JP3696351B2 - Regenerative burner - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat storage burner that supplies combustion air to a nozzle through a heat storage body and discharges combustion gas from the nozzle. More specifically, the present invention relates to an improvement in the nozzle of a regenerative burner.
[0002]
[Prior art]
In recent years, a regenerative burner that supplies combustion air to a nozzle through a heat storage body and discharges combustion gas from the nozzle is used as a heat source for an industrial furnace such as a heating furnace or a heat treatment furnace. In a heating furnace equipped with this regenerative burner, the burners are often arranged to face each other. For example, in the heating furnace 101 shown in FIG. 7, one furnace wall 101a and another furnace wall 101b facing each other are mutually connected. Opposing burners 102 are provided to burn each of the burners 102 and 102 alternately. Each burner 102 is connected to a single combustion air-cum-furnace high-temperature exhaust gas suction nozzle (simply abbreviated as “nozzle” in the present specification) 103 that performs switching between ejection of combustion air and suction of exhaust gas. Or, one heat storage body 111 (not shown) is provided. The heat storage body 111 is usually accommodated in the casing 110 and connected to the combustion air nozzle 103. However, depending on the case, the rear end portion of the combustion air nozzle itself may be enlarged to house the heat storage body. Further, a combustion air supply system 104, a combustion gas exhaust system 105, and a fuel supply system 106 are connected to each burner 102 via switching valves 107, 108, and 109, respectively.
[0003]
[Problems to be solved by the invention]
However, in the heat storage burner 102 shown in FIG. 7 described above, the arrangement of the burner is regulated by the outer shape of the heat storage body casing 110 of the burner (or the air throat outer shape in which the heat storage body is housed), so the combustion air nozzle 103 The interval between the burners must be equal to or greater than the outer shape of the burner, and it is difficult to arrange them in the furnace with a fine arrangement less than the outer dimensions of the burner. In addition, since the heat storage body 111, the combustion air supply system 104, and the switching valves 107 and 108 of the combustion gas exhaust system 105 are provided for each nozzle 103, the number of parts increases and the equipment cost increases. .
[0004]
In addition, when it is desired to change the combustion capacity between adjacent heat storage burners, burners having different combustion capacities must be arranged, and the size of the facility (industrial furnace) cannot be avoided. For example, in an upper and lower two-zone heating furnace that heats an object to be heated such as a horizontally mounted steel material from above and below with different combustion amounts, a regenerative burner that heats the upper belt and a regenerative burner that heats the lower belt Burners with different combustion amounts are provided. And control of heating temperature etc. is performed by operating separately the thermal storage type burner of each upper and lower belt | band | zone. In this case, since the burners having different combustion amounts are arranged, the number of parts increases correspondingly, and the equipment cost increases. Furthermore, the lower part of the object to be heated is supported by a walking beam, and cooling water is flowed inside the walking beam so that the strength can be maintained even when the surroundings are hot. For this reason, the heat load of the lower belt is larger than the upper belt by the heat loss due to the cooling water of the walking beam, so the heating temperature for the combustion load must be controlled separately in each belt, making the equipment more complicated This increases the equipment cost.
[0005]
Therefore, an object of the present invention is to provide a regenerative burner having a large degree of freedom in the installation position of the nozzle and having a low equipment cost.
[0006]
[Means for Solving the Problems]
In order to achieve such an object, the invention according to claim 1 is directed to a nozzle (combustion air / high temperature exhaust gas suction nozzle) that performs switching between ejection of combustion air and suction of exhaust gas, and air circulating through the nozzle. A heat storage burner that supplies combustion air to the nozzles and discharges combustion gas from the nozzles through the heat storage body, wherein the number of nozzles is greater than the number of heat storage bodies relative to the heat storage body. The number of nozzles greater than the number of the heat accumulators is provided for the heat accumulator, a header is provided between the heat accumulator and the number of nozzles larger than that, and the vicinity of each nozzle The fuel injection nozzles for injecting fuel to the nozzles are arranged so as not to protrude into the furnace, and the combustion air is jetted for each of the nozzles so as to have a predetermined air ratio, and the corresponding fuel jets nozzle Is the fuel amount and is set to be al ejected, and said nozzle are each made to correspond to the opening area of the nozzle with opening areas different from changing the fuel injection amount from the fuel nozzle, only the combustion capacity to form different flames Is.
