阅读说明：本技术 一种稳定结晶器铜板冷却水对流换热系数的系统和方法 (System and method for stabilizing convection heat exchange coefficient of crystallizer copper plate cooling water ) 是由 曾晶 王文学 王蓉 刘赵卫 于 2019-10-09 设计创作，主要内容包括：本发明提供了一种稳定结晶器铜板冷却水对流换热系数的系统和方法,包括结晶器铜板冷却水水量计算模块、T<Sub>mean</Sub>处理模块、水量控制模块、进水温度传感器、出水温度传感器、电磁流量计、气动调节阀。本发明方法在板坯连铸机的生产中,根据生产的钢种、拉速的变化,通过动态调整结晶器铜板冷却水的水量使冷却水在结晶器铜板水缝中的对流换热系数达到和保持在预定的目标值,实时平衡和消除冷却水温变化带来的影响,避免了因结晶器铜板冷却水供水温度的变化而导致结晶器的冷却强度偏离预定值的现象发生；降低了热裂纹敏感的钢种表面裂纹产生的几率,进一步提高了铸坯的表面质量。(The invention provides a system and a method for stabilizing the convective heat exchange coefficient of crystallizer copper plate cooling water mean The system comprises a processing module, a water quantity control module, a water inlet temperature sensor, a water outlet temperature sensor, an electromagnetic flowmeter and a pneumatic regulating valve. In the production of the slab caster, according to the change of the produced steel grade and the drawing speed, the method dynamically adjusts the water quantity of the cooling water of the copper plate of the crystallizer to ensure that the heat convection coefficient of the cooling water in the water gap of the copper plate of the crystallizer reaches and keeps a preset target value, balances and eliminates the influence caused by the change of the temperature of the cooling water in real time, and avoids the phenomenon that the cooling strength of the crystallizer deviates from the preset value due to the change of the water supply temperature of the cooling water of the copper plate of the crystallizer; the probability of surface cracks of the steel grade sensitive to the hot cracks is reduced, and the surface quality of the casting blank is further improved.)

1. The utility model provides a system for stabilize crystallizer copper cooling water convection heat transfer coefficient which characterized in that: comprises a pneumatic regulating valve (3), an electromagnetic flowmeter (4), a water quantity control module (5), a crystallizer copper plate cooling water quantity calculation module (6) and a T_meanThe device comprises a processing module (7), an inlet water temperature sensor (8) and an outlet water temperature sensor (9);

the inlet water temperature sensor (8) and the outlet water temperature sensor (9) are both connected with T_meanThe processing module (7) is electrically connected, T_meanThe processing module (7) is used for receiving signals of the inlet water temperature sensor (8) and the outlet water temperature sensor (9) in real time and calculating the average temperature T of inlet water and outlet water of cooling water of the copper plate of the crystallizer_meanElectromagnetic flowmeter (4), crystallizer copper plate cooling water volume calculation module (6) and pneumatic control valve (3) all are connected with water volume control module (5) electricity, water volume control module (5) are used for receiving water volume information and electromagnetic flowmeter (4) actual measurement's water volume information that crystallizer copper plate cooling water volume calculation module (6) sent in real time to send regulation control signal to pneumatic control valve (3) according to the difference between the two, T_meanThe processing module (7) is electrically connected with the crystallizer copper plate cooling water amount calculating module (6).

2. The system for stabilizing the convection heat exchange coefficient of the cooling water of the copper plate of the crystallizer as claimed in claim 1, wherein: pneumatic governing valve (3), electromagnetic flow meter (4), temperature sensor (8) of intaking locate in proper order on the pipeline between the delivery port of crystallizer copper cooling water tank (1) and crystallizer copper water inlet, go out on water temperature sensor (9) locate the pipeline between the water inlet of crystallizer copper (10) delivery port and crystallizer copper cooling water tank (1).

