CN115875967A - Rotary kiln system and method for iron ore reduction co-production of reducing gas - Google Patents
Rotary kiln system and method for iron ore reduction co-production of reducing gas Download PDFInfo
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Abstract
The invention discloses a rotary kiln system and a method for iron ore reduction co-production of reducing gas, wherein a rotary kiln is sequentially divided into a drying section, a preheating section, a co-production reducing section, a roasting section and a slow cooling section, the spraying rhythm is effectively controlled through the combined action of a variable-diameter gas conveying channel arranged on the kiln wall and a gas spraying device, countercurrent steam is sprayed at the bottom of a material, carbon is fully gasified to produce synthesis gas, and the quality of the synthesis gas is improved through temperature and flow control. The invention adopts the novel rotary kiln and the smelting reduction furnace to be coupled, provides high-quality smelting reduction furnace charge with high pre-reduction degree to reduce the smelting reduction energy consumption, provides hydrogen-rich gas to realize hydrogen-based smelting reduction, improves the yield and efficiency of reduced iron, reduces carbon emission and saves carbon consumption, and is beneficial to boosting the development of the rotary kiln-smelting reduction process.
Description
Technical Field
The invention relates to metallurgical equipment and a method, in particular to a rotary kiln system for iron ore reduction co-production of reducing gas and a method for iron ore reduction co-production of reducing gas, and belongs to the technical field of metallurgy.
Background
The current metallurgical rotary kiln has a plurality of main purposes, and can be used for producing oxidized pellets, directly reducing iron, disposing and recycling solid waste resources and the like. The direct reduction of the coal-based rotary kiln is the most important, most valuable and widely applied process, is used for producing raw materials for electric furnace steelmaking in small scale, is used for treating dust, multi-metal composite ore and the like of iron and steel enterprises, and has the defects of influencing the normal production of the rotary kiln for years and seriously restricting the further development of the rotary kiln process due to the reasons of low yield, high energy consumption, easy ring formation and the like. The direct reduction of the conventional coal-based rotary kiln can be divided into two main zones, namely a preheating zone and a metallization zone, and a series of complex physical and chemical reactions such as water evaporation, carbon hydride released by coal pyrolysis, iron oxide-FeO-metallic iron and the like mainly occur.
Coal gasification refers to a process of converting solid coal into synthesis gas containing combustible gases such as CO, hydrogen, methane, etc. and non-combustible gases such as carbon dioxide, nitrogen, etc. by subjecting organic matters in coal to a series of chemical reactions with gasifying agents (such as steam/air and/or oxygen, etc.) at a certain temperature and pressure in a specific device. When coal is gasified, the gasification furnace, the gasification agent and the heat supply are all absent, the process flow is that air is firstly sent into the furnace, a part of fuel is burnt, heat is stored in the fuel layer and the heat storage chamber, then steam is introduced into the scorching heat fuel layer for reaction, and because of reaction heat absorption, when the temperature of the fuel layer and the heat storage chamber is reduced to a certain temperature, the air is sent into the furnace again for temperature rise, and the process is circulated.
The rotary kiln has been reported as a metallurgical equipment, and patent CN210916204U proposes a coal-based hydrogen metallurgical device for an iron ore rotary kiln, in which iron ore is reduced by H 2 Mainly, a gas discharge port of the rotary kiln is communicated with a gas inlet of a chain grate, an outlet end of an anaerobic cooling device is provided with a dry magnetic separator, a pellet discharge port of the dry magnetic separator is communicated with a dry grinding and dry separation device, a cold pressing device is further arranged at a discharge port of the dry grinding and dry separation device, and the dry grinding and dry separation device is provided with a cold pressing deviceThe carbon discharge port of the magnetic separator is communicated with the particle size classifier. Patent CN113881842B provides a system and method for integrally producing metallized pellets by pellet roasting and reduction, the system comprises a chain grate, a rotary kiln, a reduction zone and a finished product conveyor, a baffle is arranged at the joint of the rotary kiln and the reduction zone, a first hydrogen spray gun is arranged below the baffle, and a trolley arranged at the bottom of the reduction zone is provided with a plurality of second hydrogen spray guns for hydrogen-rich reduction of the metallized pellets. However, no report about the use of the rotary kiln as combined metallurgical and synthesis gas production equipment is found.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a rotary kiln system for reducing and coproducing reducing gas of iron ore and a method for reducing and coproducing reducing gas of iron ore, aiming at developing a novel rotary kiln device and realizing the purpose of new application of the rotary kiln on the basis of the prior rotary kiln device and process, wherein kiln gas transmission channels and embedded gas nozzles are uniformly distributed on the surface of a kiln body in the rotary kiln system and are used for blowing steam gasification agents and gas combustion supporting air into the kiln; high volatile coal and an iron-containing raw material (C/O = 1.2-1.5) are also adopted, and the material sequentially passes through a drying section, a preheating section, a co-production reduction section, a roasting section and a slow cooling section; blowing steam at the bottom of the material in a co-production reduction section, and carrying out water gas reaction on the steam and the fixed carbon of the granulated coal to generate H 2 CO, while the reduction of the iron-containing raw material takes place; and circulating hot air containing synthesis gas at the kiln tail to a burner at the kiln head to be used as fuel gas or circulating the hot air to a smelting reduction furnace to be used as reducing gas. The rotary kiln system has the function of producing synthesis gas while realizing direct reduction of iron oxide, can provide high-quality reducing materials for smelting reduction, and is favorable for promoting the development of a rotary kiln-smelting reduction process.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
according to a first embodiment of the present invention, there is provided a rotary kiln system for iron ore reduction co-production of reducing gas:
the rotary kiln system comprises a multi-section rotary kiln, and comprises a drying section, a preheating section, a combined reduction section, a roasting section and a slow cooling section which are sequentially connected in series from a kiln tail to a kiln head according to the trend of materials in the kiln. And a gasification agent nozzle is arranged on the kiln wall of the co-production reduction section. And a combustion-supporting gas nozzle is arranged on the kiln wall of the roasting section. The kiln head of the rotary kiln is provided with a burner which extends into the roasting section. An exhaust port at one end of the drying section close to the kiln tail is communicated with an air inlet outside the burner through an air circulation pipeline.
Preferably, a plurality of gasifying agent nozzles are uniformly arranged along the circumferential direction and the axial direction of the kiln wall at the co-production reduction section.
Preferably, a plurality of combustion-supporting gas nozzles are uniformly arranged along the circumferential direction and the axial direction of the kiln wall at the roasting section.
Preferably, a movable piston is independently arranged in any one of the gasifying agent nozzles and/or any one of the combustion gas nozzles. When the rotary kiln rotates, the movable piston enables: in the combined production reduction section, movable pistons in the gasification agent nozzles on the kiln wall below the material are in an open state, and movable pistons in the gasification agent nozzles on the other kiln walls are in a closed state. In the roasting section, the movable pistons in the gasifying agent nozzles on the kiln wall below the material are in a closed state, and the movable pistons in the gasifying agent nozzles on the other kiln walls are in an open state.
Preferably, the rotary kiln system also comprises a gasification agent conveying channel. The gasification agent conveying channel is arranged in the kiln wall of the rotary kiln, sequentially penetrates through the kiln walls of the drying section, the preheating section and the co-production reduction section along the direction from the kiln tail to the kiln head of the rotary kiln, and then is communicated with the gas inlet end of the gasification agent nozzle. The gasification agent conveying channel is a plurality of air inlet pore channels which are distributed along the axial direction of the rotary kiln. Preferably, a plurality of the gasifying agent supplying passages are communicated or not communicated with each other.
Preferably, the rotary kiln system further comprises a combustion assisting gas conveying channel. The combustion-supporting gas conveying passage is arranged in the kiln wall of the rotary kiln, sequentially penetrates through the kiln walls of the slow cooling section and the roasting section along the direction from the kiln head to the kiln tail of the rotary kiln and then is communicated with the gas inlet end of the combustion-supporting gas nozzle. The combustion-supporting gas conveying channel is a plurality of gas inlet pore channels which are distributed along the axial direction of the rotary kiln. Preferably, the combustion-supporting gas delivery passages are communicated or not communicated with each other.
