Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F26—DRYING
  • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
  • F26B3/00—Drying solid materials or objects by processes involving the application of heat
  • F26B3/28—Drying solid materials or objects by processes involving the application of heat by radiation, e.g. from the sun
  • F26B3/30—Drying solid materials or objects by processes involving the application of heat by radiation, e.g. from the sun from infrared-emitting elements
  • F26B3/305—Drying solid materials or objects by processes involving the application of heat by radiation, e.g. from the sun from infrared-emitting elements the infrared radiation being generated by combustion or combustion gases
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
  • F23C3/00—Combustion apparatus characterised by the shape of the combustion chamber
  • F23C3/002—Combustion apparatus characterised by the shape of the combustion chamber the chamber having an elongated tubular form, e.g. for a radiant tube
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F26—DRYING
  • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
  • F26B15/00—Machines or apparatus for drying objects with progressive movement; Machines or apparatus with progressive movement for drying batches of material in compact form
  • F26B15/10—Machines or apparatus for drying objects with progressive movement; Machines or apparatus with progressive movement for drying batches of material in compact form with movement in a path composed of one or more straight lines, e.g. compound, the movement being in alternate horizontal and vertical directions
  • F26B15/12—Machines or apparatus for drying objects with progressive movement; Machines or apparatus with progressive movement for drying batches of material in compact form with movement in a path composed of one or more straight lines, e.g. compound, the movement being in alternate horizontal and vertical directions the lines being all horizontal or slightly inclined
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
  • F27B17/00—Furnaces of a kind not covered by any preceding group
  • F27B17/0016—Chamber type furnaces
  • F27B17/0041—Chamber type furnaces specially adapted for burning bricks or pottery
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
  • F27D99/00—Subject matter not provided for in other groups of this subclass
  • F27D99/0001—Heating elements or systems
  • F27D99/0033—Heating elements or systems using burners

Definitions

• the present invention relates to an apparatus for thermal treatment of manufactured articles, particularly made of ceramic material.
• the processing of manufactured articles such as tiles, sanitary fixtures and bricks provides for the execution of various steps in a heated and controlled environment, such as in particular drying and firing.
• the drying step consists in keeping the ceramic articles that have already been shaped in a heated environment for the time needed to achieve the at least partial evaporation of the water fraction contained in them.
• Known drying kilns generally consist of a controlled-temperature chamber into which a stream of hot and dry air is introduced which strikes the articles to be dried, transferring heat to them, substantially by convection, and cold and moist air is extracted from such drying kilns. These drying kilns can operate continuously or discontinuously.
• the heated chamber is shaped like a tunnel and is crossed by the articles, which are loaded onto suitable conveyors from the inlet toward the outlet; in the second case, the heated chamber is instead provided with a single opening for introducing and removing the articles, which are kept stationary during the treatment.
• the firing step consists in a further heating of the articles that have already been dried, so as to achieve complete evaporation of the water contained therein and the necessary physical transformations, which make the mix and any coating acquire the properties that are required of the finished ceramic product.
• Kilns used for firing substantially consist of a heated chamber, which can have a single opening (discontinuous kilns) or can be tunnel-shaped (continuous kilns).
• these apparatuses use burners which substantially consist of a manifold body which is connected to a unit for feeding in a gaseous fuel, which exits from a combustion head at which there are one or more electrodes for generating and controlling the flame, and to a unit for feeding in a gaseous oxidizer (air), which strikes the head.
• the flame can be kept exposed or it can be confined within open tubular ducts, which have a proximal end that is associated with the manifold body and a distal end that is open for the outflow of the combustion gases. The heat generated by these burners is therefore transmitted to the articles being processed substantially by convection.
• the aim of the present, invention is to eliminate the drawbacks noted above of the background art, by providing an apparatus for thermal treatment of manufactured articles, particularly articles made of ceramic material, which allows optimization of the efficiency of heat exchange with the articles being processed, making it possible to minimize process times, costs linked to fuel consumption, and the space occupation of the apparatus itself, particularly in case of operation in a continuous cycle.
• an object of the present invention is to obtain a uniform distribution of the temperature and of the flow of combustion gases that strike the articles being processed.
• the present apparatus for thermal treatment of articles comprising at least one heated chamber provided with at least one opening for introducing at least one ceramic article to be treated and with at least one opening for extracting said at least one treated article and means for transmitting heat to said at least one article, characterized in that said transmission means comprise at least one radiant tube burner provided with at least one port for the evacuation of the combustion gases which is connected to the inside of said chamber so as to achieve heat propagation by radiation and convection.