[0007]
In this case, by disposing a larger number of combustion air nozzles than the number of heat storage bodies relative to the heat storage body, for example, by disposing a plurality of combustion air nozzles per heat storage body, A single burner can have the flame generating function of a plurality of burners. Accordingly, a plurality of nozzles can be installed in one window box, and a large number of nozzles can be continuously provided at an interval narrower than the width of the window box. Thereby, the freedom degree of the installation position of a nozzle is improved. In addition, since a plurality of nozzles can share a switching valve that switches between one heat storage body, combustion air ejection, and exhaust gas suction, the equipment cost is reduced due to a reduction in the number of parts. In this specification, “one heat storage body” means a single or a group of heat storage bodies filled in a wind box or a case connected to the wind box, and the flow path cross section of the above-mentioned wind box or the like. It does not indicate a piece of heat storage block that occupies a part of the heat storage block.
[0008]
In addition, by arranging a header, in particular, a header in which the flow passage cross-sectional area of the passing fluid is larger than the total cross-sectional area of the combustion air nozzle between the heat accumulator and the number of combustion air nozzles greater than the number of the heat accumulators. The air jet pressure and high-temperature gas suction pressure before each nozzle are equalized without any difference between the nozzles, so the nozzle jet air flow rate and exhaust gas suction flow rate are equal for each nozzle, and the jet amount and suction amount are It will be proportional to the nozzle cross-sectional area. Therefore, it is possible to make the combustion capacity in a single burner variable by providing nozzles having different opening areas and changing the nozzle cross-sectional area and changing the fuel injection amount from the fuel nozzle corresponding to this nozzle. It becomes possible. In other words, even if a common heat storage body or a switching valve that switches between combustion air ejection and exhaust gas suction is used, the amount of combustion air and fuel ejection varies from nozzle to nozzle so that they are adjacent to each other. The heating amount of the nozzle can be made different. That is, flames that differ only in combustion capacity are formed.
[0009]
In the heat storage burner according to the second aspect, the nozzle and the fuel ejection nozzle are arranged so that a flame is generated above and below the object to be heated, so that two independent flames are formed separately. . Therefore, even in the upper and lower two-zone heating furnace, a plurality of upper and lower nozzles can share a smaller number of heat accumulators and switching valves than the number of nozzles.
[0010]
Further, in the heat storage burner according to claim 3 , at least one of the nozzles is provided so as to eject the combustion air obliquely with respect to the furnace wall, and the combustion air is obliquely ejected from a single burner by a plurality of nozzles. And two independent flames are formed. Therefore, since the flame from the nozzle is formed obliquely with respect to the furnace wall, a flame is formed in a range wider than the installation range of the nozzle.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the configuration of the present invention will be described in detail based on an example of an embodiment shown in the drawings.
[0012]
As shown in FIG. 2, the heating furnace 1 of the present embodiment includes two sets of opposing heat storage burners 2. Each set of the regenerative burner 2 is arranged on both sides of the object to be heated on the transport zone (not shown) to constitute a heat storage type alternating combustion burner system so that a horizontal flame is formed along the object to be heated. Is provided.
[0013]
As shown in FIG. 1, each regenerative burner 2 includes a regenerator 3, a number of nozzles 4 and headers 16 that are larger than the number of regenerators 3. Specifically, three nozzles 4, 4, 4 are provided for one heat storage body 3. The header 16 is installed between the nozzle 4 and the heat storage body 3, distributes the combustion air from the heat storage body 3 to each nozzle 4, and sends the combustion gas from each nozzle 4 to the heat storage body 3 together. .
