METHOD FOR CONTROLLING STABILITY OF GAS FLOW AT PERIPHERY OF BLAST FURNACE

Abstract

A method for controlling stability of gas flow at the periphery of a blast furnace, including the following steps: constructing a database; and selecting blast furnace operating parameters satisfying a first preset condition from the database to generate an instruction for setting the blast furnace operating parameters for a next operating stage. The first preset condition includes: PD<a preset value PD0, and the blast furnace operation parameters corresponding to a minimum value of PU are selected when the condition is satisfied.

Claims

1. A method for controlling stability of gas flow at the periphery of a blast furnace, comprising the following steps: constructing a database of blast furnace operating parameters, the database comprising the number of gas flow peaks of lower part of the blast furnace PD, the number of gas flow peaks of upper part of the blast furnace PU, blast furnace feed, a distribution system, an air supply system and a cooling system collected in production history; and selecting the blast furnace operating parameters satisfying a first preset condition from the database to generate an instruction for setting the blast furnace operating parameters for a next operating stage; wherein the first preset condition comprises: the number of gas flow peaks of lower part of the blast furnace PD<a preset value PD0, and the blast furnace operating parameters corresponding to a minimum value of the number of gas flow peaks of upper part of the blast furnace PU are selected when the condition PD<PD0 is satisfied; wherein a statistical method for the number of gas flow peaks of lower part of the blast furnace PD and the number of gas flow peaks of upper part of the blast furnace PU is as follows: calculating a correlation coefficient R.sub.k between a standard deviation of temperature T.sub.k of the k.sup.th cooling stave and a standard deviation of heat load of the blast furnace TL respectively, wherein k=5, 6, . . . , 12; counting the number of gas flow peaks, corresponding to a section of cooling stave with the highest correlation coefficient R.sub.k in the 5.sup.th to 9.sup.th sections of cooling staves, as the number of gas flow peaks of lower part of the blast furnace PD; and counting the number of gas flow peaks, corresponding to a section of cooling stave with the highest correlation coefficient R.sub.k in the 10.sup.th to 12.sup.th sections of cooling staves, as the number of gas flow peaks of upper part of the blast furnace PU.

2. The method for controlling stability of gas flow at the periphery of a blast furnace according to claim 1, wherein the step constructing a database of blast furnace operating parameters specifically comprises: dividing the statistically obtained number of gas flow peaks of lower part of the blast furnace PD into different grades in order of magnitude, to obtain the number of gas flow peaks of lower part of the blast furnace PD in different ranges, and taking average values of the blast furnace operating parameters in a same grade; and the first preset condition comprises: a maximum value in a range of the grade of the number of gas flow peaks of lower part of the blast furnace PD<a preset value PD0, and the average value of the blast furnace operating parameters corresponding to the minimum value of the number of gas flow peaks of upper part of the blast furnace PU is selected when the condition is satisfied.

3. The method for controlling stability of gas flow at the periphery of a blast furnace according to claim 1, wherein the correlation coefficient R.sub.k between the standard deviation of temperature T.sub.k of the k.sup.th cooling stave and the standard deviation of heat load of the blast furnace TL is calculated by the following equation: $R_k=\frac{\mathrm{Cov}\left(T_k,\mathrm{TL}\right)}{\sqrt{\mathrm{Var}\left(T_k\right).Math.\mathrm{Var}\left(\mathrm{TL}\right)}},$ wherein Cov(T.sub.k, TL) is a sample covariance of T.sub.k and TL in several units of time within a preset time, Var(T.sub.k) is a variance of T.sub.k in several units of time within a preset time, and Var(TL) is a variance of TL in several units of time within a preset time.

4. The method for controlling stability of gas flow at the periphery of a blast furnace according to claim 3, wherein the standard deviation of temperature of the k.sup.th cooling stave T.sub.k is calculated by the following equation: $T_k=\underset{j=1}{\overset{m}{.Math.}}\sqrt{\frac{1}{n-1}\underset{i=1}{\overset{n}{.Math.}}{\left(T_i-\stackrel{}{T}\right)}^2},$ wherein m is the number of temperature collection points on the k.sup.th cooling stave, j=1, . . . , m, T.sub.i is the i.sup.th temperature data of a temperature collection point on the k.sup.th cooling stave, n is the number of temperature samples in unit time, i=1, . . . , n, and T is an average temperature in unit time.

