GB2486703A

GB2486703A - Spray booth ventilation system with nozzles for blowing air transverse the main airflow

Info

Publication number: GB2486703A
Application number: GB1021823.8A
Authority: GB
Inventors: Michael Williams
Original assignee: Spraybooth Technology Ltd
Current assignee: Spraybooth Technology Ltd
Priority date: 2010-12-23
Filing date: 2010-12-23
Publication date: 2012-06-27
Anticipated expiration: 2030-12-23
Also published as: GB201021823D0; GB2486703B

Abstract

A spray booth 100 comprises a roof portion, first and second end portions, 102, 104 and first and second side portions 103, 105 together defining a work space having a longitudinal axis, an air input region 106 adjacent the first end portion and arranged for introducing a substantially uniform air flow 120 into the workspace parallel to the longitudinal axis, an air extraction aperture 128 defined at the second end, air input ducting 110 located adjacent the roof portion for transferring air from air handling equipment to the air input region 106, wherein at least one air injector / vent 112, 114 receives air from the ducting and provides an air jet 122, 124 transverse to said longitudinal axis (i.e. perpendicular to main airflow). With nozzles injecting air at various positions along the booth length, air saturation during drying can be reduced. This booth is envisaged for long items such as aircraft and wind turbine tower sections. Figure shows top view.

Description

SPRAY BOOTHS

The present invention relates to spray booths.

BACKGROUND OF THE INVENTION

A spray booth is a structure that provides a ventilated, air filtered and temperature controlled environment in which spraying activities such as painting and powder coating can take place. A spray booth is necessary for the safe execution of such activities, since the sprayed materials include solvents and particulate material that must not enter the atmosphere in large quantities. The particulate material that does not stick to the article being sprayed must be removed from the spraying area to ensure safe working conditions, and to manage environmental impact.

A spray booth also provides a controlled supply of filtered air that aids the spraying process and leads to higher quality finishes. In addition, it is necessary to heat sprayed materials in order to dry them (in a process known as baking), and the spray booth provides a controlled temperature environment in which such baking can be undertaken.

Spray booths are used in the wind turbine industry during the painting and finishing processes for sections of wind turbine towers. Since the tower sections can be many metres in length, the booth tends to be a long, relatively narrow design.

By way of example and explanation, one known tower spray booth is illustrated in Figure lof the accompanying drawings. The spray booth 1 comprises a roof portion 10 from which first and second end portions 12, 14 and first and second side portions 13, 15 extend to the ground, thereby forming a closed chamber, or work space, in which spraying can be carried out. The first end portion incorporates a closable access way (not shown for clarity) through which the tower sections (or other items to be sprayed) can enter and exit the work space.

A plenum 16 is formed adjacent an end region of the roof portion 10 by the provision of a filter element 18 substantially parallel to, and spaced from the inner surface of the end region of the roof portion 10. The plenum 16 may extend any desired distance along the roof portion 10 from the first end 12 to wars the second end 14 of the booth 1. The filter element 18 may extend across the whole of the roof portion 10, as illustrated, or may be provided across only a limited width. As will be described in more detail below, an input air flow 20 is supplied into the plenum 16, after which it passes through the filter 18 and forms an incoming air flow 22. Ideally the air flow 22 is uniform across the width of the booth.

The airflow 21 passes along the booth 1, and forms an outgoing air flow 24. This outgoing airflow 24 passes through an outgoing filter 23, into an extraction region 22, which provides an extracted airflow 42.

The input airflow 20 is provided by air handling equipment, such as that shown for illustrative purposes in Figure 2 of the accompanying drawings. The air handling equipment 26 of Figure 2 comprises input ducting 30 which guides air 28 into the equipment from the atmosphere. A fan unit 32 is provided for drawing in the air 28, and for moving the air via ducting 34 to a heater 36 which operates to heat the air to a desired temperature. The temperature controlled air 20 is then provided to the plenum 16 of the spray booth I via ducting 38.

Air extraction from the booth I is provided by air extraction equipment 40, such as that shown for illustrative purposes in Figure 3 of the accompanying drawings. The outgoing airflow 24 is drawn through ducting 44 by an extraction fan unit 46. The airflow passes through a further filtration unit 50 before exiting to atmosphere as the extracted airflow 42 via further ducting 52.

