WO2014170165A2

WO2014170165A2 - Conditioning device of granular material contained in a storage facility and storage facility incorporating said device

Info

Publication number: WO2014170165A2
Application number: PCT/EP2014/057015
Authority: WO
Inventors: Jaime BRAVO VEGA; Luis Alfonso Fernandez Orive; Alesander Olea Abarrategi; Ekaitz Barrasa Artamendi
Original assignee: Loramendi, S.Coop.
Priority date: 2013-04-17
Filing date: 2014-04-08
Publication date: 2014-10-23
Also published as: ES2510090B1; ES2510090R1; ES2510090A2; WO2014170165A3

Abstract

Conditioning device suitable for conditioning, i.e., cooling or heating, granular material contained in a storage facility (3), preferably a silo, and storage facility (3) comprising said device (1 ). The device (1 ) comprises distribution means (4) which allow distributing airflow towards the granular material contained in the storage facility (3). Said device (1 ) also comprises regulating means (5) which allow adjusting the temperature of the airflow reaching the distribution means (4). Said regulating means (5) comprise at least one vortex tube, where said vortex tube generates hot airflow (F_h) and cold airflow (F_c) from an air inlet (F_e). One of said airflows (F_h, F_c) is transferred to the distribution means (4).

Description

DESCRIPTION

"Conditioning device of granular material contained in a storage facility and storage facility incorporating said device"

TECHNICAL FIELD

The present invention is related to devices that condition granular material contained in a storage facility, for example a silo.

PRIOR ART Silos comprising granular material such as grains, seeds, sand, bentonite, etc., for example are known. Sand molding machines or machines for making sand cores of an iron foundry, for example, comprise such silos for storing sand. These silos comprise a reduced conical or pyramidal section at the bottom thereof comprising a discharge chute to allow discharging the product contained in the silo. The sand that will form the flasks or the sand that will form the sand cores must comply with a series of requirements as regards temperature, moisture, etc., to enable being used as such. The sand working parameters should be as stable as possible, therefore, depending on the environmental conditions, the sand contained in the silo needs to be heated sometimes and cooled other times.

In this sense, sand storage silos comprising a fan and resistors for circulating a hot airflow through the material contained in the silo to heat said material are known.

Sand storage silos comprising a plurality of tubes arranged inside the silo where water circulates cooling the sand when said sand passes through said tubes are also known.

Silos in which a (cold or hot) airstream is circulated through a layer of grain to lower or reduce the moisture of said layer are also known. In this sense, ES1005495 U discloses a cylindrical silo that stores cereal grains. The lower part of the silo is inverted cone-shaped and comprises a surface with perforations to make the passage of the air that is forced through a fan easier. The silo also comprises a cone, such that it faces the inverted cone of the lower part of the silo, arranged at the bottom of the silo such that it allows metering or restricting the passage of cereal grains towards the discharge chute where there is arranged a screw feeder.

DISCLOSURE OF THE INVENTION An object of the invention is to provide a conditioning device of granular material contained in a storage facility, such as a silo for example, as described below.

Another object of the invention is to provide a storage facility, such as a silo for example, comprising said conditioning device.

The conditioning device of the invention is suitable for conditioning granular material contained in a storage facility, such as a silo for example. Said device comprises distribution means which allow distributing airflow towards the granular material contained in the storage facility. Said device also comprises regulating means which allow adjusting the temperature of the airflow reaching the distribution means. Said regulating means comprise at least one vortex tube, where said vortex tube generates hot airflow and cold airflow from an air inlet. One of said airflows is transferred to the distribution means. A considerable amount of granular material contained in the storage facility (if the granular material is sand, for example, a sufficient amount for forming a sand mold) is cooled or heated with the conditioning device of the invention, minimizing the time required for that purpose in an effective and economical manner, and at the same time it enables reducing process cycle times of the apparatus or machines beyond the storage facility. Said device also prevents the granular material from compacting or caking and/or adhering to the walls of the storage facility, thereby making the passage of the air through the granular material easier because it assists in fluidizing the granular material. These and other advantages and features of the invention will become evident in view of the drawings and detailed description of the invention.

DESCRIPTION OF THE DRAWINGS

Figure 1A shows a first diagram of a silo comprising a first embodiment of the conditioning device according to the invention.

Figure 1 B shows a second diagram of a silo comprising a second embodiment of the conditioning device.

Figure 2 is a cross-section view of a vortex tube comprised in the conditioning device of Figure 1A.

DETAILED DISCLOSURE OF THE INVENTION

The conditioning device 1 of the invention is suitable for conditioning, i.e., cooling or heating, granular material contained in a storage facility 3, such as a silo. Said device 1 comprises distribution means 4 which allow distributing airflow towards the granular material contained in the storage facility 3. For the sake of clarity, said granular material is not depicted in the drawings. Said device 1 also comprises regulating means 5 which allow adjusting the temperature of the airflow reaching the distribution means 4 to the desired temperature. Said regulating means 5 comprise at least one vortex tube, where said vortex tube generates hot airflow F_h and cold airflow F_c from an air inlet F_e, as shown in Figure 2. One of said airflows F_h or F_c is transferred to the distribution means 4. Said airflow can thus fluidize the granular material contained in the storage facility 3 and at the same time heats or cools said material. Fluidize is understood to mean that the granular material behaves like a fluid at rest, i.e. without generating a turbulent movement of said material to make the passage of said airflow easier. The granular material is therefore prevented from compacting or caking and/or adhering to the walls of the storage facility 3.

