【作者】 王铭华；

【导师】 郭庆杰；

【作者基本信息】 中国石油大学 ， 化学工程， 2008， 硕士

【摘要】 随着电子工业和信息高科技产业迅猛发展,电子电器设备的更新换代周期不断缩短,废旧电子产品的数量与日俱增。印刷线路板是各类电子产品的重要组成部分,组分复杂,含有塑料、难熔氧化物和金属等,具有数量多、危害大、潜在价值高等特点。因此印刷线路板的无害化和资源化处理成为化学工程和环境工程研究的重要方向。在内径56 mm、高1600 mm的冷态流化床实验装置上研究了不同粒径电路板塑料颗粒的流化特性,获得了粒径和颗粒类型对塑料颗粒流化特性的影响规律。实验结果表明,电路板塑料颗粒为A类颗粒时,粘性力大,流化性能较差,具有拟C类颗粒的流化特性;电路板塑料颗粒为B类颗粒时,随着粒径的增大,最小流化速度也增大。B类颗粒用Ergun公式得到的结果比其他公式更接近实验结果,分别为实验结果的94.5%, 114%和91.8%,A颗粒3种公式的计算结果与实验结果相差很大,根据流化床中粘性颗粒的受力分析,提出了力平衡模型。同时发现对于电路板B类颗粒,不同含量的电路板和石英砂双组分混合物在相同的气速下,随着电路板含量的增加,电路板的混合指数变小。相同含量的电路板和石英砂双组分混合物随着气速的增大,电路板的混合指数变大。采用积分法对电路板中塑料颗粒的热解动力学行为进行了研究。废弃印刷线路板的热重分析以DTG曲线上的两个热解峰值为界,热裂解第二阶段的活化能比第一阶段大很多,需要更多的热量才可以进行。从红外谱图上可以发现:热解温度为316.1℃和349℃下芳香族物是挥发物的主要成分;三个温度下热解挥发物质中都含有C-O,并且都含有C-Cl;这个结论是合乎逻辑的,因为环氧树脂由双酚A和环氧氯丙烷耦联的结构中包含有芳香族化合物。在流化床反应器中热解电路板塑料颗粒,采用元素分析和傅里叶变换红外光谱等方法分析所收集的高沸点液体和固体的性质。结果表明,当温度和气速分别升高时,液体产品的收率也随之升高。热解油主要成分是芳烃,含有羟基、C=C、S=O和苯的取代官能团,热解固体产物主要成分是碳和玻璃纤维。对于电路板颗粒床层底部比床层顶部的压力波动幅度和方差大。随着气速的增大,电路板塑料颗粒和SiO2颗粒床层顶部和底部的压力波动幅度减小,方差也随之减小。CaCO3颗粒间的粘性力较大,不能流化,方差出现较大的波动。气速越大,形成的沟流越稳定,方差减小。在流化床时压力波动幅度增大,气泡的行为起了重要作用压力,波动信号的频率表现为低频率。在沟流时压力波动的幅值很小,使得压力波动信号的主频位于高频区域。更多还原

【Abstract】 With the development of information technologies, the amount of waste electrical and electronic equipments (WEEE) continues to increase rapidly due to limited service life. Printed circuit board (PCB) is an important part of electrical and electronic equipments. It includes plastic, refractory oxides and metals, which is characterized by an abundance of quantity, hazard effect to human health and high commercial value. Accordingly, the recovery of PCB is an important research project in the fields of chemical engineering and environmental engineering.The experiments were carried out in a fluidized bed of 56 mm in diameter and 1600 mm in height to determine the fluidization characteristics of different diameter scrap printed circuit board particles. Experimental findings showed that the fluidization characteristics of scrap printed circuit board particles depended on the average sizes and type of particles. The scrap printed circuit boards particles, belonging to Geldart A group with strong viscous force, whose fluidization features were similar to those of Geldart C, was difficult to fluidize. The scrap printed circuit board particles belonged to Geldart B and the minimum fluidization velocity increased as the average size increased. It has been found that the minimum fluidization velocities calculated by Ergun equation approached 94.5%, 114% and 91.8% of experimental minimum fluidization velocities for the particles of Geldart B group. For scrap printed circuit board particles, belonging to Geldart A group, the minimum fluidization velocities calculated by equations were smaller than experimental minimum fluidization velocities, and a model of force balance about cohesive particles was developed to evaluate fluidized characteristics. For scrap PCB particles belonging to Geldart B group, the mixture degree decreased when the mixture composition of scrap PCB particles and sands increased under the same superficial velocity. The mixture degree increased when the velocity increased under the same mixture composition of scrap PCB particles and sands. Thermal kinetic behaviors of scrap printed circuit boards were investigated using integral method. Pyrolysis process was divided into two stages characterized by DTG curve. The activation energy of the first stage was greater than it of the second stage. Because bisphnol A and epichlorohydrin contained aromatic compounds, aromatic hydrocarbon was the main composition at 316.1℃and 349℃in TG-FTIR, and the volatile compound contained C-O and C-Cl function under different temperatures from infrared spectra.The fluidized bed reactor was used to pyrolyze scrap printed circuit boards particles in inert gas conditions, and the high boiling liquid and solid products were analyzed using elemental analyzer and FTIR. The liquid content increased with increase in temperature or gas velocity. The main composition of liquid products was aromatics compounds which contained O-H, C=C, S=O and substituted functional group of benzene. The solid products contained carbon and fiberglas.Pressure fluctuation range and variance of PCB particles from top bed were larger than those from down bed. When the gas velocity increased, pressure fluctuation range and variance of PCB particles and SiO2 particles decreased. CaCO3 particles with strong viscous force was difficult to fluidize, whose variance fluctuation was large. When the gas velocity increased, the channeling stabilized and the variance decreased. Pressure fluctuation range increased owing to the ascending and coalescence of bubbles and the major frequency of pressure fluctuation signals was small in the fluidized state. Pressure fluctuation range decreased and the major frequency of pressure fluctuation signals was high in the channeling.更多还原