Sour Pressure Swing Adsorption for Syngas Purification
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Solution Overview
Problem
Current syngas processing methods are costly and energy-intensive due to the need for multiple purification steps, such as acid gas removal and nitrogen wash operations, to remove impurities like CO2 and H2S from sour syngas, which are essential for producing high-purity H2 for applications like ammonia or methanol production.
Innovation Solution
Implementing a sour pressure swing adsorption (SPSA) process with a rinse step to recover H2 and CO, followed by an acid gas enrichment (AGE) process to separate and remove sulfur-containing species, thereby reducing the need for downstream purification steps and enhancing the recovery of desired products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If acid gas removal (AGR) by absorption and nitrogen wash operations are used to remove CO2 and H2S from sour syngas, then the purity of H2 product is improved, but the capital cost and operating cost increase significantly
Solution Approach 1:
The patent combines multiple purification functions (CO2 removal, H2S removal, and H2 purification) into a single pressure swing adsorption (PSA) system. The PSA unit integrates the roles of traditional AGR units and nitrogen wash operations, achieving all separations in one device rather than requiring separate sequential units for each impurity removal step.
Solution Approach 2:
The PSA system performs multiple functions simultaneously: it removes CO2, removes H2S, and purifies H2 in a single process unit. The adsorbent beds in the PSA system are designed to handle multiple impurities and produce high-purity H2 product, making the system universal rather than requiring specialized units for each separation task.
2Manufacturing precision
If multiple purification steps (AGR and nitrogen wash) are implemented to remove impurities, then the quality of H2 product is improved, but the power consumption increases
Solution Approach 1:
The PSA system operates on periodic cycles of adsorption and desorption. During the adsorption phase, impurities are removed from the syngas stream. During the desorption phase, the adsorbent is regenerated by reducing pressure and purging accumulated impurities. This periodic operation allows continuous purification without requiring continuous high-energy input, reducing overall power consumption compared to continuous AGR and nitrogen wash operations.
Solution Approach 2:
The PSA system uses its own product stream (high-purity H2) to purge and regenerate the adsorbent beds during the desorption phase. This self-service mechanism eliminates the need for external high-energy purification steps like nitrogen wash, as the system recycles its own output to maintain the adsorbent's cleaning function.
3Manufacturing precision
If traditional AGR processes are used with liquid solvents, then CO2 and H2S are removed from syngas, but the process requires significant capital investment and operating costs
Solution Approach 1:
The patent replaces the liquid solvent absorption mechanism (chemical AGR process) with a solid adsorbent-based pressure swing adsorption system. Instead of using liquid solvents like Selexol or Rectisol that require complex regeneration systems and heat exchangers, the PSA system uses solid adsorbent materials that selectively adsorb CO2 and H2S under pressure and are regenerated by pressure reduction, simplifying the overall process infrastructure.
Solution Approach 2:
The PSA system employs porous adsorbent materials with specific pore structures and surface chemistries that selectively capture CO2 and H2S molecules from the syngas stream. These porous materials provide high surface area for impurity adsorption and can be tuned for selective separation, replacing the need for liquid solvent systems and their associated capital-intensive equipment.
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 significantly reduces the overall costs and energy consumption of syngas processing while achieving high recovery of H2 and CO, producing a high-quality gas stream suitable for ammonia or methanol synthesis without the need for additional purification steps.
Implementation Method 1
introducing the sour syngas stream into a sour pressure swing adsorption (SPSA) system having a plurality of adsorber beds; performing a cyclic PSA process using the PSA system
Implementation Method 2
pressurizing a first bed of the plurality of adsorber beds to a first pressure; feeding the sour syngas stream into an inlet end of the pressurized first bed and discharging a first gas stream from an outlet end of the first bed
Implementation Method 3
converting at least a portion of the CO in the gasified stream to CO2 and H2 using a water-gas shift reaction
Data Source
AI summary
Methods and apparatuses for separating CO2 and sulfur-containing compounds from a synthesis gas obtained from gasification of a carbonaceous feedstock. The primary separating steps are performed using a sour pressure swing adsorption (SPSA) system, followed by an acid gas enrichment system and a sulfur removal unit. The SPSA system includes multiple pressure equalization steps and a rinse step using a rinse gas that is supplied from a source other than directly from one of the adsorber beds of the SPSA system.