On April 16, 2021, General Secretary Xi Jinping pointed out at a video summit with the leaders of France and Germany that China will strive to peak carbon dioxide emissions by 2030 and achieve carbon neutrality by 2060, which means that China, as the world's largest developing country, will complete the world's highest carbon emission intensity reduction and achieve carbon peak to carbon neutrality in the shortest time in global history, which will undoubtedly be a tough battle.
In this context, the problem of high energy consumption of air compressor system has gradually become prominent, and new requirements have been put forward for air compressor energy-saving technology. The energy consumption of the air compressor system is mainly reflected in: 1. high energy consumption of air compressor equipment; 2. The host is seriously leaked; 3. Large pressure loss (e.g., pressure loss of gas pipelines, etc.); 4. Unreasonable layout; 5. Lack of dynamic regulation; 6. Lack of energy recovery solutions.
1. Three ways to save energy in air compressors Everyone has been talking about energy saving, how to save energy? There are three main ways: one is to improve the efficiency of power utilization; second, high-efficiency drives; The third is to reduce the specific power of the host.
Way 1: Improve the efficiency of power utilization

When we do energy saving, we must do every link in a timely manner and do not ignore the available opportunities. As we all know, the west-to-east power transmission is the use of high-voltage transmission technology, why not use low voltage? Because the loss of low-voltage transmission is too great. Therefore, one of the strategies to improve power utilization is to reduce reactive power losses, and the solution is to remove the transformer and use a high-voltage motor. After all, the reactive power loss of a 10kV to 380V transformer is still quite serious. Of course, for low-power air compressors, it is not recommended to use voltages above 6kV or 10kV, and it is recommended to use them in the power range above 200kW.

Strategy 2: Reduce line loss Solution: High-voltage transmission

Cables used to transmit electricity also consume electricity. During the operation of the air compressor, we will find that the cable is hot when we measure the temperature of the cable. Where does its heat come from? It must be converted by electrical energy. However, due to the small transmission current of the high-voltage machine, the cable basically does not heat up.

The strategy to improve the efficiency of power utilization is to improve the utilization rate of electricity by using high-voltage electricity.

Path 2: Efficient drive

Usually the energy-saving way of the motor is frequency conversion, so the trend of the air compressor industry in the past decade is to use permanent magnet frequency conversion technology to improve the energy efficiency level of the compressor. Permanent magnet frequency conversion has two advantages, one is that it can reduce losses by eliminating the excitation process; Second, it can be dynamically regulated with the change of air volume. Therefore, the core of Path 2 is to use permanent magnet frequency conversion technology to achieve energy saving.

Way 3: Reduce the specific power of the host

At the Shanghai International Compressor & Equipment Exhibition, there are still many single-stage compression machines. The efficiency of single-stage compression is low, so we need to improve the compression efficiency, one is to reduce the leakage between the teeth, and the other is to use a method close to isothermal compression as much as possible to improve the compression efficiency. Therefore, it is necessary to use two-stage compression technology.
To sum up, these three ways correspond to the three major energy-saving technologies in the air compressor industry, namely high pressure, permanent magnet frequency conversion and two-stage compression, so a product called high-pressure permanent magnet frequency conversion double-stage compressor will be born.
2. Analysis of the causes of energy conservation in three ways
1. Why use high voltage electricity?

Load Loss: Transformer's daily loss = (no-load loss + load loss × square of the load rate) ×24

No-load loss: When the secondary winding of the transformer is open, and the primary winding applies the rated voltage of the rated frequency sine waveform, the active power consumed is called no-load loss.

How big is the difference between using high voltage electricity and using low voltage electricity? Let's assume a data, using a common 800kVA transformer as an example. The customer may be a 2000kVA, 3150kVA, or even larger transformer, let's take a look at how much the loss of an 800kVA transformer is.

Taking the loss of an 800kVA dry-type transformer as an example, if the load factor of the transformer is 50%, the power consumption of the day is:

No-load loss is the constant loss, which is independent of the current passed through but related to the voltage to which the component is subjected.

No-load loss is to only power the transformer, without any load behind, at this time only the transformer consumes power. Its no-load loss is about 1160 watts, which can consume more than 800 kWh of electricity in a month, and these more than 800 kWh of electricity are wasted in vain. When loaded, the transformer can lose more than 5,000 watts, and more than 3,700 kWh of electricity will be wasted in a month.

Will there be such losses in high-voltage machines? There will be. For example, there is also loss in its upper transformer, such as 35kV, 110kV, and 220kV when it becomes 10kV. However, the loss is reduced by 10kV to 380V, so it will also lose a part of the power energy.

2. Why use permanent magnet synchronous motors?

Why are permanent magnet motors energy-saving? The stator coil of an ordinary asynchronous motor is energized to generate a rotating magnetic field, the magnetic field cuts the rotor, and the rotor generates an alternating current, which generates a magnetic field, and the stator magnetic field drives the rotor magnetic field to rotate. In this process, the rotor is consuming power, because the rotor itself is not magnetic, and its magnetic field energy comes by absorbing the electrical energy of the power grid. The permanent magnet variable frequency synchronous motor, because the rotor permanent magnet has its own magnetic field, when the motor stator coil is energized to generate a rotating magnetic field, the stator rotating magnetic field can directly drive the rotor magnetic field to rotate, so as to save an excitation link.

The efficiency and power factor of permanent magnet motors do not change much with the load factor and speed, while the efficiency and power factor of ordinary asynchronous motors change greatly with the load factor and speed.

3. Energy-saving principle of frequency conversion control Asynchronous motors will have low efficiency at low loads, so permanent magnet motors are more suitable for regulation. From the efficiency comparison chart of different types of motors, it can be seen that the power factor is very different.

4. Constant pressure supply Everyone understands the principle of constant pressure supply, but there are some differences when everyone does it. For example, if the customer wants an 8kgf model, it does not mean that the customer needs 8kgf constant pressure supply, if the compressor is supplied at 8kgf constant pressure, it will be a waste of energy. Commissioning is to adjust the compressor to the customer's optimal use state, not to the factory state. Therefore, the debugging link is very important, and the pressure needs to be adjusted to the pressure state of the customer's real needs, that is, the best working conditions of the air compressor.

The pressure of the air compressor does not need to be adjusted very high, because it is too high for the customer to have no use, as long as it meets the needs of the customer, it saves the original process of adding and unloading, and the excess pressure in the yellow shade area in the picture below is omitted, so this part of the work does not need to be done, so it saves electricity bills.