Prevention of Primary Explosions of Large-tonnage Gas Drying Plants of Coal Preparation Plants
Drying installations of coal-washing plants of Kuzbass from 1953 to 1984 exploded with a frequency of 10-12 years. Before the primary explosion inside the large-tonnage gas dryers the coal had been on fire. The threats of hazard of the primary explosion: coal deposition, spontaneous combustion, prolonged burning of coal. Causes: initial humidity is higher than the norms of the regime map; the temperature of gases behind the drying equipment is above the self-ignition temperature; large amount of sucked (drawn in) air; human factor. Regimes without the seat of fire and with the seats of fire combine the boundary oxygen content. Hazard risk indicators: initial humidity of coal; the norm of the sucked (drawn in) air; the temperature behind the drying equipment, in front of the induced-draft fan; boundary oxygen content. The mathematical dependencies were studied concerning the hazard threat indicators, the parameters of the control nomograms (air suckers, boundary oxygen content, etc.) on the parameters measured online - standard (at routine testing) and instrumental. The algorithms for calculating productivity, the articles for thermal and material balances are compiled: the efficiency of the drying plant, heat generator. The method is developed for building nomograms of the harmonization of initial and final coal moisture, gas temperatures. The frequency is substantiated concerning the routine tests, including checking the state of the main and auxiliary equipment, instrumentation and automation devices. The requirements are developed and implemented, which are additional to the traditional safety rules; territorial normative documents, address technical requirements. In the column «Chronicle of accidents» of the journal «Occupational Safety in Industry» there have been no reports of explosions of large-capacity gas dryers in Kuzbass since 1985. The concept of warning primary explosions - ranges of hazard threat indicators in the regime maps exclude the formation of coal deposits, spontaneous combustion, prolonged burning. Ranges of hazard threat indicators in regime maps are calculated on the innovative nomograms using the results of the periodic regime tests. The online operator ensures compliance of the hazard threat devices with the ranges of regime maps, constantly monitoring the indications of the standard instruments, regulating the temperature of the drying agent and the load.