JP2007314821A - Method for intercepting heat at repairing time of hot-blast tube line - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for intercepting the heat at repairing time of a hot-blast tube line with which an optional position in the hot-blast tube line can be quickly heat-intercepted at a low cost. <P>SOLUTION: The method for intercepting the heat at the repairing time of the hot-blast tube line, is constituted by including the following processes, that is; a draft-blasting forming process, in which the draft-blasting for cooling this repairing scheduled part, is formed by arranging the opening part in the hot-blast tube line 11 and by making flow of the outer air under state of passing through the repairing scheduled part in the hot-blast tube line from the above opening part; a gas permeable member setting process, in which the gas permeable member, interceptable against the radiant heat is carried to a heat intercept scheduled position at the downstream side of the draft-blasting from the above repairing scheduled part in the hot-blast tube line from the above opening part along the flowing of the draft-blasting and set it to the heat intercept scheduled position; and a refractory wall constructing process for constructing the refractory wall at the position adjoined to the gas permeable member set in the hot-blast tube line under state of closing the inner part of the hot-blast tube line by using the refractory member. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for thermally shutting off the inside of a hot air duct when repairing a hot air duct connecting a hot stove equipped with a combustion chamber and a heat storage chamber and a tuyere of a blast furnace.

  The hot stove is a regenerative heat exchanger that heats air in order to blow hot air from the tuyere of the blast furnace, and includes a combustion chamber and a heat storage chamber. Usually, three to four hot blast furnaces are provided for one blast furnace, and operation is performed by alternately switching between combustion and blowing in each hot blast furnace. Inside the heat storage chamber, bricks with a large number of gas ventilation holes called checker bricks are stacked, and the checker bricks play a role of storing heat generated when combustion gas is burned in the combustion chamber. .

  In such a hot air furnace, when hot air is sent to the tuyeres of the blast furnace, air is sent to the heated checker bricks to form hot air, and this hot air is separated into the hot air furnace and the tuyere of the blast furnace. It is circulated to the tuyere of the blast furnace through a hot air duct such as a hot air main pipe to be connected. At this time, the temperature of the blown air from the hot stove is as high as 1100 to 1300 ° C., and the refractory that forms the inner wall of the hot air duct is deteriorated by long-term use. For this reason, it is necessary to repair the inner wall of the hot air duct at a predetermined time.

  Such repair of the inner wall of the hot air duct is usually carried out at the same time when a large-scale refurbishment with a refurbishment period of about 80 to 120 days, such as refurbishment of the blast furnace body, is performed. Here, in a predetermined hot stove, the combustion chamber or the heat storage chamber may not be repaired, and in order to maintain the high temperature state of the combustion chamber or the heat storage chamber, a heat retaining process such as burner heating may be performed. In this case, since heat flows from the combustion chamber to the hot air duct side due to the heat retaining treatment, the heat from the combustion chamber side must be shut off before repairing the inner wall of the hot air duct.

  In addition, for repairing the inner wall of the hot air duct, for example, a rest period (several hours to several days / time) in which the supply of hot air to the blast furnace is stopped in order to repair the furnace body of the blast furnace and other attached equipment. ) Etc. may be implemented. In this case, the temperature of the combustion chamber / heat storage chamber is approximately the same as the temperature during operation, and the blast furnace side is also in a high temperature state. For this reason, the heat from the combustion chamber side or the blast furnace side must be shut off, and only the hot air duct must be cooled to a temperature at which repair work can be performed before repairing the inner wall of the hot air duct.

  As described above, when repairing the inner wall of the hot air duct, heat is reliably and quickly between the hot air duct and the combustion chamber side or blast furnace side under conditions where the combustion chamber side or blast furnace side is in a high temperature state. Technology that can be shut off is required.

Here, conventionally, in order to repair the ceramic burner below the combustion chamber, a method of providing a heat insulation dome between the upper portion of the combustion chamber and the lower portion of the combustion chamber to shut off the heat is known (for example, see Patent Document 1). .
The configuration described in Patent Document 1 includes a heat-insulating dome, an openable / closable support beam for supporting the heat-insulating dome, a support mechanism for moving the support beam up and down, and a main body frame to which the support mechanism is attached. A heat shield is shown. The heat-insulating dome is formed by sewing a fire-resistant fiber cloth and is a folding type that swells by air blowing.
When installing such a heat shield in the combustion chamber, the manhole provided at the boundary between the ceramic burner and the combustion chamber is opened. Then, the heat insulating device is transferred onto the work deck in front of the one side manhole, and the main body frame of the heat insulating device is carried into the facing manhole. After that, the support beam is raised by the support mechanism, then the support beam is opened, and the heat insulation dome is inflated to complete the installation of the heat shield. In this state, the upper part of the combustion chamber above the heat-insulating dome, the lower part of the combustion chamber below and the ceramic burner are completely cut off.

JP-A-8-325615

  Here, it is conceivable to divert the technique described in Patent Document 1 when repairing the inner wall of the hot air duct. Thereby, it is considered that heat can be shut off between the hot air duct and the combustion chamber side or the blast furnace side under the condition that the combustion chamber / heat storage chamber or the blast furnace side is in a high temperature state.

However, in the configuration described in Patent Document 1, since the configuration of the heat insulating device such as providing a support mechanism for moving the support beam up and down is large, the device cost may be increased.
In addition, a configuration for installing the heat-insulating device, such as installing the heat-insulating device after the work deck is installed in front of the manhole, is also large. For this reason, the work load for installing the heat shield, such as a load when handling the heat shield and the work deck, is increased, and the work cost may be increased.
Further, since the heat-insulating dome is installed at a position where the support beam is raised by the support mechanism, there is a limit to the position where the support beam can be extended by the support mechanism. For this reason, there is a limit also in the range which can install a heat insulation dome, and there exists a possibility that a heat insulation dome cannot be installed in the desired location of a hot air duct.

  An object of the present invention is to provide a heat blocking method at the time of repairing a hot air duct that can quickly shut off heat at an arbitrary position of the hot air duct at low cost.

  The present invention is capable of quickly shutting off heat at a low cost and quickly at any position of the hot air duct by transporting the air-permeable member along the draft air flow that cools the scheduled repair portion in the hot air duct. It was devised based on the knowledge. Therefore, the gist of the present invention is as follows.

(1) When the hot air duct repairing the hot air duct connecting the hot air furnace equipped with the combustion chamber and the heat accumulator and the tuyere of the blast furnace, A method for shutting off the inside of the air, wherein an opening is provided in the hot air duct, and the repair planned part is cooled by circulating outside air through the opening to pass the repair planned part in the hot air duct A draft wind forming step for forming a draft wind, and a breathable member capable of blocking radiant heat, the draft wind from the opening to the repaired portion in the hot air duct along the draft wind flow. The air-permeable member is installed at the heat shut-off scheduled position on the downstream side of the air-permeable member, and the fire-resistant member is installed at a position adjacent to the air-permeable member installed in the hot air duct. Used to close the hot air duct A refractory wall constructions constructing a fire wall, characterized in that it is configured to include.

Here, in the present invention, the hot air duct is repaired under the condition that the combustion chamber side or the blast furnace side is in a high temperature state during, for example, the repair of the furnace body portion of the blast furnace or the rest period.
The draft air forming step must be performed after confirming that a predetermined flow path is secured so that hot air does not blow out from the combustion chamber side or the like when the opening is provided.
Moreover, it is preferable to implement the air-permeable member installation step after confirming that the temperature at the heat cutoff scheduled position in the hot air duct has been lowered to a repairable level (for example, about 50 ° C.). Furthermore, as a method of transporting the air-permeable member, for example, an operator wearing a cool suit holds and transports it, attaches the air-permeable member to a moving device that can move in the hot air duct, and transports it, etc. Can be illustrated.
And, in the fire wall construction process, as a method of constructing the fire wall, for example, a plurality of fire bricks are transported by the worker or the moving device etc., and the fire walls are stacked by manually stacking these fire bricks. For example, it can be constructed.

According to such an invention, an arbitrary position of the hot air duct can be quickly shut off at low cost.
That is, in the draft air forming process, the hot air duct is cooled to a level that can be repaired by the draft air, and in the air permeable member installation process, the air permeable member is carried in along the flow direction of the draft air. At this time, although the inside of the hot air duct is sufficiently cooled and no hot air flows, radiant heat is generated from the combustion chamber or the like toward the worker being carried in. In this respect, since the radiant heat can be blocked by the air-permeable member, it is possible to prevent a worker who is carried in from being exposed to the radiant heat. In addition, since the draft air can pass through the air-permeable member, the draft air circulation is not hindered. Therefore, the safety at the time of carrying in can be ensured.
This makes it possible to build a fire wall safely in the fire wall construction process, and by installing a fire wall and a breathable member, it is possible to reliably shut off heat at the planned heat shutoff position in the hot air duct. it can. Such a heat cutoff scheduled position can be arbitrarily set at any position as long as it is within a range in which the draft air in the hot air duct flows. In addition, the cooling time in the hot air duct by the draft air, the installation time of the breathable member and the fireproof wall are short, and the heat shielding work can be completed quickly.
Moreover, since it is a simple structure which conveys and installs the breathable member and the refractory member constituting the refractory wall, a large-scale apparatus or the like is not necessary, and the labor required for each process can be reduced. For this reason, the apparatus cost and work cost which are required for heat insulation work can be reduced.
Therefore, according to the present invention, it is possible to quickly shut off heat at an arbitrary position of the hot air duct at low cost.

(2) The heat blocking method at the time of hot air duct repair according to the present invention is the method of heat blocking at the time of hot air duct repair described in (1) above, wherein the hot air furnace has the combustion chamber and the heat storage chamber. Each is provided as an independent substantially cylindrical structure, and is an external combustion type hot stove having a structure in which the respective dome portions of the combustion chamber and the heat storage chamber are connected by a connecting pipe.
ADVANTAGE OF THE INVENTION According to this invention, when a hot stove is an external combustion type hot stove, the arbitrary positions of the hot air duct which connects the said hot stove and the tuyere of a blast furnace can be heat-blocked quickly at low cost.

