JP2004359978A - How to prevent temperature drop in hot gas supply system - Google Patents

Abstract

A hot air main pipe between a take-out pipe located at the uppermost stream in a flow direction of a hot gas and an adjacent take-out pipe can be uniformly heated, and the pressure of the hot gas flowing inside the hot-air main pipe can be increased. Provided is a method for preventing a temperature drop of a hot gas supply system which can be applied to a large-diameter hot air main pipe without misfiring due to fluctuations.
A high-hot gas supply comprising extraction pipes (13a-13c) communicating with the hot-blast furnaces (1a-1c) for extracting high-temperature gas, and a hot-air main pipe (3) communicating with the extraction pipe and conveying the high-temperature gas extracted. In the system 0, a heating device that has a total length substantially between the inside of the hot air main pipe and between the take-out pipes and that heats the hot air main pipe by radiant heat from the outer surface thereof is provided with a hot air main pipe. The hot air main pipe is heated by providing a gap between the hot air main pipe, thereby preventing the temperature of the hot gas supply system from lowering.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for preventing a temperature drop of a hot gas supply system. More specifically, the present invention relates to a method for preventing a temperature drop in a hot gas supply system having a hot air main pipe which is a hot gas pipe lined with bricks or irregular refractories on its inner surface.
[0002]
[Prior art]
Usually, a plurality of hot blast stoves for blowing hot air to the blast furnace are provided for each blast furnace, and each hot blast stove blows hot air to the blast furnace sequentially while repeating combustion, charging and blowing. Ventilation from the hot blast stove to the blast furnace is performed by lining a plurality of outlet pipes connected to each hot blast stove and a hot air main pipe connected to the plurality of outlet pipes with a brick, inside diameter: several meters, length : Via a hot gas line of less than 10 meters. Hot air of 950 to 1200 ° C. normally flows inside the hot air main pipe, and the bricks on the inner surface are heated to a temperature close to the temperature of the hot air.
[0003]
Conventionally, bricks in the hot blast stove have been replaced at the time of blast furnace renovation.Recently, in order to improve the operation rate of the blast furnace, only the hot stove that replaces the bricks has been stopped, so that even during the operation of the blast furnace, Is being done. Each outlet pipe is provided with an on-off valve for shutting off the flow of the hot gas in order to switch the ventilation from the plurality of hot blast stoves. For example, when the bricks of the hot blast stove connected to the take-out pipe located at the most upstream in the flow direction of the hot gas are reloaded during the operation of the blast furnace, the bricks are provided at the take-out pipe located at the most upstream in the flow direction of the hot gas. Close the open / close valve.
[0004]
However, when this on-off valve is closed, the hot gas flows into the hot air main pipe between the take-out pipe located at the most upstream in the flow direction of the hot gas and the take-out pipe adjacent to the take-out pipe located at the most upstream. It stops flowing. For this reason, bricks or irregular refractories lined on the inner surface of this portion gradually cool down. Bricks lined on the inner surface of the hot air mains, which have been used for a long time, have already deteriorated due to creep, and the joints between the bricks have become loose. For this reason, if the temperature of a brick falls extremely, it may collapse.
[0005]
Therefore, in order to prevent the collapse of the bricks of the hot air main when the bricks of the hot air stove connected to the take-out pipe located at the uppermost stream in the flow direction of the hot It is necessary to heat the hot air main pipe between the take-out pipe located at the most upstream in the direction and the take-out pipe adjacent to the take-up pipe located at the most upstream to prevent an extreme temperature drop.
[0006]
For example, in Patent Literature 1, a hot air outlet pipe section opens a furnace wall, a hot air plate is inserted in a horizontal direction of a combustion chamber, and a dome brick and a heat storage chamber brick are kept in a combustion chamber on an upper side of a heat insulating plate. An invention is disclosed in which a provisional combustion burner is provided and the combustion chamber below the heat shield is forcibly cooled. According to the invention disclosed in Patent Literature 1, it is possible to heat the hot air main pipe while the temporary combustion burner is burning.
[0007]
[Patent Document 1]
JP-A-52-29404
[Problems to be solved by the invention]
The present invention is based on the premise that the interior of the hot air mains is at atmospheric pressure. However, the hot blast main pipe inevitably receives pressure fluctuations of the hot gas from the hot blast stove other than the stopped hot blast stove by repeating combustion, charging, and blowing, and therefore, there is a high possibility of a misfire due to this pressure fluctuation.
