C Di h Cone DischargeS Radandt S. RadandtConductive silo, grounded or insulatedHighly insulatingbulk materialCone discharges on the surface or insidegthe deposited bulk materialE < 1 JIncendive for gas-air Incendive for gas-air,vapor-airanddust-air mixturesCommon Type of Discharges: Conical Pile Dischargesdust-air mixtures.- Keep silo diameter small - Keep silo diameter small.- Keep powder resistivitybelow 1010 m(low andmedium resistivity).- Keep filling level below 50%.- Installation of grounding - Installation ofgroundingrods.Mechanical dividing of silo - Mechanical dividing ofsilo.- Phlegmatising with N2orCO2.Conical Pile Discharge: Avoidance Pure dusts with MIE >10mJ Pure dusts with MIE >10mJ (with inductance):Thoroughly groundingd and installation ofgrounding l bl (Radius 1msteel cable (8 mm in diameter) with a max. clearance to earth of1m.Conical Pipe Discharges: Avoidance by Installing Grounding Steel CablesPure dusts with MIE 10mJ (with Pure dusts with MIE 10mJ (with inductance):Thoroughly groundingand andinstallation ofinternal walls to reduce the silo diameter to reduce the silo diameter.Conical Pile Discharge: Avoidance by Mechanically Dividing the Silo Pure dusts MIE 10mJ (with inductance) or dust with Pure dusts MIE 10mJ (with inductance) or dust with flammable solvent:Thoroughly groundingd andPhlegmatising with inert gas such as CO2or N2.Phlegmatising:Adding only a certain amount ofinert gas so that theMIE ofthe product is higher than the energy releasedfrom the conical pile.Conical Pile Discharge: Avoidance by Phlegmatising with an inert gas 25LOC 700 mJ20ntration 17.516.01015en Concen Vol.%16.0510ng OxygeinCO2N200.0001 0.001 0.01 0.1 1 10 100 1000 10000Limitin0.0001 0.001 0.01 0.1 1 10 100 1000 10000Minimum Ignition Energy MIEin JExample for LEAD STEARATE: Silo Diameter 4m; MIE = 1mJ, M = 1mm; Powder resistivity 1013Ohm.mEnergy cone discharge E = 550 mJConical Pile Discharge: Avoidance by Phlegmatising with an Inert Gas Energy cone discharge ECD= 550 mJ.Large silo diameter.ECD= 5.22 D3.36 M1.46Large silo diameter.High resistivity powders.ECDis the upper energy limit ofthe conedi h i Jg y pLarge particle size discharge in mJDis the diameter ofthe silo in mMis the median ofthe particle sizedi t ib ti f th d t ig p(granules).distribution ofthe product in mmI0 298 0 435High flow velocity.D = 0.612 MIE0.298 M-0.435MIE is the minimum ignition energy ofthefine product in mJ (without inductance)Estimation of Conical Pile Discharge