本文選題：煤粉 + 氣固兩相流��； 參考：《華北電力大學(xué)(北京)》2017年碩士論文

【摘要】：燃煤電廠一次風(fēng)管道內(nèi)煤粉顆粒粒度和質(zhì)量流量的在線測量可以為實(shí)時調(diào)節(jié)制粉系統(tǒng)工作參數(shù)提供依據(jù),有助于優(yōu)化制粉系統(tǒng)工作性能、提高煤粉燃燒效率并降低污染物排放。靜電傳感器具有測量特性穩(wěn)定、安裝方便、靈敏度高、維護(hù)需求低和本質(zhì)安全等優(yōu)點(diǎn),已被應(yīng)用于工業(yè)氣固兩相流速度、濃度等重要動態(tài)參數(shù)的測量。本論文首先從理論和實(shí)驗(yàn)兩方面探索了利用靜電傳感器測量煤粉顆粒粒度的可行性,利用有限元仿真軟件COMSOL分析了單個顆粒的粒度對靜電信號強(qiáng)度和頻率的影響。然后根據(jù)靜電法測量原理提出了基于渡越時間的單顆粒粒度測量方法,以及基于顆粒速度變化的多顆粒粒度估測方法。實(shí)驗(yàn)選用石英砂和活性炭兩種不同性質(zhì)的材料在74 mm管徑的氣固兩相流裝置上進(jìn)行,測量裝置使用2mm和10 mm兩種不同軸向?qū)挾鹊撵o電電極。最后通過實(shí)驗(yàn)研究了含水率對靜電法測量顆粒質(zhì)量流量的影響,并改進(jìn)了質(zhì)量流量測量中相關(guān)系數(shù)的標(biāo)定方法。有限元仿真結(jié)果表明當(dāng)顆粒帶電密度相等時可以通過測量靜電信號強(qiáng)度分辨顆粒粒度,當(dāng)顆粒沿環(huán)形靜電傳感器軸向運(yùn)動時其所處的徑向位置對靜電信號頻率造成的影響大于顆粒粒度的影響。實(shí)驗(yàn)結(jié)果表明顆粒粒度會影響靜電信號的強(qiáng)度和主頻,當(dāng)氣力輸送管道內(nèi)風(fēng)速一定時顆粒速度隨其粒度增大而減小,因此可以通過顆粒速度變化推測顆粒粒度。同等條件下顆粒含水率不同,靜電傳感器對顆粒質(zhì)量流量測量結(jié)果不同,針對不同含水率條件標(biāo)定質(zhì)量流量測量系數(shù)可以有效提高測量的準(zhǔn)確性。
[Abstract]:On-line measurement of pulverized coal particle size and mass flow in primary air pipe of coal-fired power plant can provide basis for real-time adjusting the working parameters of pulverizing system, help to optimize the working performance of pulverizing system, improve the efficiency of pulverized coal combustion and reduce pollutant emission. Electrostatic sensor has the advantages of stable measurement characteristics, convenient installation, high sensitivity, low maintenance requirement and essential safety. It has been applied to the measurement of important dynamic parameters such as velocity and concentration of gas-solid two-phase flow in industry. In this paper, the feasibility of using electrostatic sensor to measure particle size of pulverized coal is explored in theory and experiment, and the influence of particle size of single particle on the intensity and frequency of electrostatic signal is analyzed by using finite element simulation software COMSOL. Then, according to the principle of electrostatic measurement, a single particle size measurement method based on transit time and a multi-particle particle size estimation method based on the variation of particle velocity are proposed. Two kinds of materials with different properties, quartz sand and activated carbon, were used in the gas-solid two-phase flow device with the diameter of 74 mm tube. The measuring apparatus used two kinds of electrostatic electrodes with different axial width of 2mm and 10mm. Finally, the effect of water content on particle mass flow is studied by experiments, and the calibration method of correlation coefficient in mass flow measurement is improved. The finite element simulation results show that the particle size can be resolved by measuring the electrostatic signal strength when the charged density of particles is equal. When the particle moves along the axial direction of the ring electrostatic sensor, the influence of the radial position on the frequency of the electrostatic signal is greater than that of the particle size. The experimental results show that the particle size will affect the intensity and frequency of electrostatic signal, and the particle velocity decreases with the increase of particle size when the wind velocity in the pneumatic conveying pipeline is fixed, so the particle size can be estimated by the change of particle velocity. Under the same conditions, the measurement results of particle mass flow rate by electrostatic sensor are different, and the accuracy of measurement can be effectively improved by calibrating the mass flow measurement coefficient according to different water content conditions.
【學(xué)位授予單位】：華北電力大學(xué)(北京)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TP212

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