Field of the application

The present disclosure relates to pressure filter apparatuses with a filling shoe, and to filling shoes. The present disclosure also relates to methods for updating and operating the pressure filter apparatus.

Background

A pressure filter apparatus is a device used in industrial separation processes to separate solids and liquids. One type of a pressure filter apparatus comprises a stack of plurality of filter elements, which are movable and can be opened to remove the filtered solids and to allow cleaning and maintenance of the apparatus. One specific type of a pressure filter apparatus is a horizontal pressure filter apparatus with vertical filter elements or plates. In such system the filter elements are suspended at horizontal support elements, such as support bars, and the filter elements can be moved along the support elements to open and close the stack of filter elements.

A filter element usually comprises a filter plate, which forms a recess at the centre of the plate, and a filter cloth which covers the recess. When two adjacent filter elements are moved together, the opposing recesses covered with the filter cloths define a filter chamber between them. To provide the material to be filtered, which is usually a suspension of solids, to the filter chamber, a channel through the filter elements is formed and a filter shoe is provided for conveying the material from the channel to each filter chamber. In many cases there is an aperture in the filter cloth for the channel and to which the filling shoe is installed. Such filling shoes may be plastic parts which have an aperture corresponding to the aperture in the filter cloth, and one or more channels allowing the material to be conveyed to the filter chamber. Such a structure however provides several drawbacks.

When the filling shoe is inserted in the filter cloth, this requires specific types of filter cloths with a designated aperture, which makes the filter cloths expensive and prone to damage and wear caused by mechanical forces directed to the aperture. Changing and/or installing the filling shoes is a slow and complicated process. In an apparatus having tens or even hundreds of filter elements it is a very time-consuming process. The positioning of the filling shoes is challenging, which leads to wear and/or sealing problems and consumes more time and effort. Changing or washing the filter cloths is also complicated in such structures. There may be also problems with filter cake removal, which is often facilitated by shaking the filter cloths, which however may result in further wear or damage to the filter cloth as the filling shoe will cause stress to the aperture location of the filter cloth, and the filling shoe may also be released or mispositioned in such process.

These issues have been tried to solve previously by using hinged or flexible filling shoes, which are mounted in the filter element. However also these designs have issues such as cake build-up and sealing issues, which further lead to problems such as damages to the parts or filter elements. Also the cake build-up is difficult to monitor in such structures. These issues have an impact to the whole process requiring further monitoring and maintenance work.

Therefore the is a need to find better solutions to provide the material to be filtered into the horizontal pressure filter with vertical filter elements. There is also a need to provide better pressure filter apparatuses, such as more compact, more reliable, simpler and/or easier to clean and to maintain, as well as related filling shoes.

Summary

In the present invention it was found out how to overcome problems of prior art. In the present apparatus and method a specific floating filling shoe is provided, which is not inserted in the filter cloth.

The present disclosure provides a filling shoe 30 for providing suspension of solids into a pressure filter apparatus, preferably together with two or more compatible vertical filter plates 10a, 10b, the pressure filter apparatus comprising

-two or more vertical filter elements 16a, 16b each comprising a vertical filter plate 10a, 10b having a first recess 14 and a filter cloth 12a, 12b covering the first recess, wherein two adjacent vertical filter elements 16a, 16b are arranged to form a filter chamber between opposing first filter cloth 12a and second filter 12b cloth between a first filter plate 10a and a second filter plate 10b for obtaining a filter cake from a suspension of solids in the filter chamber when the suspension is filtered through the filter cloths, wherein at least one of the vertical filter elements 16a, 16b is movable in horizontal direction for closing and opening the filter chamber, -the vertical filter plates 10a, 10b each comprising one or more channels 18 connected to the space between the first recess of the filter plate and the filter cloth covering the first recess for outputting a filtrate during filtration, wherein -each of the vertical filter plates 10a, 10b comprises a second recess 20 at a vertical outer side 50, 52, such as at an upper part of the vertical outer side, of the vertical filter plate, the second recesses 20 of two adjacent filter plates 10a, 10b together forming an aperture from the vertical outer sides of the two adjacent vertical filter plates to the filter chamber, which aperture is arranged to releasably receive the filling shoe 30 for inputting a suspension of solids to the filter chamber, wherein

-the filling shoe 30 comprises a body arranged to fit to the aperture formed by the second recesses 20 of the two adjacent filter plates 10a, 10b together, the body comprising an inlet 32 for receiving the suspension of solids and an outlet 34 for providing the suspension of solids to the filter chamber.

The present disclosure also provides a pressure filter apparatus comprising

-two or more vertical filter elements 16a, 16b each comprising a vertical filter plate 10a, 10b having a first recess 14 and a filter cloth 12a, 12b covering the first recess, wherein two adjacent vertical filter elements 16a, 16b are arranged to form a filter chamber between opposing first filter cloth 12a and second filter cloth 12b between a first filter plate 10a and a second filter plate 10b for obtaining a filter cake from a suspension of solids in the filter chamber when the suspension is filtered through the filter cloths, wherein at least one of the vertical filter elements 16a, 16b is movable in horizontal direction for closing and opening the filter chamber,

-the vertical filter plates 10a, 10b each comprising one or more channels 18 connected to the space between the first recess of the filter plate and the filter cloth covering the first recess for outputting a filtrate the during filtration,

-a filling shoe (30) for providing the suspension of solids to the filter chamber, wherein

-each of the vertical filter plates 10a, 10b comprises a second recess 20 at a vertical outer side 50, 52, such as at an upper part of the vertical outer side, of the vertical filter plate, the second recesses 20 of two adjacent filter plates 10a, 10b together forming an aperture from the vertical outer sides of the two adjacent vertical filter plates to the filter chamber, which aperture is arranged to releasably receive the filling shoe 30 for inputting a suspension of solids to the filter chamber, -the filling shoe 30 comprising a body arranged to fit to the aperture formed by the second recesses 20 of the two adjacent filter plates 10a, 10b together, the body comprising an inlet 32 for receiving the suspension of solids and an outlet 34 for providing the suspension of solids to the filter chamber.

The present disclosure also provides a method for updating a pressure filter system, the method comprising

-providing a pressure filter apparatus,

-providing the one or more filling shoes and two or more compatible vertical filter plates, optionally two or more compatible filter cloths, and

-installing the one or more filling shoes and two or more compatible vertical filter plates, optionally the two or more compatible filter cloths, to the pressure filter apparatus.

