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Question No.:  5899 Category :  Refining
Date Posted:  5/14/2017
Subject: LHSV in hydrocracker
Could someone please tell what is the exact LHSV of single stage 5 bed hydrocracker reactor if the catalyst is new?
Submitted by :
Company Name:

Jamnagar, Gujarat, India


Number of responses : 3
Response 5899-1
Date : 5/16/2017

If the unit is being designed, the LHSV is part of an optimization study where several inter-related variables are part of the optimization. If the unit is existing, a similar optimization calculation may be made based on the expected feed composition and desired product distribution and specifications. With a fixed catalyst inventory, a study may be made with varying feed rates and reactor inlet temperatures to determine the maximum annual revenue. Because run lengths will vary between study cases, the effect of downtimes on the revenue must be a variable in the calculation. To account for this, use a 5 or 10 year period for the study basis.

Name - Ralph Ragsdale
CompanyName - Ragsdale Refining Courses
Location - Houston, TX, USA
Email -

Response 5899-2
Date : 5/17/2017

A single stage hydrocracker means one continuous reaction zone in 5 bed Rx. So, your LHSV will be the hourly volume of the combined feed over the catalyst volume (V/V/h or 1/h).

Catalyst vendors convert the specified volume into pounds of catalyst sufficient to dense load the given Rx volume. This volume consider as your new catalyst volume.

LHSV is designed in combination and interaction with other parameters to produce desired reactions rate, selectivity and conversion. Increased LHSV reduce residence/contact feed with catalyst and demands higher T, H2 flow, that increase coking, deactivation rate. So, proper optimization is needed to set key operational parameters over catalyst run length.

Name - Milorad Popovic
CompanyName - Process Eng.
Location - Montreal, QC, Canada
Email -

Response 5899-3
Date : 8/5/2017

Hydrocracker (HYC) reactors contain number of catalysts bed for different purposes. Top bed may be a grading bed for delta P control as well as distribution. However, very good distributors are also used for proper liquid gas distribution radially and to prevent channeling. Other beds are HDM, HDS, HDN and HYC beds. Proper function of each bed is necessary to make effective desired conversion. Depending on design basis LHSV takes consideration of the total volume of catalysts and defined as feed throughput per unit catalyst volume.

Name - Virendra Kapoor
CompanyName - Petroleum Refining Consultants
Location - Dehradun, Uttarakhand, India
Email -


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