JPH04301019A - Device for discharging reduced ore 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 apparatus, Japanese Patent Application Laid-Open No. 62-2
There is a type disclosed in Japanese Patent Publication No. 69283 and Japanese Patent Application Laid-Open No. 1-111807, and this type has a fine ore input part on the side, a carrier gas introduction part for forming a fluidized bed near the bottom, and a fluidized ore inlet part on the side. A fluidized bed (riser) equipped with a fluidizing gas introduction section with nozzles on the entire surface of the bottom plate of the bed, and a powder circulation fluidization section (downcomer) for circulating powder via a cyclone on the outside of the bed. There are two types: one has a circulating fluidized bed consisting of a cyclone, and the other has a non-circulating fluidized bed in which the powdered iron ore (reduced ore) collected by the cyclone is not returned to the riser.

[0004] In either type, the reduced ore discharge device is a rotary feeder or a screw feeder, which has a high gas pressure in the fluidized bed and has a high sealing property to prevent gas from leaking at the discharge section for harmful gases including CO, etc. Mechanical feeders and pneumatic feeders are used.

[0005]

[Problems to be Solved by the Invention] However, among the conventional reduced ore discharge devices for fluidized bed reduction furnaces, discharge devices using mechanical means such as rotary feeders and screw feeders do not have the internal temperature of the fluidized bed reduction furnace. 900~1000℃
Because the fine ore is cut at high temperatures and in a reducing gas atmosphere rich in corrosive gases such as H2O and SO2, the constituent materials deteriorate due to high-temperature corrosion and stress corrosion, and rotating parts due to mechanical wear. The problem is that many problems occur. Furthermore, the reducing gas contains several tens of percent of harmful gases such as CO and H2, and if it leaks out of the system, there is a great risk of explosion or poisoning resulting in serious human and material disasters. For this reason, a structure is adopted in which the gap between the blade edge of the rotary blade and the casing is reduced to prevent gas leakage. However, when cutting high-temperature powder ore, the seal on the cutting edge quickly wears out, causing gas leaks, and the gap between the cutting edges is small, causing powder particles to get caught and stop rotating. For this reason, operability was extremely poor and maintenance costs were high.

[0006] On the other hand, in the case of a gas conveyance type discharge device using a carrier gas such as a pneumatic feeder, there is no rotating member for cutting out, so the above-mentioned problems are not present and the device is superior. I can say that.

However, in the case of this pneumatic feeder, if the pressure difference between the pressure inside the fluidized bed and the outside pressure is large, the pressure inside the fluidized bed will be affected by the pressure fluctuations, and the pressure inside the fluidized bed will decrease. When the iron ore rises, the iron ore in the powder seal part of the pneumatic feeder is discharged to the outside air at once, and the gas in the layer protrudes from the discharge port, making it impossible to control the cutting. Once the powder seal part of the pneumatic feeder breaks, the particles accumulate in that part because they are transported by gas, and the powder seal mechanism cannot be easily recovered, making stable operation impossible. There is.

[0008] The problem to be solved by the present invention is to solve the drawbacks of a reduced ore discharge device using gas conveyance in a powdered iron ore reduction device using a fluidized bed, and to enable stable discharge of reduced ore. The purpose is to find out.

[0009]

[Means for Solving the Problems] The present invention is a gas conveyance type reduced ore discharge device equipped with a working gas injection nozzle for a fluidized bed reduction furnace. It is characterized by providing a pressurizing means for adjusting the pressure difference between the pressure inside the furnace and the pressure inside the furnace.

As this pressurizing means, a retention tank such as a hopper is connected to the downstream side of the gas conveyance type discharge device, and a pressurization device for introducing an inert gas such as N2 gas is provided to the retention tank. This pressurizing device is provided with a differential pressure regulating valve that connects the pressure detector in the fluidized bed and the pressure detector in the retention tank, detects the pressure difference therebetween, and adjusts the differential pressure to a constant value.

[0011] In addition, a flow rate adjustment device is provided to control the amount of reduced ore discharged by installing a measuring device such as a load cell in the retention tank and to control the amount of carrier gas consisting of an inert gas blown into the gas conveyance type discharge device. By providing this, the amount of reduced ore discharged can be controlled.

0012

[Operation] By adjusting the pressure on the discharge side of the gas conveying type discharge device and the pressure in the fluidized bed to a constant pressure difference that prevents the gas from protruding inside the furnace in the gas conveying type discharge device, the pressure inside the fluidized bed is The reduced ore can be discharged stably without being affected by pressure fluctuations. Further, the gas in the fluidized bed does not protrude from the outlet due to an increase in the pressure in the fluidized bed.

