EP2315496B1

EP2315496B1 - Apparatus for continuous drying of bulk materials

Info

Publication number: EP2315496B1
Application number: EP10011703A
Authority: EP
Inventors: Amadeo Pagotto
Original assignee: SMC TECHNOLOGY Srl
Current assignee: SMC TECHNOLOGY Srl
Priority date: 2009-10-20
Filing date: 2010-09-29
Publication date: 2012-01-25
Anticipated expiration: 2030-09-29
Also published as: ITTV20090204A1; ES2379940T3; EP2315496A1; IT1396318B1; ATE543370T1

Abstract

Apparatus for fast and continuous drying and dehumidification of bulk materials and process with a plant for drying, dehumidifying bulk materials, in which the treatment chamber includes adjacent container modules along said linear path, which are transversally placed with respect to said linear path, each of them having a cradle cross section, wherein each container module comprises at least one tilter device and it is separated from the other one by a separating plate which is adjustable in height so that said bulk material overflows over the respective top edge of the separating plate and it flows down in the adjacent transverse container module with cradle section.

Description

This invention relates to a multi-purpose modular apparatus with continuous fluidized evaporation-drying function for treating bulk materials or granular materials, and the process with the dehumidification-drying plant of said bulk material.

Application field

In principle, many materials, both natural materials and raw materials and even semi-finished materials, e.g. granulated plastic materials for molding devices to manufacture plastic products, or foodstuffs as cereals, or different products as drugs, once gathered they can have more or less high humidity percentages, which are undesirable or not adequate for following treatments, e.g. preservation and packaging.
The invention finds particular even though not exclusive application in the field of the treatment of bulk or granular materials, which are conventionally indicated as materials, with regards to which one needs to control the humidity percentage which is present in them in a precise way.
It is known that in order to allow the use of said materials which are not treated in the productive chains, and in particular with the purpose of improving the yield and the quality of the finished product, it is often necessary to reduce the humidity percentage which can be originally found. For example, this is the case of cereals, as the grain, which would give rise to fermentation if it is even temporarily gathered in large containers or packaged for long periods, without any treatment, with a non controlled humidity percentage. It is also the case of plastic material granules which are needed to feed molding plants, with regards to which, noticeably, the more the humidity percentage at the packaging differs from the requirements of the molding lines, the more further treatments will be needed in place that is prior to their use, with a consequent time and money expenditure, in order to obtain the required humidity levels.
It was therefore useful to conceive devices and processes substantially having the main purpose to control if not to totally eliminate the humidity percentage, until reaching the drying of the product. These processes and the related devices intended to use devices able to obtain the evaporation of the water, which is an aim that was reached by means of the use of thermal energy or with the aid of dry gases. In the cases in which the treatment of dynamic materials as bulk materials is provided, said processes can also provide their fluidification, following a determined path along a treatment horizontal line, which is divided in more than one stage.

Prior art

In literature, solutions are concretely known providing a drying tunnel for bulk materials. For example in the web site http://www.drygenic.com of the company Ventilex b.v. some solutions are described comprising a belt and a fluid bed, which propose different tunnel solutions to horizontally control or dry foodstuffs, chemicals, pharmaceutical and other products. Also in patent literature rights are known which intended to solve in a more or less effective way the problem relative to the humidity control and drying.
For example, US2419875 (Birdseye ) describes a container to dry food with extreme rapidity. It is a container, inside of which more than one intercommunicating compartments are provided which are vertically aligned, wherein in each compartment a corresponding horizontal conveyor belt is housed and over it, on the ceiling, relative heat radiating means are present directed towards the underlying conveyor belt. The product which is fed by gravity from above is laid on the first conveyor belt, which on the other side, after its stroke, will let the material fall on the underlying area through an opening which introduces the material at the conveyor belt of the underlying compartment and so on. The last stages are not provided with the heat radiating means. Finally the contribution of a de-hydrating dry hot gas is provided. DE2246027 (Püschner ) is relative to a conventional dryer with more than one conveyor belts, which are divided in separate compartments, inside of which a fluid circulates in order to bring the environment at a certain temperature. In US5189809 (Bailey ), vibrating panels are provided which receive the material to be treated, the lower panel of which is subjected to the action of infrared rays. US3742614 (Bettermann ) is a device for the thermal treatment of powdered or granular materials, including a container with a plurality of circular trays mounted one above the other in said container for the sequential transfer of the material downwardly, a selective trays-temperature control system, and a vibrating device for the vibrating trays for moving the material towards the successive stages with preselected layer depths.
DE4036112 (Heindl ), describes a horizontal cylindrical container for drying along which two conveyor belts are located one of which is partly superimposed to the other one. The material is introduced through an upstream opening and then it is directed downstream. At least in a corresponding region, where the material is heated by means of microwaves, a gas is passed from above towards the bottom or vice-versa. The matter to be treated is in a granular form or in the form of fibers. US3063848 (Van Gelder ) consists of a treating apparatus by means of a dehydration process of bulk foods. The apparatus has more than one vibrating plates, which are divided in two opposite groups, with alternating and superimposed inclined plates in such a way that the lower ends of each of them are located at the top of the underlying inclined plate. A peripheral circuit supplies hot air to an air space which is provided along the vibrating plate at the region under the collection plate of the material to be treated. In one case, the hot air can be combined with dehydrating gases, and supported by single ventilation units, all of which feeding at the air space underlying the collection plane of the material to be treated. The air which is forced into the air space of the vibrating plate is conveyed upwardly causing a floating effect of the material to be treated. In this case the supporting plane consists of a net woven from a stainless steel wire.

