Nylon Salt Solution Preparation With Online Molar Ratio Control
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Solution Overview
Problem
Existing batch salt processes for nylon production face challenges in achieving consistent molar ratios of dicarboxylic acid to diamine, particularly in large-scale industrial settings, due to errors in volumetric metering and oxidation issues, which affect molecular weight and dyeability.
Innovation Solution
A continuous preparation process using a suspension preparation device, high-shear pump, and online near-infrared monitoring equipment to form a nylon salt solution, ensuring precise molar ratios and minimizing oxidation risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If batch salt processes are used with continuous sampling and testing to monitor molar ratio, then molar balance can be achieved, but the process is not suitable for large-scale industrial production and lacks productivity
Solution Approach 1:
The patent replaces the mechanical batch sampling and testing system with an online near-infrared monitoring system that continuously measures molar ratio in the salt solution without requiring physical sampling. This substitution enables real-time monitoring suitable for large-scale continuous industrial production while maintaining measurement precision.
Solution Approach 2:
The patent implements continuous salt formation process with continuous online monitoring, eliminating the discontinuous batch operation. The salt solution is continuously circulated through the reactor while the near-infrared sensor continuously measures molar ratio, enabling both high productivity and precise control suitable for industrial scale.
2Ease of manufacture
If conventional volumetric metering methods are used to meter aliphatic dicarboxylic acid, then the process is simple, but significant metering errors occur due to wide particle size distribution and varying bulk density
Solution Approach 1:
The patent replaces conventional volumetric metering mechanisms with a suspension preparation system that uses high-shear mixing and online near-infrared monitoring. This substitution eliminates the metering errors caused by particle size distribution and bulk density variations by directly measuring the actual concentration in the suspension.
Solution Approach 2:
The patent implements feedback control by using online near-infrared monitoring to continuously measure the molar ratio in the salt solution and adjust the feeding rates of dicarboxylic acid and diamine accordingly. This feedback mechanism compensates for metering errors and ensures precise molar ratio control.
3Device complexity
If batch processing with manual sampling is used, then equipment complexity is low, but measurement errors and oxidation risks increase in large-scale production
Solution Approach 1:
The patent replaces manual sampling and simple equipment with an automated suspension preparation system featuring high-shear mixing, online near-infrared monitoring, and automated feedback control. This increases equipment complexity but significantly improves reliability by eliminating manual intervention errors and oxidation risks through continuous protected processing.
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 process achieves precise molar ratios with minimal measurement errors and reduces oxidation, enhancing the quality and consistency of the nylon salt solution for polymerization.
Implementation Method 1
a high-shear pump and a mixing reactor provided with a water inlet pipe, which are sequentially connected with and in communication with each other. The high-shear pump and the mixing reactor are cyclically connected with and in communication with each other through two connecting pipelines. The aliphatic dicarboxylic acid is capable of circulating with a water between the high-shear pump and the mixing reactor to form an aliphatic dicarboxylic acid suspension.
Implementation Method 2
The second salt formation reactor further includes a circulation pipeline of the second salt formation reactor, and the circulation pipeline of the second salt formation reactor is provided with an online near-infrared monitoring equipment. The online near-infrared monitoring equipment is configured for monitoring a molar ratio of the aliphatic dicarboxylic acid to the diamine in the nylon salt solution
Data Source
AI summary
A preparation equipment and a process for a nylon salt solution. The preparation equipment includes a suspension preparation device, a first salt formation reactor and a second salt formation reactor. The suspension preparation device includes a feeding unit, a continuous feeding unit, a high-shear pump and a mixing reactor, the high-shear pump and the mixing reactor are cyclically connected with and in communication with each other through two connecting pipelines; the second salt formation reactor includes a second diamine feed pipe, a third diamine feed pipe, a circulation pipeline of the second salt formation reactor and an online near-infrared monitoring equipment located on the circulation pipeline of the second salt formation reactor.