First run of VM mod to Boka seems slow

[mr_stiller]

As built

I purchased a 2" X 32" boka style reflux still with copper scrubber packing, insulated.
It has a 8" double worm condenser at the top and a 10" Leibig on the Lyne arm.
Boiler is a 6 gal beer keg with electric heat, controlled with a heavy duty router speed controller.
I built a 1" VM arm that has a 8" double worm condenser. I added an extension to the column that moved the reflux condenser up 4".
The VM takeoff is above the plates in the column.
On my first run the vapor valve (316SS, 1 1/4 ") is full open, and I am getting about 1 drop per second out of the VM arm.
I measured 300 ml of product in 2 hours.
This seems awfully slow. Temperatures are normal, started at 178F and now 184 F.
No vapor loss at the top vent.
Product is 87-88% ABV. Is this normal?

[vetting]

Is your takeoff tube still right on bottom angle plate? Its a little hard to tell from the phot

What is the size of your output tube? Remember, your output tub has to be right were the bottom of your bottom angle plate is. If its too high up it will just spill back over the edge of the angle plate. Also, if you really are using that large of a tube as shown in the picture and having it straight out like that, anything that isnt on a downward slope will result in nothing coming out. If thats the case, just tilt you still towards your output to see if that is the issue.

The point of a boka is to collect the already condensed vapor. The way you have it setup is more to catch the vapor, which it wont since your still would have to pressurise to make the output go out that arm.

You would be better off with a small sized output and put a water jacket around it to cool the liquid more if its coming out too hot.

[Coaster]

@ mr_stiller,

Suggest visiting the Research and Theory sub-forum and review the Some Still Drawings thread and note the placement of the thermometer in Vapour Management Stills. In Vapour Management Still the vapour temperature is measured in the Vapour Management take off port. In your particular Still configuration you are measuring the temperature well below your Vapour Management take off port. With measuring the temperature well below your Vapour Management take off port you are operating you Still at a low vapour temperature and not providing sufficient alcohol vapour to your Vapour Management take off port. Also most likely are not providing sufficient alcohol vapour to your reflux condenser to provide reflux to the Still Column.

Also in your particular Still configuration your slant plates are well below your reflux condenser. Suggest closely reviewing the ‘Some Still Drawings’ thread and note the conventional configuration of Slant Plate/VM Combination Still builds. There are known proven valid reasons why the Slant Plate/VM Combination Stills are designed and built in the manor depicted in the Some Still Drawings thread. Suggest taking advantage of the known proven information provided in the ‘Some Still Drawings’ thread.

Regards,
Coaster

[maheel]

something is up ?

try this
turn the still off
grab a small jug of water say 500ml
open the "boka valve"full and close the VM valve
tip the water down the top through the condenser in a steady stream about the size of a pencil

what happens at the boka output ?
it (the water) should pour out about as fast as it can depending on the size of the output

if it does not you might have a blockage or a design fault

apart from that what volts / watts is the heat input

[Ayay]

Column height is the height of the packing, and it appears to be less than 24" in the pics as far as I can tell. The packing does the purifying and all of the column above the packing is for condensing and controlling the reflux (which goes back into the packing).

You have three condensers!!! A pot still needs only one, a boka (LM) needs one, and a VM needs two. The third condenser on your setup is likely the one on the boka product outlet which is not a condenser but just there to cool the product from a warm liquid to a cool liquid...a luxury rather than a necessity.

Collecting at 1 drip/sec should produce 90%+ even with a 20" packed column provided the reflux is working properly.

Try removing all the reflux and running your rig as a pot still by doing either: In LM mode this means closing the VM valve and opening the LM valve full open, and only use the top coil condenser. Or in VM mode, close the LM valve, open the VM valve full open, close the vent on the top of the column, and only use the VM leibig condenser. By doing one of these your only control of the output is by controlling the heat input, and you will find out if the heat is really being controlled. Forget the thermometer for this test. Try to get one drip/sec by controlling the heat input. Turn up the heat until the condenser can barely cope and see how much product comes out. The min is how low the heat can go and the max is what the condenser can handle, all measured by the flow out of the product outlet regardless of vapor temp or ABV. Knowing these basics is knowing your still and then your experiments with the reflux will be meaningfull.

Pot stillers get good results by heat control alone.

[mr_stiller]

Wow, thanks for all the suggestions. I especially appreciate specific experiments that I can try.
I will report results later when I get a chance to try them.
I studied Samohons pix and drawings, and I now understand where I went wrong.
The VM output needs to be below the Boka output plates, not above. Is that right?

[Coaster]

To alleviate the “Confusion Factor” refer to the below referenced drawing ->



This drawing is available for close review at the below Forum link ->

http://homedistiller.org/forum/download ... &mode=view

Regards,
Coaster

[mr_stiller]

Beautiful, Coaster, thanks to all.