JP2774771B2 - Burner and reheating method for refractory lined container - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a burner used for a refractory-lined container and a drying and heating method.

[0002]

2. Description of the Related Art A refractory-lined vessel such as a ladle used for transporting molten steel from a converter to a casting facility has a structure in which a refractory is lined on the inner surface of a pot outer shell made of mild steel or the like. It is. In this type of container, the refractory is damaged or melted by thermal shock at the time of tapping in the converter or by continuous contact with molten steel, so that the refractory must be repaired periodically.

[0003] In performing this repair, skill is required to use a fixed refractory having a predetermined shape such as a block shape from the beginning, and the work requires heavy labor. There is a tendency to repair using irregular-shaped refractories in the shape of mud or mud, etc., thereby trying to rationalize the work. By the way, the irregular shaped refractory differs from the regular shaped refractory when it is not dried (at the time of repair work) and contains 6 to 7% of water. For this reason, if rapid drying is performed as in the case of fixed refractories, there is a risk of explosion, and gradual drying and heating is required.

Therefore, conventionally, a burner (also used for heating when the container is used) is provided so that the crater is directed from the center of the upper opening of the container to the bottom, and the burner is operated with a low load during the drying period of the refractory. Along with the combustion flame from the periphery of the crater along with the combustion flame, secondary air with a higher flow rate than the primary air is jetted out while the combustion state is squeezed, so as to lengthen the combustion flame, This causes the combustion gas to circulate in a vertical direction, so that the upper region and the lower region in the container are gradually heated while maintaining a uniform temperature.

[0005]

The combustion gas accelerated by the secondary air collides with and reflects at the center of the bottom of the container, thereby causing a vertical circulating flow. for that reason,
The central portion of the bottom was heated more intensively than other portions, and a temperature difference of as much as 200 ° C. was actually generated between the central portion and the peripheral wall.

There was no problem if the bottom of the container was made of a fixed refractory (when the fixed refractory was also used for repair), but recently, the repair work has been further streamlined. In addition, it has been considered to use an amorphous refractory also at the bottom. Therefore, if drying is performed in accordance with the heating of the refractory on the peripheral wall in the conventional heating method, it is inevitable that the refractory at the bottom, particularly at the center, will explode. In order to prevent this, it is necessary to weaken the jet flow of the secondary air, but this causes the combustion flame to be insufficiently long, resulting in a long drying time and excessive fuel consumption. There was a point. In addition, the refractory disposed at the bottom of the bottom and the surrounding wall, etc., does not remove moisture sufficiently,
There was also a problem of insufficiency of strength. In addition, the secondary air requires a flow rate adjustment while checking the refractory temperature of each part, so that there is a problem that it is difficult and time-consuming.

The present invention has been made in view of the above circumstances, and causes explosion of a refractory or lack of strength not only in a container or the like using an irregular refractory not only on the peripheral wall but also on the bottom. It is an object of the present invention to provide a burner and a drying and heating method used for a refractory-lined container, which can quickly and easily dry a refractory material and can reduce the cost.

[0008]

According to the present invention, the following technical measures have been taken in order to achieve the above object. That is, in the present invention relating to a burner, in a burner used for a refractory-lined container having at least two secondary air outlets provided around the periphery of the crater, the crater is provided toward the center of the bottom of the container. In such a state, the secondary air outlet is provided so as to be inclined outward toward the bottom peripheral portion of the container.

[0009] The axis inclination angle θ of the secondary air outlet with respect to the burner axis of the crater portion is expressed as follows: 1/2 (0.3D-d) / L ≦ tan θ ≦ 1/2 (0.
85D-d) / L where D is the bottom diameter of the container, d is the diameter of the pitch circle of the secondary air outlet, and L is the depth of the container.

[0010] It is also possible to use a wide-angle nozzle for the secondary air outlet. On the other hand, in the present invention according to the drying / heating method for heating the refractory-lined container, the combustion flame is sprayed toward the center of the bottom of the container, and the combustion flame is directed outward toward the bottom periphery of the container at the periphery of the combustion flame. The secondary air jet is inclined at an angle of at least until the refractory provided on the upper and lower areas of the peripheral wall and the bottom of the container has passed the dry season at least until the refractory has passed the dry season. It is characterized by not exceeding.

