Method and control device for combustion of a hot blast furnace

Abstract

To provide a method and device for combustion control of a hot air furnace, capable of suppressing the occurrence of excess heat or insufficient heat in the hot air furnace.SOLUTION: A method for combustion control of a hot air furnace includes: a combustion step of storing heat input by combusting a gas mixture in a heat storage chamber; and a blower step of generating hot air by supplying cold air into the heat storage chamber and then supplying the generated hot air to a blast furnace. The method further includes a step of calculating an actual value of heat quantity, calculating the amount of heat taken away by generating the hot air, calculating an actual value of thermal efficiency of the hot air furnace, calculating the amount of heat to be input when generating hot air next time, calculating the amount of mixed gas to be supplied when generating the next hot air, and controlling the hot air furnace based on the calculated amount of mixed gas.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a combustion control method and a combustion control device for a hot blast furnace that supplies hot air to a blast furnace. [Background technology]

[0002] Patent Document 1 describes a combustion control method for a hot blast furnace that maintains the temperature of the hot air supplied to the blast furnace by compensating for the insufficient combustion time caused by equipment trouble by increasing the amount of input gas. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-226808 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] Even with constant control over the amount of gas supplied to the hot blast furnace, errors such as changes in gas calorific value or a decrease in heat storage capacity due to clogging of the heat storage bricks inside the hot blast furnace can cause overheating or underheating. If overheating occurs, excess gas is supplied to the hot blast furnace, worsening operating costs. On the other hand, if underheating occurs, the blast air temperature decreases, and the furnace temperature of the blast furnace decreases, worsening the furnace conditions.

[0005] The present invention has been made in view of the above problems, and its purpose is to provide a combustion control method and a combustion control device for a hot blast furnace that can suppress the occurrence of excessive heat or insufficient heat in the hot blast furnace. [Means for solving the problem]

[0006] The combustion control method of the hot blast stove according to the present invention includes a combustion step of storing the input heat quantity in the heat storage chamber by burning the mixed gas, and a blowing step of generating hot blast by supplying cold air into the heat storage chamber and supplying the generated hot blast to the blast furnace. The actual value of the heat quantity is calculated as the actual input heat quantity Q ,

[0011] using the following formula (1), and the heat quantity taken away by generating the hot blast is calculated as the actual output heat quantity Q out using the following formula (2). The actual value of the thermal efficiency of the hot blast stove is calculated as the actual thermal efficiency η using the following formula (3), and the heat quantity to be input when generating the next hot blast is calculated as the required input heat quantity Q inHS using the following formula (4). The amount V of the mixed gas to be supplied when generating the next hot blast is calculated using the following formula (5), M_B and the step of controlling the hot blast stove based on the calculated amount V of the mixed gas is included. It is characterized by this.

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[0015] The combustion control method of the hot blast stove according to the present invention is, in the above invention, after the blowing process of the blowing butterfly valve provided between the regenerator and the blower that supplies cold air to the regenerator ends, the correction amount α of the actual heat efficiency η is calculated using the opening degree, and the corrected value η 補正 of the actual heat efficiency η is calculated using the following formula (8), and includes a step of using the calculated corrected value η 補正 in the next process

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[0017] The combustion control device of the hot blast stove according to the present invention is a combustion control device of a hot blast stove having a combustion process of storing the heat quantity input by burning a mixed gas in a regenerator and a blowing process of generating hot blast by supplying cold air into the regenerator and supplying the generated hot blast to a blast furnace. (C bmoi , C Cmoi The definition is unclear), and the actual value of the heat quantity is the actual heat input Q inThe actual heat output Q is calculated as follows, and the amount of heat removed by generating the hot air using the following formula (2) is used. out The actual thermal efficiency of the hot air furnace is calculated as the actual thermal efficiency η using the following formula (3), and the amount of heat to be input when generating hot air next time is calculated as the required input heat Q using the following formula (4). inHS The amount V of the mixed gas to be supplied when generating hot air next time is calculated using the following formula (5). M_B The amount V of the mixed gas is calculated. M_B The system is characterized by comprising means for controlling a hot air furnace based on this.

