VDU ejector off gas

[Milutin]

Off gas from the refinery vacuum distillation unit is routed to fired heater. Off gas is rich in H2S and results with increased SO2 emmision from VDU heater. What are the cost effective solution available to remove H2S from this stream?

Regards,

 

[dcasto]

depends on strean size and H2S concentration. Plus stream conditions of temp, press, and other constituants.

 

[Milutin]

Thank you for your replay dcasto. Stream description is:
Pressure:0.05bara
Temperature:50degC
Quantity:1000kg/hr
Composition:
H2S 30 mol%
O2 0.1mol%
N2 1.7mol%
CO 4.4mol%
CO2 0.4mol%
H2 2.4mol%

Rest is light hydrocarbons. Suppose it is necessary to increase stream pressure and send it amine unit, which technologies are available?

Regards,

 

[dcasto]

looking at the composition, by brain says, the least amount of handling is what will set the technology. The fewest steps and processes the better.

With that, you will need to compress, if you turely have .05 bar absolute, even .05 bar gauge is tough enough.

Physical solvents require the most pressure, so they would be my last choice.

If you can have brown sulphur, I'd look at direct conversion of the stream in a iron chelate process lo-cat is typical.

If sulphur specs are tight, then a primary amine would be used.

Shell has a biological based system you could look into.

 

[CJKruger]

Milutin, some companies put it to a flare header. The Flare Gas Recovery system is then used to send it to an amine unit. Several risk though (like air into your flare system).

 

[EmmanuelTop]

Oxygen content is rather low. I can't foresee any associated risks.

http://antwrp.gsfc.nasa.gov/apod/astropix.html

 

[dcasto]

If you have a primary amine, the O2 will react and make a salt and you'll have to reclaim the amine much harder.

 

[EmmanuelTop]

I agree for the amine issue - Oxygen is definitely a concern. But for the off-gas compression I see no risk as we are well outside the LEL-UEL range.

http://antwrp.gsfc.nasa.gov/apod/astropix.html