Air pre-heater is a kind of equipment used to improve the heat exchange performance of the boiler and reduce energy consumption. Air preheater is generally divided into three types: plate type, rotary type and tube type. Taking rotary type as an example, the working principle of air preheater is introduced. A large number of unburned combustibles will deposit on the heat transfer elements, which may cause the air preheater to ignite. The reasons for the ignition and the countermeasures are described in detail. The analysis of the switch-off and the treatment of air leakage are also introduced in detail.
The function of air preheater
1. improve and intensify combustion
The air after the heat exchanger enters the furnace, which accelerates the drying, ignition and combustion process of the fuel, ensures the stable combustion in the boiler and improves the combustion efficiency.
2. heat transfer enhancement
Because the combustion in the furnace has been improved and strengthened, and the temperature of hot air entering the furnace has been increased, the average temperature level in the furnace has also been raised, so the radiation heat transfer in the furnace can be strengthened.
3. reduce furnace loss, reduce exhaust gas temperature and improve boiler thermal efficiency.
Because of the stable combustion in the furnace and the enhanced radiation heat exchange, the chemical incomplete combustion loss can be reduced. On the other hand, the waste heat of flue gas is utilized by the air preheater, which further reduces the loss of exhaust gas, thus improving the thermal efficiency of the boiler. According to experience, when the air in the preheater rises by 1.5 C, the exhaust gas temperature can be reduced by 1 C. After installing the air preheater in the boiler flue, if the air waste heat can be 150-160 C, the exhaust gas temperature can be reduced by 110-120 C, and the thermal efficiency of the boiler can be increased by 7%-7.5%. It can save fuel 11%-12%.
4. hot air can be used as fuel desiccant.
Hot air is an important desiccant and pulverized coal conveying medium for grease powder system in power plant boilers.
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