JP3788110B2 - Method and apparatus for supplying pulverized coal from intermediate tank to blast furnace in blast furnace pulverized coal injection facility - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to pulverized powder in a blast furnace pulverized coal blowing facility that supplies pulverized coal from a pulverized coal hopper (PC hopper) in a normal pressure state to a high pressure blowing tank via an intermediate tank that can be switched between normal pressure and high pressure. The present invention relates to a charcoal supply method and apparatus.
[0002]
[Prior art]
The operation of injecting a large amount of pulverized coal into the blast furnace is important not only for reducing energy costs, but also for coke oven aging. For this reason, while reducing the coke ratio charged from the top of the furnace, we are actively working to increase the ratio of pulverized coal (PC ratio) blown into the furnace together with hot air from the tuyere. In order to continue stable PC ratio operation, pulverized coal in the PC hopper is blown in via an intermediate tank, and a stable amount of pulverized coal is maintained from the tank to the blast furnace without fluctuation. Is important.
[0003]
In general, as shown in FIG. 2, during operation of the blast furnace 20, hot air is blown into the furnace from the tuyere 23 via the annular pipe 22 and the blow pipe 21 that surround the lower part of the blast furnace 20. At this time, the pulverized coal in the blowing tank 5 is supplied into the tuyere 23 disposed at the lower portion of the blast furnace 20 via the pulverized coal supply pipe 19 at a predetermined PC ratio, and is blown into the furnace together with hot air. Since the amount of pulverized coal in the blowing tank 5 is gradually reduced by blowing the pulverized coal into the blast furnace 20, the pulverized coal in the pulverized coal hopper 1 is supplied to the blowing tank 5 via the intermediate tank 4 at an appropriate timing. .
[0004]
Coal blown into the blast furnace 20 is collected by pulverized coal produced by pulverization using a pulverizer and stored in the PC hopper 1. While the PC hopper 1 is in the normal pressure state, the furnace pressure in the lower part of the blast furnace is about 4 to 5 kg / cm ^2, so that the inside of the blowing tank 5 is at a high pressure of about 7 kg / cm ² . In order to supply pulverized coal from the PC hopper 1 in the normal pressure state to the intermediate tank 4, first the pulverized coal in the PC hopper 1 is supplied to the intermediate tank 4 with normal pressure in the intermediate tank 4, and then in the intermediate tank 4. The operation of pressurizing to high pressure and supplying the pulverized coal in the intermediate tank 4 to the blowing tank 5 in a high pressure state is repeated.
[0005]
That is, the pulverized coal stored in the PC hopper 1 in the normal pressure state is supplied to the intermediate tank 4 under the normal pressure state by opening the pulverized coal supply valve 3 provided in the pulverized coal supply pipe 2. At this time, the regulating valve 7 and the pulverized coal supply valve 8 provided in the pulverized coal supply pipe 6 that connects the intermediate tank 4 and the blowing tank 5, the pressure equalizing pipe 9 that connects the upper part of the intermediate tank 4 and the upper part of the blowing tank 5. The pressure equalizing valve 10 provided in the above, the shutoff valve 12 provided in the nitrogen gas supply pipe 11, the control valve 13, and the small exhaust valve 15 provided in parallel on the exhaust pipe 14 connected to the upper part of the intermediate tank 4 are closed, The large exhaust valve 16 is open.
[0006]
When a predetermined amount of pulverized coal is supplied from the PC hopper 1 to the intermediate tank 4, the pulverized coal supply valve 3 and the large exhaust valve 16 are closed, then the shutoff valve 12 is opened and the opening of the control valve 13 is adjusted to adjust nitrogen. High-pressure nitrogen gas is supplied from the gas supply pipe 11 to the nitrogen gas generator 24 provided at the lower part of the intermediate tank 4 to pressurize the intermediate tank 4. As shown in FIG. 3, the nitrogen gasator 24 provided at the lower part of the intermediate tank 4 is disposed inside the perforated plate 26 provided with a large number of holes of about 15 mmφ provided inside the blowing box 25 connected to the lower part of the intermediate tank 4. A structure in which a breathable canvas 27 is set, the nitrogen gas blown into the blower box 25 from the nitrogen gas supply pipe 11 is passed through the porous plate 26 and the breathable canvas 27, and the pulverized coal in the intermediate tank 4 is floated. By liquefying nitrogen gasation, pulverized coal is blown into the tank 5 smoothly using nitrogen gas as a carrier gas.
