JP6953327B2 - How to operate the blast furnace shaft blowing device and the blast furnace shaft blowing device - Google Patents

Description

The present invention relates to a blast furnace shaft blowing device and a method of operating the blast furnace shaft blowing device.

Blast furnaces are used to manufacture pig iron in the steel industry. "Environmentally friendly steelmaking process technology development (COURSE50)" is being promoted as a next-generation technology development aimed at drastically reducing carbon consumption in blast furnace operation.
In COURSE50, _{as one of the technologies for suppressing CO 2} emissions, other gases such as furnace top gas (BFG) or coke oven gas (COG) recovered from the blast furnace are heated to the shaft of the blast furnace as reducing gas. It has been proposed to promote the reduction reaction of iron in the blast furnace by supplying it (Patent Document 1).

In Patent Document 1, in blast furnace operation, coke and the like are reduced by having hydrogen contained in a large amount in other gases such as furnace top gas (BFG) or coke furnace gas (COG) of the blast furnace take on the reducing material function. be. However, since the reduction reaction with hydrogen is an endothermic reaction, increasing the amount of hydrogen flowing into the blast furnace causes a shortage of heat in the blast furnace.
Therefore, in Patent Document 1, it is possible to solve the above-mentioned problem of insufficient heat quantity and significantly reduce _{CO 2} emissions by raising the temperature of the furnace top gas to 600 ° C. or higher and 1000 ° C. or lower to supplement the calorific value. It is supposed to be.

Japanese Unexamined Patent Publication No. 2015-129325

In order to realize stable commercial operation in the next-generation high-efficiency blast furnace operation as described in Patent Document 1, a large amount of reducing gas such as furnace top gas is heated to raise the temperature of the blast furnace in a high-pressure state. A device that stably supplies the shaft portion is required.
As such a device, a hot air furnace usually used for supplying hot air to a blast furnace can be considered.
However, in the hot air furnace, the combustion exhaust gas generated in the combustion process remains in the hot air furnace. Then, when the process is switched to the ventilation process, the residual combustion exhaust gas is supplied to the blast furnace. Here, since the combustion exhaust gas has already been burned and oxidized, it has almost no reducing agent function. Therefore, when such combustion exhaust gas is mixed with the reducing gas and supplied to the blast furnace, the reducing material function of the reducing gas is deteriorated, and the iron content reduction reaction in the blast furnace is suppressed.

An object of the present invention is an operation method of a blast furnace shaft blowing device and a blast furnace shaft blowing device capable of raising a large amount of reducing gas and supplying it to the shaft portion of the blast furnace without interfering with the iron reduction reaction in the blast furnace. To provide.

The operation method of the blast furnace shaft blowing device of the present invention is a method of operating the blast furnace shaft blowing device in which the reducing gas is heated by a plurality of hot air furnaces and supplied to the shaft portion of the blast furnace. A blowing step of raising the temperature of the reducing gas and supplying it to the shaft portion of the blast furnace, a combustion step of burning the fuel gas to store heat, and a replacement step of replacing the combustion exhaust gas remaining in the hot blast furnace with the reducing gas. It is characterized by having.

In the present invention, the reducing gas is heated by a plurality of hot air furnaces and supplied to the shaft portion of the blast furnace. Therefore, a large amount of reducing gas can be stably supplied to the shaft portion in a high temperature and high pressure state, and a highly efficient commercial operation of a blast furnace capable of significantly reducing _{CO 2 emissions becomes possible.}
Here, in the hot air furnace, the combustion exhaust gas generated in the combustion process remains in the hot air furnace. Therefore, if the blowing process is switched to in this state, the residual combustion exhaust gas is sent to the blast furnace. Then, the combustion exhaust gas is mixed with the reducing gas and supplied to the blast furnace, and the reducing material function of the reducing gas deteriorates. Therefore, the iron reduction reaction in the blast furnace is suppressed.
However, in the present invention, since the inside of the hot air furnace is replaced with the reducing gas after the combustion step, it is possible to prevent the combustion exhaust gas from being mixed with the reducing gas in the blowing step. Therefore, the reducing gas can be supplied to the blast furnace without deteriorating the function of the reducing agent, and it is possible to prevent the reduction reaction of iron in the blast furnace from being suppressed.

In the operation method of the blast furnace shaft blowing device of the present invention, in the replacement step, the pressure in the hot blast furnace is adjusted to be lower than the supply pressure of the reduction gas, and the reduction gas is transferred from the hot blast furnace to the shaft portion of the blast furnace. It is preferable that the reduced gas flows back into the hot blast furnace from the reduced gas supply line for supplying the gas.

In the present invention, since the pressure in the hot air furnace is adjusted to be lower than the supply pressure of the reducing gas in the replacement step, the reduced gas heated to a high temperature can flow back into the hot air furnace from the reducing gas supply line.
Therefore, in the replacement step, the reduced gas whose temperature has been raised from the reducing gas supply line can be introduced into the hot air furnace. Then, since the temperature in the hot blast furnace hardly changes between the combustion step and the replacement step, the temperature of the refractory refractory such as the refractory bricks piled up in the hot blast furnace also hardly changes. Therefore, it is possible to prevent the refractory of the hot blast furnace from becoming unstable due to temperature changes.

In the operation method of the blast furnace shaft blowing device of the present invention, it is preferable to increase the pressure of the fuel gas supplied into the hot air furnace in the combustion step.
In the present invention, in the combustion step, the fuel gas supplied to the hot blast furnace is boosted so that the inside of the hot blast furnace can have a sufficiently high pressure.
Here, when the combustion step is performed at atmospheric pressure (normal pressure) as in a conventional hot blast furnace, the difference between the blowing pressure of the reducing gas supplied to the blast furnace and the pressure in the hot blast furnace becomes large. Therefore, when the reducing gas is attempted to flow back into the hot air furnace from the reducing gas supply line, the reducing gas is rapidly introduced into the hot air furnace. Then, the flow rate of the reducing gas supplied to the blast furnace becomes unstable, and the reduction reaction of iron in the blast furnace is suppressed.

