Device and method for testing conductivity of solid direct reduced iron during loading

Abstract

The invention discloses a device and a method for testing the conductivity of solid direct reduced iron during loading, and relates to the technical field of the conductivity of reduced iron. The device comprises a wire assembly, a cylinder and a pressure applying control assembly, the wire assembly is arranged on the inner side of the cylinder, the pressure applying control assembly comprises a load applying device and a computer, the load applying device is electrically connected with the computer, the computer is used for taking the load of the load applying device as a target value, and a conductor sheet is arranged on the inner side of the cylinder. The invention designs a device which not only can determine the length and the sectional area of a plurality of DRIs when the DRIs are stacked, but also can apply a target load to the DRIs so as to test the conductivity of the stacked DRIs under the load condition, and through the combination of the device and the method, the conductivity of the stacked DRIs under the load condition when the temperature is constant and variable is tested.

Description

Technical Field

[0001] The invention relates to the technical field of reduced iron conductivity, in particular to a device and method for testing the conductivity of solid-state direct reduced iron under load. Background Art

[0002] The hydrogen-based direct reduction shaft furnace process does not require coking, sintering, ironmaking and other links, and can control carbon emissions from the source. Compared with blast furnace hydrogen-rich reduction, the carbon reduction rate can reach more than 50%, and the emission reduction potential is relatively large.

[0003] Direct reduced iron (DRI) is a high-quality charge for smelting high-quality steel. It can be added as a "diluent" to electric furnace smelting with scrap steel as the main raw material. The raw materials for the global mainstream electric furnace steelmaking process are: scrap steel (50%-70%) + DRI (30% + 50%). At the same time, the vanadium-titanium direct reduced iron electric furnace smelting has the ability to provide chemical energy and heat for green hydrogen-green electricity through full-process transformation, and is the most suitable "carbon-neutral" vanadium-titanium ore smelting process. Electric furnace smelting is a process of using electric energy to heat electrodes and charge to high temperatures, thereby melting, decomposing, and reducing the charge to achieve metal smelting. In the electric furnace, electric energy is input into the furnace through electrodes, and an arc is generated between the electrodes and the charge. The high temperature of the arc is used to heat and melt the charge.

[0004] Conductivity is a physical quantity that measures the electrical conductivity of a material. For an electric furnace, the conductivity of the charge directly affects the efficiency of converting electrical energy into thermal energy and the uniformity of the temperature in the furnace. If the conductivity of the charge is inconsistent, it may lead to uneven temperature distribution in the furnace, thus affecting the quality and production efficiency of the product. In addition, charge with low conductivity helps to reduce power loss, improve energy efficiency, and reduce production costs. However, during the smelting process of an electric furnace, the height of the material layer varies greatly due to factors such as the electric furnace distribution system and the smelting process. Taking the solid DRI at the bottom of the material layer as an example, the height of the material layer is different, and the load borne by the lower DRI is also different, resulting in different contact areas between the DRIs, which ultimately affects the conductivity of this part of the DRI. Therefore, testing the conductivity of the stacked solid DRI under load is crucial for electric furnace smelting.

[0005] Conductivity is a parameter used to describe the ease of charge flow in a substance. The calculation formula is σ=GL / A=IL / (AU), where σ represents conductivity; G represents conductance; L represents conductor length; A represents conductor cross-sectional area; I represents current; and U represents voltage. The most commonly used test methods for solid conductivity include direct measurement and four-wire method (four-terminal method). Among them, the direct measurement method is to make the material to be tested into electrodes of a certain shape and size, and calculate the conductivity by measuring the resistance value between the electrodes. During the test, the material to be tested needs to be processed into electrodes of a certain shape and size, usually in the form of round or rectangular sheets. The shape of DRI is approximately spherical, with an irregular shape and large surface roughness, and the direct measurement method cannot be used. The four-wire method is mainly used to accurately measure low-value resistors. The principle is that a constant current power supply supplies current to the low-value resistor to be measured, and the voltage is measured through two voltage leads to form the potential difference on the low-value resistor to be measured by the current supplied by the constant current power supply, and then the conductivity is calculated by the resistance value;

[0006] Testing the conductivity of solid DRI using the four-wire method requires designing a device that can not only determine the length and cross-sectional area of ​​multiple DRI stacks, but also apply a target load to the DRI.

