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PART III.

PRACTISE ON DYNAMIC SIMULATOR

I. GAS PROCESSING PLANT

II. GAS DEHYRATION UNIT

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I. GAS PROCESSING PLANT ON

DYNAMIC SIMULATOR

1. Process description

2. Simulation PFD

3. Start –

up procedure on dynamic simulator

4. Shutdown procedure on dynamic simulator

5. Malfunction exercises

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Slug catcher GPP Deethanizer

GPP Dehydration Gas Stripper

Regeneration Stabilizer

GPP Condensate Process C3/C4 Splitter

Gas chill down & Rectifier Metering for pipeline

Storage tank and pumps

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Separate condensate and Free-water from the gas at 109 BarA, 25oC

Piping type

The volume should be sufficient to receive liquid slug coming fromthe battery limit


Slug catcher (SC-01)

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Feed stock: The natural gas stream at 29oC and 109 BarA

Remove water included in the gas

Two absorber: one on-line, the other is standby The dry natural gas exits the on-line adsorber and then treated by

dehydration After filter (F-01A) for removal of adsorbent dust.


GPP Dehydration (V-06A/B)

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The absorbents will become saturated with water for 8 hours with

condition of water saturated at inlet (29oC and 109 BarA) and

need to be regenerated.

Suppose V-06A is on standby for dehydration and V-06B need to

be regenerated.


Regeneration

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Regeneration (Desorption)

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6 steps:

1. Adsorber Switch-over

2. Depressurization

3. Heating

4. Cooling

5. Pressurization

6. Standby

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a. Adsorber Switch-over

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For a short time both adsorbers are operated in parallel to:

❑ Minimize gas composition changes

❑ Minimize carry over of liquid hydrocarbons that accumulated

in inlet pipe-work during pressurization.

❑ Avoid gas flow interruption

❑ The adsorber to be regenerated is then isolated.

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b. Depressurization

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❑ The adsorber is depressurized, after isolated at both gas in

& out, from the gas pressure (109 BarA) to the regeneration

gas pressure (35 BarA).

❑ Depressurization is limited by a restriction orifice and can be

controlled by a manual control valve so as to obtain an over

all depressurization time of 30 minutes (not simulated)

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c. Heating

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❑ Heating with dry regeneration gas which originates from suction

of the compressor of Tubro-Expander Compressor (CC-01).

❑The regeneration gas (14NM3/Hr) is heated by hot oil to 230

o

C

❑ Regeration gas flow is counter-current to adsorption

❑ The progress of heating can be monitored by T indicators installed

on adsorbent bed (TI0551A/B).

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d. Cooling

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❑ The adsorbent bed is cooled with the same regeneration

gas as for heating except that the Dehydration Gas

Heater is bypassed.

❑ The adsorbent bed will be monitored by temperature

indicators.

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e. Pressurization

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❑ The adsorber is pressurized in a down flow direction

with dry product natural gas (typically 109BarA).

❑ The rate of pressurization limited by a restriction orifice and

can be controlled by a manial control valve so as to obtain

an overall pressurization time of 30 minutes (not simulated).

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f. Standby

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❑ The adsorber will be maintained at the natural gas

pressure (109BarA) using the pressurization line.

❑ During this period some of the liquid hydrocarbons in the

inlet pipe work will evaporate due to the ambient

temperature.

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The liquid and gas from the Slug Catcher Liquid Flash Drum (V-03)

are sent to the Gas Stripper (C-04) and 2nd Stage overhead Gas

Compressor (K-03).

Pressure of the Slug Catcher Liquid Flash Drum (V-03) is controlled

at 75 BarA

A purpose of sending the gas to K-03 suction: water included in the

gas stream can be removed by Dehydration Adsorber → the gas

can be compressed by the K-03 and mixed with the feed gas before

the dehydration Regeneration gas for Dehydration will not

include water any more.


