ARRANGEMENT IN A BULB GENERATOR

Abstract: The present invention relates to an arrangement in a bulb generator (G), comprising a generator housing (1, 10, 110, 210, 310, 410) arranged in a water flow for letting turbine water flow therealong and towards the turbine (4), which arrangement comprises means for removing surplus heat generated during operation of the generator, which means comprise elements which are assembled as flow channels for coolant and/or heated generator air for indirect or direct cooling of the generator air, and for the purpose of providing a cooling system which to a large degree is independent of the quality of the river water or turbine water, and which also comprises elements which are non-costly as regards manufacturing and assembly, it is according to the present invention suggested that said means (111; 411) comprise, as known per se, extruded elements, especially elements which either comprise channels or by assembly define channels (112; 412) for circulating coolant, especially circulating air, or any other appropriate coolant, and that an outer surface of the extruded elements is exposed to bypassing turbine water.

Description: ARRANGEMENT IN A BULB GENERATOR Filed of the invention The present invention relates to an improved arrangement in a bulb generator, comprising a generator housing ar¬ ranged in a water flow which flows therealong and towards the turbine, which arrangement comprises means for remov¬ ing surplus heat generated during operation of the gene- rator, which means comprise elements which are assembled as flow channels for coolant and/or heated generator air for indirect or direct cooling of the generator air. Prior Art A known technique for cooling bulb generators comprises water/air-heat exchangers located in the generator hous¬ ing or bulb, the water being supplied from outside via pipes down the access shaft of the generator. Such an arrangement is often hampered with problems, inter alia because filters are required due to the quality of the river water. It has also been suggested to use the bulb wall as a heat exchanger in order to avoid said problems. In such an arrangement the bulb wall is made double in the conical part of the nose portion, such that there is provided a water/water exchanger ("double skin cooler") . The water in the intermediate spacing is circulated by means of pumps through the conventional water/air exchangers. Even if such a prior art system may operate well, it is hamp¬ ered with certain weaknesses especially as regards costly extra expenditures including comprehensive welding work, expensive materials, etc., the heat resistance through the bulb wall being relatively large. The requirement for necessary cooling surface will therefor influence the dimensions of the nose portion of the bulb or generator housing. NO 155.305 (SA Alsthom-Atlantique) refers to an immersed apparatus encapsuled in a housing, wherein the outer cooling takes place by means of cooling pipes through which are circulated cooling air, which cooling pipes are provided on the outside of the generator housing in order to allow cooling of the coolant gas by means of the water flowing through the water channel. US 4.524.285 (Rauch) refers to a hydro dynamic device, comprising a first pipe-shaped housing, a second housing having a conical front portion provided inside the first housing, and holding an electrical generator, as well as a third housing being designed with a conical portion opposite of that of the second housing. Through said first housing water is flowing along the outer surface of the second housing, which water is driving a turbine and contributes to the removal of heat generated by the gene- rator. US 5.333.680 (Sinhuber/Elin Energieversorgung GmbH) re¬ fers to a cooling system for a generator being installed in a chamber which is surrounded by flowing water, the walls of the chamber being manufactured from plate metal, and said walls of the chamber in the direction of the water flow being designed as a cooling radiator provided substantially as a double wall ("double jacket cooler") including channel-like cooling pockets wherein the secon- dary coolant can flow and by appropriate control be used for cooling the generator air. EP 0.581-841 (Reitinger/Elin Energieversorgung GmbH) relates to a bulb generator having separate cooled, sta- tic converting elements residing in the nose portion of the turbine housing, and being cooled indirectly by the water flowing therearound. US 3.936-681 refers to a cooling aggregate for an elec¬ trical generator, wherein is maintained an arched forward portion of the turbine housing, said arched outer wall being provided with a plurality of short hook-like cool- ing fins. The purpose of the short, hook-shaped cooling fins is to facilitate the adaption to the arched (non- contoured) portions of the bulb. Consequently, according to these publications it is not a token about preferably "longitudinal" and "straight" and double contoured extruded elements which are to be in¬ cluded as cooling elements in a bulb generator, i.e. especially by letting the outer surfaces comprise outer grooves having a favourable flow characteristics. NO 81.871 relates to elements in a heat exchanger of the plate type, wherein are suggested plates provided with