How can I fix this reflux rig? Expected 94% got 87%.

jbrew9999 · Post by **jbrew9999** » Tue Dec 06, 2005 11:19 am

My new reflux still didn't perform as I had hoped and I would like to know what can be done to tune it up.
Here are the specs from bottom to top:

Boiler: 8Gal ss pot with lid set on and sealed with flour dough.

Heat: 1500W water heater element inside pot.

Minimum water level to cover element: 5.5L

Column: height: 1.5m (60") Diameter: 2" ID (50mm) Insulated with foam pipe insulation

Column Packing: real copper mesh rolled into plugs, wrapped with a ring of copper wire to keep them from unrolling then stuffed into column. 11 5" long plugs for 55" total packing height.

Head: Bokakob based EL (eliptical disk) head with take off valve.

condenser: 16ft of 1/4OD copper in double helix coil stuffed with copper mesh resting in top of head fed by hose water.

The whole thing looks identical to "One Fiesty Old Lady"s new setup shown here -> http://www.photochicken.com/ims/pic/48VLcT7/4468.jpg" onclick="window.open(this.href);return false;" rel="nofollow

From those specs, and the theory and design sections of homedistiller.org, I was expecting to get 95% purity if I ran it slow enough. I didn't want to have to use carbon filtering to clean up the spirits.

The best I got out, at any rate was 87%.

The wash was a sugar wash with 10-12% Aclohol. After 95 minutes to reach boil, I fired up the condenser and let it sit in full reflux for 30 minutes. The temp at the top of the packing stayed at 80C the whole time. I broke my hydrometer just before my first reading so I had to rely on the temp to maintain the quality. I collected 60ml in a double shot glass and then 150 ml in jar 1 and set those asside. Then I started collecting the main body of the run I collected 1.5L slowly adjusting the flowrate to keep the vapor temp at 80C (the same temp as 30 minutes of full reflux) After that, the flow had been turned down to pretty slow so I bumped it up a little and let the temp rise to 88C for another 1.25L before opening the valve a little more and running the last 400ml out at between 88 and 94C. I was never collecting faster than 40min per Liter and usually slower than that. (note that I was closely watching the vapor temp just above the packing) the whole run took about 6 hours total-- 1.5 to heat up and set up, 3.5 - 4 to collect and 1 - 1.5 to clean up.

Everything was clear except the last jar that came out at up to 94C. That one was a little cloudy. There were distinct differences in smell between the first (shot glass), second (150 ml jar), the 3 at 80C, the 3 at 88C, and the last at upto 94C. I played with samples of each in my hands, on a spoon, with fire, diluted with water, and by smell and color and was pretty proud of my self.
It wasn't until a week later when I got a replacement hydrometer that I found out it didn't go as well as I hoped. I measured all the fractions, and adjusted for temperature and then compared to the readings from 2 different store-bought drinks (my hydrometer was reading 4% lower than actual). Then I diluted down one of the 80C pints into a liter of 40% vodka and tested it. It does taste like vodka and doesn't have a cardboard smell but it is much sharper than the other vodka I have. Next, I made up a pint of Liquor quik amaretto and found it to be rougher than I would have liked.

I'm not satisfied with my results. I want to be able to make smooth neutral spirits and my still design *should* be able to do it. What do you guys think?

I know the condenser is working fine, everything that should be sealed is sealed correctly, the valves work, and I can hear reflux overflowing in the head.

My analysis makes me think that my problem(s) HAVE to be with the column and not my process or takeoff rate since I drew off most of the spirit at the lowest temp I could achieve even in full reflux. Looking at the charts on homedistiller I am only getting 2 theoretical plates when my design should have closer to 10.

My reflux return overflow doesn't have a built in drip spout-- it doesnt drip the reflux into the center of the packing (I screwed that up when I installed it) Instead I fit a wire hanging off the center of the lower disk and suspended in the center of the head. I ran water through this and it seemed to work fine-- the water that flowed through the head (as if it was reflux) ran right down my wire and dripped out in the center of the column. That shouldn't have been my problem unless the wire moved out of its place.

