WO2009087126A2 - Corps thermorayonnant en céramique, sous forme de plaque, d'un émetteur plan infrarouge - Google Patents

Corps thermorayonnant en céramique, sous forme de plaque, d'un émetteur plan infrarouge Download PDF

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Publication number
WO2009087126A2
WO2009087126A2 PCT/EP2009/050033 EP2009050033W WO2009087126A2 WO 2009087126 A2 WO2009087126 A2 WO 2009087126A2 EP 2009050033 W EP2009050033 W EP 2009050033W WO 2009087126 A2 WO2009087126 A2 WO 2009087126A2
Authority
WO
WIPO (PCT)
Prior art keywords
plate
heat radiating
ceramic heat
radiating body
ceramic
Prior art date
Application number
PCT/EP2009/050033
Other languages
German (de)
English (en)
Other versions
WO2009087126A3 (fr
Inventor
Jörg ADLER
Wieland Beckert
Original Assignee
Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. filed Critical Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
Publication of WO2009087126A2 publication Critical patent/WO2009087126A2/fr
Publication of WO2009087126A3 publication Critical patent/WO2009087126A3/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23D—BURNERS
    • F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
    • F23D14/12—Radiant burners
    • F23D14/14—Radiant burners using screens or perforated plates
    • F23D14/147—Radiant burners using screens or perforated plates with perforated plates as radiation intensifying means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23D—BURNERS
    • F23D2203/00—Gaseous fuel burners
    • F23D2203/10—Flame diffusing means
    • F23D2203/102—Flame diffusing means using perforated plates
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23D—BURNERS
    • F23D2212/00—Burner material specifications
    • F23D2212/10—Burner material specifications ceramic

