Multi-Stage Membrane Gas Separation with Recycle Loop
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing gas permeation devices for separating gas mixtures into product gas and off-gas suffer from low product gas concentration and yield, high energy requirements, and economic limitations, particularly in biogas plants where the off-gas requires enrichment for burning.
Innovation Solution
A device with at least two membrane units and a compressor connected upstream of the first membrane unit, where the retentate of the first membrane unit is used as feed for the second, and the permeate is recycled and mixed with additional permeate to control the concentration of product gas in the off-gas, using control valves and compressors to regulate system pressure and permeate flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a one-stage membrane unit is used for gas separation, then the device structure is simple, but the product gas concentration and yield are low with increased energy requirement
Solution Approach 1:
The gas separation process is divided into multiple stages using at least two membrane units arranged in series. The retentate from the first membrane unit becomes the feed gas for the second membrane unit, allowing progressive separation and achieving higher product gas concentration and yield while maintaining manageable system complexity through modular segmentation.
2Productivity
If a two-stage membrane unit with compression is used, then the product gas yield is improved, but the product gas quality remains low and energy requirement increases
Solution Approach 1:
The system incorporates a compressor with variable speed control to dynamically adjust the pressure differential across membrane units based on operating conditions. This allows optimization of both product gas yield and quality by adapting compression levels to match the specific separation requirements at each stage, preventing excessive compression that would degrade gas quality while maintaining sufficient compression for high yield.
3Quantity of substance
If the compressor speed is increased to improve product gas concentration in off-gas, then the concentration is improved, but the energy consumption increases
Solution Approach 1:
The system employs control valves and speed control mechanisms that respond to real-time conditions in the off-gas stream. By monitoring product gas concentration and adjusting compressor speed or valve positions accordingly, the system maintains optimal concentration levels in the off-gas while minimizing energy consumption through feedback-based optimization rather than continuous high-speed compression.
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 configuration allows for improved regulation of product gas concentration in the off-gas, enhancing energy efficiency and economic viability by optimizing permeate flow and pressure management, specifically increasing product gas concentration for effective use in biogas combustion.
Implementation Method 1
separating a gas mixture into product gas and off-gas by means of gas permeation
Implementation Method 2
a compressor (3) connected upstream of the first membrane unit (1)
Data Source
Figure 1
AI summary
The invention relates to a device for regulating the concentration of product gas in an offgas when separating a gas mixture into product gas and offgas by means of gas permeation, with at least two membrane units (1) and (2) and a compressor (3) upstream of the first membrane unit (1), which membrane units (1) and (2) have a gas inlet (1a, 2a), a retentate outlet (1b, 2b) and permeate outlets (1c, 1d and 2c), wherein the retentate outlet (1b) of the first membrane unit (1) is connected to the gas inlet (2a) of the second membrane unit (2), and the permeate outlet (2c) of the second membrane unit (2) is connected on the intake side to the compressor (3) respectively.The gas supply leading to the compressor and the compressor (3) are connected by a line to the gas inlet (1a) of the first membrane unit (1), product gas is obtained via the retentate outlet (2b) and off-gas via the permeate outlet (1c), wherein, according to the invention, the permeate outlet (1d) of the first membrane unit (1) is connected by a line to the line between the permeate outlet (2c) of the second membrane unit (2) and the compressor (3) or the gas supply leading to the compressor. The present invention further relates to such a method.