Y型内混双级雾化喷嘴流量特性研究

对自行设计的 Y 型内混双级雾化喷嘴进行了实验研究,分析了不同喷嘴尺寸对喷嘴流量特性的影响.对比了压缩空气与过热蒸气做雾化介质的不同.通过测量喷嘴内混室压力,拟合出了供气压力-内混室压力曲线,并通过实验测量和校核,得到工质流景系数的表达式,对喷嘴设计有指导作用.     

Source identification of PCDD/Fs in agricultural soils near to a Chinese MSWI plant through isomer-specific data analysis

Isomer-specific data were investigated in order to identify the sources of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in agricultural soils, including Fluvo-aquic and paddy soils, in the vicinity of a Chinese municipal solid waste incineration (MSWI) plant. Homologue and isomer profiles of PCDD/Fs in soils were compared with those of potential sources, including combustion sources, i.e., MSWI flue gas and fly ash; and the impurities in agrochemicals, such as the pentachlorophenol (PCP), sodium pentachlorophenate (PCP-Na) and 1,3,5-trichloro-2-(4-nitrophenoxy) benzene (CNP). The results showed that the PCDD/F isomer profiles of combustion sources and agricultural soils were very similar, especially for PCDFs, although their homologue profiles varied, indicating that all the isomers within each homologue behave identically in the air and soil. Moreover, factor analysis of the isomer compositions among 33 soil samples revealed that the contamination of PCDD/Fs in agricultural soils near the MSWI plant were primarily influenced by the combustion sources, followed by the PCP/PCP-Na and CNP sources. This implication is consistent with our previous findings based on chemometric analysis of homologue profiles of soil and flue gas samples, and identifies PCP/PCP-Na as an additional important source of PCDD/Fs in the local area. This makes the similarities and differences of isomer profiles between Fluvo-aquic and paddy soils more explainable. It is, therefore, advisable to use isomer-specific data for PCDD/F source identifications where possible.     

Dioxins and their fingerprint in size-classified fly ash fractions from municipal solid waste incinerators in China—Mechanical grate and fluidized bed units

The distribution of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs), in brief dioxins, has seldom been addressed systematically in fly ash from municipal solid waste incinerators (MSWIs). This study shows the amount and fingerprint of PCDD/Fs in fly ash from four different Chinese MSWIs, that is, three mechanical grate units and one circulating fluidized bed unit. In these fly ash samples, dioxins-related parameters (international toxic equivalent quantity, total amount of PCDD/Fs, individual isomer classes, and 17 toxic 2,3,7,8-substituted congeners) all tend to increase with decreasing particle size for mechanical grate incinerators, yet only for the finest fraction for fluidized bed units. Moreover, the fluidized bed incinerator seems superior to grate incineration in controlling dioxins, yet a comparison is hampered by internal differences in the sample, for example, the fluidized bed fly ash has much lower carbon and chlorine contents. In addition, the presence of sulfur from mixing coal as supplemental fuel to the MSW may poison the catalytic steps in dioxins formation and thus suppress the formation of dioxins. With more residual carbon and chlorine in the fly ash, it is easier to form dioxins during cooling. Nevertheless, there is no apparent relation between Fe, Cu, and Zn contents and that of dioxins in fly ash.

Implications This paper is of interest because it presents the amounts and distribution of PCDD/Fs in fly ash samples from some typical waste incineration plants in China, featuring distinct incinerator types, combustion conditions, fuel composition, or residual carbon, chloride, and heavy metal contents in fly ash.     

金属尾矿作水泥混合材活性试验研究

选取烧失量低于10%,SO3含量低于3%,SiO2、Al2O3含量较高,适于作水泥混合材的6种金属尾矿进行水泥混合材活性试验研究.6种金属尾矿分别按10%、15%、20%、25%、30%与熟料、石膏进行配比.试验结果表明:6种金属尾矿不同掺配比活性试验的R28在68.72%～76.54%之间,高于活性混合材R28为62%的判定指标,由此可认为此6种尾矿均属于活性混合材,可单独用作水泥活性混合材;6种金属尾矿掺配比在小于30%的范围内,水泥安定性、凝结时间等性能指标均符合普通硅酸盐水泥要求;6种金属尾矿掺配比在小于30%的范围内其强度均满足32.5R等级水泥强度要求;尾矿掺配比为10%时,6种金属尾矿除3号尾矿外,均满足42.5R等级水泥强度要求.符合要求的金属尾矿用作水泥混合材,将扩大水泥混合材来源,降低水泥粉磨能耗和成本,实现尾矿的资源化和水泥工业的可持续发展.     

汽车内空气甲醛污染状况及其影响因素分析

为了解车内空气甲醛污染状况及其影响因素,随机测定200辆私家轿车车内空气甲醛浓度、温度和湿度,同时通过问卷调查获得车型、车龄、车内装饰物和关窗时间等基本情况.检测可知,车内空气甲醛几何均数为0.030 mg/m 3 ,95%可信区间为0.027～0.033 mg/m 3 .参照《室内空气质量标准》(GB/T 18883-2002)规定为0.100 mg/m 3 ,超标率为1.5%.车内空气甲醛对数质量浓度(y)与车龄(X 1 )、车内温度(X 2 )、汽车档次(X 3 )、车内温度×关窗时间(X 4 )有关,回归方程为y=-2.088 5-0.096 6X 1 0.019 9X2 0.049 5X 3 0.002 2X 4 .表明车内甲醛污染主要存在于车龄不足半年、关窗时间超过3 h以上的车辆,降低车内温度可有效控制车内甲醛污染.     

亚热带典型农林混合流域河流氮磷输出负荷特征及与景观格局关系

流域景观特征对流域河流氮(N)磷(P)迁移输出具有显著影响,但不同景观组成与配置与河流N、P输出负荷的关系有待进一步深入研究。以亚热带典型农林混合流域金井河流域为研究区域,基于长期水文、水质定位观测数据定量估算了河流N、P输出负荷。将景观指数分类结合传统统计分析筛选出的不同景观尺度的核心景观指数,采用冗余分析(RDA)和方差分解分析(VPA)明确不同尺度景观格局特征对于河流N、P输出负荷的影响关系。结果表明：流域丰水期、平枯水期N、P输出负荷呈显著时空差异,丰水期流域河流TN、NH₄⁺-N、NO₃^--N、TP、DIP输出负荷分别为2.61～9.03、0.34～5.34、1.26～5.03、0.15～0.50、0.09～0.23 kg/(hm².a);平枯水期分别为1.55～6.68、0.29～2.91、0.74～2.91、0.10～0.46、0.05～0.20 kg/(hm².a)。不同景观尺度水平及土地利用类型,景观特征对于N、P输出负荷的影响有所差异,...     

发达国家和地区生态环境监测发展经历对中国的启示

新形势下,中国生态环境监测面临新任务和新挑战,迫切需要明确发展思路和方向.因此,从环境监测管理体系、业务体系、标准方法体系等方面,举例浅析了美国、欧盟等发达国家和地区环境监测业务的发展现状,并从法律制度、业务体系、方法标准等方面对比分析了中国与发达国家和地区的差异及不足,总结归纳了适用于中国国情的先进经验与启示.在此基...