of a ship's cargo system.

- training officers to localise faults and deterioration, and to clearly demonstrate the

impact of various types of faults and deterioration on the system's total efficiency;

- study of overall operational economy.

2.3 Specific training objectives

Dependent on background knowledge and experience of the trainee, the simulator shall at

least be capable of creating situations ensuring appropriate training in:

System familiarisation:

- tank arrangement

- pipe line arrangement

- pipe line control valves

- cargo compressors (high duty and low duty)

- pumps

- vaporizers

- instrumentation

- controls

- basic procedures

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Special operations and procedures:

- gas freeing

- gassing up

- tank atmosphere evaluation

- use of inert gas system

- use of nitrogen system and purging

- cool down of pipes and tanks

- draining and stripping

- forced vaporization and boil off to boiler

Cargo and ballast operations:

- general provisions

- ballasting

- de-ballasting

- loading cargo

- discharging cargo

Operational problems:

- normal working conditions

- introduction of

* system faults

* malfunctions

- emergency procedures.

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3 USER INTERFACE DESCRIPTION

3.1 Physical layout

The workstation-based Cargo Handling Simulator configuration can be as the following

arrangements in a network.

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Example of a room layout

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3.2 Computer system

All computers run on WINDOWS.

The instructor station will be the server

for all other computers.( On setup with a

lot of student stations we might have a

separate server) Together with the student

workstations it forms a complete

simulator computer system.

This concept is well proven and

extremely efficient for simulation

purposes. All new generations of cargo

handling simulators are based on this

concept.

Both the instructor- and the student

stations are based on the workstation.

3.3 Instructor station

The instructor station includes the following equipment:

- Computer

- Hard disk

- Monitor

- Operational keyboard

- Mouse

- Printer

The instructor has full access to the model.

3.4 Student workstation

The student workstation includes the following equipment:

- Computer

- Monitor

- Operational keyboard ()

- Mouse

- Printer

The student station has instructor controlled limitations to the model.

3.5 Printer

The printer is used as an alarm and event log.

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3.6 The functions of the major facilities

3.6.1 Computer system

The instructor workstation manages the software and use of peripherals, simulation

components and, allows real time simulations and recording, as well as exercise replay.

The real time simulation functions will provide the following:

- Operation of workstations.

- Operation of instructor station.

- Recording of:

- Simulation data

- Student action data

The simulating software is written in C language running under the WINDOWS operating

system.

The instructor workstation and the other simulator and computing units will be linked

using Ethernet, which is a Local Area Network (LAN). This LAN enables the computers to

share the disk systems using the Network File System (NFS) and a computing task may be

routed to any computer having spare capacity. Future extensions will easily be integrated

into the existing system because of the standardised LAN communication.

3.6.2 Instructor workstation

The instructor workstation and the student workstations are connected together in Ethernet

and are exactly of the same type. All workstations have an operational keyboard with

dedicated instructor function-keys. These function-keys can be accessed if, and only if, the

instructor switches the key lock to instructor mode. This facility is normally not used

during a training session with simulation of a total plant.

However, if the equipment is used for running several simulators, the instructor commands

must be handled from the various workstations. Due to this requirement, the operational

keyboard is specially designed for instructor commands and functions. The instructor

workstation will be the host computer and act as a server for all other computers. The

instructor functions are divided in two groups, the primary- and the secondary functions.

The primary functions are:

- Start of simulator

- Stop simulator

- Select scenario

- Run simulator

- Freeze simulator

The secondary functions are:

- Change scenario

- Alphanumeric pages of variables

- Alphanumeric pages of malfunctions

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- Alphanumeric pages of alarms

- Operating conditions

- Snapshots

- Replay

- Simulation speed (relative real time)

- Sound control

- Inhibit control of alarm systems

- Access control of input

The instructor has full control of the simulator and the training session through the above

listed functions. He can whenever he likes, change the environment during a scenario, and

evaluate the operators handling of the situation.

The printer acts as:

- Event log

- Alarm log

- Malfunction log

The instructor can select each of these logs. If more than one is selected, all the requested

events are printed out in chronological order.

3.7 Student workstation

The student workstation is provided as the central training device. The following

familiarisation, procedural training and experience will be possible:

- Familiarisation with piping and equipment layout

- Studies of process optimising and fuel economy

- Separately studies and tuning of control loops; temperature, level and pressure

- Familiarisation with the load calculator

- Preparation for port arrival/ departure

- Preparation dock set/ departure

- Preparation for loading and discharging

- Preparation for sea voyage

During each of these conditions, a number of systems must be tuned to function properly.

Economic and safe operation of the ship is based on reliable equipment and skilled officers

who can take correct decisions at the right time. These simulations are partly made

possible by a well developed man-machine interface.

The system design facilities in the KONGSBERG MARITIME CARGO HANDLING

SIMULATOR concept, has taken all these factors into consideration during design and

engineering. The result is a comprehensive system that allows the students to work under

conditions close to real ship environment.

The student workstation may be run in the full simulation or part task simulation mode:

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- In full simulation mode the workstation reflects the behaviour of the total current

simulator scenario for the student to observe and to influence or change.

- When operated in part task mode the student has full control of the simulation

program and scenario he has selected to run, completely independent of the simulator

itself.

3.7.1 Printer

The printer acts as:

- Event log

- Alarm log

- Malfunction log (only accessible by instructor)

Each of these logs can be selected by the student/instructor. If more than one is selected, all

the requested events are printed in chronological order.

3.8 Installation and Keyboard Functions

Step by step procedure to install and operate Kongsberg full-scale Cargo simulators. The

following instructions apply to all our cargo handling simulators.

3.9 To Install the Simulator

The program can be installed on any PC running Windows NT, Windows 2000 or

Windows XP. Minimum requirements are 450 MHz PIII with 128 Mb RAM. Do the

following:

1. Start Windows, if necessary.

2. Insert the CD-ROM into the drive.

3. If the program does not auto start, start Windows Explorer.

4. Double-click the Setup.exe file.

5. Follow the on screen instructions.

6. When prompted specify the Typical installation option.

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3.10 To Obtain a License Code

Before you can use the simulator you need a license code. Do the following:

1. Double-click the program icon placed on your desktop.

2. Send an e-mail to [email protected] including the specified hardware code

and your name.

3. When you receive the license code double-clicks the program icon.

4. Copy in the license code exactly as it appears.

5. Push OK.

6. The installation is now complete and the simulator is ready for use.

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3.11 To Select an Initial Condition

The cargo system can be started at different operating conditions dependent on the training

objectives.

1. If not already running, double-click the simulator program icon to start the program or

push Home.

2. The Picture Directory window appears.

3. Click once inside the Picture Directory window.

4. Push F5 to display the Operating Conditions window.

5. Push the Initial Conditions button.

6. Select one of the available conditions by clicking on it.

7. The condition is loaded and the simulator is ready for training.

Note: Initial conditions can only be changed while the simulator is in freeze.

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3.12 To Start the Simulation

When the simulator is started conditions are frozen.

1. Push F1 to start the simulation.

2. Running is displayed in the upper left corner.

3. Push Home to display the Picture Directory.

4. Push any picture name to display the corresponding process diagram.

3.13 Control Functions

The simulator allows you to control pumps, valves, and controllers etc. as follows:

• Pumps: Click to start, right-click to stop.

• Valves: Click to open, right-click to close.

• Controllers: Click to access control functions. Enter values as required. The cursor

changes where control functions are available.

• Sound: Push F5 to access Operating Condition, and push Sound System. For engine

room simulators only! Requires PC fitted with speakers.

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3.14 Cargo Handling Simulators

In the Picture Directory the picture number background is colour coded as follows:

• Green: Indicates processes taking place in the tank system.

• Beige: Indicates control panels, ship views and various printed diagrams.

3.15 To Create an Initial Condition

The simulation can at any time be stopped and the current situation saved for later use.

1. To freeze the simulation push F2.

2. Push F5 to display the Operating Conditions window.

3. Push the Initial Conditions button.

4. Push the Create button, select an unused button and type in a name for the new

condition.

5. Push Enter.

3.16 To End Simulation

To end the simulation and stop the simulation program do the following:

1. To end the simulation push F3.

2. Type Y and push Enter.

3. The system exits the simulation program.

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3.17 Keyboard Commands

The following contains a list of keyboard commands to control and monitor the simulation.

F1 Run simulation

F2 Freeze simulation

F3 Stop, end simulation

F4 Snapshot

F5 Operating condition

F6 Scenario

F7 Recall picture

F8 Alarm log

F9 Malfunction page directory

F10 Variable page directory

F11 Alarm page directory

F12 Alarm silence

Home Picture directory

Page Down Next picture

Page Up Previous picture

Shift + F4 Replay/Snapshot dir.

Shift + F6 Initial condition

Shift + F7 Mark picture

Shift + F8 Alarm log acknowledge

Alt + F12 Toggle window decorations

Shift + Home Picture number (mdxx)

Ctrl + P The current display is printed on the colour printer.

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4 NEPTUNE INSTRUCTOR FUNCTIONALITY Kongsberg Maritime simulators have released for the Engine Room and Cargo Handling

Simulators the “State of the Art” Instructor, Monitoring and Assessment system.

Kongsberg in close cooperation with experienced world wide instructors, Norwegian

Maritime Directorate and Det Norske Veritas (DNV), have designed and developed an

Instructor, Monitoring and Assessment System that is excellent with regards to user-

friendliness and efficiency.

This chapter list available features that can be delivered along with this simulator.

4.1 Neptune Instructor Software Systems

The following will be provided:

Item Content Neptune

Instructorless

Neptune Instructorless gives instructor and students the option to

run readymade exercises, where following features are included.

Includes:

All configurations includes well proven models

Load simulation model on each station

Run simulation

Freeze simulation

Stop simulation

Load initial conditions

Create new initial conditions

Students can run the simulation independently

Insertion of malfunctions

Access to alarm list

Access to variable list.

Neptune Basic Includes:

Neptune Instructorless; as previously listed

Power-up all student stations

Recording of the complete exercise

Replay the whole exercises

Go back to any point in time for restart

-Create exercises including Initial conditions

Deploy exercises to student stations

-Centralized Run/Freeze control of all student stations

Connect student stations in clusters for team training

Send Instant Messages to student(s)

Send Instant Actions (Malfunctions or Events)

Recording of the complete exercise

Power shut-down of student stations

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Item Content Neptune

Professional

Includes:

Neptune Basic; as previously listed

Student Station (Access) Configuration

Exercise development, incl. triggers and actions

E-Coach, Electronic guidance system to students

Assessment

Item Description Instructor

Station

Classroom

View

Monitor and control the

students in the classroom (or

full mission simulator).

Instructor can tailor the view

according to site layout

Instructor

Station

Classroom

View

-Start exercises on PC’s in the

classroom

-Run/pause exercises in the

classroom

-“Client Connect” to exercises

in the classroom

-Set up groups for team

training

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Item Description New Exercise

Structure

Exercise Structure comprises:

Initial Condition and

Scenario Modules

based on:

Triggers

E-Coach Messages

Actions

Assessment

Instructor

Controlled

configuration

for each of

the Student

Stations

Configuration of stations is

part of the exercise. It is

possible to add new stations to

an ongoing exercise “on the

fly”.

Trigger

Overview

Displays the state (Active/Not

Active) of all the triggers in

the module.

Displays users of the trigger

(other triggers, actions,

assessment and e-coach

messages)

Link to editors

Instructor control of triggers

(on the fly).

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Item Description Logic Block

Based Trigger

Editor

Building block used in e-coach

messages, actions and

assessments

Graphical editor

Flexible and powerful

Calculates output

(true/false) based on input

and logic blocks.

Configurable input

E-Coach

Overview

Displays the state (sent/ not

sent) of all e-coach messages

Link to trigger and

message editor

Possible for the instructor

to disable messages

(online).

E-Coach

Editor

Initiated by trigger

From “virtual instructor”

or other “outside world”

(e.g. Captain, VTS)

To a selected screen or all

screens.

Action and

Malfunction

Editor

Activated by trigger:

Additional triggers to

specify on/off conditions

for the criterion

Possible to select between

different types of scoring

(illustrated graphically)

Possible to define “critical”

criteria Action and

Malfunction

Editor

Malfunction introduced as

on/off. Instructor can freely

decide when and for how long

the malfunction shall be

activated

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Item Description Action and

Malfunction

Editor

Malfunction introduced as

repeating on/ off.

Action and

Malfunction

Editor

Malfunction introduced as a

repeating sine shape, where

Amplitude and Time period is

adjustable.

Action and

Malfunction

Editor

Malfunction introduced where

intensity and duration is

randomly selected.

Assessment

Overview

Overview of all assessment

criteria

Calculates total score

Instructor can define

parameters for overall

scoring

Pass and Fail evaluation is

completely based on

objective criteria

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5 VESSEL TO BE SIMULATED

5.1 Vessel's Main Particulars

Length overall 126,20 m

Length between perpendiculars 122,02 m

Breadth moulded 17,80 m

Depth moulded main deck 11,90 m

Draught on summer freeboard 8,60 m

Speed (designed full loaded cond.) 15,5 Knots

Deadweight 9470 MT

Gross tonnage (Int.) 7095 GT

Class Det Norske Veritas, 1A1, Tanker for Liquefied

Gas, (dat -104 C) Ice-C, E0 MV.

5.2 Cargo Tanks

The cargo containment system is of the independent IMO type C. The tanks are of bilobe

construction, divided by a closed longitudinal bulkhead into two tank halves connected by

a balance line in the vapour face.

The cargo tanks are designed to carry all liquefied petroleum gases (LPG), Ammonia and

Ethylene with a minimum temperature of - 104oC and a maximum tank pressure of 4,5 bar

g. Some noxious liquid substances may also be carried.

The cargo tanks are also designed for a permissible vacuum of 0,5 bar abs.

Maximum allowable density is 970 kg/m3.

The cargo tank is fitted with a central pipe tower. The tower supports and contains the

cargo pumps, discharge and filling lines, Whessoe float gauge system, Purge lines, spray

lines and gas sampling pipe. Access to the tank is via a manhole fitted on the dome top.

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5.2.1 General Data

Item Data

Number 3

Shape bilobe

Type Independent C

Max. perm. filling 98%

Max. pressure 5,5 bars abs

Valve setting – min. 1,0 bars abs

- max. or IMO 5,5 bars abs

- max. USCG tank 1 - 4,17 bars abs

tank 2 - 4,21 bars abs

tank 3 - 4,21 bars abs

Max perm. vacuum 0,5 bars abs

Min perm. temperature -104oC

Max. perm. specific gravity 970 kg/m3

Cargo tank material Mild steel/ nickel cadmium

Type of cargo tank insulation Polyurethane

5.2.2 Tank capacities:

Tanks Frame Capacity m3

No 1 Port 125 -163 1182,2

No 1 Starboard 125 -163 1182,18

No 2 Port 86 - 122 1468,07

No 2 Starboard 86 - 122 1469,26

No 3 Port 47 - 83 1468,57

No 3 Starboard 47 - 83 1468,18

Total cargo capacity 8238,46

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6 STUDENT PAGES

6.1.1 Picture Directory

The Picture Directory will give the operator an overview of all process pictures. From this

directory any picture can be selected by clicking on the name field of the picture.

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6.1.2 Cargo Tank Overview

The Cargo Tank Overview will give the operator a total view of the cargo tanks with

information about the cargo and tank level, shown as a bar graph, as well as vital data of

the ship’s condition like trim, list, deadweight, stability and draught. The small picture of

the ship at the bottom of the page makes it possible to quickly change the picture to either

one of the cargo tanks, or holds by just clicking at the corresponding area of the small ship.

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6.1.3 Ballast Tank Overview

The Ballast Tank Overview picture will give an overview of all the ballast tanks with

information about the volume in the tanks shown as a bar graph. Ship conditions will be

dynamically updated based on tank ullage.

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6.1.4 Bunker/Consumables

The Bunker/Consumables Picture gives an overview of all tanks not related to cargo

operations like HFO, DO, FW and forepeak/aft peak tanks.

The picture displays both a layout of the tanks as well as an ullage bar graph shown in %.

These tanks can be manually filled or emptied in this picture.

A summary of the tanks will also be shown.

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6.1.5 Shear Force

The Shear Forces are calculated from the load distribution of the ship including the steel

weights of the different hull sections, and the corresponding buoyancy forms.

The graphic picture will display three different curves: yellow shows maximum permitted

shear forces in harbour condition; red curve the maximum permitted shear forces in

seagoing condition and the blue curve is the actual shear forces.

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6.1.6 Bending Moment

The Bending Moments are calculated from the Shear Forces. The actual bending moment

curve is drawn in blue; the yellow and red curves give maximum limits for respectively

harbour and seagoing condition.

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6.1.7 Deflection

The hull’s deflection (from the straight line) is calculated from the bending moments and

from the elasticity of each hull section. Positive deflection represents a hogging hull

condition; negative deflection represents a sagging hull condition.

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6.1.8 Stability

The stability curve in the form of righting arm values is calculated for heel angles ranging

from 0 to 60 degrees. All righting arm values are corrected (reduced) for possible "free

surface" effects. The reduction in meta centric height is specifically given.

The area under the stability curve represents the heel resistance or dynamic stability.

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6.1.9 Shore Tanks

The Shore Tanks picture gives an overview of the shore tank which we can load from or

discharge to. Note also the Emergency Shutdown Button in the lower right corner.

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6.1.10 Ship/Shore Connection

Ship/Shore connection shows the shore and the vessel manifold. Shore has two liquid

manifolds and two vapour manifolds. It also indicates a lightering barge/vessel can be

used.

The manifold all the way to the left in the picture is the discharge manifold on the vessel

and the ballast receiving manifold on the shore side.

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6.1.11 Load Discharge lines

The ship is designed as a TWO-GRADE VESSEL. This means that the vessel can

simultaneously load, transport and unload two different cargoes.

There are 2 sets of crossovers, each set with one liquid crossover and one gas crossover.

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6.1.12 Deck Lines

The cargo tanks and the gas plant are designed in such a way that alternatively one or two

separate cargo systems can be arranged.

Each cargo system comprises cargo tank(s), liquid crossover and gas crossover,

alternatively, also a reliquefaction system, booster pump(s) and the cargo heater.

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6.1.13 Pen recorder

With the pen recorder it is possible to log any tag value that may be required. It is possible

to monitor 6 channels at the same time.

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6.1.14 Cargo tanks

There are three cargo tanks. Each tank is provided with 2 deepwell pumps and connections

for cargo and purging.

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6.1.15 Hold Spaces

Around the cargo tanks there are hold spaces, from this page monitoring and control of the

hold spaces can be executed.

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6.1.16 Compressor room

The reliquefaction plant comprises 3 cargo compressors, 3 liquid separators, 2

seawater-cooled or heated combined heat exchangers, respectively, 2 R22-cooled ethylene

condensers, 2 flash drums, 2 cargo receivers, and 2 complete R22 refrigeration units with

screw compressors, R22 condensers and economizers. The combined heat exchangers can

be used as LPG condensers, vaporizers or gas coolers.

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6.1.17 Re-liquefaction plant

The re-liquefaction plant can be connected to one cargo system.

Alternatively, the reliquefaction plant can be split into two independent reliquefaction

groups, each reliquefaction group being connected to another cargo system.

Each re-liquefaction group consists of the following main components:

- one cargo compressor with surge drum - one flash drum - one LPG

condenser/vaporizer/desuperheater - one ethylene condenser - one cargo receiver

Cargo Compressor 1

The compressor in the compressor room is connected to its electric motor in the adjacent

E-room by an intermediate shaft with a gas tight bulkhead penetration. The bulkhead

penetration is provided with a mechanical seal, which is oil-lubricated and cooled by an

external glycol water circuit. A temperature switch stops the motor, if the oil temperature

rises to high.

