RU2037540C1 - Method to control charge sintering process in sintering machine - Google Patents

Abstract

FIELD: metallurgy. SUBSTANCE: method to control charge sintering process in sintering machine provides for control of produced agglomerate mass and stabilization of sintering zone position by changing speed of sintering machine grate position. Value of produced agglomerate mass at the end of running shift is periodically determined and thickness of charge layer in sintering machine is set depending on forecasting deviation of agglomerate mass from its given value for the shift. Method provides production of agglomerate at the level of plan task and increase of agglomerate strength due to sintering of charge in higher layer. EFFECT: method to control charge sintering process in sintering machine is used in metallurgy. 1 dwg

Description

 The invention relates to the preparation of ores and can be used to control the sinter process.

 One of the most important tasks in sinter production is to improve the quality of the sinter, in particular its strength. The strength of the agglomerate increases with increasing thermal level of the process and the duration of sintering of the mixture.

 The most economical way to increase the heat level is to sinter the mixture in a higher layer.

 A known method of controlling the process of sintering a charge on an sinter machine [1] consisting in determining the position of the fuel combustion zone in the charge layer and stabilizing the position of this zone at the end of the sinter by changing the thickness of the charge layer and the speed of the belt.

 However, the use of the charge layer thickness to stabilize the position of the combustion zone is impractical. This method does not improve the quality of the agglomerate.

 A known method of regulating the sintering process of the charge [2] consisting in changing the speed of movement of the sinter depending on the height of the layer of sinter.

 This solution does not provide stabilization of the position of the end point of the sintering of the mixture and improve the quality of the sinter.

 The prototype of the proposed method is a method for controlling the agglomeration process [3], which includes control of the heat quality, gas permeability of the charge layer and the quality of the agglomerate, and control of fuel consumption, sinter speed and thickness of the charge layer based on the initially established equations.

 The disadvantage of this method is that it does not provide an increase in the quality of the sinter with a potential excess of sinter production compared to a predetermined value.

 The aim of the proposed method is to increase the strength of the agglomerate.

где Н_ш.о.,Н_ш исходное и устанавливаемое значение толщины слоя шихты, мм;
М_а.з. заданное на смену значение массы агломерата, т;
М_а.пр. М_а.о. + М_а.ч. (t_см. t_o) прогнозируемое на конец смены значение массы агломерата, т;
М_а.о. масса агломерата, произведенного от начала смены, т;
М_а.ч. масса агломерата, произведенного за истекший период, т;
t_см длительность смены;
t_о время, прошедшее от начала смены, ч;
К коэффициент пропорциональности, устанавливаемый на основании опытных данных, мм/(т/ч).This is achieved by the fact that periodically, for example, every hour, the mass value of the sinter produced is predicted at the end of the current shift, and the thickness of the charge layer on the sinter machine is set depending on the predicted deviation of the mass of the sinter from its specified change value by the formula
H _W = H _W.- K

where H _Sh.O. , N _{W the} initial and set value of the thickness of the layer of the charge, mm;
M _a.s. the given value to change the mass of the sinter, t;
M _a.s. M _a.o. + M _A.Ch. (t _see t _o ) predicted at the end of the shift the value of the mass of the sinter, t;
M _a.o. mass of agglomerate produced from the start of the shift, t;
M _A.Ch. mass of sinter produced over the past period, t;
t _cm shift duration;
t _{about the} time elapsed from the start of the shift, h;
To the coefficient of proportionality, established on the basis of experimental data, mm / (t / h).

 An increase in the thickness of the layer of sintered mixture provides an increase in the strength of the agglomerate and a decrease in the content of fine fractions of 5-0 mm in it due to a more complete use of regenerated heat.

With an increase in the thickness of the charge layer to 500 mm, the coke consumption for sintering decreased by 12%; the content of the 5-0 mm fraction in the agglomerate decreased by 13.5% after testing in the drum. An increase in the layer thickness from 270 to 570 mm reduced the yield of return by 30%
The drawing shows the dependence of the strength of the agglomerate on the thickness of the layer.

 The possibility of a significant increase in the layer thickness is limited by the fact that this reduces the sintering speed of the mixture and the performance of the sinter machine. The decrease in sintering speed is due to an increase in the gas-dynamic resistance of the sintered layer.

 The drawing shows the dependence of the sintering speed on the thickness of the layer during sintering of sinter ore and concentrate with limestone (curve 1) and with the replacement of part of limestone with lime (curve 2).

 Under production conditions, the solution to the question of the optimal layer thickness is a compromise, providing a combination of acceptable sintering speed and sinter strength.

 The essence of the proposed method is to ensure the production of sinter at the level of the plan, as well as to improve the quality of the sinter with a predicted excess of sinter production relative to the task.

