A FLUIDIZED BED REACTOR FOR PREVENTING THE FINE IRON

Europäisches Patentamt
(19)
European Patent Office
*EP001177322B1*
Office européen des brevets
(11)
EP 1 177 322 B1
EUROPEAN PATENT SPECIFICATION
(12)
(45) Date of publication and mention
(51) Int Cl.7:
of the grant of the patent:
09.03.2005 Bulletin 2005/10
C21B 3/00
(86) International application number:
PCT/KR2000/001495
(21) Application number: 00986025.5
(87) International publication number:
(22) Date of filing: 20.12.2000
WO 2001/046478 (28.06.2001 Gazette 2001/26)
(54) A FLUIDIZED BED REACTOR FOR PREVENTING THE FINE IRON ORE FROM STICKING
THEREIN AND METHOD THEREFOR
FLUIDATBETTREAKTOR ZUR VERHINDERUNG DES ANHAFTENS DES FEINEISENERZES UND
VERFAHREN
REACTEUR A LIT FLUIDISE EMPECHANT L’AGGLUTINATION DU MINERAIS FIN DE FER ET
PROCEDE ASSOCIE
(84) Designated Contracting States:
• KIM, Hang-Goo
Pohang-city 790-330 (KR)
• KANG, Heung-Won
Pohang-city 790-330 (KR)
• HAUZENBERGER, Franz, Voest-Alpine
A-4031 Linz (AT)
AT DE GB IT LU SE
(30) Priority: 20.12.1999 KR 9959509
(43) Date of publication of application:
06.02.2002 Bulletin 2002/06
(74) Representative:
(73) Proprietors:
• POHANG IRON & STEEL CO., LTD
Kyungsangbuk-do 790-300 (KR)
• RESEARCH INSTITUTE OF INDUSTRIAL
SCIENCE & TECHNOLOGY
Pohang-city, Kyungsangbuk-do 790-330 (KR)
Kaiser, Jürgen, Dr.rer.nat.Dipl.-Chem.
Winter, Brandl, Fürniss, Hübner,
Röss, Kaiser, Polte
Partnerschaft
Patent- und Rechtsanwaltskanzlei
Alois-Steinecker-Strasse 22
85354 Freising (DE)
(72) Inventors:
EP 1 177 322 B1
• CHOI, Nag-Joon
Pohang-city 790-330 (KR)
• JEONG, Sun-Kwang
Pohang-city 790-330 (KR)
(56) References cited:
WO-A1-96/21045
Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give
notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in
a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art.
99(1) European Patent Convention).
Printed by Jouve, 75001 PARIS (FR)
EP 1 177 322 B1
Description
BACKGROUND OF THE INVENTION
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(a) Field of the Invention
[0001] The present invention relates to smelting reduction process and, more particularly, to a smelting reduction
apparatus which separates exhaust gas, which is exhausted from a melter-gasifier or a fluidized bed reactor, into dusts
and reducing gas to supply them to a corresponding fluidized bed reactor respectively.
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(b) Description of the Related Art
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[0002] Generally, a blast furnace has been extensively used to make iron through reducing and melting iron ores.
However, the blast furnace involves a drawback that the charging materials should be pre-treated to bear agglomerated
forms such as sintered iron ores and cokes.
[0003] In order to solve such a problem, a smelting and reduction process has been developed for the direct use of
fine iron ores and coal without pre-treatment.
[0004] The smelting reduction process is composed of a preliminary reduction process and a final reduction process.
In the preliminary reduction process, the charged fine iron ores are pre-heated and then preliminarily reduced. in the
final reduction process, a sponge iron which is reduced in the preliminary reduction process is finally reduced and
melted in the presence of high pressure oxygen and coal to thereby form a molten iron.
[0005] The fluidized bed reduction reactor (hereinafter, referred to "fluidized bed reactor") is used as an equipment
for the preliminary reduction process, and a melter-gasifier is used as an equipment for the final reduction process.
[0006] The preliminary reduction process is typically divided into a moving bed type and a fluidized bed type according
to a contact state between raw iron ores and reducing gas. It is efficient to apply the fluidized bed type preliminary
reduction process rather than the moving bed type if the charged iron ore has a small particle size and a wide particle
size distribution.
[0007] Korean Patent No. 117065 discloses an apparatus for such a fluidized bed type preliminary reduction process.
According to this patent, a device for uniformly reducing a fine iron ore having a wide particle size distribution in a
fluidized bed reactor is proposed. In order to achieve such a uniform reducing of the fine iron ore, the patent provides
a three-stage type fluidized reactor which is designed in a conical shape having a wide upper part and a narrow lower
part, wherein the iron ore is reduced through three stages of pre-heating, pre-reducing and final preliminary reducing.
This patent also proposes a cyclone for collecting fine iron ore, which is discharged, from an upper part of the respective
fluidized bed reactors by scattering to supply to a bottom part of the respective fluidized bed reactors.
[0008] According to this patent designed as above, the fine iron ore having the wide particle size distribution may
be efficiently reduced while maintaining stable fluidized state.
[0009] This patent has, however, a disadvantage that a gas distributor of the fluidized bed reactors may be clogged
by dust contained in the reducing gas. That is, a large amount of dusts is included in exhaust gas, which is discharged
from the melter-gasifier and supplied to the fluidized bed reactors. If the dusts are supplied to the gas distributor of a
final reduction furnace, the dust becomes stuck to nozzles, which are mounted in the gas distributor, and if the sticking
phenomenon is accumulated, the gas distributor itself becomes clogged.
[0010] If the gas distributor is clogged as above, it becomes impossible to maintain a uniform flow of the reducing
gas in the fluidized bed reactors, and more severely, operations should be stopped.
SUMMARY OF THE INVENTION
[0011] Therefore, the present invention is derived to resolve the above disadvantages and problems of the related
art and has an object to provide a smelting and reduction apparatus which can separate exhaust gas, which is exhausted
from a melter-gasifier or a fluidized bed reactor, into dusts and reducing gas to supply them to each fluidized bed
reactor respectively.
[0012] It is another object of the present invention to provide a method for manufacturing molten pig iron by a smelting
and reduction process, which can prevent sticking of particles of fine iron ores and clogging of a gas distributor by
coating separated dusts on a surface of the particles of the fine iron ores which is flowing in the fluidized bed reactors.
[0013] This and other objects may be achieved by the present invention, which is described in detail hereinafter.
