Monitoring device and monitoring method for nozzle clogging conditions and method for manufacturing steel

Abstract

A nozzle clogging monitoring device, a monitoring method, and a method for manufacturing a spray nozzle. A nozzle clogging monitoring device comprising: an acquisition unit (160) for acquiring a first value, which is the value of a flow meter installed in a pipe attached to a manufacturing facility having a spray nozzle, and a second value, which is the value of at least one of a pressure gauge and a valve opening, as the latest data; a setting unit (162) for setting a threshold value of the second value relative to the first value over time from past data of the first value and the second value; and a determination unit (163) for determining that nozzle clogging has occurred when the latest data falls outside the range of the threshold value.

Description

Technology Field

[0001] The present invention relates to a monitoring device and monitoring method for nozzle clogging conditions and a method for manufacturing steel. Background Technology

[0002] In the continuous casting of steel using a continuous casting machine, cooling water is sprayed onto the cast slab from a spray nozzle (nozzle) to cool the slab (secondary cooling). In such equipment, a pressure gauge is installed in the piping to monitor for clogging of the spray nozzle, and if the pressure value relative to the standard flow rate exceeds a preset threshold, it is determined to be abnormal.

[0003] Patent Document 1 describes a secondary cooling method for continuous casting in which cooling water is supplied to the circumference of a cast slab while monitoring whether the supply pressure and / or flow rate per unit time of cooling water supplied from a nozzle falls within a constant width range following the supply pressure-flow rate curve of the nozzle.

[0004] In addition, Patent Document 2 describes a method for determining that there is a problem with the nozzle by calculating the difference between the measured values ​​of the back pressure of the spray nozzle and the valve opening of the flow control valve and each reference pattern, and when either or both of the difference between the average value of the back pressure difference and the average value of the valve opening difference become greater than or equal to a predetermined value. Prior art literature

[0005] Japanese Published Patent Application No. 2001-179141, Japanese Patent Application No. 3373007 The problem to be solved

[0006] However, since the methods described in Patent Documents 1 and 2 continue monitoring based on preset threshold values, there are cases where the quantity or back pressure values ​​change due to individual variations of the replaced parts after parts are replaced due to trouble or lifespan. In such cases, even though there are no operational abnormalities in the new parts, the data is judged to be abnormal, and there were many instances where the original purpose of blockage monitoring could not be performed. Since the line had to be stopped and verification work performed every time an abnormality was detected, operational efficiency was significantly reduced due to over-detection of abnormalities. On the other hand, if the pressure after replacement is lower than the model originally intended, even if pressure blockage occurs compared to the conventional method, it is not judged to be abnormal unless the blockage progresses, which has become a major problem.

[0007] Therefore, the present invention, having been made with attention to the above problem, aims to provide a nozzle clogging condition monitoring device and monitoring method capable of accurately detecting the occurrence of clogging in a spray nozzle of a continuous casting machine, and a method for manufacturing steel. means of solving the problem

[0008] (1) According to one embodiment of the present invention, a nozzle blockage monitoring device is provided, comprising: a first value which is the value of a flow meter installed in a pipe attached to a manufacturing facility having a spray nozzle, and a second value which is the value of at least one of a pressure gauge and a valve opening, as the latest data; a setting unit which sets a threshold value of the second value relative to the first value over time from past data of the first value and the second value; and a determination unit which determines that nozzle blockage has occurred when the latest data is outside the range of the threshold value.

[0009] (2) In the nozzle clogging condition monitoring device described in (1) above, the setting unit sets the threshold value from the previous past data when the amount of change in the previous past data is less than or equal to a predetermined value.

[0010] (3) According to one aspect of the present invention, a method for monitoring a nozzle blockage situation is provided, comprising: a first value, which is the value of a flow meter installed in a pipe attached to a manufacturing facility having a spray nozzle, and a second value, which is the value of at least one of a pressure gauge and a valve opening, as the latest data; a setting process for setting a threshold value of the second value relative to the first value over time from past data of the first value and the second value; and a determination process for determining that nozzle blockage has occurred when the latest data is outside the range of the threshold value.

