Advantages and disadvantages of piston machine and screw machine
Advantages of traditional air compressor:
1. The intake and exhaust pressures cover a wide range.
2. The coverage of air volume is also quite extensive.
3. In the application field of small air volume and high pressure, the reciprocating air compressor can be used as a supercharger
4. The air tightness is quite good, so it is also suitable for special gases other than compressed air or nitrogen.
5. Adopt high-strength rotor, low speed, sturdiness and durability, and low failure rate in continuous use. 6. Each stage of multi-cylinder double-acting adopts multi-stage to control the benefit of throttling is quite significant.
Disadvantages of traditional air compressor:
1. Serious waste of electric energy
In traditional loading and unloading air compressors, energy is mainly wasted: 1) Electricity consumption during loading
After the pressure reaches the required working pressure, the traditional control method determines that the pressure will continue to rise until the pressure is unloaded. During the pressurization process, more heat and noise will be generated, which will lead to power loss. On the other hand, before the high-pressure gas enters the pneumatic components, its pressure needs to be reduced by a pressure reducing valve, which also consumes energy.
2) Power consumption during unloading
When the unloading pressure is reached, the air compressor automatically opens the unloading valve to make the motor idling, causing serious energy waste. The power consumption when the air compressor is unloaded accounts for about 30% to 50% of the full load, which shows that the traditional air compressor has obvious energy-saving space.
2. Power frequency start-up impulse current is large
Although the main motor adopts Y-△ decompression starting, the starting current is still very large, which has a large impact on the grid, which is easy to cause grid instability and threaten the operation safety of other electrical equipment. The impact of several times the rated current may cause other equipment to be abnormal. .
3. The pressure is unstable and the degree of automation is low
The traditional air compressor has a low degree of automation, and the output pressure is adjusted by the control of the loading and unloading valve and the regulating valve. The adjustment speed is slow, the fluctuation is large, the accuracy is low, and the output pressure is unstable.
4. Large amount of equipment maintenance
The power frequency starting current of the air compressor is large, up to 5-8 times the rated current. The working mode determines that the loading and unloading valve will inevitably move repeatedly, the components are easy to age, the power frequency runs at a high speed, the bearing wears large, and the equipment maintenance is large.
5. Loud noise
Continuous high-speed operation of power frequency, additional pressure exceeding the required working pressure, repeated loading and unloading, directly lead to high noise of power frequency operation.
Advantages of screw air compressor:
1. The starting current is small, and there is no impact on the grid
The frequency converter can make the current of the motor start and load smoothly without any impact; it can make the motor realize a soft stop, avoid the harm caused by the reverse current, and help to extend the service life of the equipment;
2. Stable output pressure
After the frequency conversion control system is adopted, the pressure of the gas in the gas supply pipeline can be monitored in real time, so that the pressure of the gas in the gas supply pipeline can be kept constant, and the production efficiency and product quality can be improved;
3. Small amount of equipment maintenance
The frequency conversion starting current of the air compressor is small, less than 2 times the rated current, and the loading and unloading valve does not need to be operated repeatedly. The frequency conversion air compressor automatically adjusts the motor speed according to the air consumption. The operation frequency is low, the speed is slow, the bearing wear is small, and the equipment life is prolonged and maintained The workload becomes smaller.
4. Low noise
The frequency conversion provides energy according to the gas demand without too much energy loss. The motor running frequency is low, and the mechanical rotation noise is therefore reduced. Because the frequency conversion adjusts the motor speed, there is no need to repeatedly load and unload, and the noise of frequent loading and unloading is also eliminated. , Continue to pressurize, and the noise caused by unstable air pressure also disappears.
The disadvantages are:
1. There must be a gap between the female and male screws, resulting in unsatisfactory air tightness.
2. The air compressor body only has a life span of 3 to 5 years, and the technology for replacing and repairing the air compressor body is often retained by the original manufacturer. Therefore, the cost of replacing the entire set of air compressor bodies will generally exceed 60% of the purchase of a new machine.
3. Long-term shutdown after long-term operation may cause the rotor in the air compressor body to get stuck.
Performance comparison of screw machine and piston machine
Old-fashioned piston air compressors have poor operating efficiency and reliability. Piston air compressor is a model that most users are very familiar with. It was a product that everyone recognized in the very early stage. However, with the continuous innovation of technology and the emergence of new types of air compressors, the disadvantages of piston air compressors More and more prominent, compared with screw air compressor:
a. Piston air compressors have many vulnerable parts such as valves, pistons, piston rings, connecting rod bushes, etc., and the reliability of continuous operation is poor. On the one hand, it will affect production and on the other hand, it will increase maintenance and management costs.
b. Compared with screw air compressors, piston air compressors have low efficiency, especially for long-term continuous operation, and their economy is worse. Since many of the compression chambers formed by the piston air compressor are vulnerable parts, the wear and damage of these vulnerable parts will cause greater leakage during gas compression, and ultimately reduce the efficiency of the compressor. Since there are no vulnerable parts that affect the efficiency of the machine in the screw compressor, the pair of rotors for compression will not wear out due to the characteristics of their own structure. Therefore, the economy of long-term continuous operation is much better than that of piston air compressors.
c. The piston type air compressor is a reciprocating motion mechanism, and there is an inertia force that cannot be eliminated. Therefore, during operation, the vibration is large and the noise is high. The larger piston type air compressor requires a special fixed foundation for installation. The screw air compressor is a rotary motion mechanism with good balance, low vibration, low noise, no foundation installation, and at the same time avoiding pollution to the working environment.
d. The piston type air compressor is a reciprocating intermittent air supply, with large air flow pulsation during operation, high speed of the screw compressor, stable air delivery, and no air flow pulsation, which can meet the needs of users who require higher air volume.
e. Piston-type air compressors basically have no automatic control system. Screw compressors have complete automatic control and protection systems. They are electromechanical integrated products, which facilitate equipment maintenance and management, while also minimizing energy consumption.
f. The screw air compressor is a highly centralized product with an overall structure. It has a small footprint and does not have the complicated piping system of a piston air compressor, which can beautify the company's production environment.
There are too many types of models used and they are too scattered, which is not convenient for equipment management, but also increases the number of wearing parts, which will inevitably increase the cost of normal operation. At the same time, the scattered layout exacerbated the pollution to the production environment.
Poor air supply quality and high fuel consumption. Piston-type air compressors suffer from wear and tear of piston rings. Even though there is an oil scraper ring on the piston, a lot of lubricating oil will escape into the cylinder and be discharged with the gas. This will reduce the quality of the gas on the one hand. On the other hand, it also increases fuel consumption, and the inevitable leakage of lubricating oil will also increase fuel consumption and pollute the environment. The screw air compressor has an efficient oil and gas separation system and filtering equipment, no wearing parts, high air supply quality and low fuel consumption. It is precisely based on the above situation that the relevant state department issued a document in 2000, requiring domestic enterprises to gradually phase out piston air compressors with high operating costs and low reliability in the use of medium and low pressure air compressors, and replace them with efficient screw compressors. It has become a reality in developed countries.
Based on the above, in order to reduce production costs, increase economic benefits, facilitate equipment management, beautify the company's environment, and improve the company's image, the existing piston air compressors are eliminated with high-efficiency and high-reliability screw compressors, and an advanced nature is built. , Economical air compressor station is the inevitable trend of your company's growing strength.