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Cargo Compressor 2

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Cargo Compressor 3

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Heat exchanger 1

The heat exchanger is designed to decrease the superheat of hot gas before condensed with

R22 circuit, to condensate cargoes of the DIRECT CYCLE and to vaporise several cargoes

by seawater.

The heat exchanger is a shell and tube heat exchanger, seawater flows in tubes.

For condensing, the heat exchanger is fitted with an HR valve to vent incondensable gases

(Nitrogen).

For vaporising of cargo, the heat exchanger is fitted with a pressure control valve and level

control valve to avoid freezing or overfilling, respectively.

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Heat exchanger

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R22 Compressor 1

The R22 compressors are used together with the cargo compressors in a cascade cooling

circuit for colder cargoes like ethylene, or when the differential pressure between 1st stage

suction and condenser pressure be too high.

The R22 condenser is a shell and tube heat exchanger with receiver. R22 is condensed on

shell side by warming up of seawater in the tubes. The condenser is fitted with a pressure

indicator on shell side and a temperature indicator for seawater outlet temperature. The

combination R22 receiver/condenser is designed to accumulate the whole charge R22 of

the circuit. It is fitted with a temperature indicator and level indicator.

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R22 Compressor 2

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6.1.18 Seawater cooling system 1

Seawater pumps (3 x 350 M3 A) supply seawater to the heat exchangers of the gas plant.

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6.1.19 Seawater cooling system 2

One seawater pump (115 M3 A) supplies for inert gas plant.

Seawater pump (1 x 25 M3 A) supplies seawater to the freshwater cooler.

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6.1.20 Fresh water cooling system

A pump circulates freshwater through the compressors for cooling/ heating of the cargo

compressors, heating the oil in oil separators of the R22 cycles and to the bulkhead

penetrations for cooling. The cycle is also operated when the compressors are stopped and

kept ready for service. This decreases condensation of vapours in compressor cylinders

(liquid slugs) and in compressor crankcase (oil failure) as well as condensation of R22 in

oil separator. The temperature of the freshwater is automatically maintained constant.

The main components of this system are:

- 2 circulating pumps 25 M3 A, at 35 m LC

one pump as standby

with electric motors 4.6 kW, 3500 rpm

- 1 electric freshwater heater 24 kW

- 1 freshwater cooler, cooled by seawater

tube bundle length 1200 mm

shell outer diameter 273 mm

- 1 freshwater tank, with level glass and l

low level alarm

- controls for flow, temperature and pressure

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6.1.21 Inert gas system

The cargo handling simulator is modelled with an inert gas plant where gas oil is burned

effectively and directed through the scrubber to the main inert gas deck line. The capacity

of the inert gas plant is approximately 2800 m3/h. The scrubber washes and cools the flue

gas in order to reduce soot and SO2 content.

The inert gas plant is fitted with two air inlets, one for each fan, allowing the plant to take

air instead of inert gas for ventilating and gas-freeing cargo tanks.

The drier unit consists of two units: the refrigerating/cooling unit and a drier unit

containing activated alumina. They are in this model fully automated.

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6.1.22 Ballast system

All ballast tanks are connected to a ring main piping system via one suction/filling line.

The ballast tanks are used to maintain the vessel at a safe draught, trim and stability

throughout all cargo operations and transport.

Ballast Distribution

All ballast tanks are situated in the double bottom. They give a graphic view of the content

of the different tanks as well as the sounding. All connections between the tanks with lines

and valves are shown. In addition we are also given the trim, list and draft measurements.

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Ballast pump room

The ballast pump room picture shows a schematic view of the actual ballast pump room. In

this room there are three ballast pumps and an ejector.

These ballast pumps have a capacity of 300 m3/h – 35 mTH (SW).

The ejector has a capacity of 300 m3/h – 20 mTH (SW).

From here there is also a connection to the ballast deck manifold, which can be used if

ballast should be pumped ashore.

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6.1.23 High level alarms

Each tank half is equipped with:

1 level indicator, full range, with local and remote indication, with high level switch

at 99% of tank volume and adjustable high level alarm and low level switch.

1 high level switch at 99% with pre-alarm at 95% of tank level

The 99% high level switches close all ESD valves of this tank and stop all running pumps.

4 sample tubes with ball valves, for gas sampling at tank 0/50%/99% level and in

pump sump.

3 temperature elements on tank outside, for remote indication of temperature at tank

sump and tank wall temperatures at different heights.

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6.1.24 Gas detection system

With the gas detection system we can measure %LEL at various places onboard. The point

to be measured can either be choosen manually or the system can be set to check at each

measuring point in an automatic sequence

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6.1.25 CCTV CAMERA

Via the MD page nr 140 you can get up the picture from the CCTV Camera.

You can see either the vessels manifolds or the vessel seen from the dock.

This can be chosen from buttons in the picture.

This is visualizing the connection/disconnection of loading arm or cargo hoses.

If you should get a leakage in the manifold connection or blind flange this will also be

visible. Leakages can be triggered either from wrong procedure during disconnection or

from a malfunction set by the instructor.

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From the operation page which is accessed via the “F5” button it is possible to change the

operating scenario. “Weather scenario” and “Ship state” can be changed

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6.1.26 Picture directory number 2 load master

The purpose of the Data Load load/stress calculator is to avoid excessive bending stresses

in the hull structure by offering the stress calculations off-line in advance. These stresses

vary with the cargo distribution throughout the length of the ship. Incorrect loading can

damage the ship and hence the cargo/ballast must be placed according to a carefully

calculated plan. Standard plans are often prepared by the shipyard.

However, it is impossible to foresee all cargo distributions, it is therefore necessary to have

a sophisticated calculator on board which can provide all the appropriate stresses for every

load distribution case which is manually input.

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6.1.27 Load master - Cargo Tank Overview

From this picture it is possible to try out various tank settings, and it does not matter

whether you put in the sounding, the volume (in %) or the mass of the cargo. The Data

Load load/stress calculator will do the right calculation anyway. The corresponding trim

and list will change accordingly.

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6.1.28 Load master - Ballast Tank Overview

Here you enter the different values of the ballast tanks shown as bar graphs.

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6.1.29 Load master – Bunker and Consumables

All consumables may be entered here in a simple way, and the trim and list will change

accordingly. This makes it easy to try out and plan a stowage for a trip.

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6.1.30 Load master – Shear Forces

This picture shows the actual shear forces which will affect the ship in this situation. This

makes it possible to check if the wanted condition is suitable for the ship or not.

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6.1.31 Load master – Bending Moment

This picture shows the actual bending moments which will affect the ship in this situation.

This makes it possible to check if the wanted condition is suitable for the ship or not.

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6.1.32 Load master – Deflection

This picture shows the actual deflection which will affect the ship in this situation. This

makes it possible to check if the wanted condition is suitable for the ship or not.

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6.1.33 Load master - Stability

This picture shows the actual stability of the ship in this situation. This makes it possible to

check if the wanted condition is suitable for the ship or not.

Damage Stability

To check the vessels damage stability it is possible to simulate how the stability will

become if you get water ingress into the engine room or into hold spaces. This can be seen

at the off line load calculator.

In the Variable page Directory you can find a line called “Damage Stability”.

From here you can choose which compartment there is damage to. If the damage is in the

engine room, you can set the amount of water inside.

If the damage is in the ballast tanks the water level in the damaged tank will be decided

by the actual loading condition you have in the Load Calculator

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6.2 Help Systems

The system contains the following help related functionalities:

-Unit Conversion Page.

-Operator messages (i.e. no access, value to high etc.)

-Symbol explanation page

- Help menu accessed through upper right corner on each screen

6.2.1 Unit conversion page

The unit conversion page can be loaded and accessed from the bottom left toolbar on each

screen. All relevant units can be converted by inserting the value in the appropriate

column.

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6.2.2 Message log

A message log sorts and reports all actions sorted by

Manual actions

Automatic actions

Malfunction log

Alarm log

Instructor actions

The Icon for opening the message log can be found on the lower left corner on each screen.

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6.2.3 Symbol explanation page

A separate screen called description of legends explains all symbols and colour codes used

in the simulator.

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6.2.4 Help Menu

The simulator contains an easy accessible help menu based on WinHelp 2000© from

RoboHelp. This is also referred to as the quick reference manual where basic help for

operating the menus and computer system can be obtained.

Kongsberg Maritime

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7 OPERATION MANUAL This section of the document is intended for regular use at the simulator centre and

provides information applicable to operate the simulated gas carrier. This manual is based

on a real ship manual, so certain functions is simplified or left out in the simulator.

7.1 Description of the Gas Plant

The gas plant and the cargo tanks of this gas carrier are designed for the transport of

liquefied gases (cargo) as specified, i.e.

to load simultaneously two grades of fully or semi-refrigerated cargoes with or

without gas return line from shore

to carry two grades of cargoes under fully or semi-refrigerated conditions

to unload two grades of cargoes to shore with deepwell pumps with or without gas

return line, and, if required, by booster pumps, additionally

to carry out the preparatory operations, such as purging with inert gas, dry air or

cargo gas, cooling of tanks and of the systems, gasfreeing and ventilation of tanks

with inert gas or dry air, etc. in accordance with relevant codes and recommendations

The gas plant comprises components for loading, unloading and gasfreeing of the cargo

tanks, for reliquefaction of the boil-off or for cooling of cargo.

This Operation Manual describes the gas plant, its design data, components and systems

and gives instructions on operation and maintenance. Furthermore, the manual describes

main processes and process steps for various plant operations and loading cases.

The plant is to be operated within the limits of plant design and in accordance with the

instructions given in this manual.

7.2 Regulations

The real gas plant is built in compliance with the rules and regulations of:

Code for the construction and equipment of ships carrying liquefied gases in bulk ( IGC

Resolution MSC5 (48)) Type IIG ship of International Maritime Organization (IMO)

approved by

Det Norske Veritas (DNV) Certificates for the equipment

Local Administration (NMD) Certificate of fitness

United States Coast Guard (USCG) Letter of compliance for foreign

ships (yard's assistance)

Registro Italiano Navale (RINa) Consideration of the rules of

The construction supervision and acceptance by DNV, MARPOL Annex II: Equivalency

for Gas Carriers (Reg. 2 (5)).

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7.3 List of Cargoes

The cargo system is designed for the transport of following cargoes:

Cargo names in BOLD letters is included in the Simulator, the Simulator also have a few

other cargoes.

UN-No. Cargo Formula Remarks

1005 Anhydrous Ammonia NH3 Refrigerated

1010 Butadiene CH2CHCHCH2 "

1011 Butane C4H10/CH(CH3)3 "

1011/1978 Butane-Propane Mixtures - "

1012 Butylene CH3CH2CH:CH2

or CH2:C(CH3)2

1037 Ethyl Chloride C2H5Cl

1038 Ethylene C2H4 "

1063 Methyl Chloride CH3Cl "

1077 Propylene CH3CH:CH2 "

1086 Vinyl Chloride (VCM) CH2:CHCl "

1961 Ethane C2H6 "

1978 Propane1) C3 H8 ".

- C4/CS Stream2) -

1032 Dimethylamine (CH3)2NH Non-refriger.

1036 Monoethylamine C2H5NH2 "

1089 Acetaldehyde CH3CHO "

1155 Diethyl Ether C2H5OC2H5 "

1218 Isoprene CH2:CHC(CH3):CH2 "

1221 Isopropylamine (CH3)2CHNH2 "

1280 Propylene Oxide P.O. CH3CHCH2O "

1302 Vinyl Ethyl Ether CH2CHOCH2CH3 "

2983 EO/PO (30/70) C2H4O/CH3CHCH2O "

1. The maximum content of ethane in commercial propane is 2,5 mol%, referred to

liquid product at 1 bar abs.

2. With a saturation pressure of 1.8 bar g at 37.8 °C

Min. density: 0.50 kg/dm3

Max. density: 0.97 kg/dm3

It is also possible to carry other products which are not mentioned in the above list,

provided they are covered by the regulations of Para 1.2 and their characteristics are within

the limits of the plant design. The ship can transport 2 different cargoes simultaneously.

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7.4 Cargo Tank Data

There are 3 cargo tanks of the Independent Tank Type C.

Geometric volumes are approximately (at 100%, including dome):

Tank No. 1 2,330 m3

Tank No. 2 2;940 m3

Tank No. 3 2,940 m3

Total volume 8,210 m3

Design Data

Maximum cargo density 0.99 t/m3

Maximum relief valve set pressure

4.5 bar g = MARVS according to IMO

3.2 bar g = MARVS according to USCG

0.5 bar g = Minimum Working Pressure of APRS

Minimum tank pressure (vacuum) 0.5 bar a

Minimum transport temperature -104 °C

Maximum transport temperature +45 °C

Average k-value of insulation < 0.16 kcal/m2 hºC

7.5 Plant Design Data

Maximum ambient temperature (air) +45 °C

Design temperature for electric motors (air) +50 °C

Maximum seawater temperature +32 °C

Loading time approx. 10 h

Unloading time, with deepwell pumps approx. 8 - 10 h

Unloading time, with booster pumps,

operating in parallel approx. 14 h

For additional capacity data, see Section 2.

7.6 Crossovers and Piping

Sequence of crossovers, from fore to aft

Crossover I liquid - vapour

Crossover II vapour - liquid

Crossover connections, both starboard and portside

Presentation flanges of liquid crossover I 8" ANSI 300 RF

crossover II 8" ANSI 300 RF

Presentation flanges of vapour crossover I 4" ANSI 300 RF

crossover II 4" ANSI 300 RF

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Two separated piping systems are provided. Any tank can be connected

to any system.

Design Pressures

Loading and unloading lines 25 bar g

Manifold and unloading lines after booster

pumps 25 bar g

Design Temperatures

Lines from compressor 2nd stage to condensers + 150 °C

All other lines + 70 °C

7.7 Utilities

Electrical power supply 3 x 440 V, 60 cycles

Compressed air supply min. 5.5 bar g

Inert gas supply 0,3 bar g

Seawater supply

- for reliquefaction plant and/or cargo heater 3 x 350 M3 /h, 3 bar g

- for inert gas plant 1 x 115 m3/h, 4 bar g

- for freshwater cooler 1 x 25 M3 /h, 3 bar g

7.8 Survey of the Cargo System

The ship is designed as a TWO - GRADE VESSEL. This means that the vessel can

simultaneously load, transport and unload two different cargoes.

The cargo tanks and the gas plant are designed in such a way that alternatively one or two

separate cargo systems can be arranged.

Each cargo system comprises cargo tank(s), liquid crossover and gas crossover,

alternatively, also a reliquefaction system, booster pump(s) and the cargo heater.

There are three cargo tanks. Each tank is provided with 2 deepwell pumps and connections

for cargo and purging.

There are 2 sets of crossovers, each set with one liquid crossover and one gas crossover.

The deck house contains all cargo machinery, except inert gas plant, booster pumps and the

cargo heater.

The deck house is divided into gas machine room and electric room. The cargo control

room is located inside the superstructure. All rooms are on main deck level.

The reliquefaction plant and its auxiliary equipment is located in the gas machine room.

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The reliquefaction plant comprises 3 cargo compressors, 3 liquid separators, 2

seawater-cooled or heated combined heat exchangers, respectively, 2 R22-cooled ethylene

condensers, 2 flash drums, 2 cargo receivers, and 2 complete R22 refrigeration units with

screw compressors, R22 condensers and economizers. The combined heat exchangers can

be used as LPG condensers, vaporizers or gas coolers.

The reliquefaction plant can be arranged into two independent reliquefaction systems, each

able to handle one cargo system with cooled cargo.

The electric motors for the cargo and R22 compressors, the motor control center,

equipment for the glycol water cycle and solenoid valves for hydraulically actuated

quick-closing valves are located in the electric room, adjacent to the gas machine room.

The cargo control room is provided for monitoring of the gas plant.

Two booster pumps, mounted on deck, can be used to increase the discharge pressure when

unloading, or in case of emergency unloading (deepwell pump failure) as discharge pumps.

There is a cargo heater, mounted on deck. This heat exchanger can be connected to each

cargo system.

An inert gas plant, installed below deck, supplies inert gas or dry air for purging and

inerting of hold spaces, cargo tanks and gas plant. (Inerting of hold spaces is not required

normally.)

There are 3 vent masts, located on the main deck between tanks 1 and 2. Each tank is

connected to one of these masts.

Before loading the following cargoes, flame screens should be provided on outlets of vent

masts:

- diethyl ether

- ethylene oxide

- propylene oxide mixture

- isoprene

- propylene oxide

- vinyl ethyl ether

- monoethylamine

- isopropylamine

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7.9 List of Abbreviations

The following abbreviations have been used in this description:

Para - Paragraph

dwg. - Drawing

P + I - Piping and Instrument Diagram

M & R - Measuring and Control Equipment

PS - Portside

SB - Starboard

GMR - Gas Machine Room

E-Room - Electric Motor Room

MCC - Motor Control Center

CCR - Cargo Control Room

CCC - Cargo Control Console

CCB - Cargo Control Board

CO - Crossover .

IG - Inert Gas

N2 - Nitrogen

SW - Seawater

GW - Glycol Water

DWP - Deepwell Pump

BP - Booster Pump

HR Valve - Hand-regulating Valve

E.S.D. - Emergency Shut-down

MARVS - Maximum Allowable Relief Valve Setting

of a Cargo Tank

CHE - Combined Heat Exchanger

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8 PLANT CAPACITIES

8.1 Design Requirements

8.1.1 Loading

The ship can be loaded in 10 hours, with or without vapour return to shore. A loading time

of 10 hours corresponds to an average loading rate of approx. 820 m3/h. If the cargo has to

be cooled during loading, the loading rate is lower.

8.1.2 Unloading

The ship can unload in 8 - 10 hours, with or without vapour return to shore. When

unloading with deepwell pumps and booster pumps, the unloading time is approx. 14 h.

8.1.3 Pressure Maintenance

For one or two-grade service, one or two cargo compressors and one R22 compressor are

available to handle the boil-off during pressure maintenance.

The remaining compressors are in spare.

8.2 Additional Capacity Information

This section gives additional information on capacities and process times required:

8.2.1 Loading rates for loading with cooling

8.2.2 Cooling-down of cargo

8.2.3 Pressure maintenance

Because of many factors of influence (such as cargo, seawater and ambient temperatures,

fouling of the heat exchangers, non-condensable gases and number of process alternatives),

this information cannot cover all circumstances.

Calculations are necessarily based on certain assumptions and simplifications. Therefore,

the data given must be considered only as a guide.

8.2.1 Loading Rates for Loading with Cooling

The following diagrams show the maximum loading rates when loading liquid with a

saturation pressure which is higher than MARVS (Maximum Allowable Relief Valve Setting)

These diagrams, made for propane, propylene and ammonia, are based on an ambient

temperature of +45 °C and a seawater temperature of +32 °C.

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8.2.2 Cooling-down of Cargo

The following diagrams show the time required for cooling-down of cargo, for operation

with selected compressor combinations and for various tank segregations:

Cargo

PROPANE

PROPYLENE

AMMONIA

ETHYLENE

For operation data and limits of compressors, see also Chapter 9.10.1.

All curves are based on the following ambient conditions:

air temperature 45 °C

seawater temperature 32 °C

8.2.3 Pressure Maintenance

Diagrams show the running time of one cargo compressor at different tank combinations at

varying conditions. These diagrams should be considered as a guide only.

Diagrams made for the following cargoes:

PROPANE

PROPYLENE

AMMONIA

ETHYLENE

ETHANE

For cargo temperatures/saturation pressures other than shown in the following diagrams,

interpolate to obtain time estimate.

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9 PLANT COMPONENTS AND SYSTEMS

9.1 Cargo Systems

9.1.1 General

Depending upon the duty in question, the cargo tanks and the components of the gas plant

including vent and drain system must be arranged into different cargo systems and

combinations.

