综采工作面旋转风幕隔尘实验研究

为了研究综采工作面旋转风幕隔尘机理及其隔尘效率,对旋转风幕隔尘下的综采工作面粉尘浓度分布及其隔尘效率开展了模型实验研究。研究结果表明,(1)在相同工况下,旋转风幕对全尘和呼吸性粉尘的隔尘效率高于普通空气幕,且对呼吸性粉尘的隔尘优势更为明显;(2)出口风速对隔尘效果的影响较大,存在一个最佳的出口风速,在该风速下旋转风幕对全尘和呼吸性粉尘均保持较高的隔尘效率;(3)当出口风速低于最佳风速时,旋转风幕对全尘和呼吸性粉尘的隔尘效率均随着风速的增加而显著提高;当出口风速高于最佳风速时,随着出口风速的增加全尘隔尘效率不断下降,且呼吸性粉尘隔尘效率提升不明显;(4)旋转风幕对于不同粒径的粉尘的隔尘效率存在差异,随着粉尘粒径的增加,旋转风幕的隔尘效率不断下降。     

高风速复合式电收尘器的试验研究

应用"高风速"理论,将流体力学、电动力学、静电学有机结合设计出的高风速复合式电收尘器(HWSCESP)系统.试验以收尘效率作为收尘指标,以粉尘初始浓度、有效收尘面积、工作电压和系统风速为影响因素进行试验分析.结果表明,当粉尘初始浓度在45 g/m3,工作电压在47 kV,有效收尘面积为14.5 m2,系统风速为3.8 m/s时,收尘效率可达99.92%.从实验结果表明,HWSCESP是高效率、低成本的新型电收尘器.     

直筒式旋风脉冲静电除尘器性能研究

实验研究了电压、入口粉尘浓度和入口风速对直筒式旋风脉冲静电除尘器除尘效率的影响,测定了在不同入口风速下除尘器的分级效率.结果表明,脉冲供电能显著提高除尘器的除尘效率和分级效率,在脉冲电压为80 kV、入口粉尘质量浓度为5.0 g/m3N、入口风速为7～10 m/s时,除尘效率在99%以上,并在实验的基础上分析了脉冲供电下除尘器的除尘机理.     

大高差溜槽粉尘颗粒扩散运动规律数值模拟

为解决大型露天矿回填溜槽运输系统产生的粉尘污染问题,运用溜槽物料牵引流、落料诱导气流和剪切气流理论分析了溜槽工艺的粉尘析出机理。研究发现,溜槽运输系统粉尘的析出是诱导空气的尘化作用、剪切压缩尘化作用的结果,粉尘析出的主要影响因素包括物料的基本属性、运行速度及溜槽出口落差。基于气固两相流理论,利用数值模拟方法计算小空间粉尘颗粒的扩散规律和颗粒运动轨迹,结果显示溜槽系统粉尘粒径范围在0~100μm,物料流速度大于10m/s时,粉尘大部分被扬起,溜槽出口距离平台距离越大粉尘析出量越大。为制定多尺度、综合的粉尘防治措施提供必要的理论支撑与科学依据。     

基于FLUENT软件的综掘工作面粉尘运移规律研究

以某矿综掘工作面为研究背景,在现有实际条件下,采用长压短抽通风系统方式进行降尘。运用FLUENT软件对综掘巷道进行数值模拟,对研究区域粉尘运移规律进行分析。结果表明,粉尘浓度沿程先快速下降,在工作面5 m处出现峰值,10~40m处略有波动,40 m后趋于稳定。同时,用新设计的采尘工具对现场粉尘浓度进行实测,使得实测数据更准确,模拟和实测比拟结果基本一致,验证模型稳定性,得出了研究区域长压短抽通风系统作用下的粉尘运移规律,为综掘工作面粉尘的防治技术研究提供科学依据。     

钢铁厂露天堆料场挡风抑尘墙效果的数值模拟

对某钢铁厂露天堆料场设置挡风抑尘墙进行数值模拟研究,通过对动力阴影区覆盖面积的考察,分析了自然风速、墙高、墙开孔率及墙后建构筑物对挡风抑尘墙的挡风抑尘效果的影响.该钢铁厂露天堆料场设置防风抑尘墙的最佳几何尺寸是:墙长(L)为500 m,墙厚(d)为5 mm,墙高(H)为15～20 m,墙开孔率(k)为0.2～0.3,在主导风风速达到10 m/s以上的大风天气能够形成有效覆盖整个料场的动力阴影区,再配以合适的喷雾洒水或喷洒化学抑尘剂等其他抑尘手段就能够非常有效地抑制料场扬尘.     

