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
• • 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
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23Q—IGNITION; EXTINGUISHING-DEVICES
  • F23Q2/00—Lighters containing fuel, e.g. for cigarettes
  • F23Q2/16—Lighters with gaseous fuel, e.g. the gas being stored in liquid phase
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
  • B22F3/002—Manufacture of articles essentially made from metallic fibres
• • 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
  • F23D14/02—Premix gas burners, i.e. in which gaseous fuel is mixed with combustion air upstream of the combustion zone
• • 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
  • 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
  • F23D2203/00—Gaseous fuel burners
  • F23D2203/10—Flame diffusing means
  • F23D2203/102—Flame diffusing means using perforated plates
  • F23D2203/1023—Flame diffusing means using perforated plates with specific free passage areas
• • 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
  • F23D2203/00—Gaseous fuel burners
  • F23D2203/10—Flame diffusing means
  • F23D2203/105—Porous plates
  • F23D2203/1055—Porous plates with a specific void range
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23D—BURNERS
  • F23D2212/00—Burner material specifications
  • F23D2212/20—Burner material specifications metallic
  • F23D2212/201—Fibres
• • 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
• • 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
  • F23D2900/14—Special features of gas burners
  • F23D2900/14001—Sealing or support of burner plate borders

Definitions

• the invention relates to a porous metal fiber plate.
• Such plates in which the fibers are sintered to one another, are used, amon other things, as filter media.
• this goal is achieved by providing a porous metal fiber plate i which a regular pattern of transverse holes or passages has be made which, all together, occupy an overall free passage area 5 % to 35 % of the total surface area of the plate, while ea hole has a surface area of between 0.03 and 10 mm 2 .
• a porous metal fiber plate i which a regular pattern of transverse holes or passages has be made which, all together, occupy an overall free passage area 5 % to 35 % of the total surface area of the plate, while ea hole has a surface area of between 0.03 and 10 mm 2 .
• the equivalent fiber diameters may range between about 8 ⁇ m and 150 ⁇ m. With an equivalent fiber diameter is meant here the diameter of a fictive perfectly cylindrical fiber, the cross-section surface of which corresponds to the average cross- section surface of a real fiber which is not perfectly circular or even not circular at all.
• the thickness of the plate is preferably between 0.8 mm and 4 mm and the plate is sufficiently rigid and strong to resist the selected pressure drops at the desired poro ⁇ sities. Plate thicknesses of 1, 2 and 3 mm, for example, are sui ⁇ table. The porous plate therefore does not need any extra support near its bottom surface or its top surface (e.g. with a steel plate). Thus the bottom and top surfaces remain freely accessible.
• It is another object of the invention to provide a gas burner device comprising a housing with supply means for the gas to be burned, a distribution element for the gas stream and a porous metal fiber plate as a burner membrane which enables a control- Table and uniform gas flow to the burner membrane exit surface and as a consequence a uniform burning process over the entire burner surface and with a low pressure drop in the gas flow crossing the membrane.
• Yet a further object of the invention resides in the provision of a durable burner membrane wherein certain surface areas do not prematurely deteriorate due to overloading or overheating versus other areas, due to inhomogeneities in porosity thereby causing uncontrollable preferential gas glow paths and burning areas.
• Another important object of the invention relates to the design of a porous metal fiber plate, usable as a burner membrane over an enormously broad power range and which is therefor suitable f both surface radiant and blue flame modes.
• a further object of the invention deals with the design of burn membrane plates which offer remarkably low CO and NO x -emissions a high yields.
• Yet another object of the invention concerns the design of a g burner with less constraints as to prefiltration of the inflowi gas stream.
• Figure 1 is a sketch of a porous plate with circular hol according to the invention.
• Figure 2 shows one possible way of assembling this plate in housing with supply means for the gas and transport tion and flow means for it through the plate.
• Figure 3 represents schematically a pipe-shaped device f passing the gas flow through.
• Figures 4 to 7 relate to top views of several alternative patterns of transverse passages to be arranged in t porous plates.
• Figure 8 shows a cross-section of a gas burner device accordin to the invention in which an acoustic muffling layer i clamped between the burner membrane and the distributio element.
• Figure 9 presents a cross-section of a gas burner device in whic a number of muffling layers are included, possibly alon with empty interspaces.
