Furnace head graphite electrode coolant flow control method, system and storage medium

Abstract

The present invention provides a flow control method, system and storage medium for graphite electrode coolant of a furnace head, belonging to the technical field of control or regulation system; the method comprises: determining a graphite electrode temperature target value during graphite electrode cooling; subtracting a graphite electrode temperature target value obtained based on a graphite electrode temperature target value time-varying curve from a graphite electrode temperature measurement value to obtain an operating variable feedback change value; determining a final operating variable value based on the operating variable feedback change value and an operating variable current value for real-time regulation of the coolant flow; the flow control method for graphite electrode coolant of a furnace head of the present invention dynamically regulates the graphite electrode temperature target value of a negative feedback control link of the coolant flow in combination with the graphite electrode temperature target value time-varying curve, which is beneficial to improving the cooling control quality of the graphite electrode of the furnace head, improving energy efficiency indicators and improving production efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of control or regulation systems, and in particular to a furnace head graphite electrode coolant flow control method, system and computer-readable storage medium. Background Art

[0002] As a device that uses high temperature to convert carbon materials into graphite, graphitization furnaces are widely used to produce negative electrode materials for batteries such as lithium-ion batteries and sodium-ion batteries. When the graphitization furnace is working, the graphite electrodes at both ends of the furnace need to be connected to the copper and aluminum bars outside the furnace to form a circuit. After power is turned on, high temperature is generated to complete the graphitization of the carbon materials in the furnace. Usually, the highest temperature of the graphitization transformation process of carbon materials in the furnace can reach about 3000℃. For each graphite electrode, one end is connected to the copper and aluminum bars outside the furnace through a power transmission clamp, and the other end is deep into the material in the furnace. Graphite is a material with relatively high thermal conductivity. Its working process has a very high temperature and a certain temperature change rate due to its own resistance heat generation and heat conduction of the materials in the furnace. High temperature will cause the oxidation of graphite electrodes to intensify, and the surface will produce obvious consumption or peeling; while the high temperature change rate such as rapid heating or rapid cooling will cause the graphite electrode to "thermally shock" due to the untimely release of thermal stress, causing cracks, surface peeling and even fracture. Therefore, the industry has vigorously developed the cooling technology of graphite electrodes.

[0003] However, in the currently known technical solutions, such as Chinese patents 201220304552.8, 201521103476.4, 201920540569.5, 202021246512.3, 202221959874.6, 202222986719.X and 202310542092.5, a lot of research has been carried out on the cooling device of the electrode, among which liquid cooling is the mainstream technical route for cooling graphite electrodes at present. However, there is little research on the control technology of the liquid cooling process of the furnace head graphite electrode. Therefore, it is necessary to propose a corresponding liquid cooling process control technology based on the characteristics of the working process of the furnace head graphite electrode, so as to improve the control quality of the cooling process and save operating costs. Summary of the invention

[0004] The main purpose of the present invention is to provide a furnace head graphite electrode coolant flow control method, system and computer-readable storage medium, aiming to solve the technical problem of how to improve the control quality of graphite electrode temperature and temperature change rate and save operating costs.

[0005] To achieve the above-mentioned purpose, the present invention provides a furnace head graphite electrode cooling liquid flow control method, wherein the graphite electrode is cooled based on a liquid-cooled heat exchanger in contact therewith, and is used to deliver power to the charge in the graphitization furnace; the method is applied to the furnace head graphite electrode cooling liquid flow control system to adjust the cooling liquid flow through the liquid-cooled heat exchanger in real time;

[0006] The method comprises:

[0007] During the cooling process of the graphite electrode, determine the target temperature value of the graphite electrode;

[0008] Subtracting the graphite electrode temperature target value from the graphite electrode temperature measurement value to obtain an operating variable feedback change value;

[0009] determining a final value of the manipulated variable for real-time adjustment of the coolant flow rate based on the manipulated variable feedback change value and the manipulated variable current value;

[0010] Wherein, the step of determining the target temperature value of the graphite electrode comprises:

[0011] Determine a time-varying curve of a graphite electrode temperature target value; the time-varying curve of the graphite electrode temperature target value is calculated based on a power transmission power curve;

[0012] The target temperature value of the graphite electrode is obtained by reading the target temperature value time-varying curve of the graphite electrode;

[0013] The step of determining the time-varying curve of the graphite electrode temperature target value comprises:

[0014] Obtaining the graphite electrode temperature target initial value and the graphite electrode temperature target maximum value;

[0015] Read the power transmission power corresponding to each moment in the power transmission power curve;

[0016] The target graphite electrode temperature time-varying curve is calculated by using the target graphite electrode temperature initial value, the target graphite electrode temperature maximum value and the corresponding power transmission at each moment.

[0017] Optionally, the step of calculating a time-varying curve of a graphite electrode temperature target value by using the graphite electrode temperature target initial value, the graphite electrode temperature target maximum value, and the power transmission power corresponding to each moment includes:

[0018] Determine the critical segment time when the accumulated power transmission reaches the preset multiple of the total power transmission;

[0019] When the power transmission time is zero, the graphite electrode temperature target value is set to the graphite electrode temperature target initial value;

[0020] When the power-on moment is the critical segmentation moment, set the graphite electrode temperature target value to the maximum graphite electrode temperature target value;

[0021] When the power-on moment is between the zero moment and the critical segmentation moment, input the initial graphite electrode temperature target value, the maximum graphite electrode temperature target value, and the power-on power corresponding to each moment into a preset time-varying curve calculation model to calculate the time-varying curve of the graphite electrode temperature target value.

[0022] Optionally, the preset time-varying curve calculation model includes:

[0023]

[0024] In the formula, Δt represents the time interval between adjacent moments; denote the graphite electrode temperature target value corresponding to the moment t = iΔt as F i , i = 1, 2,…, n; n is the power-off moment; the power-on power at the moment t = iΔt is P i ; let the graphite electrode temperature target value F0 = T corresponding to the moment t = 0 init , and let the graphite electrode temperature target values corresponding to all moments after the critical segmentation moment t = jΔt be T max , for the graphite electrode temperature target values F at all moments between t > 0 and t < jΔt m , calculated from the above formula;

[0025] T init and T max respectively represent the initial graphite electrode temperature target value and the maximum graphite electrode temperature target value, m = 1, 2,…, j - 1.

