Research Of Adjustable Furnace Temperature And Low NOx Combustion On High-efficiency Pulverized Coal Industrial Boiler

With the advantages of high efficiency, energy saving and environmentalemissions, high-efficiency pulverized coal industrial boiler is an upgraded version ofthe traditional coal-fired industrial boilers. Combustion technology is the core ofhigh-efficiency pulverized coal industrial boiler. What’s more, pulverized coalburner and furnace are the main fuel-burning equipments. In allusion to the burnerand furnace of a high-efficiency pulverized coal industrial boiler in this paper, furtherstudy was conducted by adopting the combination of numerical simulation andexperimental study methods to research the combustion characteristics.Firstly, the numerical simulation was held on a new design of the burner with aprecombustion chamber in this paper. Then the distribution of temperature and refluxzone was obtained. Studies have shown that the core temperature of the burnerprecombustion chamber who uses water is around100℃lower thanwithout water.And the hot temperature measurement was held on the burner, the measured resultsand calculated results are basically identical. At the same time, since the squeezingdegrees of the backflow zone are different. When the burner uses water, the backflowzone area and back flow of the burner are slightly larger than without water.Then this article focused on the numerical simulation of the furnace. Theresearch was about the impact on the combustion characteristics of furnace bydifferent adiabatic area, different boiler load and different burning rate of the wind.Simulation results of different adiabatic area show that the overall temperature,temperature of adiabatic section surface in the furnace, flue gas temperature atfurnace outlet, pulverized coal burning rate and the export of NOx emissions willincrease with the increase of adiabatic area when the boiler is under rated load.Compared comprehensively, the reasonable proportion of the heat shield is between20%-40%. Simulation results of different boiler load show that when the boiler loadreduces, the flue temperature at furnace outlet, the temperature of adiabatic partsurface and the pulverized coal burning rate can be adjusted to the same as the rated load as long as there is enough adiabatic area. And they can be even higher.Simulation results of different burning rate of the wind show that the NOxconcentration of the furnace can be effectively reduced after the OFA nozzles areadded. The NOx concentration decreases with the increase of burning rate of wind.When the burning rate of wind is30%, the NOx concentration at furnace outlet isonly269.8mg/Nm3and the denitration efficiency is22.28%.Finally, combustion test experiment was carried out on a4t/h pulverized coalindustrial boiler prototype. The experimental results show that the experimental dataand simulation data accord with each other. It verifies that the core temperature ofprecombustion chamber whose wall set water is around100℃lower thanwithoutwater. And the level of temperature in the furnace has been significantly improvedafter thermal baffle is installed. NOx, SO2and soot emissions in the tail flue gas aresignificantly lower than national I class area emissions standard.