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I have put some SPP at the bottom of my 3 inch wide by 10inch long shotgun condenser on my VM still in an attempt to slow down the speed of the vapor. With the valve closed to the product and attempting full reflux there is an interesting thing happening. The shotgun condenser like this is operating like a product condenser and the product is just overflowing the top not as a gas but as a liquid.

Any theories on this? I am guessing the SPP is acting like a blockage for the liquid but not the gas, but why? Under the shotgun is not liquid it is gas (got a sight tower there) so it isn't like the whole column is flooded.

that should really blur the cuts

and blockages speed up vapor not slow it... (unless condenser output is near totally blocked with soaked SPP)

Try a colder shotgun condenser with no blockage and an angled liebig final condenser rather than SPP

I'd use SPP in the shotgun water jacket before i'd use it at the end of my condenser.

Reverend Newer wrote:that should really blur the cuts

and blockages speed up vapor not slow it... (unless condenser output is near totally blocked with soaked SPP)

Try a colder shotgun condenser with no blockage and an angled liebig final condenser rather than SPP

Well I know how to stop it from happening, I am just curious why it is happening. If my condenser wasn't cold enough then gas would be escaping instead of liquid.

Original post is a bit confusing, if you are talking a sight tower, i see now this is a deflag reflux condenser not a product condenser? I guess ya'd lower the level of the SPP to avoid the overflow in the deflag.

I have not used SPP but I read it is so efficient, being that close to the deflag condenser, it is sure to flood as you describe.


If you have a 10" deflag reflux condenser on a 3" pipe using SPP.... this post seems trollish and a joke, prolly why i'm the only one replying.

Ya guys got me!

I have a shotgun condenser at the top of my tower, and just before that is a 3x3x2 outlet that goes to my product condenser which is a 2inch by 15inch shotgun condenser. When I shut off the butterfly valve to the product output and attempt a full reflux I get product being output over the top of my reflux condenser. Liquid not gas. And it is purely because of the SPP at the bottom because without it it just refluxes like normal. I just found it strange that this is happening and would like to know why it is happening.

Is the top of shotgun open to atmosphere?

I have not seen a shotgun reflux condenser used fully-above the output port with SPP in the bottom of it.



Love to see some pics, prolly clear it up fast



The reflux condenser goes below the 2" output or at minumum halfway blocking the 2 inch output. Adjust accordingly with position or coolant flow.

Shotgun is open to atmosphere of course, otherwise product couldn't flow out of it
Attached is pic, top of the still is the 3 inch shotgun condenser used for reflux.

That upturn in the pipe after your reflux condenser goes so high and where the butterfly is located confuses me also.


Looks by the stainless steel and cleanliness of your rig I am just retarded and out of my league.


If I had to guess, I'd say that the upturn in your output causes more resistance to vapor flow and like electricity, vapor will take the path of least resistance so it keeps trying to go out the reflux shotgun and floods it.


Now I see why you have SPP in the bottom, to force vapor through the upturn. Not sure how that butterfly seals things off, but vapor will choose 3 inch pipe in straight line over upturned 2" output it seems

Reverend Newer wrote:That upturn in the pipe after your reflux condenser goes so high and where the butterfly is located confuses me also.

Just there to stop any liquid bubbling into the product line. The top sight tower bubbles with boiling liquid in this design.

Reverend Newer wrote: If I had to guess, i'd say with that upturn in your output it causes more resistance to vapor flow and like electricity, vapor will take the path of least resistance so it keep trying to go out the reflux shotgun and floods it.

The product line has nothing to do with this because the top shotgun condenser only floods when I have the product line turned off. Basically I have a liquid in my main column, then it goes to gas just before the shotgun condenser and for some reason SPP in the shotgun condenser is another liquid layer in this pipe that flows out the top instead of refluxing. The SPP in the shotgun condenser is somehow stopping liquid flowing back down the pipe, and somehow still letting new gas in.

Probably just because SPP is so efficient at speading out liquid/vapor it clogs itself up when pushed too hard with full liquid in column. I imagine you ran it without the SPP inside the reflux shotgun as well?

I guess SPP doesn't drain as fast as it lets vapor pass?


I really have not seen a butterfly on the output like this before, intriguing.

Sounds like w/SPP in you're running it with too much power. The deflag tubes are much smaller volume than your 3" column so they flood with less power. Liquid is trying to drain down and the vapor keeps pushing it up due to amount of power from below.

Flooding of a 3" SPP packed column and flooding of five or seven 1/2" SPP packed deflag tubes is a big difference in throughput capability.

The lower volume area in the deflag also speeds up the vapor which compounds the issue from below.

Does it work effectively without the SPP in the deflag?

Cheers!
-j

hoochlover wrote:...With the (VM) valve closed to the product and attempting full reflux...and the product is just overflowing the top not as a gas but as a liquid.

Any theories on this?

I am guessing the SPP is acting like a blockage for the liquid but not the gas, but why? Under the shotgun is not liquid it is gas (got a sight tower there) so it isn't like the whole column is flooded.

Yep, you’re flooding the deflag with the packing. Get rid of it.

