Apparatus and method for removing particulates from a fluid stream

An assembly for cleaning particulates from fluid streams has a primary and secondary centrifuge collectors and may employ negative pressure to produce the fluid stream. The primary centrifuge collector forms an outer vortex to remove larger particles, then an inner vortex to produce higher centrifugal forces upon and to remove a portion of the particulates. In the secondary centrifuge collector, a plurality of secondary centrifuge collector units are present. The partially cleaned fluid stream enters one of the secondary centrifuge collector units, where swirl vanes form an outer vortex. The fluid flow travels along the secondary vortex to the bottom of the secondary centrifuge collector unit, where the direction of the fluid flow is reversed and the fluid flow is subjected to a higher energy inner vortex. The centrifugal forces exerted by these vortices convey the particulates to the walls of the secondary centrifuge units, where the particulates are evacuated initially by gravity for disposal. The cleaned fluid flow may then be released into the environment.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to fluid cleaning devices and, in particular, this invention relates to devices for cleaning fluid streams without the use of filters.

Particulate-laden fluid streams from industrial processes must often be cleaned before being released into the environment. For example, hot asphalt mix plants with direct-fired rotary drum dryers generated untreated exhaust gas streams that will not pass current or future codes until the particulates are removed therefrom. Presently, the best available method of doing so is the filter bag house, which is inefficient and expensive to operate. These filter bag houses use filters which become progressively more plugged by oil and particulates. Consequently, these filter bag houses become progressively more inefficient as the filters become progressively more plugged with materials being cleaned from the air stream. Additionally, replacing or cleaning the bag filters is time consuming and costly and often requires that the plants discontinue operation during maintenance activities of this nature. Therefore, there is needed a device and method which efficiently eliminates particulates and other pollutants from industrial air streams without using filters to do so.

SUMMARY OF THE INVENTION

This invention substantially meets the aforementioned needs of the industry by providing an assembly, which does not employ filters or bags when cleaning particulates or other pollutants from fluid streams, such as gas-borne dusts; hence does not become progressively more plugged with removed particulates during use. Such fluid streams with gas-borne particulates arise from such industrial applications as hot mix asphalt plants, cement plants, coal fired boilers, foundries, ethanol plants, and the like. In the instant invention, there is no fabric or other filter material. Thus, there is no filter to be plugged by oil or particulate accumulation or to be cleaned (shaken out) or replaced periodically. Moreover, the cleaning assembly of this invention has the capability of running continuously and is immune to high temperatures, as well as fires which often occur in the filter bag houses of the prior art. The present invention is at least as efficient, usually more efficient, as the bag houses of the prior art, because the present invention exerts, in its spin cycle, a force on the particulates, which may be 9000 times the force of gravity. It is believed that this invention will involve considerably lower costs, both to build and to operate, than the foregoing cleaning facilities of the prior art. Moreover, construction of the unit of this invention involves components and parts easily obtainable by those of ordinary skill in the art. Thus, there are no particular or special needs for fabrication of especially built parts.

In this invention, particulate-containing air may be first passed through a high performance hydroclone-design primary centrifuge dust collector, such as a vertical or horizontal primary centrifuge (or cyclone) to reduce particulate load on a follow-up high efficiency secondary centrifuge collector. This two-stage combination results in a final, efficiently cleaned, air stream equal to, or exceeding, the performance of bag houses. The secondary centrifuge has an axial vane design, which passes air from the primary centrifuge through a ring of swirl vanes, which are mounted horizontally between an inlet cylinder and an outlet cylinder to produce a uniform non-turbulent spin or vortex. The dust-containing air spends downwardly and is drawn radially inwardly to exit through the central, tapered outlet, thereby producing a vortex of extremely high spin velocity. This high tangential velocity at a very small radius creates a centrifugal force on the particulates often more than 9000 times the force of gravity, thereby separating the particulates from the air flow. A circular plate may be centrally mounted just above the air exit opening to provide a vortex cut-off to thereby prevent re-entrainment of collected dust (separated particulates). This feature in the primary centrifuge is provided by the body vertical and plate. Dust is centrifuged to the outer wall in the secondary centrifuge, where it slides downwardly to the collector outlet. When in the collector outlet, disposal may be provided by screw conveyor, collector belt, or the like, then followed by a gravity-operated air valve or rotary air-lock.

