Application
G4-73 and Y4-73 boiler induced draft fans are suitable for induced draft fan systems of steam boilers below 670V/h in thermal power plants. G4-73 can also be used for mine ventilation and general ventilation when there are no other special requirements. The medium conveyed by the ventilator is air, and the maximum temperature shall not exceed 80°C; the medium conveyed by the induced draft fan is flue gas, and the maximum temperature shall not exceed 250°C. A dust removal device must be installed in front of the induced draft fan to minimize the dust content of the flue gas entering the fan. According to the general use of power plants, the dust removal efficiency shall not be less than 85%.
Type
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1. The ventilator and induced draft machine are single suction, with 12 machine numbers from No.8 to No.28.
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2. When viewed from the motor end, if the impeller rotates clockwise, it is called a right-hand cyclone fan, represented by "right"; if the impeller rotates counterclockwise, it is called a left-hand cyclone fan, represented by "left".
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3. The air outlet position of the fan is expressed as the air outlet angle of the casing.
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4. The fan transmission mode is D type, and elastic coupling is used for transmission.
Structural characteristics
The fan is mainly composed of an impeller, a casing, an air inlet, an adjusting door, and a transmission part.
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1. The impeller consists of 12 backward-inclined wing-shaped oblique blades welded between the conical front disc and the flat rear disc. The use of wing-shaped blades ensures high efficiency, low noise, and high strength of the fan. The impeller is calibrated for static and dynamic balance, so it runs smoothly. The impeller structure of the induced draft fan and the induced draft fan of the same machine number is the same.
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2. The casing is a volute body welded from ordinary steel plates. The casing of the single-suction large fan is made into three different forms: No. 8~12 casings are made into an integral structure and cannot be disassembled; No. 14-No. 16 casings are made into two-opening type; No. 18-No. 28 casings are made into three-opening type. The induced draft fan and volute plate are appropriately thickened to prevent wear.
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3. The convergent and streamlined air inlet is made into an integral structure and fixed to the inlet side of the fan with bolts.
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4. The regulating door is a device used to adjust the fan flow rate. It is installed axially in front of the air inlet. The adjustment range is from 0° (fully open) to 90° (fully closed). The lever position of the regulating door is on the right side when viewed from the air inlet. For a right-handed fan, pushing the lever from bottom to top is from fully closed to fully open; for a left-handed fan, pulling the lever from top to bottom is from fully closed to fully open.
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5. The main shaft of the transmission part is made of high-quality steel and is supported by rolling bearings. There are two types of bearing boxes: No.8No.16 use an integral simple bearing box; No.18No.28 use two independent pillow bearing boxes. The bearing box is equipped with a thermometer and an oil level indicator (only for induced draft fans). The lubricating oil uses the full-loss system oil L - AN46, and the amount of oil added is in accordance with the requirements of the oil level mark. If grease is used for the integral simple bearing box of No.8-No.16, an oil baffle plate should be added on the side of the ball in the bearing box, and its fixing groove has been prefabricated. The induced draft fan is equipped with a water cooling device, so a water pipe must be installed. The water consumption varies with the temperature and is generally considered to be 0.5~1 m³/h.
Performance and selection
For G4-73 and Y4-73 fans, only the performance table and performance curve of dimension 1 of the No.10 model are given. Based on the performance table or performance curve of dimension 1, the dimensioned performance of all models No.8~No.28 can be calculated. For the treatment of excessive or insufficient flow during fan use and new installation and operation, refer to the Y4-70 centrifugal induced draft fan.
