ive read a bit about this in various threads, but ive gotten various information that is sometimes contradictory
say i have a 2 inch column, and it reduces to half inch and leads to my liebig, which also is a half inch vapor path. as i understand it this makes the vapor move alot faster. which can make vapor blow past a liebig if it isnt sized long enough and is at a vertical angle especially, even if the water is cold. that i learned from experience. though that issue is long handled, the reason i ask though is im trying to build a new thumper setup and mostly use parts i have around as scrap to complete the project. as it would be, i could reduce to half inch for a short distance, and then go to larger diameter for as much as possible, or or should i just go ahead and run half inch right into the thumper down tube and not bother going back up to a larger bore tubing after the choke point. does opening back up and lowering the vapor speed after a choke down to half inch diameter for a couple inches of the length behoove me?
basically, if that didnt make sense, should i use a larger vapor path after a choke point if possible? or does it not matter and just go easier and keep it narrow? what difference would this make other than condenser efficiency?
thanks in advance yall
AMELIH
"choke points" in vapor path.
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"choke points" in vapor path.
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- still_stirrin
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Re: "choke points" in vapor path.
Shucks, Drew Brees couldn’t hang on with the W. But, they played a good game.
So, a “choke” point will act as an orifice in a piping network causing a pressure drop across the narrowed line. In a still, this causes the pressure to increase in the boiler in order to maintain flow through the piping.
But, if you keep the discharge line through the network after the choke small too, you’ll see the vapor accelerate in velocity but not necessarily increase in mass flow. Said a different way, the vapor throughput will choke down (less output) but the velocity will increase, making it difficult to condense the vapors adequately. You may get blowby even with lower boiler heat.
So, the best thing to consider for vapor flow is to keep it around 20 feet per second, faster and the pressure will drop through the line. But since the outlet can’t be less than atmospheric, what happens is that the source (boiler) must pressurize in order to produce vapor flow. Larger diameter lines will help keep the velocity low so the vapor can transfer its heat to the condenser better. This is the “dwell time” the vapor experiences as it passes into the Liebig.
With a 1/2” vapor tube from a 2” still riser, the vapor flow will be limited by the 1/2” diameter. But reducing to 1/2” just before the inlet to the Liebig will minimize the flow restriction. A long 1/2” diameter vapor tube in a Liebig will work because of the surface area of the vapor tube. However, if the velocity is too fast, the dwell time is short and it can result in vapor puffing out the outlet. Shotgun condenser resolve this paradox by increasing the conducting surface while still providing the flow area to keep the velocity slow (relatively).
So, for your proposal...keep the vapor tube as large diameter as you can into the thumper and even out of the thumper. Then, just before the product condenser, reduce to your Liebig’s vapor tube diameter. Of note, there are many designs on the site that have 2” risers that reduce to 1” as they pipe to the thumper. Then, the vapor outlet from the thumper is maintained at 1” until the Liebig inlet. These work as a workable compromise where the vapor speed is limited by the 1” diameter tubes as long as possible.
If you look into the designs, you’ll see many of these stills, especially when the boiler and thumper are both kegs. It just works nice that way.
I don’t know if I’ve answered your questions, or created more. But I tried.
ss
So, a “choke” point will act as an orifice in a piping network causing a pressure drop across the narrowed line. In a still, this causes the pressure to increase in the boiler in order to maintain flow through the piping.
But, if you keep the discharge line through the network after the choke small too, you’ll see the vapor accelerate in velocity but not necessarily increase in mass flow. Said a different way, the vapor throughput will choke down (less output) but the velocity will increase, making it difficult to condense the vapors adequately. You may get blowby even with lower boiler heat.
So, the best thing to consider for vapor flow is to keep it around 20 feet per second, faster and the pressure will drop through the line. But since the outlet can’t be less than atmospheric, what happens is that the source (boiler) must pressurize in order to produce vapor flow. Larger diameter lines will help keep the velocity low so the vapor can transfer its heat to the condenser better. This is the “dwell time” the vapor experiences as it passes into the Liebig.
With a 1/2” vapor tube from a 2” still riser, the vapor flow will be limited by the 1/2” diameter. But reducing to 1/2” just before the inlet to the Liebig will minimize the flow restriction. A long 1/2” diameter vapor tube in a Liebig will work because of the surface area of the vapor tube. However, if the velocity is too fast, the dwell time is short and it can result in vapor puffing out the outlet. Shotgun condenser resolve this paradox by increasing the conducting surface while still providing the flow area to keep the velocity slow (relatively).
So, for your proposal...keep the vapor tube as large diameter as you can into the thumper and even out of the thumper. Then, just before the product condenser, reduce to your Liebig’s vapor tube diameter. Of note, there are many designs on the site that have 2” risers that reduce to 1” as they pipe to the thumper. Then, the vapor outlet from the thumper is maintained at 1” until the Liebig inlet. These work as a workable compromise where the vapor speed is limited by the 1” diameter tubes as long as possible.
If you look into the designs, you’ll see many of these stills, especially when the boiler and thumper are both kegs. It just works nice that way.
I don’t know if I’ve answered your questions, or created more. But I tried.
ss
My LM/VM & Potstill: My build thread
My Cadco hotplate modification thread: Hotplate Build
My stock pot gin still: stock pot potstill
My 5-grain Bourbon recipe: Special K
My Cadco hotplate modification thread: Hotplate Build
My stock pot gin still: stock pot potstill
My 5-grain Bourbon recipe: Special K
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Re: "choke points" in vapor path.
If you want to calculate your vapor speed, go to the homedistiller.org home page, select “calcs” on the top, then look in the “calcs by RAD” page. Bottom of that page has a calculator for calculating vapor speed. Otis
Otis’ Pot and Thumper, Dimroth Condenser: Pot-n-Thumper/Dimroth
Learning to Toast: Toasting Wood
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Learning to Toast: Toasting Wood
Polishing Spirits with Fruitwood: Fruitwood
Badmotivator’s Barrels: Badmo Barrels
Re: "choke points" in vapor path.
