Evaporation Methods as Applied to the Food Industry

Abstract

This chapter discusses the different types of evaporation methods as applied to the food industry. It briefly describes some of the early methods of evaporation such as the solar pond, shijoka, the open kettle, vacuum cooking, the jacketed kettle, and the vacuum evaporator. The steady advance in the development of metals and fabrication technique has had a profound effect on improvements in evaporating equipment and its uses. The development of stainless steel opened the way for tremendous improvement not only in evaporator construction but in sanitation methods. The chapter discusses in detail the working and design of the evaporation equipments such as tubular evaporators, forced-circulation evaporators, falling-film evaporators, indirect heat-pump evaporators, centrifugal thin-film evaporators, the vacreator, plate-type evaporators, heat-pump evaporators, control equipment, sonic and ultrasonic cleaning, and the carver-greenfield process. A recent development in evaporator design employs an entirely new approach to the vapor-condensing problem. Instead of attempting to compress the high-volume water vapor for reuse, a transfer of heat is made from the water vapor to another vapor that has the characteristic of low specific volume, and then this low-volume vapor is compressed. The use of water is at a minimum, and the heat thus absorbed can be salvaged again in the heating section of the evaporator. This type of low-temperature equipment has been discussed in detail. The development of the falling-film evaporator has undoubtedly been the greatest single step forward in evaporator design and construction since the introduction of vacuum cooking.