Abstract:
The present invention relates to a mechanical draft cooling tower that employs air cooled condenser modules. The aforementioned cooling tower operates by mechanical draft and achieves the exchange of heat between two fluids such as atmospheric air, ordinarily, and another fluid which is usually steam. The aforementioned cooling tower utilizes a modular air cooled condenser concept wherein the air cooled condensers utilize heat exchange deltas that use tube bundles that are manufactured and assembled prior to being shipped to the tower site.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a mechanical draft cooling tower that utilizes air cooled condenser modules. The aforementioned cooling tower operates by mechanical draft and achieves the exchange of heat between two fluids such as atmospheric air, ordinarily, and another fluid which is usually steam or some sort of industrial process fluid. The aforementioned cooling tower operates by mechanical draft which utilizes an air current generator such as a fan or the like. 
       BACKGROUND OF THE INVENTION 
       [0002]    Cooling towers are heat exchangers of a type widely used to emanate low grade heat to the atmosphere and are typically utilized in electricity generation, air conditioning installations and the like. In a mechanical draft cooling tower for the aforementioned applications, airflow is induced or forced via an air flow generator such as a driven impeller, driven fan or the like. Cooling towers may be wet or dry. Dry cooling towers can be either “direct dry,” in which steam is directly condensed by air passing over a heat exchange medium containing the steam or an “indirect dry” type cooling towers, in which the steam first passes through a surface condenser cooled by a fluid and this warmed fluid is sent to a cooling tower heat exchanger where the fluid remains isolated from the air, similar to an automobile radiator. Dry cooling has the advantage of no evaporative water losses. Both types of dry cooling towers dissipate heat by conduction and convection and both types are presently in use. Wet cooling towers provide direct air contact to a fluid being cooled. Wet cooling towers benefit from the latent heat of vaporization which provides for very efficient heat transfer but at the expense of evaporating a small percentage of the circulating fluid. 
         [0003]    To accomplish the required direct dry cooling the condenser typically requires a large surface area to dissipate the thermal energy in the gas or steam and oftentimes may present several challenges to the design engineer. It sometimes can be difficult to efficiently and effectively direct the steam to all the inner surface areas of the condenser because of non-uniformity in the delivery of the steam due to system ducting pressure losses and velocity distribution. Therefore, uniform steam distribution is desirable in air cooled condensers and is critical for optimum performance. Another challenge or drawback is, while it is desirable to provide a large surface area, steam side pressure drop may be generated thus increasing turbine back pressure and consequently reducing efficiency of the power plant. Therefore it is desirous to have a condenser with a strategic layout of ducting and condenser surfaces that allows for an even distribution of steam throughout the condenser, that reduces back pressure, while permitting a maximum of cooling airflow throughout and across the condenser surfaces. 
         [0004]    Another drawback to the current air cooled condenser towers is that they are typically very labor intensive in their assembly at the job site. The assembly of such towers oftentimes requires a dedicated labor force, investing a large amount of hours. Accordingly, such assembly is labor intensive requiring a large amount of time and therefore can be costly. Accordingly, it is desirable and more efficient to assemble as much of the tower structure at the manufacturing plant or facility, prior to shipping it to the installation site. 
         [0005]    It is well known in the art that improving cooling tower performance (i.e. the ability to extract an increased quantity of waste heat in a given surface) can lead to improved overall efficiency of a steam plant&#39;s conversion of heat to electric power and/or to increases in power output in particular conditions. Moreover, cost-effective methods of manufacture and assembly also improve the overall efficiency of cooling towers in terms of cost-effectiveness of manufacture and operation. Accordingly, it is desirable for cooling tower that are efficient in both in the heat exchange properties and assembly. The present invention addresses this desire. 
         [0006]    Therefore it would desirous to have an economical, mechanical draft, modular cooling tower that is efficient not only in its heat exchange properties but also in its time required for assembly and cost for doing the same. 
