Crossflow build for my Bok

Anything cooling/condenser related.

Moderator: Site Moderator

Post Reply
User avatar
Expat
Site Donor
Site Donor
Posts: 1929
Joined: Fri Feb 24, 2012 3:58 pm

Crossflow build for my Bok

Post by Expat » Wed Mar 26, 2014 7:04 pm

After much reading and thinking I got around to building the crossflow condenser. Definitely the most complex build i've undertaken to date, so I thought I would share the results and some of the details.

Previously I was using a double wound coil, which was functional but essentially used up every inch of head room available in my work space. My intent is to maximize the amount of height available for packing; also its hard to resist a fun build project :lol:

So here is the completed build:
finished.jpg
interior downview.jpg
The shell of the condenser is 2", and the total width is 18"; internal setup is 21 flow tubes of 1/4" that are 16" long. To be clear, its designed to be overkill :twisted: I'd rather have more than I need.
interior tubes.jpg
Reading through the forums, one of the biggest build issues noted was the blind weld of the end caps over the tube plate; with this in mind I thought it would make sense to go with a removable cap joined by an EasyFlange. As a side benefit this means that the water path is open an inspection/repair if required.
Complete pre assemble.jpg
Left-cap.jpg
assemble right.jpg
To be continued...
_____________________
EXPAT

Current boiler and pot head viewtopic.php?f=50&t=71855
Cross flow condenser viewtopic.php?f=87&t=47632
Modular 3" Boka - pics tbd
___________________

User avatar
Expat
Site Donor
Site Donor
Posts: 1929
Joined: Fri Feb 24, 2012 3:58 pm

Re: Crossflow build for my Bok

Post by Expat » Wed Mar 26, 2014 7:09 pm

Some pics of the build components:
pre assemble 3.jpg
pre assemble.jpg
Plate and tube assembly in progress
Plate and tube assembly in progress
Not shown in any of the pics is the vent, since it was added afterwards :) I deliberately added a slight slant to the arms of the condenser to ensure that there would be no pooling.

I did a pressure test on the vapour side and there was no leaking whatsoever; Next step will be a cleaning run, and with that its ready to use!

Its not the most artistic build but i've had a lot of fun doing it. :thumbup:
_____________________
EXPAT

Current boiler and pot head viewtopic.php?f=50&t=71855
Cross flow condenser viewtopic.php?f=87&t=47632
Modular 3" Boka - pics tbd
___________________

Tap
Swill Maker
Posts: 250
Joined: Thu Sep 05, 2013 4:13 pm

Re: Crossflow build for my Bok

Post by Tap » Wed Mar 26, 2014 8:13 pm

Love it, very well thought out. :thumbup:

Did you use soft and hard solder? I couldn't imagine soldering 21x1/4" within a 2 incher.
Too much of anything is bad, but too much good whiskey is barely enough

User avatar
Expat
Site Donor
Site Donor
Posts: 1929
Joined: Fri Feb 24, 2012 3:58 pm

Re: Crossflow build for my Bok

Post by Expat » Wed Mar 26, 2014 10:40 pm

Thanks Tap :)

Truthfully, I'm not 100% what the difference between those would be; everything was done with a silver solder if that helps.
_____________________
EXPAT

Current boiler and pot head viewtopic.php?f=50&t=71855
Cross flow condenser viewtopic.php?f=87&t=47632
Modular 3" Boka - pics tbd
___________________

Soggy Bottom Boy
Rumrunner
Posts: 746
Joined: Sun Sep 09, 2012 4:43 pm
Location: Somewhere to the north of the.. ..Peoples Яepublik of Kalifoяnia

Re: Crossflow build for my Bok

Post by Soggy Bottom Boy » Thu Mar 27, 2014 12:03 am

.

On my first read-through of your post, I missed the part where you said that you added vents later, skimmed right over it. I even made a post that asked where in the H-E-double-hockey-sticks are the vents to atmosphere. (deleted it after I re-read the post again)

You should post up a pic of the vents, too. Just so some n0Ob doesn't build himself an explode-o-still by just looking at the pics.
"Well, ......I don't want Fop, goddamn it! I'm a Dapper Dan man!" ...Ulysses Everett McGill

"Good thing you found HD. It's like the mythbusters of distilling." ...Prairiepiss

MBF
Site Donor
Site Donor
Posts: 28
Joined: Tue Nov 18, 2014 12:15 pm

Re: Crossflow build for my Bok

Post by MBF » Sat Nov 22, 2014 2:58 pm

Man, I love the evolutionary inventiveness of the folks here. I'm planning to use a cross-flow reflux condenser for my LM/VM setup, so I am reading through all the JCF designs I can find.

