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Automated Still Control


HedgeBird

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I am in the process of building my still and was just curious how many people have automated, or semi-automated control panels for their stills.

I have already started work on a panel for my mash tun that will use a PID unit to monitor temperature and control a steam valve, as well as have a switch for the pump and a timer, etc. Basically a simplified version of the Electric Brewery Control Panel: www.theelectricbrewery.com/control-panel

With the mash tun its pretty simple; monitor temperature, control steam.

The still on the other hand is not so straight forward. I am building a 150 gallon, steam powered, 4 plate pot still with a dephlegmator. The way I see it there are two data points I could potentially monitor, the collection vapor temperature or the dephlegmator cooling water output temperature rise. And also two inputs that could be controlled, the amount of steam (energy input) or the rate of dephlegmator cooling water flow.

So potentially I could use a PID to monitor cooling water temperature rise or vapor temp, and adjust steam input. I don't really think this would get me much though..

Another option would be to monitor cooling water temperature rise and adjust its speed to maintain consistent reflux. With this arrangement adjusting the setting on the PID would control the amount of reflux. Steam input would be manually controlled and vapor temp would just be monitored with an alarm set at various collection points. This arrangement seems like it would be more practical.

The easiest option would be to skip the 'control panel' and just build a 'monitoring panel' with displays for cooling water temp, vapor temp, and an alarm.

So yeah. I'm curious if anyone else is using a PID or other type of controller, what their setup and experience are. Or if you just have feedback on if you think this would be helpful or is just overkill..

-Hedge

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hi Hedge,

I am just now finishing my own control panel. I also based in on the Electric Brewery design, with a PID; I also simplified it quite a bit and made various other changes. After running it a while, I plan on expanding the design in some ways similar to what you mentioned.

Check out this thread: http://www.artisan-distiller.net/phpBB3/viewtopic.php?f=62&t=4792

That site is run by the same Sherman that VB mentioned; and on that thread you'll see some of the panels that the author (Swede) made for VB.

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Hedge,

I think that you will find that PID's are great for mashing control, but not as helpful as you'd assume for control of heat input for distillation. Any panels that incorporate PID or any other type of temperature controller are very useful as safety devices, max jacket temp monitoring, or overheat/end-of-run shutdown devices.

Controlling distillation heat input is best done by monitoring vapor temp above your top plate if you are determined to do it this way (IMHO).

HTH

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Another option would be to monitor cooling water temperature rise and adjust its speed to maintain consistent reflux.

On our still this is accomplished with a simple mechanical thermostatic valve manufactured by danfoss (part no 003n8230). It is similar to a refrigerant valve but made for cooling/heating water duty. I like that there are no electronic parts to worry about.

The valve itself is plumbed into the cooling water supply, and the thermoprobe of the valve is put in an appropriate place downstream (like the outlet of the condenser or the dephlegmator). This particular model can be set to maintain a process temperature at that point of 20-60 C.

Consequently, any change in heat input is automatically compensated by the valve, since the temperature of your cooling water will either rise or fall given more or less heat input.

Have fun,

Nick

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In my experience with still automation, PID's are just one aspect. I use them on our large gas fired stills, but they are networked to a larger PLC for full automation. The reason I do this is to give an element of fail-safe control, and manual control if the PLC has a brain fart. PID's are usually bullet proof, PLC and higher can falter. It also takes the load of temp control away from the PLC. Happy to chat on-side if you need some advice. Currently we have 4 fully automated stills, they are capable of running completely un-attended. Do not ask me for my algorithms for determining cuts :-)

Our setup is a series of network PLC's and PID's, using a PC/Database with a custom application controlling all via SCADA.

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I forgot to mention, when automating non electrical heating sources (steam, gas etc) you need to ensure a fail-safe design. Meaning, if the PID/PLC has a spasm, the burners/steam valves are shut off. I always have used a simple over temp thermostat (non resetting) in series with the supply voltage for the gas/steam valves, it has saved me many a time from crashed PLC's or badly configured PID's.

Also, test the hell out of the programming, limits and alarms.

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On our still this is accomplished with a simple mechanical thermostatic valve manufactured by danfoss (part no 003n8230). It is similar to a refrigerant valve but made for cooling/heating water duty. I like that there are no electronic parts to worry about.

The valve itself is plumbed into the cooling water supply, and the thermoprobe of the valve is put in an appropriate place downstream (like the outlet of the condenser or the dephlegmator). This particular model can be set to maintain a process temperature at that point of 20-60 C.

Consequently, any change in heat input is automatically compensated by the valve, since the temperature of your cooling water will either rise or fall given more or less heat input.

Have fun,

Nick

Nick, this sounds like a great option! Very simple and practical and for sure worth considering.

Thanks for the heads up, and for providing the specific part number!

-Hedge

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In my experience with still automation, PID's are just one aspect. I use them on our large gas fired stills, but they are networked to a larger PLC for full automation. The reason I do this is to give an element of fail-safe control, and manual control if the PLC has a brain fart. PID's are usually bullet proof, PLC and higher can falter. It also takes the load of temp control away from the PLC. Happy to chat on-side if you need some advice. Currently we have 4 fully automated stills, they are capable of running completely un-attended. Do not ask me for my algorithms for determining cuts :-)

Our setup is a series of network PLC's and PID's, using a PC/Database with a custom application controlling all via SCADA.

Rich, color me impressed. Did you do most of the work creating your system on your own? With a setup like this I assume you are controlling both heat input and cooling input? To reduce steam input do you have some type of variable valve or do you just let the PIDs intermittently cycle the valve open/shut?

I think anything resembling true un-attended automation will have to wait for my next still build! :)

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  • 3 months later...

A BCS-460 from embededcontrolconcepts.com would be a great starting point...(you still build the panel with contactors, SSR's, relays, etc) It incorporates PID in software, and also has dataloging and ethernet access (you can monitor from your phone/tablet/etc), you can watch the vapor and liquid temps, vary the duty cycle of an electric heater for a quick warm up then whatever %power your condenser can handle, shut off when a temp reaches a certain point, etc.. The forum has lots of helpful folks with experience in many different areas...

Obviously you would want to do the fail-safe and general good design practices, but the controller is a steal at less than $200, considering the intellectual property in it, and the cost of other PLC systems with PID control... Here is my brewery with the BCs-462 (next model up, but I would get just one of the 460's for each still) ...

When I get my DSP, this is what I will be using.

-mike

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Rich, color me impressed. Did you do most of the work creating your system on your own? With a setup like this I assume you are controlling both heat input and cooling input? To reduce steam input do you have some type of variable valve or do you just let the PIDs intermittently cycle the valve open/shut?

I think anything resembling true un-attended automation will have to wait for my next still build! :)

Yes for the steam heated stills we use a 3 stage modulating steam valve, that provides steam control at 0%, 25%. 50% and 100%. Butin reality it seems to mainly use the 25% and 100% settlings, due to the thermal mass of the pot, the temp does not change much once your on the boil.

For gas, we use a 4 stage modulating valve. Fully proportional valves (usually motorized or stepper motor controlled, I have found to be problematic and offer little benefit, as they are $$$$$.

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