[0007] Existing four-wire method test devices usually use a fixture to fix the sample, but for stacked DRI samples, the fixture cannot be used directly. It is necessary to design a device that can not only determine the length and cross-sectional area of ​​multiple DRI stacks, but also apply a target load to the DRI.

[0008] Therefore, a new solution to the above problems needs to be proposed. Summary of the invention

[0009] The object of the present invention is to provide a device and method for testing the electrical conductivity of solid-state direct-reduced iron under load, so as to solve the technical problems raised in the background technology.

[0010] To achieve the above-mentioned purpose, the present invention provides the following technical solution: a device for testing the electrical conductivity of solid direct reduced iron under load, comprising a wire assembly, a cylinder and a pressure control assembly, wherein the wire assembly is arranged on the inner side of the cylinder, the pressure control assembly comprises a load applying device and a computer, the load applying device is electrically connected to the computer, the computer is used to take the load of the load applying device as a target value, and a conductor sheet is arranged on the inner side of the cylinder.

[0011] Furthermore, the wire assembly includes a first wire, a second wire, a third wire and a fourth wire, and the first wire, the second wire, the third wire and the fourth wire are sequentially arranged on the inner side of the cylinder.

[0012] Furthermore, the cylinder is an open cylinder at the top, and the material of the cylinder is a high temperature resistant insulator.

[0013] Furthermore, the conductor sheets are inlaid on the side wall of the cylinder, and the conductor sheets are made of high temperature resistant material.

[0014] Furthermore, the output ends of the first wire and the fourth wire are connected to an ammeter, and the output ends of the second wire and the third wire are connected to a voltmeter.

[0015] Furthermore, bottom ends of the first wire, the second wire, the third wire and the fourth wire are all connected to the conductor sheet.

[0016] A method for testing the electrical conductivity of solid-state direct reduced iron under load, comprising at least the following steps:

[0017] S1: Load solid direct reduced iron into a cylinder with a known diameter, and calculate the cross-sectional area of ​​the cylinder based on the diameter, recorded as A;

[0018] S2: The distance between the conductor sheets at the upper and lower ends is recorded as L;

[0019] S3: Connect the first wire and the fourth wire to the ammeter, connect the second wire and the third wire to the voltmeter, and after the constant current power supply supplies current to the device, record the values ​​of the ammeter and the voltmeter, which are recorded as I and U respectively;

[0020] S4: Calculate the electrical conductivity of solid direct reduced iron in a piled state under load conditions according to the formula σ=GL / A=IL / (AU).

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The present invention designs a device that can not only determine the length and cross-sectional area of ​​multiple DRI stacks, but also apply a target load to the DRI to test the conductivity of the stacked DRI under the load condition.

[0023] 2. The present invention combines a device and a method to test the conductivity of DRI deposited under load conditions at isothermal and variable temperatures;

[0024] 3. When the device of the present invention is used to test the conductivity of solid-state DRI under load, the diameter of the cylindrical device can be adjusted (i.e., the cross-sectional area can be adjusted), and the height of the device and the spacing between the conductor sheets at the upper and lower ends can also be adjusted, which can meet the needs of loading DRI of different particle sizes and numbers. The load is adjustable, and the conductivity of DRI at different material layer heights can be simulated and tested.

