多晶硅还原炉尾气系统磨损研究

发布时间：2018-05-11 16:08

本文选题：硅颗粒 + 尾气系统　；参考：《中国矿业大学》2015年硕士论文

【摘要】：多晶硅生产是光伏能源和微电子工业的基础产业,占据化学工业重要位置,主流多晶硅生产技术—改良西门子法是涉及有毒、易燃、易爆介质的化工联产过程,生产安全性倍受行业关注。实际多晶硅生产中还原尾气携带大量硬质硅颗粒排出还原炉,造成尾气系统过流部件持续冲蚀,成为多晶硅生产的重大安全隐患。然而,还原尾气系统管路冗长,结构复杂,生产现场又缺乏尾气系统过流部件磨损认识,因此尾气系统抗磨防护工作的开展困难重重。本文基于气固两相流动理论和冲蚀理论,从化工安全角度出发,利用数值模拟方法,对过流部件的磨损状况进行预测,并探究工况对局部磨损的影响规律。在此基础之上,结合还原炉尾气系统生产特点,从主动防护与被动防护的角度,对系统过流部件进行磨损治理,指导生产实践,消除多晶硅还原炉尾气系统中的磨损安全隐患。硅颗粒和尾气理化性质分析表明:硅颗粒成分几乎全部为无定型硅,微量参杂晶体硅;为硅气相外延体反应、Si HCl3和Si H2Cl2热解反应、温度波动以及生产系统运行不稳定等客观原因导致产生。研究以尾气出口管道为对象,确定了8个与支管对应的环管底部区域,2个位于环管出口两侧上方位外侧22.5°区域,4个位于单炉主管上下方位壁面区为严重磨损区域;发现前8个局部磨损区域为硅颗粒高冲角碰撞所致,后6个区域为低冲角、高速磨蚀引起,单炉主管上方位壁面磨损最为严重。探究工况影响规律发现:尾气速度增加,局部磨损率最大值以指数规律增长;硅颗粒直径增加,磨损区域变化并出现“粒度效应”,局部磨损率最大值增加幅度越来越小。硅颗粒浓度增加,局部磨损率最大值增加幅度越来越大,但两个局部出现“屏蔽效应”,增加幅度越来越小。以尾气汇流管道为对象深入,确定了汇流管道磨损由低冲角磨蚀造成,局部磨损区域位于有支管接入的三通下游壁面,其中下方位壁面磨损比上方位严重,外侧壁面磨损比内侧壁面严重;支管和上游壁面几乎不发生磨损。探究工况影响规律发现:尾气速度增加,磨损局部向两侧移动,局部磨损率最大值以指数规律增长;硅颗粒直径增加,磨损区域跨方位变化,整个三通单元磨损率最大值线性增长;硅颗粒浓度增加,局部磨损率最大值近乎线性规律发展。主、支管流量比例增加,磨损局部由支管正对壁面向下游发展,整个三通单元磨损率最大值增加幅度越来越大。此外,提出减少硅颗粒产生的生产过程优化,采取炉内大颗粒尾气工装拦截与炉外小颗粒金属过滤除尘的硅颗粒净化,以及单炉主管的气动肋条抗磨措施进行主动防护;选择以高锰钢焊条堆焊的涂层抗磨,与汇管局部外加耐磨衬块的厚度补偿方式进行被动防护。同时,制定局部磨损区域厚度监测方案。
[Abstract]:Polysilicon production is the basic industry of photovoltaic energy and microelectronics industry. It occupies an important position in the chemical industry. The mainstream polysilicon production technology, the modified SIEMENS method, is a chemical co production process involving toxic, flammable and explosive medium. The production safety is paid much attention by the industry. In actual polycrystalline silicon production, the reduction tail gas is carried a large amount of hard silicon particles The discharge reduction furnace, which causes the continuous erosion of the overcurrent components of the exhaust system, has become a major safety hazard in the production of polysilicon. However, the pipeline of the reduction tail gas system is long and complex, and the production site lacks the understanding of the wear and tear of the overflow components in the exhaust system. Therefore, the anti-wear protection work of the tail gas system is difficult to carry out. This paper is based on the gas-solid two-phase flow. The theory and erosion theory, from the point of view of chemical safety, use the numerical simulation method to predict the wear condition of the overcurrent components and explore the effect of the working condition on the local wear. On this basis, the wear and tear of the system overcurrent components are treated from the angle of active protection and passive protection by combining the production characteristics of the exhaust system of the reduction furnace. In order to guide the production practice and eliminate the risk of wear safety in the exhaust system of the polysilicon reduction furnace, the analysis of the physical and chemical properties of silicon particles and tail gas shows that the silicon particles are almost all amorphous silicon, micro mixed crystal silicon, the reaction of silicon gas phase epitaxy, the reaction of Si HCl3 and Si H2Cl2, the temperature fluctuation and the unstable operation of the production system, etc. The objective causes result. The study takes the tail gas outlet pipeline as the object, and determines the bottom area of 8 ring tube corresponding to the branch pipe, 2 locates in the azimuth 22.5 degree area on the two sides of the ring tube outlet, and the 4 are located in the upper and lower azimuth wall area of the single furnace, and the first 8 local wear regions are caused by the high impact angle collision of silicon particles. The latter 6 regions are low impact angle and high speed abrasion, the most serious wear of the single furnace head is on the azimuth surface. It is found that the rate of tail gas increases, the maximum value of the local wear rate increases exponentially, the diameter of the silicon particles increases, the wear area changes and the "grain effect" appears, and the maximum increase of the local wear rate is increasing. The smaller the concentration of silicon particles increases, the maximum increase of the maximum local wear rate is increasing, but the two local "shielding effect" is more and more small. Taking the tail gas flow pipe as the object, it is determined that the wear of the pipeline is caused by the low impact angle abrasion, and the local wear area is located in the downstream wall of the three pass with a branch pipe. The wear of the lower azimuth surface is worse than that of the upper wall, and the wear of the outer wall is more serious than that of the inner wall, and there is almost no wear on the branch pipe and the upper wall. The maximum wear rate of the whole three pass element increases linearly, the concentration of silicon particles increases and the maximum of the local wear rate is almost linear. The proportion of the flow rate increases, the wear part is developed from the straight wall of the branch pipe to the downstream, and the maximum increase of the wear rate of the whole three passage element is increasing. Furthermore, it is proposed to reduce the production of silicon particles. The production process is optimized, which adopts the silicon particle purification of the large particle tail gas tooling in the furnace and the small particle metal filtration and dust removal outside the furnace, as well as the anti wear measures of the pneumatic ribs in the single furnace, selecting the coating anti wear with the high manganese steel welding electrode and the passive protection with the thickness compensation mode of the local external wear lining block. Set up a regional thickness monitoring scheme for local wear.

【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X76;TQ127.2

【引证文献】