输煤皮带巷运煤量对扬尘运移扩散影响的数值模拟

为了掌握输煤皮带巷运煤期间的扬尘分布规律,探索更好的除尘工艺,以某大型煤矿主斜输煤皮带巷为研究背景,构建三维模型,依据气固两相流理论,运用双流体模型对不同运煤量下的粉尘浓度三维分布规律进行数值模拟。结果表明:皮带运煤量的增加,增大了煤流与风流之间的摩擦面积及巷道断面风速,提高了扬尘强度,扩大了高浓度区域范围,显著增加了巷道中下部空间的粉尘污染程度;运煤量的增加对粉尘浓度的影响程度随着距皮带距离的增加而减小;在湿式除尘设计中,可通过自动喷雾系统与煤量监测之间的联动,提高除尘效果。     

静电除尘器内细微尘涡流现象的数值模拟

基于计算流体力学,以ANSYS软件中的FLUENT模块为平台模拟了粉尘粒径、烟气流速、电晕极电压和烟气含尘浓度对静电除尘器内细微尘涡流现象的影响。研究表明:随着粉尘粒径和烟气流速的增大,颗粒在静电除尘器内的合速度增大,粒子突破空气阻力维持原方向运动的能力增强,涡流的强度降低;随着电晕极电压和在一定范围内烟气含尘浓度的增加,高速流体区域与低速流体区域的速度差增大,涡流的强度会随之增加;继续增大烟气含尘浓度,导致静电除尘器内出现电晕封闭现象,"电风"逐步减弱,电场力大幅减小,粒子跟随烟气流出静电除尘器,涡流被大幅削弱或消失。根据以上规律,以相对均方根值为指标设计L~9(3~4)正交模拟,得出各因素对涡流影响程度由高到低分别为烟气流速、电晕极电压、含尘浓度、粉尘粒径。     

表面活性剂对叶面滞尘作用的影响

表面活性剂能够增强植物叶面滞尘能力,研究不同表面活性剂对植物滞尘能力的影响,对于利用植物防治粉尘污染有重要意义。以LAS、DTAB、AR和APG200为喷洒试剂,研究了8种植物吸附表面活性剂后滞留粉尘的重量、组分。结果表明,LAS浓度、植物种类、表面活性剂类型对滞尘量和面积比具有显著影响(P0.05);表面活性剂能够有效提高植物滞尘能力,LAS、DTAB效果优于生物型AR、APG200,且测试叶面滞尘量的变化与叶面接触角无明显关系;LAS使除朴树外所有植物的滞尘能力增加的浓度为0.2 g/L,而对滞留粉尘组分改变较大的浓度为0.5 g/L;此外,表面活性剂能改变滞留粉尘的组分,但不具有明显的规律性,粉尘的遮光比变化趋势与叶面滞尘量基本相似。     

破碎站粉尘逸散规律及降尘技术的数值模拟及其应用

针对露天矿破碎站粉尘污染严重、治理技术中存在的缺陷,提出了超声波雾化喷雾降尘技术。以平朔安家岭煤矿为例,根据破碎站区域粉尘污染情况,应用数学模型对破碎站粉尘逸散规律进行解算,将模拟结果与现场实测数据对比,确定对卸载坑采用150~300μm雾滴粒径和对破碎机各产尘点采用1~10μm雾滴粒径的机体梁上外喷雾方式,通过对采取治理方案后破碎站粉尘浓度逸散的数值模拟和现场实际应用后的测试数据,显示全尘和呼吸性粉尘降尘效率分别达到94%和82%。结果表明,超声波喷雾降尘技术能有效降低破碎站粉尘浓度,保障了作业人员工作环境和安全。     

