REVERSE PULSE CLEANING ENHANCEMENT FOR CARTRIDGE FILTER AIR FILTRATION SYSTEM

Abstract: The present invention provides a filter apparatus for use in air pollution control which includes at least one hollow filter cartridge disposed within a housing cabinet. Contaminated air is introduced into the housing cabinet through an inlet and is caused to flow into an exhaust chamber adjacent the housing cabinet after passing through the filter cartridges in the housing cabinet to remove airborne particulates. Compressed air injectors are also provided for selectively directing a reverse pulse of air into the openings of the filter cartridges from the exhaust chamber side thereof so that the reverse air pulse enters the filter cartridges and flows through the filter medium in the reverse direction of that of the contamined air flow to thereby remove accumulated contaminates from the filter medium. In order to improve periodic cleaning of the filters, elongated deflecting inserts are disposed within the filter cartridges to reduce the internal volume of the filter cartridges. The compressed air injectors include preferably tapered nozzles positioned and aligned with a corresponding opening such that the reverse air pulses can deflect off of the inserts disposed within the walls of the filter cartridges and, as a result, against substantially the entire interior surface of the filter medium so as to effect even cleaning of substantially the entire length of the filter assembly.

Description: REVERSE PULSE CLEANING ENHANCEMENT FOR CARTRIDGE FILTER AIR FILTRATION SYSTEM TECHNICAL FIELD The present invention relates generally to air pollution control equipment such as fabric filter dust collectors and is particularly directed to such apparatus that utilize a reverse stream of compressed air to periodically clean the filter medium in dust collector systems. BACKGROUND OF THE INVENTION In many industrial operations, air or other gases produced from various processes frequently contain entrained particulate matter therein generated as a byproduct or waste material from the particular process. In many instances, it is desirable to remove some or all of the particulate material from the gas flow stream. Obviously, before such gases can be, or should be, discharged through various downstream equipment into the atmosphere, it is frequently desirable to filter the contaminated gas streams and to obtain substantial removal of the particulate material from those streams. Accordingly, a variety of air filtration systems have been developed to effect particulate removal from various industrial processes. For example, in a particular class of air filter systems commonly referred to as dust collectors, a series of filter cartridges containing filter media are provided that operate with high efficiency and that are effective in filtering a broad range of variably sized particles. Typical dust collector systems of this type are manufactured by United Air Specialists, Inc. of Cincinnati, Ohio under the trademark DUST-HOG®. A dust collector of this type generally contains at least one such filter cartridge, although many more cartridges may be employed depending on the size of the collector and the needs of the particular application. Each filter cartridge generally includes filter media made of conventional fabric, paper or other material which is pervious to the air but not to airborne contaminates. The filter cartridges are generally substantially cylindrical and include an interior volume. The filter media is often mechanically supported by a substantially cylindrical metal screen or mesh which serves to provide mechanical support for the media but that has a generally open construction so as not to interfere with airflow therethrough. Filter cartridges are preferably supported within a housing cabinet by means of removable flow blocking end caps which further may serve as doors for removing or providing maintenance access for the filter cartridges. As particulate laden gases pass through a filter cartridge in a dust collector, the filter media retains the particulate matter on its exterior surface and does not allow most or all of the particulate matter to pass therethrough. As this process continues, upon repeated operation of the dust collector, a layer of dust builds on the surfaces of the various filter media. As a result, increased amounts of energy are required to force the air or gases through the filter media. Accordingly, it is desirable to periodically remove the buildup of the dust layers that collect on the surfaces of the dust collector filters. To clean the filter cartridges of a standard dust collector system, it is well known to use a reverse pulse of compressed air to remove particulates and contaminants which have accumulated on the surfaces of the filter cartridges. In such a dust collector system, during a cleaning cycle, a reverse air pulse jet cleaning system periodically injects compressed air into the interior volumes of the filter cartridges in a direction generally opposite that of the direction of the clean air exiting the cartridges during normal operation, thus, during such a cleaning pulse, temporarily reversing air flow direction. This reverse pulse cleaning may take place either during normal filtering operations or during downtime periods when the dust collector is not in normal operation or is turned