Concentric LNG Rotary Joint for Vapor Return and Thermal Insulation
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Solution Overview
Problem
The challenge of efficiently transferring natural gas between different states (gaseous and liquid) due to significant volume changes and maintaining thermal insulation during transfer, particularly in offshore installations, is not adequately addressed by existing technologies.
Innovation Solution
A fluid transfer system with concentric liquid and gas transfer ducts, incorporating a buffer element to separate and manage vaporized portions of liquefied gas, ensuring thermal insulation and pressure equilibrium, using dynamic sealing elements and pressurization to prevent leaks and maintain liquid state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If natural gas is stored in liquid state (LNG) to reduce volume, then storage efficiency improves, but thermal insulation requirements increase significantly
Solution Approach 1:
The patent implements a concentric duct configuration where the liquid transfer duct is nested within the gas transfer duct. The liquid duct carries LNG at cryogenic temperatures while the surrounding gas duct carries vaporized natural gas. This nested arrangement provides thermal insulation by creating a thermal barrier between the cold liquid and the warmer external environment, while also utilizing the warmer gas flow to reduce heat ingress to the liquid LNG.
Solution Approach 2:
The buffer element positioned between the liquid and gas ducts acts as an intermediary thermal barrier. This element, which may be insulating material or a thermal management component, mediates heat transfer between the cold liquid phase and the warmer gas phase, reducing thermal ingress to the LNG while allowing efficient heat extraction for vaporization control.
2Loss of substance
If vaporized portion of LNG is returned to liquefaction unit, then production losses are minimized, but system complexity increases
Solution Approach 1:
The patent combines the liquid transfer function and gas return function into a single integrated concentric duct system. The liquid transfer duct and gas transfer duct share the same physical pathway, with the liquid duct inside and gas duct outside. This merging eliminates the need for separate parallel pipelines, reducing system complexity while ensuring that vaporized portions are efficiently returned to the liquefaction unit for re-liquefaction.
Solution Approach 2:
The system utilizes the natural buoyancy and temperature differential to drive the return of vaporized gas. The warmer vaporized natural gas naturally rises and flows back through the outer gas duct to the liquefaction unit without requiring additional pumping energy, making the system self-service for the gas return function.
3Temperature
If concentric duct configuration is used for liquid and gas transfer, then thermal insulation improves, but device complexity increases
Solution Approach 1:
The concentric duct configuration with liquid duct nested within gas duct provides inherent thermal insulation. The outer gas duct acts as a thermal shield, and the buffer element between them enhances insulation. This nested structure is more efficient than separate parallel ducts because it creates a controlled thermal gradient and reduces heat ingress to the liquid LNG.
Solution Approach 2:
The concentric duct configuration serves multiple functions simultaneously: it provides thermal insulation for the liquid LNG, creates a pathway for vaporized gas return, enables pressure equilibrium between phases, and reduces overall space requirements compared to separate duct arrangements. This multi-functionality justifies the increased structural complexity.
4Reliability
If buffer element is added between liquid and gas ducts, then pressure equilibrium and leak prevention improve, but device complexity increases
Solution Approach 1:
The buffer element positioned between the liquid and gas ducts acts as an intermediary pressure management zone. It allows pressure equilibrium between the cold liquid phase and warmer gas phase, preventing pressure differentials that could cause leaks. The buffer element may also serve as an additional thermal barrier and leak detection zone, enhancing system reliability.
Solution Approach 2:
The buffer element provides beforehand cushioning by creating a pressure buffer zone that prevents sudden pressure changes from propagating between the liquid and gas ducts. This cushioning effect protects the system from pressure-induced leaks and maintains stable operating conditions.
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 system effectively transfers liquefied gas while managing vaporized fractions, maintaining thermal insulation and pressure balance, reducing leaks, and enhancing operational safety and reliability.
Implementation Method 1
a buffer element, disposed between the liquid transfer duct and the gas transfer duct and at least partially surrounding the liquid transfer duct, the buffer element being configured to transfer a vaporized portion of the liquefied gas flowing in the liquid transfer duct from the liquid transfer duct to the gas transfer duct
Implementation Method 2
maintaining thermal insulation and pressure balance
Implementation Method 3
using dynamic sealing elements and pressurization to prevent leaks and maintain liquid state
Data Source
Figure 1~2
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AI summary
Fluid transfer system (100) comprising a concentric liquid transfer conduit (110) and gas transfer conduit (120), the gas transfer conduit (120) surrounding the liquid transfer conduit (110), and a buffer element (130) disposed between the liquid transfer conduit (110) and the gas transfer conduit (120) and at least partially surrounding the liquid transfer conduit (110), the buffer element (130) being configured to transfer an evaporated portion of the liquefied gas flowing in the liquid transfer conduit (110) from the liquid transfer conduit (110) to the gas transfer conduit (120). Rotary joint device (1000) comprising such a system (100), stack (1010) of rotary joint devices, and fluid handling installation (1).