Abstract:
A coalescer includes a frame with at least one crossmember for securing a flexible coalescing net assembly. The coalescing net assembly is disposed across openings in the frame for capturing moisture in air flowing through the coalescer. The coalescing net assembly has an area greater than the frame area for increasing coalescing efficiency.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The subject matter disclosed herein relates to gas turbine air filtration, in particular, to coalescers that remove free form moisture, or droplets, from intake air used by the gas turbine. 
         [0002]    Generally, gas turbine filtration enclosures and systems that are situated in relatively dry, desert regions are challenged by a combination of relatively high dust, particulate and contaminant loads along with local environmental conditions that can include heavy fog periods. The combination of these can prove challenging for final, high efficiency filters even with pulse cleaning systems installed. This is because the combination of conditions can create a mud-like cake on the filters that shortens their operational life. 
         [0003]    The traditional and existing approach to solving this issue is to use coalescers and air filters upstream of the final high efficiency filters as a low cost, cleanable protection system for the more expensive final filters. The coalescers may, however, require intensive maintenance with frequent change out periods due to the high pressure drops created by clogged coalescers. One factor that contributes to the clogging of coalescers used in the first stage of air filtration systems is that the coalescers capture both dirt and moisture which accelerates clogging. Another factor is that the surface area presented by the coalescers to the intake air is inadequate to efficiently remove moisture from the volume of air passing through the coalescers. Accordingly, there is a need for coalescers having increased surface area that efficiently remove moisture from intake air without causing excessive pressure drops. 
         [0004]    The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0005]    A coalescer includes a frame with at least one crossmember for securing a flexible coalescing net assembly. The coalescing net assembly is disposed across openings in the frame for capturing moisture in air flowing through the coalescer. An advantage that may be realized in the practice of some disclosed embodiments of the coalescers disclosed herein is improved coalescing efficiency due to a greater coalescing surface area without generating excessive pressure loss. 
         [0006]    In one embodiment, a coalescer includes a frame with side, top, and bottom frame members connected together. A crossmember attached to the top and bottom frame members forms frame openings. A coalescing net assembly is disposed across the frame openings to capture moisture in air flowing through the coalescer. The coalescing net assembly has an area greater than the frame area, is attached to the side frame members, and is in contact with the crossmember. 
         [0007]    In another embodiment, a coalescer includes a frame with side, top, and bottom frame members. A pair of exterior crossmembers and a number of interior crossmembers are attached to the top and bottom frame members to form frame openings. A coalescing net assembly is disposed across the frame openings to capture moisture in air flowing through the coalescer. The coalescing net assembly has an area greater than the area of the frame, is attached to the pair of exterior crossmembers, and is in contact with the interior crossmembers. 
         [0008]    This brief description of the invention is intended only to provide a brief overview of subject matter disclosed herein according to one or more illustrative embodiments, and does not serve as a guide to interpreting the claims or to define or limit the scope of the invention, which is defined only by the appended claims. This brief description is provided to introduce an illustrative selection of concepts in a simplified form that are further described below in the detailed description. This brief description is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all disadvantages noted in the background. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    So that the manner in which the features of the invention can be understood, a detailed description of the invention may be had by reference to certain embodiments, some of which are illustrated in the accompanying drawings. It is to be noted, however, that the drawings illustrate only certain embodiments of this invention and are therefore not to be considered limiting of its scope, for the scope of the invention encompasses other equally effective embodiments. The drawings are not necessarily to scale, emphasis generally being placed upon illustrating the features of certain embodiments of the invention. In the drawings, like numerals are used to indicate like parts throughout the various views. Thus, for further understanding of the invention, reference can be made to the following detailed description, read in connection with the drawings in which: 
           [0010]      FIG. 1  is a top cross-sectional diagram of an exemplary coalescer; 
           [0011]      FIG. 2  is a side view of the exemplary coalescer of  FIG. 1 ; 
           [0012]      FIG. 3  is a front view of the exemplary coalescer of  FIG. 1 ; 
           [0013]      FIG. 4  is a top cross-sectional diagram of another exemplary coalescer; 
           [0014]      FIG. 5  is a side view of the exemplary coalescer of  FIG. 4 ; and 
           [0015]      FIG. 6  is a front view of the exemplary coalescer of  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0016]    With reference to  FIGS. 1-3 , a coalescer  100  is provided as an upstream air treatment assembly in a gas turbine or other industrial application requiring moisture filtration. The coalescer  100  includes a frame  105  having parallel top and bottom frame members  121 ,  122  attached to parallel side frame members  123 ,  124 . The frame  105  surrounds a frame intake area  116  generally defined by a frame width  117  and a frame height  118 . A central frame member, or crossmember,  125  is attached to the top and bottom frame members  121 ,  122  between the side frame members  123 ,  124  to divide the frame intake area  116  into two frame openings  119 ,  120 . Coalescing nets  101 ,  102 ,  103 ,  104  are attached to the top and bottom frame members  121 ,  122 , the side frame members  123 ,  124 , and to the crossmember  125 . The top and bottom frame members  121 ,  122  are attached to the side frame members  123 ,  124  at their ends to form a substantially rigid or semi-rigid frame  105  made from, for example, a plastic or metal. The frame members  121 - 125  may be formed in a hollow configuration, as explained below, for securing the coalescing nets  101 - 104  therein. 