This is achieved by setting of spool pieces within a selected system and respective

components and by dismounting other spool pieces, to segregate the selected system from

other systems and components.

Each segregation has to be carefully checked in order to avoid mixing of different cargoes

on the product side.

9.1.2 Cargo Systems and Cargo Tanks

At ONE or TWO GRADE SERVICE, the following combinations are possible:

Service Cargo System Tanks

ONE GRADE I 1, 2, 3

II -

TWO GRADE I 1,2 1,3 2,3

11 3 2 1

9.1.3 Cargo System Combinations

The following combination of cargo systems can be made:

Service: ONE GRADE System I only

ONE GRADE Systems I and II connected

TWO GRADE Systems I and II separated

9.1.4 Cargo Systems and Crossovers

Each cargo system, I and II, is firmly coordinated to the crossover set with the same

number, I or II. When both cargo systems are combined to a common cargo system, this

system can load/unload via one or both crossovers coordinated to the appertaining cargo

systems, I or II.

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9.1.5 Cargo Systems and Reliquefaction Plant Groups

The reliquefaction plant can be connected to one cargo system.

Alternatively, the reliquefaction plant can be split into two independent reliquefaction

groups, each reliquefaction group being connected to another cargo system.

Each reliquefaction group consists of the following main components:

- one cargo compressor with surge drum

- one flash drum

- one LPG condenser/vaporizer/desuperheater

- one ethylene condenser

- one cargo receiver

- one R22 screw compressor with

oil separator

oil cooler

economizer

condenser with receiver

The third cargo compressor with surge drum acts as spare and can be connected to

reliquefaction group I or II.

9.1.6 Cargo Systems and Booster Pumps

The booster pumps can be connected to any cargo system; both pumps to one cargo system

or each pump to a different system.

When both pumps are connected to the same system, they can be connected to operate in

parallel or in series.

The booster pumps can also be operated in parallel or in series when unloading with

warming-up.

9.1.7 Cargo Systems, Cargo Heater and Cargo Cooler

The cargo heater can be connected to any cargo system, as well as the cargo cooler.

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9.2 Cargo Tanks and Equipment

(see P+I Diagramm Pages 1, 12 and 13)

9.2.1 Cargo Tanks

There are three tanks, arranged in separate cargo hold spaces. The

tanks are self-supporting pressure vessels of bilobe construction and

are externally insulated.

For design data and geometric volumes, see para 1.4.

The tanks are divided by a longitudinal bulkhead into two tank halves.

The longitudinal bulkhead for all tanks is closed. The vapour spaces

of adjacent tank halves are connected by vapour balance lines, locate'

inside the tanks.

Each tank half has a gas dome which carries the deepwell pump, process

connections, connections for M & R equipment, the safety relief valve,

a manhole, and a pump sump.

9.2.2 Process Connections and Internal Tank Piping

Each tank half is fitted with:

- liquid loading line which also serves as purge line

- vapour connection

- upper purge line - upper spray line

- lower spray line

- stripping line which also serves as condensate line

- nitrogen padding

All tank connections have manual shutoffs, except the upper purge line. The vapour line,

loading line, stripping line, as well as the pump discharge line are additionally fitted with

emergency shutdown valves. The upper purge line is fitted with an emergency shutdown

valve only. These emergency shutdown valves are hydraulically operating ball valves. The

E.S.D. valves can be actuated locally -when released from CCR -, or remotely from

CCR - when released locally -. The valves close automatically by emergency shutdown.

9.2.3 Measuring and Control Equipment of Cargo Tanks

Each tank half is equipped with:

1 level indicator, full range, with local and remote indication, with high level switch

at 99% of tank volume and adjustable high level alarm and low level switch

1 high level switch at 99% with prealarm at 95% of tank volume

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Both 99% high level switches close all E.S.D. valves of this tank and stop all running

pumps.

Below for the real vsl only, kept as reference:

4 sample tubes with ball valves, for gas sampling at tank 0/50/99% level and in pump

sump

3 temperature elements on tank outside, for remote indication of temperature at tank

sump and tank wall temperatures at different heights

Each tank is equipped with:

2 temperature elements on portside, with local and remote indication in CCR of

temperature at 0/99% level, indicated on a common instrument by selector switch

and temperature high alarm in CCR and wheelhouse

2 temperature elements on starboard at 0/99% level with local and remote indication

in cargo control room, indication on a common instrument by selector switch and

temperature high alarm in CCR and wheelhouse

1 remote pressure indicator in CCR and wheelhouse for portside

1 local pressure indicator with pressure high alarm in CCR and wheelhouse

9.3 Tank Safety Relief Valves

In the simulator there is one relief valve on each tank, the pressure limit can be set by the

instructor or the user and same can be used to simulate change of P/V vale to be used.

On the real vessel there are 2 safety relief valves on each tank, both 4"/6". These relief

valves are pilot-operated valves AGCO Type 95. The set pressure of the safety relief

valves can be changed by means of an auxiliary setter, mounted onto the pilot. See also

manufacturer's instructions.

The following set pressures can be set:

3.2 bar g

Maximum allowable relief valve setting according to USCG. The pilot is adjusted to this

set pressure.

4.5 bar g

Maximum allowable relief valve setting according to IMO/GL. The 4.5 bar auxiliary setter

is mounted on top of the 3.2 bar pilot.

The changing of the set pressure should be carried 'out under the supervision of the master.

Changes in set pressures should be recorded in the ship's logbook and a sign posted in the

cargo control room and at each relief valve, stating the set pressure.

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9.4 Additional Pressure Relief System

9.4.1 General

On the real vessel the cargo tanks are fitted with an additional pressure relief system which

complies with IMO Volume III, Chapter 15 or Chapter 8, Para 8.3, respectively.

Based on this system, the filling limit for directly cooled cargoes at relief valve set

pressures 3.2 bar g and 4.5 bar g can be 98%. As a consequence of the guaranteed

minimum safety relief valve opening pressure of 0.5 bar g, the filling limit has to be

reduced at loading temperatures lower than saturation temperature corresponding to 0.5 bar

g. See also Chapter TANK .FILLING LIMITS.

In the event of fire, fusible elements provided on the stop valves in this system will melt

and cause the tank safety relief valves to open, when the pressure, corresponding to the

gauge vapour pressure of the cargo at the reference temperature is reached. This vapour

pressure is adjusted on a special pressure control valve which acts as a second pilot valve.

The safety relief valve will blow vapour off and thus prevent the tank becoming liquid-full.

9.4.2 Description and Function

In the real vessel the system makes use of an additional (second) pilot which is connected

in parallel to the main (first) pilot. It's function is blocked by a valve equipped with a

fusible plug melting between 98 and 104 °C. This additional pilot is a continuous variable

adjustment device for the set pressure of the main safety relief valve.

With the additional system, the set pressure of the main (first) pilot valve, adjusted for

MARVS, is not altered or influenced as it could be by erroneous assembly of additional

setters on the main pilot valve.

Moreover, the second pilot can always be adjusted to the actual tank pressure, i.e. the

optimum pressure adjustment for the loaded cargo conditions to achieve the maximum

filling limit.

The adjustment is made by means of a scale based on the tank pressure gauge reading.

Prior or during loading, respectively, the adjustable setter can be adjusted to a set pressure

higher than the main (first) pilot. Immediately after loading, the set pressure of the

additional pilot shall be adjusted slightly above the actual cargo vapour pressure (- +0;2

bar). As long as the fusible plug is not melted, the safety relief valve dome pressure cannot

be released, i.e. the valve does not blow off, caused by too low set pressure of the

additional pilot.

The reference temperature for calculation of the filling densities is the temperature

corresponding to this set pressure.

This set pressure should be adjusted by authorized persons on board (notation to be made

in the log book). The additional setter can be sealed or locked.

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The additional pressure relieving system (APRS) is to be operated in connection with a

control and monitoring of the cargo vapour pressure so that the pressure remains below the

set pressure of the APRS in normal conditions.

For further description of the adjustable pilot, the fuse plug controlled valve, installation,

operation, maintenance, test and adjustment of the additional pilot valve, see the

INSTRUCTIONS.

9.5 Tank Filling Limits

9.5.1 Requirements by IMO

1. According to IMO (IGC Resolution MSC.5(48)), Chapter 15, Para 15.1.2 > The maximum volume to which a cargo tank should be loaded is

determined by the following formula:

VL = 0 . 98 V PR / PL

where:

VL = maximum volume to which the tank may be loaded

V = volume of the tank

PR = relative density of cargo at the reference temperature

PL = relative density of cargo at the loading temperature and pressure <

2. The ratio X = VL/V is called in the following, the tank filling limit.

3. According to IMO Para 15.1.4 > For the purpose of this chapter only, "reference temperature" means:

.1 the temperature corresponding to the vapour pressure of the cargo at the set

pressure of the pressure relief valves, when no cargo vapour

pressure/temperature control as referred to in chapter 7 is provided;

.2 temperature of the cargo upon termination of loading, during transport, or at

unloading, whichever is the greatest, when a cargo vapour

pressure/temperature control as referred to in chapter 7 is provided. If this

reference temperature would result in the cargo tank becoming liquid full

before the cargo reaches a temperature corresponding to the vapour pressure

of the cargo at the set pressure of the relief valves required in 8.2, an

additional pressure relief valve complying with 8.3 should be fitted. <

9.5.2 Filling Limits at Various Relief Set Pressures

This vessel is fitted with a cargo vapour/temperature control according to IMO, Chapter 7

and an additional pressure relief system complying with IMO. Para 8. 3.

At relief valve set pressure 4,5 bar g (IMO) and 3.2 bar g (USCG), the filling rate for

cooled cargoes can be 98X of their geometric volume, if the conditions at loading end will

be kept as max. conditions.

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At a pressure of 0.5 bar g or lower, the additional pressure relief system is not applicable.

The filling limits for various media and cargo temperatures, as calculated in IMO, Para

15.1.2, are shown on the enclosed diagrams.

9.5.3 Filling Limits by Warming-up the Cargo during the Sea

Trip

The cargo can be warmed up by normal heat inflow to the cargo tanks or by cargo heater.

In this case, the filling limits must be calculated and reduced according to IMO regulations

and as written down in this operation manual under Para 3.5.1.

Use in this connection, the "THERMODYNAMIC AND PHYSICAL DATA OF

CARGOES", as filed under Ref. No. 31.

9.6 Deepwell Pumps

(see P+I Diagramm Pages 1, 12, 13)

9.6.1 Description

There are six pumps, one for each tank half.

They are multistage, centrifugal pumps of the deepwell type, lubricated

by cargo. The pumps have a double mechanical seal with an oil pressure

accumulator. They are coupled, via flexible coupling, directly with an

electric motor. The motor is designed for direct starting and is pro

vided with anticondensing heating.

9.6.2 Technical Data

Pump type SVANEHØJ NH 132/100-4-K+I

Rated capacity 170 m3/h at 125 m LC/85 m3/h at 31 m LC

Speed 1760 rpm/880 rpm

Max. density 0.990 t/m3

Max. power consumption 100 kW/13 kW

(at rated capacity and max. density)

Q-H curve see Sheet No. 94880-02/-03

9.6.3 Components

Each real pump is fitted with:

hand-regulating/return valve

hydraulically-operated E.S.D. valve

local pressure indicators for tank and discharge pressure

low ampere switch which stops the pump at too low flow (insufficient lubrication)

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high ampere switch which stops the pump at too high flow (pump cavitation)

flow switch which stops the pump at too low flow

The oil pressure accumulator contains sealing oil for the pump seal. The accumulator is

fitted with a pressure gauge and is pressurized with dry air.

9.6.4 Operation and Maintenance of Deepwell Pumps

See manufacturer's instructions.

The pump is started locally and can be stopped locally, from E-room or from CCR.

Before starting the pump, turn the shaft by hand to be sure that the pump is "free". Ensure

the pump cannot be started accidentally, when turning the pump.

During pump standstill, check that anticondensing heater in electric driving motor is

working.

9.6.5 Starting a Deepwell Pump

1. Establish the unloading route, but keep HR valve on DWP discharge only slightly

opened.

2. Ensure that the stop/return valves downstream (e.g. R 11005, R 12005 back to tank

are open. ( The following is not incl in the sim: The hand-operated valve DN 50 must be locked in

"open" position. The pump itself is interlocked to the E.S.D. valve DN 100 upstream (discharge line)

and E.S.D. valve DN 100 downstream (loading line). Only when these valves are open, the pump can

start.)

3. Start the pump according to manufacturer's instructions.

4. When the pressure gauge on DWP discharge shows stable pressure, adjust HR valve

on DWP discharge. The valve has to be adjusted under consideration of the tank

pressure and the discharge pressure. The required pressure difference depends on the

cargo density, the liquid level inside the tank and the requested discharge capacity.

The valve has to be adjusted within 20 seconds after pump start to avoid

switching-off by the ampere switch (EZAHL

11602/12602/21602/22602/31602/32602).

Attention:

When unloading with DWPs, close the ball valves in loading lines on all tank domes of the

used system (e.g. H 11002, H 12002 on tank 1). Otherwise, there can be a backflow.

Avoid backflow through DWPs, otherwise it can cause pump damage.

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9.7 Booster Pumps

(see P+I Diagramm Page 11)

9.7.1 Description

There are two booster pumps mounted on deck. The pumps are horizontal, single stage,

centrifugal pumps with double mechanical seal and an oil pressure accumulator. They are

coupled via flexible coupling directly with an electric motor. The motor is designed for

direct starting and provided with anticondensing heating.

9.7.2 Technical Data

Pump type SVANEHØJ GTB 125B-150/200

Rated capacity 300 m3 /h at 120 m LC

Speed 3570 rpm

Max. density 0.99 t/m3

Max. power consumption 139 kW

(at rated capacity and max. density)

Q-H curve see Sheet No. 94881-00

9.7.3 Components

Each real pump is fitted with:

butterfly valve and filter at suction side

HR valve and non-return valve at discharge side

local pressure indicators - on suction and discharge side

local differential pressure indicator which stops the pump, if the differential pressure

is too high or too low

local pressure indicator on pump seal

The pressure accumulator contains methanol for the pump seal. The accumulator is fitted

with a pressure gauge and pressurized with nitrogen, supplied from the nitrogen system.

(Accumulator of DWP is pressurized with compressed air of 5.5 bar g - this pressure would

be too low for the BP).

The Simulator system is a bit simplified on this point.

9.7.4 Duty of Booster Pumps

The booster pumps are operated when the discharge pressure of the deepwell pumps is not

sufficient to unload against backpressure from shore. Booster pumps are then operated in

series with deepwell pumps.

The ratio of booster pumps to deepwell pumps operating together is preferably between 1:1

and 1:4, optimum 1:2, possible 1:6. Larger ratios are uneconomical and should be avoided.

The booster pumps can be connected alternatively as follows:

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Two booster pumps operate in parallel (with 2 to 6 DWPs in series) on one cargo system,

or one booster pump (with 1 to 4 DWPs in series) operates on a separate system, or one

booster pump operates in series with the other booster pump (with 1 to 6 DWPs in series

on one cargo system and with 1 to 4 DWPs on two cargo systems).

Note:

Operating the booster pump(s) in series with deepwell pump(s) is not allowed for Ethyl

Chloride and Methyl Chloride because the design pressure of the piping would be

exceeded.

Alternatively, the booster pumps can be used for emergency unloading (if a DWP fails)

without deepwell pumps.

The booster pumps discharge to the liquid crossover I or II. For the process "unloading

with warming-up", the booster pump discharges via cargo heater.

9.7.5 Operation and Maintenance of the Booster Pump


The pump is started locally and can be stopped locally, or from CCR. During pump

standstill, check that anticondensing heating in the electrically driven motor is working.

9.7.6 Starting Deepwell Pumps and Booster Pump in Series,

without Recycling during Start-up Phase

5. Establish the unloading route - via BP -but keep HR valve on DWP discharge only

slightly opened, and keep HR valve on BP discharge only slightly opened.

6. Check the correct adjustment of the high/low ampere switch EZAHL of DWP and

ensure that the ball valves downstream of automatic recirculation valve back to tank

are open.

7. Start the DWPs according to manufacturer's instructions.

8. When their discharge gauge shows stable pressure, open HR valve on DWP

discharge fully. The DWPs fill the discharge piping and the BP with liquid cargo.

9. When the pressure gauge on BP suction shows stable pressure, start the booster

pump according to manufacturer's instructions.

10. When the BP is at full speed, adjust HR valve on BP discharge. This valve has to be

adjusted under consideration of the differential pressure of the DWP within 20 sec.

after DWP start.

11. Start second DWP of the same tank with HR valve on its discharge side slightly

opened. When its discharge gauge shows stable pressure, open HR valve fully.

12. Readjust the HR valve on BP discharge for the new situation with two or more

deepwell pumps, if necessary.

13. Perform only fine adjustment at the HR valves in the DWP discharge lines, just as

necessary to unload the tank halves evenly.

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9.7.7 Starting Deepwell Pumps and Booster Pumps, with

Recycling during Start-up Phase

When the backpressure from shore is higher than the discharge pressure of a DWP at

minimum flow, the cargo pumps have to be started with recycling during the start-up

phase.

14. Establish the unloading route - via BP -but keep HR valve on DWP discharge and BP

discharge only slightly opened, and keep crossover valve still closed.

15. Establish the recycling route, i.e. liquid crossover - stripping line - (spray line) - tank.

16. Check the correct adjustment of the high/low ampere switch EZAHL of DWP.

17. Start the DWP according to manufacturer's and LGA's (Item 3.6.5) instructions.

18. When its discharge pressure shows stable pressure, open HR valve on DWP

discharge fully. The DWP fills the discharge piping and the BP with cargo.

19. When the pressure gauge on BP suction shows stable pressure, start the booster

pump with its discharge valve fully open.

20. When the BP is at full speed, adjust the hand-operated ball valve(s) on tank dome in

the stripping line under consideration of the minimum flow 20 m3/h for DWPs, 30

m'/h for BPs each, indicated by differential pressure (see Q-H curves of DWPs and

BPs) and to ensure that the pressure in the crossover is higher than the pressure in the

shore line.

21. Now open the crossover valve, close the recycling route. Adjust the HR valve in BP

discharge under consideration of the differential pressure of BP and DWP.

22. Start second DWP of the same tank with HR valve on its discharge only slightly

opened. When the pump is at full speed, open HR valve fully.

23. Readjust the HR valve on BP discharge fully for the new situation with two or more

deepwell pumps, if necessary.

24. Perform only fine adjustment at the HR valves in DWP discharge lines, just as

necessary to unload the tank halves evenly.

9.7.8 Operating Booster Pumps in Series

At very high backpressure from shore, the two booster pumps can be operated in series

(and in series with 1 to 6 DWPs). This kind of operation is not allowed for all

non-refrigerated cargoes as well as for VCM, Ethyl Chloride and Methyl Chloride.

The starting sequence follows the same logic as detailed in the 2 previous chapters.

The design pressure of the piping system for cargo handling is 25 bar g.

In this combination; the BPs in series with DWPs could develop a max. discharge pressure

by unloading ammonia, the medium with the highest density of all allowed cargoes, of

20.5 bar g at atmospheric tank pressure or 23.4 bar g at a tank pressure of 4.5 bar g,

respectively.

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9.8 Crossovers and Piping on Deck

There are two sets of crossovers, one for each cargo system at two grade service. Each set

consists of one liquid and one gas crossover. Each crossover has flanged connections at SB

and PS.

9.8.1 Each connection for liquid and vapour crossovers is

fitted with:

hand-operated butterfly valve

a hydraulically-operated E.S.D. valve

The valve can be actuated locally, remotely or automatically by emergency

shutdown. .

local indicator between E.S.D. valve and presentation flange

purge connection between butterfly valve and presentation flange

Each liquid crossover is additionally fitted with:

local and remote pressure indication with a high pressure switch to close the E.S.D.!

valves on crossover and to switch off DWPs and BPs at 24 bar g

Each liquid line i provided with a loading filter. The filter element has to be fitted between

presentation flange and loading arm before loading cargo.

