principle 

The forced circulation evaporator actually evolved on the basis of the external circulation evaporator. External circulation evaporator (or natural circulation evaporation or central circulation tube evaporator) refers to the natural circulation movement of the material liquid due to the effect of evaporation during the evaporation process, and the density difference between the material and liquid in the heat exchanger and the circulation tube. It belongs to the natural circulation type evaporator. The common shortcoming of external circulation and central circulation tube evaporator is that the circulation speed of the material liquid is relatively low. When the material liquid with high viscosity, easy to scale or crystallize is processed, the heat transfer effect is not good, and it is easy to scale. As shown in the figure below, if a circulation pump is installed between the material-liquid circulation pipe and the heat exchanger to increase the circulation speed, it is a forced circulation evaporator. The forced circulation evaporator uses external power to circulate, and the circulation pump is used to force the liquid to pass through the heating tube at a speed of 2-5m/s in one direction. The material liquid in the heating tube is heated to a superheated state without evaporating at a pressure higher than the normal liquid boiling point. After entering the separator, the pressure drops rapidly, causing part of the material liquid to flash or boil, and the material liquid is cooled to the boiling point under the corresponding pressure. Temperature, flash steam is discharged from the upper part of the separator, the material liquid is prevented from falling, and is sucked in by the circulating pump at the conical bottom, and then enters the heating tube to heat, and continues to circulate until it is concentrated to the designed concentration and discharged.

System Composition 

       Forced circulation evaporator, separator (crystallizer), condenser, forced circulation pump, feed regulating valve, vacuum and drainage system, sub-cylinder, operating platform, electrical instrument control cabinet and valves, pipeline and other systems.

Main Features

 ●Forced circulation evaporator through forced circulation, the material and liquid are heated evenly in the tube, which can prevent the "dry wall" phenomenon.

 ●The evaporation rate is high, the concentration ratio is large, and the forced circulation makes the material with higher viscosity easy to evaporate and concentrate.

 ●The circulating liquid flow rate in the heating tube is very high, which can prevent the product from boiling on the heating surface to form fouling or crystallization.

 ● Because the circulating liquid is maintained continuously, and the speed of circulation fluid in the pipe temperature can be controlled to suit the requirements of different products without the effects of temperature setting.

 ● Heating pipe may be a vertical one-way, two-way vertical, horizontal way, horizontal two-way, both the total height of the device is small but easy to clean and easy to wear tube wall.

 ●In concentrated crystallization, crystals can be separated from the circulating crystal liquid by adjusting the circulating flow rate and adopting a special separator design.

 ●The forced circulation evaporator has a large power consumption, relatively high power consumption, and high heating temperature of raw steam (primary steam). The heating area of this evaporator should not be too large.

Scope of Application

       The forced circulation evaporator is a large-scale low-energy-consumption and energy-saving concentrated crystallization equipment developed by our company. It has fast material liquid flow rate, high evaporation rate, large heat transfer coefficient, anti-salt precipitation, anti-scaling, non-scaling, and is widely used for scaling Material with properties, crystallinity, heat sensitivity (low temperature), high concentration, high viscosity and containing insoluble solids. Forced circulation evaporators can be divided into single-effect, double-effect and multi-effect evaporators. The heat transfer element can be selected from two heat exchange structures of tube type and plate type. The forced circulation evaporator is suitable for zero discharge of various miscellaneous salt wastewater, evaporation of high COD wastewater, evaporation and crystallization of inorganic salts, evaporation of materials with higher hardness, evaporation and concentration of landfill leachate.

       The forced circulation evaporator designed by Jiangsu Heide has the characteristics of small footprint, high heat transfer coefficient, high evaporation intensity, low energy consumption and energy saving. It is equipped with a self-developed control system and CIP cleaning system, making daily maintenance more convenient.