Study On Formation And Deposition Characteristics Of Initial Coal Ash Deposit In Zhundong

As the basic energy,coal still occupies the main part of energy in a short time.The higher alkali metal in Zhun dong coal affects the practical application of this good power coal.When burning Zhun dong coal,it is easy to form the initial deposit layer with high viscosity,which aggravates the contamination and corrosion of heating surface.Therefore,it is of great significance to explore the formation of initial deposition layer and its influence on ash deposition characteristics in the process of burning Zhun dong coal.Taking Wu cai wan Zhun dong coal as the research object,the effects of probe temperature and combustion temperature on the initial deposition layer of Zhun dong coal were investigated on the evaporation condensation test bench.The morphology and quality change of the condensate on the probe surface were investigated macroscopically.The phase,microstructure and chemical composition of the condensate were investigated by XRD and SEM-EDS.The influence of probe temperature on ash deposition in Zhun dong was studied by one-dimensional combustion deposition test-bed.The ash deposition characteristics were characterized by ash deposition height curve and ash deposition rate.XRD and SEM-EDS were used to characterize the phase,morphology and chemical composition of the ash.Firstly,the evaporation condensation test-bed is built and the original fly ash deposition test-bed is modified.A plane flame burner was added to the original fly ash deposition test-bed to increase the reaction temperature,and the original cross quartz tube was redesigned to ensure the stability of the test-bed.Secondly,the condensation characteristics of alkali metals during combustion at different probe temperatures were studied.Na in Zhun dong coal is mainly released into the flue gas in the form of Na Cl molecules and condensed on the low temperature probe to form crystals.SO₂in the flue gas will react with Na Cl in heterogeneous sulfation,and the by-product Cl will corrode the surface of the probe.Reducing the heating surface temperature and combustion temperature will inhibit the reaction.Then,the influence of probe temperature on ash deposition characteristics of Zhun dong coal during actual combustion was studied.The deposition process of Zhun dong coal ash can be divided into three stages:formation stage,growth stage,highly stable stage and stable growth stage.Zhun dong coal ash has obvious layered structure.The inner layer is mainly composed of alkali metal and alkaline earth metal sulfate with high viscosity,and the middle and outer layers are sintered.The increase of probe temperature can increase the ash deposition quality and height by increasing the viscosity of the initial deposit.At the same time,the sintering degree of the ash can be increased to further change the density of the ash,so as to improve the ash deposition quality.