Operation control method of hot-blast stove, hot-blast stove, and program for controlling operation of hot-blast stove

Abstract

To provide an operation control method or the like of a hot-blast stove capable of making the concentration of nitrogen oxide in combustion exhaust gas discharged from the hot-blast stove appropriate even when combustion air having a higher oxygen concentration than air is used.SOLUTION: In an operation control method of a hot blast stove, hot blast is generated by burning mixed gas comprising fuel gas containing blast furnace gas discharged from a blast furnace and coke oven gas discharged from a coke oven, and combustion air having oxygen concentration higher than that of air. The operation control method of the hot-blast stove includes a mixing ratio setting step of setting a mixing ratio of the blast furnace gas and the coke oven gas of the fuel gas according to a temperature range of a flame of the mixed gas, and a combustion step of combusting the mixed gas of the set mixing ratio.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an operation control method for a hot blast stove that generates hot air by burning a fuel gas including blast furnace gas and coke oven gas and combustion air having a higher oxygen concentration than air in a burner, a hot blast stove, and a program for controlling the operation of the hot blast stove.

Background Art

[0002] In a blast furnace, molten iron is produced by smelting and reducing iron ore. When smelting and reducing are performed, hot air is blown into the furnace from tuyeres provided in the blast furnace. The hot air blown into the blast furnace is generated by a regenerative heat exchanger called a hot blast stove.

[0003] Three to four hot blast stoves are installed for one blast furnace. For example, while one hot blast stove is supplying hot air, the other hot blast stoves are stopped, and after a predetermined time has elapsed, the operating hot blast stove is stopped, and the other stopped hot blast stoves are restarted. In this way, the hot blast stoves sequentially alternate between the operating state and the stopped state while continuously supplying hot air to the blast furnace.

[0004] In a hot blast stove, an operation is performed by alternately switching between a combustion step of burning gas in a combustion chamber and a blowing step of storing heat generated by combustion in a heat storage body and blowing air to the heat storage body.

[0005] In the combustion step of the hot blast stove, a gas obtained by mixing blast furnace gas (BFG: Blast Furnace Gas) and coke oven gas (COG: Coke Oven Gas) is used as a fuel gas. The blast furnace gas (BFG) and the coke oven gas (COG) have different calorific values by combustion. Therefore, the combustion gas is adjusted to perform proper combustion with an appropriate mixing ratio of the blast furnace gas (BFG) and the coke oven gas (COG).

[0006] In addition, combustion air is used to burn fuel gas. As the combustion air, oxygen-enriched air with a higher oxygen concentration than that of the air is used by adding oxygen to the air. Thereby, oxygen-enriched combustion is achieved, and stable operation and energy saving of the hot blast stove are achieved.

[0007] As an operation method of the hot blast stove, in order to improve the heat quantity per unit, the flow rate of gas in the combustion process is controlled. For example, Patent Document 1 discloses that by controlling the supply flow rates of fuel gas and combustion air, the mixing ratio of coke oven gas to blast furnace gas is set in the range of 2.3 to 3.0%, and the exhaust gas oxygen concentration of the hot blast stove is set to 0.4 to 0.6%.

[0008] In addition, deterioration of the hot blast stove is also prevented by maintaining the upper surface temperature of the regenerative bricks forming the combustion chamber within an appropriate range. For example, Patent Document 2 discloses that in a combustion furnace using a ceramic burner, oxygen in the combustion air is enriched according to the capacity of the combustion chamber and the distance to the upper surface of the regenerative checker brick to adjust the flame length.

[0009] Furthermore, the life of the hot blast stove is extended by suppressing fluctuations in the thermal expansion rate of the hot blast stove. For example, Patent Document 3 discloses that one of the gas ratio (BFG / COG) of fuel gas and the oxygen concentration of combustion air is changed according to a change in the other.

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0011] Incidentally, the emission concentration and emission amount of nitrogen oxides discharged from the hot blast stove are subject to legal regulations. However, in the technology described in Patent Document 1, nitrogen oxides (NOx) in the combustion exhaust gas discharged from the hot blast stove are not considered. Therefore, the method described in Patent Document 1 may not comply with the legal regulations on nitrogen oxides.

[0012] In the technology described in Patent Document 2, oxygen enrichment of combustion air is performed. When the oxygen-enriched combustion air is used in the combustion process, the temperature of the flame in the combustion process rises, so the nitrogen oxides contained in the combustion exhaust gas increase. However, in the technology described in Patent Document 2, nitrogen oxides (NOx) in the combustion exhaust gas discharged from the hot blast stove are not considered. Therefore, the method described in Patent Document 2 may not comply with the legal regulations on nitrogen oxides.

[0013] Similarly, in the technology described in Patent Document 3, nitrogen oxides (NOx) in the combustion exhaust gas discharged from the hot blast stove are not considered. Therefore, the method described in Patent Document 3 may not comply with the legal regulations on nitrogen oxides.

[0014] The present invention has been made in view of the above problems, and an object thereof is to provide an operation control method of a hot blast stove and the like that can make the concentration of nitrogen oxides in the combustion exhaust gas discharged from the hot blast stove appropriate even when combustion air having a higher oxygen concentration than air is used.

Means for Solving the Problems

[0015] To solve the above problems, the present invention has the following features.

[0016] [1] An operation control method for a hot blast stove that burns a mixed gas including fuel gas containing blast furnace gas discharged from a blast furnace and coke oven gas discharged from a coke oven, and combustion air having an oxygen concentration higher than that of air to generate hot air, comprising: a mixing ratio setting step of setting a mixing ratio of the blast furnace gas and the coke oven gas in the fuel gas according to a temperature range of a flame of the mixed gas; a combustion step of burning the mixed gas having the set mixing ratio, the operation control method for a hot blast stove. [2] a flame temperature calculation step of calculating an adiabatic flame temperature, which is a temperature of combustion gas generated by combustion of the mixed gas; a mixing ratio calculation step of calculating the mixing ratio using the adiabatic flame temperature and the temperature range of the flame, the operation control method for a hot blast stove according to [1]. [3] The operation control method for a hot blast stove according to [1] or [2], including a flow rate setting step of setting a flow rate of the fuel gas in the mixed gas according to a heat quantity range generated by combustion of the fuel gas. [4] having a heat quantity calculation step of calculating a theoretical combustion heat quantity of the fuel gas, wherein the flow rate setting step sets the flow rate of the fuel gas using the theoretical combustion heat quantity calculated in the heat quantity calculation step as the heat quantity range, the operation control method for a hot blast stove according to [3]. [5] In the flow rate setting step, the flow rate of the fuel gas in the mixed gas is set according to a temperature range of combustion exhaust gas after the combustion gas of the mixed gas contacts a heat storage body, the operation control method for a hot blast stove according to [3] or [4]. [6] In the mixing ratio setting step, the mixing ratio according to the oxygen concentration of the combustion air is set, the operation control method for a hot blast stove according to any one of [1] to [5]. [7] In the mixing ratio setting step, the mixing ratio according to at least one of the flow rates of the blast furnace gas and the coke oven gas is set, The operation control method of the hot blast stove according to any one of [1] to [6]. [8] A fuel gas supply system that supplies fuel gas including blast furnace gas discharged from a blast furnace and coke oven gas discharged from a coke oven to a combustion chamber, a combustion air supply system that supplies combustion air having an oxygen concentration higher than that of air to the combustion chamber, a burner that burns a mixed gas including the fuel gas and the combustion air in the combustion chamber, a heat storage body that accumulates sensible heat of combustion exhaust gas generated by combustion of the mixed gas, and a wind supply system that supplies wind to the heat storage body. A hot blast stove comprising: A hot blast stove including a mixing ratio setting unit that sets a mixing ratio of the blast furnace gas and the coke oven gas in the fuel gas according to a temperature range of a flame of the mixed gas. [9] Including a flame temperature calculation unit that calculates an adiabatic flame temperature, which is the temperature of combustion gas generated by combustion of the mixed gas. The hot blast stove according to [8], wherein the mixing ratio setting unit sets the mixing ratio using the adiabatic flame temperature and the temperature range of the flame.