[0009]
Further, in the present invention, there is also a problem that the combustion exhaust gas is mixed into the high-temperature gas because the temporary combustion burner is directly burned inside the hot air main pipe.
At first glance, it can be considered that the inside of the hot air main pipe may be heated using a radiant tube commonly used as a heat source such as a heating furnace. However, since the length of the radiant tube that can be heated by one radiant tube is short with respect to the area to be heated, a plurality of radiant tubes need to be arranged in parallel. For this reason, deviation tends to occur in heating, and it is not possible to uniformly heat a high-temperature gas pipe such as a hot air main pipe having an inner diameter of several meters and a length of less than 10 meters.
[0010]
An object of the present invention is to uniformly heat a high-temperature gas pipe between a take-out pipe located at the most upstream in the flow direction of the hot gas and a take-out pipe adjacent to the take-up pipe located at the most upstream. High heat that can be sufficiently applied to a large-diameter high-temperature gas line such as a hot-air main line of a hot-blast furnace of a blast furnace without misfiring due to pressure fluctuation of the high-temperature gas flowing inside the high-temperature gas line. An object of the present invention is to provide a method for preventing a temperature drop in a gas supply system.
[0011]
[Means for Solving the Problems]
The present invention relates to a plurality of extraction pipes for communicating with each of a plurality of hot air generators to extract a high-temperature gas, and a high-temperature gas pipeline communicating with the plurality of extraction pipes and conveying the extracted high-temperature gas in one direction. A method for preventing a decrease in temperature of a hot gas supply system comprising: a take-out pipe located at the most upstream in the flow direction of the hot gas inside the hot-gas pipe, and a take-out pipe located at the most upstream A heating device having an overall length substantially between the adjacent take-out pipes and heating the hot gas pipeline by radiant heat from the outer surface is inserted between the adjacent take-out pipes with a gap provided between the heating pipe and the heating apparatus. This is a method for preventing the temperature of the hot gas supply system from dropping by heating the hot gas pipe.
[0012]
In the method for preventing a temperature drop of the hot gas supply system according to the present invention, the heating device has a heat-resistant tube having an outer diameter smaller than the inner diameter of the hot gas pipe and having one end sealed, and a heat-resistant tube. It is desirable to have a burner disposed inside, and to heat the high-temperature gas line by heating a heat-resistant tube by a flame from the burner.
[0013]
Since the diameter of the heat-resistant tube is large and its length is long, a large moment due to its own weight is likely to act on the base of the heat-resistant tube. It is desirable to increase the strength and make it strong. In order to solve this problem, a heat-resistant tube may be supported by a supporting member from the bottom of the high-temperature gas pipeline to reduce the moment generated at the root.
[0014]
Further, in the method for preventing a temperature drop of the hot gas supply system according to the present invention, an opening / closing valve for shutting off the flow of the hot gas is provided in the plurality of outlet pipes, and the hot gas path of the hot gas is controlled by the heating device. It is most effective to perform the heating when the on-off valve provided on the take-out pipe located at the most upstream in the flow direction of the hot gas is closed.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of a method for preventing a temperature drop of a hot gas supply system according to the present invention will be described in detail with reference to the accompanying drawings. In the following description, the present invention is applied to a hot gas supply system to a blast furnace, and the “hot air generator” of the present invention is a hot blast stove that generates hot air to be sent to the blast furnace. Is an example of a hot air mains.
[0016]
FIG. 1 is an explanatory view showing a hot gas supply system 0 having a hot air main pipe 3 which is a hot gas pipe for sending hot air to a blast furnace.
As shown in FIG. 1, this hot gas supply system 0 includes three take-out pipes 13a to 13c for taking out hot gas by communicating with hot blast furnaces 1a to 1c, which are three hot air generators, respectively. A hot air main pipe 3, which is a hot gas pipe, which conveys the hot gas taken out in communication with the three take-out pipes 13a to 13c in one direction. The outlet pipes 13a to 13c are provided with hot air valves 2a to 2c, respectively. The hot air valves 2a to 2c are opened according to the blowing of hot air when the hot air stoves 1a to 1c are operating, and when any of the hot air stoves 1a to 1c is stopped for reloading bricks. It remains closed.
