Abstract:
Filter assembly, particularly for handling liquids at elevated temperatures. There is disclosed a filter assembly wherein the headers supplying filter liquid to the filter units and receiving filtrate therefrom are arranged in a first zone, all the filter units are arranged in a second zone, and at least some of the actuators for the backwash controlling valves extend outwardly of and away from both of said zones to avoid the heat associated with said zones. A heat shield may then be positioned between said valve actuators and the rest of the filter assembly, which heat shield may, if desired, be one wall of a heat retaining box enclosing the headers and filter cylinders.

Description:
FIELD OF THE INVENTION 
     The invention relates to a backwashing control for a gang of filters, and particularly to a control especially adapted for use with filters handling liquids at elevated temperatures wherein said control is removed from the zone of elevated temperatures. 
     BACKGROUND OF THE INVENTION 
     In the filtering of various types of liquids in chemical plants, pulp mills, refineries or similar plants, it is common to use a filtering system involving a plurality of individual filter units positioned close together and provided with automatic control means for effecting backwashing. In the course of normal operation of said backwashing control means, same often becomes for one reason or another progressively less efficient, or may even suffer complete breakdown, and when this happens the filter unit to which such control means is connected fails to backwash properly. Where the filter is one of a group thereof, such breakdown is often not noticed immediately and the improper operation may continue for a substantial period of time before discovery. 
     One particular example of such problem occurs where the filters are handling liquid at an elevated temperature, often of the order of 400°-550°F. in frequently encountered refinery usages, and hence the filter housings and conduits associated therewith are heated to such levels and radiate heat accordingly. In presently standard constructions, the backwash controlling valves and actuators therefor are positioned closely adjacent, often between, the filter unit components, such as between the filter housings and the associated conduits, and are accordingly subjected to such radiated heat. Where, as is usual, the actuators are pneumatic, they utilize pistons with sealing means therein which sealing means are elastomeric and usually subject to rapid deterioration when subjected to temperatures as above mentioned, especially for prolonged periods. Thus, under normal operating conditions of such filters, these seals may, and often do, rapidly deteriorate. This may in some circumstances result merely in the loss of power needed to fully shift the valve but in other cases it can result in binding of the actuator piston and a consequent complete failure to effect backwashing. In such cases, even though the replacement of a piston seal, usually a simple O-ring, is of itself a relatively minor and inexpensive job, the heat to which the filters and conduits are subjected as above stated requires substantial cooling of the unit before a workman can under existing safety regulations approach same for repair and/or replacement of the defective mechanism. Since it may often take from 8 to 10 hours for the filter and system to which it is connected to cool sufficiently to permit such access by workmen, it is apparent that a relatively minor repair job can keep the filters and thereby often an entire processing line inactive for a considerable period of time. This is obviously costly and it has long been recognized as a disadvantage of the equipment available up to the present. 
     In certain types of otherwise highly satisfactory equipment the problem has been particularly acute in that the filter units are placed in at least two rows, each row being on opposite sides of a central header and the valves being directly above and/or below such central header. Such positioning of the valves places the controllers between and somewhat behind the filter units and this, while operationally convenient, makes same difficult of access for repair and/or replacement regardless of temperature considerations. However, when the equipment is hot as above outlined, such access becomes even more difficult and the cooling above mentioned must be substantial. 
     The problem is further intensified where a heat retaining box is placed around the filter unit but such box is nevertheless often used for heat conservation reasons. 
     Thus, since the filters are necessary to the systems in which they are used and no solution was known to the problem of actuator repair as above described, said problem and the difficulties arising therefrom have been tolerated. 
     Some attempts have been made to obtain the benefits of such heat retaining box without the damage above mentioned arising from overheating of the actuators by wrapping insulative material around the conduits and valves and, if desired, even around the filter units but leaving the actuators projecting therefrom. This works reasonably well and is hence often used in place of the heat retaining box. This, however, generates substantial expense in both the original application of said insulative material and in the maintenance thereof. Further, where such insulative wrapping is used it renders all parts difficult of access and hence creates further expense in the proper maintenance of the equipment. 
