Abstract:
A tool for installing or uninstalling a segment of an inner housing of a turbomachine. The turbomachine includes an outer housing, at least partially surrounding an inner housing and a rotor, concentrically arranged within the inner housing. The rotor is equipped with a number of rotor grooves. The inner housing is divided at an essentially horizontal split plane into an upper segment and a lower segment. The tool includes a first portion insertable into any of the rotor grooves, and furthermore includes a second portion disposed at a distance from the first portion. This second portion is connectable to the lower segment of the inner housing.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to European application 14160939.6 filed Mar. 20, 2014, the contents of which are hereby incorporated in its entirety. 
       TECHNICAL FIELD 
       [0002]    The present invention relates to a tool for removing an inner casing from a turbomachine. A turbomachine in the context of this description is a machine having an inner housing, an outer housing, at least partially surrounding said inner housing, and a rotor, concentrically arranged within the inner housing, the rotor being equipped with a number of blades, inserted into rotor grooves, and wherein the inner housing is divided at an essentially horizontal split plane into an upper part and a lower part. In particular, such turbomachines are axial turbines or axial compressors. 
       BACKGROUND 
       [0003]    Components in a turbomachine, particularly blades and vanes in a gas turbine, have to withstand very hard operating conditions, thus they need periodical checks and controls. 
         [0004]    Different methods are known to get access to the vanes and blades. 
         [0005]    For example, firstly the upper part of the outer casing is removed, then, secondly, the upper part of the inner casing is removed, and at least the rotor is removed in order to access the vanes at the bottom part of the inner casing. 
         [0006]    It is a disadvantage of this method that removing of the rotor is very time consuming and requires complex lifting equipment. Therefore, this method is avoided, whenever possible. 
         [0007]    For avoiding said disadvantage it is alternatively known, firstly to remove the upper part of the outer casing, secondly to remove the upper part of the inner casing, then to replace the upper part of the inner casing by a half-ring segment and then to provide rollers between the lower parts of the outer and the inner casing. 
         [0008]    This way, the lower part of the inner casing can be rotated on the rollers, bringing it to the top of the machine, such that it can be removed without removing the rotor. 
         [0009]    This method can cause damages between the adjacent parts of the inner and outer casing. For example, this can be caused by the possible relative axial displacement of the inner and outer casing, such that adjacent surfaces of the inner and outer casing that normally are separated by a gap, come into contact. A risk to damage sensitive parts is immanent. 
         [0010]    According to a non-disclosed method for removing the inner casing from a turbomachine, having an outer casing, an inner casing within the outer casing and a rotor within the inner casing, the risk of damages is avoided by conducting the following steps: (1) removing the upper part of the outer casing, (2) removing the upper part of the inner casing, (3) connecting the lower part of the inner casing to the rotor, such that the lower part of the inner casing is supported by the rotor, (4) rotating the rotor around its longitudinal axis to roll out the lower part of the inner casing to an accessible position, (5) removing the lower part of the inner casing. 
         [0011]    This method allows rotation of the inner casing without the need of providing supports from a static part against the inner casing, e.g. between the inner casing and the outer casing. These supports could deform the inner casing and thus change the relative distance between rotor and inner casing, with the risk of damaging rotor or stator components. 
         [0012]    In addition, this method allows rotation of the inner casing around the rotor axis, but this rotation is not carried out by sliding the inner casing on supports. This is advantageous, because the tolerances of the inner casing are such that during rotation (the inner casing slides on supports) the distance between rotor and inner casing can change with the risk of damaging. 
         [0013]    This method requires a suitable tool to support the lower segment of the inner casing in a defined distance to the rotor. 
       SUMMARY 
       [0014]    It is an object of the present invention to provide a tool for installing or uninstalling the lower segment of the inner housing of a turbomachine, which allows a fixed connection between the inner casing and the rotor of the turbomachine at a defined distance. 
         [0015]    This object is obtained by a tool for installing or uninstalling the lower segment of the inner housing of a turbomachine according to claim  1 . 
         [0016]    The tool according to the invention comprises a first portion, this portion being insertable into a rotor groove, and furthermore comprises a second portion, disposed at a distance from the first portion, and this second portion being connectable to the lower segment of the inner housing. 
         [0017]    According to a preferred embodiment said first portion of the tool is complementarily designed to the shape of the rotor grooves, e.g. designed as a fir tree. 
         [0018]    According to another embodiment the tool comprises a first portion, designed for insertion into any of the rotor grooves, a second portion, designed to be connected to a part of the lower segment of the inner housing, and a platform connecting said first portion to said second portion. 
