JP2003129119A - Method for feeding fuel gas into hot-blast stove - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for feeding gas into a hot-blast stove, which can prevent the gas from being burnt and dissipated into the atmospheric air, by increasing an average pumping quantity of converter gas to be fed into the hot-blast stove, and by increasing consumption of the converter gas. SOLUTION: One blast furnace 21 has three or more hot-blast stoves 14 for sending the hot air. Each of the hot-blast stoves 14 is repeatedly operated in sequential steps of burning, waiting, and air blasting, where the burning steps of two hot-blast stoves 14 partially overlap. When supplying each of the hot-blast stoves 14 with mixture gas of coke oven gas, blast furnace gas and converter gas as fuel gas, this method is characterized by reducing a mixing quantity of the coke oven gas, and increasing the mixing quantity of the converter gas, while keeping a colorific value per unit time for the fuel gas in the mixture gas, which is supplied to either or both of the two hot-blast stoves 14 that are burning in an overlapped time, to a predetermined value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention increases the average pumping amount of converter gas in the fuel gas supplied to a hot stove to reduce the pumping loss of the blower, and reduces the combustion emission of converter gas into the atmosphere. The present invention relates to a method for supplying fuel gas to a hot stove to prevent.

[0002]

2. Description of the Related Art As shown in FIG. 6, an integrated steel mill having a blast furnace has a coke oven 80 for carbonizing carbon to produce coke, the obtained coke and various raw materials (for example, iron ore, manganese ore, limestone). ) Is charged, for example, four hot-air stoves 8
1. A blast furnace 83 that supplies hot air generated in a hot blast stove 82 equipped with 1 from below to reduce iron ore to produce pig iron, and a converter 84 that produces oxygen by blowing oxygen into the obtained pig iron to produce molten steel. It is composed of various manufacturing equipment (not shown) for manufacturing various products having a predetermined shape from the obtained molten steel, and is further provided with utility equipment such as a private power plant 95 and a steam generating boiler 96. Then, a coke oven gas (hereinafter, referred to as COG) generated by the operation of the coke oven 80, a blast furnace gas (hereinafter, referred to as BFG) produced by the operation of the blast furnace 83, and an operation of the converter 84. The generated converter gas (hereinafter, referred to as LDG) is once accumulated in the dedicated gas holders 85, 86, 87 respectively to absorb the fluctuation of the gas generation amount and the fluctuation of the gas usage amount, and the dust collecting device 88, After being dusted at 89 and 90, the required pressure is maintained by blowers 91, 92 and 93, and the gas is supplied as fuel gas to each hot stove 81 through a gas supply facility 94. Further, some of the LDGs are supplied as fuel gas to the private power plant 95 and the steam generating boiler 96, which are gas-using factories, through the blower 93.

Here, COG and BFG can always be stably supplied because the coke oven 80 and the blast furnace 83 are always in operation and the stored amounts of the gas holders 85 and 86 installed therein are large. . In addition, since the composition of each gas is stable, COG is about 4500 kcal /
Nm ³ and BFG have a calorific value (gas calorie) of about 800 kcal / Nm ³ . On the other hand, the LDG is generated only when the converter 84 is operating, and the LDG generated in the initial stage of the refining start has a very low content of CO gas serving as a combustion source, and thus is emitted to the atmosphere from the diffusion tower 97, The content gradually increases and, for example, is accumulated in the gas holder 87 when the CO content reaches 40% or more. Therefore, the CO content of the LDG accumulated in the gas holder 87 fluctuates, and the gas calorie of the LDG is about 170.
It is 0 to 2200 kcal / Nm ³ .

As shown in FIG. 7, the hot-air stove 81 to which COG, BFG, and LDG are supplied is a heat-storage type heat exchange furnace, and the COG supplied from the gas supply equipment 94 through the valve 105. , BFG, and LDG mixed fuel gas and combustion air are mixed and burned in the combustion chamber 98 for a predetermined combustion time, and the generated heat heats the heat storage chamber 99. The air preheated to ˜250 ° C. is supplied from the blower pipe 100 for a predetermined time to cause heat exchange and the temperature is raised to a temperature at which the blast furnace 83 can be blown.
It is equipment to send to 3. Here, when the calorific value of the fuel gas per unit volume (mixed gas calorie) decreases, the flame temperature decreases and the dome 101 above the hot stove 81.
The temperature does not rise, the amount of exhaust gas increases and the thermal efficiency decreases. On the other hand, if the mix gas calorie increases, a delay in tracking the combustion air ratio occurs, incomplete combustion occurs, the flame temperature decreases, and the temperature of the dome 101 does not increase. Therefore, when the fluctuation of the mixed gas calorie is repeated many times, thermal stress is generated in the refractory bricks constituting the hot-air stove 81 due to the temperature fluctuation, and the life of the refractory bricks is also affected. It will be. Therefore, the fuel gas is supplied to the hot blast stove 81 so that the fuel gas in which COG, BFG, and LDG are mixed is supplied in a constant amount of heat per unit time so that the temperature of the dome 101 above the hot blast stove 81 does not change, and To ensure a stable supply of fuel gas under a constant calorific value,
A fuel gas calorimeter 102 for measuring the calorific value of the fuel gas,
COG according to the output signal from the fuel gas calorimeter 102,
Control device 1 for determining each mixing ratio of BFG and LDG
03, and a gas supply facility 9 including a gas supply facility main body 104 that mixes each gas according to a command from the control device 103.
It is done through 4.

