US3338052A

US3338052A - High recovery condenser

Info

Publication number: US3338052A
Application number: US502187A
Authority: US
Inventors: Paul C Holden
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1965-10-22
Filing date: 1965-10-22
Publication date: 1967-08-29
Anticipated expiration: 1984-08-29

Description

Aug. 29, 1967 P, c. HOLDEN 3,338,052

HIGH RECOVERY CONDENSER Filed Oct. 22, 1965 v 5 Sheets-Sheet l PRESSURE 1 LENGTH ALONG TURBINE AXIS g3 |NvENToR Poul C. Holden Aug- 29, 1967 P. c. HOLDEN 3,338,052

HIGH RECOVERY CONDENSER Filed Oct. 22, 1965 .3 Sheets-Sheet 2 Aug. 29, 1967 P. c. HOLDEN HIGH RECOVERY CONDENSER 5' Shee ts-Sheet Filed Oct. 22, 1965 United States Patent O 3,338,052 HIGH RECOVERY CONDENSER Paul C. Holden, Newtown Square, Pa., assignor to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Oct. 22, 1965, Ser. No. 502,187 Claims. (Cl. 60-95) This invention relates to apparatus for condensing vapor, more particularly to vapor condensing apparatus of the surface type, and has for an object to provide improved apparatus of this type.

One of the main objects of this invention is to provide a surface type vapor condenser in which vapor admitted at high velocity for condensation is rapidly yet effectively reduced in velocity to promote condensation of the vapor by heat exchange in a more eiiicient manner than heretofore.

Another object is to provide a vapor condenser of the above type in which high velocity vapor admitted thereto for condensation is preliminarily' rapidly dilused in a steam lane and in which the boundary layer flow formed during diiiusion is continuously removed from the vapor lane by entrainment with the vapor as it ows into the tube field for condensation.

It has been found from tests of double opposed-dow steam turbine models that the pattern of the steam flow leaving the turbine exhaust hood and entering the steam condenser has large ow concentrations at the ends of the turbine. This phenomenon produces high velocity cores having a total pressure substantially higher than the nominal condenser pressure and spaced from each other by a lowertotal pressure region. Accordingly, much of the velocity energy of the cores is dissipated in large eddies formed in the lower pressure region with attendant undesirable increase in the average pressure level of the entire condenser. As well understood in the art, this effect increases the heat rejection to the heat sink and reduces the power output of the turbine.

In accordance with the invention, there is provided an arrangement for recovering the high velocity energy of the above steam flow cores, thereby to reduce the average operating pressure level of the condenser.

Briefiy, there is 'provided a surface condenser in which at least the upstream peripheral portion of the tube ield is arranged t-o provide a vapor lane for the incoming vapor lto be condensed that is of divergent shape, i.e., of increasing cross-sectional area in the direction of flow of the vapor. Accordingly, as the initially high velocity vapor flows through the vapor lane, at least a portion of the high velocity head is converted to pressure with attendant low velocity by diffusion which assures that subsequent turning losses of the vapor, as it is drawn into the tube field for condensation, are minimized.

To facilitate the formation of the divergent vapor lane portion, the tubes are disposed normal to the axis of rotation of the turbine with which the condenser is employed, and where the turbine is of the double opposedow type with axially spaced exhaust hoods, the axially opposed peripheral portions of the condenser tube eld are symmetrically arranged to form a diffusing vapor lane for each of the vapor ow streams from the turbine exhausts.

A high rate of diffusion is eiciently and readily attained with the invention by spacing the tubes with relation to each other, thereby forming spaces in communication with the vapor lane, which spaces are effective to withdraw the relatively slow moving boundary layer vapor before appreciable accumulation.

The above and other objects, are effected by the invention as will be apparent from the following descrip- ICC tion and -claims taken in connection with the accompanying drawings, forming a part of this application, in which: FIGURE 1 is a diagrammatic longitudinal sectional view of a double opposed-flow condensing steam turbine, illustrating typical exhaust steam flow conditions;

FIG. 2 is a chart comparing the exhaust steam pressure distribution attained with the invention and With l the turbine arrangement shown in FIG. l;

FIG. 3 is a longitudinal sectional view of a steam condenser formed in accordance with the invention;

FIG. 4 is a transverse sectional view taken on line IV-IV of FIG. 3; and

FIG. 5 is a view similar to FIG. 4, modification of the invention.

