JPH0227309Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to a low NOx multi-burner with excellent heat uniformity.

(Conventional technology) Heating furnaces that require uniform heating include heat treatment furnaces for plated steel plates (such as OGL furnaces) and sintering ignition furnaces, but it is also desirable to uniformly heat steel materials in general heating furnaces. Of course.

By the way, as a conventional method for uniform heating, as adopted in the above-mentioned sintering ignition furnace,
There are methods of installing as many burners as possible and methods of circulating the combustion gas in the furnace using a fan.

And as a burner used in the former method,
Utility Model Application No. 57-145103 is disclosed.

(Problems to be solved by the invention) In the burner of Utility Model Application No. 57-145103, even if the height of the raw material in the pallet or the amount of combustion changes due to fluctuations in operating conditions, the ignition surface on the surface of the raw material becomes hot. The distribution ratio of primary and secondary air is adjusted in order to maintain the appropriate flame length, but when a large number of burners are installed, the temperature directly below the burners is high. Since the temperature of the middle part of each burner is low, in order to raise the temperature of the low-temperature part to a predetermined temperature or higher, a method of increasing the amount of combustion must be adopted.

In order to deal with this problem, the burners disclosed in Japanese Patent Application Laid-open No. 59-89919 and Japanese Patent Application Laid-open No. 59-89920 have been proposed. These burners are designed to ensure uniform heating performance, but since the combustion air is not swirled, when the air and fuel injection speeds decrease, fire stability deteriorates and the range of stable combustion deteriorates. It gets narrower.
Therefore, it must be used under more restricted conditions than conventional burners, and its ability to follow operational fluctuations is insufficient.

On the other hand, the method of circulating the combustion gas in the heating furnace using a fan is a method that can only be used in special cases when the temperature inside the furnace is low, and when the temperature inside the furnace is high, the heat resistance of the fan and shaft may be This is a problem and cannot be used in practice. This method also has the problem of extremely high equipment and operating costs.

(Means for Solving the Problems) The present invention was made in view of the above problems, and has a completely continuous structure in the longitudinal direction with relatively low equipment costs and no increase in operating costs. The present invention aims to provide a multi-burner capable of forming a curtain-like flame and capable of uniform heating.

That is, the present invention is a burner that swirls primary combustion air, and has a front opening surrounded by a burner tile, which has a plurality of fuel injection holes in the longitudinal direction of an oblong crater part, and has a front opening surrounded by a burner tile that has a plurality of fuel injection holes in the longitudinal direction of the horizontally elongated crater part. This multi-burner is equipped with secondary combustion air injection holes on the outer periphery and has inlet pipes communicating with the secondary combustion air injection holes.

(Function) In the multi-burner according to the present invention, the burner vents of the burners arranged adjacent to each other are connected to the combustion air jet holes, so that a continuous curtain-like flame can be formed in the longitudinal direction. This enables general-purpose uniform heating with a wide range of applications.

(Embodiments) The present invention will be described in detail below based on embodiments shown in the accompanying drawings.

Figure 1 shows the first embodiment of the multi-burner according to the present invention. It is placed. and,
The burner tiles 2 of each of these adjacent burners 1 are integrally communicated with each other through their nozzles, and the secondary air jet holes 3 that supply these individual burners 1
Similarly, they are integrated and communicated. Specifically, a plurality of burners that give swirl to the primary air for combustion are arranged adjacently in sequence, and their nozzles are integrally connected to form the flame of each burner in an integral continuous shape. The burner tile is equipped with a burner tile formed by a burner tile, and a secondary air ejection hole is integrally formed in the inner or outer periphery of the crater part of the burner tile, which is opened along the periphery. . In the figure, 4 is a swirl vane, 5 is a primary air introduction pipe, 6 is a secondary air introduction pipe, 7 is a fuel injection pipe, and 8 is a furnace wall. Further, reference numeral 9 denotes a closing member which is provided at the outlet opening of the secondary air jet hole 3 and at an intermediate position between adjacent burners 1, and has the function described below. In other words, the secondary air ejection velocity decreases in the vicinity of the closing member 9, and the amount of backflow circulation of high-temperature combustion gas in the furnace into the flame increases in this area, promoting flame formation and reducing oxygen in the combustion area. This lowers the partial pressure and reduces the production of NOx.