Pipes on deck and inn the gas machine room connect the various components of the cargo

system, cargo tanks, crossover, reliquefaction plant, cargo heater, booster pumps and vent

masts.

The piping allows 4 by means of valve connections, spool pieces and hoses:

- arrangement of different tank segregations for one or two grade

service

- connections from tanks and gas plant to vent masts for venting and

purging

- connections for inert gas supply

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9.9 Reliquefaction Plant

(see P + I Diagram, Pages 2 - 8)

9.9.1 Description of the Reliquefaction Plant

The reliquefaction plant is installed in the cargo compressor room and

comprises the following main components:

- 3 surge drums

- 3 cargo compressors, type 2K140-2B

- 2 flash drums

- 2 LPG condensers/vaporizers/CZ desuperheaters

- 2 ethylene condensers

- 2 cargo receivers

- 2 R22 plants

- control valves

The reliquefaction plant can be split into two independent relique

faction groups, Groups I and II.

The reliquefaction groups consist of the following main components:

Group

I II

Surge drum B 41601 B 43601

Cargo compressor 2K140-2B V 41601 V 43601

Flash drum B 51602 B 52602

LPG condenser W 51652 W 52652

Ethylene condenser W 51651 W 52651

Cargo receiver B 51601 B 52601

R22 plant 61…. 62……

Each R22 plant comprises the following main components:

R22 compressor

R22 condenser

R22 receiver

R22 filter drier

R22 economizer

Oil pump

Oil separator

Oil cooler

Oil filter

For operation without R22 cycle:

The residual main components (cargo compressor V 42601, surge drum B 42601)

can be selectively connected to reliquefaction group I or II.

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Each condenser system and each flash drum is designed to handle the capacity of two

compressors.

For operation with R22 cycle:

The same connections as a.m. are possible but operate one of the compressors V

41601/V 42601 or V 43601/42601, respectively, with 50% capacity.

Each ethylene condenser is designed to handle the capacity of 1.5 compressors (one

with 100%, one with 50% capacity).

9.9.2 Duty of the Reliquefaction Plant

The reliquefaction plant is used for the following duties:

- to maintain the tank pressure during voyage

- to cool the cargo down during voyage

- to liquefy vapour (displaced vapour, flash gas, boil-off) during loading

- to cool cargo down during loading

- to cool the cargo tanks down before loading

- vaporizing of liquid with or without operating of compressor(s)

The reliquefaction processes for the different duties depend on the kind of cargo, tank

pressure and cargo temperature.

9.9.3 The Reliquefaction Process

The following chart shows the possibilities to cool the cargo:

Refrigeration System

Direct System Combined System

acc. to IMO 7.2.4.1 acc. to IMO 7.2.4.3

3 Cargo Compressors 3 Cargo Compressors

(Sulzer) (Sulzer)

2 Seawater-cooled 2 Refrigerant Compressors

Condensers 2 R22-cooled Condensers

Media: Media:

Anhydrous Ammonia 1)

Ethylene

Butadiene Ethane

Butane Propylene 2)

Butane-Propane Mixtures Commercial Propane 2)

Butylene

Propylene

Ethyl Chloride

Methyl Chloride

Vinyl Chloride (VCM)

Propane

Commercial Propane

C4/C5 Fraction

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1) at low suction 2) only at low suction

pressure with in- pressure, otherwise

termediate cooling use direct cooling system

Description: Description:

Chapter 3.9.4 Chapter 3.9.5

9.9.4 The Reliquefaction Process as the Direct System

The evaporated cargo is compressed, condensed and returned to cargo tanks.

There are two possibilities to operate the reliquefaction process with the direct system:

- with intermediate cooler (flash drum)

- without intermediate cooler (flash drum)

9.9.4.1 Process with Intermediate Cooler

This process will be used normally only for ammonia service at low suction

pressure/temperature to avoid unallowed discharge temperatures.

Vapour from the tank is sucked off by the cargo compressor(s) first stage. The compressed

vapour is discharged and submerged into t-he intermediate cooler (flash drum) which is

partly liquid filled, so that the hot gas loses its superheat by vaporizing of liquid cargo. The

gas temperature then corresponds to intermediate pressure. The second stage of the cargo

compressor sucks off the vapour from the intermediate cooler at saturation conditions.

The compressed vapour is discharged into the seawater cooled condenser, where it will be

desuperheated and condensed. Because the compression ratio of some cargoes is relatively

high, the compressor compresses the gas in 2 stages.

The condensate will be collected in the cargo receiver. The liquid level in the cargo

receiver is controlled by the control valve. In the level control valve, the condensate

expands from condensing pressure to intermediate pressure.

The forming flash gas together with the discharged gas from first stage and vaporized

liquid, as a consequence from desuperheating, is sucked off from compressor second stage.

The liquid from the intermediate cooler is expanded to tank pressure via a level controlled

expansion valve on vessel outlet.

Vapour route:

tank - compressor 1st stage - intermediate cooler -compressor 2nd stage - condenser

Condensate route:

condenser - cargo receiver - level control valve -intermediate cooler - level control

valve - stripping or liquid line - tank

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9.9.4.2 Process without Intermediate Cooler

The process is the same as described before, but the discharged gas 1st stage is sucked off

by 2nd stage directly (without passing the intermediate cooler). The condensate is

expanded to tank pressure by level controlled expansion valve on cargo receiver outlet

without intermediate expansion into the intermediate cooler.

Vapour route:

tank - compressor 1st stage - compressor 2nd stage -condenser

Condensate route:

condenser - cargo receiver - level control valve - stripping or liquid line - tank

9.9.5 The Reliquefaction Process as Combined System

The evaporated cargo is compressed and condensed in a cargo/refrigerant heat exchanger

and returned to the cargo tanks.

The intermediate cooler will only be used for ethylene and ethane service. The LPG

condenser (CHE) will be used as gas cooler, also for ethylene and ethane only:

as gas cooler 1st stage discharge side at high suction temperatures (Start-up)

as gas cooler 2nd stage discharge side at low suction temperatures (normal operation)

9.9.5.1 Process with Gas-cooling after 1st Stage

This process is required at high suction temperatures, e.g. during start-up phase, especially

for ethylene and ethane service. The hot gas discharged by the 1st stage of cargo

compressor is cooled with seawater in the LPG condenser. The hot gas discharged by the

2nd stage of cargo compressor is desuperheated and condensed with refrigerant in the

condenser/R22 evaporator and collected in the cargo receiver.

By ethylene and ethane service, the condensate will be expanded into the intermediate

cooler. The flash gas is mixed with the hot gas coming from discharge side 1st stage of

cargo compressor (hot gas from 1st stage is not submerged).

The further direction of the condensate is the same as described in the processes before.

Vapour route:

tank - compressor 1st stage - gas cooler/gas cooler (CHE) - compressor 2nd

stage - ethylene condenser/R22 evaporator

Condensate route:

ethylene condenser/R22 evaporator - cargo receiver - level control valve - intermediate

cooler * - level control valve * - stripping or liquid line - tank

* only by ethylene and ethane service

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9.9.5.2 Process with Gas-cooling after 2nd Stage

This is the normal process for reliquefying of ethylene and ethane, as well as for propylene

and commercial propane at low suction pressure, when the required low suction

temperature is reached, but for propylene and commercial propane service, the use of

intermediate cooler is not required.

The flash gas coming from the intermediate cooler is mixed with the hot gas from 1st

stage. This gas stream with an intermediate (not saturated) temperature is sucked off by

2nd stage of compressor.

The discharged gas from the 2nd stage is cooled by seawater in the gas cooler (LPG

condenser) down to a temperature which is some °C above seawater temperature.

The pre-cooled gas will be desuperheated further and condensed in the condenser/R22

evaporator by using the R22 circuit.

The further process is the same as described before.

Vapour route:

tank - compressor 1st stage - compressor 2nd stage - gas cooler (LPG

condenser) - condenser/R22 evaporator

Condensate route:

condenser/R22 evaporator - level control valve - intermediate cooler

- level control valve * - stripping or liquid line - tank

* only by ethylene and ethane service

9.9.6 Components of the Reliquefaction Plant

(see P + I Diagram, Pages 4 - 6)

9.9.6.1 Cargo Compressor

Type Sulzer 2K140-2B

- oilfree type for 2-stage compression

- double-acting 2-cylinder compressor

- driving gear is force-lubricated by an integral oil pump

- cylinder heads

- crossheads and guide bearings are cooled by an external glycol

water circuit

- manual capacity control 50/100%

- directly coupled to electric motor

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Equipment

- butterfly valves in suction and discharge line

- non-return valves in discharge lines

- safety controls and indicators for gas pressures and temperatures

- safety controls and indicators for oil pressures and glycol flow

- safety valves in discharge lines and as protection against high

diff. pressure at the stages

- safety shutdown switches and alarms for protection against mal

operation

Electric motor, for direct starting

Power 242 KW

Speed 595 rpm

Type of construction B3

Enclosure type IP 44

The compressor in the gas machine room is connected to its electric motor in the adjacent

E-room by an intermediate shaft with a gastight bulkhead penetration. The bulkhead

penetration is provided with a mechanical seal which is oil-lubricated and cooled by an

external glycol water circuit. A temperature switch stops the motor, if the oil temperature

rises too high.

The compressors are to be started or stopped locally and they can also be stopped from the

CCR.

Compressor V 41601 is firmly connected to reliquefaction group I.

Compressor V 43601 is firmly connected to reliquefaction group II.

Additionally, there is a selector switch in the CCR for choosing the

following positions:

- compressor V 42601 to reliquefaction group I (control instruments of

group I will act to V 42601 and V 41601)

- compressor V 42601 to reliquefaction group II (control instruments of

group II will act to V 42601 and V 43601)

- all compressors to both reliquefaction groups (one grade, all control

instruments of both groups will act to all compressors)

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9.9.6.2 Droplet Separator (surge drum)

There is a droplet separator in the 1st stage suction line of each compressor. The droplet

separator is designed to vaporize any possible liquid droplets in the vapour by means of hot

gas. The high level switch stops the compressor. Overall dimensions: 650 x 975 (diameter

x cyl. height)

Equipment:

demister

level indicator

high level switch with alarm in CCR

9.9.6.3 Cargo Condenser, Vaporizer, Desuperheater (LPG Condenser)

The heat exchanger is designed to decrease the superheat of hot gas before condensed with

R22 circuit, to condensate the cargoes of the DIRECT CYCLE and to vaporize several

cargoes by seawater.

It has the following dimensions: 840 x 6500 mm (diameter x tube bundle length).

The heat exchanger is a shell and tube heat exchanger, seawater flows in the tubes.

For condensing, the heat exchanger is fitted with an HR valve to vent incondensable gases

For vaporizing of cargo, the heat exchanger is fitted with a pressure control valve and a

level control valve to avoid freezing or overfilling, respectively.

Other equipment

local indication of cargo pressure, temperature and level

level indicator with switch which stops the compressor, if the level of liquid rises too

high simultaneously, the level control valve will be closed and an alarm will be given

to the CCR

local indication of seawater temperature

If the seawater temperature drops too low, the temperature switch inside the tubes closes

the pressure control valve and level control valve.

If the cargo temperature drops too low, another temperature switch inside the shell also

closes the pressure control valve and the level control valve.

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9.9.6.4 Intermediate Cooler (flash drum)

The cargo flash drum is a vertical vessel. It is designed to desuperheat the discharge gas

from cargo compressor 1st stage by mixing with flash gas or by vaporizing of condensate,

if the hot gas is submerged in the liquid.

Dimensions: 950 x 2400 mm (diameter x height)

Equipment

demister

local pressure indicator

level controller with control valve

local level indicator with high level switch, which stops all compressors which work

on this flash drum Simultaneously, an alarm will be given to the CCR.

9.9.6.5 Cargo Receiver

This is designed to accumulate the condensed cargo.

Dimensions: 450 x 1500 mm (diameter x cylindrical length)

Equipment

level indicator with controller

level control valve

level alarm low in CCR

level alarm high in CCR

local temperature/pressure indicator

9.9.6.6 R22 Compressor

- Type Mycom F2520 CSL-SM-61

- double-stage screw compressor with economizer part

- lubricated by external oil pump

- manual and automatic capacity control 0 - 100%

- directly coupled to electric motor via intermediate shaft,

same as for cargo compressor

Equipment

stop, butterfly and non-return valves

filter on suction side and intermediate cooling line

safety controls and indicators for refrigerant and oil pressures and temperatures

oil filter in oil circuit

oil separator for oil return

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Electric motor for starting

Power 330 kW

Speed 3550 rpm

Type of construction B3

Enclosure type IP 44

9.9.6.7 R22 Condenser

The R22 condenser is a shell and tube heat exchanger with receiver. R22 is condensed on

shell side by warming up of seawater in the tubes. The condenser is fitted with a pressure

indicator on shell side and a temperature indicator for seawater outlet temperature. The

combination R22 receiver/condenser is designed to accumulate the whole charge R22 of

the circuit. It is fitted with a temperature indicator and a level indicator.

If the level of R22 in the cargo receiver drops too low, an alarm will be given in CCR.

Dimensions: condenser 508 x 3660 mm (diameter x tube bundle length) receiver 400 x

3000 mm (diameter x length)

9.9.6.8 R22 Evaporator/Ethylene Condenser

Shell and tube heat exchanger for dry expansion of R22 refrigerant. Tube side is divided

into three compartments, each fitted with a thermostatic expansion valve for R22 injection.

Ethylene, ethane, commercial propane and propylene can be condensed on shell side.

Note:

The heat exchanger is designed for a min. temperature of minus 55 °C. Do not expand the

gas at shell side below this design temperature.

Dimensions: 650 x 4500 mm (diameter x tube bundle length)

9.9.6.9 R22 Economizer

Injection cooler, designed to subcool the R22 condensate and to avoid high compressor

discharge temperature.


9.9.6.10 R22 Filter/Drier

Welded in liquid line, with shutoff valves.

9.9.6.11 Oil Separator

Designed to separate the oil from R22 discharge gas to a value of approx. 200 ppm. The

separator is fitted with a level glass, and a heating coil by external glycol circuit.

Overall dimensions: 812 x 1800 mm (diameter x cyl. height)

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9.9.6.12 Oil Cooler

Shell and tube type to cool oil by seawater in tubes.


9.9.6.13 Base Frame

One R22 compressor with oil separator, R22 economizer the oil cooler and electric motor

are mounted on one base frame and are internally piped and wired.

9.9.6.14 Refrigerant Control

The R22 evaporator is divided into 3 compartments, each with its own refrigerant control.

Each control set comprises

a thermostatic expansion valve (TV), to control the flow

a hydraulically operated on-off valve

a solenoid GV, (located in E-room), to initiate closing of the on-off valve

a strainer in liquid line upstream expansion valve

When the compressor is stopped, all on-off valves are closed. When compressor starts, one

of the a.m. controls is activated. The second control set is activated by 33% load of R22

compressor. The last control device is turned on at 66% load.

Compressor load (approx.) Evaporating surface

0 -33% ~ 33%

33 -66% ~ 66%

66 - 100% 100%

This arrangement gives automatic adaption of refrigerant capacity to compressor capacity

in regard to optimization of control valve function and oil return.

The R22 economizer is controlled by a thermostatic expansion valve (TV), likewise fitted

with a shutoff valve and a hydraulicallyoperated on-off valve in the liquid line. At a

compressor load above 50%, the economizer is activated by-opening the on-off valve. TVs

are already adjusted to give optimum performance. Readjustment of TV superheat is not

normally necessary. Adjustment of thermostatic expansion valves is a difficult matter.

Improper adjustment can cause compressor failure. Therefore, valves should only be

adjusted by an expert.

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9.10 Operation of the Reliquefaction Plant

9.10.1 Operation Data and Limits of Compressors

Below is from the real vessel, sim procedure might differ slightly:

Generally, the suction pressure of Sulzer compressors will only be

between approx. 0 bar g and 3.0 bar g

adjust the pressure switch high on 1st stage suction side to 3.2 barg and the pressure

switch low on both suction sides to -0.1 barg

adjust also the pressure indicator controller (PIC) in the gas suction line to 3.0 bar g

For the correct operation at the PIC, select one of the two pressure transmitters (PT)

(e.g. PT 41201,01 or PT 41^01.02) acc. to the measuring range by operating the

3-way valve in outlet line from PT to PIC.

for special adjustments of PIC, see the following table of different media.

Medium Operation/Limitation

Ethylene - For cooling down of cargo in 3 tanks with 2(3)

compressors 2K140-2B; maximum allowable

suction pressure at 1st stage is 0.6 (0.1) bar g

(adjustable at the PIC in gas suctionline), otherwise

the Mycom screw will be overloaded.

- Always operate with flash drum but without

submerging the hot gas into the condensate.

- The LPG condenser(s) will be used as gas cooler.

- For pressure maintenance, one compressor

2K140-2B and one Mycom screw is always

sufficient.

Ethane - See ethylene; max. allowed suction pressure at 1st

stage suction is 1.0 bar g.

. C-Propane Cooling-down of cargo by one grade normally

max. ethane content with 2 or 3 compressors:

2.5 mol%

- Till a tank pressure of 1.3 bar g, the operation will

be made with the LPG condensers

- Below this tank pressure, use max. 2 com pressors

and 2 Mycom screws by throttling the suction

pressure of the Sulzer to 0.4 bar g at the pressure

indicator control (PIC) in gas suction.

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- In both cases, the flash drum will not be used.


- It is necessary to lead the condensate through the

lower purge into tank, because of limitation of

ethane concentration in the gas phase.

- For pressure maintenance, one compressor and one

screw is sufficient.

Propane Cooling-down of cargo by one grade normally with 2

or 3 compressors, pressure maintenance with 1

compressor:

The flash drum will not be used.

Propylene Cooling-down of cargo by one grade normally

with 2 or 3 compressors:

- Till a tank pressure of 1.2 bar g, the operation will

be made with the LPG condenser(s). Blow this tank

pressure, use 2 compressors and 2 Mycom screws by

throttling the suction pressure of the Sulzer to 0.4

bar g at the PIC in gas suction.

- The flash drum will not be used.

VCM See propane; max. allowed suction pressure at

1st stage is 0.5 bar g.

The temperature switch high on 1st and 2nd

stage discharge has to be adjusted to 90 °C.

Butylene See propane; max. allowed suction pressure at


i/n-Butane See propane; max. allowed suction pressure at


Butadiene See propane; max. allowed suction pressure at


The temperature switch high on 1st and 2nd

stage discharge has to be adjusted to 60 °C.

NH3 Cooling-down of cargo with 2 or 3 compressors,

pressure maintenance with 1 compressor:

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- Below a tank pressure of 1.5 bar g, use the flash

drum in a way that the hot discharged gas of 1st

stage will be submerged in the condensate.

Methyl Chloride - The max. allowed suction pressure at.1st stage is 1,5

bar g.

Remarks:

The max. allowed suction pressure according to the afore-mentioned table has to be

adjusted at the PIZHL 41202/42202/43202.

The min. suction pressure has to be adjusted at the PIZHL 41202/42202/ 43202 and PIZL

41205/42205/43205 to -0.1 bar. When evacuating tanks, PIZHL 41202/42202/43202 has to

be adjusted to -0.5 bar (see also Chapter 3.11.3).

The max. allowed discharge temperature is adjusted to 120 °C on TIM 41102/42102/43102

at the 1st stage and to 150 °C on TIZH 41104/42104/ 43104 at the 2nd stage. At butadiene

and VCM the temperature switches of the 1st and 2nd stage have to be readjusted to 60 °C

or 90 °C in order to avoid polymerization.

The max. admissible differential pressure at the 1st stage is adjusted to 5.8 bar on PDZAH

41203/42203/43203.

