Temperature control (Next Project)

[Opus 27]

Having finished our alternative head for the Super Reflux we're now looking at boiler temperature control in place of the power controller we previously used. It's based on a PID controller and the components are shown in the photo below. I'll post as it progresses along with photos as appropriate. We'll itemise the costs as the build moves along.

Opus

[Icefever]

I've made a pothead to fit onto the T500 boiler a while back but never done anything about temp control...so I'm going to watch this build...can we have a parts list please

[Capt-Cudellez]

Hi Opus 27, From your post, it sounds like you're going to try and control the boiler temp. You cannot control the boiler temp.

The wash will boil at a temperature dependant on how much water, alcohol, and hundreds of other compounds are in the solution. This will constantly change as you remove more of the alcohol and other compounds as you distil.
So the wash will initial boil at a lower temp, then will rise as the distillation progresses getting closer to 100oC.

Think about it this way, If you have a pan of water on a small camping stove and bring it to the boil, it boils at 100oC, if you stick a 5KW element into it, it still boils at 100oC, putting more power in or controlling how much power you put in does not change the temp that the liquid boils at.

Maybe I have picked you up wrong, can you elaborate more on your project.

[Opus 27]

Hi,
We are not trying to control the boil temperature as such, what we are doing is setting a temperature which will then control the amount of power going into the element at that point in time. As the alcohol comes off we are then altering the set temperature on the controller in set stages. These stages are governed by the flow of the product we are seeing and what is happening on the dial thermometer in the vapour stream leaving the head.

Now for some quick photo's

The first photo is the connections on the back of the controller if you are doing this with a PT100 temperature probe you need to tie 10 and 11 together the single coloured wire on the probe goes to 10 with the remaining two common coloured wires going to 12 and 13.



The completed box with leads switch etc, longer term we will also add an audible alarm option



XLR Plug attached to end of PT100 Thermocouple



XLR Socket in side of case for Thermocouple



SSR 25A Relay to control heating element



Temperature reading from probe (PV Process Value) against Target Value (SV Service Value)



Duty Cycle displayed in SV location against PV reading, so in the image the element would be powered at 100% for 58.1% of the time (eg 5.8 seconds in every 10 second, although the controller and SSR switch at a higher rate than this)



Thanks for looking, we have also completed a run with the new controller which we will post as part of the cornflake thread.

Regards
Opus and Son

[Opus 27]

Firstly here's the price list for the project;
TA7-SNR Controller + 25A SSR + PT100 Probe
(3 items sold as a bundle) £29.99

Extension Lead £6.80

Waterproof Box £7.99

Glands X 2 £7.78

XLR Chassis Socket £3.19

XLR Plug £3.19

Heat Sink £6.51

Switch £0.40

Total £65.85

Now the first run.
The intention of this project was to gain a better control of the heat source.
This is how it went,
We found firstly that we needed a wash temperature of 195 F to get sufficient energy to move the vapour to the top of a 1000mm column with no packing and no coolant water in the column. At 190 F we had total reflux just short of the top.

With temperature then up to 198 F we had a steady run for quite a bit of Heads.

We continued tweaking The temperature in 1 degree steps to see if we could calculate where the three basic cuts would come.

Throughout we collected the product 100 ml at a time, smelling and tasting each one.

We stopped at 35% ABV and we were using a temperature of 206 F in the boiler.

When each of the set temperatures were reached and heating levelled out consumption was reduced to 8% at the lower temperatures and by 30% to 50% at the higher ones. The full load of the element is 1400 Watts.

We now think that we can set 3 predetermined temperatures to complete a run which would give us approximate indications of cuts. We would still continue our normal practice of collecting in 250 ml flasks for tasting and blending.

I think we have achieved a significant reduction in electricity consumption which was the ultimate aim.

Hopefully some of this makes sense. Comments would be appreciated.

Opus

[ant]

Yes, it makes perfect sense. You want just enough power to maintain a temp that will just boil off the fraction you are trying to collect; heads, hearts or tails. The benefit is more precise use of power and a certain flexibility in that if you walk away while collecting heads it should not overshoot into hearts, or hearts into tails while your back is turned.

It is not that different from using the still head temp control of the heaters.

So how has that worked out over time?

[Opus 27]

Truthfully Ant, it's not that successful. We found we had to keep tweaking the temperature in the boiler to maintain temperature in the column. As the quantity of desirable spirit in a given range slowly reduces then more effort is required to keep the column from crashing.

It's now been assigned to one of our mash boilers so it's not a complete loss.

Opus

[ant]

Well nice theory and thank you for the honesty. You could just try moving the temp probe to the head of the still. Might find it needs a lot less tweaking that way but achieves the result you were looking for.