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Refinery Acid Gas Removal Unit (AGRU)

Ensure your AGRU reliably supports your daily production quotas and environmental protection needs.

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 liquidliquid 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





Reduced refinery shipments due to AGRU operational issues curtailing gasoline, jet fuel and diesel production 



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.

  • 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. 





Environmental exceedances due to venting of offspec RFG from poor AGRU operation 



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. 





Caustic treater upsets from amine carryover in the sweetened LPG 



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. 





Rapid cleanup need



Apply mobile filter or liquid/liquid coalescer skids.



acid gas refining process diagram


Key Application/Filter Recommendations (other applications not shown)




Contactor inlet coalescer

Customer Benefits


Refinery productivity, reliability and compliance via AGRU protection from slug upset


Contactor outlet coalescer

Improve burner reliability and reduce burner maintenance by removing amine carryover

Amine filter (Add rich side for enhanced performance)


Refinery productivity, reliability and compliance via AGRU protection from foaming and fouling causing RFG issues


Liquid hydrocarbon removal from amine


Reduce upsets in downstream sulphur plant


Amine removal from LPG


Improve caustic treater reliability, meet LPG quality specs (corrosion test)


Depollution/cleanup filter


Rapid recovery from upsets, return to refinery productivity, reliability, compliance

The Corrosion Fouling Cycle in Amine Systems

Read more

Amine Sweetening

An efficient filtration of the solvent loop is critical to capture the solid particles that contribute to foaming, fouling, and other operational challenges. Explore our solutions.
An efficient filtration of the solvent loop is critical to capture the solid particles that contribute to foaming, fouling, and other operational challenges. Explore our solutions.
Read more