CN114737051B

CN114737051B - Iron-containing pellet direct reduction process and system based on hot air external circulation of rotary kiln-melting furnace

Info

Publication number: CN114737051B
Application number: CN202210446955.4A
Authority: CN
Inventors: 胡兵; 刘臣; 郑富强; 师本敬; 王兆才; 张震; 何璐瑶
Original assignee: Zhongye Changtian International Engineering Co Ltd
Current assignee: Zhongye Changtian International Engineering Co Ltd
Priority date: 2022-01-04
Filing date: 2022-04-26
Publication date: 2023-10-03
Anticipated expiration: 2042-04-26
Also published as: WO2023130752A1; CN114737051A

Abstract

The invention discloses a direct reduction process and a direct reduction system of iron-containing pellets based on hot air external circulation of a rotary kiln-melting furnace, which are used for realizing low-temperature rapid reduction of a coal-based rotary kiln, wherein the coal-based rotary kiln is divided into a drying section, a preheating section, a plasma reduction section, a reduction roasting section and a slow cooling section in sequence by adopting a method of rotary kiln pre-reduction-melting furnace deep reduction; reforming the gas overflowed from the top of the melting furnace, and converting part of sensible heat into CO and H ₂ Chemical energy potential, and then CO and H are added again ₂ Activated to plasma state CO ⁺ Or H ⁺ And then the reducing atmosphere of the material layer in the rotary kiln is enhanced, the diffusion of the reducing agent in the iron ore pellet particles is enhanced, the reduction reaction of the low-temperature Duan Haiyuan agent at the interfaces of the iron ore pellet particles is enhanced, and the purposes of saving energy, reducing emission and improving production efficiency are achieved.

Description

Iron-containing pellet direct reduction process and system based on hot air external circulation of rotary kiln-melting furnace

Technical Field

The invention relates to a direct reduction technology of iron-containing pellets, in particular to a direct reduction technology of iron-containing pellets based on hot air external circulation of a rotary kiln-melting furnace and a direct reduction system of iron-containing pellets, and belongs to the technical field of iron-making production.

Background

The process for extracting metallic iron from iron-bearing minerals (mainly iron oxides) mainly includes blast furnace method, direct reduction method, smelting reduction method, etc. From a metallurgical point of view, iron-making is the reverse of the rusting and progressive mineralization of iron, simply by the reduction of pure iron from iron-containing compounds. A production process for reducing iron ore with a reducing agent at high temperature to obtain pig iron. Iron-making is mainly made of iron ore and coke; the purpose of the coke is to provide heat and produce the reductant carbon monoxide.

Blast furnace smelting is a continuous production process for reducing iron ore to pig iron. The solid raw materials such as iron ore, coke, flux and the like are fed into a blast furnace in batches by a top charging device according to a specified proportioning ratio, and the throat level is kept at a certain height. The coke and ore form alternating layered structures within the furnace. The blast furnace method is adopted for iron making, and has the technical problems of long production period, low production efficiency, large energy consumption, large pollutant production amount and the like.

Direct Reduced Iron (DRI) is an ideal raw material for scrap steel supplements and for smelting high quality specialty steels in short-process steelmaking processes. In recent years, the worldwide production of direct reduced iron has rapidly progressed. Because of the lack of iron ore resources and natural gas, the development of the direct reduction process in China is slow, research and practice hot spots are also focused on the coal-based direct reduction process, and non-coking coal is adopted to produce direct reduced iron or metallic iron. In the existing coal-based direct reduction process, oxidized pellets or cold bonded pellets are generally used as raw materials to react in a rotary kiln to produce DRI. In the direct reduction process of the coal-based rotary kiln, the time from charging to discharging of the furnace burden is 6-8 hours, the production period is longer, and the production efficiency is low. The productivity of the rotary kiln direct reduction process, i.e. how much product is produced by the rotary kiln per unit time, is generally related to the size and structure of the kiln, the raw material and fuel conditions, the temperature and temperature distribution in the kiln, the atmosphere and the charge amount, etc., and the reduction rate of pellets is a fundamental factor affecting the direct reduction production cycle and production efficiency.

At present, the time required from furnace charge entering to product exiting in the direct reduction process of the coal-based rotary kiln can be as long as 8 hours, the production period is longer, and the production efficiency is low. The low pellet reduction speed and long heat preservation reduction time in the rotary kiln are root causes of low production efficiency and long production period of the coal-based rotary kiln direct reduction process. In order to improve the reduction speed of direct reduction, researchers and practitioners put forward some technical measures in the aspects of kiln body design (CN 110229939A, a two-section rotary kiln non-coke iron-making device), pellet batching (CN 106591572A, a method for preparing and reducing reinforced iron ore internally-matched carbon pellets) and the like, but the practicability of industrial application is poor, and most of the methods still stay in an experimental stage at present and have not been popularized and applied yet.

The reducing agent in the direct reduction process of the coal-based rotary kiln is anthracite, and the reduction process mainly involves brief reduction reaction of iron oxide and gasification reaction of coal, namely:

Fe _x O _y +C＝Fe _x O _y-1 +CO (1)

Fe _x O _y +CO＝Fe _x O _y-1 +CO ₂ (2)

C+CO ₂ ＝2CO (3)

the reaction activation energy of the formula (1) is 140-400kJ/mol, the reaction activation energy of the formula (2) is 60-80kJ/mol, and the reaction activation energy of the formula (3) is 170-200kJ/mol. In fact, equation (1) proceeds very slowly relative to equations (2) and (3), and is negligible. Currently researchers mostly believe that the formation of C between solid carbon and iron oxide is generally through the Boolean reaction (formula (3)) O reacts with the iron oxide, i.e. the solid carbon is mainly CO ₂ Reduction to CO generally occurs rarely directly with iron oxide. The reduction reaction is carried out from the outside of the pellets to the pellets, and the gasification speed of carbon and the diffusion speed of gas in the pellets have great influence on the reduction reaction. In the reduction process, the reduction reaction of the pellets is controlled by interfacial chemical reaction and internal diffusion mixing. As the reduction reaction proceeds, the chemical reaction resistance is decreasing and the internal diffusion resistance is increasing. Therefore, the reducing gas in the middle and later stages of reduction is difficult to enter the pellet cores, the reduction degree is gradually increased, and the method is an important reason for influencing the overall reduction speed.

In order to improve the reduction speed of direct reduction, researchers and practitioners put forward some technical measures in the aspects of kiln body design (such as CN110229939A, a two-section rotary kiln non-coke iron-making device), pellet batching (such as CN106591572A, a method for preparing and reducing reinforced carbon pellets in iron ores) and the like, but the practicability of industrial application is poor, most of the current methods still stay in an experimental stage, and the methods are not popularized and applied yet.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a direct reduction process of iron-containing pellets based on the external circulation of hot air of a rotary kiln-melting furnace and a direct reduction system of iron-containing pellets. Aiming at the problems of slow diffusion speed of reducing gas in the middle and later stages of reduction and slow pellet reduction speed in the existing coal-based rotary kiln direct reduction process, which result in slow pellet reduction speed in the whole process and long heat preservation reduction time of pellets in a kiln body, the invention adopts a method of deep reduction of a rotary kiln pre-reduction-melting furnace, the coal-based rotary kiln is divided into a drying section, a preheating section, a plasma reduction section, a reduction roasting section and a slow cooling section in sequence, and a coal gas reforming vertical shaft and an ash separation device are arranged between the rotary kiln and the melting furnace. Reforming high-temperature gas overflowed from the top of the melting separation furnace through a vertical shaft, circulating the tail gas of the rotary kiln to the vertical shaft or an ash separation section, and converting part of sensible heat of the tail gas into CO and H ₂ Chemical energy potential, and then CO and H are added again ₂ Activated to plasma state CO ⁺ Or H ⁺ Rear-opening deviceThe lower part of the passing material layer is introduced, so that the reducing atmosphere of the material layer is enhanced, the diffusion of the reducing agent in the iron-containing pellet particles is enhanced, and the reduction reaction of the low-temperature Duan Haiyuan agent at the pellet particle interface is enhanced.

