| Show ous C Combustion of Coal ot otIn i In the course of bf f fa a study of tF the the spontaneous combustion of coal being bein conducted by the Bureau of Mines i Nt at its Pittsburgh h station an adiabatic calorimeter forthe has 1 Ien wen en constructed for f the purpose of st studying dying the heating ng tendencies of various va ious coal samples Ics under conditions permitting the eli eli- 1 of all variables affecting ng spontaneous com save that of oxidation itself IThe The normal heating n rate due to oxidation alone is th then obtained After once nce establishing this thil th characteristic fog foi a given coal other variables are introduced and their ef- ef c effects fec studied C ormal heating rate r ng curves cunes c have been established for coals g c of f different rank from lignite to an- an anthracite ant t Except for the semi semi-bitu- minious coals and anthracite from a n temperature t at of lp W degrees C heating rates ates are proportional to the tom tem r with bituminous bituminous anti and n anthracite the he heating rates are aie call c cally ally constant on Variation in size of e the he coal under test fest est does not affect the he shape of ot characteristic characteristic heating hetting curves arves Heating however is very much nuch intensified Iby y reduction in size si Thoroughly Thor coals heat less r rap rap- rapidly rapi i idly than containing a n little moisture I A moist coal will heat or 01 cool ool depending or on ora its iLs degree of ot satur- satur saturated relative to air which it con comes conin in Ii contract With Wit dr dry air nil and moi t coal oaI and latent neat eat of vaporization ion of if the moisture Wit taken ken to saturate the theair air may well b sufficient to over over- I lation dation oxidation overbalance I balance alance the hen hea developed by o ong |
