【作者】 周际东；

【导师】 许仲梓； 严生；

【作者基本信息】 南京工业大学 ， 无机非金属材料， 2003， 博士

【摘要】 水泥是世界上最主要的建筑材料，我国已年产7亿吨以上。水泥生产大量消耗能源、资源，吨水泥耗电100kWh左右，其中60％用于粉磨工段。水泥粉磨过程能耗极高而效率又极低，仅0.6～1.0％用于新增表面能。由水泥粉体附着形成的“过粉磨”现象普遍存在，导致粉磨电耗居高不下。水泥新标准实施促进了我国水泥产品质量的提高，但也迫使水泥细度降低、比表面积升高，不采取相应技术措施则会造成磨内工况条件进一步恶化，粉磨电耗大幅攀升。若设法使粉磨电耗降低5％，则每年可节电21亿kWh，按每度电价0.5元计，每年可节约粉磨成本近10.5亿元，再加上电厂减少向环境排放大量的粉尘、SO₂、CO₂等，减轻环境负荷效益明显。因此，提高粉磨效率、降低粉磨电耗具有十分重要的意义。 通过改进粉磨工艺或改变磨机结构，可降低粉磨电耗、提高粉磨系统产质量，但无法根除过粉磨现象。针对水泥粉磨过程中物料间受静电力、范德华力、表面张力等物理作用形成过粉磨现象，提出用具有相当反能量的物理场干扰恶化磨内工况条件的因素，打破由于过粉磨现象产生的恶性平衡，建立起一种有利于粉磨效率提高的新的动态平衡的物理干扰助磨技术概念。论文研究切入点是以物理电磁学基本理论研究水泥粉磨过程中细粉附着、集聚现象，旨在建立消除磨内“缓冲垫层”的干扰机制。 水泥粉体静电带电机理和危害研究尚属空白。论文首先应用固体表面接触起电机理，理论推导了水泥粉体静电产生机理；续而应用物理电磁学基本定理设计了系列水泥粉体静电量、静电泄漏性能、静电电压和粉磨筒体静电泄漏电流的实验测试装置，探明了水泥粉磨过程中的静电发生规律。研究结果表明：粉磨作业过程中的粉体静电量增加是水泥粉体附着于磨机筒体边壁、研磨体的主要原因，由此导致粉磨过程中的“缓冲衬垫”效应，从而降低了粉磨效率。温度、水泥粉体比电阻、物料水分对水泥粉体静电量大小影响很大，在水泥物料粉磨过程中添加助磨剂可以明显降低水泥粉体的比电阻，加速粉体静电泄漏，从而降低粉体总体静电量，提高粉磨效率。 论文应用静电感应原理对水泥粉体附着层进行理论诠释，证明了感应电荷层对粉体的吸引作用是粉体附着的主要原因，确立了水泥粉磨作业过程中过粉磨现象的形成机制，由此建立了带电水泥粉体的静电感应双电层附着模型。通过理论推理和对现阶段粉体静电消除装置的分析，确定对感应电荷层进行干扰和消除机南京工业大学博士学位论文摘要制应该是直接外加电场作用，进而运用电磁学高频电流趋肤效应理论建立了干扰粉体静电附着物理模型:由导体内迅变电场引起的涡旋电流产生电流趋肤效应，电流密度集中于磨机筒体内、外壁，可以有效地干扰或消除感应双电层;筒体内壁粉体附着层因干扰后可以增加研磨体与筒体的接触程度，通过冲击、摩擦接触作用达到间接干扰研磨体粉体附着效应，提高粉磨效率。 干扰粉体静电附着物理模型的建立为以物理电磁法提高水泥粉磨效率提供可靠的物理理论模型和实际操作依据，这就要求后续研制的物理助磨技术电磁脉冲装置（physieal·grind一aiding一teehnique一即paratus in generating eleetronie transientpulse，以下简称PG声LTA）输出具有电流脉冲随时间变化大、输出脉冲次数多的特点以产生趋肤效应。而这种极短暂瞬间电压或电流大幅变化的脉冲型瞬变现象是电力电子设备稳定正常运行之大忌，强烈冲击电子器件，增大了研究设计的难度。实验装置的研制以电容储能、恒压充电为主要思想，设计了以大功率开关器件IGBT为主要元器件的脉冲电流发生装置。运用PsPice电子线路仿真软件对设计线路和主要关键电子元器件进行仿真实验，线路仿真中以IKV恒压充电可以得到每秒100次的近300A瞬间脉冲电流，其中由分布电感、电容及工GBT自身寄生电感引起的反冲振荡对电路设计和开关器件选取具有可行性指导意义。PGAI叭选用ZooA的IGBT可以得到950V、280A、脉宽为10娜的迅变脉冲，与仿真结果较为吻合。 PGAI’A采用串联的双向可控硅和光电祸合器分段电压的设计，输出电压范围100一10O0v。放电回路采用桥式交叉电路，通过对驱动信号的软件控制实现了负载上放电脉冲的方向变化。根据充放电回路不同的要求对其驱动电路进行设计，充电回路中的IGBT采用EXB841，放电回路采用脉冲变压器驱动两路工GBT，提高了脉冲线路的稳定性。设计中由采样保持电路对电流脉冲峰值进行测量和实时显示，输出脉冲次数每秒1一100次，保证了在工业磨机上实际操作时合适的脉冲输出次数选取。PGATA采用单片机为控制器件，实现了液晶显示，键盘输入以及对系统实时数据的处理和显示等功能，可以实时显示PG户江人输出回路中的输出瞬变电流、磨机接触状态，从而对PGAI…A输出参数和回路电阻进行及时调整。采用C语言作为单片机的软件开发语言，优化了系统的软件设计。 PGATA研制成功为物理助磨技术可行性研究提供了可操作工具。实验首先设计并建立合理的物理助磨实验磨机粉磨操作系统。分别将稳恒直流电源和PG户n人的不同输出功率能量作用于实验磨粉磨系统中，对比有无趋肤电场存在的更多还原

