Solvent absorption
Solvent absorption is the traditional method for removing CO2 from syngas. It involves the feed gas passing through liquid chemicals that absorb CO2 and then release it at elevated temperature in another vessel. The same chemical can be used over and over again to perform the separation of CO2.
In pre-combustion capture, after the gasification of the coal, feed gas enters the absorption column. There, the gas comes into contact with the solvent and the CO2 is absorbed into the solvent. The other gases leave the absorption column, and the “rich” solvent containing the CO2 is then pumped to another column called a stripping column. The “rich” solvent is then heated to about 120°C, causing the CO2 to be released from the solvent. The CO2 emerges at the top of the stripper column where it is cooled to remove water and then captured. The water is returned to the stripper column and the “lean” solvent is pumped back to the absorber. On the way, the hot, lean solvent passes through a heat exchanger with the rich solvent leaving the absorber column. This cools the lean solvent and heats the rich solvent on its way to the stripper column.
The trials aim to
- Trial a potassium carbonate- promoted solvent system and compare its performance to the traditional amine solvent (MEA).
- Reduce the energy required to heat the solvent to release the CO2 and to cool the lean solvent and the CO2.
- Control or avoid the solvent degrading or corroding equipment.
- Improve the amount of CO2 captured/released by the solvent through the use of novel packing material in the columns.
- Understand the interaction between the solvent system and impurities present in the syngas, including H2S, CH4 and CO.
- Reduce the cost of carbon capture and make solvent absorption technologies more commercially viable.
