Fluidized Riser Reactor for Paraffin Oxydative Dehydrogenation
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Solution Overview
Problem
Paraffin dehydrogenation processes are limited by equilibrium constraints, requiring high temperatures that lead to thermal cracking and increased utility consumption, resulting in reduced conversion and selectivity, as well as higher capital and operating costs due to multi-stage heating and thermal reactions.
Innovation Solution
The process involves oxidative dehydrogenation in a fluidized riser reactor with a catalyst that selectively dehydrogenates hydrocarbons and oxidizes hydrogen, maintaining the hydrocarbon mixture at desired temperatures through controlled oxygen injection, shifting the equilibrium and minimizing thermal cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high temperature is used to overcome equilibrium constraints in dehydrogenation, then conversion is improved, but thermal cracking increases and selectivity deteriorates
Solution Approach 1:
The patent changes the temperature parameter profile from constant high temperature to a controlled gradient, maintaining lower temperatures in the reaction zone to prevent thermal cracking while achieving high conversion through the fluidized bed's enhanced mass and heat transfer characteristics
Solution Approach 2:
The fluidized catalyst bed acts as an intermediary that facilitates the dehydrogenation reaction at lower temperatures by providing large surface area contact and efficient heat distribution, eliminating the need for high temperature operation that causes thermal cracking
2Productivity
If high temperature is used to overcome equilibrium constraints, then conversion is improved, but utility consumption increases
Solution Approach 1:
The patent changes the temperature parameter from high constant temperature to controlled lower temperature operation with heat integration, significantly reducing utility consumption for heating while maintaining high conversion through fluidized bed efficiency
Solution Approach 2:
The system uses self-generated heat from the exothermic cracking reactions and heat exchange between fluidized bed zones to maintain reaction temperatures, eliminating the need for external utility heating and achieving energy self-sufficiency
3Productivity
If multi-stage heating is used to achieve desired conversion, then conversion is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple heating stages into a single fluidized bed reactor with internal heat circulation, where hot catalyst particles and gas phases transfer heat directly to incoming feed, eliminating the need for separate external heating stages and reducing device complexity
4Productivity
If extended residence time is used to improve conversion, then conversion is improved, but thermal reactions increase
Solution Approach 1:
The patent changes the temperature parameter to lower operating conditions in the fluidized bed, allowing extended residence time for complete conversion without triggering unwanted thermal reactions, as the efficient mass transfer compensates for lower temperature driving force
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 significantly increases conversion per pass while maintaining selectivity, reducing thermal cracking and utility consumption by maintaining a controlled temperature profile within the reactor, thereby enhancing the efficiency and cost-effectiveness of the dehydrogenation process.
Implementation Method 1
the catalyst and the feed are contacted under dehydrogenation conditions to dehydrogenate the hydrocarbons to form olefins and hydrogen
Implementation Method 2
An oxygen-containing gas is introduced into the plurality of injection ports to oxidize a portion of the hydrogen formed from the dehydrogenation reaction
Implementation Method 3
maintaining the hydrocarbon mixture at desired temperatures through controlled oxygen injection
Data Source
AI summary
A process of oxidative dehydrogenation in a fluidized riser reactor is described. Hydrocarbon feed and catalyst are fed to the bottom of the fluidized riser reactor. Part of the hydrogen produced in the dehydrogenation reaction is oxidized using oxygen introduced into the riser reactor through oxygen injection ports to produce the heat required for the dehydrogenation reaction.