3. The system for stabilizing the convection heat exchange coefficient of the cooling water of the copper plate of the crystallizer as claimed in claim 1, wherein: the crystallizer copper plate cooling water amount calculation module (6) is used for acquiring T in real time_meanAccording to the cross section area A of a single water seam of the copper plate of the crystallizer_wsThe perimeter P of the cross section of a single water seam of the copper plate of the crystallizer_wsThe number n of the water gaps (15) of the crystallizer copper plate and a target value h of the convective heat transfer coefficient of the cooling water of the crystallizer copper plate_aimThe amount Q of the cooling water to be supplied to the mold copper plate (10) at present is calculated, and the information of the amount of the cooling water is sent to a water amount control module (5).

4. The system for stabilizing the convection heat exchange coefficient of the cooling water of the copper plate of the crystallizer as claimed in claim 2, wherein: and a pump (2) is arranged between the pneumatic regulating valve (3) and the crystallizer copper plate cooling water tank (1).

5. The system for stabilizing the convection heat exchange coefficient of the cooling water of the copper plate of the crystallizer as claimed in claim 2, wherein: and an outlet water temperature sensor (9) and a crystallizer copper plate cooling water radiator (11) are sequentially arranged on a pipeline between a water outlet of the crystallizer copper plate (10) and a water inlet of the crystallizer copper plate cooling water tank (1).

6. A method for stabilizing the convection heat exchange coefficient of the cooling water of the copper plate of the crystallizer, which uses the system for stabilizing the convection heat exchange coefficient of the cooling water of the copper plate of the crystallizer of claim 1, and is characterized by comprising the following steps of:

step 1) T_meanThe processing module (7) respectively acquires the water inlet temperature T of the current cooling water of the crystal copper plate through the water inlet temperature sensor (8) and the water outlet temperature sensor (9)_inAnd the temperature T of the outlet water_outAnd calculating the average temperature T of the cooling water inlet and outlet of the copper plate of the crystallizer_mean；

Step 2), the water quantity calculation module (6) of the crystallizer copper plate cooling water passes through T_meanProcessing module (7) real-time acquisitionT_meanAccording to the cross section area A of a single water seam of the copper plate of the crystallizer_wsThe perimeter P of the cross section of a single water seam of the copper plate of the crystallizer_wsThe number n of the water gaps of the crystallizer copper plate and the target value h of the convective heat transfer coefficient of the cooling water of the crystallizer copper plate_aimCalculating the water quantity Q of cooling water which is required to be supplied to the crystallizer copper plate (10) at present, and sending the water quantity information to a water quantity control module (5);

step 3) the water quantity control module (5) receives the water quantity information Q sent by the crystallizer copper plate cooling water quantity calculation module (6) and the water quantity information actually measured by the electromagnetic flow meter (4) in real time, sends an adjusting control signal to the pneumatic adjusting valve (3) according to the difference between the water quantity information Q and the water quantity information, and controls the convective heat transfer coefficient of the crystallizer copper plate cooling water to be stabilized to a target value h by adjusting the cooling water quantity supplied to the crystallizer copper plate_aim。

7. The method for stabilizing the convection heat exchange coefficient of the cooling water of the copper plate of the crystallizer as claimed in claim 6, wherein the method comprises the following steps: the process of calculating the cooling water quantity Q which should be supplied to the copper plate of the crystallizer currently by the crystallizer copper plate cooling water quantity calculation module (6) in the step 2) is as follows:

step (1) obtaining the average temperature T of inlet water and outlet water of cooling water of a crystallizer copper plate in real time_mean；

Step (2) according to the number n of the water gaps (15) of the crystallizer copper plate and the cross section area A of a single water gap of the crystallizer copper plate_wsThe perimeter P of the cross section of a single water seam of the copper plate of the crystallizer_wsCalculating the hydraulic diameter D of the water gap of the copper plate of the single crystallizer_h；

Setting three variables Q_up、Q_downAnd Q_curLet Q_up＝Q_max、Q_down＝0、Q_cur＝0.5(Q_up+Q_down) (ii) a Wherein Q is_maxSetting the maximum water quantity m for the cooling water of the copper plate of the crystallizer³/s；