[0014] According to one aspect of the present invention, a smelting and reduction apparatus includes a three-stage
type fluidized reactor, a melter-gasifier for manufacturing molten pig iron by finally reducing fine iron ores of which
reaction is finished in a final fluidized reactor, and a dust separating device, which performs separation of exhausted
gas from the melter-gasifier into dusts and reducing gas so as to supply the separated reducing gas to a lower part of
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the final fluidized bed reactor, dusts having a larger particle sizes in the separated dusts to the melter-gasifier again,
and fine dusts having a smaller particle sizes in the separated dusts to an upper part of a gas distributor of the final
fluidized bed reactor.
[0015] The three-stage type fluidized bed reactor of the present invention includes a) an ore charging duct mounted
on a side of respective fluidized bed reactors for charging fine iron ores, b) a gas supply duct mounted at a lower part
of the respective fluidized bed reactors, c) an ore discharge duct mounted on a side wall of the respective fluidized
bed reactors for discharging fine iron ores which are charged into the respective fluidized bed reactors and reactions
thereof are finished, d) a gas distributor mounted in the respective fluidized bed reactors for uniformly dispersing reducing gas into the respective fluidized bed reactors, and e) a cyclone for separating fine iron ore particles from the
reducing gas, which is discharged from the upper parts of the respective fluidized bed reactors, to supply the reducing
gas to next reactor or discharge outside and recycle the fine iron ore particles to the lower parts of the respective
fluidized bed reactors.
[0016] In the present invention, each fludized bed reactor is manufactured in a dual-stage cylindrical shape of which
a diameter of a lower part is small and a diameter of an upper part is large so that lower and the upper parts are
connected to each other slantingly. In the dual-stage cylindrical fluidized bed reactors, the diameter of the upper cylindrical part is larger than that of the lower cylindrical part by 1.5~2.0 times, and the inclination of the connection
between the upper and lower cylindrical parts is 20~30° with relation to a central axis of the fluidized bed reactors. A
whole height of the fluidized bed reactors is larger than a diameter of the lower cylindrical part by 10~20 times.
[0017] In the present invention, the dust separation device is formed of at least two or more cyclones and at least
one or more dust storage bins. A first cyclone of the cyclones is connected to the upper part and the lower part of the
melter-gasifier and an upper part of a second cyclone. The second cyclone is connected to the lower part of the final
fluidized bed reactor and an upper part of the dust storage bin and the dust storage bin is connected to an upper part
of the gas distributor of the final fluidized bed reactor.
[0018] In the dust separation device, the second cyclone and the dust storage bin is connected by a dust supply
duct which is mounted with a two-way valve, wherein the dust supply duct branched by the two-way valve is connected
to a dust supply duct which connects the first cyclone and the melter-gasifier.
[0019] The dust storage bin part is formed of three dust storage bins respectively connected to one another via the
dust supply ducts. The dust supply duct which is positioned at a lower part of a first dust storage bin is mounted with
a nitrogen gas injection device, so that dusts stored in the first dust storage bin can be pneumatically transported to a
second dust storage bin with high pressure nitrogen gas. A dust supply duct which is positioned at a lower part of a
third dust storage bin is also mounted with a nitrogen gas injection device, so that the dusts stored in the third dust
storage bin can be introduced into the final reactor with high pressure nitrogen gas.
[0020] On the other hand, a dust supply duct connecting the lower part of the third dust storage bin to the nitrogen
gas injection device is mounted with a dust introducing feeder for controlling the amount of dust supply to the final
reactor. Further, each of the dust supply ducts is mounted with a control valve for controlling a supply of the dusts
conveyed to the dust supply ducts.
[0021] The molten pig iron is manufactured from the fine iron ores by using the smelting reduction apparatus hereinabove.
[0022] The process for manufacturing the molten pig iron by using the smelting reduction apparatus of the present
invention is characterized in that the exhaust gas discharged from the melter-gasifier is separated into reducing gas
and dusts to be supplied to the final fluidized bed reactor.
[0023] Even though the separated reducing gas is directly supplied to the lower part of the final fluidized bed reactor,
the dusts are separated again such that the fine dusts having a smaller particle size is blown into the upper part of the
gas distributor of the final fluidized bed reactor by high pressure nitrogen.
[0024] As the fine dusts are blown into the fluidized bed reactor, the fine dusts are coated on surfaces of the fine
iron ores, so that the sticking between the fine iron ores and the gas distributor may be prevented.
[0025] The pressure of the nitrogen for the injection of dust particles is controlled higher than an internal pressure
of the final fluidizing bed reactor by 2~3 times.
[0026] A velocity of the reducing gas in the respective fluidizing bed reactors is preferably controlled 1.2~1.5 times
of a minimum fluidizing velocity of the fine iron ores residing in the fludizing bed reactors.
[0027] If the molten pig iron is manufactured by the process described hereinabove, the sticking between the fine
iron ores and the gas distributor may be prevented, thereby effectively preventing operation obstacles of the smelting
reduction process.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] A more complete appreciation of the invention, and many of the attendant advantages thereof, will be readily
apparent as the same becomes better understood by reference to the following detailed description when considered
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in conjunction with the accompanying drawing, in which like reference symbols indicate the same or the similar components, wherein:
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Fig. 1 is a structural view of a smelting reduction apparatus including a three-stage type fluidized bed reactor
according to a preferred embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
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[0029] Preferred embodiments of this invention will be explained with reference to the accompanying drawing.
[0030] Fig. 1 illustrates a structural view of a smelting reduction apparatus including three-stage type fluidized bed
reactors.
[0031] As shown in Fig. 1, the smelting reduction apparatus includes a three-stage type fluidized bed reactor and a
melter-gasifier 40.
[0032] The three-stage type fluidized bed reactors include a pre-heating furnace 10, a pre-reducing furnace 20, and
a final reducing furnace 30.
[0033] The pre-heating furnace 10 is mounted with an ore charging duct 1 on a side wall for charging fine iron ores
which fall down from a charging bin 5, a gas supply duct 28 at a lower part for supplying reducing gas which is discharged
from the pre-reducing furnace 20, and a first cyclone 15 at an upper part. The first cyclone 15 collects fine particles of
ores which are included in the exhaust gas discharged via a gas discharging duct 13 and re-supplies the fine ore
particles to the lower part of the pre-heating furnace 10. The exhaust gas from which the fine ore particles are removed
is released outside via a discharge duct 16, which is mounted at an upper part of the cyclone 15.
