Now the screw compressor energy consumption is huge, the general factory electricity charge high 70% of electricity from the consumption of air compressor, so energy saving is imperative, then what air compressor energy saving?

1. Energy efficiency level

It is assumed that according to the model with rated power of 37kW, the rotating speed is 3660rpm, the exhaust pressure is 0.8mpa, and the displacement Qo=5.84m cubed /min

A. The total input power of the permanent magnet synchronous frequency conversion model is measured as Pi= 40.36kw, and then the total input specific power is: qi=Pi/Qo=40.36/5.84=6.91

B. The input power of ordinary induction frequency machine is measured as Pi= 43.64kw, and the input specific power of the whole machine is qi=Pi/Qo=43.64/5.84=7.47

According to the standard of screw air compressor in gb15193-2009 energy efficiency limit and energy efficiency grade of volumetric air compressor, the energy efficiency of level 1 is the input power qi < 7.2, and the energy efficiency of level 2 is the input power 7.2≤qi < 8.1, so the permanent magnet synchronous machine is the energy efficiency of level 1, and the ordinary asynchronous machine can only reach the energy efficiency of level 2.

Two, the air compressor several kinds of air volume adjustment analysis

In order to make the air compressor exhaust and user air consumption to reach a balance, the common air compressor air volume regulation for the intake throttle regulation, loading/unloading regulation and other ways, due to the existence of intake throttle led to too much vacuum, as well as loading and unloading pressure loss and other reasons, the energy saving effect of these ways is not ideal.

Later, due to the development of motor frequency conversion control technology, the motor speed control regulation mode appeared, which could make the power consumption of air compressor and exhaust volume change linearly and proportionally. At present, it is gradually popularized. However, this control method has the following disadvantages:

When the speed and load of ordinary induction motor are less than the rated point of the design, the efficiency of the motor drops obviously, and the larger the difference, the more obvious the efficiency drop

When the ordinary induction motor runs at a lower frequency, the problem of insufficient output torque will appear, making the inverter appear "motor torque overload" and the fault of jumping machine

Ordinary induction motor in a lower frequency when running will also appear in the rotational speed instability, vibration noise increase, heat increase and other phenomena.

Even the current vector control can not completely eliminate these shortcomings.

Now a new control method for permanent magnet motor + use special variable frequency drive control method, has high efficiency and have always been able to keep at a high level, any speed under constant torque operation, speed stability, fast response speed change (from zero to rated speed acceleration time is less than 50 ms, and there is no impact current), low noise advantages.

3. Energy saving effect

Also according to the previous rated power of 37kW for the two models, when the load rate is only 60%, the input power of the power frequency model controlled by ordinary air intake throttling is 38.2kw, and the shaft power of the permanent magnet frequency conversion model is 23.6kw, with the power saving rate reaching 37.5%.

If it works 4,000 hours per year, the annual electricity cost of ordinary asynchronous frequency machine is 107,200 yuan, and if the permanent magnet synchronous frequency machine is used, the annual electricity cost is 65,800 yuan, and the annual electricity cost saved is 41,400 yuan.