EP1407206A2 - Dryer for cereals and granular materials in general - Google Patents

Dryer for cereals and granular materials in general

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Publication number
EP1407206A2
EP1407206A2 EP02762321A EP02762321A EP1407206A2 EP 1407206 A2 EP1407206 A2 EP 1407206A2 EP 02762321 A EP02762321 A EP 02762321A EP 02762321 A EP02762321 A EP 02762321A EP 1407206 A2 EP1407206 A2 EP 1407206A2
Authority
EP
European Patent Office
Prior art keywords
chamber
dryer according
drying
flow
air
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP02762321A
Other languages
German (de)
French (fr)
Other versions
EP1407206B1 (en
Inventor
Silvano Barbieri
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Agrex SpA
Original Assignee
Agrex SpA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Agrex SpA filed Critical Agrex SpA
Publication of EP1407206A2 publication Critical patent/EP1407206A2/en
Application granted granted Critical
Publication of EP1407206B1 publication Critical patent/EP1407206B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
    • F26B21/001—Drying-air generating units, e.g. movable, independent of drying enclosure
    • F26B21/002—Drying-air generating units, e.g. movable, independent of drying enclosure heating the drying air indirectly, i.e. using a heat exchanger
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B17/00—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement
    • F26B17/12—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed solely by gravity, i.e. the material moving through a substantially vertical drying enclosure, e.g. shaft
    • F26B17/14—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed solely by gravity, i.e. the material moving through a substantially vertical drying enclosure, e.g. shaft the materials moving through a counter-current of gas
    • F26B17/1408—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed solely by gravity, i.e. the material moving through a substantially vertical drying enclosure, e.g. shaft the materials moving through a counter-current of gas the gas being supplied and optionally extracted through ducts extending into the moving stack of material
    • F26B17/1425—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed solely by gravity, i.e. the material moving through a substantially vertical drying enclosure, e.g. shaft the materials moving through a counter-current of gas the gas being supplied and optionally extracted through ducts extending into the moving stack of material the ducts being perforated and arranged vertically
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B9/00—Machines or apparatus for drying solid materials or objects at rest or with only local agitation; Domestic airing cupboards
    • F26B9/06—Machines or apparatus for drying solid materials or objects at rest or with only local agitation; Domestic airing cupboards in stationary drums or chambers
    • F26B9/08—Machines or apparatus for drying solid materials or objects at rest or with only local agitation; Domestic airing cupboards in stationary drums or chambers including agitating devices, e.g. pneumatic recirculation arrangements
    • F26B9/082—Machines or apparatus for drying solid materials or objects at rest or with only local agitation; Domestic airing cupboards in stationary drums or chambers including agitating devices, e.g. pneumatic recirculation arrangements mechanically agitating or recirculating the material being dried
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B9/00—Machines or apparatus for drying solid materials or objects at rest or with only local agitation; Domestic airing cupboards
    • F26B9/10—Machines or apparatus for drying solid materials or objects at rest or with only local agitation; Domestic airing cupboards in the open air; in pans or tables in rooms; Drying stacks of loose material on floors which may be covered, e.g. by a roof
    • F26B9/103—Machines or apparatus for drying solid materials or objects at rest or with only local agitation; Domestic airing cupboards in the open air; in pans or tables in rooms; Drying stacks of loose material on floors which may be covered, e.g. by a roof using fixed or removable drying air channels placed in the stack, e.g. horizontally or vertically

