Electronic control of Semi flooded state

[zukram]

I could'nt find anything about this, so I think a thread about it migt be in order.

I've read a lot about semi flooded state, so I decided to try it. As many others I realized that it was a bugger to keep running stable.
I figured that the pressure in the pot should be proportional to the liquid pillar in the column plus an equally proportional pressure drop from the packing. Of course the pressure drop in the packing is proportional to vapour velocity, but nevertheless proportional.

Therefore there -should- be a given pressure for any given liquid level in the column.

So I built a PID controller using SSR and a pressure sensor, and of course a pot temperature sensor, just because it's nice.

Anyway, it worked perfectly after som tuning of the PID. I can control the liquid column level within 10mm or so by pressing a button.

That's very nice.

But given this control I also noticed something strange. It all worked perfektly, head separation was much more effective than before and I got into hearts after about halft the usual heads amount. Then I could run the column with almost double my normal takeoff producing 94-95,5% (accouring to my glass meter) for about the normal hearts amount.

But then it stopped. Temperature in the column rose above my setting for the E-arc and the takeoff valve shut.

The temperature did'nt fall again, until I more or less emptied the column from liquid and started again.

Anyway, this method of power control should also work well for plates or sieves (I'm planning on building a sieve-tree), to control how much liquid there is in the column.

Some more tuning and experimenting is of course needed, maybe I have to move the sensor for the E-arc system a little upwards, and maybe it would work better if the liquid level is below the sensor, in that case It would probably be better to move it a little higher.
Also as the alcohol is taken out of the pot, the density of the mesh increases causing the level in the column to sink a few inches, that could problably be compensated for by using the pot temp sensor, but ut works pretty well by just taking a look in the sight glass now and then and increase the pid target value.

I'm currently using thermistors, but I have a bunch of PT1000's and I plan to upgrade to them and possibly add a few more, just to see what happens in the colum. Maybe an IR thermometer would be good come to think about it.



I'm not sure if this is the best category, but anyways I wanted to share my experiences and maybe get a few thoughts and comments.

[drmiller100]

What percentage is your wash before and after a run?

If you are starting 10 percent and running down to say 3 percent there is a significant difference in water to alcohol percentage. Due to the difference in latent heat of vaporization as you run the energy required to boil the water becomes more and more expensive meaning you will have a lot less overall vapor going up the column. This is maybe why the level lowers.

The temperature rise I'll think about. If you let the colum drain off and restart does it continue producing etoh?

Why flooded rather than just get better packing material?

[Salt Must Flow]

EDIT: Nevermind me, I'm a retard. He said PRESSURE and I assumed temp.

It stopped because you can't control a still by temperature. PID controllers are just precise thermostats to maintain a precise temperature.

You control a still by varying the amount of power input. That's why we use variable power controllers.

You can either build another controller, a variable power controller, or convert your existing controller into a variable power controller. I personally prefer the Auber Instruments DSPR400 because it functions as BOTH a variable power controller and a PID controller. It has many other smart functions, temp alarms and other settings I may never use. The DSPR400 would be a simple swap with your existing PID controller and be a great upgrade without having to build an entirely separate controller.

[Salt Must Flow]

EDIT: Nevermind me, I'm a retard. He said PRESSURE and I assumed temp.

1. For those that 'think' that you can control a still using a PID controller ... you have to set your temp. I have a 5500W element.
2. The PID controller will fire the heating element at 100% power. That's 5500W input of power, WAY too much power and will terribly disrupt the equilibrium of the column.
3. Once the vapor temp reaches the set temp, the PID controller will turn the element off and may pulse the element rapidly to maintain that exact temp. The distiller notices that the take-off just stops and never starts again.
4. To force take-off to start again, you have to bump the set temp up. This cycle repeats.

You cannot operate a still using a PID controller. During a spirit run with a reflux column/still the vapor temp essentially remains the same throughout the entire run. It only fluctuates within a few 1/10th degrees F. During hearts it pretty much remains the same right up until tails hits.

That Auber controller for instance allows you to control your power input by 1% increments from 0%-100% power. It's precise and repeatable.

[shadylane]

If I was going to use electronic control on my reflux column it would be based on boiler pressure.
From experience, I know somewhere between 4"and 6" of WC is the sweetspot.
Having said that, automation has no sense of smell nor taste.

[zukram]

I'm not controlling by temperature, I'm controlling by pressure.

That's the whole point

Maintaining an even pressure in the pot also maintains a level of flooding (within say an inch).

The reason for trying this was that running semi flooded seems to have some benefits (which it does) and by using a PID on pressure fixes that problem. The benifits were obvious until the column temp (70cm from the top) started rising. Higher ABV, better taste at double the output.

