JPH10316412A - Apparatus for producing iron carbide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the heating quantity in heating apparatuses for heating reactional gases fed to reactors to reduce the equipment and operating costs, by providing an oxygen gas feeder for adding oxygen gas to a reduced and carbonized gas after heating in a second heating apparatus between the second heating apparatus and the second reactor. SOLUTION: A powdered iron ore is supplied to the upper part of a fluidized bed type reactional furnace 19 of a first reactional operating part 10 and the partially reduced iron ore is continuously supplied from the lower part of the fluidized bed type reactional furnace 19 to a fluidized type reactional furnace 39 of a second reactional operating part 30 to carry out the residual reduction and carbonization. An iron carbide product is then taken out from a pipeline 52. An oxygen gas feeder 60 for adding oxygen gas to the reduced and carbonized gas after heating in a tubular heating furnace 37 is provided between the tubular heating furnace 37 and the second reactor 39. Thereby, the heating quantity in the heating apparatuses for heating the reactional gases is reduced. As a result, the grade of metallic materials used in the heating apparatuses can be reduced to lower lank.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the iron, the raw material for steel making, for example, a manufacturing apparatus for an iron carbide (Fe ₃ C) is suitable as steelmaking raw material used in the electric furnace or the like.

[0002]

BACKGROUND OF THE INVENTION Generally, the production of steel comprises the steps of converting iron ore to pig iron in a blast furnace, and then converting pig iron to steel in a flat furnace or a converter. Such traditional manufacturing methods require large amounts of energy, equipment scale, and cost.
Conventionally, for small-scale steelmaking, a method comprising a step of converting iron ore into a steelmaking furnace raw material (solid) by direct ironmaking and converting the steelmaking furnace raw material into molten steel by an electric furnace or the like has been adopted. In such direct iron production, there is a direct reduction method for converting iron ore to reduced iron. However, the reduced iron produced by this method has a strong reaction activity and reacts with oxygen in the atmosphere to generate heat, so that it is transported and stored. Requires a treatment such as sealing with an inert gas. For this reason, iron carbide, which has a low reaction activity, can be easily transported and stored, and contains a relatively high percentage of iron, has recently been used as a steelmaking raw material for electric furnaces and the like.

[0003] Further, the steel raw material containing iron carbide as a main component is not only easy to transport and store, but also the carbon combined with iron becomes a fuel source for iron making or a steel making furnace.
In a steelmaking furnace, there is also an advantage that it is a source of fine bubbles that promote the reaction. For these reasons, in recent years, raw materials for steelmaking and steelmaking mainly composed of iron carbide have attracted particular attention.

In a conventional method for producing such iron carbide, a powder of iron ore is charged into a fluidized bed reactor, and a reducing gas (hydrogen gas) and a carbonization gas (for example, methane gas, etc.) are used.
At a predetermined temperature with a mixed gas of iron oxide (hematite (Fe ₂ O ₃ ) and magnetite (F
e ₃ O _4), in which a reducing and carbonizing at wustite (FeO), etc.) a single operation ((refer to operation performed by introducing simultaneously one reactor to the reducing and carburizing gases). This type As the prior art, Japanese Patent Publication No. Hei 6-50198
There is one described in Japanese Patent Publication No.

The method of performing reduction and carbonization in a single operation has the advantage of system simplicity, but the reaction gas composition and reaction temperature are individually flexible so as to be optimal for each of the reduction reaction and carbonization reaction. , The reaction cannot proceed efficiently. Therefore, the present applicant has set the gas used in the first reaction operation to have the optimum composition only for the reduction reaction, and the gas used in the second reaction operation to have the optimum composition for the remaining reduction reaction and carbonization reaction. As such, `` after the first reaction operation to perform a part of the reduction reaction of the iron-containing raw material for iron making, the method for producing iron carbide characterized by proceeding a second reaction operation to perform the remaining reduction reaction and carbonization reaction and Filed a patent application for the invention relating to "manufacturing equipment" (Japanese Patent Application No. 8-30985).
issue). According to the present invention, various operations can be taken for each operation, which is impossible with a conventional apparatus for producing iron carbide in a single operation, and the process becomes flexible. However, there is an advantage that the flow rate can be greatly reduced, but there are some disadvantages as follows. That is, since the second reaction operation performed according to the following formula (1) is an endothermic reaction, the reaction gas heated by the heating device and supplied to the second reaction device is:
It must be heated above the reaction temperature.

