冲击式水浴除尘器在中小工厂的使用

介绍了使用WY-1型尘粒分级仪对冲击式水浴除尘器的粒径分级效率的测定结果;用它所测得的陶瓷、建材行业主要工序排出含尘尾气中粉尘的粒径分级组成;在此基础上,测定了冲击式水浴除尘器使用于上述行业工厂主要工序的效果和预期的除尘效果。     

WY型冲击式尘粒分级仪的研制及应用

为了解空气中颗粒物对人体及环境的影响,评价除尘器的粒径分级除尘效率,为无通风除尘设备的污染源选定适用的除尘器,都需要测定颗粒物的重量粒径分级组成.为满足国内需求,研制了WY型通风管道用9级冲击式尘粒分级仪,它适用于测量通风管道和工作环境中粉尘的空气动力直径和粒径分级组成.     

水泥厂立窑烟气适宜除尘方法研究

目的 提出小水泥厂立窑烟气应选用的适宜除尘方法。方法 根据ＧＢ／Ｔ１６１５７－１９９６固定污染源排气中颗粒物的测定和气态污染物的采样方法,并使用ＷＹ－１型烟道用７级冲击式尘粒分级仪等测定了立窑烟气的温度、露点温度、粉尘浓度、粉尘粒径分级组成等特性;测定了沉降室、旋风、冲击水浴、冲击－喷雾除尘器的粒径分级除尘效率等特性。结果 在上述基础上,将除尘器与尘源进行合理匹配,提出了排放达标的几种除尘器选型组     

乡镇工业砖瓦厂适用通风除尘技术研究

为了控制乡镇砖瓦厂排放粉尘对室内外空气的污染，在改进工艺的基础上，于各产尘点设置了密闭吸尘罩，有效地控制了粉尘向周围环境扩散。根据破碎、筛分等工序排放的含尘空气及粉尘特性，采用了冲击水浴除尘器除尘，针对风选粉碎机等工序排放的含尘空气及粉尘特性，采用了冲击－喷雾联合除尘器除尘。采用上述有效控制技术后，车间工作地点粉尘浓度由原来的每立方米数百毫克降到卫生标准２ｍｇ／ｍ３以下，两套通风除尘系统排放粉尘浓度降到排放标准１５０ｍｇ／ｍ３以下。冲击水浴除尘器的除尘效率为９７．６％，阻力为１４００Ｐａ；冲击－喷雾联合除尘器的除尘效率为９７．３％，阻力为１９００Ｐａ。两种除尘器排出的污泥可返回作生产原料，无二次污染问题。该除尘器结构简单，易于管理，成本低，便于自行制作。文中还给出了两种除尘器的粒径分级除尘效率，便于其它场合下准确的选用。     

玉石雕刻作业粉尘控制的适宜技术

目的 提供玉石雕刻行业适宜的防尘技术措施。方法 车间粉尘浓度的测定按照GB／T5748－85、通风除尘系统的测定按照GB／T16157－1996的规定进行，使用WY－1型7级冲击式尘粉分级仪测定排气中粉尘的粒径分级组成和除尘器的粒径分级除尘效率。结果 采用了湿式作业，设置了适用的局部通风除尘系统：设计了专门的条缝型吸尘罩，其侧上吸罩罩口风速为2.5m/s、风量为600m^3/h；根据吸尘罩的数量及各风管的风量选定各支、干风管及总风管的直径；选择了冲击式水浴除尘器或滤袋除尘器，对玉石雕刻通风系统排出的含尘空气进行了除尘净化，除尘器的总除尘效率，前者可达97.0%，后者可达98.0%；根据通风除尘系统所需的风量、克服该系统最大阻力管线所需全压及除尘器的阻力确定了风机的机型和参数。结论 实践结果表明，所提供的玉石雕刻作业粉尘控制的适宜技术，可使作业地点粉尘浓度降低到国家卫生标准或接近卫生标准的要求；通风除尘系统排出的含尘空气可以满足排放标准的要求。     

