Switchable Hydrocracking Reactors for High Asphaltene Feedstocks
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Solution Overview
Problem
Catalytic hydrocracking processes for heavy hydrocarbon feedstocks with high asphaltenes and metal content face rapid catalyst deactivation and coking, leading to shortened operating durations and increased costs due to the inhibition of catalytic activity and deposition of coke and metal sulphides, which necessitates frequent replacement of catalytic beds.
Innovation Solution
A process involving a fixed-bed hydrocracking catalyst system with a hydrodemetallation section followed by deep hydrorefining and hydrocracking, using switchable and by-passable reaction zones with specific catalysts and operating conditions to extend run duration and maintain high performance levels, including the use of macroporous catalysts with high demetallation rates and resistance to coking, and a catalytic system with a 'grading' approach for hydrodemetallation and hydrorefining zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional fixed-bed hydrocracking processes are used with feedstocks containing high asphaltenes and metals, then the process can handle heavy hydrocarbon fractions, but the catalyst rapidly becomes loaded with metals and deactivated, requiring frequent replacement
Solution Approach 1:
The hydrocracking process is divided into multiple catalytic beds with different functions: guard beds for hydrodemetallation, hydrorefining beds for deep refining, and hydrocracking beds for conversion. This segmentation allows each catalyst type to specialize in removing specific impurities, preventing rapid deactivation and extending run duration while handling high asphaltenes content feedstocks
2Reliability
If temperature is increased to compensate for catalyst deactivation, then demetallation and deasphaltenation performance is maintained, but coke formation increases and feedstock losses increase
Solution Approach 1:
Hydrodemetallation and hydrorefining are performed in advance in dedicated catalytic beds before the feedstock enters the hydrocracking beds. This preliminary removal of metals and asphaltenes prevents catalyst deactivation, allowing the hydrocracking process to operate at optimal temperatures without excessive coke formation and feedstock losses
3Reliability
If frequent catalyst replacement is performed to maintain performance, then high demetallation and hydrorefining performance is maintained, but operating duration is reduced and operating factor decreases
Solution Approach 1:
The use of multiple specialized catalytic beds enables extended operating durations by allowing sequential treatment of different impurity types, reducing the frequency of catalyst replacement while maintaining high performance levels throughout the run
Solution Approach 2:
The multi-bed configuration allows spent catalysts to be selectively replaced based on their specific function and depletion rate, optimizing the replacement schedule to maintain performance while maximizing operating duration between replacements
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The process significantly extends the operating run duration while maintaining high hydrorefining and hydrocracking performance, reducing the need for frequent catalyst replacement and minimizing losses, thereby improving the economic viability and stability of the hydrocracking unit.
Implementation Method 1
The feedstock is subjected to a hydrodemetallation treatment... in at least 2 switchable reaction zones each containing at least one hydrodemetallation catalyst
Implementation Method 2
hydrodemetallation treatment... with a hydrogen/hydrocarbons ratio of between 200 Nm3/m3 and 2,000 Nm3/m3
Implementation Method 3
at least a part of the effluent... is hydrorefined in a hydrorefining section containing at least one hydrotreatment catalyst in order to lower the organic nitrogen content to below 20 ppm by weight
Implementation Method 4
deep hydrorefining (HDR) of the feedstock, and in particular hydrodenitrification (HDN) and hydrodesulphurisation (HDS)
Implementation Method 5
then at least a part of the effluent... is hydrocracked in a hydrocracking section containing at least one fixed-bed hydrocracking catalyst
Implementation Method 6
hydrocracking the feedstock in the last catalytic bed or beds... The effluents drawn off after the last catalytic bed are then fractionated to produce various petroleum cuts
Data Source
AI summary
The invention relates to a process for hydrocracking hydrocarbon feedstocks having 200 ppm by weight to 2% by weight of asphaltenes and/or more than 10 ppm by weight of metals, comprising a hydrodemetallation treatment in at least 2 switchable reaction zones, containing hydrodemetallation catalyst and optionally hydrodenitrification catalyst, then a hydrorefining treatment to lower the organic nitrogen content, followed by a fixed-bed hydrocracking treatment and a distillation step.