Application of laser diffraction in the detection of particles in liquid media

Why does delicious yogurt always have the same taste? Why does medical ointment always have the same effect? ​​All this is attributed to the size of their "droplets". The same size of droplets has a decisive influence on the taste of yogurt, the viscosity of medical ointment, etc. Therefore, manufacturers of these products also attach great importance to the size of particles in the liquid medium.

For manufacturers, product monitoring during the production of process equipment is very important. The production process monitoring of process equipment also provides manufacturers with the following advantages: real-time detection data can be collected in a timely manner and real-time detection data can be fed back to the main control system of the process equipment in a timely manner. This is the best solution for comparing the quality of products from different production batches. At the same time, this real-time detection can also reduce waste in the production of process equipment, reduce energy consumption of equipment, and extend the service life of equipment. In the process production process of powdery raw materials, quality monitoring methods have been used for a long time; in the process production process of liquid media, such as suspended liquid products, emulsified liquid products and mud products, there are also online LPS detection instruments for real-time monitoring of droplet particle size.

Application of laser diffraction

The working principle of the LPS droplet size detection method is laser diffraction. The raw materials to be detected flow continuously through the detection area. The solid particles or droplets to be detected produce certain scattering fringes and diffraction fringes. The detection instrument detects and analyzes these fringes and calculates the size of the particles or droplets based on them.

When the particle concentration in the detected medium is high, the multi-scattering method can be used for detection to reduce the influence on the average particle size detection. The influence of the particle concentration in the medium is automatically corrected by the software in the detection system. Therefore, the system can realize on-site detection of process equipment and can detect medium particles with a concentration of 10,000 ppm. In many process technologies, the uniformity of particle size is an important process control parameter. Therefore, the real-time detection value of this detection system is closely related to time and represents the function of particle change over time. The detection control software used by the system can classify and store these data by date and transmit data to a higher-level control system.

When the concentration of the detected particles reaches 10,000 ppm, the detection area of ​​the instrument can also be detected without any problems. The laser diffractometer can be directly installed on the homogenizer diluter or a component of the process equipment. If the viscosity of the emulsion or mud medium to be detected is large, certain processing skills are required to ensure accurate detection results.

In the online detection of liquid medium particles, the raw materials to be detected flow continuously through the detection area.
The solid particles or droplets to be detected will produce certain scattering fringes and diffraction fringes.

Dilution scheme

When the viscosity of the medium to be tested is high, it must be diluted before testing. An efficient dilution system should have repeatable dilution to ensure that the results of each dilution are the same; and the required maintenance should be as little as possible. To achieve this goal, the following two schemes can be adopted:

- If continuous testing is required from the process technology point of view, and the dilution multiple is less than 1:1000, a homogenizer diluter can be used. It combines the functions of pumping, dilution and output in one.

- If the concentration of the medium is too high or the working pressure of the process equipment is too high, continuous sampling is not possible. At this time, another solution is required: sampling with a rotary sampler. The purpose is to take test samples intermittently from the production process. In a continuous stirring and mixing container, these test samples are diluted, the stirring diluent is added, and finally they are tested. If further dilution is required, homogenizer dilution can be performed again.

The Insitec LPS Liquid Medium Particle Detector continuously and in real time detects the particle and droplet size of products in process equipment production processes,
such as suspended liquid products, emulsions and slurries.

Reliable repeatability

In the above sampling methods, users are concerned about whether each sampling is the same and how accurate the repeatability of each sampling is. Therefore, the dilution system must be able to prove that the data of each particle detection is stable. In the multiple detection tests on the diluted slurry, it is also proved that the dilution degree has no effect on the detection value of the particle size, which means that the dilution process can achieve high repeatability.

The liquid medium particle detector is designed for continuous real-time detection. Each component of the system can be configured according to the actual process equipment.

The modular structure improves the flexibility of instrument manufacturing .

The Malvern LPS liquid medium particle detector is a continuous, online liquid particle detection instrument. Each of its components: sampler, primary diluter, homogenizer diluter, detector and control software, etc., can be individually configured according to the specific production process.

The sampler of the LPS liquid medium particle detector takes out a 2.5mm length of medium from the process equipment pipeline as a test sample each time. The flow of the liquid medium will not be interrupted during the sampling process, so as to avoid the blockage of the pipeline flow. If necessary, such as when the pressure in the process equipment pipeline is very high, sampling can be carried out using a dedicated interface. Its primary diluter and homogenizing diluter work together to prepare the best test sample for the detection of liquid medium particles. These parts have only a small movement distance, can be automatically cleaned, and can ensure the use of minimal diluent. The

core component of the system is the Insitec particle analyzer, which has the advantages of laser diffraction technology, no calibration and low maintenance. This detection system has a wear-resistant, self-cleaning detection observation window, and compressed air can be used to avoid condensation on the observation window.