LNG Container Segmentation and Vacuum Insulation
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Solution Overview
Problem
Current cryogenic containers for liquefied natural gas (LNG) have limitations in storage capacity and efficiency due to high boil-off rates, leading to increased costs and thicker, heavier construction to manage pressure, which restricts the amount of LNG that can be transported or stored over a given shelf-life.
Innovation Solution
A container system with an outer shell, an inner pressurized container having separate chambers and a heat exchange zone, and an interstitial space with a partial vacuum, utilizing a sacrificial cryogenic fluid to maintain low pressure and reduce boil-off rates, allowing for extended storage and transportation of LNG without refilling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional vacuum insulated ISO containers are used for LNG transport, then the container provides basic thermal insulation, but the boil-off rate remains high at approximately 0.17% per day, limiting storage duration and requiring thicker, heavier construction to manage pressure
Solution Approach 1:
The container is divided into multiple separate chambers instead of a single storage space. Each chamber can be independently pressurized and insulated, allowing for better control of boil-off rates. The segmentation enables the system to maintain lower temperatures and pressures in each compartment, reducing overall energy loss while extending storage duration.
Solution Approach 2:
The patent employs a nested chamber configuration where multiple chambers are arranged within the container volume. This nesting approach maximizes the use of available space while creating multiple thermal zones. The nested structure allows for efficient heat distribution and reduces the surface area exposed to external heat, thereby lowering the boil-off rate and extending storage capability.
2Quantity of substance
If higher pressure ratings are used to increase LNG storage capacity, then more LNG can be stored, but the container requires thicker metal construction which increases weight and cost
Solution Approach 1:
By segmenting the storage into multiple chambers, each chamber can be optimized for specific pressure and temperature conditions. This allows the system to store equivalent or greater quantities of LNG without requiring each individual chamber to withstand maximum pressure, thereby reducing the thickness and weight of metal construction while maintaining total storage capacity.
Solution Approach 2:
The patent changes the operational parameters by using multiple chambers at different pressure levels rather than a single high-pressure chamber. This parameter change allows the system to achieve the same or higher LNG storage capacity with lower individual chamber pressures, resulting in thinner walls and reduced container weight.
3Strength
If thicker metal construction is used to manage pressure in conventional containers, then pressure containment is improved, but the container weight increases and cost increases
Solution Approach 1:
The segmentation of the container into multiple chambers distributes the pressure containment requirements across several smaller structures rather than one large thick-walled chamber. Each chamber can be designed with optimized wall thickness for its specific pressure load, reducing overall material usage and construction complexity while maintaining adequate strength for pressure containment.
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 achieves a boil-off rate of less than 0.20% per day, enabling longer storage and transportation of LNG without refilling, with the potential for thinner, lighter container designs and reduced costs.
Implementation Method 1
The gap between the two vessels is at least partially evacuated to form a vacuum, which provides an insulating barrier and reduces the heat leakage into the cryogenic container from the ambient environment.
Implementation Method 2
at least one heat exchange zone in thermal communication between the first chamber and the at least one other chamber
Data Source
AI summary
Container systems for the transportation and/or storage of Liquefied Natural Gas (LNG) are provided. The container systems include: a) an outer shell; b) an inner pressurized container, wherein the inner pressurized container comprises a first chamber having a first vent and at least one other chamber having a second vent; c) at least one heat exchange zone in thermal communication between the first chamber and the at least one other chamber; and d) an interstitial space between the outer shell and the inner pressurized container including at least a partial vacuum. Methods for transporting and/or storing LNG using the aforementioned container systems are also provided.