"PROCESS AND DEVICE FOR CORK MATERIAL EXPANSION BY SATURATED AND/OR OVERHEATED STEAM"

FIELD OF THE INVENTION

This invention is related to a process and device allowing the volume expansion of cork without use of foreign substances with respect to cork. More specifically, it is related to a process which consists in subjecting cork to saturated and/or overheated steam resulting in an increased material volume, therefore in a higher yield, and to a device to perform such process.

BACKGROUND OF THE INVENTION

Cork is a natural product having high quality and wide industrial applicability that extends from wine to construction industry. There is a high demand for cork both as a raw material and due to its unique characteristics, but being a natural resource it is limited.

Water or steam are already used in several cork or cork derived processing stages. Most of cork extracted from cork-oak is subjected to a boiling process with water at about 90 ⁰ C for about 1 hour. This process is well known in the cork industry and is used to flatten cork planks. This operation is crucial for flattening planks and imparts moisture which is necessary for stopper broaching operations.

Water, in the form of overheated steam, is also used for production of black agglomerate, for which granulated cork without pre-treatment (boiling) is used. The overheated steam may reach higher temperatures than 340 ⁰ C. In this process, cork granules have a considerable volume expansion, the adhesion between granules takes place, so as to avoid the need of synthetic glue. However, this process causes a strong cork degradation, which considerably decreases its commercial value. This process is

described in British Patent N ⁰ 16935. For the production of black agglomerate, cell expansion is obtained together with a thickness reduction of its cell wall and with an important chemical modification (see Materials Science and Engineering A. H. Pereira and E. Ferreira, 1989, 111 , pages 217-225). These situations also contribute to a reduction on cork quality, and consequently on its commercial value. Additionally, the black agglomerate production process imparts a dark colour (thus the designation of "black agglomerate") to planks so produced that significantly impair the aesthetic aspects.

Patent application WO 014436 Al discloses a process wherein steam is used in cork treatment. This process is intended for removing off-flavours from cork using relatively low temperatures in the range of 100 to 125 ⁰ C.

Patent application US 2588418 A also relates to the use of steam for treating cork. This process is used to disaggregate granulated cork which was previously packed for transport purposes.

SUMMARY OF THE INVENTION

The process and device of the present invention overcome the drawbacks of prior art processes such as the black agglomerate production. They are further compliant with supporting processes to the manufacturing processes, such as, for example, cork plank boiling, off-flavour withdrawing from cork material or disaggregation of previously packed granulated cork, thereby assuring an expansion product (resulting product) having higher volume, which is lighter and more resistant than the starting cork material (or raw material).

The expansion process of the invention may be performed in continuous or batch mode and has three stages. The first stage comprises feeding of material, followed by a second stage of expansion and finally by the third discharge stage or, preferably, cooling and discharge stage.

In relation to first stage or feeding stage, this comprises a cork material delivery into an expansion zone. In a continuous process, the feeding stage is designed to supply an expansion zone and to confine steam in the expansion zone. In a batch process, the feeding stage is designed to supply the expansion zone and recover the steam which remains in that expansion zone.

With respect to the second stage or expansion stage, this comprises a saturated and/or overheated steam delivery to an expansion zone and containment of saturated and/or overheated steam in the expansion zone.

In the expansion zone, all the cork material to be processed should be subjected to said saturated and/or overheated steam at a temperature in the range of about

150 - 340 ⁰ C, preferably in the range of about 280 - 310 ⁰ C and an overpressure in the range of about 0.1 to 0.5 bar for a period in the range of about 30 seconds to 15 minutes, preferably in the range of about 30 seconds to 5 minutes.

In relation to the third stage or discharge stage, this comprises the discharge or, preferably, cooling and discharge, of product resulting from second stage of expansion process of the invention. This stage comprises the containment of steam in the expansion zone and the cooling and collection of the cork expanded in the expansion zone.

