Abstract:
A filter for use in filtering solids from liquids and/or gases is provided with an elongated tube having a filter media wrapped along its length, around its perimeter, and the filter media is renewed, either on a continuous basis or on a timed basis by activating a pump to rotate a filter media take-up roll contained within the interior of the porous tube, which then causes the filter media to move around the exterior of the porous tube. The porous tube may be ceramic, hard plastic or a perforated metallic material, or may be a screen which underlies the filter media.

Description:
[0001]     It is well known to use filters within the interior of reactors or other closed vessels such as closed pressure vessels. By way of example, U.S. Pat. No. 6,428,593; U.S. Pat. No. 6,413,422; U.S. Pat. No. 5,948,257 and U.S. Pat. No. 5,849,375 are patents directed to candle filters known in the art. The invention is not limited to candle filters, but can be used with other filters, including but not being limited to cartridge filters, dust filters and the like. It is well known that the candle filters are typically made from a porous ceramic material which are designed so that, in the event of failure, the filters do not fail catastrophically.  
         [0002]     Filters in this art are oftentimes self-supporting and are shaped like long tubes, with one open end and one closed end. Such filters are typically fastened within an enclosure, which is divided into clean and dirty sides such that the fluid to be filtered traverses from the dirty side to the clean side of the enclosure by passing through the filter. The fluid typically flows from the outside to the inside of the filter, thus providing a fluid exiting from the open end thereof having an acceptable level of particles.  
         [0003]     It is also known in the prior art that such filters can and do use various filter media to filter out the various particles residing in the fluid stream. It is also well known that such filter media tend to clog up and have to be replaced periodically. With the devices known in the prior art for use with closed vessels, for example, with reactors, the reactor has to first be shut down and then opened up and the filter media replaced. This is a timely, expensive operation to shut the reactor down and clean it up and various prior art patents have attempted to remedy the problem. For example, there have been attempts to back flush the filter media but these attempts have been usually somewhat unsuccessful. Such a back flush system is described in U.S. Pat. No. 5,948,257, with the back flush system sometimes referred to as “reverse pressurization”. There is also described in U.S. Pat. No. 5,948,257 the known process of using metal tubes instead of ceramic tubes to make such tubes less susceptible to the pressures encountered with the back flush process. Although metal tubes can be used with the present invention, there is described in U.S. Pat. No. 5,948,257 problems which have been encountered when using metal tubes instead of ceramic tubes.  
         [0004]     It is also known to use filters which are renewed in open vessel configurations such as air filters used with air conditioning units and with furnace units, such as, for example, as shown in U.S. Pat. No. 2,853,155; U.S. Pat. No. 2,881,861; U.S. Pat. No. 3,985,528; U.S. Pat. No. 3,276,191; U.S. Pat. No. 4,054,521; U.S. Pat. No. 4,470,833; U.S. Pat. No. 4,221,576 and U.S. Pat. No. 6,152,998. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]      FIG. 1  is an elevated view, partly in cross section, of a filter according to the present invention;  
         [0006]      FIG. 2  is a top plan, diagrammatic view taken along the sectional line  2 - 2 , illustrated in  FIG. 1 ;  
         [0007]      FIG. 3  is a second view of the cross-sectional view illustrated in  FIG. 2  but having the filter media in place in accordance with the invention over the plurality of rollers illustrated in  FIGS. 1, 2  and  3 ;  
         [0008]      FIG. 4  illustrates a cross-sectional view of an alternative embodiment of the present invention in which the tube for the filter is circular in cross-section;  
         [0009]      FIG. 5  illustrates an elevated view, partly in cross section, of an alternative embodiment of the rollers used with the filters according to the present invention;  
         [0010]      FIG. 6  illustrates, in block diagram, a system for rotating the take-up roll for the moving filter media according to the present invention;  
         [0011]      FIG. 7  illustrates, schematically, the use of a plurality of filters within a closed vessel as contemplated by the invention;  
         [0012]      FIG. 8  is an elevated view, partly in cross-section, of an alternative embodiment of the present invention;  
         [0013]      FIG. 9  is a top plan view taken along the section line  9 - 9  illustrated in  FIG. 8 ;  
         [0014]      FIG. 10  is an elevated view of a segment of filter media according to the present invention;  
