JPS63206434A - Moisture control method for sintered raw materials - Google Patents

Abstract

PURPOSE:To improve control accuracy of the aimed moisture by summing up the necessary adding water quantities calculated respectively a feedforward control system by predicting value and feedback control system by actual measured value. CONSTITUTION:The aimed value of moisture in the raw material after adding water is predicted to divide and the aimed values in the feedforward control system and the feedback control system are respectively obtd. In the feedforward control system, the moisture in the raw material before adding water calculated based on each actual measured value of added water quantity, the moisture in the raw material after adding water and transported quantity of the raw material before adding water, is predicted and the necessary adding water quantity is calculated by using the above predicting value. On the other hand, in the feedback control system, by using a value correcting the actual measured value of the moisture in the raw material after adding water in accordance with the above aimed value and using an equation containing coefficient corrected in accordance with variation of the moisture in the raw material and the transported quantity of the raw material, the necessary adding water quantity is calculated. The moisture control is executed by the sum-up value of each necessary adding water quantity respectively for both these control systems as the adding water quantity to a sintering raw material.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a method for controlling moisture in sintered raw materials.

Conventional technology In the sintering process in the steel industry, sintering raw materials such as ore powder, limestone, and coke powder are mixed in a mixer, water is added to maintain a constant moisture content, and the materials are fed to a sintering machine where they are sintered. It becomes condensation. In this sintering process, the moisture content of the sintering raw material is an important factor for stabilizing the productivity and quality of the sintered ore (sintered ore particle size, sintered ore reduction powdering rate, etc.). As a method of controlling to the target value,
Publication No. 50-20528, Special Publication No. 60-
A method described in Japanese Patent No. 22051 and the like has been proposed.

FIG. 3 is a diagram showing the method described in Japanese Patent Publication No. 47-9035, in which W1 to W4 are raw material hoppers;
01 is a cutting conveyor, C2 is a charging conveyor, 03 is a transfer conveyor, M is a mixer, H is a hopper,
31 is a moisture meter, 33-1.33-2 is an arithmetic controller, 34
-1.34-2 is a flow rate regulator Kanakura water sprinkler, and 35 is a delay circuit.

The control method shown in Fig. 3 is a method that combines feed forward control using the predicted or measured value of the moisture content of the raw material before adding water and feedback control using the measured value of the raw material moisture after adding water. The water sprinkling system for the reeds and mixer is divided into two stages: front and rear, and the first stage increases the weight of the amount of added water based on feed forward control to prevent hanging, and the second stage adds water based on fee F/puncture control. The water amount weighter is increased to enhance the correction effect.

Problems to be Solved by the InventionAlthough the above-mentioned conventional methods can control moisture content to some extent, the control accuracy is still insufficient due to the following points. In other words, ■The moisture content of the raw material before water addition, which is used to calculate the amount of water added to the mixer, actually fluctuates from moment to moment; however, in the conventional method, the predicted moisture content of the raw material before water addition is used instead of the actually measured moisture content of the raw material before water addition. Since the control was carried out by regarding the value as a constant value over a long period of time, the control accuracy to the target moisture content was sufficient. ■A relatively simple formula is used to calculate the amount of water added to the mixer, and each coefficient included in this formula is based on a value determined empirically in advance, based on changes in the amount of raw material transported and moisture content. However, since the fcfc was used for a long time without modification, the accuracy of controlling the target moisture content was insufficient.

In view of the above-mentioned points, an object of the present invention is to provide a sintering raw material moisture control method that further improves the control accuracy of target moisture.

Means for Solving the Problem The method of the present invention to achieve this object is a method for controlling raw material moisture in a sintering process in which the amount of water added to the sintering raw material is completely controlled so that the raw material moisture reaches a target value. The entire control system is configured by combining a feed forward control system based on the moisture content of the raw material before water addition and a feed forward control system based on the moisture content of the raw material after water addition. The subsequent target value of raw material moisture is virtually divided into the target value of the feed-forward control system and the target value of the feed-back control system using a certain division ratio. The required amount of added water for the feed forward control system is calculated using the predicted value of the raw material moisture before water addition, which is calculated from moment to moment based on the raw material moisture and each actual measured value of the raw material transport amount before water addition. In the back control system, the actual measured raw material moisture content after water addition is
Using a value corrected according to the target value of the pack control system, and using a formula for calculating the amount of added water that includes a coefficient that is corrected according to fluctuations in raw material moisture and raw material transportation amount, the required amount of added water for the feedback control system is determined. A sintering raw material characterized in that the amount of water added to the sintering raw material is determined by calculating the amount of water required for the feed forward control system and the amount of water added for the feed forward control system. This is a moisture control method.

action The present invention will be explained in detail below.

In the moisture control process of the sintered raw material, the raw material moisture ai before water addition, the amount of added water Uw (ton/hr), the raw material moisture FLo after water addition, and the raw material transport amount Ui (to
There is the following relationship between n/hr and J.

Ui+Uw This equation (1) is used in the feed number forward control system of the present invention to predict the raw material moisture content before adding water from other measured values and to calculate the amount of water to be added based on this predicted value.

