A multi-layer fluidized bed reactor for iron ore fines reduction

Abstract

The utility model relates to non -furnace ironmaking technical field, concretely relates to a kind of multilayer fluidized bed reactor for iron ore powder reduction, multilayer fluidized bed reactor includes from lower to upper sequential connection's gas distribution chamber and at least two layers of fluidized bed, still includes injection gas supply device, the bottom of each layer of fluidized bed is equipped with gas distribution plate, and the fluidized bed between adjacent layer is equipped with discharge pipe;Discharge pipe includes standpipe and cross pipe, or standpipe and horizontal plate;Cross pipe one end is connected with standpipe bottom;Horizontal plate is arranged below standpipe, and gap is left between standpipe and horizontal plate;The upper mouth of standpipe is located in the material layer of upper fluidized bed, passes through the gas distribution plate of upper fluidized bed bottom downwards, and enters the material layer of adjacent lower fluidized bed;Standpipe lower part is equipped with injection port, and injection port is connected with injection gas supply device.The utility model's multilayer fluidized bed bed layer can be through discharge pipe injection and discharge, and the part above standpipe injection port is always full material state, can avoid gas hole phenomenon of discharge pipe.

Description

Technical Field

[0001] This utility model relates to the field of non-blast furnace ironmaking technology, specifically to a multi-layer fluidized bed reactor for iron ore powder reduction. Background Technology

[0002] The fluidized bed gas-based direct reduction technology for iron ore powder is a highly efficient ironmaking process. The principle involves using a gaseous reducing agent (such as carbon monoxide and hydrogen) at a temperature above room temperature but below the ore's melting temperature to react with fluidized iron ore powder in a redox reaction, gradually reducing the iron oxides in the powder to metallic iron. In the fluidized bed, the high-speed gas flow keeps the iron ore particles in a suspended, fluidized state, greatly increasing the contact area and reactivity between the gas and solid phases, thus enabling the reduction reaction to proceed rapidly and efficiently. The process includes raw material pretreatment, reduction reaction, and product processing. First, the iron ore powder undergoes pretreatment such as sieving and drying to ensure its particle size and moisture content meet process requirements. Then, the pretreated iron ore powder is fed into the fluidized bed reactor, simultaneously introducing preheated and purified reducing gas. Inside the fluidized bed, the iron ore powder comes into full contact with the reducing gas and undergoes a reduction reaction to produce directly reduced iron. The reaction product is then cooled, separated, and sieved to obtain the final directly reduced iron product.

[0003] Typical process:

[0004] Finmet process: There are four fluidized bed reactors. The first one is used for preheating, and the other three are used for reduction. The reducing gas is a mixture of fresh hydrogen-rich gas and recycled reduction tail gas. The metallization rate of the product can reach more than 90%.

[0005] HIsmelt's preheater process: The iron ore preheater used in the HIsmelt process is a circulating fluidized bed (CFB) that uses exhaust gas from the molten reduction furnace (SRV) containing thermal energy and chemical energy of H2 and CO to heat the iron ore powder to about 850°C and pre-reduce the iron ore powder.

[0006] Multi-layer fluidized bed: Composed of several layers of gas distribution plates with vents. Iron ore powder flows from top to bottom through the gas distribution plates under gravity via a feed pipe into the lower fluidized bed, while reducing gas flows from bottom to top through the gas distribution plates to fluidize the iron ore powder. Its advantages include high mass and heat transfer efficiency, low heat loss, and compact structure. Its disadvantages include difficulty and low precision in controlling the feed rate as the materials are fed between layers via feed pipes.

[0007] The disadvantages of overflow-type multilayer fluidized bed are: the overflow pipe is prone to blockage or gas leakage, resulting in unstable material feeding and disrupting the fluidization process; because it relies on overflow for material feeding, adjusting the material layer height requires adjusting the height of the overflow port or the diameter of the overflow pipe, making online adjustment impossible during production. (It should be noted that both overflow pipes and feed pipes are used for interlayer material feeding in the fluidized bed, the difference being that the overflow pipe inlet is on the material surface, while the feed pipe inlet is inside the material layer.)

