Abstract:
A method for the treatment of water used in a cooling tower, the method including the steps of withdrawing a portion of the water from a basin of the cooling tower, subjecting the water to a magnetic treatment, and withdrawing blow down water for use in irrigation.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to water treatment and more particularly, relates to a water treatment system and a method for utilizing blow down water for irrigation. 
       BACKGROUND OF THE INVENTION 
       [0002]    Cooling towers are basically heat removal devices used to transfer processed waste to heat the atmosphere. Cooling towers may either use the evaporation of water to remove processed heat and cool the working fluid to near the wet-bulb air temperature or rely solely on air to cool the working fluid to near the dry-bulb air temperature. Common applications include cooling the circulating water used in oil refineries, chemical plants, power stations, building cooling, etc. The towers vary in size from small roof-top units to very large structures that can be as much as 200 meters tall and 100 meters in diameter. 
         [0003]    Cooling towers can be classified into different types—HVAC (air conditioning) or industrial duty. An HVAC cooling tower is used in conjunction with a chiller. Water-cooled chillers are normally more energy efficient than air cooled chillers due to heat rejection to tower water at or near wet-bulb temperatures. Air cooled chillers must reject heat at the dry-bulb temperature and thus have a lower average reverse—Carnot cycle effectiveness. Large office buildings, hospitals and schools typically use one or more cooling towers as part of their air conditioning system. HVAC&#39;s use of a cooling tower pairs a cooling tower with a water-cooled chiller or water-cooled condenser. 
         [0004]    Industrial cooling towers are generally used to remove heat from various sources such as machinery or heated process material. A primary use of large industrial cooling towers is to remove the heat absorbed in circulating cooling water systems such that are used in many different types of plants including power plants, petroleum refineries, etc. A cooling tower serves to dissipate heat into the atmosphere instead of using circulating water which is discharged. Discharging large amounts of hot water can raise the temperature of a receiving river or lake to a non acceptable level for the local ecosystem. 
       SUMMARY OF THE INVENTION 
       [0005]    One of the problems associated with cooling towers is the build up of scale. If not properly treated, the scale will impede the flow of water and eventually completely seal the pipes. In order to prevent the above, there are two methods which can be utilized. The first method is the use of chemicals. The problem with such chemical use is the relatively high cost associated therewith as well as disposal of the blow down liquid. This is the portion of the circulating water flow that is removed in order to maintain the amount of dissolved solids and other impurities at an acceptable level. Typically, about 0.4% goes to the sewer. For a 500 ton chiller, this can be equal to approximately 9,000 gallons per day. 
         [0006]    A further or potential problem with cooling towers is legionnaire&#39;s disease. Common sources of legionella include cooling towers, domestic hot water systems, fountains and similar disseminators. It has been found that legionella can spread through the air up to 6 km from a large contained cooling tower. 
       SUMMARY OF THE INVENTION 
       [0007]    It is an object of the present invention to provide a system for the treatment of water in a cooling tower. 
         [0008]    It is a further object of the present invention to provide a method for the treatment of water in a cooling tower including a method for the disposal of the blow down liquid. 
         [0009]    According to one aspect of the present invention there is provided a method for the treatment of water used in a cooling tower, the method comprising the steps of drawing a portion of the water from a basin of the cooling tower, passing the portion of the water through a magnetic treatment device wherein the water and flux lines from the magnetic treatment device intersect at an angle and withdrawing blow down water and using said blow down water for irrigation. 
         [0010]    The magnetic treatment means are utilized to generate magnetic lines of flux through which the water passes. The preferred arrangement is that shown in U.S. Pat. No. 5,149,438 (the teachings of which are hereby incorporated by reference) wherein water is directed in a spiral manner such that it is subject to magnetic lines of flux at an angle. The device can be used to control and even remove scale previously formed. 
         [0011]    As is known in the art, periodically the cooling towers must be blown down with a portion of the liquid known as the blow down liquid being dumped to the sewer system. 
