Hydrogen Production via Physical Absorption and Flash Regeneration
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Solution Overview
Problem
Current methods for producing hydrogen and separating carbon dioxide from synthesis gas are energy-intensive and require complex apparatus, particularly due to the need for liquefaction of carbon dioxide, which is costly and inefficient.
Innovation Solution
A process involving physical absorption of carbon dioxide using a medium cooled and operated at elevated pressure, followed by flash stages for regeneration, which allows for efficient separation of carbon dioxide without the need for liquefaction, thereby reducing energy requirements and apparatus complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If chemical absorption with amine solvents is used to separate carbon dioxide, then carbon dioxide separation is achieved, but high energy requirements are needed to regenerate the solvent
Solution Approach 1:
The invention changes the fundamental parameters of the absorption process by using physical absorption instead of chemical absorption, operating at lower temperatures and utilizing pressure differential for regeneration rather than thermal regeneration. This parameter change eliminates the energy-intensive solvent regeneration step while maintaining effective carbon dioxide separation.
Solution Approach 2:
The invention replaces the thermal/chemical regeneration mechanism with a mechanical pressure-based regeneration system. By using pressure reduction and flashing instead of heat input for solvent regeneration, the process substitutes a low-energy mechanical approach for a high-energy thermal process.
2Measurement precision
If carbon dioxide is separated by condensation and compression to the triple point, then high purity carbon dioxide is obtained, but complex apparatus and high energy requirements are needed
Solution Approach 1:
The invention extracts carbon dioxide from the synthesis gas stream using physical absorption at ambient or near-ambient conditions, removing the need for complex cryogenic condensation equipment. The absorption medium selectively takes out carbon dioxide without requiring the synthesis gas to be cooled to triple point conditions.
Solution Approach 2:
The invention replaces the complex thermal-mechanical cryogenic system with a simpler physical absorption system operating at near-ambient temperatures. The regeneration is achieved through simple pressure reduction and flashing rather than complex compression and cooling cycles.
3Use of energy by moving object
If physical absorption is used to separate carbon dioxide, then energy requirements are reduced, but co-absorption of hydrogen and carbon monoxide occurs
Solution Approach 1:
The invention optimizes operating parameters including temperature, pressure, and absorption medium selection to enhance carbon dioxide selectivity. By carefully controlling these parameters, the process maximizes carbon dioxide absorption while minimizing co-absorption of hydrogen and carbon monoxide.
Solution Approach 2:
The invention employs multiple absorption stages with different local conditions (temperature, pressure, absorption medium composition) to selectively absorb carbon dioxide at each stage. The counter-current flow arrangement creates optimal local conditions for carbon dioxide absorption while allowing selective stripping of co-absorbed gases in subsequent stages.
4Productivity
If synthesis gas is cooled for physical absorption, then carbon dioxide absorption efficiency is improved, but additional cooling energy is required
Solution Approach 1:
The invention merges the cooling function with the carbon dioxide absorption function by using the same cooling infrastructure for both purposes. The cooling required for physical absorption is integrated with the existing synthesis gas cooling requirements, eliminating duplicate cooling systems and optimizing energy utilization.
Solution Approach 2:
The absorption process itself contributes to the cooling requirement by utilizing the temperature difference between the synthesis gas and the absorption medium. The system is designed to self-regulate temperature conditions, reducing the need for additional active cooling input.
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 maximizes hydrogen yield and achieves high-purity carbon dioxide separation with reduced energy consumption and operational costs, eliminating the need for energy-intensive liquefaction and complex apparatus.
Implementation Method 1
removing carbon dioxide from the cooled synthesis gas via the cooled absorption medium in a physical absorption step at elevated pressure
Implementation Method 2
treating the laden absorption medium in a plurality of serially arranged flash stages, wherein co-absorbed carbon monoxide and hydrogen is removed from the laden absorption medium in at least one first flash stage and carbon dioxide is removed from the laden absorption medium in a flash stage arranged downstream of the first flash stage
Data Source
AI summary
The present invention relates to a process for producing hydrogen and for separating carbon dioxide from synthesis gas using a physical absorption medium. The process comprises the steps where the synthesis gas and the absorption medium are cooled; carbon dioxide is removed from the cooled synthesis gas via the cooled absorption medium in a physical absorption step at elevated pressure; laden absorption medium is treated in a plurality of flash stages, wherein co-absorbed carbon monoxide, hydrogen and carbon dioxide are separately removed from the laden absorption medium; hydrogen is separated from synthesis gas freed of carbon dioxide in a physical separation step, wherein hydrogen as product gas and an offgas comprising hydrogen, carbon monoxide and carbon dioxide are obtained; product gas hydrogen and carbon dioxide are discharged from the process. The invention further relates to a plant for performing the process.