IT202100003086A1 - PLANT AND PROCESS FOR FILTRATION OF FLUIDS - Google Patents

Description

TITLE: FLUIDS FILTRATION PLANT AND PROCEDURE

FIELD OF TECHNIQUE

The invention belongs to the sector of filtration of lubricants and/or cooling fluids with unit? filtration using filter paper ribbons and the precoating and body-feed technique. These cooling and lubricating fluids come in particular from iron and steel or metallurgical plants, such as rolling mills. Filtration is necessary to recover the fluids used as cooling/lubricants. Applications in the field of water treatment and purification in general are also conceivable.

STATE OF THE ART

Rolling, in particular of aluminum and its alloys, involves the use of kerosene-based lubricating oils instead of emulsified water, which also act as cooling. The kerosene avoids unpleasant aspects of surface oxidation of the aluminum, which turns out to be decidedly more? reactive of steel in contact with water. This lubricant has for? a higher cost than that of? water, for which ? important to be able to filter it and reuse it as much as possible.

In the state of the art, filtration takes place through devices shaped like ?towers? of trays containing filter earths (or filter cakes), through which the dirty lubricant or cooling fluid is pumped under pressure. These earths are wrapped in layers of a particular absorbent cloth, generally referred to as filter paper, which acts as an additional filter and earth support and which must be changed regularly.

These towers have a high cost of preparation as they are made from special grid-shaped castings which are very expensive. Column or tower filters are also inconvenient from an operational point of view, given that they all work together and therefore when the sand is cleaned and the paper replaced, they must be stopped together and therefore production must be interrupted if have reserves of clean lubricant.

Do tower systems provide for a plurality? reels of fresh paper that feed the individual units? of trays arranged in a tower one above the other. After cleaning the individual units? (removal of lands that are no longer usable), is the dirty paper ? pulled out of the tower by pulling/dragging new paper into the system and pulling out the dirty one. Furthermore, the individual units? are pressed during filtration: there? not so much to wring the lands and to bring down the clean fluid, but to seal the unit? between them. In an exemplary application the pressures reach around 40 tons. Regularly c?? the need? to stop the machine to carry out the cleaning and the stop time? of about 20 minutes, this implies having to have a quantity? of coolant or clean lubricant reserve, cos? to be able to continue production without stopping the rolling mill. Conversely, as seen, the production line must be stopped. The cycle time of a standard filter varies from approximately 8 hours to 24 hours.

In addition to the high cost of tower filters related to their construction, the manipulation and pressure system of the plates in the tower? complex and since there is a plurality? of components to maintain that may be subject to failure, is overall very expensive.

A vertical filtration device ? described in US patent US 4,292,173 in which several units? of filtration are held together by the movement of a single piston, fluid and earth are introduced together. Further plate filters arranged in a columnar manner are described in documents US 4, 329,228, US 4,869,834 and US 5,238,584. No document yes ? posed the problem of avoiding the simultaneous use of plates or avoiding the shutdown of the filtration system and consequently of the rolling mill. The state of the art is mainly dedicated to the recovery of the filtering material, as for example also the document US 5,258,119.

EXHIBITION OF THE INVENTION

The invention aims to overcome the aforementioned drawbacks and to propose a new filter configuration or a filtration system and process which avoids the filtration and production stoppages of systems that use the cooling fluid or the lubricant in the phases maintenance, cleaning or repair of individual units? of filtration. Another purpose of the invention ? that of proposing a plant and a filtration procedure which allows to operate high pressures, even four times compared to the state of the art, on the filter paper, increasing the filtration efficiency.

Another purpose of the invention? to provide a plant and a filtration process that is more? economical compared to state-of-the-art systems, which allows savings in particular in terms of material requirements and which reduces the volume of reserve fluid required, which also further avoids the use of complex movement machinery, such as hydraulic cylinders, for the realization of the filter chamber hermetically closed, but which at the same time exerts sufficient pressure on the filter paper and possibly on the other filter media.

Further objects and advantages of the invention result from the following description.

