CN114480767B - Method for preventing iron ore reduction rotary kiln from forming rings - Google Patents
Method for preventing iron ore reduction rotary kiln from forming rings Download PDFInfo
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- CN114480767B CN114480767B CN202210068387.9A CN202210068387A CN114480767B CN 114480767 B CN114480767 B CN 114480767B CN 202210068387 A CN202210068387 A CN 202210068387A CN 114480767 B CN114480767 B CN 114480767B
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/08—Making spongy iron or liquid steel, by direct processes in rotary furnaces
Abstract
The invention provides an anti-looping method for an iron ore reduction rotary kiln, which solves the problems of looping of a kiln body, low roasting temperature and low single kiln productivity in the traditional iron ore rotary kiln reduction process. According to the rotary kiln disclosed by the invention, the gas is heated in a large space for a long time in a diffusion combustion way, flame is not generated in the whole process of the gas, and the temperature of the middle and rear sections of the rotary kiln is reduced; compared with conventional combustion, the diffusion combustion flame is distributed in the high-temperature section hearth space, so that the problem of ring formation of the traditional rotary kiln is solved, the magnetizing roasting capacity of the rotary kiln is improved, and the energy consumption is reduced.
Description
Technical Field
The invention belongs to the technical field of metallurgy and mineral engineering, and relates to an anti-looping method of an iron ore reduction rotary kiln.
Background
At present, the rotary kiln is a thermal equipment for treating iron ore with the granularity of 0-25 mm, and the magnetizing roasting quality and the sorting index of the roasted ore are better than those of a shaft furnace. FIG. 1 is a diagram showing a conventional rotary kiln for magnetizing roasting of iron ore, wherein powdered iron ore is fed into the rotary kiln from an iron ore feed hopper, the iron ore continuously flows from a feed end to a discharge end in the rotary kiln in the rotary process, the iron ore is subjected to heat exchange with high-temperature flue gas flowing in countercurrent in the flowing process to raise the temperature of the iron ore, and a main heat source for heating the iron ore is that coal gas fed from a kiln head burner is premixed and combusted after being fully mixed with air, and a high-temperature flame zone with higher temperature is generated when the coal gas combusts to release heat. In the heating and temperature raising process, firstly drying, removing crystal water and decomposing siderite, then feeding the iron ore with the temperature of more than 650 ℃ into a high-temperature roasting area of the rotary kiln, contacting with granular reducing coal sprayed from a discharge end granular coal spray gun, and carrying out low-temperature hydrogen metallurgy on the iron ore by the reducing coal, so that the iron ore can be roasted well. Because the full-size-fraction iron ore enters the kiln, fine-size-fraction materials are easy to raise and generate dust in the rotary kiln in the process of rotating along with the kiln body, when dust-containing kiln gas contacts high-temperature flame, the fine-size-fraction ore in the kiln gas can generate liquefaction phenomenon due to rapid temperature rise, and liquefied ore particles are adhered to the kiln wall after contacting the kiln wall, so that the rotary kiln finally generates ring formation. Therefore, the looping of the rotary kiln is mainly caused by the existence of high-temperature flame in the kiln.
At present, the technical difficulty affecting the industrialized implementation of the magnetizing roasting technology of the powdery refractory iron ore rotary kiln is kiln body ring formation, and the rotary kiln cannot normally produce because the kiln body ring formation blocks the flow of raw materials and hot air flow in the kiln; the roasting temperature of the rotary kiln is controlled between 650 ℃ and 750 ℃ under the restriction of ring formation of the rotary kiln, so that the rotary kiln has low productivity and high energy consumption per ton of ore, and the magnetizing roasting cost is higher.