It is therefore an object of this invention, to provide an assembly for separating particulates from a fluid stream, the assembly comprising a primary centrifuge collector and a secondary centrifuge collector. The primary centrifuge collector may receive the fluid stream with particulates and may comprise an outer housing and an egress conveying the fluid stream away from the primary centrifuge collector. The secondary centrifuge collector may comprise a plurality of secondary centrifuge collector units positioned within a secondary centrifuge collector housing. Each secondary collector unit may receive a portion of the fluid stream from the primary centrifuge collector and may remove more of the particulates from the fluid stream. Each secondary centrifuge collector unit may comprise an outer cylinder and a vaned outlet element, which may comprise a concentric insert disposed with respect to the outer cylinder.

A further object of the invention is to provide a secondary centrifuge, which may include a housing and a plurality of secondary centrifuge units disposed within the housing. Each of the secondary centrifuge units may include an outer cylinder and a vaned outlet element, which may be generally concentric to the outer cylinder and which may receive a vortexed air stream induced by the vanes. The vortexed air stream may centrifugally separate the particulates.

Yet another object is to provide a method of cleaning particulates from an air stream by centrifugal force by means of the foregoing assembly for separating particulates and/or secondary centrifuge.

It is a feature of this invention that centrifugal force, rather than filters, is used to separate particulates from a fluid stream. It is an advantage of the foregoing feature that cleaning fluid streams by the assembly of this invention may be affected without changing or cleaning air filters. It is another advantage of the foregoing feature that the progressively less efficient fluid-cleaning devices of the prior art are replaced by the instant assembly, in which there are no filters to be progressively plugged by particulates.

It is another feature of this invention that a plurality of secondary centrifuge collector units are housed within a singular centrifuge collector housing. It is an advantage of the foregoing feature that particulates separated from fluid streams by the secondary collector units may be evacuated by a single disposal assembly in one embodiment of this invention.

It is yet another feature of this invention to provide secondary centrifuge collectors having swirl vanes arranged horizontally. It is an advantage of the foregoing feature that the swirl vanes impart a non-turbulent spin to form a vortex for removing particulates.

It is still another feature of this invention to provide secondary centrifuge collectors having internal substantially coned shapes at central outlets. It is an advantage of the foregoing feature that the internal substantially coned shapes increase spin velocity to greatly increase centrifugal forces on the particles, thereby more efficiently separating the particles from the air stream.

It is still yet another feature of this invention to provide a circular plate, vertical in the primary centrifuge collector and horizontal in the secondary centrifuge collector, which is mounted opposite the outlets thereof. It is an advantage of the foregoing feature that re-entrained collected particulates otherwise generated by the cyclonic vortices are prevented.

It is yet still another feature of this invention that the number of secondary centrifuge collector units is variable. It is an advantage of the foregoing feature that the cleaning apparatus of this invention can be adapted for any magnitude of fluid flow to be cleaned, as well as for fluid flows having differing amounts and types of particulates or other impurities to be separated therefrom.

It is yet still another feature that embodiments of this invention may be made from steel alloys or other heat-resisting materials. It is an advantage of the foregoing feature that the cleaning assembly of this invention can operate continuously at extreme temperatures, without becoming plugged by removed particulates at efficiencies equal to, or surpassing, bag houses of the prior art.

These and other objects, features, and advantages of this invention will become apparent from the description which follows, when considered in view of the accompanying drawings.

It is understood that the above-described figures are only illustrative of the present invention and are not contemplated to limit the scope thereof.

DETAILED DESCRIPTION

Any references to such relative terms as vertical and horizontal or inner and outer are intended for convenience of description and are not intended to limit the present invention or its components to any one positional or spatial orientation. All dimensions of the components in the attached figures may vary with a potential design and the intended use of an embodiment of the invention without departing from the scope of the invention.

Referring toFIG. 1, one embodiment of an assembly for removing particulates from a fluid stream of this invention is indicated generally at100and includes a primary centrifuge collector102, a secondary centrifuge collector104, an induced draft fan106, a particulate disposal assembly108, respective first and second duct assemblies110and112, and a support frame114.