Further, four hot blast furnaces 81 are provided for one blast furnace 83, for example, and each hot blast furnace 81 is repeatedly operated for about 80 minutes for combustion time and about 100 minutes for blowing time. There is. Therefore, in the hot air stove 81, it is not possible to blow air to the blast furnace 83 during the combustion time, and it is not possible to burn in the hot air stove 81 during the blowing time. Two hot blast stoves 81 are operated (combustion of two hot blast stoves 81), and when combustion is completed in one of the hot stove 81, another hot stove 81 is operated. When the combustion of one of the hot blast stoves 81 is ended and the other hot blast stove 81 is burned (hereinafter referred to as “replacement of the furnace”), the period of one combustion in which only the other hot blast stove 81 is operating Occurs. The switching between the one-unit combustion and the two-unit combustion is performed by opening and closing the valve 105, and the period for one-unit combustion is controlled by the gas supply facility 94 so that the combustion heat amount becomes 1/2 as compared with the period for two-unit combustion. Adjust the combustion gas supply amount of.

As shown in FIGS. 8A and 8B, the COG, BFG, and LDG gas flow rates are adjusted by the total amount of heat required in the two-unit combustion period and the one-unit combustion period, and It is performed based on the mixed gas calorie set value. In addition, since the calorific value of the LDG fluctuates in the order of time, adjustment of the mixed gas calorie is mainly performed for the BFG and the COG as shown in FIGS. COG, which has a high heat quantity and is stable, is the main subject of control. At this time, due to the characteristics of the orifice of the COG flowmeter provided in the gas supply facility 94, a measurement error becomes large at a flow rate of 10% or less of the maximum measurement value, and an error occurs in the calorific value calculation. ), The minimum value (MIN COG flow rate) is set for the amount of COG used. Next, regarding the amount of LDG mixed, FIG.
It is set by the ratio value to the BFG flow rate shown in (C). For example, the converter gas ratio (LDG ratio) is manipulated so as to meet the LDG balance in consideration of generation and use of LDG, for example, as shown in FIG. 8 (E). In addition,
In the operation of the LDG ratio, consideration is given so that the usage amount of COG does not reach the minimum value.

[0007]

Problems to be Solved by the Invention FIGS. 9 (A) and 9 (B)
Is, for example, in the first blast furnace side hot blast stove group (1HS) and the second blast furnace side hot blast stove group (2HS) when two blast furnaces 83 exist (hereinafter, referred to as first blast furnace and second blast furnace). It shows the control result of the flow rate of each gas. Figure 9
As shown in (A) and (B), COG, BFG, and L
In order to minimize the fluctuation of each gas balance of DG, operation is performed so that the periods of combustion of one unit in the first blast furnace side hot blast furnace group (1HS) and the second blast furnace side hot blast furnace group (2HS) do not overlap. . In FIGS. 9 (A) and 9 (B), reference numerals a,
The period indicated by B, C, D, and E is the period for one unit combustion. Further, FIG. 9 (C) shows the flow rate of the LDG pumped together for the first blast furnace side hot blast stove group (1HS) and the second blast furnace side hot blast stove group (2HS). At this time, the LDG ratio is the maximum pumping capacity of the blower 93 when the first blast furnace side hot blast stove group burns 2 units and the second blast furnace side hot blast stove group burns 2 units (in a period shown by ↓). It is set to approach. Therefore, the first blast furnace side hot blast stove group (1HS) and the second blast furnace side hot blast stove group (2H
In the period of S) of one unit combustion, the LDG flow rate is reduced by the flow rate determined by the LDG ratio with respect to the BFG flow rate, and a pumping loss occurs in the period shown by ↑, and the average pumping rate is considerably lower than the maximum pumping capacity. It was For this reason, when the amount of generated LDG increases with respect to the amount used, the amount of LDG becomes excessive and is burned and diffused into the atmosphere from the diffusion tower 97 as excess gas,
The effective use of heat energy was hindered. The present invention has been made in view of such circumstances, and it is possible to increase the average pumping amount of the converter gas supplied to the hot stove to increase the usage amount of the converter gas and prevent combustion and emission into the atmosphere. An object of the present invention is to provide a method for supplying gas to a hot stove.