[0026] Optionally, the method further includes:

[0027] Using the initial graphite electrode temperature target value and a preset temperature rise threshold, correct the time-varying curve of the graphite electrode temperature target value to obtain a corrected time-varying curve of the graphite electrode temperature target value.

[0028] Optionally, the step of using the initial graphite electrode temperature target value and a preset temperature rise threshold to correct the time-varying curve of the graphite electrode temperature target value to obtain a corrected time-varying curve of the graphite electrode temperature target value includes:

[0029] Denote each moment in the power-on stage as the moment t = sΔt, where s = 0, 1,…, n, and correct the graphite electrode temperature target value F at each moment in the time-varying curve of the graphite electrode temperature target value i , and perform correction according to the following steps to obtain the final graphite electrode temperature target value T s at each moment and the corrected time-varying curve of the graphite electrode temperature target value:

[0030] Let s=0, and let the target temperature value of the graphite electrode at the corresponding moment be T0=F0;

[0031] Let s=1, if F1-T0>T c , then let the graphite electrode temperature target value at the corresponding time be T1=T0+T c , otherwise let T1=F1; where T c Indicates the preset temperature rise threshold;

[0032] Let s increase by 1 from its original value;

[0033] If s>n, the assignment of the graphite electrode temperature target value at each moment is terminated;

[0034] If s≤n, calculate the cumulative undertemperature value A at time t=sΔt s :

[0035]

[0036] Determine the graphite electrode temperature target value T at time t=sΔt s :

[0037] If F s -T s-1 >T c And T s-1 +T c ≤T max , then let T s =T s-1 +T c , and execute the step of increasing s by 1 on its original basis;

[0038] If F s -T s-1 >T c And T s-1 +T c >T max , then let the target temperature value of the graphite electrode at all times between t=sΔt and t=nΔt be T max ;

[0039] If F s -T s-1 ≤T c And the accumulated undertemperature value A s ≤0, then let T s =F s , and execute the step of increasing s by 1 on its original basis;

[0040] If F s -T s-1 ≤T c And the accumulated undertemperature value As >0 and T s-1 +T c ≤T max , then let T s =T s-1 +T c , and execute the step of increasing s by 1 on its original basis;

[0041] If F s -T s-1 ≤T c And the accumulated undertemperature value A s >0 and T s-1 +T c >T max , then let the target temperature value of the graphite electrode at all times between t=sΔt and t=nΔt be T max .

[0042] Optionally, the graphite electrode temperature target value time-varying curve also includes a graphite electrode temperature target value time-varying curve in a cooling stage after power transmission is completed, and the acquisition method is:

[0043] Let the target temperature of the graphite electrode at the beginning of the cooling phase be T max , and T c The rate of / Δt decreases continuously until the target temperature of the graphite electrode drops to T min The cooling phase is considered to be over when T min is the minimum target temperature of the graphite electrode.

[0044] Optionally, the step of determining a final value of the manipulated variable for real-time adjustment of the coolant flow rate based on the manipulated variable feedback change value and the manipulated variable current value comprises:

[0045] The sum of the manipulated variable feedback change value and the manipulated variable current value is calculated, and the sum is compared with the manipulated variable upper limit value and the manipulated variable lower limit value;

[0046] If the sum is between the upper limit of the manipulated variable and the lower limit of the manipulated variable, then the sum is the final value of the manipulated variable;

[0047] If the sum is higher than the manipulated variable upper limit value or lower than the manipulated variable lower limit value, the manipulated variable final value is the manipulated variable upper limit value or the manipulated variable lower limit value.

[0048] In addition, to achieve the above-mentioned purpose, the present invention also provides a furnace head graphite electrode coolant flow control system, the system is used to implement any one of the above furnace head graphite electrode coolant flow control methods, the system includes a graphite electrode, a measurement module, a storage module, a calculation module and an execution module:

[0049] The measuring module includes a temperature sensor for measuring the temperature of the graphite electrode in real time;

[0050] The storage module is used to store the measurement data of the measurement module;

[0051] The operation module is used to read data from the measurement module and calculate the final value of the operation variable; the execution module obtains the final value of the operation variable from the operation module and executes it.

[0052] Optionally, the operation module includes a feedback controller, a summer and a truncation device, wherein:

[0053] The feedback controller is used to calculate the feedback change value of the manipulated variable;

[0054] The summator is used to obtain the sum of the current value of the manipulated variable and the feedback change value of the manipulated variable and output it;

[0055] The truncation device is used to perform a truncation operation on the output result of the summer so as to control the final value of the manipulated variable to be between the upper limit value and the lower limit value of the manipulated variable.

[0056] Optionally, the feedback controller is a PID controller.

[0057] The present invention also provides a computer-readable storage medium, which stores a furnace head graphite electrode coolant flow control program, and the furnace head graphite electrode coolant flow control program is loaded and run by a processor according to any of the above-mentioned furnace head graphite electrode coolant flow control methods.

[0058] The beneficial effects of the present invention are:

[0059] The furnace head graphite electrode coolant flow control method provided by the present invention obtains a time-varying curve of a graphite electrode temperature target value based on a power transmission power curve, and performs real-time dynamic and fine adjustment on the graphite electrode temperature target value of a coolant flow negative feedback control link in combination with the graphite electrode temperature target value time-varying curve, which is beneficial to improving the cooling control quality of the furnace head graphite electrode, improving energy efficiency indicators, saving operating costs and improving production efficiency.

