Dephlegmator Control via Vapor Temperature?
Posted: Thu Jan 07, 2016 5:57 pm
I'm noodling through a concept that I recently saw at a micro-distillery that I visited. Their hybrid column was set up so the coolant to the dephlegmator was controlled by the temperature of the vapor at the top of the column. They had a controller box that they could set the threshold temperature to turn on the coolant. I asked whether they were controlling the temperature of the coolant, and the distiller said no, they were monitoring the temperature of the vapor at the top of the still, not the coolant.
This was new to me, I had heard of controlling the coolant by the temperature of the coolant exiting the dephlegmator, reflux ratio or rate of production. But vapor temperature kind of makes sense--you set the controller for the vapor temperature of the abv you are targeting and the controller will cycle the coolant valve to maintain that temperature / abv. The system will crank away at that abv until it cannot hit that abv based on your theoretical plates and remaining abv in the boiler.
Seems like this could be useful in a couple of ways. My focus is making bourbon, but with a CM column I'm always looking for ways to keep the abv on the relatively low end (around 120-130 proof), usually by dialing back the reflux using a needle valve. A high vapor temperature setting would be good for hitting a lower abv. For NGS a temp close to the azeotrope would give a high proof product. In both cases the still would run at the abv associated with the temperature until the still could not produce that abv any more. Not sure whether this would work as a good tails cut, but it would definitely give you a sign that the run was reaching an end.
Curious if anyone has seen or used a still that controls the coolant this way. Any downside to running a still this way? I did a few searches here and did not come up with anything.
Best, JW
This was new to me, I had heard of controlling the coolant by the temperature of the coolant exiting the dephlegmator, reflux ratio or rate of production. But vapor temperature kind of makes sense--you set the controller for the vapor temperature of the abv you are targeting and the controller will cycle the coolant valve to maintain that temperature / abv. The system will crank away at that abv until it cannot hit that abv based on your theoretical plates and remaining abv in the boiler.
Seems like this could be useful in a couple of ways. My focus is making bourbon, but with a CM column I'm always looking for ways to keep the abv on the relatively low end (around 120-130 proof), usually by dialing back the reflux using a needle valve. A high vapor temperature setting would be good for hitting a lower abv. For NGS a temp close to the azeotrope would give a high proof product. In both cases the still would run at the abv associated with the temperature until the still could not produce that abv any more. Not sure whether this would work as a good tails cut, but it would definitely give you a sign that the run was reaching an end.
Curious if anyone has seen or used a still that controls the coolant this way. Any downside to running a still this way? I did a few searches here and did not come up with anything.
Best, JW