[0008]

A method for supplying fuel gas to a hot stove according to the present invention in accordance with the above object comprises three or more hot stoves for blowing hot air to one blast stove, and The hot blast stove operates by repeating combustion, standby, and blowing in sequence, and when two hot blast stoves partially lap and burn, a coke oven gas, a blast furnace gas, and a converter gas are mixed. In a method of supplying a fuel gas to a hot stove that supplies gas to each hot stove as a fuel gas, one of the two hot stoves that are wrapped and burned, or both of the mixed gas supplied to both hot stoves The mixing amount of the coke oven gas is reduced and the mixing amount of the converter gas is increased while maintaining the calorific value of the fuel gas per unit time at a preset value.

Coke oven gas (CO
G), blast furnace gas (BFG), converter gas (LDG), the calorific value of the coke oven gas is about 4500 kcal /
Nm ^3, blast furnace gas is about 800kcal / Nm ^3, converter gas has become about 1700~2200kcal / Nm ^3. Therefore, when supplying the fuel gas to the hot stove, even if the mixing amount of the coke oven gas is decreased and the mixing amount of the converter gas is increased, the calorific value of the fuel gas per unit time is set to a preset value. Can be maintained.

In the method for supplying fuel gas to a hot stove according to the present invention, there are a plurality of the blast furnaces, each blast furnace includes a hot stove group having three or more hot stoves, and the converter gas is provided. When supplying to the hot blast stove group of each blast furnace through the same blower, the increasing time of the mixing amount of the converter gas to the hot blast stove group of one blast furnace is at least the hot blast of another blast furnace. It is preferable to set the time when one furnace group is burning.

The fuel gas calorific value of the coke oven gas is about 45.
Since it is 00 kcal / Nm ³ which is larger than other gases, the fuel gas is heated to a coke oven gas, a blast furnace gas, and a blast furnace gas under the condition that the fuel gas calorific value per unit time to each hot stove is maintained at a preset value. When the converter gas is mixed and constructed, it is advantageous to mainly determine the mixing ratio of the coke oven gas. As a result, in the state of single-unit combustion, the total amount of heat input to the hot blast stove group is small, so the amount of coke oven gas mixed is small. On the other hand, in the state of two-unit combustion, the total amount of heat input to the hot blast stove increases, so the amount of coke oven gas mixed increases. Therefore, when one hot-blast stove group is in the one-burning state, the other heat-blast stove groups in the two-burning state have a large total amount of heat to be input, and therefore the flow rate of the coke oven gas is large.

Further, the adjustment of the mixing amount of each gas is performed by using a flow meter dedicated to each gas provided in the gas supply equipment, and the measuring range of the flow meter is determined by assuming the maximum mixing amount. Therefore, when measuring a flow rate that is very small with respect to the maximum mixing amount, the measurement accuracy decreases. Therefore, under the condition that the fuel gas calorific value per unit time to the hot blast stove is maintained at a preset value, the converter gas mixing amount in the fuel gas supplied to the hot blast stove that is in the combustion state of one unit is increased. It is not preferable that the coke oven gas mixture amount is decreased by using the coke oven gas mixture amount in the lower limit region where the flowmeter has poor measurement accuracy, and the coke oven gas measurement error increases. On the other hand, since the coke oven gas mixture amount is large in the hot blast stove group that is in the dual combustion state, the fuel gas calorific value per unit time to the hot blast stove group is maintained at a preset value. It is possible to decrease the coke oven gas mixture by increasing the converter gas mixture in the gas,
This is possible while maintaining the accuracy of coke oven gas measurement.

In the method for supplying the fuel gas to the hot stove according to the present invention, the increasing start time T ₁ of the mixing amount of the converter gas
After the preset time t ₃ from the start of the lapped combustion, and the end time T ₂ of the increase of the mixed amount of the converter gas is the average lap combustion time t in the past.
_The time can be calculated by T ₂ = T ₁ + (t ₀ −t ₃ ) based on ₀ .

