Patent Publication Number: US-2021162444-A1

Title: Powder coating systems with air or liquid cooled cyclone separators

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of U.S. patent application Ser. No. 15/521,283, filed Apr. 22, 2017, which claims the benefit of International Application No. PCT/US2015/060163, filed Nov. 11, 2015, which claims the benefit of U.S. Provisional Patent Application No. 62/078,466, filed Nov. 12, 2014, the entire disclosures of which are hereby incorporated by reference as if set forth in their entirety herein. 
    
    
     TECHNICAL FIELD OF THE DISCLOSURE 
     This disclosure relates to powder coating systems and processes that use cyclone separators. More particularly, this disclosure relates to powder coating systems and processes that introduce controls for managing a temperature of process air introduced from the spray booth into and within a cyclone separator, and separately a cyclone separator with cooling. 
     BACKGROUND OF THE DISCLOSURE 
     Powder coating materials are typically applied to objects or workpieces by spray application apparatuses and processes. These spray application apparatuses and processes include electrostatic and non-electrostatic processes. Spray application of powder coating material from a feed center or supply to workpieces often is done in a spray booth that is used to contain and recover powder overspray that does not adhere to the workpieces during a powder coating operation. Powder overspray may be recovered from the spray booth and either recycled back to the feed center for re-use or otherwise disposed or used in other applications. A powder cyclone separator is commonly used as part of a powder recovery system whereby powder overspray entrained air is drawn from the spray booth through duct work into a cyclone separator which operates to remove powder that is entrained in the air stream. The separated powder falls to the bottom of the powder cyclone separator where it is then transferred to a receptacle. 
     Due to high temperatures of a piece being coated or within the spray booth, the powder may melt and become sticky. In conventional powder coating systems, the sticky overspray powder may adhere to various surfaces of the powder recovery system and/or become caught in the after-filter system, leading to a constant need to clean the powder recovery system and/or premature failure of the after-filter system. As such, there is a need to cool the process air as it travels through the powder recovery system. 
     SUMMARY OF THE DISCLOSURE 
     A cyclone that lowers the temperature of at least a portion of an interior surface of the cyclone is disclosed. In an embodiment, a cyclone includes a body configured to receive process air, where the body includes an exterior surface and an interior surface, and an enclosure that encloses at least a portion of an exterior surface of the body. The enclosure delimits an enclosed volume between an interior surface of the enclosure and the exterior surface of the body. The enclosure is also configured to retain a cooling medium in thermal exchange with the exterior surface of the body enclosure. The enclosure can be fluid-tight to retain a fluid that is in thermal exchange with the enclosed exterior surface, when the cooling medium comprises a liquid. The cooling medium can also be a gas. Additional embodiments are presented herein. 
     In some embodiments, the cyclone can include a pump configured to move the liquid through the enclosed volume from a fluid inlet of the enclosure to a fluid outlet of the enclosure. The body can include a first portion and a second portion, where the first portion and the second portion can be configured to align with each other along a first axis, and where the second portion can be pivotally attached to said first portion by a joint. The second portion can be configured to pivot about the joint between a first position and a second position, and the second portion can be configured to align with the first portion along the first axis when the second portion is in the first position. The second portion can include a powder outlet end that is releasably connectable to a powder receptacle. The powder receptacle can be moveable away from the cyclone when the second portion is released from the powder receptacle. A cooling unit can be configured to reduce a temperature of the cooling medium. 
     A powder coating system with air being admitted or added to a process air flow between a spray booth and a cyclone is also disclosed. In an embodiment, the powder coating system includes a spray booth including a recovery duct for powder overspray, where the recovery duct has a recovery duct inlet and a recovery duct outlet. The powder coating system also includes a cyclone comprising a powder inlet, and a suction duct that connects the recovery duct outlet with the cyclone powder inlet, where the recovery duct and the suction duct delimit a powder overspray flow path from the spray booth to the cyclone. The powder coating system also includes an opening for admitting air from an exterior of the powder coating system into the powder overspray flow path. 
     The recovery of admitted air may optionally be ambient air that is admitted into a powder flow path and added to process air flow before the process air flow enters the cyclone. In another embodiment, a powder coating system that utilizes adding air to process air flow before the process air flow enters the cyclone. 
     In some embodiments, the opening can be provided in the recovery duct. The powder coating system can further include a moveable cover configured to adjust a size of the opening. The ambient air may combine with process air that travels from said spray booth to the cyclone via the powder overspray flow path. 
     The powder coating system can further include an enclosure that encloses a portion of an exterior surface of the cyclone, where the enclosure delimits an enclosed volume between an interior surface of the enclosure and the exterior surface of the body. The enclosure can be configured to retain a cooling medium in thermal exchange the said enclosed exterior surface. The cyclone can include a first portion and a second portion, where the first portion and the second portion may be configured to align with each other along a first axis, and where the second portion may be pivotally attached to said first portion by a joint. The second portion may be configured to pivot about the joint between a first position and a second position, where the second portion may be configured to align with the first portion along the first axis when the second portion is in the first position. The second portion may include a powder outlet end that is releasably connectable to a powder receptacle. The powder receptacle may be moveable away from said cyclone when the second portion is released from the powder receptacle. 
     In accordance with another embodiment, a method is provided for reducing temperature and/or diluting a powder entrained air flow from a spray booth to a cyclone. In an embodiment, the method includes reducing the temperature of an interior surface of the cyclone compared to what the temperature of the interior surface would be in the absence of thermal exchange with the fluid. For example, process air may be admitted into the cyclone through an inlet opening of the cyclone. An inlet temperature of the admitted process air may be measured at a location proximate to the inlet opening a required amount of cooling energy may be determined based on the inlet temperature. 
