Regimes of the Combustion of Organic Coal–Water Fuels

The results of an analysis of the combustion behavior of the drops of organic coal–water fuels (OCWFs) prepared based on the flotation products (cakes) of the enrichment the coal of five grades (longflame, gas, coking, low-caking, and lean coals) and two petroleum products (petroleum residue and spent turbine oil) are presented. The experiments were performed under the conditions of the stationary fastening of an OCWF drop on the junction of a quick-response thermocouple in a flow of heated (from 500 to 1000°C) air. The following three combustion regimes were revealed for all of the test OCWF compositions: stepwise regime with slow heating (smoldering), intense gas generation regime with the boiling of liquid fuel components (boiling), and regime with a distinct tear-off zone of gas flow (torch). It was shown that the occurrence of the above combustion behaviors substantially depends on the characteristics of the OCWF components: the ash content and the yield of volatile substances of coal cakes and the boiling points and the ignition and combustion temperatures of the petroleum products used. Based on the results of the experiments, the ranges of air temperature changes characteristic of each of the three combustion regimes of fuel suspensions were established.