Three-Stage Helium Recovery Membrane Process
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Solution Overview
Problem
Current membrane separation methods for helium from natural gas face challenges in achieving high recovery and selectivity due to low helium concentrations, requiring multiple stages and high compressor costs, which are inefficient and costly.
Innovation Solution
A three-stage membrane separation process where the first and third non-permeates are combined to produce a high-purity natural gas stream, with the second permeate being injected back into the reservoir to enhance helium recovery and minimize heating value loss, using polymeric membranes that preferentially permeate helium over other gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple membrane stages are used to achieve high helium recovery and purity, then helium recovery and selectivity are improved, but device complexity and capital costs increase due to multiple compressors
Solution Approach 1:
The membrane separation process is divided into three distinct stages, each with a specific function: the first stage performs initial separation, the second stage provides intermediate purification, and the third stage achieves final high-purity separation. This segmentation allows each stage to be optimized for its specific separation task, achieving high overall helium recovery without requiring excessive compression capacity in a single stage.
Solution Approach 2:
The invention merges the permeate streams from the first and third membrane stages and combines them with the retentate from the second stage to form the final product stream. This merging strategy allows the system to achieve high helium purity by combining multiple partial separation results, reducing the need for additional compression stages while maintaining high recovery efficiency.
2Manufacturing precision
If multiple membrane stages with permeate recompression are used, then helium selectivity is improved, but operating costs increase due to compressor energy consumption
Solution Approach 1:
The system dynamically adjusts the operating pressures and flow distributions across the three membrane stages to optimize the balance between separation efficiency and compression energy requirements. By controlling the pressure differentials across each membrane stage, the system achieves high helium selectivity while minimizing the total work required by compressors.
Solution Approach 2:
The invention changes the operating parameters (pressure, temperature, flow rates) across different membrane stages to maximize helium separation efficiency. By optimizing these parameters, the system achieves high helium selectivity with reduced compression requirements compared to conventional single-stage or two-stage systems.
3Device complexity
If a single membrane stage is used, then device complexity is reduced, but helium recovery and purity are insufficient for commercial viability
Solution Approach 1:
The separation process is segmented into three functional stages: initial separation (first membrane stage), intermediate purification (second membrane stage), and final high-purity separation (third membrane stage). This segmentation enables the system to achieve commercially viable helium recovery and purity levels that cannot be attained in a single stage, while keeping each individual stage relatively simple.
Solution Approach 2:
The system adds a temporal and functional dimension to the separation process by implementing three sequential membrane stages with different operating conditions. This multi-dimensional approach allows the system to achieve high helium purity by combining multiple partial separations, effectively solving the limitation of single-stage systems without requiring excessive complexity in any single component.
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 achieves high helium recovery and purity with reduced compressor requirements, minimizing operational and capital costs while maintaining a high heating value in the purified natural gas stream.
Implementation Method 1
Helium is typically present in natural gas at below 0.5 mol % levels and is mostly extracted as crude Helium across liquid natural gas (LNG) trains... Small gas molecules such as Helium are well known to be more permeable through glassy polymer membranes than methane or N2... Helium preferentially permeating over the natural gas at the first, second and third gas separation membranes
Data Source
AI summary
Helium-containing natural gas is processed with three gas separation stages to produce a natural gas product and a Helium-containing gas that may be injected into the reservoir from which the Helium-containing natural gas is obtained. A permeate from the first gas separation membrane stage is compressed and fed to the second gas membrane stage. The permeate from the second gas separation membrane stage is recovered as the Helium-containing gas that may be injected into the reservoir. The non-permeate from the second gas separation membrane stage is fed to the third gas separation membrane stage. Non-permeates from the first and third gas separation stages are combined to produce a natural gas product. A permeate from the third gas separation membrane stage is combined with a non-permeate from the first gas separation membrane stage before it is compressed and fed to the second gas separation membrane stage.