3FeO _2/3 + CH ₄ → Fe ₃ C + 2H ₂ O (1) Since the reaction gas of the second reaction operation contains a carbon gas component such as methane (CH ₄ ), this carbon gas is heated. (For example, a heater tube type heating furnace shown in FIG. 6), the metal component (M) of the heater tube H reacts with the carbon (C) in the carbonized gas, and as shown in the following equation (2), Carbide (M _x C) may be generated.

C + xM → M _X C (2) When the formation of this metal carbide reaches supersaturation, carbon is separated as shown in the following equation (3), and at that time, the metal component of the heater tube is separated. .

M _X C → C + xM (3) Therefore, it is necessary to select the material of the heater tube so as to avoid such carburizing corrosion. That is, the reaction temperature of the second reaction operation is preferably about 630 ° C., but the temperature of the reaction gas supplied to the second reactor is heated to about 680 ° C. in order to compensate for the temperature decrease due to the endothermic reaction. In addition, since the temperature of the inner wall surface of the heater tube reaches about 730 to 800 ° C. in order to heat the gas to 680 ° C., the material of the heater tube is made of high-grade steel (for example, Ni-Cr-Mo steel) is used, and the equipment cost is high.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to reduce the amount of heating in a device for heating a reaction gas supplied to a reaction device and to reduce the amount of equipment. An object of the present invention is to provide an iron carbide manufacturing device capable of reducing costs and operating costs.

[0010]

In order to achieve the above object, the gist of the present invention is to add oxygen gas to a reaction gas heated by a heating device and burn hydrogen in the reaction gas with the oxygen gas. The generated heat raises the temperature of the reaction gas to compensate for a decrease in the reaction temperature caused by the endothermic reaction in the second reaction operation, thereby making it possible to reduce the amount of heating of the reaction gas in the heating device.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to an apparatus for producing iron carbide by reducing and carbonizing an iron-containing raw material, wherein a first gas is heated by a first heating device to partially reduce the iron-containing raw material. Subsequent to the reactor, in an iron carbide manufacturing device having a second reactor for performing the remaining reduction and carbonization by the reduction and carbonization gas heated by the second heating device, the second heating device and the second reactor The first invention is an iron carbide manufacturing device, characterized by having an oxygen gas supply device for adding oxygen gas to the reduction and carbonization gas after heating by the second heating device, In the invention of the first embodiment, the first reactor and the second reactor are each a production apparatus of iron carbide, which is a fluidized bed reactor, as the second invention, and in the second invention, the fluidized bed of the fluidized bed reactor is The third invention is an iron carbide manufacturing device divided into a plurality of chambers by a cutting plate, and in the third invention, a device for adding oxygen to a gas supplied to a specific chamber is provided. A fourth aspect of the present invention is an iron carbide manufacturing apparatus.

According to the present invention configured as described above,
In the first reactor, a part of the reduction reaction of the iron-containing raw material is performed, and in the second reactor, the remaining reduction reaction and carbonization reaction are performed, so that it is impossible with a conventional apparatus that manufactures iron carbide in a single operation. Since various measures can be taken, the reaction can proceed efficiently. Moreover, since there is an oxygen gas supply device between the second heating device and the second reaction device, the oxygen gas is added to the reaction gas (reducing gas and carbon gas) heated by the second heating device. Then, the hydrogen and oxygen in the reaction gas react with each other to obtain combustion heat as shown in the following equation (4).

H ₂ +1/2 O ₂ → H ₂ O + 57.6 kcal / g · mol (4) The constant pressure specific heat of H ₂ O at a temperature around 600 ° C. is 0.5 kcal.
/ Nm ³ · ° C., 0.5% by volume of oxygen gas is added to the reaction gas and reacted with hydrogen in the reaction gas.
H ₂ O in the reaction gas increases by 1% by volume, and the temperature T of the reaction gas increases by 51.4 ° C. as shown in the following equation.