corrugations, especially in order to render stiffness to the plates, said plates comprising both "large" corruga- tions and "small" corrugation running in parallel with the larger ones, all of which being provided for defining an inner hollow space having specific velocity and flow related changes for the liquid to flow between two such plates. According to this patent publication it is a token about preferably corrugated thin plates, manufac¬ tured by pressing, which hardly can be appropriate in the design of bulb turbines or generators. Thus, non of the mentioned publications give any instruc- tions about the use of extruded elements, especially elements of aluminium which have been assembled for, in connection with a bulb generator, giving combined outer and inner flow characteristics and heat exchanging pro¬ perties. Objects of the invention An object of the present invention is to provide an ar¬ rangement of the type as stated in the preamble, which both as regards cost and operation exhibits large advant¬ ages in relation to prior art. Further, an object of the present invention is to provide an arrangement wherein welding work and expensive materi- als are reduced to a minimum, whilst at the same time providing an arrangement having favourable cooling char¬ acteristics, and at the same time avoiding the disadvant¬ ages related to possible polluted river water. Summary of the invention The above objects are achieved in an arrangement in a bulb generator of the type as stated in the preamble, which according to the present invention is characterized in that said means comprise, as known per se, extruded elements, especially elements which either comprise chan¬ nels or by assembly define channels for circulating cool¬ ant, especially coolant air, or any other appropriate coolant, and that an outer surface of the extruded ele- ments is exposed to bypassing turbine water. An appropriate embodiment can be to the fact that said extruded elements are contoured preferably on both sides, such that said channels comprise inner protrusions in the form of cooling fins or ribs rendering a large heat con¬ ductions surface, and such that said elements on the outside define in the flow direction extending outer ribs or grooves for flow favourable surface contact with tur¬ bine water flowing therealong or thereabout. Such cooling elements having both outer and inner con¬ tours, may constitute a part of or substantially the overall front portion of the generator housing, said elements operating both as a flow guiding structure and heat exchanger. Alternatively, said elements may in assembled position constitute an individual flow capsule or a supporting device for said bulb generator, especially as a base or foundation, in any case appropriately located in relation to the generator water and in appropriate communication with the bulb generator. Further features and advantages of the present invention will appear from the following description taken in con¬ nection with the appended drawings, as well as from the appending patent claims. Brief disclosure of the drawings Fig. 1 is a schematical cross section through bulb type turbo generator, comprising previously known cooling technique. Fig. 2 is a perspective view of the front nose portion of a generator housing having a substantially smooth, double curved surface, according to known technique. Fig. 3 is a perspective view similar to Fig. 2, but wherein one or more parts of the generator housing repre¬ sent an example of an embodiment of an arrangement accor- ding to the invention. Fig. 4 is on a larger scale a section through the genera¬ tor housing illustrated in Fig. 3. Fig. 5 is a section as seen from above, through the upper part of the generator housing illustrated in Fig. 3 and Fig. 4. Fig. 6 is a perspective view similar to Fig. 2, but wherein a spesific nose portion is included in another example of an embodiment of an arrangement according to the invention. Fig. 7 is a section through the nose portion illustrated in Fig. 6. Fig. 8 is partly a front view and partly a section taken along the lines A-A in Fig. 7. Fig. 9 is a section taken along the line B-B in Fig. 7. Fig. 10 is a perspective view similar to Fig. 2, but wherein the nose portion is designed as still another example of an embodiment of an arrangement according to the present invention. Fig. 11 is a section on a larger scale through an embodi- ment of an extruded profile which appropriately may be included in an arrangement according to the invention. Fig. 12 illustrates an end view wherein a plurality of the profiles according to Fig. 11 are assembled to inner circulation channels including cooling fins protruding there into, said circulation channels defining outer ribs and grooves. Fig. 13 is a front view, partly in section, of a variant of an embodiment of an arrangement according to the in¬ vention, especially wherein the arrangement constitutes or is a part of one or more supporting devices for a generator housing. Fig. 14 and Fig. 15 are sections on a larger scale taken along the line A-A and the line B-B of Fig. 13, respec¬ tively. Fig. 16 illustrates on a somewhat larger scale a section through the main parts included in the embodiment illu¬ strated in Figures 13, 14 and 15. Fig. 17 is a section through an embodiment of an extruded