车用柴油机燃用棕榈生物柴油的颗粒物排放特性研究

在满足国Ⅳ排放法规的车用柴油机上研究了燃用不同掺混体积比例的棕榈油生物柴油的颗粒物排放特性.试验中棕榈油生物柴油的掺混比例分别为0%、10%、20%、50%和100%,采用DMS500型快速颗粒光谱仪测试分析了发动机在外特性和负荷特性时的颗粒物数量浓度、质量浓度及粒径分布.研究结果表明:随生物柴油掺混比例的增加,颗粒物质量浓度降低.燃用生物柴油后颗粒物的数量浓度在大负荷明显降低,中小负荷呈升高趋势.生物柴油的排气颗粒物呈核态和凝聚态的双峰分布特征,核态数量浓度所占比例高于柴油,凝聚态的质量浓度所占比例略低于柴油.生物柴油颗粒物的几何平均直径小于柴油.     

Removal of high concentrations of polycyclic aromatic hydrocarbons from contaminated soil by biodiesel

Solubilizing experiments were carried out to evaluate the ability of biodiesel to remove polycyclic aromatic hydrocarbons (PAHs) from highly contaminated manufactured gas plant (MGP) and PAHs spiked soils with hydroxypropyl-β-cyclodextrin (HPCD) and tween 80 as comparisons. Biodiesel displayed the highest solubilities of phenanthrene (420.7 mg·L⁻¹), pyrene (541.0 mg·L⁻¹), and benzo(a)pyrene (436.3 mg·L⁻¹). These corresponded to several fold increases relative to 10% HPCD and tween 80. Biodiesel showed a good efficiency for PAH removal from the spiked and MGP soils for both low molecular weight and high molecular weight PAHs at high concentrations. Biodiesel was the best agent for PAH removal from the spiked soils as compared with HPCD and tween 80; as over 77.9% of individual PAH were removed by biodiesel. Tween 80 also showed comparable capability with biodiesel for PAH solubilization at a concentration of 10% for the spiked soils. Biodiesel solubilized a wider range of PAHs as compared to HPCD and tween 80 for the MPG soils. At PAH concentrations of 229.6 and 996.9 mg·kg⁻¹, biodiesel showed obvious advantage over the 10% HPCD and tween 80, because it removed higher than 80% of total PAH. In this study, a significant difference between PAH removals from the spiked and field MGP soils was observed; PAH removals from the MGP soil by HPCD and tween 80 were much lower than those from the spiked soil. These results demonstrate that the potential for utilizing biodiesel for remediation of highly PAH-contaminated soil has been established.     

国Ⅴ公交车燃用生物柴油的颗粒物碳质组分排放特性

以一辆国Ⅴ柴油公交车为研究对象,在重型底盘测功机上运行中国典型城市公交循环,研究了纯柴油（D100）,体积混合比例分别为5%,10%和20%餐厨废弃油脂制生物柴油-柴油混合燃料（即B5,B10,B20）的颗粒物（PM）碳质组分排放特性.结果表明：国Ⅴ柴油公交车尾气颗粒物碳质组分包括有机碳（OC）和元素碳（EC）,OC占73%~82%,OC的主要组分是OC2和OC3,生物柴油对车辆尾气颗粒物OC组成比例没有影响;随着生物柴油混合比例的增加,公交车尾气颗粒物OC和OC+EC排放呈降低的趋势,EC排放增加,且B10的OC排放较高;PM_0.05~0.1,PM_0.1~0.5,PM_0.5~2.5,PM_2.5~18 4个粒径段颗粒物中,PM_0.1~0.5的OC和EC排放最高,PM_2.5~18的EC排放几乎为零,生物柴油可改善公交车尾气超细颗粒（PM_0.05~0.1）的OC排放,对公交尾气颗粒物EC排放基本没有影响;公交使用生物柴油混合燃料尾气颗粒物OC/EC减小,且PM_0.05~0.1和PM_0.5~2.5OC/EC降低幅度明显,对大气二次气溶胶的影响减弱.     