Preferably, the pore size of the gasification agent conveying channel is gradually reduced along the direction from the kiln tail to the kiln head of the rotary kiln.
Preferably, the pore size of the combustion-supporting gas conveying channel is gradually reduced along the direction from the kiln head to the kiln tail of the rotary kiln.
Preferably, a pressurizing non-return mechanism is arranged in each of the gasifying agent conveying channel and the combustion-supporting gas conveying channel. The pressurizing non-return mechanism is a horn-shaped fixed bulge with a gradually reduced aperture along the airflow direction. Preferably, a plurality of pressurization non-return mechanisms are arranged in the gasification agent conveying channel and the combustion-supporting gas conveying channel, and the aperture of the exhaust holes of the plurality of pressurization non-return mechanisms is unchanged along the airflow direction or is gradually decreased in sequence.
Preferably, a pressurizing non-return mechanism is arranged in each of the gasifying agent conveying channel and the combustion-supporting gas conveying channel. The pressurizing non-return mechanism comprises fins, limiting protrusions and anchor cables. The fins are fan-shaped arc sheets matched with the gasifying agent conveying channel or the combustion-supporting gas conveying channel. The fins are hinged with the inner wall of the gasifying agent conveying channel or the inner wall of the combustion-supporting gas conveying channel. According to the trend of the airflow, the limiting bulge is arranged at the downstream of the fin and fixed on the inner wall of the gasifying agent conveying channel or the inner wall of the combustion-supporting gas conveying channel. One end of the anchor cable is fixedly connected with the limiting bulge, and the other end of the anchor cable is fixedly connected with the back surface of the fin. The length of the anchor cable is that when the anchor cable is extended to the maximum length, the included angle formed between the fin and the inner wall of the gasifying agent conveying channel or between the fin and the inner wall of the combustion-supporting gas conveying channel is 85-90 degrees, and preferably 90 degrees.
Preferably, the pressurizing non-return mechanism comprises a plurality of fins, the plurality of fins are distributed annularly along the circumferential direction of the inner wall of the gasifying agent conveying channel or the combustion-supporting gas conveying channel, and any one fin is independently provided with a limiting bulge and an anchor cable. When all the fins rotate towards the airflow direction and abut against the corresponding limiting protrusions, all the fins form a horn-shaped structure with the aperture gradually reduced along the airflow direction. Preferably, a plurality of pressurization non-return mechanisms are arranged in the gasification agent conveying channel and the combustion-supporting gas conveying channel, and when the fins of the plurality of pressurization non-return mechanisms form a horn-shaped structure, the aperture of the plurality of horn-shaped structure exhaust holes is unchanged along the airflow direction or is gradually decreased in sequence.
Preferably, the gasification agent conveying channel is also connected with a gasification agent conveying pipeline on an air inlet at the kiln tail, and the gasification agent conveying pipeline is provided with an air throttle and an adjusting pump.
Preferably, the combustion-supporting gas conveying passage is also connected with an oxygen-enriched gas conveying pipeline on a gas inlet at the kiln head, and an air valve and an air pump are arranged on the oxygen-enriched gas conveying pipeline.
Preferably, the rotary kiln system further comprises a smelting reduction furnace. And a kiln head discharge port of the rotary kiln is communicated with a feed port of the smelting reduction furnace through a material conveying device. And an exhaust port at the top of the smelting reduction furnace is communicated with an air inlet outside the burner through a furnace top gas conveying pipeline.
Preferably, a gas circulation branch pipe is further led out from the gas circulation pipeline and is communicated with a gas inlet of the smelting reduction furnace.
Preferably, the gas circulation pipeline is further provided with a dust removal device and a gas purification device in sequence. And the dust removal device and the gas purification device are both positioned at the upstream of the joint of the gas circulation branch pipe and the gas circulation pipeline.
According to a second embodiment of the present invention, there is provided a method for the co-production of reducing gas by iron ore reduction:
a method for the co-production of reducing gas by iron ore reduction or the co-production of reducing gas by iron ore reduction using the rotary kiln system according to the first embodiment, the method comprising the steps of:
(S1) conveying an iron-containing raw material and fuel into a rotary kiln, carrying out reduction treatment in sequence through a drying section, a preheating section, a co-production reduction section, a roasting section and a slow cooling section to obtain a reduced material, and conveying the reduced material into a melting reduction furnace for deep reduction treatment.
And (S2) in the reduction treatment process in the rotary kiln, spraying a gasifying agent into the kiln through a gasifying agent nozzle on the wall of the kiln of the co-production reduction section, and spraying combustion-supporting gas into the kiln through a combustion-supporting gas nozzle on the wall of the kiln of the roasting section.
And (S3) carrying out dust removal and purification treatment on hot air exhausted from the tail part of the rotary kiln, conveying the hot air to a roasting section through a gas circulation pipeline and a burner for participating in roasting treatment and/or conveying the hot air to a melting reduction furnace through the gas circulation pipeline and a gas circulation branch pipe for participating in deep reduction treatment, and conveying furnace top gas in the melting reduction furnace to the roasting section through a furnace top gas conveying pipeline and the burner for participating in roasting treatment.
Preferably, the iron-bearing raw material is natural lump ore and/or cold-bonded pellets. The fuel is lignite particles and/or bituminous coal particles. The iron-containing raw material and the fuel are added in such a ratio that C/O =1.2 to 1.5.
Preferably, the particle size of the iron-containing feedstock and the fuel are both 2 to 12mm, preferably 3 to 10mm, more preferably 4 to 8mm.
Preferably, the gasifying agent is steam or oxygen-enriched gas. The combustion-supporting gas is air or oxygen-enriched gas.
Preferably, the water vapour comprises low pressure steam and/or medium pressure steam, wherein: the low-pressure steam is water steam with the pressure not more than 3MPa and the temperature not more than 500 ℃, and preferably the water steam with the pressure not more than 2.5MPa and the temperature not more than 400 ℃. The medium-pressure steam is water steam with the pressure of 2.5-8MPa and the temperature of 400-800 ℃, and preferably water steam with the pressure of 3-6MPa and the temperature of 500-700 ℃.
Preferably, the temperature of the drying section is 150 to 400 ℃ (preferably 200 to 300 ℃). The temperature of the preheating section is 400-1000 ℃ (preferably 500-900 ℃). The temperature of the co-production reduction section is 1000-1300 ℃ (preferably 1050-1250 ℃). The temperature of the roasting section is 1300-1700 ℃ (preferably 1400-1600 ℃). The temperature of the slow cooling section is 900-1100 ℃ (preferably 9500-1050 ℃).
Preferably, the gasification agents sprayed into the kiln are specifically: during the rotation of the rotary kiln, the gasifying agent is sprayed into the material through the gasifying agent nozzle below the material.
Preferably, the injection of the combustion-supporting gas into the kiln is specifically as follows: in the rotary process of the rotary kiln, combustion-supporting gas is directly sprayed into a cavity above the material through a combustion-supporting gas nozzle above the material all the time.
In the prior art, the direct reduction process of the coal-based rotary kiln has the following reasons that the direct reduction process of the coal-based rotary kiln has high energy consumption, small production scale, easy ring formation and the like, the normal production of the rotary kiln is always influenced for many years and can only reach 15 ten thousand tons per year, the dust pollution is serious, the temperature field fluctuation along the direction of a kiln body is large, the temperature in the kiln cannot be measured and controlled in real time, the ring formation is easy, the reduction in the kiln is not uniform, the unqualified pellets are more, the production is unstable and the like, and in addition, the design of rotary kiln equipment is imperfect, the equipment failure rate is high, the operation experience is insufficient, almost all the coal-based rotary kilns stop production, and the further development of the rotary kiln process is severely restricted.
