On the explosion and flammability behavior of mixtures of combustible dusts

In the work presented in this paper, the explosion and flammability behavior of combustible dust mixtures was studied. Lycopodium, Nicotinic acid and Ascorbic acid were used as sample dusts.In the case of mixtures of two dusts, the minimum explosive concentration is reproduced well by a Le Chatelier's rule-like formula, whereas the minimum ignition energy is a linear combination of the ignition energies of the pure dusts.An unexpected behavior has been found in relation to the explosion behavior and the reactivity. When mixing Lycopodium and Nicotinic acid or Ascorbic acid, the rate of pressure rise of the mixture is much higher than the rate of pressure rise obtained by linearly averaging the values of the pure dusts (according to their weight proportions), thus suggesting that strong synergistic effects arise; but it is comparable to that of the most reactive dust in the mixture.The observed behavior seems to be linked to the presence of minerals in the Lycopodium particles which catalyze oxidation reactions of Nicotinic acid and Ascorbic acid, as suggested by TG analysis.In the case of mixtures of three dusts, a similar behavior is observed when the concentration of Lycopodium is twice that of the other two dusts.     

Experimental and numerical investigation of constant volume dust and gas explosions in a 3.6-m flame acceleration tube

This paper describes an experimental investigation of turbulent flame propagation in propane-air mixtures, and in mechanical suspensions of maize starch dispersed in air, in a closed vessel of length 3.6 m and internal cross-section 0.27 m × 0.27 m. The primary motivation for the work is to gain improved understanding of turbulent flame propagation in dust clouds, with a view to develop improved models and methods for assessing explosion risks in the process and mining industries. The study includes computational fluid dynamics (CFD) simulations with FLACS and DESC, for gas and dust explosions respectively. For initially quiescent propane-air mixtures, FLACS over-predicts the rate of combustion for fuel-lean mixtures, and under-predicts for fuel-rich mixtures. The simulations tend to be in better agreement with the experimental results for initially turbulent gaseous mixtures. The experimental results for maize starch vary significantly between repeated tests, but the subset of tests that yields the highest explosion pressures are in reasonable agreement with CFD simulations with DESC.     

除尘器除尘效率测定误差理论的研究

全面地分析了除尘器的除尘效率测定误差产生原因，推导出在一定条件下除尘效率测定误差理论计算公式，经实例验证与理论符合。并得出在采样气体状态参数和环境条件一定时，除尘效率的测定误差主要取决于取样时间及流量。当取样时间在（１０～１５） ｍｉｎ 和流量（１０～１５）ｌ／ｍｉｎ时，除尘效率测定误差可控制在±６％ 左右     

尘肺病危险环模型与尘肺病预防对策

介绍了尘肺危险环模型的结构、原理,并以尘肺危险环模型为基础,从呼吸性粉尘危害程度分级、呼吸性粉尘监测与治理及呼吸性粉尘管理等几个方面探讨了尘肺病的预防对策。     

纺织厂地下尘室火灾危险及其防治

纺织厂地下尘室是着火最多又不易扑救之处。本文介绍了沉降式和网罩过滤式、布袋过滤式尘室,同时分析了粉尘爆炸的特点、条件及防止其爆炸、火灾的方法。     

多级除尘系统设计中的参数优化

在多级除尘系统设计中 ,应用灰色关联法进行除尘器优选 ,通过系统管路并联分流 ,将一部分粉尘直接进入二级除尘 ,降低了一级除尘器压损 ;在满足系统除尘效率的情况下 ,确定了除尘器经济入口风量 ,使系统经济运行     

对莲花山铜矿选矿车间粉尘的检测与治理

介绍了选矿车间的粉尘检测情况。根据检测中发现的问题,对现场粉尘提出了治理措施并进行了改造,改造后现场情况有所好转。     

高梯度磁除尘的实验研究

对磁性粉尘和非磁性粉尘进行了磁分离实验研究。结果表明,对磁性粉尘,磁除尘效率可达99％以上,而对非磁性粉尘,通过粉尘上磁,磁除尘效率可达90％以上。     

Electrostatic ignition hazards in insulating or dissipative tubes and hoses for pneumatic transfer of powders—Measurements and model calculations

When transferring powder through pipes or hoses made from insulating material, propagating brush discharges cannot be excluded. To calculate the limit value of the resistivity of the insulating material, below which no propagating brush discharges will occur, the charging current due to the powder transfer must be known. This charging current has been determined experimentally. Based on analytical calculations and computer models limit values for the resistivity of the hose material are derived from these experiments.     

Correlation of pmax and KSt to specific surface area and calorific value of a dust

The safety characteristics p_max and K_St of a flammable dust are usually determined in a closed apparatus (20 l- or 1 m³-vessel). The results are strongly influenced by the parameters of the apparatus (e.g. the volume, geometry, dispersion system). The aim of this project is to investigate whether there is a correlation between p_max and K_St on the one hand and the calorific value H_S and the specific surface area S_m of the dust on the other. In an experimental study, around 200 dust samples from different sectors of industry will be analysed. The analysis of around 102 dusts shows that the correlation may be described by a logarithmic function. Owing to differences in reaction mechanism it is reasonable to formulate different functions for different substance groups (e.g. metals, organic materials). This may lead to an algorithm which can predict p_max and K_St from H_S and S_m within a defined range of error.