The temperature distribution range in the traditional conventional combustion reaction in the rotary kiln is wider, and the chemical reaction changes to change various physical parameters such as surface tension, diffusivity and the like in the process of changing the temperature from low temperature to high temperature, which also leads to the conventional combustion reactionComplex and difficult to control. The highest temperature in the traditional conventional combustion reaction is higher and generally higher than 1800K, and a large amount of NO is easily generated in the combustion X 。
In a rotary kiln, the area surrounded by the combustion front and the burning particles is called a flame, and the premixed combustion flame and the diffusion combustion flame are classified according to the degree of mixing of fuel and air. Premixed combustion flames are flames in which a combustible mixture in which gas and air have been uniformly mixed before entering a combustion chamber burns, and diffusion combustion flames are flames in which gas and air are mixed and burned.
1. Premixed combustion flame
(1) Laminar flame
At present, flame generated by directly reducing iron ore into a rotary kiln burner is premixed combustion flame, after air and coal gas are premixed, the combustible mixture flows into a free space through a common nozzle to form a jet flow, the flow velocity is maximum on the center line of the jet flow section, and then a conical flame is formed after ignition. If the air consumption coefficient of the combustible mixture is greater than 1, only one conical combustion front is formed. In the upstream region of the front, the fresh combustible mixture and in the downstream region the combustion products; on the combustion front, most of the fuel is burned off, and after the combustion front, there is a burn-out section, where the fuel gradually burns completely. If the burnable mixture has an air consumption coefficient of less than 1, an inner cone (which is a stable combustion front) is generated, while an outer cone is also generated. The fuel which is not burnt out on the front surface of the inner cone is sucked into the surrounding space by jet flow to be mixed with the fuel, and the fuel is continuously combusted, so that obvious outer cone flame is formed. FIG. 2 is a shape of a laminar premixed flame.
The laminar premixed flame length increases with increasing airflow velocity and decreases with increasing propagation velocity. Increasing the flow of the mixture increases the flame length at a given burner size and combustible mixture composition, and if the burner flow is the same, the flame burning a combustible mixture having a greater propagation velocity will be shorter than the flame burning a combustible mixture having a lesser propagation velocity. In essence, the length of the laminar premixed flame represents the size of the cone combustion front, and as the flow increases, a larger front is required to burn, and the length naturally increases. The flame length is shorter because smaller combustion fronts are required for combustion of gases with greater combustion propagation speeds.
(2) Turbulent flame
When the combustible mixture is ejected from the nozzle in a turbulent flow, the flame profile created after ignition is not as sharp as laminar, but is also an approximately conical shaped flame. As a result of the turbulent gas particle pulsations, the turbulent combustion front is not a very thin plane like a laminar flow, but rather a thicker one, where the particles (fresh combustible mixture, burning gas and combustion products) are interlaced with each other. Thus, the turbulent flame may be roughly divided into three zones, the center being the unburned combustible mixture, the combustion zone being the visible turbulent combustion front in which most of the combustible gas is burned, and the burn-out zone being the zone where complete combustion is achieved. FIG. 3 is a turbulent premix flame structure.
The length of the turbulent premix flame is related to the airflow velocity, the combustion propagation velocity, and the nozzle size, and as the airflow velocity increases, the flame length increases and as the combustion propagation velocity increases, the flame length becomes smaller. When the burner size becomes larger, if the gas flow speed is not changed, the flow rate must be increased, and thus the flame length will also be increased. Turbulent flame stability is primarily a misfire problem because the airflow velocity has increased above the flashback threshold velocity and flashback problems no longer occur. Turbulent combustion, unlike laminar combustion, relies primarily on the heat source provided by the ignition ring to effect ignition, but must continue to ignite in order for the fuel to burn stably. When the air-gas mixture is turbulently combusted, the mass being combusted or the high-temperature combustion products can be returned to the fresh combustible mixture due to the pulsation of the particles in different directions, and the high Wen Zhidian serves as a heat source for continuous ignition.
