JP2013095946A - Combustion control method and combustion control device for hot stove - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control method which suppresses decrease of thermal efficiency, when a load of a hot stove changes.SOLUTION: In a combustion control device 104, using data comprising an index showing a heat level at a ventilation period in each hot stove, an index showing a thermal load in each hot stove, and an index showing a thermal margin in each hot stove, a model is designed giving a relation established between these indexes for each hot stove. The values of the index showing the thermal load and the index showing the thermal margin are set for each hot stove. The set values are input into the model of each hot stove. A target value of the heat level of each hot stove is calculated. A heat quantity of being input into a regenerator part of each hot stove is controlled so as to coincide with the target value of the heat level of each hot stove asymptotically. As a result, the decrease of thermal efficiency is suppressed when the load of the hot stove changes.

Description

  The present invention relates to a combustion control method and a combustion control device for a hot stove for supplying hot air to a blast furnace.

  In the hot air furnace, during the combustion period, the heat storage part in the furnace is heated by the combustion gas to accumulate thermal energy, and in the blowing period following the combustion period, hot air is generated by heat exchange with the heat storage part through cold air in the furnace. This is a facility for supplying the generated hot air to the blast furnace. In such a hot stove, during the combustion period, it is necessary to input a heat quantity necessary for ensuring a desired hot air temperature into the heat storage section during the subsequent blowing period. However, in order to realize energy saving and reduction of carbon dioxide emission, it is desirable to suppress the heat input to the heat storage unit as much as possible.

  On the other hand, the silica brick constituting the heat storage part may expand rapidly and collapse when the temperature falls below 573 ° C. which is the transformation point temperature. For this reason, it is necessary to adjust the amount of heat input to the heat storage unit so that the temperature of the silica brick becomes equal to or higher than the transformation point temperature even at the end of the blowing period. In addition, from the viewpoint of equipment protection, the dome that is the top of the hot stove cannot be heated above a certain temperature. For this reason, it is desirable to minimize the amount of heat input to the heat storage section under the above-described constraints.

  In the operation of the hot stove, a single operation of mixing hot air from one hot stove and cold air to adjust the temperature and supplying hot air to the blast furnace, and two of at least three hot stoves There is a staggered parallel operation in which time is passed through a hot blast furnace at the same time and the obtained hot blast is mixed and supplied to the blast furnace. FIG. 9 is a conceptual diagram of staggered parallel operation. In FIG. 9, a parameter k indicates a discretized time and is made coincident with the furnace switching time. Hereinafter, the interval between hot stove switching times is referred to as a period.

  In the example shown in FIG. 9, the hot stove (1HS) finishes the blowing period and enters the combustion period at time k = 0. The hot stove (2HS) finishes the blowing period and enters the combustion period at time k = 1 with a delay of one period. The hot stove (3HS) ends the combustion period and enters the blowing period at time k = 0. The hot stove (4HS) ends the combustion period at time k = 1 after one period and enters the blowing period. For this reason, between the time k = 1 and the time k = 2, two hot stoves, a hot stove (3HS) and a hot stove (4HS), will be in a ventilation state. In addition, between the time k = 1 and the time k = 2, the hot stove (3HS) is a follower of the hot stove (2HS) and has a higher heat level than the preceding hot stove (2HS). Plays the role of supplying hot hot air.

  Therefore, at the time k = 1, it is important that the temperature of the hot air from the hot stove (3HS) is higher than the setting value of the blowing temperature to the blast furnace. For this reason, at time k = 1, the hot air from the hot stove (3HS) and the hot stove (4HS) are both higher than the blow temperature setting value. Therefore, the hot stove (4HS) waits until the time when the hot air temperature from the hot stove (3HS) decreases to the set air temperature (indicated by symbol A in FIG. 9), during which only the hot stove (3HS) is blown. The air temperature is controlled by mixing the cold air with the hot air from the hot stove (3HS).

  In the case of single operation, the temperature of hot air from each hot stove must always be higher than the set air temperature. On the other hand, in the case of staggered parallel operation, hot air from a preceding furnace whose temperature is lower than the blower temperature set value and hot air from a subsequent furnace whose temperature is higher than the blower temperature set value are mixed and used. . For this reason, the staggered parallel operation can lower the level of the heat storage amount (hereinafter referred to as the heat level) as compared with the single operation, and can increase the thermal efficiency. Thereby, when supplying hot air to a large blast furnace, a staggered parallel operation is generally performed.

