Improving the efficiency of burning solid fuels using organic highly reactive additives

Abstract

This paper presents the results of computational and experimental studies of the effect of organic highreactive fuel additives on the combustion efficiency of high-ash thermal coal, including the environmental indicators of the process. A technical solution is proposed for the development of the technology of cocombustion of solid fuels with organic highly reactive additives (OHRA) and the creation of a specialized combustion chamber with a plasma launch system. The thermodynamic analysis and kinetic calculation of the process of co-combustion of solid fuels with OHRA were performed, on the basis of which the optimum process temperatures, air excess factor and geometric parameters of the combustion chamber were selected. Thermodynamic calculations of Ekibastuzski coal combustion showed that 7 kg of air is required for burning 1 kg of coal. With the use of OHRA, there was a tendency to increase the concentrations of CO₂, H₂O in the combustion products of coal and a corresponding decrease in the concentrations of O₂ and N₂, which indicates a slight increase in the completeness of the oxidation of carbon and hydrogen. OHRA from light ethers have a slight effect on reducing the concentration of NO. Kinetic calculations showed that the combustion process of Ekibastuzski coal (coal consumption 10 kg/h) is fully completed in a combustion chamber with a diameter of 0.2 and a height of 0.9 m. A series of 52 experiments on the co-combustion of high-ash Ekibastuzski coal with organic highly reactive fuel additives in a specialized combustion chamber was carried out. A complex of numerical and experimental studies of the combustion of high-ash hard coal in the developed combustion chamber with coal consumption up to 10 kg/h made it possible to evaluate the effectiveness of the additives Omstar-DX1 and Open Flame, which are a mixture of light esters. Comparative tests of burning coal without the use of OHRA and using OHRA with different weight ratios OHRA : coal (0–5 ml per 1 kg of coal) were performed. Experiments have shown that OHRA raise the temperature of the flame in the initial section of the combustion chamber and reduce it at the exit, which indicates an earlier ignition of the air mixture and, accordingly, more rapid burnout. Additives Omstar-DX1 and Open Flame significantly increase the efficiency of burning low-grade coal, reducing emissions of CO, NO, SO₂ and increasing the concentration of CO₂, indicating an increase in the completeness of combustion of fuel.