Acid gas removal

Acid gas removal

  • Acid gas removal

    Before entering distribution pipelines, natural gas needs to be purified from acid gasses CO2 and H2S to prevent pipeline corrosion. Next to being corrosive, H2S is also highly toxic, allowing only small traces to be present <4ppm). For CO2, the pipeline specification often is set at 2 or 3%, with an additional reduction required (<50ppm) if the gas is turned into liquefied natural gas (LNG).

    Most commonly used technology is amine treatment. Although it requires the use of nasty chemicals and the process requires a great deal of maintenance, it is a cost effective technology if gas volumes are large and the CO2 concentration in feed gas is relatively small. Because an amine solution needs to be re-generated with heat, treatment of high CO2 feed gas is energetically not so favourable. In that case using membrane technology gives several benefits. Next to the absence of nasty chemicals and low maintenance, there is an economical benefit because there is no re-generation required.

    Suitable membranes have a high permeation of CO2 and H2S in comparison with hydrocarbons. The acid gasses end up in the permeate stream, leaving sweet product gas.

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  • Fujifilm has commercial acid gas removal membranes, under the ApuraTM brand. Strong features of ApuraTM membranes are high performance and robustness against moisture and BTEX.

    Feed gas = Raw natural gas
    Retentate gas = Purified natural gas, mainly CH4
    Permeate gas = CO2 and H2S

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