         [0017]    The coalescer  100 , in particular, the coalescing nets  101 - 104 , serve to coalesce relatively fine mist, droplets, fog, and moisture from an air flow entering through a front side of the coalescer  100  in the direction indicated by the arrows  115 . As the coalescing nets  101 - 104  become wet with water as more moisture is trapped, the water is gravitationally removed from the coalescing nets  101 - 104  by a draining movement of the water downward toward the bottom of the coalescing nets  101 - 104 . The coalescing nets  101 - 104  permit dust to pass through, however, and thus do not become easily clogged. Where dust is captured by the coalescing nets  101 - 104 , it is carried toward the bottom of the coalescing nets  101 - 104  by the water draining downward. 
         [0018]    As shown in  FIGS. 1-3 , coalescing nets  101 - 104  are attached at their edges to the frame  105 . With reference in particular to  FIG. 1 , the coalescing nets  101 - 104  may be attached to the frame members  121 - 125  by means of outside tabs  107 ,  108 , and inside tabs  109 ,  110  that are attached to corresponding edges of the coalescing nets  101 - 104  to form first and second coalescing net assemblies. The first coalescing net assembly comprises outside tab  107  and inside tab  109  attached to coalescing net  101  together with outside tab  108  and inside tab  110  attached to coalescing net  103 . The second coalescing net assembly comprises outside tab  107  and inside tab  109  attached to coalescing net  102  together with outside tab  108  and inside tab  110  attached to coalescing net  104 . Thus, each of the first and second coalescing net assemblies is disposed across the first and second frame openings  119 ,  120 . The first coalescing net assembly may be said to have a first portion disposed across the first frame opening  119  and a second portion disposed across the second frame opening  120 . Similarly, the second coalescing net assembly may be said to have a first portion disposed across the first frame opening  119  and a second portion disposed across the second frame opening  120 . 
         [0019]    The outside tabs  107 ,  108  are inserted into the hollow side frame members  123 ,  124 , respectively, and the inside tabs  109 ,  110  are inserted into the hollow crossmember  125 . Similarly, although not shown, top and bottom edges of the coalescing nets  101 - 104  are attached to tabs that are inserted into the top and bottom frame members  121 ,  122 . The side frame members  123 ,  124  include protrusions  111 ,  114  therein for locking the tabs  107 ,  108 , respectively, in place inside the side frame members  123 ,  124 . The crossmember  125  includes similar protrusions  112 ,  113  therein, for locking the tabs  109 ,  110 , respectively, in place inside the crossmember  125 . Similarly, although not shown, top and bottom frame members  121 ,  122  include protrusions for locking the tabs that are attached to the top and bottom edges of the coalescing nets  101 - 104 . Thus, the first and second coalescing net assemblies comprising the coalescing nets  101 - 104  attached to tabs  107 - 110  are fastened to the frame members  121 - 125  for securing the coalescing nets  101 - 104  in the air flow indicated by arrows  115 . In particular, the coalescing nets  101 - 104  are held in position when the coalescing nets  101 - 104  are under tension caused by the incoming airflow. In the exemplary embodiments of  FIGS. 1-3 , the coalescer  100  does not leave significant gaps, such as between the coalescing nets  101 - 104  and the frame  105 , wherein the air flow indicated by arrows  115  might bypass the coalescing nets  101 - 104 . 