In the case of a multi-burner according to the present invention configured as described above, it is possible to form a continuous curtain-like flame in the longitudinal direction of adjacent burners 1. In addition, in the multi-burner of the present invention, since the interval between the fuel injection pipes 7 can be shortened, it can be suitable for uniform heating. In other words, the multi-burner of the present invention maintains the excellent characteristics of burner 1 related to Utility Model Registration No. 1525694, such as low NOx properties, combustion stability, high turndown properties, and flame length variable performance, while maintaining an unbroken continuous flame length. A curtain-like flame can be formed and uniform heating can be achieved.

In the first embodiment shown in FIG. 1, for example, in order to shorten the flame length, it is sufficient to increase the distribution of primary air that has been given swirl, and conversely, if the distribution of secondary air is increased, the flame length can be shortened. become longer.

Therefore, if only a short flame is required, the first
Secondary air outlet 3 like the first embodiment shown in the figure
It is not necessary to install a burner in particular, and a burner configuration as shown in FIG. 2 is sufficient. In this case, it goes without saying that the closing member 9 is not necessary.

Further, the secondary air jet holes 3 do not necessarily need to be provided on the outer circumference of the burner tile 2 as in the first embodiment, but are provided on the inner circumference of the burner tile 2 as shown in FIG. A secondary air ejection pipe 10 is fitted around the outer circumference of the pipe 5 at a predetermined interval, and the primary air sent through the primary air introduction pipe 5 is
An appropriate number of holes 11 provided at predetermined positions of the secondary air introduction pipe 5
A configuration may also be adopted in which the secondary air is guided to the secondary air jetting pipe 10 via. However, in the third embodiment shown in FIG. 3, although the flame length variable performance is inferior to that of the multi-burner of the first embodiment, there is an advantage that the burner can be made more compact. In this third embodiment, it is optional whether or not to install the closing member 9.

The fourth embodiment shown in Fig. 4 has the burner tile 2 of the first embodiment formed straight, and is used in cases where NOx is extremely increased, such as when oxygen enrichment is performed on combustion air. Suitable for combustion conditions. Further, the fifth embodiment shown in FIG.
The outer periphery of the burner tile 2 in the embodiment is formed to have an enlarged diameter so that secondary air is ejected outward with respect to the burner center axis. A burner with this structure is suitable for a ceiling burner, etc. because the flame spreads outward to form a flat flame due to the ejector effect based on the kinetic energy of the secondary air jet. On the other hand, if the configuration is such that the secondary air is blown out inward with respect to the burner central axis as in the sixth embodiment shown in FIG. Forms a flame suitable for high-temperature, uniform heating. In this case, the velocity of the combustion gas ejected from the burner crater increases, and the ejector effect promotes circulation of the combustion gas within the heating furnace, thereby increasing the effect of equalizing heat in the furnace.

In the seventh embodiment shown in FIG. 7, the burner tiles 2 communicated as described above are formed in a circular shape, and are suitable for, for example, a ceiling burner of a rotary furnace. In addition, if the communicated burner nozzle is made into a closed loop, and the burner nozzle is formed into a ring shape facing inward as shown in Fig. 8, and the flame is directed inward, it is possible to This makes it suitable for heating the end and outer circumferential surface.
On the other hand, as shown in Figure 9, if the burner mouth is formed into a ring shape and the flame is directed outward, it is suitable for heating the inner circumferential surface of the pipe. Become.

The burner shown in Figure 10 uses a heat-resistant material (SUS310S) with excellent thermal conductivity to connect the burner nozzle.
etc.), and is configured so that combustion air passes through the outer periphery of the burner nozzle.In burners with this structure, the inner surface of the burner nozzle is cooled, so the combustion air is enriched with oxygen. Even when the temperature inside the burner crater rises and NOx increases extremely, it is possible to suppress the generation of NOx inside the burner crater. It is possible to prevent coal ash from melting and adhering to the inner surface of the burner tile.

In addition, a burner (Fig. 11) in which a vent continuous with the burner vent is provided on the outside and extension of the air hole ejecting from the outside of the communicated burner vent,
Suitable for localized, high-temperature, uniform heating, and ideal for heating slab edges.

The multi-burner according to the present invention as explained above can be constructed not only in one row but also in a multi-layered structure by making each row inside and outside each other, but in this case, as shown in FIG. If the air ejected from the communicating burner vents is shared between adjacent multi-burner rows, the equipment cost will be low and compact, and it will be suitable for uniform heating over the entire plane.

