跨临界变压运行中水冷壁动态特性的实验研究
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摘要
针对超临界直流锅炉水冷壁系统在跨临界变压运行过程中的特殊流动与传热现象,在压力为19～25MPa、质量流速为300～800kg/(m~2·s)、外壁热流密度为60～250kW/m~2的工况范围内,对垂直上升受热管道内超临界水在跨临界动态过程中的流动与传热特性开展了实验研究。结果表明:在从超临界压力阶跃降低至亚临界压力的动态过程中,受热管内流体极其容易发生壁温飞升现象,该现象由近临界区流体发生的膜态沸腾(又称DNB传热恶化)引起。在近临界压力区,随着压力的升高并逐渐靠近临界压力,发生DNB传热恶化时的起始局部流体焓值会大幅度降低,而且恶化程度逐渐增强,本实验大多数工况甚至在过冷区就开始发生传热恶化现象,严重威胁锅炉水冷壁系统的安全运行。基于本文实验结果和对锅炉水冷壁系统运行的分析认为,当管内的局部流体焓值高于1 600kJ/kg时,水冷壁系统在跨临界动态过程中极有可能出现DNB传热恶化现象。本文实验结果可为超临界锅炉水冷壁系统跨临界变压运行期间的工况设计和调节提供指导。
Aiming at the special flow and heat transfer characteristics in the transcritical variablepressure operating process of the water-wall in the supercritical once through boiler,experiments were conducted to investigate the transcritical dynamic flow and heat transfer characteristics in a vertical upward heated pipe under 19-25 MPa of pressure,300-800 kg/(m~2·s)of mass velocity and 60-250 kW/m~2 of heat flux on the pipe outerwall.The experimental results showed that a wall temperature rise always occurs in the transcritical dynamic process of the heated pipe,which is caused by the DNB heat transfer deterioration in the near-critical pressure region.With the increase of the fluid pressure,the nearer is the fluid pressure close to the critical point,the lower is the fluid enthalpy needed to induce the occurrence of DNB,and the higher the deterioration degree will be.Moreover,DNB heat transfer deterioration even occurs when the working fluid is still in a subcooled state under most of our experimental cases,and this seriously threats the safe running of the water-wall system.Based on the parameter range of our experiments and the analysis on the operation of water-wall,DNB heat transfer deterioration is likely to occur in thetranscritical dynamic process when the local fluid enthalpy in the heated pipe is higher than 1 600 kJ/kg.The experimental results in this research can provide a guidance for the design and adjustment of the operation conditions in the water-wall of the supercritical once through boiler.
Aiming at the special flow and heat transfer characteristics in the transcritical variablepressure operating process of the water-wall in the supercritical once through boiler,experiments were conducted to investigate the transcritical dynamic flow and heat transfer characteristics in a vertical upward heated pipe under 19-25 MPa of pressure,300-800 kg/(m~2·s)of mass velocity and 60-250 kW/m~2 of heat flux on the pipe outerwall.The experimental results showed that a wall temperature rise always occurs in the transcritical dynamic process of the heated pipe,which is caused by the DNB heat transfer deterioration in the near-critical pressure region.With the increase of the fluid pressure,the nearer is the fluid pressure close to the critical point,the lower is the fluid enthalpy needed to induce the occurrence of DNB,and the higher the deterioration degree will be.Moreover,DNB heat transfer deterioration even occurs when the working fluid is still in a subcooled state under most of our experimental cases,and this seriously threats the safe running of the water-wall system.Based on the parameter range of our experiments and the analysis on the operation of water-wall,DNB heat transfer deterioration is likely to occur in thetranscritical dynamic process when the local fluid enthalpy in the heated pipe is higher than 1 600 kJ/kg.The experimental results in this research can provide a guidance for the design and adjustment of the operation conditions in the water-wall of the supercritical once through boiler.
引文
[1]樊泉桂.超超临界锅炉设计及运行[M].北京:中国电力出版社,2010:1-2.
[2]黄锦涛,陈听宽.超临界直流锅炉螺旋管圈水冷壁动态特性[J].锅炉技术,2000,31(1):12-17.HUANG Jintao,CHEN Tingkuan.Dynamic characteristic of spiral wall evaporating heating surface in supercritical once-through boiler[J].Boiler Technology,2000,31(1):12-17.
[3] DUFFEY R B,PIORO I L.Heat transfer and hydraulic resistance at supercritical pressures in power engineering applications[M].New York,USA:ASME Press,2007:5-16.
