Separation device for coating blasting and coating stripping booths

A blasting or stripping booth is provided creating a generally downward flow for treatment of fluid and particle flow, which reduces operator exposure to potentially hazardous debris. The booth comprises an enclosure defining an upper region for a workpiece, a lower region, and a separator assembly. In some instances the separator assembly includes individual separator units which are discrete units, each having a generally square or rectangular plan view configuration which are arranged in an array for providing the required process flow capabilities. Further embodiments utilize structures forming the separator which have an elongated trough-like configuration. These embodiments find a particular application in large-scale stripping or blasting booth used in production environments where workpieces may flow through a treatment system in a serial manner. Other suitable applications include batch type processing of parts.

FIELD OF THE INVENTION

This invention relates to a separation device that may be used to separate blasting media from air and waste material for use in coating/blasting and coating/stripping booths.

BACKGROUND AND SUMMARY OF THE INVENTION

In some commercial and industrial operations it is necessary to treat products to remove surface finishes, clean surfaces, and strip off corrosion layers. In some instances, such processes are provided with newly manufactured components to properly finish surfaces for subsequent process steps such as painting, corrosion coating, plating, etc., which are collectively referred to here as blasting operations. In other instances, products which have been in service or were subjected to exposure or aging require surface coatings or corrosion to be removed such as rust and other forms of oxidation for further processing steps, referred to as a stripping operation. Such processes may be carried out in an open environment or in an enclosed blasting or stripping booth. Normally a high velocity stream of air is used having entrained blasting media which is directed to impinge on the workpiece surfaces. For enclosed processes, after the workpiece is treated it is usually necessary to separate the blasting media which may be of various types such as sand, beads, polymer bits, nut shells and various other materials referred to generally here as beads from air and the material removed from the part being processed which may include coating flakes, dirt, corrosion particles etc. collectively referred to as debris. So that the media can be recovered for reuse, a separation system is utilized. Ideally the beads can be recirculated and the debris can be separated for disposal. These systems can be used for blasting and stripping operations.

The present invention is related to a separation device for use in the above referenced applications.

SUMMARY

In accordance with the present invention, a number of embodiments of separator assemblies are disclosed which essentially create a generally downward stream of a mixture of air, debris and beads constituting a high solids concentration stream, which passes through a restricted flow area lower aperture. A secondary flow path is provided in which a flow stream moves in an upward direction, around a baffle, cone or hat structure to pass into a downwardly extending stream having a low concentration of entrained solids. The high solids concentration stream can be passed through downstream separation devices to reclaim beads and separate debris. Preferably the beads can be reused in a continuous closed-loop process. The low solids concentration stream can also be subjected to further downstream treatment such as using particulate filters or other separation devices to produce a stream of cleaned air with debris trapped for disposal or recycling. Booths in accordance with the present invention, by providing the generally downward flow through the treatment area provide distinct benefits over prior art booths in which the airflow has a substantial horizontal component. The generally downward flow and the treatment of the entirety of the fluid and particle flow through the booth reduces operator exposure to potentially hazardous debris.

Various embodiments of the invention are disclosed. In some instances the separator assembly includes individual separator units which are discrete units, each having a generally square or rectangular plan view configuration which are arranged in an array for providing the required process flow capabilities. Further embodiments utilize structures forming the separator which have an elongated trough-like configuration. These embodiments find a particular application in large-scale stripping or blasting booth used in production environments where workpieces may flow through a treatment system in a serial manner. Other suitable applications include batch type processing of parts.

DETAILED DESCRIPTION OF THE INVENTION

The invention will now be described with reference to the Figures.FIGS.1a, bandcillustrate blasting or stripping booth10in accordance with the first embodiment which is provided as a generally rectangular cuboid enclosure11with an upper region12in which an article to be blasted (not shown) may be placed. An internally or externally manually operated blasting gun may be used to present a high velocity stream of air and blasting media (or generally “beads”) against the workpiece being processed. In other applications, robotic systems are used to move a blasting nozzle to direct the blasting/stripping stream in a desired manner. Enclosure11is closed on all sides to create a controlled environment for treating the workpiece.

The lower region14of blasting or stripping booth10includes separator assembly16constructed in accordance with an embodiment of the present invention. In a commercial embodiment of booth10a grate or other structure would be provided in booth upper region12to support the workpiece, the operator and associated equipment. Such a grate (not shown) would be perforated to permit air and particle flow in a generally downward direction from the booth upper region12through the grate and into separator assembly16.

