NIR Probe Sampling Window Extraction for Fouling Reduction
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Solution Overview
Problem
Current methods for monitoring control parameters in polymerization reactions, especially in heterogeneous phases, face issues such as frequent maintenance due to fouling of sampling windows and interference with fluid dynamics, limiting the effectiveness of Near Infrared Spectroscopy (NIR) in providing continuous and reliable measurements.
Innovation Solution
Employing NIR reflectance spectroscopy with optical fiber probes that do not require immersion in the polymerization mixture, allowing for in-line monitoring with reduced fouling and minimal impact on reactor fluid dynamics, using a sampling window that is only in contact with the mixture, thus enabling continuous monitoring with reduced maintenance needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If transmittance or transflectance NIR spectroscopy is used with immersion probes, then in-line monitoring of control parameters is achieved, but the sampling windows become fouled by the viscous polymerization mixture requiring frequent cleaning
Solution Approach 1:
The invention extracts the sampling window from the immersion probe structure, allowing it to be separated from the optical fiber bundle. This enables the sampling window to be positioned externally where it can be easily accessed for cleaning or replacement without disturbing the entire probe assembly, thus resolving the maintenance frequency issue while preserving measurement accuracy
Solution Approach 2:
The invention introduces a separate sampling window as an intermediary component between the polymerization mixture and the optical fibers. This mediator allows the NIR radiation to interact with the mixture without requiring the optical fibers to be directly immersed, thereby reducing fouling of the critical measurement components
2Measurement precision
If a long metallic probe body is inserted into the reactor to immerse the measurement head, then continuous in-line monitoring is enabled, but the probe interferes with the fluid dynamics of the polymerization reaction
Solution Approach 1:
The invention extracts the measurement head from the long metallic probe body, allowing the optical fibers to be positioned through a short insertion rather than requiring a 20cm protruding body. This minimizes the physical presence in the reactor, thereby reducing interference with fluid dynamics while maintaining continuous monitoring capability
Solution Approach 2:
The invention replaces the mechanical immersion probe structure with an optical fiber-based system that can transmit NIR radiation through a minimal insertion point. This substitution eliminates the need for a large metallic body in the reactor, thus preserving fluid dynamics while enabling continuous optical measurement
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 allows for reliable and continuous monitoring of control parameters like particle size and conversion degree, reducing fouling issues and maintaining reactor fluid dynamics, enabling up to 100 polymerization cycles without probe cleaning, and providing accurate predictions of polymer properties.
Implementation Method 1
monitoring techniques based on Near Infrared Spectroscopy (NIR) are receiving increasing attention, as they allow the above parameters to be rapidly and precisely measured in-line
Implementation Method 2
collects the light radiation scattered by the reaction mixture - created by the effect of irradiation with the incident radiation
Implementation Method 3
In 'in transflectance' spectroscopy, the radiation analyzed by the spectrophotometer is the fraction of incident radiation which, after passing through the sample, is reflected by a specific reflecting screen situated in the measurement cavity along the pathway of the radiation
Data Source
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AI summary
The present invention relates to a method for monitoring a control parameter of a polymerization reaction mixture in heterogeneous phase comprising the following steps: (a) acquiring at least one NIR reflectance spectrum of said mixture; (b) calculating a value of said control parameter by means of a calibration curve which correlates the NIR reflectance spectrum with the values of said control parameter measured with a reference measurement method. The present invention also relates to an apparatus for implementing said method.