The purpose of the fan
G4-73 and Y4-73 boiler ventilation and induced draft fans are mainly suitable for the ventilation and induced draft systems of 2-670t/h steam boilers in thermal power plants. G4-73 can also be used for mine ventilation and general ventilation unless otherwise specified.
The medium conveyed by the ventilation fan is air, and the maximum temperature shall not exceed 80 ℃; The medium conveyed by the induced draft fan is flue gas, and the maximum temperature shall not exceed 250 ℃.
Before the induced draft fan, a dust removal device must be installed to minimize the dust content of the flue gas entering the fan as much as possible. According to the usage of general power plants, the efficiency of the equipped dust collector shall not be lower than 85%.

Type of fan
1. The ventilation fan and induced draft fan are both made into single suction units, with 13 unit numbers ranging from No. 8-29.5 each.
2. From one end of the motor, if the impeller rotates clockwise, it is called a right cyclone machine, represented by "right"; On the contrary, it is the left cyclone machine, represented by "left".
3. The position of the air outlet of the fan is represented by the angle of the air outlet of the casing.
4. The transmission mode of the fan is D-type, all of which are connected by elastic couplings.

The structure of the fan
The fan is mainly composed of an impeller, a casing, an air inlet, a regulating door, and a transmission part.
1. Impeller -12 angled angled blades are welded between the conical front plate and the flat rear plate. Due to the use of wing shaped blades, the main efficiency, low noise, and high intensity of the fan are ensured. The impeller has undergone static and dynamic balance correction and overspeed operation test, so it runs smoothly and reliably. The impellers of ventilation fans and induced draft fans with the same machine number have the same structure but different materials. Generally, A3 is selected for ventilation fans and 16Mn is selected for induced draft fans.
2. Shell - welded into a snail shape with ordinary steel plates. The casing of the single suction fan is made in three different forms (the casing of No. 8-12 is made as a whole structure and cannot be disassembled, the casing of No. 14-16 is made as a two open type, and the casing of No. 18-29.5 is made as a three open type). The volute plate of the induced draft fan has been appropriately thickened to prevent wear and tear.
3. Air inlet - The convergent and streamlined air inlet is made into a whole structure and fixed to the inlet side of the fan with bolts.

4. Regulating door - a device used to regulate flow, installed axially before the air inlet. The adjustment range is from 0 degrees (fully open) to 90 degrees (fully closed). Position of the handle for adjusting the door: viewed from the air inlet direction on the right side, for the right cyclone machine, pushing the handle from bottom to top is in the fully closed to fully open direction, and for the left cyclone machine, pulling the handle from top to bottom is in the fully closed to fully open direction.

5. Transmission - The main shaft of the transmission part is made of high-quality steel, and this fan uses rolling bearings. There are two forms of bearing boxes: Type 8-16 uses integral cylindrical bearing boxes; Use two independent pillow type bearing housings for No. 18-29.5. The bearing box is equipped with a thermometer and an oil level indicator (only for the induced draft fan). Lubricating oil adopts No.30 mechanical oil, and the amount of oil added shall be in accordance with the oil level indication requirements. If dry oil is used for the integral cylindrical bearing box of No. 8-16, an oil baffle should be added on one side of the ball in the bearing box, and its fixing groove should be made. The induced draft fan is equipped with a water cooling device, therefore, a water supply pipe must be added, and the water consumption varies with the temperature, generally considered at 0.5-1m3/h.