Definitions

  • the invention relates to the field of materials science and relates to a plate-shaped ceramic heat radiating body of an infrared panel radiator, as it can be used for example in dry systems for drying paper or board webs or for the heating of buildings or halls.
  • infrared panel radiators consist essentially of a burner system with at least one burner plate which burns a fluid-air mixture with a variety of flames and thus heats a previously arranged heat radiating body, the energy as infrared radiation to the opposite Page yields. This infrared radiation then serves for drying or heating.
  • the heat radiating body a variety of contains continuous, acting as a cavity radiator channels, in which the ratio wall surface / cross-sectional area in the flame-free area greater than 10, preferably greater than / equal to 20, is.
  • the heat radiating body is advantageously formed of ceramic.
  • a plate is mounted in front of the combustion zone and heated by the rear side, wherein the exhaust gases are passed through the plate. Overall, this results in a very strong warming of this heat radiation body, which in turn can give off a high thermal radiation to the environment.
  • heat radiating plate different structured materials can be used, for example wire mesh, fiber felts or open-celled Foam ceramic, as described for example in US 3,912,443 A or EP 04 15 008 A1. In some cases, the combustion may still take place in the heat radiating body, as described in principle in EP 06 57 011 A1.
  • heat radiating bodies which are formed as a channel-shaped cavity radiators, i. plates are used which have a plurality of channels with a certain length to diameter ratio.
  • the channels are aligned parallel to the direction of radiation, i. perpendicular to the plate surface, thus acting as a nearly black radiator, i. with a very high emission coefficient.
  • ceramics are particularly suitable for these applications since others, e.g. Metallic materials do not have sufficient high temperature stability and durability.
  • non-oxide ceramics such as silicon nitride or silicon carbide ceramics
  • dense monolithic ceramics possess the highest rigidity (modulus of elasticity), which results in high thermal stresses as a result of locally different thermal expansions.
  • rigidity which is known to be possible through fine pores in the structure.
  • Fine porosity means pore sizes which are significantly smaller than the channel diameter of the heat radiating bodies.
  • the channel diameters of known heat radiating plates are in the mm range, while the fine porosity of ceramic materials is typically below 0.1 mm average pore size.
  • Carbon fiber reinforced SiC materials would have reduced strength after firing of the carbon fibers, but also reduced stiffness, as the burned fibers leave pore channels. Or, special porous nonoxide ceramics containing sufficiently fine porosity, such as recrystallized silicon carbide, could be used.
  • the object of the invention is therefore to provide a plate-shaped ceramic heat radiating body of an infrared panel radiator, which has a high emissivity and at the same time has a high resistance to cracking.
  • the edge sides of the plate which are subject to increased tension during heating, a macroscopic structure with structurings> 0.5 mm, through which the outer edge circumference of the plate relative to the edge circumference of the known plate-shaped ceramic heat radiating body is increased by at least 25%.
  • all four edge sides of the heat radiation body have a macroscopic structure.
  • edge sides have macroscopic structuring over their entire surface.
  • the macroscopic structuring partially correspond to the shape and size of the channels in longitudinal section in the heat radiation body.
  • the outer edge circumference of the plate is increased by 25 to 300%, more advantageously by 90 to 200%.
  • the plate consists of silicon carbide and / or silicon nitride ceramic.
  • the ceramic material of the heat radiating body has an overall porosity of 3-15% and an open porosity of ⁇ 10%. And it is also advantageous when the plate-shaped body is segmented, even more advantageously when the plate-shaped body is divided into half segments, in quarter or third segments.
  • the entire system consisting of gas supply / air mixture, burner plate, radiant heat body, frame / fasteners / brackets is to be understood by an infrared panel radiator.
  • a ceramic plate with channels or of a highly porous material which is heated on the back of the burner plate and emits heat radiation (infrared radiation) to the opposite environment on the front.
  • the high resistance to cracking is achieved by the edge sides of the plate, at least on the sides, which are subject to an increased tensile stress during heating, provided with a macroscopic structure that the outer edge circumference compared to a plate according to the state of the art with smooth edge increase by at least 25%. It should be understood under the edge sides of the plate, the four in terms of area smallest sides of the plate.
  • macroscopic structuring should be understood to mean a geometric design of the edge surfaces which has at least feature sizes of> 0.5 mm and thus differs from the surface enlargement due to roughness increase.
  • the outer peripheral edge of the plate is understood to be the length of the delimiting outer lines of the projection of the plate in the direction of radiation, that is to say the outer delimiting line of the plate.
  • the structuring can be parallel or run obliquely or tapering to the direction of radiation, that is, the extent of different plate sections may also be different.
  • a particular advantage of the solution according to the invention is that the heat radiation body according to the invention in addition to a high resistance to cracking also has a high oxidation stability.
  • the pores are contained in a total amount of 3-15% and the proportion of open pores is less than 10%, advantageously less than 8%.
  • Under total porosity is understood to mean the total volume of pores, which is determined from the ratio of the bulk density and the true density of the ceramic.
  • open porosity is meant the volume of pores accessible from the outside and e.g. is determined by weighing the water absorption. With this small amount of pores, it is ensured that the oxygen transport is so severely limited that the internal oxidation of the plates is very low and the plates achieve a long service life. At the same time, due to the low content, the strength of the plates is only slightly reduced while the elasticity is increased, ie the modulus of elasticity is reduced.
  • Silicon carbide and silicon nitride ceramics in particular, can be used to advantage as non-oxide ceramics, ie ceramics which consist predominantly of silicon carbide or silicon nitride.
  • heat radiating plates have lateral dimensions of about 150x200 mm or 130x180 mm and thicknesses of 5-25 mm. These are, as described in DE 199 01 145 A1, mounted in front of the burner plate or special burner nozzle assemblies and held at the edges of a metal frame, with intermediate strips of a thermal insulation material. Of the Frame is gas-tight connected to the back of the burner, which contains fasteners, gas mixture and gas supply connections.
  • the heat radiation body plates can therefore be segmented and the individual heat radiating body plate segments are used in a radiator.
  • too many and small partitions are counterproductive because they are more difficult to enclose in the support frame.
  • the plates are then placed side by side in the frame.
  • the segmentation reduces the thermo-mechanical stresses in the plates and reduces the susceptibility to cracking.