         [0015]      FIG. 11  is an elevated view, in cross-section, taken along the section line  11 - 11  illustrated in  FIG. 10 ;  
         [0016]      FIG. 12  is a diagrammatic view of a static seal used with the filter according to the present invention;  
         [0017]      FIG. 13  is a diagrammatic view of a spring-loaded seal used in accordance with the present invention;  
         [0018]      FIG. 14  is a diagrammatic view of a triangular seal used in accordance with the present invention; and  
         [0019]      FIG. 15  is a diagrammatic view of an alternative embodiment of a seal which can be used with the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0020]     Referring now to the drawings in more detail, especially to  FIGS. 1, 2  and  3 , there is illustrated an elevated view of a filter according to the present invention, with  FIG. 2  being a cross-sectional, diagrammatic view taken along the sectional lines  2 - 2  illustrated in  FIG. 1 . It should be appreciated that in  FIG. 1 , the filter  10  is essentially an octagonally shaped device but which has only seven sides  12 ,  14 ,  16 ,  18 ,  20 ,  22  and  24 , with the sides  12  and  24  being slightly longer than the other five sides and having a cutout section  26  between the sides  12  and  24  which holds a source of filter media  28  and a take-up roll  30  for holding the spent filter media, as contemplated by this invention. It should be appreciated that the cut-out section  26  in the preferred embodiment runs along the entire length of filter  10 , between its top end and bottom end, to allow the filter media to pass in and out of the filter  10 , all the way from the filter media containment area  27  to the external surface or surfaces of the filter  10 . The filter media containment area  27  is merely a space located within the interior of the porous tube which is large enough to contain the filter source roll and the filter media take-up roll. Although not illustrated, the filter media containment area  27  will typically have a pair of spindles having spines made up with the interior opening of the rolls, which can be fabricated as ratcheting devices, if desired, to prevent rotation except in one direction, if desired. It does not matter whether the roll  28  is the source or the take-up toll and likewise for the roll  30 . One of the rolls is the source and the other is the take-up. As illustrated in  FIG. 2 , a plurality of rollers are located, respectively, at the respective apexes at which the respective sides of the filter come together. For example, the roller  32  is located at the meeting point of the sides  12  and  14 . In a similar way, the roller  34  is at the junction of the sides  14  and  16 , and the roller  36  is at the junction of sides  16  and  18 . Roller  38  is located between sides  18  and  20  and a roller  40  is located at the junction of the sides  20  and  22 . A roller  42  is located at the junction of the sides  22  and  24 . A pair of rollers  44  and  46  are located on opposite sides of the opening  26  leading to the containment area  27  within which the filter media source  28  and the take-up roll  30  are located.  
         [0021]     In using the device illustrated in  FIG. 2 , the filter media  28  is hand rolled from the source  28  to extend past the rollers  46 ,  32 ,  34 ,  36 ,  38 ,  40 ,  42  and  44  and then wound onto the take-up roll  30 .  
         [0022]     Referring now to  FIG. 3 , there is a diagrammatic view of a filter media  31  having been hand rolled over the rollers as above discussed with respect to  FIG. 2 . Because  FIG. 2  and  FIG. 3  are merely diagrammatic views, the filter media source  28  and take-up rolls  30  are oriented slightly different, but the function of the filter media source roll and the take-up roll is identical in  FIGS. 2 and 3 .  
         [0023]     Referring again back to  FIG. 1 , the elevated view of the filter  10 , according to the present invention, illustrates the rollers  34 ,  36 ,  38  and  40  as being at the upper end of the filter  10 . A second set of such rollers are illustrated at the lower end of the filter  10  and numbered as rollers  54 ,  56 ,  58  and  60 . It should be appreciated that rollers  54 ,  56 ,  58  and  60  are the only ones which would be visible from the view as illustrated in  FIG. 1 , but there are four corresponding rollers  42 ,  44 ,  46  and  32  located on the blind side of filter  10 , as illustrated in  FIGS. 2 and 3 , and also four other rollers (not illustrated) on the blind side of the upper end of the filter  10 .  
         [0024]     A third set of rollers, which are optional, are located in the center portion of the filter  10  and are identified as being rollers  74 ,  76 ,  78  and  80  which would also have counterparts in the middle section of the filter  10 , but which are one the blind side of the filter and are thus not illustrated.  