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[0023] According to the combustion control method and combustion control device for a hot blast furnace of the present invention, it is possible to suppress the occurrence of excessive heat or insufficient heat in the hot blast furnace. [Brief explanation of the drawing]

[0024] [Figure 1] Figure 1 is a schematic diagram showing the configuration of a hot blast furnace, which is one embodiment of the present invention. [Figure 2] Figure 2 is a diagram illustrating the operation of the hot air furnace shown in Figure 1. [Figure 3] Figure 3 is a flowchart showing the flow of a combustion control process, which is one embodiment of the present invention. [Figure 4] Figure 4 is a flowchart showing the flow of the combustion control process when the blower parameters are changed. [Figure 5] Figure 5 shows an example of the daily change in fuel intensity when a combustion control process, which is one embodiment of the present invention, is performed and when it is not performed. [Figure 6] Figure 6 is a flowchart showing a modified version of the combustion control process shown in Figure 3. [Figure 7] Figure 7 shows an example of the relationship between the opening degree of the blower butterfly valve and whether or not the actual thermal efficiency η is corrected. [Figure 8] Figure 8 shows an example of the changes in heat output, heat input, and M gas flow rate when the blast furnace air flow rate decreases after the introduction of the present invention. [Figure 9] Figure 9 shows an example of the relationship between heat output and heat input when there is a decrease in blast furnace airflow rate before and after the introduction of the present invention. [Modes for carrying out the invention]

[0025] Hereinafter, with reference to the drawings, a combustion control method and a combustion control device for a hot blast furnace, which are embodiments of one invention, will be described.

[0026] 〔composition〕 First, the configuration of a hot blast furnace, which is one embodiment of the present invention, will be described with reference to Figures 1 and 2. Figure 1 is a schematic diagram showing the configuration of a hot blast furnace, which is one embodiment of the present invention. Figure 2 is a diagram illustrating the operation of the hot blast furnace shown in Figure 1.

[0027] As shown in Figure 1, a hot blast furnace 1, which is one embodiment of the present invention, is composed of four hot blast furnaces 1a to 1d that supply hot air to a blast furnace 2, and is equipped with combustion blowers 10a to 10c, a heat exchanger 11, an M gas preheater 12, a blower 13, combustion chambers 14a to 14d, and heat storage chambers 15a to 15d. Although the hot blast furnace 1 shown in Figure 1 operates in parallel with the four hot blast furnaces 1a to 1d, the present invention is not limited to this embodiment and can be applied to both internal combustion and external combustion hot blast furnaces.

[0028] The combustion blowers 10a to 10c supply air to the heat exchanger 11.

[0029] The heat exchanger 11 generates combustion air by exchanging heat between the air supplied from the combustion blowers 10a to 10c and the gas (exhaust gas) discharged from the heat storage chambers 15a to 15d, and supplies the generated combustion air to the combustion chambers 14a to 14d.

[0030] The M gas preheater 12 preheats a mixed gas (M gas) such as coke gas or converter gas and supplies it to the combustion chambers 14a to 14d.

[0031] The blower 13 supplies cool air to the heat storage chambers 15a to 15d. The amount of air supplied to the heat storage chambers 15a to 15d can be adjusted by controlling the opening degree of the blower butterfly valves CB1 to CB4, which are installed between the blower 13 and each of the heat storage chambers 15a to 15d.

[0032] In the combustion chambers 14a to 14d, M gas is burned using combustion air supplied from the heat exchanger 11, and the resulting combustion exhaust gas heats the heat storage bricks inside the heat storage chambers 15a to 15d.

[0033] In the heat storage chambers 15a to 15d, the heated heat storage bricks raise the temperature of the cold air supplied from the blower 13 to generate hot air, which is then supplied to the blast furnace 2.

[0034] When supplying hot air to the blast furnace 2 using a hot blast furnace 1 with such a configuration, first, as shown in Figure 2(a), M gas is burned in the combustion chambers 14a to 14d using combustion air supplied from the heat exchanger 11, and the resulting combustion exhaust gas heats the heat storage bricks inside the heat storage chambers 15a to 15d (combustion process). In other words, in the combustion process, heat Q is supplied to the hot blast furnace 1 by heating the heat storage bricks. IN Heat is input (heat stored). Then, as shown in Figure 2(b), in the heat storage chambers 15a to 15d, the heated heat storage bricks raise the temperature of the cold air supplied from the blower 13 to generate hot air, and the generated hot air is supplied to the blast furnace 2 (blowing process). In other words, in the blowing process, the heated heat storage bricks generate hot air, thereby supplying heat quantity Q from the hot air furnace 1. out A fever develops.

[0035] [Combustion control method] In a hot blast furnace 1 with this configuration, a control device configured with a computer or the like performs the combustion control process described below to suppress the occurrence of excess or insufficient heat. The operation of the control device when performing the combustion control process will be explained below with reference to Figure 3.

[0036] Figure 3 is a flowchart showing the flow of a combustion control process according to one embodiment of the present invention. In the flowchart shown in Figure 3, the process begins when the operation of the hot blast furnace 1 is instructed to start, and the combustion control process proceeds to step S1.