2. Diffusion combustion flame
(1) Laminar flame combustion
When the gas and air are respectively introduced into the combustion chamber in laminar flow, laminar flow dispersion combustion can be obtained. In a laminar flame structure formed by concentric jet flows, air-gas mixing is performed in a molecular diffusion mode, and air molecules diffuse to the gas jet flow and gas molecules diffuse to the air jet flow on an interface where two jet flows are contacted. At an interface where the gas is mixed with air at a stoichiometric concentration (i.e., an air consumption factor of 1), the combustible mixture ignites and a combustion front will form at the interface. The combustion products generated on the combustion front spread simultaneously in two opposite directions-the central gas jet and the surrounding air jet. Thus, the laminar flame is significantly divided into four regions: a pure gas zone, a gas plus combustion product zone, an air plus combustion product zone, and a pure air zone. The combustion intensity of such laminar flame is small, and the concentration distribution in the laminar flame is: the concentration of fuel is greatest at the center and then gradually decreases in the radial direction to zero at the flame front; the concentration of oxygen is also zero at the leading surface and gradually diffuses outward to increase to the concentration of oxygen in the surrounding medium. That is, the gas to air ratio is stoichiometric on the flame front and the chemical reaction is instantaneously completed, the overall flame structure being dependent on the diffusion of the gas.
The laminar diffusion flame structure consists of pure air jet, pure gas jet, mixture of gas and combustion products, mixture of air and combustion products, jet boundary and air, and fig. 4 is a laminar diffusion flame structure. The influencing factors of laminar diffusion flame length are: when the fuel composition is fixed, it is mainly dependent on the volume flow of the gas. If the volume flow is fixed, the flame length is irrelevant to the nozzle diameter; if the gas flow rate is fixed, the flame length increases with the diameter; if the diameter is constant, the flame length increases with increasing flow rate, since the length of the diffusion flame is mainly dependent on the time required to complete the mixing process; the greater the flow of gas, the longer it takes for the flow to mix with the air (to reach the stoichiometric ratio), during which time the gas molecules will flow over a longer path, i.e. the longer the flame length; conversely, the smaller the gas flow, the shorter the flame can be in mixed combustion with air in a shorter distance.
(2) Turbulent flame combustion
By increasing the flow rate of the gas and the air, the laminar flame can be transited to the turbulent flame, when the air gas flows in a laminar way, the outline of the flame is regular, when the air flow speed is increased, only the top of the flame is firstly dithered, and along with the continuous increase of the air flow speed, the upper part of the flame becomes the turbulent flame, so that a conversion point exists in the length direction of the flame, and under a certain speed, the flame is converted into turbulent flow from laminar flow. In the case of laminar combustion, the flame length no longer has a significant effect on the flame length with the gas flow velocity, since in the case of turbulent flow the mixing velocity of the gas flow increases with increasing gas flow velocity, and when the gas flow velocity increases (in the case of a constant burner diameter), on the one hand the increase in gas flow increases the flame length and on the other hand the increase in gas mixing velocity shortens the flame, as a result of which both the positive and negative effects make the change in turbulent flame length with the gas flow velocity insignificant.
3. Diffusion combustion
The diffusion combustion is one of diffusion combustion, is low-heat release intensity soft combustion in a low-oxygen atmosphere, and can better realize the double requirements of low pollution and high-efficiency combustion. "dispersion" means "dispersion of points or positions where oxygen molecules and combustible molecules are mixed and reacted", i.e. "flame or reaction points are dispersed in the furnace", "which is combustion in which oxygen molecules and combustible molecules are uniformly dispersed at various positions in the furnace". The combustion characteristics of the dispersion combustion are that the flame brightness is weakened, NO obvious frontal surface exists at the flame edge, the chemical reaction rate is low, the reaction area volume is large, the concentration gradient of reactants is small, NO local high-temperature area exists, the combustion highest temperature is low, the heat flow density is uniform, and the pollutant NO X And the CO emission is obviously reduced, and the noise in the combustion process is extremely low. In the hydrogen metallurgy process of the iron ore in the rotary kiln, the dispersion combustion technology has remarkable energy-saving and environment-friendly characteristics, and has very important significance for enhancing the efficient utilization of energy, improving the air quality, reducing the production funds of enterprises and improving the competitiveness of the enterprises.