[0008] In existing multi-layer fluidized bed reactors with overflow pipes, valves are typically installed on the overflow pipes to control the material bed height. For example, in the multi-layer fluidized bed reactor disclosed in Chinese patent document CN1962573A (application number 200610144290.2), a particle flow control valve is installed on the overflow pipe, and the material bed height at the overflow pipe inlet is controlled by the valve opening. However, during use, the valve is subject to wear due to particle impact, and replacement is difficult, making it unsuitable for industrial-scale application. Utility Model Content

[0009] The purpose of this invention is to overcome the shortcomings of the prior art and provide a multi-layer fluidized bed reactor for iron ore powder reduction. This addresses the problems of overflow pipes used for material feeding between multi-layer beds, which are prone to blockage or gas leakage, leading to unstable feeding and disrupting fluidization. Furthermore, because the feed relies on overflow, adjusting the material layer height requires adjusting the overflow port height or overflow pipe diameter, making online adjustment impossible during production. Alternatively, adjusting the feed rate via an adjustable valve at the overflow pipe inlet can cause wear and poor sealing as the valve operates within the fluidized bed material layer.

[0010] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0011] A multi-layer fluidized bed reactor for iron ore powder reduction includes a gas distribution chamber and at least two fluidized beds connected sequentially from bottom to top, and also includes an ore feeding system, a blown gas supply device, a reducing gas supply device, and a reduced iron powder silo.

[0012] Each fluidized bed layer is equipped with an air distribution plate at the bottom, and a feed pipe is provided between adjacent fluidized bed layers;

[0013] The feed pipe includes: a vertical pipe and a horizontal pipe, or a vertical pipe and a horizontal plate;

[0014] One end of the horizontal tube is connected to the bottom of the vertical tube. The purpose of this connection is to allow the material to self-lock when no air enters through the nozzle, and to discharge the material when air is injected through the nozzle, thereby controlling the discharge rate through the injection flow rate. Specifically, the vertical and horizontal tubes can be integrally formed, or the horizontal tube can be welded to the vertical tube; this invention does not impose any limitations. The length of the horizontal tube is 1.4 to 1.8 times its diameter. The angle of repose of the iron ore powder is 30 to 40°. When the length of the horizontal tube is 1.4 to 1.8 times its diameter, the included angle between line segment I and line segment II inside the horizontal tube is necessarily smaller than the angle of repose of the iron ore powder. After the iron ore powder falls into the horizontal tube, it can better achieve self-locking when no injection is applied, and better discharge when injection is applied. Here, line segment I refers to the line connecting the highest point of one end face of the horizontal tube and the lowest point of the other end face, and line segment II refers to the line connecting the lowest point of one end face of the horizontal tube and the lowest point of the other end face.

[0015] The horizontal plate is positioned below the vertical pipe, preferably directly below it, with a gap between the vertical pipe and the horizontal plate. This gap ensures material self-locking when no air enters through the nozzle, and allows material to be discharged when air is expelled through the nozzle, thus controlling the discharge rate through the airflow. The gap between the vertical pipe and the horizontal plate is 0.1 to 2 times the diameter of the vertical pipe. If the gap is too small, no material will flow out even when air is introduced; if the gap is too large, the material cannot self-lock, and the flow rate becomes uncontrollable in both cases. Therefore, this invention preferably sets the gap between the vertical pipe and the horizontal plate to 0.1 to 2 times the diameter of the vertical pipe.

[0016] The upper opening of the vertical pipe is located in the material layer of the upper fluidized bed, and it passes downward through the air distribution plate at the bottom of the upper fluidized bed and enters the material layer of the adjacent lower fluidized bed.

