A device and method for detecting the metallization rate of hydrogen-based shaft furnace direct reduction iron

Abstract

The present invention discloses a device and method for detecting the metallization rate of direct reduced iron in a hydrogen-based vertical furnace, which includes a DRI cooler, a detection device, a diverter valve, a 1# high-pressure discharge tank and a 2# high-pressure discharge tank; the DRI cooler is connected to the inlet of the diverter valve through a pipeline, and the two outlets of the diverter valve are respectively connected to the 1# high-pressure discharge tank and the 2# high-pressure discharge tank; the detection device includes an excitation coil and a receiving coil; the excitation coil and the receiving coil are arranged inside the DRI cooler; the excitation coil and the receiving coil are arranged front and back according to the flow direction of the direct reduced iron; the excitation coil is connected to alternating current. The device and method can quickly detect whether the direct reduced iron reaches a qualified metallization rate through the detection device, separate qualified DRI from unqualified DRI, and are used to guide the production of hydrogen-based vertical furnaces, ensure the quality of DRI products, and improve production efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of direct reduction ironmaking, in particular to a device and method for detecting the metallization rate of hydrogen-based vertical furnace direct reduction iron. Background Art

[0002] Hydrogen metallurgical shaft furnace refers to a gas-based shaft furnace direct reduction ironmaking process that uses hydrogen-rich gas or pure hydrogen as reducing gas to reduce iron ore and pellets to produce direct reduced iron (DRI). It is a short process. It reduces the use of carbon from the source. Compared with the traditional "blast furnace + converter" long process of the same scale, the CO2 emission reduction rate is more than 70%, which greatly reduces the generation and emission of pollutants.

[0003] It was found in the hydrogen-based vertical furnace ironmaking process that unqualified DRI would be produced in two situations. First, when the hydrogen-based vertical furnace system was started up and production resumed, because the interior of the hydrogen-based vertical furnace was in a heating stage, the temperature required for full reduction of the oxidized pellets was not reached, and the metallization rate did not meet the standard, resulting in unqualified DRI being produced.

[0004] Second, when the production process exceeds the safe operating range, mechanical equipment fails, the system itself fails, or energy is interrupted, in order to protect the safety of personnel and process equipment, a safety interlock shutdown will be triggered, causing the temperature in the hydrogen-based vertical furnace to drop, affecting the reduction of pellets, and ultimately reducing the direct reduced iron metallization rate, producing unqualified DRI.

[0005] In order to ensure the quality of DRI products and meet the requirements of subsequent steelmaking, it is necessary to separate qualified and unqualified direct reduced iron (DRI) products from each other and store them separately. The next use will be determined based on whether the metallization rate is qualified. Therefore, how to separate qualified DRI from unqualified DRI is a major problem in the actual production of vertical furnaces.

[0006] The following two methods are usually used in hydrogen-based vertical furnace production sites to separate qualified DRI from unqualified DRI.

[0007] Predictive discharge method: According to the charging time, startup time, shutdown time, vertical furnace reactor volume and discharge speed, the discharge time of unqualified DRI is predicted, so as to separate the unqualified products from the qualified products. This method has limitations and relies too much on the experience of operators. It can only judge the approximate discharge time of unqualified DRI, and there are errors in human judgment, which may cause qualified products to be mixed with unqualified products, and the quality of direct reduced iron cannot be guaranteed, which is not conducive to subsequent steelmaking operations.

[0008] Chemical testing method: Taking an appropriate amount of direct reduced iron for chemical testing can accurately determine the metallization rate and its chemical composition, and determine whether it is qualified. However, chemical testing takes several hours and has a lag. Therefore, relying on chemical testing is not fast enough and delays production judgment. It is usually used as a means of verification of DRI's daily chemical analysis and predictive discharge method.

