Air cooled vapor condenser module

Abstract

A module air cooled condenser with two generally vertical rows of horizontally extending heat exchanger tubes has an inlet tube sheet comprised of a structural member or a pair of structural members and a pair of outlet tube sheets to which are attached condensate headers. The module is appropriately enclosed on the top and frontal areas by sheet metal to provide an air plenum for the air flow which passes across the tube bundles from the fan mounted below the air plenum chamber. In another embodiment an additional row of tubes is provided whereby a reverse flow of vapor is maintained in order to decrease the occurrence of freeze up. In a further embodiment directed to freeze protection, all of the heat exchanger tubes slope downwardly toward the inlet tube sheet thereby having the condensate in contact with vapor at all times.

Claims

1. An air cooled heat exchange module comprising: a self-supporting inlet tube sheet, comprising at least one standard structural member, extending in a generally vertical direction and having a plurality of inlet holes therein forming two spaced apart generally vertical rows of said holes; a pair of tube bundles disposed in said holes supported by the inlet tube sheet and cantilevered outwardly from the inlet tube sheet; a pair of outlet tube sheets each supported by a tube bundle, accommodating the bundles and extending in a generally vertical direction; a pair of headers each supported by an outlet tube sheet communicating with the outlet tube sheets such that the condensate and non-condensed vapor are collected; means to close off the top and spaced between the outlet tube sheets of said module so that a plenum chamber is formed, and means to force air over the tube bundles. 2. A module according to claim 1 further comprising at least one row of reverse flow heat exchanger tubes extending between the outlet tube sheet and inlet tube sheet on the downstream side of each bundle with respect to the airflow. 3. A module according to claim 1 in which said tube bundles slope downwardly from said inlet tube sheet to said outlet tube sheets such that as condensate is formed, it gravitates toward said outlet tube sheets. 4. A module according to claim 1 in which said tube bundles slope downwardly from said outlet tube sheets to said inlet tube sheet such that as condensate is formed, it gravitates toward said inlet tube sheet where means are provided to collect the condensate. 5. A module according to claim 1 further comprising at least two tie rods which extend diagonally from the top of the inlet tube sheet to the bottom of an outlet tube sheet so that each tube bundle is partially supported by one of the tie rods. 6. A module according to claim 1 in which the inlet tube sheet is comprised of a pair of structural members joined together in a vapor tight manner and each having a generally vertical row of the inlet holes disposed therein. 7. A module according to claim 5 in which the structural member is a channel section. 8. A module according to claim 5 in which the structural member is an I-beam. 9. A module according to claim 5 in which the structural member is an H-beam. 10. A heat exchanger core for condensing vapor, comprising: a self-supporting structural element having a web, with a row of holes disposed therein, and flanges, thusly forming an inlet tube sheet; a tube bundle disposed in said holes supported by and cantilevered outwardly from said structural element; an outlet tube sheet supported by said tube bundle having a row of holes therein accommodating said bundle; and a header supported by said outlet tube sheet communicating with said outlet tube sheet so that the condensate and the non-condensed vapor are directed to the proper places. 11. A core according to claim 10 further comprising at least one row of reverse flow heat exchanger tubes extending between said outlet tube sheet and structural element on one side of said tube bundle. 12. A core according to claim 10 further comprising a tie rod which extends diagonally from the top of said structural element to the bottom of said outlet tube sheet so that said tube bundle is partially supported thereby.