It is necessary to double the total amount of heat to be input from the furnace replacement time when the combustion of one unit is completed and the combustion of two units is started. Therefore, the gas flow rates of the coke oven gas and the blast furnace gas are instantaneous. However, it takes a certain amount of time for the increased gas flow rates to stabilize. Further, since the converter gas mixture amount is determined based on the converter gas ratio preset with respect to the blast furnace gas mixture amount, it is possible to determine the converter gas mixture amount if the blast furnace gas flow rate changes. Can not. Therefore, t ₃ is set as the time until the flow rates of the coke oven gas and the blast furnace gas stabilize, and until this time elapses, the respective mixing amounts of the coke oven gas and the converter gas are set at the furnace change time. Maintain each mixed amount as specified. On the other hand, from the furnace replacement time when the combustion of two units is completed and the combustion of one unit is started,
It is necessary to reduce the total heat input to 1/2. In the two-unit combustion state, the converter gas mixture amount is increased and the coke oven gas mixture amount is decreased. Therefore, if the mixture amount of each gas is reduced to 1/2 as it is, the coke oven gas mixture amount is measured by the flow meter. It will be controlled in the lower limit region where the weighing accuracy is poor,
It becomes difficult to control the fuel gas calorific value to a preset value. Therefore, at the end time T ₂ of increase in the mixed amount of the converter gas obtained by T ₁ + (t ₀ −t ₃ ), the mixed amount of each of the coke oven gas and the converter gas is set to the initial value when two combustion units are started. Return to each mixing amount.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Next, referring to the attached drawings, an embodiment in which the present invention is embodied will be described to provide an understanding of the present invention. 1 is a block diagram of a fuel gas supply system to which a method for supplying fuel gas to a hot stove according to an embodiment of the present invention is applied, and FIG. 2 shows a method for supplying fuel gas to the hot stove. The partially expanded block diagram of the applied fuel gas supply system, FIG. 3 is an explanatory diagram showing the operating condition of each hot blast stove constituting the hot blast stove group, and FIGS. 4 (A) and 4 (B) are the coke oven gas accompanying the furnace change, 5A, 5B, and 5C are graphs showing the changes over time in the mixing amounts of the converter gas, in which one blast furnace side hot blast stove group (1
A graph showing the time change of the flow rate of each gas in (HS),
2 is a graph showing the time variation of the flow rate of each gas in the blast furnace side hot blast stove group (2HS), 1 blast furnace side hot blast stove group (1HS) and 2
It is a graph which shows the time change of the total pumping amount of the converter gas pressure-fed to the blast furnace side hot-blast stove group (2HS).

As shown in FIGS. 1 and 2, a fuel gas supply system 10 to which a method for supplying a fuel gas to a hot stove according to an embodiment of the present invention is applied is a coke oven gas for supplying a coke oven gas. System 11, blast furnace gas system 12 for supplying blast furnace gas, and converter gas system 13 for supplying converter gas
And the coke oven gas system 11, the blast furnace gas system 12, and the converter gas system 13 are fed under pressure from the coke oven gas, the blast furnace gas, and the converter gas at a predetermined ratio, and are used as fuel gas. It has a gas supply facility 16 for supplying to two hot blast stoves 15 composed of the base hot blast stoves 14. Hereinafter, these will be described in detail.

The coke oven gas system 11 includes a coke oven 17 for producing coke oven gas, and a gas holder for accumulating the coke oven gas produced by the coke oven 17 to absorb variations in the amount of gas produced and variations in the amount of gas used. 18, a dust collector 19 for removing dust in the gas when using the coke oven gas, for example, an electric dust collector, and a blower 20, for example, a blower, for transporting the coke oven gas while maintaining a required pressure. Has been. Similarly, the blast furnace gas system 12 includes a blast furnace 21 that generates blast furnace gas, a gas holder 22 for the blast furnace gas, a dust collector 23, and a blower 24.
In the converter gas system 13, a converter 25 that generates converter gas,
A gas holder 26 for converter gas, a dust collector 27, and a blower 28 are provided, respectively. Further, in the converter gas system 13, a diffusion tower 29 equipped with a torch burner (not shown) that burns and diffuses the converter gas generated in the converter 25 directly into the atmosphere is provided between the converter 25 and the gas holder 26. It is provided via a three-way valve (not shown).

The gas supply equipment 16 includes a gas supply equipment main body 30 for adjusting a fuel gas having a predetermined calorific value by mixing coke oven gas, blast furnace gas and converter gas at a predetermined ratio,
A fuel gas calorimeter 31 for measuring the calorific value of the fuel gas adjusted in the gas supply facility body 30, and a coke oven gas, a blast furnace gas in the gas supply facility body 30 based on the measurement result of the fuel gas calorimeter 31 and And a control device 32 for controlling the mixing ratio of the converter gas. Fuel gas calorimeter 3
A commercially available gas calorimeter can be used for 1. In addition, the gas supply facility body 30 includes a flow meter having an automatic flow rate adjusting function for each of the coke oven gas, the blast furnace gas, and the converter gas for adjusting the fuel gas, and each hot air stove of the adjusted fuel gas. A valve 35 having an automatic opening / closing function, such as a solenoid valve, for controlling the supply to the valve 14 is provided. Control device 32
Includes an electronic computer such as a personal computer,
And a signal for operating each flow meter or valve 35 based on a command from the electronic computer, for example, a sequence controller is provided, and the mixing ratio of each gas is determined based on the measurement result of the fuel gas calorimeter 31. The flow rate of the fuel gas supplied to each hot-blast stove 14 that constitutes each hot-blast stove group 15 is determined.

