A wiped film evaporator is a type of evaporator used for separation and concentration of liquids, particularly in the chemical and pharmaceutical industries. It consists of a cylindrical body and a rotor that rotates at high speed, creating a thin film of liquid on the inner surface of the cylinder.
The liquid to be evaporated is fed into the top of the evaporator and flows down the inside of the cylinder in a thin film. As the rotor rotates, it continually wipes the liquid film from the surface of the cylinder, creating turbulence and increasing the surface area of the liquid in contact with the heated surface of the cylinder.
The heat source can be provided by a variety of means, including steam, hot oil, or electric heaters. As the liquid is heated and evaporated, the vapor rises and is condensed on a cooled surface at the top of the evaporator. The condensed liquid is then collected and removed as the product.
The wiped film evaporator or thin film evaporator is particularly useful for processing heat-sensitive materials or materials that tend to form scales or deposits on heated surfaces. It can operate under vacuum conditions to lower the boiling point of the liquid and reduce the risk of thermal degradation or decomposition. In this blog post, we will take a closer look at wiped film evaporators, their design, operation, and applications.
Design of Wiped Film Evaporator:
Thin film evaporators are designed with a cylindrical body that houses the evaporation chamber. This chamber is typically heated by a jacket that is used to transfer heat to the process fluid. The evaporator is also equipped with a rotor that is used to wipe the film of the process fluid from the walls of the evaporation chamber. This rotor is typically driven by a motor that is connected to the top of the evaporator.
Principles of Wiped Film Evaporators:
The wiped film evaporator operates on the principle of separating components of a mixture based on their boiling points. It works by continuously feeding a mixture into the evaporator, where it comes into contact with the heated surface. The heat is transferred to the solution, and the components with the lowest boiling point will vaporize first.
The rotor then wipes the solution from the heated surface, creating a thin and uniform film that is in contact with the heat source, which promotes efficient heat transfer and vaporization. The vapor produced is then collected at the top of the evaporator, where it is condensed back into a liquid form and collected separately. The remaining solution is continuously fed into the evaporator, and the process is repeated until the desired level of separation or concentration is achieved.
Applications of Wiped or Thin Film Evaporator:
Wiped or Thin film evaporators are used in a wide range of applications, including:
- Food and Beverage Industry: Wiped film evaporators are used in the food and beverage industry to concentrate and separate various liquid products such as fruit juices, milk, coffee extracts, and other liquids. They are also used in the production of alcoholic beverages such as whiskey and rum.
- Pharmaceutical Industry: Wiped film evaporators are extensively used in the pharmaceutical industry for the concentration and purification of drug solutions, solvent recovery, and the removal of impurities. They are also used in the production of vitamins, amino acids, and other organic compounds.
- Chemical Industry: Wiped film evaporators are used in the chemical industry for the processing of high boiling point compounds such as resins, polymers, and other specialty chemicals. They are also used in the production of fragrances, flavors, and other aromatic compounds.
- Cannabis Industry: Wiped film evaporators are used in the cannabis industry for the extraction and purification of cannabinoids and terpenes from the plant material. They are also used in the production of cannabis concentrates such as distillates, isolates, and tinctures.
- Petrochemical Industry: Wiped film evaporators are used in the petrochemical industry for the processing of heavy oils, waxes, and other petroleum products. They are also used in the production of lubricants, greases, and other specialty petroleum products.
- Environmental Industry: Wiped film evaporators are used in the environmental industry for the treatment and purification of industrial wastewater and other contaminated liquids. They are also used in the recovery of valuable chemicals from waste streams.
Advantages of Wiped Film Evaporator:
Wiped film evaporators offer several advantages over traditional evaporators, including:
- High Efficiency: Wiped film evaporators offer high evaporation rates, making them ideal for processing large volumes of fluid.
- Heat-Sensitive Materials: Wiped film evaporators can process heat-sensitive materials without causing any thermal degradation.
- Minimal Fouling: Wiped film evaporators are designed to minimize fouling, reducing the need for cleaning and maintenance.
- Small Footprint: Wiped film evaporators have a small footprint, making them ideal for use in confined spaces.
Final Thoughts:
Thin film evaporators are an important tool for processing heat-sensitive materials in a variety of industries. They offer high efficiency, minimal fouling, and a small footprint, making them ideal for use in confined spaces. However, they are more expensive than traditional evaporators and require regular maintenance to ensure proper operation. If you are considering using a wiped film evaporator for your application, it is important to understand the design, operation, and limitations of this type of evaporator.