Hydrogen PSA with Dual-Stream CO₂ Recovery to Reduce Purge Loss
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Solution Overview
Problem
Current hydrogen production processes face challenges in achieving cost-effective CO2 recovery, with existing methods often requiring complex and costly configurations, such as high-pressure co-purge streams and segmented adsorber vessels, which increase operational complexity and expenses.
Innovation Solution
The implementation of a Pressure Swing Adsorption (PSA) system that produces at least two product streams, integrated with a CO2 recovery system, allows for the recovery of high-purity hydrogen and CO2, eliminating the need for high-pressure co-purge streams and segmented vessels, thereby simplifying and reducing the cost of the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If conventional PSA processes are used with single product stream, then CO2 recovery is achieved, but additional hydrogen is lost in purge streams and process complexity increases
Solution Approach 1:
The PSA system is segmented into multiple adsorbers that operate in different modes (production, purge, repressurization) simultaneously, allowing the purge stream from one adsorber to be used as repressurization gas for another adsorber, thereby recovering hydrogen that would otherwise be lost
Solution Approach 2:
The patent merges the purge function and repressurization function into a single integrated stream, where the purge gas from one adsorber is directly used to repressurize another adsorber, eliminating the need for separate high-pressure CO2 make-up gas and reducing hydrogen losses
2Manufacturing precision
If high-pressure co-purge streams and segmented adsorber vessels are used, then CO2 separation is improved, but device complexity and operational costs increase
Solution Approach 1:
The PSA system is designed so that each adsorber can perform multiple functions at different times (hydrogen production, CO2 purge, repressurization), and the purge stream serves dual purposes of purging CO2 and repressurizing other beds, reducing the need for additional equipment
Solution Approach 2:
Instead of discarding the purge stream containing hydrogen and CO2, the system recovers and utilizes this stream to repressurize other adsorbers, converting what would be waste into a useful resource and simplifying the need for external high-pressure gas supplies
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 enhances process economics by recovering additional hydrogen, reducing downstream equipment size and utilities, and increasing CO2 capture efficiency, while avoiding non-permeate losses associated with membrane separation.
Implementation Method 1
separating an effluent stream comprising the synthesis gas from the hydrogen production process unit in a hydrogen pressure swing adsorption (PSA) unit into a first high-pressure hydrogen stream enriched in hydrogen and a hydrogen depleted tail gas stream
Data Source
AI summary
A process and apparatus for producing a hydrogen-enriched product and recovering CO2 from an effluent stream from a hydrogen production process unit are described. The process utilizes a CO2 recovery system integrated with a PSA system that produces at least two product streams to recover additional hydrogen and CO2 from the tail gas stream of a hydrogen PSA unit in the hydrogen production process.