JPH05331516A - Particle circulating device for circulating type fluidized bed pre-reduction furnace - Google Patents

Abstract

PURPOSE:To efficiently, stably and circulatively fluidize powdery ore without any fear of the development of back flow gas in a circulating type fluidized bed pre-reduction furnace operation. CONSTITUTION:In a grain circulating device 7 composed of a vertical type circulating device body 8 and an inlet side sloped tube 9 and an outlet side sloped tube 10 incliningly arranged at the lower part and the upper part of the circulating device body, the cross sectional shape of this device body 7 is made to be rectangle and ratio Ri (A/B) of the long side A and the short side B in the rectangular cross section is adjusted in the range of 1.2-5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a particle circulation device for a circulating fluidized bed pre-reduction furnace used for preliminary reduction of powdery ores, and more particularly to efficient and stable particle circulation in a circulating fluidized bed. , It aims to stabilize the operation of the circulating fluidized bed preliminary reduction furnace and to improve the productivity.

[0002]

2. Description of the Related Art As a method for preliminarily reducing powdery ores using a circulating fluidized bed, when high temperature exhaust gas generated in a vertical smelting reduction furnace is introduced into a fluidized bed preliminary reduction furnace (riser), the gas in the fluidized bed is used. While introducing the flow velocity at a speed higher than the particle ejection velocity (particle termination velocity), the pre-reduced ore powder ejected from the fluidized bed pre-reduction furnace is collected by a cyclone, and the collected pre-reduced ore powder is A method is known in which particles are continuously returned from a particle reservoir (downcomer) to a fluidized bed preliminary reduction furnace in a closed circuit through a particle circulation device, and preliminary reduction is performed while such circulating flow is performed (for example, Japanese Patent Laid-Open Publication No. Hei 10 (1999) -264242). 1-306515, Japanese Patent Laid-Open No. 2-4909). In each of the circulating fluidized bed preliminary reduction furnaces, a particle circulation device is installed as a circulation amount control valve. This device is equipped with inlet and outlet ports at the bottom and top of the body with a cylindrical cross section, and a gas inlet for adjusting the amount of circulation at the bottom, so that the amount of gas for adjusting the amount of circulation can be increased or decreased. It has a mechanism to control the circulation amount of powdery ore particles.

FIG. 1 schematically shows a typical example of the circulating fluidized bed preliminary reduction furnace described above. In the figure, numeral 1 is a fluidized bed preliminary reduction furnace, 2 is a reducing gas introduced into the furnace, 3 is a hopper for powdered ore, 4 is a feeder, 5a and 5b are supply tubes for powdered ore, and 6 is The particle reservoir 7 is a particle circulation device, and the particle circulation device 7 is composed of a circulation device main body 8, and an inlet side oblique pipe 9 and an outlet side oblique pipe 10 which are obliquely provided at the lower part and the upper part thereof, respectively. Further, 11 is a gas inlet provided at the bottom of the circulation device body 8, 12 is a gas dispersion plate, 13 is a flow control valve, 14 and 15 are cyclones, 16 is a transport pipe, 17 is a discharge device,
18 is a powder transport pipe.

Now, as shown in FIG. 1, powdered ore cut out from the hopper 3 is supplied into the fluidized bed preliminary reduction furnace 1 from the lower part of the reduction furnace 1 through the supply pipe 5a, and Emission from smelting reduction furnace (not shown) 8
High-temperature exhaust gas at 00 to 1100 ° C. is introduced as a fluidized reducing gas 2 from the bottom of the reduction furnace 1, and a fluidized bed is formed in the furnace. It should be noted that from the hopper 3 to the particle reservoir 6 via the supply pipe 5b, powdered ore is also charged from above. Most of the pre-reduced ore powder 19a that has been pre-reduced in the fluidized bed pre-reduction furnace 1 and jumped out of the furnace 1 is collected by the cyclone 14 in the first stage and charged into the particle reservoir 6, It descends from the particle reservoir 6 to the circulation device body 8 via the inlet side inclined pipe 9. In the circulator 8 main body, the pre-reduced ore powder 19b is supplied by the particle circulation amount control gas 20 blown from the bottom thereof.
Is continuously circulated in a closed circuit to the fluidized bed preliminary reduction furnace 1 through the outlet side oblique pipe 10, whereby the fluidized bed preliminary reduction is performed. The fine pre-reduced ore powder 19c which is not collected by the cyclone 14 in the first stage is collected by the cyclone 15 in the second stage, and is sequentially passed through the transport pipe 16 to collect particles 6
Then, it is supplied again to the fluidized bed preliminary reduction furnace 1 as the preliminary reduced ore powder 19b by the particle circulation device 7.