1) I love the idea of capping the ends with tri-clamp plates.... for repair/inspection access AND for cleaning.

2) I also am intrigued with the idea of pre-building the "v-slant" into the arms to encourage condensate flow.

Let me offer another evolutionary idea:

Core End Plates:

1) Increase the plate thickness to 1/4".
2) Mill a groove in the outer diameter of the plate (flat end-cutter will work, but you could also go the extra step and use a ball-end cutter)
2-1) Optional? round over the inner/outer edges of the plate perimeters. This will minimize potential plate dragging on insertion.
3) Select a PTFE o-ring of sufficient size to fit this groove

Now, with the proper depth of groove and proper o-ring sizing, you have a removable cooling core. :)

Additionally, making this a removable core will also negate the need to hard solder the cooling tubes into the end plate.
Last edited by MBF on Mon Nov 24, 2014 12:45 pm, edited 1 time in total.

MBF
Site Donor
Site Donor
Posts: 28
Joined: Tue Nov 18, 2014 12:15 pm

Re: Crossflow build for my Bok

Post by MBF » Sat Nov 22, 2014 3:39 pm

Came up with another REALLY good reason to use the tri-clamp end plates:

Theory dictates that your inlet should come in from the bottom and that your outlet should exit at the top (or use a standpipe or other solution to insure the warm water exits at the top to work with the thermodynamic properties and prevent voids). IF you can remove the end-plates, you can vary the orientation of the inlet/outlet angles.

THUS, your cross-flow condenser can have multiple orientations (horizontal Tee with a 0 degree, 45 degree or 90 degree offset, et al.) You simply clamp the end plates at the desired angle.

Now, this would also necessitate the re-orienting the angle/height of your vent tube. This can be accomplished by simply by putting a sweat-on to threaded fitting on the end of the tube. Then, if you aren't set at the typical 0-degree offset, you can add a 45 or 90 degree threaded fitting with a short piece of tubing in the other end and bent as required to get the vent above the top of the main tube (with a j-bend at the top of course).

Finally, we arrive at a true, modular, multi-orientation, cross-flow condenser that can be used in almost any column design.

sungazer
Bootlegger
Posts: 123
Joined: Sat Dec 05, 2015 11:45 pm

Re: Crossflow build for my Bok

Post by sungazer » Thu Dec 17, 2015 10:22 pm

Very nice and a great solution to maximize the still efficiency with the space you have available. I wanted to make a comment on the vent not sure which post to put it in?

I was thinking that the vent to the outside is not just needed for any Vapor to escape to prevent an explosion if the pressure went up. But also when thinking about it if you are taking liquid out of a confined space you have to replace that space with something or a vacuum would occur. We don't want a vacuum occurring we want the space once occupied by liquid to be replaced by air this has to get in somehow? Had the amount of air is going to be equal in volume to the volume of liquid we distill out.

so if you think about it If you are taking off spirits at 2L an hour 2L of Air per hour has to enter the barrel and that air is going to have to enter down the column and from a vent somewhere so don't shut them up too much.

Happy to be corrected if I am wrong about this.

User avatar
Expat
Site Donor
Site Donor
Posts: 1929
Joined: Fri Feb 24, 2012 3:58 pm

Re: Crossflow build for my Bok

Post by Expat » Fri Dec 18, 2015 8:06 pm

Sungazer - Thanks for the feedback on the build.

Re the atmospheric vent, its an important safety feature. When you heat any material, particularly fluids and gases, they expand. Unlike a pot still LM stills like a BOK have a valve on the take off which would, without a vent, create a sealed vessel. Vapour expanding within a sealed vessel creates pressure which can build up to destructive levels. This could occur if an output valve is in shut or condenser cooling is insufficient. There really hasn't got any bearing on the need for air to equalize the reduction in volume from distillate removed, plenty of air will be able to move through the out take to replace it.

An atmospheric vent ensures that any pressure is released before it becomes a problem. Its a critical build component and must be included.
_____________________
EXPAT

Current boiler and pot head viewtopic.php?f=50&t=71855
Cross flow condenser viewtopic.php?f=87&t=47632
Modular 3" Boka - pics tbd
___________________

sungazer
Bootlegger
Posts: 123
Joined: Sat Dec 05, 2015 11:45 pm

Re: Crossflow build for my Bok

Post by sungazer » Fri Dec 18, 2015 8:28 pm

I understand exactly what you are saying. But I have read a lot of posts about venting here and design considerations and no one seems to address the issue that the boiler needs to equalize for the reduction in volume from the distillate removed. From what I can see the only path that the air can take is through the vent that most people install or insure they have for the exact opposite function which is the over pressurization from the gasses expanding. I do not have a completely open top on the condenser column but I do have large enough gaps around the coil ends to allow venting either in or out. I think I could nearly measure the flow to some degree I can certainly feel a flow.