United States Patent 1 1 Flitner et al. [451 Apr. 2, 1974 AIR COOLED VAPOR CONDENSER MODULE [73] Assignee: General Electric Company, Schenectady, NY. [22] Filed: Dec. 5, 1969 [21] Appl. N0.: 882,445 Primary Examiner- -Charles .l. Myhre Assistant Examiner-Theophil W. Streule, Jr. Attorney, Agent, or Firm-John F. Ahern; James W. Mitchell [57] ABSTRACT A module air cooled condenser with two generally vertical rows of horizontally extending heat exchanger tubes has an inlet tube sheet comprised of a structural member or a pair of structural members and a pair of outlet tube sheets to which are attached condensate headers. The module is appropriately enclosed on the top and frontal areas by sheet metal to provide an air plenum for the air flow which passes across the tube bundles from the fan mounted below the air plenum chamber. In another embodiment an additional row of tubes is provided whereby a reverse flow of vapor is maintained in order to decrease the occurrence of freeze up. In a further embodiment directed to freeze protection, all of the heat exchanger tubes slope downwardly toward the inlet tube sheet thereby having the condensate in contact with vapor at all times. 12 Claims, 7 Drawing Figures PAIENTEIJAPR 2 m4 3 8 00,861 7 sum 1 or 3 CONDENSATE CONDENSATE INVENTORSI DAVID P. FLITNER, PAUL e. LGHAYE, FRANZ J. NEUGEBAUER, THEIR ATTORNEY. mgm mra 21974 $800,861 SHEET 2 OF 3 INVENTORSI DAVID P. FLITNER, PAUL e. LoHAYE, FRANZ J. NEUGEBAUER, sY rif. THEIR ATTORNEY. MTENTED APR 2 I974 SFEH 3 SF 3 INVENTORS DAVID P. FLITNER, PAUL G. LGHAYE, FRANZ J. NEUGEBAUER, BY 1)! M1 l I I 1 I l I I f 1| ll IIIII I I l I I Ill 7 47 =:3 CONDENSATE CONDENSATE THEIR ATTORNEY. BACKGROUND OF THE INVENTION The present invention relates to heat exchangers which use air as the cooling medium. More particularly, it relates to a modular air condenser or cooler and an individual heat exchange core, which may be combined in groups to construct large vapor condensing plants. Air condensers have many applicables in industry including, for example, power generation with steam turbines, chemical manufacture, and oil refining. In such applications, it is desirable to reuse the condensed vapor over again in the particular cycle involved for a number of reasons. Another main consideration in the selection of air condensers is the scarcity of water or impurity of water for condensing purposes at a particular geographical location. Since air is readily available as a cooling medium, there is no need to locate the plant near a source of water, such as a river or the like. Using air also eliminates any pollution problems which often result when using natural water for industrial purposes. Air condensers or coolers can usually be of a more simple design when compared to a water condenser of the same capacity. However, certain problems are present in the prior art. One problem results from the fact that air has relatively poor heat transfer properties, thereby requiring large heat transfer surfaces when it is used as the cooling or heat receiving medium. Thus, such vapor condensers of large capacity are necessarily built with large dimensions. Of course, with large physical sizes, shipment becomes a problem and, in fact, has become a design criteria. With the present invention, a compact, high capacity and readily shippable air condenser module is provided. The individual heat exchange cores or tube bundles have become surfaces of great size, and attendant problems in construction and field erection have resulted. The present invention also desribes a heat exchanger/- core having a substantially horizontal, once-through parallel flow tube side circuit which utilizes as a tube sheet a structural element, thereby acting as structural support as well. The combination of such air condenser modules to form a large vapor condensing plant, thus eliminating the need for a separate vapor header, is the subject of a separate patent application Ser. No. 2,842 by the same assignee of the present invention and filed Jan. 14, 1970 now Pat. No. 3,677,338 granted July 18, 1972. Another problem commonly encountered with air condensers and well known to those skilled in the art is that of freeze up. As the vapor condenses, it may become subcooled and there by partially freeze in the heat exchanger core. Freeze protection requirements vary depending upon the severity of ambient conditions of wind and temperature, and even with mild conditions, it is very desirable to provide some means to substantially reduce freeze up. Accordingly, it is an object of the present invention to provide an air cooled condenser module which is both compact and of high condensing capacity. Another object is to utilize standard