JP5058682B2 - Coke oven crack hot repair method - Google Patents

Description

  The present invention relates to a technique for hot repairing a crack generated in a refractory brick furnace wall separating a carbonization chamber and a combustion chamber of a coke oven.

  The coke oven is divided into a combustion chamber for heating the furnace and a carbonization chamber for generating coke, and refractory bricks such as quartz brick are used for the wall surface. Over many years of use of the furnace, the refractory brick furnace wall has surface defects and cracks. In particular, when cracks in the furnace wall progress, there is a problem that the strength of the furnace wall is lowered and the life of the furnace body is remarkably shortened. Moreover, if the crack penetrates from the carbonization chamber to the combustion chamber, coke gas flows from the carbonization chamber into the combustion chamber, causing incomplete combustion and causing black smoke. Therefore, it is essential to detect cracks at an early stage and repair them for long life and stable operation of coke ovens.

  The easiest way to repair the furnace wall is to stop and cool the furnace. However, silica bricks used for the main structure of a coke oven have high mechanical strength at high temperatures, but large expansion and contraction during heating and cooling. For this reason, when the furnace temperature is lowered, the bricks are cracked greatly and there is a high risk of damaging the entire furnace wall. Therefore, in order to avoid such a danger, it is necessary to repair the furnace wall in the vicinity of 1000 ° C. operating temperature.

  Among the damages to the furnace wall, as a method for repairing the concave portion due to surface defects, for example, as disclosed in Patent Documents 1 and 2, it is possible to use a repair method in which a powder refractory is sprayed with a burner. In this case, hot repair can be performed by protecting a repair device such as a furnace wall observation device or a thermal spray burner with a water cooling jacket.

  In the case of crack damage, the narrow crack width on the furnace wall surface is 10 mm or less. On the other hand, in the repair method by thermal spraying, since the refractory of the powder refractory sprayed from the burner is relatively large, the spraying range is at least 10 mm or more. As a result, when the crack is repaired by the thermal spray burner, the thermal spray filling portion 5 rises from the surface as shown in FIG. The convex part of the furnace wall on the side of the carbonization chamber increases the resistance when extruding coke and, as a result, increases the extrusion pressure from the carbonization chamber to the combustion chamber side, increasing the load on the furnace wall and increasing the life of the furnace body. It causes a significant decrease. Further, since the thermal spray powder hardly penetrates into a narrow crack, there is a problem that the amount of powder filling the crack is small and the repair strength cannot be obtained sufficiently.

  As another crack repairing method, a dry seal method in which a powdered or liquid refractory is blown from the carbonization chamber side while the internal pressure of the carbonization chamber is increased with respect to the combustion chamber and deposited in the crack is disclosed in Patent Document 3. Etc. are disclosed. However, with this method, the refractory is only deposited in the cracks, so that it is not possible to obtain strong adhesion as in the thermal spraying method, and therefore it is difficult to maintain the strength as the furnace wall. In addition, repairing cracks with a relatively large crack width requires time to deposit the powder. In particular, cracks that crack linearly from the carbonization chamber to the combustion chamber easily pass through the powder. Was impossible.

  That is, in the conventional technique, when repairing cracks in the furnace wall hot, reliable and high-strength repair is impossible without affecting the life of the furnace wall.

Japanese Patent Laid-Open No. 2000-212566 JP 2004-277527 A JP 2004-231681 A

  An object of the present invention is to provide a method for repairing a crack that can reliably obtain repair strength without deteriorating the life of the furnace body in a method for hot repairing a crack generated in a furnace wall refractory brick of a coke oven. There is. Another object is to smooth the surface after repair, reduce the coke extrusion load, and extend the life of the furnace body.

  The present invention is a hot repair method for a coke oven that hotly repairs a crack generated in a refractory brick furnace wall that separates a carbonization chamber and a combustion chamber of a coke oven, and the step of detecting the crack position; A coke oven comprising: a step of irradiating the crack portion and the periphery thereof with laser light along the crack to melt and resolidify the refractory brick around the crack portion to close the crack portion This is a hot repair method.

  Further, the present invention is a hot repair method of a coke oven crack for hot repairing a crack generated in a refractory brick furnace wall separating a carbonization chamber and a combustion chamber of a coke oven, and detects the crack position. A step of irradiating a laser beam along the crack to melt the refractory brick, spraying a high-pressure gas to remove the melted refractory brick and forming a groove, and forming a powder along the groove A method for hot repairing a coke oven, comprising spraying a body refractory and filling a groove and a crack.

