Shanxi Coal Sales and Marketing Group, Dazigou Coal Mine Main Ventilator No. 25/2*250 KW Completed and handed over smoothly, now in normal operation.

Comprehensive Introduction to Fan Technology

1) Technical performance and manufacturing of the equipment

Our company’s axial-flow fan adopts an integrated structure in which the motor is directly connected to the impeller, eliminating the need for a transmission system. This design features high efficiency, energy savings, low noise levels, and simple installation and disassembly.

The following is a brief overview of our company’s products:

1. Technical features of the product:

When designing fans, we optimize the selection based on the parameters provided by the user and carry out personalized design to ensure that the fan operates with high efficiency both in the initial and later stages.

The housing of the main unit is fabricated by welding high-quality Q235 steel plates. During welding, we employ an advanced CO2 gas-shielded welding center and an automated CNC straight-cutting machine. For corrosion protection of the fan housing, both the inner and outer surfaces undergo sandblasting to remove rust, followed by two coats of epoxy zinc-rich primer and one coat of epoxy zinc-rich topcoat. All bolts used are galvanized. These measures ensure the rigidity, quality, and service life of the fan being bid for in this project.

The fan blade is made of high-strength cast aluminum alloy, a material widely used in aerospace technology. The blade profile design is based on the latest blade profile experimental data released by the aerospace agency, featuring a three-dimensional twisted structure with a large cross-section and high strength, offering exceptional strength and a broad operational range.

The blades are manufactured using XAerospace’s most advanced production technology, ensuring product quality.

The hub of the fan is welded together from steel plates of varying thicknesses and bushings. In the design, both the blades and the hub are selected with a safety factor of 6 to 7 times, and their strength and the safe operation of the fan are thoroughly ensured through computer calculations. The welding and heat treatment processes used for the hub guarantee that it will remain deformation-free during service. Our factory’s machining equipment ensures that the angular deviation when the blades are mounted on the hub is no greater than 0.5 mm.

The fan is equipped with a dedicated explosion-proof motor. Radial and axial force values, corresponding to the ventilation parameters, are provided to the motor manufacturer to ensure that the motor bearing temperature remains within safe limits and that the motor’s service life meets the specified requirements. The motor is fitted with an oil-injection device, allowing for oiling without shutting down the motor, thus facilitating maintenance. The accompanying electrical control system features protections against phase failure, overload, and over- (or under-) voltage. It can display the temperature of the motor (stator or bearings) and provides both audible and visual alarms.

The components of the fan feature a compact structure and are equipped with vibration-damping rubber pads, ensuring a vibration velocity of ≤4.6 mm/s, which meets the requirements of the national standard.

Our company’s specially designed motor enclosure and silencer can reduce the operating noise of fans to below 85 dB(A), meeting the requirements of national standards. Moreover, they isolate the cooling airflow around explosion-proof motors from the contaminated air flow discharged by the mine’s main ventilation fan. The isolation chamber is equipped with inlet and outlet ducts that connect to the atmosphere outside the motor housing. As a result, the airflow within the duct is under negative pressure, while the cooling airflow around the motor itself is at positive pressure and communicates directly with the atmosphere, ensuring adequate heat dissipation for the motor. We have also specially designed a braking system that fully meets the requirements of Article 122 of the “Coal Mine Safety Regulations” (which stipulates the ability to reverse the airflow direction in roadways within 10 minutes).

The damper produced by our company features flexible opening and closing, low power consumption, remote or local operation capabilities, and is equipped with a manual override device.

2. Installation and Maintenance of Fans

Thanks to their direct-drive design, this series of fans has relatively low requirements for the precision of the installation foundation. Even if the ground beneath the fan settles and causes a slight tilt (generally no more than 15°), the fan can still operate normally without affecting the mine’s safe and continuous production. Moreover, this series of fans can directly reverse their rotation to achieve reverse airflow, with a reverse airflow rate of ≥60%, exceeding the requirement stipulated in Article 122 of the "Coal Mine Safety Regulations" (which states that after the airflow direction is reversed, the supply air volume of the main ventilation fan should not be less than 40% of the normal supply air volume). As a result, there is no need to construct a dedicated reverse-air duct, thereby reducing installation costs. Simply put, when installing the fan, all you need to do is lay two rails on a solid foundation, place the fan on top of them, and connect one end of the fan to the mine’s ventilation outlet. Since the fan adopts a direct-drive rotor-motor configuration, maintenance is straightforward—typically, you only need to lubricate the motor at regular intervals according to the specified schedule and quantity.

The roller-type installation of the fan allows its components to be pulled apart along the axial direction of the fan, making blade angle adjustment exceptionally easy.

3. Quality Control of Critical Components

From raw material procurement to product shipment, every single process in our company is subject to rigorous quality control in strict accordance with the ISO9001 standard. In particular, critical components such as motors, hubs, and blades are subjected to especially stringent quality checks.

