For boilers with a four-layer secondary air system, how can the exhaust gas temperature be reduced?

The last edit to this post was made by zgj2405 on 2011-10-21 at 14:28. Reply 1# zgj2405: First of all, the opening degree of the two fans is not determined by the exhaust gas temperature; it is determined by the air excess factor. It is the amount of air required for fuel combustion that determines the total air flow. To be honest, I didn’t understand what you meant by ‘up and down, down and up’ – it’s probably referring to the distribution of the secondary air vents. It’s also unclear whether your primary air and secondary air are arranged in a centralized manner or in a distributed manner. Personally, I feel that your setup seems to work like a combustion with varying intensity; it’s more like a setup designed to reduce Nox levels. Generally speaking, the use of vertical concentration technology can reduce Nox levels and somewhat decrease flue gas losses; however, the carbon content in the fly ash may increase. The opening degree of the secondary air is related to the amount of primary air supplied to the nozzles. Oxygen-deficient combustion must be employed in the main combustion zone in order to suppress the formation of thermally generated Nox. An air excess factor of OFA greater than 1 ensures complete combustion. So I think there might be something wrong with your starting point. I think to reduce the flue gas temperature, one can take the following approaches: First, control the temperature at the furnace outlet so that it isn’t too high; this can be achieved by removing coke deposits and ash buildup from the water wall and superheater, as well as by controlling the residence time of fuel in the furnace. Additionally, improving the heat exchange capacity of the air preheater and economizer will also help to lower the flue gas temperature. These are my personal opinions; please feel free to correct me.