Combustion Characteristic Of Char Particles In High-pressured O₂/CO₂Atmosphere

In the current international context,the era of energy conservation has became a dominant direction.Because of combustion technical superiority of the new pressurized oxy-fuel and the superiority in trapping and sequestrating the carbon dioxide,it get more and more extensive attention in various research areas.In this paper,we do a theoretical calculation about the coal particles’ combustion characteristics under high pressure of O2/CO2to provide a theoretical basis for the application to practice of oxyfuel technology.At present stage,the theoretical calculation about combustion of pressurized oxygen is still relatively less and the combustion model of the theoretical calculations for pressurized oxy-fuel combustion is not very mature.Therefore,the selection of the combustion model becomes a difficult issue in this study.Through a series of selection among the many existing models of combustion theory, we finally select the shrinking-core reaction model for addressing these pressurized oxygen-enriched combustion problems.In this paper,we study the combustion characteristics of coal under different conditions by the reduction of the nuclear reaction model, making the temperatures、 ambient pressure、oxygen concentration and coal particle size during coal combustion to be variables parameters, striking the buring rate and burning time and other parameters of coal under different conditions. Finally we made the combustion rate and combustion time of coal to do the comparison and got some significant conclusions.By all aspects analysising the calculating data and pressurized oxy-fuel combustion technology at this stage,we draw the following conclusions which including:Increasing the combustion temperature of coal can effectively increase the combustion rate of pressurized oxy-fual and shorten the burning time, and in the case of pressurized oxy-fuel combustion temperature on combustion characteristics is more significant;With the increasing of ambient pressure,the combustion rate increased and the burning time shortened.According to the present stage of pressurized oxygen-enriched combustion studies have shown that the combustion pressure in the6-8MPa is the best results when burning;The higher of the concentration of oxygen, the higher of the burning rate of pressurized oxygen,at the same time,the shorter of the burning time.Considering the combustion characteristics and oxygen cost,30%of the oxygen concentration is the best;The larger of the coal particles, the smaller of the combustion rate and the longer of burning time. And in the case of pressurized oxy-fuel coal particle size on the combustion characteristics is more significant. Overall,the pressurized oxy-fual combustion technology reflected its great advantage both in coal combustion characteristics and the effect of energy saving,which providing the theoretical basis for applicating the pressurized oxygen-enriched combustion to practical.