JPH0788524B2 - Operation method of metal smelting reduction furnace - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is to charge a small or granular coal from the upper part of a furnace and to form a packed bed of carbonaceous material particles produced by dry distillation of the coal in the lower part of the furnace. A fluidized bed consisting of fine carbonaceous material particles produced during dry distillation of the coal is formed in the inner upper part, and from at least the uppermost tuyeres of the plurality of tuyeres arranged vertically in the furnace wall at the lower part of the furnace. The present invention relates to a method for operating a metal smelting reduction furnace that blows powdered ore.

[0002]

2. Description of the Related Art Having a plurality of tuyere at least two stages above and below, blown with powdered ore from at least the upper stage tuyere with high temperature air or high temperature air enriched with oxygen, and charging coal from the furnace top. For the metal refining method using the metal smelting reduction furnace, the Japanese Patent Publication No. 59-18453 or the Japanese Patent Publication No. 59-286.
It is disclosed in Japanese Patent Publication No. 05.

In this way, in a vertical metal smelting reduction furnace in which coal is directly charged from the top of the furnace and also coal is dry-distilled in the furnace, powdery carbonaceous material is generated in the upper part of the furnace due to thermal cracking etc. during dry-distillation of coal. To do. In order to prevent such powdery carbonaceous material from entraining in the rising gas in the furnace and flying out of the system as dust from the furnace top, it is effective to reduce the furnace top gas flow velocity. . As an operation method for reducing the gas flow rate in the furnace, a method of lowering the furnace top gas temperature to reduce the gas volume can be considered.

[0004]

As described above, when the coal is charged directly into the metal smelting reduction furnace from the top of the furnace and used, the gas temperature at the top of the furnace is reduced for the purpose of reducing the scattering of carbonaceous material due to dust. However, when the furnace top gas temperature is low, coal does not dry up sufficiently in the furnace and gas with a large amount of hydrocarbon components is generated, and in the exhaust gas duct of coal pitch, tar, etc. There is a problem such as adhesion, deposition, tar in the generated gas, agglomeration in dust removal processing equipment, and clogging of dust removal equipment.

Pyrolysis of coal generally starts at about 300 ° C., begins to generate gas and tar, and ends at almost 900 ° C. to become high temperature dry distillation coke, which is a metal considered in the present invention. In the smelting reduction furnace, the staying time in the carbonaceous material fluidized bed formed in the upper part of the furnace is shorter than that in a general coke oven, so even if the generated gas temperature is 900 ° C, the above-mentioned trouble of the exhaust gas system is not always prevented. It is not possible.

The present invention has been made in view of such circumstances, and an object thereof is to provide a method for operating a metal smelting reduction furnace capable of reducing hydrocarbons in the furnace top gas. is there.

[0007]

Means for Solving the Problems The present invention for achieving the above-mentioned object is to charge small lump-like or powder-grained coal from the upper part of a vertical smelting reduction furnace in which the upper part of the furnace is widened and to the lower part of the furnace. The coal forms a packed bed of carbonaceous material particles produced by dry distillation, and a fluidized bed composed of fine carbonaceous material particles produced during dry distillation of the coal is formed in the upper part of the furnace, and the upper and lower furnace walls at the bottom of the furnace are also formed. In a method for operating a metal smelting reduction furnace in which powdered ore is blown from at least the uppermost tuyere among a plurality of tuyere arranged in the direction, in the furnace top gas generated in the furnace upper part of the metal smelting reduction furnace This is a method for operating a metal smelting reduction furnace, which comprises measuring the temperature and controlling the furnace operating conditions so that the measured temperature becomes 950 ° C or higher to reduce the hydrocarbon concentration in the furnace top gas.

[0008]

FIG. 1 shows a vertical type metal smelting reduction furnace 1 in which the upper part of the furnace is widened, together with a fluidized bed preliminary reduction furnace 5. Metal smelting reduction furnace 1
Into the inside, lumpy or powdery coal is charged through a coal supply device 9, and a packed bed of carbonaceous material particles produced by coal dry distillation is formed in the lower part of the furnace of the metal smelting reduction furnace 1. In addition, a fluidized bed composed of fine carbonaceous material particles formed by thermal cracking or the like during dry distillation of coal is formed.