[10] The hot blast stove according to [8] or [9], including a flow rate setting unit that sets a flow rate of the fuel gas in the mixed gas according to a heat quantity range generated by combustion of the mixed gas.

[11] Having a heat quantity calculation unit that calculates a theoretical combustion heat quantity of the fuel gas. The hot blast stove according to any one of [8] to

[10] , wherein the flow rate setting unit sets the flow rate of the fuel gas using the theoretical combustion heat quantity calculated by the heat quantity calculation unit as the heat quantity range.

[12] An operation control program for a hot blast stove configured to execute each step of the operation control method of the hot blast stove according to [1] to [7] by a computer.

Effect of the Invention

[0017] According to the operation control method of the hot blast stove of the present invention, etc., according to the temperature range of the flame of the mixed gas including fuel gas and combustion air with an oxygen concentration higher than that of air, the mixing ratio of the blast furnace gas and the coke oven gas of the fuel gas is set, and the mixed gas is burned. Therefore, the flame temperature can be maintained in an appropriate state. As a result, even when oxygen-enriched air with a higher oxygen concentration than air is used as the combustion air of the hot blast stove, the concentration of nitrogen oxides in the combustion exhaust gas discharged from the hot blast stove can be made appropriate.

Brief Description of Drawings

[0018]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0019] (First Embodiment) Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration diagram of a hot blast stove. As shown in FIG. 1, the hot blast stove 100 includes a combustion chamber 10 for burning combustible gas, a heat storage chamber 20 for storing the combustion heat generated in the combustion chamber 10, and a connection passage 30 for connecting the combustion chamber 10 and the heat storage chamber 20. In the present embodiment, the hot blast stove 100 is an external combustion type (Coppers type) in which the combustion chamber 10 and the heat storage chamber 20 are separated.

[0020] Below the combustion chamber 10, a burner 11 for burning combustible gas is provided. In the present embodiment, as the combustible gas, a fuel gas and a mixed gas containing combustion air are used. The burner 11 has a fuel gas injection nozzle 11a for supplying fuel gas to the combustion chamber 10 and a combustion air injection nozzle 11b for supplying combustion air to the combustion chamber 10. The fuel gas injection nozzle 11a and the combustion air injection nozzle 11b are provided to open on the inner surface of the combustion chamber 10.

[0021] A fuel gas supply system 40, which is a pipe for transporting fuel gas, is connected to the fuel gas injection nozzle 11a. In other words, the fuel gas supply system 40 supplies fuel gas to the combustion chamber 10 via the fuel gas injection nozzle 11a.

[0022] The fuel gas supply system 40 has a blast furnace gas supply system 41 for supplying blast furnace gas (BFG: Blast Furnace Gas) discharged from a blast furnace and a coke oven gas supply system 42 for supplying coke oven gas (COG: Coke Oven Gas) discharged from a coke oven.

[0023] Blast furnace gas is a by-product gas discharged when pig iron is produced by reducing iron ore in a blast furnace. A typical composition of blast furnace gas is, for example, 21 - 30% by volume of carbon monoxide, which is a combustible component, 50 - 60% by volume of nitrogen, which is a non-combustible component, and 10 - 22% by volume of carbon dioxide.

[0024] The ignition point of blast furnace gas having such a composition is 630 - 650°C. The combustion range of blast furnace gas mixed with air is 27 - 75% by volume. The lower calorific value of blast furnace gas is, for example, 3.45 MJ / Nm 3 or so.

[0025] Coke oven gas is a by-product gas discharged when coke is produced by high-temperature carbonization of coal in a coke oven. A typical composition of coke oven gas is 46 - 60 vol% hydrogen, 20 - 35 vol% methane, 5 - 10 vol% carbon monoxide, and 2 - 4 vol% hydrocarbons such as ethylene. Also, coke oven gas contains impurities containing nitrogen atoms such as ammonia (NH 3 ). The lower calorific value of coke oven gas is, for example, about 18.0 MJ / Nm 3 .

[0026] The blast furnace gas supply system 41 is provided with a blast furnace gas flow control valve 43 for adjusting the flow rate of blast furnace gas. The coke oven gas supply system 42 is provided with a coke oven gas flow control valve 44 for adjusting the flow rate of coke oven gas.

[0027] The downstream side of the coke oven gas flow control valve 44 in the coke oven gas supply system 42 is connected to the downstream side of the blast furnace gas flow control valve 43. At the connection part, blast furnace gas and coke oven gas are mixed and supplied as fuel gas containing these to the fuel gas injection nozzle 11a of the burner 11.

[0028] By adjusting the valve opening degrees of the blast furnace gas flow control valve 43 and the coke oven gas flow control valve 44, the flow rate of the fuel gas supplied to the combustion chamber 10 and the mixing ratio of blast furnace gas and coke oven gas are adjusted. Incidentally, preheated blast furnace gas and coke oven gas supplied from the blast furnace gas supply system 41 and the coke oven gas supply system 42 may be used.

[0029] The combustion air injection nozzle 11b is connected to a combustion air supply system 50 which is a pipe for transporting combustion air. In other words, the combustion air supply system 50 supplies combustion air to the combustion chamber 10 through the combustion air injection nozzle 11b.

[0030] The combustion air supply system 50 supplies combustion air to the combustion chamber 10. The combustion air supply system 50 includes an air supply system 51 that supplies air collected from the atmosphere and an oxygen supply system 52 that supplies oxygen generated from an oxygen generator (not shown).

[0031] The air supply system 51 is provided with an air volume adjustment valve 53 for adjusting the flow rate of air. The oxygen supply system 52 is provided with an oxygen flow rate adjustment valve 54. The downstream side of the oxygen flow rate adjustment valve 54 of the oxygen supply system 52 is connected to the downstream side of the air volume adjustment valve 53. At this connection part, air and oxygen are mixed and supplied as combustion air containing these to the combustion air blowing nozzle 11b of the burner 11. That is, the combustion air is a gas having a higher oxygen concentration than air.

