CO2-超细水雾对瓦斯/煤尘爆炸抑制特性研究

为了解CO2-超细水雾对瓦斯/煤尘爆炸抑制特性，用自行搭建的实验系统，从超压、火焰传播速度和火焰结构3个方面研究了CO2-超细水雾形成的气液两相介质对9.5%瓦斯/煤尘复合体系爆炸的抑爆效果、影响因素与原因。研究结果表明:随着CO2体积分数和超细水雾质量浓度的增加，爆炸火焰最大传播速度、爆炸超压峰值均出现明显下降，火焰到达泄爆口时间显著延迟；尤其当CO2体积分数达到14%与超细水雾的共同抑爆效果凸显，瓦斯/煤尘复合体系爆炸超压的“震荡平台”消失，同时火焰结构呈现“整体孔隙化”。所得结论为煤矿井下高效防爆抑爆技术进行了完善和增强。     

适应低排放的电除尘技术探讨

针对高标准的排放要求以及将进一步提高的排放标准,对电除尘器是否能满足目前的排放标准和低排放要求进行了研究。通过对国内110个机组配套电除尘器实际应用情况调查和国外燃煤机组电除尘器应用分析,客观地评价了电除尘器对国内煤种的适应性,指出移动电极式电除尘器、双极异距电流体微粒聚合器、烟气调质、湿式电除尘器、低低温电除尘器等新技术的发展和综合应用是满足30mg/m3低排放标要求的最佳选择。     

新型气流剪切错流旋转填料床的综合性能评判

针对旋转填料床除尘效率低和运行能耗高的问题，通过改变上旋转填料环填料（上填料）和下旋转填料环填料（下填料）的孔隙率，增加填料环直径形成填料床壁面外突实现设备优化，研究超重力因子和气速对气流剪切错流旋转填料床（GSC-RPB）和新型气流剪切错流旋转填料床（NGSC-RPB）的影响，并提出应用品质因子评判填料床综合性能的方法。实验结果表明:优化前后旋转填料床的除尘效率和气相压力随着气速和超重力因子的增加而增加；NGSC-RPB的除尘效率较GSC-RPB有显著提高，NGSC-RPB的气相压降则略有降低；在达到国家超低排放浓度标准即5 mg/m3的前提下，通过对品质因子的分析可知，NGSC-RPB的综合性能有所提高，在气速为1.3 m/s，超重力因子为90~120时NGSC-RPB的综合性能最优。     

西安市表层土壤和地表灰尘理化性质分析

以西安城市表层土壤和地表灰尘为研究对象,分析其基本理化指标。结果表明,西安市表层土壤pH值的变化范围是7.65~8.54,属弱碱性。地表灰尘pH值的变化范围是6.59~11.19,属碱性。表层土壤的低频磁化率和高频磁化率均值分别为1.55×10^-6 m^3/kg和1.46×10^-6 m^3/kg,频率磁化率均值为6.7%。地表灰尘的低频磁化率和高频磁化率均值分别为5.50×10^-6 m^3/kg和4.84×10^-6 m^3/kg,频率磁化率均值为1.88%。表层土壤和地表灰尘中总有机碳均值分别为1.31%和3.97%。西安城市表层土壤和地表灰尘均主要以粉粒为主,且二者各理化性质之间均有一定的相关性。     

济南地区一次沙尘过程的激光雷达观测分析

利用微脉冲激光雷达探测技术,结合常规污染物监测以及PM_(2.5)化学组分监测数据,对2017年5月影响济南地区的一次沙尘天气过程进行分析。结果表明:5月4日12:00沙尘天气开始影响济南市,PM_(10)小时浓度大幅升高,至5月5日13:00,PM_(10)小时浓度达到峰值(质量浓度953μg/m~3)。沙尘过境期间近地面1 500 m以下形成消光系数和退偏比极大区,其中5月5日11:00—13:00,300 m处退偏比平均高达0. 19,非球形特性显著。沙尘天气过程中Mg~(2+)组分、Ca~(2+)组分增幅最为明显。后向轨迹模型HYSPLIT显示,此次沙尘起源于内蒙古中西部地区,沿高空西北方向传输至济南地区。     

