【作者】 聂欣；

【导师】 周俊虎； 曹欣玉； 岑可法；

【作者基本信息】 浙江大学 ， 热能工程， 2007， 博士

【摘要】 电站煤粉锅炉的冷态启动和低负荷稳燃需要消耗大量燃料油。电站锅炉的煤粉直接点火技术是节省燃料油,降低电站运行成本最有效的手段。本文采用中频感应加热热壁面点火和高温空气点火两种方式,对电站锅炉的煤粉直接点火进行了系统的实验研究。在中频加热热壁面点火试验研究中,对煤粉浓度,煤种,燃烧器结构等因素对煤粉着火燃烧的影响进行了的试验研究。并对煤粉管内的热壁面点火进行了数值模拟,对其着火方式进行了探讨。最后,在衢化集团热电厂的130t/h中压锅炉上成功地实现了多级煤粉点火。将化工上用于混合的SV型静态混合器与中频感应加热器相结合,发明了一种新型高温空气加热器。并对其阻力特性,电源特性以及加热效率进行了试验研究,结果表明这种新型高温空气加热器不但可以将冷空气温度加热到900℃以上,而且加热效率高,结构简单,可靠性高。在此基础上,发明了一种新型高温空气点火燃烧器,建立了相关试验系统。并使用神华混煤和充州煤进行了系统试验。首先,进行了工业设计应用为目的的试验。对燃烧器的各个部件的结构尺寸进行了着火热风温度的试验,结合燃用的煤种,从快速点燃和安全运行两方面综合考虑,决定合适的具体结构尺寸。采用不同粒径的神华混煤和兖州煤,对点火热风的着火温度与熄火温度各个影响因素进行了试验研究。对各个不同因素影响下的点火燃烧器内部流场进行了数值模拟,进一步验证和认识了点火燃烧器设计的合理性以及煤粉气流在燃烧器内的着火升温过程。试验与计算结果表明,所设计的点火燃烧器无论是从煤粉的点燃角度,还是从长时间运行的安全性(主要是指预防燃烧器超温和结焦)角度看,都是比较成功的。其次,以研究煤粉在高温空气加热过程中着火机理为目的的试验研究。在煤粉气流形成均相火焰前后两个阶段,不同点火热风温度下,通过煤粉颗粒的孔隙结构、挥发分与煤焦消耗率、煤粉粒径分布以及燃烧器出口烟气成分的测量,对煤粉的行为特性进行了试验研究。试验结果详细揭示了处于高温高速湍流气流中不同粒径煤粉颗粒的着火前后过程。对东北贫瘦煤的高温空气点火进行实验研究。对其在受热着火过程中的孔隙结构、挥发分与煤焦消耗率、烟气成分的变化进行测量,并与烟煤进行比较。提出了一种高温空气多级点火燃烧器,并建立相关试验系统。对影响多级点’火燃烧的各个工况因素进行研究。试验证明,多级点火燃烧器的设计是成功的,基本解决了直接点火燃烧器上结焦的困扰。更多还原

【Abstract】 In power stations, Great mount of diesel oil has been consumed at beginning of boiler running or in low-load period. The technology of direct igniting pulverized coal is the most effective method of saving diesel oil and cost reduction in power stations.The system experiment research of direct igniting pulverized coal have been done by two methods of hot-wall ignition and high temperature air(HTA) ignition, which are heated by medium-frequency introduction-heating.In the research of the hot-wall ignition heated by introduction-heating, the experiments have been done about the influencing of pulverized coal concentration, coal species and combustor structure to pulverized coal ignition and combustion, numerical simulation has been done, and the mode of ignition has been discussed. At last, multi-stage ignition has been realized on the130t/h medium-pressure boiler of a power station.A new style HTA generator has been invented through combination of SV static mixer and introduction heater. The experiments have been done about characteristic of flow-drag and electricity, heating efficient. The result shows the new style HTA generator not only can reach the requirement of the HTA ignition pulverized coal but also have virtues of high efficiency, simple structure, high reliability.Then, a new style HTA ignition combustor has been invented, and its experimental system has been built, and a great mount of experiments have been done. Shenhua blending coal and Yanzhou bituminite have been used.First, on the purpose of industrial design and application, experiments have been done about influencing of physical dimensions on ignition temperature; the physical dimensions have been decided according to the experiment results and coal species. The influencing factors of ignition and flameout HTA temperatures have been experimented by use of different size pulverized coal, and numerical simulation of interior flow field of the HTA ignition combustor has been done. Their results all can show that design of the new style HTA ignition combustors is succeed in way of ignition pulverized coal and safe operation, can prevent the combustor from coking and excess temperature. Second, on the purpose of the mode of pulverized coal ignition and combustion in HTA, fore and after appearance of homogeneous flame, the change of the porosity structure, consumption of volatile and char, particle sizes distribution of pulverized coal and component of flue-gas at the combustor outlet have been measured as the change of the HTA temperature, the results show the most of pulverized coal. The results reveal the process before and after different size pulverized coal being igniting in high temperature and turbulent flowing air.The same experiments have been done on the Dongbei lean coal, the results have been compared with bituminite.The HTA multi-stage ignition combustor has been invented, and its experimental system has been built. The influencing factors of ignition and combustion have been experimented in the combustor, the results show the invention of the HTA multi-stage ignition combustor is succeed.更多还原