[0032] By adjusting the valve opening degrees of the air volume adjustment valve 53 and the oxygen flow rate adjustment valve 54, the flow rate of the combustion air supplied to the burner 11 and the oxygen concentration contained in the combustion air can be adjusted. Incidentally, the air and oxygen supplied from the air supply system 51 and the oxygen supply system 52 may be preheated as necessary.

[0033] The combustion chamber 10 is provided with a hot air supply system 12 that supplies hot air to a blast furnace (not shown). The hot air supply system 12 is provided with a hot air valve 13 for adjusting the flow rate of the hot air in the hot air supply system 12. The flow rate of the hot air supplied to the blast furnace is adjusted by the opening degree of the hot air valve 13.

[0034] The regenerator 20 has a regenerator body 21. The regenerator body 21 is not particularly limited, and for example, refractory bricks or the like made of refractory materials can be used.

[0035] The combustion gas generated by combustion in the combustion chamber 10 exchanges heat with the regenerator body 21 to become combustion exhaust gas. An exhaust system 60 for discharging the combustion exhaust gas is provided at the lower part of the regenerator 20. The exhaust system 60 is provided with an exhaust valve 61. The combustion exhaust gas is exhausted to the outside according to the opening degree of the exhaust valve 61.

[0036] The exhaust system 60 may be provided with an exhaust gas thermometer 62 for measuring the temperature of the combustion exhaust gas. The temperature of the combustion exhaust gas measured by the exhaust gas thermometer 62 may be used, for example, to estimate the combustion state in the hot blast stove 100.

[0037] Also, a wind supply system 63 for supplying normal temperature air to the regenerator 20 is connected to the lower part of the regenerator 20. The wind supply system 63 is provided with a cold air flow control valve 64. The cold air flow control valve 64 is opened, for example, when the combustion of the mixed gas in the combustion chamber 10 ends. The flow rate of the normal temperature air supplied to the regenerator 20 is adjusted by the opening degree of the cold air flow control valve 64.

[0038] The hot blast stove 100 has a control unit 70 for controlling its operation. The control unit 70 is electrically connected to the hot blast valve 13, the blast furnace gas flow control valve 43, the coke oven gas flow control valve 44, the air volume control valve 53, the oxygen flow control valve 54, the exhaust valve 61, and the cold air flow control valve 64. The control unit 70 can independently adjust the opening degrees of the hot blast valve 13, the blast furnace gas flow control valve 43, the coke oven gas flow control valve 44, the air volume control valve 53, the oxygen flow control valve 54, the exhaust valve 61, and the cold air flow control valve 64.

[0039] The control unit 70 opens the blast furnace gas flow control valve 43, the coke oven gas flow control valve 44, the air volume control valve 53, and the oxygen flow control valve 54 to burn the mixed gas with the burner 11.

[0040] Specifically, the control unit 70 adjusts the opening degrees of the blast furnace gas flow control valve 43 and the coke oven gas flow control valve 44 to inject the fuel gas from the fuel gas injection nozzle 11a into the combustion chamber 10. The control unit 70 adjusts the opening degrees of the air volume control valve 53 and the oxygen flow control valve 54 to inject the combustion air from the combustion air injection nozzle 11b into the combustion chamber 10.

[0041] In the combustion chamber 10, fuel gas and combustion air are mixed to form a mixed gas. Note that the combustion chamber 10 is maintained at, for example, 600 °C or higher, which is the ignition temperature of the mixed gas. Therefore, when the mixed gas is supplied to the combustion chamber 10, the mixed gas burns.

[0042] The combustion gas generated by the combustion of the mixed gas rises in the combustion chamber 10 and, when it reaches the upper part of the combustion chamber 10, flows into the regenerator 20 through the connecting passage 30. The upper part of the regenerator 20 is sealed, and the combustion gas that has flowed into the regenerator 20 flows downward in the regenerator 20.

[0043] As the combustion gas passes through the regenerator 21 disposed in the regenerator 20, sensible heat possessed by the combustion gas is stored in the regenerator 21 by heat exchange. The combustion gas that has passed through the regenerator 21 becomes combustion exhaust gas from which thermal energy has been released. The combustion exhaust gas is exhausted to the outside of the hot blast stove 100 through the exhaust system 60.

[0044] When the combustion gas is supplied to the regenerator 21 for a certain period of time, the control unit 70 closes the blast furnace gas flow rate adjustment valve 43, the coke oven gas flow rate adjustment valve 44, the air volume adjustment valve 53, and the oxygen flow rate adjustment valve 54 to stop the combustion in the combustion chamber 10. Next, the control unit 70 closes the exhaust valve 61 and opens the hot blast valve 13 and the cold air flow rate adjustment valve 64. Thereby, normal temperature air (cold air) in the air supply system 63 is supplied to the regenerator 20.

[0045] When the normal temperature air supplied to the regenerator 20 moves from the lower part to the upper part of the regenerator 20, heat exchange is performed with the regenerator 21 and its temperature rises. The temperature of the hot air whose temperature has risen by the heat exchange reaches, for example, 900 to 1300 °C. The hot air flows into the blast furnace as hot blast in the order of the connecting passage 30, the combustion chamber 10, and the hot blast supply system 12.

[0046] When hot air is supplied to the blast furnace for a certain period of time, the control unit 70 opens the exhaust valve 61 and closes the hot air valve 13 and the cold air flow control valve 64. Next, the control unit 70 opens the blast furnace gas flow control valve 43, the coke oven gas flow control valve 44, the air volume control valve 53, and the oxygen flow control valve 54 to resume combustion in the combustion chamber 10.

[0047] In this way, the combustion of the mixed gas in the combustion chamber 10 and the blowing of hot air to the blast furnace are performed alternately. For example, it is preferable that 3 to 4 hot blast stoves 100 are installed for one blast furnace. By providing a plurality of hot blast stoves 100 in this way, it becomes possible to always blow hot air from any one of the hot blast stoves 100 to the blast furnace.

[0048] FIG. 2 is a block diagram showing the configuration of the control unit 70. As shown in FIG. 2, the control unit 70 is connected to an input unit 77, an output unit 78, and a storage unit 79 via a bus B.

[0049] The control unit 70 is a general-purpose computer such as a workstation or a personal computer. The control unit 70 includes a mixing ratio setting unit 71, a flow rate setting unit 72, a flame temperature calculation unit 73, a mixing ratio calculation unit 74, a heat quantity calculation unit 75, and a flow rate calculation unit 76. The mixing ratio setting unit 71, the flow rate setting unit 72, the flame temperature calculation unit 73, the mixing ratio calculation unit 74, the heat quantity calculation unit 75, and the flow rate calculation unit 76 function by executing various programs stored in the storage unit 79. That is, a program for operating control of the hot blast stove is stored in the storage unit 79.

