Abstract:
A regenerative heat exchanger, including a heat accumulator arranged as a rotor, rotatably held around a central rotational axis, and configured to transmit a heat of at least one gas volume flow passing through the rotor to another gas volume flow passing through the rotor, and including a sealing system for the rotor including at least one seal which is fixed in relation to the rotor, is pressed against the rotor, and is supported by a plurality of rollers on the rotatable rotor.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to foreign European Patent Application No. EP 10015001.0, filed on Nov. 25, 2010, the disclosure which is incorporated by reference in its entirety. 
       FIELD OF THE DISCLOSED SUBJECT MATTER 
       [0002]    The disclosed subject matter relates to a regenerative heat exchanger including a heat accumulator arranged as a rotor, rotatably held around a central rotational axis, and configured to transmit a heat of at least one gas volume flow passing through the rotor to another gas volume flow passing through the rotor. 
       BACKGROUND 
       [0003]    Regenerative heat exchangers of this kind are used for heat transmission from at least one gas volume flow to at least one other gas volume flow. A rotating heat accumulator, which is the so-called rotor, is heated in an alternating fashion by at least one gas volume flow and cooled again by at least one other gas volume flow, with thermal energy being transmitted from the one to the other gas volume flow. As a result, one of the gas volume flows can be heated and another gas volume flow can be cooled. The rotor comprises two face sides, an outside jacket and usually a segmented portion for accommodating the heat accumulator masses. The rotor is rotatably held around a central rotational axis, with said rotational axis preferably be aligned vertically. 
         [0004]    To seal the gas volume flows guided through the regenerative heat exchanger, a sealing system with core, radial, and/or circumferential seals is provided. The radial seals are arranged on the face sides of the rotor and are provided to prevent short-circuit volume flows between the gas volume flows. The circumferential seals are arranged on the face edges of the rotor and are provided to prevent leakage volume flows into the rotor housing or into the ambient environment. The seals are arranged in a stationary manner with respect to the rotating rotor. As a result of a permanent relative movement between the rotor and these seals and a continuously changing thermal expansion of the rotor and consequently resulting uneven rotor deformations, high demands are placed on the sealing system in order to achieve a low amount of losses (leakages) and thus a high level of efficiency. 
         [0005]    Various sealing systems are known from the state of the art, which enable a relatively small sealing gap in operation between the seal and the rotor. Reference is made in this respect for example to European Patent Application Publication Nos. EP 1 777 478 A1 and EP 2 177 855 A, the disclosures of each of which are incorporated by reference in their entireties. However, conventional sealing systems are frequently disproportionately complex and expensive in practice. 
       SUMMARY 
       [0006]    It is an object of the disclosed subject matter to provide a regenerative heat exchanger of the kind mentioned above with a simple and effective sealing system. 
         [0007]    This object is achieved by a regenerative heat exchanger in embodiments incorporating the features of claim  1 . Other aspects of embodiments of the disclosed subject matter are recited in the dependent claims. 
         [0008]    In an embodiment of the disclosed subject matter, the sealing system for the rotor comprises at least one seal which is fixed in relation to the rotor and which is pressed against the rotor or a component belonging to the rotor (e.g. by effective weight, spring cylinders, actuators and the like) and which is supported by a plurality of rollers on the rotatable rotor or on a component belonging to the rotor, thereby being provided with forced guidance predominantly in the axial direction. This means that the respective seal is quasi subject to forced guidance, which leads in operation to the consequence that the respective seal continuously follows the thermally induced rotor deformation at a constant distance which is predetermined by the rollers, as a result of which a small and constant sealing gap is ensured. 
         [0009]    In accordance with the disclosed subject matter, minimal sealing gaps can be realized with a comparatively low amount of constructional effort, so that short-circuit and/or leakage volume flows will occur to an exceptionally low extent. In the case of regenerative heat exchangers with suction, the gas quantity to be removed will be reduced. Similarly, the sealing gas quantity will be reduced when using sealing gas. Moreover, the disclosed subject matter has proven to be very beneficial to mounting and offers simple handling and maintenance. It is a further advantage that it is possible to omit the electromechanical and mostly sensor-controlled adjusting devices for the seals which are included in many conventional designs. 
         [0010]    In another embodiment of the disclosed subject matter, it is preferably provided that the rollers are arranged in the fixed seal and/or are fastened to the fixed seal. The rollers can be held with a shaft on the seal or a component belonging to the seal. In another embodiment, it is further preferably provided that the rollers will roll off on at least one corresponding running or rolling surface on the rotor or a component belonging to the rotor, or are guided between two corresponding rolling surfaces which are axially spaced from one another. These rolling surfaces can be especially arranged on exchangeable wearing plates which are fastened to the rotor (a rotor body or a component belonging to the rotor). Similarly, a reverse arrangement of rollers and running surfaces can be provided. 