Sorry for putting this topic on your truly very nice Build post.

joeymac
Swill Maker
Posts: 306
Joined: Sat Oct 17, 2015 6:22 pm

Re: Crossflow build for my Bok

Post by joeymac » Mon Dec 21, 2015 8:28 am

I understand exactly what you are saying. But I have read a lot of posts about venting here and design considerations and no one seems to address the issue that the boiler needs to equalize for the reduction in volume from the distillate removed. From what I can see the only path that the air can take is through the vent that most people install or insure they have for the exact opposite function which is the over pressurization from the gasses expanding. I do not have a completely open top on the condenser column but I do have large enough gaps around the coil ends to allow venting either in or out. I think I could nearly measure the flow to some degree I can certainly feel a flow.

Sorry for putting this topic on your truly very nice Build post.
You don't need air to come into the boiler to make up for volume lost to distillate removal because newly boiled ethanol vapor will easily take up that volume. But yes, the vent does "breathe" in and out, but it's usually very minor depending on the steadiness of the equilibrium reached.

I actually don't run an open vent on my boka... I use a liquid airlock similar to what you see on a fermenter. I have a vent hole and a clear tube that extends from the vent away from the column and the end of the clear tube is submerged about 1-2 inches below the surface of a small container of water. This means that for my still to vent, it has to overcome a couple of inches of water pressure. Likewise, to suck in air, it has to pull water up the tube enough to expose the opening to air. So what I end up with a very visual and audible (bubbling/sucking) indicator of any over/under pressure condition. The whole foggy mirror/glass method works OK, but I like my method even more as it more easily gets your attention if something is out of equilibrium.

Anyways, the water level in my tube and airlock container is usually equal but it does flutter above and below level a few mm as the still tries to "breathe", especially while adjusting my cooling water or product takeoff rates.

I guess technically you do not need a vent tube at all... but this would extremely dangerous. In the event of a cooling coil failure or during column heatup and vapor rise within the column, the still could explode if the takeoff valve were closed. Likewise, if you lost heat input while your cooling coils were still running then a vacuum would be produced and your still could be "crushed" by the ambient pressure. See example of a boiling vessel sealed off and then cooled, haha: https://www.youtube.com/watch?v=uZ7WFhJvQOA" onclick="window.open(this.href);return false;" rel="nofollow
"Woe to those who are heroes at drinking wine and champions at mixing drinks" - God (Isaiah 5:22)
So evidently, God wants us to drink our whiskeys single barrel and our Bourbons neat.

sungazer
Bootlegger
Posts: 123
Joined: Sat Dec 05, 2015 11:45 pm

Re: Crossflow build for my Bok

Post by sungazer » Tue Dec 22, 2015 9:06 pm

I think you are underestimating the size or the amount of air that needs to get into the boiler to replace the distillate. In my case I normally aim for at least 10% ABV in the wash sometimes up to 18% ABV in a 40L wash that equates to 4-7L of of air that needs to come into the boiler to replace the distillate taken off. If this was not replaced there would be a huge vacuum in the boiler and the process just wouldn't work.

User avatar
skow69
Site Donor
Site Donor
Posts: 3230
Joined: Tue Dec 06, 2011 3:03 am
Location: Cascadia

Re: Crossflow build for my Bok

Post by skow69 » Tue Dec 22, 2015 10:24 pm

As the wash boils the volume of vapor produced is roughly 1600 times the volume of liquid consumed. That should handle the 4 - 7 l.
Distilling at 110f and 75 torr.
I'm not an absinthe snob, I'm The Absinthe Nazi. "NO ABSINTHE FOR YOU!"

joeymac
Swill Maker
Posts: 306
Joined: Sat Oct 17, 2015 6:22 pm

Archimedes has a Sad.

Post by joeymac » Wed Dec 23, 2015 8:06 am

sungazer wrote:I think you are underestimating the size or the amount of air that needs to get into the boiler to replace the distillate. In my case I normally aim for at least 10% ABV in the wash sometimes up to 18% ABV in a 40L wash that equates to 4-7L of of air that needs to come into the boiler to replace the distillate taken off. If this was not replaced there would be a huge vacuum in the boiler and the process just wouldn't work.
If you're removing ethanol from the system, it's because the column is full of ethanol due to boiling. If ethanol vapor is heavier than air, how do you propose the air displaces the ethanol and gets down to the boiler... and then what keeps the heavier ethanol vapor from just pushing the lighter back up and out the column?