  Further, the present invention is the step of melting the refractory brick by the laser irradiation, and injecting the high-pressure gas to remove the molten refractory brick to form the groove portion, the temperature of the high-pressure gas is 300 ° C. or more and 1000 ° C. A hot repair method for a coke oven characterized by the following.

Further, the present invention, when the width of the groove formed by the laser irradiation Wg, the depth dg, refractory bricks thickness was t _o, Wg is not less 10mm or more, the groove forming portion refractory bricks remaining thickness t = T ₀ -dg is a hot repair method for coke oven cracks, characterized in that it is 30 mm or more.

  Further, the present invention is characterized in that the refractory brick is a silica brick having a SiO2 content of 93% by weight or more, and at least one of the refractory brick temperature or the furnace atmosphere temperature is 300 ° C. or higher and 1800 ° C. or lower. This is a hot repair method for coke ovens.

  According to the first method of the present invention, the cracked portion is closed by the melted / re-solidified material of the refractory brick generated by the laser irradiation, the convex portion of the furnace wall surface is not generated, and the crack is sufficiently deep by the deep melting. Can be closed. Further, in the second method of the present invention, a groove having a width of, for example, 10 mm or more is formed by laser irradiation, and a powder refractory is subsequently spray-filled by a thermal spray burner. Reliable repair is possible. In addition, since the depth of the groove formed by the laser is 30 mm or more, it is possible to maintain the mechanical strength of the brick when forming the groove, and it is safe without affecting the strength of the furnace wall. Can be repaired. With these inventions, it is possible to reliably repair cracks in the coke oven without deteriorating the life of the furnace body.

  Since a laser is used as the processing means, the laser beam is guided to any position in the furnace between the heat through a transmission optical device composed of an optical fiber or a reflection mirror, which is protected by a heat insulating and cooling jacket. Suitable for hot repair because it is possible. In addition, the laser has high beam directivity and power controllability, and it is possible to form a melted / resolidified layer or groove with a desired width and depth with high precision, limited to the periphery of the crack. Also have.

  FIG. 8 is a schematic diagram of a crack generated in the furnace wall and the furnace wall. The furnace wall 2 is made by stacking refractory bricks, and each refractory brick has a width of 300 to 400 mm, a height of about 100 mm, and a thickness of 100 to 150 mm. The crack 1 is often generated starting from a joint that is a joint between bricks, and has a shape that is long in the vertical direction of the furnace wall 2. Further, the crack 1 often penetrates from the carbonization chamber in the width direction of the combustion chamber.

  The main structure of the coke oven wall 2 is made of silica brick (SiO2 content 93 wt% or more, thermal expansion coefficient 1.25% or less at 1000 ° C.) having a small coefficient of thermal expansion in a high temperature range of 1000 ° C. or more. This is because silica bricks have high mechanical strength at high temperatures and are excellent in structural properties. However, as shown in FIG. 9, silica brick has a large volume expansion coefficient with respect to temperature change and relatively low toughness as compared with other clay bricks, and therefore, cracks are likely to occur with respect to rapid temperature change. Therefore, cooling the silica brick once once stabilized in the operating temperature range of the coke oven is highly likely to cause fatal damage to the structure of the furnace wall 2. Further, if the crack 1 is repaired by thermal processing such as thermal spraying at room temperature after cooling, there is a problem that the refractory brick breaks because a local temperature deviation occurs.

  On the other hand, silica brick has a feature that the volume expansion coefficient decreases in a temperature range exceeding 300 ° C., and there is almost no volume change particularly in a region exceeding 700 ° C. Therefore, the present inventors do not cause damage even in low-toughness silica bricks in the high temperature range, and if thermal processing using a laser, repair processing of cracked parts that require high position controllability The present invention has been obtained based on the idea that the present invention can also be applied.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 5 is an explanatory diagram of an apparatus according to the present invention. This apparatus includes a CCD camera 7 and a laser output head 8 for detecting cracks, a laser beam reflecting mirror 10, a condensing lens 11, a water-cooling jacket 16 containing them, a laser processing head 15, and a second of the present invention. It consists of a thermal spray flame burner 19 and a high pressure gas nozzle 18 used in the method. The apparatus protected by the water cooling jacket 16 can be moved to any location in the coke oven carbonization chamber by a robot arm (not shown).

