ITVR20130135A1 - EQUIPMENT FOR FILTRATION / CONCENTRATION OF LIQUIDS, PARTICULARLY FOOD LIQUIDS, WITH SOLID SUBSTANCES IN SUSPENSION - Google Patents

Description

EQUIPMENT FOR FILTRATION / CONCENTRATION OF LIQUIDS, ESPECIALLY FOOD LIQUIDS, WITH SUSPENDED SOLID SUBSTANCES

DESCRIPTION

The present invention relates to an apparatus for filtering / concentrating liquids, particularly food liquids, with solid substances in suspension.

As is known, in the food sector, it is usual to filter or concentrate the food liquids being processed.

In the food industry and, more particularly, in the wine industry, the separation of the main process fluid from the particles deriving from the processing of the raw material constitutes in fact an extremely critical processing phase.

For example, in the wine industry, the sediments of musts or wines, obtained through enzymatic processes or clarification with adjuvants, still have a high content of fermentable must or wine.

The extraction from the sediments of the fraction of fermentable must or wine is very difficult, as the high presence of suspended solids in a high density liquid does not allow separation with centrifugal means, but only with vacuum filters and in the presence of large quantities of filter aid, such as perlite.

The use ratios of perlite vary from about 1-1.5 kg per 100 kg of must or wine sediments to be filtered.

This technique, although dated, is still used today also in other food sectors, for example in the concentration of fruit purees or yeast from bioreactors, as well as in other industrial sectors for the exhaustion of exhausted sediments or not, in processes of separation.

Despite being widely used, vacuum filtration has numerous drawbacks.

A first drawback is to expose the product to be filtered, the filtrate and the particles separated from the product to be filtered to a very high oxygenation, due to their continuous contact with the atmosphere.

Vacuum filtration therefore involves problems of uncontrolled oxidation of all the polyphenolic components, loss of alcohol in the atmosphere and a general deterioration of the organoleptic characteristics of the product, also due to its consistent enrichment of exogenous substances, deriving from the use of adjuvants of filtration, consisting of calcareous stone dust.

Not even the alternative use of diatomaceous adjuvants, i.e. of fossil origin, allows to obtain better results.

Tangential filtration devices are also known, based on the use of membranes, which however cannot work with liquids having a high content of suspended solids, as the commonly used circulation pumps are not able to guarantee a speed of passage of the liquid, on the walls of the membranes, such as to allow to keep the membranes clean, removing by friction the deposit of solid substances that tends to form on the walls of the membranes, called, in jargon, polarization gel.

It should be further highlighted that in these filtration devices, due to the high speed that must be imparted to the fluid to be filtered in an attempt to obtain a removal of the polarization gel, the pumps used operate a continuous recirculation of the fluid to be filtered, with consequent consumption high energy.

Another type of filters currently used has internal cavity membranes, ie membranes configured with hollow fiber, in which filtration takes place from the inside of the membrane cavity towards the outside.

A limitation to the use of membranes with internal cavities is due to the lumen available for the passage of the fluid to be treated, the size of which considerably affects the quantity of admissible suspended solids. In fact, with this type of membranes, clogging occurs not so much in the filter septum, but rather in their internal cavity, through which the fluid to be treated is made to flow. To apply hollow-shaped membranes, it is therefore necessary to use larger passage sections, passing from the typical sections of 0.9-1.2 mm of internal diameter to sections of 20-30 mm of internal diameter. The energy input for moving high-flow fluids on sections of this type is very high, which makes systems with internal cavity membranes not competitive with respect to vacuum filtration and therefore not convenient.

The main aim of the present invention is to provide a solution to the problems of the known art, realizing an apparatus for the filtration / concentration of liquids, particularly food liquids, with solid substances in suspension which allows to treat, effectively and without incurring unwanted clogging , liquids with a high content of solid substances in suspension, while avoiding altering their qualitative and organoleptic characteristics.

Within this aim, an object of the invention is to provide an apparatus for the filtration / concentration of liquids, particularly food liquids, with solid substances in suspension which has extremely limited operating and management costs.

A further object of the invention is to provide an apparatus for the filtration / concentration of liquids, particularly food liquids, with solid substances in suspension, which does not use filtration aids, with consequent cost savings and greater respect for the environment.

Another object of the present invention is to provide an apparatus for the filtration / concentration of liquids, particularly food liquids, with solid substances in suspension, which due to its manufacturing characteristics is able to offer the widest guarantees of safety and reliability in its operation.

Another object of the present invention is to provide an apparatus for the filtration / concentration of liquids, particularly food liquids, with solid substances in suspension, which can be validly used both for obtaining filtered products, i.e. deprived of particles , both for the concentration of the particles, by removing the liquid fraction.

