Eighty years ago, in 1944, Dr. Hans Müller from Winterthur, Switzerland filed a patent application for a device designed to process liquid substances at the Swiss Federal Institute of Intellectual Property in Bern. Liquids prone to fouling on heated surfaces, as well as thermally sensitive or viscous substances, have always presented significant challenges in thermal processing.
Müller’s original patent describes the thin-film evaporator as follows:
“… A device for processing liquid substances, characterized by a vertical heated cylinder and an internal stirrer that distributes the liquid along the inner wall of the treatment zone, moving it along the heating surface with rigid blades mounted on a rotor.”
The patent for a vertical cylindrical thin-film evaporator with a rigid-blade rotor was granted in 1947. Recognizing its immense potential, Luwa AG, based in Zürich, acquired the patent. Subsequently, a pilot plant was established in Zürich, and the first machines were manufactured in Muri, Switzerland. To this day, this type of thin-film evaporator is globally recognized under the name LUWA evaporator.
In 1919, Richard Samesreuther founded Samesreuther & Co. GmbH in Butzbach, Hesse, Germany. Initially, the company specialized in repairing or manufacturing locomotive fireboxes using a patented copper-welding process. Later, it expanded into producing apparatus for high operating pressures from special materials for the chemical manufacturing industry. These included the company’s patented Samka ranges of full- and half-pipe heating coils and dimple jackets.
FIGURE 1. The original patent for thin-film evaporation technology was filed in Switzerland in 1944. The technology is now widely used in industrial separations, including distillation, concentration, stripping, deodorizing, degassing and more (Image courtesy of Buss-SMS-Canzler GmbH)
In 1952, Samesreuther & Co. GmbH signed a contract with Farbenfabriken Bayer AG to manufacture and distribute a vertical cylindrical thin-film evaporator with movable metallic wiper blades, known as the Sambay evaporator.
A third type of thin-film evaporator was introduced in 1957 by Carl Canzler KG in Düren, Germany. This design employed a rotor with movable graphite wiper blades and was used in both thin-film and short-path evaporators. Carl Canzler KG acquired a license for this design from Arthur Smith of Rochester, N.Y., and marketed it under the name Rotafilm with Smith Rotor.
In 1964, Samesreuther & Co. GmbH became Samesreuther Müller Schuss GmbH (SMS), leading to the formation of Luwa-SMS GmbH in 1972. Since then, LUWA evaporators have been produced alongside Sambay evaporators at the Butzbach facility. Following the acquisition by Buss AG in 1983, the company was renamed Buss-SMS GmbH Verfahrenstechnik, and the current name, Buss-SMS-Canzler GmbH, was adopted after the merger with Canzler GmbH in Düren in 2003.
Building on the foundation of these vertical, cylindrical thin-film evaporators, numerous additional machines for the thermal treatment of mixtures that are difficult to handle (due to heat sensitivity or extreme viscosity, for example) have been developed. All of these machines operate on the same basic principle: processing a continuously flowing thin film of product, influenced mechanically, with short residence time and indirect heat transfer. These include vertical and horizontal conical thin-film evaporators, short-path evaporators, thin-film evaporators for highly viscous materials, and vertical and horizontal thin-film dryers.
Thin-film evaporation technology has continued to advance over the past 80 years. Additionally, modern capabilities in process and mechanical engineering — including computational fluid dynamics (CFD), discrete-element and finite-element methods, and process simulation software — as well as more precise and efficient manufacturing techniques for various materials, enable the development of optimal, customized solutions for nearly any specific application.
Drawing on over 13,000 documented trials conducted at former laboratories and pilot plants in Zürich, Butzbach, Düren and the current facility in Pratteln, Buss-SMS-Canzler GmbH has designed and manufactured nearly 7,000 rotating thermal-separation machines. ■
Edited by Mary Page Bailey
Further reading
1. Evaporators: Design Concepts and Equipment Selection, Chem. Eng., January 2020, pp. 27–38.
2. Evaporators: Energy Conservation Strategies and Process Control, Chem. Eng., October 2020, pp. 41–43.
3. Heat Transfer in Wiped-Film Evaporators, Chem. Eng., November 2016, pp. 44–47.
4. Improve Efficiency with Better Evaporation and Drying Equipment, Chem. Eng., September 2015, pp. 26–31.