Separator assembly16is further illustrated byFIGS.2a, bandcin more detail. Separator assembly16forms a generally rectangular cuboid outer surface including side walls18,20,22and23, which are enclosed by bottom wall24. Separator assembly16forms an array of generally vertical separator elements26arranged in an egg carton like 3×3 array, this being one example. Other array configurations (M×N) could be provided to accommodate any required area. The cross-sectional views through these separator elements26are provided with reference toFIGS.1aand1b. Each of the separator elements26shown for separator assembly16have a generally common configuration.

Referring to a single separator element26shown inFIG.3, each includes surrounding funnel wall28forming a converging cross-sectional area, for flow moving vertically downward. Funnel wall upper inlets30are each arranged to join at edges32bounding adjacent separator elements26, or one of the side or end walls18-23. Funnel wall28converges to lower aperture34at its lower end. Vertically extending concentrically within aperture34is a partition in the form of pipe36, having upper and lower open ends,37and39respectively. Baffle38is positioned over pipe upper end37but is spaced from the pipe upper end to provide a flow passage under the baffle and into the pipe upper end37. Lower aperture34is partly obstructed by the passage of pipe36, but forms a generally annular passageway41. For a number of embodiments described herein baffle38can be provided in various forms such as a hat structure, a cone, or a cover or any other structure which prevents the direct impingement of incoming flow into pipe upper end37. These alternate forms are collectively referred to as a baffle.

Referring again toFIGS.1a-c, partition wall40divides separator assembly16into an upper chamber42and lower chamber44. Pipe36extends down into lower chamber44, penetrating through or opening on the surface of wall40. Lower chamber44communicates with separator air outlet46. The upper chamber44above wall40is a plenum for separator air/solids outlet48.

In describing the operation of separator assembly16, reference is made to blasting media which may be of various types such as those mentioned previously, generally referred to as “beads”. The beads, when contacting the workpiece, generate flakes or other particles of various sizes which are released by the workpiece, referred to here, generally as debris.

In operation of blasting or stripping booth10, airflow is provided in a generally downward direction through booth10passing through upper region12and into separator16. During the blasting or stripping operation, the beads impinge on the workpiece surface to be stripped or blasted, producing the debris. Accordingly, the downward flowing stream entering into separator assembly16is a mixture of air, beads, and debris. Separator assembly16is designed to provide a high solids concentration stream of beads and debris (referenced in the drawings as “HC”) exiting at air/solids outlet48, and a low solids concentration stream (referenced in the drawings as “LC”) exiting from separator air outlet46which can be treated to remove entrained particulates for discharge.

FIG.3provides an illustration of the operation of separator assembly16showing a single separator element26. In this illustration, beads are shown as small spheres, and debris is shown as oblong or ellipse shaped objects. Stream arrows illustrate the primary fluid flow directions of various streams within the separator element26. For some flow stream components, the air/beads/debris stream impinges directly onto funnel wall28and is directed downwardly between the funnel wall and the outside of pipe36into the open annular passageway41. This stream has a high concentration of solids (beads and debris). The flow stream of air/beads/debris stream segments which directly contact the upper surface of baffle38is deflected toward funnel wall28and is also concentrated into annular passageway41which forms an entry of a first passageway. Funnel wall28presents a decreasing flow area for the stream mixture so that the concentration of solids increases as the flow moves downwardly. Due to the relatively small flow area provided by annular passageway41and the high concentration of entrained solids, a high flow rate of air is restricted from flowing through the area. These flow passages communicate with upper chamber42for discharge through air/solids outlet48. This stream is subjected to further downstream treatment for the separation of beads from debris. Preferably, the beads can be reused in a recycling continuous manner.

FIG.3also illustrates another stream of flow paths following a more tortuous path, moving initially downwardly and then upwardly in the annular region surrounding baffle38to enter into pipe upper end37. This stream, due to the torturous flow path and the effects of gravity and inertia, once entering into baffle38, tends to have a much lower solids concentration and is referred to here is a low solids concentration stream. This stream enters into pipe upper end37and flows through the pipe forming a second passageway into lower chamber44. Flow from a number of separator elements26are joined together in lower chamber44for discharge from separator air outlet46. Since this discharge has a low concentration of solids, it can be treated using filters or subsequent particulate separating devices to allow the discharge of process air or the recirculation of the cleaned air back into the blasting zone or booth.

FIG.4shows the joining of multiple units of separator elements26which corresponds more closely to the illustrations ofFIGS.1a-cand2a-c. Each of the illustrated separator elements26operates in a manner consistent with that previously described with reference toFIG.3.

The funnel walls28of separator elements26are illustrated in this description as having an essentially inverted square base pyramidal shape. Many other configurations may be used, such as triangular based pyramids or conical shapes. The invention may be carried out with others such shapes and structures which present a decreasing flow area for the flow mixture as it travels downwardly through the separator unit.