components in order to facilitate assembly and reduce cost. Yet another object is to provide a shippable module. A further object is to provide means to eliminate or substantially reduce freeze up in the heat exchanger tubes. Still a further object is to provide a module, easily erected, which may be employed as a component in a large vapor condensing plant. SUMMARY OF THE INVENTION Briefly stated, the invention is practiced in one form by providing an air condenser module with two tube bundles of substantially vertical rows of horizontally extending tubes diverging from a common inlet tube sheet to two spaced outlet tube sheets having condensate headers. The top of the module and the space between outlet tube sheets are covered by sheet metal to form an air plenum chamber. A fan at the bottom of the module provides the necessary cooling air flow. DRAWING The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to organization and method of practice, together with further objects and advantages thereof, may best be understood by reference to the following description. FIG. 1 is a front elevation view, partially cut away, of the present invention. FIG. 2 is a plan view, partially cut away, of the present invention. FIG. 3 is a sectional view taken along lines III-III of FIG. 1. FIG. 4 is a sectional view taken along lines IV--IV of FIG. 2. FIG. 5 is a side elevation view showing the reverse flow tubes of the alternate embodiment. FIG. 6 is a sectional view similar to FIG. 3 also showing the alternate embodiment. FIG. 7 is a side elevation view showing the downwardly sloping tubes. DESCRIPTION OF THE MODULE Referring now to FIGS. 1 and 2, the overall air condenser module is generally indicated at I. A module I is generally comprised ofa pair of heat exchanger cores or tube bundles 2 which extend horizontally from a common inlet tube sheet 3. Inlet tube sheet 3 may be comprised of a single structural element, thereby forming a double tube sheet, or it may be comprised of a pair of structural elements joined together as will be described in the subcombination core. Each tube bundle 2 generally consists of four rows of vertically aligned, horizontally extending tubes 4. The major portion of the weight of tube bundles 2 is supported by inlet tube sheet 3. Each of tubes 4 has fins 4a attached thereto which extend generally along their horizontal length in order to provide better heat exchange characteristics. Fins 4a may be of the continuous circular strip type or of the square plate type. Each tube 4 deviates slightly from the horizontal as it extends to an outlet tube sheet 5. The slight deviation may be on the order of 23 in order to facilitate the flow of condensate by gravity to the condensate header 6. This will be more fully described in the operation of the invention. It will be apparent from FIG. 1 that the rows of tubes 4 are slightly displaced from absolute vertical. As depicted, the deviation is on the order of 5, although it may be more or less, depending upon the desired characteristics of the air flow over the tube bundles 2. This angle is shown as a in FIG. 4. As previously mentioned, the horizontal tubes 4 extend to a pair of outlet tube sheets 5 to which are attached the generally vertically extending condensate headers 6. As the condensate is formed along the length of the tubes 4 during operation, it flows toward the condensate headers 6 from which it gravitates downward, flowing from the condensate header through drain hole 7, and thence to its point of use by condensate outlet line 8. This may be seen more clearly by reference to FIG. 3. The module 1 is enclosed by means provided by the top cover 11 and frontal cover 12 so as to form a plenum chamber indicated as 13. Positioned beneath the plenum chamber 13 and providing the air flow over tube bundles 2 is the fan 14. The air flows in the direction of the arrows as indicated on FIG. 1, that is, vertically upward into the plenum chamber 13, across the tube bundles 2, and on to the atmosphere. The air flow may be varied by several different methods, for example, providing a variable pitch fan, a variable speed fan, or adjustable louvers positioned between fan 14 and the bottom of tube bundles 2. The method of varying the air flow is not material to the present invention and is well known to those skilled in the art. A fan duct is provided in order to channel the air flow directly into plenum chamber 13. Fan duct 10 as well as the top cover 11 and frontal cover 12 may be comprised of sheet metal. The plenum chamber 13 is utilized with the enclosure means and slanted tube bundles in order to establish better and more uniform air flow across the tube bundles, thereby allowing more efficient