Thermal state test system for desulfurization of bottom blowing lime powder

Abstract

The invention discloses a thermal state test system for bottom blowing lime powder desulfurization. The thermal state test system comprises a powder spraying tank body, a gas supply unit, a feeding unit and a spraying unit, the gas supply unit is respectively communicated with the powder spraying tank body and the spraying unit; the powder spraying tank body is communicated with the feeding unit; and the feeding unit is communicated and converged with the spraying unit and then is communicated with a discharging pipe. According to the bottom blowing desulfurization powder experimental device for molten iron in the induction furnace under the laboratory condition, through the powder spraying tank, the pipeline, the bottom blowing gas supply element and some necessary control instruments, the desulfurization powder is sprayed into the molten iron through carrier gas to desulfurize the molten iron; theoretical and experimental data are provided for formulation of a ladle bottom blowing molten iron desulfurization process in large-scale production.

Description

Technical Field

[0001] The present invention relates to the technology of bottom-blowing powder desulfurization experiment on hot metal in an induction furnace or a ladle. More specifically, it relates to a hot-state test system for bottom-blowing lime powder desulfurization. Background Art

[0002] Hot metal pretreatment is an important technical means commonly used by iron and steel enterprises to improve product quality and develop high-value-added products. Currently, the following two methods of hot metal desulfurization outside the furnace are widely used at home and abroad: the injection method and the KR mechanical stirring method. The KR mechanical stirring method is widely adopted because of its easy operation, low unit consumption of desulfurizer, stable desulfurization effect and good stirring kinetic conditions. Although the KR method has obvious advantages in deep desulfurization and ultra-deep desulfurization, due to the mixing characteristics of the KR method stirring, most of the lime will agglomerate after entering the hot metal under the action of mechanical stirring, and the desulfurization reaction only occurs on the outer surface of the desulfurizer, and the dispersion effect of the desulfurizer is not ideal, the lime utilization rate is low, resulting in an increase in lime consumption, and causing problems such as large temperature drop of hot metal and high iron loss.

[0003] There are many studies on the problem of insufficient production capacity caused by the short service life of the hot metal pretreatment lance and the KR stirrer. The research mainly focuses on discussing and improving the structural parameters of the lance and the stirrer, and improving the service life of the lance and the KR stirrer in actual application, thus achieving the effects of improving production capacity and reducing production costs. The proposed self-pulsating stirrer for hot metal desulfurization can provide a function of suppressing the tangential flow of stirring, strengthening the axial flow and radial flow of stirring, playing a role in suppressing the tangential flow of stirring, strengthening the axial and radial flow of stirring, achieving the effects of reducing the forced vortex area, expanding the free vortex area and improving the stirring and mixing characteristics, and can effectively improve the hot metal KR stirring desulfurization kinetic conditions and desulfurization technical and economic indicators. However, inevitably, some of the desulfurizer will overflow into the air during the feeding process, which to a certain extent results in a low lime utilization rate and an increase in lime consumption. Therefore, it is necessary to further optimize the feeding method of the desulfurizer.

[0004] In the existing patent applications, for example, Chinese Patent Publication No. CN104480251B discloses a pretreatment device and application and smelting method for simultaneous desulfurization, de-siliconization and de-phosphorization of hot metal. The pretreatment device includes a powder injection tank, a powder conveying pipeline, a pre-processor. The powder injection tank is provided with a fluidization device and a powder distributor. The powder injection lance is installed on the side wall of the pre-processor, provided with a slag discharging device, and an iron tapping port is provided at the bottom. This method can inject magnesium particles, lime powder, fluorite powder, etc. The top lance injection is used to complete the three-deoxidation task, and the bottom-blowing porous plug blows gas for enhanced stirring. However, this invention mainly uses the top lance for powder injection desulfurization, and can de-phosphorize and de-siliconize at the same time. The bottom-blowing element is mainly used for gas stirring and cannot inject powder.

[0005] As disclosed in Chinese Patent Publication No. CN111254257B, a mechanical stirring desulfurization method for hot metal based on bottom blowing powder is provided. By arranging a porous plug at a specific position at the bottom of the hot metal ladle, the desulfurizing agent is blown into the hot metal ladle, improving the thermodynamic conditions of the desulfurization reaction, increasing the floating stroke of the desulfurizing agent, and expanding the mixing and dispersion area of the molten bath stirring. The main difference from the present invention is the different structural form of the tank body. The present invention adopts a quantitative step feeding method, and the feeding amount is determined by the rotation speed of the speed regulating motor. Theoretically, it can be accurately controlled to 25 g / min to 250 g / min, with small experimental data error and high accuracy. The structural form of the powder injection element is different. The present invention adopts a suspended powder injection element. The structure of this powder injection element is to add a fluidized bed at the bottom of the original powder injection element. When the powder is sprayed into the bottom of the powder injection element, due to its special designed suspension structure, the incoming powder is fully suspended, and then the powder is sprayed into the hot metal in the furnace with the carrier gas, without causing powder accumulation and blocking the gas supply element.

[0006] The above-mentioned patented technology adopts a conventional negative pressure injector structure. The problem with this structure is that if the carrier gas volume is small and the gas flow rate is relatively slow, the negative pressure generated at the end of the conveyor is small, which is likely to cause powder accumulation, resulting in pipeline blockage and preventing the test from proceeding normally. Summary of the Invention

[0007] Aiming at the defects existing in the prior art, the purpose of the present invention is to provide a hot state test system for bottom blowing lime powder desulfurization, an experimental device for bottom blowing desulfurizing powder into molten hot metal in an induction furnace under laboratory conditions. Through a powder injection tank, pipelines, a bottom blowing gas supply element and some necessary control instruments, the desulfurizing powder is sprayed into the hot metal by using the carrier gas to desulfurize the hot metal, providing theoretical and experimental data for formulating the iron ladle bottom blowing hot metal desulfurization process in industrial production.