On the other hand, in the present invention, the pressure in the hot air furnace during the combustion process can be sufficiently increased. Therefore, it is possible to adjust the difference between the pressure in the hot air furnace during the combustion process and the pressure at which the reducing gas is blown. Then, by slightly lowering the pressure in the hot air furnace after the combustion process is completed, the flow rate of the reducing gas can be adjusted from the reducing gas supply line, and it is possible to prevent the reduced gas from being suddenly introduced. .. Therefore, it is possible to prevent the supply amount of the reducing gas to the blast furnace from becoming unstable.

Further, in the conventional hot blast furnace, when switching from the combustion process to the blasting process, a pressure equalizing operation is performed to increase the pressure in the hot blast furnace, and when switching from the blasting process to the combustion process, an exhaust pressure operation is performed. The pressure in the hot air furnace was reduced. However, in the present invention, since the pressure difference in the hot blast furnace is eliminated between the combustion step and the blasting step, the pressure equalizing operation and the exhaust pressure operation are not required, and each operation can be eliminated. Therefore, each work process can be reduced, and work efficiency and work cost can be reduced.

The blast furnace shaft blowing device of the present invention is a blast furnace shaft blowing device in which the reduction gas is heated by a plurality of hot air furnaces and supplied to the shaft portion of the blast furnace. It has a reduction gas supply line to be supplied, a combustion exhaust gas discharge line for discharging combustion exhaust gas from the blast furnace, and a pressure adjusting device installed in the combustion exhaust gas discharge line to adjust the pressure in the blast furnace. It is a feature.

In the present invention, by performing the same replacement step as the operation method of the blast furnace shaft blowing device described above, the combustion exhaust gas remaining in the hot blast furnace is burned while the reduced gas flows back into the hot blast furnace from the reduction gas supply line. It can be discharged to the gas discharge line. Therefore, the inside of the hot air furnace can be replaced with the reducing gas, and it is possible to prevent the combustion exhaust gas from being mixed in the reducing gas supplied to the blast furnace. Therefore, the reducing gas can be supplied to the blast furnace without deteriorating the function of the reducing agent, and it is possible to prevent the reduction reaction of iron in the blast furnace from being suppressed.

Here, in order to replace the hot air furnace with the reduction gas, a emission line is branched from the reduction gas supply line through which the reduction gas flows, a pressure adjusting device is provided in the emission line, and a pressure adjusting device is provided from the emission line. It is also conceivable to release the combustion exhaust gas remaining in the hot air furnace through the hot air furnace. However, in this case, since the reduced gas heated to a high temperature flows through the reducing gas supply line, it is necessary to adopt a special temperature specification having extremely high heat resistance for the pressure adjusting device installed in the emission line. be. Then, such a pressure regulator having a special temperature specification is expensive, and the structure is complicated and defects are likely to occur, so that the reliability of the equipment is impaired.
On the other hand, in the present invention, since the pressure adjusting device is provided in the combustion exhaust gas discharge line through which the relatively low temperature combustion exhaust gas flows, it is not necessary to adopt a pressure adjusting device having a special temperature specification having extremely high heat resistance, which is general. High temperature specifications can be adopted. A general pressure regulator with high temperature specifications is inexpensive, and the structure is not complicated and defects are unlikely to occur. Therefore, the equipment cost can be reduced and the reliability of the equipment can be improved.

In the blast furnace shaft blowing device of the present invention, it is preferable to have a booster for boosting the fuel gas supplied into the hot air furnace.
In the present invention, since the booster for boosting the fuel gas is provided, the same effect as the operation method of the blast furnace shaft blowing device described above can be expected.

In the blast furnace shaft blowing device of the present invention, the pressure adjusting device is preferably a pressure adjusting valve.
In the present invention, since the pressure adjusting device is a pressure adjusting valve, it can be easily attached to the combustion exhaust gas discharge line.
Further, if a complicated and expensive device such as an exhaust recovery device is adopted as the pressure adjusting device, the equipment cost becomes high and maintenance becomes difficult. However, since the pressure adjusting valve is adopted in the present invention, the equipment cost is reduced. It can be done and maintenance is easy.

In the blast furnace shaft blowing device of the present invention, it is preferable to have a replacement completion detection device that detects that the inside of the hot air furnace has been replaced with the reducing gas.
In the present invention, since it can be determined by the replacement completion detection device that the inside of the hot air furnace has been replaced with the reducing gas, the combustion exhaust gas remaining in the hot air furnace can be reliably replaced with the reducing gas. Therefore, it is possible to reliably prevent the combustion exhaust gas from being mixed with the reducing gas.

In the blast furnace shaft blowing device of the present invention, the replacement completion detection device is preferably any one of a flow meter, a gas analyzer, a timer, or a combination thereof.
In the present invention, since the replacement completion detection device is any one of a flow meter, a gas analyzer, and a timer, or a combination thereof, the flow meter and the gas analyzer can be easily attached to the combustion exhaust gas discharge line, and the timer can be used. It can be easily installed in a device that controls a blast furnace shaft blowing device.

According to the present invention, a method of operating a blast furnace shaft blowing device and a blast furnace shaft blowing device capable of raising a large amount of reducing gas and supplying it to the shaft portion of the blast furnace without interfering with the iron reduction reaction in the blast furnace. Can be provided.