The present disclosure also provides a method for operating a pressure filter apparatus, the method comprising

-providing the pressure filter apparatus,

-providing closed filter chamber(s), if necessary by moving the movable vertical filter elements 16a, 16b to close the filter chamber(s) and to seal the filling shoes 30 to the vertical filter plates 10a, 10b,

-providing a suspension of solids to the filter chamber through the filling shoe(s), -filtering the suspension through the filter clothes 12a, 12b to obtain a filtrate and to obtain filter cake(s) in the filter chamber(s),

-after filtration moving the movable vertical filter elements 16a, 16b to open the filter chamber(s) to discharge the filter cake(s), preferably to release the filling shoes and/or to maintain the position of the filling shoes at the level of the second recesses 20 in the vertical filter plates 10a, 10b.

The main embodiments are characterized in the independent claims. Various embodiments are disclosed in the dependent claims. The features of the embodiments and the examples disclosed herein are mutually freely combinable unless otherwise explicitly stated.

The present filling shoe and arrangement provides several advantages. First of all, no holes or apertures in the filter cloth are required as no filling shoes are installed in the filter cloth. Therefore the filter cloth can be continuous, which simplifies providing, installing, using, cleaning and changing the filter cloth. The continuous filter cloths with no apertures are easy to manufacture and less expensive compared to specific filter cloths with a dedicated aperture for a filter shoe used, which may vary in different filter setups. Changing the filter cloth is easy and fast as the filter shoe is not attached to the filter cloth, and the changing can be carried out without disassembling the filter structure. The cloth position is not critical. It is also possible to use different thicknesses of filter cloths, as the filter cloth does not affect the function of the filling shoe.

In the present setup all parts can be washed or cleaned easily, and all gaps are opened automatically. The structure also enables easy and reliable sealing of the filling shoe. Different materials can be used in the filling shoe, such as full rubber, plastic or other elastic material design, which provides self-sealing functions against pressure. O-rings and the like sealing parts can be provided, but it is also possible to provide filling shoe structures without separate sealing parts. The setup is simple as there are only few components.

The filling shoe can be controllably released from the filter elements when the filter stack is opened. The filling shoe can be provided as self-positioning, wherein the filling shoe will set back to the correct position when the filter stack is closed, so the guiding accuracy is not critical. Filling shoes can run on the same beam as the filter plates. Double or more top side feed is possible, but it is also possible to provide a feed only on one side, for example in small filter apparatuses.

During the use the present arrangement provides reliable filter cake release, as the filter cloths can be smooth without holes or filling shoes. The cake can be released by shaking the filter cloth, and as there is no filling shoe attached to the filter cloth the shaking does not damage the filter cloth or release the filling shoe. A new plate pack design is possible, which can be provided as an upgrade to existing side bar filters or other filter types.

Brief description of the figures

Figure 1 shows an example of a pack of vertical filter elements in a horizontal pressure filter apparatus. Figure 1a shows the pack as opened and Figure 1 b show the pack as closed.

Figure 2 shows an example of a filling shoe. Figures 2a and 2b show views from different angles, and Figure 2c shows a cross section view of the filter shoe.

Figure 3 shows an example of the attachment of the filling shoes in an arrangement. Figure 3a shows how the filling shoes are attached to filter plates via guiding parts, which allow movement of the filter elements while maintaining the positions of the filling shoes at the correct level. Figure 3b show a cross section of another example, wherein the suspension channels formed in the filter pack can be seen.

Detailed description

In this specification, percentage values, unless specifically indicated otherwise, are based on weight (w/w, by weight, or wt%). If any numerical ranges are provided, the ranges include also the upper and lower values. The open term “comprise” also includes a closed term “consisting of’ as one option.

The pressure filter apparatus, or a system comprising the pressure filter apparatus, further comprising the filling shoe is described herein. The description applies to the filling shoe designed to fit to the pressure filter apparatus as well as to the pressure filter apparatus comprising the filling shoe. The parts of the pressure filter apparatuses are described as installed, for example as shown in the figures, so the terms such as “side”, “outer”, “upper” and “lower” refer to the directions in the apparatus when provided as ready for use. In general the upper ends of the parts in the installed position, such as plates, recesses, and other associated parts, may be called first ends, and the lower ends may be called second ends.

The filter apparatus discussed herein may be used for filtering, dewatering and/or drying any suitable particulate solid matter, which may comprise inorganic and/or organic matter. Examples of inorganic solids and/or particulates include materials from mineral and mining industry, for example concentrates of iron, chromium, copper, zinc, nickel, gold or phosphates, or tailings of iron, copper, molybdenum, phosphorus or quartz sand. The filter apparatuses may be used for filtering cellulosic materials and the like organic materials as well. The particulate and/or solid matter or material as discussed herein refers to any applicable suspension, dispersion and/or slurry of (solid) particles, which can be filtered to remove liquid and to separate the solids, preferably as a dewatered filter cake, and to dewater and dry the suspension, dispersion and/or slurry. The filtered material can be easily discharged from the apparatus, recovered and used for desired purposes.

The filter apparatus discussed herein is a horizontal pressure filter apparatus, but the same principle can be applied to vertical pressure filter apparatuses as well, wherein the filter element or filter plates are horizontal, and which may filter in two directions. In such case differing features, such as mounting or suspension of filter plates, as well as channels, tubing, actuators etc., may be modified to apply to the vertical filter apparatus. For example vertical mounting or suspension of horizontal plates may be provided, such as to vertical support elements.

The present pressure filter apparatus comprises

-two or more vertical filter elements 16a, 16b each comprising a vertical filter plate 10a, 10b having a first recess 14 and a filter cloth 12a, 12b covering the first recess, wherein adjacent two vertical filter elements 16a, 16b are arranged to form a filter chamber between opposing first filter cloth 12a and second filter cloth 12b between a first filter plate 10a and a second filter plate 10b for obtaining a filter cake from a suspension of solids in the filter chamber when the suspension is filtered through the filter cloths, wherein at least one of the vertical filter elements 16a, 16b is movable in horizontal direction for closing and opening the filter chamber.

