A scraper evaporator is a high - efficiency evaporation device based on mechanical film - forming technology. It is specifically designed for processing materials with high viscosity, thermal sensitivity, and those prone to crystallization and scaling. Its unique working mode and structural characteristics make it a key process equipment in industries such as chemical engineering, pharmaceuticals, and food processing.

 

Core Structure and Working Principle

1. Mechanical Film - forming System: The core of the equipment consists of a heating jacket and high - speed rotating scrapers. The scrapers maintain a precise gap of 0.5 - 1.5 mm with the inner wall of the jacket. After the material is introduced through the top tangentially or via a throwing disk, it forms a uniform film under the action of gravity and centrifugal force. The rotating scrapers continuously scrape the heating surface to prevent scaling and enhance heat transfer.

2. Multi - stage Separation Design: A gas - liquid separator is installed in the separation cylinder to ensure that there are no liquid droplets remaining in the secondary steam, thereby improving the evaporation purity. The concentrated liquid is discharged from the bottom, and the steam escapes from the top. Some models can even dry the material to directly produce solid finished products.

3. Power Drive Module: The motor and reducer work together to control the rotation speed of the scrapers. The linear speed (usually 1.5 - 3 kW/㎡) can be adjusted according to the material viscosity and evaporation requirements to balance the evaporation efficiency and energy consumption.

 

Technical Advantages and Performance Parameters

1. High - efficiency Heat Transfer Capacity: The thin - film process significantly increases the heat transfer coefficient. The evaporation intensity can reach 200 kg/㎡·h, making it particularly suitable for the rapid processing of materials such as organic solvents and aqueous solutions.

2. Short - time and Low - temperature Evaporation: The material residence time is only 5 - 10 seconds. With the vacuum system, low - temperature operation (usually below 60℃) can be achieved, perfectly protecting thermally sensitive components such as active substances in pharmaceuticals and nutritional components in food.

3. Wide Viscosity Adaptability: It can process materials with a viscosity of up to 100,000 centipoise, including high - consistency fluids such as honey and resin. The groove angle of the scrapers can be adjusted to adapt to different working conditions.

4. Anti - coking and Easy Maintenance: The polished inner wall of the cylinder reduces the risk of coking. The quick - opening top cover and sight glass design facilitate rapid cleaning and process monitoring.

 

Typical Application Scenarios

- Chemical Industry: Devolatilization of high - viscosity resins, solvent recovery, and concentration of corrosive liquids.

- Pharmaceutical Industry: Low - temperature concentration of traditional Chinese medicine extracts and pre - treatment before antibiotic crystallization.

- Food Processing: Dehydration of fruit syrup and protein enrichment in dairy products.

- Environmental Protection Engineering: Reduction of industrial wastewater volume and recovery of valuable components in waste liquid.

 

Selection Considerations and Limitations

Summary of Advantages:

- The heat transfer efficiency is 40% - 69% higher than that of traditional evaporators.

- It supports continuous production and automatic control.

- The stainless - steel structure meets GMP and food - grade hygiene standards.

 

Usage Limitations:

- The high power demand leads to relatively high energy consumption costs.

- The scrapers and bearings need regular maintenance and replacement.

- The single - unit processing capacity is small, and multiple units need to be connected in parallel for large - scale projects.

 

By precisely matching the material characteristics with the process parameters, the scraper evaporator can significantly improve production efficiency and reduce the risk of thermal damage to products, making it an irreplaceable core equipment in the fields of fine chemical engineering and bioengineering.