         [0019]    Preferably, that second portion is designed as an essentially rectangular connection plate, being essentially orthogonally joined to said platform. 
         [0020]    For increasing the strength of the tool the platform and the connection plate may be supported by at least one stiffener, such as a stiffening plate, joined to the narrow sides of both, the platform and the connection plate. 
         [0021]    For connecting the tool to a part of the lower segment of the inner housing the second portion is equipped with one or more through holes for a fastener, e.g. at least one screwed bolt, to be screwed into said part of the lower segment. 
         [0022]    Said part of the lower segment of the inner housing may be an accessible surface of the lower segment. Preferably, the second portion of the tool is designed to be connected to the surface at the split plane. 
         [0023]    Alternatively, the removed upper segment of the inner housing is replaced by at least one dummy half ring. In this case the second portion of the tool is designed to be connected to this half ring. An advantage of this embodiment is the easy access to the relevant components for installing the tool. 
         [0024]    According to just another embodiment instead of a dummy in form of a complete half ring, two dummy segments are attached to the lower housing segment. To each of the both ends in the split plane a dummy segment is attached. At least two tools according to this invention connect the rotor with these dummy segments and in so doing with the lower housing segment. 
         [0025]    The use of the inventive tool for installing or uninstalling the lower segment of an inner housing of a turbomachine implicates a number of advantages. 
         [0026]    The inner casing segment is connected to the rotor. It is reliably locked in its position, especially its radial position, by mounting in rotor blade grooves. When being rotated with the rotor, a defined and constant radial distance between sensitive parts is ensured. 
         [0027]    The application of the tool according to this invention does not require any additional machining of the sensitive rotor. 
         [0028]    Compared to the known method of insertion of additional rollers between the outer casing and the inner casing for rolling out the lower segment of the inner housing the use of the inventive tool effects a significant decrease of expenditure of work and time. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]    Further characteristics and advantages of the invention will be more apparent from the description of a preferred but not exclusive embodiment of the inventive tool and its use, illustrated by way of example in the accompanying drawings, in which: 
           [0030]      FIGS. 1 through 6  illustrate schematically the steps of removing the lower segment of the inner housing from the turbomachine; 
           [0031]      FIG. 7  illustrates the tool during operation, i.e. the tool connected to the rotor and to the lower segment of the inner housing; 
           [0032]      FIG. 8  illustrates the assembly of the tool according to the invention; 
           [0033]      FIGS. 9 through 12  show different options of use of the tool. 
       
    
    
     DETAILED DESCRIPTION 
       [0034]    A gas turbine  1  includes an outer housing  2  with an upper segment  3  and a lower segment  4 , in addition it includes an inner housing  5  with an upper segment  6  and a lower segment  7 . The upper and lower segments  3 ,  6 ,  4 ,  7  of the outer and inner housings  2 ,  5  are divided at a split plane  9  with an essentially horizontal axis. 
         [0035]    The inner housing  5  houses a rotor  10  rotating around a longitudinal axis  11 . 
         [0036]    The inner housing  5  is a vane carrier, equipped with vanes  12 . The rotor  10  is equipped with radially extending blades  13 , fixed in rotor grooves with a fir tree profile  14  by a foot with a complementary fir tree profile  14 . 
         [0037]    In order to remove the inner housing  5  without removing the rotor  10  the following steps are carried out. 
         [0038]    The upper segment  3  of the outer housing  2  is removed ( FIG. 2 ); then the upper segment  6  of the inner housing  5  is removed ( FIG. 3 ). 
         [0039]    Afterwards the lower segment  7  of the inner housing  5  is fixedly connected to the rotor  10  by the tool  15 .  FIG. 4  shows schematically that the tool  15  is connected to the lower segment  7  at a surface in the split plane  9 . Other suitable attachment surfaces are inwardly extending projections of the inner housing  5 . Possible options for directly or indirectly connecting the tool  15  to the inner housing  5  are disclosed in connection with the discussion of  FIGS. 9 through 12 . 
         [0040]    After the fixed connection between rotor  10  and the lower segment  7  by the tools  15  is completed, the rotor  10  is slowly rotated by a half turn around its longitudinal axis  11 . Driven by the rotor  10 , the lower segment  7  moves to an upper position ( FIG. 5 ) and is now accessible either for a check or for removing it from the machine ( FIG. 6 ). 
