JP2012219343A - Weighed value correction method, pulverized coal injection amount estimating method and pulverized coal injection amount estimating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable to estimate mass of an injection tank at a prescribed accuracy by correcting a measured value of a weighed value of the injection tank in such a manner as to be simple and be able to absorb characteristic change with elapsed time.SOLUTION: An upper tank 7 storing pulverized coal and the injection tank 8 are connected in series, and the pulverized coal can be injected from the injection tank 8 into a blast furnace 9. Further, a PC hopper 6 connected to the upper tank 7 in series is provided. By using a correction factor β found based on a value provided by integrating variation per unit time of the weighed value of the PC hopper 6, and a value provided by integrating variation per unit time of the weighed value of the injection tank 8, the weighed value of the injection tank 8 is corrected to find the mass of the injection tank 8.

Description

  The present invention relates to a technique for controlling the amount of pulverized coal injection in pulverized coal injection equipment for continuously supplying pulverized coal to a blast furnace.

In order to control the amount of pulverized coal injection, the pulverized coal injection speed is calculated from the change over time of the mass of the injection tank (lower tank) that injects pulverized coal into the blast furnace. For this reason, grasping the mass of the injection tank is very important.
However, since the injection tank is mechanically connected to the upper tank as described in Patent Document 1, a mass measurement value (weighing value) in which the mass of the injection tank and the mass of the upper tank are weighed together. Affects each. Further, the gas pressure (high pressure) in each tank also affects the mutual mass measurement value.
In order to reduce this influence, a corrected mass is obtained from each mass value and pressure value, and the measured value of the injection tank is corrected by the obtained corrected mass (see Patent Document 1).

Japanese Patent No. 274001

FIG. 3 is a diagram illustrating a state in which the pressure Fp and the mass Fw of the upper tank affect the mass of the injection tank.
In order to correct the measurement error due to this influence, conventionally, for example, calculation is performed as correction function mass ΔWinj = correction function f (Fp, Fw). In addition, since the pressure and mass of the injection tank influence the measurement of the mass of the upper tank, it is necessary to calculate the influence from the injection tank to the upper tank in the same manner.

The correction function f is calculated from an experiment or a model, and necessary parameters are adjusted. However, it takes time and effort to adjust the parameters.
Further, in order to make the corrected mass obtained as described above correspond to the change in characteristics over time, maintenance such as periodic readjustment work is required.
The present invention pays attention to the above points, and estimates the mass of the injection tank with a predetermined accuracy by correcting the measured value of the measurement value of the injection tank so that the characteristic change with time can be easily absorbed. The purpose is to make it possible.

In order to solve the above problems, the invention described in claim 1 of the present invention is such that an upper tank and a lower tank for storing pulverized coal are connected in series, and pulverized coal can be blown into the blast furnace from the lower tank. In a weighing value correction method for correcting a weighing value of the lower tank in a pulverized coal blowing facility provided with a supply unit that is connected in series to the upper tank and supplies pulverized coal to the upper tank. The weighing value of the lower tank is calculated by a correction coefficient obtained based on a value obtained by integrating the amount of change per unit time of the weighing value of the supply unit and a value obtained by integrating the amount of change of the weighing value of the lower tank per unit time. By correcting the above, the mass of the lower tank is obtained.

Next, the invention described in claim 2 is the configuration described in claim 1, wherein the correction coefficient is a value obtained by integrating the amount of change per unit time of the weighing value of the lower tank. It is characterized by being expressed as a ratio of values obtained by integrating the amount of change per unit time of the weighing value.
Next, the invention described in claim 3 is based on the weighing value correction method of claim 1 or claim 2 and based on the weighing value of the lower tank after being corrected with the correction coefficient, the amount of pulverized coal injection into the blast furnace. The present invention provides a pulverized coal injection amount estimation method characterized by estimating

