WO2018180694A1

WO2018180694A1 - Heating device and heating method

Info

Publication number: WO2018180694A1
Application number: PCT/JP2018/010774
Authority: WO
Inventors: 透理堀川; 一晃原; 好司岩田
Original assignee: Ｊｆｅスチール株式会社
Priority date: 2017-03-27
Filing date: 2018-03-19
Publication date: 2018-10-04
Also published as: CN110325794B; JP6690779B2; EP3604925B1; JPWO2018180694A1; TW201839342A; TWI670457B; KR102273957B1; CN110325794A; EP3604925A1; EP3604925A4; KR20190113899A

Abstract

Provided is a heating device with which it is possible to maintain a flame in a stable manner without flameout even at high discharge speeds, and to carry out heating with extremely high efficiency. A heating device provided with a burner, wherein the burner comprises: a main burner part provided with a fuel gas nozzle for discharging a fuel gas and an air nozzle for discharging air for combustion; and a pilot burner part for combusting the fuel gas discharged from the main burner part, the pilot burner part being positioned further outward than the main burner part.

Description

Heating apparatus and heating method

The present invention relates to a heating apparatus including a burner, and more particularly to a heating apparatus that can stably hold a flame without misfire even at a high discharge speed and can perform heating with extremely high efficiency. The present invention also relates to a heating method using the heating device.

As a method for heating an article, various methods such as hot air heating, infrared heating, heating with an electric heater, induction heating, and the like are known. Among them, heating with a burner is very commonly used in various applications.

FIG. 8 is a schematic view showing an example of a premixed combustion burner conventionally used. In the premixed combustion burner 100, combustible fuel gas 101 and air 102 are premixed in the premixed combustion burner 100 to form a mixed gas, and the mixed gas is discharged from the premixed combustion burner 100 and burned. As a result, a flame 103 is formed.

When direct heating is performed using a flame formed by such a burner, the heat transfer amount Q from the flame to the surface of the object to be heated is proportional to the heat transfer coefficient α, and the heat transfer coefficient α is equal to the flame discharge speed V ₀ . Dependent. For example, when a burner having a circular opening is used, the heat transfer coefficient α is proportional to V ₀ ^1/2 . In the case of a line burner in which a plurality of nozzles are arranged in a straight line, the heat transfer coefficient α is proportional to V ₀ ^0.58 . Therefore, in order to improve the heating efficiency by the burner, it is required to increase the discharge speed.

However, simply increasing the flow rate of fuel gas or air to increase the discharge speed makes the flame unstable, and if the flow rate is further increased, the balance between the combustion speed and the gas flow rate is broken, and the flame is blown off downstream and disappears. So-called blowout occurs. For this reason, the conventional burner cannot greatly increase the discharge speed, and thus there is a limit to the improvement of the heating efficiency.

Therefore, as a method for stabilizing the flame and suppressing the blow-off, there has been proposed a method using a burner including a main burner and a sleeve fire burner for assisting combustion in the main burner (Patent Document 1).

JP 2013-194991 A

According to the burner of Patent Document 1, it is possible to stabilize the flame and raise the flame temperature. However, the burner proposed in Patent Document 1 is not sufficient in terms of improving the discharge speed described above, and is provided with a burner that can be used stably at a higher discharge speed in order to improve heating efficiency. Development of a new heating device is required.

The present invention has been made in view of the above circumstances, and can provide a heating apparatus that can stably hold a flame without misfire even at a high discharge speed and can perform heating with extremely high efficiency. The purpose is to provide. Another object of the present invention is to provide a heating method using the heating device.

As a result of investigations to solve the above problems, the present inventors have used a burner in which a main burner portion and a sleeve fire burner portion are provided in a specific positional relationship, for example, an extremely high value of 50 Nm / s or more. It was found that the flame can be held stably even at a high discharge speed. This invention is made | formed based on the said knowledge, The summary structure is as follows.

1. A heating device comprising a burner,
The burner
A main burner section comprising a fuel gas nozzle for discharging fuel gas and an air nozzle for discharging combustion air;
A heating apparatus, comprising: a sleeve fire burner portion that is located outside the main burner portion and burns fuel gas discharged from the main burner portion.

