WO1996011046A1

WO1996011046A1 - Method and station for filtering a liquid or gas containing suspended matter

Info

Publication number: WO1996011046A1
Application number: PCT/FR1995/001290
Authority: WO
Inventors: Jacky Bonnin
Original assignee: Denitral S.A.
Priority date: 1994-10-05
Filing date: 1995-10-04
Publication date: 1996-04-18
Also published as: FR2725379B1; FR2725379A1; AU3656195A

Abstract

The filter station comprises a supply (78) of the liquid or gas to be treated, a filtering device (1) made of a cellulose sponge type resilient matter, and having one surface in contact with a perforated plate support (61), means for applying pressure on the surface of the filtering device (1) opposite the surface in contact with the perforated plate (61) to force liquid or gas through the filtering device (1) while compressing it, filtered-liquid discharging means (77) and means for discharging (79) the solids retained by the filtering device (1), and adapted for use when the filtering device (1) is decompressed. The filtering device is advantageously in the form of a cylinder (60) associated with means for rotating it about its axis (65) so as to centrifugally filter the suspended matter.

Description

LIQUID OR GAS FILTRATION SYSTEM

CONTAINING SUSPENSION MATERIAL AND METHOD

OF IMPLEMENTATION

The present invention relates to the general field of phase separation of a complex medium; it relates more particularly to an installation for filtering a liquid or a gas which contains suspended matter, as well as the process for implementing this installation.

There are many types of filtration systems suitable for separating particles or matter suspended in a liquid or a gas. The filtration operation makes it possible to concentrate the particles in order to obtain a solid or semi-solid by-product; the liquid or the gas is, itself, rid of all or part of the particles which it contained before filtration. Depending on the noble product that one wishes to collect, one works either in "concentration" mode, or in "clarification" mode.

The field of filtration is very large. It is nonetheless characterized by a permanent factor: the filter element over which the product to be filtered passes and which retains or separates the solid particles.

The filter is by definition a porous body _through which the fluid is passed. We know different types such as grids, fabrics, membranes, ceramics or others ... Their structure and their pore diameter are adapted according to the product or products that we want to separate and according to the desired degree of filtration.

However, in general, the finer the particles to be filtered, the less efficient the system, the more its capacity decreases, the more complex and expensive it is. Also, in many areas, _has ι perfect solution does not exist; this is the case, in particular, for the dewatering of sludge from treatment plants (fine particles of the bacteria type, present in considerable quantities and diluted in large volumes of water), for the filtration of cleaning liquids (on which recycling depends), for the dedusting of air, for the filtration of bio¬ products or even for the filtration of chemicals, agro-food, even pharmaceutical.

For these different areas, there are solutions but their constraints, their performance or their cost limit their use.

In an attempt to remedy these drawbacks, attempts have been made to use other types of filters. Thus, in document US-A-3 207 061, the filtration installation consists of a filtering member formed by a juxtaposition of segments of elastic spongy material on which the liquid to be treated is deposited. The segments of spongy material undergo successive operations of compression and decompression by means of rigid members which move parallel to their upper surface. During the decompression phases, the filter elements are filled with the liquid to be treated; during the compression phases, the rigid members force the passage of the liquid through the spongy material and they simultaneously scrape its upper surface to ensure the evacuation of the retained solid materials.

This type of installation does not offer optimal efficiency in terms of performance and longevity, in particular.

The present invention aims to propose _U does filtration plant which is very simple to implement and which has an interesting efficiency under difficult conditions and recognized delicate, that is to say for the treatment of liquids or gases loaded fine particles whose size _has ι is the micron or a few tens of microns.

This filtration installation is of the type comprising: - a supply of liquid or gas to treat, - a filtration member, or filter, of elastic spongy material of the cellulose sponge type, one of the faces of which is in contact with a support in the form of a perforated plate, - means capable of applying pressure to the face of the filtering member opposite to that in contact with said perforated plate, to force the liquid or the gas to pass through the filtering member while ensuring the compression of the latter, - means of evacuation and / or storage of the liquid or filtered gas, and - means for removing and / or storing the retained solids.