In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:

according to a first embodiment of the invention, a direct reduction process of iron-containing pellets based on the external circulation of hot air of a rotary kiln-melting furnace is provided.

An iron-containing pellet direct reduction process based on the external circulation of hot air of a rotary kiln-a melting furnace, which comprises the following steps:

1) According to the trend of the materials, the iron-containing pellets are sent into a rotary kiln from the kiln tail and subjected to pre-reduction treatment sequentially through a drying section, a preheating section, a plasma reduction section, a reduction roasting section and a slow cooling section, so that a pre-reduction product is obtained. And then the pre-reduction product is conveyed into a melting furnace for deep reduction treatment after passing through a vertical shaft or sequentially passing through the vertical shaft and an ash separation device, so as to obtain molten iron.

2) And (3) carrying out gas reforming on high-temperature gas generated in the melting furnace to obtain reformed gas, and then conveying the reformed gas into a rotary kiln to participate in the pre-reduction treatment of the iron-containing pellets. Meanwhile, the tail gas of the rotary kiln is circulated to participate in the reforming treatment of the high-temperature gas.

Preferably, the step 2) specifically comprises:

201 Conveying high-temperature gas at the top of the melting separation furnace into a vertical shaft for reforming to obtain reformed gas, and then conveying the reformed gas to a plasma reduction section for participating in pre-reduction treatment of the iron-containing pellets after plasma activation. And simultaneously pumping the tail gas of the rotary kiln into the vertical shaft, and adjusting the pumping quantity of the tail gas of the rotary kiln according to the real-time temperature change of the materials in the vertical shaft.

Alternatively, the step 2) specifically includes:

202 Conveying high-temperature gas at the top of the melting separation furnace into a vertical shaft for reforming to obtain reformed gas, and then conveying the reformed gas to a plasma reduction section for participating in pre-reduction treatment of the iron-containing pellets after plasma activation. And simultaneously pumping the rotary kiln tail gas into an ash separation device, and adjusting the pumping quantity of the rotary kiln tail gas according to the real-time temperature change of smoke dust in the ash separation device. And finally, carrying out plasma activation on tail gas discharged from the ash separation device, and then conveying the tail gas to a plasma reduction section to participate in the pre-reduction treatment of the iron-containing pellets.

Preferably, in step 201), the extraction amount of the tail gas of the rotary kiln is adjusted according to the real-time temperature change of the materials in the shaft, specifically: the temperature of the materials in the vertical shaft is set to be T1 + -C1 (the range of C1 is 0-50) DEG C. And detecting the real-time temperature of the materials in the vertical shaft to be T2 at the temperature of DEG C in real time. Then:

When T2 > (T1 + -C1), increasing the extraction amount of the tail gas of the rotary kiln until the real-time temperature of the materials in the vertical shaft returns to the preset temperature (T1 + -C1).

When T2 epsilon (T1 + -C1), the current process conditions are maintained unchanged.

When T2 < (T1 + -C1), the extraction amount of the tail gas of the rotary kiln is reduced until the real-time temperature of the materials in the vertical shaft returns to the preset temperature (T1 + -C1).

Preferably, in step 202), the extraction amount of the rotary kiln exhaust gas is adjusted according to the real-time temperature change of the smoke dust in the ash separation device, specifically: the temperature of the smoke dust in the ash separation device is set to be T3+/-C2 (the range of C2 is 0-50) and the temperature is set to be lower than the temperature. And detecting the real-time temperature of smoke dust in the ash separation device to be T4 and DEG C in real time. Then:

when T4 > (T3+/-C2), the extraction amount of the tail gas of the rotary kiln is increased until the real-time temperature of the smoke dust in the ash separation device returns to the preset temperature (T3+/-C2).

When T4 epsilon (T3+/-C2), the current process condition is maintained unchanged.

And when T4 < (T3+/-C2), reducing the extraction amount of the tail gas of the rotary kiln until the real-time temperature of the smoke dust in the ash separation device returns to the preset temperature (T3+/-C2).

Preferably, the temperature of the high temperature gas exiting the top of the melting furnace is greater than 1400 ℃, preferably greater than 1500 ℃, more preferably greater than 1600 ℃.

Preferably, the content of CO in the reformed gas is higher than 30vol%, preferably higher than 35vol%, more preferably higher than 40vol%. H ₂ Is higher than 2vol%,preferably H ₂ The content of (C) is higher than 3vol%, more preferably H ₂ The content of (2) is higher than 5vol%.

According to a second embodiment of the present invention, a direct reduction system for iron-containing pellets is provided.

A direct reduction system for iron-bearing pellets or a system for use in the process of the first embodiment, the system comprising a rotary kiln, a melting furnace and a microwave plasma initiator. According to the trend of the materials, the rotary kiln is sequentially provided with a drying section, a preheating section, a plasma reduction section, a reduction roasting section and a slow cooling section. The discharge hole of the slow cooling section is directly communicated with the feed inlet of the melting furnace through a vertical shaft. Or the discharge port of the slow cooling section is communicated with the feed inlet of the ash separation device through a vertical shaft, and the discharge port of the ash separation device is communicated with the feed inlet of the melting furnace. The microwave plasma exciter is arranged outside the plasma reduction section, and an exhaust port of the microwave plasma exciter is communicated with the bottom air inlet of the plasma reduction section. An air flow external circulation system is arranged between the melting furnace and the rotary kiln. Preferably, the ash separation device comprises a shell and a vibrating screen ash conveying mechanism. The vibrating screen ash conveying mechanism is arranged in the shell barrel and is communicated with the feed inlet and the discharge outlet of the shell barrel.

Preferably, the wind flow external circulation system includes: the top exhaust port of the melting furnace is communicated with the bottom air inlet of the vertical shaft through a first pipeline, and then the top exhaust port of the vertical shaft is communicated with the air inlet of the microwave plasma exciter through a second pipeline.

Preferably, the kiln tail of the rotary kiln is communicated with the bottom air inlet of the vertical shaft or the bottom air inlet of the ash separation device through a third pipeline, and then the top air outlet of the ash separation device is communicated with the air inlet of the microwave plasma exciter through a fourth pipeline.

Preferably, the system further comprises a temperature detection device. The temperature detection device is independently arranged in the vertical shaft and the ash separation device.

Preferably, the device further comprises a burner and a fuel delivery pipe. The burner is arranged in the reduction roasting section and is communicated with the fuel conveying pipeline. And the fuel conveying pipeline is also communicated with a combustion-supporting air pipe outside the rotary kiln.

Preferably, a plurality of burners are arranged in the reduction roasting section, and the burners are communicated with the fuel conveying pipeline.

Preferably, the rotary kiln further comprises a kiln body air duct mechanism, an annular rotary sliding rail and a rotary sliding mechanism. The annular rotary slide rail is sleeved outside the rotary kiln and is supported by the support. The wheel end of the rotary sliding mechanism is connected with the annular rotary sliding rail, the other end of the rotary sliding mechanism is connected with the outer end of the kiln body air duct mechanism, and the inner end of the kiln body air duct mechanism is connected with the kiln wall. Namely, the rotary kiln and the kiln body air duct mechanism can simultaneously rotate on the annular rotary slide rail through the rotary sliding mechanism.

Preferably, a plurality of annular rotary slide rails are arranged outside the rotary kiln. Any one annular rotary slide rail is connected with the rotary kiln through a plurality of rotary sliding mechanisms and a plurality of kiln body air duct mechanisms.

Preferably, the kiln body air duct mechanism comprises an air inlet connecting piece, a stop valve, a pull rod and an air inlet. An air inlet channel is formed in the kiln body of the rotary kiln. One end of the stop valve extends into the air inlet channel, and the other end of the stop valve is communicated with the air inlet connecting piece. The air inlet is arranged on the air inlet connecting piece. One end of the air inlet connecting piece, which is far away from the rotary kiln, is connected with one end of the pull rod, and the other end of the pull rod is connected with the rotary sliding mechanism.