     These and other aspects and advantages of the inventions, embodiments and the disclosure herein will be readily understood and appreciated from the following detailed description hereinafter and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front perspective view of an embodiment of a powder coating system in accordance with the present disclosure; 
         FIG. 2  is a rear perspective view of the embodiment of  FIG. 1 ; 
         FIG. 3  is an elevated side perspective view of the embodiment of  FIG. 1  from the side shown in  FIG. 2 ; 
         FIG. 4  is a side view of the embodiment of  FIG. 1 ; 
         FIG. 5  is an enlarged back side perspective view of an enclosure for a cyclone of the embodiment of  FIG. 1  with the enclosure walls shown in transparency for illustrative purposes; 
         FIG. 6  is an enlarged perspective view of the enclosure depicted in  FIG. 5  from an opposite side with the enclosure walls shown in transparency for illustrative purposes; 
         FIG. 7  is an enlarged perspective view of the enclosure depicted in  FIG. 5  with a back wall of the enclosure removed; 
         FIG. 8  is an enlarged cross-sectional view of the embodiment of  FIG. 1  taken along line  8 - 8  in  FIG. 2 ; 
         FIG. 9  is a cross-sectional view of the embodiment of  FIG. 1  taken along line  9 - 9  of  FIG. 2 ; 
         FIG. 10  is a side view of a lower portion of a spray booth of the embodiment of  FIG. 1  with a side booth wall of the spray booth removed; 
         FIG. 11  is a side view of the embodiment of  FIG. 1 ; 
         FIG. 12  illustrates a prior art powder coating system such as may be used with the present embodiments presented in this disclosure; 
         FIG. 13  is an enlarged view of a powder receptacle; 
         FIG. 14  is a perspective view of a lower portion of a powder recovery system of the embodiment of  FIG. 1  showing a moveable lower portion of a cyclone in View B; 
         FIG. 15  is an enlarged elevation view of a hinged lower portion of a cyclone of the embodiment of  FIG. 11  showing a pivoted position in View C; 
         FIG. 16  is a side perspective view of a second embodiment of a powder coating system in accordance with the present disclosure; 
         FIG. 17  is a perspective view of a powder overspray recovery system of the powder coating system shown in  FIG. 16 ; 
         FIG. 18  is an enlarged back side perspective view of an enclosure for a cyclone of the powder coating system shown in  FIG. 16  with the enclosure walls shown in transparency for illustrative purposes. 
     
    
    
     DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS 
     Although the various embodiments herein illustrate a particular form and structure of a powder recovery cyclone separator, also referred to herein as a cyclone, the various inventions may be used alone, in various combinations and/or collectively with different cyclone designs. The basic structural features of a cyclone that the present disclosure utilizes is a first or upper portion that typically is cylindrical and a second or lower portion that typically is conical. A cyclone may have many other optional structural features which form no required structure in order to practice the inventions herein. Conventionally, the upper portion includes an intake section that receives a flow of powder entrained air at a tangential inlet to the intake section, and a powder recovery section through which cyclonically separated powder falls to an outlet. All other exemplary embodiments herein of various components of a cyclone or a powder coating system, such as but not limited to the spray booth, feed center, spray guns and so on are optional design features that may be selected for a particular spray coating operation or processes. In other words, the cyclone concepts disclosed herein may be used with a wide variety of cyclone and system features including a feed center for supplying powder coating material, spray guns, electronic control systems for the spray booth, spray guns, gun control systems, gun movers, reciprocators, oscillators, overhead conveyor systems, and so on. The inventions also are not limited to any particular spray technology, and may include but not limited to electrostatic, tribo-electric, non-electrostatic, hybrid technologies, as well as automatic and manual application systems, as well as being used with dense phase and/or dilute phase powder conveyance technologies. 
     INTRODUCTION 
       FIG. 12  illustrates a prior art powder coating system  10  that includes a spray booth  12  and a powder overspray recovery system  14 . The spray booth  12  in this embodiment may be supported on a structural frame (not shown) above the shop floor. While a prior art powder coating system to provide context for understanding the present inventions is described herein, the present inventions may be used with many different powder coating systems, either those known or that may be later developed. 
     In the prior art design of  FIG. 12 , a generic or typical spray booth that may be traditional in design includes an overhead conveyor to transport parts through the spray booth for a coating operation. While the spray booth depicted in  FIG. 12  includes an overhead conveyor, one of ordinary skill in the art would appreciate that the exemplary embodiments disclosed herein may be used for coating operations of pipe and other tubular workpieces, in particular long sections of pipe, as well as large diameter pipe that may not hang from a conveyor. In particular, the dimensions of the pipe may prevent it from being hung from a conveyor. Moreover, one of ordinary skill in the art would appreciate that the embodiments disclosed herein are not limited to any particular spray booth design. 
     A powder recovery system  14  commonly is used to recover powder overspray that is generated by a plurality of powder coating material application devices  16  such as, for example, a spray gun, are used to coat workpieces W with powder coating material P as the workpieces W advance through the spray booth  12  interior. These application devices  16  may include automatic and manual spray guns, for example. Automatic spray guns often are mounted on a gun mover system (not shown) which may include a reciprocator or oscillator. The gun mover system may be used to both extend and retract the spray guns with respect to the spray booth  12  and also may be used to produce an up/down oscillatory motion of the guns during a coating operation. The spray guns  16  may be selected from any number of spray gun designs, including but not limited to an ENCORE® spray gun available from Nordson Corporation, Westlake, Ohio. The spray guns  16  may be electrostatic, non-electrostatic, tribo-charging or other designs and spraying technology may be used. A series of vertical gun slots or openings in the spray booth walls may be provided for automatic spray guns, and the spray booth  12  may also include other openings through which an operator can manually spray workpieces. 