2. The heating apparatus according to claim 1, wherein the main burner section includes a pressure equalizing chamber on the upstream side of one or both of the fuel gas nozzle and the air nozzle.

3. 3. The heating apparatus according to 1 or 2, wherein the fuel gas nozzle and the air nozzle have a straight pipe structure.

4). A concave portion having a bottom portion and a tapered portion gradually widening from the bottom portion toward the tip of the burner is provided at the tip of the burner,
The main burner portion is disposed at the bottom;
The heating apparatus according to any one of claims 1 to 3, wherein the sleeve fire burner portion is disposed in the tapered portion.

5. 5. The heating device according to 4 above, wherein an angle θ formed by the bottom portion and the tapered portion is 20 ° or more.

6). 6. The heating apparatus according to any one of 1 to 5, wherein the sleeve fire burner is a surface combustion burner.

7). The flaming burner comprises a flaming nozzle selected from a tubular nozzle having a diameter d and a slit nozzle having a width d in the short side direction;
6. The heating apparatus according to 4 or 5 above, wherein a tip of the flaming nozzle is provided at a position deeper than d and not more than 15d from the surface of the tapered portion.

8). The heating apparatus according to any one of the above 1 to 7, further comprising a flow rate adjusting means capable of independently adjusting a flow rate in the main burner portion and a flow rate in the sleeve fire burner portion.

9. A heating method of heating using the heating apparatus according to any one of 1 to 8 above.

10. 10. The heating method according to 9 above, wherein the discharge speeds of the fuel gas and the combustion air discharged from the main burner part are 50 Nm / s or more.

11. The ratio of the flow rate F1 of the fuel gas discharged from the main burner portion to the flow rate F2 of the fuel gas for the sleeve fire discharged from the sleeve fire burner portion, F1: F2, is set to 70:30 to 85:15. Item 11. The heating method according to Item 9 or 10.

According to the present invention, it is possible to stably hold a flame without misfire even at a high discharge speed, and heating can be performed with extremely high efficiency.

It is a schematic diagram which shows the structure of the burner in one Embodiment of this invention. It is a schematic diagram which shows the structure of the main burner part in one Embodiment of this invention. It is a schematic diagram which shows the structure of the sleeve fire burner part in one Embodiment of this invention. It is a schematic diagram which shows the structure of the sleeve fire burner part in other embodiment of this invention. It is a figure which shows the discharge speed in each burner of an Example and a comparative example. It is a figure which shows the heating power in each burner of an Example and a comparative example. It is a figure which shows the example of a measurement of the temperature distribution in the burner of the comparative example 1 and Example 1. FIG. It is a schematic diagram which shows an example of the conventional premixed combustion burner.

Next, a method for carrying out the present invention will be specifically described. In addition, the following description shows the suitable embodiment of this invention, and this invention is not limited at all by the following description.

The heating device of the present invention is a heating device including a burner, and the burner includes a main burner portion and a sleeve fire burner portion. The main burner section includes a fuel gas nozzle that discharges fuel gas and an air nozzle that discharges combustion air, and the fuel gas and air discharged from the main burner section are combusted. To form a flame for heating. The sleeve fire burner portion has a function for igniting the fuel gas discharged from the main burner portion.

Here, it is important that the sleeve fire burner portion is positioned outside the burner with respect to the main burner portion. By adopting such a positional relationship, it is possible to stably hold the flame even at a higher discharge speed as compared with other positional relationships. As described above, the heat transfer amount Q from the flame to the surface of the object to be heated is proportional to the heat transfer coefficient α, and the heat transfer coefficient α increases as the flame discharge speed V ₀ increases. Therefore, according to the heating device of the present invention, heating can be performed with extremely high efficiency by causing a flame to collide with the surface of the object to be heated at high speed. As a result, the object to be heated can be heated to a higher temperature at a higher speed. Moreover, according to the heating device of the present invention, the amount of fuel gas necessary to achieve the same heating temperature can be reduced. Furthermore, since the discharge speed can be increased in the heating device of the present invention, the flame can reach a distant position. Therefore, the burner can be installed at a position away from the object to be heated, and the degree of freedom in device design is high.

