Abstract:
A bag filter arrangement for being arranged in a bag filter holder, comprising a bag filter having an end portion encompassing an open end of the bag filter, a bag filter seal for sealing against the bag filter holder, the bag filter seal being arranged to hold the bag filter, the bag filter seal comprising a bag filter facing surface, and wherein the bag filter seal comprises a recess on the bag filter facing surface, the recess being arranged to receive the open end portion of the bag filter.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The invention is related to Swedish patent application no. 1551260-1, filed on 1 Oct. 2015, which is incorporated herein by reference. 
       TECHNICAL FIELD 
       [0002]    The present invention relates to a bag filter arrangement for being arranged in a bag filter holder. 
       BACKGROUND ART 
       [0003]    In the food, pharmaceutical and chemical industry, dried and powderized products or intermediate powderized products need to be separated from other undesired components before being packaged or delivered to further processes downstream. A powderized product or intermediate powderized product may henceforth be known as powder product. A known method is to use bag filter downstream of a silo or a hopper which hold and/or store the powder product, and filter the powder product using the bag filter. The powder product is thus fed into the bag filter which is made of different types of material and pore sizes for retaining the desired powder product. The undesired components are thus allowed to pass through the bag filter. The undesired component may be air, i.e. the bag filter may be arranged for separating air and the powder products. The powder product may be fed through the bag filter at high speed utilizing overpressure on the upstream side of the bag filter, or by utilizing a vacuum on the downstream side of the bag filter. Alternatively, the bag filter may be configured to allow the desired powder product to pass the bag filter, while retaining the undesired components. In either case, it is important to seal the edges of the bag filter to a bag filter e.g. the silo or hopper in order to prevent the powder product or undesired components from bypassing the bag filter. This is typically solved using some sort of seal between the bag filter and the bag filter holder. 
         [0004]    The seal may be moulded, or use felt or other materials for sealing against a bag filter holder. However, the mentioned options may not provide sufficient attachment to the bag filter itself, or may not be able to combine with certain materials used for the bag filters. 
         [0005]    There is thus a need for improving the state of the art to provide a bag filter arrangement which at least partly solves these problems. 
       SUMMARY 
       [0006]    It is an object to improve the current state of the art, to solve at least some of the above problems. These and other objects are achieved by a bag filter arrangement. 
         [0007]    According to a first aspect a bag filter arrangement for being arranged in a bag filter holder is provided. The bag filter arrangement comprises: a bag filter having an end portion encompassing an open end of the bag filter; a bag filter seal for sealing against the bag filter holder, the bag filter seal being arranged to hold the bag filter, the bag filter seal comprising a bag filter facing surface; and wherein the bag filter seal comprises a recess on the bag filter facing surface, the recess being arranged to receive the open end portion of the bag filter. 
         [0008]    The bag filter arrangement is based on the realization that by providing a recess on a bag filter facing surface, which recess is arranged to receive the open end portion of the bag filter. An improved attachment between the bag filter seal and bag filter may be provided. Further, the bag filter may be attached to the bag filter seal after the manufacturing of the bag filter seal, which enables the bag filter seal and the bag filter to comprise material which were not able to be combine previously. The bag filter arrangement provides an improved seal between the bag filter and the bag filter holder. Further, a bag filter arrangement as described herein may be manufactured at a low cost. 
         [0009]    A bag filter holder may be understood as a silo or hopper containing the powder product to be filtered by the bag filter. The bag filter holder may comprises a plate having a hole or opening the general shape of the bag filter seal. 
         [0010]    In at least one exemplary embodiment, the bag filter seal comprises an opening, the opening being fluidly connected to an inside of the bag filter. The opening is facing the open end of the bag filter. The opening enables powder to be filtered to enter the bag filter via the opening in the seal. 
         [0011]    In at least one exemplary embodiment, the bag filter seal comprises an inner surface extending from the opening to an inside of the bag filter, and wherein the bag filter seal comprises an outer surface extending from the opening to an outside of the bag filter. The shortest path along the inner surface to the bag filter may be shorter than the shortest path along the outer surface to the bag filter. The outer surface may at least partly be facing away from the inside of the bag filter. The inner surface may at least partly be facing an inside of the bag filter. 
