CN117859033A - Heating assembly and industrial equipment for firing ceramic products - Google Patents
Heating assembly and industrial equipment for firing ceramic products Download PDFInfo
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- CN117859033A CN117859033A CN202280044449.0A CN202280044449A CN117859033A CN 117859033 A CN117859033 A CN 117859033A CN 202280044449 A CN202280044449 A CN 202280044449A CN 117859033 A CN117859033 A CN 117859033A
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- Prior art keywords
- heating assembly
- discharge element
- tubular discharge
- firing chamber
- heating
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- 238000010438 heat treatment Methods 0.000 title claims abstract description 152
- 238000010304 firing Methods 0.000 title claims abstract description 133
- 239000000919 ceramic Substances 0.000 title claims abstract description 67
- 238000005485 electric heating Methods 0.000 claims abstract description 13
- 239000007789 gas Substances 0.000 claims description 76
- 238000000429 assembly Methods 0.000 claims description 15
- 230000000712 assembly Effects 0.000 claims description 15
- 238000001816 cooling Methods 0.000 claims description 6
- 239000012080 ambient air Substances 0.000 claims description 4
- 238000000034 method Methods 0.000 description 7
- 208000031481 Pathologic Constriction Diseases 0.000 description 6
- 208000037804 stenosis Diseases 0.000 description 6
- 230000036262 stenosis Effects 0.000 description 6
- 230000008901 benefit Effects 0.000 description 5
- 238000002485 combustion reaction Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 239000003517 fume Substances 0.000 description 4
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 4
- 230000009467 reduction Effects 0.000 description 4
- 239000004020 conductor Substances 0.000 description 3
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 3
- 229910010271 silicon carbide Inorganic materials 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 239000000470 constituent Substances 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 229910000953 kanthal Inorganic materials 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 230000001737 promoting effect Effects 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 238000010146 3D printing Methods 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 229910010293 ceramic material Inorganic materials 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 238000004512 die casting Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000003546 flue gas Substances 0.000 description 1
- 239000002803 fossil fuel Substances 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 230000000191 radiation effect Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000011819 refractory material Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Classifications
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- 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
- F27D11/00—Arrangement of elements for electric heating in or on furnaces
- F27D11/02—Ohmic resistance heating
-
- 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
- F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
- F27B9/30—Details, accessories, or equipment peculiar to furnaces of these types
- F27B9/36—Arrangements of heating devices
-
- 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
- F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
- F27B9/30—Details, accessories, or equipment peculiar to furnaces of these types
- F27B9/36—Arrangements of heating devices
- F27B2009/3638—Heaters located above and under the track
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Furnace Details (AREA)
- Resistance Heating (AREA)
- Tunnel Furnaces (AREA)
Abstract
An industrial plant (29) for firing ceramic articles (T) and a heating assembly (1), the heating assembly (1) being mountable in a kiln (2) and comprising: an electric heater (5) comprising a tubular housing (6), a feed tube (8) for feeding a gas (G) comprising air, at least one electric heating element operable to heat the gas (G); and a tubular discharge element (10) extending from the tubular casing (6) configured to be flowed therethrough by the gas (G) exiting the electric heater (5) and comprising at least one first guiding outlet (11) for guiding at least a portion of said gas (G) towards said firing chamber (3), the first guiding outlet (11) having a through hole with an equivalent diameter of less than or equal to about 25 mm.
Description
Cross Reference to Related Applications
This patent application claims priority from italian patent application No. 102021000016334 filed on 22 th 6 of 2021 and italian patent application No. 102021000016352 filed on 22 th 6 of 2021, the disclosures of which are incorporated herein by reference in their entireties.
Technical Field
The present invention relates to a heating assembly and apparatus for firing ceramic articles. In particular, the invention has advantageous, but not exclusive, application to the firing of ceramic articles for obtaining tiles, to which the following description will make explicit reference, without thereby losing generality.
Background
Firing of the ceramic articles for obtaining tiles is generally carried out in a tunnel kiln delimited by two opposite walls and a roof.
Such kilns are typically heated by two sets of burners, typically driven by methane gas, each set on one side of the tunnel. These burners are typically located at multiple heights on the side walls of the tunnel and face the opposing wall portions, and the ceramic articles are typically conveyed on a large conveyor comprising a series of ceramic rollers.
The firing cycle of ceramic articles is designed to have a high degree of precision and involves: heating ceramic articles from the kiln inlet, maintaining them in the firing chamber at a predetermined temperature, and cooling them in a controlled manner before reaching the kiln outlet. It is therefore important to ensure that the temperature within the firing chamber is uniform across the width of the kiln. For this purpose, different types of industrial burners and different burner arrangements within industrial equipment have been developed to achieve increasingly constant temperatures within the combustion chamber.
However, ceramic burners of known type are essentially fuelled with fossil fuels (methane, LPG), which, although on the one hand, allow the reduction of NO by conventional combustion X Emissions, but on the other hand, lead to the development of a reverse-ecology of non-renewable energy sources and CO 2 And all other combustion waste emissions.
To overcome these problems, methods of electrically heating kilns for firing ceramic articles have been proposed, for example involving the installation of heating rods or heating conductors in the kiln compartments to radiate heat and heat the kiln itself.
However, these known firing methods also have some drawbacks. One of the main drawbacks is related to the aggressiveness of the fumes generated by the firing of the ceramic articles, in particular in the preheating zone of the kiln itself, which can rapidly corrode the heating rods or conductors installed in the kiln, with the result that frequent maintenance or replacement of these heating elements must be carried out. In an attempt to overcome this problem, these heating rods or conductors are usually installed only in the firing zone of the kiln, where the generated fumes are not particularly chemically aggressive, while industrial burners of known type are used in the preheating zone.
Furthermore, regardless of whether electricity from the power grid or from the interior is used, it is more expensive to electrically heat the kiln used to fire the ceramic article than to use fuel or gas.
Another disadvantage of the known methods of electrically heating kilns for firing ceramic articles is that the radiation effect is often too great, which does not allow for a uniform heat distribution in large combustion chambers.
Yet another disadvantage of the known method of electrically heating a kiln for firing ceramic articles relates to the inability to uniformly fire the body of the ceramic article throughout its cross-section. In particular, ceramic articles up to 6mm thick can only be fired uniformly over the entire thickness using known methods.
The object of the invention is to achieve that at least part ofOvercomes the disadvantages of the prior art separately and at the same time is easy and inexpensive to implement and at least reduces CO 2 Discharged heating assemblies and industrial equipment for firing ceramic articles.
Disclosure of Invention
According to the present invention, a heating assembly and an industrial apparatus for firing ceramic articles are proposed as claimed in the appended independent claims, preferably in any one of the claims depending directly or indirectly on said independent claims.
The claims describing the preferred embodiments of the invention form an integral part of the present description.
