电收尘器的计算与选型

随着对环境保护的要求日益严格,应用一次性投资大、收尘效果好的电收尘器的单位迅速增加。收尘器的选型很关键。根据力河化肥厂磷石膏制酸联产水泥系统窑尾电收尘器的参数,详细计算电收尘器的基本型式、外型尺寸、主要参数。该厂窑尾电收尘器,入口含尘平均57g/m3,气量75065m3/h,收尘效率99.5%,与收尘效率75%的旋风除尘对比,因减少物料损失,年可增加收益95万余元。     

An inter-laboratory evaluation of new multi-element reference materials for atmospheric particulate matter measurements

Eight institutes using 12 different instruments analyzed newly developed multi-element reference materials (RM) for atmospheric particulate matter (PM) measurements. These RM have the potential to fill a gap in the currently available quality assurance resources for element analysis of PM samples such as X-ray fluorescence and inductively-coupled plasma mass spectrometry. This study evaluates the performance of these new RM generated by the University of California, Davis. The methodological challenge was to determine the reference loadings on the RM. Gravimetry is the most robust method to determine the sample deposit mass but cannot be used for these RM because some solution components are volatile and result in unpredictable total mass loadings on the RM. Instead of using gravimetry, a single well-measured element, along with the assumption that the relative mass fractions in the solutions were maintained in the aerosol deposited on the filters, was used to determine the reference loadings on the RM. This assumption appears to be valid for most elements in the solutions; notable exceptions include volatile species such as chlorine and bromine. Results from the 12 different instruments in the inter-laboratory evaluation agreed very well with the reference loadings (adjusted R² > 0.9 and slope between 0.7 and 1.3) for 17 of the 28 elements. In many cases, one or two instruments did not meet the performance criteria, which points to individual instrument calibration problems. For the 11 elements that did not perform as well, development work continues, and this intercomparison helped identify and fix a source of contamination in the system used to create the RM.

Copyright © 2019 American Association for Aerosol Research     

碳玻璃钢电除雾器的应用及改造

针对方管型立式碳玻璃钢电除雾器运行中存在的问题,进行了技术改造,更换采用了钛合金芒刺极线,既有良好导电性又有耐腐蚀性的上部阴极框架主、副梁、钛合金带刺吊杆、及集中向瓷瓶箱提供热风等,改造效果良好。     

Influence of gas velocity on the particle collection and reentrainment in an air-cleaning electrostatic precipitator

Particle deposition and reentrainment experiments were performed in a two-stage electrostatic precipitator (ESP), consisting of positive corona precharger and collecting electrode sections. Attention was focused on studying the indoor air pollution deposition and reentrainment into six size ranges from 0.3 to >10?μm. Tests were performed in an office room (200?m³) for airflow velocities from 1.4 to 8?m/s. The effect of airflow velocity on the collection efficiency of the ESP was investigated both experimentally and analytically to study reentrainment phenomena in a turbulent flow. A stationary two-dimensional analytical model was carried out by modeling the particle transport. The boundary conditions for charged particles on collecting and repelling electrodes were determined by physical considerations, including chaotic and drift motions, the reflection of charged particles from a surface, and the reentrainment of charged particles. A decrease in the experimental collection efficiency for large particle diameters (≥0.5?μm), as compared to the theoretical prediction, was interpreted as the reentrainment of particles. The size-resolved dust reentrainment fluxes from the collecting electrode were evaluated in two limiting cases, considering that either the reentrained particles are not charged or that they are charged as the particles in the deposition flux. Dimensional analysis is applied to these results, introducing the wall friction velocity as a universal parameter that determines the flow character. In general, the particles with diameters <5?μm and >5?μm exhibit different reentrainment behavior.

Copyright © 2018 American Association for Aerosol Research     

电捕焦油器故障的原因及改进措施

通过对电捕焦油器故障原因的分析,采取了相应措施。改造后的电捕焦油器能够安全、稳定运行,并且提高了电捕焦油器后煤气的质量。     

硫酸系统电除尘器的运行与改进

介绍160kt／a硫酸系统的S4L40型电除尘器的结构、运行和改进情况。通过严格控制炉气进口含尘量、防止超温运行、加强日常维护等措施，电除尘器运行15年不大修。当系统生产能力达200kt／a时，电除尘器出口含尘量仍小于300mg／m^3，完全能够满足系统稀酸洗净化工艺的需要。     

Development of a novel simulated diesel particulate matter generator system

We introduce a simulated diesel particulate matter (DPM) generator which can resolve the disadvantages of conventional soot generators and be helpful in studying reduction mechanism of DPM in DPM reduction devices. Considering characteristics of DPM, the nucleation mode was reproduced with H₂SO₄ and benzene saturators, which can produce particles in the size range 15–30 nm. The accumulation mode, which consists of particles in the size range 70–100 nm, was reproduced with a carbon spark discharge generator and a benzene saturator. In our system, bimodal distributions, which commonly occur during the idling and light load operations of diesel vehicles, could be simulated at the laboratory scale by simply changing the flow rates of the carrier gas and of H₂SO₄. The accumulation mode, which is mainly generated at heavy engine loads without a diesel oxidation catalyst (DOC) and at light engine loads with a DOC, was also simulated by changing the applied voltage at a carbon spark discharge generator or the flow rates of the carrier gas containing the carbon particles. To evaluate the performance of the DPM generator, we measured the chemical components and morphology, and compared the size distributions of the emitted particles with them of real DPM under various engine operating conditions and sulphur contents of fuel.     

