2 replies to this topic

[maazulmosaid]

Hi !

 

 

I want to expand a mixture of ethanol ,ethene and water vapors at 68 bar. I want to expand this mixture and then seprate in flash tank.

 

please guide me how can i do this. How should I size the flash tank. Give me refrences or equations if possible.

 

Thanks in advance

[ski]

68 bar seems a very high pressure - are you sure this is correct?

 

You could probably separate the ethene (tops) from ethanol and water vapors (bottoms) using flash distillation. You could then use a distillation column to separate the ethanol and water, with ethanol rich stream leaving from the top and water rich stream from the bottom.

 

The vapor and liquid compositions as well as the flowrates must be known to size a flash drum.  First determine K_drum which is an empirical constant which depends on the type of drum - find a correlation equation in any separation process book (usu. between 0.1 and 0.35 for vertical drums). Then use this to determine the permissible vapor velocity at the maximum cross sectional area -  formula in any separation book.  Using the known vapor flowrate and the calculated vapor velocity, solve for cross-sectional area, and then diameter. The length can then be calculated using a rule of thumb that the length over the diameter is between about 3-5.

[maazulmosaid]

Thanks for reply. Good to see people are helping each other without any greed

 

Yes the pressure is 68 bar in reactor.

 

I know how to size the seprator. My main concern is the expansion of gas or mixture.

Do you think specifc volume of gas has anything to do with this?