RU2377322C2 - Control method of agglomeration process - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to ferrous metallurgy, and can be used at preparation of raw materials for blast melting, particularly for control of agglomeration process. Traverse speed of agglomerating trolley is regulated for providing of maximal value of relative yield of agglomerate not less than specified, anticipated value of which is defined by method of regression analysis relative to coupling. Coupling equation includes in the capacity of random quantity selected from massif of initial process parametres by method of correlation analysis significant process-dependent parametres during the last preset on-cycle of agglomachine. Period value is defined from the condition of receiving of normality of mentioned random quantities. Significant are assumed parametres, allowing coefficient of linear pair correlation with relative yield of agglomerate not less than 0.2, value of which is stipulated by that confidence level of value probability of relative yield of agglomerate was 95%.

EFFECT: method considers maximal number of parametres, reacting to mass of finished product, subject to adaptation to time of raw material properties and equipment with providing of maximal yield of agglomerate at its high grade.

2 cl, 1 dwg, 3 tbl

Description

The invention relates to ferrous metallurgy and can be used in the preparation of raw materials for blast furnace smelting, in particular for controlling the sintering process.

There is a known method of sintering sinter, in which two layers of sinter mixture of different thicknesses and with different contents of solid fuel and moisture are fed sequentially to moving sintering trolleys, after which the charge is ignited and vacuum is created under the sintering trolleys - see RU 2164252, С22В 1 / 16, 03.20.2001 / 1 /. In the process of sintering, the speed of the sintering carts is determined according to:

V = K * Q _wc * T _vs * W _ns * H _ns * P / T _ns * W _vs * H _vs * B,

where V is the speed of the sintering carts, m / min; Q _Жс is the consumption of the iron ore component of the charge, kg / t of sinter charge; T _sun , T _ns - solid fuel consumption, respectively, in the upper and lower layers,%; W _sun , W _ns - moisture content in the upper and lower layers, respectively,%; N _sun , N _ns - the thickness of the layers of the mixture, respectively, of the upper and lower, mm; P - vacuum under the sintering trolleys, mm of water. st .; In - the necessary basicity of the finished agglomerate, equal to 0.5-0.7, dimensionless; K is an empirical coefficient characterizing the sintering speed of the charge in both layers, equal to (8.5-80) * 10 ^-7 , m · t / min · kg (mm. Water. Art.), While the thickness of the lower layer of the charge is set to within 0.2-0.8 of the total thickness of the charge layer. As the iron ore component of the charge, sludge, a mixture of iron ore concentrates, sinter screening, and scale are used. The flow rate of each component is set, respectively, in the range of (0.05-0.13), (0.7-0.8), (0.11-0.12) and (0.03-0.065) of the consumption of the iron ore component of the charge.

A known method of controlling the agglomeration process disclosed in RU 2114190, C22B 1/20, 06/27/1998 / 2 /, in which the speed of movement of the sintering carts is determined, determined by the following relationship:

V = K * T * m * H * g / t * M * h * Q,

where V is the speed of the sintering carts, m / min; T is the content of iron ore concentrate in the mixture,%; t is the solid fuel content in the charge,%; M, m — solid fuel content in the charge, respectively, in the lower and upper layers,%; N, h - the thickness of the lower and upper layers of the mixture, mm; Q, g — moisture content in the charge, respectively, in the lower and upper layers,%; K is an empirical coefficient characterizing the sintering speed of the charge in both layers, equal to 0.1-0.2 m / min. The ratio of the mass of iron ore concentrate to the mass of solid fuel in the charge is maintained within 12-20.

As the closest analogue (prototype), a method for controlling the process of sintering the mixture on an sinter machine has been adopted, according to which the speed of the sintering carts is controlled taking into account the process parameters - see RU 2037540 C1, 06/19/1995 / 3 /. In this method, the mass of the concentrate produced is monitored at the end of the current shift, it is compared with a predetermined one, and the thickness of the charge layer on the sinter machine is established depending on the forecast deviation from the set value for the shift. The method is aimed at increasing the strength of the agglomerate when performing a scheduled task by the volume of its receipt.

