Fundamentals of Processing Technology (Question and Answer) 20171105
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What are the advantages and disadvantages of centrifugal compressors?
The advantages of centrifugal compressors are: (1) they have a compact structure and small size, which means that the floor space required and the weight of such compressors are much less compared to piston compressors with the same air handling capacity； (2) It operates smoothly, is reliable in operation, and requires few spare parts; as a result, it has a high operational efficiency along with lower maintenance costs and fewer staff needed ； (3) The compression process of centrifugal compressors can be carried out completely oil-free, which is very important for chemical production ； (4) A centrifugal compressor is a machine that performs rotational motion; it operates at high speeds, so it is suitable to be directly driven by an industrial steam turbine or gas turbine. The disadvantages are: (1) Centrifugal compressors are not yet suitable for applications with too low gas flow rates and 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 still lower than that of piston compressors.
The advantages of centrifugal compressors are: (1) they have a compact structure and small size, which means that the floor space required and the weight of such compressors are much less compared to piston compressors with the same air handling capacity； (2) It operates smoothly, is reliable in operation, and requires few spare parts; as a result, it has a high operational efficiency along with lower maintenance costs and fewer staff needed ； (3) The compression process of centrifugal compressors can be carried out completely oil-free, which is very important for chemical production ； (4) A centrifugal compressor is a machine that performs rotational motion; it operates at high speeds, so it is suitable to be directly driven by an industrial steam turbine or gas turbine. The disadvantages are: (1) Centrifugal compressors are not yet suitable for applications with too low gas flow rates and 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 still lower than that of piston compressors.
The advantages of centrifugal compressors are: (1) they have a compact structure and small size, which means that the floor space required and the weight of such compressors are much less compared to piston compressors with the same air handling capacity； (2) It operates smoothly, is reliable in operation, and requires few spare parts; as a result, it has a high operational efficiency along with lower maintenance costs and fewer staff needed ； (3) The compression process of centrifugal compressors can be carried out completely oil-free, which is very important for chemical production ； (4) A centrifugal compressor is a machine that performs rotational motion; it operates at high speeds, so it is suitable to be directly driven by an industrial steam turbine or gas turbine. The disadvantages are: (1) Centrifugal compressors are not yet suitable for applications with too low gas flow rates and 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 still lower than that of piston compressors.
Main advantages: large and continuous gas flow, stable operation； The unit has a small size, light weight, and requires little floor space ； It has few vulnerable components, a long service life, and requires minimal maintenance ； Due to the high rotational speed, it can be driven directly by a turbine, which is relatively safe and facilitates automatic control. Main drawback: Lower efficiency compared to axial flow compressors and reciprocating compressors ； The stable operating range is relatively narrow, and surge occurs.
The advantages of centrifugal compressors are: (1) they have a compact structure and small size, which means that the floor space required and the weight of such compressors are much less compared to piston compressors with the same air handling capacity； (2) It operates smoothly, is reliable in operation, and requires few spare parts; as a result, it has a high operational efficiency along with lower maintenance costs and fewer staff needed ； (3) The compression process of centrifugal compressors can be carried out completely oil-free, which is very important for chemical production ； (4) A centrifugal compressor is a machine that performs rotational motion; it operates at high speeds, so it is suitable to be directly driven by an industrial steam turbine or gas turbine. The disadvantages are: (1) Centrifugal compressors are not yet suitable for applications with too low gas flow rates and 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 still lower than that of piston compressors.
Advantages: 1. Under the same cooling capacity, especially at high capacities, compared to reciprocating compressor units, it eliminates the need for a large oil separation system, resulting in less weight and size for the unit as well as reduced floor space required. 2. The centrifugal compressor has a simple and compact structure, with few moving parts; it operates reliably, is durable, and has low operating costs. 3. Multi-stage compression and various evaporation temperatures can be easily achieved, as well as intermediate cooling, with lower energy consumption. 4. Very little lubricating oil is mixed into the centrifugal compressor, which has little impact on the heat transfer efficiency of the heat exchangers, allowing the unit to achieve high efficiency. Disadvantages: 1. The rotor rotates at high speeds; to maintain a certain width for the impeller, centrifugal compressors must be used in applications with medium to high flow rates, and they are not suitable for low-flow applications. 2. The pressure ratio per stage is low, so multi-stage impellers are required to achieve higher pressure ratios, and speed increase gears are usually also needed. 3. Surge is an inherent drawback of centrifugal compressors, necessitating the use of anti-surge systems. 4. The operating conditions of a centrifugal compressor cannot vary greatly, limiting its range of applicable applications.