Next, in the invention described in claim 4, an upper tank and a lower tank for storing pulverized coal are connected in series so that pulverized coal can be blown into the blast furnace from the lower tank, and the upper tank is A pulverized coal injection amount estimation device for estimating an amount of pulverized coal injection from the lower tank to the blast furnace in a pulverized coal injection facility provided with a supply unit for supplying pulverized coal to the upper tank connected in series,
A weighing device for a feeding unit for weighing the feeding unit, a weighing device for a lower tank for weighing a lower tank,
A first integrated value calculating unit for calculating a first integrated value obtained by integrating the amount of change per unit time of the measured value weighed by the supply unit weighing device;
A second integrated value calculation unit for calculating a second integrated value obtained by integrating the amount of change per unit time of the measured value weighed by the lower tank weighing device;
From the first integrated value S1 and the second integrated value S2 calculated by the first integrated value calculating unit and the second integrated value calculating unit, respectively, and the weighing value W1 weighed by the lower tank weighing device, the following (2) A weighing value correction unit for obtaining a mass W1 ^* which is a weighing value of the lower tank after correction by an equation;
An injection amount calculation unit that estimates an injection amount of pulverized coal into the blast furnace based on the mass W1 ^* obtained by the weighing value correction unit.
W1 ^* = (S1 / S2) · W1 (2)

  According to the present invention, the error of the weighing value can be corrected (corrected) with the correction coefficient including the fluctuation of characteristics over time. Therefore, it becomes possible to achieve accuracy improvements such as the speed of blowing pulverized coal into the blast furnace and the management of the amount of blown coal. This leads to stabilization of blast furnace operation and improvement of basic unit management accuracy.

It is a block diagram of the pulverized coal injection equipment which concerns on embodiment based on this invention. It is a figure explaining the structure of a pulverized coal injection flow rate control part. It is a figure explaining the influence between tanks.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram of a pulverized coal injection facility.
(Constitution)
Coal stacked in the raw material yard 1 is gas-transported to the coal hopper 3 through the intermediate hopper 2 and further pulverized into a pulverized coal by the coal mill 4 to become a pulverized coal. The pulverized coal is sent to the bag filter 5 by gas transportation, and is collected by the bag filter 5. The collected pulverized coal is stored in the PC hopper 6 which is a supply unit.

  Further, the PC hopper 6, the upper tank 7, and the injection tank 8 (lower tank) are connected in series in the vertical direction so that pulverized coal can be charged from the PC hopper 6 to the upper tank 7, that is, supplied. At the same time, pulverized coal can be discharged or supplied from the upper tank 7 to the injection tank 8. Furthermore, pulverized coal can be continuously blown into the blast furnace 9 from the injection tank 8 through the tuyere 9a by gas transportation. The air compressor of the code | symbol 10 is an apparatus which blows in the air (booster gas) for gas transport. The air flow rate and pressure by the air compressor 10 are adjusted by controlling each valve based on a command from a pulverized coal injection flow rate control unit 20 described later.

The N2 compressor 11 is an apparatus for adjusting the pressure in the tanks 7 and 8 by supplying inert gas to the injection tank 8 and the upper tank 7 to individually pressurize the tanks 7 and 8. It is. The high-pressure inert gas from the N2 compressor is adjusted by controlling each valve based on a command from a pulverized coal injection flow rate control unit 20 described later.
Here, the inside of the PC hopper 6 is at atmospheric pressure, and the inside of the blast furnace 9 is at high pressure. For this reason, it is necessary to always keep the inside of the injection tank 8 at a high pressure. For this reason, the inside of the injection tank 8 is kept in a state of being constantly pressurized by the N2 compressor 11.