Referring now toFIGS. 1,2, and3, the primary centrifuge collector102of this embodiment may include an outer housing120forming an ingress such as an inlet121, an egress such as outlet cylinder122, and structure for removing particulates separated from the incoming fluid flow in the primary centrifuge dust collector, such as an auger assembly124. In this embodiment, the inlet121is unitarily (or otherwise integrally) formed from the housing120. However, a person of ordinary skill in the art would readily recognize that such inlet could be formed separately, then attached to the remainder of the housing120. Additionally, the embodiment depicted has an access opening (not shown), which is covered by an access plate126. The primary centrifuge collector102may optionally include a generally curved guide plate128with attached particle reflexive130and maintained in place by a housing plate weld and a reflexive plate132. The reflexive plate132may be generally aligned with the outlet cylinder122as shown by line133. The embodiment of the outlet cylinder122shown includes an inner cone frustum134and an extension136.

By way of illustration and not limitation, as viewed inFIG. 2the primary centrifuge collector102may have a depth of 72 inches, as viewed along lines133or138(excluding the extension represented by the auger assembly124). As viewed byFIG. 3, the primary centrifuge collector102may have a height of 88¼ inches as measured along line140and a width of 72 inches as measured along line133. The inlet121may be rectangular with exemplary dimensions of 12 inches by 36 inches. The generally circular portion of the primary centrifuge collector102may have a radius of 36 inches and the extension136of the outlet cylinder122may have a radius of 36 inches. The generally linear portion of the inlet121coinciding with the periphery of the housing120may have a length of 36 inches. The lower portions of the housing120may taper to a tangent142or144, the lower portions having a length of 37⅞ inches. The extension136of the outlet cylinder122may have an inner diameter of 17⅝ inches, the extension136being bonded to the inner cone frustum134at one end thereof. Accordingly, the inner cone frustum134tapers from an inner diameter of 17⅝ inches to 12 inches. The inner frustum134and the extension136may both have lengths of 18 inches, thereby combining for a total length of 36 inches for the outlet cylinder122. In the embodiment depicted, the reflexive plate132is generally circular, having a diameter coinciding with that of the inner frustum cone134, e.g., 12 inches. The guide plate128may have a length of 72 inches and a width 40¾ inches. When configured as depicted inFIG. 3, the guide plate128may extend along an arc of 70 degrees, at a radius of 33¾ inches, so as to define gaps146and148between the guide plate128and the housing120. A person of ordinary skill in the art will readily recognize that these dimensions may be altered as needed, e.g., to accommodate fluid (air) streams of varying magnitudes.

As shown in FIGS.1and4-7, a first embodiment of the secondary centrifuge collector104includes a plurality, e.g., four secondary centrifuge collector units160. However, it should be recognized tat any number of such secondary centrifuge collector units may be present, the exact number depending upon factors such as the magnitude of fluid stream to be cleaned and the nature and concentration of the particulates present within the fluid stream. As best viewed inFIGS. 5 and 7, the exterior of the secondary centrifuge collector104has an upper panel162and a tapered lower hopper164extending from the upper panel162. The lower hopper164tapers to a spout166. The spout166may include a structure to expel particulates separated from the fluid stream during operation. One suitable such structure depicted inFIG. 7ais a trickle valve176, which includes a pair of paddles152disposed within the spout166. The paddles152are attached and operated by pivots180. Each pivot180may terminate in a handle182, which may extend generally perpendicularly to the pivot180.

As best viewed inFIGS. 8-11, each of the secondary centrifuge collector units160(FIG. 7) has an outer cylinder190and an outlet element192. The outer cylinder190and outlet element192are assembled within the secondary centrifuge collector unit160using respective upper and lower plates194and196(FIG. 23) so that a plurality of secondary centrifuge collector units160are present therein. The outer cylinder190(FIG. 17) includes a cylindrical member200, flange202, reflexive plate204, bar206, and optional handles208(FIG. 9). The flange202is bonded to the cylindrical member200(e.g., by welds) and defines a concentric opening209. The opening209adjoins a cavity210defined in the cylindrical member200. The plate204is attached to the bar206, e.g., by welds, and aligns with the outlet element192as shown by its relation to the line211inFIGS. 9 and 11. The bar206, in turn, is attached (e.g., by welds) to a lower periphery of the cylindrical member200, so as to support the plate204.

