Hydrogen Production via Two-Stage PSA Desulfurization
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Solution Overview
Problem
Existing methods for generating hydrogen gas from hydrocarbon gas mixtures containing sulfur or sulfur compounds, such as natural gas, face challenges due to catalyst contamination and inability to remove sulfur compounds to the low ppb range required for fuel cell applications, leading to sulfur emissions exceeding permissible limits.
Innovation Solution
A method utilizing a two-stage pressure swing adsorption (PSA) process with specific adsorption materials like zeolites, active carbon, pillared clays, metal-organic frameworks (MOFs), and CMS, followed by a steam reformer, to desulfurize natural gas to a product gas with sulfur content in the ppb range, allowing for continuous operation without solid waste generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional steam reformer with standard catalysts is used to convert hydrocarbon gas mixture into hydrogen gas, then hydrogen production efficiency is improved, but the catalysts are contaminated by sulfur leading to reduced performance and reliability
Solution Approach 1:
The invention extracts and removes sulfur compounds from the hydrocarbon gas mixture before the gas enters the steam reformer. This is achieved through adsorption units that selectively capture sulfur compounds, preventing them from reaching and contaminating the reformer catalysts, thus protecting catalyst performance while maintaining hydrogen production efficiency
Solution Approach 2:
The invention performs preliminary desulfurization treatment of the hydrocarbon gas mixture before it undergoes steam reforming. By pre-removing sulfur compounds through adsorption, the system prevents catalyst contamination before it occurs, ensuring both high productivity and reliable catalyst operation throughout the process
2Ease of manufacture
If sulfur compounds are not removed from natural gas, then the gas can be used as fuel with acceptable emissions, but the sulfur content is too high for fuel cell applications requiring ppb range purity
Solution Approach 1:
The invention changes the sulfur content parameter of the natural gas from ppm range (suitable for fuel) to ppb range (required for fuel cells) through sequential adsorption processes. The system uses multiple adsorption units with different adsorbents that progressively reduce sulfur concentration to the required precision level for fuel cell applications
Solution Approach 2:
The invention employs porous adsorption materials including activated carbon, zeolites, and metal-organic frameworks (MOFs) that selectively trap sulfur compounds. These porous materials provide high surface area and selective affinity for sulfur, enabling the precise removal of sulfur to ppb levels while preserving the natural gas composition for fuel cell use
3Device complexity
If a single-stage desulfurization process is used, then the process complexity is reduced, but the sulfur removal efficiency is insufficient to achieve ppb range purity
Solution Approach 1:
The invention segments the desulfurization process into multiple sequential adsorption stages, each using different adsorbent materials with complementary sulfur-binding characteristics. This multi-stage approach achieves ppb range sulfur removal efficiency that would be impossible in a single stage, while keeping each individual adsorption unit relatively simple in design
4Manufacturing precision
If adsorbent materials are frequently replaced to maintain desulfurization efficiency, then sulfur removal performance is improved, but continuous operation is interrupted and operational complexity increases
Solution Approach 1:
The invention merges multiple adsorption units into a single integrated desulfurization system where units operate in parallel or sequence. This configuration allows one unit to be regenerated or replaced while others continue operating, maintaining continuous sulfur removal efficiency without interrupting the overall process
Solution Approach 2:
The invention ensures continuous desulfurization operation by designing the adsorption system with multiple units that can be cycled between service and regeneration modes. This allows the useful action of sulfur removal to continue uninterrupted while individual adsorbent materials are periodically regenerated or replaced
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
The method effectively desulfurizes natural gas to a ppb range, enabling its use in fuel cells while minimizing sulfur emissions during combustion, and allows for the reuse of waste gas for purging or heating, ensuring ecological responsibility.
Implementation Method 1
a first pressure swing adsorption apparatus (PSA apparatus) comprising at least one vessel in which an adsorption mass for adsorbing sulphurous material is received
Implementation Method 2
an adsorption mass for adsorbing sulphurous material
Implementation Method 3
a second pressure swing adsorption apparatus (PSA apparatus) comprising at least one vessel in which an adsorption mass for adsorbing carbon monoxide and carbon dioxide is received
Implementation Method 4
an adsorption mass for adsorbing carbon monoxide and carbon dioxide
Implementation Method 5
converting means for converting the second gas mixture into a fourth gas mixture of substantially hydrogen gas and residual gases
Implementation Method 6
a steam reformer which is provided with a burner for supplying heat to this steam reformer
Data Source
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AI summary
Method and device (40, 50) for generating hydrogen gas from a sulphurous first gas mixture comprising at least a hydrocarbon gas, wherein first separating means are provided by a first pressure swing adsorption apparatus (10) for separating the sulphurous first gas mixture into a desulphurized second gas mixture and a sulphurous third gas mixture, wherein converting means are provided for converting the second gas mixture into a fourth gas mixture of substantially hydrogen gas and residual gases, and wherein second separating means are provided by a second pressure swing adsorption apparatus (20) for separating the fourth gas mixture into hydrogen gas and residual gases.