The embodiment of Figure 1A shows a silo 3 comprising sand, for example sand of the type needed to form a sand mold that is suitable for molding iron or aluminum castings or for forming sand cores. Even though the description hereinafter refers to sand (of any type) as the granular material, the following description is also valid for granular materials of any type that can form a fluidized bed, for example bentonite or grains.

The silo 3 of Figure 1A is cylindrical and comprises a substantially inverted cone- shaped bottom 3a, although it could also be an inverted pyramid-shaped bottom 3a. The silo 3 also comprises at least one cone 3' arranged inside the silo 3, preferably close to the bottom 3a of the silo. In the examples of Figures 1A and 1 B, the silo 3 comprises a single cone 3'. Said cone 3' can be cone-shaped or pyramid-shaped and is arranged such that it faces the inverted cone or pyramid at the bottom 3a of the silo. Said cone 3' allows forming an internal heating or cooling chamber for heating or cooling the granular material, the sand in the example of Figure 1A, in the direction of the material contained at the bottom 3a of the silo, said bottom in the example of Figure 1A being an inverted cone-shaped bottom 3a, such that it prevents heating or cooling the rest of the material contained in the silo 3, leading to considerable energy savings and a considerable reduction of the time needed for the sand to obtain the desired working temperature, while in the same manner enabling a reduction of subsequent production process cycle times (for example, in a molding line cycles times very often overlap, so reducing the time for preparing the sand can lead to reducing the cycle time if the manufacturing process allows it, i.e., it prevents the preparation of the sand from being the bottleneck in the molding line). The amount of material contained at the bottom 3a of the silo is the necessary one for supplying the necessities of subsequent processes. Therefore, in the example of Figure 1 A the amount of sand that is heated or cooled is the amount that is sufficient for forming for example a sand mold.

The regulating means 5 are connected to a compressed air source, not shown in the drawings, such that the air inlet F_e of the vortex tube is connected to said compressed air source.

Generally, the temperature of the compressed air supplied directly by a compressed air source is insufficient in most cases for cooling or heating the granular material contained in the storage facility 3, such that it is not possible to condition said granular material at the desired temperature. Therefore, the conditioning device 1 of the invention assures that the granular material contained in the storage facility 3, at least the amount contained at the bottom 3a of the storage facility, reaches the ideal working temperature, regardless of climate or environmental conditions of the surrounding area (temperature differences in summer and winter, geographical location of the storage facility, etc.).

As shown in Figure 2, the vortex tube 5 comprises an inlet conduit F_e which is preferably connected to a compressed air source (not depicted in the drawings) in the example of the embodiment of the invention. The vortex tube generates hot airflow F_h and cold airflow F_c from said air inlet F_e. As the operation of a vortex tube is well known in the state of the art, details concerning said tube will not be provided in the description.

By varying the flow rate or the inlet pressure of the inlet flow F_e of the vortex tube, and even by varying structural parts of the vortex tube, it is possible to control the flow rate and the temperature of the hot discharge flow F_h and cold discharge flow F_c. Therefore, the conditioning device 1 of the embodiment of the invention allows very precisely adjusting the discharge temperature of the granular material before it is extracted through the discharge chute 6. Said discharge chute 6 is arranged in the lower part of the bottom 3a of the storage facility and the discharge of said material is regulated by a gate or valve (not shown in the drawings) arranged in the discharge chute 6 which opens or closes on demand. The granular material to be extracted is a portion of the material that is arranged at the bottom 3a of the storage facility. Therefore, if the temperature of the material contained in the silo 3 shown in Figures 1 A or 1 B is desired to be raised, or at least the temperature of the material contained at the bottom 3a of the silo, one must simply connect the discharge chute of the vortex tube transporting the hot airflow F_h to the distribution means 4, such that the hot airflow F_h is transferred to said distribution means 4. If in contrast the temperature of the material contained in said silo 3, or at least the temperature of the material contained at the bottom 3a of the silo, is desired to be lowered, one must simply connect the discharge chute of the vortex tube transporting the cold airflow F_c to the distribution means 4, such that the cold airflow F_c is transferred to said distribution means 4. The distribution means 4 are preferably arranged inside the storage facility 3, although arranging said means 4 such that they are attached to the storage facility 3 is not ruled out.

An option not shown in the drawings could be to combine the use of the vortex tube with additional means for conveniently supplying hot or cold air, such as fan means and/or resistors, for example.

