Abstract:
An apparatus and method for removing water and debris from a cooling tower basin, discarding debris and returning clean water to the basin.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention is directed to cooling towers and particularly to an apparatus and method for removing water and debris from a cooling tower basin, discarding debris and returning clean water to the basin.  
         [0002]     Cooling towers are a component of commercial and industrial heat transfer equipment including for example chillers, coolers, and air conditioning systems. A cooling tower transfers heat from such equipment to ambiance. In a cooling tower, heat is removed from recirculating cooling water by cascading the water over baffles and by drawing a countercurrent of ambient air through the baffles so as to cool the cascading water. Air so heated is exhausted to atmosphere and the cooled recirculating water is collected in a basin situated in the tower under the baffles. The cooling tower basin being exposed to the atmosphere accumulates sediment including airborne dirt, dust, organic matter and so forth that contaminates the water and consequently fouls heat exchange tubes in a heat transfer system.  
         [0003]     There are systems for cleaning cooling tower basins such as U.S. Pat. No. 4,839,064 directed to the use of an installation of a siphon and filter together with a portable tool for cleaning one or multiple basins, or a permanent installation including a basin tool for one or more towers. According to the patent disclosure, water and debris are siphoned from a cooling tower and discharged to sewer through a filter. In a modified apparatus for an above-grade siphon, a pump within a hermetically sealed receiver establishes and maintains a siphon from basin through a filter to discharge. For operation of the modified apparatus of the patent, the system is primed between basin and receiver, and the pump is operated to draw water and sediment from the basin for discharge through a filter. The &#39;064 patent requires a permanent installation of components such as receiver and pump unit, or is limited to slow and uncertain action of continuous siphon action for cleaning a basin.  
         [0004]     U.S. Pat. No. 4,306,967 discloses a trailer mounted cleaning apparatus for cleaning cooling tower water including a diesel engine driven pump, a filter device, a bank of hydrocyclone separators, and a sediment collecting tank. Clarified effluent from a cooling tower basin is recirculated back to the cooling tower basin, and sediment is collected in the tank for later removal by means of an auger fitted into the tank.  
         [0005]     There is need for a conveniently deployed and operationally efficient method and apparatus for cleaning cooling tower basins.  
         [0006]     The present invention is directed to an apparatus and method for removing contaminating debris from cooling tower basins.  
       SUMMARY OF THE INVENTION  
       [0007]     In accordance with the present invention, a cooling tower recirculating water cleaning apparatus comprises an integrated portable machine including a mounting carriage, a debris collecting tool, a strainer, a motor driven self-priming centrifugal pump, and a discharge line to drain. The apparatus cleans the cooling tower basin by placing the debris collecting tool into the basin, priming the pump, and operating the pump to withdraw water and debris from the basin, straining the water and debris upstream of the pump, and discharging water and entrained debris to a sewer. In preparation for cleaning the basin, make-up water is added to the basin to allow for removal of approximately 20-25% of basin water in a cleaning operation. Thereafter, the basin debris is undisturbed allowing it to settle to the bottom of the basin for 24-48 hours before cleaning. For actual cleaning the collecting tool is placed in the basin water to collect and remove debris as the centrifugal pump removes and discards debris laden water.  
         [0008]     In a modified embodiment of the apparatus of the invention, water and debris drawn from a cooling tower basin is filtered during a cleaning operation, and filtered water is returned to the basin.  
         [0009]     Specific examples are included in the following description for purposes of clarity, but various details can be changed within the scope of the present invention.  
       OBJECTS OF THE INVENTION  
       [0010]     An object of the invention is to provide an apparatus and method for removing sediment and debris from a cooling tower basin.  
         [0011]     Another object of the invention is to provide a mobile apparatus for quickly, conveniently and routinely cleaning cooling tower water of sediment and debris so that recirculating cooling tower water is maintained in a clean condition thereby avoiding fouling heat exchanger tubes.  
         [0012]     Another object of the invention is to provide apparatus for quickly, conveniently and routinely cleaning a cooling tower water basin of sediment and debris and returning filtered water to the basin.  