• Figure 1 is a schematic transverse sectional view of an apparatus according to the invention, which uses a first type of radiant tube burner;
• Figure 2 is an enlarged-scale schematic view of a detail of Figure 1 relating to the burner;
• Figure 3 is a schematic exploded perspective view of the means for adjusting the placement of the port for evacuating the combustion gases of the burner shown in the preceding figures;
• Figure 4 is a partially sectional schematic plan view of a first embodiment of the apparatus according to the invention, provided with the first type of burner;
• Figure 5 is a schematic and partially sectional plan view of a second embodiment of the apparatus according to the invention, provided with the first type of burner;
• Figure 6 is a schematic transverse sectional view of a further apparatus according to the invention, which uses a second type of radiant tube burner;
• Figure 7 is a schematic perspective view of the radiant tube of the burner of Figure 6;
• Figure 8 is a schematic view, taken from below, of the radiating tube of Figure 7;
• Figure 9 is a partially sectional schematic plan view of a third embodiment of the apparatus according to the invention provided with the second type of burner;
• Figure 10 is a partially sectional schematic plan view of a fourth embodiment of the apparatus according to the invention provided with the second type of burner;
• Figure 1 1 is a schematic and partial transverse sectional view of a further embodiment of the apparatus according to the invention, which uses a third type of radiant tube burner;
• Figure 12 is a schematic partial side elevation view of the burner used in the apparatus of Figure 1 1 ;
• Figure 13 is a schematic partial plan view of the burner of Figure 12;
• Figure 14 is a schematic partial sectional view, taken along the line XIV-XIV of Figure 13;
• Figures 15 is a schematic perspective view of the burner, taken in cross-section as in Figure 14, viewed from below;
• Figure 16 is a schematic side elevation view of the shielding means of the burner of Figures 1 1-15;
• Figure 17 is a schematic front elevation view of the shielding means of Figure 16;
• Figure 18 is a schematic sectional view, taken along the line XVIII- XVIII of Figure 16;
• Figure 19 is a schematic and partially sectional plan view of a fifth embodiment of the apparatus according to the invention, provided with the third type of burner;
• Figure 20 is a schematic partially sectional plan view of a sixth embodiment of the apparatus according to the invention provided with the third type of burner. Ways of carrying out the Invention
• the reference numeral 1 generally designates an apparatus for thermal treatment of manufactured articles M, particularly made of ceramic material, such as tiles, sanitary fixtures, bricks and the like.
• the apparatus 1 comprises at least one heated chamber 2 which has at least one opening 3 for introducing at least, one article M to be treated and at least one opening 4 for extracting the treated article M.
• the apparatus 1 further has means for transmitting heat to the article
• M which consist of at least one burner 5 provided with a radiant tube 6 which is inserted in the chamber 2 and is provided with at least one port 7 for evacuating the combustion gases which is connected to the inside of the chamber so as to achieve a mixed heat propagation both by radiation and by convection.
• the evacuation port 7 is arranged directly inside the chamber 2, but it might also be arranged outside the chamber and be connected to it by means of suitable ducts for the passage of the combustion gases.
• the burner 5 comprises a manifold body 8, which is provided with a port 8a for introducing at least one gaseous fuel, such as methane gas, and a port 8b for introducing at least one gaseous oxidizer, such as air, such ports being associated with respective supply units, which are not shown because they are of a known type.
• a port 8a for introducing at least one gaseous fuel, such as methane gas
• a port 8b for introducing at least one gaseous oxidizer, such as air, such ports being associated with respective supply units, which are not shown because they are of a known type.
• the burner 5 further has a combustion head 9, which is associated with the manifold body 8 so as communicate with it by means of a fuel supply duct 10 and is provided with an ignition electrode 1 1 and with a flame control device 12, of the type of a second electrode.
• the radiant tube 6 comprises a radiant jacket 13, which has a proximal end 13a associated with the manifold body 8 and a distal end 13b, to the lateral wall of which the evacuation port 7 is associated.
• the combustion head 9 is accommodated within the radiant jacket 13.
• the evacuation port 7 consists of a hole that is formed directly in the side wall of the radiant jacket 13.
• the burner 5 can be of the self-recuperative type; the combustion head 9 is in fact arranged along the radiant jacket 13 so as to be spaced from the corresponding proximal end 13a for achieving heat exchange in countercurrent from the combustion gases to the oxidizer that is fed toward said head.
• the burner 5 is provided with means 14 for adjusting the position of the evacuation port 7 in order to direct the flow of combustion gases with respect to the article M ( Figure 3).
• these adjustment means 14 comprise an annular flange 15, which is associated with the proximal end 13a and is provided with a pin 16 which protrudes from the face of the flange that is directed toward the radiant jacket 13 in a position which coincides diametrically with respect to the evacuation port 7.
