卧式电除尘器电晕极优化实验研究

运用粉尘粒子荷电原理,对四种电晕极的主要技术性能进行了试验研究,探讨了卧式电除尘器的最佳极配形式。     

地矿部门坑道作业尘毒危害情况

对坑道中的尘毒进行了测试,并根据测试结果提出了一些建议。     

胶带输送机防尘治理综合改进措施

叙述了胶带输送机现有防尘罩的不足及改进措施。     

Potential for childhood lead poisoning in the inner cities of Australia due to exposure to lead in soil dust

This article presents evidence demonstrating that the historical use of leaded gasoline and lead (Pb) in exterior paints in Australia has contaminated urban soils in the older inner suburbs of large cities such as Sydney and Melbourne. While significant attention has been focused on Pb poisoning in mining and smelting towns in Australia, relatively little research has focused on exposure to Pb originating from inner-city soil dust and its potential for childhood Pb exposures. Due to a lack of systematic blood lead (PbB) screening and geochemical soil Pb mapping in the inner cities of Australia, the risks from environmental Pb exposure remain unconstrained within urban population centres.     

三峡上游地区一次西南涡暴雨过程中尺度特征诊断和数值模拟

结合高空、地面实况观测数据以及1°×1°NCEP客观再分析资料,对2009年6月28日20时至29日20时(北京时)发生在三峡上游地区的一次区域暴雨过程进行了中尺度特征诊断,结果表明本次过程是东北低涡和副高稳定少动的大尺度环流背景形势下,由于高原低值系统在东移过程中与西南涡结合而产生的强降水天气过程。高原上不稳定能量的扰动和下传为西南涡的产生提供了必要能量条件,高低层的水汽平流和水汽辐合的交汇地带与最强降水带存在较好的一致性。另外,利用WRF中尺度数值模式对该次过程进行了数值模拟,结果显示在同化了地面和高空常规观测资料后,模式模拟效果得到明显改善,模拟降水能够大致体现该次过程的总的降水演变和分布情况,但后期模拟降水偏大。数值诊断结果发现,盆地西部与上升气流相伴的正涡度柱的演变过程与强降水的发生过程密切相关,该因子对于正确预报降水发生时间具有指示意义。     

磨细粉煤灰自动装车除尘系统的研制

针对磨细粉煤灰由储料仓向罐式汽车内装料的作业特点,研制了自动化装车除尘系统,解决了装车过程中的粉尘污染问题,并实现了装车过程的自动化。     

Characterizing Storm Hydrograph Rise and Fall Dynamics With Stream Stage Data1

Abstract: Storm‐flow transients (i.e., hydrograph rise and fall dynamics) may represent an important aspect of understanding streamflow dynamics. However, little is known about how temporal resolution of transient data and climate variability may color these potential indicators of hydrologic pattern or condition. Warm‐season stream stage and rainfall were monitored continuously (5 min) during the 2002 water year in eight tributaries of the Little Miami River (Ohio), which drain 17‐58 km² catchments. Rise rates generated using 5‐min data were different than those generated with mean daily data [calculated with the Indicators of Hydrologic Alteration (IHA) software], though fall rates were similar for fine and coarse temporal data. This result suggests that data with low temporal resolution may not be adequate to fully represent the dynamics of storm rise rates. Conversely, fall rates based on daily stage data (via IHA) were similar to those based on the 5‐min data, and so daily mean data may be appropriate for characterizing fall rates. We next analyzed the possible correlations between rainfall variability and storm‐flow stage dynamics. We derived rise and recession rates from storm stage hydrographs by assuming exponential rise and decay of a runoff peak. We found that raw rise rates (R_raw) were correlated with both the maximum rainfall rate and the time to the centroid of a rain event. We subsequently removed the trend based on these rainfall characteristics, which yielded new representations of rise rates abbreviated as R_rate and R_tcent, respectively, and that had lower variability than the uncorrected (raw) data. Fall rates were found to be independent of rainfall characteristics. Due to the predominant influence of stream hydrology upon aquatic biota and nutrient fluxes, our work suggests that these stage data analysis protocols can refine or otherwise reduce variability in these indices by accounting for relevant factors such as rainfall forcing. These protocols for derivation of transient indices should be tested for their potential to improve correlations between stream hydrology and temporally aligned biotic data and dissolved nutrient fluxes in streams.     

