浅谈600 MW机组湿法脱硫吸收塔的设计

结合广东某600 MW机组吸收塔的设计实例,对吸收塔的结构尺寸、内部件及防腐等关键工艺设计进行了阐述,以便为国内同类型脱硫工程吸收塔的设计提供借鉴及参考.     

Use of Chitosan as Coagulant to Treat Wastewater from Milk Processing Plant

Chitosan is a natural high molecular polymer made from crab, shrimp and lobster shells. When used as coagulant in water treatment, not like aluminum and synthetic polymers, chitosan has no harmful effect on human health, and the disposal of waste from seafood processing industry can also be solved. In this study the wastewater from the system of cleaning in place (CIP) containing high content of fat and protein was coagulated using chitosan, and the fat and the protein can be recycled. Chitosan is a natural material, the sludge cake from the coagulation after dehydrated could be used directly as feed supplement, therefore not only saving the spent on waste disposal but also recycling useful material. The result shows that the optimal result was reached under the condition of pH 7 with the coagulant dosage of 25 mg/l. The analysis of cost-effective shows that no extra cost to use chitosan as coagulant in the wastewater treatment, and it is an expanded application for chitosan.     

深部岩体分区破裂化模拟试验模型几何尺寸的确定

为了揭示深部岩体在开挖时所发生的一系列变化情况,需要进行模拟试验研究。简要介绍了深部岩体在开挖洞室或巷道时发生的分区破裂化现象及其发展规律。根据分区破裂化力学现象、模拟试验背景和试验加载条件,运用弹性力学的基本理论,通过分析与计算,确定了采用b/a≥10作为模型几何参数的选取原则。在实验室条件下,可以采用石膏半径b=1 000 mm,钻孔半径a=100 mm的圆柱体模型来模拟深部岩体的分区破裂化现象及其规律。     

CITY OF TUCSON WASTE WATER EFFLUENT DELIVERY FACILITY1

ABSTRACT: The Tucson area is totally dependent on ground water, which is in increasingly short supply due to excessive overdrafts. Tucson area waste water treatment plants discharge material quantities of secondary effluent downstream, which is lost to evapotranspiration and recharge of the ground water basin. The city and the four large mining companies who share the common Santa Cruz basin ground water, recognized the common water supply problem and agreed to fund a feasibility study for mining process use of the effluent to partly alleviate the overdraft of ground water. The study analyzed the projected waste water effluent resources, potential mining company demand for waste water effluent and possible interface of an effluent delivery facility with the proposed Central Arizona Project. The effluent resources were analyzed with respect to potential demand. An optimum alignment was selected. An optimum system was detailed through design schematics, amortized cost and finance requirements, and an implementation schedule. It was concluded that a waste water effluent delivery facility could be implemented which would utilize reclaimed effluent in quantities approximating 35 percent of basin overdraft and which would provide revenue for full cost recovery over a 20 year operation period. The mining companies are studying the internal economic impacts of the project.     

固体微粒气溶胶灭火剂的改性研究

固体微粒气溶胶灭火剂作为一种新型灭火剂具有优越的抑制火灾的性能,但其应用和推广的关键在于降低灭火气溶胶形成时的温度.本文利用TG方法分析了灭火剂的热分解过程,并通过测定固体微粒气溶胶灭火剂的释放速度、释放区温度分布及灭火性能,研究了固体微粒气溶胶灭火剂的降温消焰技术.同时对气溶胶的成分和固体粒子粒度分布进行了分析.     

大气中多环芳烃气固相分配与颗粒物粒径的关系

采集了2005年5月16日～6月3日上海市桃浦地区气相样品、TSP样品及不同粒径的颗粒物样品.用GC-MS对各样品中美国EPA规定优先控制的16种多环芳烃(PAHs)做了定量分析.结果表明,大气中PAHs的气固相分配系数(KP)和各物质的过冷饱和蒸气压(pl⁰)呈良好的线性相关.多元线性回归分析表明,PAHs的气固相分配受颗粒物粒径大小的影响,粒径越大,对PAHs的气固相分配影响越大;过冷饱和蒸气压越高,气固相分配越易受到粒径大小的影响.     

Why do not all workers work? Colony size and workload during emigrations in the ant Temnothorax albipennis

Here, we study distribution of workload and its relationship to colony size among worker ants of Temnothorax albipennis, in the context of colony emigrations. We find that one major aspect of workload, number of items transported by each worker, was more evenly distributed in larger colonies. By contrast, in small colonies, a small number of individuals perform most of the work in this task (in one colony, a single ant transported 57% of all items moved in the emigration). Transporters in small colonies carried more items to the new nest per individual and achieved a higher overall efficiency in transport (more items moved per transporter and unit time). Our results suggest that small colonies may be extremely dependent on a few key individuals. In studying colony organisation and division of labour, the amount of work performed by each individual, not just task repertoire (which tasks are performed at all), should be taken into account.     

