CN112063789A - Direct reduction iron-making method of flame-proof rotary hearth furnace - Google Patents
Direct reduction iron-making method of flame-proof rotary hearth furnace Download PDFInfo
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- CN112063789A CN112063789A CN202010858910.9A CN202010858910A CN112063789A CN 112063789 A CN112063789 A CN 112063789A CN 202010858910 A CN202010858910 A CN 202010858910A CN 112063789 A CN112063789 A CN 112063789A
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/08—Making spongy iron or liquid steel, by direct processes in rotary furnaces
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/0073—Selection or treatment of the reducing gases
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Abstract
The invention discloses a direct reduction iron-making method of a muffle rotary hearth furnace, belongs to the technical field of non-blast furnace iron-making, and solves the problems of low metallization rate, low flue gas utilization efficiency and high energy consumption of the conventional reduction iron-making method. The method of the invention comprises the following steps: uniformly mixing the iron-containing raw material, the flux and the coal powder according to a design proportion, directly loading the pressed or pelletized carbon-containing pellets into a heating chamber of a rotary hearth furnace, wherein the heating chamber is a heating section, and carrying out open flame preheating on the carbon-containing pellets by adopting combustion gas in the heating chamber; the preheated carbon-containing pellets enter the reduction chamber along with the rotation of the bottom of the rotary hearth furnace, the combustion gas in the combustion chamber above the reduction chamber is combusted, and the preheated carbon-containing pellets are subjected to flame isolation heating through the flame isolation plate, so that the iron oxide in the carbon-containing pellets and carbon are subjected to reduction reaction to generate reducing gas, and the metallized furnace burden is obtained. The iron-making method can be used for reducing iron-containing furnace burden.
Description
Technical Field
The invention belongs to the technical field of non-blast furnace iron making, and particularly relates to a direct reduction iron making method of a flame-proof rotary hearth furnace.
Background
Blast furnace iron making is the most important iron making process in the world at present, and has the characteristics of large production scale, low energy consumption, good pig iron quality, high efficiency and the like. However, blast furnace ironmaking presents two major problems: firstly, blast furnace iron making needs to consume a large amount of fuel, especially high-quality coke, and the shortage of coking coal resources and the high coke price restrict the blast furnace iron making production; secondly, blast furnace ironmaking CO2The emission is large, the environmental pollution is serious, and the global climate is warmed.
The non-blast furnace ironmaking technology is characterized in that the dependence of blast furnace ironmaking on coking coal resources is eliminated, and the non-coking coal ironmaking is utilized, wherein, the carbon-containing pellets in the furnace of the rotary hearth furnace ironmaking method are contacted with the coal gas, and along with the progress of reduction reaction, CO in the coal gas2The content is increased, the oxidation potential is increased, secondary oxidation is easy to occur, the metallization rate of the pellets is low (the metallization rate is generally 60-80%), the flue gas temperature is high, and the energy consumption is high.
Disclosure of Invention
In view of the analysis, the invention aims to provide a direct reduction iron-making method of a muffle rotary hearth furnace, which solves the problems of low metallization rate, low flue gas utilization efficiency and high energy consumption of the conventional reduction iron-making method.
The purpose of the invention is mainly realized by the following technical scheme:
the invention provides a direct reduction iron-making method of a muffle rotary hearth furnace, which comprises the following steps:
step 1: uniformly mixing the iron-containing raw material, the flux and the coal powder according to a design proportion, directly loading the pressed or pelletized carbon-containing pellets into a heating chamber of a rotary hearth furnace, wherein the heating chamber is a heating section, and carrying out open flame preheating on the carbon-containing pellets by adopting combustion gas in the heating chamber;
step 2: the preheated carbon-containing pellets enter the reduction chamber along with the rotation of the bottom of the rotary hearth furnace, the combustion gas in the combustion chamber above the reduction chamber is combusted, and the preheated carbon-containing pellets are subjected to flame isolation heating through the flame isolation plate, so that the iron oxide in the carbon-containing pellets and carbon are subjected to reduction reaction to generate reducing gas, and the metallized furnace burden is obtained.
