Flexible Reactor Switching RWGS and Partial Oxidation Modes
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Solution Overview
Problem
Current Reverse Water Gas Shift (RWGS) processes face challenges in efficiently converting carbon dioxide to carbon monoxide at high temperatures on a large scale, requiring high heat transfer and catalysts that are costly and prone to deactivation, while also struggling with intermittency issues related to renewable energy sources, leading to discontinuous operation of downstream processes.
Innovation Solution
A flexible process that switches between reverse water gas shift and partial oxidation modes within the same reaction vessel using a burner with coaxial channels, eliminating the need for catalysts and external heating/cooling, by introducing feed streams and oxygen in specific configurations to maintain temperatures between 1000°C to 1500°C, allowing seamless operation without equipment changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high temperatures (around 1200°C) are used to efficiently convert carbon dioxide to carbon monoxide via RWGS reaction, then conversion efficiency is improved, but heat transfer requirements and engineering complexity increase substantially
Solution Approach 1:
The invention combines the endothermic RWGS reaction zone and exothermic combustion zone into a single integrated reactor system. The combustion of hydrogen or methane provides direct in-situ heating to the RWGS reaction zone, eliminating the need for complex external heat transfer systems while achieving the required high temperatures for efficient carbon dioxide conversion.
Solution Approach 2:
The system uses self-generated heat from the combustion of hydrogen or methane feedstocks to provide the thermal energy required for the RWGS reaction. This internal heat generation eliminates dependence on external heating systems and enables the reactor to self-maintain the high temperatures needed for high conversion efficiency.
2Temperature
If catalysts are used to enable RWGS reaction at lower temperatures (600-1000°C), then operating temperature is reduced, but catalyst cost and susceptibility to deactivation increase
Solution Approach 1:
The invention replaces expensive, fragile catalysts with a simpler catalyst-free or minimal-catalyst system that uses high temperature combustion. The approach accepts the need for high temperatures but eliminates catalyst-related reliability issues, using instead a more robust thermal process that is resistant to deactivation by sulfur and other poisons.
3Object-generated harmful factors
If renewable energy sources are used to provide hydrogen, then carbon footprint is reduced, but intermittency causes discontinuous operation of downstream processes
Solution Approach 1:
The reactor is designed to universally accept multiple feedstock options - it can operate with hydrogen from renewable sources during available periods, and switch to methane or other hydrocarbons during intermittency periods. This multi-functionality ensures continuous operation of downstream processes while maintaining low carbon footprint when renewable hydrogen is available.
Solution Approach 2:
The system dynamically adjusts its operation mode based on feedstock availability. It can switch between RWGS mode (using hydrogen and carbon dioxide) and partial oxidation mode (using methane and oxygen), allowing it to adapt to the intermittency of renewable energy sources while maintaining continuous synthesis gas production.
4Adaptability or versatility
If separate reactors are used for RWGS and partial oxidation processes, then process flexibility is improved, but capital expenditure increases
Solution Approach 1:
The invention merges the RWGS reactor and partial oxidation reactor into a single integrated unit. The same reactor vessel can operate in RWGS mode when hydrogen is available, or switch to partial oxidation mode when methane is used as feedstock. This consolidation reduces capital expenditure while maintaining the flexibility to adapt to different feedstock conditions.
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 enables efficient and continuous conversion of carbon dioxide and natural gas to carbon monoxide, reducing capital expenditures and ensuring a constant synthesis gas feedstock supply, even during intermittency, by using internal combustion reactions to provide heat and maintaining high temperatures without external heating or cooling.
Implementation Method 1
performing a reverse water gas shift reaction at elevated temperature, wherein (a) at least feed stream (1) and an oxygen rich gas stream are introduced into the reaction vessel via the burner in separate feed streams
Implementation Method 2
performing a partial oxidation reaction at elevated temperature, wherein (d) at least feed stream (2) and an oxygen rich gas stream are introduced into the reaction vessel via the burner in separate feed streams
Implementation Method 3
the hydrogen and oxygen in the hydrogen rich gas stream and oxygen rich gas stream undergo a combustion reaction upon entering the reaction vessel, thereby providing the heating energy required for the reverse water-gas shift reaction
Data Source
AI summary
The present invention relates to a process for converting feed streams selected from (1) a gas stream comprising carbon dioxide and a hydrogen rich gas stream; (2) a methane rich gas stream; and (3) a combination of feed streams (1) and (2) into a product stream comprising carbon monoxide, water and hydrogen. The process may include introducing feed streams selected from (1), (2) or (3) and oxygen into a reaction vessel and switching modes between performing method I or method II in the reaction vessel wherein no catalyst is present. The reaction vessel may be provided with a burner located at the top of the reaction vessel, the burner may include coaxial channels for the separate introduction of the different gas streams. Method I may be a reverse water gas shift reaction at elevated temperature. Method II may be a partial oxidation reaction at elevated temperature.