With such a structure, the blast furnace 2
When there are two hot blast stoves 15 provided with four hot blast stoves 14 for blowing hot air to one, the fuel gas calorific value per unit time was preset for each hot blast stove 15 It can be controlled and supplied so as to have a value. As a result, the temperature fluctuation width of the dome 14a above the hot air stove 14 can be reduced. Further, combustion, standby, and air blowing are sequentially repeated in each hot-blast stove 14, and two hot-blast stoves 14 are simultaneously wrapped and burned in two hot-blast stoves 14 and only one hot-blast stove 14 is used. When one unit combustion is repeated in the hot blast furnace group 15 of one blast furnace 21, when one unit combustion is performed in one blast furnace 21, the hot blast furnace group 15 of the other blast furnace 21, that is, two unit combustion is performed. The mixing amount of the coke oven gas to the two combustion sides is reduced under the condition that the fuel gas calorific value per unit time supplied to the hot-air stove group 15 on the side of the combustion chamber is maintained at a preset value. It may be possible to carry out operations that increase the amount. Further, for example, the control unit 32 sets the furnace replacement time at which the combustion of one unit ends and the combustion of two units starts in each hot-blast stove group 15 and the furnace replacement time at which the combustion of two units ends and the combustion of one unit starts. Each hot stove group 1 in the memory of the computer
It is possible to store a plurality of data by dividing each of them into five. As a result, the average lap combustion time t ₀ can be calculated from these accumulated furnace replacement times, and the time when the two-unit combustion ends can be predicted when the two-unit combustion starts.

As described above, the combustion chamber 36 of each hot blast stove 14
It is possible to heat the heat storage chamber 37 with the heat by supplying the combustion air together with the fuel gas to burn. When the combustion in the combustion chamber 36 is completed, for example, by blowing air preheated to 200 to 250 ° C. to the heat storage chamber 37 from the air pipe 38 to cause heat exchange, hot air at about 1200 ° C. can be obtained, The hot air is passed through the hot air piping 39 to each blast furnace 2
1 can be supplied. The converter gas is the converter 25
Is generated only when the fuel cell is operating, and the converter gas generated at the initial stage of refining has a very low content of CO gas as a combustion source, and thus can be diffused to the atmosphere from the diffusion tower 29,
The CO content gradually increases, and for example, the CO content is 4
When it reaches 0% or more, the three-way valve can be switched to accumulate in the gas holder 26. A part of the converter gas can be directly supplied as fuel gas to the private power plant 33 and the steam generating boiler 34 by the blower 28.

Next, a method of supplying fuel gas to the hot stove according to one embodiment of the present invention will be described in detail. The coke oven gas, the blast furnace gas, and the converter gas supplied by the coke oven gas system 11, the blast furnace gas system 12, and the converter gas system 13 are introduced into the gas supply facility 16. In the gas supply system 16, the amount of heat possessed by the gas (e.g., coke oven gas is about 4500kcal / Nm ^3, blast furnace gas is about 800 kcal / Nm ^3, the converter gas is about 1700-22
Based on 00 kcal / Nm ³ ), the mixing amount of each gas is calculated by an electronic computer in the control device 32 so that the fuel gas calorific value per unit time to each hot blast stove 15 becomes a preset value. Then, the sequence controller outputs each signal for the flow rate adjustment command of each flow meter in the gas supply facility main body 30 according to the calculation result, and the flow meter for each gas adjusts. In addition, the computer in the control device 32 manages the operating conditions of the hot stoves 14 so that the periods of combustion of only one hot stove 14 in each hot stove group 15 do not overlap each other at the same time. Based on this, the sequence controller outputs an opening / closing signal of the valve 35 to supply the fuel gas to only two or one of the four hot blast stoves 14 of each hot blast stove group 15. For example, as shown in FIG. 3, in a hot stove group 15, combustion of hot stoves a and d, hot stove a
Combustion of hot blast stoves a and b, combustion of hot blast stoves b, combustion of hot blast stoves b and c, combustion of hot blast stoves c, and combustion of hot blast stoves c and d. repeat.

