Some Concepts in Evaporation and Their Origins

Abstract

Practical experience showed the need for quantitative data on the fouling of evaporator surfaces. This data was accumulated by means of an alternating and direct current resistance thermometer device developed for the purpose and applied in pilot scale experiments. The most important concept in fouling is the temperature of the wetted surface. Of decreasing importance are wetting of the surface, thinness of the stagnant liquid layer on the surface, and consistency of the liquid boiling.
These concepts were used by the author to create two new designs now in plant use. These are the expanding tube and Wurling evaporators. A control system has been successfully simulated to embody the concepts. This automatic system may be applicable to every design of forced circulation evaporator.