Cost comparison of salt dryer vs molecular sieve
Cost comparison of salt dryer vs molecular sieve
(OP)
I have been asked to come up with a quick comparison of CaCl2 dryers and molecular sieves for drying of 200 t/h LPG. I think I have a good idea of the technical comparison and the operational considerations based on thread135-124876: CaCl2 Dehydration of LPG, but I have little experience with the capital cost comparison.
I am looking for a rough comparison, ie, 4x the cost for mol sieve vs others. I estimate the salt dryer option will cost about $700-800K.
Any input from the forum will help.
MT
I am looking for a rough comparison, ie, 4x the cost for mol sieve vs others. I estimate the salt dryer option will cost about $700-800K.
Any input from the forum will help.
MT





RE: Cost comparison of salt dryer vs molecular sieve
- Salt dryers at their very very best can get you a 20°F dewpoint depression. Mole Sieve can get you what every dew point you design for.
- Salt dryers can remove about 3 lbm of water for every lbm of salt that is consumed. Mole Sieves are not consumed.
- Salt dryer media is consumed. Mole Sieve media is regenerated. Think about this one, if you have 1 MMSCF/day of 600 lbm/MMSCF gas then you have to drain off 800 lbm of brine (call it 100 gallons) and add 200 lbm of salt EVERY SINGLE DAY. If you are talking more than a couple of MSCF/day the operators will hate you.
Cost is never the determining factor in this kind of decision. If it is big enough to consider a Mole Sieve (and it's attendant regeneration heat source) then there is no way that you would ever consider doing the job with salt.David Simpson, PE
MuleShoe Engineering
In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. —Galileo Galilei, Italian Physicist
RE: Cost comparison of salt dryer vs molecular sieve
I'm not a fan of salt driers and one of my primary concerns is whether or not they'll even work and produce a product that meets a standard C3 freeze valve test. However, many references indicate they are used quite often for drying liquid C3.
Thanks in advance for any information you can share.