The hot air drying method is also known as the air-drying method. At present, the vast majority of domestic pulp molding products production are using the hot air drying method, it is in the specific pulp dryer machine to dry the paper molding products with hot air as the drying medium. The pulp dryer machine used is mainly an intermittent drying box (room) and continuous working chain dryer, etc. The working characteristics of the drying box (room) of the pulp dryer machine are intermittent drying, although the structure of the equipment is simple, the production efficiency is low, the drying temperature is not easy to control, and the utilization rate of the heat source is not high. The other type of pulp dryer machine is the widely used continuous dryer. The main body of this pulp dryer machine is a rectangular drying tunnel surrounded by rock wool insulation materials, and the interior is equipped with a multi-layer transport machine driven by a chain. The width and length of the drying tunnel can be determined by the size of the wet paper mould embryo and the required drying strength.
The moisture content of the wet molds entering the drying tunnel of the pulp dryer machine should be 65%-70%. The wet molds are automatically blown down to the conveyor belt of the drying tunnel by the transfer mold of the forming machine and move with the conveyor belt. The hot air blew in at the bottom of the chain belt during operation evaporates and dries the wet moulds. The drying time can be determined by adjusting the speed of the conveyor belt according to the heat balance calculation. In order to remove the evaporated water vapor from the wet moulds in time, the drying tunnel of pulp dryer machine is equipped with a corresponding exclusion device. The drying temperature in the drying tunnel can generally reach 105-200 degrees. No matter what kind of pulp dryer machine is chosen, the equipment itself is required to have a good insulation layer to prevent heat loss. The structure of the equipment should be able to ensure a uniform temperature in all parts of its interior. Hot air can be obtained in two main ways, one is to use the hot air oven to generate hot air directly by combustion, the other is to use steam to generate hot air by heat exchange with the air through a heat exchanger. Hot air is used as the drying medium in the drying tunnel and the heating source can be coal, oil or gas.