TGTU Hydrogenation Reactors Operations at Lower Temperature Presented By: Edward Douglas Sr. Process Engineer Syed Mohamid Raza Quadri Process Engineer Page 1 Abu Dhabi Gas Development Company Ltd. CONFIDENTIAL
Tail Gas Treating Unit (TGTU) • Sulphur Recovery Unit (SRU) and Tail Gas Treating Unit (TGTU) consists of 4x25% identical parallel Units (0751/0752/0753/0754) designed for Sulphur processing capacity of 3000 TPD per Train; i.e. 12,000 TPD total. • Al Hosn Gas uses TGTU to treat Claus tail gas from the upstream SRU to meet the emission specifications of 99.9% Sulphur Recovery. • Treated gas from the TGTU is combusted in the Incinerator (H-201) prior to venting to the atmosphere. TGTU consists of a hydrogenation section and a solvent section. • • The hydrogenation section reduces all sulphur compounds, including sulphur vapour to H 2 S, which is removed in the downstream solvent section and recycle back as acid gas to the reaction furnace. Page 2 Abu Dhabi Gas Development Company Ltd. CONFIDENTIAL
Tail Gas Treating Unit (TGTU) TGTU Bypass to Incinerator Start-up/ Turndown Recycle 129°c Propane Chiller Tail Gas from 3 rd Condensor 49°c 235°c Tail Gas Heater Propane Heat Recovery Incinerator System Generator Package Sour water 285°c to U-0772 Tail Gas Trim Heater Propane STL Hydrogenation Reactor Lean Flexorb from tank Rich Flexsorb for Regeneration Reactor Effluent Cooler M Incinerator Air Blower Page 3 Abu Dhabi Gas Development Company Ltd. CONFIDENTIAL
TGTU Process Description • Tail gas from third condenser (E-110) at 129˚ C is heated indirectly in Tail Gas Heater (E-211A/B) and Tail Gas Trim Heater (E-212A/B) to about 285°C (design) prior to entering the Hydrogenation Reactor (R-201) • Saturated and superheated HP steams are used in the Tail Gas Heater (0751-E- 211A/B) and the Tail Gas Trim Heater (0751-E-212A/B) respectively to raise the temperature of the Claus tail gas to a temperature that is suitable for the hydrogenation and hydrolysis reactions in the Hydrogenation Reactor (0751-R-201) • Effluent gases from hydrogenation reactor (R- 201) are cooled to 162˚C in reactor effluent cooler (E-201) generating LP Steam. Page 4 Abu Dhabi Gas Development Company Ltd. CONFIDENTIAL
Process Optimization • In-house process optimization study was conducted to evaluate the performance of TGTU Hydrogenation Reactors (R-201) operations at lower temperature on operating conditions of TGTU, looking after gains in power generation by additional energy in STS from trim heater and impact in the steam balance. Exercise was initiated after getting feedback from catalyst supplier about conversion equilibrium curves showing same remains above 90% with temperatures above 280ºC. Page 5 Abu Dhabi Gas Development Company Ltd. CONFIDENTIAL
R-201 Operations at Lower Inlet Temperature Description Case 1 Case 2 R- 201 Inlet Temperature (˚C) 274 260 STS Temperature (˚C) 342 365 E- 201 LP Steam Generation (kg/h) 25189 22139 COS (ppm) 12 25 Enthalpy of STS (kJ/kg) 3068.77 3143.41 STS Flow (kg/h) 187835 187835 Page 6 Abu Dhabi Gas Development Company Ltd. CONFIDENTIAL
R-201 Operations at Lower Inlet Temperature • Operating R-201 at reduced inlet temperature of 260˚C compared to 274˚ C • Superheated HP steam (STS) temperature increased from 342˚C to 365˚ C R-201 Operations at Lower Temperature 400 365˚C 342˚C 350 300 274˚C Temperature (˚C) 260˚C 250 200 150 100 50 0 Case 1 Case 2 R-201 Inlet Temperature STS Temperature Page 7 Abu Dhabi Gas Development Company Ltd. CONFIDENTIAL
E-201 LP Steam Generation • LP steam generation from waste heat boiler reduced from 25,189 kg/h to 22,139 kg/h which caused less LP steam export from SRU E-201 LP Steam Generation 25500 274˚C 25000 Steam Generation (kg/h) 24500 24000 23500 23000 22500 260˚C 22000 21500 21000 20500 Case 1 Case 2 E-201 LP Steam Generation Page 8 Abu Dhabi Gas Development Company Ltd. CONFIDENTIAL
Emissions • COS emissions increased while operating R- 201 at inlet temperature of 260˚C, but found to be within the desired emissions specification range. Emissions 30 260˚C 25 20 ppm 15 274˚C 10 5 0 Case 1 Case 2 COS Page 9 Abu Dhabi Gas Development Company Ltd. CONFIDENTIAL
Conclusions • Reducing the inlet temperature of hydrogenation reactor (R- 201) from 274˚C to 260˚C resulted in – Increase of superheated HP steam (STS) temperature from 342˚C to 365˚C – Decrease in LP steam generation from E-201 – Increase of power generation from steam turbines resulting in saving of 0.16 M$/annum for four SRUs in operation. – Increase in MP and LP stream generation from steam turbines resulting in additional savings. • R-201 operations at inlet temperature of 265˚ C is not creating any performance issues in TGTU in terms of environmental emissions. Page 10 Abu Dhabi Gas Development Company Ltd. CONFIDENTIAL
Q & A Thank You! Page 11 Abu Dhabi Gas Development Company Ltd. CONFIDENTIAL
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