Abstract: The material to be evaporated is continuously fed into a stationary vertical cylinder where it is heated to a boiling condition through the cylinder wall while scraping material from said wall and while rotating the material about a vertical axis to maintain an upwardly opening cavity therein. Vapors drawn from the cavity to concentrate the material are passed through a first path; and concentrated material is displaced through a second path along part of the cylindrical surface while in a cooled condition to arrest the boiling and while maintaining the two paths separated. The discharge pressure of the concentrated material is increased by imposing a substantial resistance to its rotation in the second path; and to permit control of the evaporation, a sensing device is inserted in the second path to indicate changes in the temperature of the discharging concentrated material, which is substantially free of vapor.

Abstract: A product is continuously processed by passing it upwardly through a vertical heat exchange cylinder while continuously scraping the inner surface of the cylinder free of any product which may adhere thereto. This cylinder is surrounded by upper and lower outer cylinders to form upper and lower annular spaces through which respective heat exchange media are circulated, whereby the product can first be heated and then promptly cooled while passing through the heat exchange cylinder. To allow for different rates of expansion and contraction of the cylinders, a double expansion joint is provided between the two outer cylinders; and a temperature sensing device protrudes through this joint and into the heat exchange cylinder to measure the temperature of the product as it passes from the heating section to the cooling section of the heat exchange cylinder.