PM2.5在线源解析技术应用

采用在线单颗粒气溶胶质谱仪对某区域大气细颗粒物PM_(2.5)进行连续在线源解析监测,综合分析了PM_(2.5)的组成成分及来源。该区域8月份PM_(2.5)污染来源综合性较强,主要为机动车尾气源19.7%、扬尘源17.2%、二次无机源15.4%、生物质燃烧源12.9%、燃煤11.3%,此外工业工艺源4.4%、其他11.2%。在线源解析技术为环保管理部门科学制定PM_(2.5)污染防治措施,实现精准管控提供了技术依据。     

高湿轻质废渣的烘干处理及工艺设备特点

<正>1常见高湿轻质废渣种类及特性1.1粉煤灰与煤渣粉煤灰是煤燃烧所产生的烟气中的细灰(一般是指燃煤电厂从烟道气体中收集的细灰)。粉煤灰大部分是球状,表面光滑的细小颗粒,比重:1.8～2.4,容重:500～880kg/m3,4900孔筛余量:30%～50%,标稠水量:24%~70%,比表面     

基于SPAMS研究汕头市潮阳区春冬季污染天气过程的细颗粒物组分变化特征

为了更好地了解空气污染过程中细颗粒物组分的变化特征,采用单颗粒气溶胶质谱(SPAMS)法,于2015年2月在汕头市潮阳区城南街道办事处六楼对空气污染过程进行连续观测。根据细颗粒物的质谱特征,将其化学组分分为9类,为元素碳(EC)、混合碳(ECOC)、富钾颗粒(K)、富钠钾颗粒(NAK)、重金属(HM)、矿物质(SIO3)、有机碳(OC)、高分子有机碳(HOC)以及左旋葡聚糖颗粒(LEV)。将本次污染过程分为6个时段进行分析,结果表明各个阶段中占比最大的化学组分均为OC、EC、ECOC,这三种化学组分的总占比达到58. 7%～73. 6%。在空气污染上升和持续阶段,OC和ECOC占比增长明显(尤其是OC),OC是这两个阶段中占比最大的化学组分,占比分别达到27. 8%和32. 5%,这两类细颗粒物是本次空气污染过程中的特征组分。本次污染过程中,机动车尾气源在空气优良时段贡献率最大,而在空气污染上升和持续阶段燃煤源贡献率最为显著,占比分别达到32. 9%和41. 5%,这是本次空气污染过程的一个突出特点,燃煤源是本次空气污染过程的主要来源。综合污染过程成分分析、来源分析及气象条件可得出,潮阳区本次持续污染过程主要是由于气象扩散条件不利,风速小,湿度大,燃煤源颗粒富集过多导致污染升级。建议在重污染天气时可优先考虑加强对燃煤源采取管控措施。     

喷淋塔内可吸入颗粒物的脱除与凝结增长特性

引言 可吸入颗粒物是一种重要的大气污染物,其对人类健康和大气环境带来极大危害[1-2].在当前以燃用化石燃料为主的能源结构和与日俱增的能源消耗形势下,燃烧源的排放成为可吸入颗粒物的一个重要来源[3],主要原因是目前电站及工业生产中的除尘设备,如电除尘器、过滤除尘器等虽然已达到很高的水平,但对可吸入颗粒物的脱除效率却较低,使得大量颗粒排放到大气中.     

燃烧源超细颗粒物的研究进展

燃烧源超细颗粒物已成为大气环境污染的突出问题，并日益引起世界各国的高度重视，对燃烧源超细颗粒物的国内外研究现状进行了评述，介绍了超细颗粒物在大气中的分布和来源、超细颗粒物的危害以及燃煤电厂超细颗粒物排放和控制方法，并总结了超细颗粒物研究的难点所在，指出了进一步研究的重点和方向。     

大气颗粒物中金属元素检测和来源解析研究进展

大气颗粒物中金属元素能够通过呼吸系统进入人体,造成人体机能障碍,引发各种疾病。综述了大气颗粒物中金属元素的主要检测技术和来源解析方法。今后研究中,应加强不同类型检测仪器测定结果的比对;操作简便、多元素同时测定、检测线性范围宽、时间分辨率高是未来检测仪器的发展趋势;应综合利用多种源解析技术,确定大气颗粒物中金属元素的来源。     

