Single-Methane Expander LNG Liquefaction at Intermediate Pressure
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Solution Overview
Problem
Current liquefaction systems for natural gas are costly and operationally complex, particularly due to the need for multiple expanders and refrigerants, which increase capital and operational expenses.
Innovation Solution
A liquefaction system that circulates fluid derived from the incoming natural gas at an intermediate pressure between the high pressure of the feedstock and the low pressure of boil-off gas, using a single methane expander to reduce expansion ratio and provide sufficient refrigeration duty, thereby simplifying the system and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple expanders and refrigerants are used in the liquefaction system, then the refrigeration duty is sufficient, but the capital costs and operational complexity increase
Solution Approach 1:
The patent combines multiple expander functions into a single methane expander by introducing an intermediate pressure stage. The expander operates at an intermediate pressure between the high pressure of incoming feedstock and the low pressure of boil-off gas, merging the functions of multiple expanders into one unified device that achieves sufficient refrigeration duty while reducing system complexity
Solution Approach 2:
The patent changes the pressure parameter by operating the methane expander at an intermediate pressure level. This parameter change allows a single expander to achieve the refrigeration effect that previously required multiple expanders operating at different pressure levels, thereby reducing device complexity while maintaining reliability
2Reliability
If multiple expanders and refrigerants are used in the liquefaction system, then the refrigeration duty is sufficient, but the capital costs increase
Solution Approach 1:
The patent merges multiple expander units into a single methane expander operating at intermediate pressure, reducing the number of capital-intensive components required. This consolidation maintains sufficient refrigeration duty while lowering capital costs by eliminating redundant equipment
Solution Approach 2:
The patent extracts the essential refrigeration function from a multi-expander system and concentrates it into a single methane expander operating at intermediate pressure. This extraction eliminates unnecessary components and reduces capital costs while preserving the core refrigeration capability
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 configuration reduces capital and operational costs by allowing efficient liquefaction with a single methane expander, eliminating the need for multiple expanders and refrigerants, while maintaining the quality of the LNG product.
Implementation Method 1
a methane expander that receives the circulating hydrocarbon stream and expands the stream from the first pressure to a second pressure
Implementation Method 2
a heat exchanger that receives an incoming hydrocarbon feedstock and cools the incoming hydrocarbon feedstock with the circulating hydrocarbon stream to form a liquefied natural gas (LNG) product
Data Source
AI summary
A liquefaction system that is configured to use a single methane expander to provide primary refrigeration duty. The liquefaction system can include a heat exchanger and a fluid circuit coupled with the heat exchanger, the fluid circuit configured to circulate a process stream derived from an incoming feedstock of natural gas. The fluid circuit can comprise a methane expander coupled with the heat exchanger, a sub-cooling unit coupled with the methane expander, the sub-cooling unit configured to form a liquid natural gas (LNG) product from the process stream, and a first throttling device interposed between the heat exchanger and the sub- cooling unit. The methane expander and the first throttling device can be configured to expand the process stream to a process pressure that is between a first pressure of the incoming feedstock and a second pressure of the process that exits the sub-cooling unit.