【作者】 申春梅；

【导师】 吴少华；

【作者基本信息】 哈尔滨工业大学 ， 热能工程， 2006， 硕士

【摘要】 随着电力需求的增长和对环保问题的日益重视,具有容量大﹑效率高﹑能耗低﹑可靠性高和环境污染小等特点,且技术已相对成熟的超超临界发电机组,成为目前我国洁净煤发电技术的必然选择。锅炉向超大容量发展后,单炉膛双切圆燃烧方式得到发展,并在国外得到广泛应用,国内对这种燃烧方式研究很少,我国引进的首台1000MW超超临界锅炉也采用此种燃烧方式。本文采用计算流体学软件PHOENICS,对国内首台1000MW单炉膛双切圆超超临界锅炉炉内燃烧过程进行了数值模拟研究,得出了单炉膛双切圆燃烧方式下炉内流场、温度场的分布规律,燃烧器运行参数对炉内燃烧过程以及氮氧化物排放的影响规律,磨煤机不同投运方式对炉内温度场、热负荷分布、烟气成分分布以及氮氧化物排放的影响规律。此外本文对80%、60%和40%额定负荷的低负荷运行工况进行了数值模拟研究,对锅炉的低负荷稳燃特性进行了预测。在炉内过程数值模拟中,气相湍流流动采用k-ε双方程模型,气固两相流动采用基于IPSA算法的双流体模型,辐射传热采用六通量热流法,水份蒸发采用扩散模型,挥发分析出采用单步反应模型,挥发分燃烧采用EBU-Arrhenius模型,焦炭燃烧采用扩散-动力模型。在NO的数值模拟中,将NO生成的数值模拟作为炉内过程数值模拟的后处理过程,采用扩展的Zeldovich机理描述热力型NO的生成,采用De’Soete提出的HCN衰减总体反应机理描述燃料型NO的生成,考虑了焦炭对NO的还原作用,忽略快速型NO的生成。采用有限差分法来离散微分方程,对控制方程的求解采用SIMPLEST算法,在直角坐标系下的非均匀交错网格系统中求解。本文的研究表明,采用合适的数学模型和计算方法,进行燃煤锅炉炉内过程的数值模拟是可行的,对炉膛内温度场和各种组分浓度场的分布特性的模拟是合理的,反映了实际的炉内流动、传热、燃烧和NO生成过程。本文的研究结果,对超超临界燃煤发电引进技术的消化、吸收和进一步的自主研发具有重要的现实意义。本研究是国家863计划课题“超超临界燃煤发电技术”的一部分,已通过课题验收。更多还原

【Abstract】 With the increasing requirement for electric power and the attention of environmental protection,USC power generation,for its characteristics of high-duty, high-efficiency,low-energy consumption,excellent environmental protection and relatively matured technology, is the only way for China’s clean coal technologies. With the development of super-high-duty boiler, single chamber dual circle tangential firing technology was developed,and has been widely used at abroad,and was also applied on the first USC boiler in China.But it was rarely reasearched at home.This thesis numerically simulated pulverized coal combustion process in the first 1000 MW dual circle tangential firing single chamber USC boiler in China, employing the Computational Fluid Dynamics (CFD) code PHOENICS.The numerical results showed the temperature profile and flow field distribute law of dual circle tangential firing single chamber boiler,and also showed the effect of different commission mode of pulverizing coal mill on temperature profile,heat duty, concentration distributions of the combustion species in furnace and overal NOx emission level of the boiler.In addition, three different cases with 80%, 60% and 40% boiler full load were simulated,to evaluate the sustained combustion characteristic of part load operation.In the numerical calculation of furnace process, the turbulence is accounted for by conventional k-εtwo equations model. The two fluid model based on Inter-phase Slip Algorithm is employed for the two-phase flow simulation. Radiation uses the Six-Flux model. Particle drying is modeled by diffusion model. The devolatilization process is modeled by one step reaction model. Turbulent combustion of volatiles is modeled by EBU-Arrhenius model. Char combustion is modeled by diffusion-kinetics model. In the numerical simulation of NO emission, a post-processing run is employed for the NO simulation based on the results of the main combustion process in the furnace. Thermal NO is predicted using the extended Zeldovich mechanism. The Fuel NO calculation is performed using equations for HCN and NO transport with the reaction mechanisms proposed by De’Soete. The deoxidization effect of char to NO is considered and prompt NO is overlooked. The governing equations are discretized over a non-uniform staggered grid in the Cartesian coordinate using the finite difference method and the equations are solved by SIMPLEST algorithm.This thesis shows that numerical simulation of furnace process in pulverized coal fired boiler with proper mathematical models and calculation method is viable. The numerical simulation of temperature field and the concentration distributions of the combustion species in the furnace are reasonable and they can reveal the actual flow, heat transfer, combustion process and NO emission in boiler furnaces.This above results of this thesis have significant practical importance to absorb the super high duty generate electricity technology introduced from abroad, and also to the reaearch and development of our own. This subject is part of China’s National High Tech. R&D Program“USC power generation technologies”and research results have been accepted by experts.更多还原