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[APGR]

Hi,

 

I am looking at the dew pointing of natural gas both water and hydrocarbon dew point. From what I understand, the method of mechanical/expansion refrigeration and adsorption can simultaneously meet water and hydrocarbon dew point, but the method of absorption cannot. It will need a separate water dehydration facility (using TEG) and then a condensate removal facility (Absorption Oil). Is this correct/the general method used in industry for an absorption system? From my research, this method is not as prevalent as refrigeration/adsorption. Are there any other reasons for this except the high cost of recovering the TEG and absorption oil?

 

 

[Art Montemayor]

APGR:

 

What is “dew pointing”?  Are you converting a noun into a verb?

 

You should always be explicit is explaining what the topic is all about.  Are you referring to a natural gas treatment unit where the amount of heavier hydrocarbons in the natural gas is being regulated as well as the amount of water content?  If so, you should obtain a copy of the GPSA Engineering Databook - hard copy or electronic version.  Therein, you will find explanations and illustrations on natural gas treatment and controlling the hydrocarbon and water dew points of the product gas.  For more information, go to https://gpsa.gpaglob...atives/databook.

 

The adjective “simultaneous” means occurring, existing, or operating at the same time; concurrent.  This is not what occurs when you remove hydrocarbons and water from a natural gas in order to “condition” it to product specifications.  The step of removing heavy hydrocarbons is one step while the dehydration is another.  The steps are not done simultaneously but sequentially.

 

If you are dehydrating natural gas with pipeline specifications, this will normally require a water content of 7 lb/MMScf of natural gas as a maximum.  To obtain this specification you can use either TEG absorption, adsorption, or calcium chloride as a desiccant - depending on your needs and the size and condition of the gas flow.

 

You should normally remove the hydrocarbons first to avoid contamination of the subsequent TEG absorbent used for water removal.  I don’t know where you “researched” that refrigeration/adsorption are more prevalent methods for conditioning natural gas.  Please explain.

 

Thank you for making me go to the GPSA webpage after some years, in order to get the URL for you.  That allowed me to find that the GPSA has been very busy and has recently upgraded their site with some excellent Excel workbooks that complement the Databook with calculation spreadsheets.  I highly recommend that you and all students download these rich workbooks and work on the example calculations and contained materials.  I also recommend that you purchase a copy of the Databook.  You will never regret it if you become a professional chemical engineer.