Abstract:
A solid chemical feed unit dissolver has an upper feed unit chamber with an inwardly tapering sealing surface at its lower end and against which a lowermost feed unit seals, retaining the upper chamber in a dry condition, preventing wetting and caking of solid chemical feed units behind the dissolving and sealed off face of the solid chemical feed unit. A solid chemical feed unit magazine is slotted to permit gentle feeding of a plurality of solid chemical feed units therein and a cover-defined sight slot permits guiding and visual observation of remaining solid chemical feed units in the magazine. The magazine preferably, but not necessarily, defines the tapering sealing surface. Distinctly shaped solid chemical feed units are disclosed. The dissolver can handle large solid chemical feed unit loads up to one hundred pounds or more and in a small footprint stable configuration. Methods are disclosed.

Description:
PRIORITY CLAIM 
     Benefit of the filing date, Mar. 8, 2010 of provisional patent application Ser. No. 61/339,702 entitled SOLID CHEMICAL DISSOLVER AND METHODS is claimed, and that application, in its entirety, is expressly incorporated herein as if fully set out herein. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to apparatus and methods for dissolving chemicals from a solid form to produce a chemical solution. More particularly, this invention relates to chemical dissolvers and methods for producing chemical solutions for water or process treatment from solid form chemicals. 
     BACKGROUND OF THE INVENTION 
     It is known to provide concentrated chemical solution for introduction into liquid systems or processes for a variety of purposes. For example, chemical concentrates, including mixtures of different chemistries, are diluted to provide solutions for water treatment and prevention of scale and deposit accretion and buildup in tanks, boilers and cooling towers and in both open and closed water systems, for industrial cleaning, for detergent production in dishwashing systems and washing machines, for other cleaning and sanitizing purposes, and for continual and periodic cleaning and maintenance functions in a variety of applications. 
     Typically, a “dissolver” for dissolving or diluting a chemical is used to receive a chemical concentrate, dissolve or dilute it, and introduce the resulting solution to a system for treatment. 
     Specific disclosures of such prior apparatus and processes are found, for example, in U.S. Pat. Nos. 2,371,720; 3,383,178; 3,595,438; 4,858,449; 4,964,185; 5,137,694; 6,441,073; 6,418,958; 6,820,661; in United States Patent Publication Nos. US2007/0269894 and US2010/0025338. Each of these is expressly incorporated herein by reference and is a part hereof as if fully set out herein. Copies of these are attached and are a part hereof. 
     Moreover, it will be appreciated that systems for producing a concentrated chemical solution and for delivering that solution to a system for use are typically designed for specific applications due to the parameters of the system to be treated; all the way from washing machines on one hand to closed loop water tower and processes or building cooling systems on the other. Volumes, pressures, temperatures, water chemistries, chemical solutions required and many other parameters require significantly different dissolving and delivery systems. 
     Another consideration in this field is the state or form of the concentrated chemical used to form the treatment solution. Concentrated chemicals can be provided in either a concentrated liquid form or in a “solid” form. The term “solid” is herein used to differentiate or distinguish from other forms of chemical such as granules, flakes, beads, free flowing aggregates, particulates, powder and liquid. The terms “solid” and “solid chemical feed unit” as used herein are thus intended to refer to a monolithic mass in a freestanding, structural shape which may be formed by any suitable process including but not limited to compression, casting, molding and other processes. When dissolving a chemical in solid form, it is typical to spray a pattern of water onto the face of the solid chemical. 
     Comparisons of liquid to solid concentrated chemicals are set out in United States Patent Pub No. US2010/0025338, incorporated herein by reference. 
     When considering use of chemicals in solid form such as solid chemical feed units, particularly in the treatment of larger water systems such as heating and cooling systems, relatively larger amounts of concentrated chemical are required as compared to smaller volume systems. Regardless of the size of the solid chemical feed unit system, the feeding and dissolving process must be consistent so the chemical solution produced by the dissolving process is accurate and consistent. 