  In the conventional hot stove combustion control method, the heat level of the hot stove after one cycle consisting of the combustion period and the air blowing period is calculated, and the next input heat amount is determined based on the calculated heat level. Is common. For example, in Patent Documents 1 and 2, the heat level of the hot stove at the end of the air blowing, the change in the heat level, and the temperature of the quartz brick are converted into a determination function based on fuzzy inference, and each measured value based on the fuzzy inference Describes a method of determining the operation amount and the input heat amount from the above.

  Patent Document 3 calculates the heat level after the end of air blowing several cycles ahead using a hot stove simulator, and calculates the thermal trend index indicating whether the heat ahead state or the heat shortage state is several cycles ahead. A method for correcting the input heat quantity based on the current heat level and the thermal tendency index is described. Further, Patent Document 4 monitors the deviation between the heat level at a certain point in the blowing period and its target value, and performs fuzzy inference when the deviation is larger than the set value, and optimum feedback control when the deviation is less than the set value. A method is described in which the exhaust gas temperature final value in the combustion period is calculated, and the input heat amount is controlled based on the calculated exhaust gas temperature final value.

Japanese Patent Publication No. 6-37651 Japanese Patent Publication No. 7-100806 Japanese Patent Laid-Open No. 10-226809 Japanese Patent Laid-Open No. 1-319619

  By the way, in the staggered parallel operation, since the two hot air furnaces are simultaneously ventilated, the amount of thermal energy that the subsequent furnace should give to the cold air varies depending on the heat level of the preceding furnace. For example, if the heat level of the preceding furnace is high, the timing at which ventilation to the succeeding furnace is started (point A in the case of the hot stove (4HS) in FIG. 9) is delayed, and the substantial blowing period is shortened. The minute furnace does not use heat energy and is in a state of surplus heat. And it propagates to the heat level of the next hot stove and the tendency of excess heat continues. On the other hand, when a certain hot stove is in a heat-deficient state, it propagates to the subsequent hot-blast stove, and the tendency of heat shortage continues. In staggered parallel operation, due to such interference between hot stoves, it takes a few days for the heat level to reach a steady state when changing the input heat quantity, and there is no interference between hot stoves. Compared with, the response of the whole system becomes very slow.

  For example, when the blast temperature set value increases, the amount of heat lost by the hot stove during the blast period increases, so that the heat level decreases, and if it spreads to the subsequent hot stove, there is a possibility that a sufficient amount of heat cannot be supplied. For this reason, it is necessary to provide a margin for the heat level of each hot stove so as to cope with such load fluctuations. On the other hand, operating at a high heat level means that the amount of heat input is large, and the excessive amount of heat causes an increase in the amount of heat dissipated from the hot-blast furnace body and an upper layer of the exhaust gas temperature, resulting in a decrease in thermal efficiency. Therefore, in the combustion control of the hot stove, it is important to maintain the heat level appropriately by manipulating the input heat amount so that the heat does not become insufficient or excessive.

  In order to keep the heat level appropriate, it is necessary to appropriately set the heat level target value in the combustion control. That is, when the load of the hot stove is high, in other words, when the blowing temperature is high and the blowing flow rate is large, the heat level target value is set high, and when the load of the hot stove is low, in other words, the blowing temperature is When the air flow rate is low and the air flow rate is small, it is necessary to set the heat level target value low. However, the techniques described in Patent Documents 1 to 4 do not disclose or suggest any method for setting the target value of the heat level. This is considered to be because in fuzzy control, whether the heat level is high, appropriate, or low is expressed by a membership function, and the concept of target value is thin. For this reason, according to the techniques described in Patent Documents 1 to 4, when the load of the hot stove fluctuates, it is not possible to set an appropriate heat level target value, and as a result, when the load is high, heat is insufficient. When the load is low, the heat efficiency decreases due to excessive heat. For this reason, provision of the technique which suppresses that thermal efficiency falls when the load of a hot stove is fluctuated by setting a heat level target value appropriately was anticipated.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a combustion control method and a combustion control device for a hot stove capable of suppressing a decrease in thermal efficiency when the load of the hot stove is fluctuated. There is to do.

