【作者】 杨卫娟；

【导师】 周俊虎； 曹欣玉； 岑可法；

【作者基本信息】 浙江大学 ， 工程热物理， 2003， 博士

【摘要】 电站燃煤锅炉积灰结渣不仅会降低锅炉效率、影响经济性，而且更是多种安全事故的隐患，而采用吹灰器吹灰是解决这一问题最常用最有效的方法。针对我国电站锅炉吹灰器利用率和利用水平低的现象，以电站锅炉日常吹灰运行为研究对象，理论研究为主，研究受热面灰污监测模型和吹灰器优化运行，探索电站锅炉日常吹灰优化运行的策略方案。 首先探索锅炉变负荷运行时炉膛自然掉渣的机理，创新性地开展锅炉运行条件对炉膛灰渣的影响。针对锅炉变负荷运行时炉膛的自然掉渣现象，分析锅炉水冷壁渣层中热应力的产生机理，建立了水冷壁渣层热应力的计算模型，计算分析了锅炉大范围变负荷运行产生的渣层热应力变化大小和分布，并分析渣层热应力的影响因素。得出锅炉大范围变负荷运行时热应力能够超过渣的强度极限引起渣结构破坏的结论，渣层的热应力主要取决于渣的结构、物理特性和传热状态。进一步分析了北仑1#锅炉水冷壁热应力大小和掉渣作用。得出锅炉降负荷运行有助于除去炉膛内小块灰渣和厚渣块的外部渣层，很难将厚渣块整块除去。锅炉降负荷运行有一定程度清洁炉膛水冷壁作用，能增强炉内传热，却无法防止炉膛内结渣恶化发生严重事故。 在分析研究总结现有的锅炉各类受热面的各种灰污监测技术和模型的基础上，建立了锅炉炉膛、对流受热面和三分仓空预器的灰污在线监测模型，以清洁因子表征受热面灰污对锅炉受热面传热的影响。基于稳态传热的清洁因子灰污监测模型，对锅炉负荷、燃煤品质、过量空气系数、各类工质流量、燃煤量和锅炉热效率等的波动变化有很好的适应性。以北仑电厂1#炉历史库中数据为输入数据，验证了清洁因子模型的正确性和对稳定负荷的适应性。针对对象锅炉受热面和测点布置特征，讨论了各监测模块清洁因子的相关性和对吹灰的敏感性。用数学微分方法理论研究清洁因子灰污监测模型中的误差传递规律，探索主要监测参数误差对清洁因子的影响规律，并加以验证。 在现有吹灰器研究和运行水平的基础上，全面分析电站锅炉各部位受热面灰污对锅炉各方面性能的影响，将电站锅炉吹灰的收益和成本各归纳为五类，得出不同受热面吹灰的收益和成本不尽相同的结论。研究每种成本和收益的精确计算方法，并以北仑发电厂1#锅炉为研究对象，通过计算清洁因子对锅炉性能的影响，以统一标准比较各种吹灰收益和成本的大小。其中最小的收益和成本分别是降低引风机电耗和驱动装置电耗成本，最后得出电站锅炉合理吹灰可以获得数十倍利润。 重新界定电站锅炉吹灰优化运行的内涵和外延，率先研究电站锅炉以单个灰污监测模块为优化单元的多目标吹灰优化问题。结合当前电站锅炉运行现状，提出了多层次模糊评判作为吹灰优化方法。借助模糊数学理论，将吹灰优化问题转化为将监测结果与评判所需的单因素决策即模糊映射关联起来的问题和因素权重合理确定的问题。针对电站锅炉的五种吹灰收益，定义了五个收益评判参数，来判断灰污对锅炉五个方面的影响和最大吹灰收益。创新地浙江大学博士学位论文杨卫娟定义了受热面相对吸热比例和烟道相对阻力系数用以判断受热面吹灰的调节性收益和烟道流通通畅状态。综合受热面清洁因子和五个收益评判参数，提出了一个系统的电站锅炉吹灰运行优化的方法，并完成了电站锅炉吹灰运行优化咨询系统的基础设计和建构。此系统是多目标优化吹灰，兼顾到锅炉汽机短期和长期运行的安全性、经济性、调节性和环保性。在提供最佳吹灰方案的同时，也提供最佳吹灰方案的优点和缺点。就电站锅炉吹灰优化专家运行咨询系统的整体运行过程加以说明，并以高温过热器和炉膛为例，详细讲解单目标吹灰优化和多目标吹灰模糊评判的具体优化运行步骤。最后对吹灰优化运行的具体经济效益做了详细的分析，得出对象锅炉由投运尾部受热面吹灰器降低锅炉排烟温度，年节约开支2妇万元左右。更多还原