[0011] In a drying and heating method for heating a refractory-lined container using a burner having at least two secondary air injection ports provided in a periphery of a crater, a secondary air with respect to a burner axis of the crater is provided. The axial inclination angle θ of the ejection port is set to （(0.3D−d) / L ≦ tan θ ≦ 1/2 (0.
85D-d) / L where D is the diameter of the bottom of the container, d is the diameter of the pitch circle of the secondary air outlet, and L is the depth of the container. During the heating period, the amount of primary air supplied to the crater is kept constant, and the amount of secondary air supplied to the secondary air outlet is controlled to a predetermined ratio in relation to the fuel flow rate.

[0012]

In the burner according to the present invention, the secondary air outlet is inclined outward so as not to follow the combustion flame from the crater but to the peripheral portion of the bottom of the container. Therefore, the agitated flow that occurs in the vessel is not concentrated at the bottom center,
There is no large temperature difference between the center of the bottom and other parts.

In particular, if a wide-angle nozzle is used as the secondary air jet, the combustion gas can be dispersed and collided with the secondary air over a wide range from the peripheral wall to the bottom. If the maximum width of the temperature difference generated in the container (particularly, the temperature difference between the center of the bottom and the other part (for example, the upper region of the peripheral wall)) is kept within 50 ° C., a reasonable heating can be achieved. This is preferable from the viewpoints of thermal conductivity, fuel consumption rate and the like.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side sectional view schematically showing a burner 1 according to the present invention, in which a fuel guide tube 3 is provided around a flame holding tube 2 serving as a core, and a fuel injection tube is provided at a downwardly leading end thereof. A port 4 is formed. A primary air guide tube 5 is provided around the fuel guide tube 3 so as to be fitted around the fuel guide tube 3.
Is formed. Reference numeral 7 denotes an annular spacer having ventilation holes (not shown) at predetermined intervals in the circumferential direction.

The primary air supply cylinder 5 extends below the fuel injection port 4 so that a crater 8 is formed inside the extension. That is, COG
(A coke oven gas) or the like and a fuel gas G injected from a gas supply source (not shown) to the fuel injection port 4 through the fuel supply tube 3
And primary air A1 injected from a primary air source (not shown) such as a blower, a fan, or a blower to a primary air jet port 6 through a primary air guide cylinder 5, and is appropriately stirred in the crater portion 8. The stable combustion flame 10 is obtained by mixing.

A secondary air guide path 14 is provided around the primary air guide cylinder 5. This secondary air guideway 1
A plurality of secondary air outlets 15 are provided in the 4 at regular intervals so as to surround the periphery of the crater 8. And these secondary air jets 15
Each is inclined outward. FIG. 2 is a side sectional view showing a situation in which the burner 1 is provided at an upper opening portion of a refractory-lined container 20. Department. Reference numeral 22 denotes an irregular refractory provided on the peripheral wall 23, and reference numeral 24 denotes an irregular refractory provided on the bottom 21. Reference numeral 25 denotes a lid of the container 20.

In such a state, the secondary air outlet 15 (see FIG. 1) is directed to the peripheral portion of the bottom 21. Secondary air A2 from a secondary air source (not shown), which has a unique configuration or also serves as the primary air source described above, is supplied to each secondary air ejection port 15.
Is supplied via Therefore, the combustion gas of the combustion flame 10 that stably burns at the crater portion 8 is supplied to the plurality of secondary air outlets 1.
5 is entrained in a secondary air jet 16 ejected outward from the container 5 and is diffused. The particles are dispersed and collide with a wide area extending from the part to the peripheral part to cause a stirring state. Therefore, there is no localized / intensive heating portion.

Assuming that the diameter of the bottom 21 of the container 20 is D, the depth is L, and the pitch diameter of the secondary air outlet 15 is d (see FIG. 1), The angle θ at which the secondary air outlet 15 is inclined is （(0.3D−d) / L ≦ tan θ ≦ 1/2 (0.
85D-d) / L.