The upper tuyeres 2 and the lower tuyeres 3 are arranged on the furnace wall at the lower part of the furnace, and the upper tuyeres 2 and the lower tuyeres 3 are arranged.
The air supplied from the blower blower 11 is supplied to the blower temperature raising device 12
High-temperature air (hereinafter referred to as hot air) heated to 800 to 1300 ° C. is supplied through the annular pipe 16 and the tuyere blast branch pipe 17. An oxygen supply pipe 21 is connected to the blower duct 20 on the downstream side of the blower blower 11 so that the enriched oxygen flow rate control valve 15 can be controlled to enrich oxygen in the hot air. . Thus tuyere 2 and tuyere 3 in the furnace 1
At the tip of the blast furnace, a raceway is generated by hot air in the same way as at the tip of the tuyere of the blast furnace, and a high temperature region of 2000 to 2500 ℃ is formed.

On the other hand, the granular ore is supplied to the preliminary reduction furnace 5 from the ore supply device 8, and the furnace top gas generated in the metal melting reduction furnace 1 is introduced from the exhaust gas duct 18 to the lower part of the preliminary reduction furnace 5. The powdery ore loaded in the furnace 5 is dried, heated and pre-reduced by a fluidized system. The pre-reduced ore thus pre-reduced is located in the fluidized bed area.
It is further discharged and temporarily stored in the ore blowing tank 7 through the guide pipe 22. The dust-containing exhaust gas discharged from the upper part of the preliminary reduction furnace 5 is collected by the hot cyclone 6, and the recovered powder dust is collected in the ore blowing tank 7. The powdery granular reduction ore stored in the ore blowing tank 7 is supplied from the ore supply pipe 10 to the upper stage tuyeres 2 while controlling the supply amount by the blowing amount control device 4, and the hot air is passed through the upper stage tuyeres 2. Together with this, it is blown into the metal smelting reduction furnace 1. If necessary, it is also possible to supply the preliminary reduced ore to the lower tuyeres 3.

The pre-reducing ore blown from the upper tuyeres 2 together with hot air or enriched oxygen is immediately heated and easily melted. Then, while being dripped in the lower portion of the metal smelting reduction furnace 1, it is reduced and melted to generate molten metal and molten slag, which are stored in the hearth part and tapped from the tap hole (not shown) to the outside of the furnace in a timely manner. The operation of the smelting reduction furnace 1 as described above is conventionally known, but the smelting reduction in which a fluidized bed made of fine carbonaceous material produced by thermal decomposition of coal is held in the upper part of the furnace targeted by the present invention. In the furnace 1, the coal charged into the furnace from the coal supply device 9 at the upper part of the furnace enters into this carbonaceous material fluidized bed, and the heat therein causes rapid dry distillation. At this time, the volatile components are gasified and escape from the coal, and the coal becomes char containing cracks. This char is deposited as a packed layer between the upper and lower tuyeres to form a reduction reaction region. Also, due to the occurrence of these cracks and collision with other carbonaceous materials in the fluidized bed,
Fine coal char is generated and becomes suspended particles in the fluidized bed.

Generally, in a coke oven or the like, the higher the dry distillation temperature, the lower the CH ₄ and tar in the generated gas, and the higher the hydrogen, but in the metal smelting reduction furnace that forms the carbonaceous material fluidized bed, the tar in the generated gas, Hydrocarbon components such as pitch complicate the exhaust gas treatment and are not preferred. Therefore, the conditions under which the hydrocarbon content in the generated gas can be reduced to a level that does not pose a problem were obtained by hot experiments. Figure 2 shows the temperature of the gas generated at the top of the furnace and the CH ₄ concentration in the generated gas. As the furnace top temperature increased, the CH ₄ concentration in the generated gas decreased,
Almost no CH ₄ is contained above ℃.

Therefore, in the present invention, the CH ₄ concentration in the generated gas can be made almost zero by controlling the furnace operating conditions so that the generated gas temperature becomes 950 ° C. or higher, that is, in the generated gas. It is possible to eliminate the hydrocarbons. As a result, the components such as tar and pitch in the generated gas are eliminated, and the exhaust gas treatment can be easily performed. The means for controlling the furnace top gas temperature can be performed by enriching the oxygen of the air supplied from the blower blower to the tuyere of the smelting reduction furnace. That is, the temperature of the furnace top gas can be increased as the amount of oxygen in the supply air is increased. In addition to this, as means for raising the furnace top gas temperature, there are raising the blast temperature, blowing oxygen into the furnace top gas, and the like.

[0014]

EXAMPLES Example 1 FIG. 3 shows a vertical metal smelting reduction furnace 1 having a widened upper furnace equipped with a preliminary reduction furnace 5 shown in FIG. 1 and operated for about 10 days under the following operating conditions. The changes in the generated gas temperature, the CH ₄ concentration in the generated gas, and the changes in the volatile components in the generated dust are shown.