     A feed center  18  may be provided that contains a supply of powder coating material P that will be applied the workpieces within the spray booth  12 . The feed center  18  for example may include any number of hoppers, boxes or other containers of powder, along with suitable pumps and hoses to feed material to the one or more spray guns  16 . A powder hose  20  connects a powder input of the spray gun  16  to an output of a powder pump (not shown) which may be located in the feed center  18  or other convenient location. Not all powder coating systems utilize a feed center and in other embodiments, powder coating material may be supplied to the spray gun  16  simply using a pump that draws powder from a box or hopper or other container. An example of a feed center  18  is described in U.S. Pat. No. 7,325,750 for POWDER COATING SYSTEM WITH IMPROVED OVERSPRAY COLLECTION, issued Feb. 5, 2008, and also U.S. Pat. No. 8,033,241 for SUPPLY FOR DRY PARTICULATE MATERIAL, issued Oct. 11, 2011; the entire disclosures of which are fully incorporated herein by reference. However, many different feed centers or other suppliers for powder coating material may be used as needed. The feed center described in U.S. Pat. No. 7,325,750 may, for example, be used with Venturi type pumps for dilute phase systems and the feed center described in U.S. Pat. No. 8,033,241 may be used, for example, with dense phase pumps for dense phase systems. But the present inventions may be used with dense phase or dilute phase pumps and powder spray systems. 
     A suitable operator interface to a control system (not shown) may be provided to control operation of the spray guns  16 , the powder recovery system  14 , the spray booth  12  including an optional overhead conveyor C, the gun mover system, gun controls, feed center and pump controls and so on, as is well known to those skilled in the art and need not be described herein to understand and practice the present inventions. The control system and the operator interface may be selected from any number of well known control system concepts as are well known to those skilled in the art, or specifically designed for a particular system. 
     In the example of  FIG. 12 , the powder overspray recovery system  14  is realized in the form of a powder cyclone separator  30 . Depending on how much powder overspray needs to be extracted from the spray booth, or the geometric constraints of the system, a single cyclone, twin cyclone or more cyclones alternatively may be used. The exemplary embodiments herein illustrate a twin cyclone configuration, but the inventions and concepts herein may optionally be used with a single cyclone configuration. 
     A blower and after filter system  23  may include an after filter system  24  and a suction fan  22  that are in fluid communication through a duct  26  with an exhaust outlet  28  of the cyclone  30 , and provide the energy and air flow required to generate a vortex  36  within the cyclone  30  for operation of the cyclone powder recovery system  14 . The fan  22  produces suction that draws a large air flow into the cyclone  30 , in the form of a substantial powder entrained air flow pulled from the spray booth  12  interior, to an intake duct  32  of the cyclone. The cyclone  30  commonly includes a tangential powder inlet  34  (relative to a vertical axis of the cyclone) to cause the familiar cyclonic circulation or vortex  36  that causes separation of powder coating material from the air. 
     The air flow produced by operation of the powder recovery system  14  also produces a substantial flow of air into and through the spray booth  12 , sometimes referred to as containment air. The containment air flow prevents the loss of powder overspray outside the spray booth  12 . Powder overspray that does not adhere to the workpiece W during a powder coating operation falls by gravity and also may be assisted to flow by the containment air into a recovery duct  38 . The powder entrained air is thus drawn into the cyclone  30  during operation of the after-filter fan  22 . 
     Typically, the after filter system  24  and the fan  22  draw a substantial flow of powder entrained air into the cyclone  30  and the separated powder descends as indicated by the arrows  40  to a cyclone outlet  42 . From the cyclone outlet  42  the recovered powder may be returned to the feed center  18  or otherwise dumped to waste or reclaimed in some other manner. The powder entrained air that is pulled into the cyclone tangential inlet  34  via the intake duct  32  may be drawn through a vertical extraction duct  44 . 
     Powder overspray that has been separated by the cyclone  30  may be recovered from the cyclone outlet  42  and returned to the feed center  18 , as is commonly done if the powder will be reused, or alternatively may be conveyed to another container or receptacle or dumped to waste. A transfer pump  46  may be used to pull the recovered powder from the outlet  42  of the cyclone  30  to transfer the powder back to the feed center  18  through a transfer powder hose  60  or otherwise disposed. The cyclone  30  may include an optional transfer pan (not shown in  FIG. 12 ) that provides an interface between the transfer pump  46  and the cyclone outlet  42  for collection of the powder that falls from the cyclone  30  interior. A transfer pan is commonly used in twin cyclone configurations as well. 
     The spray booth  12  may be generally rectangular in shape although other shapes and configurations may conveniently be used. A spray booth  12  will typically have a longitudinal horizontal axis X into the plane of the drawing for  FIG. 12 , which is typically the axis along which the conveyor C moves the workpieces W through the spray booth  12 . The spray booth  12  may have a ceiling  48  supported by one or more vertical sides or walls  50 , and a floor  52 . As represented by the arrow  54 , powder overspray tends to fall to the floor  52  or otherwise become entrained in the containment air such that powder entrained air passes through openings, duct work or other openings in or around the floor  52  to an exhaust opening that is in fluid communication with the recovery duct  38 . The ceiling  48  may include an overhead conveyor slot  56  that allows hangers  58  to extend from the conveyor C to suspend workpieces inside the spray booth  12  interior. 
     All of the panels for the spray booth structure, including by not limited to the floor  52 , ceiling  48 , walls  50  and so on may each be made of composite materials including a foam core panel and gelcoat inner surface such as sold by Nordson Corporation in powder coating booths as an Apogee® panel structure. Other materials may alternatively be used as required, for example, PVC walls and panels. The Apogee® panel construction is also described in U.S. Pat. No. 6,458,209 for POWDER COATING BOOTH CONTAINMENT STRUCTURE issued to Shutic, Oct. 1, 2002, the entire disclosure of which is fully incorporated herein by reference. 
