JPH0159325B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method and apparatus for blowing pulverized coal into a blast furnace such as a blast furnace for iron-making.

(Prior art) With the development of blast furnace technology, liquid fuels such as heavy oil have been used as fuel for injection into blast furnaces.
From the time when the price of heavy oil soared, solid fuels such as pulverized coal, which is made by pulverizing coal, began to be used in place of liquid fuels, and along with this, powder injection technology also developed.

The properties of pulverized coal used as fuel are determined by its particle size.
Most of the particles are less than 250μ, but many of them contain 40% or more of fine powder of 63μ or less, and some have a water content of more than 1.5%.

Furthermore, once pulverized coal contains gas, it flows like a liquid and causes flashing, but if it is left to stand still, it becomes compacted and causes bridging. It has the property of causing intraductal occlusion, which is troublesome for intraductal transportation.

Therefore, a blowing machine for blowing pulverized coal into a blast furnace stores the pulverized coal in a pressure vessel called a blow tank, fluidizes it by blowing gas into it, and adjusts the pressure inside the blow tank appropriately. A method has been used in which the amount of injection is controlled by

The series of relationships in a conventionally used device for blowing pulverized coal into a blast furnace is shown in FIG.

In the figure, X, Y, and Z are the aforementioned blow tank type blowing machines. For example, when X is transporting pulverized coal, Y is already stored with pulverized coal and is on standby, and Z is a storage bunker. Currently receiving pulverized coal from 21. Therefore, in order to blow continuously,
It is used by switching sequentially to X, Y, and Z.

The pulverized coal delivered sequentially from these blow tanks
2, and a multi-manifold distributor 23 is disposed there.

In general, branch pipes 24, 24, . They are connected under various constraints so that the pressure loss is equal.

The reason for this is that the amount of pulverized coal distributed by the distributor 23 is controlled by the pressure and flow rate of the carrier gas sent from the pressure gas source 26, so the pressure drop inside the pipe of the multi-purpose distributor 23 is reduced. If the flow is uneven, the amount of pulverized coal injected at the tuyere will be uneven, and once this uneven flow occurs, the mixed flow of gas and pulverized coal will be biased toward the pipe with less resistance. To go.

Examples of distributors devised to prevent this bias are ``Utility Model Publication No. 41-021135'' and ``Japanese Unexamined Patent Publication No. 52-64780,'' which are shown in Figures 7, 8, and 9. It shows the structure of

(Problem to be solved by the invention) However, the cause of uneven flow in the conduit is not only due to the quality of the distribution device, but there are many hidden factors, but the cause that is most difficult to deal with is the inside of the blast furnace. One is caused by the furnace conditions, and the other is caused by the pulverized coal itself adhering to the inside of the pipe.

The drift caused by these causes eventually develops to the point of clogging the conduit 22 and the branch pipes 24, 24, etc., making it impossible for some of them to transport the pulverized coal.

As shown in FIG.
There is a method in which a secondary distributor 27 is provided and the water is distributed from there to the blast furnace tuyere via a plurality of branch pipes 24, 24, . . . through the distributors 23, 23, . Alternatively, there is also a method in which, for example, 20 branch pipes are taken out directly from the aforementioned blow tank body and connected to the tuyeres of the blast furnace. In the latter case, as already mentioned, the pulverized coal fluidized in the blow tank is
Since the amount is pumped according to the respective pressure, conversely, if the back pressure of the transport source pipe 28 changes,
The amount of carrier gas increases or decreases, and the amount of pulverized coal also changes in proportion to this, and this is the same as in the case of the distributor described above.

Furthermore, the blast furnaces used in Japan range in diameter from about 7 m to 15 m, and the number of tuyeres distributed evenly around the circumference ranges from 16 to 40. Therefore, it is not easy to constantly feed an equal amount of pulverized coal to these devices, and it is therefore difficult to maintain balanced combustion throughout the blast furnace using the above-mentioned device.

Furthermore, if a problem occurs in some of the branch pipes 24, 24... after branching due to blockage in the pipes due to pulverized coal, etc., and if the faulty branch pipes are conduits to mutually adjacent tuyeres, This makes it impossible for combustion to occur in adjacent tuyeres, causing a thermal imbalance in uneven parts of the blast furnace, making stable operation impossible.

In addition, since the conventionally used blow tank type blower increases or decreases the amount of pulverized coal supplied by changing the gas pressure in the tank, pressure drop changes in the conduit 22 and branch pipes 24, 24, etc. When there is a change in the pressure in tanks
There are problems such as changes in the amount of pulverized coal supplied to Y and Z, which is undesirable.