If I altered the set value for the output valve quality rapidly decreased. That's why i drained the column and ran the more traditional way for the rest of the run.

The temperature only controls the output valve. (LM). The condenser controls the output rate. (CCLM).

Of course the regulation is not on/off, it's PWM with one second period. It's not a bought product, that would'nt do the job, i built it and programmed it from scratch. I'm pretty happy with the power controlling algorithm, very smooth from 0-9kW. It can run temperature PID too, but I added that just for fun.

The wash was ca 40% starting (I always do a strip run).
I measured the wash when the flooded state stopped working, and it was around 10%. After draining the column it produced maybe 3 more litres of good spirit around 93%.

[zukram]

What percentage is your wash before and after a run?

If you are starting 10 percent and running down to say 3 percent there is a significant difference in water to alcohol percentage. Due to the difference in latent heat of vaporization as you run the energy required to boil the water becomes more and more expensive meaning you will have a lot less overall vapor going up the column. This is maybe why the level lowers.

The temperature rise I'll think about. If you let the colum drain off and restart does it continue producing etoh?

Why flooded rather than just get better packing material?

Actually the amount of vapor entering the column is pretty much constant this way. Surprisingly though the power added did'nt increase much. I would think that it should. But to be honest I was more observant of other factors so I might have missed that it increased.

Yes it continued producing. Not as fast, and slightly lower ABV. I'm still pretty pleased, a spirit run must have been 2-3 hours faster.

[zukram]

If I was going to use electronic control on my reflux column it would be based on boiler pressure.
From experience, I know somewhere between 4"and 6" of WC is the sweetspot.
Having said that, automation has no sense of smell nor taste.

It's the person programming the automation, and running the automation who's responsible for the taste

[zukram]

I also have a temp alarm, the pot temp is a good way of indicating that the run is over, so I plan to let the controller shut down when reached a certain temperature. I think that'll have to wait until the PT1000's are in place though. That's not important.

The idea I wanted to share was the possibility to control flooding of the column, and it works perfectly.

Why it just works down to 10% ABV is somewhat of a mystery to me though. Maybe flooding part of the column is a solution, I'll try that the next run. Or running full column until the temp rises, and then dropping the pressure to 1/2 or something like that letting the E-ARC measure vapor temperature rather than liquid temperature.

I imagine it could also work better with another packing, or with plates. Scrubbies is not ideal especially since the column is 3,5".

[Salt Must Flow]

I'm not controlling by temperature, I'm controlling by pressure.

That's the whole point

Maintaining an even pressure in the pot also maintains a level of flooding (within say an inch).

The reason for trying this was that running semi flooded seems to have some benefits (which it does) and by using a PID on pressure fixes that problem. The benifits were obvious until the column temp (70cm from the top) started rising. Higher ABV, better taste at double the output.

If I altered the set value for the output valve quality rapidly decreased. That's why i drained the column and ran the more traditional way for the rest of the run.

The temperature only controls the output valve. (LM). The condenser controls the output rate. (CCLM).

Of course the regulation is not on/off, it's PWM with one second period. It's not a bought product, that would'nt do the job, i built it and programmed it from scratch. I'm pretty happy with the power controlling algorithm, very smooth from 0-9kW. It can run temperature PID too, but I added that just for fun.

The wash was ca 40% starting (I always do a strip run).
I measured the wash when the flooded state stopped working, and it was around 10%. After draining the column it produced maybe 3 more litres of good spirit around 93%.

You clearly said pressure. I'm a retard. Nevermind me.

[drmiller100]

I also have a temp alarm, the pot temp is a good way of indicating that the run is over, so I plan to let the controller shut down when reached a certain temperature. I think that'll have to wait until the PT1000's are in place though. That's not important.

The idea I wanted to share was the possibility to control flooding of the column, and it works perfectly.

Why it just works down to 10% ABV is somewhat of a mystery to me though. Maybe flooding part of the column is a solution, I'll try that the next run. Or running full column until the temp rises, and then dropping the pressure to 1/2 or something like that letting the E-ARC measure vapor temperature rather than liquid temperature.

I imagine it could also work better with another packing, or with plates. Scrubbies is not ideal especially since the column is 3,5".

35 inches of scrubbies? That isn't enough.
36 inches of 12 mm marbles is enough.

[shadylane]

You clearly said pressure. I'm a retard. Nevermind me.

+1 on your correction, everyone makes mistakes.
Ya should get 10 out of jail points for honesty.

[zukram]

35 inches of scrubbies? That isn't enough.
36 inches of 12 mm marbles is enough.

Diameter: 3,5" 89 mm
Lenght: 60" 1500mm

I've never considered running with marbles.
I've considered SPP, bubble plates and sieve plates. Or just perforated plates, but I don't fancy drilling that many holes and perforated stainles is really expensive if you have to buy an entire sheet.

