Study On Flame Change Characteristics Of Air/oxy-fuel Combustion In Furnace

Oxy-fuel combustion technology developing under the background of the global efforts to reduce the emission of greenhouse gases and pollutants. In oxy- fuel combustion the CO2 concentration can be more than 80%,which is useful to CO2 capture and control the emissions. The flame in the furnace contains a large amount of information, we can reveal the combustion condition according to the change of flame characteristic, and based on the qualitative and quantitative analysis of the image of flame to characterize the behavior of combustion in the furnace. So to carry out the research of flame image detecting of oxy-fuel combustion, can provide a theoretical basis for the control and regulation of oxy-fuel combustion.In this paper, we use the first full flow oxy-fuel combustion test/demonstration system as the platform, install the visual detection system in the oxy-fuel combustion test furnace, by using C++ program to segment the flame image and detect edges to obtain the value of flame characteristics.Using the flame image processing technology, study and compare the geometry characteristic and brightness characteristics of flame.Considering the difference between air-fuel combustion and oxy-fuel combustion technology, the characteristics of flame in the furnace will have great changes in the process from air combustion switching to oxy-fuel combustion. This paper selects the process from air combustion switching to oxy-fuel combustion,fuels of oil in air-fuel combustion and oxy-fuel combustion, fuels of oil/pulverized coal and coal and oil mixture in air fuel combustion, different fuel gas circulation rate, different oxygen rate,different feeding frequency are analyzed in oxygen-fuel combustion.we get that the intensity of the fire burning oil is greater than that of pulverized coal combustion, the relationship of combustion intensity is oil>coal>their mixtures when the fuel are oil/pulverized coal and their mixtures, the intensity of oxy-fuel combustion is weaker than air-fuel combustion in the same oxygen level, and with the increase of oxygen content, the intensity of oxy-fuel combustion increased, when the oxygen content is 28%-30%,the combustion characteristics in oxygen combustion is similar to air-fuel combustion. The combustion intensity decreased with the increase of flue gas circulation rate. The larger feeding quantity will not only make the combustion more smoothly but also make combustion is more stable.