Definitions

  • the present invention relates to a dryer for cereals and granular materials in general according to the preamble of the main claim No. 1.
  • the present invention finds a particular, although not exclusive, application in the field of mobile dryers, or rather those dryers which are stationed close to the cereal harvesting areas in order to dry the cereals on site and in a short time so as to avoid degradation thereof due principally to the moisture contained in the harvested cereal.
  • Dryers of the type indicated typically comprise a vertical cylindrical drying chamber adapted to contain the harvested cereal, and a heating unit including a burner associated with a combustion chamber for the production of hot air to be introduced inside the drying chamber for the purpose of facilitating the evaporation of the moisture contained in the cereal being dried.
  • a fan is conventionally provided for introducing the flow of air into the drying chamber in a central cavity separated from the stored cereal, for example by means of panels with perforated surface. From this central cavity the flow of hot air generated and mixed with the combustion gases is caused to penetrate into the layers of cereal present in the drying chamber, promoting the aforesaid drying process.
  • the drying air is therefore heated at the combustion chamber, in order then to be conveyed inside the central cavity of the drying chamber. Moreover, the flow of air heated by the heating unit is introduced into the cavity mixed with the combustion gases which therefore come into contact»with the cereal in the drying process.
  • Another type of dryer provides for the use of a heat exchanger placed externally of the dryer, by means of which the flow of air is heated which is then conveyed inside the drying chamber.
  • a principal aim of the present invention is that of providing a dryer for cereals or similar materials, of an improved type capable of maximising the efficiency in the thermal exchange between the heat generated by the heating unit and that transferred to the flow of air responsible for the drying process, improving the overall output thereof.
  • Another aim is to produce a dryer which makes it possible to keep the flow of drying hot air separate from the combustion gases, preventing contact of the latter with the cereal, so safeguarding the characteristics of the cereal itself.
  • Yet another aim is to produce a dryer which improves the overall efficiency of the thermal exchange in order to obtain in fast times a high and homogenous degree of drying of the mass of cereal to be dried.
  • Figure 1 is a perspective view in partial section of a dryer produced according to the invention
  • Figure 2 is a perspective view in partial section of a detail of the dryer of Figure 1 ,
  • Figure 3 is a perspective exploded view in partial section of the detail of Figure 2
  • Figure 4 is a perspective view in partial section of a detail of Figure 3.
  • the dryer 1 comprises a drying chamber, indicated as a whole by 2, which consists of an upper main part 2a of cylindrical shape, and of a frustoconical lower hopper part 2b which ends in a delivery mouth 3 bearing a plate-type shutter with adjustable opening for partialising the quantity of cereal discharged.
  • the drying chamber 2 is mounted on a frame 4 with wheels 5 so that the dryer is mobile and transportable onto the cereal harvesting site where drying takes place.
  • Conveyor devices preferably screw conveyors, are further provided for the functions of loading/unloading and also recirculating the cereal inside the drying chamber. More particularly, a horizontal screw conveyor 6 is provided, placed below the delivery mouth 3 and connected to a vertical screw conveyor 7.
  • the latter extends parallel to the vertical central axis X of the drying chamber 2, from the lower base of the chamber to the apex thereof, where there is disposed an inclined discharge pipe 8 by means of which the material which ascends from the vertical conveyor 7 can drop down again inside the chamber 2 or to the outside, in the discharge (emptying) phase of the dryer.
  • a third screw conveyor 9 is provided for transferring the cereal at the point of connection of the conveyors 6 and 7.
  • the section of horizontal conveyor 6 extending between the delivery mouth 3 and the connection with the vertical conveyor 7 is further arranged to convey the material delivered by the mouth 3 and to transfer it, through the vertical screw 7 back inside the drying chamber to guarantee the recirculation of the cereal during the drying phase.
  • the dryer 1 also comprises a heating unit 10 including a burner 11 associated with a combustion chamber 12 for heating a flow of air to be introduced into the drying chamber 2, as will appear more clearly in the continuation of the description, in order to promote drying of the cereal.
  • a flow of air is generated by a fan 13 and is conveyed, through a duct 14, into the drying chamber and, more particularly, into a central cavity 15 of the chamber bounded by a bell 16 with perforated surface, for example formed by panelling 17 of perforated sheet metal adapted to keep the cavity separate from the cereal, but at the same time permitting the passage of the flow of air from the cavity in the direction of the layers of cereal stored in the dryer.
  • Said central cavity 15 is coaxial with the drying chamber so that said bell 16 is surrounded by the cereal loaded into the drying chamber.
  • the combustion chamber 12 is mounted internally of the duct 14, coaxially therewith, and is extended as far as the inside of the central cavity 15 where it communicates with a further chamber 18 constituting a heat exchange device for heating the flow of drying air, as described in greater detail hereinafter.
