JP2011225939A - Continuous heating furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a continuous heating furnace which is provided with regenerative burners arranged on both side walls of an upper zone and a lower zone of a preheating area and a heating area, and roof burners or axial-flow burners in an upper zone of a soaking area, and which is capable of inhibiting black smoke from blowing out from clearances of an extracting door of the continuous heating furnace.SOLUTION: The continuous heating furnace is provided with a charging door 21 for charging a billet in one side of the furnace body, an extracting door 22 for extracting the billet in another side, regenerative burners arranged on both side walls in a preheating area 5 and heating areas 6 and 7, roof burners 17a arranged in a ceiling portion of a soaking area 8, and regenerative burners arranged in both side walls of a lower zone 10 of the soaking area 8, wherein a partition wall 23 crossing the furnace body and having a height lower than a walking beam is erected on a hearth between the regenerative burner 27b located nearest the extraction side among the regenerative burners in the lower zone of the soaking area 8 and the regenerative burner 28b adjacent thereto.

Description

  The present invention relates to a continuous heating furnace that continuously heats steel pieces such as slabs and billets.

  As a continuous heating furnace for continuously heating steel pieces such as slabs and billets, a continuous heating furnace equipped with a regenerative burner (thermal storage burner) is used. The continuous heating furnace will be described below with reference to the drawings.

  4 is a sectional view of a conventional continuous heating furnace equipped with a regenerative burner, FIG. 5 is a plan view of an upper zone of the continuous heating furnace shown in FIG. 4, and FIG. 6 is a lower portion of the continuous heating furnace shown in FIG. FIG. 7 (a) is a sectional view of the pre-tropical zone and heating zone of the furnace shown in FIG. 4, and FIG. 7 (b) is a sectional view of the soaking zone of the furnace shown in FIG.

  Regenerative burners 11a, 11b to 16a, 16b, which are opposed to each other, are arranged on both side walls of the pre-tropical zone 5, the heating zone A6, and the upper zone 9 and the lower zone 10 of the heating zone B7 of the furnace 1 of the continuous heating furnace. Regenerative burners 18 a and 18 b are arranged in the lower zone 10 of the soaking zone 8. Roof burners 17a and 17b are arranged on the ceiling of the furnace body in the upper zone 9 for the purpose of increasing the heating temperature in the longitudinal direction (furnace width direction) of the steel slab for the purpose of improving quality by rolling in the subsequent process. Has been. The upper zone 9 and the lower zone 10 are provided with partition walls 19 that partition the bands 5 to 8 at the boundaries of the bands 5 to 8.

  The steel slab 3 is inserted into the furnace by opening the charging door 21, and is being conveyed to the pre-tropical zone 5, the heating zone A 6, the heating zone B 7, and the soaking zone 8 by the walking beam 4 shown in FIG. Heated, the extraction door 22 is opened and carried out of the system. The exhaust gas combusted and discharged from the burner is discharged from the flue 2 to the outside of the system.

  FIG. 8 is a cross-sectional view of a conventional continuous heating furnace having another structure, and FIG. 9 is a plan view of the upper zone of the furnace shown in FIG. The difference between the configuration of this continuous heating furnace and the conventional continuous heating furnace shown in FIGS. 4 to 7 is that axial flow burners 20a and 20b are arranged in place of the roof burner at the ceiling of the soaking zone. The other configurations are the same.

  By the way, in order to reduce NOx, the regenerative burner disposed in the conventional both heating furnaces is generally in the form of slow combustion with the combustion air and fuel inlets separated. When such a regenerative burner with the combustion air and fuel inlets separated is used, in the regenerative burner arranged on the most extraction side (extraction door side), the extraction front wall 24 exists on the extraction door 22 side, so the burner Combustion air and fuel gas blown into the furnace are sucked toward the extraction front wall 24 and flow in the furnace width direction while slowly burning along the extraction front wall 24. On the other hand, since it is impossible to completely seal the extraction door 22 portion of the heating furnace, the pressure inside the furnace is set to a positive pressure to prevent intrusion of outside air from the extraction door 22 portion, and the exhaust gas in the furnace near the extraction door 22 is prevented. Is always discharged out of the furnace through the gap of the extraction door 22 portion, but unburned fuel due to slow combustion becomes a gas flow 25 along the extraction front wall 24 as shown in FIG. There is a problem that black smoke is blown out from the gap between the parts and pollutes the environment.

  Patent Document 1 discloses a technique for preventing black smoke from the extraction door 22 described above. In Patent Document 1, in a continuous heating furnace in which a regenerative burner is opposed to both sides of a furnace body in a soaking zone in the upper zone, the exhaust gas flow in the furnace is improved, and the unburned fuel flows into the extraction door. It shows how to prevent blowing out of the gap.

