Non-centric oxy-fuel burner for glass melting systems

Abstract

A burner and method of combustion for a furnace or a forehearth includes a gas delivery member and a fuel delivery member having a portion thereof disposed at an interior of the gas delivery member and offset or angled from a longitudinal axis of the gas delivery member to provide gaseous oxidant and fuel flows for combustion.

Description

BACKGROUND OF THE INVENTION

The invention relates to burners for furnaces and furnace systems.

Conical concentric oxy-fuel burners have been used in the crown of glass melting furnaces to melt batch in the furnaces. Once a pre-positioned hole is drilled in the furnace crown and a burner block is installed in the hole, there is limited if no ability to change the direction of the turbulent flame being emitted from the burner. If a different direction is required for the flame, it is required to drill and install an alternate (different) burner hole in order to re-position the burner and hence the flame. Existing furnace designs, with their steelwork and crown expansion joints, frequently limit the location that burners can be installed in the furnace and as a result optimum flame coverage is not always achieved or blocks are angled excessively so that the burner flame is less effective. Concentric oxy-fuel burners produce conical flames perpendicular to the melt which in turn produce circular flame patterns at the melt. The resulting flame pattern produced by a plurality of spaced apart burners limits the total flame coverage at the surface of the melt. Concentric burners combust uniformly in the combustion space above the melt. This uniformity and intensity of combustion can provide excessive combustion in the free space between the crown and the melt resulting in less than optimum heat transfer and higher oxides of nitrogen (NOx) at the melt surface. The aforementioned limitations and disadvantages occur also with horizontal burners and burners used in forehearths of furnaces.

SUMMARY OF THE INVENTION

A burner such as an oxy-fuel burner is provided for a furnace or a forehearth, and which includes a gas delivery member, and a fuel delivery member having a portion disposed at an interior of the gas delivery member and offset from a longitudinal axis of the gas delivery member.

There is also provided a method for combusting product in a furnace or a forehearth, comprising providing a flow of gaseous oxidant along a first flow path to the furnace or the forehearth; providing a flow of gaseous fuel along a second flow path offset from the first flow path to the furnace or the forehearth; exposing the first flow path to the second flowpath; and combusting the gaseous oxidant and the gaseous fuel to provide a non-circular burn area.

There is also provided a burner, whereby one or more of the gas and fuel delivery members may be rotated along their respective longitudinal axes to control an angle of discharge of the burner flame and the resulting non-circular burn area.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, reference may be had to the following Figures, taken in conjunction with the detailed description, of which:

FIG. 1A discloses a partial cross-sectional plan view of a burner of the present invention for use with a furnace.

FIG. 1B discloses a cross-section of the burner taken along line 1B-1B of FIG. 1A.

FIG. 2A discloses a diagram of another embodiment of a burner of the present invention.

FIG. 2B discloses a cross-section diagram taken along line 2B-2B of FIG. 2A.

FIG. 3A discloses a diagram of another embodiment of a burner of the present invention.

FIG. 3B discloses a cross-section diagram taken along line 3B-3B of FIG. 3A.

FIG. 4 discloses a flame footprint provided by the burners of the present invention.

FIG. 5A discloses a diagram of another embodiment of a burner of the present invention.

FIG. 5B discloses a cross-section diagram taken along line 5B-5B of FIG. 5A.

FIG. 6A discloses a partial cross-section of another embodiment of the burner of the present invention for use with a furnace.

FIG. 6B discloses a cross-section of the burner taken along line 6B-6B of FIG. 6A.

FIG. 7A discloses a partial cross-section of still another embodiment of the burner of the present invention for use with a furnace.

FIG. 7B discloses a cross-section of the burner taken along line 7B-7B of FIG. 7A.

FIG. 8A discloses a partial cross-section of another embodiment of the burner of the present invention for use with a furnace.

FIG. 8B discloses a cross-section of the burner taken along line 8B-8B of FIG. 8A.

FIG. 9 discloses a cross section of a burner of the present invention mounted in a burner block of a furnace.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1A and 1B, there is shown a burner 10 of the present invention for use with a furnace, such as for example an oxy-fuel glass melting furnace or a forehearth of the furnace. Reference to use of the burner with a furnace also includes use of the burner with forehearth. The burner 10 consists of a gas pipe 12 or conduit, for delivering gaseous oxygen for example, having an exterior sidewall 14 constructed and arranged for disposition in a burner block of a furnace. The gas provided to and delivered in the gas pipe 12 is a gaseous oxidant such as for example gaseous oxygen at a purity level of 85%-100%; where less than 100% oxygen, the balance may be nitrogen and/or other noble gases, and combinations thereof. An internal space 16 of the gas pipe 12 is of sufficient size and shape to receive a fuel pipe 18 or conduit disposed therein. The fuel pipe 18 has an exterior side wall 20 and internal space 22.

