High Speed Oil-Free Turbomachinery String.
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This paper is a discussion of the design, manufacture, test, and field operation of a totally oil-free string of rotating equipment. The turbomachinery string consists of a multistage centrifugal compressor driven by a single valve multistage steam turbine. The steam turbine is rated at 1837 kW (2463 hp) with a maximum continuous speed of 9734 rpm. The string is currently operating in propane refrigeration service at a petrochemical complex in Saudi Arabia. Both the steam turbine and the compressor have magnetic journal and thrust bearings, dry gas face seals to contain the process gas in the compressor, and pneumatic/electronic actuators control the steam flow through the steam turbine while providing trip protection. The design of the compressor, steam turbine, associated components, and the control theory required by the magnetic bearings are reviewed and discussed in detail. The development of the theoretical rotordynarnic simulation for magnetic bearings is presented and the results are compared with actual operating conditions. Special consideration is given to the coastdown case where the rotors are delevitated onto the auxiliary bearings. Shop testing and control system tuning of the assembled turbomachinery string along with field operating experience are reviewed. · Finally, the trouble spots encountered during the design, manufacture, testing, installation, and field operation of this oilfree string are discussed and suggestions are made in order to avoid these problems in the future.
Safwani, Ali H. Al; Dechoudhury, Pranabesh; Garvey, Martin; Farabaugh, Chet (1998). High Speed Oil-Free Turbomachinery String.. Texas A&M University. Turbomachinery Laboratories. Available electronically from