In most cases, the superheater of high pressure industrial gas steam boiler is mainly convective heat transfer. We all know that the steam temperature of countercurrent superheater decreases with the decrease of load. When the load of industrial gas steam boiler is low, it is possible to shut down the desuperation water regulating valve completely and the steam temperature is still below the lower limit. Although it is possible to increase the steam temperature by increasing the excess air coefficient at the furnace outlet or the negative pressure in the furnace of industrial gas steam boiler, these methods increase the excess air coefficient of smoke exhaust due to the increase of smoke exhaust temperature, resulting in an increase in the heat loss of smoke exhaust. It leads to the decrease of thermal efficiency of industrial gas steam boiler.
If the lower layer burners are stopped as far as possible and the upper burners are used more often, the furnace heat absorption will decrease and the smoke temperature at the furnace outlet will rise due to the upward movement of the furnace flame center. Due to the increase of radiation heat absorption and heat transfer temperature difference, the total heat absorption of superheater increases, which makes the steam temperature rise. This method of regulating steam temperature is more economical, and it is the first method to be adopted when the steam temperature is low due to low load.
