introduction
The forced circulation evaporator uses external power to circulate. A pump is used to force the solution to pass through the heating tube at a speed of 2-5m/s in one direction. Other evaporators are all natural circulation evaporators because of the density difference between the solution in the heating chamber and the circulation pipe. Their common shortcomings are that the circulation speed of the solution is low and the heat transfer effect is poor. A forced circulation evaporator can be used when handling solutions with high viscosity, easy fouling or easy crystallization
principle
The circulation of the solution in the equipment mainly depends on the forced flow generated by the external power. The circulation speed is generally up to 1.5-3.5 m/s. The heat transfer efficiency and production capacity are relatively large. The raw material liquid is pumped in from bottom to top by the circulating pump, and flows upward along the tube of the heating chamber. The mixture of steam and liquid foam enters the evaporation chamber and separates. The steam is discharged from the upper part, and the fluid is blocked from falling, and is sucked by the circulating pump through the conical bottom, and then enters the heating pipe to continue the circulation.
Features
Advantages: large heat transfer coefficient, anti-salt precipitation, anti-scaling, strong adaptability, easy to clean.
Disadvantages: large consumption of kinetic energy, long solution residence time; slightly higher cost and maintenance cost.
Scope of application
Forced circulation evaporator, suitable for evaporation and concentration in industries with scaling, crystallinity, heat sensitivity (low temperature), high concentration, high viscosity and containing insoluble solids, such as chemical, food, pharmaceutical, environmental protection engineering, waste liquid evaporation and recovery .
Troubleshooting
corrosion
The circulating evaporator tube sheet is affected by the medium and welding stress, and is prone to leakage and corrosion, which causes the decline of equipment functions and seriously affects the normal production of the enterprise. If it is not handled in time, not only will the equipment be scrapped, but it will even cause a major production accident. Using Mega-Ake EE-121K polymer composite anticorrosive protective coating for repair and protection, the product has superior adhesion, corrosion resistance and superior temperature resistance, which can solve such problems and extend the use of equipment Life, to ensure the safe and continuous production of the enterprise.
Scaling
The circulating cooling water of the circulating evaporator contains a large amount of salt substances, corrosion products and various microorganisms. Since it has not been treated with water, a large amount of calcium magnesium carbonate scale and algae will form on the water side after the evaporator runs for a period of time. Microbial sludge, slime, etc., these dirts are firmly attached to the inner surface of the copper pipe, causing deterioration of heat transfer, increased circulation pressure, and reduced vacuum of the unit, affecting the operating efficiency of the unit and causing greater economic losses.
Traditional cleaning methods usually use chemical cleaning-acid cleaning, which is effective for various depositions and saves time than mechanical methods. However, chemical cleaning is corrosive to the system and other metal parts, prone to corrosion of equipment pipelines, and pollutes the environment during discharge.
Fosttec is the world's first fully synthetic high-tech liquid descaling agent specifically designed to remove all scale, lime, mud, rust stains and other dirt deposits formed in water treatment equipment systems. The original solution and dilution solution can be directly used on all conventional equipment, including aluminum and some coated equipment. Because the main components are advanced biological agents, they are biodegradable, non-toxic, non-corrosive, and non-flammable, and can be directly discharged
Features of forced circulation evaporation system:
1)The circulation of the solution in the equipment mainly relies on the forced flow generated by the external power. The circulation speed can generally reach 1.0-3.5 m/s, and the heat transfer efficiency and production capacity are relatively large.maintenance
The lubricating oil of the generator reducer is 40# engine oil, and the refueling amount should be within the indicated height. Too much oil will cause stirring and heat generation, and too little oil will damage the oil film of the eccentric shaft pump and cause heat to increase the temperature.
1）Replace the secondary lubricating oil within 1 month at the beginning of use, and replace the lubricating oil once within 3-4 months.
2）After opening the lower head, unscrew the bolts at the bottom of the U-shaped groove of the rotor, and check the scrapers every four months to replace them.
3）Open the bottom bearing every two months, check the wear of the bottom bearing, and replace the bottom bearing if necessary.
4）According to the nature of the material, the inner cylinder should be soaked and cleaned regularly with warm water or solvent.
5）Add sealing liquid to the mechanical seal cavity once a month, the sealing liquid is 20# mechanical oil
Features are:
①Evaporated water volume can reach 0.5t/h~100t/h
②During normal operation, the system only uses electricity, the energy consumption per ton of water evaporated is 15KW.h to 100KW.h, and its operating cost is 1/8~1/2 of the multi-effect evaporation.
③It is the most energy-saving evaporator at present, mostly single-effect evaporation, small heating temperature difference, short residence time, suitable for heat-sensitive materials.
④The structure is compact and the floor space is small.
⑤The equipment realizes automatic operation through PLC control, and can operate continuously and stably for a long time.
The conical thin-film evaporator relies on a centrifugal force applied by the rotor to the material. This centrifugal force has two effective forces, one perpendicular to the heating surface and the other towards the direction of the large diameter end body (note: the same result also appears in the vertical cone type In the thin-film evaporator, the materials are accelerated by these forces, and the incoming materials ensure that the heating surface is fully moist, and does not depend on the evaporation ratio or the feed rate. Therefore, local material overheating and thermal degradation are reduced or completely eliminated.
In this process, the light components (low boilers) co-currently (in the same direction as the liquid film) enter the vapor-liquid separator through the horizontal thin-film evaporator, where the liquid droplets and foam produced by the vapor-liquid separation are It is crushed into the liquid phase (high boiler), and the separated vapor enters the external condenser or the next process; the recombined component (high boiler) climbs along the heating wall to the small end outlet and is discharged.