The filter plates may be made of light material, such as plastic and/or plastic composite material, for example thermoplastic polymers, such as polyethylene or polypropylene. The filter plates may have a largest height and/or a largest width in the range of 100-500 cm, such as 100-300 cm, for example, and a largest thickness in the range of 5-15 cm. However the system is scalable to other dimensions as well.

The vertical filter plates have a first end 54, which is the upper end when the vertical filter plates are installed in the apparatus, and a second end 56, which is opposite to the first end and which is the lower end when the vertical filter plates are installed in the apparatus. The vertical outer sides, such as vertical (outer) edge sides, of the vertical filter plates, i.e. a first outer side 50 and a second outer side 52, refer to the vertical outer sides of a filter stack when the vertical filter plates are installed in the apparatus, as shown in the figures. The largest sides of each filter plate, i.e. sides with the largest area, which comprise the first recesses, may be called faces, such as a first face and a second face of the filter plate. In one example the first end 54 corresponds to a first side, the second end 56 corresponds to a second side, the first (vertical) outer side 50 corresponds to a third side, the second (vertical) outer side 52 corresponds to a fourth side, the first face corresponds to a fifth side and the second face corresponds to a sixth side, of a filter plate. Figures 1a and 3a show a plurality of vertical filter elements 16a, 16b, etc, which comprise a vertical filter plate 10a, 10b, 10c etc, and a filter cloth, which may be also called a filter fabric, at both faces of most filter plates. One recess 14 of a vertical filter plate is shown in Figure 1a and 1 b, and each vertical filter plate usually contains a similar recess on both face sides. The filter plate has therefore a thicker framing part at the outer sides or borders of the plate surrounding the recess part, which is at the middle of the plate and thus thinner than the framing part. The filter plates of the figures may be symmetric, so both the first outer or edge sides and/or face sides and the second and/or face sides may have identical recesses, protruding parts and channels etc, only as mirror images. It is also possible to provide asymmetric filer plates, wherein these parts are present only at one side.

In one embodiment one or more, such as two or more, of the vertical filter elements 16a, 16b, etc. each comprise a vertical filter plate 10a, 10b having a first recess 14 at both face sides of the filter plate and a filter cloth 12a, 12b covering the first recesses 14 at both face sides of the filter plate.

When two adjacent filter plates with a filter cloth covering the opposing recesses in both plates are brought together, i.e. the filter stack is closed, the opposing recesses form a filter chamber between the opposing filter cloths. The suspension of solids is conveyed to the filter chamber(s). When pressurized suspension of solids is provided to the filter chamber, and filtered through the filter cloths, a filtrate is formed between the first recess 14 and a corresponding filter cloth 12a, 12b, 12c, 12d, 12e, 12f etc. covering the recess, as water or other liquid contained in the suspension is filtered through the filter cloths and is conveyed from the filter via channel(s) formed by the channels 18 when the filter stack is closed. A filtrate is obtained, and a filter cake is formed in each of the filter chambers. The one or more channels 18 may be also connected to a container or outlet for receiving and/or collecting filtrate.

The apparatus may comprise and/or it may be connected or be connectable to a source of suspension of solids, preferably pressurized source of suspension of solids. The source of suspension of solids may comprise means for providing the suspension to the apparatus, such as pumping means, for example one or more pumps, a source of pressure and/or suspension, and/or other mechanical actuator for moving the suspension, such as one or more screws, rotating blades and/or the like means, which may be electronically controllable and operatively connected to the controlling means. The means for providing suspension may comprise an inlet for a source of suspension, such as for an outlet of a container of the suspension or other suspension system, which may be connected to the apparatus, such as to an inlet in the apparatus, preferably equipped with a valve operatively connected to the controlling means.

In most cases the source of suspension of solids comprises a pump, such as centrifugal pump. At the beginning of the process the pressure in the filter chamber is substantially 0 bar. When solids are accumulated in the filter chamber during filtering, the forming filter cake causes flow resistance and the pressure will rise, such as up to 5 bar, or higher. The duration of the pumping phase depends on the process, such as the source material, the used apparatus, filter cloths etc., but in general the duration may be in the range of 1-5 minutes, 1-60 minutes, 1-6 hours, even days in conventional implementations. The pumping may be stopped when the accumulation of solids slows down, for example when a predetermined decreased flow and/or hour capacity is achieved. This may be detected by using one or more suitable sensors operatively connected to controlling means.

The suspension may be aqueous suspension or other applicable suspension. When aqueous suspension is provided, the filtrate is aqueous solution. Other suitable liquids in addition to water-based liquids may be applicable, such as organic solvents.

The vertical filter plates 10a, 10b, 10c etc. each comprise one or more channels 18 connected to the space between the first recess 14 of the filter plate and the filter cloth 12a, 12b, 12c, 12d, 12e, 12f etc covering the first recess for outputting a filtrate the during filtration. More particularly the vertical filter plates comprise apertures connected to and/or forming a part of a filtrate channel, to obtain and/or output the forming filtrate during filtering. The space between the first recess of the filter plate and the filter cloth covering the first recess may be enabled and/or facilitated by providing a plurality of protrusions and/or cavities in the first recess 14, more particularly on the surface of the filter plate in the area of the first recess. The protrusions and/or cavities may be nodular, or they may comprise other shapes or forms, which facilitate maintaining gas and/or liquid communication between the first recess of the filter plate and the filter cloth covering the first recess. Without the protrusions and/or cavities the filter cloth could be pressed tightly against a flat surface of the first recess when the pressure is applied, which could prevent even distribution of filtrate to the whole area of the filter cloth covering the first recess, i.e. at the filter chamber. The pressures utilized in the process may comprise positive and/or reduced pressure, which may be also called negative pressure or vacuum.

The filter apparatus may comprise or may be connected, more particularly the filter plates may be connected, to a source of positive and/or negative pressure, such as reduced pressure, such as vacuum pump or other source of reduced pressure. The source of pressure may be connected to the one or more channels 18 in the filter plates by hoses, tubes or other suitable connecting structures. The source of pressure may be an electric device, such as a pump, and/or it may comprise one or more electrically controllable actuators, such as valves or the like, which can be operatively connected to controlling means, and can therefore be controlled by the controlling means.

