Using thermodynamic availability to determine the energy of explosion

Current methods to determine the thermodynamic energy of explosion are based on the Helmholtz free energy. The Helmholtz free energy represents the maximum work available from a system during a constant temperature process. For many real explosions, the material is initially at a temperature or pressure higher than the ambient environment. Thus, the Helmholtz free energy does not account for all of the energy sources. The thermodynamic availability provides a general approach to determine the maximum work available from any process. Furthermore, the availability provides a much more formal and structured method for performing the calculations. This paper provides the formal basis, demonstrates the application of availabilty using a number of examples, and provides a table of availability data.     

Halon replacement: The law and the options

Halons 1301 and 1211 have been employed widely for over 20 years in a broad array of fire and explosion protection applications. These chemicals, however, have been determined to be environmentally unfriendly due to their high ozone depleting potentials. International treaty, national laws and local ordinances have severely limited the future use of these chemicals. Production in the United States will likely come to an effective halt by 1994. A number of alternative chemicals have been suggested as potential replacements for the halons both in total flooding and streaming agent applications. A comparison of the several viable halon alternatives is made including performance, cost and availability. Areas where new applications data are required are noted.     

漳村煤矿深孔预裂爆破增透技术的应用研究

针对漳村煤矿2306工作面低透气性煤层抽采瓦斯效率低,耗工误时等问题,提出了利用深孔预裂爆破增透技术,增加煤体透气性,提高瓦斯抽采量的措施。主要探究了深孔预裂爆破增透的作用机理,以现场矿井实际应用的煤层、爆破和炸药参数为基础,对煤层深孔预裂爆破利用三维数值模拟方法进行研究。数值模拟分析得到了2306工作面瓦斯巷煤层的松动爆破半径为4m,为深孔预裂爆破试验的钻孔布置提供了理论依据;在2306工作面瓦斯巷内进行了深孔裂爆破试验,现场考察了深孔预裂爆破增透试验瓦斯抽采效果,平均瓦斯浓度较比较孔抽采瓦斯浓度提高2~4倍,平均瓦斯抽采纯量较比较孔抽采瓦斯纯量提高2~5倍,提高了煤层瓦斯抽采率,缩短了煤层预抽时间,具有显著的经济与社会效益。     

Toward universal telephone access: Market progress and progress beyond the market

The last 10 years have seen an explosion in access to telephone services worldwide based on rapid technology advance in increasingly competitive markets. The mobile phone has driven expansion in subscribers and access, especially in the developing world. This paper estimates global mobile footprint coverage based on 2002 data and calculates that as much as 77 percent of the world's population may live in an area covered by a mobile signal. Nonetheless, many people remain without access to telephony. The paper estimates the maximum likely cost in terms of cross subsidy within the industry and outside financing for achieving universal access using competitively awarded subsidies to private providers in a reformed market. This upper-end cost is estimated at $5.7 billion, with costs that could not be supplied by a reasonable tax on existing providers (and so required from outside the sector) estimated at $1.8 billion.     

Kohlekraftwerke mit CO<Subscript>2</Subscript>-Abscheidung: Strategien,Rahmenbedingungen und umweltseitige Auswirkungen

A successful implementation of CO₂-capture in power plants is mainly depending on the energy political or economical environment. The future role of lignite and hard coal power production varies widely in presumed energy scenarios. This report considers the actual projections of BDEW. Increasing demand, the replacement of old plants and the compensation of efficiency losses due to CCS-technology cause highly ambitious expansion rates, assuming a retrofit time horizon of 10 years starting in 2020. The corresponding coal demand increases strongly. Therefore, a solely concentration of CO₂-reduction potential is not sufficient. Other environmental impacts triggered through emissions are low compared to the total German impacts. Nevertheless, the compliance with national ceilings for NO_x emissions for example can only be reached by compensation measures in other sectors.     

