Acid Gas Removal Unit (AGRU)
Process Description
Acid gas removal processes utilize amines or specialty solvents to remove acid gases such as H2S and/or CO2 from Refinery Fuel Gas (RFG) in order to meet the gas quality specifications. The sour gas is contacted with lean amine in the contactor tower. An acid-base reaction occurs, binding the acid gases to the amine with a weak bond. The rich amine then flows to a regenerator, where heat breaks the weak bond between the amine and the acid gas, releasing the acid gas and regenerating the amine for re-use.
The acid gases exit the top of the regenerator for further treatment while the lean amine is recirculated back to the contactor in a recirculating loop. Liquid amine treating can also be used to remove H2S from Liquid Petroleum Gas (LPG). In this case a liquid-liquid contactor is used to contact the lean amine with the liquid LPG.
Refinery Needs
- Achieve oil production quotas via reliable treatment of acid gases that otherwise bottleneck unit operations
- Provide consistent fuel gas quality to ensure reliability of all burner operations across the refinery
- Minimize refinery off gas emissions through effective acid contaminant removal from the RFG
Production Challenge/Pall Solution
Challenge
Reduced refinery shipments due to AGRU operational issues curtailing gasoline, jet fuel and diesel production
Solution
Improve refinery productivity and reliability with consistent RFG quality by controlling AGRU foaming and fouling via effective liquids and solids removal upstream of the contactor to protect the amine loop.
KO pots, mesh pads, cyclonic devices and conventional filter-separators may not effectively remove aerosol-sized liquid hydrocarbon droplets or fine solids.
remove aerosol-sized liquid hydrocarbon droplets or fine solids.
High efficiency SepraSol™ Plus liquid/gas coalescers and Medallion™ HP liquid/gas coalescers
provide 99.999% removal at 0.3 microns per the DOP test and 1 ppb downstream per the modified ANSI/CAGI-400-1999 test procedure. Both provide excellent foaming protection.
High efficiency coalescers can also be used downstream of the contactor on the sweet gas to recover amine mechanical losses and prevent carryover of amine into downstream RFG.
Challenge
Environmental exceedances due to venting of offspec RFG from poor AGRU operation
Solution
Environmental compliance in the AGRU by control of foaming and fouling issues.
- Solid particle contaminants in amine systems are mostly very fine corrosion products that may not be adequately removed by filters that exhibit unloading, media migration, channeling or poor sealing.
- A range of absolute and nominal rated filter elements is available to reduce suspended solids to <5 ppmw, keep the amine clear, and reduce foaming and fouling issues.
- For enhanced solids control, add filtration to the rich side. Total sour gas worker exposure will typically be lowered due to the reduced system maintenance on the rich side.
Challenge
Caustic treater upsets from amine carryover in the sweetened LPG
Solution
Freedom from caustic treater upsets due to amine carryover from liquid amine treaters.
- Install a high efficiency liquid/liquid coalescer downstream of the liquid contactor to remove residual amine and ensure corrosion test quality is achieved.
Challenge
Rapid cleanup need
Key Application/Filter Recommendations (other applications not shown)
Application
1.
Contactor inlet coalescer
Customer Benefits
Refinery productivity, reliability and compliance via AGRU protection from slug upset
2.
Contactor outlet coalescer
Improve burner reliability and reduce burner maintenance by removing amine carryover
3.
Amine filter (Add rich side for enhanced performance)
Refinery productivity, reliability and compliance via AGRU protection from foaming and fouling causing RFG issues
4.
Liquid hydrocarbon removal from amine
Reduce upsets in downstream sulphur plant
5.
Amine removal from LPG
Improve caustic treater reliability, meet LPG quality specs (corrosion test)
6.
Depollution/cleanup filter
Rapid recovery from upsets, return to refinery productivity, reliability, compliance
Laurence Reid Presentations
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2018 - Amine Systems - Corrosion Overview, and Impact
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2017 - High Efficiency Contaminant Removal Improves New & Existing Sweetening Processes
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PDF version of this page
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Acid Gas Removal Unit (AGRU)
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Amine Sweetening
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