Apparatus for Cleaning an Exhaust Gas Stream

Field of the Invention.

The present invention relates to an apparatus for cleaning an exhaust gas stream. In particular, the present invention related to an apparatus for removing particulates and gases from spray booths and the like.

Background Art.

In many industrial processes, exhaust gases become contaminated with particulate matter or toxic and environmentally-harmful gases that are often released into the atmosphere. These gases can pose significant environmental and health risks.

Spray booths, such as those used in spray painting or powder coating applications, generate exhaust gases that often contain particulates in the form of paint or powder particles. In addition, spray booth exhaust gases often contain volatile organic compounds (VOC) which need to be removed from the gas stream prior to releasing the exhaust gas to the atmosphere.

Existing exhaust filters suffer from the drawback that, while they may be used to remove VOC from an exhaust gas stream, they quickly become blocked with paint and other particles, leading to requiring regular cleaning and maintenance and therefore reducing their effectiveness.

Therefore, there would be an advantage if it were possible to provide an apparatus for cleaning an exhaust gas stream which could remove particulate matter and harmful gases from the exhaust gas stream, whilst having a lesser tendency to becoming blocked with particulates.

It will be clearly understood that, if a prior art publication is referred to herein, this reference does not constitute an admission that the publication forms part of the common general knowledge in the art in Australia or in any other country.

Throughout this specification, the term "comprising" and its grammatical equivalents

shall be taken to have an inclusive meaning unless the context of use indicates otherwise.

Object of the Invention. It is an object of the present invention to provide an apparatus for cleaning a gas stream which may overcome at least some of the abovementioned disadvantages, or provide a useful or commercial choice.

In one aspect of the invention, there is provided an apparatus for cleaning a gas stream, the apparatus comprising one or more inlets through which a gas stream can flow, particle removal means adapted to remove particles from said gas stream, particle collection means in which particles removed from the gas stream are collected and one or more outlets through which a cleaned gas stream can flow.

The skilled addressee will understand that the apparatus of the present invention may be adapted for use in a wide variety of industries and applications wherein hazardous gases (such as those containing VOC) are emitted through ducting, chimneys or any other form of directed air flow (for instance, printing, mining, meatworks, photographic developers, chemical plants, spray booths, manufacturing plants and so on).

Preferably, the apparatus is contained within a housing. The housing may be of any suitable size, shape and construction, however, it is preferred that the housing is constructed from a resilient material, such as metal, wood, plastic or the like.

In some embodiments of the invention, the housing may be provided with one or more apertures therethrough. The one or more apertures may be used as the one or more inlets and one or more outlets through which the gas stream can flow. The one or more apertures may be of any shape, size or location within the housing. Preferably, however, at least one of the one or more inlets is provided in an upper surface of the housing. In this way, at least a portion of the gas stream entering the apparatus may be directed downwards as it enters the apparatus.

In a preferred embodiment of the present invention, the one or more inlets and/or the one or more outlets through which a gas stream can flow may comprise filtration means. Preferably, the filtration means is adapted to remove particles and/or gases from the gas stream. The filtration means may comprise any suitable prior art filter or filter medium for removing particles and/or gases from the gas stream and the particular construction of the filtration means is not critical to the working of the present invention.

In some embodiments of the invention, one or more of the outlets may be provided with protection means for protecting the filtration means from damage, such as from the elements, accidental damage by users, and the like. Any suitable protection means may be used, although in a preferred embodiment of the invention, the protection means may comprise a cover. Preferably, the protection means is removable such that the protection means may be removed in order to gain access to the filtration means (such as for maintenance purposes or when replacement of the filtration means is required).

The protection means may be of any suitable shape, size or configuration, although it is preferred that the protection means is shaped so as to reduce or eliminate the likelihood of the ingress of water (for instance, when it is raining) through the outlets of the apparatus. In addition, the protection means may be shaped so as to direct the flow of the cleaned gas stream as it exits the apparatus through the outlet.

In some embodiments of the invention, the protection means may be adapted to assist in retaining the filtration means in place in the outlet of the apparatus. In this embodiment of the invention, the filtration means may be adapted for retention within the outlet and the protection means may simply hold the filtration means in place. Alternatively, the filtration means may be adapted to be retained within the protection means (for instance, within a frame or opening in the protection means), and the protection means may be located such that the filtration means is aligned with the outlet. In some embodiments of the invention, the filtration means may be formed integrally with the protection means or may be formed separately therefrom and attached thereto when in use.

