Low-temperature methanol washing
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For the synthesis of methanol using low-temperature methanol washing, refrigerators can reach temperatures as low as -20°C; so how is it possible to cool methanol to -60°C? Why can heat exchange also occur when it is running while driving?
Your question is not clear. The chiller converts gaseous propylene into a liquid state by applying pressure and cooling it; the liquid propylene is then vaporized under reduced pressure, which helps to provide cooling for the entire system. Methanol absorbs acidic gases, causing its temperature to rise, and when these gases are released, the temperature of methanol drops. Therefore, the lowest temperature in the methanol washing process occurs in the regeneration tower
The main sources of cooling capacity in low-temperature systems are ice makers, methanol for carbon dioxide separation, and water coolers. The temperature can drop to minus sixty after methanol is used to separate carbon dioxide. The temperature at the location where the chiller provides cooling cannot drop that low; generally, the temperature produced by a chiller is in the range of minus twenty to minus thirty degrees. The minus twenty you mentioned probably refers to the maximum cooling temperature of the methanol cycle chiller, which can reach minus twenty degrees. If you want to lower the temperature further, you need to introduce air
Excluding heat loss, the temperature can only be reduced to -47.7°C through the cooling effect generated by the flashing of propylene; it is only after CO2 is absorbed that the methanol-rich stream, after undergoing heat exchange in the propylene cryocooler, undergoes desorption, allowing the temperature to drop further. Therefore, as the saturation of CO2 in the methanol increases after gas introduction, more CO2 is desorbed per unit volume of methanol, and the temperature continues to decline.