Dryer aerodynamic. The principle of action and advantages.

The main factor of production quality, in granulation and briquetting of any type of biomass is appropriate preparation of raw materials grinding, drying, removal of impurities. If the removal of impurities, through screening, and измель value, by crushing of raw materials, are quite simple, those process of drying of moist materials to the required moisture content, is the most responsible and difficult process. The main purpose of the process of drying of organic waste, sawdust, shavings, wood chips, bark, straw, lignin, peat, and other materials that can be used as energy, increase their caloric value and feeding of raw materials with optimal humidity, producing quality pellets and briquettes in their production.

The process of drying is the removal of materials of moisture by evaporation and discharge resulting vapours. Classified dryer, mainly, by the method of heat to the surface of the dried material. Distinguish contact, convection, radiation, institutional, high-frequency and combined dryers. To disperse materials are the most effective convective dryer, in which there is a constant contact of drying agent with the surface of the particles of processed waste, peat etc.

As a drying agent is applied heated air or flue gases. To obtain a «clean» product use flue gas is unacceptable, therefore, drying equipment must have a heat exchanger in which heats the air. Drying speed depends on the temperature of drying agent, relative speed of its movement, a specific surface particles, physical properties of the material.

In the initial period (period of constant speed of drying moisture of material is constant in the whole volume. After a period of drying time, when the concentration of moisture by evaporation at the surface of the material decreases, moisture begins to move from the center of the particles to the surface due to the concentration gradient, there is a period of falling speed of drying, the material temperature begins to rise. At least reduce the moisture content of the material, the temperature of the dried particles approaches to the temperature of drying agent.

Thus, there is a limit temperature applied drying agent, in connection with the possibility of ignition of fine dry particles of the material used.

In rotary dryers temperature of drying agent reaches 400 OC, which may cause the ignition of dried raw materials. Drum inert, its running time consuming, the process of drying is hard in control. Aerodynamic dryer works at the temperature of drying agent 120 - 150 C, which eliminates the risk of fire drained particles. Start the dryer for a few minutes, the drying process easy to manage and control. Material drying in the vertical wind tunnel is ensured by intensive mass-air exchange, which is the result of a technical solution of this unit. Also, the drying process is accelerated in connection with the intense friction particles together in a dense layer, while driving with high peripheral speeds.

Speed of drying agent regarding the particles of the material in the wind tunnel dryer is 25 - 28 m/s, that allows to dry wood and agricultural waste, peat, lignin and other fine materials in a compact design, which occupies a small space that has low metal content. Duration of drying and energy consumption, by drying in the pulse fluidized bed is significantly lower than in vacuum dryers.

Dryer aerodynamic