Oxygen Transport Membrane Reactors for Hydrogen Decarbonization
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Solution Overview
Problem
Conventional steam methane reformers produce synthesis gas with lower hydrogen content and higher carbon monoxide levels, leading to inefficient carbon capture and increased CO2 emissions, as they rely on direct combustion of hydrocarbon tail gases, which limits hydrogen production efficiency and carbon utilization.
Innovation Solution
An oxygen transport membrane-based system that combusts PSA tail gas with high efficiency (90-95%) to produce heat for endothermic reforming reactions, allowing for higher H2/CO ratios and enabling carbon capture through concentrated CO2 streams, which can be further processed for purification and sequestration or used in downstream processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional steam methane reformers are used to produce synthesis gas, then hydrogen production is achieved, but the hydrogen content is lower and carbon monoxide levels are higher, reducing efficiency
Solution Approach 1:
The reforming process is divided into multiple stages: an initial reforming stage followed by a second-stage reforming stage. This segmentation allows the synthesis gas to undergo sequential treatment, progressively increasing hydrogen content and reducing carbon monoxide levels, thereby resolving the contradiction between productivity and hydrogen quantity.
Solution Approach 2:
The synthesis gas stream is continuously circulated between the reformer and the second-stage reformer, maintaining continuous useful action. This continuous circulation ensures that the gas undergoes repeated reforming and shifting reactions, progressively improving hydrogen content without interrupting the overall production process.
2Temperature
If direct combustion of hydrocarbon tail gases is used in fired reformers, then thermal management for endothermic reforming is achieved, but carbon capture efficiency is limited and CO2 emissions increase
Solution Approach 1:
The hydrocarbon tail gases that would normally be combusted and contribute to CO2 emissions are instead converted into a valuable fuel source. By using these gases as fuel in the second-stage reformer, the system generates the necessary heat for endothermic reactions while simultaneously reducing CO2 emissions through improved carbon capture efficiency in the PSA unit.
Solution Approach 2:
The system introduces pure oxygen from an oxygen transport membrane into the second-stage reformer, creating conditions for more efficient and controlled oxidation reactions. This accelerated oxidation provides the necessary thermal energy for reforming while enabling better control over combustion products and improving overall carbon utilization efficiency.
3Object-generated harmful factors
If oxygen transport membrane reforming systems are used, then carbon capture is improved, but hydrogen to carbon monoxide molar ratio decreases, reducing hydrogen production efficiency
Solution Approach 1:
The first-stage reforming process performs preliminary conversion of hydrocarbons to synthesis gas before the gas enters the oxygen transport membrane system. This preliminary action ensures that the gas is already partially converted, allowing the subsequent membrane-based reforming to focus on improving carbon capture without completely sacrificing the hydrogen to carbon monoxide ratio.
Solution Approach 2:
The system applies different reforming conditions to different portions of the synthesis gas stream. The first-stage reformer provides initial conversion, while the second-stage reformer with oxygen transport membrane provides enhanced carbon capture. This local differentiation of process quality allows optimization of both hydrogen production and carbon capture in different zones of the system.
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 system enhances hydrogen production efficiency, achieves higher carbon capture rates, and reduces CO2 emissions by converting hydrocarbon feedstocks into industrially valuable products while minimizing the need for amine-based capture systems.
Implementation Method 1
pure oxygen separated from air by the action of the membrane
Implementation Method 2
oxidation catalyst-containing oxygen transport membrane reactors
Implementation Method 3
oxy-combust a fuel gas comprising PSA tail gas
Implementation Method 4
heat from the oxidation reactions on the oxygen transport membrane reactor surface
Implementation Method 5
endothermic reforming reactions in the reformer
Implementation Method 6
natural gas and steam are reformed in nickel catalyst-containing reformer tubes
Implementation Method 7
synthesis gas can be subjected to water-gas shift reactions to react steam with the carbon monoxide in the synthesis gas
Implementation Method 8
the heat from the oxidation reactions on the oxygen transport membrane reactor surface provides the reaction heat for endothermic reforming reactions in the reforming reactor primarily via radiant heat transfer
Implementation Method 9
hydrogen is recovered by treating the hydrogen rich stream in a H2 PSA
Data Source
AI summary
A method and system for decarbonization of a hydrocarbon conversion process such as steam methane reforming process for hydrogen production utilizing oxygen transport membrane reactors. The system employs catalyst-containing reforming reactors for converting natural gas into synthesis gas which is further treated in high temperature or medium temperature water gas shift reactors and fed to a hydrogen PSA to produce hydrogen product. The system further employs oxygen transport membrane reactors thermally coupled to reforming reactors and configured to oxy-combust about 90% to about 95% of combustibles in PSA tail gas that may be optionally mixed with natural gas. The oxy-combustion product stream leaving the oxygen transport membrane reactors contains about 90% of the carbon provided to the feed of the reforming reactor. The carbon dioxide in the oxy-combustion product stream can be recovered and further purified for utilization or geologic storage or liquefied to form a liquid carbon dioxide product.