         [0025]     A plate  90  is located at the top end of the filter  10  and is used to be bolted onto a second plate  92  which is connected to the housing  94 . A center hole (not illustrated) passes through the housing  94  to allow the clean fluid product to pass from the interior  100  of the filter  10  (see  FIG. 3 ) and pass through the housing  94  and the outlet pipe  102 , which passes through a baffle plate  104  into the collection area  106 , which then passes through the outlet port  108 . The plates  92  and  90  are bolted together by a plurality of bolts  110 ,  112  and  114  and by other bolts (not illustrated) on the blind side of the housing  94 .  
         [0026]     In the operation of the filter  10 , a “dirty” gas or other fluid containing solid particles is passed into an inlet port  107  into a closed vessel  120  containing the filter  10 . It should be appreciated that the body of filter  10  typically is a porous ceramic material closed at its lower end  11  and opens at its upper end leading through the housing at the outlet pipe  102  to allow the “clean” fluid to be gathered into the collection area  106 . As with almost any filter system, as the dirty fluid passes through the filter media and through the porous ceramic body, the filter media will eventually clog up and lose its efficiency. With the conventional filter, this would have required the shutdown of the process and the removal of filter  10  to wrap the body of the filter  10  with new filter media, all of which is not only very time consuming but can be dangerous to the personnel involved with cleaning out the vessel  120 .  
         [0027]      FIG. 4  illustrates an alternative embodiment of the present invention in which the tube  200  for the filter is circular in cross-section.  FIG. 4  also shows a plurality of rollers  202 ,  204 ,  206 ,  208 ,  210 ,  212 ,  214  and  216 . Within the interior of the tube  200 , there is illustrated the take-up roll  230  and the filter media roll  228 . The manual turning of the roll  230  causes the filter media to be stretched over the rollers  202 - 216 , but once the process starts, the fluid flowing through the sidewall of the porous ceramic tube  200  will cause the filter media  201  to be pushed into contact with the exterior surface walls of the tube  200 . The overall effect of the device shown in  FIG. 4  mimics the effect of the device illustrated in  FIG. 3  except for the filter media not making as intimate of contact with the round walls as does the filter media illustrated in  FIG. 3  with respect to the flat walls.  
         [0028]      FIG. 5  illustrates an alternative embodiment of the present invention which uses rollers  334 ,  336 ,  338  and  340  and additional rollers which are located on the blind side of the filter  300 . The embodiment of  FIG. 5  operates essentially the same as the embodiment of  FIG. 1 , but instead of having two or three sets of rollers, the embodiment utilizes eight containment rollers which pass from the top of the filter  300  to the lower extreme of the filter  300 , although there may be more or less than eight rollers depending upon the filter geometry. In all other respects, the embodiment of  FIG. 5  is the same as the embodiment of  FIG. 1 .  
         [0029]     Referring now to  FIG. 6 , the filter illustrated in  FIG. 5  is illustrated as having in dotted line an illustration of the take-up roll  330 , which is functionally equivalent to take-up roll  30  in  FIG. 3 . In order to rotate the take-up roll  330 , its lower end is mounted on a drive member  350  which can take several known forms such as having gear teeth or the like that when driven, cause the take-up roll  330  to rotate. A hydraulic pump  360  is driven by a motor  370 , which may be pneumatic, electric or hydraulic. The pump  360  has a hydraulic line  390  which causes the drive member  350  to rotate, and return line  380  which returns the hydraulic fluid to the pump  360 .  
         [0030]     Alternatively, the drive mechanism  350 , and the associated components  350 ,  380 ,  390 ,  360 ,  370  and  400  can be located at the upper end  351  of the filter  300  to cause the take-up roll  330  to rotate, for example, as illustrated in  FIG. 8 .  
         [0031]     The filter media, which is advanced in these various embodiments of the invention, can be so advanced in a variety of ways. The pump  360  and the motor  370  can be activated by a timer  400 , which can be set to rotate the filter media around the exterior of the filter once every so many days, for example, once every ten days, every twenty days, or whatever number of days, or even hours, which may be required to insure that the filter media surrounding the filter stays relatively clean. Alternatively, the motor and pump can be set to cause the drive member  350  to rotate continuously, but more slowly, to keep the filter media constantly renewing itself. Alternatively, the take-up roll can be rotated by a hand crank (not illustrated) to advance the filter media. By monitoring the differential pressure across the filter media, the operator knows when to rotate the hand crank.  