     Potentially interfering with these considerations is the nature of the interface of the solid chemical feed unit being dissolved by a water spray. While it is important to consistently dissolve chemical from the solid feed unit at a forward surface of that unit, it is also desirable to maintain chemical behind that surface as dry as possible to prevent such wetting and caking as would prevent consistent presentation of chemical at a location where the water spray most effectively and uniformly dissolves the chemical. Said in another way, if chemical in a solid feed unit behind the interface of the forward surface and the water spray becomes wet or cakes, feeding or movement of the solid chemical feed unit toward the spray interface can be adversely affected, as well as the surface of the solid chemical receiving the spray pattern. This can result in stoppages, in inconsistent solution production and in production of widely varying solution content adversely affecting the efficiency and viability of the treatment desired. 
     In another aspect of solid chemical feed unit dissolving, it is desirable that operator time and attendance at the dissolver be reduced, even while the dissolver must be capable of producing large amounts of chemical solution for large volume applications. This requires operable disposition of significant numbers of solid chemical feed units in the dissolver. While a plurality of such solid chemical feed units might be stacked, such as a small plurality of such solid chemical feed units in a much lower capacity dissolver (like four solid chemical feed units provided in a gallon-sized bucket), it is desired to provide apparatus and processes for handling much larger amounts of solid chemical feed units for much larger applications without the frequent operator attention required for gallon-sized solid chemical feed unit fills in such larger units. 
     It is also desirable to provide solid chemical feed unit dissolvers facilitating use of multiple solid chemical feed units without damage from dropping solid chemical feed units one onto another, and without feeding or consistency issues arising from wetting or caking. For example, in some applications, it may be desirable to accommodate fills of about fifty to two hundred pounds or so of total solid chemical feed unit weight where large volume systems are to be serviced. And it is desired to do so within a small dissolver footprint, but in a stable application. 
     Finally, it is desirable to provide the capability of observing the feed units in the dissolver as an indication of current status and the need to replenish the feed units for consistent treatment. Typical small capacity dissolvers do not provide such observation capacity. 
     SUMMARY OF THE INVENTION 
     To these ends, the invention contemplates an improved solid chemical feed unit dissolver and solid chemical feed units combined to facilitate multiple solid chemical feed unit filling, provide high capacity dissolver operation, prevent undesirable feed unit caking and wetting, provide visual feed unit status and provide consistent sustainable chemical dissolving and solution for system treatment, all in a small footprint and from a stable dissolver. 
     A preferred embodiment of the invention contemplates a magazine sized and shaped to handle, preferably, a plurality of solid chemical feed units, in one form comprising disc-shaped feed units stacked vertically in the upper chamber of the magazine. A tapered sealing surface, smaller in diameter than the lower face of a disc-shaped feed unit, is preferably an integral part of the lower end of the magazine. The periphery of the lowermost feed unit rests on this surface, sealing the upstream chamber of the magazine from a spray directed upwardly through a screen and against the lower face of the lowermost feed unit to dissolve the solid chemical into a solution flowing downwardly and collected in a reservoir. 
     As the lower face of the feed unit is dissolved, the feed init progressively feeds, downwardly toward the plane defined by the lower dissolving face thereof and its seal contact with the tapered surface. 
     Thus, as the solid chemical is dissolved by the spray at this lower face, that feed unit, and those above, move progressively downwardly, yet the upper chamber above the plane where the dissolving action occurs is sealed by the advancing chemical feed unit so the upper chamber and feed units therein are retained in a relatively drier area and do not mat, clog or otherwise adversely affect the accurate and consistent dissolving of the chemical at the lower face of the lowermost feed unit. 
     The magazine is provided with access slots to facilitate gentle handling of the feed units which are loaded into the magazine, and with visual access therein to permit an operator to determine the load status of the magazine. 