[0050] The mixing ratio setting unit 71 sets the mixing ratio of the blast furnace gas and the coke oven gas of the fuel gas so that the flame temperature due to the combustion of the mixed gas falls within a predetermined temperature range. The mixing ratio of the blast furnace gas and the coke oven gas (hereinafter, also simply referred to as the mixing ratio) can be represented by, for example, the volume ratio of the blast furnace gas and the coke oven gas of the fuel gas.

[0051] The mixing ratio setting unit 71 gives an opening command to the blast furnace gas flow control valve 43 to adjust the flow rate of the blast furnace gas supplied from the blast furnace gas supply system 41. It gives an opening command to the coke oven gas flow control valve 44 to adjust the flow rate of the coke oven gas supplied from the coke oven gas supply system 42.

[0052] The flow rate setting unit 72 controls the flow rate of the fuel gas supplied to the burner 11 while maintaining the mixing ratio set by the mixing ratio setting unit 71 so that the amount of heat generated by the combustion of the fuel gas becomes a predetermined amount. The flow rate setting unit 72 gives an opening command to the air flow control valve 53 to control the flow rate of the air supplied from the air supply system 51. Further, the flow rate setting unit 72 gives an opening command to the oxygen flow control valve 54 to control the flow rate of the oxygen supplied from the oxygen supply system 52. That is, the flow rate setting unit 72 can adjust the flow rate of the combustion air supplied to the burner 11 and the oxygen concentration contained in the combustion air.

[0053] Thereby, while controlling so that the concentration of nitrogen oxides contained in the combustion exhaust gas does not become excessive using the mixing ratio setting unit 71, the amount of heat generated in the combustion chamber 10 can be ensured, and sufficient thermal energy can be imparted to the hot blast supplied to the blast furnace.

[0054] The flame temperature calculation unit 73 calculates the adiabatic flame temperature as the flame temperature. The adiabatic flame temperature refers to the temperature of the combustion gas after combustion when it is assumed that the combustion proceeds adiabatically. Incidentally, the flame temperature is, for example, 1400 to 1600 °C.

[0055] Since the flame temperature calculation unit 73 is provided, even when it is difficult to directly measure the flame temperature due to the combustion of the mixed gas, the flame temperature due to the combustion of the mixed gas can be estimated.

[0056] The flame temperature calculation unit 73 may be a program capable of executing the above calculation. Also, it may be configured to give input data to a calculation tool using a generally publicly available calculation tool for adiabatic flame temperature described later and obtain the calculation result of the adiabatic flame temperature.

[0057] The mixing ratio calculation unit 74 calculates the mixing ratio so that the flame temperature calculated by the flame temperature calculation unit 73 falls within a predetermined temperature range.

[0058] The calorific value calculation unit 75 calculates the theoretical calorific value of combustion, which is the calorific value generated when the fuel gas burns completely, as the calorific value. The theoretical calorific value of combustion is calculated using the lower calorific value, which is the calorific value excluding the latent heat of vaporization of the water vapor generated during the combustion of the fuel gas. The lower calorific value varies depending on the mixing ratio of the blast furnace gas and the coke oven gas contained in the fuel gas per unit volume. The theoretical calorific value of combustion is calculated by multiplying the lower calorific value of the fuel gas by the flow rate of the fuel gas.

[0059] The flow rate calculation unit 76 calculates the flow rate of the fuel gas so that the theoretical calorific value of combustion calculated by the calorific value calculation unit 75 falls within a predetermined range (calorific value range). The flow rate calculation unit 76 calculates the flow rate per unit time of the fuel gas supplied from the fuel gas supply system 40 so that the calculated theoretical calorific value of combustion falls within a predetermined range.

[0060] The input unit 77 is an input device configured to be able to input data to the control unit 70. As the input unit 77, for example, a keyboard, a touch panel provided integrally with a display, or the like can be used.

[0061] The output unit 78 is an output device that outputs the data generated by the control unit 70. As the output unit 78, for example, a display device such as a liquid crystal display can be used.

[0062] The storage unit 79 is an information recording medium such as a rewritable flash memory, a hard disk, or a memory card, for example. The storage unit 79 stores, for example, programs for executing the respective functions of the control unit 70 and data.

[0063] Figure 3 shows the processing flow of the operation control method of the hot blast stove 100. The operation control of the hot blast stove 100 is started, for example, when the input unit 77 receives an input from an operator and the input data is input to the control unit 70.

[0064] As shown in FIG. 3, the flame temperature calculation unit 73 calculates the flame temperature and executes a flame temperature calculation step (step S11).

[0065] The adiabatic flame temperature can be calculated, for example, from a calculation based on the calorific value and the heat capacity of the combustion products. In this calculation, assuming that the combustion reaction of the mixed gas is completed and chemical equilibrium and thermal equilibrium are established, the types and concentrations of the combustion products may be calculated from the equilibrium calculation. Further, the flame temperature calculation unit 73 may calculate the adiabatic flame temperature obtained assuming no heat loss to the outside as the flame temperature.

[0066] Assuming that combustion is carried out adiabatically, all the heat of combustion generated by combustion is used for the temperature rise of the fuel gas, and each component composition in the fuel gas dissociates as the temperature rises.

[0067] The adiabatic flame temperature means the temperature that is predicted to be reached when the heat of combustion is used for the temperature rise of the fuel gas in consideration of the dissociation of each component composition of such fuel gas.

[0068] The adiabatic flame temperature can be calculated using, as inputs, the content rate for each gas component contained in the fuel gas, the content rate for each gas component contained in the combustion air, and the supply ratio of the fuel gas and the combustion air. Since the adiabatic flame temperature is affected by the gas components contained in the fuel gas, it changes depending on the mixing ratio of the blast furnace gas and the coke oven gas that make up the fuel gas.

[0069] Further, since the adiabatic flame temperature is affected by the gas components contained in the combustion air, it changes depending on the oxygen concentration of the oxygen-enriched air in which oxygen is enriched. The adiabatic flame temperature can be calculated, for example, by the method described in a non-patent document (Research Report No. 8 of Tokyo Metropolitan College of Technology, March 1980, p. 71).

[0070] The adiabatic flame temperature calculation unit 73 calculates the adiabatic flame temperature using the content rate of each gas component of the fuel gas, the content rate of each gas component of the combustion air, and the supply ratio of the fuel gas and the combustion air.

[0071] Also, it is advisable to perform calculations in advance with various changes to the adiabatic flame temperature Tf and the like using a calculation tool for the adiabatic flame temperature, and create a regression equation shown in Equation (1) in advance.