EGR率对农用单缸柴油机燃用生物柴油的NOx与PM排放特性影响分析

单缸柴油机作为小型农用机械不可或缺的动力源,在使用过程中会产生大量污染物.其中氮氧化合物（NO_x）和颗粒（PM）是气溶胶的主要组成部分,对大气环境造成了严重污染.为有效改善农用单缸柴油机NO_x和PM排放,本研究通过添加生物柴油对柴油进行改质以及采用机内EGR净化技术两种方案,测量了柴油机分别燃用柴油B0,生物柴油调合燃料B20、B50在不同EGR率下的NO_x和PM排放.结果表明,采用EGR技术能够明显改善柴油机的NO_x排放,但同时会引起碳烟排放的增加.通过在柴油中添加生物柴油能够在一定程度上降低碳烟排放,其中高负荷、大EGR率条件下的改善最为明显.在2000 r·min^-1、75%负荷,EGR率为30%时,燃用B50的碳烟排放与燃用B0相比降低了47.3%.总体上柴油中添加生物柴油与EGR技术共同作用能够有效降低柴油机高负荷工况时的颗粒排放总数量.     

船舶燃用B10餐厨废弃油脂制生物柴油排放测试与分析

利用便携式排放测试系统（PEMS）,对一艘内河船舶燃用B10餐厨废弃油脂制生物柴油（生物柴油:柴油为1:9,体积比）进行实际工况排放测试。出港和进港工况下,CO、THC、NO_x和PM瞬态排放速率波动明显,巡航工况下,CO、THC和PM瞬态排放速率较稳定,NO_x排放随空气流量变化而在一定范围内波动;同燃用纯柴油时气态物和颗粒物排放相比,船舶燃用B10生物柴油时,在出港、巡航和进港工况,CO排放速率下降了20.37%、24.39%和6.05%,THC下降了8.2%、8.13%和25.23%,PM下降了53.11%、22.38%和36.55%,PN下降了14.17%、18.75%和46.47%;在出港和进港工况,NO_x排放速率下降了54.28%和40.39%,在巡航工况,NO_x上升了10.45%;燃用2种燃油排放颗粒物均随粒径呈双峰分布,峰值粒径大致相同,燃用B10生物柴油时核态颗粒物数量下降明显。试验表明,船舶燃用B10生物柴油能有效降低气态物和颗粒物排放。     

柴油轿车颗粒多环芳烃的排放特性

以一辆柴油轿车为研究样车,分别使用纯柴油、生物柴油掺混比例为10%的B10燃油,进行了NEDC整车循环工况试验,测取了该车HC、CO、NOx、颗粒等法规限制的排放,利用气相色谱-质谱法对采集的排气颗粒样品进行了分析,重点研究了颗粒中多环芳烃的排放特性.结果表明,与柴油相比,燃用B10燃油的HC、CO、NOx和颗粒等常规排放均有所降低;两种燃料产生的颗粒多环芳烃排放中均以荧蒽和芘最多,与纯柴油相比,燃用B10燃油产生的低环数PAHs排放略有增加,中高环数的PAHs排放降幅明显.苯并[a]芘等效毒性分析结果显示燃用B10燃油的BEQs值比纯柴油降低了21.6%,表明柴油轿车燃用生物柴油后,排气颗粒的多环芳烃毒性有所下降.     

废食用油生物柴油的制备及其掺烧时的动力与排放特性

为了查明生物柴油对环境的影响以及废食用油制备的生物柴油对发动机性能和排放特性的影响,研究了生物柴油环境生命周期评价及其对环境的影响以及废食用油生物柴油的生产工艺流程,即甲醇与废食用油在催化剂作用下发生酯交换反应生产出生物柴油.所制备的生物柴油和柴油,按20%和50%掺混后在2台车用增压直喷式柴油机上进行了台架动力和排放特性的测试.试验结果表明,与柴油相比,掺混燃料的动力性和油耗率分别约有3%的下降和8%的上升,烟度、HC、CO和PM排放降低幅度最大分别达65%、11%、33%和13%,而NO_x排放有不同程度的上升.本研究表明,发动机燃用低比例的生物柴油掺混燃料,在发动机不作任何改动和调整时,可以在经济性、动力性和排放等方面取得令人满意的综合结果.     