     However, alternative spray booths such as, for example, in the exemplary embodiments herein, may have walls, ceiling and floor made of metal such as stainless steel sheet metal. For example, in fusion bond epoxy (“FBE”) pipe coating operations where a pipe may be heated up to 450° F. prior to being introduced into the spray booth structure, the surface temperature of the pipe being coated may elevate the interior surfaces of the spray booth enclosure beyond 140° F. This may especially be the case when the pipe being coated has a large diameter or is of heavy wall steel construction. The surfaces of the pipes entering the spray booth may also be in close proximity to the structure surrounding the entrance to the spray booth so as to minimize a loss of surface temperature of the pipe prior to the coating operation. In such operations, a plastic or composite spray booth enclosure may not be practical due to its inability to withstand such high temperatures. When gas-fired furnaces are employed, infrared saturation of the entry side of the booth enclosure may be common. As such, induction coils are typically used to heat the pipe. In such instances, the spray booth enclosure may need to be constructed from a non-ferrous material such as stainless steel to prevent heating of the booth walls due to electromagnetic energy take-up. 
     DETAILED DESCRIPTION 
     As used herein, the term “process air” refers to the powder entrained air flow that is drawn through the spray booth  12  in order to recover powder overspray. Process air therefore is comparable to what is referred to in the art as containment air which is drawn by the after-filter system  23  through a cyclone from the spray booth. The term “admitted air” means an air flow that is added to the process air flow for purposes described below. Admitted air may be the optionally unconditioned ambient air of the environment that surrounds the powder coating system. But admitted air may alternatively, if needed, be ambient air that has been conditioned, for example as to temperature, relative humidity and so on, prior to being added to the process air flow. Therefore, process air is an air flow rate and volume that is produced by operation of the after-filter system  23  through the cyclone and the spray booth absent the introduction of admitted air through a provided opening as described below. The term “powder flow path” as used herein refers to duct work or other pathways that contain powder overspray entrained air that flows from the spray booth into the cyclone. 
       FIGS. 1-4  illustrate different views of an embodiment of a powder coating system  70 . The powder coating system  70  includes a spray booth  72  and a powder overspray recovery system  74 . The spray booth  72  may be a multi-walled construction made of stainless steel sheet metal and has a front opening  76  that receives one or more spray guns (not shown in  FIGS. 1 and 2 , but see  FIG. 12  for an example) by which powder coating material is applied to a workpiece W. The powder coating system  70  may include the additional system components as described with reference to  FIG. 12  as needed. The spray booth  72  may include lateral openings  78  through vertical walls  80  which a workpiece W, for example a pipe as shown, may pass through the spray booth  72  during a powder coating operation. The various drawings omit structure that supports the workpiece W, passes the workpiece W through the spray booth  72 , and optionally but typically also rotates the workpiece W about the longitudinal axis X thereof. The powder coating material may be applied by the spray guns generally on an alignment that is transverse the axis X. 
     The workpieces W need not be pipe, but as an example, the spray booth  72  may be designed to accommodate very large pipe, for example, fifty-six inch pipe or larger in diameter. Smaller pipe diameters may also be used. The workpieces W typically are also heated so as to help the coating material adhere to the workpiece as it passes out of the spray booth and on for further processing. As an example, the workpiece W may be heated to approximately 450° F. or higher, although lower temperatures may also be used as needed for different workpiece materials and powder coating material. Due to the high heat of the workpiece, the process air may be on the order of approximately 140° F. inside the spray booth  72 . This temperature or other process air temperatures can be near the glass transition temperature of the powder coating material. 
     Powder overspray becomes entrained in the containment air that is drawn from the spray booth  72  by the after-filter system (not shown in  FIGS. 1 and 2  but see  FIG. 12  for an example) and this powder entrained air as noted above is referred to herein as the process air. 
     The powder recovery system  74  may be used to recover this large quantity of high temperature powder overspray. The powder recovery system  74  includes a cyclone  82  (which is partially in view in  FIGS. 1 and 2 ). A process air extraction or suction duct  84  provides a powder flow path from a process air outlet  86  of the spray booth  72  to a powder inlet  88  of the cyclone  82 . A twin or double cyclone  82  is illustrated but alternatively a single cyclone or more than two cyclones may be used as needed. An enclosure  90  encloses at least a portion of the cyclone  82 . In the case of a single cyclone, it may well be that the enclosure  90  could surround most or all of the cyclone, but because of the position of the powder inlet  88  to the cyclone  82  it can be difficult in some cyclone designs to have the enclosure  90  enclose the entire cyclone  82  structure. An exhaust outlet  92 , which may include an exhaust duct, is connectable to an after-filter system  23  and fan  22  (see  FIG. 12 ). The after-filter system  23  is omitted in  FIGS. 1 and 2  for clarity. The exhaust outlet  92  of the cyclone  82  receives the exhaust air from the cyclone  82  in which the exhaust air is the process air with most of the entrained powder removed by the vortex and cyclonic action, but some powder typically remains entrained in the exhaust air flow. This exhaust air is then filtered by the after-filter system. The cyclone  82 , particularly a stationary upper portion  100 , may be supported on the shop floor or other foundation with a frame  94  that typically is fixed in position for stability. However, as further described below, a lower portion  102  of the cyclone  82  may be moveable for cleaning and color change operations. 
       FIGS. 5-7  illustrate in more detail the enclosure  90  for the cyclone  82 . The enclosure  90  may be realized in the form of a jacket or shell  96  that is supported on the frame  94 . The jacket  96  forms a fluid-tight enclosure that at least partially surrounds the cyclone body  98 . The cyclone body  98  comprises the cyclone wall structure within which the process air becomes drawn into a vortex for separating powder from the air. The cyclone body  98  typically may include a cylindrical section  98   a , an upper conical section  98   b  and a lower conical section  98   c . The cylindrical section  98   a  and the upper conical section  98   b  may be welded together or otherwise held together and preferably are stationary and may be fixed to the frame  94 . The cylindrical section  98   a  and the upper conical section  98   b  form a cyclone upper portion  100  (see  FIG. 11 ). The lower conical section  98   c  forms a cyclone lower portion  102  (see  FIG. 11 ). Although in this embodiment the lower cyclone portion  102  is moveable (as further described below) such need not be the case. In an embodiment in which the lower cyclone portion  102  is fixed, then the enclosure  90  optionally may enclose all or a portion of the cyclone lower portion  102  as well. 