[0011] (4) According to one embodiment of the present invention, a method for manufacturing steel is provided in which steel is continuously cast using a continuous casting machine, and when the continuous casting is performed, the nozzle clogging of the spray nozzle of the continuous casting machine is monitored using the nozzle clogging condition monitoring method described in (3) above. Effects of the invention

[0012] According to one aspect of the present invention, a nozzle clogging condition monitoring device and monitoring method, and a method for manufacturing steel are provided, which can accurately detect the occurrence of clogging in a spray nozzle of a continuous casting machine. Brief explanation of the drawing

[0013] FIG. 1 is an explanatory diagram showing a continuous casting machine related to one embodiment of the present invention. Figure 2 is a schematic diagram showing a secondary cooling zone. Figure 3 is a schematic diagram showing the relationship between the model and the upper and lower limits. Figure 4 is a graph illustrating standardization in change pattern 2. Figure 5 is a graph showing the relationship between the flow rate and back pressure (spray back pressure) before and after equipment replacement in an embodiment. Figure 6 is a graph showing the relationship between the flow rate and the valve opening before and after equipment replacement in an embodiment. FIG. 7 is a graph showing the detection and occurrence of nozzle clogging in the embodiment. Specific details for implementing the invention

[0014] In the following detailed description, embodiments of the present invention are described with reference to the drawings. In the description of the drawings, identical or similar parts are given identical or similar reference numerals, and redundant descriptions are omitted. Each drawing is schematic and may differ from reality. Furthermore, the embodiments described below are intended to illustrate devices or methods for embodying the technical concept of the present invention, and the technical concept of the present invention is not limited to the materials, structures, arrangements, etc., of the constituent parts as described below. The technical concept of the present invention may be subject to various modifications within the technical scope defined by the claims described in the patent claims.

[0015] Monitoring device for continuous casting machine and nozzle clogging conditions

[0016] As shown in FIG. 1, a nozzle clogging monitoring device (16) related to the present embodiment of the invention is installed in a continuous casting machine (1). The continuous casting machine (1) manufactures a cast slab (3) by continuously casting steel. In addition, the type of the continuous casting machine (1), such as a curved bend type or a vertical bend type, is not particularly limited. Also, in the present embodiment, the continuous casting machine (1) manufactures a slab as a cast slab (3), which is a rectangular cast slab with a cross-sectional shape that is orthogonal to the longitudinal direction.

[0017] A continuous casting machine (1) is equipped with a ladle (10), a tundish (11), a mold (12), a plurality of rolls (13), a secondary cooling zone (14), a cutting device (15), and a monitoring device (16). In such a continuous casting machine (1), molten steel (2) contained in the ladle (10) is supplied to a tundish (11), which is an intermediate vessel, and then supplied from the tundish (11) to a mold (12). The molten steel (2) supplied to the mold (12) forms a solidified shell by cooling (primary cooling) in the mold (12). Then, as this solidified shell is drawn out, a cast billet (3) is manufactured by further cooling (secondary cooling) in the secondary cooling zone (14). After that, the main plate (3) is cut to a predetermined length in a cutting device (15).

[0018] The secondary cooling zone (14) is an area that cools the cast billet (3) by spraying cooling water from a spray nozzle. The secondary cooling zone (14) is composed of multiple cooling zones, and in the example shown in FIG. 1, it is composed of three cooling zones (14a to 14c). Also, each cooling zone of the secondary cooling zone (14) is composed of multiple zones arranged in multiple directions in the casting direction and the plate width direction, and in these zones, about 20 to 60 spray nozzles are installed in each zone. Also, the casting direction is the direction in which the cast billet (3) moves within the machine of the continuous casting machine (1) (the longitudinal direction of the cast billet (3) from the mold (12) in FIG. 1 toward the cutting device (15)), and the plate width direction is the width direction of the cast billet (3) (the front-back direction in FIG. 1).

[0019] FIG. 2 is an explanatory diagram showing a secondary cooling zone (14), showing a plan view from the casting direction at a position between adjacent rolls (13) in the casting direction. As shown in FIG. 2, a plurality of spray nozzles (141) are installed in the gap between adjacent rolls (13) in the casting direction. The spray nozzles (141) are water spray nozzles or air mist spray nozzles, and spray cooling water (142) onto the casting slab (3). In addition, the cooling water (142) supplied to the spray nozzles (141) is supplied through a pipe (not shown) for each zone of the cooling zone, and the flow rate is adjusted by a flow rate control valve (not shown) installed in this pipe. In addition, the adjustment of the flow rate by the flow rate control valve is carried out by adjusting the opening (valve opening) of the flow rate control valve. In addition, each pipe is equipped with a flow meter (not shown) for measuring the flow rate of the supplied cooling water (142) and a pressure gauge (not shown) for measuring the pressure (water pressure) of the supplied cooling water (142).

