气氛含氧量对DDT热处理特性的影响

滴滴涕属于有机氯农药,其所含成分DDTs在环境中难以降解,并具有生物毒性。利用高温管式炉研究气氛中含氧量对滴滴涕热处理特性的影响,为研发废弃滴滴涕高温热处理技术提供理论依据。实验结果表明,在600℃时,滴滴涕去除率最高为含氧量21%时的70.48%;在900℃条件下,当含氧量为21%时DDT去除率≥99%;在1 200℃条件下,当含氧量≥12%时DDT去除率≥99.9%。在滴滴涕热处理残渣中,o,p’-DDT占DDTs总量的比例在3个温度段中都随含氧量的增加而增长,DDT则都随含氧量增加而减少,且上述变化随温度升高而幅度加大。在尾气中,p,p’-DDE占DDTs总量的比例在3个温度段中都随含氧量增加而递增,在1 200℃条件下尤为明显。     

F-T合成技术生产替代燃料对环境的影响及对策

主要介绍了F-T合成柴油的特性,阐述了其作为清洁能源的优越性;利用生命周期清单分析方法,比较了以煤、生物质及天然气为原料采用F-T合成技术生产替代能源的工艺路线前提下,在提取生产、转化精炼、运输分配、最终用途燃烧、全部燃料链各阶段温室气体排放情况,提出了温室气体的减排对策。     

基于EGR的乙醇-生物柴油-柴油发动机排放性能

在单缸风冷四冲程直喷柴油发电机上,燃用柴油、生物柴油、10%乙醇-45%生物柴油-45%柴油（E10B45D45）和20%乙醇-40%生物柴油-40%柴油（E20B40D40）,采用16%、28% EGR率,测试并分析了经济性,NOx、HC和CO的排放性能和烟气的光吸收系数。研究表明：柴油的油耗最低,生物柴油次之,随着乙醇含量的增加,混合燃料的油耗增加;随着乙醇含量的增多,NOx排放量降低,与燃用柴油相比,E10B45D45和E20B40D40平均可降低约16.1%和30.2%;采用EGR可有效降低NOx排放,对应16%、28% EGR率,E10B45D45的NOx排放可平均降低19.3%和39.5%,E20B40D40平均降低10.7%和43.5%;随着乙醇含量的增多,HC排放量显著升高,对比于柴油,E10B45D45和E20B40D40分别升高了59.8%和172.1%;采用EGR后,HC排放增加;随乙醇含量的增加,CO排放也明显增大,对比于柴油,E10B45D45和E20B40D40分别升高了58.6%和131.1%;采用EGR后CO排放增加;各燃料中,柴油在小、中负荷烟气的光吸收系数最低,大负荷时却最高;不宜在小负荷时采用较高的乙醇掺混比和较大的EGR率。     

烟热分离系统砖瓦隧道窑的数值模拟及烟气含氧量影响因素分析

为降低砖瓦隧道窑烟气含氧量,使烟气中的污染物稳定达标排放,设计了正交实验并应用数值模拟方法对影响砖瓦隧道窑烟气含氧量的因素进行了分析;在此基础上,调整了相关参数并进行了现场运行测试及数值模拟方法的实测验证。结果表明：现场测试结果与数值模拟结果具有良好的一致性;降低排烟风机入口压力、急冷风机风量和冷却风机风量有利于降低烟气含氧量;以标况排烟风量为评价指标,各因素对烟气含氧量的影响程度依次为：排烟风机入口压力>急冷风机风量>余热风机入口压力>冷却风机风量。在隧道窑稳定运行情况下,仅通过调整排烟风机运行状态进行烟气含氧量控制实验,结果表明,烟气含氧量由调控前的18.24%降低至16.57%~17.12%,标准状态下烟气量由24 000 m³·h⁻¹降至19 000~20 000 m³·h⁻¹。在该隧道窑排烟风机运行状态优化调整后,已稳定运行6个月,且烟气含氧量稳定控制在18%以下。本研究结果可为隧道窑烟气含氧量控制及烟热分离系统的调控提供参考。     

