KR100972195B1 - Method for manufacturing molten irons by injecting a hydrocarbon gas and apparatus for manufacturing molten irons using the same - Google Patents

Abstract

The present invention relates to a method for producing molten iron by blowing a hydrocarbon-containing gas and an apparatus for producing molten iron using the same. In the molten iron manufacturing method according to the present invention, the step of reducing the iron ore in a reducing furnace to convert to a reducing body, the step of forming a coal filling layer by charging the bulk coal material in the molten gasifier connected to the reducing furnace, the oxygen-containing gas coal filling layer Forming a combustion zone by blowing into the combustion zone, generating a reducing gas by burning the bulk carbon material in the combustion zone, and injecting hydrocarbon-containing gas directly into the combustion zone after the combustion zone is formed to further generate a reduction gas, and reducing Charging the sieve to a melting gasifier and contacting with a reducing gas to melt the sieve.

Hydrocarbon-containing gas, blown, melt gasification furnace, steam

Description

METHOD FOR MANUFACTURING MOLTEN IRONS BY INJECTING A HYDROCARBON GAS AND APPARATUS FOR MANUFACTURING MOLTEN IRONS USING THE SAME}

1 is a view schematically showing a molten iron manufacturing apparatus according to a first embodiment of the present invention.

2 is a view showing in detail the tuyere of FIG.

3 is a view schematically showing a state in which a combustion zone is formed in the apparatus for manufacturing molten iron of FIG. 1.

4 is a view schematically showing the tuyere included in the apparatus for manufacturing molten iron according to the second embodiment of the present invention.

5 is a view schematically showing a molten iron manufacturing apparatus according to a third embodiment of the present invention.

6 is a graph showing a change in molten iron production amount according to the experimental example of the present invention and the comparative example of the prior art.

7 is a graph showing a change in the reducing agent ratio according to the experimental example of the present invention and the comparative example of the prior art.

8 is a graph showing a change in molten iron production amount and reducing lot according to the experimental example of the present invention and the comparative example of the prior art.

9 is a graph showing a change in combustion zone temperature according to the experimental example of the present invention and the comparative example of the prior art.

10 is a graph showing a change in the molten iron temperature according to the experimental example of the present invention and the comparative example of the prior art.

11 is a graph showing a change in the amount of Si in molten iron according to the experimental example of the present invention and the comparative example of the prior art.

The present invention relates to a method for producing molten iron by blowing a hydrocarbon-containing gas and a molten iron manufacturing apparatus using the same, and more particularly, to generate a high-quality reducing gas required to melt a reduced iron by injecting a hydrocarbon-containing gas into a molten gas furnace. It relates to a molten iron manufacturing method and a molten iron manufacturing apparatus using the same.

The steel industry is a key industry that supplies basic materials to the entire industry, such as automobiles, shipbuilding, home appliances, construction, etc., and is one of the oldest industries with the development of mankind. Steel mills, which play a pivotal role in the steel industry, use molten iron and coal as raw materials to produce molten pig iron, which is then manufactured and supplied to each customer.

Currently, about 60% of the world's iron production comes from blast furnace methods developed since the 14th century. Blast furnace method is a method of manufacturing molten iron by reducing the iron ore to iron by putting together the coke prepared from the sintering process and the coke produced from the bituminous coal into the blast furnace. However, the blast furnace method requires a supplementary facility for the production of coke and sintered ore, and there is a serious problem of environmental pollution due to the supplementary facility.

In order to solve the problems of the blast furnace method, many countries around the world are putting a lot of effort into the development of the molten reduction steelmaking method. In the molten reducing steelmaking method, molten iron is produced in a molten gas furnace using direct coal as a fuel and a reducing agent, and ore directly as an iron source. Here, oxygen is blown through a plurality of tuyere provided on the outer wall of the melt gasifier to burn the coal-filled layer in the melt gasifier. Oxygen is converted to high-temperature reducing gas and sent to a reduction furnace to reduce iron ore and discharged to the outside.

Coal such as lump coal or coal briquettes is charged into the melt gasifier. The cost of manufacturing depends on the amount of coal loaded. Therefore, in order to minimize the amount of coal charged, iron ore with high reduction rate should be charged into the melt gasifier. To this end, it is necessary to supply high quality reducing gas to the reduction furnace to maximize the reduction rate of iron ore.

Iron ore may be reduced by using hydrogen (H ₂ ) and carbon monoxide (CO) contained in the reducing gas. Therefore, a large amount of hydrogen and carbon monoxide should be generated in a melt gasifier in which reducing gas is generated. In order to generate a large amount of reducing gas as described above, there is a problem of burning more coal fuel than necessary in a melt gasifier.

Further, since pure oxygen is blown into the molten gasifier, the temperature of the combustion zone where char or coke is burned is as high as about 4000 ° C. Thus, since the temperature of a combustion zone is high, excessive heat load is given to the lower part of a melting gasifier. Therefore, the tuyere that injects pure oxygen is often melted and damaged. In addition, there is a problem that the refractory portion of the furnace portion is damaged to shorten the life of the melt gasification furnace.

The present invention is to solve the above-mentioned problems, to provide a molten iron manufacturing method that can improve the quality while blowing the hydrocarbon-containing gas to increase the amount of reducing gas.