Prior art closest to the invention

D1 IT1358665 (Pagotto ) relates to a modular apparatus with continuous fluidized evaporation-drying function for treating bulk materials or granular materials, and to a thus obtained discontinuous modular plant, in which at least one modular apparatus includes:

a main chamber at a controlled atmosphere, for treating bulk or granular materials, with a continuous tunnel having a linear path, which, at the main chamber which is heated by microwave devices, is provided with an underlying fluid bed supporting the material, which receives upstream the material to be treated by means of falling, a corresponding exit of the thus treated material being provided downstream;
along the main chamber at a controlled atmosphere, at least one secondary chamber intercommunicating with said first one obtained in the underlying part of the fluid bed supporting the material, in which secondary chamber a forced airflow circulates cooperating with heating means;
a possible vacuum pump group to control the atmospheric pressure of the main chamber;
a logic control unit of the apparatus, which also individually controls and lets the single functions interact with each other, respectively ventilation, temperature and atmospheric pressure, by means of sensor means;

Finally in D2 IT1358667 (Pagotto ) a microwaves dehumidification apparatus is described composed by a hopper and a horizontal treatment chamber, in which at the bottom of the horizontal chamber a sintered sheet is obtained which is tangent to the Archimedean screw and developing for the whole length of the same, under which an air space is obtained for the distribution of a dried air flow at a controlled temperature coming from one underlying heating chamber with which it is in communication through at least one intake.
In conclusion, summarizing the thus obtained information one can reasonably consider as known:

apparatuses for continuously treating material with a linear multistage path developing in a horizontal direction, which are commonly called "tunnel";
tunnel apparatuses, providing vibrating plates, one after the other, along which the material to be treated flows down by gravity, also with the contribution of a fluid bed;
apparatuses which use hot air flow generators with a convective motion for the material treating; or apparatuses with dry gas circulation, alternatively a flow of hot air combined with some dry gas; or still apparatuses using hot air flow generators with a convective motion supporting the action of microwave devices which are located in the area above the path of the material to be treated;
an apparatus with a horizontal treatment chamber along which microwaves generators operate, to dry and dehumidificate the bulk material, with an underlying sintered plate through which a hot airflow passes.

