Multi-Stage Alkane ODH Reactor with Inter-Stage Cooling
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Solution Overview
Problem
Existing oxidative dehydrogenation (ODH) processes face challenges with thermal runaway and inefficient energy management, leading to poor selectivity and safety concerns due to excessive heat generation and side reactions, which are not adequately addressed in current reactor designs.
Innovation Solution
A multi-stage reactor system with adiabatic reaction stages and controlled oxygen feed limits, combined with inter-stage cooling, to manage reaction heat and prevent thermal runaway, achieving high selectivity and efficiency without the need for additional thermal moderators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If oxidative dehydrogenation is carried out at higher temperatures to increase reaction rate, then productivity is improved, but thermal runaway occurs leading to poor selectivity and safety concerns
Solution Approach 1:
The reaction system is divided into multiple adiabatic reaction stages (first reaction stage, second reaction stage, etc.) with inter-stage cooling sections. Each stage operates at controlled temperature conditions, preventing thermal runaway while maintaining high overall productivity through sequential processing.
Solution Approach 2:
An inter-stage cooling section acts as an intermediary between reaction stages, removing excess heat generated in the first stage before the feed enters the second stage. This mediator prevents heat accumulation that would lead to thermal runaway and selectivity loss.
2Productivity
If excess oxygen is provided to drive the oxidation reaction, then productivity is improved, but unwanted side reactions increase producing CO and CO2
Solution Approach 1:
Oxygen feed is segmented and controlled at each reaction stage rather than provided in excess at once. The first reaction stage uses controlled oxygen to achieve partial conversion, and the second stage processes the effluent further, preventing excessive oxidation to CO and CO2 while maintaining high productivity.
Solution Approach 2:
The process uses partial oxidation in the first reaction stage with controlled oxygen amounts, then processes the intermediate effluent in a second stage. This partial action approach prevents complete oxidation to unwanted CO and CO2 while achieving high overall conversion and selectivity.
3Device complexity
If single-stage reactor design is used to simplify the process, then device complexity is reduced, but thermal runaway cannot be prevented
Solution Approach 1:
The reactor system is segmented into multiple adiabatic reaction stages with inter-stage cooling sections, providing inherent thermal control through the segmented design. This segmentation prevents thermal runaway while maintaining practical device complexity through modular configuration.
Solution Approach 2:
The effluent from the first reaction stage self-cools in the inter-stage cooling section before entering the second stage, providing automatic thermal management. This self-service cooling mechanism prevents thermal runaway without requiring complex external cooling systems.
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 achieves high ethylene selectivity (>90%) and ethane conversion (10-50%) while minimizing unwanted products, ensuring reactor safety and reducing energy consumption.
Implementation Method 1
oxidative dehydrogenation of the alkanes with oxygen in the presence of the catalyst
Implementation Method 2
significant heat is released by the exothermic reactions
Implementation Method 3
cooling the effluent stream from reaction stages 1 through n-1
Data Source
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AI summary
A process for producing an alkene-containing product stream by oxidative dehydrogenation is disclosed herein. The process comprises providing a primary feedstream comprising a C2 – C6 alkane through a reactor system having total "n" reaction stages in series. The "n" can vary from 2 to 20. The process further comprises providing a secondary feedstream comprising oxygen to each of the reaction stages and producing an effluent stream comprising alkene, alkane, and oxygen from each of the reaction stages. The effluent stream from reaction stages 1 through "n-1" is cooled to generate an input feedstream that is fed to the immediate next reaction stage. The process thus produced an alkene-containing product stream in the "n" th reaction stage. Each of the reaction stages is substantially adiabatic.