载气含氧量及污染物浓度对土壤石油烃热脱附效率的影响

石油烃(TPHs)在土壤中难以降解,并具有生物毒性,异位热脱附(ESTD)在修复石油烃污染土壤方面极具应用潜力。采用实验室模拟异位热脱附装置,研究了热脱附载气含氧量及土壤石油烃污染浓度对可萃取石油烃(EPHs)中柴油段(DRO)和重油段(ORO)的5种组分去除率的影响。结果表明：在初始浓度为5 000~20 000 mg·kg⁻¹时,在20 min内的脱附率均不超过50%;当初始浓度增加到40 000 mg·kg⁻¹、脱附时间为20 min时脱附率可以达到68.2%。热脱附时间为50 min时,40 000 mg·kg⁻¹污染土壤的残余浓度为407.1 mg·kg⁻¹。DOR组分相同时间的脱附率随污染浓度的升高而升高,ORO组分在50 min之内不能完全脱附,脱附率随着污染物浓度上升会出现先增大后减小的趋势。在250 ℃时,DRO中3个组分的去除率均随着气氛含氧量的增加而呈现明显的增长趋势。在400 ℃条件下,ORO中2个组分分别在含氧量为12%和15%时达到最高的去除率。本研究结果可为ESTD技术修复不同浓度的石油烃污染土壤的工程设计参数提供参考。     

纺织行业水污染物排放量的关键影响要素研究

分析了2005—2012年纺织行业单位产品的用水量、主要水污染物排放强度和排放浓度的变化趋势,并采用灰色关联度分析方法,对各要素与行业主要水污染物排放量进行了关联分析。结果显示,2005—2012年中国纺织行业主要水污染物的排放强度显著下降,2012年COD和氨氮的排放强度分别为5.93、0.41kg/t,相比2005年分别下降了51.9%和39.7%。与纺织行业COD排放量变化最为密切的指标是单位产品的废水排放量、单位产品取水量与单位产品COD排放量,说明纺织行业生产工艺的提升对行业COD排放量的降低有较为密切的关系。与氨氮排放量变化最为密切的指标是单位企业产品产量、氨氮平均排放浓度与总量类指标,说明企业规模、末端治理工艺与氨氮排放量有较为密切的关系。     

公交车燃用B5生物柴油的非常规污染物排放特性及对区域大气污染物减排的作用

为推行区域大气污染联合防治并推广使用B5生物柴油,基于重型底盘测功机,采用C-WTVC循环,对比研究满足国Ⅳ、国Ⅴ排放标准的柴油公交车分别燃用国Ⅴ柴油、京Ⅵ柴油和B5生物柴油时的非常规污染物排放特性。结果表明：相比京Ⅵ柴油在采用B5生物柴油后,在不同耐久里程下的所有样车整体上的1,3-C4H6排放因子平均降低20.53%;C6H6排放因子平均降低7.67%;C7H8排放因子平均降低11.22%;HCHO排放因子平均降低14.92%;SO2排放因子平均降低6.09%。实验证明城市公交车在燃用B5生物柴油后的非常规污染物排放均降低。城市公交车推广使用B5生物柴油可有效净化大气质量,对区域大气污染物减排有着重要意义。     

砂对海水中溶解油的吸附及影响因素研究

以柴油污染的海水为对象，研究了砂对海水中溶解油的吸附作用及吸附的影响因素。结果表明，砂对溶解油的吸附符合Henry型吸附等温式，其吸附量随着砂粒粒径的减小、温度的降低和盐度的增加而增大。在影响吸附的3种因素中，粒径对吸附的影响最大。通过吸附热力学分析，推断砂对溶解油的吸附属于物理吸附。     

砂对海水中溶解油的吸附及影响因素研究

以柴油污染的海水为对象,研究了砂对海水中溶解油的吸附作用及吸附的影响因素.结果表明,砂对溶解油的吸附符合Henry型吸附等温式,其吸附量随着砂粒粒径的减小、温度的降低和盐度的增加而增大.在影响吸附的3种因素中,粒径对吸附的影响最大.通过吸附热力学分析,推断砂对溶解油的吸附属于物理吸附.     

脱硫石膏耦合微波对生产燃料乙醇厌氧消化污泥脱水性能的影响

为使污泥脱水后资源化农用,利用微波在不同功率（800、640和560 W）和时间（60、120和180 s）条件下,耦合脱硫石膏（2、4、6和8 g·L-1）对燃料乙醇厌氧消化污泥（ADSFE）脱水性能改善进行研究,探讨其脱水效果及相关机理。结果表明,最佳条件是脱硫石膏（6 g·L-1） 耦合微波（640 W,120 s）处理。在最佳处理条件下,污泥比阻（SRF）下降至1.05×1012 m·kg-1,与原污泥相比降低了87.5%,与单独加入脱硫石膏相比降低了77.80%,与单独微波调理相比降低了75.60%。此外,扫描电镜（SEM）表明耦合调理后的ADSFE形成致密且具有较大孔径的絮体, 易实现固液分离;热重（TG-DTG）曲线显示,脱水起始温度和热重峰明显前移。因此,脱硫石膏与微波协同作用调理ADSFE 时,脱水性能明显改善并优于单独调理的效果。同时,处理后污泥有机质含量满足有机肥制备原料要求。     

