Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D25/00—Filters formed by clamping together several filtering elements or parts of such elements
  • B01D25/12—Filter presses, i.e. of the plate or plate and frame type
  • B01D25/164—Chamber-plate presses, i.e. the sides of the filtering elements being clamped between two successive filtering plates
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D25/00—Filters formed by clamping together several filtering elements or parts of such elements
  • B01D25/12—Filter presses, i.e. of the plate or plate and frame type
  • B01D25/21—Plate and frame presses
  • B01D25/215—Construction of the filter plates, frames
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D25/00—Filters formed by clamping together several filtering elements or parts of such elements
  • B01D25/28—Leaching or washing filter cakes in the filter handling the filter cake for purposes other than regenerating
  • B01D25/282—Leaching or washing filter cakes in the filter handling the filter cake for purposes other than regenerating for drying
  • B01D25/284—Leaching or washing filter cakes in the filter handling the filter cake for purposes other than regenerating for drying by gases or by heating
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D25/00—Filters formed by clamping together several filtering elements or parts of such elements
  • B01D25/30—Feeding devices ; Discharge devices
  • B01D25/302—Feeding devices ; Discharge devices specially adapted for chamber filter presses

Definitions

• Pressurised air filter comprising filter plates for dewatering and drying of suspensions.
• the present invention concerns a filter plate for the dewatering and drying of suspensions as specified in the introduction to claim 1.
• Filter plates are intended to be used when dewatering suspensions or slurries. Several filter plates are place next to each other, whereby a space is formed between two neighbouring plates into which a filter cloth is placed. The filter cassette that is formed by the filter plates is compressed with a strong force, after which the space is filled with slurry. The water is filtered out from the space partly through run-off and partly through the application of pressurised air to the space. The pressurised air dries the material in the space whereby a relatively dry cake is formed, having a desired moisture content between 5 - 10%. The dry cake is subsequently used for, for example, the manufacture of pellets in the manufacture of iron.
• the two neighbouring plates, between which the space for the slurry is formed normally comprise two types.
• the first type is intended to lead water out from the space during the dewatering phase through a first set of channels.
• pressurised air is led into the space through the dewatering channels for the drying of the material in the space.
• the pressurised air is also led in through a second set of channels in the second type of plate, the type known as "pressure plate".
• This configuration is required in order to provide the possibility of leading the different media in to and out from the space, but it has the disadvantage that when the pressurised air is led in during the pressurised air drying the pressurised air presses the water back into the space.
• the filling of the slurry takes place through an opening normally located at the upper part of the filter. At this opening, which leads the slurry in between two plates, the cloth is also pressed fixed between the plates during the compression of the filter cassette.
• the filling involves the filter cloth being worn by the solid particles that are present in the slurry, and the compression also involves a certain degree of wear.
• Each drying cycle which involves filling, dewatering and pressurised air drying, takes place several times each hour. This means that the cloths are worn relatively rapidly and must be exchanged, which results in high costs.
• the design of the filling openings in currently available filter plates is such that the outer corners of the space between two plates are not filled to the same degree as the remainder of the space.
• One aim of the present invention is to limit or fully eliminate these shortcomings, and to offer a cost-effective filter plate that gives a higher dewatering capacity and a longer lifetime for the filter cloths. These aims are achieved through a filter plate that demonstrates the characteristics and properties that are specified in the patent claims. An embodiment chosen as an example will be described below with reference to the attached drawings, of which:
• Figure 1 shows a number of filter plates together forming a pressurised air filter
• Figure 2 shows a cross-section of two filter plates placed together forming a space with filter cloths and rinsing nozzles
• FIG. 3 shows a suspension means
• Figure 4 shows an input nozzle
• Figure 5 shows schematically the input of slurry into the spaces between two filter plates
• Figure 6 shows schematically the dewatering phase and the drying phase in one direction
• Figure 7 shows schematically the dewatering phase and the drying phase in the other direction.
• the pressurised air filter 1 shown in Figure 1 comprises a number of filter plates
• Each filter plate 2 comprises a unit built as a module with a frame R on the two sides of and surrounding a base plate 3 with two short edges 4a, 4b along the x-direction and two long edges 5a, 5b along the y-direction.
• the base plate is preferably manufactured from highly resistant, acid-resistant stainless steel in order to keep the thickness of the plate at a minimum and in order to increase its corrosion- resistive properties.
• a rubber or plastic mat (not shown in the drawings) provided with studs or projections is glued or attached by another method to both sides of the base plate. Passages are formed between the studs or projections, the function of which will be described later.
• Two opposite edges of the base plate preferably the long edges, demonstrate protruding parts 6a, 6b, 7a, 7b in the form of lugs or extensions of area in order to offer space for openings that form channels T, W through the base plate and the frames along the z-direction when several filter plates are assembled together.
