Liquefied Gas Tank Joint Thermal Stress Control

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing liquefied gas storage tanks face challenges in determining whether the joint between the tank and the support member is rapidly cooled by the liquefied gas, leading to potential thermal stress issues during loading, especially when the temperature difference between the tank and the support member is small, causing delays in the loading process.

Innovation Solution

A liquefied gas storage tank equipped with a rapid cooling possibility determination device, comprising temperature detection units for the tank partition wall and support member, a temperature difference acquisition unit, and a determination unit, which assesses the temperature difference to determine if rapid cooling is possible, allowing for early initiation of liquefied gas loading while minimizing thermal stress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the tank is precooled to about -100°C before loading, then thermal stress on the joint between tank and support member is reduced, but the loading process takes much more time

Engineering Contradiction:
Improvejoint strengthVSAvoidloading time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent applies preliminary action by performing partial precooling of the tank before loading begins. Temperature detection units monitor the tank and support member temperatures, and when the temperature difference falls within a predetermined range, loading can start immediately without requiring full precooling to -100°C. This preliminary temperature equalization reduces thermal stress while avoiding excessive waiting time.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback through temperature detection units that continuously monitor the temperatures of both the tank and support member. Based on the detected temperature difference, the system provides feedback to determine the optimal loading start timing. When the temperature difference is within the acceptable range, the system signals that loading can proceed, thereby optimizing the balance between joint protection and loading efficiency.

Inventive Principle:
Principle #23Feedback

2Stability of the object's composition

If the tank is precooled to about -100°C before loading, then abrupt temperature lowering is prevented, but excessive precooling time is required

Engineering Contradiction:
Improvetemperature stabilityVSAvoidprecooling duration
Core Design Contradiction:
Stability of the object's compositionVSDuration of action of stationary object

Solution Approach 1:

The patent applies partial action by cooling the tank only to the extent necessary to achieve an acceptable temperature difference with the support member, rather than requiring full precooling to -100°C. The temperature detection units monitor when the temperature difference enters the predetermined safe range, at which point loading can begin. This partial precooling approach maintains temperature stability sufficient to prevent thermal stress while significantly reducing the precooling duration.

Inventive Principle:
Principle #16Partial or excessive action

3Reliability

If loading starts when temperature difference is small, then thermal stress is minimized, but determination of rapid cooling possibility becomes difficult

Engineering Contradiction:
Improvejoint integrityVSAvoidcooling rate detection
Core Design Contradiction:
ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent uses feedback from temperature detection units positioned on both the tank and support member to continuously measure the temperature difference. This real-time feedback enables accurate determination of when the temperature difference falls within the predetermined range, providing clear objective criteria for starting loading without difficulty in detecting the optimal moment.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent replaces subjective judgment about cooling rates with an objective measurement system using temperature detection units. Instead of relying on mechanical or empirical methods to assess cooling possibility, the system uses direct temperature measurements and calculated temperature differences to determine the optimal loading start time, making detection precise and unambiguous.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 solution enables the early start of liquefied gas loading by determining if the joint is rapidly cooled, reducing the precooling time and minimizing thermal stress, thus optimizing the loading process.

Implementation Method 1

a first temperature detection unit that detects a temperature of a partition wall of a tank main body in which the liquefied gas is contained

Methodology Applied
Scientific EffectTemperature detection:

Implementation Method 2

a second temperature detection unit that detects a temperature of a support member that supports the tank main body

Methodology Applied
Scientific EffectTemperature detection:

Implementation Method 3

a temperature difference acquisition unit that acquires a temperature difference between the temperature of the partition wall which is detected by the first temperature detection unit and the temperature of the support member which is detected by the second temperature detection unit

Methodology Applied
Scientific EffectTemperature difference measurement:

Implementation Method 4

the tank and the support member are cooled. In this case, the tank that is in direct contact with the liquefied gas is cooled before the support member

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 5

when a temperature of the tank is abruptly lowered and the tank shrinks, great thermal stress may act on a joint between the tank and the support member

Methodology Applied
Scientific EffectThermal stress: Thermal Shock

Implementation Method 6

when a temperature of the tank is abruptly lowered and the tank shrinks

Methodology Applied
Scientific EffectThermal contraction: Thermal Contraction

Data Source

PatentEP3441664B1Liquefied gas storage tank and liquefied gas loading method
Publication Date: 2021.08.25 MITSUBISHI SHIPBUILDING CO LTD
  • EP3441664B1 patent drawingFigure 1
  • EP3441664B1 patent drawingFigure 2
  • EP3441664B1 patent drawingFigure 3~4

AI summary

In the present invention, a control device (30) includes a first temperature detection unit (31) that detects a partition wall temperature (T1) of a tank body where liquefied gas is housed, and a second temperature detection unit (32) that detects a temperature (T2) of a skirt supporting the tank body. The control device (30) further includes a temperature difference acquisition unit (33) that acquires a temperature difference (ΔT) between the partition wall temperature (T1) detected by the first temperature detection unit (31) and the temperature (T2) of the skirt detected by the second temperature detection unit (32), and a determination unit (34) that determines whether it is possible to rapidly cool a joining part of the tank body and the skirt with liquefied gas on the basis of the partition wall temperature (T1) and the temperature difference (ΔT).