In addition, if there is no swirl vane 4 of the burner used in the multi-burner of the present invention, the stable combustion range is extremely limited, and the combustible range is, for example, when coke oven gas is used as fuel, the air ratio is 1.1 to 1.5. The turndown is at most 1/2, and in other ranges the flame becomes extremely unstable and may even misfire. On the other hand, when the swirl vanes 4 are installed, the flame not only spreads outward and the flames of adjacent burners coalesce to form a continuous curtain-like flame, but also Mixing with air is promoted, flame temperature is made more uniform, NOx is reduced, and the stable combustion range is significantly expanded. For example, when coke oven gas is used as fuel, the air ratio is 0.4 to 4, and the turndown is 1/20.
The following is possible. However, the turndown is 1/
If it is 8 or less, it is desirable that the primary air ratio is 50% or more.

In addition, a closing member 9 installed in the secondary air outlet 3
It is preferable to install the fuel at the position shown in Figure 1 in order to equalize the flame temperature, but in the case of refractory fuels such as pulverized coal and oil coke, the combustion speed is slow and the flame ignitability is low. In addition to the location shown in FIG. 1, it is also preferable to install the fuel injection pipe near the fuel injection pipe, since this may cause the flame to lift and become unstable. Incidentally, even with a burner having a structure without the closing member 9, the uniformity of flame temperature is much improved compared to the case where a plurality of conventional burners are installed. Needless to say, it is included.

(Experimental Results) A comparison was made between the installation of multiple burners according to Utility Model Registration No. 1525694 and the installation of the multi-burner of the present invention shown in FIG.

For both burners, adjust the fuel valve of each burner at the start of operation, and adjust the primary and secondary air distribution so that the flame comes into proper contact with the raw material surface (from now on, adjust the fuel valve of each burner). , the primary and secondary air valves are fixed), the raw material surface height and combustion amount change due to fluctuations in operating conditions, and the flame contact with the raw material surface is inappropriate (flame length is too long or short). If the temperature becomes too high (too high), the air flow rate control valve installed at the inlet of the primary and secondary air header pipes will
Next, the flame length was adjusted by changing the secondary air distribution.

When the burner is adjusted in this way, the temperature distribution in the sintering ignition furnace (horizontal temperature distribution in the longitudinal direction of the burner at a position 100 mm above the raw material surface) is as follows:
As shown in the figure, it is high right below the burners and low in the middle of each burner. At this time, with a conventional burner (16 burners), the temperature difference was more than 100°C, resulting in an unnecessarily high temperature directly below the burner, but when using the multi-burner of this invention, the number of burners The temperature difference has been increased to more than twice that of the conventional one, and the temperature difference has been reduced to about 1/10 of the conventional one, making it possible to reduce the amount of combustion. Incidentally, in this experiment, the amount of coke gas burned was reduced to 3/4 of the conventional amount, or 25%.

(Effects of the invention) As described above, the present invention has a plurality of burners arranged adjacent to each other, and the burner nozzles of these burners and the combustion air jet holes are communicated with each other, resulting in excellent heat uniformity and combustibility. This has a great effect that can be expected to improve combustion efficiency.

[Brief explanation of the drawing]

1 to 12 are drawings showing an embodiment of the multi-burner according to the present invention, in which FIG. 1A is a front view showing the first embodiment in section, B is a side view, and FIGS.
The figures are front views showing cross-sections of the second to sixth embodiments, and the seventh
The drawings are similar to Fig. 1B of the seventh embodiment, and Fig. 8
9 are explanatory diagrams showing other aspects of the seventh embodiment, FIGS. 10 and 11 are front views showing the eighth and ninth embodiments in cross section, and FIG. 12 is a diagram according to the present invention. FIG. 13, which is a diagram of a multi-burner having a multiple structure, is a drawing comparing the flame temperature distribution between the burner of the present invention and a conventional burner. 1 is a burner, 2 is a burner tile, 3 is a secondary air outlet, and 4 is a swirl vane.

Claims (1)

[Scope of utility model registration request] This is a burner that swirls air for primary combustion, and has a front opening surrounded by burner tiles, and has a plurality of fuel injection holes in the longitudinal direction of the horizontally elongated crater, and a secondary combustion chamber on the inner or outer periphery of the burner tile. A multi-burner comprising a combustion air nozzle and inlet pipes communicating with each secondary combustion air nozzle.