     Other attempts to meet this problem have involved wrapping the actuators with insulative material in order to protect them from the heat of the adjacent filters and conduits, particularly if said latter remain unwrapped. This, however, is likewise undesirable for the same reasons as above set forth, namely expense of wrapping, inconvenience and expense in maintenance, said latter particularly including the inconvenience and expense of obtaining access to the actuators for repair or maintenance thereof. 
     A still further suggestion for meeting the foregoing outlined problems has been to replace the normally used actuators by other control devices which would be capable of withstanding high temperature operating conditions. However, this is often not economically desirable or commercially available. Instead the normally used actuators are inexpensive and, excepting for the problems created by high temperature operating conditions as above outlined, are reliable in operation and simple to repair when needed. 
     Therefore, again, in spite of the problems above-described, the necessity of the filters in question to numerous industrial systems has impelled the continued use of such actuators and for lack of apparent solution said problems and resulting difficulties have been tolerated for several years. 
     Accordingly, the major objects of the invention include: 
     1. To provide an organizational pattern for a filter assembly which will maintain the effectiveness of currently known filter assemblies but which will permit the actuators for the backwash controlling valves to be placed in an accessible position for service and/or replacement regardless of whether the filter unit operates at an elevated temperature and regardless of the cause of the need for such service and/or replacement. 
     2. To provide apparatus, as aforesaid, in which, where the filter operates at an elevated temperature, the placement of said valve actuators can be outside of the heated zone surrounding the filter unit and the associated conduits. 
     3. To provide apparatus, as aforesaid, wherein such improved accessibility of the valves will not involve extended or complex mechanical linkage between the actuator and the valve. 
     4. To provide apparatus, as aforesaid, which will be particularly adaptable to the use of air energized valve actuators. 
     5. To provide apparatus, as aforesaid, which will not materially, if at all, increase the manufacturing cost of a filter assembly over that previously experienced. 
     Other objects and purposes of the invention will be apparent to persons acquainted with apparatus of this general type upon reading the following specification and inspecting the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIG. 1 is a side broken view of a filter assembly embodying the invention. 
     FIG. 2 is a top view of the apparatus shown in FIG. 1. 
     FIG. 3 is an end view of the apparatus shown in FIG. 1, showing also in section a heat retaining box which is in some instances placed around said filter unit. 
     FIG. 4 is a central section of a valve and actuator unit showing the details of a conventional valve and valve controlling unit utilized in the assembly of the invention. 
     FIG. 5 is a broken side view of a different filter construction embodying the invention with the heat retaining box removed. 
     FIG. 6 is an end view of the apparatus shown in FIG. 5 showing also in section the location of the heat retaining box if and when same is used. 
    
    
     SUMMARY OF THE INVENTION 
     By rearranging the filter units and placing all of same generally in one zone with respect to the headers from which they are supplied and into which they discharge, it becomes possible to offset all of the valve controllers into a different zone with respect to the headers and to operate same effectively without extensive mechanical linkage. Thus, the wall of a heat retaining box may be positioned adjacent said headers which box may then encompass said headers and the filter units but the actuators are outside of said box and shielded from the heat therewithin. Accordingly, there is less deterioration of the seals utilized in said actuators and by the same token same can be inspected more readily and removed for repair and/or replacement more readily. 
     DETAILED DESCRIPTION 
     Turning now to the drawings in more detail for one specific embodiment of this concept, there is shown a supporting frame structure 1 comprising a plurality of uprights 2 connected by at least one longitudinal member 3. Suitable brace members are provided for the better support of the filter assembly, if desired, in any manner convenient, such as those shown at 6. Additional or alternate frame structure may be provided as desired. Extending longitudinally and centrally through the filter assembly is a conduit 7, usually the inlet conduit, provided with the usual flange means 8 for connecting to supply means and directly thereabove is an outlet conduit 9 extending similarly through the assembly and provided with suitable means as the flange 11 for connecting to a filtrate receiving system. 
     Assuming for the present that the backwashing operation is to take place with a liquid other than the filtrate, there is provided a backwash supply conduit 12 parallel with and spaced above the outlet conduit 9. 
