建筑物布局对街道交叉口内气流和污染扩散的影响

采用Fluent软件对7种不同建筑物偏移量Δy(Δy=0、1/6 W、1/3 W、1/2 W、2/3 W、5/6 W和W,其中:W为街道宽度)下的交叉口内气流和污染扩散进行了三维数值模拟.模拟结果表明,建筑物偏移量对交叉口内气流运动和污染扩散具有显著影响.1/6 W的偏移量已足以在侧向街道内产生明显的次生流;当偏移量由1/6 W增加到1/3 W时,侧向街道内的速度场显著增强;而当偏移量分别为1/2 W、2/3 W、5/6 W和W时,侧向街道内的风速已与上风街道内的风速相当.随偏移量的增加,侧向街道和交叉口的空气交换增强而下风街道与交叉口的空气交换减弱.随着偏移量的增加,从上风街道尾端点源扩散到侧向街道内的污染物增加.     

Impacts of Synchronous Combustion of Small Amounts of Coal Particles with Natural Gas on Enhancing Radiative Characteristic and NOx Flame Pollutant Emission

Radiation is the most important regime of heat transfer of a flame which is directly affected by temperature and emissivity coefficient of the flame. Natural gas has a nonluminous flame, although, the flame temperature is high, but, the emissivity coefficient of the flame is small. In this paper the impacts of synchronous combustion of small amounts of anthracite coal particles with natural gas on the detailed emissivity coefficient of the flame, radiative species and pollutant emissions were investigated experimentally and numerically. A sprint CFD code was used in numerical solution and the pollutants were measured by a Testo 350XL gas analyzer. The results showed that a small amount of coal particles injected into the hot flame of natural gas increases the volume distribution and radiation view factor of high‐emissive intermediate solid soot particles in the flame which enhances the total flame emissivity coefficient. Also, coal particle injection leads to a decrease in the upstream flame temperature and an increase in the downstream region creating a more uniform temperature distribution and decreases the concentration of thermal NO pollutant of the natural gas flame. Furthermore, the role of solid soot particles on the total emissivity coefficient is remarkable, while an increase in CO₂ and H₂O concentrations has an insignificant effect on the flame emissivity coefficient.     

Idea,process and analyses of hydrogen production from atmospheric pollutant

With the considerable amounts of Sulfur dioxide (SO₂) discharged from the sulfuric acid production unit of the Tunisian Chemical Group (TCG), questions have arisen regarding the treatment of this very dangerous atmospheric pollutant which is crucial. Here, we used SO₂ to produce hydrogen. Sulfur dioxide was fed into a PEM electrolysis, the dissolved SO₂ was oxidized at the anode to produce sulfuric acid, whereas hydrogen was produced at the cathode. By measurements on site complemented by mass balances, we determined the quantities of sulfur dioxide regenerated in the atmosphere. We focused on the startup stage which is the most polluting as the amount of sulfur dioxide generated during this step is enormous. By simulation with Aspen Plus we found that two processes were possible to realize this idea; one with absorption and the other with compression. The same software was used to determine the operating parameters that can run the processes, taking into account the permissible level of SO₂ released into the atmosphere and the production of the highest amount of hydrogen. After a comparative study between the two processes, we selected the process with absorption. An exergetic study was conducted. The exergy loss of the absorption process was equivalent to 563 kJ/mol of H₂. This amount is low compared to other methods. The results show that the new process has the highest exergy efficiency (η_Ex = 90%). This was achieved through Life Cycle Analyses (LCA) which showed that the process with absorption had the highest impact on marine aquatic Eco-toxicity, whereas other impact categories were relatively insignificant.     

