|
 |
|
This process serves for upgrading the biogas to natural gas quality. The pressure water scrubbing was until now mainly used in Europe. The process is based on the physical effect of dissolving gases in liquids. |
|
 |
|
The dissolubility increases with higher pressure; this is why the process works with compressed biogas. To separate the biogas from the CO2 and H2S components it is compressed to 20 bars and then introduced to the bottom of an absorption column. Water is sprayed from the top of the column water is sprayed so that it flows down counter currently to the gas. The absorption column is fitted with packing material to ensure a high surface for gas liquid contact.
The methane content in the biogas approximates 98% after a drying stage and is ready for being introduced to the common natural gas pipe work.
A partial stream of the water is extended via an extension tank and is freed from the gases contents by a stripper. Afterwards it is compressed and routed back to the column. Ammonia and H2S can be absorbed in diluted sulphuric acid and is then retrieved as ammonia sulphate fertilizer. The CO2 is released to the atmosphere. |
|
|
|
|
|
|
|
|
|
|