[0034] The pre-reducing furnace 20 is mounted with an ore discharging duct 11 on a side wall for supplying the fine
iron ores which are preheated in the pre-heating furnace 10, a gas supply duct 38 at a lower part for supply reducing
gas which is discharged from the final reducing furnace 30, and a second cyclone 25 at an upper part. The second
cyclone 25 collects fine particles of ores which are included in the exhaust gas discharged via a gas discharging duct
23 and re-supplies the fine ore particles to a lower part of the pre-reducing furnace 20. The exhaust gas from which
the fine ore particles are removed is supplied to the lower part of the pre-heating furnace 10 via a gas supply duct 28
which is mounted at an upper part of the cyclone 25.
[0035] The final reducing furnace 30 is mounted with an ore discharging duct 21 on a side wall for supplying the fine
iron ores which are pre-reduced in the pre-reducing furnace 20, a gas supply duct 58 at a lower part for supply reducing
gas which is discharged from the melter-gasifier 40, and a third cyclone 35 at an upper part. The third cyclone 35
collects fine particles of ores which are included in the exhaust gas discharged via a gas discharging duct 33 and resupplies the fine ore particles to a lower part of the final reducing furnace 30. The exhaust gas from which the fine ore
particles are removed is supplied to the lower part of the pre-reducing furnace 20 via a gas supply duct 38 which is
mounted at an upper part of the cyclone 35.
[0036] As for the shape of the respective fluidized bed reactors as described above, the pre-heating furnace 10, the
pre-reducing reactor 20 and the final reducing reactor 30 has a small diameter in the lower parts 10a, 20a, and 30a,
a large diameter in the upper parts 10b, 20b, and 30b, and the slantingly formed cylindrical connection parts 10c, 20c,
and 30c. Therefore, the whole shape of the respective fluidized bed reactors is formed in the dual-stage cylinder having
the narrow lower parts and the wide upper parts.
[0037] The diameter of the upper parts 10b, 20b and 30b of the respective fluidized bed reactors is formed in the
range of 1.5~2.0 times of the diameter of the lower parts 10a, 20a and 30a, such that the velocity of the gas in the
upper parts of the respective fluidized bed reactors is decreased for preventing the fine iron ores from being discharged
as they are.
[0038] The whole height of the respective fluidized bed reactors is preferably formed 10~20 times of the diameter
of the lower parts 10a, 20a and 30a. If the respective fluidized bed reactors are formed in the elongated dual-stage
cylindrical shape, a space in which the fine iron ores flow is sufficiently assured and the fine iron ores are prevented
from being discharged as they are. Further, height of the cylindrical lower parts 10a, 20a and 30a is preferably formed
in 1.0~1.5 times of height of the cylindrical upper parts 10b. 20b and 30b, and the inclination of the connecting parts
10c, 20c and 30c is preferably formed inclined by 20~30° with relation to the central axes of the respective fluidized
bed reactors.
[0039] The fine iron ores which are preliminary reduced in the final reducing furnace 30 of the three-stage type
fluidized bed reactors as above, are supplied to the upper part of the melter-gasifier 40 which will be described hereinafter via an ore discharging duct 31. The exhaust gas, which is discharged from the melter-gasifier 40, is, however,
not directly supplied to the final reducing furnace 30 but via the dust separation device, which will be described hereinafter.
[0040] The dust separation device according to the present invention is mounted between the melter-gasifier 40 and
the final reducing furnace 30 and includes two cyclones and three dust storage bins which are disposed in series.
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[0041] Now, the dust separation device will be described in more detail.
[0042] First, a fourth cyclone 45, which is a first element of the dust separation device, is connected to the melter
gasifier 40, through an exhaust gas discharging duct 43 and a first dust supply duct 46. The fourth cyclone 45 is supplied
with high temperature exhaust gas from the melter-gasifier 40 via the exhaust gas discharging duct 43 and primarily
separate dusts which are included in the exhaust gas to collect. The dusts collected by the fourth cyclone 45 are
supplied to the melter-gasifier 40 via the first dust supply duct 46. Reducing gas from which the dusts are primarily
removed in the fourth cyclone 45 is supplied to a fifth cyclone 50 which will be described hereinafter via an exhaust
gas discharging duct 47 which is mounted at an upper part of the fourth cyclone 45.
[0043] The fifth cyclone 50 separates and collects dusts of an ultra fine particle shape which are included in the
reducing gas which is supplied from the fourth cyclone 45 but not separated by the fourth cyclone 45. The ultra fine
dusts collected by the fifth cyclone 50 are supplied to a first dust storage bin 60 via a second dust supply duct 51 which
is connected to a lower part of the fifth cyclone 50, wherein the second dust supply duct 51 is mounted with a two-way
valve 52 so that the dusts collected in the fifth cyclone 50 are partially re-supplied to the melter-gasifier 40 via a third
dust supply duct 57 as necessary. The third dust supply duct 57 may be directly connected to the melter-gasifier 40
and is more preferably connected to the first dust supply duct 46.
[0044] The fifth cyclone 50 is connected to a reducing gas discharge duct 58 at an upper part to supply the reducing
gas from which the dusts are removed to the final reducing furnace 30.
[0045] The first dust storage bin 60 is mounted with a first nitrogen injection device N1 at a lower part for conveying
the stored ultra fine dusts to a second dust storage bin 70. The first dust storage bin 60 is connected to the dust storage
bin 70 via a dust conveying duct 61.
[0046] The second dust storage bin 70 is connected to a. third dust storage bin 80 via a fourth dust supply duct 71,
so that the ultra fine dusts collected in the second dust storage bin 70 are supplied to the third dust storage bin 80 via
the fourth dust supply duct 71.
[0047] A lower part of the third dust storage bin 80 is connected to an upper part of a gas distributor 32 of the final
reducing furnace 30 via a fifth dust supply duct 81. The fifth dust supply duct 81 is mounted with a dust charging feeder
82 at an upper part for controlling the amount of dusts which are supplied to the final reducing furnace 30. The dust
charging feeder 82 is mounted with a second nitrogen-injection device N2 at a lower part for introducing the ultra fine
dusts to the final reducing furnace 30 with high pressure. Accordingly, the ultra fine dusts which are injected into the
upper part of the gas distributor 32 of the final reducing furnace 30 with the high pressure by the second nitrogeninjection device N2 are coated on surfaces of the fine iron ores in the final reducing furnace 30.