The present invention is further related to an expansion device comprising a feeding assembly, a discharge assembly and an expansion assembly or chamber between the feeding and discharge assemblies, wherein said feeding assembly comprises a sealing member, a cork material admission and a cork material conveying member; said expansion assembly comprises an housing and a conveying and contact inner mechanism, and said discharge assembly comprises a sealing member and a collection and conveying member, wherein

said sealing member of feeding assembly is arranged above the admission, sealingly connected to inlet opening of said cork material admission, in first end of conveying member and upstream of the feeding opening of expansion assembly UE, designed for containment of saturated and/or overheated steam in the feeding and expansion assemblies;

said cork material admission of feeding assembly is arranged in a first end of conveying member, connected to sealing member and arranged below latter, used to receive cork material and send it to the conveying member, and comprising a size and shape suitable to the amount of cork material to be supplied to the expansion assembly;

said conveying member of feeding assembly directs cork material to a feeding opening of the expansion assembly;

said housing of expansion assembly is hollow, comprising,

at least, one feeding opening arranged in a first end of the housing, on top of the expansion assembly housing, communicating com the conveying member of feeding assembly, designed to enable cork material delivery into the expansion assembly housing so as to supply cork material to conveying and contact inner mechanism of the expansion assembly,

at least, four inlet openings of saturated and/or overheated steam arranged in a lower portion of housing of the expansion assembly and substantially uniformly located in the wall on either side of said housing,

at least, two saturated and/or overheated steam outlet openings arranged and located along the top of housing of the expansion assembly, for steam flowing, the outlet openings acting as exhaust valves or converging to, at least, one exhaust valve outside of the expansion chamber housing,

at least, one thermofluid inlet opening arranged in the transverse face of said first end of housing of the expansion assembly or in any other suitable location of housing, for admission of a preceding heating fluid of the wall of the expansion assembly housing,

at least, one thermofluid outlet opening arranged in the transverse face of said first end of housing of the expansion assembly or in any other suitable location of housing, for flowing of said preceding heating fluid of wall of the expansion assembly housing and

at least, one discharge opening arranged in the second end of housing, opposite to first end of the feeding opening, in the lower portion of housing, connected to collection and conveying member of the discharge assembly and designed to enable delivery of the expanded cork material into discharge assembly;

said conveying and contact inner mechanism of the expansion assembly is located within the housing of the expansion assembly, while assures conveying and a substantially uniform contact of cork material with saturated and/or overheated steam from said feeding inlet of housing to the discharge assembly;

said sealing member of discharge assembly is arranged, in a first end of the collection and conveying member, in the discharge opening of chamber housing, and is designed for containment of saturated and/or overheated steam in the expansion and feeding assemblies;

said collection and conveying member of discharge assembly collects the expanded cork material of discharge opening of the expansion chamber and convey it out of the expansion device and

said conveying members of feeding, expansion and discharge assemblies have synchronized conveying speed with each other.

Each of said conveying member of feeding assembly, conveying and contact member of expansion assembly and collection and conveying member of discharge assembly comprise a conveying means selected from the group consisting of worm screw, conveyor belt made of steel or any other suitable material, fluidization belt, and pneumatic conveyor.

Each of said sealing member of feeding assembly and sealing member of discharge assembly comprise a sealing means selected from the group consisting of feeding "hatchway", manual or electro-pneumatic sealing door, and an antechamber having two alternate entry /exit access points.

If cork planks are used, said feeding and discharge assemblies comprise two sealing slides having an alternative motion for admission and delivery of the cork planks.

In one embodiment, said sealing member of feeding assembly is a sealing hatchway; said admission of feeding assembly is a admission hopper; said conveying member of feeding assembly is a um worm screw; said housing of expansion assembly comprises:

a cork material inlet,

two overheated steam inlets arranged outside and laterally, one on either side of chamber housing, each splits into two overheated steam inlet openings arranged on either side of chamber housing,

four steam outlets located along the top of the chamber housing converging to a single steam exhaust valve arranged outside and above the chamber housing,

one thermofluid inlet,

one thermofluid outlet and

one expanded material outlet;

said conveying and contact inner mechanism of expansion chamber is a worm screw; said sealing member of discharge assembly is a sealing hatchway; said collection and conveying member of discharge assembly is a worm screw and the expansion device is supplied with grounded cork.

In another embodiment of the invention, at least two expansion devices connected in parallel to each other form an expansion apparatus.

The expansion process and device of the invention use any cork material selected from the group comprising falca cork, virgin or reproduction cork, cork planks, cork residues (from the production of stoppers or cork plank transformation), grounded, granulated and powdered cork.

The following detailed description of the invention is made with reference to embodiments and to the accompanying Figures.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 and 2 schematically show cork cells in radial direction and in axial/tangential direction, respectively,

Fig. 3 shows cork pictures obtained from scanning electron microscopy in radial and non-radial directions, illustrating cork morphology before and after an expansion process.

Fig. 4 schematically shows an exploded view of the expansion device of the present invention.

Fig. 5 schematically shows a top view of an expansion assembly of the invention.