Drawings
The invention will now be described with reference to the accompanying drawings, which illustrate some non-limiting embodiments, in which:
FIG. 1 shows a schematic front cross-sectional view of an industrial apparatus for firing ceramic articles according to an embodiment of the invention;
FIGS. 2, 2A, 4, 6, 8 and 10 are perspective views of heating assemblies according to various embodiments of the present invention;
FIG. 3 is a front cross-sectional view of the heating assembly of FIG. 2 installed in a kiln for firing ceramic articles;
FIG. 3A is a front cross-sectional view of the heating assembly of FIG. 2A installed in a kiln for firing ceramic articles;
FIG. 5 is a front cross-sectional view of the heating assembly of FIG. 4 installed in a kiln for firing ceramic articles;
FIG. 5A illustrates two side views of a portion of the heating assembly of FIG. 4 from two different perspectives;
FIG. 7 is a front cross-sectional view of the heating assembly of FIG. 6 installed in a kiln for firing ceramic articles;
FIG. 7A illustrates two side views of a portion of the heating assembly of FIG. 6 from two different perspectives;
FIG. 9 is a front cross-sectional view of the heating assembly of FIG. 8 installed in a kiln for firing ceramic articles;
FIG. 9A illustrates two side views of a portion of the heating assembly of FIG. 8 from two different perspectives;
FIG. 11 is a front cross-sectional view of the heating assembly of FIG. 10 installed in a kiln for firing ceramic articles;
FIG. 11A is an enlarged view of a portion of the heating assembly of FIG. 11;
FIG. 12 is a perspective view of a drain element forming part of a heating assembly according to another embodiment of the invention;
FIG. 13 is a side cross-sectional view of the discharge element of FIG. 12;
FIG. 14 is a graph showing temperature variation in the firing chamber of the kiln as a function of distance from the point where hot gas enters the kiln (the abscissa indicates distance and the ordinate indicates temperature); and is also provided with
Fig. 15 is a graph showing a change in outflow velocity of hot gas in a firing chamber of a kiln according to a distance from a point at which the hot gas is introduced into the firing chamber (an abscissa indicates distance, and an ordinate indicates temperature).
Detailed Description
In the drawings, reference numeral 1 generally designates a heating assembly for firing ceramic articles T according to a first aspect of the present invention.
In detail, in the present description, ceramic article T is understood to mean any type of article made of ceramic material, such as ceramic sheets or tiles, that requires at least one firing cycle in industrial kiln 2 (for example partially shown in fig. 1).
The heating assembly 1 may be installed in an industrial kiln 2, in particular a tunnel kiln 2, comprising a firing chamber 3.
In particular, as schematically illustrated in fig. 1, advantageously but without limitation, while firing, the ceramic article T is moved along a conveying path P (schematically illustrated in fig. 1 and extending orthogonally to the plane of view in fig. 1) by a conveying system 4.
According to some advantageous but non-limiting embodiments, the conveyor system 4 comprises a series of rollers arranged consecutively in a direction parallel to the conveying path P, on which the unfired ceramic articles T to be fired are preferably arranged in a regular manner.
In detail, advantageously, but not by way of limitation, the conveyor system 4 comprises a plurality of ceramic rollers (possibly also moving at different speeds to distinguish the firing of the articles) arranged in succession along the conveyor path P (i.e. in a direction parallel to the conveyor path P) so as to define a conveyor plane for receiving the ceramic articles T and moving them along the conveyor path P.
With particular reference to fig. 2-11, advantageously but without limitation, the heating assembly 1 comprises an electric heater 5 comprising a tubular housing 6 having at one end 7 a feed tube 8 for feeding a gas G (schematically represented by arrows in fig. 3, 3A, 5, 7, 9 and 11) inside the tubular housing 6, and at least one electric heating element (not shown in the figures) extending inside the tubular housing 6 and operable to heat the gas G by the joule effect.
In detail, the gas G advantageously comprises (in particular consists of) ambient air, for example having at least 21% oxygen.
Advantageously, but not by way of limitation, the electric heater 5 further comprises at least one bracket (not visible in the drawings) attached inside the tubular housing 6 and configured to support at least the electric heating element to keep it fixed with respect to the tubular housing 6.
This arrangement of the electric heating element within the housing 6 protects the electric heating element from any chemical attack by the fumes and/or exhaust gases from the firing chamber 3, increasing the service life of the heating assembly 1 compared to known electric heating assemblies for firing ceramic articles T.
According to some advantageous but non-limiting embodiments, the support comprises (in particular consists of) a plurality of bars, more advantageously a plurality of bars arranged to define a plurality of hollow channels between them. Advantageously, but not exclusively (in this example), the electric heating element comprises (in particular consists of) a heating wire, for example a Kanthal heating wire, wound around each/the rod and configured to heat the gas G flowing through the tubular housing 6 by the joule effect.
According to an alternative embodiment, the support element comprises a plurality of perforated baffles (not visible in the figures) extending in a radial direction with respect to the tubular casing 6 and arranged one after the other along the longitudinal axis X of the tubular casing 6 itself, so as to define a plurality of longitudinal channels open at least at the ends.
Furthermore, advantageously, but not limitatively, the electric heating element comprises (in particular consists of) a heating wire, such as a Kanthal heating wire, which extends through the holes, for example helically wound into a plurality of adjacent holes, and is configured to heat the gas G flowing through the tubular housing 6 by joule effect.
According to some advantageous but non-limiting embodiments, the electric heater 5 further comprises a thermal insulation layer (not visible in the figures) provided at the end 9 of the tubular casing 6 opposite to the end 7 and provided with an opening (not visible in the figures) configured to allow the gas G to flow out of the tubular casing 6. Advantageously, but not by way of limitation, the opening is configured to fluidly connect the electric heater 5 with the tubular discharge element 10, as will be better described below.
Advantageously, but not limitatively (according to some not shown embodiments), the heating assembly 1, in particular the electric heater 5, also comprises at least one temperature control device (not shown) and advantageously at least one thermocouple for detecting the temperature (of the gas G) inside the electric heater 5. Alternatively or in combination, the heating assembly 1, in particular the electric heater 5, also comprises at least one control unit (not shown), which controls the operation of the electric heater 5, possibly in a known manner, according to the data recorded by the temperature control device.
According to some advantageous but non-limiting embodiments, the electric heater 5 is a commercially known product described in one of the patent documents WO2020193479, EP3721150 and EP 3721149.
Advantageously, but not by way of limitation, the heating assembly 1 further comprises a tubular discharge element 10 extending from the tubular housing 6 of the electric heater 5 (in particular from the end 9 of the electric heater 5) on opposite sides of the feed pipe 8, configured to receive the gas G flowing out of the electric heater 5 and to be flown therethrough and comprising at least one guiding outlet 11 for guiding at least a portion of said gas G towards the outside of the tubular discharge element 10 (in particular towards the outside of the heating assembly 1, more in particular towards said firing chamber 3 of the kiln 2 in use).
Advantageously, the pilot outlet 11 has a through hole with an equivalent diameter of less than or equal to about 25 mm. More advantageously, but not by way of limitation, the through hole of the pilot outlet 11 has an equivalent diameter of less than or equal to about 20mm, in particular less than or equal to about 15 mm. Alternatively or in combination, more advantageously but without limitation, the through hole of the at least one pilot outlet 11 is greater than or equal to about 15mm, in particular about 10mm.
It should be noted that in this context, the expression "equivalent diameter" of a through hole must be understood as the diameter of a circle having the same area as the through hole.
In use, this size of the outlet 11 allows to increase the speed at which said gas G is introduced into the firing chamber 3 from the tubular discharge element 10 after being heated. This makes the gas flow G more linear within the firing chamber 3, allowing a more uniform temperature within the firing chamber 3 itself. In addition, this dimension increases the turbulent motion within the tubular discharge element 10, thus promoting the exchange of heat between the electric heating element and the gas G.
