What are the working principle and advantages of centrifugal compressors?

Why isn’t anyone answering? I really need to know; please help me:victory:

Working principle: A working wheel with blades rotates on the compressor shaft; the gas that enters the working wheel is caused to rotate by these blades, thereby increasing its kinetic energy (speed) and static pressure. After exiting the working wheel, the gas moves into the diffuser, where its speed is converted into pressure, further raising the pressure. The compressed gas then passes through bends and return streams to reach the next stage of impellers, where it is compressed further to the desired pressure. A centrifugal compressor is a velocity-type compressor. Compared with other compressors, its advantages are: (1) large exhaust volume, uniform exhaust flow, and no pulsation in the airflow. ⑵High rotational speed. ⑶Lubrication is not required inside the machine. ⑷It has good sealing performance with few leakage issues. ⑸It has a flat performance curve and a wide operating range. ⑹It is easy to achieve automation and scale-up. ⑺Few vulnerable parts, low maintenance needs, and a long operational cycle. Disadvantages: (1) Poor adaptability to different operating conditions; the properties of the gas have a significant impact on operational performance. During unit startup, shutdown, and operation, the load changes significantly. ⑵The air flow velocity is high, resulting in significant frictional losses among the components within the flow channel. ⑶Surge occurs, which is extremely harmful to the machine.

Reply to 3# wsm1988: Thanks. I also want to know what the significant differences are in their capacities, and how to choose the appropriate compressor: lol

I suggest you check out the \"Compressed Air Station Design Manual\"; it provides detailed information, and it seems to be available for download on forums.

A centrifugal compressor is a blade-type rotary compressor (i.e., a turbine compressor). In a centrifugal compressor, the high-speed rotating impeller exerts a centrifugal force on the gas, and the diffuser section applies a diffusing effect to the gas, thereby increasing the gas pressure. Advantages include: 1. Centrifugal compressors have a large gas handling capacity, a simple and compact structure, low weight, small unit size, and require less floor space. 　　2. It features balanced operation, reliable performance, high efficiency, and few friction components; as a result, there is a low demand for spare parts, along with reduced maintenance costs and the need for fewer maintenance personnel. 　　3. In chemical processing processes, centrifugal compressors enable the compression of chemical media in a completely oil-free manner. 　　4. The centrifugal compressor is a type of rotary machine that is suitable for being directly driven by industrial steam turbines or gas-fired turbines. In typical large-scale chemical plants, waste steam is commonly used to drive industrial steam turbines for power generation, thereby enabling the comprehensive utilization of thermal energy. However, centrifugal compressors also have some disadvantages. 　　1. Centrifugal compressors are not currently suitable for applications with too low gas flow rates or excessively high pressure ratios. 　　2. The stable operating range of centrifugal compressors is narrow; although gas flow rate adjustment is relatively easy, their economic efficiency is poor. 　　3. Currently, the efficiency of centrifugal compressors is generally lower than that of piston compressors.

Reply to 6# chxp110: I kinda get it now, hehe, thanks:victory:

Not bad, study hard*.................

Working principle: The gas enters from the intake chamber, and the rotating impeller does work on the gas, increasing its pressure, temperature, and velocity. Then the gas moves into the diffuser, where its kinetic energy is converted into pressure energy. The bend/backflow valve primarily serves a guiding function, allowing the gas flow to enter the next stage of the impeller evenly for further compression. As the gas is compressed stage by stage, its temperature continues to rise. To reduce gas temperature and thus minimize energy consumption, after passing through three stages of compression, the gas is led out via a volute; after intermediate cooling, it is then directed to the inlet of the fourth compression stage. The high-pressure gas resulting from six stages of compression is discharged through an outlet pipe. Features of centrifugal compressors: 1. High flow rate. In centrifugal compressors, the gas flows continuously, the flow cross-section is large, and the impeller rotates at high speeds; as a result, the flow rate is very high, with an inlet volume of over 5000 m3/min. 2. High rotational speed. In a centrifugal compressor, the rotor only performs rotational motion; it has a low moment of inertia and does not come into contact with the stationary components. This not only reduces friction but also **increases the rotational speed**. 3. Compact structure. The weight and floor space of the unit are much smaller than those of a piston compressor with the same air volume. 4. Reliable operation. Since there is no direct contact or friction between the rotating components and the stationary components, operation is smooth, exhaust is even, and there are few wear-prone parts; it can generally operate continuously for over a year. There is no need for backup units, and maintenance requirements are low. 5. The single-stage pressure ratio is not high. At present, piston compressors can only be used when the exhaust pressure needs to be above 500105 Pa. 6. Slightly lower efficiency. Due to the high airflow velocity in centrifugal compressors, significant energy loss occurs, resulting in efficiency that is slightly lower than that of piston compressors. 7. Due to the high speed, large power output, and lack of backup units in centrifugal compressors, accidents can have serious consequences; therefore, a range of emergency safety measures are necessary. The approximate flow rate range of gases that can be handled by centrifugal compressors is shown in Table 1-1. The data in the table applies to single-stage compressors; for multi-stage compressors, the minimum displacement is 14.2 m3/min.

There are quite noticeable differences between these two compressors. When making a choice, factors such as operation and maintenance, floor space, stability, and efficiency are relatively less important. The key aspects are processing capacity and discharge pressure, where centrifugal compressors have clear advantages that screw compressors cannot achieve.

Reply to 10# txglfl :victory: Thanks