  On the other hand, the upper tank 7 is in an atmospheric pressure state (pressure smaller than the pressure of the injection tank 8) when pulverized coal is introduced from the PC hopper 6, but when the pulverized coal is discharged to the injection tank 8, the injection tank. 8 to the same pressure. That is, when the upper tank 7 is at atmospheric pressure, pulverized coal is transported from the PC hopper 6 to the upper tank 7. Next, the upper tank 7 is sealed, and the pressure is injected to the same pressure as the injection tank 8 to equalize the pressure. By repeating this, pulverized coal can be transported from the PC hopper 6 at atmospheric pressure to the injection tank 8, and the pulverized coal can be continuously blown into the blast furnace 9.

Further, a hopper weighing machine 12 for measuring the mass of the PC hopper 6, an upper tank weighing machine 13 for measuring the mass of the upper tank 7, and a lower tank weighing machine 14 for weighing the mass of the injection tank 8 are provided. An example of a weighing machine is a load cell.
Each weighing machine 12, 13, 14 outputs the measured weighing value (mass) to the pulverized coal injection flow rate control unit 20.

  Here, in a state where the injection tank 8 is cut off from the upper tank 7, the time change of the mass measurement value of the injection tank 8 corresponds to the blowing speed of the pulverized coal into the blast furnace 9. For this purpose, the mass of the injection tank 8 is weighed. The reason why the mass of the upper tank 7 is weighed is to control the amount of charging from the upper tank 7 to the injection tank 8 by grasping the mass of the upper tank 7. Thus, it is very important to grasp the masses of the upper tank 7 and the injection tank 8. However, since the upper tank 7 and the injection tank 8 are mechanically connected to each other, they are affected by each mass. Further, since the tank pressure is high, it is also influenced by the tank pressure.

And this embodiment has one of the characteristics in the point which utilized the integrated value of the mass change of the PC hopper 6 which was not used until now for correction | amendment of the said weighing value.
The pulverized coal injection flow rate control unit 20 is an arithmetic unit, and as shown in FIG. 2, the hopper integrated value calculating unit 20A, the upper tank integrated value calculating unit 20B, the lower tank integrated value calculating unit 20C, Tank correction coefficient calculation unit 20D, lower tank correction coefficient calculation unit 20E, upper tank mass correction unit 20F, lower tank mass correction unit 20G, pulverized coal injection amount estimation unit 20I, upper tank discharge amount estimation unit 20H, pulverized coal injection A quantity adjusting unit 20J is provided.

  The integrated value calculation unit for hopper 20A constitutes a first integrated value calculation unit, calculates the amount of change per unit time by differentiating the weighing value W3 measured by the hopper weighing machine 12, and the calculated amount of change Are sequentially integrated to calculate the hopper integrated value S1. In the time differentiation, for example, a difference from the previously acquired weighing value is obtained as a differential value (change amount) for each weighing value acquisition cycle set in advance. And the differential value (change amount) calculated | required for the weighing value acquisition cycle unit is integrated | accumulated. The same applies to the processing of the integrated value calculation unit below.

The integrated value calculation unit 20B for the upper tank calculates the amount of change per unit time by differentiating the measured value W2 measured by the upper tank weighing machine 13 with time, and sequentially integrates the calculated amount of change to integrate the upper tank. The value S3 is calculated.
The lower tank integrated value calculation unit 20C constitutes a second integrated value calculation unit, which calculates the amount of change per unit time by differentiating the weighing value W1 measured by the lower tank weighing machine 14 with respect to time. The lower tank integrated value S2 is calculated by sequentially integrating the amount of change.

The upper tank correction coefficient calculation unit 20D calculates the ratio of the hopper integrated value S1 to the upper tank integrated value S3 by using the hopper integrated value S1 and the upper tank integrated value S3 as shown in the following equation (3). Obtained as tank correction coefficient α.
α = k1 · (S1 / S3) (3)
Note that the gain k1 is normally set to “1”, but other than “1” may be set as appropriate based on equipment conditions and prior experiments.