乡镇水泥厂综合防尘适宜技术的研究

目的 研究乡镇水泥厂的适宜防尘技术,以控制尘肺病的发生。方法 采用现场和实验室相结合的综合调研方法。用示踪气体测量抽气罩的效率。按照国家标准（GB／T16157－1996）测定通风管道中的粉尘浓度。采用WY－1型冲击式尘粉分级仪测量各尘源排放粉尘的粉尘粒径分级组成和除尘器的粒径分级除尘效率。结果 （1）工程技术措施方面：提出了破碎、球磨、烘干、烧窑、物料运输和包装等工艺工序的适宜吸尘罩设计（及通用图集）,可有效地控制这些尘源的粉尘外溢。测定不同工序排放烟气的特性（烟气的温度、含水量、粉尘浓度、粉尘粒径分级组成等）,研究了多种除尘器的粒径分级除尘效率、阻力等,提出了各主要工序最适宜方案：破碎、磨机工序除尘以旋风加滤袋或静电等;烘干窑除尘以旋风加静电或冲击喷雾等;立窑除尘以沉降室加静电等;包装工序除尘以滤袋或静电等。（2）组织措施方面：完善职业卫生管理系统,包括建立组织机构、加强职业卫生服务、开展技术培训和职业卫生教育。强调“有效地控制各尘源处的粉尘,防止其向周围扩散”是防止尘肺病发生的最有效方法。结论 提出了乡镇水泥厂适宜综合防尘技术措施,可有效控制水泥尘危害。     

测量湿式除尘器粒径分级除尘效率的适用方法

目的探讨湿式除尘器测量分级效率的适用方法。方法根据对污染源颗粒物采样要求及湿式除尘器特点,采用WY-1尘粒分级仪在除尘器前后同时采样,提出测量和计算分级效率方法。结果根据WY-1各级冲击器接尘板纸垫增重,按对数正态概率分布整理数据,用自主开发的GBSS软件,快速计算冲击水浴除尘器前后粉尘粒径分级组成,除尘器前:对小于1、2、4、6、10、15、20μm不同粒径颗粒物重量%数为:0.84、2.7、8.5、15.1、26.8、38.6、47.8;除尘器后为:3.2、12.0、31.6、46.3、65.5、78.8、86.0。在此基础上,计算出除尘器分级效率E_i,值为:0.764、0.807、0.865、0.90、0.933、0.954、0.966。计算效率E_计系根据除尘器粒径分级效率和污染源粉尘粒径分级组成数据得出。已知除尘器粒径分级效率和测得的新污染源颗粒物粒径分级组成及浓度,用E_计可计算出除尘后的排放浓度,避免了除尘器选型的失误。结论提供了测量分级效率的适用方法。以实例说明测量、计算步骤及应用效果。     

吸尘罩的优选及其在玉石雕刻防尘中的应用

目的对适用吸尘罩进行优选,并在实际通风除尘系统中应用。方法用示踪气体法对吸尘罩进行优选,比较不同吸尘罩捕集效率和风量的关系;对吸尘罩前风速分布进行测定,得出罩前风速分布模型。并对吸尘罩进行空气动力性能分析,测定雕刻排气中粉尘的粒径分级组成和除尘器的粉尘粒径分级除尘效率,评估除尘器的总除尘效率。结果优选出的雕刻吸尘罩,置于切割轮正前方0.11 m处,其控制风速为0.5 m/s,能有效地控制雕刻切割轮的粉尘不向周围扩散,工作地点空气粉尘浓度由无罩时的30-297 mg/m3降低至1.1-1.7 mg/m3,吸尘罩风量为255 m3/h,为其他类型吸尘罩的50%-77%。优选出的冲击水浴除尘器,其除尘效率为97%-98%,阻力为1.5 kPa;滤袋除尘器的效率为98%-99%,阻力为2.5 kPa;除尘后尾气的粉尘浓度为20-30 mg/m3。结论提出了优选吸尘罩的设计方法及实用的除尘器,可供实际应用。     

冲击-喷雾联合除尘器的研究与应用

目的　研究适合排放气体中粒径较细粉尘的除尘器。方法　选择排放粉尘粒径 (<5μm占85 5% )较细的乡镇瓦厂原料旋风分离器尾气排放口 ,研究设计了“冲击 -喷雾联合除尘器”。结果　经测定评价 ,总除尘效率 97 3 % ,排出气体的粉尘浓度 16 0～ 14 1 8mg/m3 。结论　解决了粒径较细、粉尘浓度高、不适用于干式除尘器的粉尘净化问题 ,泥浆废水用于生产不产生二次污染 ,拓宽了水浴除尘器的适用范围 ,展示了利用分级除尘效率选择设计除尘器的方法及意义     

