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The risk assessment of combustible explosive dust is based on the determination of the probability of dust dispersion, the identification of potential ignition sources and the evaluation of explosion severity. It is achieved in most of cases with the two main experimental normalized devices such as the Hartmann tube (spark ignition) and the 20 L spherical bomb (with two 5 kJ pyrotechnic ignitors).Ignition energy of the 5 kJ ignitor is well calibrated and generates a reproducible ignition. But, on the other hand, this ignition is not punctual and the over pressure produced is nearly 2 bar. Moreover, the pyrotechnic igniter accelerates the combustion with multi ignition points in a large volume and that disturbs the flame propagation. In this way, this ignition source does not allow to analyze the combustion products because the composition of the pyrotechnic igniter was found in the combustion products.This paper deals with the comparison of two ignition sources in the 20 L spherical bomb. Different explosive dusts of great industrial interest are studied with electrical and pyrotechnic ignitors, in order to understand, first, the influence of each type of igniter on the explosion behaviour and then to evaluate the possibility of establishing a correspondence between parameters obtained with these two ignition sources.Severity parameters of nicotinic acid, aluminium powder and titanium alloy were measured by using the two types of ignition system in our 20 L spherical bomb equipped with the Kühner dihedral injector. The explosion overpressure and the rate of pressure rise were measured in a large range of concentration allowing to propose correlations between electrical and pyrotechnic ignition for each parameter and each type of powder. These correlations aim to link the tests used with two different collections of experimental parameters for the same dust. The relevance of these correlations will be discussed. 相似文献
954.
Closed-loop recycling of steel in automobiles is particularly difficult because of the low tolerance for impurities and the use of composites of various types of steel products. Technologies that reduce impurities or increase impurity tolerance must be developed and introduced to the steel recycling system at the appropriate time. This study evaluated the feasibility of closed-loop recycling in the automobile industry in China. Material pinch analysis combined with dynamic modeling of the life cycle of steel sheets used in the manufacture of automobiles was employed to estimate the amount of steel sheet scrap available for closed-loop recycling and the amount of copper contamination in the scrap. The results indicate that by 2050, more than half of the old steel sheet scrap generated annually will have to be down-cycled because of its high copper contamination. However, scenario analyses of three types of technologies for mitigating the problem of copper contamination showed the potential for increasing the amount of old scrap used in closed-loop recycling. In particular, improving copper tolerance in the steel production process could be effective both now and in 2050. 相似文献
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为研究广东省“十四五”时期机动车污染减排潜力,设置3种方案进行减排分析。结果表明,淘汰老旧机动车能较好地削减机动车NOx排放量,而对挥发性有机物(VOCs)的净减排效果不佳。淘汰国Ⅱ及以下排放标准汽油车、国Ⅲ及以下排放标准柴油货车情况下,广东省各市NOx削减比例均超过10%。汕尾市、湛江市、茂名市、云浮市、揭阳市、阳江市、潮州市、清远市、河源市和梅州市淘汰国Ⅱ及以下排放标准机动车、50%国Ⅲ排放标准柴油货车能达到NOx减排10%以上的效果,而珠三角地区城市需全面淘汰国Ⅲ及以下排放标准柴油货车才能达到该减排效果。为遏制广东省O3浓度上升势头并推动其进入下降通道,要加强“油、路、车”协同管控,珠三角地区应采取比粤东、粤西和粤北地区更有力的协同控制措施。 相似文献