Microwave Sensor Paper Pulp Thickness Measurement

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Solution Overview

Problem

Existing methods for measuring the thickness of paper pulp in papermaking machines are either costly due to the use of radioactive sources or unreliable in noisy environments, and existing sensors are cumbersome and do not provide sufficiently reliable measures.

Innovation Solution

A device equipped with a microwave sensor and a temperature sensor that uses frequency-response curves to measure the thickness of paper pulp, with a control unit for data processing and calibration, allowing for accurate and reliable measurements without the need for radioactive sources.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If GBS (Gamma Back Scattering) sensors are used to measure paper pulp thickness, then measurement accuracy is improved, but device cost and complexity increase due to requirement of radioactive sources

Engineering Contradiction:

Improvemeasurement accuracyVSAvoiddevice complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the radioactive source-based GBS sensing system with a microwave-based sensing system. The microwave sensor transmits electromagnetic waves through the paper pulp layer, and the reflected or transmitted signal characteristics are used to determine thickness. This substitution eliminates the need for radioactive sources while maintaining measurement capability, thereby reducing device complexity and cost.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the physical parameter used for measurement from gamma radiation backscattering to microwave electromagnetic wave propagation. By utilizing the frequency response of the material to microwave radiation, the system achieves thickness measurement without requiring radioactive sources, thus resolving the contradiction between accuracy and complexity.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If ultrasound sensors are used to measure paper pulp thickness, then device cost is reduced compared to GBS sensors, but reliability deteriorates in noisy environments

Engineering Contradiction:

Improvedevice costVSAvoidreliability in noisy environment

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent replaces the ultrasound sensing system with a microwave sensing system. Microwave sensors operate at higher frequencies and are less susceptible to electromagnetic interference and noise from the papermaking environment. The microwave sensor measures the frequency response of the material, providing reliable thickness measurements even in noisy industrial settings, thus resolving the contradiction between cost and reliability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Difficulty of detecting and measuring

If microwave sensors are used to estimate material consistency, then measurement capability is provided, but device size and reliability deteriorate

Engineering Contradiction:

Improvemeasurement capabilityVSAvoiddevice size

Core Design Contradiction:

Difficulty of detecting and measuringVSDevice complexity

Solution Approach 1:

The patent employs a compact microwave sensor design that integrates the transmission and reception of electromagnetic waves in a small form factor. The sensor measures the frequency response of the material by transmitting microwaves through the paper pulp layer and analyzing the reflected or transmitted signal characteristics. This approach provides reliable thickness measurement capability while maintaining a compact device size, resolving the contradiction between measurement capability and device size.

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

The device provides accurate and reliable measurements of paper pulp thickness, reducing costs and improving efficiency in noisy environments, while being easy to use and produce.

Implementation Method 1

Other sensors exploit microwaves, and in particular estimate the consistency of the material from the frequency response of the material itself

Methodology Applied

Scientific EffectMicrowave radiation: Microwave Radiation

Implementation Method 2

a temperature sensor (14)

Methodology Applied

Scientific EffectTemperature sensing:

Data Source

PatentUS8138769B2Method and device for measuring the thickness of a layer of material

Publication Date: 2012.03.20 GIUSEPPE CRISTINI

AI summary

Described herein is a method for measuring, via a microwave sensor, the thickness of a layer of first material, said method envisaging: acquiring at least one frequency response of the layer of first material via a microwave sensor; setting the microwave sensor on a plurality of specimens of second materials for different temperature values in such a way as to obtain reference data; calibrating the microwave sensor as a function of the electrical conductivity of the first material using the reference data; measuring the temperature of the layer of first material via a temperature sensor; determining measurement parameters from the frequency response; and processing the reference data with the measurement parameters to obtain a measurement of the thickness of the layer of first material.