VDK PLANT

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APPLICATION OF VDK PLANTS

Axial main mine fan of VDK series with a rated flow from 20 to 900 m3/s and a rated total pressure from 1100 to 7000 Pa for air density of 1, 2 kg/m3, designed for the mines main ventilation systems used in the mining industry and operated under atmospheric conditions with a temperature of transported air from 228 to 323К, dust content up to 150 mg/m3 and relative humidity up to 98% (at 298К (+250С)) at the elevation up to 1000 m above the sea level.

Climatic design U (moderate climate), placement category 3.1 according to GOST 15150.

hatch adapter

horizontal shaft cover

volute chamber

swivel shaft cover

first stage fan

second stage fan

pipe with service hatch

VDK structure

The fan plant with axial two-stage counter-rotating fans VDK consists of the first stage main fan device, the second stage main fan device (including housing, bed, electric motor, impellers, brake unit), volute chamber pipe, volute chamber tower, sound-absorbing assembly to switch shaft covers yoke with winch, and starting and controlling equipment.

First and second stage fans include: split housing (upper, lower), protective sheath for electric motor and braking device, electric motor with impeller, and braking device.

First and second stage fans are installed coaxially to the calculated technical gap between the end planes of the impellers, which are rotated in the opposite direction. This design eliminates the use of guiding devices of conventional axial fans. In this regard, the VDK fan has a higher efficiency factor (above 80%).

A special three-phase asynchronous electric motor of YBF type with the explosion protection category dl, protection category IP44, insulation class F, output box protection category IP54, and temperature exceeding class B is used to drive the VDK fan impellers.

The electric motor is equipped with a bearing and stator temperature measuring device and a heating device to facilitate starting in winter.

Each main electric motor and braking device is mounted inside an enclosed streamlined shell (envelope) located inside the fan housing. This eliminates the contact of electric motors with mine air and provides an additional explosion protection. The main motors are cooled by atmospheric air through special supply and exhaust ducts.

The electric motor design allows for partial replenishment or replacement of grease in the rotor bearing assemblies by means of oil-filling pipelines led from the bearing assemblies outside the fan housing.

To reduce noise, the housings of the first and second stage fans are equipped with sound-absorbing baffles mounted on the side surfaces. The average noise level at a distance of 1 meter does not exceed 85 dB.

A flow stabilizer device is installed in the ventilating pipe to ensure fan performance and surge-free fan operation.

Two wheels rotating in opposite directions function both as impellers and directing air flow from one wheel to the other, which, compared to conventional axial fans, avoids energy loss on the middle and rear guiding devices and between the electric motor and the impeller.

Wide-range regulation of the VDK fan operation mode is carried out by changing the number of operating electric motors (simultaneous operation of one of the two is possible), the angle of wheel blades installation, and by changing the wheels and type of electric motors.

There are 5 holes on the wheel drum to indicate the blade angle, which correspond to angles: 25°, 30°, 35°, 40°, 45°, by which the blade angles can be changed when the amount of mine air needs to be changed.

TECHNICAL SPECIFICATIONS

features

This fan assembly can provide reversal of air stream during operation of one or two impellers by reversing the direction of rotation.

In this case, the air stream flow is more than 70% of the flow during normal operation, which meets the requirement of PB 05-618-03, and eliminates the need to build ducts and structures to reverse the air stream.

The counter rotation design due to the balanced moments of rotation does not require a large foundation, which leads to significant cost savings. Upon customer's request, the ventilation units can be equipped with wheels and installed directly on the rails without foundation bolts.

To ensure greater safety of the VDK fan application and to select the optimal design parameters of the main fan components, the strength calculations using the methods of stress concentration analysis, identification of limiting deformed states of the main components, and parts of the fan rotor under dynamic loading have been performed. The CAD, CFD, CAPP, and CAE software packages were used for this purpose, which allowed a detailed analysis of the occurring stresses in all fan components and the necessary design adjustments to improve mechanical properties and strength.

The electric motor shaft is manufactured with precision machining method and the seating surface is ground and polished. According to calculations, the permissible limiting speed of the impeller is 1.35 times the normal rotation speed.

The impeller blades of the VDK fan are in the shape of rounded blades and are made of 08F-n (or Q235-n) steel. Blade shanks are made of special steel with high mechanical properties and viscosity. The surface of the blade paddle is covered with a special wear-resistant coating of St23 metal alloy No. 17 by electric arc method.

The blade paddles and shanks are assembled by heat-pressing with riveted joints. After assembly, the paddles are covered with an anti-corrosion coating. Non-destructive defectoscopy is carried out in the process of paddle manufacture.

The impellers are dynamically balanced after manufacture at a blade angle of 0° and the operating mode angle.The balance quality is 4-7-5.6 points.

The service life of VDK type fans is at least 30 years. The electric motor uses SKF series bearings manufactured in Sweden with a designed service life of 100,000 hours. (10 years).

AERODYNAMIC CHARACTERISTICS