Figures 4 and 5 of the accompanying drawings illustrate plan and side views respectively of the booth I of Figure 1, showing the airflow therein. Air 20 is provided into the plenum 16 from which is exits as a filtered uniform airflow 21. The airflow 21 travels along the length of the booth I from the plenum 16 towards the second end 14 of the booth 1, forming a uniform outgoing airflow 24. The airflow 24 passes through the exit filter 23, and into the extraction region 22 for exit from the booth as an extracted airflow 42.

The spray booth I of Figure 1 and the air handling equipment 26, 40 of Figures 2 and 3 has been described by way of example and illustration only, and it will be readily appreciated that the design and construction of a spray booth can vary. For example, the input and output air handling equipment can be combined to reduce the number of fan units and reduce the heating requirements by using recirculation of air.

It will also be appreciated that the principles of the spray booth described above can be applied to a booth for the spraying of aircraft, or other large items other than wind turbine tower sections. Naturally, the specific design requirements of each application will determine the size and specification of the spray booth and the equipment, but the principles remain the same as for the booth described above.

Existing spray booth designs suitable for providing spraying environments for large items, particularly long items, suffer from a drawback that drying of the sprayed coating can take a significant amount of time due to the cooling characteristics of the airflows provided.

Figures 6 and 7 illustrate the airflow end and partial plan views respectively of a wind turbine tower section 3 located in a spray booth 1, such as that described above. The tower section 3 is carried on a support 5 by rotatable members 4 which operate to rotate the tower section 3 during the spraying operation, as indicated by arrow 6. As shown in Figure 7, the airflow 21 from the plenum 16 passes along and through the tower section 3. The airflow along the tower section 3 is ideally a uniform flow 58 without any significant turbulence. This lack of turbulence is important during the spraying operations in order to minimise coating flaws and contamination. Turbulence can lead to particles being picked up from the floor, and overspray, being deposited on the tower section 3 being sprayed. In addition, the uniform turbulence-free airflow 58 serves to remove overspray in a quick and clean manner.

The airflow exits the booth, as described above, through an exit filter 23 and an extraction region 22.

Whilst the provision of a uniform airflow 58 along the tower section 3 is essential for high quality results during the spraying operation, such a flow has significant drawbacks when the process moves to the drying operation. In order for the coating applied to the tower section 3 to dry correctly, it is necessary to raise the temperature of the air inside the booth, so that the solvents in the coating evaporate from the surface, thereby drying the coating. With the airflow 58 as shown in Figure 7, a saturated layer of air builds up along the surface of the tower section. This saturated layer means that the tower section 3 dries slowly from its end closest to the plenum, and that the other end takes an undesirably extended time to dry, since it is necessary for an unsaturated air flow to reach the surface in order for it to dry. In addition, the length of the tower section 3 means that the air flow loses a significant amount of heat as it flows along the section. Only as the tower section heats up does the temperature of the air remain at the required level further along the section. This heat loss from the air means that the drying operation consumes a very large amount of energy, which is undesirable.

It is, therefore, desirable to provide a solution to such drawbacks.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is provided a spray booth for providing a controlled environment for spraying of material, a spray booth for providing a controlled environment for spraying of material, the spray booth comprising a roof portion, first and second end portions which extend from respective opposing ends of the roof portion, first and second side portions which extend from respective opposing sides of the roof portion, thereby defining a work space between the roof portion, the end portions and the side portions, the work space having a longitudinal axis, an air input region adjacent the first end portion of the booth, and arranged for introduction of a substantially uniform air flow into the work space, substantially parallel to the longitudinal axis of the work space, an air extraction aperture defined in the second end portion, the air extraction aperture being arranged for extraction of air out of the work space, air input ducting located adjacent the roof portion, and arranged to transfer air from input air handling equipment to the air input region, and at least one air injector arranged to receive air from the air input ducting, and operable to provide an air jet into the work space, which air jet has a direction substantially transverse to the longitudinal axis of the work space.

In one example, the air input ducting has first and second portions which extend adjacent the first and second sides of the booth respectively, the first and second portions of the air input ducting having respective pluralities of such air injectors mounted thereon.