[0017]
In the high-temperature gas supply system 0, the hot-air furnace 1a communicating with the take-out pipe 13a located at the uppermost stream in the flow direction of the high-temperature gas (the direction of the arrow in FIG. 1) is stopped for brick reloading and the hot-air valve 2a is closed. Then, the range 4 on the end side of the hot air main pipe 3, that is, between the take-out pipe 13a located at the most upstream in the flow direction of the hot gas and the take-out pipe 13b adjacent to the take-out pipe 13a located at the most upstream. Since the hot gas stops flowing in the range 4, the heat from the outer surface of the hot air main pipe 3 in the range 4 gradually cools the hot air main pipe 3 in the range 4. When the hot blast main pipe 3 cools, the temperature of the brick (not shown) lined on the inner surface of the hot blast main pipe 3 also decreases, and if the temperature of the brick drops extremely, the bricks may collapse in the worst case. There is a possibility that.
[0018]
Therefore, in the present embodiment, the take-out pipe 13a located inside the hot air main pipe 3 and located at the most upstream in the flow direction of the hot gas, and the take-out pipe 13b adjacent to the take-out pipe 13a located at the most upstream flow. A heating device 9 having an overall length substantially corresponding to this range 4 and heating the hot air main pipe 3 by radiant heat from the outer surface thereof is provided in a gap 4 between the hot air main pipe 3 and the space 4. I do. In other words, the heating of the hot air main pipe 3 by the heating device 9 is performed when the on-off valve 2a provided in the take-out pipe 13a located at the uppermost stream in the flow direction of the hot gas is closed for a long time.
[0019]
FIG. 2 is a cross-sectional view showing a state in which the heating device 9 is arranged in a range 4 between a take-out pipe 13a located at the most upstream stream and a take-out pipe 13b adjacent to the take-up pipe 13a located at the most upstream stream.
[0020]
The heating device 9 has a heat-resistant tube 8 having an outer diameter smaller than the inner diameter of the hot-air main pipe 3 and one end of which is sealed, and a burner 9 a disposed inside the heat-resistant tube 8. The burner 9a is arranged concentrically with the heat-resistant tube 7 arranged inside the tube 8.
[0021]
The heating device 9 heats the hot air main pipe 3 by heating the heat resistant tubes 7 and 8 by the flame from the burner 9a. Hot air is generated by a flame 10 generated from a burner 9 a provided inside the inner heat-resistant tube 7 and passes through the inner heat-resistant tube 7. This hot air collides with the end 11 of the outer heat-resistant tube 8 and passes between the outer heat-resistant tube 8 and the inner heat-resistant tube 7 while heating the outer heat-resistant tube 8. Then, the air is exhausted from the exhaust pipe 12.
[0022]
That is, in the present embodiment, the heating device 9 having the burner 9 a inside the double tube composed of the outer heat-resistant tube 8 and the inner heat-resistant tube 7 is connected to the end of the hot-air main tube 3. The area 4 of the high-temperature gas supply system 0 is heated by being inserted from the opening 6 provided in the apparatus.
[0023]
Since the tubes 8 and 7 used in the present embodiment have a simple structure, a composite material such as a single material such as stainless steel, heat-resistant steel, and ceramics, or a steel-structured tube with a refractory lining is used. A material corresponding to the temperature of the flowing gas, such as a material, can be used.
[0024]
FIG. 3 is an explanatory view showing an example of the support members 14a to 14c that support the heat-resistant tube 8 from the bottom of the hot air main pipe 3.
Several holes are provided in the bottom of the hot air main pipe 3, and support members 14 a to 14 c formed of a refractory are fixed in the holes to support the heat-resistant tube 8. The material of the support members 14a to 14c may be a single material such as stainless steel, heat-resistant steel, or ceramics, or a composite material such as a steel-structured pipe with a refractory lining, in addition to the above-described refractories. A material corresponding to the temperature of the gas can be used. Depending on the temperature conditions, the inside may be water-cooled.
[0025]
FIG. 4 is an explanatory diagram illustrating a structural example of a burner 9b that generates a plurality of flames in a circumferential direction, which will be described later. The burner 9 may be a burner in which a flame is ejected linearly from a general pipe. For example, a plurality of holes are provided in a side surface of the pipe, such as a burner 9a that generates a plurality of flames in a circumferential direction. It is also possible to use an object that emits a flame from the hole. It is desirable to heat the burner 9a while rotating it inside the tube 7, since the tube 8 can be heated very uniformly.
[0026]
As described above, in the present embodiment, the heat-resistant tube 8 having an outer diameter smaller than the inner diameter of the hot-air main pipe 3 and having one end sealed is inserted into the hot-air main pipe 3, and the inside of the hot-air main pipe 3 is gas burner. By heating by 9a, the brick 5 on the inner surface of the hot air main pipe 3 is indirectly heated by the heat released from the outer surface of the heated outer heat-resistant tube 8.
