Why is it more reasonable to use low-temperature methanol washing combined with liquid nitrogen washing in the purification process?

This post was last edited by 654262293 on 2010-9-9 at 10:44. Since the operating temperature for liquid nitrogen washing is -190 degrees, at this temperature liquid nitrogen can absorb carbon monoxide, methane, and argon. However, at this temperature carbon dioxide, water, and methanol will freeze; therefore, it is necessary to remove trace amounts of carbon dioxide, water, and methanol before proceeding with cryogenic treatment. The temperature achieved in low-temperature methanol washing is -57 degrees, which allows for pre-cooling prior to liquid nitrogen washing while also helping to remove trace amounts of carbon dioxide and water. Of course, molecular sieves are used before entering the cryogenic stage to ensure that all trace amounts of carbon dioxide, water, and methanol are removed. At the same time, the low-pressure nitrogen used for regenerating the molecular sieve with liquid nitrogen is also employed as the stripping nitrogen in the hydrogen sulfide concentration tower of the low-temperature methanol washing process, thereby enabling the recovery of cooling capacity; using both together is the most reasonable approach.

This post was last edited by 654262293 on 2010-9-9 at 10:45. What was said above is very accurate; in essence, it can be summarized in two points: 1. The heat loss incurred in the liquid nitrogen washing section due to the low temperature of the outlet syngas can be addressed through optimization in conjunction with the low-temperature methanol washing section, so as to compensate for this loss. 2. The regenerated gas from the adsorber in the liquid nitrogen washing section can be used as a stripping agent in the low-temperature methanol washing section.