The figure which shows the process flow of a hot blast furnace apparatus. The schematic which shows the operation cycle of a hot blast furnace apparatus. A flowchart showing a switching procedure when switching from a combustion process to a blowing process. The schematic diagram which shows the situation which one hot air furnace is executing a combustion process. The schematic diagram which shows the situation which one hot air furnace adjusts the pressure in a replacement process. The schematic diagram which shows the situation which one hot air furnace introduces a reducing gas in a replacement process. The schematic diagram which shows the situation which one hot air furnace is stopped in a switching process. The schematic diagram which shows the situation which one hot blast furnace has started the operation in the switching process. The schematic diagram which shows the situation which the other hot air furnace is stopped in a switching process. The schematic diagram which shows the situation which the other hot-air furnace has started the combustion process.

In FIG. 1, the hot air furnace device 1 is the blast furnace shaft blowing device of the present invention, and the furnace top gas (BFG) recovered from the blast furnace 2 is heated to 800 ° C. or higher and used as a reduction gas in the shaft portion of the blast furnace 2. By supplying the iron, the iron content reduction reaction in the blast furnace 2 is promoted, and the CO ₂ emission amount in the blast furnace 2 is significantly reduced.
The blast furnace 2 is a commercial blast furnace, for example, a blast furnace having an internal volume of 3,000 m ³ and an iron output of about 6,600 t · pig / D.

In the blast furnace 2, a charging device (not shown) is installed at the top 21 of the furnace, and a charging material mainly composed of iron ore and coke is inserted. In the blast furnace 2, apart from the normal tuyere 22 into which hot air is blown, a plurality of tuyere 23 of the blast furnace shaft portion are arranged in the circumferential direction of the furnace body, and the annular pipe 24 and the reducing gas supply of the present invention are supplied to each of them. The blast furnace device 1 is connected via the reduction gas supply main 10 as a line.
When the reducing gas is supplied from the hot air furnace device 1, the reducing gas is distributed by the annular pipe 24 and blown into the shaft portion of the blast furnace 2 from the tuyere 23 of the blast furnace shaft portion.

A furnace top gas recovery line 3 for recovering the furnace top gas is connected to the furnace top 21 to the blast furnace 2.
The furnace top gas recovery line 3 removes the BFG by taking out the BFG through the furnace top pipe 31 connected to the furnace top 21 and sequentially passing the BFG through a dust catcher (not shown) or the like.
The dust-removed BFG is recovered from residual energy such as pressure and heat by a furnace top pressure recovery facility (TRT) (not shown), converted into electric power, and reused.
The energy-recovered BFG is stored in the gas holder 32 and used as fuel for other equipment.

The hot air furnace device 1 includes two hot air furnaces 4 (4A, 4B). The hot air furnace 4 is a furnace top combustion type in which a combustion chamber 42 is arranged above the heat storage chamber 41.
The heat storage chamber 41 is loaded with checker bricks for heat storage, communicates with the combustion chamber 42 arranged above, and has a blower pipe 43 and a flue pipe 44 as a combustion exhaust gas discharge line of the present invention at the bottom of the furnace. It is connected.
A reduction gas supply pipe 45 is connected to the lower part of the combustion chamber 42, and an air supply pipe 46 and a fuel gas supply pipe 47 are connected to the furnace top burner portion.

The BFG supply line 5 is a pipe that supplies the furnace top gas (BFG) recovered from the blast furnace 2 to the hot air furnace device 1 as a reducing gas to be supplied to the blast furnace 2.
In the BFG supply line 5, the branch pipe 51 is connected to the downstream side of the furnace top pressure recovery facility (not shown) of the furnace top gas recovery line 3. Then, the BFG taken out from the portion is _{reformed by removing CO 2} and water vapor by the pretreatment device 52, and then supplied to the blower main 6.

The blower main 6 is connected to the blower pipe 43 and supplies the BFG supplied from the BFG supply line 5 as a reducing gas to the hot air furnace 4, and has a blower valve 431 at the connecting portion.
A reducing gas blower 61 is installed in the blower main 6, and the BFG supplied from the BFG supply line 5 is boosted to a predetermined pressure. Then, a predetermined pressure and flow rate of the BFG are adjusted by the blow pressure adjusting valve 62 and the blow flow rate adjusting valve 63, and the BFG is sent to the heat storage chamber 41 as a reducing gas. Therefore, the pressure in the heat storage chamber 41 and the combustion chamber 42 during the blowing process is maintained at a predetermined high pressure, and the reducing gas can be blown from the tuyere 23 of the blast furnace shaft portion even if the inside of the blast furnace 2 is high pressure.

The flue main 7 is a pipe that discharges the combustion exhaust gas generated in the hot air furnace 4, and connects the flare stack 71 that detoxifies and discharges the combustion exhaust gas to the flue pipe 44.
The flue pipe 44 is provided with a flue valve 441, a combustion exhaust gas flow meter 442 (442A, 442B), and a combustion pressure adjusting valve 443 as the pressure adjusting device of the present invention. The heat storage chamber 41 and the combustion chamber 42 are maintained at a predetermined pressure.

The fuel gas supply main 8 is a pipe for supplying fuel gas to the hot air furnace 4, and has a fuel gas supply valve 471 at a connection portion with the fuel gas supply pipe 47. As the fuel gas, a furnace top gas (BFG), a coke oven gas (COG), or the like recovered from the blast furnace 2 is used.
A fuel gas blower 81 is installed in the fuel gas supply main 8 as a booster of the present invention, and the fuel gas sent to the combustion chamber 42 is boosted to a predetermined pressure by the fuel gas blower 81. Therefore, the pressure in the combustion chamber 42 and the heat storage chamber 41 during the combustion operation can be increased to a predetermined pressure.