In a first aspect of the invention, the aim is achieved by means of a filtration system for fluids, in particular cooling fluids and/or lubricants comprising:

(a) one or more tunnel each divided into an upper part and a lower part, equipped with at least one inlet, in particular in the upper part, and at least one outlet, in particular in the lower part, for respectively introducing the fluid to be filtered and for extracting the fluid filtered, in which each tunnel has on each end? a hermetically closable opening for the inlet and outlet of a filter medium, in particular filter paper;

(b) a frame to house said/s one or more? tunnel;

(c) a permeable support at the bottom of each tunnel for supporting the filter medium, especially the filter paper;

(d) a group of valves for each tunnel, configurable to isolate the tunnel from fluid flows entering and/or leaving it.

The horizontal development of the filtering chambers according to the invention envisages having the cleaning surface distributable over a smaller number of floors, thus allowing to reduce the frequency of changing the filter medium. Furthermore, ? Is it possible to arrange the filters in parallel, stopping only one filter (tunnel) at a time and working in the meantime with the others, to maintain cos? a productivity? in terms of coolant or clean lubricant recovered greater. The proposed plant? suitable for filtering fluids in general, in particular cooling and lubricating fluids, such as lubricating oils.

The plant according to the invention avoids the use of complex devices to create pressure on the filter medium and create the closed filter chamber, which is not created again each time by the compression of plates, but which is? already configured in the structure of a tunnel in the form of an oblong carcass.

The division into two parts ? also understood as a virtual subdivision, it is not necessarily a matter of two physically separate parts, even if this is? the preferred variant to simplify production and maintenance and the use of the tunnel in general. Advantageously, the two parts are divided by a horizontal longitudinal section of the tunnel. The term ?horizontal? refers to the fact that the section plane ? parallel to the tunnel installation plane.

The two openings at the ends? of the tunnel are used, in the opening, to pass the filter medium, in particular the filter paper, the cio? to let the clean filter paper enter, for example from the respective rollers and to let the dirty filter paper come out from the opposite side, which preferably will be? wound on other rolls. Several paper passing systems are widely known in the state of the art, so such as methods and appliances for eventually removing the filter cake from the paper. A new paper tape can easily be introduced into the tunnel, for example by attaching it to a plate and passing it through the tunnel. Even supports can cos? be introduced or replaced.

Advantageously, the tunnels are also equipped with one or more? inspection openings, especially in the upper part of the tunnel, to assess the condition of the filter paper, identify any clogging problems, etc.

The frame, preferably, pu? contain shelves or support structures for a variable number of tunnels, for example a number of four shelves for four tunnels. An assembly in frames with shelves facilitates any removal of a tunnel for its maintenance, but also access to the tunnel itself without detaching it from the chassis. Obviously, the expert identifies types of frames with his general knowledge.

An advantageous form of inlet for introducing the lubricant or cooling fluid to be filtered into the system ? a perforated tube, or a distributor tube, with a plurality? of holes, which extends inside the tunnel along its longitudinal extension.

In a variant of the invention, the lower part of the tunnel has a channel in its bottom, for example with a square or triangular section, for collecting the filtered fluid. Other section shapes are conceivable. The bottom itself can, for example, be reinforced by the presence of a plurality of of C-profiles or ribs. Compared to plate filters, as known from the state of the art, much higher pressures can be reached. high, even up to for example about 10 bar.

The filter medium can be of various kinds, but particularly ? preferred filter paper. The filter paper can be of various materials, not just paper, cio? cellulose, but also of other natural or synthetic polymeric materials and materials of the non-woven type. The list is not ? exhaustive. With the term ?filter paper? means any sheet, usually in the form of a ribbon or sheet, suitable for filtering a fluid. The person expert in the field easily chooses the most suitable one from the cards available on the market. suitable for its fluid and the particles contained therein to be separated. Reinforcing ribs or profiles may also be present on the structure forming the upper part of the tunnel.

In a tunnel according to the invention pressures of around 2.5 bar are typically obtainable, sufficient to press the filtering medium against its support.