         [0012]    In at least one exemplary embodiment, the outer surface comprises a sealing protrusion arranged to seal against the bag filter holder. In at least one exemplary embodiment, the sealing protrusion is a first sealing protrusion and wherein the outer surface further comprises a second sealing protrusion arranged to seal against the bag filter holder. Sealing protrusion(s) may improve the sealing between the bag filter seal and the bag filter holder. 
         [0013]    In at least one exemplary embodiment, an end portion of the recess is located in proximity second protrusion. For example, the second sealing protrusion may be arranged radially outwardly of the end portion recess. This may provide an increased stiffness of the seal in the proximity of the end portion of the recess and the second sealing protrusion. 
         [0014]    In at least one exemplary embodiment, bag filter seal further comprises a nook arranged between the first and the second sealing protrusions. The nook may be construed as a corner, or a concave surface between the first and second sealing protrusions. 
         [0015]    In at least one exemplary embodiment, the first sealing protrusion, the nook, and the second sealing protrusion together forms a sealing portion of the bag filter seal, the sealing portion being arranged to seal against the bag filter holder. The sealing portion should the be understood to be arranged to be a receiving portion for an end portion of the bag filter holder which mates with the sealing portion. The first sealing protrusion, the nook, and the second sealing protrusion may provide a snap-lock such that the first and second sealing protrusion snap over edges of an end portion of the bag filter holder. 
         [0016]    In at least one exemplary embodiment, the bag filter seal is made of at least one of the following materials: Silicone, PVC (polyvinyl chloride), Rubber. Compared to the prior art which did not provide a freedom of choice in the seal materials, the above materials are more compatible with the powderized food product which may be used with the bag filter. The bag filter seal may be made using the techniques of vulcanisation or extrusion. 
         [0017]    In at least one exemplary embodiment, the bag filter comprises a PTFE (polytetrafluoroethylene) membrane, or polyester with or without a PTFE membrane. The bag filter arrangement enables the use of PTFE membranes for the bag filters, and the use of polyester with or without PTFE membranes. 
         [0018]    In at least one exemplary embodiment, wherein, in the recess, the end portion of the bag filter is attached to the bag filter seal by at least one row of stitches or adhesive means. The bag filter arrangement, due to the materials which may be used, enables the use of at least one row of stitches to attach the bag filter to the bag filter seal. The row of stitches should be interpreted as a row of stitches around the circumference of the seal, which thus attaches the bag filter in the recess. More than one row of stitches may be used, such as two rows of stitches. The adhesive may be any known and suitable adhesive. 
         [0019]    In at least one exemplary embodiment, the bag filter seal extends at least in a radial direction from a center axis of the bag filter arrangement. A central axis of the bag filter arrangement may be understood as a central axis of the bag filter, which passes through the opening of the bag filter seal. 
         [0020]    In at least one exemplary embodiment, the seal comprises a top portion and a bottom portion, the top portion having a radial extension greater than a radial extension of the bottom portion, and wherein the bottom portion at least partly encompasses the recess. The top portion may be construed as a support portion which, in use, rests on, and is thus supported by, the bag filter holder. The first sealing protrusion may be positioned on the top portion, the nook may be positioned between the top and bottom portions, and the second sealing protrusion may be positioned on the bottom portion facing radially outwards. 
         [0021]    Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to “a/an/the [element, device, component, means, step, etc.]” are to be interpreted openly as referring to at least one instance of said element, device, component, means, step, etc., unless explicitly stated otherwise. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    The above objects, as well as additional objects, features and advantages of the bag filter arrangement, will be more fully appreciated by reference to the following illustrative and non-limiting detailed description of preferred embodiments of the present invention, when taken in conjunction with the accompanying drawings, wherein: 
           [0023]      FIG. 1  is a cross-sectional view of a bag filter arrangement in accordance with an exemplary embodiment; 
           [0024]      FIG. 2  is a cross-sectional view of a bag filter arrangement in accordance with an exemplary embodiment; 
           [0025]      FIG. 3 a    is a perspective view of an exemplary embodiment. 
