Enhancement of stability of ignition and burning of high-moisture coal in the furnace of the power boiler

Abstract

The use of high-moisture coal with a moisture content Wr> 40% as fuel requires additional burning of a more expensive reactive fuel (gas or fuel oil support flaming), caused by the need to maintain a steady ignition and efficient burning of low-grade solid fuel. In this paper, a complex approach to the modernization of the technological scheme for the burning of Tulgansky brown coal (coal rank B1) with Wr > 50% is proposed. It is supposed to improve the furnace aerodynamics, replace the pulverized-coal burners, perform refractory lining of water walls at the burner level, intensify the preliminary drying of the coal in the drying duct. Drying and burning of brown coal in the modernized scheme was studied by computer simulation in the software product ANSYS Fluent using boiler installation TP-14A as an example. The adequacy of the developed computer model was verified by comparing the results of numerical simulation with the results of full-scale tests and thermal calculations of the boiler TP-14A with the basic combustion scheme.The results of the simulation showed the possibility of stable burning of coal without gas support flaming. Reduction of fuel humidity before the mills was 4%,carbon-in-ash loss was 1.2%, concentration of nitrogen oxides in flue gases 300 mg/m3.