JPH0723491B2 - Circulating fluidized bed preliminary reduction device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fluidized bed preliminary reduction furnace for iron ore used in a smelting reduction method.

[Prior Art] In order to reduce iron ore to produce hot metal, a method of using a blast furnace, a method of melting iron ore reduced in a shaft furnace in an electric furnace, and the like have been conventionally adopted.

In the method using a blast furnace, a large amount of coke is used as a heat source and a reducing agent, iron ore as an iron source is usually sintered to improve air permeability and reducing property in the furnace,
It is charged into a blast furnace as a sinter.

Therefore, in the blast furnace method, not to mention a great equipment cost,
It requires a lot of energy and labor.

On the other hand, the iron ore reduction method using the shaft furnace has a drawback in that it requires pretreatment for pelletizing the iron ore and consumes a large amount of reducing agent, expensive natural gas as a heat source, and the like.

The smelting reduction method has been attracting attention as an alternative to such conventional hot metal production technology. The smelting reduction furnace used in this method was developed for the purpose of producing a molten iron-based alloy by a smaller-scale facility without being restricted by the raw material used.

The present inventors previously proposed one of such smelting reduction methods in Japanese Patent Laid-Open No. 61-64807.

Furthermore, the present inventors have proposed in Japanese Patent Application No. 61-286599 the pre-reduction device shown in FIG.

That is, an external particle circulation device is attached to the fluidized bed reduction furnace. The structure of this external particle circulation device is such that a cyclone 31 is connected to the outlet provided at the upper part of the fluidized bed reduction furnace 6 to reduce the reducing gas.
It captures fine particles that have been scattered along with 11.

A hopper 32 for temporarily storing the captured particles is connected to the lower part of the cyclone 31, and the hopper 32 temporarily stores the particles, and a predetermined amount is returned to the fluidized bed reduction furnace 6 by the circulation cutting device 33.

On the other hand, in the furnace of the fluidized bed reduction furnace 6, a plurality of gas outlets 34,
35 are formed. A bubbling fluidized bed 36 is formed in the middle of the gas outlets 34, 35.
A circulation outlet of the external particle circulation device is provided in the inside of 36.

Further, a packed bed 37 is formed at the bottom of the fluidized bed reduction furnace 6, and a furnace bottom blowing nozzle 38 is provided in the packed bed 37.

In the figure, 39 is a cutoff valve for charging the raw material 25 such as powdered ore and limestone into the fluidized bed reduction furnace 6, 40, 41 and 42 are flow rate control valves for adjusting the blowing amount of reducing gas, and 43 is A fine-grained reduction ore valve, 44 is a coarse-grained reduction ore valve.

(Problems to be Solved by the Invention) The present invention provides a device for easily controlling the circulation amount in a fluidized bed preliminary reduction device for fine iron powder.

(Means for Solving the Problems) The present invention is a facility for producing reduced ores, in which a fluidized bed reduction furnace is provided with an external particle circulation device, and the external particle circulation device is provided with a sedimentation tower, and the sedimentation tower is horizontally provided at the bottom thereof. And a control gas provided with a wrap length 1 with the horizontal region in the horizontal region of the settling tower while the reducing gas injection nozzle is erected on the bottom of the reduction furnace. This is a circulating fluidized bed preliminary reduction device in which a blowing nozzle or a blowing nozzle group is slidably provided horizontally.

The present invention will be described below with reference to the drawings.

FIG. 1 is an overall view of the present invention, and FIG. 2 is an explanatory view of essential parts of the present invention. In the figure, 6 is a fluidized bed reduction furnace, and 10 is a sedimentation tower, which constitutes an external particle circulation device. The upper part of the settling tower 6 communicates with the cyclone 31 and is provided with a selection system for gas and reduced iron powder.

The lower part of the sedimentation tower 10 forms a horizontal region 13 and is integrated with the lower part of the fluidized bed reduction furnace 6.

A reducing gas injection nozzle 38 is erected on the bottom of the reduction furnace 6,
Further, a control gas injection nozzle 12 is horizontally installed below the sedimentation tower 10.

The control gas injection nozzle 12 is connected to the settling tower 10 as shown in FIG.
It is provided with a horizontal area 13 and a lap length l, and is slidable in the settling tower 10 by a horizontal drive device 16. 15 is a hose and 44 is a reduced iron powder discharge port.

Therefore, according to the present invention, in the fluidized bed reduction furnace 6, a reducing gas is injected from the reducing gas injection nozzle 38 to form a fluidized bed, and the packed bed 45 is formed in the sedimentation tower by receiving the reducing action.

Further, a packed layer of reduced iron powder is formed in the horizontal region of the settling tower, but the control gas is blown into the horizontal region from the control gas blowing nozzle to give a circulating flow.

Although only one control gas injection nozzle is shown in FIGS. 1 and 2, the same applies to the case where a plurality of control gas injection nozzles are provided.

According to experiments, the circulating flow can be arbitrarily controlled by varying the wrap length 1 with the nozzle length in the horizontal region.

(Effects of the Invention) The present invention provides a horizontal part in the lower part of the circulating fluidized bed (between the sedimentation tower and the reduction reaction tower), and restricts the flow of the contents from the sedimentation tower to the reduction reaction tower at the horizontal part. A nozzle that ejects in the horizontal direction is provided in the horizontal portion to give a circulating force. Since this ejection nozzle can change the insertion length (l) into the horizontal portion, the circulation amount can be controlled by the ejection nozzle position and the ejection gas amount. Easy to do.

[Brief description of drawings]

FIG. 1 is an overall explanatory view of the present invention, FIG. 2 is an explanatory view of main parts of FIG. 1, and FIG. 3 is an explanatory view of a conventional example. 6: Fluidized bed reduction furnace, 10: Settling tower, 13: Horizontal area, 12: Control gas injection nozzle.

Claims (1)

[Claims] 1. A facility for producing reduced ore, wherein a fluidized bed reduction furnace is provided with an external particle circulation device, a sedimentation tower is provided in the external particle circulation device, and a horizontal region is provided below the sedimentation tower to effect fluidized bed reduction. The reducing gas injection nozzle is connected to the furnace and the reducing gas injection nozzle is erected on the bottom of the reduction furnace, and the control gas injection nozzle provided with the lap length l with the horizontal area is slidable in the horizontal area of the sedimentation tower. Circulating fluidized bed preliminary reduction device installed horizontally.