The lower tank correction coefficient calculation unit 20E uses the hopper integrated value S1 and the lower tank integrated value S2 to reduce the ratio of the hopper integrated value S1 to the lower tank integrated value S2 as shown in the following equation (4). Obtained as tank correction coefficient β.
β = k2 · (S1 / S2) (4)
The gain k2 is normally set to “1”, but may be set to a value other than “1” as appropriate based on equipment conditions and prior experiments.

The upper tank mass correction unit 20F corrects the weighing value W2 by multiplying the weighing value W2 weighed by the upper tank weighing machine 13 by the correction coefficient α for the upper tank as shown in the following equation (5). Then, the mass W2 ^* of the upper tank 7 which is the weighed value after correction is obtained.
W2 ^* = α · W2 (5)
The lower tank mass correction unit 20G corrects the weighing value W1 by multiplying the weighing value W1 weighed by the lower tank weighing machine 14 by the lower tank correction coefficient β as shown in the following equation (6). The mass W1 ^* of the lower tank, which is the weight value after correction, is obtained.
W1 ^* = α · W1 (6)

Here, the lower tank correction coefficient calculation unit 20E and the lower tank mass correction unit 20G constitute a weighing value correction unit.
The pulverized coal injection amount estimation unit 20I estimates the pulverized coal injection amount from the lower tank mass W1 ^* obtained by the lower tank mass correction unit 20G. For example, the pulverized coal injection speed is obtained from the differential value (change amount per unit time) of the mass W1 ^* , and the pulverized coal input amount from the injection tank 8 to the blast furnace 9 is obtained from the obtained integrated value of the injection speed.

The upper tank payout amount estimation unit 20H, for example, as shown in the following equation (7), W1 ^* is the measured value of the lower tank obtained by the lower tank mass correction unit 20G after the pulverized coal discharge to the injection tank 8, and the injection tank The upper tank discharge amount is obtained from the difference between the measured value of the lower tank obtained by the lower tank mass correction unit 20G after the pulverized coal discharge to 8 and W1 ^* .
Upper tank discharge amount = (W1 ^* after discharge)-(W1 ^* before discharge)
... (7)

Of course, the upper tank discharge amount may be obtained based on the mass W2 ^* obtained by the upper tank mass correction unit 20F.
The pulverized coal injection amount adjustment unit 20J is supplied with the pulverized coal injection amount or the injection speed to the blast furnace 9 obtained by the pulverized coal injection amount estimation unit 20I, and the input amount (discharge) from the upper tank 7 obtained by the upper tank discharge amount estimation unit 20H. On the basis of the amount), each valve is adjusted so that the pulverized coal injection amount into the blast furnace 9 becomes a preset target injection amount, and the flow rate of gas transportation and the like are controlled.

(Correction principle)
Here, the validity of the correction method will be described.
The PC hopper 6, the upper tank 7, and the injection tank 8 are connected in series, and the PC hopper 6 is at the top, and pulverized coal is charged (dispensed) in stages from upstream to downstream.
For this reason, the mass (weighing value) in each part 6, 7, and 8 can be approximated by the following formula.
PC hopper mass W3 ^* = weighing value W3
Upper tank mass W2 ^* = weighing value W2 + correction function mass 1
Injection tank mass W1 ^* = Weighing value W1 + Correction function mass 2

Here, the correction function mass 1 and the correction function mass 2 are functions using the mass and pressure of the upper tank 7 and the mass and pressure of the injection tank 8 as parameters, respectively.
For example, assuming that the mass of the upper tank is x (: variable), the influence of the mass x on the injection tank mass, that is, the correction amount can be approximated by the following quadratic function.
Correction function mass 2 = a · x ² + b · x + c

Here, a, b, and c are parameters of the function, and are values obtained experimentally or physically.
However, the above parameters are numerical values unique to the system, and are values that need to be adjusted when the system characteristics change over time. When the parameters a, b, and c are experimentally determined, the upper tank mass and pressure, the injection tank mass and pressure are changed, and the effect of the change on the injection tank 8 is measured and approximated by the quadratic function. It becomes. For this reason, it takes time and labor.