The support can have various shapes, and the conformation in grids or nets, usually metallic, is particularly preferable. In a preferred variant of the invention, the support is a combination of a common grid and a mesh, for example made of stainless steel, superimposed, the mesh being placed on the filter paper side.

The support can be built from a plurality? of adjacent grates, standard grates available on the market often have a length of 2m.

Preferred forms of the implant according to the invention have one or more? air vents to eliminate, during the filling of the initially empty tunnel with the fluid to be treated, the air trapped in the upper part of the tunnel.

A structure of the filtration system in the form of individual tunnels allows for the separate management of each tunnel, not requiring the union of a series of plates to create the filtering chamber which can then only be separated together, but not individually.

The oblong shape of the filter and the force it exerts thus? the fluid to be filtered on the filter medium do not require the application of high forces on the structures that delimit the filtration chamber, ie? the walls of the tunnel. In a preferred variant of the invention, said/s one or more? Tunnels can/can therefore be manufactured from sheet metal, preferably reinforced by ribs or profiles in the structure. The structure itself should not exert force on the filter medium. State-of-the-art filter tower plates are often made from aluminum, no longer? necessary for the tunnels according to the invention, how is the necessity eliminated? to work the plates in a special way and to check them frequently. Ribs or profiles can be added to the tunnel walls, not only at the bottom, but also at the top, to further reinforce or even save material for the basic structure.

The replacement of filtration towers with the tunnel system according to the invention allows the reduction of costs to less than a third.

A typical tunnel length ? of 6 m. With a width of 1.5 m, a total filtration section of 9 m<2> is obtained. A typical height ? of about 0.50 m.

In order to keep the filter paper leaning against the support, the filtration plant according to the invention in a particularly preferred variant comprises in each tunnel a frame, preferably metallic, placed in a way that can be lifted and lowered above said support. During filtering, the fluid exerts a high pressure which presses on the supports of the filtering medium and on additional filtering materials that may be present, such as diatomaceous earth placed on filter paper: therefore? such a frame? sufficient to press the filter medium with its own weight on its support and to prevent its movement during the initial stage of filtration and lateral leaks and drips. This frame also serves as a containment element for the fluid and possibly additional filtering materials coming from a precoating or the like. In a preferred variant of the invention, said openings are provided with separately operable doors which open towards the inside of the tunnel. Such a closure increases the capacity? sealing of the opening in the closed state as the internal fluid presses on the doors in the closing direction and not in the opening direction. The internal hydraulic pressure then increases the strength of the seal.

Advantageously, the doors are actuated by pneumatic pistons, other systems known to the skilled person are also conceivable. Preferably, gaskets are also provided between the doors and walls of the tunnel, for example produced of fluoroelastomer.

Preferably, said gates are configured to interact with said frame so that? an opening of the door raises the frame, while a closing of the door lowers the frame. Therefore, when the door opens inwards, at the same time it raises the frame which presses on the contour of the filter medium, in particular on the filter paper, allowing it to advance in the cleaning cycle.

In this regard, the filtration system according to the invention can it also includes rollers with fresh filter paper which feed the tunnel and rollers which wind up the outgoing dirty paper, and optionally systems for removing the filter cake from the dirty paper.

A further variant of the filtration system according to the invention also comprises (e) a first tank for the dirty fluid connected via relative first ducts to the entrance/s of said tunnel/s;

(f) a second tank for the filtered fluid connected via related second pipes to the outlet(s) of said tunnel(s),

in which the second tank? equipped with a weir configured to flow fluid in a controlled manner into the first tank.

This configuration allows you to manage the plant continuously, as it will be? more forward illustrated pi? in detail, even if individual tunnels are temporarily paused for maintenance. This ? particularly important when the? plant ? integrated in a rolling mill plant. In this regard, for example, the first tank receives dirty fluids from the rolling mill, and to a lesser extent from tunnel waste and blow-down systems, while the second tank returns the filtered fluids and possibly fluids received from bypass or overflow systems of the rolling mill to the same, and possibly to hot oil recirculation systems for the spray.