Especially in the steelmaking process, it is often necessary to heat an object to be heated located away from the burner. Therefore, the heating device of the present invention can be used very suitably as a heating device for an iron making process for heating an iron making material. Examples of the heating device for the iron making process include an ignition device for a sintering machine used for producing sintered ore. Moreover, when using the heating apparatus of this invention as a heating apparatus for iron-making processes, it is preferable that the structure of a burner is a line burner provided with the several nozzle arranged in a linear form.

In addition, it is estimated that the flame can be stably maintained even at a high discharge speed by using the above-described positional relationship for the following reason. That is, as proposed in Patent Document 1, the fuel gas nozzle and the combustion air nozzle are arranged so as to sandwich the squib burner, and the fuel gas discharge direction and the combustion air discharge direction are arranged to intersect each other. In this case, a vortex flow is generated, and the kinetic energy loss due to the flow turbulence increases, so that a high flow velocity cannot be maintained. On the other hand, in the technology of the present invention, the sleeve fire burner portion is located outside the burner with respect to the main burner portion, thereby suppressing the turbulence of the flow of the mainstream fuel gas and combustion air, and the high flow rate. Can be maintained. Further, if the discharge direction of the fuel gas discharged from the main burner portion and the combustion air are made parallel, the flow disturbance can be further suppressed and a higher flow rate can be maintained.

In addition, when the fuel gas nozzle is located in the center, the squib burner is arranged outside, and the combustion air nozzle is arranged outside the fuel gas nozzle, it is necessary to discharge the fuel gas toward the scabs on both sides. Is required on both sides. As a result, since the number of nozzles increases and the discharge speed is increased, the diameter of each nozzle is reduced, so that the attenuation of the gas speed after discharge increases and the high flow rate after discharge cannot be maintained. On the other hand, in the technique of the present invention, since it is not necessary to divide the fuel gas on both sides, a high flow rate can be maintained.

[Fuel gas]
The fuel gas is not particularly limited, and any flammable gas can be used. As the fuel gas, for example, natural gas or LPG (liquefied petroleum gas) can be generally used. When the heating device is used in a steelworks, a process gas by-produced in the steelworks can be used as the fuel gas. As the process gas, it is preferable to use a process gas containing a coke oven gas. As the process gas containing the coke oven gas, for example, the coke oven gas itself (that is, a gas composed only of the coke oven gas) and M gas that is a mixture of coke oven gas and blast furnace gas are preferably used. .

Next, more specific explanation will be given based on the drawings.

FIG. 1 is a schematic diagram of a burner 1 according to an embodiment of the present invention, and shows a structure of a cross section of the burner 1. The burner 1 includes a burner body 10, and a main burner portion 20 and a sleeve fire burner portion 30 provided on the burner body 10. A recess 40 is provided at the tip of the burner 1 (on the side where the flame is formed). The recess 40 includes a bottom 41 and a tapered portion 42 that gradually widens from the bottom 41 toward the tip of the burner 1. Have.

[Main burner section]
FIG. 2 is a schematic diagram showing the structure of the main burner portion 20 in one embodiment of the present invention. The main burner unit 20 includes a fuel gas nozzle 21 that discharges fuel gas and an air nozzle 22 that discharges combustion air. One fuel gas nozzle 21 is provided at the center of the bottom 41. Two air nozzles 22 are provided symmetrically so as to sandwich the fuel gas nozzle 21 therebetween. In addition, although the cross section of one burner is shown in the example shown in FIG. 2, when a wide article is heated, it is preferable to arrange a plurality of burners in the direction perpendicular to the paper surface to form a line burner.

Fuel gas is supplied as indicated by arrow G and is discharged from the fuel gas nozzle 21. Combustion air is supplied as indicated by arrow A and is discharged from the air nozzle 22. The fuel gas is not ignited at the time of discharge, but is ignited by the sleeve fire 50 formed by the sleeve fire burner 30 as shown in FIG.

The shape of the fuel gas nozzle 21 and the air nozzle 22 is not particularly limited, and can be any shape. However, as shown in FIG. 2, it is preferable to use a straight pipe structure that does not have a cone-like structure at the nozzle tip. If a straight tube structure nozzle is used, the discharge rate can be further improved and the heat transfer coefficient on the heated surface can be further increased. As a result, the heating efficiency can be further improved. This is because the straight pipe structure nozzle has less energy loss due to the vortex formation than the nozzle that forms the swirl flow, and the gas velocity after discharge is suppressed from being attenuated.

