US3805518A

US3805518A - Apparatus for controlling thermal growth in condensers

Info

Publication number: US3805518A
Application number: US00261895A
Authority: US
Inventors: K Kasschau; J Ward
Original assignee: Westinghouse Electric Corp
Current assignee: Westinghouse Electric Corp
Priority date: 1972-06-12
Filing date: 1972-06-12
Publication date: 1974-04-23
Anticipated expiration: 1991-04-23
Also published as: ES415791A1; NO136114C; JPS538006B2; GB1389997A; NO136114B; DE2329003A1; IT989063B; SE385240B; JPS4956012A

Abstract

A condenser shell structure having a trough formed by an inner wall spaced from the outer shell structure and extending upwardly from the condenser support plane to a region adjacent the flange connection with the exhaust duct of a steam turbine operable at variable exhaust temperature. The trough is continuously provided with condensate from the condenser hot well at approximately saturation temperature, thereby to maintain the condenser shell temperature at saturation temperature for the exhaust steam pressure with attendant minimization of thermal growth of the condenser shell. The turbine may thus be supported by the condenser with minimal movement of the turbine that could otherwise cause misalignment of associated gearing and coupling members.

Description

United States Patent 1191 Kasschau et a1.

1451 Apr. 23, 1974 APPARATUS FOR CONTROLLING THERMAL GROWTH IN CONDENSERS [75] inventors: Kenneth Kasschau, Los Altos; John W. Ward, Sunnyvale, both of Calif.

[7 3] Assignee: Westinghouse Electric Corporation,

Pittsburgh, Pa.

[22] Filed: June 12,-1972 [21] Appl. No.: 261,895

[52] U.S.Cl.....i .L 60/692 51 Int. Cl. Folk 9/00 [58] Field of Search 60/95 A [56] 7 References Cited 1 UNITED STATES PATENTS 1,781,108 11/1930 Grace 60/95 A UX 1,793,641 2/1931 Schmidt .Q 60/95 A X FOREIGN PATENTS OR APPLICATIONS 280,920 12/1914 Germany 60/95 A 395,581 5/1924 Germany- 1 60/95 A 549,433 4/1932 Germany ..1 60/95 A WATER OUT Primary Examiner-Edgar W. Geoghegan Assistant Examiner-H. Burks, Sr. Attorney, Agent, or FirmF. J. Baehr, Jr.

[57 ABSTRACT A condenser shell structure having a trough formed by an inner wall spaced from the outer shell structure and extending upwardly'from the condenser support plane to a region adjacent the flange connection with the exhaust duct of a steam turbine operable at variable exhaust temperature. The trough is continuously provided with condensate from the condenser hot well at approximately saturation temperature, thereby to maintain the condenser shell temperature at saturation temperature for the exhaust steam pressure with attendant minimization of thermal growth of the condenser shell.

The turbine may thus be supported by the condenser with minimal movement of the turbine that could otherwise cause misalignment of associated gearing and coupling members.

5 Claims, 5 Drawing Figures WATER l N TO STEAM GENERATOR FATENTEIWH /3 mm 31805518 xHI -EI 1 Hi 3 WATER TO STEAM GENERATOR WAT E R OUT pmm nm 23 mm A 34805 .51 8

sumaura T0 STEAM GENERATOR PIC-3.4

WATER OUT BACKGROUND OF THE INVENTION It has heretofore been the usual practice by the assignee of this invention, in the marine turbine art, to support the steam turbine on a base or pedestal structure and hang the steam condenser from the turbine. With this arrangement, temperature excursions of the condenser shell occasioned by the wide range of turbine exhaust temperature attained during operation, with attendant thermal growth, could have little if any effect on the turbine mounting position. Accordingly critical alignment of the turbine shaft with its associated gearing and coupling members could be maintained during such wide range of temperature.

However, marine turbine horsepower ratings are constantly increasing with attendant increase in size and weight of the turbine and the condenser. Supporting the heavier condenser is becoming a significant problem, particularly with respect to the interface connection between the turbine and the condenser.

