JP2021134997A - Cooling device and cooling method for continuous type steel heating furnace - Google Patents

Abstract

To provide a cooling device and a cooling method for a continuous type steel heating furnace, in a continuous type steel heating furnace in which all combustion burners in a furnace body are made into heat storage type switching combustion burners, capable of reducing cooling time without damaging refractories in the furnace body.SOLUTION: A cooling device 10 for a continuous type steel heating furnace comprises a fan 27 for suction exhaust gas suction sucking a suction exhaust gas from all heat storage type switching burners 20 via a suction exhaust gas flow rate adjustment valve 26, a furnace tail exhaust gas exhaust apparatus 12 installed in a flue 8 provided at a position on the downstream side than a combustion control zone 3 on the most downstream side in the exhaust gas flow of a furnace body 2 and comprising a furnace pressure damper 9 adjusting furnace pressure and a chimney 11 exhausting a furnace tail exhaust gas passed through the furnace pressure damper and a fan 16 for furnace tail exhaust gas suction connected to an exhaust gas exhaust passage 13 provided at a position on the downstream side than the combustion control zone 3 and sucking the furnace tail exhaust gas from the combustion control zone 3 via a furnace tail exhaust gas flow rate adjustment valve 15.SELECTED DRAWING: Figure 1

Description

The present invention relates to a cooling device and a cooling method for a continuous steel heating furnace in which all of the combustion burners in the furnace are heat storage type switching combustion burners.

In a continuous steel heating furnace that continuously heats a material to be heated such as a slab, the furnace pressure in the heating furnace is adjusted during normal operation, and the charging door for charging the material to be heated and the material to be heated are used. It is operated so that the internal gas of the heating furnace is not discharged from the extraction door for extracting the furnace and the air does not enter. Then, the exhaust gas in the heating furnace is guided to the chimney through the flue installed at the most downstream position in the exhaust gas flow of the furnace body, and is discharged to the outside. Further, the furnace pressure in the heating furnace is adjusted by the furnace pressure damper installed in the flue described above.

Here, in a normal heating furnace that does not use a heat storage type switching combustion burner as the combustion burner in the furnace, all the exhaust gas in the heating furnace passes through the furnace pressure damper and is discharged to the outside from the chimney by the draft effect.
On the other hand, in the case of a heating furnace in which all the combustion burners in the furnace are heat storage type switching combustion burners, 80 to 100% of the generated exhaust gas is sucked from all the heat storage type switching combustion burners, and the suction thereof. The exhaust gas is guided to the exhaust gas attraction fan through the heat storage body, and then returned to the chimney and discharged to the outside. On the other hand, 0 to 20% of the exhaust gas that is not sucked by the heat storage type switching combustion burner passes through the furnace pressure damper installed in the flue and is discharged to the outside from the chimney.

In a heating furnace in which all of the combustion burners in the furnace are heat storage type switching combustion burners, in the periodic repair involving cooling in the furnace, the operation is terminated by quickly lowering the temperature in the heating furnace. It is possible to shorten the time from the completion of the repair to the start of the next operation. When cooling such a heating furnace, generally, the furnace pressure damper is fully opened so that as much air as possible is discharged from the heating furnace to the chimney. At this time, the charging door and the extraction door are fully opened so that the surrounding air can be easily sucked. In addition, combustion air is blown from the heat storage type switching combustion burner to increase the amount of air discharged from the chimney as much as possible.

In addition, the conventional patent document 1 describes an air cooling step performed in a state where the refractory and the atmospheric temperature in the furnace are over 800 ° C., and cooling water when the refractory and the atmospheric temperature in the furnace becomes 800 ° C. or less. A water cooling method for a heating furnace including a water cooling process performed by supplying it into the furnace is described. In this water cooling process, the cooling water is atomized and sprayed over the entire furnace and sprinkled toward the sedimentary scale at the bottom of the furnace.

Japanese Patent No. 5736657

Here, in the above-mentioned cooling of the heating furnace in which all of the combustion burners in the furnace are heat storage type switching combustion burners, the furnace pressure damper is fully opened and as much air as possible is discharged from the heating furnace to the chimney. ing. However, because the height of the chimney is set low (the height of the chimney of a normal heating furnace that does not use a heat storage type switching combustion burner as a combustion burner is about 100 m, whereas the height of the combustion burner inside the furnace is about 100 m. A heating furnace that uses a heat storage type switching combustion burner for all (about 40 m) cannot obtain a sufficient draft effect, and a normal heating furnace that does not use a heat storage type switching combustion burner as a combustion burner when cooling the heating furnace. There was a problem that it required more cooling time.