GPP Condensate Process

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Around 1/3 of the dried gas (60 NM3/HR) is sent to Cold Gas/Gas

Exchanger (E-14) to be chilled down from 26oC -35oC by the cold

gas from top of Rectifier (C-05) of -42.5

o

C The Toutlet (-36oC) is rather important factor in the gas processing:

If it is higher than specific value → a recovery of liquids cannot

be obtained

If it lower→ hydrate could form at downstream


Gas chill down & Rectifier

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Another 2/3 (134NM3/HR) is sent to the Turbo Expander (CE-01), in

which the gas is expanded from 109 Bar to 33.5 Bar to result in

lower temperature as -18

o

C. In the Rectifier:

Top product: Sale gas (methane, ethane), T = -43oC

Bottom product: heavier component such as C3, C4; T = -20oC


Gas chill down & Rectifier

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Has 2 feeds:

The liquid from the Gas Stripper after heated up from 40 86 oC

in the Condensate Cross Exchange (E-04) on the 20th tray

The Rectifier bottom liquid of -23oC on top tray which includes

95 mole% of liquid and provides external reflux for distillation

Poperating = 29 BarA

T = 14 and 109 oC at the top and bottom respectively.

Cold reflux fluid is not available.

Includes total 32 valve type trays inside


GPP Deethanizer (C-01)

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The normal operation pressure: 47 BarA

Temperatures are 44 and 40oC at the top and bottom respectively.

Includes total 6 valve type trays


Gas Stripper (C-04)

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Operating pressure is controlled at 11 BarA

LPG component (C3 and C4) is separated from the feed condensate.

The top LPG vapor from the column is totally condensed at 43 oC

One Kettle type reboiler is installed at its bottom to provide reboiling

heat by hot oil at 154 oC

Condensate is stored in a float-roof tank TK-21


Stabilizer (C-02)

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Operating pressure is controlled at 16 BarA

Including total 30 valve type trays

Propane and butane are separated

The propane vapor from the column top is totally condensed at

46oC in Splitter Condenser (E-11) of air cooled type exchanger

One Kettle type reboilers are installed at its bottom (SplitterReboiler E-10) to provide reboiling heat by hot oil at 97 oC


C3/C4 Splitter (C-03)

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Three liquid pipelines are installed to transfer the liquid products

of condensate, propane and butane from the Gas Plant to a LPG

terminal.

In normal operation of the Gas Plant, the liquid products will be

transferred directly to the LPG terminal through these three

pipeline.


Metering for pipeline

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Three LPG Bullets and a condensate Day Tank in the Plant will

be used as buffer for abnormal situation of the LPG terminal.

The bullets are used also for truck loading of LPG for domestic

use.

Condensate Day Tank (TK-21) of internal floating cone roof type

with 13m diameter and 15.6m high have a capacity of 2,000 m3

which is equivalent to three days production for a condensate

transfer tanker travel.



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Stored Condensate Tranfer Pumps (P-23A/B):

30 m3/H capacity

133 m head

Driven by 30kw motor

One standby

Deliver the condensate product in the tank to the condensate

pipeline

Single stage centrifulgal pumps

The head is designed based on requirement of 8 BarA at pipeline

inlet.



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Three LPG Bullets (V-21A/B/C):

3,35 m diameter

54,61 m long horizontal vessel

Provided for liquid products storage of 540 m

3

capacity A for propane, B for butane, and C for off specification product basically

A and B can store of specification also

Mechanically these three bullets are identical

The design pressure of 17.5 Barg is equivalent of propane vapor

pressure at 50oC→ any one of them can be used as propane storage.



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2. Simulation PFD

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2. Simulation PFD

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Slug Catcher SC-01

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2. Simulation PFD

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Slug Catcher Liquid

Flash Drum V-03

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2. Simulation PFD

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GPP

Dehydration

Regeneration Adsorber Switch-over

Depressurization

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2. Simulation PFD

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Regeneration Heating

Cooling

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2. Simulation PFD

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Regeneration Pressurization

Stanby

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2. Simulation PFD

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2. Simulation PFD

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Gas chill down

& Rectifier

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2. Simulation PFD

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Gas chill down

& Rectifier

GPP D th i

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2. Simulation PFD

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GPP Deethanizer

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2. Simulation PFD

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GPP Compression

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2. Simulation PFD

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Stabilizer C-02

Splitter C-03

Th LPG B ll t (V 21A/B/C)

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Three LPG Bullets (V-21A/B/C)

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3 Start up procedure on dynamic

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3. Start –

up procedure on dynamic

simulator

Recommended sequence of operations and demonstrates the

interaction of each section of the model during startup.

