JP2007177297A - Method and apparatus for controlling injection of fine powdery coal into blast furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To keep stable injection while restraining the inclined injection phenomenon without producing the above problem, when the injections from a plurality of injection tanks are parallel performed. <P>SOLUTION: In a method for injecting fine powdery coal into a blast furnace, with which three or more of injection tanks for storing the fine powdery coal for injecting into the blast furnace and a distributor are connected with one of communicatively connected supplying pipe-line on the way, and while pressurizing by supplying a gas into two or more of injection tanks, the fine powdery coal in each injection tank is supplied into the distributor through the supplying pipe-line together with the gas and the fine powdery coal supplied from the distributor is injected into the blast furnace; this control method is to control the gas volume for pressurizing, which is supplied into each injection tank so that the fine powdery coal supplied into the distributor becomes preset value, and further, it is desirable that the supplied volume of the gas for pressurizing is the same volume to the respective injection tanks. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a control method for stably injecting pulverized coal into a blast furnace and a control apparatus therefor.

  Coke charged to the blast furnace is used for reducing iron ore and plays an important role as a heat source in the furnace. However, because coke is expensive, instead of using this coke, pulverized coal with good flammability is blown from the blast furnace tuyere to reduce the amount of coke used and reduce hot metal production costs. Yes.

  It is important that the pulverized coal is blown into the blast furnace in a stable and continuous manner. For this purpose, various methods have been proposed. For example, as described in Patent Document 1, there is a method in which pulverized coal is blown into a blast furnace in parallel from a plurality of blowing tanks.

A general control method for such pulverized coal injection will be described with reference to FIG.
The pulverized coal in each of the injection tanks 2-1 to 2-4 passes through each supply pipe 4, the disperser 1, the distributor 6, and the tuyere 8 provided with the injection valves 9-1 to 9-4 in order. Is being blown into the blast furnace 7. And the gas flow regulating valve 3a for pressurization provided in the gas supply piping 3 and the exhaust pressure piping 5 so that it may become the pressure in each blowing tank 2-1 to 2-4 according to the target blowing amount to the blast furnace 7. The opening degree of both of the exhaust pressure valves 5 a provided in the control is adjusted by the blow control calculation unit 22.
In this blowing control calculation part 22, the pulverized coal from the blowing tank 2-1 calculated | required from the time change of the weight W of the whole blowing tank 2-1 measured with the load cell 10 provided in the blowing tank 2-1. Of the pressurizing gas flow control valve 3a and the exhaust gas so that the internal pressure of the blowing tank 2-1 measured by the pressure gauge 11 provided in the blowing tank 2-1 becomes a preset value. An adjustment instruction is given regarding the opening of the pressure valve 5a.

JP 2004-43849 A

  However, when pulverized coal is blown in parallel from two or more plurality of blowing tanks as in Patent Document 1, no blowing is performed from one tank, and the entire amount is blown from the other tank. There is a case where a phenomenon called single blowing occurs. As a phenomenon peculiar to the solid-gas two-layer flow, the density of the pulverized coal is generated in the pipe 4 from the blowing tanks 2-1 to 2-4 to the disperser 1 which is a merging portion. Because the pressure loss of the piping changes depending on the density of the pulverized coal, a pressure difference is created at the confluence. At this time, since the amount of pulverized coal flows more on the high pressure side, and the amount of pulverized coal decreases on the low pressure side, the difference in density in the same pipe and the difference in density between the two pipes at the same time point. It is considered that the larger the pressure difference, the larger the pressure difference, and the above phenomenon appears due to the generated large pressure difference. In order to suppress this single blowing, it is necessary to quickly eliminate the pressure difference generated at the junction. However, the conventional blow control method with respect to the speed at which one blow occurs is a large amount of wasted time such as measuring the blow amount and operating time of each valve, so increasing the gain of the control system eliminates the pressure difference at the junction. Even if it is possible to do so, the control becomes unstable, so there is a limit, and it is difficult to suppress the occurrence of single blowing.

If this single blowing occurs, the switching cycle of the blowing tank may be disturbed, and continuous blowing may not be maintained.
In addition, since the control is performed individually for each blowing tank, there is a problem that a difference in the amount of blowing between the blowing tanks is likely to occur, and a deviation in the switching cycle of the blowing tanks is likely to occur.
It is an object of the present invention to suppress a single blowing phenomenon and maintain a stable blowing without having the above-mentioned problem when blowing in parallel from a plurality of blowing tanks.