Emissions of particulate matter and associated polycyclic aromatic hydrocarbons from agricultural diesel engine fueled with degummed, deacidified mixed crude palm oil blends

Mixed crude palm oil(MCPO),the mixture of palm fiber oil and palm kernel oil,has become of great interest as a renewable energy source.It can be easily extracted from whole dried palm fruits.In the present work,the degummed,deacidified MCPO was blended in petroleum diesel at portions of 30% and 40% by volume and then tested in agricultural diesel engines for long term usage.The particulates from the exhaust of the engines were collected every 500 hr using a four-stage cascade air sampler.The 50% cut-off aerodynamic diameters for the first three stages were 10,2.5 and 1μm,while the last stage collected all particles smaller than 1μm.Sixteen particle bounded polycyclic aromatic hydrocarbons(PAHs) were analyzed using a high performance liquid chromatography.The results indicated that the size distribution of particulate matter was in the accumulation mode and the pattern of total PAHs associated with fine-particles(< 1μm) showed a dominance of larger molecular weight PAHs(4-6 aromatic rings),especially pyrene.The mass median diameter,PM and total PAH concentrations decreased when increasing the palm oil content,but increased when the running hours of the engine were increased.In addition,Commercial petroleum diesel(PB0) gave the highest value of carcinogenic potency equivalent(BaP eq) for all particle size ranges.As the palm oil was increased,the BaP eq decreased gradually.Therefore the degummed-deacidified MCPO blends are recommended for diesel substitute.     

Exposure measurement, risk assessment and source identification for exposure of traffic assistants to particle-bound PAHs in Tianjin, China

To investigate the levels of exposure to particulate-bound polycyclic aromatic hydrocarbon(PAH) and to estimate the risk these levels pose to traffic assistants(TAs) in Tianjin(a megacity in North China), a measurement campaign(33 all-day exposure samples, 25 occupational-exposure samples and 10 indoor samples) was conducted to characterize the TAs' exposure to PAHs, assess the cancer risk and identify the potential sources of exposure. The average total exposure concentration of 14 PAHs was approximately 2871 ± 928 ng/m3(on-duty), and 1622 ± 457 ng/m3(all-day). The indoor PAHs level was 1257 ± 107 ng/m3. After 8000 Monte Carlo simulations, the cancer risk resulting from exposure to PAHs was found to be approximately 1.05 × 10-4. A multivariate analysis was applied to identify the potential sources, and the results showed that, in addition to vehicle exhaust, coal combustion and cooking fumes were also another two important contributors to personal PAH exposure. The diagnostic ratios of PAH compounds agree with the source apportionment results derived from principal component analysis.     

室内外PM10中多环芳烃相关关系及来源分析

为研究室内外PM10中多环芳烃相关性和来源特征,于2009年非采暖季、采暖季在天津市某小区36位住户室内和室外进行PM10膜采样,并分析其中12种PAHs浓度.结果表明,非采暖季较采暖季更为良好的室内外通风性,导致非采暖季室内外PM10中PAHs浓度没有显著差异(P>0.05),而采暖季室内PM10中PAHs浓度显著小于室外浓度;非采暖季室内外PM10中各PAHs占总PAHs的质量百分比基本一致,而采暖季其室内外质量百分比有明显不同;采暖季和非采暖季室内外PM10中PAHs的I/O平均值均低于1,但采暖季I/O值小于非采暖季. 对参与者的时间活动模式分析表明,在采暖季和非采暖季,室内吸烟、清洁活动以及烹饪对室内PM10中PAHs浓度变化均没有显著影响(P>0.05). 室内外PAHs浓度线性回归分析表明,室内PM10中5~7环PAHs主要受到室外源的影响,2~4环PAHs主要受到室内源的影响,非采暖季和采暖季室内外PM10中总PAHs的有效穿透因子分别为0.73和0.51. 通过特征比值法对PM10中PAHs来源进行解析得出,燃煤源、柴油机动车是其主要来源.     