[0017] The lower part of the vertical pipe is provided with a blow nozzle, which is connected to the blow air supply device through an air inlet pipe.

[0018] The top fluidized bed is provided with a feed inlet, which is connected to the feeding system, and the feeding system conveys materials into the top fluidized bed through the feed inlet.

[0019] The bottom fluidized bed is provided with a discharge port, which is connected to the reduced iron powder silo. The reduced material is discharged into the reduced iron powder silo through the discharge port.

[0020] The gas distribution chamber is connected to a reducing gas supply device. The reducing gas supply device supplies reducing gas to the multi-layer fluidized bed reactor through the gas distribution chamber.

[0021] This invention, by configuring the feeding pipe as a combination of a vertical pipe and a horizontal pipe or a vertical pipe and a horizontal plate, allows the material to self-lock on the horizontal pipe or horizontal plate during the feeding process. When no air enters the nozzle, the material can be discharged to the adjacent lower fluidized bed. Regardless of whether the material is in a self-locking or discharging state, the part above the vertical pipe nozzle is always full, forming a material column. This avoids gas leakage through the feeding pipe and prevents clogging of the feeding pipe. Therefore, this invention ensures the stability of the feeding process.

[0022] More preferably, a flow regulating valve is provided on the air supply pipe between the blowing gas supply device and the fluidized bed.

[0023] This invention adjusts the air intake of the spray nozzle by setting a flow regulating valve outside the fluidized bed, thereby adjusting the feeding rate of the feed pipe and realizing online adjustment of the material layer height. It also avoids a series of problems such as wear and valve sealing failure that exist when the valve is working in the fluidized bed material layer.

[0024] Furthermore, when the feed pipe is composed of a vertical pipe and a horizontal pipe, the spray nozzle is 0 to 4 times the diameter of the vertical pipe above the axis of the horizontal pipe.

[0025] Furthermore, when the feed pipe is composed of a vertical pipe and a horizontal plate, the spray nozzle is 1 to 4 times the diameter of the vertical pipe above the horizontal plate.

[0026] Furthermore, the horizontal plate is circular, and its size is designed to ensure that the material in the vertical pipe can self-lock on the horizontal plate without inflating the lower feed tube. Therefore, preferably, the dimensions of the horizontal plate must satisfy: D > d, and 0.5 ≤ 2*H / (d+D) ≤ 0.7, where D is the diameter of the horizontal plate, d is the diameter of the vertical pipe, and H is the gap between the vertical pipe and the horizontal plate.

[0027] Furthermore, the vertical pipe has one or more spray nozzles. When there are two or more spray nozzles, the spray nozzles can be set at the same height of the vertical pipe or at different heights. This utility model does not impose any restrictions.

[0028] Furthermore, the bottom of the horizontal tube is provided with a bottom air inlet, which is connected to the blowing gas supply device through an air inlet pipe. The part of the air inlet pipe located between the blowing gas supply device and the fluidized bed is also provided with a flow regulating valve.

[0029] Furthermore, the bottom of the horizontal plate is provided with a bottom air inlet, which is connected to the blowing gas supply device through an air inlet pipe. The part of the air inlet pipe located between the blowing gas supply device and the fluidized bed is also provided with a flow regulating valve.

[0030] By setting air inlets at the bottom of horizontal pipes and horizontal plates, materials can flow more effectively.

[0031] Furthermore, the horizontal tubes can be set horizontally or at an angle.

[0032] Furthermore, the vertical pipe and the horizontal plate are connected by a connecting rod.

[0033] Furthermore, the top fluidized bed is provided with an air outlet, which is used to discharge the reducing gas that has passed through the top fluidized bed material layer.

[0034] Furthermore, the top fluidized bed is also equipped with a cyclone dust collector, and the exhaust pipe of the cyclone dust collector is connected to the air outlet.

