JPH08295911A - Method for blowing pulverized coal - Google Patents

Abstract

PURPOSE: To smoothly execute the change-over of blowing tanks while holding the balance of blowing flow rate by gradually closing a blowing control value for a blowing tank to a regulating opening degree at the time of judging the completion of blowing and at the same time, gradually opening a control value for a blowing tank under waiting to a regulating opening degree. CONSTITUTION: The blowing from the blowing tank 1-1 processes and the weighing value from a weighing device 3-1 becomes the regulating value or lower, and at the time of judging the completion of blowing the blowing control value 7B-1 is gradually closed to the regulated opening degree with a flow rate controller 6-1. Further, a cutoff valve 2A-2 is opened and the blowing control valve 7B-2 is gradually opened according to the blowing flow rate with a flow rate controller 6-2. At this time, since the blowing tans 1-1, 1-2 are controlled to almost the same pressure, the pressure variation in the blowing tanks and a carrying pipe 8 and the blowing flow rate variation caused by the start of closing the blowing control valve 7B-1 and the start of opening the blowing control valve 7B-2 are made to the min. limit. Successively, a blowing cutoff valve 2A-1 and the blowing control valve 7B-1 are fully closed and the blowing cutoff valve 2A-2 and the blowing control valve 7B-2 are fully opened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for continuously injecting fine coal or fine ore into a blast furnace.

[0002]

2. Description of the Related Art In FIG. 2, pulverized coal injection tanks 1-1 and 1-2 arranged in parallel are alternately filled with pulverized coal, pressurized in the tank, injected pulverized coal, and exhausted in the tank. Pulverized coal is continuously blown into the blast furnace. Blow off valve 2A when blowing
-1, 2B-1 or 2A-2, 2B-2 are opened, and the pulverized coal is pressure-fed to the carrier pipe 8 and mixed with carrier gas to be conveyed and blown into the blast furnace. The amount of pulverized coal blown is controlled by the blown amount adjuster 6-
1, 6-2 receives the weight signal from the weighing devices 3-1, 3-2 and the pressure signal from the pressure gauges 4-1, 4-2, and after calculation, in the pulverized coal injection tank 1-1 or 1-2. The pressure is controlled by adjusting pressures of the pressure control valves 5-1 and 5-2.

Now, the pulverized coal injection tank 1-1 is injecting,
Further, in 1-2, it is assumed that the filling and pressurization has been completed and is waiting.
At this time, the blowoff shutoff valves 2A-1 and 2B-1 are opened, and 2A
-2, 2B-2 are closed. By blowing pulverized coal,
When the weighed value of the weighing machine 3 decreases and the end of blowing is detected, the blowing shutoff valves 2A-1 and 2B-1 are closed, and the pulverized coal blowing tank 1-1 starts discharging pressure. At the same time, the blowoff valve 2A-2,
2B-2 opens and starts blowing from the pulverized coal blowing tank 1-2. As described above, in the conventional technique, the blow tank is switched by the blow cutoff valve (JP-A-5-13).
No. 07 publication).

[0004]

SUMMARY OF THE INVENTION In the prior art,
When switching the blowing tank, the blowing shutoff valves 2A-1, 2B-1 of the blowing tank being blown are closed, and at the same time, the blowing shutoff valves 2A-2, 2B-2 of the other waiting blowing tank are opened. However, at this moment, the inside of the blowing tank and the inside of the transfer pipe are in an unstable state, and it becomes impossible to control the blowing amount by adjusting the pressure inside the blowing tank for several minutes. Therefore, the flow rate controller 6
-1 and 6-2, during this transition period, the injection tank pressure control is stopped and the opening of the pressure control valves 5-1 and 5-2 are fixed, but during this period, a slight amount during injection into the blast furnace is observed. The flow rate of powder coal fluctuates greatly, which hinders stable blast furnace operation. It is an object of the present invention to provide a pulverized coal blowing method that suppresses such fluctuations in the pulverized coal blowing flow rate at the time of switching the blowing tank and enables stable blast furnace operation.

[0005]

According to the present invention, a plurality of pulverized coal injection tanks are arranged in parallel, and each pulverized coal injection tank sequentially performs pulverized coal filling, tank pressure, pulverized coal injection, and tank exhaust pressure. In the pulverized coal blowing method in which the pulverized coal is alternately blown into the blast furnace while repeating, when blowing from one pulverized coal blowing tank is completed and switching to another standby blowing tank,
The blowing control valve of the blowing tank during blowing is gradually closed to the specified opening, and at the same time, the blowing control valve of the standby blowing tank is gradually opened according to the blowing flow rate, and the blowing flow rate from each pulverized coal blowing tank is adjusted. The above problem is solved by switching the blowing tank while monitoring.