     The enclosure  90  encloses a portion of the cyclone body  98 , for example, a portion of the cyclone upper portion  100 . The enclosure  90  may only enclose a portion of the cyclone body  98  due to, for example, the geometry of the powder inlet  88 . In alternative embodiments, for example an embodiment with a single cyclone, the enclosure  90  may enclose an entire upper portion of the cyclone. 
     The enclosure  90  may include a series of panels  104  that are sealed in a fluid-tight manner as needed and supported on the frame  94 . The panels  104  are shown in transparency in  FIGS. 5 and 6 , but may be made of a suitable material for containing a fluid  106 . In an embodiment, the fluid may be water. Depending on the cooling energy needed to reduce the temperature of the cyclone interior surfaces  108  (see  FIG. 7 ) to a desired temperature, the water  106  may be simply taken from a commercial supply such as tap water, or may be conditioned as needed to reduce the water temperature. The enclosure  90  may include fluid inlets  110  and fluid outlets  112 , along with a pump  114  that may be used to circulate the fluid through the enclosure  90 . In an embodiment it is preferred but not required that the fluid enters and exits the enclosure  90  at distant locations to maximize flow through the enclosure  90  and for contact and thermal exchange with as much surface area of the exterior surface  116  of the cyclone body  98 . Multiple inlets  110  and outlets  112  shown in the figures may be used as needed. Although only used as an example, for a typical twin cyclone  82  the enclosure  90  may contain a volume of 400 gallons of the fluid  106  or more, and for other embodiments the enclosure  90  might be smaller and contain less than 400 gallons of the fluid  106 . The dimensions of the enclosure  90  and volume capacity will in part be determined by the dimensions of the cyclone  82 , as well as the volume and flow rate of fluid  106  needed to provide the desired temperature reduction of the interior surface  108  of the cyclone  82 . Should an embodiment utilize a divider wall  118  due to the cyclone geometry, fluid passageways  120  may be provided as needed to assure even and open flow of the fluid  106  through the enclosure  90  (see  FIG. 7 .) 
     Reducing the temperature of at least a portion of the cyclone body  98  may help reduce impact fusion of powder coating material within the cyclone  82 . For example, when large pipe that is being coated is heated as described above, the process air may be hot enough that impact fusion more readily occurs on the interior surfaces  108  of the cyclone  82 . By cooling the interior surfaces  108  the cyclone  82 , this tendency for impact fusion can be reduced. In an example of the enclosure  90 , for example in an embodiment of a water jacket, water flowing through the enclosure  90  contacts the enclosed portion of the exterior surface of the cyclone body  98 , thereby being in thermal or heat exchange with the exterior surfaces  116  the cyclone body  98 . This thermal exchange will reduce the interior surface  108  temperature of the cyclone  82 . A number of variables may be adjusted or controlled to achieve the desired interior surface temperature. The cooling fluid  106 , such as water, may be used from commercial water supply, or may be cooled as needed. The fluid  106  removes heat from the cyclone body  98  and may optionally be pumped through a heat exchanger for cooling before being recycled back through the enclosure  90 . The temperature of the interior surfaces  108  of the cyclone will depend in part on the thermal conductivity between the exterior surfaces  116  and the interior surfaces  108  of the cyclone body  98 . Stainless steel sheet metal has excellent thermal conductivity but other materials may alternatively be used as needed. The enclosure  90  may optionally be insulated to increase the heat exchange efficiency. Other techniques may be used to increase the heat exchange between the fluid  106  and the cyclone body  98 . Depending on the heat exchange efficiency it may be optional to operate the pump  114  periodically rather than continuously. 
     As depicted in  FIGS. 5-7 , the enclosure  90  may not enclose a region of the cylindrical section  98   a  of the cyclone body  98 . Accordingly, this region of the cylindrical section  98   a  of the cyclone body  98  may not receive direct cooling via the fluid  106  that is introduced into the enclosure  90 . Nonetheless, powder overspray entrained in process air that first enters the cyclone body  98  via the powder inlet  88  may not fuse or stick to the interior surfaces  108  of the cyclone  82  due to its high travelling velocity as it enters the cyclone  82 . Moreover, the geometry of the cyclone  82  favors larger particles travelling closer to the interior surfaces  108  of the cyclone  82 , and such particles being larger in size are less likely to melt and stick to the inner surface of the cyclone  82 . The enclosure  90  also encloses a substantial region of the cyclone body  98 ; therefore, the partial enclosure still allows most of the surface area of the cyclone body  98  in the upper portions to be cooled. Depending on the thermal conductivity of the material forming the cyclone body  98 , this cooling may also travel into the regions that are not enclosed. Accordingly, the embodiment of the powder recovery system  74  is able to effectively reduce the impact fusion of powder coating material within the cyclone  82  even without entirely covering the cyclone body  98 . 
     By the time the powder overspray settles out of the air flow within the cyclone  82 , the powder overspray has cooled due to its travel through the cyclone upper portion  100 . Therefore, it also may not be necessary to have the enclosure  90  enclose the lower cyclone portion  102 , which may not be exposed to higher temperatures. 
