Scraper Thin Film Evaporator

                                                  Introduction of Scraper Thin Film Evaporator 

1. Overview :

Scraper evaporator, it is a new type of evaporator with strong adaptability, such as high viscosity, heat sensitivity and easy crystallization, scaling materials are suitable. It is mainly composed of a heating jacket and a scraper, the jacket through the heating steam, the scraper is installed on the rotating shaft, the scraper and the heating jacket inner wall to maintain a small gap, usually 0.5~1.5 mm. After preheating, the material liquid is added by the upper part of the evaporator along the tangential direction. Under the action of gravity and rotating scraper, the material liquid is distributed in the inner wall to form a backspin film, and it is continuously evaporated and concentrated in the process of falling. The liquid is discharged from the bottom and the secondary steam escapes from the top. In some cases, this evaporator can steam the solution to get a solid product directly at the bottom.

2. Working principle:

The material enters the film evaporator radially from above the heating zone; The distributor is distributed to the heating wall of the evaporator, and then the rotating film scraper continuously and evenly scrapes the material into a thick and thin liquid film on the heating surface, and pushes it downward in a spiral shape. In this process, the rotating film scraper ensures that the continuous and uniform liquid film produces high-speed turbulence, and prevents the liquid film from coking and scaling on the heating surface, thereby improving the total transfer coefficient. The light components are evaporated to form steam flow, which reaches the external condenser directly connected with the evaporator through the vapor-liquid separator. The recombination is discharged from a cone at the bottom of the evaporator.

3. Performance characteristics:

1) Low vacuum pressure 

2) Low operating temperature

3) Short heating time

4) High evaporation intensity

5) High flexibility in operation

4. Application scope:

Scraper evaporator is widely used in petroleum, chemical, pharmaceutical and other industries, especially suitable for high viscosity (such as tannin extract, honey, etc.) and easy crystallization, scaling, heat sensitive materials.

5. Component:

1) Motor, reducer  

It is the driving device of the rotor rotation. The speed of rotation of the rotor will depend on the form of the scraper. The viscosity of the material and the inner diameter of the evaporation cylinder; Choosing the appropriate linear speed of the scraper is one of the important parameters to ensure the stable and reliable operation of the evaporator and satisfactory evaporation effect.

2) Separating cylinder

The material enters the evaporator tangentially from the entrance at the lower end of the separation cylinder body, and is distributed continuously and evenly on the inner wall of the evaporation cylinder through the distributor installed in the separation cylinder body. The secondary steam evaporating from the evaporation cylinder body rises to the separation cylinder, and the droplets or foam that may be carried by the secondary steam are separated through the gas-liquid separator installed in the cylinder. The secondary steam is extracted from the upper end of the evaporator.

3) Distributor

The distributor is mounted on the rotor. Reasonable design, so that the material entering the evaporator from the tangential direction, through the rotating distributor, is continuously and evenly distributed on the film on the evaporation surface.

4) Gas-liquid separator

The rotary plate gas-liquid separator is installed above the separation cylinder, which traps the droplets or foam that may be carried by the rising secondary steam and brings them back to the evaporation surface.

5) Evaporation cylinder body

Also known as heating cylinder body. It is the evaporation surface of heat exchange between the material forced into film by the rotary scraper and the heating medium in the jacket. The inner diameter and length of the cylinder body are determined by the evaporation area and the appropriate length-diameter ratio.

The inner wall of the heating cylinder body is processed and polished by a special machine tool, and the connecting surface of both ends of the flange is processed once to ensure the overall centrality of the equipment. After polishing (mirror polishing if necessary), the inner wall of the cylinder body is smooth and bright, and it is not easy to stick and scale, which effectively ensures the high heat transfer coefficient of the equipment.

6) Rotor

The rotor installed in the evaporator cylinder is composed of a rotating shaft and a rotating frame. The rotor is driven by motor and reducer, and drives the scraper to make circular motion. The rotating frame is made of stainless steel precision castings, so that its strength, geometric size and stability are effectively guaranteed.

7) Scraper

Due to the movement of the scraper, the material is continuously scraped into a film on the evaporation surface to achieve the effect of film evaporation.

6. Technical parameter: