Membrane Separation for Lean Gas Methane Reduction
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Solution Overview
Problem
Lean gases with low methane content pose challenges for direct use in conventional gas engines or burners and require costly and complex processes to comply with emission regulations, as they are difficult to combust and release due to high methane concentrations contributing to greenhouse effects.
Innovation Solution
A method involving membrane separation to reduce CO2 and exchange gas proportions with O2, followed by recycling and post-oxidation of the permeate in a hot exhaust gas stream, ensuring methane levels comply with legal limits and enabling stable operation of conventional utilization units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If low-calorific gas is directly combusted in conventional burners or gas engines, then the combustion process is simple and cost-effective, but the low methane content (below 17.5% by volume) prevents stable self-sustaining oxidation
Solution Approach 1:
The patent introduces an intermediary substance (auxiliary fuel such as natural gas, biogas, or LPG) that mediates between the low-calorific gas and the combustion process. This auxiliary fuel raises the methane concentration in the burner to at least 17.5% by volume, enabling stable combustion without requiring complex modifications to the burner or engine system.
2Device complexity
If low-calorific gas is released into the atmosphere without treatment, then no combustion infrastructure is needed, but methane emissions contribute significantly to the greenhouse effect
Solution Approach 1:
The patent converts the harmful methane emissions into a beneficial combustion process. By using the low-calorific gas as fuel in burners or gas engines (with the addition of auxiliary fuel), the methane that would otherwise be released into the atmosphere is instead combusted to generate thermal energy or electricity, thus eliminating greenhouse gas emissions while producing useful energy.
3Reliability
If auxiliary fuel is added to enable combustion of low-calorific gas, then stable combustion is achieved, but operational costs and system complexity increase
Solution Approach 1:
The patent changes the compositional parameter of the gas mixture by adding auxiliary fuel to raise the methane concentration to at least 17.5% by volume. This parameter change enables the use of conventional burners and gas engines without requiring expensive modifications to the combustion infrastructure or control systems.
4Adaptability or versatility
If membrane separation is used to concentrate methane in low-calorific gas, then the gas can be used in conventional engines, but the process complexity and cost increase
Solution Approach 1:
Instead of using complex membrane separation processes to concentrate methane, the patent applies a simpler partial action approach by adding just enough auxiliary fuel to raise the methane concentration to the minimum required level (17.5% by volume) for conventional engine operation. This avoids the need for expensive and complex separation infrastructure.
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 method allows for the efficient and cost-effective operation of gas engines and burners across a broader methane concentration range, ensuring compliance with emission regulations by reducing methane levels in the permeate to below 0.2% volume, thus allowing safe atmospheric release.
Implementation Method 1
separation in a membrane unit (5), wherein the retentate (4) is connected to a utilization unit (6-9, 15)
Implementation Method 2
The combustible gases (usually methane or other gaseous hydrocarbons, such as hydrogen and/or carbon monoxide) are so diluted in low-calorific gases with non-combustible components
Data Source
Figure 1
AI summary
The method involves reducing a carbon dioxide-portion in lean gas and/or exchanging gas portions in the lean gas against oxygen in a membrane separation unit (1). A retentate is subsequently utilized in an utilization unit, which is provided downstream to the membrane separation unit on a retentate side. A permeate of the membrane separation unit is mixed to hot exhaust gas of the utilization unit, and reoxidized. A partial pressure difference between the permeate and the retentate in the membrane separation unit is increased by pressurization of feed gas. An independent claim is also included for a device for performing a method for utilization of lean gas.