  • Said chamber 18 is bounded by a lateral wall 19a closed by opposed end walls 19b, 19c, all the walls defining respective surfaces for thermal exchange between the combustion gases conveyed inside the chamber 18 and the flow of drying air, generated by the fan, which flows along the outside of said walls.
  • the chamber 18 is produced so as to be sealed against the escape of the flue gases and their possible introduction into the drying chamber.
  • the chamber 18 is provided with an inlet aperture 20 for the flue gases, communicating with the combustion chamber, and also with a plurality of outlet apertures 21 for the flue gases, connected to conveying means for the flue gases to transfer them to the outside of the drying chamber.
  • Said conveying means comprise a plurality of tubular ducts 22 communicating at an axial end thereof with the chamber 18, and at the opposite end with a common manifold 23, connected in its turn to a flue gas discharge chimney, indicated by 24.
  • the ducts 22 are extended in a bundle around the combustion chamber 12 and are housed internally of the duct 14 so as to be assailed in a counterflow by the flow of air generated by the fan and directed into the drying chamber. The result is thus a further thermal exchange between the flue gases conveyed outside by the ducts 22 and the flow of drying air induced by the fan for pre-heating of said flow of air, exploiting the heat of the combustion gases directed to the discharge chimney.
  • the latter is provided with further finned surfaces consisting, for example, of suitably shaped plate-like members 25 fixed to the lateral wall 19a so as to define passages for channelling the flow of drying air with an increase in the thermal exchange surface flowed over.
  • Tubular members are further provided, all indicated by 26, passing inside the chamber 18 and open at the opposed ends and also suitably secured to the lateral wall 19a, which are intended to be assailed by the hot combustion gases inside the chamber 18 to induce a thermal exchange between said gases and the flow of drying air conveyed in said tubular members for a further transfer of heat to the flow of air.
  • the chamber 18 has an approximately annular configuration comprising a central cylindrical opening 27 coaxial with the axis X, suitable for permitting the passage of a central shaft 28 for the actuation of mixing means 29 for mixing the cereal.
  • the cylindrical opening 27 is selected to be of such dimensions and shape as to allow the positioning of the conveyor.
  • the chamber 18 may alternatively be devoid of a central through opening or provide a reduced opening for the passage of transmission devices such as for example the aforesaid shaft 28.
  • the surface of the cylindrical opening is also conveniently provided with further fins 30, for example in the form of profiles extending axially at a predetermined angular pitch, and adapted to increase the thermal exchange surface.
  • the lateral wall 19a of the chamber 18 is further provided with an indentation 31 defining, within the chamber itself, a pair of deflector surfaces
  • Each duct 22 of the tube bundle which envelopes the combustion chamber 12 is further provided on the inside with a respective helical body 33, coaxial therewith.
  • a respective helical body 33 is in the shape of a double helix or rather is formed by a pair of superposed and angularly spaced helices which define, in each duct 22, a flow channel with a double-helical course in which the combustion gases are conveyed.
  • the path travelled by the flue gases is much greater than the axial length of the duct and the flue gases are in contact more with the outer wall of the tubes, owing to the presence of the helical channel, and consequently there is a larger amount of heat transferred from the flue gases to the flow of air in counterflow, at a velocity and pressure kept substantially constant, thereby increasing the thermal exchange without any increase in the axial development of the tube bundle.
  • the invention thus fulfils the aims proposed by obtaining numerous advantages with respect to the known solutions.
  • a principal advantage is that with the dryer according to the invention the efficiency of the thermal exchange in the heating of the drying air is increased, owing to the fact that the combustion and also the combustion gases are brought directly inside the drying chamber and collected in a chamber constituting a heat exchanger in which the thermal exchange is maximised. Tests conducted by the Applicant have shown a greater efficiency in the overall thermal exchange with respect to the known solutions.
  • a further advantage is that the heat of the hot combustion gases directed to the discharge chimney is effectively transferred to the flow of drying air for pre-heating of the flow itself, benefitting from a thermal exchange in counterflow.
  • a further advantage is that according to the invention the combustion gases are kept separate from the flow of drying air inside the drying chamber so as to avoid contact between the flue gases and combustion products and the cereal, preserving the characteristics and properties of the latter.
  • a still further advantage is that the efficiency of the thermal exchange in counterflow between the flue gases conveyed in the bundle of discharge ducts and the flow of air generated by the fan is increased owing to the helical flow channels provided within the ducts, which also make it possible to limit advantageously the overall axial dimensions of the tube bundle, reducing the overall size of the dryer.
  • a further advantage is that the application of the exchanger does not involve structural and dimensional changes to the dryer, thus allowing its application to existing machines, and also the containment of the production costs. Moreover, the overall dimensions do not change, thus keeping the transport costs unaltered.