The diameters of the fuel gas nozzle 21 and the air nozzle 22 (hereinafter referred to as nozzle diameter) are preferably determined so that the discharge flow rate in the normal use flow rate range is 50 to 80 Nm / s in order to increase the heating efficiency of the burner. Further, the discharge flow rate during maximum combustion is preferably 150 Nm / s or less. The definition of the discharge speed will be described later.

The specific diameters of the fuel gas nozzle 21 and the air nozzle 22 are not limited, but if the diameter is 3 mm or more, attenuation of the gas velocity after being discharged from the nozzle can be further suppressed. Therefore, the diameter is preferably 3 mm or more, and more preferably 5 mm or more. On the other hand, the condition of the diameter is not particularly limited, but if the diameter is 30 mm or less, the heat load of the burner can be maintained in a more preferable range, and the life of the burner can be extended. Also, by providing a large number of small diameter nozzles having a diameter of 30 mm or less, heating can be performed more uniformly than when a small number of large diameter nozzles are provided. Therefore, the diameter is preferably 30 mm or less. The diameter of the fuel gas nozzle 21 and the diameter of the air nozzle 22 may be the same or different.

The distance (nozzle pitch) L ₁ between the fuel gas nozzle 21 and the air nozzle 22 is 2d _NG ≦ L ₁ ≦ 15d _NA when the diameter of the fuel gas nozzle 21 is d _NG and the diameter of the air nozzle 22 is d _NA. It is preferable to satisfy. When a plurality of burners are arranged to form a line burner, it is preferable that the fuel gas nozzle interval (nozzle pitch) L ₂ of each burner satisfies 2d _NG ≦ L ₂ ≦ 15d _NA . If the above conditions are satisfied, combustion stability is further improved, and attenuation of gas velocity can be further suppressed.

[Equal pressure chamber]
The main burner portion 20 is provided with a pressure equalizing chamber 23 on the upstream side of each of the fuel gas nozzle 21 and the air nozzle 22, and fuel gas or air passes on the opposite side (upstream side) of the nozzle of the pressure equalizing chamber 23. A perforated plate 24 provided with holes is provided. If the pressure equalizing chamber 23 is provided in this way, the gas can be discharged more uniformly, so that the flame can be further stabilized and the discharge speed can be further increased. Note that the pressure equalizing chamber 23 can be provided only on the upstream side of one of the fuel gas nozzle 21 and the air nozzle 22, but it is preferable to provide the pressure equalizing chamber 23 on both as shown in FIG. Here, the pressure equalizing chamber is a structure provided on the upstream side of the nozzle in order to mitigate the influence of fluctuations in gas supply pressure. As illustrated in FIG. 2, the pressure equalization chamber includes a plate (throttle plate) provided on the upstream side of the nozzle and having one or more openings, and a space between the throttle plate and the nozzle. Is provided. The upstream side of the diaphragm plate and the space are connected only by the opening of the diaphragm plate. The total area of the openings provided in the diaphragm plate is smaller than the cross-sectional area of the space in a plane perpendicular to the discharge direction of the nozzle. Furthermore, the total area of the nozzle openings is also smaller than the cross-sectional area of the space in a plane perpendicular to the nozzle ejection direction.

[Sleeve Burner]
As described above, the sleeve fire burner portion has a function of igniting the fuel gas discharged from the main burner portion and burning the fuel gas. The ignition of the fuel gas discharged from the main burner portion is performed by a flame (sleeve fire) formed by the sleeve fire burner portion. Therefore, the sleeve fire burner section normally includes a sleeve fire fuel gas outlet and a sleeve fire air outlet for forming a sleeve fire. A sleeve fire is formed by burning the fuel gas for the sleeve fire using the air for the sleeve fire. In the following description, “sleeve fire fuel gas” may be simply referred to as “fuel gas”, and “sleeve fire air” may be simply referred to as “air”.

