Advantages of centrifugal compressors

Agreed, but it also has disadvantages: lower efficiency, the capacity of a single unit must be large, poor adaptability to changing operating conditions, and high noise levels. Last edited by lalalazhou on 2009-2-28 10:30.]

Compared with piston compressors, centrifugal compressors, especially those driven by steam turbines, have the following advantages: 1. High production capacity, uniform gas supply, compact structure, small floor area, and low civil engineering costs. 2. It has a simple structure, few vulnerable components, is easy to maintain, operates reliably, and has a long continuous operation cycle – it can generally operate continuously for 1 to 2 years or more; therefore, no backup unit is required. The manpower and resources required for operation and maintenance are much less than those of piston compressors. 3. Between the rotor and the stator, there is no part with contact friction aside from the bearings and shaft end seals; therefore, no lubricating oil needs to be added inside the cylinder. This eliminates the problem of oil being carried by the gas, which is beneficial for chemical reactions and increases the synthesis rate, thereby extending the lifespan of the catalyst. This is particularly suitable for compressing gases that must not come into contact with oil, such as oxygen. 4. Centrifugal compressors are high-speed rotating machines, suitable for direct drive by steam turbines or gas turbines. For large petrochemical plants, steam or flue gas is generated as a by-product during the production process. If a turbine that uses these by-products as energy directly drives a centrifugal compressor, the overall thermal efficiency in the production process can be improved, thereby saving on capital investment in power generation and reducing product costs. 5. For centrifugal compressors and turbine units with the same capacity, their cost is much lower than that of piston compressors and motors, thus reducing the construction costs. Although centrifugal compressors have the advantages mentioned above, they also have the following disadvantages. 1. The efficiency of centrifugal compressors is generally lower than that of piston compressors, as the air flow velocity in centrifugal compressors is higher, resulting in greater energy losses. 2. Centrifugal compressors can achieve their highest efficiency only when operating under their designed conditions; efficiency drops when they are operated away from these conditions. More significantly, when the flow rate decreases to a certain level, the compressor may experience surge, and if this is not addressed promptly, it can lead to damage to the machine. Piston compressors do not exhibit this phenomenon. 3. Centrifugal compressors cannot easily achieve a low flow rate while maintaining a high pressure ratio. The single-stage pressure ratio of centrifugal compressors rarely exceeds 3. In piston compressors, the pressure ratio per stage can reach 2 to 4 or more. For centrifugal compressors with high pressure ratios and low flow rates, the narrow airflow channels resulting from the low flow rate make manufacturing difficult, lead to high flow losses, and reduce the compressor’s efficiency.

The outlet pressure of the centrifuge is proportional to the molecular weight of the medium; therefore, when the composition of the medium changes, the outlet pressure of the centrifuge may vary and may not even meet the process requirements. Raising the molecular weight is the only way to address the issue of insufficient outlet pressure, and this point should be kept in mind. Reciprocating machines, on the other hand, are independent of the molecular weight of the medium.

Relatively inexpensive; however, due to the costs associated with transporting the materials and the operating conditions, other options have to be chosen