The principle? been described with reference to? specific example of a rolling mill, but pu? obviously be transferred to any other type of machine which uses cooling fluids or lubricants which must be regularly cleaned and then recovered.

In an alternative variant of the plant with two tanks, the plant also comprises (g) a recirculation circuit fed by circuits for collecting waste from the tunnel(s) and/or by a blow-down circuit;

in which said first tub ? divided into a first and a second chamber which are communicating, the first chamber being fed by said weir and by a rolling mill or other machine using cooling or lubricating fluids and in turn feeding the second chamber, and the second chamber being fed by said recirculation circuit and in turn feeds through said relative first ducts said tunnel/s through said inlet/s; And

wherein said second tank feeds said rolling mill or said machine using cooling or lubricating fluids and ? fed through said related second ducts to the exit(s) of said tunnel(s).

? what? is it possible to recover more? fractions of cooling or lubricating fluids which are formed during the treatment of the fluids in the system according to the invention. Small leaks of fluid, for example the one that comes out with the closing of the doors that ?squeeze? the filter medium, are channeled with respective drains into a circuit which collects these losses or waste. In an advantageous variant of the invention, the filtration plant further comprises (h) a precoating and/or body-feed system which is? connected to said related first pipelines at the entrance(s) of said tunnel(s).

The precoating? an operation designed to deposit a layer of diatomaceous earth (or some other suitable material) on a filter medium. The filter medium can be a cloth, a wire screen, an air stone, a sintered metal or almost any permeable material, as well as the filter paper as illustrated above.

The main purpose of the pretreatment ? that of preventing blinding or clogging of the filter media and providing a clean discharge of the cake. The precoating also produces clarity superior to that provided by the filter paper alone and helps to extend the useful life of the same.

In addition to diatomaceous earth, paper fibers, perlites, activated or natural clays, carbons and metallic salts can be applied as precoating material. Commercial grades of diatomaceous earth can be obtained to provide particle retention of various grain sizes. The selection of a precoating material depends on the nature of the solids to be removed in a filtration. When choosing, the expert considers, among other things, the size of the dirt to be removed, the settling rate of the solids, the quantity? and density? solids, etc. The proportional injection of additives (also known as "body-feed") of concentrated sludge diluted with the fluid to be filtered, can be used at the start-up of the filter to provide adequate pre-treatment, the precoating, and also after the creation of a first filter layer.

A second aspect of the invention relates to a rolling mill, in particular for aluminum and its alloys, which comprises a filtration plant according to the invention.

A second aspect of the invention relates to a process for filtering fluids, in particular cooling and/or lubricating fluids, which comprises the following steps:

(I) provision of a filtration plant according to the invention;

(II) insertion of said filter medium, in particular filter paper, in at least one of said(s) one or more? tunnel;

(III) feeding of one or more? tunnels equipped with the filtering medium through said inlet(s) with dirty fluid preferably coming from said first tank, in particular from said second chamber;

(IV) collection of the filtered fluid in the lower part of the tunnel and extraction thereof through the corresponding outlet(s) and preferably conveying the filtrate to said second tank.

As mentioned above with reference to the filtration system, the power supply of the first tank can also involve recirculation circuits, and the supply of the second tank also other sources of clean fluid to also maintain a suitable level inside the tank. Involved, such as for example also in the collection of the filtrate and its future use, can be flows from and to the rolling mill or to/from machines that use cooling fluids or lubricants. Obviously part of the procedure is also the phases of replacing the card with the opening of the doors. Steps (III) and (IV) preferably occur simultaneously. In an advantageous variant of the process for filtering fluids according to the invention, a phase is introduced between phases (II) and (III)

(II-1) in which a precoating of the filter medium is carried out, in particular of the filter paper; and/or

which phase (III) ? at least partially accompanied by the introduction of a sludge of a filtering medium, in particular diatomaceous earth, into the relative tunnel on the filtering medium, in particular on the filter paper.

