Boka troubleshooting

[durgan]

I just finished my Boka build. It is a 3 foot column with 8" long 1/4" tube condenser single wind and 1/2" cold finger. There is packing of copper scrubbers at the bottom of the column. Everything seems to work well but I tried a run with cheap wine diluted with some water after the cleaning run and noticed two things.

The temperature does not seem to increase past 140 degrees Fahrenheit. If my target is 78 C then that should be around 172 F. The thermometer is placed right underneath the top plate. Maybe this is because my column is longer than the boka in this design: http://homedistiller.org/wiki/index.php/images/Mini_explained.jpg" onclick="window.open(this.href);return false;" rel="nofollow

Also I noticed some water or wash surging/spitting out of the top of the column every once in a while when the condenser is running. It's not much but does not seem normal. The condenser does seem to be knocking down all vapor normally except for this occurrence.

Any help is greatly appreciated.

Also hot wine smells pretty bad.

[rad14701]

Sounds like a choking and flooding issue to me... You should NEVER end up with liquid wash or spirits coming out the top of the column... You are pushing too much heat or have the column packed too densely - or both... Column height is not the issue as all as it merely helps assure purity when the column is driven properly...

There are several informative topics which cover Bokakob, and LM stills in general, that you should find helpful...

[Usge]

Along with Rads advice, you might also check your condenser for a leak. This could explain both the spray out the top you saw...as well as the low temp that would not rise.

[durgan]

Thanks rad and usge. I will try turning the heat down and insulating the column. Also I will double check the condenser for a leak but I did not see one unless it leaks while working during use.

Thanks for the advice. I appreciate it.

[Usge]

durgan, pull the condenser out of the column and run water through it. Hold it up in your hand. If it's leaking, you'll know it right away.

[durgan]

Hey Usge,

I have been experimenting and I tried loosening the packing plus insulating the column. I am still seeing similar results and getting a little discouraged at this point. I tested the condenser for leaks and do not see any at all but I can understand why this would cause those symptoms. I was wondering if my plate placement or the notch in the bottom plate might be causing the overflow? I did use the 1.5 inch diameter template and they seem to be accurate in alignment.

I am not sure what else to try but will do another run tomorrow and see what happens. Is it possible I might just need to turn the heat down and let it stabilize for maybe an hour to hit temp?


Thanks again

[rad14701]

What is the air gap between plates...??? The original templates had a small air gap which can potentially cause choking and flooding... Newer templates have a gap of 3/4" for 1.5" and 2" columns and 1" for 3" columns, as I recall... Small air gaps between plates causes a more drastic vapor speed increase which can impede reflux from returning back down into the columns structured packing... The only way to negate this possibility is to fine tune heat input to reduce interference at the choke point created by the slant plates...

[durgan]

The gap between plates is 1/2 inch or greater. Thanks for the info. I will experiment more tomorrow and fine tune the temp. I might be able to retrofit the top plate if it turns out they are too close together.

Cheers all. I appreciate the help.

[Usge]

durgan, lets move on to another test here. Perhaps it's just the temp "reading" thats off? Does it seem to function/perform just fine otherwise?? (ie., what is the proof of your distillate)?

In that particular regard...a few things to check. If your temp probe is touching the bottom of the bottom plate...it can throw it way off. If the temp probe has liquid (refluxed distillate and/or condensed water dropplets), dripping onto the probe, it's going to be off.

Because the bottom plate angles "down", if you push the probe in too far..it could (depending upon how far away vertically it is from bottom plate) either make contact with the far edge of the plate and/or have distillate dripping on it. Either way, will keep it from registering temp properly. So, this is something to check. I started with a K-type probe just pushed into smaller tube fitted with PFTE tape. I found if I even wiggled it a little, the temp would vary quite a bit. So, I opted for a more solid mount. Some people use compression fitting drilled out, etc. I prefer threaded fittings. You can buy a dial therm with 1/4 NPT for about 30 bucks. They don't give the fine (decimal) feed back a digi one will. But, they are solid and reliable. I found a K- type 1/4 NPT threaded probe for my digital therm. It's not quite as sensitive as the other probe, but it's more reliable.

[durgan]

Hey,

I tried a run this morning and it seemed to run great. Between the propane and water adjustments it was finicky but I got it dialed in and it was running perfect. I got through foreshots and started collecting heads when a perfectly nice day decided to throw me gusts of wind that threw off the flame and temps were all over the place. I shut it down for the day. I will look into that dial therm with threads.

Can I restart from where I left off tomorrow?

Also, Is there a way to use a sump pump and circulate cold water from a vessel instead of wasting water? I tried this sump pump method but could not keep the water cool enough when it returned to the condenser. The pump is 1268 gallons per hour. I thought about running a coil of copper or plastic through the fridge from the pump and have it return to the "in" side of the condenser.

I was a little discouraged for a while here to be honest but it's working now thanks to you guys.

[rad14701]

You'll want to go through the motions of checking for foreshots and heads when you restart tomorrow...

As for recirculating the water, many members go that route... Even if the water in your reservoir starts to warm up you won't need to replace as much as wasting all of the water passing through the cooling circuit...

[durgan]

Thanks rad. It is still a bit windy today so I can hopefully try again tomorrow.