Anti-blocking flushing method for continuous casting secondary cooling water nozzle

Abstract

The application discloses a kind of continuous casting secondary cooling water nozzle anti-blocking flushing method.The method includes: periodically sampling the water pressure and water flow data of the secondary cooling water unit;Every time the tail of the casting blank passes through a secondary cooling partition, the nozzle flushing process of the current secondary cooling partition is started, which includes: according to the water pressure and water flow sampling record, it is judged whether the nozzle in the current secondary cooling partition is blocked, if not, the standard flushing water volume is used as the target flushing water volume, otherwise, the strong flushing water volume is used as the target flushing water volume;When the tail of the casting blank is away from the end of the current secondary cooling partition, the valve device of the current secondary cooling water unit is opened, and the nozzle in the current secondary cooling partition is flushed according to the target flushing water volume.In the method of the application, the nozzle in the secondary cooling area is flushed during the process of the tail of the casting blank gradually leaving the secondary cooling area, thereby effectively preventing nozzle blockage.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of continuous casting machine secondary cooling water nozzle anti-blocking technology, more particularly to a kind of continuous casting secondary cooling water nozzle anti-blocking flushing method. BACKGROUND

[0002] In modern steel production process, continuous casting is a very important process. So-called continuous casting is to continuously cast molten steel into billet (slab, round billet, etc.), and the equipment for completing this process is called continuous casting machine.

[0003] Taking slab continuous casting machine as an example, the continuous casting machine includes a crystallizer and a plurality of fan-shaped segments with roller beds, the crystallizer is arranged on a relatively high platform, and the plurality of fan-shaped segments are arranged in combination below the crystallizer. A pipe system for providing secondary cooling water spraying (relative to the crystallizer cooling, it belongs to secondary cooling) is also arranged on the fan-shaped segment, so the fan-shaped segment area is also called secondary cooling area. During continuous casting, molten steel is first cast into the crystallizer, and the molten steel in the crystallizer is solidified into an initial billet configuration by the crystallizer cooling. After the initial billet leaves the crystallizer, it slowly moves along the roller bed in the fan-shaped segment until it leaves the last fan-shaped segment. The billet receives the spraying cooling of the secondary cooling water in the fan-shaped segment area, i.e. the secondary cooling area, to rapidly cool and solidify the billet.

[0004] The pipe system for providing secondary cooling water spraying on the fan-shaped segment is called secondary cooling water system, which usually consists of pressure pump equipment, water pipe, a series of valve devices and numerous nozzles, etc. The nozzles are discretely distributed in the secondary cooling area (in the fan-shaped segment) through which the billet passes, and the nozzles face the path through which the billet passes. The nozzles are connected to the pressure pump equipment through the water pipe, and the valve devices are installed in the water pipe, which are controlled to be connected to the production control computer. The production control computer can control the water flow of the nozzles by controlling the opening degree of the valve devices. During continuous casting, when the billet passes through the secondary cooling area, the water pipe is pressurized by the pressure pump equipment, and the production control computer controls the valve devices to control the water flow from the water pipe into the nozzles. Under the water pressure provided by the pressure pump equipment, the secondary cooling water is sprayed from the nozzles to form spraying cooling on the billet.

[0005] The secondary cooling region is usually divided into multiple secondary cooling sub-zones (for the purpose of forming a gradient cooling for the casting blank), and correspondingly, the secondary cooling water system is also provided with multiple secondary cooling water units, the number of the secondary cooling water units is consistent with the number of the secondary cooling sub-zones, and one secondary cooling water unit corresponds to one secondary cooling sub-zone. Each secondary cooling water unit includes an independent water passage and a valve device, the nozzles arranged in the secondary cooling sub-zone are communicated with the water passage of the secondary cooling water unit corresponding to the secondary cooling sub-zone, each secondary cooling sub-zone is provided with secondary cooling water spray by the secondary cooling water unit corresponding to the secondary cooling sub-zone, and each secondary cooling water unit can independently control the secondary cooling water spray of the secondary cooling sub-zone. The secondary cooling water system includes a system main pipe communicated with a pressure pump device. Each secondary cooling water unit includes a unit main pipe communicated with the system main pipe, and the nozzles arranged in the secondary cooling sub-zone corresponding to the secondary cooling water unit are communicated with the unit main pipe through the water passage. The unit main pipe of each secondary cooling water unit is provided with a pressure detector and a flow detector, and the pressure detector and the flow detector are signal-connected with a production control computer. The production control computer can obtain the cooling water pressure and flow data in the unit main pipe through the pressure detector and the flow detector.