There is some air in a reflux still but it sits within or above the coil. Everything below the coil is distillate vapor or reflux. Everything.
If air were to get in your still, it would be about the most dangerous thing ever. Vaporized ethanol + Air (oxygen) + Heat = Explosoin.
"Woe to those who are heroes at drinking wine and champions at mixing drinks" - God (Isaiah 5:22)
So evidently, God wants us to drink our whiskeys single barrel and our Bourbons neat.

sungazer
Bootlegger
Posts: 123
Joined: Sat Dec 05, 2015 11:45 pm

Re: Crossflow build for my Bok

Post by sungazer » Wed Dec 23, 2015 3:31 pm

I am happy to be proved wrong so I am not taking a back against the wall stance here. I am happy to accept that Vapous could be expanding and taking some of the room of the removed distillate however if what you are saying is true then there would be an almighty rush of air trying to get into the boiler when the gas is turned off. I have had to turn off the gass once before and throw a bucket of water onto the keg to remove as much heat from the system before tackling a small fire. There was no sudden implosion which I think is what would happen if there was not a return of air continuing to happen throughout the process.

As for the vapor being heavier than air this may be a fact but I am sure it doesn't exclude all air from being able to mix with it and return back down the column with the re-fluxing liquid.

joeymac
Swill Maker
Posts: 306
Joined: Sat Oct 17, 2015 6:22 pm

Re: Crossflow build for my Bok

Post by joeymac » Wed Dec 23, 2015 3:54 pm

As I mentioned a day or so ago, I run an airlock on my still instead of an open vent because I prefer the visible & audile indicator versus a plain mirror fogging. Otherwise, my still is airtight.

I primarily use an induction hotplate. If I pop a circuit breaker or the burner times out (60min "safety" shutoff feature if I forget to hit a button :x) the still sucks the water out of the airlock in about 5 seconds until the vent hose is exposed. It then proceeds to gurgle on the tube for another 10 seconds or so like a fat kid trying to suck the last bit of milkshake from his his straw. The first time that happened I almost did away with the whole airlock thing... but then I decided to just use 95% neutral spirit so that when it happens I only end up dumping good spirit onto the column.

So yeah, at least my still sucks in a ton of air when I turn it off.
"Woe to those who are heroes at drinking wine and champions at mixing drinks" - God (Isaiah 5:22)
So evidently, God wants us to drink our whiskeys single barrel and our Bourbons neat.

User avatar
skow69
Site Donor
Site Donor
Posts: 3230
Joined: Tue Dec 06, 2011 3:03 am
Location: Cascadia

Re: Crossflow build for my Bok

Post by skow69 » Wed Dec 23, 2015 4:48 pm

Sounds like time for sungazer to put an airlock on his still because, obviously, logical arguements are not going to sway him
Distilling at 110f and 75 torr.
I'm not an absinthe snob, I'm The Absinthe Nazi. "NO ABSINTHE FOR YOU!"

sungazer
Bootlegger
Posts: 123
Joined: Sat Dec 05, 2015 11:45 pm

Re: Crossflow build for my Bok

Post by sungazer » Wed Dec 23, 2015 5:28 pm

skow69 wrote:Sounds like time for sungazer to put an airlock on his still because, obviously, logical arguements are not going to sway him
Skow I don't know why you say that. I said in my post I was happy to be proved wrong and I am debating here and listening to people especially those that have some math or practical examples that show evidence one way or another. Not just reaping stuff that they have heard from someone else that has never been tested. In fact joeymacs last post shows that his boiler did in fact need to take a large breath of air when it was turned off. I think that clearly proves that I am not totally misguided. If joeymac's still didn't have the airlock on it it would have been harder to see but this defiantly shows it. What if the airlock wasn't there, it would be creating a pressure drop to some degree for reverse flow would the air have been able to get in more slowly?

