Experimental Study On The Burning And Explosion Characteristics And Suppression Materials Of Colored Running Powder

The colored running powder,which is also known as colorful corn flour,was mainly used in some rainbow activities and celebrations.It is because the color running powder could regulate atmosphere in entertainment activities,so before the explosion happened,color running powder mainly is used in many commercial or celebration activities.In 2015,Taiwan occurred a color powder explosion accidently,and the number of casualties reached 524,so in a long time the government prohibit the use of color running powder in celebration activities.Provided that the color running powder could play an original role without the risk of explosion,activity like color running will rise again.This paper focuses on the combustion and explosion characteristics of colored running powder and its explosion suppression materials.First of all,the physical properties of color samples were analyzed,including the distribution of particle size and element.Secondly,in order to study the combustion characteristics of colored corn flour,this paper tested the minimum ignition temperature of colored corn flour samples by using HY16429 dust cloud ignition temperature testing device,and the minimum ignition temperature of colored corn flour samples was tested to investigate the effects of dust cloud concentration,system dust pressure and color on the minimum ignition temperature.Thirdly,to study the explosive characteristics of colored corn flour and the effect of explosion suppression materials,the explosion suppression characteristics of Mg?OH?2?Al?OH?3 and NaHCO3 were investigated by using 20 L near-spherical explosion testing system.In addition,by analyzing the experimental results combined with the physical and chemical properties between the particle size and elements distribution of color running powder,the results show that:?1?Under the different dust pressure conditions,the minimum ignition temperature of dust cloud decreased at first and then increased with the increasing of dust cloud concentration,and reached the most dangerous concentration in the range of 2250-3500 g·m-3.With the dust pressure increasing under different concentration conditions,the minimum ignition temperature of dust cloud decreased at first and then increased,and in the range of 60 kPa-80 kPa it reaches its lowest value.The minimum ignition temperature was 365 ?.The ignition temperature of the colorless corn flour is generally lower than the one with pigment,and among the four kinds of corn flour which contain the pigment,the red corn flour have the largest variation of minimum ignition temperature at the concentration range of 500-4500 g·m-3.The temperature could reach to 475 ? when the cloud dust concentration was less than 1000 g·m-3,and when it reached the most dangerous concentration,the ignition temperature was 365 ?;And the minimum ignition temperature of the blue corn flour dust cloud was relatively stable with the change of the dust cloud concentration.?2?Under the dust concentration of 70 g·m-3 experimental conditions,the maximum explosion pressure of the dust cloud increased at first and then decreased with the increasing of ignition delay time,and the optimum ignition delay time was 60 ms.The maximum explosion pressure of the dust cloud increased with the initial ignition energy increasing,and minimum initial ignition energy is 4 kJ.The pressure-time curve of dust explosion is divided into pressure rising stage,the pressure peak stage and the pressure decay stage.With the dust cloud concentration increasing,the maximum explosion pressure of dust cloud increases at first and then decreases,When the dust cloud was 190 g m-3 that reached the most dangerous concentration,and the maximum value of explosion pressure was 0.368 MPa.Different color corn flour have different explosion limit,the maximum concentration of red corn flour was 70-80 g·m-3,the minimum concentration of blue corn flour was the lowest?40-50 g m-3?.?3?Three kinds of powder suppression materials Mg?OH?₂?Al?OH?₃ and NaHCO₃ can effectively inhibit the dust explosion,and the effect of explosion suppression:NaHCO₃>Al?OH?₃>Mg?OH?₂.The data and conclusions obtained in this paper can provide some theoretical guidance for the prevention of color running powder explosion,and there is an important significance to the safe production of flammable dust industry.