(3) The heat shutoff method at the time of hot air duct repair according to the present invention is the heat shutoff method at the time of hot air duct repair as described in (1) above, wherein the hot air furnace is located inside one substantially cylindrical structure. Is an internal combustion type hot stove having a structure in which the combustion chamber and the heat storage chamber are provided by partitioning a wall with a refractory brick wall.
ADVANTAGE OF THE INVENTION According to this invention, when a hot stove is an internal combustion type hot stove, the arbitrary positions of the hot air duct which connects the said hot stove and the tuyere of a blast furnace can be heat-blocked quickly at low cost.

(4) The heat blocking method at the time of hot air duct repair according to the present invention is the heat blocking method at the time of hot air duct repair according to any of the above (1) to (3), wherein the breathable member is made of metal The wire mesh is made of a material, and the wire mesh is formed in a planar shape smaller than the cross section in the direction perpendicular to the axis of the hot air duct.

  According to such an invention, in the breathable member installation process, if the breathable member is held in a state where the wire mesh is substantially orthogonal to the axial direction of the hot air duct, the radiant heat from the combustion chamber side or the like is transferred during transportation. Can be suitably cut off, and the draft can be satisfactorily passed through the wire mesh. By constructing the air-permeable member using a wire mesh, the cost of the apparatus used for heat shielding the inside of the hot air duct can be reduced. Further, since the wire mesh is a lightweight member, it can be easily transported. Furthermore, since the wire mesh is formed in a planar shape smaller than the cross section in the direction perpendicular to the axis of the hot air duct, the wire mesh does not hit the inner wall of the hot air duct. Therefore, work efficiency can be improved.

(5) The heat shutoff method at the time of hot air duct repair according to the present invention is the heat shutoff method at the time of hot air duct repair described in (4) above, wherein the breathable member includes a plurality of the wire meshes. Each of the wire meshes is disposed in a state of facing each other with a predetermined interval.

According to such an invention, the radiant heat from the combustion chamber side or the like can be reliably blocked by the plurality of metal meshes. In other words, since the radiant heat is straight, the radiant heat from the combustion chamber or the like is stored in the wire mesh on the leading end side in the carry-in direction, and secondarily from the wire mesh to the workers who are carrying in slightly. Radiant heat is generated. Here, the secondary radiant heat can be reliably blocked by providing the wire mesh adjacent to the wire mesh at a predetermined interval. Thereby, it can prevent reliably that the worker etc. who are carrying in are exposed to the radiant heat from the combustion chamber side.
In addition, it is preferable to set the space | interval of metal meshes to 30-100 mm. When the said space | interval is less than 30 mm, the interruption | blocking effect of the secondary radiant heat which generate | occur | produced with the metal net | network of the loading direction front end side is not fully acquired. Moreover, when the said space | interval is larger than 100 mm, there exists a problem that handling of a breathable member is difficult and ventilation performance may fall.
Further, when the amount of radiant heat generated is relatively small, the number of wire meshes may be one.

(6) The heat blocking method at the time of hot air duct repair according to the present invention is the method of heat blocking at the time of hot air duct repair described in (4) or (5) above, wherein the wire mesh is 50 to 200 mesh. It is characterized by using.
By setting the mesh of the wire mesh in such a range, the radiant heat from the combustion chamber side or the like can be sufficiently blocked and the draft air can be passed through well when the breathable member is transported. In addition, when the wire mesh is less than 50 mesh, a sufficient heat shielding effect cannot be obtained, and when the wire mesh exceeds 200 mesh, the air permeability is deteriorated.

(7) The heat blocking method at the time of hot air duct repair according to the present invention is the heat blocking method at the time of hot air duct repair according to any of (1) to (3) above, wherein the breathable member is a ventilation The air-permeable solid is formed in a flat plate shape smaller than the cross-sectional shape in the direction perpendicular to the axis of the hot air duct and has a plurality of through-holes substantially along the thickness direction. It is characterized by being.

According to such an invention, in the breathable member installation step, if the breathable member is held so that the breathable solid is substantially orthogonal to the axial direction of the hot air duct, the breathable solid is on the combustion chamber side during transportation. The radiant heat is stored, and the draft wind passes through the plurality of through holes of the air-permeable solid satisfactorily. With such a simple configuration, it is possible to ensure the safety of the workers and the like that are carried in, and it is possible to keep down the cost of the apparatus used to block the heat in the hot air duct.
Further, since the air-permeable solid is formed in a flat plate shape smaller than the cross section in the direction perpendicular to the axis of the hot air duct, the air-permeable solid does not hit the inner wall of the hot air duct. Therefore, working efficiency can be improved.

(8) The heat shutoff method during hot air duct repair according to the present invention is the heat shutoff method during hot air duct repair according to any of (1) to (7) above, wherein the hot air duct is horizontal. A hot air outlet pipe that is formed in a tubular shape extending substantially in the direction, has one end connected to the combustion chamber, and allows hot air from the heat storage chamber to be introduced into the blast furnace through the combustion chamber, The heat cutoff scheduled position in the breathable member installation step and the fire wall construction step is set in the hot air outlet pipe.

According to such an invention, since the hot air outlet pipe set at the heat cutoff scheduled position extends substantially along the horizontal direction, in the fireproof wall construction process, fire bricks are stacked in the hot air outlet pipe and substantially along the vertical direction. A fire wall can be built. That is, the fire wall can be easily constructed, so that the work efficiency can be improved and the cost required for the heat shielding work can be reduced.
In addition, by setting a heat cutoff scheduled position in the hot air outlet pipe and installing a breathable member and a fireproof wall, it is possible to reliably cut off heat from one side and the other side sandwiching the fireproof wall in the hot air outlet pipe. Thereby, even if the said one side (combustion chamber side) is a high temperature state, the said other side repair work can be implemented.

(9) The heat shutoff method at the time of hot air duct repair according to the present invention is the heat shutoff method at the time of hot air duct repair described in (8) above, wherein the hot air furnace has a tubular shape extending substantially along the horizontal direction. A mixing chamber that is connected to the combustion chamber via a formed connection pipe, mixes cooling air with hot air introduced from the heat storage chamber via the combustion chamber, and adjusts the temperature of the hot air; The hot air outlet pipe is connected to the combustion chamber at the one end side through the mixing chamber, and allows hot air adjusted in the mixing chamber to be introduced into the blast furnace, and the breathable member installation step and the fire wall construction The heat cutoff scheduled position in the process is set in the hot air outlet pipe or in the connection pipe.

According to such an invention, since the hot air outlet pipe or connection pipe set at the heat cutoff scheduled position extends substantially along the horizontal direction, the fire bricks are stacked in the hot air outlet pipe or connection pipe in the fireproof wall construction process. Thus, it is possible to construct a fire wall substantially along the vertical direction. That is, the fire wall can be easily constructed, so that the work efficiency can be improved and the cost required for the heat shielding work can be reduced.
And when the heat cutoff scheduled position is set in the hot air outlet pipe, by installing a breathable member and a fireproof wall at the heat cutoff planned position, one side and the other side sandwiching the fireproof wall etc. in the hot air outlet pipe The heat can be reliably shut off. Thereby, even if the said one side (mixing chamber side) is a high temperature state, the repair work of the said other side can be implemented.
In addition, when a heat cutoff scheduled position is set in the connection pipe, by installing a breathable member and a fireproof wall at the heat cutoff planned position, the one side and the other side sandwiching the fireproof wall etc. in the connection pipe can be securely Can shut off heat. Thereby, even if the said one side (combustion chamber side) is a high temperature state, the repair work of the said other side (the mixing chamber side in a connection pipe | tube, the mixing chamber inside, and a hot-air exit pipe | tube) can be implemented.

(10) The heat shutoff method during hot air duct repair according to the present invention is the hot shutoff method during hot air duct repair described in (9) above, wherein the hot air outlet pipe is hot air that opens and closes the flow path in the pipe. A valve is detachably provided, and a flue pipe is connected to the lower part of the heat storage chamber, and the flue pipe sucks exhaust gas discharged from the combustion chamber through the heat storage chamber to the outside. A dischargeable chimney is provided, and further, a flue valve for controlling the flow of the exhaust gas is provided between the heat storage chamber and the chimney in the flue pipe, and before the draft wind forming step Open the flue valve, and ensure a draft air flow path for the hot air outlet pipe, the mixing chamber, the combustion chamber, the heat storage chamber, the flue pipe and the chimney in order. A flow path securing step is performed, and in the draft wind forming step, the hot air is It said opening provided in the hot air outlet pipe by removing the, and forming the draft air.

According to such an invention, it is possible to prevent hot air from being blown out when the hot air valve is removed from the hot air outlet pipe by securing the draft air flow channel in the draft flow channel securing step. That is, work safety can be ensured.
And, both the hot air outlet pipe and the connection pipe can be cooled by the draft air flowing in order through the hot air outlet pipe, the mixing chamber, the combustion chamber, the heat storage chamber, the flue pipe and the chimney. It can be set anywhere in the connecting pipe. In addition, since the draft wind as described above can be formed by using the existing equipment such as switching the flue valve and removing the hot air valve, it is not necessary to provide a special device for forming the draft wind. Costs and device costs can be reduced.
Draft air also circulates inside the combustion chamber and heat storage chamber, but the cooling rate by the draft air is much higher in the hot air duct and connection pipe than in the combustion chamber and heat storage chamber. While the inside of the chamber is not greatly cooled, the temperature in the hot air duct and the connecting pipe can be lowered to a level that can be repaired. For this reason, the high temperature state of a combustion chamber and a heat storage chamber can be maintained, and the damage etc. resulting from the temperature fall of each dome part in a combustion chamber and a heat storage chamber can be prevented.

(11) The heat blocking method at the time of hot air duct repair according to the present invention is the heat blocking method at the time of hot air duct repair according to any one of the above (1) to (7), wherein the hot air duct is horizontal. A hot air outlet pipe which is formed in a tubular shape extending substantially along the direction, one end of which is connected to the combustion chamber and allows hot air from the heat storage chamber to be introduced into the blast furnace through the combustion chamber; A hot air main pipe formed in a tubular shape extending along the other end of the hot air outlet pipe and connected to the other end of the hot air outlet pipe so that hot air introduced from the hot air outlet pipe can be supplied to the tuyere of the blast furnace. In the breathable member installation step and the fire wall construction step, the heat cutoff scheduled position is set in the hot air outlet pipe or in the hot air main pipe.

