| Coal chemical wastewater is a kind of high-concentration industrial wastewater with large discharge,complex composition and strong toxicity,which brings great harm to human health and ecological environment,and also becomes a bottleneck restricting the development of the coal chemical industry.Collaborative treatment of coal chemical wastewater using coal water slurry technology to achieve zero discharge and harmless utilization of coal chemical wastewater has become a research hotspot in recent years.In this paper,the influence of coal chemical wastewater on coal water slurry gasification characteristics and slag characteristics is studied.Numerical simulation calculations of actual industrial wastewater coal slurry gasification furnaces are conducted.The research results have guiding significance for coal chemical wastewater treatment.A variety of coal chemical wastewater was mixed with pulverized coal to prepare coal water slurry,and the composition of the gasified synthesis gas was calculated by Fact Sage software,and compared with the results of ordinary clean coal water gasification.Coal chemical wastewater is rich in various organic substances and serves as a good gasification raw material during the gasification process.Under the same conditions,the effective gas(CO + H2)ratio of wastewater coal slurry has increased compared to clean coal water slurry.This shows that the addition of wastewater improves the target gas yield and is beneficial to reducing the cost of gas purification in the later stage.Coal slurry concentration and oxygen-to-coal ratio are two important factors affecting the gasification of coal water slurry.With the increase of the two,the temperature of the gasifier will increase,but the effective gas ratio will rise and fall respectively.The simulation results are compared with the actual values.The simulation results of the gasification process are in good agreement with the actual working conditions.Clean water(CL),carbonized water(TH),external wastewater(WL),scrubbing water(XQ),and sulfur water(LH)were selected to burn coal water slurry slag after pulverized coal,and the differences in melting characteristics of each slag were explored.The flowing temperature ranges from small to large,including clean water,external wastewater,scrubbing water,carbonized water,and sulfur water,but the overall change range is small.The addition of coal chemical wastewater caused more low-melting alkali metal oxides and high-melting Al2O3 to be formed in the slag.The interaction between the two did not change the oxide acid-base ratio in the slag composition.The viscosity-temperature characteristics of clean water,scrubbing water,carbonized water,external wastewater,and mixed wastewater coal slurry slag from the plant were investigated.The addition of coal chemical wastewater has changed the mineral composition of coal water slurry at high temperature.During the gasification process,more lowmelting minerals were generated,which reduced the solid phase content and species at high temperature,and the lower the high temperature viscosity of slag.The slag of actual industrial furnaces have a slight increase in high-temperature viscosity due to the combustion mode,the degree of combustion,and the instability of the working conditions,which does not affect the liquid slag discharge of the gasification furnace.In order to explore the specific temperature field and gas concentration distribution in the actual industrial furnace,and provide a basis for engineering practice,the Fluent software was used to study the gasification of coal water slurry,and the temperature field and concentration distribution of various gases in the gasification furnace were reproduced.To obtain the composition of the exit gas and the temperature in the furnace;the increase in the concentration of the coal slurry and the decrease in the ratio of oxygen to coal are beneficial to the increase in the proportion of the effective components in the exit gas,but at the same time the problems of the rise and decrease of the furnace temperature caused by the two are intolerable If neglected,it is easy to cause high temperature corrosion and liquid slag discharge accidents on the wall of the gasifier. |
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