User avatar
skow69
Site Donor
Site Donor
Posts: 3230
Joined: Tue Dec 06, 2011 3:03 am
Location: Cascadia

Re: Crossflow build for my Bok

Post by skow69 » Wed Dec 23, 2015 7:06 pm

OK, I was getting the impression that you were rejecting all arguments that disagreed with you, but maybe not.
if what you are saying is true then there would be an almighty rush of air trying to get into the boiler when the gas is turned off.
Consider this. You turn off the gas. A few seconds later you hear the boiling stop. You are monitoring column temperature. It takes what? maybe 60 seconds for the column to cool below boiling temp. In that 60 seconds all o the vapor in the column condensed, diminishing in volume by a factor of 1600. [Actually that is water, ethanol is less, but let's go with that.] It effectively vanished. and was replaced by air from outside, just like you say. A 2" X 48" column has a volume of 150 cu. in. or roughly 2500 ml. But some of that is occupied by liquid reflux and packing, say 50%? Then 1250 ml of air had to rush in over 60 seconds, or 20 ml/sec. Think half a shotglass per second. we breathe more than that. A 1/16 inch hole won't have any problem with it. And that was the big rush. Any more volume loss has to come from the charge contracting as it cools, which takes what? an hour or more?

So there is nothing going on there that is even detectable unless you have some clever method like joeymac. Certainly nothing that would collapse your still because the air couldn't get in fast enough because of restriction at the vent. If you don't believe my specs, please look them up. Check the timing on your own still. I could be off, but at 20 ml/sec I've got a wide margin of error.
Distilling at 110f and 75 torr.
I'm not an absinthe snob, I'm The Absinthe Nazi. "NO ABSINTHE FOR YOU!"

joeymac
Swill Maker
Posts: 306
Joined: Sat Oct 17, 2015 6:22 pm

Re: Crossflow build for my Bok

Post by joeymac » Wed Dec 23, 2015 9:50 pm

I wouldn't describe the air suction as dramatic by any means.
Now, if you actually had no pressure relief it might get interesting and twist up your boiler some.
I wonder if a standard keg can support vacuum distillation :egeek:
"Woe to those who are heroes at drinking wine and champions at mixing drinks" - God (Isaiah 5:22)
So evidently, God wants us to drink our whiskeys single barrel and our Bourbons neat.

sungazer
Bootlegger
Posts: 123
Joined: Sat Dec 05, 2015 11:45 pm

Re: Crossflow build for my Bok

Post by sungazer » Wed Dec 23, 2015 10:18 pm

I believe your math it sounds reasonable. I was never really thinking in terms of damaging a boiler or such, more just the thought that a vent was needed for air to pass both ways. The pressurization of the boiler is always talked about and for good reason the 1600 if that is the number is going to produce a significant result. Like you say the 4L of air to replace the distillate over 2-4 hours is not huge but just something I think should be considered in the complete system process.

A part of my job used to be working out the specifications or uncertainties for a particular measurement for this you have to look at each contributing factor so when I see a system I look for all the factors that are occurring this is one factor that doesn't seem to have be mentioned and quantified then the effect considered. So I just wanted to throw some light on it.

Personaly I like to think the air is being replaced in a steady flow. What effect does it have on the rising vapor if any? Perhaps as you say or as in joeymac's configuration this replacement all happens on the cooling down of the boiler.

Hound Dog
Master Distiller
Posts: 3002
Joined: Wed Jul 31, 2013 4:45 pm
Location: Hounds Hollow, VA

Re: Crossflow build for my Bok

Post by Hound Dog » Sat Dec 26, 2015 6:28 am

Way over thinking the process. When your old tea kettle sits on the stove and starts to boil, the steam is steadily whistling out of it, it's not sucking air in to replace the water. When you turn off the heat, you are done. Let it suck in all the air it needs then.

In the perfect world your condensing coil is returning it back to liquid so the cycle should be the same and it could be sealed BUT, anything goes wrong and it is a disaster.

Just vent the top.
LM Still Operating Instructions
Cranky's New Distiller's Advice
Using Google Search

Drinking Rum before noon makes you a Pirate not an alcoholic.

User avatar
skow69
Site Donor
Site Donor
Posts: 3230
Joined: Tue Dec 06, 2011 3:03 am
Location: Cascadia

Re: Crossflow build for my Bok

Post by skow69 » Sun Dec 27, 2015 12:38 pm

joeymac wrote:I wouldn't describe the air suction as dramatic by any means.
Now, if you actually had no pressure relief it might get interesting and twist up your boiler some.
I wonder if a standard keg can support vacuum distillation :egeek:
Given the shape of a sanke keg, it should work great under vacuum. A corney keg won't without reinforcement. They collapse around 29 inHg. A sanke has those ribs to stiffen it. For our purposes you really can't go past about 28 inHg (50 torr) anyway because that is where the distillate, at ~50% ABV starts to boil off at room temperature.
Distilling at 110f and 75 torr.
I'm not an absinthe snob, I'm The Absinthe Nazi. "NO ABSINTHE FOR YOU!"

Post Reply