Dow Oil, Gas & Mining

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1 Dow Oil, Gas & Mining Application of UCARSOL TM HS-103 high performance solvent for energy conservation and emission compliance in refinery Sulphur recovery tail gas treating unit (TGTU) Dow.com Yousuf Khalaf The Dow Chemical Company January 23 rd, 2017

2 OVERVIEW Challenges for modern refineries Refinery Sulphur recovery unit (SRU) SRU Claus reaction unit TGTU and incineration unit TGTU value drivers UCARSOL TM HS-103 Solvent conversion results Conclusions 2

3 POLL QUESTION In terms of Sulphur content management, what are the biggest challenges refineries face today? A) Increased variability in crude slate (heavier, more sour crude) B) Regulatory pressures (lower Sulphur content in refinery products/ reduced emissions) C) Increasing operating costs D) Aging assets 3

4 CHALLENGES FOR MODERN REFINERIES Shift towards production and processing of heavy, sour crudes - Leading to increased acid gas generation - Requiring capital intensive expansions / upgrades - Responsible for gas treating bottleneck Greater regulatory pressure for lower Sulphur levels in refinery products Increased need for technological solutions for energy efficiency improvement and operating cost reduction Reduced effluent emission is a key driver for modern refineries Current case study: TGTU solvent conversion of a China-based refinery from generic MDEA to Dow s specialty UCARSOL TM HS-103 solvent 4

5 REFINERY SULPHUR RECOVERY UNIT (SRU) Includes (i) Claus reaction unit, (ii) TGTU, and (iii) Incineration unit Claus reaction unit deals with conversion of acid gases (H 2 S rich) to Sulphur TGTU involves scrubbing of tail gas via hydrogenation and amine absorption Incineration unit ensures combustion and venting of tail gas after heat recovery 5

6 SRU CLAUS UNIT Refinery acid gas details From main amine regenerator From sour water stripping Flow rate (Nm 3 /hr) H 2 S (mol%) NH 3 (mol%) 11,200 5, Receives gas streams from main amine unit, TGTU and sour water stripper 95% H 2 S converted to Sulphur through Claus furnace and 2 stage reactors Partial conversion of H 2 S to SO 2 in furnace, along with waste heat recovery Tail gas from Claus unit (H 2 S, SO 2, CS 2, COS, Sulphur vapor) goes to TGTU 6

7 TGTU AND INCINERATION UNIT The first step involves converting most of the non-h 2 S species to H 2 S in the catalytic hydrogenation reactor followed by quenching to 40 ºC The second step involves selective H 2 S removal through a regenerative amine process (absorption and stripping) The incineration unit ensures combustion of all Sulphur species to SO 2 and other combustible gases to CO 2 and H 2 O followed by heat recovery and venting 7

8 TGTU VALUE DRIVERS After the hydrogenation reactor, the tail gas contains about 1-2 mol% H 2 S The acid gases in the tail gas are reversibly captured by the amine in an absorber and removed in a stripper to enable the lean amine recirculation The overall efficiency of a TGTU is dependent on the amine s H 2 S selectivity A better H 2 S selectivity will enable improved treated gas specification, higher productivity (solvent flow rate), energy savings (steam consumption) and reduced incineration load and regulatory emission compliance 8

9 UCARSOL TM HS-103 UCARSOL TM HS-103 is an industry leading high performance gas treating solvent from Dow Higher H 2 S selectivity as compared to selective generic amine solvents (MDEA) Specially formulated to achieve improved performance (low H 2 S) in the demanding low pressure conditions of TGTUs Solvent conversion typically involves a technical evaluation of the TGTU using proprietary simulator and performance benchmarking Value proposition includes environmental regulation compliance, energy savings, reduced solvent loss, increased gas treating capacity with existing facilities Product is supported by AMINE MANAGEMENT SM Program (AMP) of Dow Oil, Gas & Mining Properties of 50 wt% UCARSOL TM HS-103 solvent Property Value Boiling Point, º C (760 mmhg) Freezing Point, º C Solubility in Water at 20 ºC Complete Density, at 40 ºC, kg/l Viscosity, at 40 ºC, cp 5.0 9

10 SOLVENT CONVERSION RESULTS Feed tail gas With generic MDEA (30 wt%) With UCARSOL TM HS-103 (50 wt%) Flow rate (Nm 3 /hr) (Dry) Composition (mol%) CO 2 H 2 S Circulation flow rate (m 3 /hr) Regenerator steam consumption (mt/hr) Treated gas H 2 S content (ppmv) Circulation flow rate m 3 /hr Regenerator steam consumption (mt/hr) Treated gas H 2 S content (ppmv) 36, The refinery successfully upgraded their TGTU solvent in early 2013 A validation performance test was conducted towards end of 2013 With the conversion from generic MDEA to UCARSOL TM HS-103 solvent, the refinery was able to achieve: 40% reduction in solvent circulation flow rate 30% energy savings through reduced stream consumption 80% improvement in treated gas H 2 S specification Emission norm of 200 mg/nm3 SO 2 (40% reduction) in exhaust 10

11 CONCLUSION A China based refinery TGTU was successfully converted from generic MDEA solvent to Dow s specialty UCARSOL TM HS-103 solvent After the conversion, the unit was able to: Maintain a higher solvent strength leading to a lower circulation rate Achieve 30% energy savings Deliver a 20 ppmv H 2 S specification in the treated gas Accomplish 40% reduction in SO 2 emission All these operational benefits were realized without any equipment modification or solvent loss in the unit 11

12 Thank You Trademark of The Dow Chemical Company ( Dow ) or an affiliated company of Dow SM Service mark of The Dow Chemical Company