WORKING PROCESS
The materials enter the machine from the feed port. Under the action of vibration force, the materials are thrown forward in a horizontal direction and move continuously. After the hot air passes upward through the fluidized bed and exchanges heat with the wet materials, the wet air is discharged by the exhaust after being dedusted by the cyclone separator (or pulse bag filter), and the dry materials are discharged from the discharge port, and then collected and packaged.
PRINCIPLE
If a material layer is placed in the vibration space, the following phenomena will appear: at first, the material layer is gradually compacted with the increase of vibration acceleration; When the acceleration value is close to the gravity acceleration (9.81m / S2), the material layer density reaches the maximum; If the vibration acceleration is further increased, the material layer begins to expand and the so-called vibration fluidization state appears. At this time. The materials placed on the vibrating surface produce strong mixing and are easy to move horizontally or obliquely. They can also be transported upward (or downward) along the spiral surface. Under this condition, if heat is input to the material layer by conduction, convection, radiation or a combination of both, the purpose of material drying can be achieved. [2]
A vibrating fluidized bed is to increase the vibration of the bed on the basis of material fluidization so that the materials have a process of throwing and loosening. The two are organically combined to achieve the fluidization effect of the low bed. It is different from the traditional fluidized bed dryer in that the material transportation and fluidization of the ordinary fluidized bed dryer are completely completed by wind (hot air), while the vibrating fluidized bed dryer is mainly completed by vibration force. It can reduce the minimum fluidization speed of materials, especially the particles near the bottom that fluidizes first, improve the fluidization quality of particles at the bottom, and enable some materials that are difficult to fluidize to carry out normal drying operations.
DESCRIPTION
In a fluid bed dryer, good contact between hot air and particles to be dried so obtained which causes rapid drying.
Theory:
If gas is allowed to flow upwards through a bed of solids particles at a velocity greater than the settling velocity of the particles, the particles are partially suspended in the gas stream.
The resultant mixture of solids and gas behave like a liquid and the solids are said to be fluidized. Each individual solid particle is surrounded by the drying gas with the result that the drying takes place in a much shorter period.
Mover over the intense mixing between the solids and hot provides uniform conditions of temperature, composition, and particle size distribution.
APPLICATION:
The fluidized bed dryer is suitable for drying, cooling, and humidifying various granular materials, crystals, and powder mixtures.
1. Pharmaceutical and chemical industry: various tablet granules, boric acid, borax, hydroquinone, various additives, etc.
2. Food and building materials industry: distiller's grains, monosodium glutamate, granulated sugar, salt, granular chicken essence, slag, bean seed, etc.
Equipment design conditions
Fluidized bed operation has the advantages of good mixing of solid particles and large surface area of heat and mass transfer between gas and solid, but its main shortcomings are:
1. The treated particles should be greater than 50 ~ 100 μ m. Otherwise, it is easy to form gully flow and stagnation zone;
2. When the particle size distribution is wide, the entrainment is serious
3. When the particle temperature is high, it is easy to form agglomeration or agglomeration;
4. For nonspherical particles such as wheat grain, fiber, and slice, they can not fluidize well.
A vibrating fluidized bed is a successful modified fluidized bed. It is a fluidized bed supported on a group of springs and powered by an exciting motor. The bulk materials put into the dryer are thrown to the outlet end and output to the VI end under the action of exciting force on the perforated plate. The hot air is blown under the perforated plate and passes through the material layer to transfer the heat to the material, and the water vaporized from the material is discharged from the exhaust port to dry the material. Because the materials are in motion under the action of mechanical vibration in the vibrating fluidized bed, dynamic drying can be achieved only by blowing in an appropriate amount of hot air. Therefore, the thermal efficiency is high and the materials are dried evenly.