[0037] In step S1, the control device starts the combustion process. This completes step S1, and the combustion control process proceeds to step S2.

[0038] In step S2, the control device calculates the actual heat input to the hot blast furnace by integrating the amount of heat input to the hot blast furnace, thereby determining the actual heat input Q. in The calculation is performed as follows. Specifically, the control device uses the following formula (1) to calculate the actual heat input Q. in The control device calculates the actual heat input Q, which is the sum of the M gas input heat, the combustion air latent heat, and the M gas latent heat.in This is calculated as follows. With this, the process in step S2 is completed, and the combustion control process proceeds to the process in step S3.

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[0040] In step S3, the control device terminates the combustion process. This completes step S3, and the combustion control process proceeds to step S4.

[0041] In step S4, the control device starts the blowing process. This completes step S4, and the combustion control process proceeds to step S5.

[0042] In step S5, the control device calculates the actual heat output of the hot blast furnace by integrating the heat output of the hot blast furnace to obtain the actual heat output Q. out The calculation is performed as follows. Specifically, the control device uses the following formula (2) to calculate the actual heat output Q. out The control device calculates the actual heat output Q, which is the sum of the sensible heat of nitrogen, the sensible heat of oxygen, and the sensible heat of moisture in the airflow. out This is calculated as follows. With this, the process in step S5 is completed, and the combustion control process proceeds to the process in step S6.

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[0044] In step S6, the control device terminates the blowing process. This completes step S6, and the combustion control process proceeds to step S7.

[0045] In step S7, the control device calculates the actual heat input Q calculated in step S2. in and the actual heat output Q calculated in the process of step S5 outBy substituting these values ​​into the following formula (3), the actual value of the thermal efficiency η is calculated as the actual thermal efficiency η. This completes the process in step S7, and the combustion control process proceeds to step S8.

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[0047] In step S8, the control device calculates the actual heat output Q calculated in step S5. out By substituting the actual thermal efficiency η calculated in step S7 into the following formula (4), the amount of heat to be fed into the hot blast furnace during the next combustion process is calculated as the required heat input Q. inHS This is calculated as follows. With this, the process in step S8 is completed, and the combustion control process proceeds to the process in step S9.

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[0049] In step S9, the control device calculates the required heat input Q calculated in step S8. inHS By substituting this into the following equation (5), the required heat input Q can be obtained. inHS The flow rate V of M gas required to supply M_B This calculates the value. This completes the process in step S9, and the series of combustion control processes is finished.

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[0051] As is clear from the above explanation, in a combustion control process which is one embodiment of the present invention, the control device uses formula (1) to calculate the actual value of the input heat as the actual heat input Q. in The heat removed by generating hot air using formula (2) is calculated as the actual heat output Q. outThe actual thermal efficiency of the hot air furnace is calculated as the actual thermal efficiency η using formula (3), and the amount of heat to be input when generating hot air next time is calculated as the required input heat Q using formula (4). inHS The amount of mixed gas V to be supplied when generating hot air next time is calculated using formula (5). M_B The amount of the mixed gas V is calculated. M_B Since the hot blast furnace is controlled based on this, it is possible to suppress the occurrence of excessive or insufficient heat in the hot blast furnace.

[0052] Furthermore, when sudden reductions in airflow due to blast furnace conditions or adjustments to the amount of iron produced result in changes to the blast furnace's airflow parameters, the input heat becomes excessive, worsening operating costs. In particular, when sudden reductions in airflow occur, operators manually control the amount of gas input, and due to individual differences among operators, there is a possibility that appropriate gas input control may not be achieved. Here, the blast furnace airflow parameters are as follows: airflow flow rate V b Total O2 flow rate V O2 , air temperature T b , air humidity moi, and cold air temperature T c This can be used as an example. When troubleshooting or adjusting the amount of iron produced, the airflow rate V b As the temperature drops and the hot blast furnace becomes overheated, it becomes necessary to control the amount of heat input to the hot blast furnace.

[0053] Therefore, when the blast furnace blast parameters are changed, it is desirable to control the amount of heat supplied to the hot blast furnace. Specifically, in this case, as shown in the flowchart of Figure 4, the control device first determines whether or not the blast parameters have been changed (step S41). In this embodiment, if the heat output deviation shown in the following formula (9), which is calculated when the blast parameters are changed, is greater than or equal to a predetermined value, the control device determines that the blast parameters have been changed.