In addition, the present invention is to provide a molten iron manufacturing apparatus using the above-described molten iron manufacturing method.

In the molten iron manufacturing method according to the present invention, the step of reducing the iron ore in a reducing furnace to convert to a reducing body, the step of forming a coal filling layer by charging the bulk coal material in the molten gasifier connected to the reducing furnace, the oxygen-containing gas coal filling layer Forming a combustion zone by blowing into the combustion zone, generating a reducing gas by burning the bulk carbon material in the combustion zone, and injecting hydrocarbon-containing gas directly into the combustion zone after the combustion zone is formed to further generate a reduction gas, and reducing Charging the sieve to a melting gasifier and contacting with a reducing gas to melt the sieve.

In the step of further generating the reducing gas, the blowing flow rate of the hydrocarbon-containing gas is preferably smaller than the blowing flow rate of the oxygen-containing gas.

The ratio of the blowing flow rate of the oxygen-containing gas to the blowing flow rate of the hydrocarbon-containing gas is preferably 1.5 to 3.0.

In the step of further generating the reducing gas, the hydrocarbon-containing gas is preferably blown into the molten gasification furnace spaced apart from the oxygen-containing gas.

Oxygen-containing gas is blown into the molten gasifier through a blowhole installed in the molten gasifier, and the hydrocarbon-containing gas is discharged from the blowing hole diameter (Φ) of the blowhole into which the oxygen-containing gas is blown and the blowing position of the hydrocarbon-containing gas in the molten gasifier. The horizontal distance F to the ignition start position preferably satisfies 7.0 ≦ F / Φ ≦ 14.0.

In the further generating of the reducing gas, the hydrocarbon-containing gas is blown into the combustion zone through a lance installed in the melt gasifier, and the flow rate of the hydrocarbon-containing gas at the lance outlet is greater than that of the hydrocarbon-containing gas at the lance inlet. It is preferable.

In the step of forming the combustion zone, it is preferable to supply a mixture of steam to the oxygen-containing gas.

The steam is blown into the molten gasifier through an air vent installed in the molten gasifier together with the oxygen-containing gas, and the angle formed by the steam and the oxygen-containing gas at the starting point of mixing is preferably 18 ° to 26 °.

The steam is mixed with the oxygen-containing gas before being blown into the molten gas furnace, and the diameter of the air vent in which the oxygen-containing gas is blown (Φ), and the diameter of the lance for blowing the hydrocarbon-containing gas apart from the oxygen-containing gas (d). It is preferable that the horizontal distance L from the injection position of the molten gasifier of the oxygen-containing gas to the starting position of mixing the vapor and the oxygen-containing gas satisfies 10.0 ≦ L / (Φ + d) ≦ 20.0.

In the further generation of the reducing gas, the hydrocarbon-containing gas includes liquid natural gas (LNG), liquid petroleum gas (LPG), blast furnace gas (BFG) and coke oven gas ( It is preferable to include at least one gas selected from the group consisting of cokes oven gas (COG).

The molten iron manufacturing method according to the present invention may further comprise the step of supplying the reducing gas generated in the molten gasifier to the reduction furnace.

The apparatus for manufacturing molten iron according to the present invention is a reduction furnace for reducing iron ore and converting it into a reducing body, and a melting gas furnace for forming a coal-filled layer by charging a reducing body and charging a bulk coal material therein in connection with a reducing furnace to form molten iron. It includes. Oxygen-containing gas is blown into the coal-filled bed to form a combustion zone to generate reducing gas.After formation of the combustion zone, hydrocarbon-containing gas is directly blown into the combustion zone to generate additional reducing gas, and the reducing gas is brought into contact with the reducing body. To prepare molten iron.

The blowing flow rate of the hydrocarbon-containing gas is preferably smaller than the blowing flow rate of the oxygen-containing gas.

The ratio of the blowing flow rate of the oxygen-containing gas to the blowing flow rate of the hydrocarbon-containing gas is preferably 1.5 to 3.0.

The melt gasifier further includes a tuyere provided on its side, and the tuyere preferably includes a through hole for injecting oxygen-containing gas into the melt gasifier and a lance spaced apart from the through hole to blow hydrocarbon-containing gas into the melt gasifier. .

The inner diameter of the lance outlet through which the hydrocarbon-containing gas exits is preferably smaller than the inner diameter of the lance inlet through which the hydrocarbon-containing gas flows.

It is preferable that the inner diameter of the lance gradually narrows along the direction in which the hydrocarbon-containing gas flows near the lance outlet, and then remains the same as the lance exits.

In the tuyere, the horizontal diameter (F) from which the oxygen-containing gas is blown into the molten gasifier and the blowing position of the hydrocarbon-containing gas into the molten gasifier is set to 7.0 ≤ F / Φ ≤ It is preferable to satisfy 14.0.

The tuyere is preferably connected with a steam blowing pipe for blowing steam.

The steam is mixed with the oxygen-containing gas before being blown into the melt gasifier, and the angle at which the steam is mixed with the oxygen-containing gas is preferably 18 ° to 26 °.

