CYLINDRICAL GAS PREMIX BURNER

Abstract

A cylindrical gas premix burner comprises a cylindrical burner deck onto which the flames are stabilized when the burner is in use; a mixing chamber inside the cylindrical burner deck; an inlet device mounted perpendicularly to the axial direction of the cylindrical burner deck for the supply of premix gas into the mixing chamber; and an end cap closing off the mixing chamber at the side opposite to the side where the inlet device is provided. The inlet device comprises a perforated metal plate. The perforations in the perforated metal plate are provided for the supply of premix gas into the mixing chamber. The perforated metal plate is dome shaped; such that perforations in the perforated metal plate are located at different height levels from the base of the cylindrical burner deck.

Claims

1-15. (canceled)

16. Cylindrical gas premix burner, comprising a cylindrical burner deck onto which the flames are stabilized when the burner is in use; a mixing chamber inside the cylindrical burner deck; an inlet device mounted perpendicularly to the axial direction of the cylindrical burner deck, for the supply of premix gas into the mixing chamber; and an end cap closing off the mixing chamber at the side opposite to the side where the inlet device is provided; wherein the inlet device comprises a perforated metal plate; wherein the perforations in the perforated metal plate are provided for the supply of premix gas into the mixing chamber; wherein the perforated metal plate is dome shaped; such that perforations in the perforated metal plate are located at different height levels from the base of the cylindrical burner deck.

17. Cylindrical gas premix burner as in claim 16, wherein the dome shape of the perforated metal plate is provided by deep drawing of a perforated metal plate.

18. Cylindrical gas premix burner as in claim 16, wherein the inlet device comprises a flange for mounting the inlet device into the burner.

19. Cylindrical gas premix burner as in claim 16, wherein the part of the perforated metal plate at the central axis of the cylindrical burner deck is double curved.

20. Cylindrical gas premix burner as in claim 16, wherein the perforated metal plate comprises a flat central section provided with perforations.

21. Cylindrical gas premix burner as in claim 16, wherein the perforated metal plate comprises a spherical segment.

22. Gas premix burner as in claim 16, wherein the inlet device comprises a surface for mounting the burner into a heating appliance; wherein the dome shape of the perforated metal plate extends into the inside of the mixing chamber; wherein the largest distance P from the surface of the dome shape of the perforated metal plate to the plane of the surface of the inlet device for mounting the burner into a heating appliance is at least 0.25 times the internal diameter D of the cylindrical burner deck.

23. Gas premix burner as in claim 16, wherein the cylindrical burner deck comprises at its end where the inlet device is provided a blind zone onto which no combustion occurs when the burner is in use; wherein the blind zone has a length L1 measured from the end of the cylindrical burner deck where the inlet device is provided; wherein the inlet device comprises a surface for mounting the burner into a heating appliance; wherein the dome shape of the perforated metal plate extends into the inside of the mixing chamber; wherein the largest distance P from the surface of the dome shape of the perforated metal plate to the plane of the surface of the inlet device for mounting the burner into a heating appliance is at least 0.75 times, even more preferably at least 0.9 times the length L1 of the blind zone.

24. Cylindrical gas premix burner as in claim 16, wherein the cylindrical burner deck has an L/D ratio of more than 3; wherein L is the axial length of the burner deck and D is the internal diameter of the cylindrical burner deck.

25. Cylindrical gas premix burner as in claim 16, wherein the cylindrical burner deck comprises a perforated metal sheet or a steel wire mesh.

26. Cylindrical gas premix burner as in claim 25, wherein the cylindrical burner deck comprises a perforated metal sheet or a steel wire mesh onto which the flames are stabilized when the burner is in use.

27. Cylindrical gas premix burner as in claim 16, wherein the cylindrical burner deck comprises a fiber based burner deck onto which flames are stabilized when the burner is in use.

28. Cylindrical gas premix burner as in claim 16, wherein the burner is provided so that in use of the burner, the premix gas flows from the inlet device through the cylindrical burner deck without further passing a gas diffusing device.

29. Cylindrical gas premix burner as in claim 16, wherein the mixing chamber comprises a diffuser, wherein the diffuser is an open pore cylindrical object.

30. Cylindrical gas premix burner as in claim 16, wherein an ignition pen and/or a flame sensing pen is provided; and wherein the ignition pen and/or the flame sensing pen are provided at the side of the burner where the inlet device is provided.

Description

BRIEF DESCRIPTION OF FIGURES IN THE DRAWINGS

[0032] FIG. 1 shows an exploded view of a gas premix burner according to the invention.

[0033] FIGS. 2 and 3 show inlet devices that can be used in the invention.