Further, only air and/or oxygen is introduced into the heating chamber, and no additional gas is introduced.
Further, in the direct reduction iron-making method by the muffle rotary hearth furnace, the step 2 is followed by the following steps: reducing gas enters the heating chamber from the reducing chamber, and in the heating chamber, the reducing gas is partially combusted and/or is subjected to gas-based reduction with carbon-containing pellets in the heating chamber to generate flue gas, so that heat is provided for the heating chamber, and the flue gas is used for preheating the carbon-containing pellets.
Further, the flue gas reduction potential (volume of CO and CO) in the heating chamber2Volume to volume ratio of (V)CO/(VCO+VCO2) ) is 10% to 80%.
Furthermore, a smoke outlet is arranged at the charging end of the heating chamber and is connected with an induced draft fan, and the induced draft fan promotes the flow of the reduced coal gas and the reduced coal gas flows out of the smoke outlet.
Furthermore, the smoke outlet of the heating chamber is communicated with the combustion gas inlet of the combustion chamber.
Furthermore, the flue gas discharged from the flue gas outlet is communicated with the combustion gas inlet of the combustion chamber through cooling and dust removal in sequence.
Further, the inner space of the rotary hearth furnace is annular, and the heating section and the reduction section are both fan-shaped rings.
Furthermore, the central angle of the heating section is 120-240 degrees, and the sum of the central angle of the heating section and the central angle of the reduction section is 360 degrees.
Furthermore, a plurality of fire-retardant walls are arranged in the combustion chamber along the radial direction, the combustion chamber is divided into a plurality of combustion areas through the fire-retardant walls, and combustion gas is introduced into each combustion area.
Furthermore, each combustion area adopts heat accumulation type combustion, and the combustion temperature is 1000-1600 ℃.
Further, the combustion temperature was 1400 ℃.
Further, the flame barrier plate is a heat-resistant alloy plate or a silicon carbide plate.
Furthermore, the service temperature of the heat-resistant alloy plate is more than 1000 ℃, and the service temperature of the silicon carbide plate is more than 1200 ℃.
Furthermore, the thickness of the muffle plate is 30 mm-200 mm.
Furthermore, the direct reduction iron-making method of the muffle rotary hearth furnace adopts a direct reduction iron-making device of the muffle rotary hearth furnace, the device comprises the rotary hearth furnace, the inner space of the rotary hearth furnace is divided into a heating section and a reduction section by partition walls arranged along the radial direction along the circumferential direction of the rotary hearth furnace, the heating section is a heating chamber, the reduction section is divided into a reduction chamber and a combustion chamber positioned above the reduction chamber by a muffle plate along the axial direction of the rotary hearth furnace, the combustion chamber is independently arranged and is not communicated with the heating chamber and the reduction chamber, the heating chamber is provided with a charging hole, the reduction chamber is provided with a discharging hole, and combustion gas is introduced into the heating chamber and the combustion chamber.
Furthermore, the shape of the flame barrier is wave-shaped, or the shape of the flame barrier is flat plate-shaped, and a plurality of bulges or grooves are arranged on one side of the flat plate-shaped flame barrier facing the reduction chamber.
Furthermore, the shape of the flame isolation plate is flat plate shape, one side of the flame isolation plate, which faces the reduction chamber, is provided with a plurality of bulges, each bulge comprises a connecting rod and a heat transfer part, one end of each connecting rod is fixedly connected with the flame isolation plate, the other end of each connecting rod is connected with the heat transfer part, the heat transfer part is in a water drop shape, and the diameter of the heat transfer part is larger than that of the connecting rod.
Furthermore, the original iron-making device of the muffle rotary hearth furnace further comprises a heating chamber burner, and combustion gas of the heating chamber is introduced into the heating chamber through the heating chamber burner.
Furthermore, the heating chamber burner comprises a heating chamber connecting pipe and a heating chamber spray ball positioned at the end part of the heating chamber connecting pipe, a plurality of heating chamber spray holes are formed in the heating chamber spray ball, and air or oxygen is sprayed out from the heating chamber spray holes through the heating chamber connecting pipe.