condensation in the tubes. Providing structural support for the tube bundles 2 are tie rods 9 which extend diagonally from the bottom of outlet tube sheet 5 to the top of inlet tube sheet 3. It will be apparent that since horizontal tubes 4 extend through outlet tube sheet 5 and are partially supported thereby, that a diagonal tie rod 9 will support a large portion of the weight of a tube bundle 2. The tie rods 9 are of minimal thickness, just enough to support the necessary weight of tube bundle 2, so as not to interfere with the air flow. They are positioned on the downstream side of the tube bundles and are attached to the tube sheets in any suitable manner, such as welding. The joinder of tie rods 9 to the bottom of an outlet tube sheet 5 may be more clearly seen in FIG. 3. DESCRIPTION OF THE HEAT EXCHANGER CORE The individual heat exchanger core will now be described. The inlet tube sheet 3 of the module is comprised of a pair of suitable structural elements 15, each of which has a web portion 16 and flanges 17. It will be apparent that each core 2 has a separate tube sheet comprised of the structural element 15. These are standard structural elements produced by a suitable manufacturer and may be an H beam, I beam, or channel section. A structural element is employed as the tube sheet in order to provide support for the tube bundle as previously described and also to provide the support structure and wall member for the central vapor header of a large vapor condensing plant as is described in the aforementioned patent application. In the drawing of the module, two structural elements 15 comprising the inlet tube sheet 3 are joined together at a substantially vertical joint 18 in order to provide a vapor tight junction. As shown in FIG. 2, the two structural elements 15 are positioned at a small angle from one another and then joined together. This angle is not a critical part of the invention and is provided as an accommodation for the angle between the tube bundles which may vary between zero and approximately 30. The joinder together of the two structural elements forming tube sheet 3 is usually done prior to shipment and the entire air condenser module 1 is then shipped as a unit. However, the heat exchanger cores 2 could be shipped separately and then joined together at the field erection site. DESCRIPTION OF FREEZE PROTECTION MEANS Referring to FIGS. 5 and 6, an embodiment is shown which provides freeze protection for moderately severe ambient conditions. An additional row of heat exchanger tubes 19 are shown positioned on the downstream (with respect to the air flow) side of a standard tube bundle 2. The reverse flow tubes 19 extend between the same inlet tube sheet 3 and outlet tube sheet 5; however, as is apparent in the drawing, they deviate on the order of 5 in a direction downwardly from the outlet tube sheet 5 rather than the inlet tube sheet 3 as with tubes 4. Essentially, the inlet ends of tubes 19 are at the outlet tube sheet 5. At the outlet end of tubes 19 a manifold 20 is provided (partially shown in FIG. 5) which draws that portion of vapor not condensed in either of tubes 4 or reverse flow tubes 19 to the vapor jet air ejector (not shown). The condensate which forms in reverse flow tubes 19 gravitates downward through manifold 20 and joins with the condensate formed in tubes 4 at some appropriate point (not shown). It will be apparent to those skilled in the art that as the air flows over the rows of tubes 4, it is heated. As that vapor which has not been condensed is uniformly drawn into reverse flow tubes 19 by a pressure differential, the air which passes over tubes 19 is at a sufficiently high temperature to prevent subcooling upon the heat exchange between the vapor and flowing air. The vapor flow in the condensate header is indicated by the arrows in FIG. 6. Another embodiment designed to provide freeze protection is shown in FIG. 7 in which the heat exchanger tubes 4 slope downwardly toward the inlet tube sheet 3. By sloping the tubes 4 in such a manner, it will be appreciated that as the vapor is condensed in the tubes, the condensate will gravitate toward the inlet tube sheet where it will be collected by a hot well or other suitable means (not shown). Thus, in this embodiment, the need for a drain hole 7 and outlet line 8 may be eliminated. However, the condensate headers would now become vapor headers for collecting the uncondensed vapor and with a pressure difference provided, withdrawing the vapor from the header and tube area. OPERATION The vapor side of the inlet tube sheet 3 is in communication with other suitable elements forming a vapor header (not shown). As vapor flows through the vapor header, it enters the