My column also doesn't sit perfectly plumb, I had it shimmed to be pretty close to plumb though. Do you think this could be a problem that wastes 8 theoretical plates?

A couple times during the run, I bumped the column and it rocked back and forth quite a bit (becasue of the shims I mentioned above) and everytime I played with the valve, it would rock a little.

So far that is all I have got-- a possible problem with the reflux not flowing evenly down the packing. Can anyone think of anything else? Any other comments on my setup or process?

The Chemist · Post by **The Chemist** » Tue Dec 06, 2005 11:58 am

Hey, jbrew:
Slow down. I know you think you WERE going slow, but 25 ml/min is too fast for the purity you're after. Give the column a complete hour at equilibrium, then pull off no more than about 10 ml/min (~1.5 h/L). Clean up the next day if you have to!

jbrew9999 · Post by **jbrew9999** » Tue Dec 06, 2005 12:17 pm

Fair enough. But I couldn't get the vapor temp below 80C even at full reflux. Are you thinking that an extra 30 minutes in full reflux would have dropped it down to 78?

Uncle Remus · Post by **Uncle Remus** » Tue Dec 06, 2005 12:27 pm

You'll get higher av% if you collect slower for sure. With my reflux still I find the most efficient way is to do 2 runs.
The first run I reflux at about 4:1 reflux valve opened 1 turn and collection valve opened about 1/4 turn. Set like this I am collecting 100ml in about 4 minutes and during the middle of the run it is a constant 88% (using a wash 14-16%).
I run a couple washes in this manner, save up the product and then after I run it through again. Then the 93-94% comes easy.

linw · Post by **linw** » Tue Dec 06, 2005 12:54 pm

Your problem is very simple. Like the others say, your take-off rate is far too high but they didn't tell you why. You MUST get the power down. You just can't get great purity and high abv in a 2" column running with 1500W. Halve it and you will achieve your goals easily. Your temp of 80C tells the story. Given that the thermometer is accurate, you just haven't got pure etoh in that vapour.

A single element with no power control will work in a pot still but your excellent reflux column needs a power control mechanism. A cheap and efficient method could be to add another similar wattage element. By running them in parallel you get fast boil time and by running them in series you get quarter power (3000ish in parallel and 750ish in series). Alternatively, you need a large variac or electronic burst fire controller to drop the single element's power.

If you do this, you will easily get 95%+ but it will take longer to run. Those darned tradeoffs!

Good luck.

jbrew9999 · Post by **jbrew9999** » Tue Dec 06, 2005 1:15 pm

Thanks, Linw. But that doesn't match up with the calculations and empirical data from the "reflux still design theory--column diameter" section of homedistiller.org.

I used a 2" diameter column and found that at 750W the temperature gradient settled out 2/3 of the way up the column, at around 80cm. This told me that vapor moving at 28 cm/sec had fully separated after spending 2.5 seconds in the packing. Increasing the heat input raised the point at which the straight line met the curve, but when the curve reached the top of the packing, the curve switched to the straight line sharply, not asymptotically, and the temp in the top rose to match the increasing temp at the top of the packing. So using 1350W with a 25mm column would result in full separation occurring at a point right at the top of the column, with little or no leeway.

I'm using a 50mm column so I should be able to achieve full separation with more than 1350W of power. Especially in a 1.5m column.

Generally, a 2" (50mm) diameter is an ideal size to use. This will happily run from 750W up to 2500W without any trouble. If in doubt, go for 2".

How do I get Mike's results?

linw · Post by **linw** » Tue Dec 06, 2005 2:07 pm

Perhaps Mike's quotes are being misinterpreted. You don't want the separation point too high up the column as this gives "no leeway". You need a reservoir from which you tap the 95% stuff without collapsing the equilibrium. When you see the range of power levels that different diam pipes can handle, the top power bears little relation to the optimum power for highest purity.abv product. The top power probably relates to the power that can be handled before choking occurs. This also depends on the packing used.

