Patent Application
20070248923
1. Field of the Invention
The present invention relates to a direct flame impingement burner for heating metallic materials such as blanks, slabs, and the like.
2. Description of the Related Art
Direct flame impingement burners are used for heating various metallic materials. Instead of heating a volume of the atmosphere in, for example, a furnace, and thus heating a material indirectly, the flame impinges directly upon the surface of the material, thus heating it directly. That gives rise to better heat transfer efficiency from the burner to the material.
Such burners are commonly used in, for example, industrial furnaces for the continuous or discreet heating processing of metallic materials. They can also be used separately, for example when preheating or melting materials.
A typical direct flame impingement burner includes a nozzle, in turn including at least one fuel opening and one oxidant opening, from which fuel and oxidant are dispatched, respectively.
Such a typical direct flame impingement burner is fed with a gaseous fuel, for example natural gas, and a gaseous oxidant, for example oxygen, for the fuel and the oxidant, respectively. The burner includes fuel and oxidant nozzles that can be arranged at a distance from each other, in order to gain control over parameters such as combustion temperature, NOx content of combustion products, and the like.
However, in order to optimize the burner behavior arid efficiency in various applications, the respective nozzle openings for fuel and oxidant in the burner head can be arranged in a variety of ways. The choice of arrangement will, among other things, affect the chemical reaction surface between the fuel and oxidant.
Naturally, each nozzle opening needs to be supplied either with fuel or with oxidant. Thus, in an arrangement with several individual openings for both fuel and oxidant, there is a need for multiple supply piping. This is especially true in the common case in which control over the gas pressure in each individual opening is desired for control over the combustion characteristics. In order to fit the supply pipes, valves, and the like, the burner will have to be made quite bulky, something that constitutes a problem in terms of placement in a production line or in an industrial furnace. Also, the cost of production as well as the cost of maintenance of the burner both increase because of the many individual parts.
When heating metallic materials, it is often desired to heat the material uniformly across a larger part of the surface area of the material. For example, when continuously processing metal sheets, it is often desired to obtain a uniform heating profile across the whole width of the processed metal sheet, in order to avoid temperature gradients, and the like. When using direct flame impingement burners, there is therefore a need to use several direct flame impingement burners in conjunction, arranged side by side.
In the case when using several direct flame impingement burners, there is a problem in obtaining a uniform heating profile across all the individual direct flame impingement burners. Namely, in order to obtain such a uniform heating profile, all individual burners need to provide the same heating power to the material. Since the heating power of the direct flame impingement burner depends on the gas pressure of the fuel and the oxidant at each respective opening, those pressures need to be equal in corresponding nozzle openings over the whole range of individual direct flame impingement burners.
When using tubing or piping in order to supply each individual fuel or oxidant nozzle opening, besides the problem of bulkiness, it is difficult to obtain the desired equal gas pressures because of pressure drops that occur in the various parts of the tubing or piping, such as in individual tubes, pipes, valves, connections, and the like. Those pressure drops are often difficult to calculate beforehand, so practical experimentation is necessary in order to make the gas pressures equal between the various nozzle openings, which is costly in terms of time consumption. Also, changes in the piping, replacement of parts, and the like, will possibly affect the final nozzle opening gas pressures, making a recalibration necessary, which is also costly.
The present invention solves the above-described problems.
The present invention provides a direct flame impingement burner including a metal block and at least two nozzles projecting out from the metal block. Each of the nozzles includes a set of nozzle openings having at least one fuel opening and at least one oxidant opening. The set of openings in each nozzle is identical, including corresponding fuel and oxidant openings. The metal block has only one main fuel inlet and only one main oxidant inlet. The main oxidant inlet is connected to at least one main oxidant chamber, which is connected to at least one oxidant opening in the set of openings in each nozzle via apertures of identical length and cross section. The main fuel inlet is connected to at least one main fuel chamber, which is connected to at least one fuel opening in the set of openings in each nozzle via apertures of identical length and cross section. The gas pressure of fuel or oxidant is equal over all corresponding fuel and oxidant openings in the set of openings in each nozzle.
The expression “corresponding fuel and oxidant openings in every nozzle” refers herein to every corresponding fuel and oxidant opening, respectively, which is arranged in every respective set of openings in every nozzle. Thus, one such corresponding fuel or oxidant opening is present in exactly one instance in every nozzle.
The structure, operation, and advantages of the present invention will become further apparent upon consideration of the following description, taken in conjunction with the accompanying drawings in which:
A preferred embodiment of a burner in accordance with the present invention is shown in detail in
In
The burner 1 also includes two individual nozzles 3, 4, extending from a surface of the metal block 2. It should be noted, however, that it is not only possible, but in many applications desirable, to provide more than two individual nozzles in a burner in accordance with the present invention, in order to increase the surface area of the metallic material that can be heated uniformly and at the same time.
Every nozzle 3, 4 further includes a fuel opening 11 and oxidant openings 12a, 12b, through which fuel and oxidant are dispatched, respectively.
The fuel supply conduit 5 extends within the metal block 2 in the form of a channel and connects with a main fuel chamber 7 within the metal block. From the main fuel chamber 7, passageways 9 extend in the form of channels or conduits through the metal block 2, up to each nozzle 3, 4, and terminating at a fuel opening 11 in each of individual nozzles 3, 4.
