Dehydration with Sweetening 1

[RRE]

Was challenged with a design to remove 0.1% of CO2 (3.1 mol % to meet a spec of 3.0%) by using an amine (such as DEA) mixed with TEG. As anyone added amine to their glycol (TEG) to sweetened? I am aware that amine is added for glycol pH control, but I've not heard adding amine to the glycol to both dehydrate and sweetened.

 

[abdel27]

You are right... Do the steps separately . Dehydrate then sweet the gas !

 

[Montemayor]

I believe the sweetening step, if required, should be the first step - followed by the dehydration step, especially if the sweetening is done using an aqueous amine solution. DEA and amine are mentioned. What is left out is that any amine solution is an aqueous medium and, as such, imparts water vapor pressure to the exit product gas out of the top of the absorber. This product gas, of course is saturated with the liquid with which it is in intimate contact at the top of the absorber - which is water and amine. This is why it does not make good sense to dehydrate before submitting the same gas to an aqueous solution absorption system. One would have to dehydrate again after the absorption because of the subsequent water pick-up.



Art Montemayor
Spring, TX

 

[RalphHicks]

I agree with Montemayor and abdel27. To minimze costs, particularly with only 0.1% CO2 being removed, you may wish to consider an inexpensive amine system, such as Natco's Glymine [

http://www.natcogroup.com/Content.asp?t=ProductPage&ProductID=28

]. You can use a slip stream (bypass much of the gas) and then dehydrate with glycol.