Parallel Reactor Methanation with Purge Recirculation
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Solution Overview
Problem
Conventional methods for producing methane from CO2-containing gases face challenges in achieving continuous production and maintaining high concentration and purity, often requiring external energy and complex apparatus setups.
Innovation Solution
The use of two or more reactors with CO2 storage-reduction catalysts disposed in parallel, where one reactor stores CO2 and the other reduces it, with a purge gas recirculation system to prevent CO2 emission and enhance methane production using a downstream methanation catalyst.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional methods use a single reactor for CO2 storage and methanation, then the apparatus is simpler, but continuous methane production cannot be achieved
Solution Approach 1:
The patent divides the single reactor into multiple reactors (first and second reactors) that operate in parallel. Each reactor performs different functions at different times - one stores CO2 while the other produces methane, enabling continuous production without requiring a single complex reactor to handle all functions simultaneously.
Solution Approach 2:
The patent implements periodic switching between CO2 storage mode and methanation mode across the multiple reactors. By alternately switching the functional mode of each reactor in a periodic cycle, the system maintains continuous methane production while keeping each individual reactor relatively simple in design.
2Reliability
If purge gas is supplied to remove O2 after CO2 storage, then O2 is effectively removed, but stored CO2 is desorbed and methane concentration decreases
Solution Approach 1:
The patent extracts the O2 removal function from the main methanation process by dedicating specific time periods and reactor configurations solely for purge gas treatment. This separates the oxygen removal step from the methane production step, preventing CO2 desorption during purification and maintaining high methane concentration in the final product.
Solution Approach 2:
The patent performs CO2 storage completely before introducing purge gas for O2 removal. By completing the CO2 uptake phase first and then switching to purge mode, the system ensures maximum CO2 is stored on the catalyst before any desorption can occur, thereby maintaining high methane concentration when methanation begins.
3Manufacturing precision
If CO2 separation and recovery are performed individually before methanation, then CO2 purity is improved, but external energy supply and complex apparatus are required
Solution Approach 1:
The patent merges the CO2 separation function and methanation function into a single integrated reactor system using the CO2 storage-reduction catalyst. The catalyst performs both CO2 uptake from the gas mixture and subsequent methanation in the same reactor, eliminating the need for separate CO2 separation apparatus and the external energy they would require.
Solution Approach 2:
The CO2 storage-reduction catalyst is designed to perform multiple functions: CO2 adsorption, O2 removal, and methanation. This multi-functional catalyst eliminates the need for separate CO2 separation and purification steps, reducing both apparatus complexity and external energy requirements while maintaining high CO2 purity for methanation.
4Productivity
If temperature is raised to 600°C or more for carbon methanation on ferrite, then methane production is achieved, but external energy supply is required
Solution Approach 1:
The patent changes the operating temperature parameter from high temperature (600°C or more) to moderate temperature (250-400°C) by using the CO2 storage-reduction catalyst. This parameter change enables the methanation reaction to proceed at lower temperatures using the heat generated by the reaction itself, eliminating the need for external energy supply while maintaining productive methane generation.
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 allows for continuous methane production with improved concentration and purity, preventing CO2 emission and reducing the need for external energy by utilizing heat from the methanation reaction.
Implementation Method 1
a CO2 storage-reduction catalyst having CO2 storage capacity and methane generation ability
Implementation Method 2
methane generation ability
Implementation Method 3
heat generated in the methanation reaction
Data Source
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AI summary
An apparatus of producing methane from a CO2-containing gas comprises: at least two first reactors with a CO2 storage-reduction catalyst having a CO2 storage capacity and a methane generation ability disposed in parallel; at least one second reactor provided with a methanation catalyst; means for supplying purge gas; and means for supplying reducing gas, wherein the means for supplying purge gas and for supplying reducing gas are disposed upstream of the first reactors, the second reactor is disposed downstream of the first reactors, and a gas outlet of one of the first reactors is connected to a gas inlet of at least one different one of the first reactors via a purge gas recirculation line which supplies a purge gas emitted from the gas outlet of the one first reactor into the gas inlet of the different first reactor.