When repeating two-unit combustion and one-unit combustion in each hot-blast stove group 15, which hot-blast stove 14 is operated and which hot-blast stove 14 is operated among the four hot-blast stoves 14 included in each hot-blast stove group 15 The control of the order of whether to suspend the operation is performed by the electronic computer of the control device 32. Therefore, each hot stove group 15
For each hot-blast stove 14 constituting the above, the furnace replacement time at which the combustion of one unit is ended and the combustion of two units is started and the furnace replacement time at which the combustion of two units is completed and the combustion of one unit is started are, for example, It can be stored in the storage unit of the electronic computer. Therefore, when the computer calculates the average lap combustion time t _{0 in} which two units are burned from each accumulated furnace replacement time, for example, the hot-blast stove group 15 in the two-unit combustion state becomes the one-unit combustion state. The furnace change time of the hot-blast stove 14 at which the combustion is sometimes stopped can be predicted by adding the average fuel lap baking time t ₀ to the furnace change time at which the hot-blast furnace 14 starts combustion. As a result, when a signal is output from the electronic computer to the sequence controller at the predicted furnace replacement time, each valve 35 opens and closes, and in the four hot blast stoves 14, two combustion and one combustion as shown in FIG. 3 are repeated. You can run.

From the furnace change time when the combustion of one unit is completed and the combustion of two units is started, the total amount of heat to be introduced into the hot stove group 15 becomes 2
The gas flow rates of the coke oven gas and the blast furnace gas instantly increase because it is necessary to double the flow rate. Therefore, it takes a certain amount of time for each gas flow rate to stabilize. Also,
Since the converter gas mixture amount is determined based on the converter gas ratio preset with respect to the blast furnace gas mixture amount, it is impossible to determine the converter gas mixture amount when the blast furnace gas flow rate changes. Therefore, as shown in FIGS. 4 (A) and 4 (B),
Set t ₃ as the unadjustable time until the flow rate of each of the coke oven gas and converter gas stabilizes. Until this time elapses, the flow rate of each of the coke oven gas and the converter gas is reduced to 1 unit. Then, the flow rate is maintained at the set flow rate at the furnace replacement time when the two-unit combustion is started. This t ₃ is determined by reflecting the characteristics of each flow meter used in the gas supply facility body 30, and is, for example, 1 to 2 minutes. When time t ₃ elapses from the time of changing the furnace, the flow rate of each gas stabilizes. Therefore, as shown in FIGS. 4 (A) and 4 (B), per unit time supplied to the hot-air stove group 15 on the two-combustion side. By maintaining the calorific value of the fuel gas at a preset value, the mixing amount of the coke oven gas supplied to the hot-blast stove group 15 on the two-unit combustion side is reduced,
Increase the mixing amount of converter gas. The operation of decreasing the mixing amount of the coke oven gas and increasing the mixing amount of the converter gas was performed for each hot-air stove 14 in which two units were burning, but the gas supply device 16 was used for each hot-air stove 14. If it is provided for each, the operation of decreasing the mixing amount of the coke oven gas and increasing the mixing amount of the converter gas is performed only on one of the hot blast stoves 14 that are burning two. You can

Further, from the furnace change time when the combustion of two units is completed and the combustion of one unit is started, it is necessary to reduce the total amount of heat to be introduced into the hot blast stoves to ½. In the two-unit combustion state, the converter gas mixture amount is increased and the coke oven gas mixture amount is decreased. Therefore, if each gas amount is reduced to 1/2 as it is, the coke oven gas mixture amount is measured by the flowmeter. Therefore, it is difficult to control the fuel gas calorific value to a preset value. Therefore, when the increase start time of the mixed amount of the converter gas is T ₁ , T ₁ + (t ₀
In -t ₃₎ the converter gas mixing amount of increase termination time T _2, which is calculated in a furnace replacement time the mixing amount of each coke oven gas and converter gas by 2 groups combustion finished 1 group combustion is started Return to each mixing amount set in.

Here, the average lap combustion time t ₀ used to predict the furnace replacement time has a fluctuation range of, for example, about 1 to 2 minutes. For this reason, when predicting the furnace replacement time, in consideration of the time of this fluctuation range in advance, the mixing amount of each of the coke oven gas and the converter gas is changed to one in which one combustion is completed and two combustion is started. By returning to the respective mixing amounts set at the replacement time, at the furnace replacement time when the combustion of two units is completed and the combustion of one unit is started, the coke oven gas mixture amount is in the lower limit region where the metering accuracy of the flow meter is poor. You can avoid the situation of controlling. Therefore, as shown by the chain double-dashed lines in FIGS. 4A and 4B, the time corresponding to this fluctuation width is set as t ₄ , and the predicted two-unit combustion ends and one-unit combustion starts. A time t ₄ earlier than the furnace change time is defined as the end time T ₂ of the increase in the mixed amount of the converter gas, and the mixing amount of each of the coke oven gas and the converter gas is completed by starting one combustion and starting two combustions. It is preferable to return to the respective mixing amounts set at the furnace replacement time.

