【作者】 罗玉萍；

【导师】 王立久；

【作者基本信息】 大连理工大学 ， 材料学， 2008， 博士

【摘要】 资源与环境问题是密切相关的可持续发展的两大基本问题。本文用材料过程工程学的研究方法,以调查研究和科学试验为手段,以煤电转化过程为研究对象,以煤电转化过程各环节(子过程)“资源减量化、产品再利用、废弃物资源化”为原则,以资源节约和循环利用为核心,以低消耗、低排放、高效率为基本特征,对这一过程进行优化与集成,并对过程排放的污染物进行环境影响的分析评价,使优化的过程符合资源综合利用的要求,节约能源的要求,清洁生产的要求,可持续发展的要求,符合建立在生态学规律之上的循环经济的要求。目的是在工业区或区域层面发展生态工业,把上游生产过程的副产品或废物用作下游生产过程的原料,形成企业间的工业代谢和共生关系。在过程工程学的基础上,对材料过程工程学的框架体系进行了研究。以煤电工业和水泥工业间的交集—废渣的资源化过程的研究为例,进行煤电转化过程的优化与集成。要实现联产首先要优化煤电转化过程。对煤电转化过程各子过程包括动力煤洗选及配煤过程、燃煤发电过程、煤系固体废物综合利用过程、脱硫脱硝过程等的发展现状进行分析研究,分析各子过程存在的问题,提出了技术上及政策上解决的策略。由联产技术得到的联产灰,采用水泥性质实验、化学分析、XRD分析及SEM分析,对煤粉炉和循环流化床锅炉排出的两种粉煤灰(PF灰和AFBC灰)的性质进行对比分析研究,结果表明,化学成分差异不大的两种灰,PF灰细度大、晶相含量小、活性大、强度贡献大、需水性小;PF灰颗粒细小,球形颗粒相对较多,颗粒表面相对较光滑;AFBC灰颗粒相对较粗大,不规则颗粒较多,表面较粗糙,且孔洞较多。通过优化燃煤过程和联产技术,提出了一种新的粉煤灰的科学分类方法,将粉煤灰按发电方式及含钙量分为高钙PF灰、低钙PF灰、高钙AFBC灰和低钙AFBC灰,更有利于粉煤灰在建筑工程和建材工业方面的分类利用。本联产技术是基于煤粉炉燃煤与硅酸盐水泥熟料生产具有相近的温度条件,粉煤灰与水泥熟料具有相似的化学组成。把煤粉炉视为煤粉成分的反应器,进行了煤粉掺杂在与煤粉炉燃煤相似的燃烧条件下的试验研究,通过XRD图分析可以看出,随着含钙量的增加,煤粉灰中的莫来石逐渐消失,形成了钙铝黄长石,随着含钙量的进一步增加,钙铝黄长石的含量又逐渐减少,形成了新的水硬性的硅酸二钙。结果表明,煤粉掺杂量在一定的范围内,经高温快速燃烧可以生成具有水硬性的贝利特矿物,燃煤发电联产水泥是可行的。初步进行了联产灰的性质及利用研究。分析了燃煤发电联产水泥研究现状,找出其存在的问题,认为燃煤发电联产水泥技术的研发是一项系统工程,必须结合我国火电技术的发展,组织相关学科专家、学者联合攻关才能完成。提出燃煤发电联产水泥技术的研究思路,即顺应煤种、炉型和炉膛温度等条件,研究锅炉燃烧状况下,煤-渣变化的规律,在此基础上,研究煤粉的配方,经安全发电后获得不同水硬性成分的熟料。利用(?)分析原理,分析计算煤电转化过程的(?)效率;利用煤电转化过程排放物的(?)值,分析计算煤电转化过程排放物对环境的影响。用环境负效应数学式结合气载流出物的非致癌污染物健康危害数学式,参照我国《环境空气质量标准》及《火电厂大气污染排放物标准》评价煤电转化过程对环境及人体健康的影响。对我国燃煤发电技术发展进行了分析研究,认为我国未来几十年主流发电方式是最有技术继承性、最具条件在短时间内实现规模化生产、最具优化火电结构等优势的超(超)临界发电,以及环保效果较好的循环流化床锅炉发电。以这两种发电方式为核心,对整个煤电转化过程进行优化与集成,提出符合我国实际的煤电转化过程路线,并提出优化集成的煤电转化过程及煤系主要产物循环利用途径。更多还原