[0035] Furthermore, the number of fluidized bed layers in the multi-layer fluidized bed reactor is 2 to 11; preferably, the number of fluidized bed layers in the multi-layer fluidized bed reactor is 3 to 5.

[0036] Furthermore, each fluidized bed layer is shaped like a cylinder or a frustum.

[0037] Furthermore, the gas used in the injection gas supply device is selected from at least one of N2, CO2, or coal gas.

[0038] The beneficial effects of this utility model are as follows:

[0039] The multi-layer fluidized bed reactor for iron ore powder reduction provided by this utility model has an online adjustment of the feeding speed between the bed layers, a stable and controllable material layer, and no issues such as feed pipe cross-flow or blockage. The equipment is simple and flexible in adjustment. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the multi-layer fluidized bed reactor for iron ore powder reduction provided in Example 1;

[0041] Figure 2 This is a schematic diagram of the structure of the multi-layer fluidized bed reactor for iron ore powder reduction provided in Example 2.

[0042] Among them, 1-multi-layer fluidized bed reactor, 2-air outlet, 3-cyclone dust collector, 4-material layer, 5-discharge outlet, 6-feeding pipe, 7-vertical pipe, 8-horizontal pipe, 9-gas distribution chamber, 10-gas distribution plate, 11-reducing gas inlet pipe, 12-feeding system, 13-feeding pipe, 14-feed inlet, 15-purge nozzle, 16-flow regulating valve, 17-purge gas supply device, 18-horizontal plate, 19-reduced iron powder bin, 20-reducing gas supply device, 21-gas filling pipe, 22-fluidized bed sidewall. Detailed Implementation

[0043] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0044] Example 1

[0045] The following is an appendix Figure 1 For reference, the implementation of this patent is described in detail so that those skilled in the art can easily implement it. This patent may be embodied in many different forms and is not limited to this description.

[0046] Raw materials used: iron ore powder, iron content: ≥50%, particle size: ≤8mm.

[0047] The reducing gas used is high-temperature coal gas produced by the molten reduction furnace, whose main reducing gases are CO and H2.

[0048] The multi-layer fluidized bed is selected as a frustum cone shape, and the diameter of the multi-layer fluidized bed is 8m at the air distribution plate 10; the feed pipe includes a vertical pipe 7 and a horizontal pipe 8, the diameter of the vertical pipe 7 is 400mm, the diameter of the horizontal pipe 8 is 400mm, and the length of the horizontal pipe is 700mm.

[0049] The multi-layer fluidized bed reactor has a production capacity of 300 t / h for reduced iron powder.

[0050] The multi-layer fluidized bed reactor 1 for reducing iron ore powder includes: three fluidized bed layers (upper, middle, and lower) from top to bottom, and a gas distribution chamber 9 located at the bottom of the lower fluidized bed. Each fluidized bed layer is equipped with a gas distribution plate 10 at its bottom. The multi-layer fluidized bed reactor 1 also includes an ore feeding system 12, a blown gas supply device 17, a reduced iron powder silo 19, and a reducing gas supply device 20.

[0051] The upper fluidized bed includes an air outlet 2, a feed inlet 14, and a built-in cyclone dust collector 3. The feeding system 12 is connected to the feed inlet 14 through a feed pipe 13, and the exhaust pipe of the cyclone dust collector 3 is connected to the air outlet 2.

[0052] A feed pipe 6 is provided between the upper fluidized bed and the middle fluidized bed. The upper end of the feed pipe 6 is located within the material layer 4 of the upper fluidized bed, and the lower end is located within the material layer 4 of the middle fluidized bed. A feed pipe 6 is also provided between the middle fluidized bed and the lower fluidized bed. The upper end of the feed pipe 6 is located within the material layer 4 of the middle fluidized bed, and the lower end is located within the material layer 4 of the lower fluidized bed.

