DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0041] The present invention overcomes the deficiencies in the related art in a filter basket assembly having an extended surface area which is generally indicated at 110 in FIG. 2. The assembly 110 includes a vessel, generally indicated at 112, having an inlet 114, an outlet 116 and a filter chamber 118 defined therebetween. In the preferred embodiment, the filter chamber 118 is elongated and substantially cylindrical in shape. However, those having ordinary skill in the art will appreciate that the filter chamber 118 may be any geometric shape without departing from the scope of the invention. A cover 120 is removably mounted to the otherwise open top 122 of the vessel 112. A basket assembly, generally indicated at 124, is removably received in the chamber 118 through the top 122 of the vessel 112 and may be supported by any number of support mechanisms. For example, the basket assembly 124 may be supported by a support extending from the wall of the filter chamber 118; by suspending the basket assembly 124 from the upper lip at the top 122 of the vessel 112; or by a support which spaces the basket assembly 124 from the bottom 123 of the vessel 112. However and in the preferred embodiment, the basket assembly 124 is supported by a peripheral flange 126 extending radially inward from the inner side wall of the chamber 118 near the inlet 114. The basket assembly 124 has a diameter which is less than the diameter of the chamber 118 and together they define an outer annular flow passage 128. While the vessel 112 illustrated in the figures supports a single basket assembly 124, those having ordinary skill in the art will appreciate that the present invention is not limited to single basket vessels and may be employed with vessels supporting multiple basket assemblies and filters.

[0042] The basket assembly 124 will be described in greater detail with reference to FIGS. 3-7 of the drawings. Referring specifically to FIGS. 3, 4, 4A, 5 and 5A, the basket assembly 124 includes an outer substantially cylindrical, permeable member 130 and an inner substantially cylindrical, permeable member 132. However, those having ordinary skill in the art will appreciate that the inner and outer permeable members 130, 132 may take any geometric shape without departing from the scope of this invention. The outer permeable member 130 defines a pair of opposed, open ends 131, 133. The inner member 132 has one permeable arcuate end 134 and a flange 135 located at the opposite open end of the inner permeable member 132. The inner member 132 has a diameter which is less than the diameter of the outer member 130 and is received in the outer member 130 such that the flange 135 may be connected to the open end 133 as by welding with a continuous weld bead or any other suitable means as shown in FIGS. 6-7. The other open end 131 of the outer permeable member 130 is adapted to be received and supported by the peripheral flange 126 extending radially inward from the inner side wall of the chamber 118. Together, the inner and outer permeable members 132, 130, respectively, define an annular space 136 therebetween and an inner flow path 138 interior of the annular space 136. The inner and outer permeable members 132, 130 may be made of a permeable metal or plastic including stainless steel, wire mesh or any other suitable structure which allows fluid to pass therethrough but which is structurally capable of supporting a filter bag as will be described in greater detail below. In the preferred embodiment, the inner and outer permeable members 130, 132 are made of a 304 grade passivated stainless steel.

[0043] The assembly 124 may also employ a carriage, generally indicated at 140 in FIGS. 8 and 8A. In the preferred embodiment, the carriage 140 is elongated and substantially cylindrical in shape. However, those having ordinary skill in the art will appreciate that the carriage 140 may be any geometric shape without departing from the scope of the invention. Furthermore the carriage may take any shape which effectively accommodates the bag-type filter as described in greater detail below. The carriage 140 has a pair of opposed open ends 141, 143 with a plurality of annularly spaced rods 145 extending therebetween. In the preferred embodiment, the rods 145 are ¼ inch in diameter and are made of 304 grade stainless steel. Because of the structure of its preferred embodiment and its appearance as illustrated in FIG. 8, the carriage 140 is often referred to as a “wire” carriage.

[0044] The wire carriage 140 is a tool used to insert the extended bag-type filter into the basket assembly 124. One embodiment of the extended bag-type filter of the present invention is generally indicated at 142 in FIGS. 9-10 and another embodiment is generally indicated at 242 in FIGS. 13-14. In the first preferred embodiment, the filter 142 is substantially cylindrical in shape and has a first portion 144 having a first, larger diameter, a second portion 146 having a second, reduced diameter and a transition portion 148 disposed therebetween. The transition portion 148 may be formed merely by a reduction in the diameter of the extended area filter. Alternatively, the transition portion 148 may take the form of a circular piece of filter material which defines an inner diameter 152 and an outer diameter 154. The transition portion 148 is attached to the first portion 144 of the filter 142 at the outer diameter 154 of the transition portion 148. Similarly, the transition portion 148 is also attached to the second portion 146 of the filter 142 at the inner diameter 152 of the transition portion 148. The filter 142 also has an arcuate closed end 150 and an open end 151 defined by an annular ring which is located opposite the closed end 150 when the filter 142 is in and extended position as illustrated in FIG. 9. On the other hand, the arcuate closed end 150 is positioned adjacent the open end 151 when the filter is in its assembled position as illustrated in FIG. 10. The filter element 142 may be disposable, non-reusable and may be manufactured from needled felt, meshes or any other material which provides a mechanical straining effect on the fluid. In the preferred embodiment, the filter 142 is made of a micron rated fabric which may provide, for example, six to seven square feet of filtration surface area in the approximate proportional size depicted in these Figures. However, those having ordinary skill in the art will appreciate that the area of the filtration surface of any given filter 142 will vary with the size of the vessel 112 and basket assembly 124.

[0045] As shown in FIGS. 11-12 in connection with the first embodiment of the filter 142, the second portion 146 is received within the inner diameter defined by the cylindrical wire carriage 140. The first portion 144 of the bag-type filter 142 is then folded over the outer diameter of the wire carriage 140. The transition portion 148 facilitates this step and bridges one annular open end 141 of the wire carriage 140 between its inner and outer diameter.