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[0055] If the control device determines that the airflow parameters have been changed, it uses the following formula (6) to predict the heat output Q after the airflow parameter change. out予測 The calculated predicted heat output Q out予測 Substituting this into the following equation (7), we obtain the required heat input Q. in予測 The control device then calculates the required heat input Q. in予測 Based on this, the flow rate of M gas to be introduced into the hot blast furnace is calculated (step S43).

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[0058] [Thermal efficiency correction] Figure 5 shows an example of the daily change in fuel intensity when a combustion control process, which is one embodiment of the present invention, is performed and when it is not. As shown in Figure 5, it was confirmed that the fuel intensity decreases when the combustion control process, which is one embodiment of the present invention, is performed. However, even when the combustion control process, which is one embodiment of the present invention, is performed, there were days when the fuel intensity decreased significantly and days when it decreased only slightly. Therefore, the inventors of the present invention investigated in detail the operational details on days when the fuel intensity decreased only slightly. As a result, they found that the fuel intensity tends to decrease only slightly on days when the blast flow rate is reduced to adjust the amount of blast furnace production and on days when the reduced blast flow rate is restored to its original level. This is thought to be because the furnace temperature state of the hot blast furnace differs from normal conditions during non-steady-state operations.

[0059] Therefore, it is desirable to correct the value of the thermal efficiency η using the opening degrees of the blower butterfly valves CB1 to CB4 at the end of the blowing process as a criterion for determining the furnace heat state. Specifically, in parallel operation with four hot blast furnaces 1a to 1d, the heat content of the preceding furnace decreases over time, so the blower butterfly valve corresponding to the preceding furnace is gradually closed, and the blower butterfly valve opening of the subsequent furnace, which has sufficient furnace heat, is opened to control the blower temperature to remain constant. Therefore, the furnace heat state of the hot blast furnace after the end of the blowing process can be estimated from the opening degrees of the blower butterfly valves. For example, if the opening degree of the blower butterfly valve at the end of the blowing process is large, it is thought that heat remains in the hot blast furnace even after the blowing process is finished, and that more heat than necessary was input during the previous combustion process. If the opening degree of the blower butterfly valve is large, the hot blast furnace is in a state of excess heat, and if the amount of heat input during the next combustion process becomes excessive, the thermal efficiency will deteriorate. On the other hand, if the opening of the blower butterfly valve is small, the hot blast furnace will not have enough heat, making it impossible to maintain the set blower temperature, which could negatively affect blast furnace operation.

[0060] Therefore, as shown in the flowchart of Figure 6, the control device calculates the actual thermal efficiency η in step S27 and then determines whether or not it is necessary to correct the actual thermal efficiency η based on the opening degree of the blower butterfly valve (step S28). In this embodiment, as shown in Figure 7, the lower limit opening degree B2, lower limit opening degree B1, upper limit opening degree A1, and upper limit opening degree A2 are set for the opening degree of the blower butterfly valve at the end of the blowing process. The control device determines whether or not it is necessary to correct the actual thermal efficiency η based on the opening degree of the blower butterfly valve based on the opening degree of the blower butterfly valve based on the range shown in Figure 6. If it is determined that a correction of the actual thermal efficiency η is necessary (step S28: Yes), the control device corrects the actual thermal efficiency η based on the opening degree of the blower butterfly valve.

[0061] Specifically, when the opening of the blower butterfly valve is small, the control device uses the following formula (8) to add a negative correction value α to the thermal efficiency η and increases the amount of M gas to be introduced next time to compensate for the heat deficiency. On the other hand, when the opening of the blower butterfly valve is large, the control device uses the following formula (8) to add a positive correction value α to the thermal efficiency η and decreases the amount of M gas introduced next time to suppress the deterioration of thermal efficiency due to excess heat and the surplus introduction of M gas. On the other hand, if it is determined that correction of the actual thermal efficiency η is unnecessary (step S28: No), the control device proceeds to step S30 of the combustion control process. Note that the contents of steps S21 to S27 and steps S30 to S31 shown in Figure 6 are the same as the contents of steps S1 to S9 shown in Figure 3, so their explanation is omitted.