Fig. 6 schematically shows a side view of an expansion assembly of the invention.

Fig. 7 schematically shows a front view of an expansion assembly of the invention.

Fig. 8 schematically shows a preferred feeding assembly of the invention.

Fig. 9 schematically shows a side view of a preferred expansion assembly of the invention.

Fig. 10 schematically shows a top view of a preferred expansion assembly of the invention.

Fig. 11 schematically shows a front view of a preferred expansion assembly of the invention.

Fig. 12 schematically shows a preferred discharge assembly of the invention.

Fig. 13 schematically shows a feeding assembly of device of the invention for the particular condition of cork plank feeding.

Fig. 14 schematically shows a discharge assembly of device of the invention for the particular condition of cork plank discharge.

Fig. 15 is a schematic front view of an apparatus having two expansion chambers of the invention connected in parallel to each other.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is related to a process and device allowing volume expansion of cork without use of foreign substances with respect to cork. Subsequently, the resulting cork may be subjected to usual prior art processes of the cork industry.

Any cork material may be subjected to the expansion process and device of the invention, regardless its shape, origin quality or pre- treatments. Falca cork, virgin or reproduction cork, cork planks, cork residues (from the production of stoppers or cork plank transformation), grounded, granulated, powdered cork and the like, or any of preceding in a boiled condition, may be used.

To better understand the modifications in the cork material after subjection to the process of the present invention, it is hereinafter described some intrinsic features of cork.

In a microscopic level, cork may be described as an homogeneous tissue with thin cells without space between them and arranged in an alveolar structure similar to a honey-comb. Cork cells exhibit a wide range of different shapes as they are seen in the radial direction (Fig. 1) or in an axial or tangential direction (Fig. 2).

The size of these prisms, shown in "Forest Ecology and Management", A. Costa,

2003, pages 239-246, may be considerably variable, according to the following Table 1.

TABLE 1

Cell size

Prism height (μm) 30 - 40

Prism base (μm) 13 - 15

Average base (cm ² ) 4 - 6xlO ⁶

Wall thickness (μm) 1 - 1.5

Cell number/cm ³ 4 - 7xlO ⁷

According to "Proceedings of the Royal Society of London" Series A - Mathematical and Physical Sciences, from L. J. Gibson, 1981, pages 99-117, the cork side walls are very corrugated. Note that the process and device of the invention cause a decrease of wall corrugation.

Additionally, the closed structure of cork cells and its air content establish a low specific weight as well as some of the mechanical features of cork. However, the specific weight of cork may vary between 120 kg.m ³ and 240 kg.m ^'3 , as mentioned in "Boletim do Instituto dos Produtos Florestais" - Cork from M. Fortes, 1988, pages 65-68. This variability is related with cell size (wall height and thickness), corrugation of cell walls and amount of lenticels. As with above mentioned cork features, the specific weight of cork material subjected to process and device of the invention is lower than that before treatment.

Cork expansion process and device of the present invention provide a resulting expansion product which has less corrugation in the cell walls and an increased prism base size of about 30% (see Fig. 3). These cellular modifications express a volume increase and a specific weight reduction of used cork material. Accordingly, for example, the agglomerated cork blocks obtained are larger, lighter and more stable and

resistant than respective prior art blocks which were not subjected to the expansion process of the invention. These differences cause a significant yield and quality impact in the finished product which is highly desirable according to above mentioned natural limitations for obtaining cork material.

The features of the expansion process and device resulting product of the present invention will be described below in greater detail.

The expansion process of the invention may be used in continuous or batch mode and has three stages. The first stage comprises feeding of material followed of a second expansion stage and, finally, a third discharge stage or, preferably, cooling and discharge stage.

The shape of raw material which is intended to be supplied to process (for example, triturated or planks) does not pose any limitation to the expansion process.

Therefore, a first feeding stage comprises supplying of cork to an expansion zone.

In a continuous process, the feeding stage is designed to feed an expansion zone and, at the same time, to assure that process related steam is leak-free.

In a batch process, the feeding stage is designed to feed the expansion zone and recover steam remaining in that expansion zone.

With respect to second stage of process, so-called expansion, it comprises containment of cork material along with a saturated and/or overheated steam delivery for a time period, in a common zone named expansion zone.

In the expansion zone, cork material is subjected to saturated and/or overheated steam for a period in the range of about 30 seconds to 15 minutes, preferably in the

range of about 30 seconds to 5 minutes. During that time period, all cork material to be treated must be homogeneously exposed to saturated and/or overheated steam at a temperature in the range of about 150 - 340 ⁰ C, preferably in the range of about 280 - 310 ⁰ C and at an overpressure in the range of about 0.1 a 0.5 bar.

