【作者】 周鸿波；

【导师】 童水光； 钟崴；

【作者基本信息】 浙江大学 ， 化工过程机械， 2008， 博士

【摘要】 循环流化床是近二十年来在国际上快速发展起来的新一代高效低污染清洁燃烧技术,不仅能实现90%的脱硫效率、低NO_x排放和与煤粉炉相近的燃烧效率,并且还具有广泛的燃料适应性和优良的负荷调节性能等众多优点,因此在国际上得到迅速的商业推广。循环流化床锅炉方案设计是一项复杂繁琐、经验性强、设计周期长、可靠性和经济性要求高的大型工程,需要设计人员具备大量、全面的知识。因此,研究将具有多样性、复杂性、经验性和不确定性等特点的循环流化床锅炉方案设计知识形式化、数字化并以显示的方式存储起来,用于提高循环流化床锅炉方案设计的智能化进程、缩短设计周期、降低设计成本,是计算机辅助锅炉设计技术领域的前沿研究课题之一。本论文在“十一五”国家科技支撑计划项目(2006BAF01A46)和浙江省科技计划项目(2006C21SA160008)的资助下,研究了循环流化床锅炉方案设计的计算机辅助设计方法,并将知识工程与之融合起来,提出一种能支持整个循环流化床锅炉方案设计进程的智能设计技术,其主要研究内容如下:在对方案设计活动进行认知和分解的基础上,把循环流化床锅炉方案设计活动分解为“方案创建”、“方案分析”、“方案评价”和“方案优化”四项子进程,并提出了一种集成的方案智能设计方法:采用基于实例推理的方法进行方案创建;在过程系统理论的基础上搭建设计方案的模型、并进行分析和求解;采用基于规则推理的方法对设计方案进行评价;最后根据评价结果对设计方案进行优化。循环流化床锅炉方案设计需要进行热力计算、烟风阻力计算和水动力计算等多项内容,采用集成化的设计思想把需要完成的计算功能设计成一个整体,各计算功能之间实现数据调用、代码重用和功能共享;利用过程系统的理论认识锅炉系统,把锅炉分解成以“部件单元”和“流体线”为基本构成单位的网状模型,采用图形化建模工具分流程搭建分析模型,并以序贯模块法对模型进行自动求解。提出了一种基于经验的循环流化床锅炉炉膛部分的统一传热计算模型。该模型采用沿高度方向的一维分区段计算方法,有效地解决炉膛中固体颗粒浓度和受热面不均匀分布的问题;筛选出传热系数、烟气中的固体颗粒浓度、燃料的燃烧份额等需要凭经验取值的热力参数,推导了区段热量衡算的通用计算公式;并计算了该模型在脱硫时炉膛热量、灰分和烟气成分的变化。采用基于实例推理的方法构造了循环流化床锅炉方案创建和分析子系统的模型结构。首先对过去已完成的设计方案进行了分解,设计了一种分层次多实例库的结构来存储设计方案和参数,该结构有利于提高检索的效果与效率;采用动态可配置的方式定制索引;提出了一种基于数理统计的最邻近法用于检索相似的实例,该方法不需要人为设定特征权重参数就能自动检索出属性最为接近的实例集合。采用基于规则推理的方法进行循环流化床锅炉方案评价。对评价过程中需要用到的知识进行了认识和分类;把方案评价分解为输入模型正确性检查、计算结果可行性判断以及方案性能优良性分析三个子过程;推理机采用目标驱动的控制策略,推理时仅考虑与当前评价内容有关的规则,从而提高系统推理的准确度和效率。更多还原

【Abstract】 Circulating Fluidized Bed (CFB) is a new generation of clean combustion technology with high-efficiency and low-pollution in recent twenty years. CFB can not only realize 90% desulfurization efficiency, low emission of NOx and similar combustion efficiency compared with pulverized coal fired boiler, but also has many advantages, such as wild fuel adaptability and excellent performance of load adjustment. Therefore, it gets rapid and worldwide dissemination for business.The Scheme design of CFB boiler is a complex, highly empirical, long-term, highly reliability and economical efficiency required project, which needs researchers rich in the relative knowledge and experience. It is one of the frontier topics in the technique of computer aided designing boilers that stores the knowledge of CFB boiler in the way of digitalization to enhance the intelligent process of CFB boiler design, shorten design period and reduce design cost. The paper was in the subsidization of "eleventh-five national science and technology support plan projects" (2006BAF01A46) and Zhejiang Technology Plan Program (2006C21SA160008) and researched the computer aided method of CFB boiler scheme design. In addition, it combined the method of knowledge engineering to explore an intelligent solving technology supporting the whole research cycle of scheme design. The main research contents on this subject were explained as follows:Based on the cognition of the research process, the scheme design of CFB boiler was divided into four courses: scheme design, scheme analysisg, scheme evaluation and scheme optimization. Moreover, an integrated method of intelligent design was applied to the research: the scheme was established by the method of case study based reasoning; the model of scheme was structured and solved based on the theory of process system; the scheme was evaluated by the method of rule based reasoning. In the end, the scheme would be optimized according to the evaluated results.The scheme design of CFB boiler need to do a lot of calculations, such as thermal calculation, smoke resistance calculation and (hydrodynamic calculation. Design a model which include all calculations by adopting the thinking of integration, realize the function of data transferring, code reusing and tools sharing in calculations. Cognate the CFB boiler as network model by the made of part element and fluid dram line in the view of process system, using sequential modular method to solve the model automatically.Propose a CFB boiler heat transfer calculation model based on experience. The model solved the problem that ash concentration and heating surface were inhomogeneous distribution by the method of divide the furnace into serial sections in the height direction. Picked out empirical parameters, such as heat transfer coefficients, ash concentration and combustion fraction of fuel, derivate general formulas in heat balance calculations of section, calculate the change of heat, ash, smoke components of furnace in the condition of desulfurization.Propose case based reasoning method to structure the model of design and modify scheme system. Firstly, disassembled past design scheme, proposed a model of level-division and multi-library to storage cases. The library model was beneficial to heighten an effort and improve efficiency. Secondly, adopted the method of dynamic configuration to customize the index. In the end, proposed a kind of nearest neighbor algorithm based on mathematical statistics to retrieval cases. The nearest neighbor algorithm could find out the most similar cases automatically without setting feature weights.Propose rule based reasoning method to evaluative scheme CFB boiler. Cognized and classified the knowledge in process of evaluation, decomposed the process of evaluating scheme into three sub processes: correctness checking of inputted model, feasibility judgment of calculation results and performance analysis of scheme. Inference engine used control strategy of goal-driven, which only search the related rules, to improve efficiency and accuracy.更多还原