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Selection of evaporators in MVR devices
heure de libération：2019-06-10 11:14:00
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In the mechanical vapor recompression (MVR) plate evaporator, selecting the evaporator is essential to ensure efficient and stable operation of the system.
There are three types of plate evaporators:
1. A rising film type plate evaporator represented by APV A435 type;
2. A rising film evaporator represented by GEA CT193 and ALFA EC500;
3. Falling film evaporator represented by AMV company A458
Their features are as follows:
|
project |
APV rising film |
GEA、ALFA rising film |
APV Falling film |
|
Structure characteristics |
Four "twin" plates are used to form a rising and falling film transfer unit, and then the units are assembled in a frame, and the plates are sealed and guided by elastic gaskets. Detachable structure |
The two "twin" plates are welded together to form a heat transfer unit, and then the transfer units are assembled in a frame, and the transfer units are sealed and guided by elastic gaskets. Semi-welded structure |
The two "twin" plates are arranged in phase, assembled in a frame, and sealed and guided by elastic gaskets between the plates. Detachable structure |
|
Relative flow of steam and materials |
Cross flow |
Counter current |
Cross flow |
|
Material entry status |
The throttle plate is used to control the material to enter the board evenly, and the material has a jetting and flashing effect through the throttle plate. When the material is heated by steam, steam is generated to drive the unvaporized material to rise, forming a liquid film. |
The material submerges the lower end between the plates, and is heated by steam to generate steam, which drives the un vaporized material to rise to form a liquid film. |
The throttle plate is used to control the material to evenly enter the upper part of the plate, and the material has a jetting and flashing effect through the throttle plate. When the material is heated by steam, steam is generated to drive the un vaporized material to move downward to form a liquid film. |
|
Aspect ratio of heat transfer area |
The vapor-liquid mixture on the rising film plate passes over the steam plate at the top of the plate and enters the falling plate. The falling plate can be regarded as the extension of the rising film plate, so the aspect ratio is twice as large as that of the single plate, and the heat transfer dead angle is doubled. Very small. |
The aspect ratio is 1.2~1.4, and the heat transfer dead angle is large during low load operation. |
A variety of aspect ratios, forming a variety of specifications, small heat transfer angle. |
|
Wetting requirements for interplate type |
no request |
78-100 l/(cm².h) |
0.7-1.0 l/(cm.h) |
|
Manufacturing, cleaning, maintenance |
The manufacturing is more troublesome, and the structure has been improved recently, and the manufacturing is much simpler. Easy to clean and maintain. |
Welding is time consuming, and the welding is inconvenient to clean. In this channel, if there is debris, it is easy to scale and induce corrosion. |
Simple to manufacture, easy to clean and maintain. |
|
application situation |
First introduced. Nowadays, there are many specifications in China and they are widely used. |
Welding channel, can withstand high pressure, good sealing performance, can withstand higher temperature, can be used for evaporation of toxic and flammable medium. |
There is no such product in China. There is a similar product, the steam material is cocurrent. |
The evaporators of APV, GEA, and ALFA are almost all developed at the same time. APV has many products and models, and has its own design for various working conditions. Therefore, its application fields and applications are higher than GEA or ALFA. Because of the special nature of MVR evaporation, (the material is generally concentrated from about 20% to 30% to about 50% to 55%, and the evaporation temperature is about 70-85 °C. The ratio of feed to evaporation is about 1.5-2. The requirements for the wetting amount of the rising film or falling film evaporator cannot be met. In order to meet this requirement, it is necessary to recirculate. Reflowing may cause discoloration, odor, and increased power consumption. Therefore, the evaporation of the MVR using the APV lifting membrane structure is better, which has been confirmed in the operation practice.
GEA and ALFA rising film evaporators are semi-welded type. The welding channel has high pressure bearing capacity and good sealing performance, so it can be applied to the evaporation and concentration of toxic and flammable substances.
In addition to considering the above-mentioned type factors, the choice of the evaporator should also consider the matching of the processing amount and the specification, so as to avoid the uncoordinated phenomenon of the big horse-drawn car or the big horse.
Nanjing Gaojie advantage:
In order to meet the needs of MVR plate evaporators for different processes and different market demands, our company's existing plate evaporators have three series of rising film, lifting film and falling film.
There are: riser veneer area: 1.32 and 1.5 and 2.0m2
rising film veneer area: 0.4, 0.65, 0.85, 1.5m2
Membrane board area: 0.25, 1.5m2
Nanjing Gaojie: Provides on-demand evaporative application solutions in all directions, and warmly welcome new and old customers to call us!