Continuous Neutralization Control Using NIR Spectroscopy
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Solution Overview
Problem
Existing neutralization processes for producing water-absorbing polymers face challenges in maintaining consistent concentration of starting materials, leading to deviations in the degree of neutralization and polymer properties due to variations in sodium hydroxide content and residual water in pipe systems, which are not effectively accounted for in traditional batch-wise metering methods.
Innovation Solution
A continuous neutralization process where the content of components like sodium hydroxide or acrylic acid in the neutralization stream is continuously determined using methods such as NIR spectroscopy, allowing for real-time adjustment of the neutralization process to maintain desired concentrations, thereby ensuring consistent product quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If batch-wise metering of starting materials is used, then the process is simple to operate, but the concentration of starting materials varies leading to deviations in degree of neutralization
Solution Approach 1:
The patent implements continuous measurement of the degree of neutralization using NIR spectroscopy and feeds this information back to a control system that automatically adjusts the metering rates of acrylic acid and sodium hydroxide solution. This closed-loop feedback mechanism maintains precise control over the neutralization degree despite variations in starting material concentrations, resolving the contradiction between manufacturing precision and device complexity.
Solution Approach 2:
The patent replaces manual batch-wise metering with an automated continuous metering system controlled by electronic sensors and actuators. The NIR spectroscopy system substitutes visual inspection, and the automated control system replaces manual adjustment, thereby improving manufacturing precision while the complexity is managed through automation rather than manual intervention.
2Productivity
If sodium hydroxide solution is stored in pipe systems, then it is convenient for process continuity, but residual water in pipes causes concentration variations
Solution Approach 1:
The continuous NIR spectroscopy measurement system detects variations in sodium hydroxide concentration caused by residual water in pipe systems and feeds this information back to the control system. The controller automatically compensates for these variations by adjusting metering rates, thereby maintaining manufacturing precision while preserving process continuity through the pipe system storage arrangement.
Solution Approach 2:
The patent dynamically adjusts the metering parameters (flow rates) of starting materials based on real-time concentration measurements. When residual water dilutes the sodium hydroxide solution in the pipe system, the system increases the metering rate of sodium hydroxide to compensate, thereby maintaining the desired degree of neutralization despite concentration variations.
3Manufacturing precision
If continuous neutralization with real-time measurement is implemented, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent employs NIR (near-infrared) spectroscopy for continuous, non-contact measurement of the degree of neutralization, replacing traditional mechanical or chemical measurement methods. This optical measurement technique provides rapid, real-time data without requiring physical sampling or complex laboratory analysis, thereby improving manufacturing precision while keeping the added device complexity manageable through the use of established spectroscopic technology.
4Reliability
If metering is temperature-controlled to prevent overheating, then safety is improved, but process time increases
Solution Approach 1:
The patent implements continuous temperature monitoring with feedback control that dynamically adjusts the metering rates of acrylic acid and sodium hydroxide solution. When the temperature approaches unsafe levels, the system automatically reduces the metering rate to allow heat dissipation, and when temperature is safe, it increases the rate to maintain productivity. This real-time feedback mechanism ensures safety while minimizing process time extensions.
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 automatic correction of deviations in starting material concentrations, resulting in consistent quality of neutralized solutions and improved polymer properties by maintaining precise control over the neutralization process, reducing the risk of overheating and unwanted polymerization.
Implementation Method 1
the content of components like sodium hydroxide or acrylic acid in the neutralization stream is continuously determined using methods such as NIR spectroscopy
Implementation Method 2
at least one ethylenically unsaturated carboxylic acid is at least partially neutralized with a base... acrylic acid and sodium hydroxide solution are metered in simultaneously, so that a degree of neutralization of 75 to 100 mol % is maintained
Data Source
Figure 1
AI summary
The invention relates to a neutralization method which is characterized in that at least one ethylenically unsaturated carboxylic acid is at least partially neutralized with a base and at least one product flow of neutralization is continuously determined. The invention also relates to a device for carrying out said method.