JP3304499B2 - Hot stove iron shell temperature measurement method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inexpensively and accurately measuring the temperature of a hot blast stove.

[0002]

Conventionally, to measure the insulation has been hot-air oven steel shell temperature in order to prevent the furnace shell stress corrosion cracking due to NO _x, it is being performed to monitor the degradation of the insulation cover from that value. Generally, as shown in a cross-sectional view of a part of the hot-blast stove in FIG. 8, the tip of the thermocouple 20 is brought into close contact with the surface of the hot-blast stove 2, and monitoring is performed using the indicated value. FIG. 9 is a perspective view of a positional relationship among a hot stove iron shell, a thermocouple, and a heat insulating cover. That is, in FIG. 8 and FIG. 9, the inner mounting metal frame 4 is provided on the hot blast stove 2 and the stud bolt 11 is attached thereto.
After the heat insulating material 5 and the heat insulating cover 3 are overlapped and applied, they are held down by the outer mounting metal frame 6 and
This is stopped using. Thermocouple 20 is a heat insulating cover
Before installing, place it in place beforehand.
Good.

[0003] By the way, the area of heat retention range is beyond the 1000m ² in per hot-air furnace 1 groups, will be 1000 points be placed one to 1m ^2, it takes a very great deal of costs in the total number installed. Therefore, knowing that it is insufficient, it is a fact that about 50 to 100 thermocouples are installed per hot blast stove when the heat insulating cover is installed.

As means for continuously measuring the temperature in the circumferential direction, a system using an optical fiber and a laser beam has already been disclosed as a known technique. According to this principle, when laser pulse light is irradiated into an optical fiber, various scatterings occur due to fluctuations in the refractive index of molecules in the fiber, and Raman scattering on the anti-Stokes side greatly depends on the temperature of the optical fiber. The temperature at each point where scattered light is generated is determined from the intensity of the scattered light (light returning to the incident end). Further, the distance is obtained from the delay time from the irradiation of the laser pulse light to the return to the incident end as backscattered light.

FIG. 6 shows an example of a system configuration. In this system, laser pulse light can be emitted from either end of a fiber optic cable for temperature measurement. That is, as a first method, the laser pulse light emitted from the laser light source 13 enters the optical fiber cable 1 from the optical switch 16 through the optical coupler 17. Backscattered light generated in the optical fiber is conversely transmitted from the optical coupler 17 through the optical switch 18 to the detector 14.
to go into. As a second method, the laser pulse light enters the optical fiber cable 1 from the optical switch 16 through the optical coupler 19. The backscattered light is conversely
And enters the detector 14 through the optical switch 18. In any case, the weak backscattered light that has entered the detector 14 is amplified and converted into a temperature by the data processing device 15.

As for the application of the present measuring method to the temperature measurement of a steel shell of a blast furnace or the like, as shown in a sectional view of a part of a hot-blast furnace iron shell shown in FIG. 7, an optical fiber cable 1 is fixed to a steel shell by welding. Pressing bolt 22 through metal fitting 21
There is a method of pressing down on the steel bar 23 with.

[0007]

However, in the method using a thermocouple, since the number of thermocouples to be installed is limited, there is a possibility that local deterioration of the heat insulating cover may be overlooked. On the other hand, in the conventional measurement method using an optical fiber, since the fixing metal needs to be firmly welded to the steel shell, the welding heat input is large, so that residual stress remains in the steel shell, which may cause stress corrosion cracking. . The present invention has been made in view of the above-mentioned drawbacks of the prior art, and in adopting a system that uses an optical fiber and laser light for measuring the temperature of a hot stove iron shell, by improving a method of crimping an optical fiber cable that transmits laser light to the iron shell. It is another object of the present invention to provide a method capable of monitoring the deterioration of a heat insulating cover inexpensively and accurately.

