Gas Hydrates Prediction

[ChemE2912]

Hi there!

I am working on a simulation for a gas conditioning system. I am confronting the following problem:

When I expand the gas from 1330 psig down to the desired pressure in order to achieve the required properties (i.e., %methane), the simulator predicts gas hydrates in the two-phase stream that enters to the two-phase separator.

I have the following doubt: Can gas hydrates exist in two phase streams?

Moreover, I am feeding methanol to dissolve the hydrate. The gas stream that is flashed in the separator does not have hydrates, but in order for the hydrate to dissappear in the two-phase stream entering the separator, I have to supply too much.

In addition to that, there are three models to predict hydrates: symmetric, assymmetric and vapor only. Which one would be the best to predict in my model?

What would be a good Internet/book source to deal with this problem?

Any advise is well appreciated.

ChemE2912

 

[MortenA]

Hydrate can exist in three phase environment but requires free water (at least in practise) to form.

There should be many sources avaiable. Try a good serach engine like google.

Best regards

Morten

 

[Alph]

Natural Gas Hydrates - A Guide for Engineers [2003]
John Carroll - Gulf Professional Publishing
ISBN 0-7506-7569-1

Hydrates of Hydrocarbons - Yuri F. Makogon [1997]
ISBN 0-87817-718-7
Penwell Books

Formation of hydrates requires the following 3 conditions :
1. The right combination of pressure & temperature
2. Hydrate formers (Methane, Ethane & CO2(
3. Sufficient ammount of water (not too much or too little)

Al

 

[tkdhwjd]

Just a thought....

If you have water and methane in vapor phase as the stream flashes, then at right temperature and pressure (depends on the specific gravity of the vapor stream) would result in the formation of water crystalline structure. Methane would immediately occupy void space in the crystalline and stabilize the structure, thereby forming hydrates. So I believe it is possible to form hydrates in a 2-phase flow stream.