         [0041]    To connect the tool  15  with the rotor  10 , as schematically shown in  FIG. 7 , at least one blade  13  is removed from a rotor groove to open up a free place in the rotor groove. In a next step, the inventive tool  15  is inserted into the opened up place in the rotor groove. For this purpose, as shown in  FIG. 8 , the tool  15  is equipped with a first portion  16 , designed and dimensioned in accordance with the profile  14  of the rotor grooves, in this example designed as a fir tree  14  with the same parameters as the complementary rotor groove profile  14 . By this fir tree foot  16  the tool  15  is fixed in the rotor  10  (see  FIG. 7 ). Again referring to  FIG. 8 , a second portion  17  of the tool  15  is designed and dimensioned in such a way that it can be connected directly or indirectly to the lower segment  7  of the inner housing  5 . First portion  16  and second portion  17  are connected to each other by a platform  23 . This second portion  17  comprises a rectangular connection plate  18 . And this connection plate  18  is equipped with a suitable fastener to fixedly connect the tool  15  to the inner housing  5 . These fasteners may be means for a form-locking or a friction-locking join. According to one embodiment the connection plate  18  is equipped with through holes  21  for a fastener, such as a screwed bolt to be screwed in an adjacent part of the inner housing  5 . A stiffener, e.g. a stiffening plate  22 , is joined to the narrow sides of the platform  23  and the connection plate  18  to increase the mechanical stability of the tool  15 . 
         [0042]      FIG. 9  schematically illustrates a first advantageous option, how to apply the inventive tool for installing or uninstalling the lower segment  7  of the inner housing  5 . After having removed the upper segment  6  of the inner housing  5  from the machine  1 , the upper segment  6  is replaced by a dummy in form of a half ring  19 . At the split plane  9  the ends of the dummy half ring  19  and the lower segment  7  are connected. In three different circumferential positions at the upper part of the rotor  10  a blade  13  is removed from the rotor  10 . Into the opened up free place of the respective rotor groove the foot  16  of tool  15  is inserted. By connection plate  18  the tool  15  is fixedly joined to the dummy half ring  19 . For example three tools  15  are used to connect rotor  10  and dummy half ring  19 . The e.g. three tools  15  may be joined exclusively—as shown in this figure—to the dummy half ring  19 . It is an advantage of this alternative that the tool  15  and the dummy half ring  19  can be equipped with specifically adapted contact areas  21  at an easily accessible place. For example, this provides the option to equip these areas  21  with purpose-adapted, easily manageable fixing means. One preferred option for connecting the tool  15  to the dummy ring  19 —and therewith to the lower housing segment—is to equip the connection plate  18  of the tool  15  with through holes  23  for screw bolts and to screw these bolts in provided threaded holes at the dummy  19 . But, as mentioned, any other suitable joints are possible. 
         [0043]    Of course there is also an option to join a part of the tools  15  to the dummy  19  and to join another part directly to the lower segment  7 . 
         [0044]    Advantageously, the dummy ring  19  is positioned at an axial level with the possibility of easily removing a number of blades  13  from the rotor  10  and thereat inserting the tools feet  16  into a rotor groove. 
         [0045]    Usually, between two and four tools  15  are used to fixedly connect the lower segment  7  with the rotor  10 . 
         [0046]    Another option how to use the inventive tool is illustrated in  FIG. 10 . Instead of connecting a complete half ring  19  to the lower segment  7 , only two segments of such a ring are applied. At the split plane  9  the two dummy segments  20  are attached to the lower segment  7  at a suitable axial level of the machine  1  and by using, whenever possible, the existing connection members at the segment  7 . The dummy segments  20  are designed to provide contact surfaces for the connection plates  18  of tools  15  and the fasteners.  FIG. 10  shows an embodiment using four tools  15  to fixedly connect the rotor  10  with the inner segment  7 . According to this preferred embodiment four tools  15  are used. Again: It is also possible to join a part of the tools  15  to the dummy segments  20  and to join the remaining tools  15  directly to the housing segment  7 . 
         [0047]      FIG. 11  illustrates an option of use the inventive tool that requires the least expenditure of time and work. Two tools  15  are used, thereby one tool  15  is attached to each end face of the lower segment  7  in the split plane  9 . The design of the connection plates  18  of tools  15  is adapted to the existing connection members of segment  7  in the split plane  9 . With low expenditure of work and time the said first portion  16  of the tool  15 , usually a foot with fir tree profile  14 , is inserted in a free place in a rotor groove in the split plane  9  and the second portion  17  of the tool  15  is joined by screw bolts to the lower housing segment  7 . 
         [0048]      FIG. 12  illustrates an embodiment with direct connection of a number of tools  15 , e.g. three tools  15 , to the lower segment  7  at different circumferential positions. For this purpose suitable contours at the segment  7  may be used. 
         [0049]    In practice the materials used and the dimensions can be chosen at will according to requirements and to the state of the art.