Preferably, the rotary sliding mechanism comprises a rotary wheel seat, a lateral rotary wheel and a vertical rotary wheel. The rotary wheel seat is of a concave groove structure and is meshed with two side edge parts of the annular rotary slide rail. And lateral rotating wheels are arranged on the rotating wheel seats positioned on the side surfaces of the annular rotating slide rail. And vertical rotating wheels are arranged on the rotating wheel seats positioned on the outer bottom surface of the annular rotating slide rail. The rotary wheel seat can rotationally slide on the annular rotary slide rail through the lateral rotary wheel and the vertical rotary wheel.

Preferably, the rotary kiln further comprises a horizontal sliding mechanism. The horizontal sliding mechanism comprises a horizontal wheel seat, a horizontal pulley and a horizontal rail. The horizontal track is a groove-shaped track arranged at the upper end of the bracket. The bottom of the horizontal wheel seat is arranged in the horizontal track through a horizontal pulley. The top end of the horizontal wheel seat is connected with the annular rotary slide rail.

Preferably, the device further comprises a slewing mechanism. The slewing mechanism comprises a slewing motor and a large gear ring. The inner ring of the large gear ring is fixed on the outer wall of the rotary kiln, and the outer ring of the large gear ring is meshed and connected with a transmission gear of the rotary motor.

Aiming at the technical problems of high energy consumption, longer production period, low production efficiency and the like of adopting a rotary kiln to reduce iron oxide in a process for treating the iron oxide by adopting a direct reduction method, the invention provides a technical scheme of adopting a rotary kiln pre-reduction and a melting furnace deep reduction; preliminary reduction (pre-reduction) of iron oxide is carried out by a rotary kiln, and Fe easily occurs in the process of reducing the iron oxide into metallic iron ₂ O ₃ →Fe ₃ O ₄ →Fe _x The reduction reaction of the O stage is completed in a rotary kiln, the reaction period of the process is longer, and the processes of drying, preheating and the like are needed to be carried out on the iron oxide; fe is added to _x The deep reduction reaction of the O-Fe stage is completed in a melting furnace, and the stage needs a high-temperature environment to realize the high reduction of iron. By adopting the technical scheme of the rotary kiln pre-reduction and the smelting furnace deep reduction, the direct reduction efficiency of the iron oxide is greatly improved, and the energy consumption in the direct reduction process is saved by reasonable process adjustment.

In a preferred embodiment of the present invention, the reaction of iron oxide with carbon occurs in the deep reduction process of the melting furnace, and iron, carbon monoxide and part of carbon dioxide are produced, specifically: fe (Fe) _x O(s)+C＝xFe(s)+CO(g)+CO ₂ (g) A. The invention relates to a method for producing a fibre-reinforced plastic composite This reaction step yields high temperature carbon monoxide and carbon dioxide gas, referred to as "high temperature gas" or "top gas". The temperature of the high-temperature gas generated in the melting furnace is more than 1400 ℃, the highest temperature can be more than 1700 ℃, and the high-temperature gas has certain pressure. In the technical scheme of the invention, the heat and the heat value of the high-temperature gas are fully utilized, the high-temperature environment is needed in the rotary kiln, meanwhile, the reducing gas is needed, and the high-temperature gas generated by the melting furnace passes throughMicrowave plasma reactor excitation to CO and H ₂ Activated to plasma state CO ⁺ Or H ⁺ And then the gas is conveyed into a rotary kiln to serve as a reducing agent, and meanwhile, the heat of the partial gas is fully utilized, so that the maximum utilization of resources is realized.

In a preferred embodiment of the present invention, the reaction of iron oxide with carbon occurs in the deep reduction process of the melting furnace, and iron, carbon monoxide and part of carbon dioxide are produced, specifically: fe (Fe) _x O(s)+C＝xFe(s)+CO(g)+CO ₂ (g) A. The invention relates to a method for producing a fibre-reinforced plastic composite This reaction step gives high-temperature carbon monoxide and carbon dioxide gas, which are collectively referred to as "high-temperature gas". The temperature of the high-temperature gas generated in the melting furnace is more than 1400 ℃, the highest temperature can be more than 1700 ℃, and the high-temperature gas has certain pressure. In the technical scheme of the invention, the heat and the heat value of the high-temperature gas are fully utilized, the high-temperature environment is needed in the rotary kiln, meanwhile, the reducing gas is needed, the high-temperature gas generated by the deep reduction device is conveyed into the rotary kiln and serves as a reducing agent, and meanwhile, the heat of the part of gas is fully utilized, so that the maximum utilization of resources is realized.

In the invention, a large amount of high-temperature gas with the temperature of more than 1500 ℃ produced at the top of the melting furnace contains a large amount of unreacted CO and H ₂ In addition, contains a large amount of CO ₂ And water vapor, the main components of which are CO (about 21 percent), CO ₂ (about 25%), H ₂ (about 4%), N ₂ (about 48%), H ₂ O (about 2%). The product of the pre-reduction in the coal-based rotary kiln mainly comprises high-temperature pre-reduction raw materials and high-temperature residual coal. The technology carries out countercurrent reaction on the high-temperature pre-reduction product of the coal-based rotary kiln and a deep reduction device, and CO and H in high-temperature coal gas ₂ CO and H when passing through the high temperature pre-reduction product layer ₂ Can be subjected to reduction reaction with unreacted iron oxide to promote the further reduction of the pre-returned raw material. CO generated by reduction reaction in deep reduction device ₂ And H ₂ O and CO in high-temperature gas ₂ And H ₂ When O passes through the hot residual coal of the high-temperature pre-reduction product, boolean reaction and water gas reaction occur, so that the reforming of the high-temperature gas is realized.

Further, the high-temperature gas generated by the melting furnace is excited by a microwave plasma reactor to lead CO and H ₂ Activated to plasma state CO ⁺ Or H ⁺ And then is conveyed into a rotary kiln. CO and H in reformed gas ₂ The content is increased, the mixture is introduced into a plasma reduction section of the rotary kiln from the lower part of the material layer, and CO and H are excited by a microwave plasma reactor ₂ Activated to plasma state CO ⁺ Or H ⁺ ：

CO _(g) ＝CO ⁺ _(g) +e ^-

H _2(g) ＝2H ⁺ _(g) +2e ^-

CO in plasma state ⁺ Or H ⁺ Very high activity, and far higher oxygen-capturing capacity than CO or H in gaseous form ₂ The method is extremely easy to generate reduction reaction with the iron oxide, and can abstract oxygen in the iron oxide to realize efficient implementation of the reduction reaction:

Fe ₂ O _3(s) +3CO ⁺ _(g) +3e ^- ＝2Fe _(s) +3CO _2(g)

Fe ₂ O _3(s) +6H ⁺ _(g) +6e ^- ＝2Fe _(s) +3H ₂ O _(g)

in the invention, the tail gas of the rotary kiln contains a large amount of water vapor and CO ₂ The rotary kiln tail gas is sent to an ash separation section after gas reforming after multi-tube dust removal, and is blown in from the lower part of a material layer, and CO in the tail gas ₂ And H ₂ When O passes through the hot residual coal, boolean reaction and water gas reaction occur, and the following reactions mainly occur:

CO _2(g) +C _(s) ＝2CO _(g)

H ₂ O _(g) +C _(s) ＝CO _(g)+ H _2(g)

CO and H in tail gas ₂ The content is increased, the mixture is introduced into a plasma reduction section of the rotary kiln from the lower part of the material layer, and CO and H are excited by a microwave plasma reactor ₂ Activated to plasma state CO ⁺ Or H ⁺ Then reacts with the iron-containing raw material to realize reduction reactionShould be performed efficiently. The technical scheme mainly has the effects that firstly, ash in the pre-reduction product is separated by utilizing the tail gas of the rotary kiln, an additional inert gas loop is not required to be established, and the gas quantity of the system is not increased; secondly, the content of useless solids entering the smelting reduction furnace is effectively reduced, and the energy consumption of the smelting reduction furnace is reduced; thirdly, the heat in the tail gas of the rotary kiln is utilized, so that the energy is saved; fourth, the tail gas is heated by utilizing the heat of the pre-reduction product material layer, so as to supplement heat for the material in the plasma section; fifth, partial CO in the tail gas of the rotary kiln ₂ And H ₂ Conversion of O to CO and H ₂ The reducing atmosphere in the plasma section material layer is improved; sixth, CO in the tail gas of the rotary kiln ₂ And H ₂ O and conversion to CO and H ₂ The plasma is activated into a plasma state by a plasma exciter, so that the reduction reaction is enhanced.