Physical,chemical and electrical analysis of dust generated from cement plants for dust removal with an electrostatic precipitator

The physical, chemical and electrical characteristics of cement dust generated from a cement plant have been investigated by using a dust analyzer and a high voltage conductivity cell based on JIS B 9915. Major constituents of raw material cement dust generated from the first grinding process are CaO (41.77%), SiO₂ (11.72%), Al₂O₃ (3.45%), and Fe₂O₃ (1.47%), while the cement clinker dust generated from the second grinding process consists of mainly CaO (48.09-65.50%), SiO₂ (14.02-21.56%), Al₂O₃ (2.86-3.76%), and Fe₂O₃ (1.77-2.66%). Size distribution of the raw material cement dust is bi-modal in shape and the mass median diameter (MMD) is 3.68 μm, whereas the cement clinker dust also displays bi-modal distribution and the MMD of the cement clinker dust is in the range of 7.89-58.78 μm. The resistivity of raw material cement dust is so high as 10¹⁴ ohm·cm at 300 °C, that cement dust would not precipitate well by the electrostatic precipitator.     

Relationship between redox activity and chemical speciation of size-fractionated particulate matter

Background  

Although the mechanisms of airborne particulate matter (PM) related health effects remain incompletely understood, one emerging hypothesis is that these adverse effects derive from oxidative stress, initiated by the formation of reactive oxygen species (ROS) within affected cells. Typically, ROS are formed in cells through the reduction of oxygen by biological reducing agents, with the catalytic assistance of electron transfer enzymes and redox active chemical species such as redox active organic chemicals and metals. The purpose of this study was to relate the electron transfer ability, or redox activity, of the PM samples to their content in polycyclic aromatic hydrocarbons and various inorganic species. The redox activity of the samples has been shown to correlate with the induction of the stress protein, hemeoxygenase-1.     

Development of a new personal air filter test system using a low-cost particulate matter (PM) sensor

Abstract

The extensive use of air filters has encouraged advances in both the fabrication and characterization of air filter technology. An affordable and accessible means of assessing the quality of air filters is greatly needed because of the high demand for these filters. We developed a personal air filter test (PAFT) system for measuring filter pressure drop, efficiency, and quality of filtration. The PAFT system utilizes a PM sensor (Sharp, GP2Y1010AU0F) to measure filtration efficiency. PM sensor performance was evaluated and optimized to guarantee its suitability for this application. The sensor performance evaluation studied the output responses to sampling flow, particle diameter, and PM sources. We also improved the sensor’s sensitivity. The experimental results show that the sensor had no significant influence on the sampling flow. The sensor output was highly dependent on the particle size and PM source, but its response curves remained linear, which was an advantage for filter efficiency measurement. We measured the efficiency of nanofiber filters of various efficiencies, comparing the results to a reference efficiency as measured by a CPC (TSI, 3772). The test resulted in a filtration coefficient (K_f), which was used to correct the PAFT efficiency measurement results. We also conducted filtration efficiency tests on commercial mask filters and the results showed good agreement to the reference, with a small average error of about 2.5%. The complete design of the PAFT and experimental methods is discussed in detail.

Copyright © 2020 American Association for Aerosol Research     

机立窑高压静电除尘器的研究应用

本文根据机立窑烟气的特点,着重介绍一种新型耐腐蚀、抗结露立窑高压静电除尘的研究及应用,为立窑厂的环保除尘提供一种新设备,开拓一个新思路。     

如何克服电除尘器绝缘子的热击穿和绝缘老化

电除尘器绝缘子一般都是在一定温度的高压电场中工作,在电场和温度场的复合作用下,绝缘子的热击穿和绝缘老化是造成其绝缘失效的主要形式。在以固体电介质为中心的绝缘组合中,当受电场和温度场复合作用注入的能量大于散热量时,绝缘子本体温度上升直至发生击穿。电除尘器绝缘子的热击穿不仅取决于电场强度,还与周围的环境温度和材料本身的特征有关。通过研究绝缘材料在高温下的电学性能,尽量选择t_e值(当材料电阻率下降至1 MΩ·cm时的温度)较高的材料制造电除尘器绝缘子,优化绝缘配合的设计,设法均匀绝缘子周围的电场,可有效地阻止热击穿和延缓绝缘老化,提高电除尘器绝缘子的适应性和可靠性,以满足电除尘器高温、高压电场的特殊绝缘要求。     