         [0020]    The coalescing nets  101 - 104  may be said to have a width and height that is greater than the frame width  117  and frame height  118  to provide a coalescer that allows the coalescing nets  101 - 104  to billow when air flows through the coalescer  100 . The coalescing nets  101 - 104  are secured to the frame members  121 - 125  such that the coalescing nets  101 - 104  are permitted to billow and move independently within the airflow, indicated by arrows  115 , traveling therethrough. The coalescing nets  101 - 104  may each be secured to the frame members  121 - 125  under similar tension or under different tensions. In order to maintain a separation between the coalescing nets  101  and  102 , and between the coalescing nets  103  and  104 , and thereby improve their coalescing capacity, coalescing net  101  comprises less material along its height and width as compared with the coalescing net  102 . Similarly, coalescing net  103  comprises less material along its height and width as compared with the coalescing net  104 . Thus, the area of coalescing net  102  is greater than the area of coalescing net  101 , and the area of coalescing net  104  is greater than the area of coalescing net  103 . It follows then, that the areas of coalescing nets  101 ,  102  are each greater than the area of frame opening  119 , and the areas of coalescing nets  103 ,  104  are each greater than the area of frame opening  120 . In one embodiment, the coalescing nets  101 - 104  each comprise an area that is greater than the area of its corresponding frame opening  119 ,  120  by at least about 150%. 
         [0021]    A person skilled in the art will appreciate that the coalescer  100  may have various configurations other than those shown in  FIGS. 1-3 . For example, the coalescer  100  may include only one coalescing net across each of the frame openings  119 ,  120 , such as coalescing nets  101  and  103 , which comprise the first coalescing net assembly, as described above. The coalescer  100  may, alternatively, include three or more coalescing nets across each frame opening  119 ,  120 , which would comprise three or more coalescing net assemblies. The coalescing nets  101  and  103  may also be formed as one single continuous coalescing net spanning the frame area  116  from side frame member  123  to side frame member  124 . Such a single continuous coalescing net may be secured in fixed contact to a front side or back side of the crossmember  125 , or it may, alternatively, not be in fixed contact with the crossmember  125  and may freely slide over the front side of the crossmember  125 , for example. Similarly, the coalescing nets  102  and  104  may be formed as one single continuous coalescing net spanning the frame area  116  from side frame member  123  to side frame member  124  in fixed or non-fixed contact with the crossmember  125 . 
         [0022]    Moreover, the coalescer  100  may include two or more crossmembers  125  connected to the top and bottom frame members  121 ,  122  to form three or more frame openings similar to the frame openings  119 ,  120 . Each of those frame openings may have one or more coalescing net assemblies disposed thereacross. The coalescing nets  101 - 104  may be attached to frame members  121 - 125  using suitable means other than the locking tabs  107 - 110  described herein. For example, the frame members  121 - 125  may be formed from solid rods and the coalescing nets  101 - 104  may be attached thereto using adhesives, ties, or other suitable fastening means. Thus, the coalescer  100  may include any combination of features disclosed herein and known in the art. 
         [0023]    With reference to  FIGS. 4-6 , a coalescer  200  is provided as an upstream air treatment assembly for a gas turbine or other industrial application requiring moisture filtration. The coalescer  200  includes a frame  207  having parallel top and bottom frame members, or panels,  213 ,  214  attached to parallel side frame members, or panels,  215 ,  216 . The top and bottom frame members  213 ,  214  are attached to the side frame members  215 ,  216  at their ends to form a substantially rigid or semi-rigid frame  207  made from, for example, a plastic or metal. The frame  207  surrounds a frame intake area  208  generally defined by a frame height  209  and a frame width  210 . The frame  207  also comprises a frame depth  211 . The coalescer  200  includes exterior crossmembers  202 ,  204  and interior crossmembers  205  that are each connected to the top and bottom frame members  213 ,  214 , across the intake area  208  between the side frame members  215 ,  216 . The interior crossmembers  205  divide the frame intake area  208  into three frame openings  240 ,  241 ,  242 . Coalescing nets  221 ,  222  are attached to the exterior crossmembers  202 ,  204 , thereby forming first and second coalescing net assemblies across the frame openings  240 - 242  in the frame area  208 . The coalescing nets are in non-fixed contact with interior frame members  205  as an air flow indicated by arrows  212  travels therethrough. This allows the coalescing nets  221 ,  222  to slide across the front side of the interior crossmembers  205 . 