The vertical filter plates 10a, 10b, 10c etc. each may comprise one or more further apertures and/or channels, and/or apertures forming channels when the filter stack is closed, such as for drying air, for pressurized air and/or for liquid, such for water, which may be used for washing and cleaning the apparatus or parts thereof.

A filter plate may also comprise an elastic diaphragm between the filter plate and the filter cloth, such as at the first recess, wherein the space between the filter plate and the diaphragm is connected or connectable to a source of pressurized air and/or liquid, such as water, preferably via a channel for air and/or via a channel for liquid. After the filtering, such as wherein providing the suspension is stopped or ceased, pressured air or pressured liquids may be provided to the space between the filter plate and the diaphragm to cause pressure to the filter cake to remove liquid. Also pressurized air may be provided through the filter cake to remove liquid. After a desired moisture content or degree of dewatering is obtained, the filter cake may be removed by opening the filter chamber.

The one or more channels 18 or apertures for forming the channels 18 connected to the space between the first recess of the filter plate and the filter cloth covering the first recess are usually at the lower end of the vertical filter plates. In the examples presented in the figures the channels 18, or the apertures connected to the channels, are at the outer sides 50, 52 of the filter plates in protruding parts, but the channels 18 may be also located at other sites at the lower end 56 of the filter plates outside the area of the first recess 14. However if the channels 18 would be below the area covered by the filter cloth, this would require providing a filter cloth with such length that the filter cloth would not cover the channels 18. When the channels 18 are at the sides or the frames, which are outside the width and/or the length of the filter cloth, the length of the filter cloth is not critical and it is possible to provide a weight bar 13 or other additional part at the second end of the filter cloth.

In one embodiment the one or more channels 18 for outputting a filtrate during filtration are arranged at the lower part or the second end of the vertical filter plates 10a, 10b, outside the area covered by the filter cloth 12a, 12b to form a filtrate channel through the two or more vertical filter plates when the filter plates are moved together to close the filter chambers. The one or more channels 18 for outputting a filtrate during filtration may be at the level of the lower part or the second end of the filter chambers and/or first recesses 14, or even below.

Each of the vertical filter plates 10a, 10b may comprise a second recess 20 at an upper part of a vertical outer side of the vertical filter plate, such as at the first vertical outer side 50 and/or at the second vertical outer side 52, the second recesses 20 of two adjacent filter plates 10a, 10b together forming an aperture from the upper part of the vertical outer side to the filter chamber, which aperture is arranged to releasably receive the filling shoe 30 for inputting a suspension of solids to the filter chamber. The filling shoe is received in such way that it can be released from the filter plates when the filter plates are moved, i.e. by the effect of opening the filter stack, and the filling shoe can similarly be received back to the aperture when the filter stack is closed. Therefore the filling shoe is released completely from the filter plates, and is only suspended by connecting elements 46. The filling shoe is not attached to the filter plates at the second recess, i.e. the second recess does not contain attaching parts for the filling shoe, such as a hinge or the like.

The second recesses may be at or close to the first ends 54 of the vertical filter plates, usually at a level which is at the level of the upper end (first end) of the first recess or the filter chamber, for example above the horizontal centre line of the first recess/the filter chamber, to allow forming a horizontal or substantially horizontal channel directly to the filter chamber. It is desired to fill the filter chamber from its upper end to allow efficient flow of suspension by gravity. The filling shoe aperture formed by the second recesses 20 of two adjacent filter plates 10a, 10b together is designed to closely fit to the filling shoe. It is desired to obtain a tight and/or sealed fitting of the filling shoe to the aperture.

The filling shoe 30 comprises a body arranged to fit to the aperture, preferably a body arranged to releasably fit to the aperture, formed by the second recesses 20 of two adjacent filter plates 10a, 10b together, the body comprising an inlet 32 for receiving the suspension of solids and an outlet 34 for providing the suspension of solids to the filter chamber.

The filling shoe comprises a body, which may have one or more parts. In the examples of Figures 2a-2c the body has a bevelled insert part 38 and a rectangleshaped base part 40. The filling shoe has a first end, which is the end inserted into the filling shoe aperture in the filter stack and/or the end comprising the outlet 34, which is in communication with the filter chamber when inserted, and a second end, which is the end that points outside from the filter stack and/or the end comprising the inlet 32. The first end and the second end define the length of the filling shoe. The body has a height between the upper and lower end of the filling shoe when installed, and a thickness, which is the thickness of the body between two adjacent filter plates and the shortest dimension of the filling shoe as can be seen in Figures 2a and 2b.

In Figures 2a-2b the insert part 38 is at the first end, and the base part 40 is at the second end. The insert part 38 is arranged to fit closely to the aperture formed by the second recesses 20 of two adjacent filter plates 10a, 10b together. The aperture and/or the filling shoe, such as the insert part and/or the base part, may comprise one or more sealings, such as elastic sealings. For example the insert part may have a groove for receiving a rubber seal ring, which facilitates sealing the insert part with filter cloths. The filling shoe may be made from elastic material and therefore can seal the structure, and in such case there may not be a need to include other sealing means. The elastic material refers to material exhibiting such elasticity that can be utilized for sealing the filling shoe during closing of the filter stack during regular use of the filter apparatus, such as rubber, silicone, or other suitable elastic materials. Other materials may be also included in the structure of the filling shoe, for example metallic reinforcing parts may be included, or the like. In one embodiment the body of the filling shoe 30 comprises metal, plastic, rubber, silicone, or composite material or combination thereof. The filling shoe may be made of or comprise thermoplastic polymer, such as polypropylene or polyethylene. The (largest) thickness of the filling shoe, or an insert part of the filling shoe, in the horizontal direction, i.e. between the filter plates may be in the range of 30-100 mm, such as 30-50 mm, for example about 40 mm. The depth of a second recess in each filter plate therefore substantially corresponds to half of this thickness, and any compressibility of the shoe material and/or included sealing material may have impact to the exact dimensions.

