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# Hand Calculation For Condenser Duty For A Distillation Column

4 replies to this topic
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### #1 timshelka

timshelka

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Posted 13 July 2020 - 05:43 AM

I am in need of help. I need to do a hand calculation for a distillation column. i have done the material balance including the reflux rate and vapor rate and all the other stuff such as number of stages etc.

My overhead stream is at a dew point temperature of 60.4°C at a pressure of 11atm.

The overhead steam contains mostly DME which is 0.995wt%(dimethyl ether). I now want to calculate the enthalpy of the overhead stream before it enter the condenser. I know BP of DME is -24°C at atmospheric pressure. My initial assumption is that the enthalpy for that stream is evaluated using dme only as it contributes more than any of the other components.

I have tried using different methods but i am failing to calculate the enthalpy because i dont know how to calculated the enthaply of the dme at 11atm. Please help

### #2 breizh

breizh

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Posted 13 July 2020 - 06:10 AM

Hi ,

If your condenser is a total condenser you need only the Delta H of condensation (vaporization) .

Consider the documents attached :

https://www.ncbi.nlm...les/PMC4294737/

Good luck

Breizh

Edited by breizh, 13 July 2020 - 06:11 AM.

### #3 timshelka

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Posted 13 July 2020 - 06:30 AM

Looking at the article you provided, it gives the Hv as a function of a temperature. In my reporting will it be fair to assume that the calculated Hv at a temperature of 60.4degrees is the same for a wide range of pressure?

### #4 breizh

breizh

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Posted 13 July 2020 - 07:03 AM

Hi,

To add to my first answer take a look at Clausius Clapeyron equation using your favorite search engine or textbook .

Same for Trouton's law .

Good luck

Breizh

Edited by breizh, 13 July 2020 - 08:05 AM.

### #5 timshelka

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Posted 14 July 2020 - 12:38 AM

Thank you very much for your help