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Continuous Column Distillation


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On 11/17/2018 at 11:50 AM, Jedd Haas said:

Pete, can you post a picture of your continuous still?

I haven't forgotten you Jedd. Can't work out how to get photos off my phone to this forum. Have a guy who can probably show me tomorrow.

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  • 2 months later...

Thanks ! That forsyth is a magnificent still and I had a good time installing, piping it and getting it up and running.

@Dehner Distillery Ive seen a few pictures of your continuous stills but have not gotten to see one in person yet. Do you have anybody running them in Cali, or Colorado?

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  • 2 months later...

This is great thread. 

I've just started building out a continuous column. The stripping section is 300mm/4800mm copper tube holding 14 perforated trays. That then feeds into the factionating section which is two X 200mm/6000mm copper columns with structured packing.  There is reboilers at the bottom of stripping section and the first of the 200mm columns. 

I hope to have a feed a rate of around 1000 litres per hour. I'm still unsure of the sizing of the condensers I'll need at the various stages, there is about five in the process to make this thing work. My target is to get better than 96% abv.   

For the guys getting their head around how it all works here is the best video I've found so far. 

 

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On 4/9/2019 at 3:32 AM, Modernity said:

This is great thread. 

I've just started building out a continuous column. The stripping section is 300mm/4800mm copper tube holding 14 perforated trays. That then feeds into the factionating section which is two X 200mm/6000mm copper columns with structured packing.  There is reboilers at the bottom of stripping section and the first of the 200mm columns. 

I hope to have a feed a rate of around 1000 litres per hour. I'm still unsure of the sizing of the condensers I'll need at the various stages, there is about five in the process to make this thing work. My target is to get better than 96% abv.   

 

FWIW Vendome makes a still a little larger than yours (12" diam) for 3.1gpm (700lph).  I don't think you'll get 1000lpm or normal wash feed through an 8" (200mm) rectifier at any reasonable vapor velocity.   

Reboiler design is a complex issue, particularly if you are processing wash grist-in.   Many stills this size and smaller use direct steam injection to avoid fouling.

Condensers are just heat exchangers, and they have to be sized to the load.  To get 100% reflux from a top plate you need to match the heat of vaporization of the two components (ethanol&water) according to there molar flow rates.

95.63%ABV is the azeotropic limit to water:etoh separation near atmospheric pressure - you can't get to literal 96%ABV that way.

 

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On 6/6/2019 at 6:46 PM, stevea said:

95.63%ABV is the azeotropic limit to water:etoh separation near atmospheric pressure - you can't get to literal 96%ABV that way.

 

Are you absolutely sure? I think you mean that 96.63% is the azeotropic limit. 

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15 hours ago, stevea said:

Yeah - mibad - 95.63% by mass, the ABV azeotrope is close to 97% ABV

Thank you for clarifying the confusion. I was starting to think I was living in an alternative reality.   

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On 11/9/2019 at 8:56 PM, Dehner Distillery said:

I build continuous stills.

www.redbootstills.com

It is very good that there are people who make continuous columns in the USA!
My respect!

But ... I looked at your continuous apparatus - why do you need 35 plates if you do not select different fractions in your column? it is very inefficient. You have a very tall column.
For stripping columns 6-16 trays are sufficient, depending on the quality of the inlet mixture.
I am designing stripping and fine columns.
 
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On 11/15/2018 at 10:32 PM, PeteB said:

The problem I have experienced with centrifugal pumps is if there is still some CO2 in the beer they cavitate especially if trying to push to a reasonable height ie. with back pressure. The flow control valve and column height would cause back pressure. Also any solids in the feed could obstruct the control valve. The centrifugal would be fine if no residual CO2 or solids.

I think the rubber type impeller pump which is a positive displacement type would be far less likely to have problems, Jo Dehner suggested the same.

1) the presence of CO2 in the inlet mixture is not a problem, it is good for distillation (stripping of the column). This increases productivity. You need to use an agitator in the tank that mixes the mixture before it enters the pump. It is generally useful to quickly stir the mixture in the tank in front of the pump, and add an antifoam agent to the tank, at the rate of 50 ml per 100 liters. An antifoam agent based on silicon, it is inert and does not affect taste and smell, but it will remove foam. Foam is the biggest problem with fast distillation.

2) if there is a lot of CO2, you can install a simple device that will remove excess CO2 in front of the column enters. This device is more than 50 years old :) I can give a picture and a description of its operation. But I repeat: CO2 in the inlet mixture is useful and increases the productivity of the column.

3) accurate feeding of the inlet mixture is very important for the stable operation of the column. The use of impellers (pumps for pumping the mixture) has the main problem: these pumps allow the mixture to "slip" past the pump impeller, that is, the pump cannot keep the same pressure in the system under different loads. There must be no valves in the circuit from the pump to the entry into the column! You can consider displacement pumps, but they can become clogged with mixture.
An excellent solution for very accurate feeding of the inlet mixture with grains and impurities is the peristatic pump. There are a lot of peristatic pumps of different capacities, pump controllers allow very precise dosing of the mixture supply. The peristaltic pump is not afraid of impurities (grains) in the mixture flow.
 
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