[0014]
The heat storage body 3, the nozzle 4, and the header 16 are provided in each part of the wind box 5. An upper vertical surface 5 a of the wind box 5 is exposed in the furnace 6. The nozzle 4 is configured by forming three through holes having equal opening areas side by side on the vertical exposed surface 5a. And the heat storage body 3 is accommodated in the center part of the wind box 5. FIG. As the heat accumulator 3, it is preferable to use a material having a large heat capacity and high durability, for example, a honeycomb-shaped tubular body formed of fine ceramics, although the pressure loss is relatively low, but it is not particularly limited to this, and other materials or You may use the thermal storage body 3 which consists of a structure. Normally, the heat storage element 3 is a combination of a small amount of fine ceramic-made honeycomb-shaped cylinders, but a single large block that fits in the wind box 5 is used in some cases. It is also possible to do.
[0015]
Further, a portion of the wind box 5 between each nozzle 4 and the heat storage body 3 constitutes a header 16. Here, it is preferable that the flow path cross-sectional area of the header 16 is set larger than the total opening area of the nozzles 4. A large space between the heat accumulator 3 and the plurality of nozzles 4, 4, 4 (a space where the flow passage cross-sectional area of the passing fluid is larger than the total cross-sectional area of the combustion air nozzle), that is, the arrangement of the header 16, The air jet pressure and the hot gas suction pressure before 4, 4 and 4 are equalized without any difference between the nozzles 4, 4 and 4. Accordingly, the nozzle ejection air flow rate and the exhaust gas suction flow rate are equal for each of the nozzles 4, 4, and 4, and the ejection amount and the suction amount are proportional to the nozzle cross-sectional area. Therefore, the combustion amount can be changed for each nozzle 4, 4 and 4 even within a single burner by increasing or decreasing the nozzle cross-sectional area and increasing or decreasing the fuel injection amount from the fuel nozzle corresponding to this nozzle. That is, even if the switching valve 9 or 10 that switches between the common heat accumulator 3 or combustion air ejection and exhaust gas suction is used, the combustion air and fuel ejection amounts differ for each of the nozzles 4, 4, and 4. The heating amount can be made different.
[0016]
Further, on the opposite side of the heat accumulator 3 that communicates with each nozzle 4, a combustion air supply system 7 that supplies combustion air to the wind box 5 and a combustion gas exhaust system 8 that discharges combustion gas are switchably connected. Has been. The combustion gas exhaust system 7 and the combustion air supply system 8 are respectively provided with switching valves 9 and 10 capable of intermittent flow.
[0017]
Here, the heat storage type alternating combustion burner system is not particularly limited in its structure and combustion system, and any structure can be used. In this embodiment, the heat storage body 3 and the burner 2 are used. The two are combined so that they are combusted alternately and are provided so that the exhaust gas can be discharged through the burner 2 and the heat accumulator 3 which are not combusted. For example, a combustion air supply system 7 for supplying combustion air to the windboxes 5 and 5 and a combustion gas exhaust system 8 for discharging combustion gas through the heat storage bodies 3 and 3 of the two burners 2 and 2, respectively. Connected to each burner 2, one burner 2 is provided so as to supply combustion air through the heat accumulator 3 and to discharge combustion gas from the other burner 2 through the heat accumulator 3.
[0018]
The systems 7 and 8 are selectively connected to the wind box 5 of one of the burners 2 by the switching valves 9 and 10, for example, combustion air supplied by the pushing fan 11 is supplied to the one wind box 5. At the same time as being supplied, the combustion gas is sucked from the other wind box 5 by the induction fan 12 and discharged into the atmosphere. In this embodiment, the switching valves 9 and 10 are provided in the respective systems 7 and 8, but the present invention is not limited to this, and a pair of opposed burners 2 and the respective systems 7 and 8 are connected to each other by a four-way valve. It doesn't matter.