(Means for Solving the Problems) The present invention provides a fuel injection system that makes it easy to maintain thermal stability in a blast furnace even though the injection device has unavoidable problems as described above. The present invention provides a method for supplying pulverized coal from a storage pressure vessel into a blast furnace by force-feeding it with pressurized gas, the pulverized coal in the storage pressure vessel being volumetrically metered. A distributor is provided at one end of a conduit connected to each of the plurality of discharge ports arranged in a row in the feeder, and a pair of branches branched from each distributor are used to supply the cut material by pneumatically supplying it with pressurized gas. A fine powder characterized in that branch pipes are uniformly supplied into a blast furnace through distribution piping connected to a plurality of tuyeres provided at the periphery of the blast furnace, each of which is located opposite to the center of the blast furnace. A method for blowing coal; and a volumetric feeder, which is driven by a variable speed motor and discharges an equal amount of pulverized coal from a plurality of outlets, at the bottom of a pulverized coal storage pressure vessel to accomplish the above method. A plurality of blades are arranged in series, a conduit is connected to each of the discharge ports, a distributor is provided at the tip of each conduit to branch a pair of branch pipes, and each pair of branch pipes is connected to a plurality of blades provided at the peripheral edge of the blast furnace. This constitutes a blowing device that communicates with the tuyere located opposite to the center of the blast furnace.

The structure and operation of the present invention will be explained in FIGS. 1 to 4 below.
This will be explained using the embodiment shown in the figures. Storage pressure vessel 2 (hereinafter referred to as tank 2) having a pulverized coal receiving valve 1 at the top
At the bottom of the rotor 3, there are weighing squares 4, 4 on the outer periphery of a rotor 3 which is rotated horizontally by a variable speed motor M.
...... are arranged in succession, and an appropriate number (corresponding to 1/2 of the number of tuyere of the blast furnace, the number of tuyere is 18 in the figure) is provided on the bottom wall.
5a, 5b...5i
A volumetric feeder 7 having shielding plates 6, 6, . In addition to being able to supply the pressure gas necessary to transport the pulverized coal in the tank 2 and inject it from the tuyere of the blast furnace B, the pressure equalizing pipe 10, which is a branch of the gas introduction pipe 9 outside the feeder 7, is connected to the tank. The upper space pressure of the pulverized coal in the tank 2 is controlled by the pressure gas supplied from the pressure equalization pipe 10, and the discharge of the feeder 7 by the pressure gas supplied from the gas introduction pipe 9. Exits 5a, 5b...
By always equalizing the pressure in section 5i, that is, the pressure at the top and bottom of the pulverized coal bed, even if pressure fluctuations occur in the blowing pipe to the tuyere or the pressure in tank 2 changes, the pressure in the blast furnace B remains constant. When the amount of pulverized coal supplied under atmospheric pressure is maintained at almost the same constant level.

Conduits 11a, 11b...11i are connected to the discharge ports 5a, 5b...5i of the feeder 7, respectively, and the tips of the conduits are connected to bifurcated distributors 12a, 12b...12.
i, and each distributor 12a, 12b...12i
A pair of branch pipes 13a, 13a', 13 from each of
b, 13b'...13i, 13i' are branched, and each pair of branch pipes 13a, 13a', 13b, 13b'...1
Tuyeres 14a, 14a', 14b, 1 are provided at the periphery of the blast furnace B with the tuyeres 3i, 13i' facing away from the center of the blast furnace.
4b'...14i, 14i' constitutes the apparatus A of the present invention connected to the tank 2 of the apparatus A, and the pulverized coal supplied into the tank 2 from the pulverized coal receiving valve 1 is injected from the pressure gas source 8. The pulverized coal distributed in fixed quantities in the feeder 7 by pressure gas is discharged from the discharge ports 5a, 5b...
5i into conduits 11a, 11b...11i, and distributers 12a, 12b...12
Branch pipes 13a, 13a', 13b, 13 via i
b' . . . 13i, 13i' supplies the blast furnace B uniformly and without being unevenly distributed.

Further, the operation of the present invention will be explained in detail with reference to the above-mentioned embodiment.
Branch pipes 13a, 13a', 13b, 13b'...1 which are doubled by branching into two at each distributor using 12i
3i and 13i' to the tuyere of blast furnace B is the simplest method as shown in Figure 5, but due to some reason a problem occurs in the adjacent conduits 11a and 11b, and the supply of pulverized coal is interrupted. Assuming that has stopped,
When connecting the piping as shown in Fig. 5, the 4 tuyeres 14e, 14f, 14g, and 14h marked with an x in the figure are connected.
The fan-shaped zone at about 80 degrees to the core becomes non-flammable and cannot be heated, and since the non-flammable zone is unevenly distributed over a wide area, the width of the zone becomes large, and supplementation from the tuyeres adjacent to both ends is also limited to the center of the zone. This area that affects the temperature becomes a local cooling area within the furnace. However, in the case of the piping shown in Figures 1 and 4, the conduit 11
a, 11b are closed and the tuyeres 14a, 14a', 14b, 14b' are connected to the two branch pipes 13a, 13a', 13b, 13b' marked with △ in the figure, that is, approximately Nonflammable in a 40° fan-shaped zone.

