scraped film evaporatorIt is a heating steam jacket on the outside of the shell, and a rotatable scraper on the inside, which is driven by a rotating shaft in the center of the cylinder. After the raw material liquid is added tangentially from the upper part of the evaporator, driven by gravity and rotating scraper, a downward rotating film is formed along the inner wall surface of the shell. The finished liquid is discharged from the bottom of the ejector, and the secondary steam is discharged from the upper part after the demister. The outstanding advantage of this evaporator is that it has strong adaptability to materials, and is suitable for evaporation of high viscosity, easy crystallization, easy scaling, suspended solids or heat-sensitive feed liquid.

It is mainly composed of heating jacket and scraper, heating steam through the jacket, scraper mounted on a rotatable shaft, scraper and heating jacket wall to maintain a small gap, usually 0.5~1.5mm. After preheating, the feed liquid is added along the tangential direction from the upper part of the evaporator. Under the action of gravity and rotating scraper, it is distributed on the inner wall to form a downward rotating film, and is continuously evaporated and concentrated during the descending process. The finished liquid is discharged from the bottom and the secondary steam escapes from the top. In some cases, such an evaporator can be used to evaporate the solution to dryness to obtain a solid product directly at the bottom.

Performance characteristics:

1. Vacuum pressure drop is small:

Material vaporization gas from the heating surface to the external condenser, there is a certain pressure difference. In typical evaporators, this pressure drop (Δp) is usually relatively high and sometimes even unacceptably high. The scraper film evaporator has a large gas through the space, the pressure in the evaporator can be seen as almost equal to the pressure in the condenser, so the pressure drop is very small, and the vacuum degree can reach 5mmHg.

2. Low operating temperature:

Due to the above characteristics, the evaporation process can be maintained at a high degree of vacuum. Due to the increase of vacuum degree, the boiling point of the corresponding material decreases rapidly, so the operation can be carried out at a lower temperature, which reduces the thermal decomposition of the product.

3. Short heating time:

Due to the unique structure of the scraper film evaporator, the scraper has a pumping effect, making the material in the evaporator residence time is very short; in addition, the heated evaporator due to the high-speed turbulence of the film makes the product will not stay in the evaporator surface. Therefore, it is particularly suitable for the evaporation of heat-sensitive materials.

4. High evaporation strength:

The reduction of the boiling point of the material increases the temperature difference with the heat medium; the function of the film scraper reduces the thickness of the liquid film in the turbulent state and reduces the thermal resistance. At the same time, in this process, the material is inhibited from forming walls and scaling on the heating surface, and is accompanied by good heat exchange, so the total heat transfer coefficient of the scraped film evaporator is improved.

5. Large operation elasticity:

It is precisely because of the unique performance of the scraped film evaporator that it is suitable for handling heat-sensitive and requires smooth evaporation, high viscosity and a sharp increase in viscosity with the increase of concentration, and its evaporation process can also be smoothly evaporated. It can also be successfully applied to the evaporation and distillation of materials containing solid particles, crystallization, polymerization, fouling, etc.

6. Adapt to a wide range of viscosity changes, high and low viscosity can be processed, and the material viscosity can be as high as 100000 centipoise (CP).

7. The inner wall of the evaporation section cylinder is precisely bored and polished, and the surface is not easy to produce coking and scaling.

8. Easy to operate, easy to adjust product indicators, under closed conditions, can be controlled for continuous production.

9. The equipment covers an area of small, simple structure, convenient maintenance, easy cleaning.