The integrally geared compressor is a multi-shaft centrifugal compressor. The number of stages is determined by the process requirements and the relationship between costs and efficiency. Typical benefits of the various types of integrally geared compressors are high efficiency, low operating costs, a low investment outlay and an excellent operating range. Specific applications include industrial gases, oil & gas, CO2, urea, purified terephthalic acid or nitric acid processes. Additional applications are fuel gas boosters for large scale gas turbines.