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In a Hydrocracking reactor, the degree of cracking is maximum in which bed? In the first bed, the extent of reaction (exotherm) is higher but lower bed (third bed) temperature is highest. Also since the most complex molecules like disubstituted DBT will be reacted in the lowest bed, will cracking be maximum there?
 
Answers
09/11/2020 A: Jake Gotham, InSite Technical Services, jake.gotham@insitetechnical.com
Your observation that the exotherm is highest in the first bed suggests to me that you are describing a single stage unit or the first stage of a two-stage unit. In either of these cases, the exotherm in the first bed is generated by hydrotreating reactions. If you look at the catalyst loading diagram you will see that the first bed does not have any cracking catalyst in it; the same is probably true of the second bed. If you look for the bed with cracking catalyst with the highest exotherm, you’ve probably found the bed doing most of the cracking.