You answered my questions adequately and more sir. This is exactly what I was trying to understand. Guess I'm gonna go to the commercial plumbers shop Tuesday when they're open and get what I need to keep it big bore. Maybe try to run it 2 inch to 1.5 inch into the thumper.still_stirrin wrote:Shucks, Drew Brees couldn’t hang on with the W. But, they played a good game.
So, a “choke” point will act as an orifice in a piping network causing a pressure drop across the narrowed line. In a still, this causes the pressure to increase in the boiler in order to maintain flow through the piping.
But, if you keep the discharge line through the network after the choke small too, you’ll see the vapor accelerate in velocity but not necessarily increase in mass flow. Said a different way, the vapor throughput will choke down (less output) but the velocity will increase, making it difficult to condense the vapors adequately. You may get blowby even with lower boiler heat.
So, the best thing to consider for vapor flow is to keep it around 20 feet per second, faster and the pressure will drop through the line. But since the outlet can’t be less than atmospheric, what happens is that the source (boiler) must pressurize in order to produce vapor flow. Larger diameter lines will help keep the velocity low so the vapor can transfer its heat to the condenser better. This is the “dwell time” the vapor experiences as it passes into the Liebig.
With a 1/2” vapor tube from a 2” still riser, the vapor flow will be limited by the 1/2” diameter. But reducing to 1/2” just before the inlet to the Liebig will minimize the flow restriction. A long 1/2” diameter vapor tube in a Liebig will work because of the surface area of the vapor tube. However, if the velocity is too fast, the dwell time is short and it can result in vapor puffing out the outlet. Shotgun condenser resolve this paradox by increasing the conducting surface while still providing the flow area to keep the velocity slow (relatively).
So, for your proposal...keep the vapor tube as large diameter as you can into the thumper and even out of the thumper. Then, just before the product condenser, reduce to your Liebig’s vapor tube diameter. Of note, there are many designs on the site that have 2” risers that reduce to 1” as they pipe to the thumper. Then, the vapor outlet from the thumper is maintained at 1” until the Liebig inlet. These work as a workable compromise where the vapor speed is limited by the 1” diameter tubes as long as possible.
If you look into the designs, you’ll see many of these stills, especially when the boiler and thumper are both kegs. It just works nice that way.
I don’t know if I’ve answered your questions, or created more. But I tried.
ss
Does this pressure increase pose any actual ris though?I
Also I'm not ready to talk bout football. Robbed. That hit. Ugh. Never would have went to OT.
Otis: I do remember that calc. I'll have to check it out.
Good looking out gentlemen.
<no stopping to corner anytime [] no parking passenger zone>
When people tell me I'll regret that in the morning, I sleep till noon.
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- still_stirrin
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- Joined: Tue Mar 18, 2014 7:01 am
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Re: "choke points" in vapor path.
An increase in boiler pressure can cause system leaks if your boiler and piping can’t support the pressure. But this probably won’t be a problem if you have a keg and tri-clover attachments.
But an increase in boiler pressure will also raise the boil temperatures and that can affect the quality of the spirits because it can smear more. Its the opposite effect of vacuum distilling where the boiling points are depressed resulting in better separation of the fractions. But your boil pressure increase will be small such that you probably can’t measure it unless you have a manometer...just inches of water column above ambient atmospheric.
ss
But an increase in boiler pressure will also raise the boil temperatures and that can affect the quality of the spirits because it can smear more. Its the opposite effect of vacuum distilling where the boiling points are depressed resulting in better separation of the fractions. But your boil pressure increase will be small such that you probably can’t measure it unless you have a manometer...just inches of water column above ambient atmospheric.
ss
My LM/VM & Potstill: My build thread
My Cadco hotplate modification thread: Hotplate Build
My stock pot gin still: stock pot potstill
My 5-grain Bourbon recipe: Special K
My Cadco hotplate modification thread: Hotplate Build
My stock pot gin still: stock pot potstill
My 5-grain Bourbon recipe: Special K
- Saltbush Bill
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Re: "choke points" in vapor path.
still_stirrin wrote:An increase in boiler pressure can cause system leaks if your boiler and piping can’t support the pressure.
If your boiler is building pressure ..you have done it all wrong to start with ..go back to the beginning and start again. Disregard any other information given.
Re: "choke points" in vapor path.
makes perfect sense
thank you again kind sir
Off topic - i cant facebook today because of football, omg.
thank you again kind sir
Off topic - i cant facebook today because of football, omg.
<no stopping to corner anytime [] no parking passenger zone>
When people tell me I'll regret that in the morning, I sleep till noon.
When people tell me I'll regret that in the morning, I sleep till noon.
Re: "choke points" in vapor path.
peep my thread in the construction site, went ahead and purchased some stuff to do it proper.still_stirrin wrote:An increase in boiler pressure can cause system leaks if your boiler and piping can’t support the pressure. But this probably won’t be a problem if you have a keg and tri-clover attachments.
But an increase in boiler pressure will also raise the boil temperatures and that can affect the quality of the spirits because it can smear more. Its the opposite effect of vacuum distilling where the boiling points are depressed resulting in better separation of the fractions. But your boil pressure increase will be small such that you probably can’t measure it unless you have a manometer...just inches of water column above ambient atmospheric.
ss
viewtopic.php?f=50&t=73476
so much thanks SS, you da man.
<no stopping to corner anytime [] no parking passenger zone>
When people tell me I'll regret that in the morning, I sleep till noon.
When people tell me I'll regret that in the morning, I sleep till noon.