JPH04116113A - Prereducing furnace for iron ore smelting reduction equipment - Google Patents

Abstract

PURPOSE:To prevent the deposition and growth of dust on the inner surface of a nozzle hole by providing a spiral groove on the inner surface of a diffuser plate partitioning the inside of the furnace and moving a ball along the groove. CONSTITUTION:A nozzle hole 6 consisting of a metallic tube 8 is provided to a diffuser plate 5 vertically partitioning the inside of a prereducing furnace. A spiral groove 9 having a semicircular cross section is furnished on the inner surface of the hole 6 from the lower to upper ends. When dust deposits on the inner surface of the hole 6, a solid ball 12 is force-fed to the inside of the inlet of the hole 6 by a gas through a ball feed passage 10. The ball 12 is spirally moved toward the outlet along the groove 9. Consequently, the deposit on the inner surface of the hole 6 is scraped off by the moving ball and finally discharged into a prereducing chamber 13 above the diffuser plate 5. The waste gas is stably blown into the fluidized bed in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] This invention relates to an improvement of a preliminary reduction furnace in an iron ore smelting reduction facility.

[Conventional technology]

For smelting reduction of iron ore, an economical method is to configure the equipment with a smelting reduction furnace and a fluidized bed pre-reduction furnace, and use the exhaust gas generated in the smelting reduction furnace to fluidize the fluidized bed of the pre-reduction furnace and as reducing gas. It is preferable. And as this fluidized bed,
A bubbling fluidized bed is particularly advantageous because it has a high degree of technical perfection and can suppress powdering caused by preheating and reduction of ore.

This pre-reduction furnace is equipped with a dispersion plate having a large number of nozzle holes (gas holes) for ejecting gas therein, and iron ore is charged into a pre-reduction chamber formed above the dispersion plate. The exhaust gas (reducing gas) from the melting reduction furnace is introduced into the gas blowing chamber (wind box) below the distribution plate. This reducing gas is blown out through the nozzle holes of the dispersion plate into the preliminary reduction chamber above, thereby forming a fluidized bed and pre-reducing and preheating the iron ore.

[Problem to be solved by the invention]

In such a preliminary reduction furnace, adhesion of dust contained in the exhaust gas to the dispersion plate poses a major problem.

In other words, the exhaust gas generated from the smelting reduction furnace contains a large amount of dust, and of this, fine dust of less than 10 microns cannot be removed by dust removal equipment such as cyclones in many cases. The exhaust gas is directly introduced into the preliminary reduction furnace.

Since the above dust contains a large amount of alkaline compounds such as S, Na, and K, it becomes sticky in the exhaust gas at a temperature exceeding 900°C. Therefore, the dust introduced into the pre-reduction furnace will stick to the bottom surface of the dispersion plate and the like. It will adhere to the inner surface of the nozzle hole. In particular, the exhaust gas introduced into the gas blowing chamber is contracted when passing through the nozzle hole, and the gas flow rate inside the nozzle hole is extremely high (flow rate of more than 200 m/see), so dust is generated on the inner surface of the nozzle hole. Particularly easy to adhere firmly. Such dust deposits gradually grow and eventually impede the smooth flow of the reducing gas, making it impossible to form a proper fluidized bed.

Figure 2 shows this situation, where 1 is a fluidized bed and 2 is a fluidized bed.
3 is a dispersion plate, 3 is a gas blowing chamber below the dispersion plate, and 4 is attached and grown dust.

The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a pre-reduction furnace that can effectively prevent dust from adhering to and growing on a dispersion plate, particularly on the inner surface of a nozzle hole.

[Means to solve the problem]

For this reason, the present invention provides a fluidized bed pre-reduction furnace that has a dispersion plate with a large number of nozzle holes inserted therein, in which a spiral groove is formed on the inner surface of each nozzle hole of the dispersion plate from the inlet to the outlet of the nozzle hole. The present invention is characterized in that a spherical supply channel is provided inside the dispersion plate, the end of which opens into a spiral groove near the nozzle hole entrance.

