Fluidized Fuel Gas Combustor for Catalytic Dehydrogenation
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Solution Overview
Problem
Conventional catalyst reactivation processes in catalytic dehydrogenation fail to provide sufficient heat for endothermic dehydrogenation reactions, leading to catalyst deactivation due to uneven fuel distribution and maldistribution of fuel gas in fluidized bed combustors, which affects alkene production and process economics.
Innovation Solution
A fluidized fuel gas combustor system with strategically placed fuel gas and air injection diffusers, grid assemblies, and refractory materials to ensure even mass distribution of fuel gas and air, maximizing combustion efficiency and minimizing catalyst deactivation, comprising a vessel with specific geometric configurations and optional grid assemblies to optimize fuel and air distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If fuel gas is injected through distributor pipes in the combustor, then heat is provided for the endothermic dehydrogenation reaction, but maldistribution of fuel gas occurs causing catalyst deactivation
Solution Approach 1:
The combustor is divided into multiple zones with different types of diffusers (coarse and fine) arranged in specific patterns. The distributor pipes are segmented into multiple injection points along their length, with each segment injecting fuel gas at optimized locations to achieve uniform overall distribution while preventing local maldistribution that causes catalyst deactivation.
Solution Approach 2:
Different regions of the combustor receive different types of fuel gas diffusers tailored to local requirements. Coarse diffusers are placed in regions requiring higher fuel input, while fine diffusers are used in regions requiring precise fuel dosing. This localized optimization ensures uniform fuel distribution across the entire combustor cross-section, preventing catalyst deactivation while providing sufficient heat for the endothermic reaction.
2Manufacturing precision
If distributor pipes block a high percentage of combustor open area, then fuel distribution may improve, but the combustor floods and catalyst cannot backmix to form a dense bed
Solution Approach 1:
The distributor system is segmented into multiple thin pipe sections distributed across the combustor cross-section, rather than using fewer large-diameter pipes. This segmentation provides adequate fuel distribution coverage while maintaining sufficient open area for catalyst backmixing and bed formation. The segmented approach allows fuel injection without blocking the fluidization pathways.
Solution Approach 2:
The system utilizes gas flow dynamics to deliver fuel gas through the distributor pipes without creating excessive pressure drops or blocking the combustor. The fuel gas is injected at velocities and pressures optimized to distribute fuel evenly while maintaining the fluidization regime necessary for catalyst backmixing. The pneumatic design ensures that fuel distribution does not interfere with catalyst movement and bed formation.
3Device complexity
If fuel is injected at ambient temperature, then fuel distribution is simple, but fuel heats up in the distributor pipe causing density decrease and maldistribution
Solution Approach 1:
The fuel gas is pre-heated to a temperature closer to the combustor operating temperature before entering the distributor pipes. This preliminary heating action prevents excessive temperature differences between the fuel gas and surrounding environment, minimizing density changes and preventing maldistribution caused by thermal expansion within the distributor system. The pre-heating is performed in a controlled manner to avoid complexity while ensuring uniform fuel delivery.
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 system achieves uniform fuel distribution and enhanced combustion efficiency, reducing catalyst deactivation and increasing alkene production by ensuring sufficient heat is provided for the dehydrogenation reaction, thereby improving process economics.
Implementation Method 1
a fluidized fuel gas combustor system for a catalytic dehydrogenation process
Implementation Method 2
a plurality of air injection diffusers located in the lower portion of the vessel
Implementation Method 3
contacting such catalysts at high temperature (e.g. at least 450 degrees Celsius (°C) for an ethanol dehydration catalyst and at least 650 °C for a fluid catalyst cracking (FCC) catalyst) with air or another oxygen-containing gas
Implementation Method 4
The combustor is lined with a refractory material
Data Source
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AI summary
A fluidized fuel gas combustor system for a catalytic dehydrogenation process comprising a vessel having a lower portion and an upper portion; a plurality of air injection diffusers located in the lower portion of the vessel; a plurality of fuel gas injection diffusers located on fuel gas distributors disposed in the vessel and spaced apart from and above a plurality of air injection diffusers, wherein the fuel gas diffusers are placed in a manner to maximize even mass distribution of a fuel gas injected through the fuel gas diffusers in the vessel, wherein each fuel distributor comprises a tube having a plurality of fuel gas injection diffusers, one or more optional grid assemblies disposed in the vessel spaced apart from and above the plurality of air injection diffusers and paced apart from and below the fuel gas distributors to maximize even air mass distribution; and one or more grid assemblies disposed in the vessel spaced above the fuel gas distributors is provided.