LPG Conversion via Series Fixed-Bed Reactors
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Solution Overview
Problem
Current processes for converting LPG to higher hydrocarbons, including aromatic hydrocarbons, face challenges such as catalyst deactivation due to coke formation, mechanical stress on catalysts in circulating or moving beds, and inefficient space-time yield, which leads to higher reactor sizes and lower catalyst utilization.
Innovation Solution
A process involving a series of reaction zones where only a subset are operated under conversion conditions, with a temperature profile that increases through the zones to maximize conversion and minimize coke formation, and catalyst regeneration, allowing for continuous operation without physical catalyst movement, thereby maintaining catalyst activity and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If circulating fluidized bed reactors or moving bed reactors are used for aromatization, then continuous catalyst regeneration is enabled, but the catalyst is subjected to mechanical forces (grinding and attrition, dust formation) and an expensive solids transport system is required
Solution Approach 1:
The process divides the catalyst system into multiple fixed bed reactors (first bed, second bed, third bed) that can be independently operated and regenerated. This segmentation allows continuous operation while avoiding the need for complex solids transport systems, as each bed remains stationary during operation and regeneration alternates between beds.
Solution Approach 2:
The process implements periodic regeneration by alternating between operating the first bed while regenerating the second bed, then switching to operate the second bed while regenerating the first bed. This periodic action enables continuous aromatization while simplifying the system by eliminating complex solids transport mechanisms.
2Duration of action of stationary object
If circulating fluidized bed reactors or moving bed reactors are used for aromatization, then continuous catalyst regeneration is enabled, but mechanical stress on catalysts increases causing grinding and attrition
Solution Approach 1:
By dividing the system into multiple fixed beds that can be independently regenerated, the catalyst remains stationary in each bed during operation, eliminating mechanical stress from fluidization and movement. This segmentation protects catalyst mechanical integrity while enabling continuous regeneration through alternating bed operation.
Solution Approach 2:
Instead of moving the catalyst through fluidized beds as in conventional processes, this invention inverts the approach by keeping catalyst beds fixed and moving the feedstock and products through them. This inversion eliminates mechanical stress on the catalyst while maintaining continuous operation capability.
3Reliability
If countercurrent moving bed with external catalyst reheating is used, then catalyst activity is maintained, but the increasing catalyst activity profile along the reactant flow direction leads to lower space-time yield and bigger reactor size
Solution Approach 1:
Each fixed bed reactor is designed with specific local conditions optimized for its function. The first bed operates with fresh catalyst at high activity, the second bed with partially deactivated catalyst, and the third bed with highly deactivated catalyst undergoing regeneration. This local quality differentiation creates a more uniform overall activity profile, improving space-time yield.
Solution Approach 2:
The process changes the operational parameters of each bed sequentially - the first bed operates at high temperature with fresh catalyst, the second bed operates with moderately deactivated catalyst, and the third bed undergoes regeneration. This parameter changes approach creates a more even catalyst activity distribution, improving productivity.
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 higher conversion rates of LPG to higher hydrocarbons, including aromatics, while controlling coke formation and maintaining catalyst activity, resulting in improved space-time yield and catalyst utilization compared to traditional methods.
Implementation Method 1
providing a quantity of catalytic material within each reaction zone
Implementation Method 2
heating at least a portion of the effluent of the said reaction zone designated as 1 to the inlet temperature of the reaction zone designated as 2
Data Source
AI summary
A process for converting a feed comprising C2-C4 alkanes to higher hydrocarbon(s) including aromatic hydrocarbon(s) in n reaction zones operated in series, wherein m reaction zones are not participating in the conversion process and only (n-m) reaction zones are operated under reaction conditions sufficient to convert at least a portion of said a feed comprising C2-C4 alkanes to an effluent having said higher hydrocarbon(s). An object of the present invention is to provide a process for converting LPG to higher hydrocarbon(s) including aromatic hydrocarbon(s) wherein a high reactant, i.e. ethane, propane and/or butane, conversion can be achieved.