| Coal slime and coal gangue are generally produced during coal mining and washing.A large amount of these by-products will cause waste of resources and environmental pollution.Both coal gangue and slime have a certain calorific value,so power generation through boiler combustion is a common method for comprehensive utilization of two inferior fuels.At the same time,most of the coal gangue contains more free calcium base,which theoretically has a certain inhibitory effect on the sulfur emission in the mixed fuel.Circulating fluidized bed(CFB)boilers have good coal type adaptability and are an important means to eliminate inferior fuels such as coal slime and coal gangue.To this end,the state has proposed a key research and development project of "Super Supercritical Circulating Fluidized Bed Boiler.Technology R&D and Demonstration"which is proposed to carry out engineering demonstrations of mixed fuels of coal gangue?coal slurry and terminal coal through ultra-supercritical circulating fluidized bed.This requires relevant combustion mechanism and pollutant control research to provide theoretical support for new fluidized bed design.In this paper,thermal analysis is used to study the combustion of coal gangue and mixed fuel.The research shows that the weight loss process of burning coal slime and terminal coal can be divided into two stages:the first stage is the water evaporation and water loss drying stage;the second stage is the combustible combustion stage,and the weight loss process of burning coal gangue can be divided into three stages:the first two stages are similar to the slime,and the third stage occurs at 650??800?.mainly caused by the decomposition of CaCO3;after the addition of coal gangue.due to the increase of ash content of the mixed fuel,the ignition temperature of the sample is shifted backward,The combustion intensity and the steady combustion characteristics are reduced,and the change in burnout temperature is not the same;after adding coal gangue,the proportion of ash in the mixed fuel increases,which will cause the sample to generally increase the activation energy and decrease the pre-exponential factor.In this paper,the fixed bed method is used to study the combustion of coal gangue and mixed fuel,and the total amount of sulfur in the ash and flue gas is tested by desorption method and solution absorption method respectively.The results show that under certain working conditions,the self-desulfurization efficiency of coal gangue can be as high as 71.99%.After adding coal gangue,the desulfurization efficiency of mixed fuel will generally increase by 2 to 3 times,the best desulfurization effect of mixed fuel at 800? and 900? and the temperature above is consistent with the furnace outlet temperature of the CFB boiler.When the sample was characterized by SEM-EDS,it was found that CaO in coal gangue clogged after absorbing SO2 and SO3 in the flue gas,and small particles on the surface of the particle were protruded. |
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