On the other hand, raising the chimney unnecessarily during normal operation just to accelerate the cooling of the heating furnace makes it difficult to adjust the furnace pressure during normal operation, resulting in an increase in invading air. It is not desirable because of the influence of such factors.
In the method of atomizing the cooling water into a mist and spraying it into the furnace as described in Patent Document 1, the amount of water that can be sprayed is increased because the nozzle that generates the mist needs to reduce the droplet diameter. It was not so large, the cooling effect was limited, and the nozzle was sometimes clogged. When the nozzle is clogged, the diameter of the droplet becomes large and a puddle is formed in the heating furnace, which causes a problem such as damage to the refractory in the furnace.

Therefore, the present invention has been made to solve these conventional problems, and an object of the present invention is to use a continuous steel heating furnace in which all of the combustion burners in the furnace are heat storage type switching combustion burners. It is an object of the present invention to provide a cooling device and a cooling method for a continuous steel heating furnace capable of shortening the cooling time without damaging the refractory.

In order to achieve the above object, the cooling device of the continuous steel heating furnace according to one aspect of the present invention includes a furnace body having a plurality of combustion control zones along the direction of the furnace length, and each of the plurality of combustion control zones. It is a cooling device of a continuous steel heating furnace provided with a plurality of combustion burners installed in the above and all of the plurality of combustion burners are heat storage type switching combustion burners, and suction from all the heat storage type switching combustion burners. A suction exhaust gas suction fan that sucks exhaust gas through a suction exhaust gas flow rate adjusting valve, and a furnace installed in a flue provided at a position downstream of the combustion control zone on the most downstream side in the exhaust gas flow of the furnace body. A furnace pressure damper equipped with a furnace pressure damper for adjusting the pressure and a chimney for discharging the furnace tail exhaust gas passing through the furnace pressure damper, and a furnace tail exhaust gas discharge device on the downstream side of the combustion control zone on the most downstream side in the exhaust gas flow of the furnace body. It is provided with a furnace tail exhaust gas suction fan that is connected to the exhaust gas discharge path provided at the position and sucks the furnace tail exhaust gas from the most downstream combustion control band through the furnace tail exhaust gas flow rate adjusting valve. It is a summary.

Further, the cooling method of the continuous steel heating furnace according to another aspect of the present invention is a continuous steel heating furnace that cools the inside of the continuous steel heating furnace by using the cooling device of the continuous steel heating furnace described above. When cooling the inside of the furnace, the suction exhaust gas suction fan is opened by fully opening the valve opening of the suction exhaust gas flow rate adjusting valve with the charging door and the extraction door open. By driving, the suction exhaust gas is sucked and discharged, the furnace pressure damper is fully opened, the air that has passed through the furnace pressure damper is discharged from the chimney, and the valve opening of the furnace tail exhaust gas flow rate adjusting valve is fully opened. The gist is that the air from the most downstream combustion control band is sucked and discharged by driving the furnace tail exhaust gas suction fan.

According to the cooling device and cooling method of the continuous steel heating furnace according to the present invention, in the continuous steel heating furnace in which all the combustion burners in the furnace are heat storage type switching combustion burners, the fireproof material in the furnace is not damaged. It is possible to provide a cooling device and a cooling method for a continuous steel heating furnace capable of shortening the cooling time.

It is a figure which shows the schematic structure of the cooling device of the continuous steel material heating furnace which concerns on one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments shown below exemplify devices and methods for embodying the technical idea of the present invention, and the technical idea of the present invention describes the material, shape, structure, arrangement, etc. of the components. It is not specified in the following embodiments.
The drawings are schematic. Therefore, it should be noted that the relationship, ratio, etc. between the thickness and the plane dimension are different from the actual ones, and there are parts where the relationship and ratio of the dimensions are different between the drawings.

FIG. 1 shows a schematic configuration of a cooling device for a continuous steel heating furnace according to an embodiment of the present invention.
In FIG. 1, the continuous steel heating furnace 1 heats the steel material S as the material to be heated, and extends in the furnace length method (front-rear direction shown on the left and right in FIG. 1) which is the transport direction of the steel material S. It has a body 2. The furnace body 2 includes a pre-tropical 3, a first heating zone 4, a second heating zone 5, and an average tropical 6 as combustion control zones along the furnace length direction from the charging side to the extraction side of the steel material S. Prepared in order. In FIG. 1, the horizontal direction, which is the width direction of the furnace body 2, is shown vertically on the extraction side of the pre-tropical 3 and the vertical direction, which is the height direction of the furnace body 2, is shown on the charging side of the pre-tropical 3 Illustrated above and below.

Further, a charging door 7a for opening and closing the charging inlet of the furnace body 2 is installed at the charging side (rear side) end of the furnace body 2, and the furnace body 2 is installed at the extraction side (front side) end of the furnace body 2. An extraction door 7b that opens and closes the extraction port of the above is installed.
In addition, each of the pre-tropical 3, the first heating zone 4, the second heating zone 5, and the average tropical 6 has a plurality (6 in the present embodiment, 3 in the upper part, 3 in the lower part). A combustion burner 20 is provided. All of the plurality of combustion burners 20 are composed of heat storage type combustion switching burners, and all of the combustion burners 20 in the furnace body 2 are heat storage type combustion switching burners. Hereinafter, this heat storage type combustion switching burner will be described as the heat storage type switching combustion burner 20.

