Hydrate-Based CO2 Capture in Hydrogen Production
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Solution Overview
Problem
Current hydrogen production methods, such as Steam Methane Reforming (SMR), fail to achieve complete CO2 capture due to incomplete methane conversion and subsequent CO2 emission during methane combustion, limiting CO2 capture rates to around 75-80%.
Innovation Solution
A process involving steam reforming of hydrocarbon feedstocks to produce synthesis gas, followed by conversion and capture of CO2 and methane as hydrates, with subsequent regeneration and recycling of methane back into the reforming stage, allowing for nearly complete CO2 capture and efficient hydrogen production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If steam reforming is used to produce hydrogen, then hydrogen production efficiency is improved, but CO2 capture completeness deteriorates due to incomplete methane conversion
Solution Approach 1:
The patent recovers unconverted methane from the hydrogen stream and returns it to the steam reforming unit for complete conversion. This closing loop ensures that methane which would otherwise be discarded or combusted is instead recovered and processed, achieving complete CO2 capture while maintaining high hydrogen production efficiency.
Solution Approach 2:
The patent implements a feedback mechanism where the hydrogen stream is analyzed to detect unconverted methane, and this information is used to adjust the process conditions and recycle methane back to the reforming unit. This continuous feedback loop ensures complete conversion and capture of CO2 while maintaining optimal hydrogen production.
2Manufacturing precision
If PSA unit is added to separate methane, then hydrogen purity is improved, but energy consumption increases due to recompression requirements
Solution Approach 1:
The patent changes the approach from pressure-based separation (PSA) to temperature-based separation using hydrate formation. By controlling temperature and pressure conditions, methane forms hydrates that can be separated from hydrogen, achieving high purity without requiring energy-intensive recompression of the methane stream.
Solution Approach 2:
The patent replaces the mechanical PSA separation system with a chemical/physical hydrate-based separation system. This substitution eliminates the need for complex pressure swing operations and recompression equipment, significantly reducing energy consumption while achieving comparable or superior hydrogen purity.
3Reliability
If amine washing is used to capture CO2, then CO2 capture rate is improved, but methane loss increases due to incomplete separation
Solution Approach 1:
The patent segments the separation process into distinct stages: first separating CO2 from the gas stream using amine washing, then separately addressing methane removal through hydrate formation. This segmentation allows each component to be optimized independently, achieving complete CO2 capture while preventing methane loss in the CO2 capture 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 process achieves nearly complete CO2 capture and methane recycling without energy loss, enhancing hydrogen purity and reducing CO2 emissions during methane combustion, thereby improving the efficiency and environmental impact of hydrogen production.
Implementation Method 1
a step of producing a synthesis gas in a steam reforming unit of the hydrocarbon feed in the presence of water vapor
Implementation Method 2
a step of converting the synthesis gas obtained to steam in the previous step producing a stream of hydrogen containing methane and carbon dioxide
Implementation Method 3
a step of capturing the carbon dioxide and methane, present in the stream obtained in the steam conversion step, in the form of hydrates producing a flow of pure hydrogen
Implementation Method 4
a methane regeneration step
Data Source
Figure 1~2
Figure 3~4
AI summary
Preparing hydrogen from a hydrocarbon charge and steam, comprises: (a) producing synthesis gas in a unit for steam reforming of the hydrocarbon charge in the presence of steam, a fuel providing heat to the reaction; (b) converting synthesis gas in steam for producing a hydrogen stream containing methane and carbon dioxide; (c) capturing carbon dioxide and methane, present in the stream obtained in conversion step, in the form of hydrates producing a stream of pure hydrogen; (d) regenerating the methane; and (e) recycling the methane towards steam reforming.