The invention innovatively provides a rotary kiln system for reducing and co-producing reducing gas of iron ore, wherein the rotary kiln comprises a drying section, a preheating section, a co-producing reducing section, a roasting section and a slow cooling section which are sequentially connected in series from a kiln tail to a kiln head, high-volatile coal and iron-containing raw materials are adopted, C/O = 1.2-1.5, the materials are sequentially subjected to drying, preheating, gasifying and reducing co-production, roasting and slow cooling for treatment, a gasifying agent nozzle arranged in the co-producing reducing section is used for blowing a steam gasifying agent into the kiln, and combustion-supporting air is blown into the kiln through a combustion-supporting air nozzle arranged in the roasting section. Steam is blown at the bottom of the material in the co-production reduction section, and the steam and the coal-fixed carbon in the material undergo water-gas reaction to generate H 2 CO, with pre-reduction of the iron-containing feedstock; and circulating hot air containing synthesis gas at the kiln tail to a burner at the kiln head to be used as fuel gas or circulating the hot air to the smelting reduction furnace to be used as reducing gas. The rotary kiln equipment has a new function of producing synthesis gas, provides high-quality pre-reduction materials for smelting reduction, and is beneficial to boosting the development of the rotary kiln process.
In the invention, the structure of the multi-channel gasification furnace is improved to increase the multiple channels (gasification agent conveying channels, gasification agent distribution channels and the like) uniformly distributed on the surface of the furnace body,Combustion-supporting gas conveying channel) and a gasification agent nozzle embedded in the inner wall of the kiln, change the proportion of iron materials and fuel in raw materials, develop a rotary kiln with new functions, and construct a kiln body structure integrating a drying zone, a preheating zone, a gasification and reduction zone, a combustion zone and a slow cooling zone; in addition, by controlling the blowing rhythm, countercurrent steam is blown to the bottom of the material to gasify carbon fully to produce synthetic gas (H) 2 And CO), improving the quality of the synthesis gas through temperature and flow control; by generating a hydrogen-rich reducing atmosphere (pure H under the same conditions) in the kiln 2 The speed of reducing the iron oxide in the atmosphere is higher than that in the pure CO atmosphere), thus promoting the pre-reduction of the iron oxide; the novel rotary kiln is coupled with the smelting reduction furnace, provides high-quality smelting reduction furnace charge with high pre-reduction degree to reduce the energy consumption of smelting reduction, and provides hydrogen-rich gas to realize the smelting reduction of hydrogen radicals.
In the invention, the gasification agent conveying channel is arranged in the kiln wall of the rotary kiln, sequentially penetrates through the kiln walls of the drying section, the preheating section and the co-production reduction section along the direction from the kiln tail to the kiln head of the rotary kiln, and then is communicated with the gas inlet end of the gasification agent nozzle. And the aperture size of the gasification agent conveying channel is gradually reduced along the direction from the kiln tail to the kiln head of the rotary kiln. Through the setting of the gasification agent transfer passage of reducing formula, can improve the pressure that finally enters into the gasification agent in the coproduction reduction section, make in the region of coproduction reduction section promptly, the atmospheric pressure in the gasification agent transfer passage is higher than the kiln internal gas pressure, the improvement of inside and outside atmospheric pressure difference, when being favorable to gasification agent to spout the effect, can also avoid in the kiln because the phenomenon of the hot-blast adverse current that leads to of high temperature to gasification agent transfer passage, powerful guarantee the emergence of coproduction reduction section water gas reaction, be favorable to H 2 Production of syngas per CO. And gas is directly sprayed into the kiln through a nozzle on the kiln body, so that the initial gas pressure of the gas is required to be always higher, otherwise, the high-temperature and high-pressure gas flow in the kiln is easy to flow reversely, and the gas spraying effect is poor.
In the invention, the combustion-supporting gas conveying channel is arranged in the kiln wall of the rotary kiln, sequentially penetrates through the kiln walls of the slow cooling section and the roasting section along the direction from the kiln head to the kiln tail of the rotary kiln and then is communicated with the gas inlet end of the combustion-supporting gas nozzle. Along the direction from the kiln head to the kiln tail of the rotary kiln, the aperture size of the combustion-supporting gas conveying channel is gradually reduced. Through the setting of the combustion-supporting gas transfer passage of reducing formula, can improve and finally enter into the pressure of combustion-supporting gas in the calcination section, even get in the region of calcination section, the atmospheric pressure in the combustion-supporting gas transfer passage is higher than the kiln internal gas pressure, the improvement of inside and outside atmospheric pressure difference when being favorable to combustion-supporting gas to spout the effect, can also avoid in the kiln because the phenomenon to combustion-supporting gas transfer passage is flowed against to the hot-blast adverse current that high temperature leads to, the calcination treatment effect of calcination section has been ensured.
In the invention, a pressurizing non-return mechanism is arranged in each of the gasifying agent conveying channel and the combustion-supporting gas conveying channel. The pressure boost non return mechanism is the fixed arch of loudspeaker form of aperture along air current direction convergent, perhaps pressure boost non return mechanism is for having the loudspeaker form structure that a plurality of fins constitute jointly. The arrangement of the pressurizing non-return mechanism can further improve the pressurizing effect of the gasifying agent and the combustion-supporting gas in the gasifying agent conveying channel and the combustion-supporting gas conveying channel respectively, further improve the air pressure of the gasifying agent and the combustion-supporting gas entering the kiln, and improve the gas spraying effect. Particularly, the pressurizing non-return mechanism with the fin structure can ensure that a plurality of fins which are circumferentially distributed and arranged at the same position in the gasifying agent conveying channel or the combustion-supporting gas conveying channel rotate in the downstream direction of the airflow and abut against the corresponding limiting protrusions to form a horn-shaped structure when the gas flows downstream, so that the downstream gas is pressurized, meanwhile, when the gas flows in a counter-flow manner, the fins rotate in the counter-flow direction of the airflow under the action of counter-flow gas, when the fins rotate to a certain degree (for example, an included angle formed between the fins and the inner wall of the gasifying agent conveying channel 3 or between the fins and the inner wall of the combustion-supporting gas conveying channel is 85-90 degrees and preferably 90 degrees), the anchor cable is straightened to the maximum length, so that the fins cannot further continue to rotate in the counter-flow direction of the gas, at the moment, all the fins are sealed and further avoid the gas loss, namely, the pressurizing non-return mechanism with the movable fin structure is adopted, so that the downstream pressurization of the gas and the automatic realization of the separation of the counter-flow gas can be automatically realized, the separation of the reaction without the control, the smooth operation and the strong safety and the integral strong operation guarantee system can be integrally formed.
In the invention, a movable piston is independently arranged in any one gasifying agent nozzle and/or any one combustion-supporting gas nozzle. The rotary kiln is rotated by a movable piston so that: in the combined production reduction section, movable pistons in the gasification agent nozzles on the kiln wall below the material are in an open state, and movable pistons in the gasification agent nozzles on the other kiln walls are in a closed state. In the roasting section, the movable pistons in the gasifying agent nozzles on the kiln wall below the material are in a closed state, and the movable pistons in the gasifying agent nozzles on the other kiln walls are in an open state. Namely, in the combined production reduction section, the movable piston controls the gasifying agent to be sprayed into the material layer to participate in the gasification reaction only from the gasifying agent nozzle positioned below the material. In the roasting section, the movable piston controls oxygen-enriched gas to be sprayed to the upper part of the material from the combustion-supporting gas nozzle when the oxygen-enriched gas is positioned below and above the material to participate in combustion reaction.
In the invention, when the multi-section rotary kiln is adopted for iron ore reduction and combined production of reducing gas, the fuel is granulated coal, the volatile content of young coal (lignite or bituminous coal) with high volatile content of the granulated coal is required to be about 30 percent (preferably 25 to 35 percent), the iron-containing raw material is natural rich lump ore and/or cold consolidation pellets (prepared from iron ore concentrate, composite ore, refractory ore and various iron-containing wastes), and the iron-containing raw material is required to have good reducibility, low reducing pulverization and high softening temperature; the proportion of the granulated coal is required to be higher than that of the iron-containing raw material (C/O = 1.2-1.5), and the particle sizes of the granulated coal and the iron-containing raw material are both 2-12mm (preferably 3-10mm, more preferably 4-8 mm); the filling rate is higher than that of a conventional rotary kiln (30-40 percent), and the height of the material layer is more than 80 cm.
