炉膛受热面防护复合陶瓷涂层性能及提升传热效果研究

发布时间：2018-06-16 10:24

本文选题：热化学反应法 + 复合陶瓷涂层　；参考：《中国计量学院》2016年硕士论文

【摘要】：针对锅炉受热面的结渣和高温腐蚀问题,采用热化学反应法在钢材表面制备了一种复合陶瓷涂层,对该涂层进行了抗热震、抗高温氧化、抗熔盐腐蚀、发射率以及热导率等性能试验。并用Fluent模拟在锅炉不同区域喷涂涂层后对于锅炉炉膛换热性能的影响,确定最佳喷涂位置,为工程应用提供指导。首先,分别在5种锅炉常用钢材(20G、12Cr1MoVG、15CrMoG、T91、TP347)制备了复合陶瓷涂层,并通过SEM结合EDS等技术手段对涂层样片进行微观形貌、物相组成等分析。对涂层样片进行了抗热震性能、抗高温氧化性能、抗熔盐腐蚀性能、发射率、热导率的性能测试。试验结果表明:涂层具有较好的抗热震性能,随着涂层厚度增加,抗热震性能呈线性下降;涂层抗高温氧化性能较基体钢材有较大提升;涂层抗熔盐腐蚀性能较基体钢材有一定提升;涂层样片红外波段发射率达到0.9;涂层样片与钢材样片热导率接近。其次,对一台670 t/h锅炉的水冷壁与大屏部分区域喷涂涂层,实际运行出现过热蒸汽欠温问题,针对这一问题,使用Fluent进行锅炉数值模拟,研究表明:在水冷壁喷涂复合陶瓷涂层后吸热量增加导致过热器吸热量不足,从而导致过热蒸汽欠温问题。通过改变炉膛水冷壁及过热器复合陶瓷涂层面积进行数值模拟,结果表明:在水冷壁喷涂面积基础上增加过热器喷涂面积可以提高过热器吸热量,从而保证过热蒸汽温度,同时降低炉膛出口烟温。本文也对在大屏过热器上全部喷涂陶瓷涂层的条件下,改变磨煤机投运层数,即改变火焰中心高度进行数值模拟。
[Abstract]:In order to solve the problem of slagging and high temperature corrosion of boiler heating surface, a kind of composite ceramic coating was prepared on steel surface by thermal chemical reaction method. The coating was subjected to thermal shock resistance, high temperature oxidation resistance and molten salt corrosion resistance. Emissivity, thermal conductivity and other performance tests. Fluent is used to simulate the influence of sprayed coating on the heat transfer performance of boiler furnace after spraying in different areas of boiler. The optimum spraying position is determined and the guidance for engineering application is provided. Firstly, composite ceramic coatings were prepared in five kinds of common boiler steels, such as 20G / 12Cr1MoVG / 15CrMoG / T91 / TP347). The microstructure and phase composition of the coating samples were analyzed by means of SEM and EDS. The thermal shock resistance, oxidation resistance, molten salt corrosion resistance, emissivity and thermal conductivity of the coating samples were tested. The results show that the coating has better thermal shock resistance, and the thermal shock resistance decreases linearly with the increase of coating thickness, and the high temperature oxidation resistance of the coating is much higher than that of the substrate steel. The corrosion resistance of the coating is better than that of the steel substrate. The infrared emissivity of the coating sample is 0.9.The thermal conductivity of the coating sample is close to that of the steel sample. Secondly, for a 670 t / h boiler with spray coating on the water wall and part of the large screen, the problem of overheated steam undertemperature appears in actual operation. In view of this problem, the boiler is simulated numerically by fluent. The results show that the increase of the heat absorption of the superheater after spraying the composite ceramic coating on the water wall leads to the undertemperature of the superheated steam. By changing the area of water wall and superheater composite ceramic coating in furnace, the results show that increasing the spray area of superheater on the basis of spraying area of water wall can increase the heat absorption of superheater and ensure the superheated steam temperature. At the same time, the flue gas temperature of furnace outlet is reduced. In this paper, numerical simulation is also carried out to change the number of pulverizer layers, that is, the height of flame center, when all ceramic coatings are sprayed on the large screen superheater.
【学位授予单位】：中国计量学院
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TK223;TG174.4

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