Abstract:
A system for dissolving solid chemicals in an aqueous liquid, the system including a hopper that holds a plurality of stacked solid blocks containing water treatment chemicals for use in industrial and process applications, a liquid flow control system that delivers a selectively controlled flow of pressurized aqueous liquid to sprayer outlets that cause the pressurized liquid to impinge sequentially against the bottom surface of the bottom block in the stack, thereby successively dissolving each block, and a reservoir disposed beneath the stack that collects and holds the aqueous fluid containing the solubilized chemical from the blocks until it is discharged for subsequent use.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention relates to a system and apparatus useful for dissolving water treatment chemicals that are provided in the form of water-soluble, solid rectangular blocks or “bricks.” The chemical-containing blocks can be stacked in a hopper and are dissolved sequentially by controlled sprays of water that are directed against the bricks disposed in the stack. The sprayed water, containing dissolved chemicals, can be recaptured by gravity flow and accumulated in a reservoir disposed in the base. The liquid level in the reservoir is controlled as desired, and the chemical-containing water is subsequently discharged for use in various applications for industrial and process water treatment. 
         [0003]    2. Description of Related Art 
         [0004]    Various systems and devices have previously been disclosed for use in dissolving and dispersing chemicals in aqueous liquids. It is commonly known, for example, that 3-inch diameter tablets containing stabilized chlorine can be utilized in swimming pool chlorinators, either in addition to or in place of granular or powdered chlorine-containing chemicals, to eradicate bacteria and other harmful microorganisms. 
         [0005]    Similarly, other water treatment chemicals in solid form are presently used, for example, as scale or corrosion inhibitors, oxygen scavengers, pH adjustors, sludge conditioners, antifoamants, biocides, biodispersants, and the like, in industrial and process waters. Many such water treatment chemicals are specifically formulated for particular end use applications such as, for example, boilers, cooling towers, cooling water systems, wastewater and industrial effluents, and the like. Such chemicals have previously been provided as injectable liquids, as tablets or gels, or more recently, as 1-gallon bottles of solid concentrate. 
         [0006]    Considerations that can be important when evaluating possible sources and delivery systems for water treatment chemicals used for industrial and process water treatment include factors such as the storage space required for chemicals awaiting use, the frequency with which new chemicals are added to the system and the ease of such addition, the level of monitoring that is required during each operational cycle, whether a particular system can reliably produce aqueous solutions having a substantially constant solution strength throughout each operational cycle, whether the dissolution rate can be easily and reliably adjusted if desired; and whether the system apparatus is relatively inexpensive to manufacture, install and maintain. 
       SUMMARY OF THE INVENTION 
       [0007]    A preferred solid chemical dissolution system of the invention desirably includes a chemical containment apparatus and a liquid flow control system. The chemical containment apparatus includes a base with a liquid reservoir and a chemical hopper that slidably engages the base. A plurality of solid blocks, each desirably comprising at least one water treatment chemical suitable for the intended use, are stacked inside the chemical hopper, where they are supported by a grid disposed above the liquid reservoir. The liquid flow control system supplies a controlled flow of aqueous liquid to sprayers disposed beneath the hopper. The sprayers are directed through the openings in the grid and against the bottom of a stack of solid chemical-containing blocks disposed inside the hopper. A controlled flow of aqueous liquid is sprayed into contact with a facing solid surface having a substantially fixed rectangular shape, thereby producing a relatively constant concentration of solubilized chemicals for a given inlet flow rate. Because the chemical containment apparatus can include a plurality of blocks that are stacked one above the other inside the device, and because each block of chemical is significantly larger than conventional prior art tablets, the service intervals needed for chemical replacement can be significantly longer than would otherwise be experienced. 
         [0008]    The aqueous liquid that is sprayed against the bottom surface of the solid chemical block solubilizes a portion of the chemical(s) contained in the block and flows downwardly by gravity through the supporting grid and into the liquid reservoir of the chemical containment apparatus, where it is held pending discharge. The liquid reservoir desirably contains at least one liquid level sensor that is linked to a discharge valve that selectively controls a flow of aqueous liquid containing at least one solubilized chemical into another flow conduit to another process or system in which the chemically treated aqueous fluid is to be used. A discharge pump is optionally provided. 