           [0026]      FIG. 3 b    is a side view of an exemplary embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    In the present detailed description, embodiments of a bag filter arrangement are mainly discussed with reference to views only showing components and portions being relevant in relation to various embodiments of the bag filter arrangement. It should be noted that this by no means limits the scope of the bag filter arrangement, which is also applicable in other circumstances for instance with other types or variants of bag filter arrangements and processes than the embodiments shown in the appended drawings. Further, that specific features are mentioned in connection to an embodiment of the bag filter arrangement does not mean that those components cannot be used to an advantage together with other embodiments of the bag filter arrangement. 
         [0028]    The bag filter arrangement is suitable for being installed in an industrial food production facility, or pharmaceutical production facility, or chemical production facility, for filtering powder products. When a powder product is transported through the bag filter seal, and bag filter, undesired particles with a small size are allowed to pass the bag filter. The bag filter thus collects the desired powder products. Another mode of operation is of course that the powder product is allowed to pass through the bag filter, the bag filter being configured to allow the powder food product to pass through, and the bag filter collects the undesired particles. The powder product may be fed using pneumatic means and possible an overpressure, or by utilizing an under pressure, e.g. partial vacuum such as less than 1 kilo Pascal, on the downstream side of the bag filter arrangement. The powder product is thus filtered and may be transferred to further processes downstream such as different treatments and/or packaging. The bag filter arranged may be used for either a round, e.g. circular bag filter arrangement or an elongated, e.g. a flattened, bag filter arrangement. An embodiment of a round bag filter arrangement  30  is shown in  FIG. 3 a   , and an elongated bag filter arrangement  40  is shown in  FIG. 3   b.    
         [0029]      FIG. 1  shows a cross-sectional view of a bag filter arrangement  10  in accordance with an exemplary embodiment. The bag filter arrangement  10  comprises a bag filter  20  and a bag filter seal  30 . The bag filter seal has a center axis B. The bag filter  20  and bag filter seal  30  extends in a radial direction from the center axis B. The bag filter seal  30  typically extends further in a radial direction than the bag filter  20 . Whereas the bag filter typically extends further in an axial direction along the center axis B than the bag filter seal  30 . 
         [0030]    The bag filter  20  has an open end portion  21  and a closed end portion  22  opposite the open end portion  21 . The closed end portion  22  may be closed by stitching or by using an adhesive. The bag filter  20  may comprise a PTFE membrane. For example, the bag filter  20  may be made of polyester with or without a PTFE membrane. The bag filter  20  may be made of any other known bag filter materials. The length of the bag filter  20 , seen as the vertical direction in  FIG. 1 , may be in the range of 500 mm to 1500 mm. 
         [0031]    The bag filter seal  30  comprises a recess  31  for receiving the open end portion  21  of the bag filter. The recess  31  is arranged on a bag filter facing surface  31 ′ of the bag filter seal  30 . The open end portion  21  may be attached in the recess  31  by either a row of stitches or by using an adhesive. Alternatively, both stitches and an adhesive may be used. The row of stitches may be a row of stitches around the circumference of the bag filter seal  30 . In exemplary embodiments, at least two rows of stitches may be used. When using more than one row of stitches, the rows of stitches are preferably spaced apart. The bag filter seal  30  may be made of silicone, PVC, or rubber. The length of the closed end portion  21  which is inserted in the recess  31  may be in the range of 10 mm to 40 mm. 
         [0032]    The bag filter seal  30  further comprises an opening  33  in the top of the bag filter seal which is fluidly connected to the open end  21  of the bag filter  20 . A powder product may be introduced into the bag filter  20  be being transported through the bag filter seal via the opening into the bag filter  20  in the direction indicated by the arrow A in  FIG. 1 . The width, e.g. the diameter if the opening  33  is circular, may be in the range of 20 mm to 40 mm. The width of the elongated opening  33  discussed with reference to  FIG. 3 b    may also be in the range of 20 mm to 40 mm. The bag filter seal  30  further comprises a sealing portion  34 . The sealing portion is arranged on the outside of the bag filter seal  30 . The sealing portion  34  is the portion of the bag filter seal  30  which, in use, seals the bag filter arrangement  10  against the bag filter holder (not shown) such that a powder product is prevented from bypassing the bag filter arrangement  10 . 
