能源颗粒细度超声法在线测量研究

发布时间：2018-05-20 23:37

本文选题：能源颗粒 + 煤粉细度　；参考：《南京理工大学》2017年硕士论文

【摘要】：细度测量技术在能源、采矿、化工、等领域应用广泛。对于木薯粉、稻壳、煤粉等能源颗粒来说,细度的准确测量在优化燃烧状况、降低污染物排放等方面具有极其重要的作用。目前细度测量主要以离线为主,还没有成熟且精确的细度在线测量方法。本文以燃煤电厂一次风中煤粉细度在线测量研究为背景,探究超声波在线测量的可行性。超声波在工程测量应用中具有非接触、清洁、响应迅速等特点,利用超声波对以煤粉为代表的能源颗粒进行细度测量,具有较好的应用前景。本文围绕能源颗粒细度超声法在线测量研究这一课题,主要开展了以下几个方面的工作:(1)为获得超声衰减系数在不同能源颗粒粒径、超声波频率以及固相浓度下的大小,根据现有的理论模型,对超声波在煤粉-空气两相流中的衰减特性进行数值模拟,得到理想工况下不同超声波频率、颗粒粒径以及固相体积浓度下对超声波衰减系数的影响。(2)为测得真实条件下气固两相流中衰减系数,设计并搭建超声衰减法细度测量试验系统,用玻璃微珠代替煤粉进行超声波衰减特性实验。测量得到不同颗粒粒径、不同超声波频率和不同固相浓度下的声衰减系数,并与理论值进行比较。(3)根据实验结果对现有理论模型进行修正,用等表面积球当量直径代替等体积球当量直径,使模型更接近真实环境的情况,并探讨了修正系数以及颗粒比表面积对超声波衰减系数的影响。在50～120μm粒径区间内,40KHz和100KHz声衰减系数随粒径变化明显,且反演得到的拟合曲线与实验数据吻合程度较好。
[Abstract]:Fineness measurement technology is widely used in energy, mining, chemical and other fields. For energy particles such as cassava powder, rice husk, pulverized coal and other energy particles, the accurate measurement of fineness has an extremely important role in optimizing the combustion status and reducing the emission of pollutants. In this paper, based on the research of on-line measurement of coal fineness in the primary air of coal fired power plant, the feasibility of on-line ultrasonic measurement is explored. Ultrasound has the characteristics of non contact, clean, quick response and so on in the application of engineering measurement. The ultrasonic is used to measure the fineness of energy particles represented by pulverized coal, and it has a good application prospect. This paper focuses on the research on on-line measurement of energy particle fineness ultrasonic method. The following work has been carried out in the following aspects: (1) in order to obtain ultrasonic attenuation coefficient at different energy particle size, ultrasonic frequency and solid concentration, the attenuation of ultrasonic wave in pulverized air two phase flow is based on the existing theoretical model. The effects of different ultrasonic frequencies, particle size and solid volume concentration on ultrasonic attenuation coefficient are obtained under ideal conditions. (2) to measure the attenuation coefficient of gas solid two phase flow under real conditions, the ultrasonic attenuation method is designed and built to reduce the ultrasonic attenuation by using glass beads instead of pulverized coal. Characteristic experiments. The particle size, ultrasonic frequency and sound attenuation coefficient under different solid concentration are measured and compared with the theoretical values. (3) according to the experimental results, the existing theoretical model is corrected and the equivalent diameter of the equivalent surface sphere is replaced by the equivalent diameter of the equal volume ball, which makes the model more close to the real environment and probes into the situation. The effect of the correction coefficient and the surface area of the particle on the attenuation coefficient of ultrasonic wave is discussed. The attenuation coefficient of 40KHz and 100KHz varies with the particle size in the 50~120 m particle size range, and the fitting curve obtained by the inversion is in good agreement with the experimental data.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB559;TM621

【相似文献】