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[0063] [Examples] In this example, the volume is 4500 m³. 3 The blast furnace has a rated airflow of 7000 Nm³. 3The present invention was applied to an operation supplying hot air from four hot blast furnaces with a rated heat input of 9000-10000 MJ / min. Figures 8(a)-(d) show an example of the changes in heat output, heat input, and M gas flow rate when the blast furnace blast flow rate is reduced after the introduction of the present invention. In the example shown in Figures 8(a)-(d), a correction was made for thermal efficiency η: 1.5% at a blower butterfly valve opening of 65% and for thermal efficiency η: -7.0% at a blower butterfly valve opening of 50%. As shown in Figures 8(a)-(d), the heat input decreases along with the decrease in heat output due to the reduction in blast furnace blast flow rate. This confirms that, according to the present invention, M gas and operating costs can be reduced in accordance with the change in heat output. Figures 9(a) and 9(b) also show an example of the relationship between heat output and heat input when the blast furnace blast flow rate is reduced before and after the introduction of the present invention. As shown in Figure 9(a), before the introduction of the present invention, there were cases (region R1) where the heat input could not be reduced in accordance with a decrease in heat output due to individual differences among operators. In contrast, as shown in Figure 9(b), it was confirmed that after the introduction of the present invention, the heat input could be reduced in accordance with the decrease in heat output.

[0064] Although embodiments applying the invention made by the present inventors have been described above, the present invention is not limited by the descriptions and drawings that constitute part of the disclosure of the present invention in this embodiment. That is, all other embodiments, examples, and operational techniques made by those skilled in the art based on this embodiment are included in the scope of the present invention. [Explanation of Symbols]

[0065] 1,1a,1b,1c,1d hot stove 2 blast furnace 11 Heat exchanger 12 M gas preheater 13 Blower 14a, 14b, 14c, 14d Combustion chamber 15a,15b,15c,15d Heat storage room CB1, CB2, CB3, CB4 Blower Butterfly Valve

Claims

1. A combustion control method for a hot blast furnace, comprising a combustion step of storing the amount of heat input in a heat storage chamber by burning a mixed gas, and a blowing step of generating hot air by supplying cold air into the heat storage chamber and supplying the generated hot air to the blast furnace, Using the following formula (1), the actual value of the heat quantity is calculated as the actual heat input Q. ｉｎ The actual heat output Q is calculated as follows, and the amount of heat removed by generating the hot air using the following formula (2) is used. ｏｕｔ The actual thermal efficiency of the hot air furnace is calculated as the actual thermal efficiency η using the following formula (3), and the amount of heat to be input when generating hot air next time is calculated as the required input heat Q using the following formula (4). inHS The amount V of the mixed gas to be supplied when generating hot air next time is calculated using the following formula (5). Ｍ＿Ｂ The amount V of the mixed gas is calculated. Ｍ＿Ｂ A method for controlling the combustion of a hot blast furnace, characterized by including the step of controlling the hot blast furnace based on [a certain condition]. [Math 1] [Math 2] [Math 3] [Math 4] [Math 5]

2. If the blowing parameters of the blast furnace are changed, the amount of heat removed by generating the hot air is predicted using the following formula (6) Q. ｏｕｔ予測 The following formula (7) is used to calculate the predicted value Q of heat. ｏｕｔ予測 The combustion control method for a hot blast furnace according to claim 1, characterized by including the step of calculating the amount of heat required to obtain a heat input as a predicted required heat input Qin, and controlling the hot blast furnace based on the calculated predicted required heat input Qin. [Math 6] [Number 7]

3. After the blowing process of the blowing butterfly valve provided between the regenerator and the blower for supplying cold air to the regenerator ends, the correction amount α of the actual heat efficiency η is calculated, and the corrected value η of the actual heat efficiency η is calculated using the following mathematical formula (8). 補正 is calculated, and the calculated corrected value η 補正 is used in the next process, and the combustion control method of the hot blast stove according to claim 1 or 2 is characterized by including this step. [Number 8]

4. A combustion control device for a hot blast furnace, comprising a combustion step of storing the amount of heat input in a heat storage chamber by burning a mixed gas, and a blowing step of generating hot air by supplying cold air into the heat storage chamber and supplying the generated hot air to a blast furnace, Using the following formula (1), the actual value of the heat quantity is calculated as the actual heat input Q. ｉｎ The actual heat output Q is calculated as follows, and the amount of heat removed by generating the hot air using the following formula (2) is used. ｏｕｔ The actual thermal efficiency of the hot air furnace is calculated as the actual thermal efficiency η using the following formula (3), and the amount of heat to be input when generating hot air next time is calculated as the required input heat Q using the following formula (4). inHS The amount V of the mixed gas to be supplied when generating hot air next time is calculated using the following formula (5). Ｍ＿Ｂ The amount V of the mixed gas is calculated. Ｍ＿Ｂ A combustion control device for a hot blast furnace, characterized by comprising means for controlling the hot blast furnace based on [the specified criteria]. [Number 9] [Number 10] [Math 11] [Math 12] [Number 13]

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