Accordingly, it is desirable to mount the turbine on the condenser. However, such an arrangementcreates a difficult problem with regard to alignment of the turbine and its driving connection with the reduction gearing, since thermal growth of the condenser shell will inherently shift the turbine out of its axially aligned position with respect to the gearing and shaft coupling members.

SUMMARY OF THE INVENTION In accordance with the teachings of this invention, there is provided a marine turbine and condenser structure in which the turbine is mounted on the condenser shell and supported thereby. The condenser shell structure has an internal trough formed adjacent the condenser support plate and extending upwardly to a region adjacent its steam inlet flange, which inlet flange is connected to the steam exhaust structure flange of the turbine.

The trough is continuously provided with water during operation, and is maintained at'or near the saturation temperature for thesteam at the exhaust pressure. The shell of the condenser is thusheld at the temperature of the water by direct contact therewith. Thus, even though the turbine may be exhausting at a high temperature (as when driving in the astem direction) but at low pressure (due tototal heat load and condenser characteristics) the condenser shell temperature will be maintained substantially at the saturated steam temperature for the prevailing condenser pressure and will not be strongly influenced by the high temperature of the exhausting steam.

The water for the trough is preferably condensate from the condenser hot-well which is maintained near the saturation temperature for the prevailing low condenser pressure. Excess condensate is continuously drawn off, preferably by overflow conduit means and returned to the hot-well of the condenser. Hence, the overflow is prevented from falling onto the condenser tubes or being picked up by the high velocity of the incoming turbine exhaust steam.

DESCRIPTION OF THE DRAWINGS FIG. 1 is an end view of a steam turbine supported by a condenser having one embodiment of the invention incorporated therein, with portions cut away to show internal structure of the condenser;

FIG. 2 is a longitudinal view of the steam turbine shown in FIG. 1 with the condenser in cross-section;

FIG. 3 is an enlarged fragmentary view of the upper right-hand portion of the condenser, as viewed in FIG. 2,'to show details of the internal trough structure; and

FIGS. 4 and 5 are views similar to FIGS. 1 and 2 but showing another embodiment of the invention.

DETAILED DESCRIPTION OF HE PREFERRED EMBODIMENT Referring to the drawings in detail, FIGS. 1 and 2 show a first embodiment of the invention in which a steam' turbine is provided with a steam condenser 12 incorporating the invention. The turbine shown in the example is a marine propulsion turbine of the low pressure type, which, as well known in the art, is supplied by motive steam afterparti'al expansion in a high pressure turbine (not shown). The turbine 10 has an output shaft 14, which is drivingly connected to a ships propeller through reduction gearing by a suitable coupling (not shown). 1

The turbine 10 has a steam inlet 15 for driving the turbine shaft in the ahead mode, i.e., in a direction to propel the ship forward, and an alternately employed steam inlet 16 for driving the turbine shaft 14 in the astern mode, i.e., in a direction to propel the ship rearward.

The turbine 10 is of the condensing type, i.e., after the energy of the motive steam is dissipated by the turbine, the spent steam is directed through an exhaust outlet 18 into the condenser 12.

The condenser 12 is of the tube-and-shell type and includes a condenser outer shell structure 20 having a bundle of heat-exchange tubes 21 disposed therein and extending therethrough in a direction transverse to the axis A of the turbine 10. The tubes are received at their opposite ends in

suitable tube sheets

22 and 23 which together with

suitable channel heads

25 and 27 form respective inlet and

outlet water chambers

28 and 29 disposed in fluid communication with the tubes 21.

The channel head 25 is provided'with an inlet nozzle 30 and the channel head 27 'is provided with an outlet nozzle 31. Coolant water, from any suitable source (not shown) such as the sea is admitted to the inlet nozzle 30, from whence it flows into the inlet chamber 28 and thence through the tubes 21 to the outlet chamber 29. During its flow through the tubes 21, the coolant water removes heat from the turbine exhaust steam thereby condensing it. The thus heated coolant water is then directed from the outlet nozzle 31 back to the sea.

The condenser shell structure 20 is provided with a sump or hot-well portion 33 at its bottom end to collect the condensate, and an outlet conduit 34 is provided at the bottom of the hot-well 33 for removing the condensate from the condenser. A pump 35 of any suitable type is interposed in the outlet conduit 34 for pumping the condensate back to a suitable steam generator (not shown) for re.-vaporization.

