Das elektrische Verhalten hochohmiger Stäube

Highly resistive dusts show markedly non‐ohmic properties. The property known as specific resistivity is strongly dependent on the dust layer thickness and on the polarity of the high voltage. The current transport occurs by excess charges of both polarities, which leads to high space charge densities and induces strong electrostatic fields. The theory of electrets provides a consistent explanation of the phenomena observed so far. To investigate the electrical properties, highly resistive dusts were exposed to an electrical field with interfering corona discharges within a tip‐plate arrangement.     

高温除尘技术综述

介绍了高温除尘技术的特点,综述了国内外高温除尘设备的现状、水平以及发展趋势,并对该技术在各行业中的应用前景进行了展望。     

燃煤锅炉除尘设施改造

对金堆城钼业公司采暖锅炉除尘设施存在的问题进行了全面分析，采用麻石湿式除尘代替旋风除尘所取得的环境效益和社会效益作了详实总结和论述。     

CFD Analysis of Dust Explosion Relief System in the Counter-Current Industrial Spray Drying Tower

The aim of the paper was to evaluate the performance of venting devices in an industrial counter-current spray tower during dust explosion using a CFD model and EN14491:2006 standard. Three-dimensional CFD simulations of dust explosion in the spray tower for six different configurations of safety vents located at the top and side walls of the dryer were carried out. In the calculations, in which dust was replaced with a flammable gas-air mixture, the following parameters of dust explosion were analyzed: reaction progress, maximum and average gas temperature, gas velocity, and pressure. Reduced pressures calculated according to EN 14991:2006 standard are close to maximum pressure obtained from CFD simulations for all analyzed spatial configurations of the safety vents, which proves that the CFD model can be used both to design explosion mitigation systems and to describe the mechanism of explosion propagation in the drying chamber. Results of the calculations allowed us to evaluate the performance of analyzed venting devices, to determine the spatial configuration and parameters of venting devices that should be installed to minimize damages of the dryer construction.     

Air Pollution Due to Opencast Coal Mining and the Characteristics of Air-Borne Dust--An Indian Scenario

Opencast coal mining creates more air pollution problem in respect of dust and the fines contain coal particles, benzene soluble matters etc. To maintain the energy demand, opencast mining has been growing at a phenemenon rate in India. There is no well defined method for assessing the impacts on air quality due to mining projects. An investigation was conducted to evaluate the impacts on air quality and the characteristics of the air-borne dust due to opencast coal mining in Indian context. The study area has been described and the sources of air pollution were identified. Methodology adopted for the selection of air monitoring stations and air pollution monitoring to evaluate the impacts on air environment due to coal mining activities have been discussed. Impacts on air quality have been assessed on the basis upwind and down wind concentrations of air pollutants. SPM and RPM concentrations were found to be very high in work zone as well as surrounding locations. The SPM was subjected to particle size analysis using different techniques. It was observed that the particulates were more respirable in nature and the median diameter was around 20 w . Variation of weight percentages for different size ranges has been discussed as a function of mining activity. Benzene soluble matters and anions in SPM were found to be high in comparison to other areas. Settleable dust and its compositions were also analysed. The methodology adopted for the study may be utilised to assess the actual contribution of air pollutants due to other coal projects.     

清梳联合机工艺技术与设备创新探讨

通过利用AFis纤维检验仪对清梳联各单机在制品的测试结果 ,得出了清梳联工程中棉结、杂质的变化规律 ,并对清梳联工程中清棉打手的组合结构、清梳除杂分配、清梳联短绒控制、生条定量控制、排尘、滤尘与空调系统等重要问题进行了讨论。     

Reduction of Particle Reentrainment Using Porous Fence in Front of Dust Samples

Wind tunnel experiments were conducted to measure the emission factor of particle reentrainment from a dust sample with or without a porous fence. The effect of wind velocity, fence porosity, and distance between the fence and the dust sample on the emission factor was studied. A 20% porous fence was found to be effective for reducing the particle reentrainment at a low wind velocity of 5?m/s. When the wind velocity was increase from 7 to 15?m/s, the results show that the particle reentrainment can also be reduced in a certain region behind the fence (x/H<4,?x=distance between fence and sample; H=fence height) for the 20% porous fence. A linear multivariable regression model was fitted to the logarithmically transformed experimental data. The good fit of the regression model makes it possible to estimate emission rate as a function of the dimensionless distance (x/H), the wind velocity, and the elapsed time.     

Survival of the House Dust Mite,Dermatophagoides farinae,at High Temperatures (40–80°C)

Abstract Experiments were conducted to evaluate the survival time of randomly selected female D. farinae exposed to temperatures from 40 to 80°C and relative humidities (RHs) between 10 and 90%. Significant temperature effects were found on the length of time mites can survive under those conditions. The time needed to induce 100% mortality for female D. farinae held at 40°C varied between 39 and 84 h. At 70 and 80°C, all mites died within 5 minutes. At 50°C and above, RH had little influence and temperature alone was the determining factor for mite survival. The length of survival time decreased precipitously between 40 and 50°C, suggesting that a loss of physiological integrity of female D. farinae probably occurred in this range. The results of this study indicated that the technique of raising temperatures to above 40°C for a short duration can be used to reduce living house dust mite populations in homes significantly.     

综采放顶煤开采的安全技术

经过十几年的放顶煤开采的实践,中国较好地解决了放顶煤开采的防瓦斯、防火和防尘问题,使该技术逐渐走向成熟,并从中获得了效益。