Step (4) according to the average temperature T of the cooling water inlet and outlet of the crystallizer copper plate_meanBy Q_curCalculating the flow velocity V of cooling water in a water gap of the crystallizer copper plate, and cooling the crystallizer copper plateReynolds number Re corresponding to water_D(T_meanV) Nu corresponding to cooling water of copper plate of crystallizer_D(T_meanV) and the convection heat transfer coefficient h of cooling water of the copper plate of the crystallizer_cur(T_mean,V)；

Step (5) carrying out convection heat exchange coefficient h on cooling water of the copper plate of the crystallizer_cur(T_meanV) coefficient of heat transfer by convection with cooling water of copper plate of crystallizer_aimMaking a comparison if h_cur(T_mean,V)＜h_aimThen, set Q_down＝Q_cur，Q_cur＝0.5(Q_up+Q_down) If h is_cur(T_mean,V)＞h_aimThen, set Q_up＝Q_cur，Q_cur＝0.5(Q_up+Q_down) Repeating the step (4) until h_aim-Δh_down≤h(T_mean,V)≤h_aim+Δh_upOr (Q)_up-Q_down) < Δ Q, then let Q ═ Q_cur；

Wherein,. DELTA.h_downThe deviation of the convection heat transfer coefficient target of the cooling water of the copper plate of the crystallizer is W.m^-2·K^-1；Δh_upThe target deviation of the convection heat transfer coefficient of the cooling water of the copper plate of the crystallizer is W.m^-2·K^-1；

Step (6) obtaining the average temperature T of the inlet water and the outlet water of the cooling water of the copper plate of the current crystallizer_meanIf T this time_meanRelative to last time T_meanThe change exceeds the allowable deviation delta T of the average temperature of the cooling water inlet and outlet of the copper plate of the crystallizer_meanAnd (4) repeating the step (3), the step (4) and the step (5), otherwise, not adjusting the water quantity.

8. The method for stabilizing the convection heat exchange coefficient of the cooling water of the copper plate of the crystallizer as claimed in claim 7, wherein the method comprises the following steps: hydraulic diameter D of single crystallizer copper plate water seam_hThe calculation formula is as follows:

the calculation formula of the flow velocity V of the cooling water in the water gap of the copper plate of the crystallizer is as follows:

reynolds number Re corresponding to cooling water of crystallizer copper plate_D(T_meanV) the calculation formula is as follows:

in the formula, v (T)_mean) M is a function of the kinematic viscosity of water with respect to temperature²·s^-1；

Nu of Nu corresponding to cooling water of crystallizer copper plate_D(T_meanV) the calculation formula is as follows:

in the formula, f is a friction factor of a crystallizer copper plate water seam and is dimensionless; pr (Pr) of_D(T_mean) Is a function of the prandtl number of water with respect to temperature, dimensionless.

9. The method for stabilizing the convection heat exchange coefficient of the cooling water of the copper plate of the crystallizer as claimed in claim 7, wherein the method comprises the following steps: convective heat transfer coefficient h of cooling water of crystallizer copper plate_cur(T_meanV) the calculation formula is as follows:

in the formula, k (T)_mean) W.m as a function of the thermal conductivity of water with respect to temperature^-1·K^-1。

10. The method for stabilizing the convection heat exchange coefficient of the cooling water of the copper plate of the crystallizer as claimed in claim 8, wherein the method comprises the following steps: the friction factor f of the water seam of the copper plate of the crystallizer is calculated by the following formula:

f(T_mean,V)＝(0.790lnRe_D(T_mean,V)-1.64)^-2

function Pr of the Plantt number of water with respect to the temperature_D(T_mean) The following formula:

in the formula, ρ (T)_mean) Kg/m as a function of the density of the water with respect to the temperature^-3；c_p(T_mean) J.kg as a function of the specific heat capacity of water with respect to temperature^-1·K^-1；ν(T_mean) As a function m of the kinematic viscosity of water with respect to temperature²/s。

Technical Field

The invention belongs to the technical field of metallurgical continuous casting equipment, and particularly relates to a system and a method for stabilizing the convection heat exchange coefficient of cooling water of a crystallizer copper plate.