For today's enterprises, the environment, resources and energy are the biggest obstacles limiting their rapid development. The dispersion combustion technology is a novel energy-saving and environment-friendly technology, is highly concerned by countries around the world, and is widely popularized and applied. The dispersion combustion technology has been rapidly developed in developed countries such as Europe and America, japan and the like, and has been successfully applied and popularized in smelting furnaces, forging furnaces, protective atmosphere heat treatment furnaces, ceramic heating furnaces, cracking furnaces, direct reduction rotary hearth furnaces and the like. The diffusion combustion technology is developed rapidly although starting at home later. Has been successfully applied to industrial furnaces in the industries of metallurgy, steel, ceramics, textile, building materials, machinery and the like, and has better effect in the aspects of energy conservation and emission reduction.
Disclosure of Invention
The invention provides an iron ore reduction rotary kiln ring-forming prevention method for solving the problem of kiln body ring-forming in the traditional iron ore rotary kiln reduction process, and increasing the roasting temperature of iron ore to 750-850 ℃, thereby improving the magnetizing roasting capacity of the rotary kiln, reducing the energy consumption and providing the iron ore reduction rotary kiln ring-forming prevention method according to the coal gas dispersion combustion mechanism.
The invention relates to an anti-looping method for an iron ore reduction rotary kiln, which is completed by the following equipment and method:
anti-loop device: the rotary kiln comprises an air injection port, a gas injection port and a pellet coal spray pipe which are arranged at the discharge end of the rotary kiln, wherein the distance between the gas injection port and the air injection port is controlled to be 300-800mm, the pellet coal spray pipe is connected with a pellet coal fluidization chamber, the pellet coal fluidization chamber is connected with a pellet coal feeding hopper and a compressed air pipe, an air regulating valve is arranged on the compressed air pipe, and a kiln back fan is arranged on the kiln body of the rotary kiln.
And the iron ore feeding hopper at the feeding end of the rotary kiln is provided with a roasting material discharging outlet at the discharging end.
The air injection port is arranged at the upper part of the gas injection port, and the particle coal spray pipe is arranged at the upper part of the gas injection port.
The kiln back fan is provided with 2-5 kiln back fans, the 1 st kiln back fan is arranged at a position 8-10m away from the discharge end, the 2 nd kiln back fan is arranged at a position 11-13m away from the discharge end, and the 3 rd kiln back fan is arranged at a position 14-16m away from the discharge end; when the kiln body of the rotary kiln is longer, the 4 th kiln back fan and the 5 th kiln back fan are arranged at positions 18-20m and 22-25m away from the discharge end; the air supply quantity of the kiln back fan is set to be reduced from the 1 st kiln back fan to the last kiln back fan in sequence.
The loop-forming prevention method comprises the following steps:
(1) Injecting the fuel of the rotary kiln into the kiln from a gas injection port, and blowing combustion air into the kiln through an air injection port and a compressed air pipe;
(3) In the jet flow process after the gas enters the kiln, the gas is mixed with air blown in by an air injection port and a compressed air pipe while preheating while flowing, and the dispersion combustion of part of the gas is realized by controlling the injected air quantity;
(4) When the residual gas flows to the position of the 1 st kiln back fan along with the combustion products in the kiln, combustion air is supplied into the rotary kiln through the 1 st kiln back fan, and the combustion air and the residual gas flow, are mixed and preheated simultaneously, and the dispersion combustion of part of the gas is realized by controlling the air blowing amount;
(5) And then when the unburned combustible gas in the kiln gas flows to the position of the back fan of the 2 nd kiln along with the kiln gas, the combustion air is fed into the rotary kiln through the back fan of the 2 nd kiln, and the combustion air and the unburned combustible gas are continuously subjected to dispersion combustion, and the above processes are sequentially repeated until the combustible components are completely combusted.