管道输送天然气泄漏危害的定量分析

以管道输送天然气泄漏情况为模型,计算了气体泄漏以后的扩散范围和泄漏量,对火灾燃烧和爆炸后的伤害范围进行了量化分析,提出了参考风险评价结果确定安全距离,以及将普通玻璃更换为防爆玻璃,建设防护墙等建议。     

The new competition for land: Food,energy, and climate change

The paper addresses the new competition for land arising from growing and changing demand for food when combined with increasing global demand for transport energy, under conditions of declining petro-chemical resources and the urgent need to reduce greenhouse gas emissions. The paper starts from the premise of a ‘food, energy and environment trilemma’ (Tilman et al., 2009), where all demands to expand the area of cultivated land present high risks of increasing the carbon footprint of agriculture. Having reviewed the main drivers of demand for food and for liquid transport fuels, the paper weighs the controversies surrounding biofuels arising from food-price spikes, the demand for land, and consequent direct and indirect land-use change. It suggests that we need a more complex, and geographically differentiated, analysis of the interactions between direct and indirect land-use change. The paper then reviews evidence of land availability, and suggests that in addition to technical availability in terms of soil, water, and climate, political, social, and technological factors have significantly shaped the competition for land in different global regions, particularly the three major biofuel producing ones of the USA, Brazil and Europe. This point is further developed by reviewing the different innovation pathways for biofuels in these three regions. The main conclusion of this review is firstly that any analysis requires an integrated approach to the food-energy-environment trilemma, and secondly that strategic political direction of innovation and sustainability regulation are required to bring about major shifts in agriculture leading to sustainable intensification of cultivation (Royal Society, 2009), rather than the continued expansion of cultivated area. The consequent perspective is one of considerable global variety in technologies, agricultural productive systems, and use of natural resources. This contrasts sharply with the world of a dominant global and integrated technology platform based on petro-chemicals to which we have become accustomed.     

Determining the Maximum Hourly Demand of Natural Gas for Large Suppliers

This article deals with the determination of the maximum hourly energy consumption of large (municipal) natural gas suppliers using the Monte Carlo simulation method. To ensure an adequate supply for all their customers, suppliers need to purchase capacities in geological storage systems. If, due to cost considerations or inaccurate predictions, the chosen capacities are smaller than the actual consumption, additional costs are incurred for the procurement of short-term quantities of gas, e.g. from the balancing energy market. It is therefore necessary to formulate and solve an optimisation problem, which is done as described in the following by means of a simulation after modelling all required quantity values and price data. The aim is to minimise the structure costs—i.e. the fixed capacity costs and the variable balancing energy costs—by selecting the most appropriate hourly energy supply level. Since the selection of the storage capacity generally has far-reaching financial implications, the statistics-based simulation method described in the following is intended to provide the companies concerned with a reliable basis for decision-making.     

Verfügbarkeit von nicht-erneuerbaren Energierohstoffen

Crude oil, natural gas and coal currently are the most important energy sources and will be the backbone of the energy industry for the next few decades to come. The discussion about the future availability of these fossil fuels was revived by the sharp rise in energy prices since 2004 to a record high in mid-2008. This posed a question as to how long non-renewable energy resources may be available in sufficient quantities in the future. The annual report 2010 “Reserves, resources and availability of energy resources” from the Federal Institute for Geosciences and Natural Resources in Hanover analyses the global situation of crude oil, natural gas, coal, uranium and thorium. The focus is on the analysis of reserves and resources, but also aspects of production, consumption and trade as well as prices are being covered. The main emphasis is put on conventional energy resources, but also non-conventional hydrocarbons are discussed. As a result of the study, the situation for crude oil becomes increasingly critical. From a geological point of view there are still sufficient quantities of natural gas and uranium. Coal has the by far greatest long term potential, but in comparison with other fossil fuels it is more pollute.     

