The main unit and auxiliary components of the main ventilation fan

1) The complete components of the fan include tunnel joints, inlet collectors, primary-stage fans, secondary-stage fans, diffusers, round-to-square transitions, silencers, diffusion towers, and more. The internal flow passages of the fan are uniformly smooth. The inlet collectors, rectifiers, and fish-tail tubes are all manufactured using cold-roll forming with molds. To ensure uniformity and smoothness of the fan’s flow passages while minimizing flow resistance and enhancing fan performance, the fish-tail heat-dissipating tubes and motor base support plates adopt arc-shaped transitions and other drag-reducing measures, all while meeting stringent mechanical requirements for strength and rigidity. All types of supports feature symmetrical structural designs that optimize the internal flow passage configuration. The installation method involves arranging two fans side by side in a horizontal layout. Each fan is equipped, as standard, with pressure-measuring rings and other performance-testing interfaces for measuring parameters such as negative pressure and airflow rate; these interfaces can be connected to pressure sensors to measure both dynamic and static pressures as well as airflow rates. Vibration measurement mounts are installed on the outer wall of the duct, with预留 interfaces for mounting vibration sensors. The design and manufacturing of each fan component must ensure that it can withstand the required strength under various operating conditions. The hub material shall be no lower than Q345, and its outer circle shall feature a spherical surface structure. The thickness of the hub spokes shall be no less than 35 mm. The fan casing material is Q235; the steel plate used for the main housing shall have a minimum thickness of 8 mm, while the steel plate for the motor base shall have a minimum thickness of 25 mm. The inner cylinder of the protective sleeve shall be machined and formed to a minimum thickness of 15 mm after processing. The design and manufacturing of all fan components must guarantee their ability to endure the required strength under various operating conditions. After welding, the entire hub undergoes annealing treatment. Major components such as the hub and blades must undergo non-destructive testing and provide inspection reports to ensure quality and reliability. The weld seams of the fan shall be neat, aesthetically pleasing, and free from any welding defects. All critical welded parts of the fan are subjected to heat treatment to eliminate residual stresses.

2) Processing and Anti-corrosion & Rust Removal of Fan Housing: The raw material used is high-quality Q235 steel, and a material certification report will be provided. The entire housing is cut using a laser cutting machine, ensuring high dimensional accuracy and efficiency, thereby better guaranteeing product quality. All welding operations employ CO2 shielded arc welding technology to minimize deformation of the fan housing, ensuring that all housings meet the design specifications. After welding and forming, the housings undergo sandblasting treatment, leaving the steel surface free of any visible residues such as oil, dirt, oxide scale, rust, or paint coatings, thus enhancing the adhesion of both primer and topcoat. The primer is applied in two coats; prior to shipment, the fan is further coated with a protective polyurethane topcoat once. Each primer coat has a film thickness of 30–40 μm, and the final topcoat applied at the time of shipment results in a total coating thickness of 100–140 μm. The exterior color of the fan will be determined according to the customer’s requirements.

3) Noise Reduction Measures for Fans: The noise generated by fans primarily stems from motor operation noise, noise caused by airflow, and other mechanical noises. To address these noise sources, in addition to optimizing fan performance through the design of flow separation chambers, diffusers, specialized silencers, and diffusion towers, the fans are designed with low-noise features. The fans are equipped with silencer-diffusers (2-stage), in-line silencers, and built-in sound-absorbing panels within the diffusion towers as noise reduction measures. The fan noise levels comply with the provisions of JB/T 8690 “Noise Limits for Fans” and meet the requirements of environmental impact assessments. All silencer-diffusers are fitted with sound-absorbing layers, with a layer thickness of no less than 50 mm and perforated plates at least 3 mm thick, ensuring structural strength and incorporating corrosion-resistant treatments. The sound-absorbing cotton used has a bulk density of no less than 35 kg/m³. The in-line silencer features a square structure, with an axial length of 2 meters. Both the inner wall of the silencer casing and the built-in sound-absorbing panels are made of perforated sound-absorbing plates and filled with sound-absorbing cotton, which has a bulk density of no less than 35 kg/m³. The casing of the in-line silencer has a plate thickness of 6 mm, and the sound-absorbing layer within the casing is 80 mm thick. The in-line silencer contains nine sound-absorbing panels, each 150 mm thick, with individual panel dimensions of 1.8 m × 4 m. The diffusion tower is equipped with seven built-in sound-absorbing panels, whose lengths match the internal width of the diffusion tower, with a width of 1 meter each. Each sound-absorbing panel is 100 mm thick, and the bulk density of the sound-absorbing cotton within each sound-absorbing layer is no less than 35 kg/m³.

The sound-absorbing cotton is made from non-combustible or flame-retardant materials. Measures taken from three aspects— aerodynamic noise, motor noise, and mechanical noise—effectively reduce the operating noise of the fan. The noise level complies with the requirements of B/T8690-2014, "Industrial Ventilation Fans—Noise Limits."

4) Drainage of the fan: A drainage slope is provided at the bottom of the fan housing, and drain holes and drain valves are installed at the lowest points of each component. Additionally, heating cables are evenly wrapped around the drainage pipeline to ensure that the pipeline does not freeze even when temperatures reach their lowest point in winter in this region. The electric heating and insulation facilities are equipped with explosion-proof devices.

5) Impeller Cylinder Protective Ring: A copper ring is installed between the blades and the casing to prevent metal-to-metal contact and subsequent spark generation. The protective ring is fixed to the cylinder using a “dovetail groove” structure, ensuring that the copper ring will never fall off. The copper ring material undergoes a special treatment process, and the ring is secured with bolts rather than rivets, thereby eliminating safety hazards caused by residual stresses from riveting. This resolves the issue of copper band protective rings falling off and completely eliminates potential safety risks. The friction spark safety performance of the metallic materials used for the impeller blades and protective rings in the main ventilator must comply with the requirements specified in GB/T 13813. A certificate of compliance for friction sparks generated by metallic materials has been obtained.

6) Fan braking device: Both the primary and secondary main units of the fan are equipped with reliable braking devices. The braking device employs manual radial braking, ensuring that the motor shaft is not subjected to axial forces during braking, thereby improving the load distribution on the motor bearings. After shutdown, the fan can quickly reverse its airflow; the reversing time complies with the requirements of the "Coal Mine Safety Regulations," staying within 10 minutes. The fan uses a direct-reversal method via motor reversal for airflow reversal, and the reversed airflow rate exceeds 70% of the forward airflow rate.