EP0229048B1 - Gas burner - Google Patents

Gas burner Download PDF

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Publication number
EP0229048B1
EP0229048B1 EP85903118A EP85903118A EP0229048B1 EP 0229048 B1 EP0229048 B1 EP 0229048B1 EP 85903118 A EP85903118 A EP 85903118A EP 85903118 A EP85903118 A EP 85903118A EP 0229048 B1 EP0229048 B1 EP 0229048B1
Authority
EP
European Patent Office
Prior art keywords
burner
combustion chamber
flame
combustion
furnace
Prior art date
Legal status (The legal status 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 status listed.)
Expired - Lifetime
Application number
EP85903118A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0229048A1 (en
EP0229048A4 (en
Inventor
Victor Little, Jr.
Charles L. Thomas
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Asarco LLC
Original Assignee
Asarco LLC
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 Asarco LLC filed Critical Asarco LLC
Publication of EP0229048A1 publication Critical patent/EP0229048A1/en
Publication of EP0229048A4 publication Critical patent/EP0229048A4/en
Application granted granted Critical
Publication of EP0229048B1 publication Critical patent/EP0229048B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • F23D14/02—Premix gas burners, i.e. in which gaseous fuel is mixed with combustion air upstream of the combustion zone
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B7/00—Blast furnaces
    • C21B7/16—Tuyéres
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C3/00—Combustion apparatus characterised by the shape of the combustion chamber
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C5/00—Disposition of burners with respect to the combustion chamber or to one another; Mounting of burners in combustion apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23M—CASINGS, LININGS, WALLS OR DOORS SPECIALLY ADAPTED FOR COMBUSTION CHAMBERS, e.g. FIREBRIDGES; DEVICES FOR DEFLECTING AIR, FLAMES OR COMBUSTION PRODUCTS IN COMBUSTION CHAMBERS; SAFETY ARRANGEMENTS SPECIALLY ADAPTED FOR COMBUSTION APPARATUS; DETAILS OF COMBUSTION CHAMBERS, NOT OTHERWISE PROVIDED FOR
    • F23M2900/00—Special features of, or arrangements for combustion chambers
    • F23M2900/05021—Wall blocks adapted for burner openings

