CN215799685U - Air-suspension type rotary kiln reactor - Google Patents
Air-suspension type rotary kiln reactor Download PDFInfo
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- CN215799685U CN215799685U CN202121353091.9U CN202121353091U CN215799685U CN 215799685 U CN215799685 U CN 215799685U CN 202121353091 U CN202121353091 U CN 202121353091U CN 215799685 U CN215799685 U CN 215799685U
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Abstract
The utility model provides an air-suspension type rotary kiln reactor, which comprises: the rotary kiln comprises a rotary kiln barrel, wherein the rotary kiln barrel comprises a main barrel body and reducing parts which are connected to two ends of the main barrel body and respectively shrink outwards, reducing ends of the reducing parts are connected with rotary shell sections, the rotary shell sections are connected with a sealing mechanism, and a sealing assembly is arranged at the joint of the sealing mechanism and the rotary shell sections; the inside of the main cylinder body is provided with a plurality of lifting components, so that the particle iron oxide can form a multi-layer material curtain when the rotary kiln cylinder body rotates, and the reducing gas can pass through the multi-layer material curtain and fully contact with the particle iron oxide. The sealing mechanism is connected to the rotary shell ring after necking, so that the mounting difficulty of the sealing assembly between the rotary shell ring and the sealing mechanism is reduced, the contact area of the granular iron oxide and the reducing gas is effectively increased by the formed multilayer material curtain, and the reaction can be fully and completely carried out.
Description
Technical Field
The utility model relates to the technical field of metallurgy, in particular to an air-suspension type rotary kiln reactor.
Background
The iron and steel smelting industry comprises a blast furnace iron-making technology and a non-blast furnace iron-making technology, the non-blast furnace iron-making technology is divided into direct reduction and smelting reduction, and the direct reduction comprises two forms of gas-based reduction and coal-based reduction. Coking and sintering in the blast furnace iron making process can discharge a large amount of dust, carbon dioxide and other gases, and bring great pressure to the environment.
In the non-blast furnace ironmaking technology, the gas-based reduction process reduces iron oxide in iron ore into metallized pellets by using reducing gas, has higher ironmaking efficiency than the traditional carbon reduction method, does not need coking and sintering, and has cleaner production process.
At present, the gas-based reduction technology mainly uses a Midrex gas-based shaft furnace technology and a HYL gas-based shaft furnace technology, iron ore and a binder are mixed and roasted to obtain oxidized pellets by using the gas-based shaft furnace, and then reduction is carried out at high temperature by using reducing gas, wherein the reducing gas mainly comes from synthetic gas obtained by steam conversion or reforming of natural gas, synthetic gas obtained by coal gasification, coke oven tail gas in coke industry and the like. Reducing gas in the Midrex gas-based shaft furnace enters the shaft furnace at 850-950 ℃, the reaction pressure is about 0.5MPa, and metallized pellets with the metallization rate of 92-93% can be obtained; the reducing gas of the HYL gas-based shaft furnace needs to be preheated to 900-2the/CO is 5.6-5.9, and the metallized pellet with the average metallization rate of 91-95 percent can be obtained.
Besides shaft furnace technology, gas-based reduction technology is also fluidized bed technology, the most representative of which are the FINMET technology and the H-IRON technology. FinFET is a representative technology of fluidized bed direct reduction, is also the only fluidized bed direct reduction process in production at present, is developed by the union of Otto and Venezuela FIORe company, and the main process adopts four-stage series fluidized beds to finally obtain a product with about 93 percent metallization rate, and the product is subjected to hot briquetting to obtain the final product. H-IRON technologyThe technology is a high-pressure low-temperature fluidized reduction technology, which is jointly developed by Hydro carbon Research Inc and Bethlehom Steel Conp, wherein the reducing gas contains 96 percent of hydrogen, a fluidized bed comprising three bed layers is adopted, mineral powder stays in the reducing bed for 45 hours, the bed layer is operated within the range of a bubbling bed at the operating gas speed, and the reduction degrees, H and H of 47 percent (first section), 87 percent (second section) and 98 percent (third section) are respectively obtained in each section2The conversion per pass is about 5 percent, the operation is interrupted, and no commercial device runs due to the economic benefit problem of the technology.
At present, the direct reduction technology adopts a shaft furnace technology for the most part, and adopts a coal-based direct reduction technology for a small amount so as to produce metal pellets with high metallization rate or hot-press the pellets into blocks as products. In the fluidized bed technology using iron powder as a product, only a few factories run due to the reasons of long retention time of iron ore powder, low utilization efficiency of reducing gas, low metallization rate of the product, fluidization caused by mutual adhesion of iron particles at high temperature, unstable running of the device, poor economic benefit and the like.
With the vigorous development of natural gas resources in China and the rapid development of new energy technologies and industries such as solar power generation, electrolytic hydrogen production and the like, the method for smelting steel by using natural gas or hydrogen is more and more feasible in cost and is beneficial to reducing the emission of carbon dioxide.
The rotary kiln is a common high-temperature device and is widely used in metallurgy, chemical industry, building refractory materials, environmental sanitation and other industries, and the conventional rotary kilns are divided into a cement rotary kiln, a lime rotary kiln and a metallurgical chemical rotary kiln. The rotary kiln can continuously turn over materials through the rotation of the barrel, the shoveling plates can be arranged on the barrel, the materials are strengthened to roll, a better mixing effect is achieved, and for a large-scale cement and lime rotary kiln, gas or pulverized coal can be sprayed in the kiln, so that the temperature in the kiln reaches thousands of degrees, and cement and lime in China are basically produced by adopting the rotary kiln.
Rotary kilns are also used in the metallurgical industry, where nearly 1/4 g of reduced iron is produced in coal-based rotary kilns with a production of tens of millions of tons per year in direct reduced iron production, e.g. CN1016618B discloses a method for producing direct reduced iron by direct reduction of iron oxide containing materials in rotary kilns, where the iron oxide containing materials are reduced to direct reduced iron using solid carbonaceous reducing agents.
In actual operation and operation, the coal-based rotary kiln for producing the direct reduced iron has some defects, such as low utilization rate of coal powder, separation of solid materials by magnetic separation, easy entry of impurities contained in coal into a direct reduced iron product, ring formation and production stop of a rotary kiln cylinder caused by iron powder bonding at high temperature, gas leakage caused by poor sealing of equipment and the like.
The diameter of the existing large-scale rotary kiln reaches more than 5m, the sealing is difficult due to the overlarge diameter, most rotary kilns are operated under the condition of micro negative pressure, and the danger coefficient is undoubtedly increased for the production working condition of the direct reduced iron with reducing atmosphere.
SUMMERY OF THE UTILITY MODEL
The utility model aims to provide an empty suspension type rotary kiln reactor, which can enable granular iron oxide to form an empty suspension type material curtain in the rotary kiln reactor, can be fully contacted with reducing gas to be uniformly mixed, and reduces the difficulty of system sealing by arranging reducing forms at two ends of a rotary kiln.