[0027]
In the present embodiment, the hot air main pipe 3 is heated by the heating device 9 in this way, thereby preventing the temperature of the hot gas supply system 0 from lowering. For this reason, since the area where the flame 10 is formed is completely separated from the hot air main pipe 3, the flame 10 is misfired due to pressure fluctuation when the high-temperature gas flows, or the combustion exhaust gas is mixed into the hot air. And other issues are resolved.
[0028]
In addition, since the flow direction of the flame 10 generated from the burner 9a can be controlled by the heat-resistant tube 7, the deviation of the heating becomes extremely small, and the hot air main pipe 3 can be heated very uniformly.
[0029]
Further, by controlling the combustion state of the burner 9a, the heating temperature of the hot air main pipe 3 can be freely changed.
Further, the supply can be performed at a low cost with a simple structure.
[0030]
As described above, according to the present embodiment, the bricks 5 on the inner surface of the hot air main pipe 3 can be uniformly heated to an appropriate temperature, so that the hot air furnace 13a is stopped and repair such as reloading of the internal bricks is performed. It is possible to extend the life of the hot blast stove of the blast furnace without lowering the productivity of the blast furnace.
[0031]
【The invention's effect】
As described above, according to the present invention, the hot gas line between the take-out pipe located at the most upstream in the flow direction of the hot gas and the take-out pipe adjacent to the take-up pipe located at the most upstream is made uniform. It can be heated to a large diameter hot gas line such as a hot air main line of a blast furnace hot air stove without misfiring due to the pressure fluctuation of the high temperature gas flowing inside the high temperature gas line. A method for preventing the temperature of the hot gas supply system from decreasing can be provided.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a hot gas supply system having a hot air main pipe which is a hot gas pipe for sending hot air to a blast furnace.
FIG. 2 is a cross-sectional view showing a state in which a heating device is arranged in a range between a take-out pipe located at the most upstream stream and a take-out pipe adjacent to the take-up pipe located at the most upstream stream.
FIG. 3 is an explanatory view showing an example of a support member that supports a heat-resistant tube from the bottom of a hot air main pipe.
FIG. 4 is an explanatory diagram showing a structural example of a burner that generates a plurality of flames in a circumferential direction.
[Explanation of symbols]
0 Hot gas supply system 1 Hot blast stove 2 Hot blast valve 3 Hot blast main pipe 4 Range of end side of hot blast main pipe 5 Brick 6 Opening 7 Inside heat resistant tube 8 Outside heat resistant tube 9 Heating device 9a Burner 10 Flame 11 End 12 Exhaust pipe 13 Extraction pipe 14a to 14c Support member

Claims (4)

A high-temperature heat source including a plurality of extraction pipes communicating with the plurality of hot air generators to extract the high-temperature gas, and a high-temperature gas pipe communicating with the plurality of extraction pipes and conveying the extracted high-temperature gas in one direction; A method for preventing a temperature drop of a gas supply system,
Inside the high-temperature gas pipe, between the take-out pipe located at the most upstream in the flow direction of the hot gas, and the take-out pipe adjacent to the take-up pipe located at the most upstream, the total length extending substantially between them is A heating device that has the heating device for heating the high-temperature gas pipeline by radiant heat from the outer surface thereof is provided by providing a gap between the high-temperature gas pipeline and the high-temperature gas pipeline. A method for preventing a temperature drop in a hot gas supply system. The heating device includes a heat-resistant tube having an outer diameter smaller than the inner diameter of the high-temperature gas pipe and having one end sealed, and a burner disposed inside the heat-resistant tube. The method for preventing a temperature drop of a hot gas supply system according to claim 1, wherein the hot gas pipe is heated by heating the heat-resistant tube with a flame from the heat source. 3. The method of claim 2, wherein the heat-resistant tube is supported by a heat-resistant support member provided at the bottom of the high-temperature gas pipe. The plurality of outlet pipes are provided with an on-off valve for shutting off the flow of the high-temperature gas, and the heating of the high-temperature gas pipe by the heating device is performed at the highest position in the direction of flow of the high-temperature gas. 4. The method for preventing a temperature drop of a hot gas supply system according to any one of claims 1 to 3, wherein the method is performed when the on-off valve provided in the apparatus is closed.

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