  In order to solve the above-mentioned problems and achieve the object, a combustion control method for a hot stove according to the present invention accumulates thermal energy by raising the temperature of a heat storage section in the furnace with combustion gas in a plurality of hot stoves. A combustion control method for a hot air furnace that supplies hot air to a blast furnace by repeatedly executing a combustion period and an air blowing period in which hot air is generated by exchanging heat with the heat storage unit through cold air in the furnace. Using the data of the index representing the heat level in the period, the index representing the thermal load of each hot stove, and the index representing the thermal margin of each hot stove, a model representing the relationship between these indices is used. The value of the step to be constructed for each, the index indicating the heat load and the index indicating the thermal margin is set for each hot stove, and the set value is input to the model of each hot stove, thereby Step to calculate the target value of the level And flop, heat level of the hot air oven is characterized in that it comprises a step of controlling the heat input to the heat storage unit of the hot air oven to asymptotically coincides with the target value.

  In the hot stove control method according to the present invention, in the above invention, the index representing the heat level is a dome temperature at the end of the blowing period of each hot stove, and the index representing the thermal load is a temperature of hot air blown to the blast furnace. The index representing the thermal margin is the cold-air butterfly valve opening degree of the succeeding furnace of each hot stove at the end of the blowing period of each hot stove.

  In order to solve the above-described problems and achieve the object, a combustion control apparatus for a hot stove according to the present invention accumulates thermal energy by raising the temperature of a heat storage section in the furnace with combustion gas in a plurality of hot stoves. A combustion control device for a hot air furnace that supplies hot air to a blast furnace by repeatedly executing a combustion period and an air blowing period in which hot air is generated by exchanging heat with the heat storage unit through cold air in the furnace. Using the data of the index representing the heat level in the period, the index representing the thermal load of each hot stove, and the index representing the thermal margin of each hot stove, a model representing the relationship between these indices is used. Each hot stove is configured by setting a value of a model building unit to be built for each hot stove, and an index representing a thermal load and an index representing a thermal margin for each hot stove, and inputting the set values into the model of each hot stove. The target value of the heat level of A standard value setting unit and an input heat amount setting unit that controls the input heat amount to the heat storage unit of each hot stove so that the heat level of each hot stove asymptotically matches the target value are provided. .

  According to the combustion control method and combustion control apparatus for a hot stove according to the present invention, it is possible to suppress a decrease in thermal efficiency when the load of the hot stove varies.

FIG. 1 is a schematic diagram showing a configuration of a hot air supply system to which the present invention is applied. FIG. 2 is a schematic diagram showing the configuration of the hot stove shown in FIG. FIG. 3 is a block diagram showing a configuration of a combustion control system for a hot stove as an embodiment of the present invention. FIG. 4 is a diagram showing an example of operation result data stored in the operation result database shown in FIG. FIG. 5 is a flowchart showing the flow of combustion control processing for a hot stove according to an embodiment of the present invention. FIG. 6 is a diagram for explaining operation data extraction timing. FIG. 7 is a diagram in which the horizontal axis represents the dome temperature, the vertical axis represents the blast temperature, and the cold air butterfly valve opening is indicated by contour lines. FIG. 8 is a diagram for explaining a method for setting the dome temperature target value. FIG. 9 is a conceptual diagram of staggered parallel operation.

[Concept of the present invention]
The heat level of the hot stove is determined by the balance between the amount of heat gained during the combustion period and the amount of heat lost during the blowing period. In the prior art, the dome temperature, the quartz brick joint temperature, the cold air butterfly valve opening, the amount of mixed cold air, and the deviation between the hot air temperature from each hot air furnace and the set air temperature are used as indices representing the heat level. The amount of heat input during the combustion period was adjusted using one of these as a controlled variable. However, the appropriate values of the indexes representing these heat levels include those that vary depending on the temperature and flow rate of the blast furnace, that is, the load of the hot stove, and may be constant regardless of the load of the hot stove. There is.

  Specifically, the appropriate value of the hot air temperature from each hot stove varies depending on the blowing temperature. The silica brick temperature in the hot stove directly affects the air blowing temperature. For this reason, the appropriate values of the dome temperature and the quartz brick joint temperature vary depending on the blowing temperature. Therefore, the dome temperature and the quartz brick joint temperature are direct indicators representing the heat level of the hot stove, and the appropriate values vary depending on the load of the hot stove. Thereby, it is necessary to change the target values of these indexes in response to changes in the target values of the blast furnace temperature and the blast flow rate.