[0020] The monitoring device (16) is a nozzle clogging monitoring device that monitors whether a clogging has occurred in the spray nozzle (141), and is equipped with an acquisition unit (160), a memory unit (161), a setting unit (162), and a judgment unit (163). The monitoring device (16) is configured, for example, as a computer system such as a personal computer having computational processing functions, and is equipped with ROM, RAM, CPU, etc. The monitoring device (16) realizes each of the functions of the acquisition unit (160), memory unit (161), setting unit (162), and judgment unit (163) described later in software by executing various dedicated programs stored in advance in ROM, etc.

[0021] <Monitoring Method for Nozzle Clogging>

[0022] [Acquisition Process]

[0023] A method for monitoring the nozzle blockage status of a spray nozzle (141) by a monitoring device (16) is described. In the method for monitoring the nozzle blockage status, first, the acquisition unit (160) acquires a first value (measured value of flow rate) which is the value of a flow meter installed in the piping attached to the continuous casting machine (1), and a second value which is at least one of the values ​​of a pressure gauge and valve opening installed in the piping (measured value of pressure or valve opening) (acquisition process). The first value and the second value are acquired for each zone of the cooling unit. Also, the second value may be either the value of the pressure gauge or the valve opening, but from the perspective of precision in detecting nozzle blockage, it is more preferable for it to be both values. Also, in the acquisition process, the acquired first value and the second value are stored in the memory unit (161).

[0024] In the memory unit (161), in addition to the latest data, which is the first value and second value acquired, past data, which is the first value and second value from past operations, is also stored. In the memory unit (161), at least past data from the first period described later is stored, and whenever the latest data is stored, the past data may be deleted starting from the oldest.

[0025] [Setup Process]

[0026] In addition, in the method for monitoring nozzle clogging conditions of the present embodiment, the setting unit (162) sets a threshold value for a second value relative to a first value over time from past data stored in the memory unit (161) (setting process). The threshold value is set as a lower limit value and an upper limit value that are displayed in a predetermined range for a model (relationship equation) representing the relationship between the first value and the second value. These upper limit value and lower limit value may be set as a ±5 σ value of the relationship equation (model) obtained from past data. This verification value is not limited to a ±5 σ value and can be arbitrarily set so that the case where nozzle clogging occurs can be detected as an abnormality, for example, it may be set in the range of 3 σ to 6 σ. In addition, the threshold value may be set based on actual values ​​when nozzle clogging occurs. In this case, when equipment with nozzle clogging occurs is installed—that is, when nozzle clogging does not occur in the equipment—the difference between the actual value and the actual value when nozzle clogging occurs is calculated, and the upper and lower limits, which are threshold values, are set.

[0027] In addition, when the second value includes two values ​​of pressure and valve opening, two threshold values ​​are set based on two models: a pressure model relative to flow rate and a valve opening model relative to flow rate. For example, when the threshold value is set based on a pressure model relative to flow rate in past data, as shown in FIG. 3, for a model representing the relationship between flow rate and pressure, a value of ±5 σ is set as the upper and lower threshold values, respectively. Furthermore, different threshold values ​​may be set for each zone. In this case, for example, for zones where nozzle clogging occurs frequently, it is preferable to set a threshold value based on actual values ​​when the nozzle clogging described above occurs.

[0028] In the setting process, a threshold value is set by calculating a model from past data of a predetermined period. This predetermined period is also called the first period and is set according to the usage conditions of the equipment, etc., so that the precision of the model becomes sufficient. For example, if it is a general continuous casting machine (1), the first period may be set as one week.

[0029] The setting process is carried out independently of the acquisition process. In addition, in the setting process, the threshold value is set over time. That is, the threshold value is changed over time. In addition, the change in the threshold value may be carried out under the conditions of the following change pattern 1 or change pattern 2.

[0030] (Change Pattern 1)

[0031] In the case of change pattern 1, the change of the threshold value is carried out according to the elapsed period of a second period. The second period is not particularly limited, but can be set as, for example, a period of 1 day to 1 week. For example, if the second period is 1 week, when 1 week has elapsed since the threshold value was previously set, the setting unit (162) acquires past data of the previous first period stored in the memory unit (161) and sets the threshold value from the acquired past data. Also, the past data used to set the threshold value may be based on the acquisition timing of the acquisition process, or it may be a time average of the data acquired in the acquisition process over 1 hour.

[0032] (Change Pattern 2)

[0033] In the case of change pattern 2, the change in the threshold is carried out based on the amount of change in the previous past data in addition to the passage of a second period identical to change pattern 1. That is, in change pattern 2, at each second period, whether or not to change the threshold is determined based on the amount of change in the previous past data.

