RU2062656C1 - Method of controlling grinding process in rattler - Google Patents

Abstract

FIELD: metallurgy, chemical engineering. SUBSTANCE: method of controlling the grinding process in rattler lies in the fact that the step value of level change of rattler filling ΔΦ determined by extremal regulator is corrected depending on difference in values of current power of rattler drive P/t/ and base power P^x which is defined depending on fixation number of indication of overload mode for definite period of time τ. Thus the possibility of controlling the system stability margin, of providing for definite, optimal under given production-economic conditions probability of overload mode approach is achieved. EFFECT: enhanced quality of fine grinding of materials, enhanced efficiency of extremal regulation.

Description

 The invention relates to the automation of processes for grinding raw materials in drum mills and can be used in metallurgical, chemical, cement and other industries related to the processes of fine grinding of materials.

 There is a method of controlling the loading of a drum mill, which consists in the extreme regulation of its productivity, fixing emergency overloads and eliminating them by temporarily eliminating extreme regulation and implementing a certain effect in the direction of reducing material consumption, determining, after exposure to material consumption after a transition process has elapsed, increment of the mill loading level , exceeds the established norm, increasing the accepted value of the impact on the consumption of material and repeating it with the extreme regulation excluded, and in the case when the increment of the mill loading level does not exceed the established one: norms, introducing extreme regulation, determining the time interval during which the extreme regulation is carried out in the same direction, corresponding to an increase in material consumption, and if this is exceeded the time interval of the established norm of reducing the accepted value of the impact on the consumption of material in the mill [1] In this method, there is no possibility l control the stability margin of the regulatory system.

 The aim of the invention is to increase the stability and efficiency of extreme regulation.

This is achieved by the fact that the step ΔΦ of the change in the mill filling level, determined by the extreme controller, is adjusted depending on the difference between the values of the current mill drive power P (t) and the base P ^x , which is determined depending on the number of n-fixations of the overload mode to a certain previous period t and corresponds to a certain probability of the occurrence of an overload mode, optimal in the given production and economic conditions.

Если текущая мощность Р(t) близка к базовому значению Р^x,

, то нет оснований для корректировки работы экстремального регулятора.The invention consists in the following. It is known that the probability of the occurrence of an overload mode depends on the degree of filling of the mill v and the power of the drive R. With the growth of these parameters, the probability of the occurrence of an overload increases, but it is difficult to establish this dependence in an analytical form due to the drift of the static characteristic P = f (Φ), as well as zero drift of the received signals. The probability of an overload mode occurrence is manifested in the frequency of the overload mode occurrence; it can be estimated statistically by the number n of fixations of the onset of the overload mode attribute in a certain time interval τ preceding the current moment. For specific industrial and economic conditions, there is an optimal probability of the occurrence of an overload mode: maintaining a lower probability is associated with a deviation of the filling level v of the mill from the optimal value downward, which is accompanied by productivity losses. Maintaining conditions of increased likelihood of an overload occurrence also leads to a loss of productivity due to the frequent occurrence of an overload and taking measures to eliminate it. The basic value of the power P ^x corresponds to the optimal value of the probability of the occurrence of an overload and varies in accordance with changes in the grinding conditions - the properties of the feedstock, its grain size and wear of the lining of the grinding unit; the basic power value is estimated discretely through each time interval t, during which the current value of the probability of occurrence of the overload mode is estimated:

If the current power P (t) is close to the base value of P ^x ,

, then there is no reason to adjust the operation of the extreme regulator.

и, следовательно, вероятность наступления перегрузки становится больше приемлемой величины, то целесообразна корректировка величины шага Dv, определенной экстремальным регулятором ΔΦ^*= k•ΔΦ,, где ΔΦ^* скорректированное значение поискового шага экстремального регулятора.If the current power P (t) is significantly greater than the base value

and, therefore, the probability of the occurrence of an overload becomes more than an acceptable value, then it is advisable to adjust the value of the step Dv determined by the extreme regulator ΔΦ ^* = k • ΔΦ ,, where ΔΦ ^{* is the} adjusted value of the search step of the extreme regulator.

 In this case, the value of the coefficient K should change depending on the sign of Dv: if Dv> 0 (i.e., a step is taken to increase the level of filling Φ under conditions of an already increased probability of an overload), then this step should be adjusted downward, those. K <1 if Dv <0 (i.e., a step is taken towards lowering the level of filling Φ, then it is advisable to increase such a step (K> 1), which leads to an accelerated decrease in the probability of an overload.

, где ΔP предельно допустимое отклонение, определяемое на основе статистических данных так, чтобы ΔP ≥ P(t)-P $\genfrac{}{}{0ex}{}{\text{*}}{\text{o}}$ .The ratio satisfies these requirements:

, where ΔP is the maximum permissible deviation determined on the basis of statistical data so that ΔP ≥ P (t) -P $\genfrac{}{}{0ex}{}{\text{*}}{\text{o}}$ .

If P (t) <P $\genfrac{}{}{0ex}{}{\text{*}}{\text{o}}$ and, therefore, the probability of an overload occurring is less than optimal, then relation (1) ensures that the correction is carried out in the opposite direction.

The values of the time interval τ, the parameters a, ΔP, n ₁ , n ₂ ,, as well as the initial value of the base power P $\genfrac{}{}{0ex}{}{\text{*}}{\text{o}}$ determined in advance, based on a feasibility study taking into account statistical data. An adequate choice of these parameters makes it possible to control the margin of stability of the system, to ensure a certain probability of overload occurrence, which is optimal in the given production and economic conditions, which increases the efficiency of the extreme mill productivity controller.

 The method is implemented when controlling the grinding unit using control computer technology.

Claims (1)

A method of controlling the grinding process in a drum mill, which consists in measuring the drive power P (t) and the drum filling level Φ (t), extreme regulation of mill productivity, fixing emergency overloads, temporarily eliminating extreme regulation, reducing material consumption, loading analysis at the end of the transition process and in the case of overload there is an additional reinforced reduction in material consumption with extreme regulation excluded, and in the absence of overload reuse the application of extreme regulation, the determination of the period of time during which the extreme regulation is carried out in the same direction, corresponding to an increase in the load level and if this period of time exceeds the established rate of increase in material consumption, characterized in that the value τ of the time interval for estimating the probability of an overload occurrence is selected for every next jth interval, the number n _{j of} occurrences of the overload sign is counted, the base value of the drive power P is determined $\genfrac{}{}{0ex}{}{\text{*}}{\text{j}}$ after each j-th time interval in accordance with the ratio:

and the magnitude of the working step of extreme regulation is adjusted by the expression:

where p $\genfrac{}{}{0ex}{}{\text{*}}{\text{j}}$ , P $\genfrac{}{}{0ex}{}{\text{*}}{\text{j-1}}$ values of the base power, respectively, for the jth and previous j-1 intervals of duration P $\genfrac{}{}{0ex}{}{\text{*}}{\text{o}}$ ;
τ initial value of the base power;
and a given amount of change in the base power depending on the value of n _j ;
n ₁ and n ₂ predetermined threshold values of n _j ;
ΔΦ ^* adjusted value of the working step of the extreme controller;
DP is the maximum permissible deviation given in compliance with the inequality,
ΔP≥ P (t) -P $\genfrac{}{}{0ex}{}{\text{*}}{\text{j}}$ for all j.