Experiments And Numerical Simulation Of Coal Ignition By Tiny-Oil Ignition Technology

Oil is very indigent in our country, lots of oil need import. Ignition and stable combustion in burning coal units need lots of oil. So the research of saving oil technology for boilers, to lower the cost of generate electricity, has magnitude sences for continable developing of our society economy. At present, non-oil ignition technology and tiny-oil ignition technology were mainly used to save oil in the power station. In this paper, experiments and numerical simulations are conducted for tiny oil ignition technology.In the experiments, the influence of different coal concentrations and different veloctiy on lean coal ignition in the lateral ignition tiny-oil burner were obtained. The ignition burner was identical to the burner used in an 660-MWe W-shapeboiler. As coal concentrations increased from 0.27kg/kg to 0.80kg/kg, the gas temperatures at the burner center line and 116.5mm to the burner center line decreased gradually at equivalent measuring points. The gas temperatures setting oil-guns were higher than those opposite side at the same distance to the burner exit. Coal burnout and the release rates for C and H at equivalent points at the exit decreased. O2 concentrations at the exit of the burner were 0.41-3.64%. The burner resistance because of the pulverized coal flowing and combusting were 1400-2200Pa. As the primary air velocities increased from 15m/s to 30m/s, the lateral-ignition tiny-oil burner could ignite the experimental lean coal successfully. The flames of the pulverized coal at the exit of the ignition burner were bright. At a primary air velocity of 15 m/s, the coal concentration was high and it was difficult for the pulverized coal to ignite andfor the flame to spread. When the primary air velocity was 30 m/s in the presence of coal, the gas temperatures on the side of the oil guns exceeded 900°C at some measurement points near the burner wall, and the gas temperature distribution was not the same on the two sides of the duct. The primary air velocities of 20 and 25 m/s were the most suitable.O2 concentrations at the exit of the burner were 1-3%. The burner resistance because of the pulverized coal flowing and combusting were 1300-1800Pa.Numerical simulations of pulverized coal combustion characteristics wereconducted for a three-dimensional, single central ignition tiny-oil burner used in an 800-MWe swirling boiler burning bituminous coal. The fuel comprises of pulverized coal and oil. Gaseous combustion is described by a model based on a probability density function for two mixture fractions. In numerical simulations of oil and pulverized coal burning together, the temperature peak shifted from the side of the main oil gun to the side of the auxiliary oil gun with primary air flowing toward the burner exit. The gas temperature was highest in the central area of the burner and lowest near the wall. The O2 concentration was almost zero in the central area of the burner exit. The numerical simulations agree well with experimental results, demonstrating the suitability of the model used in the calculation.