新型静电除焦油装置在化肥厂的应用

从70年代起，电除焦装置已在国内应用，但因存在诸多问题，效果不好，未能解决氮肥厂半水煤气中煤焦油危害压缩机的难题。90年代初，杭州余杭工程环保设备厂对传统电除焦所存在问题进行深入调研、改进、试验，研制成功了新型JC－Ⅰ、Ⅱ型静电除焦油器，经过长期使用验证，在全国同类产品中获得了广大用户好评，于1997年12月18日通过省级新产品技术鉴定，技术达到国内先进水平。1998年为适应氮肥厂生产规模的扩大，在总结JC－Ⅰ、Ⅱ型使用经验基础上，改进内部结构，设计、制作了JC－Ⅲ型，第一次在江苏新沂化肥厂投运就取得良好效果（该厂当时合成氨年产量为60kt)。2000年，除焦油器采用微机（EPIC）控制，先后在山东德州、平原、东平、济南化肥厂和江苏连云港等化肥厂得到成功应用，现已全面推广。     

A measuring system for particle impact velocities and application in a pneumatic transport line

A detector for impact velocity measurements was developed and calibrated.Measurements of particle density profiles, distribution of incident momentum flux on the pipe wall and the distribution of radial particle velocity over a cross section of a horizontal pipe in the established flow region in a pneumatic conveying system, were performed and compared with pressure loss data.     

电除尘(雾)器的高压供电技术及装置

阐述了用于电除尘(雾)器的几种不同高压直流电源的工作原理和特点.其中详细叙述了目前使用较多的两种电源--可控硅电源和L-C恒流电源,简要介绍了软特性准稳定直流电源、脉冲供电电源、高频开关电源、高压逆变直流电源等其它几种供电技术.     

Characteristics of an electrostatic precipitator for submicron particles using non-metallic electrodes and collection plates

We have developed a novel ESP that uses an anticorrosive carbon brush precharger and plastic collection plates into which metallic films are inserted. The collection efficiency of the ESP was measured using ultrafine KCl particles by varying the applied voltages, the number of channels in the charger, the gap between the collection plates, and the air flow rates. Tests of loading and cleaning on the collection plates were also conducted using JIS class # 8 dusts and KCl particles.The experimental results showed that the precharger (400×400×800 mm³) generated a lot of unipolar ions whilst producing negligible concentrations of ozone (<5 ppb), and that when the ESP was operated with 16 channels of ionizers and a 10 mm gap between the collection plates (400×400×185 mm³), it removed more than 95% of the ultrafine particles with a power consumption of only 5 W and a pressure drop of 5 Pa per 1200 m³/h at 2 m/s. It was also shown that by increasing the applied voltage and the number of channels in the charger, and by decreasing the gap between the collection plates, an improvement in the collection efficiency of the ESP could be achieved for a scale-up. It was also found that the collection efficiency for the ultrafine particles fell from approximately 95% to 50% after dust loading with 100 mg/m³ of the JIS dusts for 2 h, but then recovered perfectly to the efficiency of the initial state after the collection plates were sprayed with water at 25 L/min for 4 min.     

A new method for identifying the modes of particulate matter from pulverized coal combustion

Knowledge of the modality of the size distribution of particulate matter (PM) from pulverized coal combustion is of great significance from the viewpoint of exposure and risk assessment. Mass or number size distributions are usually used in modality analyses, but sometimes the central particle mode fails to be detected due to overlapping. This work provides a new method for identifying particle modes using mass fraction size distributions of the aluminum (Al). Five Chinese pulverized coals of different ranks were burnt in a laboratory drop tube furnace at 1673 K. The produced PM was size segregated by a low pressure impactor and subjected to elemental composition analysis by X-ray fluorescence (XRF). Particle mass size distributions, mass fraction size distributions of the Al and sulfur (S) were obtained for all the particle samples. The mass size distributions of four coal ash samples all show three distinct particle modes, with a central mode at approximately 2 µm, while the mass size distribution of the LPS coal ash sample only indicates two particle modes. However, the mass fraction size distributions of the Al for all ash samples, including the LPS coal ash sample, generally show three particle modes. The obscurity of the central mode in the mass size distribution of the LPS coal ash sample is expected to be a consequence of the merging of it into the coarse mode. The formation of the central mode is attributed to the more pronounced heterogeneous condensation or adsorption of vaporized species on fine residual ash particles, whose origins are still unclear at present. This is further confirmed by examination of the mass fraction size distributions of the S. These results show that mass fraction size distributions of the Al seem to be more effective in identifying particle modes and their size boundaries than particle mass size distributions.