According to the invention, this installation includes means for ensuring the evacuation of the solids retained by the filtering member, adapted to be used during the decompression phases of said filtering member.

The use of an elastic spongy material as a filtering member ensures, by its macro and micro-porous structure, a very effective filtration of the particles which it is desired to separate. During the filtration operation, the material permeates the fluid; the solid particles retained penetrate a few millimeters into the spongy material or remain blocked on the surface and the filtered fluid passes through said material and can be recovered or stored downstream. The actual filtration phase is accompanied by compression of the elastic material. Thus, during the phase of return to stable position (decompression) the elastic spongy material expels or rejects towards the surface a large part of the solids which it retained in its porous network. The decompression operation makes it possible to "empty" the filter and the layer of solid or semi-solid material can be removed by any suitable means. The filter can then be used again with optimum efficiency. In the case of the treatment of a gaseous fluid, the Characteristics of the cellulose sponge-shaped filter will require the presence and maintenance of moisture to maintain the flexibility of the material.

The solid particles retained by the filter can be removed by scraper, vacuum or other means.

The means capable of applying pressure to the upper surface of the filtering member can consist of a pressing roller driven back and forth parallel to the plane of said filtering member. It is also possible to use means of the suction or pneumatic thrust type, or else to use centrifugal force.

According to a particularly advantageous embodiment, the filtration installation comprises:

a filter drum consisting of a filter member of generally cylindrical shape, the outer face of which is in contact with a perforated cylinder,

a fixed casing surrounding said filter drum, means for driving the filter drum in rotation around its axis, a supply of fluid to be treated, disposed inside the drum,

means for evacuating the filtered fluid, at the level of the fixed casing, and

- Means for ensuring the evacuation of the solids retained by the filter.

The invention also relates to the filtration process for the implementation of the installation defined above.

This process consists in passing the liquid or the gas through the filtering member in elastic spongy material, while ensuring the compression of the latter, then in carrying out a complementary operation of evacuation of the solids retained by the filtering member, which operation is carried out after decompression of said filtering member and return to its initial stable position. When using a filter drum associated with a principle of filtration by centrifugal force, the actual filtration operation can be carried out at a fast rotation speed and the solids evacuation operation at a slow rotation speed of the drum, after decompression of the filtering member.

Other characteristics will emerge from the following description of different particular embodiments, given by way of examples and shown in the appended drawings in which:

- Figures la. to the. illustrate the different stages of the filtration process according to the present invention; - Figure 2 is a schematic representation of a possible embodiment of the filtration installation;

- Figure 3 is a longitudinal sectional view of another type of filtration installation;

- Figure 4 is a section of Figure 3 along 4-4; Figure 5 shows the installation of Figures 3 and 4 during operation and in the compression phase;

- Figure 6 is a sectional view of Figure 5 along 6-6; FIG. 7 shows the same installation, in the decompression phase;

- Figure 8 is a cross-sectional view of Figure 7 along 8-8; FIG. 9 illustrates a variant of the filtration drum adapted to favor the decompression operation of the filter; Figure 10 is a schematic representation, _in longitudinal section, of another possible embodiment of the filtration installation; Figure 11 is an end view of the installation shown in Figure 10; - Figure 12 is a schematic view of another embodiment of the filtration installation; FIG. 13 is an end view of the installation shown in FIG. 12.

In the installation and the filtration process according to the invention, the filtering member used consists of an elastic sponge-like material, sponge type, and more particularly of cellulose sponge. The thickness of the material is chosen according to the type and degree of filtration desired.

As an indication, for the treatment of sludge from sewage treatment plants, it is advantageous to use a brown cellulosic sponge, of heavy work quality, distributed by the company FACEL, 25190 St-HYPOLYT

- FRANCE.