Point 1. You have proved that 1500W of power doesn't allow proper separation. I have used a similar power but just for stripping.

Point 2. I, and MANY others, have proved that you can get great results at less power and longer runs.

Point 3. If there was a way of producing 95% from a 2" pipe at the take-off rate you were using, we would all be doing it. After all, I would love to be able to cut my run time from 11.5 hrs to 5 hrs. If someone can show how to do this, I will be the first to follow!

So, to get back to your original question, I have given you one method of achieving your desired result. If there was another better method that I knew of, I would have shared this with you. We await that better method.

jbrew9999 · Post by **jbrew9999** » Tue Dec 06, 2005 2:59 pm

Lindsay,
I really appreciate your replies and I'm not trying to try your patience at all. Thank you for your input.

linw wrote: Point 1. You have proved that 1500W of power doesn't allow proper separation. I have used a similar power but just for stripping.

I've only proved that my setup can't achieve proper separation at 1500W, not all 2" setups.

Point 2. I, and MANY others, have proved that you can get great results at less power and longer runs.

Fair enough. I was hoping that I could use the data collected by Tony to improve on those results.

Point 3. If there was a way of producing 95% from a 2" pipe at the take-off rate you were using, we would all be doing it. After all, I would love to be able to cut my run time from 11.5 hrs to 5 hrs. If someone can show how to do this, I will be the first to follow!

I agree. I wouldn't expect to be able to collect as fast as I did at 95% but since my rate didn't affect my vapor temp at all, it would have been a waste to collect any slower. If I could get my column to equilibrate at 78C, I would take off at what ever rate kept it there.

So, to get back to your original question, I have given you one method of achieving your desired result. If there was another better method that I knew of, I would have shared this with you. We await that better method.

Thanks.
I wonder how "mike" who Tony Ackland is quoting got his column to work that well. He got total separation with 1350W in a 1.5" x 119cm column. I would think that I should be able to achieve it with 1500W in my 2" x 140cm column. (I know this doesn't allow for any collection) Why would it be impossible for my column to equilibrate at 78C in full reflux?

Post by **Grayson_Stewart** » Tue Dec 06, 2005 3:05 pm

Column Packing: real copper mesh rolled into plugs, wrapped with a ring of copper wire to keep them from unrolling then stuffed into column. 11 5" long plugs for 55" total packing height.

What length did you cut each piece of copper mesh to roll into the seperate "socks" for lack of a better word? If you need a wire wrapped around them to prevent them from unrolling you may not have enough copper mesh in the column.

I use 1800 W with a 2" insulated column and I get low 90's no problem. If I want to slow down to 3 or 4 drops per second I can get the max. I think you have a problem with reflux short circuiting the mesh or not enough mesh period. I cut 48" long pieces of mesh off of my large roll...these were rolled up into a 2" diameter- 5" long "sock". And my column is only packed for 42" or 48" of height at that.

jbrew9999 · Post by **jbrew9999** » Tue Dec 06, 2005 3:28 pm

Grayson_Stewart wrote:
Column Packing: real copper mesh rolled into plugs, wrapped with a ring of copper wire to keep them from unrolling then stuffed into column. 11 5" long plugs for 55" total packing height.
What length did you cut each piece of copper mesh to roll into the seperate "socks" for lack of a better word? If you need a wire wrapped around them to prevent them from unrolling you may not have enough copper mesh in the column.

I use 1800 W with a 2" insulated column and I get low 90's no problem. If I want to slow down to 3 or 4 drops per second I can get the max. I think you have a problem with reflux short circuiting the mesh or not enough mesh period. I cut 48" long pieces of mesh off of my large roll...these were rolled up into a 2" diameter- 5" long "sock". And my column is only packed for 42" or 48" of height at that.