The utility model also aims to provide a reaction method based on the air-suspension rotary kiln reactor, which directly obtains granular direct reduced iron by reducing granular iron oxide with reducing gas, effectively improves the reaction efficiency and ensures the metallization rate of the direct reduced iron powder.
The utility model provides an air-suspension type rotary kiln reactor, which comprises: the rotary kiln comprises a rotary kiln barrel, wherein the rotary kiln barrel comprises a main barrel and a variable-diameter part connected to two ends of the main barrel and gradually contracted outwards respectively, the contracted ends of the variable-diameter part are connected with rotary shell sections, the rotary shell sections are connected with a sealing mechanism, and a sealing assembly is arranged at the joint of the sealing mechanism and the rotary shell sections;
the inside of the main cylinder body is provided with a plurality of lifting components, so that the particle iron oxide can form a multi-layer material curtain when the rotary kiln cylinder body rotates, and the reducing gas can pass through the multi-layer material curtain and fully contact with the particle iron oxide.
Further, the sealing mechanism is arranged on the radial outer side of the rotary shell ring, and at least one part of the rotary shell ring extends into the sealing mechanism.
Furthermore, the sealing mechanism comprises a sealing cylinder section, an expansion joint and a sealing head, and the sealing assembly is arranged at the joint of the sealing cylinder section and the rotary cylinder section.
Furthermore, a cooling water inlet and a cooling water outlet are arranged on the sealing assembly.
Further, the rotary shell ring comprises a kiln head rotary shell ring and a kiln tail rotary shell ring, the sealing mechanism comprises a kiln head sealing mechanism and a kiln tail sealing mechanism, and a cooling gas inlet is formed in the kiln head sealing mechanism.
Further, kiln head closing mechanism includes kiln head closed shell ring, kiln head expansion joint and kiln head, kiln tail closing mechanism includes kiln tail closed shell ring, kiln tail expansion joint and kiln tail head, be connected with the intake pipe that is used for admitting air on the kiln head, be connected with the outlet duct that is used for exhausting on the kiln tail head.
Furthermore, at least one part of the air inlet pipe extends into the rotary shell ring of the kiln head, and at least one part of the air outlet pipe extends into the rotary kiln cylinder.
Further, a feeding screw for feeding is arranged in the kiln tail sealing mechanism, and a locking feeding hopper for sealed feeding is arranged at the upper part of the feeding screw.
Further, the inside ejection of compact spiral that is used for the ejection of compact that is provided with of kiln head closing mechanism, the bottom of kiln head is provided with the discharge gate, the discharge gate is connected with the shutting ejection of compact hopper that is used for airtight ejection of compact.
Furthermore, a material baffle plate is arranged between the kiln head closed shell ring and the kiln head rotary shell ring.
Further, the reducing part comprises a kiln head reducing part, and a kiln head reducing guide plate and a kiln head guide plate for guiding out materials are respectively arranged inside the kiln head reducing part and the kiln head rotary cylinder section.
Furthermore, the kiln head reducing guide plate is obliquely arranged towards the rotation direction of the rotary kiln cylinder.
Furthermore, the kiln head guide plate is arranged at the joint of the kiln head rotary cylinder section and the kiln head reducing diameter.
Furthermore, a main cylinder guide plate is connected inside the main cylinder, and the main cylinder guide plate is arranged on one side, where the main cylinder is located, of the kiln head with variable diameter.
Further, the kiln head guide plate and the main cylinder guide plate are respectively arranged in the radial direction of the kiln head rotary cylinder section and the main cylinder in an inclined mode.
Further, the diameter-variable part also comprises a kiln tail reducing part, and a kiln tail reducing guide plate for guiding materials is arranged in the kiln tail reducing part.
Furthermore, the lifting components comprise a plurality of sections which are uniformly distributed at intervals along the axial direction of the main cylinder body, and the lifting components of each section are uniformly distributed at intervals along the radial direction of the main cylinder body.
Furthermore, the plurality of sections of the lifting components are arranged in a staggered mode along the axial direction of the main cylinder body.
Furthermore, each lifting component comprises a lifting plate and a lifting plate, one end of the lifting plate is connected to the inner wall of the main cylinder, and the other end of the lifting plate is connected with the lifting plate.
Further, the shovelling plates extend along the radial direction of the main cylinder.
Further, the ratio of the length of the shoveling plate to the diameter of the main cylinder is 1:20-1: 3.
Further, the lifting plate is of a semicircular bent plate structure, and the ratio of the radius of the lifting plate to the length of the shoveling plate is 1:10-1: 2.
Further, the width of the shovelling plate is the same as that of the lifting plate.
A reaction method adopting the air-suspension rotary kiln reactor is used for directly obtaining granular direct reduced iron by reducing granular iron oxide with reducing gas, and comprises the following steps:
(1) preheating the granular iron oxide and reducing gas respectively;
(2) the granular iron oxide forms a multi-layer material curtain through the lifting component, and is in full reverse contact reaction with reducing gas passing through the multi-layer material curtain, so that granular direct reduced iron is obtained through reduction.
Further, the preheating temperature of the granular iron oxide is 500-750 ℃, and the preheating temperature of the reducing gas is 450-650 ℃.
Further, the operating pressure of the suspended rotary kiln reactor is 0.01-3MPa, preferably 0.05-2.5MPa, and more preferably 0.1-2 MPa.
Further, the residence time of the granular iron oxide in the suspended rotary kiln reactor is 1-15h, preferably 2-10h, and more preferably 3-8 h.
Further, the average particle diameter of the particulate iron oxide is 0.015 to 4mm, preferably 0.05 to 2mm, more preferably 0.1 to 1 mm.
Further, reducing H in the gas in terms of volume fraction2Content (wt.)>50％，CO2Content (wt.)<3％。
Further, reducing H in the gas in terms of volume fraction275-100% of CO, 0-10% of CO2The content is 0-1%.
The utility model has the following beneficial effects: the two ends of the main cylinder body are respectively connected with the diameter-variable parts which gradually shrink outwards, and the rotary cylinder section with the reduced size is connected with the sealing mechanism, so that the mounting difficulty of the sealing assembly between the rotary cylinder section and the sealing mechanism is reduced, and the sealing performance of the air-suspension rotary kiln reactor is effectively ensured. Meanwhile, the reducing rotary cylinder section and the main cylinder body form a calabash-like opening structure, so that the thickness of the material at the bottom of the rotary kiln is effectively and greatly improved, the solid material loading amount is increased, and the production capacity of the equipment is increased.
Through a plurality of lifting components arranged in the main cylinder, a plurality of material curtains can be formed in the main cylinder when the granular iron oxide rotates in the rotary kiln cylinder, so that the granular iron oxide is uniformly distributed in the rotary kiln cylinder, and an air-suspension type material distribution mode in the rotary kiln reactor is formed.
The reducing gas passes through the multiple layers of material curtains in the rotary kiln barrel and can be fully contacted with the evenly distributed granular iron oxide, so that the material distribution working condition of the granular iron oxide is improved.