The thicknesses chosen can be of the order of 3 to 12 cm. As an indication, a material of this type which has a thickness of 12 cm at rest can be flattened until a thickness of the order of 5 cm is obtained.

The composition of this material, for 1 gram of dry matter, is as follows:

- cellulose: 0.84 g

- flax fibers: 0.14 g

- coloring pigment: 0.003 g - elemental composition: magnesium: 52 mg; nitrogen 0.470 mg; potassium: 0.343 mg; copper: 0.183 mg zinc: 0.118 mg; phosphorus: 0.010 mg; chromium less than or equal to 0.005 mg; lead: less than or equal to 0.005 mg.

As shown in FIG. 1, filtration on a sponge 1 consists in supplying the fluid to be filtered 2 at the surface (FIG. La_) and causing, in one way or another (pressure, suction, centrifugal force ...), a flattening movement (figure l_b) which forces the fluid to pass through the sponge. The solid particles 3 are concentrated on the surface; clogging or saturation are only very gradual. The fluid filtered 4 passes through the sponge; it can be evacuated or recovered by any appropriate means.

When the layer of solid matter begins to limit the effectiveness of the filter, the compression of the sponge is stopped: we wait for its return to the initial stable position and the retained solids are evacuated by any appropriate means (Figure l.c). The filtration system can then be used again. This type of installation has the great advantage of using exclusively physical means to achieve effective separation of the different phases. The return to the stable position makes it possible to expel towards the exterior a part of the solids blocked in the surface pores of the spongy material, before carrying out their evacuation. This feature optimizes the recovery of the cake of solid or semi-solid materials.

The configuration of the installation and the implementation process may vary, in particular depending on the fluids (liquid or gas) to be filtered and the source of the flattening / relaxation movement used. In particular, the times of the filtration and evacuation phases of the retained solids will be adapted case by case. Also, the cycle which includes the supply of product to be filtered, the movements of the sponge and the collection of the separated particles can be discontinuous, semi-continuous or continuous, depending on the means and the process used.

Applied on sludge from treatment plants, this technique makes it possible to separate all of the particles (essentially bacteria) and to obtain a pasty or solid effluent, on the other hand.

FIG. 2 shows a complete filtration installation using the principle which has just been described.

This installation comprises a cellulose sponge plate 1 whose thickness is close to 12 cm, placed horizontally on a perforated plate 6 which serves as a support. This assembly is arranged above a tank 7 with a slightly conical bottom, the outlet 8 of which is connected to a vacuum pump 9. A steamroller 10 is positioned on the upstream surface of the sponge plate 1 and it is driven back and forth parallel to the plane of said plate

I. This movement, according to the double orientation arrow

II, is produced by means of geared motor 12 adapted. The perforated plate 6 consists of a sheet whose perforation rate is as high as possible in conjunction with the compression means used.

The width of the steamroller 10 corresponds substantially to that of the sponge plate 1; on the other hand, the reciprocating back and forth movement allows the roller 10 to circulate over the entire length of said plate 1.

A pump 15 supplies the fluid to be filtered 2 (a liquid effluent for example) by means of a ramp 17 placed just in front of the roller 10. The ramp 17 is integral with the structure which carries the steamroller 10 and it moves in the same movement as the latter by means of the geared motor means 12.

The installation also includes a device 18 for suctioning the dehydrated particles retained by the filter. This device is arranged behind the roller 10 and is connected to the vacuum _pump 9. The latter is associated with a set of solenoid valves 19 and 20 which permit the alternative suction the tank bottom 7 and by the device suction 18. The filtered effluent 4 is stored in a tank 21 and the dewatered sludge 3 is partitioned in a separate enclosure 22.

In addition, the installation can be completed by a device 24 for supplying hot air to the surface of the sponge 1, disposed behind the roller. compressor 10 at the suction means 18. The hot air can be that produced by the vacuum pump 9; it completes the dewatering of the sludge retained on the upstream side of the filter. The suction device 18 for the dehydrated particles and the hot air supply device 24 are secured to the supporting structure of the steamroller 10 and driven by the gearmotors 12.

