【作者】 朱予东；

【导师】 阎维平；

【作者基本信息】 华北电力大学（河北） ， 热能工程， 2008， 博士

【摘要】 摘要燃煤锅炉运行过程中,各受热面不可避免地存在不同程度的结渣和积灰现象。运行中对受热面进行吹灰可以避免严重的积灰或结渣。目前,国内各电站锅炉的吹灰系统大多仍是按事先设定的吹灰周期工作。这种定时定量的吹灰方式常常造成吹灰不足或过于频繁。因此,在锅炉运行中,应尽可能准确地监测炉内结渣积灰的程度和发展趋势,并根据积灰结渣的状况和运行需要,合理、有效地动作吹灰器,及时吹灰清渣。本文针对锅炉炉膛水冷壁结渣对运行参数的影响规律和炉膛结渣在线监测,不同工况下对流受热面的污染在线监测,对流受热面不可逆能量损失的变化规律,吹灰优化模型的建立,吹灰模式的制定,以及吹灰优化系统软件的开发应用等问题作了深入系统的理论、试验研究与大型电站锅炉的工程实践。主要包括以下内容:1.基于数值模拟方法的炉膛污染监测研究1)针对燃煤锅炉炉膛不同区域结渣问题,进行了炉膛结渣数值模拟的研究,获得炉膛洁净状态和结渣状态下的炉膛出口烟气温度分布,并通过热力计算得到屏式过热器出口参数,分析得出了炉膛不同部位结渣时屏式过热器可监测参数的变化规律。2)引入模糊模式识别方法,借助炉膛结渣数值模拟的结果,建立了基于数值模拟的炉膛污染监测模式识别模型,初步实现了对炉膛不同区域结渣的在线监测。2.变负荷工况下对流受热面污染监测的研究与实现通过分析负荷变化对污染监测的影响,建立了对流受热面污染监测动态模型,克服了静态模型在快速变负荷工况下监测结果与实际情况存在偏差的缺点,实现了各种负荷工况下的对流受热面污染在线监测。3.基于熵产分析的吹灰优化理论与实验研究1)对电厂燃煤锅炉运行中对流受热面产生的不可逆能量损失进行研究,得到了对流受热面各种熵产的计算模型,定义了受热面总熵产和熵产数,对不同受热面吹灰前后的熵产变化规律进行分析。2)在受热面熵产分析的基础上,提出了受热面吹灰收益的计算公式和最佳吹灰频率、临界熵产数、以及临界污染率的确定方法,从而建立了基于受热面熵产分析的吹灰优化模型。从保证锅炉安全稳定运行和实现吹灰收益最大化的角度出发,提出了制定吹灰模式的基本原则,建立了四种优化吹灰模式。3)开发了锅炉受热面污染监测及优化吹灰系统。系统具备在线运行监测、优化吹灰指导等功能。在某328.5MW机组的运行实践表明:吹灰优化系统能够及时并比较准确地给出合理的吹灰模式,有效地指导现场的吹灰操作。更多还原

【Abstract】 For coal-fired utility boiler, slagging and ash fouling on heating surfaces are usually inevitable. Heavy slagging and ash fouling can be avoided by sootblowing during the operation. Presently, sootblowing systems of domestic utility boilers are mostly operated on fixed sootblowing period. However, insufficient or too much sootblowing frequently occur under this mode. Therefore, during boiler running, the state and developing trend of slagging and ash fouling should be monitored as accurately as possible, and the sootblower should be operated according to the monitoring results and operation demand to make sure the ash and slagging can be removed effectively and in time.In this thesis, systematically theoretic and experimental studies have been carried out on following problems: the influence of furnace slagging on steam parameters, online monitoring of furnace slagging, online monitoring of convective heating surface fouling under different loads, irreversible energy loss of convective heating surfaces, the establishment of sootblowing optimization model, the determination of sootblowing modes, and the development and application of sootblowing optimization system. Finally, the system was put into practice on several large utility boilers. The main contents are as following:1. Study of furnace slagging monitoring based on numerical simulation1)Numerical simulations of slagging on furnace were carried out, the flue gas temperature distributions of furnace outlet under different slagging conditions and slagging distributions on the water wall of different boilers were determined. The outlet steam conditions of platen superheater were got by thermal calculation, the influence of the furnace slagging conditions and slagging distributions on the water wall on the available steam parameters of platen superheater was analyzed.2)Based on simulation results, fuzzy mode diagnose technology was used, and the diagnose model of furnace slagging conditions was established, online slagging conditions monitoring and diagnose of slagging distributions on the water wall were realized.2. Study and realization of convective heating surface fouling monitoring under different loadsIn order to decrease the difference between monitoring result of static model and practical result under high load changing rate conditions, the dynamic model for convective heating surface fouling monitoring was established according to the analysis of the influence of load on fouling monitoring. The accurate online monitoring of convective heating surface fouling under any load condition was realized. 3. Theoretical and experimental study on sootblowing optimization based on entropy generation analysis1)Irreversible energy losses of convective heating surfaces during coal-fired boiler operation in power plants were studied, calculation models for different entropy generations of convective heating surface were obtained. Total entropy generation and entropy generation index were defined, and entropy generations of different heating surfaces before and after sootblowing were analyzed.2)Based on the analysis of heating surface entropy generation, the equations for calculating maximal sootblowing income of different heating surfaces were proposed, the calculation methods of optimal sootblowing frequency, critical entropy generation index, and critical fouling rate were put forward, which leads to the establishment of sootblowing optimization model based on heating surface entropy generation analysis. Furthermore, principles for determining sootblowing modes were put forward, and four sootblowing optimization modes were built to guarantee the safety, stability and maximum sootblowing income of boiler operation.3)Boiler heating surface fouling monitoring and sootblowing optimization system was developed. The system is of the functions including online operation monitoring, sootblowing guiding and et al. The practical operation on a 328.5MW unit proved that: the proper sootblowing mode can be accurately proposed in time, and the sootblowing can be effectively guided by sootblowing system.更多还原