As best shown in FIG. 2, the condenser 12 is disposed in an opening 36 in a-ships structure 37 and suspended therein in a support plane P-P extending through the upper portion of the outer shell 20 by a pair of condenser support structures 40. The condenser support structures 40 are disposed externally of the

outer shell walls

41 and 42 and each comprise a lower horizontal flange member 43, an upper horizontal flange member 44 and a plurality of spaced reinforcing gussets 45. The lower flange 43 bears on the upper surface of the ships structure 37 to support the condenser thereon, while the upper flange 44 bears on the bottom of the turbine casing flange 40 to support the turbine thereon.

With the above arrangement, the entire weight of the turbine 10 is supported by the portion of the outer shell structure 20 of the condenser lying between the lower flange 43 and the upper flange 44. Accordingly, the vertical position of the turbine shaft 14 is influenced considerably by the thermal expansion characteristics of the condenser outer shell structure during a heating period when the turbine 10 is in operation, taking as a point of reference, the at rest period when the turbine is notin operation and the temperature of the outer shell structure is at ambient temperature.

The critical portion of the outer shell structure 20 is that peripheral portion 47 lying between the upper and lower support flange members 44 and 43, respectively.

In accordance with the invention, in order to minimize the thermal growth of the outer shell portion 47, an inner wall structure 50 is connected to the outer wall member 42 by a bottom wall member 51, thereby providing an elongated open water passage or trough 52 communicating with the interior 53 of the condenser.

As best shown in FIGS. 1 and 3, a distribution plate 55 is attached to the outer wall 42 but is disposed in slightly spaced relation with the inner wall 50. If desired, the distribution plate 55 may be provided with a plurality of spaced perforations 56. The distribution plate is disposed in an intermediate position in the trough 52, and a flanged connector 57 inserted in the outer condenser shell 20 provides an inlet 58 for water into the trough 52 below the distribution plate 55, as will be subsequently described.

Also, to prevent entrance of highvelocity steam into the trough 52, an inclined baffle plate 60 is attached to the outer wall 42 and disposed in a manner toextend across the inner wall member 50. In the example shown and described above, the outer shell wall 42 is a planar member extending vertically. Hence, the inner wall'portion 50 is also planar and vertically disposed to impart a uniform cross-sectional shape to the trough 52.

However, the outer shell wall 41 has an upper portion 61 (FIG. 2) inclined inwardly at an angle of about 45. Accordingly, in this portion'an inner wall member 62 is provided with an inwardly inclined upper portion 63 conforming to the outer wall portion 61, thereby to provide an elongated trough 65 of uniform crosssectional shape in this portion of the condenser. Here again, an inclined baffle plate 66 (similar to baffle plate 60) is arranged to extend across the inner wall portion 63 to prevent admission of high velocity steam into the trough 65.

A second flanged connector 57a inserted in the outer wall 41 may be provided to admit water into the trough 65.

As best shown in FIG. 1, the opposite ends of the trough 52 are terminated and defined by a pair of

transverse wall members

67 and 68 connected at their bottom portion to the bottom plate 51 and at their upper portion to the peripheral shell portion 47.

The trough 65 is terminated at its ends in a manner similar to the trough 52 in a manner which is now clear and need not be shown.

The

inlet connectors

57 and 57a are connected by parallel conduits indicated by 70, 71 to the discharge end of the pump 35, so that in operation a part of the condensate usually returned to the steam generator is supplied to the

troughs

52 and 65.