       SUMMARY OF THE INVENTION 
       [0007]    Embodiments of the present invention advantageously provides for a fluid, usually steam and method for a modular mechanical draft cooling tower for condensing said steam. 
         [0008]    An embodiment of the invention includes a method for assembling a modular air cooled condenser extending along a vertical axis away from horizontal, comprising the steps of: assembling a first condenser bundle assembly having a first set of tubes having first and second ends, a steam manifold connected to the first ends of the tubes, and a condensate header connected to the second ends of the tubes; assembling a second condenser bundle having a second set of tubes having first and second ends, a steam manifold connected to the first ends of the tubes, and a condensate header connected to the second ends of the tubes; placing the first and second condenser bundle assemblies in to a container; transporting the container to a location upon which the modular air cooled condenser will be assembled; assembling a heat exchange delta by placing the first condenser bundle and the second condenser bundle; and positioning the heat exchange delta on a modular tower frame. 
         [0009]    Another embodiment of the present invention includes a modular air cooled condenser extending along a vertical axis away from horizontal, comprising: means for assembling a first condenser bundle assembly having a first set of tubes having first and second ends, a steam manifold connected to the first ends of the tubes, and a condensate header connected to the second ends of the tubes; means for assembling a second condenser bundle assembly having a second set of tubes having first and second ends, a steam manifold connected to the first end of the tubes, and a condensate header connected to the second ends of the tubes; means for placing the first and second condenser bundle assemblies in to a container; means for transporting the container to a location upon which the modular air cooled condenser will be assembled; means for assembling a heat exchange delta by placing using the first condenser bundle and the second condenser bundle; and means for positioning the heat exchange delta on a modular tower frame. 
         [0010]    Another embodiment of the present invention, A mechanical draft modular air cooled condenser that cools an industrial fluid is disclosed, comprising: a plenum with which at least one delta resides wherein said at least one delta comprises first condenser bundle having a first set of tubes having first and second ends, a steam manifold connected to the first ends of the tubes, and a condensate header connected to the second ends of the tubes; and a second condenser bundle having a second set of tubes having first and second ends, a steam manifold connected to the first ends of the tubes, and a condensate header connected to the second ends of the tubes; a support frame that supports said plenum; and a shroud that houses an air current generator. 
         [0011]    In yet another embodiment of the present invention, a method for assembling a modular air cooled condenser extending along a vertical axis is disclosed, comprising: assembling a first condenser bundle having a first set of tubes having first and second ends and a condensate header connected to the second end of the tubes; assembling a second condenser bundle having a second set of tubes having first and second ends, and a condensate header connected to the second end of the tubes; placing the first and second condenser bundles in to a container; transporting the container to a location upon which the modular air cooled condenser will be assembled; assembling a heat exchange delta by placing using the first condenser bundle and the second condenser bundle; and positioning the heat exchange delta on a modular tower frame. 
         [0012]    There has thus been outlined, rather broadly, certain embodiments of the invention in order that the detailed description thereof herein may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional embodiments of the invention that will be described below and which will form the subject matter of the claims appended hereto. 
         [0013]    In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of embodiments in addition to those described and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting. 
         [0014]    As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The above-mentioned and other features and advantages of this disclosure, and the manner of attaining them, will become more apparent and the disclosure itself will be better understood by reference to the following description of various embodiments of the disclosure taken in conjunction with the accompanying figures. 
           [0016]      FIG. 1  is a perspective view of an air cooled condenser module in accordance with an embodiment of the present invention. 
           [0017]      FIG. 2  is a schematic side view of the air cooled condenser module depicted in  FIG. 1  in accordance with an embodiment of the present invention. 
           [0018]      FIG. 3  is another schematic side view of the air cooled condenser module depicted in  FIG. 1  in accordance with an embodiment of the present invention. 
