Dust removal efficiency of high pressure atomization in underground coal mine

To master theoretical calculation for dust removal efficiency of high pressure atomization in an underground coal mine, the corresponding atomization characteristics and dust removal efficiency were both comprehensively studied in theory by virtue of related theories of hydromechanics and aerosol.According to actual measurements of flow coefficients and atomization angles of X-type swirl nozzle,computational formula was derived for atomized particle sizes of such a nozzle in conjunction with relevant empirical equation. Moreover, a mathematical model for applying high pressure atomization to dust removal in underground coal mine was also established to deduce theoretical computation formula of fractional efficiency. Then, Matlab was adopted to portray the relation curve between fractional efficiency and influence factors. In addition, a theoretical formula was also set up for removal efficiency of respirable dust and total coal dust based on dust size and frequency distribution equations. In the end,impacts of dust characteristic parameters on various dust removal efficiencies were analyzed.

Water film area and dust removal efficiency of string grilles:a theoretical analysis

Based onmultiphase flowtheory and capillary mechanics,the dimensionless bond number expression of the influence of string grille wire spacing on droplet spreading is derived.Taking a liquid film formed by spreading droplets based on Kelvin correlation,the Young-Laplace equation,and the Hagen-Poiseuille law,an equation for calculating the thickness and height of the liquid film is established with temperature,relative humidity and molar volume of liquid phase as independent variables.According to the theory of string grille filtration and dust removal,a dust removal efficiency calculation model covering the wet string grille wire group is constructed based on the liquid film thickness,height,wire diameter,water film area,and vortex shedding frequency.Finally,a theoretical analysis of the influence of water film area on the efficiency of wet string grille dust removal is carried out based on the spray pressure and the ratio of string grille wire distance to wire diameter.It is found that the effect of spray pressure on water film area and dust removal efficiency is more significant than the string grille wire distance diameter ratio.Moreover,the optimized combination of wet string grille wire distance diameter ratio 0.84,wind speed 3m/s and spray pressure 0.8 MPa is found,which could provide an important reference for engineering applications.

Numerical Simulation of Dust Removal in the Cyclone Collector of a Straw Crusher Based on a Discrete Phase Model

The cyclone dust collector is an important subsystem of straw crushers used in agriculture.In the present study,a new type of dust collector with involute morphology is proposed to obtain better dust removal efficiency with respect to that of classical tangential and spiral dust collectors.A discrete phase model(DPM)method is used in synergy with a turbulence model,and the SIMPLE algorithm to simulate the flow field inside the dust collector and the related particle dynamics.It is shown that the internal flow field features a primary swirl,a secondary swirl and blockage effects.Moreover,for the involute dust collector,the tangential velocity in the initial stage and the pressure in the high-pressure area are larger than those obtained for the classical types.The dust removal efficiency is 37.11%,25.3%,and 16.37%for the involute type dust collector,the tangential type and the spiral type,respectively.

Further Study of Electric Dust Removal with Transparent Fork Electrodes

This study is a continuation of our previous work. In this experiment, transparent tin-doped indium oxide (ITO) fork electrodes with different width and spacing were coated on the glass substrates. The used dust particle size was smaller than 180 mesh. The effects of the electrode width, the electrode spacing, voltage, frequency, waveform, and the duty ratio on the dust removal efficiency were studied. The obtained optimum conditions of dust removal were as follows: voltage was 1500 V, frequency was 15 Hz, square wave, 10% duty ratio, the electrode width was 0.5 mm, electrodes spacing was 1.3 mm. Our previous experimental results show that the dust removal efficiency would be up to 95%. But in this experiment, under the optimum conditions, the dust removal efficiency could be up to 99%.

Design and Development of a High Efficiency Carbon- Granular Bed Filter in Industrial Scale

The new dust removal technical route using the carbon-granular bed filter, packed of carbon particles with appropriate grade derive from an online-process vibration sieve, to replace the traditional baggy filter had been developed successfully for capturing the micro-carbon dusts produced from pulverization of petroleum coke, and the green close loop of carbon materials is thus completed in the combined pulverizing and classifying system and pulverized carbon dust removal process. The high dust removal efficiency greater than 99%, low outlet dust concentration less than 100mg·m-3, low pressure drop through dust filtration chamber less than 980Pa, simple and easy design, and flexible and stable operation were achieved also with the carbon-granular bed filter in both bench and industrial scale operations.

Enhancement of Cathode Dust Collection and its Application in Improving the Efficiency of Dry Electrostatic Precipitator

As the main equipment of flue gas dedusting in coal fired boiler,electrostatic precipitator(ESP)can meet the requirements of emission standard for air pollutants from coal-fired power plants through improving the efficiency of ESP and combining with desulfurization system while not installing wet ESP(WESP).This paper introduces the modifications of ESP cathode structure to improve the efficiency of dust collection by reducing the secondary dust loss at cathode.The application of cathode dust collection provides a reference for the improvement of ESP dust collection efficiency.