[0019]
Further, in the vicinity of each nozzle 4, the fuel ejection nozzle 13 is exposed so as not to protrude into the furnace 6. The fuel injection nozzles 13 are connected to each other and connected to a fuel supply system 15 via a switching valve 14. This valve 14 selectively connects one of the heat storage type alternating combustion burner systems with the fuel supply system 15. Although not shown, the regenerative alternating combustion burner system is usually equipped with ancillary facilities such as a pilot burner and its ignition transformer. In addition, steam or water can be injected into the combustion air supply line as needed, and NOx suppression associated with preheating of the combustion air may be achieved.
[0020]
In the case of the present embodiment, the regenerative alternating combustion burner system is configured such that a pair of burners 2 and 2 are installed on opposing furnace walls 1a and 1b, and a pair of opposed burners, that is, a regenerative alternating combustion burner of two systems. Equipped with a system. In this case, fuel and combustion air are supplied to one burner 2, and combustion gas is discharged from the opposite burner 2. That is, when the burner 2 of one furnace wall 1a is burned, the burner 2 of the other furnace wall 1b is stopped, and the combustion gas is exhausted from the side of the stopped burner 2 to thereby exhaust the combustion gas from the heat storage body 3. The heat is recovered, and the heat is used for preheating the combustion air so as to be returned to the furnace 6 again.
[0021]
According to the present embodiment, since three nozzles 4 are formed in a single row in one wind box 5, the interval between the arrangement of adjacent nozzles 4 is made smaller than the horizontal width of the wind box 5. The degree of freedom of the installation position of the nozzle 4 is improved. For this reason, for example, when performing zone control in which the temperature distribution in the furnace is varied in a continuous heating furnace disclosed in Japanese Patent Laid-Open No. 5-118764, the accuracy of the temperature distribution in the furnace can be improved. At this time, the heating distribution can be changed by changing the setting of the opening area of the nozzle 4 to set the temperature distribution in the furnace 6.
[0022]
Moreover, according to this embodiment, since the three nozzles 4 are formed in one burner 2, the heat storage body 3 and each switching valve 9, 10, 14 can be shared by the three nozzles 4. For this reason, the installation number of the thermal storage body 3 and each switching valve 9,10,14 can be reduced, maintaining the quantity of the nozzle 4 as the whole heating furnace 1. FIG. Thereby, equipment costs can be reduced.
[0023]
By the way, since the number of the nozzles 4 should just be larger than the number of the thermal storage bodies 3, it is not restricted to what arrange | positions the three nozzles 4, 4, 4 with respect to one thermal storage body 3 like this embodiment. For example, three or more nozzles can be arranged for two heat storage bodies, or four or more nozzles can be arranged for three heat storage bodies. Also in this case, the number of installed heat storage bodies can be reduced while maintaining the number of nozzles, and the equipment cost can be reduced.
[0024]
On the other hand, in the present embodiment, the three nozzles 4 having the same opening area are formed in the wind box 5, but it is needless to say that the present invention is not limited to this. It is also possible to change the opening area for each nozzle or to arrange them vertically. For example, when it is desired to give a variation in the combustion amount load between a position above and below a certain horizontal plane, as shown in FIG. Two nozzles 4 and 4 are formed vertically. The lower nozzle 4 is formed with a larger opening area than the upper nozzle 4. The opening area of the fuel injection nozzle 13 near the lower nozzle 4 is larger than the opening area of the fuel injection nozzle 13 near the upper nozzle 4. Similarly, the opening area of the fuel nozzles 13 and 13 disposed in the vicinity of the nozzles 4 and 4 is also set to a value at which a fuel amount is injected so that a predetermined air ratio is obtained in accordance with the injection air amount. .
