Pressure control of the distillation tower
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What is the effectiveness of using variable-frequency control with high-efficiency air-cooled motors for the top pressure control of C3C4 distillation columns? Will the adjustment be delayed? Those who have used it, share your experiences.
We haven’t used it; we adjust the circulating water valve of the on-site circulating water cooler manually, and the pressure remains relatively stable. With air cooling, the reaction should be faster than with water cooling.
I would like to ask: when using air cooling with variable frequency control to regulate the temperature after cooling, is it better to place the temperature sensor at the air cooling outlet or at the water cooling outlet downstream of the air cooler? What are the advantages and disadvantages of each?
If variable frequency control is used to regulate the temperature after cooling by air cooling, it may be difficult to obtain accurate readings at the air cooling outlet; especially when the load on the air cooler is low, there might be a liquid phase present in some of the tubes. Especially in locations such as the top cooler of an deethanizer, the cooling temperature and pressure are primarily controlled by changing the height of the liquid column. When cooled by water, the advantage is accurate temperature measurement, but the reaction is slower and there is a delay in adjustment.