Background

In the production of the slab caster, the cooling water flow of the copper plate of the crystallizer needs to be reasonably adjusted according to the change of the produced steel grade and the pulling speed, and the heat convection coefficient of the copper plate in a water gap of the copper plate is changed, so that the aim of adjusting the cooling strength of the crystallizer is fulfilled. The rationality and scientificity of the convective heat transfer coefficient of cooling water in the water gap of the copper plate of the crystallizer are the key points for ensuring good surface quality of the casting blank.

Generally, when the flow rate variation rule of the cooling water of the copper plate of the crystallizer is determined, the temperature of the cooling water is regarded as a constant value (generally 35 ℃), and the influence caused by the variation of the water supply temperature of the cooling water of the copper plate of the crystallizer is not considered; in fact, the water supply temperature of the crystallizer copper plate cooling water can be greatly changed due to the influence of various factors such as weather, environment, different stages of production and the like; in the process, as the physical property of water changes along with the change of temperature, even under the condition of the same cooling water flow, the heat convection coefficient of the cooling water in the water gap of the copper plate of the crystallizer is different due to the difference of water supply temperature, so that the cooling intensity of the crystallizer deviates from a preset value; particularly, when steel grade sensitive to hot cracks is produced, if the water supply temperature of the cooling water of the copper plate of the crystallizer is changed greatly, the probability of cracks on the surface of a casting blank is obviously increased, and more hidden troubles are buried in the subsequent process.

Disclosure of Invention

The invention aims to provide a system for stabilizing the convection heat exchange coefficient of cooling water of a copper plate of a crystallizer, which overcomes the technical problems in the prior art.

The invention also aims to provide a method for stabilizing the convection heat exchange coefficient of the cooling water of the copper plate of the crystallizer, which avoids the phenomenon that the cooling strength of the crystallizer deviates from a preset value due to the change of the water supply temperature of the cooling water of the copper plate of the crystallizer; the probability of surface cracks of the steel grade sensitive to the hot cracks is reduced, and the surface quality of the casting blank is further improved.

Therefore, the technical scheme provided by the invention is as follows:

a system for stabilizing the convection heat exchange coefficient of cooling water of a crystallizer copper plate comprises a crystallizer copper plate cooling water quantity calculation module and a T_meanProcessing module, water quantity control module, inlet water temperature sensor and outlet water temperatureA sensor, an electromagnetic flowmeter, a pneumatic regulating valve;

the inlet water temperature sensor and the outlet water temperature sensor are both connected with T_meanProcess module electrical connection, said T_meanThe processing module is used for receiving signals of the water inlet temperature sensor and the water outlet temperature sensor in real time and calculating the average temperature T of the water inlet and the water outlet of the cooling water of the copper plate of the crystallizer_meanThe electromagnetic flow meter, the crystallizer copper plate cooling water volume calculation module and the pneumatic regulating valve are all electrically connected with the water volume control module, the water volume control module is used for receiving water volume information sent by the crystallizer copper plate cooling water volume calculation module and water volume information actually measured by the electromagnetic flow meter in real time and sending an adjusting control signal to the pneumatic regulating valve according to the difference between the two, T_meanThe processing module is electrically connected with the crystallizer copper plate cooling water amount calculating module.

Pneumatic governing valve, electromagnetic flowmeter, the temperature sensor of intaking locate in proper order on the pipeline between crystallizer copper cooling water tank's the delivery port and crystallizer copper water inlet, go out on water temperature sensor locates the pipeline between crystallizer copper delivery port and the water inlet of crystallizer copper cooling water tank.

The crystallizer copper plate cooling water amount calculation module is used for acquiring T in real time_meanAccording to the cross section area A of a single water seam of the copper plate of the crystallizer_wsThe perimeter P of the cross section of a single water seam of the copper plate of the crystallizer_wsThe number n of the water gaps of the crystallizer copper plate and the target value h of the convective heat transfer coefficient of the cooling water of the crystallizer copper plate_aimAnd calculating the water quantity of the cooling water which is required to be supplied to the copper plate of the crystallizer currently, and sending the water quantity information to a water quantity control module.

And a pump is arranged between the pneumatic regulating valve and the crystallizer copper plate cooling water tank.

