Integrated Two-Stage Hydrocracking Reactor Design
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Solution Overview
Problem
Two-stage hydrocracking processes are costly due to the need for additional equipment, but they offer a cleaner reaction environment that allows for the use of more sensitive catalysts, necessitating a solution that minimizes equipment and operational costs while maintaining the advantages of a two-stage reactor.
Innovation Solution
Incorporating a first and second stage hydrocracking reactor into a common unit, where the gas phase from the first stage is separated and replaced with clean scrubbed recycle gas, and unconverted oil is processed separately to minimize hydrogen sulfide and ammonia absorption, allowing for efficient hydrocracking with a single unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a two-stage hydrocracking process is used, then a clean reaction environment is provided with removed sulfur and nitrogen, but equipment cost and operational complexity increase
Solution Approach 1:
The patent combines the first stage hydrocracking reactor and the second stage hydrocracking reactor into a single integrated reactor unit. The first stage catalyst bed is positioned at the top and the second stage catalyst bed is positioned at the bottom, allowing both stages to operate simultaneously in one piece of equipment. This merging eliminates the need for separate reactor vessels, separators, and associated equipment, thereby reducing equipment cost and operational complexity while maintaining the clean reaction environment benefit.
Solution Approach 2:
The single reactor unit is segmented into two distinct catalyst beds with different functions: the first stage catalyst bed (top) performs initial hydrocracking and sulfur/nitrogen removal, while the second stage catalyst bed (bottom) performs further hydrocracking in a clean environment. This segmentation allows the process to achieve two-stage functionality within a single integrated unit, resolving the contradiction between process effectiveness and equipment complexity.
2Reliability
If a two-stage hydrocracking process is used, then sensitive catalysts can be used in a clean environment, but operational cost increases
Solution Approach 1:
By merging both catalyst beds into one reactor unit, the patent eliminates the operational complexities associated with managing separate reactors, including multiple feed systems, separate separation equipment, and coordinated operation. The integrated design simplifies operational procedures and reduces labor and maintenance costs, making the system more economical to operate while still allowing sensitive catalysts to function in a clean environment.
3Productivity
If unconverted oil is recycled to the first stage, then material utilization is improved, but hydrogen sulfide and ammonia absorption increases
Solution Approach 1:
The patent segments the recycling stream into two separate paths: unconverted oil from the first stage is recycled to the second stage (not back to the first stage), and a portion of the second stage effluent is recycled to the first stage. This segmentation prevents the re-absorption of hydrogen sulfide and ammonia that would occur if unconverted oil were recycled back to the first stage, while still maintaining high material utilization through the alternative recycling paths.
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
This approach reduces equipment costs and maintains a clean reaction environment, enabling effective hydrocracking with reduced operational expenses and improved catalyst performance.
Implementation Method 1
hydrocracking can include processes which convert hydrocarbons in the presence of hydrocracking catalyst and hydrogen to more valuable products
Implementation Method 2
separating the first hydrocracked stream in a hydrocracking reactor vessel to provide a vapor first hydrocracked stream and a liquid first hydrocracked stream
Implementation Method 3
hydrocracking can include processes which convert hydrocarbons in the presence of hydrocracking catalyst and hydrogen to more valuable products
Data Source
AI summary
An apparatus and process is disclosed for hydrocracking a hydrocarbon feed in a hydrocracking reactor and hydrocracking a liquid first hydrocracked stream and a recycle oil stream in a second hydrocracking reactor. A vapor first hydrocracked stream and the second hydrocracked stream are fractionated to provide the recycle oil stream.