JPH0772670B2 - Method for reducing uneven burning of sinter - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for reducing uneven burn of sinter in a Dwightroid type sintering machine.

[Conventional technology]

In the Dwightroid type moving grid type sintering machine, observing the sintering state of the sinter ore packed bed on the pallet at the end of the sinter of the sinter machine, the sintering progressed sufficiently in the width direction of the packed bed on the pallet. In some cases, a so-called uneven burning phenomenon may be observed due to the presence of a burnt portion and a portion in which firing has not progressed sufficiently (non-fired portion).

When such uneven burning in the width direction occurs, the quality (falling strength, particle size, chemical composition, etc.) of the sintered ore is deteriorated or varied, and the occurrence rate of returned ore increases. As a result, there are many adverse effects on the production of sinter, such as a decrease in production.

Therefore, the wind box temperature Ti in the pallet width direction in the sinter machine mine or the red tropical cross-section HZRi of the sinter cake in the mine mine should be measured, and the raw material supply in the pallet width direction should be adjusted based on the results. Is being done.
For example, these are Japanese Examined Patent Publication No. 40-40361 and Japanese Examined Patent Publication No. 51-2.
It is disclosed in Japanese Patent No. 3365, Japanese Patent Publication No. 6010096, and the like.

FIG. 3 is a schematic diagram for explaining this, and is an explanatory diagram in which a measurement and control system is added to a perspective view of a main part of the sintering machine.

In FIG. 3, 1 is a feed hopper, 2 is a raw material supply drum feeder, 3 is a main gate whose opening is set according to the production amount, and 4 is a pallet.

A division operation type adjustment gate 5 is provided for finely adjusting the widthwise supply amount of the drum feeder 2. The adjustment gate 5 is driven by a power cylinder 6. The layer thickness Hi of the raw material layer A on the pallet is measured by the ultrasonic level meter 7. IT that measures the measured value of the windbox thermometer 8 in the mine ore and the red tropical cross section of the sinter cake in the mine ore
The observation data of the V camera 9 is the upper process computer 10
, And the output of the upper process computer 10 is input to the lower microcomputer 11 to perform necessary control.

In the prior art, the exhaust box windbox temperature Ti or the red tropical cross-sectional area HZRi of the sinter cake in the exhaust section is continuously measured, and the process computer 10 eliminates variations in Ti and HZRi so that the layer thickness deviation in the width direction Δ Hisv, that is, the difference between the average layer thickness and the measured layer thickness is set at regular intervals. In the microcomputer 11, the power cylinder 6 is driven to control the opening degree of the adjustment gate 5 so as to match the instruction value ΔHisv from the process computer based on the measurement result of the layer thickness Hi. The average layer thickness is controlled so that the supply amount (discharging amount) is controlled by controlling the number of rotations of the drum feeder 2 and the set layer thickness is obtained.

Generally, the layer thickness ΔHisv is set in each width direction mainly to smooth the temperature Ti of the mine ore, but the method of giving this set value was the most difficult point in this control.

[Problems to be Solved by the Invention]

The relationship between the bed thickness Hi in each width direction and the windbox temperature Ti of the mine ore was investigated over 4 days and is shown in Fig. 4. Fourth
As shown in the figure, since the layer thickness Hi and the temperature Ti have a negative correlation,
The layer thickness Hi should be increased in the rows with good ventilation and high temperature Ti, and the layer thickness Hi should be decreased in the opposite row. However, this layer thickness Hi and temperature Ti
The relationship of changes with place and with time. In Fig. 4, enter the measured values for each of No. 1 to 5 gates,
The relationship is shown by five straight lines. Thus, the layer thickness
The relationship between Hi and temperature Ti changes depending on the place and time. for that reason,
A system is conceivable in which the correlation between the layer thickness Hi and the temperature Ti is obtained for each column based on the data of the last few hours, and the action width of the layer thickness Hi is determined based on the slope of the straight line.