     With reference to  FIGS. 8-10 , several sectional views are provided to illustrate powder flow via the process air that is drawn through the spray booth  72  and the suction duct  84  into the cyclone  82 . The spray booth  72  floor includes a recovery duct  122  at an outlet end of the spray booth. The recovery duct  122  forms a plenum for the process air  124  to exit the spray booth  72 , and is under negative pressure due to the air flow induced by the after-filter system  23 . The process air  124  flow is represented by the arrow  124  and as noted hereinabove, the process air  124  includes containment air drawn into the spray booth  72  by the after-filter system  23  via the cyclone  82 , along with entrained powder overspray. The recovery duct  122  has a recovery duct inlet  126  and a recovery duct outlet  128 . The recovery duct outlet  128  serves as the aforementioned process air outlet  86  of the spray booth  72  (see  FIG. 2 ), and is in fluid communication with an inlet  130  to the suction duct  84 . An optional cover panel  132  is provided over the recovery duct  122  so that powder overspray that is in the back region of the spray booth  72  will fall and be shed by the cover panel  132  into the recovery duct inlet  126 . The cover panel  132  may be angled to promote shedding of powder overspray into the recovery duct  122 . For example, the cover panel  132  may be for example angled at about 60 degrees relative to horizontal. An upper panel  134  of the recovery duct may include an inspection door  136  that may be opened or removed (after removal/opening of the optional cover panel  132 ) to inspect visually and clean the interior of the recovery duct  122  during color change or other maintenance activities. 
     An opening  138  is provided into the recovery duct  122 . The opening  138  may be used for admitting air  140 , preferably ambient air, from the surrounding environment of the powder coating system  10  to be added to the process air  124 . The same suction that draws the process air  124  into the recovery duct  122  through the recovery duct inlet  126 , may be used to draw the admitted air  140  into the recovery duct  122 . Preferably, but not necessarily, the admitted air enters the recovery duct  122  laterally relative to the general flow direction of the process air  124  into the recovery duct  122 . The admitted air  140  may be used for a variety of purposes. For example, the admitted air  140  may be used as supplemental air to dilute the process air  124 , because in some applications such as dense phase coating processes, the process air may be too rich in powder. The admitted air  140  may also or alternatively be used for cooling the process air  124  before the process air  124  passes into the cyclone  82 . As an example for large pipe coating operations, the process air entering the recovery duct  122  may be approximately 140° F., but by admitting cooler ambient air the process air temperature may be reduced to 120° F. These numbers are intended to be exemplary and will be different for different coating operations, powder coating materials, workpieces and so on. 
     The flow rate and volume of admitted air  140  into the powder overspray flow path through the opening  138  may be optionally controlled by providing moveable baffles or a moveable door at the opening  138  so as to allow adjustment of the amount of admitted air  140  being added. This may be useful, for example, if environmental conditions of the ambient air characteristics change. Many other techniques may be used to control the admitted air  140  flow rate and volume. 
     Although ambient air is preferred, the admitted air flow into the lateral opening  140  may be conditioned, for example by cooling or reducing humidity. It is also preferred that the admitted air  140  enter the recovery duct  122  near or in close proximity to the recovery duct outlet  128 . More generally, it is preferred that the admitted air  140  be added to the process air  124  before the process air  124  enters the cyclone. By having the opening  138  to the recovery duct  122 , the admitted air  140  mixes with the process air before traveling the distance of the suction duct  84  from the spray booth to the cyclone to allow further time for the process air to cool. 
     The suction duct inlet  130  receives the process air  124  flow that is combined with the admitted air  140  to provide a powder overspray flow  142  ( FIG. 10 .) The suction duct  84  has a vertical pipe section  144  and a suction duct outlet  146  that is in fluid communication with the cyclone powder inlet  88 . The suction duct  84  conveys the powder overspray flow  142  to the cyclone powder inlet  88  from the recovery duct outlet  128 . The term “powder overspray flow path” as used herein refers to the passageway and flow path  148  that conveys the powder overspray which is entrained in the containment air to form the process air  124  from the spray booth  72  to the cyclone  82 . In an embodiment as illustrated, the powder overspray flow path  148  may include the recovery duct  122  and the suction duct  84  (see  FIG. 9 .) It is preferred although not required that the opening  138  be open to the powder overspray flow path  148  in the recovery duct  122 , but alternatively the opening  138  to the powder overspray flow path  148  may be located anywhere along the powder overspray flow path  148 , for example, in the suction duct  84 . 
     Methods for cooling the process air described herein, including the use of a cyclone  82  that is cooled using an enclosure  90 , and the use of supplemental air  140  that is admitted to the process air  124  flow through an opening  138  in the powder overspray flow path  148 , may be used to manipulate or influence the rate of impact fusion of the powder overspray on the cyclone interior surface  108 . The admitted air  140  may be used to reduce the temperature of the process air  124  before the powder overspray entrained air enters the cyclone powder inlet  88 . The admitted air  140  may also be used to dilute the air/powder ratio of the process air  124 , especially for embodiments that use dense phase powder application processes. The admitted air  140  may be ambient air, and if the ambient air is in a warm environment, the cooling fluid  106  may be lowered in temperature, or the ambient air may be conditioned before being admitted into the process air  124  flow. In order to determine the needed amount of cooling provided by the fluid  106 , the powder coating system  10  may be operated with the admitted air opening  138  fully open and measuring the inlet temperature of the powder overspray flow  142  into the cyclone. The cooling fluid temperature may then be selected to provide the desired interior surface temperature of the cyclone body. 
     Although the exemplary embodiment illustrates an enclosure  90  in the form of a water jacket to provide thermal transfer to lower the temperature of the interior surface  108  of the cyclone, other techniques and arrangements may be used to lower the temperature of the interior surface of the cyclone  82 . For example, in the separate embodiment depicted in  FIGS. 16-18 , an enclosure  290  may be used for containing cooled air  206  instead of a liquid. 
     Higher temperature of the powder overspray in some embodiments may result in powder agglomeration in the exhaust air from the cyclone. A screw conveyor and hopper (not shown) may be used in the after-filter system  23  to break up these agglomerations before the powder is recovered for re-use. 
     The fluid  106  may be internally recycled through the enclosure  90 , although depending on the temperature increase in the fluid it may be necessary to chill the fluid before it reenters the enclosure  90 . Alternatively, rather than recycling the fluid  106 , the fluid that leaves the enclosure  90  may be used to help quench the workpiece W as it exits the spray booth  72 . 