[0053] The vertical pipe 7 and horizontal pipe 8 of the feed pipe 6 are welded together and connected. The vertical pipe 7 of the feed pipe 6 between the upper fluidized bed and the middle fluidized bed passes through the air distribution plate 10 of the upper fluidized bed, and the vertical pipe 7 of the feed pipe 6 between the middle fluidized bed and the lower fluidized bed passes through the air distribution plate 10 of the middle fluidized bed. The outer wall of the vertical pipe 7 and the air distribution plate 10 are welded together. The lower part of the vertical pipe 7 is provided with a spray nozzle 15, which is located 800mm above the axis of the horizontal pipe 8. The spray gas supply device 17 is connected to the spray nozzle 15 through the air filling pipe 21 passing through the fluidized bed side wall 22. A sealing element is provided at the connection between the air filling pipe 21 and the fluidized bed side wall 22. A flow regulating valve 16 is provided on the air filling pipe 21 between the spray gas supply device 17 and the fluidized bed side wall 22.

[0054] The lower fluidized bed has a discharge port 5 on its fluidized bed sidewall 22, which is connected to the reduced iron powder silo 19.

[0055] The gas distribution chamber 9 is equipped with a reducing gas inlet pipe 11, which is connected to the reducing gas supply device 20.

[0056] The process of reducing iron ore powder using the multi-layer fluidized bed reactor 1 in this embodiment is as follows:

[0057] (1) Feeding:

[0058] In this embodiment, the feeding is continuous. Iron ore powder is fed into the upper fluidized bed of the multi-layer fluidized bed reactor 1 through the feeding system 12, the feeding pipe 13 and the inlet 14, and a material layer 4 is formed in the upper fluidized bed.

[0059] (2) Discharge between fluidized bed layers:

[0060] The discharge direction of iron ore powder in the fluidized bed layers is from the upper fluidized bed to the adjacent lower fluidized bed. In this embodiment, the discharge method from the upper fluidized bed to the middle fluidized bed is as follows: the upper opening of the feed pipe 6 is in the material layer 4. The iron ore powder enters the upper opening of the feed pipe 6, falls along the vertical pipe 7, and enters the horizontal pipe 8. When the injection port 15 does not introduce air, the angle of accumulation of the iron ore powder in the horizontal pipe 8 is 30° to 40°. The iron ore powder is self-locked in the horizontal pipe 8 and will not be automatically discharged. The feed pipe 6 is in a full state, forming a material column. Due to the effect of the material column, the upward flow of gas through the feed pipe 6 is restricted, so the feed pipe 6 will not be perforated.

[0061] Nitrogen is supplied by the blowing gas supply device 17. The nitrogen is blown into the feed pipe 6 through the flow regulating valve 16, the air filling pipe 21, and the blowing port 15 at the bottom of the vertical pipe 7. The nitrogen loosens and fluidizes the iron ore powder in the feed pipe 6, causing the iron ore powder to be discharged along the horizontal pipe 8, forming the material layer 4 of the next fluidized bed.

[0062] The nitrogen intake is adjusted by the flow regulating valve 16. Increasing the nitrogen intake increases the discharge volume through the feed pipe 6, while decreasing the nitrogen intake decreases the discharge volume through the feed pipe 6. In this embodiment, the relationship between the intake and discharge volumes is shown in the table below.

[0063] Table 1 Relationship between air intake and discharge volume

[0064]

[0065] By adjusting the nitrogen inlet flow rate, and thus the discharge rate (discharge speed) of the feed pipe 6, the height of the material layer 4 can be adjusted online, thereby achieving stable operation of the multi-layer fluidized bed reactor 1.

