Gas Dehydration

[kloroform]

hi All,

i want to know how do we define the best way to dehydrate gas from 20 lb/mmscfd to 4 lbb/mmscfd, by using Glycol Dehydration Unit or Molecular sieve ? as far as i know molecular sieve is more expensive than using glycol, but what is the limitation of using molecular sieve ? dew point or what ?

thanks

 

[zdas04]

You can get to whatever dew point you want to with a mole sieve (unlike a deliquescent dryer), the reason that so many people prefer glycol is that it is so much easier to regenerate the glycol efficiently. Rejecting the water out of a mole sieve is difficult and expensive.

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

 

[EmmanuelTop]

Unless you need 0.1 ppm of water in the treated gas, you won't go for Mol Sieve.


Dejan IVANOVIC
Process Engineer, MSChE

 

[zdas04]

Dejan,
I can get to 0.1 ppm water in gas with a mol sieve. It would be kind of big (maybe visible from space), but it is physically possible. I'd just hate to have to get the water back out of it.

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

 

[EmmanuelTop]

Hi Dave,

That is a common spec in LNG plants. And the regeneration is energy intensive, yes. So unless you really need 0.1 ppm there is no point going for it, like I mentioned in my first post.

Dejan IVANOVIC
Process Engineer, MSChE

 

[kloroform]

dear all, thanks for your respond

i want to ask basic questions. first what makes glycol can absorp vapor water in gas ? and why the liquid glycol is not entrained to gas output ? (we want to remove water vapor but we use liquid ?)

 

[kloroform]

i mean, why there is no glycol carried over to gas stream ?

 

[zdas04]

Sorry kloroform, you've crossed a line here. The mass transport of vapor into glycol is just too basic, too second year, too fundamental to believe that you really are any sort of engineer, let alone a graduate chemical engineer. I'm thinking sophomore at a minor university. We really can't do your homework for you.

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