[0060] More specifically, the beneficial effects of the technical solution of the present invention are described below in combination with the principle of the technical solution of the present invention:

[0061] Usually, negative feedback closed-loop control is used in industry to achieve higher regulation quality, such as higher regulation accuracy, faster control response speed and lower operating cost. The main idea is to subtract the set target value from the real-time measurement value to obtain the feedback change value of the operating variable and make real-time adjustments. For the cooling process of the graphite electrode at the furnace head, the control purpose is to avoid the graphite electrode temperature value being too high and to avoid the graphite electrode temperature rising or falling too fast. Unlike the general cooling control object, the graphitization furnace is a periodic operation. In one cycle, it mainly goes through four stages: loading, power supply, cooling and unloading. Among them, the power supply (power heating) and cooling stages both involve the temperature control of the graphite electrode, and the graphite electrode undergoes huge temperature changes in these two stages: in the power supply stage, the entire graphitization furnace including the graphite electrode is powered on for heating, and the overall temperature of the graphitization furnace shows an upward trend. The temperature of the graphite electrode rises from room temperature to one or two hundred degrees Celsius or even higher; in the cooling stage, the graphite electrode is cooled from hundreds of degrees Celsius at the end of power supply to below 50°C to facilitate the subsequent manual unloading operation. Among them, the temperature rise of the graphitization furnace during the power transmission stage is also related to the power transmission curve. The power transmission curve is a curve of power transmission power variation over time, which is prepared in advance by on-site process personnel. Usually, the power is relatively small in the early stage to preheat the charge and promote the volatilization of moisture and impurities; while in the middle and late stages, it is increased to a larger power level to increase the heating speed of the charge and the graphitization conversion speed.

[0062] Therefore, how to scientifically and reasonably determine the temperature target value of the graphite electrode in the control process is a very critical technical issue.

[0063] If a fixed, low temperature target value is set for the graphite electrode, there will be the following three problems: First, after a certain period of power supply, the furnace temperature rises to a higher level, and the graphite electrode will also rise to a higher temperature through its thermal conductivity effect. At this time, it is actually difficult for the control system to maintain the graphite electrode at the preset temperature target value, which causes the control system to become saturated and actually lose its ability to adjust. Second, it causes the control system to work at a high load for a long time, resulting in high operating energy consumption and equipment depreciation rate, and causing a large amount of heat in the furnace to be dissipated through the graphite electrode, resulting in energy waste. Third, the cooling stage will cause the graphite electrode temperature to drop too quickly, which will damage the graphite electrode due to thermal stress problems and shorten the service life of the graphite electrode.

[0064] If a fixed, high temperature target value is set for the graphite electrode, there will be the following two problems: First, in the early stage of power transmission, the temperature of the graphite electrode rises too quickly, which will cause damage to the graphite electrode due to thermal stress and shorten the service life of the graphite electrode; second, the cooling stage will cause the temperature of the graphite electrode to drop too slowly, or even fail to drop to the required temperature for a long time, reducing work efficiency.

[0065] In fact, it is impossible to set a fixed temperature target value to meet the cooling control requirements of the graphite electrodes at the furnace head throughout the production process. Because no matter how large the temperature target value is set, there will always be a situation where this temperature target value can only better meet the needs of a certain period but cannot meet the needs of other periods.

[0066] Based on the above analysis, according to the specific characteristics of the graphitization furnace production process, the present invention designs a time-varying curve of the graphite electrode temperature target value. In this curve, the graphite electrode temperature target value changes every fixed time interval Δt; for the cooling process of the graphite electrodes at the furnace head of each production batch, it is necessary to read the graphite electrode temperature target value in real time and subtract it from the measured graphite electrode temperature to obtain the feedback change value of the operating variable, and determine the final value of the operating variable based on the feedback change value of the operating variable and the current value of the operating variable to be used for real-time adjustment of the coolant flow rate.

[0067] The time-varying curve of the graphite electrode temperature target value is obtained based on three major principles: The first principle is that the target value at each moment shall not exceed its maximum value T max ; the second principle is that with Δt as the time interval, the difference between the target value at any moment and its previous moment shall not exceed T c , that is, the rising or falling speed of the target value does not exceed T c / Δt; the third principle is to take into account the specific characteristics of the production process. On the premise of meeting the first principle and the second principle, actively and reasonably increase the target temperature of the graphite electrode gradually during the power-on process, so as to reduce the heat loss in the furnace, reduce the operating energy consumption of the cooling system and equipment loss, and ensure the response ability of the working process control system.

[0068] Specifically, the target temperature of the graphite electrode in the power-on stage is gradually increased mainly based on the power-on curve.

[0069] First, based on the proportionality coefficient k, the power-on stage is roughly divided into two sub-stages, and the division time point is the moment when the cumulative power-on work reaches k times the total power-on work, that is, the moment t = jΔt. Let the graphite electrode temperature target value corresponding to t = 0 be F0 = T init , and let the graphite electrode temperature target values corresponding to t = jΔt and all subsequent moments be T max .

[0070] Secondly, for all moments between t > 0 and t < jΔt, let the graphite electrode temperature target value in this time period start from T init and linearly increase to T max along with the cumulative power-on work, where the cumulative power-on work at t = mΔt and t = jΔt are respectively and .

[0071] Finally, the graphite electrode temperature target values ​​at all times are corrected according to the first principle and the second principle to obtain the final graphite electrode temperature target value.

[0072] No correction is made to the time t=0.

[0073] At t=Δt, let s=1, then t=sΔt=Δt, if F1-T0>T c , that is, the difference between the graphite electrode temperature target value at this moment and the graphite electrode temperature target value at the previous moment is greater than the temperature rise threshold T c , then let the graphite electrode temperature target value T1=T0+T c Lower the value to meet the second principle, otherwise let T1=F1.

[0074] For all moments when t>Δt, that is, when s≥2, take a certain moment, that is, the moment t=sΔt, as an example, and make corrections in the following order:

[0075] First, calculate the cumulative undertemperature value A at this moment s The under-temperature value is the sum of the differences between the graphite electrode temperature target value and the graphite electrode temperature target value at all times in history before this moment. If the cumulative under-temperature value A s >0 means that historically the graphite electrode temperature target value has been lowered several times to meet the second principle and there is a net under-temperature.