  On the other hand, the cold air butterfly valve opening is an index indicating how much heat remains in the hot air furnace after supplying hot air at the temperature and flow rate required from the blast furnace, and its appropriate value is the value of the hot air furnace. Independent of load. Similarly, the amount of mixed cold air is the amount of cold air mixed with the hot air from the hot air furnace in order to supply the hot air having the temperature and flow rate required from the blast furnace, and its proper value does not depend on the load of the hot air furnace. In other words, the amount of cold air butterfly valve opening and the amount of mixed cold air is greater than the minimum amount of heat required for supplying hot air at the temperature and flow rate required from the blast furnace. In other words, it is an index representing the heat margin, and therefore does not depend on the load of the hot stove.

  For example, when the target value of the blast furnace air temperature is lowered and the load of the hot stove is reduced, the heat margin increases if the supply heat quantity in the combustion phase is not changed, the mixed cold air quantity increases, the dome temperature and the quartz brick The seam temperature increases. Here, when the supply heat quantity in the combustion period is adjusted so that the mixed cold air quantity becomes the original level, the dome temperature and the quartz brick joint temperature are lowered from the original level. This is because the brick temperature may be low if the blowing temperature is low. Therefore, it seems that combustion control can be performed regardless of the load of the hot stove furnace by manipulating the amount of heat supplied to the hot stove using the index of heat margin such as the amount of cold air mixture as the control amount. However, the heat margin does not represent the absolute value of the heat level of the hot stove, but represents the balance between the amount of heat supplied to the hot stove during the combustion phase and the amount of heat lost by the hot stove during the blowing phase. Setting as a control amount of control is not preferable. That is, as the control amount of the combustion control, one that directly represents the absolute amount of the furnace heat bell such as the brick temperature should be used.

  Therefore, the inventors of the present invention provide an index of the load of the hot stove and an index of the thermal margin of the hot stove where the appropriate value does not change depending on the load of the hot stove, and the heat of the hot stove where the appropriate value changes depending on the load of the hot stove. Obtain a model that represents the relationship with the level index, and calculate the target value for the thermal level of the hot stove by setting the index of the hot stove load and the index of the thermal margin of the hot stove in the obtained model. The technical idea of performing combustion control so as to make the heat level of the hot stove coincide with the target value of the obtained heat level was conceived. According to such a technical idea, the target value of the heat level of the hot stove can be appropriately set in consideration of both the load and the heat margin of the hot stove.

  Specifically, if you want to keep the thermal margin constant even if the blast temperature target value changes, adjust the load index of the hot stove to the blast temperature target value while maintaining the thermal margin index setting. Change it. Also, if the target air temperature is changed frequently and there is not enough heat margin to follow the heat level of the hot stove, the target value of the air temperature can be changed by increasing only the set value of the heat margin index. It is also possible to increase the margin for. Since the target value of the heat level can be set according to various conditions such as the load and heat margin of the hot stove, the amount of heat input to the hot stove is optimized by performing combustion control according to the target value of the heat level. To save energy and reduce carbon dioxide emissions.

  As a model construction method, it is also possible to simulate the operation of the hot stove using a hot stove physical model and derive the relationship between the load of the hot stove, the heat level of the hot stove, and the thermal margin of the hot stove. However, it is desirable to obtain a statistical model that represents the relationship between the load of the hot stove, the heat level of the hot stove, and the thermal margin of the hot stove using past operation data. In this case, the simplest model is a linear meter regression model, but a combination of past operation results data and the thermal margin of the hot stove, and a combination of the current hot stove load index and the desired thermal margin index. And using a local regression model that performs regression with a greater weight for data that is more similar to each other, it is possible to express a non-linear relationship and improve model accuracy. In addition, similar data can be given a greater weight, and the average value of the thermal level performance of the hot stove in the operation performance data can be obtained and used as a target value for the heat level. Non-linear relationships can be expressed, and the accuracy of the model can be improved. Moreover, by taking two indices in the orthogonal coordinate system and displaying the remaining one index on the coordinates with a color map or contour lines among the indices of the load, heat level, and thermal margin of the hot stove, three indices The relationship may be displayed visually in an easy-to-understand manner. Thereby, the target value setting of a heat level can be made easy.