In the invention, as the high-temperature gas generated by the deep reduction device contains a part of carbon dioxide, the pre-reduction product discharged by the rotary kiln also contains a part of carbon residue, and the environment with high temperature is provided; in the preferred scheme of the invention, a gas reforming process is added, and carbon dioxide in the high-temperature gas can be subjected to Boolean reaction (C+CO) with residual carbon in the pre-reduction product ₂ =2co), generating carbon monoxide; the water in the high temperature gas reacts with the residual carbon in the pre-reduction product to produce water gas (H ₂ O(g)+C(s)＝CO(g)+H ₂ (g) Hydrogen and carbon monoxide. In the process of the gas reforming procedure, the high-temperature gas generated by the deep reduction device utilizes carbon in a pre-reduction product and a high-temperature environment to convert carbon dioxide and water in the high-temperature gas into reducing gases such as carbon monoxide, hydrogen and the like through reaction, so that the content of the reducing gases in the gases conveyed to the rotary kiln is further improved, the reformed high-temperature gas is activated into a plasma state and then conveyed to the rotary kiln, and the high-temperature plasma state reducing gases enter the pre-reduction procedure in the rotary kiln and are used for reducing iron oxides. By the technical means, the active ingredients and the product environment in the pre-reduction product and the deep reduction device product are fully utilized, the optimization of the technical scheme is realized, and the reducibility in high-temperature gas is further improved while the resources are fully utilized The content of the gas further improves the reduction efficiency in the rotary kiln; the high-temperature gas generated by the deep reduction device is utilized, so that the use amount of fuel in the rotary kiln is also saved; by adopting the technical scheme of the invention, the carbon distribution amount in the raw materials entering the rotary kiln can be reduced, and compared with the prior art, the fuel consumption can be saved by 20-30% by adopting the technical scheme of the invention.

According to the invention, the high-temperature gas is reformed through the reforming vertical shaft, so that the pre-reduction product is further reduced. The sensible heat of the pre-reduction product of the rotary kiln, the sensible heat of the high-temperature gas and the reducing gas in the sensible heat are fully utilized, so that the further pre-reduction of the iron oxide is realized. Part of iron oxide does not finish the reduction reaction process in the pre-reduction process of the coal-based rotary kiln, and CO and H in high-temperature coal gas are in the coal gas reforming high-temperature reaction material layer ₂ And (3) continuing to perform further pre-reduction reaction on unreduced iron oxide, improving the reduction degree of raw materials fed into the furnace by the deep reduction device, and reducing the energy consumption of the deep reduction device.

In addition, fully utilizes CO in high Wen Can coal and high-temperature coal gas in the rotary kiln pre-reduction product ₂ And H ₂ O and CO generated by reduction of iron oxide in material layer ₂ And H ₂ O, generating gas reforming reaction, converting sensible heat of the above materials and gas flow into high-quality reducing gases CO and H ₂ Converting sensible heat into chemical energy of reducing gas, and reforming to obtain a large amount of CO and H ₂ The heat can be provided for the direct reduction reaction of the rotary kiln through oxidation heat release, and the heat can also be used as a reducing agent for the direct reduction reaction of the rotary kiln, so that the energy loss caused by cooling of high-temperature gas in the transmission process can be reduced, and the reduction gas CO and H in the gas fed into the rotary kiln can also be enhanced ₂ The content of the iron oxide in the rotary kiln is enhanced.

In addition, the temperature of the pre-reduction product of the rotary kiln is about 1200 ℃, the temperature of high-temperature gas generated by the smelting reduction furnace is more than 1500 ℃ and can be up to 1700 ℃ at most, when the pre-reduction product and the high-temperature gas are subjected to the countercurrent reforming reaction, the pre-reduction product of 1200 ℃ moves from the upper part to the lower part, the high-temperature gas moves from the lower part of the material layer to the upper part, the reforming reaction can convert part of heat into chemical energy, the temperature of the gas can be gradually reduced, but in the process of gradually reducing the pre-reduction product, the temperature of the high-temperature gas is higher and higher as the temperature of the pre-reduction product is higher and higher, the temperature reduction of the pre-reduction product discharged from the rotary kiln head to the process of adding the smelting reduction furnace is reduced, and the energy consumption of the smelting reduction furnace is reduced.

In the invention, reformed high-temperature gas is transported to the rotary kiln after being plasmatized, and the heat is provided and simultaneously the gas mainly plays a role of a reducing agent. The content of reducing gas in the reformed high-temperature gas obtained after passing through the reforming shaft can be controlled by controlling the flow rate of the high-temperature gas discharged from the melting furnace in the reforming shaft, the temperature of the high-temperature gas entering the reforming shaft and other technological parameters. In order to ensure the reduction of the reformed high-temperature gas in the rotary kiln and also to ensure the pre-reduction degree of the iron oxide in the rotary kiln, in the invention, the content of CO in the reformed high-temperature gas is controlled to be higher than 35vol percent, H ₂ The content of (2) is higher than 5vol%.

In the invention, the gas reforming reaction is generally judged by on-line monitoring of the material temperature and the material surface gas composition of the gas reforming shaft, and further the gas reforming reaction and the temperature are controlled by the temperature field distribution in the gas reforming shaft and the circulating gas flow introduced into the material layer. Generally, a reference relation among the temperature of the top gas of the smelting reduction furnace, the tail gas flow of the rotary kiln, the temperature distribution of the vertical shaft and the gas reforming efficiency is established, and the range of the temperature distribution interval in the gas reforming vertical shaft is determined and used as a reference requirement for the subsequent regulation and control of the material reduction process in the rotary kiln and the smelting reduction furnace. And then the distribution of the material temperature field in the vertical shaft is monitored in real time through a temperature monitoring device and a material level gas component content monitoring device which are distributed in the gas reforming vertical shaft.

In a preferable rotary kiln-melting furnace hot air external circulation scheme, a part of rotary kiln tail gas is led into a gas reforming vertical shaft to be used as a main means for adjusting the temperature of the vertical shaft so as to ensure the efficient and rapid gas reforming. The extraction amount of the tail gas of the rotary kiln is regulated according to the real-time temperature change of the materials in the vertical shaft, and is specifically as follows: the temperature of the materials in the vertical shaft is set to be T1 + -C1 (the range of C1 is 0-50 ℃), and the temperature is set to be low. And detecting the real-time temperature of the materials in the vertical shaft to be T2 at the temperature of DEG C in real time. Then:

In the invention, a proper gas flow range required by ash separation is determined by establishing a reference relation among gas flow, ash separation effect in a reduction product of the rotary kiln and temperature of separated smoke dust, and the gas flow range is used as a reference requirement for subsequent regulation and control of ash separation. Through the temperature monitoring device of distribution ash separation smoke and dust, real-time supervision ash separation smoke and dust temperature distribution. Furthermore, the invention also uses the ash separation section after a part of the rotary kiln tail gas is led into the gas reforming vertical shaft as a main means for adjusting the temperature of the ash separation section, so that the invention can utilize more rotary kiln tail gas, reduce the energy consumption of the system, improve the production efficiency and achieve the purpose of low-temperature rapid reduction while ensuring good ash separation effect. The extraction amount of the tail gas of the rotary kiln is regulated according to the real-time temperature change of the smoke dust in the ash separation device, and is specifically as follows: the temperature of the smoke dust in the ash separation device is set to be T3+/-C2 (the range of C2 is 0-50) and the temperature is set to be lower than the temperature. And detecting the real-time temperature of smoke dust in the ash separation device to be T4 and DEG C in real time. Then:

In the present invention, the prereducing device may also be one of a rotary kiln, a rotary hearth furnace, a tunnel kiln, a fluidized bed or a shaft furnace. The deep reduction device (melting furnace) may be one of a melting reduction furnace, a converter, an electric furnace, or a blast furnace.