Criteria:

Operator must deminstrate an understanding of the startupprocedure

Operator must follow the correct sequence

Operator must start up smoothly

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4 Shutdown procedure on dynamic

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4. Shutdown procedure on dynamic

simulator

Recommended sequence of operations for a normal shutdown

and demonstrates the interaction of each section of the model

during shutdown.

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Blockage slug catcher downstream

Compressor K-02 trip

V03 Level transmitter LT0302 drift high

FV1201 fails close

SDV1101 fails close CC01 trip

C04 gas stripper pressure transmitter PT1801B drift high

C01 transmitter LT1302 drift low

E01A Deethanizer reboiler fouling

Loss of hot oil

Electrcal power failure

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Blockage slug catcher downstream

Compressor K-02 trip

V03 Level transmitter LT0302 drift high

FV1201 fails close

SDV1101 fails close CC01 trip

C04 gas stripper pressure transmitter PT1801B drift high

C01 transmitter LT1302 drift low

E01A Deethanizer reboiler fouling

Loss of hot oil

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II. GAS DEHYRATION ON DYNAMIC SIMULATOR


2. Simulation PFD

3. Start- up and shutdown

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The Gas Dehydration consists of the following major equipment:

a. Glycol Contactor Inlet Cooler 24HH001

b. Glycol Contactor Inlet Scrubber 24VG101

c. Glycol Contactor 24VB001

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Gl l C I l C l 24HH001

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Suction Cooler 23HBI02 is a compact type exchanger. Gas sidedesign pressure and temperature is 50.5 barg/ I55oC and the

cooling medium side design pressure and temperature is I6 barg /

I55oC. Design heat duty of the exchanger is 9749 kW.

The cooling medium is taken from the closed loop circulating

system (see section 3.I2). Control of the gas exit temperature is

by modulation of a temperature control valve on the cooling

medium return line, the temperature being measured on the inlet

to the Inlet Scrubber 24VGI0I by 24TCI009.

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Gl l C t t I l t C l 24HH001

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Gas is mixed upstream of Inlet Cooler 24HH00I that has originated from: The discharge of the 2nd Stage Recompressor 23KA002 via

23EV0002

The Test Separator 20VA004 via 20EV00I0 (with 20EV00II inparallel)

The HP Separator 20VAI0I via 20EVI00I (with 20EVI002 in parallel)

The anti-surge system of the Export Compressor 26KA00I

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Gl l C t t I l t C l 24HH001

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NOTE: There are no specific Isolation Valves for the DehydrationSystem as closing all of the above valves isolates the system.

24PDTI006 measure the differential pressure across the gas side

of the cooler.

Methanol injection upstream of the Inlet Cooler is provided for the

prevention of Hydrate formation. A 2" electrically operated valve,

42HV000I, controls the flow.

Gas then enters the Inlet Scrubber 24VGI0I where any entrained

liquid is removed.

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b I l t S bb 24VG101

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b. Inlet Scrubber 24VG101

Contactor Inlet Scrubber 24VG101 is a vertical gas/liquid separatorwith a design P of 50.5 barg and a T of I55oC. The vessel has an

internal diameter of 0.99 metres with a height of 5.56 metres.

Liquids which are disengaged are returned, under control of

24LCI007 modulating a level control valve to either the inlet of the

MP Separator 20VA202 via 4" hydraulically operated shutdown valve

24EVI005 or to the 2nd Stage Recompressor via 4" hydraulically

operated shutdown valve 24EVI0I0. 4" hydraulically operated

shutdown valve 24EVI005 will open automatically on 2nd Stage

Recompressor trip.

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b I l t S bb 24VG101

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b. Inlet Scrubber 24VG101

NOTE: The level controller is pulsed to Manual Mode and 0% output

when respective EV or XV valve is closed.

The gas is then routed to the inlet of the Glycol Contactor 24VB00I or

it can be routed through a I4" Contactor Bypass line. The manual

valves on this line are interlocked to prevent the isolation valves

being closed if the bypass valve is closed. Safeguarding

Instrumentation is provided by High and Low Level trip switch

24LSTI008.