Further, the direct reduction iron-making device of the muffle rotary hearth furnace further comprises a combustion chamber burner, and combustion gas in the combustion chamber is introduced into the combustion chamber through the combustion chamber burner.
Furthermore, the combustion chamber nozzle comprises a combustion chamber connecting pipe and a combustion chamber spray ball positioned at the end part of the combustion chamber connecting pipe, a plurality of combustion chamber spray holes are formed in the combustion chamber spray ball, and air or oxygen is sprayed out of the combustion chamber spray holes through the combustion chamber connecting pipe.
Furthermore, the burner of the combustion chamber is a regenerative burner.
Further, the combustion chamber is independently provided and is not communicated with the heating chamber and the reduction chamber.
Furthermore, the furnace wall of the rotary hearth furnace comprises a metal shell, a heat insulation layer, a heat preservation layer and a fire-resistant layer which are sequentially arranged from outside to inside.
Further, the metal shell is a steel shell.
Furthermore, the distance between one side of the flame isolating plate facing the reduction chamber and the bottom of the rotary hearth furnace is 50-500 mm.
Furthermore, the distance between the lower edge of the partition wall and the furnace bottom is 50 mm-300 mm.
Compared with the prior art, the invention can realize at least one of the following beneficial effects:
a) the technical core of the direct reduction iron-making method of the flame-proof rotary hearth furnace provided by the invention is to control the gas atmosphere in different areas and the combustion mode of the gas in different areas in the rotary hearth furnace, so that the carbon-containing pellets have high direct reduction metallization rate in the rotary hearth furnace and the gas can be efficiently utilized in the rotary hearth furnace, and the direct reduced iron with high metallization rate can be produced under the condition of low fuel consumption.
b) According to the direct reduction iron-making method of the flame-proof rotary hearth furnace, provided by the invention, the carbon-containing pellets respectively pass through the heating section and the reduction section, and the reduction section is divided into the reduction chamber and the combustion chamber, wherein the heating chamber adopts an open flame heating mode, the carbon-containing pellets in the heating chamber are contacted with combustion gas, and the open flame combustion is adopted, so that the rapid heating of the carbon-containing pellets can be realized, the temperature of the carbon-containing pellets can be basically close to the temperature required by reduction in the operation process of the heating chamber, the preheating of the carbon-containing pellets in the heating chamber is completed, and the production efficiency of the direct reduction iron-making method of; the reduction section adopts a flame-proof heating mode, and the flue gas generated by combustion is not contacted with the reduction pellets, so that the secondary oxidation of the reduced carbon-containing pellets can be avoided, and the high metallization rate can be obtained.
c) According to the direct reduction iron-making method of the flame-proof rotary hearth furnace, the reduction coal gas generated by the reduction chamber enters the heating chamber, the heating section burns the reduction coal gas, and the heat obtained by burning can be used for preheating the carbon-containing pellets.
d) According to the direct reduction iron-making method of the muffle rotary hearth furnace, the suitable temperature of coal-based reduction is 1000-1400 ℃, the suitable temperature of gas-based reduction is 700-1000 ℃, carbon-containing pellets are subjected to coal-based reduction in the reduction chamber, and in the preheating process of the carbon-containing pellets, the reduction coal gas returned from the reduction chamber can be subjected to gas-based reduction with iron ore powder on the surfaces of the carbon-containing pellets in the heating chamber, namely, the reduction coal gas in the reduction chamber is circulated to the heating chamber, so that the gas-based reduction and the coal-based reduction of the carbon-containing pellets can be realized, the metallization rate of the carbon-containing pellets can be further improved, and the coupling synergistic effect of the high-efficiency reduction of the carbon-containing pellets and the high-efficiency utilization. In addition, the circulation of the reducing coal gas can also reduce the smoke discharge of the direct reduction iron-making method of the muffle rotary hearth furnace.
e) The direct reduction iron-making method of the muffle rotary hearth furnace provided by the invention can not only quickly heat the carbon-containing pellets but also avoid CO by controlling the reduction potential of the flue gas in the heating chamber2And the reaction with C is carried out, so that the production efficiency of the direct reduction iron-making device of the muffle rotary hearth furnace is improved.
f) According to the direct reduction iron-making method of the flame-proof rotary hearth furnace, the smoke discharged from the heating chamber is used as the combustion gas of the combustion chamber, CO in the smoke is combusted in the combustion chamber to provide heat for the reduction chamber, so that the heat value of the smoke discharged from the heating chamber can be effectively utilized, and the step utilization of the energy of the direct reduction iron-making device of the flame-proof rotary hearth furnace is realized.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and drawings.