A comparative study of particle size distribution from two oxygenated fuels and diesel fuel

Oxygenated fuels are known to reduce particulate matter (PM) emissions from diesel engines. In this study, 100% soy methyl ester (SME) biodiesel fuel (B100) and a blend of 10% acetal denoted by A-diesel with diesel fuel were tested as oxygenated fuels. Particle size and number distributions from a diesel engine fueled with oxygenated fuels and base diesel fuel were measured using an Electrical Low Pressure Impactor (ELPI). Measurements were made at ten steady-state operational modes of various loads at two engine speeds. It was found that the geometric mean diameters of particles from SME and Adiesel were lower than that from base diesel fuel. Compared to diesel fuel, SME emitted more ultra-fine particles at rated speed while emitting less ultra-fine particles at maximum speed. Ultra-fine particle number concentrations of A-diesel were much higher than those of base diesel fuel at most test modes.     

Indoor-outdoor air pollution relations: particulate matter less than 10 μm in aerodynamic diameter (PM10) in homes of asthmatics

Concentrations of particulate matter are typically measured at fixed-site sampling locations selected to provide representative measurements of pollutant levelsin a given geographic area. These fixed-site monitors, however, may not adequately measure exposure of humans to particles; and among the major air pollutants, particles less than 10 μm in aerodynamic diameter (PM10) have received relatively little attention in indoor-outdoor and personal exposure studies. These particles reach the deepest airways and are also known to contain a number of compounds including sulfates, nitrates and carcinogens. In order to investigate the relationship between indoor and outdoor PM10 mass concentrations, a pilot investigation was conducted in 10 homes, 9 with resident asthmatics, in southern California. Sampling was conducted using PM10 and cyclone samplers inside and outside of each home with particle collection of Teflon filters. Mass was determined gravimetrically and mass concentrations were determined by pre- and post-sampling flow checks using a calibrated rotameter. PM10 and cyclone masses were reproducibly measured, as determined with paired field samples and laboratory pretesting. PM10 and cyclone masses were well correlated (R²=0.89, n=27) with slightly more mass found on the PM10 samplers, as expected. In the homes of non-smokers and asthmatics surveyed in this study, indoor concentrations were consistently lower than outdoor concentrations (ratio of PM10 indoor/outdoor medians=0.70; ratio of cyclone indoor/outdoor medians=0.79). Indoor cyclone concentrations were moderately correlated with outdoor concentrations (R²=0.56), indicating that much of the variation of indoor concentrationswas driven by variation in ambient concentration. The indoor concentrations of PM10 were less well correlated to outdoor PM10 (R²=0.34), presumably due to larger size particles or different chemical characteristics of PM10 compared to cyclone-collected particles. When data from the non-asthmatic's homes were removed, the correlations between indoor and outdoor concentrations were increased. The homes of these non-smokers and asthmatics afforded some protection from higher outdoor concentrations of particles less than 10 μm in aerodynamic diameter.     

北京夏季高温高湿和降水过程对大气颗粒物谱分布的影响

2004-07-13～2004-08-23使用TDMPS-APS系统在线测量颗粒物的数浓度谱分布,并于07-16～07-18选取了高温闷热夜晚、日间高温高湿和雨后晴朗干洁3种天气条件,使用多级串联撞击式采样器(MOUDI)测量颗粒物的质量浓度谱分布,结果表明,高温高湿天气条件下颗粒物的污染、尤其细粒子污染严重,导致很低的能见度(2.5km);PM_1.8和PM₁₀的质量浓度分别为170.68μg/m³和249.35μg/m³,细粒子质量浓度占PM10的68%;粒径为50～100nm颗粒物的数浓度最高,为2×10⁴～3×10⁴个/cm³;降雨过程对粗粒子和细粒子均有去除作用,对细粒子的去除作用尤为明显;降雨后PM₁₀和PM_1.8浓度分别比降雨前降低3倍和6倍;降雨过后的晴朗干洁天气有利于新粒子(3～20nm)的生成,生成的新粒子快速长大到50～100nm;随着污染物的累积,以后几天内又变为污染天气.     

