【作者】 康志忠；

【导师】 孙保民；

【作者基本信息】 华北电力大学（北京） ， 热能工程， 2009， 博士

【摘要】 节能减排是实现国民经济可持续发展的重要措施,尤其是对于火力发电行业。本文着力于解决当前电站煤粉锅炉从点火启动到满负荷运行过程中与节能和环保密切相关的三大问题,作为国家“863计划”项目《燃煤锅炉超低负荷洁净高效控制与运行技术的研究及应用》的主要研究内容,针对某200MW机组锅炉开发了一套基于高温空气点火,并与水平浓淡燃烧器和立体式空气分级燃烧技术有机结合的成套技术,实现了该锅炉在全负荷范围内的稳定、洁净运行。根据高温空气点火燃烧器的结构特点和点火要求,提出了几种不同的煤粉浓缩器设计方案,并对不同方案下的气固两相流动进行了数值模拟研究,得出了各方案的浓缩效果和阻力特性,为工程应用中浓缩器的选取提供了参考。先后对单级筒点火燃烧器和三级点火燃烧器在不同参数工况下的着火特性进行了数值模拟研究。找到了主要工况参数对着火过程的影响规律,给出了对于特定机组和煤种的最佳参数范围。研究了采用高温空气点火实现200MW机组无油点火启动运行中的关键技术问题,制定了高温空气点火启动方案。对逐个投入四个点火燃烧器这一启动过程进行了炉内燃烧过程数值预报,提出了工业应用中适时切换燃烧器的合理性建议。预报结果表明所制定的启动方案能满足锅炉启动曲线的要求,与工业应用中现场所得启动曲线吻合较好。提出了将高温空气点火燃烧技术与水平浓淡燃烧器联合应用的方案。预报了将其应用于200MW机组锅炉后,30%-50%MCR工况下的炉内燃烧工况。预报表明,这种联合应用技术稳燃效果显著。借助水平浓淡燃烧器的稳燃能力,可将实际运行中停运高温空气加热的负荷点前移,减少了发电成本而且污染物排放降低。应用立体式空气分级燃烧技术思想,将CFS燃烧技术、水平浓淡燃烧技术与垂直方向的整体空气分级联合应用,提出了一套低NO_x燃烧技术改造方案,采用冷模试验和数值模拟相结合的方法,对方案中关键改造参数和运行参数的选取进行了研究。针对特定机组锅炉结构及其煤质提出了全负荷稳定、洁净运行成套技术方案,并形成了系统的研究路线。该技术方案的主要内容在实际机组进行了改造应用,结果表明,超低负荷下排烟的林格曼黑度＜1级,启动和超低负荷时的烟尘排放降低90%以上,低负荷时燃烧稳定且NO_x排放量降低30%左右,经济和环保效益显著。该集成方案在类似机组具有适用性。更多还原

【Abstract】 Energy saving and pollution reducing are important measures to achieve sustainable development of the nationfil economy,especially for power industry.This article focuses on resolving three major issues of current pulverized coal fired boilers in power stations from ignition of start-up to 100%MCR load,which are closely related to energy saving and environmental protection.As the main research of the project,the study is financed by National ’863 Program’(The National High Technology Research and Development Program of China) project(No.2003AA529280):’The Research and Application of Operation Technology to Clean and Efficiently Control the Coal-fired Boiler on the Ultra-low Load’.The assembled technology for a 200MW utility boiler was developed to realize the stable and clean operation in the whole range of the boiler’s load,it is based on the ignition technology of high temperature air,and is organically combined with the other two technologies,one is of horizontal bias burner,the other is three dimensional air staged combustion technology.According to the structural characteristics of the high-temperature air ignition burner and its ignition requirement,several different designs of concentrators were proposed.Numeric studies were done to simulate the gas solid two phase flow under the different schemes.This research provided a reference to the selection of the schems in the subsequent engineering applications.The numeric simulations were done to study the ignition characteristics of a single-stage ignition burner and three-stage ignition burner under conditions of different parameters,and thus find the laws of how the main parameters influence the ignition process.The ranges of the optimal parameters were given for specific utility boiler and quality of its fired coal.Key technical problems were discussed related to the 200MW utility boiler started up by the oil-free ignition of high temperature air.The start-up scheme was programmed.Numeric predictions of the combustion process in the furnace were carried out to study the start-up processes when the four ignition burners were put into operation one by one.It is proposed that the burners should be switched timely during the start-up in industrial applications.The prediction results showed that the start-up scheme could meet the requirements of the start-up curve of boiler.The results agreed well with the curve getting from the industrial application.A retrofit scheme applied for stabilizing the combustion was put forward,which combined high temperature air ignition burner with horizontal bias burner.Numeric predictions of the combustion process in the furnace were done under 30%-50%MCR conditions when the combined scheme was applied to 200MW utility boiler.Forecasts showed that the stable effect of the combined combustion technology is significant.By means of the stable ability of horizontal bias burner,the load point under which the high temperature air heater could be halted was put forward during the actual operation,reducing the cost of power generation and the pollutant emissions.The three dimensional air staged combustion technology was applied to the utility boiler,which combined the Concentric Firing System(CFS),horizontal bias combustion and the air-staged combustion alone vertical direction of whole furnace.On the base,a set of retrofit scheme was proposed to reduce the NO_x emissions.The method combined cold model experiment with numeric simulation was adopted to study the selection of the key retrofit parameters and operation parameters in the scheme.The assembled technology scheme was carried out for specific structure utility boiler and quality of its fired coal,and the systematic research route was formed.The main contents of the technical program had a retrofit application to the actual utility boiler. The results showed that the Ringelmann blackness of flue-gas is less than one class under the ultra-low load.The retrofit reduced soot emission by 90%during the start-up, and the combustion was stable,30%NO_x emission was reduced under the low load.The assembled technology has significant economic and environmental benefits,and has applicability in similar units.更多还原