Abstract

A dryer for cereals and granular materials in general is described, comprising a drying chamber (2) adapted to contain the cereal to be dried, a heating unit (10) including a burner (11) associated with a combustion chamber (12) for heating a flow of air introduced into said drying chamber (2) for drying the cereal, and also a further chamber (18) disposed within the drying chamber (2) so as to be surrounded by the mass of cereal to be dried. This chamber (18) extends in prolongation of and in communication with the combustion chamber (12) of the heating unit so as to constitute a heat exchange device for heating the drying air.

Description

Dryer for cereals and granular materials in general. TECHNICAL FIELD
The present invention relates to a dryer for cereals and granular materials in general according to the preamble of the main claim No. 1. TECHNOLOGICAL BACKGROUND
The present invention finds a particular, although not exclusive, application in the field of mobile dryers, or rather those dryers which are stationed close to the cereal harvesting areas in order to dry the cereals on site and in a short time so as to avoid degradation thereof due principally to the moisture contained in the harvested cereal.
Dryers of the type indicated typically comprise a vertical cylindrical drying chamber adapted to contain the harvested cereal, and a heating unit including a burner associated with a combustion chamber for the production of hot air to be introduced inside the drying chamber for the purpose of facilitating the evaporation of the moisture contained in the cereal being dried. A fan is conventionally provided for introducing the flow of air into the drying chamber in a central cavity separated from the stored cereal, for example by means of panels with perforated surface. From this central cavity the flow of hot air generated and mixed with the combustion gases is caused to penetrate into the layers of cereal present in the drying chamber, promoting the aforesaid drying process.
According to this type of dryer, the drying air is therefore heated at the combustion chamber, in order then to be conveyed inside the central cavity of the drying chamber. Moreover, the flow of air heated by the heating unit is introduced into the cavity mixed with the combustion gases which therefore come into contact»with the cereal in the drying process.
Another type of dryer provides for the use of a heat exchanger placed externally of the dryer, by means of which the flow of air is heated which is then conveyed inside the drying chamber. DESCRIPTION OF THE INVENTION
A principal aim of the present invention is that of providing a dryer for cereals or similar materials, of an improved type capable of maximising the efficiency in the thermal exchange between the heat generated by the heating unit and that transferred to the flow of air responsible for the drying process, improving the overall output thereof.
Another aim is to produce a dryer which makes it possible to keep the flow of drying hot air separate from the combustion gases, preventing contact of the latter with the cereal, so safeguarding the characteristics of the cereal itself.
Yet another aim is to produce a dryer which improves the overall efficiency of the thermal exchange in order to obtain in fast times a high and homogenous degree of drying of the mass of cereal to be dried.
These and other aims which will become clear hereinafter are fulfilled, in accordance with the present invention, by a dryer having the characteristics described in the claims which follow. BRIEF DESCRIPTION OF THE DRAWINGS The characteristics and advantages of the invention will become clearer from the following detailed description of one of its preferred embodiments, supplied with reference to the appended drawings, provided by way of non-limiting example, wherein:
Figure 1 is a perspective view in partial section of a dryer produced according to the invention,
Figure 2 is a perspective view in partial section of a detail of the dryer of Figure 1 ,
Figure 3 is a perspective exploded view in partial section of the detail of Figure 2, Figure 4 is a perspective view in partial section of a detail of Figure 3.
PREFERRED EMBODIMENT OF THE INVENTION
With initial reference to Figure 1 , there is indicated as a whole by 1 a mobile dryer for cereals and other granular materials, produced in accordance with the present invention. The dryer 1 comprises a drying chamber, indicated as a whole by 2, which consists of an upper main part 2a of cylindrical shape, and of a frustoconical lower hopper part 2b which ends in a delivery mouth 3 bearing a plate-type shutter with adjustable opening for partialising the quantity of cereal discharged.