JP 2008-240133 A

  However, in the technique described in Patent Document 1, a roof burner or an axial flow burner is disposed on the ceiling of the soaking zone, which is the subject of the present invention, and a regeneration burner is used only in the lower zone. Since the exhaust gas flow in the furnace of the conventional continuous heating furnace cannot be improved, as described above, the problem that unburned fuel blows out as black smoke from the gap of the extraction door and pollutes the environment is solved. I can't.

  Accordingly, the present invention provides a continuous heating furnace in which a gene burner is arranged on both side walls of the pre-tropical zone, the upper zone and the lower zone of the heating zone, and a roof burner or an axial flow burner is arranged in the upper zone of the soaking zone. The present invention provides a continuous heating furnace capable of suppressing black smoke from blowing out from a gap between doors.

  The present invention has a billet loading door at one end of a furnace body in which the pre-tropical zone, heating zone and soaking zone are sequentially arranged in the billet conveyance direction, and a billet extraction door at the other end. A pair of regenerative burners are arranged opposite to both side walls of the upper zone and lower zone of the tropical zone and the heating zone, and a roof burner or an axial flow burner is placed on the ceiling of the upper zone of the tropical zone. In a continuous heating furnace in which a plurality of regenerative burners that are paired facing both side walls of the lower zone are arranged, among the plurality of regenerative burners arranged in the lower zone of the soaking zone, it is located on the most extraction side A partition wall that crosses the furnace body and has a height lower than that of the walking beam is erected on the hearth between the pair of regenerative burners and the pair of adjacent regenerative burners.

  Further, according to the present invention, in the above configuration, the furnace body longitudinal direction between the pair of regenerative burners located on the most extraction side and the partition wall in the furnace body longitudinal direction between the pair of regenerative burners and the extraction front wall Or a coating material is applied to the standing surface on the extraction side of the partition wall.

  In the present invention, the fuel gas and the combustion air blown from the pair of regenerative burners located on the most extraction side among the regenerative burners arranged on both side walls of the furnace body in the lower zone of the soaking zone are erected from the hearth. By flowing along the partition wall, the time required for the combustion air and fuel gas to complete combustion in the furnace is secured, and the combustion air and fuel gas can be completely burned in the furnace. It is possible to prevent the unburned portion in the middle of combustion from being blown out as black smoke from the gap of the extraction door.

It is sectional drawing of the continuous heating furnace which arrange | positioned the partition wall of this invention. It is a top view of the lower zone shown in FIG. FIG. 3 is a partially enlarged view of a soaking zone in the lower zone shown in FIG. 2. It is sectional drawing of the conventional continuous heating furnace which arrange | positioned the roof burner in the soaking zone upper zone. FIG. 5 is a plan view of the upper zone of the furnace shown in FIG. 4. FIG. 5 is a plan view of the upper zone of the furnace shown in FIG. 4. (A) is the pre-tropical zone of the furnace shown in FIG. 4, (b) is a cross-sectional view of the soaking zone. It is sectional drawing of the conventional continuous heating furnace which arrange | positioned the axial-flow burner in the soaking zone upper zone. It is a top view of the upper zone of the furnace shown in FIG. FIG. 9 is a partially enlarged view of a soaking zone in the lower zone shown in FIG. 4 or FIG. 8.

  Embodiments of the present invention will be described with reference to the drawings.

  The furnace body of the continuous heating furnace of the first embodiment is substantially the same as the conventional continuous heating furnace provided with the roof burner shown in FIGS. That is, as shown in FIG. 1, the furnace body 1 is divided into four zones, a pre-tropical zone 5, a heating zone A 6, a heating zone B 7, and a soaking zone 8, in the direction of conveying and heating the steel material 3 that is the object to be heated. Has been. Regenerative burners 11a, 11b to 16a, 16b, which are opposed to each other, are disposed on the side walls of the furnace zone 1 in the upper zone 9 and the lower zone 10 of the pre-tropical zone 5, heating zone A6, and heating zone B7. A plurality of roof burners 17a and 17b are disposed in the ceiling portion of the furnace body 1 in the upper zone 9, and regenerative burners 18a and 18b are disposed in the lower zone, and a partition wall 19 is provided to partition each band.

  The steel piece 3 is inserted into the furnace from a charging door 21 provided on one side of the furnace body 1, heated and soaked during conveyance in the furnace, and extracted on the other side of the furnace body 1. It is taken out of the system from the door 22. The above is the same as the structure of the conventional continuous heating furnace as described above.