The gas stream entering the apparatus through the one or more inlets may be directed towards the particle removal means. The gas stream may be directed towards the particle removal means using any suitable method, such as, but not limited to, funneling or channeling the gas stream through the apparatus, such as by using air diverters. The air diverters may be of any suitable form, although in some embodiments of the invention, the air diverters are in the form of one or more fixed or moveable plates which channel the gas stream through the apparatus towards the particle removal means. The air diverters may also be configured so as to increase the velocity of the gas flowing therethrough.

In some embodiments of the invention, the one or more inlets or the air diverters may be provided with one or more gas flow enhancement means. The gas flow enhancement means may comprise any suitable means adapted to speed up and direct the flow of gas onto the particle removal means. In one embodiment of the invention, the gas flow enhancement means comprises one or more reed valves. The one or more reed valves impart a "fluttering" effect to the gas stream, making the gas stream take an erratic flow path and diverting the gas stream onto the particle removal means.

The particle removal means of the present invention may comprise any suitable means adapted to assist in removing particulate matter from the gas stream as it passes through the apparatus. The particle removal means may achieve removal of particles from the gas stream by slowing, restricting or diverting (or a combination of two or more of these) the flow of gas through the apparatus such that at least of a portion of the particles in the gas stream are removed from the gas stream.

In one embodiment of the present invention, the particle removal means comprises means for diverting the flow of gas towards at least one wall of the apparatus adjacent the base of the apparatus. Preferably, gas diverted in this manner may then flow upwards in order to pass through the one or more outlets in the apparatus. The resulting change in velocity of the gas stream may result in at least a portion of the particles contained in the gas stream dropping out of the gas stream.

Preferably, the particle removal means is located in a lower portion of the apparatus. In some embodiments of the invention, the particle removal means is connected to the base of the apparatus and extends upwardly therefrom. In one embodiment of the present invention, the particle removal means is substantially pyramidal in shape, tapering as it extends upwardly into the apparatus. In this embodiment of the invention, the sides of the pyramid may be flat, concave, convex, or consist of two or more inclined surfaces. Each side of the pyramid may be the same or different to the other side of the pyramid. However, the skilled addressee will understand that the particle removal means may be of any suitable shape provided that it serves to divert the flow of gas through the apparatus towards the junction between the base of the apparatus and a side wall of the apparatus.

The particle removal means may be constructed from any suitable material, such as, but not limited to, metal, wood, plastic and the like.

The particles removed from the gas stream by the particle removal means are collected by the particle collection means. In one embodiment of the invention, the particle collection means comprises the point at which a side wall of the apparatus joins the base of the apparatus. However, in other embodiment of the invention, the particle collection means may comprise a pit, well, recess, trough or the like into which the collected particles may fall. The collected particles may be removed from the apparatus either manually (i.e. when the apparatus is stopped, such as in batch operation of the apparatus) or automatically, such as, but not limited to, removing the particles under gravity, by suction or by blowing the particles out of the apparatus. The collected particles may be removed directly to waste, may be recycled to the industrial process or may be sent for further processing (such as for separation of the different types or sizes of particles) or any combination thereof.

In another aspect, the present invention provides an apparatus for cleaning a gas stream, the apparatus comprising a housing having at least one inlet for supplying a gas stream, at least one outlet for removing a gas stream from the housing, flow diversion means for causing a gas stream flowing into the housing to change direction in the housing and cause particles or liquids entrained in the gas stream to be removed

from the gas stream prior to the gas stream leaving via the at least one outlet.

In one embodiment, the apparatus may further comprise one or more filters for removing a gaseous component or gaseous components from the gas stream, the one or more filters being located such that particles or liquids entrained in the gas stream supplied to the housing have been removed prior to the gas stream passing through the one or more outlets. The one or more filters may be located in the one or more outlets.

The skilled addressee will understand that while the present apparatus is described with particular reference to spray booths, it is equally applicable to a wide range of applications in which an exhaust gas must be cleaned prior to release to the atmosphere.

Brief Description of the Drawings. An embodiment of the invention will be described with reference to the following drawings in which: Figure 1 illustrates a cross-sectional side elevation of an apparatus according to an embodiment of the present invention;

Figure 2 illustrates a perspective view of the particle removal means of the invention according to one embodiment;

Figure 3 illustrates a perspective view of the apparatus according to an embodiment of the present invention; Figure 4 illustrates a cross-sectional side elevation of an apparatus according to an alternative embodiment of the present invention.