[Effect]

A solid sphere is supplied to the inside of the nozzle hole on the inlet side through the supply path. The gas flow velocity inside the nozzle hole is several tens of meters or more, and the sphere pushed into the nozzle hole moves toward the exit of the nozzle hole while rotating along the spiral groove due to the force of the gas flow. Scrape off the dust attached to the inner surface. Finally, the spheres are discharged from the nozzle hole exit into the fluidized bed above the distribution plate.

〔Example〕

FIG. 1 shows an embodiment of the present invention, and shows one nozzle hole 6 provided in a dispersion plate 5 in a preliminary reduction furnace. The distribution plate 5 partitions the inside of the preliminary reduction furnace into upper and lower parts.
The upper part constitutes a preliminary reduction chamber 13, and the lower part constitutes a gas blowing chamber 14, respectively. This gas blowing chamber 14 is provided with a gas blowing port (not shown), to which a gas conduit from the melting reduction furnace is connected.

The nozzle hole 6 is constituted by a metal tube 8 embedded in a dispersion plate main body 7 made of refractory material.

A spiral groove 9 is provided on the inner surface of the nozzle hole constituted by the metal cylinder B from the nozzle hole outlet (lower end) to the outlet (upper end). This spiral groove 9 has a semicircular cross section, and the grooves are closely spaced so that the sphere moving along the spiral groove can come into contact with a wide range of the inner surface of the nozzle hole.

On the other hand, a spherical supply channel 10 is provided inside the dispersion plate 5 near the gas blowing chamber 14, and the end thereof opens 11 into the spiral groove 9 near the nozzle hole entrance.

The other end of this sphere supply path 10 communicates with the outside of the furnace through the furnace body of the preliminary reduction furnace.

In the preliminary reduction furnace, when high temperature exhaust gas containing a large amount of dust passes through the dispersion plate 5 for a long time, deposits of dust are generated on the inner surface of the nozzle hole 6. In the pre-reduction furnace of the present invention, the solid spheres 1 are
2 is supplied to the inside of the nozzle hole 6 on the entrance side through the sphere supply path 1o. The supply of the spheres is performed by pressure feeding using N2 gas or the like. The gas flow velocity inside the nozzle hole is several + m/sec.
e or more, the sphere 12 pushed out inside the nozzle hole is
It moves toward the exit of the nozzle hole while turning along the spiral groove 9 due to the force of the gas flow, and during this movement, the deposits adhering to the inner surface of the nozzle hole are scraped off. Finally, the sphere 12 is moved from the nozzle hole exit to the preliminary reduction chamber 13 (fluidized bed) above the dispersion plate.
is discharged. Therefore, as the sphere 12, it is preferable to use one having the same composition as iron ore (Fe, O, Fed) or a steel ball.

By periodically supplying the spheres 12 as described above, it is possible to prevent the formation and growth of deposits on the inner surface of the nozzle hole.

〔Effect of the invention〕

According to the present invention as described above, since adhesion and growth of dust on the inner surface of the nozzle hole of the dispersion plate is effectively prevented, exhaust gas can be stably blown into the fluidized bed.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a dispersion plate in one embodiment of the present invention. FIG. 2 is an explanatory diagram showing the state of dust adhesion in a conventional pre-reduction furnace. In the figure, 5 is a dispersion plate, 6 is a nozzle hole, 9 is a spiral groove,
10 is a sphere supply path, 11 is an opening, and 12 is a sphere. No.

Claims (1)

[Claims] In a fluidized bed pre-reduction furnace that has a dispersion plate with a large number of nozzle holes penetrated inside the furnace, a spiral groove is provided on the inner surface of each nozzle hole of the dispersion plate from the nozzle hole inlet to the outlet. A preliminary reduction furnace for iron ore smelting and reduction equipment, characterized in that a spherical supply path is provided whose end opens into a spiral groove near the nozzle hole entrance.