According to such an invention, since the hot air outlet pipe or hot air main pipe set at the heat cutoff scheduled position extends substantially along the horizontal direction, the refractory brick in the hot air outlet pipe or hot hot main pipe in the fireproof wall construction process. It is possible to build a fire wall substantially along the vertical direction. That is, the fire wall can be easily constructed, so that the work efficiency can be improved and the cost required for the heat shielding work can be reduced.
And when the heat cutoff scheduled position is set in the hot air outlet pipe, by installing a breathable member and a fireproof wall at the heat cutoff planned position, one side and the other side sandwiching the fireproof wall etc. in the hot air outlet pipe The heat can be reliably shut off. Thereby, even if the said one side (hot air main side) is a high temperature state, the said other side repair work can be implemented.
In addition, when a heat cutoff scheduled position is set in the hot air main pipe, by installing a breathable member and a fireproof wall at the heat cutoff scheduled position, one side and the other side sandwiching the fireproof wall etc. in the hot air main pipe The heat can be reliably shut off. Thereby, even if the said one side (blast furnace side) is a high temperature state, the repair work of the said other side (The hot-air outlet pipe side in a hot-air main pipe and a hot-air outlet pipe) can be implemented.

(12) The heat shutoff method during hot air duct repair according to the present invention is the hot shutoff method during hot air duct repair described in (11) above, wherein the hot air outlet pipe has hot air that opens and closes the flow path in the pipe. A valve is detachably provided, the hot air main pipe is provided with a bleeder that sucks the gas in the flow path in the pipe and discharges it to the outside, and a bleeder valve that controls the flow of the gas to the bleeder, Prior to the draft air forming step, a draft flow passage securing step is performed in which the bleeder valve is opened to secure the draft air flow passage that sequentially flows through the hot air outlet pipe, the hot air main pipe, and the bleeder. In the draft air forming step, the hot air valve is removed to provide the opening in the hot air outlet pipe to form the draft air.

According to such an invention, it is possible to prevent hot air from being blown out when the hot air valve is removed from the hot air outlet pipe by securing the draft air flow channel in the draft flow channel securing step. That is, work safety can be ensured.
And, both the hot air outlet pipe and the hot air main pipe can be cooled by the draft air flowing in order through the hot air outlet pipe, the hot air main pipe and the bleeder, so the heat shut-off scheduled position is set in both the hot air outlet pipe and the hot air main pipe can do. In addition, since the draft wind as described above can be formed by using existing equipment such as switching of the bleeder valve and removal of the hot air valve, it is not necessary to provide a special device for forming the draft wind, and the work cost is reduced. In addition, the apparatus cost can be reduced.

(13) The method for shutting off heat during hot air duct repair according to the present invention is the method for shutting off heat when repairing hot air ducts according to any one of the above (1) to (12). A heat retention step is performed in which combustion gas is combusted in the combustion chamber to maintain the temperatures in the combustion chamber and the heat storage chamber at a high temperature.

  According to such an invention, when the temperature of the combustion chamber / heat storage chamber is lowered due to the circulation of the draft wind, or the high temperature state of the combustion chamber / heat storage chamber is maintained for a long period of time, such as refurbishing the furnace body of the blast furnace. When necessary, the high temperature state of the combustion chamber and the heat storage chamber can be maintained by heat treatment. For this reason, the damage etc. resulting from the temperature fall of each dome part in a combustion chamber and a heat storage chamber can be prevented, and lifetime improvement of a hot stove can be achieved.

  According to the present invention, the air-permeable member is transported along the flow of the draft wind that cools the repair scheduled portion in the hot air duct, thereby preventing the draft wind from flowing from the combustion chamber side or the blast furnace side. Shields radiant heat and easily installs fire walls. As a result, it is possible to quickly shut off heat at an arbitrary position of the hot air duct at low cost.

(1) First Embodiment A first embodiment of the present invention will be described with reference to the drawings. In addition, this embodiment implements repair of the hot air pipe line in the hot air supply system provided with the external combustion type hot stove at the time of repair of the furnace body part of a blast furnace. FIG. 1 is a schematic diagram showing a hot air supply system in the present embodiment.

(1-1) Configuration of Hot Air Supply System In FIG. 1, reference numeral 1 denotes a hot air supply system. This hot air supply system 1 includes three hot air furnaces 2, 3, 4. The hot air is sent to the tuyere (not shown) of the blast furnace 5 by alternately switching between combustion and blowing. Such a hot air supply system 1 includes hot air furnaces 2, 3, 4, combustion gas supply means 6, air supply means 7, flue pipe 8, chimney 9, blower means 10, and hot air duct 11. And is configured. The configuration of the hot stove 2, 3, 4 will be described in detail later.

The combustion gas supply means 6 is connected to the combustion chambers 21 (see FIG. 2) of the hot stoves 2, 3 and 4 and supplies combustion gas to each combustion chamber 21. Examples of the combustion gas include a blast furnace top gas, or a gas whose calorific value is adjusted by adding an appropriate amount of coke oven gas or other fuel thereto.
The air supply means 7 is connected to the combustion chambers 21 of the hot air furnaces 2, 3, 4 and has a predetermined air ratio with respect to the combustion gas from the combustion gas supply means 6. The air is supplied to the combustion chamber 21.
One end side of the flue pipe 8 is branched in three directions, and is connected to the lower part of the heat storage chamber 22 (see FIG. 2) of the hot stove 2, 3, 4 respectively. The exhaust gas after combustion in each combustion chamber 21 circulates inside the flue pipe 8 via the heat storage chamber 22.
The chimney 9 is provided on the other end side of the flue pipe, and can exhaust the exhaust gas from the combustion chamber 21 flowing through the flue pipe 8 and discharge it to the outside.
Further, a flue valve 81 is provided between each heat storage chamber 22 and the chimney 9 in the flue pipe 8. By adjusting the opening of the flue valve 81, the flow rate of the exhaust gas from each heat storage chamber 22 to the chimney 9 is controlled.

The blower means 10 is, for example, a blower or the like, and is connected to the lower part of the heat storage chamber 22 (see FIG. 2) of the hot stove 2, 3, 4 and is connected to the heat storage chamber 22 of the predetermined hot stove 2, 3, 4 The air can be blown.
The hot air duct 11 connects the hot air furnaces 2, 3, 4 and the tuyere of the blast furnace 5, and the hot air formed in each heat storage chamber 22 is blown to the blast furnace 5 through the hot air duct 11. It has become. Such a hot air duct 11 includes a hot air outlet pipe 12, a hot air main pipe 13, and an annular pipe 14.
The hot air outlet pipe 12 is formed in a tubular shape extending substantially along the horizontal direction, and is provided for each of the hot air furnaces 2, 3, and 4. One end of each hot air outlet pipe 12 is connected to the mixing chamber 23 (see FIG. 2) of each hot air furnace 2, 3, 4, and is connected to the combustion chamber 21 via the mixing chamber 23. Thus, hot air from the heat storage chamber 22 can be introduced into the hot air outlet pipe 12 through the combustion chamber 21 and the mixing chamber 23. Each hot air outlet pipe 12 is detachably provided with a hot air valve 121 for opening and closing the flow path in the pipe.
The hot air main pipe 13 is formed in a tubular shape extending substantially along the horizontal direction, and the other end of each hot air outlet pipe 12 is connected. Further, one end of the hot air main pipe 13 is connected to the annular pipe 14, whereby hot air introduced from each hot air outlet pipe 12 is supplied to the annular pipe 14. Such a hot air main pipe 13 includes a bleeder 131 capable of sucking a gas in the pipe flow path and releasing it to the outside, and a bleeder valve 132 for controlling the flow of the gas to the bleeder 131.
The annular tube 14 is provided so as to surround the outer periphery of the furnace body portion of the blast furnace 5, and is connected to a plurality of tuyere (not shown) of the blast furnace 5. As a result, the hot air introduced from the hot air main pipe 13 can be supplied to the tuyere of the blast furnace 5.

(1-2) Configuration of Hot Air Furnace Next, the configuration of the hot air furnaces 2, 3 and 4 will be described mainly based on FIG. FIG. 2 is a schematic diagram showing one hot stove in the present embodiment.
In FIG. 2, the hot stove 2, 3, 4 is an external combustion type hot stove, and includes an independent combustion chamber 21, a heat storage chamber 22, and a mixing chamber 23.

The combustion chamber 21 includes a main body portion 211 formed in a substantially bottomed cylindrical shape, and a dome portion 212 provided in a state of closing the upper end of the main body portion 211, and is substantially along the vertical direction. Standing in the state.
A ceramic burner 213 is provided at the bottom of the main body 211 in the combustion chamber 21, and the combustion gas supply means 6 and the air supply means 7 are connected thereto. Thereby, the combustion gas and air supplied from the combustion gas supply means 6 and the air supply means 7 are combusted by the ceramic burner 213, and high temperature gas is generated inside the combustion chamber 21.
A manhole 214 is formed at an intermediate position of the main body 211, and a temporary burner 215 (see FIG. 3) is inserted into the combustion chamber 21 through the manhole 214 at the time of heat retention to be described later. It has become so.

The heat storage chamber 22 includes a main body portion 221 formed in a substantially bottomed cylindrical shape, and a dome portion 222 provided so as to close the upper end of the main body portion 221, and is substantially along the vertical direction. Standing in the state.
The inside of the dome portion 222 of the heat storage chamber 22 is connected to the inside of the dome portion 212 of the combustion chamber 21 via a connection pipe 223 so that the gas inside the combustion chamber 21 and the heat storage chamber 22 can flow in both directions. Yes.
A checker brick 224 is stacked inside the main body 221 in the heat storage chamber 22. Further, the air blowing means 10 is connected to the bottom of the main body portion 221 via the air blowing tube 225. The blower pipe 225 is provided with a blower valve 226 that controls the flow of air from the blower 10. In addition, as described above, one end of the flue pipe 8 is connected to the bottom of the main body 221.
In such a heat storage chamber 22, during the combustion period, the heat of the high-temperature gas generated in the combustion chamber 21 is stored in the checker brick 224, the flue valve 81 is opened, and the exhaust gas after combustion becomes the flue pipe 8. It has come to be discharged more. Further, during the blowing period, the blowing valve 226 is opened and air is supplied from the blowing means 10 into the heat storage chamber 22, and the air is heated by the heat stored in the checker brick 224, and thereby the blast furnace 5 side. Hot air to be supplied to is formed.