燃煤锅炉烟气脱硫技术对颗粒物排放影响研究进展

随着环境问题的日益严峻及燃煤锅炉超低排放工作的实施,由燃煤引起的大气污染问题及脱硫和除尘设备协同脱除污染物的作用逐渐受到关注。由燃煤释放的SO2和颗粒物对人类健康及自然环境造成严重危害,因此对SO2和颗粒物的治理至关重要。笔者综述了湿法烟气脱硫技术如石灰石-石膏法、氨法等,半干法烟气脱硫技术如循环流化床烟气脱硫技术(CFB)、高倍率灰钙循环烟气脱硫(NGD)等以及干法烟气脱硫技术如电子射线辐射法脱硫技术、活性炭(活性焦、活性半焦)吸附脱硫技术等的发展历史、技术特点及适用范围,并对比分析了各脱硫技术对颗粒物排放特性的影响。结果表明,湿法烟气脱硫技术SO2脱除效率最高,尤其是石灰石-石膏法烟气脱硫技术,总效率可达99%以上。入口颗粒物浓度高于5 mg/m^3时,此技术能够协同脱除烟气中的颗粒物,除尘效率可达50%~80%,脱硫前后粒径分布都为典型的双峰分布,且脱硫后粒径峰值向小粒径偏移,硫酸盐成分增加;入口颗粒物质量浓度低于5 mg/m^3时,出口颗粒物浓度可能出现不降反增的现象,另外,由于其投资和运行成本高,多应用于大型燃煤机组和脱硫剂来源丰富的地区,同时湿法烟气脱硫产物还具有一定的经济效益;半干法和干法烟气脱硫技术SO2脱除效率在60%~90%,与湿法脱硫技术相比具有投资和运行成本低,占地面积小和节约水资源等优点,在中小型锅炉领域如燃煤工业锅炉具有较好的应用前景,但大量脱硫产物和脱硫剂随烟气进入除尘设备,浓度高达1 000 g/m^3以上,为除尘设备造成极大的运行压力,加大了投资和运行成本。目前半干法烟气脱硫技术及干法烟气脱硫技术对颗粒物排放特性的影响研究较少,还需在脱硫系统对颗粒物粒径、成分及形貌特性等方面的影响规律做进一步研究。     

煤燃烧过程颗粒物及其前驱体形成机制研究

煤粉燃烧产生的颗粒物是大气中PM的最为主要的来源。通过煤粉燃烧过程中煤粉成分、粒度组成和燃烧条件对PM2.5产生浓度、成分等特性进行必要的研究,找到了该煤种燃烧的前驱体,为后续除尘,降低PM排放打下了基础。     

煤焦燃烧过程中细模态颗粒物的生成机理及研究进展

实现燃煤颗粒物(PM)污染排放控制必须深入了解颗粒物排放规律及生成机理。煤粉燃烧过程中产生飞灰颗粒粒径分布为粗模态,细模态和超细模态3种。与粗模态PM相比,细模态PM占比较大,其小粒径与富集性特点影响人体健康及大气环境。同时,相对于形成过程与机理相对成熟的超细模态PM,细模态PM形成机理及研究进展尚缺乏系统总结,抑制细模态PM排放存在困难。笔者分析了细模态PM的形成机理(焦炭颗粒的破碎、矿物质熔融聚合、外在矿物质破碎、表面灰粒的脱落)及主要影响因素,探讨了模拟研究进展并指出未来研究重点。煤灰PM粒径分布主要是焦炭颗粒破碎与矿物质聚合行为这2个因素相互竞争的结果。破碎行为使得细模态PM数量增多粒径减小,而矿物质聚合使得PM数量减小,有利于粗模态PM形成。影响PM形成的主要因素有孔隙结构、燃烧模式与焦炭粒径。孔隙率较高的煤胞型焦炭相较于其他结构焦炭更易发生破碎,产生更多细模态PM。增加温度与氧含量,降低粒径均有助于PM生成,但较高温度下灰粒的聚合可能导致粒径分布倾向于粗模态PM。破碎行为对焦炭燃烧特性模拟大致分为群体平衡模型和逾渗模型2类。基于细模态PM形成机理与影响因素,认为逾渗模型考虑了焦炭本身孔隙结构,更适于模拟焦炭破碎行为。本征动力学燃烧模型与逾渗模型的结合是准确预测灰颗粒粒径分布的关键,是下一步的研究重点。     