Finally, the third stage of expansion process, named discharge, comprises a discharge step, or preferably a cooling and discharge step, of the product which results from the second stage of expansion process. This stage comprises the collection of resulting product assuring containment of steam in the expansion and feeding zones, said cork collection being preceded by cooling.

Surprisingly, this new cork material expansion process imparts improved features

(described in more detail below) to resulting cork material (or resulting product) in relation to starting raw material which could have been subjected to pre-treatment. The expansion process of the invention requires a new device for its implementation in an effective and profitable way.

To better understand the present description it should be noted that the expression "contact time" is related to time period of contact between cork material and the saturated or overheated steam, in the expansion stage.

In terms of operation, the third stage of the expansion process is similar to first stage of process, excepting the fact that cork material is already expanded in third (and last) stage, whereby the expression "resulting product" is related to cork material which has already pass the second stage of process and, accordingly, is already expanded.

The term "overpressure" is related to pressure values that exceed the atmospheric pressure, whereby in order to obtain the full pressure value, it is necessary to sum up overpressure and atmospheric pressure.

With reference to Fig. 4 to 7, an expansion device that practices the expansion process of the invention is described.

The expansion device of the present invention should assure the following operative conditions:

- temperature: about 150 to 340 ⁰ C;

- overpressure: about 0.1 to 0.5 bar;

- contact time: about 30 seconds to 15 minutes.

Furthermore, the expansion device of the invention is made of three main assemblies UA, UE, UD (Fig. 4). These assemblies are directly related with the three stages of the expansion process above mentioned. Following, the assemblies UA, UE, UD will be designated by:

1) feeding assembly UA,

2) expansion assembly UE and

3) discharge assembly UD.

Each of these assemblies UA, UE, UD of expansion device of the present invention is hereinafter described in detail.

1) Feeding assembly

The feeding assembly UA of the invention supplies the expansion assembly UE (described below in detail). The configuration of the feeding assembly UA allows for

cork material admission, feeding of expansion assembly UE and sealing of steam used in the process.

Thus, with reference to Fig 4, said feeding assembly UA comprises a sealing member 3, a cork material admission 1 and a cork material conveying member 2.

As shown in Fig. 4, the sealing member 3 is arranged above admission 1 , sealingly connected to inlet opening of cork material admission 1 , at the first end of conveying member 2 and upstream of said feeding opening 6 of the expansion assembly UE. This sealing member 3 is designed to seal the feeding assembly UA, assuring the containment of saturated and/or overheated steam in the feeding and expansion assemblies UA, UE. For that purpose the sealing member 3 of feeding assembly UA should comprise a sealing means selected from the group consisting of feeding "hatchway", manual or electro-pneumatic sealing door, and an antechamber having two alternate entry /exit access points and the like.

Said admission 1 of feeding assembly UA is arranged in a first end of conveying member 2, connected to sealing member 3 and arranged below the latter. The admission 1 is suitable for reception of cork material to be expanded and for sending it to said conveying member 2.

It should be pointed out that the size and shape of admission 1 is related to the amount, type and shape of the cork material that is able to be supplied to the conveying member 2 without blocking takes place and, accordingly, excessive material in the conveying member 2. The design of the admission 1 is also related to the amount of cork material which can be treated in the expansion assembly UE at any moment, so as to assure a suitable and homogeneous contact of cork material with the saturated and/or overheated steam.

With respect to conveying member 2 of the feeding assembly UA, its function is to direct the cork material to be expanded to a feeding opening 6 of the expansion assembly UE.

The conveying member 2 of feeding assembly UA comprises a conveying means selected from the group comprising, worm screw, conveyor belt made of steel or any other suitable material, fluidization belt, pneumatic conveyor and the like and combination thereof, assuring the feeding of cork material to the expansion assembly UE.

Expansion assembly

Fig. 5, 6 and 7 schematically show several views of an expansion assembly UE of the invention (also herein referred as expansion chamber UE).

This expansion assembly UE is designed to enable the contact of the cork material with saturated and/or overheated steam. To this end, the expansion assembly UE receives the cork material to be expanded from the feeding assembly UA and then runs the expansion process of the invention. After expansion the assembly UE transfers the expanded cork material (also referred as the resulting product) to a discharge assembly UD to be described.

