Abstract:
A clarifier support structure for supporting tube or plate modules in a clarifier tank or basin is disclosed together with a method for installing the structure in a tank or basin. The structure comprises a first laterally extending truss supported on first and second opposed walls of the tank, a longitudinally extending truss supported at one end on the laterally extending truss and at a second end on a transversely extending wall of the tank, a first module support member supported at its ends on the first opposed side wall and on said longitudinally extending truss, and a second module support member supported at its ends on the second opposed side wall and on said longitudinally extending truss.

Description:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0001]    Not applicable. 
       THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT 
       [0002]    Not applicable. 
       REFERENCE TO A “SEQUENCE LISTING,” A TABLE, OR A COMPUTER PROGRAM LISTING APPENDIX 
       [0003]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0004]    1. Field of the Invention 
         [0005]    This invention is in the field of large scale clarification systems for settling solids out of continuously flowing water or other liquid. Such systems are frequently employed in municipal and industrial water treatment systems. 
         [0006]    2. Description of the State of the Art 
         [0007]    Municipal and industrial water treatment clarification systems generally comprise some type of settling tank or basin with a gravity sedimentation system for removing solids from water or other liquid. Such tanks are, generally speaking, either circular or rectangular. This invention is particularly concerned with generally rectangular settling tanks although many features of the invention translate nicely into clarifiers involving circular tanks. Such tanks are typically built above ground or partially above ground. The settling tanks have a floor or bottom, an inlet and an outlet and they are generally open on top. Rectangular tanks also include a front wall, a rear wall and side walls. Typically, these tanks are made of concrete or steel. 
         [0008]    During the operation of a clarification system, a liquid enters the settling tank through an inlet near the front wall and is directed generally horizontally in a longitudinal direction towards an outlet near the rear wall of the tank. The efficiency of a clarification system is greatly enhanced when an array of tube or plate modules (“modules”) is provided in a settling tank. These modules comprise a series of tubes or plates or the like and they are typically located near the outlet of the tank, preferably above and spaced from the tank floor. Liquid flowing through a settling tank provided with an array of modules is directed generally upwardly through the array of modules towards an outlet. In these types of clarification systems, the array of modules is supported in the settling tank by a clarifier support structure. 
         [0009]    The modules increase the efficiency of clarifiers so that flow through rates can be increased substantially with improved effluent quality. The modules enhance the rate at which suspended solids are separated by gravity from the liquid in which they are suspended. The modules contribute to enhanced gravity separation in several ways. Unstable liquid flow patterns and mixing currents inhibit particle settlement rates. These undesirable flow patterns and mixing currents are drastically reduced through the use of modules. All together, the liquid contacting surfaces of the modules provide settling surfaces with a very large total surface area. The settling surfaces in the modules are inclined rather steeply and this reduces the distance that particles have to fall before contacting a settling surface. Once the super fine suspended particles come into contact with a settling surface, the particles begin to agglomerate into larger particles which settle much more rapidly than the fine particles. The enhanced gravity separation that is achieved with modules translates into relatively smaller settling tanks in new units. In existing units, increased flow through rate together with improved effluent quality are realized. 
         [0010]    Liquid flowing upwardly through an array of modules moves very slowly and the liquid is clarified as gravity causes suspended solids to fall or settle towards the floor of the settling tank. The rate of movement of liquid through the modules is very slow, something on the order of three feet per minute or less. Clarified liquid then leaves the settling tank through an outlet which could be comprised of weirs or launders or the like. 
         [0011]    A structure for supporting an array of modules in the upper rear portion of a settling tank should not be supported by or from the settling tank floor. The floor of the settling tank should not be obstructed by the clarifier support structure because sludge collects on the tank floor and the presence of clarifier support structure on or even near the tank floor would interfere with the collection of sludge. Sludge removal systems are provided at the bottom of settling tanks and the clarifier support structure must be designed so that it does not interfere with the sludge removal system. 
         [0012]    In a clarifier support structure for supporting modules in a tank or basin, at least a portion of the support structure will be below the modules and the modules will be supported by that portion. However, the height and size of the support structure should be minimized in order to maximize the unimpeded flow of liquid up and into and through the modules and further, in some cases, in order to provide for the unimpeded operation of sludge removal apparatus below the modules. 
         [0013]    U.S. Pat. No. 5,217,614 discloses a clarifier support structure which comprises an inverted T-shaped truss that is supported within the tank by wall engaging pads or pedestals. The design of the structure disclosed in this patent does a good job of minimizing the presence of elements of the structure that are below the modules. There are some penalties associated with this design, however, in terms of the level of difficulty associated with the installation of the modules. The structure also presents some difficulties attendant to the removal and replacement of individual modules. There are further problems that can arise from portions of the clarifier support structure breaching portions of the modules. 
