Study On Mixing Combustion Characteristics Of Raw Coal With Gasification Fine Slag

Coal gasification process will produce a large number of gasification fine slag,but the utilization rate is very low.Most of gasification waste slags are directly landfilled,not only waste land resources,but also pollute the water and atmosphere.In this study,TG-MS was used to determine the residual carbon content of gasification waste residue.It was found that the loss of coarse slag was low and could be directly utilized,while the fine slag had high carbon content and poor ignition characteristics,which made it difficult to recycle and utilize.Blending fuel coal is an effective method to solve ignition difficulty and poor burnout of low-volatile gasification fine slag.The characteristics of separate combustion of gasification fine slag and mixed combustion of coal with power feedstock were studied by thermogravimetry,the influence of mixing ratio on mixed combustion was investigated,and the interaction and reaction kinetics of mixed combustion were analyzed The main findings are as follows:1.The residual carbon content of gasification waste residue was determined by three different methods(traditional loss of combustion method,single atmosphere method and double atmosphere method).As the ash and slag discharged from the circulating fluidized bed boiler are different from that of pulverized coal furnace,part of its mass loss is caused by water evaporation,so the traditional loss cannot replace the determination of carbon content.The double atmosphere method can accurately measure the residual carbon content.2.Thermogravimetric analysis experiments on gasification fine slag mixed with 0%,10%,30%,60%and 100%in coal samples,and investigated the influence of mixture ratio on ignition point,burnout point,maximum combustion rate and comprehensive combustion characteristic index of sample combustion.The result show that there is a significant synergistic effect between gasification fine slag and blending of raw coal.The higher proportion of mixed raw coal,the better flammability and comprehensive combustion characteristics.3.Thermogravimetric experiments were conducted at different heating rates,with heating rates of 10?/min,150C/min,20?/min,respectively.The kinetics of combustion reactions under different heating rates were analyzed.It was determined that the reaction order of coal and gasification fine slag was 1,and the optimal combustion rate was 10?/min.It is concluded that the larger mixing proportion of gasification fine slag,the larger activation energy of mixed combustion,and the more difficult of reaction.Through this study,it can be found that it is feasible to mix gasification fine slag with coal,which is of practical significance to improve the combustion characteristics of gasification fine slag,effectively utilize the calorific value of gasification fine slag,and solve the problem of solid waste disposal.