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
  • F23D14/16—Radiant burners using permeable blocks
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23D—BURNERS
  • F23D2203/00—Gaseous fuel burners
  • F23D2203/10—Flame diffusing means
  • F23D2203/105—Porous 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
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23D—BURNERS
  • F23D2900/00—Special features of, or arrangements for burners using fluid fuels or solid fuels suspended in a carrier gas
  • F23D2900/03082—Wick made of specific material, e.g. ceramic

Definitions

• the present invention relates to a ceramic burner plate for infrared radiators, which has as its main component a lithium silicate.
• Ceramic burner plates are used in infrared radiators in which a gas-oxygen mixture is burned on the surface of the ceramic plates for heat generation. This creates infrared radiation, which is used for heat generation.
• infrared heaters over conventional heating systems is, on the one hand, that infrared radiators can dissipate heat almost lossless, since no carrier medium is needed for energy transport, but the heat in the form of infrared radiation is emitted, on the other hand draft phenomena, as they occur in conventional combustion systems, can be avoided ,
• radiators are heated directly by an atmospheric burner and operated with a suitable fuel such as natural gas or LPG.
• a suitable fuel such as natural gas or LPG.
• they are installed on the wall or ceiling and are used primarily for heating high or poorly insulated rooms, their property as an infrared radiation source having an advantageous effect, since primarily the illuminated surfaces are heated and only secondarily, the ambient air is heated.
• the name Hellstrahler is attributed to the visible combustion of a fuel-air mixture on the ceramic burner plate, which thereby anneals.
• the ceramic burner plates can reach temperatures of 950 ° C and more.
• a dark radiator also generate the heat by burning an oxygen-fuel gas mixture, but in contrast to the light radiators in a closed jet pipe.
• the hot gases generated by the combustion heat the surface of the jet pipe, which emits the heat predominantly as radiation.
• a dark radiator consists essentially of a burner plate having a burner, a fan, a radiation tube and a reflector disposed above.
• the fan is arranged in front of the burner, so that air is pressed into the system. As a result, a laminar flame distribution is achieved, which leads to a more uniform heating of the jet pipe.
• the fan is not exposed to the hot exhaust gases in this construction, which significantly reduces the mechanical stress on the fan.
• the radiation yield of modern dark radiators can be up to 65%.
• Burner plates for infrared radiators are generally known in the art. So revealed the DE 21 63 498 a burner plate for infrared radiator with mounted on the radiation side wells and with for supplying the fuel-air mixture from the mixture side of the plate to the emission side extending, mutually parallel combustion channels, of which at least one concentrically arranged in the bottom of the recess and others on the Side of the recess and are distributed to the surfaces located between the wells, which is characterized in that the combustion channels are distributed over the recesses and the material webs therebetween such that the resulting flames so evenly on the side surfaces of the recess on the one hand and the intervening On the other hand material webs act, that the resulting temperature in the wells of the web surface resulting temperature is approximately equal.
• This embodiment of the burner plate represents the standard today used embodiment of the burner plate.
• the DE 94 02 556 U1 discloses a ceramic gas burner plate which is conventionally made of cordierite. It can be produced synthetically from clay, steatite and alumina or alumina as magnesium aluminum silicate become.
• German patent application DE 44 45 426 A1 discloses a radiant burner with a gas-permeable burner plate, which burner plate may be made of fiber materials such as silicon carbide fibers in the gas-permeable regions, whereas the gas-impermeable regions are formed of alumina or cordierite-based ceramics.
• the DE 40 41 061 A1 discloses a burner plate.
• the burner plate disclosed here is particularly suitable for flat burners and is based on an aluminum titanate ceramic.
• an Al 2 TiO 5 ceramic is disclosed as being suitable for the production of corresponding burner plates.
• the DE 91 16 829 discloses a burner plate for radiant burners, which consists predominantly of alumina.
• the aluminum silicates used to produce the burner plates known from the prior art have a relatively low firing temperature of at most 1000 ° C., which is in the range of the operating temperature of the infrared radiators. This leads to a heavy load on the burner plates.