5. The method for controlling stability of gas flow at the periphery of a blast furnace according to claim 4, wherein the temperature of the cooling stave is collected by thermocouples arranged on the cooling stave, and a sample dataset is subjected to removal of outliers and removal of data under unstable working conditions to obtain a final processed sample dataset.

6. The method for controlling stability of gas flow at the periphery of a blast furnace according to claim 3, wherein the standard deviation of heat load of the cooling stave, $\mathrm{TL}=\sqrt{\frac{1}{n-1}\underset{i=1}{\overset{n}{.Math.}}{\left({\mathrm{TL}}_i-\stackrel{\_}{\mathrm{TL}}\right)}^2},$ wherein TL.sub.i is the heat load of the blast furnace when the i.sup.th temperature data is collected, n is the number of heat load samples in unit time, i=1, . . . , n, and TL is average heat load in unit time.

7. The method for controlling stability of gas flow at the periphery of a blast furnace according to claim 6, wherein the heat load of the blast furnace TL.sub.i=c.Math.F(T.sub.out-T.sub.in), wherein c is specific heat capacity of water, F is a flow rate of cooling water in the cooling stave, T.sub.out is an outlet water temperature of the cooling stave, and T.sub.in is an inlet water temperature of the cooling stave.

8. The method for controlling stability of gas flow at the periphery of a blast furnace according to claim 1, wherein the statistical method for the number of gas flow peaks comprises: collecting multiple temperature data of the cooling stave, the multiple temperature data being sorted by collection time; removing interference temperature data from the multiple temperature data, and determining several analytical temperature data; performing moving average processing on respective analytical temperature data in order according to the determination order of the several analytical temperature data; and counting the number of gas flow peaks based on the respective analytical temperature data T.sub.p subjected to the moving average processing, and defining the temperature data satisfying both a second preset condition and a third preset condition as one gas flow peak, wherein the number of gas flow peaks of each section of cooling stave is a sum of the number of gas flow peaks at multiple temperature collection points on the cooling stave in a preset time; the second preset condition is: T.sub.p>T.sub.p1 and T.sub.pT.sub.p+1, wherein T.sub.p1, T.sub.p and T.sub.p+1 are the (p1).sup.th, p.sup.th and (p+1).sup.th analytical temperature data respectively; and the third preset condition is: the analytical temperature data of the 5.sup.th to 9.sup.th cooling staves satisfy T.sub.p/T>1.05, or the analytical temperature data of the 10.sup.th to 12.sup.th cooling staves satisfy T.sub.p/T>1, wherein T is an average temperature in unit time.

9. The method for controlling stability of gas flow at the periphery of a blast furnace according to claim 8, wherein the moving average processing comprises: creating a moving window of a preset step size, and according to the set step size, starting from a first temperature data among the several analytical temperature data, moving forward in the order of collection time until a last temperature data enters the moving window; and after each time of moving, taking an average value of temperature data in the moving window as the analytical temperature data of an intermediate collection point in the moving window, in order to obtain several analytical temperature data after several times of moving.

10. The method for controlling stability of gas flow at the periphery of a blast furnace according to claim 8, wherein the interference temperature data comprise: continuous multiple constant temperature data, temperature data outside a preset range (T.sub.min, T.sub.max), as well as temperature data in 2 hours before opening, during opening and in 2 hours after closing of a back-drafting valve.

11. The method for controlling stability of gas flow at the periphery of a blast furnace according to claim 1, wherein the blast furnace feed parameters comprise Zn content, alkali metal content and sintered fine ore percentage in the blast furnace feed; the distribution system parameters comprise a maximum tilting angle, charge level height and periphery load O/C, wherein O is the number of ore circles in the two outermost grades/(the total number of ore circles x batch ore charge), and C is the number of coke circles in the two outermost grades/(the total number of coke circlesbatch coke charge); the air supply system comprises tuyere area, tuyere length, blast volume and oxygen content; and the cooling system comprises an inlet water temperature and a flow rate of cooling water in the cooling stave.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] FIG. 1 is a cross-sectional structural diagram of a blast furnace top device in an embodiment of the present disclosure.

