How to determine coking in the reboiler at the bottom of a distillation column
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How do the temperature and pressure of the tower change during the coking process in the reboiler?
If the heating medium is steam, then an adequate amount of steam cannot be supplied, and the temperature will decrease from the bottom of the tower to the top as a whole. Regarding pressure, I’m not sure whether yours is a vacuum tower, a atmospheric pressure tower, or a positive pressure tower; it’s too general to say anything definite. However, what you need to know is that it’s sufficient for the efficiency of the reboiler to decrease; the rest can be deduced from that.
The temperature at the bottom of the tower cannot rise; the steam used for heating does not liquefy after heat exchange.
Based on on-site experience, coking in the reboiler at the bottom of the distillation tower leads to 1. a decrease in the heat exchange efficiency of the reboiler, with the temperature of the fluid dropping after heat exchange (as can be seen from the temperature curve)； 2. The heat transfer rate on the other side of the reboiler decreases, and the temperature after heat exchange rises as coking becomes more severe ； 3. Looking more deeply, the temperature of the vapor phase at the top of the distillation column will decrease, which in turn affects the quality of the product range produced by the distillation column. 4. If there are pressure gauges before and after the reboiler, the pressure difference before and after coking will tend to increase gradually.
Is there a formula to determine coking?