The movement of the roller 10 on the surface of the sponge ensures compression immediately followed by a relaxation phase (decompression). The effluent can pass through the filter 1 by simple gravity, after impregnation; compression makes this easier. Just after the passage of the roller 10, the sponge 1 resumes its initial volume by rejecting at the surface the particles which have previously penetrated it at the surface. The speed of movement of the roller 10 is chosen as a function of the desired filtration characteristics, as are the cycles of supply of effluent to be treated and suction of the dehydrated sludge.

A similar design of installation can consist in replacing the roller 10 by a pressure plate animated with a vertical movement. The means for supplying fluid and for suction or recovery of the retained solid particles will then be adapted accordingly.

Figures 3 to 8 show another type of filtration installation design incorporating the principle of separation according to the present invention and using centrifugal force.

This installation is particularly suitable for the treatment of liquid effluents. It consists of a filter drum 30 whose horizontal axis 31 is supported by bearings 32. The drum 30 is rotated by motor means 33. The bearings 32 and the motorization 33 are carried by a frame 34.

The drum 30 consists of a cylindrical filt 1 of elastic spongy material, ty cellulose sponge. This filter is sandwiched between two perforated cylinders, one external 35 the other internal 36, between which it is packed or prestressed. For purely indicative purposes, the thickness of the sponge 1 can be of the order of 12 cm, at rest the space between the two perforated cylinders 35 and 3 being of the order of 7 to 8 cm. These cylinders 35 and 3 are obtained from sheets with the highest possible perforation rate.

The filtering complex consisting of perforated cylinders 35 and 36 and of the cellulosic sponge 1 are mounted in cantilever on the axis 31 by means of a carrier disc 37 located on the side of the motorization 33. At the level on the opposite side, the edge of the sponge 1 is masked by a simple metal ring 3 allowing access from the outside to the axial vacuum space 40 delimited by the internal cylinder 36. The filter drum 30 is covered by a fixed casing 4 of slightly larger diameter. This casing 41 has an axial opening 42 allowing access from the outside to the axial void space 40.

Under the axis 31 of the drum 30, we notice the presence of a ramp 43 for supplying the filtering fluid. This ramp 43 comes from the outside; It extends in the axial void space 40 passing through the opening 42 of the casing 41 and it is mounted overhang on the chassis 34 of the installation. E lower part, the casing has an opening 4 intended for the evacuation of the filtered fluid.

In FIGS. 3 and 4, we also note the presence of a fixed longitudinal scraper 45 carried by the card 41 and which extends in the axial empty space 40, e high part, against the internal perforated cylinder 36 This scraper 45 cooperates with a return cone 4 arranged around the axis 31 to ensure the evacuation solids retained by the filter to a recovery chute 47.

The operation of this installation will now be explained in conjunction with FIGS. 5 to 8.

As shown in FIGS. 5 and 6, the filtration operation is carried out by rotating the drum 30 around its axis 31 by means of the motorization 33. The speed of rotation applied depends on the type of installation and desired quality of filtration. It can be adapted to the desired crushing thickness of the filter.

As an indication, for sludges from treatment plants or the like, we will seek to achieve accelerations of the order of 400 to 500 g at the periphery. For such values and for a drum whose diameter is close to 700 mm, the speed of rotation at the level of the axis will be of the order of 1000 revolutions / min.

This rotation compresses the filter 1 against the external perforated cylinder 35 by centrifugal force. The drum 30 is supplied with fluid to be treated 2 and the centrifugal force forces said fluid to pass through the sponge 1. The filtered fluid 4 is collected by the casing 41 and it is evacuated by simple gravity at its low orifice 44.

Despite the prestressing of the filter 1 between the two perforated cylinders 35 and 36, the rotation of the drum 30 is preferably adapted to detach the upstream face of the filter from its support cylinder 36.