[0066] Specifically, the process of adjusting the height of the material layer 4 is as follows: Iron ore powder is fed into the upper fluidized bed of the multi-layer fluidized bed reactor 1 through the feeding system 12, the feeding pipe 13, and the inlet 14, forming material layer 4 in the upper fluidized bed; if the resistance of material layer 4 is 30 kPa, the corresponding height of material layer 4 is 2000 mm, and the resistance fluctuates by ±2 kPa during production; when the detected resistance of material layer is greater than 32 kPa, the air flow of the downward feed pipe 6 is increased to increase the discharge volume so that the resistance of material layer reaches 30 kPa; when the detected resistance of material layer is less than 28 kPa, the air flow of the downward feed pipe 6 is reduced to decrease the discharge volume so that the resistance of material layer reaches 30 kPa.

[0067] When gas is continuously introduced into the feed pipe 6 using the blowing gas supply device 17, the iron ore powder is continuously fed; when gas is intermittently introduced into the feed pipe 6 using the blowing gas supply device 17, the iron ore powder is intermittently fed.

[0068] The discharge process from the intermediate fluidized bed to the lower fluidized bed is the same as the process described above, and will not be repeated here.

[0069] (3) Introducing high-temperature coal gas for the reduction process:

[0070] The reducing gas supply device 20 (in this embodiment, a molten reduction furnace) supplies high-temperature coal gas at 850°C and 200 kPa. Before the fluidized bed is put into operation, a pre-bed layer is prepared for each fluidized bed layer, and then the high-temperature coal gas is introduced. The high-temperature coal gas enters the gas distribution chamber 9 from the reducing gas inlet pipe 11, and then enters the lower fluidized bed through the gas distribution plate 10 at the bottom of the lower fluidized bed. The high-temperature coal gas heats the iron ore powder in the material layer 4 of the lower fluidized bed. The CO and H2 in the coal gas react with the iron ore powder to reduce it, and the reduction degree reaches >10% and <100%. The reduced iron ore powder is discharged into the reduced iron powder silo 19 through the discharge port 5.

[0071] The gas rises through the lower fluidized bed material layer 4 and enters the middle fluidized bed material layer 4 through the gas distribution plate 10 at the bottom of the middle fluidized bed. The gas undergoes heat exchange and reduction reaction with the iron ore powder in the middle fluidized bed material layer 4. The reduced iron ore powder is discharged into the lower fluidized bed material layer 4 through the feed pipe 6 between the middle fluidized bed and the lower fluidized bed.

[0072] The gas rises through the material layer 4 of the middle fluidized bed and enters the material layer 4 of the upper fluidized bed through the gas distribution plate 10 at the bottom of the upper fluidized bed. The gas undergoes heat exchange and reduction reaction with the iron ore powder in the material layer 4 of the upper fluidized bed. The reduced iron ore powder is discharged into the material layer 4 of the middle fluidized bed through the feed pipe 6 between the upper and middle fluidized beds.

[0073] After passing through the upper fluidized bed material layer 4, the gas rises and is partially recovered by the built-in cyclone dust collector 3. The recovered fine iron ore powder is returned to the upper fluidized bed material layer 4. The gas that has undergone coarse dust removal is discharged from the multi-layer fluidized bed reactor 1 through the gas outlet 2. After further treatment, it can be recycled or used as fuel gas.

[0074] Among them, when the high-temperature coal gas at 850℃ and 200kPa from the reducing gas supply device 20 passes through the lower, middle and upper layers of the multi-layer fluidized bed 1, the reaction equation for the reduction reaction between CO and H2 in the coal gas and iron oxides in the bed at high temperature is as follows:

[0075] The following reactions mainly occur in the lower layer: FeO + CO = Fe + CO2, FeO + H2 = Fe + H2O; Gas inlet temperature: 850℃;

[0076] The following reactions mainly occur in the middle layer: Fe3O4 + CO = FeO + CO2, Fe3O4 + H2 = FeO + H2O; Gas inlet temperature: 780℃;

[0077] The upper layer is mainly used for heating iron ore powder and carrying out the following reactions: Fe2O3+CO=Fe3O4+CO2, Fe3O4+H2=FeO+H2O. Gas inlet temperature: 680℃, gas outlet temperature: 450℃.