旋风滤布除尘器的除尘性能研究

为了解决传统旋风除尘器对颗粒捕集效率差、袋式除尘器使用寿命短等问题,将传统旋风除尘与滤布除尘有效结合,形成一种优势互补的一体式旋风滤布除尘装置。采用数值模拟和试验相结合的方法,探究在不同出口压力的条件下,旋风滤布除尘器的除尘效率及压力损失情况。利用Fluent软件对旋风滤布除尘器的除尘性能进行模拟,模拟采用雷诺应力模型(Reynolds Stress Model, RSM)和多相流模型(Discrete Phase Model, DPM)。通过搭建试验平台,测试除尘装置的除尘性能,验证数值模拟的可靠性与正确性。结果表明:旋风滤布除尘器的除尘效率相对于旋风除尘有明显的提高,旋风滤布除尘器的除尘效率与出口负压呈正相关,旋风滤布除尘总效率随出口负压的增加而逐渐增加,且旋风滤布除尘器除尘效率的最小值都高于旋风除尘部分除尘效率的最大值;旋风滤布除尘器的压力损失随出口负压的增加而线性增大,压力损失增大使得除尘器损耗的功率也增多,且压力损失的上升速度快于除尘效率的提升速度;在旋风滤布除尘器中,负压增大后,旋风除尘捕获大粒径颗粒,逃逸到滤布部分的颗粒粒径都较小,降低了滤布被大颗粒划破的风险,提高了滤袋的使用寿命。

斜巷转载点粉尘污染规律及多断面雾幕控尘技术研究

针对斜巷转载点粉尘污染严重的问题,运用COMSOL软件对棋盘井煤矿3号转载点进行了几何建模,并基于计算流体力学(CFD)粒子追踪模型、有限元法和k-ε湍流模型,计算了3号转载点风流流线分布、速度多切面分布以及粉尘粒子运动轨迹,研究了生产工作时3号转载点处风流变化及粉尘运移规律,并针对性地提出了一种多断面雾幕控尘技术。该技术基于螺旋雾幕控尘、超音速隔尘原理,可形成距离长、覆盖范围广的雾幕以最大限度包裹粉尘颗粒,实现粉尘高效净化。最后通过控尘试验及在棋盘井煤矿3号转载点现场应用,验证了该技术的高效降尘特性以及可靠性。研究结果表明:风流分布主要受皮带速度、牵引力和诱导气流的综合作用影响,沿水平和垂直方向分层分布,形成密集且平均速度为0.5 m/s的涡流;粉尘易受涡流影响向四周扩散,主要分布在下风侧,粒径为5~15μm更容易受风流牵引扩散,聚集于工人呼吸带高度,污染严重。将该技术进行控尘试验和现场应用后,全尘和呼尘降尘效率分别高达93.65%、85.59%以上。

低阻文丘里振弦栅除尘系统内流场模拟研究

为探究除尘系统流场分布情况以及粉尘与液滴颗粒对除尘系统性能的影响,运用Fluent模拟研究气态单相流、气固两相流和气固液三相流的流场分布情况,分析除尘器在不同工况条件下压力与流场分布规律以及颗粒的运动情况。结果表明:除尘系统流场主要受除尘器结构的影响,受粉尘颗粒的影响较小;液滴颗粒的存在会提高系统的除尘效率;加入液滴颗粒后,粉尘运动凌乱度增强,与液滴碰撞作用加强,促进了细微粉尘的凝聚,但同时会影响除尘器流场稳定性,增加除尘系统阻力损失。

气固逆流式移动床过滤器的实验研究

为探究操作条件对气固逆流式移动床过滤器过滤性能的影响,通过大型冷模实验,考察了气固逆流式移动床过滤器的捕集颗粒循环强度、入口粉尘浓度、表观气速及入口粉尘粒径对装备性能的影响。实验结果表明,表观气速是影响床层压降的主要因素,表现出正相关的趋势。捕集颗粒循环强度、入口粉尘浓度、粉尘粒径的改变对床层压降影响较小。捕集颗粒循环强度和入口粉尘浓度的增加使压降增加。而粉尘粒径与床层压降间的关系随时间变化,开始时粉尘粒径与压降呈正相关,但当装置运行至平稳阶段则趋于降低。装备的除尘效率与入口粉尘浓度及颗粒循环强度正相关,与粉尘粒径及表观气速负相关。但粉尘粒径越小过滤效率越高的趋势受装置内滤饼的影响,仅在粉尘中位粒径10μm以上,且入口粉尘质量浓度在0~32 g·m^(-3)出现。移动床过滤器保持稳定床层压降的同时,具有较高的除尘效率。在颗粒循环强度0.3119 kg·s^(-1),16.5~32.7 g·m^(-3)入口粉尘浓度条件下,除尘效率可达99%;且对细微(13μm以下)粉尘的粒级效率接近99.9%。