The expansion chamber UE comprises an housing 4 and a conveying and contact inner mechanism 5 within housing 4. Housing 4 is made of a suitable material and is of any shape that adjusts to configuration of said conveying and contact inner mechanism 5.

Said housing 4 of the expansion chamber UE is hollow and comprises openings for entry/exit of cork material, steam and thermofluid to/from the interior thereof.

Said wall openings of housing 4 of the expansion chamber UE comprise:

at least, one feeding opening 6;

at least, four saturated and/or overheated steam inlet openings 7;

at least, two steam outlet openings 8;

at least, one thermofluid inlet opening 9;

at least, one thermofluid outlet opening 10 and

at least, one discharge opening 11;

wherein

said, at least one, feeding opening 6 is arranged in a first end, on top, of the expansion chamber housing 4 (Fig. 5 and 6), for communication with the conveying member 2 of feeding assembly UA, and is designed to enable feeding the cork material to be expanded into the expansion chamber housing 4, so as to supply the cork material to the conveying and contact inner mechanism 5 to be described;

the, at least, four saturated and/or overheated steam inlet openings 7 are arranged in a lower portion of housing 4 of the expansion chamber UE (Fig. 6) and substantially uniformly located in the wall on either side do housing 4, thus being able to supply steam at desired conditions into the expansion chamber UE, by means of a boiler, for example;

said, at least, two steam outlet openings 8 are arranged and located along the top of housing 4 of the expansion chamber UE (Fig. 5) so as to allow flowing of the steam used in the expansion process inside the expansion chamber housing 4, the

outlet openings 8 acting as exhaust valves or converging, by tubes or pipes, to at least one exhaust valve outside the expansion chamber housing 4;

thermofluid inlet 9 and outlet 10 openings are arranged in the transverse face of a first end of the housing 4 (Fig. 7), but they can be arranged in any other suitable location of the expansion chamber housing 4. These openings 9, 10 operate, respectively, for admission and discharging a suitable fluid to the previous heating of wall of the housing 4, the circulation of the fluid and temperature control are performed by any known device of prior art and

the at least one discharge opening 11 is arranged in a second end of housing 4, opposite to the first end of feeding opening 6, at the lower portion of housing 4 (Fig. 5 and 6), connected to a collection and conveying member 13 of discharge assembly UD of the invention, and designed to enable delivery of the expanded cork material into discharge assembly UD to be described.

It should be appreciated that the term "thermofluid'' is related to any suitable fluid, known by those skilled in the art, which circulates inside tubing at the outer surface of the housing wall of expansion chamber UE in order to heat said wall when process starts, so as to avoid high temperature gradients inside housing 4 due to the contact with hot steam. Such gradients would lead to condensation and resulting yield reduction, in addition to water storage inside the expansion chamber housing 4, which would be harmful to the device and to the cork material to be expanded. Thermofluid is supplied and collected through, respectively, the inlet opening 9 and the thermofluid outlet opening 10, by any prior art device known by those skilled in the art. This latter device circulates or stops the thermofluid and maintains the correct operative temperature.

The conveying and contact inner mechanism 5 of expansion chamber UE of the present invention is located within the housing 4 of the expansion assembly UE, and assures the transport and a substantially uniform contact of the cork material to be

expanded with saturated and/or overheated steam, from the feeding opening 6 to the discharge opening 11 of the expansion chamber housing 4.

For this purpose, conveying and contact mechanism 5 receives the cork material, from the feeding opening 6 of expansion chamber housing 4, in one of its ends and conveys the cork material to the other end which communicates with the discharge opening 11 of housing 4. The cork material is moved from the discharge opening 11 to the discharge assembly UD. During transport of the cork material, this is subjected to physical contact with the environment of saturated and/or overheated steam inside the housing 4 of device of the invention. The temperature and pressure conditions are as that above mentioned, which cause the expansion of the cork material.

It will be appreciated that in order to obtain an optimized expansion of the cork material, the conveying and contact mechanism 5 should assure the contact of cork material with the enclosing environment in a substantially homogeneous way. Accordingly, the cork material should be revolved as it is moved from the feeding opening 6 to the discharge opening 11 , so that all its surface is equally subjected to saturated and/or overheated steam. Thus, the conveying and contact mechanism 5 must be able to perform this double function, and therefore it may have any suitable configuration such as one selected from the group comprising worm screw, conveyor belt made of steel or any other suitable material, fluidization belt, pneumatic conveyor and the like and combination thereof.

