Abstract:
Systems for shielding a shaft from contaminants are disclosed. In one embodiment, a contaminant shield system for a shaft includes: a fluid seal disposed circumferentially about the shaft, the fluid seal substantially fluidly isolating an inner portion of the shaft from atmospheric air; an oil deflector ring disposed circumferentially about the inner portion of the shaft, the oil deflector ring having an inner surface facing a portion of the shaft exposed to a lubricating oil and an outer surface facing the fluid seal; and a fluid conduit interposed between the fluid seal and the outer surface of the oil deflector ring, the fluid conduit for receiving a fluid and releasing the fluid between the fluid seal and the outer surface of the oil deflector ring creating a positive pressure differential.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The subject matter disclosed herein relates to rotating shafts and, more particularly, to a system for shielding a rotating shaft environment from contaminants. 
         [0002]    Some power plant systems, for example certain nuclear, simple cycle and combined cycle power plant systems, employ journal bearings along rotating shafts in their design and operation. These journal bearings are provided with a flow of lubricating oil which is contained from axial leakage by an oil deflector system. These oil deflector systems generally include oil deflector rings which are disposed in close proximity to the shaft and act as barriers to the lubricating oil. During operation, contaminants become deposited on the radial surface of these rings. These depositions produce friction with the shaft, rotor stator rubs, and coking, which lead to work stoppages and shorten the life of the shaft. Therefore, it is desirable to eliminate or limit the deposition of contaminants on the surface of the oil deflector rings. Some power plant systems limit contaminant deposition by blowing air between the outer oil deflector rings and the shaft, blowing contaminants off of and away from the lubricating oil and oil deflector rings. These systems fail to prevent contaminants from depositing on the outermost oil deflector rings which are still exposed to atmospheric air and the contaminants therein which are detrimental to the system. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0003]    Systems for shielding contaminants from a rotating shaft are disclosed. In one embodiment, a contaminant shield system for a shaft includes: a fluid seal disposed circumferentially about the shaft, the fluid seal substantially fluidly isolating an inner portion of the shaft from atmospheric air; an oil deflector ring disposed circumferentially about the inner portion of the shaft, the oil deflector ring having an inner surface facing a portion of the shaft exposed to a lubricating oil and an outer surface facing the fluid seal; and a fluid conduit interposed between the fluid seal and the outer surface of the oil deflector ring, the fluid conduit for receiving a fluid and releasing the fluid between the fluid seal and the outer surface of the oil deflector ring creating a positive pressure differential. 
         [0004]    A first aspect of the disclosure provides a contaminant shield system for a shaft including: a fluid seal disposed circumferentially about the shaft, the fluid seal substantially fluidly isolating an inner portion of the shaft from atmospheric air; an oil deflector ring disposed circumferentially about the inner portion of the shaft, the oil deflector ring having an inner surface facing a portion of the shaft exposed to a lubricating oil and an outer surface facing the fluid seal; and a fluid conduit interposed between the fluid seal and the outer surface of the oil deflector ring, the fluid conduit for receiving a fluid and releasing the fluid between the fluid seal and the outer surface of the oil deflector ring creating a positive pressure differential. 
         [0005]    A second aspect provides a power generation system including: a turbine, the turbine including a shaft; a generator operatively connected to the turbine; a fluid seal disposed circumferentially about the shaft, the fluid seal substantially fluidly isolating an inner portion of the shaft from atmospheric air; an oil deflector ring disposed circumferentially about the inner portion of the shaft, the oil deflector ring having an inner surface facing a portion of the shaft exposed to a lubricating oil and an outer surface facing the fluid seal; and a fluid conduit interposed between the fluid seal and the outer surface of the oil deflector ring, the fluid conduit for receiving a fluid and releasing the fluid between the fluid seal and the outer surface of the oil deflector ring creating a positive pressure differential. 