  Hereinafter, a hot stove combustion control method and a combustion control method, which are one embodiment of the present invention conceived based on the above technical idea, will be described with reference to the drawings.

[Configuration of hot air supply system]
First, the configuration of a hot air supply system to which the present invention is applied will be described with reference to FIGS.

  FIG. 1 is a schematic diagram showing a configuration of a hot air supply system to which the present invention is applied. As shown in FIG. 1, a hot stove supply system 1 to which the present invention is applied includes a plurality of hot stoves 10. Each hot air furnace 10 heats up the heat storage chamber in the furnace with the combustion gas in the combustion period to accumulate thermal energy, and in the blowing period subsequent to the combustion period, the hot air is supplied by heat exchange with the heat storage chamber through cold air in the furnace. And the generated hot air is supplied to the blast furnace 20. The blast furnace 20 is supplied with hot air having a temperature and a flow rate necessary for blast furnace operation by shifting the combustion period and the blast period between the plurality of hot blast furnaces 10 and repeatedly executing the combustion period and the blast period cycles. be able to.

  In the hot air supply system 1 shown in FIG. 1, there are a case where cool air is passed through only one hot air furnace 10 and a case where cold air is passed simultaneously through two hot air furnaces 10 in the ventilation period. In the former, by adjusting the opening degree of the mixed butterfly valve 21 for supplying the cold air to the blast furnace 20 and the cold air butterfly valve 22 for supplying the cold air to one hot air furnace 10, the cold air and the hot air are mixed and desired. Realize hot air temperature. On the other hand, in the latter case, the opening degree of the cold air butterfly valve 22 for supplying the cold air to one hot air furnace 10 is fully opened, and the opening degree of the cold air butterfly valve 22 for supplying the cold air to the other hot air furnace 10 is adjusted. The hot air from the two hot air furnaces 10 is mixed to achieve a desired hot air temperature. The opening degree of each butterfly valve is controlled by the air temperature control unit 24 based on the temperature of the hot air (air temperature) at the tuyere of the blast furnace 20 measured by the air temperature measuring unit 23.

  FIG. 2 is a schematic diagram showing the configuration of the hot stove 10 shown in FIG. The hot stove 10 includes a combustion chamber 11 and a heat storage chamber 12. The combustion chamber 11 burns fuel gas supplied from the fuel gas supply port 13 and combustion air supplied from the combustion air supply port 14 in the combustion period, and combustion generated by combustion through the dome portion 15. Gas is supplied to the heat storage chamber 12. Silica brick 16 is stacked inside the heat storage chamber 12, and the combustion gas supplied from the combustion chamber 11 heats the silica brick 16. The heat storage chamber 12 supplies cold air to the inside from the cold air supply port 17 and generates hot air by heat exchange between the quartz brick 16 and the cold air in the blowing period following the combustion period.

[Composition of combustion control system]
Next, the configuration of a combustion control system for a hot stove that is an embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a block diagram showing a configuration of a combustion control system for a hot stove as an embodiment of the present invention. FIG. 4 is a diagram illustrating an example of operation result data stored in the operation result database 103 illustrated in FIG. 3.

  As shown in FIG. 3, the combustion control system 100 according to one embodiment of the present invention includes a blower temperature measurement unit 23, a dome temperature measurement unit 101, a cold air butterfly valve opening measurement unit 102, an operation result database 103, and a combustion control device. 104 and a combustion gas flow rate adjustment unit 105. The blast temperature measuring unit 23 measures the temperature of the hot air (blast temperature) supplied to the blast furnace 20 (see FIG. 1), and outputs a signal indicating the measured temperature to the combustion control device 104. The dome temperature measurement unit 101 measures the temperature (dome temperature) of the dome unit 15 (see FIG. 2), and outputs a signal indicating the measured temperature to the combustion control device 104.

