Reverse Flow Reactor Regeneration Using High Heat Capacity Diluent
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Solution Overview
Problem
Reverse flow reactors face challenges in managing heat introduction during the regeneration step, leading to excessive temperature spikes and substantial pressure drops due to the large volume of diluent gas required, which increases operating costs and reactor size, necessitating a more efficient heat management solution.
Innovation Solution
Incorporating a high heat capacity gas such as CO2 or H2O as the diluent during the regeneration step, which reduces peak temperatures and laminar flame speed, allowing for a reduction in diluent volume and an increase in fuel usage, thereby mitigating pressure drops and enhancing reaction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a large volume of diluent gas is used during the regeneration step, then heat management is improved, but pressure drops increase and reactor size increases
Solution Approach 1:
The patent changes the physical parameter of the diluent gas by selecting gases with high heat capacity (such as CO2 and H2O) instead of conventional diluents. This parameter change allows the system to achieve effective heat management with a reduced volume of diluent gas, thereby resolving the contradiction between temperature control and gas volume requirements.
2Temperature
If a large volume of diluent gas is used during the regeneration step, then heat management is improved, but operating costs increase
Solution Approach 1:
By changing the composition parameter of the diluent gas to include high heat capacity gases like CO2 and H2O, the system achieves better temperature control with less gas volume. This reduces the energy required for gas handling and processing, thereby lowering operating costs while maintaining effective heat management.
3Productivity
If fuel usage is increased to provide heat for endothermic reactions, then reaction efficiency is improved, but peak temperatures become excessive
Solution Approach 1:
The patent introduces high heat capacity gases (CO2 and H2O) as intermediary substances that act as thermal buffers during the combustion process. These intermediaries absorb excess heat from the combustion zone, preventing excessive peak temperatures while still allowing sufficient fuel to be burned to provide the necessary heat for endothermic reactions, thus resolving the contradiction between reaction efficiency and 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
The use of high heat capacity gases as diluents decreases peak temperatures and laminar flame speed, reducing pressure drops and increasing the efficiency of endothermic reactions while maintaining reaction performance, thus optimizing the reverse flow reactor process.
Implementation Method 1
the diluent comprising 25.0 vol % or more of a gas having a heat capacity at 1500 K of 40 J/mol*K or more
Implementation Method 2
reacting a fuel mixture comprising fuel, 0.1 vol % or more of O2, and a diluent under combustion conditions in a combustion zone within a reactor to form a flue gas and to heat one or more surfaces in a reaction zone
Implementation Method 3
exposing a first reactant stream to the catalyst composition in the reaction zone at the regenerated surface temperature under endothermic reaction conditions
Data Source
AI summary
Systems and methods are provided for using a high heat capacity gas as at least a portion of the diluent during the regeneration step of a reverse flow reactor process. Instead of using nitrogen or air as the primary diluent gas, CO2 and/or H2O can be added as diluent gas for the regeneration step in the reaction cycle. Increasing the heat capacity of the diluent gas provides a reduction in the peak temperature within the reactor relative to the amount of fuel combusted during regeneration. This can allow for a reduction in the volume of diluent used during regeneration and/or an increase in the amount of fuel used. Reducing the volume of diluent can reduce the pressure drop during regeneration, which can provide a corresponding reduction in the amount of compression required for recycle of the diluent. Increasing the amount of fuel can allow for a corresponding increase in the amount of endothermic reaction performed during the reaction step.