  FIG. 1 is an explanatory diagram of the first method of the present invention. This method is performed using the apparatus shown in FIG. 5, and the step (A) of detecting the location of the crack 1 generated in the furnace wall 2 with the CCD camera 7 and collecting and accumulating the positional information of the crack 1; It comprises a step (B) of irradiating a laser beam 6 along the crack 1 based on the detected position information to form a refractory brick melting / resolidifying part 3 and closing the crack 1.

  In the method of the present invention, first, an image of the furnace wall 2 on the coking chamber side is taken by the CCD camera 7 to search and detect the crack position. Since the temperature inside the coke oven is 1000 ° C., heat radiation noise from the furnace wall 2 is generated, and in order to remove this noise, a clear image can be obtained by using the filter 12 shown in FIG. 5 that blocks red light. it can. The captured image signal and the robot arm position coordinate data are synchronized, and crack position data is collected and stored in a data storage device (not shown).

  Next, after moving the laser processing head 15 to the crack position by operating the robot arm based on the crack position data, the laser beam is scanned and irradiated along the crack 1 at an appropriate speed. Here, the laser light is transmitted through the optical fiber 9 from a laser device (not shown) installed outside the coke oven, and is output from the laser output head 8. The laser beam 6 is condensed via the reflection mirror 10 and the condenser lens 11. The focused beam is irradiated into the furnace through the laser passing nozzle 17 at the tip of the laser processing head 15 to process the crack 1. Here, the inside of the water cooling jacket 16 is pressurized by the cooling air 13, and the air used for cooling is discharged from the nozzle 17. The cooling air 13 has an effect of preventing the inflow of dust from the nozzle opening and protecting the optical component. The laser processing head 15 has a double rod nozzle structure, and is provided with a high-pressure gas nozzle 18 coaxially with the nozzle 17. It is possible to inject the processing assist gas 14 heated from 300 ° C. to 1000 ° C. through the nozzle 18 from a high temperature / high pressure gas supply device (not shown) to the processing portion.

  FIG. 2 is a schematic view when a crack is closed by the first method of the present invention. The first method is applied, for example, when the crack width is small. Both the refractory brick furnace walls 2 of FIGS. 2 (A) and 2 (B) are cross-sectional views. FIG. 2A shows a state in which the crack 1 is irradiated with the laser beam 6. The refractory brick instantaneously reaches 1700-1800 ° C., the melting point, and melts by laser irradiation. FIG. 2 (B) shows a state in which the melted / resolidified part 3 is generated in the refractory brick after the laser irradiation. The melting depth dm varies depending on the condensing power density of the laser beam and the scanning speed, and can be 100 mm or more corresponding to the penetration at the maximum. The melt width Wm can be controlled by the irradiation beam, power density and scanning speed. In the method of the present invention, a molten layer is formed by irradiating the upright wall surface with a laser from the lateral direction. Therefore, the melting part is parallel and horizontal to the floor surface. For this reason, coupled with the relatively high viscosity of the molten brick, there is almost no molten component flowing out from the molten portion, and the molten brick remains at the processing position. As a result, the melted / resolidified portion 3 is formed to fill the crack 1 after the laser beam passes, and the crack 1 is closed.

  The laser irradiated portion locally has a temperature of 1800 ° C. or higher corresponding to the melting point, and a temperature difference of 800 ° C. or higher is generated from the non-irradiated portion. However, as estimated from FIG. 9, since there is almost no volume change in the high temperature range, cracks around the processed part due to temperature deviation do not occur. Further, the swell of the melting / resolidifying part 3 hardly occurs. This is thought to be due to the fact that part of the molten brick evaporates during processing and a slight volume shrinkage during solidification. Therefore, since no convex portion is generated on the surface of the furnace wall repairing portion, there is no increase in resistance pressure during coke extrusion, and there is no influence on the life of the furnace body.

  FIG. 3 is an explanatory diagram of the second method of the present invention. This method detects the location of the crack 1 generated in the furnace wall 2 and collects and accumulates the positional information of the crack 1 (A), and the laser beam 6 along the crack 1 based on the detected positional information. Irradiating and removing the refractory bricks around the cracked portion to form the groove 4 and spraying the powder refractory 20 with the spray flame burner 19 along the groove, crack 1 and groove And a step (C) of forming a crack filling portion 5 for filling 4.

