Patent Publication Number: US-8529198-B2

Title: External adjustment and measurement system for steam turbine nozzle assembly

Description:
BACKGROUND OF THE INVENTION 
     The subject matter disclosed herein relates to a steam turbine nozzle assembly, or diaphragm stage. Specifically, the subject matter disclosed herein relates to an external adjustment and measurement system for a steam turbine nozzle assembly. 
     Steam turbines include static nozzle assemblies that direct flow of a working fluid into turbine buckets connected to a rotating rotor. The nozzle construction (including a plurality of nozzles, or “airfoils”) is sometimes referred to as a “diaphragm” or “nozzle assembly stage.” Steam turbine diaphragms include two halves, which are assembled around the rotor, creating horizontal joints between these two halves. Each turbine diaphragm stage is vertically supported by support bars, support lugs or support screws on each side of the diaphragm at the respective horizontal joints. The horizontal joints of the diaphragm also correspond to horizontal joints of the turbine casing, which surrounds the steam turbine diaphragm. 
     Conventionally, the nozzle assembly stages are aligned either with the rotor in place, or without the rotor, using a hard wire or laser measurement. In one conventional approach, the lower half of the nozzle assembly stage (or, nozzle lower half) and the rotor are aligned without the upper half of the nozzle assembly stage (or, upper half) and/or the upper half of the casing in place. In this approach, measurements are made between the lower half and the rotor at the bottom and each respective side of the turbine. In a second conventional approach, the nozzle upper half and casing upper half (as well as the respective lower haves) are in place without the rotor. In this approach, measurements are made between the bearing centerline locations and the nozzle assembly centerline. In either approach, the casing, rotor and/or nozzle assemblies must be removed in order to horizontally and vertically align these parts with respect to the rotor. These adjustments may be costly and time-consuming. 
     BRIEF DESCRIPTION OF THE INVENTION 
     A remote adjustment and measurement system for a steam turbine nozzle assembly is disclosed. In one embodiment, a steam turbine casing segment is disclosed including: a horizontal joint surface; a pocket having a first opening at the horizontal joint surface and a second opening facing substantially radially outward; and a port accessible from a radially outward surface of the steam turbine casing segment, the port fluidly connected to the second opening of the pocket. 
     A first aspect of the invention includes a steam turbine casing segment including: a horizontal joint surface; a pocket having a first opening at the horizontal joint surface and a second opening facing substantially radially outward; and a port accessible from a radially outward surface of the steam turbine casing segment, the port fluidly connected to the second opening of the pocket. 
     A second aspect of the invention includes a steam turbine apparatus having: a diaphragm segment; a casing segment at least partially housing the diaphragm segment, the casing segment having: a horizontal joint surface; a pocket having a first opening at the horizontal joint surface and a second opening facing substantially radially outward; and a port accessible from a radially outward surface of the steam turbine casing segment, the port fluidly connected to the second opening of the pocket; a support member positioned within the pocket; a support bar at least partially coupling the casing segment to the diaphragm segment, the support bar contacting the support member; and an adjustment assembly within the port and contacting the support member, the adjustment assembly configured to actuate movement of the support bar via the support member. 
     A third aspect of the invention includes a steam turbine system having: an upper casing segment; and a lower casing segment coupled to the upper casing segment at a casing horizontal joint surface, the lower casing segment including: a pocket having a first opening at the horizontal joint surface and a second opening facing substantially radially outward; and a port accessible from a radially outward surface of the steam turbine casing segment, the port fluidly connected to the second opening of the pocket. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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: 
         FIG. 1  shows a partial end elevation of a steam turbine nozzle adjustment and measurement system according to embodiments of the invention. 
         FIG. 2  shows a close-up partial end elevation of the steam turbine apparatus of  FIG. 1 . 
         FIG. 3  shows a partial cut-away three-dimensional perspective view of a steam turbine system according to embodiments of the invention. 
         FIG. 4  shows a partial cross-sectional view of a steam turbine system according to embodiments of the invention. 
     
    
    
     It is noted that the drawings of the invention are not to scale. The drawings are intended to depict only typical aspects of the invention, and therefore should not be considered as limiting the scope of the invention. In the drawings, like numbering represents like elements between the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Aspects of the invention provide for an adjustment and measurement system for a steam turbine nozzle assembly. In some embodiments, aspects of the invention provide for an external adjustment and measurement system for a steam turbine nozzle assembly. 
     In contrast to conventional approaches, aspects of the invention provide for an adjustment and measurement system for a steam turbine that reduces the time, cost and labor involved in aligning the steam turbine nozzle assembly, casing and rotor. In one embodiment, aspects of the invention provide for a steam turbine apparatus comprising: a diaphragm segment; a casing segment at least partially housing the diaphragm segment, the casing segment having: a horizontal joint surface; a pocket having a first opening at the horizontal joint surface and a second opening facing substantially radially outward; and a port accessible from a radially outward surface of the steam turbine casing segment, the port fluidly connected to the second opening of the pocket; a support member positioned within the pocket; a support bar at least partially coupling the casing segment to the diaphragm segment, the support bar contacting the support member; and an adjustment assembly within the port and contacting the support member, the adjustment assembly configured to actuate movement of the support bar via the support member. 
