【作者】 祝红梅；

【导师】 严建华； 蒋旭光； 池涌；

【作者基本信息】 浙江大学 ， 工程热物理， 2009， 博士

【摘要】 随着我国经济的发展,医疗废物的产生量逐年增加。因医疗废物含有大量的细菌和病毒,具有传染性,以焚烧法为代表的热化学处理技术已成为我国处理医疗废物的首选方法,而回转窑所具有的广泛物料适应性,使其成为我国医疗废物处理规划中的主要焚烧炉型。依托国家863计划重点项目(2007AA061302)和浙江省重大科技专项(2007C13084),本文开展了医疗废物热解焚烧特性和回转窑系统内的的运动和焚烧炉内流场的基础研究。本文主要内容包括三部分：对医疗废物的热解焚烧开展基础特性研究；对医疗废物在回转窑焚烧系统内的运动和流场进行分析；并在处理医疗废物的回转式流化冷渣三段焚烧系统进行试验研究,为现有的医疗废物热处置研究提供有益的补充,并为优化回转窑焚烧系统提供帮助。(1)、医疗废物的热解焚烧特性：采用化学热力学平衡模拟和热重-红外联用实验分析手段对医疗废物中的三大类型七种组分进行热解焚烧特性的研究。采用化学热力学平衡模拟得到不同医疗废物组分在热解、气化和焚烧工况下的产物及变化趋势。对医疗废物中的Cl、N和S可能产生的污染性气体进行分析,得到当医疗废物中氯的质量比小于0.1%时,即使不使用脱氯方法亦可使HCl的排放达到国家标准,而高氯质量比的医疗废物在低温焚烧时,还有Cl2单质产生。与此同时,N和S所产生的污染性气体的问题远不如Cl产生的HCl问题显著。通过热重-红外联用实验分析手段,得到医疗废物各组分在热解和焚烧工况下,各析出产物随温度的变化趋势。其中纤维类组分的热解气体在520℃前全部析出,热解气组成复杂,主要有CO2、CO、H20、酸类如乙酸,醛类,酮类和烃类物质。高分子类组分的热解气在约570℃的前全部析出,其热解气的组成种类较为单一,除了PVC的热解中析出HCl,其它主要为烃类,包括不饱和烯烃和饱和烷烃。易腐有机质的热解气全部析出所需要的温度为614℃,热解气主要由NH3、HCN、酸类、CO2、CH4和饱和烃类组成。在混合组分的热解中,PVC的加入对纤维类各组分和易腐有机质组分的热解产生较大影响。一方面通过热力学平衡分析可知,当医疗废物中氯质量比大于0.1%时,HCl的排放就可能超出国家标准,另一方面,在医疗废物的焚烧过程中,HCl造成的酸性气体腐蚀和不能达标问题较为严重。在医疗废物热解焚烧基础特性部分,亦对高含氯量的PVC和模拟医疗废物的HCl排放及脱氯效果进行了随温度的连续分布研究。通过对各组分的热重结果进行分析,得到各组分整体反应表观动力学模型中的机理函数,而对各组分的热解气的析出进行分析,得到各组分析出产物的分布式活化能模型。(2)、叙述了料床在回转窑内的运动模式和以壁面摩擦系数、填充料和Froude数表达的模式变化判断标准,通过拟流体模型,研究了回转窑转速和：颗粒摩擦角对料床的活动层的倾角、活动层高度和颗粒运动速度的影响。随着转速的提高和颗粒摩擦角的增加,料床活动层高度呈增加的趋势,料床活动层的倾斜角和活动层的面积增加,随着转速的提高,活动层内颗粒的运动速度增加,且在料床活动层的表面,颗粒有最大的运动速度。通过商用软件Fluent,综合考虑了k-ε双方程模型,P1辐射模型,气相的漩涡破碎模型／有限化学反应模型,并通过UDF增加对固定碳燃烧的考虑,对回转窑系统的焚烧流场进行分析,得到整个系统中温度最高的区域可能出现在窑和二燃室的接口位置,而窑头的漏风对窑内的温度和组分场有较大影响,对于二燃室内的燃烧,二次风的影响远大于三次风的影响,通过额定工况的计算和变工况的对比,得到窑内配风和二燃室配风的最佳结合,以及变工况对系统出口温度和烟气组成的影响。(3)、介绍了由浙江大学热能所开发的危险废物回转式流化冷渣三段焚烧炉系统,通过该系统的试验研究,得到了医疗废物焚烧时的烟气成份,灰渣成份,重金属和污染物排放等基础特性,并对焚烧装置运行中的控制参数之间,对烟气排放的影响进行相关性分析,表明温度依然是医疗废物焚烧中,影响整个系统运行工况好坏的重要参数。更多还原