  The detection process of the crack 1 is the same as the first method of the present invention. Next, laser irradiation is performed based on the detected crack position data. Here, simultaneously with melting of the refractory bricks by laser irradiation, the molten refractory bricks are removed by injecting the high-pressure gas 14. At this time, even if the high-pressure gas is normal temperature, the processing gas instantaneously becomes the atmospheric temperature in the furnace due to the heat generated in the laser irradiation unit and the atmospheric temperature in the furnace. However, when it is desired to increase the removal rate of the melt, it is necessary to inject a large amount of gas. In this case, the refractory bricks may be partially cooled and cracks may occur. In that case, it is desirable to heat the high-pressure gas 14 in advance and inject it as a high-temperature gas. The gas temperature at that time is preferably 300 ° C. or higher, which is the volume stable temperature range of the silica brick, and 1000 ° C. or lower, which is the furnace atmosphere temperature.

  Next, based on the crack position data, the thermal spray powder burner 19 is used to spray the refractory powder 20 along the crack 1 after the formation of the groove portion 4, and form the spray filling portion 5 to close the crack 1. Let

FIG. 4 is a schematic view when the crack 1 is closed by the second method of the present invention. The second method is applied, for example, when the crack width is large. All of the refractory brick furnace walls 2 of FIGS. 4A, 4B, and 4C are cross-sectional views. FIG. 4A shows a state in which the laser beam 6 is irradiated to the crack 1. FIG. 4B shows a state in which the groove 4 is formed around the crack after the groove is processed by laser irradiation. The width Wg of the groove 4 to be formed is preferably 10 mm or more. This is because the thermal spraying method using a flame burner used in the subsequent process spreads the resistant fine powder, and there is a limit to the thermal spraying accuracy of the powder. For narrow grooves with a groove width of less than 10 mm, the flatness of the sprayed part is reduced. This is because it is difficult to maintain and uniformly fill the inside of the groove. On the other hand, since the thermal spray burner is a technique suitable for filling a wide area groove portion, the maximum value of the groove width is not particularly specified. However, if the groove width exceeds 100 mm, the time and load for laser grooving will increase, and the strength of the furnace wall during groove formation will also decrease, so the groove width is preferably up to about 100 mm. Further, as for the groove depth, when the remaining thickness t of the refractory brick is less than 30 mm, the strength of the refractory brick is remarkably reduced, a partial puncture is generated, and further, there is a possibility of being cramped. Accordingly, as the depth shape of the groove portion 4, the relationship between the remaining refractory brick thickness t after the groove formation, the depth dg of the groove portion 4 and the refractory brick thickness t ₀ before the groove formation is t = t ₀ −dg. , T is preferably limited to the depth dg of the groove 4 where it is 30 mm or more. The depth of the groove 4 can be controlled by adjusting the laser power density, the scanning speed, and the like.

  After the groove is formed, the thermal spray filling portion 5 of the refractory powder is formed by the thermal spray flame burner 19 as shown in FIG. By forming the wide groove, it is possible to form the flat spray filling portion 5 by the spray flame burner 19, and therefore, there is no increase in coke extrusion pressure and no influence on the furnace body life. Moreover, since the crack part periphery is removed widely and repaired compared with the 1st method of this invention, it has the advantage that stronger repair is possible.

Example 1
1 shows an embodiment of the first method of the present invention. In this example, hot repair at 1000 ° C. was performed using a test furnace, the state of the repair was observed with a CCD camera, and then cooled and analyzed for a processing cross section and the like.

  A fiber laser having an average output of 2 kW was used as the laser device. Since the fiber laser itself is a laser oscillation medium, the fiber laser has the advantage that the coupling efficiency to the optical fiber is high and the oscillation efficiency is high, so that the apparatus is compact and the apparatus can be easily installed near the coke oven.

  Using the apparatus shown in FIG. 5, the method of the present invention was carried out at an in-furnace temperature of 1000 ° C. of the silica brick furnace wall. The crack is detected by the CCD camera 7, and the crack width is 0.5 to 1 mm. After the laser beam 6 was collected by a lens, it was applied to a refractory brick. The focal length of the condensing lens 11 is 200 mm, and the condensing beam diameter is about φ0.2 mm. The high temperature / high pressure processing assist gas 14 is not used. The laser beam was scanned at a speed of 3 mm / s. In the hot observation of the processed part with the CCD camera 7, it was confirmed that the cracks were closed and that no cracks or the like occurred in the peripheral part. Further, after the test furnace was cooled, the processed cross section was analyzed. As a result, a melted / resolidified portion was formed with an average depth of about 30 mm and a width of 3 mm, and the cracks in the portion were closed. In addition, it was confirmed that the unevenness from the normal brick surface of the melted / resolidified part had no convex part, the concave part had a maximum depth of 3 mm or less, and the crack was repaired with a substantially flat surface.

