Hydrocarbon Present in Amine Solvent Downstream of Absorber

Problem Definition

A South American Refinery Client requested assistance tackling the problem of hydrocarbon being present in their amine solvent (rich amine). The client reported an incidence of hydrocarbon in their acid gas stream going to SRU. They are looking into putting a flash tank in service for the amine circuit and require SRE’s analysis to determine prime location, operation guidelines, and instrumentation required. There was an existing flash tank and was put out of service long ago, the tank was designed as a charge drum for amine system. P&ID of the amine circuit was provided (flash tank situated after the lean-rich amine heat exchanger) along with their current option.

SRE’s Response

Within a couple of days of receiving the request, SRE reviewed the P&ID and information provided by the client to present the recommendations. Flash drum should be installed after the absorber, and before the lean-rich amine heat-exchanger, to ensure Hydrocarbon is condensed and a significant amount of H₂S is NOT flashed. As per industry practice, absorbers operating below 10 bar usually do not require a flash drum. It was advised to the client to further investigate the event of hydrocarbon carryover to ensure there is no permanent damage to the amine circuit/equipment.

A write-up was sent to the client explaining where the flash drum should be installed and what the limitations will be. In addition, operation guidelines and instrumentation requirements were also presented to the client. For the short term, the client was advised to ensure that the amine inlet separator is functioning well, and that extra precautions are taken to stop hydrocarbon from entering the amine circuit.


The client was fully onboarded with SRE’s recommendations. They will strive to ensure that the flash drum will be installed upstream of lean-rich amine heat-exchanger and that proper instrumentation will be used. Operation guidelines have been provided to the client and will be further refined as the need arises.

SRE continues to provide support to this client as they are in the process of the modifications.