KR101532668B1 - Burning apparatus and manufacturing method of reduced iron using the same - Google Patents

Abstract

The present invention relates to a firing apparatus and a method for manufacturing reduced iron using the same, the apparatus comprising: a first firing furnace for heating a briquette while moving a bogie loaded with briquettes along a linear movement path; A second baking furnace connected to the other side of the first baking furnace and heating the briquettes discharged from the bogie while moving along an annular moving path; And a cooling device connected to the second baking furnace and cooling the reduced iron reduced in the second baking furnace while moving the reduced iron along an annular movement path, wherein the exhaust gas generated in the baking furnace and the cooling device is circulated, The metalization rate of the reduced iron can be improved by controlling the concentration.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a burning apparatus and a method for manufacturing reduced iron using the same,

The present invention relates to a firing apparatus and a method for manufacturing reduced iron using the same, and more particularly, to a firing apparatus capable of improving the metallization ratio of reduced iron through control of temperature and oxygen concentration in a firing furnace, and a method for manufacturing reduced iron using the apparatus.

A typical reduced iron manufacturing apparatus includes a plurality of hoppers for receiving iron raw materials and carbonaceous materials, a crusher for receiving and crushing iron raw materials and carbonaceous materials, a mixer for mixing and supplying iron raw materials and carbonaceous materials, And a baking furnace for baking and baking the briquettes produced in the briquetting machine.

On the other hand, in the sintering furnace, reduced iron is produced by heat treatment and reduction. For this purpose, the baking furnace is normally closed and supplies carbon monoxide (CO) gas, carbon dioxide (CO ₂ ) or hydrogen (H) gas to induce a reducing atmosphere inside.

However, it takes a lot of time to prepare the inside of the calcining furnace in a reducing atmosphere, which makes it difficult to mass-produce the reduced iron.

Currently, about 60% of the world's iron production is produced from the blast furnace, which was developed from the 14th century. The blast furnace method is a method of manufacturing molten iron by adding sintered iron ore and cokes produced from bituminous coal as raw materials into a blast furnace and blowing hot air to reduce iron ore to iron.

Since the blast furnace process, which is a type of molten iron production facility, requires a raw material having a strength that is above a certain level and a particle size capable of ensuring ventilation in the furnace, the carbon source used for the fuel and the reducing agent It relies on coke treated with a specific coking coal, and it mainly relies on sintered ores that have undergone a series of agglomeration processes.

In order to smooth the flow of reducing gas in the blast furnace, the sintered ore, which made the iron ore into a lump state, and the coke which is made into the lump state by charging the analytical carbon are charged.

However, the contact area of the raw gas per unit volume of the sintered ore in the lump state is extremely small as compared with the case of the iron ore, and even after the reduction in the blast furnace is completed, the contact area with the carbon is small and it is difficult to permeate the carbon into the reduced iron. Therefore, the sintered ores have a high melting point, so they require a lot of energy to melt and have a fundamental problem that the production speed of the molten iron is slow.

There has been developed a process for manufacturing reduced iron directly by reducing iron in a rotary hearth furnace (RHF) by briquetting or pelletizing the iron ore minerals. However, in the case of direct reduced iron production, the output is in the range of 150,000 to 500,000 tons per year, and there is a limit to mass production and the reduction rate is over 95%, which is used as raw material for electric furnace.

In addition, a process for producing partially reduced iron by compacting minerals into briquettes or pellets and firing at a maximum temperature of 1,350 ° C. has been developed, and mass production of up to 4 million tons is possible. However, such a process has a problem in that the temperature and oxygen concentration in the calcining furnace are difficult to control because the process is carried out in an unsealed open burning furnace, and the metallization rate of the partially reduced iron is relatively low.

KR 2013-53089A KR 2013-116054A

The present invention provides a firing apparatus capable of controlling the temperature and oxygen concentration in a firing furnace to improve the metallization ratio of the partially reduced iron, and a method for manufacturing reduced iron using the firing apparatus.