Drawings
The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention, wherein like reference numerals are used to designate like parts throughout.
FIG. 1 is a schematic structural diagram of a direct reduction iron-making apparatus of a muffle rotary hearth furnace according to an embodiment of the present invention;
FIG. 2 is a top view of a direct reduction iron-making apparatus of a muffle rotary hearth furnace according to an embodiment of the present invention;
FIG. 3 is a front view of a direct reduction iron-making apparatus of a muffle rotary hearth furnace according to an embodiment of the present invention;
FIG. 4 is a cross-sectional view A-A of FIG. 3;
FIG. 5 is a cross-sectional view B-B of FIG. 3;
FIG. 6 is a cross-sectional view C-C of FIG. 2;
FIG. 7 is a cross-sectional view taken along line D-D of FIG. 2;
fig. 8 is a schematic structural diagram of a muffle plate in a direct reduction iron-making apparatus of a muffle rotary hearth furnace according to an embodiment of the invention;
fig. 9 is a flowchart of a direct reduction iron-making method using a muffle rotary hearth furnace according to an embodiment of the present invention.
Reference numerals:
1-a rotary hearth furnace; 2-a feed inlet; 3-a flue gas outlet; 4-heating chamber burner; 5-burner of the combustion chamber; 6-partition wall; 7-fire retardant wall; 8-a discharge port; 9-furnace wall; 10-a combustion chamber; 11-flame isolation plate; 12-a reduction chamber; 13-furnace bottom; 14-a heating chamber; 15-a connecting rod; 16-heat transfer section.
Detailed Description
The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form a part hereof, and which together with the embodiments of the invention serve to explain the principles of the invention.
Example one
The invention provides a direct reduction iron-making method of a muffle rotary hearth furnace, which comprises the following steps with reference to fig. 9:
step 1: the method comprises the following steps of uniformly mixing an iron-containing raw material, a flux and coal powder according to a design proportion, directly loading the pressed or pelletized carbon-containing pellets into a heating chamber 14 of a rotary hearth furnace 1, wherein the heating chamber 14 is a heating section, and carrying out open flame preheating on the carbon-containing pellets by adopting combustion gas (such as air and/or oxygen) in the heating chamber 14;
step 2: the preheated carbon-containing pellets enter the reduction chamber 12 along with the rotation of the bottom of the rotary hearth furnace 1, the combustion gas in the combustion chamber 10 above the reduction chamber 12 is combusted, and the preheated carbon-containing pellets are subjected to flame isolation heating through the flame isolation plate 11, so that the iron oxide in the carbon-containing pellets and carbon are subjected to reduction reaction to generate reducing gas, and the metallized furnace burden is obtained.
It should be noted that, only air and/or oxygen is introduced into the heating chamber, and no additional gas is introduced.
Compared with the prior art, the technical core of the direct reduction iron-making method of the flame-proof rotary hearth furnace provided by the embodiment is to control the atmosphere of coal gas in different areas and the combustion mode of the coal gas in different areas in the rotary hearth furnace 1, so that carbon-containing pellets have high direct reduction metallization rate in the rotary hearth furnace 1, the coal gas can be efficiently utilized in the rotary hearth furnace 1, and direct reduced iron with high metallization rate can be produced under the condition of low fuel consumption.
