Combustion Characteristics and NO Emissions during Co-Combustion of Coal Gangue and Coal Slime in O_(2)/CO_(2) Atmospheres

Coal slime has low ash content,and adding coal slime during coal gangue combustion may have influence on combustion character;and at this process,NO will emit,and lead to environmental pollution.O_(2)/CO_(2)atmosphere is conducive to NO emission reduction.Thus combustion characteristics and NO emissions during co-combustion of coal gangue and coal slime in O_(2)/CO_(2)atmospheres were studied.The results showed the addition of coal slime increased the combustion activity of the mixed fuels in both air and O_(2)/CO_(2)atmospheres.During co-combustion,there are synergistic effects between them at the fixed carbon combustion stage,and higher blending ratio of coal slime leads to stronger synergistic effect.Furthermore,this study also showed that with the increasing of coal slime blending ratio,the emission concentration of NO increases gradually;with the increase of temperature and O_(2)concentration,the NO emission concentration also gradually increases,and higher O_(2)concentration leads to shorter time required for the complete release of NO.Besides that,the results also demonstrate that the proportion of pyrrole and nitrogen oxide in the ashes increases with the increase of combustion temperature,and pyridine and quaternary nitrogen gradually disappear,while the total nitrogen content in ash decreases with the increase of temperature.The results will contribute to a better understanding of the co-combustion process of coal gangue and coal slime in O_(2)/CO_(2)atmosphere,and provide basic data for the practical industrial application of coal gangue and slime.

MODEL STUDY OF THE EFFECT OF SOIL NO EMISSIONS ON SURFACE OZONE

The effect of soil NO emissions on surface ozone in autumn in East China has been studied by using TCTM(Troposphere Chemical Transport Model)with the input of meteorological variables from RAMS.The chemical mechanism for ozone variation caused by soil emissions has also been investigated.The model results reveal that soil NO emissions are important to regional ozone formation and distribution and the effect of soil NO emissions shows spatial inhomogeneity.Ozone over most areas in northern China decreases with maximum average decrement reaching 5 ppb while it increases over most areas of central and southern China with maximum average increment reaching 7 ppb caused by soil NO emissions.This situation of ozone variation is mainly determined by nonlinear photochemical mechanism.For the low NOx areas(≤3 ppb),ozone increases as NOx increases;for the high NOx areas(>3 ppb),ozone decreases as NOx increases.The effect of soil NO emissions on ozone depends on the transition value and NOx concentrations.

Experimental Investigations on NO_(x) Emission and Combustion Dynamics in an Axial Fuel Staging Combustor

Axial Fuel Staging(AFS)technology is an advanced low-emission combustion method in modem gas turbine,which divides the combustor into two axially arranged combustion zones.For revealing the characteristics of axial staged combustion,an industrial-grade combustor was designed and built.The distribution of temperature and velocity field in the combustor was presented with numerical simulation.And an Atmospheric Combustor Test Rig for axial staged combustion was built.The flow resistance characteristics of the combustor were measured at first.Then the effects of the equivalent ratio and the preheating temperature on the pollutant emission and combustion instability were investigated.The results show that the total pressure recovery coefficient in cold state is always above 98%;starting the secondary combustion at low load can reduce NO emissions by 50%,and can suppress the combustion oscillation amplitude of the combustor.At the design point with φ=0.62 and preheating temperature=400°C,NO emission and CO emission are 15.68 and 4.22 mg/m^(3)(@15%O_(2)).