The Influence Of Coal Blending And Return Ash Content On Operation Of The CFB Boiler

In recent years, waste production such as household waste and industrial waste increase rapidly among many cities in China, which confront garbage siege along with the high-speed economic development and urbanization process. Incineration has been widely developed and applied in China for its advantages of harmless, reduction and recycling to deal with household waste. CFB is a highly effective and less-polluting combustion technology which is characterized as wide fuel adaptability, flexible load regulation, lower NO_x emission and high efficiency in recent decades.A simulation system is established based on a domestic 12 MW CFB incinerator utilizing Aspen Plus platform, which calculates and analyzes variations of operating parameters of the boiler under different quantities of blending coal. Several methods are taken to analyze the change of CFB incinerator with returned ash content including changing choices of reasonable mixed combustion ratio, selecting quantities of blending coal.The results show that the boiler evaporation volume, the boiler heat efficiency decreases, temperature of the flue gas increases, the volume concentrations of SO₂, SO₃, NO_x in flue gas of the furnace outlet and the carbon content of the fly ash decrease, while the volume concentration of Cl₂ and HCl in smoke increases. When we maintain quantity of blending coal unchanged and change returned ash content, it’s found that the temperature of CFB incineration increases with returned ash content growth and the emission concentration of NOx in flue gas at the exit of furnace firstly increases gradually and tend to be gentle after that. Besides, emission concentration of Cl₂ discharge concentration gradually decreases, while this trend is not obvious. At last, the emission concentration of SO₂ and HCl remain unchanged basically.Eventually, we study on practical application of CFB boiler which is tested by operating method and the influence of the amount of waste and returned ash content on the operation performance of CFB incineration. Conclusion is firstly that fluidized bed model is reasonable. Secondly, CFB incineration model has practical significance to some extent. Simulation data can be used as the base of actual CFB incineration operation and adjustment in a certain extent.