Compared with the prior art, the invention has the following beneficial technical effects:

1. the technology adopts a rotary kiln pre-reduction-melting furnace deep reduction method to reduce iron oxide into Fe which is easy to occur in the process of metallic iron ₂ O ₃ →Fe ₃ O ₄ →Fe _x The reduction reaction in the O stage is completed in a rotary kiln, and the pre-reduction product reaching a certain reduction degree and the residual coal are hot packed together and enter a melting furnace for deep reduction.

2. The invention utilizes the melting reduction process of the melting separation furnace to generate a large amount of high-temperature gas with the temperature of more than 1500 ℃, and utilizes the sensible heat and latent heat of the high-temperature gas and the reducing gas in the high-temperature gas to realize the prereduction of the iron oxide in the rotary kiln, thereby effectively reducing the energy consumption of the rotary kiln.

3. According to the invention, the high-temperature gas is reformed through the reforming vertical shaft, so that the pre-reduction product is further reduced. The sensible heat of the pre-reduction product of the rotary kiln, the sensible heat of the high-temperature gas and the reducing gas in the sensible heat are fully utilized, so that the further pre-reduction of the iron oxide is realized. In addition, in the reforming vertical shaft, CO in high Wen Can coal and high-temperature coal gas in the rotary kiln pre-reduction product is fully utilized ₂ And H ₂ O and CO generated by reduction of iron oxide in material layer ₂ And H ₂ O, generating gas reforming reaction to obtain CO and H ₂ . Further CO and H ₂ Excitation of CO and H by microwave plasma reactor ₂ Activated to plasma state CO ⁺ Or H ⁺ . And the reducing atmosphere of the material layer is enhanced, the diffusion of the reducing agent in the iron ore particles is enhanced, and the reduction reaction of the low-temperature Duan Haiyuan agent at the iron ore particle interface is enhanced by introducing the material layer at the lower part of the material layer.

4. The invention circularly uses the rotary kiln tail gas in an ash separation section, realizes the separation of ash in the pre-reduction product by using the rotary kiln tail gas, does not need to establish an additional inert gas loop, does not increase the gas quantity of the system,simultaneously, the content of useless solids entering the smelting reduction furnace is effectively reduced, and the energy consumption of the smelting reduction furnace is reduced; the tail gas is heated by utilizing the heat of the pre-reduction product layer to supplement heat for the material in the plasma section; further, part of CO in the tail gas of the rotary kiln ₂ And H ₂ Conversion of O to CO and H ₂ The reducing atmosphere in the plasma section material layer is improved; CO and H ₂ And then the reaction product is activated into a plasma state by a plasma exciter, so that the reduction reaction is enhanced.

Drawings

FIG. 1 is a flow chart of a direct reduction process of iron-containing pellets based on the external circulation of hot air of a rotary kiln-melting furnace.

FIG. 2 is a flow chart of a second process for directly reducing iron-containing pellets based on the external circulation of hot air of a rotary kiln-melting furnace.

FIG. 3 is a control flow chart of the direct reduction process of iron-containing pellets based on the external circulation of hot air of a rotary kiln-melting furnace.

FIG. 4 is a control flow chart of a second process for directly reducing iron-containing pellets based on the external circulation of hot air of a rotary kiln-melting furnace.

Fig. 5 is a schematic structural diagram of the iron-containing pellet direct reduction system of the present invention with an external circulation of wind.

Fig. 6 is a schematic structural diagram of the iron-containing pellet direct reduction system according to the present invention when the air flow external circulation is two.

Fig. 7 is a schematic structural diagram of a rotary kiln of the iron-bearing pellet direct reduction system of the present invention.

FIG. 8 is a cross-sectional view of A-A of the rotary kiln of the iron-bearing pellet direct reduction system of the present invention.

FIG. 9 is a perspective view of a rotary kiln A-A of the iron-bearing pellet direct reduction system of the present invention.

Reference numerals: 1: a rotary kiln; 101: a drying section; 102: a preheating section; 103: a plasma reduction section; 104: a reduction roasting section; 105: a slow cooling section; 106: a burner; 107: a fuel delivery conduit; 108: a combustion-supporting air pipe; 2: a melting furnace; 3: a microwave plasma exciter; 4: a shaft; 5: an ash separation device; 501: a shell barrel; 502: a vibrating screen ash conveying mechanism; 6: a temperature detecting device; 7: a kiln body air duct mechanism; 701: an air inlet connecting piece; 702: a stop valve; 703: a pull rod; 704: an air inlet; 705: an air inlet channel; 8: an annular rotary slide rail; 801: a bracket; 9: a rotary sliding mechanism; 901: a rotary wheel seat; 902: a lateral rotation wheel; 903: a vertical rotating wheel; 10: a horizontal sliding mechanism; 1001: a horizontal wheel seat; 1002: a horizontal pulley; 1003: a horizontal rail; 11: a slewing mechanism; 1101: a rotary motor; 1102: a large gear ring; 12: conductivity detection means; 1201: a detection coil; 1202: a magnetic core; l1: a first pipe; l2: a second pipe; l3: a third conduit; l4: and a fourth pipeline.

Detailed Description

The following examples illustrate the technical aspects of the invention, and the scope of the invention claimed includes but is not limited to the following examples.

A direct reduction system for iron-containing pellets comprises a rotary kiln 1, a melting furnace 2 and a microwave plasma exciter 3. According to the trend of the materials, the rotary kiln 1 is sequentially provided with a drying section 101, a preheating section 102, a plasma reduction section 103, a reduction roasting section 104 and a slow cooling section 105. The discharge port of the slow cooling section 105 is directly communicated with the feed port of the melting furnace 2 through the vertical shaft 4. Or the discharge port of the slow cooling section 105 is communicated with the feed port of the ash separation device 5 through the vertical shaft 4, and the discharge port of the ash separation device 5 is communicated with the feed port of the melting furnace 2. The microwave plasma exciter 3 is arranged outside the plasma reduction section 103, and an exhaust port of the microwave plasma exciter 3 is communicated with a bottom air inlet of the plasma reduction section 103. An air flow external circulation system is arranged between the melting furnace 2 and the rotary kiln 1. Preferably, the ash separation device 5 comprises a housing 501 and a vibrating screen ash feed mechanism 502. The vibrating screen ash conveying mechanism 502 is arranged in the shell 2501 and is communicated with a feed inlet and a discharge outlet of the shell 501.

Preferably, the wind flow external circulation system includes: the top exhaust port of the melting furnace 2 is communicated with the bottom air inlet of the vertical shaft 4 through a first pipeline L1, and the top exhaust port of the vertical shaft 4 is communicated with the air inlet of the microwave plasma exciter 3 through a second pipeline L2.

Preferably, the kiln tail of the rotary kiln 1 is communicated with the bottom air inlet of the vertical shaft 4 or the bottom air inlet of the ash separation device 5 through a third pipeline L3, and then the top air outlet of the ash separation device 5 is communicated with the air inlet of the microwave plasma exciter 3 through a fourth pipeline L4.

Preferably, the system further comprises temperature detection means 6. The temperature detection device 6 is independently arranged in the vertical shaft 4 and the ash separation device 5.

Preferably, the device further comprises a burner 106 and a fuel delivery pipe 107. The burner 106 is disposed within the reduction roasting section 104 and is in communication with a fuel delivery conduit 107. The fuel delivery pipe 107 is also communicated with a combustion-supporting air pipe 108 outside the rotary kiln 1.