The contact area of the granular iron oxide and the reducing gas is effectively increased through the multilayer material curtains formed in the main cylinder body, and the reaction can be fully and completely carried out.
The reaction method of the hollow suspension type rotary kiln reactor can lead the granular iron oxide and the reducing gas to oppositely move reversely, lead the reducing gas to pass through the multi-layer material curtain of the granular iron oxide, and directly carry out reduction reaction in the contact of the reducing gas and the granular iron oxide, thereby achieving the technical purpose of directly obtaining granular directly reduced iron by reducing the granular iron oxide by using the reducing gas.
The air-suspension type rotary kiln reactor and the reaction method do not need to ball iron ore powder, introduce reducing agents such as coal powder and the like which are easy to bring impurities, and do not need to additionally arrange complicated components such as a combustion nozzle and the like.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
FIG. 1 is a schematic structural view of an air-suspension rotary kiln reactor according to the present invention;
FIG. 2 is a schematic sectional view of the head and tail of the kiln of the present invention;
FIG. 3 is a schematic structural view of a kiln head reducing guide plate according to the present invention;
FIG. 4 is a schematic structural view of a kiln head guide plate according to the present invention;
FIG. 5 is a schematic structural view of a main cylinder baffle in the present invention;
FIG. 6 is a distribution state diagram of the shoveling and raising components in the main cylinder;
FIG. 7 is a schematic structural diagram of a shoveling and raising assembly according to the present invention;
FIG. 8 is a schematic view showing the state of the materials in the rotary kiln during rotation.
In the figure:
1-roller support; 2-main cylinder; 3-reducing the kiln head; 4-locking the discharge hopper; 5-kiln head sealing assembly; 6-expansion joint of kiln head; 7-discharging port; 8-discharging spiral; 9-an air inlet pipe; 10-sealing a kiln head; 11-kiln head rotary shell ring; 12-reducing the kiln tail; 13-kiln tail rotary shell ring; 14-kiln tail seal assembly; 15-kiln tail expansion joint; 16-kiln tail end sealing; 17-an air outlet pipe; 18-a lock feed hopper; 19-a feed screw; 20-a base; 21-a transmission; 22-kiln head closed shell ring; 23-kiln tail closed shell ring; 31-a striker plate; 32-cooling gas inlet; 33-main cylinder flow guide plate; 34-a kiln head reducing guide plate; 35-kiln head guide plate; 36-cooling water outlet; 37-cooling water inlet; 38-discharge screw shaft; 39-a discharge drive; 40-a discharge spiral pipe; 41-a feed drive; 42-feed screw axis; 43-a feed coil; 44-outlet pipe orifice; 45-kiln tail reducing guide plate; 51-shovelling plates; 52-flying board.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the utility model, as claimed, but is merely representative of selected embodiments of the utility model. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings or orientations or positional relationships that the products of the present invention are conventionally placed in use, and are only for convenience of describing the present invention and simplifying the description, but do not indicate or imply that the device or element to which the description refers must have a specific orientation, be constructed in a specific orientation, and be operated, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," and the like are used solely to distinguish one from another and are not to be construed as indicating or implying relative importance.
Furthermore, the terms "horizontal", "vertical", "overhang" and the like do not imply that the components are required to be absolutely horizontal or overhang, but may be slightly inclined. For example, "horizontal" merely means that the direction is more horizontal than "vertical" and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.
In the description of the present invention, it should also be noted that, unless otherwise explicitly specified or limited, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Some embodiments of the utility model are described in detail below with reference to the accompanying drawings. The embodiments described below and the features of the embodiments can be combined with each other without conflict.
Referring to fig. 1-2, the present invention provides an air-suspension rotary kiln reactor, which includes: the rotary kiln comprises a rotary kiln barrel, wherein the rotary kiln barrel comprises a main barrel body 2 and a variable-diameter part connected to two ends of the main barrel body 2 and gradually contracted outwards respectively, the contracted ends of the variable-diameter part are connected with rotary shell sections, the rotary shell sections are connected with a sealing mechanism, and a sealing assembly is arranged at the joint of the sealing mechanism and the rotary shell sections;
the inside of the main cylinder body 2 is provided with a plurality of lifting components, so that the particle iron oxide can form a multi-layer material curtain when the rotary kiln cylinder body rotates, and the reducing gas can pass through the multi-layer material curtain and fully contact with the particle iron oxide.
The suspended rotary kiln reactor mainly performs reduction reaction of granular iron oxide, the sizes of two ends of the rotary kiln can be reduced by connecting the variable-diameter parts which gradually shrink outwards respectively at two ends of the main cylinder body 2, the overall size of a sealing assembly between the rotary cylinder section and the sealing mechanism can be reduced by connecting the sealing mechanism on the rotary cylinder section with the reduced size, the installation difficulty of the sealing assembly is greatly reduced, the overall sealing performance of the suspended rotary kiln reactor is reliably ensured, and the safety and reliability of reducing gas as a reducing agent are effectively improved.
Through the subassembly of lifting by shoveling a plurality of that set up in main barrel 2 inside, the rotary kiln barrel makes granule iron oxide can form the cloth form of multilayer material curtain when rotating, through the multilayer material curtain that forms, can make granule iron oxide at 2 inside evenly distributed of main barrel, and the reducing gas who passes in multilayer material curtain can fully contact with granule iron oxide to carry out reduction reaction in the contact, effectively improved reaction efficiency when guaranteeing gas-solid area of contact.
In the air-suspension type rotary kiln reactor, granular iron oxide enters a reaction system from the kiln tail, gradually moves towards the kiln head in the form of a multi-layer material curtain when a rotary kiln cylinder rotates, is converted into granular direct reduced iron after being continuously contacted and reduced with reducing gas, and is finally discharged out of the system from the kiln head.
The reducing gas enters the reaction system from the kiln head and is discharged from the kiln tail after passing through the multiple layers of material curtains, and the reducing gas is fully contacted with the material curtain formed by the granular iron oxide in the passing process to carry out reduction reaction on the granular iron oxide, so that the reverse contact between the granular iron oxide and the reducing gas is effectively formed, and the reaction condition in the rotary kiln is greatly improved.
The sealing mechanism is arranged on the radial outer side of the rotary shell ring, at least one part of the rotary shell ring extends into the sealing mechanism, and the sealing mechanism and one part of the rotary shell ring can be overlapped in a crossing mode through the arrangement mode, so that an annular gap is formed between the sealing mechanism and the rotary shell ring, and the installation of the sealing assembly is facilitated.
In one embodiment, the sealing mechanism specifically comprises a sealing cylinder section, an expansion joint and a sealing head which are sequentially connected from outside to inside, the sealing cylinder section is specifically a straight pipe type short section, and the sealing assembly is arranged at the joint of the sealing cylinder section and the rotary cylinder section. The rotary kiln cylinder is in a rotating state in the operation process, the rotating assembly is specifically composed of the main cylinder 2, the reducing part and the rotary cylinder section, the sealing assembly arranged between the rotary cylinder section and the closed cylinder section is specifically a dynamic sealing structure, and the forms of axial flow sealing or mechanical sealing and the like can be selected.
