振动流化床干燥分区供热方式研究

New Divisional Heat Supply Modes for Coal Drying in a Vibrated Fluidized Bed

基于由小试结果回归得到的煤炭振动流化床干燥动力学数学模型及传热方程、热平衡方程,建立了煤炭表面水干燥所需热量在振动流化床干燥机长度方向上变化的数学模型,该模型表明,煤炭表面水干燥所需热量沿干燥机长度方向呈负指数急剧减少.根据这一特点,讨论了干燥机长度方向等速不等温进气、等温不等速进气、不等温不等速进气3种分区供热方式.采用床面积为1200mm×200mm的振动流化床干燥机进行了中间试验,结果表证明,所得模型与试验结果相符,即采用分区供热方式可降低干燥机出口气体温度和干燥能耗.

A mathematics model to predict the heat demand for the vaporization of coal surface moisture along the length of a vibrated fluidized bed dryer was developed. The model shows that the heat demand for the vaporization of coal surface moisture decreases exponentially along the drier length. According to this characteristic, three divisional heat supply modes such as unequal inlet gas temperature with equal inlet gas flow rate, unequal inlet gas flow rate with equal inlet gas temperature, and unequal inlet gas flow rate with unequal inlet gas temperature along the dryer length are discussed. Pilot test results from a vibrated fluidized bed dryer with a cross section of (1 200) mm×200 mm show that the model agrees well with the tests, and the average outlet gas temperature of the dryer can be decreased and energy consumption can be reduced obviously by employing the divisional heat supply modes.