Drawbacks

The above-described apparatuses have some drawbacks, and in particular those referred to the closest prior art. In principle, it is possible to say that the known solutions require great sizes, above all with reference to the length. For example in D1, to obtain a proper treatment, a translation plane is proposed which includes a fluid bed which, depending on the required treatment, needs a path which particularly develops in length and this occurs depending on the different material treatment stages. From a practical point of view it follows that particularly proper sites are needed to house thus sized plants, the latter circumstance being not always achievable and in any case being a very binding condition. Still in D1, in the case of treatments of highly hygroscopic materials, the single fluidification of the material by means of the air flow does not appear to be sufficient to allow a fast and homogenous treatment, even if with the participation of vibrating planes. In these cases indeed the material aims to group in aggregates, this being a circumstance requiring a more effective fluidification and a fluidification which is functional to the separation of the same. D2 can provide for this situation by providing a fluidification Archimedean screw longitudinally developing with respect to the treatment chamber. In this case the apparatus is configured for the linear treatment of small material quantities, while it appears unsuitable for large material quantities. Furthermore, with reference to D2 it must be pointed out that it does not carry out a treatment by means of different stages, thus involving a reasonable difficulty in controlling the residual humidity percentage which can differ very often with respect to the values which are set in the logical unit controlling the plant.
Still a disadvantage is relative to the fact that the apparatuses suggested by D1 are not particularly economical, due to the fact that they are complex apparatuses, and however they require a constant and careful maintenance. Vice-versa D2, though resulting in less complex solutions with respect to the ones provided by D1, does not allow the material treatment in an intermediate quantity between the two solutions proposed by D1 and D2, resulting substantially inadequate and from the practical point of view being impossible to be implemented by means of additional modules.
An essential aim of the present invention is also to avoid the abovementioned drawbacks.

Brief description of the present invention

This and other aims are reached by the present invention according to the characteristics as for the included claims, solving the abovementioned problems by means of a multi-purpose modular apparatus with transverse cradle-modules, for fast and continuous drying and dehumidification of bulk materials and process with a plant for drying, dehumidifying bulk materials, said modular apparatus comprising at least one treatment chamber of the bulk materials, with:

(a) a multiple processing stage linear path developing on a horizontal plane, comprising an upstream entry and a downstream discharging exit of the bulk material;
(b) microwaves generators located along said linear path and orientated in such a way as to direct the microwaves bundle inside said treatment chamber;
(c) means generating a controlled hot air flow, which is introduced into said treatment chamber of the bulk materials, wherein said controlled hot air flow passes through the fluidification bottom which is obtained along and at the base of said multiple stage linear path;

Aims

In this way, by means of the considerable creative contribution whose effect constitutes an immediate technical progress, some aims are achieved. A first aim is to allow a significant containment of the sizes of the plant. This was made possible by configuring the apparatus in such a way as to arrange each of the cradle modules according to an orientation in such a way as to have a transverse position with respect to the advancing direction that is with respect to the path which is followed by the bulk material to be treated. Moreover, the original separation of the respective cradle modules, by means of the plates, helps to contain the material to be treated and its prosecution along the treatment path in a proper way and quantity, being it transferred from an upstream cradle module to the downstream adjacent one, simply by excess and gravity. The independent adjustment in height of the plate of each of the cradle modules indeed allows to dose and therefore to control the material quantity which passes at any time from a cradle module to the adjacent one. It follows that adequately by managing, for example by means of proper control systems operated by a logical unit, the height of the separating plates also and in conjunction with the speed of the tilters which are present in each of the cradle modules, as well as the speed of the air flow coming from the underlying fluidification bottom, it is possible to change the amount of material to be treated in each of the cradle modules as well as, by acting on the speed, it is possible to control their staying time inside of it, in such a way as to obtain working stages which can also be different from one another specifically adapted depending on the required treatment cycle.
An additional aim refers to the versatility due to the fact to be able to use more than one module which can be assembled with each other, the modules being able to comprise the cradle module unit, as well as an analogous apparatus for example consisting of more than one cradle module, which is adjacent to a first one, allowing a different and rational arrangement of the same, in such a way as to always limit the development in length, reducing at the same time the construction complexity of the plant, without modifying the effectiveness of the conditioning cycle. In conclusion it allows a greater flexibility, both in the plant construction phase, and in the case in which the apparatus must be modified to optimize different treatment cycles, with the aim to satisfy the most multiple needs. The possibility to obtain the capacity of the plant itself, therefore changing the number of the cradle modules, with simple solutions, for example by means of on line combination of analogous modules, it allows to perform material conditioning cycles which are different from one another, and as a result not limiting the user to the plant type which was originally bought. From the point of view of the production of the apparatuses the advantages are evident for the enterprise, supposing that a more rational management of the components is allowed with a good ability to rationally and functionally fulfill the orders at low costs orders and in very short times.
These, but also other advantages or aims will be apparent from the following detailed description of some preferred embodiments with the aid of the enclosed schematic drawings whose embodiment details are not to be considered limitative but only illustrative.

