Research On Exergy Distribution Characteristics Of Coal-fired Boiler Furnace

With the shortage of supply of the fossil energy, reducing the consumption of energy, making the sustainable development becomes the main challenge of the human society. Coal-rich, oil-poor, less gas is the energy supply structure of our country nowadays, so making the good use of the coal appears extremely important. Coal-fired power plant is main link of our country coal consumption, thus it is importance that did enough researches and analysis on the energy consumption of coal-fired power plant. A model of the coal-fired power plant boiler is constructed by use of numerical simulated software FLUENT in this paper, analysis the combustion characters of the coal-fired boiler under design condition, and combines the basic theory of exergy, obtain the exergy distribution characters of exhaust gas in boiler furnace. The results indicate that, the physical exergy distribution of exhaust gas is affected by the gas temperature while the chemical exergy is mainly affected by the component of the exhaust gas. The total temperature of the boiler furnace decreases with the load reduction, the higher value is around the combustor zone, and the value is fluctuated severely, demonstrating certain energy-saving potential in this zone, and it can decrease the exergy loss by improving the type of burning. By improving the set of heat-facing at the head of furnace zone, it can reduce the exergy loss through strenthing the burning and transforming process. For different coals, the exhaust gas exergy of the combustor zone is mainly affect by the ingredients of coal. The more carbon in the coal, the value of exhaust gas exergy is higher. however, the temperature is the mainly factor in the head of furnace. The exhaust gas exergy increased by the temperature value distribution incresed. At the different load and different coal conditions, the basic idea of save energy and reduce energy consumption is improved the combustion and optimize the heat exchange. Meanwhile, referring to the theory of high temperature air combustion, raising the temperature of preheated air, the result demonstrates that the temperature of combustor zone increased by the temperature of preheated air increased, and the value of exhaust gas exergy have the same variation trend. This shows decrease the exergy loss of combustor zone can by increasee of preheated air, but this method is invalid during the period of improving the exergy loss of the head of furnace.