【Abstract】 Slag and ash deposit on coal-fired boiler in thermal power plant not only decrease the boiler efficiency and the plant economy, but also are hidden trouble of many safety accident. And Sootblowing is an effective and common means to account for this problem. Aiming at the status that the use ratio and skill of the sootblowers in plant at home are poor, the research on online monitoring of ash deposit and slag and sootblowing optimization is carried out. The research takes No. 1 boiler of the Beilun power plant in Ningbo as an example, which load is 600 MW electricity.Firstly, the spontaneous drop of slag on walltube at the time of boiler load shift is researched and it is the innovative research on the effect on the slagging of boiler operation. It is gained from presenting mechanism of slag thermal stress that the slag thermal stress is composed of slag shaping thermal stress and temperature grads thermal stress. Model is built to calculate slag thermal stress. And it is calculated and analyzed the distribution and quantity of slag thermal stress created by boiler load shift. Thermal stress quantity can be as big as E/1000 and is enough to destroy slag structure and to make some drop. It is also concluded that the walltube parameters can only affect on thermal stress of the slag that is near to contact surface and contribute little to slag drop. The stress of slag rests with the structure, physical characteristic, and heat transfer status of slag. Taking NO. 1 boiler of Beilun Thermal Power Plant as example, the walltube thermal stress and the destroying impact on slag are researched. And the conclusion is that Downing load can distory the small slag and outer part of thick slag, which is helpful to keep walltube clean and useless for preventing from furnace accident caused by slag.The ash fouling online monitoring models are built for furnace, convection heating surface and tri-sectional regenerative air preheater based on the analysis and summarization the researches on the ash fouling monitoring technic and models of boiler. Clean factor (CF) is chosen to express the effect on heat transfer of ash fouling and is calculated by heat transfer steady-state model. Thus clean factor has good adaptability to boiler load, coal quality, excess air coefficient, working medium flow, and boiler efficiency etc. The calculated result gained by inputting the data of history database of the object boiler validates the correctness and adaptability to boiler load of clean factor model. The CF correlation of some monitored modules and the CF sensitivity to sootblowing are studied and analyzed from the view of the characteristic of heating surface itself and measuring point collocation. The error transfer law is researched from operation data calculation and mathematic theory to find out how the measurement error of main monitored parameters influences the clean factor. And the law gained from differential calculus is coincident well with the calculated result.Grounded upon the research on the sootblower operation, the effect on all kinds of boilerperformance of ash fouling on heating surface is analyzed roundly. And the sootblowing income is divided into five categories. So is the sootblowing cost. It is concluded that the categories of sootblowing income and cost on different heating surface are not all the same. The method to calculate accurately the income and cost is studied. The magnitude of all income and cost categories is calculated and compared by calculating the boiler performance change with the clean factor. The minimum income is the electricity reducing of draft fan and the minimum cost is the electricity cost of sootblower drive. Also it is gathered that sootblowing reasonably can bring about several decuple profit compared with the sootblowing cost.The boundary and content of sootblowing operation optimization are defined afresh. The optimized goal of sootblowing is set a tradeoff between all categories of sootblowing income and cost and the optimized unit is a single monitored surface modul更多还原