Airflow and normal flow of fluidized bed dryer

- Oct 22, 2018-

The fluidized bed dryer has a fast drying speed. During the operation, the temperature in the fluidized bed is uniform and easy to control, and the time is also easy to select during operation, so that a dry material having a very low water content can be obtained. Fluidized bed drying equipment has three major categories: continuous, semi-continuous, and intermittent production. According to the structure, there are single layer, multi-layer, horizontal multi-chamber pulse, cone and spout, vibration and inert carrier.


In a fluidized bed dryer, a liquid material such as a paste or a powder is placed on a gas flow distribution plate such as a perforated plate, and when it is used, mainly the lower portion thereof is fed with a drying medium having a relatively high speed, and when the medium flow rate is low, At the same time, the gas flows between the particles of the material, and the entire material layer does not move; the gas flow rate is gradually increased, the material layer begins to expand, and the gap between the particles increases.


The fluidized bed dryer can increase the gas flow rate. During operation, a considerable part of the material will be in suspension, so that the gas and solid mixed bed, ie the fluidized bed, can be directly formed, because the suspended material in the fluidized bed is very similar. Boiling liquid, also known as a fluidized bed, and it exhibits fluid properties in many ways.


If the fluidized bed dryer increases the flow velocity of the gas, the particles are almost completely carried away by the gas flow, so that the gas can be transported to a certain extent. Therefore, the velocity of the gas flow is the most fundamental controlling factor of the fluidized bed dryer. A very suitable gas flow rate at the time of use should be between the beginning of the fluidization of the material layer and the bringing of the material.


The fluidized bed of the fluidized bed dryer can be directly passed through the outer jacket or the in-bed heat exchanger. In addition to the requirements of the general heat exchanger, it must be considered to some extent. The effect of the flow of material in the bed, ie the form and installation of the heat exchanger, should be as beneficial as possible to the normal flow of the fluid.


When the fluidized bed dryer fluidizes under the action of a certain flow rate of air, it will need to adhere its wet material to the surface, so that it can become a dry outer shell, because the inert carriers collide with each other, The dry outer casing will fall off and be carried away by the flow of the medium; the carrier itself will come into contact with the new wet material and form a dry outer casing. This cycle allows the fine wet-adhesive material to be sufficiently dried in a fluidized bed dryer.