         [0006]    A third aspect provides a combined cycle power generation system comprising: a gas turbine, the gas turbine including a shaft; a heat recovery steam generator (HRSG) operatively connected to the gas turbine; a steam turbine operatively connected to the HRSG, the steam turbine including a shaft; a generator operatively connected to at least one of the gas turbine or the steam turbine; a fluid seal disposed circumferentially about at least one of the gas turbine shaft or the steam turbine shaft, the fluid seal substantially fluidly isolating an inner portion of the shaft from atmospheric air; an oil deflector ring disposed circumferentially about the inner portion of the shaft, the oil deflector ring having an inner surface facing a portion of the shaft exposed to a lubricating oil and an outer surface facing the fluid seal; and a fluid conduit interposed between the fluid seal and the outer surface of the oil deflector ring, the fluid conduit for receiving a fluid and releasing the fluid between the fluid seal and the outer surface of the oil deflector ring creating a positive pressure differential. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    These and other features of this invention will be more readily understood from the following detailed description of the various aspects of the invention taken in conjunction with the accompanying drawings that depict various embodiments of the invention, in which: 
           [0008]      FIG. 1  shows a three-dimensional partial cut-away of an embodiment of a contaminant shield system in accordance with an aspect of the invention; 
           [0009]      FIG. 2  shows an end-view, including a partial cut-away, of a portion of a contaminant shield system in accordance with an aspect of the invention; 
           [0010]      FIG. 3  shows a three-dimensional partial cut-away of an embodiment of a contaminant shield system in accordance with an aspect of the invention; 
           [0011]      FIG. 4  shows a three-dimensional partial cut-away schematic view of an embodiment of a contaminant shield system in accordance with an aspect of the invention; 
           [0012]      FIG. 5  shows a three-dimensional partial cut-away schematic view of an embodiment of a contaminant shield system in accordance with an aspect of the invention; 
           [0013]      FIG. 6  shows a partial cut-away schematic view of an embodiment of a contaminant shield system in accordance with an aspect of the invention; 
           [0014]      FIG. 7  shows a partial cut-away schematic view of an embodiment of a contaminant shield system in accordance with an aspect of the invention; 
           [0015]      FIG. 8  shows a partial cut-away schematic view of an embodiment of a contaminant shield system in accordance with an aspect of the invention; 
           [0016]      FIG. 9  shows a partial cut-away schematic view of an embodiment of a contaminant shield system in accordance with an aspect of the invention; 
           [0017]      FIG. 10  shows a schematic view of portions of a multi-shaft combined cycle power plant in accordance with an aspect of the invention; 
           [0018]      FIG. 11  shows a schematic view of a single shaft combined cycle power plant in accordance with an aspect of the invention. 
       
    
    
       [0019]    It is noted that the drawings of the disclosure are not to scale. The drawings are intended to depict only typical aspects of the disclosure, and therefore should not be considered as limiting the scope of the disclosure. In the drawings, like numbering represents like elements between the drawings. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0020]    As indicated above, aspects of the invention provide for systems configured to shield a shaft and oil deflector system from contaminant deposition by using a fluid conduit to control a pressure differential between a fluid seal, which prevents leakage of fluids (i.e. steam) to the atmosphere using a low pressure vent, and an outer surface of an outermost oil ring deflector. The fluid conduit supplies a pressurized fluid to the cavity between the fluid seal and the outer surface of the outermost oil ring, thereby creating a positive pressure differential between the cavity and the atmosphere outside of the fluid seal and preventing contaminants and atmospheric air from entering the cavity. 
