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Usage of Spray Dryer Time:2018.03.16
   The spray dryer is a type of continuous atmospheric dryer. The liquid material is sprayed with a special device into a mist, and it is brought into contact with hot air and dried. It is used for drying some heat-sensitive liquids, suspensions and viscous liquids, such as milk, eggs, tannins, and medicines, etc. It is also used in dry fuels, intermediates, soap powder and inorganic salts, etc.
 
    Operating Principle
The air is filtered and heated into the air distributor at the top of the dryer. The hot air spirally enters the drying chamber. The feed solution is passed through the high-speed centrifugal atomizer at the top of the tower body and (rotated) is sprayed into very fine mist of droplets, which can be dried into finished products in very short time in parallel flow with the hot air. The finished product is continuously output from the bottom of the drying tower and the cyclone separator, and the exhaust gas is evacuated by the induced draft fan.
 
Product Feature
   The drying speed is fast, and the surface area of the feed liquid after atomization is greatly increased. In the hot air flow, 95%-98% of water can be evaporated instantaneously, and the drying time is only a few seconds, especially suitable for drying of thermal sensitive material. The product has good uniformity, flowability and solubility, and the product has high purity and good quality. The production process is simplified and the operation and control are convenient. For liquids with a moisture content of 40-60% (up to 90% of special materials), the liquid can be dried into powder products at one time. After drying,  it will not need to be crushed and screened, which reduces the number of production processes and improves product purity. It is convenient to adjust, control and manage the particle size, loose density and moisture in a certain range.
 
Fluidized bed dryer is a kind of stirring equipment with fluid mixing and special form of steelmaking equipment.
 
Chinese Name
Fluidized bed dryer   Bed height 300~400mm   Air velocity 1.2tn/s    Intake air temperature 150~1601
 
Advantages
   The drying speed of the fluidized bed dryer is very fast, the temperature in the fluidized bed is uniform, and it is easy to control and adjust, and the time is also relatively easy to select. Therefore, a dry material with extremely low moisture content can be obtained.
 
Classification
   Fluidized bed drying equipment has three major categories: continuous, semi-continuous and intermittent production. According to the structure, there are various forms like single layer, multi-layer, horizontal multi-chamber pulse, cone and jet, vibration and inert carrier, etc. . When using this dryer to dry the ammonium oxide, the exhaust temperature is 50-60, the negative pressure operation, the material particle size is 250-420, and it stays 120S in the machine.

Operating Principle
   Fluidized bed dryers are used to place flowable materials such as powders, granules (or even suspensions and solutions) on a gas flow distribution plate such as a perforated plate, and send a drying medium having a considerable speed from the lower part thereof. When the flow velocity of the medium is low, the gas flows between the particles of the material, and the entire material layer does not move; gradually increasing the velocity of the gas, the material layer begins to expand, the gap between the particles increases, and then the velocity of the gas stream increases, and a considerable part of the material is suspended and forms gas-solid mixed bed, that is fluidized bed, because the material suspended in the fluidized bed resembles boiling liquid, it is also called boiling bed, and it presents property of fluid in many aspects, for example, it has a clear upper interface and maintains the level; If you increase the airflow velocity, particles are almost all taken away by the airflow, it becomes gas delivery. Therefore, the gas flow rate is the most fundamental controlling factor of the fluidized bed dryer. The appropriate gas flow rate should be between the fluidization of the material layer and the outflow of the material.
 
Heat exchange in fluidized bed can be carried out by external jacket or bed heat exchanger.. When using in-bed heat exchangers, in addition to considering the general requirements of heat exchangers, it must also consider the impact on the flow of the material in the bed, that is, the form and installation of the heat exchanger should be as much as possible to facilitate the normal flow of fluids. It has been proved by practice that, when using a tube heat exchanger, 2/5 semi-viscous muddy material with high moisture content placed on the center of the equipment are difficult to disperse and fluidize in the drying medium flow.
Put some inert carrier (such as quartz sand, alumina, oxidized globules, particle salts, etc.) at the bottom of the dryer, when they are fluidized under the action of air currents with a certain flow rate, the wet material will adhere to the surface and then make it a dry shell. As the inert carriers collide with each other, the dry shell is detached and is carried away by the medium flow, and the carrier itself is brought into contact with the new wet material to form a dry shell. This cycle allows fine wet viscous material to also be fully dried in a fluidized bed dryer.
 
 
 
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