光后向散射式烟尘在线测量样机的研制

为弥补传统不透明式烟尘浓度检测仪器的监测及安装的不便,在已设计的一套具有较高灵敏度的利用光后向散射法测烟尘浓度的装置基础上,结合单片机、计算机研制了一套价格比较低廉、易安装且灵敏度较高的能实时在线测量烟尘浓度的测量样机。实验结果证明该样机对粒径范围在几百nm到几μm的烟尘颗粒具有较好的测试性能。     

工业烟气连续排放监测系统

介绍一种可应用于燃煤电厂等工业烟气连续排放的监测系统及其组成,该系统是以工业PC为主控单元、以亚当模块为数据采集与控制器而构建的集散式测控系统,可在线监测工业烟气中SO2浓度、烟尘浓度、含氧量和烟气温度、烟气静压及烟气流速,并可积算烟气中SO2的排放总量,所有监测参数均可实时显示并可通过internet传至当地环保监测中心.     

基于组态王的燃煤电厂超低排放颗粒物浓度监测系统

为解决燃煤电厂超低排放颗粒物浓度监测中存在的集成度低、标定繁琐、不便远程管理等问题,提出了一种基于组态王的颗粒物浓度监测系统。系统融合激光散射法及β射线法,通过PLC实现数据采集与运动控制,采用组态王软件作为上位机开发颗粒物浓度远程监控及Web发布功能。研究结果表明,该监控系统可以远程实时监测和记录颗粒物浓度变化,并适时对监测数据进行校准,提高了监测效率及系统适应性,可以更好地满足燃煤电厂超低排放监管要求。     

基于PLC的等流速在线烟尘采样控制装置设计

针对目前广泛使用的烟尘测量方法普遍存在无法在线连续测量、价格昂贵、效率低下等问题,设计一种基于PLC的等流速在线烟尘采样控制装置,该装置使用PLC和WINCC上位机对采样数据进行实时处理,并对系统各部分进行实时监控,实现烟尘采样的等速采样要求。装置目前安装于太原第二热电厂,现场应用表明:该装置实现了等速采样控制以及在线监测与无人值守,对于监测各电厂烟尘排放含量具有重要意义。     

燃煤电厂烟尘超低排放技术措施研究

随着时代的发展,人们越来越重视环保问题,各地空气环境质量要想得到有效改善,就要确保燃煤电厂的超低排放技术能够实现准确测量,对其日常运行进行优化。目前烟尘超低排放技术主要分为静电除尘技术与深度除尘技术。本文针对燃煤电厂烟尘超低排放技术措施进行了探讨。     

基于STM32的光散射式扬尘在线监测仪

为了实现对扬尘质量浓度在线监测并且实时反馈颗粒物质量浓度值、采样流量和周围环境温湿度等信息,设计了基于STM32微控制器的光散射式扬尘监测仪。通过测量前向散射光反演颗粒物质量浓度,集成了温湿度传感器降低环境湿度干扰。仪器设计紧凑、质量轻、成本低。实验室结果表明该仪器与国外同类型仪器对比的统计相关性较高,相关系数可达到0.95以上,通过外场实验与β射线法对比,相关系数为0.78,测量误差低,可实现对扬尘准确的测量。     

一种新型激光粉尘浓度在线测量仪的研究

本文提出了一种基于光散射原理的粉尘浓度激光测量新方法，该方法无需预先获取粉尘颗粒的平均粒径，可直接测量浓度。基于新方法设计了一套粉尘浓度在线测量仪，测量仪以8031单片机为核心，具有浓度的实时LED显示和数模输出功能，并通过与上位机的串行通信实现浓度数据的后台存储。该仪器具有新颖的光学构造，可在单片机的控制下进行在线标定和在线光路对中，并已用于某钢厂粉尘排放的实时测量，测量结果表明仪器具有良好的灵敏度和可靠性，可满足实时在线测量粉尘浓度的要求。     

烟气分析仪在线监测工业锅炉运行状况

使用烟气分析仪对燃煤锅炉实际运行工况进行了在线监测。利用监测数据比较了锅炉系统技术改造前后的运行状况。结果表明,技术改造取得了令人满意的效果。烟气温度、烟尘和SO2排放浓度降低,锅炉用煤量减少,污染排放达到国家标准,锅炉整体运行效率提高。     

基于后向光散射的颗粒测量技术研究

颗粒粒径和颗粒折射率是光散射颗粒测量技术中的重要参数。为了实现颗粒粒径的测量及其分档,在广义Mie理论基础上,分析了颗粒粒径及折射率对后向散射光能分布的影响,并得到了后向散射光能分布随颗粒粒径及折射率呈周期变化规律。实验验证结果表明,后向散射光能与颗粒粒径及颗粒浓度有关。研究结果可为后续的颗粒测量研究提供参考。     