         [0009]    According to one embodiment of the invention, the inlet valve, one or more level sensors, the discharge valve and/or, if provided, the optional discharge pump, are all electronically linked to a programmable controller with timing circuitry and indicator lights. The programmable controller is preferably powered by direct current and is attachable via a step-down transformer and inverter to a conventional AC power source. The inlet valve and, optionally, the discharge valve, can be solenoid actuated. If desired, a chemical analyzer can also be linked to the controller to input data regarding the pH or chemical concentration of the chemical-containing aqueous liquid. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The apparatus of the invention is further described and explained in relation to the following drawings wherein: 
           [0011]      FIG. 1  is a simplified exploded perspective view of a preferred embodiment of the chemical containment apparatus of the invention that includes without limitation a base unit, a hopper insertable into sliding engagement with the base unit, a support grid insertable into the hopper to support and maintain the chemical blocks, a plurality of chemical blocks, a cover, and an optional mounting bracket that can be used to secure the base unit to a wall or other support member; 
           [0012]      FIG. 2  is a perspective view of the apparatus of  FIG. 1 , minus the optional mounting bracket, after it has been assembled to form the chemical containment apparatus of the invention; 
           [0013]      FIG. 3  is a side elevation view of the chemical containment apparatus of the invention following installation of the liquid flow control system; 
           [0014]      FIG. 4  is an enlarged detail view of the liquid flow control system of the invention substantially as shown in  FIG. 3 ; 
           [0015]      FIG. 5  is a front elevation view of the solid chemical dissolution system of  FIG. 3 ; 
           [0016]      FIG. 6  is a rear elevation view of the solid chemical dissolution system of  FIG. 3 ; 
           [0017]      FIG. 7  is a cross-sectional plan view, partially broken away, taken along line  7 - 7  of  FIG. 5 ; and 
           [0018]      FIG. 8  is a cross-sectional elevation view taken along line  8 - 8  of  FIG. 3 . 
       
    
    
       [0019]    Like reference numerals are used to designate like parts in all figures of the drawings. 
       DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0020]    Referring to  FIG. 1 , a preferred embodiment of chemical dissolution system  10  of the invention includes a chemical containment system comprising base unit  12  with interior reservoir  26 , chemical hopper  14  comprising interior cavity  28 , a chemical block support grid  18  that is configured to rest inside interior cavity  28  on or near the top of support legs  72  of hopper  14 , and removable cover  20  that is configured to releasably close the top of hopper  14  after a plurality of substantially rectangular, solid blocks  16  comprising chemical solids are stacked inside hopper  14 . It should be understood that  FIG. 1  is not drawn to scale and that the thicknesses of individual solid blocks  16  are reduced as shown in order to fit  FIG. 1  on the page. A more accurate representation of the manner in which the stacked blocks  16  desirably fit inside hopper  14  is shown in  FIG. 8 , wherein it is seen that four stacked blocks substantially fill interior cavity  28  of hopper  14 . Base unit  12 , hopper  14  and cover  20  can be made of any suitable material but are preferably molded from a polymeric material that is resistant to degradation in the presence of whatever chemicals are present in blocks  16  or in the aqueous liquid that flows through system  10  during use. 
         [0021]    According to a preferred embodiment of the invention, the lower portion of hopper  14  is engageable, and most preferably slidably engageable, with interior reservoir  26  of base unit  12 . When the bottom of hopper  14  is inserted downwardly into reservoir  26 , the bottoms of legs  72  can rest on the bottom of base unit  12 . Because hopper  14  is preferably unitarily molded and legs  72  are hollow, a drain hole  74  is provided in each leg to allow aqueous liquid sprayed upwardly through grid  18  to flow back into reservoir  26  if it drains downwardly through the legs during spraying at discussed in greater detail below. A wall mounting bracket  22  is optionally provided for use in securing chemical dissolution system  10  to a wall or other vertical support using conventional fasteners  24 . As seen best in  FIGS. 4 and 6 , back side  78  of base unit  12  can comprise a mounting structure  32  having a tapered portion with tapered edges  82  and free end  34  that is spaced apart by gap  36  to permit free end  34  to be inserted downwardly into mounting bracket  22  so that tapered edges  82  are held by cooperative tapered sides of mounting bracket  22  ( FIG. 1 ).  FIG. 2  is a fully assembled view of the structures shown in  FIG. 1 , but with mounting bracket  22  omitted. It will be observed that when the lower portion of hopper  14  is seated inside base unit  12 , outwardly projecting bosses  70  on the outside wall of hopper  14  rest against the top edges of base unit  12  to further distribute the load that would otherwise be directed through legs  72  of hopper  14  to the bottom wall of base unit  12 . This can be more significant if, for example, base unit  12  is mounted to a wall rather than resting on an underlying support surface. 
