Compressed Air Leakage Detection via Pressure Decay

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Solution Overview

Problem

Current compressed air systems lack automated procedures for detecting leakage levels, leading to energy inefficiencies and unnecessary maintenance costs, as they rely on manual methods that are time-consuming and not cost-effective.

Innovation Solution

A method utilizing a frequency converter and pressure sensor to estimate the leakage level in compressed air systems by measuring pressure decay and calculating the system's volume, allowing for periodic determination of leakage without additional components, and using the frequency converter to perform calculations based on gathered data.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If manual methods are used to detect leakage levels, then detection can be performed, but the process is time-consuming and not cost-effective

Engineering Contradiction:
Improvedetection speedVSAvoidtime for maintenance measures
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The system uses existing components (frequency converter and pressure sensor) to automatically detect leakage levels without requiring external detection devices or manual intervention. The frequency converter self-measures motor parameters while the pressure sensor continuously monitors system pressure, enabling the system to self-diagnose leakage conditions.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces manual detection methods with automated electronic measurement and calculation. The frequency converter electronically measures motor current, voltage, and power to calculate volumetric flow rate, while the pressure sensor provides electronic pressure data, substituting mechanical/manual leakage detection with automated computational analysis.

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

2Extent of automation

If automated leakage detection is implemented, then detection efficiency improves, but additional components and hardware costs increase

Engineering Contradiction:
Improveautomated leakage detectionVSAvoidnumber of components
Core Design Contradiction:
Extent of automationVSDevice complexity

Solution Approach 1:

The frequency converter performs multiple functions: it controls the compressor motor, measures electrical parameters (current, voltage, power), calculates volumetric flow rate, and provides data for leakage detection. The pressure sensor serves dual purposes by monitoring both system pressure for operational control and pressure decay for leakage detection.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The existing frequency converter and pressure sensor, already present in the compressed air system for operational control, are utilized for leakage detection without requiring additional dedicated detection hardware. The system leverages data from components already performing their primary functions.

Inventive Principle:
Principle #25Self-service

3Measurement precision

If leakage detection accuracy is improved, then energy savings potential is maximized, but measurement precision requirements increase system complexity

Engineering Contradiction:
Improveleakage level detection accuracyVSAvoidcalculation complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The system continuously monitors pressure decay over time and compares it against expected pressure profiles to determine leakage levels. The frequency converter continuously calculates volumetric flow rate based on real-time electrical measurements, providing ongoing feedback about system performance and leakage conditions.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent replaces complex physical measurement devices with computational methods. Instead of using specialized flow meters or leakage detection instruments, the system uses mathematical calculations based on electrical parameters (power, current, voltage) and pressure measurements to determine volumetric flow rate and leakage levels.

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

Enables accurate and cost-effective detection of leakage levels, allowing for economic analysis and timely maintenance, reducing energy consumption and operational costs by identifying leaks without extra hardware, and providing a means to monitor leakage over time.

Implementation Method 1

measuring electrical values, in particular power, current and voltage, of the screw compressor (100) motor with the frequency converter (200)

Methodology Applied
Scientific EffectElectrical measurement: Ohm's Law

Implementation Method 2

measuring the system pressure of the compressed air system with the pressure sensor (300)

Methodology Applied
Scientific EffectPressure measurement: Pressure Gradient

Implementation Method 3

screw compressor (100) to produce a compressed air system pressure above atmospheric pressure level

Methodology Applied
Scientific EffectGas compression: Compression

Implementation Method 4

the volumetric flow rate produced by the compressor is nearly directly proportional to its rotational speed

Methodology Applied
Scientific EffectVolumetric compression: Boyle's Law

Implementation Method 5

letting the pressure to decrease from the compressed air system until the pressure falls to the first pressure limit

Methodology Applied
Scientific EffectPressure decay: Pressure Gradient

Data Source

PatentEP3409953B1Method in a compressed air system and related arrangement
Publication Date: 2020.12.23 ABB (SCHWEIZ) AG
  • EP3409953B1 patent drawingFigure 1
  • EP3409953B1 patent drawingFigure 2~3
  • EP3409953B1 patent drawingFigure 4~5(b)

AI summary

A method of determining leakage rate of a compressed air system having a pressure sensor and a screw compressor driven by a frequency converter. The method comprises setting a first pressure limit and a second pressure limit, increasing the pressure of the compressed air system with the screw compressor until the pressure of the compressed air system reaches the second pressure limit. During the increase of the pressure the rotational speed of the screw compressor is estimated and the system pressure is measured. The volume of the compressed air system is calculated from the determined rotational speed estimates and measured system pressures together with the stored timestamps and temperatures and pressures in the system at start and end of increase of the pressure and known constants. Further, the pressure is let to decrease to the first pressure limit, and the system pressure is measured at multiple of time instants during the decrease of the pressure. An exponential curve is fitted on the pressure measurement data and the pressure decay coefficient is used as a measure indicating the leaking condition of the compressed air system.