  The cold air butterfly valve opening degree measurement unit 102 detects the opening degree of the cold air butterfly valve 22 (see FIG. 1) that controls the flow rate of the cold air for each hot stove 10, and generates a signal indicating the detected opening degree in the combustion control device 104. Is output. The operation result database 103 stores data related to past operations of each hot stove 10 as operation result data. Specifically, as shown in FIG. 4, the operation data includes the hot blast furnace 10 and the dome temperature at the end of the blowing period, the cold-air butterfly valve opening degree of the succeeding furnace at the end of the blowing period, and the blast furnace. Includes data on air temperature to

  The combustion control device 104 is configured by an information processing device such as a personal computer or a microcomputer. The combustion control device 104 functions as a model construction unit 104a, a dome temperature target value setting unit 104b, and an input heat amount setting unit 104b when an arithmetic processing device such as a CPU in the information processing device executes a computer program. The functions of these units will be described later. The combustion gas flow rate control unit 105 controls the flow rate of the combustion gas by controlling the flow rate of the fuel gas supplied from the fuel gas supply port 13 to the combustion chamber 11 in accordance with a control signal from the combustion control device 104.

  Combustion control system 100 having such a configuration suppresses a decrease in thermal efficiency when the load of each hot stove 10 is fluctuated by executing the following combustion control process. The operation of the combustion control system 100 when executing this combustion control process will be described below with reference to the flowchart shown in FIG.

[Combustion control processing]
FIG. 5 is a flowchart showing the flow of combustion control processing for a hot stove according to an embodiment of the present invention. The flowchart shown in FIG. 5 starts at the timing when the operation of the hot air supply system 1 is started, and the combustion control process proceeds to the process of step S1. This combustion control process is repeatedly executed every predetermined control cycle.

  In the process of step S1, the model construction unit 104a constructs a model that represents the relationship between the index of the load of the hot stove, the index of the thermal margin of the hot stove, and the index of the heat level of the hot stove. In this embodiment, the blast furnace temperature as an index of the hot stove load, the cool air butterfly valve opening degree of the succeeding furnace at the end of the blast period, and the heat level of the hot stove as an index of the thermal margin of the hot stove The dome temperature at the end of the blowing period is used as an index. That is, if there is still room in the heat of the preceding furnace at the timing when the preceding furnace has finished blowing, the amount of heat given to the cold air by the preceding furnace increases and the amount of ventilation to the succeeding furnace decreases. The cold air butterfly valve opening becomes smaller.

  Further, if the thermal margin of the preceding furnace is very large, hot air can be supplied only by the preceding furnace until the end of the blowing period, so that the cold-air butterfly valve opening degree of the succeeding furnace becomes very small, and the state becomes close to single operation. On the other hand, when the heat margin of the preceding furnace is small, the amount of heat to be supplied from the succeeding furnace is increased, so that the cold air butterfly valve opening degree of the succeeding furnace is increased. For this reason, the cold-air butterfly valve opening degree of the succeeding furnace at the end of the blowing period can be used as an index of the thermal margin that does not depend on the load of the hot-air furnace. Further, the dome temperature at the end of the blowing period represents the heat level of the preceding furnace, but the appropriate value depends on the load of the hot stove.

  Further, in the present embodiment, the model construction unit 104 a uses the operation result data stored in the operation result database 103 in order to cope with the difference in the characteristics of each hot stove 10, and creates a model for each hot stove 10. To construct. A local average model is used as a model to be constructed. Specifically, the model construction unit 104a extracts a set of the blowing temperature (i), the cold air butterfly valve opening (i), and the dome temperature (i) from the operation result data for each hot stove main body 10. Note that i indicates a data number, and in the present embodiment, i is an integer from 1 to 1000.

  FIG. 6 is a diagram for explaining operation data extraction timing. As shown in FIG. 6, the operation result data of the hot stove (2HS) includes the dome temperature (indicated by a point P1) and hot air of the hot stove (2HS) at the time k = 1 when the hot stove (2HS) ends blowing. The cold-air butterfly valve opening (indicated by point P2) of the furnace (3HS) is collected, and then collected again at time k = 5 when the hot air furnace ends blowing (indicated by point P3 and point P4). Similarly, necessary operation performance data can be obtained by repeatedly collecting data at the time when the heating furnace (2HS) ends blowing.

  When the set of the blowing temperature (i), the cold air butterfly valve opening (i), and the dome temperature (i) is extracted from the operation result data, the model construction unit 104a sets the current time to j and the current blowing temperature to the blowing temperature ( j) A model represented by the following formulas (1) to (3) is constructed with the current cold air butterfly valve opening as the cold air butterfly valve opening (j). It should be noted that the parameter d (i) in the formula (1) includes the blowing temperature (i), the cold wind butterfly valve opening (i), the blowing temperature (j), and the cold wind butterfly opening (j) in the i-th operation result data. W (i) in Equation (2) is a weight that increases as the distance d (i) decreases. In addition, the parameter p in the formula (2) represents a positive constant. Thereby, the process of step S1 is completed and a combustion control process progresses to the process of step S2.

