Modular LNG Liquefaction With Joule-Thomson Cooling for Small-Scale Supply
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Solution Overview
Problem
Conventional large-scale natural gas liquefaction plants are costly, inefficient, and impractical for small-scale production due to high investment and operating expenses, limited adaptability, and safety concerns associated with storing large volumes of LNG, while existing small-scale solutions are either expensive or inflexible.
Innovation Solution
A compact, modular, and transportable liquefaction method involving a high-pressure cycle with pre-treatment of natural gas to remove impurities, followed by a multi-stage compression and refrigeration process using a propane refrigeration cycle, including a Joule-Thomson expansion valve for efficient liquefaction at low costs and minimal environmental impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional large-scale liquefaction plants are used, then production capacity is high, but investment cost and operating expense are very high
Solution Approach 1:
The patent divides the large-scale liquefaction plant into multiple modular units that can be independently configured. Each module contains complete liquefaction equipment including compressors, heat exchangers, and expansion devices. This segmentation allows the system to be scaled according to actual demand, avoiding the high capital expenditure of oversized conventional plants while maintaining efficient operation at smaller scales.
2Productivity
If conventional large-scale liquefaction plants are used, then production capacity is high, but adaptability to different locations is poor
Solution Approach 1:
The patent employs dynamic modular configuration where the number and arrangement of liquefaction modules can be adjusted based on local gas availability, market demand, and site constraints. This dynamic adaptability allows the same base design to be deployed effectively from small community projects to larger regional facilities, unlike fixed conventional plant designs.
3Reliability
If large volumes of LNG are stored, then future use is secured, but safety risks and storage costs increase
Solution Approach 1:
The patent implements periodic production cycles where LNG is manufactured in smaller batches closer to the time of consumption rather than producing and storing large volumes in advance. This periodic operation pattern reduces the inventory of stored LNG, thereby minimizing safety hazards associated with large storage facilities while still meeting supply requirements through repeated production cycles.
4Quantity of substance
If small-scale liquefaction is implemented, then storage requirements are reduced, but production cost per unit increases
Solution Approach 1:
The patent optimizes operating parameters such as compression pressure, refrigerant flow rates, and heat exchanger temperature differentials to maximize the efficiency of small-scale modules. By carefully tuning these parameters, the system achieves competitive per-unit production costs despite the smaller scale, overcoming the traditional disadvantage of small facilities having higher specific costs.
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
Enables low-cost, flexible, and safe production of LNG on a small scale with minimal environmental impact, low power consumption, and easy installation, suitable for local markets and distributed production near populated areas.
Implementation Method 1
partly liquefying the compressed natural gas in a Joule-Thomson expansion valve
Implementation Method 2
cooling the compressed natural gas to a temperature between -100°C and -160°C
Data Source
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AI summary
A method for the liquefaction of natural gas, comprising: - taking unpurified natural gas from a gas well (101); - pre-treating the gas for removing impurities; - performing a first compression stage (201); - performing a first heat exchange stage (202); - performing a second compression stage (203); - performing a second heat exchange stage (204); - performing a third compression stage (205); - performing a third heat exchange stage (206); - performing an additional regeneration heat exchange stage (207); - performing a first main independent heat exchange cycle (208); - performing a second main heat exchange cycle (209); - passing the gas through a Joule-Thomson valve; - sending the liquefied gas (215) to storage; - injecting the portion of the gas remaining in the gaseous state (210) into the second main heat exchange stage (209) and subsequently re-injecting the remaining gas in the gaseous state into the inlet pipe (122) being mixed with the gas incoming from the treatment plant.