On the other hand, in this embodiment, it correct | amends based on the following thoughts.
The relationship between the input value and the integrated value of the payout amount in each part 6, 7, and 8 can be expressed by the following equation (8). The validity of this equation increases as the cumulative value of the integrated amount increases.
Σ (PC hopper input amount) = Σ (upper tank discharge amount)
= Σ (injection tank discharge amount)
... (8)

  Then, paying attention to the relationship of the above equation (8), it was decided to correct other hopper masses based on “Σ (PC hopper input amount)”. Here, since the PC hopper 6 is charged in an atmospheric pressure state at a constant pressure that is significantly smaller than the pressure in the injection tank 8, it is determined that the mass correction term is unnecessary. In the present embodiment, correction is performed based on the integrated amount “Σ (PC hopper input amount)” of the PC hopper 6 at the most upstream position.

If there is no mutual influence by the mass and pressure (high pressure) of the tanks 7 and 8 as described above, the following equation (9) should be satisfied from the relationship of the above equation (8).
Σ (PC hopper input amount) / Σ (upper tank discharge amount) = 1
Σ (PC hopper input amount) / Σ (injection tank discharge amount) = 1
... (9)

However, the above equation (9) does not hold due to the mutual influence between the tanks 7 and 8 as described above. In the present embodiment, the mutual influence between the tanks 7 and 8 is corrected using this.
That is, the correction coefficient α for the upper tank and the correction coefficient β for the lower tank, which are correction coefficients due to the mutual influence between the tanks 7 and 8, with the integrated value of the change in the weighing value of the PC hopper 6 as a reference (10) Can be set based on the formula.
α = Σ (PC hopper input amount) / Σ (upper tank discharge amount)
β = Σ (PC hopper input amount) / Σ (injection tank discharge amount)
... (10)

Since the upper tank correction coefficient α and the lower tank correction coefficient β are obtained as gains, they can be corrected as shown in the following equations (11) and (12).
Upper tank mass W2 ^* = α × (weighing value W2) (11)
Injection tank mass W1 ^* = β × (weighing value W1) (12)

If at least the injection tank mass W1 ^* can be obtained with a predetermined accuracy by correcting as described above, the amount of discharge from the tanks 7 and 8 according to the following equations (13) and (14): Can be calculated.
Upper tank discharge amount = (mass after injection tank discharge (with correction))
-(Mass before and after discharge of injection tank (with correction))
... (13)
Injection tank delivery amount = ∫ (blowing speed) dt (14)

(Function and effect)
In the present embodiment, an independent weighing machine 12 is installed in the PC hopper 6 which is the front stage of the upper tank 7, and the integrated value of the change of the weighing machine 12 and the weighing values of the upper tank 7 and the injection tank 8 are calculated. The upper tank mass W2 and the injection tank mass W1 are corrected by comparing with the integrated value of the change.

For this reason, even if there is a change in characteristics over time, it is possible to obtain correction coefficients α and β including the change in characteristics over time. In other words, in this embodiment, weighing is performed based on changes in characteristics over time. The error of the value can be corrected. As a result, it becomes possible to achieve an improvement in the accuracy of pulverized coal injection speed and injection amount management into the blast furnace 9, thereby achieving stabilization of the blast furnace operation and improvement of the basic unit management accuracy.
In particular, as the accumulated value increases, the reliability of the correction coefficients α and β of the present embodiment improves.

  When correction is performed with the correction function mass as described above, it is necessary to adjust parameters when the system characteristics change over time. However, these parameters a, b, and c are experimentally determined. When obtaining, the upper tank mass and pressure, the injection tank mass and pressure are changed, and the influence of the mass on the injection tank 8 is measured and approximated by the quadratic function. For this reason, it takes time and labor. In the present embodiment, such labor and labor are not required.

