MEETING ADNOC’S CO & SO 2 EMISSION LIMITS - AT WHAT COST? CASE STUDY GASCO: Mr. Dheeraj Nagwani Middle East Sulphur Plant Senior Process Engineer Operations Network 2017 October 16 th , 2017
SUMMARY OF CONTENT Introduction & Facilities Description CO Emission SO 2 Emission Conclusion
INTRODUCTION > As per ADNOC COP, emission limits from SRU stack are restricted to: Sulphur dioxide (SO 2 ) : 2000 mg/Nm3 (700 ppmv) carbon monoxide (CO) : 500 mg/Nm3 (400 ppmv) > To check compliance, GASCO conducted a study for Habshan Complex SRUs to: Identify current CO and SO 2 emission levels Evaluate possible options/solutions with cost estimate to meet the ADNOC CoP emission requirements
FACILITIES DESCRIPTION Habshan-5 Habshan-0 Habshan-1 Habshan-2 OAG U-550/551/552/553 U-50/51 U-52/53/54/57 U-58/59 U-152/153 3 Stage Claus CBA Process SUPERCLAUS Amine Based TGTU CBA Process Capacity: 600 Capacity: Capacity: Capacity: Capacity: TPD/Unit 400TPD/Unit 800TPD/Unit 740TPD/Unit 1300TPD/Unit (U-57 : 640 TPD) SRE: 97.5% SRE: 99% SRE: 99% SRE: 99.9% SRE: 98.8% TOTAL CAPACITY 11500 TPD Sulphur
CO EMISSIONS Investigating current CO emission levels An evaluation of the CO destruction in eight SRU incinerators and related > stacks were conducted to investigate the current CO emission from Habshan SRUs The comprehensive “Incinerator on Site Field Testing” for all the units were > performed The incinerators were tested at various temperatures >
CO EMISSIONS U-52/53/54/57 U 52/53/54/57 Incinerator Temperature and CO Concentration at 3mol% O 2 (dry) ˃ At ~700°C, the CO CO concentration at 3mol% O2 (ppmv DRY) 3200 2950 concentration is still more 2800 than 100 ppm higher than the ADNOC limit of 400 2400 ppmv 2000 1552 1600 1325 ˃ It is expected that ADNOC 1060 1200 880 CO limit can be achieved at 665 800 above 725°C incinerator 517 ADNOC LIMIT: 400 ppmv 400 operating temperature 0 620 640 660 680 700 720 Incinerator Temperature (°C)
CO EMISSIONS U-52/53/54/57 U 58/59Incinerator Temperature and CO Concentration at 3mol% O 2 (dry) 2800 ˃ CO concentration at 3mol% O2 (ppmv DRY) At ~690°C, the CO 2535 concentration is exactly 2400 2221 same as ADNOC limit of 2027 1981 400 ppmv 2000 1600 1428 1245 ˃ At ~710°C, CO emission 1200 from U-58/59 will be well below the 400 ppmv limit 800 652 ADNOC LIMIT: 400 ppmv 286 400 0 600 620 640 660 680 700 720 Incinerator Temperature (°C)
CO EMISSIONS U-152/153 U 152/153 Incinerator Temperature and CO Concentration at 3mol% O2 (dry) CO concentration at 3mol% O2 (ppmv DRY) 2800 ˃ At ~685°C, the CO 2558 2481 concentration is exactly 2400 2099 same as ADNOC limit of 2000 400 ppmv 1682 1600 1200 ˃ At ~700°C, CO emission from U-152/153 will be well 800 587 below the 400 ppmv limit 469 ADNOC LIMIT: 400 ppmv 273 266 400 0 630 640 650 660 670 680 690 700 710 Incinerator Temperature (°C)
CO EMISSIONS Summary At 650°C, the current CO levels are in the range of 1100 to 2300 ppmv > range All existing incinerators are capable of reducing the CO emissions to > less than 400 ppmv In order to achieve the required CO emission, the incinerators must be > operated at higher temperatures as compared to current value of 650°C Required estimated incinerators Operating Temperatures are: > CBA SRUs U-52, 53, 54 and 57 : 750°C CBA SRUs U-58 and 59 : 710°C SuperClaus SRUs U-152 and 153 : 700°C
CO EMISSIONS Evaluation of various options for CO emission reduction 1. Increasing Incinerator Operating Temperature CO emission limit can be achieved at higher incinerators operating temperatures, however it will lead to increased fuel gas consumption and increased CO 2 emission At 100% volumetric capacity > Additional fuel gas required : 4.8 MMSCFD Estimated additional fuel gas cost: US$ 4.25 million per year (*) Additional CO2 emission: 105493 tons per year At current operating capacity > Additional fuel gas required : 3.35 MMSCFD Estimated additional fuel gas cost: US$ 3 million per year (*) Additional CO2 emission: 74244 tons per year (*) Fuel gas cost considered is 2.6 US$/MMBTU
CO EMISSIONS 2. Installing Hydrogenation Reactor/Catalyst Tail Gas SO 2 , S , H 2 S, SO 2 ,CO 2 H 2 S,CO 2 , H 2 CO Hydrogenation Incinerator Reactor > An alternate solution is to install additional hydrogenation catalyst reactor/bed to convert the CO in the tail gas to CO 2 > For SO 2 and elemental Sulphur (S8) the reactions are as follows: SO 2 + 3H 2 = H 2 S+ 2H 2 O & S8 + 8H 2 = 8H 2 S > CO reacts with water vapor (H 2 O) present in the tail gas to release CO 2 and H 2 : CO + H 2 O = CO 2 + H 2
CO EMISSIONS ADVANTAGES Lower temperature incinerator operation, significant reduction in fuel gas > consumption because of: a) Exothermic reactions b) Increase in H2 c) Lower CO levels (<100 ppmv), further combustion not needed DISADVANTAGES New equipment required, Very high CAPEX & additional plot space requirement > Reduced plant throughput due to pressure drop in additional equipment > ECONOMIC EVALUATION Estimated Equipment and Catalyst Cost: 14 MMUSD > Estimated total installed cost : US$ 45 million (*) > Estimated fuel gas cost saving: 11 MMUSD/year (*) > Reduction in CO2 emission: 44% > (*) Fuel gas cost considered is 2.6 US$/MMBTU. Considering all units are operating at maximum volumetric capacity. Saving numbers are reported as compared to high temperature operation option for CO reduction.