[0072] Tf = f(Br, Oc, Mr) (1) Tf: Adiabatic flame temperature (K) Br: Volume content rate of coke oven gas contained in the fuel gas (-) Oc: Oxygen content rate of the combustion air (-) Mr: Flow rate ratio of the combustion air to the theoretical combustion air required to completely burn the fuel gas (air ratio) (-)

[0073] Here, f represents a function, and a linear regression equation or a non - linear regression equation that outputs the value of the variable Tf by inputting the values of the variables Br, Oc, and Mr can be used. However, the function f is not limited to a regression equation, and it may be configured by a learned model learned by a method such as a neural network that inputs the variables Br, Oc, and Mr and outputs the variable Tf.

[0074] Here, when operating the hot blast stove 100 with a mixed gas containing the fuel gas and combustion air with an oxygen concentration equivalent to the oxygen concentration of the air, it is called normal operation. Also, when operating the hot blast stove 100 with a mixed gas containing the fuel gas and combustion air with an oxygen concentration higher than the oxygen concentration of the air, it is called oxygen - enriched operation.

[0075] The flame temperature calculation unit 73 reads and acquires the normal operating conditions and oxygen enrichment operating conditions of the hot blast stove 100 from the storage unit 79. Specifically, the flame temperature calculation unit 73 acquires at least one of the set values and actual values of the flow rates of the blast furnace gas and coke oven gas supplied to the burner 11 during normal operation and oxygen enrichment operation. The flame temperature calculation unit 73 acquires at least one of the set values and actual values of the flow rates of air and oxygen supplied to the burner 11 during normal operation and oxygen enrichment operation.

[0076] The flame temperature calculation unit 73 calculates the adiabatic flame temperature Tf during normal operation and oxygen enrichment operation using these acquired set values or actual values. The flame temperature calculation unit 73 may acquire these set values or actual values every time a predetermined time elapses and calculate the adiabatic flame temperature Tf during normal operation and oxygen enrichment operation.

[0077] In addition, when calculating the adiabatic flame temperature Tf in the case of first performing the oxygen enrichment operation, the flame temperature calculation unit 73 calculates the adiabatic flame temperature Tf in the case of performing the oxygen enrichment operation at the mixing ratio corresponding to the adiabatic flame temperature Tf in normal operation. The flame temperature calculation unit 73 stores these calculated adiabatic flame temperatures Tf in the storage unit 79.

[0078] Next, the mixing ratio calculation unit 74 calculates the mixing ratio so that the flame temperature calculated in the flame temperature calculation step of step S11 falls within a predetermined temperature range, and executes the mixing ratio calculation step (step S12).

[0079] In the mixing ratio calculation step of step S12, the mixing ratio calculation unit 74 acquires the adiabatic flame temperature Tf in the case of performing the oxygen enrichment operation at the mixing ratio corresponding to the adiabatic flame temperature Tf in normal operation. The mixing ratio calculation unit 74 determines whether or not the adiabatic flame temperature Tf is within a predetermined temperature range.

[0080] The predetermined temperature range may be set with the flame temperature at which nitrogen oxides NOx contained in the combustion exhaust gas do not exceed a preset upper limit value as the target temperature, and the temperature range including the target temperature. For example, the temperature range may be set with the upper and lower limits of 10°C above and below the target temperature centered around the target temperature.

[0081] In addition, the upper limit value of the predetermined temperature range is preferably the upper limit value of the flame temperature during normal operation. During normal operation, sufficient measures are taken for nitrogen oxides contained in the combustion exhaust gas. Therefore, by setting the upper limit value of the flame temperature during normal operation as the upper limit value of the predetermined temperature range, even if there are fluctuations in the operating conditions of the hot blast stove 100, it is possible to prevent the nitrogen oxides contained in the combustion exhaust gas from becoming excessive.

[0082] Also, the type and concentration of combustion products change depending on the mixing ratio. Along with this, the flame temperature changes. The mixing ratio calculation unit 74 can set the flame temperature within a predetermined temperature range by appropriately setting the mixing ratio.

[0083] When the adiabatic flame temperature Tf is outside the predetermined temperature range, the mixing ratio calculation unit 74 acquires the adiabatic flame temperature with the mixing ratio of the coke oven gas to the fuel gas changed.

[0084] Specifically, the mixing ratio calculation unit 74 acquires the adiabatic flame temperature Tf estimated to be within the predetermined temperature range. The mixing ratio calculation unit 74 calculates the mixing ratio corresponding to the adiabatic flame temperature Tf. The mixing ratio calculation unit 74 calculates the mixing ratio of the coke oven gas to the fuel gas until the adiabatic flame temperature Tf is within the predetermined temperature range. When the adiabatic flame temperature Tf is within the predetermined temperature range, the mixing ratio calculation unit 74 stores the mixing ratio in the storage unit 79.

[0085] The mixing ratio setting unit 71 reads out the mixing ratio calculated in the mixing ratio calculation step of step S12 from the storage unit 79. Using the read mixing ratio, the mixing ratio setting unit 71 sets the mixing ratio of the blast furnace gas and the coke oven gas of the fuel gas so that the flame temperature due to the combustion of the mixed gas falls within a predetermined temperature range, and executes a mixing ratio setting step (step S13).

[0086] The calorific value calculation unit 75 executes a calorific value calculation step by calculating the theoretical combustion calorific value as the calorific value (step S14).

[0087] The calorific value is the total amount of thermal energy generated by the combustion of the fuel gas. The total amount of thermal energy generated per unit time by the combustion of the fuel gas can be used as the calorific value.

[0088] The calorific value can be expressed as the product of the calorific value per unit volume of the fuel gas, which is the thermal energy per unit volume of the fuel gas, and the flow rate of the fuel gas supplied per unit time. The greater the calorific value generated in the combustion chamber 10, the greater the sensible heat stored in the regenerator 21.

[0089] In the calorific value calculation step of step S14, the calorific value calculation unit 75 calculates the theoretical combustion calorific value using, for example, the mixing ratio of the coke oven gas to the fuel gas and the flow rate of the fuel gas supplied to the burner 11.

[0090] The calorific value calculation unit 75 calculates the calorific value per unit volume of the fuel gas using the lower calorific value of the blast furnace gas, the lower calorific value of the coke oven gas, and the mixing ratio of the blast furnace gas and the coke oven gas contained in the fuel gas. The calorific value calculation unit 75 calculates the theoretical combustion calorific value by obtaining the product with the flow rate of the fuel gas per unit time supplied from the fuel gas supply system 40.

[0091] The theoretical combustion calorific value can be obtained by the following formula (2) using the lower calorific value of the blast furnace gas, the lower calorific value of the coke oven gas, the mixing ratio of the coke oven gas to the fuel gas, and the flow rate of the fuel gas.

[0092] Ch = {(1 - Br)Cb + Br·Cc} × Vf (2) Here, Ch: Theoretical combustion heat quantity (J / h) Cb: Lower calorific value of blast furnace gas (J / Nm 3 ) Cc: Lower calorific value of coke oven gas (J / Nm 3 ) Br: Volume content ratio of coke oven gas contained in fuel gas (-) Vf: Volume flow rate of fuel gas (Nm 3 / h) Let it be so.