Definitions

  • This invention relates to high-velocity gas burners having enhanced flame stability. More particularly, the invention relates to high-velocity gas burners having enhanced flame stability over wide operating ranges and are utilizable in melting furnaces and the like.
  • Gas burners of the type provided by the present invention may be used in several different furnaces or units where a high heat level is required.
  • the present gas burners have been found to be effective in melting furnaces such as the upright melting furnace described and illustrated in U.S. Patents 3,199,977 and 3,366,465 issued to Albert J. Phillips et al.
  • the gas burners are inserted into each of the side wall ports and held in position therein by bolts which hold the mounting plating of each burner body tightly against the shell of the furnace so as to provide a substantially gas tight mounting.
  • the flame will burn both inside and outside of the combustion chamber and its shape in the chamber is defined by the shape of the chamber, with its shape outside the chamber being generally conical.
  • the burners typically have an igniter bar in the ignition section with the combustion chamber having a wider diameter than the outlet of the igniter section. The flame is held immediately downstream of the igniter bar and spreads to the unburned mixture passing by. Additional flame-holding is obtained with the annular area provided by the shoulder at the juncture of the igniter section and combustion chamber. Thus, two flame fronts are established, one spreading out from the igniter bar and the other spreading from the annular shoulder type flame-holder.
  • the flame spreading from the annular shoulder may be unstable in that it does not completely form on the shoulder and, consequently, forms a black or cold spot at that area on the shoulder.
  • This type flame produces an unstable flame which will waiver and flutter, as well as, in the case of a vertical furnace for melting copper, causes a cold spot at that area on the shoulder at which metallic copper may deposit.
  • This deposition of copper in the combustion chamber and/or unstable flame adversely affects the operation of the furnace causing impurities in the melted copper and possible shutdown of the furnace for cleaning.
  • Tho flnmn unstability is particularly severe at the start-up of the burner when the furnace and burner are cold, but is also undesirably present at "steady-state" operation.
  • furnaces of low capacity have tradiationally operated with but a single row of circumferentially spaced burners, since a second row has been thought would furnish more molten capacity than necessary, thus causing problems in turning the furnace melting rate down to lower rates without avoiding metal "slumping" and freezing within the furnace.
  • the problem of obtaining a uniform distribution of heat from a single row of burners has been a severe problem.
  • the metal easily can become suspended above the burner row, causing metal hand up problems when the nonmolten charge fails to descend from the large upper diameter section into the reduced lower diameter section of the furnace. Such a phenomenon results in high oxygen levels in the metal, uneven temperatures, and furnace "screaming".
  • It is an object of the invention to provide a high velocity gas burner which has enhanced flame stability over a wide operating range and in accordance with the invention there is provided a gas burner providing about a 2 1/2:1 turndown capacity while maintaining a stable flame with even and complete combustion over this range comprising a mixing section for uniting a stream of oxygen containing gas and a stream of fuel, a flame holder section having an exit diameter, D F for igniting the mixture of fuel and oxygen and an adjacent combustion chamber to retain the combustion and to enhance combustion, the combustion chamber being formed by a refractory burner tile and being of substantially cylindrical shape and having a diameter, D s , an effective length, L E , and an overall burner tile length, L T , characterized by the fact that the burner dimensions are correlated whereby D s /D F is between about 1.35 to 1.70 and L E /D s is between about 1.2 to 3.7.
  • the burner of the invention has increased burner tile life and minimal molten metal contamination caused by "cold" spots in the combustion chamber, among other benefits.
  • U.S. Patents disclose gas burners having a mixing section, a flame holder section and an adjacent combustion chamber. However none of these patents disclosed the critical D S /D F and L E /D S ratios necessary to obtain enhanced flame stability. Also in U.K. Patent 850907 and U.S patent 2,806,517 air and fuel are not mixed in a mixing chamber before the combustion chamber but rather in the combustion chamber.
  • the combustion chamber “effective length”, L E is the length of the tile lining as measured from the intersection of the combustion chamber with the flame holder section (the “shoulder") to the opposite end of the chamber.
  • the diameter, D s , of the combustion chamber is substantially constant throughout the chamber.
  • the chamber is comprised of an outer refractory tile housing having openings, preferably substantially circular, at each end for the entrance (D F ) and exit (D s ) of the combustion gases and is usually fabricated from a suitable high temperature resistant refractory substance, most preferably SiC.
  • the combustion chamber is further adapted to substantially combust the entering fuel and oxygen containing gases within, while continually maintaining a substantially even temperature gradient of predetermined temperature, preferably about (550°C) 2800°F., along the effective length of the chamber.
  • a substantially even temperature gradient of predetermined temperature preferably about (550°C) 2800°F., along the effective length of the chamber.
  • the ratio of the combustion chamber diameter, D s , to the diameter at the exit from the adjacent flame holder section, D F is between about 1.35to 1.70, most preferably, about 1.43; and
  • the ratio of the effective length L E , to diameter D s of the combustion chamber is between about 1.2 to about 3.70, and preferably about 1.56 or 3.00.
  • the burner assembly design will control the ratio of the overall length of the combustion chamber tile, L T , to the "effective length" L E of the chamber, i.e., the length of the chambertile lining as langesured from the intersection with the flame holder section to the end of the chamber exit to be between about 1.20 to about 2.00, and preferably about 1.47.