The vapor is mixed with the oxygen-containing gas before being blown into the molten gasifier, and the vapor from the blow-in diameter (Φ) of the tuyere through which the oxygen-containing gas is blown, the diameter of the lance (d), and the injection position in the molten gasifier of the oxygenous gas. And the horizontal distance L to the starting point of mixing of the oxygen-containing gas satisfies 10.0 ≦ L / (Φ + d) ≦ 20.0.

The molten iron manufacturing apparatus according to the present invention may further include a reducing gas supply pipe for supplying the reducing gas generated in the melt reduction furnace to the reduction furnace.

The reduction furnace is preferably a fluidized bed reduction furnace.

It is preferable that the reduction furnace is a packed-bed reduction furnace.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 5. These examples are merely to illustrate the invention, but the invention is not limited thereto.

1 shows a molten iron manufacturing apparatus 100 according to a first embodiment of the present invention. The apparatus for manufacturing molten iron 100 shown in FIG. 1 is merely for illustrating the present invention, but the present invention is not limited thereto. Therefore, the apparatus for manufacturing molten iron 100 may be modified in another form.

The molten iron manufacturing apparatus 100 shown in FIG. 1 includes a reduction furnace 30 and a melt gasification furnace 60. In addition, other devices may be included as needed. In the reduction furnace 30 is charged by reducing the iron ore. Subsidiary materials may be used as needed. Iron ore to be charged into the reduction furnace 30 is pre-dried in the form of a block. Iron ore is converted into a reducing body while passing through the reduction furnace (30). Reduction furnace 30 is a packed-bed reduction reactor, receives a reducing gas from the molten gasifier 60 to form a packed bed therein. Iron ore passes through a packed bed and is converted into a reducing body.

The bulk carbonaceous material is charged from the upper portion of the melt gasifier 60 to form a coal filling layer therein. The bulk coal material includes lump coal or coal briquettes. Coal briquettes are manufactured by press-molding pulverized coal. In addition, coke may be charged as needed. On the outer wall of the melt gasifier 60, a plurality of tuyere 80 is provided to blow in the oxygen-containing gas and the hydrocarbon-containing gas. Oxygen-containing gas means a gas containing oxygen and may use pure oxygen at room temperature. Oxygen-containing gas is blown into the coal packed bed to form a combustion zone. The bulk coal ash may be burned in a combustion zone to generate a reducing gas.

Hydrocarbon-containing gas means any gas containing hydrocarbons. For example, liquefied natural gas (LNG), liquefied petroleum gas (LPG), blast furnace gas (BFG) and coke oven gas (COG) may be used. have. Therefore, one or more gases selected from the group consisting of the aforementioned hydrocarbon-containing gases may be selected and used.

When the hydrocarbon-containing gas is blown into the melting gasifier, the amount of generation of reducing gas required for the reduction of iron ore increases. One example of the hydrocarbon-containing gas may be the LNG described above. When the same amount of LNG and coal is charged into the melting gasifier, the gas generation amount is shown in Table 1 below.

As shown in Table 1, LNG generates about 2.2 times as much reducing gas as coal. In particular, the hydrogen component in the reducing gas is greatly increased. Hydrogen has three times more reducing power than carbon monoxide. Therefore, when the hydrocarbon-containing gas is blown into the melt gasifier, a good amount of reducing gas can be obtained.

When a large amount of high quality reducing gas is supplied to the reduction furnace, the reduction rate of reduced iron in the reduction furnace increases, thereby reducing the additional reduction burden of reduced iron in the melt gasifier. Therefore, the reducing agent ratio is reduced. And under constant reduction rate conditions, reduced iron production increases. Therefore, the amount of heat loss through the furnace body in the melt gasification furnace is reduced, reducing the cost of the reducing agent according to the molten iron production.

The reduced body reduced in the reduction furnace 30 is charged through the upper part of the melt gasifier 60 and melted while passing through the coal filling layer. The reducing body is melted in direct contact with the reducing gas. This method can be used to produce molten iron. A hot water outlet is installed in the lower portion of the melt gasifier 60 to discharge molten iron and slag to the outside.

A reducing gas containing hydrogen and carbon monoxide is generated from the coal-filled layer formed inside the melt gasifier 60. Since the upper portion of the melt gasifier 60 is formed in a dome shape, it is advantageous to generate a reducing gas. The reducing gas discharged from the melt gasifier 60 is supplied to the reduction furnace 30 through a reducing gas supply pipe 70. Therefore, iron ore can be reduced and calcined by a reducing gas. Although FIG. 1 shows that the reducing gas is supplied to the reduction furnace 30, the reducing gas may be directly supplied to the reduction furnace 30 from another apparatus.

As shown in FIG. 2, the oxygen-containing gas and the hydrocarbon-containing gas can be blown through the tuyere 80 provided in the aforementioned melt gasifier 60. 2 shows a cross-sectional structure of the tuyere 80. In addition, the lance 603 shown in FIG. 2 has a predetermined thickness. The structure of the tuyere 80 shown in FIG. 2 is merely for illustrating the present invention, and the present invention is not limited thereto. Therefore, the structure of the tuyere 80 can be modified in various forms.