In the present invention, from the feed end to the discharge end of the rotary kiln, the materials (iron-containing raw material and fuel) are sequentially subjected to a drying section (150 to 400 ℃, preferably 200 to 300 ℃), a preheating section (400 to 1000 ℃, preferably 500 to 900 ℃), a co-production reduction section (1000 to 1300 ℃, preferably 1050 to 1250 ℃), a roasting section (1300 to 1700 ℃, preferably 1400 to 1600 ℃), and a slow cooling section (900 to 1100 ℃, preferably 9500 to 1050 ℃). The iron-containing raw material is subjected to self free water and bound water removal at a drying end, so that high-temperature bursting is prevented from generating powder; the iron-containing raw material is consolidated and strengthened in the preheating section, and the granular coal is removed most of volatile components in the preheating section to produce hydrocarbon oxides and hydrocarbons.
In the invention, after materials (iron-containing raw materials and fuel) enter a co-production reduction section, air injection devices for injecting gasification agents are uniformly arranged in the area along the axial direction and the axial direction of the rotary kiln, and the gasification agents comprise low-pressure or medium-pressure steam and high-oxygen gas; low-pressure steam (steam with pressure not more than 3MPa and temperature not more than 500 ℃, preferably steam with pressure not more than 2.5MPa and temperature not more than 400 ℃), and medium-pressure steam (steam with pressure of 2.5-8MPa and temperature of 400-800 ℃, preferably steam with pressure of 3-6MPa and temperature of 500-700 ℃). The kiln wall between the gasification agent conveying channel and the inner cavity of the rotary kiln is used as a boundary, the air injection device is of an internal and external through structure, the external part is a movable piston, and the internal part is a gasification agent nozzle. The air injection device rotates along with the rotary kiln, when the air injection device is positioned in a material movement interval and is covered by materials, the movable piston is opened, and the gasification agent is injected into a material layer by the atomization nozzle; when the gasification furnace leaves the material interval, the movable piston is closed, and the gasification agent is not injected, so that the influence on the components of the synthesis gas is avoided.
Further, when the gasifying agent is steam, the steam enters the material layer through the gasifying agent nozzle, the steam is fully contacted with the granular coal, the water gas reaction starts to occur under the action of normal pressure and high temperature, the reaction formula is shown as follows, each reaction is a reversible reaction, and CO and H in the system 2 、H 2 O、CO 2 、CH 4 Four gases are present, the overall process is strongly endothermic, requiring heat supply:
C+H 2 O＝CO+H 2 +131.39 KJ/mol (1)
CO+H 2 O＝CO 2 +H 2 -41.19 KJ/mol (2)
C+2H 2 ＝CH 4 -74.90 KJ/mol (3)
furthermore, as an alternative to adjusting the conditions inside the kiln: when the heat of the water gas reaction is insufficient, the gasifying agent is adjusted to be water vapor containing part of oxygen-enriched gas or all oxygen-enriched gas, the water vapor enters the material layer through the gasifying agent nozzle, oxygen and the granular coal undergo combustion reaction, complete combustion is taken as the main part, and a large amount of heat is rapidly released to improve the temperature of a gasification and reduction zone.
In the present invention, in the co-production reduction stage, the iron oxides of the iron-containing raw material are all pre-reduced to FeO and metallic iron, consuming part of the H 2 And CO due to H 2 And CO may increase the reducing atmosphere concentration around the iron-containing material, thereby increasing the pre-reduction rate of the iron-containing material. Therefore, the area is a hydrogen/carbon combined metallurgical process with high integration of water gasification carbon and iron oxide reduction in a hot state, and the involved reactions are as follows:
3Fe 2 O 3 +CO＝2Fe 3 O 4 +CO 2 (4)
3Fe 2 O 3 +H 2 ＝2Fe 3 O 4 +H 2 O (5)
Fe 3 O 4 +CO＝3FeO+CO 2 (6)
Fe 3 O 4 +H 2 ＝3FeO+H 2 O (7)
FeO+CO＝Fe+CO 2 (8)
FeO+H 2 ＝Fe+H 2 O (9)
in the invention, the temperature of the roasting section is 1300-1700 ℃ (preferably 1400-1600 ℃), the main function is to provide heat for the co-production reduction section through the radiation heat transfer and the convection heat transfer of hot flue gas, and the heat source is the heat release of gas combustion. One part of the fuel gas source is furnace top gas produced by the melting reduction furnace, and the other part is synthesis gas produced by the rotary kiln per se for circulating combustion. The area is provided with an air injection device (combustion-supporting gas nozzle) for combustion-supporting air injection, secondary air is provided for gas combustion, the kiln wall can be properly cooled to reduce the risk of high-temperature ring formation, and fine particles such as granulated coal ash, iron-containing dust and the like are prevented from being adhered to the kiln wall to form a ring by virtue of the gas scouring effect.
In the invention, the pre-reduced iron-containing raw material and the residual coal are subjected to moderate slow cooling in the rotary kiln and then are used as the raw materials of the smelting reduction furnace after passing through the hot screen, so that the material temperature is improved, and the reduction degree and metallization rate of the iron-containing raw material are improved. The synthesis gas generated by the rotary kiln is introduced into a molten pool as reducing gas for smelting reduction, so that hydrogen radical smelting reduction is realized, and carbon consumption in the smelting reduction process is reduced.
In the present invention, the deep reduction process of the smelting reduction furnace causes the reaction of iron oxide and carbon to generate iron, carbon monoxide and part of carbon dioxide, and the specific reaction is as follows: fe x O(s)+C＝xFe(s)+CO(g)+CO 2 (g) In that respect The reaction process produces high temperature carbon monoxide and carbon dioxide gas, referred to as "high temperature gas" or "top gas". The high-temperature coal gas generated in the melting furnace has a temperature of more than 1400 ℃ and a maximum temperature of more than 1700 ℃, and has a certain pressure except a large amount of unreacted CO and H 2 In addition, it also contains a large amount of CO 2 And steam, the main components of which are CO (about 21%), CO 2 (about 25%), H 2 (about 4%), N 2 (about 48%), H 2 O (about 2%). In the technical scheme of the invention, the heat and the calorific value of the high-temperature coal gas are fully utilized, the rotary kiln needs a high-temperature environment and reducing gas, and the high-temperature top coal gas generated by the smelting reduction furnace is returned to the rotary kiln to serve as a reducing agent, and simultaneously, the heat of the part of gas is fully utilized, so that the maximum utilization of resources is realized.
Compared with the prior art, the invention has the following beneficial technical effects:
1: the rotary kiln is divided into a drying section, a preheating section, a co-production reduction section, a roasting section and a slow cooling section in sequence to construct a kiln body structure integrating a drying area, a preheating area, a gasification and reduction area, a combustion area and a slow cooling area; and a gasification agent injection device and a combustion-supporting gas injection device are respectively arranged on the kiln wall, so that the pre-reduction of materials in a co-production reduction section is realized while co-production is carried out to obtain high-quality H 2 the/CO synthesis gas improves the reducing atmosphere in the kiln, and is beneficial to the reduction of the iron oxide.
2: the invention also improves the reduction degree and metallization rate of the iron-containing raw material by using the high-quality synthesis gas moving in the multi-section rotary kiln to circulate through the gas circulation pipeline for combustion of the roasting section and the smelting reduction furnace and improving the reducing atmosphere of the roasting section and the smelting reduction furnace, and the smelting reduction furnace realizes hydrogen-based smelting reduction and is beneficial to reducing the carbon consumption in the smelting reduction process.
3: the invention effectively controls the blowing rhythm through the combined action of the variable-diameter gas conveying channel and the gas blowing device, and blows countercurrent steam at the bottom of the material to fully gasify carbon to produce synthesis gas (H) 2 And CO), and syngas quality is improved by temperature and flow control.