[0008]

SUMMARY OF THE INVENTION According to the present invention, an optical fiber cable is provided between a dome, a connecting pipe of a hot stove and a peripheral surface of a shell of a straight body portion and a heat insulating cover by a metal frame for mounting the heat insulating cover. Crimped and wound at an arbitrary interval, connecting both ends of the optical fiber cable to a laser light source and a detector, and measuring the temperature at a point along the optical fiber cable at predetermined intervals based on both ends of the optical fiber cable. It is characterized by.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a part of a hot-blast stove in which an optical fiber cable is installed according to the present invention. FIG. 2 is a perspective view of a positional relationship among a hot-blast stove, an optical fiber cable, and a heat insulating cover. FIG. 3 is a detailed cross-sectional view of a crimping portion of the optical fiber cable to a steel shell.

[0010] In the installation sequence when installing the optical fiber cable in the present invention, the optical fiber cable is temporarily fixed to a hot-blast furnace steel shell before installing the heat insulating cover as shown in FIG.
In the temporary fixing method, the temporary fixing fitting 7 is fixed to the steel shell 2 by welding.
The temporary fixing metal is made of ordinary steel and has good weldability. Since only positioning is required and mounting strength is not required, very simple spot welding is sufficient. In this case, the welding heat input is at most 5,000 J or less, which is 1/10 or less of the heat input of about 50,000 J when the metal fitting is firmly welded to the steel shell, and there is no concern about stress corrosion cracking. Alternatively, the temporary fixing member may be fixed to the iron shell with an adhesive mainly composed of inorganic zirconia having a heat resistance of 300 ° C. or higher.

Next, the optical fiber cable 1 is installed so as to be interposed between the temporary fixing members 7. FIG. 4 is an overall view of a hot blast stove showing an example of a route for installing an optical fiber cable. The optical fiber cable 1 winds the dome 8, the connecting pipe 9, and the straight body 10 of the hot stove in multiple layers. The measurement interval in the longitudinal direction of the optical fiber cable is preferably 1 to 3 m because the distance resolution of the measurement system is 1 m and the measurement interval of the conventional method using a thermocouple is 4 m on average and it is desired to be shorter than this. is there. The interval at which the optical fiber cable is wound is preferably 1 to 3 m in accordance with the measurement interval in the longitudinal direction of the optical fiber cable. However, the dome and the communication pipe, which are liable to undergo stress corrosion cracking, are made dense and the straight body portion is made rough. However, there is no practical problem even if the value deviates slightly.

When the temporary fixing of the optical fiber cable is completed, the inner mounting metal frame 4 serving as the basis for mounting the heat insulating cover is wound around the hot-air stove steel sheath 2 as shown in FIGS. At this time, as shown in FIG. 1, the optical fiber cable 1 is pressed against the hot blast stove 2 by the inner mounting metal frame 4. The stud bolts 11 are welded to the inner mounting metal frame 4 in advance, but the number of optical fiber cables passing through is particularly increased. From above, the heat insulating material 5, the heat insulating cover 3, and the outer mounting metal frame 6 are sequentially mounted, and the nut 12 is fastened and fixed. In addition, the present invention can be applied to the case of a heat insulating cover of an air layer heat insulating type without a heat insulating material.

Next, a specific procedure for measuring the temperature of the iron shell of the hot stove will be described. As an example of the system configuration using the optical fiber and the laser beam for temperature measurement in the present invention, a system shown in FIG. 6 is used. In this figure, there are a plurality of optical fiber cables 1, each of which is installed inside a heat insulating cover of a hot stove, and a laser light source 13 and a detector 14 are installed outside the hot stove heat insulating cover. When an optical fiber is irradiated with a laser pulse light, various scatterings occur due to fluctuations in the refractive index of molecules in the fiber. Among them, Raman scattering on the anti-Stokes side largely depends on the temperature of the optical fiber. The temperature at each point where scattered light is generated can be determined from the intensity of the light that has returned to the end). The distance is obtained from the delay time from when the laser pulse light is irradiated to when the light returns to the incident end again as backscattered light.

