电改袋除尘器风量的测定方法及问题处理

减少细颗粒物排放是水泥工业大气烟尘排放的关键。随着《水泥工业大气污染物排放标准》GB 4915-2013)的发布,对颗粒物排放的要求更趋严格。行业一致认为,电除尘器改为袋除尘器是颗粒物源头降低排放的仅有途径,是减少大气污染物排放的主力军。     

新一批大气污染源清单编制指南发布

<正>环境保护部日前发布第二批大气污染物源排放清单编制技术指南,涉及大气可吸入颗粒物(PM10)、道路机动车、非道路移动源、生物质燃烧源、扬尘颗粒物等,以强化科技支撑大气污染防治,指导各地开展大气排放清单编制。据环保部相关负责人介绍,排放清单是识别污染来源、支撑模式模拟、分析解释观测结果和制定减排控制方案的重要基础,对于探究大气化学与气候相互作用、识别大气复合污染来源等科学问题,以及污染物总量减排、空气质量达标等环境管理问     

平板玻璃行业大气污染及治理技术

针对平板玻璃行业产生的严重污染问题,分析了平板玻璃行业大气污染物粉尘、烟尘、二氧化硫、氮氧化物的排放情况,总结平板玻璃行业大气污染物排放存在的主要问题,分析对比旋风除尘器、湿式除尘器、电除尘器和布袋除尘器除尘技术措施;传统石灰石(石灰)-石膏法、双碱法和喷雾干燥吸收法脱硫技术措施;3R工艺、选择性催化还原法和非催化选择性还原法脱硝技术措施,实现平板玻璃行业大气污染物达标排放。     

P84纤维和普抗纤维性能介绍及应用

1前言 随着国家对大气治理力度的加大,对排放浓度要求越来越严,其它一些除尘器已不能满足新标准的要求,唯有袋式除尘器能实现这一点.滤袋作为袋式除尘器的关键部件,其性能直接影响着排放浓度和使用寿命,滤袋器的发展,远远跟不上滤袋本身的发展,新的滤材不断出现,下面仅对两种性能较突出的P4纤维和普抗纤维的性能及应用进行初步探讨.     

燃烧源可吸入颗粒物声波团聚研究进展与展望

燃烧过程是大气可吸入颗粒物PM10的重要来源,控制燃烧源PM10排放已引起广泛关注,目前技术发展的主要途径是设置预处理阶段使细颗粒凝并成较大颗粒后用常规除尘设备脱除,外加声场可使PM10团聚长大;从声波团聚的宏观效果及微观机理试验2个方面对可吸入颗粒物声波团聚研究现状进行了述评,分析了声波团聚存在的主要问题及其今后需继续进行的研究方向,并介绍了作者的初步研究结果。     

燃煤锅炉烟气除尘方案的选择

概述了燃煤锅炉在用现状、锅炉烟尘排放标准以及正在修订中的《锅炉大气污染物排放标准》基本情况。介绍了文丘里水膜除尘器、电除尘器以及电袋复合除尘器等锅炉烟气除尘技术的实际应用情况,探讨了除尘器的选择方法,并给出不同燃煤锅炉除尘方案的选用建议。     

三废混燃炉电-袋复合除尘工艺的工程实践

随着国家对锅炉大气污染物排放标准要求的提高,云南云天化红磷化工有限公司(简称红磷化工)50 t/h三废混燃炉电除尘器由于工艺落后、设备老化等原因,其尾气排放已不能符合相关排放标准的要求。结合电除尘器及袋式除尘器的技术优缺点,在原电除尘器的基础上进行了电-袋复合除尘工艺技改,保留第一级静电除尘器,后三级电除尘器改为袋式除尘器。技改后,三废混燃炉尾气排放达到了预期效果。     

超低排放长袋脉冲袋式除尘器清灰系统设计探讨

长袋脉冲袋式除尘器在超低排放技术改造中发挥了重要作用,清灰系统的设计对除尘器出口排放浓度影响较大,合理的清灰系统设计是实现超低排放的重要技术手段。     

LFEF玻纤袋除尘器的改进设计

LFEF立窑和烘干机玻纤袋除尘器自从1984年研发至今，在全国已经推广上千台，并取得了良好的效果，成为立窑和烘干机除尘的首选设备。随着新修订的GB4915—2004（水泥工业大气污染物排放》标准的实施，对立窑和烘干机的粉尘排放提出了更高的要求。针对LFEF玻纤袋除尘器设备结构存在的一些缺陷进行了改进，并对控制技术和滤料的选择进行了细化，提高了除尘器的除尘效率，降低了粉尘排放浓度。     

电改袋除尘器的二次改造

随着新版《水泥工业大气污染物排放标准(GB 4915-2013)》的发布,重点地区水泥窑及粉磨除尘器排放浓度要求20mg/m~3(标),已有的电改袋除尘器原设计排放浓度为30mg/m~3(标)。企业如何在投资最少的情况下,二次改造电改袋除尘器,使其排放浓度适应越来越严格的环保法规?过滤机理的研究表明,减少排放浓度的最优方法是增加过滤面积,降低过滤速度,工程上通过增加袋室以及CFD仿真模拟来实现。     