The filling shoe, or the body thereof, comprises an inlet 32 for receiving the suspension of solids and an outlet 34 for providing the suspension of solids to the filter chamber. The filling shoe may comprise an aperture 32 which allows the suspension of solids to enter the filling shoe, and which aperture can act as the inlet or be a part of the inlet. In the examples of figures 2a-2c the aperture 32 is in the base part 40 of the body of the filling shoe 30, and the apertures 32 of filling shoes, when the filter stack is closed, form a suspension channel 25, which is perpendicular to the channels 36 leading to the filter chamber. The aperture 32 may have a diameter in the range of 50-200 mm, such as 100-200 mm, for example about 150 mm. The outlet channels 34 have a smaller diameter and are limited by the thickness of the filling shoe and the insert thereof. The suspension channel 25 may be formed by the apertures 32 in the filling shoes 30 together with the apertures 24 in the filter plates 10a, 10b, 10c etc. The body of the filling shoe may comprise one or more apertures 42 or other connecting points for attaching the filling shoe to a connecting element, i.e. to maintain the position of the filling shoe during the use of the filter apparatus. The filling shoe may comprise means for attaching the filling shoe to a support only at the second end, such as one or more attaching parts and/or apertures for such parts or means. The apertures 42 shown in Figures 2a and 2c may receive a peg, a bolt or the like attaching part. The filling shoe preferably does not contain any means for attaching the filling shoe at the sides of the filling shoe facing the filter plates. This facilitates providing the filter cloths between the filter plate and the sides of the filling shoe, and release of each filter cloth as well a complete release of the filling shoe from the filter plates when the filter stack is opened.

When the suspension channel 25 is formed through adjacent filling shoes by the inlets 32, the feed can be arranged from a side, such as from one side only, and preferably by one tube only, of the apparatus, which enables providing apparatuses with more compact size, and/or simpler apparatuses. For example no separate tubing arrangement are required for each filling shoe separately, such as a plurality of feed tubes. This enables making the device more simple, smaller and more reliable. As there is no feed orifice at the outer end of the filling shoe, and therefore no feed tubes, this enables attaching the filling shoe at this end, for example to a connecting element 46, which enables solutions such as disclosed in Figures 1 and 3.

The shape of the filling shoe can be designed to allow correct setting of the filling shoe to the formed aperture between the two adjacent filter plates, preferably to seal the filling shoe to the aperture. For example as shown in the figures, the filling shoe, or an insert part 38 of the filling shoe, may comprise a bevelled shape, or similar functional shape, such as arched shape, which is designed to fit to the aperture formed by the second recesses 20 of two adjacent filter plates 10a, 10b and which causes the filling shoe to set correctly to the corresponding aperture between two adjacent filter plates, when the stack is closed i.e. by the effect of the movement of the vertical filter elements. Minor displacement of a filling shoe during and/or after opening of the stack has therefore no adverse effect, but when the stack is closed, the filling shoes will be correctly settled and tightly sealed to the structure, and there is no risk of misplacement of the plurality of filling shoes. There is no need to separately position the filling shoes, but the shape of the filling shoe will force the filling shoes into correct positions when the filter stack is closed.

The filling shoe is releasable and/or separate from the filter elements or from the filter plates, which means that the filling shoe will be detached from the filter elements or filter plates when the filter stack is opened, i.e. by the effect of moving the filter elements/plates. Also the filter cloth is released simultaneously. When the filter stack is again closed, the filling shoe, as well as the filter cloth, will be automatically set into correct position. Therefore the filling shoe is preferably not hinged to the filter plates or attached with protruding parts such as pins, at the opposing sides of the filling shoe and the filter plate, i.e. between the filter plates.

In one example of the filling shoe 30 as shown in Figure 3a, the filling shoe is continuous having the insert shape along the whole length of the filling shoe, and there is no separate base part. Such filling shoe can be implemented as in compact size, and it can be attached to existing connecting elements. It can also be set between the protruding parts 22 at the edge sides of the filter plates as shown in the figure 3a.

In one embodiment both the body of the filling shoe 30 and the aperture formed by the second recesses 20 of two adjacent filter plates 10a, 10b together comprise a curved and/or bevelled shape 38, preferably for facilitating the positioning and/or setting of the filling shoe 30 to the aperture during closing of the filter chamber by the effect of the movement of the filter elements. The thickness of the body or the insert of the filling shoe may be lower at the upper end and at the lower end of the body or the insert. The shape of the body of the filling shoe and the shape of the aperture are therefore compatible.

As shown in Figure 3b, when the filter stack is closed, the filter cloths 12a, 12b, 12c, 12d, 12f etc. are pressed between the filter plates and the filling shoes. The channels 36 of the filling shoes can be seen leading from the suspension channel 25 to the filter chamber between two adjacent filter cloths 12a and 12b, 12c and 12d, 12e and 12f.

Usually a pressure filter apparatus comprises a plurality of the filter elements, such as 10 or more, 20 or more or 50 or more, up to hundreds of filter elements, for example 10-200 or 50-100. The present system is well scalable in number and sizes of the filter elements or plates, as well as the size of the apparatus. In general the pressure filter apparatuses are large industrial devices, so the requirements of throughput, serviceability, reliability and scalability are high.

The filter elements are usually suspended at one or more horizontal support element(s), which may be elongated, such as a rail, such as a check rail, a bar, a beam, a rod or the like. The horizontal support elements are usually attached to a frame or a body of the filter apparatus. The filter pack, i.e. the filter elements, are movable in a horizontal direction, more particularly in the direction of the axis of the support element(s), so that the filter pack can be opened and closed when necessary.

The apparatus usually comprises a stationary element at a first end of a set or a stack of two or more vertical filter elements and a moving (movable) element at a second end of the set or a stack of two or more vertical filter elements, wherein movement of the moving element is arranged to move the movable vertical filter elements to open or close the filter chambers. The moving element may be attached to an actuator for moving the moving element, such as an electric motor or pneumatic actuator, which is controllable by controlling means, such as a control unit, so the moving element may be operably connected to controlling means. When the moving element is moved, the moving element will drag the filter elements of the stack, as the filter elements, or the filter plates, are usually attached to each other by connecting parts, which may allow opening the stack in required amount.

