JPH04301020A - Structure for furnace lower part in fluidized bed reduction furnace - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to equipment for reducing iron ore using a fluidized bed reduction furnace.

0002

BACKGROUND OF THE INVENTION The smelting reduction method is attracting attention as an alternative to the conventional method of producing hot metal using a blast furnace. This method has been developed with the aim of producing hot metal at low cost by using fine ore, steam coal, and omitting the coking process. In addition, in order to effectively utilize the reducing power and heat of the exhaust gas generated in the smelting reduction furnace, a method has been developed in which the raw material ore is preheated and pre-reduced by supplying it to the fluidized bed reduction furnace as a fluidized gas.

[0003] As such a fluidized bed reduction device, Japanese Patent Application Laid-Open No. 1982
As disclosed in JP-A-269283 and JP-A-1-111807, there is a fine ore input part on the side, a carrier gas introduction part for forming a fluidized bed near the bottom, and a nozzle on the entire surface of the bottom plate of the fluidized bed. A circulating fluidized bed consisting of a fluidized bed (riser) equipped with a fluidizing gas introduction section and a powder circulation fluidization section (downcomer) for circulating powder via a cyclone outside of the fluidized bed (riser). There are two types: one with a cyclone and the other with a non-circulating fluidized bed in which the powdered reduced ore collected by the cyclone is not returned to the riser.

One of the problems with this fluidized bed reduction equipment is that the fine ore forming the fluidized bed may fall from the reducing gas injection nozzle, interfering with the stable operation of the equipment and reducing productivity. .

[0005] As a measure to prevent ore from falling from the nozzle, the blowing holes for the reducing gas are made small and a porous bed is used, in which the blowing holes are distributed over the entire surface, and in the case of a type that uses a blowing nozzle, the top of the nozzle is Some types have a cap attached to the top and have the air inlet oriented horizontally.

[0006]

[Problem to be solved by the invention] However, although such measures can be expected to have a considerable effect when the reducing gas used is a clean gas, as in the case of the above-mentioned smelting reduction method, the smelting reduction furnace When exhaust gas is injected as a reducing gas, this exhaust gas contains a large amount of impurities such as dust and metal oxide fumes generated during the melting reduction process, and these impurities adhere to the injection port and cause blockages. death,
Gas blowing becomes uneven, or ventilation becomes impossible, resulting in a situation where operations have to be temporarily stopped. If gas injection becomes uneven, reduced ore will fall downward from the nozzle in areas where particle flow is poor, making operations unstable.

The problem to be solved by the present invention is to prevent ore from falling from the fluidized bed even with a reducing gas containing a large amount of fumes, and to minimize the formation of deposits in the fluidized bed. The aim is to complete a fluidized bed furnace lower structure that allows stable operation.

[0008]

[Means for Solving the Problems] The present invention provides a furnace lower structure for blowing reducing gas into a fluidized bed, and provides a falling ore discharge mechanism at a position below a nozzle, and introduces reducing gas into a position above this falling ore discharge mechanism. It is characterized by connecting pipes.

[0009] As for the specific installation position of the falling ore discharge mechanism, it can be installed as a comprehensive device below the reducing gas header of the fluidized bed reducing device, or it can be installed as an individual device below each blow nozzle. A mechanism may also be provided.

[0010] Further, as the fallen ore discharge mechanism, a lock hopper can be provided in which a locking mechanism is provided on the hopper that temporarily stores the fallen ore.

[0011]

[Operation] Rather than preventing ore from falling into the nozzle, the present invention aims to circulate and reuse the ore by actively collecting the ore into the nozzle. As for the structure, it is possible to use a simple cylindrical structure with the highest blowing efficiency and a relatively large diameter. Thereby, the formation of deposits on the nozzle can be minimized and stable operation of the fluidized bed can be achieved.

[0012] Furthermore, even if the reduced ore above the nozzle falls out of the nozzle during an emergency shutdown of the furnace, by using the falling ore discharge mechanism, it can be easily and quickly discharged from the system, so that it can be restarted. It is possible to raise it.

By using a rock hopper as the falling ore discharge mechanism, when the amount of falling ore exceeds a certain amount, the upper gate valve is closed and the falling ore is stored in the hopper. N2 purge gas is introduced into the hopper,
Purge the inside of the hopper with N2 to prevent harmful reducing gas from entering the furnace. After that, the upper valve is closed and the lower valve is opened to discharge the fallen ore out of the system. This allows for smooth treatment of fallen ore. By purging the inside of the hopper with N2, the gas inside the device will not leak out of the device when discharging fallen ore.