Removal of fine particles by heterogeneous condensation in the double-alkali desulfurization process

Removal of fine particles by heterogeneous condensation in the rotating-stream-tray scrubber was investigated experimentally for the double-alkali desulfurization process in this paper. A supersaturated vapor phase, necessary for condensational growth of fine particles, was achieved in the SO₂ absorption zone and at the top of the scrubber by adding steam in the gas inlet, between the pieces of rotating-stream-tray and above the desulfurization liquid inlet of the scrubber, respectively. Fine particles grew in size by vapor heterogeneous condensation with the particles acting as nucleation centers. Then the condensational grown droplets were removed efficiently by the desulfurization liquid and a high-efficiency demister. In order to optimize the removal process, the influences of temperature of inlet flue gas and desulfurization liquid, steam addition method and amount of steam added on the particle removal efficiency were presented. The results show that a few fine particles could be removed in the rotating-stream-tray scrubber. The removal efficiency can be significantly improved for various steam addition cases, and the improve performance is related to the method and the amount of steam addition. Particle removal efficiency with steam added between the pieces of rotating-stream-tray is higher than that of else steam addition cases.     

喷淋洗涤条件下水汽饱和度分布特性

为在脱硫喷淋塔中借助蒸汽相变原理促进PM_2.5凝结长大,需要在塔内建立适宜的过饱和水汽环境。基于此,建立喷淋洗涤条件下气液两相热质传递模型,系统研究了操作参数对塔内饱和度分布特性的影响规律。结果显示,通过降低喷淋液温度、增加塔进口烟气含湿量,以及在喷淋区上方添加蒸汽均能够在塔内建立过饱和水汽环境;采用较大的液气比、较小的喷淋液滴直径有利于水汽饱和度的提高。获得了改变操作参数在脱硫喷淋塔内建立过饱和水汽环境的措施,对实际的脱硫除尘工艺的设计和运行具有指导意义。     

Nucleation of Ethylene Glycol Vapor and Growth of Sub-10-nm Particles in Nanoparticle Size Magnifier

We investigated the rates of heterogeneous and homogeneous nucleation of ethylene glycol vapor onto sub-10-nm particles in a newly developed condensation device called nanoparticle size magnifier (NanoPSM). The saturation ratio in the NanoPSM is precisely controlled by vapor-feeding system and mixing section, which are designed based on an earlier particle size magnifier (PSM) developed by Okuyama et al. (1984). Size-classified NaCl nanoparticles smaller than 10 nm in mobility diameter are used as heterogeneous nuclei for the condensation of ethylene glycol vapor. The activation efficiency and growth rate of the activated nuclei are determined by a pulse height analysis using an optical particle counter (OPC). A computer fluid dynamics (CFD) simulation is employed to calculate the profiles of the gas velocity, temperature, vapor concentration, and resulting supersaturation in the NanoPSM. Annular high-supersaturation region is generated around the mixing boundary between cold aerosol and hot vapor. The experimental activation efficiency is 50% for 4.5-nm and 0.8% for 2 nm NaCl particles, through the subsequent growth of droplets to 2 μm in diameter. The experimental data are in fairly good agreement with the predicted activation efficiencies based on the classical Kelvin-Thomson theory when the local profiles of supersaturation are taken into account.     

Growth of aerosol particles by adiabatic expansion at the throat of a venturi scrubber

The condensational growth of aerosol particles in the throat section of a venturi scrubber and the contribution of it to the dust collection efficiency were discussed.The condensable water vapor produced in the throat of venturi was quantitatively obtained for various conditions assuming the change in pressure and temperature to be adiabatic process. In terms of this condensable water vapor and the particle number concentration, the diameter of grown particles was determined, and the degree of contribution due to particle growth to the particle collection by venturi scrubber was evaluated as the change in particle collection efficiency involved in the particle growth.Experimental verification of the above results was qualitatively made by changing the humidity of the inlet gas, which is the most important property dominating the particle growth, in the particle collection by venturi scrubber.     

Removal of fine particles in wet flue gas desulfurization system by heterogeneous condensation

A novel process to remove fine particles with high efficiency by heterogeneous condensation in a wet flue gas desulfurization (WFGD) system is presented. A supersaturated vapor phase, necessary for condensational growth of fine particles, was achieved in the SO₂ absorption zone and at the top of the wet FGD scrubber by adding steam in the gas inlet and above the scrubbing liquid inlet of the scrubber, respectively. The condensational grown droplets were then removed by the scrubbing liquid and a high-efficiency demister. The results show that the effectiveness of the WFGD system for removal of fine particles is related to the SO₂ absorbent employed. When using CaCO₃ and NH₃·H₂O to remove SO₂ from flue gas, the fine particle removal efficiencies are lower than those for Na₂CO₃ and water, and the morphology and elemental composition of fine particles are changed. This effect can be attributed to the formation of aerosol particles in the limestone and ammonia-based FGD processes. The performance of the WFGD system for removal of fine particles can be significantly improved for both steam addition cases, for which the removal efficiency increases with increasing amount of added steam. A high liquid to gas ratio is beneficial for efficient removal of fine particles by heterogeneous condensation of water vapor.     