The air supply main 9 is connected to the air supply pipe 46 and is a pipe for supplying combustion air to the hot air furnace 4, and has an air supply valve 461 at the connecting portion.
When the pressure of the fuel gas supplied from the fuel gas supply main 8 to the combustion chamber 42 is increased, it is necessary to increase the pressure of the air supplied from the air supply main 9 to the combustion chamber 42 in order to balance the fuel. be. Therefore, a compressor 91 is installed in the air supply main 9 so that air can be pumped to the combustion chamber 42.

The reduction gas supply main 10 is a pipe that connects the reduction gas supply pipe 45 and the annular pipe 24 and supplies the reduction gas heated by the hot air furnace 4 to the blast furnace 2, and is a connection portion with the reduction gas supply pipe 45. It has a reduction gas supply valve 451.

FIG. 2 shows the operation cycle of the hot air furnace device 1.
As shown in FIG. 2, in the hot air furnace device 1 of the present embodiment, the two hot air furnaces 4 (4A, 4B) are made to alternately execute the combustion step S1 and the blowing step S4.
At this time, if the combustion step S1 is switched to the blowing process S4 as it is, the combustion exhaust gas remains in the hot air furnace 4, so that the combustion exhaust gas is mixed with the reducing gas. Then, the function of the reducing agent of the reducing gas is lowered, and the iron content reduction reaction in the blast furnace 2 is suppressed.
Therefore, in the present embodiment, when switching from the combustion step S1 to the blowing step S4, the replacement step S2 for replacing the combustion exhaust gas remaining in the hot air furnace 4 with the reducing gas is carried out.

FIG. 3 shows a flowchart showing a procedure in which the two hot air furnaces 4 (4A, 4B) switch from the combustion process S1 to the air blowing process S4.
As shown in FIG. 3, in the replacement step S2, an operation for lowering the pressure in the hot air furnace 4 (pressure adjustment S21) and then introducing the reducing gas into the hot air furnace 4 from the reducing gas supply main 10 is performed. (Introduction operation S22). Then, the reducing gas flowing through the reducing gas supply main 10 flows back into the hot air furnace 4 (backflow S23). Then, when it is confirmed that the inside of the hot air furnace 4 has been replaced with the reducing gas (replacement completion S24), the replacement step S2 is completed.
The details of the operation state when switching from the combustion process S1 to the ventilation process S4 will be described below.

4 to 10 show an operating state when the hot air furnace 4A switches from the combustion process S1 to the blowing process S4 and an operating state when the hot air furnace 4B switches from the blowing process S4 to the combustion process S1.
Here, in FIGS. 4 to 10, the valves described in white indicate the open state, and the valves described in black are shown in the closed state. Further, in the hot air furnaces 4A and 4B, the inside is hatched in a grid pattern indicates that the combustion exhaust gas is present inside, and the inside is hatched with diagonal lines because the reducing gas is inside. Indicates an existing situation.

First, FIG. 4 shows a situation in which the hot air furnace 4A is executing the combustion step S1.
As shown in FIG. 4, in the hot air furnace 4A in the situation where the combustion step S1 is being executed, the flue valve 441A, the fuel gas supply valve 471A and the air supply valve 461A are opened, and the blow valve 431A and the reduction gas supply valve 451A are opened. Is closed. That is, the hot air furnace 4A is communicated with the flue main 7, the fuel gas supply main 8, and the air supply main 9, and the connection between the flue main 6 and the reduction gas supply main 10 is cut off. ..

In this situation, the fuel gas boosted by the fuel gas blower 81 is supplied to the top burner portion of the hot air furnace 4A through the fuel gas supply pipe 47A.
Further, the air boosted by the compressor 91 is supplied from the air supply main 9 to the furnace top burner portion of the hot air furnace 4A through the air supply pipe 46A.
Then, the fuel gas and air supplied to the furnace top burner portion are mixed and burned in the combustion chamber 42A. That is, unlike the normal hot air furnace, the hot air furnace 4A burns fuel gas and air in a high pressure state. Then, the checkered bricks arranged in the heat storage chamber 41A are stored in heat by the combustion of the fuel gas and the combustion air.

The combustion exhaust gas generated in the combustion chamber 42A is discharged to the flue main 7 through the flue pipe 44A, and finally detoxified by the flare stack 71 and discharged. At this time, the pressure of the combustion exhaust gas flowing through the flue pipe 44A is adjusted to a predetermined pressure P1 by the combustion pressure adjusting valve 443A. The predetermined pressure P1 is adjusted to, for example, about 0.5 MPa. Therefore, the pressure in the combustion chamber 42A and the heat storage chamber 41A of the hot air furnace 4A communicating with the flue pipe 44A is maintained at a predetermined pressure P1.

Further, while the hot air furnace 4A is executing the combustion step S1, the hot air furnace 4B is executing the blowing process S4. In the situation where the hot air furnace 4B is executing the blowing step S4, the blowing valve 431B and the reducing gas supply valve 451B are opened, and the flue valve 441B, the fuel gas supply valve 471B, and the air supply valve 461B are closed. That is, the hot air furnace 4B is communicated with the blower main 6 and the reduction gas supply main 10, and the connection with the flue main 7, the fuel gas supply main 8 and the air supply main 9 is cut off. ..

