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Conversion of Suncor’s South Rosevear Facility to Acid Gas Injection

Conversion of Suncor’s South Rosevear Facility to Acid Gas Injection. Jim Maddocks, P.Eng./ Mark Conacher, P.Eng./ Leroy Dixon Gas Liquids Engineering Ltd. Suncor Energy Alberta, CANADA. Conversion of Suncor’s South Rosevear Facility to AGI. Background Process Description Project Stimulus

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Conversion of Suncor’s South Rosevear Facility to Acid Gas Injection

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  1. Conversion of Suncor’s South Rosevear Facility to Acid Gas Injection Jim Maddocks, P.Eng./ Mark Conacher, P.Eng./ Leroy Dixon Gas Liquids Engineering Ltd. Suncor Energy Alberta, CANADA

  2. Conversion of Suncor’s South Rosevear Facility to AGI • Background • Process Description • Project Stimulus • Compression Design Aspects • System Design Concepts • Start-up • Acknowledgements GPAC 2007, Calgary

  3. Background • Suncor – a growing integrated energy company strategically focused on developing one of the worlds largest petroleum reserve basins – Canada’s Athabasca oil sands. • In addition Suncor owns and operates a number of conventional sour and sweet gas facilities in Alberta and British Columbia including South Rosevear near Edson. GPAC 2007, Calgary

  4. Background • The plant was originally constructed in 1979 to process 1409 e3m3/day of Beaver Hill Lake (BHL) sour natural gas. • Built to process high pressure gas with no plant compression • Sulfinol-D sweetening for H2S, CO2 and mercaptan control. • Propane refrigerant based DPCU with EG injection for hydrate control. • Originally a single train with C5+ recovery and no recycle gas compression GPAC 2007, Calgary

  5. Background • Constructed as a 3 stage conventional Claus plant to recover sulphur • Later Suncor added a low pressure inlet train for declining BHL pool and inlet compression • Added supplemental gas refrigeration process module, inlet condensate pumps, deethanizer, liquids storage, and recycle compression. GPAC 2007, Calgary

  6. Background • Amine • Gas is sweetened in a 29 tray (1.8 m dia) contactor with Sulfinol-D solution at 600 USGPM (136 m3/hr) • LP Steam used for regeneration heat • HP Steam turbine drive amine charge pumps • Refrigeration • Two process trains with a deethanizer and sour stabilizer, LPG production and C5+ liquids GPAC 2007, Calgary

  7. Background • Claus Unit: • Conventional 3 stage unit with straight-through processing and standard alumina catalyst. • Direct fired reheaters • 171 tonnes/day design, roughly 50 mole% H2S • LP Amine Flash Gas • Sweetened and used as low grade fuel for boilers and incinerator GPAC 2007, Calgary

  8. GPAC 2007, Calgary

  9. Project Stimulus • Decreasing acid gas volumes • Difficult Claus conversion and increasingly difficult to maintain reheat temperatures and recovery levels. • Plant was operating at 20% of Claus unit design throughput. • Desire to minimize emissions • Plant had declined to less than 400 e3m3/day BHL production with new CO2 rich sweet gas. GPAC 2007, Calgary

  10. Project Stimulus • Acid Gas Design parameters • Elected to seek regulatory licence for (2) 800 HP AGI compressors with a licence for 100 tonnes/day of equivalent Sulphur disposal. • Although acid gas was only 50 mole % H2S, the facility was licensed for 60 mole % to account for changing inlet composition and potential for 3rd party gas. • Each compressor was sized to handle 76 e3m3/day of acid gas. GPAC 2007, Calgary

  11. Project Stimulus • Acid Gas Design parameters • Loss of waste heat boiler and sulphur condensers meant requirement for additional steam. • Performed steam system analysis and determined incremental requirement for 25,000 pph of 50 Psig steam. • Re-worked amine charge pump turbines for maximum steam efficiency on the 400# steam. GPAC 2007, Calgary