  In the first embodiment, as shown in FIGS. 1 to 3, a pair of regenerative burners 27 a and 27 b located closest to the extraction side is provided in the vicinity of the extraction front wall 24, and adjacent to the burners 27 a and 27 b. A pair of regenerative burners 28a and 28b is provided.

  A partition wall 23 that crosses the furnace body 1 on the hearth and has a height lower than that of the walking beam 4 between the longitudinal side of the furnace body of the burners 27a and 27b on the most extraction side and the burners 28a and 28b adjacent to the burner. Is erected. The partition wall 23 is configured by, for example, building a refractory brick, similarly to the partition walls 19 of the bands 5 to 8.

  In FIG. 3, when the regenerative burner 27 b on the lower side is burning, the flow of combustion gas and air is in the state indicated by the arrow 26 along the partition wall 23. The fuel gas and the combustion air blown from the burner 27b flow along the partition wall 23 due to the Coanda effect because the partition wall 23 standing from the hearth exists, and both of them complete the combustion in the furnace. The necessary time is ensured and it burns completely in the furnace. Thereby, it can prevent that the unburned part in the middle of combustion turns into black smoke and blows out from the clearance gap of the extraction door 22. FIG.

  The distance in the furnace longitudinal direction between the pair of regenerative burners 27a, 27b located on the most extraction side and the partition wall 23 is shorter than the distance between the pair of regenerative burners 27a, 27b and the front wall 24 in the furnace longitudinal direction. By doing so, it becomes possible to further increase the Coanda effect, and it is possible to reliably prevent unburned fuel from blowing out from the gap of the extraction door 22.

  Furthermore, if a coating material is applied to the standing surface of the refractory brick on the extraction side of the partition wall 23, the Coanda effect can be further increased, and unburned fuel from the gap of the extraction door 22 can be blown out. It can be surely prevented. In addition, as a coating material apply | coated to a refractory brick, the spraying material etc. which have a heat resistant alumina as a main component are preferable.

  The furnace body of the continuous heating furnace of Example 2 is substantially the same as the conventional continuous heating furnace provided with the axial flow burner shown in FIG.

  The only difference from the first embodiment shown in FIGS. 4 to 7 is that an axial flow burner is disposed in place of the roof burner at the ceiling of the upper zone in the soaking zone, and the configuration of other partition walls, etc. Are identical. That is, as in Example 1, a partition wall that crosses the furnace body and has a height lower than that of the walking beam on the hearth between the pair of regenerative burners located on the most extraction side and the adjacent pair of regenerative burners. Provided.

  Also in the second embodiment, as in the first embodiment, the fuel gas and the combustion air blown from the pair of regeneration burners located on the most extraction side by the partition wall flow along the partition wall and burn in the furnace. Since the time required to complete the process is ensured and combustion is completely performed in the furnace, it is possible to prevent the unburned part during combustion from being blown out from the gap of the extraction door.

1: Continuous heating furnace body 2: Flue 3: Steel slab
4: Walking beam 5: Pre-tropical
6: Heating zone A
7: Heating zone B
8: Soaking zone 9: Upper zone 10: Lower zone 11a, 11b-16a, 16b: Regenerative burner 17a, 17b: Roof burner
18a, 18b: Regenerative burner 19: Partition wall of each band
20a, 20b: Axial flow burner 21: Loading door 22: Extraction door 23: Partition wall 24: Extraction wall 25: Gas flow 26: Gas flow 27a, 27b: Regenerative burners 28a, 28b located on the most extraction side : Regeneration burner adjacent to regeneration burner 27

Claims (3)

Pre-tropical zone, heating zone and soaking zone are sequentially arranged in the conveying direction of the steel slabs. The furnace body has a billet loading door at one end and a billet extraction door at the other end. A plurality of regenerative burners are arranged opposite to the both side walls of each upper zone and lower zone, and a roof burner or an axial flow burner is placed on the ceiling of the soaking zone. In a continuous heating furnace in which a plurality of regenerative burners that are opposed to both side walls are arranged,
Among the plurality of regenerative burners arranged in the lower tropical zone, between the pair of regenerative burners located closest to the extraction side and the pair of regenerative burners adjacent to the regenerative burner, A continuous heating furnace characterized in that a partition wall lower than the walking beam is installed on the hearth.   The distance between the pair of regenerative burners located on the most extraction side and the partition wall in the longitudinal direction of the furnace body is shorter than the distance between the pair of regenerative burners and the front wall of the extraction body in the longitudinal direction of the furnace body. The continuous heating furnace according to claim 1.   The continuous heating furnace according to claim 1 or 2, wherein a coating material is applied to a standing surface on the extraction side of the partition wall.

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