• the porous metal fiber plate 1 comprise holes 2 spaced at regular distances p (pitch) from one another These holes are by preference cylindrical in shape and, in parti cular, circul r-cylindrical.
• the area of each hol 2 is the same and lies between 0.03 and 3 mm 2 , though more prefe rably between 0.4 and 1.5 mm 2 , respectively between 0.5 an 0.8 mm 2 .
• these dimensions are to be chose i.a. depending on the thickness of the plate 1, its porosity an the intended application.
• the diameter of each circle will be 0.8 mm for surface area of approximately 0.5 mm 2 .
• the holes 2 are by prefe rence made with a punching operation since this assures a smoot cylinder wall. If so desired, holes can also be punched wit triangular, square, rectangular or other shapes. The holes ma also be made with laser beams. Thus, in principle, very smal holes with a diameter of at least 0.2 mm are possible for thi plates.
• Figures 4 to 7 illustrate other preferred shapes of passages slots of different shapes and their regular distribution over th plate surface.
• Two examples of a suitable regular pattern o adjacent rectangular slots 9 are shown in figure 4 (right side resp. left side).
• Circular passages .2 and rectangular slots 9 ca alternate over the surface as shown in figure 5.
• ova or elliptic slots 11 can alternate with circular holes 2 a represented in figure 7.
• a pattern of cruciform slots 10 possible also as illustrated in figure 6.
• a great number regular distributions of passages with different shapes conceivable in view i.a. of minimizing or avoiding any whistli effect in the gas flow as will be explained further.
• Each of the slots 9, 10, 11 should preferably have a surface ar of between 1 and 10 mm 2 .
• Rectangular, or substantially rectangul slots will have a slot width "w" of between 0,3 mm and 2 mm and length "1" of between 3 mm and 20 mm.
• the relatio 0,5 mm ⁇ w ⁇ 1 mm and 5 mm ⁇ 1 ⁇ 10 mm will apply.
• plate with rectangular slots 9 according to e.g. figure 4 or the overall free passage area occupies 20 % to 30 % of the tot surface area of the plate.
• the pitch p between adjacent holes 2 is chosen such that the total surface area comprises 5 % to 25 % of the total surface ar of the plate, and preferably 8 % to 16 %. Values of 10 %, 12 % a 15 % are adequate.
• the successive holes are by preference ordered in a patte of adjacent, equilateral triangles in which each hole 2 occupi a corner of the triangle.
• the porosity of the plate (between the holes 2) is always betwe 60 % and 95 %, but preferably between 78 % and 88 %.
• the pla surfaces can be flat, can have a relief (be embossed), or else c be curved or corrugated, for example.
• stainless steel fibers are suitable.
• steel fibers contai ning Cr and Al are to be used, preferably those containing also small amount of yttrium.
• the porous plate 1 according to th invention can be assembled in a standard manner in a housing with supply means 4 for the gas.
• a flammable gas mixture e.g. natural gas/air
• the device thus formed can, moreover, comprise a distribution element 5 for the incoming gas flow.
• this will be a plate with suitable holes o passages arranged in it such that a uniform flow of gas with suitable pressure reaches the inlet side of the porous plate 1.
• the surface area of the free passages in the distribution plate can amount to between 2 % and 10 %.
• the distribution plate 5 also serves as support element for the end plate 8.
• the distribution element can possibly be corrugated and can also function to neutraliz possible sound resonances in the gas flow or as a flame arreste or barrier should they backfire into the gas inlet side of th plate 1, e.g. as a result of damage (cracks) in the burner plate
• the holes 2 can have a conical entrance 6 and cylindrical exit 7 or vice versa (plate upside down) : a cylin drical entrance and a conical exit.
• a distribution element 5 is by preference also provided for th gas supply, along with an end plate 8 in the cylindrical devic according to figure 3. Due to the flexibility of the membran plate 1 with hole pattern 2, cylinders of relatively small dia meters can be bent from flat plates.
• the tongues of flame therefore can dance up and do above the burner surface or even oscillate with their flame bas between a position in (or even under) the holes and a positi above the holes (above the burning surface). This can be acc
• the solution according to the invention consists of providin gas burner device which includes a housing comprising following elements, positioned in succession downstream one after the other: means of supply for the gas which is to be burned, a distribution element, at least one acoustic muffling layer through which gas can pass, and a porous plate as burner membrane provided with a regular pattern of holes that, taken together, make up 5 % to 35 % of the surface area of the plate, with each hole having a surface area of between 0.03 mm 2 and 10 mm 2 .
• the gas burner device includes a housing 16 with the following elements positioned in succession downstream from one another : a supply duct 15 for the gas mixture and a distribution element 5 in the form of a perforated metal plate which lies against the bent edge 22 of said supply duct 15.
