Lester's VM/LM Build

[Danespirit]

I need some help guys.

I built my still according to the dimensions shown in this pic (LM port, condenser & VM valve were omitted for clarity):

Lester's VM & LM.jpg

I wanted to try it out before proceeding any further so I ran this still thing with just water in the boiler.

The LM system works fine and I can vary the take off rate from zero to almost a stream. Reflux condenser & needle valve is working well.

But I can hardly get anything out of the VM branch, about 1 drop every 5 to 10 secs. I don't have a cover at the top so I (loosely) stuffed a rag in there, just to force more vapors into the VM branch. I got 1 drop every 2 secs that's all. Even if I remove the sliding valve I still get very little output.

Is this performance to be expected from a VM with just water in the boiler? Will I get more output when I start distilling low wines?

I would like to modify now if needed, before I go into cleaning runs.

Thanks in advance for any help.

As you are just running water, it will behave very different from what it does in an acctual distilling operation. If you load your boiler with wash, it will be a mixture of water and alcohol. Those compounds have different boilingpoints. Run some low wines thru your still, and you will soon notice the difference.

[Lester]

Thank you Danespirit! I will do as you say.

[Lester]

I cleaned my LM/VM column today. Steamed it for 30 minutes using water, rinsed, then steamed it with vinegar for 30 minutes then rinsed.

Alcohol sacrificial run: I charged the boiler with >2 liters of 33% ABV (from my previous cleaning run on the pot still) got a steady temp of 81.1*C (looks like my thermo is off, yes?) for more than 30 minutes so I opened the VM valve......... and nothing came out. I waited and waited and finally decided to just take product out from the LM port. I got a steady stream until the temp suddenly went up to >96*C so I stopped. I got less than 1 liter out.

After cooling, I measured what I got from the LM port and it was 81% ABW (84.4% ABV). Not so great but then it's just a cleaning run.

Packing material: REAL lava rocks (very porous, they float on water) about 1" diameter
Cooling water temp after the reflux condenser is ~60*C
2 layers of 1/4" foam insulation on the column
Ambient temperature: 33*C
Total running time: 1.5 hours

Cooling system works well. I started with 27.6*C water and ended with 27.5*C water. Had to add about 2 liters to make up for the lost water due to evaporation.

I am happy with the LM output but I am still stumped as to why I'm not getting anything out of the VM port. What am I doing wrong?

[Lester]

...... or maybe I only have tails in my low wines? I must try this soon with low wines from a stripping run of Birdwatcher's. My wash is at 12% now, 36 liters total but my boiler can only hold 26 liters so I'll have to do stripping in 2 batches.

......or should the Birdwatcher's go directly to this VM/LM column without first stripping on a pot still?

It is very possible that my vapor speed is too high. That, plus the tiny 19mm port without the benefit of the added volume of a 2" tee might make the vapor miss the port entirely and head straight up to the reflux condenser. I'm just guessing here.....

[YHB]

Lester,

Did you eventually use a piston type take off that you were talking about? or is the take off it just a straight tee?

[rad14701]

Lester, it sounds like you either have a structured packing issue or you need to crank up the heat... Regardless of the composition of the boiler charge the temperatures at the top of a reflux column should be the same for a specific rig configuration...

[Danespirit]

Lester,

Did you eventually use a piston type take off that you were talking about? or is the take off it just a straight tee?

This could be the reason..

Another issue is your packing. Is it probably to hard packed?

Last but not least...have you tried to crank up the heat a bit?

I would prefer to do at stripping run in a potstill first. This way you will get rid of the yeast and impuritys. Then go for a spirit run in your VM.

And...a VM makes a kind of "autoshutoff" if the ethanolcharge in the boiler gets too low.. then you will get no output either.

Hope it helps..

[Danespirit]

Ooops! Sorry i was posting while Rad also was giving an answer to this subject...

[Lester]

YHB,

I did not use a tee. The 3/4" tube's end was flared and soldered directly onto the side of the 2-1/8" tube at a 90-deg angle. I used a piston valve.

Rad,

I did try going for maximum heat but still no output from VM. I am using a 2-ring propane burner about 6" diameter.

I don't understand how the packing can affect the VM take off. I was thinking that the packing was responsible for the lower ABV that I got, not the loss of output at the VM port. Can you explain further?


Danespirit,

I think it is very loosely packed since I have large pieces in there, average diameter of packing material is 1".

Maybe I don't have enough Ethanol in the boiler.


All,

Do you think that I should use a tee? The way I built my VM I lost the sudden change in cross-sectional area in a tee, which would result to a slower vapor speed right at the VM port. A typical VM is shown at "A" and what I have made is shown at "B".

