TGTU Hydrogenation Reactors Operations at Lower Temperature - - PowerPoint PPT Presentation

Abu Dhabi Gas Development Company Ltd. CONFIDENTIAL

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TGTU Hydrogenation Reactors Operations at Lower Temperature

Presented By: Edward Douglas

• Sr. Process Engineer

Syed Mohamid Raza Quadri Process Engineer

Abu Dhabi Gas Development Company Ltd. CONFIDENTIAL

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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 H2S, which is removed in the downstream solvent section and recycle back as acid gas to the reaction furnace.

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Tail Gas Heater 129°c Reactor Effluent Cooler Hydrogenation Reactor 235°c 285°c

49°c Incinerator Heat Recovery System Generator Package

Lean Flexorb from tank Propane Chiller M Sour water to U-0772

Propane Propane

Rich Flexsorb for Regeneration Tail Gas Trim Heater TGTU Bypass to Incinerator Start-up/ Turndown Recycle Incinerator Air Blower Tail Gas from 3rd Condensor

Tail Gas Treating Unit (TGTU)

STL

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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.

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Process Optimization

• In-house process optimization study was conducted to evaluate the performance of

TGTU Hydrogenation Reactors (R-201) operations at lower temperature on

• perating 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.

Abu Dhabi Gas Development Company Ltd. CONFIDENTIAL

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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

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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

50 100 150 200 250 300 350 400 Case 1 Case 2 Temperature (˚C)

R-201 Operations at Lower Temperature

R-201 Inlet Temperature STS Temperature

342˚C 365˚C 274˚C 260˚C

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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

20500 21000 21500 22000 22500 23000 23500 24000 24500 25000 25500 Case 1 Case 2 Steam Generation (kg/h)

E-201 LP Steam Generation

E-201 LP Steam Generation

274˚C 260˚C

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Emissions

• COS emissions increased while operating R-201 at inlet temperature of 260˚C, but

found to be within the desired emissions specification range.

5 10 15 20 25 30 Case 1 Case 2 ppm

Emissions

COS

274˚C 260˚C

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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.

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Q & A Thank You!