[0025]
According to the embodiment shown in FIG. 3, the heating amount by the lower nozzle 4 is larger than the heating amount by the upper nozzle 4. Therefore, as shown in FIG. 5, when the steel plate 17 is placed horizontally at the height between the upper and lower nozzles 4, 4 as an object to be heated, the lower portion of the steel plate 17 can be heated more strongly than the upper portion. Thereby, even if the thermal load below the steel plate is large by the walking beam 18 that supports the steel plate 17 from below, the furnace temperature can be made uniform, and the steel plate 17 can be heated from above and below with an equal amount of heat.
[0026]
3, the number of the heat storage bodies 3 and the switching valves 9, 10, 14 can be reduced while maintaining the number of nozzles 4 as a whole of the heating furnace 1. Of course, the cost can be reduced.
[0027]
Moreover, in each embodiment shown in FIG.1 and FIG.3, since the through-hole which comprises each nozzle 4 is formed perpendicularly | vertically with respect to the exposed surface 5a of the windbox 5, a flame with respect to the furnace walls 1a and 1b Of course, it is formed perpendicularly, but is not limited to a through hole perpendicular to the exposed surface 5a. For example, the through holes may be formed obliquely with respect to the furnace walls 1a and 1b or the exposed surface 5a. Specifically, as shown in FIG. 4, nozzles 4, 4 comprising two through holes arranged vertically in the furnace walls 1 a, 1 b are formed, and the upper nozzle 4 is formed obliquely upward toward the furnace 6. The lower nozzle 4 can be formed obliquely downward toward the furnace 6. Here, the lower nozzle 4 is formed to have a larger opening area than the upper nozzle 4. The opening area of the fuel injection nozzle 13 exposed in the furnace 6 near the lower nozzle 4 is made larger than the opening area of the fuel injection nozzle 13 exposed in the furnace 6 near the upper nozzle 4. Yes.
Therefore, when combustion air is ejected from each nozzle 4, 4, a flame is formed above the nozzle 4 from the upper nozzle 4 and from the lower nozzle 4, as shown in FIG. 5. A flame is formed below the nozzle 4. For this reason, a flame can be formed on the upper and lower sides of the steel plate 17 arranged horizontally at the same height as between the upper and lower nozzles 4, 4. Thereby, since the flame can be formed wider than the vertical width of the exposed surface 5a of the wind box 5, the size of the wind box 5 can be reduced.
[0028]
Further, as shown in FIG. 6, the fuel ejection nozzle 13 may be provided only at one place in the middle of the upper and lower nozzles 4, 4. In this case, fuel-rich combustion occurs near the fuel ejection nozzle 13 to form a reducing combustion gas. For this reason, as shown in FIG. 5, the steel plate 17 disposed horizontally at the same height as between the upper and lower nozzles 4 and 4 is surrounded by the reducing combustion gas and heated while its oxidation is suppressed.
[0029]
Even in the embodiment shown in FIGS. 4 and 6, the number of the heat accumulators 3 and the switching valves 9, 10, 14 can be reduced while maintaining the number of nozzles 4 as a whole in the heating furnace 1. Of course, the equipment cost can be reduced.
[0030]
The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the scope of the present invention. For example, in the embodiment shown in FIGS. 4 and 6, the nozzle 4 is ejected obliquely upward and obliquely downward, but in some cases, the nozzle 4 may be ejected in a direction inclined with respect to the surface to be heated in a horizontal plane.
[0031]
Furthermore, as other embodiment which arrange | positions the nozzle more than the number of this thermal storage body with respect to a thermal storage body, three or more nozzles are arrange | positioned with respect to two thermal storage bodies, or four or more with respect to three thermal storage bodies A nozzle may be arranged. Even in these cases, since more than one nozzle is arranged per one heat storage body, the degree of freedom of the nozzle installation position can be improved and the equipment cost can be reduced by reducing the number of parts.
