Condenser power (calculator value issue)?

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Benredbeard
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Condenser power (calculator value issue)?

Post by Benredbeard »

My propane burners put out up to 200,000 BTUs which is like 58,000 watts. Obviously I would never run that, and they throttle WAY back, but this means that I can't easily use the condenser calculator tool since I have no idea how many equivalent watts I'll typically push.

Is there a general wattage recommended for wash volume or intended purpose that I could use as a yardstick?

Or, what would say a 10-gallon stripping run beg for heating? Does anyone just make a vanilla 24" 1/2" in 3/4" Liebig and keep a shotgun in reserve for stripping?

Any pointers appreciated.
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OtisT
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Re: Condenser power (calculator value issue)?

Post by OtisT »

FYI, the volume of your boiler has nothing to do with these questions. It’s all about how much power/heat you apply, how much heat your still looses to the air (More insulation = less heat loss) and what your PC can knock down. If the amount of power reaching your PC is greater than it can handle, the remaining power comes out your PC as vapor (bad.)

Since you can’t measure wattage, what wattage you need to run at is irrevelant.

For stripping, simply put a heavy flow of water through your Liebig then adjust the heat so you are just shy of vapor escaping your PC. No magic there. FYI, my guess is that this will be somewhere near 2000 to 2500 watts equivalent. My 3/4” vapor path x 24” jacket Liebig will safely handle about 3500 watts and not much more.

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Benredbeard
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Re: Condenser power (calculator value issue)?

Post by Benredbeard »

OtisT wrote:
For stripping, simply put a heavy flow of water through your Liebig then adjust the heat so you are just shy of vapor escaping your PC. No magic there. FYI, my guess is that this will be somewhere near 2000 to 2500 watts equivalent. My 3/4” vapor path x 24” jacket Liebig will safely handle about 3500 watts and not much more.

Otis
Understood. For building my condenser, I'm hoping the brain trust can loan me some ballpark figures. .75"x24" for the vapor path: is that on the wide end? Thanks for the data point!
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Expat
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Re: Condenser power (calculator value issue)?

Post by Expat »

Benredbeard wrote: Understood. For building my condenser, I'm hoping the brain trust can loan me some ballpark figures. .75"x24" for the vapor path: is that on the wide end? Thanks for the data point!
Sizing would depend on how much power ergo vapor it needs nock down.

Another data point. I over built my condenser, 48". 3/4" over 1/2". In testing I was able to knock down 5500watts of water steam without issue. The length adds a lot to the efficiency.
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Bearpig
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Re: Condenser power (calculator value issue)?

Post by Bearpig »

I think either the condenser calculator vastly overestimates the size of condenser you need, or the addition of an inner coil to spin the water around the vapor tube vastly increases it's efficiency.
Either way after following the calc I ended up making an 8 foot liebig condenser (still smaller than the calc recommended) for my 5kw burner and 15G still, which ended up being so insanely overpowered that the tiniest trickle of water had my condensate coming out ice cold... which would have been great except that an 8 foot liebig is a really awkward size :shock:

I chopped the condenser in half (and made a second liebig for a friend with the other half) and increased the water flow a little and everything was perfect.

So I'd recommend you size your condenser as large as you can for your available space, and then tweak water flow to get the cooling you need. Make sure you add an inner spiral of copper soldered to the vapor tube since it seems to have a very significant impact on liebig efficiency. If you need more than 4-5 feet then start looking into other condenser designs like shotguns that are much less awkward to get around. My still now has a 42" SS shotgun that does the job of the copper liebig in a much more compact size.

If you need something to knock down a LOT of vapor you could look into buying/building some shotgun condensers with tri-clamps, that way if you need more cooling you can just add another one and daisy-chain the water flow, and you end up with a modular setup. Just a thought.
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Twisted Brick
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Re: Condenser power (calculator value issue)?

Post by Twisted Brick »

OtisT wrote:FYI, the volume of your boiler has nothing to do with these questions. It’s all about how much power/heat you apply, how much heat your still looses to the air (More insulation = less heat loss) and what your PC can knock down. If the amount of power reaching your PC is greater than it can handle, the remaining power comes out your PC as vapor (bad.)

Since you can’t measure wattage, what wattage you need to run at is irrevelant.

For stripping, simply put a heavy flow of water through your Liebig then adjust the heat so you are just shy of vapor escaping your PC. No magic there. FYI, my guess is that this will be somewhere near 2000 to 2500 watts equivalent. My 3/4” vapor path x 24” jacket Liebig will safely handle about 3500 watts and not much more.

Otis
Also, as the temperature of your coolant increases, the efficiency of your condenser decreases and your takeoff temp rises. Like OtisT recommends, just power your boiler to the point your liebig leaks vapor and back off. If you can't live with the speed, build a shotgun.

Here is another discussion on almost the same thing.
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cranky
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Re: Condenser power (calculator value issue)?

Post by cranky »

My liebig is 36" long but I also have a 24" extension should the need arise... The need has never arisen. My 36" condenser knocks down everything 5500W can throw at it but I do have a wire coiled inside the water jacket and another one inside the vapor path.
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