However, as factors affecting the exhaust box wind box temperature Ti, in addition to the layer thickness Hi, there are various factors such as the packing density of the sintering raw material on the pallet, the grain size composition, the water content or the clogging of the pallet, and the leakage of air. Since a factor is involved, a clear relational expression is rarely obtained even if the correlation between the layer thickness Hi and the temperature Ti is investigated with data of several hours.

Therefore, under the present circumstances, it is assumed that the variation width of the temperature Ti with respect to the variation amount of the layer thickness Hi is constant, and the layer thickness deviation ΔHi is set and controlled in each width direction. In order to perform finer control to eliminate the variation in the temperature Ti in the width direction, it is necessary to review the relationship between the layer thickness Hi and the temperature Ti every several hours for each column.

[Means for Solving the Problems]

However, even when the relationship between the absolute value Hi of the bed thickness and the absolute value Ti of the windbox temperature of the mine ore was obtained for each row, a good correlation could not be obtained due to the influence of other factors.

Therefore, in order to eliminate the influence of factors other than Hi that affect Ti as much as possible, the relationship between the widthwise layer thickness deviation ΔHi and the widthwise windbox temperature deviation ΔTi was sought. An example is shown in Fig. 2, but there was a very good correlation between ΔHi and ΔTi. The data is for the last 4 hours and the data here is a 30 minute average. In addition, the layer thickness Hi and the windbox temperature Ti of the mine ore are correlated with a time delay of about 30 minutes considering the traveling time.

In this way, there is always a good correlation between the widthwise layer thickness deviation ΔHi and the widthwise ore discharge part windbox temperature deviation ΔTi.
The present inventors have completed the present invention by finding that a system for determining the layer thickness action amount using the slope Ki of this regression equation enables more fine-grained uneven burn management in the width direction.

In the operation of the Dwightroid-type sintering machine, the present invention calculates the deviation ΔTi between the average temperature of a plurality of pallets in the i-th row and the average temperature in the pallet width direction for a plurality of rows in the pallet width direction in the mine side windbox. On the other hand, the deviation ΔHi between the average layer thickness of the plurality of pallets in the i-th row and the average layer thickness in the pallet width direction of the packing thickness of the plurality of columns in the pallet width direction on the mine side is calculated, and the corresponding width is calculated. Direction of each ΔHi corresponding to the change amount of each ΔHi is performed regression analysis to estimate the correction amount of the layer thickness of the i-th column, and the layer thickness of each column in the pallet width direction is estimated based on the estimated correction amount. Is a method for reducing uneven burn of sintered ore, which is characterized by adjusting unevenness.

[Action]

The system configuration itself used for implementing the present invention is the same as the conventional technique shown in FIG. The present invention is a method for setting the layer thickness deviation ΔHisv in a process computer, and its schematic flow is shown in FIG.

FIG. 1 shows a control system for making the exhaust box wind box temperature Ti uniform at five locations in the pallet width direction.

Layer thickness Hi for each row for each pallet to ensure data correspondence
j, Windbox temperature Tij of the mine is sampled. When the data of the specified number of pallets n is accumulated, average values ▲ ▼ and ▲ ▼ are obtained for each pallet width direction (each column). Furthermore, the average value of all columns And the deviations ΔHi and ΔTi from the average value of all columns are calculated for each column. The ΔHi and ΔTi data are saved in the file.

When the learning cycle is reached, a regression analysis of ΔTi and ΔHi is performed using the data for the last 4 hours or so for each pallet width direction (each column). The correlation coefficient γi of the obtained regression line is the reference value γo
In the above case, Ki is updated from the previous Ki with the slope of the regression line.

Ki is defined for each column (i = 1 to 5).

This Ki and the latest row box exhaust box temperature deviation of each line △
The next layer thickness setting value Hisv is calculated for each column using Ti and the average layer thickness value for each column. Learning cycle (about every 2 hours)
If not reached, Ki before update and latest △ Ti, ▲
Hisv is calculated from ▼.