[0048] The dust separation device of the present invention as described above, is mounted with control valves 53,
63, 73, and 83 on the respective dust supply ducts for stopping the flow of the dusts and gas in case of operating or
repairing the device if it is necessary.
[0049] Now the method for manufacturing the molten pig iron by melting the fine iron ores of a wide particle size
distribution by using the smelting reduction apparatus of the present invention will be described in more detail.
[0050] First, the fine iron ores fallen down from a charging bin 5 are supplied to a side of the pre-heating furnace 10
via an ore charging duct 1, the iron ores of fine particles which are collected in the first cyclone 15 are supplied to a
side of the pre-heating furnace 10 via a first circulation duct 17, and the high temperature reducing gas which is discharged from the pre-reducing furnace 20 is supplied to a lower part of the pre-heating furnace 10 via the gas supply
duct 28. The fine iron ores and the iron ores of fine particles. which are supplied to the pre-heating furnace 10, are
preheated by the reducing gas in the pre-heating furnace 10, forming a bubbling fluidized bed.
[0051] The pre-reducing furnace 20 is supplied with the fine iron ores preheated by the pre-heating furnace 10 via
an ore charging duct 11 to a side, as well as the iron ores of fine particles, which are collected in the second cyclone
25, via a second circulation duct 27 to a side. Further the pre-reducing furnace 20 is supplied with the high temperature
reducing gas discharged from the final reducing furnace 30 to its lower part via a gas supply duct 38. The fine iron ores
and the iron ores of fine particles, which are supplied to the pre-reducing furnace 20, are pre-reduced by the reducing
gas in the pre-reducing furnace 20, forming a bubbling fluidized bed.
[0052] The final reducing furnace 30 is supplied with the fine iron ores pre-reduced by the pre-reducing furnace 20
via an ore charging duct 21 to a side, as well as the iron ores of fine particles, which are collected in the third cyclone
35, via a third circulation duct 37 to a side. Further the final reducing furnace 30 is supplied with the high temperature
reducing gas discharged from the fourth cyclone 50 to its lower part via a gas supply duct 58. The fine iron ores and
the iron ores of fine particles which are supplied to the final reducing furnace 30 are finally preliminary reduced by the
reducing gas in the final reducing furnace 30, forming a bubbling fluidized bed.
[0053] As above, fine particle sponge iron, which is sequentially preliminary reduced while passing through the threestage type fluidized bed reactor, are charged into the upper part of the melter-gasifier 40 via the ore discharge duct
31. The melter-gasifier 40 is supplied with coal and high pressure oxygen in addition to the sponge iron which is supplied
from the final reducing reactor 40 so as to finally reduce the sponge iron and melt, thereby producing the molten pig iron.
[0054] The melter-gasifier 40 generates a lot of exhaust gas of high temperature in the process of melting the sponge
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iron.
[0055] The exhaust gas contains ultra fine dusts which contains a lot of carbon and carbonized gas generated in the
process of the burning of the charged coal. The dusts contained carbon and carbonized gas are sequentially separated
by the dust separation device of the present invention. Now; the process for separating the exhaust gas will be described
in more detail.
[0056] The exhaust gas, which is discharged from the melter-gasifier 40, is supplied to the fourth cyclone 45 via the
discharge duct 43. The exhaust gas supplied to the cyclone is separated into dusts in the particle state and carbonized
gas in the gas state by a strong centrifugal force, wherein the separated dusts are fallen down to a lower part in the
cyclone and the carbonized gas is gathered to an upper part in the cyclone. The separated dusts collected to the lower
part are re-supplied to the melter-gasifier 40 via the first dust supply duct 46, while the separated carbonized gas is
discharged to the fifth cyclone 50, containing the ultra fine dusts which are not separated.
[0057] The fifth cyclone 50 secondarily collects the ultra fine dusts included in the supplied carbonized gas. The
carbonized gas from which the ultra fine dusts are separated is supplied to the final reducing furnace 30 to be used
as the reducing gas. The ultra fine dusts collected in fifth cyclone 50 are supplied to the melter-gasifier 40 or the first
dust storage bin 60.
[0058] The dusts discharged to the first dust storage bin 60 are conveyed to the second dust storage bin 70 by the
first nitrogen injection device N1 and continuously supplied to the third dust storage bin 80.
[0059] The dusts stored in the third dust storage bin 80 are injected to the upper part of the gas distributor 32 of the
final reducing furnace 30 by the second nitrogen injection device N2 and coat the fine iron ore particles which are in
bubbling fluidization state in the final reducing furnace 30.
[0060] At this time, the pressure of the nitrogen supplied by the first and second nitrogen injection devices N1 and
N2 is higher than the pressure in the furnace by 2~3 times. The dusts are smoothly conveyed and stabled injected in
the final reducing furnace 30 by the high pressure of the nitrogen.
[0061] An amount of the dusts which are introduced into the final reducing furnace 30 is preferably controlled to be
0.5~1.0wt% with relation to an amount of raw iron ores which are charged into the pre-heating furnace 10. If the amount
of the dusts which are introduced into the final reducing furnace 30 is less than 0.5wt%, sticking prevention effect
between the fine iron ores becomes reduced, while if the amount exceeds 1.0wt%, the gas distributor may be clogged
by the ultra fine dusts in next process.
[0062] It is preferable to control a velocity of the reducing gas in the pre-heating furnace 10, the pre-reducing furnace
20 and the final reducing furnace 30 in the range of 1.2~1.5 time of a minimum fluidizing velocity of the fine iron ores
which are staying in the furnaces. By maintaining the velocity of the reducing gas as above, the respective fluidized
bed reactors may form a stable bubbling fluidized bed.
[0063] Now, preferred embodiments are suggested to help the apparent understanding of the present invention. The
below embodiments are provided for the sake of clear understanding only and the present invention is not limited
thereto.
Embodiment
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[0064] The specification and experimental conditions for the smelting reduction apparatus of the preferred embodiment of the present invention is as follows.