A further object of the invention is to provide an apparatus for the filtration / concentration of liquids, particularly food liquids, with solid substances in suspension, which allows a high energy saving with respect to the known art, avoiding to move the product to be filtered with continuous recirculations.

Not least object of the present invention is to provide an apparatus for the filtration / concentration of liquids, particularly food liquids, with solid substances in suspension, which can be easily obtained by means of materials and elements that are easily available on the market so as to be competitive also from a purely economic point of view.

This aim, as well as these and other objects which will appear better below, are achieved by an apparatus for the filtration / concentration of liquids, particularly food liquids, with solid substances in suspension, according to the invention, as defined in claim 1.

Further characteristics and advantages of the invention will become clearer from the description of a preferred but not exclusive embodiment of the apparatus for the filtration / concentration of liquids, particularly food liquids, with solid substances in suspension, according to the invention, illustrated by way of example and non-limiting, in the accompanying drawings in which:

Figure 1 is a schematic and longitudinal section view of the apparatus according to the invention.

With reference to the aforementioned figures, the apparatus for the filtration / concentration of liquids, particularly food liquids, with solid substances in suspension, according to the invention, indicated as a whole with the reference number 1, comprises a casing 2, defining a containment chamber 2a intended to contain a liquid to be treated with solid substances in suspension, even in high concentration, such as, for example, a sedimented must to be filtered, a fruit puree to be concentrated, wine sediments or waste water to be purified.

Inside the envelope 2 is housed a plurality of hollow fibers 3 in a porous membrane, which are intended to be immersed, at least partially, in the liquid to be treated and can be connected, with their internal cavity, to suction means 4, which have the function of sucking, from the internal cavity of the hollow fibers 3, the liquid filtered through the porous membrane of the hollow fibers 3 themselves.

Advantageously, the porous membrane which constructs the wall of the hollow fibers 3, in addition to being suitable for contact with the liquid to be treated, may be of the type suitable for microfiltration or of the type suitable for ultrafiltration, according to requirements.

Conveniently, according to the illustrated embodiment, the envelope 2 has a substantially cylindrical conformation with a substantially vertical axis, while the hollow fibers 3 are arranged according to a bundle oriented substantially parallel to the axis of the envelope 2.

More in detail, the hollow fibers 3 advantageously have a closed end 3a, facing the bottom of the casing 2 and freely immersed in the liquid to be treated, and an opposite open end 3b, which is in communication with the suction means 4 .

Conveniently, in the lower part of the casing 2 and, more preferably, below the hollow fibers 3, means 5 are provided for blowing in a gas under pressure, preferably inert towards the liquid to be treated, such as, for example, nitrogen or other gas, or gas mixture, inert or enriched with antioxidant gases, such as sulfur dioxide. This gas under pressure, in its ascent towards the upper part of the envelope 2, is intended to lick the external surface of the hollow fibers 3, in order to clean it, removing any sediments adhering to the surface of the hollow fibers 3.

In particular, during the rising of the gas bubbles delivered by the insufflation means 5, the hollow fibers 3, being free to move in the liquid to be treated at their closed end 3a, perform constant movements inside the liquid to be treated which they generate friction with the solid particles contained in the liquid to be treated, in order to keep the filtering surface of the hollow fibers themselves clean. For example, the insufflation means 5 can consist of a shower head 5a provided with a plurality of dispensing nozzles, connected by means of a supply duct 6 to an external source of the gas under pressure.

Advantageously, in the upper part of the casing 2 there is defined a port 7 for discharging the undissolved gas delivered by the insufflation means 5, to allow it to escape from the casing 2.

The exhaust port 7 can be in communication with the external environment, so as to allow the gas to be discharged into the environment, or, possibly, it can also be connected to the insufflation means 5, suitably by means of the interposition of a motorized blower 6a , to allow the reuse of the gas escaping from the casing 2. Conveniently, in the upper part of the casing 2, preferably above the hollow fibers 3, there is an inlet fitting 8 for the liquid to be treated, consisting, for example, from an inlet duct 8a passing through the external lateral plating of the casing 2, while, in correspondence with the bottom of the casing 2, an outlet fitting 9 is defined, through which the solid substances can be discharged and separated from the liquid to be treated.

Always referring to the embodiment shown, the suction means 4 conveniently comprise a withdrawal circuit which has at least one collector duct 10, which communicates with the internal cavity of the hollow fibers 3 and is connected to a collection vessel 11 , inside which the filtered liquid reaches through the porous membrane of the hollow fibers 3, due to the action of return means connected to said collection vessel 11.

