Underground Air Ventilation FAQ
What advantages does the Minetek ventilation axial fan offer? • Operating Range: Minetek primary and secondary fans are capable of an air volume change of 15-115%. • Single Speed: Minetek fans are a single speed, with air output regulated by the POD system. No VSD is required. • VSD: There is no requirement for a Variable Speed Drive to increase or decrease the air output of the system. • Power Consumption: Savings are typically around 50% on power consumption • POD: Power, Performance, Pressure on Demand means the right amount of air, where you need it. • Robust: The Minetek fan is designed to withstand the rigorous demands of the mining environment. • Blade Wear: The high-pressure steel impulse bladed impeller is at the forefront of technology and allows for operation at pressures previously thought impractical for an axial fan. • VOD Controls: There is no requirement for a Ventilation on Demand system. • No Fan Stall: The Minetek axial primary and secondary fans can start on no load, with a gradual output increase regulated by the POD system. • No Loss of Air: The no stall capability in the Minetek fan means no loss of air. • Reduction in Capital Costs: Less fans are required when using the Minetek system, particularly in multiple heading ventilation applications.
What applications are the Minetek fans suited to? • • • •
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Secondary/Auxiliary Fans Main Primary Fans Booster/Intake Fans Development Fans
• • • •
Secondary/Auxiliary Fans Main Primary Fans Booster/Intake Fans Development Fans
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What are the technical specifications on the Primary and Secondary fans?
SECONDARY/AUXILIARY FAN RANGE
PRIMARY/BOOSTER/MAIN FAN RANGE
Power Range
90kW – 375kW
Power Range
150kW – 2,000kW
Volume
10 – 100m3/s
Volume
50 – 1,000m3/s
Pressure
200Pa – 6,500Pa
Pressure
500Pa – 12,000Pa
Efficiency
>85%
Efficiency
>85%
Why are Variable Speed Drive risky? Current available axial fans have one duty curve at any given time. To change this would require the use of a Variable Speed Drive (VSD). The issues associated with VSD include: • Altering the speed of the impeller will lead to excitation of an impeller or fan blade natural frequency which will result in a very premature failure of the fan. • VSD systems generate heat. To mitigate the risk of heat in an underground environment, the system must be mounted in a purpose built, stand-alone cabinet. To dissipate the heat buildup in the cabinet, vents must be cut into the cabinet, which compromises the IP rating of the cabinet. • Once the cabinet has been compromised by the vent, dust ingress inevitably leads to the failure of the VSD. • The heat load of a VSD accounts for 3-5% of its total power. • Harmonic imbalances on start up using a VSD system will result in premature failure.
How does the Minetek system perform as a DOL (Direct On Line) start up? The Minetek system does not use a DOL start up process. The system starts on no load, closed position, and ramps up to the required performance parameters as required by site.
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What is POD? POD stands for Performance, Power & Pressure on Demand. The POD unit is integrated within the fan and allows the fan to be regulated from very low flow requirements through to more than double the duty of a traditional vane axial fan. The POD offers a new level of control over primary and secondary vent fans, only previously partially available with expensive and high maintenance VSD’s. The POD system allows the fan operation to be altered if the resistance is changed for any reason. This will ensure all working areas still receive the required air flow. The POD system can be over opened, (i.e. to 115%), for blasting and can increase the airflow by up to an additional 30m3/s. This results in re-entry times being reduced offering increased production. The POD controller is regulated on start-up for vent bag inflation, negating the need for soft starters. No bump (jog) start is required.
What is MAC? The Mine Air Control system in an option offered by Minetek. The system consists of a smart controller in each fan starter panel that controls the output at each heading. To achieve this, it receives signals from the flow meters and uses regulators to later the flow in the drive. The entire MAC system is designed to default to a pre-set flow at any given drive. The system can be programmed to manage several working headings. Instrumentation can monitor pressure increasing or decreasing, regulating different headings. This system provides greater flexibility of air delivery and control which in turn maximises power savings.
What cost savings/efficiencies does the Minetek system offer? • No requirement for expensive, unreliable VSD controls: Constant Fan Speed. • Faster re-entry times: Move over 65m3/s to evacuate gasses and increase production and development times. • No bump starts required. Fan starts on no-load POD setting: Therefore, massive start up power saving, and also avoids duct damage from whip tearing on start up. • Lower maintenance cost with a single fan when managing multiple headings.
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What options are available with the Minetek system? • Allen Bradley Panel View HML – MAC Panel for POD and ventilation control system. • Integrated RFID Tag reader including 10 x RFID Tags (to suit single heading). • 2 x Duct In-Flow Meters. • 2 x Pressure Sensors • Integration with existing mine feedback comms such as WIFI, Leeky Feeder etc
Do Minetek offer a complete turn-key solution? Yes. Minetek will attend site, assess the requirements, and offer a full solution which includes supply, install, commission and support. A final scope of works can be presented once a site evaluation has been completed.
Twin 1100 kW, 1000V motors with airflow capacity of 350m3/sec@4200Pa “This is the first fan of this size and with this technology to be installed in Australia and in record time!”
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