The above methods for controlling the agglomeration process by calculating the speed of the sintering carts take into account a certain set of technological parameters that affect the agglomeration process. However, none of the above methods takes into account such important parameters as the temperature and pressure of the gases in the collector, the temperature in the last vacuum chambers, the temperature of the charge, the ignition temperature (in the hearth zones), etc. Therefore, to calculate the speed of the sintering carts, empirical coefficient having a wide range of changes (as, for example, in the method / 1 /), significantly limited flow ranges of each component of sinter charge are set. In addition, the above methods do not take into account the change in time of the condition of the equipment, characteristics of raw materials, etc.

An important characteristic for controlling the agglomeration process is the relative yield of the agglomerate, which is determined by the ratio of the sinter mass after screening (separation of suitable agglomerate) to the mass of the crude charge entering the sinter machine.

The objective of the invention is the creation of a process control method that takes into account the maximum number of parameters affecting the mass of finished products, taking into account the adaptation over time, the characteristics of raw materials and equipment.

The technical result obtained in solving this problem is to provide a given output of sinter, with its high quality, by controlling the speed of the sintering carts.

The technical result is achieved due to the fact that in the method of controlling the agglomeration process, in which the speed of the sintering carts is controlled taking into account the technological parameters of the process, the speed of the sintering carts is controlled to provide a given value of the relative yield of the sinter, the predicted value of which is determined by regression analysis using a communication equation, including random variables selected from an array of initial technological parameters by the method of correlation analysis, significant technological parameters of the process for the last, predetermined period of operation of the sinter machine, the value of which is determined from the conditions for obtaining the normal distribution law of the mentioned random values, while the speed of the sintering carts is changed if the predicted value of the relative yield of the sinter is less than specified.

To form an array of initial technological parameters, the following notation is used:

- относительный выход агломерата,

- relative yield of agglomerate,

where M _A is the mass of sinter agglomerate after screening, t / h; M _W - the mass of raw charge entering the agglomeration, t / h; x ₁ (B) - expense of own return, relative units; x ₂ (O) - domain return flow rate, relative units; x ₃ (K) - consumption of coke breeze, relative units; x ₄ (V) - the speed of the sintering carts, m / min; x ₅ (P _to ) - the gas pressure in the collector, mm of water. st .; x ₆ (T _to ) - gas temperature in the collector, ° C; x ₇ (W) - the moisture content of the mixture loaded onto the sinter machine,%; x ₈ (T _L-1 ) - temperature in the penultimate vacuum chamber, ° C; x ₉ (T _L ) - temperature in the last vacuum chamber, ° C; x ₁₀ (H) - pelletizer rotation speed, rpm; x ₁₁ (LR ₁ ) - consumption of concentrate 1, relative units; x ₁₂ (ЖР ₂ ) - consumption of concentrate 2, relative units; x ₁₃ (LR _N ) - flow rate of concentrate N, relative units.

The value of the relative yield of the finished agglomerate is determined taking into account the above notation according to the equation of communication:

y = A ₀ + A ₁ x ₁ + A ₂ x ₂ + A ₃ x ₃ + ... + A ₁₃ x ₁₃ , where A ₀ is a free term; A ₁ , A ₂ , A ₃ , ..., A ₁₃ are the coefficients of the communication equation.

The technological parameter of the process is considered significant if the coefficient of pair correlation between it and the relative yield of sinter is at least 0.2.

The proposed method for controlling the agglomeration process is based on a change in the speed of the sintering carts, determined in accordance with the calculation and taking into account all parameters that can directly or indirectly affect the relative yield of the agglomerate. In addition, the adaptation of parameters over time was introduced, since the state of the main technological equipment, the time of transport delay, and changes in the characteristics of raw materials are taken into account.

Figure 1 shows a block diagram showing the principle of operation of the control system.