• the parts 6a, 6b are omitted in a second embodiment, whereby the openings are arranged in the lower side of the base plate in order to facilitate the removal of the filter plate from the pressurised air filter.
• the base plate may be provided with a stiffening member (not shown in the drawings) that extend along at least one of the edges of the plate perpendicular to the base plate, in order to improve the structural stability.
• the base plate and the frame in one embodiment are manufactured in one piece from plastic, with channels placed by moulding, milling or drilling or a combination of these methods.
• the base plate in another embodiment may be manufactured from plastic or from highly resistant steel with a plastic frame constructed as a module that forms a space for the slurry. It is an advantage if the parts of the frame are arranged with a slit that partially divides the piece of frame in its longitudinal direction.
• the pieces of frame are assembled with the aid of the slit onto the base plate through the slit being placed over the edge of the base plate whereby the pieces of frame surround the edges of the base plate and are attached with the aid of screws, bolts or similar fixing means, into the base plate. Sealing strips are arranged between the pieces of frame whereby leakage between the pieces of frame is prevented.
• protrusions 8 are arranged as shown in Figure 3 with which it is intended that the plate 2 should be suspended when the pressurised air filter is assembled.
• the filter plates 2 are suspended in such a manner that they slide along rails (not shown in the drawings) when the filter plates are manipulated in the direction towards and away from each other.
• the protrusions 8 comprise a fixing plate 8a provided with flanges, which fixing plate is intended to be attached to the long edges 5a and 5b of the base plate, one fixing plate attached at each long edge.
• a shaft 8b is mounted at the fixing plate, essentially perpendicular to the fixing plate.
• a support element 8c having the form of a sheath is threaded onto the shaft and is locked in place by a peg 8d, or similar, through the flange and the shaft.
• the support element demonstrates a plane surface 8e that is intended to make contact with the suspension rails (not shown in the drawing).
• the vertical axis of the filter plate coincides with the y-axis in the coordinate system specified in Figure 1 , with its origin denoted by the letter "O".
• the principal axis of the pressurised air filter in the same manner coincides with the z-axis.
• Each plate demonstrates a number of through openings 9 - 14, symmetrically located on each side of the space U of the filter plate, which openings form longitudinal channels when several plates are assembled, which channels can be opened and closed with the aid of valves X.
• the frame pieces are arranged with openings that coincide with the openings in the base plate when the pieces of frame are mounted on the base plate. The location of the openings offers, when several plates are mounted in contact with each other and with each plate being turned by 180 degrees around the y-axis, a pressurised air filter with alternate pressurised air drying, which prevents the water being pressed back into the space U when the pressurised air is to be led into the space.
• a filling opening P for slurry S is arranged in association with the space, and it is an advantage that this is located above the space.
• At least three openings 9 - 14 are located extending through the thickness of the plate and the frame on each side of the space: a drainage opening 9, 10 at the lower edge, and two pressurised air openings 11 , 12 and 13, 14 located at the upper edge of the plate. It is intended that the drainage openings 9, 10 lead filtrate water out through the lines W during the dewatering phase, and it is intended that the pressurised air openings 11 - 14 lead pressurised air in through the lines T during the pressurised air drying.
• This provides the advantage that one single type of plate can be used, through rotating alternate plates by 180 degrees around the y-axis when assembling the pressurised air filter.
• a principal line 15 is arranged from one member 11 of the pair of pressurised air openings 11 , 12 in the frame at the first long edge 5a of the plate, down to the closest of the drainage openings 9, while the second pressurised air opening 12 at the first long edge 5a of the plate does not have a connection to the principal line 15.
• a second main line 16 runs from one 13 of the second pair of pressurised air openings 13, 14 at the second long edge 5b of the plate to the same drainage opening 9, while the second pressurised air opening 14 at the second long edge 5b of the plate does not have a connection to the principal line 16.
• one of the drainage openings 10 and one 12, 14 of the pressurised air openings 11 - 14 arranged at the two long sides of the plate do not have direct connection with a principal line 15, 16; and only constitute a part of the pressure channels T and drainage channels W, respectively, these channels being formed at the upper and lower edges of the pressurised air filter when the filter plates are assembled into a pressurised air filter.
• Transverse channels 17 are arranged between the principal lines 15, 16 and the space U to lead the filtrate water through the line W from the space U to the principal lines 15, 16, and to lead pressurised air through the line T from the principal lines 15, 16 to the space U.
• the extent of the principal lines 15, 16 is such that three of the edges of the space are located in close connection with the principal lines, whereby the transverse channels create flow connection between the space and the principal lines.
• Plate number 2 in the series of plates is identical to plate number 1 , but it has been rotated 180 degrees around the y-axis.
• the drainage opening 9 that is in connection with the principal lines 15, 16 is thus located on the opposite side of the space U relative to plate number 1.