In this situation, the BFG boosted by the reducing gas blower 61 is adjusted to a predetermined pressure and flow rate by the blowing pressure adjusting valve 62 and the blowing flow rate adjusting valve 63, and is supplied as the reducing gas to the heat storage chamber 41B through the blower pipe 43B. NS.
At this time, the blowing pressure adjusting valve 62 is adjusted so that the blowing pressure of the reducing gas becomes a predetermined pressure P1. Therefore, the pressure in the combustion chamber 42B and the heat storage chamber 41B of the hot air furnace 4B in the blowing step S4 is maintained at a predetermined pressure P1. That is, the pressure in the hot air furnace 4A in the combustion step S1 and the hot air furnace 4B in the blowing process S4 are adjusted to P1 and become approximately equal.
The reducing gas supplied to the heat storage chamber 41B of the blast furnace 4B is heated by the checker brick, supplied to the annular pipe 24 through the reducing gas supply pipe 45B and the reducing gas supply main 10, and distributed by the annular pipe 24. It is blown into the shaft portion of the blast furnace 2 from the tuyere 23 of the blast furnace shaft portion.

In the hot air furnace 4A, when the combustion step S1 is executed for a predetermined time, the combustion step S1 is completed and the process shifts to the replacement step S2.
FIG. 5 shows an operating state in which the pressure adjustment S21 is executed in the replacement step S2 of the hot air furnace 4A. At this time, the hot air furnace 4B continues the blowing process S4.
As shown in FIG. 5, in the situation where the hot air furnace 4A is executing the pressure adjustment S21, the fuel gas supply valve 471A and the air supply valve 461A are closed, and the hot air furnace 4A, the fuel gas supply main 8 and the air supply main are closed. The connection with the pipe 9 is cut off. Therefore, fuel gas and air are not supplied to the hot air furnace 4A, and combustion in the combustion chamber 42A is stopped.

Further, the combustion exhaust gas remaining in the combustion chamber 42A and the heat storage chamber 41A is discharged to the flue main 7 through the flue pipe 44A. At this time, the pressure of the combustion exhaust gas flowing through the flue pipe 44A is adjusted by the combustion pressure adjusting valve 443A so as to be a predetermined pressure P2 slightly lower than P1. Therefore, in the pressure adjustment S21, the pressure in the combustion chamber 42A and the heat storage chamber 41A of the hot air furnace 4A is adjusted to P2. Here, the predetermined pressure P2 is adjusted to a pressure lower than, for example, P1 by about 10 to 20 KPa. Then, when the pressure of the combustion exhaust gas is adjusted to P2, the reduction gas supply valve 451A is opened (introduction operation S22) to allow the reduction gas to flow back into the hot air furnace 4A (backflow S23).

Next, FIG. 6 shows a situation in which the reducing gas is flowing back into the hot air furnace 4A (backflow S23).
As shown in FIG. 6, in a situation where the reduction gas is flowing back into the hot air furnace 4A, the reduction gas supply valve 451A of the reduction gas supply pipe 45A is opened, and the hot air furnace 4A and the reduction gas supply main 10 are communicated with each other. NS. Here, since the pressure in the hot air furnace 4A is adjusted to P2 by the combustion pressure adjusting valve 443A, it is slightly lower than the pressure P1 in the hot air furnace 4B. Therefore, the reducing gas blown by the hot air furnace 4B flows back into the hot air furnace 4A via the reducing gas supply main 10 and the reducing gas supply pipe 45A. Then, the combustion exhaust gas remaining in the hot air furnace 4A is discharged to the flue main pipe 7 through the flue pipe 44A. That is, the combustion exhaust gas is discharged and replaced by the backflow of the reducing gas flowing through the reducing gas supply main 10 in the hot air furnace 4A.

At this time, since the pressure difference between the pressure P2 in the hot air furnace 4A and the pressure P1 in the hot air furnace 4B is small, the reducing gas blown from the hot air furnace 4B does not suddenly flow back into the hot air furnace 4A. , The inside of the hot air furnace 4A is gradually replaced with the reducing gas. Therefore, it is possible to prevent the flow rate of the reducing gas blown into the blast furnace 2 from becoming unstable.
Further, since a part of the reducing gas supplied from the hot air furnace 4B to the blast furnace 2 flows back into the hot air furnace 4A, the flow rate of the reducing gas supplied to the blast furnace 2 is reduced by that amount. Therefore, in order to maintain the blowing flow rate of the reducing gas supplied to the blast furnace 2, the blowing flow rate of the reducing gas supplied to the hot air furnace 4B is adjusted by the blowing flow rate adjusting valve 63. At that time, the flow rate of the combustion exhaust gas discharged from the inside of the hot air furnace 4A is detected by the combustion exhaust gas flow meter 442A, and the flow rate supplied to the hot air furnace 4B is increased by the amount of the flow rate detected by the combustion exhaust gas flow meter 442A. For example, when the detected value of the combustion exhaust gas flow meter 442A is 10% of the blown amount, the blown flow rate of the reducing gas is increased by 10% and adjusted by the blown flow rate adjusting valve 63 so as to be 110%.

Then, when the integrated value of the combustion exhaust gas flow rate detected by the combustion exhaust gas flow meter 442A reaches a predetermined value, it is determined that the inside of the hot air furnace 4A has been replaced with the reducing gas (replacement completion S24), and the replacement step S2 is completed. .. That is, the combustion exhaust gas flow meter 442A also acts as a replacement completion detection device. At this time, the predetermined value of the integrated value of the combustion exhaust gas flow rate is set to be equal to or larger than the volume in the hot air furnace 4A. As a result, it can be determined that the combustion exhaust gas corresponding to the volume in the hot air furnace 4A has been discharged, so that it can be determined that the inside of the hot air furnace 4A has been replaced by the reducing gas. Then, when the replacement step S2 is completed, the process proceeds to the switching step S3.