Based on the high-temperature reaction condition of the air-suspension rotary kiln reactor, the expansion joint included by the sealing mechanism can release and offset the thermal deformation generated in the operation process of the equipment, thereby being beneficial to buffering the stress generated when the equipment is heated and ensuring the reliable operation of the equipment.
Seal assembly in this embodiment includes kiln head seal assembly 5 and kiln tail seal assembly 14, in order to reduce seal assembly at the temperature of operation in-process, adopt the water-cooling form to cool down seal assembly in this embodiment, all be provided with cooling water inlet 37 and cooling water outlet 36 on kiln head seal assembly 5 and kiln tail seal assembly 14, equipment operation is cooled down seal assembly through the form of leading in recirculated cooling water from the outside at cooling water inlet 37 and cooling water outlet 36, seal assembly temperature in service has effectively been reduced, service life has been prolonged.
Besides cooling the kiln head sealing assembly 5 in a water cooling mode, the kiln head sealing assembly 5 is cooled in a cooling gas introducing mode. Specifically, the rotary shell ring comprises a kiln head rotary shell ring 11 and a kiln tail rotary shell ring 13, the sealing mechanism comprises a kiln head sealing mechanism and a kiln tail sealing mechanism which correspond to the kiln head rotary shell ring 11 and the kiln tail rotary shell ring 13, and the kiln head sealing mechanism is connected with a cooling gas inlet 32.
Through set up cooling gas import 32 on kiln hood closing mechanism to connect the cooling gas pipeline through cooling gas import 32, can cool off the ejection of compact of kiln hood position on the one hand, on the other hand can cool off seal assembly when the circulating water is interrupted.
According to the utility model, under the reaction condition that the reducing gas is filled into the air-suspension rotary kiln reactor, the reducing gas is preferably inert gas such as nitrogen, the sealing assembly is cooled, and the reaction system can be well protected, so that the space of the kiln head is in the inert atmosphere, and the re-oxidation of the reduced iron particles during discharging is prevented.
In another embodiment, the kiln head sealing mechanism comprises a kiln head sealing cylinder section 22, a kiln head expansion joint 6 and a kiln head end enclosure 10, the kiln tail sealing mechanism comprises a kiln tail sealing cylinder section 23, a kiln tail expansion joint 15 and a kiln tail end enclosure 16, an air inlet pipe 9 for air inlet is connected to the kiln head end enclosure 10, and an air outlet pipe 17 for air exhaust is connected to the kiln tail end enclosure 16.
The reducing gas can enter the reaction system from the kiln head part and move to the kiln tail along the axial direction of the rotary kiln cylinder body through the gas inlet pipe 9 on the kiln head end enclosure 10 and the gas outlet pipe 17 on the kiln tail end enclosure 16, and the reacted reducing gas is discharged from the kiln tail part out of the reaction system.
The reduction reaction of the granular iron oxide in the hollow rotary kiln reactor is mainly carried out in a rotary kiln cylinder, in order to enable the reducing gas to directly enter the rotary kiln cylinder, at least one part of the tail end of the air inlet pipe 9 extends into a kiln head rotary cylinder section 11 included in the rotary kiln cylinder, and simultaneously in order to reduce the aggregation of the reducing gas at the kiln tail part, at least one part of the air outlet pipe 17 extends into the rotary kiln cylinder, specifically, the end part of the air outlet pipe 17 in the rotary kiln cylinder, namely an air outlet pipe opening 44, is arranged in a kiln tail reducing pipe 12 positioned at the kiln tail, the reducing gas after the reaction can be discharged from the system after passing through the main cylinder 2 through the arrangement mode, so that the aggregation amount of the reducing gas after the reaction in the reaction system is reduced, and the reduction reaction of the granular iron oxide is carried out more fully.
The granular iron oxide in the utility model is in reverse contact with the reducing gas in the rotary kiln barrel, and is a granular sponge body which is fed at the kiln tail and discharged from the kiln head after reduction based on the flow direction of the reducing gas from the kiln head to the kiln tail.
Specifically, a feeding screw 19 for feeding is arranged inside the kiln tail closing mechanism, and a locking feeding hopper 18 for closed feeding is arranged at the upper part of the feeding screw 19. The feed screw 19 comprises a feed screw shaft 42 for conveying the particulate iron oxide, and the discharge outlet of the lock feed hopper 18 is disposed above the feed screw shaft 42.
The inside ejection of compact spiral 8 that is used for the ejection of compact that is provided with of kiln head closing mechanism, the bottom of kiln head 10 is provided with discharge gate 7, and ejection of compact spiral 8 is including the ejection of compact screw axis 38 that is used for carrying granule direct reduced iron after the reduction, and ejection of compact screw axis 38 erects directly over discharge gate 7, and the granule cavernosum after the reduction of being convenient for is connected with the shutting ejection of compact hopper 4 that is used for airtight ejection of compact on discharge gate 7 at discharge gate 7 position blanking after ejection of compact spiral 8's the transport.
The feeding screw 19 and the discharging screw 8 in this embodiment are both used for conveying solid materials, and based on a closed reaction system, the feeding screw 19 and the discharging screw 8 are respectively connected with the kiln tail end socket 16 and the kiln head end socket 10 in a sealing manner, and respectively comprise a feeding spiral tube 43 and a discharging spiral tube 40 for accommodating the spiral shafts.
In the kiln tail part, the feeding spiral pipe 43 and the feeding spiral shaft 42 simultaneously extend into the kiln tail end socket 16 and the kiln tail rotary cylinder section 13, and the extending tail end enters the kiln tail reducing diameter 12, so that the granular iron oxide can directly enter the rotary kiln cylinder through the feeding spiral pipe 43 and the feeding spiral shaft 42, on one hand, the scattering of solid materials at the kiln tail part can be reduced, on the other hand, the feeding can be directly subjected to reduction reaction in the reducing atmosphere in the rotary kiln cylinder, and the reaction sufficiency is effectively guaranteed.
The discharging spiral pipe 40 does not extend into the kiln head end socket 10, and is externally connected with the kiln head end socket 10, so that the extending tail end of the discharging spiral pipe 38 extends into the kiln head rotary cylinder section 11, and the discharging spiral pipe 38 can effectively pour reduced granular direct reduced iron through the arrangement mode, and the pouring stroke of the granular direct reduced iron is reduced, so that the granular direct reduced iron enters the locking discharging hopper 4 from the discharging port 7 as soon as possible, and the risk of secondary oxidation is reduced.
The feeding driving device 41 and the discharging driving device 39 for driving the feeding screw shaft 42 and the discharging screw shaft 38 are connected to the outside of the feeding spiral pipe 43 and the discharging spiral pipe 40, so that the electrical equipment is isolated from the reaction system of the reducing atmosphere, and the safety risk is further avoided.
