Showing papers in "Turbomachinery International in 1992"

Simplified Mathematical Representations of Single Shaft Gas Turbines in Mechanical Drive Service

Abstract: There have been several recent applications of large single shaft, heavy duty gas turbines in mechanical drive service, powering high horsepower, multi-casing compressors. This variable speed application of a traditional constant speed driver, with a more limited operating speed range, has created a need for simplified but accurate mathematical representations that can be incorporated into overall process simulations to allow interactive dynamic evaluation of the complete system.This paper presents simplified mathematical representations of four gas turbines covering the horsepower range from 26,000 HP to 108,000 HP. The models incorporate both the control and fuel system characteristics as well as those of the turbomachinery. Although gas fuel is assumed, listed references can be used to accomodate liquid fuel. The models are suitable for a wide range of ambient temperatures, and the influence of axial flow compressor variable inlet guide vanes is included in the models as appropriate to the actual machinery configuration.Copyright © 1992 by ASME

Developments in fluid film bearing technology

Abstract: Fluid film bearings are available in a variety of configurations. The trend over the last two decades has favored variable geometry tilting pad bearings over fixed geometry sleeve type bearings due to their inherent stability characteristics. However, standard type tilting pad bearings are more complex, contain more parts, and generally have lower damping than fixed geometry bearings. In some instances, a reversal of the trend has been noted by which tilting pad bearings were replaced by fixed geometry sleeve bearings. This shows that standard type tilt pad bearings do not represent a cure to all ailments in turbomachinery bearings. This article describes some problems and drawbacks in the widely used fluid film bearings, and discusses new developments in fluid film bearing technology to address these problems. 5 refs., 17 figs.

Compressor washing on line for large gas turbines

Abstract: In the often polluted atmosphere in which many gas turbines are installed, frequent compressor washing is essential to maintain performance and prevent erosion of blading. Major pollutants include salt for those facilities near the coast and hydrocarbon aerosols for those facilities near motorways and industrial sites. Equipment has been developed for washing large gas turbine compressors on line to arrest the rate of fouling in baseload operation. The design and operation of the equipment is described and the operational flow path is presented. 3 figs.

Advancements in magnetic bearing control systems

Abstract: As an operator of over 20 magnetic bearing systems installed on natural gas pipeline compression equipment, NOVA has become intimately familiar with the challenges posed by wholesale conversion to a new technology. This paper outlines the capabilities of a digitally controlled analog magnetic bearing controller, developed by NOVA, which more fully exploits the diagnostic information available from magnetic bearing signals, and also reduces the time required for control system tuning due to the digital interface. These capabilities address several key issues surrounding magnetic bearing system operation which may be preventing greater industry acceptance of this technology. 4 figs.