FIGS. 5A and 5B show two units (first blast furnace,
Two hot blast stoves 1 provided for the blast furnace 21 of the second blast furnace)
5 shows the change over time in the mixing amount of each gas constituting the fuel gas with repetition of two-unit combustion and one-unit combustion in FIG. Figure 5
The period indicated by F in (A) is for the first blast furnace side hot blast stove group (1
HS) is the period of one unit combustion, and the period indicated by C, R, and N in FIG. 5B is the second blast furnace side hot blast stove group (2HS).
Is the period of combustion of one unit. The mixing amount of the coke oven gas supplied to the second blast furnace side hot blast stove group (2HS) which is burning two units in the period of the first blast furnace side hot blast stove group (1HS) and G becomes large, and the second blast furnace Side hot stove group (2HS)
The mixing amount of the coke oven gas supplied to the first blast furnace side hot blast stove group (1HS) that is burning two units during the periods of H, L, and N becomes large. Therefore, the amount of coke oven gas mixed is large2
The flow rate of the coke oven gas supplied to the hot-air stove group 15 on the base combustion side is reduced (shown by an arrow ↓) and the flow rate of the converter gas is increased (shown by an arrow ↑). As a result, as shown in FIG. 5 (C), the time change of the total amount of each converter gas pumped in the first blast furnace side hot blast stove group (1HS) and the second blast furnace side hot blast stove group (2HS) Can be approached to.

The embodiment of the present invention has been described above.
The present invention is not limited to this embodiment,
For example, the number of hot blast stoves provided in each hot blast stove group is four, but the number of hot blast stoves is not limited as long as it is three or more. Although the number of blast furnaces is two, the number of blast furnaces is not limited as long as each blast furnace has a hot blast stove group.

[0028]

In the method for supplying a fuel gas to a hot stove according to any one of claims 1 to 3, a unit of a mixed gas to be supplied to either one or both of the two hot stoves that are wrapped and burned. While maintaining the calorific value of the fuel gas per hour at a preset value, the mixing amount of the coke oven gas is decreased and the mixing amount of the converter gas is increased, so that the average pumping amount of the converter gas is increased. As a result, it is possible to prevent pressure loss and prevent the amount of converter gas generated from becoming excessive with respect to the amount used. As a result, it is possible to prevent the converter gas from being burnt and diffused into the atmosphere from the stripping tower as excess gas, and it is possible to effectively use the thermal energy.

Particularly, in the method for supplying the fuel gas to the hot stove according to the second aspect, there are a plurality of blast furnaces, and each blast furnace has three blast furnaces.
It is equipped with a hot blast stove having more than one hot blast stove, and when the converter gas is supplied to the hot blast stove group of each blast furnace via the same blower, When the mixing amount increases, at least one of the hot blast stoves of other blast furnaces
Since it is the time when the base combustion is performed, by increasing the usage amount of the converter gas in the hot blast stove group on the two-unit combustion side when the usage amount of the converter gas decreases at the 1-unit combustion time. It is possible to prevent the amount of converter gas generated from becoming excessive with respect to the amount used. Further, in the hot blast stove group on the two-combustion side that reduces the usage amount of the coke oven gas, it is the time when the usage amount of the coke oven gas to be supplied increases because the total heat input to the hot blast furnace group increases. Therefore, even if the amount of coke oven gas used is reduced, the flow meter that measures the coke oven gas mixture amount will not be used in the lower limit region where the measurement accuracy is poor, and the coke oven gas measurement accuracy can be maintained. It will be possible.

In the method for supplying the fuel gas to the hot stove according to the third aspect, the increase start time T ₁ of the mixing amount of the converter gas is increased.
After the preset time t ₃ from the start of the lapped combustion and the end time T ₂ of the increase in the mixing amount of the converter gas T ₂ based on the average lap combustion time t ₀ in the past. = because the time calculated at _{T 1 + (t 0 -t 3} ) , at _{T 1 + (t 0 -t 3} ) increasing end time T ₂ of the converter gas mixing amount determined by, coke oven gas and converter If the respective mixing amounts of the gases are returned to the respective mixing amounts set at the beginning of the combustion of the two units, the coke oven gas mixing amount will not be controlled in the lower limit region where the metering accuracy of the flow meter is poor. .