[4]刘树青,余圣方,周龙.900 MW超临界直流锅炉蒸发器数学模型与仿真研究[J].计算机仿真,2005,22(10):215-217.LIU Shuqing,YU Shengfang,ZHOU Long.Mathematic model and simulation of 900 MW supercritical once-through boiler[J].Computer Simulation,2005,22(10):215-217.
[5]黄永和,杨晨,何航行.超临界直流锅炉水冷壁系统建模与仿真[J].计算机仿真,2013,30(1):314-318.HUANG Yonghe, YANG Chen, HE Hangxing.Model and simulation of water screen system for supercritical once-through boiler[J].Computer Simulation,2013,30(1):314-318.
[6] LI H P,HUANG X J,ZHANG L J.A lumped parameter dynamic model of the helical coiled oncethrough steam generator with movable boundaries[J].Nuclear Engineering and Design,2008,238(7):1657-1663.
[7] LI Y Q,REN T J.Moving boundary modeling study on supercritical boiler evaporator:by using enthalpy to track moving boundary location[C]∥Asia-Pacific Power and Energy Engineering Conference.Piscataway,NJ,USA:IEEE,2009:1-4.
[8]范永胜,徐治皋,陈来九.超临界直流锅炉蒸汽发生器的建模与仿真研究[J].中国电机工程学报,1998,18(4):246-253.FAN Yongsheng,XU Zhigao,CHEN Laijiu.Modelling and simulation study on a supercritical once through boiler steam generator[J].Proceedings of the CSEE,1998,18(4):246-253.
[9]李运泽,杨献勇,张勇,等.超临界直流锅炉蒸发过程的模型与仿真[J].清华大学学报(自然科学版),2002,42(8):1117-1120.LI Yunze,YANG Xianyong,ZHANG Yong,et al.Linear evaporation model for process of supercritical once through boiler[J].Journal of Tsinghua University(Science and Technology),2002,42(8):1117-1120.
[10]常经纬,田晓璇,黄锦涛.基于Simulink的超超临界直流锅炉水冷壁动态特性仿真[J].热力发电,2014,43(2):51-57.CHANG Jingwei,TIAN Xiaoxuan,HUANG Jintao.Simulink based dynamic characteristics simulation for water wall on an ultra supercritical boiler[J].Thermal Power Generation,2014,43(2):51-57.
[11]王建国,李会雄.垂直上升管内临界压力区水的传热恶化研究[J].中国电机工程学报,2011,31(23):67-73.WANG Jianguo,LI Huixong.Investigation on heat transfer deterioration of water in near critical pressure region in vertically upward tubes[J].Proceedings of the CSEE,2011,31(23):67-73.
[12]孙丹,陈听宽,罗毓珊,等.垂直上升光管内临界压力区水的传热特性研究[J].西安交通大学学报,2001,35(1):10-14.SUN Dan,CHEN Tingkuan,LUO Yushan,et al.Research on the heat transfer performance of water in vertical upward smooth tube under near critical pressure[J].Journal of Xi’an Jiaotong University,2001,35(1):10-14.
[13]尹飞,陈听宽,罗毓珊,等.亚临界及近临界压力区倾斜管与垂直管中汽水沸腾传热特性比较[J].中国电机工程学报,2005,25(1):137-141.YIN Fei,CHEN Tingkuan,LUO Yushan,et al.Comparison on the boiling heat transfer characteristic of steam-water in the inclined tube and the vertical tube in sub-critical and near critical pressure regions[J].Proceedings of the CSEE,2005,25(1):137-141.
[14]黄锦涛,陈听宽.单相螺旋管圈动态特性研究[J].热能动力工程,1999,14(5):340-342.HUANG Jintao,CHEN Tingkuan.A study of the dynamic characteristics of single phase spiral tube coils[J].Journal of Engineering for Thermal Energy&Power,1999,14(5):340-342.
[15]傅龙泉,马庆,陈金娥.超临界直流锅炉水冷壁动态特性试验研究[J].上海电力学院学报,1995,11(3):9-17.FU Longquan,MA Qing,CHEN Jine.An experimental research into dynamic characteristics of supercritical once-through boiler water wall[J].Journal of Shanghai Institute of Electric Power,1995,11(3):9-17.
[16]宋明强.跨临界自然循环流动不稳定性研究[D].北京:华北电力大学(北京),2016:71-72.
[17]车得福,庄正宁.锅炉[M].2版.西安:西安电子科技大学出版社,2008:413-420.
[2]黄锦涛,陈听宽.超临界直流锅炉螺旋管圈水冷壁动态特性[J].锅炉技术,2000,31(1):12-17.HUANG Jintao,CHEN Tingkuan.Dynamic characteristic of spiral wall evaporating heating surface in supercritical once-through boiler[J].Boiler Technology,2000,31(1):12-17.