[0034] FIG. 4 shows a gas premix burner according to the invention

MODE(S) FOR CARRYING OUT THE INVENTION

[0035] FIG. 1 shows an exploded view of a premix gas burner 100 according to the invention. The gas premix burner comprises a cylindrical burner deck 110. The cylindrical burner deck comprises at its end where the inlet device is provided a blind zone onto which no combustion occurs when the burner is in use; the blind zone has a length L1 measured from the end of the cylindrical burner deck where the inlet device is provided. An exemplary burner has a length L 600 mm and an internal diameter D 100 mm. Another example of such burner has a length L 300 mm and an internal diameter D 70 mm. Yet another example of such burner has a length L 450 mm and an internal diameter D 80 mm. The cylindrical burner deck 110 encloses a mixing chamber. The cylindrical burner deck consists out of a metal sheet that has perforations 114 in the form of circular holes and/or slits. The perforated metal sheet has been bent into a cylindrical shape and welded at its edges 112. The gas premix burner 100 further comprises an inlet device 120, mounted perpendicularly to the axial direction of the cylindrical burner deck 110. The inlet device 120 comprises a flange 130 for mounting the inlet device 120 into the burner 100. The flange 130 can also be used to mount the burner into a heating appliance. The inlet device 120 comprises a perforated metal plate 145; the perforations 147 of which are provided for the supply of premix gas into the mixing chamber. The perforated metal plate 145 is dome shaped, such that perforations in the perforated metal plate 145 are located at different height levels from the base of the cylindrical burner deck. In the example, the dome shape extends into the mixing chamber when the inlet device 120 is mounted in the burner 100. The dome shape of the perforated metal plate 145 is provided by deep drawing of a perforated metal plate. When using the burner, premix gas is fed through the perforations 147 of the dome shaped perforated plate 145 of the inlet device 120 into the mixing chamber. The burner 100 comprises an end cap 180, which closes off the mixing chamber at the side opposite to the side where the inlet device is provided. The exemplary burner 100 of FIG. 1 is provided such that in use of the burner, the premix gas flows from the inlet device through the cylindrical burner deck without further passing a gas diffusing device.

[0036] FIGS. 2 and 3 show cross sections of inlet devices that can be used in the invention. The cross sections are taken along a plane through the axis of symmetry of the gas premix burner. Preferably, the shape of the inlet devices is axisymmetric around the axis of symmetry of the gas premix burner.

[0037] FIG. 2 shows an inlet device 220 comprising a flange 230 onto which a perforated metal plate 240 is attached, e.g. by means of welding. The perforated metal plate 240 is shaped into a dome. The largest distance P from the surface of the curved shape of the perforated metal plate 240 to the plane of the surface of the flange 230 for mounting the burner into a heating is e.g. 22 mm for a burner with cylindrical burner deck with internal diameter 80 mm.

[0038] FIG. 3 shows an inlet device 320 comprising a flange 330 onto which a perforated metal plate 340, is attached, e.g. via welding. The perforated metal plate 340 is shaped into a curved segment 342 and a flat top section 344. The largest distance P from the surface of the flat top section of the perforated metal plate 344 to the plane of the surface of the flange 330 for mounting the burner into a heating appliance is e.g. 18 mm for a burner with cylindrical burner deck with internal diameter 80 mm. It is also possible that the curved section 342 and the flat top section 344 exist out of different perforated metal plates that are connected to each other, e.g. by means of welding; in such embodiments the perforated metal plates building the curved section and building the flat top section can have the same design or can be different in design (e.g. in density and/or in diameter of perforations).

The perforated metal plate comprises a flat central section provided with perforations. In such embodiment, the curved segment 342 can be a spherical segment.

[0039] FIG. 4 shows a premix gas burner 400 according to the invention. The gas premix burner comprises a cylindrical burner deck 410. An exemplary burner has a length L of 600 mm and an internal diameter D of 100 mm. The cylindrical burner deck 410 encloses a mixing chamber. The cylindrical burner deck consists out of a metal sheet that has perforations 414 in the form of circular holes and/or slits. The perforated metal sheet has been bent into a cylindrical shape and welded at its edges 412. The gas premix burner 400 further comprises an inlet device 420, mounted perpendicularly to the axial direction of the cylindrical burner deck 410. The inlet device 420 comprises a flange 430 for mounting the inlet device 420 into the burner 400. The flange 430 can be used to mount the burner to a supporting structure in a heat exchanger via the holes 432 in the flanges and nuts and bolts. The inlet device 420 comprises a dome shaped perforated metal plate 440. When using the burner, premix gas is fed through the perforations 447 of the dome shape perforated metal plate 440 of the inlet device into the mixing chamber. The burner 400 comprises an end cap 480, which closes off the mixing chamber at the side opposite to the side where the inlet device is provided. The exemplary burner 400 of FIG. 4 is provided so that in use of the burner, the premix gas flows from the inlet device through the cylindrical burner deck without further passing a gas diffusing device. Alternative burners however, can be provided with a diffuser into the mixing chamber. The burner 400 further comprises an ignition pen 490. The ignition pen 490 is provided at the side of the burner where the inlet device 420 is provided; and the ignition pen 490 has a length Lp (e.g. 30 mm, or e.g. 70 mm) along the axial direction of the burner 400. In the same way as the ignition pen, and/or in addition to it, a flame sensing pen can be provided.

[0040] Cylindrical burners have been made with internal diameter D 82 mm and length L 588 mm of the burner deck. The burner deck was a perforated metal plate, with a blind zone with length L1 at the base of the burner deck equal to 23 mm. No gas diffusing device was used in the mixing chamber of the burner. Burner A was a prior art burner with a flat perforated plate inlet disk. Burner B was a burner according to the invention with a dome shaped perforated plate inlet disk, with a largest distance P 22 mm from the surface of the dome shaped perforated inlet disk to the plane of the surface of the inlet disk for mounting the burner into a heating appliance. Ignition of each of the burners was tested 10 times at four different air over gas premix gas ratios. The four different air over gas premix gas ratios are indicated by the CO.sub.2 percentage in the combustion gas; respectively 8%, 8.5%, 9% and 9.5%. Table I indicates the number of successful ignitions (each time out of 10 trials). The test results show the improved ignition results of the burners according to the invention, especially when the burners are operating at low CO.sub.2 percentages of the combustion gas.

TABLE-US-00001 TABLE I Number of successful ignitions out of 10 ignition trials CO.sub.2 % Burner A Burner B 8 2 6 8.5 8 10 9 9 10 9.5 10 9