This compression operation is carried out as long as the filtration member operates efficiently. When the solid materials have to be removed, the fluid supply 2 is stopped and the speed of rotation of the drum 30 is lowered so as to allow the filter 1 to return to its initial size, pressing on the internal cylinder 36. The decompression and this contact against the perforated cylinder 36 cause the expulsion of the solid materials 3 deposited on the sponge. This configuration is visible in Figures 7 and 8. The scraper 45 can then play its full role; it takes off the dehydrated solid materials from the surface of the sponge 1 and from the perforated cylinder 36 so as to allow them to be taken up by the orientation cone 46. At the end of the drum 30, the solid materials 3 are taken up by the chute 4 to be evacuated to the outside where they will be stored.

In accordance with the diagrammatic representation of FIG. 9, the external perforated cylinder 35 can consist of two half-shells 35 ′ and 35 secured to each other by return means 5 (springs, pneumatic or hydraulic cylinders, etc.) The cylinder 35 is mounted floating on the filter 1 This feature improves the décolmatag d _u when the filter or the phase (s) decompression Indeed, during the filtration phase, the centrifugal forced causes the separation of the two deπi shells; when slowing the springs cylinders 50 o electroplate the half-shells against the filter _which gives an extra al decompression force to remove the retained solids.

The compression and decompression cycles are adapted according to the characteristics of the installation and according to the fluid treated. As an example, a filtration drum of this structure having a diameter of 0.5 m and a length of 0.4 can filter sludge from treatment plants 5% by weight of dry matter, at a flow rate of l 'order of 300 liters / hour. The pasty or solid product collected consists of dry matter at a rate of 25% by weight.

Figures 10 and 11 illustrate a derivative embodiment incorporating the principle of the tambou filter rotated to activate the centrifugal force.

In this embodiment, the filter drum 60 consists of a cylindrical filter 1 made of cellulose sponge (thickness 5 cm), the outer face of which is in contact with a perforated cylinder 61. The perforated cylinder 61 is fixed at its ends, on two solid cylindrical rings 62 and 63.

The drum 60 is mounted in cantilever on the horizontal axis of rotation 65 by means of a carrier disc 66 associated with a hub 67 located on the side of the motorization 68. The carrier disc 66 is secured to the cylindrical end ring 63. At the level of the cantilever face of the drum 60, the edge of the sponge 1 is masked by a metal crown 69.

The sponge filter 1 maintains itself against the perforated plate 61; its ends are slightly set back from the carrier disc 66 and the crown 69 to maintain a slight empty space on both sides.

The motorized axis 65 is mounted on bearings 70 and 71 secured to the frame 72. The motorization 68 drives the pulley 73 secured to the end of the shaft 65 by means of the belts 74.

The drum 60 is covered by a fixed casing 75 provided with a front access door 76, in front of the bearing 71. The bottom of the casing 73 has a conical shape; it is provided with an orifice 77 which allows the evacuation of the filtered fluid.

In FIGS. 10 and 11, we note the supply of fluid to be filtered which is in the form of a longitudinal ramp 78, as well as the evacuation device 79 of the solids retained by the filter 1.

This evacuation device 79 consists of a longitudinal scraper 80 associated with a horizontal receiving chute 82 in which is disposed an extraction worm 83. The assembly is cantilevered on a pivoting support 84 secured to the bearing 71 and subjected to the action of a control jack 85 to occupy an active position and a position inactive detailed below.

The scraper 80, the chute 82 and the screw 83 extend over the entire length of the drum 60, inside the latter, from the bearing 71 to the carrier disc 66. Note the presence of a chute vertical discharge 86 arranged outside the drum 60, at the end of the horizontal chute 82. Note also the presence of a driving roller 88 at the end of the extraction screw 83 which is located inside the drum 60.

On the other hand, we note the presence of an auxiliary motorization 89 provided with a driving roller 90 capable of coming to be applied against the pulley 73 situated at the end of the axis 65. This auxiliary motorization 89, 90 is mounted on a pivoting support controlled by a jack which have not been shown to simplify the representation. As will be seen below, it is used during the decompression phases of the filter 1, for the operations of removing the retained solids.