1) Specification of the fluidized bed reactor (the pre-heating furnace, the pre-reducing furnace, and the final reducing
furnace)
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[0065]
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Radius of the lower cylindrical part: 0.3m
Radius of the upper cylindrical part: 0.6m
Height of the lower cylindrical part from the upper part of the gas distributor: 3m
Height of the upper cylindrical part from lower part of the inclination part: 3m
2) Fine iron ores
[0066]
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Particle size of the fine iron ores: under 10mm
Particle size distribution of the fine iron ores:
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under 0.125 mm: 15.5 %,
0.25~0.5 mm: 9.1%,
1.0~3.0 mm : 22.2%
5.0~8.0 mm: 13.7%
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Chemical composition of the fine iron ores
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0.125~0.25 mm: 10.0%,
0.5~1.0 mm : 9.2%,
3.0~5.0 mm : 19.5%
8.0~10.0 mm: 0.8%
T. Fe : 63.49wt%,
Al2O3: 2.33wt%,
P : 0.063%,
FeO : 0.37wt%,
Mn : 0.05wt%,
crystal water: 5.41wt%
SiO2 : 4.32wt%,
S :0.007wt%,
3) Reducing gas
[0067]
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Composition: CO : 65%, H2 : 25%, CO2 : 5%, N2 : 5%
Temperature: 750-850 °C
Pressure: 2.0 -3.0 barg
4) Chemical composition of the dusts
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T. Fe : 25-33wt%,
M. Fe : 10-15wt%,
MgO : 1-2%,
FeO: 10-15wt%,
Al2O3 : 2-5wt%,
C : 45-55wt%,
SiO2 : 8-10wt%,
CaO : 2-5wt%,
S : 1-5wt%,
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[0069] Several experiments were carried out with the smelting reduction apparatus to examine the reduction of the
fine iron ores.
[0070] The experimental results exhibited that reduced fine iron ores was begun to be discharged via the ore discharging duct 31 from the final reducing furnace 30 after 90 minutes from the beginning of the charging of the fine iron
ores from the charging bin 5 into the pre-heating furnace 10.
[0071] An average reduction degree of the fine iron ores which are discharged from the final reducing furnace 30
was exhibited 86~90%, very excellent. An average gas utilization degree was 30-35%, and the gas consumption rate
was 1350-1500Nm3/t-ore. Further, a difference of pressure between the upper part and the lower part of the gas distributor of the final reducing furnace 30 was maintained in the range of 20-30mbar, which was not increased even after
a long time. As above, the small difference of pressure between the upper and lower parts of the gas distributor means
that the clogging phenomenon of the gas distributor nozzle did not occur. Finally, the particle size distribution of the
reduced iron which is preliminary reduced and discharged finally was exhibited uniform, which means that the sticking
phenomenon between the fine iron ores did not occur in the respective fluidized bed reactors.
[0072] As shown from the result of the above embodiment, the smelting reduction apparatus according to the present
invention may effectively prevent the clogging phenomenon of the gas distributor nozzle due to the dusts which is apt
to occur in the related art fludized bed reactors.
[0073] Further, the sticking phenomenon between the reduced iron particles which may occur in the process of the
reduction of the fine iron ores may be prevented by supplying the dusts containing a lot of carbon into the fluidizing
bed reactors to coat the surfaces of the reduced iron.
[0074] While the present invention has been described in detail with reference to the preferred embodiment, those
skilled in the art will appreciate that various modifications and substitutions can be made thereto without departing
from the scope of the present invention as set forth in the appended claims.
Claims
1.
A smelting reduction apparatus for preventing sticking of charged fine iron ores in fluidized bed reactors, compris-
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ing:
a three-stage type fluidized bed reactors including ;
a) an ore charging duct mounted on a side of respective fluidized bed reactors for charging fine iron ores,
b) a gas supply duct mounted at a lower part of the respective fluidized bed reactors for supplying reducing
gas,
c) an ore discharge duct mounted on a side wall of the respective fluidized bed reactors for discharging
fine iron ores which are charged into the respective fluidized bed reactors and reactions thereof are finished,
d) a gas distributor mounted in the respective fluidized bed reactors for uniformly distributing the reducing
gas to the inner space of the respective fluidized bed reactors, and
e) a cyclone for separating fine iron ore particles from the exhausted gas, which is discharged from the
upper parts of the respective fluidized bed reactors, to supply the reducing gas to next reactor or release
outside and recycle the fine iron ore particles to the lower parts of the respective fluidized bed reactors;
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a melter-gasifier for manufacturing molten pig iron by finally reducing the fine iron ores of which reaction is
finished in a final fluidized reactor; and
a dust separating device, which performs separation of exhausted gas from the melter-gasifier into dusts and
reducing gas, so as to supply the separated reducing gas to a lower part of the final fluidized bed reactor,
dusts having a larger particle sizes in the separated dusts to the melter-gasifier again, and fine dusts having
a smaller particle sizes in the separated dusts to an upper part of a gas distributor of the final fluidized bed
reactor.
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2.
A smelting reduction apparatus of claim 1, wherein each of the fluidized bed reactors of the three-stage type
fluidized bed reactor is manufactured in a dual-stage cylindrical shape, in which a diameter of a lower part is small
and a diameter of an upper part is large so that lower and the upper parts are connected to each other slantingly.
3.
A smelting reduction apparatus of claim 2, wherein the diameter of the upper cylindrical part is larger than that of
the lower cylindrical part by 1.5~2.0 times.
4.
A smelting reduction apparatus of claim 3, wherein a height of the cylindrical lower parts is higher by 1.0~1.5 times
than that of the cylindrical upper parts,
5.
A smelting reduction apparatus of claim 4, wherein the inclination of the connection between the upper and lower
cylindrical parts is 20~30° with relation to a central axis of the fluidized bed reactors.
6.
A smelting reduction apparatus of claim 5, wherein a whole height of the fluidized bed reactors is larger than a
diameter of the lower cylindrical part by 10~20 times.
7.
A smelting reduction apparatus of claim 1 or claim 2, wherein the dust separation device includes at least two or
more cyclones and at least one or more dust storage bins, wherein a first cyclone of the cyclones is connected to
the upper part and the lower part of the melter-gasifier and an upper part of a second cyclone, the second cyclone
is connected to the lower part of the final fluidized bed reactor and an upper part of the dust storage bin, and the
dust storage bin is connected to an upper part of the gas distributor of the final fluidized bed reactor.
8.
A smelting reduction apparatus of claim 7, wherein the second cyclone and the dust storage bin is connected by
a dust supply duct which is mounted with a two-way valve, wherein the dust supply duct branched by the two-way
valve is connected to a dust supply duct which connects the first cyclone and the melter-gasifier.
9.
A smelting reduction apparatus of claim 8, wherein the dust storage bin part includes three dust storage bins
respectively connected to one another via the dust supply ducts.