[0076] Then, based on the known graphite electrode temperature target value F at that time s and the graphite electrode temperature target value T at the previous moment s-1 , correct and obtain the target graphite electrode temperature T at that moment s :

[0077] (i) If F s -T s-1 >T c And T s-1 +T c ≤T max , indicating that if the graphite electrode temperature target value F at this moment is directly s As its target value, it violates the second principle, so it needs to be lowered. s =T s-1 +T c , and the graphite electrode temperature target value T at that moment is obtained after lowering s It also complies with the first principle;

[0078] (ii) If F s -T s-1 >T c And T s-1 +T c >Tmax , indicating that even if the target graphite electrode temperature at this moment is lowered to T s-1 +T c , but its value is greater than T max , which violates the first principle. Since the target temperature of the graphite electrode is already very large from this moment, the target temperature of the graphite electrode at all times between this moment and the end of power transmission t=nΔt is directly set to T max ;

[0079] (iii) If F s -T s-1 ≤T c And the accumulated undertemperature value A s ≤0, then let T s =F s , indicating that the target graphite electrode temperature F at this moment can be directly s as its target value;

[0080] (iv) If F s -T s-1 ≤T c And the accumulated undertemperature value A s >0 and T s-1 +T c ≤T max , then let T s =T s-1 +T c , which shows that although the graphite electrode temperature target value F at this moment can be directly s As its target value, but considering that there is a net under-temperature in history, in order to maintain the heating rate, the target temperature value of the graphite electrode at that moment is artificially increased as much as possible without violating the first principle and the second principle;

[0081] (v) If F s -T s-1 ≤T c And the accumulated undertemperature value A s >0 and T s-1 +T c >T max , indicating that if the target graphite electrode temperature at this moment is set to T in order to compensate for the net undertemperature in history, s-1 +T c If the graphite electrode temperature exceeds the target maximum value T max , since the target temperature of the graphite electrode is already very large from this moment, the target temperature of the graphite electrode at all times between this moment and the end of power transmission t=nΔt is directly set to T max .

[0082] Therefore, the present invention aims at the cooling problem of furnace head graphite electrodes, aims at the control needs of the maximum temperature and temperature change rate of the graphite electrodes themselves, and comprehensively considers the control accuracy, energy efficiency and production efficiency factors, and combines the power transmission curve and historical data to dynamically adjust the electrode temperature target value of the coolant flow negative feedback control link. This method is scientific and reasonable, safe and reliable, low in cost, and has wide applicability. It is beneficial to improve the cooling control quality of furnace head graphite electrodes, improve energy efficiency indicators and improve production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] Figure 1 1 is a flow chart of a method for controlling the flow rate of a furnace head graphite electrode coolant in an embodiment of the present invention;

[0084] Figure 2 Schematic diagram of a furnace head graphite electrode cooling flow control system according to an embodiment of the present invention;

[0085] Figure 3 It is a control node framework diagram of the furnace head graphite electrode cooling flow control method in an embodiment of the present invention;

[0086] Figure 4 It is a schematic diagram of the structure of the furnace head graphite electrode cooling flow control system in an embodiment of the present invention;

[0087] Figure 5 It is a schematic diagram of the process of obtaining the time-varying curve of the graphite electrode temperature target value in the power transmission stage in the furnace head graphite electrode cooling flow control method in an embodiment of the present invention.

[0088] Description of reference numerals:

[0089] 1. Graphite electrode; 2. Heat exchanger; 3. Controller; 4. Temperature sensor; 5. Liquid supply pump; 6. Refrigeration unit. DETAILED DESCRIPTION

[0090] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0091] Embodiment 1:

[0092] Please refer to Figure 1 , Figure 1 is a flow chart of a furnace head graphite electrode coolant flow control method according to an embodiment of the present invention; and combined with Figure 2 The present invention provides a furnace head graphite electrode cooling liquid flow control method, wherein the graphite electrode is cooled based on a liquid-cooled heat exchanger in contact therewith, and is used to deliver power to the charge in the graphitization furnace; the method is applied to the furnace head graphite electrode cooling liquid flow control system to adjust the cooling liquid flow through the liquid-cooled heat exchanger in real time;

[0093] The method comprises:

[0094] Step S10, determining a target temperature value of the graphite electrode during the cooling process of the graphite electrode;

[0095] Step S20, subtracting the graphite electrode temperature target value from the graphite electrode temperature measurement value to obtain an operating variable feedback change value;

[0096] Step S30, determining a final value of the manipulated variable based on the manipulated variable feedback change value and the manipulated variable current value for real-time adjustment of the coolant flow rate;

[0097] In this embodiment, during the cooling process of the furnace head graphite electrode of each production batch, the graphite electrode temperature target value is read in real time and subtracted from the graphite electrode temperature measurement value to obtain the operating variable feedback change value, and the operating variable final value is determined based on the operating variable feedback change value and the operating variable current value for real-time adjustment of the coolant flow rate;

[0098] The above graphite electrode temperature target value changes at fixed time intervals Δt, and the graphite electrode temperature target value at each moment is read based on the graphite electrode temperature target value time-varying curve;

[0099] Specifically, the step of determining the target temperature value of the graphite electrode includes:

[0100] Determine a time-varying curve of a graphite electrode temperature target value; the time-varying curve of the graphite electrode temperature target value is calculated based on a power transmission power curve;

[0101] The target temperature value of the graphite electrode is obtained by reading the target temperature value time-varying curve of the graphite electrode;

[0102] The step of determining the time-varying curve of the graphite electrode temperature target value comprises:

[0103] Obtaining the graphite electrode temperature target initial value and the graphite electrode temperature target maximum value;

[0104] Read the power transmission power corresponding to each moment in the power transmission power curve;

[0105] The target graphite electrode temperature time-varying curve is calculated by using the target graphite electrode temperature initial value, the target graphite electrode temperature maximum value and the corresponding power transmission at each moment.