off. Specifically, during the cleaning cycle, the pulses of air inside the various filter cartridges provide a reverse air flow effect essentially radially outward from the interior of the cartridges and through the filter media in a direction opposite that of the direction of airflow during normal filtering operation. This reverse airflow during the cleaning cycle allows for the dust buildup on the filters to be released so that it can be collected in an underlying housing cabinet, or other such receptacle as is known in the art, and subsequently properly disposed of. Although the efficiency of the prior art dust collector systems has been improved through the use of reverse pulse cleaning systems to remove contaminants which have accumulated on the filter media, there remains a need to improve the efficiency of the reverse pulse cleaning systems in order to improve the effectiveness of the overall filter cleaning process. For example, reverse air pulse jet systems of the type described above may be less effective when used with filter cartridges having relatively large internal diameters and, as a result, larger internal volumes. Because of the relatively large internal volumes in such filter cartridges, conventional reverse pulse jet systems may be less effective in reversing the airflow in the filter cartridges during the cleaning pulses. Accordingly, when used with such large diameter filter cartridges, conventional reverse pulse jet systems generally may not create the necessary reverse air flow within the filter cartridge to achieve the desired cleaning effect. An additional problem associated with prior art reverse pulse cleaning systems is that such systems may fail to provide uniform cleaning along the entire length of the filter cartridge. Specifically, while such systems generally provide effective cleaning of those portions of the filter medium most distant from the compressed air nozzle, they may not provide acceptable levels of cleaning in those areas of the filter media closest to the source of the compressed air blast. SUMMARY OF THE INVENTION Accordingly, it is a primary object of the present invention to overcome the above-described limitations and disadvantages in the air pollution control equipment and dust collector prior art. An additional object of the present invention is to provide an improved dust collector system that is capable of the periodic discharge of accumulated particulates from the various filter media of the dust collector with increased economic and operational efficiency. Yet another object of the present invention is to provide an improved dust collector system that is capable of effectively and more evenly cleaning the entire length of the various filter media of the dust collector. Still another object of the present invention is to provide an improved dust collector system that is capable of effectively cleaning filter cartridges of relatively large internal diameter. Yet another object of the present invention is to provide an improved dust collector system that incorporates inserts within the internal volumes of the various filter cartridges to increase the efficiency of the periodic filter cleaning process. Additional objects, advantages and other novel features of the invention will be set forth in part in the description that follows and in part will become apparent to those skilled in the art upon examination of the following or may be learned with the practice of the invention as described and claimed herein. To achieve the foregoing and other objects, and in accordance with one aspect of the present invention, an improved air filtration system is provided including a housing cabinet, an exhaust chamber, and at least one filter assembly disposed in a housing cabinet and open to the exhaust chamber. The housing cabinet is generally sealed from the exhaust chamber except where the exhaust chamber is in communication with the filter media of the filter cartridges. The filter assemblies communicate with the exhaust chamber through corresponding openings therein. Each filter assembly, which may be a cylindrical hollow filter cartridge, further includes inner walls. An elongated insert is disposed within the interior volume of each filter cartridge. The housing cabinet further includes at least one inlet for introducing contaminate laden gaseous fluid into the housing cabinet. A conventional fan is connected to the exhaust chamber by ducting, or by direct contact with the exhaust chamber, thus drawing the contaminated air into the exhaust chamber after passing through the filter media. As a result, airborne contaminates are accumulated on the exterior surfaces of the filter media. Compressed air injectors are also provided for selectively directing a reverse pulse of air into the openings of the filter cartridges from the exhaust chamber side thereof so that the reverse air pulse enters the filter cartridges and flows through the filter media in the reverse direction to that of the contaminated air flow to thereby periodically remove accumulated contaminates from the filter media. The filter assembly is also provided with elongated inserts which occupy portions of the interior volumes of the filter cartridges thus effectively reducing the internal volumes of the cartridges. The compressed air injectors include nozzles positioned and aligned with a corresponding filter cartridge