THE EFFECT OF A THIN CR₃C₂-NICR HVOF COATING ON THE THERMAL RESISTANCE AND TEMPERATURE DISTRIBUTION OF STEAM SUPERHEATER TUBES IN A BKZ-320-140 BOILER

This study analyzes the effect of HVOF-sprayed Cr₃C₂-NiCr coatings on the thermophysical characteristics of superheater tubes of the BKZ-320-140 boiler unit. The influence of the protective coating on heat transfer processes, including convective and radiative heat exchange, as well as on the temperature state of the tube material under high-temperature flue gas conditions, is investigated. The temperature field was calculated using the finite element method in the ELCUT 6.6 software under transient heat transfer conditions. The model incorporates real operating parameters, including steam pressure and temperature, flow velocities, and thermophysical properties of materials. The results show that the presence of the coating leads to a slight increase in the total thermal resistance of the “tube wall–coating” system. However, its effect on the temperature regime and heat flux density is negligible. It is demonstrated that Cr₃C₂-NiCr coatings improve the corrosion and erosion resistance of heating surfaces without significantly reducing the thermal efficiency of the boiler unit under real operating conditions. The obtained results can be applied in design, modernization and optimization of power equipment in industrial energy systems of Kazakhstan.

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