Referring to the dra-wings in detail, in FIG. 1 there is shown in highly diagrammatic form, a condensing steam turbine 10 of the well-known double opposed-How type comprising identical left and right-hand steam expansion sections 11 and 12 carried by a shaft 13 comm-on to both expansion sections, and disposed within a common shell structure 14. The shell 14 is provided with the usual centrally disposed steam inlet 15 and a pair of Iaxially opposed exhaust hoods 16 and 17 having downwardly extending steam outlets 18 and 19.

The outlets 18 and 19 are provided with an external peripheral flange 20 that is attached to the inlet neck portion 21 of a conventional surface condenser (not shown) so that, in operation, steam admitted to the turbine through the inlet 1S liows to the left through the expansion section 11 and to the right through the expansion section 12 and is exhausted from the turbine hoods 16 and 17 in two axially spaced and downwardly directed streams through the outlets 18 and 19 into the common condenser neck portion 21, as indicated by the arrows 23 and 24.

The two exhaust steam streams 23 and 24 are substantially identical and form cores 18a and 19a of high velocity in the axially opposed end regions 25 and 26 of the condenser neck portion.

If the high velocity cores 18a and 19a are permitted to diffuse in the condenser neck portion, much of the velocity energy present in the cores Will be dissipated in large eddies 28 and 29 formed in the low velocity region 30 of the neck portion intermediate the end regions 25 and 26.

The above conditions are indicated graphically in the chart shown in FIG. 2, wherein there is shown a typical total pressure distribution curve 31 having high absolute pressure portions 32 and 33 corresponding to the end regions 25 and 26 and a substantially lower absolute pressure central portion 34 corresponding to the intermediate region 30. It will be noted that the central curve portion 34 lies adjacent a dotted horizontal pressure line 35 indicating static pressure, while the end curve portions 32 and 33 lie considerably above the static pressure line 35. Accordingly, the portions of the curve 31 above the static pressure line (portions 32 and 33) indicate the velocity components of the cores 18a and 19a, since total pressure as well understood in the art is a summation of static pressure and dynamic pressure and dynamic pressure is a measure of velocity energy of a fluid.

In accordance with the invention, as best shown in FIGS. 3 and 4, there is shown a steam turbine 37 of the same type as the turbine 10 described in conjunction with FIG. l and provided with a surface condenser 38 adapted to receive the exhaust steam from the steam turbine, in which the losses due to eddie currents 28 and 29 (FIG. 1) are substantially minimized and the velocity energy of the high velocity steam cores 18a and 19a is su-bstantially recovered.

The condenser 38 is provided with a bundle or group but illustrating a of closely spaced parallel tubes 39, hereinafter termed a tube field, having their end portions received in a pair of tube sheets 40 and 41 and disposed within a shell or housing 42 deiining a chamber 42a. The upper part of the housing 42 is provided with an exhaust steam inlet or neck portion 43 communicating with the chamber 42a and having a peripheral ange portion 44 attached to a mating flange 45 provided in the exhaust hood 46 of the steam turbine 37. The exhaust hood 46 corresponds to the exhaust hood 17 in FIG. l.

At each end of the condenser 38 there is provided water box structure 48 and 49 associated with the tube sheets 40 and 41, respectively, the water box 48 being the inlet box and having a water inlet 50 and the water box 49 :being the outlet box and having a water outlet 51.

The tube field 39 is disposed in the chamber 42a and in operation is externally traversed by steam and internally traversed by coolant water owing in one pass from left to right, as viewed in FIG. 3, from the inlet box 48 to the outlet box 49. The tube eld 39 is supported at spaced intervals along its length by suitable support plates 52, which in turn are anchored to the condenser housing 42 by mounting lugs 53.

The central region of the tube iield is devoid of tubes and the support plates 52 are provided with central openings 54, thereby forming a central air collection space 55 extending substantially the entire length of the tube field.

An air offtake pipe 56 extends lengthwise through the air collection space and is provided with a plurality of apertures 57 communicating with the space. This pipe is extended through one of the water boxes, for example the inlet box 48, and is connected to a suitable source of suction (not shown).

The lower portion of the condenser housing 42 is provided with a depending well portion 58 communicating with the chamber 42a for collecting the condensate, and a condensate outlet 59 is provided for removing the condensate from the condenser.

