Abstract:
A turbomachine foot unit with a plurality of feet is provided. The plurality of feet is fastened to a turbomachine. The turbomachine stands upright on a horizontal base. The turbomachine foot includes fastening devices for fastening the feet to the base. At least one of the feet is mounted in a horizontally moveable manner relative to one of the fastening devices fastening the foot to the base.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is the U.S. National Stage of International Application No. PCT/EP2009/067776 filed Dec. 22, 2009, and claims the benefit thereof. The International Application claims the benefits of German Patent Application No. 10 2008 064 371.8 DE filed Dec. 22, 2008. All of the applications are incorporated by reference herein in their entirety. 
     FIELD OF INVENTION 
     The invention relates to a turbomachine foot unit with a plurality of feet for fastening to a turbomachine and for standing the turbomachine on a horizontal base and with fastening means for fastening the feet to the base, with the turbomachine fastened on the base at least one of the feet being mounted so as to be horizontally movable in relation to one of the fastening means which fastens the foot to the base. 
     BACKGROUND OF INVENTION 
     Turbomachines for industrial purposes or in power stations are often connected to an electrical machine, for example a turbocompressor is connected to an electric motor for driving the turbocompressor or a turbine is connected to a generator for the transmission of force from the turbine to the generator. So as not to subject the connecting shaft to excessively high load when force is transmitted between the machines, such a turbomachine is usually fastened on a base, for example a foundation or base frame. The turbomachine rests on this so as to be firmly fixed during operation, the firm fixing also counteracting vibrations of the turbomachine. 
     To fasten the turbomachine on a base, it is known to place the turbomachine on feet which are screwed firmly to the base. The feet are themselves connected to the turbomachine, for example welded or cast in one piece with a housing element, so that the turbomachine is firmly anchored in the base. 
     EP 1 176286 A1 already discloses a turbocharger with symmetrical long hole fastening. U.S. Pat. No. 4,076,452 A, U.S. Pat. No. 5,108,258 A and WO 98/53183 A1 show turbines with various bearer constructions. 
     SUMMARY OF INVENTION 
     An object of the present invention is to specify a turbomachine foot unit, by means of which a turbomachine for industrial or power station use can be anchored securely to a base. 
     This object is achieved by means of a turbomachine foot unit of the type initially mentioned, in which, according to the invention, with the turbomachine fastened at the base, at least one of the feet is mounted so as to be movable horizontally in relation to one of the fastening means which fastens the foot to the base. 
     The invention in this case proceeds from the consideration that a turbomachine becomes hot while it is in operation, the heat being distributed unevenly in the volume of the turbomachine. For example, in the case of an air compressor, the air compressed to an increasingly greater extent from stage to stage becomes warmer, so that the turbomachine is relatively cool at the air inlet and is hot at the outlet of the compressed air. As a result of the heat, the turbomachine as a whole expands, with the result that stresses and deformations are transferred to feet fixed firmly to the base. In the case of a frequent change in temperature of the turbomachine, the feet or the foot unit of the turbomachine therefore experience fatigue, and because of this material fatigue is hazardous to secure fastening to the base. Owing to the movability of at least one of the feet in relation to the horizontal base or to a fastening means fixed to the base, the corresponding foot can participate in length compensation, so that the mechanical load on this foot is reduced, as compared with firmly fixed feet. 
     The base may be a foundation. A base frame, intermediate plate or the like may also be a base, these then expediently being fastened firmly to the foundation or ground, that is to say are immovable with respect to the ground. The feet serve for fastening to the turbomachine and are expediently fastened, for example welded, to it. In the case of a turbomachine fastened on the base, it is expediently fastened to the base for the purpose of carrying out its regular operation. The turbomachine may be a turbocompressor or a turbine and is intended, in particular, for a power output of at least 100 kW, in particular at least 500 kW. There may be any number of feet. Four movable feet are advantageous, more movable feet or, for example, two movable and two immovable feet also being conceivable. 