         [0024]    The coalescer  200 , in particular, the coalescing nets  221 ,  222 , serve to coalesce relatively fine mist, droplets, fog, and moisture from an air flow entering through a front side of the coalescer  200  in the direction indicated by arrows  212 . As the coalescing nets  221 ,  222  become wet with water as more moisture is trapped, the water is gravitationally removed from the coalescing nets  221 ,  222  by a draining movement of the water downward toward the bottom edges  235  of the coalescing nets  221 ,  222 . The coalescing nets  221 ,  222  permit dust to pass through, however, and thus do not become easily clogged. Where dust is captured by the coalescing nets  221 ,  222 , it is carried toward the bottom edges  235  of the coalescing nets  221 ,  222  by the water draining downward. 
         [0025]    As shown in  FIGS. 4-6 , the coalescing nets  221 ,  222  are attached at their vertical edges to the exterior crossmembers  202 ,  204 . With reference in particular to  FIG. 4 , the coalescing nets  221 ,  222  may be attached to exterior crossmembers  202 ,  204  by forming a coalescing net loop  201 ,  203  at each of the vertical edges of the coalescing nets  221 ,  222  and wrapping the coalescing net loops  201 ,  203  around the exterior crossmembers  202 ,  204 , respectively, as shown in  FIG. 4 , to form first and second coalescing net assemblies. The first coalescing net assembly comprises exterior crossmembers  202 ,  204  attached to coalescing net  221 . The second coalescing net assembly comprises exterior crossmembers  202 ,  204  attached to coalescing net  222 . Thus, each of the first and second coalescing net assemblies is disposed across the three frame opening  240 - 242 . The first coalescing net assembly may be said to have a first portion disposed across the frame opening  240 , a second portion disposed across the frame opening  241 , and a third portion disposed across the frame opening  241 . Similarly, the second coalescing net assembly may be said to have a first portion disposed across the frame opening  240 , a second portion disposed across the frame opening  241 , and a third portion disposed across the frame opening  241 . 
         [0026]    The coalescing nets  221 ,  222  generally comprise a width that is about three times the width  210  of the frame  207 . The coalescing nets  221 - 222  may be said to have a width that is greater than the frame width  210  to provide a coalescer that allows the coalescing nets  221 - 222  to billow when air flows through the coalescer  200 . The coalescing nets  221 - 222  may each be secured to the external crossmembers  202 - 204  under similar tension or under different tensions. In order to maintain a separation between the coalescing nets  221  and  222 , and thereby improve their coalescing capacity, coalescing net  221  comprises less material along its width as compared with the coalescing net  222 . Thus, the area of coalescing net  222  is greater than the area of coalescing net  221 . It follows then, that the areas of coalescing nets  221 ,  222  are each greater than the frame area  208 . Also, the areas of the first, second, and third portions of each of the coalescing nets  221 ,  222  are greater than the areas of the corresponding frame openings  240 - 242 . In one embodiment, the coalescing nets  221 - 222  each comprise an area that is greater than the frame area  208  by at least about 200%. 
         [0027]    While the coalescing nets  221 ,  222  are permitted to move freely within the frame  207 , the height  209  of the frame  207  is selected to minimizes a gap  232  as between the top edges  234  of the coalescing nets  221 ,  222  and the interior top surface  230  of the frame  207 , as well as minimize a gap  233  as between the bottom edges  235  of the coalescing nets  221 ,  222  and the interior bottom surface  231  of the frame  207 . The crossmembers  202 - 205  secure the coalescing nets  221 ,  222  in position within the air flow indicated by arrows  212 . In particular, when the coalescing nets  221 ,  222  are under tension caused by the incoming airflow, the coalescing nets  221 ,  222  may be free to billow and move independently within the frame  207 . In one embodiment, the sizes of the coalescing nets  221 ,  222  and the frame depth  211  are configured such that the coalescing nets  221 ,  222  do not billow beyond the frame depth  211 . The coalescing nets  221 ,  222  may be in non-fixed contact with the interior crossmembers  205  or they may be in fixed contact with the interior crossmembers  205  by attaching them to the interior crossmembers  205  along the height of the coalescing nets  221 ,  222  and along the height of the crossmembers  205 , such as by clamping, tying, or hooking the coalescing nets  221 ,  222  thereto. 