DETAILED DESCRIPTION

[0041] The following will provide a detailed description of the present disclosure in conjunction with specific implementations shown in the accompanying drawings. However, the present disclosure is not limited by these implementations, and any structural, method or functional changes, made by those of ordinary skill in the art, based on these implementations are included in the scope of the protection of the present disclosure.

[0042] An implementation of the present disclosure provides a method for controlling stability of gas flow at the periphery of a blast furnace to achieve smooth running of the blast furnace, and avoid abnormal furnace conditions such as accretion of the blast furnace wall and the appearance of channels on the charge level.

[0043] Referring to a blast furnace top device in FIG. 1, a furnace body 100 includes a throat 1, a stack 2, a shaft 3, a belly 4 and a hearth 5 from top to bottom. A cooling stave 6 of the blast furnace covers the furnace body 100. The cooling stave 6 is divided into a total of 12 sections from bottom to top, and the 12 sections of cooling staves are numbered sequentially from bottom to top. The 1.sup.st to the 3.sup.rd sections of cooling staves cover the hearth 5, the 4.sup.th to the 5th sections of cooling staves cover the belly 4, the 6.sup.th section of the cooling stave covers the shaft 3, and the 7.sup.th to the 12.sup.th sections of cooling staves cover the stack 2. Copper cooling staves with good thermal conductivity and impact resistance are used for the cooling staves in the 1.sup.st to 9.sup.th sections, while cast iron cooling staves with good wear resistance are used in the 10.sup.th to 12.sup.th sections.

[0044] Referring to the blast furnace top device shown in FIG. 1, the steps of the control method are introduced below.

Step: A Database of Blast Furnace Operating Parameters is Constructed.

[0045] The database includes the number of gas flow peaks of lower part of the blast furnace PD, the number of gas flow peaks of upper part of the blast furnace PU, blast furnace feed, a distribution system, an air supply system and a cooling system collected in production history.

[0046] Specifically, the blast furnace feed parameters include Zn content, alkali metal content and sintered fine ore percentage in the blast furnace feed. Regulation of these parameters can avoid blast furnace wall accretion.

[0047] The distribution system parameters include a maximum tilting angle, charge level height and periphery load O/C, where O is the number of ore circles in the two outermost grades/(the total number of ore circles x batch ore charge), C is the number of coke circles in the two outermost grades/(the total number of coke circlesbatch coke charge), and the periphery load O/C characterizes the ratio of the thickness of ore to the thickness of coke at the periphery of the blast furnace. The thickness of a charge layer and the shape of the charge level at the periphery of the blast furnace can be regulated with the parameters to affect rolling of the furnace charge and avoid formation of gas flow channels.

[0048] The air supply system includes tuyere area, tuyere length, blast volume and oxygen content. The blast flow rate and kinetic energy entering the blast furnace can be regulated with the parameters to directly affect the distribution of airflow throughout the blast furnace.

[0049] The cooling system includes an inlet water temperature and a flow rate of cooling water in the cooling stave 6. Regulation of the parameters can regulate cooling capacity of cooling water in the cooling stave 6 and further affect heat exchange in the blast furnace.

Step: The Blast Furnace Operating Parameters Satisfying a First Preset Condition are Selected from the Database to Generate an Instruction for Setting the Blast Furnace Operating Parameters for a Next Operating Stage.

[0050] The first preset condition includes: the number of gas flow peaks of lower part of the blast furnace PD<a preset value PD0, and the blast furnace operating parameters corresponding to a minimum value of the number of gas flow peaks of upper part of the blast furnace PU are selected when the condition PD<PD0 is satisfied.