The max. allowable differential pressure at the 2nd stage is adjusted

to 13.7 bar on PDIZH 41206/42206/43206.

9.10.2 Operation of the Direct Cycle

9.10.2.1 Cargoes

The direct cycle (corresponding to IMO - Para 7.2.4.1) is used for the following cargoes:

ammonia

butadiene

i/n-butane

butylene

VCM

Propylene 1)

propane

commercial propane 1)

methyl chloride

ethyl chloride

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1) Operation with cascade cycle below a special tank pressure required. For operation

data and limits, see 3.10.1.

9.10.2.2 Sequence of Start-up

25. Ensure that the glycol water cycle is operating properly and the GW temperatures are

within the limits specified by Sulzer.

26. Set selector switch

to subordinate the compressor V42601 to the selected reliquefaction system

(Group I or II)

to subordinate the compressor V42601 to both reliquefaction systems, if

necessary.

27. Adjust the high/low pressure switch points on 1st and 2nd stage suction side to 3.2

bar g/-0.1 bar g. Adjust the pressure indicator control (PIC) according to 3.10.1.

28. Establish seawater supply through glycol water cooler.

29. Establish seawater supply through LPG condenser or R22 supply for ethylene

condenser and seawater supply through LPG condenser.

30. Establish passage of cargo according to process sheet with or without flash

drum - see Operation Limits.

31. For starting sequence of the compressor, take care that the bypass valves (H41014,

H41015, H42014, H42015, H43014, H43015) of 1st and 2nd stage are open.

32. Start cargo compressor according to Sulzer's instructions.

33. If compressor is running, close bypass valves of compressor slowly.

9.10.2.3 Maintenance


Check periodically

cargo compressor oil level

pressure and temperature indicators,

1st and 2nd stage discharge temperatures (compressor safety valve leaking?)

2nd stage discharge pressure

level of cargo receiver (level control valve working?)

level of flash drum (level control valve working?)

level of surge drum

When a high level switch has stopped the compressor, clear reason for liquid

accumulation. If the high level in the liquid separator has stopped the compressor, drain the

separator and restart compressor with throttled suction valve. Monitor further operation

carefully.

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9.10.3 Operation of the Cascade Cycle

9.10.3.1 Cargoes

The cascade cycle (corresponding to IMO - Para 7.2.4.3) is used for the following cargoes:

propylene 1)

commercial propane 1) (max. ethane content 2.5 mol%)

ethane

ethylene

1) Operation with cascade cycle below a special tank pressure required.

For operation data and limits, see 3.10.1

9.10.3.2 Sequence of Start-up of the Cascade Cycle

34. Start freshwater flow through freshwater heater in good time ahead of compressor

start. The freshwater must have reached 35 °C before compressors are started.

35. Establish seawater supply through heat exchangers: R22 condenser(s), LPG

condenser(s) (if the hot gas of compressors 1st or 2nd stage discharge is

desuperheated), freshwater cooler, oil cooler.

36. Establish passage of cargo and R22 cycle.

37. Open the butterfly valve (K 09044 and/or K 09043) back to tank.

38. Start compressors with 50% load according to 3.10.2.2 and Sulzer's instructions.

39. Throttle the butterfly valve(s) in gas discharge line so that the pressure on 2nd stage

discharge rises a little bit above condensing pressure.

40. Start one R22 crew according to instructions.

41. Close the butterfly valve(s) in gas discharge line slowly by monitoring of gas

temperature and pressure on 2nd stage discharge. i

42. If the compressor and 822 screv run is balance, cargo is condensed and accumulated

in the cargo receiver. Now, cargo flash drum can be involved.

43. If required, a (second compressor can be started. Till SO% load of this compressor,

one ethylene condenser has to be used, at 100% load, the secon ethylene condenser

has to be used.

44. If the capacity of the R22 screw is not sufficient, start the second R22 screw.



Check periodically

cargo compressor oil level

level of cargo receiver (level control valve working?)

level of surge drum

level of flash drum (level control valve working?)

pressure and temperature indicators

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1st and 2nd stage discharge temperatures (compressor safety valve leaking?)

2nd stage discharge pressure (incondensable gas: see Chapter 3.10.5)

9.10.4 Standstill Periods

(only for cargoes with intermediate cooling)

To avoid too high pressure in flash drum (B51602, B52602) during standstill of the

reliquefaction plant, the following armatures have to be open:

ball valve H 51040 and/or H 52040

bypass ball valve on cargo compressor

V 41601 . H 41014, H 41015 and/or.

V 42601 . H 42014, H 42015 and/or

V 43601 : H 43014, H 43015

one of the following tank valves:

H 11002/12002/21002/22002/31002/32002

V 11011/12011/21011/22011/31011/32011

After start of Sulzer compressor, the bypass valve on 2nd stage has to be closed at first to

reduce the pressure in cargo flash drum. When the required intermediate pressure is

reached, close bypass valve first stage.

9.10.5 Incondensable Gas in Ethylene - or LPG Condenser

9.10.5.1 General

Incondensable gas can lead to operational difficulties and compressor stop.

Incondensable gas is e.g. air, inert gas or nitrogen and

appears especially after loading and purging with air or inert gas

cannot be reliquefied by the installed reliquefaction plant

collects in the upper part of the cargo condensers during relique faction service

increases discharge temperature of cargo compressors

increases condensing pressure and power input of compressors

decreases reliquefaction capacity

can be determined by comparison of condenser pressure and condensate temperature.

9.10.5.2 Check for Incondensable Gas

45. Read pressure (P cond) on PI 51202/52202 at cargo condenser or on PI 51206/52206

at ethylene condenser.

46. Read temperature of the condensate in cargo receiver at TI 51102/ 52102. Convert

this temperature to saturation pressure (Psat) by means of property table or vapour

pressure diagram.

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47. Compare these two values. (Use same units bar abs or bar g).

48. If (P cond) is considerably larger than (P sat), there is incondensable gas in the plant.

9.10.5.3 Removal of Incondensable Gas

49. The LPG and ethylene condensers are fitted with an HR valve, designed to remove

incondensable gas to the vent system. The HR valves are hand-operated. As a matter

of fact, if the HR valve is opened, a mixture of incondensable gas and cargo vapour

removes itself from the condenser.

50. Check for incondensable gas whenever the compressor discharge pressure and

discharge temperature are considerably above normal operation values.

51. If there is incondensable gas, the HR valve has to be opened long enough to remove

the incondensable gas, but short enough to avoid loss of cargo gas.

52. The incondensable parts will be vented normally through the rent system to

atmosphere. If venting to atmosphere is not allowed, the incondensable parts can be

vented via a swing elbow back to a tank.

9.10.6 Operation of the R22 Cycle

(see P+I Diagram)

9.10.6.1 Starting the R22 Compressor for Reliquefaction

53. See manufacturer's instructions.

54. Start freshwater flow through oil separator a good time ahead of compressor start.

The oil must be lukewarm before compressor is started.

55. Before each start, check if the capacity control (sliding valve of compressor) is at 0%

load. This can be seen at the unloader indicator. If the indicator needle shows more

than 0% load, start oil pump and pushbutton "less" till the indicator needle shows OX

load. Then stop the oil pump by button "stop" and wait 10 minutes to allow oil to

drain out of the compressor in order to avoid damage. (The compressor cannot be

started before time has elapsed.)

56. Start compressor according to instructions by pushing the button "start". At first,

only the oil pump is in operation. The R22 compressor starts after 10 sec.

57. Capacity is controlled automatically by PIC 61201/62201 (suction pressure

regulation).

58. The max. discharge pressure is adjusted (PZH 61208/62208) to 17 bar g and the max.

discharge temperature (TZH 61110/62110) to 90 °C.

59. The capacity can De controlled automatically or manually. Therefore, the selector

switch HSHL 61201/62201 has to be turned to "manual" or "automatic". In case of

"manual" the capacity can be controlled by pushing the buttons "more" or "less". In

both cases, the motor is protected against overload by automatic adjustment of

capacity.

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60. When the compressor has been stopped, the oil pump remains in operation until the

indicator needle shows OX load. In case of emergency shutdown, the capacity

controller must be readjusted according to Item 3 before compressor starting.



Check periodically

oil level at oil separator

The oil level should be min. 150 mm above the lower flange of the

sight glass. If the level is too low, fill up oil via a hand

pump at the drain valve of the sight glass or drain valve of

the oil separator. Be careful that no air is pumped into the

separator.

Recommendation: Fill up to 200 mm above the lower flange (see also

manufacturer's instructions). Do not store oil in open air.

pressure in oil supply line

differential pressure of oil filter (filter clogged)

level of R22 receiver

pressure indicator r1 61210 or 01416 and r1 62210 vi 62216 VIA con- PI

61209/62209 on oil separator and PI 61212/62212 in condensate line (rupture disc

burst - loss of refrigerant)

continuous increase of condensing pressure (scaling of condenser

tubes/incondensable gas in R22 system)

shaft seal of compressor (leakage less than 3 cc per hour) and oil pump

suction filters of compressors, filters before thermostatic expansion valve and filter

driers

the plant for R22 leaks

After mechanical completion, the R22 circuit is leak-tested and can be considered

leak-tight. Loss of R22 refrigerant may occur by leaks and by service/repair works.

Leaks may occur primarily at improper connections (mostly due to temperature

variations and material settling, vibrations or ship motion) or at compressor shaft

seals and valve spindle seals (wear, defect).

It is therefore mandatory to leak-test the R22 circuit in regular intervalls, after repairs

and maintenance works and when observing any substantial R22 loss by suitable

means. Suitable means can be the use of a halide torch (only when the ship is

gasfreed), electronic leak detector, soap solution, individual check of potential leak

sources.

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If the ship's crew does not have specific experience with these procedures, it is

necessary to use the services of competent refrigeration servicemen for these jobs.

It is unavoidable to have some small R22 losses at normal service works, such as

change of compressor oil, filters and filter driers. Also during these works utmost

care should be exercised to keep the R22 loss to a minimum. These losses must be

compensated by addition of new R22. Whenever the recharged R22 quantity exceeds

tolerable limits (some sources say 2 small R22 cylinders per unit per year), there is

something wrong. The R22 circuit should be thoroughly checked and the fault

rectified before recharging R22.

9.10.6.3 Incondensable Gas in R22 System

Incondensable gas in an R22 system is usually a sign of incorrect handling during

recharging, change of drier or other system repairs. It is mostly accompanied by moisture

in the system (freezing of TV needles, increase ageing of lube oil). Presence of

incondensable gas is indicated by increased condensing pressure.

In order to draw off incondensable gas

remove one safety valve, rupture disc and rupture disc holder of the changeover

valve of the R22 condenser

vent incondensable gas/R22 mixture at changeover valve on condenser

mount rupture disc, rupture disc holder and safety valve on the changeover valve

change filter drier insert

change oil, if necessary

repeat procedure after some time, if required

9.10.6.4 Vacuum Service

The compressors are protected against low suction pressure by PZL 61205/62205. The

switches are adjusted to minus 0.51 bar g. If the compressor had been stopped, it is

necessary to increase the pressure in the evaporator or on the suction side to approx. minus

0.1 bar g, because the suction pressure switch has a min. reset of 0.4 bar. After pressure

increasing (monitor pressure indicator PI 62202/61202), the compressor can be started

again. An override of the suction pressure switch allows evacuation of the R22 system for

repairs, etc.

9.10.6.5 Extended Out-of-Service Period

In case the plant goes out of service for an extended period, it is recommended to store the

R22 charge in the receiver with all stop valves closed. In order to store the charge in the

receiver, close the valve at receiver outlet and operate the compressor on the system while

seawater flows through the condenser. When the whole charge is contained in the receiver,

stop. the compressor, stop seawater flow and close the valve at condenser inlet. When

re-entering service, the R22 plant should be leak-tested again.

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9.11 Operation of Cargo Compressor for Other Duties

9.11.1 Other Duties

"Other duties" are duties other than reliquefaction:

- vapour return to shore during loading

- pressurizing tanks for unloading, stripping and emergency unloading

- evacuating of tanks and cargo plant

- purging of cargo tanks and gas plant with product

9.11.2 Starting the Cargo Compressor

61. Ensure the glycol water cycle is operating properly and the GW temperatures are

within the limits specified by Sulzer.

62. Adjust the high/low pressure switch points on 1st stage suction side to 3.2 bar g/-0.1

bar g (normally). In case of evacuating of tank(s), adjust the high pressure switch on

1st stage suction to 3.2 bar g and the low pressure switch under consideration of

3.11.3. Adjust the PIC to 3.0 bar g.

63. Establish seawater supply through the glycol water cooler.

64. Establish vapour flow route.

65. Start the cargo compressor according to Sulzer's instructions.

9.11.3 Vacuum Service

The cargo tanks are designed for a vacuum of 0.5 bar a related to atmospheric pressure. A

greater pressure in hold space has to be considered. At vacuum service, the pressure switch

low in the compressor suction line is to be adjusted under consideration of hold space

pressure.

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9.12 Combined Heat Exchanger (= CHE)

9.12.1 General

There are two combined heat exchangers, located in the gas machine room.

Each CHE can be used alternatively

as an LPG condenser, to condensate LPG during reliquefaction process

as a vaporizer, to produce vapour for "unloading without vapour from shore"

as a desuperheater, to desuperheat hot vapour before it is condensed in the ethylene

condenser

Description

Shell and tube heat exchanger, with gas dome and demister. Seawater flows through tubes;

cargo is on shell side.

Equipped with

local level indicator control, for vaporizing service

low temperature switch for seawater outlet (sensor within CHE tube) with alarm to

CCR

level indicator with high level switch and alarm to CCR

pressure controller with control valve for vaporizing service

pressure indicator on gas dome

low temperature switch, with sensor in shell space and alarm to CCR

9.12.2 Operating the CHE as an LPG Condenser

9.12.2.1 General

The CHE can work as an LPG condenser. The LPG will be condensed by warming up of

seawater, which is pumped through the tubes.

The CHE is designed to condensate the following media:

propylene

commercial propane

propane

ammonia

i/n-butane

butylene

1.3 butadiene

VCM

methyl chloride

ethyl chloride

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Thereby, it is possible to work with two Sulzer compressors on one LPG condenser.

Design Points

Medium Ammonia Propylene Comm. Propane

Medium inlet temperature (°C) 107 74 72

Medium outlet temperature (°C) 40 40 40

Working overpressure (bar g) 14.55 15.5 16.05

Flow weight (kg/h) 5232 13266 13476

Heat exchanged (kW) 1887 1377 1386

9.12.2.2 Starting the Condenser Process

66. Establish the suction route between tank(s) and reliquefaction group(s).

67. Adjust the pressure indicator control and the pressure switch high/low of Sulzer

compressors, which will be used, according to 3.10.1.

68. Establish the route compressor - CHE(s) - cargo receiver - with or without flash

drum - back to tank(s).

69. Establish seawater flow through the LPG condenser(s).

70. Start the Sulzer compressor(s) according to 3:10.2 and Sulzer's instructions.

9.12.2.3 Operation

71. Monitor the cargo and seawater temperatures and also the pressure indicator on heat

exchanger dome.

72. Check for incondensable gas according to 3.10.5.

73. Remove incondensable gas according to 3.10.5.3.

9.12.2.4 Stopping the Condensing Process

74. Stop the Sulzer compressors.

75. Drain the liquid from the cargo receiver and (if used) flash drum into tank.

76. Stop seawater flow through the tubes.

9.12.3 Operating the CHE as a Vaporizer

9.12.3.1 General

For the process "unloading without gas return" cargo vapour is required. This vapour can

be produced on board in the CHE working as a VAPORIZER.

The CHE shell side will be partly filled with liquid cargo. The level of liquid cargo will be

controlled by the level indicator control. The vaporizing pressure could be adjusted at the

pressure indicator control.

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The liquid will be vaporized by the heat from seawater which flows through the heat

exchanger tubes. The vapour produced flows into the tanks. Some liquid is continuously

fed into the shell side to make up for the liquid which is vaporized.

The lowest allowable seawater outlet temperature is 5 °C.

As a protection against freezing-up and malfunction, the compressors will be stopped and

the PIC and LIC will be closed by

low temperature switch on seawater outlet (1 °C)

low temperature switch in CHE shell space (2 °C)

high level switch

9.12.3.2 Starting the Vaporizing Process

77. Adjust the pressure indicator controller PIC to saturation pressure at +5 °C of the

cargo to be vaporized

i.e. propane 4.5 bar g

commercial propane 5.0 bar g

propylene 5.6 bar g

i-butane 1.0 bar g

n-butane 0.25 bar g

propane/butane mixtures see vapour diagram

butylene 0.5 bar g

ammonia 4.2 bar g

methyl chloride 2.0 bar g

78. Establish seawater flow through CHE (minimum required volume flow 100 M3 A),

then start a seawater pump (350 M3 /h), or the seawater pump of the inert gas plant,

if it is not needed for the moment.

79. Establish flow route for cargo vapour from CHE to tank.

80. Establish liquid flow into vaporizer.

81. The level control will be operated by hand or automatically. Set the hand switch of

the level control valve to position "hand operation", then open the level control valve

slowly in order to avoid refrigeration of seawater.

82. If the CHE is filled up to 60%, set the hand switch to position "automatic operation".

9.12.3.3 Operation

83. Monitor cargo and seawater temperature and CHE vaporizing pressure.

84. If the vapour production is too high, raise the set pressure of the pressure control

valve or lower the operation level of the CHE. The normal operation level in the

CHE is 650 mm above bottom.

85. Never throttle the seawater flow to control the vapour production.

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9.12.3.4 Stopping the Vaporizing Process

86. Set the hand switch of the level control valve to position "hand operation" and stop

liquid supply by closing the level control valve.

87. Continue seawater supply for some time to vaporize all liquid cargo in CHE or until

liquid from CHE has been drained.

88. Stop seawater supply.

9.12.4 Operating the CHE as a Desuperheater

9.12.4.1 General

The CHE can work as a desuperheater. The hot gas from compressor 2nd stage discharge

will be desuperheated by warming up of seawater which is pumped through the tubes.

After the desuperheater, the vapour will be led through a pipe into the ethylene condenser,

where it is condensed during vaporizing of R22.

Media to be desuperheated:

ethylene

ethane

9.12.4.2 Starting the Desuperheater Process

89. Establish vapour route - compressor 2nd stage discharge - LPG condenser - ethylene

condenser.

90. Establish seawater supply for LPG condenser(s) (approximately 400 M3 /h for one

LPG condenser).

91. Start the cascade cycle according to 3.10.3.

9.12.4.3 Operation

Monitor the cargo and seawater temperatures on the LPG condenser.

9.12.4.4 Stopping the Desuperheating Process

92. Stop the cargo compressor or open bypass ball valve (H51014 and/or H52014).

93. 2. Close ball valves H51018/51016 or H52018/52016.

94. 3.Lead ethylene gas to tank by opening V51020 and/or V52020 (mount

95. swing elbow AB 51001 and/or AB 52001 carefully).

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9.13 Cargo Heater, Cargo Cooler

9.13.1 Cargo Heater

9.13.1.1 General

The cargo heater is a shell and tube heat exchanger, designed for warming up the liquid

cargo (which is pumped through the shell side) by seawater flowing through the tubes.

It is equipped with

pressure indicator on shell side and tube side

inlet HR valve

outlet butterfly valve

drain valve

de-aerating/vacuum valve on shell side

bypass HR valve

temperature switch indicator with alarm on shell side and in cargo outlet line

flow switch indicator in seawater inlet line with alarm to the CCR

temperature control valve

Design Point

Medium ammonia propane

Medium inlet temperature (°C) -33 -42

Medium outlet temperature (°C) 0 0

Flow weight (kg/h) 100000 100000

Heat exchanged (kW) 4133 3520

Medium to be heated

ammonia

butadiene

butane

butane-propane mixtures

butylene

propylene

vinyl chloride

propane

methyl chloride

9.13.1.2 Starting the Heater Process

96. Establish the cargo route - tank - liquid line - cargo heater -CO (if

required - CO - stripping - tank) carefully (see Process Flow Diagram: Process No.

