Membrane System for High Methane Recovery
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Solution Overview
Problem
Existing multi-stage membrane systems for methane recovery from biogas require excessive compressor power and membrane area due to the need for continuous recompression and sweep gas usage, which increases operational costs and reduces efficiency.
Innovation Solution
A method and system where only the raw feed gas and low-pressure recycle streams are compressed, with permeate streams not being recompressed or used as sweep gases, optimizing the membrane stages and compressor usage to achieve high methane recovery with reduced energy consumption and membrane area requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If permeate streams are continuously recompressed in multi-stage membrane systems, then methane recovery is improved, but compressor power consumption increases excessively
Solution Approach 1:
The invention extracts the recompression step for permeate streams between stages, eliminating the need to compress these streams. Only the raw feed gas and low-pressure recycle streams are compressed, while permeate streams are fed directly to subsequent stages, thereby reducing compressor power consumption while maintaining methane recovery
Solution Approach 2:
Instead of the conventional approach where permeate streams are recompressed before feeding to the next stage, the invention inverts this by feeding permeate streams directly without compression. The system is designed to accept low-pressure feed gas at the next stage, reversing the traditional pressure management strategy
2Manufacturing precision
If permeate streams are used as sweep gas in subsequent stages, then separation efficiency is improved, but operational complexity and energy consumption increase
Solution Approach 1:
The invention removes the sweep gas function from the system by not using permeate streams as sweep gas. Each stage operates independently with its own feed stream, eliminating the complexity of managing sweep gas flows and the associated energy consumption while maintaining effective separation
3Reliability
If more membrane stages are added to increase methane recovery, then separation performance is improved, but membrane area requirements and system complexity increase
Solution Approach 1:
The invention segments the membrane system into multiple stages that can process different pressure levels independently. Each stage is optimized for its specific function, allowing the system to achieve high methane recovery through coordinated operation of simplified individual stages rather than requiring a single complex large-scale membrane system
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 approach achieves at least 99.5% methane recovery with significantly lower compressor power costs and reduced membrane area needs, enhancing the efficiency and cost-effectiveness of biogas upgrading processes.
Implementation Method 1
separating a pressurized feed gas stream into a first nonpermeate stream and a first permeate stream
Data Source
AI summary
A method for separating a raw feed gas stream using a plurality of membrane separation stages includes separating a pressurized feed gas stream into a first nonpermeate stream and a first permeate stream, compressing the first permeate stream to form a compressed first permeate stream, separating the compressed first permeate stream into a second nonpermeate stream and a second permeate stream, separating the second permeate stream into a third nonpermeate stream and a third permeate stream, combining the third nonpermeate stream with a raw feed gas stream to form a combined feed stream, compressing the combined feed stream to form a compressed combined feed stream, and combining the second nonpermeate stream with the compressed combined feed stream to form the pressurized feed gas stream.