[0093] Next, the flow rate calculation unit 76 calculates the flow rate of the fuel gas so that the theoretical combustion heat quantity obtained in the heat quantity calculation step of step S14 falls within a predetermined range (heat quantity range), and executes the flow rate calculation step (step S15).

[0094] The predetermined range may be determined from the condition of having sufficient thermal energy as the hot blast supplied to the blast furnace and the condition that the heat quantity per unit does not deteriorate by imparting excessive thermal energy.

[0095] For example, the predetermined range of the theoretical combustion heat quantity can be set as the range of the heat quantity that can impart sufficient thermal energy as the hot blast in normal operation. Also, in oxygen enrichment operation, it may be set as the range in which the same heat quantity as that in normal operation is generated even when the mixing ratio of the blast furnace gas and the coke oven gas changes.

[0096] In the flow rate calculation step S15, the flow rate calculation unit 76 calculates the flow rate Vf of the fuel gas such that the theoretical combustion heat quantity Ch falls within a predetermined range using the above formula (2). The calculated flow rate of the fuel gas is stored in the storage unit 79.

[0097] Since the calorific values of the blast furnace gas and the coke oven gas are different, when the mixing ratio of the blast furnace gas and the coke oven gas changes, the calorific value of the fuel gas (heat quantity per unit volume) changes, and the heat quantity generated in the combustion chamber 10 also changes.

[0098] At the mixing ratio setting step of step S13, by adjusting the flow rate of the fuel gas at the mixing ratio of the blast furnace gas and the coke oven gas set, the amount of heat generated in the combustion chamber 10 can be maintained, and the thermal energy of the hot blast supplied to the blast furnace can be ensured.

[0099] The flow rate setting unit 72 executes a flow rate setting step of setting the flow rate of the fuel gas supplied to the burner 11 so that the amount of heat generated by the combustion of the fuel gas falls within a predetermined heat amount range, using the flow rate of the fuel gas calculated in the flow rate calculation step of step S15 (step S16). In the flow rate setting step of step S16, the flow rate of the fuel gas is set while maintaining the mixing ratio of the blast furnace gas and the coke oven gas set in the mixing ratio setting step of step S13.

[0100] The mixing ratio of the blast furnace gas and the coke oven gas set in the mixing ratio setting step of step S13 and the flow rate of the fuel gas set in the flow rate setting step of step S16 are stored in the storage unit 79.

[0101] The fuel gas is supplied to the combustion chamber 10 at the set mixing ratio and the flow rate of the fuel gas as described above, and a combustion step of burning the mixed gas is executed (step S17).

[0102] In the combustion step of step S17, the mixed gas is generated at the set mixing ratio and flow rate as described above and burned in the burner 11. By the way, the nitrogen oxides NOx generated by the combustion of the mixed gas include fuel NOx which becomes nitrogen oxides derived from the nitrogen contained in the fuel gas and thermal NOx which becomes nitrogen oxides derived from the nitrogen contained in the combustion air.

[0103] The coke oven (COG) used for the fuel gas contains relatively many impurities containing nitrogen such as ammonia (NH 3 ) etc. Therefore, when the mixing ratio of the coke oven (COG) in the mixed gas increases, the fuel NOx increases.

[0104] For thermal NOx, the flame temperature of the flame generated by the combustion of the mixed gas has a great influence. Specifically, thermal NOx has the characteristics that the higher the flame temperature, the easier it is to generate, and the longer the time for the fuel gas to pass through the flame, the easier it is to generate.

[0105] When the flame temperature increases by 100°C, the thermal NOx may increase by 60 - 200 ppm. Figure 4 is a diagram showing an example for explaining the relationship between the flame temperature and thermal NOx. As shown in Figure 4, when the flame temperature increases by 100°C, the concentration of thermal NOx contained in the combustion exhaust gas increases from 35 ppm to 110 ppm.

[0106] As described above, since the adiabatic flame temperature is affected by the gas components contained in the fuel gas, it changes depending on the mixing ratio of the blast furnace gas and the coke oven gas that make up the fuel gas. That is, by setting the mixing ratio of the blast furnace gas and the coke oven gas that make up the fuel gas, the flame temperature can be controlled to be within a predetermined temperature range.

[0107] For example, by increasing the flow rate of the fuel gas, the amount of heat increases, so the temperature of the hot blast stove rises. By increasing the mixing ratio of the coke oven gas while keeping the flow rate of the blast furnace gas constant, the amount of heat increases, so the temperature of the hot blast stove rises. As a result, the thermal efficiency of the hot blast stove changes, affecting the heat quantity per unit.

[0108] Also, when the ratio of the supply amount of combustion air to the flow rate of the fuel gas is decreased, carbon monoxide is generated as unburned components in the combustion gas and then in the exhaust gas. Then, the efficiency of the hot blast stove deteriorates due to unburned losses, and the heat quantity per unit deteriorates. The control unit 70 sets the above operating conditions so as to control the thermal efficiency and the heat quantity per unit of the hot blast stove within an appropriate range.

[0109] The operation control flow of the above hot blast stove may be repeated at a predetermined cycle. The predetermined cycle can be set to, for example, 30 to 120 seconds. Incidentally, the operation control of the hot blast stove 100 may end, for example, in synchronization with the timing when the supply of combustion gas ends. Also, the operation control of the hot blast stove 100 may end when the input unit 77 receives an input of measurement completion from the operator and based on this.

[0110] Incidentally, the mixing ratio calculation step in step S12 described above may be executed according to changes in the oxygen concentration of the combustion air during the operation of the hot blast stove 100. In the oxygen enrichment operation, when the flow rate of oxygen supplied from the oxygen supply system 52 fluctuates, the flame temperature changes, and thus the concentration of nitrogen oxides contained in the combustion exhaust gas changes. Therefore, by executing the above control, fluctuations in the concentration of nitrogen oxides contained in the combustion exhaust gas can be suppressed so that excessive nitrogen oxides are not discharged.

[0111] Also, the mixing ratio calculation step in step S12 described above may be executed according to the flow rate of at least one of the blast furnace gas and the coke oven gas during the operation of the hot blast stove 100. Due to fluctuations in the operating states of the blast furnace that supplies blast furnace gas and the coke oven that supplies coke oven gas, the flow rates of the blast furnace gas and the coke oven gas supplied to the hot blast stove 100 may fluctuate.

[0112] In this case, when the mixing ratio of the blast furnace gas and the coke oven gas fluctuates, the flame temperature changes, and the concentration of nitrogen oxides contained in the combustion exhaust gas changes. Therefore, by executing the above control, fluctuations in the concentration of nitrogen oxides contained in the combustion exhaust gas can be suppressed so that excessive nitrogen oxides are not discharged.

[0113] In this way, by setting the mixing ratio according to changes in the oxygen concentration of the combustion air and changes in the flow rate of at least one of the blast furnace gas and the coke oven gas, the concentration of nitrogen oxides in the combustion exhaust gas discharged from the hot blast stove 100 can be adjusted.