FIG. 3 shows the inclination angle θ of the secondary air outlet 15.
Was varied and the combustion experiment was performed.
This is the result of examining the temperature distribution at the time when the temperature exceeds 0 ° C., where the horizontal axis indicates the radial position (9 places) of the bottom 21, the side indicated by “0” is the center, and “1.0” is the center. "Means that the peripheral wall 23 is provided. The vertical axis is the bottom 2
1 (refractory 24). Is tan θ = 1
/ 2 (0 / 4D-d) / L, tan θ =
In the case of 1/2 (1 / 4D-d) / L, tan θ
= Tan (2 / 4D-d) / L, tan
The case where θ = １ ／ (3 / 4D−d) / L is shown.

FIG. 4 shows the temperature difference between the maximum temperature and the minimum temperature in the above. These figures 3
4 and FIG. 4, it is clear that the inclination angle θ of the secondary air outlet 15 greatly affects the inner surface temperature distribution of the bottom 21 (the refractory 24). And according to the result, t
While the anθ deviates from the predetermined range and the temperature difference between the minimum temperature and the maximum temperature exceeds 50 ° C.,
When tan θ falls within the predetermined range, the difference between the minimum temperature and the maximum temperature is within 50 ° C., that is, the temperature distribution is substantially uniform. It has been found that the critical value of x to be tan θ at this time is 0.3 to 0.85.

As shown in FIG. 5, if the secondary air outlet 15 is a wide-angle nozzle whose inner diameter increases toward the tip of the opening, the secondary air jet flow 16 can be expanded, and The effect of temperature uniformity was obtained. FIG. 6 shows the results of a drying heat-up test using a specific burner 1 according to the embodiment of the present invention. The container 20 used had a capacity capable of transporting about 250 t of molten steel, and the entire surface of the bottom 21 was made of an amorphous refractory 24. In the burner 1, the secondary air outlet 15 sets the inclination angle θ with respect to the burner axis P to tan θ = １ ／ (0.5D−d) /
L and a wide-angle nozzle type having a divergence angle α of 21 ° as shown in FIG. The temperature measurement points are all 9 in the radial direction of the bottom 21.
Point (Temperature sensor was installed on the inner surface side of refractory 24)
And the method of picking up the highest temperature portion and the lowest temperature portion in those temperature distributions.

As a result, it was confirmed that at least up to the point in time after the drying period of the refractory 24 (about 30 hours), the temperature was kept at a maximum of 40.degree. FIG. 7 shows a control state of the secondary air supply amount at the time of heating. If the secondary air ratio is increased with a decrease in the fuel flow rate, the lower region temperature in the container 20 can be higher than the upper region temperature. On the contrary, if the secondary air ratio is decreased with an increase in the fuel flow rate, a short path can be caused to increase the temperature in the upper region of the container 20 from the temperature in the lower region. In the present invention, since the secondary air ratio with respect to the fuel flow rate can be increased as a whole as compared with the conventional case, it is possible to effectively generate the stirring action. Of course, it is possible to achieve quickness of heating temperature increase, suppression of fuel consumption, improvement of thermal efficiency, and the like.

[0023]

According to the present invention, the secondary air outlet is inclined outward so as to be directed to the peripheral portion of the bottom of the container. From the upper region or lower region of the peripheral wall to the central portion of the bottom or the peripheral portion of the bottom wall, a wide area is dispersed and collided to cause a stirring state. Therefore, there is no localized or intensive heating portion, and explosion of the refractory can be prevented. Of course, there is no possibility of insufficient strength of the refractory due to insufficient water removal. In particular, if a wide-angle nozzle is used as the secondary air ejection port, those effects become more remarkable.

When the maximum width of the temperature difference generated in the container is kept within 50 ° C., it is possible to increase the heat without difficulty, and to improve the heat conductivity, the fuel consumption rate, etc. efficiently. Speeding up and cost reduction. Then, after providing the secondary air ejection port as described above, the primary air supply amount to the crater portion is fixed, and the secondary air supply amount to the secondary air ejection port is determined in relation to the fuel flow rate. If the ratio is controlled, there is an advantage that not only ease of control and uniformity of the temperature in the container can be achieved, but also rapidity of heating temperature increase, suppression of fuel consumption, improvement of thermal efficiency, and the like can be achieved.