[Brief description of drawings]

FIG. 1 is a configuration diagram of a fuel gas supply system to which a method for supplying fuel gas to a hot stove according to an embodiment of the present invention is applied.

FIG. 2 is a partially enlarged configuration diagram of a fuel gas supply system to which the method for supplying fuel gas to the hot stove is applied.

FIG. 3 is an explanatory diagram showing an operating condition of each hot stove that constitutes the hot stove group.

4 (A) and 4 (B) are graphs showing changes over time in the mixing amounts of coke oven gas and converter gas, respectively, due to furnace replacement.

5 (A), (B), and (C) show changes over time in the flow rate of each gas in the first blast furnace side hot blast stove group (1HS) to which the method of supplying fuel gas to the same hot blast stove is applied. Graph, graph showing the time change of the flow rate of each gas in the second blast furnace side hot blast furnace group (2HS), the first blast furnace side hot blast furnace group (1H
5 is a graph showing a temporal change in the total pumping amount of the converter gas to be pumped to (S) and the second blast furnace side hot blast stove group (2HS).

FIG. 6 is a block diagram of an integrated steel mill having a blast furnace.

FIG. 7 is a partially enlarged configuration diagram of a fuel gas supply system to which a method for supplying fuel gas to a hot stove according to a conventional example is applied.

8 (A), (B), (C), (D), and (E) are temporal changes in the total amount of heat supplied to the hot blast stoves in the method for supplying fuel gas to the hot blast stoves according to the conventional example. , A graph showing the set value of the combustion gas calorific value and its control result, a graph showing the time change of the blast furnace gas flow rate, a graph showing the time change of each flow rate of the coke oven gas and the converter gas, the converter gas ratio It is a graph which shows the time change of.

9 (A), (B), and (C) are temporal changes of respective gas flow rates in a first blast furnace side hot blast stove group (1HS) to which a fuel gas supply method according to a conventional example is applied. Showing a graph, a graph showing a time change of each gas flow rate in the second blast furnace side hot blast stove group (2HS), a pressure transfer to the first blast furnace side hot blast stove group (1HS) and the second blast furnace side hot blast stove group (2HS) It is a graph which shows the time change of the total pumping quantity of furnace gas.

[Explanation of symbols]

10: Fuel gas supply system, 11: Coke oven gas system, 12: Blast furnace gas system, 13: Converter gas system, 14:
Hot blast stove, 14a: dome, 15: hot blast stove group, 16: gas supply equipment, 17: coke oven, 18: gas holder, 1
9: Dust collector, 20: Blower, 21: Blast furnace, 22: Gas holder, 23: Dust collector, 24: Blower, 25: Converter, 26: Gas holder, 27: Dust collector, 28: Blower, 29 : Dispersion tower, 30: Gas supply equipment main body, 31: Fuel gas calorimeter, 32: Control device, 33: Private power plant, 3
4: Steam generating boiler, 35: Valve, 36: Combustion chamber, 37:
Heat storage chamber, 38: Air piping, 39: Hot air piping

Claims (3)

[Claims] 1. A blast furnace comprising three or more hot blast furnaces for blowing hot air to each blast furnace, wherein each hot blast furnace operates by repeating combustion, standby, and blast in sequence, and moreover, two hot blast furnaces are provided. When the base partially laps and performs combustion, coke oven gas, blast furnace gas, in the method of supplying fuel gas to the hot blast stoves that supply mixed gas as a fuel gas to the hot blast stoves, While maintaining the fuel gas calorific value per unit time of the mixed gas supplied to either one or both of the two hot air stoves burning in the lap and burning the coke oven gas, A method for supplying a fuel gas to a hot stove, which comprises decreasing the mixing amount and increasing the mixing amount of the converter gas. 2. The method for supplying fuel gas to a hot stove according to claim 1, wherein there are a plurality of blast furnaces, and each blast furnace has three blast furnaces.
A hot blast stove having the hot blast stove of more than one base, while supplying the converter gas to the hot blast stove of each of the blast furnaces via the same blower, the hot blast stove of one of the blast furnaces A method for supplying fuel gas to a hot blast stove, characterized in that the time of increasing the mixing amount of the converter gas is a time when at least one hot blast stove group of another blast furnace is burning. 3. The method of supplying a fuel gas to a hot stove according to claim 1 or 2, wherein an increase start time T ₁ of the mixing amount of the converter gas is preset after the wrapping and the start of combustion. and after the time t _3, further increasing end time T ₂ of the mixing amount of the converter gas, at an average lap combustion time t ₀ based on _{T 2 = T 1 + (t} 0 -t 3) in the past A method of supplying fuel gas to a hot stove, characterized in that the calculated time is set.