The drying chamber 2 is mounted on a frame 4 with wheels 5 so that the dryer is mobile and transportable onto the cereal harvesting site where drying takes place.
Conveyor devices, preferably screw conveyors, are further provided for the functions of loading/unloading and also recirculating the cereal inside the drying chamber. More particularly, a horizontal screw conveyor 6 is provided, placed below the delivery mouth 3 and connected to a vertical screw conveyor 7.
The latter extends parallel to the vertical central axis X of the drying chamber 2, from the lower base of the chamber to the apex thereof, where there is disposed an inclined discharge pipe 8 by means of which the material which ascends from the vertical conveyor 7 can drop down again inside the chamber 2 or to the outside, in the discharge (emptying) phase of the dryer. A third screw conveyor 9 is provided for transferring the cereal at the point of connection of the conveyors 6 and 7.
The section of horizontal conveyor 6 extending between the delivery mouth 3 and the connection with the vertical conveyor 7 is further arranged to convey the material delivered by the mouth 3 and to transfer it, through the vertical screw 7 back inside the drying chamber to guarantee the recirculation of the cereal during the drying phase.
The dryer 1 also comprises a heating unit 10 including a burner 11 associated with a combustion chamber 12 for heating a flow of air to be introduced into the drying chamber 2, as will appear more clearly in the continuation of the description, in order to promote drying of the cereal. Such a flow of air is generated by a fan 13 and is conveyed, through a duct 14, into the drying chamber and, more particularly, into a central cavity 15 of the chamber bounded by a bell 16 with perforated surface, for example formed by panelling 17 of perforated sheet metal adapted to keep the cavity separate from the cereal, but at the same time permitting the passage of the flow of air from the cavity in the direction of the layers of cereal stored in the dryer. Said central cavity 15 is coaxial with the drying chamber so that said bell 16 is surrounded by the cereal loaded into the drying chamber.
The combustion chamber 12 is mounted internally of the duct 14, coaxially therewith, and is extended as far as the inside of the central cavity 15 where it communicates with a further chamber 18 constituting a heat exchange device for heating the flow of drying air, as described in greater detail hereinafter. Said chamber 18 is bounded by a lateral wall 19a closed by opposed end walls 19b, 19c, all the walls defining respective surfaces for thermal exchange between the combustion gases conveyed inside the chamber 18 and the flow of drying air, generated by the fan, which flows along the outside of said walls.
It should be noted that the chamber 18 is produced so as to be sealed against the escape of the flue gases and their possible introduction into the drying chamber. To this end, the chamber 18 is provided with an inlet aperture 20 for the flue gases, communicating with the combustion chamber, and also with a plurality of outlet apertures 21 for the flue gases, connected to conveying means for the flue gases to transfer them to the outside of the drying chamber. Said conveying means comprise a plurality of tubular ducts 22 communicating at an axial end thereof with the chamber 18, and at the opposite end with a common manifold 23, connected in its turn to a flue gas discharge chimney, indicated by 24.
According to a preferred configuration, the ducts 22 are extended in a bundle around the combustion chamber 12 and are housed internally of the duct 14 so as to be assailed in a counterflow by the flow of air generated by the fan and directed into the drying chamber. The result is thus a further thermal exchange between the flue gases conveyed outside by the ducts 22 and the flow of drying air induced by the fan for pre-heating of said flow of air, exploiting the heat of the combustion gases directed to the discharge chimney. For the purpose of increasing the thermal exchange principally by heat convection at the chamber 18, the latter is provided with further finned surfaces consisting, for example, of suitably shaped plate-like members 25 fixed to the lateral wall 19a so as to define passages for channelling the flow of drying air with an increase in the thermal exchange surface flowed over.
Tubular members are further provided, all indicated by 26, passing inside the chamber 18 and open at the opposed ends and also suitably secured to the lateral wall 19a, which are intended to be assailed by the hot combustion gases inside the chamber 18 to induce a thermal exchange between said gases and the flow of drying air conveyed in said tubular members for a further transfer of heat to the flow of air.