     Turning to  FIG. 1 , a partial end elevation of a steam turbine apparatus  10  is shown according to embodiments of the invention. In one embodiment, the steam turbine apparatus  10  may include an upper diaphragm segment  12  and a lower diaphragm segment  14  joined at a diaphragm horizontal joint surface  16  (interface between diaphragm segments). In one embodiment, upper diaphragm segment  12  and lower diaphragm segment  14  may be joined by at least one bolt  18 . Also shown at least partially housing diaphragm segments ( 12 ,  14 ) is a casing, including an upper casing segment  20  and a lower casing segment  22  joined at a casing horizontal joint surface  24  (interface between casing segments). In one embodiment, upper casing segment  20  and lower casing segment  22  may each include a support arm  26 ,  28 , respectively. As shown, upper casing segment  20  may include a slot  30  configured to receive an overhanging portion  32  of a support bar  34 , as is known in the art. Lower casing segment  22  may include a pocket  36  having a first opening  38  at the casing horizontal joint surface  24  (first opening  38  obscured in this two-dimensional view). Pocket  36  may further include a second opening  40  opening facing substantially radially outward (away from diaphragm segment  14  in the radial direction, indicated by the r-axis). 
     Lower casing segment  22  is further shown including a port  42  accessible from a radially outward surface  44  of lower casing segment  22 . In one embodiment, port  42  is fluidly connected to second opening  40  via, e.g., a channel or path  46 . In one embodiment port  42  (and consequently, path  46 ) may be substantially filled and sealed by a portion of an adjustment assembly  47  ( FIG. 2 , where labeling in  FIG. 1  is omitted for clarity of illustration). In one embodiment, port  42  (and consequently, path  46  may be substantially filled and sealed by adjustment bolt  50  (e.g., a bolt or screw, which may extend substantially radially), having a lug  51 . It is further understood that the adjustment assembly  47  (labeled in  FIG. 2 ) may include an adjustment member  52 , which may include, e.g., a member having an angled face (labeled in  FIG. 2 ). 
     Also shown included in steam turbine apparatus  10  is a support member  54  positioned within pocket  36 . In one embodiment, support member  54  may be configured to contact support bar  34  and may be configured to vertically support the support bar  34  at overhanging portion  32 . In one embodiment, support member  54  may include a metal including, e.g., steel. Support member  54 , in some cases, may be removably affixed to lower casing segment  22  (e.g., at support arm  28 ) via a bolt  56  (e.g., a shoulder bolt) or other attachment mechanism. For example, in some cases, support member  54  may be removably affixed to lower casing segment  22  via a pin or a screw. In one embodiment, lower casing segment  22  may include an aperture (e.g., a threaded aperture that may extend substantially radially outward, labeling omitted for clarity of illustration) configured to receive bolt  56  or another attachment mechanism for retaining support member  54  within pocket  36 . As described further herein, support member  54  may include an angled face configured to interact with an angled face of the adjustment member  52 , and actuate movement of the casing horizontal joint surface  24  with respect to diaphragm horizontal joint surface  16 . 
       FIG. 2  shows a close-up partial end elevation of the steam turbine apparatus  10  of  FIG. 1 . As shown in this close-up view, support member  54  may include an aperture  58  extending at least partially therethrough, the aperture  58  being configured to receive an attachment mechanism, e.g., a bolt  60 , for coupling the support member  54  to lower casing segment (at support arm  28 ). Support member  54  may further include an angled face  62 , configured to interact with a substantially complementary angled face  64  of adjustment member  52 . As is described further herein with respect to adjustment assembly  47 , the interaction of angled faces ( 62 ,  64 ), allows for translation of horizontal movement of adjustment bolt  50  (and adjustment member  52 ) into vertical (up or down along the z-axis) movement of support member  54 , and consequently, casing horizontal joint surface  24 . 
     In one embodiment, adjustment member  52  includes an aperture  66 , e.g., a threaded aperture configured to receive a portion of adjustment bolt  50 . In one embodiment, the aperture  66  may include a counter-bore portion for retaining adjustment bolt  50  at a position with respect to adjustment member  52 . In some embodiments, adjustment bolt  50  may be retained by a retaining member (not visible in this perspective) such as a retaining plate, tab, wire, etc. configured to fix adjustment bolt  50  in a desired position along the r-axis. In case, it is understood that adjustment member  52  and adjustment bolt  50  may be substantially coupled such that displacement of adjustment bolt  50  in the radial direction (r-axis) results in similar displacement of adjustment member  52  in the radial direction. 
