Abstract:
A clamp assembly for facilitating attachment and removal of a first component to or from a second component includes plural clamp bodies, each having at least two mutually perpendicular surfaces arranged about the first component. A substantially rigid ring is located between one surface of the clamp body and a surface of the first component. At least one fastener is provided for each of the plural clamp bodies, adapted to extend through a respective one of the plural clamp bodies and into the second component. Tooling is provided to allow for simultaneous tightening or loosening of all bolts on a single combustor.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to gas turbine combustor technology and, more specifically, to a quick disconnect combustor endcover or casing assembly. 
     In certain land-based power generation gas turbine engines, plural combustors are arranged in an annular array about the turbine rotor to provide for the combustion of fuel and to guide the energized combustion products into the turbine section to drive the turbine. Each combustor typically includes an outer casing which defines the external boundary of the combustor, a flow sleeve for distributing compressor discharge air to the head end of the combustor while cooling a liner which encloses the combustion process, and a transition piece for flowing the combustion products into the turbine section. The combustor also includes a plurality of fuel nozzles coupled to an endcover at the head end of the combustor. Air and fuel are supplied through the endcover to the fuel nozzles for combustion within the liner. 
     Current technology utilizes conventional multi-bolt, metallic flange-on-flange connections for attaching endcovers to turbine casings. Since the combustor is one of most frequently-inspected and replaced gas turbine components, improving access to the combustor internals, via the endcover, would be a key step toward minimizing outage durations and maximizing turbine availability. Accordingly, there remains a need for a combustor endcover or casing that is easily removed and reinstalled to shorten service outage duration while retaining sealing requirements with the combustor. 
     BRIEF SUMMARY OF THE INVENTION 
     In accordance with an exemplary but nonlimiting embodiment, the invention provides a clamp assembly for facilitating attachment and removal of a first component to or from a second component comprising plural clamp bodies, each having at least two mutually perpendicular surfaces arranged about the first component; a substantially rigid ring located between one surface of the clamp body and a surface of the first component; and at least one fastener for each of the plural clamp bodies adapted to extend through a respective one of the plural clamp bodies and into the second component. 
     In another aspect, the invention provides an assembly comprising a combustor casing and an endcover attached to a compressor discharge casing; plural clamp bodies, each having at least two mutually perpendicular surfaces arranged about the endcover or combustor casing; a substantially rigid stiffener ring located between one surface of the clamp body and a surface of the endcover or combustor casing; and at least one fastener for each of the plural clamp bodies adapted to extend through a respective one of the plural clamp bodies and into the casing. 
     In still another aspect, the invention provides a combustor casing assembly comprising a combustor casing and an endcover attached to a forward end of a compressor discharge casing; plural clamp bodies, each having at least two mutually perpendicular surfaces arranged about the combustor casing; a substantially rigid stiffener ring located between one surface of the clamp body and a surface of the combustor casing; at least one fastener for each of the plural clamp bodies adapted to extend through a respective one of the plural clamp bodies and into the compressor discharge casing; and tooling for simultaneously tightening or loosening the at least one fastener of each of the plural clamp bodies. 
     The invention will now be described in detail in connection with the drawings identified below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic illustration of a combustor for gas turbine; 
         FIG. 2  is a schematic end view of a combustor endcover in accordance with a first exemplary but nonlimiting embodiment of the invention; 
         FIG. 3  is a side elevation view of the endcover shown in  FIG. 2 ; 
         FIG. 4  is an end elevation of a combustor endcover in accordance with a second exemplary but nonlimiting embodiment of the invention; 
         FIG. 5  is a side elevation of the endcover shown in  FIG. 4 ; 
         FIG. 6  is an end view of a casing assembly in accordance with a third exemplary but nonlimiting embodiment of the invention; and 
         FIG. 7  is a schematic diagram of an arrangement for simultaneously tightening or loosening the casing bolts. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  illustrates a combustor employing an endcover assembly in accordance with conventional practice. The combustor, generally designated  10 , includes an outer casing  12 , a flow sleeve  14 , a liner  16 , a transition piece  18 , an endcover  20  and a plurality of fuel nozzles  22 . In typical gas turbine combustors of this type, the flow sleeve  14  distributes compressor discharge air into the combustor while cooling the liner  16 . The endcover  20  encloses the head end of the combustor, supplies purge air and fuel to the fuel nozzles  22 , and forces air into the head end of the liner by way of the fuel nozzle bodies. The liner  16  provides an enclosure for the combustion process, while the transition piece  18  guides the products of combustion into the turbine section  24 , the first stage stator vane of which is illustrated at  26 . External plumbing  28  connects to the endcover assembly  20  for supplying air and fuel to the nozzles  22 . 
       FIGS. 2 and 3  illustrate an exemplary but nonlimiting embodiment of an endcover assembly  30  which, for clarity and ease of understanding, is shown to include an endcover  31  having a round shape including flat inside and outside surfaces  32 ,  34  respectively and a peripheral edge  36 . Fuel nozzles and other plumbing components have been omitted. 