It should be observed that in the example described the chamber 18 has an approximately annular configuration comprising a central cylindrical opening 27 coaxial with the axis X, suitable for permitting the passage of a central shaft 28 for the actuation of mixing means 29 for mixing the cereal. It is understood that, if the dryer is provided with a central vertical conveyor of axis X, the cylindrical opening 27 is selected to be of such dimensions and shape as to allow the positioning of the conveyor. In dryers with vertical conveyor external to the drying chamber, such as that of the example described, the chamber 18 may alternatively be devoid of a central through opening or provide a reduced opening for the passage of transmission devices such as for example the aforesaid shaft 28. In the latter case, the surface of the cylindrical opening is also conveniently provided with further fins 30, for example in the form of profiles extending axially at a predetermined angular pitch, and adapted to increase the thermal exchange surface.
The lateral wall 19a of the chamber 18 is further provided with an indentation 31 defining, within the chamber itself, a pair of deflector surfaces
32a, 32b adapted to deflect the flow of hot flue gases introduced into the chamber, inducing internal circulatory motions to facilitate the transfer of heat to the walls of the chamber itself, maximising the relative thermal exchange.
Each duct 22 of the tube bundle which envelopes the combustion chamber 12 is further provided on the inside with a respective helical body 33, coaxial therewith. Preferably, such a body is in the shape of a double helix or rather is formed by a pair of superposed and angularly spaced helices which define, in each duct 22, a flow channel with a double-helical course in which the combustion gases are conveyed. The result is that the path travelled by the flue gases is much greater than the axial length of the duct and the flue gases are in contact more with the outer wall of the tubes, owing to the presence of the helical channel, and consequently there is a larger amount of heat transferred from the flue gases to the flow of air in counterflow, at a velocity and pressure kept substantially constant, thereby increasing the thermal exchange without any increase in the axial development of the tube bundle. Provision is also made for the helical bodies 33 to be axially slidable in the corresponding ducts 22 and for this purpose they are provided with a respective manipulation handle 34 provided at the axial end of the body 33 facing towards the flue gas discharge manifold 23. In the manifold a ring of openings 35 coaxial with the tube bundle 22 is provided to permit the extraction and insertion of the helical bodies 33 from and into the respective ducts of the bundle.
The invention thus fulfils the aims proposed by obtaining numerous advantages with respect to the known solutions.
A principal advantage is that with the dryer according to the invention the efficiency of the thermal exchange in the heating of the drying air is increased, owing to the fact that the combustion and also the combustion gases are brought directly inside the drying chamber and collected in a chamber constituting a heat exchanger in which the thermal exchange is maximised. Tests conducted by the Applicant have shown a greater efficiency in the overall thermal exchange with respect to the known solutions.
A further advantage is that the heat of the hot combustion gases directed to the discharge chimney is effectively transferred to the flow of drying air for pre-heating of the flow itself, benefitting from a thermal exchange in counterflow. A further advantage is that according to the invention the combustion gases are kept separate from the flow of drying air inside the drying chamber so as to avoid contact between the flue gases and combustion products and the cereal, preserving the characteristics and properties of the latter.
A still further advantage is that the efficiency of the thermal exchange in counterflow between the flue gases conveyed in the bundle of discharge ducts and the flow of air generated by the fan is increased owing to the helical flow channels provided within the ducts, which also make it possible to limit advantageously the overall axial dimensions of the tube bundle, reducing the overall size of the dryer.
A further advantage is that the application of the exchanger does not involve structural and dimensional changes to the dryer, thus allowing its application to existing machines, and also the containment of the production costs. Moreover, the overall dimensions do not change, thus keeping the transport costs unaltered.