InFIGS. 10-11may be seen details of the outlet element192, which includes a cylindrical member220, a flange222, optional handles224, and swirl vanes226. The cylindrical member220includes a cylindrical element230terminating in a frustum cone232having a terminal opening233. The flange222defines an opening234, which adjoins a cavity236defined in the cylindrical member220. As best seen inFIGS. 12-14, the swirl vanes226are attached to the cylindrical member220. Alternatively, the swirl vanes could be attached to an inner surface of the cylindrical member200of the outer cylinder190. Sixteen swirl vanes, deployed every 22½ degrees, are present in the embodiment depicted. However, a person of ordinary skill in the art will recognize that more or fewer swirl vanes may be present in other embodiments depending on such factors as the magnitude of the fluid flow to be cleaned, the amount of particulates to be separated, the dimensions of the outer cylinder and outlet element, and the pressures exerted by the fluid flow within the system of this invention. The swirl vanes236are configured so as to define a downward spiral during operation, for example and as shown inFIG. 12, having a radius of 5 11/16 inches at curve240, a radius of 9½ inches at curve242, a rollup of about 70 degrees and a three inch radius between lines244and246. Additionally and as best viewed inFIG. 13, an arc of 70 degrees may extend between points248and250, the remainder of the swirl claim226being generally planar in configuration. As seen inFIG. 14, the swirl vane226is attached, e.g., by welding, to the cylindrical member220.

As depicted inFIGS. 15-18, in assembling the outer cylinder190and outlet element192, the outer cylinder190is first lowered into place and attached to the lower plate196. The outlet element192is then lowered into place and attached to the upper plate194, e.g., using connectors such as bolts254.

By way of illustration and not limitation, the cylindrical member200of the outer cylinder190may have an outer diameter of 16 inches and a height of 43 inches. The flange202may have a radius of about 11 inches, with an inner opening of about 16 inches. The reflexive plate204may have a diameter of about five inches. The outlet element192may have a length of about 32 inches and an outer diameter of about 10 inches. The frustum cone232may be about eight inches in length and taper from an inner diameter of about 10 inches to about five inches. The flange222may have an outer radius of about 11 inches and have a concentric opening about 10 inches in diameter. The secondary centrifuge collector104depicted inFIG. 1has a height of 11 feet 9½ inches (excluding the spout166) and a width and length of four feet. When assembled as described above, the upper and lower plates are about 24⅞ inches spaced apart when the outer cylinder190and outlet element192are fixed into position.

Referring toFIGS. 19 and 20, another embodiment of the secondary centrifuge collector of this invention is indicated generally at260, wherein the auger108is formed integrally with the outer housing262of this secondary centrifuge collector. The spout166extends proximate the exit end of the auger unit108. In the secondary centrifuge collector260, as in the secondary centrifuge collector104, all four secondary centrifuge collector units160empty into a single auger108as enabled by a single tapering lower hopper264.

Referring toFIGS. 21 and 22yet another embodiment of the secondary centrifuge collector of this invention is shown at270, in which the outer housing272has a doubly tapering lower hopper274. The lower hopper274enables two of the secondary centrifuge collector units162empty into each portion of the lower hopper274. A person of ordinary skill in the art will readily recognize that other configurations of the secondary centrifuge collector of this invention may be suitable for other embodiments having a plurality of secondary centrifuge collector units.

Referring again toFIG. 1, the induced draft fan106, rotated by an electric motor276in this embodiment, is depicted. In the embodiment shown, the draft fan106induces negative pressure to draw air, or other fluid to be cleaned, through the assembly of this invention. By way of illustration and not limitation, the system depicted and described herein would be capable of cleaning between about 12,000 and 15,000 cubic feet of air per minute thus, the draft fan106would be able to convey between about 12,000 and 15,000 cubic feet of air per minute at a negative pressure of between about 3 inches water gage and 6 inches water gage. It is alternately recognized that a fluid flow induced by a positive pressure (e.g., by a fan or equivalent positioned upstream from the assembly of this invention) might be suitable for other embodiments of this invention.

The particulate disposal assembly108depicted inFIG. 1has a housing280enclosing an auger screw282. The auger screw282is rotated by a drive assembly284. While an auger is shown, other equivalent mechanisms (e.g., conveyor belt, gravitationally dumped hoppers) for disposing of separated particulates may be suitable for other embodiments.

The first and second duct assemblies110and112conduct fluids (e.g., air) being cleaned between the primary centrifuge collector and secondary centrifuge collector and between the secondary centrifuge collector and the draft fan, respectively. The confirmation and makeup of these assemblies will depend upon how the primary and secondary centrifuge collectors and induction fan are positioned. Inner dimensions of 13⅝ inches×48 inches has been found to be suitable for the embodiment depicted. However, a person of ordinary skill in the art will readily recognize that other dimensions are suitable for other embodiments conveying, e.g., differing amounts of fluids at differing pressures and particulate loads.