4: the rotary kiln can realize the generation of hydrogen-rich reducing atmosphere when the iron oxide in the kiln is reduced, so that the iron oxide contains H under the same condition 2 The speed of reducing the iron oxide in the atmosphere is higher than that in the pure CO atmosphere, and the pre-reduction of the iron oxide is promoted.
5: the invention adopts the novel rotary kiln to be coupled with the smelting reduction furnace, provides high-quality smelting reduction furnace charge with high pre-reduction degree to reduce the smelting reduction energy consumption, provides hydrogen-rich gas to realize hydrogen-based smelting reduction, improves the yield and efficiency of reduced iron, and simultaneously reduces carbon emission and saved carbon consumption.
Drawings
Fig. 1 is a schematic view of the construction of a rotary kiln system according to the present invention.
Fig. 2 is an enlarged schematic structural view of the fixed protrusion type pressurizing check mechanism of the invention.
FIG. 3 is an enlarged schematic view of the downstream flared finned pressurizing non-return mechanism of the present invention.
Fig. 4 is an enlarged structural schematic diagram of the closed reverse flow of the finned pressurizing non-return mechanism.
Fig. 5 is a schematic view of the overall structure of the rotary kiln system of the present invention with a smelting reduction furnace.
Fig. 6 is a process flow diagram for iron ore reduction co-production of reducing gas according to the present invention.
Reference numerals: 1: a rotary kiln; 101: a drying section; 102: a preheating section; 103: co-producing a reduction section; 104: a roasting section; 105: a slow cooling section; 106: a gasifying agent nozzle; 107: a combustion supporting gas nozzle; 108: burning a nozzle; 109: a gas circulation line; 110: a movable piston; 111: a gas circulation branch pipe; 2: a smelting reduction furnace; 3: a gasification agent delivery passage; 301: a gasification agent delivery conduit; 302: an air throttle; 303: adjusting the pump; 4: a combustion-supporting gas delivery passage; 401: an oxygen-enriched gas delivery conduit; 402: an air valve; 403: an air pump; 5: a pressurizing non-return mechanism; 501: a fin; 502: a limiting bulge; 503: an anchor cable; 6: a feeding device; 7: a top gas delivery conduit; 8: a dust removal device; 9: a gas purification device.
Detailed Description
The technical solution of the present invention is illustrated below, and the claimed scope of the present invention includes, but is not limited to, the following examples.
The rotary kiln system comprises a rotary kiln 1, wherein the rotary kiln 1 is a multi-section rotary kiln, and according to the trend of materials in the rotary kiln, the rotary kiln 1 comprises a drying section 101, a preheating section 102, a co-production reduction section 103, a roasting section 104 and a slow cooling section 105 which are sequentially connected in series from the tail of the rotary kiln to the head of the rotary kiln. And a gasification agent nozzle 106 is arranged on the kiln wall of the co-production reduction section 103. And the kiln wall of the roasting section 104 is provided with an oxidant gas nozzle 107. The kiln head of the rotary kiln 1 is provided with a burner 108 extending into the roasting section 104. An exhaust port at one end of the drying section 101 close to the kiln tail is communicated with an air inlet outside the burner 108 through an air circulation pipeline 109.
Preferably, a plurality of gasification agent nozzles 106 are uniformly arranged along the circumferential direction and the axial direction of the kiln wall at the combined production and reduction section 103.
Preferably, a plurality of oxidant gas nozzles 107 are uniformly arranged along the circumferential direction and the axial direction of the kiln wall at the roasting section 104.
Preferably, a movable piston 110 is independently provided inside each of the gasifying agent nozzles 106 and/or each of the combustion gas nozzles 107. The rotary kiln 1 is rotated by a movable piston 110 so that: in the combined production reduction section 103, the movable pistons 110 in the gasification agent nozzles 106 on the kiln wall below the material are in an open state, and the movable pistons 110 in the gasification agent nozzles 106 on the other kiln walls are in a closed state. In the roasting section 104, the movable pistons 110 in the gasifying agent nozzles 106 on the kiln wall below the material are in a closed state, and the movable pistons 110 in the gasifying agent nozzles 106 on the other kiln wall are in an open state.
Preferably, the rotary kiln system also comprises a gasification agent conveying channel 3. The gasification agent conveying channel 3 is arranged in the kiln wall of the rotary kiln 1, sequentially penetrates through the kiln walls of the drying section 101, the preheating section 102 and the co-production reduction section 103 along the direction from the kiln tail to the kiln head of the rotary kiln 1, and then is communicated with the gas inlet end of the gasification agent nozzle 106. The gasification agent conveying channel 3 is a plurality of air inlet pore channels which are distributed along the axial direction of the rotary kiln 1. Preferably, a plurality of the gasifying agent supplying passages 3 are communicated with each other or not.
Preferably, the rotary kiln system further comprises a combustion assisting gas conveying passage 4. The combustion-supporting gas conveying passage 4 is arranged in the kiln wall of the rotary kiln 1, sequentially penetrates through the kiln walls of the slow cooling section 105 and the roasting section 104 along the direction from the kiln head to the kiln tail of the rotary kiln 1, and then is communicated with the gas inlet end of the combustion-supporting gas nozzle 107. The combustion-supporting gas conveying channel 4 is a plurality of gas inlet channels which are distributed along the axial direction of the rotary kiln 1. Preferably, the combustion-supporting gas delivery passages 4 are communicated or not communicated with each other.
Preferably, the pore size of the gasification agent conveying channel 3 is gradually reduced along the direction from the kiln tail to the kiln head of the rotary kiln 1.
Preferably, the pore size of the combustion-supporting gas conveying passage 4 is gradually reduced along the direction from the kiln head to the kiln tail of the rotary kiln 1.
Preferably, a pressurizing non-return mechanism 5 is arranged in each of the gasifying agent conveying channel 3 and the combustion-supporting gas conveying channel 4. The pressurizing non-return mechanism 5 is a horn-shaped fixed bulge with a gradually reduced aperture along the airflow direction. Preferably, a plurality of pressure boosting check mechanisms 5 are arranged in the gasifying agent conveying channel 3 and the combustion-supporting gas conveying channel 4, and the aperture of the exhaust holes of the pressure boosting check mechanisms 5 is unchanged along the airflow direction or is gradually decreased in sequence.
Preferably, a pressurizing non-return mechanism 5 is arranged in each of the gasifying agent conveying channel 3 and the combustion-supporting gas conveying channel 4. The pressurizing check mechanism 5 comprises a fin 501, a limiting protrusion 502 and an anchor cable 503. The fins 501 are fan-shaped arc sheets matched with the gasifying agent conveying channel 3 or the combustion-supporting gas conveying channel 4. The fins 501 are hinged with the inner wall of the gasifying agent conveying channel 3 or the inner wall of the combustion-supporting gas conveying channel 4. According to the trend of the airflow, the limiting bulge 502 is arranged at the downstream of the fin 501 and fixed on the inner wall of the gasifying agent conveying channel 3 or the inner wall of the combustion-supporting gas conveying channel 4. One end of the anchor cable 503 is fixedly connected with the limiting protrusion 502, and the other end is fixedly connected with the back of the fin 501. The length of the anchor line 503 is such that when the anchor line 503 is extended to the maximum length, the angle formed between the fin 501 and the inner wall of the gasifying agent transporting passage 3 or the inner wall of the combustion-supporting gas transporting passage 4 is 85 to 90 degrees, preferably 90 degrees.
Preferably, the pressure boost non-return mechanism 5 includes a plurality of fins 501, the plurality of fins 501 are annularly distributed along the circumferential direction of the inner wall of the gasifying agent conveying channel 3 or the combustion-supporting gas conveying channel 4, and any one of the fins 501 is independently provided with a limiting protrusion 502 and an anchor cable 503. When all the fins 501 rotate towards the airflow direction and abut against the corresponding limiting protrusions 502, all the fins 501 form a horn-shaped structure with a bore diameter gradually reduced along the airflow direction. Preferably, a plurality of pressure boosting check mechanisms 5 are arranged in the gasifying agent conveying channel 3 and the combustion-supporting gas conveying channel 4, and when the fins 501 of the pressure boosting check mechanisms 5 form a horn-shaped structure, the aperture of the plurality of horn-shaped structure exhaust holes is unchanged along the airflow direction or is gradually decreased in sequence.
