What is the difference between a Falling Film evaporator and a Rising Film evaporator?

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The evaporator is the device that is used to turn the liquid form of a substance into a gaseous state via heat transfer. The evaporator consists of various types such as Falling film evaporators, Rising film evaporators, forced circulation evaporators, and many more.

What is Falling Film Evaporator?

A falling film evaporator is a device that is used to separate substances with different boiling temperatures. Industries use this machine to evaporate temperature-sensitive substances and obtain concentrates under controlled conditions. These evaporators are being used in various fields such as pharmaceuticals, food, chemical, etc. 

The heat-sensitive liquid flows downward in a thin film along with the heating tube walls. Before entering the head of the evaporator, the liquid substance gets heated to boiling temperatures. After entering the head of the evaporator, the liquid flows down through the inside surface of the heating tubes. Then, steam is applied to the tubes' outer surface and the liquid evaporates without direct contact with the steam. 

The falling film evaporators are designed in such a way that the liquid flows evenly down the surface of the tube and needs proper wetting of the surface. The non-moistured surface can cause incrustations and dry patches and obstruct the process. 

Uses of Falling Film evaporator:-

  • Industries use this evaporator to recover solvents and produce high-quality cannabis extract oil
  • It also acts as a recovery solvent unit to recycle the high-quality solvent.

Advantages of Falling film evaporators-

  1. This method includes limited heat exposure to the extract and the possibility of continuous operation. 
  2. It handles a large volume of throughput and automatic ease of use.
  3. This method is suitable for heat-sensitive products.
  4.  The short product contact time of falling film evaporators minimizes the thermal degradation effects.
  5. Falling film evaporators consist of low tube wall temperature and heat flux that minimizes fouling. 
  6. The performance of the falling film evaporators provides high efficiency for multiple effect designs. 

What is a Rising Film Evaporator?

A rising film evaporator is a vertical shell and tube, heat exchanger. The evaporated liquid fed from the gets into the long tubes and gets heated with steam condensing outside the tube from the shell.  At top of the vapor-liquid separator, the mixture of liquid and vapor is separated. Due to the high velocity of vapor lift, we achieve good thermal performance. The upward movement directly affects and creates a high degree of turbulence in the liquid. This method is very useful for viscous products that tend to foul against heating surfaces. 

There is a wide range of rising film evaporator applications such as effluent treatment, production of polymers, food production, thermal desalination, pharmaceuticals, and solvent recovery. In industries, rising film evaporators are used as reboilers for distillation columns, flash evaporators, pre-heaters, etc. 

Advantages of Rising film evaporators-

  • The rising film evaporator possesses a low residence time of the liquid feed in the evaporator.
  • The low residence time of this evaporator allows the usage in high operating temperatures and assures high product quality.
  • This evaporator is high on heat transfer coefficient. It reduces the overall heat transfer area.

Features of Rising film evaporators-

  1. Rising film evaporators are used for feeds that contain small amounts of solid particles.
  2. With this evaporator, we can also use liquids of high viscosity and fouling components.
  3. This evaporator allows the evaporation of solvents
  4. A rising film evaporator consumes low fuel and is also used for effluent treatments.
  5. For moderate vacuum and heat-sensitive products rising film evaporators are the economical alternative.
  6. To reduce steam consumption, multiple-effect arrangements are made.


  • Based on the concentration of dilute solutions of plant extract in water 
  • Acts as a pre-concentration  before the final drying up to saturation point
  • Food and Dairy industries
  • Textile industries
  • Herbal industries

Falling film evaporators VS Rising film evaporators-

  • In the Falling evaporator, liquid enters at the top of the exchanger for boiling, on the other hand, the liquid enters at the bottom of the vertical vessel.
  • Internal distributors of the falling film ensure that tubes are equally wet.
  • In the rising film, the liquid gets heated and slightly boils while passing up through the first pass. 
  • The liquid forms along the inside of the tubes in the falling evaporators. 

Wrapping it up:-

Falling film evaporators and Rising film evaporators are used in different industries for various purposes. In the above article, we have discussed the differences between these two to make things more clear. 

If there is also a need for these types of evaporators, crystallizers, Heat exchangers, spray Dryers, or other industry-related equipment, ‘AlaquaInc’ is there. At ‘AlaquaInc you will get all industry-related equipment of the best quality and at market competitive prices. 

Contact them for more information.

Website:- www.alaquainc.com

Phone:- +551 482 7568

Mail:- [email protected]

Address:- Alaqua 7004 Boulevard East,

Suite 28A, Guttenberg, NJ USA 07093