Bioethanol-gasoline fuel blends: exhaust emissions and morphological characterization of particulate from a moped engine

This study was aimed at evaluating the effects of gasoline-ethanol blends on the exhaust emissions in a catalyst-equipped four-stroke moped engine. The ethanol was blended with unleaded gasoline in at percentages (10, 15, and 20% v/v). The regulated pollutants and the particulate matter emissions were evaluated over the European ECE R47 driving cycle on the chassis dynamometer bench. Particulate matter was characterized in terms of total mass collected on filters and total number ofparticles in the range 7 nm-10 microm measured by electrical low-pressure impactor (ELPI). In addition, particle-phase polycyclic aromatic hydrocarbons (PAHs) emissions were evaluated to assess the health impact of the emitted particulate. Finally, an accurate morphological analysis was performed on the particulate by high-resolution transmission electron microscope (TEM) equipped with a digital image-processing/data-acquisition system. In general, CO emission reductions of 60-70% were obtained with 15 and 20% v/v ethanol blends, while the ethanol use did not reduce hydrocarbon (HC) and NOx emissions. No evident effect of ethanol on the particulate mass emissions and associated PAHs emissions was observed. Twenty-one PAHs were quantified in the particulate phase with emissions ranging from 26 to 35 microg/km and benzo[a]pyrene equivalent (BaPeq) emission factors from 2.2 to 4.1 microg/km. Both particulate matter and associated PAHs with higher carcinogenic risk were mainly emitted in the submicrometer size range (<0.1 microm). On the basis of the TEM observations, no relevant effect of the ethanol use on the particulate morphology was evidenced, showing aggregates composed ofprimary particles with mean diameters in the range 17.5-32.5 nm.     

Effects of fuel types and fuel sulfur content on the characteristics of particulate emissions in marine low-speed diesel engine

Environmental Science and Pollution Research - The emission of particulate matter from ships does great harm to human health and atmospheric environment. Sulfur emission regulations also affect...     

行驶速度对机动车尾气排放的影响

利用COPERTIV模型计算和车载尾气测量系统实测得到不同行驶速度下的机动车尾气排放因子,并分析不同车型不同排放标准等级车辆的行驶速度对排放的影响。调查研究北京市城区路网早高峰、平峰、晚高峰和夜间的车流量、车型构成、行驶速度,基于ArcGIS建立平均车速和行驶里程的网格分布数据库,并对比车速修正前后不同道路类型不同污染物的排放强度。结果表明,基于COPERT IV模型和车载测量系统计算的小客车NOx和HC排放因子随车速的变化趋势类似,均随车速的增加呈现U型分布;柴油公交车与柴油卡车NOx和HC排放因子随着车速的升高而减小。4个时间段平均车速大小排序为：夜间（44 km·h-1）> 晚高峰（34 km·h-1）> 平峰（32 km·h-1）> 早高峰（28 km·h-1）。车速修正后CO和HC的排放量上升,上升幅度分别为10.6%~11.8%和8.8%~9.2%,NOx和PM排放量下降,下降幅度分别为22.1%~23.3%和12.7%~13.5%。     

Effect of electrostatic precipitator on exhaust emissions in biodiesel fuelled CI engine

Environmental Science and Pollution Research - The exhaust emissions from the compression ignition engines are harmful to both human beings and the environment. After-treatment devices placed in...     

Polycyclic aromatic hydrocarbon exhaust emissions from different reformulated diesel fuels and engine operating conditions

The study of light-duty diesel engine exhaust emissions is important due to their impact on atmospheric chemistry and air pollution. In this study, both the gas and the particulate phase of fuel exhaust were analyzed to investigate the effects of diesel reformulation and engine operating parameters. The research was focused on polycyclic aromatic hydrocarbon (PAH) compounds on particulate phase due to their high toxicity. These were analyzed using a gas chromatography–mass spectrometry (GC–MS) methodology.Although PAH profiles changed for diesel fuels with low-sulfur content and different percentages of aromatic hydrocarbons (5–25%), no significant differences for total PAH concentrations were detected. However, rape oil methyl ester biodiesel showed a greater number of PAH compounds, but in lower concentrations (close to 50%) than the reformulated diesel fuels. In addition, four engine operating conditions were evaluated, and the results showed that, during cold start, higher concentrations were observed for high molecular weight PAHs than during idling cycle and that the acceleration cycles provided higher concentrations than the steady-state conditions. Correlations between particulate PAHs and gas phase products were also observed.The emission of PAH compounds from the incomplete combustion of diesel fuel depended greatly on the source of the fuel and the driving patterns.     