horizontal tubes flowing therethrough in a generally uniform manner from the bottom to the top of a heat exchange core. As the vapor is flowing through the tubes, air is passing over the heat exchanger cores in the direction as indicated by the arrows, thus providing a heat exchange relationship between the hot vapor and the cool flowing air. Throughout the tubes, as the vapor gives up its heat to the flowing air, it is condensed and the condensate then flows outward to the outlet tube sheet where it gravitates downward along the condensate header 6 and thence to its point of use. The operation of the embodiment with the reverse flow tubes has been previously described, as has the embodiment with all tubes being slanted downwardly toward the inlet tube sheet. It will be appreciated that an air condenser module with freeze protection and its associated heat exchanger cores have been described which may be built of large dimensions. For example, a heat exchanger core may have surface dimensions on the order of 12 by 20 feet or larger, depending on the vapor condensing capacity required. This is possible by using a standard structural element as the inlet tube sheet. A sufficiently large fan is required to provide the necessary air flow over the tube bundles. What we claim as new and desire to secure by Letters Patent of the United States is: 1. An air cooled heat exchange module comprising: a self-supporting inlet tube sheet, comprising at least one standard structural member, extending in a generally vertical direction and having a plurality of inlet holes therein forming two spaced apart generally vertical rows of said holes; a pair of tube bundles disposed in said holes supported by the inlet tube sheet and cantilevered outwardly from the inlet tube sheet; a pair of outlet tube sheets each supported by a tube bundle, accommodating the bundles and extending in a generally vertical direction; a pair of headers each supported by an outlet tube sheet communicating with the outlet tube sheets such that the condensate and non-condensed vapor are collected; means to close off the top and spaced between the outlet tube sheets of said module so that a plenum chamber is formed, and means to force air over the tube bundles. 2. A module according to claim 1 further comprising at least one row of reverse flow heat exchanger tubes extending between the outlet tube sheet and inlet tube sheet on the downstream side of each bundle with respect to the airflow. 3. A module according to claim 1 in which said tube bundles slope downwardly from said inlet tube sheet to said outlet tube sheets such that as condensate is formed, it gravitates toward said outlet tube sheets. 4. A module according to claim 1 in which said tube bundles slope downwardly from said outlet tube sheets to said inlet tube sheet such that as condensate is formed, it gravitates toward said inlet tube sheet where means are provided to collect the condensate. 5. A module according to claim 1 further comprising at least two tie rods which extend diagonally from the top of the inlet tube sheet to the bottom of an outlet tube sheet so that each tube bundle is partially supported by one of the tie rods. 6. A module according to claim 1 in which the inlet tube sheet is comprised of a pair of structural members joined together in a vapor tight manner and each having a generally vertical row of the inlet holes disposed therein. 7. A module according to claim 5 in which the structural member is a channel section. 8. A module according to claim 5 in which the structural member is an I-beam. 9. A module according to claim 5 in which thestructural member is an H-beam. 10. A heat exchanger core for condensing vapor, comprising: a self-supporting structural element having a web, with a row of holes disposed therein, and flanges, thusly forming an inlet tube sheet; a tube bundle disposed in said holes supported by and cantilevered outwardly from said structural element; an outlet tube sheet supported by said tube bundle having a row of holes therein accommodating said bundle; and a header supported by said outlet tube sheet communicating with said outlet tube sheet so that the condensate and the non-condensed vapor are directed to the proper places. 11. A core according to claim 10 further comprising at least one row of reverse flow heat exchanger tubes extending between said outlet tube sheet and structural element on one side of said tube bundle. 12. A core according to claim 10 further comprising a tie rod which extends diagonally from the top of said structural element to the bottom of said outlet tube sheet so that said tube bundle is partially supported thereby.

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