Method and process plant for liquefaction of gas
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Solution Overview
Problem
Existing small-scale gas liquefaction plants require complex setups with multiple heat exchangers and are costly, making them unsuitable for local distribution and small gas fields, where low investment costs and simplicity are essential.
Innovation Solution
A method and plant using conventional two-flow heat exchangers and oil-lubricated compressors, where the refrigerant is processed in a way that prevents oil contamination, allowing for efficient liquefaction of natural gas in a simplified configuration with fewer heat exchangers and no special refrigerant distribution equipment, enabling cost-effective operation and easy transportation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional small-scale liquefaction plants use multiple heat exchangers in complex setups, then liquefaction efficiency is improved, but investment costs and device complexity increase significantly
Solution Approach 1:
The patent combines multiple heat exchanger functions into a single integrated heat exchanger unit. The condensing fluid channel and vaporizing fluid channel are merged into one device, eliminating the need for separate heat exchangers for different stages of the liquefaction process. This reduces device complexity while maintaining liquefaction efficiency through optimized internal flow paths and heat transfer surfaces.
Solution Approach 2:
The single heat exchanger performs multiple functions simultaneously: it serves as both the primary heat exchanger for condensing the most volatile refrigerant component and as the secondary heat exchanger for vaporizing and cooling the multi-component refrigerant. This multi-functional design eliminates the need for separate dedicated heat exchangers for each function, reducing overall system complexity.
2Reliability
If special refrigerant distribution equipment is added to prevent oil contamination, then refrigerant purity is improved, but device complexity and investment costs increase
Solution Approach 1:
The system uses the natural properties of the refrigerant components and the established flow paths through the heat exchanger to achieve self-cleaning and self-protection against oil contamination. The flow direction and temperature gradients naturally prevent oil from reaching critical areas, eliminating the need for additional active protection equipment while maintaining refrigerant purity.
3Adaptability or versatility
If the plant is designed for small-scale operation to reduce investment costs, then adaptability to local distribution and small gas fields is improved, but liquefaction capacity per unit time is reduced
Solution Approach 1:
The patent optimizes the operating parameters of the single heat exchanger, including flow rates, pressure levels, and temperature differentials, to maximize liquefaction efficiency within the constraints of small-scale operation. By carefully controlling these parameters, the system achieves effective liquefaction at reduced capacity, making it suitable for local distribution and small gas fields while maintaining economic viability.
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 solution provides a cost-effective, simple, and efficient method for small-scale liquefaction of natural gas, preventing oil contamination and reducing energy consumption, making it suitable for various applications including local distribution, remote gas fields, and reducing environmental impact.
Implementation Method 1
The product gas is cooled and condensed to give liquid product gas in a first heat exchanger by heat exchange with a multi-component refrigerant
Implementation Method 2
The product gas is cooled and condensed to give liquid product gas
Implementation Method 3
The refrigerant is evaporated by the product gas to be cooled in a second heat exchanger
Implementation Method 4
The refrigerant is evaporated by the product gas to be cooled in a second heat exchanger
Implementation Method 5
said gaseous refrigerant is compressed in at least one compressor to a pressure and temperature at which said gaseous refrigerant can be condensed
Implementation Method 6
said gaseous refrigerant is condensed in a heat exchanger by the liquid product gas to give a liquid refrigerant
Data Source
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AI summary
The present invention relates to a process plant and method for cooling and optionally liquefaction of a product gas, particularly for liquefaction of natural gas, based on a closed loop of multi-component refrigerant in heat exchange with the gas to be cooled and optionally condensed. The process plant is comprises at least one primary heat exchanger (20) arranged to cool the product gas directed to the heat exchanger (10), at least one compressor (46) arranged to compress the low level refrigerant directed from the first of the at least two secondary heat exchangers (64), at least one pre-cooling heat exchanger (54) to sub-cool and partly liquefy the compressed refrigerant, at least one phase-separator (60) arranged to separate the partly liquefied multi-component refrigerant into a more volatile fraction and a less volatile fraction, at least two secondary heat exchangers (64, 114), the first of the at least two secondary heat exchangers (64) arranged to cool the more volatile fraction from the phase-separator (62), and the second of the at least two secondary heat exchangers (114) arranged to cool further the more volatile fraction, a throttling device (118) arranged to reduce the pressure of a part of the more volatile fraction to become the low level refrigerant to be heat exchanged in the second of at least two secondary heat exchangers, a throttling device (76) arranged to reduce the pressure of a part of the more volatile fraction to become the low level refrigerant to be heat exchanged in the at least one primary heat exchanger (20), a throttling device (102) arranged to reducing the pressure of the less volatile fraction from the at least one phase-separator (60) to become part of the low level refrigerant, for mixing with the low level refrigerant from the at least one primary heat exchanger (20), and the low level refrigerant from the second of at least two secondary heat exchangers (114) this directed to heat exchange through the first of at the least two secondary heat exchangers (64).