What do you guys think? I can modify what I made to make it look like what is shown at "A".

Thanks for all your replies!

[YHB]

I have seen posts on various boards from folks with a similar problem and who have overcome it by adding a scrubber or two between the VM take off and the first slant plate.

The theory being that the restriction the scrubbers create causes a slight pressure increase that will encourage the vapour to look for alternative routes, ie take a right turn down the VM take-off.

Before you start ripping your column to pieces it may be worthwhile giving this some thought.

Brian

[Lester]

I have seen posts on various boards from folks with a similar problem and who have overcome it by adding a scrubber or two between the VM take off and the first slant plate.

The theory being that the restriction the scrubbers create causes a slight pressure increase that will encourage the vapour to look for alternative routes, ie take a right turn down the VM take-off.

Before you start ripping your column to pieces it may be worthwhile giving this some thought.

Brian

Thanks for that idea Brian! From your explanation I understood what the additional scrubbers are for.

I don't have scrubbers so I made a flat eliptical plate with a single 10mm hole to act as a restrictor plate. This sits right on top of the upper slant plate and retains that position while I run the still.

The VM port is working now after I placed the plate but the output doesn't stop even well into the tails. I think I need to make the 10mm hole a lot bigger.

[YHB]

Lester,

I am pleased for you. I think you are nearly there.

How does the slide valve work? Can you accurately control the VM take of rate with it? or is it more of an all or nothing options?

Brian

[Lester]

Lester,

I am pleased for you. I think you are nearly there.

How does the slide valve work? Can you accurately control the VM take of rate with it? or is it more of an all or nothing options?

Brian

Brian,

Your slide valve works great! I can go from zero to a full stream and any other setting in between. I still need to make a micrometer for it so I can easily make small incremental adjustments.

I just need better packing material and I think I can hit >90% ABV with this 4-ft column. I already have tiny pebbles (10mm diameter) so I will try those next time.

For my first distilling run I charged the boiler with 12% wash (lava rocks packing) and I was able to get 81% ABV. Now I understand why it is preferable to start with 40% low wines on a reflux still: Among other things, it is so much easier to hit 95% ABV. I still have a lot to learn but I'm getting there.

[YHB]

Lester,

Get the packing right and you can get 95% from a 10% wash in one run.

I get 95% with only 12" of packing, tastes like S**T but its 95%, with this length it is hard to get good separation and everything gets mixed in. Add a two foot packed extension and everything is OK = so with your four foot column you will be hard pushed not to get 95+%

I use stainless steel scrubbers from the Pound Shop, I know you have said that you cannot get them locally, but keep your eyes open.

In the meantime I will follow your trials using stuff that you can pick up off the floor for free, I like that concept.

Toodlepip

[Danespirit]

I have seen posts on various boards from folks with a similar problem and who have overcome it by adding a scrubber or two between the VM take off and the first slant plate.

The theory being that the restriction the scrubbers create causes a slight pressure increase that will encourage the vapour to look for alternative routes, ie take a right turn down the VM take-off.

Before you start ripping your column to pieces it may be worthwhile giving this some thought.

Brian

Thanks for that idea Brian! From your explanation I understood what the additional scrubbers are for.

I don't have scrubbers so I made a flat eliptical plate with a single 10mm hole to act as a restrictor plate. This sits right on top of the upper slant plate and retains that position while I run the still.

The VM port is working now after I placed the plate but the output doesn't stop even well into the tails. I think I need to make the 10mm hole a lot bigger.

Now if i understand you correctly,you inserted that plate between the upper slant plate and your reflux condenser?

If this is so, that is why your output doesn't stop before you're well into the tails.

Explanation: The slant plates already represent a restriction/obsticle in the vaporpath, by putting a eliptical plate on top of that you add further "blocking of the vapor". Especially with a hole that is just 10mm in diameter, you are almost "chocking" off the vapors to your refluxcondenser.
Like YHB wrote..try some scrubbers.

[YHB]

Danespirit,

Sorry I do not see that.

The reflux ratio is dictated by the amount of product removed by either the LM or VM take offs.

Close both LM and VM take offs and the column is in 100% reflux otherwise vapour would come out of the top of the column.

Opening the VM to take off say 5% of the reflux must leave 95% of the reflux in the system.

I cannot see the difference between creating a restriction with scrubbers or an orifice plate, maybe I am missing something.

Brian

[Danespirit]

Hi Brian..

You're absolutly correct about the reflux.

It would be no difference between scrubbers and a orifice plate if both had the same flowrate.(would let equal amounts past through)

But vapor and liquid is "lazy". It will take the path of least resistance.

