An Experiment with Flame Combustion of a Mixture of Brown Coals at the Zheleznogorsk Combined Heat and Power Plant (CHPP)

The purpose of the study presented in this paper is to assess the engineering and environmental performance during the long-term operation of four BKZ-160-1.4-5 boilers on off-design fuel, consisting of 50% of Grade 2BR brown Borodino coal (with a lower heating value of Q^r = 11.3–16.3 MJ/kg) and 50% of Grade 3BR brown Bol’shesyrsk coal (Q^r = 19.3–20.1 MJ/kg) from the Kansk-Achinsk basin. The fuel-handling system operated normally with this mixture. The application of water washing eliminated any problems with slagging of the furnace water walls. Increasing the heating values of the coal mixture and the gross efficiency of the boilers reduced the total fuel consumption at the CHPPs. As a result of a decrease in heat losses with flue gases, the efficiency of boilers when operating on the mixture, according to the reported data on the CHPP performance, increased by 0.4%. These data also demonstrate that decreasing the heat losses with the flue gases increased the boiler efficiency by 0.4% when firing the above-mentioned mixture. The gross emission of nitrogen oxides remained at the same level, while the emission of sulfur dioxide increased by 40.6 t/month (14.4%) due to the elevated sulfur content in the fuel mixture. A lower ash content in the fuel mixture decreased the gross atmospheric emissions of solid particles by 15.1 t/month (25.2%), while the amount ash and slag wastes reduced by 1166 t/month (25.3%).