         [0022]    Referring to  FIG. 3 , chemical dissolution system  10  preferably further comprises a liquid flow control system  30  not shown in  FIG. 1  or  2 , but which is further described in relation to  FIGS. 4-8  of the drawings. Referring first to  FIG. 4 , a preferred liquid flow control system  30  further comprises a liquid inlet  38  that is desirably connectable using conventional fittings to a source of pressurized aqueous liquid, most preferably a conduit supplying water at line pressure, although pressurized aqueous liquid can also be supplied using a pump (not shown) supplying liquid from a non-pressurized source, or by connecting inlet  38  to such other pressurized liquid source as may be available. Although it will be appreciated that the system and apparatus of the invention can be used, for example, to dissolve chemicals that are not water soluble in liquids that comprise solvents or the like in which such chemicals are soluble, a principal focus of the present invention is for use in solubilizing water soluble-chemicals into aqueous liquids. Pressure gauge  40  is provided for use in determining the pressure of the incoming liquid. If desired, a volumetric flow meter can also be provided in liquid inlet  38 , but in most cases, the flow rate of the aqueous liquid supplied to chemical dissolution system  10  will be determined by a solenoid  42  connected to an inlet valve disposed in liquid inlet  38 . Strainer  44  can be provided if desired for use in capturing sediments or solids that may be entrained in the inlet liquid. 
         [0023]    Programmable electronic controller  60  connected to a DC power supply by line  58  is desirably provided for use in controlling the flow of inlet liquid. The flow can be controlled in response to the sensed pressure and in response to data received from one or more liquid level sensors  52 ,  54  disposed in sump  50  that is in fluid communication with reservoir  26  inside base unit  12 . The use of both high and low liquid level sensors is preferred. An overflow drain  48  disposed just above the normal high liquid level position is provided for use where any component of system  10  fails with the inlet valve in an open position. Drain port  56  is provided for use in draining sump  50  and reservoir  26  if needed for cleanout. 
         [0024]    Referring next to  FIGS. 7 and 8 , during normal operation of chemical dissolution system  10 , a pressurized flow of aqueous liquid received through inlet  38  is delivered through conduit  46  to a manifold connected to the center bottom leg  72  of hopper  14 , where it is distributed to a plurality of laterally spaced sprayer outlets  84 ,  86  to produce an upwardly directed pressurized spray of aqueous liquid that passes through relatively wide openings in grid  18  and impinges against the major downwardly facing surface of the lowermost block  16  that is resting directly on the grid at that time. As the liquid sprays against the underside of the bottom block in the stack, chemicals disposed in the block are solubilized in the liquid, which then flows by gravity back down into reservoir  26 . During steady state operation, the liquid flow rate is maintained substantially constant, and liquid can be withdrawn from reservoir  26  through discharge valve  76  at substantially the same rate that liquid enters system  10  through inlet  38 . Level switches  52 ,  54  and solenoid  42  controlling the inlet valve can be used to compensate for minor irregularities in flow rate and pressure. 
         [0025]    As sprays  88  of aqueous liquid continue to impinge against the lowermost block  16 , it gradually erodes, and as it does so, the blocks above it drop down gravitationally to a position where the next sequential block in the stack is contacted by the liquid spray. With chemical dissolution system  10  operating in this manner, it is not necessary for system  10  to be serviced again until such time as the uppermost block in the stack, preferably the fourth block, is sufficiently eroded that it cannot provide a substantially constant surface area against which sprays  88  can impinge. At that time system  10  can be reloaded by removing cover  20  and placing four new blocks inside interior cavity  28  of hopper  14 . The additional space provided above the uppermost block in the stack permits four more complete blocks to be added without removing the block then being used in the bottom of hopper  14  and without risking letting the bottom block become so thin that it can fracture prior to refilling hopper  14 . 
         [0026]    Through use of chemical dissolution system  10  as disclosed herein, it is possible to provide longer service intervals and to provide a substantially constant rate of dissolution, thereby assuring a more constant concentration of chemical in the liquid that is collected in and discharged from base unit  12 . This is believed to be primarily attributable to a substantially constant spray pattern impinging against a substantially constant contact area at substantially constant pressure that is achieved through use of chemical dissolution system  10  of the invention. Where blocks  16  each comprise about 11 pounds of chemical, it has been determined that each group of four blocks comprises about the same amount of chemical as a 30-gallon drum. The blocks can be provided in an easily removable plastic wrap that is inexpensive and does not require direct contact with the skin of the user. 
         [0027]    Other alterations and modifications of the invention will likewise become apparent to those of ordinary skill in the art upon reading this specification in view of the accompanying drawings, and it is intended that the scope of the invention disclosed herein be limited only by the broadest interpretation of the appended claims to which the inventors are legally entitled.