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10. A smelting reduction apparatus of claim 9, wherein a dust supply duct which is positioned at a lower part of a first
dust storage bin is mounted with a nitrogen gas injection device, so that dusts stored in the first dust storage bin
may be conveyed to a second dust storage bin with high pressure.
11. A smelting reduction apparatus of claim 10, wherein a dust supply duct which is positioned at a lower part of a
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third dust storage bin is mounted with a nitrogen gas injection device, so that the dusts stored in the third dust
storage bin may be injected into the final reactor with high pressure.
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12. A smelting reduction apparatus of claim 11, wherein a dust supply duct connecting the lower part of the third dust
storage bin to the nitrogen gas injection device is mounted with a dust introducing feeder for controlling an amount
of dust supply to the final reactor.
13. A smelting reduction process in which fine iron ores are charged into a three-stage type fludizing bed reactor and
supplied with reducing gas for manufacturing sponge iron by reducing the charged fine iron ores, and molten pig
iron is manufactured by charging the sponge iron into a melter-gasifier, a process for manufacturing molten pig
iron by using the smelting reduction process characterized in that exhaust gas discharged from the melter-gasifier
is separated into reducing gas and dusts, the separated reducing gas is supplied to a lower part of a final fluidized
bed reactor, and fine dusts having a smaller particle sizes in the separated dusts are supplied to an upper part of
a gas distributor of the final fluidized bed reactor for coating fine iron ores which are in bubbling fluidization state
in the respective fluidizing bed reactors so as to prevent sticking of the fine iron ores to each other and to the gas
distributor .
14. A process for manufacturing molten pig iron of claim 13, wherein the fine dusts having a smaller particle sizes are
supplied to the final fluidized bed reactor by high pressure nitrogen.
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15. A process for manufacturing molten pig iron of claim 14, wherein the pressure of the nitrogen for conveying the
dust particles is higher than an internal pressure of the final fluidizing bed reactor by 2~3 times.
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16. A process for manufacturing molten pig iron of claim 15, wherein
an amount of the dusts which are injected into the final reducing furnace is to be 0.5~1.0wt% with relation
to an amount of raw iron ores which are initially charged into the fluidizing bed reactors.
17. A process for manufacturing molten pig iron of claim 16, wherein a velocity of the reducing gas in the fluidizing
bed reactors is to be 1.2~1.5 times of a minimum fluidizing velocity of the fine iron ores which are staying in the
fludizing bed reactors.
Patentansprüche
35
1.
Eine Schmelzreduktionsvorrichtung zur Verhinderung eines Anhaftens von eingefüllten Feineisenerzen in
Fließbettreaktoren, umfassend:
Fließbettreaktoren vom Dreistufentyp, die folgendes einschließen:
40
a) einen Erzbeschickungsschacht, der an einer Seite der entsprechenden Fließbettreaktoren angebracht
ist, zum Beschicken mit Feineisenerzen;
b) einen Gaszufuhrschacht, der an einem unteren Teil der entsprechenden Fließbettreaktoren angebracht
ist, zur Zuführung von Reduktionsgas;
45
c) einen Erzablaßschacht, der an einer Seitenwand der entsprechenden Fließbettreaktoren angebracht
ist, zum Ablassen von Feineisenerzen, die in die entsprechenden Fließbettreaktoren gefüllt sind und deren
Reaktionen beendet sind;
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d) einen Gasverteiler, der in den entsprechenden Fließbettreaktoren angebracht ist, zum gleichmäßigen
Verteilen des Reduktionsgases in den Innenraum der entsprechenden Fließbettreaktoren, und
e) einen Zyklon zum Trennen der Feineisenerzteilchen von der Abluft, die von den oberen Teilen der
entsprechenden Fließbettreaktoren abgeführt wird, um das Reduktionsgas dem nächsten Reaktor zuzuführen oder nach Außen abzulassen und die Feineisenerzteilchen zu den unteren Teilen der entsprechenden Fließbettreaktoren rückzuführen;
einen Schmelzofenvergaser zur Herstellung von geschmolzenem Roheisen durch ein abschließendes Redu-
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zieren der Feineisenerze, deren Reaktionen beendet sind, in einem abschließenden Fließreaktor reduziert;
und
eine Staubabtrennvorrichtung, die eine Trennung von Abluft von dem Schmelzofenvergaser in Stäube und
Reduktionsgas bewirkt, um so das abgetrennte Reduktionsgas einem unteren Teil des abschließenden
Fließbettreaktors, Stäube mit einer größeren Teilchengröße in den abgetrennten Stäuben wieder dem
Schmelzofenvergaser und Feinstäube mit einer kleineren Teilchengröße in den abgetrennten Stäuben einem
oberen Teil eines Gasverteilers des abschließenden Fließbettreaktors zuzuführen.
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2.
Eine Schmelzreduktionsvorrichtung nach Anspruch 1, wobei jeder der Fließbettreaktoren des Fließbettreaktors
vom Dreistufentyp in einer Z.weistufenzylinderform hergestellt ist, bei der ein Durchmesser eines unteren Teils
gering ist und ein Durchmesser eines oberen Teils groß ist, so daß unterer und oberer Teil schräg miteinander
verbunden sind.
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3.
Eine Schmelzreduktionsvorrichtung nach Anspruch 2, wobei der Durchmesser des oberen zylindrischen Teils
1,5~2,0-mal größer ist als der des unteren zylindrischen Teils.
4.
Eine Schmelzreduktionsvorrichtung nach Anspruch 3, wobei eine Höhe der zylindrischen unteren Teile 1,0~
1,5-mal höher ist als die der zylindrischen oberen Teile.
5.
Eine Schmelzreduktionsvorrichtung nach Anspruch 4, wobei die Neigung der Verbindung zwischen den oberen
und unteren zylindrischen Teilen 20~30° bezogen auf eine Mittelachse der Fließbettreaktoren ist.
6.
Eine Schmelzreduktionsvorrichtung nach Anspruch 5, wobei eine Gesamthöhe der Fließbettreaktoren 10~20-mal
größer ist als ein Durchmesser des unteren zylindrischen Teils.
7.
Eine Schmelzreduktionsvorrichtung nach Anspruch 1. oder Anspruch 2, wobei die Staubabtrennvorrichtung mindestens zwei oder mehrere Zyklone und mindestens einen oder mehrere Staublagerungsbunker einschließt, wobei
ein erster Zyklon der Zyklone mit dem oberen Teil und dem unteren Teil des Schmelzofenvergasers und einem
oberen Teil eines zweiten Zyklons verbunden ist, der zweite Zyklon mit dem unteren Teil des abschließenden
Fließbettreaktors und einem oberen Teil des Staublagerungsbunkers verbunden ist und der Staublagerungsbunker
mit einem oberen Teil des Gasverteilers des abschließenden Fließbettreaktors verbunden ist.