【Abstract】 Cement is the most principal building material in the world. In China, its output has reached 700 million tons per year. Cement production process consumes large amount of energy and natural resources. At present, a ton of cement expends comprehensively about lOOkWh of electricity about 60% of which is used in grinding section, Cement grinding process consumes high energy on low efficiency, only 0.6 to 1.0 percent of which is being used in increasing surface. Owing to the universal existence of buffer bedding formatted by cement powder adherence, energy consumption is on a high level continuously. It is no doubt that the newly cement regulation put into effect will promote cement quality, on the contrary it forces the cement fineness down and surface area up. If no relevant technological innovation adapt, the consequences would be that mill’s condition take a turn for the worse leading to the increasing on grinding electricity cost. Supposing that electricity cost of cement grinding be cut down for 5%, the consequence is that 2.1 billion kWh of electricity, equivalent to 1 billion yuan, could be saved. Further more, a great quantity of dust, SO2, CO2 from power plant to environment will be reduced, so as to lessen load of environment. Therefore, saving the electricity of cement grinding is of momentous significance.By way of better the grinding technique and the mill construction could cut down grinding electricity cost, enhance the quality and quantity of mill system, but the phenomenon of excessive grinding should not be eliminated. Aiming at the phenomenon of excessive grinding formatted from physical action of electrostatic force, Van de wall’s force and surface stretching force among the ground stuff in cement grinding process, the dissertation put forward a conception of physical grind-aiding and interference technique. Based on the idea that the physical field matching with anti-energy should bring the action of interfering with the factors worsening working condition so as to break pernicious balance due to excessive grinding, a new kind of dynamic balance benefiting to up-grade grinding efficiency could be set up. The initial research on physical grind-aiding technology went through the fundamental theory of electromagnetism by which the phenomenon of powder particle adherence and gathering together in grinding process could be studied, so the mechanism of interfering buffer bedding should be founded.Up to now, no study on the cement powder electrification and its harmfulness is pursued. First of all, the cement powder electrification mechanism was deduced from the theory of solid-surface-contacting-electrification. Next, electrification regulation of cement powder was verified by using the series of experimental system specially built for the electrostatic charge of cement powder, performance of its leakage, electrostatic voltage. The results show that cement powder particle adherence to inner wall of mill’s thick and grinding bodies was reasoned from increasing of electrostatic charge of cement powder in grinding process. Therefore, the buffer bedding brought about from this led to decreasing on grinding efficiency. Temperature, cement risistivity, moisture content all are the effect factors on electrostatic charge of cement powder. The grinding-aids may obviously lower the cement risistivity, quicken leakage of cement electrostatic. As a result, electrostatic charge of cement powder reduced, and also grinding efficiency enhanced.The dissertation applied the principles of electrostatic induction for the theory explanatory of cement adherence layer, which proves attraction of the inductive electrostatic charge layer on the cement is one of the main reasons of cement adherence. The formation mechanism on the phenomenon of excessive grinding could formed and therefrom the cement adherence model of the inductive electrostatic double layer was built. By theory of electrostatic induction and analyzing the existing electrostatic-eliminated apparatus of powder, the direct additional electric field coul更多还原