煤矿运输复合降尘剂的制备与降尘性能研究

为了降低煤炭资源运输过程中粉尘的污染程度,以烷基糖苷、3-氯-2-羟丙基三甲基氯化铵和助剂A为主要原料,制备了一种适合煤矿运输用的新型复合降尘剂JCS-1,以除尘效率为评价指标对其制备条件进行了优化,并考察了不同质量分数复合降尘剂JCS-1的表面活性、润湿性能和降尘性能。实验结果表明:在反应温度为85℃、反应时间为5 h、助剂A的质量分数为5%的条件下制备的复合降尘剂JCS-1的除尘效率最高;随着复合降尘剂JCS-1质量分数的不断增大,溶液表面张力和其在煤薄片表面的接触角均呈现出逐渐降低的趋势,而除尘效率则呈现出先增大后减小的趋势;当复合降尘剂JCS-1的质量分数为0.05%时,除尘效率可以达到最大(96.6%),降尘效果较好,能够满足煤矿运输过程中降尘作业的需求。

岩巷掘进工作面控风净化除尘系统设计与应用

针对岩巷掘进工作面压风风流携带迎头粉尘弥漫扩散造成粉尘治理难度大的问题,提出了掘进面“控风—净化”综合粉尘治理方案,构建了由湿式旋流除尘器、易装拆控尘装置、便移式负压风筒等组成的岩巷掘进面高效除尘系统,对比分析了除尘系统的不同安装方案对除尘效果的影响;综合考虑现场除尘效果与劳动强度,明确了湿式旋流除尘器最佳安装方案以及负压风筒与控尘装置的最优安装位置。在某矿辅运大巷岩巷掘进面进行了现场应用,结果表明:当负压风筒安装至通风风筒对侧,吸尘口距巷道迎头3 m,控尘装置位于通风风筒压风口后方5 m时,迎头高浓度粉尘在通风风筒压风、控尘装置控风及除尘器抽尘共同作用下被控制在迎头附近,并不断向负压风筒吸尘口运移最终被除尘器抽入净化,除尘器前方全尘和呼尘除尘效率分别达到95.9%和94.9%以上,除尘器后方全尘和呼尘除尘效率分别达到96.5%和95.4%以上,显著提升了巷道可见度,有效解决了岩巷掘进面通风造成的粉尘治理难题。

槽式聚光器镜面高压气流除尘实验研究

太阳能聚光系统的镜面积尘不仅降低了光电转换效率,还缩短了系统的使用寿命。为此,搭建了槽式聚光镜面压缩空气除尘系统。运用扫描电子显微镜、激光粒度分析仪、X射线衍射仪和X射线荧光光谱仪等仪器,对积尘颗粒的晶体结构、尺寸分布、元素种类及其占比进行了分析。通过压缩空气除尘系统研究了风刀喷头的入口压力,镜面倾角,除尘高度对除尘效率的影响。结果表明,直径小于10μm的颗粒在积尘中所占比例超过50%,其中石英和白云母是积尘颗粒中主要的物质成分。积尘颗粒中的元素含量差异显著,氧元素含量最高,其次是硅元素,而氢元素的含量最低。除尘效率随着除尘压力的增加、镜面布置的倾角增大以及风刀喷头的除尘角度和高度减小而提高,最高除尘效率可达98.94%,此时镜面的积尘密度为0.03 g/m^(2),反射率为98.94%。

声波团聚净化尿素造粒塔尾气实验研究

尿素造粒塔大多采用水洗工艺处理尾气粉尘,存在较为严重的细颗粒粉尘溢出和水汽拖尾问题,因此需深入探究声波团聚技术在造粒塔尾气处理方面的应用。通过实验研究了声波与喷雾对除尘效率的影响,发现声波单独作用时在3500 Hz达到最佳除尘效率,为74.49%,协同喷雾时2600 Hz即可实现相近的除尘效率,为73.83%。进一步探究其中机理,采用以粒径测试为依据的团聚效率作为评价指标,结果显示,2600 Hz声波与喷雾单独作用时团聚效率分别为30.37%和28.82%,协同作用时团聚效率大幅提升至57.95%。该研究可为后续造粒塔工程改造提供理论与数据支持。

