Technological parameters of the combustion process of brown coal in a vortex furnace

Abstract

Ukraine ranks seventh in the international list of countries by the number of coal reserves in the country. Optimal use of this natural resource is the key to active industrial development and the basis for increasing the country's energy independence. There are large deposits of coal on the territory of Ukraine, so historically this type of fuel has been the basis of the energy sector of the economy. Despite extensive experience, the optimal way to burn coal has not been established. Even minor changes in the design of solid fuel furnaces significantly affect the efficiency of the heat transfer process inside the boilers. Therefore, the study of various design features of furnaces is relevant and promising. The results of numerical calculation of the parameters of the process of burning brown coal in a vortex furnace with counter-swirling flows are presented. The fractional composition of the fuel varies from 25 μm to 250 μm. A comparison of fuel and air mixture supply schemes from the bottom of the furnace and from the top of the furnace is performed. It has been shown that the supply of fuel from the bottom of the furnace removes solid ash at the top of the furnace, leads to a more even distribution of flue gas temperatures within the furnace volume and reduces coke content in fuel particles during lignite combustion. The results of numerical simulation of brown coal combustion processes in a vortex furnace with counterflows show that among the three schemes considered, the third scheme with lower fuel supply and removal of solid ash from the top of the furnace has the best characteristics. In this case, 99.4% of the capture of particles is provided, the particles do not accumulate in the furnace volume due to the extraction of ash. However, the mechanical underburning of coke particles with a diameter of 25 μm to 250 mm, which is captured, is 8.1% and requires afterburning. The second scheme does not provide efficient combustion of coal due to the accumulation of particles in the furnace volume.