[0032]
【The invention's effect】
As is clear from the above description, according to the first aspect of the present invention, a large number of nozzles can be continuously provided at an interval narrower than the width of the window box, so that the degree of freedom of the nozzle installation position is improved. . Moreover, since the nozzles can be arranged at a narrow interval, temperature zone control in a narrow range is possible, and for example, zone control in a continuous heating furnace can be performed with high accuracy. Further, since the switching valve for switching between one heat storage body, combustion air ejection and exhaust gas suction can be shared by a plurality of nozzles, the equipment cost can be reduced by reducing the number of parts. Furthermore, the combustion capacity in a single burner can be made variable by changing the nozzle cross-sectional area and changing the fuel injection amount from the fuel nozzle corresponding to this nozzle to form a flame that differs only in the combustion capacity. It becomes possible. In other words, even if a common heat storage body or a switching valve that switches between combustion air ejection and exhaust gas suction is used, the amount of combustion air and fuel ejection varies from nozzle to nozzle so that they are adjacent to each other. The heating amount of the nozzle can be made different.
[0033]
In the heat storage burner according to the second aspect, the nozzle and the fuel ejection nozzle are arranged so that a flame is generated above and below the object to be heated, and two independent flames are formed separately on the top and bottom. Even in a two-zone heating furnace, a plurality of upper and lower nozzles can share a smaller number of heat storage bodies and switching valves than the number of nozzles, and the equipment cost can be reduced by reducing the number of parts.
[0034]
According to a third aspect of the present invention, at least one of the nozzles is provided so that the combustion air is ejected obliquely with respect to the furnace wall, and the combustion air is ejected obliquely by a plurality of nozzles from one burner. Since two independent flames are formed, the flame from the nozzle is formed obliquely with respect to the furnace wall, and a flame can be formed in a wider range than the installation range of the nozzle. For this reason, since the installation range of a nozzle can be made smaller than the range which forms a flame, size reduction of a burner can be achieved.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an embodiment of a heat storage burner according to the present invention.
FIG. 2 is a schematic view showing an example of a heating furnace burner system using a regenerative burner.
FIG. 3 is a perspective view showing another embodiment of a heat storage burner.
FIG. 4 is a cross-sectional view showing another embodiment of a heat storage burner.
FIG. 5 is a schematic view showing a heating furnace using another embodiment of a regenerative burner.
FIG. 6 is a cross-sectional view showing still another embodiment of a heat storage burner.
FIG. 7 is a schematic view showing an example of a heating furnace burner system using a conventional heat storage burner.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Heating furnace 2 Thermal storage burner 3 Thermal storage body 4 Nozzle 16 Header 17 Steel plate (to-be-heated object)

Claims (3)

A nozzle that performs switching between ejection of combustion air and suction of exhaust gas, and a heat storage body through which air flowing through the nozzle is circulated, and supply of combustion air to the nozzle through the heat storage body and from the nozzle In a heat storage burner that discharges combustion gas, a larger number of nozzles than the number of the heat storage bodies are provided for the heat storage body, and a header is provided between the heat storage body and the nozzles having a larger number of the nozzles. Combustion air that is provided in the vicinity of each nozzle and is exposed so as not to protrude into the furnace so that fuel is ejected in the vicinity of each nozzle, and is ejected for each nozzle so as to have a predetermined air ratio; set the amount of fuel ejected from said respective fuel injection nozzles corresponding thereto, and the nozzle from the fuel nozzle, each opening area is corresponding to the opening area of the nozzle with different Changing the fuel injection amount, regenerative burners only combustion capacity is to form different flames.   The regenerative burner according to claim 1, wherein the nozzle and the fuel ejection nozzle are arranged so that a flame is generated above and below the object to be heated, and two independent flames are formed separately in the upper and lower sides. At least one of the nozzles is provided so as to eject combustion air obliquely with respect to the furnace wall, and combustion air is obliquely ejected from a single burner by a plurality of nozzles to form two independent flames. The regenerative burner according to claim 1 or 2, wherein

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