Steam-Hydrocarbon Reforming With Membrane CO2 Capture
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Solution Overview
Problem
Existing steam methane reforming (SMR) processes face inefficiencies in carbon capture due to air-fired combustion generating low-concentration CO2 flue gas, requiring costly and inefficient capture methods, and excess heat management when no steam customers are present.
Innovation Solution
Integrate a reforming process that utilizes a flue gas with reduced CO2 to enhance heat integration, employs a recuperative reformer and membrane separation to capture CO2 at higher concentrations, and recycles hydrogen-depleted retentate streams for additional reforming, reducing fuel requirements and enhancing thermal efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If air-fired combustion is used to generate heat for reforming, then high temperature is achieved, but CO2 concentration in flue gas becomes low making carbon capture costly and inefficient
Solution Approach 1:
The invention extracts nitrogen from the combustion air to create oxygen-enriched air, thereby concentrating the CO2 in the flue gas by removing the inert diluent. This allows high temperature combustion to be maintained while achieving high CO2 concentration in the flue gas for efficient capture.
Solution Approach 2:
The invention changes the composition parameter of the combustion air by removing nitrogen, transforming it from normal air (21% O2, 79% N2) to oxygen-enriched air. This parameter change directly increases the CO2 concentration in the resulting flue gas while maintaining the thermal energy for high-temperature reforming.
2Loss of energy
If excess heat is exported as steam to customers, then thermal efficiency is improved, but in the absence of steam customers the heat must be used internally reducing overall efficiency
Solution Approach 1:
The invention dynamically adjusts heat utilization based on market conditions. When steam customers are available, excess heat is exported as steam. When no customers are present, the system automatically redirects the heat to drive additional reforming reactions to produce more hydrogen and syngas, maximizing value in both scenarios.
Solution Approach 2:
The reforming process is designed to serve multiple functions: it can produce hydrogen and syngas while simultaneously exporting steam to external customers when needed, or using the heat internally to maximize chemical production when no steam customers are available, making the system versatile and adaptable.
3Object-generated harmful factors
If CO2 is captured from flue gas with low concentration, then carbon capture is achieved, but the process becomes costly, inefficient, and bulky
Solution Approach 1:
The invention performs preliminary action by removing nitrogen from the combustion air before combustion occurs. This pre-concentration of oxygen in the combustion air ensures that the resulting flue gas has high CO2 concentration, making subsequent carbon capture much more efficient and less costly.
Solution Approach 2:
The invention changes the compositional parameters of the combustion process by eliminating inert nitrogen, which directly transforms the flue gas from low CO2 concentration to high CO2 concentration, thereby dramatically improving capture efficiency and reducing the scale of capture equipment needed.
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
Achieves nearly 100% CO2 capture with reduced fuel consumption and improved thermal efficiency by utilizing high-concentration CO2 streams for heat exchange and recycling retentate streams, minimizing carbon emissions and optimizing hydrogen production.
Implementation Method 1
The third syngas stream is cooled in a first heat exchanger system which comprises a boiler to produce a first saturated steam stream from a water-containing stream by indirect heat exchange with the third syngas stream
Implementation Method 2
The third syngas stream is cooled in a second heat exchanger system which comprises a steam superheater to heat the first saturated steam stream and produce a superheated steam stream
Implementation Method 3
utilizes a flue gas with reduced CO2 to enhance heat integration
Implementation Method 4
employs a recuperative reformer and membrane separation to capture CO2 at higher concentrations
Data Source
AI summary
A low carbon-emission hydrogen production process may be achieved by first separating carbon dioxide from a reformer syngas stream, followed by separating the carbon dioxide-depleted syngas stream using a semi-permeable membrane to produce a hydrogen-enriched permeate and a hydrogen-depleted retentate. The hydrogen-enriched permeate is purified to produce a hydrogen product and a hydrogen-depleted tail gas stream. The hydrogen-depleted retentate stream may be recycled to the feed and the hydrogen-depleted tail gas stream may be used as fuel in the reformer burners.