In the above-described embodiments of separator assembly16, a number of discrete elements of the separator assembly are arranged in a rectangular array as previously explained. For these devices, baffles38are formed generally with rotational symmetry about a vertical axis passing through the pointed top of the cones and through the center of pipes36. An alternate embodiment of the present invention is described with reference toFIGS.5-7, referred to as separator assembly60. Unlike the first embodiment, separator assembly60includes a number of elements which have a cross-section stretched in a linear manner, which may correspond to the direction of a conveyor passing through blasting booth62. Other orientations are feasible such as perpendicular to the direction of the conveyor or other skewed relationships. Separator assembly60also differs from separator assembly16in that the first and second passageways for the high and low solids concentration streams respectively, rather than being concentric, are laterally displaced. In this case, the lower aperture of funnel wall70is not obstructed by a partition but instead a portion of the funnel wall laterally displaced from the lower aperture forms the partition for the second flow passageway for the low solids concentration stream. The funnel wall sections of adjacent separator elements joined together to form the second passageway, as best shown with reference toFIG.5.

Referring particularly toFIG.5, the airflow and particle flow of the alternate embodiment of a separator assembly60is shown.FIGS.5-7show only the separator assembly60and not the upper region12of the booth. Referring toFIGS.6and7, a number of separator assemblies60are also arranged generally in a rectangular array configuration.FIG.6is a side view of an array of separator assemblies60showing that the separate separator assemblies are arranged in a linear manner along a conveyor direction shown in the figure. Reference here is made to a conveyor since this embodiment is especially well suited for industrial applications incorporating an elongated blasting or stripping booth through which parts are conveyed in a serial manner.FIG.7is a front view showing a number of separator assemblies60arranged to join laterally.

For separator assembly60, rather than a conical shaped baffles as in the first embodiment, elongated baffles64are provided. Baffles64cover a narrow slot66formed by closely spaced walls forming channel68. Adjacent to slot66, funnel walls70are provided which converge to lower slot72formed by closely spaced parallel walls74. Funnel walls70of adjacent separator elements meet to form the upwardly facing extending slot66. As best shown inFIG.6, slot72and walls74form a first passageway which converges to meet at solids pipe78. With this configuration, a mixture with a high concentration of solids is directed to collect into slot72and is then directed to flow into air/solids pipe82. Slot66which is an entrance of a second passageway is formed at adjoining funnel walls70of funnel walls which are stretched along a line.

Separator assembly60operates in a manner similar to that of separator assembly16. As shown inFIGS.6and7, a plurality of individual separator assemblies60are arranged as shown. As mentioned previously, the upper portion of booth10is not shown by these figures. In addition to the elongated configuration of separator assembly60, another difference with the first embodiment is evident inFIG.5which shows that the vertical axes of the flow of high and low concentration streams are laterally offset rather than in a coaxial arrangement as in the first embodiment. As shown inFIG.5, the mixture with high solids concentration becomes collected within funnel walls70which converge at slot72forming the first passageway and later are collected from pipes78through a manifold arrangement shown inFIG.7into a collector solids pipe82. Referring again toFIG.5, a low concentration mixture is provided by the tortuous flow pattern required for the fluid/solids mixture to flow initially downwardly from the upper region of blasting booth68, to flow into the region of funnel walls70and then turn direction to move upwardly between the gap formed between baffles64and the upstanding walls of slot66. The low concentration mixture that flows downwardly through slot66forming the second passageway and is collected in a plenum connected with adjoining separator elements and is directed to a separator air outlet (not shown) for further processing. This embodiment of separator assembly60also differs from the first embodiment in that rather than relying on a partition wall in the lower region of the booth to separate the high and low concentration mixtures, this separator assembly directs the high concentration mixture into pipes78and82.

Referring toFIG.8, a further modified version of separator assembly60is shown, referred to as separator assembly90. The difference with this embodiment is that the troughs80formed by pairs of funnel walls70meet at an edge76, rather than forming slot66. Depending on applications, this version may be well suited for some applications without requiring the provision of a baffle64at every junction between adjacent pairs of troughs80.

The embodiment of separator assemblies60and90in accordance with the second embodiment are well adapted for industrial operations involving a linearly moving a conveyor since that is well suited for an elongated configuration. Moreover, there may be fabrication cost advantages for separator assembly60with elongated components have been a constant cross-section rather than using tubular parts such as pipes.

In the case of separator assemblies60and90as shown by the figures structural beam elements84are shown for supporting the separator units and associated structure. Structural elements84also support equipment, operators, workpieces and a support grating, etc.