我国机动车和燃油锅炉颗粒有机物排放特征

颗粒有机物是大气污染物的重要成分,对人体健康、雾霾形成具有重要影响。化石燃料燃烧是其最主要的来源之一。本研究选取我国不同燃油类型的机动车和燃油锅炉,利用稀释通道法采集了机动车及锅炉运行中排放的细颗粒物,并利用柱前衍生化GC-MS方法分析了其有机成分。在定量分析的约195种有机化合物中,机动车排放的理想示踪物霍烷和甾烷类物质均可被检出;芘/苯并[a]芘的值、苯并[ghi]苝和晕苯可以用来区分汽油车和柴油车排放;燃油锅炉排放的正构烷烃、正构烷酸、正构烷醇和多环芳烃与柴油车排放有相似之处,在颗粒物源解析研究中应单独考虑,否则可能会高估机动车的贡献;芳香酸可以用来区分燃油锅炉和其他污染源。与国外有机污染物排放源谱相比,我国机动车排放因子偏高,不同类别机动车排放因子具有较大差异。相同工况条件下,燃油类型对燃油锅炉排放因子有着较大影响。基于上述分析建立了我国不同类型机动车和燃油锅炉排放颗粒有机物的源成分谱。     

Particle size distribution of PM-10 and heavy metal emission with different temperature and HCl concentrations from incinerators

Emission characteristics of particulate matter and heavy metals from 12 small waste incinerators, whose capacity ranged from 25 to 200 kg/h of waste, were investigated to determine the factors affecting the particulate matter generation and growth mechanisms. The ratio of fine particles to coarse particles increased with the flue gas temperature. Particulate matter showed bimodal forms in particle size distributions. The finer particle mode in particle size distribution shifted toward the coarser particle mode with a decrease in flue gas temperature. Experimental results were in agreement with coagulation theory: It is thought that the coarser particles were mechanically generated and the finer particles were generated by gas-to-particle conversion mechanisms such as nucleation, condensation, and coagulation. Heavy metal enrichment in finer particulate matter was also observed and related to particle formation and growth from vaporized metals. Emission of all heavy metals except zinc was affected by hydrogen chloride concentrations, while some metal emissions such as manganese, chromium, and copper were not varied with flue gas temperature. This paper is dedicated to Professor Dong Sup Doh on the occasion of his retirement from Korea University.     

Studies of Cd, Pb and Cr distribution characteristics in bottom ash following agglomeration/defluidization in a fluidized bed boiler incinerating artificial waste

This study focused on the effects of agglomeration/defluidization on the Cd, Pb and Cr distribution in bottom ash particles of different sizes. In this study we have incinerated artificial waste, which was a mixture of sawdust, polypropylene, selected metal solutions, and polyethylene. The experimental parameters included Na concentration, addition of Ca and Mg and operating temperature. The results indicated that particle size decreased by attrition and thermal impact in the absence of added Na. When Na was added to the system, this metal reacted with silica sand to form eutectics, which increased particle size. Further addition of Ca and Mg was found to prolong the operating time, with greater amounts of liquid eutectic accumulating, leading to increase particle size.The heavy metal concentrations in coarse and fine particles were greater than those present in particles of intermediate sizes over a range of experimental conditions. As the particle size decreased below 0.59 mm or increased above 0.84 mm, the heavy metal concentrations increased. As Ca and Mg were added, the heavy metal concentrations in particles of all sizes increased relative to those present in identical particles when no metals or only Na were added. Additionally, the ratio of Cd sorption to silica sand decreased with increasing Na concentration, but Cr sorption had the opposite tendency. Therefore, while the addition of Na tended to increase agglomeration, it also increased the tendency for heavy metals to remain in the sand bed of fluidized bed incinerators. Addition of Ca and Mg not only inhibited the agglomeration/defluidization process, resulting in increased operating time, but also enhanced the removal of heavy metals by silica sand, decreasing the concentration of heavy metals in reactor exhaust.     

