Calculation analysis of the effect of uneven distribution of solid fuel on burners on ecological safety of boiler plants of TPPS

Abstract

Ensuring environmental safety for energy companies in accordance with the requirements of Federal Law No. 219 of 21.07.2014 is a top priority task today. Experimental studies and industrial experience show that one of the main factors for the formation of virtually all toxic fuel combustion products in boiler plants is the ignition conditions in each burner of the furnace: the fuel-air ratio in the ignition zone, the proportion of primary air, the ratio between the secondary and primary air velocities, etc. However, according to the current regulations, the calculation of emissions of fuel oxides of nitrogen, as well as benz(a)pyrene, is based on averaged values for all burners of the furnace, and the influence of the most important factor — the uniformity of the distribution of fuel and air over the burners — on their formation is not taken into account.In the work presented, a calculation analysis is performed of the effect of uneven distribution of solid fuel on the burners of boiler plants on emissions of nitrogen oxides, as well as benz(a)pyrene, in combustion products. A calculation procedure has been developed and the dependences of the change in NOx emissions on the nonuniformity of the Δg distribution, the average air excess factor in the αG burners, the number of burners and the dust distribution models have been obtained. It is shown that with the value of the parameter Δg <10%, the uneven distribution of fuel has practically no effect on emissions of nitrogen oxides and benz(a)pyrene, and Δg5 (at which the increase in NOx emissions due to uneven distribution of dust does not exceed 5%) should make: for two burners — 22% ... 27%, four — 12% ... 22%, six — 11% ... 13%. At higher values of Δg and with increasing α, there is a significant increase in emissions of nitrogen oxides and benz(a)pyrene. It is obtained that simultaneously there is a simultaneous increase in NOx and BP. Recommendations are given on the use of dust distribution circuits and designs of dust dividers that meet the requirements to ensure that the uneven distribution of fuel over the burners would not affect emissions of nitrogen oxides.