On the basis of the existing rotary kiln reduction structure, the invention adopts a low-temperature dispersion combustion method that coal gas does not generate flame in the combustion process of the rotary kiln in order to solve the problem of ring formation generated in the hydrogen metallurgy process of iron ore. According to the method, an original kiln head burner (a device for mixing and burning coal gas and combustion air in the burner) of a rotary kiln is transformed into a single coal gas injection port, an air injection port is added, air matched by the burner is cut off, meanwhile, 2-5 kiln back fans are additionally arranged on the kiln back of the rotary kiln, normal-temperature air is blown into the middle rear section of the rotary kiln through the kiln back fans, and partial air is injected from the discharge end of the rotary kiln through the air injection port and a compressed air pipe. The fuel required by roasting the rotary kiln material is injected into the rotary kiln from a gas injection port, and after entering the kiln from the kiln head, the gas is mixed with air blown in from an air injection port of the kiln head and a material injection system and preheated at the same time in the jet flow process, and the dispersion combustion of part of the gas is realized by controlling the blowing air quantity; when the residual gas flows to the position of a 1 st kiln back fan in the kiln along with combustion products, part of combustion air is fed into the rotary kiln from the 1 st kiln back fan, and the part of combustion air and combustible gas flowing into the kiln from the front section are mixed and preheated while flowing, so that the dispersion combustion of part of gas is realized by controlling the air quantity of the air; when the unburned combustible gas in the kiln gas flows to the position of the 2 nd kiln back fan along with the kiln gas, part of combustion air is supplied into the rotary kiln from the 2 nd kiln back fan, and the air and the unburned combustible gas are continuously subjected to dispersion combustion; when the rotary kiln is provided with a plurality of kiln back fans, the process can be repeated until the combustible components in the smoke are completely combusted, so that the smoke produced by the rotary kiln is discharged up to the standard. Thus, the gas sprayed into the kiln from the discharge end of the rotary kiln can be subjected to dispersion combustion in a longer region of the middle and rear section of the rotary kiln. As the area of gas combustion in the rotary kiln is enlarged and the combustion speed is reduced, no open flame exists in the whole kiln chamber space, thereby reducing the temperature of the rear area in the rotary kiln.
When the kiln head equipment is arranged as the upper air injection port and the lower air injection port, the temperature gradient of the hearth space is reduced along with the increase of the distance between the air injection port and the upper air injection port, the temperature distribution is more uniform, and the basic characteristics of the dispersion combustion are met, but the excessive increase of the distance possibly causes air jet to be close to the wall surface, so that the combustion stability is affected. Therefore, the interval between the kiln head gas injection port and the air injection port of the rotary kiln is controlled to be 300-800mm.
The invention forms a stable dispersion combustion area at the middle and rear sections of a rotary kiln, wherein the 1 st kiln lee fan equipment is positioned at a position 8-10m away from a discharge end, the 2 nd kiln lee fan equipment is positioned at a position 11-13m away from the discharge end, and the 3 rd kiln lee fan equipment is positioned at a position 14-16m away from the discharge end; when the kiln body of the rotary kiln is longer, the 4 th kiln back fan and the 5 th kiln back fan can be arranged at the positions 18-20m and 22-25m away from the discharge end, so that the dispersion combustion area of the rotary kiln is expanded to a larger range.
According to the conditions that the reduction speed of iron ore in the early reduction stage is high, the amount of combustible gas discharged from a material layer is large, the material temperature is low, the reduction speed of the later reduction stage is low, the amount of combustible gas discharged from the material layer is small, and the material temperature is high in the reduction process of iron ore in the rotary kiln, the method is used for strengthening the heat supply of the iron ore in the early reduction stage, improving the material temperature level, properly controlling the material temperature of the iron ore in the later reduction stage, setting the air supply quantity of a kiln back air blower from a 1 st kiln back air blower to a last kiln back air blower to be sequentially reduced, setting the air supply quantity of the 1 st kiln back air blower to be maximum, setting the air supply quantity of the 2 nd kiln back air blower to be secondary, and sequentially reducing the air supply quantity of a subsequent kiln back air blower.