A plurality of cooling conduits 605 are formed inside the tuyere 80 to cool the tuyere 80. Therefore, the air vent 80 exposed to the high temperature inside of the melt gasification is prevented from being damaged.

The oxygen-containing gas is blown into the molten gasifier through the through hole 601 of the tuyere 80. On the other hand, the hydrocarbon-containing gas is blown into the molten gasifier through the lance 603 of the tuyere 80. The hydrocarbon-containing gas is blown into the molten gasifier in a state spaced apart from the oxygen-containing gas. In the case where the hydrocarbon-containing gas and the oxygen-containing gas are pre-mixed and charged, the hydrocarbon-containing gas is ignited by the oxygen-containing gas to generate high heat.

That is, since oxygen has high oxidative property, the temperature of a combustion zone is about 4,000 degreeC high. Radiation heat due to the high temperature may burn hydrocarbon-containing gas inside the tuyere, causing the tuyere to be melted. In order to prevent this phenomenon, the hydrocarbon-containing gas and the oxygen-containing gas are separated and blown into the molten gasifier. Since the hydrocarbon-containing gas is blown through the lance 603, the hydrocarbon-containing gas and oxygen do not meet each other inside the tuyere. According to this structure, the heat load of the end portion 6011 of the tuyere 80 can be greatly reduced, so that the hydrocarbon-containing gas can be stably blown into the combustion zone.

As shown in FIG. 2, the hydrocarbon-containing gas flows through the lance 603. The hydrocarbon-containing gas flows in through the inlet of the lance 603, and the hydrocarbon-containing gas flows out through the outlet of the lance 603. Here, the inner diameter of the lance 603 outlet is smaller than the inner diameter of the lance 603 inlet. Since the lance 603 has such a structure, the dependence of the hydrocarbon-containing gas when the hydrocarbon-containing gas passes through the lance 603 becomes larger than the initial velocity of the hydrocarbon-containing gas. Accordingly, the blowing flow rate of the hydrocarbon-containing gas at the outlet of the lance 603 can be further increased while minimizing the pressure loss caused by the high-speed hydrocarbon-containing gas. Since the dependency of the hydrocarbon-containing gas becomes larger than its initial velocity, the hydrocarbon-containing gas can be easily blown into the melt gasification furnace.

In order to more smoothly flow the hydrocarbon-containing gas, the lance 603 preferably has a shape as shown in FIG. That is, the inner diameter of the lance 603 gradually narrows along the direction in which the hydrocarbon-containing gas flows near the outlet of the lance 603. Again, the inner diameter of the lance 603 remains the same toward the exit side of the lance 603.

As shown in Fig. 2, the hydrocarbon-containing gas is directly blown into the combustion zone formed by the oxygen-containing gas. That is, the hydrocarbon-containing gas is blown directly into the combustion zone without being mixed with the oxygen-containing gas in the tuyere 80. Hydrocarbon-containing gases blown directly into the combustion zone are burned and reformed directly in the combustion zone. Therefore, it is possible to further generate a reducing gas containing a large amount of heat required for melting the reducing body and hydrogen required for reduction.

Oxygen-containing gas is first blown into the melting gasifier to combust the char forming the coal packed bed. Since the flow rate of the oxygen-containing gas is about 170 m / s to 230 m / s, the kinetic energy of the oxygen-containing gas pushes down the coal shocks falling in front of the tuyere. Therefore, a combustion zone is formed in front of the tuyere. The combustion zone is an empty space, and coal coal is mainly burned around the combustion zone. Oxygen contained in the oxygen-containing gas generates heat by the reaction of the following formula (1) in the combustion zone formed in front of the tuyere (80).

That is, 1 kg of carbon reacts with an equivalent amount of oxygen to generate 2,200 kcal of heat. By this carbon combustion heat, the temperature of the combustion zone in a melt gasification furnace is as high as about 4,000 degreeC. Since the temperature of the combustion zone is so high, the tip of the tuyere may be melted and damaged, and the refractory installed inside the molten gas may be damaged. In addition, the content of silicon as an impurity in molten iron may increase.

However, in the first embodiment of the present invention, since the hydrocarbon-containing gas is directly blown into the combustion zone, the temperature of the combustion zone can be lowered, thereby preventing the aforementioned problem. Hydrocarbons contained in the hydrocarbon-containing gas blown into the combustion zone are decomposed as shown in the following formula (2).

The hydrocarbon-containing gas blown into the melt gasifier is decomposed into carbon and hydrogen through the formula (2). In this case, it absorbs a large amount of heat of about 1,380 kcal per kg of CH ₄ . Therefore, the temperature of a combustion zone can be reduced to 3,000 degrees C or less. Therefore, the tuyere and refractory can be protected and the quality of molten iron can be improved.

Oxygen-containing gas is blown at a higher rate than hydrocarbon-containing gas to form a combustion zone. In other words, the blowing flow rate of the hydrocarbon-containing gas is smaller than the blowing flow rate of the oxygen-containing gas. Therefore, once the reducing gas is generated by the oxygen-containing gas, the reducing gas can be additionally generated by the hydrocarbon-containing gas.