However, since blast furnace B has a large diameter and combustion takes place through tuyeres that are arranged approximately evenly on its periphery, if there is one or two non-flammable tuyeres, combustion can occur from the tuyeres on both sides. This is compensated to a certain extent, and the effect on the entire inside of the reactor is alleviated as much as possible, and since the two non-combustible zones are located far apart and symmetrically, it is possible to avoid the negative effects of local cooling. The piping configuration shown in FIGS. 1 and 4 is an essential condition of the present invention.

Furthermore, since the present invention is a volumetric metering type, even if the pressure inside the tank 2 or the pressure loss inside the conduits 11a, 11b, . Therefore, there are fewer restrictions on piping and layout design, and there is no need to lift the conduit 22 or source pipe 28 to near the top of the blast furnace B as in the prior art shown in FIG. can be kept to the necessary minimum.

(Effects) Since the present invention has the configuration and operation as described above, the degree of freedom in designing the arrangement of the conduit for pumping pulverized coal is very large. Therefore, compared to the conventional method, where the conduit was forced to be close to the high heat load areas unique to blast furnaces and areas where high-temperature gas leaks from the blast furnace, it is now possible to select piping locations that avoid areas with poor conditions. This improves the durability of the conduit and is extremely effective for maintenance.

Furthermore, even if an accident such as pipe blockage occurs, the branch pipes after the distributor are arranged in symmetrical positions of the blast furnace, so the tuyeres that are affected by the accident are also in symmetrical positions, and the tuyere is placed in a symmetrical position as in the blast furnace. In a vertical furnace where balanced combustion is important, the effect of suppressing the deterioration of the furnace condition is extremely large.

In addition, since the conventional device is a blow tank type, the amount of pulverized coal delivered from the tank is determined by measuring the amount of pulverized coal delivered within a certain time (t) (W) using a measuring device such as a load cell attached to the tank. It calculates in the form of dw/dt and corrects the difference from the standard value, and in order to correct this amount, the control method is to increase or decrease the pressure in the tank, so advanced instrumentation equipment is required. However, since the present invention is a volumetric metering type, the rotation speed of the metering feeder can be increased or decreased by controlling the variable speed motor without being affected by the pressure inside the tank. Just let it
Since the supply amount of pulverized coal can be controlled, sophisticated instrumentation equipment is not required, and equipment costs can be greatly reduced.

As described above, the present invention enables piping design with a high degree of freedom, significantly improving workability and ease of maintenance, as well as ensuring high distribution accuracy of the supplied pulverized coal, facilitating stable operation of the blast furnace. When an accident such as internal blockage occurs, the symmetrical arrangement of the conduits has a great effect in suppressing the deterioration of the furnace condition, and has a wide range of excellent industrial effects related to furnace operation.

[Brief explanation of drawings]

1 to 4 show the present invention, and the first
The figure is a schematic diagram showing an example of piping for a pulverized coal injection device,
Fig. 2 is a front view showing a partial cross section of the feeder, Fig. 3 is a bottom view of the feeder showing an example of the discharge port,
FIG. 4 is a plan view showing a normal connection method and operation of a branch pipe to the blast furnace tuyere; FIG. 5 is a plan view showing an example of a defective connection method and operation of a branch pipe to the blast furnace tuyere; Fig. 6 is a schematic diagram showing an example of a conventional pulverized coal injection device; Figs. 7, 8, and 9A are front views showing a partial cross section of an example of a conventional distributor; Fig. 9B is a plan view of Fig. 9A, Fig. 10 is a main piping diagram showing another example of the conventional blowing device, and Fig. 11 is a plan view of Fig. 9A.
The figure is an elevational view of FIG. A...Pulverized coal injection device of the present invention, B...Blast furnace,
M...Variable speed motor, 1...Pulverized coal receiving valve, 2
... Storage pressure vessel (tank), 3 ... Rotor,
4...Measuring square, 5...Discharge port, 6...Shielding plate,
7... Feeder, 8... Pressure gas source, 9... Gas introduction pipe, 10... Pressure equalization pipe, 11... Conduit, 12
...Distributor, 13... Branch pipe, 14... Tuyere.

Claims (1)

[Scope of Claims] 1. Pulverized coal in a storage pressure vessel is cut out by a volumetric feeder connected to the pressure vessel, and one end of a conduit connected to each of a plurality of discharge ports arranged in a row in the feeder. A pair of branch pipes branched from each distributor are connected to a plurality of tuyeres provided at the periphery of the blast furnace, which are located opposite to the center of the blast furnace. , a method for injecting pulverized coal, which is characterized by supplying it evenly into a blast furnace. 2 At the bottom of the pulverized coal storage pressure vessel, a volumetric feeder driven by a variable speed motor and discharging an equal amount of pulverized coal from multiple discharge ports is installed in series, and a conduit is connected to each of the discharge ports. A distributor is provided at the tip of each conduit to separate a pair of branch pipes, and each pair of branch pipes is connected to a plurality of tuyeres provided at the periphery of the blast furnace. A pulverized coal blowing device characterized by communicating with a mouth.