[0025] 4. The present invention places the device in a heating furnace, introduces inert gas, heats up to the target temperature, tests the conductivity of direct reduced iron under load at different temperatures and in a stacked state, and can also change the heating or cooling rate, set the temperature system, and record the changes in current and voltage in real time to obtain the change curve of DRI under load under different heating system conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0027] Figure 1 It is a schematic diagram of a conductivity testing device for solid direct reduced iron under load according to the present invention;

[0028] Figure 2 It is a schematic diagram of the load applying and controlling device of the present invention;

[0029] Figure 3 It is a front view and a top view of the load applying device of the present invention;

[0030] Figure 4 This is a schematic diagram of the principle of testing the electrical conductivity of solid direct reduced iron under load in the present invention;

[0031] Figure 5 It is a cross-sectional view of the electrical conductivity testing device of solid direct reduced iron of the present invention;

[0032] Figure 6 It is a schematic diagram of the conductivity of the solid direct reduced iron in a stacked state when loaded and unloaded according to the present invention;

[0033] Figure 7 It is a schematic diagram of the electrical conductivity of solid direct reduced iron in a stacked state with and without loading under isothermal conditions of the present invention.

[0034] In the figure: 1. first wire; 2. second wire; 3. third wire; 4. fourth wire; 5. cylinder; 6. conductor sheet; 7. load applying device; 8. computer. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0036] Embodiment 1:

[0037] See also Figure 1 - Figure 5 A device for testing the electrical conductivity of solid direct reduced iron under load includes a wire assembly, a cylinder 5 and a pressure control assembly. The wire assembly is arranged on the inner side of the cylinder 5. The pressure control assembly includes a load applying device 7 and a computer 8. The load applying device 7 is electrically connected to the computer 8. The computer 8 is used to take the load of the load applying device 7 as a target value. A conductor sheet 6 is arranged on the inner side of the cylinder 5.

[0038] The wire assembly comprises a first wire 1 , a second wire 2 , a third wire 3 and a fourth wire 4 , and the first wire 1 , the second wire 2 , the third wire 3 and the fourth wire 4 are arranged in sequence on the inner side of the cylinder 5 .

[0039] The cylinder 5 is an open-top cylinder, and the material of the cylinder 5 is a high-temperature resistant insulator.

[0040] A total of four conductive sheets 6 are embedded on the side wall of the cylinder 5 , and the conductive sheets 6 are made of high temperature resistant material.

[0041] The output ends of the first wire 1 and the fourth wire 4 are connected to an ammeter, and the output ends of the second wire 2 and the third wire 3 are connected to a voltmeter.

[0042] The bottom ends of the first wire 1 , the second wire 2 , the third wire 3 and the fourth wire 4 are all connected to the conductor sheet 6 .

[0043] Embodiment 2:

[0044] See also Figure 1 - Figure 5 , this embodiment proposes a method for testing the electrical conductivity of solid direct reduced iron under load based on the above embodiment 1;

[0045] A method for testing the electrical conductivity of solid-state direct reduced iron under load, comprising at least the following steps:

[0046] S1: Solid direct reduced iron is loaded into a cylinder (5) with a known diameter, and the cross-sectional area of ​​the cylinder is calculated according to the diameter, which is recorded as A;

[0047] S2: Figure 1 (b) and Figure 1 In (d), the distance between the conductor sheets 6 at the upper and lower ends is denoted as L;

[0048] S3: Connect the first wire 1 and the fourth wire 4 to the ammeter, connect the second wire 2 and the third wire 3 to the voltmeter, and after the constant current power supply supplies current to the device, record the values ​​of the ammeter and the voltmeter, which are recorded as I and U respectively;

[0049] S4: Calculate the electrical conductivity of solid direct reduced iron in a piled state under load conditions according to the formula σ=GL / A=IL / (AU).

[0050] Based on the above two embodiments, the following experimental cases are further proposed:

[0051] First experimental case:

[0052] Using a device with a cylinder inner diameter of 45 mm, the conductivity of solid direct reduced iron (about 12.5 mm in diameter) in a stacked state was tested at room temperature with and without load. The current and voltage values ​​were recorded by a computer, and the corresponding conductivity values ​​were obtained. In this experiment, the shortest time interval for recording the current and voltage values ​​was 0.01 s.