8.
Eine Schmelzreduktionsvorrichtung nach Anspruch 7, wobei der zweite Zyklon und der Staublagerungsbunker mit
einem Staubzuführschacht verbunden sind, der mit einem Zweiwegeventil ausgestattet ist, wobei der mittels des
Zweiwegeventils verzweigte Staubzuführschacht mit einem Staubzuführschacht verbunden ist, der den ersten
Zyklon und den Schmelzofenvergaser verbindet.
9.
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Eine Schmelzreduktionsvorrichtung nach Anspruch 8, wobei der Staublagerungsbunkerteil drei Staublagerungsbunker einschließt, die über die Staubzuführschächte jeweils miteinander verbunden sind.
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10. Eine Schmelzreduktionsvorrichtung nach Anspruch 9, wobei ein Staubzuführschacht, der an einem unteren Teil
eines ersten Staublagerungsbunker angeordnet ist, mit einer Stickstoffgaseinspeisungsvorrichtung montiert ist,
so daß Stäube, die in dem ersten Staublagerungsbunker gelagert sind, mit Hochdruck zu einem zweiten Staublagerungsbunker befördert werden können.
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11. Eine Schmelzreduktionsvorrichtung nach Anspruch 10, wobei ein Staubzuführschacht, der an einem unteren Teil
eines dritten Staublagerungsbunker angeordnet ist, mit einer Stickstoffgaseinspeisungsvorrichtung montiert ist,
so daß die Stäube, die in dem dritten Staublagerungsbunker gelagert sind, mit Hochdruck in den abschließende
Reaktor eingespeist werden können.
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12. Eine Schmelzreduktionsvorrichtung nach Anspruch 11, wobei ein Staubzuführschacht, der den unteren Teil des
dritten Staublagerungsbunker mit der Stickstoffgaseinspeisungsvorrichtung verbindet, mit einer Staubeinspeiseeinrichtung zur Steuerung einer Menge der Staubzuführung zu dem abschließende Reaktor montiert ist.
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13. Ein Schmelzreduktionsverfahren, bei dem Feineisenerze in einen Fließbettreaktor vom Dreistufentyp geladen werden und mit Reduktionsgas versorgt werden, zur Herstellung von Eisenschwamm durch Reduzieren der beschickten Feineisenerze, und geschmolzenes Roheisen hergestellt wird durch Laden des Eisenschwamms in einen
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Schmelzofenvergaser, wobei ein Verfahren zur Herstellung von geschmolzenem Roheisen unter Verwendung des
Schmelzreduktionsverfahrens dadurch charakterisiert ist, daß Abluft, die aus dem Schmelzofenvergaser abgelassen wird, in Reduktionsgas und Stäube getrennt wird, wobei das abgetrennte Reduktionsgas einem unteren
Teil eines abschließenden Fließbettreaktors zugeführt wird und feine Stäube mit einer kleineren Teilchengröße in
den abgetrennten Stäuben einem oberen Teil eines Gasverteilers in dem abschließenden Fließbettreaktor zugeführt werden zur Beschichtung von Feineisenerzen, die in den entsprechenden Fließbettreaktoren in einem blasenbildenden Fließzustand vorliegen, um so ein Haften der Feineisenerze aneinander und an den Gasverteiler
zu verhindern.
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14. Verfahren zur Herstellung von geschmolzenem Roheisen nach Anspruch 13, wobei die Feinstäube mit einer kleineren Teilchengröße mittels Hochdruckstickstoff dem abschließenden Fließbettreaktor zugeführt werden.
15. Verfahren zur Herstellung von eschmolzenem Roheisen nach Anspruch 14, wobei der Druck des Stickstoffs zur
Förderung der Staubteilchen 2~3-mal höher ist als der Innendruck des abschließenden Fließbettreaktors.
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16. Verfahren zur Herstellung von eschmolzenem Roheisen nach Anspruch 15, wobei eine Menge der Stäube, die in
den abschließenden Reduktionsofen eingespeist wird, 0,5~1,0 Gew.-% ist, bezogen auf eine Menge an Roheisenerzen, die anfänglich in die Fließbettreaktoren geladen wird.
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17. Verfahren zur Herstellung von eschmolzenem Roheisen nach Anspruch 16, wobei eine Geschwindigkeit des Reduktionsgases in den Fließbettreaktoren 1,2~1,5-mal eine Fluidisierungsminimalgeschwindigkeit der Feineisenerze ist, die sich in den Fließbettreaktoren befinden.
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Revendications
1.
Appareil de fusion-réduction pour empêcher l'agglutination de minerais fins de fer dans des réacteurs à lit fluidisé,
comprenant :
un réacteur à lit fluidisé de type à trois étages comprenant :
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a) un conduit de chargement de minerais monté sur un côté des réacteurs à lit fluidisé respectifs pour
charger les minerais fins de fer,
b) un conduit d'alimentation en gaz monté au niveau d'une partie inférieure des réacteurs à lit fluidisé
respectifs pour fournir du gaz de réduction,
c) un conduit de décharge de minerais monté sur une paroi latérale des réacteurs à lit fluidisé respectifs
pour décharger les minerais fins de fer qui sont chargés dans les réacteurs à lit fluidisé respectifs et dont
les réactions sont terminées,
d) un distributeur de gaz monté dans les réacteurs à lit fluidisé respectifs pour distribuer de manière
uniforme le gaz de réduction vers l'espace intérieur des réacteurs à lit fluidisé respectifs, et
e) un cyclone pour séparer les particules de minerais fins de fer du gaz évacué, qui est déchargé à partir
des parties supérieures des réacteurs à lit fluidisé respectifs, pour fournir le gaz de réduction au réacteur
suivant ou le libérer à l'extérieur et recycler les particules de minerais fins de fer vers les parties inférieures
des réacteurs à lit fluidisé respectifs ;
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un fondeur-gazogène pour fabriquer de la fonte en gueuse fondue en réduisant finalement les minerais fins
de fer dont la réaction est terminée dans un réacteur à lit fluidisé final ; et
un dispositif de séparation de poussière, qui réalise la séparation du gaz évacué à partir du fondeur-gazogène
en poussières et en gaz de réduction, afin de fournir le gaz de réduction séparé à une partie inférieure du
réacteur à lit fluidisé final, les poussières ayant une taille de particules plus grande dans les poussières séparées allant dans le fondeur-gazogène à nouveau, et les poussières fines ayant une taille de particules plus
petite dans les poussières séparées allant vers une partie supérieure d'un distributeur de gaz du réacteur à
lit fluidisé final.