[0006] Due to the harsh environment in the secondary cooling region, the nozzles in the secondary cooling region are often blocked due to various reasons, which is very unfavorable for continuous casting production, especially when casting some special steel, the water flow of the nozzle is small, which further aggravates the nozzle blockage. At present, the main methods to solve the nozzle blockage problem are: through the optimization design of the nozzle or the water supply structure to realize the nozzle cleaning to prevent the nozzle from being blocked; or manually replace the blocked nozzle with a new nozzle. However, the current methods cannot predict the nozzle blockage, and the efficiency of handling the nozzle blockage is not high and the effect is not good.

[0007] Chinese patent (CN106670447A) discloses a continuous casting secondary cooling water nozzle system and a control method thereof. The continuous casting secondary cooling water nozzle system and the control method thereof can select a larger nozzle. Since the effective aperture of the nozzle is larger, the particles of the blockage allowed to pass through are also larger, thereby reducing the blockage probability of the nozzle and reducing the casting blank quality problem caused by the nozzle blockage. However, in the technical solution of the patent, only the structure optimization of the nozzle is involved, and the nozzle blockage is not predicted, and the pertinence of preventing the nozzle blockage is not strong. SUMMARY

[0008] The present application aims to provide a method for preventing the clogging of the water nozzle of the secondary cooling system of a continuous casting machine, in which the water nozzle is flushed with water during the process of the tail of the cast slab gradually leaving the secondary cooling zone, thereby effectively preventing the clogging of the water nozzle.

[0009] In order to achieve the above technical purpose, the present application adopts the following technical solution:

[0010] A method for preventing the clogging of the water nozzle of the secondary cooling system of a continuous casting machine, for each secondary cooling zone in the secondary cooling zone, a set of flushing control parameters is set in advance, the parameters in the flushing control parameters include: the distance D of the tail of the cast slab leaving, the standard flushing water volume F0, the standard flushing time T0, the strong flushing water volume F1 and the strong flushing time T1.

[0011] The method for preventing the clogging of the water nozzle of the secondary cooling system of a continuous casting machine includes the following steps:

[0012] Step 1, the continuous casting machine casts the cast slab, during the casting process of the continuous casting machine, for each secondary cooling water unit in the secondary cooling water system, the water pressure and water flow data of the secondary cooling water unit are periodically sampled according to the preset sampling period, and the water pressure p and water flow f data sampled in each sampling period are combined to form a water pressure and water flow sampling record;

[0013] Step 2, after the continuous casting machine finishes casting and enters the drawing program, the tail of the cast slab enters the secondary cooling zone, in the secondary cooling zone, whenever the tail of the cast slab passes through a secondary cooling zone, the secondary cooling zone is taken as the current secondary cooling zone, the secondary cooling water unit corresponding to the current secondary cooling zone is taken as the current secondary cooling water unit, and the flushing control parameter corresponding to the current secondary cooling zone is taken as the current flushing control parameter, and then the nozzle flushing process of the current secondary cooling zone is started.

[0014] Further, the nozzle flushing process in step 2 includes:

[0015] Step 2.1, according to the water pressure and water flow sampling record of the current secondary cooling water unit, it is judged whether the nozzle in the current secondary cooling zone is clogged or not;

[0016] Step 2.2, if it is determined that the nozzle in the current secondary cooling zone is not clogged, then: the standard flushing water volume F0 in the current flushing control parameter is taken as the target flushing water volume, and the standard flushing time T0 in the current flushing control parameter is taken as the target flushing time;

[0017] If it is determined that the nozzle in the current secondary cooling zone is clogged, then: the strong flushing water volume F1 in the current flushing control parameter is taken as the target flushing water volume, and the strong flushing time T1 in the current flushing control parameter is taken as the target flushing time;

[0018] Step 2.3, when the distance between the slab tail and the end of the current secondary cooling zone reaches the slab tail leaving distance D in the current flushing control parameter, set the secondary cooling water flow of the current secondary cooling water unit to the target flushing water amount, open the valve device of the current secondary cooling water unit, and flush the nozzles in the current secondary cooling zone;

[0019] Step 2.4, time the nozzle flushing process, and when the nozzle flushing time reaches the target flushing time, close the valve device of the current secondary cooling water unit.

