What percentage of the total heat transfer area of a boiler do the economizer and air heater sections account for?

The economizer and air heater sections of a boiler play a crucial role in enhancing the overall thermal efficiency by recovering waste heat from the flue gases. These components are designed to preheat the feedwater and the combustion air, respectively, which reduces the energy needed from the fuel during the combustion process.

Typically, the economizer and air heater combined can account for approximately 75% of the total heat transfer area within a boiler system. This significant percentage highlights their importance in maximizing energy recovery and minimizing fuel consumption. By increasing the surface area designated for heat transfer in these specific sections, the boiler can operate more efficiently, leading to improved performance and reduced operational costs.

In a well-designed system, these components are optimized to utilize as much of the available heat from the exhaust gases as possible, justifying the considerable portion of the total heat transfer area they represent. Thus, recognizing that they account for 75% emphasizes the critical part they play in overall boiler efficiency and heat recovery.