The combustion air preheater is definitely one of heat exchanger applications. Based on Figure 1 below, flue gas simply leaves steam boiler and passes via air preheater. The combustion air is passed through this equipment too to increase its temperature before being combined with boiler fuel.
Because the temperature of combustion air is lower than the temperature of flue gas, combustion air receive heat transfer from flue gas through combustion air preheater in the process of convection heat transfer. The heat transfer make temperature of flue gas lower and consequently minimizes its heat loss and also decreases the air temperature to stack.
The service life of your industrial boiler is 15 years. Of course, there are a number of factors that may force you to replace your boiler before it reaches the 15-year mark. If there are obvious signs of wear and tear, you may not want to push the boiler much longer.
In superheated industrial water boilers, the water is pressurized and boiled to 100°C producing steam. These boilers are pyrotubular, with a high volume of water and a large temperature exchange zone. The designs can adapt to temperatures and pressures according to needs.