         [0013]     Other and further objects of the invention will become apparent with an understanding of the following detailed description of the invention or upon employment of the invention in practice. 
     
    
       [0014]     A preferred embodiment of the invention has been chosen for detailed description to enable those having ordinary skill in the art to which the invention appertains to readily understand how to construct and use the invention and is shown in the accompanying drawing in which:  
         [0015]      FIG. 1  is perspective view of an apparatus for cleaning cooling tower water according to the invention.  
         [0016]      FIG. 2  is a side elevation view of interior components of the apparatus of  FIG. 1 .  
         [0017]      FIG. 3  is a view of the apparatus in position for cleaning a cooling tower in practice of the invention.  
         [0018]      FIG. 4  is a perspective view of a tool for engaging and vacuum gathering water and sediment in a cooling tower basin. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0019]     Referring to the drawing, the apparatus  10  for cleaning cooling tower water according to the invention comprises a carriage  12  having a supporting base  12   a  fabricated of robust material such as steel or aluminum for mounting the operating components of the apparatus, a set of wheels  14  affixed to one end  12   b  of the base for wheeling the apparatus into position beside a cooling tower, an extensible handle  16  projecting from the other end  12   d  of the base, and a stand  18  depending from the other end of the base for level positioning of the apparatus for cleaning a cooling tower basin and recirculating water.  
         [0020]     The apparatus further includes an outer housing  20  mounted along the perimeter of the base in covering relation to the operating components and comprising upstanding front  20   a , rear  20   b , left  20   c  and right  20   d  side walls, and a top cover wall  20   e  in three sections of upper  20   f , vertical  20   g , and lower  20   h  top wall portions. The left and right side walls include lower vertical  20   i  and upper inclined  20   j  sections. The outer housing is formed of robust material such as stainless steel or aluminum, and has ventilation slots or louvers  20   k  for admitting ambient cooling air to the interior operating components of the apparatus.  
         [0021]     As shown in  FIG. 2 , the operating components of the apparatus assembled on the mounting carriage base  12   a  comprise a strainer  22  within a strainer housing  24 , a drive motor  26 , a centrifugal pump  28 , and a discharge line  30  to drain.  
         [0022]     The mounting base  12   a  is a robust aluminum plate with planar surface of sufficient strength to carry the operating components and to withstand torsion and other forces generated in operation of the apparatus. A pair of semi-pneumatic supporting wheels  14  connected by an axle  14   a  support one end  12   b  of the base and provide for close positioning of the apparatus at a cooling tower basin ( FIG. 3 ) enabling an operator to manipulate vacuum hoses and tools as desired for cleaning the basin.  
         [0023]     An electric drive motor  26  is positioned at the one end of the mounting base between the wheels and is bolted to the base plate. A pump-mounting cage  27  is bolted to the front face  26   a  of the drive motor and the cage in turn receives centrifugal pump  28  bolted to the cage with the pump shaft  28   a  in axial alignment with and connected to the motor drive shaft  26   a . The result is integral mounting of motor and pump affixed to each other and with only the electric motor affixed to the mounting base. The electric motor is preferably one and one-half horsepower and either 115v or 230v with an on/off operating switch  26   b . The centrifugal pump is preferably of 60 gpm capacity with discharge overpressure of approximately 39 psi and an inlet underpressure of approximately 11 psi.  
         [0024]     The centrifugal pump  28  includes an axial inlet manifold  28   b  and a tangential outlet manifold  28   c  for drawing fluid to the inlet at a negative 11 psi and discharging at positive 39 psi at the outlet.  
         [0025]     A lightweight strainer housing  24  has an integral outlet connection  24   d  that is affixed to and supported in operating position by the pump inlet manifold  28   d . The strainer housing is preferably fabricated of molded plastic with imperforate outer wall  24   a  projecting through an opening  12   e  in the mounting base, a fluid inlet connection  24   b , an outlet connection  24   d , an interior chamber  24   e  for receiving a perforated fluid strainer, and a removable top cover  24   f  for periodically removing and cleaning the strainer. Interior baffles (not shown) in the strainer housing direct inlet water through the strainer before entering the pump inlet manifold. The strainer  22  is preferably fabricated of aluminum with three-sixteenth inch perforations.  
