Experimental investigation of wood combustion in a fixed bed with hot air

Waste combustion on a grate with energy recovery is an important pillar of municipal solid waste (MSW) management in the Netherlands. In MSW incinerators fresh waste stacked on a grate enters the combustion chamber, heats up by radiation from the flame above the layer and ignition occurs. Typically, the reaction zone starts at the top of the waste layer and propagates downwards, producing heat for drying and devolatilization of the fresh waste below it until the ignition front reaches the grate. The control of this process is mainly based on empiricism.MSW is a highly inhomogeneous fuel with continuous fluctuating moisture content, heating value and chemical composition. The resulting process fluctuations may cause process control difficulties, fouling and corrosion issues, extra maintenance, and unplanned stops. In the new concept the fuel layer is ignited by means of preheated air (T > 220 °C) from below without any external ignition source. As a result a combustion front will be formed close to the grate and will propagate upwards. That is why this approach is denoted by upward combustion.Experimental research has been carried out in a batch reactor with height of 4.55 m, an inner diameter of 200 mm and a fuel layer height up to 1 m. Due to a high quality two-layer insulation adiabatic conditions can be assumed. The primary air can be preheated up to 350 °C, and the secondary air is distributed via nozzles above the waste layer. During the experiments, temperatures along the height of the reactor, gas composition and total weight decrease are continuously monitored. The influence of the primary air speed, fuel moisture and inert content on the combustion characteristics (ignition rate, combustion rate, ignition front speed and temperature of the reaction zone) is evaluated.The upward combustion concept decouples the drying, devolatilization and burnout phase. In this way the moisture and inert content of the waste have almost no influence on the combustion process. In this paper an experimental comparison between conventional and reversed combustion is presented.     

Relationship between deposition and attachment rates in Jacobi room model

It is shown in this work that parameters of the Jacobi model, which describes behavior of short-lived radon progeny, are not independent. The relationship between deposition rate of attached radon progeny and attachment rate of their unattached fraction was determined in this paper. It was found that deposition rate increases when the attachment rate is smaller; this effect is more pronounced for larger friction velocity. The deposition rate of attached radon progeny is presented here as a function of friction velocity, ventilation and attachment rate. Deposition rate of attached fraction was estimated in the range 0.012-0.46 h⁻¹, when attachment rate varies from 10 h⁻¹ to 100 h⁻¹.     

金华江流域利用硅藻生物学特性监测水质研究

2012年7月对浙江省金华江流域18个监测断面进行了附着硅藻和水质调查，通过硅藻生态群落组成及SPI、BDI硅藻指数对水质进行了评价，并比较了硅藻指数评价与水质理化评价结果的异同性。本次调查共收集到硅藻75种（含变种和变型），隶属于2纲12科30属。硅藻生态类群组成显示各断面以喜中性、N自养、耐低污染和喜好很高氧饱和度硅藻为主。水质理化指标总体评价金华江各监测断面水质多为Ⅲ类及以上，仅有一个断面为V类，硅藻SPI和BDI指数评价各断面水质为中等及中等以上。二者评价结果总体上吻合，但同时存在一定差异。SPI与高锰酸盐指数和硝酸盐氮呈显著负相关，BDI与氨氮呈显著负相关。硅藻指数在金华江流域有一定的适用性，但其在国内其他流域的适用性、评价方法的指示性与稳定性有待进行更深入的研究     

青弋江流域不同级别河流底栖动物群落结构研究

2013年8月对青弋江流域不同级别河流底栖动物进行了调查。共采集到底栖动物60种，隶属于39科58属。从1级到4级河流，种类数表现出逐渐减少的趋势，分别为46、39、36和16种。1~3级河流中种类数最多的均是水生昆虫，4级河流中种类数最多的是软体动物。整个流域底栖动物密度和生物量分别为382 ind./m2和3643 g/m2。不同级别河流中，2级河流底栖动物密度最大，4级河流密度最小，且二者存在显著差异；2级和4级河流底栖动物生物量都较高，且显著高于1级河流。在功能摄食类群方面，整个流域以刮食者和过滤收集者为主。随着河流级别的增加，刮食者相对密度和相对生物量表现出先增加后下降的趋势；撕食者在1、2级河流所占比例较高；直接收集者和过滤收集者在1级和4级河流中所占比例较高     

Wild fire impact on copper, zinc, lead and cadmium distribution in soil and relation with abundance in selected plants of Lamiaceae family from Vidlic Mountain (Serbia)

