Browsing by Author "Makay, Elemer"

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    Changes In Hydraulic Component Geometries Greatly Increased Power Plant Availability And Reduced Maintenance Costs: Case Histories
    (Turbomachinery Laboratories, Department of Mechanical Engineering, Texas A&M University, 1984) Makay, Elemer; Barrett, James A.; International Pump Users Symposium (1st : 1984)
    A systematic investigation was started within the Texas Utilities Generating Company Power station feedwater pump systems due to unsatisfactory unit availability, frequent equipment breakdown, high maintenance costs, and high replacement parts costs. This action was greatly encouraged by successful corrective actions taken by other utilities [1,2,3], results of failure surveys across the U.S.A [4,5), and systematic long range research and development, field testing and troubleshooting by the authors, and close cooperation and exchange of ideas and results with at least on oil company [6]. A total of 36 pumps was modified in the Texas Utilities system as described in this paper. This included 16 boiler feed pumps (BFP), 7 high pressure (HP) booster pumps, 6 low pressure (LP) booster pumps, and 7 other pump applications. The operating behavior of all pumps improved exactly as expected, with the exception of one high pressure booster pump, which is described as a special case, with the emphasis on the importance or re-assembly and maintenance procedures. The power plants and the type of pumps involved in this investigation and corrective design changes are reflected in Table1. Basically, we have to distinguish between multistage boiler feed pumps (or process pumps) and single stage double suction booster pumps (or condensate, ash sluice, circulating, cooling water, etc) because the same hydraulically induced instability problem manifests itself in a very different way through the type of vibrations we experience and measure. Single stage pumps usually show a herby axial vibration mode of the rotor, while multistage pumps show radial response, although the origin of the excitation is the same.
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    Problems Encountered In Boiler Feed Pump Operation
    (Texas A&M University. Gas Turbine Laboratories, 1976) Makay, Elemer; Turbomachinery Symposium (5th : 1976)
    Although mechanical and hydraulic instabilities in centrifugal pumps caused a considerable amount of problems for large Nuclear and Fossil Generating Stations influencing "Power Plant Availability," a relatively limited amount of res Parch work was clone in this area. The author makes an attempt to outline problems in general, gives definitions for hydraulic and dynamic "Instabilities," outlines the "Mechanisms" that create them, establishes safe operating speed and flow ranges for large pumps, and discusses how to treat the above subjects when Held failures occurred. Interaction between hydraulically induced forces and bearing design parameters, and their influence on rotor vibration characteristics is emphasized. Friction induced partial frequency modes are also discussed. These forces are sizable and can influence rotor and bearing design requirements, can change rotor stability and the appearance of the pump rotor critical speeds. Comparison is made between vertically and horizontally oriented pumps and between volute and diffuser types. The author also outlines the minimum instrumentation necessary to identify problem areas before and after failure occurs and supports this with actual field failure cases. It is outlined how a simple factory (witness) test can uncover potential future Held problems. Areas where systematic future research and development work is necessary are pointed out.