Especially favorite ? a variant of the invention in which in step (I) a filtration plant according to the invention is made available with the two-tank system; in which the system is managed in such a way that the fluid level is higher in the second tank; wherein in phase (IV) the filtrate is pumped from the second tank to a machine which uses said fluid to carry out cooling and/or lubrication, in particular a rolling mill, and which in phase (III) the tunnel(s) fluxes a quantity? of fluid 10% higher than that pumped from the second tank to said machine, in particular to said rolling mill.

A very advantageous variant of the process for filtering fluids according to the invention provides that at least one of the tunnels of the filtration system is isolated at the same time as steps (III) and (IV) are being carried out by disconnecting it from the supply pipes with the fluid to be filtered and from the filtrate extraction ducts and the related tunnel is maintained, cleaned or repaired. The presence of individual tunnels and what? of filtration chambers that must not be created by the compression of plates, but that are already? present in the structure of the tunnel itself and can be put into operation individually, they have the great advantage of not having to stop the entire system as in the state of the art and of avoiding having to always have a large volume of spare/saving fluid available to use during the stop so as not to interrupt production. ? it is therefore possible to carry out the maintenance, cleaning or repair of each single tunnel by equipping it, i.e. the relative pipes which connect it inside the system to sources of dirty fluids and filtrate drainages, with relative groups of valves, advantageously automatic.

The oversizing normally required to make stock fluid available to ensure proper filtration without interrupting filtration, or even the production of related facilities, is not required. more necessary.

The tunnel system concentrates the filtration area in a few tunnels, whereas the old tower system distributed the same filtration area over a large number of filtration chambers each requiring a paper roll to feed it. With the? invention the number of rollers pu? be reduced significantly, even to about a quarter.

A last aspect of the invention proposes the use of the plant and the filtration process according to the invention as an alternative also for filtering other fluids, such as for example contaminated water in the water treatment and purification sectors.

The features and advantages disclosed for one aspect of the invention may be transferred mutatis mutandis to the other aspect of the invention.

The applicability industrial ? obvious from the moment in which it becomes possible to use the filtration plant continuously, without having to stop it for maintenance, in which construction costs are reduced, in which fewer elements and materials are needed to manage the plant (reduced number of rollers, no fluid reserve volume, ?).

The said aims and advantages will be further highlighted in the description of a preferred embodiment of the invention given by way of example but not in a limiting manner.

Variants and further characteristics of the invention are the object of the dependent claims. The description of the preferred embodiment of the fluid filtration plant and process and their use according to the invention is given by way of non-limiting example with reference to the attached drawing. In particular, the number, shape, dimensions and materials of the system and of the individual components may vary, unless otherwise specified, and equivalent elements may be applied without deviating from the inventive concept.

DESCRIPTION OF FAVORITE EXAMPLES OF EXECUTION

Fig.1 shows a side view of a filtration plant according to the invention.

Fig. 2 illustrates in a detail of Fig. 1 in perspective and enlarged view two tunnels in which a part of the upper part of the tunnel ? been excised. Fig.3 illustrates in a vertical longitudinal section in perspective view one? of a tunnel with internal details.

Fig. 4 shows a horizontal longitudinal section in perspective view of the bottom of a tunnel placed in a frame.

The fig.5 illustrates a? extremity? of the tunnel in a partial section near an opening door.

Fig.6 illustrates the lower part of the tunnel with a frame for pressing the paper. Fig.7 illustrates a diagram of the fluid circuits inside the filtration system.

fig. 1 shows a side view of a filtration plant 10 according to the invention. A frame 12 has four filtration tunnel stations 14. Each tunnel 14 ? composed of a lower part 16 and an upper part 18. The upper part 18 ? fed by a pipe 20 to introduce the fluid to be filtered, while the lower part 16 is equipped with a pipe 22 for discharging the filtrate. Each end? of tunnel 14? closed by a door 24. Two inspection openings 26 and two air vents 28 are provided in each tunnel 14.