The gas pipe 12, or oxidant pipe for example, is bent thereby providing an elbow 24 in the gas pipe 12. The pipe 12 is in fluid communication with a gas supply (not shown). A threaded exterior end 26 of the gas pipe 12 provides for releasable connection to the gas supply. An opposite or distal end 28 of the gas pipe 12 terminates in a burner block of the furnace (not shown) and is disposed at a select position above product melt in the furnace. Gaseous oxidant provided may be a single type of oxidant, such as for example oxygen, or selected from a composition of gases as well.

The interior 16 of the gas pipe 12 is sized and shaped to receive the fuel pipe 18 to be disposed therein, as shown in FIGS. 1A and 1b. The fuel pipe 18 is constructed of a material conducive to being exposed to the oxidant in the gas pipe 12. The fuel pipe 18 has an end or proximal end 30 extending from proximate the elbow 24 of the gas pipe 12, while an opposed or distal end 32 of the fuel pipe 18 terminates at approximately the same position as the end 28 of the gas pipe 12. The gas pipe 12 and fuel pipe 18 may terminate at the same location. The fuel pipe 18 is in fluid communication with a supply of gaseous fuel, such as for example natural gas, propane, liquid petroleum gas (LPG), synthetic gas (derived from organic solid, liquid and or gaseous sources, or combinations thereof), and combinations thereof. The fuel used may consist of a single gaseous fuel or a composition of fuels. The end 30 of the fuel pipe 18 projecting from the gas pipe 12 may also be threaded 31 for releasable connection to a source (not shown) of gaseous fuel.

Spacing or support members 34, 36, 38 are provided to support the fuel pipe 18 within the gas pipe 12 and provide the spaced relation therebetween without interrupting the flow of gas through the gas pipe 12. A weld or seal 40 is provided to seal the circumference of an inlet 42 in the gas pipe 12 through which the fuel pipe 18 is inserted.

Referring also to FIG. 1B, the disposition of the fuel pipe 18 at the interior 16 of the gas pipe 12 is more clearly shown. The gas pipe 12 and fuel pipe 18 are substantially parallel to each other from a point where the gas pipe 12 transits from the elbow 24 to a linear arrangement. It can be seen however that the disposition of the fuel pipe 18 within the gas pipe 12 is non-concentric; i.e., the gas pipe 12 and the fuel pipe 18 do not share a common longitudinal axis. Rather, a longitudinal axis 44 of the gas pipe 12 is offset with respect to a longitudinal axis 46 of the fuel pipe 18, as will be further discussed below, to provide a burner flame and flame footprint area for the particular furnace and product to be melted within the furnace. The burner can be adjusted to alter the flame footprint. This is accomplished because the gas pipe and fuel pipe are adapted, such as by construction and arrangement of their components, to be rotated about their respective longitudinal axes 44, 46.

The burner 10 of FIGS. 1A and 1B may also be constructed as an integral unit, thereby permitting rotation of the combined gas pipe and fuel pipe unit in the burner block to selectively control the disposition of the flame footprint area being emitted from the burner 10 into the furnace.

Other exemplary embodiments of a burner constructed in accordance with the present invention are illustrated in FIGS. 2A, 2B; 3A, 3B; 6A, 5B; 7A, 7B; and 8A, 8B, respectively. Elements illustrated in those Figures which correspond to the elements described above with respect to FIGS. 1A, 1B have been designated by corresponding reference numerals increased by one hundred, two hundred, three hundred, four hundred, etc., respectively.

FIGS. 2A and 2B show schematics of another embodiment of the burner 110 of FIGS. 1A, 1B. In FIGS. 2A and 2B, the fuel pipe 118 is disposed in the gas pipe 112 in an angled relationship, i.e. not parallel, such that the flame emitted from the burner into the furnace also provides a non-circular footprint at the melt in the furnace. The burner 110 may have the gas pipe 112 and fuel pipe 118 formed as an integral unit, whereby rotation of the unit as represented by arrow 60 can occur to provide the flame footprint at select positions on the melt within the furnace. Rotation of the burner unit can be done through 360°. FIG. 2A shows the gaseous oxidant flow, for example, and gaseous fuel flow to the furnace.

The fuel pipe 218 may also be angled sufficiently in the gas pipe 212 such that a distal end 232 of the fuel pipe contacts a distal end 228 of the gas pipe 212. Such an arrangement is shown in FIGS. 3A and 3B.

In FIG. 4 there is represented a plurality of flame footprints 62 that are provided by the burner 10 (110, 210, etc.) embodiments in the Figures. Each non-circular footprint 62 or burn area represents the footprint from its respective burner.

Referring to FIGS. 5A and 5B, the burner 310 is shown having the disposition of the fuel pipe 318 at the interior 316 of the gas pipe 312. The offset of the fuel pipe 318 with respect to the gas pipe 312 is shown in FIG. 5B.

