What are the refrigerant and heat transfer fluid in low-temperature distillation? How is it controlled?
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I’m encountering some issues related to low-temperature distillation, such as the separation of substances like methane, ethane, ethylene, and propane. Even when the pressure is increased to over 10 kilograms, their boiling points remain in the negative dozens of degrees; in such cases, what heating method should be used for the bottom of the distillation column? What should be used for condensation at the top of the tower? There are also systems such as chlorinated hydrocarbons like difluoromethane, difluorobromomethane, and difluorodibromomethane; under pressure, the temperature at the top of the tower is -20 degrees, while that at the bottom of the tower is around 60 to 70 degrees. For such systems, it seems appropriate to use hot water for heating the bottom of the tower, but what coolant should be used at the top of the tower? Cold salt water?
The last edit to this post was made by EdwardLau on 2016-2-23 at 20:29. The low-temperature methanol washing of syngas involves cooling through the evaporation of liquid ammonia, and then the ammonia vapor is compressed to further reduce the temperature, which can be brought down to around -30 degrees Celsius
It’s similar to evaporative cooling; liquid ammonia is a common refrigerant.