[0014]

[Example] As an example of the present invention, an example in which the present invention is applied to a circulating type fluidized bed reduction apparatus will be shown below.

FIG. 1 shows a first embodiment of the present invention in which a fallen ore discharge mechanism is provided at a position below a reducing gas header.

In the figure, a circulating fluid reduction device 20 includes a riser 2 having an ore supply pipe 21 and a reduced ore discharge pipe 22.
3, and an external particle circulation device 26 consisting of a cyclone 24 and a downcomer 25, and the riser 23 and external particle circulation device 26 are connected to each other by a circulation introduction pipe 27 in the upper part and a connecting pipe 28 in the lower part. connected. Reference numeral 29 denotes an inert carrier gas introduction pipe to the riser 23. The carrier gas from the introduction pipe 29 is once introduced into the carrier gas header 30, and from there passes through the breathable nozzle support plate 31 into the riser 23. It is squirted. Reducing gas is introduced into the riser 23 from a melting reduction furnace (not shown) through a reducing gas introduction pipe 32, and is supplied to a reducing gas header 3 located below the floor bottom plate 33.
4, a large number of nozzles 3 are uniformly arranged on the 33 sides of the floor bottom plate.
5 into the riser 23.

Reference numeral 10 shows a fallen ore discharge device according to the present invention. This ore discharge device 10 has a hopper 3 which is connected via an inlet valve 2 to a discharge pipe 1 which is provided at the lowest position of a reducing gas header 34 whose bottom surface is shaped like an inverted cone. The hopper 3 is provided with a purge gas introduction pipe 4 for introducing purge N2 gas and an outlet valve 5 for discharging it.

[0018] In this device, the reducing gas is supplied to the header 3.
4, and is discharged from the nozzle 35 into the fluidized bed riser 23. The fine ore supplied into the fluidized bed from the ore supply pipe 21 is reduced by the reducing gas. During the discharge process of this reducing gas, relatively coarse particles in the fine ore fall from the nozzle 35 into the header 34 and accumulate there. When a certain amount or more of fallen ore accumulates in the header 34, the hopper inlet valve 2
is opened and the fallen ore is thrown into the hopper 3. N2 gas is supplied into the hopper 3 from a purge gas introduction pipe 4, thereby purging the gas inside the hopper 3. After the fallen ore is thrown in, the inlet valve 2 is closed, and then the outlet valve 5 is opened to discharge it out of the system and reuse it.

FIG. 2 shows another embodiment of the present invention in which the ore discharge mechanism is provided in the reducing gas injection nozzle itself.

[0020] In this example, the ore discharge device 10 includes:
Reducing gas introduction pipe 3 to the nozzle 35 formed relatively long
A sump 6 is provided in a discharge pipe 1 located below the sump 2, and a hopper 3 is provided below the sump 6 via an inlet valve 2. And this hopper 3 has N2 for purging.
A purge gas introduction pipe 4 for introducing gas and an outlet valve 5 for discharging gas are provided, and are operated in the same manner as in FIG. 1 above.

[0021]

[Effects of the Invention] The present invention provides the following effects.

(1) Since the treatment of fallen ore can be carried out smoothly, the operability of the fluidized bed apparatus is improved.

(2) The amount of gas in the fluidized bed flowing out of the system is small, and the safety of the entire apparatus is high.

(3) The function of the fluidized bed reducing apparatus does not stop due to clogging of the nozzle hole, and operability is improved.

[Brief explanation of drawings]

FIG. 1 shows a first embodiment of the present invention, and shows an example in which a falling ore discharge mechanism according to the present invention is provided at the bottom of a header.

FIG. 2 shows another embodiment of the present invention, in which an ore discharge mechanism according to the present invention is directly connected to each blowing nozzle.

[Explanation of symbols]

10 Discharge device 20
Circulating fluidized bed reduction device 21 Ore supply pipe 22
Reduced ore discharge port 23 riser
24 Cyclone 25 Downcomer
26 External particle circulation device 27 Circulation introduction pipe 28 Connecting pipe 29
Carrier gas introduction pipe 30 Carrier gas header

Claims (1)

[Claims] 1. In a furnace lower structure in which a plurality of reducing gas nozzles are arranged at the bottom of a fluidized bed reduction furnace, a gas header is provided below the reducing gas nozzles, and gate valves are provided at both ends at the lower end of the gas header. The lower structure of a fluidized bed reduction furnace is characterized by being equipped with a falling ore discharge mechanism consisting of a hopper.