  Here, when the injection tank payout amount obtained by the present embodiment and the injection tank payout amount obtained by the conventional method (value after adjusting the parameter of the correction function mass) were obtained, the method based on the present invention was used. It was confirmed that the injection tank payout amount can be obtained with higher accuracy by correcting.

6 PC hopper 7 Upper tank 8 Injection tank (lower tank)
9 Blast Furnace 12 Weigher for Hopper (Weighing Device for Supply Unit)
13 Upper Tank Weighing Machine 14 Lower Tank Weighing Machine (Lower Tank Weighing Device)
20 Pulverized coal injection flow rate control unit 20A Hopper integrated value calculation unit (first integrated value calculation unit)
20B Integrated value calculation unit for upper tank 20C Integrated value calculation unit for lower tank (second integrated value calculation unit)
20D Upper tank correction coefficient calculation unit 20E Lower tank correction coefficient calculation unit (weighing correction unit)
20F Upper tank mass correction unit 20G Lower tank mass correction unit (weighing correction unit)
20H Upper tank discharge amount estimation unit 20I Pulverized coal injection amount estimation unit (injection amount calculation unit)
20J Pulverized coal injection amount adjustment unit S1 hopper integrated value (first integrated value)
S2 Lower tank integrated value (second integrated value)
S3 Upper tank integrated value W1 Injection tank weight value W1 ^* Injection tank weight W2 Upper tank weight value W2 ^* Upper tank weight W3 PC hopper weight value W3 ^* PC hopper weight α Upper tank correction coefficient β Lower tank correction coefficient

Claims (4)

An upper tank and a lower tank for storing pulverized coal are connected in series so that pulverized coal can be blown into the blast furnace from the lower tank, and pulverized coal is connected to the upper tank in series. In a weighing value correction method for correcting a weighing value of the lower tank in a pulverized coal injection facility provided with a supplying unit, a value obtained by integrating the amount of change per unit time of the weighing value of the feeding unit, and the lower tank Weighing value correction characterized in that the mass of the lower tank is obtained by correcting the weighing value of the lower tank by a correction coefficient obtained based on a value obtained by integrating the amount of change per unit time of the weighing value of Method.   The correction coefficient is represented by a ratio of a value obtained by integrating the amount of change per unit time of the weighing value of the supply unit to a value obtained by integrating the amount of change per unit time of the weighing value of the lower tank. The weighing value correction method according to claim 1.   The amount of pulverized coal injection to the blast furnace is estimated based on the weight value of the lower tank after being corrected with the correction coefficient, based on the method for correcting the weight value according to claim 1 or claim 2. Estimation method. An upper tank and a lower tank for storing pulverized coal are connected in series so that pulverized coal can be blown into the blast furnace from the lower tank, and pulverized coal is connected to the upper tank in series. A pulverized coal injection amount estimation device for estimating an amount of pulverized coal injection from the lower tank to the blast furnace in a pulverized coal injection facility provided with a supply unit,
A weighing device for a feeding unit for weighing the feeding unit, a weighing device for a lower tank for weighing a lower tank,
A first integrated value calculating unit for calculating a first integrated value obtained by integrating the amount of change per unit time of the measured value weighed by the supply unit weighing device;
A second integrated value calculation unit for calculating a second integrated value obtained by integrating the amount of change per unit time of the measured value weighed by the lower tank weighing device;
From the first integrated value S1 and the second integrated value S2 calculated by the first integrated value calculating unit and the second integrated value calculating unit, respectively, and the weighing value W1 weighed by the lower tank weighing device, the following (1) A weighing value correction unit for obtaining a mass W1 ^* which is a weighing value of the lower tank after correction by an equation;
A pulverized coal injection amount estimation device comprising: an injection amount calculation unit that estimates an injection amount of pulverized coal into a blast furnace based on a mass W1 ^* obtained by a weighing value correction unit.
W1 ^* = (S1 / S2) · W1 (1)

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