Content of the drawings

Figure 1 , is a side-view of a modular apparatus with cradle modules, having an evaporation-drying function;
Figure 2 , is a cross sectional view of the apparatus of Figure 1;
Figure 3 , is the lay-out of a plant including the modular apparatus having an evaporation-drying function as for figures 1 and 2.

Practical description of an embodiment of the invention

Also with reference to the figures, it can be observed that a modular apparatus 10 having an evaporation-drying function in a continuous way, for the conditioning of granular or bulk material along a tunnel, consists of a frame 100 which includes support legs 101 supporting a superstructure composed by a substantially parallelepiped shaped treatment chamber 102, which is closed on the upper part by a vaulted cover 103 (Fig. 1).
The treatment chamber 102, at one end includes a loading hopper 110 to load the material to be treated, while at the opposite end it includes an exit opening 120 to discharge the treated material. Between said hopper 110 and exit opening 1 20 a linear path develops for the material to be treated, which continues downwards from upstream with respect to the treatment chamber 102, until it crosses the exit opening 120 to be discharged. Inside the treatment chamber 102 some cradle modules 130a, 130b, 130c and 130d are present, which can be implemented in any number, and which are transversely oriented with respect to the linear path of the material to be treated and each of which is configured with a cradle shaped cross section, the one contiguous and parallel with respect to the other one. Within each cradle module 1 30a, 1 30b, 130c and 1 30d two longitudinal, parallel and radially intersecting tilters 140, 141 are present, which are moved by electro-mechanic means 142 which are external means with respect to said treatment chamber 102. A separating plate 150 of the type which is adjustable in height, divides each cradle module 1 30a, 1 30b, 130c and 130d from the adjacent one, in such a way as to determine the height of the board over which the material to be treated overflows during the processing phase continuing along said linear path from upstream to downstream. In the immediately underlying part of each cradle module 130a, 1 30b, 1 30c and 130d (Fig. 2) a fluidification bottom 1 60 is present of the sintered or porous type, e.g. the one called Visco-Screen, and through which the airflow flows coming from the plenum air chamber 170 which is underlying with respect to said fluidification bottom 160. In the part over the treatment chamber 102, a closing vault 103 is present, in correspondence of which aligned magnetron 180 are externally located, in such a way as to drive the respective microwaves bundle towards the inside of the treatment chamber 102 and in particular toward the underlying cradle modules 130a, 130b, 130c and 130d.
In figure 3, the typical scheme of a plant is represented for treating bulk materials, which includes at least one modular apparatus 10. More in detail, said plant includes a network-cogenerator 20, a first suction device 30 for the external air entry, a heat exchanger 40, and a second air suction device 50, providing the recirculation of the air introduced inside the treatment chamber 102, of the modular apparatus 10. More in detail, the network-cogenerator 20 supplies the heat exchanger 40, in correspondence of which by means of the first suction device 30 external air is introduced which is then brought to and maintained at the desired temperature by the same, to be successively introduced in the plenum air chamber 170 and therefore dispersed inside the treatment chamber 102, first passing across the fluidification bottom 160 in correspondence with each cradle module 130a, 130b, 130c and 130d. The air, inside the treatment chamber 102, during the treatment cycle, is therefore again sucked, and, by means of the second air suction device 50, again supplied to the heat exchanger 40, to be again brought to the desired temperature and introduced again to circulate.
A logical unit provides the management of the apparatus 10. More in detail, sensor means detect the temperature even in more than one point at least inside the treatment chamber 102, and cooperate with second sensor means which are present in the heat exchanger. Said logical unit also controls at least the temperature of the flow which is introduced into the treatment chamber 102, the speed and therefore the rate of the air flow which is introduced into the plenum air chamber 170, as well as the speed of the tilters 140, 141. Still the logical unit can also control the height of the separating plates 150 between each cradle module 1 30a, 130b, 1 30c and 130d, even if in any case said adjustment can be made manually, depending on the specific requirements.
Operatively, the process provides the modular apparatus 10 to be charged, introducing a determined quantity of bulk material inside the hopper 110. Said bulk material occupies the first cradle module 130a in such a way as to be subject to a fluctuation due to the shaking effect of the tilters 140, 141 and of the airflow coming from the fluidification bottom 1 60, and at the same time in such a way as to be invested by the microwaves bundle generated by the magnetron 180. The exceeding material which fluctuates inside the first cradle module 1 30a proceeds along the path towards downstream, and it overflows over the board of the separating plate 150, in such a way as to progressively fill the module 1 30b wherein it is subject to a second fluctuation and so on for the cradle modules 130c and 130d until exiting through the exit opening 120 discharging the treated material.

