Oxygen-Permeable Membrane Thermal Management in Hydrocarbon Reforming
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Solution Overview
Problem
Oxygen-permeable membranes used in hydrocarbon reforming face overheating due to Joule heat generation, leading to reduced oxygen permeability and potential membrane failure, with existing technologies failing to effectively manage thermal balance and achieve efficient partial oxidation and steam reforming reactions.
Innovation Solution
A method and apparatus that utilize the heat from steam reforming and the entropy change of partial oxidation reactions to remove Joule heat, maintaining thermal balance and controlling the ratio of partial oxidation to steam reforming reactions to prevent membrane overheating, while using a composite oxygen-permeable membrane with optimal thickness for efficient oxygen flux and Joule heat conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxygen-permeable membrane is used for partial oxidation reforming, then oxygen isolation and promotion of partial oxidation reactions are achieved, but Joule heat generation causes membrane overheating and potential failure
Solution Approach 1:
The patent converts the harmful Joule heat into a beneficial component by introducing it into the endothermic steam reforming reaction zone. The heat that would otherwise cause membrane overheating and degradation is now utilized to drive the steam reforming reaction, simultaneously protecting the membrane and improving reaction efficiency.
Solution Approach 2:
The patent introduces steam as an intermediary substance that mediates between the oxygen-permeable membrane and the hydrocarbon feed. The steam absorbs Joule heat through endothermic reforming reactions, acting as a thermal buffer that protects the membrane from overheating while enabling controlled partial oxidation.
2Productivity
If steam reforming is used to produce hydrogen, then high hydrogen production quantity is achieved, but high endothermic tendency makes reaction difficult to start
Solution Approach 1:
The patent merges partial oxidation reforming and steam reforming into a single integrated process. The exothermic partial oxidation provides the heat necessary to initiate and sustain the endothermic steam reforming reaction, eliminating the startup difficulty while maintaining high hydrogen production capacity.
Solution Approach 2:
The patent performs preliminary partial oxidation of hydrocarbons using oxygen from the air side of the membrane before introducing steam. This preliminary action generates the heat and reactive intermediates needed to initiate the steam reforming reaction, making the overall process easier to start and control.
3Ease of operation
If partial oxidation reforming is used, then easy reaction initiation is achieved, but lower hydrogen production quantity compared to steam reforming
Solution Approach 1:
The patent combines partial oxidation and steam reforming reactions in a unified process. The partial oxidation provides easy reaction initiation through its exothermic nature, while the subsequent steam reforming boosts hydrogen production quantity, achieving both benefits simultaneously.
Solution Approach 2:
The patent establishes a continuous reaction sequence where partial oxidation immediately precedes and feeds into steam reforming. This continuous action ensures that the heat and reactive species generated by partial oxidation are continuously utilized to drive steam reforming, maintaining both ease of initiation and high productivity throughout the process.
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 extends the life of the oxygen-permeable membrane, achieves high hydrogen production efficiency, and downsizes the reforming apparatus by maintaining thermal balance and optimizing reaction ratios, ensuring stable and efficient hydrocarbon reforming.
Implementation Method 1
uses a material having both oxide ionic conductivity and electronic conductivity (an oxide-ion/electron hybrid conductor) as a separator that partitions a hydrocarbon gas and air, thereby isolating pure oxygen necessary in the partial oxidation reforming from the air by taking ΔG of the partial oxidation reaction (in more specific terms, the oxygen concentration gradient) as a driving force
Implementation Method 2
uses a material having both oxide ionic conductivity and electronic conductivity
Implementation Method 3
uses a material having both oxide ionic conductivity and electronic conductivity
Implementation Method 4
the heat generated in association with the partial oxidation reforming reaction (ΔH) is regarded as excess heat and is removed by the endothermic reaction of the steam reforming
Implementation Method 5
the use of oxygen is not so excellent in the production quantity of hydrogen but allows the reaction to be readily started because of its high exothermic tendency
Data Source
AI summary
To provide a method and an apparatus for reforming a hydrocarbon with a prolonged life of an oxygen-permeable membrane and a high recovery rate.The oxygen-permeable membrane absorbs the free energy change, ΔG, of a partial oxidation reforming reaction and then converts it into work for oxygen isolation and Joule heat, Q. Here, as seen in Table 1 and FIG. 1, ΔG of the partial oxidation reforming reaction is approximately ten times larger than ΔH, and further increases as the temperature increases. The generated Joule heat, Q, has to be removed at a high efficiency, and this removal process is achieved by returning a portion of the Joule heat to the system as the entropy change, TΔS, of the partial oxidation reaction itself and by steam reforming using the total energy change, ΔH.