24).

97. Set selector switch in CCR to "HEATER ON".

98. Establish seawater supply for cargo heater.

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99. Throttle the butterfly valve at seawater outlet in a way that the tube side will be filled

up with seawater.

100. Adjust the temperature indicator control valve TV 07102 to the chosen temperature.

101. Open outlet valve of cargo heater (K 07003) fully and close HR valve V 07002 in

bypass.

102. Start DWPs and/or BPs.

103. Open the HR valve V 07001 at cargo heater inlet slowly to avoid refrigeration of

seawater. Regulate the flow weight of cargo under consideration of minimum

required volume flow (Chapter 3.7.7). If the cooler is filled up, open the HR valve V

07001 fully.

104. Monitor the temperature at temperature indicator control (TIC).

105. If the temperature of cargo at TIC rises too high, open the HR valve in bypass slowly

till the chosen temperature is reached.

9.13.1.3 Operation

106. Monitor the temperature and pressure indicators on shell and tube side.

107. Monitor the flow switch indicator at seawater inlet.

108. Monitor the TIC and regulate the temperature by operating the HR valve.

9.13.1.4 Stopping the Heater Process

109. Stop DWPs and/or BPs.

110. Open drain valve of cargo heater slowly to avoid refrigeration of seawater.

111. Drain the cargo to purge collector, stripping - CO and then back to tank or to shore.

112. If the cargo heater is drained, close inlet, outlet and drain valves.

113. Stop seawater supply.

114. Set selector switch in CCR to "HEATER OFF".

9.13.2 Cargo Cooler

9.13.2.1 General

The cargo cooler is a shell and tube heat exchanger to cool nonrefrigerated cargoes on shell

side by vaporizing R22 in the tubes.

It is equipped with

pressure indicator on shell side

temperature indicator at cargo outlet

inlet, outlet and drain valves

vacuum test point connection on tube side

thermostatic expansion valve (TV) for R22 injection

suction filter

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hydraulic valve GV 60604 actuated from R22 screw by pushbutton GSH 61604 or

GSH 62604

Design Point

Medium propylene oxide

Medium inlet temperature 25 °C

Medium outlet temperature 20 °C

Working overpressure 7.8 bar g

Flow weight 32880 kg/h

Heat exchanger 117 kW

Volume flow 40 M3 /h

Media to be cooled

All non-refrigerated cargoes

9.13.2.2 Starting the Cooler Process

115. Establish the cargo route - tank - liquid line - cargo cooler -stripping - tank.

116. Establish seawater supply through the R22 condenser and oil cooler.

117. Start DWPs according to 3.6.5.

118. Start R22 screw according to 3.10.6.1.

9.13.2.3 Operation

Monitor the temperature and pressure indicators on shell and tube side.

9.13.2.4 Stopping the Cooler Process

119. Close the valve V 61025 or V 62025 at R22 receiver outlet, in order to store the

charge in the receiver.

120. If the whole R22 charge is in the R22 receiver, stop the compressor - close V

08009/08010 - stop freshwater flow through the oil separator.

121. Stop the DWPs.

122. Stop seawater supply through the R22 condenser and oil cooler.

123. Drain the cargo cooler into the tank by pressurizing nitrogen into the cargo cooler

(e.g. connection for nitrogen at both liquid crossovers, H 01003, H 02003, H 03003,

H 04003).

124. Establish the route for nitrogen carefully.

125. After draining the cargo cooler, close the valve at the used nitrogen connection (H

01003, H 02003, H 03003, H 04003).

126. Close also inlet and outlet valves at the cargo cooler (H 08001, H 08002).

127. If the vessel transports the same grade on its next trip, the residual liquid stays in the

piping.

128. If the vessel changes grade, all traces of cargo have to be removed.

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9.14 Seawater Cooling System

Seawater pumps (3 x 350 M3 A) supply seawater to the heat exchangers of the gas plant.

One seawater pump (115 M3 A) supplies for inert gas plant.

Seawater pump (1 x 25 M3 A) supplies seawater to the freshwater cooler.

This system is delivered by the Yard.

Maintenance

When the pumps are stopped for an extended standstill and ambient temperatures are

sub-zero. drain heat exchangers and seawater lines on deck in order to avoid freeze-up.

9.15 Freshwater Cooling System (= FW Cycle)

(see P+I Diagram Cooling Water)

9.15.1 FW Cycle

A pump circulates freshwater through the compressors for cooling/ heating of the cargo

compressors, heating the oil in oil separators of the R22 cycles and to the bulkhead

penetrations for cooling. The cycle is also operated when the compressors are stopped and

kept ready for service. This decreases condensation of vapours in compressor cylinders

(liquid slugs) and in compressor crankcase (oil failure) as well as condensation of R22 in

oil separator. The temperature of the freshwater is automatically maintained constant.

The main components of this system are:

- 2 circulating pumps 25 M3 A, at 35 m LC

one pump as standby

with electric motors 4.6 kW, 3500 rpm

- 1 electric freshwater heater 24 kW

- 1 freshwater cooler, cooled by seawater

tube bundle length 1200 mm

shell outer diameter 273 mm

- 1 freshwater tank, with level glass and l

low level alarm

- controls for flow, temperature and pressure

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9.15.2 Starting the FW Cycle

Start cycle in good time before starting the compressors to vaporize any cargo in cargo

compressors or R22 condensate in oil separators which may have collected during

standstill.

During carriage of butane/butadiene and at low ambient temperature, there is increased

tendency to condensation. Therefore, allow more time for heating up the Sulzer

compressors.

129. Check level of freshwater tank.

130. Establish freshwater flow route.

131. Establish seawater supply to freshwater cooler by seawater pump.

132. Open all valves in freshwater cycle. . Start freshwater pump and throttle the butterfly

valve at pump discharge, so that design flow is given.

133. Throttle valves at outlets of compressors, oil separators and bulkhead penetrations

for sufficient distribution of freshwater.

134. Switch on electric heater.

135. Now, the cycle is in operation. The temperature before the compressors are

automatically maintained between 35 °C and 45 °C by the temperature control valve

(TCV 94102).

9.15.3 Stopping of Freshwater Cycle

The freshwater cycle should be stopped only for extended off-time.

136. Switch off electric heater

137. Stop freshwater pump.

138. Stop seawater supply to freshwater cooler.

9.15.4 Maintenance of Freshwater Cycle

Check regularly

level of freshwater tank (system leaks, freshwater shortage)

freshwater temperature before compressor is between +35 and +45 °C

freshwater temperature after compressor is between +35 and +45 °C

flow indicators in freshwater lines of compressors show definite flow

suction filters of freshwater pumps

The freshwater cycle contains an aqueous glycol solution with corrosion inhibitor 50%

freshwater and 50% glycol. Freezing point of the mixture approx. -36 °C. When

refilling/adding solution, re-establish correct concentration by checking with hydrometer.

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Drain seawater side of freshwater cooler at extended system standstill at sub-zero

temperatures.

9.16 Vent and Drain System

The gas plant is provided with safety relief valves, vent valves and drain valves. Piping

sections where liquid can be trapped, are fitted with relief valves for thermal expansion.

These valves are piped to the vent and drain system.

There are four vaporization pipes (B 09601, B 09602, B 09603, B 09604) in the system to

vaporize liquid from drains, relief valves or remnants after purging.

Each pipe can be connected to each vent mast. Cargoes with an atmospheric saturation

temperature above minus 105 °C can be vaporized here. The vessels are fitted with a level

high alarm/switch and drain valve.

Note: The level switch shuts off all automatic tank valves and stops cargo pumps running.

When the cargo grade has changed, the piping has to be emptied completely. Drain valves

provided at low-seated piping sections have to be connected to one of the above-mentioned

pipes in order to drain remaining liquid.

9.17 Blow-off System

(see P+I Diagram Vent + Drain)

For two-grade, the vent and drain system can be divided into two systems.

The safety relief valves of the cargo tanks are firmly piped to the vent masts; valves of

each tank to a separate vent mast.

Each vaporization pipe in the vent and drain system can be connected to each vent mast in

the same way as the vents of the reliquefaction plants.

The vent line after each tank safety relief valve is fitted with a drain plug. Open plug

occasionally (at above zero temperatures) to drain any condensate which may be present.

The same connection can be used to purge the vent line with nitrogen. Nitrogen is supplied

via hose from a nitrogen bottle.

Furthermore, a purge connection can be made from the crossover via hose to the blow-off

piping. This allows to vent displaced atmosphere to a vent mast when purging cargo tanks

or gas plant sections.

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9.18 Inert Gas Plant

The inert gas plant delivers inert gas or dry air for purging and inerting of cargo tanks,

cargo holds, process vessels and cargo piping. Cargo holds are not normally purged with

inert gas.

The capacity of the inert gas plant is 2800 Sm3/h inert gas or dry air at 0,3 bar g,

dewpoint -50 °C after expansion. Inert gas is produced by controlled combustion of gas oil

and cooling, cleaning and drying the combustion gases. Alternatively, the inert gas plant

can deliver dry air for air-purging at 0,5 bar g.

The main components of the inert gas plant are:

- air blowers

- inert gas freon dryer

- freshwater pump

- combustion chamber with cooling tower

- inert gas/air dryer

There is a supply main along deck with branches to holds and crossover. The branch to

crossovers can - via hose - be connected to liquid or vapour crossover to purge cargo tanks

or cargo plant sections. Either liquid or vapour crossover can be connected - via hose - to

the blow-off system/vent mast in order to vent the displaced volume.

Note:

If the inert gas plant is not used, open ball valve H 90 001 to avoid that cargo gas may

occur in the main engine room. Before starting the plant close the ball valve.

This valve is not included in the Simulator

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9.19 Control Air System

(see P+I Diagram Instrument Air)

The control air system supplies cleaned and dried air to:

measuring and control equipment in the gas machine room/E-room

hold spaces for topping-up

fusible plug link

deepwell pumps and instrument housings

The capacity of the control air plant is approximately 32 NM3/h dry air at 8 bar g;

dewpoint at the same pressure is -40 °C. The control air plant is installed in the main

engine room. There is a supply main along the deck with branches to consumers.

The control air plant consists of:

compressor (yard supply)

air dryer unit, which comprises the following main components:

2 pressure vessels.

2 pressure indicators

one 4/2-way valve

one distributor

one electrical switchboard

one silencer

one hygroscope

2 filters

pressure control valve

solenoid stop valve

air reservoir, 2 m' volume, dimensions: 1100 mm x 2250 mm (diameter x total

length), fitted with pressure indicator and relief valve

Additionally, the air dryer unit is equipped with a pressure switch high which stops the

unit, if the pressure rises till 7.5 bar g in times of no consumption. If the pressure in the air

reservoir drops below 5.5 bar g, the pressure switch low starts the air dryer unit.

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9.20 Nitrogen System

(see P+I Diagram Nitrogen + Methanol)

This system supplies nitrogen for the nitrogen padding at P.O. service

and for purging of cargo and vent piping.

A battery of nitrogen bottles (yard supply) - 200 bar, 50 1 volume each

- is arranged on deck. The bottles are connected to a pressure reducing station which is

equipped with two pressure control valves. The outlet pressure of the first control valve

PCV 98203 is adjustable up to 25 bar g and the second control valve PCV 98205 is

adjustable

between 0.1 and 0.7 bar g.

The following connections can be made:

Connection to each tank dome - via spool piece - to restore the nitrogen padding

above P.O. cargo during voyage

An overpressure above cargo saturation pressure should be maintained, so that the

tank pressure does not fall below 0.07 bar gauge.

Connection - from valve R 98003 - to purge gas plant equipment in the cargo

compressor room

Fixed connection to each pressure accumulator of BPs Each connection is equipped

with a pressure control valve (PCV 05205/PCV 06205) for adjusting the nitrogen

pressure in pressure accumulator always 1 bar g above suction pressure of BP.

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9.21 Hydraulic System

(see P+I Diagram Hydraulic)

The hydraulic system actuates the E.S.D. ball valves at COs, cargo tanks and in the inert

gas supply line, but also the shutoff valves in R22 injection lines on ethylene condensers

and economizers.

The hydraulic system comprises:

a hydraulic power unit, installed in the main engine room

a distribution manifold with 17 solenoid valves which allows controlling of the

E.S.D. and shutoff valves

hydraulic oil supply lines to the actuators of the E.S.D. valves (105 bar and 130 bar)

and to a.m. shutoff valves

common oil return line from the actuators to the power unit

40 3/2-way ball valves, hand-operated locally from E.S.D. valves in groups 1 - 7

The hydraulic power unit comprises the following main components:

- a storage tank, 100 1 volume

- two hydraulic oil gear pumps

supply pressure 140 bar

capacity 7 1/min (each)

with two three-phase squirrel-cage electric motors

power 2.0 kW

speed 3400 rpm/min

enclosure IP 54

- an accumulator, 20 1 volume

- 3 oil level switches, one oil level gauge, 5 pressure switches and 2 pressure gauges

- alarm box with level switches, pushbuttons, pressure switches, lamps and wiring

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9.22 Emergency Shutdown System (= E.S.D. System)

When emergency shutdown is released, the power supply to the switchboard in the E-room

and to the anticondensation heating for deck motors is disconnected. Subsequently,

- all compressors, pumps and auxiliary machines stop;

- all E.S.D. valves attain their safety position - close;

- E.S.D. alarm is released on the bridge.

Emergency shutdown can be released by:

- actuation of E.S.D. pushbuttons which are arranged at various locations on board

- melting of fusible plugs in case of fire

A pneumatic line runs along deck with fusible plugs at tank domes, in gas machine room,

at both crossovers, at purge collectors, at cargo filters, at booster pumps and at cargo

heater. In case of fire, the plug melts, the air pressure in the link decreases and the low

pressure switch PIZL 99201 initiates the shutdown.

- pressure drop in a.m. pneumatic line by loss of instrument air supply

- loss of ventilation in the E-room

Note:

After each stop of the ventilation in the E-room, the ventilation must run for approx. 10

minutes before the system can be re-started.

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9.23 Emergency Shutdown Valves (= E.S.D. Valves)

The E.S.D. valves are fitted with hydraulic actuators which open and close the valves.

Some actuators are fail-safe, spring-return type: The valves open by hydraulic pressure/oil

supply. They close by spring force when the oil pressure is released by operator, by

automatic control or by failure of the hydraulic system.

Four actuators are fail-safe, pressure-return type: The actuators do not close by spring

force. They close by hydraulic pressure from the bladder accumulator which is mounted

near the actuator.

The E.S.D. valves are divided into 7 groups:

1st tank 1 PS

2nd tank 1 SB

3rd tank 2 PS

4th tank 2 SB .

5th tank 3 PS

6th tank 3 SB

7th crossovers

Each valve of groups 1 - 7 can be actuated singly and locally (at 3-way valves), either

when this group is released from CCR, or they can be actuated remotely from CCR, when

all 3-way valves at E.S.D. valves are released locally.

The E.S.D. valves (groups 1 - 7) close automatically by emergency shutdown.

The actual closing time is max. 30 seconds (according to IMO Code).

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9.24 Methanol Injection System

(see P+I Diagram Nitrogen + Methanol)

9.24.1 Description

There is a portable unit (P 93601) with a 15 1 tank and a hand pump. This unit is used to

inject methanol into specific plant parts with a pressure below 25 bar gauge in order to

prevent or melt freeze-up. The pump is equipped with an overflow valve adjusted to 25 bar

g. Connections for methanol injection are provided at deepwell pumps and at level control

valves of CHEs, cargo receivers and flash drums.

The portable bottle can be re-charged from a methanol storage tank, installed in the cargo

compressor room. The storage tank is fitted -with filling and charging connections, with

level indicator and flame arrestor. It is filled by a hose from a road tanker.

9.24.2 Injection of Methanol

1. Stop cargo flow (compressor, pump, shutoffs).

2. Connect hose to injection plant.

3. Pressurize the pump above cargo pressure.

4. Open ball valve at injection connection.

5. Feed in methanol with hand pump.

6. Follow indication of pump discharge gauge to stop injection

immediately after component is free.

7. Avoid excess supply of methanol.

9.24.3 Maintenance

Check regularly

- level of methanol tank

- injection valves closed and not leaking

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9.25 Gas Detection System

The gas detection system checks the atmosphere in selected spaces continuously for

presence of flammable gases.

The spaces fitted with gas sampling points are shown in the sim pic MD 360

When the gas concentration at a sampling point reaches 50X of the lower flammable limit,

the gas detection unit in the cargo control room gives visible and audible alarm.

The gas detection unit is installed in the simulated cargo control room and consists of:

- a gas detector, catalytic combustion type

- a sample pump

- a multipoint selector for 8 sampling points (1 spare) with alarm unit

- sampling system with solenoid valves

- flow monitoring

- span gas bottle

On the real vessel :

(Additionally, the following portable equipment for gas detection and measuring is provided:

one gas detector, type COMIWARN 100 c, suitable for measuring the lower flammability limit of

flammable gases in air

two gas detectors, type DRAGER CH 304, including test tubes for toxic gases)

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9.26 Hold Spaces

Each cargo tank is located in a separate hold. The holds should always be kept under

overpressure.

Each hold is provided with

sample points connected to the gas detection system

connections

to dry the hold with dry air from the inert gas plant

to dry the hold with inert gas from the inert gas plant

to fill the hold with dry air from the inert gas plant

The overpressure at topping-up is controlled by pressure control valves Simulator / Real

:V22211 / PCV 30201, V21211 / PCV 20201 or V21111 / PCV 10201.

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9.27 Emergency Shut-down System/E.S.D.

System/Electrical Part

The below is for the real vsl, kept for info only:

(The E.S.D. system for interrupting operation of the gas plant in dangerous situations consist of locking,

mushroom-type pushbuttons, which are allocated at strategically important parts of the gas plant and other

parts of the ship.

The application of a pushbutton causes the cargo compressors and the deepwell and booster pumps to switch

off and all E.S.D. valves on the tanks and crossover, to close.

Emergency shut-down is also released when there is a pressure drop in the pneumatic melting fuse plug line

(see Para 3.20). The pressure of this line is controlled by the pressure switch PIZL 99201 and is alarmed

separately in the CCB (PZAL 99201).

Release of the emergency shut-down (ESD) is alarmed in the CCB and on the bridge.

One socket each, built in the junction box on starboard and portside, is arranged for the interrogation and

connection of a shore emergency shut-down system.

If there is no shore emergency shut-down system, the key switch HS 99601 is to be switched in position

"override". This position is indicated by means of a lamp "ESD override" in the CCB. Otherwise, a

connection "E.S.D. ship/E.S.D. shore" must be acquired. Afterwards, the key switch "E.S.D. shore" must be

switched in the "active" position.

Since the shore emergency shut-down system is connected to the ship's emergency shut-down system, there

is, in this case, an acoustical and optical alarm (E.S.D. ship) in the CCB and on the bridge.

Since only one socket of the ship/shore connection described above, is necessary, the socket which is not

used must be provided with a plug with built-in bridging at the respective connections.

The described plug connections are also for the transmission of the ship emergency shut-down command to

the shore system. The interrogation of the respective contacts in the CCB may only be done with intrinsically

safe circuits.

The connection ship/shore is only to be constructed with flexible cables with the respective durable

sheathing, strain-relieved, against mechanical stress.)

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10 PLANT PROCESSES AND OPERATIONS This section describes the main processes and operations but not all possible processes and

operations. The main process routes are shown on process flow diagrams (Process Nos.

1 - 27).

The descriptions apply to ONE and TWO-GRADE service.