In one embodiment the vertical filter elements 16a, 16b are supported by and movable along and/or on one or more elongated horizontal support elements at the outer sides of the vertical filter elements. The vertical filter elements, or the vertical filter plates, may comprise a projection or other protruding or connecting part, which is arranged to contact the horizontal support elements to support the filter plates, such as comprising sliding means or part for free movement along the horizontal support element. The projection or other protruding or connecting part may be an integral part of the filter elements, such as shown in figures. A stack of filter elements/plates may be supported by two horizontal support elements at two vertical sides of the vertical filter elements, and correspondingly the filter elements may comprise two projections or other protruding or connecting parts on two vertical sides of the filter elements, so that the filter elements will be supported by two sides. The two opposite vertical sides of the filter elements or the filter plates may be identical but mirrored, i.e. both sides may comprise similar projections, filling shoes, apertures for the filling shoes and/or the related connecting parts and other parts. It may also be possible that the filter elements are supported from the top side, but this may limit the types of usable filter cloths.

In one embodiment each of the vertical filter plates comprise a horizontal projection 22 at an upper part of a vertical outer side 50, 52 of the vertical filter plate 10a, 10b at the location of the second recess 20 for receiving a filling shoe 30, the horizontal projections 22 comprising an aperture 24 arranged to be in communication with the inlet of the filling shoe 30 and to form a suspension channel 25 in the two or more adjacent vertical filter plates 10a, 10b, preferably together with the inlet 32 of the filling shoe, when the filter plates are moved together to close the filter chambers. As shown in Figures 1a, 1 b and 3a, the projections 22 set on the elongated horizontal support element 26, and are movable along the support elements. The horizontal projection 22 may be at the level of the upper part of the filter chamber, which allows providing the filling shoe at the level of the upper part of the filling shoe. Preferably the filling shoe, or the inlet channel of the filling shoe, is provided at the top of the filter chamber to allow complete filling of the filter chamber with the suspension.

The filter cloth, or the filter fabric, is a cloth or fabric made of material tolerating the conditions of the pressure filter apparatus, such as pressure, mechanical stress and the like and which has a suitable porosity for filtering the suspension of solids or other material in question. Therefore the filter cloth may be selected according to the filtered material, and by changing the filter cloths it is possible to filter different materials with the same apparatus. The filter cloth may comprise or be made of plastic polymer(s), such as polypropylene, polyester, polyamide, polyvinylidene fluoride (PVDF), polyphenylene sulphide (PPS) or the like. The filter cloth may be woven, and it can also be a felt cloth. The permeability of the filter cloth may be defined by features such as yarn type, yarn thickness, yarn density, type of weave, heat treatment and other post-processing treatment and the like. The filter cloth may have a single or double layers, and it may have hook and/or loop fasteners, sealing and/or reinforcement on edges and optionally at location of channels, which may be close to edges.

The filter cloth may be rectangular and it may be simply suspended from a first end to a vertical filter plate, such as to the upper or top side 54 of the filter plate, which is the first end of the filter plate. Each filter plate has separate filter cloth(s), usually two separate filter cloths, one on each face side of the filter plate. The filter cloth may be attached from the first end to a bar, for example by hook and/or loop fasteners, which bar may be attached to the filter plate or above it, or the filter plate or a part above it may comprise other types of attaching means for attaching the filter cloth and to allow the filter cloth to set onto the correct position by the effect of gravity. The filter cloth may have a weight element 13 at the second end of the filter cloth, which is opposite to the first end of the filter cloth, and which is the lower end when the filter cloth is installed in the filter element, such as a bar attached to the second end of the filter cloth, as shown in Figure 1a. In one embodiment the filter cloth 12a, 12b is suspended at the upper part of the corresponding filter plate 10a, 10b.

In one embodiment each filter cloth 12a, 12b is continuous. The term “continuous” refers to a filter cloth or fabric, wherein the whole or at least the part of the cloth or fabric, which covers or is intended to cover the first recess 14 of the corresponding vertical filter element 10a, 10b etc, is continuous, i.e. is free of apertures or does not contain an aperture. The apertures refer to apertures of substantial sizes, such as apertures for feedthrough, such as for filling shoes of conventional types, and in general apertures larger than for example 1 mm, 5 mm or 10 mm. The “aperture” does not refer to the filtering pores of the filter cloth. A continuous filter cloth may include further parts at the ends of the filter cloth, such as the bars or other weight elements and the like, or other parts such as channels which are not at the location of the first recess 14, i.e. not at the location of filter chamber or at the area of the vertical filter elements, at the location of the second recess 20, and/or which could interfere the formation of functional and/or tight filter structure.

In the example shown in Figures 1a and 1 b (the stationary and moving elements at the ends of the filter element sets or filter stacks are not shown), the filter stack is opened (Figure 1a) to such degree that a filter cake formed between two adjacent filter elements can be discharged. The filter elements are usually horizontally moved few centimetres apart from each other, such as 2-10 cm, so that the filter cake can be released. At this point it is possible to easily remove and/or insert a filter cloth from and/or to the apparatus, if necessary for cleaning, service and/or replacing purposes. The filling shoes do not limit these operations in any way, but the filling shoes can be released as the stack opens. The movement may be limited by connecting elements 46 between the filter element or filter plates, so the connecting element may be arranged to define the maximum distance between the filter elements or filter plates when the filter stack is opened. The connecting part 46 may comprise loops or the like structures enabling the limited movement of the filter elements defined by pins loosely fitted to elongated apertures of the connecting part, when the stack is opened, as shown in figures 3a and 3b. As the present system does not require changing filling shoes attached to the filter cloths or carrying out any cleaning operations of such parts, which would require disassembling the filter element stack, it is not necessary to regularly open the filter stack more than the few centimetres. The connecting elements may remain at their positions. The present system enables providing such attachment of the filling shoes that maintains the level of the filling shoes in the setup when the stack is opened, such as the attachment structure shown in Figure 3a.

In one embodiment the filling shoe 30 comprises or is attached to a connecting element 46 arranged to maintain the position of the filling shoe during moving the filter elements. The position may refer to vertical position, i.e. to vertical level. The connecting element may be arranged to connect the filter plates and limit the horizontal movement of the filter plates, i.e. to define the maximum distance between the filter elements or filter plates when the filter stack is opened.