Preferably, a plurality of burners 106 are arranged in the reduction roasting section 104, and each of the burners 106 is communicated with a fuel delivery pipe 107.

Preferably, the rotary kiln 1 further comprises a kiln body air duct mechanism 7, an annular rotary sliding rail 8 and a rotary sliding mechanism 9. The annular rotary slide rail 8 is sleeved outside the rotary kiln 1 and is supported by a bracket 801. The wheel end of the rotary sliding mechanism 9 is connected with the annular rotary sliding rail 8, the other end of the rotary sliding mechanism is connected with the outer end of the kiln body air duct mechanism 7, and the inner end of the kiln body air duct mechanism 7 is connected with the kiln wall. Namely, the rotary kiln 1 and the kiln body air duct mechanism 7 can simultaneously rotate on the annular rotary slide rail 8 through the rotary sliding mechanism 9.

Preferably, a plurality of annular rotary slide rails 8 are arranged outside the rotary kiln 1. Any one annular rotary slide rail 8 is connected with the rotary kiln 1 through a plurality of rotary slide mechanisms 9 and a plurality of kiln body air duct mechanisms 7.

Preferably, the kiln body air duct mechanism 7 comprises an air inlet connector 701, a baffle valve 702, a pull rod 703 and an air inlet 704. An air inlet channel 705 is formed in the kiln body of the rotary kiln 1. One end of the baffle 702 extends into the air inlet channel 705, and the other end of the baffle is communicated with the air inlet connecting piece 701. The air inlet 704 is formed on the air inlet connector 701. One end of the air inlet connecting piece 701, which is far away from the rotary kiln 1, is connected with one end of a pull rod 703, and the other end of the pull rod 703 is connected with a rotary sliding mechanism 9.

Preferably, the rotary slide mechanism 9 includes a rotary wheel base 901, a lateral rotary wheel 902, and a vertical rotary wheel 903. The rotary wheel seat 901 is of a concave groove structure and is meshed with two side edge parts of the annular rotary slide rail 8. Lateral rotating wheels 902 are provided on rotating wheel seats 901 located on the sides of the endless rotating slide rail 8. Vertical rotating wheels 903 are arranged on rotating wheel seats 901 positioned on the outer bottom surface of the annular rotating slide rail 8. The rotating wheel mount 901 is rotatably slidable on an annular rotary slide rail 8 by a side rotating wheel 902 and a vertical rotating wheel 903.

Preferably, the rotary kiln 1 further comprises a horizontal sliding mechanism 10. The horizontal sliding mechanism 10 includes a horizontal wheel seat 1001, a horizontal pulley 1002, and a horizontal rail 1003. The horizontal rail 1003 is a groove-shaped rail arranged at the upper end of the bracket 801. The bottom end of the horizontal wheel seat 1001 is mounted in the horizontal track 1003 by a horizontal pulley 1002. The top end of the horizontal wheel seat 1001 is connected to an annular rotary slide rail 8.

Preferably, the device further comprises a slewing mechanism 11. The swing mechanism 11 includes a swing motor 1101 and a ring gear 1102. The inner ring of the large gear ring 1102 is fixed on the outer wall of the rotary kiln 1, and the outer ring of the large gear ring 1102 is meshed and connected with a transmission gear of the rotary motor 1101.

Example 1

1) According to the trend of the materials, the iron-containing pellets are sent into a rotary kiln from the kiln tail and subjected to pre-reduction treatment sequentially through a drying section, a preheating section, a plasma reduction section, a reduction roasting section and a slow cooling section, so that a pre-reduction product is obtained. And then the pre-reduction product is sent into a melting furnace for deep reduction treatment to obtain molten iron.

Example 2

As shown in fig. 1 and 3, a process for directly reducing iron-containing pellets based on the external circulation of hot air of a rotary kiln-melting furnace comprises the following steps:

1) According to the trend of the materials, the iron-containing pellets are sent into a rotary kiln from the kiln tail and subjected to pre-reduction treatment sequentially through a drying section, a preheating section, a plasma reduction section, a reduction roasting section and a slow cooling section, so that a pre-reduction product is obtained. And then the pre-reduction product is sent into a melting furnace for deep reduction treatment after passing through a vertical shaft, and molten iron is obtained.

2) And conveying the high-temperature gas at the top of the melting separation furnace into a vertical shaft for reforming to obtain reformed gas, and then conveying the reformed gas to a plasma reduction section for participating in the pre-reduction treatment of the iron-containing pellets after plasma activation. And simultaneously pumping the tail gas of the rotary kiln into the vertical shaft, and adjusting the pumping quantity of the tail gas of the rotary kiln according to the real-time temperature change of the materials in the vertical shaft.

Example 3

As shown in fig. 2 and 4, a process for directly reducing iron-containing pellets based on the external circulation of hot air of a rotary kiln-melting furnace comprises the following steps:

1) According to the trend of the materials, the iron-containing pellets are sent into a rotary kiln from the kiln tail and subjected to pre-reduction treatment sequentially through a drying section, a preheating section, a plasma reduction section, a reduction roasting section and a slow cooling section, so that a pre-reduction product is obtained. And then the pre-reduction product is sequentially sent into a melting furnace for deep reduction treatment after passing through a vertical shaft and an ash separation device, so as to obtain molten iron.

2) And conveying the high-temperature gas at the top of the melting separation furnace into a vertical shaft for reforming to obtain reformed gas, and then conveying the reformed gas to a plasma reduction section for participating in the pre-reduction treatment of the iron-containing pellets after plasma activation. And simultaneously pumping the rotary kiln tail gas into an ash separation device, and adjusting the pumping quantity of the rotary kiln tail gas according to the real-time temperature change of smoke dust in the ash separation device. And finally, carrying out plasma activation on tail gas discharged from the ash separation device, and then conveying the tail gas to a plasma reduction section to participate in the pre-reduction treatment of the iron-containing pellets.

Example 4

As shown in fig. 5 to 9, a direct reduction system for iron-containing pellets comprises a rotary kiln 1, a melting furnace 2 and a microwave plasma initiator 3. According to the trend of the materials, the rotary kiln 1 is sequentially provided with a drying section 101, a preheating section 102, a plasma reduction section 103, a reduction roasting section 104 and a slow cooling section 105. The discharge port of the slow cooling section 105 is directly communicated with the feed port of the melting furnace 2 through the vertical shaft 4. Or the discharge port of the slow cooling section 105 is communicated with the feed port of the ash separation device 5 through the vertical shaft 4, and the discharge port of the ash separation device 5 is communicated with the feed port of the melting furnace 2. The microwave plasma exciter 3 is arranged outside the plasma reduction section 103, and an exhaust port of the microwave plasma exciter 3 is communicated with a bottom air inlet of the plasma reduction section 103. An air flow external circulation system is arranged between the melting furnace 2 and the rotary kiln 1.

Example 5

Example 4 is repeated except that the ash separation device 5 comprises a housing 501 and a vibrating screen ash feed mechanism 502. The vibrating screen ash conveying mechanism 502 is arranged in the shell 2501 and is communicated with a feed inlet and a discharge outlet of the shell 501.

Example 6

Example 5 was repeated except that the wind flow external circulation system includes: the top exhaust port of the melting furnace 2 is communicated with the bottom air inlet of the vertical shaft 4 through a first pipeline L1, and the top exhaust port of the vertical shaft 4 is communicated with the air inlet of the microwave plasma exciter 3 through a second pipeline L2.

Example 7

Example 6 was repeated except that the kiln tail of the rotary kiln 1 was communicated with the bottom air inlet of the ash separation device 5 through the third pipe L3, and the top air outlet of the ash separation device 5 was communicated with the air inlet of the microwave plasma initiator 3 through the fourth pipe L4.

Example 8

Example 7 is repeated except that the system further comprises a temperature detection device 6. The temperature detection device 6 is independently arranged in the vertical shaft 4 and the ash separation device 5.