Also note that the conveying and contact mechanism 5 should be made of a resistant material, suitable to exposure to an environment of saturated and/or overheated steam and to the contact with cork material, as well as to a permanent operation.

At the end of the conveying course of the cork material, this will be in an expanded condition and, therefore, will be moved, through the discharge opening 11 , to the discharge assembly UD. At this time, the cork material is already expanded, thus being a resulting product of the expansion process and device of the invention.

Generally, the conveying speed of the conveying and contact mechanism 5 should be synchronized with the feeding and discharge speeds of respective feeding and discharge assemblies UA, UD of the invention, to avoid material jamming at the entrance or exit of the expansion chamber UE and, thus, to optimize the process yield. On the other hand, the speed of conveying and contact mechanism 5 depends on the intended contact time of the cork material with saturated and/or overheated steam and should be in accordance with above mentioned values, this is, in the range of about 30 seconds to 15 minutes.

It should be further noted that since the cork material expands along the conveying course, a conveying and contact mechanism 5 of the worm screw type or the like should have an increased pitch in the course direction to accommodate said cork expansion, thus avoiding the agglomeration of resulting product in the discharge opening 11.

The discharge assembly UD of expansion device of the present invention is hereinafter described.

Discharge assembly

The discharge assembly UD of the present invention is designed to discharge the resulting product of the expansion chamber UE, while assuring the containment of saturated and/or overheated steam in the expansion and feeding assemblies UE, UA.

For that purpose, the discharge assembly UD of the invention comprises a sealing member 12 and a collection and conveying member 13, respectively to seal said discharge opening 11 of the housing 4 of the chamber UE and collect the expanded cork material from the discharge opening 11 and convey it out of the expansion device to support assemblies (not shown), for subsequent storing, selection, treatment, etc.

The sealing member 12 of discharge assembly UD is arranged, at a first end of collection and conveying member 13, in the discharge opening 11 of expansion chamber housing 4, designed for sealing the opening 11 and, accordingly, for containment of saturated and/or overheated steam in the expansion and feeding assemblies UE, UA. Thus, the sealing member 12 of discharge assembly UD is selected from the group comprising feeding "hatchway", manual or electro-pneumatic sealing door, antechamber having two alternate entry /exit access points and the like and combination thereof.

The collection and conveying member 13 comprises a conveying means selected from the group comprising worm screw, conveyor belt made of steel or any other suitable material, fluidization belt, pneumatic conveyor and the like and combination thereof.

Due to the operative features, all the conveying mechanisms 2, 5 and 13 require a mechanical type driving or other. This driving will be selected from the group of means comprising mechanical, hydraulic, pneumatic, etc., which are not part of the invention and are well known of those skilled in the art. These driving means should be located outside of the expansion device of the invention, namely outside of the expansion chamber UE, in order to simplify maintenance without the need to stop or dismounting parts of the expansion device that would cause production and yield decreasing.

With reference to Fig. 13 and 14, in one embodiment of the present invention, and if cork planks are used, each of feeding and discharge assemblies UA, UD should comprise, at least, two sealing slides 14 having alternative motion, for plank admission and delivery.

Thus, in case of feeding assembly UA (Fig. 13), while one of the slides 14 receives the cork plank or planks, the other slide 14 is arranged above the feeding opening 6 of expansion assembly UE for delivering and, due to the reciprocate motion of the slides 14, in the next time they switch functions enabling, all the time, the collection

of cork planks by one of the slides 14 while the other is feeding the expansion assembly UE.

With respect to discharge assembly UD (Fig. 14), this comprises two sealing slides 14 (assuring the sealing of the expansion chamber UE) having alternative motion, respectively for the collection of expanded material and for discharge from the discharge assembly UD.

In a further embodiment of the present invention, at least two parallel operating expansion devices of the invention form an automated expansion apparatus supported by operative support equipment.

Fig. 15 schematically shows one such apparatus comprising two expansion chambers connected in parallel to each other.

The operative support equipment for supporting the expansion device of the present invention comprises, at least:

one boiler for steam production required in the expansion process;

one overheating apparatus at the expansion device inlet to set the desired final temperature for the expansion process;

one feeder of cork material for supplying raw material to the expansion device;

one condenser at the expansion device outlet to recover steam and to switch it into liquid stage for subsequent reusing thereof;

one device for recovering condensate from the expansion device for subsequent reusing;

one water reservoir connected to,

one system for cooling said condenser and for water restoring to compensate for steam leaks from the device;

one water filter;

one thermofluid circulation control device (not shown); and

one guide system (not shown) for product resulting from the expansion device (or set of devices) for delivery the expanded cork material into subsequent production process.

