4 replies to this topic

[VikingUK]

Does anyone have any advice on calculating how much MEG I should inject in a gas flowline to inhibit hydrate formation ?

I've been using X = dM/Ki+dM
where
d = °C depression of hydrate point (we use an extra safety margin of 5 °C on this value so d = Hydrate Formation Temp. - Min. Op. Temp. + 5

x = weight percent of inhibitor in the liquid water phase

M = mol weight of inhibitor

Ki = constant ( 2220 for glycol)

Taken from Campbell’s “Gas Conditioning and Processing – Volume 1, The Basic Principles

But I'm not sure if I should be allowing for how water wet the gas is (about 350ppmv)as there is no water phase in a gas line

[shan]

Does anyone have any advice on calculating how much MEG I should inject in a gas flowline to inhibit hydrate formation ?

I've been using X = dM/Ki+dM
where
d = °C depression of hydrate point (we use an extra safety margin of 5 °C on this value so d = Hydrate Formation Temp. - Min. Op. Temp. + 5

x = weight percent of inhibitor in the liquid water phase

M = mol weight of inhibitor

Ki = constant ( 2220 for glycol)

Taken from Campbell’s “Gas Conditioning and Processing – Volume 1, The Basic Principles

But I'm not sure if I should be allowing for how water wet the gas is (about 350ppmv)as there is no water phase in a gas line

Sure, it is a fancy formula. When we need chemical inject rate information, we always relay on the chemical provider's advice. The methanol/water ratio is between 1:3 and 1:6 depending on gas pressure to prevent hydrate formation. If LDHI is used, the ratio is something like 1/42.

[daryon]

But I'm not sure if I should be allowing for how water wet the gas is (about 350ppmv)as there is no water phase in a gas line

Hi Viking

No i don't think you need to allow for the gas water content. THe MEG solution that is injected as hydrate inhibitor is likely be 50 to 70 % MEG and the rest water. This is how you determine your value for X.

If you have access to HYSYS you could try cross checking the results of your hand calculations against the HYSYS hydrate formation utility. The Utility will predict the hydrate formation conditions for you gas stream. You can then add a mixer and introduce a stream of say 60% MEG 40% water (by weight)to your gas stream. You then enable the hydrate inhibitor calculation within the utility and adjust the flowrate of your MEG solution to see what the effect on the hydrate formation temperature is.

[rraffiel]

Does anyone have any advice on calculating how much MEG I should inject in a gas flowline to inhibit hydrate formation ?

I've been using X = dM/Ki+dM
where
d = °C depression of hydrate point (we use an extra safety margin of 5 °C on this value so d = Hydrate Formation Temp. - Min. Op. Temp. + 5

x = weight percent of inhibitor in the liquid water phase

M = mol weight of inhibitor

Ki = constant ( 2220 for glycol)

Taken from Campbell’s “Gas Conditioning and Processing – Volume 1, The Basic Principles

But I'm not sure if I should be allowing for how water wet the gas is (about 350ppmv)as there is no water phase in a gas line

[rraffiel]

Hi,

I'm getting used to this new forum. Try the following:

http://www.ogj.com/i...ction-rate.html