【作者】 罗自学；

【导师】 周怀春；

【作者基本信息】 华中科技大学 ， 热能工程， 2007， 博士

【摘要】 火电厂炉内燃烧检测的手段和方法,受制于炉内强烈的燃烧行为。由于无法克服的传统热量信号对燃料扰动的滞后,采用新的控制理论和先进算法,来尝试提高机组负荷控制及燃烧优化控制的品质,效果并不明显。利用数字图像处理技术,通过对火焰图像的深度挖掘,从炉膛燃烧的火焰图像中提取辐射能信号作为中间桥梁,利用辐射能信号快速反映炉内燃烧工况的特性,把燃烧率和风煤比关联起来,将其引入到机组负荷控制和燃烧优化控制回路,是一种全新的策略。本文分析了炉内燃烧监测及燃烧优化控制的现状,以燃烧火焰图像为出发点,全面分析了辐射能信号的应用进展,依据炉膛辐射能信号的检测原理,独立设计了300MW火电机组炉内燃烧图像的实时检测系统,并对其硬件配置及软件进行了分解设计。提出了基于多测点、三维空间辐射图像的炉膛辐射能信号检测方法,得到了12只火焰图像探测器依不同加权和所提取的辐射能信号,并从原理上对其提取机理进行了分析,与传统热量信号进行了比较。在定量描述辐射能信号在机组热力系统的关联作用的基础上,从热力过程的动态特性出发,通过炉内的辐射能表征,探讨了辐射能信号在热力过程中的变化规律,通过对燃料量扰动、二次风量和摆角等一系列实验,获得了炉膛辐射能信号的动态变化特性,得到炉内的辐射传热、烟气侧对流换热与炉膛燃烧强度的关系,并以此进行了仿真,证明了辐射能信号引入到机组控制的可行性。针对传统的机炉协调控制的缺陷,提出将辐射能信号引入到机组负荷控制的策略,将辐射能信号引入到协调炉侧的调节系统中参与燃料控制的内回路过程调节,使燃料量主令信号提前响应燃烧扰动,提高了机组负荷和主蒸汽压力调节的品质。在分析炉膛辐射能信号与风煤比关联作用的基础上,在锅炉送风自动调节系统中,设计并投入以辐射能为寻优目标的锅炉氧量寻优控制。在给煤率保持稳定的工况下,启动锅炉燃烧配风自寻优功能,以辐射能信号最大为目标,自动寻找最佳的燃烧配风量,机组整体效率提高了1%,NOx排放平均减少12%以上,具有良好的经济效益和环保价值。引入辐射能信号到DCS相关控制回路的设想,是对传统机炉协调控制及锅炉燃烧优化控制在概念上的拓展。通过本文的研究,有效地解决了从炉侧热量信号到机侧实发功率控制响应中的“快-慢-快”向“快-快”转移的技术难题,对于燃烧及相关回路的优化调节,提供了一个非常有效的手段。更多还原

【Abstract】 Test method of combustion is strongly restricted by combustion behavior in coal-fired power plant boiler furnace. It is not obvious to improve the quality of load and combustion control at adopting new control theories and advanced algorithm, due to the lag of traditional caloric signal with the disturbance of coal quality or quantity. By digital image processing technique and deep excavation of flame image, obtained principle of Radiant Energy Signal(RES or E) is put forward. This is a new control strategy at inducing E into load and oxygen control circuit, which E gotten from combustion flame images is as a bridge.In this paper, present condition of boiler combustion monitoring and its optimizing control is analyzed. A set of flame image monitoring system in a 300MW coal-fired power plant has been designed according to the synthetic method of reference thermometric in boiler furnace. Hardware and software of the system are also designed at that time.The comparison between E and traditional caloric value signal is carried out. According to the principle and characteristic of synthetic method, a kind of monitoring method about E is put forward based on multipoint and three-dimensional flame images, which is obtained from a dozen of CCD cameras by weighted sum of different installed position and their parameter settings.On the basis of quantitative described correlation of E in thermodynamic system, the change regularity of E is researched, with the regulating capacity of the disturbance of total coal, secondary air register and tilt angle. At the same time, the dynamic characteristic of E is gotten, among the relationship of E with heat transfer in furnace and heat convection in flue gas. It is feasible to introduce E into load control circuit in simulation study.A new coordinate control model on inducing E, where it is against the defect of traditional coordinated control system, is put forward as a command signal, due to the fact that the burning rate may be rapidly responded combustion in furnace. This new control strategy in inner circuit of fuel, by using RES, instead of calorific value signal and pressure signal, is useful for increasing the dynamic characteristics of stabilization of load and pressure.Traditional combustion control strategy has been meliorated by inducing radiant energy signal(E) into oxygen control circuit on the basis of analyzing the association between E and air/coal ratio. Through modification and in-situ operation, the control property under the optimized air/coal ratio can always hold the E in high-level and response combustion condition correctly. The new industrial scheme is proved to improve the efficiency of unit about 1%, reduced discharge of pollution (NOx) above 12%. It is an ideal concept for economy and environmental protection.It is a stretch in concept to traditional coordinated control system at introducing RES into duct pilot in this paper. Through the research of this paper, the technical puzzle from“fast-slow-fast”to“fast-fast”, which is more quick response to the disturbance of fuel as opposite to caloric value signal, has been resolved. It provides an available method of optimized combustion accommodation implemented here.更多还原