         [0014]    The present invention has many objects including, but by no means limited to, providing a clarifier support structure that (1) is easy to install in a settling tank, (2) when installed, has only minimal structure that is actually below the individual modules, (3) will not interfere with the collection and removal of sludge from the floor of the settling tank, (4) permits the easy and efficient removal and replacement of individual modules, (5) accommodates and compensates for variations in the width of the tanks and the shortest distance between the two side walls from any given point on one of the side walls, (6) minimizes the problem of liquid flowing around rather than through the modules, and (7) eliminates or minimizes module bypass arising from support structure actually extending into portions of the modules. 
         [0015]    These and other objects and advantages of the present invention shall be apparent from the following detailed description with reference, therein, to the several drawing figures. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0016]      FIG. 1  is a plan view of a settling tank in which there is mounted a clarifier support structure according to the invention; 
           [0017]      FIG. 2  is cross sectional view of the settling tank shown in  FIG. 1 , taken along the line  2 - 2  of  FIG. 1 . 
           [0018]      FIG. 3  is cross sectional view of the settling tank shown in  FIG. 1 , taken along the line  3 - 3  of  FIG. 1 . 
           [0019]      FIG. 4  is a detail view of a truss and a truss wall support in a clarifier support structure according to the invention. 
           [0020]      FIG. 5  is a detail view of a connection between a transverse truss and longitudinal truss in a clarifier support structure according to the invention. 
           [0021]      FIG. 6  is a view, partially in cross section, showing clarifier support members and hangers for supporting the members from a longitudinal truss in the clarifier support structure. 
           [0022]      FIG. 7  is a detail view of a clarifier support member and a clarifier support member wall support in a clarifier support structure according to the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0023]    A clarifier support structure indicated generally at  10  is supported within a settling tank  12  in an upper, rear portion thereof. The tank  12  comprises a front wall  14 , a rear wall  16 , side walls  18  and a floor or bottom  20 . The settling tank  12  is generally open at the top. The clarifier support structure  10  is well suited for use in a newly constructed settling tank and it is also well suited for use in replacing a clarifier support structure in an existing settling tank. 
         [0024]    The clarifier support structure  10  comprises a laterally extending or lateral truss  22  which is supported, at its ends, on the side walls  18 . The lateral truss, in turn, supports one end of a longitudinally extending or longitudinal truss  24 . Longitudinal and lateral refer, here, to the direction of flow of liquid in the settling tank  12  which is indicated by arrows in  FIGS. 1 and 3  and is, generally, towards the rear wall  16  from the front wall  14 . The other end of the longitudinal truss is supported on the rear wall  16 . 
         [0025]    A plurality of module support members  26  is provided and they extend laterally within the tank  12 , substantially parallel to the truss  22 . The support members  26  are supported at one end on the longitudinal truss  24  and, at the other end, on one of the side walls  18 . Thus, the support members  26  only extend one half of the lateral distance between the side walls  18 , thereby drastically reducing the required size and minimum load-bearing capacity of these members  26 . It will be appreciated that, in especially large settling tanks, i.e., tanks having a very long lateral dimension, a second or even a third longitudinal truss can be provided in order to further reduce the required size and minimum load-bearing capacity of the module support members  26 . 
         [0026]    A plurality of tube or plate modules  28  are supported on the module support members  26 . For illustrative purposes only, a single representative module  28  is shown in  FIGS. 1 ,  2  and  3 . Of course, the number of module in a given installation will vary, based upon a consideration of many factors as known by persons of skill in the art. It is important to note, however, that the design of the clarifier support structure is especially suited to maximize the flow of liquid through the modules  28 . As shown in  FIG. 1 , the module  28  that is adjacent to the longitudinal truss  24  (one truss  24  is shown in  FIG. 1 ) snug right up to the truss  24 , thereby preventing liquid from flowing upwardly between the module  28  and the longitudinal truss  24 . Similarly, the module  28  which is adjacent to the lateral truss  22  snug right up to the truss  22 , thereby preventing liquid from leaking, i.e., flowing upwardly between the module  28  and the trusses  22  and  24 . 
         [0027]    A baffle  30  is supported on the main, major, transverse truss  22 . It serves to direct the flow of liquid entering the front of the tank  12  downwardly in order to maximize the flow of liquid into the lower rear portion of the tank  12 , thereby maximizing the flow of liquid upwardly through the modules  28  in the upper rear section of the tank  12 , in indicated by arrows in  FIG. 3 . 
