外流自由降膜板式蒸發(fā)器是八十年代的蒸發(fā)器之一。其加熱元件采用兩張進口不銹鋼薄板，四周采用縫焊，經(jīng)鼓壓，點焊而成。板式蒸發(fā)器與其他蒸發(fā)器相比，在生產(chǎn)使用上不斷地顯示出其*性，目前，正在逐步地替代列管式蒸發(fā)器，可廣泛應用于多種行業(yè)。如淀粉及淀粉深加工漿液的濃縮，造紙制漿廢液的回收，酒精廢液的濃縮，鋁廠氧化鋁溶液的濃縮及其它工業(yè)污水的濃縮和回收等。

同列管式蒸發(fā)器相比，外流自由降膜板式蒸發(fā)器具有不易結垢，熱效率高，蒸發(fā)強度高，出液濃度高，操作平穩(wěn)，清洗方便等優(yōu)點。

Outflow free falling film plate evaporator is one of advanced evaporator in 1980s. its heating elements use two sheet stainless steel plate after pressure and welding to be one. Compared with other evaporator, it has more advantage and gradually replace the pipe type evaporators. It is used widely in various industries, such as thickening of starch or pulp of starch deep pressing, recovery of waste liquor of paper-making and pulping, thickening of alcohol waste liquid, alumina solution thickening and thickening and recovery of waster liquor of other industry. 

借助于循環(huán)泵，液體至加熱元件上面特別設計的液體分配器，通過分配器，液體均勻地淌在加熱元件上向下流動，并形成覆蓋整個加熱表面的均勻的液膜，液膜在從加熱元件上部起很短的距離內就加速到不穩(wěn)定速度。由于加熱元件表面凹凸不平，液體膜既在垂直方向又在水平方向流動，這種運動保證了加熱表面所有時間都是濕的，它同時還引發(fā)了再次混合，這樣，液體在其向下通過加熱表面時，水蒸氣就自然地從加熱元件之間溢出。由于極大的面積，水蒸氣速度很慢，這樣就不會干擾液體的流動。這就從根本上消除了分布不均和過濃縮的隱患，而分布不均和過濃縮會造成結垢。

外流自由降膜板式蒸發(fā)器與管式蒸發(fā)器相比具有許多優(yōu)點，如果我們檢查結疤的傾向，我們發(fā)現(xiàn)這種板式蒸發(fā)器本質上就是自清洗。在蒸發(fā)過程中形成的結垢，由于蒸發(fā)器中壓力變化及液膜的沖刷，能自由剝落。另外，由于液體循環(huán)速度慢，

消耗的能量就小。

With the aid of circulating pump, the liquid reach a special liquid distributor on heating element, the liquid flow evenly on the distributor and fall down, and form even liquid membrane cover on the whole heating surface. As the heating element surface is uneven, the liquid membrane can move both in vertical direction and horizontal direction, this type movement ensure the heating surface keeping wet all the time, and it also cause secondary mixing. Thus, when the liquid flow through the heating surface, the vapor can naturally overflow from the heating element. Because of great area the vapor flow slowly so that can not interfere with the flow of liquid. That is fundamentally eliminate the scaling caused by uneven distribution and enrichment thickening.

Compared with pipe type evaporators the outflow free falling membrane evaporator has many advantages. It is essentially self-cleaning. The scaling produced in the evaporation process can fall down freely under the pressure difference and the flushing of liquid membrane. In addition, due to slow liquid circulation speed, the energy consumption is small.