In this case, the discharge of the reduced ore becomes more stable if the pressure on the discharge side of the gas conveyance type discharge device is adjusted to be higher than the pressure in the fluidized bed.

Furthermore, since a metering device is provided in the retention tank and the amount of reduced ore discharged is adjusted by controlling the carrier gas amount of the gas conveying type discharge device, a predetermined production amount can be stably obtained.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example in which a discharge device 10 of the present invention is applied to a circulating fluidized bed reduction device 20.

In the figure, a circulating fluidized bed reducing device 20 is composed of a riser 23 having an ore inlet pipe 21 and a reduced ore discharge pipe 22, and an external particle circulation device 26 comprising a cyclone 24 and a downcomer 25. , the riser 23 and the external particle circulation device 26 are connected at the upper part by a circulation introduction pipe 27 and at the lower part by a connecting pipe 28. 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 gas header 30, and from there passes through the breathable nozzle support plate 31 into the riser 23. It is squirted. Reducing gas introduction pipe 3 from a melting reduction furnace (not shown)
The reducing gas introduced into the riser 23 by 2 passes through a reducing gas header 34 located below the floor bottom plate 33, and is introduced into the riser 23 from nozzles 35 uniformly arranged on the floor bottom plate 33.

In the figure, a reduced ore discharge device 10 according to the present invention is connected to a hopper 4 having a discharge valve 3 via a telescoping pipe 2 further downstream of a pneumatic feeder 1 connected to a reduced ore discharge pipe 22. ing. 5 indicates a load cell installed in the hopper 4 for measuring the weight of the reduced ore. In addition, hopper 4 is equipped with N2 for pressurization.
A gas introduction pipe 6 is attached. Further, the pneumatic feeder 1 is also provided with an N2 gas introduction pipe 7 as a carrier gas. Furthermore, 8 is fluidized bed riser 2
3 shows a furnace pressure detector for detecting the pressure within 3.

The discharge device 10 according to the present invention having such a configuration operates in the following manner. Fine ore is introduced into the circulating fluidized bed reduction device 20 through an ore introduction pipe 21 using a rotary feeder or the like. The reducing gas is blown into the fluidized bed from the nozzle 35 to partially reduce the ore, and the exhaust gas is discharged from the circulation introduction pipe 27 to the outside via the cyclone device 24. Further, the reduced ore is discharged from the reduced ore discharge pipe 22, the discharge amount thereof is controlled by the pneumatic feeder 1, and the reduced ore is temporarily stored in the hopper 4. The internal pressure of the hopper 4 is adjusted by a pressure regulating valve 9 that receives a signal from a furnace pressure detector 8. The amount of reduced ore discharged from the pneumatic feeder 1 is controlled by adjusting the flow rate adjustment valve 11 of the N2 carrier gas supplied into the pneumatic feeder 1 through the gas introduction pipe 7. Hopper 4
A load cell 5 attached to the hopper measures the amount of reduced ore to be discharged, and when the amount of ore stored in the hopper 4 exceeds a certain level, the discharge valve 3 provided below is operated to discharge the ore.

[0019]

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

(1) Since there is no rotating member in the discharge device itself, there is no occurrence of troubles such as wear and corrosion in the discharge device itself.

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

(3) Since discharge control becomes possible more accurately, stable operation of the entire apparatus becomes possible.

[Brief explanation of drawings]

FIG. 1 shows a diagram in which a discharge device according to the present invention is applied to a circulating fluidized bed reduction device.

[Explanation of symbols]

10 Discharge device 20
Circulating fluidized bed reduction device 21 Ore introduction 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 Gas header 31 Nozzle support plate 32 Reducing gas introduction pipe 33 Floor bottom plate
34 Reducing gas header 35 Nozzle 1 Pneumatic feeder 2 Telescopic tube 3
discharge valve
4 Hopper 5 Load cell
6,7 N2 gas introduction pipe 8 Furnace pressure detector 9
Pressure control valve 11 Flow rate control valve

Claims (1)

[Claims] Claim 1: A gas conveyance type reduced ore discharge device equipped with a working gas injection nozzle for a fluidized bed furnace, wherein the gas conveyance type reduced ore discharge device is provided with a differential pressure between the pressure inside the fluidized bed reduction furnace and the pressure inside the furnace. A reduced ore discharge device for a fluidized bed reduction furnace equipped with a pressurizing means for adjustment.