To remove the acid gases such as H2S, COS and CO2 from the BTL
process, a pilot-scale methanol absorption tower producing 1 BPD
of diesel was developed and the removal characteristics of the acid
gases were determined. Prior to long-term operations, the influences
of experimental variables such as methanol flow rate,
temperature and pressure on the methanol absorption tower were
measured and modeled using Aspen Plus. An increased methanol
flow rate and pressure increased the removal rate of the acid gases.
Conversely, the acid gas removal rate decreases with increasing
methanol absorption tower temperature. The optimum operation
conditions were then determined for long-term operations. A total
operation time of 500 h was achieved with several BTL experiments.
Although the aqueous scrubber was installed for the BTL
process, it was not sufficient for treating H2S and COS
biogas in an engine.