profile which appropriately may be included in the ar¬ rangement according to Figures 14-16. Fig. 18 illustrates an end view wherein a plurality of the profiles according to Fig. 17 are assembled to inner circulation channels including cooling fins protruding thereinto, said circulation channels defining outer ribs and grooves. Detailed description of embodiments In Fig. 1 which illustrates a schematical section through a bulb type hydro generator G, the bulb or the generator housing itself is designated by reference numeral 1 , said generator housing 1 constituting the main member of a hydro generator which is located in a turbine pipe 2 wherethrough river water 3 or similar flows therealong and towards the turbine 4 provided downstreams in relat¬ ion to said generator housing 1. The hydro generator G illustrated in Fig. 1 , comprises a conventional technique for cooling said hydro generator, said generator comprising water/air heat exchangers 5 located down in the bulb, the water being supplied from outside via pipes 6 through the access shaft 7 of the generator. The cooling water itself is taken from the river water, which often requires filters due to the quality of the river water, which in turn makes the in¬ stallation of a river generator more expensive and com- plicated. In Fig. 2 there is perspectively illustrated a view of the front nose portion 1 OA of a generator housing 10 having a substantially smooth, double curved surface, which portion is designed double for thereby providing a water/water heat exchanger ("double skin cooler") . Here the water in the intermediate space may be circulated by means of pumps through the conventional water/air heat exchangers, for example of the type as discussed in con¬ nection with Fig. 1. Such double curved surfaces have hitherto been made of steel, and the surfaces are pro- vided by welding more or less double curved spherical elements, which involves substantial welding work. At the top the generator housing 10 is provided with an access shaft 17, and at the bottom with a foundation 18. In Figures 3, 4, and 5 there are illustrated details of an example of an embodiment of an arrangement according to the invention, wherein the coolant, especially coolant air, is passed through means giving direct heat exchange with turbine water flowing therearound. In Fig. 3 it is perspectively illustrated a generator housing 110 having a nose portion 11OA which still have substantially the same design as the nose portion 1OA as illustrated in Fig. 2, but wherein around an upper access shaft 117 and a pedestal or foundation 118 there have been constructed means functioning both as an outer flow guiding structure and an inner heat exchanger. In other words, around the upper access shaft 117 there have been included cooling means 110a and 110b, respec¬ tively, which individually comprises elements, especially elements 111 which either can comprise channels or by assembly define channels 112a and 112b, respectively, for circulating coolant, especially coolant air, or any other appropriate coolant, for example elements of the type illustrated in Figures 11 and 12. In the latter Figures it is also illustrated how such channels 112a, 112b com¬ prise inner protrusions in the form of cooling fins or ribs 113 rendering a large heat conductance surface. Further, from Fig. 3 it appears that said cooling means 110a and 110b are designed so as to outwardly defining outer ribs and grooves 115 extending in the flow dire¬ ction for flow favourable surface contact with turbine water flowing therealong or thereabout, as this is also illustrated in detail in Figures 11 and 12. Further, it appears from Fig. 4 and 5 that the elements which are included in the cooling means 110a and 110b around the access shaft 117 and the foundation 118, re- spectively, can allow cooling air to be undisturbedly excited at the one peripheral side of the generator 140, and thereafter be turned into the channels 112a of the cooling means comprising said elements 110a and 110b, respectively, wherefrom the cooled circulated air, see the arrows D and E, can be returned to the central port¬ ion of the generator. Since the profile elements included in the respective cooling means 110a and 110b preferably are constituted by straight parallel plate portions extending in the flow direction, which upstreams merge into the curved plate portions 141' and 142', respectively, there is achieved a flow picture which to a large degree can be compared with the flow picture which is illustrated in Fig. 2, wherein conventional design methods are used. It is to be understood that the material from which the cooling means 110a, 110b are made, should have favourable characteristics as regards thermal conductivity as well as favourable durability against corrosion, at the same time as the material can be manufactured in a simple manner by extrusion, for example aluminium, plastic or appropriate alloys or mixtures of other materials. In figures 6-9 there are illustrated details in connect¬ ion with a further example of an embodiment of an ar- rangement according to the invention, wherein the cool¬ ant, especially circulating air and/or bearing oil can be passed through means which render direct heat exchange with turbine water flowing therearound. In the embodiment