In the switching step S3, first, as shown in FIG. 7, all the valves other than the reduction gas supply valve 451A of the hot air furnace 4A are temporarily closed, and the operation is stopped. Next, as shown in FIG. 8, the blow valve 431A is opened, and the blow step S4 of the hot air furnace 4A is started. Then, the reduced gas boosted by the reducing gas blower 61 is supplied to the heat storage chamber 41A via the blower pipe 43A. The reduction gas supplied to the heat storage chamber 41A is heated by the checker bricks and supplied to the shaft portion of the blast furnace 2 through the reduction gas supply pipe 45A and the reduction gas supply main pipe 10.
When the blowing of the reducing gas is started in the hot air furnace 4A, as shown in FIG. 9, all the valves of the hot air furnace 4B are once closed and the operation is stopped.

After that, as shown in FIG. 10, the flue valve 441B, the fuel gas supply valve 471B, and the air supply valve 461B are opened, so that the fuel gas and the combustion air pass through the fuel gas supply pipe 47B and the air supply pipe 46B and hot air. It is supplied to the top burner portion of the furnace 4B, and the combustion step S1 is started in the combustion chamber 42B. Then, the combustion exhaust gas generated in the combustion chamber 42B is discharged to the flue main 7 through the flue pipe 44B. At this time, the pressure of the combustion exhaust gas flowing through the flue pipe 44B is adjusted to a predetermined pressure P1 by the combustion pressure adjusting valve 443B.
Through such a switching step S3, the blowing step S4 is started in the hot air furnace 4A, and the combustion step S1 is started in the hot air furnace 4B.

Returning to FIG. 2, the two blast furnaces 4 (4A, 4B) alternately repeat the combustion step S1 and the blowing step S4 in the above-mentioned procedure, so that the reduced gas is heated without mixing the combustion exhaust gas. Can be continuously supplied to the blast furnace 2.

As described above, according to the hot air furnace device 1 of the present embodiment, the following effects can be obtained.
In the present embodiment, since the hot air furnace device 1 is adopted as a device for raising the temperature of the furnace top gas (BFG) recovered from the blast furnace 2 to 800 ° C. or higher, the temperature of the furnace top gas (BFG) is raised in a large amount and reduced. As gas, it can be stably supplied to the shaft portion of the blast furnace 2 in a high pressure state. Therefore, commercial operation of the highly efficient blast furnace 2 capable of significantly reducing _{CO 2 emissions becomes possible.}

In the present embodiment, by executing the replacement step S2, the combustion exhaust gas generated in the combustion step S1 is replaced with the reducing gas, so that it is possible to prevent the combustion exhaust gas from being mixed with the reducing gas in the blowing step S4. Therefore, the reducing gas can be supplied to the blast furnace 2 without deteriorating the function of the reducing agent, and it is possible to prevent the reduction reaction of iron from being suppressed.

Further, as a pressure adjusting device for adjusting the pressure in the hot air furnace 4, a combustion pressure adjusting valve 443 is installed in the flue pipe 44. Since the combustion exhaust gas discharged to the flue pipe 44 is deprived of heat by the checker bricks installed in the heat storage chamber 41 in the hot air furnace 4, the temperature is usually lowered to about 300 ° C.
Here, in order to replace the inside of the hot air furnace 4 with the reducing gas, for example, a emission line is branched from the reducing gas supply main 10 through which the reducing gas flows, and a pressure adjusting valve is provided in the emission line to dissipate the gas. It is also conceivable to discharge the combustion exhaust gas remaining in the hot air furnace 4 from the line via the pressure regulating valve. In this case, since the reducing gas heated to 800 ° C. or higher flows through the emission line, it is necessary to adopt a special temperature specification having extremely high heat resistance for the pressure regulating valve installed in the emission line. Then, such a pressure control valve having a special temperature specification is expensive, and the structure is complicated and defects are likely to occur, so that the reliability of the equipment is impaired.
On the other hand, in the present embodiment, since the combustion pressure adjusting valve 443 is installed in the flue pipe 44 through which the relatively low temperature combustion exhaust gas flows, a general high temperature specification is adopted for the combustion pressure adjusting valve 443. can. A general pressure regulating valve with high temperature specifications is inexpensive, has a complicated structure, and is less likely to cause a problem. Therefore, equipment cost can be reduced and equipment reliability can be improved.

Further, in the replacement step S2, the reduced gas heated to a high temperature is made to flow back into the hot air furnace 4, so that the temperature in the hot air furnace 4 hardly changes between the combustion step S1 and the replacement step S2. Therefore, the temperature of the refractory refractory such as refractory bricks piled up in the refractory 4 hardly changes, and the destabilization of the refractory refractory due to the temperature change can be prevented.

In the present embodiment, in the combustion step S1, the fuel gas supplied to the hot air furnace 4 is boosted by the fuel gas blower 81 and supplied to the combustion chamber 42, so that the pressure in the hot air furnace 4 is increased to a predetermined pressure P1. can do.
Here, when the combustion step S1 is performed at atmospheric pressure (normal pressure) as in the conventional hot blast furnace, the difference between the blowing pressure of the reducing gas supplied to the blast furnace 2 and the pressure in the hot blast furnace 4 becomes large. Therefore, if the reducing gas flows back in the same state, the reducing gas is rapidly introduced into the hot air furnace 4. Then, the flow rate of the reducing gas supplied to the blast furnace 2, including the backflow from the blast furnace 2, becomes unstable, and the reduction reaction of iron in the blast furnace 2 is suppressed.
On the other hand, in the present embodiment, the pressure in the hot air furnace 4 can be adjusted to P2 slightly lower than P1 by the combustion pressure adjusting valve 443, so that the pressure in the hot air furnace 4 is supplied to the pressure P2 and the blast furnace 2. The pressure difference between the reducing gas blowing pressure and P1 can be reduced. Therefore, it is possible to prevent the reducing gas from being suddenly introduced into the hot air furnace 4, and the flow rate of the reducing gas supplied to the blast furnace 2 becomes unstable when the replacement step S2 is being executed. Can be suppressed.

