T500 Boiler Temperature Control on Reflux

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momchenr
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T500 Boiler Temperature Control on Reflux

Post by momchenr »

Hey gang, hope this is the right place to post this. I have an idea and wanted to run it by the group.

I have the T500 boiler and the Copper Condenser Column. As you know, the way this still works is by controlling the temperature of the output cooling water, between 55C and 65C. I've been dicking around with the PID controllers and I think I could rig up a system that would...

- Monitor the output cooling water temp
- Use the PID controller in cooling mode
- Use an SSR to open/close a solenoid valve on the cooling water

I think this would work, but it would mean bang-bang start-stop of the cooling water instead of steady flow. Modulating valves seem to be very expensive.

What are your thoughts?
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Re: T500 Boiler Temperature Control on Reflux

Post by Pikey »

Hi, Perhaps you could answer a question about the t500 if you don't mind ?

If you leave the lid off completely and put a few pints of water in the boiler, will it actually boil the water, or does it stop just short of an actual boil ?

Now back to your question. The Coolant management still - which yours is, basically requires an analogue type of water control. Fiddly though it may be, your water temperature should be kept as even as possible by adjusting the flow. switching on and off will disrupt the flow, allow the coolant to get too hot, switch on again, allow the coolant to get too cold and cycle through that process. I believe there is a few seconds delay before an adjstment to the flow registers on the output water and frustrates new users by continuin to change after the adjustment has been made.

I would say that this modification is unlikely to succeed in the way you hope.

atb
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still_stirrin
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Re: T500 Boiler Temperature Control on Reflux

Post by still_stirrin »

Like Pikey said, the only way to regulate a CM reflux still is by "proportional control" of the coolant, and of course, the heat input. It sounds like you need a flow control valve, not an on/off solenoid valve. Solenoids are better at maintaining a liquid level, not proportional control.

If automation truly is your desire, then shop for a proportional flow control valve ($$$).

Another possibility would be to regulate a pump motor with the PiD. Use a water reservoir and a recirculating pump, regulating the speed of the pump to manage the flow rates.
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Re: T500 Boiler Temperature Control on Reflux

Post by Pikey »

I've thought about this a little more momchenr. I suppose if you set your temperatures very close together, then the over-runs might stay in that 55-65 band the manufacturers insist is the right band. You could test this by manually switching the tap (faucet) on and off by hand for a run and see how the cooling water performs and to find the right temperatures to programme. However, your abv will vary - low temperature higher abv, high temperature lower abv. We generally strive for consistency and oscillating temperatures are not a good thing. At least if you do it by hand for a while, you will be able to know better what to expect without the expense and bother of making a controller up.

Now if you are going to go this path, be absolutely sure to obtain a solenoid which is guarateed to fault OPEN - so the water flow is high if the electronics go down - although if one of your pieces of silicon fail giving a "Closed" instruction, that could be a Catastrophic fail from a safety point of view.

A failure of the cooling water supply is one of the main failures we dread and why we always have the rule "Never leave a still unattended" - No cooling water leads to ethanol gas being vented into the air surrounding the still. If that is in a room, shed or garage, well ethanol gas can be used to run engines. It's explosiveness is in the same league as petrol (gasoline) - :shock:

In conclusion then - we have the "Unattended rule" so if you have to be with the still anyway, then it shouldn't be a major hardship to correct the temperatue by hand occasionally.

IF your intention is to leave the still unattended, letting this little "do-ins" look after it for you - You are going down a dangerous route of which we cannot and do not approve. You would be putting at risk not only your own life, but those of anyone else around.
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Re: T500 Boiler Temperature Control on Reflux

Post by NZChris »

You might get away with an on off solenoid valve if it is feeding into a reservoir with a surface area over a square foot. The reservoir would smooth the supply to the condenser.
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Re: T500 Boiler Temperature Control on Reflux

Post by RedwoodHillBilly »

still_stirrin wrote: Another possibility would be to regulate a pump motor with the PiD. Use a water reservoir and a recirculating pump, regulating the speed of the pump to manage the flow rates.
ss
This is probably the easiest and cheapest way of doing what you're trying to accomplish.
Last edited by RedwoodHillBilly on Sat Jun 24, 2017 6:01 am, edited 2 times in total.
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skow69
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Re: T500 Boiler Temperature Control on Reflux

Post by skow69 »

Sounds like you are making a buzzer.
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Ma Flodder
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Re: T500 Boiler Temperature Control on Reflux

Post by Ma Flodder »

Pikey wrote:If you leave the lid off completely and put a few pints of water in the boiler, will it actually boil the water, or does it stop just short of an actual boil ?
It will definitely boil the water. It's also sold as a crab cooker, and I use it to cook water to get rid of chalk and chlorine in tap water before I use it to blend my final product.
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Re: T500 Boiler Temperature Control on Reflux

Post by Saltbush Bill »

It wouldn't make a very good boiler for a still if it didn't boil things would it ?
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Ma Flodder
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Re: T500 Boiler Temperature Control on Reflux

Post by Ma Flodder »

I don't think it needs to boil water (it does!) to work as boiler for a still as the boiling point for an ethanol/water mixture is lower. There's a protection to make sure it doesn't boil dry, but that kicks in at a higher temperature.
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Re: T500 Boiler Temperature Control on Reflux

Post by Pikey »

Saltbush Bill wrote:It wouldn't make a very good boiler for a still if it didn't boil things would it ?
I seem to remember on another thread a while back, you said you had started with one of these and was rather hoping you'd confirm that it will boil water. :)
Ma Flodder wrote:I don't think it needs to boil water (it does!) to work as boiler for a still as the boiling point for an ethanol/water mixture is lower. There's a protection to make sure it doesn't boil dry, but that kicks in at a higher temperature.
To get the last of the ethanol out of the wash - yes it absolutely DOES need to go to 100C or 212 F - But I understand there is an issue with allowing the temperature at the head of the column on the T500 to rise above 85C because of the synthetics. I'm not at all sure that you could have the wash temperature at 100C (212F) and still keep the head temp below 85C :?
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Re: T500 Boiler Temperature Control on Reflux

Post by Klein »

They sell a pump that will keep the water pressure consistent. You would be better off using that and the needle valve that comes with it. Much easier and should not have to mess with the valve as much compared to say a well with changing water pressure.
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Re: T500 Boiler Temperature Control on Reflux

Post by Klein »

I had a gravity system for a few test runs (It worked) but moved to a better setup (keg) I would recommend (but I have not used it myself) the pump instead of using gravity as it is just not worth the effort in the end.
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Ma Flodder
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Re: T500 Boiler Temperature Control on Reflux

Post by Ma Flodder »

Klein wrote:They sell a pump that will keep the water pressure consistent.
It's called the "Water flow regulator" and it works fine. Although it's a bit expensive. Temperature doesn't change more than 1 degree C, I try to keep it at 56.
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Re: T500 Boiler Temperature Control on Reflux

Post by petersabbath »

This is how I iron out the bumps in water supply and temps
Run things from the front of the house hose and a fuel hose clamp from the auto shop
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