Such air input ducting may be provided by ducting having a closed boundary forming a substantially regular cross section. Alternatively, each of the first and second portions of the air input ducting may be formed by a region of the roof portion, a region of the corresponding side portion, and sheet material extending between roof portion and that side portion, thereby defining a duct therebetween, and wherein the sheet material has a plurality of such air injectors mounted thereon.

Such a spray booth may further comprise an input filter in the air input ducting and/or in the air input region.

Such a spray booth may also comprise an exit filter that extends across the air extraction aperture.

Such a spray booth may further comprise a controller for controlling the or each air injector.

According to a second aspect of the present invention, there is provided a spray booth installation comprising a spray booth according to the first aspect of the present invention, input air handling equipment operable to provide an input air flow to the air input ducting, and output air handling equipment operable to extract air from the air extraction region.

The input air handling equipment preferably includes a heater unit operable to heat such an airflow to a desired temperature.

In one example, such a spray booth is arranged for receiving a section of a wind turbine tower in the work space.

According to a third aspect of the present invention, there is provided a kit of parts for a spray booth in accordance with the first aspect of the present invention.

According to a fourth aspect of the present invention, there is provided a kit of parts for a spray booth installation in accordance with the second aspect of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 illustrates a known spray booth; Figures 2 and 3 illustrate known air handling equipment for the spray booth of Figure 1; Figures 4 and 5 illustrate plan and side views respectively of the booth of Figure 1, showing airflow therein; Figures 6 and 7 illustrate end and plan views respectively of a wind turbine tower section located in a spray booth; Figure 8 illustrates a plan view of a spray booth embodying the present invention; and Figure 9 illustrates an end view of a spray booth embodying the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Figure 8 illustrates a plan view of a spray booth 100 embodying the present invention, which is similar construction to the booth described above. A roof portion (not shown), first and second end portions 102 and 104, and first and second side portions 103 and 105 form an enclosed work space. A plenum 106 is provided adjacent one end region of the roof portion, and serves to direct an incoming airflow 120 into and along the length of the booth 100. An extraction area 120 is provided into which air 126 from the work space is drawn, through an exit filter 121. The extracted air is exhausted from the booth as exhaust airflow 128. This uniform airflow 120, 126 is provided as described above during the spraying operation, and provides a filtered air stream that removes overspray away from the object being sprayed.

The booth 100 embodying the present invention includes at least one air inlet 108 (two are shown in Figure 8, but any number can be provided). In the example shown in Figure 8, each air inlet is positioned towards the second end of the booth, adjacent the extraction region 120 and exit filter 121. The positioning of the air inlets is a matter of design, and will vary for specific requirements of booth, whilst remaining in accordance with the principles of the present invention.

Each air inlet 108 receives are air supply 109 from input air handling equipment, and is connected to an inlet duct 110 which extends along the length of the booth to the plenum 106. The ducting 110 transfers air 109 from the air inlet 108 to the plenum 106 for input into the booth as airflow 120. Each length of ducting 110 is provided with a number of air outlets.

In the example shown in Figure 8, each length of ducting 110 has first and second air outlets 112 and 114. The air outlets 112 and 114 are arranged to direct air 122 and 124 from the ducting 110 into the booth 100 in directions substantially transverse to the airflow 120 input from the plenum 1 06. In this way, a turbulent air stream can be created in order to aid and speed up the drying operations.

Each air outlet 112, 114 is controlled individually, so that the desired turbulent air flow and temperature profile can be created in the booth 100. Each air outlet 112, 114 has an air control valve which is operable to control the amount of airflow ejected from the outlet.

Preferably, the control valve is continuously variable from completely closed to completely open, but may operate in a predetermined number of steps. One example of a control valve is simply a flap that swings across the ducting to redirect airflow from the ducting 110 into the air outlet 108, so that air exits the air outlet 112, 114.

Figure 9 illustrates an end view of a spray booth embodying the present invention, in which a wind turbine tower section 3 is in place on the rotatable support 4, 5, as described above.

The booth 100 of Figure 9 includes the air inlets 108 connected to receive inlet airflows I 09, and to transfer that airflow to ducting 110. The inlet airflow 109 is provided by the input air handling equipment, and so is heated to the desired temperature. Preferably, the input air handling equipment includes a filter section.