T = 57.6 × 10 ³ /(22.4×0.5)/100=51.4 (° C./1% H ₂ O) In this manner, the temperature of the reaction gas rises. It is not necessary to heat the reaction gas excessively in the two-heating device, and it becomes possible to lower the grade of the metal component of the heater tube. Further, the amount of gas used for heating can be significantly reduced.

[0015]

Embodiments of the present invention will be described below. As shown in FIG. 1, the apparatus of the present embodiment uses
It comprises a first reaction operation section 10 for partially reducing iron ore mainly containing hematite, and a second reaction operation section 30 for performing the remaining reduction reaction and carbonization reaction. The flow of the reaction gas in the first reaction operation part 10 is
2, compressor 13, pipe 14, heat exchanger 15, pipe 16,
Tubular heating furnace (first heating device) 17, pipe 18, fluidized bed reactor (first reactor) 19, pipe 20, heat exchanger 1
5, the pipe 21, the scrubber 22, and the pipe 23 form a loop. That is, the reaction gas flows through the pipe 12, the compressor 13, the pipe 14, the heat exchanger 15, the pipe 16, the tubular heating furnace 17, and the pipe 18 in order at the bottom gas inlet of the fluidized bed reactor 19. The pipe 20, the heat exchanger 15, the pipe 21, the scrubber 2 are supplied from the top outlet of the fluidized bed reactor 19.
2. A loop is formed in which the reaction gas circulates sequentially through the pipeline 23, the pipeline 11, and the pipeline 12.

Further, a gas having a predetermined composition is supplied to the circulation path from a pipe 24 connected to a connection section between the pipes 11 and 12, and a pipe connected to a connection section between the pipe 11 and the pipe 23. A predetermined amount of gas is discharged from the passage 25. By adjusting the make-up gas and the discharge gas, the composition of the reaction gas flowing into the fluidized bed reactor 19 is made constant, and A change in gas composition and a decrease in reaction rate can be prevented.

Since the flow of the reaction gas in the second reaction operation part 30 is the same as that in the first reaction operation part, the common parts are numbered by adding 20 to each number of the first reaction operation part 10. Description is omitted.

In the iron carbide manufacturing apparatus configured as described above, when powdered iron ore is supplied to the upper part of the fluidized bed reactor 19 of the first reaction operation section 10 through the pipe 50, The reduced iron ore is continuously supplied from the lower part of the fluidized bed reactor 19 to the fluidized bed reactor 39 of the second reaction operation section 30 through the pipe 51, and the fluidized bed reactor 39 After performing the remaining reduction and carbonization, the iron carbide product is continuously taken out through the pipeline 52. Regarding the composition of the reaction gas used in the above reaction, since the first reaction operation only needs to consider the reduction reaction, the first reaction operation is performed using a reducing gas mainly composed of hydrogen, and the second reaction operation considers the reduction reaction and the carbonization reaction. Must be performed with a mixed gas of hydrogen and methane. Further, the preferable reaction temperature of the fluidized bed reactor 39 is about 630 ° C., and the reaction gas supplied to the fluidized bed reactor 39 is heated to about 580 ° C. in the heat exchanger 35, After being heated to about 630 ° C. in the furnace 37, the oxygen gas supply device 60 installed between the tubular heating furnace 37 and the fluidized-bed reactor 39.
The combustion heat is generated by the oxygen gas supplied from the pipe 38 to the pipe 38 as shown in the above equation ((4)).
, The temperature of the reaction gas supplied to the fluidized bed reactor 39 can be increased. In this case, since 0.5% by volume of oxygen gas was added from the oxygen gas supply device 60 to the line 38, H ₂ in the circulation gas in the circulation loop of the second reaction operation was added.
O 2 increased by 1% by volume and the temperature of the reaction gas increased by about 50 ° C. to about 680 ° C. As described above, by burning the hydrogen in the reaction gas with the oxygen supplied from the oxygen gas supply device, the temperature of the reaction gas supplied to the fluidized bed reactor 39 (second reaction device) can be raised by about 50 ° C. Therefore, the heating amount of the tubular heating furnace 37 (second heating device) can be reduced by half. As a result, the material grade of the heater tube can be reduced, and the amount of gas used for heating in the tubular heating furnace 37 can be significantly reduced.