         [0032]     Referring now to  FIG. 7 , there is illustrated the use of a plurality of filters within the confines of a closed vessel  501 , such as the vessel  120  illustrated in  FIG. 1 . Although  FIG. 7  illustrates only the use of four such filters identified as filters  502 ,  504 ,  506  and  508 , it is fairly commonplace to use twenty-six such filters in a single reactor which is used for producing tetrahydrofuran, commonly referred to as “THF”.  
         [0033]     For each illustration, filters  502 ,  504 ,  506  and  508  are illustrated in  FIG. 7  without having the rollers of  FIGS. 1, 2 ,  3 ,  4 ,  5  or  6 , but one or more of such rollers and their equivalents are intended to be used with each such filter when practicing the invention.  
         [0034]     THF is manufactured from furan, a heterocyclic compound. THF is derived either from the catalytic hydrogenation of furan with nickel catalysts or from the acid-catalyzed dehydration of 1,4-Butanediol. THF is moderately toxic by ingestion and inhalation, but is somewhat more dangerous as a flammable fire risk since exposure of THF to air can cause combustion.  
         [0035]     One of the processes which can be used with the apparatus and methods of the present invention involves the reaction of the catalytic hydrogenation of furan with a nickel catalyst, but because of the fire risk, it is better to leave the vessel closed as long as possible. One of the ways of achieving that result is to allow the filters to be renewing their filter media without opening up the closed vessel, which is achieved by causing the filter media to be renewed around the exterior of the filter, as presently disclosed.  
         [0036]     It should be appreciated that the rollers which are utilized as described herein, whether being the sets of rollers as described in  FIG. 1  or the elongated rollers which are described in respect to  FIGS. 5 , and  6 , all function to reduce the friction between the filter media which is being moved around the exterior of the filter, and the exterior wall or walls of the filter itself. Whether the filter tube is itself circular or has a discreet number of flat walls, such as are illustrated in  FIGS. 2 and 3 , the flat wall variety of the filter can have any number of such walls other than having the seven or eight walls contemplated by  FIGS. 2 and 3 . The filter tube can be a triangle in cross section, a square, a rectangle, or have five, six or even nine or more walls, if desired. It is important, however, that each of the points at which there is located a meeting of two flat walls, that there be a roller assembly to reduce friction.  
         [0037]     It should be appreciated that although the preferred embodiment contemplates the use of ceramic as material for the porous tube used with the filter of the present invention, such tubes can also be made from hard plastic, for example, high density urethane or polyurethane, or from various metals such as steel, aluminum, stainless steel and the like, and may be made porous by perforations or slots fabricated therein as in well-known in the art of filters. Such tubes can also be made of various screen materials, for example from metallic screens which can be used underneath the filter media.  
         [0038]     Although the preferred embodiment contemplates the gas or liquid being filtered to pass from the outside of the filter to the inside of the filter, the process works quite well having a liquid or gas pass from the inside of the filter to the outside of the filter, a process that still allows the filter media to be renewed, as described herein.  
         [0039]     Almost any woven, cast, or thermally formed filter media can be employed in the filter according to the present invention. Examples include:  
                                       1)   Polypropylene       2)   Polyester       3)   Cotton       4)   Rayon       5)   Nomex       6)   Teflon       7)   Stainless Mesh       8)   Fiberglass       9)   Nylon       10)   Kevlar       11)   Combination of items 1-10, above.                  
 
         [0040]     Referring now to  FIG. 8 , there is illustrated an alternative embodiment of the present invention which shows a filter  618  according to the present invention, but which is attached to the ceiling  619  of a closed vessel  602  which can be used for various functions, including that of being a chemical reactor. The vessel  602  can also contain dirty liquids which have been injected into the “in” portal  604  of the vessel  602 . It should be noted that in this embodiment, the vessel has an “out” portal  606  which makes use of gravity to evacuate the fluid, for example, a clean liquid which is passed through the filter  618  suspended in the pressure vessel  602 .  
