The relationship and differences between the oxygen content in the furnace chamber and that in the flue gas in a heating furnace
Thread Content
The relationship and differences between the oxygen content in the furnace chamber and that in the flue gas in a heating furnace
The oxygen content in the furnace chamber of a heating furnace is actually roughly the same as that in the flue gas. It depends on the design of the furnace; theoretically, the oxygen content in the flue gas should be higher than that in the furnace chamber. The difference in oxygen content is due to the oxygen that leaks in around the furnace after combustion (some of this leakage occurs intentionally, such as through the cooling air used in flame monitoring systems)； There are cases of passive leakage, such as leaks in the furnace walls
Theoretically, the oxygen content in the furnace chamber of a heating furnace is roughly the same as that in the flue gas. In practice, however, the oxygen content in the flue gas is slightly higher than that in the furnace chamber; this difference becomes even greater when there are leaks in the furnace walls or when the negative pressure in the furnace chamber is high.
Regarding the issue raised by the original poster, the relationship between the two is explained as follows for reference. 1. Strictly speaking, given a fixed amount of fuel fed into the heating furnace, the higher the oxygen content in the furnace chamber, the higher the oxygen content in the flue gases as well ； Conversely, the oxygen content in the flue gas is lower. 2. To ensure the thermal efficiency of the heating furnace, the oxygen content in the furnace chamber must be controlled appropriately. If it is too low, incomplete fuel combustion may occur, leading to fuel loss and waste ； If it is too high, it indicates that an excessive amount of air has been added. With a constant amount of fuel, the amount of oxygen required also remains constant; the excess oxygen (which, if it is air, also contains a large amount of nitrogen) must be emitted as flue gas, carrying away some heat and thus causing heat loss. Therefore, to control an appropriate air excess factor, it is sufficient to ensure that the fuel burns completely.