Shotgun reflux condenser for a 3" column

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der wo
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Re: Shotgun reflux condenser for a 3" column

Post by der wo »

How do you now it's 2600W? Because of the scale you wrote by yourself onto the controller? Ever checked the numbers? I wouldn't trust, that it is such symmetrical as you wrote it on the scale.

How did you decide to connect the condenser? Water flow down or up? If down, are you sure, there aren't bubbles in the condenser?

Water in and out temperature?

Did you look from above into the condenser? Is there flooding? Or did you hear flooding?
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Re: Shotgun reflux condenser for a 3" column

Post by still_stirrin »

Sergiolis,

When you built the shotgun, did you put any baffles in the tube bank so the water doesn't simply channel from the inlet to the outlet? I see your outlet and inlet are aligned and you have many tubes in the tube bank helping to direct the water flow from inlet to outlet instead of circulating around all of the tubes in the bank. Although the water will fill the cavity, the flow resistance will cause the flow to follow the path of least resistance, in this case directly from inlet to outlet.

Also, your shotgun is all stainless steel. Stainless has a lower coefficient of thermal heat transfer (conduction) than copper. This will make a difference on the efficiency of the heat exchanger. It could be overcome by a higher coolant flow rate. But, if the water is channeling, it will not perform as expected and intended.
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sergiolis
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Re: Shotgun reflux condenser for a 3" column

Post by sergiolis »

Hi still_stirrin
the column is SS but all the tubes inside the shotgun and the base ends are copper.
But it's true I didn't add baffles....
I can do it if it is necessary but it is a tonne of work to rebuild completely this condenser.
But if you think it will work I will do it...
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Re: Shotgun reflux condenser for a 3" column

Post by sergiolis »

sorry der wo, I didn't see your post,
I tried both, water in at the top and water in at the bottom and they were acting similar.
You are right about knowing the real power with that scale. Probably is not proportional but as I'm working always with it I can tell you is quite sensitive and staggered . At least until the maximum power I've been working (4000w) in my last feints run.
Even with cold water temperature out, vapours were scaping....
Right now I will try it again and I will watch if there is flooding...
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der wo
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Re: Shotgun reflux condenser for a 3" column

Post by der wo »

Is it a water run or with alcohol?

The vapor is little puffs or is it steady?
Are there shotgun tubes where never comes vapor out and other where always?
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Re: Shotgun reflux condenser for a 3" column

Post by sergiolis »

It is an alcohol run,
I will start again the run and I will tell you...
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Re: Shotgun reflux condenser for a 3" column

Post by sergiolis »

Water out is only at 27ºC. Just 2400W but vapour is scaping in the tube where it is ' water in ' of the shotgun and in the tube behind this one..
If I push till 2600w I can see vapour in the tubes around these ones too... so predominantly the side where water is connected.
Last edited by sergiolis on Sun Apr 02, 2017 9:05 am, edited 1 time in total.
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still_stirrin
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Re: Shotgun reflux condenser for a 3" column

Post by still_stirrin »

sergiolis wrote:...the column is SS but all the tubes inside the shotgun and the base ends are copper.
Well, this is good news. The copper vapor tubes are proper for improved function.
sergiolis wrote:...But it's true I didn't add baffles.... I can do it if it is necessary but it is a tonne of work to rebuild completely this condenser. But if you think it will work I will do it...
Well, it depends if you're wanting to increase the heat input and be confident that you don't vent vapors, then you can run it as it is built. But, if you are concerned about venting vapors, then improving the efficiency would be in order.

Your decision....
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Re: Shotgun reflux condenser for a 3" column

Post by sergiolis »

:) You are fun still_stirrin, I think I,d rather prefer not smelling alcohol vapour around my kitchen...

Correct me if I'm wrong. Supposedly this is one of the most effective condensers for a homedistiller.... As you are a man of experience...
I just want a condenser able to knock 5000W
Do i need to fix this shotgun or do I have easier options?
Anyway part of the problem may be that the holes to connect water are facing a tube and not between 2 tubes... Maybe this situation helps to channel water... I would fix this too...
If this shotgun may work how many baffles do you recommend?
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Re: Shotgun reflux condenser for a 3" column

Post by der wo »

Sorry, I hope members with shotguns can help.