Fig. 2 illustrates in a detail of Fig. 1 in perspective and enlarged view two tunnels 14 in which a part of the upper part 18 of a tunnel is been removed to show the distribution tube 30 for the fluid to be filtered; does the tube 30 have a plurality? of holes. A series of ribs 32 reinforces the upper part 18 of the tunnel 14. Parts of a frame 34 can be seen which serves to hold still and press the paper (not shown) disposed inside the tunnel 14 on the grid 36 (fig.3).

fig. 3 illustrates in a vertical longitudinal section in perspective view an end? of a tunnel with internal details. Inside the tunnel 14 delimited by the upper part 18, the lower part 16 and the doors 24, a traditional grid 38 can be seen (drawn only partially) on which a metal mesh 36 is arranged. The card (not shown) is placed on the mesh and held still by the frame 34 in the lowered state with the doors 24 closed. Diatomaceous earth (not shown) can be deposited on the paper, which is always contained by the frame 34. At the bottom of the lower part 16 ? a channel 40 was applied which serves to collect the filtrate. Section profiles ?C? 42 reinforce the lower part 16. With the opening of the door 24, this pushes against the frame 34 and raises it, freeing the paper which can? be advanced with state-of-the-art note paper feeding and extraction systems.

Fig. 4 illustrates the bottom of a tunnel in horizontal longitudinal section in perspective view. A plurality? of ?C? 42 reinforce the lower part of the tunnel. The collection channel 40 flows into the pipe 22 to discharge the filtrate.

fig. 5 illustrates a? extremity? of the tunnel 14 in a partial section near an opening door 24. On a support 44 in the vicinity of the door 24 ? a series of pneumatic pistons 46 is applied to actuate the opening and closing of the door 24 which, when opened, strikes against the frame 34 which rises to release the paper (not shown).

fig. 6 illustrates the underside 16 of the tunnel with the frame 34 extending along the inner perimeter of the underside 16 of the tunnel. At the bottom of the lower part of the tunnel, the filtered collection channel 40 can be seen.

fig. 7 shows a diagram of the fluid circuits inside the filtration system in which four units can be seen main: the unit? filtration A real with a series of four tunnels 14, the unit? of tanks B for the fluid to be filtered and for the filtrate; the unit? management of the individual circuits C, in the form of a skid with pumps, valves, pipes, etc.; and the unit? ?precoating and body-feed? Q. The underside of each tunnel 14 ? equipped with a discharge circuit 22 for removing the filtrate, while its upper part ? equipped with a supply circuit 20 which supplies the tunnel 14 with the dirty fluid. Each tunnel 14 has a discharge circuit 22 and a supply circuit 20 which? which can be managed separately in order to be able to disconnect the tunnel from the filtrate and fluid ducts to be filtered. In this regard, groups of valves 71 and 72 allow to connect/disconnect respectively the lines 20.1, 20.2, 20.3, 20.4 and 22.1, 22.2, 22.3 and 22.4 which branch off respectively from the pipes 20.0 and 22.0, what? allowing you to exclude one or more? of tunnels 14 for repair, cleaning or maintenance work without having to stop the whole system, as happens in the state of the art. All tunnels 14 are provided with vents 28. For each tunnel 14 ? associated with a circuit 48 which collects the rejects coming out of the entrance and/or entrance of the tunnel, flowing them into the recirculation tank 50 which is also fed by the circuit 68 which collects the sediments formed in the valves of the filtrate circuit 22.0, ie? the blow down.

The recirculation tank 50 which then recirculates waste and liquids from the blow-down ? in communication with the tank 52 for the dirty fluid which is filled from various sources, and precisely by cooling/lubricating fluids coming 57 from a rolling mill 55, which is the main source, from a general fill 56 and a weir 53, fed from the clean fluid tank 54, what will it look like? illustrated more after you. The clean fluid tank 54 also receives fluids from the bypass and overflow lines 62 of the rolling mill 55 and obviously from the line 22.0 which conveys the filtrate collected in the various tunnels 14. The tank 54 itself? equipped with a connection to the mill 55 for transferring the filtered and therefore cleaned fluid to the latter and a connection 64 to a recirculation system for hot spray systems. All tanks also have 60 drainage devices.