  12. Project Basis • Injection Well • Selected Suncor’s 8-11 BHL well located 600 meters south – short pipeline minimizes possible release. • Mature gas reservoir – never produced due to water encroachment – abandoned in 1996. • 3280 meters to completion in zone. • Reviewed casing bond log, well bore parameters, and performed injectivity test to prove injection into zone GPAC 2007, Calgary

  13. Project Basis • Injection Well • Relatively low reservoir pressure at 3-4000 kPa • Excellent porosity, permeability and good containment. • Well was re-licensed and re-completed into BHL zone with excellent formation characteristics, quality, and a definable size. • Acid gas injection was estimated to take up less than 10% of the formation volume with no discernible increase in formation injection pressure over the project life. GPAC 2007, Calgary

  14. Project Basis • Injection Well • Initiated injection modelling to simulate long-term injection. • As a result of the modelling and regulatory concerns, several area production pipelines were re-licensed for 30 % and provision for fuel gas blending considered. • Simulation results indicated migration was predicted late in the project life. GPAC 2007, Calgary

  15. Compression Concepts • 4 stage reciprocating compression to achieve the required discharge pressure. • Desire to minimize hydrate concerns and eliminate need for external dehydration. • Electric drive compression for maximum flexibility, minimal capital, and high degree of reliability. • Very low suction pressure of 49-65 kPag – compressor must handle amine plant regen gas regardless of volume and composition GPAC 2007, Calgary

  16. Compression Concepts • Variable speed compression for maximum turndown and response. • Air based aftercooling to 43°C • System must appear “bumpless” to minimize upstream process upsets. • Increases in acid gas volume must be handled by the compressor prior to flaring and regulatory non-compliance. GPAC 2007, Calgary

  17. Compression Concepts • Automatic capacity control system with a combination of speed, and auto-bypassing. • Minimize suction pressure drop. • Compressor maximum speed limited to 900 RPM for long-term life and low maintenance. • Compressor min speed limited to 300 RPM by mfr. for oil handling and torque considerations. • Discharge of 6000-8000 kPag. GPAC 2007, Calgary

  18. System Design Concepts • Acid gas contained 4% hydrocarbons affecting hydrates, water removal, and ultimately system performance. • Minimal effect on system capacity – hydrate “shift” doesn’t take place. • Gas exiting the amine regenerator is water saturated as a function of temperature: • @ 49°C = 68 g/M3 • @ 35°C = 33 g/M3 GPAC 2007, Calgary

  19. System Design Concepts • Compression without dehydration would have displayed a high hydrate temperature of roughly 26°C at discharge pressures. • Lowering final stage temperature to ground temperatures of 4°C required removal of water from interstage with supplemental cooling. • Elected to use existing plant propane refrigerant to cool acid gas mixture to 15°C after 2nd stage discharge. GPAC 2007, Calgary

  20. GPAC 2007, Calgary

  21. System Design Concepts • Lowering aftercooling temperature to 15°C removed considerable condensed water and hydrocarbons and allowed for a 20°C shift in acid gas hydrate temperatures. • Cooling require small amount of methanol injection to prevent formation of hydrates though chiller. • Single propane chiller with two(2) compressors – propane operated at 10°C to prevent tube wall over-chilling – cascaded control loops for maximum control. GPAC 2007, Calgary

  22. System Design Concepts • Condensed water, hydrocarbons and a small amount of methanol are blowcased back to the plant for re-processing in the stabilizer and water handling system. • 4th stage liquids (if any) are cascaded back into the 3rd stage suction scrubber. • 3rd stage liquids cascade back into the 2nd stage scrubber. • 2nd stage liquids flow to the blowcase for pushing to the plant GPAC 2007, Calgary

  23. System Design Concepts • Any stage 1 liquids are pumped intermittently to the blowcase. • Blowcase push gas is 3rd stage warm discharge to minimize the possibility of fuel gas contamination within the compressor system. • The existing plant water flash tank was low pressure and 2 phase requiring replacement with a higher pressure 3 phase vessel so that the hydrocarbon could be sent to the Stabilizer. GPAC 2007, Calgary

