Pressure-swing adsorption energy requirements

A number of system approaches can be used to clean up the fuel feed. These include pressure swing adsorption, membrane separation, methanation, and selective oxidation. Although selective oxidation does not remove CO2, it is usually the preferred method for CO removal because of the parasitic system loads and energy required by the other methods. In selective... 

The gas is then cooled to 30-50 °C and the carbon dioxide is removed by amine absorption or other processes. The remaining impurities - carbon monoxide, methane, nitrogen, argon - are removed in a final pressure-swing adsorption (PSA) step to yield >99.5% pure hydrogen. One of the main problems with this process is that the carbon dioxide is removed by the amine unit as a low-pressure gas. This gas must be compressed to 80 bar to be pipelined for sequestration. This compression step alone requires massive compressors and uses 4—5% of the total power output of the plant. The amine treatment step itself uses even more energy, so the total energy consumption is 15% of the power produced by the plant. 

The separation of a gas from the rest of the gaseous stream is traditionally carried out by means of pressure swing adsorption (PSA), cryogenic separation and absorption processes. However, the application of membrane systems is rapidly evolving on the commercial level owing to the advantages related to low capital costs, low energy requirements and modularity. 

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