PID Temp Controller

[michaelb]

Does anyone have experience with PID controllers? I have a 40 gallon still with the reflux head from moonshinestill.com Currently I have an electric stove switch as the controll. The problem with that is it cycles on then off, not like a rheostat. It is difficult to control the head temp. The range when cycle on is from78-83C at the top of the column, which is ok except for that I watch and smell a lot of product loss. The cooling coil suggested on moonshinestill.com I feel is not enough. I started with a double coil without success, switched to a long single coil with similar result. Then took the double coil and put it in the freezer in an antifreeze solution to prechill the to the long coil in the head and still visually can see loss. I would recommend to other using that design to make the 3" round copper section 2-3 longer. During the run I can obtain 76% consistantly. I would like to upgrade to a PID controlled system. Im looking for specific controllers, thermocouplesor other advice.

[knuklehead]

I am using the same top end as you have. My lower element is controled by a Phason MSC-4 controling the voltage to my lower element.

This unit will only handle 1500 watts and with such a large boiler you are probably using more then that while running. I am not sure if Phason has a larger version but you could check it out.

[Arnie_sla]

If you can get one of these OMROM PLCs (see link below) they are great for controlling temperature at a constant temp. They can be set to sense every 2 seconds and the more time they operate the better they control. They actually "learn" as they monitor the temp, and adjust the time they turn the element on and off (duty cycle) so as to just keep enough energy being supplied to keep the temperature at the required temp.

You setup the sensor (a thermocouple or PRT) at the top of your tower and basically by the time the temp at the top of your tower even trys to drop or get too high the controller has adjusted the input to the element in your boiler and so the temp is being held constant at the top of your tower by applying little amounts of power in the boiler.

Of course you need to ensure that your element is not too powerful for your system. If it is too powerful, you will find that even these controllers will not be able to stop the temp from fluctuating as the element heats up too quickly, and applies a burst of power to the wash. You need to just be applying a little bit of heat to the wash to keep it at a constant boil, so a small element is better.

The only disadvantage is they are only able to out a max of 3 amps, But if you use the output from the PLC to control a 10 or 20 amp relay you will have no problems will high wattage element for large boilers

I have one of these OMROM controllers, I have a 15 litre boiler with a 80 cm tower and I have set up my elements in such a way as to give 2000 watts (fast boil) 1500 watts (medium heat up, not used much really) 875 Watts (slow heat, for reflux run). The controller is great at maintaining temp during run with minimum amount of power input to the element.

Operates using 100 volts or 240 volts 50/60 hz so is suitable world wide.

http://oeiwcsnts1.omron.com/pdfcatal.ns ... penElement" onclick="window.open(this.href);return false;" rel="nofollow