[0007]
When the pressure in the intermediate tank 4 becomes a high pressure close to the nitrogen gas pressure in the blowing tank 5 and the pulverized coal in the blowing tank 5 is reduced by blowing the pulverized coal into the blast furnace 20, the nitrogen gas supply pipe 11 The pulverized coal is fluidized by nitrogen gas supplied into the intermediate tank 4 and the blast coal tank is blown from the intermediate tank 4 through the pulverized coal supply pipe 6 by opening the pulverized coal supply valve 8 and adjusting the opening of the control valve 7. 5 is supplied with pulverized coal. At this time, the pressure equalizing valve 10 is opened to equalize the pressure in the intermediate tank 4 and the blowing tank 5 and a part of the nitrogen gas supplied into the blowing tank 5 passes through the pressure equalizing pipe 9 and the upper part of the intermediate tank 4. And is exhausted from the PC hopper 1 through the small exhaust valve 15 and the exhaust pipe 14 to the outside of the system.
[0008]
[Problems to be solved by the invention]
According to the prior art, in the stage of replenishing pulverized coal from the intermediate tank 4 through the pulverized coal supply pipe 6, the intermediate tank 4 is blown into the intermediate tank 4 through the nitrogen gas supply 24 from the nitrogen gas supply pipe 11. However, pulverized coal was often blown with nitrogen gas and could not be transported to the tank 5 side. For this reason, the supply speed of the pulverized coal is merely supplied to the blowing tank 5 by the gravity of the pulverized coal and slight nitrogen gasation, and the supply speed is small, the flow of nitrogen gas is indefinite, and the pulverized coal is deposited. When the bridge is generated, the dispersion of the pulverized coal supply rate becomes large and finally it becomes uncontrollable, which has been a bottleneck in the operation of blast furnace pulverized coal injection.
[0009]
When the pulverized coal forms a bridge and is suspended in the intermediate tank 4, the nitrogen gas blown into the intermediate tank 4 through the nitrogen gasator 24 escapes upward along the wall as indicated by the arrow A, A phenomenon occurs in which the gas reaches the upper part of the tank 4 and is discharged from the PC hopper 1 through the small exhaust valve 15 to the outside of the system. As a result, the pulverized coal significantly reduces the supply speed from the intermediate tank 4 to the blowing tank 5 or is not supplied at all.
[0010]
By the way, the supply from the intermediate tank 4 to the blowing tank 5 via the pulverized coal supply pipe 6 by nitrogen gasation has difficulty depending on the coal type of the pulverized coal. The properties of pulverized coal vary widely, from those with a low repose angle when depositing (good fluidity) to those with a high repose angle and high repose angle (poor fluidity). A pulverized coal with low fluidity and good fluidity could be handled by conventional techniques. However, when using pulverized coal with high viscosity and poor fluidity, a shelf hanging phenomenon derived from the properties of the pulverized coal occurs during the supply of pulverized coal from the intermediate tank to the blowing tank. Cost and high cost.
[0011]
For example, FIG. 4 shows a change in the weight of the intermediate tank in the process of supplying the pulverized coal having poor fluidity from the intermediate tank 4 to the blowing tank 5 according to the conventional example. At the stage indicated by line A, the weight of the pulverized coal is steadily decreasing and the supply speed is large. However, at the stage indicated by the line B after that, the weight reduction of the pulverized coal is small and the supply speed is rapidly reduced. If the replenishment rate of pulverized coal is unstable and rapidly decreases in this way, there is a risk that the supply time will exceed the scheduled time and there will be a risk that the remaining amount of pulverized coal in the blowing tank 5 will disappear. Measures such as reducing the blowing of charcoal will be required, which will adversely affect blast furnace operation.
[0012]
The present invention is the solve the prior art problems, the supply of fine powdered coal to the tank blown from the intermediate tank is always possible stably supplied without being influenced by the type of coal, and the feed rate of pulverized coal An object of the present invention is to provide a method and an apparatus for supplying pulverized coal from an intermediate tank to an injection tank in a blast furnace pulverized coal injection facility that can be significantly increased.
[0013]
[Means for Solving the Problems]
When the conventional technique shown in FIG. 2 is used, the cause of the unstable and unstable pulverized coal supply rate from the intermediate tank 4 to the blowing tank 5 was examined. Knowledge that the pressure action and the exhaust action by the small exhaust valve 15 disposed in the exhaust pipe 14 connected to the upper part of the intermediate tank 4 hinder the one-way flow of nitrogen gas from the intermediate tank 4 to the blowing tank 5 did. In other words, the pressure condition between the two tanks [pressure of the intermediate tank 4> pressure of the blowing tank 5] necessary for the pressure equalizing pipe 9 and the exhaust pipe 14 to ensure one-way flow of nitrogen gas is [pressure of the intermediate tank 4 < The pressure of the blowing tank 5 is easily reversed.