Flame behaviors and pressure characteristics of vented dust explosions at elevated static activation overpressures

Dust explosion venting experiments were performed using a 20-L spherical chamber at elevated static activation overpressures larger than 1 bar. Lycopodium dust samples with mean diameter of 70 μm and electric igniters with 0.5 KJ ignition energy were used in the experiments. Explosion overpressures in the chamber and flame appearances near the vent were recorded simultaneously. The results indicated that the flame appeared as the under-expanded free jet with shock diamonds, when the overpressure in the chamber was larger than the critical pressure during the venting process. The flame appeared as the normal constant-pressure combustion when the pressure venting process finished. Three types of venting processes were concluded in the experiments: no secondary flame and no secondary explosion, secondary flame, secondary explosion. The occurrence of the secondary explosions near the vent was related to the vent diameter and the static activation overpressure. Larger diameters and lower static activation overpressures were beneficial to the occurrence of the secondary explosions. In current experiments, the secondary explosions only occurred at the following combinations of the vent diameter and the static activation overpressure: 40 mm and 1.2 bar, 60 mm and 1.2 bar, 60 mm and 1.8 bar.     

Application of CFD on the sensitivity analyses of some parameters of the modified Hartmann tube

The aim of this work is to determine the influence of operating parameters such as the dispersion pressure, the ignition delay and height on the dust flammability. A Computational Fluid Dynamics (CFD) simulation, based on an Euler–Lagrange approach, was developed with Ansys Fluent™ and validated experimentally. Such analysis will facilitate the choice of the most conservative conditions for a flammability test. This paper is focused on a case study performed on wheat starch with the modified Hartmann tube. The dispersion process of the powder was studied with granulometric analyses performed in situ and high speed videos. Tests were performed with injections at gas pressure ranging from 3 to 6 bars and the evolution of the particle size distribution (PSD) was recorded at different ignition heights (5, 10 and 15 cm over the dispersion nozzle). The observations highlighted the presence of agglomeration/deagglomeration processes and dust segregation. Besides, a CFD simulation analysis was aimed at evaluating the impact of a set of parameters on the PSD and the local turbulence, which are closely linked to some flammability parameters. For this computational analysis, the CFD simulation was coupled with a collision treatment based on a Discrete Element Method (DEM) in order to consider the cohesive behavior of the combustible dust. Thus the results suggest performing the injection of the gases at approximately 5 bars for the flammability tests of wheat starch in order to obtain the finest PSD at a given ignition height. It is also shown that the finest PSD are obtained at 5 cm over the dispersion nozzle. However, the local instabilities and turbulence levels are so high during the first stages of the dispersion that the flame growth can be disturbed for short ignition delays. Moreover, the stabilization of the bulk of the dust cloud requires longer periods of time when the ignition sources are located at 15 cm. As a result, the recommended height to perform a flammability test is 10 cm in this case. Finally, this study proposes some tools that might improve the procedure of dust flammability testing.     

暴雨径流对非常规水源补给城市河流水质冲击研究

选择北运河流域典型非常规水源补给城市河流(凉水河)为研究对象,阐述暴雨径流对非常规水源补给城市河流水体物理化学特征的影响.结果表明,非暴雨期间,凉水河水体p H和DO平均值分别为7.67和3.88 mg·L-1;耗氧物质COD和氨氮(NH+4-N)平均质量浓度分别为47.41 mg·L-1和8.39 mg·L-1;富营养化元素总氮(TN)和总磷(TP)平均质量浓度分别为16.34 mg·L-1和1.45 mg·L-1.暴雨期间,雨水径流汇入收纳水体后,COD、NH+4-N、TP平均质量浓度明显上升,最高值分别达到108、14.24、3.02 mg·L-1.在空间分布上,COD、NH+4-N、TN和TP质量浓度变化趋势随土地利用类型变化特征趋于一致,从城镇区至农村区,均呈逐渐上升趋势.