aperture such that the reverse air pulses can deflect off of the inserts disposed within the filter cartridges. Although it is preferable to use tapered nozzles to direct the reverse air pulses, it will be understood that the nozzles may be of uniform or diverging cross-sectional area as well. The reverse air pulses, after deflecting off of the inserts, impact against substantially the entire interior surface of the filter media, including the portion of the interior surface of the filter media most closely disposed to the source of the compressed air blast, so as to effect even cleaning of substantially the entire length of the filter cartridge. Accordingly, and as is especially advantageous in filter cartridges with large internal diameters, a blast of compressed air impacts the interior walls of the filter cartridge with increased pressure as compared with a similar blast in a filter cartridge lacking the insert, thus enabling filter cartridges with large internal volumes to be more effectively cleaned. Still other objects of the present invention will become apparent to those skilled in this art from the following description and drawing wherein there is described and shown a preferred embodiment of the invention. As will be realized, the invention is capable of other different embodiments, and its several details are capable of modification in various, obvious aspects all without departing from the invention. Accordingly, the drawings and descriptions will be regarded as illustrative in nature and not as restrictive. BRIEF DESCRIPTION OF THE DRAWING The accompanying drawing incorporated in and forming a part of the specification illustrates several aspects of the present invention, and together with the description and claims serves to explain the principles of the invention. In the accompanying drawing: Figure 1 is a cross-sectional partially diagrammatic side view of the air filtration system of the present invention showing the direction of contaminated air flow through the filter cartridges and exhaust chamber; Figure 2 is a front cross-sectional partially diagrammatic view of the air filtration system of the present invention showing the flow direction of contaminated air through the various filter cartridges; Figure 3 is a side cross-sectional partially diagrammatic view showing the air filtration system of the present invention in cleaning mode with the inserts of the filter cartridges in place; Figure 4 is a cross-sectional partially diagrammatic view of a prior art air filtration system in cleaning mode; Figure 5 is an enlarged cross-sectional partially diagrammatic side view of an alternate embodiment of a portion of a filter cartridge of the air filtration system of the present invention; Figure 6 is an enlarged cross-sectional partially diagrammatic side view of another alternate embodiment of a portion of a filter cartridge of the air filtration system of the present invention; Figure 7 is an enlarged cross-sectional partially diagrammatic side view of another alternate embodiment of a portion of a filter cartridge of the air filtration system of the present invention; Figure 8 is an enlarged cross-sectional partially diagrammatic side view of another alternate embodiment of a portion of a filter cartridge of the air filtration system of the present invention; Fig. 9 is a side cross sectional partially diagrammatic view of an alternate embodiment of the air filtration system of the present invention showing the flow direction of contaminated air through a vertically disposed filter cartridge; and Fig. 10 is a cross sectional partially diagrammatic side view of an alternate embodiment of a filter cartridge insert of the air filtration system of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A common type of filter apparatus to which this air filtration system is particularly well suited is referred to as a cartridge dust collector or cartridge dust collector system. The invention will be discussed as embodied in such a system but it will be appreciated that the invention has wider application.. Reference will now be made in detail to the present preferred embodiment of the invention, an example of which is illustrated in the accompanying drawing, wherein like numerals indicate corresponding elements throughout the figures of the drawing. Figure 1 illustrates generally at 10 the air filtration system incorporating the improvement of the present invention as described hereinafter. As it will be understood, the improvement of the present invention may be used in conjunction with cartridge type dust collector systems such as those manufactured by United Air Specialists, Inc. of Cincinnati, Ohio under the registered trademark DUST-HOG*. For illustrative purposes, the dust collector system described herein, exclusive of the improvement of the present invention, is a typical four cartridge horizontal Dust-Hog* dust collector system. As shown in Figures 1 and 2, the air filtration system 10 includes a housing cabinet 12 in which a series of elongated generally cylindrical filter cartridges 16 are disposed generally horizontally in a manner to be described hereinafter. The air filtration system 10 also includes an exhaust or clean air chamber 14 disposed substantially adjacent with the housing cabinet 12. The filter cartridges 16 each include a gas flow aperture 30 in communication with the exhaust chamber 