         [0026]     A discharge pipe  30  is connected to the pump discharge manifold  28   c  and extends underneath the upper top wall  20   f  through the rear housing wall  20   b  and terminates in a discharge connection  30   a  which receives a drain hose  31  ( FIG. 3 ). A discharge valve  32  is fitted to the discharge pipe with valve stem  32   a  extending through the upper wall  20   f  and a stop valve handle  32   b  accessible outside the upper wall. The front end  30   b  of the discharge pipe is fitted with a priming water hose connection  34  and priming water valve  36  for regulating water flow through this connection. As more fully described below, a water hose  38  connected to the discharge pipe with closed discharge valve and open priming valve provides for initial priming of the centrifugal pump prior to cleaning a tower basin.  
         [0027]     It is to be understood that the apparatus of the present invention especially as seen in  FIG. 2  comprises a robust, compact maneuverable assembly in which an integral unit comprising motor, pump, strainer housing, and discharge pipe are affixed to each other with only the motor housing affixed to the mounting base, and with heavy components including drive motor, mounting cage, centrifugal pump and discharge pipe positioned from midpoint  12   c  to the one end  12   b  of the mounting base ensuring that the wheeled end of the unit bears a major portion of unit weight both at rest and while in motion. The entire apparatus weighs on the order of one hundred twenty-five pounds and is provided with a handle  16  that is extended ( FIG. 2 ) for added leverage in tilting the carriage to “wheel around” position and retracted ( FIG. 3 ) for compact storage when the unit is stationed at a cooling tower for cleaning operations.  
         [0028]     As shown in  FIG. 4 , the apparatus includes a basin tool  40  through which water and sediment are drawn by the centrifugal pump. The tool is fitted to the far end  42   a  ( FIG. 4 ) of an inlet hose  42  that extends from the basin B for connection at its near end  42   b  to the strainer housing inlet  24   b  ( FIG. 3 ). The inlet hose is provided with an inlet control valve  44  allowing an operator to open and close the inlet hose as desired during a cleaning operation.  
         [0029]     The tool  40  is a hollow shell with a tubular portion  40   a  for connection to the inlet hose  42 , and an integral head  40   b  with walls in the general form of a prism. The tool head walls define a depending skirt  40   c  with a generally rectangular perimeter edge  40   d  having spaced rectangular notches  40   e  defining a plurality of portals for passage of water and sediment from a cooling tower basin into the tool head when the centrifugal pump is in operation pulling negative 11 psi through the tool.  
         [0030]     To prepare for cleaning a cooling tower basin, make-up water of about 20-25% of tower capacity is added to the system. The cooling tower is then shut down for a 24-hour period allowing sediment to settle in the cooling tower basin. The apparatus of the present invention is wheeled into position next to the basin with the tool head placed in the basin. The centrifugal pump is primed when the system is filled with water between the discharge valve and the tool head situated in the basin. Priming is accomplished by closing the discharge valve, opening the prime water inlet valve, connecting the inlet hose at its near end to strainer inlet with basin tool at the far end submerged in basin water, opening the inlet hose valve, and flooding the system between discharge valve and basin tool with tap water supplied through the prime water valve by a utility hose.  
         [0031]     For operating the unit to evacuate the basin and clean the cooling tower water, the motor switch is turned on to start pumping, the discharge valve is immediately opened and the prime valve is closed. Water and sediment pumped from a basin may be discharged to a sewer or may be filtered and clean water returned to the basin. When an operation is complete, the strainer is removed, cleaned and replaced and the unit flushed with clean water.  
         [0032]     In a modified form of the invention, a self-priming centrifugal pump may be used.  
         [0033]     Various changes may be made to the structure embodying the principles of the invention. The foregoing embodiments are set forth in an illustrative and not in a limiting sense. The scope of the invention is defined by the claims appended hereto.