【摘要】：電力能源產(chǎn)業(yè)是中國重要的能源產(chǎn)業(yè),其中火力發(fā)電占70%以上。在火力發(fā)電系統(tǒng)中占有重要地位的汽輪機(jī)仍然存在諸多問題。汽輪機(jī)末級蒸汽濕度的存在不但降低汽輪機(jī)組的運(yùn)行效率,而且會引起嚴(yán)重的水蝕,給汽輪機(jī)組的安全性與經(jīng)濟(jì)性帶來很大的危害。因此,對蒸汽濕度的測量有重要的理論和實(shí)際意義。為此,本文提出一種以光散射理論為基礎(chǔ)的在線實(shí)時(shí)測量濕蒸汽的方法并進(jìn)行了相關(guān)實(shí)驗(yàn)研究。(1)首先,分析了汽輪機(jī)內(nèi)蒸汽濕度對汽輪機(jī)效率的影響,介紹了國內(nèi)外蒸汽濕度的測量方法；研究了光的散射理論,光經(jīng)過顆粒發(fā)生散射,散射光信號攜帶著散射顆粒的很多信息；研究了球形粒子的Mie散射模型,結(jié)合Lambert-Beer定律,得到了蒸汽濕度與散射光的函數(shù)關(guān)系；對比了前向散射與后向散射的區(qū)別,得到了更優(yōu)的后向散射測量理論。(2)然后,設(shè)計(jì)了后向散射測量模型,搭建了模擬實(shí)驗(yàn)臺,并介紹了其工作原理。該實(shí)驗(yàn)系統(tǒng)由兩部分組成：濕蒸汽發(fā)生部分和濕蒸汽測量部分。濕蒸汽發(fā)生裝置部分包括電熱鍋爐、模擬濕蒸汽氣缸；濕蒸汽測量部分主要包括CCD相機(jī)、激光器、透鏡、光功率計(jì)及光學(xué)鏡片。介紹了CCD相機(jī)工作原理,利用CCD作光學(xué)功率面陣接收器來接收散射光強(qiáng),推導(dǎo)了蒸汽濕度求解的計(jì)算方法,并以此為基礎(chǔ)設(shè)計(jì)了后向散射測量實(shí)驗(yàn)方案,(3)最后,根據(jù)后向散射測量實(shí)驗(yàn)方案,在模擬實(shí)驗(yàn)臺上進(jìn)行了多組實(shí)驗(yàn)。設(shè)定不同的入射光強(qiáng),不同的接收散射角度,不同的截面位置以及不同的工況參數(shù)進(jìn)行實(shí)驗(yàn)測量,得到了散射光強(qiáng)分布的圖像。結(jié)果表明隨著后向散射角度增大散射光強(qiáng)逐漸減弱,后向300時(shí)散射光強(qiáng)較強(qiáng),散射圖像較清晰；隨著入射光強(qiáng)增強(qiáng),散射光強(qiáng)圖像顯著增強(qiáng),入射光在20mmw左右時(shí)產(chǎn)生的測量誤差較��；在濕蒸汽發(fā)生器內(nèi)中間位置略偏向濕蒸汽進(jìn)口的位置是測量的最佳位置,此時(shí)散射圖像清晰,散射光強(qiáng)較強(qiáng),實(shí)驗(yàn)測得濕蒸汽在某種工況下水滴質(zhì)量半徑約為0.96umm,濕度1.1%,證明此激光后向散射法測量濕蒸汽特性的系統(tǒng)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.
【學(xué)位授予單位】：長沙理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TM621;TK267

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相關(guān)期刊論文 前1條

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本文編號：2356712