         [0011]    In order to ensure a minimal sealing gap, especially in critical regions in which the seal is pressed against the rotor (actuating points), the individual rollers may be arranged at least in the region and especially only in the region of the actuating points or pressing points of the seal against the rotor. 
         [0012]    The seal which is supported by means of the rollers is preferably a radial seal. The seal which is supported by means of the rollers is especially a circumferential seal. It is also possible to simultaneously support both the radial seals and also the circumferential seals at least on one rotor side by means of rollers on the rotating rotor. 
         [0013]    In another embodiment there is at least one circumferential seal which is supported by means of rollers on the rotor and is coupled with a radial seal on the same rotor side, such that the respective radial seal is co-moved during the axial movement of the circumferential seal in the axial direction. For this purpose, the radial seal is movably arranged in the axial direction. The coupling between the circumferential seal and the radial seal may occur via a mechanical actuating mechanism, which transmits axial movements of the circumferential seal via at least one actuating bar or the like onto the respective radial seal. The sealing system on one rotor side can therefore perform movements which follow the rotor movements in the axial direction. The preferably radially extending actuating bar is ideally arranged in the rotor housing of the regenerative heat exchanger, namely between the respective radial seal and the wall of the housing, wherein a sealing sleeve can also be arranged in this area. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    The invention will be explained in closer detail by reference to embodiments shown in the drawings, which show the following in the schematic partial sectional views: 
           [0015]      FIG. 1  illustrates a first embodiment of a regenerative heat exchanger; 
           [0016]      FIG. 2  illustrates a second embodiment of a regenerative heat exchanger; 
           [0017]      FIG. 3  illustrates a third embodiment of a regenerative heat exchanger, and 
           [0018]      FIG. 4  illustrates a fourth embodiment of a regenerative heat exchanger. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]      FIG. 1  illustrates a regenerative heat exchanger, designated with reference numeral  1 , of which only one symmetrical half is illustrated. The regenerative heat exchanger  1  comprises a rotor  2  which is rotatably held around a vertical rotational axis A and is arranged in a rotor housing  3 . Several gas volume flows flow through the rotor  2 , with heat from at least one gas volume flow being transmitted to at least one other gas volume flow. A sealing system with radial seals  4  and circumferential seals  5  is provided for sealing the gas volume flows V guided through the regenerative heat exchanger  1 . The radial seals  4  are arranged on the face sides of the rotor  2  and are provided to prevent short-circuit volume flows between the gas volume flows V. The circumferential seals  5  are arranged on the face edges of the rotor  2  and are provided to prevent leakage volume flows into the rotor housing  3 . The radial seals  4  and the circumferential seals  5  are arranged in a stationary manner with respect to the rotating rotor  2 . The radial seals  4  and the circumferential seals  5  preferably form an inherently closed sealing frame, together with optional core seals (not illustrated). The seals which are arranged on the upper face side and on the bottom face side of the rotor  2  are arranged in a substantially identical manner. Unless stated otherwise, the following explanations relate by way of example only to the upper seals and apply analogously to the bottom seals. 
         [0020]    The upper radial seal  4  is arranged as a sealing plate and is fastened to or suspended on the rotor housing  3  by means of several equally spaced actuating members or spring cylinders  7 ,  8  and  9 . (The bottom radial seal  4  is supported respectively by spring cylinders or the like.) Each spring cylinder  7 ,  8  or  9  represents an actuating point for the radial seal  4 . It is also possible to use counterweights instead of the spring cylinder  7 ,  8  and  9 . The radial seal  4  is arranged in the regional direction with joints  41  and  42  which subdivide radial seal  4  into several sections. The radial seal  4  is thereby able to adjust to thermally induced rotor deformations. It is alternatively possible to arrange the radial seal  4  without joints and in a flexible way. There is a sealing gap S with the smallest possible size of the gap between the radial seal  4  and the upper face side of the rotor  2 . A sealing or expansion sleeve (see reference numeral  10  in the bottom region of the heat exchanger) can be arranged between the radial seal  4  and the wall of the rotor housing  3 , which sleeve will compensate the relative movements of the middle seal in relation to the wall the housing. 
