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[halkeshhulk]

Dear All,

 

We often see Fractionation columns with only top reflux and few fractionation columns with Pump back reflux and top reflux configuration.

 

Q1. What is the basis to introduce Pumpback reflux in a fractionation column along with top reflux flow configuration?

 

Q2. Like Optimum Reflux flow maintaining at 1.2 to 1.5 times to minimum reflux flow, is there such any rule for pumback reflux flow? ( Optimum Pumpback reflux flow)

 

Q3. How the variation of pumpback reflux flow affects the distillation of intermediate product cut and its immediate bottom cut? 

 

Kindly guide me. Thanks.

[breizh]

Hi,

Consider this link, you may find pointers.

Separation Processes, Second Edition

pump back = internal reflux.

This is managed by temperature control and side draw flow rate (mass balance) thus Q2 is meaningless.

For Q3, if you change the internal reflux you are going to change the operating lines with the consequences on top cut and bottom cut of the column.

Breizh