The present invention also provides a firing apparatus capable of improving the energy efficiency by circulating the exhaust gas generated in the course of manufacturing partially reduced iron into the firing furnace, and a method for manufacturing reduced iron using the firing apparatus.

A firing apparatus according to an embodiment of the present invention is a firing apparatus for producing reduced iron by heating a briquette,
A first firing furnace for heating the briquettes while moving the bogie charged with the briquettes along a linear movement path;
A second baking furnace connected to the other side of the first baking furnace and heating the briquettes discharged from the bogie while moving along an annular moving path; And a cooling device connected to the second baking furnace and cooling the reduced iron reduced in the second baking furnace while moving the reduced iron along an annular movement path, wherein the first baking furnace is divided into a drying zone, a coal gasification zone and a preheating zone And the cooling device is divided into a first cooling region and a second cooling region, and includes a connection pipe communicating at least the coal gasification region and the first cooling region.

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And a connection pipe for communicating at least two of the drying region, the coal gasification region, the preheating region and the second cooling region with each other.

And an inlet pipe for supplying outside air to the first cooling area and the second cooling area.

The inlet pipe of the first cooling zone may be connected to a connection pipe connecting the coal gasification zone and the first cooling zone.

The coal gasification zone and the first cooling zone may communicate with each other.

The preheating zone, the second cooling zone and the coal gasification zone may be in communication with each other.

The connection pipe may connect the drying zone with the preheating zone.

A method of manufacturing reduced iron according to an embodiment of the present invention includes the steps of: preparing a shaped coal containing a carbonaceous material and an iron raw material; A step of heat treating the briquettes and firing the briquettes to produce reduced iron; And cooling the reduced iron. The exhaust gas generated in the coal gasification process for removing volatilization of the carbonaceous material contained in the briquette during the production of the reduced iron is used as a cooling gas for the reduced iron.

And a step of preheating the briquettes after the coal gasification process. The exhaust gas generated in the process of preheating the briquettes and the exhaust gas generated in the process of cooling the reduced iron are mixed and supplied to the coal gasification process, It can be heated.

The drying process for removing moisture contained in the briquettes before the coal gasification process is performed, and the drying process may use the exhaust gas generated in the process of preheating the briquettes as a heat source.
The process of cooling the reduced iron may include a first cooling process for cooling the reduced iron using the cooling gas for the exhaust gas generated in the coal gasification process and a reducing process using the reduced iron cooled in the first cooling process as the cooling gas And a second cooling process for cooling.

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In the second cooling process, a gas obtained by mixing the exhaust gas generated in the coal gasification process with the external air may be used as the cooling gas.

According to the embodiments of the present invention, it is possible to improve the process efficiency by easily controlling the oxygen concentration in the calcining furnace by producing the reduced iron by heating and cooling while moving the briquetted coal along the open firing furnace, the rotary firing furnace and the rotary cooling device, And the reduction ratio can be improved. In addition, the metalization rate of the partially reduced iron can be improved by circulating a part of the exhaust gas generated in the process of manufacturing the partially reduced iron to the inside of the sintering furnace and controlling the temperature and oxygen concentration in the sintering furnace. Further, the energy used to control the temperature inside the firing furnace can be saved, thereby reducing the production cost. In addition, materials such as carbon monoxide generated in the raw material constituting the partially reduced iron can be burned in the calcining furnace to improve the energy efficiency and to suppress environmental pollution.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the construction of a reduced iron manufacturing facility according to an embodiment of the present invention; FIG.
2 is a view schematically showing the structure of a firing apparatus according to an embodiment of the present invention.
3 is a block diagram showing the internal structure of the firing apparatus and the flow of the fluid according to the movement path of the briquette.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but is capable of other various forms of implementation, and that these embodiments are provided so that this disclosure will be thorough and complete, It is provided to let you know completely.

