The boiling liquid expanding vapour explosion (BLEVE) has existed for a long time and for most of this time it has been cloaked in mystery. Several theories have been put forward to explain this very energetic event but none have been proven. This paper describes a series of tests that have recently been conducted to study this phenomenon.
The study involved ASME code automotive propane tanks with nominal capacities of 400 litres. The tanks were exposed to a combination of pool and/or torch fires. These fire conditions led to thermal ruptures, and in some cases these ruptures resulted in BLEVEs. The variables in the tests were the pressure-relief valve setting, the tank wall thickness, and the fire condition.
In total, 30 tests have been conducted, of which 22 resulted in thermal ruptures. Of those tanks that ruptured, 11 resulted in what we call BLEVEs. In this paper, we have defined a BLEVE as the explosive release of expanding vapour and boiling liquid following a catastrophic tank failure. Non-BLEVEs involved tanks that ruptured but which only resulted in a prolonged jet release.
The objective of this study was to investigate why certain tank ruptures lead to a BLEVE rather than a more benign jet-type release. Data are presented to show how wall temperature, wall thickness, liquid temperature and fill level contribute to the BLEVE process. 相似文献
Habitat change in coastal Louisiana from 1955/6 to 1978 was analyzed to determine the influence of geological and man-made changes on landscape patterns within 7.5 min quadrangle maps. Three quantitative analyses were used: principal components anlaysis, multiple regression analysis, and cluster analysis.Regional differences in land loss rates reflect variations in geology and the deltaic growth/decay cycles, man-induced chages in hydrology (principally canal dredging and spoil banking), and land-use changes (principally urbanization and agricultural expansion). The coastal zone is not homogeneous with respect to these variables and the interaction between causal factors leading to wetland loss is therefore locally variable and complex.The relationship between wetland loss, hydrologic changes, and geology can be described with statistically meaningful results, even though these data are insufficient to precisely quantify the relationship. However, these data support the hypothesis that the indirect impacts of man-induced changes (hydrologic and land use) may be as influential as the direct impacts resulting in converting wetlands to open water (canals) or modified (impounded) habitat.Three regions within the Louisiana coastal zone can be defined, based on the potential causal factors used in the analyses. The moderate (mean = 22%) wetland loss rates in region 1 are a result of relatively high canal density and developed area in marshes which overlie sediments of moderate age and depth; local geology acts, in this case, to lessen indirect impacts. On the other hand, wetland loss rates in region 2 are high (mean = 36%), despite fewer man-induced impacts; the potential for increased wetland loss due to both direct and indirect effects of man's activity in these areas is high. Conversely, wetland loss (mean = 20%) in region 3 is apparently least influenced by man's activity in the coastal zone because of sedimentary geology (old, thin sediments), even though these areas have already experienced significant direct habitat alteration and wetland loss. 相似文献
ABSTRACF: Examination of a series of studies of the economically efficient water allocations in the Upper Colorado River, Yellowstone River, and Great Basins indicate that water is not a serious general physical constraint on the development of energy resources, so long as public institutions do not hinder the exchange of water rights in markets. Energy development will cause limited impacts on other water-using sectors, principally agriculture. There appears to be little reason to develop large-scale water storage facilities, even during periods of reduced water production. Water storage developments appear to be necessary only when institutional constraints severely restrict water rights markets and transfers. 相似文献
ABSTRACT: Third World irrigation and drainage systems have experienced major declines recently in both capability and performance. This is due initially to working them well beyond their design capaci-capacities; scouring, sedimentation, and overtopping result. Chronic O&M underfunding then adds heavily to this worsening malaise. International donors have assisted irrigation departments with rehabilitation projects and programs to improve O&M effectiveness on a grand (billions of dollars) scale. Despite their historical propensity to examine, almost fastidiously, program economic justifications (B/C, IRR, etc), the donors apparently have glossed over two basic analytic elements for (a) more spending on O&M as distinct from an equivalent spending on other means to provide farmers with an m3 of water; and (b) different levels of O&M spending on canals and drains. Surely those different levels provide differing benefits, in total, and at the margin. Which level is most economic? This paper identifies these latter analytical issues, posits methodologies key to an O&M spending level analysis, and discusses the information base. Particular attention is paid to identifying relevant costs and benefits, and to suggesting supplementary criteria for O&M spending level selection. The paper is an exercise in delineation of an imminently practical area of irrigation engineering economics. 相似文献
ABSTRACT: Heat pulse velocity techniques were developed for effective monitoring of water movement in aspen (Populus tremuloides), subalpine fir (Abies lasiocarpa), and Englemann spruce (Picea engelmannif). Water loss was monitored in replicated trees of each species for one year. These data were used to modify the plant activity index (a reflection of the ability of plants to transpire water at various times during a year) and the crop coefficient (a reflection of differences in consumptive use rates of water by different vegetation types when all other factors are held constant) for each species within the model ASPCON, a deterministic, lumped-parameter model describing the hydrology of aspen to conifer succession. Results of the modeling in dicate 18.6 cm net loss of moisture available for streamflow when spruce replaced aspen, and a loss of 7.2 cm when fir forests replaced aspen. The aspen to conifer successional trend appears, therefore, to be significantly reducing water yields in the western United States. 相似文献
An economic analysis of nonpoint source pollution management was conducted for the Nansemond River and Chuckatuck Creek watersheds in Southeast Virginia. The potential effects of alternative public policies on farm income, land use, and pollution loadings were investigated. Regulatory programs could have quite different impacts depending on which pollutant is targeted. Cost-share rates greater than 50 percent would have little additional effect on pollution from crop enterprises, but would reduce pollution from livestock 相似文献
The concern of this paper is with the spatial consequences of development in a given rural setting and the way in which physical planning fits into the revival of a dying rural area, particularly in Third World Countries. It is based on experience derived from Dekinal in Benue State, Nigeria and endeavours to define a rural area by briefly discussing its characteristics and highlighting its problems. It proposes a comprehensive development planning process to induce development based on available resources. 相似文献
ABSTRACT: Tradeoffs between regional economic development and resource use is a question often confronting local decisionmakers. A resource-interindustry model can be used to depict the interrelationships between regional economic sectors as to household income and/or employment and resource use. A resource-interindustry model was developed for Humboldt and Lander Counties in Nevada which shows the tradeoffs between regional household income (wages, salaries, profits, and rents) and/or employment and water usage. Water income and water employment multipliers can be ranked, enabling decisionmakers to realize sectors which require greatest regional water usage to regional household income and/or employment. 相似文献