催化型连续再生颗粒捕集器对生物柴油发动机排放颗粒理化特性的影响

以某重型柴油机为原机,研究氧化催化转化器(Diesel Oxidation Catalyst,简称"DOC")与催化型颗粒捕集器(Catalyzed Diesel Particulate Filter,简称"CDPF")结合而成的催化型连续再生颗粒捕集器(Catalyzed Continuously Regeneration Trap,简称"CCRT")对燃用B20混合燃料柴油机颗粒排放理化特性的影响.试验结果表明:生物柴油发动机安装CCRT装置后排放的颗粒质量和数量均显著低于原机.CCRT装置对不同粒径颗粒的捕集效率不同,对聚集态颗粒的捕集效果略优于核态颗粒.与原机相比,安装CCRT后PAHs总排放量下降,在检测到的20种PAHs中有17种排放量减少.按环数比较,原机及安装CCRT装置后PAHs均以三环和四环为主.CCRT装置的安装使生物柴油发动机排放颗粒中化学成分毒性降低.     

The polynuclear aromatic hydrocarbon (PAH) content of herbage from a long-term grassland experiment

Herbage samples harvested and stored from a long-term agricultural experiment started in the 1850s at Rothamsted Experimental Station (U.K.) have been analysed for polynuclear aromatic hydrocarbons (PAHs). The changing PAH content of samples since 1900 is thought to reflect broadly changes in the PAH content of air. Herbage concentrations ranged between 580 and 2750 μg ΣPAH kg⁻¹ (total of 15 compounds). The lowest concentrations since 1900 were measured in the most recent samples (since the 1960s), with the highest between 1930 and 1955. Samples taken before 1956 contain statistically lower PAH contents than samples taken after this date, suggesting a reduction in PAH emissions from local and/or national sources. Samples taken between 1860 and 1900 contained much higher concentrations of ΣPAH (between 3620 and 6550 μg ΣPAH kg⁻¹) and a different mixture of compounds. These samples may have been contaminated in the drying process after harvesting and prior to storage. The ΣPAH contents of these samples therefore probably do not reflect the atmospheric burden of PAHs at that time.     

Measurement and evaluation of acid air pollutants in Chicago using an annular denuder system

The cyclone/annular denuder/filter pack sampling system (ADS) was used to collect and evaluate ambient air pollutants in Chicago. Eighty-one 12-h samples, equally divided into day/night intervals, were collected from April 1990 to March 1991. The chemical species measured were HNO₃, HNO₂, SO₂ and NH₃ in the gas phase, and SO₄²⁻, NO₃⁻, NH₄⁺, and H⁺ in the particulate phase.The ADS data were collected simultaneously with PM10 samples. The particulate matter was analysed for elemental composition. These compositions were combined with the ADS observations and subjected to evaluation using a chemical mass balance receptor model (CMB). From the CMB analysis, the sum of the contributions from soil (15%), mobile (14%), incinerator (2%), coal (0.6%), steel (0.3%) and refinery (0.2%) was 32% of the PM10. NO₃⁻, which was not included in the fingerprints, represented an additional 9% of the PM10. Residual SO₄²⁻ and residual organic carbon, possibly formed in the atmosphere, represented an additional 22 and 20% of the PM10, respectively, leaving only 17% from other unidentified sources. From the standpoint of source contributions of sulfur and nitrogen compounds, coal combustion (23%) and refinery emissions (23%) are the major contributors of ambient sulfur (with 49% from unidentified sources). Mobile sources (87%) contributed most of the ambient nitrogen (with only 2% from unidentified sources).     

生物柴油发动机颗粒排放物粒径及其分布试验研究

为获取燃用不同比例生物柴油的发动机排放颗粒物粒径及其分布特性,对1台增压直喷式车用柴油机进行了台架测试.用80 L/min定量泵和装有直径90 mm的玻纤滤膜采样器在排气管内采样10 min,用激光粒度仪测量与分析颗粒粒径和分布.结果表明,随着发动机转速提高,排放颗粒粒径变小且分布更集中.干法众数对应的粒径级较大（约10～12 μm）且较集中,湿法众数的较小（约4～10 μm）且分散.用干法分析,发动机低速时,B100的Sauter平均直径d₃₂最大,纯柴油最小,而B20的结果介于二者之间.而高速时B20的粒径最大,纯柴油次之,B100最小.中数粒径d(0.5)的结果也反映这一趋势.用湿法分析,除了2?000 r/min点外, B20的d₃₂最大,B100次之,柴油最小.湿法众数比干法分散,因而d₃₂也较大.     

