Abstract:
A water deaerating system and method are provided. The first end of an open-ended conduit is placed beneath the surface of a body of oxygen-rich water. The conduit extends into a housing and where the second end of the conduit resides at a location in the housing that is above the surface of the body of oxygen-rich water. A vacuum is applied to a spatial region defined within the housing above the location of the second end of the conduit. The oxygen-rich water is pumped through the conduit and exits the second end of the conduit to enter the spatial region of the housing. The oxygen-rich water descends through the housing due to gravity. The oxygen-rich water&#39;s descension is interrupted and the vacuum operates to remove oxygen from the oxygen-rich water so-descending to generate oxygen-depleted water.

Description:
ORIGIN OF THE INVENTION 
       [0001]    Pursuant to 35 U.S.C. §119, the benefit of priority from provisional application 61/000,103, with a filing date of Oct. 23, 2007, is claimed for this non-provisional application. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates generally to deaerating systems, and more particularly to a deaerating system that can be placed at the front end of a cooling water intake line and be used to control/prevent the colonization of aquatic species (e.g., zebra mussels) within the cooling water intake line. 
       BACKGROUND OF THE INVENTION 
       [0003]    Zebra mussels are small bivalve creatures that live in large densities in rivers and lakes in North America and Europe. They attach themselves to any hard surface using adhesive byssal threads. Zebra mussels are particularly problematic for electric power plants or any industrial plant that draws its cooling water directly from a nearby river or lake. The zebra mussels are drawn from the river/lake by the cooling water delivery system and ultimately end up in cooling water pipes. Left unchecked, the zebra mussels attach themselves to the delivery system and/or cooling water pipes&#39; inner walls. As the colonies of zebra mussels grow on/in the systems and/or pipe walls, cooling water flow decreases. Reduction in cooling water can lead to power outrages and/or equipment failures. Currently, industry employs various post-colonization procedures to remove the zebra mussels from the inner walls of cooling water intake pipes. These methods typically involve the use of chemical biocides that, unfortunately, can be toxic to local non-harmful organisms and/or deposit/produce substances that may be carcinogenic. 
       SUMMARY OF THE INVENTION 
       [0004]    Accordingly, it is an object of the present invention to provide a system and method that prevent the colonization of zebra mussels on the inside walls of cooling water intake pipes. 
         [0005]    Another object of the present invention is to provide a system and method that treats a plant&#39;s cooling water to prevent zebra mussel colonization in the cooling water system without harming other local species. 
         [0006]    Still another object of the present invention is to provide a system and method that treats a plant&#39;s cooling water to prevent zebra mussel colonization in the cooling water system without the use of chemical biocides. 
         [0007]    Other objects and advantages of the present invention will become more obvious hereinafter in the specification and drawings. 
         [0008]    In accordance with the present invention, a water deaerating system and method are provided. The first end of an open-ended conduit is placed beneath the surface of a body of oxygen-rich water. The conduit extends into a housing and where the second end of the conduit resides at a location in the housing that is above the surface of the body of oxygen-rich water. A spatial region is defined within the housing above the location of the second end of the conduit. A vacuum source coupled to the housing applies a vacuum to the spatial region. The oxygen-rich water is pumped through the conduit so that the oxygen-rich water exits the second end of the conduit and enters the spatial region of the housing. The oxygen-rich water entering the spatial region then descends through the housing due to gravity. Beneath the spatial region are obstructions or interruptions that interrupt the oxygen-rich water&#39;s descension through the housing. The vacuum operates to remove oxygen from the oxygen-rich water so-descending through the housing to generate oxygen-depleted water. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    Other objects, features and advantages of the present invention will become apparent upon reference to the following description of the preferred embodiments and to the drawings, wherein corresponding reference characters indicate corresponding parts throughout the several views of the drawings and wherein: 
           [0010]      FIG. 1  is a schematic view of an open-circuit, in-line deaerating system for use with the front end of a cooling water system in accordance with an embodiment of the present invention; 
           [0011]      FIG. 2  is a top view of a portion of an embodiment of a ledge disposed in the deaerating system; 
           [0012]      FIG. 3  is an end view of a portion of another embodiment of a ledge disposed in the deaerating system; 
           [0013]      FIG. 4  is a schematic view of a closed-circuit, in-line deaerating system in accordance with another embodiment of the present invention; 
           [0014]      FIG. 5  is a schematic view of an in-line deaerating system using upward canted ledges in accordance with another embodiment of the present invention; 
           [0015]      FIG. 6  is an isolated plan view of the housing and conduit in accordance with another embodiment of the present invention; and 
           [0016]      FIG. 7  is an isolated plan view of the housing and conduit in accordance with still another embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]    Referring now to the drawings, and more particularly to  FIG. 1 , an in-line deaerating system in accordance with the present invention is shown and is referenced generally by numeral  10 . Deaerating system  10  will typically be located at or near the shore  100  of a river or lake  200 , and be coupled to the front end of a cooling water intake pipe  300  that leads to a cooling water system (not shown). It is to be understood that cooling water intake pipe  300  and the cooling water system are not part of, or limitations on, the present invention. Accordingly, cooling water intake pipe  300  is illustrated by dashed lines to clearly delineate it from deaerating system  10 . The cooling water system could be one used by a power plant or any other type of industrial facility without departing from the scope of the present invention. 