14. Each filter cartridge 16 further includes a filter medium 17 having inner walls 18. The housing cabinet 12 is substantially sealed from the exhaust chamber 14 except through the gaseous medium flow apertures 30 of the filter cartridges 16. According to one important aspect of the present invention, and as will be described in detail hereinafter, each filter cartridge 16 of the air filtration system 10 further includes an elongated insert 20 disposed, in the preferred embodiment, within the inner walls 18 of the filter medium 17 and substantially coaxially with the filter cartridge 16 in which the insert is disposed. The housing cabinet 12 further includes at least one inlet 34 for introducing contaminated or particulate laden gases into the housing cabinet. The contaminated air can come from any source, for example from fume collector hoods at welding stations for collecting welding smoke or at grinding stations for collecting grinding dust. A conventional fan (not shown) is generally connected by ducting in any manner as is known in the art to an outlet opening in the exhaust chamber 14. The fan draws air from the exhaust chamber 14, thereby creating a pressure drop between exhaust chamber 14 and the housing cabinet 12, thus causing a flow of contaminated and particulate laden air into the housing cabinet 12 through the inlet 34 (see direction arrows A,), through the filter cartridges 20 (see direction arrows A 2 ), through the apertures 30 and into the exhaust chamber 14 (see direction arrows A 3 ). Each filter cartridge 16 includes filter medium 17 made of conventional material which is pervious to the air but not to airborne contaminates such as paper, synthetic cloth, natural fabric or any combination of these or any other suitable air pervious materials as are known in the art. The medium 17 and filter cartridge 16 are preferably substantially cylindrical with a circular cross-section of constant diameter, though each cartridge might be tapered depending on the needs of the particular dust collecting application. Although cartridges of circular cross-section are preferred, the medium 17 and cartridges 16 may be of square, triangular, oval, elliptical, or essentially any other suitably shaped cross-section. The filter medium 17 generally comprises a fabric or other pervious material supported by a substantially cylindrical screen or mesh (not shown) of metal or other material as is well known in the art which serves to provide mechanical support for the medium but that has a generally open construction so as not to interfere with airflow therethrough. Filter cartridges 16 are supported within housing cabinet 12 by means of removable end plates 19 which further serve as doors for removing or providing maintenance access for filter cartridges 16. Preferably filter cartridges 16 are substantially horizontally disposed within the housing cabinet 12. This arrangement minimizes the amount of particulate spillage when filter cartridges are removed or replaced as compared with vertically disposed filter cartridges. Although it is preferred that the filter cartridges be substantially horizontally disposed, the improvement of the present invention is capable of use in cartridge filter systems using inclined, declined, or substantially vertically disposed filter cartridges as well. As stated above, filter medium 17 is impervious to airborne contaminates 36 which, when their flow is interrupted by the filter medium, either adhere to the outer surface of the filter medium or fall directly into a hopper 32 underlying the housing cabinet, as shown in Figures 2 and 3, and subsequently into storage drum 38. As shown in Fig. 1 , filtered air is then drawn into exhaust chamber 14. Upon repeated operation of the dust collector, layers of dust and particulates build on the outer surfaces of filter media. As a result, increased amounts of energy are required to draw the contaminated air through the filters. Specifically, excessive particulate buildup substantially increases the pressure drop across the filter medium 17, thereby increasing the energy requirements for operation of the dust collector and thus adversely impacting the operating efficiency of the dust collector. Accordingly, it will be understood that it is desirable that excessive buildup of contaminates on the filter cartridges should be avoided. Without adequate cleaning, buildup of excessive particulate material on the filter media can accumulate to such a degree where airflow through the filter cartridges 16 is essentially blocked off. Accordingly, periodic cleaning of the filter cartridge 16 to remove a portion of the accumulated particulate matter has long been recognized as desirable and various arrangements and methods have been proposed to achieve that cleaning. As best shown in Figure 3, and according to an important aspect of the present invention, the air filtering system 10 includes an improved arrangement for periodically cleaning the accumulated particulate material from the filter cartridges 16. Specifically, the cleaning arrangement includes one or more compressed air injectors 28. The compressed air injectors further include at least one nozzle unit 26. Preferably the nozzles 26 are tapered in order to produce a better air pulse characteristic during the cleaning cycles. More preferably the nozzles have an internal diverging taper of about 4 to 6 