The ratio of the blowing flow rate of the oxygen-containing gas to the blowing flow rate of the hydrocarbon-containing gas is maintained at 1.5 to 3.0. If the ratio is less than 1.5, since the hydrocarbon-containing gas and the oxygen-containing gas are blown together, ignition may occur and the end portion 6011 of the tuyere 80 may melt and be damaged. On the contrary, if this ratio exceeds 3.0, combustion may be incompletely affected by the formation of the combustion zone.

3 schematically shows a state in which the tuyere 80 shown in FIG. 2 operates. The operating state of the tuyere 80 shown in FIG. 3 is merely for illustrating the present invention, and the present invention is not limited thereto.

As shown in FIG. 3, a combustion zone is formed in the coal shockbed by the oxygen-containing gas supplied through the tuyere 80 to generate a reducing gas. In addition, the hydrocarbon-containing gas supplied through the tuyere 80 is directly blown into the combustion zone to further generate a reducing gas.

In order to efficiently reform the hydrocarbon-containing gas in the combustion zone, the angle θ and the combustion focal length F must be properly adjusted. Angle (theta) means the angle which an oxygen containing gas and a hydrocarbon containing gas make at the time of blowing in. The combustion focal length F means the horizontal distance from the blowing position (a) of the hydrocarbon-containing gas into the molten gasifier to the ignition starting position (b) of the hydrocarbon-containing gas. That is, it means the horizontal distance from which the combustion of hydrocarbon gas occurs from the end of the tuyere. Here, the horizontal distance is not a distance measured between the blowing position (a) and the ignition start position (b), but means a distance perpendicular to the direction of gravity.

The angle θ can be appropriately adjusted by adjusting the lance 603. If the angle θ is too large, the combustion focal length F becomes too short and the heat load on the tuyere increases. If the angle θ is too small, the combustion focal length F becomes too long and the ignition of the hydrocarbon-containing gas is delayed. The magnitude of the angle θ varies with the diameter of the tuyere. In FIG. 3, the aperture diameter Φ means the diameter of the through hole 601 when the oxygen-containing gas is blown into the molten gas furnace in the aperture 80.

Here, it is preferable that F / (phi) is 7.0 or more and 14.0 or less. The reforming efficiency can be optimized in this range. The units of F and Φ are all mm. If the F / Φ is less than 7.0, the tuyere may be heated to damage the tuyere. In addition, when F / Φ exceeds 14.0, hydrocarbon-containing gas is not completely reformed in the combustion zone and exits the combustion zone.

4 schematically shows the structure of the gas blowing device 90 included in the apparatus for manufacturing molten iron according to the second embodiment of the present invention. The structure of the gas blowing device 90 shown in FIG. 4 is merely for illustrating the present invention, and the present invention is not limited thereto. In addition, since the tuyere 80 included in the gas blowing device 90 is the same as the tuyere included in the molten iron manufacturing apparatus according to the first embodiment of the present invention described above, the same reference numerals are used.

The gas blowing device 90 shown in FIG. 4 includes a steam blowing pipe 701. The vapor is mixed with the oxygen containing gas before blowing into the melt gasifier. By mixing the steam with the oxygen-containing gas blown there is no need to install a separate steam blowing pipe for blowing the steam in the tuyere (80). Therefore, the structure of the tuyere 80 can be made simple. The oxygen-containing gas is supplied into the molten gasifier through the blow pipe 703, so that it is well mixed with the steam.

The steam is in direct contact with the hydrocarbon containing gas in the combustion zone to promote the reforming reaction of the hydrocarbon containing gas. This reforming reaction is shown in the following formula (3). Here, CH ₄ is the main component of the hydrocarbon-containing gas.

As described in Formula 3, the vapor is in contact with the hydrocarbon-containing gas and decomposes into carbon monoxide and hydrogen, causing an endothermic reaction that absorbs ambient heat. The endothermic reaction consumes 228,000 kJ of heat per mol of CH ₄ . By the endothermic reaction, the temperature of the combustion zone can be reduced. Therefore, it is possible to prevent the combustion zone from being deteriorated or spoiled by reducing the heat load applied to the inner wall by the air vent 80 and the melt gasification.

The above-described contact phenomenon of the vapor and the hydrocarbon-containing gas will be described in more detail by using chemical formulas as follows.

As described in Formula 4 above, the vapor serves as an initiator of the hydrocarbon containing gas. That is, steam converts the carbon of the hydrocarbon-containing gas into carbon monoxide. Carbon monoxide and hydrogen produced by the reaction of hydrocarbon-containing gases with steam are burned in a combustion zone into carbon dioxide and water. Carbon dioxide and water exit the combustion zone and pass through the coal bed bed, where they react with coal to convert it back to carbon monoxide and hydrogen.

Reducing gas containing carbon monoxide and hydrogen rises in the melting gasifier to remove oxygen remaining in the reducing body to completely reduce the reducing body. In particular, the reducing gas rises while passing through the inner bed of the melt gasification furnace. In this case, a large amount of heat is transferred from the bottom of the furnace to the top of the furnace, and the reducing gas is sent to a reduction furnace to further increase the reduction rate of iron ore. Therefore, for example, the reduction rate of iron ore can be adjusted to about 70% to 80%. In particular, since steam generates about three times as much hydrogen as carbon monoxide having excellent reducing power than carbon monoxide, it is advantageous for reducing iron ore.

