Analysis of pollutant transport in the Han River with tidal current using a 2D finite element model

Pollutant transport in the Han River, which is one of the most important rivers in Korea, was studied using the 2D advection-dispersion model developed in this research. The numerical model was developed based on the streamline-upwind Petrov-Galerkin (SUPG) where a finite element grid was used in order to treat the complex geometry of the natural water bodies. Velocity fields for the input data of pollutant transport simulation were obtained using a 2D hydrodynamic model, RMA2. The pollutant transport simulations in both the steady state flow and in the tidal currents were carried out to analyze the effects of tidal currents on the 2D concentration distribution in the region of application. The simulation results show that, with increasing water level period under tidal conditions, very large recirculation zones occurs and water flows in the upstream direction. Therefore, within the tidal currents, the polluted water goes back and forth with variations in the flow direction. As a result of this movement of pollutant, an oscillation in the concentration appears over time, which reflects both the significantly complex periodic variation in the flow pattern and large circulations.     

三峡库区万州段岸边污染混合区的计算与分析

本文采用斜分层有限元模型模拟了三峡水库蓄水前后万州江段的流速场和浓度场.通过计算龙宝河排污口和苎溪河排污口附近水域污染混合区的范围,分析比较了蓄水前后排污口的位置、水位流速变化对污染混合区的影响.结果表明,在相同的排污负荷下,排污口所处位置的不同,所形成污染混合区的范围相差很大,尤其在水库蓄水运行后这种差别更为显著,因此必须合理地规划和布置库区排污口,保证库区水体功能要求.     

1996～2000年辽阳市大气环境质量的考查

以2000年辽阳市五项大气污染物——二氧化硫、总悬浮颗粒物、氮氧化物、一氧化碳和降尘的监测数据为主,介绍辽阳市大气环境质量状况;通过对1996年至2000年五年内上述五项大气污染物的连续监测数据的比较,得知近年来辽阳市大气环境质量的发展趋势.     

最严格水资源管理制度下建设项目水资源论证若干问题探讨

在分析最严格水资源管理制度与建设项目水资源论证关系的基础上,从用水总量控制指标方面分析了建设项目水资源论证中现状用水总量折算方法;从用水效率控制指标分析了水资源论证中建设项目用水工艺参数的选取和自身用水效率;从水功能区限制纳污控制指标方面分析了建设项目水资源论证生态用水量和水功能区限制纳污影响问题。探讨新时期建设项目水资源论证相关问题,对于促进水资源可持续利用具有十分重要的意义。     

Atmospheric metal and phosphorus concentrations, inputs, and their biogeochemical significances in the Japan/East Sea

Atmospheric metals and phosphorus over the southern Japan/East Sea were investigated in order to evaluate their sources, concentrations and inputs, and to identify their biogeochemical roles in this marginal sea. Aerosols were collected on the east coast of Korea from February 2002 to April 2003 (n = 101) as well as at a remote island (Ulleung) and on a ship from February 2002 to June 2003 (n = 13). The aerosols were analyzed for Al, Co, Cu, Ni, P, Pb and Zn. Simultaneous collections of aerosols at both coast and offshore were performed, and several high dust aerosols (Al > 5 μg m^− 3) were collected at both regions. At the coastal site, both dust mineral and pollutants were transported by westerly winds from the Asian continent, but local emissions were significant (e.g., Cu, Ni, P and Zn) as well during the summer monsoon (May-August). The experimental relationships between the coast and offshore sites were defined. From these relationships, it was possible to obtain the annually averaged atmospheric metal and P concentrations over the southern Japan/East Sea, which has increased by over 2 times for the last decade. Through the estimation of atmospheric metal and phosphorus fluxes and comparisons with inputs from the Tsushima Warm Current, the atmospheric pathway was found to be a significant source for Al, Pb and Zn.     

Pollutant flushing with natural displacement ventilation

We examine the time taken to flush pollutants from a naturally ventilated room. A simple theoretical model is developed to predict the time taken for neutrally-buoyant pollutants to be removed from a room by a flow driven by localised heat inputs; both line and point heat sources are considered. We show that the rate of flushing is a function of the room volume, vent areas (A^*$A^{*}$) and the distribution, number (n) and strength (B  ) of the heat sources. We also show that the entire problem can be reduced to a single parameter (μ$\mu$) that is a measure of the vent areas, and a dimensionless time (τ$\tau$) that is a function of B, V   and μ$\mu$. Small-scale salt-bath experiments were conducted to measure the flushing rates in order to validate our modelling assumptions and predictions. The predicted flushing times show good agreement with the experiments over a wide range of μ$\mu$. We apply our model to a typical open plan office and lecture theatre and discuss some of the implications of our results.     

锅炉通风与燃烧、安全、节能及环保的关系

从理论和实践上分析了调控炉膛通风对锅炉燃烧、安全、节能和环保各方面的影响和意义,重点论述了不良通风的副作用和危害性,指明了理想的炉膛通风调控方向,可供锅炉运行人员、管理人员、安全节能环保及专业教学、研究人员参考。     

金岭铁矿建设无废矿山的实践

本文简述了建立无废矿山的必要性,着重介绍了金岭铁矿建设无废矿山所做的尝试及今后在这一方面的打算,该矿实践证明建设无废矿山是矿业实现可持续发展的重要保证。     

Grate-firing of biomass for heat and power production

As a renewable and environmentally friendly energy source, biomass (i.e., any organic non-fossil fuel) and its utilization are gaining an increasingly important role worldwide. Grate-firing is one of the main competing technologies in biomass combustion for heat and power production, because it can fire a wide range of fuels of varying moisture content, and requires less fuel preparation and handling. The basic objective of this paper is to review the state-of-the-art knowledge on grate-fired boilers burning biomass: the key elements in the firing system and the development, the important combustion mechanism, the recent breakthrough in the technology, the most pressing issues, the current research and development activities, and the critical future problems to be resolved. The grate assembly (the most characteristic element in grate-fired boilers), the key combustion mechanism in the fuel bed on the grate, and the advanced secondary air supply (a real breakthrough in this technology) are highlighted for grate-firing systems. Amongst all the issues or problems associated with grate-fired boilers burning biomass, primary pollutant formation and control, deposition formation and corrosion, modelling and computational fluid dynamics (CFD) simulations are discussed in detail. The literature survey and discussions are primarily pertaining to grate-fired boilers burning biomass, though these issues are more or less general. Other technologies (e.g., fluidized bed combustion or suspension combustion) are also mentioned or discussed, to some extent, mainly for comparison and to better illustrate the special characteristics of grate-firing of biomass. Based on these, some critical problems, which may not be sufficiently resolved by the existing efforts and have to be addressed by future research and development, are outlined.