3 replies to this topic

[Farnaz1989]

Hi everyone,

I have a question regarding sweetening of C₅⁺ stream in a gas treating plant.

Here is the scenario:

The c₅⁺ stream with total mercaptan of 6000ppm is going to be sweet. the licensor has proposed to utilize a caustic wash unit to treat the stream; on the other hand, the owner's suggested to harness an HDS unit to remove higher amount of sulfur but they are confused whether it's necessary to use both HDS and Caustic units at the same time?

Please help me answer the mentioned question.

[Max3008]

I think in case you need to seperate S in compound to prepare the next process you need HDS and caustic. HDS to convert S in compound to H2S and at that time, you need caustic to seperate H2S out of offgas.

In case you just wanna eliminate the mercaptan, you could use Merox process

[rdcrags]

If HDS is used, further treating is not needed.

[colt16]

What do you mean by sweetening? 

 

If by sweetening you mean remove the sulfur, take note that the MEROX process does not eliminate sulfur. It merely oxidizes mercaptan species to disulfides. The sulfur content remains the same. 

 

If by sweetening you means simply removing mercaptan, and allow it to stay as disulfides, then the caustic process is good enough. 

 

A hydrogen desulphurizer is much more expensive than a mercaptan conversion to disulfide process.