     Movability is expediently movability along the base. Movability may be one-, two- or three-dimensional movability, although the second and/or third dimension must not be a horizontal dimension. 
     In an advantageous embodiment of the invention, at least two of the feet are mounted so as to be horizontally movable independent of one another in relation to the fastening means. As a result, they can adapt their position especially flexibly even to a complex thermal expansion behavior of the turbomachine. Independent movability is afforded when one foot is movable, without forced movement of another foot consequently taking place. 
     A sliding arrangement, for example of the foot over the base, is sufficient for movable mounting. Movability may be facilitated by a movement aid, for example a surface or track which is provided for especially low-friction sliding of two components one on the other, for example by an especially smooth surface or a lubricant. 
     Movability between the movable foot and its fastening means can be achieved in an especially simple way by play between the fastening means and the feet. Relative movement can take place one-, two- or three-dimensionally within this play. 
     Advantageously, the movable foot comprises a foot plate with a recess, through which is led a fastening means which is assigned to the foot and which fastens the foot to the base, the foot plate being moved in relation to the fastening means in the event of horizontal movement of the foot. The horizontal size of the recess thus permits the horizontal movability of the feet. The recess is expediently surrounded completely by the foot plate. The fastening means may be a screw which is screwed in the base. Its screw head can directly or indirectly fix the foot plate vertically. 
     The fastening means especially advantageously comprises a sleeve with a collar, said sleeve surrounding the screw. The collar can thereby fix the foot plate vertically, so that, independently of manufacturing accuracies of the screw, a uniform apportionment of force to the foot plate for the purpose of fixing the foot plate can be achieved. 
     Moreover, the sleeve can limit a pressure force of the screw upon the foot plate, for example in that said sleeve bears part of the pressure force of the fastening means on the base. As a result, the clamping force which the screw exerts on the foot plate, independently of the tightening force of the screw, can be adjusted to a maximum value which allows horizontal movement of the foot plate over the base, without excessive frictional force having to be overcome. Expediently, the length of the sleeve as far as the collar is equal to the thickness of the foot plate between the base and the collar or a collar support of the foot plate. 
     To facilitate the horizontal movement of the feet, a friction-reducing means, for example a viscous lubricant or Teflon, may be introduced between the collar and foot plate. The same applies to a connection between a foot plate and a foundation or ground. 
     In a further advantageous refinement of the invention, the turbomachine foot unit comprises a fixing means fastened on the base, for fixing part of the turbomachine at a horizontal fixed point against horizontal movement. The horizontal movement of the turbomachine permitted by the feet can thereby be restricted, so that, for example, a shaft connection to an electrical machine is not subjected to excessively high mechanical loads. 
     What may be understood as being a horizontal fixed point is a point or location, for example on the turbomachine, at which horizontal movability is prevented. Thus, at the horizontal fixing point, fixing takes place in all horizontal directions. The fixing means may be a shaped-out portion, for example a bolt, which is fastened to the base and which engages into a corresponding recess on the turbomachine or on the foot unit, or vice versa, so that a shaped-out portion on the turbomachine or foot unit engages into a recess fastened to the base. 
     Expediently, the movable foot and, in particular, all the movable feet are mounted so as to be movable away from the horizontal fixed point and toward the horizontal fixed point, for example in a star-shaped manner, so that expansion of the turbomachine away from the fixed point can be converted into a corresponding movement of the feet. 
     The turbomachine is fixed perpendicularly to the base by means of the feet. In order to allow thermal expansion, for example in the vertical direction, the fixing means advantageously allows vertical movement of the turbomachine. Overdetermined fixing can thereby be avoided. 
     The fixing means advantageously lies in a vertical mid-plane which runs through a rotor shaft of the fastened turbomachine. A horizontal position of the shaft of the turbomachine can thereby be fixed, so that, in the event of thermal expansion of the turbomachine, the shaft is subjected to only slight mechanical load. To the same advantage, the fixing means is arranged on a side of the turbomachine which faces a drive, for example an electric motor for driving the turbomachine designed as a compressor, or which faces a generator in the case of a turbine. 