     A drain (backwash disposal) conduit 13 is provided adjacent the bottom of the assembly spaced from, below and parallel with the inlet conduit 7. 
     A short pipe 16 connects the backwash supply conduit 12 through an on-off valve 17 to a further short pipe 18 which is connected through a T-connection 19, hereinafter further referred to, and thence a short pipe 21 and a further on-off valve 22 to and into the outlet conduit 9. 
     Similarly, a short pipe 31 connects the drain conduit 13 through an on-off valve 32 and the further short pipe 33 to a T-connection 34 (hereinafter further mentioned). Said T-connection is then connected through another short pipe 36 and an on-off valve 37 to and into the inlet conduit 7. Each of said valves 32, 37, 17 and 22 is conventional and one preferred form is shown in FIG. 4. Assuming same for example to be the valve 17, there is shown a valve body 41 containing the conventional ports 42 and 43 and a valve core 44 rotatable for on-off positioning in a conventional manner by a rotatable stem 46. 
     Connected to said stem 46 is a conventional valve actuator 47 which in this embodiment is of an air-energized type. In such embodiment a pair of oppositely directed, but suitably cooperating, pistons 48 and 49 are connected to opposite ends of a pin 51 which pin extends through an actuator stem 52. Movement of said pistons toward said stem act on opposite ends of the pin 51 to effect rotation of the stem 52 and thereby, in a manner already known, to effect rotation of the valve stem 46 to position the valve core as desired. The return for said pistons may be conventional, as by reversal of the air pressure or by resilient means as desired. 
     It will be recognized that the effective operation of said actuator is dependent upon the effectiveness of the sealing of the piston therein, which is in turn dependent on the effectiveness of resilient O-rings of which one is indicated at 53. It is the often accelerated, and frequently erratic and unpredictable, breakdown of these O-rings when the actuator is operated under high temperature conditions that brings about the erratic and unsatisfactory operation of the devices of the prior art. 
     A protective casing 54, usually mounted as shown here on the cover of the valve housing, is normally provided for protecting the valve stem, the actuator stem and the connection therebetween. 
     All of the foregoing, except the exact positioning of the valve actuators, is conventional, well known to the art and forms no part of the present invention. 
     Turning now to the means by which the above-described problems have been satisfactorily solved, there is in this embodiment provided from the T-connection 19 a conduit 61 extending therefrom in one direction only and same connects to a header 62 (FIG. 1). Said header connects at each end to the upper end of a pair of filter units 63 and 64 which are mounted side-by-side and on the same side of the conduits 7 and 9. The lower ends of said filter units 63 and 64 connect through a further header 66 to a connector 67 which in turn connects to the T-connection 34. 
     Returning now to the valves 17, 22, 37 and 32, same are here positioned so that their respective stems are perpendicular to the plane defined by the longitudinal centerlines of the conduits 12, 7, 9 and 13. Said valve stems, actuator stems and the protective housing 54 are all chosen of sufficient length to extend beyond a plane defined by the common tangent to the surfaces of the conduits 7 and 9 remote from the above-mentioned filters. 
     Thus, the placement of the pairs of filters on one side of the conduits 7 and 9 makes it possible for the valve stems to project directly to the other side thereof and to be easily accessible. Thus, a protective wall 71 may be positioned between the actuator 47 and the remaining components of the filter system for heat control purposes as above described, but without subjecting said actuators to such heat or without inhibiting their accessibility for repair or replacement. Normally, such wall 71 will be part of a heat retention box 73 surrounding the entire filter device. 
     Connectors such as the one indicated at 72 may be provided between the valve actuators in a conventional manner to insure simultaneous operation of respective pairs of valves, such as the valves 17 and 22. 
     Although the foregoing description has been directed toward the filter unit 63 and 64 and the conduits, valves and valve actuators directly associated therewith, it will be recognized that each of the other filter units shown, together with their respective connections, valves and valve actuators, will be identical to the components above-described and hence no individual description of these further units is required. It will be further recognized that a given filter assembly may be provided with as many pairs of filters and their respective connections, valves and valve actuators as desired for given installations. 
