Liquid Level Detection Device Using Filling Liquid to Reduce Temperature Errors

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Solution Overview

Problem

Liquid level detection errors occur in liquid supplying facilities due to rapid temperature changes and density variations of high-pressure gases during liquid discharge, as the temperature difference between the gas in the tank and the gas in the measurement pipe leads to inaccurate pressure readings.

Innovation Solution

A liquid level detection device with a differential pressure gauge and a filling liquid in the upper pipe to minimize temperature-induced errors, along with a temperature sensor to correct calculations, and using nitrogen gas as the high-pressure gas to prevent condensation and maintain detection accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If liquid level is detected using differential pressure in a pipe communicating with the gas-phase section during rapid liquid discharge, then liquid level measurement is achieved, but temperature difference between the gas in the tank and gas in the pipe causes measurement errors

Engineering Contradiction:

Improveliquid level detection accuracyVSAvoidtemperature difference between tank gas and pipe gas

Core Design Contradiction:

Measurement precisionVSTemperature

Solution Approach 1:

The patent introduces a filling liquid as an intermediary substance in the measurement pipe to replace the gas phase. This filling liquid transmits the pressure from the liquid phase in the tank to the differential pressure sensor without being affected by the rapid temperature changes that occur in the gas phase during rapid discharge, thereby eliminating temperature-induced measurement errors

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the physical parameter of the measurement medium from gas to liquid (filling liquid). Liquid has much lower compressibility and higher thermal inertia compared to gas, which stabilizes the pressure transmission and prevents the temperature difference effects that plague gas-based measurement systems during rapid discharge operations

Inventive Principle:

Principle #35Parameter changes

2Productivity

If high-pressure gas is used to discharge liquid rapidly, then discharge speed is improved, but condensation of the high-pressure gas causes detection errors

Engineering Contradiction:

Improveliquid discharge rateVSAvoidliquid level detection accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent uses nitrogen gas, an inert gas, to pressurize and discharge the liquid. Nitrogen has very low condensation tendency under the operating conditions, preventing the formation of liquid droplets or condensation that would interfere with the measurement system and cause detection errors while still providing the necessary pressure for rapid discharge

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

Solution Approach 2:

The filling liquid acts as a protective intermediary between the high-pressure gas environment and the measurement system. It isolates the measurement components from direct exposure to the high-pressure gas that might condense, allowing accurate measurements to be taken even during rapid discharge operations

Inventive Principle:

Principle #24Intermediary (Mediator)

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

Accurate liquid level detection and flow rate calculation are achieved by reducing temperature-related errors and preventing condensation, ensuring reliable operation during liquid discharge.

Implementation Method 1

a filling liquid 9 for filling at least a partial range inside the upper pipe 2a

Methodology Applied

Scientific EffectHydraulic pressure transmission: Pascal's Law

Implementation Method 2

a differential pressure gauge 2b for detecting a differential pressure between the lower pipe 2c and the upper pipe 2a

Methodology Applied

Scientific EffectDifferential pressure measurement:

Implementation Method 3

a liquid level calculation part 10 for calculating a liquid level of the tank 1 on the basis of a differential pressure detection result of the differential pressure gauge 2b

Methodology Applied

Scientific EffectHydrostatic pressure relationship:

Implementation Method 4

using nitrogen gas as the high-pressure gas to prevent condensation and maintain detection accuracy

Methodology Applied

Scientific EffectCondensation prevention:

Data Source

PatentUS10495495B2Liquid level detection device of liquid supplying facility, liquid level detection method of liquid supplying facility, and liquid supplying facility having the liquid level detection device

Publication Date: 2019.12.03 MITSUBISHI HEAVY IND LTD

AI summary

A liquid level detection device for a liquid supplying facility includes: a lower pipe which is in communication with a liquid-phase section of an interior space of a tank, the liquid-phase section being occupied by a liquid; an upper pipe which is in communication with a gas-phase section of the interior space of the tank, the gas-phase section being disposed above the liquid-phase section and occupied by a high-pressure gas; a differential pressure gauge for detecting a differential pressure between the lower pipe and the upper pipe; and a liquid level calculation part for calculating a liquid level of the tank on the basis of a differential pressure detection result of the differential pressure gauge. An inside of the upper pipe is filled with a filling liquid at least in a partial range.