In FIGS. 6A and 6B, the burner 410 is similar to the burner 110 diagram shown in FIGS. 2A and 2B. In particular, the fuel pipe 418 is introduced into the gas pipe 412 at an angle 48 such that the straight or linear portion of the gas pipe 412 and fuel pipe 418 are not parallel and are non-concentric. The offset of the fuel pipe 418 with respect to the gas pipe 412 is shown in FIG. 6B.

FIGS. 7A and 7B disclose a plurality of fuel pipes 518 disposed in a gas pipe 512. The plurality of fuel pipes 518 may be disposed as separate and discrete pipes or alternatively formed or arranged as a nested array or integral unit of fuel pipes, such as shown in FIG. 7B. The arrangement of the fuel pipes 518 in FIG. 7A are parallel with respect to each other and to the linear portion of the gas pipe 512 in which the fuel pipes 518 are disposed therein. As with other embodiments of the invention, the plurality of fuel pipes 518 and the gas pipe 512 can be formed as an integrated unit for being mounted in the burner block and subsequent rotation within the burner block to control the flame footprint area 562 at the melt in the furnace. The offset of the fuel pipes 518 with respect to the gas pipes 512 is shown in FIG. 7B. The array of fuel pipes 518 may share a common threaded portion 531 to releasably connect the fuel pipes 518 to a source of fuel.

In FIGS. 8A and 8B, there is shown a fuel pipe 631 disposed in concentrically arranged gas pipes. That is, a primary outer gas pipe 612 has an interior sized and shaped to receive a secondary inner gas pipe 50 therein. The inner gas pipe 50 has an interior 52 sized and shaped to receive the fuel pipe 618 therein. The inner gas pipe 50 has an inlet 54 in registration with the inlet 642 of the outer gas pipe 612 so that the fuel pipe 618 can be inserted into the inner gas pipe 50. In FIGS. 8A, 8B, the inner gas pipe 50 and fuel pipe 618 have a common longitudinal axis 646 along a back portion of each and are therefore concentric. The orientation of the fuel pipe 618 and the gas pipes 612, 50 is also shown in FIG. 8B. As with other embodiments of the present invention, the burner 610 of FIG. 8A may be formed as an integral unit for being mounted in the burner block of the furnace. The offset of the fuel pipe 618 with respect to the gas pipes 612, 50 is shown in FIG. 8B.

Referring to FIG. 9, there is shown a portion of a crown 56 of a furnace 57 in which a burner block 58 is mounted. The burner 10 of FIG. 1A is disposed within the burner block 58. It should be understood that other embodiments of the burner (110, 210, 310, 410, 510, 610) disclosed herein may be mounted in the burner block 58 as well. The burners 10, etc. are adapted to move in the direction of arrows 66, 68. With respect to the arrow 66, the burner 10 can be moved into a select position depending upon the amount of combustion that is desired to occur in the burner block 58. The distal ends of the fuel pipe 18 or pipes and gas pipe 12 or pipes terminate within the burner block 58 as shown, otherwise heat of the furnace atmosphere would melt the pipes if such were exposed from the burner block 58. Positioning the burner 10 in the burner block 58 effects combustion in the block 58, which in turn impacts the momentum and thrust of the flame provided by the burner 10. A higher momentum flame produces a smaller footprint 62 area, while a lower momentum flame produces a larger footprint 62 area. There is a lower oxidant concentration at area 70, as the gaseous fuel, for example, burns it uses up the oxidant and tends to seek area 72 where there is a higher concentration of oxidant to burn.

As shown in FIG. 9, a rich flame is provided from the burner at a distal end of the burner where the fuel pipe is closest to the sidewall of the gas pipe. An oxidized lean flame is provided from the distal end of the burner where the fuel pipe is further away from the side wall of gas pipe. The latter provides an increased or more expanded oxygen zone for combustion, thereby providing a relatively oblong shape, as opposed to a circular shape, in the burn area 62 or footprint of the flame impacting the melt of the furnace. See also FIG. 4

The non-circular footprints shown in FIG. 4 may also be provided by any one or combinations of the embodiments of the burners of the Figures.

The burners of the present invention may be used for glass melting, refining, and distribution. The discharge point of the fuel pipes are not concentric to the oxygen pipes, but staggered or off-set. This off-set and/or rotation of the burners enables the direction of the flame to be changed as well as the resulting flame footprint. The degree or amount of staggering or off-set will increase the amount of flame direction that can be achieved. The off-set can be further accentuated by angling the fuel conduit relative to the oxygen conduit. By way of example, the gas and fuel pipes have a circular cross-section, however the burner design may include gas and fuel pipes having different cross-sectional shapes, including but not limited to, elliptical, square, triangular, hex, etc. The fuel pipe can have a different cross-sectional shape than the gas pipe. Multiple or staged pipes can be utilized as well.