Since the cold discharge airflow F_c of the vortex tube can reach negative values, the cooling power of the regulating means 5 of the device 1 of the invention is very efficient and allows very precisely controlling the temperature of the material right before it is extracted through the discharge chute 6.

An option not shown in the drawings could be to combine the use of the vortex tube with additional means for conveniently adding heat to or removing heat from the granular mass, such as condensation and evaporation means, for example.

The distribution means 4 of the conditioning device 1 can be carried out in different ways, for example it can comprise a filter mesh or membrane (not shown in the drawings) which comprises substantially homogenously-sized particles forming a porous surface and which can be obtained by sintering, for example, or it can comprise at least one perforated tube 4b. The airflow distributed through said membrane is distributed at the same pressure at all points, thereby preventing preferred paths. The membrane can be metallic, ceramic or made of any other material capable of performing said function. The distribution means 4 of the embodiment of the example of Figure 1A comprise an array, i.e., a plurality, of perforated tubes 4b that are connected to one another. Said perforated tubes 4b are longitudinal tubes and they are arranged inside the silo 3, preferably in the area of the bottom 3a of the silo, and preferably below the cone 3' as shown in Figure 1A. Likewise in the embodiment of the example of Figure 1A, the perforated tubes 4b are connected to the regulating means 5 through an intermediate conduit 4a attached to the outer surface 3b of the inverted cone of the bottom 3a of the silo as shown in Figure 1A, therefore the regulating means 5, i.e., the discharge chute, of the vortex tube transporting the hot airflow F_h or the discharge chute of the vortex tube transporting the cold airflow F_c, are connected with the intermediate conduit 4a and the intermediate conduit 4a is connected with the perforated tubes 4b. Perforations in the tubes 4b allow discharging the airflow coming from the supply or regulating means 5 such that said airflow contacts the granular material contained in the silo 3, i.e., the sand in the example of Figure 1A. In an embodiment that is not contemplated in the drawings, it is also optionally possible to dispense with the intermediate conduit 4a. In this case, the discharge chute of the vortex tube transporting the hot airflow F_h or the discharge chute of the vortex tube transporting the cold airflow F_c would be connected directly with the at least one perforated tube 4b or the array of perforated tubes 4b. It is also optionally possible to replace said array of perforated tubes 4b with another element that allows homogenously distributing the air in the same location in the silo, such as a channel with air discharge nozzles 4c, for example, as seen in the embodiment of the example of Figure 1 B, or with the membrane described above. It is also possible to use a combination of several distribution means, such as the array of perforated tubes and the membrane, for example.

Claims

1 . Conditioning device of granular material contained in a storage facility (3), for example a silo, said device (1 ) comprising distribution means (4) which allow distributing airflow towards the granular material contained in the storage facility (3), characterized in that said device (1 ) also comprises regulating means (5) which allow adjusting the temperature of the airflow reaching the distribution means (4), said regulating means (5) comprising at least one vortex tube, said vortex tube generating hot airflow (F_h) and cold airflow (F_c) from an air inlet (F_e), and one of said flows (F_h, F_c) being transferred to the distribution means (4).

2. Device according to claim 1 , wherein the cold airflow (F_c) is transferred to the distribution means (4).

3. Device according to claim 1 or 2, wherein the air inlet of the vortex tube is connected to a compressed air source.

4. Device according to claim 1 , wherein the hot airflow (F_h) is transferred to the distribution means (4).

5. Device according to any of claims 1 to 4, wherein the distribution means (4) comprise a membrane comprising a porous surface or at least one perforated tube (4b) arranged inside the storage facility (3), preferably at the bottom (3a) of the storage facility.

6. Device according to claim 5, wherein the distribution means (4) comprise a plurality of perforated tubes (4b) connected to one another.

7. Device according to claim 5, wherein said membrane comprises homogenously sized particles.

8. Device according to any of claims 5 to 7, wherein the regulating means (5) are connected with said at least one perforated tube (4b) or said membrane.

9. Device according to any of claims 5 to 7, wherein the distribution means (4) also comprise an intermediate conduit (4a) attached to the outer surface (3b) of the inverted cone at the bottom (3a) of the storage facility, said intermediate conduit (4a) being connected to said at least one perforated tube (4b) or said membrane.

10. Device according to claim 9, wherein the regulating means (5) are connected with said intermediate conduit (4a).

1 1 . Storage facility, preferably a cylindrically shaped storage facility such as a silo, suitable for containing granular material, characterized in that it comprises a conditioning device (1 ) according to any of claims 1 to 9.

12. Storage facility according to claim 1 1 , comprising an inverted cone-shaped bottom (3a).

13. Storage facility according to claim 1 1 , wherein the storage facility (3) comprises an inverted pyramid-shaped bottom (3a).

14. Storage facility according to any of claims 1 1 to 13, comprising at least one cone or pyramid (3') arranged inside the storage facility (3), preferably close to the bottom (3a) of the storage facility.

15. Storage facility according to claim 14, wherein the distribution means (4) of the conditioning device (1 ) are arranged below said cone or pyramid (3') arranged inside the storage facility (3).