[0020] Further, the parameters included in the flushing control parameter also include a water amount deviation judgment threshold E0 and a water amount fluctuation judgment threshold σ0; for each secondary cooling water unit in the secondary cooling water system, a water pressure-water flow relationship model formula is pre-set;

[0021] The step 2.1 includes the following steps:

[0022] Step 2.1.1, for the current secondary cooling water unit, for each water pressure-water flow sampling record obtained by sampling, calculate the water flow deviation value ΔF, which includes:

[0023] According to the water pressure data p in the water pressure-water flow sampling record and according to the water pressure-water flow relationship model formula corresponding to the current secondary cooling water unit, the water flow theoretical value F corresponding to the water pressure data is calculated; the water pressure-water flow relationship model formula is:

[0024]

[0025] The water pressure-water flow relationship model formula is a sample regression model formula, in which F is the water flow theoretical value, a0, a1, a2, and a3 are regression coefficients obtained when the water pressure-water flow relationship model formula is constructed by sample regression, a0 is the first regression coefficient, a1 is the second regression coefficient, a2 is the third regression coefficient, a3 is the fourth regression coefficient, p is the water pressure data in the water pressure-water flow sampling record, is the average value of the water pressure data in the regression sample data used when the water pressure-water flow relationship model formula is constructed by sample regression;

[0026] Subtract the calculated water flow theoretical value F from the water flow f in the water pressure-water flow sampling record, ΔF=F-f, to obtain the water flow deviation value ΔF;

[0027] Step 2.1.2, for the current secondary cooling water unit, calculate the average value E(ΔF) of all ΔF and the standard deviation σ(ΔF) of all ΔF;

[0028] Step 2.1.3, comparing the average value E(ΔF) of the ΔF with the water amount deviation determination threshold value E0 in the current flushing control parameter, comparing the standard deviation σ(ΔF) of the ΔF with the water amount fluctuation determination threshold value σ0 in the current flushing control parameter, if E(ΔF) < E0 and σ(ΔF) < σ0, determining that the nozzles in the current secondary cooling subzone are not blocked;

[0029] If E(ΔF) ≥ E0 or σ(ΔF) ≥ σ0, it is determined that the nozzles in the current secondary cooling subzone are blocked.

[0030] Further, the sampling period is in the range of 1-10 seconds.

[0031] Further, the sampling period is set to 5 seconds.

[0032] Further, the step 1 further comprises: if the sampled water pressure data is out of the pre-set sampling water pressure range, the water pressure and water flow sampling record to which the water pressure data belongs is cleared.

[0033] Further, the step 2.2 further comprises: saving the water pressure and water flow sampling record of the current secondary cooling subzone and the determined nozzle blockage condition information to the pre-set data storage space.

[0034] In the nozzle anti-blocking flushing method of the present application, when the tail of the cast blank leaves each secondary cooling subzone, the valve device of the secondary cooling water unit corresponding to the secondary cooling subzone is opened to flush the nozzles with water, so as to prevent the nozzles from being blocked. In the specific control process, before flushing the nozzles with water, the actual blocking condition of the nozzles is determined by model calculation, if it is determined that the nozzles are not blocked, the nozzles are flushed with standard flushing water amount and standard flushing time, which can not only prevent the nozzles from being blocked, but also avoid wasting cooling water; if it is determined that the nozzles are blocked, the nozzles are flushed with strong flushing water amount and strong flushing time, so as to actively remove the blocking objects and avoid the nozzles from being further blocked.

[0035] The nozzle anti-blocking flushing method of the present application has the beneficial effects that, in the process of the tail of the cast blank gradually leaving the secondary cooling region, the nozzles are flushed with water to prevent the nozzles from being blocked, which improves the cooling water spraying effect of the secondary cooling region and further improves the quality of the cast blank cast by the continuous casting machine. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 The flow chart of the continuous casting secondary cooling water nozzle anti-blocking flushing method of the present application. DETAILED DESCRIPTION

[0037] The application will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0038] Before describing the specific embodiments, the following matters are explained in advance:

[0039] The continuous casting length herein refers to the length along the moving path of the casting blank in the continuous casting machine with the upper opening of the crystallizer as the zero point;

[0040] The drawing process herein is a professional term in the field of continuous casting, which means the process of gradually moving the tail of the casting blank away from the continuous casting machine after the continuous casting machine finishes casting.

[0041] Referring to Figure 1 The embodiment provides a nozzle anti-blocking flushing method for continuous casting secondary cooling, which can effectively prevent nozzle blocking in the secondary cooling area, thereby improving the cooling water spraying effect and further improving the quality of the casting blank cast by the continuous casting machine.

[0042] The nozzle anti-blocking flushing method of the embodiment specifically comprises the following steps: in the production control computer, a set of flushing control parameters are set for each secondary cooling subzone in the secondary cooling area, and the flushing control parameters comprise the following parameters: the tail of the casting blank moving distance D, the water quantity deviation judgment threshold E0, the water quantity fluctuation judgment threshold σ0, the standard flushing water quantity F0, the standard flushing time T0, the strong flushing water quantity F1 and the strong flushing time T1. A water pressure and water flow relationship model formula is set in advance for each secondary cooling water unit in the secondary cooling water system.

