| dc.description.abstract | At the end of the forties, the integrally geared centrifugal compressor was developed and initially used for air, and later for nitrogen and other gases. To date, about 10,000 units are in use working in the capacity range between 2,000 and 250,000 m³/h. The initial application was limited primarily to the sector of plant air. Within this realm, this compressor concept was not only convincing because of its high degree of efficiency and of its high control range, but, due to lower investment costs with extremely compact design, also compared to single-shaft machines. The logical further development of the integrally geared centrifugal compressor as a process compressor, particularly in its six-stage design, for further process applications such as ammonia plants and the importance of this development for the users of such plants, are detailed. Technical development studies within the framework of a market-orientated machine design have pushed ahead by far the limits of application of geared centrifugal compressors with respect to achievable volumetric flows and pressure ratios, allowable inlet and discharge pressures along with attainable drive speeds. On the one hand, this was achieved due to advances in gear making technology and design leading to extremely compact models of high performance density with logical minimizing of mechanical losses. This type of integrally geared centrifugal compressor can have up to three pinion shafts for receiving up to six impellers. The integration of such compact gearing with standardized low pressure and high pressure compressor stages offers very interesting combination possibilities. For example, those stages with high intake pressure can be used as discharge stages (five and six stage) of an atmospheric intake compressor-discharge pressures up to 50 bar in integrally geared centrifugal compressors, with inlet volume flows of more than 100,000 m³/h can thus be achieved. Conversely, in the case of a four-poster integrally geared centrifugal compressor, which is working with high intake pressure as a recycle compressor in an air separation plant. A low-pressure stage combination intaking from atmosphere with high pressure ratio can be used as the fifth and sixth stages. The feed gas part, whereby, the installation of an additional centrifugal or screw compressor with corresponding high investment costs is not necessary. Within the framework of this description, the design of such integrally geared centrifugal compressors and the corresponding areas of application are to be demonstrated by a few examples from the process industry. In addition to the actual technical design, questions relating to economy and reliability are considered. Further, an overview of the areas of application of six-stage integrally geared centrifugal compressors using gases other than air and nitrogen, i.e., oxygen or hydrcarbon are included. | en |