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2.
Appareil de fusion-réduction selon la revendication 1, dans lequel chacun des réacteurs à lit fluidisé du réacteur
à lit fluidisé de type à trois étages est fabriqué en une forme cylindrique à double étage, dans laquelle un diamètre
d'une partie inférieure est petit et un diamètre d'une partie supérieure est grand afin que les parties inférieures et
supérieures soient connectées l'une à l'autre de façon oblique.
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3.
Appareil de fusion-réduction selon la revendication 2, dans lequel le diamètre de la partie cylindrique supérieure
est plus grand que celui de la partie cylindrique inférieure de 1,5 à 2,0 fois.
4.
Appareil de fusion-réduction selon la revendication 3, dans lequel une hauteur des parties inférieures cylindriques
est supérieure de 1,0 à 1,5 fois à celle des parties supérieures cylindriques.
5.
Appareil de fusion-réduction selon la revendication 4, dans lequel l'inclinaison de la connexion entre les parties
inférieures et supérieures cylindriques est de 20 à 30° par rapport à l'axe central des réacteurs à lit fluidisé.
6.
Appareil de fusion-réduction selon la revendication 5, dans lequel toute la hauteur des réacteurs à lit fluidisé est
supérieure à un diamètre de la partie cylindrique inférieure de 10 à 20 fois.
7.
Appareil de fusion-réduction selon la revendication 1 ou 2, dans lequel le dispositif de séparation de poussière
comprend au moins deux cyclones ou plus et au moins une trémie de stockage de poussières ou plus, dans lequel
un premier cyclone des cyclones est connecté à la partie supérieure et à la partie inférieure du fondeur-gazogène
et une partie supérieure d'un deuxième cyclone, le deuxième cyclone est connecté à la partir inférieure du réacteur
à lit fluidisé final et à une partie supérieure de la trémie de stockage de poussières, et la trémie de stockage de
poussières est connectée à une partie supérieure du distributeur de gaz du réacteur à lit fluidisé final.
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8.
Appareil de fusion-réduction selon la revendication 7, dans lequel le deuxième cyclone et la trémie de stockage
de poussières sont connectés par un conduit d'alimentation en poussières qui est monté avec une soupape bidirectionnelle, dans lequel le conduit d'alimentation en poussières branché par la soupape bidirectionnelle est connecté à un conduit d'alimentation en poussières qui connecte le premier cyclone au fondeur-gazogène.
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9.
Appareil de fusion-réduction selon la revendication 8, dans lequel la partie de trémie de stockage de poussières
comprend trois trémies de stockage de poussières respectivement connectées l'une à l'autre via les conduits
d'alimentation en poussières.
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10. Appareil de fusion-réduction selon la revendication 9, dans lequel un conduit d'alimentation en poussières qui est
positionné à une partie inférieure d'une première trémie de stockage de poussières est monté avec un dispositif
d'injection de gaz azote, afin que les poussières stockées dans la première trémie de stockage de poussières
puissent être transportées vers une deuxième trémie de stockage de poussières par haute pression.
11. Appareil de fusion-réduction selon la revendication 10, dans lequel un conduit d'alimentation en poussières qui
est positionné à une partie inférieure d'une troisième trémie de stockage de poussières est monté avec un dispositif
d'injection de gaz azote, afin que les poussières stockées dans la troisième trémie de stockage de poussières
puissent être injectées dans le réacteur final par haute pression.
12. Appareil de fusion-réduction selon la revendication 11, dans lequel un conduit d'alimentation en poussières connectant la partie inférieure de la troisième trémie de stockage de poussières au dispositif d'injection de gaz azote
est monté avec un dispositif d'alimentation introduisant de la poussière pour contrôler une quantité d'alimentation
en poussières du réacteur final.
13. Procédé de fusion-réduction dans lequel les minerais fins de fer sont chargés dans un réacteur à lit fluidisé de
type à trois étages et fournis avec un gaz de réduction pour fabriquer de l'éponge de fer en réduisant les minerais
fins de fer chargés, et la fonte en gueuse fondue est fabriquée en chargeant l'éponge de fer dans un fondeurgazogène, procédé de fabrication de fonte en gueuse fondue en utilisant le procédé de fusion-réduction caractérisé en ce que le gaz d'évacuation déchargé du fondeur-gazogène est séparé en gaz de réduction et poussières,
le gaz de réduction séparé est fourni à une partie inférieure d'un réacteur à lit fluidisé final, et les fines poussières
ayant une taille de particules plus grande dans les poussières séparées sont fournies à une partie supérieure d'un
distributeur de gaz du réacteur à lit fluidisé final à des fins de revêtement des minerais fins de fer qui sont dans
un état de fluidisation bouillonnant dans les réacteurs à lit fluidisé respectifs afin d'empêcher l'agglutination des
minerais fins de fer les uns aux autres et au distributeur de gaz.
14. Procédé de fabrication de fonte en gueuse fondue selon la revendication 13, dans lequel les poussières fines
ayant une taille de particules plus petite sont fournies au réacteur à lit fluidisé final par azote à haute pression.
15. Procédé de fabrication de fonte en gueuse fondue selon la revendication 14, dans lequel la pression de l'azote
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pour transporter les particules de poussières est supérieure à une pression interne du réacteur à lit fluidisé final
de 2 à 3 fois.
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16. Procédé de fabrication de fonte en gueuse fondue selon la revendication 15, dans lequel une quantité des poussières qui sont injectées dans le four de réduction final doit être de 0,5 à 1,0% en poids par rapport à une quantité
de minerais de fer bruts qui sont initialement chargés dans les réacteurs à lit fluidisé.
17. Procédé de fabrication de fonte en gueuse fondue selon la revendication 16, dans lequel une vitesse du gaz de
réduction dans les réacteurs à lit fluidisé doit être de 1,2 à 1,5 fois celle d'une vitesse de fluidisation minimale des
minerais fins de fer qui restent dans les réacteurs à lit fluidisé.
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