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降膜废水蒸发器优点缺点和一般蒸发器对比 当前位置: 网站首页 > 降膜废水蒸发器优点缺点和一般蒸发器对比
降膜废水蒸发器优点缺点和一般蒸发器对比
加入时间:2018-07-23 
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降膜蒸发器是一种高效蒸发设备,其与升膜蒸发器、刮板式薄膜蒸发器统称为薄膜蒸发器。薄膜蒸发器优点显著,在化工、轻工及食品加工行业内被广泛应用,以达到液体浓缩的目的。降膜蒸发器的结构其实并不复杂,可以简单理解为立式列管式换热器内加一套布膜装置,但是它与普通换热器又有一个明显的差异,其壳程固定为加热流体,管程固定为被蒸发物料。


The falling film evaporator is a kind of high efficiency evaporation equipment, which is called the film evaporator with the rising film evaporator and the scraper type thin film evaporator. Thin film evaporator has obvious advantages and is widely used in chemical industry, light industry and food processing industry to achieve the purpose of liquid concentration. The structure of falling film evaporator is not complicated, can be understood as a simple vertical tube for a cloth membrane device heater, heat exchanger and ordinary but it has an obvious difference, the shell is fixed to the heating fluid, Guan Cheng fixed evaporated material.


降膜蒸发器管程所走物料都是从管顶进入换热管,借助自身重力沿管内璧向下流,在进入换热管之前,需经过布膜器布膜,因而进入换热管的时候会呈薄膜状,在物料自上而下的过程中水分被蒸发出去,从而达到物料浓缩的目的,壳程如果是用蒸汽冷凝加热或导热油加热,若使用蒸汽则上进下出,若选用导热油则应自下而上。由此可见,管内外介质流向不一定都是逆流。


Falling film evaporator tube take materials are from the top of pipe in the heat exchanger tube, with its own gravity to the downstream along the tube wall in the heat exchanger tube before, after the cloth membrane cloth membrane, which enters the heat exchanger tube is thin, in the process of material from the top to the bottom water is evaporated sent out, so as to achieve the purpose of material concentration, the shell if it is heated by condensing steam heating or heat conducting oil, if the use of steam coming out under, if the selection of heat conducting oil should be bottom-up. Thus it can be seen that the flow direction of the medium and outside the tube is not always countercurrent.


但这并不重要,因为管内压力基本不变,不会引起流体温度变化,管内介质温度改变只是由于介质浓度变化而引起沸点升高(这也只是略微升高而已)。

But this is not important, because the pressure inside the tube is basically unchanged, which will not cause the change of the fluid temperature. The change of medium temperature in the tube is due to the increase of boiling point due to the change of medium concentration, which is only a slight increase.

降膜蒸发器优点分析:

(1)换热管内物料停留时间短,不会影响热敏性物料化学性质;

(2)换热管内物料呈薄膜状且流速快,蒸发换热系数大;

(3)压降几乎为0,管程物料处于常压环境,完全靠自身重力沿管内壁往下流,可节能;(4)由于管程物料靠自身重力沿管内壁往下流,而非用压差来推动,所以可选用低温差;

.(5)管程空间物料滞留量非常少;

(6)管程物料加热后表现为对流沸腾,所以换热管表面状态几乎不影响物料沸腾。降膜蒸发器缺点分析:

(1)设备蒸发效果与分布器有直接关系,对分布器的设计制造安装要求都非常高;

(2)设备安装要求高,主要表现为垂直度要求,假设换热管长度为9m,设备垂直度则要求≤6. 4mm;

(3)需保证设备换热管内壁完全湿润但布膜厚度又不能太大,需对物料进料量和换热管长度进行非常准确的设计计算才能满足这样的要求;

(4因设计制造要求都很高导致设备采购成本非常高;

(5)对于易结垢或含固体悬浮物的物料不适用。



Analysis of the advantages of the falling film evaporator:


(1) change of the material in the heat pipe with short residence time, does not affect the chemical properties of heat sensitive materials;


(2) the material in the heat exchange tube is thin film and the flow velocity is fast, and the heat transfer coefficient is large.


(3) the pressure drop is almost 0, and the pipe material is in the atmospheric pressure environment. It can flow down along the inner wall of the pipe entirely, and it can save energy. (4) because the pipe material flows downward along the inner wall of the pipe itself instead of the pressure difference, the low temperature difference can be chosen.


(5) there is very little retention of space materials in the tube range;


(6) the tube material is heated by convection boiling, so the surface state of the heat transfer tube almost does not affect the boiling of the material. Shortcoming analysis of falling film evaporator:


(1) the effect of the evaporation of the equipment is directly related to the distributor, and the requirements for the design, manufacture and installation of the distributor are very high.


(2) the equipment installation requirements, mainly for the requirement of verticality, assuming the tube length is 9m, is less than 6. 4mm vertical equipment;


(3) it is necessary to ensure that the inner wall of the heat exchanger tube is completely wet, but the thickness of the film can not be too large. It is necessary to design and calculate the material feed quantity and the length of the heat exchanger tube accurately.


(4 because of the high requirements of design and manufacture, the cost of equipment procurement is very high;


(5) it is not applicable to materials that are easily fouled or containing solid suspension.


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