     These and other advantages and modifications of the invention will become readily apparent from the following written description and from the drawings in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an illustrative cross-sectional view showing a dissolver with feed unit magazine mounted thereon and showing the lower end of the magazine where the inwardly tapering surface forms a seal with the lower edge of the lowermost solid chemical feed unit; 
         FIG. 2  is an isometric view of a dissolver and magazine as in  FIG. 1  wherein selected components are shown in transparent format for clarity and explanation; 
         FIG. 3  is a perspective view of a dissolver and magazine of  FIG. 1 , illustrating an uncovered magazine, filled with solid chemical feed units; 
         FIG. 4  is an elevational view of the dissolver and covered magazine of  FIG. 1 , with solid chemical feed units visible through a magazine slot and cover sight window; 
         FIG. 5  is a top plan view of a dissolver and magazine; and 
         FIG. 6  is a schematic flowchart showing flow of regulated water from the regulator to the serially connected second and first valves to the spray nozzle, and also illustrating diagrammatically the overflow tank and the solution reservoir (depicted in two places), as well as the solid chemical feed unit, tapered sealing surface and screen. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Preferably as used herein, the term “dissolver” includes a solid chemical feed unit dissolving apparatus and an associated operatively mounted solid chemical feed unit magazine or guide for holding and introducing successive solid chemical feed units sequentially to a dissolving location or station in the dissolver. 
     As illustrated in the drawings, preferred solid chemical feed units useful in the invention are in the form of a cylinder or disc  10  having a forward face  12  defined by a circular edge  14 . Disc  10  has predetermined height and is preferably, but not necessarily, from six to nine inches in diameter, about one to six inches in height and preferably three inches high. Preferably, the forward face  12  is about 20 inches to 110 square inches in surface area. Preferably, a single solid chemical feed unit weighs in the range of eight to ten pounds. These parameters are illustrative only; other sizes, areas and weights could be used. 
     One embodiment of the invention comprises a unique solid chemical feed unit magazine  16  in operable cooperation as part of a dissolver apparatus  18  wherein the magazine  16  has a slight inwardly tapered surface or constriction  20  at a lower magazine end  22 , just upstream or above a first screen  24 . As noted, a solid chemical feed unit  10  is preferably, but not exclusively, cylindrical in shape, with a lower circular face surface  12  defined by an edge  14  engaging the tapered surface  20  of the magazine  16  and sealing off upper chamber areas  26  of the magazine above the seal  28  produced by the engagement of the lower feed unit edge  14  with the tapered surface  20 . 
     Alternately, the tapered surface  20  may be operatively disposed in the dissolver  18  at a seal location downstream of the magazine  16 , while providing a seal against moisture intrusion into the magazine  16  and above the face surface  12  of a feed unit  10  being dissolved. 
     The upper first screen  24  is disposed in the magazine  16  proximate the so-formed seal  28  and just below the lower face  12  of the forward or lowermost solid chemical feed unit  10 . The first screen  24  is of any suitable construction and preferably of stainless steel wire in No. 2 mesh, i.e. one-half inch mesh. An upwardly directed nozzle  30  is disposed below the screen  24 . The nozzle  30  sprays a consistent and preferably uniform water pattern up through the screen onto the lower circular face  12  of the solid chemical feed unit  10 , which is thus dissolved. As the solid chemical feed unit  10  is so dissolved, dissolved chemical drops toward and through the first screen  24  onto a collection funnel  32  or tapered collecting surface thereof, yet all the while its advancing lower face  12  at its circular edge  14  seals against the tapered surface  20 , preventing wetting and caking of the solid chemical feed unit or units  10  above the dissolving face  12 . The solid chemical feed unit  10  and successive solid chemical feed units descend in the magazine  16  toward the tapered surface  20  and seal as the nozzle  30  continues to spray, maintaining both the seal  28  and the presentation of a feed unit surface for dissolving by the nozzle  30  spray. The seal  28  is maintained whether the nozzle spray  30  produces continuously or intermittently. 
