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Liquid Collector In Batch Separator Tank

separator; collector

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#1 Marshall Paliga

Marshall Paliga

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Posted 01 December 2020 - 07:49 AM

Hello fellow engineers!


This is my first post is this forum, so I'll introduce myself.

I am Marshall, 25 years old Brazilian engineer working primarily with biodiesel.


My situation:

The company for which I work uses a multi-purpose cylindrical vessel, flat bottom, for vegetable/animal oil hydrolisis/esterification followed by phase separation (ester/glicerol static separation). Schematic drawing attached.


It is a 140 cubic meter vessel (diameter = 4.5 meters; height = 9 meters). Agitation is provided by pump recirculation. Reaction works pretty well. Separation is acceptable. After separation, the phases are pumped out of the vessel from 4" side nozzles, one at a time.



The main problem happens in the emptying step. We cannot allow glycerol (heavy) in the ester (light) phase, thus, we usually lose ester in the glycerol phase. This usually isn't a huge problem in continuous separations, but seems unavoidable in batchs.


My objective is to mitigate the ester loss. We have considered:

  1. Reducing flow rate in the emptying step;
  2. Using some sort of liquid collector (internal collector; various smaller nozzles at the same height around the vessel).

Seeking for any advice/bibliography on the subject.


Best Regards.



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#2 breizh


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Posted 01 December 2020 - 08:14 AM


Any chance to detect a change in physical properties, let say difference of conductivity of the phases ?

If yes you can install an in line electrode to monitor the operation and stop the pump or other on/off valves .

I used this type of set up to recover an organic phase with minimum aqueous phase .

Hope this is helping you.


#3 Marshall Paliga

Marshall Paliga

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Posted 01 December 2020 - 11:28 AM

Hi Breizh,


Thank you for the reply.


It is possible to detect differences between phases. In continuous processes, the separators usually have coupled density meters for this operation.

In an old project we've tried to do in line density based automation. It was not efficient. The problem was phase mixing while pumping. Probably poor design.

I think a similar problem will happen in this case. The shape of the reactor isn't exactly adequate for this purpose. When trying to pump out the ester phase, the glycerol that's right below the nozzle tends to be sucked. That's why I thought of a liquid collector of some kind. Something that distributes the flow, reducing the velocity in the suction point.


Can you please give more details about the setup that you've used? 



#4 breizh


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Posted 01 December 2020 - 06:25 PM


My experience :

2 plants , one in Asia , one in Europe producing esters in batch reactors . 

After reaction the product is washed with an alkaline solution several times  After a while the phases are separated to recover the organic part .

One plant drains the aqueous phase from the bottom of the reator , watching closely the appearance of organic using a sight glass , this keeps an operator busy with sometime losses 

The second plant withdraws the material from the top of the reactor using a dip pipe coupled to a pump , on the line there is a sensor ( probe) which detects the aqueous phase and minimize the contamination by stoping pump detecting the change of conductivity of materials. 

Same process but different way to operate . 


Hope this is helping you .


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