PCF型湿式脱硫除尘器入口结构优化

以PCF型湿式脱硫除尘器为物理模型,利用Fluent软件包,采用RNGк-ε湍流模型和SIMPLEC算法,对装置内三维流场进行数值模拟.模拟结果发现,原倾斜入口(A)的装置内烟气分布不均匀.提出了水平入口(B)、左入口(C)、右入口(D)3种优化结构,并分别对A、B、C、D入口装置内气流速度、湍流强度与压降进行了模拟分析.结果表明,C、D入口使装置内气流速度分布更加均匀,且增强了装置内湍流强度,但C入口会导致压降增加,因此最佳入口为D.最后,针对入口D装置中的低速区,模拟分析了30°、45°与54°3种不同切入角度,得出45 °效果最佳.     

Linking Fine-Scale Sub-Arctic Vegetation Distribution in Complex Topography with Surface-Air-Temperature Modelled at 50-m Resolution

This article presents the impact of the ecological investment in ironworks (dust filter installation) and construction works at a highly contaminated brownfield site on the chemical composition of household dust (HD) and street sediment (SS) in Celje, Slovenia. The evaluation is based on two sampling campaigns: the first was undertaken 1 month before the ecological investment became operational and the second 3 years later. The results show that dust filter installations reduced the content of Co, Cr, Fe, Mn, Mo, W and Zn on average by 58% in HD and by 51% in SS. No reduction was observed at sampling points in the upwind direction from the ironworks. By contrast, the impact of the construction works on the highly contaminated brownfield site was detected by a significant increase (on average by 37%) of elements connected to the brownfield contamination in SS. Such increase was not detected in HD.     

浅谈3000t/d水泥生产线窑尾收尘系统改造

介绍了南阳航天水泥厂3000t/d水泥生产线窑尾收尘系统的改造背景、技术方案、施工方案和工程造价。改造采用了在原窑尾反吹风高温玻纤袋收尘器旁并联一台同类型单排袋式收尘器的方案,以增大窑尾袋收尘器过滤面积和降低过滤风速。该窑尾收尘系统的改造取得了明显的成效。     

Per- and polyfluorinated compounds (PFCs) in house dust and indoor air in Catalonia, Spain: implications for human exposure

A total of 27 per- and polyfluorinated compounds (PFCs) were determined in both house dust (n = 10) and indoor air (n = 10) from selected homes in Catalonia, Spain. Concentrations were found to be similar or lower than those previously reported for household microenvironments in other countries. Ten PFCs were detected in all house dust samples. The highest mean concentrations corresponded to perfluorodecanoic acid (PFDA) and perfluorononanoic acid (PFNA), 10.7 ng/g (median: 1.5 ng/g) and 10.4 ng/g (median: 5.4 ng/g), respectively, while the 8:2 fluorotelomer alcohol (FTOH) was the dominating neutral PFC at a concentration of 0.41 ng/g (median: 0.35 ng/g). The indoor air was dominated by the FTOHs, especially the 8:2 FTOH at a mean (median) concentration of 51 pg/m³ (median: 42 pg/m³). A limited number of ionic PFCs were also detected in the indoor air samples. Daily intakes of PFCs were estimated for average and worst case scenarios of human exposure from indoor sources. For toddlers, this resulted in average intakes of ∑ ionic PFCs of 4.9 ng/day (0.33 ng/kg_bw/day for a 15 kg toddlers) and ∑ neutral PFCs of 0.072 ng/day (0.005 ng/kg_bw/day) from house dust. For adults, the average daily intakes of dust were 3.6 and 0.053 ng/day (0.05 and 0.001 ng/kg_bw/day for a 70 kg adult) for ∑ ionic and ∑ neutral PFCs, respectively. The average daily inhalation of ∑ neutral PFCs was estimated to be 0.9 and 1.3 ng/day (0.06 and 0.02 ng/kg_bw/day) for toddlers and adults, respectively. For PFOS, the main ionic PFC detected in indoor air samples, the median intakes (based on those samples where PFOS was detected), resulted in indoor exposures of 0.06 and 0.11 ng/day (0.004 and 0.002 ng/kg_bw/day) for toddlers and adults, respectively. Based on previous studies on dietary intake and drinking water consumption, both house dust and indoor air contribute significantly less to PFC exposure within this population.     