• the pressurised air openings 11 , 13 that are not in connection with the principal lines 15, 16 are connected to the pressurised air T. In this way, no pressurised air enters the principal lines 15, 16 or the space U, whereby the principal lines 15, 16 are used for drainage of the space U and leading the filtrate water away from the space through the principal lines to the drainage channels W.
• each plate is rotated either around the vertical axis, which coincides with the y-axis, or around the horizontal axis of the filter plate, which corresponds to the x-axis, or around the z-axis, which coincides with the central axis of the filter plate and the pressurised air filter relative to the subsequent plate, while the same alternately directed communication is achieved
• the filling opening P is arranged in connection with the upper part of the filter plate as shown in Figure 1 , for filling of slurry.
• a filling channel Pz is formed through the pressurised air filter when several filter plates are placed in contact with each other.
• a nozzle 18 in the form of a collar as shown in Figure 5 is located in the filling opening.
• the nozzle is composed of two parts A, B, which are fixed to each other by neighbouring filter plates.
• One part A is provided with a track 19 and the other part is provided with a flange 20 for the pressurised fitting together with each other.
• the nozzle has been designed with a number of flow spreaders 21a - 21f in the form of grooves for the better spreading of the slurry S and in order to avoid wear of the filter cloth 22.
• the first groove 21a of the first part A extends tangentially outwards from the nozzle essentially vertically and the locations of the subsequent grooves 21 b, 21c are rotated from tangential extension to essentially radial extension as the flow spreaders come closer to the horizontal axis of the nozzle.
• the grooves 21a - 21f are arranged radially outwards from the filling opening P over the region of the space U that is connected with the filling opening P. Since slurry is pumped in, it is spread over the complete area of the opening, but the flow spreaders 21a - 21f control the flow such that wear on the cloth 22 is avoided.
• a radial spreader surface 23 is arranged at the upper part of the nozzle, with a radius that corresponds with the design of the part with expanded area at the upper part of the base plate at the inlet opening.
• the filter cloth 22 is arranged at each filter plate 1 , as shown in Figure 2, and forms the limiting surfaces of the space U, whereby fluid in the slurry S can pass through the filter cloth while the solid particles in the slurry cannot pass.
• the filter cloth rests against the studs (not shown in the drawings) during the dewatering and the drying, whereby the passages between the studs allow the fluid to be led through the cloth and out from the space.
• the cloth is held in tension between a pair of holders 23 or ramps that slide along the same glide rails (not shown in the drawings) as the filter plates.
• the ramps are also provided with rinsing nozzles 24 for rinsing of the filter cloths during cleaning.
• the rinsing ramps are located at the short edges of the filter plates whereby the filter cloths are held in tension between two opposite rinsing ramps.
• the filter cloths are provided along their long edges with loops that are evenly spaced relative to each other, and the rinsing ramps are provided with corresponding hooks.
• a retainer in the form of a rod or a stick 25 is inserted into the loops of the filter cloth whereby the space between the loops coincides with the hooks of the rinsing ramps.
• the retainer is inserted behind the hooks whereby the cloth is held in tension transversely over the plates between the rinsing ramps.
• the plates numbered 1 , 3, 5, n, of the pressurised air filter that is formed from the plates placed in a line, through the principal lines 15, 16 into the space U, while the pressurised air openings 12, 14 in other plates, i.e. the plates with even numbers 2, 4, 6, n, at the same time constitute only a part of the pressure channels.
• Pressurised air is led in the first of the plates described, in which pressurised air is led into the spaces U through the principal channels and the transverse channels, through the pressure channels T and the principal lines 15, 16 into the space U where the slurry is located.
• the drainage openings 9 that form the drainage channel W into which the principal lines 15, 16 open out is closed in this state. This means that all pressurised air is led through alternate plates into the space.
• the pressurised air passes from the pressure channel T into the principal lines 15, 16 of plate number 1 , onwards through the transverse channels 17 through the filter cloth 22, and the slurry S passes out through the next filter cloth 22 of filter plate number 2, in which the principal lines 15, 16 communicate with the drainage channel W, whereby the pressurised air also aids during the dewatering phase.
• the fluid that is present in the slurry is in this manner driven out from the space both by run-off and with the aid of the pressurised air
• the supply of pressurised air through the pressure channels is closed and the filter plates are manipulated in a direction away from each other whereby the spaces between the filter plates open and the filter cakes can be removed.
• the plates are manipulated in the direction towards each other and are pressed together. Slurry is subsequently filled through the filling openings and the next drying cycle begins.
• This drying cycle is carried out in that the supply of pressurised air is switched to the other pair of pressure channels as shown in Figure 8. This means that compressed air is led into the filter plates with even numbers, i.e. numbers 2, 4, 6, n, whereby the second drainage channel is closed.
• the drainage channel is opened in those plates with uneven numbers, i.e.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Drying Of Solid Materials (AREA)
• Filtration Of Liquid (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=38006125

Family Applications (1)

Country Status (2)

Cited By (1)

Citations (5)

• 2005
  • 2005-10-31 SE SE0502410A patent/SE529120C2/sv not_active IP Right Cessation
• 2006
  • 2006-10-31 WO PCT/SE2006/001225 patent/WO2007053080A1/en active Application Filing

Patent Citations (5)

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