【Abstract】 The amount of medical waste(MW) increases as the development of the economy, which contains a great quantity of bacteria and viruses. Among current technologies, thermal treatment especially the incineration has been found to be widely used in China. At the same time, rotary kiln is used as an important kind of incinerator due to its flexible feedstock capability.Funded by National High Technology Research and Development Key Program of China(2007AA061302) and Important Project on Science and Technology of Zhejiang Province of China(2007C 13084), the study of pyrolysis and incineration of MW, including numerical simulation of three-stage rotary kiln system, were carried out. Based on the pyrolysis and incineration mechanism of MW(TG-FTIR), numerical simulation on three-stage of rotary kiln system was studied by FLUENT. Finally, a new three-stage rotary kiln incinerator system for MW pyrolysis and incineration was put forward, and experiments on this disposal system were carried out.Experimental investigate of pyrolysis and incineration characteristic of MW is introduced in PartⅠ. Pyrolysis and incineration kinetics also volatile releases of seven typical components of MW were thoroughly studied through complex chemical equilibrium analysis and TG-FTIR system. The products of MW under pyrolysis, gasification and incineration were got by chemical equilibrium analysis. According to the investigation of pollutant product from Cl, N and S, HCl concentration was higher than N and S pollutant, the HCl in the flue gas could meet the need of National standard without scrubber, when less than 0.1% of Cl in MW. At the same time, Cl2 formatted when MW with high Cl composition incinerated at low temperature.The distribution of volatile release of MW was got by TG-FTIR. All volatile from cellulose released before 520℃, including CO2, CO, H2O, acid such as acetic acid, aldehyde such as benzaldehyde, ketone such as 2-butanone, and also hydrocarbon. All volatile from plastic released before 570℃, mainly including hydrocarbon, except HCl released from PVC pyrolysis and incineration. All volatile from tissue released before 620℃, including NH3, HCN, acid, CO2 and hydrocarbon. The kinetic mechanism of seven components of MW was got through TG and distributed activation energy model was set up for volatile release.For the mixture of MW, the effect on PVC to cellulose and tissues was greater than that to plastic. On one hand, from to the chemical equilibrium analysis, HCl in flue gas would exceed the need of National standard when more than 0.1% of Cl in MW. On the other hand, HCl is harmful and corrosive, either directly or indirectly formation highly toxic dioxins and furans in the furnace effluent. Thus, the pyrolysis and incineration of PVC and MW was timely and continuous analyzed, HCl removal efficiency and Ca-based additives were quantitatively studied.Numerical simulation of three-stage rotary kiln system is introduced in Part II. After reviewed the motion of particle in the transverse plane of rotary kiln, including the effect of wall friction, filling ratio and Froude and its functions. The effect of rotate speed, friction angle of wall of the active layer and velocity of particle were studied through Euler-Euler model. From the computation result, the height, slope and area of active layer increased as the increase of rotation speed and friction angle. The particle velocity increased as the increase of rotation speed, and the maximum speed was found at the surface of active layer.A physical-chemical process inside three-stage rotary kiln incinerator was performed with Computational Fluid Dynamics(CFD) code(FLUENT). Standard k-εturbulent model, finite rate/eddy-dissipation reaction model and P1 radiation model were chosen, as well as the char burnout were consider through UDF. From the analysis of the three-stage incinerator, the highest temperature appeared at the connection between rotary kiln and secondary chamber, the effect of leak air from the head of kiln, as well as secondary air and fluidized air to the whole system were analyzed, the fitting arrange of secondary air and the suitable ratio between secondary air and fluidized air were got.Introduce the engineering project of three-stage incinerator system is introduce in PartⅢ, the system was developed by State Key Laboratory of Clean Energy Utilization in Zhejiang University, which linked rotary kiln with secondary chamber. Experiments on this disposal system were carried out, including the characteristic of flue gas, fly ash, bottom ash, heavy metal and dioxin. From the experiment results, we could found that this three-stage incinerator system was suitable for medical waste incineration. According to the analysis of relation among the operation parameters, temperature was the most important parameter to the whole system.更多还原