| Thin film evaporator | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
First. Overview The thin film evaporator is a new type of high-efficiency evaporator which is made into a film by a rotary wiper and has a high-speed flow, high heat transfer efficiency, short residence time (about 10 to 50 seconds), and can be used for falling film evaporation under vacuum conditions. It consists of one or more jacketed cylinders and a rotary wiper inside the cylinder. The wiper continuously feeds the feed onto the heated surface into a thick, uniform liquid film and moves downward; during this process, the low boiling component is evaporated and the residue is discharged from the bottom of the evaporator. Second, the performance characteristics ·Small vacuum pressure drop： The vaporized gas of the material is sent from the heating surface to the external condenser, and there is a certain pressure difference. In a typical evaporator, this pressure drop (Δp) is usually relatively high and sometimes even too high to accept. The scraper-type thin film evaporator has a large gas traversing space, and the pressure inside the evaporator can be regarded as almost equal to the pressure in the condenser. Therefore, the pressure drop is small and the vacuum degree can reach 5 mmHg. ·Low operating temperature： Due to the above characteristics, this allows the evaporation process to be maintained under higher vacuum conditions. Due to the increase in the degree of vacuum, the corresponding boiling point of the material is rapidly lowered, so that the operation can be carried out at a lower temperature, which reduces the thermal decomposition of the product. ·Short heating time： ;Due to the unique structure of the scraper-type thin film evaporator, the wiper has a pumping action, so that the residence time of the material in the evaporator is very short; in addition, the product does not stay in the evaporation due to the high-speed turbulence of the film on the heated evaporator. Surface. Therefore, it is especially suitable for evaporation of heat sensitive materials. ·High evaporation： The decrease of the boiling point of the material increases the temperature difference of the same heat medium; the function of the wiper reduces the thickness of the liquid film in a turbulent state and reduces the thermal resistance. At the same time, in this process, the material is inhibited from adhering to the heating surface, and the scale is accompanied by good heat exchange, thereby improving the overall heat transfer coefficient of the scraped film evaporator.  ·Large operational flexibility： It is precisely because of the unique properties of the scraped film evaporator that it is suitable for the treatment of heat sensitive and smooth evaporation, high viscosity and abrupt increase in viscosity with concentration, the evaporation process can also be smoothly evaporated. It can also be successfully applied to the evaporation and distillation of materials containing solid particles, crystallization, polymerization, scaling and the like. Third, the application area In the heat exchange project, the scraper type thin film evaporator has been widely used. Especially for the heat exchange of heat sensitive materials (timely), the wiper facilitates the heat exchange and can be used for the distillation of complex products through different wiper designs. The wiped film evaporator has been used in the following fields for evaporation concentration, desolvation, stripping, reaction, degassing, deodorization (gas) taste, etc., and has achieved good results: Chinese and Western medicine: antibiotics, sugar liquid, Leigong Teng, Astragalus and other Chinese herbal medicines, methyl imidazole, mononitramine and other intermediates; Light industry food: juice, gravy, pigment, flavor, spices, enzyme preparation, lactic acid, xylose, starch sugar, potassium sorbate; Oil and fat daily: lecithin, VE, cod liver oil, oleic acid, glycerin, fatty acid, waste lubricating oil, alkyl polyglycoside, alcohol ether sulfate, etc.; Synthetic resin: polyamide resin, epoxy resin, paraformaldehyde, PPS (polyacrylic acid acrylate), PBT, propylene formate; Synthetic fibers: PTA, DMT, carbon fiber, polytetrahydrofuran, polyether polyol, etc.; Petrochemistry: TDI, MDI, trimethylhydroquinone, trimethylolpropane, sodium hydroxide, etc.; Pesticide organisms: acetochlor, pretilachlor, chlorpyrifos, furanol, chlorhexidine, herbicides, insecticides, herbicides, herbicides; Waste water: inorganic salt wastewater, etc.; Fourth, the working principle The material enters the evaporator radially from above the heating zone; the distributor distributes to the evaporator to heat the wall surface, and then the rotating wiper scrapes the material onto the continuous uniform heating surface to form a thick and uniform liquid film, and spirally Push forward. In this process, the rotating wiper ensures high-speed turbulence of the continuous and uniform liquid film, and prevents the liquid film from coking and fouling on the heating surface, thereby increasing the total coefficient. The light component is vaporized to form a vapor stream which rises through the vapor-liquid separator to an external condenser directly connected to the evaporator; the reconstituted portion is discharged from the cone at the bottom of the evaporator. The material enters the evaporator radially from above the heating zone; the distributor distributes to the evaporator to heat the wall surface, and then the rotating wiper scrapes the material onto the continuous uniform heating surface to form a thick and uniform liquid film, and spirally Push forward. In this process, the rotating wiper ensures high-speed turbulence of the continuous and uniform liquid film, and prevents the liquid film from coking and fouling on the heating surface, thereby increasing the total coefficient. The light component is vaporized to form a vapor stream which rises through the vapor-liquid separator to an external condenser directly connected to the evaporator; the reconstituted portion is discharged from the cone at the bottom of the evaporator. At the top of the wiped film evaporator is equipped a centrifugal separator designed according to the material characteristics to separate the droplets in the rising steam stream and return to the distributor. Five, model, specifications
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
