【Q&A Question 094】2016.07.23
Thread Content
【Q&A Question 094】July 23, 2016: What is the impact of the oxygen content in flue gas on the efficiency of heating furnaces? The answer key will be available after responding; scoring is based on answering the key points. 1. When the oxygen content in the flue gas is too high, the air entering the furnace carries away a large amount of heat, resulting in a decrease in thermal efficiency ； 2. When the oxygen content in the flue gas is too low, the gas does not burn completely; heat remains in the furnace, which reduces the efficiency of the heater.
A low oxygen content can lead to incomplete combustion, reducing the efficiency of the heating furnace； However, a high oxygen content will take away some of the heat generated during combustion, thereby reducing the efficiency of the heating furnace as well. A reasonable value should be set for the oxygen content.
High oxygen content reduces furnace efficiency
When the oxygen content in the flue gas is too high, the air entering the furnace carries away a large amount of heat, resulting in a decrease in thermal efficiency； When the oxygen content in the flue gas is too low, the gas does not burn completely; heat remains trapped in the furnace, resulting in a reduced efficiency of the heating furnace.
Excessively high oxygen content, large excess air coefficient, resulting in low efficiency of the heating furnace； If the oxygen content is too low, combustion is incomplete, and the efficiency of the heating furnace is also low. The controlled oxygen content in the gas fuel is 1-3% ； It is better to keep the control of fuel-based fuel at 3-5%.
The higher the oxygen content, the lower the thermal efficiency.
A high oxygen content in the flue gas leads to an increased amount of air entering the furnace, which lowers the furnace temperature and affects heat transfer. At the same time, an increased volume of flue gas results in more heat being carried away. If the oxygen content in the flue gas is too low, the fuel does not burn completely, leading to waste of fuel. Therefore, it is advisable to keep the oxygen content in the flue gas at around 2%-3%.
The oxygen content is inversely proportional to thermal efficiency; in other words, a high oxygen content results in low thermal efficiency, while a low oxygen content leads to high thermal efficiency!
Too high a value reduces the furnace’s thermal efficiency, and it also accelerates the oxidation of the furnace tubes. Too low a value leads to incomplete combustion, which likewise reduces the furnace’s thermal efficiency
A high oxygen content means more air, which carries more heat, thereby reducing the efficiency of the heating furnace
A high oxygen content in the flue gas leads to an increased amount of air entering the furnace, which lowers the furnace temperature and affects heat transfer. At the same time, an increased volume of flue gas results in more heat being carried away, reducing the efficiency of the heating furnace. A low oxygen content in the flue gas causes incomplete combustion of the fuel, thereby also reducing the efficiency of the heating furnace.