The laser pulse light can be emitted from any end of the optical fiber cable for temperature measurement. That is, as the method of the present invention, the laser light source 1
The laser pulse light emitted from the optical switch 16
From the optical fiber cable 1 through the optical coupler 17. Conversely, the backscattered light generated in the optical fiber enters the detector 14 from the optical coupler 17 through the optical switch 18. According to another method of the present invention, the laser pulse light is
The optical switch 16 enters the optical fiber cable 1 through the optical coupler 19. Backscattered light is reversed by optical coupler 1
From 9 enters the detector 14 through the optical switch 18. In any case, the weak backscattered light that has entered the detector 14 is amplified and converted into a temperature by the data processing device 15.

FIG. 5 is an example of continuous measurement of the temperature of the hot-air stove using an optical fiber cable. Here, only a part is displayed. Since the route of the optical fiber cable is determined at the time of the facility, if the distance from the reference point is given, the corresponding steel shell temperature is displayed.

While the present invention has been described with reference to the method of monitoring the temperature of a steel shell for an external combustion type hot stove having a connecting pipe according to the present invention, the method of the present invention is not limited to this. Also, it can be applied to a high-temperature gas generating furnace and the like.

[0017]

The effects of the present invention are listed below. (A) When using a system that uses an optical fiber cable and laser light to measure the temperature of the hot-blast stove iron, the thermocouple is crimped onto the surface of the steel shell inside the heat insulation cover, and the thermocouple is wound on the surface of the steel shell. The number of management points can be increased much more easily than the conventional installation method. (B) When crimping the optical fiber cable to the steel shell, the use of the heat retaining cover mounting metal frame eliminates the need for strong welding of the fixing bracket to the steel shell, and does not adversely affect the steel shell.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a part of a hot-blast stove steel sheath provided with an optical fiber cable according to the present invention.

FIG. 2 is a perspective view of a positional relationship among a hot-blast stove, an optical fiber cable, and a heat insulating cover.

FIG. 3 is a detailed cross-sectional view of a crimping portion of the optical fiber cable to a steel shell

FIG. 4 is an overall view of a hot stove showing an example of an optical fiber cable installation route.

FIG. 5 is a measurement example of a hot blast stove steel bar temperature according to the present invention.

FIG. 6 is a block diagram illustrating an example of a system configuration of an optical fiber.

FIG. 7 is a side sectional view of a conventional installation of an optical fiber cable for measuring the temperature of a steel shell of a blast furnace or the like.

FIG. 8 is a cross-sectional side view of a prior art installation of a thermocouple on a hot-blast stove.

FIG. 9 is a perspective view showing a positional relationship between a hot-blast stove iron skin, a thermocouple, and a heat insulating cover according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical fiber cable 2 Hot-blast stove iron skin 3 Heat insulation cover 4 Inner mounting metal frame 5 Heat insulating material 6 Outer mounting metal frame 7 Temporary fixing metal 8 Dome 9 Communication tube 10 Straight body part 11 Stud bolt 12 Nut 13 Laser light source 14 Detector 15 Data processing device 16 Optical switch 17 Optical coupler 18 Optical switch 19 Optical coupler 20 Thermocouple 21 Fixing bracket 22 Holding bolt 23 Iron shell

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-4-254506 (JP, A) JP-A-4-74813 (JP, A) JP-A-5-332850 (JP, A) JP-A-4- 216425 (JP, A) Japanese Utility Model Hei 6-80142 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01J 5/00 G01J 5/10 C21B 9/10 304 G01K 11/12 G01K 1/14 F27D 21/00

Claims (1)

(57) [Claims] 1. An optical fiber cable is pressure-bonded to the surface of a hot-blast stove with a metal frame for attaching a heat-insulating cover between a dome, a connecting pipe, and a circumferential surface of a steel shell of a straight body portion, and at an arbitrary interval. Wrapping, connecting both ends of the optical fiber cable to a laser light source and a detector, and measuring a temperature at a point along the optical fiber cable at predetermined intervals based on both ends of the optical fiber cable, Temperature measurement method.