[0078] The reduction process of iron oxides is a top-down, step-by-step reduction. During the bottom-up, step-by-step reduction of coal gas, the CO and H2 content in the coal gas gradually decreases, while the CO2 and H2O content gradually increases. The reducing power of the coal gas weakens, and the coal gas temperature gradually decreases.

[0079] Example 2

[0080] The following is an appendix Figure 2 For reference

[0081] Raw materials used: iron ore powder, iron content: ≥60%, particle size: ≤8mm.

[0082] The reducing gas used is high-temperature coal gas produced by the molten reduction furnace, whose main reducing gases are CO and H2.

[0083] The diameter of the multi-layer fluidized bed is as follows: the diameter of the air distribution plate 10 is 6m, the diameter of the vertical pipe 7 is 300mm, the distance between the horizontal plate 18 and the vertical pipe is 240mm, the shape of the horizontal plate 18 is circular and the diameter is 600mm, and the position of the spray nozzle 15 is 600mm above the horizontal plate 18.

[0084] The multi-layer fluidized bed reactor has a production capacity of 160 t / h for reduced iron powder.

[0085] The difference between this multi-layer fluidized bed reactor 1 and Example 1 is that the feed pipe 6 is composed of a vertical pipe 7 and a horizontal plate 18, with the horizontal plate 18 located directly below the vertical pipe 7. The vertical pipe 7 and the horizontal plate 18 are welded together by a connecting rod, and there is a gap between the lower end of the vertical pipe 7 and the horizontal plate 18.

[0086] The iron ore powder reduction process is carried out using the multi-layer fluidized bed reactor 1 in this embodiment:

[0087] (1) Feeding: Same as in Example 1.

[0088] (2) Discharge between fluidized bed layers:

[0089] The discharge direction of iron ore powder in the fluidized bed layers is from the upper fluidized bed to the adjacent lower fluidized bed. In this embodiment, the discharge method from the upper fluidized bed to the middle fluidized bed is as follows: the upper opening of the feed pipe 6 is in the material layer 4. The iron ore powder enters the upper opening of the feed pipe 6, falls down along the lower vertical pipe 7, and lands on the horizontal plate 18. When the injection port 15 is not receiving air, the angle of accumulation of the iron ore powder on the horizontal plate 18 is 30°~40°. The iron ore powder is self-locked on the horizontal plate 18 and will not be automatically discharged. The feed pipe 6 is in a full state, forming a material column. Due to the effect of the material column, the gas will not flow upward through the feed pipe 6, so the feed pipe 6 will not be perforated.

[0090] Nitrogen is supplied by the blowing gas supply device 17. The nitrogen is blown into the feed pipe 6 through the flow regulating valve 16, the air filling pipe 21, and the blowing port 15 at the bottom of the vertical pipe 7. The nitrogen loosens the iron ore powder in the feed pipe 6, and the iron ore powder is discharged along the gap between the horizontal plate 18 and the vertical pipe 7 to form the material layer 4 of the next fluidized bed.

[0091] The nitrogen intake is adjusted by the flow regulating valve 16. When the nitrogen intake increases, the discharge volume of the feed pipe 6 increases; when the nitrogen intake decreases, the discharge volume of the feed pipe 6 decreases.

[0092] The nitrogen inlet flow rate is adjusted by the flow regulating valve 16, which in turn adjusts the discharge flow rate of the feed pipe 6. Ultimately, the height of the material layer 4 can be adjusted online, enabling the stable operation of the multi-layer fluidized bed reactor 1.

[0093] When gas is continuously introduced into the feed pipe 6 using the blowing gas supply device 17, the iron ore powder is continuously fed; when gas is intermittently introduced into the feed pipe 6 using the blowing gas supply device 17, the iron ore powder is intermittently fed.

[0094] The discharge process from the intermediate fluidized bed to the lower fluidized bed is the same as the process described above, and will not be repeated here.