Fire has been considered as an improving factor in soil quality, but only if it is controlled. Severe wild fire occurred in the summer 2007 on the Vidlic Mountain (Serbia) overspreading a huge area of meadows and forests.Main soil characteristics and content of heavy metals (Cu, Pb, Cd, Zn) in different fractions obtained after sequential extraction of soil from post-fire areas and from fire non disturbed areas were studied. In four plant species of Lamiaceae family (Ajuga genevensis L., Lamium galeobdolon (L.) L., Teucrium chamaedrys L., Acinos alpinus (L.) Moench.), that grow in typical habitats of the mountain, distribution of heavy metals in aerial parts and roots was investigated too.For all samples from post-fire area cation exchange capacity and soil organic matter content are increased while rH is decreased. Fire caused slightly increased bioavailability of the observed metals but more significant rise happened in metal amounts bound to oxides and organics. The plants showed variable behavior. T. chamaedrys collected on the post-fire area contained elevated concentrations of all analyzed metals. A. alpinus showed higher phytoaccumulation for Zn and Cd, while the other two plant species for Pb and Cd in the post-fire areas.     

鄱阳湖生态经济区交通格局演变及区域效应研究

应用ArcGIS空间分析和可达性评价模型，结合SPSS、Matlab等软件，以鄱阳湖生态经济区为研究区域，选取1998年、2008年及2020规划年为时间断面，用栅格法测算交通可达性，分析可达性格局空间演变特征。根据城市质量和时间距离，构建经济联系评价模型，回归分析预测2020年城市质量。对区域内经济总量空间集聚进行分析，并根据三个时间段的最大经济联系格局演变，分析城市间经济辐射范围和城市隶属关系变化。结果发现：区域内可达性改善明显，城市间可达性差距缩小，到2020年全区可基本实现一日交流；区域内经济总量集聚明显，且处于极化状态；由于鄱阳湖湖体的阻隔，区域内形成以南昌、九江、景德镇三大经济中心地，其他为隶属城市的经济联系格局；建议发展南昌至贵溪尤其是东乡至鹰潭段的交通，使鹰潭成为区内第四个经济中心地，实现全区均衡发展     

Characterization and optimization of an online system for the simultaneous measurement of atmospheric water-soluble constituents in the gas and particle phases

In this work we present the results of extensive characterization and optimization of the Ambient Ion Monitor-Ion Chromatograph (AIM-IC) system, an instrument developed by URG Corp. and Dionex Inc. for simultaneous hourly measurements of the water-soluble chemical composition of atmospheric fine particulate matter (PM(2.5)) and associated precursor gases. The sampling assembly of the AIM-IC consists of an inertial particle size-selection assembly, a parallel-plate wet denuder (PPWD) for the collection of soluble gases, and a particle supersaturation chamber (PSSC) for collection of particles, in series. The analytical assembly of the AIM-IC consists of anion and cation IC units. The system detection limits were determined to be 41 ppt, 5 ppt, and 65 ppt for gas phase NH(3(g)), SO(2(g)), and HNO(3(g)) and 29 ng m(-3), 3 ng m(-3), and 45 ng m(-3) for particle phase NH(4)(+), SO(4)(2-), and NO(3)(-) respectively. From external trace gas calibrations with permeation sources, we determined that the AIM-IC is biased low for NH(3(g)) (11%), SO(2(g)) (19%), and HNO(3(g)) (12%). The collection efficiency of SO(2(g)) was found to strongly depend on the composition of the denuder solution and was found to be the most quantitative with 5 mM H(2)O(2) solution for mixing ratios as high as 107 ppb. Using a cellulose membrane in the PPWD, the system responded to changes in SO(2(g)) and HNO(3(g)) within an hour, however for NH(3(g)), the timescale can be closer to 20 h. With a nylon membrane, the instrument response time for NH(3(g)) was significantly improved, becoming comparable to the responses for SO(2(g)) and HNO(3(g)). Performance of the AIM-IC for collection and analysis of PM(2.5) was evaluated by generating known number concentrations of ammonium sulfate and ammonium nitrate particles (with an aerodynamic diameter of 300 nm) under laboratory conditions and by comparing AIM-IC measurements to measurements from a collocated Aerosol Mass Spectrometer (AMS) during a field-sampling campaign. On average, the AIM-IC and AMS measurements agreed well and captured rapid ambient concentration changes at the same time. In this work we also present a novel inlet configuration and plumbing for the AIM-IC which minimizes sampling inlet losses, reduces peak smearing due to sample carryover, and allows for tower-height sampling from the base of a research tower.