Each heat storage type switching combustion burner 20 is a pair of heat storage type burners 20a, 20b installed on the left and right facing the furnace walls of each pre-tropical 3, first heating zone 4, second heating zone 5, and average tropical 6. Consists of. Each of the heat storage type burners 20a and 20b includes heat storage bodies 21a and 21b made of ceramic balls or the like, respectively. Then, the heat storage type burners 20a and 20b are alternately burned, and the inside of the furnace body 2 through the non-combustion type heat storage type burners 20a or 20b, that is, each pre-tropical 3, first heating zone 4, second heating zone. The exhaust gas from combustion is discharged from the heat storage body 21a or 21b through the heat storage body 21a or 21b. As a result, the heat of the sucked exhaust gas is stored in the heat storage body 21a or 21b, and the combustion air is supplied to the heat storage type burner 20a or 20b via the heat storage body 21a or 21b at the time of the next combustion, thereby supplying the exhaust gas heat. It is used for preheating fuel gas.

The heat storage body 21a of the heat storage type burner 20a on one side is connected to the exhaust gas header pipe 23a in which the exhaust gas switching valve 22a is installed, and the heat storage body 11b of the heat storage type burner 10b on the other side is provided with the exhaust gas switching valve 22b. It is connected to the exhaust gas header pipe 23b. Then, all the exhaust gas header pipes 23a in each of the pre-tropical 3, the first heating zone 4, the second heating zone 5, and the average tropical 6 are gathered in the first exhaust gas collecting pipe 24a, and the pre-tropical 3, the first heating zone 4. All the exhaust gas header pipes 23b in each of the second heating zone 5 and the solitary tropics 6 are gathered in the second exhaust gas collecting pipe 24b. The first exhaust gas collecting pipe 24a and the second exhaust gas collecting pipe 24b are gathered in the common exhaust gas collecting pipe 25. The exhaust gas collecting pipe 25 is connected to the downstream side of the furnace pressure damper 9 of the flue 8 described later, and the sucked exhaust gas from each heat storage type switching combustion burner 20 flowing in the exhaust gas collecting pipe 25 is discharged to the flue 8. It has become like.
Further, the exhaust gas collecting pipe 25 includes a suction exhaust gas flow rate adjusting valve 26 for the suction exhaust gas from all the heat storage type switching combustion burners 20 and a suction exhaust gas suction fan for sucking the suction exhaust gas through the suction exhaust gas flow rate adjustment valve 26. 27 and are installed.

Further, the heat storage body 21a of the heat storage type burner 20a on one side is connected to the combustion air header pipe 29a in which the combustion air switching valve 28a is installed, which is branched from the exhaust gas header pipe 23a, and is connected to the heat storage type burner 20b on the other side. The heat storage body 21b is connected to a combustion air header pipe 29b in which a combustion air switching valve 28b is installed, which is branched from the exhaust gas header pipe 23b. Then, the combustion air header pipes 29a in each of the pre-tropics 3, the first heating zone 4, the second heating zone 5, and the average tropics 6 gather in the combustion air collecting pipes 30a for each combustion control zone, and the pre-tropics 3 , The first heating zone 4, the second heating zone 5, and the combustion air header pipe 29b of the solitary tropics 6 are gathered in the combustion air collecting pipe 30b for each combustion control zone. Combustion air flow rate control valves 31a and 31b are installed in each combustion air collecting pipe 30a and each combustion air collecting pipe 30b. Then, all the combustion air collecting pipes 30a of the pre-tropical 3, the first heating zone 4, the second heating zone 5, and the average tropical 6 are gathered in the first combustion air collecting pipe 32a, and the pre-tropical 3 and the first All the combustion air collecting pipes 30b of the 1 heating zone 4, the 2nd heating zone 5, and the solitary tropics 6 are gathered in the 2nd combustion air collecting pipe 32b. The first combustion air collecting pipe 32a and the second combustion air collecting pipe 32b are connected to the common combustion air supply main 33, and the combustion air supply main 33 is connected to the combustion air blower 34. There is.

Although not shown, a fuel gas header pipe is connected to each of the heat storage type burner 20a on one side and the heat storage type burner 20b on the other side, and fuel gas is alternately supplied to the heat storage type burners 20a and 20b, respectively. It has become like.
Further, in the furnace body 2, the flue 8 is installed at a position on the downstream side (rear side) of the combustion control zone on the most downstream side in the exhaust gas flow, that is, a position on the downstream side of the pretropical zone 3. Since the exhaust gas flows from the extraction side of the furnace body 2 toward the charging side in the furnace body 2, the position on the downstream side of the pre-tropical 3 is the charging side of the pre-tropical 3 (rear side in FIG. 1). ) Position. A furnace pressure damper 9 for adjusting the furnace pressure is installed in the flue 8.