According to the invention, the original kiln head burner is adopted in the kiln starting and kiln drying processes, the gas and the combustion air are uniformly mixed in the burner and then premixed flame combustion is carried out, when the kiln temperature is raised to above 600-650 ℃, the dispersion combustion is realized for reducing the heat load of a high-temperature zone, the air supply quantity of the kiln head burner is slowly reduced until the air supply quantity of the kiln head burner is completely closed while the air supply quantity of an air inlet and the air supply quantity of a kiln lee machine are increased to completely combust the gas, so that the conversion from premixed flame combustion to dispersion combustion of the gas in the rotary kiln can be realized.
The main technical characteristic of the invention is that the dispersion combustion is adopted in the rotary kiln, and the dispersion combustion completes the reaction in a larger space and longer time, thereby effectively preventing the abrupt increase of the reaction rate and ensuring the low intensity of the combustion reaction. Although the peak temperature in the dispersion combustion is reduced, the temperature and the heat flow of the hearth are uniformly distributed, the temperature fluctuation is small, the average temperature of the hearth is increased instead, and the radiation heat exchange of the hearth is enhanced. In addition, compared with the conventional combustion, the flame intensity of the dispersion combustion is low, a local high-temperature area does not exist, the combustion highest temperature is low, the heat flux density is uniform and the space of a high-temperature section hearth is fully distributed, the problem of ring formation of the rotary kiln caused by the existence of high-temperature flame in the kiln is solved, and the roasting temperature of iron ore is raised to 750-850 ℃, so that the magnetizing roasting capacity of the rotary kiln is improved, the energy consumption is reduced, the application range of low-heat-value fuel is expanded, the quality and the yield of products are improved, and the service life of related equipment is prolonged.
According to the invention, excessive reducing coal is added in the reduction process of iron ore in the rotary kiln, a part of carbon residue remains in the material after the reduction is finished, and when the reduction material is melted at high temperature in the kiln and is adhered to the inner surface of the rotary kiln to form hanging materials, a certain amount of carbon residue is contained in the hanging materials; when the hung material rotates to a kiln chamber space above the material along with the rotary kiln, carbon residue contained in the material burns under the action of high-temperature flue gas in the kiln, the temperature of the hung material around the carbon residue can be increased by heat generated by burning the carbon residue, a thermal stress phenomenon is generated in the hung material due to the difference of local expansion amounts, and the hung material falls when the thermal stress is accumulated to a certain degree.
The invention has the beneficial effects that:
(1) In the iron ore reduction rotary kiln, by arranging a gas injection port and an air injection port at the feeding end of the rotary kiln and arranging 2-5 kiln back fans at the kiln body, heating gas and combustion air are blown into the kiln from different parts of the discharging end of the rotary kiln and the kiln body in a jet flow mode respectively, and air gas is mixed, preheated and combusted in the jet flow process in the kiln, so that the dispersion combustion of the gas in the rotary kiln is realized;
(2) The gas is in dispersion combustion in the rotary kiln to complete the reaction in a larger space and longer time, so that the sudden increase of the reaction rate is effectively prevented, the low intensity of the combustion reaction is ensured, flame is not generated in the combustion reaction process, the temperature of the middle and rear sections of the rotary kiln is reduced, and the ring formation of the rotary kiln is prevented;
(3) The temperature and heat flow distribution of the gas dispersion combustion hearth are uniform, the temperature fluctuation is small, the average temperature of the hearth is increased, the radiation heat exchange of the hearth is enhanced, compared with the conventional combustion, the flame intensity of the dispersion combustion is low, no local high-temperature area exists, the combustion highest temperature is low, the heat flow density is uniform and the hearth space of the high-temperature section is fully distributed, the problem of looping of the rotary kiln is solved, the application range of low-heat-value fuel is expanded, the quality and the yield of products are improved, and the service life of related equipment is prolonged.