[0106] like Figure 5 As shown, the graphite electrode temperature target value time-varying curve includes the graphite electrode temperature target value time-varying curve in the power transmission stage obtained by calculating the power transmission power curve, and the acquisition steps are:

[0107] Step S1: Denote the starting time of power transmission as the moment t = 0. After i time intervals, it is the moment t = iΔt. The moment t = nΔt is the end time of power transmission. The power transmission at the moment t = iΔt is P i , calculate the moment (the key segmentation moment) when the cumulative power transmission reaches k times the total power transmission and denote it as the moment t = jΔt. Here, k is a proportionality coefficient between 0 and 1, and j satisfies the following conditions:

[0108] (1)

[0109] Step S2: Denote the target value of the graphite electrode temperature corresponding to the moment t = iΔt as F i , where i = 1, 2, …, n; let the target value of the graphite electrode temperature corresponding to the moment t = 0 be F0 = T init , and let the target values of the graphite electrode temperature corresponding to the moment t = jΔt and all subsequent moments be T max . For all moments between t > 0 and t < jΔt, calculate the corresponding target values of the graphite electrode temperature T respectively by the following formula: m :

[0110] (2)

[0111] Δt represents the time interval between adjacent moments; here, T init and T max are respectively the initial value of the graphite electrode temperature target and the maximum value of the graphite electrode temperature target, where m = 1, 2, …, j - 1;

[0112] Step S3: Denote each moment in the power transmission stage as the moment t = sΔt, where s = 0, 1, …, n. For the target values of the graphite electrode temperature at each moment obtained in Step S2, perform the following sub - steps to correct them to obtain the final target values of the graphite electrode temperature T s and the time - varying curve of the corrected target value of the graphite electrode temperature:

[0113] Sub - step S3.1: Let s = 0, and let the target value of the graphite electrode temperature at the corresponding moment T0 = F0;

[0114] Sub - step S3.2: Let s = 1. If F1 - T0 > T c , then let the target value of the graphite electrode temperature at the corresponding moment T1 = T0 + T c , otherwise let T1 = F1;

[0115] Sub - step S3.3: Increase s by 1 on its original basis;

[0116] Sub - step S3.4: If s > n, then transfer to Sub - step S3.9, otherwise enter Sub - step S3.5;

[0117] Sub-step S3.5: Calculate the cumulative undertemperature value A at time t=sΔt s :

[0118] (3)

[0119] Sub-step S3.6: Determine the target graphite electrode temperature T at time t=sΔt s :

[0120] (i) If F s -T s-1 >T c And T s-1 +T c ≤T max , then let T s =T s-1 +T c , then proceed to sub-step S3.7;

[0121] (ii) If F s -T s-1 >T c And T s-1 +T c >T max , then go to sub-step S3.8;

[0122] (iii) If F s -T s-1 ≤T c And the accumulated undertemperature value A s ≤0, then let T s =F s , then proceed to sub-step S3.7;

[0123] (iv) If F s -T s-1 ≤T c And the accumulated undertemperature value A s >0 and T s-1 +T c ≤T max , then let T s =T s-1 +T c , then proceed to sub-step S3.7;

[0124] (v) If F s -T s-1 ≤T c And the accumulated undertemperature value A s >0 and T s-1 +T c >T max , then go to sub-step S3.8;

[0125] Sub-step S3.7, proceed to sub-step S3.3;

[0126] Sub-step S3.8, let the target temperature value of the graphite electrode at all times between t=sΔt and t=nΔt be T max ;

[0127] Sub-step S3.9, ending the assignment of the graphite electrode temperature target value at each moment;

[0128] Above T c is the preset temperature rise threshold.

[0129] Furthermore, in the above furnace head graphite electrode coolant flow control method, the graphite electrode temperature target value time-varying curve also includes a graphite electrode temperature target value time-varying curve in the cooling stage after the power transmission is completed, and the acquisition method is: let the graphite electrode temperature target value at the start time of the cooling stage be T max , and T c The rate of Δt decreases continuously until the target temperature of the graphite electrode drops to T min The cooling phase is considered to be over when T min is the minimum target temperature of the graphite electrode.

[0130] Furthermore, in the above furnace head graphite electrode coolant flow control method, the step of determining the final value of the operating variable for real-time adjustment of the coolant flow based on the operating variable feedback change value and the operating variable current value comprises:

[0131] The sum of the manipulated variable feedback change value and the manipulated variable current value is calculated, and the sum is compared with the manipulated variable upper limit value and the manipulated variable lower limit value;

[0132] If the sum is between the upper limit of the manipulated variable and the lower limit of the manipulated variable, then the sum is the final value of the manipulated variable;

[0133] If the sum is higher than the manipulated variable upper limit value or lower than the manipulated variable lower limit value, the manipulated variable final value is the manipulated variable upper limit value or the manipulated variable lower limit value.

[0134] Preferably, in the above furnace head graphite electrode coolant flow control method, the greater the amount by which the graphite electrode temperature measurement value corresponding to the current moment exceeds the graphite electrode temperature target value, the greater the output operating variable feedback change value thereof.

[0135] Preferably, in the above furnace head graphite electrode coolant flow control method, the final value of the operating variable is the valve opening or the liquid supply pump speed for controlling the coolant flow.

[0136] Furthermore, the above furnace head graphite electrode coolant flow control method further comprises:

[0137] After the coolant cools the graphite electrode through the liquid-cooled heat exchanger, it flows into the refrigeration unit for cooling, and then flows back to the liquid-cooled heat exchanger through the liquid supply pump for continuous circulation.

[0138] Embodiment 2:

[0139] like Figure 2~Figure 4 As shown, the present invention provides a furnace head graphite electrode coolant flow control system, the system is used to implement the furnace head graphite electrode coolant flow control method, the system includes a graphite electrode, a measurement module, a storage module, a calculation module and an execution module:

[0140] The measuring module includes a temperature sensor for measuring the temperature of the graphite electrode in real time;

[0141] The storage module is used to store the measurement data of the measurement module;

[0142] The operation module is used to read data from the measurement module and calculate the final value of the operation variable; the execution module obtains the final value of the operation variable from the operation module and executes it.