Further, a chimney 11 is installed on the downstream side of the exhaust gas flow of the flue 8. The furnace butt exhaust gas from the pre-tropical 3 is guided to the flue 8, reaches the chimney 11 through the furnace pressure damper 9, rises due to the draft effect, and is discharged to the outside. The height h of the chimney 11 is as low as about 40 m, while the height of the chimney of a normal heating furnace that does not use the heat storage type switching combustion burner 20 as the combustion burner is about 100 m. The reason for this is that in the case of a normal heating furnace, the combustion gas is discharged using the draft force of the chimney, whereas all of the combustion burners 20 in the furnace body 2 are heating furnaces using a heat storage type combustion switching burner. In this case, the combustion gas is discharged using the suction exhaust gas suction fan 27.

Further, in the continuous steel heating furnace 1, the operation may be temporarily stopped for periodic repair or the like to cool the furnace body 2. Therefore, the continuous steel heating furnace 1 is provided with a cooling device 10 for cooling the furnace body 2.
The cooling device 10 includes the above-mentioned charging door 7a and extraction door 7b, and a flue 8 provided at a position downstream of the combustion control zone on the most downstream side in the exhaust gas flow of the furnace body 2, that is, the pre-tropical zone 3. It is equipped with the above-mentioned furnace pressure damper 9 for adjusting the furnace pressure and the furnace butt exhaust gas discharge device 12 provided with the above-mentioned chimney 11 for discharging the furnace butt exhaust gas passing through the furnace pressure damper 9.

When cooling the continuous steel heating furnace 1 in which all of the combustion burners in the furnace body 2 are heat storage type switching combustion burners 20, generally, the furnace pressure damper 9 of the furnace tail exhaust gas discharge device 12 is fully opened. As much air as possible is discharged from the furnace body 2 to the chimney 11. At this time, the charging door 7a and the extraction door 7b are fully opened so that the surrounding air can be easily sucked. Further, combustion air is blown from each of the plurality of heat storage type switching combustion burners 20 to increase the amount of air discharged from the chimney 11 as much as possible.

However, as described above, since the height h of the chimney 11 is set as low as about 40 m, a sufficient draft effect cannot be obtained, and a heat storage type is used as a combustion burner when cooling the furnace body 2. It will take more cooling time than a normal heating furnace that does not use a switching combustion burner. If the cooling time is long, the time from the end of the operation to the completion of the repair and the start of the next operation becomes long, and the productivity deteriorates.
On the other hand, raising the chimney unnecessarily during normal operation just to accelerate the cooling of the furnace body 2 makes it difficult to adjust the furnace pressure during normal operation, resulting in an increase in invading air. It is not desirable because of the influence of such factors.

Therefore, in the present embodiment, the cooling device 10 uses the suction exhaust gas from all the heat storage type switching combustion burners 20 described above in addition to the furnace tail exhaust gas discharge device 12 provided with the furnace pressure damper 9 and the chimney 11 described above. As a configuration including a suction exhaust gas suction fan 27 that sucks through the suction exhaust gas flow rate adjusting valve 26, the suction exhaust gas from all the heat storage type switching combustion burners 20 is discharged, and the furnace butt exhaust gas suction fan 16 described below is used. As a configuration to be provided, the furnace butt exhaust gas from the most downstream pre-tropical zone 3 is sucked through the furnace butt exhaust gas flow rate adjusting valve 15.

That is, in the present embodiment, the cooling device 10 is connected to the exhaust gas discharge path 13 provided at a position downstream (rear side) of the most downstream side of the pre-tropical zone 3 in the exhaust gas flow of the furnace body 2, and is connected to the most downstream side. The furnace butt exhaust gas suction fan 16 for sucking the furnace butt exhaust gas from the side pre-tropical 3 via the furnace butt exhaust gas flow rate adjusting valve 15 is provided. The furnace butt exhaust gas flow rate adjusting valve 15 and the furnace butt exhaust gas suction fan 16 are installed in an exhaust gas pipe 14 extending from the exhaust gas discharge path 13 to the heat retaining pit 17, which will be described later.

Further, the cooling device 10 controls the opening / closing of the charging door 7a and the extraction door 7b, the opening degree control of the furnace pressure damper 9, and the suction exhaust gas flow rate adjusting valve 26 based on the cooling start instruction and the heating operation instruction from the host computer 19. A cooling control unit 18 that controls the valve opening degree, drives the suction exhaust gas suction fan 27, controls the valve opening degree of the furnace butt exhaust gas flow rate adjusting valve 15, and drives the furnace butt exhaust gas suction fan 16. There is.
When the exhaust gas flow rate generated at the maximum combustion load by the heat storage type switching combustion burner 20 is XNm ³ / H, the suction exhaust gas suction fan 27 has a flow rate of 1.0 XNm ³ / H or more and a temperature of 300 ° C. or less. the suction gas sucked in, chimney 11, the flow rate is discharged 1.2XNm ³ / H or more and the temperature is 300 ° C. to 500 ° C. oven butt exhaust gas, the furnace butt exhaust gas suction fan 16, 0.4XNm ³ It is preferable to suck the exhaust gas from the furnace butt at a temperature of / H or more and a temperature of 900 ° C. or less.