Reference

10 modular apparatus
1 00 frame
101 support legs
102 treatment chamber
103 vaulted cover
110 loading hopper
1 20 exit opening to discharge the treated material
130a, 130b, 130c and 130d cradle-modules
140, 141 tilters
142 electro mechanic means
150 separating plate
160 fluidification bottom
170 plenum air chamber
180 magnetron
20 network-co-generator
30 first suction device
40 heat exchanger
50 second air suction device

Claims

Multi-purpose modular apparatus for fast and continuous drying and dehumidification of bulk materials and process with a plant for drying, dehumidifying bulk materials, said modular apparatus 10 comprising at least one treatment chamber 102 of the bulk materials, with:
(a) a multiple processing stage linear path developing on a horizontal plane, comprising an upstream entry 120 and a downstream discharging exit 1 30 of the bulk material;

(b) microwaves generators 180 located along said linear path and orientated in such a way as to direct the microwaves bundle inside said treatment chamber 102;

(c) means generating a controlled hot air flow, which is introduced into said treatment chamber 102 of the bulk materials, wherein said controlled hot air flow passes through the fluidification bottom 1 60 which is obtained along and at the base of said multiple stage linear path;
characterised in that said treatment chamber 102 includes adjacent container modules 130a, 130b, 130c and 130d along said linear path, which are transversally placed with respect to said linear path, wherein each container module 130a, 130b, 130c and 130d comprises at least one tilter device 140, 141 and it is separated from the other one by a separating plate 150 which is adjustable in height so that said bulk material overflows over the respective top edge of the separating plate 150 and it flows down in the adjacent and transverse container module.
Multi-purpose modular apparatus for drying, according to claim 1, characterised in that each transverse container module 1 30a, 1 30b, 130c and 1 30d has a cradle shaped cross section.
Multi-purpose modular apparatus for drying, according to claim 1 and 2, characterised in that it is controlled by a logical unit, said logical unit detecting the temperature even in more than one point at least inside the treatment chamber 102 by means of sensor means, and cooperating with second sensor means which are present in the heat exchanger; said logical unit at least controls the temperature of the flow which is introduced into the treatment chamber 102, the speed of the air flow which is introduced into the plenum air chamber 170, as well as the speed of the tilters 140, 141 and furthermore in which still said logical unit controls the height of the separating plates 150 between each cradle module 130a, 130b, 130c and 130d.
Drying and dehumidification process of bulk materials using the apparatus 10, according to claims 1 and 2 which provides the modular apparatus 10 to be charged, introducing a determined quantity of bulk material inside the hopper 110; said bulk material occupies the first cradle module 130a in such a way as to be subject to a fluctuation due to the shaking effect of the tilters 140, 141 and of the airflow coming from the fluidification bottom 160, and at the same time in such a way as to be invested by the microwaves bundle generated by the magnetron 180, and in which the exceeding material which fluctuates inside the first cradle module 130a proceeds along the path towards downstream, and it overflows over the board of the separating plate 1 50, in such a way as to progressively fill the module 1 30b wherein it is subject to a second fluctuation and so on for the cradle modules 130c and 1 30d until exiting through the exit opening 120 discharging the treated material.
Plant for treating bulk materials including at least one modular apparatus 10 according to any of Claims 1-3, characterised in that it includes a network-cogenerator 20, a first suction device 30 for the external air entry, a heat exchanger 40, and a second air suction device 50, providing the recirculation of the air introduced inside the treatment chamber 102, of the modular apparatus 10, wherein said network-cogenerator 20, supplies the heat exchanger 40, in correspondence of which by means of the first suction device 30 external air is introduced which is then brought to and maintained at the desired temperature by the same, to be successively introduced in the plenum air chamber 170 and therefore dispersed inside the treatment chamber 102 of the modular apparatus 10 first passing across the fluidification bottom 1 60 in correspondence with each cradle module 130a, 1 30b, 130c and 1 30d, and wherein the air, inside the treatment chamber 102, during the treatment cycle, is therefore again sucked, and, by means of the second air suction device 50, again supplied to the heat exchanger 40, to be again brought to the desired temperature and introduced again to circulate.