• magnesium silicates such as cordierite have a significantly higher firing temperature of 1300 ° C, but these must either be fired from ground and mixed raw materials at high temperatures or burned masses must be ground, mixed into the burner plate mass and then at low temperature finished burned. In addition to a higher load on the material, this leads to a significantly higher outlay in the production of the burner plates.
• the object of the present invention is to specify a ceramic burner plate which is improved with respect to its material.
• a ceramic burner plate for infrared radiators which is characterized in that the burner plate has a lithium oxide content of between 0.63 wt .-% and 7.6 wt .-%.
• a lithium oxide content in the range between 0.63 wt .-% and 7.6 wt .-% corresponds to a content of lithium silicate in the ceramic composition for the production of the burner plate of 15% assuming a lithium oxide content in the lithium silicate of 4.2% and 100% of a lithium silicate with an assumed lithium oxide content of 7.6 wt .-%.
• lithium silicates such as silicates of the feldspar-type petalite the general formula Li 2 O * Al 2 O 3 * 2, or spodumene 8SiO the general formula Li 2 O * Al 2 O 3 4SiO 2 * can of course.
• lithium minerals such as lepidolite or synthetic lithium carbonates can be used.
• the burner plates according to the invention may contain as further constituents at least one oxide of the group consisting of Al 2 O 3 , SiO 2 , Fe 2 O 3 , TiO 2 , CaO, MgO, K 2 O, Na 2 O, Mn 3 O 4 , Cr 2 O 3 , P 2 O 5 or ZrO 2 .
• the ceramic burner plates according to the invention can have the abovementioned oxides in the amounts stated in Table 1 below.
• Table 1 Al 2 O 3 22.0-35.0% SiO 2 55.0-70.0% Fe 2 O 3 0,00-8,00% TiO 2 0,00-4,00% CaO 0,00-4,00% MgO 0,00-10,0% K 2 O 0,00-2,00% Na 2 O 0,00-2,00% Mn 3 O 4 0,00-8,00% Cr 2 O 3 0,00-2,00% P 2 O 3 0.00-1.00% ZrO 2 0.00-5.00% Li 2 O 1,00-7,60%
• these oxides are added to the material for producing the ceramic burner plate in the form of suitable minerals.
• Bindetones with a high plastic clay mineral content and a high Al 2 O 3 content can be used according to the invention. Bindetones with an Al 2 O 3 content> 30% by weight are preferably used.
• Bindetones having a low alkali content ⁇ 1.5% by weight are advantageously used in accordance with the invention.
• the proportion of free quartz in the advantageously used binding clays is ⁇ 8 wt .-%.
• magnesium silicates can be added to the material for producing the ceramic burner plate.
• a mixture of the aforementioned oxide-containing materials is added to the material for producing the ceramic burner plate.
• the ceramic burner plates according to the invention exhibit a continuous capacity at temperatures> 1100 ° C.
• the ceramic burner plates according to the invention are not brittle like the plates known from the prior art, but soft, which significantly simplifies their processing.
• the burner plates according to the invention exhibit an extremely low thermal expansion, which reduces their mechanical load and, moreover, simplifies the secure bonding of the plates at different temperatures to carrier systems.
• the plates of the invention show a high thermal shock resistance and are extremely durable.
• the mechanical hardness of the ceramic burner plates according to the invention can be controlled via the firing temperature in relatively large areas.
• the ceramic burner plates according to the invention show, for example, at a firing temperature ⁇ 1025 ° C, a standard breaking strength of 16 - 18 kg. An increase in the firing temperature increases the breaking strength.
• a ceramic burner plate according to the invention for example, at a firing temperature of 1100 ° C, a standard breaking strength of up to 22 kg. By increasing the firing temperature, the breaking strength can be further increased to well over 24 kg.
• a ceramic burner plate according to the invention with a density of 1.2 g / cm 3 and a porosity of 54% shows the following composition.
• ceramic plate Al 2 O 3 26,17 SiO 2 65.89 Fe 2 O 3 1.36 TiO 2 1.05 CaO 0.47 MgO 4.00 K 2 O 0.66 Na 2 O 0.29 Mn 3 O 4 0.03 Cr 2 O 3 ⁇ 0.01 P 2 O 5 0.08 ZrO 2 ⁇ 0.01 Li 2 O-dried sample 1.49 AAS Weight change d. Annealing (1025 ° C) -0.03
• the thermal shock resistance TWB (1-3) of the ceramic burner plate according to the invention was 1, wherein the thermal shock resistance is determined by means of a quenching test.
• a TWB value of 1 correlates with a thermal expansion of the ceramic plate of about 0.2 at 950 ° C.

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• 2007
  • 2007-07-13 EP EP07013787A patent/EP2014980A1/fr not_active Withdrawn
• 2008
  • 2008-07-11 CA CA002637506A patent/CA2637506A1/fr not_active Abandoned
  • 2008-07-11 US US12/171,374 patent/US20090029306A1/en not_active Abandoned
  • 2008-07-11 JP JP2008181487A patent/JP2009018988A/ja active Pending
  • 2008-07-14 CN CNA2008101379823A patent/CN101413665A/zh active Pending

Patent Citations (5)

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