10 replies to this topic

[Mehdi Alizad]

Hi everybody,
I have a question about gas sweetening and merox processes,

Gas sweetening is a process which acid gases (H2S & CO2) are removed by solvents, mostly amines.

Merox is a process which mercaptan and sulfur contaminants (RHS, COS,...) are removed from natural gas by using NaOH, O2 and catalyst.

Both of above processes are done seperately

Q: Is there anyway, any process, any solvent or any additive which enables both of those processes merged and done together in just one process, for example adding an additive to amine which enables amine to absorb RSH, COS beside CO2 & H2S

This question is related to my master science thesis

Thanx,

[ankur2061]

Mehdi,

Are you stuck with amines? Because there are new absorbents & solvents which can simultaneously remove H2S, CO2, COS and R-SH.

There is plenty of information on the internet about new chemicals being employed for removal of the above mentioned compound simultaneously. Some links are provided below:

http://www.ics.clariant.com/C12575E4001FB2B8/vwLookupDownloads/AbsorptionFluidsForGasTreatment_Newsroom_Brochures_The_Selexol_Process_Acid_Gas_Removal_AGR.pdf/$FILE/AbsorptionFluidsForGasTreatment_Newsroom_Brochures_The_Selexol_Process_Acid_Gas_Removal_AGR.pdf

http://www.bre.com/p...val REVISED.pdf

http://www.scribd.co...P#outer_page_30

Hoe this helps.

Regards,
Ankur.

[Mehdi Alizad]

I know about all these processes u mentioned

but there is an important point: all these solvents (processes) are physical (except DIPA in sulfinol process) which need higher operating pressure & circulating rate to achieve sweet gas standards.

additionally all of them have expensive licenses.

and as u know amine process (MDEA) is most used process in the world.

So removing H2S, CO2, COS and R-SH simultaneously in amine process can be beneficially.

[naeemullah]

if you are talking about LPG,NAPHTHA then, using NAOH will solve the problem (LPG MEROX)

[RockDock]

Yes, a caustic solution is your only other choice. It will first remove H2S then the thiols.

[Art Montemayor]

Mehdi:

To my knowledge, there is no one process that simultaneously removes H2S, CO2, mercaptans, COS, and other organic sulfur compounds. At least, not recognized in field performance and dependability. There may be a lot of claims out there, but the proof is always in the pudding: how many years of field performance can be accurately claimed in operation?

The amines - specifically those like MDEA - continue to be relied upon for efficient H2S removal and the Claus process applied downstream for the final sulfur removal in the elemental stage.

I seriously doubt if you can simply combine all your sulfur compound problems into one process for ultimate removal of the insidioud sulfur contaminants in a field hydrocarbon stream.

[akhavans]

Hello all,

 

We are performing a design for mercaptan removal from a liquid and gas stream. Both streams have been pretreated to remove H2S and CO2 - the concentration of these two are negligible.

The gas stream is primarily C1 - C3 (79wt%), but 4wt% is C5+.

The liquid stream is 23wt% C3, 32wt% C4s, 22 wt% C5s, and 13 wt% C6, and 7wt% C7+

 

Based on the research we've performed, we've come to the following conclusions:

1) chemical absorption (MEA, MDEA, DGA, etc) are ineffective for mercaptan removal

2) adsorption (molecular sieve): strong option, but heavy HC loss will occur (particularily important for liquid stream). A physical separation unit (ex Selexol) will likely be required in order to separate rich regenerated fluid into HCs and mercaptans

3) caustic treating (ex MEROX): strong option, but disulhpide handling issues will be present due to oxidization reaction.

4) physical separation alone (ex selexol)

 

If any of you can provide any input and/or recommendations on the design, it would be greatly appreciated.

 

Thanks!

 

[fallah]

3) caustic treating (ex MEROX): strong option, but disulhpide handling issues will be present due to oxidization reaction.

 

Hi,

 

Disulfate oil can be separated in a three phase; Spent Air (Gas Phase), Disulfide Oil (Organic Liquid Phase), Lean Caustic Solution (Aqueous Liquid Phase); separator. Then will pass through a sand filter in order to trap any lean caustic carry over...and finally is transferred to storage area...

 

What is the issue you mentioned for disulfide oil?

[akhavans]

 

3) caustic treating (ex MEROX): strong option, but disulhpide handling issues will be present due to oxidization reaction.

 

Hi,

 

Disulfate oil can be separated in a three phase; Spent Air (Gas Phase), Disulfide Oil (Organic Liquid Phase), Lean Caustic Solution (Aqueous Liquid Phase); separator. Then will pass through a sand filter in order to trap any lean caustic carry over...and finally is transferred to storage area...

 

What is the issue you mentioned for disulfide oil?

 

Thank you for your response. What are DSOs used for after storage? The research we've performed suggests that DSOs can be sent to hydrotreater, fractionator (and components sold), or fuel system. We do not want to send them to fuel since SO2 emissions will increase.

 

Thanks again for your response.

 

Our facility may not have storage capability for DSOs. Based on the research we've performed, the DSOs can be separated and sold, hydrotreated, or sent to fuel system. Obviously sending DSOs to fuel system will result in increased SO2 emissions. B

[fallah]

 

What are DSOs used for after storage? The research we've performed suggests that DSOs can be sent to hydrotreater, fractionator (and components sold), or fuel system. We do not want to send them to fuel since SO2 emissions will increase.

 

 

Hi,

 

DSO can be sent to burn pit or incinerator to be burnt. As far as i know it can be sold for using in some industries as raw material...

[P.K.Rao]

Since you are researching, I have a process which removes mercaptans from liquid streams. The process is experimented only on a bench scale. If you have any interest, please contact me.

I also know a chemical which can be possibly used as a mercaptan scavenger at low concentrations. Try quinone. which will combine with mercaptans and form an addition compound.

P.K.Rao

pkrao2012@yahoo.com