【作者】 魏吴晋；

【导师】 林柏泉；

【作者基本信息】 中国矿业大学 ， 安全技术及工程， 2010， 博士

【摘要】 纳米结构通常是指尺寸在100纳米以下的微小结构,纳米技术其实就是一种用单个原子、分子射程物质的技术。这是由于纳米材料具有颗粒尺寸小、比表面积大、表面能高、表面原子所占比例大等特点,以及其特有的三大效应:表面效应、小尺寸效应和宏观量子隧道效应。美国国家科学基金会更统计出,在2010~2015年间全球纳米科技与材料的商机,估计有一兆美元左右。但是,纳米是把“双刃剑”,它表现出特殊的性质,具有全新的用途。然而,在2003年美国化学学会年会上,有3个研究小组发表了纳米材料具有特殊毒性的报告,却未对纳米的爆炸之安全特性进行研究。粉尘爆炸是工业企业防火工作中不可忽视的重要问题,中国每年都有发生粉尘爆炸事故,而且还常常属于重、特大火灾。在这些火灾中,最严重的是铝粉尘爆炸,铝粉是一个具有粉尘特质更具火灾爆炸之特性,值得进一步研究探讨。影响火灾或爆炸之因素中粒径与粒度分布与粒子形状与表面状态具关键性;纳米科技及技术是最新科技及产业,面临此纳米时代的来临,对其安全特性了解却十分所限,这是十分危险情况。没有安全作为基础,一但发生事故,其产业发展将受到束缚与限制发展;而没有了解纳米安全特性(包括:最小点火能量,最低爆炸下限,最大爆炸压力等),就无法有效作好本质安全的预防措施(如惰性化及耐爆)和损失控制(如泄爆,抑爆或隔爆);所以说这是预防性措施,更能体现安全是产业发展基础之理念,并章显安全设计重要性与应用性。目前,国内外研究包括针对煤炭方面(含煤尘及瓦斯)爆炸之研究,瓦斯爆炸方面之探讨,燃烧过程中的化学动力学特性的研究,瓦斯(可燃气体)爆炸传播规律研究,爆炸的数值模拟,铝粉爆炸,实验方法,火灾及爆炸控制措施在预防措施及限制损失均有所研究,但是没有对纳米铝粉的安全性进行研究。本文采用理论及实验相结合的研究方法对铝纳米(纳米)金属粉尘爆炸及其抑制技术开展研究。理论研究包括:燃烧与爆炸的理论基础,可燃气体爆炸机理,可燃固体的燃烧与爆炸机理,含碳粒的燃烧理论,可燃粉尘的爆炸机理,铝粉的燃烧与爆炸机理研究,含铝粉遇水燃烧机理及铝粉爆炸机理。实验设备主要是20升钢球爆炸试验仪,同时选用纳米及非纳米铝粉样本进行比对分析,实验项目:包括最小点火能量,最大爆炸压力,爆炸最大压力上升速率,最低含氧浓度及爆炸下限。在理论研究和实验研究的基础上,提出了可使用的防治技术,其中包括:1爆炸的预防技术(1)含氧气浓度控制,(2)可燃性物质浓度控制。2.爆炸损失控制技术包括(1)抑爆控制技术,(2)耐爆控制技术,(3)火焰侦测及灭火系统,(4)隔爆控制技术,包括:旋转阀、灭焰器、自动快速反应阀系统,、火焰前端转向器、化学隔爆系统和泄爆控制技术。防治技术可应用于下列场所,1.制造,处置,处理可燃性物质场所,2.在铝粉的制造场所,3.在铝粉的处置(含研磨及抛光)之场所;具体内容从系统的安全设计,设备选用,危害评价及控制,灭火系统,到管理系统安全要求。最后,本论文提出了未来可进一步研究的方向:即,可进一步运用其它灭火剂如二氧化碳或碳酸氢纳或碳酸氢纳钙进行灭火效果研究,可进一步开展针对水份(或湿度)对纳米铝粉安全特性的影响研究,增加对纳米铝粉对非纳米铝粉其它安全特性的研究,及利用原子力妇描探针显微仪来探讨纳米铝粉的结构研究。更多还原

【Abstract】 Nano-structures generally refer to the size of 100 nm.This is because of the nano-materials with small particle size and large surface area,high surface energy,so as to form their specific three major effects: surface effects,small size effect and macroscopic quantum tunneling. National Science Foundation of Unit States estimates around one million million US dollars value of output for related nano–production in global market by the year 2015 from 2010. However,the Nano is a double-edged sword,problems arise; there are three research groups published a nano-materials report with special toxicity in the annual meeting of the American Chemical Society in 2003. Yet no study of the safety characteristics on nano-explosion has been conducted. Both dust explosion and fire prevention in industrial enterprises are critical issues. China has yearly experienced many dust explosion specialized in aluminum dust explosion , which is belong to the catastrophic accidents. It is worth further investigation because aluminum powder bears the properties of powder dust and fire explosive as well. Both particle size distribution and the shape of a particle surface are the most important factors to contribute the fire or explosion. Nano-technology is the latest technology and developing industry.So,it’s very dangerous to develop a technology without understanding of their characteristics. Industry development will be affected and limited by an accident. We can not develop any control measures for explosion without understanding the safety characteristics of material which includes: MIE (minimum ignited energy),LEL (lower explosion limit),Pmax (maximum explosion pressure),dP/dt (maximum rate of pressure rise) and LOC (limiting oxygen concentration). This paper is a preventive measures and supporting concept and application of safety which is the foundation of industrial development.Literature including coal dust and gas explosion , gas explosion , the characteristics of chemical kinetics during process of combustion,the mechanization of propagation of gas (flammable gases) explosion , research on numerical simulation of the explosion,aluminum powder explosion,experimental methods,control measures of preventive measures and loss control for fire and explosion have been reviewed; but there is no safety research on any naon- aluminum powder.Both theoretical and experimental methods are employed to conduct this study. Theoretical approach to the basic combustion and explosion,the mechanization of combustion and explosion on combustible gas and solid are processed .In addition,topic on conbustion of carbon is covered. Especially,the mechanization of combustion and explosion on aluminum powder is proposed. In experimental approaching a 20- l sphere apparatus is used as the major testing equipment. Samples include 35,75,80 and 100nm of aluminum powder have been selected. Additionally,a non-nano dimension“100μm”of aluminum powder also is tested for contrast between nano and non-nano.The explosion indices include MIE (minimum ignited energy),LEL (lower explosion limit),Pmax (maximum explosion pressure); dP/dt (maximum rate of pressure rise) and LOC (limiting oxygen concentration) are measured.These technologies of prevention or loss control for fire and explosion which include oxygen concentration reduction,combustible concentration reduction,Deflagration Suppression , Pressure Containment , Spark Detection and Extinguishing Systems,Isolation Systems which will cover Rotary Valves,Flame Arresters,Automatic Fast-Acting Valve Systems,Flame Front Diverters,Chemical Isolation System and Venting of Deflagration can be referred and used. The application from system design to safety management system for these technologies of prevention or loss control for fire and explosion can be to facilities where are the manufacturing or processing and handling of combustible particulate solids,manufacture of Aluminum powder and processing and finishing of Aluminum. In the future,we may consider further investigation on other extinguishing agents like carbon dioxide or sodium hydroxide or calcium hydroxide and their performance on nano Aluminum powder,the influence of moisture on nano Aluminum,other studying on safety characteristics between nano and non-nano Aluminum powder,and the structure of nano Aluminum powder by atomic force microscope.更多还原