Detailed Description of the Drawings.

It will be appreciated that the drawings have been provided for the purposes of illustrating preferred embodiments of the present invention and that the invention should not be considered to be limited solely to the features as shown in the drawings.

In Figure 1 there is shown an apparatus for cleaning a gas stream according to an embodiment of the present invention. The apparatus comprises a housing 10 having an inlet 11 located in an upper surface 12 of the housing 10. Gas 14 entering the

housing 10 through the inlet 11 is channeled towards the particle removal means 15 by air diverters 16 in the form of a four-sided Venturi.

The air diverters 16 illustrated in Figure 1 are provided with a plurality of reed valves 24 on each side of the air diverters 16 at the lower edge of the air diverters 16. The reed valves 24 impart a "fluttering" effect to the gas stream 14, giving the gas stream 14 a more erratic path and directing the gas stream 14 onto the particle removal means 15.

The particle removal means 15 of the invention as illustrated in Figure 1 is in the form of a pyramid extending upwardly from the base 17 of the housing 10. The shape of the particle removal means 15 causes gas 18 flowing past the particle removal means 15 to be directed towards a junction between the base 17 of the housing 10 and a side wall 19 of the housing 10. As the gas 18 approaches the side wall 19 it is diverted upwards, thus changing direction and/or losing velocity. As a result of this change in direction and/or loss of velocity, solid particles 20 suspended in the gas 18 are dropped out of the gas 18 and are collected by the particle collection means, which, in the embodiment of the invention illustrated in Figure 1, comprise the junction between the base 17 and the side wall 19.

Once the particles 20 have been removed from the gas 18, the gas 18 then exits the housing 10 through a number of outlets 21. The outlets 21 are provided with filters 13 adapted to remove any remaining particles and/or undesirable gases from the gas stream 18.

In Figure 2 there is shown the particle removal means 15 according to an embodiment of the invention. The particle removal means 15 is in the form of a pyramid. Each side 22 of the particle removal means 15 comprises a pair of inclined surfaces 23 angled inwardly towards one another. The resulting shape of the sides 22 of the particle removal means 15 serves to channel the gas stream that passes over the particle removal means towards the junction between a side wall and the base of the housing (not shown), changing the directin of and/or reducing the velocity of the gas stream and dropping solid particles (not shown) out of the gas stream.

In Figure 3 there is illustrated a perspective view of the housing 10 according to an embodiment of the present invention. Exhaust gas 14 enters the housing 10 through an inlet 11 located in an upper surface 12 of the housing 10. The inlet 11 is provided with one or more air diverters (obscured) which increase the velocity of the exhaust gas stream 14, as well as directing the gas stream 14 into the particle removal means (obscured). Solid particles (not shown) are removed from the exhaust gas stream 14 by the particle removal means (obscured) located inside the housing 10.

Gas that has had at least some of the particles removed 18 exits the housing 10 through outlets 21 located on the side walls 19 of the housing 10. Each of the outlets 21 is provided with filter means 13 to remove any remaining particles and/or undesirable gases from the gas stream 18 exiting the housing 10.

In Figure 4, there is shown an apparatus for cleaning a gas stream according to an alternative embodiment of the present invention. The apparatus comprises a housing 10 having an inlet 11 located in an upper surface 12 of the housing 10. Gas 14 entering the housing 10 through the inlet 11 is channeled towards the particle removal means 15 by air diverters 16 in the form of a four-sided Venturi.

The air diverters 16 illustrated in Figure 1 are provided with a plurality of reed valves 24 on each side of the air diverters 16 at the lower edge of the air diverters 16. The reed valves 24 impart a "fluttering" effect to the gas stream 14, giving the gas stream 14 a more erratic path and directing the gas stream 14 onto the particle removal means 15. As can be seen in Figure 4, the reed valves 24 extend downwardly from the air diverters 16 such that a part of the particle removal means 15 is covered by the reed valves 24.

The particle removal means 15 of the invention as illustrated in Fig 4 is in the form of a pyramid extending upwardly from the base 17 of the housing 10. The shape of the particle removal means 15 causes gas 18 flowing past the particle removal means 15 to be directed towards a junction between the base 17 of the housing 10 and a side wall 19 of the housing 10. As the gas 18 approaches the side wall 19 it is diverted