Preferably, the gasification agent delivery channel 3 is further connected to an air inlet at the kiln tail, and a gasification agent delivery pipe 301 is provided with a throttle 302 and a regulating pump 303.
Preferably, an oxygen-enriched gas conveying pipeline 401 is further connected to the gas inlet of the combustion-supporting gas conveying channel 4 at the kiln head, and an air valve 402 and an air pump 403 are arranged on the oxygen-enriched gas conveying pipeline 401.
Preferably, the rotary kiln system further comprises a smelting reduction furnace 2. And a kiln head discharge port of the rotary kiln 1 is communicated with a feed port of the smelting reduction furnace 2 through a material conveying device 6. The top exhaust port of the smelting reduction furnace 2 is communicated with the air inlet outside the burner 108 through a top gas conveying pipeline 7.
Preferably, the gas circulation line 109 is further provided with a gas circulation branch pipe 111 communicating with the gas inlet of the smelting reduction furnace 2.
Preferably, the gas circulation pipe 109 is further provided with a dust removing device 8 and a gas purifying device 9 in sequence. The dust removing device 8 and the gas cleaning device 9 are both located upstream of the connection of the gas circulation branch pipe 111 and the gas circulation pipe 109.
Example 1
As shown in fig. 1 to 5, the rotary kiln system for iron ore reduction and reduction gas co-production comprises a rotary kiln 1, wherein the rotary kiln 1 is a multi-section rotary kiln, and according to the direction of materials in the kiln, the rotary kiln 1 comprises a drying section 101, a preheating section 102, a co-production reduction section 103, a roasting section 104 and a slow cooling section 105 which are sequentially connected in series from the tail of the kiln to the head of the kiln. And a gasification agent nozzle 106 is arranged on the kiln wall of the co-production reduction section 103. And a combustion-supporting gas nozzle 107 is arranged on the kiln wall of the roasting section 104. The kiln head of the rotary kiln 1 is provided with a burner 108 extending into the roasting section 104. An exhaust port at one end of the drying section 101 close to the kiln tail is communicated with an air inlet outside the burner 108 through an air circulation pipeline 109.
Example 2
Example 1 is repeated except that a plurality of gasifying agent nozzles 106 are uniformly arranged along the circumferential direction and the axial direction of the kiln wall at the combined-production reducing section 103.
Example 3
Example 2 was repeated except that a plurality of oxidant gas nozzles 107 were uniformly arranged along the circumferential direction and the axial direction of the kiln wall at the firing section 104.
Example 4
Example 3 is repeated except that the inside of any one of the gasifying agent nozzles 106 and/or any one of the combustion gas nozzles 107 is independently provided with a movable piston 110. The rotary kiln 1 is rotated by a movable piston 110 so that: in the combined production reduction section 103, the movable pistons 110 in the gasification agent nozzles 106 on the kiln wall below the material are in an open state, and the movable pistons 110 in the gasification agent nozzles 106 on the other kiln walls are in a closed state. In the roasting section 104, the movable pistons 110 in the gasifying agent nozzles 106 on the kiln wall below the material are in a closed state, and the movable pistons 110 in the gasifying agent nozzles 106 on the other kiln wall are in an open state.
Example 5
Example 4 was repeated except that the rotary kiln system further included a gasifying agent delivery path 3. The gasification agent conveying channel 3 is arranged in the kiln wall of the rotary kiln 1, sequentially penetrates through the kiln walls of the drying section 101, the preheating section 102 and the co-production reduction section 103 along the direction from the kiln tail to the kiln head of the rotary kiln 1, and is communicated with the gas inlet end of the gasification agent nozzle 106. The gasification agent conveying channel 3 is a plurality of air inlet pore channels which are distributed along the axial direction of the rotary kiln 1.
Example 6
Example 5 was repeated except that the plurality of gasifying agent supplying passages 3 were not communicated with each other.
Example 7
Example 6 is repeated except that the rotary kiln system further comprises a combustion aid gas delivery channel 4. The combustion-supporting gas conveying passage 4 is arranged in the kiln wall of the rotary kiln 1, sequentially penetrates through the kiln walls of the slow cooling section 105 and the roasting section 104 along the direction from the kiln head to the kiln tail of the rotary kiln 1, and then is communicated with the gas inlet end of the combustion-supporting gas nozzle 107. The combustion-supporting gas conveying channel 4 is a plurality of gas inlet pore channels which are distributed along the axial direction of the rotary kiln 1.
Example 8
Example 7 was repeated except that the plurality of oxidant gas delivery passages 4 were not in communication with each other.
Example 9
Example 8 is repeated except that the pore size of the gasifying agent conveying passage 3 is gradually reduced along the direction from the kiln tail to the kiln head of the rotary kiln 1.
Example 10
Example 9 is repeated except that the pore size of the oxidant gas conveying passage 4 is gradually reduced along the direction from the head to the tail of the rotary kiln 1.
Example 11
Example 10 was repeated except that the gasifying agent delivery path 3 and the combustion-supporting gas delivery path 4 were both provided with a pressurizing non-return mechanism 5. The pressurizing non-return mechanism 5 is a horn-shaped fixing protrusion with a gradually reduced aperture along the airflow direction.
Example 12
Example 11 is repeated except that a plurality of pressurizing check mechanisms 5 are arranged in the gasifying agent conveying channel 3 and the combustion-supporting gas conveying channel 4, and the aperture of the exhaust holes of the plurality of pressurizing check mechanisms 5 is sequentially decreased progressively along the airflow direction.
Example 13
Example 12 was repeated except that the gasifying agent supplying passage 3 and the combustion-supporting gas supplying passage 4 were each provided therein with a pressurizing non-return mechanism 5. The pressurizing check mechanism 5 comprises a fin 501, a limiting protrusion 502 and an anchor cable 503. The fins 501 are fan-shaped arc sheets matched with the gasifying agent conveying channel 3 or the combustion-supporting gas conveying channel 4. The fins 501 are hinged with the inner wall of the gasifying agent conveying channel 3 or the inner wall of the combustion-supporting gas conveying channel 4. According to the trend of the airflow, the limiting bulge 502 is arranged at the downstream of the fin 501 and fixed on the inner wall of the gasifying agent conveying channel 3 or the inner wall of the combustion-supporting gas conveying channel 4. One end of the anchor cable 503 is fixedly connected with the limiting protrusion 502, and the other end is fixedly connected with the back of the fin 501. The length of the anchor rope 503 is such that when the anchor rope 503 is extended to the maximum length, the included angle formed between the fin 501 and the inner wall of the gasifying agent conveying passage 3 or between the fin 501 and the inner wall of the combustion-supporting gas conveying passage 4 is 90 °.
Example 14
The embodiment 13 is repeated, except that the pressurized non-return mechanism 5 includes a plurality of fins 501, the plurality of fins 501 are annularly distributed along the circumferential direction of the inner wall of the gasifying agent conveying channel 3 or the combustion-supporting gas conveying channel 4, and any one of the fins 501 is independently provided with a limiting protrusion 502 and an anchor cable 503. When all the fins 501 rotate towards the airflow direction and abut against the corresponding limiting protrusions 502, all the fins 501 form a horn-shaped structure with a bore diameter gradually reduced along the airflow direction. Preferably, a plurality of pressure boosting check mechanisms 5 are arranged in the gasifying agent conveying channel 3 and the combustion-supporting gas conveying channel 4, and when the fins 501 of the pressure boosting check mechanisms 5 form a horn-shaped structure, the aperture of the plurality of horn-shaped structure exhaust holes is sequentially decreased progressively along the airflow direction.
Example 15
The embodiment 14 is repeated, except that the gasification agent delivery channel 3 is also connected with a gasification agent delivery pipeline 301 on the air inlet at the kiln tail, and the gasification agent delivery pipeline 301 is provided with a throttle valve 302 and an adjusting pump 303.