         [0018]    Deaerating system  10  has an enclosed columnar housing  12  with its base  12 A mounted on shore  100  or embedded in shore  100  as illustrated. Centrally disposed in housing  12  is an open-ended conduit  14  that is vertically oriented in the illustrated embodiment such that an annular region is formed between the inner walls of housing  12  and the outer walls of conduit  14 . The cross-sectional geometries of housing  12  and conduit  14  can be the same or different, and can be circular, rectangular, regular, irregular, etc., without departing from the scope of the present invention. One open end  14 A of conduit  14  is coupled to an open-ended intake conduit  16  that leads into river or lake  200 . The other open end  14 B of conduit  14  resides in housing  12  at a selected height H above the surface  200 A of river or lake  200  such that a space  18  is defined above open end  14 B. Open end  14 B can be directed upward (as shown) in a direction substantially parallel to the force of gravity. However, the present invention is not so limited as open end  14 B could also be angularly oriented with respect to the force of gravity. 
         [0019]    Positioned in conduit  14  is an impeller  20  that, when rotated by a drive motor  22  (via a rotating shaft  24 ), pulls raw water  202  from river/lake  200  into and through intake conduit  16  and conduit  14  in the direction indicated by flow arrows  204 . It is to be understood that impeller  20  could be disposed at other locations in conduit  14  or in conduit  16  without departing from the scope of the present invention. Accordingly, the location of motor  22  is also not limited to the illustrated location thereof. In addition, impeller  20  and motor  22  could be an integrated assembly in which case they could be co-located. Still further, the functions provided by impeller  20  and motor  22  could be achieved using other devices/systems as would be understood by one of ordinary skill in the art. 
         [0020]    A vacuum source  26  is coupled to the internal portion of housing  12  at one or more regions thereof above open end  14 B of conduit  14  such that vacuum source  26  is in communication with space  18 . The vacuum applied to space  18  is contained by housing  12  or by the combination of housing  12  and the water that collects at the base of housing  12  as will be explained further below. 
         [0021]    Disposed about the external periphery of conduit  14  are a series of annular ledges  30 . In this embodiment, each annular ledge  30  is angled or sloped towards the surface  200 A of river/lake  200 . Disposed about the internal periphery of housing  12  are a series of annular ledges  32 . Each annular ledge  32  is also angled or sloped towards the surface  200 A of the river/lake  200 . By sloping ledges  30  and  32  in this fashion, water striking the top surfaces of ledges  30  and  32  briefly adheres thereto owing to surface tension, but then is shed therefrom under the force of gravity. Annular ledges  30  and  32  are staggered or interleaved in terms of their vertical position as illustrated for reasons that will be explained further below. 
         [0022]    Each of ledges  30  and  32  can present a solid, flat surface. However, the present invention is not so limited. For example, as illustrated in a partial top view of a single ledge  30  shown in  FIG. 2  having a perimeter geometry that corresponds to the outer surface of conduit  14 , through holes  30 A can be provided in ledge  30  thereby making the ledge porous. The ledges could also present an uneven surface such as the ribbed or undulating surface  30 B illustrated in the partial end view of a single ledge  30  shown in  FIG. 3 . Ledges  32  could be similarly constructed/configured. Further, ledges  30  and  32  can be constructed differently and/or be canted towards the surface  200 A at different angles without departing from the scope of the present invention. 