[0043] The nozzle anti-blocking flushing method of the embodiment comprises the following steps:

[0044] Step 1, the continuous casting machine normally casts the casting blank, and in the process of casting the casting blank by the continuous casting machine, the production control computer on site periodically samples the water pressure and water flow data of each secondary cooling water unit in the secondary cooling water system according to a preset sampling period, and the water pressure p and water flow f data sampled in each sampling period are combined into a water pressure and water flow sampling record. The sampling data of the water pressure and water flow of the secondary cooling water unit are obtained by the production control computer through the pressure detector and the flow detector arranged on the unit main pipe of the secondary cooling water unit.

[0045] In the embodiment, the sampling period is usually set to 5 seconds, and in other embodiments, the sampling period can be in the range of 1-10 seconds.

[0046] Preferably, a sampling water pressure range is preset in the production control computer; if the sampled water pressure data exceeds the sampling water pressure range, it is considered that the water pressure data is abnormal data disturbed by noise signals, and the water pressure and flow sampling record to which the water pressure data belongs is cleared, so as to avoid abnormal data interference and ensure the reliability of the data in the water pressure and flow sampling record. The sampling water pressure range can be determined according to the effect of the method, and in the embodiment, the sampling water pressure range is set to [0.05, 0.25] Mpa.

[0047] Step 2: After the continuous casting machine finishes casting and enters the drawing process, the tail of the casting blank enters the secondary cooling area, and the tail of the casting blank sequentially passes through each secondary cooling subzone of the secondary cooling area until the tail of the casting blank leaves the secondary cooling area; in the secondary cooling area, when the tail of the casting blank passes through a secondary cooling subzone, i.e., the continuous casting length position of the tail of the casting blank exceeds the continuous casting length position of the end of the secondary cooling subzone, the secondary cooling subzone is taken as a current secondary cooling subzone, the secondary cooling water unit corresponding to the current secondary cooling subzone is taken as a current secondary cooling water unit, and the flushing control parameter corresponding to the current secondary cooling subzone is taken as a current flushing control parameter, and then the production control computer starts the nozzle flushing process for the current secondary cooling subzone.

[0048] The nozzle flushing process includes the following steps 2.1 to 2.4:

[0049] Step 2.1: According to the water pressure and flow sampling record of the current secondary cooling water unit, and specifically according to the matching condition between the water pressure data and the water flow data in the water pressure and flow sampling record, it is determined whether the nozzles in the current secondary cooling subzone are blocked.

[0050] Specifically, the step 2.1 includes the following steps 2.1.1 to 2.1.3:

[0051] Step 2.1.1: For each water pressure and flow sampling record sampled, the water flow deviation value ΔF is calculated, which is the difference between the water flow theoretically matched with the actual sampling water pressure data in the water pressure and flow sampling record and the actual sampling water flow data in the water pressure and flow sampling record.

[0052] Specifically, the calculation process of the water flow deviation value ΔF includes:

[0053] According to the water pressure data in the water pressure and flow sampling record, and according to the water pressure and flow relationship model formula corresponding to the current secondary cooling water unit, the water flow theoretical value F corresponding to the water pressure data is calculated; the water pressure and flow relationship model formula is:

[0054]

[0055] The water pressure-water flow rate relationship model formula is a sample regression model formula, where F is the theoretical value of water flow rate, a0, a1, a2, and a3 are the regression coefficients obtained when constructing the sample regression of the water pressure-water flow rate relationship model formula, where a0 is the first regression coefficient, a1 is the second regression coefficient, a2 is the third regression coefficient, a3 is the fourth regression coefficient, and p is the water pressure data in the water pressure-water flow rate sampling record. The average value of the water pressure data in the regression sample data used when constructing the water pressure-water flow rate relationship model formula is given.

[0056] Then, the calculated theoretical water flow rate F is subtracted from the water flow rate f in the water pressure and water flow rate sampling record, ΔF = Ff, to obtain the water flow rate deviation value ΔF.

[0057] For each water pressure and flow rate sampling record obtained, the corresponding water flow rate deviation value ΔF is calculated according to the above calculation process.