Would'nt marbles have trouble holding the liquid? If I still want to run it semi flooded ?

[zukram]

It looks like this

[zukram]

If anyone want's to try this, I can provide a schematic and code.. If you can stand swedish comments
This setup is good for 16 A. Also 9kW is hardcoded.. Easy to change though.

It has 3 modes, manual power control.
Temperature PID control.
Pressure PID control.

It should work fine for 60Hz. And of course, you choose the SSR's depending on Amps.
In retrospect i should have orderd 40A or 60A SSR's, it seems they last longer.

[Saltbush Bill]

I've considered SPP, bubble plates and sieve plates. Or just perforated plates, but I don't fancy drilling that many holes

If your after neutral, plates, caps or perforated are not the way to go, stick with packing SPP , rocks or marbles, personally I prefer copper mesh.

If anyone want's to try this,

No thanks , not even a bit interested , I cant see the point of complicating what is already a very simple process.

[zukram]

No thanks , not even a bit interested , I cant see the point of complicating what is already a very simple process.

The point: Double production rate, slightly higher ABV. And besides, when the PID is tuned in running is very easy, I'd say easier than just running E-arc or manual.

Another point of course is curiosity. That's a big part of the hobby for me, trying new stuff and building cool gadgets.

Besides this IS the "Reseach and Theory" part of the forum

[kennstminet]

Zukram
I‘m interested in your project and see your point.
I always aim to run my column near the flooding point.
Unfortunately this sweet spot changes after i had removed the SPP for cleaning. Depending on how tight I stuff the packung, the flooding happens at different power levels.
Not a serious problem, but a noticable issue.
I‘m curious as well, have an electronics background and love to play around.

[tjsc5f]

I'm interested in the pressure sensor used, do you have a link for it?

[LWTCS]

At any point during your run is the PID turning off the power to your heat source? Even for a split second?
Or does it continuously modulate with no interruption of input what so ever?

The thing is that within the context of what we do heat always = pressure. Though pressure doesn't always = heat.

And as the alcohol is rendered out of the kettle, kettle temps have no choice but to increase as the boiling point of the constituents in the kettle changes.

I can see how managing pressure on a continuous system would be beneficial. But I'm having a hard time understanding how using kettle pressure with PID to govern heat input is any different than using temperature with PID?

But for sure I'm a fan of the journey.

[zukram]

At any point during your run is the PID turning off the power to your heat source? Even for a split second?
Or does it continuously modulate with no interruption of input what so ever?

The thing is that within the context of what we do heat always = pressure. Though pressure doesn't always = heat.

And as the alcohol is rendered out of the kettle, kettle temps have no choice but to increase as the boiling point of the constituents in the kettle changes.

I can see how managing pressure on a continuous system would be beneficial. But I'm having a hard time understanding how using kettle pressure with PID to govern heat input is any different than using temperature with PID?

But for sure I'm a fan of the journey.

It's PWM controlled using 100 half periods, so with 50Hz it's 1s period. Longer period turned out too long due to too low heat storage capability in the elements causing pulsating in the boiler. Also I have 3 elements and use an offset between them, so they divide the period by 3 to make it even smoother.

The benifit is that I keep a constant level of flooding in the column without having to manually check it every 3 seconds.

I suppose it would be possible to maintain a more or less constant level in the column using temperature control in the pot, but this is easier.

[zukram]

I'm interested in the pressure sensor used, do you have a link for it?

https://www.aliexpress.com/item/1005005 ... ry_from%3A

[drmiller100]

No thanks , not even a bit interested , I cant see the point of complicating what is already a very simple process.

The point: Double production rate, slightly higher ABV. And besides, when the PID is tuned in running is very easy, I'd say easier than just running E-arc or manual.

Another point of course is curiosity. That's a big part of the hobby for me, trying new stuff and building cool gadgets.

Besides this IS the "Reseach and Theory" part of the forum

I completely understand wanting to try things and experiment.

I question your claims. A good column is ultimately limited by the math of energy.
If you doubled your output by running it flooded you didn't have a good column to begin with.

Ultimately you did indeed figure out how to maximize boiler energy and I applaud you for that. I'd use it to run just under flooded.

Also you can minimize reflux rate by going 4 inches from the top of the packing and measuring temperature to control reflux.

Also for giggles go down in the middle of your packing and measure temperature at different points across one vertical level. You can measure the stove piping.

[zukram]

I completely understand wanting to try things and experiment.

I question your claims. A good column is ultimately limited by the math of energy.
If you doubled your output by running it flooded you didn't have a good column to begin with.

