Air-cooled Condenser

Abstract

An air-cooled vapor-condensing plant having a plurality of individual air condenser modules joined together so that their inlet tube sheets together form a central vapor header, and also serve as primary structural members. Vapor enters the central vapor header, flows outwardly through heat exchange tubes where it is condensed by air flowing over the tubes.

Description

BACKGROUND OF THE INVENTION

The present invention relates to air-cooled condensers of very large capacity for use in conjunction with steam turbine powerplants, and more particularly, it relates to a modular construction for such condensers.

In large steam powerplants, the usual method of condensing the steam is by the use of water as a cooling medium. However, the scarcity of water in some areas or the problems of thermal pollution of rivers in other areas has led to suggestion for air-cooled condensers. Because of the poor heat transfer characteristics of air, such condensers are of massive size with large exposed surfaces of heat exchange tubing and having fans to circulate air over the tubes.

It has been suggested in the prior art that banks of tubes fed in parallel can be distributed or grouped with respect to a central distribution point with header pipes carrying the steam to the tubes. This construction is expensive and also gives rise to problems of uniform flow distribution of the vapor among the many tubes.

Also the arrangement of the cooling fans with respect to the tube banks or cores should be such as to best distribute cooling air with the minimum fan power and without the overall condenser proportions becoming excessively large.

Accordingly, one object of the present invention is to provide an improved modular construction for air-cooled condensers which simplifies the vapor header construction.

Another object of the invention is to provide an improved arrangement of the tube banks, vapor header and fans with respect to one another.

DRAWING

These and many other objects of the invention will become apparent by reference to the following description, taken in connection with the accompanying drawing, in which:

FIG. 1 is perspective view of a circular arrangement of the present invention.

FIG. 2 is a sectional view taken along lines II--II of FIG. 1 and shows a plan view of the bottom inside structure with one module shown.

FIG. 3 is a sectional view taken along lines III--III of FIG. 2 and shows an inside elevation of the bottom structure of the vapor condensing plant.

FIG. 4 is a perspective along the lines of FIG. 1 showing an alternate embodiment having a top mounted fan. FIG. 5 is a plan view of another alternate embodiment which may utilize the present invention.

SUMMARY OF THE INVENTION

Briefly stated, this invention is practiced in one embodiment by joining together a plurality of air condenser modules such that the inlet tube sheets of the several modules form the central vapor header. In the primary embodiment, each module has an individual fan mounted thereunder, such that a variety of planned configurations may be designed using the inlet tube sheet of such module as part of the vapor header.

DESCRIPTION OF THE INVENTION

Referring now to FIG. 1, the overall vapor-condensing plant is generally indicated as 1. It is to be noted that, although FIG. 1 depicts the vapor-condensing plant 1 as a circular design, the individual condenser modules 2 may be joined together in other configurations as will be described in a description of one alternate embodiment. Vapor-condensing plant 1 is comprised of circumferentially spaced individual condenser modules 2. Although these separate condenser modules are the subject of a separate patent application filed of even date herewith and assigned to the assignee of the present invention, a brief description of the individual modules 2 will be made in order to better understand the inventive concept of the present invention.

Each condenser module 2 is an individual unit which may be assembled in the factory and then shipped to the power plant site where the modules 2 are joined together. Each module 2 is comprised of a pair of heat exchange cores 3. A better understanding of the module 2 may be had by referring also to FIG. 2 wherein a plan view of an individual module 2 is shown. The cores 3 are generally flat surfaces of large dimensions comprised of a plurality of generally horizontally extending heat exchange tubes 4. In most applications, the tubes 4 would be of the finned type. The heat exchange tubes 4 extend outwardly to an outlet tube sheet indicated as 5. As the vapor to be condensed passes along the heat exchange tubes 4, the condensate that is formed will flow outwardly and then gravitate downward through a condensate header 6. Each core 3 has a condensate header 6 so as to collect the condensate and direct it to a common collection ring 24, as will be more fully described in a subsequent part of this description. Forming a closure means on the top of each module 2 is top plate 27 which extends between the two cores 3 and radially outward to the ends of heat exchange tubes 4 and top of outlet tube sheet 5. The closure means along the front area of modules 2 is front plate 8 which extends in a generally vertical direction from the bottom of the cores 3 to the top of the cores where it is attached to top plate 7 thus closing off the condenser modules 2 in order to from a plenum chamber 9. The inner wall of plenum chamber 9 is formed by the inlet tube sheet generally indicated as 10, which may be seen clearly in FIG. 2. The inlet tube sheet 10, in the preferred embodiment is formed by a pair of structural elements generally indicated as 11. The structural element 11 may be an H-beam, I-beam, or a channel section depending upon the design requirements. Structural elements 11 have flange portions 12 and web portions 13, thus providing the structural rigidity for constructing the large vapor condensing plant 1. The two structural elements 11 comprising the inlet tube sheet 10 are joined together along a vertical joint 14 which is made vaportight. The method of joining may be by any suitable manner such as welding. It will be apparent that inlet tube sheet 10 can be constructed from a single structural element rather than joining together two individual structural elements.