     If it is desired in a given case to dispense with the heat retaining box 71 and to use instead insulative wrapping for the several conduits and connections which are provided for a given filter assembly, the filter units and their respective valve actuators may still be advantageously arranged as shown without interfering with the operation, inspection, repair and/or replacement of any of the valve actuators used therewith. 
     It will be further recognized that where it is acceptable to use the filtrate for the backwash material, the conduit 12, valve 17 and connecting pieces immediately associated therewith will be discarded (or alternatively, the valve 17 positioned in a permanently closed position) and the backwash effected in a known manner by pressurizing the outlet conduit 9 and reversing the valves 32 and 37. 
     In FIGS. 5 and 6 there is illustrated a somewhat modified filter construction which still embodies the substance of the present invention although with a somewhat different arrangement of the specific parts thereof. The parts of the filter which are the same or functionally the same as those appearing in FIGS. 1-4 are identified with the same numerals as appearing in FIGS. 1-4 with the letter &#34;A&#34; associated therewith. The description given above with respect to FIGS. 1-4 will for the most part apply also to FIGS. 5 and 6 and does not need to be repeated. However, it should be here noted that this filter is intended to utilize the discharge therefrom for backwashing and hence there is no conduit shown herein corresponding to the conduit 12 in FIGS. 1-4 but same could be added, if desired, in the same manner as in FIGS. 1-4 without departure from the scope of the invention. Further, it will be noted that in FIGS. 5 and 6, the single valve 37 between a filter pair and the inlet conduit 7 of FIGS. 1-4 is represented in FIGS. 5 and 6 by two independent valves 37A-1 and 37A-2 which normally function simultaneously with each other in the same manner as valve 37 above mentioned but which provide for enlarging the capacity of the connection between the inlet conduit 7A and the filters without the necessity for larger and hence more expensive piping. It will be noted, however, that the valve 32A is serially connected to valves 37A-1 and 37A-2 between the inlet conduit 7A and the drain conduit 13A by means of the conduit 33A, fitting 70 T-connections 34A-1 and 34A-2, and conduits 36A-1 and 36A-2. This corresponds to the serial connection of the valves 37 and 32 above-described and the filters in FIGS. 5 and 6 are connected to a point between said valves in functionally the same manner as the filters in the embodiment of FIGS. 1-4. It will be further noted that in FIGS. 1-4 the conduits occupy a first zone which is of essentially vertically oriented and rectangular shape, with the filters occupying a second generally rectangular, vertically oriented, zone on one side thereof and the valve actuators occupy a third vertically oriented, generally rectangular, zone on the opposite side thereof. Constrastingly, in FIGS. 5 and 6 the conduits occupy a generally L-shaped first zone, the filters occupy a vertically oriented, generally rectangular, second zone in the notch of but spaced from the L-zone and the actuators occupy two separate zones on either side of and sufficiently spaced from both said first and second zones to enable a heat shield 71A or heat retaining wall to be positioned between said actuators and the adjacent one of both said first and second zones. 
     It will be recognized by extension of the foregoing that a variety of further specific arrangements of the filters and conduits can be provided in addition to those shown herein which will incorporate at least some of the concepts and resulting advantages of the present invention. For example, said conduits, or some of them, may be placed in a nonparallel relationship with respect to one or more of the other conduits but still having the centerlines lie within a single vertical plane, or other identifiable zone, in the manner shown in the present drawings. 
     Further possible arrangements involve positioning one or more of said conduits in other specific patterns with respect to each other but still within a sufficiently cohesive zone, and a zone distinguishable and spaced from that occupied by the filters, that the actuators can project out therefrom and away from both said zones without the necessity of using excessively long connecting means with consequent high engineering and maintenance costs. 
     Thus, while specific embodiments of the invention have been shown and/or described for illustrative purposes, it will be recognized that other modifications may be made therein without departure from the scope of the hereinafter appended claims and said modifications are fully contemplated excepting as the claims may expressly require otherwise.