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
  • F23D14/46—Details, e.g. noise reduction 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
  • F23D2203/101—Flame diffusing means characterised by surface shape
  • F23D2203/1012—Flame diffusing means characterised by surface shape tubular
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23D—BURNERS
  • F23D2210/00—Noise abatement
• • 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
  • F23D2900/00003—Fuel or fuel-air mixtures flow distribution devices upstream of the outlet

Definitions

• the invention relates to a premix gas burner with a cylindrical or frusto- conical shape burner deck.
• Premix gas burners of cylindrical or frusto-conical shape have a burner plate (or burner surface or burner deck) of cylindrical or frusto-conical shape around a mixing chamber.
• the premixed gas and air mixture is supplied together via an inlet and gets further mixed in a mixing chamber lying inside the burner deck. From the mixing chamber the gas and air is supplied to the burner deck through holes in the burner deck. The flames are produced on the external surface of the burner deck (or burner plate or burner surface).
• the process of gas being mixed with air immediately followed by the heavy burner reaction and flames gives rise to waves travelling in the direction of the gas-air mixture and to waves travelling back from the burner plate in the opposite direction.
• a resonance phenomenon may be created. Inside the volume of the mixing chamber and the volume of the burner plate standing waves are present. These standing waves generate noise and are the cause of an incomplete burner reaction.
• EP-A-1087180 solves this problem of noise and incomplete burner
• WO2009/1 12909A2 shows a burner comprising an inlet for the premix gas to be burnt.
• the inlet a channelling element, can be surrounded by one or more holes in the plate around the tubular element through which further premix gas is flowing into the mixing chamber.
• this inlet system is not in all circumstances giving satisfactorily noise reduction.
• the burner deck is positioned around a mixing chamber.
• the burner deck can have a cylindrical shape or a frusto-conical shape.
• the burner has an entry for introducing premixed gas and air mixture into the mixing chamber.
• a primary axial flow element, the so-called anti-noise tube is inserted in the entry and guides part of the premixed gas and air mixture into a mixing chamber.
• This primary axial flow element has a first length L-i , in the direction of the flow of the premixed gas and air mixture and a first diameter D-i , in a plane perpendicular to the direction of the flow of the premixed gas and air mixture.
• This primary axial flow element offers little resistance in the direction of the flow of the premixed gas and air mixture and offers more resistance in the opposite direction, so that the likelihood for creation of standing waves is decreased.
• At least one secondary axial flow element is also positioned in the entry parallel to the primary axial flow element.
• the secondary axial flow element has a second length L 2 , in the direction of the flow of the premixed gas and air mixture and a second diameter D 2 , in a plane perpendicular to the direction of the gas and air.
• the second length L 2 is different from the first length l_i and the second diameter D 2 is smaller than the first diameter D-i .
• Both the primary axial flow element and the secondary axial flow elements are introducing premixed gas and air mixture into the mixing chamber where further mixing occurs and distribution to the burner plate on which outer surface combustions occurs.
• the secondary axial flow element or elements offer little resistance in the direction of the flow of the premixed gas and air mixture and offer more resistance in the opposite direction. These secondary axial flow elements, taken in isolation, thus also decrease the likelihood of generation of standing waves.
• the geometry of the secondary axial flow elements is different from the geometry of the first axial element, the combined action of both the first axial flow element and the secondary axial flow element or elements decreases the likelihood of the creation of standing waves over a wider frequency spectrum. So the invention particularly avoids thermo acoustic instabilities.
• the secondary axial flow elements improve the cooling of the burner plate or burner deck through the introduction of the moving premixed gas and air mixture.
• the secondary axial flow elements preferably have a tubular or frusto-conical shape, which improves the heat transfer e.g. compared to through holes in a plate.
• the flow of the premixed gas-air mixture through the primary axial flow element and the secondary axial flow element or elements is an
• the premixed gas air mixture is entered in the primary axial flow element and in the secondary axial flow element via one supply, which means that the premixed gas air mixture is entering at the same pressure the primary axial flow element and the secondary axial flow elements.
• the second length L 2 is preferably smaller than the first length L-i .
• Preferably more than one secondary axial flow element is provided.
• these secondary axial flow elements may be arranged in a circle around the primary axial flow element.
• the primary axial flow element and the secondary axial flow element or elements are arranged on a single-piece flange, e.g. of plate thickness between 0.5 and 1 .5 mm, e.g. of plate thickness 1 mm. This avoids the welding operation and reduces the number of parts.
• Figure 1 shows a perspective view of a flange with primary and secondary axial flow elements to be used in a premix gas burner according to the invention
• Figure 2 shows a bottom view of a flange with primary and secondary axial flow elements to be used in a premix gas burner according to the invention
• Figure 3 shows a cross-section of a premix gas burner according to the invention.
• a premix gas burner 10 comprises a burner plate or burner deck 12.
• the burner plate (burner deck) 12 is of a cylindrical type.
• This burner plate 12 is preferably made out of metal, e.g. steel, which is welded together and is surrounding the mixing chamber.
• the burner plate 12 is provided with perforations which show a potentially varying pattern over the height of the burner 10.
• a closed cover plate 14 is provided at the top of the premix gas burner 10.
• the burner plate 12 and the closed cover plate 14 surround a mixing chamber.
• a bottom flange 16 is provided at the bottom or entry side of the premix gas burner 10.
• the circular bottom flange 16 is provided with a first vertical partition 18, which fits inside the lower part of the burner plate 12. Going to the centre or middle of the bottom flange 16, a horizontal annular part 20 houses a plurality of secondary air flow elements 22, which are in this example of tubular shape. Further to the centre or middle of the bottom flange 16, a second vertical partition forms a primary axial flow element 26. Premixed gas air mixture is introduced into the mixing chamber of the burner via the secondary flow elements 22 and via the primary air flow element 26 via one single supply and hence at the same pressure.
• Di may range between 20 mm and 38 mm
• l_i may range
• D 2 may range between 0.5 mm and 4.0 mm, e.g. between 1 .0 mm and 3.0 mm
• L 2 may range between 0.5 mm and 6.0 mm, e.g. between 1 .5 mm and 5.0 mm, and preferably between 2.5 and 5 mm.

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Gas Burners (AREA)

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Applications Claiming Priority (3)

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• 2011
  • 2011-11-23 EP EP11790587.7A patent/EP2643635A1/en not_active Withdrawn
  • 2011-11-23 CN CN2011800561814A patent/CN103228989A/zh active Pending
  • 2011-11-23 WO PCT/EP2011/070805 patent/WO2012069534A1/en active Application Filing

Non-Patent Citations (2)

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