The mixing chamber 23 includes a main body portion 231 formed in a substantially bottomed cylindrical shape, and a dome portion 232 provided so as to close the upper end of the main body portion 231, and is substantially along the vertical direction. Standing in the state.
One end of a connecting pipe 233 formed in a tubular shape extending substantially along the horizontal direction is connected to the dome part 232 of the mixing chamber 23, and the other end of the connecting pipe 233 is connected to the main body part 211 in the combustion chamber 21. Connected to the middle part. Thereby, the gas inside the combustion chamber 21 and the mixing chamber 23 can flow in both directions. The connection pipe 233 corresponds to a part of the hot air duct in the present invention.
In addition, a cold air supply means 235 is connected to the dome portion 232 of the mixing chamber 23 via a connecting pipe 234. The connection pipe 234 is provided with a cold air valve 236. By adjusting the opening degree of the cold air valve 236, a predetermined amount of cooling air from the cold air supply means 235 is supplied into the mixing chamber 23. ing.
In such a mixing chamber 23, the cooling air from the cold air supply means 235 is mixed with the hot air introduced into the mixing chamber 23 from the heat storage chamber 22 through the combustion chamber 21, and the temperature of the hot air is kept at a constant temperature. It is possible to adjust to. In addition, since the hot air at the initial stage of air blowing is considerably higher than that at the end of the air blowing, the hot air at this time is taken out from the combustion chamber 21 and then mixed with cooling air to be cooled. It is necessary to always adjust the temperature of the hot air blown to the air.

(1-3) Operation Operation of Hot Air Supply System The operation operation of the hot air supply system 1 configured as described above will be described with reference to FIGS. 1 and 2.
The supply of hot air to the blast furnace 5 by the hot air supply system 1 is operated by alternately switching between combustion and air blowing every 40 to 60 minutes in each of the hot air furnaces 2, 3, and 4.
Here, as a specific example, a case will be described in which the combustion process is performed in the hot stoves 2 and 3 in FIG. 1 and the blowing process is performed in the other hot stove 4.

When the combustion process is performed in the hot air furnaces 2 and 3, the hot air valve 121 is closed so that the high-temperature gas generated by the combustion in the combustion chamber 21 does not flow to the hot air main pipe 13. Further, the bleeder valve 132 and the blower valve 226 are closed, and the flue valve 81 is opened.
On the other hand, when the air blowing process is performed in the hot air furnace 4, the hot air valve 121 is opened, and hot air from the heat storage chamber can flow to the hot air main pipe 13 through the combustion chamber 21, the mixing chamber and the hot air outlet pipe 12. Keep it in a proper state. The blower valve 226 is opened, and the bleeder valve 132 and the flue valve 81 are closed.

  Each valve is set in the above state, and the following operation is performed for a predetermined time in the combustion stroke by the hot stove 2 and 3. First, combustion gas and air are supplied from the combustion gas supply means 6 and the air supply means 7 to the combustion chambers 21 of the hot stove 2 and 3, and the combustion gas is burned by the ceramic burner 213 to generate a high temperature gas. Thereafter, the high-temperature gas flows into the heat storage chamber 22 through the connection pipe 223 and passes through the checker brick 224. At this time, the heat of the high-temperature gas is stored in the checker brick 224. The high-temperature gas after passing through the checker brick 224 becomes exhaust gas and is discharged to the outside through the flue pipe 8 and the chimney 9.

  Moreover, in the ventilation process by the hot stove 4, the following operation | movement is implemented for predetermined time in parallel with the said combustion process. First, air is sent from the blowing means 10 into the heat storage chamber 22 of the hot stove 4 through the blower pipe 225. The air passes through the checker brick 224, and at this time, the air is heated by the heat stored in the checker brick 224 to form hot air. This hot air is introduced into the combustion chamber 21 via the connection pipe 223 and further introduced into the mixing chamber 23 via the connection pipe 233. In the mixing chamber 23, a predetermined amount of cooling air from the cold air supply means 235 is mixed with the hot air to adjust the temperature of the hot air to a predetermined temperature. The adjusted hot air flows through the hot air outlet pipe 12 to the hot air main pipe 13 and is further introduced into the annular pipe 14. And the hot air in the annular pipe 14 is introduced into a plurality of tuyere, and pig iron is generated in the blast furnace using this hot air.

(1-4) Method of shutting off heat when repairing a hot air duct In the hot air supply system 1 configured as described above, hot air when repairing the hot air duct 11 is also performed when the furnace body of the blast furnace 5 is repaired. A heat blocking method for the pipe 11 will be described with reference to the drawings.
In the initial state, the blast furnace 5 and the hot blast furnaces 2, 3, and 4 are in a state immediately after the operation is stopped, and both are in a high temperature state.

In this embodiment, from this initial state, the inside of the hot air outlet pipe 12 or the connecting pipe 233 corresponding to the predetermined hot air furnaces 2, 3, 4 is thermally shut off.
That is, the following preparatory process, draft flow path securing process, partition short tube mounting process, heat treatment process, draft wind forming process, breathable member installation process, and fire wall construction process are performed. Here, FIG. 3 is a schematic diagram for explaining the method for shutting off the hot air duct in the first embodiment, (A) shows a preparation step and a draft channel securing step, and (B) is a repair. (C) shows the draft wind formation process, the breathable member installation process, and the fire wall construction process of the hot stove requiring repair.

(1-4-1) Preparatory Step In the preparatory step (FIG. 3A), preparation for carrying out the cooling of the furnace body part of the blast furnace 5 and the heat treatment step is performed.
Cooling the furnace body part of the blast furnace 5 is performed by injecting water into the furnace body part of the blast furnace 5, and water injection is continued for a predetermined time.
As shown in FIG. 3A, preparation for carrying out the heat treatment step is performed by opening the manhole 214 of the combustion chamber 21 and installing a temporary burner 215 inside the combustion chamber 21. Alternatively, the combustion gas and air can be supplied from the combustion gas supply means 6 and the air supply means 7 so that the combustion gas can be burned by the ceramic burner 213.

(1-4-2) Draft Channel Securing Process In the draft channel securing process (FIG. 3A), in order to prevent hot air from being blown when the hot air valve 121 is removed, a draft of two paths is used. Reserve a wind passage.
Specifically, the bleeder valve 132 is opened with the hot air valve 121 closed in order to secure the first draft air flow path. Accordingly, a draft air flow path from the hot air outlet pipe 12 to the bleeder 131 through the hot air main pipe 13 and from the annular pipe 14 to the bleeder 131 through the hot air main pipe 13 is secured. For this reason, when the hot air valve 121 is removed, it is possible to prevent hot air from being ejected from the hot air main pipe 13 side. In this state, the heat in the hot air main pipe 13 and the annular pipe 14 is radiated to the outside through the bleeder 131, and the hot air main pipe 13 and the annular pipe 14 are cooled.
Further, in order to secure the second draft air flow path, the flue valve 81 is opened with the hot air valve 121 and the blower valve 226 closed. Thereby, the draft-like flow path which distribute | circulates the hot air outlet pipe 12, the mixing chamber 23, the combustion chamber 21, the thermal storage chamber 22, the flue pipe 8, and the chimney 9 in order is ensured. For this reason, when the hot air valve 121 is removed, hot air can be prevented from being ejected from the mixing chamber 23 side.
During the draft channel securing step, the cooling of the furnace body portion of the blast furnace 5 is continued.

(1-4-3) Hot-blast furnace partition short pipe installation process that does not require repair In the partition short pipe installation process (Fig. 3 (B)), it is confirmed that the above two paths of draft air flow paths are secured. After that, the hot air valve 121 corresponding to the hot air furnace which does not require repair is removed, and a partition short tube 15 is attached instead.
Here, since it takes a long time to cool the hot air main pipe 13 and the annular pipe 14 in the draft flow path securing step, in order to prevent a temperature drop of the hot air furnaces 2, 3, and 4 during the cooling period, The next heat treatment step is performed simultaneously. Although the temperature reduction of the hot air furnaces 2, 3, 4 can be prevented by this heat treatment step, the hot air valve 121 has insufficient sealing properties, so that the heat from the hot air furnaces 2, 3, 4 passes through the hot air valve 121. It is transmitted to the hot air main pipe 13 side during cooling. For this reason, the cooling efficiency on the hot air main pipe 13 side is lowered. Here, by attaching the partition short pipe 15 and thermally shutting off the mixing chamber 23 side and the hot air main pipe 13 side in the hot air outlet pipe 12, it is possible to prevent a decrease in cooling efficiency on the hot air main pipe 13 side.
In addition, during this partitioning short tube attachment process, the next heat retention process is not implemented.

A specific example of such a short partition 15 is shown in FIG. In FIG. 4, the short partition tube 15 includes a cylindrical main body portion 151, an inner holding portion 152, a heat insulating material 153, and an outer holding portion 154.
The main body 151 has an axial length that is substantially equal to the axial length of the hot air valve 121 and is set to be approximately equal to the diameter of the hot air outlet pipe 12. A flange portion 155 that protrudes outward is formed at the end portion of the main body 151 in the hot stove side, and can be connected to the flange portion 122 of the hot air outlet pipe 12 on the hot stove side.
The inner holding portion 152 is provided on the hot stove side of the main body 151 and is formed of a steel plate having a thickness of about several millimeters in a disk shape that is substantially the same shape as the inner circumference of the main body 151. The inner holding part 152 is located on the inner side of the main body part 151 by about several tens of mm from both axial ends of the main body part 151, and is fixed to the inner peripheral surface of the main body part 151 by welding or the like.
The heat insulating material 153 is formed in a substantially disk shape with a thickness of about several tens of mm using ceramic fiber or the like, and is attached on the end face of the inner holding portion 152 on the hot stove side. With this heat insulating material 153, heat transfer between both ends of the partition short tube 15 is surely prevented.
The outer holding portion 154 is provided at a blast furnace (hot air main) side end portion of the main body portion 151 and is formed in a disk shape having a larger diameter than the main body portion 151. A flange portion 155 that can be connected to the flange portion 122 on the blast furnace side of the hot air outlet pipe 12 is provided on the outer peripheral edge portion of the outer holding portion 154, and the partition short pipe 15 is attached to the hot air outlet pipe 12. It is supposed to be. A space is formed between the outer holding portion 154 and the inner holding portion 152, so that heat transfer between both ends of the short partition tube 15 is more reliably prevented.

