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We have semi regeneration plateforming unit and currently it the third cycle. Catalyst is platinium/Rhenium.We are continuesly loosing Reactot Delta T. At SOR it was 129 deg C.while currently after 19 moths it is 90 deg C. MCH and CIS di methyl cyclo hexane in feed is 10.6 vol% while in reformate both are 1.2 vol%.Stab. ovhd gasses production is also very high. Hydrogen purity in previous cycles were above 90 while currently it is in between 87~88%. we have also experienced crude blend change in the current cycle. Naphthenes are currently 32 wt % while previously it was near to 35 wt %. such decrease in delta T was not experienced in previous two cycles. What are the possible causes?and what are the remedial actions to save the catalyst.
 
Answers
15/12/2010 A: Ralph Ragsdale, Ragsdale Refining Courses, ralph.ragsdale@att.net
(1) The naphthenes conversion appears high. Is that normal for your unit? (2) With "very high" light ends and low delta T, overcracking is indicated. Either high temperature or excessive chloride on catalyst could be the cause. Try reducing chloride injection first.