The forecast of the mass of the sinter, which can be produced on the sinter machine by the end of the current shift, is carried out periodically, for example, every hour. The predicted mass of agglomerate M _a.pr. it is determined under the assumption that the performance of the sinter machine from the current moment to the end of the shift will remain unchanged and equal to its productivity over the expired control period (hereinafter, for concreteness, over the past hour):
M _a.s. M _a.o. + M _a.h. (t _see t _o ), (1) where M _a.o. mass of sinter produced at the moment from the start of the shift;
M _A.Ch. mass of sinter produced in the last hour;
t _see total shift duration;
t _{about the} time elapsed from the start of the shift.

The basis for the implementation of the control action is the predicted deviation of the mass of the sinter from its predetermined change value
ΔM _a.s. M _a.s. M _a.s. , (2) where M _a.s.

The change in the productivity of the sinter machine, necessary to ensure the planned task, depends on the predicted deviation of the mass of the sinter and the time remaining until the end of the shift,
ΔQ _a.s. Q _a.s. Q _a.o. ΔM _a.s. (t _see t _o ), (3) where Q _a.o. initial value of sinter machine productivity;
Q _a.s. new sinter machine productivity value set under control action.

The influence of the thickness of the charge layer on the performance of the sinter machine as a whole is expressed by a nonlinear function, but within a limited range of changes in the thickness of the layer, this dependence is approximated with a sufficient approximation by a linear characteristic of the form
Q _a Q _a.o. K _n ˙ΔN _w. , (4) where Q _a.o. , Q _{and the} initial and final value of the productivity of the sinter machine, t / h;
To _n. a coefficient characterizing the effect of the thickness of the charge layer on the performance of the sinter machine, (t / h) / mm;
ΔN _sh. change in the thickness of the charge layer, mm

(0,1-0,25)%/мм
(5) где ΔQ_а* относительное изменение производительности агломашины,
В удельном выражении данный коэффициент равен
K_н.уд=

(1,7÷4,2)·10

(6) где Q_а.уд. удельная (отнесенная к площади спекания) производительность агломашины в среднем 1,7 (т/ч)/м².Studies of the agglomeration process found that the coefficient characterizing the percentage influence of the thickness of the charge layer on the performance of the sinter machine is
K $\genfrac{}{}{0ex}{}{\text{*}}{\text{n}}$

(0.1-0.25)% / mm
(5) where ΔQ _a * is the relative change in sinter productivity,
In specific terms, this coefficient is
K _n.ud =

(1.7 ÷ 4.2) · 10

(6) where Q _a.aud. specific (referred to the sintering area) sinter productivity on average 1.7 (t / h) / m ² .

K_н.уд·S_сп
(7)
Например, для агломашины с площадью спекания S_сп. 312 м²
К_н. (0,53 1,32) (т/ч)/мм
В соответствии с линеаризованной характеристикой (4) управляющее воздействие по данному способу формируется по уравнению
H_ш= H_ш.о-K

(8) где Н_ш.о., Н_ш. исходное и устанавливаемое заданные значения толщины слоя шихты, мм;
K

где К коэффициент пропорциональности мм/(т/ч).For sinter machines with sintering area S _sp. coefficient K _n . is equal to
K _n

K _n.ud · S _cn
(7)
For example, for sinter machines with sintering area S _sp. 312 m ²
To _n. (0.53 1.32) (t / h) / mm
In accordance with the linearized characteristic (4), the control action by this method is formed according to the equation
H _W = H _W.- K

(8) where H _Sh.O. , N _sh. initial and set target values of the thickness of the charge layer, mm;
K

where K is the coefficient of proportionality mm / (t / h).

For sinter machines with S _sp. 312 m ² K (0.75 -1.9) mm / (t / h).

When implementing this method, the magnitude of the change in layer thickness is limited to a minimum of N _Sh.min and a maximum of N _Sh.max. permissible values established on the basis of technological requirements.

(0,08÷0,12)%/мм
(9) где Δq_{( > 8)} изменение содержания в агломерате фракций крупностью больше 8 мм после испытаний в барабане.The influence of the layer thickness on the strength of the agglomerate according to the research results is characterized by a coefficient
_{K, etc.} =

(0.08 ÷ 0.12)% / mm
(9) where Δq _{( > 8) is a} change in the content in the sinter of fractions with a particle size greater than 8 mm after testing in a drum.

With limited changes in the layer thickness, the strength of the agglomerate changes as
q _{(> 8)} q _{(> 8) .o} + K _{so on.} + ΔН _sh. (10)
Thus, when controlling the sintering process according to the proposed method, the planned task for the production of sinter is ensured, and in cases of a potentially possible excess of production over the task, a possible improvement in the quality of the sinter is realized.

Example of using the proposed method for controlling the sintering process of a charge on an AKM-312 sinter machine with a sintering area S _sp. = 312 m ² .

