Estimated heavy metal emissions to the atmosphere due to projected changes in the Brazilian energy generation matrix

An estimate of heavy metals emissions to the atmosphere due to the projected changes in the Brazilian energy generation fuel matrix is presented. Present use of fossil fuel combustion for energy production is projected to increase from the present 14.5% to 29.6% of the total energy generation in Brazil in 2005. Most of this increase will be based on coal- and natural-gas-burning plants. The changes will result in an increase of about 100% in the average emissions (in tons year⁻¹) of As (9.4 to 17.7), Cr (7.0 to 16.6) and Hg (2.4 to 4.1), 50% of Cd (1.2 to 1.8), and 20% of Ni (101 to 123) and Pb (23.3 to 29.9). Although relatively small for most heavy metals when compared to other industrial sources, the changes in the energy matrix will be particularly important for Hg, reaching a maximum emission of 12 tons (t) year⁻¹, representing 15% of the total emissions of Hg to the atmosphere in Brazil. The use of Brazilian coals and the location of most coal-burning plants in a relatively small region in the south of the country strongly suggest that monitoring programs should be implemented during the building of the new plants. At a regional level the expected increase in Hg emissions to the atmosphere due to coal burning in Brazil, although small relative to North America and Europe, will equal the total amount estimated for South and Central America.     

火灾过程中火源热释放速率模型及其实验测试方法

详细分析了目前常用的火源热释放速率模型，并对其特点和参数范围进行对比讨论；同时还介绍了基于氧消耗原理的热释放速率测试方法和基于质量损失速率的热释放速率测试方法，并给出了部分实验测试结果。     

油田开发过程中事故环境风险评价

油田开发建设过程中往往会存在某些事故隐患。通过对这些事故发生的原因、几率及后果的分析 ,认为地下管道泄漏是油田生产中比较严重的事故 ,一旦发生 ,便会给生产和生活带来重大的影响。为此 ,采用地下水中污染物运移模型对泄漏油类污染物迁移行为进行了预测 ,并提出了一些可行的事故预防措施     

井下作业温度对事故影响关系的灰色关联分析

笔者基于灰色系统理论 ,结合煤矿井下运输生产实际 ,建立了以死亡人数为参考数列、以不同作业温度为比较数列的灰色关联分析体系。通过对构造的不同数据列的无量纲化处理、求取差序列 ,计算灰色关联系数等 ,得到了不同作业温度对伤亡事故影响的灰色关联度 ,并据此分析结果而找出了井下作业温度对死亡事故的影响关系 ,为预防事故发生、减少伤亡损失及改善作业环境提供了有用的依据     

注浆减沉机理的新认识和注浆系统可靠度分析

笔者通过对影响注浆减沉技术效果的分析 ,建立了由浆体单元、钻孔单元、围岩体单元和封孔单元组成子系统的注浆减沉系统 ,以及系统对应的可靠度分析模型 ;运用可靠度理论 ,解析并得出了注浆减沉系统可靠度计算公式 ;依据建立的注浆减沉系统模型 ,借助数理统计和随机过程等工具 ,可以做到比较准确地预测注浆减沉的效果 ,优化注浆参数和改善注浆工艺 ,为减少地下工程开挖损害 ,保护环境和施工安全提供了新的途径。     

自然通风消除热源厂房热害的数值模拟与实践

在有余热余湿的厂房 ,大多采用自然通风。笔者采用k ε紊流模型 ,对某钢铁公司二高线厂房自然通风消除热害进行了数值模拟。将生产线上的散热量作为能量方程的附加源项 ,计算厂房内的速度场和温度场 ,优选出了该热源厂房的通风改造方案 :进风口的标高降低 2m ,在操作平台上设置开孔率为 30 %的通风栅栏板。通过对通风改造前、后厂房内温度实测值的对比 ,厂房工作区平均温度下降 5℃ ,风速由原来的平均 0 .2m/s增加到 1.6m/s,厂房内作业区的热环境有明显改善 ,防止了因热环境问题造成的安全事故 ,提高了工人的生产效率。     

Private and public interests in water and energy

Based on empirical evidence from developed, transition and developing countries, the article looks at how the introduction of private operators’ interests into the water supply/sanitation and energy sectors may conflict with public interests in socio‐economic, environmental and political dimensions. Case studies are used to illustrate the dynamics of these interactions, covering phenomena such as unsolicited proposals, misrepresentation and corruption; the exploitation of established positions by taking advantage of asymmetry of information and negotiating capacity in relation to public authorities; and exit from contracts or concessions when acceptable profitability cannot be attained. This experience indicates that the introduction of private companies into these sectors creates the permanent possibility of conflict between private and public interests. The services are too vital both socially and economically to rely on corporate self‐regulation, and countries lack effective capacity to regulate such corporations. The authors conclude that policies relying on corporate activity in these sectors are unnecessarily risky, and that policy development should focus on building strong public sector institutions to provide these services.     

Environmental assessment of packaging: Sense and sensibility

The functions of packaging are derived from product requirements, thus for insight into the environmental effects of packaging the actual combination of product and package has to be evaluated along the production and distribution system. This extension to all related environmental aspects adds realism to the environmental analysis and provides guidance for design while preventing a too detailed investigation of parts of the production system. This approach is contrary to current environmental studies where packaging is always treated as an independent object, neglecting the more important environmental effects of the product that are influenced by packaging. The general analysis and quantification stages for this approach are described, and the currently available methods for the assessment of environmental effects are reviewed. To limit the workload involved in an environmental assessment, a step-by-step analysis and the use of feedback is recommended. First the dominant environmental effects of a particular product and its production and distribution are estimated. Then, on the basis of these preliminary results, the appropriate system boundaries are chosen and the need for further or more detailed environmental analysis is determined. For typical food and drink applications, the effect of different system boundaries on the outcome of environmental assessments and the advantage of the step-by-step analysis of the food supply system is shown. It appears that, depending on the consumer group, different advice for reduction of environmental effects has to be given. Furthermore, because of interrelated environmental effects of the food supply system, the continuing quest for more detailed and accurate analysis of the package components is not necessary for improved management of the environmental effects of packaging.     

降低矿井主扇能耗及其对策

系统地论述了降低矿井主扇能耗的诸措施，并对各种措施进行理论上的分析与探讨，提出了矿井内部采取局部风流循环可降低矿井的总能量。对老矿井，开采深度大、多水平开采的矿井，采用局部风流循环，其优越性更为突出。     

开采地下水引起的地面变形及其对工程的危害

本文以实例表述了开采地下水对水文地质条件的影响，及其引起的土体变形对工程的危害。从物理和力学观点探讨了开采地下水引起土体变形的三种机制：疏干区土自重的增加；承压含水层水压力的降低；饱水区渗流场水力梯度的变化。在变形机制探讨的基础上，提出了估算开采地下水引起土体变形的力学模型。