[0051] A statistical method for the number of gas flow peaks of lower part of the blast furnace PD and the number of gas flow peaks of upper part of the blast furnace PU is as follows: [0052] a correlation coefficient R.sub.k between a standard deviation of temperature T.sub.k of the k.sup.th cooling stave and a standard deviation of heat load of the blast furnace TL is calculated respectively, where k=5, 6, . . . , 12; [0053] the number of gas flow peaks, corresponding to a section of cooling stave with the highest correlation coefficient R.sub.k in the 5.sup.th to 9.sup.th sections of cooling staves, is counted as the number of gas flow peaks of lower part of the blast furnace PD; and [0054] the number of gas flow peaks, corresponding to a section of cooling stave with the highest correlation coefficient R.sub.k in the 10.sup.th to 12.sup.th sections of cooling staves, is counted as the number of gas flow peaks of upper part of the blast furnace PU.

[0055] Cohesive zones in the blast furnace are mainly located in the areas such as the belly 4, shaft 3 and the lower areas of stack 2, which correspond to the areas of the 5.sup.th to the 9.sup.th sections of cooling staves. The distribution of the cohesive zones at the periphery of the blast furnace is reflected in the areas of the cooling staves, and the formation and dropping of slag skull are mainly concentrated in these areas. The heat load in these areas is high, and copper cooling staves with better cooling performance are used in these areas to achieve excellent cooling effects. The upper areas of the blast furnace stack 2, which correspond to the areas of the 10.sup.th to 12.sup.th sections of cooling staves, and belong to a dry zone of the blast furnace. The furnace wall in these areas mainly bears physical friction caused by drop of furnace charge and thermal expansion of the furnace charge. In addition, the distribution of gas flow passing through the cohesive zones inside the blast furnace is also reflected on the areas of the cooling staves. These areas use the cast iron cooling staves with good friction resistance to prolong the service life of the blast furnace. By calculating and counting the correlation coefficient R.sub.k between the standard deviation of temperature T.sub.k of each section of cooling stave and the standard deviation of heat load of the blast furnace TL, the upper cooling stave and lower cooling stave in the section that is most affected by temperature changes in the blast furnace can be respectively reflected. Further, the number of gas flow peaks of the section of cooling stave reflects the fluctuation of the gas flow at the periphery of the corresponding blast furnace. Further, based on the historical data of the number of gas flow peaks of lower part of the blast furnace PD and the number of gas flow peaks of upper part of the blast furnace PU, an optimal combination of blast furnace operating parameters is selected for the next operating stage of the blast furnace. Thus, targeted regulation of parameters that affect the gas flow at the inner periphery of the blast furnace can be performed to guide smooth running of the blast furnace and avoid abnormal blast furnace conditions caused by blindly setting the blast furnace operating parameters according to operator experience.

[0056] Specifically, in this implementation, the step constructing a database of blast furnace operating parameters specifically includes the following: the statistically obtained number of gas flow peaks of lower part of the blast furnace PD are divided into different grades in order of magnitude, to obtain the number of gas flow peaks of lower part of the blast furnace PD in different ranges, and average values of the blast furnace operating parameters in a same grade is taken.

[0057] The first preset condition includes: a maximum value in a range of the grade of the number of gas flow peaks of lower part of the blast furnace PD<a preset value PD0, and the average value of the blast furnace operating parameters corresponding to the minimum value of the number of gas flow peaks of upper part of the blast furnace PU is selected when the condition is satisfied.

[0058] Specifically, the correlation coefficient R.sub.k between the standard deviation of temperature T.sub.k of the k.sup.th cooling stave and the standard deviation of heat load of the blast furnace TL is calculated by the following equation:

[00004]$R_k=\frac{\mathrm{Cov}\left(T_k,\mathrm{TL}\right)}{\sqrt{\mathrm{Var}\left(T_k\right).Math.\mathrm{Var}\left(\mathrm{TL}\right)}},$

[0059] Where Cov(T.sub.k, TL) is a sample covariance of T.sub.k and TL in several units of time within a preset time, Var(T.sub.k) is a variance of T.sub.k in several units of time within a preset time, and Var(TL) is a variance of TL in several units of time within a preset time.