(1-4-4) Heat Treatment Step In the heat treatment step (FIG. 3B), while the cooling of the hot air main pipe 13 and the annular pipe 14 and the cooling of the blast furnace 5 are continued, the temporary burner 215 or the ceramic burner 213 is used. Then, the combustion gas is burned, and the heat treatment of the hot stoves 2, 3 and 4 is started. Thereby, it is possible to prevent the temperature of the hot air furnaces 2, 3, 4 from being lowered during the cooling period of the hot air main pipe 13 and the like, and to prevent damage to the dome portions 212, 222 (see FIG. 2) caused by the temperature drop. it can.

(1-4-5) Draft wind forming process of hot air furnace requiring repair In the draft air forming process (FIG. 3C), the draft air is circulated and the hot air outlet pipe 12 corresponding to the hot air furnace requiring repair is installed. The mixing chamber 23 side and the inside of the connecting pipe 233 are cooled.
Specifically, the hot air valve 121 corresponding to the hot air furnace requiring repair is removed. Thereby, an opening part is formed in the hot air outlet pipe 12, and the outside air flows into the mixing chamber 23 side of the hot air outlet pipe 12 through the opening part. And the said external air turns into the draft wind which distribute | circulates the mixing chamber 23, the combustion chamber 21, the heat storage chamber 22, the flue pipe | tube 8, and the chimney 9 in order from the said opening part of the hot air outlet pipe | tube 12, The mixing chamber 23 side and the inside of the connecting pipe 233 are cooled.

After removing the hot air valve 121 as described above, the opening degree of the flue valve 81 is further increased, and the cooling capacity is increased by increasing the flow rate of the draft air. Then, the cooling is continued until the ambient temperature at the heat cutoff scheduled position becomes, for example, 50 ° C. or lower.
For example, when the repair planned portion is set on the mixing chamber 23 side in the hot air outlet pipe 12, the heat cutoff scheduled position is downstream of the draft wind from the repair planned portion, that is, for example, in the hot air outlet pipe 12. Is set at any position in the end of the mixing chamber 23 or in the connecting pipe 233. Further, for example, when a repair planned part is set in the connection pipe 233, it is set on the downstream side of the draft wind from the repair planned part, that is, for example, at the end of the connection pipe 233 on the combustion chamber 21 side.

In such a draft wind formation process, the draft wind also circulates inside the combustion chamber 21 and the heat storage chamber 22, but the cooling rate by the draft wind is higher in the hot air outlet pipe 12 and the connection pipe 233 than in the combustion chamber 21 and the heat storage. It is much larger than room 22. For this reason, the temperature in the hot air outlet pipe 12 and the connection pipe 233 can be lowered to, for example, 50 ° C. or less while the internal temperatures of the combustion chamber 21 and the heat storage chamber 22 are not greatly reduced. Therefore, the high temperature state of the combustion chamber 21 and the heat storage chamber 22 can be maintained, and damage caused by the temperature drop of the dome portions 212 and 222 can be prevented.
Although the decrease rate of the internal temperature of the combustion chamber 21 and the heat storage chamber 22 is small as described above, the temperature decrease surely proceeds by continuing the draft air flow. For this reason, the temperature of the dome parts 212 and 222 must be sufficiently increased in consideration of the minimum required dome temperature (for example, about 1200 ° C.) + The temperature drop + the margin.
Further, the cooling rate (cooling capacity) by the draft air is related to the opening degree of the flue valve 81, and the cooling rate is improved by increasing the opening degree. However, if the cooling rate is increased too much, the temperature drop rate of the dome portions 212 and 222 is increased before the blowing of the hot stove is stopped, and the dome portions 212 and 222 are damaged or collapsed. For this reason, it is necessary to adjust the opening degree of the flue valve 81 in consideration of the temperature of the dome portions 212 and 222 so that the cooling rate by the draft air does not exceed a predetermined rate.

(1-4-6) Breathable Member Installation Step Next, the breathable member installation step will be described mainly based on FIG. 3 (C) and FIG. Drawing 5 is a mimetic diagram for explaining a breathable member installation process and a fireproof wall construction process.
In the breathable member installation step, as shown in FIG. 3C and FIG. 5, the breathable member 16 is transported to the mixing chamber 23 side in the hot air outlet pipe 12 or the heat cutoff scheduled position in the connection pipe 233, The breathable member 16 is erected at the heat cutoff scheduled position.

Specifically, as shown in FIG. 5, when the temperature at the heat cutoff scheduled position becomes 50 ° C. or less, a heat insulating member 17 such as a ceramic fiber sheet is laid on the lower surface in the tube to take measures against heat insulation at the feet. Then, the worker wearing the cool suit holds the breathable member 16 and enters the mixing chamber 23 side from the opening provided in the hot air outlet pipe 12. Further, the worker carries the breathable member 16 along the draft flow direction (arrow A in FIG. 5) to the heat cutoff scheduled position.
Here, when the heat shut-off scheduled position is set in the connection pipe 233, after temporarily placing a scaffold in which the operator can move in the mixing chamber 23, the breathable member 16 is always positioned downstream of the operator's draft wind. In this state, it is carried to the heat cutoff scheduled position in the connecting pipe 233. In addition, when the heat shield scheduled position is set on the mixing chamber 23 side in the hot air outlet pipe 12, it is not necessary to temporarily install such a scaffold.
Further, during transportation, one end of the wire 166 (see FIG. 9) continuous from the opening of the hot air outlet pipe 12 is attached to the upper part of the outer peripheral portion of the air-permeable member 16, and the other end of the wire 166 is pulled from the opening side. Therefore, it is preferable that the air-permeable member 16 does not fall down due to a draft or the like.

When the air-permeable member 16 is carried in in this way, the mixing chamber 23 side, the mixing chamber 23 or the connection pipe 233 in the hot air outlet pipe 12 is sufficiently cooled, and is being carried in from the combustion chamber 21 side. Hot air does not flow toward the workers. However, from the combustion chamber 21 side, as indicated by an arrow B in FIG.
In this respect, since the radiant heat can be blocked by the air-permeable member 16, it is possible to prevent a worker who is carried in from being exposed to the radiant heat. In addition, since draft air can pass through the air-permeable member 16, distribution of the draft air is not hindered. Therefore, it is possible to ensure the safety of the worker at the time of carrying in.

Here, a specific example of the above-described air-permeable member 16 is shown in FIGS.
6A and 6B, the air-permeable member 16 includes a pair of frames 161 facing each other, two metal meshes 162, a connecting portion 163, a parallel portion 164, and a gripping portion 165. Yes.
The pair of frames 161 are each formed in an annular shape smaller than the cross section in the direction perpendicular to the axis of the hot air outlet pipe 12 and the connecting pipe 233, and are provided so as to face each other.
The two metal meshes 162 are each formed of a metal material such as a SUS material, and those having 50 to 200 mesh are used. Since such a wire mesh 162 is attached to each frame 161 so as to close the inside of each frame 161, the wire mesh 162 is formed in a planar circle shape smaller than the cross section in the direction perpendicular to the axis of the hot air outlet pipe 12 and the like.
The connecting portion 163 is a plurality of rod members having a length of 30 to 100 mm, and connects the frames 161 to each other. The connecting portion 163 defines the interval between the frames 161, and the two metal meshes 162 face each other with a predetermined interval.
The parallel portion 164 is two rod members attached to one frame 161 of the pair of frames 161 and is provided in a state parallel to each other in the plane of the one frame 161.
The grip portion 165 is a rod member that is bent in a substantially U shape and protrudes in the out-of-plane direction of one frame 161, and is attached to the pair of parallel portions 164 in a bridging manner.

  The air-permeable member 16 is transported while an operator grips the grip portion 165 and maintains it in a state substantially orthogonal to the axial direction of the hot air outlet pipe 12 and the like. At this time, since the mesh of the wire mesh 162 and the interval between the wire meshes 162 are adjusted under the above conditions, the radiant heat from the combustion chamber 21 side and the like can be surely cut off, and the draft wind can pass well. be able to. Moreover, since the metal mesh 162 is a lightweight member and the grip part 165 is also provided, the operator can easily transport the breathable member 16. Furthermore, since the wire mesh 162 is formed in a plane circle shape smaller than the cross section in the direction perpendicular to the axis of the hot air outlet pipe 12 and the like, the air-permeable member 16 has good transportability and work efficiency can be improved. In addition, since the air-permeable member 16 has a simple configuration and an inexpensive material can be used, the manufacturing cost of the air-permeable member 16 can be reduced.

The breathable member 16 is not limited to the one provided with the wire mesh 162 as shown in FIG. 6, and may be one using a breathable solid.
That is, although not specifically shown, the breathable solid is formed in a substantially disk shape and has a plurality of through holes substantially along the thickness direction. When the air-permeable solid is thinly formed, the air-permeable member 16 can be configured by attaching to the pair of frames 161 instead of the two metal meshes 162 shown in FIG. In addition, when the air-permeable solid is formed thick, the air-permeable member 16 can be configured by attaching an annular frame to the outer periphery of the air-permeable solid and further providing a grip portion on the frame.
Such a breathable solid can have any structure as long as it has a plurality of through holes. A honeycomb structure, a structure in which a large number of wires are bundled to form an axial passage between the wires, a small-diameter pipe is used. Examples of a large number of axial passages that are assembled together, a structure in which corrugated sheets and flat plates are alternately stacked, and a structure in which corrugated sheets and flat plates are stacked and wound in a roll shape can be exemplified. Moreover, the material should just have heat resistance and impact resistance, and a ceramic, a metal, etc. are mentioned.
Even when such a breathable solid is used for the breathable member 16, it is possible to achieve substantially the same effect as the breathable member 16 shown in FIG. 6.