In still another embodiment of the present invention, with reference to Fig. 8 to 12 these show a preferred expansion device designed to expand grounded cork, comprising:

1) one feeding assembly UA',

2) one expansion chamber UE' and

3) one discharge assembly UD'.

Fig. 8, according to the above mentioned expansion device, shows one feeding assembly UA' of the preferred device comprising, respectively, one sealing hatchway 3', one admission hopper 1 ' and one conveying worm screw 2', wherein the sealing hatchway 3' is located above the admission hopper 1', which, in turn, is located in a first end of the conveying worm screw 2' and placed perpendicularly to the latter.

Said sealing hatchway 3' is sealingly arranged in the upper end of the admission hopper 1 ' , for containment of overheated steam in the feeding and expansion assemblies

UA', UE'. Note that the cork material to be expanded will be moved from the sealing hatchway 3' to the admission hopper 1'.

The admission hopper 1' is of parallelepiped shape, tapered in the lower end and open in its upper and lower ends. The upper end opening is sealingly connected to the sealing hatchway 3' and is designed to receive grounded cork from a feeding conduit which is well known of those skilled in the art. The lower end opening faces the conveying worm screw 2', the admission hopper 1' being perpendicularly arranged in relation to conveying worm screw 2' in order to supply the latter with grounded cork.

Said conveying worm screw 2' receives grounded cork from the first end of the admission hopper l 'and convey it to a cork material inlet 6' of the expansion chamber UE'.

Fig. 9 to 11 show several views of a preferred expansion chamber UE' of the present invention. In this embodiment the expansion chamber UE' comprises, one cylindrical chamber housing 4' and one conveying and contact worm screw 5' inside the housing 4', the housing 4' comprising:

one cork material inlet 6';

two overheated steam inlets 7';

four steam outlets 8";

one thermofluid inlet 9';

one thermofluid outlet 10' and

one expanded material outlet 11 ';

wherein

said cork material inlet 6' is arranged in a first end, on top, of housing 4' of the expansion chamber UE ¹ , and is designed to supply cork material to be expanded into the housing 4' (Fig. 9 and 10);

said two steam inlets T are arranged outside and laterally, one on either side of chamber housing 4', each splits into, at least, two steam inlet openings 7" arranged on either side of chamber housing 4', for a more uniform delivery of steam into the expansion chamber UE' (Fig. 10 and 11);

four steam outlets 8" are located along the top of the expansion chamber housing 4', converging to a single steam exhaust valve 8' arranged outside and above the chamber housing 4' (Fig. 9, 10 and 11);

said thermofluid inlet 9' and outlet 10' are arranged in the transverse face of the first end of chamber housing 4' (Fig. 9, 10 and 1 1) and

said expanded material outlet 11 ' (Fig. 9) is arranged in a second end of housing 4' opposite to first end of housing 4', at the lower portion of housing 4', to enable delivery of the expanded material into the discharge assembly UD'.

With reference to Fig 9, this shows a conveying and contact worm screw 5' to convey cork material to the expanded material outlet 11 ' while assures a substantially uniform contact of the of cork material with overheated steam.

With reference to Fig 12, a discharge assembly UD' according to this embodiment is shown comprising, one sealing hatchway 12' and one collection and conveying worm screw 13'.

Said sealing hatchway 12' of the discharge assembly UD' is arranged, in the resulting product outlet 11 ', in a first end of collection and conveying worm screw 13' and is designed for containment of saturated and/or overheated steam in the expansion and feeding assemblies UE', UA'.

The collection and conveying worm screw 13' of discharge assembly UD' collects the expanded cork material from the resulting product outlet 11 ' of expansion chamber UE' and convey it out of preferred expansion device.

The features of the resulting product of the present expansion process and device is hereinafter described in detail.

Surprisingly, it has been found that, in result of the expansion process and device of the present invention, the resulting product exhibits improved features, namely physical and mechanical properties, without showing macroscopic differences or compromising its commercial value. The main differences are essentially:

i) corrugation of cell walls and, accordingly, the reduction of its size,

ii) specific weight of the material and

iii) ultimate strength and dimensional stability of agglomerated cork produced from expanded cork.

