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Application of UCARSOLTM HS-103 high

performance solvent for energy conservation and

emission compliance in refinery Sulphur recovery

tail gas treating unit (TGTU)

Yousuf Khalaf

The Dow Chemical Company

January 23rd, 2017

OVERVIEW

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• Challenges for modern refineries

• Refinery Sulphur recovery unit (SRU)

• SRU Claus reaction unit

• TGTU and incineration unit

• TGTU value drivers

• UCARSOLTM HS-103

• Solvent conversion results

• Conclusions

POLL QUESTION

In terms of Sulphur content management, what are

the biggest challenges refineries face today?

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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

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

UCARSOLTM HS-103 solvent

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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 (H2S 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

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SRU CLAUS UNIT

• Receives gas streams from main amine unit, TGTU and sour water stripper

• 95% H2S converted to Sulphur through Claus furnace and 2 stage reactors

• Partial conversion of H2S to SO2 in furnace, along with waste heat recovery

• Tail gas from Claus unit (H2S, SO2, CS2, COS, Sulphur vapor) goes to TGTU

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From mainamine

regenerator

From sour water

stripping

Flow rate (Nm3/hr)

11,200 5,900

H2S (mol%)

85 36

NH3

(mol%)- 36

Refinery acid gas details

TGTU AND INCINERATION UNIT

• The first step involves converting most of the non-H2S species to H2S in the

catalytic hydrogenation reactor followed by quenching to 40 ºC

• The second step involves selective H2S removal through a regenerative amine

process (absorption and stripping)

• The incineration unit ensures combustion of all Sulphur species to SO2 and other

combustible gases to CO2 and H2O followed by heat recovery and venting

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TGTU VALUE DRIVERS

• After the hydrogenation

reactor, the tail gas contains

about 1-2 mol% H2S

• 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 H2S selectivity

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• A better H2S selectivity will enable improved treated gas specification, higher

productivity (solvent flow rate), energy savings (steam consumption) and

reduced incineration load and regulatory emission compliance

UCARSOLTM HS-103

• UCARSOLTM HS-103 is an industry leading high

performance gas treating solvent from Dow

• Higher H2S selectivity as compared to selective

generic amine solvents (MDEA)

• Specially formulated to achieve improved

performance (low H2S) 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

MANAGEMENTSM Program (AMP) of Dow Oil,

Gas & Mining

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Property Value

Boiling Point, º C （760 mmHg） 104.0

Freezing Point, º C - 22.0

Solubility in Water at 20 ºC Complete

Density, at 40 ºC, kg/L 1.0519

Viscosity, at 40 ºC, cP 5.0

Properties of 50 wt% UCARSOLTM HS-103

solvent

SOLVENT CONVERSION RESULTS

• 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 UCARSOLTM 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 H2S specification

‒ Emission norm of 200 mg/Nm3 SO2 (40% reduction) in exhaust

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Feed tail gas With generic MDEA (30 wt%) With UCARSOLTM HS-103 (50 wt%)

Flow rate (Nm3/hr)

(Dry)

Composition (mol%)

Circulation flow rate (m3/hr)

Regeneratorsteam

consumption (mT/hr)

Treated gas H2S content (ppmv)

Circulation flow rate

m3/hr

Regeneratorsteam

consumption (mT/hr)

Treated gas H2S content (ppmv)

CO2 H2S

36,320 4.5 1.7 250 28 125 150 20 20

CONCLUSION

• A China based refinery TGTU was successfully converted from generic

MDEA solvent to Dow’s specialty UCARSOLTM 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 H2S specification in the treated gas

‒ Accomplish 40% reduction in SO2 emission

• All these operational benefits were realized without any equipment

modification or solvent loss in the unit

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ThankYou

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