[0060] Further, the standard deviation of temperature of the k.sup.th cooling stave T is calculated by the following equation:

[00005]$T_k=\underset{j=1}{\overset{m}{.Math.}}\sqrt{\frac{1}{n-1}\underset{i=1}{\overset{n}{.Math.}}{\left(T_i-\stackrel{}{T}\right)}^2},$ [0061] where m is the number of temperature collection points on the k.sup.th cooling stave, j=1, . . . , m, T.sub.i is the i.sup.th temperature data of a temperature collection point on the k.sup.th cooling stave, n is the number of temperature samples in unit time, i=1, . . . , n, and T is an average temperature in unit time.

[0062] Specifically, the temperature of the cooling stave 6 is collected by thermocouples arranged on the cooling stave 6, and in this embodiment, m thermocouples are installed on each section of cooling stave, which means that each section of cooling stave has m temperature collection points.

[0063] During the temperature collection process, a sample dataset is subjected to removal of outliers and removal of data under unstable working conditions and other interference temperature data to obtain a final processed sample dataset, thereby removing abnormal data that may interfere with the final detection results, and providing precise regulation over the operation of the blast furnace.

[0064] In this implementation, the outliers include continuous multiple constant temperature data, and temperature data outside a preset range (T.sub.min, T.sub.max); and the data under unstable working conditions include temperature data in 2 hours before opening, during opening and in 2 hours after closing of a back-drafting valve.

[0065] Further, the standard deviation of heat load of the cooling stave 6 TL is calculated by the following equation:

[00006]$\mathrm{TL}=\sqrt{\frac{1}{n-1}\underset{i=1}{\overset{n}{.Math.}}{\left({\mathrm{TL}}_i-\stackrel{\_}{\mathrm{TL}}\right)}^2},$ [0066] where TL.sub.i is the heat load of the blast furnace when the i.sup.th temperature data is collected, n is the number of heat load samples in unit time, i=1, . . . , n, and TL is average heat load in unit time.

[0067] The calculation formula for the heat load of the blast furnace TL.sub.i is calculated by the following equation:

[00007]${\mathrm{TL}}_i=c.Math.F\left(T_{\mathrm{out}}-T_{\mathrm{in}}\right),$ [0068] where c is specific heat capacity of water, F is the flow rate of cooling water in the cooling stave 6, T.sub.out is the outlet water temperature of the cooling stave 6, and T.sub.in is the inlet water temperature of the cooling stave 6.

[0069] The correlation coefficient R.sub.k between the standard deviation of temperature T.sub.k of each section of cooling stave and the standard deviation of heat load of the blast furnace TL characterizes the fluctuation of temperature of each section of cooling stave and the quantity of heat exchange of the cooling stave 6 of the entire blast furnace body 100.

[0070] Further, in the method for controlling stability of gas flow at the periphery of a blast furnace, the statistical method for the number of gas flow peaks includes the following: [0071] multiple temperature data of the cooling stave 6 are collected, and the multiple temperature data are sorted by collection time; [0072] interference temperature data are removed from the multiple temperature data, and several analytical temperature data are determined; [0073] moving average processing is performed on respective analytical temperature data in order according to the determination order of the several analytical temperature data; and [0074] the number of gas flow peaks is counted based on the respective analytical temperature data T.sub.p subjected to the moving average processing, and the temperature data satisfying both a second preset condition and a third preset condition is defined as one gas flow peak, where the number of gas flow peaks of each section of cooling stave is a sum of the number of gas flow peaks at multiple temperature collection points on the cooling stave in a preset time.

[0075] The second preset condition is: T.sub.p>T.sub.p1 and T.sub.p>T.sub.p+1, where T.sub.p1, T.sub.p and T.sub.p+1 are the (p1).sup.th, p.sup.th and (p+1).sup.th analytical temperature data respectively.

[0076] The third preset condition is: the analytical temperature data of the 5.sup.th to 9.sup.th cooling staves satisfy T.sub.p/T>1.05, or the analytical temperature data of the 10.sup.th to 12.sup.th cooling staves satisfy T.sub.p/T>1, where T is an average temperature in unit time.

[0077] The number of gas flow peaks of lower part of the blast furnace PD is obtained by processing the temperature data of the section of cooling stave with the highest correlation coefficient R.sub.k in the 5.sup.th to 9.sup.th sections of cooling staves by the above method. The third preset condition satisfies the following: the analytical temperature data of the 5.sup.th to 9.sup.th sections of cooling staves satisfy T.sub.p/T>1.05. That is, a gas flow peak refers to the analytical temperature data being at least greater than the average value in unit time and greater than the previous and following adjacent analytical temperature data.

