Numerical simulation study on bed combustion of waste incinerator in the alpine region

Abstract

To optimize the layer combustion effect of the waste incinerator in the alpine region, the numerical simulation of a 750t/d waste incinerator in the alpine region in the three northeastern provinces of China was conducted based on the FLIC software. The simulation results show that the combustion process of waste can be roughly divided into three stages along the grate's movement direction: which are the water evaporation stage from 0m to 8.8m, the volatile emission and combustion stage from 2m to 10m, and the fixed carbon ignition and burnout stage from 2.1m to the grate's outlet. Due to the high moisture content of the waste in the three eastern provinces, the bed's height significantly decreases after the water evaporation. Because the ignition position of the fixed carbon is behind, the combustion rate of the fixed carbon is low. The primary air temperature can be appropriately increased, and the primary air distribution ratio can be optimized. In order to improve the combustion efficiency, it is recommended that the drying section provides 10 % of the total primary air volume, the volatile emission and fixed carbon combustion section provides 70 % of the total primary air volume, and the fixed carbon burnout section provides 20 % of the total primary air volume. In order to solve the problem of low fuel temperature at the grate's inlet, the direct air preheater should be used to preheat the waste before it enters the furnace to advance the ignition position of the fixed carbon and improve the burnout rate of the waste. Adjusting the angle of the front and rear arches to enhance the furnace's radiation intensity and ignition effect is recommended to accelerate the combustion speed of the waste. It is suggested that the furnace be fully insulated to reduce the heat loss and improve combustion efficiency. According to the simulation results, an optimization strategy is proposed for the operation and structure of the incinerator to achieve the purpose of optimizing combustion.