A falling film evaporator is a type of heat exchanger that uses a shell and tube design to evaporate heat-sensitive liquids. The evaporator pumps the feed into it from the top and uniformly disperses it throughout the heating tubes of the device. While partially evaporated, the liquid flows through tubes, forming a thin layer on the tube walls. The heating medium (usually steam) delivers the heat to ensure a high heat exchanger coefficient. Under the influence of gravity, the liquid and vapour move downhill. The vapour flow in the co-current direction aids the liquid’s downward descent. At the bottom of the falling film evaporators unit, the concentrated product and its vapour are separated from one another.

The design of Alaqua’s falling film evaporators takes into account two important considerations:

• To reduce the feed’s residence time, maximise heat transmission in the shortest period possible.
• The homogeneous distribution of heat ensures that no clumps or fouling occur on the inner side of the walls during the feed transfer.

A standard technique used during material selection ensures high and efficient heat transmission by considering the feed qualities. The distributor head prevents tube crusting by ensuring uniform wetting, addressing major maintenance issues in falling film evaporators.

How Falling Film Evaporator Works?

A falling film evaporator (FFE) is a form of vertically oriented shell and tube (S&T) heat exchanger used to separate two or more liquids with different boiling points.

Two compartments are housed in a shell and tube heat exchanger. Its most fundamental function is to put a heating or cooling fluid, referred to as the media, into indirect but close contact with a product fluid, referred to as the process fluid. The shell and tube heat exchanger exchanges energy as heat between the media and the process fluids. In an S&T heat exchanger, the hotter media transfers energy to evaporate a process fluid component.

In the case of falling film evaporators, the heating medium cycles through the shell side of the S&T heat exchanger. The evaporator receives the process fluid on its tube side. While, the heating medium vaporizes a portion of the product, transferring energy into the product.

Uniformly pour process liquid into falling film evaporators, distributing it through heating tubes in the heat exchanger. Ensure the equal dispersion of the liquid to allow it to flow down the inside walls of each tube. So, the term “falling film” describes the liquid film descending down tubes, giving the heat exchanger its name.

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Why Falling Film Evaporators?

A falling film evaporator proves highly efficient and effective as a heat exchanger. Numerous firms in various key sectors have been progressively transitioning from outdated rising film evaporators, calandria-type evaporators, or forced circulation style evaporators to falling film evaporators due to the exceptional thermal performance achieved by well-designed FFEs.

The development and maintenance of a very thin film of rapidly descending liquid laminated to the internal surface of the evaporation tubes allow falling film evaporators to attain their excellent thermal performance. An equally dispersed liquid layer maximizes the contact between the process liquid and the heating medium, facilitating the fastest energy transfer from the media to the process fluid. This entails quicker evaporation rates and the capacity to employ a cooler heating medium, both of which are advantageous for treating thermally degraded materials.

To achieve this high level of performance, evenly disperse the descending liquid throughout all the tubes, equally disseminate it around the circumference of each tube, thoroughly laminate it to the inside surface of each tube, and ensure it travels down each tube at the optimal velocity. So, tubes that haven’t been adequately wetted can cause thermally labile products to degrade, are the leading source of fouling evaporators services, and have poor thermal performance.

Falling Film Evaporator Applications:

• Pharmaceuticals
• Food and Beverages
• Dairy Industry
• Papers
• Chemical Industry
• For products with low fouling property

Alaqua optimizes its flow lamination technology for each FFE it designs and builds. So, when designing the flow lamination system, Alaqua acknowledges that various applications may have a unique mix of variables, such as solids content, extract content, desired (percent) reduction in the solvent, and vapour velocity, which must be taken into account. So, the result is a small FFE with high throughput, little fouling, and consistent, regulated evaporation temperatures.

Various interpretations of falling film evaporators are quickly gaining favour, particularly in the hemp business. While, the performance and dependability of an FFE are highly dependent on the designer’s real technical skills. Alaqua takes pleasure in offering high-performance equipment and equipment services that have been meticulously developed, produced, and field tested. Contact us today to know more about our processing equipment and its services!