After carrying in the above-mentioned air-permeable member 16 to the heat shut-off scheduled position, the air-permeable member 16 is erected at the heat shut-off scheduled position in a state substantially orthogonal to the axial direction of the hot air outlet pipe 12 and the like.
There is no particular limitation on the method of erecting such a breathable member 16. For example, the wedge can be erected by being sandwiched between the outer peripheral portion of the air-permeable member 16 and the inner wall of the pipe line. Further, for example, it can be erected by pulling the upper side of the outer peripheral portion of the breathable member 16 with a wire or the like. Moreover, if it is the structure which has thickness like the air permeable member 16 of FIG. 6, it can also stand upright as it is.
Thereby, the worker can be protected from radiant heat even while the fire wall is constructed in the fire wall construction process in the subsequent process. Moreover, since it is the structure which conveys the air permeable member 16 after ensuring the safety | security of an operator as mentioned above, the heat cutoff scheduled position is set to the arbitrary positions in the hot air outlet pipe 12 and the connection pipe 233. it can.

(1-4-7) Fire wall construction process In the fire wall construction process (FIG. 3 (C)), a plurality of fire bricks are placed at positions adjacent to the installed breathable member 16 (two-dot chain line C in FIG. 5). A fireproof wall is constructed in a state in which the inside of the hot air outlet pipe 12 and the like is closed.
Specifically, for example, when an operator carries in the air-permeable member 16 in the air-permeable member installation step in the previous step, a different worker positions a plurality of refractory bricks adjacent to the air-permeable member 16 after that. Transport to (two-dot chain line C in FIG. 5). Then, a plurality of refractory bricks are stacked at the position, and mortar is applied to the refractory bricks, thereby constructing a refractory wall substantially along the vertical direction.

Accordingly, any position in the hot air outlet pipe 12 or any position in the connection pipe 233 can be closed, and the fireproof wall and the breathable member 16 installed in the breathable member installation process Thus, the heat cutoff scheduled position in the hot air outlet pipe 12 or the like can be reliably cut off. Therefore, when a fire wall or the like is installed in the hot air outlet pipe 12, the outlet side can be set as a repair range with respect to the fire wall or the like in the hot air outlet pipe 12. Further, when a fire wall or the like is installed in the connection pipe 233, the entire range in the connection pipe 233 on the side of the mixing chamber 23, in the mixing chamber 23, and in the hot air outlet pipe 12 can be set as the repair range.
With the above, the heat insulation work is completed. In such a heat insulation work, the cooling time in the hot air duct 11 by the draft air and the installation time of the air-permeable member 16 and the fireproof wall can be shortened, so that a series of heat insulation work can be completed quickly.

(1-5) Examples In order to confirm the effect of the first embodiment, the following heat cutoff experiment was conducted in an actual furnace.
■ Repair time: At the time of refurbishing the furnace section of the blast furnace 5 ■ Scheduled heat shutoff position: in the hot air outlet pipe 12 ■ Minimum required dome temperature: 950 ° C for both dome parts 212 and 222
■ Checker metal receiving temperature: 350 ° C. or less ■ Hot stove operation stop condition: After performing the heat treatment process in substantially the same manner as the heat shut-off method described in (1-4) above, finally 4: 20 ~ The combustion was stopped at 5 o'clock and the flue valve 81 was closed.
(2) Heat shut-off experiment: After stopping the combustion, the draft wind forming step, the breathable member installing step, and the fire wall construction step were performed in the same manner as the heat shut-off method described in (1-4) above. The temperature in the dome portion 212 of the combustion chamber 21, the dome portion 222 of the heat storage chamber 22, the checkered metal received, and the hot air outlet pipe 12 was measured every predetermined time. Table 1 shows the opening of the flue valve 81 at each time, the temperature of each part, and the work content. Moreover, the graph which plotted the temperature of the dome parts 212 and 222 in each time in FIG. 7 is shown.

As shown in Table 1, the flue valve 81 was opened 200 mm at 8:30 (the same purpose as the draft channel securing step). At 9:02, the removal of the partition short tube 15 was started (start of the draft wind forming process). At 10:28, the opening of the flue valve 81 was increased to 500 mm.
At 10:37, the temperature of the hot air outlet pipe 12 became 50 ° C. or lower, so that the opening of the flue valve 81 was further increased to 800 mm and the carry-in of the air-permeable member 16 was started (in the air-permeable member installation process). start).
At this time, the dome part 212 of the combustion chamber 21 is cooled by about 113 ° C., the dome part 222 of the heat storage chamber 22 is cooled by about 79 ° C., and the hot air outlet pipe 12 is about The temperature was 480 ° C. (see FIG. 7). From this, it can be seen that the cooling rate of the hot air outlet pipe 12 is 4 to 6 times larger than the cooling rates of the combustion chamber 21 and the heat storage chamber 22. It was also found that the breathable member installation process can be started in about one and a half hours from the start of the draft wind forming process.

Immediately after the breathable member 16 was carried in, the refractory brick was carried in (start of the refractory wall construction process). At 11:00, the construction of the half of the fire wall was completed, and at 11:17, the construction of the fire wall was completed (completion of the heat shielding work).
At the time of completion, the dome portion 212 of the combustion chamber 21 was lowered by about 107 ° C. and the dome portion 222 of the heat storage chamber 22 was lowered by about 81 ° C. (see FIG. 7). ). These lowering temperatures were almost equal to the lowering temperature at the start of the breathable member installation process, and it was found that the combustion chamber 21 and the heat storage chamber 22 hardly dropped in the breathable member installation process and the fire wall construction process.
At the time of completion, the dome portion 212 of the combustion chamber 21 was 993 ° C., and the dome portion 222 of the heat storage chamber 22 was 1091 ° C. Accordingly, it was found that the temperature of the dome portions 212 and 222 does not fall below the minimum required dome temperature even if the draft air flow is continued in a series of heat shielding operations.
As mentioned above, according to this method, it turned out that a series of heat insulation work can be completed in about two and a half hours. In addition, the operator's safety was sufficiently ensured through the above work, and the repair work in the hot air outlet pipe 12 after the heat shielding work could be performed well.

(2) Second Embodiment Next, a second embodiment of the present invention will be described based on the drawings.
In the present embodiment, the hot air duct is repaired during the wind-off period, and is different from the first embodiment only in the repair operation shown in (1-4) above. For this reason, below, description is abbreviate | omitted suitably about the structure similar to said 1st embodiment.
In the initial state, the blast furnace 5 is in a resting state, and the predetermined hot air furnaces 2, 3, and 4 are in a state immediately after the air blowing is stopped, both of which are in a high temperature state.

In this embodiment, from this initial state, the inside of the hot air outlet pipe 12 or the connecting pipe 233 corresponding to the predetermined hot stove 2, 3, 4 is thermally shut off.
That is, a preparation process, a draft flow path securing process, a draft wind forming process, a breathable member installation process, a fire wall construction process, and a heat treatment process are performed as described below. Here, FIG. 8 is a schematic diagram for explaining a method for shutting off the hot air duct in the second embodiment, (A) shows a preparation process, a draft flow path securing process and a draft wind forming process, (B) shows a breathable member installation process and a fire wall construction process, and (C) shows a heat treatment process.

(2-1) Preparation Step In the preparation step (FIG. 8 (A)), preparations for carrying out the heat treatment step are performed.
Specifically, as shown in FIG. 8 (A), the manhole 214 of the combustion chamber 21 is opened and a temporary burner 215 is installed inside the combustion chamber 21. Alternatively, the combustion gas and air can be supplied from the combustion gas supply means 6 and the air supply means 7 so that the combustion gas can be burned by the ceramic burner 213.

(2-2) Draft channel securing step In the draft channel securing step (FIG. 8A), in order to prevent hot air from being ejected when the hot air valve 121 is removed in the draft air forming step of the next step. The draft path of two paths is secured.
Specifically, the bleeder valve 132 is opened with the hot air valve 121 closed in order to secure the first draft air flow path. Accordingly, a draft air flow path from the hot air outlet pipe 12 to the bleeder 131 through the hot air main pipe 13 and from the annular pipe 14 to the bleeder 131 through the hot air main pipe 13 is secured. For this reason, when the hot air valve 121 is removed, it is possible to prevent hot air from being ejected from the hot air main pipe 13 side.
Further, in order to secure the second draft air flow path, the flue valve 81 is opened with the hot air valve 121 and the blower valve 226 closed. Thereby, the draft-like flow path which distribute | circulates the hot air outlet pipe 12, the mixing chamber 23, the combustion chamber 21, the thermal storage chamber 22, the flue pipe 8, and the chimney 9 in order is ensured. For this reason, when the hot air valve 121 is removed, hot air can be prevented from being ejected from the mixing chamber 23 side.

(2-3) Draft Air Formation Step In the draft air formation step (FIG. 8A), the draft air is circulated to cool the inside of the connecting tube 233 and the hot air outlet tube 12 side.
Specifically, the hot air valve 121 is removed after confirming that the draft path of the two paths is secured. Thereby, an opening is formed in the hot air outlet pipe 12. At this time, the heat insulating plate 18 is quickly attached to the hot air main pipe 13 side in the opening.

Here, the heat insulating plate 18 is attached for the purpose of preventing outside air from flowing into the hot air main pipe 13 through the opening. Further, the heat insulating plate 18 is configured such that when air is blown to the blast furnace 5 by a hot blast furnace other than the hot blast furnace to be repaired after the heat blocking operation, the hot blast from the other hot blast furnace is heated. Blowing out from the opening of the outlet pipe 12 is prevented.
A specific example of such a heat insulating plate 18 is shown in FIG. In FIG. 9, the heat insulating plate 18 includes a heat insulating material 181 and a holding portion 182.
The heat insulating material 181 is formed, for example, in a disk shape having a thickness of about 50 mm using ceramic fiber or the like, and is provided in a state where it can be inserted into the hot air main pipe side of the hot air outlet pipe 12.
The holding portion 182 is formed in a disk shape having a thickness of about 6 mm with a steel plate or the like, and is fixed to the flange portion 122 on the hot air main pipe side of the hot air outlet pipe 12. A heat insulating material 181 is attached to the blast furnace side end face of the holding portion 182.