Through the locking feeding hopper 18 and the locking discharging hopper 4 in the embodiment, the whole tightness of the suspended rotary kiln reactor is ensured, and external air is prevented from entering the reaction system, so that the whole safety of the reaction system is guaranteed.
From the angle of kiln head ejection of compact, in order to reduce partial ejection of compact entering kiln head expansion joint 6 and kiln head seal assembly 5, still be provided with striker plate 31 between kiln head closed shell ring section 22 and kiln head rotary shell ring section 11, this striker plate 31 specifically sets up the outer end lower part at kiln head rotary shell ring section 11, the semicircular ring structure that can set up for the slope, baffle through semicircular ring structure can prevent that granule direct reduction iron from getting into the gap between kiln head rotary shell ring section 11 and the kiln head seal shell ring section at the in-process from ejection of compact screw axis 38 blanking to discharge gate 7, and then direct influence expansion joint and seal assembly's normal use.
In a preferred embodiment, a flow guide plate structure is arranged at the kiln head position from the angle of facilitating discharging. A kiln head reducing guide plate 34 and a kiln head guide plate 35 for guiding materials are respectively arranged in the kiln head reducing 3 and the kiln head rotary cylinder section 11 which are positioned at the kiln head part.
Referring to fig. 3, a structure of one of the kiln head reducing guide plates 34 on the kiln head reducing end 3 is shown, the kiln head reducing guide plate 34 is arranged in an inclined manner towards the rotation direction of the rotary kiln cylinder, specifically, a part of the kiln head reducing guide plate 34, which is far away from the main cylinder 2, i.e. is close to the neck end of the kiln head reducing end 3, is provided with a certain inclination angle towards the rotation direction, and a part of the kiln head reducing guide plate 34, which is close to the expansion end of the kiln head reducing end 3, is inclined towards the rotation direction. The kiln head reducing guide plate 34 which is obliquely arranged can effectively play a role in guiding flow, so that the discharging can be smoother.
The kiln head reducing guide plate 34 in this embodiment includes a plurality of guide plates uniformly distributed on the kiln head reducing 3 at intervals, and the guide plates are uniformly distributed in the circumferential direction of the kiln head reducing 3 to form a discharge guide plate spirally distributed on the kiln head reducing 3. Through the kiln head reducing guide plate 34 which is distributed spirally, the granular direct reduced iron can form a scattered distribution state during discharging, the adhesion of the granular direct reduced iron is prevented, and the quality of the product is improved.
Referring to fig. 4, a kiln head guide plate 35 arranged in the kiln head rotary shell ring 11 is arranged at the connecting position of the kiln head rotary shell ring 11 and the kiln head reducing guide plate 3, and the kiln head guide plate 35 and the kiln head reducing guide plate 34 are in a connecting state, so that discharging of materials poured from the kiln head reducing guide plate 3 and entering the kiln head rotary shell ring 11 can be effectively carried out, and a continuous discharging state is formed.
Referring to fig. 5, a main cylinder guide plate 33 is further connected inside the main cylinder 2, the main cylinder guide plate 33 is specifically arranged on one side of the main cylinder 2, which is located at the kiln head reducing diameter 3, the main cylinder guide plate 33 is also connected with the kiln head reducing guide plate 34, and the kiln head guide plate 35 and the main cylinder guide plate 33 also include a plurality of guide plates which are uniformly distributed at intervals on the kiln head rotary cylinder section 11 and the main cylinder 2 in the circumferential direction.
Kiln head guide plate 35 and main barrel guide plate 33 slope respectively and set up in the radial direction of kiln head gyration shell ring 11 and main barrel 2, compare the setting mode that the level was laid, and the kiln head guide plate 35 and the main barrel guide plate 33 that slope can make the ejection of compact at the kiln head position form fixed flow direction, improve ejection of compact efficiency.
The guide plates of the three sections of the guide plates of the main cylinder body 33, the kiln head reducing guide plate 34 and the kiln head guide plate 35 can be connected in sequence, and meanwhile, the guide plates of the sections can also be arranged in a staggered mode in the radial direction of the rotary kiln cylinder body.
The smooth and easy nature of the ejection of compact can be guaranteed to the three-section guide plate that meets in proper order, and staggered arrangement's three-section guide plate then enables the ejection of compact more dispersion, can adjust according to the operating condition demand when specifically setting up, and it is no longer repeated here.
In order to further improve the smooth degree of discharging, shorten the discharging stroke and avoid secondary oxidation, the extending tail end of the discharging screw shaft 38 is close to the kiln head guide plate 35, so that the discharging screw shaft 38 can directly receive the materials led out from the kiln head guide plate 35.
From the angle to feeding homodisperse in rotary kiln barrel inside, be provided with kiln tail reducing guide plate 45 that is used for leading-in material in kiln tail reducing 12 inside, kiln tail reducing guide plate 45 interval equipartition is in the circumference of kiln tail reducing 12, can constitute the preliminary dispersion of feeding, does benefit to the area of contact of increase granule iron oxide and reducing gas.
In another preferred embodiment, the lifting assemblies arranged inside the main cylinder 2 comprise a plurality of sections which are uniformly distributed at intervals along the axial direction of the main cylinder 2, and each section of the lifting assembly is uniformly distributed at intervals in the radial direction of the main cylinder 2.
Referring to fig. 7 to 8, the shoveling and raising assembly in the present embodiment specifically includes a shoveling plate 51 and a raising plate 52, the shoveling plate 51 is a flat plate structure, one end of the shoveling plate 51 is connected to the inner wall of the main cylinder 2, the other end of the shoveling plate is connected to the raising plate 52, and the shoveling plate 51 extends along the radial direction of the main cylinder 2.
The lifting plate 52 is a semicircular bent plate structure, and is connected to the extending tail end of the lifting plate 51 towards the axle center of the main cylinder 2, and the opening direction formed between the lifting plate 51 and the lifting plate 52 is the same as the rotation direction of the cylinder of the rotary kiln.
When the rotary kiln cylinder rotates, the shoveling plate 51 on one shoveling and lifting assembly can shovel and stop solid materials gathered at the bottom of the rotary kiln cylinder, and meanwhile, part of the materials can enter an opening space on the shoveling plate 52 in a rolling manner along the inner part of the main cylinder 2 during the rotation of the rotary kiln cylinder. When the shoveling plate 51 and the lifting plate 52 for blocking and carrying the solid materials rotate to the middle position of the main cylinder 2, the materials are scattered, and when the shoveling plate 51 and the lifting plate 52 rotate to the bottom of the main cylinder 2, the whole material scattering process is completed immediately. Through a plurality of shoveling and lifting components uniformly distributed in the circumferential direction of the main cylinder body 2, bulk cargo areas formed by a plurality of independent shoveling and lifting components can be collected to form a relatively complete bulk cargo surface, so that a distribution form of a particle iron oxide material curtain is formed.
