What are the factors that cause excessive temperature of the induced draft fan

Update:24-05-2021
Summary:

The ambient temperature is the temperature in the fan r […]

The ambient temperature is the temperature in the fan room. Since the cooling fan that cools the bearing box of the induced draft fan transports the air in the suction fan room, the indoor temperature has a great influence on the temperature of the induced draft fan bearing.
The factors that affect the ambient temperature mainly include the following aspects.
1. Seasonal factors
Due to the geographical location of the region, the four seasons are very different. In winter, the temperature is minus 10-20℃. Although there is heating in the induced draft fan room, the highest temperature is only 19℃; and the highest temperature in summer reaches 38℃. The temperature is as high as 40℃, so under normal circumstances, the high temperature of the induced draft fan bearing only occurs in the summer high temperature season.


2. The influence of unit load and exhaust gas temperature on bearing temperature
The high-temperature flue gas is conveyed in the induced draft fan. Because the bearing box is arranged inside the casing, the high-temperature flue gas flows around the bearing box, so that heat exchange occurs to the bearing. Generally, the exhaust gas temperature of the boiler of a unit is 140~150℃, but the boiler has a maximum exhaust gas temperature of 175℃ due to the fact that the soot blower is not fully put in, the flue gas baffle is removed, the burner cannot be adjusted, and the furnace ash accumulation is serious. The heat transferred from the flue gas to the bearings is relatively large, so the bearing temperature of the induced draft fan of the boiler is about 15°C higher than that of other units.

3.The influence of the structure of the induced draft fan chamber and the thermal insulation effect of the fan body on the ambient temperature
The induced draft fan room of the first-phase unit has poor ventilation effect and high ambient temperature due to the modification of the electric dust removal structure and other reasons. Therefore, the bearing temperature of the first-stage induced draft fan is generally higher than that of the second-stage induced draft fan. In addition, because the induced draft fan transports high-temperature flue gas, the fan itself is also dissipating heat outward, so the heat preservation effect of the fan is also an important factor determining the ambient temperature. The main solution is to install mechanical ventilation equipment in the induced draft fan room with poor ventilation effect to force circulation. In addition, improve the heat preservation of the machine body and choose materials with high heat preservation performance. These can all play a positive role in reducing the ambient temperature.
4. Motor heat dissipation factors
The heat dissipation temperature of the motor has a great influence on the ambient temperature. The heat dissipation temperature of the motor has a certain relationship with the power and structure of the motor. In addition, the part of the stator coil of the motor is opened and the motor is not tightly sealed, which will also cause the heat dissipation temperature to be high.

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