The advantages of centrifugal compressors are: (1) they have a compact structure and small size, which means that the floor space required and the weight of such compressors are much less compared to piston compressors with the same air handling capacity； (2) It operates smoothly, is reliable in operation, and requires few spare parts; as a result, it has a high operational efficiency along with lower maintenance costs and fewer staff needed ； (3) The compression process of centrifugal compressors can be carried out completely oil-free, which is very important for chemical production ； (4) A centrifugal compressor is a machine that performs rotational motion; it operates at high speeds, so it is suitable to be directly driven by an industrial steam turbine or gas turbine. The disadvantages are: (1) Centrifugal compressors are not yet suitable for applications with too low gas flow rates and 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 still lower than that of piston compressors.
Advantages:
At the same cooling capacity, especially for large capacities, compared to reciprocating compressor units, it eliminates the need for a large oil separation system. As a result, the unit has less weight and size, requiring less floor space.
Centrifugal compressors have a simple and compact structure, with few moving parts. They operate reliably, are durable, and have low operating costs.
Multi-stage compression and various evaporation temperatures can be easily achieved, as well as intermediate cooling, resulting in lower energy consumption.
Very little lubricating oil enters the centrifugal compressor, which minimizes the impact on the heat transfer efficiency of the heat exchangers, thus enabling higher efficiency.
It is possible to make use of various heat recovery systems in the factory to optimize the utilization of thermal energy, thereby improving the overall thermal efficiency of the production process, saving on capital investment, and reducing product costs.
The structure is simple, with few vulnerable components, making maintenance easy. Reliable operation is achieved without the need for backup units.
They operate at high speeds, provide uniform gas supply, require less floor space, and involve lower investment costs.
The problem of gases containing oil is eliminated.
Application range: Suitable for applications with medium to high flow rates and medium to low pressures.
They require less floor space, have a simple structure, light weight, high gas delivery capacity, no need for backup units, and low equipment investment costs.
Centrifugal compressors are driven by steam, which facilitates the efficient utilization of by-produced steam and reduces energy consumption.
They have few vulnerable components, operate stably, and have low operating costs.
Gas delivery is uniform, and adjustment is easy; automated control is possible.
No lubricating oil needs to be injected into the cylinder.
Disadvantages:
The rotor rotates at high speeds. To maintain a certain width of the impeller, centrifugal compressors must be used in applications with medium to high flow rates; they are not suitable for low-flow applications.
The pressure ratio per stage is low. To achieve a higher pressure ratio, multiple stages of impellers are required, along with speed increase gears.
Surge is an inherent drawback of centrifugal compressors, necessitating the use of surge prevention systems.
The operating conditions of a centrifugal compressor cannot vary greatly, limiting its application range.
The efficiency of centrifugal compressors is 5%–10% lower than that of piston compressors.
They can only achieve maximum efficiency under their designed operating conditions, and they are prone to surge.
Centrifugal compressors cannot produce low flow rates while maintaining high pressure ratios.
Their operational flexibility is limited; high gas flow rates lead to high frictional losses and lower efficiency, as well as surge problems.
Well-designed medium and large-sized piston compressors have an efficiency of over 75%, while centrifugal compressors usually have an efficiency below 70%.
The exhaust pressure changes with the flow rate.
They are not resistant to impurities and liquid droplets.
Due to technical and manufacturing constraints, their cost is high, and delivery times are long.
The temperature at the compression outlet is relatively high, requiring a large heat exchange area.
The pressure ratio per stage is low, rarely exceeding 3.
