CO2 PSA Membrane Integration for Steam Reforming Recovery
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Solution Overview
Problem
Current processes for recovering high purity carbon dioxide from waste gas streams in steam hydrocarbon reforming units are energy-intensive and costly, particularly in small-scale operations, and fail to efficiently utilize waste streams that typically end up as makeup fuel.
Innovation Solution
Integration of a CO2 pressure swing adsorption (PSA) or CO2 pressure vacuum swing adsorption (PVSA) unit with a membrane separation unit within the steam hydrocarbon reforming, water gas shift, and hydrogen pressure swing adsorption processes to recover high purity CO2 from waste gas streams, allowing for the reuse of CO2 as a valuable product rather than fuel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If generic physical or chemical solvents are used for CO2 recovery, then high purity CO2 can be recovered, but equipment costs and regeneration energy requirements increase significantly
Solution Approach 1:
The patent changes the operating parameters of the PSA unit (pressure cycles, flow rates, temperature) to optimize CO2 recovery efficiency. By adjusting these parameters, the system achieves high purity CO2 recovery while minimizing energy consumption compared to conventional solvent-based methods
Solution Approach 2:
The patent replaces chemical solvent-based separation with a mechanical pressure swing adsorption process. This substitution eliminates the need for chemical regeneration and associated energy requirements, while maintaining high CO2 purity through physical adsorption on solid adsorbent materials
2Quantity of substance
If CO2 CPU process is used in small size CO2 recovery plants, then CO2 can be captured, but energy and maintenance costs become unacceptably high
Solution Approach 1:
The patent employs dynamic pressure cycling in the PSA unit, alternating between high-pressure adsorption and low-pressure desorption phases. This dynamic operation allows the system to adapt to varying feed gas compositions and flow rates, optimizing CO2 capture efficiency while maintaining low energy consumption suitable for small-scale operations
Solution Approach 2:
The PSA process uses periodic pressure changes to alternately load and unload CO2 from the adsorbent beds. This periodic action enables continuous CO2 recovery with minimal energy input, as the pressure swings are achieved through simple valve operations rather than continuous compression or cryogenic cooling
3Loss of energy
If waste gas streams from H2 PSA are burned as make up fuel, then energy balance is maintained, but CO2 recovery and utilization opportunities are lost
Solution Approach 1:
The patent introduces a CO2 PSA unit as an intermediary between the H2 PSA waste gas stream and potential CO2 utilization processes. This intermediary selectively separates CO2 from the waste stream, allowing the remaining gas to be used as fuel while recovering CO2 for valuable applications, thus eliminating the need to choose between energy balance and CO2 recovery
4Manufacturing precision
If two stage CO2 VSA/PSA process is used to produce food grade CO2, then high purity CO2 is achieved, but another CO2 lean product is generated that must be sent to reformer as fuel
Solution Approach 1:
The patent designs the CO2 PSA system to perform multiple functions: producing food-grade CO2 in one stream while simultaneously generating a CO2-lean fuel gas in another stream. Both products are valuable - the pure CO2 for commercial sale and the fuel gas for plant energy needs - thus the single process delivers dual productivity without requiring a second reformer 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 integrated process enables efficient recovery of high purity CO2 from both high and low concentration mixtures, reducing energy costs and enhancing hydrogen recovery, while providing a flexible and reliable operation suitable for both small and large-scale merchant CO2 markets.
Implementation Method 1
a CO2 pressure swing adsorption (PSA) or CO2 pressure vacuum swing adsorption (PVSA) unit
Implementation Method 2
membrane separation unit
Data Source
Figure 1
Figure 2
AI summary
The present invention provides for various processes for recovering high purity gaseous hydrogen and high purity gaseous carbon dioxide from the gas stream produced using steam hydrocarbon reforming, especially steam methane reforming, utilizing a H2 pressure swing adsorption unit in combination with either a CO2 pressure swing adsorption unit in combination with a membrane separation unit or a CO2 pressure vacuum swing adsorption unit in combination with a membrane separation unit. The present invention further relates to a process for optimizing the recovery of carbon dioxide from waste gas streams produced during the hydrogen purification step of a steam hydrocarbon reforming /water gas shift reactor /H2 pressure swing adsorption unit utilizing either a CO2 pressure swing adsorption unit in combination with a membrane separation unit or a CO2 pressure vacuum swing adsorption unit in combination with a membrane separation unit. The present invention even further relates to the apparatus necessary to carry out the various processes of the present invention.