As thus far described the condenser is substantially conventional. In accordance with the aspects of the invention, the tube field 39 is arranged to extend in a direction normal to the axis .of rotation R of the turbine 37, as shown in FIG. 3, and the condenser neck portion 43 is flared downwardly and outwardly to provide a distribution region 60 for the exhaust steam from the turbine hood 46.

Y As best shown in FIG. 4, the tube field 39 is of smaller cross-sectional area than that of the condenser housing and is disposed in a central position therein. The tube iield 39 is symmetrical with respect to its vertical axis and jointly with the side walls 62 and 63 ofthe condenser housing forms a pair of vertically extending steam lanes 64 and 65 communicating with the steam distribution region 60.

The right-hand steam lane 65 is bounded and thus dened on the left by the tubes 66 disposed in the outer periphery of the tube field 39. The periphery of the tube iield defining the left side of the right-hand lane 65 is arranged to provide a divergent portion 67 adjacent the inlet 68, at the upstream end of the lane with respect to direction of steam flow, and, preferably though not essentially a convergent dowstream portion 69.

The left-hand lane 64 is similar to the right-hand lane 65 and need not be further described.

In operation, steam exhausted from the turbine hood 46 ows downwardly through the condenser neck portion 43 into theV distribution region 60 with a high velocity steam core, indicated by the arrows 72, directed to the R.H. steam lane 65. As the high velocity steam core72 ows through the divergent lane portion 67, it undergoes rapid initial diiiusion with attendant substantial conversion of velocity to pressure. That is, the velocity head is reduced and the static pressure is correspondingly increased without substantial loss of energy.

The rate of divergence of the divergent portion 67 may be considerably greater than that of ordinary ditfusers without encountering boundary layer separation. This is feasible, since the spaces between the tubes 66 form suction passages connecting the steam lane with the air collection space 5S at the center of the tube field, which space 55 is maintained at reduced pressure by the air oiitake pipe 56. Accordingly, as the steam velocity is reduced during its flow through the divergent lane portion 67, it more readily turns to the left through the spaces between the tubes 66 to undergo heat exchange with the tubes and thus the turning losses due such ow are minimized. l u

At the same time as the steam is directed from the lane and condensed, and the incondensible gases, such as air are removed from the condenser by the oitake pipe 56, the mass ow of the remaining steam owing through the lower lane portion 69 is progressively diminished. Hence, the lower lane portion 69 may ybe made somewhat convergent without loss in flow efficiency, thereby permitting a greater number of tubes to be provided in the tube field and increasing the condensing capacity of the condenser without increasing the size of the condenser.

The L.H. lane 64 (FIG. 4) operates in the same manner as the R.H. lane 65, described above and is effective to diifuse the high velocity stea-m cores, indicated by arrows 74, exhausted from the turbine exhaust hood (not shown) disposed at the other end of the turbine 37 and corresponding to the exhaust hood 16 in FIG. l.

Referring to FIG. 2 again, there is shown a curve 31a, similar to the curve 31 described in conjunction with a prior arrangement, but showing the improved pressure distribution characteristics in the condenser neck portion 43 attained with the invention. The curve 31a has high total pressure end portions 32a and 33a and a low total pressure intermediate portion 34a, corresponding, respectively, to portions 32, 33 and 34 of the curve 31 but of correspondingly lower pressure value. Also, the static pressure value indicated by the dotted line 35a is lower than that indicated by the dotted line 35, previously described. The above phenomenon is attained primarily because of the substantial reduction in losses due to the eddies 28 and 29 (FIG. 1) and because of the highly eflicient and deffusion in the divergent portions of the steam lanes 63 and 64.

Since the total pressure levels indicated by the curve 31a are lower than those indicated by the curve 31, and since the static pressure level 35a is lower than that indicated by the dotted line 35, the turbine exhaust pressure (back pressure on the turbine) is commensurately lower, thereby permitting the steam to undergo greater useful expansion in the turbine before condensation in the condenser.

FIG. 5 illustrates another embodiment of the invention. In this embodiment, there is shown a dual condenser 75 comprising two identical tube fields 76 and 77 disposed in side-by-side relation within a common housing 78.

The condenser 75 serves to condense the exhaust of two tandem connected condensing turbines 79 and 80 of the double opposed-How type shown in FIG. 1.

The tube fields 76 and 77 are substantially similar in al1 aspects to the tube field 39 described in conjunction with FIGS. 3 and 4 and are disposed directly below their associated turbines 79 and 80.