degrees. The nozzle units 26 are preferably positioned so that an opening of each nozzle unit is positioned in close proximity to and substantially aligned with one of the gaseous flow apertures 30. During the cleaning cycles, the compressed air injectors 28 selectively direct a reverse stream of compressed air into the nozzle units 26 so that reverse streams of compressed air enter a corresponding filter cartridge 16 through a flow aperture 30 in a direction opposite of that of the flow direction, during normal filtering mode, of the contaminate laden gaseous fluid. The air pulses are "reverse" in the sense that they are in the direction opposite to the normal flow of air through the apparatus during a regular filtering cycle. The pulses are of a short duration and they interrupt the filtering operation of the filter cartridges 16 for only a relatively short period of time. The reverse pulses of air advantageously impact the interior walls of the cartridge and, as a result, dislodge the accumulated particulate material from the surfaces of the filter media 17 of the filter cartridges 16 so that it falls into the hopper 32 underlying the housing cabinet 12 and into drum 36 where it can be safely removed and discarded. Additionally, the pulses of air during the cleaning cycles may be of such a force so as to temporarily flex the filter media upon impact so as to further facilitate the dislodging of accumulated particulates. As shown in Figure 4 and as it is known in the art, reverse pulse air jet cleaning systems of this type impart a generally cone shaped blast of air, (see arrows C), into apertures 30 of filter cartridges 16. As described previously, as the injectors 28 propel compressed air into the interior volume of the filter cartridges, the air within the filter cartridges will attempt to expand thus providing a reverse air effect across the filter media, thereby allowing the dust buildup on the filter cartridges to be released due to the diverging geometry of the air blast. However, as shown in Figure 4, due to the diverging shape of the air blast, the stream of compressed air may fail to expand to the filter walls in order to provide adequate contact with and resulting cleaning of that portion of the filter cartridges closest to the apertures 30. Accordingly, although prior art systems have generally proved effective for cleaning portions of the filter cartridges farthest from the point of introduction of reverse pulse compressed air, they have proven to be inadequate for providing even cleaning along the length of the filter cartridges and thus have not been capable of providing an efficient means of cleaning along the entire length of the filter cartridges. As shown in Figures 1-3 and according to an important aspect of the present invention, the filter cartridges 16 each include an elongated insert 20 preferably disposed generally coaxially within the interior volume of the filter cartridges. The inserts 20 may be metallic, of plastic composition, or may be comprised of any other suitable rigid, semi-rigid or flexible material. Further, inserts 20 may be either solid or hollow. Additionally, the insert may be one continuous length of material or may be discontinuous comprising several substantially disjointed segments along the length of the cartridge. Preferably the insert is molded from an engineering thermoplastic. The cartridge can be molded by any method known in the art, including injection molding, compression molding, transfer molding or thermoforming. Suitable thermoplastics include, but are not limited to, polyesters, styrenes, polycarbonates, polypropylenes, polyethylenes, acrylonitrile butadiene styrene and modified polyphenylene oxides and blends thereof. The thermoplastics may be filled or unfilled. Suitable fillers can include, but are not limited to minerals, glass or graphite. In the preferred but non-limiting embodiment illustrated, each of the elongated inserts 20 further includes a deflecting cone portion 22 that is disposed on the end of a corresponding insert that is most closely disposed to the aperture 30 in communication with the exhaust chamber 14. Preferably, the deflecting cone 22 comprises sloped sides of an angle in a range of between about 20° to about 60° with the longitudinal axis of the insert. In addition, the deflecting cone portions 22 preferably include a vertex 24 that is substantially disposed near the center of the corresponding aperture 30 and that is further substantially aligned with a corresponding nozzle 26 in such a manner so that the vertex 24 is generally impacted by the stream of air from the compressed air injectors 28 during the reverse pulse cleaning cycle. Although it is preferred that inserts 20 include a cone shaped deflecting portion 22, the deflecting portion of the inserts 20 may be pyramidal, partially spheroidal, or any other substantially convex or concave configuration suitable to deflect a portion of the compressed air blast in a direction toward the interior walls of cartridges 16. The introduction of inserts 20 allows for more even cleaning along the entire length of the filter cartridges, and as a result, facilitates a more efficient cleaning process. Specifically, during the reverse pulse cleaning cycle and as shown in Figure 3, a jet of compressed air B is released from nozzle 26 where it engages and subsequently deflects off of the sloped sides