Analysis of herbicide residues by gas chromatography

The extraction and clean‐up, and gas Chromatographic conditions for the detection and determination of herbicides, their metabolites and related compounds are reviewed. The literature material is examined critically in the text and presented in tabular form for quick reference. The section dealing with extraction/clean‐up techniques is sub‐divided with respect to water, soil, plant material, animal, fish and micro‐organisms. Under eight herbicide group headings the important gas Chromatographic parameters such as stationary phase, support phase, column temperature and mode of detection are tabulated. Also tabulated are the application of various detectors to herbicide analyses and limits of detection where information was available. Most commonly used liquid and support phases are listed and their frequency of use given. Different aspects of derivative formation used for the positive identification and quantitation of herbicides are discussed with emphasis on esterification, alkylation and silylation. Other important conversion techniques are outlined, particularly those associated with enhancement of sensitivity e.g. bromination, iodination, dinitrophenylation etc. Efforts that have been made towards general and automated analytical methods are discussed.     

环鄱阳湖区地表尘土重金属污染及健康风险评价

通过2010年4月采集环鄱阳湖区地表尘土样品,对其重金属污染物进行分析研究,并运用美国环保局推荐的健康风险评价模型对所引起的健康风险做了初步评价。结果表明,地表尘土中Cd、Cr、Cu、Pb、Zn平均含量分别为0.909、74.64、78.37、78.33、213.62 mg/kg,5种重金属平均含量均高于江西土壤背景值。重金属非致癌风险Pb>Cr>Cu>Cd>Zn,均小于非致癌风险阈值1,对人体不会造成健康危害;致癌重金属致癌风险Cr>Cd,均低于癌症风险阈值,表明不具有致癌风险。暴露模型计算表明,重金属慢性每日平均暴露量为手-口接触摄入量>皮肤吸收量>吸入空气量,经手-口直接摄入是地表尘土暴露风险的主要途径。     

烟气和粉尘性质对除尘效率影响的仿真研究

应用欧拉-拉格朗日多相流模型对影响电除尘器内部气流分布的烟气含尘浓度、烟气湿度、粉尘粒径及真密度等因素进行了数值仿真。分析了烟气和粉尘性质对除尘效率的影响。由于在仿真过程中考虑了烟气特性和粉尘性质等因素,不仅可获得各因素对气流分布均匀性的影响,而且仿真结果更能反映电除尘器气流分布的实际情况。提出的烟气和粉尘性质仿真方法可以为电除尘器除尘效率分析提供新的途径。     

煤油共生矿区含油煤尘云最低着火温度试验研究

为研究煤油共生矿区含油煤尘最低着火温度的变化规律，选取3种含油浓度不同的煤样，采用粉尘云最低着火温度测定系统，研究含油煤尘云最低着火温度随含油浓度、喷尘压力及煤尘质量的变化规律。研究结果表明:含油煤尘的最低着火温度较不含油煤尘显著降低，且随着煤尘含油浓度的增加，煤尘中挥发分含量增多，煤尘云最低着火温度降低，爆炸危险性增强；低含油浓度煤尘，煤尘受原油挥发分影响较大，在含油浓度为5.7%，4.3%且质量浓度为1364~4550 g/m3时煤尘云最低着火温度随喷尘压力的增大呈先增大后减小的变化趋势，在5.7%，4.3%含油浓度且喷尘压力为0.05 MPa时煤尘MIT随煤尘质量浓度增加先降低后缓慢升高。高含油浓度煤尘，受煤尘团聚现象影响较大，煤尘云最低着火温度随喷尘压力的增加而升高，随煤尘质量的增加呈先减小后增大再缓慢减小的变化规律。     

Observations of microscopic characteristics of post-explosion coal dust samples

To reveal the microscopic characteristics of the post-explosion coal dust samples, coal dust explosion tests were performed in a 20 L spherical vessel. The explosion characteristic parameters, such as the maximum pressure (P_max), the maximum rate of pressure rise ((dP/dt)_max), ignition time (t) and the deflagration index (K_St) were recorded. Meanwhile, the post-explosion dust samples were collected and analyzed. The research efforts include particle size distribution analysis, SEM analysis and FTIR analysis of dust samples before and after the explosion. The particle size range of post-explosion dust samples became wider according to the mass percent analysis. The microscopic appearance of samples in same particle size range showed some similarity. The porous structure of dust samples was observed by improving the SEM magnification. The chemical structure of dust samples before and after explosion was analyzed by FTIR.