[0078] The number of gas flow peaks of upper part of the blast furnace PU is obtained by processing the temperature data of the section of cooling stave with the highest correlation coefficient R.sub.k in the 10.sup.th to 12.sup.th sections of cooling staves by the above method. The third preset condition satisfies the following: the analytical temperature data of the 10.sup.th to 12.sup.th sections of cooling staves satisfy T.sub.p/T>1. That is, a gas flow peak refers to the analytical temperature data being greater than the average value in unit time and greater than the previous and following adjacent analytical temperature data.

[0079] In this way, the number of gas flow peaks reflects the fluctuation of temperature of the cooling stave 6 within a preset time. Based on the number of gas flow peaks of the upper cooling stave and lower cooling stave in the section that is most affected by temperature changes in the blast furnace, and according to history data, an appropriate range of the number of gas flow peaks of lower part of the blast furnace PD and the number of gas flow peaks of upper part of the blast furnace PU is selected for regulating and guiding the blast furnace operating parameters.

[0080] Further, the moving average processing includes the following: [0081] a moving window of a preset step size is created, and according to the set step size, starting from a first temperature data among the several analytical temperature data, forward moving processing is performed in the order of collection time until a last temperature data enters the moving window; and [0082] after each time of moving, an average value of temperature data in the moving window is taken as the analytical temperature data of an intermediate collection point in the moving window, in order to obtain several analytical temperature data after several times of moving.

[0083] By means of the moving average processing, a smooth and regular curve of temperature changes can be obtained, thereby eliminating burrs, counting and quantifying the fluctuation of temperature, i.e. the gas flow peaks, and further establishing a quantitative relationship between the temperature of the cooling stave 6 and the gas flow at the periphery of the blast furnace.

[0084] Further, the interference temperature data include: continuous multiple constant temperature data, temperature data outside a preset range (T.sub.min, T.sub.max), as well as temperature data in 2 hours before opening, during opening and in 2 hours after closing of a back-drafting valve. The temperature data are subjected to removal of outliers and removal of data under unstable working conditions and other interference temperature data, thereby removing abnormal data that may interfere with the final detection results, and providing precise regulation over the operation of the blast furnace.

[0085] The method for controlling stability of gas flow at the periphery of a blast furnace of the present disclosure is further illustrated through a specific embodiment as follows.

[0086] The temperature of the cooling stave 6 is collected by the m thermocouples arranged on each section of cooling stave every 2 minutes, to collect multiple temperature data of the 5.sup.th to 12.sup.th sections of cooling staves. The multiple temperature data are sorted by collection time.

[0087] Interference temperature data are removed from the multiple temperature data, and several analytical temperature data are determined. The interference temperature data include: continuous multiple constant temperature data, temperature data outside a preset range (T.sub.min, T.sub.max), as well as temperature data in 2 hours before opening, during opening and in 2 hours after closing of a back-drafting valve.

[0088] Moving average processing is performed on respective analytical temperature data in order according to the determination order of the several analytical temperature data. Specifically, a moving window with a preset step size of 2 minutes is created, and the moving interval of the moving window is 22 minutes, which means the moving window includes 11 temperature data. According to the set step size, starting from the first temperature data among the several analytical temperature data, forward moving processing is performed in the order of collection time until the last temperature data enters the moving window. After each time of moving, the average value of temperature data in the moving window is taken as the analytical temperature data of the 6.sup.th temperature collection point in the moving window, and several analytical temperature data T.sub.p are obtained after 5 times of moving.