污染源烟气汞监测EPA30B方法研究及对比应用

我国是一个产煤大国,而且由于我国燃煤技术普遍落后,燃煤释放的汞对环境生态系统的污染更为严重,因此对烟气重金属汞的排放监测是很重要的。烟气汞排放的的测量主要有湿化学分析法、干法吸附剂法和在线分析法。目前部分电厂已经安装上汞在线监测设备,如何对现场设备进行质量和运行验收,国家尚没有出台相关标准。本文在介绍当前汞监测的主要方法的基础上,重点介绍了EPA30B质控方法并与现场在线设备进行比对测试,应用过程中发现了若干问题,并针对这些问题提出了一定的解决方案,相信可以为用户或监测站做类似测试提供帮助。     

基于卡尔曼滤波的烟气NOx浓度融合测量方法

烟气中NO_x浓度的快速准确测量对提高燃煤电厂脱硝系统效率、降低氮氧化物排放具有十分重要作用。针对目前燃煤电厂烟气连续监测系统（Continuous emission monitoring systems,CEMS） NO_x浓度测量存在较大滞后和采样管路吹扫过程中无法进行有效测量等问题,结合CEMS测量和软测量技术各自的特点,提出基于卡尔曼滤波与数据融合技术的NO_x浓度测量方法。阐述了基于卡尔曼滤波的烟气NO_x浓度融合测量方法的原理和特点,并利用燃煤电厂的历史数据对该方法进行了验证。结果表明：通过合理地选择融合测量参数,基于卡尔曼滤波的数据融合测量方法能有效克服CEMS测量滞后问题,并具有较快的测量响应速度和较高的测量精度。当CEMS测量失效时,融合测量依然能够根据软测量值对NO_x浓度进行估计,提高了NO_x浓度测量系统的可靠性。     

基于手持设备的烟尘浓度监测软件设计

烟尘浓度是大气环境质量监测的一项重要指标,本文介绍了一种检测烟尘浓度的常用方法 -光散射法,设计了一种基于ARM嵌入式设备的烟尘浓度在线监测系统,完全可以通过搭载Android系统的智能手机来实时监测烟尘浓度,相比传统的人工监测,它具有更大的移动性、便捷性。本文主要讨论了监测系统的软件部分设计,首先利用无线网络接收传感器采集到的数据,然后进行分析计算并在手持设备上存储和绘制动态曲线,这种方法比起传统的有线连接的监测设备更加灵活。     

Explosion characteristics of combustible wood dust in confined system: Analysis using oxygen consumption energy

The explosion characteristics, such as maximum explosion pressure, rate of explosion pressure rise, explosion efficiency, were investigated to determine the roll and significance of oxygen consumption energy in dust explosion. Dust explosion experiments were conducted in a Siwek 20L spherical explosion apparatus for three wood dust samples from a wood-based panel production factory. Unlike gas explosions having maximum explosion pressure at near chemical stoichiometric concentration, both the maximum explosion pressure and the maximum rate of explosion pressure of wood dusts appeared at three times or much higher equivalence ratio. Although there were differences in particle size among tested dusts, in the case of dust of which the mean particle size was not larger than 100 µm, P_max appeared at lower equivalent ratios when mean particle sizes were smaller and at higher equivalent ratios when mean particle sizes were relatively larger. Explosion efficiency for all dusts are around 10 %, of which the value is relatively lower than most of other normal combustion, which signifies dust explosion remains 90 % of unburned dust with high fire risks after explosion. In a dust explosion, it is difficult to estimate the weight of suspended dust participating in explosions, especially in fuel rich conditions, so a method for estimating explosion overpressure by applying oxygen consumption energy based on unit volume (1 m³, SAPT condition) was newly proposed and verified from the result of explosion efficiency. To practically apply these results to dust treating industry, the assessment procedure for dust explosion influence has been provided by introducing TNT equivalent model and its scaled distance.

     

A Single Particle Photometric Detector For Steric Field-Flow Fractionation

ABSTRACT

A single particle photometric detector is described for use with steric field-flow fractionation. By counting individual particles, the detector circumvents the difficult problem of calibrating detector response for particulate systems. The system is based on the detection of light from a He-Ne laser scattered by particles flowing through a thin flow cell. It was designed for monitoring particles in the 1-70 μm size range. The flow cell, which is easily constructed, has a total volume of 4.6 μl and an optical viewing volume of only 2.8 x 10^-3 μl. A low power compound microscope is a major component of the system. The performance characteristics of the detector are determined by using polystyrene latex beads of different diameters carried through the cell at different flow rates. Measurements are reported for relative signal response as a function of particle diameter, cell time constant as it depends on flow rate, and particle count in relationship to particle concentration. Examples of the detector's response are shown.     

