Main Technical Specifications of the Main Ventilator

1. Impeller Section

1) Customized Design: Based on the parameters provided by the user, we optimize the selection and perform a customized design to ensure that the fan’s performance is perfectly matched to the mine’s resistance characteristics. This guarantees high-efficiency operation under both minimum and maximum negative pressure conditions while keeping the fan well clear of the surge region.

2) Design and inspection procedures: The blades are designed based on low-speed airfoil test data from the U.S. NACA, and to ensure blade strength, a three-dimensional twisted airfoil configuration with a large cross-section is adopted. Both the blade and blade root are designed with a safety factor of at least 10 to 13 times. To verify the rationality of the blade design, vibration frequency testing and modal analysis are conducted to ensure that the operating frequencies of the first- and second-stage impellers are avoided, thereby preventing resonance. For each batch of blades, material test reports and mechanical property test reports are provided; in addition, every individual blade undergoes non-destructive testing—including X-ray radiography and magnetic particle inspection—in a dedicated flaw detection room.

3) The impeller blades are made of high-strength, premium ZL104 alloy and manufactured via metal die-pressure casting, resulting in superior blade strength and surface quality. In oxidizing environments, the material exhibits excellent corrosion resistance and wear resistance, remaining rust-free, wear-resistant, and corrosion-resistant. The critical cross-sectional strength of both the blades and blade hubs is designed with a safety factor of more than 13, and the blades undergo age-hardening treatment.

4) Blade installation and adjustment: The blades are securely and reliably fastened to the hub, which is marked with clear blade installation angle graduations at six positions—−9°, −6°, −3°, 0°, +3°, and +6°—allowing the blade angle to be freely adjusted on the spherical hub surface according to operating conditions. The blade adjustment is performed offline, one blade at a time, by using a dedicated tool to adjust the adjusting bolts and loosen the wedge-shaped pressure blocks, thereby enabling external adjustment of the blade angle to meet varying air-supply requirements at different stages.

5) Hub Manufacturing: The hub is one of the core components of the fan, characterized by a large diameter and substantial weight, as well as stringent requirements for dimensional accuracy and geometric tolerance. This makes it a challenging item in the machining process and a critical operation in fan assembly. The hub is fabricated from Q355 steel, with welds inspected by magnetic particle testing, accompanied by a corresponding magnetic particle inspection report. To ensure the coaxiality between the hub’s spindle connection hole and its outer diameter, as well as the spherical surface dimensions and hole dimensional accuracy of the hub face, our company specifically employs a large-scale CNC drop-center lathe. During hub machining, computer-programmed control enables single-setup, one-pass forming, which not only guarantees dimensional and geometric accuracy but also ensures that the surface quality fully complies with the product drawing specifications. The motor shaft extension is designed with a tapered configuration, allowing direct coupling between the motor and the impeller and achieving precise alignment through a tapered fit, thereby optimizing the convenience of impeller installation, removal, and maintenance. The impeller is secured on the motor shaft using a dual-locking system consisting of two nuts paired with two lock washers.

6) Impeller Balancing: Our company has acquired a YYW-6000 dynamic balancing machine. The hub undergoes both static and dynamic balancing tests first, followed by comprehensive static and dynamic balancing tests on the impeller until it meets the required standards, ensuring that the impeller’s balance quality grade is G4—higher than the national standard requirement of G5.6. This guarantees excellent static and dynamic performance of the fan, ensures reliable operation, and thereby ensures that the main ventilation fan’s vibration levels comply with relevant national and industry standards, specifically JB/T 8689–2014 “Vibration Testing and Limit Values for Fans,” which stipulates a maximum root-mean-square vibration velocity of ≤4.6 mm/s.

2. Main Unit and Auxiliary Components

1) The complete fan assembly comprises duct connectors, inlet collectors, primary-stage fans, secondary-stage fans, diffusers, circular-to-square transition sections, silencers, and diffusion towers. The internal flow passages of the fan are uniformly smooth; the inlet collector, flow straighteners, and fishbone heat-exchange tubes are all manufactured by cold-roll forming using dies. In addition to ensuring adequate mechanical performance—such as sufficient strength and stiffness—the fishbone heat-exchange tubes and the motor base support plates incorporate features like rounded transitions to reduce flow resistance, thereby maintaining uniform smoothness of the flow passages, lowering pressure losses, and enhancing fan performance. All supporting components adopt a symmetrical structural design, optimizing the internal flow-path configuration. The installation configuration is two fans arranged side by side in a horizontal layout. Each fan is equipped with pressure-measuring rings and other performance-testing interfaces for measuring negative pressure and airflow, which can be connected to pressure sensors to measure dynamic and static pressures as well as airflow. Vibration-measurement mounts are provided on the outer wall of the fan casing, with预留 vibration sensor mounting interfaces. The design and fabrication of all fan components shall ensure that they can withstand the structural loads required under various operating conditions: the hub material shall be no lower than Q345, with a spherical surface profile on the hub’s outer circumference and a hub web thickness of no less than 35 mm. The fan casing shall be made of Q235, with the main casing plate thickness not less than 8 mm, the motor base plate thickness not less than 25 mm, and the inner liner of the protective shroud machined and formed to a post-machining thickness of no less than 15 mm. The design and fabrication of all fan components must meet the structural-strength requirements for operation under diverse service conditions. After hub welding is completed, the entire assembly undergoes annealing; key components such as the hub and blades must undergo non-destructive testing, with inspection reports issued to guarantee quality and reliability. Fan welds shall be neat, aesthetically pleasing, and free of defects, and all critical welded joints shall be subjected to heat treatment to eliminate residual stresses.

2) Machining, anti-corrosion treatment, and rust removal of fan casings: High-quality Q235 steel is selected as the raw material, with a material certification report provided. All casings are cut using laser cutting machines, ensuring high dimensional accuracy and efficiency, thereby better guaranteeing product quality. Welding is performed exclusively using carbon dioxide shielded arc welding to minimize deformation of the fan casing, ensuring that all casings meet design specifications. Following welding, the casings undergo sandblasting to remove all visible oil, dirt, mill scale, rust, paint coatings, and other contaminants from the steel surface, thus enhancing the adhesion of both the primer and topcoat. The primer is applied in two coats; prior to shipment, an additional coat of anti-corrosion polyurethane topcoat is applied, with each primer coat having a film thickness of 30–40 μm. The final topcoat application results in a total coating thickness of 100–140 μm. The exterior color of the fan is determined according to customer requirements.

3) Noise-reduction measures for the fan: The noise generated by the fan primarily stems from motor operating noise, aerodynamic noise caused by airflow, and other mechanical noise. To address these noise sources, the fan’s flow-isolating chamber, diffuser, dedicated silencer, and diffusion tower are designed not only to optimize fan performance but also to achieve low-noise operation. Specific noise-reduction measures include the use of a two-stage silencing diffuser, row-type silencers, and built-in silencing vanes within the diffusion tower. As a result, the fan’s noise level complies with the provisions of JB/T 8690 “Noise Limits for Fans” and meets the requirements of the environmental impact assessment.