光后向散射式蒸汽湿度测量方法的实验研究
发布时间：2018-11-25 16:10
【摘要】：电力能源产业是中国重要的能源产业,其中火力发电占70%以上。在火力发电系统中占有重要地位的汽轮机仍然存在诸多问题。汽轮机末级蒸汽湿度的存在不但降低汽轮机组的运行效率,而且会引起严重的水蚀,给汽轮机组的安全性与经济性带来很大的危害。因此,对蒸汽湿度的测量有重要的理论和实际意义。为此,本文提出一种以光散射理论为基础的在线实时测量湿蒸汽的方法并进行了相关实验研究。(1)首先,分析了汽轮机内蒸汽湿度对汽轮机效率的影响,介绍了国内外蒸汽湿度的测量方法；研究了光的散射理论,光经过颗粒发生散射,散射光信号携带着散射颗粒的很多信息；研究了球形粒子的Mie散射模型,结合Lambert-Beer定律,得到了蒸汽湿度与散射光的函数关系；对比了前向散射与后向散射的区别,得到了更优的后向散射测量理论。(2)然后,设计了后向散射测量模型,搭建了模拟实验台,并介绍了其工作原理。该实验系统由两部分组成：湿蒸汽发生部分和湿蒸汽测量部分。湿蒸汽发生装置部分包括电热锅炉、模拟湿蒸汽气缸；湿蒸汽测量部分主要包括CCD相机、激光器、透镜、光功率计及光学镜片。介绍了CCD相机工作原理,利用CCD作光学功率面阵接收器来接收散射光强,推导了蒸汽湿度求解的计算方法,并以此为基础设计了后向散射测量实验方案,(3)最后,根据后向散射测量实验方案,在模拟实验台上进行了多组实验。设定不同的入射光强,不同的接收散射角度,不同的截面位置以及不同的工况参数进行实验测量,得到了散射光强分布的图像。结果表明随着后向散射角度增大散射光强逐渐减弱,后向300时散射光强较强,散射图像较清晰；随着入射光强增强,散射光强图像显著增强,入射光在20mmw左右时产生的测量误差较小；在湿蒸汽发生器内中间位置略偏向湿蒸汽进口的位置是测量的最佳位置,此时散射图像清晰,散射光强较强,实验测得湿蒸汽在某种工况下水滴质量半径约为0.96umm,湿度1.1%,证明此激光后向散射法测量湿蒸汽特性的系统具有可行性。
[Abstract]:Power energy industry is an important energy industry in China, in which thermal power generation accounts for more than 70%. Steam turbines, which play an important role in thermal power generation systems, still have many problems. The existence of steam humidity in the last stage of steam turbine not only reduces the operation efficiency of steam turbine unit, but also causes serious water erosion, which brings great harm to the safety and economy of steam turbine unit. Therefore, the measurement of steam humidity has important theoretical and practical significance. In this paper, a method of on-line and real-time measurement of wet steam based on the theory of light scattering is proposed, and related experiments are carried out. (1) first, the effect of steam humidity on steam turbine efficiency is analyzed. The measurement methods of steam humidity at home and abroad are introduced. The scattering theory of light is studied, the scattering light signal carries a lot of information of scattering particles, the Mie scattering model of spherical particles is studied, and the function relationship between vapor humidity and scattered light is obtained by combining Lambert-Beer 's law. The difference between forward scattering and backward scattering is compared, and a better theory of backscattering measurement is obtained. (2) then, a backscattering measurement model is designed, a simulation test bench is built, and its working principle is introduced. The experimental system consists of two parts: the wet steam generating part and the wet steam measuring part. The wet steam generator includes an electrically heated boiler, a simulated wet steam cylinder, and a wet steam measuring unit including a CCD camera, a laser, a lens, an optical power meter and an optical lens. This paper introduces the working principle of CCD camera, uses CCD as optical power array receiver to receive scattered light intensity, deduces the calculation method of steam humidity, and designs the experimental scheme of backscattering measurement based on this. (3) finally, According to the scheme of backscattering measurement, many groups of experiments were carried out on the simulation bench. By setting different incident light intensity, different receiving scattering angle, different cross section position and different operating condition parameters, the image of scattering intensity distribution is obtained. The results show that the scattering intensity decreases gradually with the increase of the backscattering angle, and the scattering light intensity is stronger and the scattering image is clear when the backscatter angle is 300. With the enhancement of the incident light intensity, the scattered light intensity image is enhanced significantly, and the measurement error of the incident light is smaller when the incident light is about 20mmw. The position in the middle of the wet steam generator is slightly biased to the inlet position of the wet steam. The scattering image is clear and the scattering light intensity is strong. The experimental results show that the mass radius of the wet steam droplet is about 0.96 umm under a certain working condition. The humidity is 1.1, which proves the feasibility of the system for measuring the characteristics of wet steam by laser backscattering.
【学位授予单位】：长沙理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM621;TK267
本文编号：2356712
[Abstract]:Power energy industry is an important energy industry in China, in which thermal power generation accounts for more than 70%. Steam turbines, which play an important role in thermal power generation systems, still have many problems. The existence of steam humidity in the last stage of steam turbine not only reduces the operation efficiency of steam turbine unit, but also causes serious water erosion, which brings great harm to the safety and economy of steam turbine unit. Therefore, the measurement of steam humidity has important theoretical and practical significance. In this paper, a method of on-line and real-time measurement of wet steam based on the theory of light scattering is proposed, and related experiments are carried out. (1) first, the effect of steam humidity on steam turbine efficiency is analyzed. The measurement methods of steam humidity at home and abroad are introduced. The scattering theory of light is studied, the scattering light signal carries a lot of information of scattering particles, the Mie scattering model of spherical particles is studied, and the function relationship between vapor humidity and scattered light is obtained by combining Lambert-Beer 's law. The difference between forward scattering and backward scattering is compared, and a better theory of backscattering measurement is obtained. (2) then, a backscattering measurement model is designed, a simulation test bench is built, and its working principle is introduced. The experimental system consists of two parts: the wet steam generating part and the wet steam measuring part. The wet steam generator includes an electrically heated boiler, a simulated wet steam cylinder, and a wet steam measuring unit including a CCD camera, a laser, a lens, an optical power meter and an optical lens. This paper introduces the working principle of CCD camera, uses CCD as optical power array receiver to receive scattered light intensity, deduces the calculation method of steam humidity, and designs the experimental scheme of backscattering measurement based on this. (3) finally, According to the scheme of backscattering measurement, many groups of experiments were carried out on the simulation bench. By setting different incident light intensity, different receiving scattering angle, different cross section position and different operating condition parameters, the image of scattering intensity distribution is obtained. The results show that the scattering intensity decreases gradually with the increase of the backscattering angle, and the scattering light intensity is stronger and the scattering image is clear when the backscatter angle is 300. With the enhancement of the incident light intensity, the scattered light intensity image is enhanced significantly, and the measurement error of the incident light is smaller when the incident light is about 20mmw. The position in the middle of the wet steam generator is slightly biased to the inlet position of the wet steam. The scattering image is clear and the scattering light intensity is strong. The experimental results show that the mass radius of the wet steam droplet is about 0.96 umm under a certain working condition. The humidity is 1.1, which proves the feasibility of the system for measuring the characteristics of wet steam by laser backscattering.
【学位授予单位】：长沙理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM621;TK267
【参考文献】
相关期刊论文 前1条
1 黄宗升,秦石乔,王省书;探测器点阵法测量激光光斑参数的仿真[J];强激光与粒子束;2005年03期
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