Example 16
The embodiment 15 is repeated, except that the oxygen-enriched gas conveying pipeline 401 is also connected to the gas inlet of the combustion-supporting gas conveying channel 4 at the kiln head, and an air valve 402 and an air pump 403 are arranged on the oxygen-enriched gas conveying pipeline 401.
Example 17
Example 16 was repeated except that the rotary kiln system further included a smelting reduction furnace 2. And a kiln head discharge port of the rotary kiln 1 is communicated with a feed port of the smelting reduction furnace 2 through a material conveying device 6. The top exhaust port of the smelting reduction furnace 2 is communicated with the air inlet outside the burner 108 through a top gas conveying pipeline 7.
Example 18
Example 17 was repeated except that the gas circulation line 109 was further provided with a gas circulation branch pipe 111 communicating with the gas inlet of the smelting reduction furnace 2.
Example 19
Example 18 was repeated except that the gas circulation line 109 was further provided with a dust removing device 8 and a gas cleaning device 9 in this order. The dust removing device 8 and the gas cleaning device 9 are both located upstream of the connection of the gas circulation branch pipe 111 and the gas circulation pipe 109.
Example 20
As shown in fig. 6, a method for the co-production of reducing gas by iron ore reduction, the method comprising the steps of:
(S1) conveying an iron-containing raw material and fuel into a rotary kiln 1, sequentially carrying out reduction treatment on the iron-containing raw material and the fuel through a drying section 101, a preheating section 102, a co-production reduction section 103, a roasting section 104 and a slow cooling section 105 to obtain a reduced material, and conveying the reduced material into a smelting reduction furnace 2 for deep reduction treatment.
(S2) during the reduction treatment in the rotary kiln 1, a gasifying agent is sprayed into the kiln through the gasifying agent nozzles 106 on the kiln wall of the co-production reduction section 103, and combustion-supporting gas is sprayed into the kiln through the combustion-supporting gas nozzles 107 on the kiln wall of the roasting section 104.
(S3) carrying out dust removal and purification treatment on hot air exhausted from the tail of the rotary kiln 1, conveying the hot air to a roasting section 104 through a gas circulation pipeline 109 and a burner 108 to participate in roasting treatment and/or conveying the hot air to a melting reduction furnace 2 through the gas circulation pipeline 109 and a gas circulation branch pipe 111 to participate in deep reduction treatment, and conveying top gas in the melting reduction furnace 2 to the roasting section 104 through a top gas conveying pipeline 7 and the burner 108 to participate in roasting treatment.
The iron-containing raw materials are natural lump ore and cold-bonded pellets. The fuel is lignite particles and bituminous coal particles.
The iron-containing feedstock and fuel have a particle size in the range of 4-8mm.
The gasifying agent is water vapor. The combustion-supporting gas is air.
The water vapor comprises low pressure steam and medium pressure steam, wherein: the low-pressure steam is water steam with the pressure not more than 2.5MPa and the temperature not more than 400 ℃. The medium-pressure steam is water steam with the pressure of 3-6MPa and the temperature of 500-700 ℃.
Preferably, the temperature of the drying section 101 is 200 to 300 ℃. The temperature of the preheating section 102 is 500-900 ℃. The temperature of the co-production reduction section 103 is 1000-1300 ℃. The temperature of the roasting section 104 is 1400-1600 ℃. The temperature of the slow cooling section 105 is 950-1050 ℃.
The gasification agent sprayed into the kiln specifically comprises: during the rotation of the rotary kiln 1, the gasifying agent is always directly sprayed into the material through the gasifying agent nozzles 106 positioned below the material.
The injection of combustion-supporting gas into the kiln specifically comprises the following steps: during the rotation of the rotary kiln 1, the combustion-supporting gas is always directly injected into the chamber above the material through the combustion-supporting gas nozzle 107 above the material.
By adopting the process method of embodiment 20 to perform reduction treatment of the iron-containing raw material for multiple times and co-produce to obtain synthesis gas, compared with the traditional coal-based rotary kiln (without co-production synthesis gas mechanism), the metallization rate of the obtained reduced material is improved by about 2-4%, and the total carbon consumption is reduced by about 60% -80%; meanwhile, the ring forming phenomenon of the rotary kiln is obviously improved, and the integral production efficiency is improved by about 10 to 20 percent.
Claims (16)
1. A rotary kiln system for iron ore reduction and combined production of reducing gas is characterized in that: the rotary kiln system comprises a rotary kiln (1), wherein the rotary kiln (1) is a multi-section rotary kiln, and according to the trend of materials in the rotary kiln, the rotary kiln (1) comprises a drying section (101), a preheating section (102), a co-production reduction section (103), a roasting section (104) and a slow cooling section (105) which are sequentially connected in series from a kiln tail to a kiln head; a gasification agent nozzle (106) is arranged on the kiln wall of the co-production reduction section (103); a combustion-supporting gas nozzle (107) is arranged on the kiln wall of the roasting section (104); a burner (108) extending into the roasting section (104) is arranged on the kiln head of the rotary kiln (1); an exhaust port at one end of the drying section (101) close to the kiln tail is communicated with an air inlet outside the burner (108) through an air circulation pipeline (109).
2. The rotary kiln system as recited in claim 1, wherein: a plurality of gasifying agent nozzles (106) are uniformly arranged along the circumferential direction and the axial direction of the kiln wall at the co-production reduction section (103); and/or
A plurality of combustion-supporting gas nozzles (107) are uniformly arranged along the circumferential direction and the axial direction of the kiln wall at the roasting section (104);
preferably, a movable piston (110) is independently arranged in any one gasifying agent nozzle (106) and/or any one combustion gas nozzle (107); the rotary kiln (1) is rotated by a movable piston (110) such that: in the combined production reduction section (103), movable pistons (110) in the gasification agent nozzles (106) on the kiln wall below the material are in an open state, and movable pistons (110) in the gasification agent nozzles (106) on the other kiln walls are in a closed state; in the roasting section (104), the movable pistons (110) in the gasifying agent nozzles (106) on the kiln wall below the material are in a closed state, and the movable pistons (110) in the gasifying agent nozzles (106) on the other kiln walls are in an open state.
3. The rotary kiln system as claimed in claim 1 or 2, wherein: the rotary kiln system also comprises a gasification agent conveying channel (3); the gasification agent conveying channel (3) is arranged in the kiln wall of the rotary kiln (1), sequentially penetrates through the kiln walls of the drying section (101), the preheating section (102) and the co-production reduction section (103) along the direction from the kiln tail to the kiln head of the rotary kiln (1), and is communicated with the gas inlet end of the gasification agent nozzle (106); the gasification agent conveying channel (3) is a plurality of air inlet pore passages which are distributed along the axial direction of the rotary kiln (1); preferably, a plurality of the gasifying agent delivery passages (3) are communicated or not communicated with each other.
4. The rotary kiln system as recited in claim 3, wherein: the rotary kiln system also comprises a combustion assisting gas conveying channel (4); the combustion-supporting gas conveying channel (4) is arranged in the kiln wall of the rotary kiln (1), sequentially penetrates through the kiln walls of the slow cooling section (105) and the roasting section (104) along the direction from the kiln head to the kiln tail of the rotary kiln (1), and is communicated with the gas inlet end of the combustion-supporting gas nozzle (107); the combustion-supporting gas conveying channel (4) is a plurality of gas inlet pore passages which are distributed along the axial direction of the rotary kiln (1); preferably, the combustion-supporting gas conveying passages (4) are communicated or not communicated with each other.
5. The rotary kiln system as recited in claim 4, wherein: the aperture size of the gasification agent conveying channel (3) is gradually reduced along the direction from the kiln tail to the kiln head of the rotary kiln (1); and/or
Along the direction from the kiln head to the kiln tail of the rotary kiln (1), the pore size of the combustion-supporting gas conveying channel (4) is gradually reduced.