Time stress,predation risk and diurnal–nocturnal foraging trade-offs in larval prey

Insect larvae increase in size with several orders of magnitude throughout development making them more conspicuous to visually hunting predators. This change in predation pressure is likely to impose selection on larval anti-predator behaviour and since the risk of detection is likely to decrease in darkness, the night may offer safer foraging opportunities to large individuals. However, forsaking day foraging reduces development rate and could be extra costly if prey are subjected to seasonal time stress. Here we test if size-dependent risk and time constraints on feeding affect the foraging–predation risk trade-off expressed by the use of the diurnal–nocturnal period. We exposed larvae of one seasonal and one non-seasonal butterfly to different levels of seasonal time stress and time for diurnal–nocturnal feeding by rearing them in two photoperiods. In both species, diurnal foraging ceased at large sizes while nocturnal foraging remained constant or increased, thus larvae showed ontogenetic shifts in behaviour. Short night lengths forced small individuals to take higher risks and forage more during daytime, postponing the shift to strict night foraging to later on in development. In the non-seasonal species, seasonal time stress had a small effect on development and the diurnal–nocturnal foraging mode. In contrast, in the seasonal species, time for pupation and the timing of the foraging shift were strongly affected. We argue that a large part of the observed variation in larval diurnal–nocturnal activity and resulting growth rates is explained by changes in the cost/benefit ratio of foraging mediated by size-dependent predation and time stress.     

Lead particle size and its association with firing conditions and range maintenance: implications for treatment

Six firing range soils were analyzed, representing different environments, firing conditions, and maintenance practices. The particle size distribution and lead (Pb) concentration in each soil fraction were determined for samples obtained from the backstop berms. The main factors that were found to influence Pb fragment size were the type of soil used to construct the berms and the type of weapon fired. The firing of high velocity weapons, i.e., rifles, onto highly angular soils induced significant fragmentation of the bullets and/or pulverization of the soil itself. This resulted in the accumulation of Pb in the finer soil fractions and the spread of Pb contamination beyond the vicinity of the backstop berm. Conversely, the use of clay as backstop and the use of low velocity pistols proved to be favorable for soil clean-up and range maintenance, since Pb was mainly present as large metallic fragments that can be recovered by a simple screening process. Other factors that played important roles in Pb particle size distribution were soil chemistry, firing distance, and maintenance practices, such as the use of water spray for dust suppression and deflectors prior to impact. Overall, coarse Pb particles provide much easier and more cost-effective maintenance, soil clean-up, and remediation via physical separation. Fine Pb particles release Pb more easily, pose an airborne Pb hazard, and require the application of stabilization/solidification treatment methods. Thus, to ensure sustainable firing range operations by means of cost-effective design, maintenance, and clean-up, especially when high velocity weapons are used, the above mentioned factors should be carefully considered.     

爱尔兰海岸夏季空气颗粒物水溶性离子粒径分布研究

研究了爱尔兰西海岸国际海洋大气研究站夏季（2002年8月12～22日）大西洋气团颗粒物中水溶性无机离子的含量与其粒径关系.海盐成分（Cl^-、SO4^2-、Na^＋、Ca2＋、Mg^2＋、K^＋）含量在粗颗粒物中随粒径呈双峰分布（0.8～30 μm）,但Ca^2＋和K＋受陆域源影响,在亚微米颗粒区间出现另一分布峰（0.1～0.8 μm）.二次颗粒物成分在所有颗粒物中均有检出;NO^3-呈广域宽带分布,其中大部分出现在海盐主峰区（0.8～8 μm,存在Dp 1.4 μm和Dp 4.4 μm两种模态）;nss-SO4^2-（非海盐硫酸根）和NH^4＋呈相关三峰分布（Dp 0.44 μm、Dp 1.4 μm和Dp 4.4 μm）,CH3SO3-也呈相似三峰分布（Dp 0.44 μm、Dp 1.4 μm和Dp 8 μm）,三者在亚微米颗粒区间同位出现主峰.二次颗粒物成分Dp 1.4 μm模态在海岸空气颗粒物研究文献中尚少见报道.讨论了亚微米区间二次颗粒物盐类的化学形态.TSP中nss-SO4^2-、NO^3-、NH^4＋和CH3SO^3-的日均浓度分别为0.279、0.171、0.158和0.041 μg/m^3.