Biogas Purification Using Regenerated Alkaline Effluent
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Solution Overview
Problem
Biogas from anaerobic digesters contains high levels of H2S and CO2, which limit its use due to environmental and health hazards, and reduce its energy potential, necessitating effective removal methods to purify it for higher value applications.
Innovation Solution
A novel process using an alkaline effluent, produced through anaerobic digestion and aeration, to selectively remove H2S and subsequently CO2 from biogas, with the effluent being regenerated for repeated use, eliminating the need for chemical absorbents and reducing capital and maintenance costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional chemical absorbents are used to remove H2S and CO2 from biogas, then the contaminants are effectively removed, but capital and maintenance costs increase
Solution Approach 1:
The system uses the digester effluent itself to remove H2S and CO2 from biogas, eliminating the need for external chemical absorbents. The effluent circulates through a contactor where it absorbs contaminants, then regenerates in a stripper unit using steam or heating, and returns to the contactor for repeated use, creating a self-sustaining purification cycle
Solution Approach 2:
The system changes the physical parameters of the effluent by heating it in the stripper unit to regenerate its contaminant-absorbing capacity. This thermal parameter change allows the effluent to release absorbed gases and return to a state where it can effectively remove H2S and CO2 from biogas in subsequent cycles
2Ease of operation
If biogas is used directly without purification, then operational simplicity is maintained, but environmental and health hazards increase due to H2S and CO2
Solution Approach 1:
The system introduces an intermediary substance (the effluent circulating through the contactor) that facilitates the removal of harmful contaminants from biogas. This intermediary absorbs H2S and CO2 through chemical reactions, allowing the biogas to be purified without complex purification equipment or multiple processing steps
3Use of energy by moving object
If H2S and CO2 are not removed from biogas, then energy input is minimized, but energy potential is reduced due to inert CO2 and corrosive H2S
Solution Approach 1:
The system achieves multiple functions using the same effluent stream: it removes H2S to prevent corrosion and improve safety, removes CO2 to increase energy content, and regenerates itself for continuous operation. This multi-functionality maximizes the value extracted from the effluent while minimizing additional energy input requirements
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 effectively reduces H2S and CO2 concentrations, enhancing the energy potential of biogas, making it suitable for wider energy applications while minimizing environmental impact and operational costs.
Implementation Method 1
contacting the heated and aerated effluent with the biogas to remove H2S
Implementation Method 2
an alkaline effluent, produced through anaerobic digestion and aeration, to selectively remove H2S and subsequently CO2 from biogas
Implementation Method 3
contacting the regenerated effluent with the biogas to remove CO2
Implementation Method 4
an alkaline effluent, produced through anaerobic digestion and aeration, to selectively remove H2S and subsequently CO2 from biogas
Implementation Method 5
heated and aerated effluent from an anaerobic digester
Data Source
AI summary
Methods, systems and apparatuses herein provide a unique and novel process to remove H2S from biogas. Methods, systems and apparatuses herein provide a unique and novel process to remove H2S from biogas with ease of operation and reduced operating and capital costs. Methods, systems and apparatuses herein provide a unique and novel process to remove H2S over CO2 from biogas.