Since the heating device of the present invention includes the sleeve fire burner for burning the fuel gas discharged from the main burner outside the main burner as described above, the fuel gas from the main burner The flame can be stably maintained even under conditions where the discharge speed is high. Therefore, the burner of the present invention has a combustion chamber structure for stably maintaining a flame on the front side of the main burner, that is, a structure protruding toward the front of the burner so as to surround the main burner and the sleeve fire burner. There is also an advantage that it is not necessary.

Further, in the heating device of the present invention, the flame of the main burner is maintained in the space portion in front of the gas discharge direction from the main burner. In the known technology, a combustion chamber structure for stably maintaining a flame or a cone-shaped structure composed of a refractory is provided on the front side of the main burner, and the flame is maintained inside or on the surface thereof. In the present invention, it is possible to maintain the flame of the main burner in the space with the flame of the sleeve fire burner without providing such a structure, so that the high speed of the main burner can be maintained. The flame can be maintained. In order to maintain such a flame, the intersection of the gas discharge direction of the main burner portion and the gas discharge direction of the sleeve fire burner portion is the outside of the space portion in front of the gas discharge direction of the burner or the recess of the burner ( It is preferably located outside the burner.

FIG. 3 is a schematic diagram showing the structure of the sleeve fire burner 30 in one embodiment of the present invention. In this example, the sleeve fire burner 30 is composed of a surface combustion burner. A porous plate 31 is provided at the tip of the surface combustion burner, and fuel gas for sleeve fire and air for sleeve fire are supplied to the porous plate 31 as indicated by arrows G and A, respectively.

In the heating device of the present invention, since the fuel gas and air are discharged from the main burner portion 20 at high speed, an accompanying flow accompanying the air flow is formed near the tip of the burner 1, particularly in the recess 40. For example, when the flow rate of the gas discharged from the main burner portion is 50 m / s, the flow rate of the accompanying flow is as high as 20 to 30 m / s, so the sleeve fire 50 formed by the sleeve fire burner portion 30 is unstable. There is a risk of becoming. However, in the surface combustion burner, since the ignition point exists on the surface or inside of the porous plate, the sleeve fire can be stably held without being affected by the accompanying flow.

The porous plate 31 is not particularly limited, and a plate-like member made of an arbitrary porous body can be used. The porous body can be made of, for example, one or more materials selected from the group consisting of metals, alloys, and ceramics. As the porous plate 31, for example, a metal mesh (a laminate of metal fibers) can be used. The surface of the porous plate 31 is preferably disposed on the same plane as the surface of the tapered portion 42.

As shown in FIG. 1, the fuel gas and air discharged from the main burner unit 20 are ignited by a sleeve fire 50. Therefore, from the viewpoint of surely igniting, the main burner portion 20 and the sleeve fire burner portion 30 have a discharge axis (discharge direction) of the main burner portion 20 and a discharge axis (discharge direction) of the sleeve fire burner portion 30. It is preferable that they are arranged so as to intersect on the extension line. More specifically, it is preferable that the angle θ formed by the bottom portion 41 and the tapered portion 42 constituting the recess 40 is 20 ° or more. If the angle θ is less than 20 °, the flame of the sleeve fire burner part is difficult to reach the gas flow discharged from the main burner part, and misfire is likely to occur. The θ is more preferably 30 ° or more. On the other hand, the upper limit of the θ is not particularly limited, but is usually preferably 80 ° or less, and more preferably 60 ° or less.

The distance between the main burner portion and the sleeve fire burner portion is determined so that the flame of the sleeve fire burner portion (sleeve fire 50) reaches the discharge flow from the main burner portion. When the effective flame length of the sleeve fire burner is F, the distance that the flame of the sleeve fire burner reaches in the direction parallel to the surface of the bottom 41 is F · sin θ. The distance between the main burner portion and the sleeve fire burner portion may be determined so that the distance from the center position of the sleeve fire burner portion is F · sin θ or less in the direction parallel to the surface of the bottom portion 41. Specifically, when the effective flame length of the sleeve burner portion is 100 mm, the width of the main burner (the distance between the outermost nozzles of the main burner portion) is 50 mm, and θ = 30 °, the center of the main burner portion and the sleeve flame The distance at the center of the burner may be 75 mm or less. Considering a preferable range of θ, it is preferable that the distance between the center of the main burner portion and the center of the sleeve burner portion is 60 to 110 mm. The effective flame length can be determined as the length from the combustion surface or the taper surface of the region that is equal to or higher than the gas ignition temperature based on the measurement result of the flame temperature.