     It is proposed, furthermore, that the turbomachine foot unit comprise a guide means fastened to the base, for restricting the horizontal movement of part of the turbomachine to one-dimensional movement. The guide means may be a center guide chock which serves as a radial fixed point for preventing a rotation of the turbomachine in the horizontal. A load on the shaft can be kept low. 
     For this purpose, the one-dimensional movement is expediently directed in a shaft direction parallel to a rotor shaft of the fastened turbomachine. Moreover, it is advantageous if the guide means lies in a vertical mid-plane which runs through a rotor shaft of the fastened turbomachine. In order to keep load upon the shaft in the shaft direction low, in particular at a connection to an electrical machine, it is advantageous if the guide means is arranged on a side of the turbomachine which faces away from the drive. 
     Moreover, the invention is aimed at a turbomachine with a turbomachine foot unit, as described above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is explained in more detail by means of exemplary embodiments illustrated in the drawings in which: 
         FIG. 1  shows a perspective diagrammatic illustration of a turbomachine and of a turbomachine foot unit fastened to it and having four feet, 
         FIG. 2  shows a fixing diagram in the form of a view of the base from above, 
         FIG. 3  shows a further turbomachine foot unit in a perspective view, 
         FIG. 4  shows a sectional illustration through a foot of the turbomachine foot unit from  FIG. 3 , 
         FIG. 5  and  FIG. 6  show respectively a sectional illustration and a top view of a center guide chock of the turbomachine foot unit from  FIG. 3 , 
         FIG. 7  and  FIG. 8  show respectively a sectional illustration of the top view of a center guide bolt of the turbomachine foot unit from  FIG. 3 , and 
         FIG. 9  shows a turbomachine foot unit on a raised base. 
     
    
    
     DETAILED DESCRIPTION OF INVENTION 
       FIG. 1  shows a turbomachine  2  in a diagrammatic perspective illustration, with a turbomachine foot unit  4  which is welded to a housing  16  of the turbomachine  2 . The turbomachine foot unit  4  stands on a base  6 , indicated in  FIG. 1 , which extends horizontally and comprises a planar foundation and, on each foot  8 , a foot plate  11 . The turbomachine foot unit  4  comprises four feet  8 , each with a foot plate  10  and with two foot panels  12 ,  14  which stand perpendicularly to one another and are welded to the housing  16  of the turbomachine  2 . The two foot panels  12 ,  14  are welded to the foot plate  10  at their end lying opposite the turbomachine  2 . In each case two feet  18  are connected to one another in each case via a transverse panel  18 . It is likewise conceivable that in each case two foot panels  14  and one transverse panel  18  are produced in one piece and the foot panels  12  are in two parts and are welded to a foot panel  14  on both sides. 
     Moreover,  FIG. 1  illustrates in the manner of an exploded drawing a fixing means  20 , shown in more detail in  FIGS. 7 and 8 , and also a guide means  22 , illustrated in more detail in  FIGS. 5 and 6 , and, for each foot  8 , in each case a sleeve  24  which is shown larger in  FIG. 4 . 
       FIG. 2  shows a fixing diagram of the turbomachine  2  on the base  6  or its intermediate plates  11 . What are illustrated are four fastening locations  26  for the feet  8  on the base  6 , a fixing point  30  defined by the fixing means  20 , and a guide region  32  which is defined by the guide means  22 . Moreover, a dashed line indicates a shaft  34  of a rotor of the turbomachine  2 , said shaft being mounted by means of two shaft radial bearings  36  and one shaft axial bearing  38 . Also indicated is a coupling  40  to a drive, not illustrated, for example an electric motor in the case of a turbomachine  2  designed as a compressor. 