脱硫系统不设烟气再热器方案探讨

脱硫系统较多采用设置烟气再热器（GGH）方案。GGH可以降低吸收塔的入口烟温,提高烟囱出口烟温和烟气抬升高度,但也存在初投资大、运行维护费用高等问题。为此,从技术、经济及环保角度对脱硫系统GGH设置与否进行了比较,探讨了不设GGH方案的可行性,并给出了相关建议。     

垃圾与煤流化床混烧及其排放特性

系统地分析了流化床垃圾焚烧炉技术特点,包括锅炉的结构特点、焚烧污染物控制、以及垃圾和煤流化床混烧技术优势.垃圾和煤混烧可有效地抑制和减少二噁英的生成和排放.对1台300 t/d垃圾和煤混烧的流化床锅炉的排放特性进行了测试和分析,试验结果表明,垃圾和煤流化床混烧后污染物排放可以达到国家标准要求.     

发展动力煤洗选提高商品动力煤质量

对近几年中国商品动力煤质量(包括硫分、灰分、发热量)情况进行了统计分析,结果表明,中国商品动力煤平均硫分为0．8％,平均灰分23．0％,多数动力煤直接燃烧(无脱硫和除尘)会超标排放。要满足国家大气污染物排放标准,必须在发展脱硫技术的同时,大力发展动力煤洗选。     

低毒溶剂型接枝氯丁粘合剂的研制

研究了低毒溶剂型橡胶接枝胶粘剂的混合溶剂的组分与配比。     

Trace elements in faba bean (Vicia fabaL) plant and soil as determined by atomic absorption spectroscopy and ion selective electrode

Trace (Ag, Au, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr and Zn) and macro (Ca, K, Mg and Na) element concentrations were determined by atomic absorption spectrophotometry, and chloride by an ion selective electrode, in different parts of the faba bean (Vicia faba L) plant. Leaf, stem, pod, pericarp, cotyledon, testa and seeds were all analysed as were soil samples taken from the immediate vicinity of the plant roots at depths of 10, 30 and 60 cm before and after planting the bean plant. The experiment was situated on the shores of the High Dam Lake in Aswan (Egypt). The bean leaves showed the highest concentrations of Ca, Mg, Fe, Sr, Mn, Ni, Co, Pb and Cr while the seeds showed the highest concentrations of Zn and Cu. The highest levels of trace elements in the soil were found at 60 cm depth after planting which suggests the uptake of most trace elements by the plant is from the 10–30 cm depth zone. Statistically there were significant correlations between trace element concentrations in the bean and soil samples. The levels of trace elements in the bean under study were not considered to be toxic for man or animal uses. © 1998 SCI.     

关于环境影响评价与排污许可制度衔接的几点建议

环评与排污许可的紧密衔接,能充分发挥环境影响评价从源头上预防环境污染和生态破坏的作用,是构建以排污许可制为核心的固定污染源监管体系的重要保障.本文将对两者衔接过程中暴露出来的问题进行深入探讨,并对其如何实现紧密衔接提出一些建议,以期使两种制度相互融合,简化管理程序,同时也减轻企业的负担.     

Enhanced oxidation of toxic effluents using simultaneous ozonation and activated carbon treatment

Chemical oxidation and adsorption are feasible options to treat toxic effluents; however, the lack of empirical design data impairs their implementation at industrial scale. This paper reports experimental results on a detoxification system based on enhanced oxidation using ozone in the presence of activated carbon. The study focuses on four representative model toxic phenolic compounds, i.e. 3-chlorophenol, 4-chlorophenol, 2-methoxyphenol, and pyrocatachol. The experimental system consisted of a 1·5 dm³ stirred reactor and an ozonizer with a mean production capacity of 0·1 mmol O₃ s⁻¹ from pure oxygen. Adsorption and absorption processes were studied in the absence and presence of chemical reactions at pH 2, within the temperature range 15–35°C and solid/liquid ratio 0·05–0·005 w/w. Results showed that all these contaminants are readily oxidized by ozone, with a pseudo-second order rate constant in the range 0·02–0·08 mmol⁻¹ dm³ s⁻¹ at pH 2 and temperature 15–35°C. Fast phenolic oxidation reactions at the gas–liquid interphase increased the ozone absorption rate by a factor of 3–10, as compared with physical absorption only. The presence of activated carbon during ozonation significantly improved ozone selectivity. Adsorption isotherms and ozone self-decomposition data are also reported. ©1997 SCI