As shown in Fig. 4, the vapor is mixed with the oxygen-containing gas before being blown into the melt gasification furnace. Since the oxygen-containing gas may be at room temperature, moisture must be blown into the vapor state to prevent damage to the equipment due to condensation of water. Moreover, steam may also condense in the blow pipe 703 or the tuyere 80. In this case, water lowers the high velocity flow of the oxygen-containing gas. Therefore, pressure loss of the entire gas blowing device 90 may occur, and the air vent 80 may be damaged by the combustion zone. Therefore, it is necessary to adjust the installation position appropriately so that steam does not condense.

As shown in FIG. 4, the angle α formed when the vapor is mixed with the oxygen-containing gas is preferably 18 ° to 26 °. In the case where the vapor intake pipe 701 is provided in the blow pipe 703, it is impossible to make the angle α less than 18 ° by design. In addition, when the angle α exceeds 26 °, the vapor may be condensed by interrupting the flow of the oxygen-containing gas. Therefore, it is preferable to keep the angle α in the above-described range.

In Fig. 4, the horizontal diameter L from the blowing position (c) in the molten gasifier of the oxygen-containing gas to Φ, the diameter of the lance, d, and the lance diameter of the lance. It is desirable to satisfy a certain relationship. That is, it is preferable that L / (Φ + d) is 10.0 or more or 20.0 or less.

If L / (Φ + d) is less than 10.0, the vapor and the oxygen-containing gas are not mixed well. In addition, when L / (Φ + d) exceeds 20.0, the steam is condensed in the process of mixing the blown steam and oxygen. Therefore, it is necessary to adjust the installation position of the steam blown pipe 701 to satisfy the above-mentioned range.

5 shows a molten iron manufacturing apparatus 300 according to a third embodiment of the present invention. The molten gasifier 60 shown in FIG. 5 is the same as the molten gasifier shown in FIG. 1, and the same reference numerals are used for convenience and detailed description thereof will be omitted.

The apparatus for manufacturing molten iron 300 includes one or more flow reduction reactors 20, a melt gasifier 60, a reducing gas supply pipe 70, and a compacted material manufacturing apparatus 40. In addition, the high temperature homogenizing device 50 for transferring the compacted material manufactured by the compacted material manufacturing apparatus 40 to the melt gasifier 60 may be further included. The high temperature uniform pressure-reducing apparatus 50 presses the compacted body manufactured by the compacted body manufacturing apparatus 40 to the molten gasifier 60. The compacted material manufacturing apparatus 40 and the high temperature uniform back pressure apparatus 50 can be omitted as needed.

The apparatus for manufacturing molten iron 300 may use iron ore. Subsidiary materials may be used as needed. A fluidized bed is formed inside the fluid reduction path 20 to reduce iron ore. The flow reduction path 20 includes a first flow reduction path 201, a second flow reduction path 203, a third flow reduction path 205, and a fourth flow reduction path 207. Although four flow reduction paths 20 are shown in FIG. 5, these are merely to illustrate the present invention and the present invention is not limited thereto. Therefore, three flow reduction reactors may be used.

The first flow reduction path 201 preheats the iron ore with reducing gas discharged from the second flow reduction path 203. The second flow reduction path 203 and the third flow reduction path 205 preliminarily reduce the preheated iron ore. The fourth flow reduction reactor 207 finally converts the preliminarily reduced iron ore into a reducing body.

Iron ore is reduced and heated while passing through the fluid reduction path (20). To this end, the reducing gas generated in the melt gasifier 60 is supplied to the flow reduction path 20 through the reducing gas supply pipe (70). The reduced iron ore is made of compacted material through the compacted material manufacturing apparatus 40.

The compacted material manufacturing apparatus 40 includes the charging hopper 401, a pair of roll 403, the crusher 405, and the storage tank 407. In addition, other devices may be further included as necessary. The charging hopper 401 stores the reduced iron ore while flowing through the flow reduction path 20. Iron ore is press-molded in the form of a strip while being charged from the charging hopper 401 into a pair of rolls 403. The iron ore press-molded in this manner is crushed in the crusher 405 and stored as a compact in the storage tank 407.

Hereinafter, the present invention will be described in more detail through experimental examples. Such experimental examples of the present invention are merely for illustrating the present invention, and the present invention is not limited thereto.

In the experimental example of the present invention, molten iron was manufactured using the molten iron manufacturing apparatus shown in FIG. 5. 26 vents were installed on the side wall of the molten iron manufacturing apparatus, and the diameter of the vents was 23 mm. The molten iron was 2500 tp / d and the blowing oxygen was 36,000 m ³ / hr. The combustion zone temperature in the melt gasifier was 3,850 ° C. before the liquefied natural gas blowing. Molten gas was blown into a molten gas furnace to prepare molten iron.

The experimental conditions of the comparative example of the prior art are the same as the experimental conditions of the experimental example of the present invention described above except for blowing of liquefied natural gas.

Other detailed manufacturing method for molten iron can be easily understood by those skilled in the art, detailed description thereof will be omitted. The experimental results according to the experimental example and the comparative example are as follows.