The filling shoe 30 and/or the connecting element 46 may be supported by and/or attached to one or two vertical filter plate(s) 10a, 10b. The filling shoe may be attached or fixed to a connecting element 46 by attaching means, such as bolts 44, and the connecting element 46 can be movably suspended by attaching means, such as bolts 45, pins of the like parts, attached to the filter elements 10a, 10b, 10c, and loosely fitted to elongated apertures in the connecting element. The connecting elements 46 can be attached to the second end of the filling shoe, which is the outer end of the filling shoe when installed, so no attaching parts are present between the filling shoe and the filter plate or filter element. The elongated apertures in the connecting parts 46 allow limited horizontal movement of the required few centimetres of the filter elements/plates, while maintaining the level of the filling shoes 30, more particularly the connecting parts of the vertical apertures therein may prevent vertical movement of the filling shoe, so that when the stack is again closed, the filling shoes 30 will set into correct positions in the apertures formed between two adjacent filter plates. The connecting elements may be designed to tolerate the mechanical forces required for opening the filter stack, and they can also carry and move the filling shoe. The filling shoe may be integrated with the connecting elements. The filling shoe can be also supported by other part.

The connecting element 46 may be attached at the outer sides 50, 52 of the filter elements, and preferably not between the filter elements. When the filling shoes are attached to one or more filter plates, preferably by using the existing connecting elements in the filter stack, it is possible to provide a more compact and/or different shape, size and/or form of filling shoe compared to a situation, wherein the filling shoe is attached to the horizontal support element, or to other supporting part in the apparatus.

In one embodiment the filling shoes 30 are supported by the one or more elongated horizontal support elements 26 at the outer sides 50, 52 of the vertical filter plates and/or by the vertical filter plates 10a, 10b etc. The filling shoes may be attached to or supported by a connecting element 46, preferably via a peg, a bolt, or any other applicable element loosely fitted to elongated apertures in the connecting element, which may connect the filling shoe to support element(s) 26.

The connecting element may be a guiding part 46, which is arranged to maintain the position and/or the level of the filling shoe during moving the filter elements, and preferably to guide the filling shoe to a correct position. The connecting element may be attached or suspended to the elongated horizontal support element 26 or to one or two filter plate(s) 10a, 10b from the outer end of the filling shoe, which is the second end of the filling shoe. When the filling shoe is attached to a support from its outer end rather than from the sides, it can be removed from the system when the filter stack is opened the few centimetres required to discharge the filter cakes. It is not necessary to dismantle the filter stack for such operations. Such structure also allows access between the filling shoe and the filter plate. Therefore it is desired that there are no links or attaching or guiding parts (directly) between the filling shoes and the filter plates, especially at opposing sides of these parts. The filling shoe is preferably released from the filter plates when the stack is opened.

The connecting element 46 may suspended to the elongated horizontal support element 26, such as to a rail. In such case the filling shoe is arranged to maintain its position at a desired level, which is defined by the level of the connecting element, and the filling shoe can slide on the support element when the filter plates are moved.

In one example the filling shoe(s) comprise(s) a connecting element, such as a guiding part, 46 comprising two or more elongated horizontal apertures arranged to be supported by two or more compatible projections 45 or other attaching parts at the sides of two adjacent filter plates, the connecting elements being arranged to maintain the position of the filling shoe during moving the filter elements. The connecting element may be a plate or it may have other applicable form. The compatible projections 45 at the sides of two adjacent filter plates may be pegs or bolts or other suitable protruding parts, such as shown in Figure 3a. In this example the filling shoes 30 are attached to the filter plates 10a, 10b, 10c via connecting elements 46, so the filling shoes are not supported by the supporting element 26. This allows using different support element structure and/or location, and also different structure of the filling shoe, for example which does not require a specific base part 40 which would support the filling shoe.

The apparatus may comprise a vibrating or shaking means, such as one or more electrical shakers, vibrators or other actuators providing pulsed movement, such as shaking or vibrating movement. The vibrating or shaking means may be connected to a filter cloth, and preferably operatively connected to the controlling means. With the vibrating or shaking means it is possible to release any remaining filter cake material from the filter cloth and/or the filter plate between the filtering runs. Powerful vibration or shaking can be applied as the filter cloths does not contain any such parts, such as filling shoes, in the middle of the cloth, which could be released by the movement or which could damage the filter cloth. The apparatus may comprise a supply of liquid, such as water, which can be used for washing the apparatus or parts thereof when necessary. With the present solution the washing is not necessary as often as with conventional structures but must be carried out when necessary. The liquid may be provided via one or more channels in the filter plates and/or externally, such as by spraying.

The present disclosure also provides a vertical filter plate disclosed herein, preferably two or more or a plurality of filter plates compatible with a filter apparatus and filling shoes. Such separate filter plates may be provided to update an existing pressure filter apparatus. The vertical filter plates may be provided with the compatible filling shoes, and/or with compatible filter cloths. Compatible refers to such design that the compatible parts are designed and/or adapted to fit to each other and to a filter apparatus, such as to obtain the filter stacks discussed herein in a working and sealable form.

One embodiment provides one or more filling shoes and two or more compatible vertical filter plates, optionally two or more compatible filter cloths. This combination may be called as a set and/or a filter stack. Such a combination may be provided as a replacement filter stack for updating an existing pressure filter apparatus. The filter plates and associated parts may be designed to fit to an existing apparatus, for example to be suspended to existing horizontal suspending elements and to be attached to existing stationary and moving elements. Any parts for providing the suspension of solids may be provided as adapted to the updated filter stack and filling shoes, such as tubing and any associated parts to connect to the suspension channel(s).

The present disclosure also provides a method for updating a pressure filter system, the method comprising -providing a pressure filter apparatus,

-providing the one or more filling shoes and two or more compatible vertical filter plates, optionally two or more compatible filter cloths, i.e. a filter stack or a replacement filter stack, and

-installing the one or more filling shoes and two or more compatible vertical filter plates, optionally the two or more compatible filter cloths, to the pressure filter apparatus, such as by replacing the existing filter shoes, vertical filter plates and optionally filter cloths. The method may comprise removing the original filling shoes, filter plates and/or filter cloths before installing the new parts. The present disclosure provides a method for operating a pressure filter apparatus, the method comprising

-providing the pressure filter apparatus disclosed herein,

-providing closed filter chambers, optionally, if necessary, by moving the movable vertical filter elements 16a, 16b to close the filter chambers and to seal the filling shoe(s) 30 to the vertical filter plates 10a, 10b, and

-providing a suspension of solids to the filter chamber through the filling shoe(s). Preferably the suspension of solids is provided as pressurized.