of cone 22. As also shown in Figure 3, this deflection allows for some portions of the streams of compressed air to be directed toward the surfaces of the filter cartridges 16 closest to the air pulse sources and, as a result, provide cleaning for those areas of the filter cartridges most closely disposed to the nozzles 26 in a much more efficient manner than in the prior art systems. In addition, during the reverse pulse cleaning cycle, a portion of the compressed air stream impacts and cleans portions of the filter farther from the compressed air source similar to the compressed air cleaning systems of the prior art. Further, inserts 20 are disposed and are configured such that they do not adversely impact the filtering process during the regular filtering mode. It will be understood that the distance between the vertex 24 and the corresponding aperture 30 in communication with the exhaust chamber 14 may be varied according to the needs of the particular process to maximize the efficiency of the cleaning process. Preferably, the distance between the vertex 24 and a corresponding aperture is in a range of between about -.5 inches to about 15 inches. In addition to facilitating more uniform cleaning over the lengths of filter cartridges 16, inserts 20 are dimensioned volumetrically to advantageously decrease the volumetric area inside the filter cartridges 16. As a result, the same amount of compressed air emitted by nozzles 26 can provide a larger resultant pressure against the interior walls of the filter cartridges 16 incorporating the inserts 20 of the present invention, as compared with prior art dust collectors having cartridges lacking the inserts of the present invention, thus allowing for better cleaning and increased filter dust release as compared with prior art reverse pulse systems. Notably, by decreasing the effective volume inside the filter cartridges 16 through the addition of inserts 20, the same amount of effective filter cleaning may be accomplished using a reduced amount of compressed air, thus resulting in a more efficient process. Further, the use of inserts 20 allow reverse air pulse cleaning systems to effectively and efficiently clean filters having relatively large cross-sectional diameters and relatively large interior volumes. By adding inserts 20 within such large diameter filters, the reverse pulses of air impact the interior walls of the filter cartridges with increased pressure as compared with similar reverse cleaning air pulses used in connection with cartridges lacking the inserts, thus enabling cartridges with large internal volumes to be more effectively cleaned. Preferably, in order to achieve improved cleaning of large diameter filter cartridges, elongated inserts 20 occupy a minimum of one tenth of the overall internal volume of the cartridge 16. Although the present invention has been described hereinabove, for illustrative purposes, for use in conjunction with a horizontal cartridge dust collector system, it should be appreciated that the improvement of the present invention may be used in conjunction with essentially any dust collector system regardless of the orientation of the filter cartridges. For example, and as shown in Fig. 9, the improvement of the present invention may be employed in a dust collector 50 having a vertically disposed filter cartridge 52 with an elongated insert 54. Similar to the horizontally configured cartridge dust collector, a fan (now shown) draws air from exhaust chamber 56, thereby creating a pressure drop between exhaust chamber 56 and cartridge housing cabinet 58. This causes a flow of contaminated and particulate laden air into cabinet 58 through the inlets 60 (see direction arrows X,), through the filter cartridge 52, and through outlets 62 in exhaust chamber 56 (see direction arrows X 2 ). Similar to the horizontally configured dust collector, the dust collector system 50 includes one or more compressed air injectors 64 to selectively inject a reverse stream of compressed air, during a reverse pulse cleaning cycle, against elongated insert 54 and towards the surfaces of the filter cartridge 52 to effect a more efficient cleaning process as described hereinabove. The filter contaminates may be collected in dust collecting drawer 66. It should be appreciated that the improvement of the present invention is capable of being retrofitted into and used with existing cartridge type dust collector systems. For example, as shown in Figure 2, inserts 20 may include a plurality of radially disposed spokes 25, or some other similar securing mechanisms, that are capable of holding an insert in place substantially coaxially, or off center, within the interior volume of an existing filter cartridge to realize the benefits derived from using the present invention. Further, it should be appreciated that the foregoing description of a preferred embodiment of the cartridge filter insert has been presented for the purposes of illustration and description. Obvious modifications or variations are possible in light of the above teachings. For example, and as shown in Figure 10, cartridge insert 70 may comprise an oblong unit mounted within cartridge 74, by means of support brackets 72, in alignment with compressed air injector 60 in order to achieve the above-described cartridge cleaning enhancements. As best shown in Figures 5-8, the exact configurations of