废弃印刷线路板热解过程传热特性实验研究

为了改善印刷线路板热解过程中的传热性能、提高废弃印刷线路板热解效率和产率、减少热解过程对环境的二次污染,本文设计并搭建了一套固定床热解实验装置,在高温氮气渗流条件下对3种不同尺寸废弃印刷线路板颗粒料层的热解过程进行了对比实验;测试了颗粒料层热解过程沿轴向和径向的温度分布,分析了线路板颗粒尺寸对物料层温度场和对热解区域迁移速度的影响,阐明了沿热解炉高度方向物料温度参数随时间的变化特征,揭示了热解区域和热解状态对于沿轴向的温升速率和温度梯度的影响规律.结果表明:较大颗粒料层的热解区域纵向迁移速度要快于小颗粒料层,当颗粒尺寸分别为1.5、2.5和3.5 cm时,热解区域的纵向迁移速度分别为0.47、0.50和0.63 m·h~(-1);热解区域和热解状态对于沿轴向的温升速率和温度梯度有显著影响;废弃印刷线路版热解过程的能源利用效率较低,只有29.50%～37.13%,主要损失为热解装置和物料的蓄热损失.研究结果对印刷线路板热解装置的设计和运行具有重要的指导意义.

Experimental investigation on the heat transfer characteristics of waste printed circuit boards during pyrolysis

In order to improve the heat transfer performance, increase the efficiency and yield of waste printed circuit board and reduce the secondary pollution to the environment during the pyrolysis process, a fixed bed device was developed to investigate pyrolysis under high temperature nitrogen flow. The temperature distribution along the axial and radial directions of waste Printed circuit boards (PCBs) particles layer was measured, the influence of PCB particle size on the temperature field of material layer and the migration velocity of pyrolysis zone were analyzed, the temperature variation along the axis with time are explained, the effect of pyrolysis region and pyrolysis state on the temperature rising rate and temperature gradient along vertical direction has been revealed. The experimental results indicated that the size of the PCB particle has an obvious effect on the pyrolysis reaction time and the migration rate of pyrolysis. The larger the particle size is, the shorter the pyrolysis reaction time is and the faster the migration rate is. When the square particle sizes are 1.5, 2.5 and 3.5 cm wide, the average migration rates of pyrolysis reaction zone along the vertical direction are 0.47, 0.50 and 0.63 m·h^-1, respectively. Pyrolysis region and pyrolysis state have obvious effect on the temperature rising rate and temperature gradient along vertical direction. The energy utilization efficiency of waste printed circuit board pyrolysis process is relatively low, only 29.50%~37.13%, and the main loss is heat storage loss of pyrolysis device and material. The research results have important guiding significance for the design and operation of printed circuit board pyrolysis equipment.