• the housing 16 is attached to the supply duct with a weld 17.
• the distribution plate 5 is, for example, 0.4 mm thick and provided with holes 18, each having a diameter of 0.4 mm.
• the holes or passages 18 can be placed in the corner points of a pattern of adjacent equilateral triangles with a triangle side (i.e. pitch between the holes) of 1.25 mm. This means a free passage surface area of the plate 5 of approximately 10 %. Depending on the circumstances, this free surface area could just as well lie between 5 % and 20 %. Below 5 %, the pressure drop becomes too high at high gas flow rates; above 20 % the distribution effec for the gas mixture becomes insufficient at low flow rates.
• a permeability can be chosen of between 30 mes and 60 mesh.
• Two or more meshes 13 can also be stacked on top one another, preferably of different permeabilities.
• porous membra plate 1 Downstream from the welded wire mesh (or meshes) 13, whi operates as an acoustic muffling layer, is the porous membra plate 1, which is provided with a regular pattern of holes 1
• This porous plate is again preferably a sintered metal fiber pla in which the fibers are heat-resistant, i.e. resistant against t high burner temperatures occurring during operation and resista against thermal shocks.
• the fibers therefore, are preferab steel fibers with a suitable Cr and Al content: e.g. FeCrAll fibers as described hereinbefore.
• Plate 1 for example, is 2 mm thick and has a porosity of 80.5 between the holes.
• Plate 1 is clamped against the housing 1 with a ceramic mat 14 inserted between the two.
• the device can, for example, include one muffling lay 13 that is in surface contact with the distribution element 5.
• the layer 13 can be in surface contact wi both element 5 and porous plate 1.
• the muffling layer 13 is built up as a laminate made up of two wire meshes 25 and 26 with a porous mass interposed between them. If so desired, the porosity, and there ⁇ fore also the pressure drop over this laminate, can be changed under the influence of the gas pressure of the incoming mixture or via external operating means (not shown).
• the porous mass 27 can, for example, be a resilient mass of fibers, e.g. steel wool. Besides a more intense distributive effect on the mixture, this transverse compression respectively relaxation of the laminate can decrease the pressure drop over the membrane 1 at high flow rates so that again the danger of resonance becomes less critical.
• the muffling layer 13 can consist wholly or partially of a porous mass of fibers 27. If so desired, this mass can fill up the whole interspace between plate 1 and element 5.
• mineral fibers are to be utilized (e.g. rockwool or steel wool) .
• the porous plate 1 can also include a 'laminate of wire meshes sintered to one another. Woven or knitted wire meshes of heat-resistant wires can be used for this purpose.
• a suitable laminate structure is described in U.S. patent 3.780.872. On the whole . these laminates will be more rigid than those made of sintered fiber webs. Therefore they are mounted by preference in flat burners. A pattern of holes is of course also punched through these laminates as described above.
• sintered porous plates 1 as such - made of shavings or cut fibers, or else of wire meshes such as • described above - can also be utilized.
• a muffling layer 2 is not required and embodiments according to or analogous to those described in the Belgian patent application 09200209 a then applicable.
• ceramic fibers wires can also be used.
• a flat sintered porous metal fiber plate 1 produced according the invention and possessing the characteristics given below c be used as a membrane for a gas burner device.
• the characteristi and advantages of this concept with respect to previously prese ted burner membranes are explained below.
• the steel fibers to be used are resistant against high temper tures and, for this purpose, contain by percent weight, f example, 15 to 22 % Cr, 4 to 5.2 % Al , 0.05 to 0.4 % Y, 0.2 0.4 % Si and at most 0.03 % C. They have a diameter of between and 35 ⁇ m - for example, approximately 22 ⁇ m.
• the fibers can obtained by a technique of bundled drawing, as known, for exampl from U.S. patent 3.379.000 and as is mentioned in U.S. pate 4.094.673. They are processed into a non-woven fiber web accordi to a method described in or similar to the method which is kno from U.S. patents 3.469.297 or 3.127.668. Afterwards, these w are consolidated by pressing and sintering into a porous plat with a porosity of between 78 % and 88 %. Porosities of 80.5 83 % and 85.5 % are very common.
• porous plate 1 it is also possible to use thicker metal fibers as heat-resist fibers in the porous plate, e.g. fibers with equivalent diamet of between 35 and 150 ⁇ m and consisting of wire shavings cuttings from a plate of the desired heat-resistant alloy (e. FeCrAlloy). These fibers look rather like steel wool and can manufactured according to a shaving. process as disclosed e.g. U.S. patent 4.930.199.
• This porous plate 1 is now placed in a mould and, with a suitable punching device (stamp with punching pins), it is provided with a regular pattern of perfectly delimited circular cylindrical passages or holes 2 having a diameter of, for example, 0.8 mm.