The main motorization 68 allows the filter drum 60 to be driven at rapid speeds (400 to 500 g on the periphery). The auxiliary motorization 89 is adapted to ensure its drive at slow speed, of the order of a few revolutions / min.

The filtration of the fluid coming from the feed ramp 78 is carried out by driving the filter drum 60 at high speed, by means of the main motorization 68. The cylindrical filter 1 compresses against the perforated plate 61; the filtered fluid is discharged through the orifice 77 and the solid materials accumulate on the inside of the sponge. 46 PC-7FR95 / 01290

1 5

When it is desired to evacuate this layer of solid or semi-solid matter, the main motorization 68 is stopped and the arrival of fluid at the level of the ramp 78. The sponge 1 decompresses and returns to its initial stable position.

The roller 90 of the auxiliary motorization 89 is applied against the pulley 73 to ensure the rotation drive of the drum 60 at low speed; simultaneously or shortly afterwards, the jack 85 is actuated to apply the scraper 80 against the inner face of the sponge 1, by means of the pivoting support 84.

The outer end of the longitudinal chute 82 has an evacuation orifice 91. During the pivoting operation of the evacuation device 79, this orifice 91 comes to be placed above the vertical trough 86. On the other hand, the roller 88 located at the end of the endless screw 83 is applied against the cylindrical ring 63, outside the size of the filter member 1. This roller 88 ensures the rotational drive of the is endless 83 through the movement of the drum 60.

The fixed scraper 80 takes off the solid materials from the surface of the sponge 1; the detached materials fall into the receiving chute 82 and they are entrained by the screw 83 towards the evacuation chute 86.

Once the filtering member 1 has been cleaned, the evacuation device 79 and the motorization 89 are returned to the inactive position and another filtration cycle can start.

For certain particular applications, and essentially for yield problems, it may be necessary to limit the filtration characteristics of the fluid and to complete the installation with additional settling tanks. In this case, one can advantageously provide a supply of fluid to be treated in the filter drum bottom, in front of the carrier disc 66, a few leakage orifices regularly distributed over the cylindrical ring 62. Thus, during operation in filtration mode, most of the fluid is filtered by the sponge 1; the rest, partially filtered, will be evacuated by the leakage orifices, after passage between the end of the filter 1 and the metallic one 69. On the other hand, if one wishes to separate several types of suspended solids of different density present in the fluid to be treated, it is possible to incline the axis 65 of the filtering drum 60 by a few degrees relative to the horizontal. The separation between residues on the inner face of the sponge is then carried out by simple gravity and these residues are individually screened by appropriate evacuation means. This characteristic could in particular be envisaged for the separation of grease and sandy residues in the filtration plants of slaughterhouse effluents.

FIGS. 12 and 13 illustrate another possible embodiment of the filtration installation, with different means for the evacuation of the solid materials retained by the filter.

In this embodiment, the filter drum

95 consists of a cylindrical filter 1 made of cellulose sponge, pressed against an outer perforated cylinder 96.

At one end, the perforated cylinder

96 is secured to a cylindrical ring 97 which extends a carrier disc 98 mounted on the axis of rotation 99 via the hub 100. At its other end, the perforated cylinder 96 is secured to a cylindrical ring 101 which extends a segment annular 103 mounted on the axis of rotation 99 pa by means of four spokes 104 and a hub 1 05.

Thus, for this exemplary embodiment, the filter drum is supported by the central axis at its two ends. It is no longer in overhang which allows obtaining a more rigid structure.

The axis 99 is mounted on bearings 106 and 107. It is rotated by means of an end pulley 108 associated with drive means, not shown, located on the side of the carrier disc 98.

The drum 95 is covered by a casing 109 provided with an outlet orifice 110 for the filtered fluid, at its conical bottom 111.