And a water outlet temperature sensor and a crystallizer copper plate cooling water radiator are sequentially arranged on a pipeline between the water outlet of the crystallizer copper plate and the water inlet of the crystallizer copper plate cooling water tank.

A method for stabilizing the convection heat exchange coefficient of crystallizer copper plate cooling water is a system for stabilizing the convection heat exchange coefficient of crystallizer copper plate cooling water, and comprises the following steps:

step 1) T_meanThe processing module respectively acquires the water inlet temperature T of the current cooling water for the crystal copper plate through the water inlet temperature sensor and the water outlet temperature sensor_inAnd the temperature T of the outlet water_outAnd calculating the average temperature T of the cooling water inlet and outlet of the copper plate of the crystallizer_mean；

Step 2) a module for calculating the cooling water quantity of the copper plate of the crystallizer passes through T_meanProcessing module real-time acquisition of T_meanAccording to the cross section area A of a single water seam of the copper plate of the crystallizer_wsThe perimeter P of the cross section of a single water seam of the copper plate of the crystallizer_wsThe number n of the water gaps of the crystallizer copper plate and the target value h of the convective heat transfer coefficient of the cooling water of the crystallizer copper plate_aimCalculating the water quantity Q of cooling water which is required to be supplied to the copper plate of the crystallizer currently, and sending the water quantity information to a water quantity control module;

step 3) the water quantity control module receives water quantity information Q sent by the crystallizer copper plate cooling water quantity calculation module and water quantity information actually measured by the electromagnetic flowmeter in real time, sends an adjusting control signal to the pneumatic adjusting valve according to the difference between the water quantity information Q and the water quantity information, and controls the convective heat exchange coefficient of the crystallizer copper plate cooling water to be stabilized to a target value h by adjusting the cooling water quantity supplied to the crystallizer copper plate_aim。

The process of calculating the cooling water quantity Q which should be supplied to the crystallizer copper plate currently by the crystallizer copper plate cooling water quantity calculation module in the step 2) is as follows:

step (1) obtaining the average temperature T of inlet water and outlet water of cooling water of a crystallizer copper plate in real time_mean；

Step (2) according to the number n of the water gaps of the crystallizer copper plate and the cross section area A of a single water gap of the crystallizer copper plate_wsThe perimeter P of the cross section of a single water seam of the copper plate of the crystallizer_wsCalculating the hydraulic diameter D of the water gap of the copper plate of the single crystallizer_h；

Setting three variables Q_up、Q_downAnd Q_curLet Q_up＝Q_max、Q_down＝0、Q_cur＝0.5(Q_up+Q_down) (ii) a Wherein Q is_maxSetting the maximum water quantity m for the cooling water of the copper plate of the crystallizer³/s；

Step (4) according to the average temperature T of the cooling water inlet and outlet of the crystallizer copper plate_meanBy Q_curCalculating the flow velocity V of cooling water in a water gap of the copper plate of the crystallizer and the corresponding Reynolds number Re of the cooling water of the copper plate of the crystallizer_D(T_meanV) Nu corresponding to cooling water of copper plate of crystallizer_D(T_meanV) and the convection heat transfer coefficient h of cooling water of the copper plate of the crystallizer_cur(T_mean,V)；

Step (5) carrying out convection heat exchange coefficient h on cooling water of the copper plate of the crystallizer_cur(T_meanV) coefficient of heat transfer by convection with cooling water of copper plate of crystallizer_aimMaking a comparison if h_cur(T_mean,V)＜h_aimThen, set Q_down＝Q_cur，Q_cur＝0.5(Q_up+Q_down) If h is_cur(T_mean,V)＞h_aimThen, set Q_up＝Q_cur，Q_cur＝0.5(Q_up+Q_down) Repeating the step (4) until h_aim-Δh_down≤h(T_mean,V)≤h_aim+Δh_upOr (Q)_up-Q_down) < Δ Q, then let Q ═ Q_cur；

Wherein,. DELTA.h_downThe deviation of the convection heat transfer coefficient target of the cooling water of the copper plate of the crystallizer is W.m^-2·K^-1；Δh_upThe target deviation of the convection heat transfer coefficient of the cooling water of the copper plate of the crystallizer is W.m^-2·K^-1；

Step (6) obtaining the average temperature T of the inlet water and the outlet water of the cooling water of the copper plate of the current crystallizer_meanIf T this time_meanRelative to last time T_meanThe change exceeds the allowable deviation delta T of the average temperature of the cooling water inlet and outlet of the copper plate of the crystallizer_meanAnd (4) repeating the step (3), the step (4) and the step (5), otherwise, not adjusting the water quantity.