压电式超声雾化降尘系统设计及其试验研究

通过传送带传送物料是散料工业运输的主要方式,对运输过程中产生的粉尘进行治理是散料工业运输亟需解决的问题,目前应用比较多的方法为雾化降尘法。为了提升雾化降尘的效果,设计了一种30 kHz喇叭型压电式超声雾化装置和配套的雾化降尘试验系统,并采用单因素试验研究入口水流量、风速、粉尘种类、颗粒直径、喷嘴安装角度等工艺参数对雾化降尘效率的影响规律。结果表明,当入口水流量为30 L/h时,对煤粉粉尘降尘效率为75.9%;当风速为2.1 m/s时,对煤粉粉尘降尘效率为61.1%;相比较于煤粉和沙子,黄土的降尘效率略高;该喷嘴对粒径为107~180μm范围内的煤粉粉尘降尘效率最高为73.9%;当喷嘴安装角度为0时,对煤粉粉尘降尘效率最高为81%。

微管束除雾器在火电厂应用试验研究

为了检验微管束除雾器在电厂运行条件下的综合性能,在燃煤发电机组二级脱硫塔的四级管束除雾器旁并联安装了微管束除雾器试验装置,通过对比试验验证微管束除雾器的性能。试验期间微管束除雾器进出口的气流阻力为四级管束除雾器的1/4;尝试采用连续取样管内冷凝水的电导率作为除雾器出口的雾滴浓度的间接指标,微管束除雾器出口约为四级管束除雾器的一半,电荷法颗粒浓度仪测得微管束除雾器出口颗粒物浓度为四级管束除雾器出口的1/10,表明微管束除雾器颗粒物分离性能成倍提升;运行5个月后,微管束除雾器仅在出口附近管壁有少量脏污,导流叶片及周边没有被污染。结果表明,微管束除雾器节能减排优势突出,适合在电厂长期使用。

燃煤电厂袋式除尘器环保与节能耦合的性能优化研究

燃煤电厂袋式除尘系统在进行超低排放的过程中会消耗大量能源,为了使除尘器在满足出口烟气浓度排放指标的情况下以最优能耗的状态运行,收集燃煤电厂运行期间的监测数据,通过对除尘系统中涉及到能量的消耗及组成进行分析,建立单位质量除尘能耗指标模型和除尘效率指标,并研究灰分、燃煤热值和发电机组负荷率对除尘系统的影响规律。结果表明:除尘效率随灰分增加而提高,单位质量除尘能耗随灰分增加而减少并在灰分为18%时获得最佳能耗,燃煤热值的增加会使单位质量除尘能耗整体上升,但除尘系统在高热值区间运行较为稳定,机组负荷率在中高区间时,单位质量除尘能耗几乎没有变化,但设备能耗随负荷率的增加而线性增大,当机组超负荷时,最佳单位质量除尘能耗值会大幅上升,使得系统工作效益较低。

基于TRIZ创新方法的巷道降尘装置改进设计

基于发明问题解决理论(TRIZ)创新方法改进设计了巷道降尘装置,提升装置的降尘效果和效率,为从事煤矿开采的工作人员提供更加良好的工作环境。从TRIZ创新方法的基本工作原理出发,使用过程化预测方式尝试升级降尘装置的待创新结构,实现最终降尘装置的改进设计。使用模拟试验平台模拟分析改进的降尘装置的性能。分析结果显示,改进设计的降尘装置对于巷道之中的不同位置粉尘均具有较好抑制效果,装置使用时间增加能够使得粉尘质量下降;同时还能综合性地提升巷道中的降尘效率,获得较好降尘效果。

钻爆施工隧道喷雾降尘数值模拟分析

为研究喷雾系统对隧道开挖后粉尘浓度的影响规律,采用Fluent软件建立长度为50m的隧道通风数值仿真模型,研究压入式风管风速、喷射角度、喷嘴数量和喷嘴至掌子面距离对喷雾除尘效率的影响。研究表明:随着风管风速的增加,粉尘颗粒加速运动,并且粉尘浓度最大位置逐渐远离掌子面。增加喷嘴数量可增大喷雾与粉尘的接触面积,提高粉尘颗粒与水雾作用的概率;在设置5个喷嘴且喷射角度为90°的条件下有利于降低粉尘浓度。喷嘴距离掌子面10m时可有效限制掌子面释放的粉尘,提高除尘效率。

中心型蝶阀流阻特性数值仿真模拟及试验研究

为了弄清中心型蝶阀的流阻特性,先采用Fluent软件对通风除尘系统中一种φ560的中心型金属密封蝶阀不同开度下的流阻特性进行数值仿真模拟,通过设置试验测试蝶阀不同开度下的阻力系数,比较试验值与模拟值吻合程度,以验证仿真模拟的正确性,最后基于实验数据通过流阻特性对比分析,将全轴蝶阀改为双端轴蝶阀。仿真结果表明,在全开状态下双端轴蝶阀的流阻系数比全轴蝶阀有一定减小,达到了减小流阻的工程目的。