The only thing I think about is, if 12" simply is too short for over 4000W. Regardless of how many tubes or single or double coil.
Is a shotgun more efficient than a coil? I am not sure. If your coil was able to handle 4000W, buy 18" instead of 12" and a longer coil. I know, it was much work with the shotgun...
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Re: Shotgun reflux condenser for a 3" column

Post by sergiolis »

I can't go longer because I would need another SS spool tube.
I have 2 options:
To fix the shotgun adding 3 baffles or to wind a double coil. I've found on Alibaba SS 1/4" corrugated pipe.
Building a shotgun with baffles with the tools I have would be a nightmare so I will go for the 1/4" CSST.
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Re: Shotgun reflux condenser for a 3" column

Post by cranky »

I think the CSST is a lot more efficient than you give it credit. First it is thin walled meaning better heat transfer, second is it has a ton of surface area because of the corrugations which means more cooling area. If you want to increase the cooling power of it stick some scrubby between some coils. Dad has a thread about it with his CCVM (I hope I got that right). One alternative I can think of if you have the height is go ahead and get another spool and add that Dimroth above the shotgun and you will be able to knock down anything.
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Re: Shotgun reflux condenser for a 3" column

Post by RedwoodHillBilly »

cranky wrote:I think the CSST is a lot more efficient than you give it credit. First it is thin walled meaning better heat transfer, second is it has a ton of surface area because of the corrugations which means more cooling area. If you want to increase the cooling power of it stick some scrubby between some coils. Dad has a thread about it with his CCVM (I hope I got that right). One alternative I can think of if you have the height is go ahead and get another spool and add that Dimroth above the shotgun and you will be able to knock down anything.
Agreed. The reflux condenser on my 3" CCVM has fewer coils than yours, but it has scrubbies in the coils. It will easily knockdown 5500w without all that much water flow.
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Re: Shotgun reflux condenser for a 3" column

Post by sergiolis »

I will order 1/4" CSST (DN6) to build a double coil, but it comes from China so I'll have to wait about a month...
Meanwhile I will try to continue the run this evening with the dimroth of the picture (DN8). Actually it has 3 SS scrubbers in its upper half.. But as I said about 4000W it was saturated in my first run.... but I'll try it again...
I know they are very efficient but I decided to try a shotgun because I wanted to knock more power than 4000W or at least to be able if I need it.
Thanks guys
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Re: Shotgun reflux condenser for a 3" column

Post by RedwoodHillBilly »

Perhaps you could add some more scrubbies in the bottom half. You should get more heat transfer that way.
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Re: Shotgun reflux condenser for a 3" column

Post by sergiolis »

Some details about my second run.
Well I had to disassemble the shotgun. It was a bit frustrating. But as still_stirrin clearly pointed out there was channeling and it wasn't working properly. Besides that water entering the shotgun was quite channeled because it was immediately facing a tube inside the shotgun and I suppose it could flow much better if is set between 2 tubes. Well it was my first attemp but I will try to make a new one with 3 baffles inside. The difficult part of making a shotgun is that the holes of all the discs must be perfectly aligned. But I think I will be able to drill 5 sheets (2 ends + 3 baffles) at the same time if the sheets are properly attached. So as I'm quite stubborn I will try it again.
So I placed my dimroth again with about 5 SS scrubbers inside the coil. It is confirmed, its maximum capacity it is about 4100-4200W in my scale.
Working at that power, water out was at 43.5ºC and some peaks at 48ºC when my neighbour took a shower. Collecting at 56 ml/min., 95.3 % abv. Great! I'm so happy because the performance was quite good and faster than with my 2" column , but....
It could be better! As a said to maximise effectiviness of SPP the whole rig should be "boiling" and one should see bubbles or the liquid boiling mixture near the top of the packing.... (well if you have a sight glass) So definitely I need more power and i need a better condenser too.
Now I'm waiting for a 20" SS spool tube and I will build a longer dimroth with DN8 CSST.
Besides that, I will build a new improved shotgun in relation to my first one.
I would like to compare the efectiviness of both CSST and shotgun.
Supposedly the plan will continue to be refined! or not.... :ewink:
Thanks a lot guys!!
The good news is that we learn more when we fail than when we are successful!!!!
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Re: Shotgun reflux condenser for a 3" column

Post by sergiolis »