         [0021]    In the art of power generation systems (including, e.g., nuclear reactors, steam turbines, gas turbines, etc.), rotating shafts with lubricated journal bearings are often employed as part of the system and may include an oil deflector system. Typically, the oil deflector system employs multiple sets of oil deflector rings to prevent against axial oil leakage and contaminants entering the journal bearings. The multiple sets of oil deflector rings are designed as a labyrinth seal, located circumferentially about the shaft with a working clearance between the shaft and oil deflector rings. However, the working clearance between the oil deflector rings and shaft enable some of the lubricating oil to leak out axially and for some contaminants to enter the system. This leakage of the lubricating oil and entrance of contaminants may result in contaminants building up on the oil deflector rings and entering the bearing system via the lubricating oil. This buildup and oil contamination can cause rotor-stator rubbing, poor bearing performance, coking and shortened system life. A higher average-contaminate level on the oil deflector rings and in the journal bearings detracts from the overall efficiency of the power generation system by causing large frictional, thermal and equipment maintenance losses. 
         [0022]    Turning to the figures, embodiments of a shaft and a contaminant shield system including a fluid conduit are shown, where the contaminant shield system may increase efficiency and life expectancy of the journal bearings, the shaft and the overall power generation system by reducing the amount of contaminants which come into contact with the lubricating oil and by reducing the deposition of contaminants upon the oil deflector rings. Each of the components in the figures may be connected via conventional means, e.g., via a common conduit or other known means as is indicated in  FIGS. 1-11 . Specifically, referring to  FIG. 1 , a three-dimensional partial cut-away of an embodiment of a contaminant shield system  100  is shown. Contaminant shield system  100  may include a shaft  110 , a fluid seal  120 , an oil deflector housing  130 , at least one oil deflector ring  140  and a fluid conduit  150 . Contaminant shield system  100  may receive a fluid from a fluid source  154  via fluid conduit  150 , where fluid conduit  150  may be any conventional conduit for conveying fluid to contaminant shield system  100 . Fluid conduit  150  may convey the fluid into a shield cavity  192  positioned between fluid seal  120  and oil deflector housing  130 , thereby creating a positive pressure differential relative to atmospheric pressure on fluid seal  120 . Delivery and manner of delivery of the fluid may be accomplished in any number of ways as discussed further below. 
         [0023]    In an embodiment of the present invention, contaminant shield system  100  includes a plurality of oil deflector rings  140  which may be disposed circumferentially about shaft  110  to seal an inner portion  111  of shaft  110  from atmospheric exposure. It is understood that inner portion  111  may be in fluid communication with journal bearings as is common in the art. The plurality of oil deflector rings  140  may be conventional oil deflector rings known in the art. In one embodiment, oil deflector housing  130  of contaminant shield system  100  may be fluidly connected to a bearing housing  132 . In one embodiment, contaminant shield system  100  may include a clearance shield  124  (shown in phantom) which may be at least partially interposed between fluid seal  120  and shaft  110 . Clearance shield  124  may create a reduced working tolerance between shaft  110  and fluid seal  120 , where the reduced working tolerance will minimize the entrance area for atmospheric air and increase the positive pressure differential. In one embodiment, fluid conduit  150  is comprised of a single conduit which may be oriented substantially circumferentially about shaft  110 . In another embodiment, contaminant shield system  100  includes a plurality of fluid conduits  150  which may be disposed between fluid seal  120  and oil deflector housing  130 . The plurality of fluid conduits  150  may be oriented substantially circumferentially about shaft  110  and may convey fluids to the contaminant shield system  100 . 
         [0024]    Turning to  FIG. 2 , a schematic partial cut-away of an end-view of a contaminant shield system  200  is shown according to embodiments. It is understood that elements similarly numbered between  FIG. 1  and  FIG. 2  may be substantially similar as described with reference to  FIG. 1 . Further, in embodiments shown and described with reference to  FIGS. 2-11 , like numbering may represent like elements. Redundant explanation of these elements has been omitted for clarity. Finally, it is understood that the components of  FIGS. 1-11  and their accompanying descriptions may be applied to any embodiment described herein. Returning to  FIG. 2 , in this embodiment, contaminant shield system  200  may include a plurality of fluid conduits  150  which may be disposed circumferentially about shaft  110 . In this embodiment, the plurality of fluid conduits  150  may convey fluid into the contaminant shield system  100  between fluid seal  120  and oil deflector housing  130 . In one embodiment, plurality of fluid conduits  150  may receive the fluid from a common conduit  202 . 
