What is a Falling Film Evaporator Used for?
A falling film evaporator is widely used in a great number of fields, such as the pharmaceutical, food, chemical, light fields and other fields for the evaporation and concentration of water and organic solvents. And falling film evaporators are especially suitable for the evaporation and concentration of thermal sensitive materials. It can operate continuously under the conditions of vacuum and low temperature, featuring the high evaporation efficiency, energy conservation and low operating cost. As well, materials can be ensured not to change easily during the evaporation.
How does a Falling Film Evaporator Work?
The working principle of falling film evaporators can be described as follows. The liquid is added to the upper tube of the heating chamber of the falling film evaporator. Through the liquid distribution and film forming device, it is evenly distributed into the heat exchange tubes. Under the action of gravity and vacuum induction and air flow, it forms a uniform film from the top to the bottom. During the flow, it is heated and vaporized by the shell-side heating medium. The generated steam and the liquid phase enter the separation chamber of the evaporator. The vapor-liquid is sufficiently separated, and the steam enters the condenser for condensation (single-effect operation) or enters the next-effect evaporator. The medium is heated to achieve multi-effect operation, and the liquid phase is discharged from the separation chamber.
Key Benefits of Falling Film Evaporator
Falling film evaporators are quite popular because they have so many benefits. The benefits of falling film evaporator are as follows:
- A falling film evaporator can be used for the extraction and separation of heat-sensitive substances.
- A falling film evaporator can provide high efficiency for multiple effect designs, which saves more time and energy of the whole system for users.
- There will be less fouling in a falling film evaporator, because a falling film evaporator has low tube wall temperature and heat flux.
- During the working process of a falling film evaporator, there will be short product contact time, which can minimize thermal degradation effects.
Problems and Solutions of Falling Film Evaporator
When users are using a falling film evaporator, there can be some problems happening sometimes. These problems are some warnings for us to adjust the falling film evaporator or replace some old accessories. These are some detailed problems and their solutions:
- The vacuum decreases during the evaporating process, which leads to the decrease of evaporation.
- The vacuum of the falling film evaporator equipment is too low during the closed evaporation.
- Various effect material separators are often put on the sight glass, and the condensed water is heavily charged.
- When the steam consumption increases significantly, the nozzle of the heat pump should be checked for blockage or damage as the solution.
- The solution aimed at this problem is to check the evaporator distribution plate. First of all, check if the distribution material hole got stuck, which leads the uneven distribution of material. Secondly, check if the heater tubes got stuck. Thirdly, check if the temperature difference between condenser inlet and outlet is too small.
- The solution aimed at this problem is to check if vacuum got destroyed and if all the joints leak the vacuum.
- The solution aimed at this problem is to check whether the circulation pumps are intact, and check whether there is air leakage in the pipeline in front of the pump, which causes cavitation of the pump.
- Under normal system evaporation, the amount of evaporation got reduced. The solution is to wash the car with 2% NaOH solution.