Centrifugal machines can be single stage or multi stage. Large volumes of gas are compressed to moderate pressures in centrifugal
- Centrifugal compressors use a rotating disk or impeller in a shaped housing to force the gas to the rim of the impeller, increasing the velocity of the gas.
- A diffuser (divergent duct) section converts the velocity energy to pressure energy.
- They are primarily used for continuous, stationary service in industries such as oil refineries, chemical and petrochemical plants and natural gas processing plants.
- Their application can be from 100 horsepower (75 kW) to thousands of horsepower.
- With multiple staging, they can achieve extremely high output pressures greater than 10,000 psi (69 MPa).
- Many large snowmaking operations (like ski resorts) use this type of compressor.
- They are also used in internal combustion engines as superchargers and turbochargers.
- Centrifugal compressors are used in small gas turbine engines or as the final compression stage of medium sized gas turbines.
- Sometimes the capacity of the compressors is written in NM3/hr. Here ‘N’ stands for normal temperature pressure (20°C and 1 atm ) for example 5500 NM3/hr.
Horizontal Split Case Compressors
- The selection of a single-stage or multistage horizontal split case compressor may depend on the design of the compressor or preference of the nozzle location to suit a particular layout.
- If a grade mounted compressor is planned, the side or top orientation may be selected, whereas the bottom connections are generally used for elevated compressors.
- During maintenance, the top half of the compressor case is removed by lifting it vertically and away from the bottom assembly.
- This configuration is used for chemical, petrochemical, industrial and process air, refrigeration and high-volume and low to medium pressure gas service applications.
- Variations of horizontal split case compressor are shown below.
Vertical Split Case Compressors
- Following figure shows how this application can come with top or bottom orientations on then nozzles.
- Layout preference dictate the selection.
- Removal of the rotor assembly is through the front end of the compressor, away from the driver; the compressor vendor supplies the removal distance to the play layout designer.
- This design is used for catalytic reforming, gas conversion and repressurizing, processing services, refrigeration and high-pressure, low volume or high volume, low pressure gas service applications.
- More than one compressor may be hooked in tandem.