Thank you Grayson

That is just what I was hoping to hear. I cut the mesh into 65" lengths to make the 2" rolls. The wire rings are to keep them rolled up when they aren't in the column. I could take them off as I stuff the column. Does your column get any vibration during operation? Is it perfectly plumb?

Post by **Grayson_Stewart** » Tue Dec 06, 2005 3:38 pm

65" sounds like plenty of copper mesh...guess it depends on the type mesh you have though. Nope I've never had a vibration or noise from mine before. And I don't worry about how plumb it is....I have an offset head with a reflux return line that runs into the column and "tipped" to prevent surface tension from drawing the liquid back along the reflux line and down the column wall.

I hope you did notice that I said I run alot slower than you have been running yours...like the others said run it slower and you will get that purity up there. If running slower doesn't work let me know.

jbrew9999 · Post by **jbrew9999** » Tue Dec 06, 2005 3:53 pm

Grayson_Stewart wrote:65" sounds like plenty of copper mesh...guess it depends on the type mesh you have though. Nope I've never had a vibration or noise from mine before. And I don't worry about how plumb it is....I have an offset head with a reflux return line that runs into the column and "tipped" to prevent surface tension from drawing the liquid back along the reflux line and down the column wall.

I hope you did notice that I said I run alot slower than you have been running yours...like the others said run it slower and you will get that purity up there. If running slower doesn't work let me know.

Thanks. I have the exact same mesh as you. (You told me where to buy it.) I didn't mean vibration from the column-- I was vibrating my column quite a bit when I would adjust the flow rate, and at least twice, I bumped it and the rocked quite a bit. Do you ever bump or shake your column? Does it hurt the quality? Mine is wobbly because of the half-ass shims I used to plumb it. I was worried that it was so out of plumb that the reflux would quickly end up on the side of the column running down the inside of the pipe.

The most important thing you've given me is an example that works like I expected it to. You've been a great help. Before I run it again, I'll make sure it is more stable and my reflux is really dripping into the center of the packing.

I know I will have to run it slower once I get it to equilibrate at 78C, but I can run it as fast as the thermometer will let me, right? i.e. As long as I keep the thermometer at 78C, the quality will be consistant eventhough the collection rate will be much higher at the beginning than at the end?

How long do you let your column sit in full reflux before you start collecting?

Guest · Post by **Guest** » Tue Dec 06, 2005 4:34 pm

from what i have read...an hour (at least) is how long it should run at full reflux, then collect SLOW, real slow. don't try to hurry it along. 500ml an hour at least.

Post by **Grayson_Stewart** » Tue Dec 06, 2005 5:21 pm

I shim my keg up as well. The concrete pad the keg sits on isn't perfectly level and the column is ever so slightly off plumb when attached to the column due to heat distortion when the female coupling was soldered to the column. If you leave part of the boiler on the floor and shim two other spots it shouldn't rock....a three legged stool is pretty stable.

I don't think a couple of instances of rocking is going to do much to upset the equilibrium of your column.

I know I will have to run it slower once I get it to equilibrate at 78C, but I can run it as fast as the thermometer will let me, right?

Technically, yes. If you sit and watch the thermometer and the moment the vapor temp rises, increase the reflux return...but thats alot of trouble. It's really better to do as said earlier by others and let the upper portion of the column reach equilibrium.

How long do you let your column sit in full reflux before you start collecting?

I've done everything from 15 minutes to a little over an an hour in letting the column reach equilibrium. I don't see any difference in any amount of time over 30 minutes myself.

jim81147 · Post by **jim81147** » Wed Dec 07, 2005 6:55 am

Point 3. If there was a way of producing 95% from a 2" pipe at the take-off rate you were using, we would all be doing it. After all, I would love to be able to cut my run time from 11.5 hrs to 5 hrs. If someone can show how to do this, I will be the first to follow!

I agree. I wouldn't expect to be able to collect as fast as I did at 95% but since my rate didn't affect my vapor temp at all, it would have been a waste to collect any slower. If I could get my column to equilibrate at 78C, I would take off at what ever rate kept it there.