矿用瓦斯爆炸阻隔技术研究与发展

近年来煤炭生产任务加重,矿井开采深度增加,导致矿井瓦斯事故频发,本文对国内外瓦斯爆炸及阻隔爆技术进行了总结概述,分析了现阶段广泛应用于我国矿山的阻隔爆设施的优缺点,对一些国内外的先进阻隔爆研究成果进行了分析介绍,这些阻隔爆技术及材料能够在一定程度上为我国瓦斯灾害防治工作提供新思路、新方法。     

Pension-Plan Real Estate Investment in an Asset–Liability Framework

This study explores the role of pension-plan real estate investment in an asset–liability framework. By assuming that the pension-plan manager wishes to have assets of at least equal value to the liabilities at all points in time, an asset selection process is derived which depends on both the asset's covariance with other assets and its covariance with the liability stream. We generally find real estate not to be highly correlated with pension-plan liabilities. This finding is of general interest, since it helps to explain why pension-plan real estate investment is extremely limited and much smaller than one would expect if pension-plan investors cared only about the mean and variance of the real return to their invested wealth.     

建立上、中、下游一体化天然气工业体系问题的思考

中国进入天然气工业快速发展的时期，“西气东输”工程等建设为我国中、西部天然气大规模开采创造了极为有利的条件。上、中、下游一体化是由天然气的性质所决定的。要逐步形成全国型大供气系统，实现多气源、多通路、可靠、均衡、经济地向用户供气：要夯实资源基础：输气管道是产地和用户的纽带，它使气区内成组气田开发、大气区间勘探开发和市场配置的优化成为可能．管道的安全问题．应受到政府、企业和全社会高度重视；地下储气库的规划和建设要加强：我国长江三角洲、环渤海湾、珠江三角洲等地区有着广阔的天然气市场．天然气的利用除发电、天然气汽车外，化工利用要重视；天然气与其它能源如何合理配置要规划，中国能源发展要走多元化道路：天然气作为特殊商品必须制定相关法规、定价机制、税收政策和其它激励政策．以加速天然气工业发展．改变在我国能源消费结构中的地位。     

一种清洁能源与市政热网互补的供热系统设计及模拟研究

北方地区的建筑供暖需求随着城市建筑面积的迅速增长而不断增加,而城市热网改扩建缓慢,供热能力不足,距城区较远的新建及改扩建小区的供暖需求面临挑战,并且供暖带来的高能耗及环境污染问题日益严峻。针对此类问题,提出了将太阳能、空气能与传统市政热网相结合、互为补充的清洁能源与市政热网多能互补的集中供热系统,利用TRNSYS软件建立系统模型,设计系统5种不同的运行模式及相应的运行控制策略,并以石家庄市某新建小区为例进行分析。模拟运行结果表明,在整个供暖季中,运行时间较长的是太阳能辅助双热源(水源)热泵供热模式和双热源(空气源)热泵供热模式,清洁能源的供热比例为82.15%,热泵机组效率高,平均COP为4.06,远高于常规的热泵机组。研究结果可为周边供热能力不足的新建及改扩建小区选择供热系统提供参考。     

煤矿爆破作业中有毒气体的危害及对策

煤矿爆破作业中,炸药在释放出爆炸能的同时也产生一些有毒气体,本文论述了这些有毒气体产生的原因,对人体的危害和避免危害的对策.     

Inventory management with random supply and imperfect information: A hidden Markov model

In most of the papers on inventory models operating in a random environment, the state of the environment in each period is assumed to be fully observed with perfect information. However, this assumption is not realistic in most real-life situations and we provide a remedy in this paper by assuming that the environment is only partially observed with imperfect information. We accomplish this by analyzing two formulations of single-item models with periodic-review and random supply in a random environment. In the first one, supply is random due to random capacity of production and random availability of transportation. We show that state-dependent base-stock policy is optimal if the capacity and all costs are observed, while demand and availability are unobserved. In the second model, we consider a model with random availability only with fixed-ordering cost. We show that state-dependent (s,S) policy is optimal if the availability process is observable.     