The motor配套 with the fan can be selected from well-known domestic brands, and bearings from Sweden’s SKF or FNG can also be used. This ensures a long service life for the fan’s power system.

After the impeller hub is completed, it undergoes both static and dynamic balance tests, and a detailed report is prepared. The dynamic balance grade is G4, which exceeds the national industry standard requirement of G6.3, thereby ensuring smooth operation of the fan and extending the service life of the motor bearings.

Every process—from material selection and stamping to installation and commissioning—is rigorously controlled, with multiple layers of quality inspection at each stage, ensuring the blades meet both quality standards and operational requirements.

2) Product Quality Commitment and Guarantee

Our company’s fans fully meet your requirements for various parameters such as air volume and air pressure, and have a service life of over 25 years. The following are our product quality assurance measures:

From the receipt of raw materials to the shipment of finished products, all processes are rigorously inspected in accordance with the ISO9001 international quality system standards. The production, inspection, testing, and acceptance of each process are jointly carried out by the Production Department, Quality Inspection Department, and Technical Department, with detailed records kept and filed. We provide end-to-end tracking, quality management, and service for every customer’s product. For example, the design and manufacture of fans comply with GB/T 3235 “Basic Types, Dimensions, Parameters, and Performance Curves of Fans” and GB/T 3235 “Basic Types, Dimensions, and Parameters of Fans.” Purchased motors must meet the technical requirements specified in GB/T 3836.1. Product outgoing tests are conducted according to the GB/T 1236—2000 standard, covering ductwork processing, measurement point layout, raw data acquisition, data calculation, and result reporting. Steel materials must be accompanied by material certification reports provided by the manufacturer, and we also commission nationally recognized, qualified inspection agencies to verify the material composition; only materials that meet the required standards can be used. For matched motors, the motor manufacturer must provide performance test reports and no-load test reports. We provide users with non-destructive testing reports for fan blades. Fan impellers undergo two-sided dynamic balancing tests in accordance with GB/T 9101 “Balancing of Fan Rotors,” and the outgoing dynamic balancing grade must meet or exceed G4, surpassing the national standard requirements. Upon shipment, we provide users with dynamic balancing test reports for the impellers. The exterior painting of fans is performed according to the technical requirements specified in JB/T 6886 “Technical Conditions for Fan Painting.” Fan nameplates are manufactured in compliance with the requirements of GB/T 13306 “Nameplates.”

3) Main features of the fan

1. Impeller arrangement: A direct-drive structure is adopted, in which the impeller is fixed to the hub via a key connection through the shaft.

2. Refer to the attached drawings for the overall dimensions of the fan unit, which include the inlet collector, primary fan, secondary fan, diffuser, round-to-square transition, diffusion tower, and silencer.

3. The fan is equipped with a braking device that enables normal startup and reverse airflow within 5 minutes, with the reverse airflow rate exceeding 60% of the forward airflow rate.

4. During fan design, we optimize the selection based on the parameters provided by the user and carry out personalized design to ensure that the fan operates with high efficiency both in the initial and later stages.

5. The fan casing is fabricated by welding Q235 steel plates. The fan casing undergoes the following anti-corrosion treatment: both the inner and outer surfaces are sandblasted to remove rust, followed by two coats of epoxy zinc-rich primer and one coat of epoxy zinc topcoat. All bolts are galvanized.

6. The silencing orifice plates all feature orifices with a diameter of ≥3 mm, effectively extending their service life and reducing subsequent replacement costs.

7. The host casing and the rotating parts of the impeller are equipped with protective rings made of H62 brass, ensuring safety and reliability.

8. Differences in blade fixing methods:

Aluminum alloy blades are secured using a press-fit clamp method, which is complex to manufacture but provides a firm and reliable hold and is easy to operate. Wing-shaped blades, on the other hand, are typically fixed with nuts or other methods, making them less secure and prone to loosening during operation.

4) Improvement measures and application of new technologies

1. In the design of conventional motors, the cooling fan’s heat dissipation capacity (ventilation cross-section) is calculated based on natural ventilation conditions. However, in fan motors installed within isolation chambers, ventilation conditions are severely restricted. To address the issue of poor ventilation, our company has taken two key measures: First, we have increased the length of the isolation chamber (so that the airflow does not abruptly turn 90 degrees and can flow smoothly without significant turbulence); and we have also expanded the ventilation cross-section of the fresh-air duct (typically to more than twice the motor’s cross-sectional area). Second, we have independently designed the motor’s cooling air passages—leveraging our company’s own design expertise and strengths—to ensure that airflow enters through the intake port and smoothly carries away the heated air from the motor via the exhaust port.

2. By adopting a streamlined diffusion tower, the noise at the fan outlet has been reduced to some extent, and the efficiency has improved by 2–4%.