Further, the equation describing the material balance in the mixer is shown in the following equation, and the equation describing the moisture balance is shown in Table 1 below.

Here, [; Time x; Water addition position in the mixer (mJ Dl; Raw material backflow coefficient (m+ W; Raw material type of unit length at position X, Jl (t on
7m) Raw material transport lid tQn/br at U word position X
) UH; amount of water added per unit length at position X (ton/h
r@mJ R: Raw material moisture D2 at position
) and (3) are too complicated to be used for actual control, so the following equation is used as an approximate equation.

1iV −= U・+U−U−−−−−・−−−−−−−−−
(4) dt j w O−“ − where W; Weight of raw materials in the watering snog (ton) α
: Coefficient β of 0 × α × 1; Coefficient of 0 × β × 1 01 Time conversion coefficient < hr) Uo: Amount of raw material transported after water addition (ton/brl Equations (4), (5), and (6) The meanings of the equations are that Equation (4) represents the material balance, Equation (5) represents the water flow rate, and Equation (6) represents the average value of the raw material water content in the water sprinkler.

The left side of equation (4) is set to O because it is minute as a control system.

Note that the above equations (4), (5), and (6) are equations when the water sprinkling span in the mixer is short (when the water sprinkling system is one stage), and when the water sprinkling span is long ( (If the watering system is multistage), use equations (4), (5), and (6).
An approximate equation of the required order can be obtained by using the input-output relationship in the equation.

In equations (5) and (6), the transport delay time L (hrJ
f.

Taking this into account and summarizing it into the state equation of control theory, the following system of equations is obtained.

2×1 matrix-8...(8-17 to 1=β/[(1-β] ・θ)] ・ ・ ・
・−−・ −・ −−(8−4) 2 = 1. 'T
(1-α door (1-β]・θ) ・−・mountain・−(8
-53. Further, various errors are added to equation (7) as a disturbance term d([) to obtain equation (9).

dX(t) □=In・X(t)+B−U(t−L)+a (t−L)
−・・・・・・(9) dt However, U(t-L)=Uw(t-LJ+[JE(t-
LJ ・−・o(j).

Hereinafter, formulas (8-1) to <8-6) will be abbreviated as formula (8).

These equations (9) and 00 are used in the feedback control system of the present invention, depending on the actual measured values of the amount of raw material transported, the weight of the raw material in the water sprinkling tank, the amount of water added, and the amount of moisture in the raw material after water addition. This is used when calculating the total amount of added water after correcting the settings for IJ Kus A and B4.

Embodiment FIG. 1 is a diagram showing the configuration of the NO control system in an embodiment of the present invention. The control system of this embodiment consists of a feed-7 forward control system and a feed/back control system, and the feedback control system is an adaptive process model control system. In FIG. 1, the same reference numerals as in FIG. 3 are used to denote each device for the sintering process, and the devices are similar to the devices in FIG. 3. In Fig. 1, 1 is a target moisture setting device;
Moisture target value R4'f after water addition is set by virtually dividing the target values R, ff of the feed/7-word control system and the target value Rfb of the feed/notch control system using a certain division ratio m. That is, "a="ff+FLfb ------(11-I
IRH,=m−Rtt −−・−・−−−
-(11-2JFLB=(t-ml・a, -=
------(11-33 However, O<m<1 Here, the division ratio m may be a value determined in advance by experiment, but in this example, it is set to correspond to the raw material water content ai before water addition. A table is created in advance, and values corresponding to preliminary values of raw material moisture ai, which will be described later, are extracted.

The target value "ff" is the added water J of the feed/7-oward control system.
lt - Set for the computing unit 3 to calculate the target value FL
fb is set for the calculator 5 that calculates the amount of water added to the feed pack control system. 2 is the raw material moisture R before water addition
This is a calculation unit that predicts and calculates i, and it calculates the actual measured value of added water i'ow from the added water flow meter 9 and the raw material water movement after water addition from the raw material moisture detector 8. The actual measured value of ■ and the amount of raw material transported before water addition from the raw material weight before hydrogenation detector 10 (actual measured value of Ji)
A predicted value of the raw material water content FLi before water addition is calculated from equation (1) using Note that it goes without saying that the delay in measurement timing of each actual measurement value used in this calculation must be compensated for. In addition, the cycle of calculating the predicted value is determined according to the time required to transport the sintered raw material from the position of the raw material weight detector 10 before hydrogenation to the position of the raw material moisture detector 8, and the calculated value is calculated each time. Although it may be used as a predicted value as it is, it can be
It is preferable to use the predicted value after correcting periodic fluctuations and sudden abnormal values.

3 is a calculator for calculating the amount of water added in the feed forward control system; Using the water target value FLff of the forward control system and the actual measured value of the raw material transportation amount Ui before water addition from the raw material weight detector 10 before hydrogenation, the added water amount Uw of the feed forward control system is calculated from equation (1). -calculate ff. 4 is a calculation setting device that calculates and sets the formula for calculating the total amount of water added in the feed/7972% 1llII system (matrix A and BQ in (9) 2i above. Values of coefficients α, β, and θ corresponding to various values of raw material transportation amount U1, added water amount OWN, raw material weight within watering span W1, raw material water direction after water addition, and raw material transportation after water addition tUo are stored in table format. Actual value of each value■,■,■,■,■
Corresponding α, β, θ are extracted according to , 1°K2'z is calculated as a coefficient from this, and further matrices A, Be! and set it in the feed/noise control calculator 5.

