Radiation-convective conveyor drying of basalt - bentonite cardboard

Abstract

The manuscript presents the results of the research of the kinetics of radiation drying of basalt-bentonite cardboard. It has been established that in the case of high-temperature radiation drying of cardboard, the value of the reduced first critical moisture content in the area with low values – 0.17 is observed; compared to the same indicator for convective drying of slabs 50 and 100 mm thick - 0.41 and 0.20, respectively. This feature of the process allows you to raise the temperature in the first drying chamber to 570-600°C without fear of local overheating of the material. It was noted that at the stage of the falling drying speed, which is largely implemented in the second drying chamber, in order to avoid local overheating of the material, the temperature in the chamber is limited to 440°C. The decrease in the temperature level of the process in the second drying chamber is compensated for by the active gas-dynamic environment, in which the average speed of the drying agent in the inlet action zone can reach values of ± 5 m/s. The results of the controlled operation of the pilot conveyor drying installation are given. Its satisfactory specific energy indicators are noted, which for the same type of installations can reach values of 1200-2000 kcal/kg of moisture. In conclusion, it is noted that, in addition to the traditional positions of the heat balance of the plant, an energy-efficient modernization of a conveyor drying plant should include reducing losses with a spent drying agent, with recuperative losses through walling structures, with unorganized gas exchange in the drying chamber, and such positions as efficient drying agent with the optimization of its gas dynamics in the drying chamber.