Molten iron production and reducing agent

As shown in FIG. 6, in the experimental example, the daily production of molten iron was 2250 tons, whereas in the comparative example, the daily production of molten iron was 2100 tons. Therefore, in the case of the experimental example, the molten iron production was increased by 150 tons compared with the comparative example. That is, in the experimental example, the production of reduced iron having a constant reduction rate increased by increasing the amount of hydrogen generated in the melt gasification furnace by blowing the LNG.

On the other hand, as shown in Figure 7, in the case of the experimental example it took 790kg to produce 1 ton of molten iron. On the other hand, in the comparative example, the reducing agent required 850 kg to produce 1 ton of molten iron. Therefore, the experimental example was able to use 60kg less reducing agent than the comparative example. This is due to the decrease in the amount of heat dissipated through the furnace body into the molten gasifier as the production of molten iron increases.

8 is a graph showing the above-described molten iron production amount and reducing agent ratio together. In FIG. 8, the experimental example is indicated by ■, and the comparative example is indicated by ●. As shown in FIG. 8, the experimental example is mainly located at the lower right of FIG. 8. Therefore, it can be seen that the amount of molten iron is high while the reducing agent ratio is low. On the other hand, the comparative example is mainly located in the upper left of FIG. Therefore, it can be seen that while the reducing agent ratio is high, the molten iron production is small. Therefore, the experimental example can produce molten iron while minimizing the manufacturing cost compared to the comparative example.

9 and 10 show the molten iron temperature and the combustion zone temperature in the experimental and comparative examples, respectively. As shown in FIG. 9, in the experimental example, the molten iron temperature was 1495 ° C., whereas in the comparative example, the molten iron temperature was 1515 ° C. Therefore, in the case of the experimental example, it was found that the molten iron temperature is about 20 ℃ lower than the comparative example.

In addition, as shown in FIG. 10, the temperature range of the combustion zone was 3850 ° C in the experimental example, while the temperature of the combustion zone was significantly low at 3570 ° C in the comparative example. Therefore, the experimental example was 280 ℃ lower combustion zone temperature than the comparative example. As such, when the combustion zone temperature is lowered, the air vents are less damaged. That is, as the combustion zone temperature is lowered, the heat load at the tip of the tuyere is reduced. Therefore, the phenomenon that the tuyere melted and broken is eliminated, so that the operation is stabilized by melt gasification during LNG injection. In addition, it can be seen that the silicon content in molten iron decreases as the temperature of the combustion zone decreases. This will be described in more detail below with reference to FIG. 11.

As shown in FIG. 11, in the experimental example, [Si] in molten iron was as low as 0.9%. On the other hand, in the cited example, [Si] of molten iron was 0.4% more than the experimental example as about 1.3%. Injecting LNG as in Experimental Example stabilizes the molten iron temperature and the combustion zone temperature. (See FIG. 9 and FIG. 10) When the combustion zone temperature is lowered, the rate and amount of conversion of silica (SiO ₂ ) to SiO gas among the ash components in the furnace decreases. Therefore, as shown in the following formula (5), SiO gas is less likely to act on the molten iron.

If the content of silicon in the molten iron is high quality of molten iron, silicon in the molten iron should be removed in the steelmaking process. Therefore, the cost of manufacturing molten iron increases. Therefore, by injecting LNG as in Experimental Example, the quality of molten iron can be improved, thereby reducing the cost of manufacturing molten iron.

In the method for manufacturing molten iron according to the present invention, since the hydrocarbon-containing gas is blown, it is possible to produce a reducing gas having a high reducing power. Therefore, it is possible to significantly improve the reduction rate of iron ore can significantly reduce the molten iron manufacturing cost.

By using the heat of decomposition of the hydrocarbon-containing gas, it is possible to prevent excessive rise in temperature at the bottom by melt gasification. In addition, as the hydrocarbon-containing gas is decomposed, a large amount of gas is released, thereby efficiently transferring heat from the lower part to the upper space of the coal filling layer by melting gasification.

Although the present invention has been described above, it will be readily understood by those skilled in the art that various modifications and variations are possible without departing from the spirit and scope of the claims set out below.

Claims (24)

