热电偶熔敷埋设法测量CFB锅炉壁温的实验研究
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摘要
受热面管壁温度是反映锅炉安全的重要参数。在循环流化床(CFB)锅炉中,由于炉膛和流化床换热器中高浓度固体颗粒物对受热面的剧烈冲刷,故在壁温测量中,传统放置热电偶的方法不可用。该文提出了一种可以应用于CFB锅炉的受热面壁温测量的方法:热电偶熔敷埋设法,即将热电偶贴壁式放置在待测锅炉受热面壁面上,熔敷金属熔化后敷设在热电偶表面形成熔敷层。通过实验对于所述测温方法进行可行性验证,针对两种不同的熔敷金属形状,比较实际管壁温度和所提出方法的测量值,并给出了实际管壁温度的计算方法。结果表明:在不同工况下,两种熔敷金属形状的测量值与实际管壁温度的偏差分别在±3℃和±7℃之内,该方法可以应用于锅炉受热面壁温的测量。
Heating surface tube-wall temperatures are key parameters for boiler safety. The high solids concentration in circulating fluidized bed(CFB)boilers complicates installation of thermocouples in the furnace or the fluidized bed heat exchanger.This paper describes a method for embedding thermocouples using deposited metal to measure the tube-wall temperatures in CFB boilers.The method was evaluated experimentally with two deposition shapes with the heat transfer between the thermocouple and the tube-wall analyzed to calculate the actual tube-wall temperature without the deposited metal.The results show that the differences between the measured and actual temperatures of the tube-wall without the deposited metal for the two deposition shapes were about±3℃ and±7℃ for various working conditions.Thus,this method can be applied to measure tube-wall temperatures in CFB boilers.
Heating surface tube-wall temperatures are key parameters for boiler safety. The high solids concentration in circulating fluidized bed(CFB)boilers complicates installation of thermocouples in the furnace or the fluidized bed heat exchanger.This paper describes a method for embedding thermocouples using deposited metal to measure the tube-wall temperatures in CFB boilers.The method was evaluated experimentally with two deposition shapes with the heat transfer between the thermocouple and the tube-wall analyzed to calculate the actual tube-wall temperature without the deposited metal.The results show that the differences between the measured and actual temperatures of the tube-wall without the deposited metal for the two deposition shapes were about±3℃ and±7℃ for various working conditions.Thus,this method can be applied to measure tube-wall temperatures in CFB boilers.
引文
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[2]邹天舒,冷杰,吴景兴,等.超临界直流锅炉膜式水冷壁温度的测量方法:CN200710010198.1[P].2007-09-12.ZOU T S,LENG J,WU J X,et al.Measuring method for temperature of supercritical once-through boiler membrane wall:CN200710010198.1[P].2007-09-12.(in Chinese)
[3]张继锋.循环流化床水冷壁内传热的计算和实验研究[D].北京:清华大学,1998.ZHANG J F.Numerical and experimental study on heat transfer in the circulating fluidized bed water-wall[D].Beijing:Tsinghua University,1998.(in Chinese)
[4]ZHANG Z Z,SUN B M,XU H,et al.Study on correlation of key points temperature of membrane water wall[C]//Proceedings of the ASME 2005International Mechanical Engineering Congress and Exposition,Orlando:ASME,2005:15-20.
[5]BASU P,NAG P K.Heat transfer to walls of a circulating fluidized-bed furnace[J].Chemical Engineering Science,1996,51(1):1-26.
[6]LU J F,YU L,YUE G X,et al.Heat flux distribution on circulating fluidized bed boiler water wall[J].Frontiers of Energy&Power Engineering in China,2008,2(2):134-139.
[7]李金晶,李燕,吕俊复,等.循环流化床锅炉炉内传热的影响因素[J].清华大学学报(自然科学版),2007,47(11):2026-2030.LI J J,LI Y,LJ F,et al.Factors affecting the heat transfer in a circulating fluidized bed boiler[J].Journal of Tsinghua University(Science and Technology),2007,47(11):2026-2030.(in Chinese)
[8]DUDA P,TALER J.A new method for identification of thermal boundary conditions in water-wall tubes of boiler furnaces[J].International Journal of Heat&Mass Transfer,2009,52(5):1517-1524.
[9]张瑞卿,杨海瑞,吕俊复,等.循环流化床锅炉炉膛的传热计算,动力工程学报,2011,31(4):248-252.ZHANG R Q,YANG H R,LJ F,et al.Calculation of heat transfer in furnace of a circulating fluidized bed boiler[J].Journal of Chinese Society of Power Engineering,2011,31(4):248-252.(in Chinese)
[10]LUAN W,BOWEN B D,LIM C J,et al.Suspension-to-membrane-wall heat transfer in a circulating fluidized bed combustor[J].International Journal of Heat&Mass Transfer,2000,43(7):1173-1185.
[11]CHINSUWAN A,DUTTA A.An experimental investigation of the effect of longitudinal fin orientation on heat transfer in membrane water wall tubes in a circulating fluidized bed[J].International Journal of Heat&Mass Transfer,2009,52(5):1552-1560.
[12]章熙民,朱彤,安青松,等.传热学[M].北京:中国建筑工业出版社,2014.ZHANG X M,ZHU T,AN Q S,et al.Heat transfer[M].Beijing:China Architecture&Building Press,2014.(in Chinese)