Through the subassembly of lifting by shoveling of multistage distribution, can effectively constitute solid material along 2 ascending multilayer material curtains of main cylinder body axial, greatly increase solid material's dispersion area, simultaneously through contacting with the reduction gas that walks in multilayer material curtain, improved the contact condition of solid material and gaseous material from the at utmost, greatly promoted granular iron oxide's reduction reaction efficiency.
Referring to fig. 6, in order to further improve the distribution state of the solid material, the multi-section shoveling and raising assemblies are arranged in a staggered manner along the axial direction of the main cylinder 2, and a stacked state in which the material is distributed in a staggered manner in the radial direction of the main cylinder 2 can be formed by the staggered multi-section shoveling and raising assemblies, so that uniform dispersion of the granular iron oxide in the cylinder of the rotary kiln is facilitated.
Each lifting component is uniformly distributed along the radial direction of the main cylinder 2 at intervals of D, each lifting component and the adjacent lifting component are moved along the radial translation width D of the main cylinder 2 along the axial translation height H of the main cylinder 2, and D is 1/5D and H is 1/2D.
The ratio of the length of the shovelling plate 51 to the diameter of the main cylinder 2 is 1:20-1:3, the ratio of the radius of the shovelling plate 51 to the length of the shovelling plate 51 is 1:10-1:2, the ratio of the length of the shovelling plate 51 to the diameter of the main cylinder 2 in the embodiment is preferably 1:10, the ratio of the radius R of the lifting plate 52 to the length L of the shovelling plate 51 is preferably 1:2, and the specific sizes of the shovelling plate 51 and the lifting plate 52 can be set according to the specific size of the main cylinder 2 and the actual use condition.
From the angle of the material blocking amount of the lifting component to the solid materials, the width of the lifting plate 51 is the same as that of the lifting plate 52, so that the materials can be effectively contained, and the stable and reliable material curtain is guaranteed.
The rotary kiln cylinder body is arranged on a base 20, a transmission device 21 is arranged in the middle of the rotary kiln cylinder body, and the transmission device 21 is driven by a motor to rotate so as to drive the rotary kiln cylinder body to rotate. The roller supports 1 are arranged on two sides of the rotary kiln barrel, and the roller supports 1 are arranged on the base 20, so that the rotary kiln barrel can be supported when rotating, and the reliable operation of the whole equipment is guaranteed.
It is important to point out that the solid materials can be distributed in a rain curtain type through the special lifting component and the blanking form of the materials in the rotary kiln cylinder body, the reducing gas continuously passes through the solid materials distributed in the rain curtain type when passing through the reaction system, and the gas-solid contact is more sufficient.
The two ends of the main cylinder body 2 of the rotary kiln are connected with the reducing pipe, and the kiln head and the kiln tail after necking can adopt a high-pressure water-cooling sealing structure, so that a reaction system can be operated under positive pressure, the leakage risk is greatly reduced, and the reaction efficiency is improved.
According to the utility model, the heat-insulating layer can be arranged on the outer side of the rotary kiln cylinder of the air-suspension type rotary kiln reactor, or the heat-insulating layer is arranged on the inner wall of the rotary kiln cylinder, so that the heat-insulating property of the rotary kiln reactor is enhanced, and the heat loss is reduced. Meanwhile, the inner wall of the rotary kiln cylinder body can be provided with a structure of a heat-insulating layer and a wear-resistant layer so as to reduce the erosion of the cylinder body by the granular iron oxide and prolong the service life of the equipment.
Along the axial direction of the rotary kiln reactor, a plurality of temperature and pressure measuring interfaces for detecting temperature and pressure, manholes and hand holes for maintenance are distributed, so that the normal operation of equipment is met.
The utility model also provides a reaction method adopting the air-suspension rotary kiln reactor, which is used for directly obtaining the granular directly reduced iron by reducing the granular iron oxide with reducing gas and comprises the following steps:
1) adding preheated granular iron oxide and adding preheated reducing gas at the same time;
2) the granular iron oxide forms a multi-layer material curtain through the lifting component, and is fully in reverse contact reaction with reducing gas passing through the multi-layer material curtain, so that granular direct reduced iron is obtained through reduction;
3) and discharging the reacted reducing gas from the reaction system, and reducing the granular iron oxide to obtain granular directly reduced iron.
Specifically, in the reaction process, firstly, a transmission device 21 is driven by a motor to enable a rotary kiln cylinder to do circular motion, the granular iron oxide preheated to 500-;
while adding the granular iron oxide, continuously adding reducing gas preheated to 450-650 ℃ into a reaction system from an air inlet pipe 9 positioned at the top of the kiln head, enabling the reducing gas to flow to the kiln tail along the axial direction of the rotary kiln cylinder, contacting with the spread solid material in the flowing process, and finally flowing out of the reaction system from an air outlet pipe 17 at the kiln tail, and reducing the iron oxide in the solid into granular directly reduced iron in the contact of the reducing gas and the solid material.
The range of the internal operating pressure of the suspended rotary kiln reactor is 0.01-3MPa, and under the operating pressure, the reaction of the granular iron oxide and the reducing gas can be ensured to be more fully carried out. The operating pressure may preferably be 0.05 to 2.5MPa, more preferably 0.1 to 2MPa, and may be selected from 0.01MPa, 0.05MPa, 0.1MPa, 2MPa, 2.5MPa and 3MPa, and may further be 0.03MPa, 0.08MPa, 0.5MPa, 1.2MPa, 1.5MPa, 2.4MPa, 2.6MPa and 2.8 MPa.
In order to ensure that the granular iron oxide can react more fully in the suspended rotary kiln reactor, the granular iron oxide needs to have sufficient residence time in the suspended rotary kiln reactor, and the residence time of the granular iron oxide in the suspended rotary kiln reactor in the embodiment is in the range of 1-15h, preferably 2-10h, and more preferably 3-8 h. The time can be selected from 1h, 2h, 3h, 5h, 8h, 10h and 15h, and can also be selected from 1.5h, 2.5h, 3.5h, 4h, 6h, 12h, 14h and the like.
The average particle size of the particulate iron oxide needs to satisfy certain requirements in view of the reduction reaction with the reducing gas, and in this embodiment the average particle size of the particulate iron oxide is 0.015 to 4mm, preferably 0.05 to 2mm, and more preferably 0.1 to 1 mm. The thickness of the film may be selected from 0.015mm, 0.05 mm, 0.1mm, 0.5mm, 1mm, 2mm, 3mm and 4mm, and may be further selected from 0.04mm, 0.08mm, 0.15mm, 0.3mm, 0.4mm, 0.8mm, 1.5mm, 2.5mm, 2.8mm and 3.5 mm.
The reducing component of the reducing gas needs to meet the basic reduction requirements in this example based on the reduction reaction performed on the particulate iron oxide. In this example, the gas component of the reducing gas was, in terms of volume fraction, H in the reducing gas2Content (wt.)>50％，CO2Content (wt.)<3％。
Except for H in the reducing gas2When special requirements on the carbon component in the granular direct reduced iron are required, part of the carbon-based reducing component needs to be introduced into the reducing gas, and the carbon-based reducing component in the reducing gas in the embodiment is CO.