This assembly is carried by a secondary chassis 115 itself pivotally mounted on a main chassis 116 by means of a horizontal pivot axis 117. Two double-acting hydraulic cylinders 118 connect the main chassis 116 and the secondary chassis 115 to control the pivoting of the latter around the axis 117.

At the drive means, the secondary chassis includes a support stop 120 which cooperates with a receiving cradle 121 arranged on the main chassis 116. These support means 120 and 121 can be associated with a removable locking device.

On the secondary chassis 115, we also note the presence of a vibrator device 122 whose function will be explained below.

The fluid to be treated is supplied at the axis 99, via an inlet pipe 124 and a rotating joint 125. The axis 99 has a central orifice 126 which opens out at the interior of the filter drum 95; to limit the length of the axial bore, the fluid supply is taken up by external pipes 130.

As in the previous example, illustrated in FIGS. 10 and 11, the rotary drive of the filter drum consists of a main motor at high speed for the phases of filtration, and an auxiliary motor with slow speed for the solid matter evacuation phases.

For the filtration phases, the drum 9 is rotated at high speed and the interior of the drum is supplied with filter fluid via the conduits 130. The sponge 1 s compresses and acts as a filtering member. ; the filtrate is collected by the discharge orifice 11 and the solid or semi-solid materials accumulate on the interior surface of the sponge.

During the filtration phases, the axis 99 of the drum 95 is horizontal or substantially horizontal; the secondary chassis 115 is secured to the main chassis via - the pivot axis 117 of the support means 120 and 121, and - double-acting hydraulic cylinders 118 which operate under traction.

The solids retained by the filter are evacuated after the main engine and the fluid supply to be treated have stopped. The auxiliary motor at slow speed is implemented, the vibrating device 122 is actuated and the secondary chassis 115 is rocked around the pivot axis 117 by means of the hydraulic cylinders 118. This pivoting takes place at a slope of around 45 °, in the direction of evacuation of solid matter through the spaces between the end spokes 104. The slow speed rotation of the drum associated with the vibrating device 122 facilitates the separation of the solid matter from the sponge filter 1. The solids are extracted from the filter drum by simple gravity. If necessary, you can use a complementary internal scraper or an auxiliary unclogging device, of the air jet type for example.

Under the filter drum 95, there is a device for recovering and storing materials solids discharged.

To allow a new filtration cycle, the drum is replaced in a horizontal position and locked on the main frame. The slow motorization is disconnected from the drive axis 99.

Claims

- CLAIMS - 1.- Installation for filtration of a liquid o a gas containing suspended matter, which installation includes: - a supply (17, 43, 78, 130) of liquid o gas to be treated, a filtering member (1) in elastic spongy material, of the cellulose sponge type, one of the faces of which is in contact with a support in the form of a perforated plate (6, 35, 61, 96), means capable of applying pressure to the face the filter member opposite that in contact with said perforated plate, to force the liquid or the gas to pass through the filter member (1) while ensuring the compression of the latter,

- means for removing and / or storing the filtered liquid or gas (2), and

- means of evacuation and / or storage of retained solids (3), characterized in that it comprises means for ensuring the evacuation of solids (3) retained by the filtering member (1), adapted to be implemented during the decompression phases of said filtering member.

2.- Installation according to claim 1, characterized in that the solids evacuation means (3) retained by the filter (1) consist of a suction system (24).

3.- Installation according to claim 1, characterized in that the solids removal means (3) retained by the filter (1) comprise a scraper device (45, 80).

4.- Installation according to any one of claims 1 to 3, characterized in that the means capable of applying pressure to the upper surface of the filter member (1) consist of a pressure roller (10) driven by a back and forth movement parallel to the plane of said filter member (1).