By putting a plate with a 10mm hole in the column, the vapor will take the way out of the 3/4" takeoff instead.

The 10mm hole will cause a Venturieffect. This means the "vapor pressure" in the column (before the hole) is higher. Vapor pressure may not be the correct term.

I am not a scientist at all, so please correct me if my thinking is wrong.

Danespirit

[YHB]

Danespirit

Yes the Scrubbers and the Orifice plate will increase the vapour pressure but to varying amounts, the other variable is how much the VM valve is opened. You can get the same flow rate with a smaller pressure and opening the valve more.

But thinking about this again, it may be the pressure that is pushing the tails through rather than allowing gravity to take over.

Perhaps Lester is on the right track trying to reduce the pressure by opening up the orifice more and reducing the pressure.

I will keep on watching this thread I am enjoying it.

Brian

[Danespirit]

Hi Brian..

Funny how a new build can get our braincells running hot..

You may have a point there...Another ting in my mind is heat.

In the start of this thread, Lester was given the advice to crank up the heat. As i see,he has a rather small boiler attached.
With the plate installed the heatsetting may be a bit overdone by now.

So the problem may be a combination of a to small hole in the orifice and to much heat input,causing the tails to be pushed over.

Lester...the ball is yours to play...

Did the larger hole in your plate work out? And what about the heatsetting?

[Lester]

Instead of a single 10mm hole I now have 3 holes of 10mm diameter. I figured the cross sectional area of the 3 holes would be equal to a single 17mm hole, which is what my VM port is. So now the refulx and VM port are almost equal, same as having a tee in there.

I charged my boiler with 35% low wines, brought it up to a boil then refluxed for 45 miuntes. The lowest temp I got was 79.9*C. I figured it won't get any lower so I started extracting heads at 2 drops per sec. After about 250ml the temp rose to 79.9*C then finally 80.1~80.2*C. I truly suspect my thermo to be off so I figured I must be into the hearts so I opened up the VM valve and collected the distillate. This went on for about 4 bottles of 700ml each. There were several times when the temp went up to 80.5*C so I closed the VM valve and allowed her to reflux some more. In a couple of minutes the temp was back to 80.1~80.2*C so I opened the VM valve again and collected the product. I got about 4 bottles total of what I think are hearts.

The temp was rising and I could not keep it down anymore so I switched bottles with another one labeled "tails". I'm using the LM this time and I hardly got 100ml of tails when the temp shot up to 99*C so I closed the valve for 100% reflux. The temp only went down as low as 85*C so I opened the LM valve again and collected. What I got was not much, about 50ml when the temp rose again to 99*C so I figured I must be out of alcohol by now and shut her down. Total of 150ml of tails is what I got. I know that's very off but my charge was a mix of previously distilled stuff so I don't really know. Maybe I can't smell too well also.

I then measured the alcohol content and these are my readings. (I am still using my crude ABW rig and convert the readings to ABV)
Hearts # 1 (250ml) = 89% ABV
Hearts # 2 (700ml) = 93% ABV
Hearts # 3 (700ml) = 88% ABV
Hearts # 4 (700ml) = 88% ABV
Hearts # 5 (220ml) = 60% ABV
I can hardly detect any odor even at these high % so I am very pleased with my run this time.

What I noticed during the run:
1. Even with my VM valve completely shut I still get about 3 drops/sec from the VM output. I can only conclude that this is due to the reflux falling right on the control shaft of the valve and leaking its way into the VM output.

2. My LM needle valve leaks 1 drop every 7 seconds. I think this is inconsequential so I'll leave it at that for now.

3. My lack of experience in running a still makes me check everything in succession, repeatedly over and over. As I gained more "stilling" time I also gained more confidence. This came about after somewhat being able to anticipate what is going to happen next, and what I should do to correct, if needed.

4. Right now I think I could use more heat. I am at max heat all throughout the run and the output is pencil-lead thickness sometimes, a fast dribble lots of times.

5. I really think my thermometer is off by about 2*C. I will check it against a lab-grade thermo and see what I get. Worst-case I can still use it since I get good enough resolution. The error is an offset error and I can work that out in my head as I run the still.

Meanwhile, take a look at my cooling water flow indicator. Water flows upwards inside a glass tube going up into the faucet. Faucet is closed so water flows downwards on the outside of the glass tube. It looks like the faucet is giving off water out of thin air and it screws up people's mind the first time they see it.