  • half-finished panels these often tear the two outer panels on the inner sides during heating or cooling on the inner sides and on the one-third or quarter panels.
  • the susceptibility to cracking completely disappears if at least one of the outer edge sides of the plates is geometrically designed such that they have a resistance to a smooth edge of the plate has at least 25% increased circumference and this edge side is used on the most crack-prone side.
  • all sides of the plates can be provided with a structured edge, since this avoids the risk of a wrong position when inserting the plates in the frame.
  • the structuring leads to a significantly further increase in the circumference, than 25%; e.g. has a 30, 50, 90%, up to 300% larger circumference than straight, unstructured plate sides.
  • the macroscopic structures are produced by guiding the channels or large pores of the heat radiation body beyond the edge of the plate, whereby, for example, channels with round cross sections and uniform arrangement, the channels each have semicircular recesses in cross section. If the channels have a different cross-sectional shape or arrangement, the recesses of the structuring also each have a different shape, wherein in these cases, the recesses of the structuring in cross-section always partially have the cross-sectional shape of the channels. When using a large pore ceramic material for the heat radiation body, the edges are completely irregular in cross-sectional and surface shape.
  • edges by special edge processing in each desired manner, on the one hand allows the largest possible increase in the edge circumference, on the other hand makes the plate still implementable in the existing brackets or devices.
  • Fig. 1 a heat radiation body plate (1) according to the prior art with 180x130x10 mm in plan view or as a projection in the emission direction of Surface 180x130 made of a ceramic (2) with continuous cylindrical channels (3) with diameters of 4 mm and lengths of 10 mm parallel to the direction of radiation.
  • Figure 2 in the projection of three identical heat radiating body panel segments (4) according to the prior art with dimensions of 60x130x10 mm and with straight edge circumference, which side by side arranged a heat radiating body plate 180x130x10 mm. (27) shows areas on the inner sides of the segments where cracking occurs during rapid heating.
  • Fig. 3 in the projection of an inventive heat radiating plate segment (5) with the dimensions 60x130x10 mm, in which all 4 sides (6) have a structured edge circumference, which is a total of 38% greater than that of the segments (4).
  • Fig. 4 in the projection of an inventive heat radiating plate segment (7) with the dimensions 60x130x10 mm, in which one side (9) has a structured edge circumference, which is compared to the unstructured edge periphery (8) increased by 30%.
  • Fig. 5 in the projection another possibility of embodiment of a heat radiating body panel segment (10) according to the invention with the dimensions 60x130x10 mm, in which one side (12) has a structured edge circumference, which is compared to the unstructured edge periphery (11) increased by 180%.
  • Fig. 6 in the projection another possibility of the embodiment of a primallöplattensegmentes (13) according to the invention with the dimensions 60x130x10 mm, in which one side (15) has a structured edge circumference, which is compared to the unstructured edge periphery (14) enlarged by 50%.
  • Fig. 7 in the projection another possibility of the embodiment of a heat radiating body panel segment (16) according to the invention with the Dimensions 60x130x10 mm, which contains prismatic channels, which form hexagons in cross section and in which one side (18) has a structured edge circumference, which is compared to the unstructured edge circumference increased by 28%.
  • Fig. 8 in the projection another possibility of the embodiment of a heat radiating body plate segment (19) according to the invention with the dimensions 60x130x10 mm, which contains prismatic channels which form in cross-section squares 4x4 mm and in which one side (21) has a structured edge circumference, the compared to the unstructured edge circumference (20) is increased by 95%.
  • Fig. 10 in the projection of a three segments (24) composite heat radiating plate according to the invention with the dimensions 180x130x10mm.
  • the segments (24) correspond to the variant (5) described in FIG.
  • 60x130x10 mm heat radiating plate segments with 372 continuous, uniformly arranged, parallel cylindrical channels with a diameter of 4 mm and a length of 10 mm, all perpendicular to the plate surface 60x130, are made by hot casting a suspension of silicon carbide ceramic powder and additives, with subsequent debinding and pressureless sintering.
  • the SiC ceramic is sintered to have a 7% open porosity determined by water uptake, which is formed from small, isolated pores having a mean size of 8 ⁇ m (Determination by image evaluation on the ceramographic grinding). The total porosity is 13%.
  • the outer 4 narrow sides of the plates are processed after sintering so that no smooth outer edges arise, but that these edge sides are provided with many repeated structuring, which in detail in the form of cutouts of cylindrical channels with diameters of 4 mm; the longitudinal sides have 16 such halved cylindrical recesses, while the shorter end faces each have 12.5 of these semi-cylindrical recesses.
  • the plan view that is, in the projection perpendicular to the surface 60x130 mm results in the image shown in Fig. 3, in which all 4 sides (6) have a structured edge circumference, which has a total circumference of 525 mm, which is 38% larger than a segment with smooth edges (circumference 380 mm).
  • Each of these three heat radiating plate segments according to the invention with the dimensions 60x130x10 mm are combined to a heat radiating plate 130x180x10 mm, as in the plan view, that is, as a projection on the surface 130x180 in Fig. 10.
  • This heat radiating plate is installed in an infrared surface radiator, as described in WO 0042356, Figure 1.
  • This burner is experimentally heated with propane gas-air mixture at a gas pressure of 190000 Pa and a total power of 11 kW. After ignition, the plates are heated within a few seconds to a temperature of 1200 0 C. By interrupting the gas supply, the burner extinguishes and the plates cool down within a few minutes. This start-stop cycle is repeated 10 times without cracks appearing on the heat radiating plate segments. In a continuous operation test of 1000 h at a constant temperature of 1200 0 C, a mass gain due to oxidation of 1, 2% is recorded, after 10,000 h of 3.9%. A critical loss of strength due to oxidation is expected only at a mass increase of 5%. Comparative Example 2:
  • Heat radiating plate segments with the dimensions 60x130x10 are prepared analogously to Example 1, with the difference that they have a smooth edge without the structuring according to the invention and thus correspond to the heat radiating body plate segments according to the prior art. Three of these heat radiating plate segments with the dimensions 60x130x10 mm are combined to a heat radiating plate 130x180x10 mm, as in the plan view, that is, as a projection on the surface 130x180 shown in Figure 2. This heat radiating body plate is tested analogously as in Example 1. Even at the first heating crack on the inner side of the two outer segments ((27) in Figure 2) are recorded, which continue to grow in further cycling and lead to the rupture of individual parts of the plates to the point of complete breakage.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Ceramic Products (AREA)
  • Drying Of Solid Materials (AREA)