In addition, since the drying and heating can be performed quickly, many containers (particularly, in the case of a ladle or the like) can be processed with a small number of heating devices (burners), so that the equipment can be reduced in size and equipment investment can be simplified. .

[Brief description of the drawings]

FIG. 1 is a side sectional view schematically showing a burner according to the present invention.

FIG. 2 is a schematic side cross-sectional view showing a situation where a burner is attached to a container.

FIG. 3 is a line graph showing the results of a combustion experiment performed by changing the inclination angle of the secondary air outlet.

FIG. 4 is a line graph showing a temperature difference in the combustion experiment of FIG.

FIG. 5 is an enlarged sectional view when a secondary air injection port is a wide-angle nozzle.

FIG. 6 is a line graph showing a result of performing a drying heat-up test using a specific burner according to an embodiment of the present invention.

FIG. 7 is a graph showing a control state of a secondary air supply amount during heating.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Burner 8 Crater 10 Combustion flame 15 Secondary air jet 16 Secondary air jet 20 Container 21 Bottom 23 Perimeter wall 24 Refractory

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-59-145405 (JP, A) JP-A-6-1222059 (JP, U) JP-B-55-39431 (JP, B2) JP-B-58- 28487 (JP, B2) Japanese Patent Publication No. 1-13009 (JP, B2) Jikken Sho 63-3737 (JP, Y2) Jikgyo 1-25870 (JP, Y2) (58) Fields surveyed (Int. Cl. ⁶ , DB name) F23D 14/22 B22D 11/10 310 B22D 41/015 F27D 1/16 F26B 23/02

Claims (5)

(57) [Claims] 1. A burner for use in a refractory-lined container (20) having at least two secondary air outlets (15) provided around the crater (8), wherein the crater (8) is a container. The secondary air outlet (15) is provided so as to be inclined outward toward the periphery of the bottom (21) of the container (20) in a state where the secondary air outlet (15) is provided toward the center of the bottom (21) of (20). A burner for a refractory-lined container, characterized in that the burner is used. 2. The inclination angle θ of the secondary air outlet (15) with respect to the burner axis (P) of the crater (8) is: 1/2 (0.3D−d) / L ≦ tan θ ≦ 1 / 2 (0.
85D-d) / L where D is the diameter of the bottom (21) of the container (20), d is the pitch circle diameter of the secondary air jet (15), and L is the depth of the container (20). The burner used for a refractory-lined container according to claim 1, wherein: 3. The burner used for a refractory-lined container according to claim 1, wherein a wide-angle nozzle is used for the secondary air outlet (15). 4. A drying and heating method for heating a refractory-lined container (20), wherein a combustion flame (10) is sprayed toward a center of a bottom (21) of the container (20), and the combustion flame (10) is sprayed. A secondary air jet (16) inclined outwardly toward the bottom (21) of the container (20) is jetted around the periphery of the container (20), and the upper region of the peripheral wall (23) in the container (20) and The refractory lining is characterized in that the temperature difference between the parts does not exceed 50 ° C. at least until the refractory (22, 24) provided in the lower region and the bottom (21) has passed the drying period. Drying and heating method of the container. 5. A drying and heating method for heating a refractory-lined container (20) using a burner having at least two secondary air outlets (15) provided around a crater (8), The axial inclination angle θ of the secondary air outlet (15) with respect to the burner axis (P) of the crater portion (8) is expressed as follows: 1/2 (0.3D−d) / L ≦ tan θ ≦ 1/2 (0.
85D-d) / L where D is the diameter of the bottom (21) of the container (20), d is the pitch circle diameter of the secondary air jet (15), and L is the depth of the container (20). The primary air supply to the crater (8) is kept constant throughout the drying period of the refractory (22, 24) and the heating period of the container (20), and the secondary air outlet (15) is supplied to the secondary air outlet (15). A method for drying and heating a refractory-lined container, wherein a secondary air supply amount is controlled to a predetermined ratio in relation to a fuel flow rate.