[0058] It should be noted that a water pressure-flow rate relationship model formula is pre-set for each secondary cooling water unit. When calculating the water flow rate deviation ΔF, the water pressure-flow rate relationship model formula used is the one corresponding to the secondary cooling water unit. The water pressure-flow rate relationship model formulas for each secondary cooling water unit are basically consistent in structure, all adopting a polynomial form, i.e. The differences are a0, a1, a2, a3, and The values ​​of a0, a1, a2, a3, and a4 are different. During normal production, the water pressure and flow rate relationship model formula for each secondary cooling water unit remains constant (a0, a1, a2, a3, and a4). (Unchanged) Only when the calculated result of the water pressure and water flow rate relationship model formula of a certain secondary cooling water unit deviates too much from the actual result will the water pressure and water flow rate relationship model formula of that secondary cooling water unit be reset during equipment maintenance.

[0059] When setting the water pressure and flow rate relationship model formula in advance, the formula is constructed by introducing the sample mean and using the least squares method for polynomial regression. Specifically, the water pressure and flow rate of a certain secondary cooling water unit are first sampled, and the sampled water pressure and flow rate data are used as regression sample data. Then, the least squares method is used to regress this set of regression sample data to obtain a sample regression model, which is then used as the water pressure and flow rate relationship model formula for the secondary cooling water unit.

[0060] Step 2.1.2, for the current secondary cooling water unit, calculate the average value E(ΔF) and the standard deviation σ(ΔF) of the water flow deviation values ΔF of all the water pressure and water flow sampling records.

[0061] Step 2.1.3, compare the average value E(ΔF) of the ΔF with the water flow deviation judgment threshold value E0 in the current flushing control parameter, and compare the standard deviation σ(ΔF) of the ΔF with the water flow fluctuation judgment threshold value σ0 in the current flushing control parameter, if E(ΔF) < E0 and σ(ΔF) < σ0, it is considered that the water pressure data and the water flow data in the water pressure and water flow sampling records of the current secondary cooling water unit are theoretically matched, and it is judged that there is no nozzle clogging in the current secondary cooling partition.

[0062] Otherwise, if E(ΔF) ≥ E0 or σ(ΔF) ≥ σ0, it is considered that the water pressure data and the water flow data in the water pressure and water flow sampling records of the current secondary cooling water unit are not matched, and it is judged that there is nozzle clogging in the current secondary cooling partition.

[0063] Step 2.2, if it is judged that there is no nozzle clogging in the current secondary cooling partition, the standard flushing water volume F0 in the current flushing control parameter is taken as the target flushing water volume, and the standard flushing time T0 in the current flushing control parameter is taken as the target flushing time.

[0064] If it is judged that there is nozzle clogging in the current secondary cooling partition, the strong flushing water volume F1 in the current flushing control parameter is taken as the target flushing water volume, and the strong flushing time T1 in the current flushing control parameter is taken as the target flushing time.

[0065] The setting of the target flushing water volume and the target flushing time is determined according to the clogging condition of the nozzle. Specifically, when it is judged that there is no nozzle clogging, the standard flushing water volume and the standard flushing time are used to flush the nozzle, which can not only prevent nozzle clogging, but also avoid wasting cooling water; when it is judged that there is nozzle clogging, the strong flushing water volume and the strong flushing time are used to flush the nozzle, which can flush out the clogging in the nozzle through strong water pressure, thereby achieving the effect of actively removing the clogging and avoiding further clogging of the nozzle.

[0066] Preferably, a data storage space is set in advance; the step 2.2 further comprises: the production control computer saves the water pressure and flow sampling records of the current secondary cooling subzone and the determined nozzle clogging information into the preset data storage space. The saved water pressure and flow sampling records and nozzle clogging information can be used as a reference for the subsequent secondary cooling water system maintenance, and through the data information, it can be known which region's nozzle exists the clogging phenomenon, and then the cooling water pipeline or nozzle in the region is replaced to keep the secondary cooling water system in good condition at all times.

[0067] The data storage space can be directly set in the production control computer, and the data storage space can be in the form of a database table.

[0068] Step 2.3, as the casting blank moves gradually, the tail of the casting blank gradually moves away from the end of the current secondary cooling subzone, and when the distance between the tail of the casting blank and the end of the current secondary cooling subzone reaches the tail of the casting blank leaving distance D in the current flushing control parameter, the secondary cooling water flow of the current secondary cooling water unit is set to the target flushing water amount, the valve device of the current secondary cooling water unit is opened, and the nozzles in the current secondary cooling subzone spray water, thereby flushing the nozzles in the current secondary cooling subzone.

[0069] It should be noted that the position of each secondary cooling subzone in the secondary cooling region is determined and unchanged from the time when the continuous casting machine is built, and then the continuous casting length position of the end of the secondary cooling subzone is a constant, and when the distance between the tail of the casting blank and the end of the current secondary cooling subzone is obtained, only the continuous casting length position of the tail of the casting blank is subtracted from the constant of the continuous casting length position of the end of the current secondary cooling subzone in the control program of the production control computer.