[0006]

According to the present invention, when the measured value of the blowing tank during blowing becomes equal to or less than the specified value and it is judged that the blowing is completed, the blowing control valve is gradually closed to the specified opening, and at the same time, the blowing tank in the standby state is blown. The control valve can be gradually opened to a specified opening according to the blowing flow rate, and the blowing tanks can be smoothly switched while maintaining the balance of the blowing flow rates from the respective blowing tanks.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIG. Constituent elements that are the same as those in the prior art shown in FIG. 2 are denoted by the same reference numerals and the description thereof will be omitted, and the description will focus on the characteristic portions of the present invention. In FIG. 1, 7B-1 and 7B-2 are injection control valves having a flow rate adjusting function, and are adjusted by the injection control meter 6-1 or 6-2, respectively. 2A
-1 and 2A-2 are blow-off valves for keeping confidentiality when pressurizing the blow-in tank.

Now, it is assumed that the blowing tank 1-1 is being blown and the blowing tank 1-2 has been filled and pressurized and is in a standby state. At this time, the blow-off valve 2A-1, the blow control valve 7B-1
Is open, and the blow-off valve 2A-2 and the blow control valve 7B-2
Is closed. When the blowing from the blowing tank 1-1 progresses, the measured value from the weighing machine 3-1 becomes less than the specified value, and when it is judged that the blowing has ended, the flow rate controller 6-1 causes the blowing control valve 7B-1.
Is gradually closed to the specified opening. Blow off valve 2 at the same time
A-2 is opened, and the flow rate controller 6-2 is the blow control valve 7B-2.
Gradually open according to the blowing flow rate. At this time, since the blow tanks 1-1 and 1-2 are controlled to have substantially the same pressure, the blow control valve 7B-1 starts closing and the blow control valve 7B-.
The pressure fluctuation and the blowing flow rate fluctuation in the blowing tank and the conveying pipe 8 due to the start of opening 2 are minimized. After that, the blow cutoff valve 2A-1 and the blow control valve 7B-1 are fully closed, and the blow cutoff valve 2A-2 and the blow control valve 7B-2 are fully opened to smoothly switch the blow tanks.

FIG. 3 shows an example of opening control of the blowing control valve 7B-1 and the blowing control valve 7B-2 when the specified opening in the process of opening and closing the blowing control valve is 50%. Blow control valve 7B-
The opening of 1 gently closes from 100% to 50%, 5
It will close at 0%. At this time, the blow control valve 7B-2 opens gently from 0% opening and fully opens when it reaches 50%. At this time, the total flow rate is small in both the flow rate fluctuation amount and the flow rate fluctuation period as indicated by 9.

[0010]

According to the present invention, it is possible to suppress a large fluctuation in the amount of pulverized coal injected at the time of switching the conventional blowing tank, and to stabilize the operation of the blast furnace even at the time of switching the blowing tank.

[Brief description of drawings]

FIG. 1 is an explanatory view showing one embodiment of the present invention.

FIG. 2 is an explanatory view showing a conventional pulverized coal blowing device.

FIG. 3 is an explanatory diagram showing an example of control of a blow valve according to the present invention.

[Explanation of symbols]

 1-1, 1-2 Blow tank 2A-1, 2A-2 Blow cutoff valve 2B-1, 2B-2 Blow cutoff valve 3-1, 3-2 Weigher 4-1, 4-2 Blow tank pressure gauge 5 -1, 5-2 Blow tank pressure control valve 6-1, 6-2 Blow flow rate controller 7B-1, 7B-2 Blow control valve 8 Conveyor pipe 9 Total flow rate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Isao Nishikawa 46-59 Nakahara, Tobata-ku, Kitakyushu, Fukuoka 46-59 Nippon Steel Corporation Machinery & Plant Division (72) Ryuji Koga Tobata-ku, Kitakyushu, Fukuoka Nakahara 46-59 Nippon Steel Corporation Machinery & Plant Division

Claims (1)

[Claims] 1. A plurality of pulverized coal blowing tanks are arranged in parallel, and each pulverized coal blowing tank is alternately pulverized into a blast furnace while sequentially repeating pulverized coal filling, tank pressurization, pulverized coal blowing, and tank exhaust pressure. In the pulverized coal blowing method of blowing charcoal,
When blowing from one pulverized coal blowing tank is completed and switching to another waiting blowing tank, gradually close the blowing control valve of the blowing tank being blown to the specified opening, and at the same time blow the waiting blowing tank. A pulverized coal blowing method characterized by gradually opening a control valve according to the blowing flow rate and switching the blowing tank while monitoring the blowing flow rate from each pulverized coal blowing tank.