FIG. 4 is a schematic view showing an example of the structure of the sledge fire burner portion in another embodiment of the present invention. In this embodiment, the sleeve fire burner 30 includes a tubular nozzle having a diameter d as the sleeve fire nozzle 32. The sleeve fire nozzle 32 includes an outer pipe and an inner pipe provided coaxially. As shown by an arrow G, the sleeve fire fuel gas is supplied to the inner pipe. It is discharged from the tip of the inner tube. On the other hand, as shown by the arrow A, the sleeve fire air is supplied to the outer pipe, and the sleeve fire air is discharged from the tip of the outer pipe.

The tip of the sleeve fire nozzle 32 is provided at a position deeper than d from the surface of the tapered portion 42 as shown in FIG. In other words, the distance from the surface of the taper portion 42 to the tip of the sleeve nozzle 32 is d or more. The fuel gas for sleeve fire discharged from the sleeve fire nozzle 32 is ignited in the space 33, and the flame (sleeve) is formed so as to extend beyond the surface of the tapered portion 42. In this way, by setting the tip of the sleeve fire nozzle 32 to a position recessed toward the inside of the burner body 10, the effect of the accompanying flow described above can be suppressed and the sleeve fire can be stabilized without using a surface combustion burner. It becomes possible to hold. Even when the sleeve fire burner portion 30 includes a slit nozzle having a width d in the short side direction as the sleeve fire nozzle 32, the tip of the sleeve fire nozzle 32 is similarly recessed at least d from the surface of the tapered portion 42. It is preferable to provide it. From the viewpoint of suppressing the influence of the accompanying flow, the distance from the surface of the tapered portion 42 to the tip of the sleeve fire nozzle 32 is preferably 2d or more. On the other hand, if the tip of the sleeve fire nozzle 32 is installed at a position deeper than the surface of the tapered portion 42 by 15 d or more, the flame temperature may be lowered. For this reason, the distance from the surface of the tapered portion 42 to the tip of the sleeve fire nozzle 32 is preferably 15 d or less, and more preferably 4 d or less.

[Discharge speed]
As described above, according to the heating device of the present invention, it is possible to stably hold a flame without misfire even at a high discharge speed, and it is possible to perform heating with extremely high efficiency. In addition, the discharge speed at the time of use is not particularly limited and may be any speed as long as the flame can be held. From the viewpoint of heating efficiency, the fuel gas and air discharged from the main burner section The discharge speed of each is preferably 50 Nm / s or more, more preferably 60 Nm / s or more, and still more preferably 65 Nm / s or more. Thus, an extremely high discharge speed cannot be realized by a conventional burner.

Here, the discharge speed is the gas flow velocity in the fuel gas nozzle of the main burner section and the straight pipe section of the air nozzle, and is determined by discharge speed = gas flow rate per unit time of a single nozzle / nozzle cross-sectional area. In a nozzle that does not have a straight pipe portion, the cross-sectional area of the nozzle outlet portion is considered as the nozzle cross-sectional area. Further, in the case of a burner composed of a number of nozzles or a number of holes and having a conical cone portion in front of the nozzle as illustrated in FIG. 8, the fuel discharged from the burner with a cross-sectional area at the outlet of the cone portion. By dividing the total flow rate of the sum of gas and air, the burner discharge speed can be determined.

It is preferable that the fuel gas discharge speed and the combustion air discharge speed be approximately equal. Specifically, the ratio of the discharge speed of the fuel gas to the discharge speed of the combustion air (discharge flow rate ratio) is preferably 0.8 to 1.2. Even in a burner having a conical cone, the discharge flow rate ratio in the nozzle hole portion in front of the cone is preferably 0.8 to 1.2.