         [0012]    In the present invention, the water from the blow down is utilized for irrigation and avoids dumping to the sewer system. The blow down water usually has a relatively high concentration of calcium which has been found beneficial in the growing of healthy plants and fruit bearing plants. Calcium plays a role in the fertility of the soil by reducing its acidity. The blow down water used for irrigation is preferably used in close proximity to the cooling towers. In many operations, greenery is growing nearby and can range from roof top greenery to greenery or shrubbery on the ground. Naturally, the irrigation water could also be stored in a container and pumped or transported to other sites for irrigation. 
         [0013]    When the water in the cooling tower is subjected to a magnetic catalytic treatment as in the present invention, the blown off liquid is typically less than 100%. The blow off liquid is concentrated with minerals such as calcium, magnesium and iron which are suitable for use as nutrients for grass and plants. A 400 ton cooling tower normally circulates at approximately 1200 GPM with the bleed off or blow down being 4.8 GPM which is equal to approximately 6,900 gallons of water per day. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    Having thus generally described the invention, reference will be made to the accompanying drawings illustrating an embodiment thereof, in which: 
           [0015]      FIG. 1  is a perspective view of a structure and associated cooling tower; and 
           [0016]      FIG. 2  is a schematic view illustrating operation of the system. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]    Referring to the drawings in greater detail and by reference characters thereto, there is illustrated a building  10  which has a cooling tower  12  associated therewith. It will be understood that cooling tower  12  may be utilized in conjunction with other than building  10  including, for example, industrial cooling towers such as utilized with power plants, petroleum refineries, etc. 
         [0018]    Cooling tower  12  and the associated system are illustrated in greater detail in  FIG. 2  and reference will now be had thereto. Cooling tower  12  has a central portion  80  and a basin  82  associated therewith. This is a conventional structure in the art. A recirculating loop  84  has a condenser  86  associated therewith. 
         [0019]    The magnetic treatment system of the present invention is generally designated by reference numeral  14  and includes an inlet conduit  16  extending from basin  82  for removing a portion of the liquid therefrom. Inlet conduit  16  feeds the liquid to a pump  18  wherein the liquid is pumped through a conduit  19 . A purge valve  20  is mounted on conduit  19 . A further valve  21  is mounted between purge valve  20  and a centrifuge  22 . Centrifuge  22  includes a purge valve  24  located at the bottom thereof and which can be used to discharge material to sewer  25 . The liquid is fed from centrifuge  22  through conduit  26  on which there is mounted a conductivity probe  28 . Conduit  26  feeds the fluid to catalysers  30 ,  32  each having a valve  34 ,  36  respectively at the outlet thereof. Subsequently, the liquid goes to an outlet  38  where it is fed back into basin  82 . 
         [0020]    A bypass conduit  39  has a valve  40  mounted thereon intermediate a first manometer  42  and a second manometer  44 . 
         [0021]    The system preferably includes a biocide-algicide injector  46  and pumps  47  for bacterial and algicide growth control. 
         [0022]    The system will include suitable controls including a conductivity control  48 , a purge control  50  and a pump control  52 . 
         [0023]    A make-up line  56  is provided to feed additional water as required. Mounted on make-up line  56  is a further catalyser  58 . 
         [0024]    There is also provided a further catalyser  62  which is mounted in association with recirculating loop  84  to withdraw a small amount of water therefrom and subject the same to the catalytic treatment. 
         [0025]    Purge valve  20  has a conduit  66  associated therewith for feeding the liquid to a tank or storage device  68 . From there, the liquid may be used for irrigating greenery  70 . 
         [0026]    The greenery  70  may be located at any desired location including, for example, on the roof of building  10 . Alternatively, the irrigation water may be transported to other locations for use. 
         [0027]    Each of the catalysers  30 ,  32 ,  58  and  62  subject the water to a magnetic treatment which is preferably of the type taught in U.S. Pat. No. 5,149,438, the teachings of which are hereby incorporated by reference. 
         [0028]    The catalysers  30 ,  32 , 58 ,  62  are designed to treat approximately 10% of the flow of the water from the basin to the cooling tower. Naturally, this may be varied, but this amount has been found to provide for an effective treatment. 
         [0029]    It will be understood that the above described embodiment is for purposes of illustration only and that changes and modifications may be made thereto without departing from the spirit and scope of the invention.