         [0025]    Turning to  FIG. 3 , a three-dimensional partial cut-away of an alternate embodiment of a contaminant shield system  300  is shown having at least one fluid conduit  150  located in fluid communication with oil deflector housing  130 . In this embodiment, at least one fluid conduit  150  may be formed within oil deflector housing  130 , with the at least one fluid conduit  150  being configured to receive a fluid from fluid source  154  and convey the fluid to shield cavity  192  between oil deflector housing  130  and the fluid seal  120 , thereby creating a positive pressure differential in shield cavity  192 . 
         [0026]    Turning to  FIG. 4 , a three-dimensional partial cut-away schematic view of an embodiment of a contaminant shield system  400  is shown according to embodiments of the invention having a plurality of fluid conduits  150  machined into oil deflector housing  130 . The plurality of fluid conduits  150  may be configured to convey a fluid toward fluid seal  120  into shield cavity  192  creating a positive pressure differential. In one embodiment, the fluid being conveyed by the plurality of fluid conduits  150  may be filtered air. 
         [0027]    Turning to  FIG. 5 , a three-dimensional perspective view of a partial cross-sectional of contaminant shield system  500  according to embodiments of the invention is shown having at least one fluid conduit  150  fluidly connected to oil deflector housing  130 . The at least one fluid conduit  150  may be configured to convey a fluid into shield cavity  192  between oil deflector housing  130  and fluid seal  120 , creating a positive pressure differential. In one embodiment, at least one fluid conduit  150  may include a fluid seal shield  522  interposed between the at least one fluid conduit  150  and fluid seal  120 . In one embodiment, fluid seal shield  522  may extend radially inwardly toward shaft  110  from at least one fluid conduit  150 , creating an oil deflector cavity  524  defined by fluid seal shield  522 , shaft  110  and oil deflector housing  130 . The fluid conduit  150  may release a portion of the fluid into the oil deflector cavity  524  creating a positive pressure differential in oil deflector cavity  524 . In one embodiment, fluid seal shield  522  may also extend axially, further defining oil deflector cavity  524 . 
         [0028]    Turning to  FIG. 6 , a partial cut-away schematic view of an alternate embodiment of a contaminant shield system  600  is shown having a fluid seal shield  522  fluidly connected to oil deflector housing  130  which has a plurality of fluid conduits  150  machined into it. The plurality of fluid conduits  150  may be configured to convey a fluid away from oil deflector housing  130  into an oil deflector cavity  524  defined by shaft  110 , oil deflector housing  130  and fluid seal shield  522 , creating a positive pressure differential in oil deflector cavity  524 . 
         [0029]    Turning to  FIG. 7 , a partial cut-away schematic view of an embodiment of contaminant shield system  700  is shown having at least one fluid conduit  150  fluidly connected to fluid seal  120 . The at least one fluid conduit  150  may be configured to convey a fluid into shield cavity  192  between oil deflector housing  130  and fluid seal  120 , creating a positive pressure differential. In one embodiment, contaminant shield system  100  may include a fluid seal shield  722  interposed between the at least one fluid conduit  150  and oil deflector housing  130 . In one embodiment, fluid seal shield  722  may extend radially inwardly toward shaft  110  from at least one fluid conduit  150 , creating a fluid seal cavity  724  defined by fluid seal  120 , shaft  110  and fluid seal shield  722 . The fluid conduit  150  may release a portion of the fluid into fluid seal cavity  724  creating a positive pressure differential in fluid seal cavity  724 . 