建材釉砖厂适宜的通风除尘措施研究

目的 探讨釉砖厂适用的通风除尘系统设计方案.方法 选择试点厂,为产尘工序设计、安装通风除尘系统并测定其控尘效果.按照GB 5748-85和GB/T16157-1996测定了工作场所和通风管道中粉尘浓度,使用WY-1型尘粒分级仪测定粉尘的粒径分级组成和除尘器的粒径分级除尘效率,并进行论证.结果 (1)轮碾、斗式提升机、筛分别设置了密闭吸尘罩,轮碾机罩罩口风速为2.5 m/s,斗式提升机、滚筒筛罩的抽风量为1800m3/(h·m2);冲模、质检吸尘罩罩口风速为5和1m/s;(2)上述工序无吸尘罩时粉尘浓度为29.5.255-3 mg/m3,设置吸尘罩后为0.7～1.8 mg/m3;(3)对通风系统排出的含尘空气采用冲击式水浴除尘器净化,除尘后尾气含尘浓度为56.5 mg/m3,除尘效率为97.6%,阻力为800 Pa.结论 釉砖厂安装通风除尘系统后,工作场所粉尘浓度由严重超标降低到1.8 mg/m3;通风系统尾气含尘浓度为56.5mg/m3达到排放标准.     

Physical collection efficiency of filter materials for bacteria and viruses

The purpose of this study was to determine the physical collection efficiency of commercially available filters for collecting airborne bacteria, viruses, and other particles in the 10-900 nm (nanometer) size range. Laboratory experiments with various polytetrafluoroethylene (PTFE), polycarbonate (PC) and gelatin filters in conjunction with Button Inhalable samplers and three-piece cassettes were undertaken. Both biological and non-biological test aerosols were used: Bacillus atrophaeus, MS2, polystyrene latex (PSL), and sodium chloride (NaCl). The B.atrophaeus endospores had an aerodynamic diameter of 900 nm, whereas MS2 virion particles ranged from 10 to 80 nm. Monodisperse 350 nm PSL particles were used as this size was believed to have the lowest filtration efficiency. NaCl solution (1% weight by volume) was used to create a polydisperse aerosol in the 10-600 nm range. The physical collection efficiency was determined by measuring particle concentrations size-selectively upstream and downstream of the filters. The PTFE and gelatin filters showed excellent collection efficiency (>93%) for all of the test particles. The PC filters showed lower collection efficiency for small particles especially <100 nm. Among the tested filters, the lowest collection efficiencies, 49 and 22%, were observed for 1 and 3-microm pore size PC filters at the particle sizes of 47 and 63 nm, respectively. The results indicate that the effect of filter material is more significant for the size range of single virions than for bacteria. The effect of filter loading was examined by exposing filters to mixtures of PSL particles, which aimed at mimicking typical indoor dust levels and size distributions. A 4-h loading did not cause significant change in the physical collection efficiency of the tested filters.     

Comparison of coal mine dust size distributions and calibration standards for crystalline silica analysis

Since 1982 standard calibration materials recommended for respirable crystalline silica analysis by the Mine Safety and Health Administration (MSHA) P7 Infrared Method and the National Institute for Occupational Safety and Health (NIOSH) X-ray Diffraction (XRD) Analytical Method 7500 have undergone minor changes in size distribution. However, a critical assumption has been made that the crystalline silica in ambient mine atmosphere respirable dust samples has also remained essentially unchanged in particle size distribution. Therefore, this work compared recent particle size distributions of underground coal mine dust and the silica component of these dusts with estimated aerodynamic particle size distributions of calibration standard materials MIN-U-SIL 5, Berkeley 5, and SRM 1878 used by two crystalline silica analysis techniques. Dust impactor sampling data for various locations in 13 underground coal mines were analyzed for the respirable mass median aerodynamic diameters. The data suggest that the MSHA P7 method will underestimate the silica content of the sample by at most 7.4% in the median size range 0.9 to 3.6 microm, and that it is unlikely one would obtain any significant error in the MSHA P7 method analysis when the method uses Berkeley 5, MIN-U-SIL 5, or SRM 1878 as a calibration standard material. The results suggest that the NIOSH Analytical Method 7500 would be more appropriate for a dust sample that is representative of the total (no cyclone classifier) rather than the respirable airborne dust, particularly because the mass fraction in the size range below 4 microm is usually a small percentage of the total airborne dust mass. However, NIOSH Analytical Method 7500 is likely to underestimate the silica content of an airborne respirable dust sample by only 5 to 10%. The results of this study also suggest that any changes that may have occurred in the median respirable size of airborne coal mine dust are not significant enough to cause any appreciable error in the current methods used for respirable crystalline silica analysis.     