By the way, the scrubber 42 has a hollow main body 4.
6. A pipe 47 for injecting water into the gas and a pipe 48 for discharging the water in the main body 46. The gas discharged from the reaction furnace 39 is cooled, and H ₂ O (water vapor) in the gas is cooled. Is condensed and removed. Most of the H ₂ O generated as a result of the reduction reaction in the reactor 39 is removed in the scrubber 42, and the H ₂ O in the gas discharged from the scrubber 42 to the pipe 43 becomes about 1% by volume. Since H ₂ O as a result generating combustion in the H ₂ O content is added, H ₂ O in the gas circulating in the circulation loop is about 2 volume%.

On the other hand, the actual reaction of the second reaction operation part is
It proceeds according to the following equations (5) and (6).

CH ₄ + H ₂ O → 3H ₂ + CO (5) 3Fe + CO + H ₂ → Fe ₃ C + H ₂ O (6) As is apparent from the equation (6), the circulating gas contains a large amount of H ₂ O. , Iron carbide (Fe ₃ C) is less likely to be generated. Therefore, in order to promote the formation of iron carbide smoothly, H ₂ O in the circulating gas is preferably to below a certain level, which was determined by experiment that value, H ₂ O
/ H ₂ ≦ 0.2 was found to be preferable. Since H _{2 in} the circulating gas of this embodiment is about 35%, the upper limit of H ₂ O in the circulating gas needs to be about 7% in order to generate iron carbide smoothly. I understand. However, in consideration of variations in operating conditions and the like, it is preferable that H ₂ O in the circulating gas is lower, and it is considered that about 6% by volume is the upper limit of H ₂ O in the circulating gas. As described above, in the conventional apparatus having no oxygen gas supply device, since the circulating gas constantly contains 1% by volume of H ₂ O, the allowable amount of H ₂ O in the circulating gas is: The deduction is 5% by volume. On the other hand, in the present embodiment, since the gas circulating in the circulation loop contains 2% by volume of H ₂ O, it is allowed to circulate in the gas as H ₂ O to produce a result of the reduction reaction H _The amount of ₂ O is 4% by volume.
Thus, the amount of H ₂ O allowed in the circulating gas is 1 /
In order to avoid a decrease in the reaction rate due to a decrease of 5 (20%), the total amount of the circulating gas may be increased, specifically, it may be increased by a factor of 5/4, about 25%.

FIG. 2 shows the relationship between the reaction temperature (° C.) and the total amount of gas used (the total amount of the circulating gas and the gas used in the tubular heating furnace). In the case where oxygen gas was not added, the line B indicates the case where oxygen gas was added to the outlet gas of the tubular heating furnace 37 at 0.5% by volume. As is clear from FIG. 2, by adding oxygen gas to the outlet gas of the tubular heating furnace 37, the amount of gas used for heating can be significantly reduced, and as a result, the total gas consumption can be reduced. Can be reduced. FIG. 3 shows the relationship between the amount of H ₂ O in the circulating gas and the total amount of gas used.
It can be seen that the total amount of gas used decreases as the amount of H ₂ O generated by adding oxygen gas to the outlet gas and burning the hydrogen gas increases (the amount of heat generated by combustion increases).

FIG. 4 is a view showing an example in which a fluidized bed of a fluidized bed reactor is divided into multiple chambers by a partition plate. In FIG. 4, a dispersion plate 71 having a large number of small holes is provided at the bottom of a fluidized bed furnace 70, and a supply gas duct 72 at the bottom is provided.
The reaction gas supplied into the furnace from
1 and reaches the fluidized bed 74. The fluidized bed 74 is divided into three chambers (74a, 74a) by two partition plates 75.
b, 74c). 76 is an exhaust gas duct,
Reference numeral 77 denotes an input pipe for the raw material of the granular material, 78 denotes an exhaust pipe for the product (iron carbide), and 79 denotes an input pipe for inputting the fine powder in the furnace gas collected by a cyclone (not shown). As described above, when the fluidized bed is divided into a plurality of sections by the partition plate, the residence time of the raw material in the fluidized bed becomes longer, and the purity of the obtained product is improved.

