JPH04191309A - Pre-reduction furnace in smelting reduction device for iron ore - Google Patents

Abstract

PURPOSE:To efficiently prevent the sticking and the growth of dust to a dispersing plate by injecting high pressure gas toward the lower face of the dispersing plate from plural gas supplying holes opened at plural recessed parts in a blasting device disposed at a bottom part in a pre-reduction furnace. CONSTITUTION:In a fluidized bed type pre-reduction furnace segmented with a pre- reduction chamber 12 and a gas injecting chamber 13 with the dispersing plate 5 penetrating plural nozzle holes 6, the blasting device is disposed at the bottom part of the furnace. The blasting device is constituted by disposing plural recessed parts 8 at the upper face of the bottom plate 7 in the furnace and opening the gas supplying holes 9 disposed at the inside of the bottom plate 7 at the bottom part of the above- mentioned each recessed part 8 so as to supply the gas into the gas supplying hole 9 from the outside of the furnace through the gas supplying pipe 10. During operating the furnace, the high pressure gas introduced from the above-mentioned gas supplying pipe 10 is periodically supplied into the gas supplying hole 9 and injected toward the lower face of dispersing plate 5 together with particles stored in the recessed part 8. By this method, the dust stuck to the lower face of dispersing plate 5 and the vicinity of the inlet of the nozzle hole 6 is removed.

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,
High level of technical perfection.

Moreover, a bubbling fluidized bed is particularly advantageous in that it 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 hole of one dispersion plate into the upper pre-reduction chamber, 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 in many cases, fine dust of 10 μm or less cannot be removed by a dust removal device such as a cyclone. 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 (particularly the inner surface on the entry side of the nozzle hole). These dust particles 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, 2 is a dispersion plate, and 3 is a fluidized bed.
4 is the gas blowing chamber below the dispersion plate, and 4 is the deposited and grown dust.

The present invention was 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.

[Means for Solving the Problems] For this reason, the present invention provides a fluidized bed reduction furnace having a dispersion plate in which a large number of nozzle holes are penetrated. A blasting device is provided, which comprises a plurality of recesses provided in the bottom plate, gas supply holes provided in the bottom plate so as to open at the bottoms of the respective recesses, and a supply means for supplying gas from outside the furnace to the gas supply holes. Its characteristic is that

[Effect]

Particles such as shot are charged into the recess on the top of the bottom plate,
During operation of the furnace, high-pressure gas is periodically supplied from the supply means to the gas supply hole to inject the particles in the recesses toward the lower surface of the dispersion plate. As shown in FIG. 2, by spraying the particles, dust adhering to the lower surface of the dispersion plate and near the entrance of the nozzle hole is removed.

The removed dust aggregates fall and accumulate in the recesses, where they are used as particles for primary blasting. This dust agglomerate has a certain degree of hardness and can be used sufficiently as particles for blasting. Therefore, basically, the apparatus of the present invention does not require replenishment of blasting particles from outside the furnace.

Normally, the gas flow velocity in the gas blowing chamber below the distribution plate is several m/s.
ee, and therefore the injection speed of the particles is several tens of meters.
It is preferable to supply high pressure gas for 1 sec or more.

〔Example〕

FIG. 1 shows an embodiment of the present invention, in which 5 is a dispersion plate;
Reference numeral 6 indicates a large number of nozzle holes provided in this distribution plate, and 7 indicates a bottom plate of the furnace. The dispersion plate 5 partitions the interior of the pre-reduction furnace into upper and lower parts, with the upper part forming the pre-reduction chamber 12 and the lower part forming the gas blowing chamber 13.
3 is provided with a gas inlet (not shown), to which a gas conduit from the melting reduction furnace is connected.

A large number of recesses 8 are provided on the upper surface of the bottom plate of the furnace. In this embodiment, these recesses 8 have a cone-shaped cross section. The recesses 8 are preferably provided as densely as possible on the upper surface of the bottom plate in order to collect the removed dust aggregates therein as particles for blasting.

Gas supply holes 9 are provided inside the bottom plate 7 so that their upper ends open at the bottoms of each of the four sections 8 . and,
At the lower ends of these gas supply holes 9.

A gas supply pipe 10 that supplies gas from outside the furnace is connected. Note that 11 is a valve provided in the gas supply pipe 10.

According to the above configuration, particles such as shot are first charged into the recess 8 on the upper surface of the bottom plate. During operation of the furnace, a high pressure gas such as N2 is periodically supplied from the gas supply pipe 10 to the gas supply hole 9 to inject the particles A in the recess 8 toward the lower surface of the dispersion plate 5.

By spraying the particles A, dust adhering to the lower surface of the dispersion plate 5 and near the entrance of the nozzle hole 6 is removed.

The removed dust aggregates fall and accumulate in the recess 8,
Used as particles for the next blast.

The high-pressure gas from the gas supply pipe 10 is normally supplied at a pressure of 1 to 2 m/sec or more so that the particle injection speed is several tens of m/sec or more.
Supplied for seconds.

〔Effect of the invention〕

According to the present invention described above, since the adhesion and growth of dust on the lower surface of the dispersion plate and near the entrance of the nozzle hole is effectively prevented, it is possible to stably blow exhaust gas into the fluidized bed. can.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention. Second
The figure is an explanatory diagram showing the state of dust adhesion in a conventional preliminary reduction furnace. In the figure, 5 is a dispersion plate, 6 is a nozzle hole, 7 is a bottom plate, and 8
9 is a recessed portion, 9 is a gas supply hole, and 10 is a gas supply pipe.

Claims (1)

[Claims] In a fluidized bed pre-reduction furnace which has a dispersion plate with a large number of nozzle holes penetrated inside the furnace, the bottom of the furnace has a plurality of recesses provided on the upper surface of the bottom plate of the furnace, and the bottom of each of the recesses inside the bottom plate. A preliminary reduction furnace in iron ore smelting and reduction equipment, characterized in that it is equipped with a blasting device consisting of a gas supply hole provided so as to open into the gas supply hole, and a supply means for supplying gas from outside the furnace to the gas supply hole. .