Glycol injection for hydrate prevention

[VikingUK]

I use MEG injection as a hydrate inhibitor when my gas pipeline pressures/temps get inside the hydrate formation envelope.
Does anyone have any ideas on injection rates ?
I'm basically just guessing and probably way over injecting and wasting glycol.
A calculation or table based on gas composition/temp/press/flow would be much appreciated.

 

[tickle]

GPSA has a method for calculating.

The calc should allow for initial glycol concentration, glycol lost to the vapour phase and glycol lost to the condensate phase.

 

[VikingUK]

I am not a member of GPSA

 

[ayoyo]

I think tickle is suggesting you to get a copy of GPSA book.
Inside this book, you will find method to estimate MEG requirement.
You calculate the minimum inhibitor concentration required in your water phase based on Hammerschmidt's equation, then you size your dosing rate based on your production rate.

 

[VikingUK]

Unfortunately I have to go through company purchase procedure and it takes ages.
I know of Hammerschmidts equation but I really don't have much idea of how wet my gas is. All I can go by is comparing what is knocked out in the separator against total volume flow

 

[tickle]

I would think that your company would have GPSA in its library and if not then one of your colleagues may have it.

The water flow would be based on the liquid flows into the separator. Assume that the gas is fully saturated with water.

 

[maddocks]

Easiest way is to assume saturation on your gas - thats the safest and smartest. Build a quick simulation and run it and see.

 

[dcasto]

how is over injecting wasteing glycol, don't tell me, you don't recover it on the other end and recycle it.

 

[MortenA]

Maybe you should get a consultant if you dont have inhouse knowledge? If you loose a pipeline to a hydrateplug then its a serious ting... (stateing the obvious)

Best regards

Morten

 

[dcasto]

Look at Chapter 20 Example 20:10 of the NGPSA databook.

For 100 MMSCFD at 1200 psia and 100 F with a hydrate temperature of 65 F and an ultimate temperature of 40F, you'll need 4350 pounds per day of 80% by weight EG.


Get the book and see the details, but this should give you a clue of where you should be.

 

[BigInch]

Why not buy the book and submit it as an expense item to your company. (Clear it with the boss first.)

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