The dirty fluid conveying lines 20.1 to 20.4 can be supplied by compressed air 70 for their cleaning. Every single dirty fluid line from 20.1 to 20.4 ? feedable before the pump-valves system 72 through a relative line 82 from the precoating and bodyfeed system D which ? composed of a tank 74 with an agitator 76 and a pump 80 fed by compressed air 78 and fed with clean oil 76 in which a sludge of oil and diatomaceous earth is prepared.

The unit tanks B for fluids ? divided into two parts, the dirty side (tank with chambers 50 and 52) and the clean side (tank 54). The clean side has a higher fluid level than the other and c?? a weir 53 from the clean fluid towards the dirt, in fact during production the tank 54 ? always full, while those of dirt 52, 50 to about 30%. The filter system A fluxes a quantity? of liquid greater than 10% to what is pumped from the tank of the clean 54 to the rolling mill 55, the excess falls through the weir 53 into the tank of the dirt 52. As already? illustrated, the dirty side ? in turn divided into two, or rather a small part, the room 50? dedicated to manage the blow-down and rejects and their recirculation, while the chamber 52 collects the fluids from the mill 55. These two chambers 50 and 52 which make up the dirty side are in communication, in which the partial division serves to maintain the part of fluid more? dirty a little? more segregated. In the blow-down phase, compressed air is blown into the filters and all the fluid is discharged into the recirculation section 50.

In the precoating phase, a minimum quantity of diluted earth is sent to the pump, which recirculates between the filters and the recirculation tank 50, which is deposited inside the filter; at the end of the precoating phase we continue to send diatomaceous earth diluted by the unit? body-feed D to the filters, that is? to the tunnel 14, but in this phase it begins gi? to filter, the fluid is then taken from the dirt tank 50 and sent through the tunnels 14 to the clean tank 54. The body-feed ? connected to the suction of the recirculation pumps.

The division into dirty and clean of the tanks has an important aspect from the point of view of the volumes; in fact, the volume contained in the clean side must be sufficient to allow the filter/tunnel cleaning cycle.

As regards the old filtration system known in the art, it was necessary to completely suspend the filtration and an important volume of clean spare fluid was necessary in order not to stop the production, now instead three quarters of the capacity? filter remain, for example if a tunnel is stopped for maintenance, and the clean fluid level drops much more? slowly and this makes it possible to considerably reduce the total volume of fluid required to manage the system.

Claims (12)

