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In large-scale p. f. fired boilers, large deviations of flue gas temperature and velocity often exist at furnace exit and at horizontal flue pass along furnace width, making overheat, ash accumulation and slag boding of convection heating surface. Tests on a 2000MW utility boiler affirm:flue gas temperature deviation on convection heating surface arive from velocity deviation, which arise from residual rotation at furnace exit. Residual rotation at furnace exit can be eliminated by decreasing revolving... In large-scale p. f. fired boilers, large deviations of flue gas temperature and velocity often exist at furnace exit and at horizontal flue pass along furnace width, making overheat, ash accumulation and slag boding of convection heating surface. Tests on a 2000MW utility boiler affirm:flue gas temperature deviation on convection heating surface arive from velocity deviation, which arise from residual rotation at furnace exit. Residual rotation at furnace exit can be eliminated by decreasing revolving intensity of airflow in furnace. Through injecting overheated air anti-tangentially into furnace, results show: residual ratation at furnace exit becomes small, an uniform velocity distribution along furnace width can be expected on horizontal flue pass, and aerodynamics in furnace is less affected. 某电厂200MW机组的冷、热态试验结果表明:高温对流受热面的烟气温度偏差是由速度偏差引起的,而水平烟道中的烟速不均是由于炉膛出口的残余扭转引起的,消除和削弱炉膛出口的残余扭转就应使炉内气流的旋转强度减弱。因此,在冷态模化试验台上进行了三次风反切的试验研究,结果发现:通过三次风反切,能够削弱炉膛出口的扭转残余,在水平烟道中形成一个较为均匀的速度分布,且对炉内空气动力结构无明显影响,这对机组的安全经济运行起促进作用。 Based on a coal fired boiler of 300MW unit in Shiheng power plant, Shandong province of China,the study of numerical simulation on flue gas temperature deviation in the upper part of the furnace is presented in this paper.The mathematical models,the calculeted results of the relative diameter of the tangential circle,the mixing intensity of gases, the full extent of flame in the furnace,the after twirl at the exit of the furnace as well as the temperature and velocity distribution at different cases... Based on a coal fired boiler of 300MW unit in Shiheng power plant, Shandong province of China,the study of numerical simulation on flue gas temperature deviation in the upper part of the furnace is presented in this paper.The mathematical models,the calculeted results of the relative diameter of the tangential circle,the mixing intensity of gases, the full extent of flame in the furnace,the after twirl at the exit of the furnace as well as the temperature and velocity distribution at different cases are presented. The effects of the directions of the primary and secondary air, the plate superheater,and the diameter of the tangential circle of the secondary air on gas temperature deviation are discussed. Finally, the means to decrease the deviation are introduced. 本文以山东石横电厂300MW机组配套燃煤锅炉为研究对象,对大型四角切向喷燃锅炉中普遍存在的烟温、汽温偏差的原因及改进措施进行了数值模拟。文中介绍了所采用的数学模型、处理方法,给出了不同工况下炉内相对实际切圆直径、气流混合强度、火焰充满度、炉膛出口残余扭转以及炉内不同截面上的温度分布、速度分布的计算结果,探讨了一、二次风气流旋转方向、屏式过热器、二次风切园直径等对烟温、汽温偏差的影响,提出了减小烟温、汽温偏差的方法和措施。 In order to prevent slagging in furnaces of high - capacity utility boilers, and to decrease flue gas temperature deviation on convective heating surfaces, this paper presents the concentric firing system (CFS) with anti-tangential secondary air. Through a series of investigations of aerodynamics and particle movement characteristics by cold model test and numerical simulation, the paper obtains that anti-tangential secondary air can concentrate coal particles at furnace center, prevent slagging in furnace,... In order to prevent slagging in furnaces of high - capacity utility boilers, and to decrease flue gas temperature deviation on convective heating surfaces, this paper presents the concentric firing system (CFS) with anti-tangential secondary air. Through a series of investigations of aerodynamics and particle movement characteristics by cold model test and numerical simulation, the paper obtains that anti-tangential secondary air can concentrate coal particles at furnace center, prevent slagging in furnace, and get a well-distributed gas velocity and particles in convective flue gas passage. 为了防止大型电站锅炉炉内结渣,减轻高温对流受热面处烟气温度偏差,本文提出了二次风燃烧器喷口反切布置的同心圆燃烧方式。通过对炉内气相流动的冷模试验研究和数值模拟,单颗粒炉内运动的数值模拟和颗粒群在炉内运动的冷态试验研究结果表明:合理的二次风反切可在炉内形成“风包粉”燃烧方式,且使水平烟道内高温对流受热面处的气流速度和颗粒得到均匀分布,这对防止炉内结渣、减轻高温对流受热面热偏差起促进作用。
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