Ultimately you did indeed figure out how to maximize boiler energy and I applaud you for that. I'd use it to run just under flooded.

Also you can minimize reflux rate by going 4 inches from the top of the packing and measuring temperature to control reflux.

Also for giggles go down in the middle of your packing and measure temperature at different points across one vertical level. You can measure the stove piping.

Well. you are probably right about the column. I know scrubbies are anything but optimal, especially when larger than 3".
I do want to use SPP, but it's an investment in time to make, and it's not clear to me what dimension would work for 3,5" column. I made a batch of 8mm spp using 0,8mm welding wire, that did not work at all well. Probably 0.8mm was to coarse, but that's for another thread (or any of the 100 spp threads). I think maybe 7mm diameter and around 0.4-0.5 mm wire would work. But everybody seems to have a different view on SPP so I hav'nt got around to do it.

I wonder if the reason I did'nt get any output when wash was under 10% might have been that the "bad stuff" actually just stayed in the column, blocking new alcohol from entering. somehow. If it happens next run, I think I'll try to lower the liquid level periodically. That way the bottom layer will drizzle out, and leave room when I rise the flooding again.

The root cause is probably a packing problem.

I actually ran it almost exactly 4" below the top, maybe a little less.

[zukram]

Still waiting for the mash to clear up.. sigh.. I hate waiting for mash...

[zukram]

I've ran it one more spirit run now and I must say that it works very very well.
I ran it at a lower pressure this time for the entire run.
One thing I noticed was that the E-arc LM worked better than I've experienced before.

It might be due to the power management regulating down sligthly as the valve closes and reflux increase. Or something. Anyway. It worked very very good. I still need to tinker with the PID parameters to get it to dial in faster, and more reliably, but, when I had it regulating, it was just smooth sailing.

Still there are some bugs left, mainly becaus I integrated column valve control in the same box for convenience. Less cables to trip on too


I've upgraded the installations a bit. A better I2C controlled keypad, a couple of 3dprinted boxes and heatsinks for the SSR's. I think I'll also add a fan for the SSR's they heat up the bottom plate and with it the air int the boxes.

I still have som issues with the valve, it's not that well shielded so it screws up the i2c bus when the internal switch breaks, but I managed to handle it with a watchdog in software. I actually put a transistor driver for VCC to the i2c-bus components, so it breaks the power on timeout resetting everything. But I'll fix the bottom problem when the next order of capacitors arrives.

[Yummyrum]

Great project and thanks for sharing zukram.
It is always nice to see projects get off breadboard's and end up in boxes.
Yes please share code .
Also a quick schematic would be nice too .

I’ve been working on a Burstfire controller rather than the time proportional you have used , so I am curious about your zero crossing detector circuit . Looks like you have used an optocoupler ? Which type ?

viewtopic.php?p=7787168#p7787168

I do find your project interesting as I suffer from quite severe power fluctuations through the day and regulating power is my aim . You are doing it by measuring Column pressure whereas I was looking at measuring the mains voltage and adjusting power to compensate .
Your method achieves the same effective out come .

[tjsc5f]

I suffer from quite severe power fluctuations through the day and regulating power is my aim . You are doing it by measuring Column pressure whereas

I think something like this would suit you well https://www.finglai.com/products/relays ... 0YB-F.html

I've been using the open loop one successfully for several years now with no issues (my mains voltages are pretty stable), but would certainly give the closed loop one a shot.

[tjsc5f]

One thing I noticed was that the E-arc LM worked better than I've experienced before.

What does your E-arc LM head look like? Something out of Riku's book?

[zukram]

No, not really. Its a combination of the "condenser control liquid management" someone here posted a long time ago, and an E-Arc LM control system. By moving the condenser in the head I can control output like if I had a needle valve, and the valve closes on temperature. But I suppose the principle is the same. The liebig is just to cool the product, it's not really needed, but i had one from an old labmaster ripoff.

The original design had the same diameter on the head as the column (3"), but I improved the design by going from 3,5" to 2" which makes it more precise when moving the condenser in and out. Only issue with the head is that I made the copper spiral just a bit too short, but it works fine mostly. It limits my power usage to about 6-7 kW when doing stripping run. It would be nice to be able to run it on 9kW.

Someday I'll build a dedicated stripper head with just a big condenser, but it work. You can see that I have an output in the end of the head as well. When stripping, i turn the condenser tube the other way, the valve pointing upwards. That way I get more speed, but the output is warm.

Yesterday I also added a boil-up-feature, so I can set a value for pot temperature and the regulator will run 9kW until it's reached and then switch over to PID-control. Just for convenience. Also I have a pot-temperature alarm, that I'll set to the same temperature. That way I minimize risk for overboil. 9kW is a LOT .. but I don't like waiting.