the filter cartridges 16 and the inserts 20 may be varied according to the needs of the particular process to maximize the efficiency of the cleaning process. For example, as shown in Figure 5, the filter cartridge 16 may be of substantially uniform cross-section having an insert 20 with a cross-section that diminishes along the length of the insert in a direction toward the nozzle 26. Further, in this embodiment, deflecting cone portion 22 is disposed substantially adjacent nozzle 26. The location of cone portion 22 and the configuration of insert 20 enable a stream of compressed reverse air pulses imparted during the cleaning cycle to provide effective cleaning along the length of the cartridge. Specifically, because cone portion 22 is in close proximity to the nozzle 26, the cone 22 immediately deflects a portion of the cleaning air stream toward the portion of the internal walls of the cartridge 16 closest to the nozzle 26. As shown in Figure 6, and in another alternate embodiment of the improvement of the present invention, the filter cartridge 16 may have a cross- sectional diameter that diminishes along the length of the cartridge in a direction away from the nozzle 26 and an insert 20 of relatively large, but essentially uniform, cross-sectional diameter. Additionally, in this embodiment, the deflecting cone portion 22 has a relatively wide base, due to the large internal diameter of the tapered cartridge near the nozzle. Accordingly, the cone portion 22 advantageously deflects a portion of the compressed air blast at relatively sharp angles towards the portion of the internal walls of the cartridge closest to the nozzle. The insert of Figure 6 is especially adapted for use in cartridges of relatively large internal volumes and cross- sectional diameters. As shown in Figure 7, and in another alternate embodiment of the improvement of the present invention, the filter cartridge 16 and insert 20 may both be of relatively uniform cross-sectional diameter. In this embodiment, cone portion 22 is not disposed adjacent nozzle 26 but rather extends only minimally beyond the walls of cartridge 16. Cone portion 22 has relatively steeply pitched sides so as to deflect a portion of the reverse air cleaning pulse to the portion of the internal walls of the cartridge 16 closest to nozzle 26. As shown in Figure 8, and in another alternate embodiment of the improvement of the present invention, the filter cartridge 16 may have a cross- sectional diameter that diminishes along the length of the cartridge in a direction away from the nozzle 26 and an insert 20 of relatively large, but essentially uniform, cross- sectional diameter. Further, in this embodiment, deflecting cone portion 22 is disposed substantially adjacent nozzle 26. The location of cone portion 22 and the configuration of insert 20 enable a reverse pulse of cleaning air imparted during the cleaning cycle to provide effective cleaning along the length of the cartridge. Specifically, because cone portion 22 is in close proximity to the nozzle 26, cone portion 22 immediately deflects a portion of the reverse air pulse toward the portion of the internal walls of the cartridge 16 closest to nozzle 26. As mentioned previously, the exact configurations of the filter cartridges 16 and the inserts 20 may be varied according to the needs of the particular process to maximize the efficiency of the cleaning process. Preferably, when it is desirable to use a filter cartridge of substantially uniform cross-sectional area, such as shown in Figures 5 and 7, the inner and outer diameters of the filter cartridges are in a range of between about 6 inches to about 24 inches. Further, when it is desirable to use a filter cartridge 16 that has a cross-sectional diameter that diminishes along the length of the cartridge in a direction away from the nozzle 26, such as shown in Figures 6 and 8, it is preferable to use a cartridge that tapers from an end of relatively wide cross sectional area, preferably having inner and outer diameters in a range of about 6 inches to about 24 inches, to an end of relatively narrow cross-sectional area, preferably having inner and outer diameters in a range of about 6 inches to about 18 inches. Additionally, when it is desirable to use an insert 20 of substantially uniform cross-sectional area, such as shown in Figures 7 and 8, the outer diameters of the inserts are preferably in a range of between about 1 inch to about 16 inches. Further, when it is desirable to use an insert 20 that has a cross-sectional diameter that increases along the length of the insert in a direction away from the nozzle 26, such as shown in Figures 5 and 6, it is preferable to use an insert that widens from an end of relatively narrow cross sectional area, preferably having an outer diameter in a range of between about 1 inch to about 14 inches, to an end of relatively wide cross- sectional area, preferably having an outer diameter in a range of between about 6 inches to about 18 inches. It will be understood that the cross-sectional shape of the inserts 20 described herein may be circular, square, triangular or any other suitable configuration. The foregoing description of a preferred embodiment of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiment was chosen and described in order to best illustrate the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended thereto.