         [0023]    In operation, impeller  20  is turned (via motor  22 /shaft  24 ) to generate flow  204  of raw water  202 . At the same time, vacuum source  26  applies a vacuum to space  18  in order to evacuate same. As raw water  202  spills annularly out of open end  14 B of vertical conduit  14  (as indicated by flow arrows  206 ), the vacuum in space  18  acts on raw water flow  206  to remove dissolved oxygen therefrom. The annular distribution of raw water flow  206  increases the surface area thereof exposed to the vacuum in space  18 . At the same time, earth&#39;s gravity force causes raw water flow  206  to be directed towards the bottom of housing  12  as indicated. 
         [0024]    Housing  12  will typically be made from a material having good compression attributes (e.g., concrete) to insure housing integrity when vacuum source  26  is operated. In order to optimize dissolved oxygen removal, the present invention uses ledges  30  and  32  to interrupt water flow  206  thereby increasing (i) the surface area of raw water flow  206  exposed to the vacuum, and (ii) the time that raw water flow  206  is exposed to the vacuum. With ledges  30  and  32  arranged in a staggered/stepped vertical relationship as shown, the raw water flows in a stepped fashion as indicated by flow arrows  206 A. As a result, oxygen-depleted water  208  is deposited about the bottom of conduit  14 . From here, oxygen-depleted water  208  is available for entry into intake pipe  300  where it can be drawn for use by the cooling water system (not shown) coupled to intake pipe  300 . 
         [0025]    The advantages of the present invention are numerous. By removing dissolved oxygen from the raw water flow, the present invention provides a supply of oxygen-depleted cooling water that will not support the growth and colonization of zebra mussels. The oxygen-depleted cooling water also reduces the zebra mussels&#39; ability to attach to the walls of the intake pipe thereby casuing them to simply be transported along intake pipe  300  (in the direction indicated by flow arrow  210 ) for easy filtering/removal by existing cooling water system filtration mechanisms. This eliminates the need to “scrub” intake pipe  300 . Further, the present invention achieves its prevention approach in an environmentally-friendly fashion since no chemical biocides are used. 
         [0026]    The present invention is not limited to the open-circuit deaerating system presented in  FIG. 1 . Indeed, another variation of the present invention uses closed-loop control of motor  22  and/or vacuum source  26 . Such a closed-loop system is illustrated in  FIG. 4  where an oxygen sensor  40  is disposed in oxygen-depleted water  208 . Multiple oxygen sensors could also be used without departing from the scope of the present invention. The output of oxygen sensor  40  is supplied to a controller  42  programmed to monitor the oxygen content detected by sensor  40 . The oxygen content is then used in a control algorithm to control operation of motor  22  and/or vacuum source  26 . The control algorithm would typically be governed by an oxygen content of approximately  4  parts per million (ppm) since oxygen levels in water must generally be maintained below this level to ensure zebra mussel population control as well as reduce the zebra mussels&#39; ability to attach themselves to walls. 
         [0027]    The present invention is also not limited to the use of downward-canted ledges as illustrated by the embodiment shown in  FIG. 5  where ledges  30  and  32  are canted upwards. Thus, gravity will cause each ledge to form a pooling area that temporarily fills with raw water  206  before spilling down onto the next ledge as indicated by flow arrows  206 A. In this way, the amount of time that raw water  206  is exposed to the vacuum (applied by vacuum source  26 ) is further increased. 
         [0028]    Maintenance of the present invention can be enhanced by making conduits  14  and  16  in modular sections since these conduits are exposed to raw, oxygen-rich water with zebra mussels. In this way, if a section of these conduits becomes “coated” with zebra mussels, the affected section can be quickly removed/replaced. Further, the present invention can incorporate a bypass feature (not shown) that allows raw water  202  to bypass the deaerating system to thereby provide for system maintenance and/or bypass of the system when the zebra mussel population is decreased (e.g., when the raw water is cold). 
         [0029]    Although the invention has been described relative to specific embodiments thereof, there are numerous variations and modifications that will be readily apparent to those skilled in the art in light of the above teachings. For example, the ledges in the present invention could be positioned horizontally, or replaced, changed and/or complemented with other devices or structures that increase the amount of time that raw water  206  is exposed to the vacuum and/or increase the surface area of raw water  206  that is exposed to the vacuum as the raw water cascades down through housing  12 . Further, in some applications, conduit  14  could be located adjacent to an inner wall of housing  12  in which case a substantially annular region would be defined about conduit  14  as illustrated in  FIG. 6  where just the housing and conduit are shown in a plan view. Still other applications may only require open end  14 B of conduit  14  to pass through a side wall of housing  12  (as shown in the  FIG. 7  plan view) and be located in housing  12  at a location above the surface  200 A of river/lake  200 . It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described.