Drawings
FIG. 1 is a diagram of a conventional rotary kiln for magnetizing roasting iron ore;
FIG. 2 is a shape of a laminar premixed flame;
FIG. 3 is a turbulent premix flame structure;
FIG. 4 is a laminar diffusion flame configuration;
FIG. 5 is a schematic view of the structure of the device of the present invention;
in the figure: the kiln comprises a rotary kiln, a kiln head cover at a 2-feeding end, a 3-feeding hopper, a kiln head cover at a 4-discharging end, a 5-kiln head burner, a 6-particle coal spray gun, a 7-roasting material outlet, an 8-flue gas outlet, a 9-refractory material, a 10-roasting material, an 11-air injection inlet, a 12-gas injection inlet, a 13-particle coal spray pipe, a 14-particle coal fluidization chamber, a 15-particle coal feeding hopper, a 16-compressed air pipe, a 17-air regulating valve and an 18-kiln lee fan.
Detailed Description
The method for preventing the iron ore reduction rotary kiln from forming rings is further described below with reference to the accompanying drawings.
The invention relates to an anti-looping method for an iron ore reduction rotary kiln, which is completed by the following equipment and method:
anti-loop device: as shown in fig. 5, the rotary kiln comprises an air injection port 11, a coal gas injection port 12 and a pellet coal spray pipe 13 which are arranged at the discharge end of the rotary kiln 1, the distance between the coal gas injection port 12 and the air injection port 11 is controlled to be 300-800mm, the pellet coal spray pipe 13 is connected with a pellet coal fluidization chamber 14, the pellet coal fluidization chamber 14 is connected with a pellet coal feeding hopper 15 and a compressed air pipe 16, an air regulating valve 17 is arranged on the compressed air pipe 16, and a kiln lee fan 18 is arranged on the kiln body of the rotary kiln 1. The air injection port 11 is provided at an upper portion of the gas injection port 12, and the pellet coal injection pipe 13 is provided at an upper portion of the gas injection port 12.
The kiln back fan 18 is provided with 2-5 kiln back fans, the 1 st kiln back fan is arranged at a position 8-10m away from the discharge end, the 2 nd kiln back fan is arranged at a position 11-13m away from the discharge end, and the 3 rd kiln back fan is arranged at a position 14-16m away from the discharge end; when the kiln body of the rotary kiln 1 is longer, the 4 th kiln back fan and the 5 th kiln back fan are arranged at positions 18-20m and 22-25m away from the discharge end; the air supply quantity of the kiln back fan 18 is set to be reduced from the 1 st kiln back fan to the last kiln back fan in sequence. The iron ore feeding hopper 3 at the feeding end of the rotary kiln 1 is provided with a roasting material discharging outlet 7 at the discharging end.
The loop-forming prevention method comprises the following steps:
(1) Injecting rotary kiln fuel into the kiln from a gas injection port 12, and blowing combustion air into the kiln through an air injection port 11 and a compressed air pipe 16;
(3) In the jet flow process after the gas enters the kiln, the gas is mixed with air blown in by the air spraying opening 11 and the compressed air pipe 16 while preheating while flowing, and the diffusion combustion of partial gas is realized by controlling the spraying air quantity;
(4) When the residual gas flows to the position of the 1 st kiln back fan along with the combustion products in the kiln, combustion air is supplied into the rotary kiln through the 1 st kiln back fan, and the combustion air and the residual gas flow, are mixed and preheated simultaneously, and the dispersion combustion of part of the gas is realized by controlling the air blowing amount;
(5) And then when the unburned combustible gas in the kiln gas flows to the position of the back fan of the 2 nd kiln along with the kiln gas, the combustion air is fed into the rotary kiln through the back fan of the 2 nd kiln, and the combustion air and the unburned combustible gas are continuously subjected to dispersion combustion, and the above processes are sequentially repeated until the combustible components are completely combusted. The air jet zone, gas jet zone, combustion zone, recirculation zone and burnout zone formed in the rotary kiln are shown in figure 5.