The reason why the suction exhaust gas suction fan 27 sucks the suction exhaust gas having a flow rate of 1.0 XNm ³ / H or more is that the cooling time is shortened without damaging the fireproof material in the furnace body 2 which is the object of the present invention. The reason why the suction exhaust gas having a temperature of 300 ° C. or lower is specified to be sucked is that the heat resistance of the valve or the like used in the heat storage type switching combustion burner 20 is 300 ° C.
Further, the reason why the chimney 11 stipulates that the furnace exhaust gas having a flow rate of 1.2 XNm ³ / H or more is discharged is that the gas generated by combustion and the air entering from the charging door 7a and the extraction door 7b are taken into consideration. This is because it is necessary to be able to discharge gas with some margin, and the reason why it is specified to discharge the furnace butt exhaust gas with a temperature of 300 ° C to 500 ° C is that it is discharged from the heat storage type switching combustion burner 20. This is because it is a mixture of a gas having a temperature of 300 ° C. or lower and a gas having a temperature of 500 to 800 ° C. discharged from the furnace butt.

Further, the reason why the furnace butt exhaust gas suction fan 16 is ^{specified to suck the furnace butt exhaust gas having a flow rate of 0.4XNm 3} / H or more is that the suction exhaust gas suction fan 27 and the furnace butt exhaust gas suction fan 16 are operated at the same time. This is to enable all the generated gas to be discharged without increasing the amount of air entering from the charging door 7a and the extraction door 7b, and it is stipulated that the exhaust gas from the furnace butt where the temperature is 900 ° C or less is sucked. The reason is that the exhaust gas temperature at the furnace butt is 400 to 900 ° C.

Further, the cooling device 10 includes a heat retaining pit 17 into which the furnace butt exhaust gas sucked by the furnace butt exhaust gas suction fan 16 is introduced. The heat retaining pit 17 is connected to the exhaust gas pipe 14. The steel material S scheduled to be heated by the continuous steel material heating furnace 1 is stored in the heat retention pit 17, and the steel material S is preheated by the furnace tail exhaust gas introduced into the heat retention pit 17 during normal heating operation. Can be done.
Here, the meaning of the cooling device 10 including the heat retaining pit 17 into which the furnace butt exhaust gas sucked by the furnace butt exhaust gas suction fan 16 is introduced will be described in detail.

During normal heating operation, the suction exhaust gas sucked from the heat storage type switching combustion burner 20 is heat-exchanged by the heat storage body 21a or 21b, and is cooled from the furnace temperature (about 1000 to 1200 ° C.) to about 300 ° C. , Converted to the heat of combustion air. Generally, in combustion, since the amount of exhaust gas is larger and the specific heat is higher than that of combustion air, it is generally impossible to suck 100% of the exhaust gas generated even in the heat storage type switching combustion burner 20. In the case of the heat storage type switching combustion burner 20 using the by-product gas of the steelworks, the suction rate of the generated exhaust gas is limited to about 80%. Therefore, the exhaust gas directly guided to the chimney 11 is present in about 20% of the generated exhaust gas, but heat exchange cannot be performed even though the exhaust gas has a high temperature of about 800 to 1000 ° C.

On the other hand, since the cooling device 10 includes a heat retaining pit 17 into which the furnace butt exhaust gas sucked by the furnace butt exhaust gas suction fan 16 is introduced, the continuous steel heating furnace 1 is provided in the heat retaining pit 17. The steel material S to be heated is stored. As a result, the steel material S can be preheated by the furnace tail exhaust gas (the above-mentioned high-temperature exhaust gas of about 800 to 1000 ° C.) introduced into the heat retaining pit 17 during normal heating operation, and the continuous steel material heating furnace 1 can be used. The fuel intensity can be lowered.

Next, a cooling method for cooling the inside of the furnace body 2 of the continuous steel heating furnace 1 using the cooling device 10 will also be described.
When the cooling control unit 18 receives a cooling start instruction from the host computer 19, the cooling control unit 18 starts the cooling control of the continuous steel heating furnace 1.
In this cooling control, first, the cooling control unit 18 fully opens the charging door 7a and the extraction door 7b. The reason for this is to facilitate suction of the air around the furnace body 2.

Next, the cooling control unit 18 controls to drive the suction exhaust gas suction fan 27 by fully opening the valve opening degree of the suction exhaust gas flow rate adjusting valve 26 in a state where the charging door 7a and the extraction door 7b are fully opened. As a result, the suction exhaust gas suction fan 27 ^{sucks the suction exhaust gas from the heat storage type switching combustion burner 20 having a flow rate of 1.0 XNm 3} / H or more, and the sucked exhaust gas is discharged into the chimney 11. At this time, the temperature of the suction exhaust gas from the heat storage type switching combustion burner 20 is about 300 ° C. The exhaust gas flow rate generated at the maximum combustion load by the heat storage type switching combustion burner 20 is defined as XNm ³ / H.