DOC+CDPF对生物柴油燃烧颗粒排放特性的影响

以一台满足国五排放法规的车用柴油机为样机,研究加装氧化催化转化器DOC与催化型颗粒捕集器CDPF(DOC+CDPF后处理装置)前后,柴油机燃用B20燃料(燃料含20%体积掺混比的生物柴油)的颗粒排放特性.结果表明,在未加装该后处理装置时,该机排气颗粒数量浓度的粒径分布呈双峰形态,B20燃料的排气颗粒数量浓度的峰值粒径在10nm和50nm附近,纯柴油的排气颗粒数量浓度的峰值粒径在50nm和200nm附近.在颗粒粒径小于120nm的区域,该机燃用B20燃料的排气颗粒数量浓度大于纯柴油.加装该后处理装置后,该机排气颗粒数量浓度的粒径分布呈多峰形态,峰值粒径在10nm、20nm和60nm附近.加装DOC+CDPF后,不论是柴油还是B20燃料,与原机相比,柴油机排气颗粒总数量下降明显,其中60~200nm粒径范围的颗粒数量浓度降幅更为显著.在相同工况下,DOC+CDPF对柴油机燃用B20燃料的颗粒总数量净化效率高于纯柴油.     

邯郸市PM_(10)、PM_(2.5)和PM_(1.0)在线监测研究

对2015年3月—2016年2月邯郸市大气中的PM_(10)、PM_(2.5)和PM_(1.0)进行了在线监测,探讨了其质量浓度的变化特征,并分析了其质量浓度与风速、风向的关系。结果表明:邯郸市颗粒物质量浓度水平较高,β射线吸收法所监测的PM_(10_WET)、PM_(2.5_WET)和PM_(1.0_WET)年均浓度值分别为202.5,114.8,81.1μg/m~3,PM_(2.5_DRY)/PM_(10_WET)和PM_(2.5_WET)/PM_(10_WET)分别为0.58、0.70,PM_(1_DRY)/PM_(2.5_WET)和PM_(1_WET)/PM_(2.5_WET)分别为0.58、0.71,PM_(2.5)为PM_(10)中的主要组成,PM_(1.0)为PM_(2.5)中的主要组成。邯郸市PM_(10)、PM_(2.5)和PM_(1.0)质量浓度冬季最高;PM_(10)、PM_(2.5)和PM_(1.0)日变化峰值为上午09:00左右,谷值为下午16:00左右,扬沙、降雨,霾和春节不同条件下PM_(10)、PM_(2.5)和PM_(1.0)差异明显。邯郸市PM_(10)、PM_(2.5)和PM_(1.0)的浓度高值主要分布在风向0°~100°和175°~225°、风速小于1 m/s的情况下。     

城市交通干道降雨径流中PAHs的污染特征

以上海、温州市典型交通干道地表径流为研究对象,分析了样品中16种溶解态和颗粒态PAHs浓度,了解了城市交通干道降雨径流中PAHs污染特征及其动态变化过程.结果表明,径流中∑PAHs(包括溶解相、颗粒相)浓度范围为919.8～16711.6ng·L-1,溶解相中PAHs浓度要远低于颗粒相(分别为4.9～1558.0ng·L-1,635.4～16624.0ng·L-1).通过对3场降雨事件中PAHs浓度随降雨过程变化的研究,可以发现并不是所有道路径流都有初期冲刷效应,初期冲刷的产生受雨前干期、降雨强度以及径流量等因素共同作用,因此简单拦截初期径流并不能十分有效地降低PAHs污染负荷.径流中PAHs在颗粒相-水相间的分配系数Kp值为2.3×104～2.5×106L·kg-1,随着悬浮颗粒物含量增加而减少,这可能跟径流过程中颗粒物粒径组成有关.