Due to losses associated with high-speed gas flow, the efficiency of centrifugal compressors is lower than that of reciprocating compressors.
They are suitable for applications with large volumes of gas.
They have high requirements regarding the compressed medium.
They are susceptible to changes in the temperature, pressure, and composition of the compressed medium
At the same cooling capacity, especially for large capacities, compared to reciprocating compressor units, it eliminates the need for a large oil separation system. As a result, the unit has less weight and size, requiring less floor space.
Centrifugal compressors have a simple and compact structure, with few moving parts. They operate reliably, are durable, and have low operating costs.
Multi-stage compression and various evaporation temperatures can be easily achieved, as well as intermediate cooling, resulting in lower energy consumption.
Very little lubricating oil enters the centrifugal compressor, which minimizes the impact on the heat transfer efficiency of the heat exchangers, thus enabling higher efficiency.
It is possible to make use of various heat recovery systems in the factory to optimize the utilization of thermal energy, thereby improving the overall thermal efficiency of the production process, saving on capital investment, and reducing product costs.
The structure is simple, with few vulnerable components, making maintenance easy. Reliable operation is achieved without the need for backup units.
They operate at high speeds, provide uniform gas supply, require less floor space, and involve lower investment costs.
The problem of gases containing oil is eliminated.
Application range: Suitable for applications with medium to high flow rates and medium to low pressures.
They require less floor space, have a simple structure, light weight, high gas delivery capacity, no need for backup units, and low equipment investment costs.
Centrifugal compressors are driven by steam, which facilitates the efficient utilization of by-produced steam and reduces energy consumption.
They have few vulnerable components, operate stably, and have low operating costs.
Gas delivery is uniform, and adjustment is easy; automated control is possible.
No lubricating oil needs to be injected into the cylinder.
Disadvantages:
The rotor rotates at high speeds. To maintain a certain width of the impeller, centrifugal compressors must be used in applications with medium to high flow rates; they are not suitable for low-flow applications.
The pressure ratio per stage is low. To achieve a higher pressure ratio, multiple stages of impellers are required, along with speed increase gears.
Surge is an inherent drawback of centrifugal compressors, necessitating the use of surge prevention systems.
The operating conditions of a centrifugal compressor cannot vary greatly, limiting its application range.
The efficiency of centrifugal compressors is 5%–10% lower than that of piston compressors.
They can only achieve maximum efficiency under their designed operating conditions, and they are prone to surge.
Centrifugal compressors cannot produce low flow rates while maintaining high pressure ratios.
Their operational flexibility is limited; high gas flow rates lead to high frictional losses and lower efficiency, as well as surge problems.
Well-designed medium and large-sized piston compressors have an efficiency of over 75%, while centrifugal compressors usually have an efficiency below 70%.
The exhaust pressure changes with the flow rate.
They are not resistant to impurities and liquid droplets.
Due to technical and manufacturing constraints, their cost is high, and delivery times are long.
The temperature at the compression outlet is relatively high, requiring a large heat exchange area.
The pressure ratio per stage is low, rarely exceeding 3.
Due to losses associated with high-speed gas flow, the efficiency of centrifugal compressors is lower than that of reciprocating compressors.
They are suitable for applications with large volumes of gas.
They have high requirements regarding the compressed medium.
They are susceptible to changes in the temperature, pressure, and composition of the compressed medium
The advantages of centrifugal compressors are: (1) they have a compact structure and small size, which means that the floor space required and the weight of such compressors are much less compared to piston compressors with the same air handling capacity； (2) It operates smoothly, is reliable in operation, and requires few spare parts; as a result, it has a high operational efficiency along with lower maintenance costs and fewer staff needed ； (3) The compression process of centrifugal compressors can be carried out completely oil-free, which is very important for chemical production ； (4) A centrifugal compressor is a machine that performs rotational motion; it operates at high speeds, so it is suitable to be directly driven by an industrial steam turbine or gas turbine. The disadvantages are: (1) Centrifugal compressors are not yet suitable for applications with too low gas flow rates and 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 still lower than that of piston compressors.