[Fuel gas flow ratio]
The ratio of the fuel gas flow rate in the main burner portion and the fuel gas flow rate in the sleeve fire burner portion (hereinafter also referred to as “fuel gas flow rate ratio”) greatly affects the flame stability and the heating capacity. Therefore, it is preferable that the heating device includes a flow rate adjusting unit that can independently adjust the fuel gas flow rate in the main burner portion and the fuel gas flow rate in the stagfire burner portion. The combustion air amount can be determined by multiplying the fuel gas flow rate by the theoretical amount of fuel gas and the air ratio. It is preferable that the heating device includes a flow rate adjusting unit that can independently adjust the flow rate of the combustion air in the main burner portion and the flow rate of the combustion air in the sleeve fire burner portion. As the flow rate adjusting means, a flow rate adjusting valve or the like can be used.

When the sum of the fuel gas flow rate in the main burner portion and the fuel gas flow rate in the sleeve fire burner portion is 100%, if the sleeve gas burner portion fuel gas flow rate is less than 15%, the flame temperature due to the accompanying flow is significantly reduced. A primary burner misfire may occur. Therefore, it is preferable that the flow rate of the fuel gas in the sleeve fire burner is 15% or more. In other words, the ratio of the flow rate F1 of the fuel gas discharged from the main burner portion to the flow rate F2 of the fuel gas for sleeve fire discharged from the sleeve fire burner portion, F1: F2 is 85:15 or less (F1 / F2 ≦ 85/15). On the other hand, if the flow rate of the fuel gas in the sleeve fire burner portion is too large, the flame is stabilized, but the flame in the main burner portion is reduced, so that the heating capacity is lowered. Therefore, it is preferable that the flow rate of fuel gas in the flaming burner portion is 30% or less, in other words, F1: F2 is 70:30 or more (F1 / F2 ≧ 70/30).

In order to confirm the influence of the burner structure on the flame stability, the following three types of burners were used to evaluate the critical discharge speed at which the flame can be held without blowing out.
(Comparative Example 1) Conventional general premixed combustion burner shown in FIG. 8 (Comparative Example 2) Burner shown in FIG. 1 of Patent Document 1 (Example 1) Burner having the structure shown in FIGS.

In the above examples and comparative examples, the width of the burner in the direction perpendicular to the cross section shown in FIGS. Table 1 shows the dimensions of the nozzle and the cross-sectional area of the discharge part. Further, the ratio of the flow rate of the fuel gas in the main burner portion and the flow rate of the fuel gas in the sleeve fire burner portion in Comparative Example 2 and Example 1 (fuel gas flow rate ratio) is shown in Table 1 together.

In Comparative Example 1, a slit-shaped nozzle having the cross-sectional shape shown in FIG. 8 and having a nozzle width of 10 mm and a length of 1 m was used. In Comparative Example 2, 60 nozzles set in a straight line between 1 m in the burner width direction were used as shown in FIG. Since the burner described in Patent Document 1 includes two fuel gas nozzles per burner, the number of fuel gas nozzles is 120. In Example 1, 50 nozzle sets of the nozzles of FIGS. 1 and 2 according to the present invention were linearly arranged in the burner width direction 1 m, that is, 50 fuel gas nozzles were installed. When 50 sets of nozzles were arranged in the burner of Comparative Example 2, the flame was unstable, so 60 sets of nozzles were installed to stabilize the flame.

The experiment was conducted in an experimental combustion furnace having a combustion space size of 1.4 m × 1.4 m × 0.4 m. The flow rate of the fuel gas and the combustion air was increased so that the flow rate ratio was constant, and the critical discharge flow rate at which the flame could be held without the flame blowing out was measured.

Here, as the fuel gas, M gas (mixed gas of coke oven gas and blast furnace gas), which is a by-product gas in the steelworks, was used. The main components of the M gas were H ₂ : 26.5%, CO: 17.6%, CH ₄ : 9.1%, and N ₂ : 30.9%.

The measurement results are shown in FIG. In Comparative Example 1, when the flow velocity (discharge speed) in the nozzle straight pipe portion exceeded 30 Nm / s, the flame could not be held and blowing out occurred. The flow rate of the straight pipe portion is 3 Nm / s when converted to the flow velocity at the tip of the cone portion. In Comparative Example 2, when the flow velocity (discharge speed) in the nozzle straight pipe portion exceeded 40 Nm / s, the flame could not be held and blowing out occurred. On the other hand, in Example 1, the flame was stable even under conditions where the discharge speed exceeded 40 Nm / s. When the discharge speed exceeded 100 Nm / s, the flame became unstable and blow-off occurred at 120 Nm / s.