FIG. 1 is a block diagram showing the construction of a reduction iron manufacturing facility according to an embodiment of the present invention. FIG. 2 is a schematic view showing a structure of a firing apparatus according to an embodiment of the present invention, FIG. 3 is a block diagram showing the internal structure of the firing apparatus and the flow of the fluid.

First, the production method of reduced iron will be described as follows.

The reduced iron is produced by preparing and mixing a raw material to be used as an iron raw material and a reducing material, forming a mixture in which a mixture of the iron raw material and the carbonaceous material is mixed to produce a shaped coal, and then reducing the reduced carbon, . Here, the iron raw material may be at least one of iron ore as a reducing agent, iron oxide dust generated during a steelmaking process, and sludge. The carbonaceous material is a reducing material for reducing the iron raw material, and at least one of the coal dust and the carbon dust generated in the steelmaking process can be used. Here, the partially reduced iron means that the whole of Fe contained in the iron raw material, that is, 100% is not reduced but partially reduced to less than 100%. Of course, reduced iron reduced to 100% can be produced by controlling the firing time or the heat treatment temperature, but there is a problem that a burden is imposed on the firing apparatus in order to produce reduced iron having 100% reduction.

As shown in FIG. 1, the reduced iron manufacturing apparatus for producing reduced iron includes a plurality of hoppers 100 and 110 in which iron raw materials and carbonaceous materials are respectively received, and iron raw materials and carbonaceous materials from the hoppers 100 and 110, A mixer 300 for supplying and mixing the crushed iron raw materials and the carbonaceous material from the crusher 200, a molding machine 400 for molding the mixture mixed in the mixer 300, And a firing apparatus 500 for firing the formed briquettes by baking and cooling them. Although the iron source and the carbonaceous material are presented as raw materials for the briquette, additional materials such as a binder for facilitating the bonding between the iron source and the carbonaceous material and for improving the strength of the briquette can be additionally used. ). ≪ / RTI >

The molding machine 400 is a molding machine, that is, a twin roll molding machine, although it is not specifically shown, having a pair of rolls arranged to face each other. Thus, when the mixture is charged between the pair of rolls, the blast furnace is produced by extrusion due to the rotation of the pair of rolls.

The firing apparatus 500 heat-treats and reduces the briquettes produced in the briquetting machine 400 and cools the briquettes. For example, the briquetting apparatus 500 includes a heating unit having an internal space to heat and reduce the briquettes.

2 and 3, the firing apparatus 500 includes a first firing furnace 510 forming a straight path through which a bogie containing the briquettes therein is heated while moving from one side to the other, a first firing furnace 510, A second firing furnace 520 connected to the other side of the first firing furnace 510 to form an annular path for reducing and transferring the blanks discharged through the other side of the first firing furnace 510 and a second firing furnace 520 connected to the second firing furnace 520, And a cooling device 530 for forming an annular path for cooling the reduced iron discharged from the first and second heat exchangers 520 and 520.

The first firing furnace 510 has an inner space and is open at one side so that a bogie containing the briquettes therein enters. The other side of the first firing furnace 510 is connected to the second firing furnace 520. The bogie moves along the movement path of the endless track formed in a shape similar to that of the sintering apparatus and continuously moves the briquettes, and the first firing furnace 510 is formed to surround the upper side movement path of the movement path of the endless track shape . The first firing furnace 510 may be formed as a single space, but may be divided into a plurality of regions along the moving direction of the bogie. That is, as shown in FIGS. 2 and 3, the drying zone A, the coal gasification zone B, and the preheating zone C can be distinguished from the side where the truck enters. The inner space of the first firing furnace 510 can be divided into upper and lower flow passages 513a and 513b and upper and lower flow passages 514a and 514b and 514c and 514d respectively provided at upper and lower portions of the first firing furnace 510 . The upper flow passages 513a and 513b and the lower flow passages 514a, 514b, 514c and 514d may be formed in the same shape as a duct. The upper flow passages 513a and 513b and the lower flow passages 514a, 514b, 514c and 514d may be connected to each other by a plurality of connection pipes 517a, 517b, 517c and 517d communicating with each other. The connection pipes 517a, 517b, 517c and 517d are connected to the upper flow passages 513a and 513b and the lower flow passages 514a, 514b, 514c and 514d to communicate different regions of the first firing furnace 510 with each other Or may communicate with any one region of the first firing furnace 510 and the second firing furnace 520 or the cooling device 530. For example, the connecting pipes 517a, 517b, 517c and 517d connect the coal gasification zone B and the cooling unit (first cooling zone E1 described later) to each other by connecting 517a to the coal gasification zone B The exhaust gas can be supplied to the cooling device 530 and the preheating zone C and the drying zone A and the preheating zone C and the coal gasification zone B are interconnected 517d and 517c to form the preheating zone C Can be supplied to the drying region (A) and the coal gasification region (B), respectively. The connecting pipes 517a, 517b, 517c, and 517d may be provided with suction devices 515a, 515b, 515c, and 515d that generate a flow of gas to supply or discharge the exhaust gas generated in each region to other regions. The drying zone A of the first baking furnace 510 may be connected to a discharge pipe 511a for discharging exhaust gas generated while drying the briquettes.