Advantageously, but not necessarily (as shown in the non-limiting embodiment of fig. 2-11), the tubular discharge element 10 comprises an end 12 coupled with a portion 13 of the tubular casing 6 and an end 14 opposite to the end 12.
Advantageously, but not by way of limitation (as shown in the non-limiting embodiment of fig. 2-11), the outlet 11 is provided at the end 14.
More precisely, as will be explained more fully below, according to some non-limiting embodiments (for example as shown in figures 2, 2A, 3A, 6, 7A, 8, 9A, 10 and 11), the pilot outlet 11 is arranged along the longitudinal symmetry axis X of the tubular discharge element 10; more advantageously, the through holes of the pilot outlets 11 are arranged along the longitudinal symmetry axis X; more advantageously, this through hole of the pilot outlet 11 is centred with respect to the axis X, i.e. the longitudinal symmetry axis of the tubular discharge element 11. Alternatively (according to a further non-limiting embodiment, such as that shown in fig. 4, 5A, 12 and 13), the pilot outlet 11 is provided on a wall 16 of the end 14.
Advantageously, but not by way of limitation (in the embodiment shown), the discharge element 10 is substantially coaxial with the tubular casing 6. In more detail, the tubular discharge element 10 comprises a longitudinal symmetry axis X which advantageously, but not exclusively, coincides with (i.e. is co-linear with) the longitudinal symmetry axis X of the tubular casing 6.
According to some advantageous but non-limiting embodiments, the tubular discharge element 10 comprises at least one further guiding outlet 11' for guiding at least one (respective) further portion of the gas G towards the outside of the tubular discharge element 10, in particular towards the outside of the heating assembly 1, more in particular towards the firing chamber 3 of the kiln 2 in use.
More advantageously (as in the non-limiting embodiments shown in fig. 4, 5a;6, 7A, 8, 9A, 12 and 13), the tubular discharge element 10 comprises a plurality of further guiding outlets 11' for guiding at least one (respective) further portion of the gas G towards the outside of the tubular discharge element 10, in particular towards the outside of the heating assembly 1, more in particular towards the firing chamber 3 of the kiln 2 in use.
Advantageously, the or each further pilot outlet 11 'or 11' (also) has a respective through hole with an equivalent diameter of less than or equal to about 25mm, in particular less than or equal to about 20 mm. Advantageously, but not limited to, a further pilot outlet 11 '(or each further pilot outlet 11') is also provided at the end 14.
According to some non-limiting embodiments (when provided) such as shown in fig. 2, 3, 6, 7A, 8, 9 and 9A, the or each further pilot outlet 11' is provided on a wall 16 of the end 14. More advantageously, but not by way of limitation, the through hole of the or each further pilot outlet 11' has an equivalent diameter of less than or equal to about 20mm, in particular less than or equal to about 15 mm. More advantageously, the through hole of the or each further pilot outlet 11' is greater than or equal to about 15mm, in particular about 10mm.
Advantageously, but not necessarily (as in the embodiment shown in fig. 4, 5A, 6, 7A), a portion of the pilot outlet 11' comprises one portion of the corresponding hole having a first equivalent diameter (value) and at least one further portion of the corresponding hole having a second equivalent diameter (value) different from the first equivalent diameter (value). Alternatively (according to other advantageous but non-limiting embodiments, such as shown in fig. 8, 9A, 12 and 13), the respective holes of each second pilot outlet 11 'are identical (i.e. have the same equivalent diameter) to the other pilot outlets 11'.
Advantageously, but not by way of limitation, the end 12 of the tubular discharge element 11 is configured to be coupled to the portion 13 of the tubular casing 6; in particular, according to some non-limiting embodiments (such as that shown in fig. 2-11), the end 12 is configured to externally encase a portion 13 of the tubular housing 6 to fluidly connect the tubular housing 6 of the electric heater 5 with the tubular discharge element 10 such that the aforementioned gas G may flow within the tubular discharge element 10; in other words, the tubular casing 6 fits in the tubular discharge element 10 at said end 12.
Advantageously, but not necessarily, the tubular discharge element 10 has a circular cross section, in particular a constant diameter. In addition, the tubular discharge element 10 is advantageously, but not necessarily, made in one piece, in particular of silicon carbide.
Advantageously, but not necessarily, the tubular casing 6 (also) has a circular cross section, in particular a constant diameter.
According to some advantageous but non-limiting embodiments (such as that shown in fig. 2-9A, 12 and 13), the tubular discharge element 10 comprises a hollow body portion 17, which advantageously but not necessarily extends without interruption from the end portion 12 to the end portion 14, and is configured to receive and to flow through the gas G exiting the electric heater 5.
According to some advantageous but non-limiting embodiments (for example as shown in fig. 2, 3, 6, 7A, 8, 9 and 9A), the end portion 14 comprises, in particular defines, a tapering portion 18 configured to guide the gas G coming from the hollow body portion 17 towards the guiding outlet 11.
The presence of the taper 18 further increases the velocity of the gas G flowing out of the tubular discharge element 10, in particular from the outlets 11 and/or 11', further increases the turbulent motion within the tubular discharge element 10 and thus promotes heat exchange between the electric heating element and the gas G. Furthermore, the taper 18 causes a pressure drop and thus a flow rate reduction of the gas G, with the advantage of increasing the temperature of the gas G by the joule effect to the same amount as the heat generated by the electric heater 5.
In detail, with particular reference to the non-limiting embodiment of fig. 6, 7 and 7A, the tubular discharge element 10 has (at least at the hollow body portion 17) a substantially circular cross section and has, in addition to the outlet 11 arranged along the longitudinal symmetry axis X of the tubular discharge element 10, a plurality of pilot outlets 11', for example 3 pilot outlets 11' in the example shown, arranged on the end portion 14, in particular on the wall portion 16 of the tapering portion 18, aligned with each other and each having a through hole with an equivalent diameter value different from each other; in particular, these guiding outlets 11' have through holes with equivalent diameter values increasing towards the outside along the extension of the taper 18, i.e. through the hollow body 17.
According to an alternative non-limiting embodiment, such as shown in fig. 8, 9 and 9A, the tubular discharge element 10 has a substantially circular cross section and has, in addition to the outlets 11 arranged along the longitudinal symmetry axis X of the tubular discharge element 10, a plurality of outlets 11' all having the same equivalent diameter (value) arranged on the wall 16 of the end portion 14.
According to other non-limiting embodiments such as those shown in fig. 4, 5A, the tubular discharge element 10 has a substantially circular cross section and has a series of outlets 11, 11' all provided on the wall 16 of the end 14. Advantageously, a portion of these outlets 11, 11 'has a first equivalent diameter (value) and a second portion of these outlets 11, 11' has a second equivalent diameter (value) different from the first equivalent diameter (value); in particular, the outlets 11, 11 'having the first equivalent diameter (value) and the outlets 11, 11' having the second equivalent diameter (value) are alternately arranged with each other.