         [0028]    Turning now to the details of the structure which supports the module support members  26 , it will be seen at once that it is remarkable in its engineering elegance. The lynch pin of the support structure is the transverse truss  22 . In the embodiment shown in the drawing figures, the truss  22  is a simple truss with an upper chord  32  and a lower chord  34 . Vertical struts  36  and diagonal struts  38  connect the chords  32  and  34  in a known manner. Of course, other trusses, both known and hereafter developed, may be utilized but there is a preference for trusses with a single upper chord and a single lower chord. 
         [0029]    The truss  22  spans the width of the settling tank  12  between the side walls  18 . In large settling tanks, however, with older concrete side walls, the walls will not be exactly parallel and the shortest distance between them, from any given point on one side wall, can vary significantly and must be accommodated. For this purpose, a wall support comprising a face plate  40  ( FIG. 4 ) and a chord support  42  is provided. The chord support  42  is welded or otherwise connected to the face plate  40  which, in turn, is connected to the side wall  18  as by fasteners such as the threaded fasteners indicated at  44 . Details of this construction are seen in  FIG. 4 . The chord  32  does not reach all the way to the face plate  40  and this is intended. It facilitates the in-situ erection of the clarifier support unit. The face plate  40  with the chord support  42  for the upper chord  32  is connected to a side wall  18  and a second face plate  40  (shown in  FIG. 3 ) for the lower chord  34  is secured to the same side wall  18 . The same face plate and chord connector arrangement is made on the opposed side wall  18  (see  FIG. 1 ). 
         [0030]    The in-situ erection of the clarifier support can begin with the truss  22  and the step of securing the face plates  40  with chord supports  42  attached thereto at the desired positions on the side walls  18 . With the face plates  40  and chord supports  42  in place, the truss  22  is maneuvered into a position in which a first end  46  of the upper chord  32  and a first end  48  of the lower chord  34  are supported by the chord supports  42  ( FIG. 2 ). The ends  46  and  48  of the upper and lower chords  32  and  34  of the truss  22  are then moved towards the face plates  40 . The lengths of the truss  22  and the lengths of the chord supports  42  are controlled so that, when the first ends  46  and  48  of the chords  32  and  34  are touching the corresponding face plates  40 , the opposed ends of the chords  32  and  34  do not reach the corresponding chord supports on the opposite side wall  18 . The lengths of the truss  22  and the lengths of the chord supports  42  may also be controlled so that, when the first ends  46  and  48  of the chords  32  and  34  are touching the corresponding side wall  18 , the opposed ends of the chords  32  and  34  do not reach the corresponding chord supports on the opposite side wall The truss  22  is then maneuvered to align the other ends of the chords  32  and  34  with the chord supports  42  supported on face plates  40  on the opposite side wall  18 . The truss  22  is moved (from left to right in  FIG. 2 ) towards the face plates  40  of the chord supports  42  on the opposite side wall  18  until both ends of the chords  32  and  34  are supported by portions of all four chord supports  42 . The position of the truss  22  relative to the chord supports  42  is then adjusted so that, as nearly as is practical, the ends of the chords  32  and  34  are supported on the four chord supports  42  so that approximately equal lengths of the ends of the chords  32  and  34  are engaged with the four chord supports  42 . When the adjustment is completed, the position of the truss  22  is fixed, for example, by threaded fasteners  50 , one of which is shown in  FIG. 4 , which extend through apertures in the chord supports  42  and the ends of the chords of the truss  22 . Fasteners  50  may be provided at one or both ends of the chords  32  and  34 . 
         [0031]    The in-situ erection of the clarifier support can continue with the truss  24 . One end of the truss  24  is going to be supported on the rear wall  16  and the other end of the truss  24  is going to be supported directly on the main lateral truss  22 . The truss  24  is similar to the truss  22  although, typically, truss  22  will be longer and taller than truss  24 . The truss  24  comprises an upper chord  52  and a lower chord  54  and they are connected by vertical struts  56  and diagonal struts  58 . The upper and lower chords  52  and  54  have first ends  60  and  62  which will be supported on the rear wall  16  in a manner similar to the manner in which the ends of the lateral truss  22  are supported on the side walls  18 . The first ends  60  and  62  of the upper and lower chords  52  and  54  are aligned with chord supports  64  on face plates  66  which have been attached to the rear wall  16  in desired positions. The ends  60  and  62  of the chords  52  and  54  are advanced towards the face plates  66  so that the first end of the truss  24  is supported at the rear wall  16  of the tank  12 . 