The support frame114depicted inFIG. 1includes a chassis290, stands292, and wheel assemblies294. The support frame114may be made from materials dimensioned to operably support the weight of the assembly of this invention during transport and operation. Additionally, the support frame used should be capable of imparting sufficient stability so that it will not shift or become unstable due to vibrations arising from operation. While a portable unit is depicted, a person of ordinary skill in the art will recognize that the assembly for removing particles from fluid streams of this invention can be assembled in a stationary configuration. Additionally, the components of the assembly of this invention could be shipped and assembled at sites in modules.

Sheet and tubular metals, such as steel or aluminum are envisioned as suitable materials for certain embodiments of this invention. However, a person of ordinary skill in the art will recognize that certain components may be made from synthetic resins. Suitable synthetic resins for components such as the duct assemblies and secondary centrifuge collectors include polyethylene, polypropylene, and polytetrafluoroethylene. However, a person of ordinary skill in the art will readily recognize that other synthetic resins may be suitable for a given embodiment of this invention. Other suitable synthetic resins may be found in the Handbook of Plastics, Elastomers, and Composites, Charles A. Harper, Editor in Chief, Third Edition, McGraw-Hill, N.Y., 1996, hereby incorporated by reference.

Referring again toFIG. 1, during operation the induced draft fan106, via an induced negative pressure, draws a fluid to be cleaned, such as air containing particulates from a hot asphalt mix plant, cement plant, foundry, coal fired boiler, or the like, into the primary centrifuge collector102as indicated by arrow300. The fluid flow enters the primary centrifuge collector102via the inlet121, wherein a first portion of the particulates are removed. Upon entering the primary centrifuge collector102, the fluid stream forms an outer vortex302, which is bounded by the primary centrifuge collector housing120. Upon reaching the end of the primary centrifuge collector housing120, the direction of the fluid stream is then reversed and develops into an inner vortex304spiraling toward, and entering, the cone frustum attached to the primary centrifuge collector outlet cylinder122. The centrifugal forces exerted upon particulates in the fluid stream force the particulates out of the vortices302and304and against the housing120. For example heavier particulates are forced from the vortex302and lighter particulates are forced from the vortex304. The particulates then are gravitationally conveyed downwardly into the particulate disposal assembly108, where they are removed. In place of the primary centrifuge collector102, a vertical primary centrifuge known to those of ordinary skill in the art may be used in certain embodiments of this invention.

Referring toFIGS. 24 and 25, one suitable embodiment of a vertical primary centrifuge is depicted generally at350which may be present in place of, or in addition to, the primary centrifuge collector102. The embodiment of the vertical primary centrifuge350depicted includes an outer housing assembly352and an outlet assembly354. The outer housing assembly352has an inlet358, a roof359, a cylindrical element360, a conical element362, a spout364, and a reflexive plate366. The inlet358receives the fluid flow from which particulates are to be removed and conducts the fluid flow into the structure constituted by roof359, the cylindrical element360and conical element362. The conical element362tapers down to the spout364. The spout364may include the trickle valve176, or some other equivalent structure to empty separated particulates. The reflexive plate366is attached to a lower portion of the conical element362, e.g., by welding and may be supported by a bar, as described above with respect to the bar206present in the outer cylinder190of the secondary centrifuge collector unit160. The outlet assembly354includes a cylindrical element370, which terminates in a frustum372. The cylindrical element370is attached to the egress373. The cylindrical element370and frustum372are aligned with the reflexive plate366, as can be seen by their relationships to the axis374.

By way of illustration and not limitation, suitable dimensions for the vertical primary centrifuge350include an inlet35810 inches×22 inches, a cylindrical element360with a diameter of 60 inches and a height of 30 inches, a conical element with a height of 59½ inches and362tapering from an upper diameter of 60 inches to a lower diameter of 8 inches, a spout364with cross sectional dimensions of 6 inches×6 inches, and a reflexive plate with a diameter of 14 inches. The cylindrical element370may have a height of 27 inches and an outer diameter of 28⅞ inches. The frustum372may have a height of 14 inches and may taper from an outer diameter of 28⅞ inches to 16 inches. The egress373may have a height of 14 inches and cross sectional dimensions of 14×14 inches. These dimensions may vary depending on factors such as the magnitude of fluid to be treated, the pressures of such fluid within the assembly of this invention, and the magnitude and types of particulates present in the fluid which are to be removed. A person of ordinary skill in the art will readily recognize that other structures for performing the functions of the primary centrifuge collector102and/or vertical primary centrifuge350may be present in place of, or in addition to, these structures. Non-limiting examples of these structures which may be present in place of, or in addition to, the primary centrifuge collector102and/or vertical primary centrifuge350include cyclone separators (e.g., hydroclones) known to the art.