According to a further advantageous but non-limiting embodiment, such as that shown in fig. 12 and 13, the tubular discharge element 10 has a substantially circular cross section and has a plurality of outlets 11 or 11 'arranged on the side wall 16 of the end portion 14 aligned with each other along a direction parallel to the longitudinal symmetry axis X of the tubular discharge element 10, such that, in use, at least a portion of the gas G flowing out of each of said outlets 11 or 11' forms a series of parallel flows of gas G towards the outside, in particular towards the firing chamber 3.
According to some advantageous but non-limiting embodiments (for example as shown in fig. 10, 11 and 11A), the heating assembly 1 further comprises: a hollow body 20 coupled to the tubular discharge element 10 to be flowed therethrough (at least by at least a portion of the gas G flowing out of the tubular discharge element 10 through the inlet outlet 11); a suction element 21 advantageously arranged between the tubular discharge element 10 and the hollow body 20; and a guiding outlet 11 "for guiding said at least one portion of said gas G towards the outside of the hollow body 20, in particular towards the outside of the heating assembly 1, more in particular towards said firing chamber 3 of said kiln 2 in use.
Advantageously, but not by way of limitation, the pilot outlet 11 is provided on the hollow body 20, more particularly along the longitudinal symmetry axis X of the tubular outlet element 10, and coaxial with the pilot outlet 11 described above.
Furthermore, advantageously, but not by way of limitation, said pilot outlet 11 "has a through hole with an equivalent diameter less than or equal to about 60 mm.
According to some non-limiting embodiments, such as those shown in fig. 10, 11 and 11A, the hollow body 20 comprises an end 19, and said pilot outlet 11″ is advantageously, but not limitatively, provided on the hollow body 20 (in particular at the end 19 of the hollow body 20, more in particular facing inwards towards the firing chamber 3, in use, i.e. when the heating assembly 1 is assembled in the kiln 2).
Advantageously, in this example, the tubular discharge element 10 is located between the electric heater 5 and the suction element 21.
Advantageously, but not necessarily, as shown in the non-limiting embodiment of fig. 11, in use, the hollow body 20 is (entirely) located inside the firing chamber 3.
The suction element 21 is (advantageously but not limited to) configured to, in use (i.e. when installed in the kiln 2), introduce at least a portion of the exhaust gases F located outside the heating assembly 1 (in particular outside the tubular discharge element 10) into the hollow body 20 and has one or more openings 22 provided between the tubular discharge element 10 and the hollow body 20. The introduction of the exhaust gases F, which have been heated in combination with the above-mentioned gases G in the tubular discharge element 10, promotes the return of the gases F towards the kiln wall and the heating of the gases G, and maintains their velocity and pulse towards the centre of the chamber of the kiln 2. In general, the gas turbulence of the flue gas in the firing chamber 3 is increased, thereby improving the uniformity of the temperature across the width of the firing chamber 3 of the kiln 2 and the heat exchange with the material.
Advantageously, but not by way of limitation, the suction element 21 is configured to generate a vacuum between the tubular discharge element 10 and the hollow body 20, so as to introduce, in use, at least a portion of the exhaust gases F present in the firing chamber 3 into the hollow body 20. The introduction of the exhaust gas F, which has been heated in combination with the above-mentioned gas G inside the tubular discharge element 10, promotes the heating of the gas G and increases its turbulence.
Advantageously, but not by way of limitation, the openings 22 extend through the suction element 21 (e.g. they have an elongated shape and are longitudinally arranged with respect to the tubular discharge element 10 and the hollow body 20).
According to some non-limiting embodiments (such as that shown in fig. 10 and 11), the tubular discharge element 10 is substantially coaxial with the hollow body 20. In other words, the longitudinal symmetry axis X of the tubular discharge element 10 coincides with the longitudinal symmetry axis X of the tubular discharge element 10 and the hollow body 20.
According to some non-limiting embodiments, the suction element 21 comprises, in particular acts as, a venturi.
Furthermore, according to some non-limiting embodiments (e.g. as shown in fig. 11A), the suction element 21 has a constriction 23. In addition, the suction element 21 has a frustoconical portion 24 delimited by a large base 25 and a small base 26. More specifically, advantageously, but not necessarily, the small base 26 coincides with the narrow portion 23 described above; the large base 25 is coupled with the second hollow body 20. Advantageously, but not necessarily, the opening 22 is formed on a frustoconical portion 24 of the suction element 21. In particular, they span from one side (transversely) to the other side of the joint conical portion 24 of the suction element 21.
Advantageously, but not necessarily (and as shown in fig. 10, 11 and 11A), the suction element 21 (also) comprises stiffening ribs 27. Thanks to these stiffening ribs 27, it is possible to lengthen the hollow body 20 as desired without the risk of breaking the tubular discharge element 10 at the portion with the smallest cross section, i.e. at the suction element 21, as a result.
Advantageously, but not necessarily, the tubular discharge element 10 has a circular cross section, in particular a constant diameter.
Advantageously, but not necessarily, the hollow body 20 has a circular cross section, in particular a constant diameter.
Advantageously, but not necessarily, the suction element 21 has a circular cross section.
Advantageously, but not necessarily, the suction element 21 comprises a circular cross-section with a substantially variable diameter.
Advantageously, but not necessarily, the diameter of the narrow portion 23, i.e. of the cross section of the restriction 23 (fig. 11A), is less than two thirds of the diameter of the tubular discharge element 10 and of the hollow body 20. More specifically, the diameter of the cross section TT (fig. 11A) of the narrowed portion 23 is smaller than half the diameter of the tubular discharge element 10 and the hollow body 20.
More specifically, advantageously, but not necessarily, the diameter of the stenosis 23, i.e. the cross section TT (fig. 11A) of the stenosis 23, is less than one third of the diameter of the tubular discharge element 10 and the hollow body 20. In particular, the diameter of the cross section TT of the narrow portion 23 is greater than one sixth of the diameter of the tubular discharge outlet 10 and the hollow body 20.
More advantageously, but not necessarily, the diameter of the stenosis 23, i.e. the cross section TT (fig. 4) of the stenosis 23, is less than one third of the diameter of the tubular discharge element 10 and the second hollow body 20.
In particular, in this example, advantageously but without limitation, the diameter of the stenosis 23 (i.e., the cross-section TT (fig. 11A) of the stenosis 23) is in the range of about 10mm (particularly about 20mm, more particularly about 25 mm) to about 60mm (particularly about 40mm, more particularly about 35 mm). Advantageously, but not by way of limitation, the diameter of the tubular discharge element 10 and the hollow body 20 is between about 30mm (in particular about 40mm, more in particular about 50 mm) and about 200mm (in particular about 120mm, more in particular about 100 mm).
The more the diameter of the constriction 23 is reduced with respect to the diameter of the tubular discharge element 10, the greater the variation in the speed at which the gas G moves inside the hollow body 19. The increase in velocity is advantageous because it allows the gas G to flow out at a greater velocity and increases the turbulence of the gas G within the heating assembly 1, advantageously increasing the heat exchange between the gas and the electric heating element.
In the non-limiting embodiment of fig. 10, 11 and 11A, the tubular discharge element 10, the hollow body 20 and the suction element 21 form a single body, more advantageously formed as a single piece, in particular made of silicon carbide.
In particular, the side surfaces 28 of the tubular discharge element 10, the hollow body 20 and the suction element 21 are (at least partially) free of discontinuities. More specifically, the side surface 28 is uninterrupted in the portion not interrupted by the opening 22 (see fig. 10 and 11).
