Abstract:
A paint reclamation clarifier system in communication with a sump tank in a paint booth containing a carrier fluid for capturing paint droplets and a conduit for transporting the carrier fluid mixed with paint droplets to the reclamation clarifier system is presented. The clarifier system includes an influent port, a detackification agent inlet, a sludge tank in a lower portion of the clarifier for collecting the dispersed carrier liquid, where the paint droplets bond with the agent and settle to the bottom of the sludge tank, a sludge outlet, and, at least one effluent port located on or near an upper portion of a sidewall of the clarifier system permitting unsettled material to exit from the clarifier.

Description:
TECHNICAL FIELD 
       [0001]    This disclosure relates generally to a system and process for reclaiming paint overspray particles, and more particularly to a paint reclamation clarifier system and process for use. 
       BACKGROUND 
       [0002]    Spray painting either by a robot or human operator generates a large amount of overspray waste. Overspray paint byproduct or paint waste generated in paint spraying operations takes the form of either a liquid sludge or semi-cured product embedded on a filter media. The term “overspray” means those coating components that miss the target substrate during spray application of the coating and in the absence of particular precautions are lost. 
         [0003]    In the process of painting products, paint overspray and other chemicals are released into the atmosphere. If a paint booth is not properly maintained, it creates a health and safety hazard as well as an environmental hazard. There are two main methods for capturing these residual chemicals: dry filter scrubbers and water wash scrubbers. 
         [0004]    The dry filter method involves capturing the overspray in filters by pulling the soil-laden air through the filter. As the filter captures the paints it also becomes chemically laden, and then must be disposed of properly. The major trend has been a movement toward dry filter booths; however, this ultimately creates more waste with the addition of the filters now being a waste product. 
         [0005]    Water-wash paint booth systems capture oversprayed paint by using positive air pressure to force the particles into a cascading curtain of water. Various chemical and/or physical removal processes may be employed to remove the contaminants in the water. Theoretically, it is possible to recycle the water and the captured paint-by-product. 
         [0006]    The water-wash design, because of its high efficiency and wet byproduct characteristics, has faced substantial challenges with the promulgation of more restrictive landfill regulations. It is becoming increasingly prohibitive, both economically and environmentally, to dispose of paint waste byproducts because of these regulations. Therefore, it is desirable to avoid the problem of disposal by recovering and recycling the overspray paint waste produced into a high quality paint product. 
         [0007]    Paint is a tacky material and tends to coagulate and adhere to paint spray booth surfaces, particularly in sump and drain areas, and must constantly be removed from the sump to prevent clogging of the sump drain and recirculating system. In order to assist in the removal of the oversprayed paint from the air and to provide efficient operation of paint spray booths, detackifying agents are commonly employed in the water of such systems, and are typically incorporated into the water wash recirculated in the paint spray system. These agents may include, but are not limited to various fumed silicas. Detackifying the paint eliminates or minimizes the adhesive properties, or tackiness, of the paint, thereby preventing the oversprayed paint from adhering to the walls of the spray booth, etc. 
         [0008]    The use of hydrophobic fumed silica (HFS) as a paint detackifier is known. This technology is efficient in detackifying overspray paint in some currently designed booths. For example, one approach to recovering paint overspray particles is described in U.S. Pat. No. 5,092,928 issued Mar. 3, 1992 to Spangler. This process includes bringing the paint particles into contact with a plurality of HFS by depositing a layer of HFS on the surface layer of the lower portion of the paint spray booth, then encapsulating and collecting the paint particles. This method has proven sufficient, however, due to the nature of the small, lightweight HFS particles, it is not a feasible material for many water wash booths. Additionally, there remains a need for a portable paint collection containment system, that may significantly reduce the amount of water required in the paint booth system, by re-using and reformulating the waste back into paint as well as reduce the 
         [0009]    Therefore, a device is needed to employ and utilize detackification agents effectively in current and newly designed booths. A system where detackification of the process water is almost immediate and is cheaper than the conventional polymer detackification employed in current paint booth systems, and that re-uses and reformulates the waste back into paint as well as reduces the solvent emissions. 