FIG. 5 shows that each of the chambers (74a, 74b, 74c) divided by a partition plate is provided with a separate gas supply pipe (38a, 38b, 38c), and oxygen gas is supplied to a specific pipe 38a. The supply device 60 is connected. That is, the fluidized bed 74 is thus formed by the partition plate.
Is divided into a plurality of chambers, the reaction amount in each chamber is slightly different, so that the temperature required for the gas supplied to each chamber is also different. Therefore, instead of adding oxygen gas to the total amount of gas supplied to the fluidized bed, oxygen gas is added to gas supplied to a specific chamber. The gas distributors indicated by reference numerals 80a, 80b, and 80c in the figure are different from the distribution plate 71 shown in FIG. 4 in that pipes having a large number of gas injection holes are arranged in a lattice. . The oxygen gas added to the circulating gas does not need to be pure, but is generally obtained industrially, and may contain some impurities (N ₂ or Ar gas). is there. Also,
Even if oxygen gas is added to the line 18 of the first reaction operation part,
Naturally, the load on the tubular heating furnace can be reduced in the same manner as described above.

[0025]

Since the present invention is configured as described above, the following effects can be obtained. According to the first aspect of the present invention, since the heating amount of the heating device for heating the reaction gas is reduced, it is possible to reduce the grade of the metal material used for the heating device, thereby reducing the equipment cost and operating. Cost (gas usage) can be reduced. In this case, if the temperature of the reaction gas heated by the heating device is not changed, an effect that productivity can be improved by increasing the reaction temperature can be expected.

According to the second aspect of the present invention, since the supply of the raw material and the discharge of the product can be performed continuously and the reaction is performed uniformly, there is an effect that the variation in the quality of the obtained product is reduced.

According to the third aspect of the present invention, since the residence time of the raw material in the furnace is lengthened, there is an effect that the purity of the obtained product is improved.

According to the fourth aspect of the invention, when the fluidized bed of the fluidized bed reactor is divided into a plurality of chambers, the temperature of the gas supplied to a specific chamber can be increased. There is.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of an iron carbide manufacturing apparatus of the present invention.

FIG. 2 is a diagram showing the relationship between the reaction temperature and the total gas usage,
Line A shows the case where oxygen gas was not added to the circulating gas, and line B shows the case where oxygen gas was added to the outlet gas of the tubular heating furnace at 0.5% by volume (H ₂ O in the circulating gas was 1%). It is a figure which shows the case (volume% increase).

FIG. 3 is a diagram showing the relationship between the amount of H ₂ O (vol%) generated by adding oxygen gas to a circulating gas and reacting with hydrogen gas, and the total amount of gas used.

FIG. 4 is a sectional view of an example of a multi-chamber split type fluidized bed furnace.

FIG. 5 is a sectional view of another example of a multi-chamber split type fluidized bed furnace.

FIG. 6 is a sectional view showing the inside of a tubular heating furnace.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... 1st reaction operation part 17 ... Tubular heating furnace (1st heating apparatus) 19 ... Fluidized bed type reaction furnace (1st reaction apparatus) 30 ... 2nd reaction operation part 37 ... Tubular heating furnace (2nd heating apparatus) 39: fluidized bed reactor (second reactor) 60: oxygen gas supply device

Claims (4)

[Claims] An apparatus for producing iron carbide by reducing and carbonizing an iron-containing raw material, comprising: a first reactor for partially reducing an iron-containing raw material by a reducing gas heated by a first heating device; In an iron carbide production device having a second reactor for performing the remaining reduction and carbonization by the reduction and carbonization gas heated by the heating device, the second heating device heats the second reactor between the second heater and the second reactor. An apparatus for producing iron carbide, comprising an oxygen gas supply device for adding oxygen gas to the reduced and carbonized gas after the reduction. 2. The iron carbide manufacturing apparatus according to claim 1, wherein each of the first reactor and the second reactor is a fluidized bed reactor. 3. The iron carbide manufacturing apparatus according to claim 2, wherein the fluidized bed of the fluidized bed reactor is divided into a plurality of chambers by a partition plate. 4. An apparatus for adding oxygen to a gas supplied to a specific chamber is provided.
An iron carbide manufacturing apparatus as described above.