Specifically, the carbon-containing pellets respectively pass through a heating section and a reduction section, the reduction section is divided into a reduction chamber 12 and a combustion chamber 10, wherein the heating chamber 14 adopts an open flame heating mode, the carbon-containing pellets in the heating chamber 14 are in contact with combustion gas, and the carbon-containing pellets are rapidly heated by adopting open flame combustion, so that the temperature required by reduction can be basically approached in the operation process of the heating chamber 14, the carbon-containing pellets are preheated in the heating chamber 14, and the production efficiency of the direct reduction iron-making method of the muffle rotary hearth furnace is improved; the reduction section adopts a flame-proof heating mode, and the flue gas generated by combustion is not contacted with the reduction pellets, so that the secondary oxidation of the reduced carbon-containing pellets can be avoided, and the high metallization rate can be obtained.
In order to further utilize the reducing gas generated in the reducing chamber 12, the step 2 is followed by the following steps: reducing gas (containing CO) enters the heating chamber 14 from the reducing chamber 12, and in the heating chamber 14, the reducing gas is partially combusted and/or is subjected to gas-based reduction with carbon-containing pellets in the heating chamber 14 to generate flue gas, so that heat is provided for the heating chamber 14 for preheating the carbon-containing pellets. The reducing gas generated by the reducing chamber 12 enters the heating chamber 14, the heating section burns the reducing gas, and the heat obtained by the combustion can be used for preheating the carbon-containing pellets. Meanwhile, the proper temperature of the coal-based reduction is 1000-1400 ℃, the proper temperature of the gas-based reduction is 700-1000 ℃, the carbon-containing pellets are subjected to the coal-based reduction in the reduction chamber 12, the reducing gas returned from the reduction chamber 12 can be subjected to the gas-based reduction with the iron ore powder on the surface of the carbon-containing pellets in the heating chamber 14 in the preheating process of the carbon-containing pellets, that is, the reducing gas in the reduction chamber 12 is circulated to the heating chamber 14, so that the gas-based reduction and the coal-based reduction of the carbon-containing pellets can be realized, the metallization rate of the carbon-containing pellets can be further improved, and the coupling synergistic effect of the high-efficiency reduction of the carbon-containing pellets and the high-efficiency utilization. In addition, the circulation of the reducing coal gas can also reduce the smoke discharge of the direct reduction iron-making method of the muffle rotary hearth furnace.
Notably, the CO within the heating chamber 142Too high a content may result in too high an oxidation potential, CO, in the heating chamber 142Reacts with C to reduce the C content in the carbon-containing pellets, is not beneficial to the reduction of the carbon-containing pellets in the reduction chamber 12, and therefore, the reduction potential (the volume of CO and the CO) of the flue gas in the heating chamber 142Volume to volume ratio of (V)CO/(VCO+VCO2) ) is controlled to 10% to 80%. By controlling the reduction potential of the flue gas in the heating chamber 14, not only can the carbonaceous pellets be heated quickly, but also CO can be avoided2And the reaction with C is carried out, so that the production efficiency of the direct reduction iron-making device of the muffle rotary hearth furnace is improved.
It can be understood that, in order to realize the further utilization of the reducing gas, the fume outlet 3 of the heating chamber 14 is arranged at the charging end of the heating chamber 14 (i.e. the end of the heating chamber 14 provided with the charging port 2), and the fume outlet 3 is connected with an induced draft fan (not shown in the figure), so that the flow of the reducing gas is promoted by the induced draft fan and flows out from the fume outlet 3.
Considering that the flue gas discharged from the heating chamber 14 contains CO and still has a high calorific value, the flue gas outlet 3 of the heating chamber 14 is communicated with the combustion gas inlet of the combustion chamber 10. The flue gas discharged from the heating chamber 14 is used as the combustion gas of the combustion chamber 10, and CO in the flue gas is combusted in the combustion chamber 10 to provide heat for the reduction chamber 12, so that the heat value of the flue gas discharged from the heating chamber 14 can be effectively utilized, and the stepped utilization of the energy of the direct reduction iron-making device of the flame-proof rotary hearth furnace is realized.
In order to improve the purity of the flue gas discharged from the heating chamber 14, the flue gas discharged from the flue gas outlet 3 is communicated with the combustion gas inlet of the combustion chamber 10 through cooling and dust removal in sequence. The flue gas of heating chamber 14 exhaust is through the cooling, can reduce the temperature of heating chamber 14 exhaust flue gas to the suitable temperature of dust remover, removes dust to the flue gas after the cooling, can get rid of the solid particulate matter in the flue gas to improve the purity of heating chamber 14 exhaust flue gas.