不同粒径污泥热解制备生物炭及其特性分析

以3种不同粒径污泥为原料,采用固定床反应器在500℃下制备生物炭。考察了3种不同粒径污泥的热解特性及其生物炭中重金属的分布特征,并运用TCLP对污泥及其生物炭的重金属浸出毒性进行了系统研究。结果表明,随着污泥粒径的增大,热解生成的生物炭和热解气产率均有所降低,而焦油产率则逐渐升高;在3种不同粒径污泥热解过程中,重金属除As外主要富集在固体产物生物炭中,相对富集系数均高于90%。随着污泥粒径的增大,污泥中Cu、Zn和Ni的含量增加,而Cr和Pb的含量则减少;虽然3种不同粒径污泥制备的生物炭中重金属的浸出规律不一致,但是污泥热解可以有效抑制重金属的浸出。生物炭中除As和Zn外其他重金属元素的浸出率均低于3.0%。     

Comparison of the characteristics of bottom ash and fly ash from a medium-size (32 MW) municipal district heating plant incinerating forest residues and peat in a fluidized-bed boiler

In this study, the physical and chemical properties of bottom ash and fly ash originating from the co-combustion of biomass-derived fuels (i.e. wood chips, sawdust, bark, and peat) from a 32 MW fluidized bed boiler at a municipal district heating plant were investigated. Silicate minerals were predominant in the bottom ash and calcium minerals in the fly ash, with most of the inorganic nutrients and heavy metals being enriched in the fly ash. The enrichment factors for heavy metals in the fly ash varied between 0.2 for silicon and 16.3 for lead, and for plant nutrients, between 1.5 for phosphorous and 108 for potassium. However, all heavy metal concentrations in both the bottom ash and fly ash were significantly lower than the current Finnish limit for maximum allowable heavy metal concentrations for forest fertilizers, which came into force in March 2007. According to the particle size distribution, the mass loadings of heavy metals in the fly ash were more than 90% contributed by the smallest particle size fraction lower than 0.074 mm. In the bottom ash, between 83.6 and 91.9% of the mass loadings of heavy metals were contributed by the particle size fraction between 0.5 and 2.0 mm.     

Heavy metal characterization of CFB-derived coal fly ash

The present study investigates the heavy metal content of coal fly ash (FA) samples coming from three different sampling points (secondary cyclone, cooler and filter) of a pilot plant combustion facility. The combustion experiments were carried out in a 0.1 MW Circulated Fluidized Bed (CFB) boiler using South African coal, with the addition of limestone for sulfur capture. FA was tested for the presence of selected heavy metals using inductively coupled plasma optical emission spectrometry (ICP-OES); batch leaching tests were conducted as well. The samples were also characterized in terms of their microstructure, chemical and mineralogical composition, total surface area and particle size distribution. Most of the studied metals (Cd, Cr, Cu, Ni, Mn, Zn) showed enrichment in the fine, filter FA particles, while Pb was mostly concentrated in the cooler sample. Regarding leaching characteristics of the examined samples, Cr was found to occur in considerable amounts. Although the use of CFB technology for the combustion of solid fuels steadily gets bigger worldwide, only a very limited number of studies have environmentally assessed CFB-coal FAs to date. Thus, the current study aims to contribute toward building a more integrated knowledge on the environmental impact of this abundant power production by-product.     

粒径对餐厨沼渣热解制备生物炭中磷和重金属的影响

以3种粒径餐厨沼渣为原料,在600℃下热解制备生物炭,研究粒径对沼渣（BR）及生物炭（BRC）中磷和重金属的影响,并采用TCLP浸出毒性和重金属潜在生态风险评估对其安全性进行系统研究。结果表明：BR及BRC中的磷主要以酸溶态磷（HCl-P）为主,残渣态磷（Res-P）次之,其余磷形态含量较低,总磷含量均呈现出随粒径增大而降低的趋势。热解促进H₂O-P、NaHCO₃-P和NaOH-P向HCl-P和Res-P转化。随着粒径的增大,BR中Cu、Zn总量增加,Cr减少,BRC中的Cr、As总量增加,Zn、Pb减少。并且BR中Cr、Zn、Pb和As中可氧化态和残渣态F3+F4随粒径增大而减少;BRC中Cr、Pb、As中F3+F4随粒径增大而减少,而Cu、Zn、Cd与之相反。TCLP浸出毒性和重金属潜在生态风险评估结果表明BR及BRC中重金属均属于低风险水平。     