Next, the cooling control unit 18 controls the furnace pressure damper 9 to be fully opened and discharges the air (including the furnace tail exhaust gas) that has passed through the furnace pressure damper 9 from the chimney 11. At this time, air (including the exhaust gas from the furnace butt) having a flow rate of 1.2 XNm ³ / H or more and a temperature of 300 ° C. to 500 ° C. is discharged at the maximum. Since all of the combustion burners in the furnace body 2 are heat storage type switching combustion burners 20 and the height h of the chimney 11 is as low as 40 m, the draft effect is insufficient and the displacement from the chimney 11 is not sufficient.
Finally, the cooling control unit 18 controls to drive the furnace butt exhaust gas suction fan 16 by fully opening the valve opening degree of the furnace butt exhaust gas flow rate adjusting valve 15. As a result, the air (including the furnace butt exhaust gas) from the most downstream pre-tropical 3 is sucked through the exhaust gas discharge path 13 and the furnace butt exhaust gas flow rate adjusting valve 15 and discharged to the heat retaining pit 17.

According to the cooling device 10 and the cooling method of the continuous steel heating furnace according to the present embodiment, when the inside of the furnace body 2 is cooled in this way, the charging door 7a and the extraction door 7b are fully opened. The suction exhaust gas is sucked and discharged by driving the suction exhaust gas suction fan 27 with the valve opening degree of the suction exhaust gas flow rate adjusting valve 26 fully opened. Further, the furnace pressure damper 9 is fully opened and the air that has passed through the furnace pressure damper 9 is discharged from the chimney 11. Further, the valve opening degree of the furnace butt exhaust gas flow rate adjusting valve 15 is fully opened and the furnace butt exhaust gas suction fan 16 is driven to suck and discharge the air from the most downstream pre-tropical zone 3.

Therefore, in addition to the exhaust of the air in the furnace body 2 due to the draft effect from the chimney 11, the exhaust gas in the furnace body 2 is exhausted by using the suction exhaust gas suction fan 27 of the suction exhaust gas from the heat storage type switching combustion burner 20. The amount of exhaust gas in the furnace body 2 can be further increased by using the furnace tail exhaust gas suction fan 16 which can directly discharge the air in the furnace body 2.
As a result, even when the height h of the chimney 11 is as low as 40 m, all of the combustion burners in the furnace body 2 are used as the heat storage type switching combustion burner 20, and the insufficient draft effect is sucked from the heat storage type switching combustion burner 20. Exhaust gas suction The exhaust gas amount in the furnace body 2 is increased by using the exhaust gas suction fan 27, and the furnace body is further increased by using the furnace tail exhaust gas suction fan 16 capable of directly discharging the air in the furnace body 2. The amount of exhaust gas in the furnace body 2 can be increased and the cooling time of the furnace body 2 can be shortened.

Further, since air (including exhaust gas) is used for cooling the furnace body 2 and no mist is used, no puddle is formed in the furnace body 2 and the refractory in the furnace body 2 is damaged. It's not.
As a result, according to the cooling device 10 and the cooling method of the continuous steel heating furnace according to the present embodiment, in the continuous steel heating furnace 1 in which all the combustion burners in the furnace body 2 are heat storage type switching combustion burners 20. It is possible to provide a cooling device and a cooling method for a continuous steel heating furnace capable of shortening the cooling time without damaging the fireproof material in the furnace body 2.

Further, when the cooling control unit 18 receives a heating operation instruction from the host computer 19, the cooling control of the continuous steel heating furnace 1 is stopped, the opening / closing control of the charging door 7a and the extraction door 7b in the normal operating state, and the furnace pressure. Control of the opening degree of the damper 9, control of the valve opening degree of the suction exhaust gas flow rate adjusting valve 26, drive control of the suction exhaust gas suction fan 27, control of the valve opening degree of the furnace butt exhaust gas flow rate adjusting valve 15, and for suction of the furnace butt exhaust gas Drive control of the fan 16 is performed.
In this control, first, the cooling control unit 18 closes the charging door 7a and the extraction door 7b.

Next, the cooling control unit 18 assumes that the valve opening degree of the suction exhaust gas flow rate adjusting valve 26 is in a normal operating state, and stores the suction exhaust gas of about 80% of the exhaust gas amount generated by the combustion of the heat storage type switching combustion burner 20 as a heat storage body. After cooling to about 300 ° C. through 21a or 21b, the suction exhaust gas suction fan 27 is controlled to be driven. At this time, the cooling control unit 18 controls the furnace pressure damper 9 to be fully closed. As a result, the suction exhaust gas from the heat storage type switching combustion burner 20 is sucked in a state where the furnace tail exhaust gas is not discharged from the chimney 11 after passing through the furnace pressure damper 9, and the sucked exhaust gas is discharged into the chimney 11. ..