[0114] In the above-described embodiment, an example in which the hot blast stove 100 is of an external combustion type in which the combustion chamber 10 and the regenerator 20 are separated has been described.

[0115] The hot blast stove 100 is not limited to an external combustion type, and for example, an internal combustion type, a top combustion type (Kalgin type), or the like may be used. When a top combustion type hot blast stove is used, the burner 11 may be configured with a fuel gas injection nozzle 11a and a combustion air injection nozzle 11b so as to form an in-furnace swirling flow inside the combustion type 12.

[0116] In the present embodiment, an example in which the heat amount calculation step in step S14 to the flow rate setting step in step S16 are executed has been described. However, these steps are steps that can be arbitrarily executed according to the implementation mode.

[0117] Furthermore, in the above-described embodiment, an example in which the adiabatic flame temperature is used as the flame temperature has been described. The temperature of the flame is not limited to the adiabatic flame temperature, and the actually measured temperature may be used. Thus, when measuring the temperature of the flame, it is preferable to use the temperature of the flame that burns in the region of the combustion chamber 10 where the fuel gas and the combustion air are mixed.

[0118] For example, a temperature measurement unit (not shown) for measuring the temperature of the flame may be provided above the combustion chamber 10. The temperature measurement unit is not particularly limited, and examples include those using a contact thermometer measurement method such as a thermocouple or a resistance wire thermometer, and those using a laser speckle method or a flame color reaction method. The control unit 70 is preferably communicably connected to the temperature measurement unit.

[0119] (Second Embodiment) In the above-described embodiment, the flow rate setting step in step S16 has been described with an example of setting the flow rate of the fuel gas using the theoretical combustion heat amount as the heat amount range. In the flow rate setting step, instead of the theoretical combustion heat amount, the temperature of the combustion exhaust gas after the combustion gas of the mixed gas contacts the regenerator may be used to set the flow rate of the fuel gas.

[0120] In this embodiment, an exhaust gas thermometer 62 for measuring the temperature of the combustion exhaust gas after passing through the heat storage body 21 may be used. Further, when executing the flow rate calculation step in step S15, the flow rate calculation unit 76 may set the flow rate of the fuel gas using the temperature of the combustion exhaust gas.

[0121] Specifically, it is preferable to preset a target range for the temperature of the combustion exhaust gas. When the temperature of the combustion exhaust gas is out of the target range, the flow rate setting unit 72 may correct the flow rate of the fuel gas so that the temperature of the combustion exhaust gas approaches the target range.

[0122] For example, the case where the target range of the temperature of the combustion exhaust gas is set to 190 to 210 °C will be described. When the temperature of the combustion exhaust gas is lower than 190 °C, the flow rate setting unit 72 is set to increase the flow rate of the fuel gas. When the temperature of the combustion exhaust gas is higher than 210 °C, the flow rate setting unit 72 is set to decrease the flow rate of the fuel gas.

[0123] The temperature of the combustion exhaust gas is an index that indirectly indicates, for example, the amount of heat generated in the combustion chamber 10 and the heat load of the hot blast stove 100. For example, when there is an error in the flow rate setting of the fuel gas set by the flow rate setting unit 72, by using the temperature of the combustion exhaust gas for correction, it is possible to suppress the heat load of the hot blast stove 100 from becoming excessive.

[0124] The setting of the flow rate of the fuel gas using the temperature of the combustion exhaust gas as described above is preferably performed when the conditions are satisfied a plurality of times within a predetermined period. For example, assuming that after the combustion of the hot blast stove is performed for a predetermined period, the blowing to the heat storage body is performed for a predetermined period as one cycle, and a plurality of cycles are performed. In this case, when it is detected that the temperature of the combustion exhaust gas deviates from the target range in 2 to 5 cycles, the flow rate of the fuel gas may be corrected. By adjusting the flow rate in this way, the stability of the measurement of the temperature of the combustion exhaust gas can be ensured, and the flow rate of the fuel gas can be adjusted in a more appropriate manner.

Example

[0125] Using the hot blast stove described in the first embodiment, an oxygen enrichment operation was performed to examine the relationship between the oxygen concentration of combustion air, the mixing ratio of coke oven gas (COG mixing ratio), and the fuel gas flow rate.

[0126] The blast furnace gas (BFG) had a low calorific value of 810 kcal / Nm 3 and a theoretical air volume of 0.652. The coke oven gas (COG) had a low calorific value of 4205 kcal / Nm 3 and a theoretical air volume of 4.286.

[0127] Both the blast furnace gas and the coke oven gas were at room temperature. The mixing ratio of the blast furnace gas and the coke oven gas and the flow rate of the fuel gas were adjusted by the valve opening degrees of the blast furnace gas flow rate adjustment valve and the coke oven gas flow rate adjustment valve.

[0128] The oxygen concentration of the air supplied from the air supply system 51 was 20.9% by volume. By adjusting the valve opening degrees of the air flow rate adjustment valve and the oxygen flow rate adjustment valve, the amount of oxygen contained in the combustion air and the flow rate of the combustion air were adjusted. Incidentally, preheated combustion air at 175°C was used.

[0129] First, the conditions for normal operation without performing the oxygen enrichment operation of the hot blast stove were set. Specifically, in normal operation, the supply of oxygen from the oxygen supply system was shut off, and the operation was performed with the oxygen concentration of the combustion air equal to that of air.

[0130] Conventional operation know-how has been accumulated for the normal operation of the hot blast stove. Therefore, even if a disturbance occurs in the operation of the hot blast stove, the operation conditions can satisfy the environmental standards as the emission concentration of nitrogen oxides discharged from the hot blast stove. That is, in the normal operation of the hot blast stove, the emission concentration of the discharged nitrogen oxides was 12 ppm as a value converted to 15% O2. In addition, the normal operation of the hot blast stove is an operation condition that can stably supply hot air having the thermal energy necessary for the stable operation of the blast furnace.

[0131] Therefore, in this embodiment, based on the normal operation of the hot blast stove as the reference condition, control was performed to maintain the emission concentration of nitrogen oxides discharged from the hot blast stove and the thermal energy imparted to the hot blast even during oxygen enrichment operation.

[0132] The flame temperature calculation unit created the regression equation represented by the above formula (1) and calculated the adiabatic flame temperature using the regression equation. The heat quantity calculation unit calculated the theoretical combustion heat quantity Ch according to the above formula (2).

[0133] The oxygen concentration of the combustion air used in the oxygen enrichment operation was set to 22 to 28% by volume.

[0134] The adiabatic flame temperature in the normal operation was 1500°C. Correspondingly, the temperature range of the flame temperature in the oxygen enrichment operation was set to a range including 1500°C. Also, the heat quantity in the normal operation was 72.7 Gcal / h. Correspondingly, the range of the predetermined quantity of heat quantity in the oxygen enrichment operation was set to a range including 72.7 Gcal / h.