     With reference to  FIGS. 11 and 13 , the cyclone  82  includes the stationary upper portion  100  and the lower portion  102 . The lower portion  102  of the cyclone is not enclosed by the enclosure  90  because in some embodiments it may be desirable to have the lower portion  102  moveable for cleaning and color change operations. In an embodiment, the lower portion  102  may include a lower conical section  150  and a receptacle  152 . The receptacle  152  receives the powder coating material that is separated during operation of the cyclone  82 . The receptacle  152  may include a conical inlet  154  that is releasably connectable to a lower end of the lower conical section  150 . For example, latches  156  may be used to releasably secure the receptacle  152  to the lower conical section  150  (see  FIG. 13 ). When released from the lower conical section  150 , the receptacle  152  may be removed or relocated for color change or cleaning and a new receptacle moved into position under the cyclone and connected to the lower conical section  150 . The receptacle  152  may include casters  158  or other suitable means to more easily move the receptacle to a desired location. 
     With reference to  FIG. 14 , the lower conical section  150  may be connected to the upper portion  100  of the cyclone by a second set of latches  160 . A support frame  162  may be positioned under the lower conical section  150  (after the receptacle  152  has been disconnected and moved away) and raised into contact with the support frame  162 , such as by using a forklift or other suitable means. The latches  160  may then be released and as shown the lower conical section  150  moved away from the upper portion  100  of the cyclone, as represented in the view B. After cleaning, the lower conical section  150  may be repositioned and connected to the upper portion  100  of the cyclone and the support frame  162  then removed. 
     With reference to  FIG. 11  and  FIG. 15 , the lower conical section  150  of the cyclone may also be connected by a third set of latches  164  to the upper portion  100  of the cyclone with a hinge  166 . The hinge  166  may be a hinge pin  168  for example. With the second set of latches  160  connecting the lower conical section  150  to the upper portion  100  of the cyclone, the third set of latches  164  may be released thereby allowing the lower conical section to pivot about the hinge  166  and swing to a second position for cleaning or other maintenance. This second position is illustrated in  FIGS. 11 and 15  as view C. When both the hinged connection with the latches  164  and the release connection with the latches  160  are used together, in order to remove the lower conical section  150  via the support frame  162 , the latches  164  may first be released and the hinge pin  168  removed. 
     With reference to  FIGS. 16-18 , a second exemplary embodiment of a powder coating system  270  is accordance with the present disclosure is described. The powder coating system  270  may include the same spray booth  72  as the powder coating system  70  described with reference to  FIGS. 1-15 . The powder coating system  270  may also include the same suction duct  84 . As described above, the suction duct  84  includes a vertical pipe section  144  and a suction duct outlet  146 . The powder coating system  270  further includes a powder recovery system  274 . 
     As depicted in  FIG. 16 , the spray booth  72  may be coating a workpiece W with powder coating material. The powder coating material may be applied to the workpiece W via spray guns (not depicted). In certain applications, the spray booth  72  may comprise up to 40-50 spray guns. In order to improve adherence or fusion of the powder coating material to the workpiece W, the workpiece W may be heated prior to being introduced into the spray booth  72 . Excess powder coating material that does not adhere to the surface of the workpiece W may be collected at the bottom of the spray booth  72  and entrained in air that carries the excess powder or overspray powder into the powder recovery system  274 . The powder entrained air or process air may be drawn out of the bottom of the spray booth and into the powder recovery system  274  by suction that is applied by a blower and after filter system, such as the blower and after filter system  23  depicted in  FIG. 12 . 
     Due to the high temperature of the workpiece W, however, heat that radiates from the workpiece W may heat the surrounding air to temperatures of 120° F. or higher. Such temperatures may be close to the temperature at which the powder coating material may melt and become sticky. In conventional powder coating systems, the sticky overspray powder may adhere to various surfaces of the powder recovery system (such as, for example, the interior surface of the cyclone) and/or become caught in the after-filter system, leading to a constant need to clean the powder recovery system and/or premature failure of the after-filter system. The powder coating system  270  addresses this problem in conventional systems by using methods to cool the process air as it travels through the powder recovery system  74 , as described below. 
     The powder recovery system  274  may be used to recover powder overspray entrained in process air during and/or after a coating operation. The powder recovery system  274  includes a cyclone  282  (see  FIG. 18 ). While the cyclone  282  that is illustrated is a twin or double cyclone design, one or ordinary skill in the art would appreciate that other cyclone designs may be used, such as, a single cyclone design. The cyclone  282  comprises a cyclone body  298 . The cyclone body  298  includes a powder inlet  288 , which is in fluid communication with the suction duct outlet  146  of the suction duct  84 . The suction duct  84  provides a flow path for the process air entrained with powder overspray to travel from the spray booth  72  into the powder recovery system  274 . The powder recovery system  274  further includes an exhaust outlet  292 , which connects to the blower and after filter system. The exhaust outlet  292  of the cyclone  282  receives the process air from the cyclone  282  after most of the entrained powder has been removed via the vortical flow that is induced within the cyclone  282  (see  FIG. 12 , vortex  36 ). 
     As depicted in  FIGS. 16-18 , an enclosure  290  encloses at least a portion of the cyclone  282 . The enclosure  290  may be an outer jacket or shell  296  that is supported on a frame  294 . The jacket  296  may include a series of panels  204  that are fastened together, for example, using mechanical screws, bolts, or the like. In certain aspects of the disclosure, the panels  204  may also be welded together or held together using adhesives, or the like. The enclosure  290  may provide an enclosed space for a cooling medium  206  such as air. The cooling medium  206  may be used to cool one or more interior surfaces  208  of the cyclone  282 . Depending on the cooling energy needed to reduce the temperature of the cyclone interior surfaces  208  to a desired temperature, the cooling medium  206  may consist of ambient air (e.g., air taken from the nearby environment) or refrigerated air. The refrigerated air may be chilled using a commercial air conditioning unit or other cooling type unit. 
