660MW超临界锅炉低氮燃烧器改造后的炉内特性研究

发布时间：2018-04-13 05:08

本文选题：超临界锅炉 + 四角切圆　；参考：《华北电力大学》2017年硕士论文

【摘要】：本文利用Fluent数值模拟软件,对某电厂660MW超临界锅炉四角切圆燃烧器在炉膛内的燃烧过程进行了模拟,并对各个工况下的模拟结果进行理论分析,分析过程中结合实际运行数据,指出结果中存在的问题,模拟结果能够较为真实反映锅炉运行状况。首先,利用Gambit软件对锅炉本体进行了全尺寸建模,针对四角切圆的燃烧方式,在燃烧器区进行分区域划分网格,网格走向与煤粉射流方向保持一致,有效减少了伪扩散的发生。根据锅炉炉型、燃烧器的布置方式及配风方式等,作为选择数学物理模型的依据,其中,湍流模型选用Realizable k-ε模型,采用拉格朗日法对气固两相湍流流动过程进行求解,煤粉颗粒追踪采用随机轨道模型,挥发分燃烧模型采用平衡混合分数/PDF模型,焦炭燃烧模型为动力学/扩散反应速率模型,辐射传热模型采用P-1辐射模型,NO_x生成采用后处理的方法计算。通过对不同工况下的燃烧模拟所得到的结果:三种不同负荷下的炉内速度场、氧气、二氧化碳和NO_x组分浓度场、温度场,分析了三种工况下炉膛内不同区域处的流动及燃烧特点后发现,满负荷时下一次风区域存在热偏差现象,上层CFS风出现了一次风煤粉气流刷墙的情况;改变炉内氧量,分析了四种过量空气系数下的燃烧情况,对比四种工况下的炉内速度场、温度分布情况,得出较为合适的过量空气系数为1.15;改变SOFA风水平摆角会减轻附近受热面结焦情况并改善汽温调节性能;在一定范围内减小凑燃尽风CCOFA和预置水平偏角的CFS二次风挡板开度会减小炉内NO_x以及炉膛出口NO_x浓度。本文对各种工况进行了模拟,并对结果进行了客观分析,把分析结果与实测数据和实际运行工况进行对比,模拟结果能够反映实际状况,对超临界锅炉在燃烧调整和减少NO_x方面提供了实际参考价值。
[Abstract]:In this paper, the combustion process of a 660MW supercritical boiler's tangential burner in a power plant is simulated by using Fluent software. The simulation results under various working conditions are analyzed theoretically, and the actual operation data are analyzed.The problems existing in the results are pointed out, and the simulation results can reflect the boiler operation status.First of all, the full-scale modeling of boiler body is carried out by using Gambit software. Aiming at the combustion mode of tangent circle in four corners, the combustion zone is divided into different areas and the grid direction is consistent with the direction of pulverized coal jet, which effectively reduces the occurrence of pseudo-diffusion.According to boiler type, burner layout and air distribution, as the basis of selecting mathematical and physical model, Realizable k- 蔚 model is selected for turbulent model and Lagrangian method is used to solve the gas-solid two-phase turbulent flow process.The random track model is used for pulverized coal particle tracking, the equilibrium mixing fraction / PDF model is used for volatile combustion model, and the coke combustion model is kinetic / diffusion reaction rate model.The radiative heat transfer model is calculated by post-processing method using P-1 radiation model.The results obtained from combustion simulation under different operating conditions are as follows: velocity field, concentration field of oxygen, carbon dioxide and NO_x components, temperature field under three different loads.After analyzing the flow and combustion characteristics of different areas in the furnace under three operating conditions, it is found that there is a phenomenon of heat deviation in the primary air area at full load, and the upper CFS wind appears the primary air pulverized coal flow scrubbing wall, and the oxygen content in the furnace is changed.The combustion conditions under four kinds of excess air coefficients are analyzed, and the velocity field and temperature distribution in the furnace under four operating conditions are compared.The suitable excess air coefficient is 1. 15. Changing the horizontal swing angle of SOFA wind can reduce the coking of the nearby heating surface and improve the performance of steam temperature regulation.In a certain range, the NO_x and NO_x concentration at the outlet of the furnace will be reduced by decreasing the opening of the CFS secondary windshield and the pre-setting horizontal deflection angle.In this paper, various working conditions are simulated, and the results are analyzed objectively. The results are compared with the measured data and the actual operating conditions. The simulation results can reflect the actual situation.It provides practical reference value for supercritical boiler in combustion adjustment and reduction of NO_x.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM621.2

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