In operation, the fluid flow from which a first portion of the particulates are to be removed enters the inlet358and is directed into the interior of the vertical primary centrifuge housing assembly352bounded by the roof359, cylindrical element360and conical element362. The position and orientation of the inlet358directs the fluid flow into a spiraling outer vortex380, thereby removing larger particulates from the fluid flow. The fluid in the outer vortex380then impinges the reflexive plate366, thereby reversing the direction of the fluid flow into an inner vortex382. The higher velocity, hence energy, of the fluid flow within the inner vortex382removes a further portion of smaller particulates from the fluid flow. From the inner vortex382, the fluid flow enters the frustum372, then the cylindrical element370. From the cylindrical element370, the fluid flow is transmitted into the egress373. From the egress373, the fluid flow enters the first duct assembly110, which conducts the fluid flow to the secondary centrifuge collector100for this invention.

In place of, or in addition to, the vertical primary centrifuge350, primary centrifuge collector102, and secondary centrifuge collector104, other fluid flow cleaning devices may be present. Suitable examples of such fluid flow cleaning devices are disclosed and described in U.S. Pat. No. 7,070,637 to Zhang, issued 4 Jul. 2006, U.S. Pat. No. 4,309,283 to Vikio et al., issued 5 Jan. 1982, U.S. Pat. No. 7,159,723 to Hilpert et al., issued 9 Jan. 2007, and U.S. Pat. No. 7,179,314 to Conrad et al., issued 20 Feb. 2007, each hereby incorporated by reference.

From the primary centrifuge collector102(or vertical primary centrifuge350), the partially cleaned fluid stream is conveyed to the secondary centrifuge collector by the first duct assembly110as indicated by the arrow306. Alternatively, the primary and secondary centrifuge collectors102and104(or equivalents) can be directly connected. If so, all or most of the first duct assembly110would not be present.

As depicted inFIG. 23, the first duct assembly110delivers the fluid flow to the secondary centrifuge collector104(or other secondary centrifuge collector embodiments), where the fluid flow enters one of the secondary centrifuge collector units160as depicted by arrow308(FIG. 23) where a second portion of the particulates are removed. When entering the secondary centrifuge collector unit160, the fluid flow enters via the flange opening209into the cylindrical member cavity210, where the fluid flow impinges the swirl vanes226. Impinging the swirl vanes226configures the fluid flow into an outer vortex308. The fluid flow is conveyed downwardly within the outer vortex308until it impinges the reflexive plate204. After impinging the reflexive plate204, the direction of fluid flow is reversed to form an inner vortex310. The fluid flow then is conveyed by the inner vortex into the cavity236of the secondary centrifuge collector unit outlet element192, from where it is conveyed from the secondary centrifuge collector unit160via the opening233(FIG. 17), then from the entire secondary centrifuge collector104into the second duct assembly112. While inside the secondary centrifuge collector units160the centrifugal forces resulting from the vortices308and310further separate particulates from the fluid stream. In certain embodiments a centrifugal force of 9000 times the force of gravity is exerted upon the particulates within the inner vortex310to remove most or essentially all particulates from the fluid stream. The separated particulates fall downwardly, as indicated by the arrow's314, and are removed from the secondary centrifuge collector104by the particulate disposal assembly108(FIG. 1).

Referring yet again toFIG. 1, the duct assembly112conveys the cleaned fluid stream to the induced draft fan106as shown by arrow. The induced draft fan106then conveys the fluid stream into the environmental atmosphere as shown by arrow316.

A person of ordinary skill in the art will readily appreciate that individual components shown on various embodiments of the present invention are interchangeable to some extent and may be added or interchanged on other embodiments without departing from the spirit and scope of this invention.

Because numerous modifications of this invention may be made without departing from the spirit thereof, the scope of the invention is not to be limited to the embodiments illustrated and described. Rather, the scope of the invention is to be determined by the appended claims and their equivalents.