Automating advice for a distillation machine for a research lab!


I am attempting to make a distillation machine autonomous and I need some help with the electrical and programming aspect. I need to take 120V AC from a wall outlet and send it to the 115V 50/60 Hz distillation machine and to a 12V DC window motor. These components then need to be sent to an appropriate controller, either a raspberry pi or PLC, in order to communicate with a thermocouple and a photo electric laser. I know I need some sort of relay, distribution board, or AC to DC converter. Would anyone happen to know a cheap and easy way to do this? These components would be programmed in an on/off type of way so I also could use some advice on which type of controller to use. This project is not too complicated, however I could use an experienced opinion.


Project to automate a distillation apparatus

You need to draw out a diagram and write out a control narrative - what is connected to what, for what purpose/reason, so that an object like a window motor has some significance in your control strategy. Labeled blocks, lines and arrows work for a diagram, words work for a narrative.

Without either, there remain some very basic questions:

Is the distiller a commercial product? Or are you converting a coffee maker? Does it distill by electric heating/boiling water? How is the water cooled for condensing? by ambient air or by some form of refrigeration?

Is the heating element in the distiller controlled to/at a certain temperature (thermocouple)?

What does a window motor (whatever that is) do in a distillation apparatus?

What does the photo-electric laser do in your control scheme?

How does water get into the distiller? What prevents the water from overflowing? How does the water know when to stop flowing? What starts and stops the water flow?

What happens to the condensed water exiting the distiller? Can it overflow the water container?

What happens if the water in the distiller runs out/runs dry? Will the heater continue to run and burn your house down?

Could the boiled water ever be contained to the point that steam pressure could build and the device explode? For instance, if the power goes out, the water cools and any steam condenses. But then the power returns, the heated water boils, pressure builds up and the condenser explodes?


In automation, ‘components’ are not sent anywhere. Sensor signals and control signals are communicated back and forth.

A power supply (what you call a converter) supplies DC power to specific elements/components. It does not control anything, it just supplies appropriate power to the components.

To size a power supply you need to know exactly how much power is consumed. How much current (amps) does the window motor draw?

To turn the AC on or off to the heating element, you need to know how much current the heater element draws.

Picking hardware is putting the horse before the cart. It isn’t clear what the control scheme is yet.

You don’t have an I/O count, nor a list of what the control signals need to be, not whether you need timing or counting operations, or more analog than a thermocouple for pressure control.

That said, “Programmed in an on-off way”; you might consider adding a 3rd choice to your control scheme - relay logic - in addition to the PLC or raspberry pi controller. Doing control with relays and timers can be an advantage because relays and timers (in many cases) are already capable of handing real-world ‘loads’, whereas micro-electronics are not so equipped.

Thank you for the descriptive response. It seems there is more to this than I thought. The instrumentation is a Koehler k45000 distillation apparatus. It works by switching on a breaker that is directly receiving power from a wall socket. It needs 115V AC to operate. It is heated to a certain amount but the boiling point for the fuel blends to be distilled lie somewhere in the middle. Instead of switching the breaker on and off and switching out the test tubes over and over (not to mention reducing human error) I decided to make it automated. The idea was to use a K type Omega thermocouple connected to a display (LED) that would display the current temperature of the heated fuel blend, have it attached to a button which could be used to ‘set’ the temperature to keep constant (essentially eye balling the boiling point). This would then be connected to the PLC so that it could communicate with the power source to either turn on/off repeatedly or somehow do a percentage of the power the distillation receives in order to reduce the amount of heat (I’m not sure exactly if this would work like I’m hoping). In addition, a 12V DC window motor having a stall current of 28A would also be attached to the PLC to rotate the cylinders collecting a percentage of the distillation. This would communicate with a small/cheap photoelectric laser (model unknown) that would read the height of the liquid and rotate the window motor once the desired height is achieved. So the programming logic would look something like [POWER > TURN ON, THERMOCOUPLE > DISPLAY TEMP > SET TEMP > IF TEMP IS SMALLER THAN A SMALL DEVIATION OF SET TEMP TURN POWER ON OR IF TEMP IS LARGER THAN A SMALL DEVIATION OF SET TEMP TURN POWER OFF, LASER > HOLD MOTOR STILL UNTIL LASER IS TRIPPED > ROTATE MOTOR (x amount of time) > REPEAT UNTIL BREAKER IS TRIPPED IN WHICH THE PROGRAM WOULD RESET.]

The logic doesn’t seem too complicated. I just don’t have a clue on how to electrically set it up. I’m looking for the cheapest, most efficient way. Somehow the wall socket needs to be the power source for all the components if that is possible and everything needs to be done with a PLC (or something easy and cheap).

The project is much more involved than you assume. There are safety issues.

This is distillation of fuels - and the fuel drips into an open container. Wow. In the industrial world, the presence of fuel or fuel vapors is a Class 1 Div 1 hazardous area which requires compliance with all sorts of electrical codes so that electrical devices do not become an ignition source for a fire or explosion.

I notice the Koehler offers an automated unit, the K45603 with “Integrated automatic fire extinguishing system”. Not surprising.

These are red flags to me. English appears to be your native language so you could reside in the very litigious USA. I can be tracked down, and I don’t need the liability of becoming a defendant in a law suit because I offered advice for a project that was an ignition source in a lab fire, so I’m backing out at this point.

Fair enough. Thanks anyway.