[0135] Figure 5 shows the relationship between the oxygen concentration of the combustion air in the embodiment, the mixing ratio of the coke oven gas (COG mixing ratio), and the fuel gas flow rate. As shown in Figure 5, the oxygen concentration contained in the combustion air when performing oxygen enrichment operation in the hot blast stove changed between 22 and 28% by volume. The adiabatic flame temperature calculated by the flame temperature calculation unit was 1495 to 1503°C.

[0136] When the oxygen concentration of the combustion air increases, the flame temperature also rises. In order to suppress such an increase in the flame temperature, as shown by the solid line in Figure 5, the mixing ratio of the coke oven gas in the fuel gas decreases. The calorific value of the coke oven gas is lower than that of the blast furnace gas. Therefore, as shown by the dashed line in Figure 5, the fuel gas flow rate increases in order to ensure the heat quantity generated by the combustion of the mixed gas.

[0137] As a result, the nitrogen oxides (NOx) contained in the combustion exhaust gas were 35 ppm, and the oxygen (O2) was 2.9%. The nitrogen oxide concentration converted to 15% O2 was 12 ppm. Also, the amount of heat generated by the combustion of the mixed gas was in the range of 71.0 - 73.3 Gcal / h. The thermal energy required as hot air generated in the hot blast stove could be imparted. That is, in the example, while maintaining the emission concentration of nitrogen oxides discharged from the hot blast stove and the thermal energy imparted to the hot air at the same level as normal operation, the oxygen enrichment operation was realized. Thereby, stable operation and energy saving of the hot blast stove were achieved.

Explanation of Signs

[0138] 100 Hot blast stove 10 Combustion chamber 11 Burner 20 Regenerator 30 Connecting passage 40 Fuel gas supply system 50 Combustion air supply system 70 Control unit 71 Mixing ratio setting unit 72 Flow rate setting unit 73 Flame temperature calculation unit 74 Mixing ratio calculation unit 75 Heat amount calculation unit 76 Flow rate calculation unit

Claims

1. An operation control method for a hot blast stove that burns a mixed gas including fuel gas containing blast furnace gas discharged from a blast furnace and coke oven gas discharged from a coke oven, and combustion air having an oxygen concentration higher than that of air to generate hot blast, comprising: a mixing ratio setting step of setting a mixing ratio of the blast furnace gas and the coke oven gas of the fuel gas according to a temperature range of a flame of the mixed gas; a combustion step of burning the mixed gas at the set mixing ratio, the operation control method of the hot blast stove.

2. a flame temperature calculation step of calculating an adiabatic flame temperature, which is a temperature of combustion gas generated by combustion of the mixed gas; a mixing ratio calculation step of calculating the mixing ratio using the adiabatic flame temperature and the temperature range of the flame, the operation control method of the hot blast stove according to claim 1.

3. The operation control method of the hot blast stove according to claim 1, comprising a flow rate setting step of setting a flow rate of the fuel gas in the mixed gas according to a heat quantity range by combustion of the fuel gas.

4. The operation control method of the hot blast stove according to claim 2, comprising a flow rate setting step of setting a flow rate of the fuel gas in the mixed gas according to a heat quantity range by combustion of the fuel gas.

5. having a heat quantity calculation step of calculating a theoretical combustion heat quantity of the fuel gas; the flow rate setting step sets the flow rate of the fuel gas using the theoretical combustion heat quantity calculated in the heat quantity calculation step as the heat quantity range, the operation control method of the hot blast stove according to claim 3.

6. having a heat quantity calculation step of calculating a theoretical combustion heat quantity of the fuel gas; the flow rate setting step sets the flow rate of the fuel gas using the theoretical combustion heat quantity calculated in the heat quantity calculation step as the heat quantity range, the operation control method of the hot blast stove according to claim 4.

7. In the flow rate setting step, the flow rate of the fuel gas in the mixed gas is set according to a temperature range of combustion exhaust gas after the combustion gas of the mixed gas contacts a regenerator, the operation control method of the hot blast stove according to claim 3.

8. In the flow rate setting step, the flow rate of the fuel gas in the mixed gas is set according to a temperature range of combustion exhaust gas after the combustion gas of the mixed gas contacts a regenerator, the operation control method of the hot blast stove according to claim 4.

9. The operation control method of the hot blast stove according to any one of claims 1 to 8, wherein in the mixing ratio setting step, the mixing ratio corresponding to the oxygen concentration of the combustion air is set.

10. In the mixing ratio setting step, the mixing ratio corresponding to at least one of the flow rates of the blast furnace gas and the coke oven gas is set. The operation control method of the hot blast stove according to any one of claims 1 to 8.

11. A fuel gas supply system that supplies a fuel gas containing blast furnace gas discharged from a blast furnace and coke oven gas discharged from a coke oven to a combustion chamber, a combustion air supply system that supplies combustion air having an oxygen concentration higher than that of air to the combustion chamber, a burner that burns a mixed gas containing the fuel gas and the combustion air in the combustion chamber, a heat storage body that accumulates sensible heat of combustion exhaust gas generated by combustion of the mixed gas, and a wind supply system that supplies wind to the heat storage body. A hot blast stove comprising: A hot blast stove including a mixing ratio setting unit that sets a mixing ratio of the blast furnace gas and the coke oven gas of the fuel gas according to a temperature range of a flame of the mixed gas.

12. Including a flame temperature calculation unit that calculates an adiabatic flame temperature, which is the temperature of combustion gas generated by combustion of the mixed gas. The hot blast stove according to claim 11, wherein the mixing ratio setting unit sets the mixing ratio using the adiabatic flame temperature and the temperature range of the flame.

13. The hot blast stove according to claim 11, including a flow rate setting unit that sets a flow rate of the fuel gas in the mixed gas according to a heat quantity range generated by combustion of the fuel gas.

14. The hot blast stove according to claim 12, including a flow rate setting unit that sets a flow rate of the fuel gas in the mixed gas according to a heat quantity range generated by combustion of the fuel gas.

15. Having a heat quantity calculation unit that calculates a theoretical combustion heat quantity of the fuel gas. The flow rate setting unit sets the flow rate of the fuel gas using the theoretical combustion heat quantity calculated by the heat quantity calculation unit as the heat quantity range. The hot blast stove according to claim 13.

16. Having a heat quantity calculation unit that calculates a theoretical combustion heat quantity of the fuel gas. The hot blast stove according to claim 14, wherein the flow rate setting unit sets the flow rate of the fuel gas using the theoretical combustion heat quantity calculated by the heat quantity calculation unit as the heat quantity range.

17. A hot blast stove operation control program configured to execute each step of the hot blast stove operation control method according to any one of claims 1 to 8 by a computer.

18. A hot blast stove operation control program configured to execute each step of the hot blast stove operation control method according to claim 9 by a computer.

19. A hot blast stove operation control program configured to execute each step of the hot blast stove operation control method according to claim 10 by a computer.

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