[0034] The amount of variation in the previous past data is the amount of variation in the data for each third period, which is a plurality of fixed periods in the previous past data. Here, the past data used when setting the threshold value of the second value for the previous first value is called the first data, and the past data of the third period used to calculate the amount of variation is called the second data. Furthermore, the amount of variation in the data for each third period is calculated as the distance from the first data to the second data in the third period for which the amount of variation is calculated. Specifically, the distance calculated is the distance between the second data and the first data in a coordinate system represented by the first value and the second value. For example, as shown in FIG. 4, the distance is calculated using a coordinate system in which the value of the flow rate, which is the first value, is the horizontal axis and the value of the pressure (spray back pressure), which is the second value, is the vertical axis. In this case, for each data of the second data consisting of multiple data, the distance to the closest data among the first data consisting of multiple data is calculated. For example, as shown in FIG. 4, when a distance is calculated for data (t), which is one of the second data, the distance (d) between the closest data (s) among the first data and data (t) is calculated. Then, distance calculations are performed for all data constituting the second data, and an average value is calculated for each calculated distance. Then, the standard deviation σ of the average value of the distance calculated for each of the multiple third periods is calculated as a variation amount. After that, it is determined whether each of the average values ​​of the multiple third periods falls within the range of “the average value of the entire multiple third period ± 2 σ”, preferably within the range of “the average value of the entire multiple third period ± 1 σ”. As a result of the determination, if all are within the range, the threshold value is updated, otherwise, the threshold value is kept as is.

[0035] As an example, the third period can be set to one day by using past data from the previous 1 to 2 consecutive weeks prior as the previous past data. In this case, the change of the threshold value is determined by determining whether the standard deviation of the average value of the distance of the data for each day of the previous 1 to 2 consecutive weeks over the 1 to 2 weeks is less than or equal to a predetermined value.

[0036] [Judgment Process]

[0037] After the acquisition process, the judgment unit (163) determines that nozzle clogging has occurred in the spray nozzle (141) of the determined zone if the latest data acquired in the acquisition process falls outside the range of the newest threshold value set in the setting process. In addition, if the latest data falls within the range of the threshold value, it is determined that nozzle clogging has not occurred. If it is determined that nozzle clogging has occurred, the operator is notified of the occurrence of nozzle clogging, and, if necessary, measures such as inspection are taken.

[0038] In the method for monitoring nozzle clogging conditions related to the present embodiment, the acquisition process is repeated at predetermined time intervals, and the judgment process is repeated at the same frequency as the acquisition process or at a lower frequency than the acquisition process, so that the nozzle clogging condition is continuously monitored while continuous casting is performed.

[0039] Here, during the operation of the continuous casting machine (1), the nozzle hole of the spray nozzle (141) becomes clogged due to the accumulation of scale, etc. The ease of clogging of this nozzle hole varies depending on the location of the equipment, and cleaning is performed about once every 1 to 6 months depending on the occurrence of clogging. Since cleaning takes about 1 to 3 hours depending on the location, it is difficult to increase the cleaning frequency. Also, due to the difference in parts between the new parts before and after replacement, the amount of coolant and back pressure after replacement may change significantly from the amount of coolant and back pressure before replacement. However, according to this embodiment, the amount of coolant and back pressure of each zone after parts replacement are monitored for a certain period of time, and the critical value is changed at a stable stage, so the influence of the change in value at the time of parts replacement can be eliminated. For this reason, the occurrence of clogging in the spray nozzle (141) of the continuous casting machine (1) can be detected with high precision.

[0040] <Example of Variation>

[0041] Although the present invention has been described above with reference to specific embodiments, it is not intended to limit the invention by such description. By referring to the description of the present invention, it is obvious to those skilled in the art that other embodiments of the present invention, including various variations in addition to the disclosed embodiments, are also apparent. Accordingly, it should be understood that the embodiments of the invention described in the claims encompass embodiments that include the variations described herein, either alone or in combination.

[0042] For example, in the above embodiment, it was stated that a slab is manufactured as a cast billet (3) in the continuous casting machine (1), but the present invention is not limited to such examples. For example, in the continuous casting machine (1), a cast billet of a different cross-sectional shape, such as a bloom or a billet, may be manufactured.

[0043] Also, when the continuous casting machine (1) manufactures slabs of various widths, the model or threshold value may be set multiple times depending on the width of the slab.