Effect of fuel aromatic content on PAH emission from a heavy-duty diesel engine

Polycyclic aromatic hydrocarbons (PAHs) emission tests for a heavy-duty diesel engine fueled with blend base diesel fuel by adding batch fractions of poly-aromatic and mono-aromatic hydrocarbons, Fluorene and Toluene, respectively, were simulated to five steady-state modes by a DC-current dynamometer with fully automatic control system. The main objective of this study is to investigate the effect of total aromatic content and poly-aromatic content in diesel fuels on PAH emission from the HDD engine exhaust under these steady-state modes. The results of this study revealed that adding 3% and 5% (fuel vol%) Fluorene in the diesel fuel increases the amount of total-PAH emission by 2.6 and 5.7 times, respectively and increases the amount of Fluorene emission by 52.9 and 152 times, respectively, than no additives. However, there was no significant variation of PAH emission by adding 10% (vol%) of Toluene. To regulate the content of poly-aromatic content in diesel fuel, in contrast to the total aromatic content, will be more suitable for the management of PAH emission.     

Study of Miller timing on exhaust emissions of a hydrotreated vegetable oil (HVO)-fueled diesel engine

The effect of intake valve closure (IVC) timing by utilizing Miller cycle and start of injection (SOI) on particulate matter (PM), particle number, and nitrogen oxide (NO_x) emissions was studied with a hydrotreated vegetable oil (HVO)-fueled nonroad diesel engine. HVO-fueled engine emissions, including aldehyde and polyaromatic hydrocarbon (PAH) emissions, were also compared with those emitted with fossil EN590 diesel fuel. At the engine standard settings, particle number and NO_x emissions decreased at all the studied load points (50%, 75%, and 100%) when the fuel was changed from EN590 to HVO. Adjusting IVC timing enabled a substantial decrease in NO_x emission and combined with SOI timing adjustment somewhat smaller decrease in both NO_x and particle emissions at IVC??50 and??70 °CA points. The HVO fuel decreased PAH emissions mainly due to the absence of aromatics. Aldehyde emissions were lower with the HVO fuel with medium (50%) load. At higher loads (75% and 100%), aldehyde emissions were slightly higher with the HVO fuel. However, the aldehyde emission levels were quite low, so no clear conclusions on the effect of fuel can be made. Overall, the study indicates that paraffinic HVO fuels are suitable for emission reduction with valve and injection timing adjustment and thus provide possibilities for engine manufacturers to meet the strictening emission limits.

Implications: NO_x and particle emissions are dominant emissions of diesel engines and vehicles. New, biobased paraffinic fuels and modern engine technologies have been reported to lower both of these emissions. In this study, even further reductions were achieved with engine valve adjustment combined with novel hydrotreated vegetable oil (HVO) diesel fuel. This study shows that new paraffinic fuels offer further possibilities to reduce engine exhaust emissions to meet the future emission limits.

Supplementary Materials: Supplementary materials are available for this paper. Go to the publisher's online edition of the Journal of the Air & Waste Management Association for a complete list of analysed PAH compounds.     

Real-time measurements of jet aircraft engine exhaust

Particulate-phase exhaust properties from two different types of ground-based jet aircraft engines--high-thrust and turboshaft--were studied with real-time instruments on a portable pallet and additional time-integrated sampling devices. The real-time instruments successfully characterized rapidly changing particulate mass, light absorption, and polycyclic aromatic hydrocarbon (PAH) content. The integrated measurements included particulate-size distributions, PAH, and carbon concentrations for an entire test run (i.e., "run-integrated" measurements). In all cases, the particle-size distributions showed single modes peaking at 20-40nm diameter. Measurements of exhaust from high-thrust F404 engines showed relatively low-light absorption compared with exhaust from a turboshaft engine. Particulate-phase PAH measurements generally varied in phase with both net particulate mass and with light-absorbing particulate concentrations. Unexplained response behavior sometimes occurred with the real-time PAH analyzer, although on average the real-time and integrated PAH methods agreed within the same order of magnitude found in earlier investigations.