Reference numeral 5 is a computing unit that calculates ml of added water in the feedback control system, which calculates the moisture target value "fb" of the feedback control system from the target moisture setting unit 1 and water addition from the pre-water addition water molecule measuring unit 2. The previous predicted value of the raw material moisture Ri, the values of matrices A and B from the feed forward control calculator 3, the actual measured value of the raw material transport amount i before adding water ■, and the actual measured value of the raw material moisture RO after adding water ■ Actual measurement of raw material weight W within the watering span ■
Added water amount Uwsf of the feed pack control system using
Calculate b. The calculation method is d(t-L) in equation (9)
and UB of Equation 01 (if the t-LJ term is considered as a disturbance term, use Equation (9) and Equation 01, and the solution method is "System and Control" magazine published by Japan Automatic Control Association, 1984, Val. 2
It is carried out according to the method described in 845F, 269-277.

If the UB(t-LJ term is not used as a disturbance term, calculate the formula 8-63 and follow the rules and 7 different solutions.

Note that the raw material water content after water addition used in the above calculation ((8
xll in equation -13 uses the difference between the actual measurement value of the raw material moisture detector 8 and the target value of the feed φ notch control system.

Reference numeral 6 denotes an added water flow rate control device, which controls the amount of added water Uw-ff of the fee forward control system input from the feed forward control calculator 3 and the feed back control system input from the feed back control calculator shi. Added water Et
Uw−rbe is added to obtain the amount of water added U, (=Uw, H+
UW*(d)k is determined, and the water sprinkler 7 is controlled based on this amount of added water. Note that 11 is a detector for the weight of the raw material within the water sprinkling span, and 12 is a detector for the weight of the raw material after water addition.

FIG. 2 shows the time course of the amount of added water and the actual measured value of raw water for 2 minutes at the water addition edge when water content is controlled using the apparatus shown in FIG. In the same figure, the curve ■ indicates the amount of added water (ton/hrJ), and the curve ■ indicates the actual measured raw material moisture value (sword). The standard deviation of the value must be 0.1% or less,
1/ compared to the fluctuation of the conventional method (standard deviation of about 0.3 inches)
It was 3 or less.

Effects of the Invention As described above, according to the present control method, the moisture content of the sintering raw material can be kept constant, and the productivity and quality of the sintered ore can be greatly improved.

[Brief explanation of the drawing]

FIG. 1 is a control system diagram explaining the present invention in detail, FIG. 2 is a graph showing a series of effects of the present invention, and No. 39 is a control system diagram showing a conventional method. DESCRIPTION OF SYMBOLS 1...Target moisture setting device, 2...Water molecule measuring calculator before water addition, 3...Feed forward control calculator, 4...
... Feedback control coefficient calculation setting device, 5 ... -Feed / rack control device, 6 ... Added water flow rate control device, 7 ... Water sprinkler device, 8 ... Raw material moisture detector, 9
... Added water flow meter, 10... Raw material weight detector before hydrogenation, 11... Raw material weight detector in water sprinkling span, 12...
- Water-added superior raw material weight detector, 31... Moisture meter, 33-
1゜33-2... Arithmetic controller, 34-1.34-2.
... Water sprinkler, 35... Delay circuit, W1 to W4...
Raw material hollow A-(11... Cutting conveyor, C2...
Charging conveyor, C3...Transfer conveyor, M...
Mixer, H...Hopper〇Representative Patent attorney Masaaki Akizawa Mitsunobu 1 person Figure 7i3

Claims (1)

[Claims] (1) In the raw material moisture control method in the sintering process, which controls the amount of water added to the sintering raw material so that the raw material moisture reaches a target value, there is a feed forward control system based on the raw material moisture before water addition. The overall control system is constructed by combining the feed-back control system based on the raw material moisture content after water addition, and the target value of the raw material moisture content after water addition is fed back to the target value of the feed-forward control system. The target value of the control system is virtually divided using a certain division ratio, and in the feed/forward control system, the amount of added water is calculated based on the actual measured values of the raw material moisture content after water addition and the raw material transport amount before water addition. The required amount of added water for the feed forward control system is calculated using the predicted value of the raw material moisture before water addition, which is calculated from time to time.In the feed back control system, the actual raw material moisture content after water addition is Using the value corrected according to the target value of the back control system,
In addition, the required amount of added water for the feed-back control system is calculated using a formula for calculating the amount of added water that includes a coefficient that is corrected according to fluctuations in the raw material moisture and the amount of material transported, and the required amount of added water for the feed-forward control system calculated from these is calculated. A method for controlling moisture in a sintering raw material, characterized in that the amount of water added to the sintering raw material is set to the total value of the amount of water and the amount of added water necessary for a feedback control system.