Hydrogen Purge Gas Fermentation for Heat Integration
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Solution Overview
Problem
The inefficiency in utilizing hydrogen in purge gas streams during hydrogen production processes, where hydrogen is costly and its combustion for heat production reduces the economic viability of the process, necessitates a better utilization of the purge gas components without disrupting the hydrogen production process.
Innovation Solution
A process that ferments the purge gas stream from hydrogen production using microorganisms in bioreactors to produce a fermentation product, such as ethanol, while utilizing the fermentation exhaust gas and additional fuel gas, like methane, to provide heat for the reforming unit, thereby maximizing energy value and reducing hydrogen combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If hydrogen in purge gas stream is combusted to provide process heat, then heat integration is achieved and high temperature requirements for reforming are met, but hydrogen is wasted and process economics deteriorate
Solution Approach 1:
The patent converts the previously harmful waste hydrogen in purge streams into a beneficial resource by introducing it to anaerobic digesters. The hydrogen is consumed in microbial fermentation to produce methane and carbon dioxide, transforming the energy loss into useful biogas product while eliminating the need to burn hydrogen for heat.
Solution Approach 2:
The patent introduces anaerobic digesters as an intermediary system between the hydrogen production process and the heat generation system. Instead of directly burning hydrogen, the system uses microbial fermentation as an intermediate conversion process to transform hydrogen into biogas, which can then be used for heat production or other purposes.
2Quantity of substance
If hydrogen is recovered from purge gas stream using pressure swing adsorption, then hydrogen concentration is increased for valuable product, but additional equipment complexity and operational disruption are required
Solution Approach 1:
The patent extracts the hydrogen recovery function from the complex pressure swing adsorption system and replaces it with a simpler biological consumption approach. Instead of extracting and concentrating hydrogen for product, the system extracts the energy value of hydrogen by using it as substrate for anaerobic fermentation, eliminating the need for complex separation equipment.
Solution Approach 2:
The patent replaces expensive, complex PSA equipment with a simpler, more flexible biological system. The anaerobic digesters use readily available microbial populations that consume hydrogen without requiring sophisticated separation technology, effectively replacing capital-intensive equipment with lower-cost biological processes.
3Ease of operation
If purge gas stream is vented or burned, then process simplicity is maintained, but valuable hydrogen energy is lost and environmental impact increases
Solution Approach 1:
The patent makes the purge gas stream multi-functional by introducing it to anaerobic digesters where it serves dual purposes: (1) consuming the valuable hydrogen energy that would otherwise be lost, and (2) producing biogas (methane and carbon dioxide) that can be used as a fuel source or environmental byproduct. This transforms a waste stream into a resource stream.
Solution Approach 2:
The system enables self-service by using the purge gas stream itself as the fuel source for the anaerobic fermentation process. The hydrogen in the purge stream provides the energy needed to drive the microbial metabolism, creating a self-sustaining system where the waste product fuels the conversion process without requiring external energy 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 approach enhances the efficiency of hydrogen production by converting hydrogen into a higher value fermentation product, reduces the need for hydrogen combustion, and improves process economics by using low-cost methane for heat generation, while maintaining heat integration within the hydrogen production process.
Implementation Method 1
a purge stream from hydrogen production is fermented in one or more bioreactors by microorganisms to produce the fermentation product
Implementation Method 2
process energy in the form of heat is provided to a reforming unit of a hydrogen production process by a fermentation exhaust gas stream obtained from one or more bioreactors
Data Source
AI summary
The present invention provides an integrated process for producing a fermentation product from fossil carbon and hydrogen present in a purge gas stream resulting from a hydrogen production process. According to the invention, a purge gas stream obtained from a hydrogen production process is fermented with microorganisms in one or more bioreactors to produce the fermentation product. A fermentation exhaust gas stream from the one or more bioreactors comprising hydrogen, carbon monoxide and/or methane is then obtained and heat is generated therefrom to provide energy for a reforming unit that forms part of the hydrogen production process.