Advantageously, but not necessarily, the unitary body (comprising the tubular discharge element 10, the hollow body 20 and the suction element 21) is formed in one piece, in particular made of silicon carbide.
Alternatively, advantageously but not necessarily, the unitary body (comprising the tubular discharge element 10, the hollow body 20 and the suction element 21) is made by additive manufacturing, in particular 3D printing. Alternatively, the unitary body is formed by welding together a plurality of constituent elements (in this example, the tubular discharge element 10, the hollow body 20 and the suction element 21).
According to a further non-limiting and not shown embodiment, the unitary body (comprising the tubular discharge element 10, the hollow body 20 and the suction element 21) is formed by mechanically coupling a plurality of constituent elements (in this example, the tubular discharge element 10, the hollow body 20 and the suction element 21) by means of a fastening system (e.g. bolts, screws, rivets, etc.).
According to a further non-limiting embodiment, the unitary body (comprising tubular discharge element 10, hollow body 20 and suction element 21) is formed by die casting techniques.
According to some not shown embodiments, the heating assembly 1 comprises a plurality of hollow bodies (similar to the hollow body 20) sandwiching respective suction elements (of the type of the suction element 21).
According to some not shown embodiments, the heating assembly 1 comprises a high-pressure fan for sending the gas G (in particular ambient air comprising oxygen having at least 21%) to the electric heater 5. This advantageously allows compensating at least a part of the pressure loss of the gas G as it flows through the tubular housing 6 and the discharge element 10 and thus compensating the flow rate loss, thus maintaining its flow rate.
Referring particularly to FIG. 1, in accordance with another aspect of the present invention, an industrial apparatus for firing ceramic articles T is provided, indicated by reference numeral 29.
The industrial plant 29 comprises a kiln 2 (as described above), in particular a tunnel kiln, having at least one side wall 30 and a roof or dome 31 delimiting a firing chamber 3, having a surface 32 inside the firing chamber 3 and a surface 33 outside the firing chamber 3.
In particular, kiln 2 advantageously has the form of a tunnel with two opposite wall portions 30' and 30″ forming side walls 30 and a roof or dome 31 between which ceramic articles T are conveyed.
The industrial plant 29 further comprises a conveyor system 4 (as described above), in particular horizontal, which (as described above) is adapted to move a plurality of ceramic articles T along a conveying path P (from an inlet to an outlet of the firing chamber 3) within the firing chamber 3.
The conveyor system 4 may be any type of conveyor system.
Advantageously (as described above), the conveyor system 4 comprises a series of rollers made of refractory material, on which the raw ceramic products T to be fired are placed, preferably in a regular manner. More specifically (according to some advantageous but non-limiting embodiments), the conveyor system 4 comprises a plurality of ceramic rollers defining a conveying plane (possibly moving at different speeds to distinguish between the firing of the articles).
The apparatus 29 further comprises a heating system 34 (in particular as shown in fig. 1) configured to heat the firing chamber 3 to fire a plurality of ceramic articles T passing inside said firing chamber 3 and obtain a final ceramic article, such as a tile.
Advantageously, the heating system 34 comprises at least one heating assembly 1. More advantageously, the heating system 34 comprises a plurality of heating assemblies 1 arranged in series along a direction parallel to the conveying path P.
In more detail, and with particular reference to fig. 1, the heating assemblies 1, and in particular each heating assembly 1, are advantageously formed as described above.
Advantageously, but not by way of limitation, the firing chamber 3 of the kiln 2 comprises (in particular split into) at least one preheating zone, one pre-firing zone, one firing zone and one cooling zone (one after the other) arranged along the conveying path P. Advantageously, but not necessarily, the preheating zone is connected to the pre-firing zone and to the firing zone (without discontinuities), more particularly in a direct manner (i.e. without the interposition of further zones and/or chambers). Advantageously, the firing zone and the cooling zone are also advantageously, but not necessarily, connected (without discontinuities), in particular in a direct way (i.e. without the interposition of further chambers and/or zones).
In detail, in the preheating zone and in the pre-firing zone, the temperature of the ceramic article T is gradually increased until a firing temperature of at least about 1100 ℃, in particular at least about 1200 ℃, is reached, which remains constant throughout the firing zone; however, in the cooling zone, the temperature of the fired base ceramic article BC exiting the firing zone 6 decreases rapidly.
Advantageously, but not by way of limitation, at least a portion of the heating assembly 1 is arranged at the preheating zone (in particular also in the pre-firing zone) to heat at least the preheating zone of the firing chamber 3, so as to generate a temperature in the preheating zone of at least about 1000 ℃, in particular of at least about 1100 ℃.
Advantageously, but not limitatively, according to some non-limiting and not illustrated embodiments, the heating system 34 of the apparatus 29 further comprises a plurality of heating elements arranged inside the firing chamber 3The electric radiation plates are in particular arranged on the surface 32 of the dome or roof 31 of the firing chamber 3 of the kiln and above the surface of the bottom or base or floor 35. The function of these radiation plates is to generate the above-mentioned firing temperatures within the firing zone itself. Thus, an all-electrically controlled firing apparatus 29 for firing ceramic articles T can be formed, which has the advantage of a significant reduction in CO 2 And (5) discharging.
According to some advantageous but non-limiting embodiments, the heating assemblies 1 are arranged in the side walls 30 of the kiln 2 (in particular the above-mentioned side walls 30', 30″ of the kiln 2), i.e. they are mounted on the walls in the kiln, at a plurality of heights.
In detail, advantageously, in the case of a conveyor system 4 comprising the ceramic rollers described above (constituted by them), at least a portion of the heating assembly 1 is arranged below the conveying plane. The presence of the heating assembly 1 also below the transport plane enables a more even distribution of heat inside the firing chamber 3.
In combination (as shown in the non-limiting embodiment shown in fig. 1) or alternatively, at least a portion of the heating assembly 1 is provided at the top or dome 31 of the kiln 2. In detail, advantageously but without limitation, the/each heating assembly 1 provided on the roof or dome 31 is mounted obliquely with respect to the vertical direction and/or with respect to the conveying path P of the ceramic articles, in particular at an angle varying between about 0 ° and about 60 ° with respect to the vertical direction and/or at an angle varying between 0 ° and 60 ° with respect to the conveying path P.
Advantageously, the heating assembly 1 is arranged (i.e. mounted) on the kiln 2 so as to be oriented in a direction transversal (i.e. perpendicular) to the advancing direction a (and thus to the conveying path P).
The counter-flow arrangement of the heating assembly 1 (i.e. orthogonal to the advancing direction of the ceramic articles T) allows avoiding the risk of the gas jets G exiting the heating assembly 1 reaching directly at the ceramic articles T and therefore damaging them.
Advantageously, but not necessarily, the/each heating assembly 1 is arranged (i.e. mounted) such that at least a portion of the tubular discharge element 10 protrudes at least partially into the firing chamber 3.
In more detail, according to some advantageous but non-limiting embodiments, the tubular discharge element 10 of the (each) heating assembly 1 has a length of at least about 900mm, and the heating assembly 1 is mounted such that said discharge element 10 protrudes within the firing chamber 3 by a length of at least about 600 mm.