The reducing gas composition is more suitable for gas phase reduction of iron in the air suspension type rotary kiln reactor, wherein the content of CO can be changed according to requirements, and if the direct reduced iron has higher carbon content, the content of CO can be properly increased.
Preferably, the gas component of the reducing gas, in volume fraction, is H in the reducing gas2In an amount of75-100%, CO content of 0-10%, CO2The content is 0-1%. H2The content can be 75%, 80%, 85%, 88%, 90%, 95%, 99%, 100%, etc., and the content of CO can be 0.5%, 1%, 2%, 3%, 4%, 6%, 8%, 9%, 9.5%, etc., in terms of volume fraction, according to the change of the carbon content of the direct reduced iron, and the content of CO can be adjusted according to the quality requirements of the specific production of the direct reduced iron. In the composition of reducing gas, CH can also be added4、CO2And N2Equal gas composition, but from the standpoint of facilitating reduction, CO2The content should be controlled at a low level, in volume fraction, of CO2The content is controlled to be 1% or less, and may be 0.2%, 0.3%, 0.5%, 0.6%, 0.8%, or the like.
According to the reaction method disclosed by the utility model, the granular iron oxide and the reducing gas are respectively preheated and then added into the reaction system, and complex components such as a combustion nozzle are not required to be arranged, so that the equipment is simplified, the granular iron oxide and the reducing gas can be fully contacted and reacted, the reaction efficiency is greatly improved, and high-quality granular directly-reduced iron products can be reliably obtained.
The reaction method of the present invention will be described below with reference to different experimental examples and comparative examples based on the air-suspension rotary kiln reactor of the present invention.
Experimental example 1
The particle iron oxide with the particle size distribution of 5-40 meshes (380-4000 mu m and the average particle size of 1.05mm) has the chemical composition of total iron, FeO and SiO2、CaO、MgO、Al2O3MnO content of 55.2%, 0.29%, 8.69%, 0.01%, 6.53% and 0.07% respectively, preheating granular iron oxide to 750 deg.C, continuously adding into an air-suspension rotary kiln reactor, and reducing gas composition is H288% of CO, 0.5% of CO2Content 0.3%, CH4Content 2.5%, N2The content is 8.7 percent, reducing gas is preheated to 500 ℃ and is introduced into an air-suspension type rotary kiln reactor, the operating pressure of the air-suspension type rotary kiln reactor is 0.6MPa, the retention time of the granular iron oxide in the air-suspension type rotary kiln reactor is 5 hours, and finally the iron oxide can be obtainedThe direct reduced iron powder with the metallization rate of 96.7 percent and the carbon content of 0.2 percent is obtained.
Experimental example 2
The particle iron oxide with the particle size distribution of 10-40 meshes (380-1700 mu m and the average particle size of 0.78mm) has the chemical composition of total iron, FeO and SiO2、Al2O3The MnO content is 57.76%, 0.71%, 6.82%, 6.26% and 1.2%, the granular iron oxide is preheated to 700 deg.C, then continuously added into the air-suspension rotary kiln reactor, and the reducing gas composition is H2The content is more than 99 percent, reducing gas is preheated to 570 ℃ and is introduced into an air-suspension rotary kiln reactor, the operating pressure of the air-suspension rotary kiln reactor is 0.8MPa, the retention time of the granular iron oxide in the air-suspension rotary kiln reactor is 4 hours, and finally the direct reduced iron powder with the metallization rate of 97.8 percent can be obtained.
Experimental example 3
The particle iron oxide with the particle size distribution of 40-100 meshes (150-380 mu m and the average particle size of 0.28mm) has the chemical composition of total iron, FeO and SiO2、Al2O3MnO contents of 62.67%, 0.59%, 4.52%, 1.59% and 0.26% respectively, preheating granular iron oxide to 650 deg.C, continuously adding into an air-suspension rotary kiln reactor, and making reducing gas into H275% of CO, 8% of CO2Content of 0.5%, N2The content is 16.5 percent, reducing gas is preheated to 600 ℃ and is introduced into an air-suspension type rotary kiln reactor, the operating pressure of the air-suspension type rotary kiln reactor is 1.0MPa, the retention time of the granular iron oxide in the air-suspension type rotary kiln reactor is 4.5 hours, and finally the direct reduced iron powder with the metallization rate of 96.3 percent can be obtained, and the carbon content is 2.6 percent.
Experimental example 4
The iron oxide particles with the particle size distribution of 50-200 meshes (75-270 mu m and the average particle size of 0.15mm) have the chemical compositions of full iron, FeO and SiO2、Al2O3MnO contents of 66.2%, 1.4%, 5.2%, 0.43% and 0.06% respectively, preheating granular iron oxide to 650 deg.C, continuously adding into an air-suspension rotary kiln reactor, and making reducing gas into H2Content 90%, N2The content is 10 percent, reducing gas is preheated to 550 ℃ and is introducedThe operation pressure of the suspended rotary kiln reactor is 1.5MPa, the retention time of the granular iron oxide in the suspended rotary kiln reactor is 3h, and finally the direct reduced iron powder with the metallization rate of 98.1 percent can be obtained.
Experimental example 5
Particle iron oxide with particle size distribution of 100-300 meshes (48-150 μm, average particle size of 0.105 mm), total iron, FeO, SiO2、CaO、MgO、Al2O3The content of MnO is respectively 62.7%, 27.3%, 1.32%, 1.53%, 3.45%, 0.82% and 0.28%, the granular iron oxide is preheated to 600 deg.C, then continuously added into the air-suspension rotary kiln reactor, and the reducing gas composition is H2The content is more than 99.5 percent, reducing gas is preheated to 600 ℃ and is introduced into an air-suspension type rotary kiln reactor, the operating pressure of the air-suspension type rotary kiln reactor is 2.5MPa, the retention time of the granular iron oxide in the air-suspension type rotary kiln reactor is 8 hours, and finally the direct reduced iron powder with the metallization rate of 98.5 percent can be obtained.
Comparative example 1
The particle iron oxide with the particle size distribution of 5-40 meshes (380-4000 mu m and the average particle size of 1.05mm) has the chemical composition of total iron, FeO and SiO2、CaO、MgO、Al2O3MnO contents of 55.2%, 0.29%, 8.69%, 0.01%, 6.53% and 0.07% respectively, preheating granular iron oxide to 750 deg.C, continuously adding into rotary kiln similar to the invented suspended rotary kiln reactor, and making reducing gas composition be H288% of CO, 0.5% of CO2Content 0.3%, CH4Content 2.5%, N2The content is 8.7%, reducing gas is preheated to 500 ℃ and is introduced into the rotary kiln, the difference is that a lifting component is not arranged in a cylinder body in the rotary kiln of the comparative example, the operating pressure of the rotary kiln is 0.6MPa, the retention time of the granular iron oxide in the rotary kiln is 15 hours, and finally the direct reduced iron powder with the metallization rate of 28.5% and the carbon content of 0.05% can be obtained.