5.- Installation according to any one of Claims 1 to 3, characterized in that the means capable of applying pressure to the surface of the filtering member (1) consist of means of the pneumatic suction or thrust type. 5 6.- Installation according to any one of claims 1 to 3, characterized in that the means capable of applying pressure to the surface of the filter member (1) consist of means of the centrifugal force type. 7. Installation according to claim 6, characterized in that it comprises a filtering drum (30, 60, 95) consisting of: a filtering member (1) of generally cylindrical shape whose external face is in contact with a perforated cylinder (35, 61, 96),

- a fixed casing (41, 75, 109) surrounding said drum filter, drive means in rotation (33, 68-89) of said filter drum about its axis, 20 _ _U not supply fluid to be treated (43, 78, 130), arranged inside the filter drum, means for evacuating (44, 77, 110) the filtered fluid, at the level of the fixed casing, and means for ensuring the evacuation of solids 2 (3) retained by the filter (1).

8.- Installation according to claim 7, characterized in that it comprises a filter drum (30, 60, 95) whose longitudinal axis (31, 65, 99) is horizontal or substantially horizontal. ^JU 9, _ Installation according to any one of claims 7 or 8, characterized in that it comprises a filter drum (30) consisting of a cylindrical filter member (1) sandwiched between two perforated cylinders, one external (35) and the other internal ³⁵ (36).

10.- Installation according to claim 9, characterized in that it comprises a filter member (1) prestressed between the two perforated cylinders (35, 36).

11.- Installation according to any one of claims 7 to 10, characterized in that it comprises means for discharging the solids (3 retained by the filter drum consisting of a scraping device (45, 80) of the internal face of the filtering member (1), or of the internal perforated cylinder (36) as the case may be, which scraper device is associated with means (46-47, 82-83) for collecting said solids (3) and for extract them from said filter drum.

12.- Installation according to claim 11 characterized in that it comprises a scraping device (80) associated with a receiving chute (82 in which is disposed a screw without extraction fi (83), all of these evacuation means having the possibility of occupying two positions inside the filter drum (60), one inactive in which the scraping member (80 is distant from the drum, for rest or filtration phases, and the other active in which the scraping member (80) is in contact with the internal face of said drum (60), to ensure the separation of solids (3) retained by the filtering member (1), and that , in the active position, the worm (83 is rotated by a roller (88) in contact with the filter drum (60) itself driven by rotation by suitable motor means (89).

13.- Installation according to any one of claims 7 to 10, characterized in that it comprises a filter drum (95) pivotally mounted on an axis (117) secured to a fixed frame (116) to allow evacuation solids (3) retained by the filter member (1), by simple gravity.

14.- Installation according to claim 13 characterized in that it comprises a filter drum (95) mounted on its axis of rotation (99) pa through a rigid disc (98) at one of its ends, and via spokes (104) at the other end to obtain a rigid assembly while allowing the evacuation of solids (3) during the tilting operation, said installation also comprising an axial supply ( 124, 126, 130) in fluid to be treated, connected by a rotary joint (125).

15.- Installation according to any one of claims 13 or 14, characterized in that it comprises a vibrator device (122) to promote the separation of the solids (3) retained by the filtering member (1).

16.- Installation according to any one of claims 7 to 15, characterized in that it comprises an external perforated cylinder (61, 96) supported by two rigid cylindrical rings (62-63, 97-101) at each of its ends, at least one of these rings having regularly distributed leakage orifices. 17.- Installation according to any one of claims 7 to 16, characterized in that it comprises a main motorization (68) for ensuring the rapid rotation of the filter drum during filtration operations, and an auxiliary motorization ( 89) for the slow rotation of said drum during the evacuation phases of the retained solids.

18.- A method of filtering a liquid or a gas containing suspended matter, for the implementation of the installation according to any one of claims 1 to 17, characterized in that it consists in making pass said liquid or gas through the filtering member (1) in elastic spongy material, while ensuring the compression of the latter, then to carry out the evacuation of the solids (3) retained by said filtering member (1), after decompression of said filter member and return to its initial stable position. 19.- Filtration method according to claim 18, for the implementation of the salt installation any of claims 7 to 17, characterized in that it consists in carrying out filtration by u rapid rotation of the drum filter (30, 6 95), and perform the operation of removing the solid (3) by slowly rotating said drum, after decompression of the filter member (1).