Is controlled by the number of rotations of the drum feeder 2, but in this system, the deviation from is to be controlled, so the layer thickness deviation set value ΔHisv is calculated in the pallet width direction. △ Hisv for each row
Regarding the above, the operation constraint condition is checked, and the subordinate microcomputer is instructed. In the microcomputer, PID control is performed on the sub-gate opening of each row so that ΔHisv is achieved.

The above control flow is repeated every time n pallets are passed. n
Can be set arbitrarily.

〔Example〕

Captain 58m, pallet width 3.5m, 15 windbox DLs
Using a sintering machine, mass production 8500t / day, layer thickness 630-660m
The present invention was carried out under the operating conditions of m and pallet speed of 1.8 to 2.2 m / min.

The following three types of operations were performed under the same raw material conditions.

(1) No adjustment gate control The opening of the adjustment gate 5 is constant, and ventilation is adjusted only by changing the pallet speed and average layer thickness.

(2) With adjustment gate control (conventional method) The opening of the adjustment gate 5 in order to smooth the gas temperature in the pallet width direction in the No. 14 wind box (14th wind box among 15 wind boxes). To control. The layer thickness deviation ΔHisv is set assuming that the change of Ti with respect to the change amount of the layer thickness Hi in the width direction is constant.

(3) With adjustment gate control (invention method) No.14 Temperature in pallet width direction in wind box (T
In order to smooth i), the adjustment gate is controlled by the flow of FIG.

The above operations (1) to (3) were each performed for one week, and the results shown in Table 1 were obtained.

By adjusting gate control, uneven burning in the width direction of the pallet was reduced, variation in the wind box temperature in the width direction was reduced, and as a result, the average layer thickness and shutter strength were improved, and the occurrence rate of returned ore was reduced. Even with the control method by the conventional method, the occurrence rate of the returned ore of 0.9% is lower than that without the control, but the occurrence rate of the returned ore of 0.7% is further reduced by the method of the present invention. It is now possible to manage fine burn spots. In addition, the product shutter strength is also reduced compared to the conventional method due to the reduction of brittle sinter cake.
Improved by 0.3%.

[Advantages of the Invention] In the Dwightroid-type sintering machine, the method for reducing unevenness in burning according to the present invention takes into account the quality control in the pallet width direction and the influence of changes in raw material conditions over time, which were difficult with the conventional method, and a fine pallet. It becomes possible to control the firing in the width direction, which has a great effect on improving the yield of sintered mass and the strength of sinter.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flowchart for uneven burn control according to the method of the present invention,
Fig. 2 shows the relationship between the widthwise layer thickness deviation ΔHi and the widthwise windbox temperature deviation ΔTi, Fig. 3 is a block diagram showing the burn unevenness control system configuration, and Fig. 4 is the layer thickness Hi and windbox temperature Ti. It is a graph which shows a relationship. 1 …… Mine feeding hopper 2 …… Drum feeder 3 …… Main gate 4 …… Pallet 5 …… Adjustment gate 6 …… Power cylinder 7 …… Ultrasonic wave level meter 8 …… Sinking section windbox thermometer 9 …… ITV camera 10 …… Process computer 11 …… Microcomputer

Claims (1)

[Claims] 1. A deviation ΔTi between the average temperature of a plurality of pallets in the i-th row and the average temperature in the pallet width direction of a plurality of rows in the pallet width direction in the windbox on the mine ore side during the operation of the Dwightroid type sintering machine. On the other hand, the deviation ΔHi between the average layer thickness of the plurality of pallets in the i-th column and the average layer thickness in the pallet width direction of the plurality of columns in the pallet width direction on the mining side is calculated, and corresponding Regression analysis of each ΔTi corresponding to each ΔHi change amount in multiple columns in the width direction is performed to estimate the correction amount of the layer thickness in the i-th column, and the layers in each column in the pallet width direction are estimated based on the estimated correction amount. A method for reducing uneven burning of a sinter, which comprises adjusting thickness to prevent uneven burning.