BTX Hydrocracking Reactor Quench Gas Injection
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Solution Overview
Problem
In gas phase hydrocracking reactors, maintaining optimal temperature control and hydrogen to hydrocarbon ratios is challenging, leading to increased reactor volume and potential catalyst deactivation, while existing quenching methods either require complex systems or result in undesirable hydrogen to hydrocarbon ratios.
Innovation Solution
A process involving multiple reaction zones with interstitial quench zones where hydrogen and hydrocarbon gases are injected to maintain a hydrogen to hydrocarbon ratio of 1:1 to 4:1, decreasing with distance from the upstream end, allowing for precise control without heat exchangers, thus reducing reactor size and preventing catalyst deactivation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If quench gas injection is used for temperature control, then device complexity is reduced, but reactor volume increases
Solution Approach 1:
The patent changes the composition parameter of the quench gas from pure hydrogen to a mixture containing hydrocarbon components. This parameter change allows the quench gas to provide both cooling effect and maintain appropriate hydrogen-to-hydrocarbon ratio, thereby controlling reaction conditions without excessive reactor volume expansion
Solution Approach 2:
The patent introduces hydrocarbon components as intermediary substances in the quench gas that serve dual functions: they act as cooling agents to control temperature and simultaneously serve as reactants to maintain optimal hydrogen-to-hydrocarbon ratios in the reaction zones, eliminating the need for separate hydrogen supplementation systems
2Temperature
If large amounts of quench hydrogen gas are added for temperature control, then temperature control is improved, but hydrogen to hydrocarbon ratio becomes unbalanced
Solution Approach 1:
The patent changes the compositional parameters of the quench gas from pure hydrogen to a mixture containing both hydrogen and hydrocarbon components. This allows simultaneous achievement of effective temperature control through cooling and maintenance of appropriate hydrogen-to-hydrocarbon ratios for optimal reaction performance
Solution Approach 2:
The quench gas is designed to perform multiple functions simultaneously: it provides cooling effect to control temperature, maintains hydrogen-to-hydrocarbon ratio within desired ranges, and supplies hydrocarbon reactants to the reaction zones. This multi-functionality eliminates the trade-off between temperature control and ratio balance
3Temperature
If heat exchangers are used for interstage cooling, then temperature control is improved, but device complexity increases
Solution Approach 1:
The patent extracts and eliminates the heat exchanger components from the reaction system. Instead of using external heat exchange equipment for interstage cooling, the system uses direct quench gas injection into the reaction stream, thereby achieving temperature control while significantly reducing device complexity and eliminating additional piping requirements
Solution Approach 2:
The patent uses pneumatic injection of quench gas directly into the reaction stream to achieve cooling. This pneumatic approach replaces complex thermal heat exchange systems with a simpler gas-phase mixing and cooling mechanism, reducing equipment complexity while maintaining effective temperature control
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 effectively controls temperature and hydrogen to hydrocarbon ratios, reducing reactor volume, preventing catalyst deactivation, and achieving high benzene purity while minimizing capital expenditure.
Implementation Method 1
injecting a second portion of the hydrogen gas into at least one of the quench zones and injecting a second portion of the hydrocarbon gas into at least one of the quench zones
Implementation Method 2
each of the reaction zones has a bed of a hydrocracking catalyst contained therein
Implementation Method 3
process for hydrocracking a feedstream comprising hydrocarbons to obtain BTX
Implementation Method 4
In exothermic industrial fixed-bed reactors, reactor temperature increases as the reacting stream moves down through the catalyst bed
Data Source
Figure 1~3
Figure 4~5
AI summary
The invention relates to a process for hydrocracking a feedstream comprising hydrocarbons to obtain BTX in a gas phase hydrocracking reactor system which comprises (i) an upstream end and a downstream end, (ii) a plurality of successive reaction zones distributed along the reactor between the upstream end and the downstream end, wherein each of the reaction zones has a bed of a hydrocracking catalyst contained therein and (iii) a plurality of quench zones, the quench zones being distributed along the reactor and each being situated between successive reaction zones, wherein the process comprises: (a) injecting a first portion of a hydrogen gas into the upstream end and a first portion of a hydrocarbon gas into the upstream end and (b) injecting a second portion of the hydrogen gas into at least one of the quench zones and injecting a second portion of the hydrocarbon gas into at least one of the quench zones, wherein the molar ratio between hydrogen and hydrocarbons entering each of the reaction zones is 1 :1 to 4:1, wherein the molar ratio between hydrogen and hydrocarbons entering the reaction zones decreases with the distance of the reaction zone from the upstream end of the reactor.