[0014]
The present invention has been made based on the above findings, and has been achieved by removing the pressure equalizing pipe, which has been considered necessary from the past, and by fundamentally reviewing the connection position of the exhaust pipe. is there.
In order to achieve the above object, the present invention according to claim 1 is a method for supplying pulverized coal from an intermediate tank to a blowing tank in a blast furnace pulverized coal blowing facility, wherein high-pressure nitrogen is supplied via a nitrogen gasator provided at a lower portion of the intermediate tank. A small exhaust valve disposed in an exhaust pipe connected to the upper part of the blowing tank, while blowing gas, pressurizing the interior of the intermediate tank from normal pressure to high pressure and supplying pulverized coal to the blowing tank with nitrogen gas. By adjusting the opening and discharging part of the high-pressure nitrogen gas in the blowing tank out of the system, the inside of the blowing tank is made lower than in the intermediate tank, and the unidirectional flow of nitrogen gas is maintained to maintain the pulverized coal A method for supplying pulverized coal from an intermediate tank to an injection tank in a blast furnace pulverized coal injection facility characterized in that a supply speed is maintained at a target value.
[0015]
According to a second aspect of the present invention, pulverized coal is supplied to the blowing tank by supplying high-pressure nitrogen gas from a pressurized pipe connected to the middle and / or upper part of the intermediate tank and increasing the pressure of the intermediate tank. The pulverized coal supply method from the intermediate tank to the injection tank in the blast furnace pulverized coal injection facility according to claim 1, wherein the supply rate of the blast furnace is increased.
[0016]
According to a third aspect of the present invention, in the apparatus for supplying pulverized coal from an intermediate tank to an injection tank in a blast furnace pulverized coal injection facility, the interior of the intermediate tank is pressurized from normal pressure to high pressure at the lower part of the intermediate tank and pulverized coal. A nitrogen gasator is provided for nitrogen gasation, while an exhaust pipe is connected to the upper part of the blowing tank, and a small exhaust valve with an adjustable opening is arranged in the exhaust pipe to discharge the high-pressure nitrogen gas in the blowing tank out of the system. A pulverized coal supply device from an intermediate tank to a blowing tank in a blast furnace pulverized coal blowing facility characterized by being provided.
[0017]
According to a fourth aspect of the present invention, a high-pressure nitrogen gas is supplied to the middle and / or upper part of the intermediate tank to connect a pressure pipe for increasing the pressure of the intermediate tank. The apparatus for supplying pulverized coal from an intermediate tank to an injection tank in a blast furnace pulverized coal injection facility according to claim 3, further comprising a control valve for adjusting an amount of nitrogen gas supplied.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, when hot air is blown from a tuyere 23 through an annular pipe 22 surrounding a lower part of a blast furnace 20 through a blow pipe 21, the pulverized coal in the blowing tank 5 is supplied with nitrogen gas. By adjusting the opening of the control valve 18 with the shutoff valve 17 provided in the pipe 11 open, the high-pressure nitrogen gas blown into the blow-in tank 5 is passed through the pulverized coal supply pipe 19 and is disposed in the lower part of the blast furnace 20 It is supplied into the mouth 23 and blown into the furnace together with hot air.
[0019]
When supplying the pulverized coal stored in the PC hopper 1 at normal pressure to the intermediate tank 4, the large exhaust valve 16 is opened, and the nitrogen gas in the intermediate tank 4 is passed through the exhaust pipe 14 to the PC hopper 1. Then, the inside of the intermediate tank 4 is returned to normal pressure by discharging it out of the system. Next, the pulverized coal supply valve 3 provided in the pulverized coal supply pipe 2 is opened, and the pulverized coal is supplied from the PC hopper 1 to the intermediate tank 4 under normal pressure. At this time, the control valve 7 provided in the pulverized coal supply pipe 6 connecting the intermediate tank 4 and the blowing tank 5, the shut-off valve 12 provided in the nitrogen gas supply pipe 11, the control valve 13, and the exhaust pipe The small exhaust valve 15 and the switching valve 28 provided in 14 are closed, and the large exhaust valve 16 remains open. When a predetermined amount of pulverized coal is supplied from the PC hopper 1 to the intermediate tank 4, the pulverized coal supply valve 3 and the large exhaust valve 16 are closed.