[0009] Therefore, there is an urgent need for a detection device and method that can quickly determine whether direct reduced iron has reached a qualified metallization rate and separate qualified DRI from unqualified DRI. Summary of the invention

[0010] The technical problem to be solved by the present invention is to provide a device for detecting the metallization rate of hydrogen-based shaft furnace direct reduced iron for rapid determination of the metallization rate; the present invention also provides a method for detecting the metallization rate of hydrogen-based shaft furnace direct reduced iron.

[0011] In order to solve the above technical problems, the technical solution adopted by the device of the present invention is: it includes a DRI cooler, a detection device, a diverter valve, a 1# high-pressure discharge tank and a 2# high-pressure discharge tank; the DRI cooler is connected to the inlet of the diverter valve through a pipeline, and the two outlets of the diverter valve are respectively connected to the 1# high-pressure discharge tank and the 2# high-pressure discharge tank; the detection device includes an excitation coil and a receiving coil; the excitation coil and the receiving coil are arranged inside the DRI cooler; the excitation coil and the receiving coil are arranged front and back according to the flow direction of direct reduced iron; the excitation coil is connected to alternating current.

[0012] Furthermore, the excitation coil and the receiving coil are fixedly mounted on the inner wall of the cone portion at the upper portion of the discharge port of the DRI cooler.

[0013] Furthermore, the detection device also includes a voltage sensor and a controller; the voltage sensor is connected to the receiving coil, and the voltage sensor is connected to the controller signal; the controller controls the diverter valve to connect to the 1# high-pressure discharge tank or the 2# high-pressure discharge tank.

[0014] The method of the present invention adopts the above-mentioned device, and the detection device controls the diverter valve to guide the qualified DRI and unqualified DRI to be discharged into different high-pressure discharge tanks according to the voltage change of the receiving coil.

[0015] Furthermore, the following process states are adopted: 1) when the hydrogen-based vertical furnace is in stable production, the detection device is in a closed state, and the diverter valve guides the qualified DRI to be discharged to the 1# high-pressure discharge tank and the 2# high-pressure discharge tank below;

[0016] 2) When the hydrogen-based vertical furnace is shut down or restarted to resume production, the detection device is turned on, and the position of the diverter valve is controlled according to the voltage change of the receiving coil to guide the qualified DRI to be discharged to the 1# high-pressure discharge tank, and the unqualified DRI to be discharged to the 2# high-pressure discharge tank.

[0017] Furthermore, in the process state 1), the 1# high-pressure discharge tank and the 2# high-pressure discharge tank work alternately.

[0018] The beneficial effect of adopting the above technical solution is that after adopting the device of the present invention, when the hydrogen-based vertical furnace system is shut down and restarted for production due to safety interlock, the unqualified DRI generated passes through the detection device. The detection device is based on electromagnetic detection theory. In the alternating magnetic field generated by the excitation coil, the receiving coil will generate different induced voltages according to the different metallic iron contents of qualified DRI and unqualified DRI. Through the change law of the induced voltage, it is detected whether the DRI reaches the qualified metallization rate, and the diverter valve is controlled to separate the qualified DRI from the unqualified DRI, which is used to guide the production of the hydrogen-based vertical furnace, with rapid detection and guaranteed DRI product quality.

[0019] The method of the present invention can quickly detect whether the direct reduced iron reaches a qualified metallization rate through a detection device, separate qualified DRI from unqualified DRI, and is used to guide hydrogen-based vertical furnace production, ensure DRI product quality, and improve production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0021] Figure 1 It is a schematic diagram of the structure of the device of the present invention;

[0022] Figure 2 It is a schematic diagram of the structure of the detection device of the present invention;

[0023] Figure 3 It is a structural schematic diagram of the control circuit of the detection device of the present invention.