【Abstract】 Both available resources and environment are the two essential issues that are closely related to the sustainable development. In this paper, the process of converting coal into electricity is optimized and integrated by employing the methodology of material process engineering, together with scientific survey and experiments. In the study, all the sub-processes involved in the process of converting coal into electricity are taken into account, under the principles of resource minimization, reuses of product wastes and resources, while the resource conservation and recycling are taken as the core value, leading to low consumption, low discharges, and high efficiency. The impact on environment by pollutants is analyzed and evaluated, in order to conform to the requirements of a comprehensive utilization of resources, energy conservation, clean production, and sustainable development, meeting the need of establishing an ecological, environmental friendly and sustainable economy. It is aimed at developing an ecological industry in the industrial region or level, by taking products and in particular the wastes from the upstream production process as the raw materials for the downstream production process, establishing an industrial metabolism and co-existence relationship.The material process engineering’s frame system has be studed on the basis of the process engineering. Intersection between power industry and cement industry- residue of resources is exemplified,and the process of converting coal into electricity is optimized and integrated .Each sub-process involved in the process of converting coal into electricity is analyzed and investigated, including coal selection and blending, coal-fired power generation, comprehensive utilization of the solid wastes by coal formation, desulphurization and denitration. While the problems in each of these sub- processes are revealed, the strategies for solving them by applying new technologies and policies are suggested.The behavior and properties of fly ash produced in the pulverized coal stove （PFA） and circulation fluid bed boiler （AFBCA） have been analyzed and compared, by using the cement experimental method, chemical, XRD and SEM analyses. There is no obvious difference in chemical composition between PFA and AFBCA. PFA exhibits finer particles, a relatively smaller proportion of mineral contents, larger activeness, larger strength contribution and a smaller water requirement as compared to AFBCA. It also consists of smaller spherical particles and smoother surface. In contrast, AFBCA is associated with larger and coarser particles with porous surface.A new classification system for fly ash is proposed in this study, namely the high calcium PFA, the low calcium PFA, the high calcium AFBCA and the low calcium AFBCA, according to the ways of electricity generation and the calcium proportion. The new classification system will benefit their uses and applications in building engineering and building materials industry.Coal burning in pulverized coal fired boilers and calcination of Portland cement clinker are similar in temperature conditions, while the fly ash and cement clinker have similar chemical compositions. Taking pulverized coal fired boiler as a reactor, compound coal is burnt under combustion condition similar to that of the pulverized coal stove. On the basis of XRD phase analysis, one can conclude that with the increase in calcium content, the amount of 3Al₂O₃·2SiO₂ in coal ash gradually disappears, replaced by 2CaO·Al₂O₃·2SiO₂. With further increase in the calcium content, the 2CaO·Al₂O₃·2SiO₂ content also gradually decreases, giving rise to the belite minerals. The experimental results show that in the certain doping range of the powdered coal, the rapid combustion at high temperature generates belite minerals, suggesting that the feasibility of joint production of coal-burning electricity generation and manufacture of cement. Preliminary experimental study has been done on the property and utilization of cogeneration ash.On the basis of the current status of study on the technology of joint production of the coal-burning electricity generation and cement manufacture, some of the key existing problems have been identified. Indeed, the feasible joint production of coal-burning electricity generation and cement manufacture is a system engineering. It is necessary to integrate with the development of thermal power technology, and to organize experts and scholars from related disciplines and joint efforts in order to complete this project. The idea of the integrated production of coal-burning electricity and cement manufacture has to comply with the types of coal and furnace, the temperatures involved and other conditions, where the behavior of coal-slag changes under the boiler combustion condition has to be studied, in order to select the appropriate coal composition and to obtain the clinker of different hydraulicity ingredients safely. The exergy efficiency of two different processes of converting coal into electricity is analyzed and determined according the exergy balance principle. From the exergy of pollutants emitted, the environmental impact of converting coal into electricity is analyzed and determined. The impacts on environment and human health are also evaluated by considering the environmental negative effects, on the basis of the mathematical model combining non-carcinogenic pollutant health hazards and airborne effluents, with reference to the "ambient air quality standards" and "power plant air pollution emission standards".Having studied the technological development of generating electricity by coal-burning in our country, it is concluded that the main electricity generation techniques will be the super （super） critical technology for power generation which is better in technology inheritance, scale-up in short time, optimization in thermal power structure, and the CFB boiler power generation technology which has better environmental results. By taking the two electricity generation techniques as the centre of development, the entire process of converting coal into electricity will be optimized and integrated, leading to the realistic joint process of converting coal into electricity and the comprehensive utilization of the solid wastes.更多还原