     During assembly of the endcover to the combustor, stiffener ring  38  is applied over the outside surface  34  of the endcover  31 , noting that the outside diameter of the stiffener ring is substantially equal to the outside diameter of the endcover. 
     A plurality of clamps  40  are located about the stiffener ring circumference, each clamp having an axial section  42  and a radially-inwardly directed flange  44 . An inside surface  46  of the axial section  42  engages the peripheral edge  36  of the endcover and the adjacent peripheral edge  48  of the stiffener ring. At the same time, an interior flange surface  50  of the inwardly-directed radial flange  44  engages the outer surface  52  of the stiffener ring. While the clamps are shown to be substantially L-shaped, the shapes may vary, but it is advantageous to have the inside surfaces  46  and  50  of the clamp engage edge  36  and surface  52 . 
     In the exemplary but nonlimiting embodiment, four clamps  40  are located at substantially, circumferentially-equally-spaced locations about the stiffener ring (i.e., at substantially 90° intervals). Standard or hydraulic bolts  56 , each of which includes a head  58  and a threaded shank  60 , extend through the clamps and through a flange of the combustor casing  62 . Each bolt is securely fastened by means of a nut  64  threaded on the shank  60  of the bolt, such that the endcover  31  and stiffener ring  38  are clamped between the radial flanges  44  and the combustor casing  62 . In the exemplary embodiment, each clamp  40  may have an axial thickness dimension of about six inches, determined to be sufficient to resist any tendency of the endcover  31  to buckle or bend during use. Thus, the clamps  40 , along with the stiffener ring  38 , are designed such that they can insure an adequate, uniform sealing force when the endcover  31  is attached to the combustor casing  62  using typical Flexitallic™ or similar type gaskets, while minimizing the number of bolted connections required. It will be understood that the number and dimensions of the clamps  40  may vary with specific applications. 
     In this first exemplary embodiment, each bolt  56  may be hydraulically tensioned and, while tensioned, the nut  64  can be easily applied. After the nut  64  is tightened to specifications, the hydraulic tension force is removed and the cover  31  and stiffener ring  38  are loaded in compression. 
     With reference now to  FIGS. 4 and 5 , a second exemplary but nonlimiting embodiment of an endcover assembly  66  is illustrated. This embodiment is substantially identical to the embodiment illustrated in  FIGS. 2 and 3  and, accordingly, like-reference numerals are used to designate correspondingly-identical components. In this embodiment, however, the standard or hydraulic bolts  56  are used with conventional helicoil inserts  68  in combination with differently configured casing  70 . The helicoil inserts  68  are threaded directly into the casing  70 , and the bolts  56  are, in turn, threaded into the inserts. 
     Referencing  FIG. 6 , similar clamps  40  and bolts  56  are employed to secure a substantially-cylindrical combustor casing  72  to compressor discharge casing  74  using a similar but re-sized stiffener ring  76 , downstream of the combustor endcover  78 . The bolts  56  may be used with nuts  64  as shown in  FIG. 3  or with helicoil inserts  68  as shown in  FIG. 5 . The clamp construction, number and spacing of the clamps and the operation of the clamps are as otherwise described above. This arrangement would prove especially useful in combustor arrangements where access to the combustor internals is provided at a location other than the endcover  78  where the entire casing (combined  78  and  72 ) are removed as a single unit. 
     Turning to  FIG. 7 , the clamps  40  are substantially identical to those used in the embodiments described above, but in this embodiment the circumferentially-spaced clamps are connected by individual, flexible clamp connectors  80  that are able to flex in either of two opposite circumferential directions. The flexible connectors  80  can serve as a guide on which removal/installation tooling (not shown) can glide, facilitating alignment with the bolts  82  of the individual clamps  40 . In this regard, additional speed may be achieved by designing tooling for simultaneously removing or installing the bolts  82  from each of the clamps  40 . The use of the clamp connectors  80  will also ensure that the technician on site can remove the entire assembly rather than handling four individual sets of clamp components. Furthermore, because the flexible connectors  80  provide two degrees of freedom, if one or more bolts are removed, the flexible connectors  80  are still able to hold the assembly together. 
     Also shown (schematically) in  FIG. 7  are hydraulic fittings  84  located over the bolts  82  and connected via hydraulic lines  86  to a hydraulics distribution box  88  which, in turn, is connected to a control box or panel  90 . With all of the clamps  40  connected, the tooling will engage all of the bolts or fasteners  82  simultaneously and apply torque to tighten (or loosen) the bolts. A manifold for the hydraulics to ensure equal pressure distribution and therefore applied force is advantageous and well within the state of the art. Tooling for simultaneously tightening or loosening the bolts is available from, e.g., Nova Machine Products (Hydranut Bolt Tensioning System), and Jetyd Corp., with only normally expected adaptations required to the tooling for use in the context of the endcover assemblies described herein. 
     In addition to speeding up the assembly/disassembly process, the described tooling also affords a much more uniform sealing arrangement that avoids any distortions or gasket crimping that would occur if the bolts were handled individually. 
     While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.