[0020]
At the stage when pulverized coal needs to be refilled into the blast furnace 20 due to the blast furnace 20 being blown into the blast furnace 20, the shut-off valve 12 is opened and the opening of the control valve 13 is adjusted so that the nitrogen gas supply pipe 11 High-pressure nitrogen gas is supplied to a nitrogen gasator 24 provided at the lower part of the intermediate tank 4 to pressurize the inside of the intermediate tank 4. Thereafter, the fine coal in the intermediate tank 4 is nitrogen gasated and fluidized, and then supplied to the blowing tank 5 side. At this time, high-pressure nitrogen gas is introduced into the intermediate tank 4 using the pressurized pipe 29 connected to the middle and upper part of the intermediate tank 4 to promote gasation therein. This not only facilitates pressurization in the intermediate tank 4 to a pressure higher than that in the blowing tank 5, but also increases the amount of nitrogen gas from the intermediate tank 4 to the blowing tank 5. The speed at which the fine coal is blown from the intermediate tank 4 to the tank 5 can be increased. As described above, the nitrogen gasator 24 provided at the lower part of the intermediate tank 4 comprises a blowing box 25 connected to the lower part of the intermediate tank 4, a perforated plate 26 provided inside, and a breathable canvas 27 set inside thereof. (See FIG. 3).
[0021]
As described above, the pulverized coal is fluidized by the nitrogen gas supply supplied into the intermediate tank 4 from the nitrogen gas supply pipes 11 and 29, while the pulverized coal supply valve 8 is opened and the opening of the control valve 7 is adjusted. The pulverized coal is supplied from the tank 4 to the blowing tank 5 through the pulverized coal supply pipe 6.
Figure 6 is in the N ₂ gas Configuration ^{MAX = 26Nm 3 / min (100} %) based on the conventional ^{equipment, A 18 Nm 3 / min (} 70%) of N ₂ gas flow rate, B and the N ₂ gas flow rate In the case of 22 Nm ³ / min (85%), C is N ₂ gas flow rate of 38 Nm ³ / min (100%) based on N ₂ gasation MAX = 30 Nm ³ / min (100%) in the conventional equipment. PC feed rate test results in the case where 127%), i.e. shows the relationship between the N ₂ gas configuration flow in the case of increasing or decreasing the N ₂ gas configuration flow rate (%) and PC feed rate (t / min) by the present invention ing. As shown in FIG. 6, the N ₂ gasation flow rate (%) and the PC supply rate (t / min) have a direct proportional relationship as shown by the straight line D, and the PC supply rate can be easily increased or decreased by increasing or decreasing the nitrogen gasation. Can be adjusted to. At the same time, by using both supply pipes 11 and 29 at the same time, it is possible to increase to 38 Nm ³ / min (127%) compared to the conventional N ₂ gasation MAX = 30 Nm ³ / min (100%). The PC supply rate was increased from 2.2 t / min to 2.6 t / min, and the pulverized coal supply time was reduced from 13 minutes to 10.5 minutes.
[0022]
According to the present invention, in the process of supplying pulverized coal from the intermediate tank 4 to the blowing tank 5, the pulverized coal is affected by the properties such as adhesiveness by the nitrogen gas blown into the intermediate tank 4 through the nitrogen gasator 24. It is fully fluidized without being blown, and the intermediate tank 4 can be stably maintained at a high pressure from the inside of the blowing tank 5, and nitrogen gas can flow stably in one direction without causing troubles such as shelf hanging. The pulverized coal can be supplied to the blowing tank 5 at a constant supply speed. Moreover, it is easy to increase the supply speed of pulverized coal as required, and the operation of blowing pulverized coal in the blast furnace can be performed stably with a desired PC ratio.
[0023]
For example, FIG. 5 shows the change in the weight of the intermediate tank in the process of supplying pulverized coal with poor fluidity from the intermediate tank 4 to the blowing tank 5 according to the present invention. The pulverized coal can be supplied at a constant supply rate as indicated by a line C indicating the change in weight until the end of 14 minutes. Since the supply speed of pulverized coal is constant and stable in this way, it can be supplied in a short time, the remaining amount of pulverized coal in the injection tank 5 is not interrupted, and the pulverized coal injection into the blast furnace 20 is in a steady state. The blast furnace operation with a high PC ratio can be achieved.