Then, by removing the hot air valve 121 and forming an opening in the hot air outlet pipe 12, the outside air flows into the mixing chamber 23 side of the hot air outlet pipe 12 through the opening. And the said external air turns into the draft wind which distribute | circulates the mixing chamber 23, the combustion chamber 21, the heat storage chamber 22, the flue pipe | tube 8, and the chimney 9 in order from the said opening part of the hot air outlet pipe | tube 12, The mixing chamber 23 side and the inside of the connecting pipe 233 are cooled.
After the heat insulating plate 18 is attached, the opening of the flue valve 81 is further increased, and the cooling capacity is increased by increasing the flow rate of the draft air. Then, the cooling is continued until the ambient temperature at the heat cutoff scheduled position becomes, for example, 50 ° C. or lower.

  In such a draft wind formation process, although the draft wind circulates inside the combustion chamber 21 and the heat storage chamber 22, as in the first embodiment, the high temperature state of the combustion chamber 21 and the heat storage chamber 22 can be maintained, and the dome is maintained. The damage etc. resulting from the temperature fall of the parts 212 and 222 can be prevented. The temperature of the dome portions 212 and 222 must be sufficiently increased in consideration of the minimum required dome temperature (for example, about 1200 ° C.) + The temperature drop + the margin as in the first embodiment. . The opening degree of the flue valve 81 needs to be adjusted in consideration of the temperature of the dome portions 212 and 222 as in the first embodiment.

(2-4) Breathable member installation process In the breathable member installation process (FIG. 8B), the breathable member 16 is moved to the mixing chamber 23 side in the hot air outlet pipe 12 or to the heat cutoff scheduled position in the connection pipe 233. The air-permeable member 16 is erected at the planned heat shielding position.
Specifically, as shown in FIG. 9, when the temperature at the heat cutoff scheduled position becomes 50 ° C. or lower, a heat insulating member 17 such as a ceramic fiber sheet is laid on the lower surface in the pipe to take measures against heat insulation at the feet. Then, the worker wearing the cool suit holds the breathable member 16 and enters the mixing chamber 23 side from the opening provided in the hot air outlet pipe 12. Further, the worker carries the air-permeable member 16 along the draft airflow direction to the heat cutoff scheduled position.

Here, when the heat shut-off scheduled position is set in the connection pipe 233, after temporarily placing a scaffold in which the operator can move in the mixing chamber 23, the breathable member 16 is always positioned downstream of the operator's draft wind. In this state, it is carried to the heat cutoff scheduled position in the connecting pipe 233. In addition, when the heat shield scheduled position is set on the mixing chamber 23 side in the hot air outlet pipe 12, it is not necessary to temporarily install such a scaffold.
Further, during transportation, one end of the wire 166 continuous from the opening of the hot air outlet pipe 12 is attached to the upper part of the outer peripheral portion of the breathable member 16, and the other end of the wire 166 is pulled from the opening side, whereby the breathable member It is preferable that 16 does not fall down due to a draft or the like.

The air permeable member 16 used is the same as the air permeable member 16 of the first embodiment shown in (1-4-6) above. For this reason, also in this embodiment, there can exist an effect similar to the air permeable member 16 shown to said (1-4-6).
After carrying the breathable member 16 to the planned heat shutoff position, the breathable member 16 is set up in a state substantially orthogonal to the axial direction of the hot air outlet pipe 12 and the like at the planned heat shutoff position, as in the first embodiment. Set up.

(2-5) Fire wall construction process In the fire wall construction process (FIG. 8B), a plurality of fire bricks are used at positions adjacent to the installed breathable member 16 (two-dot chain line C in FIG. 5). The fireproof wall is constructed so as to close the inside of the hot air outlet pipe 12 and the like. The specific operation in the fire wall construction process is the same as that in the fire wall construction process of the first embodiment shown in (1-4-7) above. For this reason, also in this embodiment, there can exist an effect similar to the effect shown to said (1-4-7).
By this fireproof wall construction process, the inside of the hot air outlet pipe 12 and the like can be repaired, and thereafter, the hot air outlet pipe 12 and the like accompanied by brick refilling and the like are repaired.

(2-6) Heat Treatment Process In the heat treatment process (FIG. 8C), after repairing the hot air outlet pipe 12 and the like after the fire wall construction process, the combustion gas is burned by the temporary burner 215 or the ceramic burner 213. Then, the heat treatment of the hot stoves 2, 3 and 4 is started. Thereby, it is possible to prevent the temperature of the hot air furnaces 2, 3, 4 from being lowered during the repair of the hot air outlet pipe 12 and the like, and it is possible to prevent damage to the dome portions 212, 222 (see FIG. 2) and the like due to the temperature drop. . This heat treatment is continuously performed until the repair of the hot air outlet pipe 12 and the like is completed.
In addition, after the above-described refractory wall construction process, air blowing to the blast furnace 5 is started by a hot blast furnace other than the hot blast furnace to be repaired, and the operation of the blast furnace 5 is resumed.

(3) Third Embodiment Next, a third embodiment of the present invention will be described based on the drawings.
In the third embodiment, the hot air duct in the hot air supply system equipped with the internal combustion hot stove is repaired at the time of refurbishing the furnace body part of the blast furnace as in the first embodiment. As in the second embodiment, the operation is performed during the wind-off period. Therefore, in the following, the configuration of the hot air furnace will be mainly described, and the operation operation of the hot air supply system and the repair operation of the hot air duct are the same as those in the first or second embodiment, so the description will be simplified. To do.

(3-1) Configuration of Hot Air Furnace FIG. 10 shows one hot air furnace in the present embodiment. In FIG. 10, the hot stove 2 </ b> A, 3 </ b> A, 4 </ b> A is an internal combustion hot stove, and includes a cylindrical structure 24 and a mixing chamber 23. In addition, about the structure of the mixing chamber 23, since it is the structure similar to the mixing chamber 23 in said 1st and 2nd embodiment, description is abbreviate | omitted.

The cylindrical structure 24 includes a main body portion 241 formed in a substantially bottomed cylindrical shape and a dome portion 242 provided in a state of closing the upper end of the main body portion, and is in a state substantially along the vertical direction. Is erected.
Inside the main body 241 is provided a refractory brick wall 243 substantially extending in the vertical direction, and the inside of the main body 241 is partitioned into a combustion chamber 244 and a heat storage chamber 245 by the refractory brick wall 243. The upper portions of the combustion chamber 244 and the heat storage chamber 245 communicate with each other via the internal space of the dome portion 242 so that the gas inside the combustion chamber 244 and the heat storage chamber 245 can flow in both directions.

  At the bottom of the combustion chamber 244, a ceramic burner 246 is provided, and the combustion gas supply means 6 and the air supply means 7 are connected. As a result, the combustion gas and air supplied from the combustion gas supply means 6 and the air supply means 7 are combusted by the ceramic burner 246, and high temperature gas is generated inside the combustion chamber 244.

A checker brick 247 is stacked inside the heat storage chamber 245. In addition, the blowing means 10 is connected to the bottom of the heat storage chamber 245 via a blower pipe 248. The blower pipe 248 is provided with a blower valve 249 that controls the flow of air from the blower 10. In addition, as described above, one end of the flue pipe 8 is connected to the bottom of the heat storage chamber 245.
In such a heat storage chamber 245, in the combustion period, the heat of the high-temperature gas generated in the combustion chamber 244 is stored in the checker brick 247, the flue valve 81 is opened, and the exhaust gas after combustion flows into the flue pipe 8 It has come to be discharged more. Further, during the blowing period, the blowing valve 249 is opened and air is supplied from the blowing means 10 into the heat storage chamber 245, and the air is heated by the heat stored in the checker brick 247, thereby the blast furnace 5 side. Hot air to be supplied to is formed.

  In the hot air supply system 1 (see FIG. 1) provided with the internal combustion type hot air furnaces 2A, 3A, 4A as described above, the supply of hot air to the blast furnace 5 is the same as the operation described in (1-3) above. In each hot stove 2A, 3A, 4A, operation is performed by alternately switching between combustion and blowing every 40 to 60 minutes.

(3-2) Method of shutting off heat during repair of hot air duct In the hot air supply system 1 having the internal combustion hot air furnaces 2A, 3A, 4A as described above, the hot air duct 11 is repaired as described in the first embodiment. It carries out together with the form at the time of repair of the furnace body part of the blast furnace 5 similarly to a form. Or it implements during a rest period like the said 2nd embodiment.
In the former case, in the heat shut-off operation in the hot air outlet pipe 12 or the connecting pipe 233, as in the heat shut-off method shown in (1-4) above, a preparation process, a draft flow path securing process, and a partition short pipe mounting A process, a heat retention process, a draft wind forming process, a breathable member installation process, and a fire wall construction process are performed. As a result, similarly to the first embodiment, any position in the hot air outlet pipe 12 or the connection pipe 233 can be thermally shut off quickly at low cost.
In the latter case, in the heat shut-off work in the hot air outlet pipe 12 or the connection pipe 233, as in the heat shut-off method shown in (2) above, a preparation step, a draft flow path securing step, a draft wind forming step, A breathable member installation process, a fire wall construction process, and a heat treatment process are performed. Thereby, similarly to said 2nd embodiment, the arbitrary positions in the hot-air outlet pipe 12 or the connection pipe 233 can be heat-blocked quickly at low cost.

(4) Modification of Embodiments The present invention is not limited to the above-described embodiments, but includes modifications and improvements as long as the object of the present invention can be achieved.

  In the said embodiment, as a case where repair of the hot blast pipe line 11 is implemented, the case where it implements in combination with the repair of the furnace body part of the blast furnace 5 and the case where it implements during a wind-break period were illustrated, but it is not limited to this Absent. That is, the hot air duct 11 may be repaired, for example, when a large-scale attached facility other than the furnace body of the blast furnace 5 is repaired.