           [0019]      FIG. 4  is a perspective view of an A-type condenser configuration in accordance with an embodiment of the present invention. 
           [0020]      FIG. 5  illustrates the condenser bundles in a packaged arrangement for shipping in accordance with an embodiment of the present invention. 
           [0021]      FIG. 6  schematically illustrates the steps of assembly of an air cooled condenser in accordance with an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0022]    In the following detailed description, reference is made to the accompanying drawings, which form a part hereof and show by way of illustration specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice them, and it is to be understood that other embodiments may be utilized, and that structural, logical, processing, and electrical changes may be made. It should be appreciated that any list of materials or arrangements of elements is for example purposes only and is by no means intended to be exhaustive. The progression of processing steps described is an example; however, the sequence of steps is not limited to that set forth herein and may be changed as is known in the art, with the exception of steps necessarily occurring in a certain order. 
         [0023]    Turning now to  FIG. 1 , a modular air cooled condenser module, generally designated  10 , is illustrated. The air cooled condenser module  10  generally includes a plenum  12 , having an air current generator or fan disposed within a fan shroud or inlet bell  14  and a plurality of support columns or legs  16 . The air cooled condenser module  10  further includes multiple A-type geometry deltas, each designated  18 . Each delta  18  comprises two tube bundle assemblies  28  with a series of finned tubes to conduct heat transfer. The deltas  18  will be discussed in further detail below. 
         [0024]    Turning now to  FIGS. 2 and 3 , schematic side views of the air cooled condenser  10  are depicted. As specifically illustrated in  FIG. 2 , the air cooled condenser employs risers  20  which are welded to the main steam duct  22 . The risers  20  are connected to a steam manifold  24  which operates to keep the steam flow velocity more constant. This above described configuration is part the A-type condenser bundles  28  that are shipped as a unit from the factory, which will be discussed in further detail below. The condenser bundles  28  are preferably welded to the risers  20  via a transition piece  26  to accommodate the geometry of the steam manifold. 
         [0025]    Turning now to  FIG. 4 , a delta  18  is illustrated. As depicted, each delta  18  is comprised of two individual heat exchange bundle assemblies  28 , each having a series of finned tubes. The individual tubes are approximately two (2) meters in length whereas the bundle length is approximately twelve (12) meters. As illustrated, each bundle assembly  28  is positioned at an angle to one another to form the A-type configuration of the delta  18 . While the bundle assemblies  28  may be positioned at any desired angle, they preferably are positioned at an angle approximately twenty degrees (20°) to approximately thirty degrees (30°) from vertical and approximately sixty degrees (60°) to approximately seventy degrees (70°) from horizontal. More specifically, the bundle assemblies  28  are positioned at twenty-six degrees (26°) from vertical and sixty-four degrees (64°) from horizontal. 
         [0026]    Each of the bundle assemblies  28  are assembled prior to shipping wherein each comprises a riser to header transition piece  26 , steam manifold  24 , finned tubes  25 , and steam condensate headers  27 . As can be seen in  FIG. 1 , due to the modular design and orientation of the bundle assemblies  28 , the air cooled condenser design  10  has approximately five (5) times more tubes as compared to typical designs. Moreover, the embodiments of the current invention not only utilize five (5) times the tubes, but employ condenser tubes that are much shorter in length. As result of the aforementioned design and orientation, the steam velocity traveling through the tube bundles  28  is reduced as result of the increased number of tubes in combination with the reduced tube length, and therefore steam pressure drop within the deltas  18  is reduced, making the air cool condenser  10  more efficient. 
         [0027]    Typically, turbine back pressure of an air cooled condenser or the like is limited by the maximum steam velocity in the tubes (to limit erosion) wherein the steam velocity is increasing with a decrease of back pressure (due to density of steam). Thus, due to the addition of tubes in accordance with the present invention, the steam is still maintained at the maximum allowable steam velocity but at a lower back pressure. The other limitation the current delta design addresses is that the pressure at the exit of the secondary bundles cannot be less than the vacuum group capability. This pressure typically results from turbine back pressure minus the pressure drop in ducting minus the pressure drop in the tubes. Accordingly, due to the reduced pressure drop in the tubes, the allowable turbine back pressure is lower with the delta  18  design. 