  24. System Design Concepts • Dual recycle system utilizing: • Stage 1 suction pressure makeup using cool stage 2 discharge gas – no danger of hydrates or liquids JT effect • Stage 4 hot discharge gas bypass to inlet of stage 2 intercooler for intermediate pressure makeup. • Aux blower for consistent motor cooling • Fully electronic control system with PLC and operator annex for sour vapour isolation. GPAC 2007, Calgary

  25. System Design Concepts • Magnetic level gauge for “glass-less” system. • Allowed for electronic tracking of blowcase events • Redundant thermal LSH for maximum protection. • Electronically controlled oil cooling system. • Vacuum pump system for cylinder distance piece evacuation • Electronic vibration monitoring • Engineered metallurgy for maximum system integrity. GPAC 2007, Calgary

  26. System Design Concepts • Complex system of auto-isolation and bypass valves for the chiller to allow for start-up and blowdown conditions as well as being able to start a single compressor when the other compressor is on-line. • System had to appear “bump-less” to prevent pressure bumps during automation cycle. • Automated blowcase valving system for moving water back to the plant for processing. GPAC 2007, Calgary

  27. System Design Concepts • Combination inter/aftercoolers with a single variable speed fan. • Complex system of electronic louver control as well as ambient air recirculation for winter service. • Cooler control system looked at which cooling service required maximum cooling and that became the determining variable for the fan speed control loop. GPAC 2007, Calgary

  28. System Design Concepts • Provision for methanol injection into the cooler in the event of hydrates. • Ambient recirculation heater for extreme winter operation. • Provision for methanol injection into pipeline as a final safe-guard. GPAC 2007, Calgary

  29. System Design Concepts • Chiller methanol injection rate is algorithm controlled for optimization of methanol rate. • Dependant on total gas rate (function of compressor speed), intercooling temperatures, and 1st stage suction temperature. • Methanol pumps are lead/lag for auto-backup, and equipped with variable speed drive. GPAC 2007, Calgary

  30. System Design Concepts • Auto pressure-controlled flaring of acid gas from the amine regenerator during over-capacity situations or compressor/injection failure due to any conditions, i.e., line hydrate, compressor shutdown, power failure, etc. • Recording of acid gas to flare for regulatory compliance. • Algorithm controlled fuel gas addition to allow for adequate heating value and proper regulatory dispersion of SO2. GPAC 2007, Calgary

  31. System Design Concepts • Each compressor is equipped with suction and discharge ESD valves that will open automatically on start-up – also equipped with position switches. • Each compressor has auto-blowdown to ensure ESD compliance as well as auto-blowing down to a predetermined pressure level prior to start-up to reduce initial loads and torques. • Auto-pre and post purge to reduce concentration of acid gas remaining in compressor during long-term shutdowns as well as initiating a pre-maintenance purge sequence. GPAC 2007, Calgary

  32. System Design Concepts • Materials: • Compressor piping – full stainless design for maximum protection with free acid gas water. • Cooler sections – stainless steel for condensing service. • Scrubbers – stainless • Blowcase – stainless • Chiller – stainless tube and tubesheet with carbon steel refrigerant shell. GPAC 2007, Calgary

  33. System Design Concepts • Materials, cont’d: • Pipeline: select chemistry carbon steel with hardness controlled weld procedures. 3” A333 Gr 6 Sch 80 SMLS pipe • Designed and licensed to 12.1 MPa • Not piggable under normal conditions but smart pig enabled GPAC 2007, Calgary

  34. System Design Concepts • Materials, cont’d: • Valves: stainless steel in wetted service • Control valves: stainless steel • Wellhead piping: A333 Gr 6 carbon steel • Suction piping: carbon steel – hardness controlled welding. GPAC 2007, Calgary