Finally I bought a longer 20" SS spool tube, but the thing is now I need a longer CSST DN8 too.... Supposedly I found CSST 1/4" (DN6) but it was an error of the seller because actually is DN8 (12mm diameter). Looks like smaller than DN8 doesn't exist... So the possibility of a double coil is now aborted and the only choice I have is to make it longer... But I think 20" with a single coil will be more than enough...
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Re: Shotgun reflux condenser for a 3" column

Post by sergiolis »

I will use a longer Dimroth condenser but eventually I would like to test a shotgun as a reflux condenser.
In reference to water surface to vapour surface ratio I was searching some hints but I didn't find it. There is a lot of info about shotguns as a product condenser but not as a reflux condenser...
I'm thinking about these 2 options but is really difficult to know wich one could work better. Tubes are 15mm and 12mm OD.
It is just an experiment to compare the efficiency between a shotgun and a single coil with similar lenght.
Any opinions will be very appreciated...
shotgun WEB.jpg
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Re: Shotgun reflux condenser for a 3" column

Post by still_stirrin »

The water flow "area" is not the critical measurement. What you want, is the area that the water contacts the vapor tubes (a series of cylinders) to be greatest. So, the shotgun with more vapor tubes would have more contact area than the option with fewer tubes. As a result, it (the fist option shown) is the better option (for efficiency). The vapor flow area (sum of tube diameters) is inversely proportional to vapor velocity, so again, more vapor tubes is better for efficiency because it increases the dwell time the vapor makes with the tubes to transfer its heat to the tubes.

The mechanisms of heat transfer are "convection" for the vapor to transfer its heat to the vapor tubes. Then, "conduction" of heat through the tube bank walls. And finally, "convection" again for the water to take the heat away from the vapor tube bank. All mechanisms rely on temperature difference as the "motive force" to generate the heat transfer.

Also, the dwell time in both fluids (vapor and coolant) dramatically affects the efficiency of the heat transfer. All you can do as a designer/builder is to maximize these design considerations to balance the overall heat transfer equation. An education in mechanical engineering would teach you these physical "laws".
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Re: Shotgun reflux condenser for a 3" column

Post by sergiolis »

Great explanation still_stirrin and really helpful.
Then I will try the first option above.
Unfortunately my mechanical engineering knowledge leaves much to be desired... So my best option is trial and error. Anyway it is just an experiment but I'm very excited about the results and I already have the materials to build it.
According to your advice my first attempt would be the best but the tubes are too tight for my tools and skills so I decided to reduce to some extent the tubes surface.
Ohhh and I will put 3 baffles, so every 7 cm water will be diverted. (total lenght 28cm)
Thank you for your help!
Eventually I will post the results.
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Re: Shotgun reflux condenser for a 3" column

Post by allanbradl »

So where are you now on your baffle design? In the same boat and curious.
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Re: Shotgun reflux condenser for a 3" column

Post by sergiolis »

hi allanbradl,
I finished the shotgun with 3 baffles and the new design looks much more interesting but there are some small tiny leaks at the ends because I just tried to weld the copper ends with tin/silver wire to the SS spool tube but unfortunately is not so easy to weld SS with copper with this technique. I will try it again using electrode welding but to do that I need to visit a friend who has the welding machine.
Meanwhile i did another run with a longer CSST coil and I'm very glad with the results.
https://www.youtube.com/watch?v=sU6W1xh ... e=youtu.be" onclick="window.open(this.href);return false;" rel="nofollow
The video shows the run at hearts, 3600W, 70ml/min.
Don't ask me why but this time I could see the bubbles at the top at 3600W. The adequate range wattage is between 3500-3700W. The longer coil works perfect, in fact looks more than I need but it is great to have more condensing capacity than you need...
48cm coil.jpg
As soon as I fix the shotgun I will post the results
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sergiolis
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Re: Shotgun reflux condenser for a 3" column

Post by sergiolis »

I tried copper-silver rods to braze the copper ends to the SS shotgun wall but it's still too difficult... so I will change to copper....It will take a while meanwhile the copper tube arrives but sooner or later I will get it... and I will post the results compared to the coil...
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Re: Shotgun reflux condenser for a 3" column

Post by allanbradl »

Thanks a lot for sharing the ideas, On a safe side , should I make reflux condenser a tad longer?
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Re: Shotgun reflux condenser for a 3" column

Post by sergiolis »

Hi allanbradl,
If you don't see vapours escaping don't worry about it...
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