Synthesis Gas Methanation Process with Shift Reactor Inert Control
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Solution Overview
Problem
Existing methanation processes face inefficiencies due to the need for large and energy-consuming compressors to manage the exothermicity of the methanation reaction, and require complex recirculation methods to achieve the desired H2:CO molar ratio and control reaction heat.
Innovation Solution
The process introduces high inert content through a preliminary shift step with steam addition and feeds fresh synthesis gas directly to subsequent methanation reactors, using a control system to adjust steam and gas flowrates to maintain equilibrium and control exothermicity without heavy recirculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a compressor is used to recirculate inert matter to mitigate the thermal effect of the methanation reaction, then the exothermicity control is improved, but the device complexity and energy consumption increase
Solution Approach 1:
The patent extracts the compressor and recirculation system from the methanation process by using a different approach: steam is introduced in the shift reactor to generate CO2 and H2O, which then serve as inerts in the methanation reactor. This eliminates the need for mechanical recirculation equipment while maintaining temperature control.
Solution Approach 2:
The patent introduces steam as an intermediary substance that undergoes shift reaction to produce CO2 and H2O. These reaction products then act as the inert matter needed for temperature control in the methanation reactor, replacing the need for external recirculation systems.
2Productivity
If synthesis gas is treated to achieve the desired H2:CO molar ratio through shift reaction and CO2 removal, then the methanation reaction efficiency is improved, but the process complexity increases
Solution Approach 1:
The shift reactor serves multiple functions: it adjusts the H2:CO ratio for optimal methanation, generates CO2 and H2O that serve as inerts for temperature control, and eliminates the need for separate CO2 removal equipment. This multi-functionality simplifies the overall process while maintaining efficiency.
Solution Approach 2:
The patent converts the CO2 that would normally need to be removed as an impurity into a beneficial inert substance that helps control the exothermicity of the methanation reaction. By introducing steam to generate CO2 through shift reaction, what was previously a harmful impurity becomes a useful process aid.
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 effective control of methanation reaction exothermicity and efficient methane production by using steam and inert gases, reducing the need for large compressors and complex recirculation systems, thereby enhancing process efficiency and reliability.
Implementation Method 1
a first fraction of the synthesis gas to treat is conveyed to a shift reactor together with a steam flowrate fed from a steam feed circuit
Implementation Method 2
The methanation reaction implies the reaction of H2 and CO in a molar ratio of 3:1. This reaction is performed on a catalyst and is very fast and exothermic.
Implementation Method 3
The methanation reaction implies the reaction of H2 and CO in a molar ratio of 3:1. This reaction is performed on a catalyst and is very fast and exothermic.
Implementation Method 4
The methanation reaction implies the reaction of H2 and CO in a molar ratio of 3:1. This reaction is performed on a catalyst and is very fast and exothermic.
Data Source
AI summary
In a synthesis gas methanation process, at least one first fraction of synthesis gas to treat is fed, together with steam, to a shift reactor where a shift reaction occurs; the gas flow produced in the shift reactor is then fed to a first methanation reactor where a methanation reaction occurs and then to further second methanation reactors in series, where further methanation reactions, performed with the addition of fresh synthesis gas which has not been subjected to the shift reaction.