【正文】 ons [13].. The auxiliary values consideredThe following values were introduced: emissivity of the walls ()。 mass of ?ue gases produced under a stoichiometric reaction per unit of mass of fuel (Mfumes = kg/kg) and density of the gas expressed under normal conditions (qgNC = kg/m3).4. Model studyThe model includes parameters that were presented in a panion paper [1]. The values of these parameters are estimated in a ?rst stage。 surface of the walls,including the ?ctitious surfaces of the inlet and the outlet (total = 745 m2)。 1:64435 kg=s and external surroundings temperature T1 = 293 K. For the tubes of the roof, we considered: dry saturated steam at a temperature of Ti,v = K, the mass ?ow rate in each tube _ mv 188。參考文獻(xiàn) 1．葉濤. 熱力發(fā)電廠[M] ， 北京：中國(guó)電力出版社， 2．黃興元. 熱力發(fā)電廠課程設(shè)計(jì)[M]，北京：中國(guó)電力出版社，3．葉江明. 電廠鍋爐原理及設(shè)備[M]， 北京：中國(guó)電力出版社 ，2006 4．王毅林. 電廠汽輪機(jī)原理及設(shè)備[M] ， 北京：中國(guó)電力出版社，2006 5．中華人民共和國(guó)家經(jīng)濟(jì)貿(mào)易委員會(huì). 火力發(fā)電廠設(shè)計(jì)技術(shù)規(guī)程[M]， 北京：中國(guó)電力出版社DL50002000，19946．中華人民共和國(guó)家經(jīng)濟(jì)貿(mào)易委員會(huì). 火力發(fā)電廠汽水管道設(shè)計(jì)技術(shù)規(guī)定[M] ， 北京：中國(guó)電力出版社 DLT5054，1996 7．中華人民共和國(guó)家經(jīng)濟(jì)貿(mào)易委員會(huì). 火電廠汽水管道零件及部件典型設(shè)計(jì)[M],北京電力出版社，2000版英文文獻(xiàn)原文：Application of a thermal model to a power plant reheater with irregular tube temperaturesAbstract:A threedimensional thermal model for the reheater of a utility boiler is applied to a 350 MWe power plant. The model permits the consideration of nonuniform steam ?ow inside the tubes, which can lead to excessive temperature and hence thermal stress in a part of these. Parametric calculations are performed to examine the in?uence of various empirical coe?cients included in the model. Experimental online and o?line data will be obtained and will be introduced as boundary conditions or used to validate the model. The steam ?ow distribution inside the tubes will be considered uniform or nonuniform depending on the tube serpentine of the reheater. The results predicted by the model of the temperature of the tubes at the reheater outlet and the outlet steam temperature are satisfactorily pared with the experimental measurements. Moreover, the results predicted for the temperature of the gases in an intermediate section of the reheater are analysed and pared with the experimental results from o?line measurements.Keywords:Reheater,Power plant boiler,Model,Steam tubes temperature,Gas measurement1. Introduction：The operational conditions, fuel employed and the tube material of power plant ponents subjected to high pressures and temperatures are essential to determine the remaining life, availability and e?ciency of the , special attention needs to be paid to such critical ponents as the superheater and reheater heat exchangers, headers, and main and reheated steam lines. The principal mechanisms that cause tube failure have been summarized in [1] and techniques for assessing working life and their application to practical cases are being employed more and more. This assessment may be carried out during maintenance inspections [2,3] or online by means of the analysis of operation variables [4,5]. At the same time, e?orts are being made to avoid, as far as possible (design or operational), conditions that can lead to thermal stress of the tubes or overexposure to high temperatures [6,7].A reheater at a 350 MWe thermal power plant has suffered problems of thickness losses and repeated tube ?ssures, the defects being located in both the straight and curved tubes. The material of some of the tubes in the reheater has been changed in zones where the ?ssures were produced or damage was detected in maintenance operations. Nevertheless, the problems still remain and their underlying cause seems to be thermal in nature linked to thermodynamic conditions in the reheater.This paper presents the application of a threedimensional model for a utility boiler reheater which was presented in a panion paper [8]. The model takes into account every serpentine and tube constituting the reheater and performs the coupled simulation of the ?ow and heat transfer in the reheater of the utility boiler, employing the concepts of porosity and e?ective viscosity, along with empirical correlations for the convective and apparent radiative heat transfer coe?cients. The model can be applied to the tube bundle of boiler ponents placed in the convective–radiative zone. However, speci?c restrictions are imposed for calculating the heat transfer convective coe?cients (Reynolds number, tube layout, and dimensionless distances) and the speci?cally applied coe?cients for the radiation model, which are dependent on the type of fuel, volatile matter and burners, etc., in accordance with the bases of the method expounded in [9] and recently cited in [10]. All these restrictions should be checked and the necessary changes made when necessary.In order to apply the model, it is necessary to add boundary and operating conditions. To do so, we shall provide the following experimental values of: (1) the automatically registered variables of the boiler that a?ect the thermal behaviour of the reheater。 汽機(jī)排汽管道選型汽機(jī)排氣采用雙排汽方式，以下選擇單管管型：已知參數(shù)：，根據(jù)《火力發(fā)電廠汽水管道零件及部件典型設(shè)計(jì)2000》選擇標(biāo)準(zhǔn)管道。 低壓加熱器H7相關(guān)抽汽管道選型已知參數(shù)：，根據(jù)《火力發(fā)電廠汽水管道零件及部件典型設(shè)計(jì)2000》選擇標(biāo)準(zhǔn)管道。則選擇管道型號(hào)為：標(biāo)識(shí)編碼： 用途：普通設(shè)計(jì)壓力： 類別：無(wú)縫鋼管技術(shù)規(guī)范： 尺寸規(guī)范： 材質(zhì)：標(biāo)管通徑： 焊接值： 質(zhì)量：用所選管的管徑反計(jì)算最大流量：已知實(shí)際最大流量：裕量滿足需求。則選擇管道型號(hào)為：標(biāo)識(shí)編碼： 用途：再熱蒸汽汽段設(shè)計(jì)壓力： 類別：無(wú)縫鋼管技術(shù)規(guī)范： 尺寸規(guī)范：材質(zhì)：F12(X20CrMoV)標(biāo)管通徑： 外徑壁厚：焊接值： 質(zhì)量：用所選管的管徑反計(jì)算最大流量：已知實(shí)際最大流量：裕量滿足需求。則選擇管道型號(hào)為：標(biāo)識(shí)編碼： 用途：主蒸汽管道設(shè)計(jì)壓力： 類別：無(wú)縫鋼管設(shè)計(jì)溫度： 技術(shù)規(guī)范：ASTM A 335材質(zhì)：A335P91 標(biāo)稱外徑： 最小內(nèi)徑X最小壁厚：焊接值： 質(zhì)量：用所選管的管徑反計(jì)算最大流量： 已知實(shí)際最大流量：裕量滿足需求。確定管徑時(shí)，一般應(yīng)根據(jù)運(yùn)行中介質(zhì)的最大流量和允許的最大壓力損失進(jìn)行計(jì)算，由于管徑和管壁厚度的偏差，計(jì)算時(shí)應(yīng)考慮10%的裕量以及足夠安全系數(shù)。（4）《低壓流體輸送用焊接鋼管》（GB/T3092）及《低壓流體輸送用鍍鋅焊接鋼管》（GB/T3092）中的加厚管子，~200℃的C類流體。 推薦流速表截止類型管道類型推薦流速（m/s）主蒸汽主蒸汽管道： 40—60其他蒸汽抽汽或輔助蒸汽管道：過(guò)熱汽：35—60飽和汽：30—0濕蒸汽：20—35給水高