Example 9

Example 8 is repeated except that the device further comprises a burner 106 and a fuel delivery conduit 107. The burner 106 is disposed within the reduction roasting section 104 and is in communication with a fuel delivery conduit 107. The fuel delivery pipe 107 is also communicated with a combustion-supporting air pipe 108 outside the rotary kiln 1.

Example 10

Example 9 was repeated except that a plurality of burners 106 were provided in the reduction roasting section 104, and a plurality of the burners 106 were each in communication with a fuel delivery pipe 107.

Example 11

Embodiment 10 is repeated except that rotary kiln 1 further comprises kiln body air duct mechanism 7, annular rotary slide rail 8, and rotary slide mechanism 9. The annular rotary slide rail 8 is sleeved outside the rotary kiln 1 and is supported by a bracket 801. The wheel end of the rotary sliding mechanism 9 is connected with the annular rotary sliding rail 8, the other end of the rotary sliding mechanism is connected with the outer end of the kiln body air duct mechanism 7, and the inner end of the kiln body air duct mechanism 7 is connected with the kiln wall. Namely, the rotary kiln 1 and the kiln body air duct mechanism 7 can simultaneously rotate on the annular rotary slide rail 8 through the rotary sliding mechanism 9.

Example 12

Embodiment 11 is repeated except that a plurality of annular rotary slide rails 8 are provided on the outside of the rotary kiln 1. Any one annular rotary slide rail 8 is connected with the rotary kiln 1 through a plurality of rotary slide mechanisms 9 and a plurality of kiln body air duct mechanisms 7.

Example 13

Embodiment 12 is repeated except that the kiln body air duct mechanism 7 comprises an air inlet connector 701, a baffle 702, a pull rod 703 and an air inlet 704. An air inlet channel 705 is formed in the kiln body of the rotary kiln 1. One end of the baffle 702 extends into the air inlet channel 705, and the other end of the baffle is communicated with the air inlet connecting piece 701. The air inlet 704 is formed on the air inlet connector 701. One end of the air inlet connecting piece 701, which is far away from the rotary kiln 1, is connected with one end of a pull rod 703, and the other end of the pull rod 703 is connected with a rotary sliding mechanism 9.

Example 14

Embodiment 13 is repeated except that the rotary slide mechanism 9 includes a rotary wheel mount 901, a lateral rotary wheel 902, and a vertical rotary wheel 903. The rotary wheel seat 901 is of a concave groove structure and is meshed with two side edge parts of the annular rotary slide rail 8. Lateral rotating wheels 902 are provided on rotating wheel seats 901 located on the sides of the endless rotating slide rail 8. Vertical rotating wheels 903 are arranged on rotating wheel seats 901 positioned on the outer bottom surface of the annular rotating slide rail 8. The rotating wheel mount 901 is rotatably slidable on an annular rotary slide rail 8 by a side rotating wheel 902 and a vertical rotating wheel 903.

Example 15

Example 14 is repeated except that the rotary kiln 1 further comprises a horizontal sliding mechanism 10. The horizontal sliding mechanism 10 includes a horizontal wheel seat 1001, a horizontal pulley 1002, and a horizontal rail 1003. The horizontal rail 1003 is a groove-shaped rail arranged at the upper end of the bracket 801. The bottom end of the horizontal wheel seat 1001 is mounted in the horizontal track 1003 by a horizontal pulley 1002. The top end of the horizontal wheel seat 1001 is connected to an annular rotary slide rail 8.

Example 16

Example 15 is repeated except that the device further comprises a swing mechanism 11. The swing mechanism 11 includes a swing motor 1101 and a ring gear 1102. The inner ring of the large gear ring 1102 is fixed on the outer wall of the rotary kiln 1, and the outer ring of the large gear ring 1102 is meshed and connected with a transmission gear of the rotary motor 1101.

Claims

1. A direct reduction process of iron-containing pellets based on the external circulation of hot air of a rotary kiln-a melting furnace is characterized in that: the process comprises the following steps:

1) According to the trend of the materials, feeding the iron-containing pellets from the kiln tail into a rotary kiln, and sequentially carrying out pre-reduction treatment on the iron-containing pellets through a drying section, a preheating section, a plasma reduction section, a reduction roasting section and a slow cooling section to obtain a pre-reduction product; then the pre-reduction product is sent into a melting furnace for deep reduction treatment after passing through a vertical shaft or sequentially passing through the vertical shaft and an ash separation device, so as to obtain molten iron;

201 Conveying high-temperature gas at the top of the melting separation furnace into a vertical shaft for reforming to obtain reformed gas, and then conveying the reformed gas to a plasma reduction section for participating in pre-reduction treatment of iron-containing pellets after plasma activation; simultaneously pumping the tail gas of the rotary kiln into a vertical shaft, and adjusting the pumping quantity of the tail gas of the rotary kiln according to the real-time temperature change of materials in the vertical shaft;

in step 201), the extraction amount of the tail gas of the rotary kiln is adjusted according to the real-time temperature change of the materials in the vertical shaft, specifically: setting the temperature of materials in a vertical shaft to be T1+/-C1, wherein the range of C1 is 0-50 ℃; detecting the real-time temperature of the materials in the vertical shaft to be T2 at the temperature of DEG C in real time; then:

When T2 > (T1 + -C1), increasing the extraction amount of the tail gas of the rotary kiln until the real-time temperature of the materials in the vertical shaft returns to the preset temperature (T1 + -C1);

when T2 epsilon (T1 + -C1), maintaining the current process condition unchanged;

2. The process according to claim 1, characterized in that: the temperature of the high-temperature gas discharged from the top of the melting furnace is more than 1400 ℃; and/or

The content of CO in the reformed gas is higher than 30vol%; h ₂ The content of (2) is higher than 2vol%.

3. The process according to claim 2, characterized in that: the temperature of the high-temperature gas discharged from the top of the melting furnace is more than 1500 ℃; and/or

The content of CO in the reformed gas is higher than 35% by volume; h ₂ The content of (2) is higher than 3vol%.

4. A process according to claim 3, characterized in that: the temperature of the high-temperature gas discharged from the top of the melting furnace is more than 1600 ℃; and/or

In the reformed gas, the content of CO is higher than 40vol%; h ₂ The content of (2) is higher than 5vol%.

5. A direct reduction process of iron-containing pellets based on the external circulation of hot air of a rotary kiln-a melting furnace is characterized in that: the process comprises the following steps:

202 Conveying high-temperature gas at the top of the melting separation furnace into a vertical shaft for reforming to obtain reformed gas, and then conveying the reformed gas to a plasma reduction section for participating in pre-reduction treatment of iron-containing pellets after plasma activation; simultaneously pumping the rotary kiln tail gas into an ash separation device, and adjusting the pumping quantity of the rotary kiln tail gas according to the real-time temperature change of smoke dust in the ash separation device; finally, carrying out plasma activation on tail gas discharged from the ash separation device, and then conveying the tail gas to a plasma reduction section to participate in pre-reduction treatment of the iron-containing pellets;

in step 202), the extraction amount of the tail gas of the rotary kiln is regulated according to the real-time temperature change of the smoke dust in the ash separation device, specifically: setting the set temperature of smoke dust in the ash separation device as T3 + -C2, wherein the range of C2 is 0-50 ℃; detecting the real-time temperature of smoke dust in the ash separation device to be T4 and DEG C in real time; then:

When T4 > (T3 + -C2), increasing the extraction amount of the tail gas of the rotary kiln until the real-time temperature of the smoke dust in the ash separation device returns to the preset temperature (T3 + -C2);

when T4 epsilon (T3 + -C2), maintaining the current process condition unchanged;

6. The process according to claim 5, wherein: the temperature of the high-temperature gas discharged from the top of the melting furnace is more than 1400 ℃; and/or

7. The process according to claim 6, wherein: the temperature of the high-temperature gas discharged from the top of the melting furnace is more than 1500 ℃; and/or

8. The process according to claim 7, wherein: the temperature of the high-temperature gas discharged from the top of the melting furnace is more than 1600 ℃; and/or