The amount of particles retained in the fluidized bed preliminary reduction furnace 1 can be appropriately controlled by adjusting the particle circulation amount control gas 20 based on a signal detected by the differential pressure transmitter 21. .. Then, the preliminary reduced ore powder 19 in the circulation type fluidized bed preliminary reduction furnace system is cut out from the lower part of the particle reservoir 6 by the discharge device 17, and is supplied to the smelting reduction furnace via the powder transport pipe 18.

[0006]

In the circulation type fluidized bed, the pre-reduced ore powder jumped out from the fluidized bed preliminary reduction furnace is collected by a cyclone and continuously closed in a fluidized bed preliminary in a closed circuit through a particle circulation device. Since the method of returning to the reduction furnace is adopted, it is important for stable operation that the amount of ore powder retained in the fluidized bed preliminary reduction furnace is maintained at a certain level and is not changed. In the case of continuously pre-reducing powdered ore in a circulating fluidized bed, the dust collection efficiency of the pre-reduced ore powder in the cyclone and the stable movement of the ore powder in the circulation route stabilize the operation and improve the productivity. Is important in terms of maintenance. Further, the particle circulation device is required to have a function capable of stably supplying the powdery ore from the particle circulation system to the fluidized bed preliminary reduction furnace. In addition, it is advantageous in terms of equipment cost that the size is compact and efficient particle circulation is possible.

However, in the case of enlarging the particle circulation device from the viewpoint of improving the operating efficiency, the conventional particle circulation device has a cylindrical cross section in both the main body and the inlet and outlet slant pipes, so that the center of the cylinder is The amount of particles in the vicinity of the part cannot always be discharged from the circulation device outlet side according to the size of the enlarged device, so it is necessary to enlarge the particle circulation device more than necessary, and The circulation efficiency was not good. Further, if the particle size of the powdery ore becomes coarse, coarse ores easily accumulate in the circulation device, which is disadvantageous for stable particle circulation. Furthermore, since the cylindrical body has a cylindrical inlet and outlet, the reducing gas of the fluidized bed preliminary reduction furnace and the circulation amount adjusting gas introduced from the lower part of the circulation device, Since it was easy to rise as a backflow gas from the particle reservoir to the cyclone, the dust collection efficiency of the cyclone decreased and the particle circulation became unstable, which also adversely affected the operation itself of the circulating fluidized bed preliminary reduction reactor. .

The present invention advantageously solves the above problems, and proposes a particle circulation device capable of efficiently circulating and circulating powdery ore efficiently and without fear of backflow gas generation. With the goal.

The present inventors have made various studies on the cross-sectional shape of the path, based on the idea that the main cause of the above problem is the path shape of the particle circulation device. As a result, it was found that the intended purpose can be advantageously achieved by making the cross-sectional shape of the circulation device main body, and further the inlet-side and outlet-side oblique pipes a rectangular cross-section with a predetermined aspect ratio. The present invention is based on the above findings.

[0010]

Means for Solving the Problems That is, the present invention relates to a particle circulation device of a circulating fluidized bed pre-reduction furnace for introducing a reducing gas and pre-reducing while circulating and flowing a granular ore,
It is composed of a vertical circulation device main body, and an inlet side oblique pipe and an outlet side oblique pipe obliquely provided on the lower part and the upper part thereof, respectively, and the circulation device main body has a rectangular cross-sectional shape, and the long side A of the rectangular cross section.
And a short side B have a ratio R ₁ (A / B) of 1.2 to 5 in the circulating fluidized bed preliminary reduction furnace (first invention).

The present invention is the same as the first invention,
The cross-sectional shape of the inlet-side oblique pipe and the outlet-side oblique pipe is rectangular, and at least the long side C of the rectangular cross-section of the inlet-side outlet and the outlet-side outlet of the oblique pipe is
A ratio R ₂ of the long side C of the rectangular cross section of the circulation device main body and the long side C and the short side D of the rectangular cross section of the inlet side oblique pipe and the outlet side oblique pipe.
(C / D) is a particle circulation device (second invention) of a circulating fluidized bed preliminary reduction furnace, which satisfies the range of 1.2 to 5.

