TD 1H-NMR Slurry Catalyst Solids Content Measurement
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Solution Overview
Problem
In gas-phase fluidized bed polymerization processes, accurately measuring the solids content in slurry catalyst compositions is challenging due to uncertainties in volumetric flow measurements and variations in catalyst composition, which can result in inconsistent polymer product properties.
Innovation Solution
A method using time-domain 1H-nuclear magnetic resonance (TD 1H-NMR) spectroscopy to rapidly and accurately determine the percent solids content (PSC) of solids in slurry catalyst compositions by measuring voltage signals from both the slurry catalyst and its suspension liquid, without the need for calibration standards, allowing for precise calculation of PSC using Equation I.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If volumetric flowmeters are used to measure slurry catalyst flow, then the measurement process is simple and continuous, but the measurement precision deteriorates due to uncertainties in temperature, pressure compensation and flow variations
Solution Approach 1:
The patent replaces mechanical/volumetric flow measurement systems with time-domain NMR spectroscopy, a physical-chemical analysis method. The NMR technique measures the actual solids content directly through nuclear magnetic resonance signals, eliminating the need for temperature and pressure compensation calculations inherent in volumetric flowmeters. This substitution provides both continuous measurement capability and high precision by directly detecting the physical state of the slurry catalyst.
2Ease of manufacture
If conventional measurement methods are used, then the measurement process is simple, but the measurement precision deteriorates with 10-15% error
Solution Approach 1:
The patent replaces conventional volumetric and gravimetric measurement methods with time-domain NMR spectroscopy. The NMR method provides 1% or better accuracy by directly measuring the nuclear magnetic resonance signals of hydrogen atoms in the slurry catalyst, distinguishing between solid and liquid phases based on their different relaxation times. This eliminates the cumulative errors from multiple separate measurements required by conventional methods.
3Adaptability or versatility
If slurry catalyst composition varies, then adaptability to different batches is improved, but manufacturing precision deteriorates as polymer properties become inconsistent
Solution Approach 1:
The patent implements a feedback mechanism by using time-domain NMR to precisely measure the actual solids content of each slurry catalyst batch. This measurement feeds back to the control system, which then adjusts the slurry catalyst feed rate to maintain the desired catalyst dosage. This closed-loop control compensates for batch-to-batch variations in slurry composition, ensuring consistent polymer product properties despite variations in incoming catalyst batches.
Solution Approach 2:
The patent changes the measurement parameter from indirect volumetric flow measurement to direct physical-chemical analysis using NMR spectroscopy. By measuring the actual solids content through NMR relaxation time differences between solid and liquid phases, the system can detect and compensate for compositional variations in each batch, maintaining manufacturing precision while adapting to different slurry catalyst formulations.
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 method provides an accuracy of less than 1% relative error, significantly improving upon conventional methods which often have 10-15% error, and is applicable for solids content ranging from 10% to 50% by mass, enabling consistent polymer production across different batches.
Implementation Method 1
A first time domain 1H-nuclear magnetic resonance (TD 1H-NMR) spectrum is obtained using a time domain (TD)-NMR spectrometer and the test sample of the slurry catalyst composition
Data Source
AI summary
The present disclosure provides a method of measuring a percent solids content (PSC) of solids by mass in a slurry catalyst composition, where the solids include a catalyst. The method includes obtaining a first time domain (TD) 1H-nuclear magnetic resonance (NMR) spectrum using a time domain (TD)-NMR spectrometer and a test sample of the slurry catalyst composition from which a value of a voltage signal (a) that represents the slurry catalyst composition is determined. A second TD 1H-NMR spectrum using the TD NMR spectrometer is obtained for a neat sample of the suspension liquid for the solids of the slurry catalyst composition, where a value of a voltage signal (b) from the second TD 1H-NMR spectrum that represents the suspension liquid for the solids of the slurry catalyst composition is determined. The percent solids content (PSC) of solids in a slurry catalyst composition is then determined with Equation I: PSC=(1−a/b×db/da)×100% Equation I where x represents mathematical multiplication, a and b are as described above, db is a density of the suspension liquid for the solids of the slurry catalyst composition and da is a density of the slurry catalyst composition.