Ignition Temperature Of Dust Layer Research Articles

Assessment of explosion risk for wood dust in a ventilation-dust separation installation, by determining the concentration of total dust in suspension inside of the installation

Most of combustible dusts present both fire and explosion hazard. Explosion may occur at certain concentrations of dust mixed with air and in the presence of an ignition source. The threat posed by this real danger was confirmed by the events that took place in economic units such as: feed factories, wood products, textile industry, steel, etc. Among the parameters of explosiveness of combustible dust, which can cause an explosion, we mention: maximum explosion pressure, lower explosion limit, explosive index, minimum ignition energy, electrical resistivity of dust, minimum ignition temperature of dust layer and cloud, particle size and concentration of dust in suspension. The current paper presents the results of determinations of combustible wood dust concentrations, performed at an important economic unit, manufacturing veneer and wood panels, at a dusting ventilation installation composed of fan, cyclone and textile filter. These determinations were made in the pipe connecting the fan and the bag filter, to assess possible danger of explosion in the pipe, by relating the measured concentration to the lower explosion limit (concentration of wood dust).

Experimental research on combustion and explosion characteristics of medium density fiberboard on building

In recent years, the amount of medium density fiberboard(MFD) used in the construction industry is huge. The dust produced in the production has a great risk of dust combustion and explosion in different thermal runaway environment. Therefore, this paper takes the MDF dust as the research object to explore its combustion and explosion characteristics. The minimum ignition temperature of dust layer and 20L explosion vessel were used to study the changes of minimum ignition temperature(MIT) and combustion morphology of dust layer with different particle sizes of wood powder, and the influence of different influencing factors on the maximum explosion pressure was analyzed. The results show that with the decrease of particle size, the MIT decreases from 350°Cto 260°C, the maximum heating rate increases, the carbonization phenomenon becomes more obvious, and the maximum explosion pressure increases gradually; Under 200 mesh dust, with the increase of mass concentration and ignition delay, the maximum explosion pressure first increases and then decreases, and 50 g/m3 and 60 ms are the best mass concentration and ignition delay.

Study of Fire Characteristics of Industrial Dust

Abstract The article deals with the determination of fire characteristics of industrial dust samples. Particle size granulometry and determination of explosion parameters according to EN 14034 (Lower Explosion Limit LEL, Pmax, Kst) are presented. The minimum ignition temperatures of the dust layer and dispersed dust from the hot surface according to EN ISO / IEC 80079-20-2: 2016 were measured. It was found that LEL is 60 g.m−3, Pmax is 8.61 bar, and Kst is 89 bar.s−1.m. The minimum ignition temperature (MIT) of dust layer is 280 ° C and the minimum ignition temperature of dispersed dust is 400 ° C.

Analysis of minimum ignition temperature of pellet dust layer and cloud due to adding BC and ABC fire extinguishing powders

The paper describes the impact of adding fire extinguishing powders acting based on oxygen or flame on values of minimum ignition temperatures of the layer and cloud of pellet dust, and as a consequence the impact or lack of impact on values of maximum admissible temperature on external surfaces of electrical appliances working in their atmospheres. Tests were conducted of the minimum ignition temperature of layer and cloud of the agro armakow pellet dust and the agro jesień pellet dust, with and without additives of fire extinguishing powders BC Jet, BC LB2, ABC 90 and Ogniotex 103 at concentrations ranging from 5 to 70% by weight of powder contents in the mixture. Based on obtained test results it has been ascertained that type ABC powders appear to be much more effective than those type BC, because they have a much bigger impact on increasing the minimum ignition temperature of the layer and the cloud of analysed dust types. Adding only 15% of ABC 90 extinguishing powder to the agro jesień pellet has caused an increase in the minimum ignition temperature of dust layer by 80°C. The BC LB2 powder with agro armakow pellet dust has not been found to cause any changes, even at its concentration as high as 70%. The most optimum additive of powder to the biomass dust was 10% by weight of ABC powder in the mixture. At this concentration the highest increase was recorded in the maximum admissible temperature on the outer surface of electrical appliances from 235°C to 273°C.

