The principle of Yankee hood is mainly based on contact drying and convection drying:
Contact drying principle
The surface temperature of the Yanke cylinder is high, and when the paper web is in contact with the surface of the Yanke cylinder, the heat is transferred from the Yanke cylinder to the paper web, so that the water in the paper web is evaporated. At the same time, the high-speed rotation of the Yanke cylinder drives the paper web to move, so that the paper web is constantly in contact with the new high-temperature cylinder surface, and continuous heat transfer and water evaporation.
Convection drying principle
1. High-speed hot air impact: the hood is equipped with a special air duct and nozzle, which can produce high temperature and high-speed hot air. The hot air blows vertically to the surface of the web at a certain Angle and speed, destroying the air film on the surface of the web, greatly increasing the heat and mass transfer coefficient, and strengthening the evaporation process.
2. Zone drying: The gas hood is usually divided into three independent areas, namely, the high temperature toe zone, the mixing zone and the drying zone in the first zone after pressing. The temperature in different areas can be adjusted according to the paper quality and yield requirements. High temperature toe area provides higher temperature, rapid evaporation of a lot of water; Mixing zone temperature is moderate, further drying and adjusting paper properties; The drying zone ensures that the paper meets the final drying requirements.
3. Hot air recycling: Some Yanke gas hoods also have hot air circulation system, which will treat the discharged hot and humid air and recycle it to improve energy efficiency and reduce production costs.
Shandong Fengxin Technology Development Co., Ltd. is a company specializing in the development, research and production of paper ventilation, drying, energy saving technology and equipment, and has achieved good results in the field of paper ventilation, drying and energy saving for many years. Fengxin closed air hood system design mainly includes the drying part closed air hood, air hood in various functions of the blower, waste heat recovery device, paper machine mesh moisture, high-speed Yanke hot air hood, all kinds of coating drying boxes, workshop ventilation system and supporting equipment.