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Is it feasible to reduce CDU heater HOT to reduce CDU column pressure ?
 
Answers
04/10/2016 A: Apoorv Gupta, IOCL Haldia, apoorv.work19@gmail.com
It is not recommended to reduce CDU HOT as no direct link is there with overhead pressure. Overhead will get pressurize only if more load is there on overhead condenser. Check your re-flux ratio. re-flux ratio should be in range of 0.8-1.3.
If column is operation with high re-flux then optimize circulating re-flux.
29/10/2015 A: Jayaraj Jayam, Chennai Petroleum Corporation Limited, njayaraj@gmail.com
Reduction of COT in CDU heater is not the right approach to reduce atmospheric distillation tower pressure. Column pressure can be reduced by maintaining proper circulating refluxes (pump arounds) flow and make appropriate condensation at each
level of products draw. Keep column top reflux at just required level. Excessive top reflux flow will contribute to increase the column pressure.It is just like adding something extra into a closed system and hence increase in total pressure.
Reduction of COT will lead to slippage of gas oil into reduced crude (long residue) and overload vacuum tower.