Dust particle size effects on absorbed fraction values in the anterior nose

The respiratory tract model introduced in Publication 66 of the International Commission on Radiological Protection (ICRP) includes consideration of extrathoracic airways, referred to as the ET region. This region comprises the anterior nose and the posterior nasal passages, larynx, pharynx, and the mouth. The deposition of inhaled particles in the airways depends on the thermal and aerodynamic properties of the particles and equations are presented to calculate the deposition efficiency in the various regions of the tract. In its dosimetric model the ICRP assumes that none of the energy emitted by the deposited source is lost in the particles itself (i.e., no self attenuation) and the deposition is assumed to be on the inner surface of the airway of the anterior nose. Therefore, the effects of various dust particle sizes on the energy deposition in the epithelium as characterized by the absorbed fraction in the anterior nose region were not addressed in ICRP 66. Since radioactive particulate matter is carried in air within dust particles, this subject should be addressed. In this paper the effects of dust particle sizes (various equivalent volume diameters) on the absorbed fraction to the anterior nose are studied using a truncated cone model for the anterior nose. The results indicate that attenuation in the dust particles has a significant effect on the electron absorbed fraction. This effect depends on the dust particle size and the energies of the electrons emitted by the radionuclides carried within dust particles.     

用示踪气体法评价和优选吸气罩

目的 在粉尘发生源处设置适用的局部吸气罩,可以有效地控制粉尘向周围扩散,是预防尘肺病发生的有效措施。为了提供适宜吸气罩的设计,使用了示踪气体法评价吸气罩的效率,对吸气罩的设计进行优选,以提高捕集效率和降低能耗。方法 建立示踪气体评价吸气罩效率的实验风道和方法,采用人工煤气作为示踪气体。结果 实验了长方形和无延伸挡板及有特殊延伸挡板的条缝形吸气罩在不同罩口风速下对示踪气体的捕集效率。导出了捕集效率和距离的关系方程式。实验结果表明:(1)吸气罩与污染源的距离和罩口风速对捕集效率有明显的影响。当罩口风速一定时。吸气罩越靠近污染源,捕集效率越高;而在同一距离上,罩口风速越大,捕集效率就越高。(2)有延伸挡板的条缝形吸气罩的捕集效率高于无延伸挡板条缝形吸气罩,前者采用较低的罩口风速(抽风量)可以得到相应的高捕集效率。结论 使用示踪气体对吸气罩进行优选的结果表明,通过改进吸气罩的形式可以降低所需风量并达到要求的效率,从而为减少通风设施的费用提供了一种重要途径。     

Particle-Size Distribution of Polycyclic Aromatic Hydrocarbons in Urban Road Dust of Masan, Korea

Concentrations and compositions of polycyclic aromatic hydrocarbons (PAHs) in particle size fractions of road dust sampled from contrasting areas of an industrialised city in Korea are reported. The largest amounts of road dust were present in industrial areas, followed by areas subject to heavy traffic, and the lowest amounts were associated with a residential area. The highest concentrations of PAHs were recorded in road dust sampled from the areas with the heaviest traffic (0.45-4.1 μg/g), followed by industrial areas (0.1-3.56 μg/g), with the lowest concentrations associated with a residential area (0.32-1.95 μg/g). PAH concentrations in the fractionated dust from the industrialised areas exhibited an inverse correlation with particle size. Although a similar general pattern was observed in the areas of heavy traffic, some increased concentrations associated with larger particles possibly reflect petrogenic contributions. Particles in road dusts from the residential area were generally smaller than those from the other areas, with PAH composition dominated by pyrogenic sources. PAH compositional profiles, evaluated through diagnostic isomeric ratios, indicate that exhaust emissions, rather than crankcase oils or tire and asphalt abrasion, are the major polluting source.