In operation, as the vitiated steam from the turbine 10 is condensed in the condenser 12, it drops to the hot-well 33 where it is withdrawn through the conduit 34 by the pump 35 for delivery to the steam generator (not shown) for re-evaporation and returned to the turbine 10 as motive steam in a closed cycle, as well ment directly onto the surface of the condenser tubes 21 one or more overflow pipes 73 may be attached to the inner wall 50. And in a similar manner, one or more overflow pipes 74 may be attached to the the inner wall 62. The pipes 73 and 74 extend along the outer boundary: of the tube bundle B (FIG. 2) and downwardly therepast to direct such overflow directly to the hotwell 33. 1

Since the condensate from the hot well is constantly provided to the

troughs

52 and 65, and since this condensate is approximately at saturation temperature for the low pressure conditions in the condenser, the outer shell 20 of the condenser is maintained at the temperature of the condensate in the condenser regardless of the tem-perature of the exhaust steam before condensing. Thus, even when the turbine may be exhausting at a high tempera-ture (as when going astern) but at low pressure (due to total heat load) the condenser outer shell will be main-tained at the saturated steam temperature for the pressure. Accordingly thermally induced growth of the outer shell is minimized, at least in the region between the mounting plane P-P' and the turbine mounting flange 44, thereby substantially eliminating any movement of the turbine 10 that could otherwise cause misalignment of the turbine shaft 14 and its associated gearing and coupling members.

In FIGS. 4 and 5 there is shown another embodi-ment of the invention. This embodiment is generally simi-lar to the first embodiment described above. However, in this embodiment the turbine 10 is mounted upon and support-ed by a condenser 75 which, in turn is mounted upon-and supported at its bottom end by a foundation structure 77.

It will be noted that with this arrangement the entire outer shell structure 78 of the condenser 76 is disposed between the condenser mounting plane MP-MP' and the turbine exhaust flange 80. Accordingly the entire shell is susceptible to thermal growth, in operation, with attendant undesirable misaligning movement of the turbine.

In accordance with the invention, thermal growth of the outer shell 78 is minimized by provision of a pair of vertically elongated

trough structures

80 and 81 that extend from the hot-well 83 upwardly substantially to the condenser mounting flange 84.

As in the first embodiment, the

troughs

80 and 81 are disposed in transversely opposed relation (see FIG. 5) on opposite sides of the tube bundle 85 and defined by the

outer side walls

86, 87 of the condenser shell and inner spaced

walls

88, 89, respectively.

Accordingly, in this embodiment, the

troughs

80 and 81 hold a body of hot-well condensate that extends for substantially the entire vertical extent of the condenser

outer walls

86 and 87.

In all other respects, this embodiment may be similar to the first embodiment and need not be further described.

It will now be seen that the invention provides an arrangement in-which the outer shell structure of a steam condenser is prevented from overheating in an unpredictable manner and in which the thermal growth is controlled in operation to a predictable minimum degree of expansion.

It will further be seen that with the above arrangement, the turbine may be mounted upon the condenser and supported thereby, with full assurance that deleterious movement of the turbine, during a wide range of operation, is minimized.

It must further be pointed out that in both embodiments the troughs or water passages are on opposite sides of the tube bundle and substantially coextensive therewith. The end portions of the condenser outer shell structure do not necessarily require the trough treatment for two reasons, first, the coolant water in the channelheads and tubes provide an optimum heat sink for the adjacent portions of the condenser shell structure, and, second, the end portions of the shell are not normally in line between the shell support 17 or 37 and turbine 10, sothat thermal growth would not influence the turbine location.

We claim:

1. In combination, a steam turbine, a condenser for condensing steam exhausted from said turbine, said condenser having a shell structure and an exhaust structure connecting said condenser shell structure to said turbine, said turbine being adapted to exhaust steam to said condenser at varying temperatures, a condensate pump for removing condensate from said condenser, an upwardly extending inner wall joined to one of said structures to jointly form therewith a water wall in fluid communication with the interior of the condenser and with said condensate pump, and overflow means associated with said water wall, whereby condensate is circulated in said water wall to maintain the temperature of said one structure generally at a temperature equal to that of the condensate regardless of the temperature of the exhaust steam.

2. The combination recited in claim 1, wherein the condenser comprises a plurality of heat exchanger tubes for condensing the turbine exhaust steam, a hot well for collecting the condensate and means for directing condensate from said overflow means to said hot well.

3. The combination recited in claim 1, wherein the one structure is the exhaust structure.

4. The combination recited in claim 1, wherein the one structure is the condenser shell structure.

5. The combination recited in claim 1 and further comprising a distribution plate disposed in said water wall to distribute the condensate over the entire water wall.