模糊事故树法在贵州某煤矿瓦斯爆炸事故分析中的应用研究

贵州省是煤矿瓦斯事故的高发地区,瓦斯事故通常会有大量人员伤亡,造成煤矿重大经济损失,本论文运用安全系统工程的知识,把事故树和模糊数学相结合,以贵州省某煤矿瓦斯爆炸事故为案例,建立煤矿瓦斯爆炸事故分析模型,分析煤矿瓦斯爆炸事故。     

运用AHP-运用模糊数学筛选突出危险性预测敏感指标的方法研究

现场对河南某矿掘进工作面进行煤与瓦斯突出预测指标值测定,指标包括：瓦斯压力、瓦斯涌出初速度、煤的坚固性系数、煤的破坏类型和初始瓦斯释放膨胀能;运用层次分析法（AHP）首先确定指标的重要程度,再利用模糊数学综合法对煤与瓦斯突出危险性进行综合预测。利用预测结果和单项指标的符合情况来选择预测敏感指标,研究结果表明这种方法具有较强的实用性和可靠性,对煤矿突出预测敏感指标的选取具有一定的指导和借鉴意义。     

The anatomy of an acrylic acid runaway polymerization

The details of an unscheduled polymerization of acrylic acid initiated by indirect heating have been characterized by in-depth analysis of the polymer, kinetic and thermodynamic calculations, and heat and material balances on the system. The data fit together to give a consistent picture of the polymerization scenario. The fact that the acrylic acid polymerization was not violent was primarily due to the presence of about 10 ppm phenothiazine, which delayed the onset of free radical polymerization until about 2 to 3 hours after the monomer had reached its boiling point. Since much of the acrylic acid was converted to dimer during this induction period, the ultimate energy release was greatly limited. Other moderating factors were a relatively slow heatup of the tank contents in the external heat exchange recycle loop, free vapor venting, and the incursion of fire monitor water into the tank.     

Wasserstoff als Kraftstoff im Deutschen Verkehrssektor

Hydrogen is a basic product of the (petro-)chemical industry. Furthermore it can be used as a fuel for vehicles. One main advantage of hydrogen as a fuel for drive trains is the possibility to reduce greenhouse gas emissions significantly compared to fossil fuels and avoid other local emissions. Against this background, the goal of this paper is to compare fuel cells driven by hydrogen in respect of environmental parameters. The emissions of these options are not only produced during driving and therefore this paper applies a cradle to grave approach (i.e. life cycle assessment). Greenhouse gas emissions and acidification as well as nitrogen oxides are analysed. To allow a fair comparison in total ten different systems including fossil fuels are analysed (five with hydrogen and five alternatives). That includes the entire life cycle of the car (i.e. production, use, and disposal) assuming a defined amount of kilometres to be driven during the technical lifetime. For a full assessment the energy needed to produce and run the car, the fuel production as well as the fuel distribution are considered. The results show that electrical drive trains could reduce specific greenhouse gas emissions significantly if renewable sources of energy are used. For the acidification some fossil options were better than options powered by renewable energies.     

Germany’s Energy Supply

Germany has only very limited domestic energy resources. Seventy percent of primary energy needs must be covered by imports. The markets for energy are marked by a wide diversity and a large number of providers. The oil market has been intensely competitive for decades now. Lignite and hard coal are subjected to fierce substitution competition, especially with natural gas. The natural gas and electricity markets were fully liberalized in 1998. Consumers can freely choose from a vast number of suppliers. Since the beginning of this century, however, state interference particularly in the electricity market has increased. The expansion of renewables has been promoted since the year 2000 by feed-in priority and feed-in remunerations regulated by the state. The energy transition initiated in 2011 is characterized by ambitious energy and climate policy targets. Key pillars include the conversion of electricity generation from production on the basis of conventional energy sources to a system based mainly on renewable energies combined with stringent requirements designed to enhance energy efficiency and what are probably the most ambitious climate protection targets worldwide. As regards the expansion of renewables and the phase-out of nuclear energy, Germany is keeping to its target path. By contrast, there are no signs yet that the objectives formulated in terms of the lowering of primary energy consumption and the reduction in greenhouse gas emissions will be achieved.