  • burners are described as having a mixing section 50, it will be understood by those skilled in the art that the fuel and air may be mixed outside of the burner and transferred through the igniting section or flame holder section 51 into the combustion chamber 52.
  • the present burners with this arrangement would function in the same manner, i.e., to provide a stable flame over a wide operating range.
  • These furnaces are designed to supply an effective distribution of heat to evenly melt the descending solid charge, i.e., preferably copper cathodes and scrap, without causing furnace clogging and metal freezing. Larger burners may suitably be employed for higher capacity furnaces.
  • burners providing flame stability over wide operating ranges are provided by this invention for energy levels up to 50x10 6 BTU/hr, or higher, preferably in the range of about 2 ⁇ 10 5 to about 20 X 10 6 e.g., 30x10 6 BTU/hr.
  • a preferred range is 0.7 to 10x10 6 BTU/hr, or 5x10 6 BTU/hr.
  • burner body 3 is comprised of a mixing section 50 for uniting a stream of fuel and a stream of an oxygen-containing gas (air) to form a unit stream and for introducing the unit stream into flame holder section 51.
  • the burner body is also provided with a combustion chamber section 52, which is more elaborately illustrated in Fig. 2, and is mounted on flange 53 against shoulder 54 of flame holder section 51.
  • Igniter bar 58 may be disposed in the throat, and a conventional electrically activated spark plug 59 for igniting the unit stream is mounted on the side of section 51 with the inner end of the spark plug disposed adjacent bar 58.
  • the combination of the throat and bar 58 are especially useful in maintaining combustion of the unit stream in combustion chamber 52, particularly at high fuel velocities.
  • Section 51 is also provided with openings 69 and 70 for taking samples of the unit stream.
  • Section 50 has an annular manifold portion 60, sleeve 61, bend or elbow portion 62, orifice plate 63 and observation port 64 provided with transparent eye piece 65.
  • Sleeve 61 which abuts shoulder 66 and the left end of section 50, cooperates with annular portion 60 to provide a manifold for introducing the smaller of the two streams to be united (usually the fuel stream) from pipe 36 through openings 67 into uniting chamber 68; the size and distribution of openings 67 about the periphery of the sleeve being selected to control entry to the fluid into the chamber.
  • the larger stream is introduced to chamber 68 from pipe 29 through the orifice in plate 63 and bend portion 62.
  • the larger stream of the two streams to be united is conducted to the burner body through an orifice into a bend leading to the uniting chamber, and the precise composition of the stream is determined in the manner disclosed in U.S. Patent 3,199,977.
  • Fig. 2 illustrates in detail the preferred structure of burner combustion chamber 52 when affixed in place in the refractory furnace wall 5.
  • the gaseous fuel and air unit stream passes through flame holder section 51 past igniter bar 58, whereupon the mixture is ignited by spark plug 59 or another effective firing means, and enters burner combustion chamber 52.
  • Combustion chamber 52 is preferably substantially completely cylindrical in dimension, extending from the "shoulder" 99 created by the intersection of the combustion chamber 52 and adjacent flame holder section 51, and the chamber extends to the beginning of exit funnel 96, a distance 94 in dimension, at which point the combusted fuel gases enter the furnace and melts the metal charge.
  • a removable SiC sleeve in the broadest embodiment of the invention, similar results can probably be provided if the entire burner tile structure and sleeve were one-piece cast, or the like, so long as the structure conforms to the ratios and dimensions hereinafter described.
  • the use of a sleeve allows ease of replacement of eroded or worn sections, together with permitting changes in combustion chamber dimension should the occasion arise for operating at different tonnage levels.
  • predetermined dimension of the sleeve is meant the particular substantially uniform thickness of the sleeve wall.
  • the sleeve is axially centered within the chamber bore diameter 92, and is bonded, preferably oxide bonded, to the adjoining refractory tile 49.
  • burner performance over a range of operating conditions is attained when burner tile 49 containing sleeve 90 has been dimensioned in a manner so as to conform to several important chamber parameters; viz., (1) the ratio of the diameter 95 of the combustion chamber (D s ) to the diameter 97 of the flame holder exit (D F ); and (2) the ratio of the "effective length" (L e ) to the sleeve diameter (O s ).
  • the burner is designed to conform to the ratio of the overall tile length (L T ), 100, as the length measured along the chamber centerline from the entrance to the tile to an intersecting point of a plane at the exit face of the combustion chamber tile 49, to the "effective length" (L E ) 94 of the combustion chamber, i.e., the length of the tile lining as measured from the intersection with the flame holder section (shoulder 99) to the end of the sleeve lining at the chamber exit.
  • L T overall tile length
  • L E effective length
  • This structural relaitionship of D s /D F serves to control the degree of expansion of the fuel mixture as it exits the flame holder section and enters into the combustion chamber. This controlled expansion allows ignition to occur and the flame to seat on the shoulder formed by the flame holder section and the combustion chamber section.
  • combustion reactions frequently did not proceed until about halfway into the chamber, a condition believed created by a sudden large expansion of the high speed fuel flow upon entrance into the combustion chamber. It has, surprisingly, been determined that a properly dimensioned combustion chamber visa-vis the igniter section (D s /D F ) can provide and maintain a "stable" flame whereby the melting capacity of the burner is maintained at an optimum level, creating a flame which melts metal primarily through a convection mechanism.
  • the maintaining of a stable flame is particularly desirable since a long, unstable fvame is particularly desirable since a long, unstable flame is characteristic of a relatively low degree of combustion of the fuel and oxygen.