In the input data input block 1, information on sinter charge characteristics and technological process parameters is introduced: self return flow rate, t / h (x ₁ ); domain return, t / h (x ₂ ); coke breeze, t / h (x ₃ ); iron ore concentrate 1, 2, N, t / h (x ₁₁ , x ₁₂ , x ₁₃ ); the mass of the mixture, t / h (M _W ); the speed of the sintering carts, m / min (x ₄ ); gas pressure in the collector, mm water. Art. (x ₅ ); the temperature of the gas in the collector, ° C (x ₆ ); the moisture content of the charge loaded on the sinter machine,% (x ₇ ); temperature in the penultimate vacuum chamber, ° C (x ₈ ); temperature in the last vacuum chamber, ° C (x ₉ ); pelletizer rotation speed, rpm (x ₁₀ ); mass of suitable agglomerate, t / h (M _a ). Next, in block 2, the costs of own return (x ₁ ), domain return (x ₂ ), coke breeze (x ₃ ), iron ore concentrate 1 (x ₁₁ ), 2 (x ₁₂ ), N (x ₁₃ ) are calculated in relative units. Then, in block 3, the yield of the sinter, in relative units (y), is calculated by dividing the mass of suitable sinter by the mass of the charge fed to the sinter machine. The sinter yield is calculated taking into account the transport lag between the time of the charge entering the sinter machine and the time of receipt of the finished sinter. In block 4, a matrix of technological parameters is formed. In block 5, the calculation and ranking of linear pair correlation coefficients in descending order is performed. The following matrix is compiled - block 6, which includes significant parameters. Based on the data of the matrix of significant parameters in block 7, the calculation of the communication equation is performed. In block 8, the predicted value of the sinter yield is calculated. In block 9, the forecast and set value of the sinter yield are compared and, if the predicted value of the sinter output is greater than or equal to the set value, then all previous information processing continues. If the predicted value is less than the specified value, then the speed of the sintering carts is changed so that the relative yield of the sinter is not less than the specified value. The new value of the speed of movement of the sintering trolleys is calculated according to the coupling equation into which the set value of the relative output of the sinter is substituted. The speed control of the sintering trolleys is performed in block 12.

The technical effect when implementing the method is to provide such a speed of movement of the sintering trolleys at which the relative output of the sinter will be no less than a given one. For this, all measured parameters of the sinter charge and technological operating conditions of the sinter machine (hourly values) are recorded, for the last hours of operation, taking into account the time of transport delay.

The value of the period of operation during which the measured parameters and technological modes are fixed is taken so that the law of distribution of a random variable (technological parameter) is normal. As the practice of such calculations has shown, usually with sixty values of each parameter, the distribution law of its value becomes normal. Moreover, information on the operation of the sinter machine is updated hourly, which ensures adaptation of the obtained analysis results over time.

The method and correlation analysis select the parameters and characteristics of the technological process that affect the value of the relative yield of sinter (significant parameters). The linear pair correlation coefficient is determined by the formula [1]:

- среднее значение аргумента; у - текущее значение функции;

- среднее значение функции. Коэффициенты корреляции рассчитывают между относительным выходом агломерата (у) и каждым параметромwhere x is the current value of the argument;

- the average value of the argument; y is the current value of the function;

- the average value of the function. Correlation coefficients are calculated between the relative sinter yield (y) and each parameter

(x ₁ , x ₂ , x ₃ , ..., x ₁₃ ). Parameters (matrix columns) having correlation coefficients less than 0.2 are excluded from the primary matrix as insignificant. The established value of the correlation coefficient is due to the confidence level of the probability of the relative yield being 95%.

The resulting secondary matrix of significant technological parameters is used to calculate the communication equation, having the form:

y = A ₀ + A ₁ · x ₁ + A ₂ · x ₂ + A ₃ · x ₃ + ... + A ₁₃ · x ₁₃ ,

where A ₀ is a free member;

A ₁ , A ₂ , ..., And _n are the coefficients of the coupling equation;

x ₁ , x _2, ..., x _n are the arguments of the coupling equation.

The values of the coefficients of the coupling equation are found [2] from the solution of the system of normal equations by the least squares method. First of all, all dependency variables are expressed on a standardized scale using transition formulas

where y is the value of the function;

σ _y is the mean square deviation of the function,

where x _i is the value of the argument (parameter) in natural scale;

- среднее значение аргумента (параметра);

- the average value of the argument (parameter);

t _xI - parameter value in a standardized scale.