I have placed a tiny "window" right after the LM's needle valve so I can see the drips right up there, not after travelling about 5 feet into the collection bottle. I had installed a glass plate (salvaged from some old spectacles) but it fogs up so I just have an open window right now, no glass cover. I don't think there's a safety issue with this viewing port. (I will post pics of this later)

Overall I am extremely pleased with this column.

Thank you everyone! I could not have come this far without the help you folks provided.

[YHB]

Once in a while I see something here that puts a big smile on my face but today I cannot stop grinning.

Your flow indicator is brilliant - I Love it !!!

If I was you the next thing I would look at is the slide valve. If it is passing 3 drops a second, then when you are pulling of the heads at 2 drips a second then the total is 5 drops a second, on my rig that would be way too much and I would not get the compression that I am looking for and would need to make a much later cut for the hearts.

You may be rights about where the leak is, on the other hand it may be the vapour pressure pushing vapour past the plunger. Do you have enough room to wrap the plunger with PTFE tape? or perhaps make a PTFE washer - similar to the washer in a bicycle tyre pump.

Sorry - Can't stop looking at your flow indicator. you have made my week !!

Toodlepip

Brian

[Danespirit]

I must say...you are a inventor..LOL "flow indicator"...(not soon to be forgotten).

Glad to see it worked out with the orifice.
The amount of product is real good despite the little boiler you have installed.
Now you have to fix the leak at your slidevalve..as Brian pointed out PTFE tape could be a solution. Belive me...it can be your friend in many ways..

4. Right now I think I could use more heat. I am at max heat all throughout the run and the output is pencil-lead thickness sometimes, a fast dribble lots of times.

I don't think you need more heat, "pencil lead thickness" is just fine..

About your thermometer...many of those cheap ones,are crap. You can do a test, holding it in boiling water it should show 100C as this is the boiling temperature of water.
The "window" at the LM takeof you have installed..how do you plan to seal it? Please don't tell us you going to do it with aquarium silicone or the like..
Have fun with your still....and the "flow indicator"

[YHB]

Hi,

Just popped back to have a look at your Tap again.

But while I am here a thought on thermometers.

Do not be in too much of a rush to get rid of yours. Maybe it is not calibrated accurately, but that does not matter. All you need to be able to do is monitor temperature change, which you are doing quite nicely.

When am collecting hearts I stop anytime the temperature rises more than 0.2 Deg C not when it goes past a certain temperature. I bought two matching panel mounted digital readouts and used the more accurate PT100 probes, spending more money than I wanted to. They are both within tolerance of manufacture but give different readings by 1.7 Deg C. I have one on the LM and one on the VM/Pot I ignore the temperature and just watch the changes.

If I were you I would think about keeping the thermometers and spending the money on an Alco-meter instead, I think you will find that more of a benefit.

Toodlepip

Brian

[Lester]

Thanks guys!

Thermo: I recall that I actually checked my temps while doing cleaning runs with water and vinegar. The reading would start off at 100.0*C then slowly climb up up to 102.0*C for the rest of the run. Yes it would still be useable. I didn't know that 1.7*C error is still within spec for these thermos, that's a lot of error! Anyway I will do as you say, watch for the change in temp rather than the actual temp reading.

Slide valve leak: I tried your suggestion to wrap the valve with teflon tape and it seems to stay in place after several repeated slides so yes I think this will work. I will try it out in a few days.

Flow indicator: I can take a big washer with a big hole then drill 2 small holes and put screws on to hold the glass in place. No need to seal because the condensate doesn't form a pool in there, the exit hole is way too large to form a pool out of slow drips. The glass is more of a splash guard.

Brian: In your case with your thermos being off by a large amount (same as mine); how do you know that you can start bleeding off fores and heads? On my column the temp reached 79.9*C (this is the lowest that I got) in about 15 minutes but I waited for another 30 minutes before bleeding off. Can I start bleeding off heads once I reach this lowest temp?

I now realize that it's a fine balance we need to maintain while running this still. If I take product off too fast then the temp will rise and I have to close the VM valve and reflux some more, then the temp comes down again and I can take some product out again. I went through this cycle of open/close VM valve several times because I have not yet found the sweet spot for my column/boiler combination.

[YHB]

Lester,

The specification for my thermometers is plus or minus 1 deg. One is plus the other is minus.

What is the boiling point of water and vinegar? I am sure it is not 100 degC so don't rely on that as a bench mark.

If I am saying the obvious or talking rubbish then forgive me, but the way my brain sees it is that;

The temperature of the vapour does not alter as such, it is the mixture of the vapour that changes, each mixture has a its own temperature. When you see a rise in temperature you are measuring a change in the type of vapour. You are not controlling the temperature of the vapour, you are controlling the type of vapour at the top of the column that the thermometers are measuring.