[0089] The number of gas flow peaks is counted based on respective analytical temperature data T.sub.p subjected to the moving average processing. In the 5.sup.th to 9.sup.th sections of cooling staves, temperature data satisfying T.sub.p>T.sub.p1, T.sub.p>T.sub.p+1, and T.sub.p/T>1.05 is considered as a gas flow peak. In the 10.sup.th to 12.sup.th sections of cooling staves, temperature data satisfying T.sub.p>T.sub.p1, T.sub.p>T.sub.p+1, and T.sub.p/T>1.05 is considered as a gas flow peak. T.sub.p1, T.sub.p and T.sub.p+1 are the (p1).sup.th, p.sup.th and (p+1).sup.th analytical temperature data respectively, and T is the average temperature in unit time. The unit time is 1 h. The number of gas flow peaks of each section of cooling stave is the sum of the number of gas flow peaks counted at m thermocouples on that section of cooling stave in a day.

[0090] The temperature of each section of cooling stave is collected by the m thermocouples arranged on each section of cooling stave every 2 minutes. During the temperature collection process, a sample dataset is subjected to removal of outliers and removal of data under unstable working conditions and other interference temperature data to obtain a final processed sample dataset. The outliers include continuous multiple constant temperature data, and temperature data outside a preset range (T.sub.min, T.sub.max); and the data under unstable working conditions include temperature data in 2 hours before opening, during opening and in 2 hours after closing of a back-drafting valve.

[0091] The standard deviation of temperature of the k.sup.th cooling stave T.sub.k is calculated,

[00008]$T_k=\underset{j=1}{\overset{m}{.Math.}}\sqrt{\frac{1}{n-1}\underset{i=1}{\overset{n}{.Math.}}{\left(T_i-\stackrel{}{T}\right)}^2},$ [0092] where m is the number of temperature collection points on the k.sup.th cooling stave, j=1, . . . , m, T.sub.i is the i.sup.th temperature data of a temperature collection point on the k.sup.th cooling stave, n is the number of temperature samples in unit time, i=1, . . . , n, T is the average temperature in unit time, and the unit time is 1 hour.

[0093] The calculation formula for the heat load of the blast furnace TL.sub.i is TL.sub.i=c.Math.F(T.sub.outT.sub.in), where c is specific heat capacity of water, F is the flow rate of cooling water in the cooling stave 6, T.sub.out is the outlet water temperature of the cooling stave 6, and T.sub.in is the inlet water temperature of the cooling stave 6.

[0094] The standard deviation of heat load of the cooling stave 6, TL is calculated,

[00009]$\mathrm{TL}=\sqrt{\frac{1}{n-1}\underset{i=1}{\overset{n}{.Math.}}{\left({\mathrm{TL}}_i-\stackrel{\_}{\mathrm{TL}}\right)}^2},$ [0095] where TL.sub.i is the heat load of the blast furnace when the i.sup.th temperature data is collected, n is the number of heat load samples in unit time, i=1, . . . , n, and TL is the average heat load in 1 hour.

[0096] A correlation coefficient R.sub.k between a standard deviation of temperature T.sub.k of the k.sup.th cooling stave and a standard deviation of heat load of the blast furnace TL is calculated,

[00010]$R_k=\frac{\mathrm{Cov}\left(T_k,\mathrm{TL}\right)}{\sqrt{\mathrm{Var}\left(T_k\right).Math.\mathrm{Var}\left(\mathrm{TL}\right)}},$

[0097] Where Cov(T.sub.k, TL) is the sample covariance of T.sub.k and TL in several units of time within a preset time, Var(T.sub.k) is the variance of T.sub.k in several units of time within a preset time, Var(TL) is the variance of TL in several units of time within a preset time, the preset time is 24 hours, and the unit time is 1 hour.

[0098] The correlation coefficients R.sub.k of the 5.sup.th and 12.sup.th sections of cooling staves are counted respectively. The number of gas flow peaks of lower part of the blast furnace PD is the number of gas flow peaks of the section of cooling stave with the highest correlation coefficient R.sub.k in the 5.sup.th to 9.sup.th sections of cooling staves. The number of gas flow peaks of upper part of the blast furnace PU is the number of gas flow peaks of the section of cooling stave with the highest correlation coefficient R.sub.k in the 10.sup.th to 12.sup.th sections of cooling staves.

[0099] A database of blast furnace operating parameters is constructed, and the database includes the number of gas flow peaks of lower part of the blast furnace PD, the number of gas flow peaks of upper part of the blast furnace PU, blast furnace feed, a distribution system, an air supply system and a cooling system collected in production history.