The present invention has been made to solve the above problems, and means (1) includes three or more injection tanks for storing pulverized coal for blast furnace injection, each of the injection tanks, and a distributor. Is connected to one supply pipe connected in the middle, and gas is supplied to two or more injection tanks while pressurizing the pulverized coal in each of the injection tanks together with the gas through the supply pipe. In the method of blowing pulverized coal to the blast furnace where the supplied pulverized coal is blown into the blast furnace from the distributor, the amount of pulverized coal supplied to the distributor is set to a preset value. A method for controlling the injection of pulverized coal into a blast furnace, wherein the supply amount of the pressurizing gas to the injection tank is controlled.
Means (2) is a method for controlling pulverized coal injection into a blast furnace according to means (1), characterized in that the supply amount of the gas for pressurization is made equal for each injection tank.
The means (3) is composed of three or more injection tanks for storing pulverized coal for blast furnace injection, and supply pipes that connect the respective injection tanks and the distributor to one in the middle and connect two or more While supplying gas to the injection tank and pressurizing, the pulverized coal in each of the injection tanks is supplied to the distributor through the supply pipe together with the gas, and the supplied pulverized coal is supplied from the distributor to the blast furnace. In the pulverized coal injection control device to the blast furnace, the total amount of pulverized coal injection from each injection tank is calculated based on the change in weight over time measured by the weight measuring device provided in each injection tank. The correction flow rate of the pulverized coal injection amount is obtained based on the difference between the total amount of pulverized coal injection and a preset set injection amount, and the correction flow rate, the preset set injection amount, and the number of injection tanks are calculated. Blowing amount to calculate the supply amount for each blowing tank And a control unit for calculating the flow rate of the pressurizing gas supplied to each of the injection tanks based on the injection amount of each of the injection tanks calculated by the control unit. Is a control device for injecting pulverized coal into a blast furnace.

According to the present invention, it is possible to reliably supply pulverized coal from each of the blowing tanks blowing in parallel to the distributor, so that the single blowing phenomenon is eliminated and the switching cycle of each blowing tank is greatly changed. Since it is possible to control the injection of pulverized coal without having to do so, stable blast furnace operation can be continued.
In addition, by equalizing the control amount of the pressurizing gas in the tank during blowing, the amount of pulverized coal supplied from each blowing tank to the distributor is also equalized, and the switching cycle of each blowing tank is further stabilized. This is preferable.

  As a result of various investigations to suppress the one-side blowing, the present inventors closed, for example, without adjusting the exhaust pressure valve 5a provided in the exhaust pressure piping 5 of the blowing tank performing the blowing. If it is left as it is, when there is a difference in the amount of pulverized coal injected between the two tanks, the pressures in the two injection tanks change so as to correct the difference. That is, in the blowing tank on the side where the amount of pulverized coal increased, the amount of gas in the tank flowing out through the supply pipe 4 also increases, and the internal pressure gradually decreases. In contrast, in the blowing tank on the side where the ratio of the blowing amount decreases, the gas in the tank flowing out through the supply pipe 4 decreases and the internal pressure gradually increases. As a result, it was found that a phenomenon in which the amount of differential coal infused increases gradually along with this.

The inventors further studied a control method for making the most of this phenomenon.
For this purpose, it is necessary not to perform the adjustment operation of the gas amount supplied from the gas supply pipe 3 to the two blowing tanks as much as possible without adversely affecting the operation of the blast furnace.
As this method, even if the pulverized coal outflow amount from each of the injection tanks is different, if the total outflow pulverized coal amount from both the injection tanks maintains the target value required by the blast furnace, It has been found that the operation of adjusting the amount of gas supplied to the two blowing tanks can be greatly reduced without adversely affecting the operation of the blast furnace.
This makes it possible to stabilize the pressure balance at the merging part where the pulverized coal from both blowing tanks merges, and overshoot due to dead time such as measurement of the amount of pulverized coal injection and valve operation. It is possible to significantly suppress the occurrence of a large difference in the amount of blowing between the two blowing tanks that causes the one blowing.

An embodiment of this control method will be specifically described with reference to FIG.
The pulverized coal in each of the injection tanks 2-1 to 2-4 is supplied to the disperser 1 through the supply pipes 4 provided with the injection valves 9-1 to 9-4, and Compressed air is added to the disperser 1 and blown into the blast furnace 7 through the distributor 6 and the tuyere 8 of the blast furnace 7 in sequence.
And control of each blowing tank 2-1 to 2-4 is performed by the common blowing amount control part 15 and the blowing amount control calculating part 12 provided for each blowing tank 2-1 to 2-4 separately. It is. One blowing amount control calculation unit can be provided for each of the blowing tanks 2-1 to 2-4, but this blowing amount control calculation unit 12 is provided for each of the blowing tanks 2-1 to 2-4. Therefore, since the calibration curve (formula or table for converting the pulverized coal flow rate into the pressurized gas flow rate) is slightly different in the system of each of the blowing tanks 2-1 to 2-4, to enable accurate control. It is.
Hereinafter, the blow amount control calculation unit 12 and the common blow amount control unit 15 when pulverized coal is blown into the blast furnace 7 from the blow tanks 2-1 and 2-2 will be described.