Field and laboratory studies of the fate and enantiomeric enrichment of venlafaxine and O-desmethylvenlafaxine under aerobic and anaerobic conditions

The stereoselectivity of R,S-venlafaxine and its metabolites R,S-O-desmethylvenlafaxine, N-desmethylvenlafaxine, O,N-didesmethylvenlafaxine, N,N-didesmethylvenlafaxine and tridesmethylvenlafaxine was studied in three processes: (i) anaerobic and aerobic laboratory scale tests; (ii) six wastewater treatment plants (WWTPs) operating under different conditions; and (iii) a variety of wastewater treatments including conventional activated sludge, natural attenuation along a receiving river stream and storage in operational and seasonal reservoirs. In the laboratory and field studies, the degradation of the venlafaxine yielded O-desmethylvenalfaxine as the dominant metabolite under aerobic and anaerobic conditions. Venlafaxine was almost exclusively converted to O-desmethylvenlafaxine under anaerobic conditions, but only a fraction of the drug was transformed to O-desmethylvenlafaxine under aerobic conditions. Degradation of venlafaxine involved only small stereoisomeric selectivity. In contrast, the degradation of O-desmethylvenlafaxine yielded remarkable S to R enrichment under aerobic conditions but none under anaerobic conditions. Determination of venlafaxine and its metabolites in the WWTPs agreed well with the stereoselectivity observed in the laboratory studies. Our results suggest that the levels of the drug and its metabolites and the stereoisomeric enrichment of the metabolite and its parent drug can be used for source tracking and for discrimination between domestic and nondomestic wastewater pollution. This was indeed demonstrated in the investigations carried out at the Jerusalem WWTP.     

剩余污泥浓缩脱水投药量优化和模型建立

应用高分子阳离子絮凝剂（CPF-100）和聚丙烯酰胺（PAM）对污水厂剩余污泥进行浓缩脱水实验，研究表明：CPF-100的浓缩脱水效果优于PAM；当CPF-00投加量为1．16‰时，污泥沉降性能改善程度为37．51％；且在CPF-100投加量逐渐增大的初始阶段，污泥沉降性能改善程度随投加量的增加而增大，但CPF-100投加量也不宜过大，当CPF-100投加量超过1．16‰后，反而会使浓缩脱水效果变差。同时，建立了污泥沉降性能改善程度与絮凝剂CPF-100投加量、沉降时间之间的数学模型，其能较好地反映污水厂剩余污泥的浓缩脱水效果。     

骆马湖富营养化和生态状况调查与评价

为了了解骆马湖水质状况，在2005年对骆马湖富营养化状态和生态特性进行了调查，并结合“十五”期间的监测资料进行了分析。2005年骆马湖水体中总氮和总磷的平均值超《地表水环境质量标准》（GB3838-2002）中Ⅲ类，超标情况分别为0．78倍和0．54倍，达到湖库特定项目Ⅳ类水标准，骆马湖处于轻度富营养化状态。对骆马湖生态特征分析表明，由于该湖泊的形态以及“藻型浊水状态”和“泥沙型浊水状态”交替出现，遏制了湖水从高营养盐含量向全面富营养化状态演变，保障了底栖动物的良好生长环境，从而形成了骆马湖独特的环境生态平衡。     

Copper-catalyzed chlorination and condensation of acetylene and dichloroacetylene

The chlorination and condensation of acetylene at low temperatures is demonstrated using copper chlorides as chlorinated agents coated to model borosilicate surfaces. Experiments with and without both a chlorine source and borosilicate surfaces indicate the absence of gas-phase and gas-surface reactions. Chlorination and condensation occur only in the presence of the copper catalyst. C₂ through C₈ organic products were observed in the effluent; PCDD/F were only observed from extraction of the borosilicate surfaces. A global reaction model is proposed that is consistent with the observed product distributions. Similar experiments with dichloroacetylene indicate greater reactivity in the absence of the copper catalyst. Reaction is observed in the gas-phase and in the presence of borosilicate surfaces at low temperatures. The formation of hexachlorobenzene is only observed in the presence of a copper catalyst. PCDD/F were only observed from extraction of the borosilicate surfaces. A global reaction model is proposed for the formation of hexachlorobenzene from dichloroacetylene.     

