|
A climbing/falling film plate evaporator is a specialized type of evaporator in which a thin film of liquid is passed over a rising and falling plate to allow the evaporation process to occur. It is an extension of the falling film evaporator, and has application in any field where the liquid to be evaporated cannot withstand extended exposure to high temperatures, such as the concentration of fruit juices. ==Design== The basic design of the climbing/falling film plate evaporator consists of two phases. In the climbing phase, the liquid feed is heated by a flow of steam as it rises through a corrugated plate. In the subsequent falling phase, the liquid flows downward at high velocity under gravitational force. Evaporation and cooling occurs rapidly in the falling phase. There are several design variations that are commonly used in industrial field. These include single-effect and multiple-effect evaporators. The choice of evaporator design is dictated by constraints of the process. Fundamentally, there are four factors involved in designing this evaporator: * prevention of nucleate boiling; * short residence time; * waste stream production; and * post treatment. The main advantage of climbing/falling film plate evaporator is its short residence time. Since the liquid feed does not remain in the evaporator for long, this evaporator is suitable for heat/temperature sensitive material. Thus, this evaporator is used widely in food, beverages and pharmaceutical industries. Besides that, the colour, texture, nutritional content and taste of the liquid feed can be preserved too. Despite its functionality, this evaporator has a few drawbacks such as large energy consumption. Future development compromises installing large number of steam effects and recycle the steam where possible for better energy efficiency. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Climbing and Falling Film Plate Evaporator」の詳細全文を読む スポンサード リンク
|