Influence Of CaO-Fe₂O₃ On The Wetting And Corrosion Behaviour Of Coal Ash

In industrial production,CaO and Fe₂O₃oxides are commonly used as additives to improve the melting characteristics of high melting point coal ashes.However,the improved melting characteristics of coal ash enhance the tarnishing and corrosion effect on the lining of the gasifier,accelerating the destruction of the lining material,which is one of the main problems leading to the existence of gasifiers that do not operate stably over long periods.To investigate the wetting and corrosion behavior of SW coal which is added CaO and Fe₂O₃for modification,we investigated coal ash on resistant materials and the interaction of CaO and Fe₂O₃in the two behaviors to provide theoretical guidance to practical production.We analyzed The microscopic morphology and elemental composition distribution of the cooled samples’wetting surface and corrosion interface to compare the differences in crystalline morphology between the wetting surface and the corrosion interface.The trends of crystalline composition transformation of modified SW coal ash were analyzed using the thermodynamic calculation software（Factsage 8.1）and compared with the actual crystalline composition measured by X-Ray Diffractometer（XRD）.The SEM-EDX data revealed the spreading pattern of slag and the permeation diffusion mechanism of each element.The equation CaO and Fe₂O₃-temperature-contact-angle and the equations of CaO and Fe₂O₃-diffusion parameters constructed based on the experimental results.The results show:（1）when the CaO content of modified SW coal ash increases above 30%,melt-resistant minerals such as calcium-aluminum gehlenite and diopside appear,the crystal size becomes more prominent and the structure dense,and the final temperature contact angle increases;the Fe₂O₃content of modified SW coal ash increases above 50%leads to the increase of the initial temperature of wetting and the final temperature contact angle;as the regulation effect of CaO on the wetting angle is greater than that of Fe₂O₃,when the total amount of CaO and Fe₂O₃of modified SW coal ash is 50%,and CaO/Fe₂O₃is 4.0,the delamination wetting phenomenon occurs.（2）An increase in CaO content of modified SW coal ash above 40%can lead to the formation of CA_xat the slag plate interface,preventing corrosion behavior from proceeding;whereas Fe₂O₃content enhances the penetration of coal ash,Fe settles at the bottom of the slag,and forms a reaction layer.However,when the Fe₂O₃content of modified SW coal ash is increased above 40%,Fe₂O₃forms crystals on the slag surface,and settling and penetration are reduced.After reducing the total amount of Fe₂O₃and CaO of modified SW coal ash,the slag plate interface forms a double reaction layer and whether a continuous boundary can be formed on the substrate side determines the dominant behavior of corrosion.（3）The contact angle equations constructed by applying Boltzman and optimal surfaces in conjunction have a high correlation with the actual data,but some of the parameter equation surfaces are entirely distorted due to the limitations of the Boltzman base equation.In contrast,the constant diffusion equation constructed directly using the optimal surface is larger than the actual value because it does not consider the spinel-resistant slag layer’s permeation behavior and the effect.Also,the effect of the addition of CaO and Fe₂O₃for SW coal ash on the corrosion behavior is more complex and leads to deviations in the diffusion constants.Figure[60]Table[13]Reference[108]...