Aerobic and anaerobic degradation of profluralin and trifluralin

Abstract

The degradation of profluralin [N‐(cyclopropylmethyl)‐α,α,α‐trifluoro‐2,6‐dinitro‐N‐propyl‐]p‐toluidine] and trifluralin (α,α,α‐trifluoro‐2,6‐dinitro‐N,N‐dipropyl‐p‐toluidine) was studied under aerobic and anaerobic soil conditions. Three soils (Goldsboro loamy sand, Cecil loamy sand, Drummer clay loam) were each treated with 1 ppmw herbicide; anaerobic conditions were maintained by flooding. Soil samples were extracted monthly and subjected to TLC analysis. No degradation was detected in sterile controls. Aerobic degradation of both herbicides was greatest in the Cecil loamy sand soil over the entire incubation period. Degradation of profluralin in Cecil soil under aerobic conditions was 86 percent after 4 months with three products detected; 83 percent of the trifluralin was degraded with two products detected. Anaerobic degradation accounted for 72 percent of the profluralin and 78 percent of the trifluralin after 4 months. Degradation of both herbicides increased with incubation time for the first 3 months and decreased slightly thereafter. Generally there was more extensive degradation (percent and in number of products formed) of profluralin than trifluralin under the conditions tested. More degradation products were detected for both herbicides under aerobic conditions than under anaerobic conditions.     

Sources and distribution of polychlorinated-dibenzo-p-dioxins and -dibenzofurans in soil and sediment from the Yellow Sea region of China and Korea

Polychlorinated-dibenzo-p-dioxins and -dibenzofurans (PCDD/Fs) were measured in soils and sediments from the Yellow Sea region. Korean soils and sediments mostly contained detectable PCDD/Fs and showed a widespread distribution among locations. Soil and sedimentary PCDD/Fs from China were comparable to or less than those in Korea. The patterns of relative concentrations of individual congeners in soils were different between the two countries, but similar in sediments. Sources of PCDD/Fs in China and Korea were found to be independent of each other and their distributions reflected matrix-dependent accumulation. Spatial distribution indicated some point sources in Korea while Chinese sources were more widespread and diffuse. PCDD/Fs measured in the coastal areas of the Yellow Sea were comparable to or less than those previously reported in for eastern Asia. However, ∑TEQs in soils and sediments were near to or, in some cases exceeded environmental quality guidelines.     

Quantification of carbamazepine and atrazine and screening of suspect organic contaminants in surface and drinking waters

A new approach for the identification of suspect trace organic contaminants in drinking and surface waters is presented. Samples were initially analyzed using a target determination method for two contamination tracers, carbamazepine (CBZ) and atrazine (ATZ). This method used offline solid-phase extraction and online solid-phase extraction techniques coupled to liquid chromatography-triple quadrupole mass spectrometry to accelerate the sample preparation process and improve method performance. CBZ and ATZ were found respectively in 31% and 56% of the samples, and concentrations were usually <20 ng L⁻¹. These samples were re-analyzed with a similar method on a quadrupole time-of-flight mass spectrometer to identify suspect contaminants by means of exact mass measurements and isotope patterns. A database of 264 common organic contaminants was built and used in conjunction with a Molecular Feature algorithm to identify the presence of these substances in drinking and surface water collected from different sources at various locations across Canada. Several organic contaminants were identified in the samples, but only the presence of caffeine, desethylatrazine, simazine and venlafaxine could be verified by comparison to pure standards. The presence of desethylatrazine was also confirmed by MS/MS experiments. These results suggest that target analysis for tracers of organic contamination may be a helpful tool to prioritize samples which should be further screened for suspect contaminants. This study also shows that the combination of separation techniques (offline and online SPE, LC) contribute to advance the applicability of high-resolution mass spectrometry for the identification of trace organic contaminants by accelerating the preparation step, reducing complexity and increasing analyte concentrations for optimal detection.     

