forced circulation reboiler percent % vaporization 2

[cheme89]

Hello,

I am installing an existing S&T exchanger as a forced circulation reboiler for a batch distillation. I know the max heat input from Q=UAdT and that translates into my vaporization rate. My question is, what % vaporization coming out of the reboiler should I design for which will define my circulation rate? I have some guides for thermosyphon reboilers which say anywhere from 15-35%, but no reference for forced circulation, other than to avoid mist flow in the exchanger.

I'd appreciate any suggestions from all you smart people out there, even if you just point me to a good reference.

Thanks.

 

[CJKruger]

cheme89, you can probably assume it is similar to a forced circulation fired heater which is typically design for 50 wt% vaporization.

 

[cheme89]

Thanks CJ. You wouldn't happen to know of an equation or method for calculating the film coefficient for boiling liquids inside vertical or horizontal tubes, would you? That one seems a little hard to come by.

 

[srfish]

For vertical tubes the Chen correlation is mostly used. It is found in I&E.C Process Design and Develoment 5(3):322-329, July 1966. There are numerous correlations for horizontal flow such as Gungor and Winterton, Shah and Kandlikar.

 

[ione]

For some of the correlations quoted by srfish (who deserves a star)

http://www.wlv.com/products/databook/db3/data/db3ch10.pdf

 

[cheme89]

Many thanks!