[0044] In addition, in the above embodiments, a continuous casting machine was described as an example of a manufacturing facility to which the present invention is applied, but the present invention is not limited to such examples. Any facility to which the present invention is applicable may be a manufacturing facility having a spray nozzle, and may be, for example, other manufacturing facilities such as a steel rolling facility.

[0045] Examples

[0046] The inventors will now describe an embodiment they carried out. In the embodiment, as in the above embodiment, when continuously casting steel with a continuous casting machine (1), monitoring of the nozzle blockage situation was performed using a monitoring device (16). Then, the number of cases where nozzle blockage was detected and the number of cases where nozzle blockage actually occurred as an abnormality were investigated.

[0047] In the example, as a setting process, a model was calculated from past data, and the value of ±5 σ of the model was set as the upper and lower limits as threshold values. At this time, the first period for calculating the threshold values ​​was set to two weeks. Also, in the setting process, when changing the threshold values, the conditions of change pattern 3 of the above example were used. Specifically, the threshold values ​​were changed when the daily average fluctuation amount of past data during the preceding two-week period was -5% or more and 5% or less. Also, the first and second periods were set to two weeks. In addition, in the example, two values, back pressure and valve opening, were used as the second values, and in the judgment process, it was determined that nozzle clogging had occurred when either value exceeded the range of the threshold values.

[0048] Figures 5 and 6 respectively show the relationship between the flow rate (first value), back pressure, and valve opening (second value) before and after equipment replacement. Figures 5 and 6 show the data (first value and second value) before and after equipment replacement and the threshold values ​​based on these data. In addition, Figures 5 and 6 show the data before equipment replacement as model data and the data after equipment replacement as data at the time of equipment replacement, respectively. As shown in Figures 5 and 6, it was confirmed that the model, which is the relationship between the first value and the second value, changes due to equipment replacement. Furthermore, it was confirmed that at the threshold values ​​before equipment replacement, an abnormality is detected even in equipment after equipment replacement, that is, in a state where nozzle clogging has not occurred.

[0049] Figure 7 shows the number of nozzle blockage detections, the number of nozzle blockage occurrences, and the true detection rate during periods A and B. The true detection rate is the ratio of actual nozzle blockage occurrences among the detected nozzle blockages. Additionally, period A is a period in which the nozzle blockage situation was monitored using a conventional method, and a threshold value was set based on the performance of the equipment initially installed. Additionally, period B is a period in which the nozzle blockage situation monitoring method related to the above embodiment was used, and the threshold value was changed over time. Additionally, period A was for 8 months, and period B was for 7 months. As shown in Figure 7, by changing the threshold value over time, it was confirmed that the true detection rate was significantly improved from 33% to 75%, and over-detection was reduced. Explanation of the symbols

[0050] 1 : Continuous casting machine 10 : Raid 11 : Turnish 12 : Mold 13 : LoL 14: Secondary cooling zone 141 : Spray nozzle 142 : Coolant 15: Cutting device 16 : Monitoring device 160 : Acquisition Department 161 : Memory 162 : Settings section 163 : Judgment Division 2 : Molten Steel 3 : Main Section

Claims

Claim 1 A nozzle clogging monitoring device comprising: an acquisition unit that acquires as latest data a first value, which is the value of a flow meter installed in piping attached to a manufacturing facility having a spray nozzle, and a second value, which is at least one of a pressure gauge and a valve opening; a setting unit that sets a threshold value for the second value relative to the first value over time from past data of the first value and the second value; and a determination unit that determines that nozzle clogging has occurred when the latest data falls outside the range of the threshold value. Claim 2 A monitoring device for nozzle clogging conditions according to claim 1, wherein the setting unit sets the threshold value from the previous past data when the amount of change in the previous past data becomes less than or equal to a predetermined value. Claim 3 A method for monitoring a nozzle blockage situation, comprising: an acquisition process for acquiring a first value, which is the value of a flow meter installed in piping attached to a manufacturing facility having a spray nozzle, and a second value, which is at least one of a pressure gauge and a valve opening, as the latest data; a setting process for setting a threshold value of the second value relative to the first value over time from past data of the first value and the second value; and a determination process for determining that nozzle blockage has occurred when the latest data falls outside the range of the threshold value. Claim 4 A method for manufacturing steel, wherein steel is continuously cast using a continuous casting machine, wherein, when performing continuous casting, the nozzle clogging of the spray nozzle of the continuous casting machine is monitored using the nozzle clogging condition monitoring method described in claim 3.

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