Effects of compositional heterogeneity and nanoporosity of raw and treated biomass-generated soot on adsorption and absorption of organic contaminants

A biomass-generated soot was sequentially treated by HCl-HF solution, organic solvent, and oxidative acid to remove ash, extractable native organic matter (EOM), and amorphous carbon. The compositional heterogeneity and nano-structure of the untreated and treated soot samples were characterized by elemental analysis, thermal gravimetric analysis, BET-N₂ surface area, and electron microscopic analysis. Sorption properties of polar and nonpolar organic pollutants onto the soot samples were compared, and individual contributions of adsorption and absorption were quantified. The sorption isotherms for raw sample were practically linear, while were nonlinear for the pretreated-soot. The removal of EOM enhanced adsorption and reduced absorption, indicating that EOM served as a partitioning phase and simultaneously masked the adsorptive sites. By drastic-oxidation, the outer amorphous carbon and the inner disordered core of the soot particles were completely removed, and a fullerene-like nanoporous structure (aromatic shell) was created, which promoted additional π-π interaction between phenanthrene and the soot.     

Sorption and Desorption Behavior of Chloroanilines and Chlorophenols on Montmorillonite and Kaolinite

The bioavailability of pollutants, pesticides and/or their degradation products in soil depends on the strength of their sorption by the different soil components, particularly by the clay minerals. This study reports the sorption-desorption behavior of the environmentally hazardous industrial pollutants and certain pesticides degradation products, 3-chloroaniline, 3,4-dichloroaniline, 2,4,6-trichloroaniline, 4-chlorophenol, 2,4-dichlorophenol and 2,4,6-trichlorophenol on the reference clays kaolinite KGa-1 and Na-montmorillonite SWy-l. In batch studies, 2.0 g of clay were equilibrated with 100.0 mL solutions of each chemical at concentrations ranging from 10.0 to 200.0 mg/L. The uptake of the compounds was deduced from the results of HPLC-UV-Vis analysis. The lipophilic species were best retained by both clay materials. The most lipophilic chemical used in the study, 2,4,6-trichloroaniline, was also the most strongly retained, with sorption of up to 8 mg/g. In desorption experiments, which also relied on HPLC-UV-Vis technique, 2,4,6-trichloroaniline was the least desorbed from montmorillonite. However, on kaolinite all of the compounds under study were irreversibly retained. The experimental data have been modelled according to the Langmuir and Freundlich isotherms. A hypothesis is proposed concerning the sorption mechanism and potential applications of the findings in remediation strategies have been suggested.     

Persistence and dissipation kinetics of trifloxystrobin and tebuconazole in onion and soil

The persistence and dissipation kinetics of trifloxystrobin and tebuconazole on onion were studied after application of their combination formulation at a standard and double dose of 75 + 150 and 150 + 300 g a.i. ha^?1. The fungicides were extracted with acetone, cleaned-up using activated charcoal (trifloxystrobin) and neutral alumina (tebuconazole). Analysis was carried out by gas chromatograph (GC) and confirmed by gas chromatograph mass spectrometry (GC-MS). The recovery was above 80% and limit of quantification (LOQ) 0.05 mg kg^?1 for both fungicides. Initial residue deposits of trifloxystrobin were 0.68 and 1.01 mg kg^?1 and tebuconazole 0.673 and 1.95 mg kg^?1 from standard and double dose treatments, respectively. Dissipation of the fungicides followed first-order kinetics and the half life of degradation was 6–6.6 days. Matured onion bulb (and field soil) harvested after 30 days was free from fungicide residues. These findings suggest recommended safe pre-harvest interval (PHI) of 14 and 25 days for spring onion consumption after treatment of Nativo 75 WG at the standard and double doses, respectively. Matured onion bulbs at harvest were free from fungicide residues.