         [0032]    The upper and lower chords  52  and  54  of the truss  24  have second ends  68  and  70 , respectively, and they are supported on the lateral truss  22 . In the embodiment illustrated in the drawing figures, second end  70  of lower chord  54  of truss  24  is connected to the lower chord  34  of the lateral truss  22  and, as can be seen in  FIG. 3 , the second end  68  of chord  52  is connected to a major vertical strut  72  in the truss  22 . Suitable connections are described below and illustrated in the drawing figures. However, myriad other connections, known to persons skilled in this art, are also suitable. 
         [0033]    As shown in  FIG. 5 , an end plate  74  is welded or otherwise secured to the second end  70  of the lower chord  54  of the longitudinal truss  24 . Upper and lower end plate brackets  76  and  78  are welded or otherwise secured to the lower chord  34  of the truss  22 . Portions of the end plate  74  are parallel to and can be aligned with corresponding portions of the upper and lower brackets  76  and  78 . The longitudinally adjustable connections between the first ends  60  and  62  of the chords  52  and  54 , and the chord supports  64 , facilitate the alignment of the end plate  74  and the brackets  76  and  78 . Threaded fasteners  80  connect the end plate  74  to the brackets  76  and  78 . A similar connection between the upper chord  52  of truss  24  and the major vertical strut  72  of truss  22  is made involving an end plate  82  ( FIG. 3 ) on chord  52  which is fastened to an end plate bracket(s)  84  that is secured to the strut  72 . 
         [0034]    With the trusses  22  and  24  secured to and supported in the tank  12 , the erection of the clarifier support structure continues with the module support members  26 . In an installation in which there is but one longitudinal truss, one end of each module support member  26  is connected to and supported on a side wall  18  and the other end of each module support member  26  is connected to and supported on the longitudinal truss  24 . In an installation in which there is more than one longitudinal truss, both ends of some of the module support members  26  will be connected to and supported by two longitudinal trusses. Suitable connections between module support members  26  and tank side walls  18 , as well as connections between module support members  26  and a longitudinal truss  24  are described below with particular reference to  FIGS. 6 and 7 . Again, myriad other connections, known to persons skilled in this art, are also suitable. 
         [0035]      FIG. 6  is a view looking down the lower chord  54  of the longitudinal truss  24  towards the lower chord  34  of the lateral truss  22 . A hanger connector  86  is secured, as by welding, to the lower chord  54  of the longitudinal truss  24 . The hanger connector  86  is a t-shaped beam with two flanges  88  and  90  which extend outwardly from a central web  92  towards the side walls  18  of the tank  12 . A lateral end flange  94  extends outwardly from each of the support members  26 . The end flange  94  is part of an L beam and the other flange  96  of the L beam is secured, as by welding or the like, to the end of each of the module support members  26  shown in  FIG. 6 . When the flange  94  extending from an end of one of the support members  26  rests on one of the two flanges  88  and  90 , that end of that support member  26  is supported by the longitudinal truss  24  through the hanger  86 . The flange  94  is secured to one of the flanges  88  and  90  as by a threaded connector  98  or the like. The other end of that support member would then be supported either in a similar manner on an adjacent longitudinal truss, if there be such, or at one of the side walls  18  in a manner such as the one illustrated in  FIG. 7 . 
         [0036]    A side wall support for a support member  26  is illustrated in  FIG. 7 . The member  26  has a wall end  100  which is aligned with a support member support  102  on a face plate  104  which has been attached, as by threaded fasteners  106  to the side wall  18 . The wall end  100  of the support member  26  is advanced towards the face plate  104  so that the wall end  100  of the support member  26  is supported at the side wall  18  of the tank. The support member  26  is then manipulated, while the wall end  100  is supported by the support member support  102 , until the flange  94  at the opposite end of the support member  26  is supported on the longitudinal truss  24  as by way the hanger connector  86 , as shown in  FIG. 6 , or the like. A threaded connector such as the connector  98  is used to connect the flange  94  to one of the flanges  88  and  90 , as shown in  FIG. 6 . This will fix the longitudinal position of the wall end  100  of the member  26  relative to the member support  102  although it may be desired to further fix the longitudinal position of the support member  26  by connecting the end  100  to the support member support  102 , as by a threaded connector (not shown). 
         [0037]    It will be apparent to the artisan that the present invention is susceptible of numerous variations from the details described above and illustrated in the various drawing figures. Therefore, notice is hereby given that the invention is not to be limited by the foregoing description but only in light of the spirit and scope of the invention as defined in the claims appended hereto.