how could you digitally control still output temp

[mendodistilling]

I would like to build a rheostat that uses a temp probe to turn down as temps approach too high temperatures so there isnt any loss to evaporation once flow starts to trickle. i have a 26 gallon still with 30a 240v water heater element in it. id like to bring it up to 140 degrees then have it throttle speed to appropriate temps to help me avoid any losses on low wine first runs.

[Sherman]

Are you trying to control the liquid in the pot or the liquid exiting the condenser?

[mendodistilling]

im trying to control the heating element to control the element amperage to lower the amperage to slow the exiting condenser speed so the condensed liquid temp will be lower, below 64. I had a problem with a flash off because i forgot to run the water in time because i had the rheostat too high. i'd like it to sense temperature and adjust input amperage to slow output flow enough with the water running the whole time. i also was thinking of adding another solenoid to the water to start at 140 degrees because this is when i'm seeing flow and would like to leave the first distillation alone and run it slow so i can do stuff around the work area without forgetting to turn the water on at the appropriate time. i always tie a can on the neck but if im out of earshot its a problem. it seems easy enough i just needed some brainstorm juices.

[mendodistilling]

the pot temperature is 140 degrees, so its not relavant to the vapor in the swan neck, just a rough number that seems a consistent indicator and when my can falls off the neck. its a hill billy still and it has a triclamp on the top of the pot with a triclamp temp guage.

[Mars]

It probably isn't worth the time/expense to do this for a 26 gallon still, but how do you control power now? And do you mean 240F? There shouldn't be any vapor or any vapor left at 140 F or C.

[mendodistilling]

http://www.hillbillystills.com/Heat_Controller_p/hetgk.htm

the vapors are just starting to condense and are just starting to come over at 140, vapor is just getting warm enough to push through the condenser. i control power with an analog knob rheostat. it has settings 1-10 and amperages of 0-25amps.

[mendodistilling]

could you take a thermocoupler and a thermocouple pid and relay, wire it to the pot thermometers previous place, let it be set at x, and make it turn on the water solenoid? this seems simple enough. could you then wire another relay that runs your controller through another resistor to dial down amperage? I'm looking at prices for doing this and finding 9.00 thermocouple, pids and relays for pretty inexpensive, probably with the box for under 150-200.00 .

[bluestar]

Sure you can automate some of these things, but keep in mind when you do so, they should be designed to failsafe into a condition under which no damage or safety issues will occur.

We are planning to do something similar with our 60 gallon still, adding temperature probes in pot, in boiler, in lyne arm, in condenser water out, etc. The idea would be first just to monitor everything during regular runs and record it. Very instructive to understand how your process works. Later, add automation.

[nick jones]

I'm looking at prices for doing this and finding 9.00 thermocouple, pids and relays for pretty inexpensive, probably with the box for under 150-200.00 .

This valve will do everything that you need mechanically (i.e. without electricity) for about the same price:

http://www.danfoss.com/Products/Categories/List/RA/Water-Valves/AVTA-temperature-controlled-water-valve/AVTA-pipe-thread-connections-for-neutral-media/515fbfdf-f531-46da-9c7a-f7663e78213c.html

+1 on Blue's warning as well. I'm of the opinion that for most setups it is reckless to walk away from a pot still during heat-up.

Nick

[Swede]

If you choose to do electronic monitoring to turn on water at a preset temp, I suggest using a NO (normally open) valve that is held closed during heatup by your control circuit. Once the column/helmet/lyne arm is up to temp, the control setup would trigger the valve to open, having held it closed up until this point. Should there be a power failure to your controller you would default to water flow through your system. This would be offer a degree of intrinsic safety that some auto-water-on systems might not offer.

Personally I'd just leave the water on through the PC all the time if I was running a reservoir cooling system, with tap/city water for cooling there would be obvious benefits to turning water on once up to temp. Here the afore mentioned system would hold some merit.

[mendodistilling]

Sounds like a good plan, so in fact I was trying to leave the valve open and let water flow to the valve all the time and I do like the valve relay being failsafed to flow. That makes a lot of sense. Thank you!

[sailorman9]

I've been working on this same problem for years. Except my goal is to run the whole system via a smart phone. I use a pulse width modulator instead of a rheostat, much less wasted energy. The "valve salesmen" always think they have the system, but I believe a system like this doesn't exist. I envision a group of solenoid valves each attached to a preset needle valve. All solenoids open = full water; one solenoid = just a trickle. Email me and we can chat. Bluestar is right, you have to know your system.

[nick jones]

The "valve salesmen" always think they have the system, but I believe a system like this doesn't exist.

Sailor, you can "believe" what you want, but I can actually SHOW you a simple mechanical valve that modulates coolant water flow working on a REAL still (many, many stills actually - built by companies that have been around for over a century).

Let me know when you can show me that your "belief" that a series of solenoid valves are able to control the coolant water flow to a condenser has become a reality.

Nick

[Two Bit]

Ours has an automatic valve with a manual override. It's hooked into a thermostat and an alarm sounds if the vapors or condensate are at too high of a temperature. It's all part of the safety measures built in, which in my opinion should be mandatory for insuring a new distillery. Even with these measures we never have anybody leave the still. Someone is within smelling, listening, and watching distance at all times it is running. Running it via smartphone sounds tempting, but phones can't smell alcohol vapor before an alarm goes off. Or physically turn a valve if the automatic system fails. Or see if the column is about to flood.

Be safe. Never leave the still. Have automatic and manual controls.

[mendodistilling]

I wasn't going to go into this bc it is not appropriate but the still is within ear shot/ssmell/hearing of the can drop from my kitchen/living room, that wasn't the problem, my ignorant ass not turning the water on bc of distractions was the problem, haha. I'm trying to me proof it.