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In Our Hydro Cracker we face the problem in Naphtha circuit. The product naphtha fails due to colouring. But the other products are passing all the required test and parameters. Has anyone faced such problem; if so what could be the reason for naphtha product alone getting coloured?
 
Answers
16/05/2010 A: Syamantak Dhar, Indian Oil corporation Limited, syamantak.dhar@aol.in
All the answers given prior to me are certain possibilities that might occur and cause the above phenomenon. But you can also try to increase the Flow of the Gas-Oil and Kerosene Pump around (keeping the same Heat Duty) and also directionally increase the Top Reflux flow to the Main Fractionator. If your light naphtha is only failing in the colour try to have huge reflux flow (Typically above 20 M3/hr) to the Naphtha Stripper.
03/04/2010 A: Ralph Ragsdale, Ragsdale Refining Courses, ralph.ragsdale@att.net
If not near EOR, there could be channeling through the beds, creating hot spots that cause off-color material.
03/04/2010 A: Ralph Ragsdale, Ragsdale Refining Courses, ralph.ragsdale@att.net
My guess is polynuclear aromatics building up in the system. Does your unit have the special filter on the liquid recycle stream, or do you use a drag stream? The color problem would be noticed in the naphtha first, in my experience.
Alternatively, you are at the EOR, i.e., maximum WABT, and need to shut down.
03/04/2010 A: keith bowers, B and B Consulting, kebowers47@gmail.com
If there is a heat exchanger (naphtha/feed) for instance, a tiny leak will cause the problem.
Otherwise, the hydrogenation activity of the catalyst is not sufficient for the naphtha. Contact your catalyst supplier and process Licensor for assistance.