  35. System Design Concepts • System is also equipped with an instrument fuel gas line permitted and constructed to the same specifications as the acid gas line – allowing manual switchover during line maintenance or in the event of injection line problems. • All instruments are removable and cables can be rolled up for easy wellhead access. • Injection well is wireline serviceable through the building roof. GPAC 2007, Calgary

  36. System Design Concepts • Wellhead is equipped with • pressure control valve • Redundant pressure switches for high and low pressure conditions. • Plant controlled fail-close wellhead ESD valve • Subsurface fail-close ESD valve located 50 meters below grade. • Removable building for well access GPAC 2007, Calgary

  37. Start-Up • Phased start-up due to equipment delivery issues. • Phase 1: Sour water pumps, and sour water flash tank. Commission 4160 volt electrical • Phase 2: Air testing of compression equipment and full compressor run test with fuel gas. • Phase 3: N2/He testing of acid gas compression equipment and wellhead piping. • Phase 4: LP Boiler start-up • Phase 5: Claus unit shutdown and AGI initiation GPAC 2007, Calgary

  38. Start-Up • Phase 2 • Fuel gas run test allowed for full compressor performance and controls checking without lethal environment • Able to simulate capacity variations to match process and allow for ramp testing, bypass tuning, start-up sequencing and cooler controls tuning. • Allowed for chiller commissioning on fuel gas and tuning of control loops. GPAC 2007, Calgary

  39. Start-Up • Phase 3 • Full N2/He testing of compressor piping, scrubbers, and all connections to verify integrity of connections. • Costly but necessary • Repaired numerous leaks. • Provided a superior level of integrity and operator confidence. GPAC 2007, Calgary

  40. Start-Up • Phase 4 • Brought LP steam boiler on line and allowed for several weeks of steam system performance. • Controls testing and evaluation of new LP boiler control system. • Established operator confidence in LP boiler response and performance. GPAC 2007, Calgary

  41. Start-Up • Phase 5 • Shut down Claus unit early on Monday morning at 6:30 am and sent acid gas to flare. • Initiated and tuned new fuel gas controls to flare for dispersion requirements. • Swung blinds and block-in SRU • Brought acid gas into compressors and started 1st compressor on acid gas. • Purged compressor and initiated injection into wellbore. GPAC 2007, Calgary

  42. Start-Up • Phase 5 • Injection proceeded same day as shutdown. • Injection continues at this point with minor interruptions due to controls and other upstream process upsets. • Injection pressure as per predictions. GPAC 2007, Calgary

  43. Start-Up Issues • Start-up Issues • Hydrate in compressor discharge line during fuel gas pre-test operation – presumably hydrotest water left in piping. Freed up with methanol injection. • Minor leaks from flanges • Vacuum pump failures • Tuning on aftercooler louvers proved very difficult. GPAC 2007, Calgary

  44. Start-Up Issues • Start-up Issues • Hand held radio’s transmit on same frequency as vibration sensors and caused shutdown. • Blowcase valving installed incorrectly. • Extensive tuning of compressor ramping required due to interaction of dual bypasses and shutdown conditions. • Chiller valve sequencing, by necessity, became somewhat complex. GPAC 2007, Calgary

  45. Start-Up Issues • Start-up Issues • Chiller propane vapour can condense in the return vapour line during cold ambient conditions. During winter start-up, the chiller vapour return line experiences slugging – chiller vapour re-routed to inlet of existing gas chiller. • Chiller P bounces during a switchover causing shutdown – modified to alarm condition. GPAC 2007, Calgary

  46. Start-Up Issues • Start-up Issues • Continued periodic failure of vacuum pumps – particularly during flaring situations. • Minor instrumentation and controls issues. • Remarkably uneventful GPAC 2007, Calgary

  47. Summary • Summary • Very successful injection project. • Acid gas well is performing exactly as anticipated. • Compressors are proving to be very responsive and flexible to required conditions. • Once again – the old adage – you can’t ignore the details. GPAC 2007, Calgary

  48. GPAC 2007, Calgary

  49. GPAC 2007, Calgary

  50. GPAC 2007, Calgary

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