1) Filtration system (10) for fluids, in particular cooling and/or lubricant fluids, comprising: (a) one or more tunnel (14) each divided into an upper part (18) and a lower part (16), equipped with at least one entrance (20), in particular in the upper part (18), and at least one exit (22), in particular in the lower part (16), to respectively introduce the fluid to be filtered and to extract the filtered fluid, in which each tunnel (14) has on each end? a hermetically closable opening for the inlet and outlet of a filter medium, in particular filter paper; (b) a frame (12) for housing said/s one or more? tunnels (14); (c) a permeable support (36, 38) in the lower part (16) for supporting the filter medium, in particular the filter paper; (d) a group of valves (71, 72) for each tunnel (14) which can be configured to isolate the tunnel (14) from fluid flows entering and/or leaving it. 2) Filtration plant (10) according to claim 1 characterized in that said/these one or more? Tunnels (14) are/are made of sheet metal, preferably reinforced by ribs and/or profiles (32, 42). 3) Filtration plant (10) according to claim 1 or 2 characterized in that each tunnel (14) comprises a frame (34), preferably metallic, placed in a way that can be lifted and lowered above said support (36, 38). 4) Filtration plant (10) according to any one of the preceding claims, characterized in that said openings are provided with separately operable doors (24) which open towards the inside of the tunnel (14). 5) Filtration plant according to claim 4 characterized by the fact that said doors (24) are configured so as to interact with said frame (34) so that? an opening of the door (24) raises the frame (34), while a closing of the door (24) lowers the frame (34). 6) Filtration plant (10) according to any one of the preceding claims characterized in that it also comprises (e) a first tank (50, 52) for the dirty cooling fluid connected via relative first pipes (20.0.20.1, 20.2, 20.3, 20.4) to the entrance/s (20) of said tunnel/s (14) ; (f) a second tank (54) for the filtered cooling fluid connected via relative second pipes (22.0, 22.1, 22.2, 22.3, 22.4) to the outlet(s) (22) of said tunnel(s) (14), in which the second tank (54) ? equipped with a weir (53) configured to flow fluid in a controlled manner into the first tank (52). 7) Filtration plant (10) according to claim 6 characterized in that it also comprises (g) a recirculation circuit fed by reject collection circuits (48) from the tunnel(s) (14) and/or by a blow-down circuit (68); in which said first tub ? divided into a first (52) and a second chamber (50) which are communicating, the first chamber (52) being fed by said weir (53) and by a rolling mill (55) or other machine using cooling fluids and/or lubricants and in turn feeding the second chamber (50), and the second chamber (50) being fed by said recirculation circuit (48, 68) and feeding in turn through said relative first ducts (20.0, 20.1, 20.2, 20.3, 20.4) said tunnel(s) (14) through said entrance(s) (20); And wherein said second tank (54) feeds said rolling mill (55) or said machine using cooling and/or lubricant fluids and ? fed through said related second ducts (22.0, 22.1, 22.2, 22.3, 22.4) to the outlet(s) (22) of said tunnel(s) (14). 8) Filtration plant (10) according to any one of the preceding claims characterized in that it also comprises (h) a precoating and/or body-feed system (D) which ? connected to said related first pipelines (20.0, 20.1, 20.2, 20.3, 20.4) to the entrance/s (20) of said tunnel/s (14). 9) Process for filtering fluids, in particular cooling fluids and/or lubricants, comprising the following steps: (I) provision of a filtration plant (10) according to any one of the preceding claims; (II) insertion of said filter medium, in particular filter paper, in at least one of said(s) one or more? tunnels (10); (III) feeding of one or more? tunnels (14) equipped with filter medium, in particular filter paper, through said inlet/s (20) with dirty fluid preferably coming from said first tank (50, 52), in particular from said second chamber (50); (IV) collection of the filtered fluid in the lower part (16) of the tunnel (14) and extraction of the same through the corresponding outlet(s) (22) and preferably conveying the filtrate to said second tank (54). 10) Process for filtering fluids according to claim 9 characterized in that a phase is introduced between phases (II) and (III) (II-1) in which a precoating of the filter medium is carried out, in particular of the filter paper; and/or which phase (III) ? at least partially accompanied by the introduction of a sludge of a filtering media, in particular diatomaceous earth into the relative tunnel (14) on the filtering medium, in particular on the filter paper. 11) Process for filtering fluids according to claim 9 or 10 characterized in that in phase (I) a filtration plant (10) according to any one of claims from 6 to 8 is provided; that the plant is managed in such a way that the fluid level is higher in the second tank (54) than the level in the first tank (50, 52); that in phase (IV) finally the filtrate is pumped from the second tank (54) to a machine which uses said fluid to effect cooling and/or lubrication, in particular a rolling mill (55), and that in phase (III) the/ the tunnels (14) flux / not a quantity? of fluid 10% higher than what is pumped from the second tank (54) to said machine, in particular to said rolling mill (55). 12) Process for filtering fluids according to any one of claims from 9 to 11 characterized in that simultaneously with the execution of phases (III) and (IV) at least one of the tunnels (14) of the filtration system (10) is isolated by disconnecting it from the supply pipes with fluid to be filtered (20.0, 20.1, 20.2, 20.3, 20.4) and filtrate extraction pipes (22.0, 22.1, 22.2, 22.3, 22.4) and maintenance, cleaning or repairs are carried out.