9. An iron-bearing pellet direct reduction system for use in the process of any one of claims 1-8, characterized by: the system comprises a rotary kiln (1), a melting furnace (2) and a microwave plasma exciter (3); according to the trend of the materials, the rotary kiln (1) is sequentially provided with a drying section (101), a preheating section (102), a plasma reduction section (103), a reduction roasting section (104) and a slow cooling section (105); the discharge hole of the slow cooling section (105) is directly communicated with the feed hole of the melting furnace (2) through a vertical shaft (4); or the discharge port of the slow cooling section (105) is communicated with the feed port of the ash separation device (5) through the vertical shaft (4), and the discharge port of the ash separation device (5) is communicated with the feed port of the melting furnace (2); the microwave plasma exciter (3) is arranged outside the plasma reduction section (103), and an exhaust port of the microwave plasma exciter (3) is communicated with a bottom air inlet of the plasma reduction section (103); an air flow external circulation system is arranged between the melting furnace (2) and the rotary kiln (1); the ash separation device (5) comprises a shell (501) and a vibrating screen ash conveying mechanism (502); the vibrating screen ash conveying mechanism (502) is arranged in the shell barrel (501) and is communicated with a feed inlet and a discharge outlet of the shell barrel (501); the top exhaust port of the melting furnace (2) is communicated with the bottom air inlet of the vertical shaft (4) through a first pipeline (L1), and then the top exhaust port of the vertical shaft (4) is communicated with the air inlet of the microwave plasma exciter (3) through a second pipeline (L2).

10. The system according to claim 9, wherein: the wind flow external circulation system comprises: the kiln tail of the rotary kiln (1) is communicated with a bottom air inlet of a vertical shaft (4) or is communicated with a bottom air inlet of an ash separation device (5) through a third pipeline (L3), and then a top air outlet of the ash separation device (5) is communicated with an air inlet of a microwave plasma exciter (3) through a fourth pipeline (L4).

11. The system according to claim 10, wherein: the system further comprises a temperature detection device (6); the temperature detection device (6) is independently arranged in the vertical shaft (4) and the ash separation device (5).

12. The system according to any one of claims 9-11, wherein: the device also comprises a burner (106) and a fuel delivery pipeline (107); the burner (106) is arranged in the reduction roasting section (104) and is communicated with the fuel conveying pipeline (107); the outside of the rotary kiln (1) is also communicated with a combustion-supporting air pipe (108) on the fuel conveying pipeline (107).

13. The system according to claim 12, wherein: a plurality of burners (106) are arranged in the reduction roasting section (104), and the burners (106) are communicated with a fuel conveying pipeline (107).

14. The system according to any one of claims 9-11, 13, characterized in that: the rotary kiln (1) further comprises a kiln body air duct mechanism (7), an annular rotary slide rail (8) and a rotary sliding mechanism (9); the annular rotary slide rail (8) is sleeved outside the rotary kiln (1) and is supported by a bracket (801); the wheel end of the rotary sliding mechanism (9) is connected with the annular rotary sliding rail (8), the other end of the rotary sliding mechanism is connected with the outer end of the kiln body air duct mechanism (7), and the inner end of the kiln body air duct mechanism (7) is connected with the kiln wall; namely, the rotary kiln (1) and the kiln body air duct mechanism (7) can simultaneously rotate on the annular rotary slide rail (8) through the rotary sliding mechanism (9).

15. The system according to claim 12, wherein: the rotary kiln (1) further comprises a kiln body air duct mechanism (7), an annular rotary slide rail (8) and a rotary sliding mechanism (9); the annular rotary slide rail (8) is sleeved outside the rotary kiln (1) and is supported by a bracket (801); the wheel end of the rotary sliding mechanism (9) is connected with the annular rotary sliding rail (8), the other end of the rotary sliding mechanism is connected with the outer end of the kiln body air duct mechanism (7), and the inner end of the kiln body air duct mechanism (7) is connected with the kiln wall; namely, the rotary kiln (1) and the kiln body air duct mechanism (7) can simultaneously rotate on the annular rotary slide rail (8) through the rotary sliding mechanism (9).

16. The system according to claim 14, wherein: a plurality of annular rotary sliding rails (8) are arranged outside the rotary kiln (1); any one annular rotary slide rail (8) is connected with the rotary kiln (1) through a plurality of rotary sliding mechanisms (9) and a plurality of kiln body air duct mechanisms (7).

17. The system according to claim 15, wherein: a plurality of annular rotary sliding rails (8) are arranged outside the rotary kiln (1); any one annular rotary slide rail (8) is connected with the rotary kiln (1) through a plurality of rotary sliding mechanisms (9) and a plurality of kiln body air duct mechanisms (7).

18. The system according to claim 14, wherein: the kiln body air duct mechanism (7) comprises an air inlet connecting piece (701), a stop valve (702), a pull rod (703) and an air inlet (704); an air inlet channel (705) is formed in the kiln body of the rotary kiln (1); one end of the baffle valve (702) extends into the air inlet channel (705), and the other end of the baffle valve is communicated with the air inlet connecting piece (701); the air inlet (704) is formed in the air inlet connecting piece (701); one end of the air inlet connecting piece (701) far away from the rotary kiln (1) is connected with one end of the pull rod (703), and the other end of the pull rod (703) is connected with the rotary sliding mechanism (9); and/or

The rotary sliding mechanism (9) comprises a rotary wheel seat (901), a lateral rotary wheel (902) and a vertical rotary wheel (903); the rotary wheel seat (901) is of a concave groove structure and is meshed with two side edge parts of the annular rotary slide rail (8); a lateral rotating wheel (902) is arranged on the rotating wheel seat (901) positioned on the side surface of the annular rotating slide rail (8); a vertical rotating wheel (903) is arranged on the rotating wheel seat (901) positioned on the outer bottom surface of the annular rotating slide rail (8); the rotary wheel seat (901) can rotationally slide on the annular rotary slide rail (8) through a lateral rotary wheel (902) and a vertical rotary wheel (903).

19. The system according to any one of claims 15-17, wherein: the kiln body air duct mechanism (7) comprises an air inlet connecting piece (701), a stop valve (702), a pull rod (703) and an air inlet (704); an air inlet channel (705) is formed in the kiln body of the rotary kiln (1); one end of the baffle valve (702) extends into the air inlet channel (705), and the other end of the baffle valve is communicated with the air inlet connecting piece (701); the air inlet (704) is formed in the air inlet connecting piece (701); one end of the air inlet connecting piece (701) far away from the rotary kiln (1) is connected with one end of the pull rod (703), and the other end of the pull rod (703) is connected with the rotary sliding mechanism (9); and/or

20. The system according to claim 18, wherein: the rotary kiln (1) also comprises a horizontal sliding mechanism (10); the horizontal sliding mechanism (10) comprises a horizontal wheel seat (1001), a horizontal pulley (1002) and a horizontal track (1003); the horizontal track (1003) is a groove-shaped track arranged at the upper end of the bracket (801); the bottom end of the horizontal wheel seat (1001) is arranged in the horizontal track (1003) through a horizontal pulley (1002); the top end of the horizontal wheel seat (1001) is connected with an annular rotary slide rail (8); and/or

The device also comprises a slewing mechanism (11); the slewing mechanism (11) comprises a slewing motor (1101) and a large gear ring (1102); the inner ring of the large gear ring (1102) is fixed on the outer wall of the rotary kiln (1), and the outer ring of the large gear ring (1102) is meshed and connected with a transmission gear of the rotary motor (1101).

21. The system according to claim 19, wherein: the rotary kiln (1) also comprises a horizontal sliding mechanism (10); the horizontal sliding mechanism (10) comprises a horizontal wheel seat (1001), a horizontal pulley (1002) and a horizontal track (1003); the horizontal track (1003) is a groove-shaped track arranged at the upper end of the bracket (801); the bottom end of the horizontal wheel seat (1001) is arranged in the horizontal track (1003) through a horizontal pulley (1002); the top end of the horizontal wheel seat (1001) is connected with an annular rotary slide rail (8); and/or