When the column stabilizes the vapours stack up with the lowest temperature at the top and the highest at the bottom lets call it hearts at the top tails at the bottom. As you take off the distillate the reflux properties of the column will continue and replace the hearts at the top of the column. If you take off the hearts quicker than the reflux capacity of the column / packing can replace it you get the next level down - tails which have a higher temperature hence your thermometer goes up.

I believe that a longer stabilisation / equalisation period gives you a thicker layer of hearts and less chance of depleting it and running into tails. Which is why I believe that I struggle with the short column. The strata of vapours are very thin and I keep pulling the lower levels of undesirable vapour. Tall column, thick layers, take off less than the reflux capacity of the column = nectar.

So in answer to your question, in my opinion, do not start bleeding off the product (or allow it to drip out of the VM) as soon as you reach the temperature you quote, give the column time to build up a reserve of heads behind the valve before you open it. Initially it will save you pulling hearts and throwing good stuff down the drain mixed with the heads, and later on pulling tails into the hearts and spoiling your drink.

Toodlepip.

[Lester]

Brian,

There's no rubbish in your words. All you have given me so far are extremely useful information, and you have always pointed me in the right direction I should take. That alone saved me a lot of time and trouble so no, I don't think that's rubbish at all!

That's a very detailed description of what's going on in the column. After reading what you wrote I now have a better understanding and will keep it in mind the next time I run the column. I kept on reading "compressing the heads and tails" elsewhere here on HD but didn't really understood what that meant. Now I do!

[Just a Biker]

I have been thinking about irregular readings on thermometers in a column. I think one of the contributing factors is the heat of the column walls. Most thermos we use have a metal shaft that is stuck tightly through a hot metal column wall. As the different temperature vapor collects at the top of the column it will also affect the temperature of the column walls. The metal of the shaft conducts that heat to the senor.

Compare that to sticking the same metal thermo into boiling water, the shaft and probe are in the same temperature environment and the measurements are more accurate. But we have our thermos touching a column wall of one temp and vapor bath of another.
I think that is why I see a lot of people saying that their thermo is a bit off. The answer is to understand why it is off. Since the thermo is only guide, just apply a basic offset and you are good to go.

Lester I see you are doing that, I am just offering a possible reason for your irregular readings.

[Lester]

I have been thinking about irregular readings on thermometers in a column. I think one of the contributing factors is the heat of the column walls. Most thermos we use have a metal shaft that is stuck tightly through a hot metal column wall. As the different temperature vapor collects at the top of the column it will also affect the temperature of the column walls. The metal of the shaft conducts that heat to the senor.

Compare that to sticking the same metal thermo into boiling water, the shaft and probe are in the same temperature environment and the measurements are more accurate. But we have our thermos touching a column wall of one temp and vapor bath of another.
I think that is why I see a lot of people saying that their thermo is a bit off. The answer is to understand why it is off. Since the thermo is only guide, just apply a basic offset and you are good to go.

Lester I see you are doing that, I am just offering a possible reason for your irregular readings.

You'll note my readings are higher (hotter) than expected. That hotter temperature can not be the result of the heat losses from the column walls. Heat loss will always result in a lower (cooler) reading so I don't think the effect is due to heat conduction from the column walls.

[Lester]

I finally found some SS pot scrubbers. Soaked them in diluted hydrochloric acid for several minutes, rinsed, soak in water+baking soda, rinsed, boiled in vinegar, rinsed, and in it went into the column for some water cleaning run, then alcohol cleaning run.

I saw that The teflon tape wrap on the slide valve works very well, no more leaks from the VM port!!!

I have also found the sweet spot setting for my slide valve, about halfway into the 2" column. More than that and the temp slowly goes up. At this setting I only get fast drips now no more pencil-lead thick stream but that's alright with me.

It takes 55 minutes to heat up 18 liters of Birdwatcher's then another 3 hours to get about 1.4 liters of 87% ABV alcohol. I don't really understand why I can not reach 95% ABV even with SS scrubbers as packing. I put in 24 pieces of the 2" diameter scrubbies into 48" of packed column height.

I'm still searching for an alcometer cuz they sell it for US$44 over here....... which seems like way too much money to pay for a small piece glass.

[epplimp]

i just bought an alcometer today for $9.00 CDN. i found it at a beer and wine making store. it was the 12th store i went to though. the guy said he doesnt sell many of them. infact the only one hes ever sold was to a guy who thought his kid was stealing his booze. as it turns out the kid was and got busted. pretty funny. however your laws maybe different in the states. you can order them online from several brewing supply sights in canada from 6-11 bucks. good luck.