         [0028]    Furthermore, the above-described bundle design also reduces the pressure drop within the individual delta  18 . For example, the heat exchange that takes place via the deltas  18 , is dependent upon the heat exchange coefficient, i.e., the mean temperature difference between air and steam and the exchange surface. Due to the reduced pressure drop as previously described, the mean pressure (average between inlet pressure and exit pressure) in the exchanger is higher with the design of the current condenser configuration  10 . In other words, because steam is saturated, the mean steam temperature is also higher for the same heat exchange surface resulting in increased heat exchange. 
         [0029]    Turning now to  FIG. 5 , a transport container, generally designated  30  is illustrated. As the name suggests, the transport container  30  is used to transport the bundles  28 , from the factory to the job site. As illustrated, the condenser bundles  28 , are manufactured and assembled at the factory with the respective steam manifold  24  and steam condensate headers  27 . While five (5) bundles are illustrated positioned in the transport container, more or less individual bundles may be shipped per container depending as needed or required. 
         [0030]    Alternatively, the above described embodiments of the present employ tube bundles manufactured and assembled, prior to shipping, having steam manifold  24  and steam condensate headers  27 , alternative embodiment bundles may not include a manifold prior to shipping. More specifically, in such embodiments, the tube bundles may be ship without steam manifolds  24  attached thereto. In said embodiments, the tube bundles  28  may be assembled in field to form the A-type configuration, as discussed above. However, instead of employing two steam manifolds, this alternative embodiment may employ a single steam manifold wherein the single steam manifold extends along the “apex” of the A configuration. 
         [0031]    Referring now to  FIG. 6 , a flow chart is illustrated, schematically depicting the steps of assembly of the air cooled condenser tower  10 . As previously described, the individual tube bundles  28  are assembled prior to shipment to the job site, as referenced by numeral  40 . Each individual bundle assembly  28  includes a plurality of finned tubes  25  along with a steam manifold  24  and steam condensate header  27 . As previously discussed in connection with the previous figures of the specification, the bundle assemblies  28  are pre-manufactured at the factory prior to placing the individual bundle assemblies  28  in the shipping container  30  as identified by numeral  42 . The shipping containers  30  are then shipped to the erection field site. 
         [0032]    Next, the delta, generally indicated as  18 , is assembled in the field as identified by numerals  44  and  46 . As previously described, while the bundles may be positioned at any desired angle, they preferably are positioned at an angle (y) approximately twenty degrees (20°) to approximately thirty degrees (30°) from vertical and an angle (x) approximately sixty degrees (60°) to approximately seventy degrees (70°) from horizontal. More specifically, the bundles are positioned at twenty-six degrees (26°) from vertical and sixty-four degrees (64°) from horizontal. As designated by numeral  46 , a single A-type delta is illustrated  18  formed by two bundle assemblies  28  to form the “A” configuration. The bundle assemblies  28  self support one another in this configuration. 
         [0033]    Turning now to the air cooled condenser module  10  as referenced by the numeral  48 , it is depicted employing five deltas  18 . As discussed above, the air cooled condenser is an improvement over current air cooled condenser types and it has a high “pre-fabrication” level which equates to reduced installation cost and reduced installation time. Moreover, the above-described design reduces the pressure drop, thereby providing a more efficient heat exchange apparatus. 
         [0034]    The many features and advantages of the invention are apparent from the detailed specification, and, thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, for example a forced draft air cooled condenser has been illustrated but an induced draft design can be adapted to gain the same benefits and, accordingly, all suitable modifications and equivalents may be resorted to that fall within the scope of the invention.