[0053] The applicant first tested the conductivity of solid direct reduced iron in a stacked state when no load was applied. The results are shown in Figure 6 Unloaded stage. When unloaded, the conductivity test value of solid direct reduced iron in a piled state is very stable, with a conductivity of about 120S / m. Then, the applicant tested the conductivity of solid direct reduced iron in a piled state when loaded. By connecting a computer to a load applying device, the load was set to about 17N, and the conductivity test results are shown in FIG. Figure 6 Loading stage. When loaded, the conductivity of direct reduced iron increases, and the conductivity value is about 460S / m. This is because the DRI filling process is not in close contact with the surroundings. After loading, the DRI is in close contact with each other, and the pores are reduced, the conductivity is enhanced, the resistance is reduced, and the conductivity increases.

[0054] Depend on Figure 6 It can be seen that there is a significant difference in the conductivity of solid direct reduced iron in the stacked state when loaded and unloaded. The experimental results prove that the influence of the material layer height on the conductivity of solid direct reduced iron through load simulation is very important for electric furnace smelting.

[0055] Under isothermal conditions, the conductivity of solid direct reduced iron under load in a stacked state is tested. The specific steps are as follows:

[0056] (1) Solid direct reduced iron is loaded into a cylinder with a known diameter. See the cross-sectional view. Figure 5 . Calculate the cross-sectional area of ​​the cylinder based on the diameter and record it as A.

[0057] (2) Figure 1 (b) and Figure 1 In (d), the distance between the conductor plates at the upper and lower ends is denoted by L.

[0058] (3) Place the cylinder in a heating furnace and introduce inert gas to prevent oxidation of the direct reduced iron during the heating process. Heat to the target temperature and keep it warm for a period of time until the temperature does not change.

[0059] (4) The applied load is set as the target value by a computer.

[0060] (5) Wires 1 and 4 are connected to an ammeter, and wires 2 and 3 are connected to a voltmeter. After a constant current power supply supplies current to the device, the values ​​of the ammeter and voltmeter are recorded and recorded as I and U, respectively.

[0061] (6) The electrical conductivity of solid direct reduced iron in a stacked state under load under isothermal conditions is calculated according to the formula σ = GL / A = IL / (AU).

[0062] Second experimental case:

[0063] Using a device with a cylinder inner diameter of 45 mm, the conductivity of solid direct reduced iron (about 12.5 mm in diameter) in a stacked state was tested under isothermal conditions without load and with load. The current and voltage values ​​were recorded by a computer, and the corresponding conductivity values ​​were obtained. The results are shown in Figure 7 .from Figure 7 It can be seen that when the test temperatures are 200°C, 300°C, and 400°C, respectively, and the load is about 17N, the conductivity test values ​​of solid direct reduced iron in a stacked state under isothermal conditions are all higher than those when there is no load.

[0064] Through load, simulation and testing of the effect of material layer height on the conductivity of solid direct reduced iron is crucial for electric furnace smelting.

[0065] Under variable temperature conditions, the conductivity of solid direct reduced iron under load in a stacked state is tested. The specific steps are as follows:

[0066] (1) Solid direct reduced iron is loaded into a cylinder with a known diameter. See the cross-sectional view. Figure 5 . Calculate the cross-sectional area of ​​the cylinder based on the diameter and record it as A.

[0067] (2) Figure 1 (b) and Figure 1 In (d), the distance between the conductor plates at the upper and lower ends is denoted by L.

[0068] (3) Place the cylinder in a heating furnace and introduce inert gas to prevent oxidation of the direct reduced iron during the heating process. Set the temperature regime by changing the heating or cooling rate.

[0069] (4) The applied load is set as the target value by a computer.

[0070] (5) Wires 1 and 4 are connected to an ammeter, and wires 2 and 3 are connected to a voltmeter. After a constant current power supply supplies current to the device, the values ​​of the ammeter and voltmeter are recorded and recorded as I and U, respectively.

