Study On Characteristics Of Particulate Matter In Gasifier And Gasification Slag Blending In The Preparation Of Coal-water Slurry

The high temperature particles inside the entrained-flow gasifier are middle products of the coal gasification reaction process,and its physical and chemical properties can be used as a reference factor for diagnosing the operation of the entrained-flow gasifier.Research on the change of particulate matter inside the entrained-flow gasifier and understanding the conversion process is of great significance for guiding the operation status of the gasifier.In this thesis,the particulate matter in the gasifier is taken as the research object.The physical and chemical properties of the particulate matter iniside the gasifier and the influence of the high temperature process on the particulate matter under different atmosphere are studied experimentally.Research on application of slag in preparation of coal-water slurry is also investigated.(1)The study on the physical properties of the particles inside the entrained-flow gasifier shows that the average particle size of the particles inside the gasifier increases first and then decreases along the axial position,and the coalescence and fragmentation of the particles appear in the gasifier simultaneously.The gasification reaction mainly happens at the height of 200 mm in the gasifier.The particles in the vicinity of this range have the highest reactivity.The instantaneous reaction rate of particulate matter inside the gasifier increases first and then decreases along the axial position.(2)The study on the change of the characteristics of the particles under different atmospheres in the high temperature process shows that the particles in different atmospheres will have different degrees of weight loss during the high temperature process.The loss of the particles in the CO2 atmosphere is greater than the weight loss in the N2 atmosphere.The high temperature thermal stress in the particles caused by high temperature is difficult to lead to particle fragmentation.The particle fragmentation is mainly caused by external force,and the high temperature process is beneficial to the expansion of the particles.At the same time,the pore structure trend of the particles in the high temperature process under the CO2 atmosphere is consistent with the change trend of the voids in the gasifier.(3)The study on the residual carbon residue distribution shows that the residual slag particles have the highest residual carbon content in the particle size range of 250-850?m.When different ash samples are mixed with Shenmu raw coal,the addition of fine slag causes an increase in apparent viscosity,and the addition of coarse slag causes a decrease in dispersion and stability.The effect of simultaneous mixing of fine slag and coarse slag is better than that of coal-water slurry prepared by mixing only with fine slag.The effect of simultaneous mixing of coarse and fine slag is closer to that of raw coal to prepare coal-water slurry.