[0024] In the figure: DRI cooler 1, detection device 2, discharge port 3, rotary discharge valve 4, diverter valve 5, 1# high-pressure discharge tank 6, 2# high-pressure discharge tank 7, belt conveyor 8, excitation coil 9, receiving coil 10, voltage sensor 11, controller 12. DETAILED DESCRIPTION

[0025] Figure 1 As shown, the device for detecting the metallization rate of hydrogen-based vertical furnace direct reduced iron includes a DRI cooler 1, a detection device 2, a discharge port 3, a rotary discharge valve 4, a diverter valve 5, a 1# high-pressure discharge tank 6, a 2# high-pressure discharge tank 7 and a belt conveyor 8. The DRI cooler 1 is a cooling device for direct reduced iron. The cooling gas N2 is introduced to cool the hot direct reduced iron to below 80°C, and the direct reduced iron leaves the DRI cooler 1 from the discharge port 3. The cooling medium used by the DRI cooler 1 is nitrogen, which will not react chemically with DRI, but only exchange heat. The nitrogen can be recycled and the loss is low.

[0026] Figure 1As shown, in the device for detecting the metallization rate of direct reduced iron in a hydrogen-based vertical furnace, the rotary discharge valve 4 is located below the DRI cooler 1, and the discharge port 3 of the DRI cooler 1 is connected to the rotary discharge valve 4 through a pipeline. The diverter valve 5 is located below the rotary discharge valve 4, and the rotary discharge valve 4 is connected to the inlet of the diverter valve 5 through a pipeline. The 1# high-pressure discharge tank 6 and the 2# high-pressure discharge tank 7 are located below the rotary discharge valve 4, and the two outlets of the diverter valve 5 are connected to the 1# high-pressure discharge tank 6 and the 2# high-pressure discharge tank 7 through pipelines. The lower outlets of the 1# high-pressure discharge tank 6 and the 2# high-pressure discharge tank 7 are directly opposite to the belt conveyor 8. After adopting the above structure, DRI (direct reduced iron) generated by the hydrogen-based vertical furnace is cooled by the DRI cooler 1, and then flows into the diverter valve 5 through the rotary discharge valve 4 under the action of gravity. The diverter valve 5 discharges the DRI to the 1# high-pressure discharge tank 6 and the 2# high-pressure discharge tank 7 below as needed, and finally discharges it to the belt conveyor 8 for the next process. When the 1# high-pressure discharge tank 6 and the 2# high-pressure discharge tank 7 are in operation, each high-pressure discharge tank is divided into two stages: loading and discharging: in the loading stage, the high-pressure discharge tank is under the pressure of the DRI cooler 1 and receives DRI from the diverter valve 5; in the discharging stage, the high-pressure discharge tank discharges the cold DRI to the belt conveyor 8 under atmospheric pressure.

[0027] Figure 1 , 2 As shown in FIG. 3 , the detection device 2 of the device for detecting the metallization rate of hydrogen-based shaft furnace direct reduced iron comprises an excitation coil 9, a receiving coil 10, a voltage sensor 11 and a controller 12. The excitation coil 9 and the receiving coil 10 are fixedly mounted on the inner wall of the cone of the DRI cooler, above the discharge port 3. Figure 2As shown, the excitation coil 9 and the receiving coil 10 are arranged front and back according to the flow direction of the direct reduced iron, that is, the excitation coil 9 is located at the top and the receiving coil 10 is located at the bottom, so that the DRI will flow through the excitation coil 9 first and then through the receiving coil 10. The excitation coil 9 is connected to the alternating current, and the receiving coil 10 is connected to the voltage sensor 11. The voltage sensor 11 is connected to the P1.0 interface of the controller 12 by circuit or signal, and the P2.0 interface of the controller 12 is connected to the diverter valve 5 by circuit or signal, and the diverter valve 5 adopts an electrically controlled diverter valve 5. After adopting such a structure, when direct reduced iron passes through, the excitation coil 9 generates an alternating magnetic field due to the passage of alternating current. Due to the different metallic iron contents in qualified DRI and unqualified DRI, qualified DRI has a high metallic iron content and generates a strong induced current, while unqualified DRI has a low metallic iron content and generates a weak induced current, so different induced currents will be generated; when the alternating magnetic field passes through the receiving coil 10, the voltage on the receiving coil 10 will change, the voltage sensor 11 detects the voltage change, and sends a signal to the controller 12, the controller 12 quickly determines the metallic iron content in the direct reduced iron according to the signal of the voltage change, and then calculates whether the metallization rate is qualified; then the controller 12 controls the diverter valve 5 to connect to the 1# high-pressure discharge tank 6 or the 2# high-pressure discharge tank 7 according to whether the metallization rate is qualified.

