Reliquifying flash

[mminford]

Is there an inexpensive way to trap flash and reliquify it? I'm faily new out of college and I know that you can either use a refrigeration system or a compressor. Which is the best method and most inexpensive way?

 

[iainuts]

Can you be a bit more specific? Are you taking gas out of the vapor side of a cryogic tank? What kind of gas? What pressure? Why do you want to reliquify it? Where do you want to put it once it's reliquified?

 

[mminford]

Argon venting from a dewar. Argon is expensive we would like to capture it. Pressure could range anywhere from 50-250 psig. Once it's reliquified, we want to put it back in a bulk tank.

 

[iainuts]

Just out of curiosity, how large is the 'dewar'?

Removing the boil off from a tank and reliquifying it is typically the most expensive option you can choose. There is no simple way of doing this economically (key word: economically). Companies are looking at this type of problem continuously. Everyone at one time or another that ever uses a cryogenic liquid looks at the same issue. The end result is fairly obvious once you've done an economic study, there is no way to reliquify it without spending more than you save.

To minimize waste, the supply should always be in the proper form. If a cryogenic tank is used, the boil off should go directly to the process that consumes the gas. If there is excess boil off, the tank is too large and the solution is to get a smaller one.

Getting a smaller tank has trade offs as well. The smaller the tank, the higher the cost is likely to be from your supplier because of the larger number of deliveries needed.

Getting supplied from liquid cylinders (small, portable, vacuum insulated cans about 100 to 500 Liters in size) is an option when a stationary tank is too large. Generally, stationary tanks don't get much smaller than 1500 gallons, though I've seen them down to a few hundred gallons - they're just not economically viable due to delivery issues.

However, if liquid cylinders are still too much, then the only smaller means of transporting and storing the gas is to use banks of high pressure cylinders. They can come on a pallat with various numbers of cylinders attached, generally a dozen. They're moved around with a fork lift.

Sorry I couldn't be of more help, but reliquifying Argon (or any cryogen, even helium) is rarely an economical process.

 

[mminford]

Thanks iainuts, I appreciate the help. I thought this would be the case, but I just wanted to be sure since I am new to the field. If you have any valuable information that would help me in my career in cryogenics (websites, books, etc.), I would be greatful of it. If not, I thank you for all of your help.

 

[weeeds]

Is an option to capture the vapour in a secondary vessel? You can draw gas from it until it is empty and then switch over to the bulk tank.