Facility and method for producing biomethane with limited methane loss and limited co2 emissions
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Solution Overview
Problem
Existing biogas purification methods struggle to produce biomethane at a constant concentration while minimizing methane loss and carbon dioxide emissions, particularly in the separation of methane and carbon dioxide.
Innovation Solution
An installation and method utilizing multiple membrane separation units, compression, cooling, and distillation to recycle methane-rich streams, with feedback control for adjusting pressure and temperature to maintain methane concentration, and a distillation column for separating gas and liquid streams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If membrane separation is used to remove CO2 from biogas, then CO2 content is reduced, but methane loss occurs in the waste gas stream
Solution Approach 1:
The patent recovers methane from the waste gas stream by condensing it at low temperatures and pressures between 1-5 bar. The condenser recovers methane that would otherwise be lost, converting it to liquid form for return to the process. This resolves the contradiction by recovering the valuable substance (methane) that would normally be discarded with the CO2-rich waste stream.
Solution Approach 2:
The patent changes the pressure parameter of the permeate stream from typical high pressure (17-25 bar) to low pressure (1-5 bar) before condensation. This parameter change optimizes the condensation process for methane recovery while minimizing energy consumption and maximizing methane retrieval from the waste stream.
2Manufacturing precision
If compression is applied to biogas before membrane treatment, then separation efficiency improves, but energy consumption increases
Solution Approach 1:
The patent changes the pressure parameter from high compression (17-25 bar) to low pressure (1-5 bar) for the condensation step. This parameter change reduces energy consumption while maintaining effective methane recovery through optimized condensation conditions at lower pressures.
3Manufacturing precision
If multiple membrane stages are used to achieve high methane purity, then biomethane quality improves, but device complexity increases
Solution Approach 1:
Instead of adding more membrane stages, the patent recovers methane from the waste stream of existing membrane stages through condensation. This approach achieves high overall methane recovery without increasing membrane system complexity, as it utilizes the existing separation infrastructure more efficiently.
4Productivity
If permeate is compressed to high pressure for condensation, then methane recovery efficiency improves, but compression costs increase
Solution Approach 1:
The patent changes the compression pressure from high (17-25 bar) to low (1-5 bar) for the permeate stream before condensation. This parameter change reduces compression energy costs while maintaining effective methane recovery through optimized condensation conditions at lower pressures.
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 solution ensures the production of biomethane at a consistent concentration with minimal methane loss and reduces carbon dioxide emissions, achieving high methane purity and cost-effectiveness.
Implementation Method 1
installation for the treatment by membrane permeation of a feed gas stream comprising at least methane and carbon dioxide
Implementation Method 2
a compressor for compressing the first permeate to a pressure of between 17 bar and 25 bar
Implementation Method 3
a means for cooling the compressed first permeate to a temperature below -40°C
Implementation Method 4
a distillation column for separating the cooled first permeate into a gas stream and a liquid stream
Data Source
AI summary
Disclosed are a facility and a method using the facility for treating a feed gas stream comprising at least methane and carbon dioxide by membrane permeation, the facility comprising: - a first membrane separation unit capable of receiving the feed gas stream and providing a first permeate and a first retentate, - a second membrane separation unit capable of receiving the first retentate and providing a second permeate and a second retentate, - a compressor for compressing the first permeate to a pressure of between 17 bar and 25 bar, - a means for cooling the first compressed permeate to a temperature lower than -40°C, - a distillation column for separating the first cooled permeate into a gas stream and a liquid stream, - at least one means for recycling the gas stream exiting the distillation column to the inlet of the first membrane separation unit, - a means for measuring the concentration of methane and/or carbon dioxide in the gas stream exiting the distillation column, - a means for comparing the concentration of methane and/or carbon dioxide measured by the measurement means with a target value, and - a means for adjusting the pressure and/or the temperature of the first permeate depending on the comparison carried out by the comparison means.