The dimensions and the geometrical form of the main fuel chamber 7 are such that the gas pressure of the fuel inside the fuel chamber 7 is the same throughout the entire chamber 7. Notably, the fuel gas pressure inside the fuel chamber 7 is the same at the points where each passageway 9 opens into the fuel chamber 7. The cross-sectional area and the length of each passageway 9 are identical for passageways 9 serving different nozzles 3, 4 with fuel. Thus, the fuel gas pressure, and therefore also the flow velocity and volumetric flow of fuel at each fuel opening 11 are the same for each of different individual nozzles 3, 4.
In essentially the same way, the oxidant supply conduit 6 extends within the metal block 2 in the form of a channel. However, unlike the fuel supply conduit 5, the oxidant supply conduit 6 connects with each of two main oxidant chambers 8a, 8b. From the oxidant chamber 8a, passageways 10a extend in the form of channels or conduits through the metal block 2 up to each nozzle 3, 4, ending in an oxidant nozzle opening 12a in each individual nozzle 3, 4. At the same time, passageways 10b run, also in the form of channels through the metal block 2, from the main chamber 8b up to each nozzle 3, 4, and terminating at an oxidant opening 12b.
As is the case for the main fuel chamber 7 and the fuel-carrying passageways 9, the dimensions and geometrical form of the main oxidant chambers 8a, 8b are such that the gas pressure is the same at the points where the oxidant-carrying passageways 10a, 10b open into the respective main oxidant chambers 8a, 8b, and the length and cross-sectional area of the oxidant-carrying passageways 10a, 10b, respectively, are identical for each of different nozzles 3, 4, so that the oxidant gas pressure, flow velocity and volumetric flow are the same at the respective nozzle openings 12a, and at the respective nozzle openings 12b, for each of individual nozzles 3, 4.
Each individual nozzle 3, 4 thus includes a respective set of fuel and oxidant openings. The configuration of the set of openings of each individual nozzle 3, 4 is identical for each of different nozzles 3, 4.
The fuel- and oxidant-carrying passageways 9, 10a, 10b are coaxially arranged in an alternating manner, such that the passageways 9, 10a, 10b are arranged with one passageway inside another. When traversing the coaxially-arranged passageways 9, 10a, 10b from the inside to the outside, every other passageway is an oxidant-carrying passageway, and every passageway between adjacent oxidant passageways is a fuel-carrying passageway. Thus, the nozzle openings 11, 12a, 12b are also coaxially arranged in an alternating manner, such that the fuel and oxidant that are discharged from the nozzle openings 11, 12a, 12b form coaxially arranged fuel and oxidant cylinders or tubes, respectively. That arrangement maximizes the chemical reaction surface between the fuel and the oxidant when they are discharged from each individual nozzle 3, 4, which is preferred.
However, the invention is not limited to using one fuel opening 11 and two oxidant openings 12a, 12b, that are coaxially arranged in an alternating manner, as shown. The number and the arrangement of the fuel and the oxidant openings can thus be altered in any way suitable for the practical purpose of the embodiment, such as arranging the fuel and oxidant openings in a coaxial and alternating manner but providing more than one fuel opening together with more than one oxidant opening, or arranging the fuel and oxidant openings at a distance from each other in a non-coaxial manner.
The fact that the fuel and the oxidant flow into the metal block 2 through only two conduits 5, 6, respectively, and then through respective chambers and passageways running through the metal block 2, the amount of piping necessary is thus kept to a minimum. In fact, regardless of the number of individual nozzles 3, 4 that are provided, there is always only one fuel supply conduit 5 and one oxidant supply conduit 6. In that way the costs of production and maintenance of the burner 1 are minimized. Furthermore, the design of the burner 1 can be made extremely compact when using a single metal block 2 instead of a number of external pipes or conduits, which increases operational flexibility when positioning the burner 1 in a processing line or inside an industrial furnace.
The provision of main fuel and oxidant chambers 7, 8a, 8b, respectively, in cooperation with the passageways 9, 10a, 10b, ensures that the fuel and oxidant gas pressure, flow velocity, and volumetric flow at the corresponding nozzle openings 11, 12a, 12b are the same when comparing each corresponding nozzle opening 11, 12a, 12b between different individual nozzles 3, 4. That, in turn, ensures that the heating power of each individual nozzle 3, 4 is the same, despite the fact that only one common fuel supply conduit 5 and only one common oxidant supply conduit 6 is provided, making it possible to obtain a uniform heating profile over several individual nozzles 3, 4 in the same burner 1.
Furthermore, it is possible to alter the dimensions and geometrical forms of the main fuel chamber 7 and the main oxidant chambers 8a, 8b, as well as the dimensions of the passageways 9, 10a, 10b. For example, by making the outermost oxidant passageway 10b smaller in cross-sectional area than that of the innermost oxidant passageway 10a, for each nozzle 3, 4, less oxidant will be output through the outermost oxidant opening 12b in each nozzle 3, 4. In that way, the characteristics of the flame that is produced can be altered. However, because the flame characteristics for every nozzle 3, 4 are altered in the same way, the condition of uniformity is preserved even after such an alteration.
The main fuel and oxidant chambers 7, 8a, 8b in accordance with the present invention are not limited to serving only one corresponding fuel or oxidant nozzle opening 11, 12a, 12b in the set of openings in each nozzle 3, 4. It is possible to have one main oxidant chamber to provide with oxidant more than one oxidant opening in the set of openings in each nozzle 3, 4, for example.
An inexpensive and convenient way of producing the burner 1 of the present invention is to drill a number of cylindrical holes in the metal block 2, as can be seen in
Although particular embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit of the present invention. It is therefore intended to encompass within the appended claims all such changes and modifications that fall within the scope of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 0600901-3 | Apr 2006 | SE | national |