According to a further advantageous but non-limiting embodiment, as shown in fig. 12 and 13, the tubular discharge element 10 is configured (in particular, sized) so as to cross the firing chamber 3 in a lateral direction, so as to orient the above-mentioned pilot outlets 11, 11' towards the central portion of the firing chamber 3. More particularly, in this example, the heating assembly 1 is mounted such that the tubular discharge element 10 can protrude (i.e. flow out) from a first side of the side wall 30 (in particular from the wall portion 30'), extend through said firing chamber 3 to a second side opposite to the first side (in particular to the wall portion 30 "). Advantageously, in this example, the tubular discharge element 10, in particular the end 14 thereof, spans the entire firing chamber 3 and fits in the side wall 30 ".
Advantageously, but not by way of limitation, the/each heating assembly 1 is arranged (i.e. mounted) such that the electric heater of the (in particular each) heating assembly 1 extends at least partially (in particular fully) through (in particular transversely) a side wall or roof or dome 31 of the kiln 2 or between an inner surface and an outer surface of the firing chamber 3.
According to some advantageous but non-limiting embodiments (for example, as shown in fig. 10-13), when the heating assembly 1 comprises (in particular also at least is formed of) the hollow body 20 and the suction element 21 described above, the heating assembly 1 is mounted such that the suction element 21 is at least partially disposed inside the firing chamber 3.
Alternatively or in combination, advantageously but not limitatively, in this example (when the heating assembly 1 further comprises the hollow body 20 and the suction element 21 described above), the heating assembly 1 is mounted such that the electric heater 5 extends at least partially (in particular completely) through (in particular transversely) the side wall 30 or the roof or dome 31 of the kiln 2 between the inner surface 32 and the outer surface 33; the tubular discharge element 10 extends at least partially (in particular completely) through (in particular transversely) a side wall 30 or roof or dome 31 of the kiln 2 between an inner surface 32 and an outer surface 33; and the hollow body 20 extends substantially entirely within the firing chamber 3.
According to some non-limiting and not illustrated embodiments, advantageously but not necessarily, the heating assembly 1 is mounted so that the tubular discharge element 10 protrudes at least partially into the firing chamber 3.
In the graph of fig. 14, the temperature trend is shown as a function of the distance from the outlet 11 of the heating assembly 1; the graph was obtained experimentally. In particular, the axis of the ordinate represents the temperature inside the firing chamber 3 and the axis of the abscissa represents the distance between the guiding outlet 11 of the heating assembly 1 coinciding with the side wall of the kiln 2. In detail, the temperature variation indicated with line I represents the device 29 with a high-speed gas burner of known type, whereas the temperature variation indicated with lines II and III represents the device 29 comprising a heating assembly 1 with an electric heater 5 of the type described above but with an outlet 11 comprising a through hole with an equivalent diameter (increasing from line I to line III but) greater than about 25mm, whereas the temperature variation indicated with lines IV and V represents the device 29 and the heating assembly 1 formed according to two different embodiments of the invention (in particular, line V represents the heating assembly 1 comprising a tubular discharge element 10 comprising an outlet 11 comprising a through hole with an equivalent diameter of about 25mm and line IV represents the heating assembly 1 also comprising a hollow body 20 and a suction element 21). It is therefore evident that by using the device 29 and the heating assembly 1 according to the invention, a more uniform and constant temperature value is obtained than in the known devices having gas burners within a certain distance from the wall 32 of the kiln 2. In practice, conventional gas burners may have more or less enhanced "hot spots" depending on the configuration of their burner heads. Reducing the equivalent diameter of the through holes of the outlet 11 results in an increase in the back pressure of the gas G flowing out of the outlet portion 11, thus increasing the temperature and speed of the gas G flowing out of the heating assembly 1 and thus more uniformly heating the firing chamber 3.
In fig. 15, lines I and II represent devices with gas burners of known type, lines III and IV represent devices 29 comprising a heating assembly 1 with an electric heater 5 of the type described above but with a tubular discharge element 10 having an outlet 11 with a through hole of equivalent diameter (increasing from line III to line IV but) greater than about 25mm, while lines V and VI represent devices 29 and heating assemblies 1 formed according to one of the two embodiments of the invention (in particular, line VI represents a heating assembly 1 with a tubular discharge element 10 having an outlet 11 with a through hole of equivalent diameter about 25mm, and line V represents a heating assembly 1 also having a hollow main figure 20 and a suction element 21). This view shows the trend of the flame speed (lines I and II) or hot gas G (lines III, IV, V and VI) inside the firing chamber 3 as a function of the distance from the outlet 11 of the heating assembly 1 coinciding with the side wall of the kiln 2.
The graph was also obtained experimentally. From this graph it is also derived that the narrowing of the equivalent diameter of the through hole of the pilot outlet 11 increases the back pressure of the gas G flowing out of the pilot outlet 11, increasing its temperature and the outflow speed of the gas G, which becomes more similar to the results produced by the structures known in the literature with high-speed gas burners (curves I and II). Furthermore, it can be derived from the graph of fig. 15 that the presence of the suction element 21 promotes a sudden increase in speed by promoting its maintenance towards the centre of the firing chamber 3 of the kiln 2. While the above-described invention relates in particular to some clearly defined embodiments, it should not be considered as being limited to these embodiments, all variants, modifications or simplifications covered by the appended claims fall within the scope thereof, such as different geometries of the tubular discharge element 10 and/or the guiding outlets 11, 11', 11", the suction element 21, different arrangements (positioning and alignment) of the heating assembly 1 within the device 29, different conveying systems 4, etc.
The apparatus 29 and heating assembly 1 described above have a number of advantages.
The main advantage of the apparatus 29 and heating assembly 1 of the present invention is the reduction of CO of non-renewable raw materials 2 And the emission and consumption generate obvious environmental benefits.
In addition, the use of an electric heater 5 such as described above allows a more precise control of the temperature inside the firing chamber 3, at least in the region with the heating assembly 1 described above, and increases the safety since all safety drawbacks related to combustion are at least partially overcome.
The heating assembly 1 of the present invention enables ceramic articles T to be heated more effectively and uniformly along their entire cross-section, compared to known methods and systems for electrically heating kilns for firing ceramic articles T. This achieves an optimal firing of ceramic articles about 15mm thick, in particular about 10mm thick.
Furthermore, by means of the heating assembly 1 and the device 29 of the present invention, the generation of fumes inside the firing chamber 3 is limited, thus also reducing the risk of particles depositing on the ceramic article T, thus reducing the risk of damaging the article itself.
In addition, the heating assembly 1 of the present invention, due to its geometry and penetration into the firing chamber 3, can be safely installed in place of the standard gas burner structure of kiln 2.
The following aspects of the invention are also provided (alternatively or additionally).
1. A heating assembly (1) for firing ceramic articles (T) mountable in an industrial kiln (2) comprising a firing chamber (3), the heating assembly (1) comprising:
an electric heater (5) comprising a tubular housing (6) having at an end (7) a feed tube (8) for feeding a gas (G) containing ambient air, in particular constituted thereof, into the tubular housing (6), at least one electric heating element extending inside the tubular housing (6) and operable to heat said gas (G); and
a tubular discharge element (10) extending from the tubular housing (6) on the opposite side to the feed tube (8) and configured to receive and flow through the gas (G) exiting the electric heater (5);
-a hollow body (20) coupled to the tubular discharge element (10) and intended to be flowed through by at least a portion of the gas (G) flowing out of the tubular discharge element (10);
-a suction element (21) arranged between the tubular discharge element (10) and the hollow body (20), provided with one or more openings (22) and configured for introducing, in use, at least a portion of the exhaust gases (F) present inside the heating assembly (1), in particular inside the firing chamber (3), into the hollow body (20); and
-a guiding outlet (11 ") for guiding at least a portion of the gas (G) to the outside of the hollow body (20) (in particular the outside of the heating assembly (1), more in particular towards the firing chamber (3) of the kiln (2) in use).