The tubes in the periphery of the tube iield 77 together with the right-hand wall 81 of the housing form a steam lane 82, and, in a similar manner, the tube field 76 together with the left-hand wall 83 form a steam lane 84 similar to the steam lanes 64 and 65, respectively, previously described.

In this embodiment, however, the two tube fields 76 and 77 jointly define a -central steam lane 85. The central steam lane 85 is also provided with a divergent inlet portion 86, and a preferably slightly convergent downstream portion 87.

This embodiment operates in a manner similar to the first embodiment to reduce steam energy losses due to eddies, i.e., the high velocity steam cores 88 and 89 at the opposite ends of the turbines are-diffused in passage through the steam lanes 82 and S4, respectively. However, the high velocity steam cores 90 and 91 at the adjacent ends of the turbines are jointly directed to the central lane 85 and diffused in passage therethrough, in a manner similar to that previously described. The steam lane 85 is preferably of larger cross-sectional area than the lanes 82 and 84 to accommodate the greater mass fiow of steam.

It must further be pointed out that each tube field 77 and 76 is provided with a central air collection space 88 and 89, respectively. Accordingly, as the steam flows through the central lane 85, about 50% is turned into the left tube field 76 for condensation and the other 50% is turned into the right tube field for condensation. Hence, the boundary layer fluid is withdrawn past the tubes in both tube fields.

It will now be seen that the invention provides an arrangement wherein the high velocity cores of exhaust steam from a turbine of the double opposed-flow type are initially and rapidly diffused during flow through the steam lanes of a condenser with minimum loss of energy, thereby (l) reducing the back pressure on the turbine, (2) increasing the useful expansion availability of the steam through the turbine, and (3) increasing the heat exchange capacity of the condenser.

Although several embodiments of the invention have been shown, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications without departing from the spirit thereof.

I claim as my invention:

1. A surface condenser comprising a shell structure defining a chamber and having an inlet opening for admitting vapor to said chamber,

a tube field having a group of elongated tubes disposed in said chamber and in closely spaced relation with each other,

said tube field having a peripheral portion spaced from said shell structure and jointly therewith dening a vapor flow lane,

said vapor lane having an upstream end portion through which the vapor is directed and said peripheral portion being arranged in a manner to diffuse said vapor with attendant conversion of a portion of the velocity of said vapor into pressure,

means for directing a coolant fluid through said tubes, whereby in the resulting heat exchange the vapor is condensed, and

means associated with said chamber for collecting the condensate.

2. The structure recited in claim 1 wherein the peripheral portion of the tube field and the shell portion jointly impart a divergent shape to the upstream end portion of said vapor lane,

means is provided for withdrawing incondensible gases from the interior of the tube field, and

at least a portion of the boundary layer vapor flow in the divergent lane portion is directed towards the interior of the tube field.

3. The structure recited in lclaim 1 wherein the peripheral portion of the tube field and the shell portion jointly impart a shape to the vapor lane that is divergent in the direction of the vapor flow,

the tube field has a central portion devoid of tubes and defining a space,

means is prov-ided for imparting a reduced pressure in said space, and

at least a portion of the boundary layer vapor flow in the divergent lane portion is directed toward said space in a plurality of paths past the tubes.

4. In a turbine power plant, comprising a double ow vapor turbine having a rotational axis and a pair of exhaust outlets for expanded vapor axially spaced from each other; and

a surface condenser for condensing the expanded vapor from said pair of outlets,

said condenser comprising a shell structure defining a chamber having an inlet opening for admitting the vapor to said chamber,

a tube field having a group of elongated tubes disposed in closely spaced relation with each other in said chamber and extending substantially normal to said rotational axis,

said tube field having at least one peripheral portion spaced from said shell structure and jointly therewith defining a vapor fiow lane for the vapor flow from one of said exhaust outlets,

said vapor lane having an upstream end portion and a downstream portion extending from said end portion and diverging in downstream direction, whereby the ow of vapor through said vapor lane is initially diffused with attendant conversion of at least a portion of the velocity of said vapor into pressure,

means for directing a coolant fluid through said tubes, whereby in the resulting heat exchange the vapor is condensed,

means for evacuating incondensible gases from the interior of the tube field,

at least a portion of the boundary layer vapor flow in the divergent lane portion being withdrawn therefrom toward the interior of the tube field, and

means associated with the downstream portion of said chamber for collecting the condensate.

