Process and system for cracking a hydrocarbon feed
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Solution Overview
Problem
Conventional hydrocracking processes face challenges in efficiently processing lighter hydrocarbon feeds at mild conditions, particularly in achieving effective separation of hydrogen and product streams while minimizing energy consumption and capital expenditure.
Innovation Solution
The process involves hydrocracking lighter hydrocarbon feeds at moderate pressures, using multiple hydrocracking units and separation steps, including absorption and cold separation processes, to produce high-purity streams of hydrogen, benzene, toluene, xylene, and other hydrocarbons, with recycling of heavy streams to enhance separation efficiency and reduce energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional hydrocracking processes operate at high pressure to efficiently separate hydrogen and products via liquid-vapor flash separation, then separation efficiency is improved, but capital expenditure and energy consumption increase
Solution Approach 1:
The patent changes the operating pressure parameter from conventional high pressure (>6 MPa) to moderate pressure (0.3-5.0 MPa, below critical pressure of C5-C12 feeds). This parameter change enables the use of alternative separation methods (absorption and cold separation) that are more energy-efficient while maintaining effective separation of hydrogen and hydrocarbon products
Solution Approach 2:
The patent replaces the mechanical liquid-vapor flash separation system with an absorption-based separation system using absorbing liquids (such as N-methyl-2-pyrrolidone or sulfolane). This substitution allows effective separation at moderate pressures without requiring the high-pressure mechanical separation systems of conventional processes
2Reliability
If conventional hydrocracking processes use high pressure operation, then liquid-vapor flash separation is efficient, but capital expenditure increases
Solution Approach 1:
The patent changes the operating pressure parameter from conventional high pressure (>6 MPa) to moderate pressure (0.3-5.0 MPa). This parameter change reduces capital expenditure by enabling the use of less expensive absorption-based separation equipment and cold separation units instead of high-pressure flash separation equipment
Solution Approach 2:
The patent employs absorbing liquids (such as N-methyl-2-pyrrolidone or sulfolane) that can be readily processed and regenerated. These absorbing liquids enable effective separation at moderate pressures using simpler, less expensive equipment compared to high-pressure separation systems
3Use of energy by stationary object
If hydrocracking lighter hydrocarbon feeds at mild conditions below critical pressure, then energy consumption and capital expenditure are reduced, but separation efficiency may deteriorate
Solution Approach 1:
The patent introduces absorbing liquids (N-methyl-2-pyrrolidone or sulfolane) as intermediary substances to facilitate separation at moderate pressures. These absorbing liquids selectively absorb specific hydrocarbon components from the effluent, enabling effective separation without requiring high pressure or excessive energy input
Solution Approach 2:
The patent segments the separation process into multiple stages: first absorption step to remove light ends, second absorption step for further purification, and cold separation. This segmented approach achieves high separation efficiency at moderate pressures by breaking down the separation task into manageable steps
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 achieves high recovery rates (>90%) of hydrocarbon products with improved separation efficiency and reduced energy consumption, avoiding extreme temperature profiles that could lead to freezing or corrosion issues.
Implementation Method 1
absorbing benzene, toluene, xylene, or a combination comprising at least one of the foregoing from a hydrocracking product stream into an absorbing liquid to form a first heavy stream and a first light stream
Implementation Method 2
separating the first light stream in a separation process comprising a cold separation process to form at least two of a hydrogen stream, C1 stream, C2 stream, C3 stream, C4 stream, a C5+ stream
Data Source
AI summary
A process for hydrocracking a hydrocarbon feed is provided. The process comprises hydrocracking the hydrocarbon feed to produce a first hydrocracking product stream, separating the first hydrocracking product stream to form a gas stream and a liquid stream, hydrocracking the liquid stream to produce a second hydrocracking product stream, separating the second hydrocracking product stream to form a first light stream and a first heavy stream comprising benzene, toluene, xylene, C9+ hydrocarbon, or a combination comprising at least one of the foregoing, purifying the gas stream to form a purified gas stream, and separating the purified gas stream to form at least two of a hydrogen stream, C1 stream, C2 stream, C3 stream, C4 stream, C5+ stream, or a combination comprising at least one of the foregoing.