[0071] (6) The electrical conductivity of solid direct reduced iron in a stacked state under variable temperature conditions is calculated according to the formula σ = GL / A = IL / (AU).

[0072] In summary, the present invention achieves the following technical effects:

[0073] 1. Test the conductivity of solid-state DRI under load.

[0074] The diameter of the cylindrical device can be adjusted (i.e. the cross-sectional area can be adjusted), and the height of the device and the spacing between the upper and lower conductor sheets can also be adjusted to meet the needs of loading DRI of different particle sizes and numbers. The load can be adjusted to simulate the test of the conductivity of DRI at different material layer heights.

[0075] 2. Test the conductivity of DRI under load under isothermal and variable temperature conditions.

[0076] Place the device in a heating furnace, introduce inert gas, heat it to the target temperature, and test the conductivity of direct reduced iron under load at different temperatures, in a stacked state, and under load. You can also change the heating or cooling rate, set the temperature system, and record the changes in current and voltage in real time to obtain the change curve of DRI under load under different heating system conditions.

[0077] The experimental results once again prove that the conductivity of solid direct reduced iron at different material layer heights is crucial for electric furnace smelting through load simulation testing. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes that fall within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

Claims

1. A device for testing the electrical conductivity of solid direct reduced iron under load, characterized in that: The invention comprises a wire assembly, a cylinder (5) and a pressure control assembly, wherein the wire assembly is arranged on the inner side of the cylinder (5), the pressure control assembly comprises a load applying device (7) and a computer (8), the load applying device (7) is electrically connected to the computer (8), the computer (8) is used to take the load of the load applying device (7) as a target value, and a conductor sheet (6) is arranged on the inner side of the cylinder (5).

2. A device for testing the electrical conductivity of solid direct reduced iron under load according to claim 1, characterized in that: The wire assembly comprises a first wire (1), a second wire (2), a third wire (3) and a fourth wire (4); the first wire (1), the second wire (2), the third wire (3) and the fourth wire (4) are arranged in sequence on the inner side of the cylinder (5).

3. The device for testing the electrical conductivity of solid direct reduced iron under load according to claim 1, characterized in that: The cylinder (5) is a cylinder with an opening at the top, and the material of the cylinder (5) is a high-temperature resistant insulator.

4. The device for testing the electrical conductivity of solid direct reduced iron under load according to claim 1, characterized in that: A total of four conductive sheets (6) are embedded on the side wall of the cylinder (5), and the conductive sheets (6) are made of high temperature resistant material.

5. The device for testing the electrical conductivity of solid direct reduced iron under load according to claim 2, characterized in that: The output ends of the first wire (1) and the fourth wire (4) are connected to an ammeter, and the output ends of the second wire (2) and the third wire (3) are connected to a voltmeter.

6. The device for testing the electrical conductivity of solid direct reduced iron under load according to claim 2, characterized in that: The bottom ends of the first wire (1), the second wire (2), the third wire (3) and the fourth wire (4) are all connected to the conductor sheet (6).

7. A method for testing the electrical conductivity of solid direct-reduced iron under load, used in the device for testing the electrical conductivity of solid direct-reduced iron under load as claimed in any one of claims 1 to 6, characterized in that: At least the following steps are included: S1: Solid direct reduced iron is loaded into a cylinder (5) with a known diameter, and the cross-sectional area of ​​the cylinder is calculated according to the diameter, which is recorded as A; S2: The distance between the conductor sheets (6) at the upper and lower ends is recorded as L; S3: Connect the first wire (1) and the fourth wire (4) to an ammeter, connect the second wire (2) and the third wire (3) to a voltmeter, and after a constant current power supply supplies current to the device, record the values ​​of the ammeter and the voltmeter, which are recorded as I and U respectively; S4: Calculate the conductivity of solid direct reduced iron in a piled state under load conditions according to the formula σ=GL / A=IL / (AU).

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