Converting the iron ore into a reducing body by reducing it in a reduction furnace, Charging a bulk carbonaceous material into a molten gasifier connected to the reduction furnace to form a coal filling layer; Blowing an oxygen-containing gas into the coal packed bed to form a combustion zone, Burning the mass carbon material in the combustion zone to generate a reducing gas; Generating a reducing gas by directly injecting a hydrocarbon-containing gas directly into the combustion zone after the combustion zone is formed; and Charging the reducing body into the melting gasifier and contacting the reducing gas to melt Iron manufacturing method comprising a. In claim 1, In the step of generating the reducing gas further, the blowing flow rate of the hydrocarbon-containing gas is less than the blowing flow rate of the oxygen-containing gas manufacturing method. In claim 2, And a ratio of the blowing flow rate of the oxygen-containing gas to the blowing flow rate of the hydrocarbon-containing gas is 1.5 to 3.0. In claim 1, In the step of generating the reducing gas further, the hydrocarbon-containing gas is blown into the molten gas furnace in a state spaced apart from the oxygen-containing gas. In claim 4, The oxygen-containing gas is blown into the molten gasifier through a tuyere provided in the molten gasifier, and the air passage diameter Φ of the tuyere through which the oxygen-containing gas is blown, and into the molten gasifier of the hydrocarbon-containing gas. The horizontal distance (F) from the blowing position to the ignition start position of the hydrocarbon-containing gas satisfies the following formula. 7.0 ≤ F / Φ ≤ 14.0 In claim 1, In the step of further generating the reducing gas, the hydrocarbon-containing gas is blown into the combustion zone through a lance installed in the melt gasifier, and the flow rate of the hydrocarbon-containing gas at the lance outlet is at the inlet of the lance. A molten iron manufacturing method which is larger than the flow velocity of the said hydrocarbon containing gas. In claim 1, In the forming of the combustion zone, the molten iron manufacturing method for supplying a mixture of steam to the oxygen-containing gas. In claim 7, The steam is blown into the molten gasifier through the air vent installed in the molten gasifier together with the oxygen-containing gas, and the angle between the steam and the oxygen-containing gas at the starting point of mixing is 18 ° to 26 °. Way. In claim 7, The vapor is mixed with the oxygen-containing gas before being blown into the molten gasifier, and blows the hydrocarbon-containing gas in a state spaced apart from the wind aperture diameter Φ of the tuyere through which the oxygen-containing gas is blown and the oxygen-containing gas. The diameter (d) of the lance and the horizontal distance (L) from the position where the oxygen-containing gas is blown into the molten gasifier from the mixing start position of the steam and the oxygen-containing gas satisfy the following equation. . 10.0 ≤ L / (Φ + d) ≤ 20.0 In claim 1, In the further generation of the reducing gas, the hydrocarbon-containing gas is liquid natural gas (Liquid Natural Gas, LNG), liquefied petroleum gas (LPG), blast furnace gas (BFG) and coke oven A method of manufacturing molten iron comprising at least one gas selected from the group consisting of coke oven gas (COG). In claim 1, The molten iron manufacturing method further comprises the step of supplying the reducing gas generated in the gasifier to the reduction furnace. A reduction furnace for reducing iron ore to a reducing body, and The reducing gas is connected to the reduction furnace, the reducing body is charged, and the bulk carbon material is charged therein to form a coal-filled layer to produce molten iron. Including, Oxygen-containing gas is blown into the coal-filled bed to form a combustion zone to generate a reducing gas.After formation of the combustion zone, a hydrocarbon-containing gas is directly blown into the combustion zone to further generate a reducing gas. A molten iron manufacturing apparatus for producing the molten iron in contact with the reducing body. In claim 12. And a blowing flow rate of the hydrocarbon-containing gas is smaller than a blowing flow rate of the oxygen-containing gas. The method of claim 13, And a ratio of the blowing flow rate of the oxygen-containing gas to the blowing flow rate of the hydrocarbon-containing gas is 1.5 to 3.0. In claim 12, The molten gasifier further comprises a tuyere provided on its side, the tuyere is a through hole for blowing the oxygen-containing gas into the molten gasifier, and the hydrocarbon-containing gas is blown away from the through-hole to the molten gasifier A molten iron manufacturing apparatus comprising a lance. 16. The method of claim 15, And an inner diameter of the lance outlet through which the hydrocarbon-containing gas flows out is smaller than an inner diameter of the lance inlet through which the hydrocarbon-containing gas flows. The method of claim 16, The inner diameter of the lance is gradually narrowed along the flow direction of the hydrocarbon-containing gas in the vicinity of the lance exit and maintained again the same toward the outlet side of the lance. The method of claim 16, In the tuyere, the wind aperture diameter Φ in which the oxygen-containing gas is blown into the molten gasifier and the horizontal distance F from the injection position in the molten gasifier of the hydrocarbon-containing gas to the ignition start position of the hydrocarbon-containing gas are A molten iron manufacturing apparatus satisfying the following formula. 7.0 ≤ F / Φ ≤ 14.0 The method of claim 16, The tuyere is molten iron manufacturing apparatus connected with the steam blowing pipe for blowing steam. The method of claim 19, And the steam is mixed with the oxygen-containing gas before being blown into the molten gasifier, and the angle at which the steam is mixed with the oxygen-containing gas is 18 ° to 26 °. The method of claim 19, The vapor is mixed with the oxygen-containing gas before being blown into the molten gasifier, and the wind diameter (Φ) of the tuyere through which the oxygen-containing gas is blown, the diameter (d) of the lance, and the oxygen-containing gas. And a horizontal distance (L) from the injection position in the melt gasifier to the start position of mixing the vapor and the oxygen-containing gas satisfies the following equation. 10.0 ≤ L / (Φ + d) ≤ 20.0 In claim 12, The molten iron manufacturing apparatus further comprises a reducing gas supply pipe for supplying the reducing gas generated in the melt reduction furnace to the reduction furnace. In claim 12, The reduction furnace is a molten iron manufacturing apparatus is a fluidized bed reduction furnace. In claim 11, The reduction furnace is a molten iron manufacturing apparatus is a packed-bed reduction furnace.

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