Comparative example 2
Particle iron oxide with particle size distribution of 100-300 meshes (48-150 μm, average particle size of 0.105 mm), total iron, FeO, SiO2、CaO、MgO、Al2O3MnO contents of 62.7%, 27.3%, 1.32%, 1.53%, 3.45%, 0.82%, 0.28% respectively, granular iron oxide preheated to 600 ℃ was continuously added to a rotary kiln similar to the open-suspension rotary kiln reactor of the present invention, except that no reducing holes were provided at the head and tail of the kiln, no guide plates were provided at the feed and discharge positions, and the composition of the reducing gas was H2The content is more than 99.5 percent, reducing gas is preheated to 600 ℃ and is introduced into the rotary kiln, the operating pressure of the rotary kiln is 0.2MPa, the thickness of a material layer is about 1/3 of example 5, the residence time of the granular iron oxide in the rotary kiln is 8 hours, and finally the direct reduced iron powder with the metallization rate of 53.4 percent can be obtained.
Through designing a plurality of structures of the rotary kiln reactor, the air-suspension type rotary kiln reactor can operate under high pressure, the solid loading capacity is large, the gas-solid contact efficiency is higher, and by adopting the rotary kiln reactor, the direct reduced iron powder with the metallization rate of more than 95 percent can be obtained.
Through comparison between comparative example 1 and experimental example 1, it can be seen that the lifting component on the rotary kiln cylinder is very critical, so that solid materials can form curtain-type distribution, and a good contact effect of gas phase and solid phase is achieved. Compared with a rotary kiln without a shoveling plate and a lifting plate, the rotary kiln can only obtain a product with a low metallization rate even if a longer reaction time is adopted, and the product with the metallization rate less than 50 percent can hardly be sold as a product and can only be used as a raw material of a blast furnace or other iron-making processes.
Through comparison between comparative example 2 and experimental example 5, it can be seen that the guide plates arranged at the reducing design and the feeding and discharging positions of the rotary kiln are very important, the reducing and guide plate design improves the solid loading capacity while keeping the feeding and discharging very smooth, the cylindrical body of the straight cylindrical rotary kiln is difficult to form a high material layer thickness due to easy discharge of the material at the discharge port, even if a special lifting assembly is arranged under the operation condition of a low material layer thickness, enough material does not form a rain curtain type material channel, the gas is easy to short circuit, meanwhile, a large sealing system also causes that the particularly high pressure cannot be maintained in the furnace, otherwise, the reducing gas is easy to leak, the reducing gas quantity can only be reduced under the same gas operation gas speed, the solid material layer thickness is lower, the solid retention time is ensured to be unchanged, and the solid feeding speed is also reduced, this results in that the metallization ratio of the product is rather lowered although the productivity is lowered. Through the design of the reducing and guide plates and the function of the lifting and shoveling assembly, a product with high metallization rate can be obtained at the same time of large flux.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (8)
1. An air-suspension rotary kiln reactor, comprising: the rotary kiln comprises a rotary kiln barrel, wherein the rotary kiln barrel comprises a main barrel and a variable-diameter part connected to two ends of the main barrel and gradually contracted outwards respectively, the contracted ends of the variable-diameter part are connected with rotary shell sections, the rotary shell sections are connected with a sealing mechanism, and a sealing assembly is arranged at the joint of the sealing mechanism and the rotary shell sections;
a plurality of lifting components are arranged inside the main cylinder body, each lifting component comprises a lifting plate and a lifting plate, one end of each lifting plate is connected to the inner wall of the main cylinder body, and the other end of each lifting plate is connected with the lifting plate;
the lifting components comprise a plurality of sections which are uniformly distributed at intervals along the axial direction of the main cylinder body, and each section of the lifting components is uniformly distributed at intervals along the radial direction of the main cylinder body, so that a plurality of material curtains are formed when the particle iron oxide rotates in the rotary kiln cylinder body, and the reducing gas passes through the plurality of material curtains and is fully contacted with the particle iron oxide.
2. An air-suspension rotary kiln reactor according to claim 1, wherein the closure mechanism is disposed radially outwardly of the rotary shell ring, at least a portion of the rotary shell ring extending into the interior of the closure mechanism; the sealing mechanism comprises a sealing shell ring, an expansion joint and a sealing head, and the sealing assembly is arranged at the joint of the sealing shell ring and the rotary shell ring.
3. An air-suspension rotary kiln reactor according to claim 1, wherein the rotary shell section comprises a kiln head rotary shell section and a kiln tail rotary shell section, the sealing mechanism comprises a kiln head sealing mechanism and a kiln tail sealing mechanism, and a cooling gas inlet is formed in the kiln head sealing mechanism.
4. The air-suspension rotary kiln reactor according to claim 3, wherein the kiln head closing mechanism comprises a kiln head closing cylinder section, a kiln head expansion joint and a kiln head end socket, the kiln tail closing mechanism comprises a kiln tail closing cylinder section, a kiln tail expansion joint and a kiln tail end socket, an air inlet pipe for air inlet is connected to the kiln head end socket, and an air outlet pipe for air exhaust is connected to the kiln tail end socket;
at least one part of the air inlet pipe extends into the rotary shell ring of the kiln head, and at least one part of the air outlet pipe extends into the rotary kiln barrel.
5. The suspended rotary kiln reactor according to claim 4, wherein a feeding screw for feeding is arranged in the kiln tail closing mechanism, and a locking feeding hopper for sealing feeding is arranged at the upper part of the feeding screw; the kiln head sealing mechanism is characterized in that a discharging spiral used for discharging is arranged inside the kiln head sealing mechanism, a discharging port is formed in the bottom of the kiln head sealing head, and the discharging port is connected with a locking discharging hopper used for closed discharging.
6. The air-suspension rotary kiln reactor according to claim 3, wherein the diameter-variable part comprises a kiln head reducing part, and a kiln head reducing guide plate and a kiln head guide plate for guiding out materials are respectively arranged inside the kiln head reducing part and the kiln head rotary cylinder section.
7. The air-suspension rotary kiln reactor according to claim 6, wherein the kiln head reducing guide plate is arranged in an inclined manner towards the rotation direction of the rotary kiln cylinder;
the kiln head guide plate is arranged at the joint of the kiln head rotary cylinder section and the kiln head reducing diameter.
8. The air-suspension rotary kiln reactor according to claim 1, wherein the shovelling plates extend in the radial direction of the main cylinder, and the ratio of the length of the shovelling plates to the diameter of the main cylinder is 1:20-1: 3; the lifting plate is of a semicircular bent plate structure, and the ratio of the radius of the lifting plate to the length of the shoveling plate is 1:10-1: 2; the width of the shovelling plate is the same as that of the lifting plate.
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