Experimental Study Of Minimum Ignition Temperature Of Spent Coffee Grounds

Abstract The aim of this scientific paper is an analysis of the minimum ignition temperature of dust layer and the minimum ignition temperatures of dust clouds. It could be used to identify the threats in industrial production and civil engineering, on which a layer of combustible dust could occure. Research was performed on spent coffee grounds. Tests were performed according to EN 50281-2-1:2002 Methods for determining the minimum ignition temperatures of dust (Method A). Objective of method A is to determine the minimum temperature at which ignition or decomposition of dust occurs during thermal straining on a hot plate at a constant temperature. The highest minimum smouldering and carbonating temperature of spent coffee grounds for 5 mm high layer was determined at the interval from 280 °C to 310 °C during 600 seconds. Method B is used to determine the minimum ignition temperature of a dust cloud. Minimum ignition temperature of studied dust was determined to 470 °C (air pressure - 50 kPa, sample weight 0.3 g).

Experimental study on the combustion sensitivity parameters and pre-combusted changes in functional groups of lignite coal dust

Sensitivity parameters are critical for safety management and risk assessment of coal dust combustion process. In this paper, in order to evaluate the combustion sensitivity parameters and reveal the mechanism of lignite coal dust, 20L spherical explosion test apparatus and hot surface test apparatus were chosen to test the typical sensitivity parameters of lignite coal dust combustion. Results show that the limiting oxygen concentration of dust clouds (LOCC) was in the range of (13–14) %, and the minimum ignition temperature of dust layer (MITL) was in the range of (280–290) °C, respectively. The functional group variation law before combustion of lignite coal dust was tested by in-situ diffuse reflection Fourier transform infrared spectrometry (FTIR), and the proportions of functional groups in the lignite coal dust were analyzed from 30°C to 290°C. It is demonstrated that in coal dust combustion the key functional groups were CH3/CH2 and OH.

Ignition Temperature of Dust Layer and Dust Clouds of Wood Pellets

Abstract In the production, transport, storage and use of wood pellets forming a flammable and explosive dust. To assess the fire risk of wood pellets was determined ignition temperature of dust layers and dust clouds. We used two commercially produced pellets from wood waste and wood and studied the dependence of ignition temperature on the thickness of dust layer and also observed the ignition temperature dependence of dust clouds from the weight and pressure of air in combustion chamber.

Experimental Analysis of Minimal Ignition Temperatures of a Dust Layer and Clouds on a Heated Surface of Selected Flammable Dusts

Abstract The paper presents an analysis of the minimum ignition temperature of dust layer and the minimum ignition temperatures of dust clouds. Tests have been performed for selected dusts: hop, lemon balm, nettle, senna fruit, valerian, buckwheat, barley, semolina, cornflakes, oatmeal, rice flakes, flour, malt, beech, dried carrot, corn starch and sunflower husk. Tests have been performed in accordance with EN 50281-2-1. Method A consists in determining the minimum temperature at which ignition occurs of dust and/or its decomposition on a hot plate at a constant temperature. The study is used to identify the threats from industrial equipment and construction, which while working have hot surfaces, on which can create a layer of combustible dust. Method B is used for determining the minimum ignition temperature of a dust cloud or other particulate solids. Method B is complementary to the method A. It is used in relation to industrial equipment, inside which dust may exist in the form of short-term cloud.

Ignition of a dust layer by a constant heat flux

Abstract In real conditions, the surface temperature of an equipment enclosure covered with a combustible dust layer can significantly rise due to insulating properties of the dust layer. To assess this effect, the measurements of minimum ignition temperature of dust layer at constant temperature of the heated plate t t min (standard method) and the same ignition temperature at constant rate of heat generation t h min for two coal dusts were made. Dust layers of thickness between 5 and 50 mm were tested. For each dust, t t min was higher than t h min for every tested thickness of the layer. The difference was biggest for thin layers and decreased with increase of the layer thickness. The results suggest a deficiency of the standard procedure of measuring minimum ignition temperature of a dust layer.

Ignition of dust layer by constant heat flux

In real conditions the surface temperature of an equipment enclosure covered with a combustible dust layer can significantly rise due to insulating properties of the dust layer. To assess this effect the measurements of minimum ignition temperature of dust layer at constant temperature of the heated surface (standard method) and the same ignition temperature at constant rate of heat generation were made.