Preferably, but not necessarily, the collector duct 10 is fixed to a head 12 which supports the hollow fibers 3 and which can be, for example, constituted by a resin disc, in which the open end 3b of the fibers is embedded. cavity 3, which is connected to the collector duct 10 by means of an intermediate conveying chamber. The collection vessel 11 is advantageously connected to vacuum creation means by means of a vacuum line 13 suitably connected to the upper part of the collection vessel 11.

By means of the interposition of a sampling pump 14, the collection vessel 11 is also connected, preferably in correspondence with its lower part, to an evacuation duct 15 for the filtered liquid.

It should be noted that, conveniently, the sampling pump 14 is sized so as to be able to work even without the joint action of the vacuum creation means.

Advantageously, introduction means are also provided which allow the filtered liquid to be introduced in countercurrent into the internal cavity of the hollow fibers 3, in order to wash and regenerate the porous membrane of the hollow fibers 3.

In particular, such inlet means can, for example, comprise a conduit 16 for conveying a compressed gas, such as, for example, nitrogen or other gases compatible with the product to be treated, which can be connected, by means of suitable valve means 16a, with the collection vessel 11, so as to be able to create, inside the collection vessel 11, a pressure such as to make the filtered liquid flow from the collection vessel 11 towards the internal cavity of the hollow fibers 3 through the collector duct 10.

Conveniently, the aforementioned inlet means may also comprise a connecting duct 17, connected, at the inlet, to the delivery port of said sampling pump 14 and communicating, at the outlet, with the collector duct 10, so as to allow the delivery , by means of the pump 14, of the liquid filtered from the collection vessel 11 to the internal cavity of the hollow fibers 3.

The operation of the apparatus according to the invention is as follows.

Through the inlet fitting 8, the liquid to be treated enters the containment chamber 2a defined by the casing 2.

Once the containment chamber 2 has been filled to cover the hollow fibers 3, the suction means 4 are activated, so as to generate a flow of liquid, through the porous membrane of the hollow fibers 3, from the containment chamber 2a towards the cavity internal cavity of the hollow fibers 3, and the conveyance of the filtered liquid in the internal cavity of the hollow fibers 3 towards the collection vessel 11.

More specifically, the activation of the suction means 4 is obtained by putting the collection vessel 11 in communication, through the vacuum line 13, with the means for creating the vacuum, so as to recall, inside the collection vessel 11 and through the collecting duct 10, the filtered liquid which has reached the internal cavity of the hollow fibers 3.

By activating the sampling pump 14, the filtered liquid can then be conveyed from the collection vessel 11 to the evacuation duct 15.

Eventually, the suction action of the filtered liquid in the collection vessel 11 can also be exercised by the sampling pump 14 alone. During the activation of the suction means 4, the level of the liquid to be treated inside the casing 2 may be kept constant by a continuous flow of liquid to be treated into the containment chamber 2a from the inlet fitting 8.

Following the activation of the suction means 4, the solid substances suspended in the liquid to be treated, in progressive concentration inside the containment chamber 2a, tend to migrate by gravity towards the bottom of the casing 2 and to remain in the lower part of the same. , up to their withdrawal, which takes place through the exit connection 9, when the concentration reached by them will be considered adequate.

Simultaneously with the activation of the suction means 4, the insufflation means 5 can also be activated, which introduce into the liquid to be treated the gas under pressure which comes from the supply duct 6 and which can expand directly inside the liquid to be treated. to deal. In particular, gas bubbles are continuously released from the shower head 5a which rise upwards, touching the hollow fibers 3, so as to cause cleaning of any solid substances adhering to their external surface.

The gas delivered by the insufflation means 5 that does not dissolve in the liquid to be treated will collect in the upper part of the casing 2 and will be evacuated from the containment chamber 2a through the discharge port 7, for its immediate reuse by the means of insufflation 5 or for its direct discharge into the environment.

The means for introducing the filtered liquid in countercurrent into the internal cavity of the hollow fibers 3 can be activated periodically, in order to regenerate the porous membranes that make up the hollow fibers 3.

For this purpose, once the communication between the collection vessel 11 and the vacuum creation means has been interrupted by closing a suitable interception valve 13a, it is possible to put the conveying duct 16 in communication with the collection vessel 11, so as to introduce compressed gas into the collection vessel 11, to thus obtain an inflow of filtered liquid from the conveying duct 10 towards the internal cavity of the hollow fibers 3 and from the latter towards the containment chamber 2a, with a crossing in counter-current, with respect to the direction of filtration, of the porous membrane of the hollow fibers 3 by the filtered liquid.

The same counter-current flow of the liquid filtered in the hollow fibers 3 can also be obtained by activating the sampling pump 14 and putting its delivery port in communication with the collector duct 10 through the connecting duct 17.

