Cryogenic Helium Recovery Process for Natural Gas
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Solution Overview
Problem
Existing cryogenic processes for helium recovery from natural gas suffer from helium loss due to high pressure and low-temperature conditions, leading to increased costs and inefficiencies, especially when processing low-pressure natural gas with low helium concentration.
Innovation Solution
A cryogenic process that involves pretreating natural gas, cooling it, and subjecting it to multiple flash stages and heat exchangers to minimize helium loss, with a hybrid system that recycles purge streams and uses reduced operating pressures to enhance helium recovery and reduce capital and operating costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high pressure and low-temperature conditions are used in cryogenic processes for helium recovery, then helium separation efficiency is improved, but helium loss increases
Solution Approach 1:
The patent applies parameter changes by operating the cryogenic process at reduced pressures (0.5-2.0 bar gauge pressure) compared to conventional high-pressure operations. This pressure parameter change allows the process to achieve effective helium separation while minimizing helium loss to condensation, directly resolving the technical contradiction between separation efficiency and helium loss.
Solution Approach 2:
The patent implements preliminary action through a pretreatment step that removes impurities (water vapor, CO2, H2S, higher hydrocarbons) from natural gas before the cryogenic separation process. This preliminary purification prevents impurity-related complications during cryogenic operation, enabling the process to maintain low temperatures and reduced pressures without compromising separation efficiency or increasing helium loss.
2Productivity
If compression is applied to low-pressure natural gas for helium recovery, then processing capability is improved, but compression energy consumption increases
Solution Approach 1:
The patent fundamentally changes the pressure parameter by designing the cryogenic process to operate at reduced pressures (0.5-2.0 bar gauge) rather than requiring high-pressure compression of feed gas. This parameter change enables the process to handle low-pressure natural gas directly, dramatically reducing compression energy consumption while maintaining processing capability through optimized cryogenic separation at these lower pressures.
3Productivity
If conventional cryogenic processes are used for helium recovery from low-concentration natural gas, then helium production is achieved, but capital and operating costs increase
Solution Approach 1:
The patent applies parameter changes by operating at reduced pressures (0.5-2.0 bar gauge) and optimized temperatures, which reduces the scale and complexity of compression equipment, heat exchangers, and separation units required. This directly lowers capital costs. Operating at these milder conditions also reduces energy consumption for compression and cooling, thereby reducing operating costs while maintaining helium production capability from low-concentration natural gas.
Solution Approach 2:
The patent implements preliminary removal of impurities (water vapor, CO2, H2S, higher hydrocarbons) before the cryogenic process. This pretreatment prevents impurity-related operational problems that would increase maintenance and operating costs, while also improving the efficiency of the subsequent cryogenic separation, thereby reducing both capital and operating costs for helium production from low-concentration natural gas.
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 process achieves 100% helium recovery with reduced capital and operating costs, minimizing helium loss and compression energy, and allows for the production of pure helium from low-pressure natural gas with low helium concentration, making helium production more economically feasible.
Implementation Method 1
subjecting the pretreated natural gas to heat exchanger for its cooling
Implementation Method 2
cooling it, and subjecting it to multiple flash stages and heat exchangers
Implementation Method 3
subjecting a partially condensed gas to throttling device to reduce its pressure
Implementation Method 4
generating an uncondensed gas stream and liquid stream
Implementation Method 5
subjecting a cooled gas stream to a separating vessel for generating the crude helium and liquid stream
Data Source
AI summary
The present invention relates to a cryogenic process to produce crude helium from pretreated natural gas. The pretreated natural gas is processed in two flash stages using the helium free process stream as a stripping agent, and a distillation column with the identified operating conditions and process scheme to ensure 100% helium recovery with reduced capital and operating cost for producing the crude helium. The integration of the cryogenic process with the already known purification system to produce pure helium is demonstrated to ensure high helium recovery in a hybrid process.