Mounted beneath each condenser module 2 on a mounting structure 15 is a fan 16. A transition piece or skirt 17 surrounds the fan 16 and extends upwardly to the bottom of module 2 and serves to direct the airflow provided by the fan up into the air plenum chamber 9. The arrows shown on FIG. 1 indicate the direction of the air flow through each module 2, which is up into plenum chamber 9, transversely through the cores, and then continuing up parallel to the cores. This basic flow pattern is used in all of the configuration to be described.

The overall vapor-condensing plant 1 will now be described in detail. A central vapor header 18 is formed by the joining together at a vertical joint 19 the inlet tube sheets 10. It will be appreciated that because the inlet tube sheet 10 are structurally rigid they are able to form the central vapor header 18 which supports the entire structure, thus the excess steam piping which was necessary in the prior art is eliminated as well as much of the heavy support structure. A covering plate 20 extends over the top of the central vapor header 18 providing a closed structure for the containing of vapor therein.

Referring now to FIG. 3, as well as FIGS. 1 and 2, a bottom covering plate 21 extends across the bottom of the central steam header 18, thus completing the enclosure of the central vapor header 18. In the central portion of cover plate 21 is vapor inlet hole 22. Extending through vapor inlet hole 22 is vapor inlet duct 23. Duct 23 is connected to the covering plate 21 in a vaportight manner. The opposite end of vapor inlet ducting 23 leads to the source of vapor to be condensed (not shown). Extending circumferentially around the bottom of the modules 2 and communicating with the condensate headers 6 is the condensate collector ring 24. It is into condensate collector ring 24 that the condensate flows as it gravitates downward through condensate header 6. Collector ring 24 is shown as a circumferential ring although it may take any suitable shape. At a suitable point along collector ring 24, a condensate line 25 is attached which leads to the central vapor header 18. Condensate line 25 directs the collected condensate to the hot well area 26 within central vapor header 18 which is formed by the inlet tube sheets 10, inlet duct 23, and bottom plate 21. It will be understood that the collected condensate may be directed to its point of use without first going to the hot well area 26, but by directing the condensate first through the hot well, the incoming vapor can be precooled before entering the tubes. A condensate outlet line 27 extends from and through bottom covering plate 21 to the point of use of the condensate such as the boiler feed pump (not shown).

The vapor-condensing plant 1 is supported at the installation site by a mounting structure generally indicated at 28. Although a specific mounting structure will now be described, it should be pointed out that other suitable means may be utilized such that the condensing plant 1 is sufficiently supported.

Referring to FIGS. 1 and 3, it may be seen that every other structural element 11 extends downwardly beyond the bottom of the hot well area 26 such that an open space is formed between the bottom of the hot well area and the ground. The extensions 29 of the structural elements 11 are fastened to a suitable base bay means of bolting 30 or the like. Thus, the inlet tube sheet members support the entire central portion of the condenser plant 1.

ALTERNATE EMBODIMENTS

In the alternate embodiment shown in FIG. 4, the arrangement of the individual condenser modules 2 is generally the same and like elements are indicated by like numbers. The primary difference between the two embodiments is that with a ground mounted fan 16 (FIG. 1), the air is forced up and through the modules 2, whereas in the alternate embodiment (FIG. 4), a single top mounted fan 31 is employed to pull the air up through the individual modules 2. The fan 31 may be mounted atop the covering plate 20 and is generally surrounded by the upwardly extending top transition piece or skirt 32. The skirt 32 serves to direct the pulled air directly out of the vapor condensing plant 1. In order to employ a single fan, the top plate 7 is positioned across the tops of adjacent condenser modules 2, thus leaving the top of each module open. All other elements in this embodiment are as described in the previous embodiment. The flow of air is similar to that in FIG. 1, out upwardly into the space between modules 2, transversely through the cores 3, and then continuing upwardly through the module and out the top of the plant.