Illustratively, the inner space of the rotary hearth furnace 1 is annular, the heating section and the reduction section are both fan-shaped, and in order to ensure the preheating effect of the heating chamber 14 and the reduction effect of the reduction chamber 12, the central angle of the heating section is 120 ° to 240 °, such as 150 °, 180 °, 200 °, and 220 °, and the sum of the central angle of the heating section and the central angle of the reduction section is 360 °.
In order to be able to precisely control the temperature of the combustion chamber 10, a plurality of flame retardant walls 7, for example 2 or 3, are arranged radially inside the combustion chamber 10, by means of which flame retardant walls 7 the combustion chamber 10 is divided into a plurality of combustion zones, each of which is supplied with combustion gas.
Illustratively, each combustion area respectively adopts regenerative combustion, and the combustion temperature is 1000-1600 ℃ (for example, 1400 ℃).
In order to ensure the radiation heating effect of the flame isolation plate 11, the flame isolation plate 11 is a heat-resistant alloy plate or a silicon carbide plate and other materials with good heat conduction effect, wherein the long-term service temperature of the heat-resistant alloy plate is more than 1000 ℃, and the long-term service temperature of the silicon carbide plate is more than 1200 ℃; the thickness of the flame barrier 11 is 30 mm-200 mm, such as 50mm, 70mm, 100mm, 120mm, 150mm, 180 mm. This is because the thickness of the flame barrier 11 is too thin, the heat transfer is fast, and the radiation heating effect is good, but the strength of the flame barrier 11 is low, and the service life is short; the excessively thick thickness of the flame barrier 11 may affect the heat transfer of the flame barrier 11, resulting in poor radiation heating effect of the flame barrier 11.
Illustratively, the above-mentioned direct reduction iron-making method using a muffle rotary hearth furnace adopts a direct reduction iron-making device using a muffle rotary hearth furnace, referring to fig. 1 to 8, the device comprises a rotary hearth furnace 1, the inner space of the rotary hearth furnace 1 is divided into a heating section and a reduction section by a partition wall 6 arranged along the radial direction along the circumferential direction of the rotary hearth furnace 1, the heating section is a heating chamber 14, the reduction section is divided into a reduction chamber 12 and a combustion chamber 10 positioned above the reduction chamber 12 by a flame baffle 11 along the axial direction of the rotary hearth furnace 1, the combustion chamber 10 is arranged independently and is not communicated with the heating chamber 14 and the reduction chamber 12, the heating chamber 14 is provided with a charging opening 2, the reduction chamber 12 is provided with a discharging opening 8, and combustion gas is introduced into the heating chamber 14 and the combustion chamber 10.
In order to improve the radiation heating capability of the flame barrier 11, the flame barrier 11 is wave-shaped, or the flame barrier 11 is flat-plate-shaped, and a plurality of protrusions or grooves are arranged on one side of the flat-plate-shaped flame barrier 11 facing the reduction chamber 12, so that the radiation area of the flame barrier 11 can be increased by the self-shape (wave-shaped) of the flame barrier 11 or the protrusions or grooves are processed on the flame barrier 11, and the radiation heating capability of the flame barrier 11 is further improved.
Illustratively, the shape of the flame barrier 11 is a flat plate, the side of the flame barrier 11 facing the reduction chamber 12 is provided with a plurality of protrusions, and for the structure of the protrusions, specifically, the protrusions comprise a connecting rod 15 and a heat transfer part 16, one end of the connecting rod 15 is fixedly connected with the flame barrier 11, the other end of the connecting rod 15 is connected with the heat transfer part 16, the shape of the heat transfer part 16 is a drop, and the diameter of the heat transfer part 16 is larger than that of the connecting rod 15. In this way, the heat of the flame barrier 11 can be transferred to the heat transfer part 16 through the connecting rod 15, so that the heat transfer part 16 can be close to the carbon-containing pellets, and the reduction of the carbon-containing pellets is promoted; meanwhile, compared with the heat transfer part 16, the diameter of the connecting rod 15 is smaller, and the reducing gas in the reducing chamber 12 can flow between the connecting rods 15 after passing through the heat transfer part 16, which is equivalent to that the distance between the flame isolation plate 11 and the carbon-containing pellets is shortened on the basis of not influencing the reducing gas, and the reduction of the carbon-containing pellets is further promoted.