Hydraulic diameter D of copper plate water gap_hThe calculation formula is as follows:

the calculation formula of the flow velocity V of the cooling water in the water gap of the copper plate of the crystallizer is as follows:

reynolds number Re corresponding to cooling water of crystallizer copper plate_D(T_meanV) the calculation formula is as follows:

in the formula, v (T)_mean) M is a function of the kinematic viscosity of water with respect to temperature²·s^-1；

Nu of Nu corresponding to cooling water of crystallizer copper plate_D(T_meanV) the calculation formula is as follows:

in the formula, f is a friction factor of a crystallizer copper plate water seam and is dimensionless; pr (Pr) of_D(T_mean) Is a function of the prandtl number of water with respect to temperature, dimensionless.

Convective heat transfer coefficient h of cooling water of crystallizer copper plate_cur(T_meanV) the calculation formula is as follows:

in the formula, k (T)_mean) W.m as a function of the thermal conductivity of water with respect to temperature^-1·K^-1。

The friction factor f of the water seam of the copper plate of the crystallizer is calculated by the following formula:

f(T_mean,V)＝(0.790lnRe_D(T_mean,V)-1.64)^-2

function Pr of the Plantt number of water with respect to the temperature_D(T_mean) The following formula:

in the formula, ρ (T)_mean) Kg/m as a function of the density of the water with respect to the temperature^-3；c_p(T_mean) J.kg as a function of the specific heat capacity of water with respect to temperature^-1·K^-1；ν(T_mean) As a function m of the kinematic viscosity of water with respect to temperature²/s。

The invention has the beneficial effects that:

the invention balances and eliminates the influence caused by the change of the cooling water temperature in real time by dynamically adjusting the water quantity of the cooling water of the copper plate of the crystallizer, and avoids the phenomenon that the cooling strength of the crystallizer deviates from a preset value due to the change of the water supply temperature of the cooling water of the copper plate of the crystallizer; the probability of surface cracks of the steel grade sensitive to the hot cracks is reduced, and the surface quality of the casting blank is further improved.

In order to make the aforementioned and other objects of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.

Drawings

FIG. 1 is a schematic diagram of the system of the present invention;

FIG. 2 thermal conductivity of water versus temperature;

FIG. 3 is a graph of water density versus temperature;

FIG. 4 is a relationship of specific heat of water to temperature;

FIG. 5 is the kinematic viscosity of water versus temperature;

FIG. 6 is a plot of the prandtl number of water versus temperature;

FIG. 7 shows the convection heat transfer coefficient and T of the cooling water of the copper plate of the crystallizer_meanThe relationship of (1);

FIG. 8 is a schematic cross-sectional view of the relationship between the inner and outer copper plates of the mold and the cast slab.

Description of reference numerals:

1. a cooling water tank of the crystallizer copper plate; 2. a pump; 3. a pneumatic regulating valve; 4. an electromagnetic flow meter; 5. water (W)A quantity control module; 6. a water quantity calculating module for crystallizer copper plate cooling water; 7. t is_meanA processing module; 8. an inlet water temperature sensor; 9. an effluent temperature sensor; 10. a crystallizer copper plate; 11. a crystallizer copper plate cooling water radiator; 12. casting blanks; 13. an outer arc copper plate of the crystallizer; 14. an inner arc copper plate of the crystallizer; 15. and (5) water gaps of a crystallizer copper plate.

Detailed Description

The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will become apparent to those skilled in the art from the present disclosure.

The exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the embodiments described herein, which are provided for complete and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, the same units/elements are denoted by the same reference numerals.

Unless otherwise defined, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Further, it will be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.