Pulp molded drying equipment

There are many ways to dry pulp model products. In addition to direct use of sunlight to dry, according to whether the drying time is demolded, it can be divided into demolding drying and in-mold drying; according to the different heat sources used during drying, it can be divided into hot air convection drying, far infrared radiation drying, microwave heating drying, direct heating and pressurization drying in the mold, etc. Demolding drying is the main drying method for pulp model industrial packaging products. According to the equipment used in the drying process, it is divided into drying box (room), tunnel (drying tunnel) dryer and chain dryer. Regardless of which drying equipment is used, the drying mechanism is basically the same. At present, the most common are drying tunnel drying and in-mold heating drying.

Drying tunnel pulp molded drying equipment

(1) Hot air drying
Hot air drying is also called hot air drying. At present, the majority of domestic pulp model products are produced by hot air drying, which uses hot air as the drying medium to dry pulp products in a specific drying device. The equipment used mainly includes intermittent drying boxes (rooms) and continuous chain dryers. The working characteristics of drying boxes (rooms) are intermittent drying. Although the equipment structure is simple, the production efficiency is low, the drying temperature is difficult to control, and the heat source utilization rate is not high. Another widely used type is the continuous drying tunnel. Its main body is a rectangular drying tunnel with several barrels of insulation material around it, and a multi-layer conveyor driven by a chain is installed inside. The width and length of the drying tunnel can be determined by the size of the wet cardboard and the required drying intensity.

Drying tunnel drying is coordinated with the pulp model dry pressing production process, and belongs to the out-of-mold drying (demolding drying) method; in-mold heating drying is coordinated with the pulp model wet pressing production process, and belongs to the in-mold drying method.

When using a drying tunnel dryer to dry wet cardboard, the moisture content of the wet cardboard entering the drying tunnel should be between 65% and 70%. The wet cardboard is automatically blown off by the transfer mold of the forming machine onto the conveyor chain of the drying tunnel dryer and moves with the conveyor chain. During the operation of the chain belt, the hot air blown in from the bottom evaporates and dries the wet cardboard. The drying time can be determined by adjusting the running speed of the conveyor chain belt according to the results of the heat balance calculation. In order to remove the water vapor evaporated from the wet cardboard in time, a corresponding removal device is provided in the drying tunnel. The drying temperature in the drying tunnel can generally reach 105~200℃. Regardless of the drying equipment selected, the equipment itself is required to have a good insulation layer to prevent heat loss, and the equipment structure must be able to ensure that the temperature of each part inside is uniform. Hot air is mainly obtained in two ways, one is to directly generate hot air by burning a hot air furnace, and the other is to use steam to exchange heat with air through a heat exchanger to generate hot air. Hot air is used as the drying medium in the drying tunnel, and the heating source can be coal, fuel oil or gas.

The machine uses steam to exchange heat with air through a heat exchanger to generate hot air for drying wet cardboard. The required steam is provided by a boiler, and the air is provided by a blower. The two exchange heat to generate hot air, and the wet air in the drying tunnel is discharged by an exhaust fan.