Wouldnt the fact that the temp stayed steady mean that by varying the take off rate you would be , infact , increasing or decreasing the reflux ratio ? That would then account for for the lower ABV correct?

jbrew9999 · Post by **jbrew9999** » Wed Dec 07, 2005 7:31 am

jim81147 wrote:
Wouldnt the fact that the temp stayed steady mean that by varying the take off rate you would be , infact , increasing or decreasing the reflux ratio ? That would then account for for the lower ABV correct?

Not quite. Vapor temp and %etoh are directly related, reflux is the means by which I manipulate the vapor temp. If the temperature of the vapor hasn't changed, the composition of the vapor also hasn't changed. However, you could be partly right since my termometer reads in 1 degree increments, there is some slack that could allow for slightly different compositions of spirit at the same measured temp. But that doesn't explain why I couldn't get my vapor temp below 80C (87%) even when under full reflux.

Additionally, I know that my thermometer is reading the vapor temp acurately enough (i.e. in the right place in the column) because my vapor temps and alcohol % match up with those from the charts on homedistiller.

Thanks for your input though. Other insight is still appreciated though I'm sure (thanks to Grayson) that what I am shooting for is posssible and I am being hindered firstly by how the reflux liquid is flowing down the column. I'm working on that problem.

Post by **Grayson_Stewart** » Wed Dec 07, 2005 8:03 am

If I had never produced what I have I'd be the one driving Linw's bandwagon based simply on theory...you would need to slow down and lessen the heat input, but I've got more heat than you and I have been able to wring the maximum out of mine.

At first I wanted to know what you got when you slowed down but you say under total reflux you don't see a temperature drop below 80 C. That just ain't good no way about it. I can get pretty much what your doing with a fully packed column and all reflux turned off.

I'd like to see a picture of the temperature probe placement on your column. You have checked the thermometer in steam and chilled water right? We may have already covered all that I don't remember.

jbrew9999 · Post by **jbrew9999** » Wed Dec 07, 2005 8:45 am

The thermometer probe sticks into a piece of 1/4OD copper that is soldered into the column. The probe tip was approximately centered in the column about 1" above the packing and the gap was sealed with bread dough. I don't have a picture.

I checked it in a glass of ice water (50/50). It was 1C in a few seconds and 0C after a minute. I didn't check in steam since I don't know exacty what the boiling point should be at my elevation nor what water contaminants may be affecting it. My vapor temps from my themometer and my %etoh readings from my hydrometer correlate pretty well to the graph of vapor temp vs. %ABV. Since I calibrated my hydrometer with 70% and 40% liqour and adjusted for temp, I deduced that the themometer reading must be accurate (though only precise to +/- .5 C).

For what its worth, I was getting less than 1500W effectively since it took 95 minutes for the wash to boil. That is about 15 longer than predicted and equivalent to about 1250W. The top of the boiler and most of the column are insulated and remained cold to the touch but there is lots of heat loss through the sides of the boiler.

linw · Post by **linw** » Wed Dec 07, 2005 12:26 pm

My assumption is that you want 95% etoh with high purity. There are heaps of threads on how to achieve this. I would suggest trying this one for starters.

http://tinyurl.com/9pngc" onclick="window.open(this.href);return false;" rel="nofollow

Look particularly for contributions from Harry, Mike Nixon and Mike McCaw.

jbrew9999 · Post by **jbrew9999** » Wed Dec 07, 2005 1:44 pm

linw wrote:My assumption is that you want 95% etoh with high purity. There are heaps of threads on how to achieve this. I would suggest trying this one for starters.

http://tinyurl.com/9pngc" onclick="window.open(this.href);return false;" rel="nofollow

Look particularly for contributions from Harry, Mike Nixon and Mike McCaw.

I have read tons of material on it. But not that particular thread. Thanks.