  In the process of step S2, the dome temperature target value setting unit 104b sets the current blast temperature (j) and the cold air butterfly valve opening (j) in the model constructed by the process of step S1, thereby setting the dome temperature target value. (J) is calculated. Specifically, by using the model constructed by the process of step S1, the relationship between the index of the heat level of the hot stove, the index of the thermal margin of the hot stove, and the index of the load of the hot stove is as shown in FIG. Can be visualized. FIG. 7 shows the dome temperature on the horizontal axis and the blast temperature on the vertical axis, and the cold air butterfly valve opening is indicated by contour lines. The cold air butterfly valve opening was calculated with a model constructed while changing the dome temperature and the air blowing temperature at appropriate intervals, and the contours were displayed. The area surrounded by the thin line is a portion where the operation result data exists, and the other area is an extrapolation area, and the contour line is not displayed because the reliability of the model is lowered.

  In the above region, a region A sandwiched between bold lines is a region where the cold-air butterfly valve opening degree of the succeeding furnace at the hot-air furnace switching time is 40 to 60%, and an appropriate level is achieved. For example, when it is desired to set the cold air butterfly valve opening to 50% when the target air temperature is 1140 ° C., the line of the air temperature 1140 ° C. is traced to the right as shown in FIG. 8, and the cold air butterfly valve opening is 50%. It can be seen that the dome temperature target value may be set to 1100 ° C. by following down from the intersection P with the contour line. On the other hand, a region B in FIG. 7 is a region where the heat level is high despite the high load of the hot stove and is safe in operation, but the region where the heat level can be lowered to an appropriate level. . Therefore, when it is determined that the current operation state is in the regions B and C, the dome temperature target value may be set so that the dome temperature enters the region A. Thereby, the process of step S2 is completed and a combustion control process progresses to the process of step S3.

  In the process of step S3, the input heat amount setting unit 104c calculates a set value of the input heat quantity so as to asymptotically achieve the dome temperature target value set by the process of step S2, and the calculated set value of the input heat quantity The flow rate of the combustion gas input in the combustion period is controlled via the gas flow rate control unit 105 so that In this embodiment, the input heat amount is controlled by adjusting the flow rate of the combustion gas. However, the input heat amount may be controlled by adjusting the calories of the combustion gas. Thereby, the process of step S3 is completed and a series of combustion control processes are complete | finished.

[Modification]
In the above embodiment, a local average model is used as a model to be constructed, but a linear regression model or a local linear regression model can also be used. In either case, the model formula is as shown in the following formula (4). The coefficients a, b, and c in the formula (4) are constants, and a set of the blowing temperature (i), the cold air butterfly valve opening degree (i), and the dome temperature (i) extracted for each hot stove. It can be obtained as a set of coefficients a, b, c that minimizes the following formula (5).

  However, in the case of the local linear regression model, the formula (5) is expressed as the following formula (6) using the weight W (i) shown in the formula (2), and the current blowing temperature (j) The regression is performed by weighting the data similar to the dome temperature (j) more heavily. That is, in the case of the local linear regression model, constants a, b, and c are obtained each time for the current values of the blowing temperature (j) and the dome temperature (j).

  As described above, in the local average model and the local linear regression model, instead of determining one model coefficient and using it in the entire region, the model is used each time for the current air temperature and the cold butterfly valve opening. Ask. For this reason, it is possible to cope with the case where the input / output characteristics of the model are nonlinear or fluctuate with time, and the model accuracy can be improved, so that the model is suitable. In addition, you may deform | transform the said Numerical formula (4) into the form which outputs dome temperature (j) directly like Numerical formula (7) shown below.

  As is clear from the above description, in the combustion control processing of the hot stove that is an embodiment of the present invention, the combustion control device 104 includes an index indicating the heat level in the blowing period of each hot stove and the heat of each hot stove. Using the data of the index representing the load and the index representing the thermal margin of each hot stove, a model representing the relationship between these indices is constructed for each hot stove, and the index representing the thermal load and the thermal margin are calculated. The target index value is set for each hot stove, and the set value is input to the model of each hot stove to calculate the target value of the heat level of each hot stove. The amount of heat input to the heat storage section of each hot stove is controlled so as to asymptotically match. Thereby, when the load of a hot stove fluctuates, it can suppress that thermal efficiency falls.