FIG.9illustrates a still further embodiment of the present invention. This embodiment of separator assembly86utilizes elements from the prior embodiments, which are identified by like reference numbers. Separator assembly86uses a grate like plate88forming separator walls20-23dividing discrete separator units92. The lower surface of baffles88form funnel walls28with a concentric pipe36extending therethrough. Baffles38are positioned over the pipe upper end37. As in prior embodiments, two distinct flow paths are provided. A high solids concentration mixture falls through annular passageway41and into upper chamber42. In this case, upper chamber42is formed by a separator plate94. A low solids concentration stream flows upward into and down through pipes36into a lower plenum area.

A still further embodiment of separator assembly96is shown inFIG.10. Separator assembly96is very similar to the design illustrated inFIG.8. In this alternate configuration of separator assemblies16and90the various pipe elements may be replaced by passageways formed by sheet metal elements to provide the same function as pipes. Such embodiments are described in the following description. The embodiment ofFIG.10also illustrates attachment brackets98which support baffle64. Adjustment brackets98permit the position of baffle64relative to the upper edge of slot66to be adjusted. This will have the effect of changing the flow restrictions of the second passageway for the low solids concentration stream. This will enable a balancing of the flow rates for the high and low concentration streams to be provided. Other mechanisms and attachments for the baffles described throughout this description may be provided for a similar balancing adjustment. Here, elongated baffles64are placed over sheet metal elements forming slot66. The high solids air/particle mixture is transmitted in this case through pipes78and82. This figure provides a conceptual model of the operation of the device equivalent to that previously described.

InFIG.10funnel wall70is shown having surfaces formed of planar segments joining together along break lines with differing angles. Alternate configurations can have a funnel wall with a surface forming a single planar angle or curved surfaces may be used as desired.

FIG.11provides an embodiment of separator assembly100equivalent in operation to separator assembly96, except in this case, the functions of pipes78and82are provided by sheet metal ducts including panel102which together with other associated panel structures form a conduit for the flow of the high solids fluid mixture.

FIG.12provides a flow schematic of the use of any of the separator elements previously described in a stripping or blasting system.FIG.12illustrates the flow of fluids and solids to the system and illustrates a closed loop reclamation system for the beads and a system for consolidating debris for rejection and disposal. As shown overall airflow is driven by fan104. The low concentration stream flows through filter106. The high concentration stream is first directed to settling tank108and then to classification device110. From classification device110there is a reject flow and a recycle flow shown being directed back to booth10. These latter components part of a reclaim system enclosed by the dotted lines in the figure. The reclaim schematics shown is for illustration purposes, other methods can be used to separate debris from beads such as cyclones, fluidized beds, sieves, etc. The present invention should is not limited by the method used to separate the debris from the recycled/reclaimed beads.

FIGS.13and14provide pictorial depictions of separator assemblies104and106showing features similar to prior embodiments which shares the feature of separator assembly100in that separate pipe type fluid flow elements are eliminated in favor of ducts formed from sheet metal components. The difference betweenFIGS.13and14is the direction of the high concentration and low concentration airflows. InFIG.13, they run perpendicular to the lengthwise symmetry of the device, while inFIG.14these airflows run parallel to the lengthwise symmetry of the device. This highlights a good balance between simplicity of the device and flexibility in the arrangement of its components which helps adapting it to different application scenarios.

For any of the described embodiments it is necessary to design the flow areas for the fluid stream areas of the first and second passageways to provide a proper flow rate balance between the high and low solids concentration streams. An example of such design considerations is described with reference to the first embodiment. The flow stream through booth10is driven by a pressure differential between upper region12and the lower region14of blasting booth10. The flow area through the annular passageway41in the first embodiment must not permit a free flow of the untreated stream through the device exiting through the annular passageway, which would result in poor separation efficiency. Instead the annular passageway flow area needs to be restricted to develop sufficient pressure differential to drive a secondary flow stream described previously which will move initially downwardly and then upwardly around baffle38, which becomes the low solids concentration stream. If flow restrictions for the high solids concentration stream is too great, this flow path will essentially become “plugged” which will drive an excess flow rate through the inside of pipe36and the low solids concentration stream will have an excess solids concentration. This balancing principle it is applicable in each of the embodiments described previously. The precise relationships of flow areas and flow configurations are dependent upon numerous factors including beads and debris concentration flow rate requirements installation constraints etc. and cannot be defined here for every application. One mechanism for providing the balancing is mentioned previously with adjustments of baffle position which can influence the flow restrictions through the second passageway.