Experimental investigation on removal of coal-fired fine particles by a condensation scrubber

The removal of coal-fired fine particles by heterogeneous condensation of water vapor in a scrubber was investigated. Supersaturated vapor phase necessary for the condensation growth of fine particles was achieved in the scrubbing zone as well as in the top of the scrubber by means of steam addition in the gas inlet and above the scrubbing liquid inlet, respectively. The condensation grown droplets were then removed by the scrubbing liquid and high-efficient demister. Influences of the steam addition amount, the temperature difference between the inlet gas and scrubbing liquid, and the liquid-to-gas ratio, etc. on removal efficiency were examined. The results show that with a steam addition amount of flue gas, number removal efficiencies of more than 60% and 70% can be attained for the two cases of steam addition, respectively. For the cases with steam addition in the gas inlet of scrubber, higher temperature difference between the inlet gas and scrubbing liquid enhances the removal of fine particles. Under the conditions of steam addition above the scrubbing liquid inlet, the removal efficiency decreases with increasing temperature difference. The removal efficiency can be effectively improved by increasing the liquid-to-gas ratio for both steam addition modes.     

Phoretic phenomena in tar vapor-particulate mixture separation from fuel gas streams

Analytical models were developed to predict the performance of a spray scrubber for separation of tars from gasifier off-gas streams. The models included heat transfer, mass transfer, condensation, nucleation, temperature and flow fields, and various phoretic phenomena involved in droplet-particle and droplet-vapor interaction and collection. The models indicate that for the tar particulates, both Brownian diffusion and inertial impaction, rather than diffusiophoresis and thermophoresis, are the more important phoretic forces causing the collection. For the limiting case of all tars being present only as vapor, the efficiency of their removal by condensation on water spray droplets could be extremely high. Scrubbing experiments were carried out on the hot gas/tar stream evolved from the simulated devolatilization section of a laboratory fixed bed gasifier. The combined overall collection efficiency for a mixed particulates and vapor stream compares satisfactorily with the model predictions.     

洗涤塔脱除燃烧源超细颗粒的实验研究

在填料洗涤塔中进行了利用蒸汽相变原理促进燃煤和燃油超细颗粒凝结长大并高效脱除的实验研究;采用电称低压冲击器(ELPI)、SEM及XPS对两种燃烧源细颗粒凝结洗涤前后的数浓度、粒径分布、形貌和元素组分进行了分析测试,考察了洗涤塔进口气液温差、进口烟气含湿量及液气比等对脱除效率的影响。结果表明,燃煤和燃油产生的超细颗粒形貌和组分具有较大的差别,燃煤超细颗粒主要为硅铝矿物质,而燃油超细颗粒主要为含炭物质;在相同条件下,燃煤超细颗粒相变脱除效果优于燃油超细颗粒;脱除效率随洗涤塔进口气液温差的增大而提高,在相同进口气液温差下,增大进口烟气含湿量可显著提高超细颗粒的脱除效率;液气比的影响与填料洗涤塔内是否存在蒸汽相变有关;通过合理调节进口烟气含湿量及进口烟气与洗涤液的温差在填料塔内建立微粒凝结长大所需的过饱和水汽环境可有效脱除燃烧源超细颗粒。     

Minimizing Concentration Effects in Water-Based,Laminar-Flow Condensation Particle Counters

Concentration effects in water condensation systems, such as used in the water-based condensation particle counter, are explored through numeric modeling and direct measurements. Modeling shows that the condensation heat release and vapor depletion associated with particle activation and growth lowers the peak supersaturation. At higher number concentrations, the diameter of the droplets formed is smaller, and the threshold particle size for activation is higher. This occurs in both cylindrical and parallel plate geometries. For water-based systems, we find that condensational heat release is more important than vapor depletion. We also find that concentration effects can be minimized through use of smaller tube diameters, or more closely spaced parallel plates. Experimental measurements of droplet diameter confirm modeling results.

© 2013 American Association for Aerosol Research     

天然气净化用旋风分离器气液分离性能

为了系统评价天然气净化用旋风分离器在含液量低时的气液分离性能,利用滤膜采样称重法和Welas在线测量法测量了旋风分离器在入口气速8～24 m·s^-1、入口液体浓度0.1～2 g·m^-3时的分离效率和粒径分布;对比了相同入口浓度下旋风分离器气液分离性能和气固分离性能的异同。实验结果表明,在入口气速为8～24 m·s^-1、入口液体浓度为0.1～2 g·m^-3时,旋风分离器的气液分离效率随着入口气速和入口液体浓度的增加而增大,而出口粒径分布范围变化很小;与气固分离相比,在相同的入口气速和入口浓度下,旋风分离器的气液分离效率要高2%～6%;另外,气液分离时出口液滴粒径不大于4 μm,而气固分离时出口有大于10 μm固体颗粒存在。