【作者】 吴阿峰；

【导师】 李明伟；

【作者基本信息】 重庆大学 ， 工程热物理， 2006， 硕士

【摘要】 本文主要针对四角切圆燃煤锅炉进行了研究。四角切圆锅炉在电站锅炉应用较为广泛,在我国占电站锅炉总容量的80%以上,尽管其NOx单位生成量较少,但其NOx排放量对电站锅炉的NOx总排放量影响较大,而且目前的环保要求日益严格,故必须控制NOx的排放。脱硝技术种类繁多,也各有优劣,效果相对明显的是烟气脱硝技术。由于烟气脱硝设备的投资额大,故选择一种经济有效的脱硝技术就显得格外重要。基于此,本文从宏观上对降低NOx排放的措施进行了比较研究。着重就SCR(选择性催化还原技术)、SNCR(选择性非催化还原技术)以及SNCR/SCR联合技术等三种技术进行了分析,并引进了对电厂投资脱硝设备决策有重要意义的技术经济分析方法。技术分析方面,主要考虑三种脱硝技术的设计参数及对电厂现有设备运行的影响;经济方面,针对两个工程实例,通过计算年费用、脱除每吨NOx的费用以及排污费、贷款政策对脱硝费用的影响等来进行纵横比较。将经济学的动态分析模型用于对烟气脱硝装置的经济评价,为电厂进行初步决策和可行性研究提供了重要依据。深入研究NOx的生成机理,对于降低NOx污染的意义更为重大。过去对于NOx生成的研究主要基于电厂锅炉运行所积累的经验和一些小的试验锅炉所测得的数据,但由于煤粉气流燃烧过程的复杂性和测试技术的限制,这些经验和数据在很大程度上具有局限性。并且试验研究要消耗大量的人力、物力、财力,周期也较长。随着计算机技术的发展,数值模拟由于具有时效性、经济性,得到的数据也非常全面,逐渐成为对燃烧及污染物生成进行研究的重要手段。本文以三菱公司生产的MB-FRR型锅炉(最大连续蒸发量为2290t/h)为研究对象,结合目前已有的NOx生成机理的理论基础,选择合适的数学模型,在对燃烧正确模拟的基础上,对六种不同工况下NOx在炉膛各处的浓度分布情况进行了数值模拟,并单独模拟了热力NOx的生成情况。集中讨论了温度、O2浓度、空气过量系数和一次风率对NOx分布的影响。所得结论与锅炉的实际运行结果基本一致,这对于进一步研究NOx的生成机理和引导NOx低排技术的发展具有指导意义。更多还原

【Abstract】 This article focuses on the tangentially fired boiler. Tangentially fired boiler plays a very important part in the power plant, which occupies more than 80% of the capability of all the boilers in power plant. Therefore, although its unit formation of NOx is less, it contributes more to all the NOx’s drainage. Especially as the restrict of the environment protecting is being stricter, it’s very urgent for us to control its NOx drainage.Among kinds of de-NOx technologies, flue gas de-NOx technology is regarded to have the better effect. To select an economic and effective technology earns especial emphasis by reason of its great investment. Basing on this, the article studies the de-NOx technologies from the macroscopical aspect. All the work of the paper fix attention on SCR, SNCR and SCR/SNCR. In addition, it also introduces a kind of techno-economic method which is of great signification for the decision-making of power plants to invest in de-NOx equipments. Mostly, for the technological analysis, the designed parameters of the three and their impacts on the operation of existing equipment in power plants are taken into consideration; For the economical analysis, aiming at two power plant, compare through calculating the annual fee, unit charge for de-NOx, as well as the effect of charges for disposing pollutants and loan policy on de-NOx expense. The application of dynamic model of economics in the economical evaluation of de-NOx equipment, can surely provide important reference for the preliminary dicision-making and feasibility study of power plants.Lucubrating the mechanism of NOx formation contributes more to the debasement of NOx drainage. In past, the work mainly bases on the experience of the boiler in power plant and the measured data about some small boilers built for experiment, but all these have great localization because of the complexity of the airflow of pulverized coal and the restriction of the measure technology. Furthermore, the study through experiment needs more manpower, material and financial recourses, as well as longer period. Along with the development of computer, numerical simulation becomes a very important means to study the combustion and contamination’s formation, due to its time saving, lower cost and integrated data.Adopting the MB-FRR boiler produced by Mitsubishi as the study object, the paper simulated the distribution of NOx under six different conditions relatively after considering the NOx formation mechanism and appropriate mathematical models.更多还原