         [0033]      FIG. 2  shows an enlarged view the bag filter seal  30 . The bag filter seal  30  has an inner surface  35  and an outer surface  36 . Note that the path from where the opening begins, marked by  33 ′ in  FIG. 2 , is shorter along the inner surface  35  than along the outer surface  36 . This is because the outside, e.g. the outer surface  36 , of the bag filter seal  30  comprises a number of features for further improving the sealing effect between the bag filter seal  30  and a bag filter holder (not shown). 
         [0034]    The outer surface  36  of the bag filter seal  30  comprises a first sealing protrusion  37 . The first sealing protrusion  37  may be, and as shown in  FIG. 2 , arranged at the same height, being the vertical direction in  FIG. 2 , as the end of the recess  31 . Thereby, the stiffness of the bag filter seal  30  may be increased in proximity of the end of the recess and the first sealing protrusion  37 . The first sealing protrusion  37  may protrude substantially in a radial direction from the central axis B of the bag filter arrangement  10 . 
         [0035]    The outer surface  36  of the bag filter seal  30  further comprises a second sealing protrusion  38 . The second sealing protrusion  38  is arranged spaced apart from the first sealing protrusion  37 . The second sealing protrusion  38  may protrude substantially in an axial direction of the central axis B. In other words, the second sealing protrusion  38  may extend downwards as seen in  FIG. 2 . 
         [0036]    The outer surface  36  of the bag filter seal  30  further comprises a nook  39 . The nook  39  is arranged between and spaced apart from the first and second sealing protrusions  37 ,  38 . The nook  39  may also be construed as a corner located radially inwards, as seen from the central axis B, from the second sealing protrusion, and located axially upwards along the central axis B as seen in  FIG. 2 . 
         [0037]    The first sealing protrusion  37 , the second sealing protrusion  38 , and the nook  39  may be understood as the sealing portion  34  of the bag filter seal  30  which is arranged to seal against a bag filter holder (not shown). The sealing portion  34  may be arranged to snap lock, or at least improve the attached to the bag filter holder by being flexible and resilient. 
         [0038]    The bag filter seal  30  may alternatively be described as having a top portion  30   a  and a bottom portion  30   b.  The top portion has a greater radial extension than the bottom portion  30   b.  The bottom portion  30   b  comprises the recess  31  and the first sealing protrusion  37 . The bottom portion  30   b  at least partly encompasses the recess  31 . The top portion  30   a  comprises the second sealing protrusion  38 . The nook  39  is arranged between the top  30   a  and the bottom portion  30   b.    
         [0039]      FIG. 3 a    shows a perspective view of a round bag filter arrangement  110  according one embodiment. The round bag filter arrangement  110  comprises a bag filter  20  which has been inserted into a recess of the bag filter seal  30  and attached. The bag filter  20  and bag filter seal  30  are the same elements as described above in conjunction with  FIGS. 1 and 2 . A round bag filter arrangement  110  may typically only mounted vertically. 
         [0040]      FIG. 3 b    shows a perspective view of an elongated flat bag filter arrangement  210  according one embodiment. The flat bag filter arrangement  210  has an elongated cross section perpendicular to the direction of the center axis B. The elongated flat bag filter arrangement  210  comprises a bag filter  20  which has been inserted into a recess of the bag filter seal  30  and attached. The bag filter  20  and bag filter seal  30  are the same elements as described above in conjunction with  FIGS. 1 and 2 . An elongated flat bag filter arrangement as shown in  FIG. 3 b    may typically be mounted both vertically and horizontally. In order to mount the bag filter arrangement  210  horizontally, a rigid support structure may be inserted into the bag filter  20  through the opening in the bag filter seal  30 . 
         [0041]    It is of course understood that variations to the shown embodiment may be effected and still be within the scope of the invention described herein, for example the bag filter or bag filter seal may be made of other known materials. 
         [0042]    The skilled person realizes that a number of modifications of the embodiments described herein are possible without departing from the scope of the invention, which is defined in the appended claims.