Spherical AlN particles synthesized by the carbothermal method: Effects of reaction parameters and growth mechanism

In this work, AlN particles with spherical morphology, smooth appearance and controllable particle size were purposely synthesized through an efficient carbothermal strategy at 1800 °C aiding with the CaF₂ additive. The influences of typical synthesis parameters, such as carbon content, CaF₂ particle size and reaction time on the formation rate, particles size and surface morphology of AlN particles were deeply and comprehensively studied. It was indicated that the intermediate Ca-aluminates was extremely essential to enhance the nitridation rate, promote the AlN growth and form the spherical morphology. More importantly, based on the systematic investigations and intensive analyses, the underlying growth mechanism of spherical AlN particles in the carbothermal process was rationally proposed and elaborated herein.     

催化裂化油浆固含量测定及组成分析

采用灰分法、过滤法、离心法测量了某重油催化裂化装置外甩油浆的固体颗粒含量,对几种方法在固含量测定方面的结果差异进行对比分析。实验结果表明,离心法测量的固含量约为2850μg/g,介于灰分法和过滤法之间。离心法结果显示,油浆中重组分与细粉颗粒存在较强的吸附作用,分离中能否准确得到焦粉是造成结果差异的主要原因。离心法耦合后续焙烧能够分离获得油浆中一定量的催化剂细粉颗粒,通过激光粒度仪、元素分析仪、XRD、BET、SEM-EDS等手段对分离得到的固体颗粒以及初始FCC催化剂进行了表征。FCC催化剂粒径集中在32～120μm之间,为规则的球形分布,油浆中的固体颗粒呈不规则的块状分布,粒径在0.4～40μm之间,其中催化剂细粉的粒径在1～30μm之间;催化裂化油浆中的固体颗粒组成主要有催化剂细粉、焦粉和碱金属K、Ca、无机盐和金属元素Sb、Fe等。     

不同粒径城市垃圾焚烧飞灰中重金属的浸出规律研究

集中焚烧法已经逐渐成为我国城市生活垃圾处理的主要方式,但其中的重金属在焚烧过程中不会被破坏,最终主要集中在垃圾焚烧飞灰中排出。在垃圾焚烧飞灰的安全填埋过程中由于受到环境因素的影响,例如酸雨,其中的重金属会逐渐的发生迁移,从而影响环境。文章对不同粒径的垃圾焚烧飞灰中的重金属浸出特性进行了研究,实验结果表明：小粒径垃圾焚烧飞灰所占比例较大。不同粒径对重金属的浸出特性比较复杂,浸出浓度均不相同,其中除尘器飞灰中的重金属浸出浓度远高于其他三种飞灰,属于有浸出毒性的危险废物。     

The effects of agglomeration/defluidization on emission of heavy metals for various fluidized parameters in fluidized-bed incineration

The agglomeration/defluidization may be produced to generate the secondary pollutant during incineration. However, the effects of agglomeration/defluidization on heavy metal distribution have rarely been examined. Therefore, the effects of the agglomeration/defluidization process on heavy metal emission in flue gas are studied. The artificial waste is employed to simulate municipal waste and to form agglomerates, which contain alkali metals, earth alkali metals, a mixture of metals (Pb, Cr and Cd) and sawdust. The fluidized parameters (including gas velocity, sand particle size and static bed height) are varied to determine their influences on heavy metal emission. The results indicate that addition of Na increases the risk of agglomeration/defluidization, but the emission concentration of heavy metals decreases during agglomeration/defluidization. The heavy metals may react with Na to form the eutectics or are covered and adhered by the liquid-phase eutectics of Na to stay in sand particle and lead to a decrease in the emission of heavy metals.The system was operated at a low gas velocity that not only easily resulted in agglomeration/defluidization but also increased the emission concentration of heavy metals. Large particles (920 μm), which have a poor fluidized quality, had the highest emission concentration. Small particles (645 μm) were uniformly fluidized to enhance the fluidization quality and to decrease the emission concentration. Additionally, adding Ca did not decrease the heavy metal emission concentration, but maintained the fluidization during eutectic accumulation. The Ca prevented the sand bed from quickly achieving defluidization and prolonged the increased emission of heavy metals after defluidization.