CO EMISSIONS 3. Lowering Reaction Furnace Temperature It reduces the amount of CO formed in the reaction furnace > However, acid gas at Habshan is relatively lean and contains BTEX > Minimum reaction furnace temperature of 1050°C is required to ensure proper > BTEX destruction to avoid catalyst deactivation Lowering the furnace temperature would result in BTEX breakthrough and > catalyst deactivation in Claus reactor Therefore, CO reduction by this option is not feasible >
CO EMISSIONS 4. Lowering CO2 Content in the Acid Gas CO formation in the SRU reaction furnace depends on CO2 content in acid gas. > The current CO 2 level in acid gas is approx. 45mol% > Lowering CO 2 content in acid by 20 mol% would result in CO formation reduction > by approx. 19%. However, this would not comply to ADNOC COP CO emission regulations With a 20% reduction in CO 2 , the CO levels in stack will still be at least four time > higher than ADNOC limit. Major investment is needed as Acid Gas Enrichment technology would be needed > to improve the acid gas quality. Therefore this option is not considered feasible for further evaluation >
CO EMISSIONS 5. Incinerator modification / replacement Another possible option could be incinerator modification > CFD analysis is to be carried out to determine whether it is possible to improve > mixing in incinerators via installation of checker walls or other internals Installation of internals in existing incinerators could reduce the CO emissions > Capex impact for this option might be an additional 4-5 MM Euro each for > adjustments/replacement of incinerator
SO 2 EMISSIONS Identifying design SO 2 emission levels Sulphur Recovery Units 52/53/54/57/58/59: > As per design, all the units are expected to achieve 99% Sulphur recovery Sulphur Recovery Units 152/153: > As per design, units U-152/153 are expected to achieve 99% Sulphur recovery A Sulphur Recovery efficiency of approximately 99.7% would be required > to achieve 2,000 mg/Nm3 (700 ppmv) SO2 in the stack gas Therefore, existing SRUs at Habshan are not currently designed to meet > the ADNOC CoP emissions requirements as stated above
SO 2 EMISSIONS Evaluation of various options for SO2 emission reduction Jacobs licensed B&V Licensed Sulphur Independent Sulphur Recovery Recovery Units Consultant Units 152/153: 52/53/54/57/58/59: Additional tail gas treating Amine based TGTU would Amine based Tail Gas > > > Treatment (TGTU) on the units would be required be required back end of the CBA SRU’s Either a new SCOT unit Estimated CAPEX for all > > would be required dealing with Super Claus the Units would be ~400 Single TGTU for three off-gases MMUSD > SRU’s 52/53/54 and similar Or a Consolv unit (or other There will be OPEX impact > > arrangement for the three scrubbing process) dealing of ~110MW for all the SRU’s 57/58/59 with SO2 gases from the SRUs incinerator will be required Estimated cost of a single > TGTU for 2000 MTPD of The SCOT unit dedicated > Sulphur is approx. USD 55 to one SRU train would million cost roughly 50 MM Euro Estimated schedule : 4 (total for two 100 MM Euro) > months for FEED and 24 months for EPC. Typically Plot: 65 m X 110 > m plot area.
SO 2 EMISSIONS SRU net energy balance at various SREs Sulphur Recovery Efficiency 97% 99% 99.3% 99.7% 99.9% kWh per Metric ton "S" produced +1458 +1401 +1033 +913 +853 As SRE increases, the net energy produced from a SRU decreases > As the energy consumption increases (or the net energy produced > decreases) so too increased fuel burning This will emit additional CO 2 emission, which is undesirable outcome in a > time when carbon emission reduction is among the top environment objective
Recommend
More recommend
