GAS DEHYDRATION SYSTEM

Transcription

1 GAS DEHYDRATION SYSTEM High pressure and compressed gases flow to the Glycol Contactor (MAF-3110). In the Contactor, gas flows through trays, contacting the lean glycol that is flowing across the trays and down within the Contactor. The lean glycol, having a greater affinity for water than the gas, absorbs the water. The dehydrated gas flows through the Gas/Glycol Exchanger (HBG- 3120) and then supplies the fuel gas system and excess is directed to the Sales Gas Meters before flowing to 6 Departing Pipeline, KAH Liquids from the Contactor are dumped to the Water Skimmer (MBM- 2200). The Glycol Pumps, PBA-6450/6455 direct glycol through Still Column then through the tube side of the Glycol Heat Exchanger (HBG-6440/6445) and into the Glycol Separator (MBD-6460). The Glycol Separator separates the glycol and condensate. The Glycol Separator uses a pressure control valve to maintain backpressure with flash gas. The condensate is dumped to the Water Skimmer, and the glycol is dumped through the Glycol Charcoal Filter (MAJ-6470). From there glycol is directed to the Glycol Sock Filter (MAJ-6480) and into the Glycol Reboiler/Surge Tank (BBC-6410). The Glycol Re-boiler uses the Fired Component Natural Draft Burner (EAW-6420) to supply sufficient heat to strip the absorbed water, which is vented out the top of the still column as steam. The lean glycol is directed through the shell side of both Glycol/Glycol Heat Exchangers to the suction of the Glycol Pumps. Rev: 0 Date: 12/30/11 Page 1 of 8 CA 43 A

2 A. PRE-STARTUP PROCEDURES GLYCOL CONTACTOR: NOTICE: Refer to Preliminary Considerations in SECTION 3, PART A before beginning any start-up procedures. 1. Evaluate the situation and determine whether or not the Glycol Contactor should be bypassed a. Bypass the Contactor Tower if the facility is being started up and the Glycol Re-concentration System is not in service b. Bypass the Contactor Tower if the facility is being started up and approval is granted to send wet gas to the Gas/Condensate Sales Pipeline (due to extended Glycol Re-concentration System shutdown) NOTICE: The Glycol Re-concentration System should be circulating glycol through the Contactor before gas is allowed to flow through the Contactor. 2. Verify that all vent and drain valves are closed on the system components a. Glycol Contactor, MAF Verify manual control valves are aligned to correctly direct flow a. If Contactor are bypassed, verify all valves are aligned so that only inlet/outlet and bypass valves need to be opened/closed when ready for startup (Note: it may be necessary to leave the inlet valve open during bypass for dump pressure) b. Verify gas flow stream is directed through the Contactor out to Departing Pipeline 4. Verify that the liquid level controllers, pressure controllers, temperature controllers and control valves are ready for flow a. Glycol Contactor Liquid dump, LC/LCV Rev: 0 Date: 12/30/11 Page 2 of 8 CA 43 A

3 5. Reset the Contact Tower safety devices a. Verify that no safety devices are bypassed beyond those that must be bypassed for start-up (flag device as appropriate) on the MCP b. Pull the Pull to Reset Process Group relay on the MCP to bring safety systems in service c. Monitor and place safety devices in service as they clear on the Operator Interface 6. Continue Facility Start-up REFER TO: SECTION 3, PART B (step 14) GLYCOL RE-CONCENTRATION SYSTEM: WARNING: THERE ARE ALSO HEALTH HAZARDS ASSOCIATED WITH COMING INTO CONTACT WITH GLYCOL AND SOME OF THE HYDROCARBONS THAT MAY HAVE BEEN ABSORBED BY THE GLYCOL. AVOID CONTACT WITH GLYCOL AND CONSULT THE SDS FOR DETAILED INFORMATION. 7. Verify that all vent and drain valves are closed through-out system a. Glycol/Condensate Separator, MBD-6460 b. Glycol Sock Filter, MAJ-6480 c. Glycol Charcoal Filters, MAJ-6470 d. Glycol Re-boiler/Surge Tank, BBC-6410 e. Fuel Gas KO Pot, MBF-6490 f. Glycol Pumps, PBA-6450/ Verify manual valves are open or closed as necessary to correctly direct flow through the system a. Verify that the valves downstream of the Contactor Glycol outlet SDV is open b. Verify that the Glycol Separator oil dump is open to the Water Skimmer c. Verify that the flow path is open from the Glycol Separator out through the Filters and Heat Exchangers into the Glycol Re-boiler d. Verify that the Glycol Cond. Separator, gas outlet is open to the relief PCV and the Fuel Gas KO Pot e. Verify that the flow path from the Re-boiler through the Heat Exchangers and Sock Filter into the Glycol Pumps suction is open f. Verify that the flow path from Glycol Pumps discharge into the Glycol Contactor is open Rev: 0 Date: 12/30/11 Page 3 of 8 CA 43 A