The filter chambers are closed when the suspension of solids is conveyed to the filter chambers. The filter chambers are filled, such as filled completely or substantially completely and the filling of the filter chambers, i.e. providing the suspension of solids to the filter chambers, is continued until a decrease in capacity is obtained. This may be monitored and/or controlled by providing one or more sensors, such as a pressure sensor, a weight sensor, a suspension level sensor, a conductivity sensor or the like, or by determining the volume of the suspension during conveying into the filter chamber. This process may also be operatively controlled by the controlling means. All filter chambers may be filled simultaneously. In most cases a pressure sensor and/or a weight sensor are provided and used for detecting and/or monitoring the change in pressure and/or change in the weight of the filter.

The method comprises filtering the suspension through the filter clothes 12a, 12b to obtain filtrate and to obtain filter cakes in the filter chambers. The process may be continued until a desired dry matter content of the filter cake is obtained and/or when the formation of filtrate is ceased or begins to cease. The filtering may also be carried out for a predetermined filtering time, which has been found out to be adequate to provide the desired dry matter content. Applying pressure to the filter cake with a diaphragm may be carried out, for example as a final step. The moisture and/or dry matter content of the forming/formed filter cake may also be monitored with one or more sensors placed in the filter chamber, and/or with one or more sensors monitoring the forming/formed filtrate, such as flow rate, absorbance, conductivity and/or level of the formed filtrate, such as change of the level of the formed filtrate.

After filtration the movable vertical filter elements 16a, 16b etc are moved to open the filter chambers to discharge the filter cakes. The position of the filling shoes can be maintained at the level of the second recesses 20 in the vertical filter plates 10a, 10b, especially when the connecting elements 46 and/or other connecting means connected to the filling shoes are used. The filter cloths may be shaked at this point to remove all the filtered material. Cleaning and service procedures can be also carried out, if necessary.

The apparatus may comprise one or more electronic controlling means, such as a control unit, operatively connected to any electronically controllable means of the apparatus to allow electronic, preferably fully or partly automated, operation and control of the apparatus. “Operatively connected” refers to an arrangement wherein the controlling means can operate the controllable means, preferably in addition to monitoring the functions thereof and/or monitoring any conditions from the apparatus, for example by monitoring information provided by sensors and other information providing means.

The electronic controlling means may be operatively connected to the source of pressure and/or to the actuator for moving the moving element. The electronic control means may be also operatively connected to any other controllable parts of the system, such as disclosed herein or other parts, for example valves, actuators, pumps, switches, sensors, and/or heating and/or cooling means.

The electronic controlling means comprises one or more processors and memory, and a user interface, a display, a keyboard, a touch screen and/or other inputting means, power connection, a network connection, which may be wired and/or wireless, and/or connections to each of the controllable means of the apparatus as disclosed herein. The electronic controlling means may comprise one or more computers and/or embedded systems, such as Programmable Logic Controller (PLC). The electronic controlling means may be programmable and may comprise software, which is arranged when run with the processor, to carry out one or more controlling actions to carry out the present method and optionally one or more other methods, in general the operation of the apparatus. As the means of the apparatus, including one or more of actuators, valves, relays, motors, such as one or more of electric motors, pumps, heating means, sensors, such as temperature sensors, pressure sensors, light sensors, position sensors, weight sensors, pressure sensors, and/or flow sensors, cameras and the like parts, which may be required to monitor and carry out operations, are electronically connected to the controlling means, the controlling means can be arranged, including programmed, to operate these means. The software contained in the controlling means can be updated to provide new functionalities and/or properties. By controlling said means it is possible to obtain and/or maintain the desired operation of the apparatus or system comprising the apparatus. A desired operation may comprise for example obtaining and/or maintaining a certain (predetermined) value, such as keeping a variable at a defined range by providing controlling actions having effect to the variable, such as temperature, flow speed, rotation speed, level of liquid or suspension, level of negative and/or positive pressure, pH, concentration of an acid or other substance, and the like.

A control unit with the connected sensors, actuators, motors, pumps, relays and other applicable devices, as well as any switches, connectors, controlling devices, adapters, transformers and the like, which are required in the system, or with connections to said devices, may form a control system or the electronic controlling means or be a part of it. The control system includes required wiring between the parts thereof, and/or wireless connections. The electronic controlling means, the control system and/or the control unit may be connected and connectable to a remote system, which may have a display and a user interface, and which enables controlling and/or monitoring the operation of the system or the apparatus from remote.

Examples

An existing Roxia horizontal filter plate apparatus comprising 50 filter plates suspended at horizontal slide rails was updated with filling shoes and compatible filter plates according to the present invention. The new filter stack comprised polypropylene filter plates sized 1500 x 1500 mm and having a thickness on 100 mm, and having suspending points at the same location as in the previous filter plates. The new filter plates comprised first recesses of similar size as the original filter plates. After the old filter plates were removed, the new filter plates were installed on the slide rails and attached to each other with connecting loops 46 made of stainless steel. The filter plates were also attached to a stationary element and to a movable element of the apparatus.

Compatible releasable filling shoes made of polypropylene and having a bevelled shape with a largest thickness of 40 mm between the filter plates with 150 mm suspension channel 32 diameter were also installed between the filter plats and attached to the connecting loops, so that when the filter stack was opened, the connecting loops pulled the filter plates away from each other and defined the gaps between the filter plates, while the filling shoes fully separated from the filter plates and remained at the original level.

The original filter plates included filling shoes hinged and attached to the filter plates at the same level as the new filling shoes, and the new filter plates were implemented with apertures 24 for forming suspension channels 25 and apertures for forming filtrate channels 18 at the corresponding locations as in the original filter plates.

New polypropylene-based filter cloths were also installed having similar dimensions as the original filter cloths, as the locations of the channels 18, 25 remained unchanged. The structure of the filter cloth was selected according to the required filter properties.

During use the updated filter stack performed perfectly and there was less need for cleaning and service of the filling shoes and related parts as the filling shoes were completely released and separated from the filter plates and the filter cloths while the filter stack was opened. Substantially less filtered material was accumulated in the new filling shoe assembly compared to the original structure. When necessary, the filter shoes and inserting sites thereof could be easily rinsed with water when the filter stack was opened, and there was no need to handle or adjust the filling shoes, or to dismantle the filter stack, during or after such operations.