In order to realize the delivery of the combustion gas in the heating chamber 14, the direct iron-making device of the muffle rotary hearth furnace further comprises a heating chamber burner 4, and the combustion gas in the heating chamber 14 is introduced into the heating chamber 14 through the heating chamber burner 4.
In order to further improve the uniformity of the temperature distribution in the heating chamber 14, the structure of the heating chamber burner 4, specifically, the structure includes a heating chamber connection pipe and a heating chamber spray ball located at the end of the heating chamber connection pipe, the heating chamber spray ball is provided with a plurality of heating chamber spray holes, air or oxygen is sprayed from the heating chamber spray holes through the heating chamber connection pipe, and the plurality of heating chamber spray holes can provide the air or oxygen radiated from the center of the heating chamber spray ball, so that the uniformity of the temperature distribution in the heating chamber 14 can be further improved.
Similarly, in order to realize the transportation of the combustion gas in the combustion chamber 10, the direct reduction iron making apparatus of the muffle rotary hearth furnace further comprises a combustion chamber burner 5 (e.g., a regenerative burner), and the combustion gas in the combustion chamber 10 is introduced into the combustion chamber 10 through the combustion chamber burner 5.
In order to further improve the uniformity of the temperature distribution in the combustion chamber 10, the structure of the combustion chamber burner 5 specifically includes a combustion chamber connection pipe and a combustion chamber spray ball located at an end of the combustion chamber connection pipe, the combustion chamber spray ball is provided with a plurality of combustion chamber spray holes through which air or oxygen is sprayed from the combustion chamber spray holes, and the plurality of combustion chamber spray holes can provide air or oxygen radiated outward from the center of the combustion chamber spray ball, thereby further improving the uniformity of the temperature distribution in the combustion chamber 10.
In order to ensure the temperature of the inner space of the rotary hearth furnace 1, the furnace wall 9 of the rotary hearth furnace 1 comprises a metal shell (e.g., a steel shell), a heat insulation layer, an insulation layer and a fire-resistant layer which are arranged in sequence from outside to inside, wherein the fire-resistant layer is positioned on the innermost layer and can bear higher working temperature; the heat preservation layer and the heat insulation layer are positioned in the middle layer, so that the internal space of the rotary hearth furnace 1 can be effectively preserved heat, and the heat of the internal space of the rotary hearth furnace 1 is prevented from being diffused to the external environment; the metal shell is located on the outermost layer and is used for supporting and protecting the whole furnace wall 9 of the rotary hearth furnace 1.
In order to facilitate the flow of the reducing flue gas in the reducing chamber 12, the distance between one side of the flame barrier 11 facing the reducing chamber 12 (i.e. the lower end surface of the flame barrier 11) and the bottom 13 of the rotary hearth furnace 1 is 50 mm-500 mm, such as 70mm, 100mm, 120mm, 150mm, 180mm, 220mm, 250mm, 280mm, 350mm, 400mm, 420mm and 470 mm. This is because the distance between the side of the flame isolation plate 11 facing the reduction chamber 12 and the upper end surface of the furnace bottom 13 of the rotary hearth furnace 1 is too small, so that the space of the reduction chamber 12 is too small, which is not convenient for the flow of the reduction flue gas and is easy to cause too large pressure of the reduction flue gas; the distance between the side of the flame barrier 11 facing the reduction chamber 12 and the hearth 13 of the rotary hearth furnace 1 is too large, which results in poor radiation heating effect of the flame barrier 11.