         [0028]    A person skilled in the art will appreciate that the coalescer  200  may have various configurations other than those shown in  FIGS. 4-6 . For example, the coalescer  200  may include only one coalescing net across each of the frame openings  240 - 242 , such as coalescing net  221 , which is comprised in the first coalescing net assembly. The coalescer  200  may, alternatively, include three or more coalescing nets across each frame opening  240 - 242 , which would comprise three or more coalescing net assemblies. The coalescing nets  221 ,  222  may also be formed as separate pieces each spanning a single one of the frame openings  240 - 242  and attached between interior crossmembers  205 , for example, or between an interior crossmember  205  and an exterior crossmember  202 ,  204 . 
         [0029]    Moreover, the coalescer  200  may include only one interior crossmember  205  connected to the top and bottom frame members  213 ,  214  to form two frame openings similar to the frame openings  240 - 242 . Each of those frame openings may have one or more coalescing net assemblies disposed thereacross. The coalescing nets  221 - 222  may be attached to exterior crossmembers  202 ,  204  using suitable means other than the coalescing net loops  201 ,  203  described herein. For example, the coalescing nets  221 - 222  may be attached thereto using adhesives, ties, hooks, clamps, or other suitable fastening means. In addition, the coalescer  200  may include three or more interior crossmembers  205 , wherein each of the additional interior crossmembers  205  supports the one or several coalescing nets  221 ,  222  as described herein. Thus, the coalescer  200  may include any combination of features disclosed herein and known in the art. 
         [0030]    As illustrated herein, the coalescing assemblies  100 ,  200  may be positioned in a conduit of an air treatment system for de-moisturizing air to be used in downstream industrial applications, such as a gas turbine. The frame  105  of the coalescer  100  may be sealingly positioned in an opening of a single conduit, or in a frame containing a plurality of openings within which a number of coalescers  100  may be disposed. Similarly, the frame  207  of the coalescer  200  may be positioned in an opening of a single conduit or in a system of coalescing assemblies  200 . 
         [0031]    The coalescing nets  101 - 104  and  221 ,  222  described above with respect to coalescing assemblies  100 ,  200 , respectively, may be formed of a raschel weave, or raschel knit, having a lacelike, open construction of a relatively heavy, textured yarn held in place by a much finer yarn, a shade net type with shading values from about 35% to about 80%, for example, or similar net types. Air flow through the coalescing nets  101 - 104 ,  221 ,  222 , may cause a relative movement as much as half the height or length thereof, and may lead to a billowing, wave-like or turbulent movement of the coalescing nets  101 - 104 ,  221 ,  222 . 
         [0032]    The coalescing of moisture may occur at either or all of the coalescing nets  101 - 104  or  221 ,  222 . The frame  105 , and its crossmember(s)  125 , which secure the coalescing nets  101 - 104  may be disposed substantially perpendicularly with respect to a predominant direction of the airflow indicated by arrows  115 . Similarly, the frame  207 , its interior crossmembers  205 , and its exterior crossmembers  202 ,  204 , which secure the coalescing nets  221 ,  222 , may be disposed substantially perpendicularly with respect to a predominant direction of the airflow indicated by arrows  212 . In some embodiments, the coalescing nets  101 - 104  and  221 ,  222  may be disposed at another angle with respect to the airflows, but sufficiently vertical whereby gravitational drainage of coalesced moisture is encouraged and/or facilitated. 
         [0033]    In view of the foregoing, embodiments of the invention provide an efficient moisture removal assembly without causing an excessive pressure drop in the incoming air flows. A technical effect is to provide demoisturized air for improved performance of industrial machinery, such as gas turbines. 
         [0034]    This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.