Initial parameters and settings:
_Tailored production of sinter M _a.z. 4000 t;
the initial value of the thickness of the layer of the charge N _W 300 mm;
initial value of a drum sample of agglomerate q _{(> 8) o} 45%
total shift duration t _cm 8 h;
time elapsed from the start of the shift, t _o 3 h;
mass of sinter produced from the start of the shift, M _a.o. 2000 t;
Current time sinter production M _TH 500 t;
permissible boundary values of the thickness of the layer of the charge N _W.min. 300 mm, N _{W. max.} 450 mm;
the coefficients of the influence of the thickness of the layer on the performance of the sinter machine and on the strength of the sinter installed initially, K _n 1.25 (t / h) / mm, K _etc. 0.1 / mm.

The agglomerate mass predicted at the end of the shift in accordance with equation (1) is
M _a.s. 2000 + 500 (8-3) 4500 t
The predicted deviation of the mass of the agglomerate from the set value according to equation (2) is
Δ M _a.s. 4000 4500 -500 t
A suitable change in the performance of the sinter machine according to equation (3) is equal to
ΔQ _a.s. -500 / (8-3) -100 t / h.

380 мм
При установлении данной толщины слоя производительность агломашины станет равной
Q_а 500 100 400 т/ч, и к концу смены будет произведена масса агломерата
М_см. 2000 + 400˙5 4000 т следовательно, будет обеспечено выполнение планового задания.Based on equation (8) for the indicated change in productivity, the new value of the thickness of the charge layer should be taken equal to
H _w = 300+

380 mm
When this layer thickness is established, the performance of the sinter machine will become equal
Q _a 500 100 400 t / h, and by the end of the shift a mass of sinter will be produced
M _see 2000 + 400˙5 4000 t therefore, the fulfillment of the planned task will be ensured.

Due to the sintering of the charge in a higher layer, the strength of the sinter produced during the time from the moment of the control action to the end of the shift will increase. In accordance with equation (10) the drum sample of the agglomerate will be
q _{(> 8)} 45 + 0.1˙80 53% i.e. agglomerate strength compared with the original increase by 17.8%
PRI me R implementation of the method. To implement the proposed method, an automated process control system for process control systems can be used, which includes sensors of controlled parameters, a computing device, and executive bodies. Currently, this process control system operates on sinter machine No. 4 of the Novolipetsk Steel, where it controls the processes of pelletizing, loading, ignition and sintering of the charge. The system automatically controls the technological parameters (including the mass of the sinter being shipped), as well as stabilizes such parameters as the charge consumption on the sinter machine, the moisture content of the charge, the thickness of the charge layer on the sinter, the ignition temperature of the charge and the coordinate of the end point of sintering of the charge.

 The function corresponding to the proposed method is programmed in the computing device and is currently undergoing testing and debugging.

The implementation of this function is as follows. Periodically (in this case, every 2 hours), the agglomerate mass value predicted at the end of the shift and the appropriate new layer thickness value are determined in the computing device. The new value of the layer thickness is limited by the permissible limits of N _W.min. N _max . and is introduced as a task in the program loop stabilization of the thickness of the layer of the mixture, which is further supported by influencing the speed of rotation of the feed mixture.

 At the cycle time indicated above, this function is performed four times during a shift. Therefore, during the shift, the system can flexibly respond to changes in the initial physical and chemical properties of the charge materials and changes in sintering conditions, which affect the performance of the sinter machine and the quality of the sinter.

The system is focused on ensuring the fulfillment of the task for the production of sinter. Limiting the change in the thickness of the layer to a minimum value of N _W.min. eliminates the possibility of reducing the strength of the agglomerate below the permissible limit. If there is a potential possibility of overproduction of sinter relative to a given value, the system by a corresponding increase in the layer thickness provides a predetermined mass value of the produced sinter. In this case, the quality (strength) of the produced sinter is increased.

Claims (1)

METHOD FOR MANAGING THE SINTERING OF THE BATCH ON THE AGLOMACHINE, including controlling the mass of the sinter being produced and stabilizing the position of the sintering zone by changing the speed of the sinter, characterized in that the mass of the sinter produced at the end of the set time periodically is determined and the thickness of the charge layer is set in the sinter machine from the deviation of the predicted mass of the agglomerate from its specified value for the specified time interval according to the mathematical expression:

where H _{w. about} , H _{W the} initial and set value of the thickness of the layer of the mixture, mm;
M _{a . h} set for a given time interval the mass value of the sinter, t;
M _{a . p r} M _{a . 0} + M _{a . h} (t _{with m} t ₀ ) the agglomerate mass value predicted at the end of a given time interval, t;
M _{a . 0} mass of agglomerate produced from the beginning of a given time interval, t;
M _{a . h the} mass of sinter produced over the past period, t;
t _{s m the} duration of a given time interval, h;
t _{0 the} time elapsed from the beginning of the specified time interval, h;
K coefficient of proportionality, mm / t / t.

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