     Turning to  FIG. 3 , a partial cut-away three-dimensional perspective view of the lower casing segment  22 , as well as adjustment assembly  47  (including the adjustment member  52  and adjustment bolt  50 ) and support member  54  is shown. Also shown is bolt  60  (e.g., a retaining shoulder bolt) or other attachment mechanism. As seen from this perspective, adjustment bolt  50  is accessible from the radially outward surface  44 , such that the radial position of adjustment bolt  50  may be adjusted while the steam turbine system is closed (e.g., when the casing horizontal joint surface  24  is not accessible). It is understood that the angles at which angled faces ( 62 ,  64 ,  FIG. 2 ) are formed may dictate the amount of vertical (z-axis) displacement that adjustment assembly  47  can impart on support member  54 . That is, a steeper angled face may allow for greater vertical displacement of support member  54  by adjustment member  52 , however, this steeper angle will increase the stresses placed on support member  54  and adjustment member  52 . In one embodiment, the angled faces ( 62 ,  64 ) may be formed at approximately five (5) to twenty-five (25) degrees with respect to normal. More specifically, in some embodiments, the angled faces ( 62 ,  64 ) may be formed at approximately ten (10) to approximately fifteen (15) degrees with respect to normal. 
       FIG. 4  shows a partial cross-sectional view of a steam turbine system  300  according to embodiments of the invention. It is understood that similarly labeled elements between the Figures herein may represent substantially similar elements. It is further understood that path  46  and associated port  42  (as well as details of support bar  34 ) are omitted for clarity of illustration. As shown, steam turbine system  300  may include diaphragm ring segments  12 ,  14 . Diaphragm ring segments  12 ,  14  are housed within casing segments  20 ,  22  (or, alternatively,  20  and  122 , as shown and described with reference to other embodiments), respectively, which are joined at casing horizontal joint surface  24 . In this depiction, casing horizontal joint surface  24  and diaphragm horizontal joint surface  16  are assumed to be aligned, and therefore, diaphragm horizontal joint surface  16  is omitted for clarity of illustration. Each diaphragm ring segment  12 ,  14 , supports a semi-annular row of turbine nozzles  370  and an inner web  360 , as is known in the art. The diaphragm ring segments  12 ,  14  collectively surround a rotor  380 , as is known in the art. Also shown included in steam turbine system  300  is an aperture  390  (several shown) extending radially from the rotor  380  to the radially outward surface  44 . Aperture  390  may be located axially (A-axis, into the page) between stages of the steam turbine system  300  (stages obstructed in this view), and in one embodiment, aperture  390  may be substantially sealed from the radially outward surface  44 , via, e.g., a cover plate, plug, or other removably affixed seal. In another embodiment, one or more apertures  390  may extend through a turbine nozzle  370  and/or through a nozzle sidewall, thereby intersecting the steam flow path. In one embodiment, aperture  390  may be located at the bottom-dead-center location of steam turbine system  300 , or slightly off from bottom dead center. In other embodiments, aperture  390  may be located proximate to the horizontal joint surfaces ( 16 ,  24 ) of casing and diaphragm. Further, multiple apertures  390  (e.g., four, approximately evenly spaced around the circumference of steam turbine system  300 ) may be formed within steam turbine system  300  to allow for access to the rotor  380  from a point external to the radially outward surface  44 . In one embodiment, apertures  390  may be configured to receive a probe or other measurement member to calculate a distance between portions of casing, diaphragm and/or rotor. It is understood that apertures  390  are located between stages of steam turbine system  300 , such that apertures  390  do not physically interfere with turbine nozzles  370  (indicated by phantom lines). In an alternative embodiment, one or more linear variable differential transformer(s) (LVDT)  392  may be placed between the rotor  380  and the diaphragm ring  12  (e.g., the turbine nozzles  370  within diaphragm ring  12 ) to collect and transmit data regarding positioning and movement of the diaphragm ring  12  and rotor  380 . LVDT  392  may be any conventional linear variable differential transformer configured to transfer the physical movement of an element to which it is attached, to an electrical signal, as is known in the art. LVDT  392  may be hard-wired to a receiving system (e.g., a conventional receiver or other computerized system) or may be wirelessly connected to the receiving system. In any case, LVDT  392  may be configured to determine a position and/or movement of diaphragm ring  12  and rotor  380 . In another embodiment, a conventional piezoelectric-based device and/or a conventional capacitance device may be used in place of LVDT  392  to determine position and/or movement of the diaphragm ring  12  and rotor  380 . In some embodiments, these devices (e.g., LVDT  392 , piezoelectric-based device or capacitance device) may only have to survive the initial static conditions of the steam turbine system  300 . That is, in some embodiments, one or more of these types of devices will be relatively ineffective for collecting and/or transmitting positional or movement-related data after operation of the steam turbine system  300  begins. 
     In contrast to conventional steam turbine systems, steam turbine system  300  may allow for determination of the positional relationships between a rotor, diaphragm, and casing at one or more locations along the circumference of the system. Specifically, steam turbine system  300  may provide for measurement of positional relationships of its components while the system is closed (e.g., where casing segments  20 ,  22 , diaphragm segments  12 ,  14  and rotor  380  are in place. This system  300  may reduce the time and expense of measurement associated with conventional systems that require removal of at least some components (e.g., casing, diaphragm and/or rotor) in order to conduce measurements. 
     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. 
     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.