[0070] In step 2.3, the timing of flushing the nozzles is controlled when the distance between the tail of the casting blank and the end of the current secondary cooling subzone reaches the tail of the casting blank leaving distance D in the current flushing control parameter, and the purpose is to prevent the water sprayed by the nozzles in the current secondary cooling subzone from causing excessive cooling of the tail of the casting blank, so as to avoid the overcooling of the tail of the casting blank affecting the quality of the casting blank.

[0071] Step 2.4, the nozzle flushing process is timed, and when the time of the nozzle flushing reaches the target flushing time, the valve device of the current secondary cooling water unit is closed, thereby stopping the flushing of the nozzles. Thereafter, the current secondary cooling water unit is switched to the original water amount control mode to ensure that the subsequent casting operation of the continuous casting machine is not affected. After the casting blank completely leaves the secondary cooling region, the nozzles of all the secondary cooling subzones are flushed.

[0072] The nozzle anti-blocking flushing method of the embodiment is as follows: in the drawing process, after the tail of the casting blank leaves each secondary cooling subzone, the valve device of the secondary cooling water unit corresponding to the secondary cooling subzone is opened to flush the nozzle with water, so that the nozzle is prevented from being blocked. In the specific control process, before the nozzle is flushed with water, the water flow theoretical value matched with the sampling water pressure data is calculated by using the water pressure and water flow relationship model formula, and the actual blocking condition of the nozzle is judged according to the deviation between the water flow theoretical value and the sampling water flow data; if it is determined that the nozzle is not blocked, the nozzle is flushed with the standard flushing water volume and the standard flushing time, so that the nozzle is prevented from being blocked, and the waste of cooling water is avoided; if it is determined that the nozzle is blocked, the nozzle is flushed with the strong flushing water volume and the strong flushing time, so that the effect of actively removing the blocking material is achieved, and the nozzle is prevented from being further blocked.

[0073] An embodiment is provided below:

[0074] The embodiment takes the i th secondary cooling subzone in the secondary cooling zone as an example for description. The continuous casting length range of the secondary cooling subzone is [20m, 23m], and the continuous casting length position of the end of the secondary cooling subzone is 23m. In the water pressure and water flow relationship model formula corresponding to the secondary cooling subzone, the regression coefficients a0, a1, a2, and a3 take the values 515.2158, 1689.8385, -7963.5845, and 80198.57, respectively, The value of a4 is 0.1495, and the water pressure and water flow relationship model formula corresponding to the secondary cooling subzone is:

[0075] F = 515.2158 + 1689.8385 × (p-0.1495) + (-7963.5845) × (p-0.1495) 2 + 80198.57 × (p-0.1495) 3 .

[0076] The water pressure and water flow relationship model formula is derived as follows:

[0077] First, a group of sample data of water pressure and water flow of the i th secondary cooling water unit under normal conditions is sampled as regression sample data, and the sampled data is as follows:

[0078]

[0079] Then, according to the regression sample data, a polynomial regression is performed by using the least square method, and the mean value of the water pressure data in the regression sample data is also introduced into the polynomial, and the regression model is as follows:

[0080] F = 515.2158 + 1689.8385 x (p - 0.1495) + (-7963.5845) x (p - 0.1495) 2 + 80198.57 x (p - 0.1495) 3

[0081] The regression model is taken as the water pressure and water flow relationship model formula corresponding to the i-th secondary cooling sub-zone.

[0082] The above is the derivation process of the water pressure and water flow relationship model formula.

[0083] In the production control computer, a set of flushing control parameters is also set for the i-th secondary cooling sub-zone in the secondary cooling area, as shown in the following table:

[0084]

[0085] The method steps of the embodiment are as follows:

[0086] 1) During the casting of the continuous casting machine, the production control computer on site periodically samples the water pressure and water flow data of each secondary cooling water unit in the secondary cooling water system according to a preset sampling period of 5 seconds, and the water pressure p and water flow f data sampled in each sampling period are combined into a water pressure and water flow sampling record. The sampling data of the secondary cooling water unit corresponding to the i-th secondary cooling sub-zone are as follows:

[0087]

[0088]

[0089]

[0090]

[0091]

[0092]

[0093]

[0094] The sampling water pressure range [0.05, 0.25] Mpa is preset in the production control computer; if the sampled water pressure data exceeds the sampling water pressure range, the water pressure and water flow sampling record to which the water pressure data belongs is cleared and does not participate in the subsequent calculation process.

