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Finding Hydrotreater H2 partial pressures!!???

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SchemeUK

Chemical
Nov 20, 2002
1
GB
Hi,

I am currently in initial stages of Hydrofining design project at Nottingham University (UK).

I'm having great difficulty in finding a reliable source for accurate partial pressures of H2 in the reactor.

My feed consists of straight run GO with a small amount of LCO and fresh hydrogen to produce 50ppm sulphur diesel. I know it depends on the degree of cracked component in the feed but can't find anything more specific than 20-40bar.

I would appreciate any comments and or advice on the subject.

Many Thanks
 
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Well, I'm not sure about this being what you needed but I'm currently working on the OBL section of a hydrotreater revamp project to meet the upcoming US 15 ppm diesel sulfur limits.

The diesel hydrotreater I'm involved with runs about 55 bar now so it's in your range. Current H2 comes off their platformer and is just over 80% pure. To meet the 15 ppm sulfur requirement, they are (along with other site modifications) installing a PSA unit to essentially produce 100% H2 which will supply the hydrotreater.

The offgas from the diesel hydrotreater with pure H2 supplied is expected to be about 93% H2 with the bulk of the remainder being H2S and methane, less than 1% ethane and the rest minor components.

The key thing here is what is your H2 makeup gas concentration? I would take your outlet gas as perhaps 80% to 90% of this concentration and use that to estimate your partial pressures. Alternatively (I don't know how much data you have for makeup and recycle H2), you should be able to do a mass balance around the hydrotreater using how much H2S you will produce and thus how much H2 will remain and thus the partial pressure.

Have you contacted UOP to see if they could give you some global parameters to work with as their is their area of expertise?
 
TD2K has rightly pointed out to you in the direction of UOP as they are leaders in hydrofining technology.to answer your query, the partial pressure of h2 will be the purity of hydrogen multiplied by the system or loop pressure.
If your makeup gas is from a hyudrogen unit then in all possibility the pirity will be 99.9% or more and ur partial presure will depend on purity of circulating " recycle gas" which in your case will contain H2S
 
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