Due to different materials, the type of scraper used in the scraper evaporator will be changed accordingly. The three commonly used types of scraper evaporators are hinge scraper, sliding scraper, and fixed scraper. Due to the different types, their functions in the scraper evaporator are also different.
Taking the hinged scraper as an example, it is suitable for materials that are easy to foul on the heating surface. The scraper is usually made of metal parts, and the scraper is installed on the rotating frame by means of living hinges. When the rotor rotates, due to the centrifugal force, the scraper is pressed against the inner wall of the evaporation cylinder and slides on the wall at a certain angle (to the wall) to scrape the material into a film and prevent the wall from scaling.
The sliding scraper is a basic and common form of scraper. The scraper is installed in the four scraper guide grooves of the scraper evaporator rotor, and is thrown radially toward the inner wall of the evaporator cylinder due to the centrifugal force of the rotor rotation, and at the same time makes a circular motion with the rotor. The scraping of the scraper makes the material appear in a film-like turbulent state on the evaporation wall, which greatly improves the heat transfer coefficient. At the same time, this continuous scraping effectively suppresses the phenomenon of overheating, dry wall and fouling of the material. .
Usually, the scraper of this kind of scraper evaporator is made of filled PTFE, which is suitable for working temperature below 150℃; when the evaporation temperature is higher than 150℃, carbon fiber material is required. The end surface of the scraper is processed with a liquid guiding groove at a certain angle.
There is also the fixed scraper of the scraper evaporator, which is made of metal materials. It is rigidly connected to the rotor. The length of the scraper is the same as that of the evaporation cylinder. The gap between the rotating scraper and the inner wall of the evaporation cylinder is only 1-2mm. It requires high processing and installation accuracy, and it is suitable for the evaporation, concentration, desolvation or purification of ultra-high viscosity and easy-to-foam materials.