Next, the cooling control unit 18 drives the furnace butt exhaust gas suction fan 16 after adjusting the valve opening degree of the furnace butt exhaust gas flow rate adjusting valve 15 so that the furnace pressure in the furnace body 2 is about 0 to 10 Pa. Control. As a result, the hot furnace exhaust gas from the most downstream pre-tropical 3 is sucked through the exhaust gas discharge path 13 and the furnace tail exhaust gas flow rate adjusting valve 15 and introduced into the heat retaining pit 17.
The steel material S to be heated by the continuous steel material heating furnace 1 is stored in the heat retention pit 17, and the steel material S is preheated by the high-temperature furnace butt exhaust gas introduced into the heat retention pit 17.

The furnace body 2 was cooled in the continuous steel heating furnace 1 shown in FIG. 1, which had a furnace body 2 having a furnace length of 35 m, a furnace width of 13 m, and a furnace height of 4.8 m and equipped with a cooling device 10. The height h of the chimney 11 in this continuous steel heating furnace 1 is 40 m. Table 1 shows the results of the cooling conditions and the cooling time in the furnace.

The “in-furnace cooling time” in Table 1 refers to the time from when cooling starts at a furnace temperature of 1000 ° C. or higher to when the furnace temperature drops to 50 ° C. or lower.
In Comparative Example 1, only the draft effect was exhausted from the chimney 11, and the suction exhaust gas was not exhausted by the suction exhaust gas suction fan 27 and the furnace butt exhaust gas suction fan 16 was not exhausted. Further, in Comparative Example 1, combustion air was not sent into the furnace body 2 from all the heat storage type switching combustion burners 20.

Further, in Comparative Example 2, only the draft effect was exhausted from the chimney 11, and the suction exhaust gas was not exhausted by the suction exhaust gas suction fan 27 and the furnace butt exhaust gas suction fan 16 was not exhausted. Further, in Comparative Example 2, combustion air having a ^{flow rate of 60,000 Nm 3} / H was sent into the furnace body 2 from all the heat storage type switching combustion burners 20.
As can be seen from Table 1, the displacement of the entire furnace according to Comparative Example 1 is 146476 Nm ³ / H, and the displacement of the entire furnace according to Comparative Example 2 is 146591 Nm ³ / H. Even if combustion air is sent into 2, the displacement of the entire furnace does not increase. Further, the cooling time in the furnace is not shortened to 45.3 Hr in the case of Comparative Example 1 and 45.2 Hr in the case of Comparative Example 2.

Further, in Comparative Example 3, only the draft effect was exhausted from the chimney 11 and the suction exhaust gas was exhausted by the suction exhaust gas suction fan 27, but not by the furnace butt exhaust gas suction fan 16. Further, in Comparative Example 3, combustion air was not sent into the furnace body 2 from all the heat storage type switching combustion burners 20.
As can be seen from Table 1, the displacement of the entire furnace according to Comparative Example 1 is 146476 Nm ³ / H, the displacement of the entire furnace according to Comparative Example 3 is 192198 Nm ³ / H, and the cooling time in the furnace is 35.2 Hr. It was shortened. The exhaust gas of the suction exhaust gas by the suction exhaust gas suction fan 27 had the effect of increasing the displacement of the entire furnace, but the displacement of the entire furnace as compared with the case of Example 1 and the case of Example 2 described later. The increasing effect is small.

On the other hand, in Examples 1 and 2, only the draft effect was exhausted from the chimney 11, the suction exhaust gas was exhausted by the suction exhaust gas suction fan 27, and the exhaust gas was exhausted by the furnace butt exhaust gas suction fan 16. In the first embodiment, the displacement by the furnace butt exhaust gas suction fan 16 is 50,000 Nm ³ / H, and in the second embodiment, the displacement by the furnace butt exhaust gas suction fan 16 is 100,000 Nm ³ / H. Further, in Examples 1 and 2, combustion air was not sent into the furnace body 2 from all the heat storage type switching combustion burners 20.

As can be seen from Table 1, the displacement of the entire furnace according to Example 1 is 242198 Nm ³ / H, and the displacement of the entire furnace according to Example 2 is 292198 Nm ³ / H, not only in the case of Comparative Example 1. The displacement of the entire furnace was increased as compared with the case of Comparative Example 3. Further, the cooling time in the furnace according to Example 1 was 27.0 Hr, and the cooling time in the furnace according to Example 2 was 23.5 Hr. Cooling time has been shortened.
Further, in the case where the furnace tail exhaust gas from the most downstream pre-tropical 3 among the exhaust gas generated during normal operation is introduced into the heat retaining pit 17 to preheat the steel material S and heat the steel material S (Example 2 of the present invention). ), And the case where the furnace butt exhaust gas from the most downstream pre-tropical 3 among the exhaust gas generated during normal operation is discharged and the steel material S is heated without preheating the steel material S (Example 1 of the present invention). A comparison was made. The results are shown in Table 2.