[0095] ​2) After the continuous casting machine finishes casting and enters the drawing process, the tail of the casting blank enters the secondary cooling area, and the tail of the casting blank sequentially passes through each secondary cooling sub-zone of the secondary cooling area until the tail of the casting blank leaves the secondary cooling area.

[0096] When the continuous casting length position of the tail of the casting blank exceeds the continuous casting length position of the end of the i-th secondary cooling sub-zone, the production control computer starts a nozzle flushing process for the i-th secondary cooling sub-zone.

[0097] The nozzle flushing process includes:

[0098] 2.1) According to the water pressure and water flow sampling records of the i-th secondary cooling water unit, it is judged whether there is a blockage in the nozzle in the i-th secondary cooling sub-zone, which includes:

[0099] 2.1.1) For each water pressure and water flow sampling record obtained by sampling, the water flow deviation value ΔF is calculated, which includes:

[0100] According to the water pressure and water flow relationship model formula corresponding to the i-th secondary cooling water unit, the water flow theoretical value F corresponding to the water pressure data is calculated; as described above, the water pressure and water flow relationship model formula is:

[0101] F = 515.2158 + 1689.8385 × (p-0.1495) + (-7963.5845) × (p-0.1495) 2 + 80198.57 × (p-0.1495) 3 ,

[0102] In the formula, F is the water flow theoretical value, and p is the water pressure data in the water pressure and water flow sampling record;

[0103] The water flow theoretical value F calculated is subtracted from the water flow f in the water pressure and water flow sampling record, ΔF=F-f, to obtain the water flow deviation value ΔF.

[0104] 2.1.2) The average value E(ΔF) of all ΔF is calculated, and the standard deviation σ(ΔF) of all ΔF is calculated, and the results are: E(ΔF)=-5.1, σ(ΔF)=15.5.

[0105] 2.1.3) In the flushing control parameters corresponding to the current i-th secondary cooling sub-zone, the water amount deviation judgment threshold E0=20, and the water amount fluctuation judgment threshold σ0=50, so E(ΔF)<E0 and σ(ΔF)<σ0, thereby judging that there is no blockage in the nozzle in the i-th secondary cooling sub-zone.

[0106] 2.2) The standard flush water amount F0 in the flush control parameter of the i-th secondary cooling water unit is taken as the target flush water amount, and the standard flush time T0 in the flush control parameter of the i-th secondary cooling water unit is taken as the target flush time. The water pressure and water flow amount sampling record of the i-th secondary cooling water unit and the determined nozzle clogging condition information are saved into the database table preset in the production control computer, and the corresponding continuous casting casting sequence number is recorded at the same time.

[0107] 2.3) When the distance between the i-th secondary cooling zone end and the billet tail reaches the billet tail departure distance D = 3 m in the flush control parameter of the i-th secondary cooling water unit, i.e. the continuous casting length position of the billet tail reaches 23 + 3 = 26 m (the continuous casting length position of the i-th secondary cooling zone end is 23 m), the secondary cooling water flow amount of the i-th secondary cooling water unit is set to the standard flush water amount F0 = 500 L / min as the target flush water amount, and then the valve device of the i-th secondary cooling water unit is opened to flush the nozzles in the i-th secondary cooling zone.

[0108] 2.4) The nozzle flushing process is timed, and when the nozzle flushing time reaches the standard flush time T0 = 60 s as the target flush time, the valve device of the i-th secondary cooling water unit is closed.

[0109] Thus far, the flushing process of the nozzles in the i-th secondary cooling zone is completed.