The Inlet Scrubber can be depressurised to the HP Flare via a 3"hydraulically operated blowdown valve 24BDVI00I. A restriction

orifice downstream of the blowdown valve limits the rate of

depressurisation.

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Gl l C t t 24VBOOl

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c. Glycol Contactor 24VBOOl

Glycol Contactor 24VB00I is a vertical vessel with a design pressure

of 50.5 barg and a temperature of I55oC. The vessel has an internal

diameter of 1.67 metres with a height of I0.76 metres.

A separate compartment in the base of the vessel collects any

condensate and returns it, under the control of 24LC0007

modulating a control valve, to either:

The inlet of the MP Separator 20VA202 via 4" hydraulically

operated shutdown valve 24EVI005 or to

The 2nd Stage Recompressor via 4" hydraulically operated

shutdown valve 24EVI0I0.

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Gl l C t t 24VBOOl

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NOTE: The level controller is pulsed to Manual Mode and 0%output when respective EV or XV valve is closed.

The gas rises through the packed bed where it has intimate

contact with the lean glycol from the regeneration unit supplied

via 2" hydraulically operated shutdown valve 24XV2003 located

on the dry glycol inlet line. The glycol absorbs any water from the

gas and the, now wet, glycol is returned under the control of

24LC0006 modulating a control valve, to the inlet of the Glycol

Regeneration System (See section 3.II).

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Gl l C t t 24VBOOl

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NOTE: The level controller is pulsed to Manual Mode and 0%

output when respective EV or XV valve is closed.

The dry gas exits the top of the contactor where it is monitored by

dewpoint analyser 24AT0010. A slipstream from this vapour line

is taken to supply the Glycol Regeneration System with make-up

and stripping gas via 2" hydraulically operated shutdown valve

24XV2001. The main vapour route continues to the inlet of the

Gas Export System. Safeguarding Instrumentation is provided by

Low Level trip switch 24LST0009 on the condensate side and by

High and Low Level trip switch 24LST0008 on the wet glycol side.

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Gl l C t t 24VBOOl

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Gas Blowby is prevented by 2" hydraulically operated shutdown

valve 24XV0005 located on the condensate outlet line and by 2"

hydraulically operated shutdown valve 24XV0004 located on the

wet glycol outlet line.

The Glycol Contactor can be depressurised to the HP Flare via a

2" hydraulically operated blowdown valve 24BDV0001. A

restriction orifice downstream of the blowdown valve limits the

rate of depressurisation.

A 14" lean, dry gas then passes to the suction side of the Gas

Export Compressor 27KA001.

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Cooler 24HH001

Scrubber 24VG101

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Glycol Contactor

24VB001

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Glycol RegenerationReboiler & Surge Drum

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Glycol RegenerationFilter & Glycol/Glycol HX

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GLYCOL REGENERATION PACKAGE

Flash drum

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GLYCOL REGENERATION PACKAGE

Pumps & Glycol Trim Cooler

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GLYCOL REGENERATION PACKAGEAquaStripper C

3 Start up and shutdown

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The first step of the glycol dehydration plant start-up procedure is

to drain all the water from the system

During start-up, the workers establish glycol circulation before

adding glycol to the reboiler

After the glycol dehydration unit has been started-up for about 4

hours, the sales gas dew point is checked to make sure water is

being adequately removed from the gas

The pH of the glycol can be controlled with Buffer chemicals

When the pH of glycol above 8.5, it becomes Foamy

When the pH of glycol drops below 7, it becomes Acidic

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If the solids present in the rich glycol are not removed, they

could damage the glycol pump.

More solids in the lean glycol steam indicates there are more

solids in The reboiler

The first step of the glycol dehydration plant shutdown

procedure is shutting off the heat source

If the suspended solids content in the glycol is above the 400

to 500 ppm range, the workers probably need to Change thefilters more frequently

The presence of finely divided black solids in the glycol is

often an indication of Hydrocarbon contamination

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3 Start up and shutdown

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3 Start- up and shutdown

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