Optical Anionic Charge Detection in Process Streams

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Solution Overview

Problem

Existing methods for determining anionic groups in streams are labor-intensive, require separate sample collection, and are not suitable for direct measurement in flowing streams, often relying on single-wavelength measurements that are sensitive to interference and necessitate time-consuming calibration for each sample type.

Innovation Solution

A method and device utilizing light absorption measurement of a cationic dye added to the stream, based on the Beer-Lambert Law, allowing direct measurement of anionic charge in flowing streams without separate sample collection, using a single calibration curve for different particle fractions and enabling simultaneous turbidity calculation from the same absorption spectrum.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional titration methods are used to measure anionic groups, then measurement accuracy is improved, but measurement time and operational complexity increase significantly

Engineering Contradiction:
Improveanionic group measurement accuracyVSAvoidmeasurement time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces manual titration operations with an automated optical measurement system. A flow cell continuously measures light absorption at multiple wavelengths as the stream passes through, eliminating the need for manual sample collection, titration, and calculation. The system automatically determines anionic charge concentration from the multi-wavelength absorption data, significantly reducing measurement time while maintaining accuracy.

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

Solution Approach 2:

The measurement system operates continuously by measuring light absorption through the flowing stream in real-time. Multiple wavelengths are measured simultaneously as the stream flows through the cell, enabling continuous monitoring without interrupting the process flow. This continuous operation eliminates the batch-wise nature of traditional titration methods.

Inventive Principle:
Principle #20Continuity of useful action

2Device complexity

If single-wavelength optical measurement is used, then device complexity is reduced, but measurement reliability deteriorates due to interference sensitivity

Engineering Contradiction:
Improvemeasurement system complexityVSAvoidcharge determination reliability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent divides the optical measurement into multiple wavelength segments. Instead of using a single wavelength, the system measures absorption at multiple discrete wavelengths (e.g., 430nm, 480nm, 530nm, 580nm, 630nm) simultaneously. This segmentation allows the system to distinguish between dye absorption and interference from turbidity or other stream components, improving reliability while keeping each individual wavelength measurement simple.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The multi-wavelength measurement system serves multiple functions: it determines anionic charge concentration, compensates for turbidity interference, and can potentially identify different types of anionic groups. By making the measurement system multi-functional through wavelength diversity, the patent improves reliability without proportionally increasing complexity.

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

3Measurement precision

If separate sample collection is performed, then measurement precision is improved through controlled conditions, but productivity decreases due to additional handling steps

Engineering Contradiction:
Improveanionic group determination accuracyVSAvoidmeasurement throughput
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent merges the sample handling function with the measurement function. The stream flows continuously through the measurement cell without being diverted into separate collection vessels. The measurement occurs in-line as the stream passes through the flow cell, combining the transportation and measurement operations into a single continuous process, thereby improving productivity while maintaining measurement quality.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The flowing stream serves its own measurement function without requiring external sample collection and preparation. As the stream flows through the cell, it automatically presents itself for optical measurement at multiple wavelengths. The continuous flow provides both the sample delivery mechanism and the measurement target, eliminating redundant handling steps.

Inventive Principle:
Principle #25Self-service

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 provides a fast, simple, and reliable method for determining anionic charge in streams, enabling on-line analysis without pretreatment, reducing interference from turbidity, and allowing monitoring of chemical performance in processes like paper manufacturing.

Implementation Method 1

measuring a light absorption or transmittance spectrum of the stream

Methodology Applied
Scientific EffectLight absorption: Absorption (EM radiation)

Implementation Method 2

adding a cationic dye to the stream

Methodology Applied
Scientific EffectAdsorption: Adsorption

Data Source

PatentEP3071947B1Optical determination of anionic charge in a process stream
Publication Date: 2023.03.29 KEMIRA OY
  • EP3071947B1 patent drawingFigure 1~2
  • EP3071947B1 patent drawingFigure 3~4
  • EP3071947B1 patent drawingFigure 5~6

AI summary

The present invention concerns a method of optical measurement of an aqueous stream, and of processing the results of the measurement in order to determine the anionic charge of the stream, the method being carried out by measuring the light absorption of the stream and predicting the amount of anionic groups in the stream using a mathematical processing, such as mathematical calculations. Particularly, the method includes the steps of adding an amount of a cationic dye to the aqueous stream, measuring the light absorption spectra of the obtained dye-containing stream, and processing the obtained light absorption spectrum using said mathematical processing in order to obtain the anionic charge. The invention also concerns the use of the obtained spectrum in determining the turbidity of the stream, as well as a device suitable for use in carrying out the method.