2. The heating assembly (1) according to aspect 1, wherein: the tubular discharge element (10) comprises a first end (12) coupled with a portion (13) of the tubular housing (6), a second end (14) coupled with the hollow body (20) opposite to the first end (12), and a further guiding outlet (11) provided at the second end (14) along a longitudinal symmetry axis (X) of the tubular discharge element (10) for fluidly connecting the tubular discharge element (10) with the hollow body (20); and is also provided with
The hollow body (20) comprises an end (19), and the guiding outlet (11 ") is provided at the end (19) along the longitudinal symmetry axis (X) of the tubular discharge element (10).
3. The heating assembly (1) according to claim 1 or 2, wherein the guiding outlet (11 ") has a through hole with an equivalent diameter of less than or equal to about 60mm, in particular the further guiding outlet (11) has an equivalent diameter of less than about 25 mm.
4. The heating assembly (1) according to any preceding aspect, wherein the suction elements (21) are configured to create a vacuum between the tubular discharge element (10) and the second hollow body (20) to introduce, in use, at least a portion of the exhaust gases (F) present in the firing chamber (3) into the hollow body (20), and the openings (22) extend through the suction elements (21) (e.g. they have an elongated shape and are longitudinally arranged with respect to the tubular discharge element (10) and the second hollow body (20).
5. The heating assembly (1) according to any preceding aspect, wherein the tubular discharge element (10) is coaxial with said hollow body (20) and the suction element (21) comprises a venturi tube.
6. The heating assembly (1) according to any preceding aspect, wherein:
the suction element (21) has a narrow portion (23) and a frustoconical portion (24) delimited by a large base (25) and a small base (26);
the minor base of the frustoconical portion (24) coincides with the narrow portion (23), the major base (25) of the frustoconical portion (24) being coupled to the hollow body (20), in particular the suction element (21) comprising stiffening ribs (27).
7. The heating assembly (1) according to aspect 6, wherein the diameter of the constriction (23) is less than one third of the diameter of the tubular discharge element (10) and the second hollow body (20), in particular the diameter of the constriction (23) ranges from about 10mm (in particular about 20mm, more in particular about 25 mm) to about 60mm (in particular about 40mm, more in particular about 35 mm).
8. The heating assembly (1) according to aspect 6 or 7, wherein the diameter of the tubular discharge element (10) and the second hollow body (20) is between about 30mm (in particular about 40mm, more in particular about 50 mm) and about 200mm (in particular about 120mm, more in particular about 100 mm).
9. An industrial apparatus (29) for firing ceramic articles (T), comprising: -a tunnel kiln (2) provided with at least one side wall (30) and a roof/dome (31) which at least partially define a firing chamber (3) having an inner surface (32) and an outer surface (33); a conveying system (4) configured to move a plurality of ceramic articles (T) along a conveying path (P) within the firing chamber (3); and a heating system (34) configured to heat the firing chamber (3) to fire the plurality of ceramic articles (T) moving through the interior of the firing chamber (3) and obtain a ceramic Product (PC),
Kiln (2) characterized in that said heating system (34) comprises at least one heating assembly (1) according to any of the previous aspects 1-8.
10. Industrial plant (29) according to aspect 9, wherein said heating assembly (1) is mounted with said suction element (21) at least partially inside the firing chamber (3).
11. Industrial plant (29) according to aspects 9 or 10, wherein the (in particular each) heating assembly (1) is mounted such that the electric heater (5) extends at least partially (in particular completely) through (in particular across) a side wall (30) or a roof/dome (31) of the kiln (2) between the inner surface (32) and the outer surface (33), the tubular discharge element (10) extends at least partially (in particular completely) through (in particular across) a side wall (30) or a roof/dome (31) of the kiln (2) between the inner surface (32) and the outer surface (33), and the hollow body (20) extends substantially completely within the firing chamber (3).
12. Industrial plant (29) according to any of the claims 9-11, wherein said heating assembly (1) is mounted such that the tubular discharge element (10) protrudes at least partially into the firing chamber (3).
13. The industrial plant (29) according to any one of aspects 9-12, wherein: the heating system (34) comprises a plurality of heating assemblies (1) arranged in series along the conveying path (P); portions of the plurality of heating assemblies (1) are arranged at the top/dome (31) of the kiln (2); and each heating assembly (1) of said portion of said plurality of heating assemblies (1) is mounted obliquely with respect to the vertical direction and/or with respect to the conveying path (P), in particular at an angle varying between about 0 ° and about 60 ° with respect to the vertical direction and/or at an angle varying between about 0 ° and about 60 ° with respect to the conveying path (P).
14. The industrial plant (29) according to aspect 13, wherein: the firing chamber (3) of the kiln (2) comprises (in particular is divided into) at least one preheating zone, a pre-firing zone immediately downstream of the preheating zone along the determined path (P), a firing zone downstream of the pre-firing zone along the determined path (P) and at least one cooling zone downstream of the firing zone; and the plurality of heating assemblies are arranged at least at the preheating zone (in particular also in the preheating zone) to heat at least the preheating zone of the firing chamber (3) to a temperature of at least about 1100 ℃, in particular at least about 1200 ℃.
15. The industrial plant (29) according to any one of aspects 9-14, wherein: the conveying system (4) comprises a series of ceramic rollers arranged one after the other along the conveying path (P) to define a conveying plane adapted to receive the ceramic articles (T) and move them along the conveying path (P); and at least a portion of the heating assembly (1) is disposed below the conveying path.
Claims (15)
1. A heating assembly (1) for firing ceramic articles (T), mountable in an industrial kiln (2) comprising a firing chamber (3), the heating assembly (1) comprising:
An electric heater (5) comprising a tubular housing (6) having at a first end (7) a feed tube (8) for feeding a gas (G) comprising ambient air into the tubular housing (6), at least one electric heating element extending within the tubular housing (6) and operable to heat the gas (G); and
-a tubular discharge element (10) extending from the tubular housing (6) on the side opposite to the feed tube (8), configured to be flowed through by the gas (G) flowing out of the electric heater (5) and comprising at least one first guiding outlet (11) for guiding at least a portion of the gas (G) towards the outside of the tubular discharge element (10), in particular towards the outside of the heating assembly (1), more in particular towards the firing chamber (3) of the kiln (2) in use, the first guiding outlet (11) having a through hole with an equivalent diameter of less than or equal to about 25 mm.
2. Heating assembly (1) according to claim 1, wherein the tubular discharge element (10) comprises a first end (12) coupled with a portion (13) of the tubular housing (6) and a second end (14) opposite to the first end (12), the at least one first guiding outlet (11) being provided at the second end (14).