  In the first embodiment, the fire wall construction process is arranged in the final process in the series of heat shut-off operations. However, similarly to the second embodiment, after the fire wall construction process, the heat treatment process is performed again. May be. Thereby, when repairing the hot air duct 11 after the fire wall construction process, the temperature drop of the combustion chamber 21 and the heat storage chamber 22 can be prevented, and the life of the hot air furnaces 2, 3, and 4 can be increased. Can do.

  In the said embodiment, although it was set as the structure which discharges draft wind from the chimney 9 or the bleeder 131, it is not restricted to this. That is, if the cooling by the draft wind is insufficient, or if it is considered that the cooling process takes too much time and the process is affected, the temporary air duct 8, the hot air duct 11, the cold air duct 234, etc. A bleeder or an ejector may be installed.

It is a schematic diagram which shows the hot air supply system in 1st embodiment of this invention. It is a schematic diagram which shows one hot stove in said 1st and 2nd embodiment. It is a schematic diagram for demonstrating the heat | fever interception method of the hot blast pipe line in said 1st embodiment, (A) shows a preparatory process and a draft flow-path ensuring process, (B) is the partition of the hot blast furnace which does not require repair. A short tube attachment process and a heat retention process are shown, and (C) shows a draft wind formation process, a breathable member installation process, and a fire wall construction process for a hot stove requiring repair. It is a sectional side view which shows the partition short tube used at the partition short tube attachment process in said 1st embodiment. It is a schematic diagram for demonstrating the air permeable member installation process and fire wall construction process in said 1st embodiment. An example of the air permeable member in said 1st embodiment is shown, (A) is a top view, (B) is a side view. It is a graph which shows the experimental result in the Example for confirming the effect of said 1st embodiment. It is a schematic diagram for demonstrating the heat | fever interception method of the hot air duct in said 2nd embodiment, (A) shows a preparatory process, a draft flow-path ensuring process, and a draft wind formation process, (B) is an air permeable member. An installation process and a fire wall construction process are shown, and (C) shows a heat treatment process. It is a schematic diagram for demonstrating the draft wind formation process and air permeable member installation process in said 2nd embodiment. It is a schematic diagram which shows one hot stove in said 3rd embodiment.

Explanation of symbols

1 ... Hot air supply system 2, 3, 4 ... Hot air furnace (external combustion type hot air furnace)
21 ... Combustion chamber 211 ... Body portion 212 ... Dome portion 213 ... Ceramic burner 214 ... Manhole 215 ... Temporary burner 22 ... Thermal storage chamber 221 ... Body portion 222 ... Dome portion 223 ... Connection pipe 224 ... Checker brick 225 ... Air blow pipe 226 ... Air blow Valve 23 ... Mixing chamber 231 ... Main body 232 ... Dome part 233 ... Connection pipe 234 ... Connection pipe 235 ... Cold air supply means 236 ... Cold air valves 2A, 3A, 4A ... Hot air furnace (internal combustion hot air furnace)
DESCRIPTION OF SYMBOLS 24 ... Cylindrical structure 241 ... Main-body part 242 ... Dome part 243 ... Refractory brick wall 244 ... Combustion chamber 245 ... Thermal storage chamber 246 ... Ceramic burner 247 ... Checker brick 248 ... Blower pipe 249 ... Blast valve 5 ... Blast furnace 6 ... Combustion gas Supply means 7 ... Air supply means 8 ... Flue pipe 81 ... Flue valve 9 ... Chimney 10 ... Blower means 11 ... Hot air duct 12 ... Hot air outlet pipe 121 ... Hot air valve 122 ... Flange part 13 ... Hot air main pipe 131 ... Breeder 132 ... Breeder valve 14 ... Annular pipe 15 ... Short partition 151 ... Main body 152 ... Inner holding part 153 ... Heat insulating material 154 ... Outer holding part 155 ... Flange part 16 ... Breathable member 161 ... Frame 162 ... Metal mesh 163 ... Connection part 164 ... Parallel part 165 ... Holding part 166 ... Wire 17 ... Heat insulation member 18 ... Thermal insulation plate 181 ... Heat insulation material 182 ... Holding part

Claims (13)

When repairing a hot air duct connecting the hot blast furnace having a combustion chamber and a heat storage chamber and the tuyere of the blast furnace, a method of thermally shutting off the inside of the hot blast duct,
A draft wind forming step for forming a draft wind for providing an opening in the hot air duct and allowing the outside air to flow from the opening to pass through the repair scheduled section in the hot air duct to cool the planned repair section. When,
A breathable member capable of blocking radiant heat is carried along the draft air flow from the opening to a heat cutoff scheduled position on the downstream side of the draft air from the repair planned portion in the hot air duct. , A breathable member installation process to be installed at the heat shielding scheduled position,
A fire wall construction step of constructing a fire wall in a state of closing the inside of the hot air duct using a fire resistant member at a position adjacent to the installed air-permeable member in the hot air duct. This is a heat shut-off method when repairing hot air ducts. In the heat shut-off method at the time of hot air duct repair according to claim 1,
The hot stove is provided as a substantially cylindrical structure in which the combustion chamber and the heat storage chamber are independent from each other, and the external combustion type has a structure in which the dome portions of the combustion chamber and the heat storage chamber are connected to each other by a connecting pipe. This is a heat shut-off method during hot air duct repair, characterized by being a hot air furnace. In the heat shut-off method at the time of hot air duct repair according to claim 1,
The hot air furnace is an internal combustion hot air furnace having a structure in which the inside of one substantially cylindrical structure is partitioned by a refractory brick wall to provide the combustion chamber and the heat storage chamber. This is a heat shut-off method. In the heat insulation method at the time of hot-air duct repair in any one of Claims 1 thru / or 3,
The breathable member is configured with a metal mesh made of a metal material,
The wire mesh is formed in a planar shape smaller than the cross section in the direction perpendicular to the axis of the hot air duct, and is a method for shutting off heat during hot air duct repair. In the heat insulation method at the time of hot air duct repair according to claim 4,
The air-permeable member includes a plurality of the metal meshes, and each of the metal meshes is disposed in a state of being opposed to each other with a predetermined interval. It is. In the heat insulation method at the time of hot-air duct repair of Claim 4 or Claim 5,
The wire mesh is a 50 to 200 mesh one, and is a method for heat insulation during hot air duct repair. In the heat insulation method at the time of hot-air duct repair in any one of Claims 1 thru / or 3,
The breathable member is configured with a breathable solid,
The breathable solid is formed in a flat plate shape smaller than the cross-sectional shape in the axis-perpendicular direction of the hot air duct, and has a plurality of through holes substantially along the thickness direction. Hot air duct repair This is a method for shutting off heat at the time. In the heat insulation method at the time of hot-air duct repair in any one of Claims 1 thru / or 7,
The hot air duct is formed in a tubular shape extending substantially along the horizontal direction, one end is connected to the combustion chamber, and hot air from the heat storage chamber can be introduced into the blast furnace through the combustion chamber. A tube,
In the hot air duct repair, the heat shutoff scheduled position in the breathable member installation step and the fire wall construction step is set in the hot air outlet pipe. In the heat shut-off method at the time of hot air duct repair according to claim 8,
The hot stove is connected to the combustion chamber via a connecting pipe formed in a tubular shape extending substantially along the horizontal direction, and cooling air is mixed with hot air introduced from the heat storage chamber via the combustion chamber. It has a mixing chamber that adjusts the temperature of the hot air,
The one end side of the hot air outlet pipe is connected to the combustion chamber through the mixing chamber, and hot air adjusted in the mixing chamber can be introduced into the blast furnace,
In the hot air duct repair, the heat shutoff scheduled position in the breathable member installation process and the fire wall construction process is set in the hot air outlet pipe or in the connection pipe. In the heat shut-off method at the time of hot air duct repair according to claim 9,
The hot air outlet pipe is detachably provided with a hot air valve that opens and closes the flow path in the pipe,
A flue pipe is connected to the lower part of the heat storage chamber, and the flue pipe is provided with a chimney capable of sucking exhaust gas discharged from the combustion chamber through the heat storage chamber and releasing it to the outside. A flue valve for controlling the flow of the exhaust gas is provided between the heat storage chamber and the chimney in the flue pipe,
Before the draft wind forming step, the flue valve is opened, and the draft air flowing through the hot air outlet pipe, the mixing chamber, the combustion chamber, the heat storage chamber, the flue pipe, and the chimney in order. Implement the draft flow path securing process to secure the flow path,
In the draft air forming step, the hot air valve is removed, and the hot air outlet pipe is provided with the opening to form the draft air. In the heat insulation method at the time of hot-air duct repair in any one of Claims 1 thru / or 7,
The hot air duct is
A hot air outlet pipe that is formed in a tubular shape extending substantially along the horizontal direction, one end of which is connected to the combustion chamber, and allows hot air from the heat storage chamber to be introduced into the blast furnace through the combustion chamber;
A hot air main pipe formed in a tubular shape extending substantially along the horizontal direction, connected to the other end of the hot air outlet pipe, and capable of supplying hot air introduced from the hot air outlet pipe to the tuyere of the blast furnace; , And
In the breathable member installation step and the fire wall construction step, the heat cutoff scheduled position is set in the hot air outlet pipe or in the hot air main pipe. In the heat shut-off method at the time of hot air duct repair according to claim 11,
The hot air outlet pipe is detachably provided with a hot air valve that opens and closes the flow path in the pipe,
The hot air main pipe is provided with a bleeder that can suck and discharge the gas in the flow path in the pipe to the outside, and a bleeder valve that controls the flow of the gas to the bleeder,
Prior to the draft air forming step, a draft flow passage securing step is performed in which the bleeder valve is opened to secure the draft air flow passage that sequentially flows through the hot air outlet pipe, the hot air main pipe, and the bleeder. Carried out,
In the draft air forming step, the hot air valve is removed, thereby providing the opening in the hot air outlet pipe to form the draft air. . In the heat insulation method at the time of hot-air duct repair in any one of Claims 1 thru / or 12,
After the refractory wall construction step, a hot air duct repair is performed, in which a combustion gas is combusted in the combustion chamber, and a heat retaining step is performed to maintain the temperature in the combustion chamber and the heat storage chamber at a high temperature. This is a method for shutting off heat at the time.

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