[0143] Further, continue to refer to Figure 2~Figure 4 , the above furnace head graphite electrode coolant flow control system, the operation module includes a feedback controller, a summer and a truncation device, wherein:

[0144] The feedback controller is used to calculate the feedback change value of the manipulated variable;

[0145] The summator is used to obtain the sum of the current value of the manipulated variable and the feedback change value of the manipulated variable and output it;

[0146] The truncation device is used to perform a truncation operation on the output result of the summer so as to control the final value of the manipulated variable to be between the upper limit value and the lower limit value of the manipulated variable.

[0147] Preferably, in the above furnace head graphite electrode coolant flow control system, the feedback controller is a PID controller.

[0148] The present invention also provides a computer-readable storage medium, which stores a furnace head graphite electrode coolant flow control program, and the furnace head graphite electrode coolant flow control program is loaded and run by a processor according to the above-mentioned furnace head graphite electrode coolant flow control method.

[0149] Among them, the method implemented when the furnace head graphite electrode coolant flow control program is executed can refer to the various embodiments of the furnace head graphite electrode coolant flow control method of the present invention, which will not be repeated here.

[0150] In a more specific embodiment:

[0151] Please refer to Figures 1 to 5 Understand the following specific embodiment.

[0152] The graphite electrode of a furnace head is cooled by a heat exchanger in contact with it. The coolant flows through the heat exchanger, and the flow rate of the coolant is controlled online in real time by adjusting the speed of the liquid supply pump. After the coolant flows out of the refrigeration unit, it is pressurized by the liquid supply pump and transported to the heat exchanger, where the graphite electrode is indirectly cooled; the temperature of the coolant rises after heat exchange, and then flows back to the refrigeration unit for cooling and then restarts the next cycle.

[0153] The values ​​of the relevant parameters in this embodiment are: time interval Δt=10min, n=300, that is, the total duration of the power transmission stage=300×10min=3000min=50h, the proportional coefficient k=0.6, and the target initial value of the graphite electrode temperature T init =50℃, maximum target temperature of graphite electrode T max =250℃, temperature rise threshold T c =5℃, the minimum target temperature of graphite electrode is T min =50℃.

[0154] First, the process of obtaining the time-varying curve of the graphite electrode temperature target value during the power transmission stage is introduced.

[0155] Based on the transmission power curve, it is found that the time when the cumulative power transmission work reaches k times the total power transmission work is t=2200min=220×10min, that is, j=220. Specifically, at t=2200min, the cumulative power transmission work is 0.60 times the total power transmission work, and at the previous moment, t=2190min, the cumulative power transmission work is 0.59 times the total power transmission work.

[0156] Then the graphite electrode temperature target value at each moment is obtained: Let the graphite electrode temperature target value F0=T corresponding to the moment t=0 init =50℃; let the target temperature of graphite electrode corresponding to t=2200min and all times thereafter be T max =250℃; for all moments in (0, 2200min), let the graphite electrode temperature target value increase linearly with the accumulated power transmission: the faster the accumulated power transmission increases, the faster the graphite electrode temperature target value increases. In the whole process of [0, 2200min], the graphite electrode temperature target value increases monotonically from 50℃ to 250℃. The graphite electrode temperature target value in the time period [2200, 3000min] is 250℃.

[0157] Each moment of the power transmission stage is denoted as t=sΔt, where s=0, 1,…,n. The obtained graphite electrode temperature target value at each moment is corrected to obtain the final graphite electrode temperature target value T at each moment. s .

[0158] Let s = 0, and let the target value of the graphite electrode temperature at the corresponding moment be T0 = F0 = 50°C.

[0159] Let s = 1, and look up to get F1 = 54°C, F1 - T0 = 54 - 50 = 4 < T c , which does not meet the condition of "F1 - T0 > T c ", so let T1 = F1 = 54°C.

[0160] Let s increase by 1 on its original basis, that is, s = 1 + 1 = 2 < n; calculate the cumulative under-temperature value A at the moment t = sΔt = 2Δt = 20 min s =(F1 - T1)=54 - 54 = 0; look up to get F2 = 57°C, F2 - T1 = 57 - 54 = 3°C ≤ T c , obviously meeting the condition (iii) of sub-step S3.6: "F s -T s-1 ≤T c and the cumulative under-temperature value A s ≤0", so let T2 = F2 = 57°C.

[0161] Then let s increase by 1 on its original basis again, that is, s = 2 + 1 = 3 < n; calculate the cumulative under-temperature value A at the moment t = sΔt = 3Δt = 30 min s =(F1 - T1)+(F2 - T2)=(54 - 54)+(57 - 57)=0; look up to get F3 = 63°C, F3 - T2 = 63 - 57 = 6°C > T c , T s-1 +T c =T2 + T c =57 + 5 = 62°C ≤ T max , obviously meeting the condition (i) of sub-step S3.6: "F s -T s-1 >T c and T s-1 +T c ≤T max ", so let T3 = T2 + T c =57 + 5 = 62°C.

[0162] Then let s increase by 1 on its original basis again, that is, s = 3 + 1 = 4 < n; calculate the cumulative under-temperature value A at the moment t = sΔt = 4Δt = 40 min s =(F1 - T1)+(F2 - T2)+(F3 - T3)=(54 - 54)+(57 - 57)+(63 - 62)=1 > 0; look up to get F4 = 66°C, F4 - T3 = 66 - 62 = 4°C < T c , T s-1 +T c =T3 + T c=62 + 5 = 67℃ ≤ T max , obviously satisfying the condition (iv) of sub-step S3.6: "F s -T s-1 ≤ T c and the cumulative under-temperature value A s > 0 and T s-1 + T c ≤ T max ". Therefore, let T4 = T3 + T c = 62 + 5 = 67℃.