4 9. Verify that the liquid level controllers, temperature controllers and control valves are ready for flow a. Glycol/Condensate Separator, MBD-6460 Oil dump, LC/LCV Glycol dump, LC/LCV Gas outlet relief, PC/PCV b. Glycol Re-boiler/Surge Tank, BBC-6410 and Fired Component, EAW-6420 Burner fuel, PC/PCV Pilot fuel, PC/PCV 10. Verify that the level in the Glycol Re-boiler is sufficient to avoid tripping the LSL WARNING: Do not overfill surge tank with glycol. Expansion of glycol as it is heated will cause the system to overflow. 11. Close the burner and pilot manual valves 12. Reset Glycol System Safety Devices and open SDV s at the Local Panel a. Verify that no safety devices are bypassed beyond those that must be bypassed for start-up (flag device as appropriate) on the MCP b. Pull the Pull to Reset Group relay at the local Glycol Panel to bring safety devices in service and open system SDVs c. Press the Open SDV tags on the Operator Interface to open the SDVs 13. Turn the Igniter/BSL to the On position. Unit will delay 25 seconds before trial for ignition 14. Slowly open the Pilot Gas block valve, gas will now be flowing to the Pilot tip 15. If start up is successful, the flame rod will sense the flame ignition and clear the BSL 16. If the Pilot does not light, close the Pilot block valve. Turn the Igniter/BSL switch to the Off position and repeat steps Rev: 0 Date: 12/30/11 Page 4 of 8 CA 43 A

5 NOTICE: Always allow 5 minutes before trying to re-ignite pilot, so that fuel gas is not allowed to accumulate in the Fire Tube section. 17. Place the BSL back in service at the Operator Interface 18. Allow the pilot to warm up for at least 5 minutes before lighting the Main Burner. The ideal pilot flame is a lazy blue flame with yellow fingers. 19. SLOWLY open the Main Fuel Gas block valve and monitor the flames inside the firetube through the observation view-port a. Ensure that the flame quality is pencil shaped and not licking against the top of the fire tubes b. If the Main Burner does not light instantly, quickly close the Main Fuel Gas block valve to prevent accumulation of gas in the firetube. Allow 5 minutes then repeat lighting process 20. Continue to monitor the bypassed safety devices and the Re-boiler as it heats up to normal operating temperature Rev: 0 Date: 12/30/11 Page 5 of 8 CA 43 A

6 B. START-UP PROCEDURES GLYCOL RE-CONCENTRATION SYSTEM: 1. Continue to monitor bypassed safety devices and reset as they come in service WARNING: Any operating parameter that is monitored by a safety device must be continuously monitored at all times while the safety device(s) are in bypass. The bypassed safety devices (indicators) must be flagged while in bypass and reset as they come in-service. REFER TO: Section 3 Part A for further details on bypassed devices. 2. Monitor Contactor glycol level and verify that the Contactor glycol dump is functioning 3. Verify glycol flow through the system by monitoring pressure differential across filters 4. Monitor the Re-boiler to verify the temperature stabilizes at normal operating range 5. Continue to monitor the glycol level in the Re-boiler to avoid tripping LSL GLYCOL CONTACTOR: 6. If the Contactor is not bypassed, continue to monitor as facility is restored to full production 7. Take the Contactor out of bypass a. SLOWLY open the inlets to Contactor WARNING: Care should be taken to start the gas flow through the Contactors slowly. Flow surges will cause glycol to exit the Contactors out the gas outlet. 8. Continue to monitor the Glycol Re-boiler System 9. If necessary, continue to bring the facility back up to full production Rev: 0 Date: 12/30/11 Page 6 of 8 CA 43 A

7 10. Once facility is at full production, and the Glycol Re-boiler System is at full operational temperature, verify there is adequate glycol level in the Re-boiler 11. Monitor the Reboiler temperature as it heats up to normal operating temperature (verify temperature controls are operational) 12. Monitor and reset any bypassed safety devices as they come inservice 13. Monitor Contactor glycol level and verify that the Contactor glycol dump is functioning 14. Verify glycol flow through the system by monitoring pressure differential across filters 15. Monitor Glycol Separator levels and verify that the dumps are functioning 16. Monitor the Reboiler to verify the temperature stabilizes at normal operating range 17. Continue to monitor the glycol level in the Reboiler to avoid tripping LSL 18. Immediately begin using the Normal Operating Procedures to continue to monitoring the system REFER TO: SECTION 5, PART I Rev: 0 Date: 12/30/11 Page 7 of 8 CA 43 A

8 C. SHUT-DOWN PROCEDURES NOTICE: Refer to Preliminary Considerations in SECTION 4, PART A before beginning any shut-down procedures. 1. If shutdown of the Gas Dehydration System will result in unapproved wet gas sales, facility shutdown may be required REFER TO: SECTION 4 (Facility Shutdown Procedure) NOTICE: Shutting down the Gas Dehydration System will result in gas sales with higher moisture content than may be allowed by contract requirements. 2. Place the Glycol Contactor in bypass a. Open the Gas bypass valve b. Close the gas outlet valve from the Contactor 3. Shut down the Glycol Reboiler 4. Monitor the system as Glycol continues to circulate and cool down a. Monitor all system levels to ensure safe operating parameters 5. Push the Pull to Reset Group relay on the local Glycol Panel to shutdown the system and close system SDVs 6. Isolate systems a. Close the manual valves on Contactor glycol inlets and outlets b. Close the manual valves on Glycol Condensate Skimmer glycol and condensate dump lines 7. Open manual vent and drain valves as necessary to vent and drain components NOTE: If it is necessary to drain glycol from the system, store the glycol in clean containers for re-use. NOTICE: If shut-down was performed as preparation for maintenance work, or if the cause of the shutdown requires corrective action/repair, continue with Lock Out/Tag Out (LO/TO) Procedures REFER TO: Fieldwood Safe Work Practices for LO/TO (Section D Chapter 5) (can be found on the Fieldwood SEMS Portal) Rev: 0 Date: 12/30/11 Page 8 of 8 CA 43 A