【作者】 高文星；

【导师】 董凌燕； 陈登福；

【作者基本信息】 重庆大学 ， 冶金工程， 2008， 硕士

【摘要】 在连铸生产过程中,高温铸坯表面温度辐射测量方法的准确性常常由于受到水蒸气、水雾、水膜等参与性介质的辐射特性的影响而大大降低。这是连铸二冷区和轧钢工艺等现代冶金生产设备中常遇到的、且亟待解决的问题。本文从辐射、吸收、散射性介质的辐射特性机理出发研究了水蒸气、水雾和水膜参与性介质对辐射测温准确性影响。并联系济钢4#连铸机的实际生产,设计了铸坯矫直区在线测温系统。水蒸气的辐射特性具有光谱的选择性。分析了水蒸气辐射特性参数的各种谱带模型及近似处理方法。采用了指数宽谱带模型计算了水蒸气在不同温度和测温距离下的发射率。同时,对水蒸气高温谱线光谱数据库(Hitemp)进行谱带扩展,得到了适用于连铸二冷区的水蒸气窄谱带模型参数数据库(包括平均吸收系数κη、谱线平均密度1/ d、平均半宽bL )。利用建立起的数据库参数和单色、比色测温计测温原理模拟计算和比较分析了各工作波长下测温计的测温误差。结果表明,在高温饱和水蒸气的连铸二冷环境中,宜采用1.0μm,1.6μm范围附近的单色测温计。其工作波长能够避开水蒸气吸收波段,几乎不受水蒸气影响。或者通过数据库查寻波段发射率相近的比色测温计进行测温并对结果进行修正。基于Mie散射理论,建立了水雾粒子的消光模型,分析了水雾粒子的散射特性,计算了水雾粒子在各粒径、各波长的消光特性。结果表明,水雾粒子为具有非灰性、参与性特点的弥散系。粒子呈现为连续消光和强烈前向异性散射特性。对单色、比色以及全辐射的红外测温方法的准确性均有影响。水雾的粒径分布、水雾浓度和红外测温仪的工作波长是影响红外测温准确性的主要因素。求解获得了水雾粒子系的衰减系数、散射系数、相函数等参数,为求解辐射传递方程提供必要条件。应用数值计算的方法拟合水膜在各波长下的吸收系数,得到了水膜的透射率的公式组和不同波长、厚度下水膜透射率。研究了水膜时对单色和双色红外辐射温度计示值的测温误差。选择小于1.1μm工作波段的测温仪进行测量二冷铸坯表面存在水膜的铸坯表面温度测量并进行修正。在济钢4#连铸机的矫直区建立了在线测温系统。为二冷配水优化提供数据依据。更多还原

【Abstract】 The surface temperature of continuous casting slab is am important parameter of production control, but its value can’t be measured accurately for the execrable environment at the secondary cooling zone. Under conditions of the secondary cooling zone of continuous casting, the accuracy of surface temperature measurement of high temperature casting slab is frequently and greatly reduced by radiation characteristic of the water vapor, spray, water film and other participational media. This is the porblem that appears in secondary cooling zone of continuous casting and rolling mill which are modern metallurgy production units. Based on the theory and mechanism of radiation, absorption, scattering radiation characteristics of the participational media, this article studied the radiation characteristics of water vapor, spray and water film and the infection to temperature measurement of high temperature casting slab. Designed the on-line temperature measurement system of straightening section of casting slab for 4# CCM of Jinan Iron & Steel Group Corporation.The characteristic of water vapor is spectra selectivity. Generally described different kinds of spectral band model and approximate treatment for parameter of radiation characteristic. Studied the Edwards Indices broadband model and narrow spectrum band model.With the indices broad band model, calculated the emissivity at different temperatures and distances. At the same time, based on the high-temperature spectra line spectrum database (Hitemp), got the parameter database of narrow spectrum band model of water vapor. With these parameters and the principle of monochrome thermometers, Colorimetric Thermometer, calculated the errors under each operating wavelength. Pointed out that in the high temperature environment full of moist steam. It’s suitable using thermodetector operating wavelength bound around 1.6μm, 1.0μm It can avoid the water vapor spectral absorption wave band, They are almost“translucent”, nearly no influence. Or looks up the database to look for water vapor wave length its monochromatic emissivity for the amendment of Colorimetric Thermometer temperature measurement.This paper is based on Mie scattering theory, seted up the extinction model of the water spray particles at second cooling zone , analyzed the scattering properties , computed the extinction characteristic in various particle sizes and radiation wavelengths . It indicated the water spray particles were nongray, participant dissemination system. Under each grain-size distribution, it possessed intensely forward scattering properties and consecutively extinctive characteristic. It have influence on accuracy of both single and colorimetric thermometer temperature measurement. By theoretical analysis we got that: the spray particle size distribution and opreating wavelength is important attribute to its extinction characteristic. Its extinction increased with increasing of particle size. In the service wave band of infrared thermoscope, size distribution is the direct factor for extinction influence of water spray particles.Absorption coefficient of water film is only related to wavelength, thickness, with nothing to do with the temperature. Based on massive experimental data from predecessor, used 6 order polynomial to fit absorption coefficient under various wavelengths, obtained transmittance formula group and transmittivity on various wavelength and thickness. Studied errors of monochrome and colorimetric thermometer when there was vater film on the temperature measurement path of rays. Suggested selecting the service wavelength be shorter than the 1.1μm band for surface temperature measurement. And getting the revision.For 4 # continuous casting machine of Jinan Iron and Steel works, designed the temperature on-line analysis system on straightening section of continuous casting. Supplying water distribution optimization at secondary cooling zone更多还原