[0046] On the other hand, the wire carriage 140 may also be used in conjunction with an alternative, second embodiment of the extended, bag-type filter generally indicated at 242 in FIGS. 13 and 13A. The alternate embodiment of the filter 242 enjoys the advantage that it is easy to manufacture. Like that of the first embodiment, in the second preferred embodiment, the filter 242 is substantially cylindrical in shape and has an outer, first portion 244, shown in FIG. 14, having a first, larger diameter; a second portion 246, shown in FIG. 15, having a second, reduced diameter; and a transition portion 248, generally shown in FIGS. 16-17, disposed therebetween. The first portion 244 includes a pair of opposed, open ends 245, 247. The second portion 246 includes one open end 249 and an arcuate, closed end 250. The open end 245 of the first portion 244 is defined by an annular ring which is positioned about the arcuate, closed end 250 when the filter 242 is in its assembled position as illustrated in FIG. 13.

[0047] Referring specifically to FIGS. 16-17, the transition portion 248 is substantially U-shaped in cross-section having an annular, inner flange 252; an annular, outer flange 254; and an arcuate, bridge portion 256 formed therebetween. On end 247 of the first portion 244 is attached to the outer flange 254. Similarly, one end 249 of the second portion 246 is attached to the inner flange 252 by any manner, including, but not limited to, gluing, heat setting, sewing, crimping, or any mechanical or chemical method known in the art or yet to be discovered. The transition portion 248 has a relatively high stiffness or rigidity relative to the filter 242 and is preferably one piece and made from molded polyethylene. However, the transition portion 248 may be formed in a number of ways including, for example, by two L-shaped members bonded together.

[0048] Those having ordinary skill in the art will recognize that the transition portion 248 may be formed in many ways. For example, the first portion 244 and the second portion 246 may be attached in a number of ways such as by sewing, glueing, laser welding or otherwise heat sealed, or crimped together. In any event, the filter element 242 is disposable and non-reusable and may be manufactured from needled felt, meshes, or any other material which provides a mechanical straining effect on the fluid. In the preferred embodiment, the filter 242 is made of a micron rated fabric which may provide, for example six to seven square feet of filtration surface area in the approximate proportional size depicted in these figures. However, those having ordinary skill in the art will appreciate that the area of the filtration surface of any given filter 242 will vary with the size of the vessel 112 and of the basket assembly 124.

[0049] As shown in FIGS. 18-19, the second portion 246 is received within the inner diameter defined by the cylindrical wire carriage 140. The first portion 244 of the bag-type filter 242 is received over the outer diameter of the wire carriage 140. The transition portion 248 bridges one annular open end 141 of the wire carriage 140 between its inner and outer diameter.

[0050] As shown in FIGS. 20-21, the wire carriage 140 supporting the filter 142,242 of either embodiment is then flipped 180° such that it may be received within the annular space 136 formed between the inner 132 and outer 130 members of the basket assembly 124 and such that the closed end 150,250 of the filter is cooperatively engaged by the permeable arcuate end 134 of the inner member 132. The basket assembly 124 is then inserted into the chamber 118 of the vessel 112 as shown in FIG. 2. The wire carriage 140 may then be removed. Alternatively, the wire carriage 140 may be used solely to insert the filter 142, 242 into the basket assembly 124. However, those having ordinary skill in the art will appreciate that the wire carriage is not essential and that the filter 142,242 could be properly fitted about the basket assembly 124 without it.

[0051] As best shown in FIG. 2, dirty fluid shown shaded in FIG. 2 enters the vessel 112 through the inlet 114 as indicated by the arrows A. The dirty fluid then enters the annular space 136 between the inner and outer permeable members 132, 130 of the basket assembly 124 as indicated by the arrows B. In most operational environments, the dirty fluid will fill the annular space 136 until it is at or above the permeable, arcuate end 134 of the inner member 132. The dirty fluid then passes through the basket assembly 124 through the filters 142, 242 and into either the outer, annular flow passage 128 or the inner flow path 138 as indicated by the arrows C. Clean fluid then exits the filter chamber 118 through the outlet 116, as indicated by the arrows D.

[0052] The dirty fluid passes through the filter 142,242 just once, but the effective surface area of the filter 142,242 has been doubled through the use of a bag-type filter 142,242 having first portions 144,244 and second portions 146,246 supported by the wire carriage 140 about both the inner and outer baskets 132, 130. Because of its extended filter surface area, the present invention may be employed to at least double the useful life of the bag-type filter without any substantial increase in costs while, at the same decreasing the pressure drop (ΔP) of the fluid through the vessel. More specifically, beta site testing of the filter assembly of the present invention has revealed that an extended area bag type filter of the present invention having approximately double the surface area over a comparable conventional filter subjected to the same flow rate results in three to four times the useful filter life over a conventional filter. This is because the impact velocity of the solid particles in the dirty fluid against the extended area filter is reduced by approximately ½ when compared to conventional filter assemblies. In addition, use of the extended area filter assembly of the present invention reduces the initial pressure drop (ΔP) by approximately ½ when compared to the initial pressure drop across conventional filter assemblies. Alternatively, the size of the vessel may be reduced by employing the filter assembly of the present invention while maintaining the same respective useful life of the filter. Smaller vessels reduce the plant space required for these filtering systems. Finally, the extended area bag-type filter of the present invention is inexpensive, cost-efficient and is easy to use in the field.

[0053] The invention has been described in an illustrative manner. It is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the invention are possible in light of the above teachings. Therefore, the invention may be practiced other than as specifically described.