A coal dryer is an industrial drying device specifically designed to reduce the moisture content of coal. Coal carries a significant amount of moisture during mining and washing. Excessive moisture not only increases transportation costs but also reduces combustion efficiency and can even lead to mold growth or spontaneous combustion during storage. Coal dryers use thermal drying to control the moisture content of coal within a reasonable range, thereby improving the quality and economic value of the coal.
Coal drying offers several benefits. First, it increases the calorific value; for every 10% reduction in moisture, the calorific value can increase by approximately 700 to 1000 kcal. Second, it reduces transportation costs; removing ineffective moisture reduces the tonnage required for transport. Third, it improves combustion efficiency; lower moisture content coal burns more completely. Fourth, it prevents storage deterioration; controlling moisture effectively inhibits microbial activity and the risk of spontaneous combustion.
The equipment mainly consists of a heat source, belt feeder, rotary drum, belt discharger, induced draft fan, dust removal system, and power distribution control system. For flammable materials such as lignite, a nitrogen or carbon dioxide oxygen concentration monitoring and explosion-proof safety system is also required.
Its working principle is as follows: After wet coal enters the drum, it passes through three working zones along the drum's axial direction. The first is the guiding zone, where the material comes into contact with high-temperature hot air, and surface moisture evaporates rapidly. The second is the lifting plate zone, where the lifting plates lift the material to form a uniform material curtain, ensuring full contact between the material and the hot air, and stripping away internal and external moisture. The third is the discharge zone, where the dried material rolls and slides to the discharge port for discharge. The rotation of the drum continuously agitates the material, ensuring thorough and uniform heat exchange.
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