How to ensure the stable operation of magnetic suspension blower in subway tunnel?

In order to ensure the stable operation of magnetic levitation blower in subway tunnel, it is necessary to formulate targeted measures from installation, environmental control, system monitoring, maintenance management and other aspects in combination with equipment characteristics, tunnel environmental characteristics and operation and maintenance requirements, as follows:

First, optimize the installation and basic configuration

Adapting to tunnel installation environment

Although the magnetic suspension blower does not need a complex foundation, it needs to ensure that the installation plane is horizontal and stable to avoid equipment displacement caused by slight settlement or vibration of the tunnel structure (such as when the train passes). Damping pads or fixed brackets can be used to enhance stability and reduce the influence of external vibration on the fan.

The installation position should be far away from the area where water is easy to accumulate, dust accumulates or corrosive gases (such as trace harmful gases generated by subway braking) in the tunnel. If necessary, protective enclosures or isolation compartments should be set up to avoid pollutants from directly contacting the equipment.

Reasonable layout of pipelines and connections

The design of inlet and outlet air ducts should reduce resistance loss, avoid sharp turns, sudden change of pipe diameter and other structures, ensure stable air flow and reduce fan load fluctuation.

Flexible connection (such as rubber soft connection) is adopted at the interface between the pipeline and the fan to reduce the transmission of pipeline vibration to the fan body and avoid affecting the stable suspension of the magnetic bearing.

Second, strictly control the operating environment parameters

Temperature and humidity management

The ambient temperature in the subway tunnel may fluctuate with the train operation and the external climate (high temperature in summer and low temperature in winter), so it is necessary to ensure that the ambient temperature of the fan is within the allowable range of the equipment (usually-10℃~40℃). The local environment can be adjusted through the tunnel ventilation system, or a cooling device (such as forced air cooling and water cooling module) can be installed for the fan to prevent the motor or control system from being overloaded due to high temperature.

Humidity should be controlled below 85% (no condensation) to avoid short circuit of electrical components and corrosion of metal parts caused by humidity. If necessary, install dehumidifier or put desiccant in the control cabinet.

Prevention and control of dust and pollutants

There may be dust and particles in the tunnel (such as metal chips produced by rail friction), so it is necessary to clean the air inlet filter of the fan regularly (weekly inspection and monthly replacement are recommended) to prevent insufficient air intake and abnormal air pressure caused by clogged filter screen.

In view of the possible oil stains and corrosive gases (such as a small amount of hydrogen sulfide) in the tunnel, an efficient filter device (such as activated carbon filter screen) can be added at the front end of the air inlet to protect the core components such as magnetic bearing and impeller.

Third, strengthen system monitoring and intelligent protection

Improve the real-time monitoring system

Using the intelligent control system of magnetic suspension blower, the core parameters, including rotational speed, wind pressure, air volume, bearing temperature, motor temperature, vibration value, current and voltage, are monitored in real time, and parameter thresholds (such as upper temperature limit and excessive vibration value) are set, and an alarm will be triggered immediately if it exceeds the standard.

Access to the subway integrated monitoring platform (SCADA system) to realize remote data transmission and centralized monitoring, so that the operation and maintenance personnel can grasp the running status of the equipment at any time and find abnormalities in time.

Set up multiple security protection mechanisms

The equipment itself should have active protection functions, such as over-current protection, over-voltage protection, under-voltage protection, over-temperature shutdown, vibration over-limit shutdown, bearing fault self-diagnosis, etc., to ensure that the power supply is automatically cut off or the operation is slowed down in case of abnormality, so as to avoid the fault from expanding.

In view of tunnel emergencies (such as fire and water flooding), it is necessary to link the tunnel fire fighting system. When smoke, high temperature or water accumulation are detected, the fan power supply will be automatically cut off and emergency isolation measures will be started.

Fourth, standardize operation and maintenance and regular maintenance

Main points of daily maintenance

Check whether the operation parameters are stable, abnormal sound and alarm information through the monitoring system every day; Check the status of filter, tightness of pipeline connection and operation of radiator on site every week.

Regularly clean the equipment surface and cooling fins to ensure smooth cooling; Check whether the cable connector and grounding wire are loose to prevent electrical failure caused by poor contact.

Periodic in-depth maintenance

According to the requirements of the equipment manual, a comprehensive overhaul shall be conducted every six months to one year, including checking the accuracy of sensors (such as temperature and vibration sensors), checking the clearance of magnetic bearing and the calibration of control system, testing the dynamic balance of impeller (to avoid slight deformation caused by long-term operation), and evaluating the insulation performance of motor.

Upgrade the control system software, optimize the operation algorithm, and ensure that it can adapt to the changes of subway tunnel working conditions (such as the difference of morning and evening peak ventilation demand).

Backup plan and emergency response

The ventilation system of subway tunnel is usually designed redundantly, so it is suggested to configure standby magnetic levitation blower or switch to the emergency circuit of traditional blower, which can be quickly switched when the main blower fails to ensure uninterrupted tunnel ventilation.

Make an emergency plan, define the fault handling process (such as bearing alarm, sudden drop of wind pressure, etc.), and equip a professional operation and maintenance team to ensure the response within 30 minutes after the fault occurs and complete the preliminary treatment within 2 hours.

Five, adapt to the special working conditions of the tunnel debugging

The ventilation demand of subway tunnel varies greatly with the train operation density and time (such as peak/flat peak), so it is necessary to preset multi-stage operation modes (such as high air volume mode and energy-saving mode) through the control system in advance to ensure the smooth switching of fans within the speed adjustment range and avoid the instability of magnetic bearing due to sudden load change.

Regularly simulate the extreme working conditions of the tunnel (such as high temperature, high humidity and short-term overload), test the adaptability of the equipment and the effectiveness of the protection mechanism, and verify the stability of the system.

Through the above measures, an all-round guarantee system can be constructed from the dimensions of environmental adaptation, real-time monitoring, active protection and standardized operation and maintenance, so as to minimize the influence of the complex environment of the subway tunnel on the magnetic levitation blower, ensure its long-term stable operation and meet the reliability requirements of tunnel ventilation.