Helium extraction from natural gas
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Solution Overview
Problem
Current helium extraction processes from natural gas streams with low helium concentrations are economically unfeasible due to high power consumption and the need for multiple distillation trains, especially when integrating membranes with cryogenic distillation, and face challenges in separating helium at low feed flow rates and high methane content.
Innovation Solution
A process that uses a membrane system to concentrate helium by an order of magnitude, followed by partial condensation and cryogenic distillation at reduced pressure to enhance helium separation efficiency, combined with pressure swing adsorption for purification, reducing the size of the distillation section and overall power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If cryogenic distillation is used to extract helium from natural gas with low helium concentrations, then helium can be separated, but multiple parallel distillation trains are required which increases capital cost and complexity
Solution Approach 1:
The patent applies preliminary action by using a membrane separation system before the distillation column to pre-concentrate helium from the natural gas feed. This preliminary concentration step increases the helium content in the feed to the distillation column, allowing a single distillation train to handle the feed effectively rather than requiring multiple parallel trains.
2Quantity of substance
If cryogenic distillation is used on low concentration helium feeds, then helium separation is attempted, but the ratio of liquid to vapor flow rates becomes very high making separation challenging
Solution Approach 1:
The membrane system performs preliminary concentration of helium, transforming the low-concentration feed into a higher-concentration stream before distillation. This preliminary action adjusts the feed composition to achieve a more favorable liquid-to-vapor flow rate ratio in the distillation column, enabling effective helium separation.
3Quantity of substance
If membrane extraction is integrated with distillation, then helium concentration is improved, but the distillation section size must be reduced to be economical
Solution Approach 1:
The patent applies parameter changes by operating the distillation column at reduced pressure (e.g., 1-10 psia) compared to conventional atmospheric pressure operations. This pressure reduction, combined with the membrane-preconcentrated feed, allows the distillation column to achieve the required separation with a smaller diameter and reduced volume, making the integrated process economical.
4Adaptability or versatility
If helium is extracted from natural gas without liquefaction or nitrogen rejection, then the natural gas can be used in pipeline or gas turbine, but helium recovery becomes more difficult
Solution Approach 1:
The patent applies segmentation by dividing the helium recovery process into two independent modules: (1) a membrane separation system that concentrates helium from the natural gas feed, and (2) a distillation system that purifies the concentrated helium. This segmented approach allows helium recovery to be implemented as a standalone process without requiring full liquefaction or nitrogen rejection, maintaining the versatility of natural gas usage while achieving effective helium recovery.
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 approach significantly reduces capital costs by minimizing the size of the cryogenic distillation section, lowers power consumption, and achieves high helium recovery and purity, making helium extraction more economical from natural gas streams with low helium concentrations.
Implementation Method 1
introducing said natural gas feed to a membrane separation system to produce a helium-enriched permeate stream
Implementation Method 2
separating said cooled permeate stream in a first distillation column system to produce a helium-enriched overhead vapor and a first helium-depleted bottoms liquid
Implementation Method 3
The crude helium vapor is purified by pressure swing adsorption
Data Source
AI summary
A helium-containing stream is recovered from a natural gas feed using a membrane followed by multiple distillation steps. Refrigeration is provided by expanding a bottoms liquid with a higher nitrogen content than the feed, achieving a lower temperature in the process. The helium-enriched vapor is then purified and the helium-containing waste stream is recycled to maximize recovery and reduce the number of compressors needed. The helium-depleted natural gas stream can be returned at pressure for utilization or transportation.