Additionally, the following instructions should be considered:

Instructions in

DESCRIPTION OF PLANT COMPONENT AND SYSTEMS Section 3

Instructions of manufacturers Instructions Part

PLANT SEGREGATION AND SPOOL PIECES Section 5

ONE or TWO-GRADE SERVICE Section 5

SPECIAL REQUIREMENTS FOR PROPYLENE OXIDE Section 6

SPECIAL REQUIREMENTS FOR OTHER PRODUCTS Section 7

10.1 Cleaning the Gas Plant

139. After the gas plant has been assembled and pressure-tested, after repairs and

maintenance involving dismantling of pipework and components, the plant

components and piping must be thoroughly cleaned to remove residual water and

foreign matter.

140. Open drain valves and plugs provided on equipment and pipings.

141. Pass compressed air or inert, gas through piping and equipment.

Use only clean air, filtered and oilfree, from inert gas plant, control air plant or from

shore.

Divide piping into suitable sections to obtain define flow at high rate. Open and close

outlet to atmosphere in intervals to blast waters and particles out of the system.

142. Do not touch the R22 systems or the freshwater cycle, which are closed systems,

ready cleaned and filled.

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10.2 Preparation of Hold Spaces

Preparation of hold spaces involves the following steps:

drying the hold spaces with dry air (or inert gas) from the inert gas plant

filling the hold spaces with dry air from the inert gas plant

topping-up with dried air from control air system

10.2.1 Drying of Hold Spaces

143. Establish flow of dry air from inert gas plant through cargo hold.

144. Watch hold pressure. Keep one outlet valve at each hold fully open to avoid

excessive pressurization of the hold.

145. Check dewpoint of air at sample connection of outlet piping.

146. When dewpoint is acceptable, stop air supply to the hold and close valves at inlet and

outlet of hold.

It is recommended to dry the holds to a dewpoint of minus 20 °C, for ethylene

transport to minus 30 °C or lower.

10.2.2 Topping of Cargo Holds

When the cargo tanks contain cargo, the cargo holds should be maintained under

overpressure with dry air from the control air system.

147. Establish dry air flow from the control air system to cargo holds (see P+I: Air

Supply).

148. Adjust the pressure control valves PCV 10201, PCV 20201, or PCV 30201 to 10 - 30

mbar g for topping-up the cargo holds.

149. Monitor the hold pressure during voyage.

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10.3 Purging - General

10.3.1 General

Purging describes processes, where one gas (= purge gas) is fed into the gas plant to

displace another gas (for drying with air = same gas) from the gas plant. Some general

considerations, valid to several or all kinds of purging processes, are described hereunder.

Purging tanks in series or in parallel

Tanks can be connected in series or in parallel for drying and inerting. Connecting tanks in

series can result into lower consumption of purge gas. However, the process time can be

somewhat longer. than for purging of tanks in parallel. The different arrangements in

Process Diagrams (tanks in series and tanks in parallel) are given as an example only.

Purging tanks and other plant parts

The following descriptions and respective process diagrams describe the purging of the

cargo tanks and associated piping. Additionally, all other cargo plant components and

cargo piping sections have to be purged properly. These plant parts can be purged in

parallel to tank purging. Therefore, modify the described flow route or allow a partial flow

through other plant parts. Mark up a process diagram to ensure that all plant parts are

considered.

Purging tank connections

Close/throttle the flow through tank purge lines and allow for some time flow through

other tank connections.

Purging other plant parts

Provide flow - as far as possible – through

stripping crossover

dead ends of crossovers and piping sections

booster pump

cargo heater

reliquefaction plant

Open control valve(s) by hand.

When purging with air to inert gas/nitrogen or vice-versa, the displaced gas can be vented

from vents, drains or open connections to atmosphere in order to purge trapped ends and to

obtain definite flow.

The purging effect, especially at process vessels, can be improved by the folowing method:

stop gas outlet and allow pressure build-up to 0.5 bar g. Then open the outlet valve

instantaneously.

Test samples of the tank atmosphere can be taken from the sample.tubes of the cargo tanks.

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10.3.2 Alternatives for Drying and Inerting the Gas Plant

150. Product to be loaded: LPG

Dry air from the inert gas plant is passed through the cargo tanks, process vessels and

cargo piping to dry these components.

After drying with air, the gas plant must be inerted. Therefore, inert gas from the

inert gas plant is passed through the gas plant.

Alternatively, inert gas may be used for a combined drying/ air-freeing process

instead of 2 separate steps (air or inert gas) as described above.

151. Product to be loaded: NH3

Inert gas, as delivered from the inert gas plant, contains about 15% CO2 This may

lead to formation of ammonium-carbonate and subsequent plant failure. Therefore,

this inert gas must not be used.

Most administrations allow introduction of gaseous ammonia into air-filled tanks

(see also Chapter 10.3.5). Therefore, an additional inerting process after drying with

air is normally not required.

If administration requires inerting, use nitrogen.

152. Use of nitrogen instead of air or inert gas

In case of special requirements by charterer, product purity or system dewpoint, use

nitrogen from shore for drying and/or inerting instead of air or inert gas from the

inert gas plant.

153. Purging with product vapour

The direction of purge gas flow should follow gravity flow and is therefore different

for "light" gases (NH3) and "heavy" gases (e.g. LPG, ethylene). There are separate

process diagrams for both flow routes.

10.3.3 Drying with Dry Air from the Inert Gas Plant

Dry air form the inert gas plant is passed through the cargo tanks, process vessels and

cargo piping to dry all components of the cargo system. Alternatively, inert gas from the

inert gas plant or nitrogen from shore can be used.

154. Establish air flow route according to Process Flow Diagrams (Process No. 1 or 2).

155. Start inert gas plant to supply dry air.

156. Modify above route in order to dry piping and components which are not included in

above flow route according to instructions: Purging - General.

157. When target dewpoint is reached, stop dry air supply.

The inert gas plant supplies dry air with dewpoint -50 °C after expansion. If a lower

dewpoint is required, use nitrogen from shore instead of inert gas.

158. Repeat the dewpoint measurement after some hours.

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If dewpoint has not increased, the drying process is completed.

Otherwise continue drying operation.

10.3.4 Purging with Inert Gas

Inert gas from the inert gas plant is passed through the cargo tanks, process vessels and

cargo piping to displace the air from all parts of the cargo system.

Alternatively, nitrogen from shore can be used.

159. Establish inert gas flow route according to Process Flow Diagram (Process No. 3 or

4).

160. Start inert gas plant to supply inert gas.

161. Modify above route in order to inert piping and components which are not included

in above flow route according to instructions Purging - General.

162. Inerting of the tanks is completed when the oxygen content of the vented gas mixture

is below the lower flammability limit of the cargo to be loaded and within charterer's

specification.

10.3.5 Purging with Cargo Gas generated on Board

10.3.5.1 Purging with Cargo Gas generated on Board, Relative Density < 1

Liquid from shore will be vaporized in the vaporizer. The vapour is passed through cargo

tanks, cargo piping and gas crossover to the vent mast. The vapour displaces nitrogen or

inert gas from all parts of the cargo system.

163. Establish liquid/vapour flow route according to Process Flow Diagram (Process No.

5) from shore to liquid crossover - liquid line -vaporizer - to tank and from lower

purge connection gas discharge -gas crossover to vent mast.

164. Modify above route in order to purge piping and components which are not included


165. In order to purge the reliquefaction plant, operate cargo compressors for some

minutes whilst above purging operation is interrupted:

The compressor sucks gas out of the tank and discharges it back into the tank. Open

the control valves of cargo flash drum and cargo receiver by hand.

166. Purging with vapour is completed when the displaced gas content in the vented gas

mixture is within charterer's specification.

10.3.5.2 Purging of a Tank with Cargo Gas, generated on Board, Relative Density > 1, One Compressor in Service

Liquid from shore will be vaporized in the vaporizer and compressed by the compressor.

The vapour is passed through the cargo tanks, cargo piping and gas crossover to shore. The

vapour displaces nitrogen or inert gas from all parts of the cargo system.

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167. Establish liquid/vapour flow route according to Process Flow Diagram (Process No.

6) from shore to liquid crossover - stripping line -vaporizer - compressor - to

tank - gas suction - gas crossover to shore.


in above flow route according to instructions Purging -General.

169. Purging with vapour is completed when the displaced gas content in the vented gas


10.3.6 Purging with Vapour of Refrigerated Cargoes from Shore

10.3.6.1 Purging of Tanks in Parallel, Cargo Gas (NH3) from

Shore, Relative Density < 1

Product vapour from shore is passed through the cargo tanks, process vessels and cargo

piping to displace air or nitrogen from all parts of the cargo systems.

This process is valid for all purge gases which have a lower molecular weight than inert

gas or nitrogen, respectively, e.g. ammonia (for ammonia, see Chapter 4.3.2).

170. Establish vapour flow route according to Process Flow Diagram (Process No. 7)

from shore to gas crossover - gas suction - tank and from lower purge line - liquid

line - liquid crossover to shore.






the bypasses to level control valves of cargo flash drum and cargo receiver.

173. Purging with product vapour is completed when the content of inert gas/nitrogen in

the vented gas mixture is within charterer's specification.

10.3.6.2 Purging of a Tank with Vapour of Refrigerated Cargoes

to Vent Mast, Relative Density > 1

Product vapour from shore is passed through the cargo tanks, process vessels and cargo

piping to displace the inert gas/nitrogen from all parts of the cargo systems.

This process is valid for all purge gases which have a higher molecular weight than inert

gas or nitrogen, respectively, e.g. ethylene, ethane, propylene, propane, butane, butadiene,

butylene, vinyl chloride monomer, methyl chloride, ethyl chloride.

174. Establish vapour flow route according to Process Flow Diagram (Process No. 8)

from shore to liquid crossover - liquid line lower purge line of tank and from upper

purge line - gas discharge vapour crossover to vent mast.



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the bypasses to level control valves of cargo flash drum and cargo receiver.

177. Purging with product vapour is completed when the content of inert gas/nitrogen in

the vented gas mixture is within charterer's specification.

10.3.6.3 Gassing of Tanks with Liquid Ethylene from Shore by

Lower Spray Line

If shore cannot supply sufficient ethylene vapour for tank purging, it is possible to purge

the tanks by introducing liquid ethylene into the tanks by lower spray line. The liquid is

sprayed into the tank and vaporized.

Be careful by introducing the liquid into the tank.

178. Establish liquid flow route according to Process Flow Diagram (Process No. 26)

from shore to liquid crossover - stripping line -lower spray line- tank.

179. Establish vapour flow route from tank to gas discharge - vapour crossover - shore.

180. Modify above vapour flow route in order to displace the vapour to vent mast.

181. Purging is completed when the content of inert gas/nitrogen in the vented gas


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10.4 Checks before Admitting Cargo on Board

Before cargo liquid or vapour is admitted on board, check the following points:

182. Gas alarm system in operation.

183. Gas machine room and E-room ventilated.

184. Pneumatic and hydraulic system in operation.

185. Freshwater cooling system in operation.

186. The set pressures of the tank safety relief valves are correct.

187. The cargo systems including their blow-off, vent and drain systems are segregated

correctly. Each cargo system within itself is connected correctly.

188. Equipment, valves and connections of the cargo system which are not used for the

following gas process are closed or disconnected.

189. Special requirements for specific cargoes, e.g. propylene oxide, butadiene, are

considered.

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10.5 Cooling Tanks Down before Loading

IMO - Para 4.10.14

> The overall performance of the cargo containment system should be

verified for compliance with the design parameters during the initial

cool-down, loading and discharging of the cargo. Records of the

performance of the components and equipment essential to verify the

design parameters should be maintained and be available to the

Administration.<

IMO - Para 18.5.1.2

> Loading should be carried out in such a manner as to ensure that

unsatisfactory temperature gradients do not occur in any cargo tank,

piping, or other ancillary equipment.<

The cargo tanks should be cooled down to within about 15 °C of the temperature of the

cargo to be loaded.

Allowable cooling-down rate of cargo tanks:

There is no specific limitation on the rate of cooling down the cargo tank structure or on

the temperature difference between top and bottom of the tanks. It is suggested that the rate

of cooling-down should not exceed 10 °C per hour and that the temperature difference

between top and bottom should be limited to a value, which should be fixed with

classification society during first cooling-down.

Cargo tanks are cooled down by introducing liquid product into the cargo tanks via a spray

line and passing the boiloff out of the tank.

Alternative processes to cool down the cargo tanks:

If shore facilities allow, return the boiloff to shore, because this is the simplest way for the

ship. If the backpressure from shore is not too high, a little overpressure - which builds up

in the tank - is sufficient to return the boiloff vapour to the shore plant. If the backpressure

from shore is too high, use the cargo compressor to return boiloff vapour to shore. If it is

not allowed to return boiloff to shore, the boiloff is reliquefied by the ships reliquefaction

plant.

Cooling-down of gas plant components:

Shutoffs which admit very cold liquid into warm piping or vessels have to be opened

slowly and for short intervals in the beginning in order to avoid temperature shocks to the

equipment. The same applies to warm liquids (ethylene, ethane, propylene, propane,

ammonia) at higher pressure which expands into pipe sections and vessels of lower

pressure.

Disconnect electric power supply to deepwell pumps and turn deepwell pumps manually at

their coupling repeatedly during cooling-down. This helps to prevent freeze-up of the

pump and to free a pump already frozen up.

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10.5.1 Cooling-down of Cargo Tanks, with Gas-return to Shore,

with or without Compressors

190. Establish liquid product flow route according to Process Flow Diagram (Process No.

9) from liquid crossover - stripping line and spray to tank. Keep valves of

cooling-down lines and of liquid crossover still closed.

191. Establish vapour flow route: tank - upper purge line (gas suction) -(cargo

compressor - if required by backpressure from shore - see Process No. 10) - gas

crossover.

192. Open butterfly valve at liquid crossover slowly to pass liquid into the piping.

193. Open HR valve of spray lines slowly to introduce liquid into the tank.

194. Open E.S.D. valve in gas discharge slowly.

195. Start cargo compressor, if required by high vapour backpressure.

196. Observe temperature and pressure of cargo tanks.

If the temperature decreases too fast, throttle the liquid flow. If there is a

sudden drop of the temperature at tank bottom, too much liquid is introduced

into the tank.

If the temperature does not decrease fast enough, increase the liquid flow.

If the tank pressure rises too high, increase the compressor suction capacity or

throttle the liquid flow.

If the tank pressure falls too low, decrease compressor suction capacity or

throttle the gas suction line.

197. Cooling-down of the tanks is completed when the tank wall temperatures are within

about 15 °C of the temperature of the cargo to be loaded.

10.5.2 Cooling-down of Cargo Tanks, with Liquid LPG from

Shore,Gas Reliquefied

198. Establish liquid product flow route according to Process Flow Diagram (Process No.

10) from liquid crossover - stripping line and spray to tank. Keep valves of

cooling-down lines and of liquid crossover still closed.

199. Establish vapour flow route: tank - gas suction - cargo compressor

LPG condenser and further condensate flow route: LPG condenser

cargo receiver - liquid and spray line to tank.

200. Open butterfly valve at liquid crossover slowly to pass liquid into the piping.

201. Open E.S.D. valve of stripping lines fully and HR valve of spray lines slowly to

introduce liquid into the tank.

202. Operate the reliquefaction plant with "DIRECT CYCLE" (according to Chapter

3.10.2).


If temperature decreases too fast, throttle the liquid flow. If there is a sudden

drop of the temperature at tank bottom, too much liquid is introduced into the

tank.

If the temperature does not decrease fast enough, increase the liquid flow.

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If the tank pressure rises too high, increase the reliquefaction capacity or

throttle the liquid flow.

If the tank pressure falls too low, decrease reliquefaction capacity.



10.5.3 Cooling-down of Tanks, with NH3 Gas from Shore,

without Gas-return

205. Establish gas flow route according to Process Flow Diagram (Process No. 11) from

gas crossover - gas discharge - upper purge line - to tank and further route - gas

suction - reliquefaction plant (for NH3 see also Chapter 3.10) - stripping line - spray

to tank. Keep valves at crossover and tank dome still closed.

206. Open ball valve at gas crossover slowly to pass vapour into the piping.

207. Open E.S.D. valve of gas discharge lines slowly to introduce vapour into the tank.

208. Open ball valve in gas suction lines fully.

209. Operate the reliquefaction plant with "DIRECT CYCLE" (according to Chapter

3.10.2).


If temperature decreases too fast, throttle the vapour flow. If there is a sudden


tank.

If the temperature does not decrease fast enough, increase the vapour flow.

If the tank pressure rises too high, increase the reliquefaction capacity.

If the tank pressure drops too low, decrease reliquefaction capacity.



10.5.4 Cooling-down of Cargo Tanks, without Gas-return to Shore, for Ethylene/Ethane Service (Start-up)

The described process starts when the tanks are filled with superheated LEG.

212. Establish gas flow route same as in Process Diagram (Process No. 16): tank - gas

suction - compressor 1st stage - LPG condenser compressor 2nd stage -ethylene

condenser - cargo receiver and further condensate flow route: cargo receiver - cargo

flash drum - stripping line and spray to tank.

213. Open ball and E.S.D. valve in gas suction line.

214. Open E.S.D. valves at stripping and HR valves of spray lines to direct LEG back to

tank.

215. Start reliquefaction plant with "CASCADE CYCLE" (according to Chapter 13.3).

For start-up phase use only one compressor.


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If temperature decreases too fast, throttle the vapour flow. If there is a sudden


tank.

If the temperature does not decrease fast enough, increase the vapour flow.

If the tank pressure rises too high, increase the reliquefaction capacity.

If the tank pressure drops too low, decrease reliquefaction capacity.



10.6 Loading of Tanks

10.6.1 General

Liquid cargo is pumped from shore via liquid crossover and loading lines into the tanks.

The displaced vapour and the flash gas is returned to shore or reliquefied by the

reliquefaction plant.

10.6.1.1 Loading with or without Gas-return - Alternatives

If shore facilities allow, return the displaced gas to shore, because

this is the simplest way for the ship.

If it is not allowed to return gas to shore; the gas is reliquefied by theship's reliquefaction

plant.

10.6.1.2 Checks before Loading.

218. Gas alarm system in operation.

219. Gas machine and E-room ventilated.

220. Pneumatic and hydraulic system in operation.

221. Freshwater cooling system in operation.

222. The set pressures of the tank safety relief valves are correct.

223. The cargo systems including their blowoff, vent and drain systems are segregated

correctly.

224. Equipment, valves and connections of the cargo system which are not used for the

loading operation are closed or disconnected.

225. Special requirements for specific cargoes, e.g. propylene oxide, butadiene, are

considered.

226. Tanks and gas plant are purged with product gas (or nitrogen for P.O.).

227. Tanks are properly cooled down.

10.6.1.3 Checks during Loading

228. Monitor tank pressure

at undue increase of tank pressure, increase compressor capacity or

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decrease loading rate.

229. Monitor tank level

check if cargo tanks are loaded evenly or according to loading

schedule.

10.6.1.4 Checks towards End of Loading

230. Monitor pressure and level of tanks continuously. At 95% level an alarm is given.

This calls for special attention to further increase of the tank level.

231. Stop loading of the tanks immediately when the maximum allowable liquid level is

reached (98%). See Para Tank Filling Rates for maximum allowable liquid level.

232. Close the shutoff at liquid crossover somewhat before the last tank has reached its

maximum allowable liquid level. This leaves space to drain the crossover and the

liquid line into this tank.

233. The tanks are protected against becoming liquid-full by a high level switch. At 99%

level, this switch gives alarm and closes the quick-closing valves at the cargo tank

and the crossover and thus discontinues the loading process.

234. Set the selection switch for the 99% level switch to "override" in order to reopen the

quick-closing valves. The excess cargo can now be discharged with cargo pump to

another tank or back to shore. Thereafter, normal operation can be continued. Proper

handling of the loading process avoids shutdown by high level trip.