       SUMMARY OF THE INVENTION 
       [0010]    One aspect of the present disclosure includes a paint reclamation clarifier system in communication with a sump tank in a paint booth containing a carrier fluid for capturing paint droplets and a conduit for transporting the carrier fluid mixed with paint droplets to the reclamation clarifier system. The clarifier system includes an influent port, a detackification agent inlet, a sludge tank in a lower portion of the clarifier for collecting the dispersed carrier liquid, where the paint droplets bond with the agent and settle to the bottom of the sludge tank, a sludge outlet, and, at least one effluent port located on or near an upper portion of a sidewall of the clarifier system permitting unsettled material to exit from the clarifier. 
         [0011]    In another aspect of the present disclosure, method of reclamation and clarification of paint droplets from a carrier fluid comprising the steps of introducing a carrier fluid containing paint droplets from a sump tank of a paint booth into a mixing containment chamber of a paint reclamation clarifier system, adding a detackifying agent through a detackification inlet into the mixing containment chamber of the paint reclamation clarifier system, placing the carrier fluid containing paint droplets into rigorous contact with the detackifying agent within the mixing containment chamber, directing detackified paint sludge out of the paint reclamation clarifier through a sludge outlet, whereby the sludge is created when paint droplets from the carrier fluid bond with the detackifying agent and settle to the bottom of the sludge tank, and, directing unsettled material out of the clarifier through one or more effluent ports located on or near the sidewall of the clarifier. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is a sectional view of an illustrative water-wash paint spray booth. 
           [0013]      FIG. 2  is a sectional view of a paint reclamation clarifier system of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    A representative paint booth  10  suitable for carrying out an embodiment of the present disclosure is shown in  FIG. 1 . The paint booth  10  is adapted for use in industrial paint operations. The illustrated paint booth  10  is a conventional down draft, water wash type paint spray booth having a paint application station disposed in the paint booth  10  and includes one or more spray guns  15  or other automated painting devices connected to a source of paint (not shown), the operation of which may be controlled automatically, by robot or human operator. As illustrated in the drawing, an article  13  to be painted is transported through or placed in the paint booth  10  by conventional means, including conveyors, stands, mounting or suspending apparatus, or other means known to those skilled in the art. 
         [0015]    The paint booth  10  has an open metal grate floor  14  or the like separating the paint booth  10  into an upper paint spray chamber  16  and a lower sump or sludge tank  18 . The paint booth  10  also includes a supply of water or an aqueous bath  20  within the sludge tank  18 . The aqueous bath  20  includes a top surface  21  separated by a prescribed distance from the grate floor  14 . 
         [0016]    Exhaust fans  24 , 26  are disposed in one or more exhaust air conduits  28  and are in flow communication with the paint booth  10 . The exhaust fans  24 , 26  provide for the movement of air out of the paint booth  10 . Flow of air into the paint booth is typically accomplished via make up air system. The make-up air system forcibly introduces a volume of air via a plenum (not shown) into the upper paint spray chamber  16 , through the metal grate floor  14  to the sludge tank  18 . The flow of air continues out one or more exhaust air conduits  28  via one or more exits or the like, that lead to exhaust air conduits and ultimately to the external environment. The exits are preferably disposed adjacent to the sludge tank  18  and proximate the top surface  21  of the aqueous bath  20 . 
         [0017]    As the air stream flows through the upper paint spray chamber  16  of paint booth  10 , paint over-spray is entrained in the air stream. Such paint overspray particles or compounds are directed or transported with the flowing air stream from the upper paint spray chamber  16  of the paint booth  10  and through the open metal grate floor  14 . After passing through the grate floor  14 , the air stream containing the over-spray paint particles or droplets  11  is directed into sludge tank  18 . Air stream flow volume through the paint booth  10  is preferably limited to about 50-100 cubic feet per second. Such a flow profile is sufficient to cause the over-spray paint particles and droplets carried by the air stream to fall from the air stream to the top surface  21  of the aqueous bath  20 . Such velocity profile, however, does not substantially interfere in the painting operations. The optimum velocity of the air stream at which the over-spray paint particles or droplets  11  will most effectively gravitationally separate from the air stream is a function of the mass and size of the over-spray particles and droplets  11 , which may be determined empirically for each industrial painting operation employing the above-described technology. 
