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Applied Chemistry and Physics
Published in Robert A. Burke, Applied Chemistry and Physics, 2020
Combustible dusts may be present in many different types of facilities. Common places for combustible dusts to be found are in grain elevators, flour mills, woodworking shops and dry-bulk transport trucks. Dusts in facilities have caused many explosions over the years that have killed and injured employees as well as firemen. An explosion occurred in a facility in Anne Arundel County, Maryland, that had many hazardous materials on-site. At first, it was thought that one of the chemicals had exploded. The fire department and the hazmat team were called to the scene. Investigation revealed that the explosion occurred in a dust collection system; it was a combustible dust explosion. Dust explosions can be prevented by proper housekeeping and maintenance practices at facilities where these types of dusts are present (Hazardous Materials Chemistry for Emergency Responders).
Comparison of Dust and Gas Explosions
Published in John Nagy, Harry C. Verakis, Development and Control of Dust Explosions, 2017
Most dust explosions in both research and industry occur when air movement or an air blast disperses dust onto an igniting source. Hence, the resulting dust-air mixtures are turbulent. The gas-air mixtures may be turbulent in industry, but in the laboratory most studies on gas explosions are made on nonturbulent mixtures. When flame develops in a turbulent atmosphere, the flame front is wrinkled. The effective area of a flame front is increased and may be as much as 8 times greater than that of a quiescent mixture. Laboratory experiments indicate that the degree of turbulence remains constant during an explosion. The effective area of the wrinkled flame front can be expressed as A = a A’, where A is the area of the wrinkled flame, a is a constant indicating the degree of turbulence, and A’ is the normal or laminar flame front area. Laboratory and large-scale tests indicate the value of a can range from unity (laminar flame front) to 8. In effect, the apparent reaction rate can be increased by a factor of 8. Generally, the value of a in dust explosion studies has a value of 3 to 6. The value of a may be determined from experiments with quiescent and turbulent gas-air mixtures. The turbulence is produced by using the dispersing system normally used to disperse dust.
Antioxidants, Stabilizers, and Fire Retardants
Published in Nicholas P. Cheremisinoff, Hazardous Chemicals in the Polymer Industry, 2017
Prevent accumulation of dust (e.g., use well-ventilated conditions, promptly vacuum spills, clean overhead horizontal surfaces, etc.). Eliminate ignition sources such as sparks or static buildup (e.g., use humidification). A properly engineered explosion suppression system must be considered where large amounts of product are handled. See standards such as the National Fire Protection Association NFPA 654, “Standard for the Prevention of Dust Explosions in the Plastics Industry”; NFPA 69, “Explosion Prevention Systems”; NFPA 68, “Explosion Venting Protection”; NFPA 77, “Static Electricity”; and other standards as the need exists. Implement other measures as the need exists.
Influences of a Pipeline’s Bending Angle on the Propagation Law of Coal Dust Explosion Induced by Gas Explosion
Published in Combustion Science and Technology, 2021
Leilin Zhang, Qianyi Yang, Biming Shi, Yihui Niu, Zheng Zhong
A pipeline explosion system composed of air distribution, pipeline, ignition, and data acquisition systems was constructed, as shown in Figure 1. The system conforms to the regulations of Dust Explosion Prevention (GB15577-2018). The air distribution system consists of a gas cylinder, a vacuum pump, an air compressor, a circulating pump, and a digital vacuum pressure gauge. The pipeline system comprises circular steel pipelines (external diameter = 200 mm and pipe wall thickness = 10 mm) with a length of 15 m and connectors with different bending angles. The ignition system is composed of a power supply, wires, electrodes, and a fuse. The data acquisition system includes a computer, a data acquisition unit (TST5206, Chengdu Test Co., Ltd.), a flame sensor (CKG100, Chengdu Test Co., Ltd.), and a pressure sensor (JAS13C2A1, Jiangsu Shuangqiao Sensor Co., Ltd.). The pressure sensor used the JAS13C2A1 high-frequency dynamic piezoresistive pressure sensor with an accuracy level of 0.5% FS and a range of 0 ~ 3 MPa. The response time and spectrum of the flame sensor are 4.5 ms and 340 ~ 980 nm, respectively. The data acquisition unit applied the TST5206 high-speed data collection unit, which has an accuracy level of 0.1% FS and a maximum sampling rate of 20 MSPS.
Multipoint radiation induced ignition of dust explosions: turbulent clustering of particles and increased transparency
Published in Combustion Theory and Modelling, 2018
Michael A. Liberman, Nathan Kleeorin, Igor Rogachevskii, Nils Erland L. Haugen
Methane–air systems are life-threatening mixtures, particularly in underground coal mines. Methane from coal mines initiated explosions, and the explosions are later escalated by coal dusts [7]. Experimental studies [8] show that particles increase the turbulent burning velocity because of the increase in the turbulence level by particle–turbulence interaction. In cases with smaller particle sizes and larger dust concentrations (> 50–70 g/m3) the turbulent burning velocity increases to be considerably larger than in cases with larger particle sizes and lower dust concentration ranges. Explosions initiated by these mixtures have destroyed infrastructure in mines and have taken thousands of lives in the past. Faraday and Lyell, who in 1845 analysed [9] one of the most destructive coal mine explosions, the one in the Haswell coal mine, had been the first who pointed to the likely key role of dust particles. In the real world, the types and nature of dust explosions are diverse. Devastating dust explosions can occur in a system of the combustible or inert particles suspended in fuel–air.
Montmorillonite Powder and Its Hydroxyl Modified Powder Experimental Study on the Inhibition of Lycopodium Powder Explosion
Published in Combustion Science and Technology, 2023
Qiyan Wu, Xiangbao Meng, Yansong Zhang, Yang Wu, Wenjiao Dai, Li Liu, Lei Shi, Tong Wang
Dust explosion is the explosion phenomenon in a limited space by the appropriate ignition energy ignition, when a certain concentration of combustible dust dispersed in a combustible environment (Zhang, Bai, and Liang 2019; Zhang, Xie, and Xu 2018). The process of dust explosion causes rapid propagation of flame in the dust cloud, along with an increase in temperature and pressure. In a confined or semi-confined limited space, the rate of release of dust explosion energy is much greater than the general combustion process, so the danger of dust explosion is enormous. The hazard of dust explosion has been a continuous threat to metallurgy, coal, grain, chemical, textile and many other industries involving the application, preparation and disposal of flammable dust. The development of the ultrafine powder industry in recent years has brought economic benefits, but also led to the frequent occurrence of dust explosion accidents (Chanthaphasouk et al. 2016; Liu et al. 2020). According to the U.S. Chemical Safety and Hazard Investigation Board of 281 foreign accident statistics, the dust explosion occurred in the most dust is wood dust, food dust, metal dust, plastic dust, coal dust, inorganic dust (Duo, Liu, and Hu 2015; Qian 2018). On May 26, 2007, a dust explosion occurred in a processing and production wood chip factory of about 200 square meters in Yangqiao Village, Luojing Town, Baoshan District, Shanghai, during the processing and production process, which resulted in 4 deaths and 5 injuries. On February 24, 2010, an explosion occurred in the fourth starch workshop of LIHUA Starch Co., Ltd. in Qinhuangdao City, Hebei Province, which resulted in 19 deaths and 48 injuries. From these accidents what can be seen that the damage caused by such organic dust explosion is serious enough. It’s of important practical significance for the prevention and control of industrial dust explosion accidents to understanding the explosion characteristics of this type of dust.