     The fixing means  20  is placed vertically below the rotor shaft  34 , so that the latter is arranged in a vertical mid-plane which runs perpendicularly with respect to the paper plane and runs through the rotor shaft  34  of the fastened turbomachine  2 . 
     As explained in more detail with reference to the following figures, the feet  8 , in the state fastened on the base  6 , are movable in the horizontal longitudinal direction  42  and horizontal transverse direction  44  or only in the horizontal transverse direction  44 , so that they essentially participate in a thermal expansion or contraction movement of the turbomachine  2 , and therefore a shear force on the feet  8  or on the foot panels  12 ,  14  and their welded joints and also on the fastening means  60  ( FIG. 4 ) remains low. The horizontal longitudinal direction  42  is parallel to the longitudinal direction of the rotor shaft  34  of the turbomachine and the horizontal transverse direction  44  is transverse to the longitudinal direction of the rotor shaft  34 . 
     By the fixing means  20 , the turbomachine  2  is fixed, on its side facing the coupling  40 , at the bottom at the fixing point  30  in all horizontal directions  42 ,  44 , so that movement of the turbomachine  2  in all horizontal directions  42 ,  44  is prevented there. However, movement perpendicular to the horizontal directions  42 ,  44 , that is to say perpendicularly to the base  6 , is possible, so that the turbomachine  2  can participate in thermal expansion of the foot panels  12 ,  14  without stresses. 
     When the turbomachine  2  is in operation, it heats up, and therefore its housing  16  expands thermally. Expansion takes place in all three spatial directions. Since the turbomachine  2  is held by the turbomachine foot unit  4  from below only, the fixing of the turbomachine  2  on the base  6  generates no mechanical stresses in the turbomachine  2  in the vertical direction or perpendicularly to the base. However, as a result of the expansion of the turbomachine  2  in the horizontal directions  42 ,  44 , stresses would act upon the feet  8  if these were fixed firmly to the base  6 . 
     With only the horizontal directions  42 ,  44  being considered, the turbomachine  2  is fixed at the fixing point  30  by the fixing means  20 . This point on the turbomachine  2  is therefore stationary during all horizontal expansion movements. This is contrary to the feet  8  which are pushed away from the fixing point  30  as a result of thermal expansion of the turbomachine  2 . The two feet  8  adjacent to the fixing means  20  therefore move away from the fixing point  30  in the horizontal transverse direction  44  and, in the event of thermal contraction, toward the fixing point  30 . The two feet  8  located further away move about the fastening location  26  both in the horizontal longitudinal direction  42  and in the horizontal transverse direction  44 . The guide means  22  prevents movement of the turbomachine  2  in the guide region  32  in the horizontal transverse direction  44  and permits only the movement in the horizontal longitudinal direction  42 . As a result, a rotational movement of the turbomachine  2  about the fixing point  30  is prevented and therefore the mechanical load on the shaft  34  or coupling  40  is kept low. 
       FIG. 3  shows an alternative turbomachine foot unit  52 , without a turbomachine  2  placed on it, in a perspective illustration. The description of the following figures is restricted essentially to the differences with respect to the exemplary embodiment from  FIG. 1 , to which reference is made with regard to features and functions which remain the same. Components which essentially remain the same are basically designated by the same reference symbols and features not mentioned are adopted in the following exemplary embodiments, without being described again. 
     In contrast to the turbomachine foot unit  4 , the turbomachine foot unit  52  comprises foot panels  54  connecting two feet  8  to one another, and continuous transverse panels  56  which at their two outer ends likewise form foot panels welded to the foot panels  54 . The foot panels  54  and transverse panels  56  are themselves welded to the feet  8 . 
     In  FIG. 3 , recesses  58  in the foot plates  10  can be seen, which are set up in  FIG. 4  in a sectional view. The sleeves  24  are inserted into these recesses  58  for fastening the turbomachine foot unit  52  on the base  6 , the fastening means  60  designed in each case as a screw being led through said sleeves. The fastening means  60  is screwed to the base  6  and thus presses the sleeve  24  onto the base  6 . The pressure force may in this case be low. It is important merely to have fixing in the vertical direction. 