Another embodiment of the vapor condenser plant 1 is shown in FIG. 5, where the modules 2 are arranged in a linear array rather than in circular fashion. In this embodiment, the individual condenser modules 2 are positioned such that the structural inlet tube sheets 10, in cooperation with transition walls 33, form an "in line" central vapor header generally indicated as 34. The condensate collector ring of the first described embodiment will also be in a generally "in line" relationship to the steam header 34 and is indicated as 35. Only six condenser modules 2 are shown in FIG. 5, but any number may be added to form a longer "in line" central vapor header 34, thereby increasing the capacity of the overall vapor condensing plant 1. Other designs, when compensating for space limitations and and the like, are also possible. When utilizing the "in line" plan, it will be appreciated that ground mounted fans must be employed for each individual module. The airflow is upward, transversely through the cores and then continues upward and out of the plant as before.

OPERATION OF THE INVENTION

The operation of the first embodiment will now be described. As vapor enters the central vapor header 18 and generally occupies the space therein, it begins to flow outwardly through the heat exchange tubes 4 comprising the cores 3. As the vapor is flowing outwardly through the tubes, the ground mounted fans are forcing air up into the plenum chambers 9 and transversely across the cores 3. The air cools the hot vapor within tubes 4, thereby condensing a part or all of the vapor. As the condensate is formed, it flow radially outward and then gravitates downward through the condensate headers 6 to the condensate collector ring 24. From this point, the condensate may be directed to its point of use or it may be directed into the hot well area of the central vapor header 18, where it precools the hot vapor that is entering the central vapor header. This generally provides slightly better condensing characteristics. From the hot well, the condensate is then directed to its point of use.

In the alternate embodiment of FIG. 4, the flow of vapor and condensate is generally the same but due to the top mounted fan 31, the airflow is reversed over the cores 3.

In the still further embodiment of FIG. 5, showing the "in line" central vapor header, the airflow through the individual condenser modules 2 is substantially the same as that in FIG. 1. The vapor flow is generally linear along the "in line" vapor header 34 from where it flows outwardly through the heat exchange tubes 4 in each condenser module 2. As the vapor flows outwardly through the cores, it is condensed and is collected at the collector line after it gravitates downward.

It will be apparent from the foregoing description that a large vapor-condensing plant has been described which may take on various plan forms owing to the flexibility of the individual condenser modules which utilize a structural element or elements as the inlet tube sheets. Since a central vapor header is formed by the inlet tube sheets, the necessity of such a separate element is eliminated, thereby further reducing space requirements and cost.

While there is shown what is considered at present to be the preferred embodiment of the invention, it is of course understood that various other modifications may be made therein, and it is intended to cover in the appended claims all such modifications as fall within the true spirit and scope of the invention.

Claims

What is claimed as new and desired to secure by Letters Patent of the United States is:

1. A modular air-cooled vapor condensing plant, comprising:

a plurality of spaced condenser modules, each having a generally vertical inlet tube sheet comprised of at least one structural member which provides a major structural support for each said condenser module and said condensing plant,

heat exchanger tubes extending outwardly from each inlet tube sheet to a generally vertical outlet tube sheet,

a central vapor header defined in part by said inlet tube sheets when selected ones of inlet tube sheets are connected together along a generally vertical joint,

closure means for the top and bottom of said vapor header,

at least one vapor inlet line to supply said vapor header, means to collect the condensate as it flows from the heat exchanger tubes, fan means to force air vertically in a direction generally parallel to said modules, and means blocking off the space between alternate modules, whereby air is forced transversely across the heat exchanger tubes to condense the vapor passing from the central vapor header.

2. A condensing plant according to claim 1 in which said inlet tube sheets are comprised of structural members having flange portions to provide stiffness.

3. 3. A condensing plant according to claim 1 in which said inlet tube sheets together extend downwardly substantially beyond said heat exchanger tubes to provide major structural support for said condensing plant.

4. A condensing plant according to claim 1 in which said vapor inlet line enters said vapor header through the bottom closure means and extends upwardly therein, thusly defining a hot well area towards the bottom of said vapor header.

5. A condensing plant according to claim 1 in which said collecting means is comprised of a condensate header positioned on the outside of each said outlet tube sheet, each condensate header being connected to a collection ring surrounding said condensing plant into which the condensate flows from where it is directed to its point of use.

6. A condensing plant according to claim 5 in which said collecting means further includes a condensate line from said collection ring to the hot well area.

7. A condensing plant according to claim 1 in which said fan means is a single fan mounted atop said plant and wherein said blocking means includes plates between modules at the top thereof and plates closing off said modules at the bottom thereof, such that air is pulled up, across said heat exchange tubes, and on up through said modules.

8. A condensing plant according to claim 1 in which said fan means is a plurality of fans, and wherein said blocking means includes a plate across the top of said module, whereby air is pushed upward and transversely across the heat exchange tubes.