[0012]

2 (a) and 2 (b) show a conventional particle circulation device in plan view and front view, respectively, while in FIGS. 3 (a) and 3 (b).
Figure 1 also shows a particle circulation device according to the invention in plan and in front, respectively. Now, according to the present invention, the ratio R ₁ (A / B) of the long side A and the short side B of the rectangular cross section of the circulation device body is
If it is 1.2-5, compared to the case of the conventional cylindrical cross section,
When the cross-sectional areas of both cross sections were the same, the circulation capacity per cross-sectional area was improved by 20-50%. Therefore, if the same circulation capacity is required, the particle circulation device can be made compact accordingly. Furthermore, for the inlet and outlet oblique tubes of the circulation device body, the ratio of the long side C and the short side D of the rectangular cross section is adjusted to R ₂ (C / D) within the range of 1.2 to 5, and The long side C of each inlet and outlet is the long side A of the device body.
If it is made equal to, the amount of reducing gas from the fluidized bed preliminary reduction furnace and the amount of backflow gas of the circulation amount adjusting gas of the circulation device to the cyclone will decrease, and the particles will smoothly fall to the particle circulation device and the particle circulation will be stable. It became clear that it could be done.

[0013]

EXAMPLE An operation test was conducted under the conditions shown in Table 1 using the apparatus shown in FIG. 3 as the particle circulation apparatus of the circulation type fluidized bed preliminary reduction furnace shown in FIG. 1 above. The obtained operation test results are also shown in Table 1. Table 2 shows the specifications of the circulating fluidized bed preliminary reducing furnace and the vertical smelting reducing furnace.

[0014]

[Table 1]

[0015]

[Table 2] 1) Circulating fluidized bed preliminary reduction furnace Furnace diameter: 0.7 m Height: 7.3 m 2) Vertical smelting reduction furnace Furnace diameter: 1.2 m Furnace volume: 7.7 m Upper and lower tuyeres: 3 each

As shown in Table 1, in the conforming examples 1 and 2 in which the cross-sectional shapes of the main body of the particle circulation device and the inlet and outlet slant pipes are proper rectangular cross sections, the fluctuation of the circulation amount is reduced, and the reduction ore is reduced. It was possible to stably circulate the powder, and as a result, it was possible to obtain a high preliminary reduction rate and productivity, whereas in the comparative example where the circulation device body and the oblique pipe were cylindrical, troubles increased. The fly reduction rate and productivity were low.

[0017]

As described above, according to the present invention, the circulating flow of the reduced ore powder can be performed efficiently and stably. Therefore, the application of this particle circulation device stabilizes the operation of the circulating fluidized bed preliminary reducing furnace and It is possible to improve productivity.

[Brief description of drawings]

FIG. 1 is a schematic view of a typical circulating fluidized bed preliminary reduction furnace.

FIG. 2 is a view showing a conventional particle circulation device.

FIG. 3 is a diagram showing a particle circulation device according to the present invention.

[Explanation of symbols]

 1 fluidized bed preliminary reduction furnace 2 reducing gas 3 powdered ore hopper 4 feeder 5a, 5b powdered ore supply pipe 6 particle reservoir 7 particle circulation device 8 circulation device body 8 9 inlet side oblique pipe 10 outlet side inclined pipe 11 gas Inlet port 12 Gas dispersion plate 13 Flow control valve 14, 15 Cyclone 16 Transport pipe 17 Discharge device 18 Powder transport pipe 19 Pre-reduced ore powder 20 Particle circulation amount control gas 21 Differential pressure transmitter

Claims (2)

[Claims] 1. A particle circulation device of a circulating fluidized bed pre-reduction furnace which introduces a reducing gas and circulates and fluidizes granular ore while preliminarily reducing the ore. The circulator has a rectangular cross-section, and the ratio R ₁ (A / B) of the long side A and the short side B of the rectangular cross section is made up of an inlet side sloping tube and an outlet side sloping tube. Is 1.2
A particle circulation device of a circulating fluidized bed preliminary reduction furnace, characterized in that the range of 5 to 5 is satisfied. 2. The circulation device according to claim 1, wherein the cross-sectional shape of the inlet side slant pipe and the outlet side slant pipe is rectangular, and at least the long side C of the rectangular cross section of the inlet side port and the outlet side port of the slant pipe. The length R is equal to the long side A of the rectangular cross section of the main body and the ratio R ₂ (C / D) of the long side C and the short side D of the rectangular cross section of the inlet side oblique pipe and the outlet side oblique pipe is 1.2 to.
A particle circulation device for a circulating fluidized bed preliminary reduction furnace, characterized in that the range of 5 is satisfied.