     As the face  12  of the solid chemical feed unit  10  is sprayed and dissolved by the water, diluted chemical solution falls past the nozzle onto a secondary, lower screen  34  at the bottom of funnel  32  for catching any lumps or pieces of undissolved chemicals falling through the first screen  24  and which are collected and optionally presented to waste. The lower screen  34  is preferably an integral part or floor of the collection funnel  32  with a plurality of one-quarter inch holes therein, whereby pieces of undissolved chemical are captured in the floor and can be further dissolved. 
     Thus, it will be appreciated that the magazine  16  defines an upper feed unit chamber  26  for accepting a plurality of solid chemical feed units  10  in tandem and for feeding each unit  10  serially toward the tapering surface  20 , forming a seal  28  with the edge  14  of the lowermost feed unit. 
     In another aspect of the invention, the magazine  16  defines two elongated slots  36 ,  38  ( FIG. 3 ) on opposite sides thereof. Cylindrically-shaped solid chemical feed units  10  are manually lowered within the magazine  16  and from the top by physical support facilitated by the slots  36 ,  38 , until the feed units  10  are settled on the seal  28  or on the proceeding feed unit  10 . A guide cover  40  is placed on the last or uppermost feed unit  10  and follows the units  10  downwardly as they are successively dissolved. If the last unit in the magazine is fully dissolved, the guide cover  40  deflects any spray from the nozzle  30  from entering the magazine chamber  26  through the screen; it too sealing or contacting the tapering seal surface  20 . 
     A magazine cover  42  may be disposed over the magazine  16 . This cover  42  is preferably provided with an elongated sight window  44  with measuring scale aligned with one of said slots  36 ,  38  and through which the feed units  10  therein can be viewed and measured as an indication of solid chemical feed unit status and any need to load more solid chemical feed units  10 . It is thus easy for an operator to assure continued operation of a treatment process by visual observation. 
     Just below the tapered surface  20  of the magazine,  16  a circular groove  46  in a surface of either the magazine  16  or other dissolver parts accommodates, supports or positions the periphery of the circular screen  24  noted above. The further tapered surface below the screen in the form of a collection funnel  32  funnels chemical solution downwardly to a collection area or reservoir  48  within the dissolver  18  wherein one or more floats  50 ,  52  are disposed to control water flow through line  55  to the nozzle  30  based on the fill condition of a solution reservoir  48 . Primary chemical solution is directed to a solution reservoir  48  in which a float  52  activates a first valve  54  when the reservoir  48  is filled, shutting off water to the nozzle  30 . If that reservoir  48  has overflowed into an overflow tank  56  despite the condition of the first valve  54  and its float  52 , a second float  50  in the overflow tank  56  shuts a second valve  58 , serially connected to the first valve  54  (through conduit  57 ) from upstream thereof, as a failsafe to shut off water from water inlet  59 , pressure regulator  59   a  and conduit  61 , to the first valve  54 , line  55  and nozzle  30  and to stop nozzle  30  spray onto a feed unit  10 . The supply of water to the serially-connected valves  54 ,  58  and nozzle  30  is pressure regulated to produce a consistent spray from the nozzle  30 . 
     A pick-up tube  60  transfers chemical solution to an outlet pump  62  from the solution reservoir  58  for transport to a water system or other process stream. 
     Also, it will be appreciated that the invention is useful in multiple applications where available water pressures might vary significantly from one application to the other and in the approximate range of 25 to 100 psi and more likely 25-40 psi. According to the invention, the water supply nozzle  30  is regulated to about 25 psi (regulator  59   a ) and at this pressure, the nozzle  30  delivers water diluent in a spray pattern to the face of the solid chemical feed unit at a rate of about 0.5 gallons per minute to produce a chemical solution at about 0.5% to about 1.0% concentration. 