         [0021]    The circumferential seal  5  is arranged as an annulus-shaped sealing frame and is fastened to or suspended on the rotor housing  3  with several actuating members or spring cylinders  11  which are evenly distributed in the circumferential direction. The circumferential seal  5  can be provided with segments or joints, or be arranged in a joint-free and flexible way. In the illustrated embodiment, the circumferential seal  5  or the sealing frame provides sealing against a rotor flange  6  which protrudes radially to the outside from the rotor body. There is also a sealing gap with the smallest possible size of the gap between the circumferential seal  5  and the rotor flange  6  of the rotor  2 . Each spring cylinder  11  represents an actuating point for the circumferential seal  5 , with the circumferential seal  5  being pressed against the rotor flange  6  by means of excess weight (weight less actuating force in the spring cylinders  11 ). 
         [0022]    In order to ensure a defined sealing gap between the circumferential seal  5  and the rotor flange  6  irrespective of thermally induced rotor deformations, the circumferential seal  5  is supported by means of a plurality of rollers  12  on the rotor flange  6  which belongs to the rotor  2 . A roller  12  is preferably provided at least in the region of every single actuating point. As a result, the circumferential seal always maintains a constant distance from the rotor flange  6  in operation and simultaneously at least follows the axial rotor deformations. 
         [0023]    In the embodiment illustrated in  FIG. 1 , the rollers  12  are arranged in a recess in the circumferential direction  5  and are preferably also rotatably held therein (e.g., by means of a shaft). During the rotation of the rotor  2 , the rollers  12  will roll off on a wearing plate  14  which is fastened to the rotor flange  6 . Preferably, the wearing plate  14  is provided with a segmented configuration in the circumferential direction. Such a wearing plate can also be provided on a corresponding rolling surface in the circumferential seal  5 . It is also possible that the rollers  12  are guided in the manner of a sandwich between two wearing plates which are spaced from one another in the axial direction a. Notice should generally be taken when configuring and/or adjusting the spring cylinders  11  (and optionally also counterweights, if they are used) that the pressing pressure between the rollers  12  and the corresponding rolling surfaces is kept at a low level. This is achieved for example in such a way that the upper spring cylinders  11  substantially absorb or at least reduce the weight load of the circumferential seal  5 . 
         [0024]    In the embodiment illustrated in  FIG. 1 , a mechanical coupling of the radial seals  4  with the circumferential seals  5  is provided both on the upper face side and also on the bottom face side of the rotor  2 , for which purpose the circumferential seals  5  and the radial seals  4  are frictionally connected with one another. As a result, the radial seals  4  will follow the forcibly guided movements of the circumferential seals  5  in the axial direction a, for which purpose the radial seals  4  are movably held in the axial direction a. Sealing of the rotor  2  is considerably increased thereby and leakages are considerably reduced. 
         [0025]      FIG. 2  illustrates a second embodiment in which the rollers  12  fastened to the circumferential seal  5  are guided between two axially spaced rotor flanges  61  and  62  with respective rolling surfaces. This enables a “direct” forced guidance for the circumferential seal  5 . In all other respects the explanations made in connection with the first embodiment illustrated in  FIG. 1  shall apply. 
         [0026]    The third embodiment illustrated in  FIG. 3  also comprises a mechanical coupling of the circumferential seals  5  with the radial seals  4 . For this purpose, the circumferential seals  5  are respectively connected with a radially extending actuating bar  16 , which causes an adjustment of the respective radial seal  4  (on the same rotor side) in the axial direction a via several actuating members  17 . As a result, the forcibly guided movement of a circumferential seal  5  is transmitted according to the lever ratios onto the respective radial seal  4  or its individual sections, for which purpose the radial seals  4  are movably held in the axial direction a or are also arranged in a flexible way for example. The radially extending actuating bars  16  are arranged in the interior of the rotor housing  3 . In some embodiments, the actuating bars  16  can also be arranged outside of the housing  3 . 
         [0027]      FIG. 4  illustrates a fourth embodiment in which the radial seals  4  are also supported by means of rollers  18  on the face sides of the rotor  2 . As a result, the radial seals  4  can be forcibly guided in operation at a constant distance from the face sides of the rotor  2  and can continuously follow the axial rotor deformations. The rollers  18  are arranged in the region of the actuating points or spring cylinders  7 ,  8  and  9 . Corresponding rolling surfaces are arranged on face sides of the rotor  2 . These rolling surfaces can be arranged on wearing plates  19 , as illustrated, by way of example, for the bottom, radial inner roller  18 . 
         [0028]    It is expressly understood that the features of the embodiments explained above in connection with the drawings can be combined with one another insofar as this does not lead to any technical inconsistency.