3. The heating assembly (1) according to claim 2, wherein:
-said first guiding outlet (11) is arranged along a longitudinal symmetry axis (X) of said tubular discharge element (10); and is also provided with
The second end (14) comprises, in particular defines, a taper (18) for guiding the gas (G) towards the at least one first guiding outlet (11).
4. Heating assembly (1) according to claim 2, wherein the at least one first guiding outlet (11) is provided on a wall (16) of the second end (14).
5. Heating assembly (1) according to any one of claims 2-4, wherein the tubular discharge element (10) comprises at least one second guiding outlet (11 ') for guiding at least a portion of the gas (G) towards the outside of the tubular discharge element (10), the at least one second guiding outlet (11') having a respective through hole with an equivalent diameter of less than or equal to about 25mm and being provided at the second end (14).
6. Heating assembly (1) according to claim 5, wherein the at least one second guiding outlet (11') is provided on a wall portion (16) of the second end portion (14).
7. Heating assembly (1) according to any one of claims 1-4, wherein the tubular discharge element (10) comprises a plurality of second guiding outlets (11 ') provided at least on a wall portion (16) of the second end portion (14) for guiding at least a portion of the gas (G) towards the outside of the tubular discharge element (10), in particular towards the outside of the heating assembly (1), more in particular towards the firing chamber (3) of the kiln (2) in use, each second guiding outlet (11') having a respective through hole with an equivalent diameter of less than or equal to about 25 mm.
8. Heating assembly (1) according to claim 7, wherein a first portion of the second guiding outlets (11 ') comprises corresponding holes having a first equivalent diameter and at least one second portion of the second guiding outlets (11') comprises corresponding holes having a second equivalent diameter different from the first equivalent diameter.
9. A heating assembly (1) according to claim 1 or 2 or 3, comprising a hollow body (20) coupled to the tubular discharge element (10) to be flown through by at least a portion of the gas (G) flowing out of the tubular discharge element (10), a suction element (21) and a further guiding outlet (11 ") for guiding the at least a portion of the gas (G) towards the outside of the hollow body (20), in particular towards the outside of the heating assembly (1), more in particular towards the firing chamber (3) of the kiln (2) in use,
the suction element (21) is arranged between the tubular discharge element (10) and the hollow body (20), is provided with one or more openings (22) and is designed for introducing, in use, at least a portion of the exhaust gases (F) present inside the firing chamber (3) into the hollow body (20).
10. An industrial apparatus (29) for firing ceramic articles (T), comprising: -a tunnel kiln (2) provided with at least one side wall (30) and a roof/dome (31) which at least partially define a firing chamber (3) having an inner surface (32) and an outer surface (33); a conveying system (4) configured to move a plurality of ceramic articles (T) along a conveying path (P) within the firing chamber (3); and a heating system (34) configured to heat the firing chamber (3) to fire the plurality of ceramic articles (T) moving through the interior of the firing chamber (3) and obtain ceramic products,
the kiln (2) is characterized in that the heating system (34) comprises at least one heating assembly (1) according to any of the preceding claims.
11. Industrial plant (29) according to claim 10, wherein said heating system (34) comprises a plurality of heating assemblies (1) arranged in series parallel to said conveying path (P).
12. The industrial plant (29) according to claim 11, wherein: portions of the plurality of heating assemblies (1) are arranged at the top/dome (31) of the kiln (2); each heating assembly (1) of the portions of the plurality of heating assemblies (1) is mounted obliquely with respect to the vertical direction and/or with respect to the conveying path (P), in particular at an angle in the range of about 0 ° to about 60 ° with respect to the vertical direction and/or at an angle in the range of about 0 ° to about 60 ° with respect to the conveying path (P).
13. An industrial plant (29) according to any one of claims 10-12, wherein the/each heating assembly (1) is arranged such that at least a portion of the tubular discharge element (10) protrudes at least partially into the firing chamber (3),
in particular, the tubular discharge element (10) of the heating assembly (1) has a length of at least about 900mm and the/each heating assembly (1) is mounted such that the tubular discharge element (10) protrudes into the firing chamber (3) by a length of at least about 600mm, more particularly the tubular discharge element (10) is configured to laterally span the firing chamber (3).
14. The industrial plant (29) according to any one of claims 10-13, wherein: the firing chamber (3) of the kiln (2) comprises at least one preheating zone, a pre-firing zone immediately downstream of the preheating zone along the conveying path (P), a firing zone downstream of the pre-firing zone along the conveying path (P), and at least one cooling zone downstream of the firing zone along the conveying path (P); and the plurality of heating assemblies (1) are arranged at least at the preheating zone to heat at least the preheating zone to a temperature of at least about 1000 ℃, in particular at least about 1100 ℃.
15. The industrial plant (29) according to any one of claims 10-14, wherein: the conveying system (4) comprises a series of ceramic rollers arranged one after the other along the conveying path (P) to define a conveying plane adapted to receive the ceramic articles (T) and move them along the conveying path (P); and at least a portion of the heating assembly (1) is disposed below the conveying path.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| IT102021000016352 | 2021-06-22 | ||
| IT102021000016334 | 2021-06-22 | ||
| IT102021000016352A IT202100016352A1 (en) | 2021-06-22 | 2021-06-22 | HEATER GROUP AND INDUSTRIAL APPARATUS FOR THE FIRING OF CERAMIC PRODUCTS |
| PCT/IB2022/055733 WO2022269479A1 (en) | 2021-06-22 | 2022-06-21 | Heating assembly and industrial apparatus for the firing of ceramic articles |
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| Publication Number | Publication Date |
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| CN117859033A true CN117859033A (en) | 2024-04-09 |
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| CN202280044449.0A Pending CN117859033A (en) | 2021-06-22 | 2022-06-21 | Heating assembly and industrial equipment for firing ceramic products |
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| IT (1) | IT202100016352A1 (en) |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5134684A (en) * | 1990-05-21 | 1992-07-28 | Gte Products Corporation | Electric air or gas heater utilizing a plurality or serpentine heating elements |
| IT1262340B (en) * | 1993-11-29 | 1996-06-19 | Sacmi Forni Spa | Equipment for rendering the temperature of tiles uniform prior to glazing |
| FI115834B (en) * | 2004-06-09 | 2005-07-29 | Tamglass Ltd Oy | Heating glass panels in heating oven involves heating the glass panel from above and below with convection air or with a combination of convection air and radiation heat, where convection air is heated using heat accumulator |
| CN111433528B (en) | 2017-12-08 | 2021-12-28 | 康泰尔有限公司 | Fluid flow electric heater with stabilizing bracket |
| KR102589424B1 (en) | 2017-12-08 | 2023-10-13 | 칸탈 게엠베하 | Electric fluid flow heater with heating element support member |
| IT201900003481A1 (en) * | 2019-03-11 | 2020-09-11 | Sacmi Forni Spa | APPARATUS AND BURNER FOR COOKING CERAMIC PRODUCTS |
| US20220178584A1 (en) | 2019-03-25 | 2022-06-09 | Kanthal Gmbh | Electric fluid flow heater with heating elements stabilization fins |
-
2021
- 2021-06-22 IT IT102021000016352A patent/IT202100016352A1/en unknown
-
2022
- 2022-06-21 CN CN202280044449.0A patent/CN117859033A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| IT202100016352A1 (en) | 2022-12-22 |
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