The communication equation in a standardized scale will look like:

t = β ₁ · t _x1 + β ₂ · t _x2 + ... + β ₁₃ · t ₁₃ ,

where t _x1 , t _x2 , ..., t _x13 are the standardized values of the variables x ₁ , x ₂ , ..., x ₁₃ ;

β ₁ , β ₂ , ..., β ₁₃ - standardized coefficients of multiple regression.

A ₀ b ₀ = 0.

Using the least squares method, we examine the minimum function:

We write a system of equations for determining the parameters of the dependence of y on x ₁ , x ₂ , ..., x ₁₃

r _yx1 = b ₁ + r _x1x2 b ₂ + r _x1x3 b ₃ + ... + r _x1x13 b ₁₃ ,

r _yx2 = r _x2x1 b ₁ + b ₂ + r _x2x3 b ₃ + ... + r _x2x13 b ₁₃ ,

r _yx3 = r _x3x1 b ₁ + r _x3x2 b ₂ + b ₃ + ... + r _x3x13 b ₁₃ ,

• • • • • • • • • • • •

r _yx13 = r _x13x1 b ₁ + r _x13x2 b ₂ + r _x13x3 b ₃ + ... + b ₁₃ ,

where r _yx1 , r _yx2 , r _x1x2 , ..., r _x12x13 are the corresponding linear pair correlation coefficients.

From the above system of equations we find b ₁ , b ₂ , b ₃ , ..., b ₁₃ .

where Δ is the main determinant;

Δ _i is the complement of the determinant in i.

The calculated relative yield of agglomerate is used as a predicted value. If the predicted value of the output of the sinter is less than the specified, regulate the speed of the sintering carts.

An analysis of the operation of the sinter machine shows that over time, the coefficients of the parameters affecting the relative yield of the sinter change, a different kind of dependence becomes possible, in addition, the parameters affecting the relative yield of the sinter can disappear from the coupling equation and other parameters may appear instead. Thus, the coupling equation can be modified.

The calculations of the dependences of the relative sinter yield performed for the AKM-312 sinter machine of OJSC Severstal at various periods of its operation confirmed this. The results are shown in the tables.

So, for example, in the first period (Table 1), the coupling equation has the form

y = -0.203 + 0.00295x ₈ + 0.00565x ₉ -0.004x ₆ -0.00054x ₅ -0.0385x ₄ -2.67x ₁₃ .

In the second period (Table 2), the coupling equation has the form

y = 0.57 + 0.015x ₈ + 0.0014x ₉ -0.072x ₄ -0.0005x ₆ -0.00038x ₅ .

In the third period (table 3)

y = 0.17-0.0036x ₁ -0.0034x ₂ + 0.415x ₃ -0.083x ₄ -0.0001x ₅ .

In the above examples, both the form of the dependence and the significant parameters of the coupling equation change.

Claims (2)

1. The method of controlling the agglomeration process, including controlling the speed of the sintering carts taking into account the technological parameters of the process, characterized in that the speed of the sintering carts is controlled to ensure the greatest value of the relative output of the sinter is not less than the specified value, the predicted value of which is determined by regression analysis according to the communication equation, including as random variables selected from an array of initial technological parameters by the correlation method analysis of significant technological process parameters for the last pre-set sinter machine operation period, the value of which is determined from the conditions for obtaining the normal distribution law of the mentioned random variables, the parameters having a linear pair correlation coefficient with a relative sinter output of at least 0.2, the value of which is caused by so that the confidence level of probability of the relative yield of the agglomerate is 95%. 2. The method according to claim 1, characterized in that the following parameters are used to form an array of initial technological parameters:
B - expense of own return, relative units,
О - domain return flow rate, relative units,
K is the consumption of coke breeze, relative units,
V is the speed of the sintering carts, m / min,
R _{to the} gas pressure in the collector, mm vod.st,
T _to - the temperature of the gas in the collector, ° C,
W is the moisture content of the mixture loaded onto the sinter machine,%,
T _L-1 - temperature in the penultimate vacuum chamber, ° C,
T _L is the temperature in the last vacuum chamber, ° C,
N - pelletizer rotation speed, rpm,
ЖР ₁ - consumption of concentrate 1, relative units,
ЖР ₂ - consumption of concentrate 2, relative units,
ЖР _N - concentrate N consumption, relative units.

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