• the adjustment means 14 further comprise a plate 17 for fixing the radiant jacket 13 to the manifold body 8, provided with a central hole 18 in which said radiant jacket is inserted so as to pass through it and on the peripheral region of which there are a plurality of seats 19 in which the pin 16 can be inserted alternatively.
• the plate 17 is further provided with a plurality of through holes 20 for the insertion of screw means, not shown, for connection to the manifold body 8.
• the plate 17 has nine seats 19, which are distributed on a half-circle at the lower perimeter of the central hole 18 and are arranged symmetrically with respect to a vertical plane that passes through the longitudinal axis of the radiant jacket 13, and each one corresponds to a different angular arrangement of the evacuation port 7 with respect to the longitudinal axis of said radiant jacket, and therefore a different orientation of the outflow direction of the combustion gases from the evacuation port 7 with respect to the article M.
• the outflow direction of the exhaust gases is preferably horizontal or directed downward, the burner 5 being arranged above the article M.
• the burner 5 is arranged so that the manifold body 8 protrudes outside the chamber 2 and so that the radiant tube 6 is supported inside it by at least one first wall 2a that delimits said chamber.
• the apparatus 1 can provide means 21 for supporting the radiant tube 6 which cooperate with the distal end 13b and are associated with a second wall 2b that delimits the chamber 2 and lies opposite the first wall 2a.
• the radiant jacket 13 therefore comprises a shank 22 which protrudes from the distal end 13b and the supporting means 21 have a corresponding seat in which said shank is inserted.
• the radiant jacket 13 has an extension that is substantially of the same order of magnitude as the size of the chamber 2.
• the transmission means preferably comprise a plurality of burners 5 which are arranged with their corresponding radiant tubes 6 in mutually opposite pairs so as to balance the temperature inside the chamber 2.
• the apparatus 1 can operate intermittently ( Figures 4, 9 and 19), with the openings 3 and 4 mutually coinciding, or continuously ( Figures 5, 10 and 20), with the chamber 2 tunnel-shaped, with horizontal or vertical extension, and means 23, of the type of a roller bed or other continuous conveyor of a known type, for transferring a plurality of articles M from the inlet opening 3 to the outlet opening 4.
• the burners 5 are arranged transversely to the direction in which the chamber 2 is crossed.
• the apparatus 1 can provide, for example, a firing or drying treatment of the articles M, both in the unfired state and in the fired state.
• the apparatus 1 uses a first type of burner 5, whose radiant tube 6 comprises an internal jacket 24, which is arranged inside the radiant jacket 13 and is jointly connected thereto so as to form an interspace 25 for the passage of the combustion gases between said jackets, which has a proximal end 24a associated with the manifold body 8 to supply the oxidizer and is provided with at least one opening 26 for the passage of the combustion gases in the interspace 25 proximate to the distal end 24b.
• the combustion head 9 is accommodated inside the internal jacket 24 and is spaced from the corresponding proximal end 24a.
• the evacuation port 7 is associated with the side wall of the radiant jacket 13 at the corresponding proximal end 13a.
• the burner 5 can further have baffle elements 27, which are arranged between the duct 10 and the internal jacket 24 so as to impart a helical motion to the flow of the oxidizer.
• a helical profile 28 is formed on the outer wall of the internal jacket 24 so as to impart a helical motion to the flow of combustion gases along the interspace 25.
• the radiant jacket 13 and the internal jacket 24 have a linear extension, but they might also be shaped differently.
• the internal jacket 24 is arranged concentrically with respect to the radiant jacket 13 and the duct 10 lies along the longitudinal axis of the internal jacket 24.
• each burner 5 can have a plurality of evacuation ports 7 which are distributed on the side wall of the radiant jacket 13 at least at the corresponding proximal end 13a.
• the apparatus 1 uses a second type of burner 5 which has a plurality of evacuation ports 7, which are distributed in a region of the side wall of the radiant jacket 13 that is comprised between the combustion head 9 and the corresponding distal end 13a and is preferably spaced from said combustion head to avoid the escape of tongues of fire through the evacuation ports 7 proximate to the combustion triggering region.
• the evacuation ports 7 have a breadth that increases toward the distal end 13a, so as to avoid the exit of tongues of fire through them, in particular proximately to the combustion head 9. Moreover, the region over which the evacuation ports 7 are distributed has a transverse extension, with respect to the longitudinal extension of the radiant jacket 13, that increases toward the distal end 13a so as to balance the flow-rate of the combustion gases in output from them, taking into account the load losses that occur by moving away from the combustion triggering region. This region therefore has an extension in plan view that is substantially trapezoid or, as an alternative, triangular which diverges toward the distal end 13b.
• such region has a longitudinal extension that is at least equal to half the length of the radiant jacket 13, so as to move beyond the centerline (designated by the reference letter L in the figures) of the chamber 2.