[3] DUFFEY R B,PIORO I L.Heat transfer and hydraulic resistance at supercritical pressures in power engineering applications[M].New York,USA:ASME Press,2007:5-16.
[4]刘树青,余圣方,周龙.900 MW超临界直流锅炉蒸发器数学模型与仿真研究[J].计算机仿真,2005,22(10):215-217.LIU Shuqing,YU Shengfang,ZHOU Long.Mathematic model and simulation of 900 MW supercritical once-through boiler[J].Computer Simulation,2005,22(10):215-217.
[5]黄永和,杨晨,何航行.超临界直流锅炉水冷壁系统建模与仿真[J].计算机仿真,2013,30(1):314-318.HUANG Yonghe, YANG Chen, HE Hangxing.Model and simulation of water screen system for supercritical once-through boiler[J].Computer Simulation,2013,30(1):314-318.
[6] LI H P,HUANG X J,ZHANG L J.A lumped parameter dynamic model of the helical coiled oncethrough steam generator with movable boundaries[J].Nuclear Engineering and Design,2008,238(7):1657-1663.
[7] LI Y Q,REN T J.Moving boundary modeling study on supercritical boiler evaporator:by using enthalpy to track moving boundary location[C]∥Asia-Pacific Power and Energy Engineering Conference.Piscataway,NJ,USA:IEEE,2009:1-4.
[8]范永胜,徐治皋,陈来九.超临界直流锅炉蒸汽发生器的建模与仿真研究[J].中国电机工程学报,1998,18(4):246-253.FAN Yongsheng,XU Zhigao,CHEN Laijiu.Modelling and simulation study on a supercritical once through boiler steam generator[J].Proceedings of the CSEE,1998,18(4):246-253.
[9]李运泽,杨献勇,张勇,等.超临界直流锅炉蒸发过程的模型与仿真[J].清华大学学报(自然科学版),2002,42(8):1117-1120.LI Yunze,YANG Xianyong,ZHANG Yong,et al.Linear evaporation model for process of supercritical once through boiler[J].Journal of Tsinghua University(Science and Technology),2002,42(8):1117-1120.
[10]常经纬,田晓璇,黄锦涛.基于Simulink的超超临界直流锅炉水冷壁动态特性仿真[J].热力发电,2014,43(2):51-57.CHANG Jingwei,TIAN Xiaoxuan,HUANG Jintao.Simulink based dynamic characteristics simulation for water wall on an ultra supercritical boiler[J].Thermal Power Generation,2014,43(2):51-57.
[11]王建国,李会雄.垂直上升管内临界压力区水的传热恶化研究[J].中国电机工程学报,2011,31(23):67-73.WANG Jianguo,LI Huixong.Investigation on heat transfer deterioration of water in near critical pressure region in vertically upward tubes[J].Proceedings of the CSEE,2011,31(23):67-73.
[12]孙丹,陈听宽,罗毓珊,等.垂直上升光管内临界压力区水的传热特性研究[J].西安交通大学学报,2001,35(1):10-14.SUN Dan,CHEN Tingkuan,LUO Yushan,et al.Research on the heat transfer performance of water in vertical upward smooth tube under near critical pressure[J].Journal of Xi’an Jiaotong University,2001,35(1):10-14.
[13]尹飞,陈听宽,罗毓珊,等.亚临界及近临界压力区倾斜管与垂直管中汽水沸腾传热特性比较[J].中国电机工程学报,2005,25(1):137-141.YIN Fei,CHEN Tingkuan,LUO Yushan,et al.Comparison on the boiling heat transfer characteristic of steam-water in the inclined tube and the vertical tube in sub-critical and near critical pressure regions[J].Proceedings of the CSEE,2005,25(1):137-141.
[14]黄锦涛,陈听宽.单相螺旋管圈动态特性研究[J].热能动力工程,1999,14(5):340-342.HUANG Jintao,CHEN Tingkuan.A study of the dynamic characteristics of single phase spiral tube coils[J].Journal of Engineering for Thermal Energy&Power,1999,14(5):340-342.
[15]傅龙泉,马庆,陈金娥.超临界直流锅炉水冷壁动态特性试验研究[J].上海电力学院学报,1995,11(3):9-17.FU Longquan,MA Qing,CHEN Jine.An experimental research into dynamic characteristics of supercritical once-through boiler water wall[J].Journal of Shanghai Institute of Electric Power,1995,11(3):9-17.
[16]宋明强.跨临界自然循环流动不稳定性研究[D].北京:华北电力大学(北京),2016:71-72.
[17]车得福,庄正宁.锅炉[M].2版.西安:西安电子科技大学出版社,2008:413-420.