Research on the Combustion Characteristics and Kinetic Analysis of the Recycling Dust for a COREX Furnace

Abstract

Thermogravimetric analysis of recycling dust (RD) from the melter gasifier of COREX, coke1 (C-1), coke2 (C-2) and coal char (CC) under 70% oxygen atmosphere was carried out using thermal balance. The chemical composition and physical structure of the samples were investigated. The characteristic temperatures and comprehensive combustion characteristic indexes were calculated and kinetic parameters during the combustion process were calculated as well using a distributed activation energy model (DAEM). The results show that the carbon in the recycling dust originates from unconsumed CC and coke fines, and the average stacking height of carbon in RD is larger than that of C-1, C-2 and CC. The conversion curves of RD are different from those of C-1, C-2 and CC, and there are two peaks in the RD conversion rate curves. The combustion profiles of RD moves to a higher temperature zone with increasing heating rates. The average activation energies of their combustion process for RD, C-1, C-2 and CC range from 191.84 kJ/mol to 128.31 kJ/mol. The activation energy for recycling dust increases as the fractional conversion increases, but the value for C-1, C-2 and CC decreases with increasing conversion, indicating different combustion mechanisms.

Analysis of Coke Oven Gas Injection from Dome in COREX Melter Gasifier for Adjusting Dome Temperature

“…In addition, the dust in the generator gas with a higher temperature could soften and bond to block the generator gas nozzle. The key factors affecting dome temperature [20], recycling dust combustion [21,22], and distribution of dome temperature [23] have been sensitively analyzed. However, COG injection from dome to adjust dome temperature has not been fully understood, particularly, the fact that COG could affect dome temperature through combustion or decomposition, without significantly changing the reducing gas composition.…”

A Mathematical Model of COREX Process with Top Gas Recycling

“…At the same time, most of the dust from the generated gas is recycled by the hot dust cyclone, which includes a large amount of carbon. [ 18 ] The carbon in the recycling dust reacts with oxygen at the dust burner, and the oxygen injected at the oxygen burner reacts with the gas. The combustion of dust and gas releases a large amount of heat, which is important for controlling the temperature of the dome.…”

Experimental Model Development of Oxygen-Enriched Combustion Kinetics on Porous Coal Char and Non-Porous Graphite

“…The calculated reaction order results are presented in Figure 5. The coal char surface area ( ) was used to determine the intrinsic reaction rate, as discussed in Equation (5). The reaction order (n) can be calculated by linearly fitting the natural logarithm value of the , and , as described in Equation (16), with the calculated reaction order for lowrank coal char being 0.51 and the value for graphite being 0.73.…”

“…Both evaporative drying technologies such as rotary drying, fluidized-bed drying, and hot-oil-immersion drying, and non-evaporative drying technologies, such as the hydrothermal dewatering, mechanical/thermal dewatering, and solvent extraction have been studied to enable the utilization of low-rank coal as a high-efficiency energy resource [3]. Various reaction models have been suggested to improve the combustion of low-rank coal [4,5]. A wire-heating reactor was used to measure the temperature of low-rank coal char, and a spot-ignition model was suggested for the evaluation of the intrinsic reaction kinetics and the prediction of the ignition temperature [6].…”