My personal goal is to get the cleanest etoh I can by using a rig optimized for efficiency. I see myself having lots of time in 5 hour blocks but very little in longer blocks like your 11.5 hours (I just have too many hobbies, odd jobs, and full time employment.) From my readings, I believe my rig should be able to get me 92-93% without breaking my time budget. Then on days when I have more time, I could slow it even more and shoot for perfection.

Both Tony Ackland and Bokakob have claimed good results collecting at rates around .75-1 L/hr.

(from Tony)It will then sit there for the next 2.5-3 hours, and I collect the distillate at the rate of approx 1L/hour. (with my improved reflux still, it now sits steady on 78.2-78.4C for most of this period - eg 95% purity) Slowly towards the end of this period, the temperature slowly starts increasing up towards 90-94 ° C. By this stage, my hydrometer shows me that the alcohol is only about 40%, and I've usually had enough, so I then turn it off. Total time 4 hours. (with the new reflux still, I finish collecting at around 82C, as past there it deteriorates fast towards the rubbish - still 4 hours though)

For now, I'm going to try and fix my reflux drip spout and better plumb and stabilize my column. Hopefully, that will allow me to meet my quality and time goals.

jbrew9999 · Post by **jbrew9999** » Thu Dec 08, 2005 4:57 pm

theholymackerel wrote:
jbrew9999 wrote: For now, I'm going to try and fix my reflux drip spout and better plumb and stabilize my column. Hopefully, that will allow me to meet my quality and time goals.
Why not just do a strippin' run first?

A strippin' run can be done quickly, and later, when you have time, you can do the second run. The second run startin' with a higher ABV% wash will be able to be run faster while still gettin' good purity.

Thats still a valid option. My only problem with it is I've got to leave 5.5L minimum in my pot to cover the element, so to make it possible, I'd probably have to dilute it a lot to redistill, or combine 3-4 runs. That may turn out to be the best choice in the future but for now that's a lot more into this hobby than I wanted to be before I got any good results to show to the wife.

Guest · Post by **Guest** » Thu Dec 08, 2005 6:04 pm

I think the strippin run is a great option too. That is the way I usually do it myself(depending on what it is that I am running). I run 3-4 5 gallon batches fast and dirty, then combine them for one nice run.

~Pothead

junkyard dawg · Post by **junkyard dawg** » Fri Dec 09, 2005 1:04 am

I have to agree on the stripping run... I've recently branched out alot in this hobby and stripping runs and reflux columns have been a major part of it. from my experience, stripping and saving 3 or 4 runs not only saves time in the long run, but also goes a long way in cleaning up your neutral spirits.

jbrew9999 · Post by **jbrew9999** » Mon Jan 23, 2006 8:16 am

Success.

The primary problem was a channelling effect that was bypassing most of the packing. I ended up just grabbing the lower plate with a pair of pliers and tearing a notch in it to direct the reflux down the center of the column instead of along the column wall.

Before, the column couldn't get below 80C. This time, once boiling started, the thermometer shot up to 80C and then dropped over 20 minutes to 76C as the column equilibriated. It held there for 15 more minutes (35 min total in full reflux) I was too busy to tinker with the flow rate so I got it set at 90min / L and left it until the tails. Nearly everything came off at 76C.

The difference in separation was amazing. Before, there was little difference between what came off at 82C and what came off at 88C. Now, what came off at 77C was foul next to what came off at 76C.

I'm estimating that the etoh content is 95%. My Hydrometer isn't accurate. It measured known 40% vodka and 40% Gin at 36% and known 70% rum at 67% at the calibrated temperature. My output measured 93% side by side with these at the same temperature so it must be at least 95%.

Thank you all for the helpful comments.

linw · Post by **linw** » Mon Jan 23, 2006 6:40 pm

Yep, that would do it! Congrats on becoming the owner of an excellent reflux still.

As you have now found, ANY move upwards in temp is telling you it is scrambling the purity. Even 0.1 of a degree needs attending to!

Onwards and upwards from here.