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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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