In the case of Example 1 of the present invention in which the steel material S is not preheated, the average temperature of the steel material S charged into the continuous steel material heating furnace 1 is 50.0 ° C., and in the case of Example 2 of the present invention in which the steel material S is preheated. The average temperature of the steel material S charged into the continuous steel material heating furnace 1 was 150.0 ° C., and the average temperature of the steel material S charged increased by preheating the steel material S in the heat retaining pit 17. .. As a result, it was confirmed that the fuel intensity was reduced.

1 Continuous steel heating furnace 2 Furnace 3 Pre-tropical (combustion control zone)
4 First heating zone (combustion control zone)
5 Second heating zone (combustion control zone)
6 Even tropics (combustion control zone)
7a Charge door 7b Extraction door 8 Smokeway 9 Combustion pressure damper 10 Cooling device 11 Chimney 12 Furnace exhaust gas discharge device 13 Exhaust gas discharge path 14 Exhaust pipe 15 Combustion tail exhaust gas flow control valve 16 Furnace exhaust gas suction fan 17 Heat insulation pit 18 Cooling control unit 19 High-end computer 20 Heat storage type switching combustion burner 20a, 20b Heat storage type burner 21a, 21b Heat storage body 22a, 22b Exhaust gas switching valve 23a, 23b Exhaust gas header pipe 24a 1st exhaust gas collecting pipe 24b 2nd exhaust gas collecting pipe 25 Exhaust gas Collecting pipe 26 Suction exhaust gas flow control valve 27 Suction exhaust gas suction fan 28a, 28b Combustion air switching valve 29a, 29b Combustion air header pipe 30a, 30b Combustion air collecting pipe 31a, 31b Combustion air flow control valve 32a 1st Combustion air collecting pipe 32b Second combustion air collecting pipe 33 Combustion air supply main 34 Combustion air blower S Steel material

Claims (4)

A furnace body having a plurality of combustion control bands along the furnace length direction and a plurality of combustion burners installed in each of the plurality of combustion control bands are provided, and all of the plurality of combustion burners are heat storage type switching combustion burners. It is a cooling device for a continuous steel heating furnace.
A suction exhaust gas suction fan that sucks the suction exhaust gas from all the heat storage type switching combustion burners through the suction exhaust gas flow control valve,
A furnace pressure damper installed in a chimney provided at a position downstream of the combustion control zone on the most downstream side in the exhaust gas flow of the furnace body and a furnace pressure damper that adjusts the furnace pressure and a furnace tail exhaust gas that has passed through the furnace pressure damper are discharged. A fire pit exhaust gas discharge device equipped with a chimney
It is connected to an exhaust gas discharge path provided at a position downstream of the most downstream combustion control zone in the exhaust gas flow of the furnace body, and the furnace butt exhaust gas from the most downstream combustion control zone is adjusted to the furnace butt exhaust gas flow rate. A cooling device for a continuous steel heating furnace, which is provided with a fan for sucking exhaust gas from the furnace butt that sucks through a valve. When the exhaust gas flow rate generated at the maximum combustion load by the heat storage type switching combustion burner is XNm ³ / H, the suction exhaust gas suction fan sucks at a flow rate of 1.0 XNm ³ / H or more and a temperature of 300 ° C. or less. The exhaust gas is sucked, the chimney ^{discharges the furnace butt exhaust gas having a flow rate of 1.2 XNm 3} / H or more and a temperature of 300 ° C. to 500 ° C., and the furnace butt exhaust gas suction fan has a flow rate of 0.4 XNm ³ The cooling device for a continuous steel heating furnace according to claim 1, wherein the exhaust gas from the furnace bottom having a temperature of / H or more and a temperature of 900 ° C. or less is sucked. The cooling device for a continuous steel heating furnace according to claim 1 or 2, further comprising a heat retaining pit into which the furnace butt exhaust gas sucked by the furnace butt exhaust gas suction fan is introduced. A cooling method for a continuous steel heating furnace in which the inside of the continuous steel heating furnace is cooled by using the cooling device for the continuous steel heating furnace according to any one of claims 1 to 3.
When cooling the inside of the furnace, the suction is performed by driving the suction exhaust gas suction fan by fully opening the valve opening of the suction exhaust gas flow rate adjusting valve while the charging door and the extraction door are fully opened. The exhaust gas is sucked and discharged, the furnace pressure damper is fully opened, the air that has passed through the furnace pressure damper is discharged from the chimney, the valve opening of the furnace tail exhaust gas flow control valve is fully opened, and the furnace tail exhaust gas is discharged. A cooling method for a continuous steel heating furnace, which comprises sucking and discharging air from the most downstream combustion control zone by driving a suction fan.

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