[0028] The qualified DRI and the unqualified DRI are the same pellets, and the total iron content is the same. The metallic iron content corresponds to a unique metallization rate, and whether the metallization rate is qualified can be calculated by the metallic iron content and the total iron content. The metallization rate of the qualified DRI is ≥88%, and the metallization rate of the actual industrial production DRI can be stabilized at about 94%, and the metallization rate of the unqualified DRI is <88%.

[0029] There are two situations in which the unqualified DRI is produced. First, when the safety interlock shutdown occurs, the temperature in the hydrogen-based vertical furnace decreases, the oxidized pellets are not fully reduced, the metallization rate decreases, and unqualified DRI is produced; in this case, the lower part of the hydrogen-based vertical furnace reactor is qualified DRI, and the upper part is the newly produced unqualified DRI. Second, when the hydrogen-based vertical furnace is started to resume production, the temperature inside the hydrogen-based vertical furnace needs to be raised from room temperature to the designed reduction temperature. Because it is in the heating stage, the temperature required for the full reduction of the oxidized pellets is not reached, the metallization rate does not meet the standard, and unqualified DRI is produced; in this case, the lower part of the hydrogen-based vertical furnace reactor is unqualified DRI, and as the temperature rises, qualified DRI begins to appear in the upper part.

[0030] The detection device 2 of the device for detecting the metallization rate of direct reduced iron in a hydrogen-based vertical furnace is in a closed state when the hydrogen-based vertical furnace is in safe, continuous and stable production. When the hydrogen-based vertical furnace system is shut down by safety interlock or restarted to resume production, the detection device 2 is turned on to detect whether the metallization rate of DRI is qualified. The diverter valve 5 is divided into two working states. In the first state, when the hydrogen-based vertical furnace is in stable production, the qualified DRI is guided to be discharged to the 1# high-pressure discharge tank 6 and the 2# high-pressure discharge tank 7 below respectively, without distinction; in this state, the 1# high-pressure discharge tank 6 and the 2# high-pressure discharge tank 7 work alternately. In the second state, when the hydrogen-based vertical furnace system is shut down by safety interlock or restarted to resume production, the position of the diverter valve 5 is controlled by receiving the command of the detection device 2, and the qualified DRI is guided to be discharged to the 1# high-pressure discharge tank 6, and the unqualified DRI is discharged to the 2# high-pressure discharge tank 7.

[0031] Figure 1 , 2 As shown in Figure 3, the method for detecting the metallization rate of hydrogen-based shaft furnace direct reduction iron adopts the following steps:

[0032] 1) During industrial production, the hydrogen-based vertical furnace is in safe, smooth and continuous production most of the time, and the products are all qualified DRI. In this case, the detection device 2 is in a closed state. The DRI (direct reduced iron) generated by the hydrogen-based vertical furnace enters the DRI cooler 1, and the cooling gas N2 is introduced to cool the hot direct reduced iron to below 80°C; after continuous discharge of the rotary discharge valve 4, the DRI flows into the diverter valve 5, and the 1# high-pressure discharge tank 6 and the 2# high-pressure discharge tank 7 work alternately. Under the action of gravity, the diverter valve 5 discharges the DRI alternately into the 1# high-pressure discharge tank 6 and the 2# high-pressure discharge tank 7; then, under the action of atmospheric pressure and gravity, the 1# high-pressure discharge tank 6 and the 2# high-pressure discharge tank 7 alternately discharge the DRI to the belt conveyor 8.

