Monitoring Sealed Insulated Vat Combustible Gas

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Solution Overview

Problem

Monitoring leaktight and thermally insulating tanks containing liquefied combustible gases at low temperatures pose challenges in detecting combustible gas presence within the thermally insulating barrier, especially when the gas phase is maintained under negative relative pressure, as existing methods are inefficient and costly.

Innovation Solution

A method and device for monitoring the tank involve sampling the gas phase under negative pressure, adding a measured quantity of inert gas to raise the pressure, and using a gas analyzer to measure combustible gas concentration, with the option to dilute the gas phase using inert gas either upstream or downstream of the sampling process, allowing for efficient detection without risking explosive mixtures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the gas phase in the thermally insulating barrier is maintained under negative relative pressure to improve thermal insulation, then thermal insulation performance is improved, but the difficulty of detecting and measuring combustible gas concentration increases

Engineering Contradiction:
Improvethermal insulation performanceVSAvoidcombustible gas concentration measurement
Core Design Contradiction:
Loss of energyVSDifficulty of detecting and measuring

Solution Approach 1:

The patent changes the pressure parameter of the gas sample from negative relative pressure to positive operating pressure by introducing inert gas, making the sample suitable for analysis by conventional gas analyzers while preserving the original combustible gas concentration information for detection

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

Inert gas acts as an intermediary substance that transfers the combustible gas from the negative pressure environment to the positive pressure analysis system, enabling measurement without direct exposure to the hazardous low-pressure environment

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If conventional monitoring methods are used to detect combustible gas in the thermally insulating barrier, then detection capability is maintained, but device complexity and cost increase

Engineering Contradiction:
Improvedetection capabilityVSAvoidmonitoring system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent transforms the physical state (pressure) of the gas sample to match the operating requirements of standard gas analyzers, allowing the use of conventional, simpler, and more cost-effective detection equipment rather than specialized low-pressure measurement systems

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent extracts a small gas sample from the thermally insulating barrier through a sampling line, separating the detection function from the main pressurized system, and analyzes it externally after pressure adjustment, simplifying the overall monitoring system design

Inventive Principle:
Principle #2Taking out (Extraction)

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 approach enables effective detection of combustible gases in the thermally insulating barrier, reducing costs and improving efficiency by allowing analysis of low-pressure gas phases, thereby enhancing safety and operational reliability of the tank monitoring system.

Implementation Method 1

sampling means for sampling a gas phase present in said thermally insulating barrier under said negative pressure

Methodology Applied
Scientific EffectPressure gradient: Pressure Gradient

Implementation Method 2

a device for adding a measured quantity of inert gas to said sampled gas phase so as to raise the pressure thereof to an operating pressure of a gas analyzer

Methodology Applied
Scientific EffectGas compression: Compression

Implementation Method 3

measuring a concentration of the combustible gas in said diluted gas sample with the gas analyzer

Methodology Applied
Scientific EffectGas analysis:

Implementation Method 4

a thermally insulating barrier placed between the sealing membrane and the bearing wall, the thermally insulating barrier comprising insulating solid materials and a gaseous phase maintained under negative relative pressure

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Data Source

PatentEP3074744B1Monitoring of a sealed and thermally insulated vat
Publication Date: 2019.10.23 GAZTRANSPORT & TECHNIGAZ SA
  • EP3074744B1 patent drawingFigure 1
  • EP3074744B1 patent drawingFigure 2~7
  • EP3074744B1 patent drawingFigure 3~4

AI summary

The invention relates to a method for monitoring a sealed and thermally insulated vat (1) intended to hold a fuel gas that is liquefied at low temperature, in which a wall of the vat comprises a thermally insulated barrier (3) arranged between the sealing membrane and the bearing wall, the thermally insulated barrier comprising solid insulation materials and a gas phase maintained at a negative relative pressure, the method comprising: obtaining a diluted gas sample by collecting a sample of the gaseous phase at the negative relative pressure in the thermally insulated barrier through a collection tube (11) and by the addition of a controlled quantity of an inert gas to the gaseous phase to be collected or that has been collected, raising the pressure of the diluted gas sample to an operating pressure of a gas analyzer (25), and measuring a concentration of the fuel gas in the diluted gas sample with the gas analyzer.