[0110] The above merely describes the preferred embodiments of the present application, and is not used to limit the protection scope of the present application, thus, any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for preventing clogging of a continuous casting secondary cooling nozzle, characterized by: For each secondary cooling sub-zone in the secondary cooling area, a set of flushing control parameters is preset, including the following parameters: the distance D from the end of the casting billet, the standard flushing water volume F0, the standard flushing time T0, the strong flushing water volume F1 and the strong flushing time T1; The nozzle anti-blocking flushing method comprises the following steps: Step 1, the continuous casting machine casts the casting billet, and during the casting process of the continuous casting machine, for each secondary cooling water unit in the secondary cooling water system, the water pressure and water flow data of the secondary cooling water unit are periodically sampled according to a preset sampling period, and the water pressure p and water flow f data obtained in each sampling period are combined into a water pressure and water flow sampling record; Step 2, after the continuous casting machine finishes casting and enters the drawing program, the end of the casting billet enters the secondary cooling area, and for each secondary cooling sub-zone in the secondary cooling area, the secondary cooling sub-zone is taken as the current secondary cooling sub-zone, the secondary cooling water unit corresponding to the current secondary cooling sub-zone is taken as the current secondary cooling water unit, and the flushing control parameter corresponding to the current secondary cooling sub-zone is taken as the current flushing control parameter, and then the nozzle flushing process of the current secondary cooling sub-zone is started; The flushing control parameters further include a water volume deviation judgment threshold E0 and a water volume fluctuation judgment threshold σ0; For each secondary cooling water unit in the secondary cooling water system, a water pressure and water flow relationship model formula is preset; The nozzle flushing process in step 2 comprises: Step 2.1, according to the water pressure and water flow sampling record of the current secondary cooling water unit, it is judged whether the nozzles in the current secondary cooling sub-zone are blocked; Step 2.1 comprises the following steps: Step 2.1.1, for each water pressure and water flow sampling record obtained, the water flow deviation value ΔF is calculated, which comprises: According to the water pressure data p in the water pressure and water flow sampling record and according to the water pressure and water flow relationship model formula corresponding to the current secondary cooling water unit, the water flow theoretical value F corresponding to the water pressure data is calculated; the water pressure and water flow relationship model formula is: The water pressure and water flow relationship model formula is a sample regression model formula, wherein F is a water flow theoretical value, a0, a1, a2, and a3 are regression coefficients obtained when the water pressure and water flow relationship model formula is constructed by sample regression, a0 is a first regression coefficient, a1 is a second regression coefficient, a2 is a third regression coefficient, a3 is a fourth regression coefficient, p is water pressure data in the water pressure and water flow sampling record, is an average value of water pressure data in regression sample data used when the water pressure and water flow relationship model formula is constructed by sample regression. The water flow theoretical value F calculated is subtracted from the water flow f in the water pressure and water flow sampling record, ΔF=F-f, to obtain the water flow deviation value ΔF; Step 2.1.2, for the current secondary cooling water unit, the average value E(ΔF) of all ΔF is calculated, and the standard deviation σ(ΔF) of all ΔF is calculated; Step 2.1.3, the average value E(ΔF) of the ΔF is compared with the water volume deviation judgment threshold E0 in the current flushing control parameter, and the standard deviation σ(ΔF) of the ΔF is compared with the water volume fluctuation judgment threshold σ0 in the current flushing control parameter, if E(ΔF)<E0 and σ(ΔF)<σ0, it is determined that the nozzles in the current secondary cooling sub-zone are not blocked; If E(ΔF)≥E0 or σ(ΔF)≥σ0, it is determined that the nozzles in the current secondary cooling sub-zone are blocked; According to the blocking condition of the nozzles, the target flushing water volume and the target flushing time are set.

2. The method according to claim 1, wherein the method is characterized by: The nozzle flushing process in step 2 comprises: Step 2.1, judging whether the nozzle in the current secondary cooling partition exists the blockage condition according to the water pressure and water flow sampling record of the current secondary cooling water unit; Step 2.2, if it is judged that the nozzle in the current secondary cooling partition has no blockage condition, then: taking the standard flushing water volume F0 in the current flushing control parameter as the target flushing water volume, and taking the standard flushing time T0 in the current flushing control parameter as the target flushing time; If it is judged that the nozzle in the current secondary cooling partition has the blockage condition, then: taking the strong flushing water volume F1 in the current flushing control parameter as the target flushing water volume, and taking the strong flushing time T1 in the current flushing control parameter as the target flushing time; Step 2.3, when the distance between the billet tail and the end of the current secondary cooling partition reaches the billet tail leaving distance D in the current flushing control parameter, setting the secondary cooling water flow of the current secondary cooling water unit as the target flushing water volume, opening the valve device of the current secondary cooling water unit, and flushing the nozzle in the current secondary cooling partition; Step 2.4, timing the nozzle flushing process, and when the time of the nozzle flushing reaches the target flushing time, then closing the valve device of the current secondary cooling water unit.

3. The method of claim 1, wherein the method further comprises: The sampling period is in the range of 1-10 seconds. ​ 4. The method according to claim 3, wherein the method is characterized by: The sampling period is set to 5 seconds.

5. The method of claim 1, wherein the method further comprises: The step 1 further comprises: if the water pressure data obtained by sampling exceeds the pre-set sampling water pressure range, then clearing the water pressure and water flow sampling record to which the water pressure data belongs. ​ 6. The method of claim 2, wherein the method further comprises: The step 2.2 further comprises: saving the water pressure and water flow sampling record of the current secondary cooling partition and the nozzle blockage condition information determined to the pre-set data storage space. ​

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