10.6.1.5 Checks at End of Loading

Adjust APRS 0.2 bar above that tank pressure at which the cargo will be transported.

10.6.2 Loading with Gas-return

235. Establish cargo flow route according to Process Flow Diagram (Process No. 12):

liquid crossover - liquid line - loading line of tank.

236. If the backpressure from shore is not too high, the displaced vapour flows to shore

without operating a cargo compressor.

Establish vapour flow route: tank - gas suction - gas crossover.

237. If the backpressure from shore is too high, use the cargo compressor to return the

displaced vapour to shore.

Establish vapour flow route: tank - gas suction - cargo compressor -gas crossover.

10.6.3 Loading without Gas-return

With this plant it is possible to load ethylene or ethane, LPG or NH3, without gas-return to

shore. The reliquefaction plant is operated with or without "CASCADE CYCLE" to cool

down the cargo and to liquefy the displaced vapour. Therefore, the loading rate depends on

the temperature of the cargo to be loaded.

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238. Establish cargo loading flow route according to Process Flow Diagram (Process No.

13): liquid crossover - liquid line - lower purge line of tank.

239. Establish vapour flow route: tank - gas suction - reliquefaction (operation with

"DIRECT CYCLE" or "CASCADE CYCLE" according to Chapter 3.10) and further

condensate flow route: cargo receiver -liquid line and lower purge line to tank.

240. Start reliquefaction plant with "DIRECT CYCLE" or "CASCADE CYCLE"

according to Chapter 3.10.

10.6.4 Loading with Cooling

241. If the saturation pressure of the cargo to be loaded is higher than the set pressure of

the tank safety relief valves, the cargo must be cooled during loading.

242. The process is the same as for "LOADING WITHOUT VAPOUR-RETURN"

(Process Flow Diagram - Process No. 13).

243. Loading with cooling requires a large cooling capacity. If all available compressors

cannot keep the tank pressure well below the set pressure of the relief valve, throttle

the loading rate.

10.6.5 Loading with Heating-up, Gas-return to Shore

244. Establish cargo flow route according to Process Flow Diagram (Process No. 14):

liquid crossover - cargo heater - liquid line and lower purge line to tank.

245. If the backpressure from shore is not too high, the displaced vapour flows to shore

without operating a cargo compressor.

Establish vapour flow route: tank - gas suction - gas crossover.

246. If the backpressure from shore is too high, use the cargo compressor to return the

displaced vapour to shore.

Establish vapour flow route: tank - gas suction - cargo compressor - gas crossover.

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10.7 Pressure Maintenance and Cooling at Sea

As required, the cargo temperature/tank pressure during transport of cargo can be

maintained constantly or decreased by operating the reliquefaction plant.

Checks during transport:

247. Monitor tank pressure

At undue increase of tank pressure operate reliquefaction plant.

248. Monitor tank level

Check even distribution of condensate on all tanks of a cargo system in order to

avoid overfilling of a single tank.

10.7.1 Reliquefaction - LPG/NH3 Service

This applies to propane, butane, ammonia, propylene, butadiene, butylene, vinyl chloride,

methyl chloride and ethyl chloride.

249. Establish flow route according to Process Flow Diagram (Process No. 15).

250. Start reliquefaction with "DIRECT CYCLE" according to Chapter 3.10.

Remark: If stripping line is not sufficient to lead condensate back to tank, use

liquid line.

10.7.2 Reliquefaction - Ethylene/Ethane Service

This applies to ethylene and ethane.


252. Start reliquefaction with "CASCADE CYCLE" according to Chapter 3.10.

10.7.3 Indirect Cooling of Non-reliquefied Cargoes

This applies to dimethylamine, monoethylamine, acetaldehyde, diethyl ether, isoprene,

isopropylamine, propylene oxide, vinyl ethyl ether, ethylene oxide/propylene oxide.

253. Establish flow route according to Process Flow Diagram (Process No. 18) and start

DWPs according to Chapter 3.6.

254. Establish flow route of R22 and start R22 cycle according to Chapter 3.10.6.

10.7.4 Heating-up during Voyage

This applies to ammonia, butadiene, butane, butane-propane mixtures, butylene, propylene,

vinyl chloride, propane.

255. Establish flow route according to Process Flow Diagram (Process No. 18) and start

DWPs according to Chapter 3.6.

256. Start heater operation according to Chapter 3.13.

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10.8 Unloading

10.8.1 General

The cargo pumps discharge the liquid from the cargo tanks to shore. The liquid volume

displaced from the tanks is replaced by vapour supplied from shore or by vapour produced

on board.

10.8.1.1 Alternative Unloading Processes

257. If available, use vapour from shore.

258. If the shore cannot supply vapour, vapour has to be produced on board in the CHE.

The CHE must not be used for cargoes below minus 50 °C (ethylene, ethane).

259. If the backpressure from shore is too high for the deepwell pumps, operate the

booster pump in series with deepwell pumps. This kind of operation is not allowed

for all non-refrigerated cargoes as well as for VCM, methyl chloride and ethyl

chloride.

260. If the shore cannot accept cold cargo, the cargo has to be warmed up in the cargo

heater during unloading.

10.8.1.2 Unloading to Low Liquid Level

The ability of the cargo pumps to operate without cavitation, especially when emptying a

tank to low level is called NPSH performance.

This performance improves

when the flow is reduced

when the tank pressure is increased above saturation pressure of the liquid = by

pressurizing the tank with vapour

The vapour for this duty can be:

supplied from shore

produced in the CHE

sucked off from the other tank by the cargo compressor.

The following steps enable pumps to unload without cavitation:

Keep tank pressure or inlet pressure as high as admitted by ample supply of vapour.

Give full attention to pump behaviour. At the end of unloading, throttle flow of

pumps to avoid cavitation. Signs of cavitation are evidenced by unsteady running of

the pump and rapid vibration of the discharge pressure gauge and ammeter dial. If

noticeable cavitation occurs, the pump has to be stopped immediately, as extended

operation with cavitation will cause pump failures.

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10.8.1.3 Unloading with Pressure from Cargo Compressor

When a deepwell pump cannot be operated, the tank can be unloaded by use of the cargo

compressor:

The cargo compressor draws vapour from shore or from another tank and pressurizes

the cargo tank (builds up an overpressure = pressure above cargo saturation

pressure).

When the overpressure is sufficient, open valve in the tank loading line. The

overpressure forces the liquid out of the tank to shore.

Alternatively, the liquid can be discharged into the booster pump which pumps the

liquid to shore.

Alternatively, the liquid can be discharged into another tank of the same cargo

system and from there unloaded with deepwell pumps.

10.8.2 Unloading with DWPs and/or BPs without Vapour from Shore

261. Establish flow route according to Process Flow Diagram (Process Nos. 19 and 20).

262. Operate deepwell pumps according to instructions.

263. Operate CHE as a vaporizer.

264. In case of insufficient tank pressure, use cargo compressor.

10.8.3 Emergency Unloading with BP, Gas transferred from Tank 2 to Tank 1


266. Operate BP and cargo compressor according to instructions.

10.8.4 Emergency Unloading with BP and CHE


268. Operate BP according to instructions.

269. In case of insufficient tank pressure, use cargo compressor under consideration of

instructions.

10.8.5 Emergency Unloading with BPs in Series, Vapour from

Shore


271. Start a compressor according to instructions.

272. The BP will be filled up with liquid by pressuring the tank with vapour.

273. Start the first BP according to instructions.

274. If the BP is at full speed, start the second BP according to instructions.

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10.8.6 Unloading with DWPs and BPs in Series and Heating-up

without Vapour from Shore

275. Establish flow route according to Process Flow Diagram (Process No. 24), but keep

discharge valve of deepwell pumps only slightly opened and keep discharge valve of

booster pump only slightly opened.

276. Operate cargo heater according to instructions in Chapter 3.13.2.

Start a deepwell pump according to instructions.

277. The deepwell pump discharges now into the booster pump.

278. As soon as the pressure gauge on BP suction side shows stable pressure, start booster

pump according to instructions.

279. If the booster pump is at full speed, open the discharge valve of the booster pump in

order to get a sufficient flow.

280. Start second deepwell pump according to instructions.

The pumps should be operated in the combination: 2 deepwell pumps + 1 booster

pump

10.9 Stripping of Cargo Tanks

10.9.1 General

The cargo pumps cannot empty the tank completely; some residual liquid remains in the

tank after unloading. This residual liquid can be discharged by pressurizing the cargo tank

and pressing the liquid out via tank stripping lines.

The tank pressure is built up with hot gas from cargo compressors.

The vapour can be taken from shore or from another tank having the same cargo.

If the vessel transports the same grade on its next trip, this residual liquid stays in the

tanks. In some cases, the tanks are maintained at low temperature during ballast voyage

with the reliquefaction plant. This requires anyhow a certain liquid level in the tanks.

If the vessel changes grade, or cargo tanks have to be prepared for inspection, all traces of

cargo, liquid or vapour, have to be removed and the tanks have to be purged.

10.9.2 Stripping of Cargo Tanks with vapour from Shore

281. Establish flow route according to Process Flow Diagram (Process No. 25), but keep

valve at tank stripping line closed.

282. Operate cargo compressor according to instructions and limitations (pressure,

temperature).

283. Pressurize cargo tank.

284. Open valve at tank stripping line to press liquid out of tank to shore.

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10.10 Draining the Crossover and Disconnecting the

Shore Connection

Before purging and disconnecting the shore connection, this has to be drained from

liquid - normally into cargo tanks.

285. Close the first valve on shore side.

286. Open valve in liquid line of cargo tank to vaporize liquid towards cargo tank.

287. Normally, the route liquid crossover to tank is left open to avoid pressure build-up in

liquid lines due to residual liquid.

288. If there is not enough pressure to drain the crossover, take inert gas from IG plant or

nitrogen from bottle battery for draining the liquid.

289. In this way, purge residuals into the tank(s).

290. When the shore connection is pressureless

close butterfly valve at crossover end

depressurize the ship/shore connection

disconnect the connection to shore

10.11 Heating-up of Tanks

10.11.1 General

Heating-up of tanks is necessary to vaporize remainings. These liquid and vaporized

remainings can amount to several tons per tank.

Use the cargo compressor for heating-up of tanks and vapour returning to shore.

Attention:

The temperature in the pipingsystem may not exceed +70 °C.

10.11.2 Heating-up of Tank

291. Establish vapour flow route according to Process Flow Diagram

(Process No. 27). .

292. Start and operate the compressor according to instructions.

293. Discharge the vaporized liquid to shore, if necessary.

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10.12 Evacuating of Tanks

After heating up the tanks by vaporizing the liquid remainings and gas return to shore,

evacuate the tanks with compressors according to Chapter 3.11 in order to avoid too high

loss of cargo gas. Therefore, an evacuation of tanks is helpful before purging them.

Evacuate the tanks to 0.5 bar g under consideration of the pressure in hold spaces.

10.13 Purging Vapour from Cargo Tanks

294. After the evacuation of tank(s) (see Chapter 3.11.3) is done, the residual vapour will

be displaced with inert gas (for NH3: dry air) from inert gas plant or with nitrogen

from shore. The gas mixture can be sent to shore, or, if allowed, to vent mast.

295. The dewpoint of the purge gas must be lower than the tank temperature in order to

avoid condensation at cold tank surfaces. Otherwise, allow the tank to warm up to

dewpoint of available purge gas.

296. See also instructions Purging - General.

10.13.1 Purging with Inert Gas to LPG/VCM/Ethylene

297. Establish vapour flow route from inert gas plant - CO - to tank via lower purge

line - liquid line - CO to vent mast (alternatively, to shore). See Process Flow

Diagram, Process No. 3.

298. Supply inert gas from inert gas plant to tank in order to displace product vapour and

to inert the gas plant.


in above route according to instructions Purging General.

300. Inerting of the tanks is completed when the product gas content of the vented gas

mixture is below the lower flammability limit and within the specification of the

charterer.

10.13.2 Purging with Dry Air to NH3

301. Establish flow route: from inert gas plant - CO - liquid line -lower purge line to tank

and via upper purge line - gas discharge - CO to vent mast (alternatively, to shore).

302. Supply dry air from inert gas plant to lower purge line of tank in order to displace

remaining product vapour.


in above route according to instructions Purging -General.

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10.14 Aerating the Cargo Tanks (= filling of the tanks

with air)

304. Before the tank can be entered (for inspection, repair, etc.), the tank atmosphere has

to be brought into a condition (gas content, oxygen level) safe for personnel.

305. Consult competent administrations and relevant regulations about the minimum

requirements for safe conditions.

306. The tanks can be aerated with dry air (dewpoint -50 °C expanded) from the inert gas

plant. The tank temperature must be higher than the dewpoint of the purge air in

order to avoid condensation from incoming air at cold tank surfaces. (This

requirement should also be considered when opening a tank to atmosphere).

307. The flow route is the same as for purging processes according to Process Flow

Diagram (Process Nos. 1 and 2):

a) Establish exhaust route from tank to vent mast.

b) Supply dry air from inert gas plant to tank.

308. Before entering tanks, a responsible officer should approve and sign a certificate that

tanks are in good order to be entered.

10.15 Aerating the Cargo Holds

Before entering cargo holds, ensure their atmosphere is safe for personnel. If cargo holds

were inerted, or if an analysis of hold atmosphere requires otherwise, the cargo holds have

to be aerated with dry air from the inert gas plant.

309. Establish air flow route from inert gas plant through cargo hold.

310. Start inert gas plant for production of dry air.

311. Check oxygen level and gas content at sample connection of outlet piping.

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11 PLANT SEGREGATION AND SPOOL PIECES The ship is a two-grade vessel, precisely: a ship for alternative service with one cargo or

two different cargoes.

Depending on the number and type (= grade) of cargoes to be transported simultaneously,

the cargo plant has to be "prepared" by setting and removing of spool pieces.

Attached Spool Piece List lists all spool pieces, their identification numbers, location and

duty.

For one-grade service there is only one cargo system.

For two-grade service two cargo systems have to be formed; each system separated from

the other, but properly connected within itself.

Two cargoes can be loaded simultaneously, because there are two crossovers.

There are segregation tables in the following sections which show the position of spool

pieces for normal cargo operation - for two-grade service. Spool pieces in Vent and Drain

System are not considered. Set spool pieces in Vent and Drain System carefully under

consideration, that each tank is firmly connected to one vent mast (see P+I: Vent and

Drain).

Additionally, if non-refrigerated cargoes are transported (not normal cargo operation),

segregate the used tank and piping from reliquefaction plant.

Thereto, the following spool pieces have to be considered:

Tank 1:AB 10003 and AS 11001/12001

Tank 2: AB 20003 and AS 21001/22001

Tank 3: AB 30003 and AS 31001/32001

Further spool pieces

AB 40001

AB 40002

AB 40003

AB 40004

AB 40005

AB 40006

Remove spool pieces, if necessary (see Process Flow Diagram).

For other processes, the setting of the spool pieces can be easily worked out by means of

the Spool Piece List and a flow sheet.

For propylene oxide, there is a separate Separation Plan for each loading case.

Set all spool pieces in a right way before loading cargo.

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11.1 One-grade Service

For one-grade service the plant has to be connected to one cargo system. In this case, plant

segregation is not required (normal cargo operation).

Exception: Transport of cargo in less than three tanks or transport of chemicals.

In case one or two tanks are not required, segregate cargo tank(s) according to two-grade

service (see chapter 5.2.5 - 5.2.7).

In case of chemical transport, disconnect deck piping and reliquefaction plant by removing

the following spool pieces:

AB 40001

AB 40002

AB 40003

AB 40004

AB 40005

AB 40006

Remark: See also Special Requirements for Propylene Oxide, Chapter 6.

11.2 Two-grade Service

For two-grade service, the plant has to be segregated into two cargo

systems. The combination of cargo systems (= plant segregation) which

can be formed, are listed below.

Item Cargo Tank

1 2 3

1. A/B A B B

2. A/B B A B

3. A/B B B A

4. A/B A B -

5. A/B B - A

6. A/B - A B

11.2.1 Setting of Spool Pieces

Cargo "A" loaded in Tank 1

Cargo "B" loaded in Tanks 2 + 3

(see Process Flow Diagram)

Tag No. Position Remark

AB 30001 ab Connecting Tank 3 to System I




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12 ANNEX 1

12.1 Instructor Pages

12.1.1 Operating Conditions

The operating condition display shows the main status of the simulator. The header and

footer as displayed in are identical for all displays. No. 6 and 7 are only displayed in the

operating condition display. No. 8 to 13 is only displayed in editors.

Snapshots are taken automatically when setting the 'snapshot interval'. Default snapshot

interval at simulation start-up is 00:00, i.e., no snapshots taken automatically. However

setting the 'snapshot interval' to 00:10 will cause snapshots to be taken at 10 minutes

intervals.

Figure 12-1. Operating conditions display

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12.1.2 Initial Conditions

The Initial Condition Directory Display is used to specify initial conditions for the training

session. The directory display is shown by pressing the Initial Condition key on the

Instructor keypad or selecting the Initial Condition button in the view section of the

Instructor displays. It contains a list of all available initial conditions, each presented with a

descriptive text. This descriptive text is typed in (entered) when an initial condition is

created. It is possible to edit this descriptive text at any time later if required.

Figure 4.1. The Initial Conditions Display

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12.1.2.1 Scenarios

A scenario is a set of pre-programmed instructor actions executed at specified times or

events during a simulator session.

Scenarios are used to store sequences of instructor actions often used during training

session. A scenario may be connected to an initial condition which may be loaded together

with the scenario. A scenario may be used many times by different instructors.

Figure 8.1. The Scenario Directory Display

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12.1.2.2 Malfunction Editor

Malfunctions are used to simulate equipment failures/ malfunctions resulting in abnormal

process conditions requiring proper actions to be taken by the trainees.

Malfunctions can be prepared, grouped and activated/ deactivated using the Malfunction

Editor.

Malfunctions can be part of a scenario for automatic execution, or they can be manually

activated. The malfunction editor can be used at any time, also during a training session.

The maximum number of malfunctions in the malfunction editor (and hence in a scenario)

is limited to 40 time trigged and 40 event trigged.

Figure 9.1. The Malfunction Editor Display

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12.1.2.3 Action Editor

Actions can be prepared, grouped and activated/deactivated using the Action Editor. Any

variable with input access within the simulation models may be controlled by the scenario

via the Action Editor.

Actions can be part of a scenario for automatic execution, or they can be activated

manually.

The editor can be used at any time, also during a training session.

The maximum number of actions in the Action editor (and hence in a scenario) is limited

to 40 time trigged and 40 event trigged (total of 80).

Figure 10.1. The Action Editor Display

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12.1.2.4 Time Editor

The Time Editor is used to adjust the scenario progression during a training session.

Entries from the action and malfunction editors are presented in a Gannt-like diagram. The

diagram shows when, in simulated time, the automatically scheduled events will occur.

The instructor can easily delay or advance the progression of any automatic action and

malfunction in the current scenario in step. However, the auto repeat malfunctions and

actions are not adjusted by the Time Editor.

Figure 11.1. The Time Editor Display

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12.1.2.5 Event Editor

The Event Editor is used to supervise, and occasionally adjust, the events and event

conditions (high/low limit and delay).

The data is presented graphically in a manner which makes it easy to spot any events or

near events.

Figure 12.1. The Event Editor Display

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12.1.2.6 Evaluation Editor

The Evaluation Editor is an aid for the instructor when evaluating the trainees’

performance. It allows for monitoring of key variables in the production plant (simulator),

thus giving an indication of how well the plant is managed/ controlled.

Figure 13.1. The Evaluation Editor Display

neptune chs lpg user manual · 2018-10-30 · kongsberg maritime doc.no.: so-1407-c / 26-oct-10...

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