Production of helium from a stream of natural gas
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Solution Overview
Problem
Current methods for extracting helium from natural gas streams containing methane and nitrogen face challenges in achieving high helium content and yield while minimizing equipment complexity and energy consumption, often requiring additional separation columns or processes that compromise between purity and efficiency.
Innovation Solution
A double-column nitrogen rejection unit process involving high and low-pressure distillation columns, condensation, expansion, and phase separation stages, where the liquid phase is used as reflux and expanded to vaporize helium in a first separator pot, followed by partial condensation in a second separator pot to achieve a helium-enriched gas stream with over 50% volume helium content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a dual-column NRU unit with successive partial condensations and flash vaporizations is used, then the equipment complexity is reduced, but the helium purity and yield cannot both be high
Solution Approach 1:
The invention changes the pressure parameter during the separation process. By operating the first separator at high pressure and the second separator at low pressure, the process achieves both high helium purity (>50%) and high yield (>85%) without requiring a dedicated helium separation column, thus resolving the contradiction between equipment complexity and helium purity
Solution Approach 2:
The invention utilizes phase transitions (condensation and vaporization) at different pressure levels to separate helium from the natural gas stream. The high-pressure separator performs initial separation, followed by low-pressure separator that achieves final high-purity helium recovery through controlled phase changes, eliminating the need for additional distillation columns
2Manufacturing precision
If a dedicated helium separation column is added to distill nitrogen and helium, then the helium purity is improved, but the device complexity and energy consumption increase
Solution Approach 1:
The invention merges the nitrogen rejection function and helium separation function into a single integrated NRU unit. The double-column NRU with two separators performs both nitrogen removal and helium enrichment simultaneously, eliminating the need for a dedicated helium separation column while achieving >50% helium purity and >85% yield
Solution Approach 2:
The NRU unit is designed to perform multiple functions: nitrogen rejection, helium enrichment, and partial condensation. The same equipment (double-column NRU with two separators) handles both nitrogen removal and helium separation, making the system universal and avoiding additional dedicated equipment
3Manufacturing precision
If a dedicated helium separation column is added to distill nitrogen and helium, then the helium purity is improved, but the energy consumption increases
Solution Approach 1:
The invention combines nitrogen rejection and helium separation into one integrated process using a double-column NRU with two separators. This eliminates the need for a separate dedicated helium separation column and its associated refrigeration cycling, reducing overall energy consumption while maintaining high helium purity through pressure-based separation
4Device complexity
If successive partial condensations and flash vaporizations are used, then the equipment complexity is reduced, but both high helium content and high yield cannot be achieved simultaneously
Solution Approach 1:
The invention changes the pressure parameter between separators to optimize helium recovery. The first separator operates at high pressure for initial separation, and the second separator operates at low pressure to maximize helium yield. This pressure-based two-stage separation achieves both high helium content (>50%) and high yield (>85%) with simple equipment
Solution Approach 2:
The invention uses controlled phase transitions at different pressure levels to sequentially separate helium. The high-pressure separator performs initial phase separation, and the low-pressure separator completes the helium enrichment through further phase changes, achieving high yield without complex equipment
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 process achieves high helium yield (>85%) and content (>50%) without dedicated helium separation columns, reducing equipment and energy costs while maintaining high purity, thereby optimizing helium extraction from natural gas streams.
Implementation Method 1
introduction of said source gas stream into a double-column nitrogen rejection unit, said double column comprising a high-pressure distillation column, a low-pressure distillation column
Implementation Method 2
a condenser connecting the high-pressure column with the low-pressure column; extraction from said condenser of at least a portion of a mixture produced at the top of the high-pressure column
Implementation Method 3
expansion of said mixture from step b) to an intermediate pressure between 8 bar and 20 bar absolute
Implementation Method 4
separation of the mixture from step c) in a first phase separator into a liquid phase and a helium-enriched gas phase
Implementation Method 5
at least partial condensation of said helium-enriched gas phase in a heat exchanger
Implementation Method 6
Separation of the stream from step e) in a second phase separator pot into a liquid phase and a gaseous phase containing more than 50% by volume of helium
Implementation Method 7
use, as a refrigerant, of the liquid phase after expansion from step (f) in said heat exchanger implemented in step (e)
Data Source
Figure 1
AI summary
The invention relates to a method for producing a helium gas stream (27) from a source gas stream (1) comprising at least helium, methane and nitrogen, comprising at least the following steps: step a): introducing said source gas stream (1) into a double column nitrogen rejection unit (6), said double column comprising a high-pressure distillation column (5), a low-pressure distillation column (7) and a condenser (8) linking the high-pressure column (5) with the low-pressure column (7); step b): extracting at the outlet of said condenser (8) at least a part (12) of a mixture (11) produced at the head of the high-pressure column (5); step c): reducing the pressure of said mixture from step b) to an intermediate pressure of between 8 and 20 bar absolute; step d): separating the mixture (14) from step c) in a first phase separation chamber (15) into a liquid phase (16) and a helium-enriched gas phase (17); step e): at least partially condensing said helium-enriched gaseous phase (17) in a heat exchanger (24); and step f): separating the stream (25) coming from step e) in a second phase separation chamber (26) into a liquid phase (28) and a gas phase (27) containing more than 50% by volume of helium.