Biomethane Production via Impurity Solidification and CO2 Separation
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Solution Overview
Problem
Current methods for purifying biogas to produce biomethane are limited by the presence of impurities like ammonia, volatile organic compounds, water, sulfur-based impurities, and siloxanes, which affect the calorific value and economic viability of biogas for broader use, including injection into natural gas networks.
Innovation Solution
A process involving drying, partial removal of impurities through compression and solidification, and subsequent separation of methane and carbon dioxide using a cyclic method involving cooling and sublimation, with CO2 flushing, to produce a high-purity biomethane stream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If biogas is used near the production site with light treatment, then it can supply heat and electricity locally, but the high carbon dioxide content reduces its calorific value and increases compression and transport costs
Solution Approach 1:
The patent segments the purification process into distinct stages: drying, impurity removal through solidification, and CO2 separation. This segmentation allows each stage to address specific impurities efficiently, thereby maximizing calorific value recovery while maintaining local energy supply benefits.
Solution Approach 2:
The patent employs parameter changes by controlling temperature and pressure conditions to selectively remove different impurities. By adjusting these parameters, the process optimizes calorific value recovery while enabling local energy utilization.
2Adaptability or versatility
If biogas is extensively purified to natural gas specifications to produce biomethane, then it can be injected into natural gas networks and used broadly, but multiple treatment steps are required before CO2 separation
Solution Approach 1:
The patent applies preliminary action by performing drying and impurity removal through solidification before the main CO2 separation step. This preliminary treatment simplifies the subsequent CO2 separation process and enables biomethane production suitable for network injection.
Solution Approach 2:
The patent utilizes phase transitions, specifically the solidification of impurities at controlled temperatures, to remove them from the biogas stream before CO2 separation. This approach simplifies the overall purification process while achieving the required biomethane quality.
3Loss of energy
If impurities are removed from biogas, then the calorific value increases and economic viability improves, but the presence of ammonia, volatile organic compounds, water, sulfur-based impurities, and siloxanes affects the purification process
Solution Approach 1:
The patent applies local quality by targeting specific impurities (ammonia, volatile organic compounds, water, sulfur-based impurities, and siloxanes) with specialized treatment methods. Each impurity type is addressed through controlled solidification at specific temperature ranges, effectively removing them while maximizing calorific value.
Solution Approach 2:
The patent utilizes phase transitions by cooling the biogas to specific temperatures where different impurities solidify at different rates. This allows selective removal of various impurity types through controlled freezing and filtration, thereby increasing calorific value while managing the complexity of multiple impurity types.
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 removes impurities, enhancing the calorific value and economic viability of biogas, allowing it to meet natural gas specifications for broader utilization, including injection into gas networks and storage as liquefied natural gas.
Implementation Method 1
a second step of at least partial removal of said impurity contained in the dried biogas stream by solidification and removal of the impurity
Implementation Method 2
a third step of separating the methane and the carbon dioxide contained in the biogas obtained from the second step
Data Source
AI summary
Process for producing biomethane from a biogas stream including methane, carbon dioxide and at least one impurity chosen from ammonia, volatile organic compounds, water, sulfur-based impurities (H2S) and siloxanes. A biogas stream is dried, the at least one impurity is at least partially removed by solidification and removal of the impurity. The methane and the carbon dioxide contained in the biogas obtained from the second step are separated so as to produce a biomethane stream and a CO2 stream.