The second firing furnace 520 is located at the other side of the first firing furnace 510, that is, at a portion where the moving direction of the bogie is changed, and the blanks discharged from the bogie are charged while the moving direction of the bogie is changed. The bins charged in the second firing furnace 520 are heated and reduced while moving along the annular movement path of the second firing furnace 520.

The second firing furnace 520 may be a kiln commonly referred to as a furnace. The second firing furnace 520 is formed such that a hearth having a body having an upper wall and side walls and forming an inner space and a bottom surface spaced apart from the upper wall inside the body is formed to move along the rails. At this time, the body is formed in an annular shape, and the hearth is provided to rotate along the inside of the annular body. A plurality of burners are provided on the side wall of the body to adjust the atmosphere and the temperature of the internal space of the body. In the second firing furnace 520 constructed as above, the briquettes discharged from the first firing furnace 510 are reduced. Here, the second firing furnace 520 is referred to as a reduction region D. The second firing furnace 520 is disposed downward to the cooling device 530 so that the exhaust gas generated in the second firing furnace 520 can flow smoothly into the preheating region C of the first firing furnace 510 It is possible.

The briquettes are reduced in the second firing furnace 520, discharged to the cooling device 530 connected to the second firing furnace 520, cooled, and then discharged to the outside. The cooling device 530 may be formed in substantially the same structure as the second firing furnace 520. However, the cooling device 530 can divide the internal space into two regions, so that the reduced iron produced in the second firing furnace 520 can be cooled in two steps. The inner space of the cooling device 530 is divided into a first cooling region E1 and a second cooling region E2 by partition walls or ducts 533a, 533b, 533c arranged in the vertical direction on the upper wall of the body . The first cooling zone E1 may be connected to a first inlet pipe 531 through which the outside air flows into the lower portion of the first cooling zone E1 and the first inlet pipe 531 may be connected to the coal gasification zone B of the first baking furnace 510, And the exhaust gas discharged from the coal gasification zone B can be mixed and supplied to the inside of the first cooling zone E1 as needed. The first inlet pipe 531 may be provided with a suction device 515e for sucking outside air. A second inlet pipe 532 through which the outside air flows may be connected to the second cooling zone E2 and a reduction pipe may be connected to the second cooling zone E2 through a lower outlet pipe 511b to cool the reduced iron, And the remainder may be supplied through connection pipes 517b and 517c connected to the coal gasification zone B.

The respective regions of the firing apparatus thus formed will be described as follows.

The drying zone (A) removes the moisture contained in the briquettes. In other words, moisture is contained in the inside of the molded container manufactured by the molding machine 400, and if it is suddenly heated to a high temperature close to the reducing temperature, the moisture inside the molded container evaporates and the molded container can be destroyed. In order to prevent this, in the drying region A, the molding is heated to a predetermined temperature, for example, about 200 to 300 ° C to remove moisture contained in the molding.

