7 replies to this topic

[Graduate process ENG]

On TEG we do have flash gas from flash drum ,my question is can I re-used this gas as stripping gas instead to flare it .

[sri]

On TEG we do have flash gas from flash drum ,my question is can I re-used this gas as stripping gas instead to flare it .

Dehydrated gas at low temeratures, if used as stripping gas, has great ability to absorb moisure from glycol. It is not advisable to use flash gas from flash drum as it will affect your lean glycol concentration and hence dew point of dehydrated gas.

[Zauberberg]

Flash gas is saturated with water (it leaves the vessel as such), and in these conditions cannot be used for water removal from lean TEG.
I am speaking about the most common stripping gas applications where targeted TEG purity is 99.9% or more, and I believe that was your question about. Introducing wet gas (which is in equilibrium with water) as stripping medium can only make things worse.

[Graduate process ENG]

On TEG we do have flash gas from flash drum ,my question is can I re-used this gas as stripping gas instead to flare it .

Dehydrated gas at low temeratures, if used as stripping gas, has great ability to absorb moisure from glycol. It is not advisable to use flash gas from flash drum as it will affect your lean glycol concentration and hence dew point of dehydrated gas.

THanks Sri for your clearness

[Graduate process ENG]

Flash gas is saturated with water (it leaves the vessel as such), and in these conditions cannot be used for water removal from lean TEG.
I am speaking about the most common stripping gas applications where targeted TEG purity is 99.9% or more, and I believe that was your question about. Introducing wet gas (which is in equilibrium with water) as stripping medium can only make things worse.

Zauberberg,

I don't know how I missed this , thanks for replay .

[Neelakantan]

Flash gas is saturated with water (it leaves the vessel as such), and in these conditions cannot be used for water removal from lean TEG.
I am speaking about the most common stripping gas applications where targeted TEG purity is 99.9% or more, and I believe that was your question about. Introducing wet gas (which is in equilibrium with water) as stripping medium can only make things worse.

Zauberberg,

I don't know how I missed this , thanks for replay .

hi Z,

as a general concept where regeneration is meant to remove water, adding water in the saturated gas in the form of stripping gas may look as a bad idea.
however, remembering that the overall heat load of the regeneration system could be about vaporising say 200 kg/hr of water (a rough number) adding a strip gas containing 2 kg of water shall not have an adverse impact,

also the other components are still there C1 to C3 which are essentially effective in reducing the partial pressure.

yes i understand that a drygas / n2 will be more effective. but if the flash gases are going as waste, better to use it.

regards
neelakantan

[JoeWong]

Why not simulate and check the result ?

Check out how much flashed gas you need and check if the flashed gas is sufficient.

[Neelakantan]

hi
yeah; did the same (rather i have done this in design and set an unit operating in indonesia for caltex). i believe it is a practicable solution, if you have more flash gas especially for these electric reboillers.

if you have fuelgas from the dried gas then that can be used.

the only thing i did for an fpso top units was to add a secondary packed "boot" so that the vent gas is also somewhat dried

regards
neelakantan