         [0018]    Overspray paint particle laden wash water or aqueous bath sump fluid  20  is introduced to the paint reclamation mixing containment collection system or paint reclamation clarifier system  60  of  FIG. 2  at the influent port  42  optionally via paint booth exit conduit  34 . The influent port  42  may have a lid (not shown) (for example, screw-on, flip top, swivel). The paint reclamation clarifier system  60  also includes a detackifying agent inlet  52 , at least one wash water outlet or effluent ports  58  located on or near a sidewall of the paint reclamation clarifier system  60 , a sludge outlet  56 , and a mixing containment chamber  62 . The at least one effluent ports  58  may be aligned vertically at varying height levels along the side wall of the clarifier system  60  providing initial horizontally directed flow, or may be near yet outboard of the sidewall, with vertically directed flow, as would be understood by one skilled in the art. 
         [0019]    A batch or continuous flow of powderous, gelatinous, or liquid detackification agent (not shown) is added to the mixing containment chamber at the detackification agent inlet  52 . The detackification agent inlet  52  may be shaped as a hopper with a volumous area for conveniently allowing a user to pre-fill the detackification agent inlet  52  with detackification agent. The detackification agent inlet  52  may include a cover  54  which may be hingedly connected to the top of the detackification agent inlet  52 . 
         [0020]    The mixing containment chamber  62  includes an upper section  63  and a lower section  64 . The paint reclamation clarifier system  60  may be cylindrical and generally shaped for gravitational fluid flow. The upper section  62  is closed at its upper end (except for the inlet areas). The lower portion  66  of the paint reclamation clarifier system  60  may have a larger overall volume than the mixing containment chamber  62 , and the mixing containment chamber  62  may be partially contained within the lower portion  66  of the paint reclamation clarifier system  60 . The upper end of the lower portion  66  is closed from the open atmosphere and operates to direct the effluent towards a weir  68 . Decant valves associated with the plurality of effluent ports  58  may operate to allow directed material flow. 
         [0021]    The weir  68  (along with a baffle system) located outside of the mixing containment chamber  62  provides the opportunity to re-introduce the detackification agent and or encapsulated process material that may be floating, back into the mixing containment area  62  via a pump system, or optionally may be siphoned off with a pumpless return. Additionally, the process material may be directed to a dewatering device (not shown), described further below. 
         [0022]    Optionally, the process water or carrier fluid paint mixture  36  may be pumped into the mixing containment chamber  62 . However, it may be possible to send process water through the containment chamber  62  either by gravity (this depends on the location of the clarifier) or by siphon. The system may optionally have two pumps if gravity or siphoning is not an option. 
         [0023]    Within the upper section  63  of the mixing containment chamber  62 , fluid at the influent port  42  and the detackification agent from the detackification agent inlet  52  are forced together through strong circulation currents. When the paint booth process water  36  is high velocity pumped into the mixing containment chamber  62 , the paint droplets  11  come in forced contact with the detackification agent. Since the detackification agent is contained (with a closed and sealed top)  54 , a rigorously strong washing effect occurs when the process water  36  is directed through the layer of detackification agent. As a result, the paint droplets  11  in the process water  36  become coated with detackification agent, within the mixing containment chamber  62 . With continuous flow of process water  36  turbulently mixing through the detackification agent in the mixing containment chamber  62 , the droplets  11  which are currently floating are continuously turned over and beat into the water beneath the layer of detackification agent within the containment chamber  62 . 
         [0024]    A mixing dispersion device  70  may optionally be located at the upper end of the upper section  60  of the mixing containment chamber  62 . The mixing dispersion device  70  may operate to disperse the paint booth process water  36  as an influent (through conduit  34  or via a batch process) in an upper portion of the mixing chamber  62  into contact with a detackification agent. The device  70  may be of any shape or undergo any process action to facilitate the forced flow contact of the detackification agent into contact with the paint booth process water  36  from the influent port  42 , such as by rotation, agitation, oscillation, vibration, or the like, or may undergo no movement at all. By way of example only, the mixing dispersion device  70  may be an inverted cone shape, a bowl shape, a two-or more headed tubular spout shape, or may be directly connected to the influent port  42  to facilitate further process water  36  flow. 