Claims: CLAIMS What is claimed is: 1. A filter apparatus comprising: a housing cabinet including an exhaust chamber, at least one filter cartridge including a filter media for collecting particulate material on the interior surface thereof disposed within said housing cabinet, said cartridge having a gaseous medium flow aperture communicating with said exhaust chamber, an elongated insert disposed within said cartridge, at least one nozzle unit having an opening positioned in close proximity to and being aligned with a corresponding gaseous flow aperture and a corresponding insert of said filter cartridge; and at least one compressed air injector selectively directing a reverse stream of compressed air into said nozzle units so that said reverse streams of compressed air enter a corresponding filter cartridge through a corresponding flow aperture in a direction opposite that of the direction of the flow of the said contaminate laden gaseous fluid to remove a substantial portion of said collected particulate from the exterior surface of said filter cartridges. 2. The filter apparatus of claim 1 wherein said at least one nozzle is tapered. 3. The filter apparatus of claim 2 wherein said at least one nozzle has an internal taper of between 4 and 6 degrees. 4. The filter apparatus of claim 1 wherein each of said elongated inserts further includes a deflecting cone, said deflecting cones being disposed on an end of a corresponding insert, said deflecting cones further including a vertex substantially aligned with one of said nozzles. 5. The filter apparatus of claim 4 wherein said filter cartridges further have a substantially uniform cross sectional area. 6. The filter apparatus of claim 5 wherein said filter cartridges are substantially cylindrical. 7. The filter apparatus of claim 6 wherein said inserts are substantially tapered. 8. The filter apparatus of claim 6 wherein said inserts further have a substantially uniform cross sectional area. 9. The filter apparatus of claim 8 wherein said inserts are substantially cylindrical. 10. The filter apparatus of claim 4 wherein said filter cartridges are substantially tapered. 11. The filter apparatus of claim 10 wherein said inserts are substantially tapered. 12. The filter apparatus of claim 10 wherein said inserts further have a substantially uniform cross sectional area. 13. The filter apparatus of claim 12 wherein said inserts are substantially cylindrical. 14. The filter apparatus of claim 4 wherein said inserts are of a length of between about 10 inches and about 60 inches. 15. The filter apparatus of claim 14 wherein said inserts further have outer diameters in a range of between about 1 inch and about 18 inches. 16. The filter apparatus of claim 15 wherein said deflecting cones further comprise sloped sides that form an angle with the longitudinal axis of said insert in a range of between about 20" to about 60°. 17. The filter apparatus of claim 16 wherein the distance between said vertex and said nozzle is in a range of between about -.5 inches and about 15 inches. 18. The filter apparatus of claim 15 wherein said inserts comprise a first end having an outer diameter in a range of between about 1 inches and about 14 inches to a second end having an outer diameter in a range of between about 6 inches and about 18 inches. 19. The filter apparatus of claim 17 wherein said inserts are molded from an engineering thermoplastic. 20. The filter apparatus of claim 15 wherein said cartridges comprise inner and outer diameters in a range of between about 6 inches and about 24 inches.

Inventors: LEFLER KEVIN D, LUNDBERG MARK R, LEFLER, KEVIN, D., LUNDBERG, MARK, R.
Applicants: UNITED AIR SPECIALISTS
Application year: 1998
Main classification: B01D46
IPC codes: B01D46