基于蒙特卡罗模型的高浓度浆液细度在线测量

近年来颗粒粒径测量问题受到了国内外的广泛研究。 针对燃煤电厂高浓度脱硫石灰石浆液细度在线测量,将基于蒙特 卡罗方法的声衰减模型拓展至高浓度范围,高浓度蒙特卡罗模型(HC-MCM)预测衰减系数与实验测量值相吻合。 构建 HC-MCM 矩阵用于颗粒粒径分布的反演可减小计算时间,且差分进化算法的计算结果与设定粒径和分布宽度的相对误差小于 1% 。 搭建基于透射和反射法的双模式超声检测装置并开发软件测量系统,加工适用于高浓度浆液细度测量的透射传感器和超声探 针,依托燃煤电厂完成长达 168 h 的浆液细度在线测量实验。 结果表明,两种模式超声衰减谱的变化趋势和数值大小基本吻 合。 粒径分布参数 DV50 与激光粒度仪测量结果的相对误差小于 8% ,其粒径分布满足燃煤电厂成品石灰石浆液的细度要求。     

High resistivity characteristics of the sinter dust generated from the steel plant

The electrical resistivity of sinter dusts generated from the steel industry and coal fly ash from the coal power plant has been investigated using the high voltage conductivity cell based on JIS B 9915 as a function of temperature and water content. Dust characterization such as the chemical composition, size distribution, atomic concentration, and surface structure has been conducted. Major constituents of sinter dusts were Fe₂O₃ (40–74.5%), CaO (6.4–8.2%), SiO₂ (4.1–6.0%), and unburned carbon (7.0–14.7%), while the coal fly ash consisted of mainly SiO₂ (51.4%), AI₂O₃ (24.1%), and Fe₂O₃ (10.5%). Size distributions of the sinter dusts were bi-modal in shape and the mass median diameters (MMD) were in the range of 24.7–137μm, whereas the coal fly ash also displayed bi-modal distribution and the MMD of the coal fly ash was 35.71 μm. Factors affecting resistivity of dusts were chemical composition, moisture content, particle size, gas temperature, and surface structure of dust. The resistivity of sinter dusts was so high as 10¹⁵ ohm cm at 150 °C that sinter dust would not precipitate well. The resistivity of the coal fly ash was measured 1012 ohm cm at about 150 °C. Increased water contents of the ambient air lowered the dust resistivity because current conduction was more activated for absorption of water vapor on the surface layer of the dust.     

烟尘浓度自动检测仪的研制

烟尘浓度检测是环境监测的一项重要内容。本文介绍一种以８０３１单片机为核心，采用光散射法测定烟尘浓度的自动检测系统，为高浓度烟尘及其它粉尘的测量提供一种有效的检测手段。本系统可作为环保部门的执法工具。     

激光透射式粉尘仪的微弱信号处理研究

为实现在线监测粉尘浓度,设计了一个激光在线粉尘检测仪.在一个典型的烟尘排放连续监测(CEMS)系统中,激光粉尘检测距离要求达到15m以上,然而半导体激光器的输出光功率在20 mW以下.为了从强噪声背景中提取极其微弱的反射光信号,设计了一种数字平均器以提取“nW”级别的微弱反射光信号.对原型机在不同测量距离和消光比条件下...     

Acoustic emissions for particle sizing of powders through signal processing techniques

The present work introduces an innovative method for measuring particle size distribution of an airborne powder, based on the application of signal processing techniques to the acoustic emission signals produced by the impacts of the powder with specific metallic surfaces. The basic idea of the proposed methodology lies on the identification of the unknown relation between the acquired acoustic emission signals and the powder particle size distribution, by means of a multi-step procedure. In the first step, wavelet packet decomposition is used to extract useful features from the acoustic emission signals; the dimensionality of feature space is further reduced through multivariate data analysis techniques. As a final step, a neural network is properly trained to map the feature vector into the particle size distribution.The proposed solution has several advantages, such as low cost and low invasiveness which allow the system based on this technique to be easily integrated in pre-existing plants. It has been successfully applied to the PSD measurement of coal powder produced by grinding mills in a coal-fired power station, and the experimental results are reported in the paper. The measurement principle can also be applied to different particle sizing applications, whenever a solid powder is carried in air or in other gases.     

基于光后向散射法的测尘仪的应用研究与设计

针对国家环保总局提出的有效监测和控制烟尘排放的要求,设计以光后向散射法为原理的烟尘检测仪.介绍系统的原理和构成,及其安装与校准.系统不仅可以实时、在线和连续测量,而且现场安装简便.经过现场测试研究证明:系统的灵敏度高,精确度高,可靠性好,其线性回归方程的相关系数达到0.99,为该领城的研究人员提供了实践依据.