Abstract

L'invention se rapporte au domaine des sciences des matériaux et concerne un corps thermorayonnant en céramique, sous forme de plaque, d'un émetteur plan infrarouge, pouvant être utilisé, par exemple, dans des systèmes de séchage pour le séchage de bandes de papier ou de carton ou le chauffage de bâtiments ou de salles. Le but de l'invention est de fournir un corps thermorayonnant en céramique, sous forme de plaque, d'un émetteur plan infrarouge présentant à la fois une haute émissivité et une haute résistance à la fissuration. A cet effet, l'invention concerne un corps thermorayonnant en céramique, sous forme de plaque, d'un émetteur plan infrarouge, plaque dont au moins les faces latérales, qui sont soumises à un effort de traction accru lors de l'échauffement, présentent une structuration macroscopique à structurations > 0,5 mm, grâce auxquelles le périmètre extérieur de la plaque est augmenté d'au moins 25 % par rapport au périmètre des corps thermorayonnants en céramique, sous forme de plaque, connus.
PCT/EP2009/050033 2008-01-07 2009-01-05 Corps thermorayonnant en céramique, sous forme de plaque, d'un émetteur plan infrarouge WO2009087126A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102008000010A DE102008000010B4 (de) 2008-01-07 2008-01-07 Plattenförmiger keramischer Wärmestrahlkörper eines Infrarot-Flächenstrahlers
DE102008000010.8 2008-01-07

Publications (2)

