The falling film evaporation is raw material liquid from the falling film evaporator heating room to join the top of the tube end of the liquid distributor and film device, uniform distribution to the heat exchanger tube, in the solution itself under the action of gravity and vacuum induction and airflow, the solution along the inner wall of the tube to form a uniform film flow from top to bottom. In the flow process, the shell process heating medium heating vaporization, the resulting steam and liquid phase together into the evaporator separation chamber, gas-liquid separation, steam into the condenser condensation (single-effect operation) or into the next effect of the evaporator as a heating medium, so as to achieve the multi-effect operation, the liquid phase is discharged from the separation chamber. In the top of the heating tube is equipped with liquid distributor, in order to make the liquid into a film, suitable for viscosity, not suitable for crystallization of the material liquid.
The falling film evaporator is used for evaporation and concentration of water or solvent solution in food, chemical, light industry and other industries, and can be used for waste liquid treatment in the above industries. Applicable to heat-sensitive materials, the equipment in the vacuum low-temperature conditions for continuous operation, with high evaporation capacity, energy saving, low operating costs, and can protect the material in the process of evaporation invariance.
The material liquid enters the material liquid distributor from the top. Material liquid distributor to material liquid evenly distributed to each heating tube, and make it is film-like along the inner wall of the tube downward flow, liquid film by the heat transfer from the wall and evaporation vaporization. When the heat transfer temperature difference is not large, the vaporization occurs in a strong perturbation of the inner surface of the membrane, rather than in the heating tube and the liquid film interface (i.e., the inner surface of the heating tube), so it is not easy to scale. The resulting vapor is usually flowing downward in parallel with the liquid film. Due to the vaporization surface is very large, the steam in the liquid foam entrainment amount is small, material liquid in the inner wall of the tube was membrane flow, not full of the entire cross-section of the tube, so the amount of material through the liquid can be very little.
The falling film evaporator because of its liquid film heat transfer, in the use of its heat transfer coefficient in general will be higher than other forms of evaporator, falling film evaporation no liquid column static pressure, heat transfer temperature difference is higher than other forms of evaporator, so can get good heat transfer, one-time investment is small, is the owner of the preferred form of evaporator.
Inside the effect body for the arrangement of the thin tube, tube for the product, outside the steam, in the product from top to bottom of the flow process due to the increase in the area of the tube and make the product was membrane flow, in order to increase the heat area, through the vacuum pump in the effect body to form a negative pressure, reduce the boiling point of the product in the water, so as to achieve the concentration of the product evaporation temperature of 60 ℃ or so.