Thus, the resulting product of the present expansion process and device exhibits, in relation to its physical properties, a size increase (Fig. 3). After subjection to the expansion process and device of the invention, the average size of the prism base of cork cells increases from 13 μm to 17 μm, which is a 30% raising. Therefore, the cork material obtained after the expansion is different, as it shows bigger cells and slightly thinner walls. This modification is very significant as it provides the resulting product

with a substantial volume increase of about 30%, which largely improves the material yield.

With reference to Table 2 below, after subjecting cork material to the expansion process and device of the invention, the cork material specific weight substantially decreases due to above mentioned increasing of cell size, of about 15-30% . This reduction of cork specific weigh, in addition of being connected to a material yield increase (less material used for the same application), is also connected to a cork quality improvement (that increases with a reduction in the cork specific weight) which represents a commercial gain.

TABLE 2

With reference to Table 3 below, with respect to ultimate strength of the agglomerated expanded cork obtained from the new expansion process and device, an increase from 30% to 60% was found, this is to say, said agglomerated expanded cork

from the process and device of the present invention has ultimate strength values about 30% to 60% higher than prior art agglomerate cork obtained from cork raw material not subjected to the expansion process. This also represents a commercial gain.

TABLE 3

Tables 1 and 2 support the above mentioned in relation to cell size and specific weight values of cork samples, before and after the submission to the expansion process and device of the present invention

Subjecting cork raw material to the new expansion process and device for 30 seconds to 15 minutes enables expansion of the starting material in the range of 5 to 30% . During the process, the moisture remains unchanged and the specific weight decreases.

When subjected to the expansion process and device of the invention, the cell size of cork selected from the group comprising falca cork, virgin or reproduction cork, cork planks, cork residues (from the production of stoppers or cork plank transformation), grounded, granulated and powdered cork, increases about 30% . This cell size growing, in addition to cause a reduction in the specific weight of the resulting cork material,

increases the cork material yield (as may be assessed in a subsequent granulation process).

The granulated cork produced from the expanded cork material of the present process and device has a significant ultimate strength increment ranging between about 30% and 60% .

When subjected to new expansion process and device of the invention, the falca cork cork, virgin or reproduction cork, cork planks, cork residues (from the production of stoppers or cork plank transformation), grounded, granulated or powdered cork, exhibit a volume increase up to about 30%, which results in less specific weight, higher cell size, higher ultimate strength and improved stability of the agglomerate blocks made from said cork material.

The new expansion process and device does not suffer from the prior art related drawbacks of cork material degradation due to the use of very high temperatures, above 350 ⁰ C.

Examples of the present expansion process and device and respective results are hereinafter disclosed.

EXAMPLES

Example 1: Cork material subjected to saturated steam in a batch expansion process.

Samples of grounded cork were brought in contact with saturated steam for several periods of time with different pressures. The results of the expansion (see Table 4 below) show a 20% expansion of the tested samples.

TABLE 4

Example 2: Cork material subjected to overheated steam in a batch expansion process.

Grounded cork was subjected to overheated steam at a 200 ⁰ C temperature with an overpressure of 0.6 kg/cm2 during 8 minutes. These conditions allowed for an apparent expansion of about 30% .

Example 3: Cork material subjected to saturated steam in a continuous expansion process.

Different types of broken cork were subjected to the cork expansion process with overheated steam for periods of 1 minute. The expansion results, shown in Table 5 below, demonstrate one expansion of about 13% to 26% in the tested samples.

TABLE 5

Example 4: Cork material expansion with overheated steam, wherein the resulting cork material was subsequently grounded.

One batch of boiled broken cork was subjected to the cork expansion process of the invention with overheated steam for periods of 1 minute. After the expansion process, cork was subjected to a traditional granulation process and the resulting granulated material was compared with granulated material of the prior art. With reference to Table 6 below, it was found that a decreasing in the specific weight of the granulated material took place and also an improvement in the quality of materials, for example, increase of the amount of low density granulated material.

TABLE 6

Example 5:

An expansion device of the invention is supplied with granulated cork having a grain size of about 2 to 40 mm. The operative conditions comprise a temperature in the range of about 280 to 310 ⁰ C, overpressure in the range of about 0,1 to 0,5 bar and contact time in the range of about 1 to 2 minutes, which allow obtaining expansion values in the range of about 7 to 25 % .

The examples of the expansion process of the invention are supported by Table 4 showing percentage values of the expansion that takes place in a cork material subjected to steam in a batch expansion process, and by Table 5 which shows expansion values for cork material expanded in a continuous expansion process.

It should be appreciated that the new process and device for cork material expansion by saturated and/or overheated steam may be subjected to various modifications within the scope of the appended claims.