  • a flame permits a greater amount of copper build up within the chamber and an increase in the oxygen content of the copper to undesirable levels.
  • a short stable flame in contrast, is indicated of substantially complete combustion occurring within the chamber.
  • a further consequence of incomplete combustion is the substantial variation in refractory tile temperatures and uneven refractory wear causing a shorter refractory tile life.
  • a preferred range of combustion chamber/flame holder exit diameter ratios is about 1.35 to 1.70, and, more preferably, about 1.40-1.45, e.g. 1.43.
  • the ratio of the effective length L E of the combustion chamber to the sleeve diameter D s of the chamber has also been found to be an important performance parameter for the burner. This is believed due to the fact that this ratio provides a suitable geometry of the combustion chamber which enhances combustion and maintains heated walls throughout this length. This ratio has been found to be dependent on the operating energy range (BTU/hr.) of the burner with, in general, increasing operating energy ranges requiring lower ratios.
  • a range of about 1.2 to 3.7 may suitably be employed within the invention with best results being obtained when the ratio (L E /D s ) ranges from about 1.85 to 3.70, and, most preferably about 2.5-3.5, e.g, 3.0, for smaller sized burners less than about 10 ⁇ 10 6 BTU/hr., e.g., about 0.5x 10 6 to 4x 10 6 BTU/hr.
  • the ratio ranges from about 1.2 to 1.7, e.g., about 1.3 to 1.6.
  • the ratio of the overall tile length (L T ) of the combustion chamber tile of the "effective length" L E , (L T /L E ) is essentially a determination of what length sleeve provides the desired result for a particular burner. Best results have been obtained when the aforementioned ratio varies from about 1.20 to 2.00, with a preferred configuration for a refractory tile about 11 inches long having a SiC sleeve extending about 6-9 inches, most preferably, about 7 1/2 inches, giving a ratio of 1.47.
  • Another important system parameter is the velocity at which the combustion gases pass through the chamber. Surprisingly, the velocity of the exiting gases is about two times greater, for best results, than gas velocities occurring in burners of the prior art. This is believed due to results obtained from correlating the burner dimensions in accordance with the above ratios and the increased combustion of the fuel gases.
  • Figures 3 and 4 described an assembly comprised of a vertical shaft melting furnace 1, launder 2, and associated piping for supplying a plurality of burners 3 positioned in two circumferential rows with fuel and an oxygen-containing gas (air).
  • furnace 1 is provided in its side walls and bottom with a refractory lining 5 which is surrounded by shell 6, fabricated from an appropriate metal, preferably a steel which has been suitably assembled as by welding to provide a shell which is substantially gas tight.
  • the furnace side walls are provided with a plurality of ports 7 for combustion burners 3.
  • the lower side walls 8 of the furnace are sloped inwardly, and the furnace bottom 9 is sloped towards tap hole 10, which leads into launder 2.
  • air from blower 11 is passed at a desired positive pressure through pipe 12 to a control valve 13 feeding the air to manifolds 14, from where it is delivered at a desired positive pressure to the individual burners 3 by lagged pipes.
  • the gaseous fuel supplied from a suitable source, flows at a desired positive pressure through pipe 15, provided with heater 16 that is supplied with heat in any suitable manner, as for example, with a heat exchanger using either electrical heat or hot products of combustion, for preheating the fuel.
  • the preheated fuel is subsequently passed through the lagged pipes and control valves 16 A to the individual burners 3, which may also be lagged to prevent heat loss.
  • Burners 3 are inserted into each of the side wall ports and held in position therein by bolts 17 which hold the mounting plate 18 of each burner tightly against shell 6 so as to provide a substantially gas tight mounting.
  • Such a mounting together with the closed construction of the burners, substantially prevents introduction of extraneous air into the furnace through the burner ports.
  • a plurality of burners are positioned in the furnace wall with each burnsr preferably in a predetermined spaced relationship to the other burners about the furnace.
  • a preferred high velocity burner design is shown in Figure 2 and has the following dimensions.
  • the combustion tiles 49 for the burners are square and 9 inches on its side.
  • Sleeve diameter D s of the combustion tile 49 of the burners is about 2 1/2 inches in diameter
  • the exit diameter of flame holding section 51, D F is about 1.75 inches
  • D s /D F is about 1.43.
  • the burner is provided with an electrically actuated spark plug 59 to ignite the unit stream and is provided with an igniter bar 58 to assist in maintaining combustion of the unit stream in the combustion chamber 52.
  • the effective length L E measured from the end of the flame holding section 51 to the end of the combustion tile 49 is about 7 1/2 inches.
  • the ratio of the effective length, L E to the exit sleeve diameter D s , L E / D s 3.00.
  • This burner provides a stable flame over a turn-down ratio of about 2.5:1 in a vertical melting furnace of the type described in U.S. Patent No. 3,199,997 having a design melting capacity of about 20 STPH.
  • a high capacity burner providing in excess of 10x10 6 BTU/hr. according to the invention has a sleeve diameter D s of about 10 1/4 inches, an exit diameter D F of about 7 1/2 inches, an effective length L E of about 16 inches and a tile length L T of about 23 3/16 inches.
  • the ratio of D s /D F is 1.37, L E /D s is 1.56 and L T /L E is 1.45.
  • This burner provides a stable flame over a turn- down ratio of about 2.5:1.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Glass Compositions (AREA)
  • Vertical, Hearth, Or Arc Furnaces (AREA)
  • Gas Separation By Absorption (AREA)
  • Pre-Mixing And Non-Premixing Gas Burner (AREA)
  • Gas Burners (AREA)
  • Treating Waste Gases (AREA)
  • Furnace Details (AREA)
EP85903118A 1985-06-03 1985-06-03 Gas burner Expired - Lifetime EP0229048B1 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US1985/001039 WO1986007436A1 (en) 1985-06-03 1985-06-03 Gas burner