The coal gasification zone B heats the dried coal dried in the drying zone A to remove tar, volatile matter, etc. contained in the coal contained in the coal. At this time, the tar, volatile matter, and the like contained in the coal in the molded coal are volatilized at a temperature of about 300 to 800 ° C. Tar and volatile matter in coal are removed and CHn system is used. Since it can be used as fuel in combustion, exhaust gas generated in the coal gasification process can be supplied to the first cooling zone E1. When the flue gas generated in the coal gasification process is supplied to the first cooling zone E1, the CHn-based flue gas comes into contact with the reduced-temperature high-temperature reducing gas to decompose CHn, and the cooling efficiency of the reduced iron can be improved by the heat of decomposition. The C and H gases generated by the decomposition of the flue gas may be supplied to the reduction region D and used as a fuel necessary for reducing the briquettes.

When the oxygen concentration in the coal gasification zone (B) is high, coal and volatile matter in the coal are burned, so that the temperature of the coal is rapidly increased, which makes it difficult to control the process temperature. Do. Therefore, the oxygen concentration can be managed by using the exhaust gas generated in the preheating region C and the reduction region D. That is, the exhaust gas generated in the reduction region D is discharged to the preheating region C, mixed with the exhaust gas generated in the reduction region D, and supplied to the coal gasification region B. The exhaust gas generated in the preheating region (C) and the reduction region (D) is generated during the reduction of iron ore, and is characterized by a low oxygen concentration and a high temperature gas capable of raising the temperature of the briquette to about 800 ° C. At this time, when the temperature of the exhaust gas generated in the preheating region C and the reducing region D is excessively high, a part of the exhaust gas generated in the second cooling region E2 may be mixed and supplied to the coal gasification region B.

The preheating zone (C) and the reducing zone (D) are places where the reduction reaction of the briquettes occurs. At this time, the temperatures of the preheating region C and the reduction region D can be controlled to about 1000 to 1200 DEG C to secure the strength of the briquette. The preheating region C is a region where the temperature is raised to a temperature necessary for reducing the briquettes and the reduction of the briquettes proceeds partially. The reduction zone (D) is a section in which substantial heating of the briquette is performed and the reduction reaction of the briquette is continued. Here, the exhaust gas generated in the reduction region (D) is supplied to the preheating region (C) to heat the molded fuel. In the reducing region D, a burner is provided as described above, and the briquettes can be heated to a target temperature. The reduction region D is formed of a rotary furnace in a nearly closed form, and the inside atmosphere, particularly the oxygen concentration, can be easily controlled, thereby suppressing the melting of FeO or the like caused by reduction of the briquetted coal.

Reduced iron produced in the reduction zone D is discharged to the first cooling zone E1 and rotates along the inside of the cooling unit and is discharged to the outside through the second cooling zone E2. At this time, the outside air and the flue gas generated in the coal gasification region B are mixed and supplied to the first cooling region E1, thereby controlling the oxygen concentration in the first cooling region E1. That is, since the reduced iron has a temperature that is easily reoxidized in the first cooling region E1, it is necessary to control the oxygen concentration in the first cooling region E1 to be low. Therefore, the exhaust gas of the coal gasification zone B having a relatively low oxygen concentration and a low temperature can be supplied to the first cooling zone E1 to quench the reduced iron to about 400 ° C, thereby suppressing or preventing the reoxidation of the reduced iron.

The reduced iron cooled in the first cooling zone E1 is cooled to about 100 deg. C while moving along the second cooling zone E2, and then exits the cooling unit 530. [ In the second cooling zone E2, the external air is directly introduced to cool the reduced iron. In the second cooling zone E2, since the reduced iron is cooled to a temperature lower than the temperature at which the reoxidation occurs, reoxidization by oxygen can be suppressed or prevented even if air is cooled by flowing air from the outside. Such external air supply to the second cooling zone E2 can be the start of gas circulation in the burning apparatus.