         [0041]     In the embodiment of  FIG. 8 , the pump  608 , a motor  610  and a timer  612  are used at the top portion of the filter  618 , which uses a pair of hydraulic lines  614  and  616  to rotate the take-up roll  702  illustrated in  FIG. 9  hereinafter.  
         [0042]     Referring now to  FIG. 9 , which is a cross-sectional view taken along section lines  9 - 9 , illustrated in  FIG. 8 , there is illustrated a take-up roll  702  and a filter media source roll  704  which together enable the filter media  706  to be renewed as needed, and as further described herein with respect to the other embodiments of the invention. The filter  618 , illustrated in  FIGS. 8 and 9 , uses rollers  620 ,  622 ,  624 ,  626 ,  627 ,  628 ,  629  and  631  to reduce friction as the filter media is being renewed, all as set forth herein before.  
         [0043]      FIG. 9  also illustrates an annular member  630  which is non-porous and which runs the length of the filter  618  illustrated in  FIG. 8 . The annular area between the member  630  and the porous member  632  is referred to hereinafter as an annular clean fluid collection area  640 . To some extent, the annular clean fluid collection area  640  also includes any space between the porous member  632  and the filter media  706 . The purpose of the annular clean fluid collection area  640  is a further attempt to prevent clear fluid from being contaminated by the dirty fluid which is external to the filter media  706 .  
         [0044]     The annular clean fluid collection area  640  is connected to conduit  607  which thus allows the clean fluid to pass from the annular clean fluid collection area  640  from the “out” protal  606  into whatever storage area or conduit is desired (not illustrated).  
         [0045]     Referring now to  FIG. 10 , there is illustrated a partial, elevated view of the filter media  632  which can encircle the filter illustrated as filter  618  in  FIG. 9 . Attached to the top portion of filter media  632  is a strip  633  of the sealing material. A similar strip of such sealing material  635  is attached along the length of filter media  632 , and which is attached to filter media  632  on the lower extreme of the filter media  632 . As illustrated in  FIG. 11 , there is a cross-sectional view taken along section lines  11 - 11  illustrated in  FIG. 10  which shows the manner in which strips  633  and  635  attach to filter media  632 . If desired, the strips  633  and  635  mat be thermally fused to the filter media  632 . The strips  633  and  635  may be fabricated of various materials, including Viton and Teflon. The filter media  632  may be of various materials as set forth herein above.  
         [0046]     Referring now to  FIG. 12 , there is schematically illustrated the rollers  800  and  802  which are located at the entrance to the filter through which the filter media passes from the supply roll  804  and which after encircling the filter comes back to the take-up roll  806 . The embodiment of  FIG. 12  is an alternative embodiment of the embodiment illustrated in  FIGS. 10 and 11 , but which can be used in combination with the embodiment of  FIGS. 10 and 11 .  FIG. 12  includes a static seal which runs along the length of the filter, such as the filter  618  of  FIG. 9 . The seal material  808  may be any material of choice such that a seal is provided between the filter media  632  and the roller  800  and between the roller  802  and the filter media  632 . Because of the configuration of static seal  808 , which runs the length of filter  618 , the dirty fluid cannot enter into the center portion of the filter housing containing the take-up roll  806  and the supply roll  804 .  
         [0047]     Referring now to  FIG. 13 , there is illustrated another apparatus for sealing the entrance through the rollers  800  and  802 , but instead of having a static seal  808 , there is illustrated a spring loaded seal  810  which generates a tighter seal between filter media  632  and the seal  810 .  
         [0048]      FIG. 14  illustrates yet another seal  900  which is fabricated in the shape of a triangle. It should be appreciated that the triangle seal  900  runs the entire length of the filter such as the filter  618 . The leading apex of the triangle  900  has attached thereto an arm  902  which can be used to tighten the triangular configuration within the entrance of the filter body and may be locked in place after tightening as desired.  
         [0049]      FIG. 15  is an alternative embodiment of a sealing member  904  which can be pulled down tight to seal against a static seal  906  to accomplish similar results as does the triangular seal  900  of  FIG. 14 .  
         [0050]     Thus, there has been described and disclosed herein various sealing configurations for sealing the entrance from the exterior of the filter  618  into the interior of the filter  618  containing the filter media rolls  704  and  702  of  FIG. 9 .