【作者】 秦健伟；

【导师】 周怀春； 罗自学；

【作者基本信息】 华中科技大学 ， 热能工程， 2011， 硕士

【摘要】 船用增压锅炉炉膛火焰的脉动对于汽包水位有着重大的影响,炉膛火焰的在线监测对于稳定汽包水位有着重要的意义。本文在总结船用增压锅炉结构和工作特点的基础上,介绍了安装于某船用增压锅炉上的炉膛火焰检测系统;对试验中采集的图像进行了分析和讨论,提出了由火焰图像处理技术计算船用增压锅炉炉膛辐射能信号的方法;对辐射能信号的分析表明,船用增压锅炉的工作特性造成了炉膛内火焰的剧烈脉动,这使得锅炉蒸发系统内上升管的吸热量随之脉动,造成了汽包水位的大幅波动。结合船用增压锅炉对流蒸发管束的构造和烟气流动特性,对蒸发系统内的换热进行了细致的研究;本文将水冷壁和对流蒸发管束合在一起,作为上升管,认为上升管吸热量由炉膛总换热量和炉膛外对流蒸发管束的吸热量组成;传统的热力计算方法无法反映实时的上升管吸热量,本文得出了辐射能信号与上升管吸热量间的对应关系,并将由辐射能信号计算得到的上升管吸热量引入了蒸发系统动态数学模型中,这样,由此模型得到的汽水系统的动态特性便能够反映炉膛内火焰的实时燃烧情况。使用Fortran语言编写了仿真程序,由于采用了建立数据表进行插值计算的方法,程序的计算速度很快。进行了仿真试验,对得到的响应特性曲线进行了深入分析;本文发现,阶跃扰动后汽包内液面下汽和水体积的变化方向不同,汽和水体积变化的综合作用造成了“虚假水位”现象。给出了上升管吸热量(炉膛辐射能信号)脉动对汽包水位影响的仿真结果,上升管吸热量的波动造成了汽包水位的大幅扰动,通过监测炉膛辐射能信号对汽包水位进行超前的控制有巨大的应用潜力。更多还原

【Abstract】 The pulse of flame in the furnace of marine supercharged boiler will affect drum water level significantly, therefore, real-time detection of flame is very important to stabilize drum water level.This paper summarizes the structure and working characteristics of a marine supercharged boiler, based on that, describes the furnace flame detect system installed on that boiler. After analyzing and discussing the flame images captured from experiments, a method to calculate Radiative Energy Signal (RES) is proposed. Analyses of RES show that working characteristics of the marine supercharged boiler cause fierce pulse of flame in the furnace, which makes heat absorption rate of riser change frequently with that, and finally leads to a fluctuation of drum water level.Taking structure of convective evaporation tubes and fluxion characteristics of flue gas into consideration, this paper studies the heat transfer in the evaporation system. By combining water wall with convective evaporation tubes, heat absorption rate of riser is obtained from the overall heat absorption rate in the furnace and heat absorption rate of the convective evaporation tubes outside furnace. The traditional thermal calculation can not reflect real-time heat absorption rate of riser, however, after gain relationship between RES and heat absorption rate of riser, this paper introduces heat absorption rate of riser calculated from RES into the dynamic mathematical model of evaporation system, in this way, dynamic characteristics of the steam-water system captured by the model are able to reflect the real-time combustion condition of flame in the furnace.Simulation programs are written with Fortran. Because of the application of interpolation method, simulation programs run quit fast. Respond characteristic curves obtained from simulation experiments are deeply researched. This paper shows that volume of steam and water under water level in the drum change differently after step disturb, and the integrative action causes the“false drum water level”phenomena.Simulation results of drum water level fluctuated by heat absorption rate of riser (RES) are given, analysis shows that pulse of heat absorption rate of riser leads to a significant fluctuation of drum water level. There is a great potential to control drum water level in advance by introducing RES into control system.更多还原