• the gas mixture to be burned is passed through the porous membrane plate 1.
• the gas mixture now flows mainly through the holes 2, because of which the pressure drop over the membrane 1 is noticeably lower (than for plates without holes) for a particular flow rate or by which higher flow rates - and conse ⁇ quently larger thermal outputs or powers - can be achieved for a particular pressure drop value.
• the power range can now be selec ⁇ ted between 150 and 900 kW/m 2 for a radiant surface combustion an can be increased to that of a blue flame surface burner with a output or power of up to 4000 kW/m 2 , depending on factors such a the excess air in the gas mixture in relation to a stoichiometr gas combustion mixture.
• the porosity of the plate 1 results in the fact that a sma portion of the gas always penetrates through the pores between t holes 2 to the hot exit surface. As explained below, this great promotes a uniform and stable burning over a broad load or pow range. Especially at higher flow rates, the portion of gas th passes between the holes through the plate increases proportiona ly. It is now precisely at these higher flow rates (and cons quently higher powers if the percent of excess air remains t same in the gas mixture) that the tendency to blow away the bl flame at the level of the holes needs to be counteracted.
• T burning of the gas at the surface of the plate between the hol 2 maintains, as it were, a stable (blue) flame front over t whole plate surface and prevents this front (or the blue fla tongues within it) from being blown away from the plate surfac
• the tongue-shaped flames above each hole remain, as it were, wi their base - or root - anchored to the plate surface.
• the largely horizontal orientation of the fibers within the poro plate also promotes the isolating effect of the membrane. Indee the heat conduction runs primarily in the outside surface (radia side) of the plate and much less in the depth (throughout t thickness) of the plate. Moreover, there is the ongoing unifo cooling effect of the cold gas supply in direct contact with t layer of fibers on the gas inlet side. In turn, this uniform he distribution at the level of the plate surface promotes the un form combustion of the gas layer and a stable burning state ov a broad load or power range at the exit side of the plate betw the consecutive holes 2.
• a porous membrane layer 1 that its gas inlet side is attached, for example, to a supporting st plate and in which the porous layer together with the supp plate have the same pattern of holes, this isolating effect will on the whole be smaller and the powers that can be attained will be lower.
• a porous membrane without holes that is attached to a gas distribu- tion plate support with a regular pattern of many small holes (e.g. hole diameters of 0.3 mm and a pitch or center-to-center distance of adjacent holes of 1.25 mm) the attainable gas flow rate for a given pressure drop will remain more limited than with the plate according to the invention. Further with this arrange- ment, the high powers per unit of burner surface area are not attainable.
• the plate thickness, its porosity and the size of the passages or holes must of course all be coordinated with one another so that for any burner state no backfiring towards the gas inlet side will occur.
• a radiant surface burner state was noted up to something li 800 kW/m 2 . At higher powers, the burning changed into a blue fl mode.
• the porous plate 1 is in surfac contact with the 48 mesh wire mesh 13.
• a gas mixture of natural gas and air was passed through the compact combination in housin 16 of this wire mesh 13 clamped together between the 2 mm thic porous plate 1 and the distribution element 5 with free passag surface area of 10% (both described above).
• the square burne surface measured 150 mm x 150 mm.
• Various proportions of exces air were utilized (1.1 to 1.3) and the flow rates were increase such that powers were developed ranging from 500 kW/m 2 to 500 kW/m 2 .

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• General Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Gas Burners (AREA)
• Laminated Bodies (AREA)
• Panels For Use In Building Construction (AREA)

Applications Claiming Priority (5)

Publications (2)

Family

ID=25662619

Family Applications (1)

Country Status (8)

Cited By (10)

Families Citing this family (67)

Family Cites Families (4)

• 1993
  • 1993-02-26 AT AT93903734T patent/ATE174681T1/de not_active IP Right Cessation
  • 1993-02-26 JP JP51519093A patent/JP3463934B2/ja not_active Expired - Fee Related
  • 1993-02-26 BR BR9306001A patent/BR9306001A/pt unknown
  • 1993-02-26 EP EP93903734A patent/EP0628146B1/de not_active Expired - Lifetime
  • 1993-02-26 WO PCT/BE1993/000010 patent/WO1993018342A1/en not_active Ceased
  • 1993-02-26 DE DE69322622T patent/DE69322622T2/de not_active Expired - Fee Related
  • 1993-02-26 CA CA002117605A patent/CA2117605A1/en not_active Abandoned
• 1994
  • 1994-08-30 KR KR1019940703041A patent/KR950700517A/ko not_active Withdrawn

Non-Patent Citations (1)

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