[0033] 2) When a safety interlock shutdown or restart occurs, the metallization rate does not meet the standard because the temperature required for the full reduction of the oxidized pellets is not reached, resulting in unqualified DRI. At this time, qualified DRI and unqualified DRI are in the same vertical furnace reactor. If a safety interlock shutdown occurs, in this case, the lower part of the hydrogen-based vertical furnace reactor is qualified DRI, and the upper part is the unqualified DRI that has just been produced; if the machine is restarted to resume production, in this case, the lower part of the hydrogen-based vertical furnace reactor is unqualified DRI, and as the temperature rises, qualified DRI begins to appear in the upper part. In both cases, the reactor will eventually leave the hydrogen-based vertical furnace reactor through discharge.

[0034] When a safety interlock shutdown or restart to resume production occurs, the detection device 2 is turned on, and the direct reduced iron enters the DRI cooler 1 under the action of gravity. The cooling gas N2 is introduced to cool the hot direct reduced iron to below 80°C. With the continuous discharge of the lower rotary discharge valve 4, qualified DRI and unqualified DRI move to the detection device 2 at the cone of the DRI cooler 1.

[0035] The detection device 2 is based on electromagnetic detection theory. The excitation coil 9 is supplied with alternating current to generate an alternating magnetic field. Due to the different metallic iron contents in qualified DRI and unqualified DRI, induced currents of different strengths are generated. When the alternating magnetic field passes through the receiving coil 10, the voltage on the receiving coil 10 changes due to the different strengths of the induced current passing through the DRI. The voltage sensor 11 detects the voltage change and sends a signal to the controller 12. The controller 12 quickly determines the metallic iron content in the direct reduced iron based on the voltage change signal, and then calculates whether the metallization rate is qualified.

[0036] Qualified DRI and unqualified DRI leave the DRI cooler 1 through the discharge port 3 and come to the rotary discharge valve 4. The rotary discharge valve 4 continuously rotates to discharge, controls the discharge rate of the DRI cooler 1, ensures that the cold DRI is continuously discharged, and comes to the diverter valve 5.

[0037] If the controller 12 detects that the DRI is qualified, the detection device 2 issues an instruction to control the position of the diverter valve 5 to guide the qualified DRI to be discharged to the 1# high-pressure discharge tank 6; if the DRI is detected to be unqualified, the detection device 2 issues an instruction to control the diverter valve 5 to turn to the opposite position to guide the unqualified DRI to be discharged to the 2# high-pressure discharge tank 7; thereby separating the qualified DRI from the unqualified DRI.

[0038] The 1# high pressure discharge tank 6 and the 2# high pressure discharge tank 7 discharge materials respectively, and the qualified DRI and the unqualified DRI are transported to different silos for storage by the belt conveyor 8. The qualified DRI is used for steel production and is a high-quality steelmaking raw material, while the unqualified DRI needs to be re-loaded into the hydrogen-based vertical furnace for smelting to obtain a qualified metallization rate.

[0039] In conventional processes, the predictive discharge method used on site is too dependent on the operator's experience. The hydrogen-based vertical furnace direct ironmaking process is a new low-carbon ironmaking process in China. The internal operation of the vertical furnace still needs to be explored and accumulated in production. Human judgment has errors and poor stability, and the quality of DRI cannot be guaranteed. Although the chemical analysis method can accurately detect the metallic iron content and metallization rate, it takes several hours to produce results and is mainly used for multiple chemical composition analyses of DRI. This detection device and method can quickly detect whether DRI has reached a qualified metallization rate, avoid the influence of human factors, operate stably, ensure the quality of DRI, and provide stable, qualified and high-quality raw materials for subsequent steelmaking.