[0163] Then let s increase by 1 on its original basis, i.e., s = 4 + 1 = 5 < n. Due to space limitations, the correction process for the time periods corresponding to s = 5 to s = 218 is omitted.

[0164] When s = 219, it is found that F 219 = 248℃, while T 218 = 246℃. Calculate the cumulative under-temperature value A s = 0 at the moment t = sΔt = 219Δt = 2190 min. Obviously, it satisfies the condition (iii) of sub-step S3.6: "F s -T s-1 ≤ T c and the cumulative under-temperature value A s ≤ 0". Therefore, let T 219 = F 219 = 248℃.

[0165] Then let s increase by 1 on its original basis, i.e., s = 219 + 1 = 220 < n.

[0166] When s = 220, it is found that F 220 = 250℃, while T 219 = 248℃. Calculate the cumulative under-temperature value A s = 0 at the moment t = sΔt = 220Δt = 2200 min. Obviously, it satisfies the condition (iii) of sub-step S3.6: "F s -T s-1 ≤ T c and the cumulative under-temperature value A s ≤ 0". Therefore, let T 220 = F 220 = 250℃.

[0167] Then let s increase by 1 on its original basis, i.e., s = 220 + 1 = 221 < n.

[0168] When s = 221, it is found that F 221 = 250℃, while T 220 = 250℃. Calculate the cumulative under-temperature value A s= 0, which obviously satisfies the condition (iii) of sub-step S3.6: “F s -T s-1 ≤T c And the accumulated undertemperature value A s ≤0", so let T 221 =F 221 =250℃.

[0169] Then let s increase by 1, that is, s=221+1=222 <n。

[0170] After that, the corresponding graphite electrode temperature target values ​​from s=222 to s=300 are also 250°C.

[0171] When s=300, let s increase by 1 on its original basis, that is, s=300+1=301>n, so the assignment of the graphite electrode temperature target value at each moment is completed.

[0172] The time-varying curve of the graphite electrode temperature target value in the cooling stage after power transmission is obtained as follows: Let the graphite electrode temperature target value at the start of the cooling stage be T max = 250℃, and T c / Δt=5℃ / 10min=0.5℃ / min, and the temperature of the graphite electrode decreases until the target value reaches T min =50℃, the cooling stage is considered to be over.

[0173] The operating variable of this embodiment is the rotation speed of the liquid supply pump, the upper limit value of the operating variable = 3000 r / min, the lower limit value = 500 r / min, the feedback controller is a PID controller with only a proportional coefficient, and its control logic is: subtract the graphite electrode temperature target value from the graphite electrode temperature measurement value and multiply by -10 as the operating variable feedback change value, wherein the units of the graphite electrode temperature target value and the graphite electrode temperature measurement value are ℃, and the unit of the operating variable feedback change value is r / min. For example, at a certain moment, the target value of graphite electrode temperature = 195℃, the measured value of graphite electrode temperature = 192℃, the current value of the operating variable, that is, the current speed of the liquid supply pump = 2300 r / min, then the operating variable feedback change value = (195-192)×(-10) = -30r / min, the sum of the operating variable feedback change value and the operating variable current value = 2300-30 = 2270r / min, the sum is between the upper limit and the lower limit of the operating variable, then the final value of the operated variable after adjustment = 2270r / min.

[0174] In this embodiment, the control needs of the maximum temperature and temperature change rate of the graphite electrode itself are taken into consideration, and the control accuracy, energy efficiency and production efficiency factors are comprehensively considered. The electrode temperature target value of the coolant flow negative feedback control link is dynamically adjusted in combination with the power transmission curve and historical data. This method is scientific and reasonable, safe and reliable, low in cost, and has wide applicability. It is beneficial to improve the cooling control quality of the furnace head graphite electrode, improve energy efficiency indicators and increase production efficiency.

[0175] It should be understood by those skilled in the art that embodiments of the present invention may be provided as methods, devices, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0176] The present invention is described with reference to flowcharts and / or block diagrams of methods, apparatuses, and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as a combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the process in the flowchart. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0177] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0178] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0179] It should be noted that in the claims, any reference signs placed between brackets shall not be construed as limiting the claims. The word "comprising" does not exclude the presence of components or steps not listed in the claim. The word "a" or "an" preceding a component does not exclude the presence of a plurality of such components. The invention may be implemented by means of hardware comprising several different components and by means of a suitably programmed computer. In a unit claim enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third etc. does not indicate any order. These words may be interpreted as names.