Further, in the conventional hot air furnace, in the switching step S3, the pressure equalizing operation is performed to increase the pressure in the hot air furnace, or the exhaust pressure operation is performed to decrease the pressure in the hot air furnace. However, in the present embodiment, since the pressure difference in the hot air furnace 4 is eliminated between the combustion process S1 and the ventilation process S4, it is not necessary to perform the pressure equalizing operation and the exhaust pressure operation in the switching process S3, and each operation is eliminated. Can be done. Therefore, each work process can be reduced, and work efficiency and work cost can be reduced.

Further, in the present embodiment, in the replacement step S2, the amount of combustion exhaust gas discharged from the hot air furnace 4 is detected by the combustion exhaust gas flow meter 442, and the reduced gas supplied to the blast furnace 2 by the amount of the discharged combustion exhaust gas flow rate is blown. Increase the flow rate. Therefore, even when the reducing gas is introduced into the hot air furnace 4, the flow rate of the reducing gas supplied to the blast furnace 2 does not change, and the iron content reduction reaction in the blast furnace 2 can be stably maintained.
Further, when the integrated value of the combustion exhaust gas flow rate detected by the combustion exhaust gas flow meter 442 reaches a predetermined amount, it is determined that the inside of the hot air furnace 4A has been replaced with the reducing gas (replacement completion S24). In this way, since the combustion exhaust gas flow meter 442 also acts as a replacement completion detection device, the combustion exhaust gas remaining in the hot air furnace 4 can be reliably replaced with the reducing gas. At that time, by setting the predetermined amount of the integrated value of the combustion exhaust gas amount to be equal to or larger than the volume in the hot air furnace 4, it can be determined that the combustion exhaust gas amount corresponding to the volume in the hot air furnace 4 is discharged.

The present invention is not limited to the above-described embodiment, and modifications within the range in which the object of the present invention can be achieved are included in the present invention.
For example, the number of hot air furnaces 4 installed in the hot air furnace device 1 is not limited to two, and may be three or more. For example, when there are three hot air furnaces 4, the combustion step S1 described above can be executed for each of the two, and one of them is suspended, and the combustion process S1 and the blowing process S4 are alternately and repeatedly executed by the two. You may do so.

In the above embodiment, in the replacement step S2, the reduced gas flowing through the reducing gas supply main 10 via the reducing gas supply pipe 45 is made to flow back into the hot air furnace 4, so that the combustion exhaust gas remaining in the hot air furnace 4 is removed. The inside of the hot air furnace 4 was replaced with the reducing gas by discharging the gas to the flue main 7, but another replacement method may be used as long as the inside of the hot air furnace 4 can be replaced with the reducing gas.
For example, by providing a emission line in the reduction gas supply main 10 and providing a pressure adjusting valve in the emission line, hot air is allowed to flow into the hot air furnace 4 through the blower pipe 43 and hot air is provided through the emission line. The combustion exhaust gas remaining in the furnace 4 may be discharged.
However, as described above, since the reducing gas heated to 800 ° C. or higher is circulated in the reducing gas supply main 10, the emission line is expensive with a special temperature specification having heat resistance of 800 ° C. or higher. It is necessary to install a pressure control valve, which increases the equipment cost. Therefore, as in the above embodiment, the combustion pressure adjusting valve 443 is provided in the flue pipe 44 through which the relatively low temperature combustion exhaust gas flows, and the reducing gas flowing through the reducing gas supply main 10 is made to flow back to hot air. It is preferable to adopt a method of replacing the inside of the furnace 4.

In the above embodiment, the hot air furnace 4 is a furnace top combustion type, but it may be an external combustion type or an internal combustion type, and the type is not limited.
Further, by increasing the fuel gas and air sent to the combustion chamber 42 of the hot air furnace 4 to a predetermined pressure, the combustion step S1 is usually executed with the pressure inside the hot air furnace 4 increased. The combustion step S1 may be executed at an atmospheric pressure (normal pressure) as in the hot air furnace of the above.
However, in this case, in the replacement step S2, the pressure difference between the blowing pressure of the reducing gas and the pressure in the hot air furnace 4 becomes large, so that the reducing gas is rapidly introduced into the hot air furnace 4. Then, the flow rate of the reducing gas supplied to the blast furnace 2 becomes unstable, and the reduction reaction of iron in the blast furnace 2 is suppressed. Further, in order to prevent such a phenomenon, it is conceivable to execute a pressure equalizing operation for increasing the pressure in the hot air furnace 4 after the combustion step S1, but this makes the operation work complicated. Further, since it is necessary to carry out the exhaust pressure operation in the switching step S3 for switching from the blowing step S4 to the combustion step S1, the work efficiency is lowered. Therefore, it is preferable to execute the combustion step S1 in a state where the pressure in the hot air furnace 4 is increased as in the above embodiment.