In the Figure 9 example, the ducting 110 is provided a sheet material 111 arranged across the upper corner of the booth. It will be appreciated that the ducting could alternatively be provided by conventional ducting of square or rectangular section. The ducting 110 extends from the inlet to the plenum 106.

In the example shown in Figure 9,the air outlets 112, 114 are provided by nozzles 113 which extend from the sheet material 111. The nozzles are shaped so as to produce high speed air jets 130 which travel substantially transverse to the airflow 120 in the booth, towards the item located in the booth.

The high speed air jets 130 cause a turbulent airflow pattern 132 to be created inside the booth. The turbulence serves to present an ever changing air flow to the surface of the tower section, such that the surface is encouraged to dry more quickly than in the previously-considered booth. The resulting decreased drying time enables a greater throughput of tower sections through the booth, leading to increased productivity, and also reduces the amount of energy required to heat the air in the booth.

The reduction in required heating energy is achieved by the effective mixing of the heated air with the air in the booth. By injecting heated air at intervals along the booth, it is possible to create an even temperature distribution along the length of the tower section. This temperature distribution enables significant time savings to be made. In one example, the drying time for a tower section can be reduced from eight hours to four hours, which can result in a near doubling of productivity of the spray booth.

Although aspects of the invention have been described with reference to the embodiment shown in the accompanying drawings, it is to be understood that the invention is not limited to the precise embodiment shown and that various changes and modifications may be effected without further inventive skill and effort.

Claims

SCLAIMS: 1. A spray booth for providing a controlled environment for spraying of material, the spray booth comprising: a roof portion; first and second end portions which extend from respective opposing ends of the roof portion; first and second side portions which extend from respective opposing sides of the roof portion, thereby defining a work space between the roof portion, the end portions and the side portions, the work space having a longitudinal axis; an air input region adjacent the first end portion of the booth, and arranged for introduction of a substantially uniform air flow into the work space, substantially parallel to the longitudinal axis of the work space; an air extraction aperture defined in the second end portion, the air extraction aperture being arranged for extraction of air out of the work space; air input ducting located adjacent the roof portion, and arranged to transfer air from input air handling equipment to the air input region; and at least one air injector arranged to receive air from the air input ducting, and operable to provide an air jet into the work space, which air jet has a direction substantially transverse to the longitudinal axis of the work space.
2. A spray booth as claimed in claim 1, wherein the air input ducting has first and second portions which extend adjacent the first and second sides of the booth respectively, the first and second portions of the air input ducting having respective pluralities of such air injectors mounted thereon.
3. A spray booth as claimed in claim 2, wherein the air input ducting is provided by ducting having a closed boundary forming a substantially regular cross section.
4. A spray booth as claimed in claim 2, wherein each of the first and second portions of the air input ducting is formed by a region of the roof portion, a region of the corresponding side portion, and sheet material extending between roof portion and that side portion, thereby defining a duct therebetween, and wherein the sheet material has a plurality of such air injectors mounted thereon.
5. A spray booth as claimed in any one of the preceding claims, further comprising an input filter in the air input ducting and/or in the air input region.
6. A spray booth as claimed in any one of the preceding claims, comprising an exit filter that extends across the air extraction aperture.
7. A spray booth as claimed in any one of the preceding claims, further comprising a controller for controlling the or each air injector.
8. A spray booth installation comprising a spray booth as claimed in any one of the preceding claims, input air handling equipment operable to provide an input air flow to the air input ducting, and output air handling equipment operable to extract air from the air extraction region.
9. A spray booth installation as claimed in claim 8, wherein the input air handling equipment includes a heater unit operable to heat such an airflow to a desired temperature.
10. A spray booth installation as claimed in claim 8 or 9, arranged for receiving a section of a wind turbine tower in the work space.
11. A kit of parts for a spray booth as claimed in any one of claims 1 to 7.
12. A kit of parts for a spray booth installation as claimed in any one of claims 9 to 10.
13. A spray booth substantially as hereinbefore described with reference to, and as shown in, Figures 8 and 9 of the accompanying drawings.
14. A spray booth installation substantially as hereinbefore described with reference to, and as shown in, Figures 8 and 9 of the accompanying drawings.