The arrows 66, 68 and are with respect to all burner 10, etc. embodiments of the invention as such can be rotated in the block 58. Such rotation can occur by the individual components of the gas pipes and fuel pipes, or by the integral units formed of a gas pipe or pipes and fuel pipe or pipes.

In the combustion process, the fuel reacts with the oxidant. By off-setting the pipes 12, 18, there is created a fuel-rich flame at the point where the pipes are closest, and a fuel-lean area at the point where the pipes are furthest apart. The fuel-rich portion of the flame will react with the oxidant at the fuel-lean side. This staging will also provide the benefit of lower oxides of nitrogen (NOx) and increase heat transfer. The staging lowers the amount of pre-combustion in the burner block 58 and reduces the momentum of the flame emerging from the burner block. Whilst the flame is turbulent the lower momentum flame will reduce the velocity on the batch surface and reduce volatilization of batch components including but not limited to boron and lead.

The lower momentum of the flame with respect to a furnace increases the residence time of the carbon in fuel and increases luminosity and heat transfer by radiation through sooting. The primary benefit of this invention is that the off-set of the gas and fuel pipes 12, 18, respectively, and hence the gas and fuel flows, delays the mixing of the gaseous fuel and gaseous oxidant until the flame hits the raw batch surface 64. The excess oxygen from the lean portion of the flame continues in its primary direction away from the remaining fuel components. The resulting flame footprint 62 or burn area is non-circular as shown in FIGS. 4 and 9. The non-circular flame burn area enables more energy to be directed into the melting area.

The lower momentum of the flame with respect to a forehearth or distributor for a furnace provides for the flame not to impact a surface of the melt, but rather to “curl” or alter direction to become substantially parallel to a surface of the melt.

It will be understood that the embodiments described herein are merely exemplary, and that a person skilled in the art may make many variations and modifications without departing from the spirit and scope of the invention. All such variations and modifications are intended to be included within the scope of the claims as described herein. It should be understood that embodiments described above are not only in the alternative, but may also be combined.

Claims

1. A burner for use in a furnace or a forehearth, comprising a gas delivery member, and a fuel delivery member having a portion disposed at an interior of the gas delivery member and offset from a longitudinal axis of the gas delivery member.

2. The burner according to claim 1, wherein a portion of the gas delivery member and the portion of the fuel delivery member are parallel with each other.

3. The burner according to claim 1, wherein the portion of the fuel delivery member is disposed at an angle at the interior of the gas delivery member.

4. The burner according to claim 1, wherein the gas delivery member and the fuel delivery member are formed as an integral unit.

5. The burner according to claim 1, wherein each of the gas delivery member and the fuel delivery member are adapted for rotational movement.

6. The burner according to claim 1, wherein the gas delivery member comprises a gas pipe.

7. The burner according to claim 1, wherein the gas delivery member comprises a first gas pipe with a first interior; and a second gas pipe with a second interior disposed in the first interior of the first gas pipe, the second interior sized and shaped to receive a portion of the fuel delivery member therein.

8. The burner according to claim 1, wherein the fuel delivery member comprises a fuel pipe.

9. The burner according to claim 1, wherein the fuel delivery member comprises a plurality of fuel pipes.

10. The burner according to claim 9, wherein the plurality of fuel pipes are an integral unit.

11. The burner according to claim 9, wherein the plurality of fuel pipes are disposed at an angle at the interior of the gas delivery member.

12. The burner according to claim 1, further comprising at least one support member disposed to support the gas delivery member in spaced relation with respect to the fuel delivery member.

13. A method for combusting product in a furnace or a forehearth, comprising providing a flow of gaseous oxidant along a first flow path to the furnace; providing a flow of gaseous fuel along a second flow path offset from the first flow path to the furnace; exposing the first flow path to the second flow path; and combusting the gaseous oxidant and the gaseous fuel to provide a non-circular burn area.

14. The method according to claim 13, wherein the first flow path and the second flow path are angled with respect to each other.

15. The method according to claim 13, further comprising providing another flow of gaseous oxidant along a third flow path to the furnace, the third flow path disposed within the first flow path and arranged to receive the second flow path therein.

16. The method according to claim 13, wherein the first flow path and the second flow path are alterable with respect to each other to control the disposition of the non-circular burn area.

17. The method according to claim 13, wherein the gaseous oxidant is selected from the group consisting of oxygen, oxygen and nitrogen, oxygen and other noble gases, and combinations thereof.

18. The method according to claim 13, wherein the gaseous fuel is selected from the group consisting of natural gas, propane, liquid petroleum gas, synthetic gas, and combinations thereof.

19. The method according to claim 18, wherein the synthetic gas is derived from a source selected from the group consisting of organic solid sources, organic liquid sources, organic gaseous sources, and combinations thereof.