     The enclosure  290  may include an inlet  210  and an outlet  212 . The inlet  210  may be connected to a first conduit  211  for supplying the cooling medium  206  into the enclosed space defined by the enclosure  290 , and the outlet  212  may be connected to a second conduit  213  for receiving return air from the space defined by the enclosure  290  and passing the air back to a cooling unit to be cooled again for re-introduction into the enclosure  290  or to a disposal unit for releasing the air back to the outside. The first conduit  211  and the second conduit  213  may be connected to one or more fans (not depicted) that direct the air into and out of the enclosed space defined by the enclosure  290 . In certain applications, the first conduit  211  and the second conduit  213  may have 8 inch diameters. In certain applications, the first conduit  211  and the second conduit  213  may be located at distant locations to maximize flow through the enclosure  290  for contact and thermal exchange with as much surface area of an exterior surface  216  of the cyclone body  298 . 
     The powder recovery system  274  further includes a divider wall  218  to provide support for the cyclone  282 . The divider wall  218  may be positioned at a point along the length of the cyclone  282 . The divider wall  218  may include one or more openings  220  (see  FIG. 18 ) for allowing the cooling medium  206  to travel from a top portion of the enclosure  290  into the bottom portion. As such, the cooling medium  206  may enter the enclosure  290  from the inlet  210 , as represented by an arrow  214  in  FIG. 18 , and exit the enclosure  290  from the outlet  212 , as represented by an arrow  215  in  FIG. 18 . 
     In certain aspects of the disclosure, the jacket  296  of the may form a fluid-tight enclosure that at least partially surrounds the cyclone body  298 . In such aspects, the panels  204  of the jacket  296  may be welded together to prevent leakage of the cooling medium  206  out of the enclosed space defined within the jacket  296 . Nonetheless, it may be costly to form the jacket  296  in a fluid-tight manner. Thus, in other aspects, the jacket  296 , while decreasing the amount of cooling medium  206  that may escape from the jacket  296  to the surrounding environment, may not form a fluid-tight enclosure. For example, when the cooling medium  206  is air, it may not be necessary to form the jacket  296  so as to provide a fluid-tight seal. While a small amount of air may escape from the jacket  296  to the surrounding environment, a majority of the air would be held within the jacket  296  and serve the purpose of cooling the cyclone body  298 . 
     As noted above with respect to the embodiment of the powder recovery system  274  depicted in  FIGS. 1-15 , reducing the temperature of at least a portion of the cyclone body  298  may help reduce impact fusion of powder coating material within the cyclone  282 . In an aspect of the disclosure, the cooling medium  206  flowing through the enclosure  90  (e.g., air moving through the enclosure  90 ) may contact the exterior surface  216  of the cyclone body  298 , thereby being in thermal or heat exchange with the exterior surface  216  the cyclone body  298 . This thermal exchange will reduce a temperature of the interior surface  208  of the cyclone  282 . The temperature of the interior surfaces  208  of the cyclone  298  will depend in part on the thermal conductivity between the exterior surfaces  216  and the interior surfaces  208  of the cyclone body  298 . As such, a material such as stainless steel sheet metal or another material with high thermal conductivity may be used to form the cyclone body  298 . In certain aspects of the disclosure, the enclosure  90  may also be formed of an insulating material so that cooling energy from the cooling medium  206  is mostly absorbed by the cyclone body  298 . 
     While a single inlet  210  and a single outlet  212  are depicted in  FIGS. 16-18 , one of ordinary skill in the art would appreciate that more than one inlet and outlet may be disposed at various locations along the enclosure  290 . The dimensions of the enclosure  290  and volume capacity will in part be determined by the cyclone dimensions, as well as the volume and flow rate of cooling medium  206  needed to provide the desired temperature reduction of the interior surface  208  of the cyclone. 
     In some aspects, the cooling medium  206  may be a gas such as, for example, ambient or refrigerated air. Using a gas as the cooling medium  206  may reduce the costs associated with cooling the cyclone  282 . When oxygen or another common atmospheric gas is used, it may not be necessary to ensure that the gas does not escape to an exterior of the enclosure  290  when the gas is being used to cool the cyclone  282 . For example, if ambient air (or ambient air that has been cooled) is used, even if a small portion of the air escapes to an exterior of the enclosure  290 , the air would not pose any safety or operational risks. As such, it may not be necessary to ensure that the enclosure  290  provides a fluid-tight seal, thereby reducing manufacturing and maintenance costs. In contrast, when the cooling medium  206  is a liquid, it may be necessary to ensure that the enclosure  290  provides a fluid-tight seal in order to prevent leakage of the liquid onto the factory floor and/or surrounding machinery. Further, when ambient air (or ambient air that has been cooled) is used as the cooling medium  206 , the air may be easily disposed of after it has been used. 
     For example, the air may be passed through a filter and released back into the surrounding environment. In contrast, when the cooling medium  206  is a liquid, it may be necessary to connect the system to a drainage source to dispose of the used liquid. But a drainage source may not be available at certain work sites, and where a drainage source is not available, it may be necessary to store the liquid in large receptacles and/or keep the liquid in a closed loop whereby it is recycled back through the powder recovery system  274 . In such instances, it may become necessary to use a cooling unit to cool the liquid in between one or more uses; however, such cooling systems may be costly and require a large amount of space. Moreover, it may be preferable to use a gas as the cooling medium  206  such that a large volume of gas may be easily passed through the enclosure  290 , further increasing the cooling effects of the overall system. 
     Furthermore, systems and methods disclosed herein may be designed to provide a limited amount of cooling to powder entrained air. For example, in certain applications, it may be desirable to only cool the powder entrained air by approximately 10° F. 
     The many features and advantages of the disclosure are apparent from the detailed specification, and, thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and, accordingly, all suitable modifications and equivalents may be resorted to that fall within the scope of the invention. The various features and processes described above may be used independently of one another, or may be combined in various ways. All possible combinations and sub-combinations are intended to fall within the scope of this disclosure.