Biogas Methane Purification via Physical NMOC Separation
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Solution Overview
Problem
Conventional methods for isolating and purifying methane from biogas result in the thermal destruction of non-methane organic compounds (NMOC), leading to the production of carbon dioxide, a greenhouse gas, which contributes to global warming.
Innovation Solution
A system and method that separates biogas into methane and NMOC streams using a liquid sulfur scrubber or sulfur adsorber, followed by NMOC absorption and adsorption units, and a CO2, N2, O2 gas separation unit, avoiding thermal destruction and subsequent greenhouse gas emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional thermal destruction is used to remove NMOC from biogas, then methane purification is achieved, but carbon dioxide is produced as a greenhouse gas
Solution Approach 1:
The patent extracts NMOC from biogas through physical separation methods (absorption, adsorption, condensation) rather than thermal destruction. This takes out the harmful component without producing CO2, resolving the contradiction between purification and greenhouse gas emissions.
Solution Approach 2:
The patent changes the removal mechanism from thermal (combustion) to physical/chemical (absorption, adsorption, condensation) by altering process parameters. This allows NMOC removal without carbon dioxide generation while maintaining methane purification.
2Object-generated harmful factors
If multiple separation units are added to avoid thermal destruction, then greenhouse gas emissions are reduced, but system complexity increases
Solution Approach 1:
The patent segments the NMOC removal process into multiple distinct units (absorber, adsorber, condenser) that can be configured in series or parallel. This segmentation allows flexible system design that reduces greenhouse gas emissions while managing complexity through modular architecture.
Solution Approach 2:
The patent designs separation units that can handle multiple components (NMOC, H2S, CO2) simultaneously or sequentially. This multi-functionality reduces the need for separate specialized equipment, thereby managing system complexity while achieving comprehensive pollutant removal.
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
The system effectively separates and purifies methane while collecting and removing NMOC, significantly reducing greenhouse gas emissions and producing a methane stream suitable for use as natural gas, with a greater than 98% reduction in NMOC emissions.
Implementation Method 1
The Biogas stream is fed into the intake of a liquid sulfur scrubber or a sulfur adsorber unit, where the Biogas is separated into a main gas stream routed downstream in the system and a sulfur compounds stream
Implementation Method 2
The Biogas stream is fed into the intake of a liquid sulfur scrubber or a sulfur adsorber unit, where the Biogas is separated into a main gas stream routed downstream in the system and a sulfur compounds stream
Implementation Method 3
The main gas stream is then processed by an NMOC absorber
Implementation Method 4
further downstream, by an NMOC adsorber
Implementation Method 5
an off-gas stream in which a vent pressure swing adsorption unit (VPSAU) processes the off-gas for venting and recycling
Data Source
Figure 1
AI summary
The method and system for methane separation and purification from a biogas includes collecting a raw Biogas gas stream (2) having methane, carbon dioxide, water, sulfur compounds and non-methane organic compound (NMOC) constituents. The Biogas stream (2) feeds into the intake of a liquid sulfur scrubber or a sulfur adsorber unit (3) where the Biogas is separated into a main gas stream (16) routed downstream in the system and a sulfur compounds stream (4) removed from the system. The main gas stream (16) is then processed by an NMOC absorber (7) and further downstream, by an NMOC adsorber (12). NMOC produced by both NMOC processes is liquefied, removed from the system and stored. Upstream from the NMOC processes, the main gas stream is processed by at least one CO2, N2, O2 gas separation unit (16) that produces a usable product stream (17) of enriched methane gas, and an off-gas stream (19), which a VPSAU (20) processes for venting and recycling.