In the above embodiment, the combustion pressure adjusting valve 443 is adopted as the pressure adjusting device of the present invention. For example, the exhaust pressure recovery equipment is installed in the flue pipe 44, and the pressure of the combustion exhaust gas is controlled by controlling the exhaust pressure recovery equipment. It may be adjusted, and a pressure adjusting device having another configuration may be used as long as it can adjust the pressure of the combustion exhaust gas passing through the flue pipe 44.
Further, the combustion exhaust gas flow meter 442 is adopted as the replacement completion detection device of the present invention. For example, a gas analyzer is installed in the flue pipe 44 and a hot air furnace is analyzed by analyzing the components of the gas passing through the flue pipe 44. It may be detected that the inside of the 4 is replaced with the reducing gas, or it may be detected by a timer that the reducing gas having only the body integral in the hot air furnace 4 has been introduced into the hot air furnace. If it can be determined that the residual combustion exhaust gas has been replaced with the reducing gas, a replacement completion detection device having another configuration may be used.

The present invention can be used for operating a blast furnace shaft blowing device and a blast furnace shaft blowing device.

1 ... hot air furnace device, 2 ... blast furnace, 21 ... furnace top, 22 ... tuyere, 23 ... blast furnace shaft part tuyere, 24 ... annular pipe, 3 ... furnace top gas recovery line, 31 ... furnace top piping, 32 ... gas holder , 4,4A, 4B ... Hot air furnace, 41, 41A, 41B ... Heat storage chamber, 42, 42A, 42B ... Combustion chamber, 43, 43A, 43B ... Blower pipe, 431, 431A, 431B ... Blower valve, 44, 44A, 44B ... flue pipe, 441, 441A, 441B ... flue valve, 442, 442A, 442B ... combustion exhaust gas flow meter, 443, 443A, 443B ... combustion pressure regulating valve, 45, 45A, 45B ... reduction gas supply pipe, 451, 451A, 451B ... Reduction gas supply valve, 46, 46A, 46B ... Air supply pipe, 461, 461A, 461B ... Combustion air valve, 47, 47A, 47B ... Fuel gas supply pipe, 471, 471A, 471B ... Fuel Gas supply valve, 5 ... Reduction gas supply line, 51 ... Branch pipe, 52 ... Pretreatment device, 6 ... Blower main, 61 ... Reduction gas blower, 62 ... Blow pressure control valve, 63 ... Blow flow control valve, 7 ... Smoke Road main, 71 ... flare stack, 8 ... fuel gas supply main, 81 ... fuel gas blower, 9 ... air supply main, 91 ... compressor, 10 ... reduction gas supply main.

Claims (8)

It is an operation method of a blast furnace shaft blowing device that raises the temperature of the reducing gas by a plurality of hot air furnaces and supplies it to the shaft portion of the blast furnace.
The hot air furnace has a blowing step of raising the temperature of the reducing gas and supplying it to the shaft portion of the blast furnace.
A combustion process that burns fuel gas to store heat,
Have a, a substitution process for replacing the combustion exhaust gas remaining in the hot air oven at the reducing gas,
In the replacement step of the hot blast furnace of one of the plurality of hot blast furnaces, the combustion exhaust gas remaining in the hot blast furnace is discharged to an apparatus other than the blast furnace via the combustion exhaust gas discharge line, and the replacement step is performed. It is characterized in that the combustion exhaust gas remaining in the hot blast furnace is replaced with the reduced gas by introducing the heated reduction gas supplied from the hot blast furnace different from the hot blast furnace being carried out. How to operate the blast furnace shaft blowing device. In the method of operating the blast furnace shaft blowing device according to claim 1,
In the replacement step , the pressure in the hot blast furnace in which the replacement step is carried out is adjusted to be lower than the supply pressure of the reducing gas, and the hot blast furnace different from the hot blast furnace in which the replacement step is carried out is performed. The blast furnace shaft blower is characterized in that the heated reduction gas is backflowed into the hot air furnace performing the replacement step from the reduction gas supply line that supplies the reduction gas to the shaft portion of the blast furnace. How to operate the blast furnace. In the method of operating the blast furnace shaft blowing device according to claim 1 or 2.
A method for operating a blast furnace shaft blowing device, which comprises boosting the fuel gas supplied into the hot air furnace in the combustion step. In a blast furnace shaft blowing device in which the reduction gas is heated by a plurality of hot air furnaces and supplied to the shaft portion of the blast furnace.
A reducing gas supply line that supplies the reducing gas from the hot air furnace to the shaft portion of the blast furnace, and
A combustion exhaust gas discharge line that discharges combustion exhaust gas from the hot air furnace,
Wherein installed in the flue gas discharge line have a, a pressure regulator for adjusting the pressure of the hot air furnace,
The pressure adjusting device adjusts the pressure in the hot air furnace to be lower than the supply pressure of the reducing gas, and adjusts the combustion exhaust gas remaining in the hot air furnace via the combustion exhaust gas discharge line to a device other than the blast furnace. A blast furnace shaft blowing device, characterized in that the inside of the hot blast furnace is replaced with the reduced gas by introducing the reduced gas whose temperature has been raised from the reduction gas supply line into the hot blast furnace. In the blast furnace shaft blowing device according to claim 4,
A blast furnace shaft blowing device characterized by having a booster for boosting the fuel gas supplied into the hot blast furnace. In the blast furnace shaft blowing device according to claim 4 or 5.
The blast furnace shaft blowing device, wherein the pressure adjusting device is a pressure adjusting valve. In the blast furnace shaft blowing device according to any one of claims 4 to 6.
Have a replacement completion detection device for detecting that the hot air furnace is replaced by the reducing gas,
The replacement completion detection device detects that the combustion exhaust gas remaining in the hot blast furnace is discharged through the combustion exhaust gas discharge line, thereby indicating that the inside of the hot blast furnace has been replaced with the reducing gas. A blast furnace shaft blowing device characterized by detection. In the blast furnace shaft blowing device according to claim 7.
The blast furnace shaft blowing device is characterized in that the replacement completion detection device is any one of a flow meter, a gas analyzer, a timer, or a combination thereof.

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