[0100] Specifically, the blast furnace feed parameters include Zn content, alkali metal content and sintered fine ore percentage in the blast furnace feed. The distribution system parameters include the maximum tilting angle, charge level height and periphery load O/C. The air supply system includes tuyere area, tuyere length, blast volume and oxygen content. The cooling system includes the inlet water temperature and the flow rate of cooling water in the cooling stave 6.

[0101] The statistically obtained number of gas flow peaks of lower part of the blast furnace PD are divided into different grades in order of magnitude, to obtain the number of gas flow peaks of lower part of the blast furnace PD in 5 different ranges, and the average value of the blast furnace operating parameters in the same grade is taken, to obtain the database of blast furnace operating parameters as shown in Table 1.

TABLE-US-00001 TABLE 1 Flow rate of Charge Maximum Tuyere- Tuyere Blast Oxygen Sintered Alkali cooling Inlet water level tilting area/ length/ volume/ content/ fine Zn metals water temperature/ Grade PD PU O/C height/m angle/ m.sup.2 mm Nm.sup.3 Nm.sup.3/h ore/% (kg/t) (kg/t) (m.sup.3/h) C. 1 <2.85 14.9 1.98 1.4 46.2 0.546 630 7700 50000 23 0.08 2.6 6894 33.4 2 2.85-4.3 15.2 2.16 1.4 46.5 0.546 630 7750 48000 23 0.08 2.6 6884 34 3 4.3-5.7 13.9 2.36 1.4 46.4 0.546 630 7800 49000 22.97 0.08 2.6 6827 35 4 5.7-7.1 13.8 2.59 1.4 46.7 0.546 630 7770 48500 22.4 0.08 2.6 6906 34.6 5 >7.1 12.9 2.48 1.4 45.75 0.546 630 7790 48900 23 0.08 2.6 6781 36.1

[0102] In this embodiment, PD0 is 5.7, so the PD values in the 1.sup.st, 2.sup.nd and 3.sup.rd grades satisfy the first preset condition. Further, the blast furnace operating parameters with the lowest PU value in the 1.sup.st, 2.sup.nd and 3.sup.rd grades are selected, that is, the blast furnace operating parameters corresponding to the 3.sup.rd grade are selected to generate an instruction for setting the blast furnace operating parameters for the next operating stage, thereby effectively maintaining the stability of gas flow at the periphery of the blast furnace and achieving stable and smooth running of the blast furnace.

[0103] In summary, compared with the prior art, the method for controlling stability of gas flow at the periphery of a blast furnace of the present disclosure has the following beneficial effects: By calculating and counting the correlation coefficient R.sub.k between the standard deviation of temperature T.sub.k of each section of cooling stave and the standard deviation of heat load of the blast furnace TL, the upper cooling stave and lower cooling stave in the section that is most affected by temperature changes in the blast furnace can be respectively reflected. Further, the number of gas flow peaks of the section of cooling stave reflects the fluctuation of the gas flow at the periphery of the corresponding blast furnace. Further, based on the historical data of the number of gas flow peaks of lower part of the blast furnace PD and the number of gas flow peaks of upper part of the blast furnace PU, an optimal combination of blast furnace operating parameters is selected for the next operating stage of the blast furnace. Thus, targeted regulation of parameters that affect the gas flow at the inner periphery of the blast furnace can be performed to guide smooth running of the blast furnace and avoid abnormal blast furnace conditions caused by blindly setting the blast furnace operating parameters according to operator experience.

[0104] It should be understood that although the description is provided according to the implementations, not each implementation only includes one independent technical solution, and the narrative mode in the description is only for clarity. Those skilled in the art should consider the description as a whole, and the technical solutions in the implementations can also be appropriately combined to form other implementations that can be understood by those skilled in the art.

[0105] The series of detailed descriptions listed above are only specific illustrations for feasible implementations of the present disclosure, and are not intended to limit the scope of protection of the present disclosure. Any equivalent implementations or changes that do not depart from the craft and spirit of the present disclosure should be included in the scope of protection of the present disclosure.