6. The rotary kiln system as claimed in claim 4 or 5, wherein: a pressurizing non-return mechanism (5) is arranged in each of the gasifying agent conveying channel (3) and the combustion-supporting gas conveying channel (4); the pressurizing non-return mechanism (5) is a horn-shaped fixed bulge with a gradually reduced aperture along the airflow direction; preferably, a plurality of pressurization check mechanisms (5) are arranged in the gasification agent conveying channel (3) and the combustion-supporting gas conveying channel (4), and the aperture of the exhaust hole of each of the plurality of pressurization check mechanisms (5) is unchanged along the airflow direction or is gradually decreased in sequence.
7. The rotary kiln system as claimed in claim 4 or 5, wherein: a pressurizing non-return mechanism (5) is arranged in each of the gasifying agent conveying channel (3) and the combustion-supporting gas conveying channel (4); the pressurizing check mechanism (5) comprises a fin (501), a limiting protrusion (502) and an anchor cable (503); the fins (501) are fan-shaped arc sheets matched with the gasifying agent conveying channel (3) or the combustion-supporting gas conveying channel (4); the fins (501) are hinged with the inner wall of the gasifying agent conveying channel (3) or the inner wall of the combustion-supporting gas conveying channel (4); according to the trend of the airflow, the limiting bulge (502) is arranged at the downstream of the fin (501) and fixed on the inner wall of the gasifying agent conveying channel (3) or the inner wall of the combustion-supporting gas conveying channel (4); one end of an anchor cable (503) is fixedly connected with the limiting bulge (502), and the other end of the anchor cable is fixedly connected with the back of the fin (501); the length of the anchor cable (503) is that when the anchor cable (503) is extended to the maximum length, the included angle between the fin (501) and the inner wall of the gasifying agent conveying channel (3) or the inner wall of the combustion-supporting gas conveying channel (4) is 85-90 degrees, and preferably 90 degrees.
8. The rotary kiln system as recited in claim 7, wherein: the pressurizing non-return mechanism (5) comprises a plurality of fins (501), the plurality of fins (501) are distributed annularly along the circumferential direction of the inner wall of the gasifying agent conveying channel (3) or the combustion-supporting gas conveying channel (4), and any one fin (501) is independently provided with a limiting bulge (502) and an anchor cable (503); when all the fins (501) rotate towards the airflow direction and abut against the corresponding limiting protrusions (502), all the fins (501) form a horn-shaped structure with the aperture gradually reduced along the airflow direction; preferably, a plurality of pressurizing non-return mechanisms (5) are arranged in the gasifying agent conveying channel (3) and the combustion-supporting gas conveying channel (4), and when the fins (501) of the plurality of pressurizing non-return mechanisms (5) form a horn-shaped structure, the aperture of the plurality of horn-shaped structure exhaust holes is unchanged along the airflow direction or is gradually decreased in sequence.
9. The rotary kiln system according to any one of claims 4-8, wherein: a gasification agent conveying pipeline (301) is further connected to the air inlet of the gasification agent conveying channel (3) at the kiln tail, and an air throttle (302) and an adjusting pump (303) are arranged on the gasification agent conveying pipeline (301); and/or
The combustion-supporting gas conveying passage (4) is also connected with an oxygen-enriched gas conveying pipeline (401) on a gas inlet at the kiln head, and an air valve (402) and an air pump (403) are arranged on the oxygen-enriched gas conveying pipeline (401).
10. The rotary kiln system as claimed in any one of claims 1 to 9, wherein: the rotary kiln system also comprises a smelting reduction furnace (2); a kiln head discharge port of the rotary kiln (1) is communicated with a feed port of the smelting reduction furnace (2) through a material conveying device (6); an exhaust port at the top of the smelting reduction furnace (2) is communicated with an air inlet outside the burner (108) through a furnace top gas conveying pipeline (7);
preferably, a gas circulation branch pipe (111) is further led out from the gas circulation pipeline (109) and is communicated with a gas inlet of the smelting reduction furnace (2).
11. The rotary kiln system as recited in claim 10, wherein: the gas circulating pipeline (109) is also sequentially provided with a dust removal device (8) and a gas purification device (9); the dust removal device (8) and the gas purification device (9) are both positioned at the upstream of the joint of the gas circulation branch pipe (111) and the gas circulation pipeline (109).
12. A method for co-producing reducing gas by iron ore reduction or iron ore reduction using the rotary kiln system according to any one of claims 1 to 11, characterized in that: the method comprises the following steps:
(S1) conveying an iron-containing raw material and fuel into a rotary kiln (1), sequentially performing reduction treatment through a drying section (101), a preheating section (102), a co-production reduction section (103), a roasting section (104) and a slow cooling section (105) to obtain a reduced material, and conveying the reduced material into a smelting reduction furnace (2) for deep reduction treatment;
(S2) in the reduction treatment process in the rotary kiln (1), a gasifying agent is sprayed into the kiln through a gasifying agent nozzle (106) on the kiln wall of the co-production reduction section (103), and combustion-supporting gas is sprayed into the kiln through a combustion-supporting gas nozzle (107) on the kiln wall of the roasting section (104);
(S3) carrying out dust removal and purification treatment on hot air exhausted from the tail of the rotary kiln (1), then conveying the hot air to a roasting section (104) through a gas circulation pipeline (109) and a burner (108) to participate in roasting treatment and/or conveying the hot air to a smelting reduction furnace (2) through the gas circulation pipeline (109) and a gas circulation branch pipe (111) to participate in deep reduction treatment, and conveying top gas in the smelting reduction furnace (2) to the roasting section (104) through a top gas conveying pipeline (7) and the burner (108) to participate in roasting treatment.
13. The method of claim 12, wherein: the iron-containing raw material is natural lump ore and/or cold-bonded pellets; the fuel is lignite particles and/or bituminous coal particles; the adding ratio of the iron-containing raw material to the fuel is such that C/O = 1.2-1.5;
preferably, the iron-containing feedstock and the fuel each have a particle size of from 2 to 12mm, preferably from 3 to 10mm, more preferably from 4 to 8mm.
14. The method according to claim 12 or 13, characterized in that: the gasification agent is water vapor or oxygen-enriched gas; the combustion-supporting gas is air or oxygen-enriched gas;
preferably, the water vapour comprises low pressure steam and/or medium pressure steam, wherein: the low-pressure steam is water steam with the pressure not more than 3MPa and the temperature not more than 500 ℃, and preferably the water steam with the pressure not more than 2.5MPa and the temperature not more than 400 ℃; the medium-pressure steam is water steam with the pressure of 2.5-8MPa and the temperature of 400-800 ℃, and preferably water steam with the pressure of 3-6MPa and the temperature of 500-700 ℃.
15. The method according to any one of claims 12-14, wherein: the temperature of the drying section (101) is 150-400 ℃ (preferably 200-300 ℃); the temperature of the preheating section (102) is 400-1000 ℃ (preferably 500-900 ℃); the temperature of the co-production reduction section (103) is 1000-1300 ℃ (preferably 1050-1250 ℃); the temperature of the roasting section (104) is 1300-1700 ℃ (preferably 1400-1600 ℃); the temperature of the slow cooling section (105) is 900-1100 ℃ (preferably 9500-1050 ℃).
16. The method of claim 15, wherein: the gasification agent sprayed into the kiln specifically comprises: during the rotation process of the rotary kiln (1), the gasifying agent is directly sprayed into the material through a gasifying agent nozzle (106) positioned below the material all the time; and/or
The injection of combustion-supporting gas into the kiln specifically comprises the following steps: in the rotation process of the rotary kiln (1), combustion-supporting gas is directly sprayed into a cavity above the material all the time through a combustion-supporting gas nozzle (107) above the material.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116753712A (en) * | 2023-08-21 | 2023-09-15 | 山西大地民基生态环境股份有限公司 | Mixed powder treatment device for recycling red mud |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116753712A (en) * | 2023-08-21 | 2023-09-15 | 山西大地民基生态环境股份有限公司 | Mixed powder treatment device for recycling red mud |
| CN116753712B (en) * | 2023-08-21 | 2023-10-20 | 山西大地民基生态环境股份有限公司 | Mixed powder treatment device for recycling red mud |
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