[0024]
【The invention's effect】
As described above, according to the present invention, the inside of the intermediate tank is pressurized from normal pressure to high pressure, and the pulverized coal is nitrogen-gasified and supplied to the blowing tank, and is disposed in the exhaust pipe connected to the upper part of the blowing tank. It is possible to maintain a one-way flow of nitrogen gas from the intermediate tank into the blowing tank by adjusting the opening of the small exhaust valve and discharging the high-pressure nitrogen gas in the blowing tank out of the system. is there. Because the pulverized coal supply rate can be constantly and constantly injected in large quantities without depending on a wide variety of pulverized coal brands, it is possible to supply in a short time, and the operation with the high PC ratio of the blast furnace is stabilized, reducing costs. Achieved.
[Brief description of the drawings]
FIG. 1 is a flow diagram showing an apparatus for supplying pulverized coal from an intermediate tank to a blowing tank in a blast furnace according to the present invention.
FIG. 2 is a flow diagram showing an apparatus for supplying pulverized coal from an intermediate tank to a blowing tank in a conventional blast furnace.
FIG. 3 is a cross-sectional view showing a nitrogen gasator provided in the lower part of the intermediate tank.
FIG. 4 is a graph showing the time transition of the intermediate tank weight in the conventional example.
FIG. 5 is a graph showing the time transition of the intermediate tank weight of the example of the present invention.
FIG. 6 is a graph showing the relationship between N ₂ gasation flow rate (%) and PC supply rate (t / min).
[Explanation of symbols]
1 Pulverized coal hopper (PC hopper)
2, 6, 19 Pulverized coal supply pipe 3, 8 Pulverized coal supply valve 4 Intermediate tank 5 Blowing tank 7, 13, 18, 31 Control valve 9 Pressure equalizing pipe
10 Pressure equalizing valve
11 Nitrogen gas supply pipe
12, 17, 30 Shut-off valve
14 Exhaust pipe
15 Small exhaust valve
16 Large exhaust valve
20 Blast furnace
21 Blow pipe
22 Annular pipe
23 tuyere
24 Nitrogen gasrator
25 Blow box
26 Perforated plate
27 Breathable canvas
28 Switching valve
29 Pressurized piping

Claims (4)

In the method of supplying pulverized coal from an intermediate tank to a blast furnace in a blast furnace pulverized coal injection facility, high pressure nitrogen gas is injected through a nitrogen gasator provided at the lower part of the intermediate tank, and the inside of the intermediate tank is pressurized from normal pressure to high pressure. A part of the high-pressure nitrogen gas in the blowing tank by adjusting the opening of a small exhaust valve disposed in the exhaust pipe connected to the upper part of the blowing tank The blast furnace pulverized coal is characterized in that the inside of the blowing tank is made to be at a lower pressure than that in the intermediate tank, and the unidirectional flow of nitrogen gas is maintained to maintain the supply speed of the pulverized coal at a target value. A method for supplying pulverized coal from an intermediate tank to a blowing tank in a blowing facility. A high-pressure nitrogen gas is supplied from a pressurized pipe connected to the middle and / or upper part of the intermediate tank, and the pressure of the intermediate tank is increased to increase the supply speed of pulverized coal to the blowing tank. The method for supplying pulverized coal from the intermediate tank to the injection tank in the blast furnace pulverized coal injection facility according to claim 1. In the apparatus for supplying pulverized coal from an intermediate tank to an injection tank in a blast furnace pulverized coal injection facility, a nitrogen gas generator is provided below the intermediate tank to pressurize the intermediate tank from normal pressure to high pressure and to perform nitrogen gasation of the pulverized coal. On the other hand, a blast furnace fine powder characterized in that an exhaust pipe is connected to an upper part of the blowing tank, and a small exhaust valve capable of adjusting the opening is provided in the exhaust pipe to discharge high-pressure nitrogen gas in the blowing tank out of the system. Equipment for supplying pulverized coal from an intermediate tank to a blowing tank in a coal blowing facility. An adjustment for supplying high-pressure nitrogen gas to the middle and / or upper part of the intermediate tank to connect a pressure pipe for increasing the pressure of the intermediate tank, and adjusting the supply amount of the high-pressure nitrogen gas to the pressure pipe The apparatus for supplying pulverized coal from the intermediate tank to the injection tank in the blast furnace pulverized coal injection facility according to claim 3, wherein a valve is provided.

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