Stripping and flashing in low-temperature methanol washing
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How is cold generated in low-temperature methanol washing for carbon dioxide stripping and flashing? Don’t flashing and stripping remove relative heat? If that’s the case, then why does the carbon dioxide gas obtained through flashing and gas extraction become colder than the temperature of the methanol rich in carbon dioxide?
This is the cooling effect: carbon dioxide vaporizes through flashing, and this process absorbs heat, just as liquid nitrogen evaporates. Although it evaporates when heated, it continuously removes heat from its surroundings as it does so, resulting in a decreasing temperature
When circulating methanol absorbs carbon dioxide in one tower, heat of solution is generated; therefore, an inter-stage cooler is installed to reduce the temperature. At the second tower, carbon dioxide is desorbed, absorbing heat. You say that carbon dioxide releases heat when it dissolves, and no heat is absorbed when it is desorbed; moreover, the methanol in the cycle doesn’t dry out either.
:victory::victory::victory: Dissolution is exothermic, flash evaporation is endothermic, and then there’s the J-T effect; it seems that except for hydrogen, most gases absorb heat when under reduced pressure