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Trouble Shooting Batch Distillation Column

distillation column

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#1 rikakose

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Posted 03 June 2019 - 09:34 AM

Re phrase the question


Edited by rikakose, 04 June 2019 - 10:21 AM.


#2 PhilippM

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Posted 03 June 2019 - 04:48 PM

I am not that experienced with batch distillations, but simply by reading the post, one should usually at least be able to understand the question.

However, I don't really understand what problem the client is having and what he expects "the most simple solution" to accomplish. Is the low pressure (underpressure protection) the problem? If that is the case, I wouldn't rely on the gas from the scrubber/other equipment to avoid underpressure in the column/drum (in fact the gas might cause further problems like air ingress/explosive atmosphere) and instead install a vacuum relief valve that allows the Inbreathing of nitrogen to the condenser.



#3 breizh

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Posted 04 June 2019 - 12:49 AM

Hi ,

I've difficulties to understand how you can get so low pressure during this process . Can you elaborate or share a Pressure profile versus time together with a temperature profile ?

I've been operating system similar to the one you drew . Can you confirm you don't have any device to pull the vacuum , let say ejector or vacuum pump.

 

Breizh



#4 breizh

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Posted 04 June 2019 - 05:35 AM

Thanks ,

What is the fourth curve ?

What is the objective of the distillation ? separation between which products ( boiling point light components  and heavies) ?

how the still is managed ?  visual ? how the heat is applied ?

Breizh



#5 rikakose

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Posted 04 June 2019 - 05:56 AM

Thanks ,

What is the fourth curve ?

What is the objective of the distillation ? separation between which products ( boiling point light components  and heavies) ?

how the still is managed ?  visual ? how the heat is applied ?

Breizh

 

Pressure drops to below 700 mbara, the operator closes the vent line. Then pressure is built up again. Then they open the ventline again. 

 

 

The fourth is the opening of the steam valve to the steam coil in the column. 

objective is to withdraw some light product b.p 86ºC. Steam valve is further opened when starts withdraw meanwhile reflux is stopped.  

There are some problem with the packing of the column, column doesn't functioning very well. 

The amount of light product is the target. 



#6 breizh

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Posted 04 June 2019 - 06:33 AM

Hi ,

Any chance to have the coil damaged and you carry over  steam to the overhead condenser  …..steam collapsing creating vacuum ?

If you have steam leaking  you may have a great chance to damage your packing .

You should consider to investigate the hardware .

Was it the case at the start up of the unit ? let you find the base line of the process.

 my 2 cents

Breizh



#7 rikakose

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Posted 04 June 2019 - 06:58 AM

Thanks for the reply. 

 

The light product is on spec. So, chance of steam leaking is low. 

The product is deeply subcooled. I think that is the reason of the vacuum. 

 

My question is :  the top of column and drum pressure equal? Is there any chance that they are not equal? Drum pressure is higher than column?  From condenser and drum, the gravity flow line has around 2 m horizontal piece. Do I need to add equalizing line between column and drum?






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