Claims

C L A I M S
1. A dryer for cereals and granular materials in general, comprising: - a drying chamber (2) adapted to contain the cereal to be dried, a heating unit (10) including a burner (11 ) associated with a combustion chamber (12) for heating a flow of air to be introduced into said drying chamber (2) for drying the cereal, characterised in that it comprises a further chamber (18) disposed within the drying chamber (2) so as to be surrounded by the mass of cereal to be dried, said chamber (18) extending in prolongation of and in communication with the combustion chamber (12) of the heating unit (10), in such a manner as to constitute a heat exchange device for heating the drying air.
2. A dryer according to claim 1 , wherein the chamber (18) constituting said heat exchange device is coaxial with the drying chamber (2).
3. A dryer according to claim 1 or 2, wherein said chamber (18) is bounded by walls (19a, 19b, 19c) defining surfaces for thermal exchange between the combustion gases conveyed inside said chamber (18) and the flow of drying air which flows along the outside of said surfaces (19a, 19b, 19c).
4. A dryer according to claim 3, wherein said walls are provided with further finned surfaces (25) adapted to increase the thermal exchange in said exchange device.
5. A dryer according to one or more of the preceding claims, wherein tubular members (26) are provided, passing inside said chamber (18) and capable of being assailed by the combustion gases so as to induce a thermal exchange between said gases and the flow of drying air conveyed in said tubular members (26) for heating said air.
6. A dryer according to one or more of the preceding claims, wherein the chamber (18) constituting said heat exchanger is produced so as to be sealed against the introduction of the combustion gases into the drying chamber (2).
7. A dryer according to one or more of the preceding claims, wherein the chamber (18) constituting said exchanger comprises a first, inlet opening (20) for the flue gases, communicating directly with the combustion chamber (12), and at least one second, outlet opening (21) for the flue gases, communicating with means (22) for conveying said flue gases to the outside of the drying chamber (2).
8. A dryer according to claim 7, wherein said conveying means comprises at least one tubular duct (22) having opposed ends communicating with said chamber (18) constituting the heat exchanger and with a flue gas discharge chimney (24).
9. A dryer according to claim 8, wherein a plurality of said tubular ducts (22) is provided for conveying the flue gases into said chimney (24), outside the drying chamber (2).
10. A dryer according to claim 9, wherein said ducts (22) extend in a bundle around the combustion chamber (12) and are connected to a manifold device (23) communicating with the flue gas discharge chimney (24).
11. A dryer according to claim 10, wherein said bundle of ducts (22) is disposed in a position such as to be assailed in counterflow by a flow of air generated by fan means, for a thermal exchange between said flue gases and said flow of air so as to pre-heat the flow of air introduced into said drying chamber (2).
12. A dryer according to one of claims 8 to 11 , wherein means are provided for extending the path travelled by the flue gases in each of the ducts (22) of said bundle so as to increase the thermal exchange between said flue gases and the flow of air sent by said fan means in a counterflow to said combustion gases.
13. A dryer according to claim 12, wherein said means comprise a respective helical body (33) housed coaxially in each of said ducts so as to define a flow channel with helical course along the axial development of said ducts (22).
14. A dryer according to claim 13, wherein each of said helical bodies (33) is removably mounted in the respective duct (22).
15. A dryer according to claim 13 or 14, wherein each of said helical bodies (33) is axially slidable in the respective duct (22).
16. A dryer according to one of claims 13 to 15, wherein each of said helical bodies (33) is provided with a respective manipulation handle (34) extended from the end of said body (33) facing towards the discharge chimney (24) for the combustion gases.
EP02762321A 2001-07-18 2002-07-04 Dryer for cereals and granular materials in general Expired - Lifetime EP1407206B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
IT2001PD000181A ITPD20010181A1 (en) 2001-07-18 2001-07-18 DRIER FOR CEREALS AND GRANULAR MATERIALS IN GENERAL.
ITPD20010181 2001-07-18
PCT/EP2002/007426 WO2003008887A2 (en) 2001-07-18 2002-07-04 Dryer for cereals and granular materials in general

Publications (2)

Publication Number Publication Date
EP1407206A2 true EP1407206A2 (en) 2004-04-14
EP1407206B1 EP1407206B1 (en) 2006-06-28

Family

ID=11452420

Family Applications (1)

Application Number Title Priority Date Filing Date
EP02762321A Expired - Lifetime EP1407206B1 (en) 2001-07-18 2002-07-04 Dryer for cereals and granular materials in general

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WO2018211423A1 (en) * 2017-05-16 2018-11-22 Agrex Spa Heat exchanger, heat generator and equipment for drying bulk products

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UA80683C2 (en) 2007-10-25
PL200040B1 (en) 2008-11-28
DE60212845D1 (en) 2006-08-10
EP1407206B1 (en) 2006-06-28
RU2004104640A (en) 2005-05-10
WO2003008887A3 (en) 2003-09-04
ITPD20010181A1 (en) 2003-01-18
ATE331924T1 (en) 2006-07-15
AU2002328314A1 (en) 2003-03-03
RU2295682C2 (en) 2007-03-20
WO2003008887A2 (en) 2003-01-30
PL366843A1 (en) 2005-02-07

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