[0180] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0181] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A furnace head graphite electrode coolant flow control method, characterized in that: The graphite electrode is cooled based on a liquid-cooled heat exchanger in contact with it, and is used to deliver power and electricity to the charge in the graphitization furnace; The method is applied to a furnace head graphite electrode coolant flow control system to adjust the coolant flow through a liquid-cooled heat exchanger in real time; The method comprises: During the cooling process of the graphite electrode, determine the target temperature value of the graphite electrode; Subtracting the graphite electrode temperature target value from the graphite electrode temperature measurement value to obtain an operating variable feedback change value; determining a final value of the manipulated variable for real-time adjustment of the coolant flow rate based on the manipulated variable feedback change value and the manipulated variable current value; Wherein, the step of determining the target temperature value of the graphite electrode comprises: Determine a time-varying curve of a graphite electrode temperature target value; the time-varying curve of the graphite electrode temperature target value is calculated based on a power transmission power curve; The target temperature value of the graphite electrode is obtained by reading the target temperature value time-varying curve of the graphite electrode; The step of determining the time-varying curve of the graphite electrode temperature target value comprises: Obtaining the graphite electrode temperature target initial value and the graphite electrode temperature target maximum value; Read the power transmission power corresponding to each moment in the power transmission power curve; Calculate the time-varying curve of the graphite electrode temperature target value by using the graphite electrode temperature target initial value, the graphite electrode temperature target maximum value and the power transmission power corresponding to each moment; The step of calculating a time-varying curve of a graphite electrode temperature target value by using the graphite electrode temperature target initial value, the graphite electrode temperature target maximum value, and the power transmission power corresponding to each moment comprises: Determine the critical segment time when the accumulated power transmission reaches the preset multiple of the total power transmission; When the power transmission time is zero, the graphite electrode temperature target value is set to the graphite electrode temperature target initial value; When the power transmission moment is a critical segment moment, the graphite electrode temperature target value is set to the maximum value of the graphite electrode temperature target; When the power transmission time is between the zero time and the key segment time, the graphite electrode temperature target initial value, the graphite electrode temperature target maximum value and the power transmission power corresponding to each time are input into the preset time-varying curve calculation model to calculate the graphite electrode temperature target value time-varying curve; The preset time-varying curve calculation model includes: where Δt represents the time interval between adjacent moments; denote the target value of the graphite electrode temperature corresponding to the moment t = iΔt as F i , i = 1, 2, …, n; n is the power-off moment; the power transmission power at the moment t = iΔt is P i ; let the target value of the graphite electrode temperature corresponding to the moment t = 0 be F0 = T init , and let the target values of the graphite electrode temperature corresponding to all moments after the key segmentation moment t = jΔt be T max , for the target values of the graphite electrode temperature F at all moments between t > 0 and t < jΔt m , they are calculated from the above formula; T init and T max They represent the target initial value of graphite electrode temperature and the target maximum value of graphite electrode temperature, respectively, m=1, 2,…,j-1; The method further comprises: Using the graphite electrode temperature target initial value and the preset temperature rise threshold, the graphite electrode temperature target value time-varying curve is corrected to obtain a corrected graphite electrode temperature target value time-varying curve; The step of correcting the time-varying curve of the graphite electrode temperature target value by using the graphite electrode temperature target initial value and the preset temperature rise threshold value to obtain a corrected time-varying curve of the graphite electrode temperature target value comprises: Each moment of the power transmission stage is t=sΔt, where s=0, 1,…,n. The graphite electrode temperature target value F at each moment in the graphite electrode temperature target value time-varying curve is i , perform correction according to the following steps to obtain the final graphite electrode temperature target value T at each moment s And the modified graphite electrode temperature target value time-varying curve: Let s=0, and let the target temperature value of the graphite electrode at the corresponding moment be T0=F0; Let s=1, if F1-T0>T c , then let the graphite electrode temperature target value at the corresponding time be T1=T0+T c , otherwise let T1=F1; where T c Indicates the preset temperature rise threshold; Let s increase by 1 from its original value; If s>n, the assignment of the graphite electrode temperature target value at each moment is terminated; If s≤n, calculate the cumulative undertemperature value A at time t=sΔt s : Determine the graphite electrode temperature target value T at time t=sΔt s : If F s -T s-1 >T c And T s-1 +T c ≤T max , then let T s =T s-1 +T c , and execute the step of increasing s by 1 on its original basis; If F s -T s-1 >T c And T s-1 +T c >T max , then let the target temperature value of the graphite electrode at all times between t=sΔt and t=nΔt be T max ; If F s -T s-1 ≤T c And the accumulated undertemperature value A s ≤0, then let T s =F s , and execute the step of increasing s by 1 on its original basis; If F s -T s-1 ≤T c And the accumulated undertemperature value A s >0 and T s-1 +T c ≤T max , then let T s =T s-1 +T c , and execute the step of increasing s by 1 on its original basis; If F s -T s-1 ≤T c And the accumulated undertemperature value A s >0 and T s-1 +T c >T max , then let the target temperature value of the graphite electrode at all times between t=sΔt and t=nΔt be T max .

2. The furnace head graphite electrode coolant flow control method according to claim 1, characterized in that: The graphite electrode temperature target value time-varying curve also includes the graphite electrode temperature target value time-varying curve in the cooling stage after power transmission is completed, and the acquisition method is: Let the target temperature of the graphite electrode at the beginning of the cooling phase be T max , and T c The rate of / Δt decreases continuously until the target temperature of the graphite electrode drops to T min The cooling phase is considered to be over when T min is the minimum target temperature of the graphite electrode.

3. The furnace head graphite electrode coolant flow control method according to claim 1, characterized in that: The step of determining a final value of the manipulated variable for real-time adjustment of the coolant flow rate based on the manipulated variable feedback change value and the manipulated variable current value comprises: The sum of the manipulated variable feedback change value and the manipulated variable current value is calculated, and the sum is compared with the manipulated variable upper limit value and the manipulated variable lower limit value; If the sum is between the upper limit of the manipulated variable and the lower limit of the manipulated variable, then the sum is the final value of the manipulated variable; If the sum is higher than the manipulated variable upper limit value or lower than the manipulated variable lower limit value, the manipulated variable final value is the manipulated variable upper limit value or the manipulated variable lower limit value.

4. A furnace head graphite electrode coolant flow control system, characterized in that: The system is used to implement the furnace head graphite electrode coolant flow control method according to any one of claims 1 to 3, and the system includes a graphite electrode, a measurement module, a storage module, a calculation module and an execution module: The measuring module includes a temperature sensor for measuring the temperature of the graphite electrode in real time; The storage module is used to store the measurement data of the measurement module; The operation module is used to read data from the measurement module and calculate the final value of the operation variable; the execution module obtains the final value of the operation variable from the operation module and executes it.

5. The furnace head graphite electrode coolant flow control system according to claim 4, characterized in that: The operation module includes a feedback controller, a summer and a truncation device, wherein: The feedback controller is used to calculate the feedback change value of the manipulated variable; The summator is used to obtain the sum of the current value of the manipulated variable and the feedback change value of the manipulated variable and output it; The truncation device is used to perform a truncation operation on the output result of the summer so as to control the final value of the manipulated variable to be between the upper limit value and the lower limit value of the manipulated variable.

6. A computer-readable storage medium, characterized in that: A furnace head graphite electrode coolant flow control program is stored therein, and the furnace head graphite electrode coolant flow control program is loaded and run by a processor to execute the furnace head graphite electrode coolant flow control method described in any one of claims 1 to 3.

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