In order to avoid the interference between the carbon-containing pellets and the partition wall 6 in the rotation process of the furnace bottom 13 of the rotary hearth furnace 1, the distance between the lower edge of the partition wall 6 and the furnace bottom 13 is 50 mm-300 mm, such as 70mm, 100mm, 120mm, 150mm, 180mm, 220mm, 250mm and 280 mm. This is because, by limiting the distance between the lower edge of the partition wall 6 and the hearth 13 to the above range, the carbonaceous pellets can easily interfere with the partition wall 6 during the rotation of the hearth 13 of the rotary hearth furnace 1, and the reduction gas can be promoted to smoothly flow into the heating chamber 14 through the partition wall 6.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.
Claims (10)
1. A direct reduction iron-making method of a muffle rotary hearth furnace is characterized by comprising the following steps:
step 1: uniformly mixing an iron-containing raw material, a flux and coal powder according to a design proportion, directly loading the pressed or pelletized carbon-containing pellets into a heating chamber of a rotary hearth furnace, wherein the heating chamber is a heating section, and carrying out open flame preheating on the carbon-containing pellets by adopting combustion gas in the heating chamber;
step 2: the preheated carbon-containing pellets enter the reduction chamber along with the rotation of the bottom of the rotary hearth furnace, the combustion gas in the combustion chamber above the reduction chamber is combusted, and the preheated carbon-containing pellets are subjected to flame isolation heating through the flame isolation plate, so that the iron oxide in the carbon-containing pellets and carbon are subjected to reduction reaction to generate reducing gas, and the metallized furnace burden is obtained.
2. The muffle rotary hearth furnace direct reduction ironmaking process according to claim 1, further comprising the following steps after step 2: reducing gas enters the heating chamber from the reducing chamber, and in the heating chamber, the reducing gas is partially combusted and/or is subjected to gas-based reduction with carbon-containing pellets in the heating chamber to generate flue gas, so that heat is provided for the heating chamber, and the flue gas is used for preheating the carbon-containing pellets.
3. The method of claim 2, wherein the combustion gas introduced into the heating chamber is air and/or oxygen, excluding coal gas.
4. The muffle rotary hearth furnace direct reduction ironmaking method according to claim 2, characterized in that the flue gas reduction potential in the heating chamber is 10-80%.
5. The direct reduction ironmaking process of the muffle rotary hearth furnace according to claim 2, wherein the flue gas outlet of the heating chamber is in communication with a combustion gas inlet of a combustion chamber.
6. The muffle rotary hearth furnace direct reduction iron making method according to any one of claims 1 to 5, characterized in that the central angle of the heating section is 120 ° to 240 °, and the sum of the central angle of the heating section and the central angle of the reduction section is 360 °.
7. The direct reduction iron-making method of the muffle rotary hearth furnace according to any one of claims 1 to 5, wherein a plurality of fire walls are radially arranged in the combustion chamber, the combustion chamber is divided into a plurality of combustion zones by the fire walls, and each combustion zone is introduced with combustion gas.
8. The direct reduction iron-making method by using the muffle rotary hearth furnace according to claim 7, wherein each combustion zone adopts regenerative combustion, and the combustion temperature is 1000-1600 ℃.
9. The direct reduction iron-making method by the muffle rotary hearth furnace according to any one of claims 1 to 5, wherein the muffle plate is a heat-resistant alloy plate or a silicon carbide plate;
the service temperature of the heat-resistant alloy plate is more than 1000 ℃, and the service temperature of the silicon carbide plate is more than 1200 ℃.
10. The direct reduction iron-making method of the muffle rotary hearth furnace according to the claim 1 to 5, characterized in that the direct reduction iron-making method of the muffle rotary hearth furnace adopts a direct reduction iron-making device of the muffle rotary hearth furnace, the device comprises the rotary hearth furnace, the inner space of the rotary hearth furnace is divided into a heating section and a reduction section along the circumferential direction of the rotary hearth furnace through partition walls arranged along the radial direction, the reduction section is divided into a reduction chamber and a combustion chamber positioned above the reduction chamber through a muffle plate along the axial direction of the rotary hearth furnace, the heating chamber is provided with a charging opening, the reduction chamber is provided with a discharging opening, and combustion gas is introduced into the heating chamber and the combustion chamber.
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