Cement Manufacturers Association (CMA)

propagation are given, but mitigated and taken care of. The more unlikely conditions for downward propagation, with much less drive behind in it, also are given. What needs to be done here is to ensure toward the DC inlet still occurs is diverted into the atmosphere. The explosion diverter at the inlet of the DC, marked ‘2’ and ‘3’ respectively in the venting mechanism has to be self-reclosing. An explosion diverter at the inlet of the DC will be found in many coal grinding the following things will be wrong with them: - non-self-reclosing venting mechanism - wrong geometry, especially internally - in wrong position, at too long distance from the DC or otherwise wrong - not supported as for their support to withstand the enormous recoil (reaction) force in the direction opposite to the venting blast - not subject to the compulsory regular maintenance - too high activation pressure P stat Even ideally positioned explosion diverters with ideal geometry internally and externally and with a low activation front into the atmosphere completely. The low activation pressure is essential for the venting. the DC, but without high pressure behind it. The 2nd reason for the activation pressure of the explosion diverter having to be low is that this inhibits pressure piling ahead of When everything has been designed and installed correctly, but only then, the explosion vents of the DC normally can handle explosion pressure that builds up inside the DC, even when the conditions are worsened as the result of approaching - DC Most DCs have a rectangular geometry. Various versions of DCs exist. Some of them have twin bag house chambers. Especially Chinese designs have multiple funnel hoppers. The EPSR has to correspond with: a. installed capability (dimensioning and b. the explosion characteristics K St and P max of the fuel in a 21 % O atmosphere c. the geometry of the DC The K St and P max value are laboratory evaluated values. These values can only be evaluated by specialised laboratories and are mostly unknown to the coal suppliers and the users. Over the years some values for some types of coal have been found by tests of various types of coal and can be applied as rough assumptions for comparable coal. The K St unit of time under certain standardised test conditions and stands for potential violence of an explosion. The P max explosion pressure under certain standardised test conditions and also stands for potential violence. Page 40