     Preferably, and to provide consistent chemical solution by presenting a continually uniform solid chemical feed unit face  12  and surface area defined at the forward face, each solid chemical feed unit  10  has a shape such that surface area of the solid chemical feed unit is positioned at a constant distance from the nozzle  30  at the first screen  24 . Provision of a uniform water pattern, emanating from a nozzle  30  at a uniform distance from the face of the operative solid chemical feed unit, and at a uniform low pressure facilitates a consistent, accurate and constant solution and treatment process. 
     It will also be appreciated that the dissolver  18  provides a very high capacity solid chemical feed unit dissolving process but in a relatively small footprint. Essentially, the dissolver unit  18  at its lower end is about 24 inches wide by 28 inches long and about one foot tall, or alternately, it could be other sizes, such as 18 inches wide and about 22 inches long. The housing  66  forms preferably integral both reservoir  48  and overflow tanks  56  of about one quart capacity each, and an additional containment tank  68  beyond these two tanks to accommodate an unexpected spill or malfunction. The magazine has an upper loading end  70 , about five feet from the bottom of the dissolver housing  66 , and is about thirteen inches in diameter, with cover  42 . The lower end of the magazine is secured to the dissolver housing  66  so it does not separate if the entire apparatus is tipped. Since the lower end of the magazine  16  is disposed within the housing  66 , the center of gravity of the unity is relatively low and the dissolver is stable. For example, magazine  16  may be supported by an integral seat  72  of housing  66 , and other portions of the housing  66  and may be otherwise suitably fastened to the housing. 
     It will thus be appreciated that the dissolver  18  is partially defined by a housing  66  or body which usefully comprises a molded housing  66  of any suitable material defining a solution reservoir  48 , an overflow tank  56 , a containment tank  68 , a seat  72  for a magazine and such conduits, valves  54 ,  58  nozzle  30  and the like to perform the dissolving function. The reservoir  48  and overflow tank  56  may be an integrally formed portion of the dissolver body  66 . As will be appreciated, the magazine  16  is removably but securely seated on the dissolver  18  as shown in the drawings. The tapered sealing surface  20  and screen  24  could be formed in the dissolver  18 , below a magazine  16 , if desired, as opposed to the preferred disposition as part of the magazine  16 . 
     In an alternate embodiment, the solid chemical feed units  10  may be provided in other shapes than cylinders or discs. For example, a disc shape with a sector removed, a unit in the form of a multiple-sided shape of curved or straight lines, or a variety of other feed unit shapes could be used. Consequently, the tapering seal surface  20  may also be provided in similar and cooperating configurations to produce the seal  28  with the solid chemical feed unit  10  discussed herein and to prevent moisture transport or migration beyond a spray-receiving dissolving face  12  of such a feed unit. 
     The parameters of a uniform pattern consistent with the shape of the solid chemical feed unit face  12 , uniform distance from spray nozzle  30  to that face, and uniform water pressure are all preferably provided and retained. 
     These embodiments facilitate treatment of a variety of process streams from solid chemical feed units. 
     From the foregoing, it will be appreciated that the invention provides a solid form chemical dissolver having a unique high capacity magazine and solid chemical feed units and which prevents dissolving process obstruction from wetting or caking of subsequent solid chemical feed units as well as provides consistent chemical dissolving, either continuously or intermittently, and resulting accurate solutions for system treatments. These benefits are attained in addition to such improved apparatus and methods as a result from a dissolver of small footprint, providing high capacity in a yet stable unit with accurate solution production and decreased operator time and attention. 
     A variety of solid chemicals provided in solid chemical feed units can be used with this invention. These include, by way of example only, and without limitation: phosphonate; tolytriazole; molybdate; polymers; caustics; sulfite and nitrate. 
     These and other advantages and modifications will become readily apparent to those of ordinary skill in the art and without departing from the scope of this invention and applicant intends to be bound only by the claims appended hereto.