In the common blowing amount control unit 15, 17 is a blowing amount calculation unit, and the weight measured by the load cells 10-1 to 10-4 provided separately for the respective blowing tanks 2-1 to 2-4 (of pulverized coal Information on the remaining amount) is input, and the amount of pulverized coal injection (discharge amount) Q1 to Q4 from each of the injection tanks 2-1 to 2-4 is calculated from the time variation of the input weight W. .
The blowing amount adding unit 18 inputs the pulverized coal blowing amounts Q1 to Q4 calculated by the blowing amount calculating unit 17 and obtains the sum, so that the actual value of the pulverized coal amount actually supplied to the blast furnace 7 is obtained. For example, when pulverized coal is supplied to the blast furnace 7 from the blowing tanks 2-1 and 2-2, the blowing tank 2-1 obtained by the blowing amount calculating unit 17 A sum Qtotal (= Q1 + Q2) of 2-2 pulverized coal injection amounts Q1 and Q2 is obtained.
The corrected flow rate calculation unit 16 compares the pulverized coal setting injection amount Q0 from the injection amount setting unit 13 with the sum Qtotal (= Q1 + Q2) of the pulverized coal injection amount obtained by the injection amount calculation unit 18. The difference ΔQ is obtained. The pulverized coal supply amount calculation unit 22 adds (Q0 + ΔQ) the difference ΔQ and the pulverized coal set blowing amount Q0 from the blowing amount setting unit 13 to obtain an added flow rate, and the amount for one blowing tank. In order to make the injection amount 1/2 times (when two injection tanks are used), the pulverized coal injection amount of each of the injection tanks 2-1 and 2-2 is calculated, and this calculated value is It outputs to the blowing control calculating part 12 (only the blowing amount control calculating part of the blowing tank 2-1 is shown) provided in each of the blowing tanks 2-1 and 2-2. In addition, when N blowing tanks are used, 1 / N times the additional flow rate.

Reference numeral 14 denotes a pressurization gas control calculation unit provided in each injection amount control calculation unit 12 for the injection tank 2-1, and the previously input additional flow rate (Q0 + ΔQ) / 2 is stored in advance as “solid flow rate—gas. The pressurization gas flow rate V is obtained from the “flow rate” calibration curve (which converts the pulverized coal flow rate to the pressurization gas flow rate), and is output to the regulator 19.
The regulator 19 adjusts the opening degree of the pressurized flow regulating valve 3a provided in the pressurized gas supply pipe 3 to control the supply of the pressurized gas (pressurized gas).
At this time, the exhaust pressure valve 5a provided in the exhaust pressure pipe 5 is closed or removed.
In the present invention, the gas supply amount can be easily controlled by controlling the gas supply amount to each of the injection tanks based on the total discharge amount of pulverized coal in the injection tank supplied with the gas. I can do it. For example, the gas supply amount can be easily controlled by making the gas supply amounts to the plurality of blowing tanks equal.
And compared with the case where the gas supply amount to each blowing tank is controlled, by controlling the gas supply amount collectively for a plurality of blowing tanks, the pulverized coal discharge control in each blowing tank It is no longer necessary to perform the operation, and the operation of the blast furnace is not adversely affected as described above.

_{Explanatory drawing which shows the blowing amount control method from the blowing tank in this invention} Explanatory drawing which shows the blowing amount control method from the conventional blowing tank

Explanation of symbols

1: Disperser 2-1 to 2-4: Blowing tank 3: Gas supply pipe 4: Supply pipe 5: Exhaust pressure pipe 6: Distributor 7: Blast furnace 10-1 to 10-4: Load cell 12: Blowing amount Control calculation unit 15: Blowing amount control unit 22: Supply amount calculation unit

Claims (3)

Connect three or more injection tanks for storing pulverized coal for blast furnace injection, and supply pipes that connect each of the injection tanks and the distributor to one in the middle. Gas is supplied to two or more injection tanks. While supplying and pressurizing, the pulverized coal in each blowing tank is supplied to the distributor through the supply pipe together with the gas, and the supplied pulverized coal is blown into the blast furnace from the distributor into the blast furnace. In the blowing method,
A method for controlling the injection of pulverized coal into a blast furnace, wherein the supply amount of the pressurizing gas to each of the injection tanks is controlled so that the amount of pulverized coal supplied to the distributor becomes a preset value. .   2. The method for controlling the injection of pulverized coal into a blast furnace according to claim 1, wherein the supply amount of the gas for pressurization is made equal for each of the injection tanks. Connect three or more injection tanks for storing pulverized coal for blast furnace injection, and supply pipes that connect each of the injection tanks and the distributor to one in the middle. Gas is supplied to two or more injection tanks. While supplying and pressurizing, the pulverized coal in each blowing tank is supplied to the distributor through the supply pipe together with the gas, and the supplied pulverized coal is blown into the blast furnace from the distributor into the blast furnace. In the charcoal injection control device,
The total amount of pulverized coal injection from each injection tank is calculated based on the change in weight over time measured by the weight measuring device provided in each of the injection tanks, and this pulverized coal injection total amount is set in advance. Blow in which the correction flow rate of the pulverized coal injection amount is obtained based on the difference in the injection amount, and the supply amount for each injection tank is calculated from the corrected flow rate, the preset injection amount and the number of injection tanks. An amount control unit, and a blowing amount control calculation unit that calculates the flow rate of the pressurizing gas supplied to each blowing tank based on the blowing amount of each blowing tank calculated by the blowing amount control unit A control device for injecting pulverized coal into a blast furnace.

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