[0040] The device and method have the following advantages:

[0041] (1) The detection device can quickly detect whether the direct reduced iron has reached the qualified metallization rate, separate qualified products from unqualified products, and be used to guide hydrogen-based vertical furnace production, ensure DRI quality, and improve production efficiency;

[0042] (2) It can avoid over-reliance on the experience of on-site operators, reduce human judgment errors, and improve stability;

[0043] (3) The detection device is installed on the inner wall of the cone of the DRI cooler, which occupies a small space and has little impact on the normal discharge of the DRI cooler;

[0044] (4) It can accurately calculate the time required from the start-up of the hydrogen-based vertical furnace to the DRI metallization rate reaching the standard, and the time from the system shutdown to the unqualified DRI passing through the cooler cone, so as to facilitate the understanding of the operation status of the hydrogen-based vertical furnace, formulate plans, and arrange production.

Claims

1. A device for detecting the metallization rate of hydrogen-based shaft furnace direct reduction iron, characterized in that: The invention comprises a DRI cooler (1), a detection device (2), a diverter valve (5), a 1# high-pressure discharge tank (6) and a 2# high-pressure discharge tank (7); the DRI cooler (1) is connected to an inlet of the diverter valve (5) through a pipeline, and two outlets of the diverter valve (5) are respectively connected to the 1# high-pressure discharge tank (6) and the 2# high-pressure discharge tank (7); the detection device (2) comprises an excitation coil (9) and a receiving coil (10); the excitation coil (9) and the receiving coil (10) are arranged inside the DRI cooler (1); the excitation coil (9) and the receiving coil (10) are arranged front and back according to the flow direction of the direct reduced iron. The excitation coil (9) is connected to an alternating current, and the receiving coil (10) is connected to a voltage sensor (11); the excitation coil (9) is supplied with alternating current to generate an alternating magnetic field, and due to the difference in the metallic iron content in the qualified DRI and the unqualified DRI, induced currents of different strengths are generated. When the alternating magnetic field passes through the receiving coil (10), the voltage on the receiving coil (10) changes due to the different strengths of the induced current passing through the DRI; the detection device (2) controls the diverter valve (5) according to the voltage change of the receiving coil (10) to guide the qualified DRI and the unqualified DRI to be discharged into different high-pressure discharge tanks; The detection device (2) further comprises a voltage sensor and a controller; the voltage sensor is signal-connected to the controller; the controller controls the diverter valve (5) to connect to the 1# high-pressure discharge tank (6) or the 2# high-pressure discharge tank (7).

2. The device for detecting the metallization rate of hydrogen-based shaft furnace direct reduction iron according to claim 1, characterized in that: The excitation coil (9) and the receiving coil (10) are fixedly mounted on the inner wall of the cone portion at the upper portion of the discharge port (3) of the DRI cooler (1).

3. A method for detecting the metallization rate of hydrogen-based shaft furnace direct reduction iron, using the device according to claim 1 or 2, characterized in that: The following process conditions are adopted: 1) when the hydrogen-based vertical furnace is in stable production, the detection device (2) is in a closed state, and the diverter valve (5) guides the qualified DRI to be discharged to the 1# high-pressure discharge tank (6) and the 2# high-pressure discharge tank (7) below; 2) When the hydrogen-based vertical furnace is shut down or restarted to resume production, the detection device (2) is turned on, and alternating current is passed through the excitation coil (9) to generate an alternating magnetic field. Due to the difference in the metallic iron content in the qualified DRI and the unqualified DRI, induced currents of different strengths are generated. When the alternating magnetic field passes through the receiving coil (10), the voltage on the receiving coil (10) changes due to the different strengths of the induced current passing through the DRI. According to the change in the voltage of the receiving coil (10), the position of the diverter valve (5) is controlled to guide the qualified DRI to be discharged into the 1# high-pressure discharge tank (6), and the unqualified DRI to be discharged into the 2# high-pressure discharge tank (7).

4. A method for detecting the metallization rate of hydrogen-based shaft furnace direct reduction iron according to claim 3, characterized in that: In the process state 1), the 1# high-pressure discharge tank (6) and the 2# high-pressure discharge tank (7) work alternately.

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