• each pair of consecutive burners 5 provides a distribution of evacuation ports 7 over the entire width of the chamber 2.
• the radiant jacket in an alternative embodiment, which is not shown, the radiant jacket
• the apparatus 1 uses a third type of burner 5, which has a plurality of evacuation ports 7 as described above and is provided with shielding means 30, which cover at least part of the radiant tube 6 externally so as to protect it against any air currents that are present in the space in which said burner is installed and which might cool the radiant tube 6, reducing the effectiveness of the diffusion of heat by radiation.
• the shielding means 30 provide at least one portion
• the substantially reflective portion 31 that substantially reflects the thermal radiation emitted by the radiant tube 6 and at least one portion 32 that is substantially transparent to said radiation.
• the term "transparent” is understood to mean that it can be crossed by thermal radiation.
• the substantially reflective portion 31 is contoured so as to concentrate the thermal radiation at the substantially transparent portion 32. In this manner, it is possible to direct the thermal radiation for installations that require a localized radiation flow rather than a diffuse one.
• the substantially reflective portion 31 comprises a wall made of metal plate, which is contoured so as to form a sort of flared barrel vault, in the inside curve of which the radiant tube 6 is arranged longitudinally.
• the substantially transparent portion 32 is arranged at the base of the vault, which in the illustrated embodiment is open.
• the radiant tube 6 is preferably inserted completely within the inside curve formed by the wall 31.
• the wall 31 covers a length that is substantially equal to the length of the radiant tube 6.
• the shielding means 30 comprise means 33 for supporting the radiant tube 6, which have a plurality of plates 34 which are rigidly connected to the wall 31 and are arranged at right angles to its longitudinal extension, each plate having a seat 35 for accommodating the radiant tube.
• a plate designated by the reference numeral 34a, is provided at the end of the wall 31 that faces the proximal end 13a and is of the type shown in Figure 17, contoured so as to form a perimeter that substantially matches the perimeter formed by the transverse cross-section of the wall 31 , and provided with a closed seat, designated by the reference numeral 35a, in which the radiant tube 6 is inserted so as to pass through snugly.
• a plurality of plates (three in Figure 16), designated by the reference numeral 34b, of the type shown in Figure 18, are distributed along the longitudinal extension of the wall 31 and are contoured so as to occupy only partially the transverse section formed by the wall 31 , and are provided with an open seat, designated by the reference numeral 35b, for supporting the radiant tube 6.
• the shielding means 30 have at least one opening 36 that is formed in the wall 31 at the proximal end 13 a.
• the burner 5 comprises suspension means 37, which are associated with the shielding means 30 for installation of said burner.
• the suspension means 37 have a pair of tension members 38, which are arranged at respective longitudinal ends of the wall 31.
• Each tension member 38 has an end which is associated with the wall 31 and the opposite end which can be associated with a wall of the space in which the burner 5 is installed, for example by means of threaded connecting elements 39, the tension members 38 being threaded externally at their ends.
• the burner 5 is arranged above the manufactured articles M, with the evacuation ports 7 directed toward said articles.
• the shielding means 30 are arranged so that the substantially transparent portion 32 faces the articles M, so as to direct toward them the thermal radiation emitted by the radiant tube 6, reducing dispersion into the surrounding environment.
• the fuel and the oxidizer, fed along the internal jacket 24, generate the flame at the combustion head 9, downstream of which the combustion gases propagate along said internal jacket toward the distal end 24b and from there, through the opening 26, along the interspace 25 toward the proximal end 13a, until they exit through the evacuation port 7.
• the heat of the combustion gases that pass through the interspace 25 is transmitted to the article M by radiation as a consequence of the heating of the radiant jacket 13.
• the introduction of the combustion gases into the chamber 2 through the evacuation port 7 further provides a transfer of heat to the article M by convection.
• the oxidizer is fed directly into the radiant jacket 13 and the portion of radiant tube 6 downstream of the combustion trigger region transfers heat to the article M by radiation, while the portion comprised between the proximal end 13a and the combustion head 9 also provides preheating of the oxidizer, which receives heat both from the combustion gases inside the radiant jacket 13, with which it mixes, and from the chamber 2.
• the combustion gases in output from the evacuation ports 7 transfer heat to the article M by convection.
• evacuation ports 7 make it possible to adjust the amount of heat that is transferred by convection with respect to the amount that is transferred by radiation.

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• 2009
  • 2009-11-19 EP EP09760821.0A patent/EP2373946B1/de not_active Not-in-force
  • 2009-11-19 ES ES09760821.0T patent/ES2519477T3/es active Active
  • 2009-11-19 WO PCT/EP2009/065501 patent/WO2010069706A1/en active Application Filing

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