In the embodiment of the present invention, the reduction efficiency of briquetting is increased at a plurality of steps required to induce the reduction reaction between coal (carbon component) and iron ore in the briquetting coal such as briquettes, and the melting of iron oxide (FeO) The temperature and the oxygen concentration in the baking furnace 510 can be partially controlled. At this time, the exhaust gas generated in a plurality of stages required to induce the reduction reaction of the briquettes can be circulated in the firing furnace 510 to control the temperature and oxygen concentration in each stage. In particular, the control of temperature and oxygen concentration in the cooling zone is very important in order to suppress the reoxidation of reduced reduced carbon, that is, reduced iron.

As described above, by applying a bogie moving type firing furnace, that is, an open firing furnace and a rotary firing furnace, to the firing apparatus for reducing the briquette, it is possible to improve the metallization rate of the reduced iron by partially controlling the temperature and the oxygen concentration at which the briquette is reduced. Further, by circulating the flue gas generated in the process of reducing the briquettes in the firing furnace, it is possible to secure the necessary energy in the process of reducing the briquette burning, thereby suppressing or preventing unnecessary energy consumption.

Although the present invention has been described in connection with certain exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. Therefore, the scope of the present invention should not be limited by the described embodiments, but should be defined by the appended claims and equivalents thereof.

100, 110, 120: hopper 200: crusher
300: mixer 400: molding machine
500: firing apparatus 510: first firing furnace
520: second firing furnace 530: cooling device

Claims (14)

A firing apparatus for producing reduced iron by heating a briquette,
A first firing furnace for heating the briquettes while moving the bogie charged with the briquettes along a linear movement path;
A second baking furnace connected to the other side of the first baking furnace and heating the briquettes discharged from the bogie while moving along an annular moving path;
And a cooling device connected to the second baking furnace and cooling the reduced iron reduced in the second baking furnace while moving the reduced iron along an annular movement path,
The first baking furnace is divided into a drying zone, a coal gasification zone and a preheating zone,
Wherein the cooling device is divided into a first cooling zone and a second cooling zone,
And a connection pipe communicating at least the coal gasification zone and the first cooling zone. delete delete The method according to claim 1,
Further comprising a connection pipe for communicating at least two areas of the drying zone, the coal gasification zone, the preheating zone and the second cooling zone. The method of claim 4,
And an inlet pipe for supplying outside air to the first cooling region and the second cooling region. The method of claim 5,
Wherein the inlet pipe of the first cooling zone is connected to a connection pipe connecting the coal gasification zone and the first cooling zone. delete The method of claim 5,
Wherein the preheating zone, the second cooling zone, and the coal gasification zone are in communication with each other. The method of claim 5,
Wherein the preheating zone and the drying zone are in communication with each other. A process for producing a blast furnace containing a carbonaceous material and an iron raw material;
A step of heat treating the briquettes and firing the briquettes to produce reduced iron; And
And cooling the reduced iron,
Wherein the flue gas generated in the coal gasification process for removing the volatile matter of the carbonaceous material contained in the briquettes in the process of producing the reduced iron is used as a cooling gas for the reduced iron. The method of claim 10,
And a step of preheating the briquettes after the coal gasification process. The exhaust gas generated in the process of preheating the briquettes and the exhaust gas generated in the process of cooling the reduced iron are mixed and supplied to the coal gasification process, A method for producing reduced iron. The method of claim 11,
Wherein the drying process is performed to remove moisture contained in the briquettes prior to the coal gasification process, and the drying process uses the exhaust gas generated in the process of preheating the briquettes as a heat source. The method of claim 12,
The process of cooling the reduced iron includes:
A first cooling step of cooling the reduced iron using the cooling gas as an exhaust gas generated in the coal gasification process,
And a second cooling step of cooling the reduced iron cooled in the first cooling step by using external air as a cooling gas. 14. The method of claim 13,
And a gas mixture of exhaust gas and external air generated in the coal gasification process in the second cooling process is used as a cooling gas.

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