From the above results, it can be seen that the heating apparatus of the present invention can perform stable combustion even at a discharge flow rate significantly higher than that of a conventional burner. In addition, when using the burner of the present invention for industrial use etc., use near the blow-off limit flow rate may increase the risk of blow-off due to fluctuations in the operation of the supply system, etc. However, it is preferable that the flow rate be reduced. FIG. 5 also shows an example of the actual normal use flow rate.

Also, simultaneously with the above measurement, a water-cooled chiller simulating an object to be heated was installed at a position 0.4 m away from the burner, and the heating power of the burner was evaluated from the rising temperature of the water. FIG. 6 shows the heating power of the burner in each example and comparative example when the fuel gas flow rate and the air ratio are the same. In Example 1, it turns out that a heating power is improving significantly compared with the comparative example 1 and the comparative example 2.

Furthermore, simultaneously with the above measurement, the flame temperature distribution in Comparative Example 1 and Example 1 was measured using a thermocouple, and based on this, an isotherm in the burner cross-sectional direction was created. The results are shown in FIG. Both are measured at the same fuel gas flow rate and air ratio. In Comparative Example 1, combustion is performed inside the cone in front of the burner, and combustion of many fuel gases is completed before reaching the object to be heated. On the other hand, in Example 1, the fuel gas discharged from the main burner is ignited by the flame of the sleeve fire burner in the vicinity of the middle of the burner and the object to be heated, and starts to burn, and a lot of fuel gas is discharged near the object to be heated. Fuel gas is burning. As a result, in the burner of Example 1, since the flame collides with the object to be heated at a high speed and transfers more energy to the surface to be heated, even if the gas temperature in the vicinity of the object to be heated looks almost equal, As shown in FIG. 7, it is considered that a significant improvement in heating power was observed.

DESCRIPTION OF SYMBOLS 1 Burner 10 Burner main body 20 Main burner part 21 Fuel gas nozzle 22 Air nozzle 23 Pressure equalizing chamber 30 Sleeve fire burner part 31 Porous board 33 Space 40 Recess 41 Bottom part 42 Taper part 50 Sleeve fire 60 Flame

Claims

A heating device comprising a burner,
The burner
A main burner section comprising a fuel gas nozzle for discharging fuel gas and an air nozzle for discharging combustion air;
A heating apparatus, comprising: a sleeve fire burner portion that is located outside the main burner portion and burns fuel gas discharged from the main burner portion.
The heating apparatus according to claim 1, wherein the main burner section includes a pressure equalizing chamber on the upstream side of one or both of the fuel gas nozzle and the air nozzle.
The heating apparatus according to claim 1 or 2, wherein the fuel gas nozzle and the air nozzle have a straight pipe structure.
A concave portion having a bottom portion and a tapered portion gradually widening from the bottom portion toward the tip of the burner is provided at the tip of the burner,
The main burner portion is disposed at the bottom;
The heating apparatus according to any one of claims 1 to 3, wherein the sleeve fire burner portion is disposed in the tapered portion.
The heating device according to claim 4, wherein an angle θ formed by the bottom portion and the tapered portion is 20 ° or more.
The heating apparatus according to any one of claims 1 to 5, wherein the sleeve fire burner is a surface combustion burner.
The flaming burner comprises a flaming nozzle selected from a tubular nozzle having a diameter d and a slit nozzle having a width d in the short side direction;
6. The heating device according to claim 4, wherein a tip of the sleeve fire nozzle is provided at a position recessed from d to 15 d from the surface of the tapered portion.
The heating apparatus according to any one of claims 1 to 7, further comprising a flow rate adjusting means capable of independently adjusting a flow rate in the main burner portion and a flow rate in the sleeve fire burner portion.
A heating method of heating using the heating device according to any one of claims 1 to 8.
The heating method according to claim 9, wherein the discharge speeds of the fuel gas and the combustion air discharged from the main burner part are 50 Nm / s or more.
The ratio of the flow rate F1 of the fuel gas discharged from the main burner portion to the flow rate F2 of the fuel gas for the sleeve fire discharged from the sleeve fire burner portion, F1: F2, is set to 70:30 to 85:15. Item 11. The heating method according to Item 9 or 10.