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Тест на содержание серного порошка в масле (слабополевой ядерно-магнитный метод)
In the production process of chemical powders (например, сера), a certain amount of oil is added according to product quality and characteristic requirements to improve product performance and facilitate production and processing. Порошок также содержит влагу. The content of these liquids in the powder is an important parameter that affects the quality of the product. To ensure stable product quality, необходимы точные и быстрые измерения. The low-field nuclear magnetic field can quickly complete the oil and water content test, и процесс подготовки проб очень прост, which provides the possibility to realize the quality inspection and quality control in the industrial production process.
Introduction to traditional test methods:
The traditional method is to use solvent extraction method to detect the oil content in sulfur. The detection process is complicated, time-consuming, and requires professional and technical personnel to operate, и человеческая ошибка велика. Кроме того, экстракт является токсичным реагентом, which is harmful to the health and safety of the operator. There are hazards, and this method is becoming increasingly unacceptable in the industry.
The basic principle of sulfur powder oil content test (слабополевой ядерно-магнитный метод):
The spin echo sequence is used for measurement. Фигура 1 shows the spin echo sequence and the detected nuclear magnetic signal. Распад свободной индукции (ПИД) NMR signal was measured at t1 after the 90-degree radio frequency pulse. Currently, амплитуда сигнала (А1) пропорционален числу протонов H в двух жидких фазах (moisture and oil) образца.
После 180-градусного импульса, амплитуда обнаруженного сигнала спин-эха равна A2. В это время, the water signal has attenuated to 0, and A2 is only the oil signal. Поэтому, разница A1-A2 между двумя амплитудами сигнала пропорциональна содержанию воды в образце..
After calibration with a sample with known moisture and oil content, the unknown sample can be tested within 30 секунд до 3 минуты. Процесс тестирования быстрый и неразрушающий, and industrial online process testing can be realized.
Кроме того, compared with chemical methods, nuclear magnetic methods have better reproducibility, не требуют химических растворителей, and can be operated by untrained personnel.