Mechanism And Experimental Studies Of NO_x Reduction By Coal Water Slurry Reburning

NO_x reduction through reburning was an effective pollution control technology. Its efficiency is relative to the characteristics of reburing fuels. In order to explore the probality of NO_x reduction through coal water slurry (CWS) so as to expand its applied ranges, the information about fuel-N distribution during pyrolysis, reburning knetics and its utility ranges and reburning technology features were generally studied here.Nitrogen volatilization and surface areas increase are reasonable explanations for CWS' high NO_x reduction efficiency. In the pyrolysis experiment, CWS' char-N and NH3-N fraction are lower than the coals, while Tar-N, HCN-N, and N₂, etc fractions are greater. Temperature, fuels, CWS concentration and residence time are factors influencing N volatility. BET or DR surface analysis technology confirms the effect of increase of both specific area and microcelluiar structure after CWS making.When thermogravimetry was used to study the heterogeneous reaction of NO reduction, the weigh loss of samples with temperature recorded the Char reaction process detailedly. Through tests, it is found that the reaction between NO and Char has sectioned characteristics, this maybe relative to the mineral substance in the char. Slurrying can make coal char more reactive. The kinetic data show that activation energy of reaction at low temperature often is lower than that at high temperature.Water can not play a role in NO_x reduction alone. Owning the NO_x control advantages of both coal and water, CWS showed stronger NO_x reduction ability. Relative to the condition of volatiles peak value appearance, the NO_x reduction efficiency of CWS became better at the reburning zone excess air ratio of 0.9. With the increase of reburning zone temperature and decrease of fuel particle size, the CWS NO_x reduction efficiency increased. Lower CWS concentration favored reburning zone NO_x control. Different metal additives have different NO_x reduction catalytic effects.0.25 MW down fired furnace was used to study the characteristics of CWS reburning effects, temperature field change and carbon content in the fly ash. Variables examined during these tests were main combustion zone excess air ratio, reburning zone excess air ratio, percent heat input from reburning fuel, location of reburning zone, momentum of reburning fuel and furnace load. The best NO_x reduction efficiency of CWS reburning in this paper is 81%.A numerical method can save both time and manual power, even, convinene the reburning effect test. CWS reburning model built in this paper could simulated the...