Claims (3)
1. An anti-looping method for an iron ore reduction rotary kiln is completed by the following equipment and method:
anti-loop device: the rotary kiln comprises an air injection port, a gas injection port and a pellet coal spray pipe which are arranged at the discharge end of the rotary kiln, wherein the distance between the gas injection port and the air injection port is controlled to be 300-800mm, the pellet coal spray pipe is connected with a pellet coal fluidization chamber, the pellet coal fluidization chamber is connected with a pellet coal feeding hopper and a compressed air pipe, an air regulating valve is arranged on the compressed air pipe, and a kiln back fan is arranged on the kiln body of the rotary kiln; the air injection port is arranged at the upper part of the gas injection port;
2-5 kiln back fans are arranged, the 1 st kiln back fan is arranged at a position 8-10m away from the discharge end, the 2 nd kiln back fan is arranged at a position 11-13m away from the discharge end, and the 3 rd kiln back fan is arranged at a position 14-16m away from the discharge end; when the kiln body of the rotary kiln is longer, the 4 th kiln back fan and the 5 th kiln back fan are arranged at positions 18-20m and 22-25m away from the discharge end; the air supply quantity of the kiln back fan is set to be reduced from the 1 st kiln back fan to the last kiln back fan in turn;
the loop-forming prevention method comprises the following steps:
(1) Injecting the fuel of the rotary kiln into the kiln from a gas injection port, and blowing combustion air into the kiln through an air injection port and a compressed air pipe;
(3) In the jet flow process after the gas enters the kiln, the gas is mixed with air blown in by an air injection port and a compressed air pipe while preheating while flowing, and the dispersion combustion of part of the gas is realized by controlling the injected air quantity;
(4) When the residual gas flows to the position of the 1 st kiln back fan along with the combustion products in the kiln, combustion air is supplied into the rotary kiln through the 1 st kiln back fan, and the combustion air and the residual gas flow, are mixed and preheated simultaneously, and the dispersion combustion of part of the gas is realized by controlling the air blowing amount;
(5) And then when the unburned combustible gas in the kiln gas flows to the position of the back fan of the 2 nd kiln along with the kiln gas, the combustion air is fed into the rotary kiln through the back fan of the 2 nd kiln, and the combustion air and the unburned combustible gas are continuously subjected to dispersion combustion, and the above processes are sequentially repeated until the combustible components are completely combusted.
2. The method for preventing looping of an iron ore reduction rotary kiln according to claim 1, wherein the method comprises the following steps: the pellet coal spray pipe is arranged at the upper part of the coal gas injection port.
3. The method for preventing looping of an iron ore reduction rotary kiln according to claim 1, wherein the method comprises the following steps: and the iron ore feeding hopper at the feeding end of the rotary kiln is provided with a roasting material discharging outlet at the discharging end.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210068387.9A CN114480767B (en) | 2022-01-20 | 2022-01-20 | Method for preventing iron ore reduction rotary kiln from forming rings |
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| CN202210068387.9A CN114480767B (en) | 2022-01-20 | 2022-01-20 | Method for preventing iron ore reduction rotary kiln from forming rings |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US4273314A (en) * | 1979-06-22 | 1981-06-16 | The Direct Reduction Corporation | Direct reduction rotary kiln with improved air injection |
| US4387654A (en) * | 1980-05-05 | 1983-06-14 | Coen Company, Inc. | Method for firing a rotary kiln with pulverized solid fuel |
| CN103276194A (en) * | 2013-05-06 | 2013-09-04 | 酒泉钢铁(集团)有限责任公司 | Ring formation resistant magnetizing roasting process for difficultly separated iron ore rotary kiln |
| CN107560740A (en) * | 2017-09-22 | 2018-01-09 | 新中天环保股份有限公司 | A kind of kiln temperature detection method |
| CN108624751B (en) * | 2018-06-15 | 2023-12-15 | 甘肃酒钢集团宏兴钢铁股份有限公司 | Refractory iron ore fluidization heating low-temperature hydrogen reduction device |
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