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MVCS Acetone

Date post: 15-Dec-2015
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Welcome to MVCS DSU System - Satpal
Transcript

Welcome toMVCS DSU System

-Satpal

System Overview

Two Stacks ( VCU A & B)

Vapor Blower Unit (A, B & C)

4 Dual Spool Berths (36, 41, 42 & 43)

2 Single Spool Berths (52 & 53)

2 Cyclohexane Berths (41B & 42B)

1 Benzene Berth (43B)

2 VAM Berths (36 & 43)

2 Acetone (36 & 37

DSU Modes of Operation

TEST Test all the alarm set points

NORMAL Vapor processing

DEPRESSURE Depressurize a pressurized vessel

Test Mode

This mode consists of the testing and calibration that standard safety practices require to be preformed within 24 hours prior to the start of loading.

Vapour Low Pressure Vapour High Pressure Vapour Low Low Pressure Vapour High High Pressure Vapour Backflow PCV valve close in 60 seconds Detonation Arrestor High High Temperature

Confirm the system power on the chosen DSU is in the “on” position and System in TEST mode.

Test Mode Cont.

Isolate PIT, PSLL, PSHH and PDIT from the process line and open the instruments to the test panel using the valves located at each device.

PRESSURE

VACUUM

TRANSMITTER

VA

PO

R L

INE

Using the test panel, supply the pressure or vacuum required at each devise to annunciate the fault on the LCP. Each device trip will be accommodated by an alarm Horn and a Yellow or Red annunciation. Yellow annunciations indicate and alarm, red annunciations indicate a shutdown.

OPEN

CLOSE

Test Mode Cont.

Set Points for all the Alarms.

PAHH ~ 1860 mmH2O

PAH = 1500 mmH2O

PAL = 140 mmH2O

PALL ~ -240 mmH2O

PDAH = 254 mmH2O

PDALL = -65 mmH2O

Test Mode Cont.

After the testing is complete, isolate tested devices from the test panel and open them to the process line.

PRESSURE

VACUUM

TRANSMITTER

CLOSE

OPEN

VA

PO

R L

INE

Test Mode Cont.

To test the DSU detonation arrestor high high temperature switch (TSHH), go to the MVCS DSU LCP and place the Detonation Arrestor temperature test switch (TSHH) to the “TEST” position. The circuit to TSHH will open and the alarm horn and red light will annunciate on the LCP. After the TSHH testing is complete, place the TSHH switch on the DSU LCP to the “NORMAL” position

TSHHTEST NORMAL

Normal Mode

Berth-Op. will coordinate the loading hose or arm hook-up to the vessel.

The Berth-Op. will now push the MVCS Enable button.

The CCR-Op. will provide an ESD permissive signal. Choose VCU A/B Primary and Secondary. HS-560

(VCU-A select) or HS-561 (VCU-B select). Three Blowers A, B & C. Choose any two A/B, B/C

or A/C. The CCR-Op. will give the signal for the MVCS to

start by activating “HS-551” VCU stacks will start and purge each stack for two

minutes. Attempts to Light Up the Pilots. Prove pilots on at

least one VCU.

Normal Mode Cont.

If the pilots on both VCUs are proven, the combustion air blowers on the secondary VCU will stop. The combustion air blowers on the 2nd and 3rd stage of the primary VCU will stop but the combustion air blower on the 1st stage will continue to operate.

If the pilots on only one VCU are proven, the combustion air blowers on the 2nd and 3rd stage of the VCU with proven pilots will stop and the combustion air blower on the 1st stage will continue to operate. The VCU with unproven pilots will go into failure mode.

Normal Mode Cont.

Clear Alarm by pressing RESET and Start MVCS VCU-A will need to be pre-heated to 650oC before

accepting vapours with normal operating temperature of 760oC.

Indication (XI-552) that the VBU/VCU has completed its start-up process.

Press Start Vapour Processing Button. PIC loop is enabled and maintains a pressure of

1100mm WC

PIC LOOP

The pressure at the inlet of the DSU skid is controlled at a set point of approximately 1100 mm W.C.

Pressure transmitter PIT-667, located upstream of the pressure control valve PCV-667 continuously monitors the system pressure and forwards this signal to pressure controller PIC-667.

PIC-667 in turn modulates PCV-667 to maintain the pressure on the vessel being loaded in an appropriate and safe operating range. If the pressure measured by PIT-667 increases then PIC-667 will start opening PCV-667 so that more vapour (increased flow) is drawn into the system. The reverse occurs on falling inlet pressure.

De-pressure Mode

Under normal loading, there will be situations when shutdowns will occur caused by high high pressure at the DSU. The De-pressure mode will allow a way of releasing this pressure into the vapour grid without venting vapour into the atmosphere.

The MVCS must be operational and the MVCS operational indication available.

PCV-667 and XV-660 are closed because of the high high pressure shutdown indication of PSHH-666.

De-pressure Mode Cont.

Pressure transmitter PIT-667 located on the up-stream side of pressure control valve PCV-667 must be 100 mm W.C. higher than pressure transmitter PIT-667 located on the downstream side of PCV-667 before this mode can be initiated.

The Berth operator will place local “Block Valve XV-660” hand switch to the “Local” position

The Berth operator will place local “Block Valve XV-660” hand switch to the “Open” position and XV-660 will open as long as the DSC and ESD permissive are available.

De-pressure Mode Cont.

The PSHH alarm will be ignored in the De-pressure mode.

If parameters 1-5 above are met, “System Mode Switch A” on B36 MVCS LCP can be placed in the De-pressure mode.

The Berth-Op will push the Vapour Processing Start button and PCV-667 will open.

De-pressure Mode Cont.

The PVC-667 valve will remain open until the pressure is relieved or a 5 minute timer is elapsed. At the end of the 5 minute time period, the PCV valve will close and the “Vapour Processing” button will have to be pushed again if De-pressurisation is not complete.

After de-pressurisation is complete, V36-XV-660 hand switch must be placed back into the “Remote” position.

Blower Speed Control

Berth Vapour Return Line pressure is measured by PIT-668 and is maintained at a set point of 260mmWC to 400mmWC. Pressure transmitter PIT-668, located down stream of MVCS DSU pressure control valve PCV-667 measures the system pressure and forwards this signal to pressure controller built inside the PLC PIC-568. PIC-568 in turn controls the two variable speed drives chosen to operate, which in turn regulates the speed of the two vapour blowers chosen to operate.

Blower Speed Control

?

THANK YOU


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