according to Figures 6-9 said means rendering direct heat exchange with turbine water flowing therearound, may constitute substantially the overall front portion of the generator housing, said means func¬ tioning both as a flow guiding structure and a heat ex- changer. It is to be understood that said means can be build eit¬ her as a self supporting structure or said means can be assembled with outer supporting means, for example foun- dations and/or access shafts. In Fig. 6 there is perspectively illustrated a hydro generator housing 210 having a nose portion 210A which is included in an example of an embodiment of an arrangement according to the invention, said nose portion being de¬ signed from extruded elements, especially extruded alu¬ minium profiles, for example also here of the embodiment as illustrated in Figures 11 and 12, but here designated 211. In Figures 6-9 which illustrate details of a nose portion 210A constituting another embodiment of an arrangement according to the invention, it is especially in Fig. 9 seen how the circulating air in the form of arrows 216 is guided through the inner channels 212 from various gene¬ rator parts 217, and via fans 218 back to the machine room 219. It is to be understood that the circulated air 216 can be used for direct cooling of generator parts 217, and that the circulated air also can operate as a heat exchanger as regard cooling of bearing oil. As specifically illustrated in Fig. 6 and Fig. 9 the nose portion 21OA of the generator may be designed with a wedge-shaped structure, similar to a straight ship bow, but it is to be understood that the wedge-shaped struc- ture also can be bent or buckled in the form of two or more straight surfaces on each side, for thereby achiev¬ ing an appropriate flow guidance of the river water. In Fig. 10 there is illustrated yet another example of an embodiment, wherein is illustrated a hydro generator 310 having a nose portion 31 OA comprising extruded elements 311, spaced around said nose portion 310A. Also here the elements 311 are designed as straight elements in the flow direction, which elements appropriately merging with a curved forward nose portion 31OB and further curved portions 31OC between said elements 311. Also here the elements may be designed as discussed in connection with Figures 11 and 12. As previously described it is in connection with Figures I I and 12 illustrated an example of an individual profile III and a double profile 111a, 111b, said two elements 111a, 111b being of the type illustrated in Fig. 12, and being assembled to define inner circulating channels 112, or 112a, 112b, for circulating air, at the same time as cooling fins 113 protrude into the channels, and at the same time as said circulating channels 112 define outer ribs 114 with grooves or recesses 115 provided therebe¬ tween. The inner cooling fins 113 will, as previously discussed, render a large heat conductance surface, and the alternating outer ribs 114 and tracks 115 will render large contact surface with the river water flowing there- around . It is to be understood that the arrangement according to the invention may comprise cooling means, appropriately designed as substantially extruded elements, which in assembled position define an individual flow capsule or define a supporting devise for the bulb generator, espe¬ cially as a base or foundation, in both cases located in the water flow outside the bulb, and at the same time in appropriate communication with the bulb generator with its coolant, especially purified cooling water or any other appropriate coolant. In Figures 13-15 there is illustrated an embodiment of an arrangement according to the invention wherein the ar¬ rangement constitutes or is included as a part of an upper supporting device 410a and a lower support device 410b for a generator housing 410, comprising extruded elements 411. Fig. 16 illustrates on a larger scale a section through the main elements included in the embodiment illustrated in Figures 13, 14 and 15. Fig. 17 is section through an embodiment of an extruded profile which appropriately may be included in the ar¬ rangement according to Figures 13-15. Fig. 18 illustrates an end view wherein a plurality of the profiles according to Fig. 17 have been assembled to inner circulating channels having cooling fins protruding thereinto, said circulating channels defining outer ribs and grooves. Also here the cooling means 410a, 410b have been designed from extruded elements, said elements 411 on the one side comprising cooling fins 413 and on the other side com- prising cooling ribs 414. By assembling a plurality of such elements 411 such elements will assembled in pairs define inner channels 412 having a series of inner cool¬ ing ribs 413 for coolant, especially purified water, at the same time as the assembled channels 412 on the out¬ side define rib-shaped cooling surfaces 414 in the form of grooves 415 provided with fins exposed to the bypassing turbine water. In addition to the protruding "inner" cooling fins 413 there are at certain distances provided combined spacing and supporting fins 420 which by an axial turning of the elements 180° in relation to each other provide pairs of self-supporting channel-shaped elements, which will rend- er the subsequent welding work more easy.