     The sleeve  24  comprises at its outer end a collar  62  which, on the one hand, forms a support for the screw head and, on the other hand, partially covers a shoulder  64  of the recess  58  and therefore lies inside the recess  58  on the foot plate  10 . The length  66  of the sleeve  24  from its lower end as far as the collar  62  is in this case selected such that it is equal to the thickness of the foot plate  10  from the base  6  as far as the shoulder  64 . By the sleeve  24  being braced on the base  6 , the foot plate  10  is also thus secured against movement in the vertical direction  68  away from the base  6 . However, the foot plate  10  is free in terms of its movement in the horizontal directions  42 ,  44 , insofar as the recess  58  is larger in its diameter by double the length  70  than the diameter of the sleeve  24  in its lower region or in the region of the collar  62 . By virtue of this play, all the foot plates  10  can be moved in both horizontal directions  42 ,  44  and in all horizontal directions lying between them, the feet  8  being horizontally movable independent of one another. 
     In this case, only the friction of the foot plate  10  on the base  6  and between the foot plate  10  and the collar  62  has to be overcome. To reduce this friction, a lubricant  72  for example in the form of a TEFLON® (PTFE)-ring or TEFLON® (PTFE)-film is introduced between the collar  62  and the shoulder  64  of the foot plate  10 . If the fastening means  60  fastens a foot  8  only to an intermediate plate  11  of the base  6  and horizontal movement between the intermediate plate  11  and foundation or ground is possible, the lubricant may be arranged between the intermediate plate  11  and ground or, in general, between two elements movable horizontally with respect to one another, one being fastened to the foot  8  and the other to the base  6 . 
       FIG. 5  shows a guide means  22  in the view in horizontal longitudinal direction  42  and  FIG. 6  shows a top view of that part of the guide means  22  which is fastened on the base  6 . A guide chock  76  is welded on a base plate  74  screwed to the base  6  or the intermediate plate  11  and has a shaped-out portion  78  which is of elongate form in the horizontal longitudinal direction  42 . A guide  80  welded to the housing  16  bears on both sides in the horizontal transverse direction  44  against this shaped-out portion  78  which forms a kind of guide rail, so that the guide  80  and, with it, the turbomachine  2  are prevented from movement in the horizontal transverse direction  44  in the guide region  32 . Movement in the horizontal longitudinal direction  42  is guided by the rail-like shaped-out portion  78 . 
     Similarly to  FIGS. 5 and 6 ,  FIGS. 7 and 8  show the fixing means  20  in a lateral illustration and in a top view. A bolt  82  is plugged into a recess in a guide  84  on the housing  16  and thus blocks movement of the turbomachine  2  at the fixing point  30  in all horizontal directions  42 ,  44 . However, as in the case of the guide means  22 , movement in the vertical direction  68  is maintained. Although rotational movement of the turbomachine  2  about the fixing point  30  is not blocked by the fixing means  20  on account of the rotationally symmetrical design of the bolt  82  and recess in the guide  84 , this rotational movement is nevertheless blocked by the guide means  22 , as described. 
       FIG. 9  shows a further exemplary embodiment having a turbomachine foot unit  86  with feet  88  in which a horizontal sliding plane between a foot  88  and a base  6  lies vertically level with a shaft of the turbomachine. For this purpose, the base comprises chocks  90  which raise the base  6  to this sliding plane and which can be stiffened in a stable manner with respect to one another in the horizontal direction. Center guidance by the fixing means  20  and guide means  22  is maintained. However, thermal expansion not only causes movement of the components of the turbomachine upward, but also uniformly upward from the machine axis, which lies in the middle of the machine shaft, and downward away from the feet  88  or the sliding plane between the feet  88  and base  6 . The machine shaft therefore remains in its position, both vertically and horizontally, and no appreciable error of alignment occurs due to thermal expansion.