The simulation of long-range transport of ¹³⁷Cs from East Asia to Japan in 2002 and 2006

To evaluate the quantities of ¹³⁷Cs from past nuclear tests being transported to and deposited in Japan by naturally-occurring phenomena, the authors developed long-range transport models for ¹³⁷Cs considering Asian dust. The simulation using these models backed the observed recent increase of ¹³⁷Cs deposition along the coast of the Sea of Japan in early spring. For the sake of public safety, it is vital to ascertain whether an increase of radioactive deposition is caused by natural phenomena or a nuclear accident. The observations in recent years have suggested that dust and soil containing ¹³⁷Cs is transported from the regions around Inner Mongolia to Japan by the wind. In this paper, using observation data from the early spring of 2002 and 2006, the authors have found good agreement between the simulations and the measurements. The simulations reproduced the entrainment of ¹³⁷Cs and subsequent transport to Japan caused by strong winds associated with low pressure areas around the Inner Mongolian grasslands. The most likely cause of high-level ¹³⁷Cs deposition over northern Japan during March 2002 was ¹³⁷Cs associated with particles transported at low-altitude (1 km) and subjected to precipitation on the 22nd to 24th.     

利用高频电源提高除尘器除尘效果研究

针对锅炉静电除尘器烟尘排放浓度达不到天津市环保要求的问题,为了提高除尘器的除尘效果,通过采用将除尘器常规工频电源改为高频电源的方案,确保锅炉烟尘排放浓度最终达到30mg/Nm3的环保要求。文章分析了除尘器出口烟尘含量高的原因,阐述了高频电源的优点及在除尘器中的应用,并提出了改造技术方案。     

大型燃煤电站电袋复合除尘器的应用研究

对大型燃煤电站电一袋复合除尘技术进行了较全面的分析研究,如气流组织最优方案确定、脉冲喷吹系统选型及参数优化、粉尘荷电对滤料阻力的影响及高压电源的优选等。研究表明对电袋复合除尘器来说,袋式除尘区采用阶梯式布置是一种较为理想的气流组织方式,活塞式脉冲阀具有更好的清灰性能,粉尘的荷电有助于减小除尘设备的阻力,三相电源的性能优于单相电源。     

Air pollution assessment based on elemental concentration of leaves tissue and foliage dust along an urbanization gradient in Vienna

Foliage dust contains heavy metal that may have harmful effects on human health. The elemental contents of tree leaves and foliage dust are especially useful to assess air environmental pollution. We studied the elemental concentrations in foliage dust and leaves of Acer pseudoplatanus along an urbanization gradient in Vienna, Austria. Samples were collected from urban, suburban and rural areas. We analysed 19 elements in both kind of samples: aluminium, barium, calcium, copper, iron, potassium, magnesium, sodium, phosphor, sulphur, strontium and zinc. We found that the elemental concentrations of foliage dust were significantly higher in the urban area than in the rural area for aluminium, barium, iron, lead, phosphor and selenium. Elemental concentrations of leaves were significantly higher in urban than in rural area for manganese and strontium. Urbanization changed significantly the elemental concentrations of foliage dust and leaves and the applied method can be useful for monitoring the environmental load.     

Indoor metallic pollution related to mining activity in the Bolivian Altiplano

The environmental pollution associated with mining and metallurgical activities reaches its greatest extent in several Andean cities and villages. Many locations in this area have accumulated through centuries a large amount of mining wastes, often disregarding the magnitude of this situation. However, in these naturally mineralized regions, there is little information available stating the exact role of mining and metallurgical industries in urban pollution. In this study, we demonstrated that the various metallic elements present in indoor dust (As, Cd, Cu, Pb, Sb, Sn, Zn) had a common origin and this contamination was increased by the proximity to the mines. Lead dust concentration was found at concerning levels for public health. In addition, wrong behaviors such as carrying mining workwear home contributed to this indoor dust pollution. Consequently, the constant exposure of the population could represent a potential health hazard for vulnerable groups, especially children.     

昆明市街道灰尘粒度特征及其环境意义

对昆明市2008年1、3、4、5、7和9月份6次采集的街道灰尘样品进行了粒度分析。结果表明：昆明市街道灰尘粒度主要呈三峰特征,第一众数为65～125 μm,第二众数为3～15 μm,第三众数为0.15～0.3 μm,平均粒径范围在39.91～255.85 μm,平均值为87.1 μm,旱季（90.6 μm）大于雨季（83.7 μm）;粒度分布以正偏度为主,峰态为中等到偏窄且不对称,分选很差;与现代粉尘源区尘暴降尘的粒度分布模式高度相似,街道灰尘沉积是大气环流对远近不同距离粗细颗粒物的混合搬运的结果,应是风积作用的继续;灰尘细粒含量较高,≤100 μm的颗粒平均为635%,在适当的大气动力条件下,昆明市街道灰尘颗粒有60%～90%可以进入大气;灰尘主要来源于土壤风沙尘、建筑尘、工业烟尘和汽车尾气排放,灰尘中可吸入颗粒平均占25.2%,潜在危害性大。