Example 2
2 shows an embodiment of the second method of the present invention. This example was also carried out in the same test furnace as in Example 1, using the apparatus shown in FIG. The crack width is 1 mm to 10 mm. The condensing diameter of the laser beam was 16 mm, and the scanning speed was 0.5 mm / s. At the same time, high-temperature compressed air of about 700 ° C. was injected as high-temperature high-pressure gas 14 from the nozzle 18 at high pressure. As a result, the melted refractory brick in the laser irradiation part was removed by high-pressure gas, and a groove having a width of 15 mm and a depth of about 5 mm was formed by one scan. By repeating this scanning five times, a groove having the same width and a depth of about 20 mm was formed.

  Next, as shown in FIG. 6, the powder refractory 20 was sprayed with a thermal spray flame burner 19 to perform filling repair of the groove. Hot cracks confirmed that the cracks were filled. Next, analysis of the cross-section of the repaired part after cooling confirmed that the cracks were closed and that good cracks were repaired.

  The present invention is most effective in the crack repairing method performed between 1000 ° C. and hot for the silica brick used for the furnace wall of the coke oven, but also in other refractory bricks having different thermal expansion coefficients. By selecting an appropriate temperature range, refractory bricks can be repaired without affecting the furnace body.

  In the above embodiment, the crack width is confirmed by the CCD camera 7, and if the crack width is smaller than a preset value based on the result, the first method is used and the crack width is used. If the value is larger than the set value, the second method may be used.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such examples. It will be apparent to those skilled in the art that various changes or modifications can be made within the scope of the ideas described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs.

It is explanatory drawing of the process in the 1st method of this invention. It is explanatory drawing of the crack repair part in the 1st method of this invention. It is explanatory drawing of the process in the 2nd method of this invention. It is explanatory drawing of the crack repair part in the 2nd method of this invention. It is explanatory drawing of the apparatus in connection with the 1st method of this invention. It is explanatory drawing of the groove | channel filling process by the thermal spray flame burner in the 2nd method of this invention. It is explanatory drawing of the crack repair part by the conventional method. It is explanatory drawing of the furnace wall and crack of a coke oven. It is explanatory drawing of the temperature dependence of the thermal expansion of a brick.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Crack 2 Refractory brick furnace wall 3 Melting and re-solidification part 4 of a refractory brick 5 Groove part formed around a crack 5 Thermal spray filling part 6 Laser beam 7 CCD camera 8 Laser output head 9 Optical fiber 10 Reflective mirror 11 Condensing lens 12 Infrared Light blocking filter 13 Cooling air 14 High pressure gas 15 Laser processing head 16 Water cooling jacket 17 Laser light passing nozzle 18 High pressure gas nozzle 19 Thermal spray flame burner 20 Powder refractory
Wm Width of melted / resolidified part dm Depth of melted / resolidified part wg Width of groove part dg Depth of groove part t Refractory brick remaining thickness in groove part
t ₀ refractory brick thickness

Claims (5)

A hot repair method for a coke oven that repairs hot cracks in a refractory brick furnace wall that separates a carbonization chamber and a combustion chamber of a coke oven,
Detecting the crack position;
A step of irradiating a laser beam to the crack portion and the periphery thereof along the crack to melt and resolidify the refractory brick around the crack portion to close the crack portion. Hot repair method for the furnace. A hot repair method for coke oven cracks, in which a crack generated in a refractory brick furnace wall separating the carbonization chamber and the combustion chamber of the coke oven is repaired hot,
Detecting the crack position;
Along the crack, irradiate a laser beam to melt the refractory brick, and eject a high-pressure gas to remove the molten refractory brick to form a groove, and
And a step of spraying a powder refractory along the groove to fill the groove and the crack. In the step of melting the refractory brick by the laser irradiation and injecting the high-pressure gas to remove the molten refractory brick to form the groove portion, the temperature of the high-pressure gas is 300 ° C. or higher and 1000 ° C. or lower. The hot repair method for a coke oven according to claim 2. The width of the groove formed by the laser irradiation Wg, the depth dg, when the refractory bricks thickness was t _o, Wg is not less 10mm or more, refractory bricks remaining thickness t = t ₀ -dg of the groove forming portion The hot repair method for a coke oven according to claim 2 or 3, wherein the hot repair method is 30mm or more. The refractory brick is a silica brick having a SiO2 content of 93 wt% or more, and at least one of the temperature of the refractory brick or the atmosphere temperature in the furnace is 300 ° C or higher and 1800 ° C or lower. 4. A hot repair method for a coke oven according to any one of 4 above.

Images