Claims: P a t e n t c l a i m s 1. Arrangement in a bulb generator (G), comprising a generator housing (1, 10, 110, 210, 310, 410) arranged in a water flow for letting turbine water flow therealong and towards the turbine (4), which arrangement comprises means for removing surplus heat generated during ope¬ ration of the generator, which means comprise elements which are assembled as flow channels for coolant and/or heated generator air for indirect or direct cooling of the generator air, c h a r a c t e r i z e d i n that said means (111; 411) comprise, as known per se, extruded elements, espe¬ cially elements which either comprise channels or by assembly define channels (112; 412) for circulating cool¬ ant, especially circulating air, or any other appropriate coolant, and that an outer surface of the extruded ele¬ ments is exposed to bypassing turbine water. 2. Arrangement as claimed in claim 1, c h a r a c t e r i z e d i n that said extruded ele¬ ments are contoured preferably on both sides, such that said channels (112; 412) comprise inner protrusions in the form of cooling fins (113; 413) or ribs rendering a large heat conductance surface, and such that said ele¬ ments on the outside define outer ribs or grooves (114; 414) extending in the flow direction for flow favourable surface contact with turbine water flowing therealong or thereabout. 3. Arrangement as claimed in claim 1 or 2, c h a r a c t e r i z e d i n that said cooling means comprise extruded preferably plate-shaped elements (111; 412) provided with larger or less rib-shaped protrusions (113; 413) on both side of said plates, whereby said plate-shaped elements (111; 412) by assembly in pairs define inner channels (112; 412) with cooling ribs (113; 413) for coolant, especially purified water, and defining outer cooling surfaces (114, 115; 414, 415) provided with ribs against bypassing turbine water. 4. Arrangement as claimed in claim 1 , c h a r a c t e r i z e d i n that said extruded ele¬ ments are provided as substantially longitudinal straight and double contoured plate-shaped elements, which plate- shaped elements are included as continuous straight ele- ments in the structural part of which they constitute a member. 5. Arrangement as claimed in claim 4, c h a r a c t e r i z e d i n that said straight plate-shaped elements are assembled with in upstream direction curved transfer portions (Fig. 3). 6. Arrangement as claimed in any of the preceding claims, c h a r a c t e r i z e d i n that the material of the cooling means has appropriate characteristics as regards thermal conductively and favourable durability against corrosion, for example aluminium, plastics or other ap¬ propriate alloys or mixtures. 7. Arrangement as claimed in any of the claims 1-6, c h a r a c t e r i z e d i n that said elements with both outer and inner contours constitute a part of or substantially the hole front portion (110A) of the gene- rator housing (110), said elements operating both as flow conducting structure and heat exchanger. 8. Arrangement as claimed in claim 7, c h a r a c t e r i z e d i n that the part of the generator housing which is made from said elements, is constructed around an upper access shaft (117) and/or around a lower pedestal (118) or foundation. 9. Arrangement as claimed in claim 8, c h a r a c t e r i z e d i n that the elements around the access shaft and the foundation are so adapted that the circulating air for the generator in the generator housing can be passed without obstruction out from the one peripheral side (140) of the generator and thereafter be guided into the cooling means (110a, 110b) comprising said elements, wherefrom the cooled circulating air can be returned to the central portion of the generator. 10. Arrangement as claimed in any of the claims 7 or 8, c h a r a c t e r i z e d i n that the profiled ele¬ ments are constituted by in the flow direction extending straight parallel plate portions (110a, 110b) which up- streams merge with curved plate portions (141', 142') without contouring. 11. Arrangement as claimed in any of the claims 8-10, c h a r a c t e r i z e d i n that the cooling means designed as base or foundation are located symmetrically in relation to access shafts for optimizing the flow picture. 12. Arrangement as claimed in any of the preceding claims, c h a r a c t e r i z e d i n that the coolant, es¬ pecially circulating air is driven by a certain over pressure. 13. Arrangement as claimed in any of the preceding claims, c h a r a c t e r i z e d i n that said means are constructed as a self-supporting structure. 14. Arrangement as claimed in claim 13, c h a r a c t e r i z e d i n that said arrangement comprises cooling means comprising substantially extruded elements which in mounted position define an individual flow capsule or a supporting device for said bulb gene¬ rator, especially a base or foundation, in both cases appropriately located in relation to the generator water and in appropriate communication with said bulb gene¬ rator. 15. Arrangement as claimed in claim 14, c h a r a c t e r i z e d i n that said coolant com- prises as known per se liquids or fluids having good heat conductance characteristics.

Inventors: GEVELT BJOERN, OFTEDAL KAARE OLAF, GEVELT, BJOERN, OFTEDAL, KAARE, OLAF
Applicants: ABB KRAFT AS, GEVELT BJOERN, OFTEDAL KAARE OLAF, ABB KRAFT A/S, GEVELT, BJOERN, OFTEDAL, KAARE, OLAF
Application year: 1996
Main classification: H02K9
IPC codes: F03B11, F03B13, H02K9