5. The structure recited in claim 4, wherein:

the peripheral portion of the tube field defining the vapor lane is provided with a plurality of spaces by the tubes and the boundary layer fiow is progressively directed through said spaces to promote the vapor diffusion.

6. In a turbine power plant comprising at least two double fiow vapor turbines connected in tandem and having a common rotational axis,

each of said turbines having a pair of axially spaced exhaust outlets for expanded vapor,

a surface condenser for condensing the expanded vapor from said outlets comprising a shell structure defining a chamber and means for admitting the vapor to said chamber,

a pair of tube fields in said chamber, each having a group of elongated tubes disposed in closely spaced relation with each other and extending normal to said rotational axis,

said tube fields being disposed in spaced side-by-side relation with each other and having juxtaposed peripheral portions jointly defining a central vapor ow lane having a divergent upstream inlet portion, whereby the flow of vapor through said vapor lane is initially diffused with attendant conversion of at least a portion of the velocity of said vapor into pressure,

means for directing a coolant uid through said tubes, whereby in the resulting heat exchange the vapor is condensed,

means for evacuating incondensible gases from the interior of said tube fields,

at least a portion of the boundary layer vapor flow in the divergent lane portion being withdrawn therefrom toward the interior of the tube fields, and

means disposed below said tube fields for collecting the condensate.

7. The structure recited in claim 6, wherein the peripheral portions of the tube tields defining the vapor lane are provided with a plurality of spaces by the tubes and the boundary layer flow in said diverging portion is progressively directed through said spaces to promote the vapor diffusion.

8. The structure recited in claim 6, wherein:

the divergent portion of the vapor lane comprises substantially less than 50% of the length of the vapor posed-flow vapor turbine of the condensing type havinga rotational axis and a pair of axially spaced exhaust outlets for expanded vapor,

said condensed comprising a shell structure disposed below said turbine and having an upper neck portion defining an inlet opening common to said pair of outlets and a pair of side Walls,

a tube field disposed in said chamber having a group of elongated tubes extending substantially normal to said rotational axis,

said tube field being of substantially symmetrical cross section about a vertical center line and having a pair of 'opposed outer peripheral portions disposed in spaced relation with the associated said side walls,

each of said peripheral tube field portions and associated side walls jointly defining a downwardly extending vapor lane having an inlet communicating with an asspciated turbine exhaust outlet and shaped in a manner to diffuse the incoming vapor with attendant conversion of at least a portion of the vapor velocity into vapor pressure,

means for directing a coolant uid through said tubes thereby to cool and' condense the vapor during flow therepast,

means communicating with the central portion of said tube iield for evacuating incondensible gases separated from the condensing vapor,

at least a portion of the boundary layer in the diffused vapor flow being withdrawn from said vapor lane in a progressive manner through the spaces between adjacent tubes toward said central portion, and means disposed in the lower portion of said shell for collecting the vapor condensate'. 10. A surface condenser comprising l a shell structure having an inlet opening for exhaust steam to be condensed, a tube field in said shell structure disposed below said inlet and substantially coextensive therewith, said tube field comprising a bundle of closely spaced tubes defining ow paths for the steam and having an internal portion devoid of tubes and forming an incondensible gas collection space, means for maintaining a reduced pressure in said space, the tubes in the periphery of said tube field at least partially deiining a pair of opposed steam flow lanes communicating with said steam inlet opening and au intermediate steam region between said lanes, said steam flow lanes receiving high velocity steam and being subject to a higher total pressure than said intermediate region, and the tubes in the periphery of said tube field defining said steam lanes being arranged in a manner to impart a divergent shape to said steam lanes thereby to substantially convert a portion of said total pressure to static pressure with minimum loss of energy.

References Cited UNITED STATES PATENTS 7/1924 Lonsdalev 165--114 5/1929 Kirgan 165-114

Claims

1. A SURFACE CONDENSER COMPRISING A SHELL STRUCTURE DEFINING A CHAMBER AND HAVING AN INLET OPENING FOR ADMITTING VAPOR TO SAID CHAMBER, A TUBE FIELD HAVING A GROUP OF ELONGATED TUBE DISPOSED IN SAID CHAMBER AND IN CLOSELY SPACED RELATION WITH EACH OTHER, SAID TUBE FIELD HAVING A PERIPHERAL PORTION SPACED FROM SAID SHELL STRUCTURE AND JOINTLY THEREWITH DEFINING A VAPOR FLOW LANE,