Study Of Composite Ceramic Coating Characteristics For Protecting Heating Surface And Improving Heat Transfer Performance

Based on the high-temperature corrosion problem,a kind of composite ceramic coating were prepared on the surface of steel by thermal chemical reaction,and it was tested by the thermal shock performance,high-temperature oxidation resistance property,high-temperature corrosion resistance property,emissivity and thermal conductivity.For the decline of heat-transfer performance caused by slagging,the influence of coating prepared at different area of boiler on heat-transfer performance were simulated by fluent,and research the best area for preparing coating.First,ceramic coatings were prepared on 5 normal steels(20G,12Cr1 Mo VG,15 Cr Mo G,T91,TP347)for boiler.The microstructure,phase composition,and phase structure were research by SEM,EDS.Then test thermal shock performance,high-temperature oxidation resistance property emissivity and thermal conductivity of coatings.The result showed that the coatings had excellent thermal shock resistance,and thermal shock resistance linear decrease with the increase of coating thickness.Compared with steel samples,coating samples had a lot of promotion of high-temperature oxidation resistance.Emissivity of coatings reached 0.9,thermal conductivity of coating sample is closed to steel sample.Then,coatings were prepared on water wall and platen superheater.But the main steam at a subnormal temperature during the actual operation.In order to solve the problem,using Fluent to simulate the boiler.The research showed that the heat absorption capacity of water wall increased dramatically after prepared coatings and the heat absorption capacity of superheater decreased lead to the problem of the main steam at a subnormal temperature.simulation results of preparing coatings at different areas of water wall and superheater showed that increase areas on superheater can improve its heat-transfer performance,so steam temperature can be kept,and flue gas temperature after furnace can be reduced.Besides,the working conditions of changing furnace flame center height based on the condition of preparing coatings on whole-wall superheater also be simulated.