Publications (3)

Publication Number Publication Date
EP0229048A1 EP0229048A1 (en) 1987-07-22
EP0229048A4 EP0229048A4 (en) 1989-01-24
EP0229048B1 true EP0229048B1 (en) 1990-11-07

Family

ID=22188709

Family Applications (1)

Application Number Title Priority Date Filing Date
EP85903118A Expired - Lifetime EP0229048B1 (en) 1985-06-03 1985-06-03 Gas burner

Country Status (11)

Country Link
EP (1) EP0229048B1 (no)
JP (1) JPS62503115A (no)
KR (1) KR930007447B1 (no)
AT (1) ATE58221T1 (no)
AU (1) AU573863B2 (no)
BG (1) BG47799A3 (no)
BR (1) BR8507221A (no)
DE (1) DE3580486D1 (no)
FI (1) FI86470C (no)
NO (1) NO870410L (no)
WO (1) WO1986007436A1 (no)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5199866A (en) * 1992-03-30 1993-04-06 Air Products And Chemicals, Inc. Adjustable momentum self-cooled oxy/fuel burner for heating in high temperature environments
US5256058A (en) * 1992-03-30 1993-10-26 Combustion Tec, Inc. Method and apparatus for oxy-fuel heating with lowered NOx in high temperature corrosive environments
US5547368A (en) * 1993-03-01 1996-08-20 Air Products And Chemicals, Inc. Process and device for combustion-enhanced atomization and vaporization of liquid fuels

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2806517A (en) * 1950-11-16 1957-09-17 Shell Dev Oil atomizing double vortex burner
US2839128A (en) * 1953-03-25 1958-06-17 Thermal Res And Engineering Co Burner
GB850907A (en) * 1959-03-05 1960-10-12 Tulifa Verken Ab An improved burner tube for oil burner units
BE633958A (no) * 1962-06-22
US3299940A (en) * 1963-06-22 1967-01-24 American Smelting Refining Burner structure
US4120639A (en) * 1977-06-30 1978-10-17 Midland-Ross Corporation High momentum burners
JPS5414028A (en) * 1977-07-01 1979-02-01 Chugai Ro Kogyo Kaisha Ltd Low nox burner
JPS5752496A (en) * 1980-09-17 1982-03-27 Tokyo Shibaura Electric Co Washing machine
JPS5826489A (ja) * 1981-08-11 1983-02-16 松下電器産業株式会社 高周波加熱装置

Also Published As

Publication number Publication date
AU573863B2 (en) 1988-06-23
FI870443A (fi) 1987-02-02
AU4496385A (en) 1987-01-07
FI86470C (fi) 1992-08-25
EP0229048A1 (en) 1987-07-22
DE3580486D1 (de) 1990-12-13
KR880700213A (ko) 1988-02-20
BR8507221A (pt) 1987-08-04
FI870443A0 (fi) 1987-02-02
EP0229048A4 (en) 1989-01-24
WO1986007436A1 (en) 1986-12-18
NO870410L (no) 1987-02-02
BG47799A3 (en) 1990-09-14
ATE58221T1 (de) 1990-11-15
FI86470B (fi) 1992-05-15
KR930007447B1 (ko) 1993-08-11
JPS62503115A (ja) 1987-12-10

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