[0095] (3) Introducing high-temperature coal gas for the reduction process:

[0096] Same as in Example 1, so it will not be repeated here.

[0097] The preferred embodiments of this utility model have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of this utility model without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of this utility model through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A multi-layer fluidized bed reactor for the reduction of iron ore powder, characterized in that, It includes a gas distribution chamber connected sequentially from bottom to top and at least two fluidized beds, as well as a ore feeding system, a blown gas supply device, a reducing gas supply device, and a reduced iron powder silo. Each fluidized bed layer is equipped with an air distribution plate at the bottom, and a feed pipe is provided between adjacent fluidized bed layers; The feed pipe includes: a vertical pipe and a horizontal pipe, or a vertical pipe and a horizontal plate; One end of the horizontal tube is connected to the bottom of the vertical tube, and the length of the horizontal tube is 1.4 to 1.8 times the diameter of the horizontal tube. The horizontal plate is set below the vertical pipe, and a gap is left between the vertical pipe and the horizontal plate. The gap between the vertical pipe and the horizontal plate is 0.1 to 2 times the diameter of the vertical pipe. The upper opening of the vertical pipe is located in the material layer of the upper fluidized bed, and it passes downward through the air distribution plate at the bottom of the upper fluidized bed and enters the material layer of the adjacent lower fluidized bed. The lower part of the vertical pipe is provided with a blow nozzle, which is connected to the blow air supply device through an air inlet pipe; The top fluidized bed is equipped with a feed inlet, which is connected to the ore feeding system; The bottom fluidized bed is provided with a discharge port, which is connected to the reduced iron powder silo. The gas distribution chamber is connected to the reducing gas supply device.

2. The multi-layer fluidized bed reactor as described in claim 1, characterized in that, A flow regulating valve is installed on the air supply pipe between the blown gas supply device and the fluidized bed.

3. The multi-layer fluidized bed reactor as described in claim 1, characterized in that, When the feed pipe is composed of a vertical pipe and a horizontal pipe, the spray nozzle is 0 to 4 times the diameter of the vertical pipe above the axis of the horizontal pipe. When the feed pipe consists of a vertical pipe and a horizontal plate, the nozzle is 1 to 4 times the diameter of the vertical pipe above the horizontal plate.

4. The multi-layer fluidized bed reactor as described in claim 1, characterized in that, The horizontal plate is circular, and its dimensions satisfy: D>d, and 0.5≤2*H / (d+D) ≤0.7, where D is the diameter of the horizontal plate, d is the diameter of the vertical pipe, and H is the gap between the vertical pipe and the horizontal plate.

5. The multi-layer fluidized bed reactor as described in claim 1, characterized in that, It also includes one or more of the following features: The vertical pipe has one or more spray nozzles; The bottom of the horizontal tube is provided with a bottom air inlet, which is connected to the jet air supply device through an air inlet pipe. The bottom of the horizontal plate is provided with a bottom air inlet, which is connected to a jet air supply device through an air inlet pipe.

6. The multi-layer fluidized bed reactor as described in claim 1, characterized in that, Horizontal tubes can be installed horizontally or at an angle; And / or, the vertical pipe and the horizontal plate are connected by a connecting rod.

7. The multi-layer fluidized bed reactor as described in claim 1, characterized in that, An air outlet is provided on the top fluidized bed.

8. The multi-layer fluidized bed reactor as described in claim 7, characterized in that, The top fluidized bed is also equipped with a cyclone dust collector, and the exhaust pipe of the cyclone dust collector is connected to the air outlet.

9. The multi-layer fluidized bed reactor as described in claim 1, characterized in that, The multi-layer fluidized bed reactor has 2 to 11 fluidized bed layers, and / or each fluidized bed layer is cylindrical or frustum-shaped.

10. The multi-layer fluidized bed reactor as described in claim 1, characterized in that, The multi-layer fluidized bed reactor has 3 to 5 bed layers.

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