Synthesis processing, methane scrubbing

For raw synthesis gas from steam reformers with a higher H2/CO-ratio and a higher residual methane content, the methane scrubbing for the extraction of pure CO and crude hydrogen is more suitable than the condensation process. The process flow diagram is shown in Fig. 5.11. In the first, so-called scrubbing... 

The light gases such as methane and ethane are used as fuels in the refineries and may be burnt as waste products if not saleable. Propane and butane are denser. They are first scrubbed and then liquefied under pressure and stored in tanks. Butylene is produced in various refining processes. It is the raw material used in the synthesis of rubber. 

In some instances, it is preferable to use copper scrubbing to remove the last traces of carbon monoxide in the ammonia synthesis gas. This process usually is carried out at pressures in the range of 1000 to 1500 psi, which are intermediate pressures of the high pressure ammonia synthesis feed compressors. The copper liquor is circulated countercurrent to the synthesis gas, picking up the carbon monoxide as a copper ammonium carbonate-carbon monoxide complex and producing a relatively carbon monoxide-free gas. Methane and argon, however, are not removed they pass on with the hydrogen to the ammonia synthesis units. 

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