         [0030]    Turning to  FIG. 8 , a partial cut-away schematic view of an embodiment of a contaminant shield system  800  is shown having at least one fluid conduit  150  fluidly connected to the fluid seal  120 . The contaminant shield system  100  includes a fluid seal shield  722  interposed between the at least one fluid conduit  150  and oil deflector housing  130 . Fluid seal shield  722  may extend radially inwardly toward shaft  110  from at least one fluid conduit  150  and all or portions of fluid seal shield  722  may also extend axially, further defining fluid seal cavity  724 . Fluid conduit  150  may release a portion of the fluid into fluid seal cavity  724  creating a positive pressure differential. In one embodiment of the present invention, an axially extended portion  823  of fluid seal shield  722  is positioned at an angle “a” relative to shaft  110  so as to decrease the size of opening  828  into shield cavity  192 , where this decreased size of opening  828 , among other things, increases the positive pressure differential. In another embodiment of the present invention, the angle “a” of axially extended portion  823  of fluid seal shield  722  relative to shaft  110  is adjustable across a range. 
         [0031]    Turning to  FIG. 9 , a partial cut-away schematic view of an embodiment of a contaminant shield system  900  is shown having at least one fluid conduit  150  fluidly connected to fluid seal  120 . The at least one fluid conduit  150  being configured at an angle toward fluid seal  120  such that fluid is directed toward fluid seal  120 . 
         [0032]    Turning to  FIG. 10 , a schematic view of portions of a multi-shaft combined cycle power plant  910  is shown. Combined cycle power plant  910  may include, for example, a gas turbine  942  operably connected to a generator  944 . Generator  944  and gas turbine  942  may be mechanically coupled by a shaft  911 , which may transfer energy between a drive shaft (not shown) of gas turbine  942  and generator  944 . Shaft  911  may be fluidly connected to contaminant shield system  100  of  FIG. 1  or other embodiments described herein. Also shown in  FIG. 9  is a heat exchanger  946  operably connected to gas turbine  942  and a steam turbine  948 . Heat exchanger  946  may be fluidly connected to both gas turbine  942  and a steam turbine  948  via conventional conduits (numbering omitted). Heat exchanger  946  may be a conventional heat recovery steam generator (HRSG), such as those used in conventional combined cycle power systems. As is known in the art of power generation, HRSG  946  may use hot exhaust from gas turbine  942 , combined with a water supply, to create steam which is fed to steam turbine  948 . Steam turbine  948  may optionally be coupled to a second generator system  944  (via a second shaft  911 ). It is understood that generators  944  and shafts  911  may be of any size or type known in the art and may differ depending upon their application or the system to which they are connected. Common numbering of the generators and shafts is for clarity and does not necessarily suggest these generators or shafts are identical. Generator system  944  and second shaft  911  may operate substantially similarly to generator system  944  and shaft  911  described above. In one embodiment of the present invention (shown in phantom), contaminant shield system  100  receives a fluid from a fluid source  154 . Fluid source  154  may be fluidly connected to fluid conduit  150 . Fluid source  154  may be a compressor, pressurized gas source or other fluid source as is known in the art. In another embodiment (shown in phantom), contaminant shield system  100  may receive a fluid via fluid conduit  150  in the form of compressed air generated from the operation of gas turbine  942 . In another embodiment, steam turbine  946  may include at least one shaft  911  which is fluidly connected to contaminant shield system  100 . In another embodiment gas turbine  942  may include at least one shaft  911  which is fluidly connected to contaminant shield system  100 . In another embodiment, shown in  FIG. 11 , a single shaft combined cycle power plant  990  may include a single generator  944  coupled to both gas turbine  942  and steam turbine  946  via a single shaft  911 . Shaft  911  may be fluidly connected to contaminant shield system  100  of  FIG. 1  or other embodiments  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800  or  900  described herein. 
         [0033]    The contaminant shield system of the present disclosure is not limited to any one particular generator, power generation system or other system, and may be used with other power generation systems and/or systems (e.g., combined cycle, simple cycle, nuclear reactor, etc.). Additionally, the contaminant shield system of the present invention may be used with other systems not described herein that may benefit from the separation and protection of the contaminant shield system described herein. 
         [0034]    The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
         [0035]    This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.