         [0025]    Over a period of time, the solids begin to sink and the detackified paint sludge or treated fluid may exit from the paint reclamation clarifier system  60  at the sludge outlet  56 . Depending on the flow rate and volume of material used, a portion of the detackification agent may be pushed beyond the central tubular mixing containment section  62 , and may rise to the top of the surface, as well as the processed encapsulated sludge which may rise, remain suspended, or sink. The material that rises to the top of the surface may be re-introduced into the clarifier system  60  for additional treatment, or optionally into the paint booth lower sump tank  18 , via the plurality of effluent ports  58 . Additionally, this material that rises may be transported to a dewatering device (not shown). The material that is suspended will eventually settle over a period of time (likely less than 24 hours, or even within a few minutes given appropriate parameters). The treated material that sinks or remains suspended (at various levels of solids concentration) may be removed from the sludge outlet  56  at the bottom of the paint reclamation clarifier system  60 . The settled paint sludge material may be sent to the clarifier  60 , or to a dewatering device (not shown), or optionally back into the lower sump tank  18  of the paint booth  10 . As is known, the dewatering device may be a filter, centrifuge, decanter, hydrocyclonic separator, filter press or the like. 
         [0026]    Once collected, detackified paint droplets or sludge (and any of the aqueous solution collected therewith) is preferably transferred to a processing reservoir and optionally, conditioned with various materials to remove bacteria and otherwise aid in the recycling process. To remove the bacteria a biocide or other solution such as hydrogen peroxide is added to the processing reservoir to kill the bacteria. If necessary, the mixture (i.e. aqueous bath solution and detackified paint sludge) may then be transferred to a de-watering device for removal of the water. The remaining material may subsequently be dried to a moisture content of less than about 5 percent, and preferably a moisture content of less than about 2 percent. The dried, detackified, paint over-spray is then particulized to a size less than about 20 microns and dissolved in an appropriate solvent. The process for transferring, conditioning, de-watering, drying, and particulizing (e.g. milling) etc. are now well known to those persons skilled in the art. 
         [0027]    In some higher volume processing situations, the carrier fluid/detackification agent mixture may be fed into a separator tank (not shown). The mixture in the tank may sit in the tank for a period of time for further separation. The upper portion of the mixture in the tank, or the detackification slurry, may be sent to the paint reclamation clarifier system  60 . The lower portion of the mixture in the tank, or the effluent, may be sent back to the paint booth  10 . The detackification slurry may intermittently be removed from the separator tank, at automatically set intervals, or at manually set times. 
         [0028]    It will be understood that the paint reclamation clarifier system  60  can be of varying size and shape, but may, as an example, hold approximately 500 gallons of water and 2 cubic feet of detackification agent in one batch. 
       INDUSTRIAL APPLICABILITY 
       [0029]    The preferred paint reclamation or paint recovery process is initiated with the detackification of the paint particles and droplets using the detackification agent. The encapsulated paint particles and droplets typically remain buoyant for a period of time, during which time the encapsulated paint particles and droplets can be removed and collected from paint reclamation clarifier system  60  via the sludge outlet  56  or other collection processes. 
         [0030]    As indicated above, various materials can be added to the recycling materials (paint and silica) during the aforementioned process to aid the processing of the material as well as to complete the recycled paint product. In addition, specific additional ingredients such as binders, plasticizers, stabilizers, pigments, flow control agents, etc. can be included to restore properties to the recycled paint product that may have been lost during the original spraying operation. 
         [0031]    It will be appreciated that the foregoing description provides examples of a paint reclamation clarifier and mixing chamber system. However, it is contemplated that other implementations of the disclosure may differ in detail from the foregoing examples, as would occur to those skilled in the art. All references to the disclosure or examples thereof are intended to reference the particular example being discussed at that point and are not intended to imply any limitation as to the scope of the disclosure more generally. All language of distinction and disparagement with respect to certain features is intended to indicate a lack of preference for those features, but not to exclude such from the scope of the disclosure entirely, unless otherwise indicated. 
         [0032]    Recitation of ranges of values or dimensions herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. Accordingly, this disclosure includes all modifications and equivalents of subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the disclosure unless otherwise indicated herein or otherwise clearly contradicted by context.