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    Home > Active Ingredient News > Drugs Articles > Routine maintenance of laboratory spray dryers

    Routine maintenance of laboratory spray dryers

    • Last Update: 2020-11-12
    • Source: Internet
    • Author: User
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    The daily maintenance spray drying of laboratory spray dryers is a method of systematic technology applied to material drying.
    the material is atomized in the drying chamber, and in contact with hot air, the moisture vaporizes rapidly, i.e. the drying product is obtained.
    method can directly dry the solution, emulsion into powdered or granular products, can save evaporation, crushing and other processes.
    spray granulation dryer is an important equipment in PTC thermal ceramic production process, which is more expensive, complex in composition and difficult to use and maintain.
    operation of the equipment can not only ensure the normal production of PTC thermal ceramics, but also appropriately extend the service life of the equipment, reduce production costs, so the correct operation of the equipment and strengthen maintenance is necessary.
    1 Spray granulation dryer principle and composition Granulation is an important process in the production process of PTC thermal ceramic sheet, the quality of ingestion directly affects the appearance, mechanical properties and temperature resistance characteristics of PTC ceramic sheet.
    granulation refers to the addition of a quantity of adhesive in the finely ground powder, evenly reconciling it to form a granular powder, which has better fluidity and lactation, so that in the press process can be obtained with a better strength, not easy to layer cracking tablets.
    In industrial production, spray drying is used to granulate, the basic principle is to spray powder with adhesive, sprayed with a sprayer into the granulation tower for atomization, the fog droplets in the tower by the hot air flow in the tower dried into granular powder, and then removed from the bottom of the drying tower.
    the pressure spray granulation dryer used by the company is mainly composed of feeding system, drying system, dust removal system, heating system and electrical system, and each system includes some related equipment.
    supply system consists of mixing drums, filters, diaphragm pumps and spray guns.
    ball-grinded secondary slurry is transferred from the ball mill to the mixing drum, pumped and transmitted through the filter by the diaphragm, and then through the spray gun into the drying tower.
    the spray slurry from the gun nozzle into the drying tower began the spray granulation drying process, the process is divided into three stages: (1) slurry atomization.
    the slurry is pressed into the drying tower by the diaphragm pump in the feeding system under pressure from the nozzle, the energy of the pressure is converted into momentum energy, the slurry is sprayed from the nozzle from the bottom up, forming a high-speed liquid film, the liquid film then split into droplets.
    size of the droplets produced by atomization is inversely inversely related to the pressure, and the production capacity of the nozzle is directly in directly in line with the square of the pressure.
    (2) fog particles dry into balls.
    The mist particles and the hot air work in a mixture of flow, the hot air enters the tower through the hot air dispenser on the top cover, the hot air dispenser produces a downward flow of air, and the fog droplets are sprayed from the bottom up into the hot air flow.
    droplets form spherical shapes due to surface stress, and because fog droplets have a large surface area, wherein moisture evaporates quickly and drys, and eventually shrinks to form dry spherical particle powder.
    (3) particle powder is removed.
    the spherical particle powder formed by the grain gradually subsides in the drying tower, separating it from the hot air, and the funnel cavity at the lower part of the tower allows the particles to gather and unload from the discharge port.
    finer particles, together with dry air, are extracted from a blower connected to the upper part of the funnel shape and enter the dust removal system.
    blowers, drying towers and pumping units that deliver hot air to drying towers have become drying systems.
    dust removal system consists of high-efficiency cyclone separators, cloth bag dust removers, centrifuges, etc.
    a fan feeds finer particles with dry air into an efficient cyclone separator.
    After effective separation, finer particles into the bottom of the separator collection tank recovery, the remaining exhaust gas containing a very small amount of fine particulate material by centrifugal fan inhalation cloth bag dust remover after dust collection again, to achieve the harmless treatment of exhaust gas, after the exhaust gas discharged from the chimney.
    addition, heating systems consisting of electric heaters and gas-fired air furnaces provide hot air for drying towers.
    electrical control cabinet and field sensors installed in the air in and out of the air port to monitor the temperature of the electrical system to monitor and control the entire spray granulation dryer in all major links to ensure the normal operation of the entire equipment.
    2 Daily operations and precautions In the daily production process, the necessary preparations should be made before starting the equipment.
    check that the bearings and sealing parts of each unit are loose, that the lubricant condition of each mechanical component, and that the water, wind, slurry valve port, etc. are in the desired position.
    then turn on the power supply to check whether the voltage and instrument is normal, and then check the amount and concentration of the slurry mixing barrel, etc. , if the problem should be eliminated in time.
    then turns on the fan and the fan in turn, and then turns on the heating switch to start heating up.
    start the feed pump and dust removal system when the out port temperature reaches the set temperature (usually around 130 degrees C).
    the pump reaches 2MPa, turn on the spray gun and start granulation.
    the operation of the equipment, the atomization situation and the working condition of the feed pump should be observed in a timely manner, and if there is a gun blocking phenomenon, the nozzle should be cleaned or replaced immediately.
    normal operation of the equipment, should also regularly collect materials, regularly check the operation of each system, record the process parameters, and pay attention to clean the vibration filter.
    end of grain granulation, the heating device should be turned off and the gas engine should be stopped.
    then close the gun valve, replace the spray gun, unscrew the nozzle and rinse it clean.
    the operation of the fan feeder and the pump can be stopped when the infringing temperature is reduced to less than 100 degrees C.
    cleaning the drying tower and dust remover, turn off the duster and air hammer, and then turn off the total power supply, complete the production operation.
    in case of emergency, immediately shut down the equipment, should shut down the fan and feed pump.
    in the event of a sudden power failure, pull out the gas engine, so that the tower naturally cool down, and then open the sewage valve, drain the slurry in the slurry pipe, and clean the equipment.
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