Substantiation of Practical Recommendations on the Organization of Optimal Modes of Preliminary Heat Treatment and Combustion of Coal in a Pulverized State

Abstract

Based on the data on the reactivity of coal, a calculated justification of the requirements for the organization of its preparation and combustion processes was carried out, taking into account the initial quality and operating modes of the preparation systems and combustion devices of power steam boilers. The relationship between such operating parameters of the device for preliminary heat treatment of coal as the size of pulverized coal particles, temperature and duration of treatment with the quality of the source fuel has been established in order to ensure stable ignition and completeness of burnout of the products of thermochemical transformation of coal in the conditions of the furnace chamber of the boiler unit. The results of the cycle of analytical studies are summarized and brought to the level of engineering methodology (in the form of a nomogram), which allows determining the optimal values of temperature and time of the process of preliminary heat treatment of coal before combustion in the furnace chamber of a steam boiler based on the known characteristics of the initial fuel (reactivity and particle size). The found operating parameters of the device for preliminary heat treatment of coal ensure the performance of verification (thermal) and design calculations of real fuel-using installations, for example, fuel-free kindling and dust preparation systems. It is established that the most optimal mode of preliminary heat treatment of brown Kansk-Achinsk coals polyfraction, in terms of the efficiency of ignition and combustion of heat treatment products, is 800–850°C with a processing time of 0.6–1.2 s. The results of the calculated studies were confirmed during experimental work on a special laboratory stand, which provides a mode of preliminary heat treatment of coal in a pulverized state in a wide temperature range and afterburning of dust and gaseous heat treatment products under various conditions.