Operating conditions Vertical smelting reduction furnace Diameter: 1.2 m Furnace volume: 7.7 m Upper and lower tuyeres: 3 each Operating conditions Air flow rate: 1650 Nm ³ / h Enriched oxygen amount: 100-200 Nm ³ / h Air flow Temperature: 900 ° C Coal supply: 900kg / h Powder ore supply: 800kg / h (including flux) The top gas temperature generated as a test condition was set in the exhaust gas duct 18 between the reduction furnace 1 and the preliminary reduction furnace 5. Measured by the generated gas temperature detector 13, input this temperature measurement signal to the enriched oxygen flow rate controller 14, and enrich the amount of oxygen enriched in the air supplied from the blower blower 11 according to a command from the controller 14. The oxygen flow rate control valve 15 was controlled to gradually increase the temperature of the top gas of the reduction furnace 1 from about 800 ° C. to 1100 ° C. in steps to observe the changes in the components of the generated gas and generated dust.

As shown in FIG. 3, the CH ₄ concentration drops sharply at the generated gas temperature of 950 ° C., and almost completely disappears at 950 ° C. or higher. At the same time, the disappearance of volatile components in the generated dust was also seen. This suggests that the charge coal was completely dry-distilled at temperatures above 950 ° C and above. Example 2 The same furnace as in Example 1 was used and operated under the following operating conditions.

Operating conditions Blast rate: 1650Nm ³ / h Enriched oxygen content: 140Nm ³ / h Blast temperature: 900 ° C Coal supply rate: 900kg / h Powder ore supply rate: 800kg / h (including flux) Generated gas temperature is The temperature is 900 ° C, the methane concentration in the generated gas is 1.5%, and the tar and pitch in the generated dust are
It was 1.0%. Therefore, when the enriched oxygen amount was changed to 160 Nm ³ / h so that the gas generation temperature became 950 ° C, the gas generation temperature became 955 ° C. At this time, the methane concentration in the generated gas is 0.1%, and the tar and pitch in the generated dust are
It fell to 0.1%. I operated for 7 days under these operating conditions,
No pollution of the generated gas dust removal water was observed.

[0018]

As described above, according to the present invention,
It is possible to reduce the amount of high boiling point hydrocarbon compounds such as tar and pitch generated from the charged coal in the operation of the carbonized material fluidized bed smelting reduction furnace, and to pollute and block the gas ducts generated by these substances, as well as in gas dedusting equipment. It becomes possible to prevent troubles and the like.

[Brief description of drawings]

FIG. 1 is a schematic view of an apparatus according to an embodiment of the present invention.

FIG. 2 is a graph showing the relationship between the generated gas temperature and the CH ₄ concentration in the generated gas.

FIG. 3 is a graph showing changes in generated gas temperature, generated gas methane concentration, and volatile components in generated dust.

[Explanation of symbols]

 1 Vertical smelting reduction furnace with widened furnace top 2 Upper stage tuyeres 3 Lower stage tuyeres 4 Blow-in amount control device 5 Preliminary reduction furnace 6 Hot cyclone 7 Ore blowing tank 8 Ore supply device 9 Coal supply device 10 Ore supply pipe 11 Blower blower 12 Blower temperature raising device 13 Evolved gas temperature detector 14 Enriched oxygen flow rate controller 15 Enriched oxygen flow rate control valve 16 Annular pipe 17 Tuyere blast branch pipe 18 Exhaust gas duct 19 Exhaust device 20 Air duct 21 Oxygen supply pipe 22 Induction pipe

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiko Sato 1 Kawasaki-cho, Chiba-shi, Chiba Kawasaki Steel Co., Ltd. Technical Research Division (72) Inventor Taro Kusakabe 1 Kawasaki-cho, Chiba-shi Kawasaki Steel Co., Ltd. Within Research Headquarters (56) Reference JP-A-5-9527 (JP, A)

Claims (1)

[Claims] 1. A small lump-like or powdery coal is charged from the upper part of a vertical smelting reduction furnace having an expanded upper part and a packed bed of carbonaceous material particles produced by dry distillation of the coal is formed in the lower part of the furnace. Along with the formation, a fluidized bed composed of fine carbonaceous material particles produced during dry distillation of the coal is formed in the upper part of the furnace, and at least the most of the tuyeres arranged in the vertical direction of the furnace wall in the lower part of the furnace. In the operating method of the metal smelting reduction furnace in which powdered ore is blown from the tuyere of the upper stage, the temperature of the top gas generated in the upper part of the metal smelting reduction furnace is measured, and the measured temperature should be 950 ° C or higher. A method for operating a metal smelting reduction furnace, characterized in that the furnace operating conditions are controlled to reduce the hydrocarbon concentration in the top gas.