Condensate is supposed to fall back through the packing in the column (and reflux/reboil). If you get vapor out of the top, then you’re overdriving the condensing power of your RC. Two ways to resolve this, 1) reduce heat input, or 2) increase coolant flow rate.

As noted, stuffing the RC with packing will cause the vapor to speed up, not slow down. As a result, it can “entrain” liquid in the vapor stream.

However, copper packing has a very good heat transfer coefficient so copper scrubbies will incease the conducting surface area for transfer of heat from rising vapors to the water jacket. This can actually increase condensation. But again, if the vapor velocity is too high, the newly condensed product can be “blown out” the top with escaping vapors.
ss

Looking at the foto of your rig, I would put the u-bend before the 90* elbow. Put it into the horizontal plane with the elbow turning from horizontal into your vertical product condenser.

The way it is now, there is a natural (bouyant) force to cause the vapors to rise into the shotgun deflag, hence your motivation to add packing for resistance to vapor flow. The pressure instability can be corrected by laying the u-bend horizontal, or even eliminating it all together. There really is no reason you need it in the vapor flow path....go straight from the butterfly VM valve to the 90* elbow and into the product condenser.

Also, seeing that your still is all stainless, I assume your SPP is copper...possibly even copper scrubbies?
ss

jonnys_spirit wrote:Sounds like w/SPP in you're running it with too much power. The deflag tubes are much smaller volume than your 3" column so they flood with less power. Liquid is trying to drain down and the vapor keeps pushing it up due to amount of power from below.

Flooding of a 3" SPP packed column and flooding of five or seven 1/2" SPP packed deflag tubes is a big difference in throughput capability.

The lower volume area in the deflag also speeds up the vapor which compounds the issue from below.

Does it work effectively without the SPP in the deflag?

Cheers!
-j

Yes works fine without SPP, it floods with the SPP in there at half the power the shotgun condenser can put down normally. The shotgun condenser can normally handle around 3KW of heat when it is empty but I have 4.4KW at my disposal so wanted to try different ways to get it to put down 4.4KW of heat. With SPP in there it just fills with alcohol at around 1.5KW of heat.

There is a vacuum type thing going on because when I open the product valve it makes a suction type sound and then it all drains from the shotgun condenser. I think this has something to do with the SPP more than anything else because it doesn't do it with other types of packing in there. Somehow the SPP is able to hold the liquid up there and still let gas come in and let none drain back down.

still_stirrin wrote:Looking at the foto of your rig, I would put the u-bend before the 90* elbow. Put it into the horizontal plane with the elbow turning from horizontal into your vertical product condenser.

The way it is now, there is a natural (bouyant) force to cause the vapors to rise into the shotgun deflag, hence your motivation to add packing for resistance to vapor flow. The pressure instability can be corrected by laying the u-bend horizontal, or even eliminating it all together. There really is no reason you need it in the vapor flow path....go straight from the butterfly VM valve to the 90* elbow and into the product condenser.

Also, seeing that your still is all stainless, I assume your SPP is copper...possibly even copper scrubbies?
ss

It did the same thing before I added the 90 degree turn, I added that just to ensure no liquid bouncing around entered the product gas path. There is a quite vigorous boiling action occurring in the top sight tower after the SPP ends. But this T design I use I am not sure if its optimal for a VM still, it seems like a delicate balance when it comes to pressure to the shotgun condenser or pressure to the product. The butterfly valve is also useless for the minute amount of control you need so I will need to find another solution for that.

And no my SPP is stainless, I don't use copper. No need for it for me.

I am getting around 5L of 80% ABV per hour through this thing, but when I get near azeo the speed is just horrendous so I still need to do some tweaking.

jonnys_spirit wrote:Sounds like w/SPP in you're running it with too much power. The deflag tubes are much smaller volume than your 3" column so they flood with less power. Liquid is trying to drain down and the vapor keeps pushing it up due to amount of power from below.

Flooding of a 3" SPP packed column and flooding of five or seven 1/2" SPP packed deflag tubes is a big difference in throughput capability.

The lower volume area in the deflag also speeds up the vapor which compounds the issue from below.

Does it work effectively without the SPP in the deflag?

Cheers!
-j

Yup I think Jonny's nailed it . Even if you had 6 x 3/4" tubes in your Shotty , that's a cross sectional area of 2.6 square "

A 2" column has a cross sectional area of 3.14 Square " .........so in effect you are running a column full of spp at under 2" .

It is pretty common knowledge that the maximum power before flooding in a 2" column is around 2Kw ......so its not surprising that you are getting flooding at around 1.5Kw .

Good experiment , thanks for posting your results , but it would appear to be a fail using SPP .

Take it out and just use less power or get a longer and preferably Copper Shotty if you want to run with more power

The SPP packs tighter than say, scrubbies. So the SPP will retain/hold up the liquid and the gas will pass up through it. This creates a minor amount of pressure in the boiler.

I assume you're trying to make your condenser more efficient.

Try a small amount of SS Scrubbie to replace the SPP in a condenser. The scrubbie will let the liquid flow downward.