Heat Exchange and Hydrodynamic Characteristics of Unified Package of Cold Layer of RAH

Abstract

Heating the air in the boiler air heater with the heat of fuel combustion products performs the functions of increasing the fuel combustion temperature, increasing the temperature level of gases in convective heating surfaces, improving ignition and fuel combustion conditions, increasing boiler efficiency by utilizing waste gas heat, improving fuel quality due to its preliminary supply, etc. However, the peculiarities of the process of heating the air in the air heaters do not allow to achieve a decrease in the temperature of the exhaust gases. This is due to the unfavorable ratio of heat capacities of flue gases and air, as well as corrosion and contamination of the heating surfaces of air heaters. The research of heat transfer processes and hydraulic resistance of unified package of cold layer of RAH is depicted at this work. The graphic dependence of the change in the coefficient of hydraulic resistance and Nu number for unified packages with single line of sheets and simplified profile with corrosion resistance enamel from the Reynolds number for different values of the length of the replaced areas was constructed. The unified packing of the simplified profile has increased by 1.17 times equivalent diameter and is characterized by good operational parameters and takes into account the risk of contamination of heating surfaces due to the enamel coating.