A Comprehensive Comparison of Rotary Screw Air Compressors and Piston Compressors
Trying to decide between a rotary screw air compressor and a piston compressor? This comprehensive comparison guide breaks down the pros and cons of each.
Air compressors are important equipment in mining operations and have positive implications in practical applications. There are two types of air compressors: piston and rotary screw. In research, a comparison of their characteristics and usage has been conducted from multiple perspectives to facilitate better selection and application in actual production.
Automation Control
Piston compressors do not come with an automated control system, although some have been retrofitted with one. They typically operate in three modes: half-load, no-load, and full-load. In practical design, piston compressors have a 20% margin, with actual gas usage at 80% of the compressor station’s capacity. However, when there are large fluctuations in gas usage, piston compressors cannot adjust to the actual usage, resulting in frequent switching between load modes, which can affect the lifespan of the equipment. Additionally, starting and stopping the compressor can cause a significant impact on the power grid, and the process of releasing gas manually before restarting can be cumbersome.
In contrast, rotary screw compressors have a more sophisticated protection system and automated control, making them an integrated electromechanical product that is well-suited for equipment management and maintenance. They can maintain relatively stable values within a wide range of exhaust pressure, speed, and exhaust volume, with minimal changes in specific power. In practical applications, they can operate at around 50% capacity and avoid frequent shutdowns when there are large fluctuations in gas usage. Furthermore, they can be controlled automatically without human intervention, with multiple devices being stopped, loaded, started, and unloaded based on actual gas usage, making them highly efficient in terms of automation.
Vibration and Noise
Piston compressors have a reciprocating motion mechanism that creates inertia forces that cannot be completely eliminated during operation, resulting in significant noise and vibration. This requires the installation of a reinforced concrete foundation. Additionally, because of their intermittent air supply, they create significant airflow pulsations, requiring the installation of large air storage tanks. On the other hand, rotary screw compressors have a rotating motion mechanism that provides better balance, lower noise and vibration, and does not require a foundation. They also have lower airflow pulsations and a smoother air supply, which can meet high-volume demands without the need for special requirements or large air storage tanks.
Reliability and Stability
Piston compressors have a more complex internal structure with a lot of piping systems that can easily be damaged during continuous operation, leading to reliability and stability issues. This not only affects production but also increases management and maintenance costs. On the other hand, rotary screw compressors have a simpler structure with no easily damaged parts and less complex piping systems. They have better reliability and stability, and can effectively reduce maintenance costs and losses. In terms of cost-effectiveness, rotary screw compressors perform better.
Operating Efficiency
Piston air compressors have some drawbacks in terms of operating efficiency and long-term continuous operation. They have many vulnerable parts in the compression chamber, and any damage or wear can cause significant gas leakage during compression, affecting efficiency and air volume. If the cooling system is severely scaled due to water factors, it can cause high exhaust temperatures, even leading to explosion and combustion of the exhaust pipeline and body. Additionally, when the piston compressor stops and restarts, it requires manual release of the gas before restarting.
In contrast, rotary screw air compressors do not have vulnerable parts that can affect production efficiency. During compression, there is no direct contact between the casing and the screw rotor, so there is no wear and tear. Although the screw rotor has a large radial and axial force, it does not have a significant impact. The bearing life directly affects the life of the screw compressor. In the current market, different screw compressors use thrust bearings to offset axial forces and apply high-precision SKF bearings, with a lifespan of about 60,000 to 120,000 hours. In practical applications, as long as regular maintenance is ensured and lubricating oil and “three filters” are regularly replaced, there will be no failures, and they will perform better in terms of operating efficiency and stability.
Specific Power Fuel Consumption
Compared to piston machines, rotary screw air compressors have a higher specific power. When both are new, screw machines do not have an advantage in specific power, but new piston machines perform better in parameters such as exhaust pressure, specific power, and exhaust volume. However, when the equipment is in operation and has a certain degree of wear, the efficiency of piston machines will decrease, and therefore the advantages of screw machines will be reflected.
