Views: 7 Author: Site Editor Publish Time: 2019-07-24 Origin: Site
The drying method of the veneer is divided into two categories: natural drying and artificial drying. Various types of manual drying methods are used in general factory production. According to the transmission method, the dryer can be divided into a mesh belt type and a roller type. Mesh belt dryer, the veneer is placed between two layers of steel mesh through the dryer during transportation. Roller dryer, the veneer is held by the upper and lower rollers through the dryer during transportation.
Whether it is a roller dryer or a mesh belt dryer, each veneer dryer includes a drying section and a cooling section. The drying section is mainly used to heat the veneer, evaporate water, and circulate the water from the veneer by circulating hot air. The drying section is composed of several sub-chambers depending on the output, and each sub-chamber has the same structure. The longer the drying section, the faster the transfer of the veneer and the higher the production capacity of the equipment.
The function of the cooling section is to ventilate and cool the veneer during the process of maintaining the pressurized state. On the one hand, the stress in the veneer is eliminated, and the veneer is flattened; On the other hand, using a veneer surface layer temperature gradient to evaporate a portion of the moisture. The cooling section generally consists of one or two compartments.
Most of the veneer drying uses 0.4-1.0 Mpa of saturated steam or heat transfer oil as the heat source. The cold air is heated to 140-180℃ hot air through the radiator as a drying medium transferring heat to veneers. It can also directly burn gas, fuel, wood residues, etc. to heat the cold air. Hot air ventilation systems generally have a lateral and vertical division. Dryers with the same conditions use different ventilation methods, and the drying efficiency is very different.
The direction of the inlet of the dryer is divided into longitudinal and transverse directions. If the feeding direction is consistent with the fibre direction of the veneer, it is called the longitudinal feeding. General mesh belt dryers and all roller dryers use this feeding method. If the orientation of the board is perpendicular to the fibre direction of the veneers, it is called the transverse feeding. Mesh belt jet dryer adopts this type of feeding methods. The longitudinal feeding must cut the veneer into a single sheet for drying, and the transverse feeding can continuously dry the veneers of a roll.