Publication Number Publication Date
WO2009087126A2 true WO2009087126A2 (fr) 2009-07-16
WO2009087126A3 WO2009087126A3 (fr) 2011-03-10

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PCT/EP2009/050033 WO2009087126A2 (fr) 2008-01-07 2009-01-05 Corps thermorayonnant en céramique, sous forme de plaque, d'un émetteur plan infrarouge

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WO (1) WO2009087126A2 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20120193452A1 (en) * 2009-12-11 2012-08-02 Nv Bekaert Sa Burner with low porosity burner deck
DE102010017239B4 (de) * 2010-06-04 2017-09-21 Océ Printing Systems GmbH & Co. KG Vorrichtung und Verfahren zum Fixieren von Druckbildern auf einem Aufzeichnungsträger

Citations (4)

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Publication number Priority date Publication date Assignee Title
GB976850A (en) * 1963-11-26 1964-12-02 Moffats Ltd Improvements in or relating to gas burners
WO2003069225A1 (fr) * 2002-02-12 2003-08-21 Voith Paper Patent Gmbh Emetteur de rayons infrarouges sous la forme d'un emetteur plan
US20040132607A1 (en) * 2003-01-08 2004-07-08 3M Innovative Properties Company Ceramic fiber composite and method for making the same
EP1693618A2 (fr) * 2005-01-21 2006-08-23 Deutsches Zentrum für Luft- und Raumfahrt e.V. Corps poreux pour un brûleur poreux, procédé de fabrication d'un corps poreux pour un brûleur poreux et brûleur poreux

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DE466586C (de) * 1928-10-09 Wilhelm Ruppmann Fa Brenner
DE464692C (de) * 1928-08-23 Wilhelm Ruppmann Fa Brenner mit hintereinanderliegenden Lochplatten
US1419499A (en) * 1921-09-03 1922-06-13 Carl R Hartman Vegetable cutter and crusher
US2103365A (en) * 1934-03-01 1937-12-28 Selas Company Gas burner
GB1082823A (en) * 1964-08-26 1967-09-13 Minnesota Mining & Mfg Radiant gas burner assembly
GB1439767A (en) * 1972-09-25 1976-06-16 Foseco Int Radiant gas burners
JPS5546361A (en) * 1978-09-29 1980-04-01 Rinnai Corp Gas infrared ray radiation combustion plate
DE3926699A1 (de) * 1989-08-12 1991-02-14 Kloeckner Waermetechnik Gasbrenner
DE4322109C2 (de) * 1993-07-02 2001-02-22 Franz Durst Brenner für ein Gas/Luft-Gemisch
DE4335707C2 (de) * 1993-10-20 1995-08-10 Didier Werke Ag Verkleidung einer Brennkammerwand
DE19901145A1 (de) * 1999-01-14 2000-07-20 Krieger Gmbh & Co Kg Als Flächenstrahler ausgebildeter Infrarot-Strahler
EP1715250A1 (fr) * 2005-04-19 2006-10-25 Siemens Aktiengesellschaft Elément de bouclier thermique pour revêtir la paroi d'une chambre de combustion, chambre de combustion et turbine à gaz

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB976850A (en) * 1963-11-26 1964-12-02 Moffats Ltd Improvements in or relating to gas burners
WO2003069225A1 (fr) * 2002-02-12 2003-08-21 Voith Paper Patent Gmbh Emetteur de rayons infrarouges sous la forme d'un emetteur plan
US20040132607A1 (en) * 2003-01-08 2004-07-08 3M Innovative Properties Company Ceramic fiber composite and method for making the same
EP1693618A2 (fr) * 2005-01-21 2006-08-23 Deutsches Zentrum für Luft- und Raumfahrt e.V. Corps poreux pour un brûleur poreux, procédé de fabrication d'un corps poreux pour un brûleur poreux et brûleur poreux

Also Published As

Publication number Publication date
WO2009087126A3 (fr) 2011-03-10
DE102008000010A1 (de) 2009-07-09
DE102008000010B4 (de) 2010-10-14

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