Integrated Flash Gas Heat Exchanger for Compact LNG Separation
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Solution Overview
Problem
Conventional LNG liquefaction systems require significant plot space due to separate vapor-liquid separators and flash gas heat exchangers, which is a challenge for remote offshore and small-scale liquefaction facilities where space is limited.
Innovation Solution
A compact system integrating a shell casing with a heat exchange zone and a separation zone, where flash gas is separated from the LNG stream and refrigeration is recovered, eliminating the need for separate vessels and reducing the overall footprint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate vapor-liquid separator and flash gas heat exchanger are used, then reliable flash gas separation and refrigeration recovery are achieved, but large plot space is required
Solution Approach 1:
The patent combines the vapor-liquid separator and flash gas heat exchanger into a single integrated unit. The separator vessel includes an internal heat exchanger assembly that allows flash gas to be separated and simultaneously cooled/refrigeration recovered within the same equipment, eliminating the need for separate external heat exchanger and reducing plot space requirement
Solution Approach 2:
The heat exchanger coils are nested inside the separator vessel. The heat exchange tubes are positioned within the separator chamber, allowing the flash gas to flow through the coils while being cooled by the refrigeration system, effectively nesting one functional component within another to reduce overall footprint
2Adaptability or versatility
If separate vessels with piping are used, then functional requirements are met, but equipment complexity and footprint increase
Solution Approach 1:
The patent integrates multiple functions into a single separator vessel: vapor-liquid separation, flash gas cooling, and refrigeration recovery all occur within one piece of equipment. The internal heat exchanger assembly eliminates the need for external piping connections between separate vessels, reducing equipment complexity and potential leak points
3Ease of operation
If conventional land-based system layout is used, then adequate space for maintenance is provided, but the system is not suitable for floating platforms with limited space
Solution Approach 1:
The integrated separator design consolidates multiple functions into one compact unit that occupies significantly less plot space, making it suitable for floating platforms. The design maintains operational accessibility while reducing the overall footprint to fit constrained marine environments
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 integrated approach allows for more efficient use of space, reduces equipment count, and lowers the power required for recompression, making it suitable for Floating LNG and small-scale facilities.
Implementation Method 1
the heat exchange zone, configured to recover refrigeration from the separated flash gas
Implementation Method 2
the separation zone, configured to separate a flash gas from the LNG product
Data Source
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AI summary
Described herein are methods and systems for the liquefaction of natural gas to produce a LNG product. The methods and systems use an apparatus for separating a flash gas from a liquefied natural gas (LNG) stream to produce a LNG product and recovering refrigeration from the flash gas. The apparatus includes a shell casing enclosing a heat exchange zone comprising a coil wound heat exchanger, and a separation zone. The heat exchange zone is located above and in fluid communication with the separation zone. Flash gas is separated from the LNG product in the separation zone and flows upwards from the separation zone into the heat exchange zone where refrigeration is recovered from the separated flash gas.