  Although the embodiment to which the invention made by the present inventor is applied has been described above, the present invention is not limited by the description and the drawings that form a part of the disclosure of the present invention according to this embodiment. For example, each index of the load of the hot stove, the heat level, and the heat margin is not limited to one, and a plurality of indices may be used. Specifically, the blast temperature and flow rate are used as indicators of the load of the hot stove, the dome temperature and the quartz brick joint temperature are used as indicators of the heat level, and the cold butterfly valve opening and the mixed cold air amount are used as indicators of the heat margin, respectively. You can also.

  In this case, data on air temperature (i), air flow (i), cold butterfly valve opening (i), mixed cold air volume (i), dome temperature (i), and quartz brick seam temperature (i) are collected. , The air temperature (i), the flow rate (i), the dome temperature (i), the dome temperature (i), and the quartz brick seam temperature (i) in the data, and the cold air butterfly valve in the data according to the current distance between these values A local average model that takes a weighted average of the opening degree and the amount of mixed cold air may be used, or a linear regression model or a local linear regression model may be used. As described above, other embodiments, examples, operational techniques, and the like made by those skilled in the art based on the present embodiment are all included in the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Hot blast furnace supply system 10 Hot blast furnace 11 Combustion chamber 12 Thermal storage chamber 13 Fuel gas supply port 14 Combustion air supply port 15 Dome part 16 Quartz brick 16a Quartz brick lower part 17 Cold wind supply port 20 Blast furnace 21 Mixed-cooled butterfly valve 22 Cold wind butterfly valve 23 Blow temperature measurement unit 24 Blow temperature control unit 100 Combustion control system 101 Dome temperature measurement unit 102 Cold air butterfly valve opening measurement unit 103 Operation result database 104 Combustion control device 104a Model construction unit 104b Dome temperature target value setting unit 104c Input heat amount setting Part 105 Combustion gas flow rate adjustment part

Claims (3)

In multiple hot-air furnaces, the combustion period in which the heat storage section in the furnace is heated with combustion gas to accumulate thermal energy and the blowing period in which hot air is generated by heat exchange with the heat storage section through cold air in the furnace are repeatedly executed A hot air furnace combustion control method for supplying hot air to a blast furnace by
Using the data of the index that represents the heat level of each hot stove during the blowing period, the index that represents the thermal load of each hot stove, and the index that represents the thermal margin of each hot stove, the relationship that holds between these indices Building a model for each hot stove,
Set the value of the index representing the thermal load and the index representing the thermal margin for each hot stove, and input the set value to the model of each hot stove to calculate the target value of the heat level of each hot stove Steps,
Controlling the amount of heat input to the heat storage section of each hot stove so that the heat level of each hot stove asymptotically matches the target value;
A method for controlling combustion of a hot stove.   The index representing the heat level is the dome temperature at the end of the blowing period of each hot stove, the index representing the thermal load is the temperature of hot air blown to the blast furnace, and the index representing the heat margin is the blowing of each hot stove. The combustion control method for a hot stove according to claim 1, wherein the opening degree of the cool air butterfly valve of the follower of each hot stove at the end of the period. In multiple hot-air furnaces, the combustion period in which the heat storage section in the furnace is heated with combustion gas to accumulate thermal energy and the blowing period in which hot air is generated by heat exchange with the heat storage section through cold air in the furnace are repeatedly executed A hot air furnace combustion control device for supplying hot air to a blast furnace,
Using the data of the index that represents the heat level of each hot stove during the blowing period, the index that represents the thermal load of each hot stove, and the index that represents the thermal margin of each hot stove, the relationship that holds between these indices A model building unit that builds a model to represent for each hot stove;
Set the value of the index representing the thermal load and the index representing the thermal margin for each hot stove, and input the set value to the model of each hot stove to calculate the target value of the heat level of each hot stove A target value setting unit;
An input heat amount setting unit that controls the input heat amount to the heat storage unit of each hot stove so that the heat level of each hot stove asymptotically matches the target value;
A combustion control apparatus for a hot stove, comprising:

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