The regeneration operations of the porous membrane of the hollow fibers 3 can be carried out according to various parameters, such as, by way of example, the decay of the filtrate withdrawal flow rate or the increase of the transmembrane pressure.

In practice it has been found that the invention is capable of fully achieving the intended aim and objects.

In particular, it is emphasized that the apparatus according to the invention provides for the use of hollow fibers that perform filtration with a flow that proceeds from the outside towards the inside of the hollow fibers themselves, thus avoiding having particle contaminants in sections very small passage. This allows the equipment to operate even in the presence of liquids to be treated having a very high concentration of solid substances suspended inside them.

It should also be pointed out that the apparatus according to the invention, working inside a closed structure, makes it possible to avoid contact of the liquid to be treated, of the filtered liquid and also of the concentrate obtained with the atmosphere and therefore with oxygen. .

Furthermore, the porous membranes of the hollow fibers do not involve any transfer of unwanted substances and do not require an adjuvant, fully respecting the original organoleptic characteristics of the liquid to be treated.

Finally, it should be pointed out that the energy consumption of the apparatus according to the invention is extremely low, as it is limited to the activation of the vacuum creation means and to the occasional operation of the sampling pump for evacuation of the filtered liquid. More particularly, it should be pointed out that the apparatus according to the invention allows a high energy saving with respect to the known technique since it does not move the product to be filtered with continuous recirculation.

All the characteristics of the invention, indicated above as advantageous, convenient or the like, can also be missing or be replaced by equivalents. The individual characteristics set forth with reference to general teachings or particular embodiments can all be present in other embodiments or substitute features in these embodiments.

The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept.

In practice, the materials used, as well as the dimensions and shapes, may be any according to requirements.

Furthermore, all the details can be replaced by other technically equivalent elements.

Claims (13)

CLAIMS 1. Equipment for the filtration / concentration of liquids, particularly food liquids, with solid substances in suspension characterized by the fact of comprising a casing (2) suitable for containing a liquid to be treated with solid substances in suspension and housing a plurality of hollow fibers (3) in a porous membrane, immersed, at least partially, in said liquid to be treated and connectable, with their own internal cavity, to suction means (4) of the liquid filtered through the porous membrane of said hollow fibers (3). 2. Apparatus according to claim 1, characterized in that said casing (2) has a substantially cylindrical conformation with a substantially vertical axis, said hollow fibers (3) being arranged according to a bundle oriented substantially parallel to the axis of said casing (2) . 3. Apparatus according to one or more of the preceding claims, characterized in that said hollow fibers (3) have a closed end (3a), facing the bottom of said casing (2) and freely immersed in said liquid to be treated, and a opposite open end (3b), communicating with said suction means (4). 4. Apparatus according to one or more of the preceding claims, characterized in that it comprises, in the lower part of said casing (2), means for insufflation (5) of a gas under pressure, intended to lap the external surface of said hollow fibers ( 3). 5. Apparatus according to one or more of the preceding claims, characterized in that said casing (2) has, in its upper part, an outlet (7) for the undissolved gas delivered by said insufflation means (5). 6. Apparatus according to one or more of the preceding claims, characterized in that it comprises, in the upper part of said casing (2), an inlet fitting (8) for said liquid to be treated, being provided at the bottom of said casing (2), an outlet fitting (9) for the solid substances separated from said liquid to be treated. 7. Apparatus according to one or more of the preceding claims, characterized in that said suction means (4) comprise a withdrawal circuit having at least one collector duct (10), communicating with the internal cavity of said hollow fibers (3) and leading to a collection vessel (11) connected to means for recalling the filtered liquid. 8. Apparatus according to one or more of the preceding claims, characterized in that said collection vessel (11) is connected, through the interposition of a sampling pump (14), to an evacuation duct (15) of the filtered liquid . 9. Apparatus according to one or more of the preceding claims, characterized in that said collection vessel (11) is connected to vacuum creation means. 10. Apparatus according to one or more of the preceding claims, characterized in that it comprises means for introducing the filtered liquid in counter-current into said hollow fibers (3), for washing the porous membrane of said hollow fibers (3). 11. Apparatus according to one or more of the preceding claims, characterized in that said inlet means comprise a conduit (16) for conveying compressed gas inside said collection vessel (11). 12. Apparatus according to one or more of the preceding claims, characterized in that said inlet means comprise a connecting duct (17), connected, at the inlet, to the delivery port of said sampling pump (14) and communicating, at the outlet , with said collector duct (10). 13. Apparatus according to one or more of the preceding claims, characterized in that said discharge port (7) is connected, by means of the interposition of a motorized blower (6a), to said insufflation means (5), for the recovery forced of said undissolved gas.