[0008] To achieve the above purpose, the present invention adopts the following technical solutions:

[0009] A hot state test system for bottom blowing lime powder desulfurization, comprising a powder injection tank body, a gas supply unit, a feeding unit and a spraying unit;

[0010] The gas supply unit is respectively connected and communicated with the powder injection tank body and the spraying unit;

[0011] The powder injection tank body is connected and communicated with the feeding unit;

[0012] The feeding unit is connected and communicated with the spraying unit and then connected and communicated with the discharge pipe.

[0013] Preferably, the volume of the powder injection tank body is 8 - 20 liters;

[0014] A vibrator is provided at the middle position of the powder spraying tank body.

[0015] Preferably, the air supply unit includes an intake main pipe and a first gas transmission pipeline, a second gas transmission pipeline, and a third gas transmission pipeline that are connected to the intake main pipe;

[0016] The first gas transmission pipeline is connected to the upper position of the powder spraying tank body;

[0017] The second gas transmission pipeline is connected to the vibrator;

[0018] The third gas transmission pipeline is connected to the spraying unit.

[0019] Preferably, a stop valve is provided on the intake main pipe;

[0020] A first electromagnetic cut-off valve, a first pressure regulating valve, a first pressure gauge, and a first check valve are sequentially provided on the first gas transmission pipeline along the gas transmission direction;

[0021] A second pressure regulating valve and a second pressure gauge are sequentially provided on the second gas transmission pipeline along the gas transmission direction;

[0022] A second electromagnetic cut-off valve, a third pressure regulating valve, a third pressure gauge, and a second check valve are sequentially provided on the third gas transmission pipeline along the gas transmission direction.

[0023] Preferably, the feeding unit includes a step feeder;

[0024] The step feeder includes a feeder, a blanking pipe, a feeding cup, and a variable frequency motor;

[0025] The feeder is connected to the powder spraying tank body;

[0026] The upper end of the blanking pipe is connected to the powder outlet of the feeder;

[0027] The feeding cup is arranged in the blanking pipe;

[0028] The variable frequency motor is connected to the feeding cup.

[0029] Preferably, a third electromagnetic cut-off valve is further provided on the blanking pipe.

[0030] Preferably, a sealing ring is further provided between the feeding cup and the inner wall of the blanking pipe.

[0031] Preferably, the spraying unit includes a booster with a double-layer sleeve structure;

[0032] The air inlet of the booster is connected to the third gas transmission pipeline;

[0033] An outer sleeve and a central sleeve disposed within the outer sleeve are connected to the air outlet of the booster;

[0034] The outlet side of the central sleeve is located at the front end of the outlet side of the blanking pipe, and the outlet side of the outer sleeve is located at the rear end of the outlet side of the blanking pipe.

[0035] Preferably, the discharge pipe is connected to the induction furnace through a powder conveying pipeline;

[0036] A suspension bottom-blowing powder injection element is provided at the powder outlet of the powder conveying pipeline.

[0037] Preferably, the suspension bottom-blowing powder injection element includes a powder injection element head and a powder inlet pipe;

[0038] The powder injection element head is connected to the powder outlet of the powder conveying pipeline;

[0039] A suspension air chamber is provided inside the powder injection element head;

[0040] One end of the powder inlet pipe is connected to the suspension air chamber, and the other end faces the molten iron in the induction furnace.

[0041] A hot test system for bottom-blowing lime powder desulfurization provided by the present invention is used to conduct desulfurization experiments on molten iron in an induction furnace by bottom-blowing desulfurization powder, providing a theoretical basis and technical support for the technical development of the desulfurization process in industrial mass production and the formulation of production technology processes. Developing a more reasonable and advanced molten iron pretreatment desulfurization process is of great significance for the production of ultra-low sulfur steel with increasingly demanding modern technology requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 is a schematic diagram of the frame structure of the hot test system of the present invention;

[0043] Figure 2 is a schematic diagram of the frame structure of the feeding unit in the hot test system of the present invention;

[0044] Figure 3 is a schematic diagram of the frame structure of the injection unit in the hot test system of the present invention;

[0045] Figure 4 is a schematic diagram of the structure of the suspension bottom-blowing powder injection element in the hot test system of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0046] In order to better understand the above technical solutions of the present invention, the technical solutions of the present invention will be further described below with reference to the drawings and embodiments.

[0047] Combined with Figure 1As shown in the figure, a hot state test system for bottom blowing lime powder desulfurization provided by the present invention includes a powder spraying tank body 100, a gas supply unit 200, a feeding unit 300 and a spraying unit 400.

[0048] The gas supply unit 200 is respectively connected to the powder spraying tank body 100 and the spraying unit 400.

[0049] The powder spraying tank body 100 is connected to the feeding unit 300.

[0050] The feeding unit 300 is connected and merged with the spraying unit 400, and then connected to the discharge pipe 500.

[0051] The volume of the powder spraying tank body 100 is 8 - 20 liters. Since the powder spraying tank body 100 is the core design of the hot state test system of the present invention, its structure and the control method adopted directly determine the powder spraying effect of the powder spraying device. First, the experimental accuracy should be considered. Since the charged amount of the test hot metal is 100 kg, the gas flow rate is ≤20 NL / min, and the sprayed agent is in grams, the volume of the powder spraying tank body 100 cannot be designed too large, otherwise the experimental error will be large and the experimental requirements cannot be met. However, it cannot be designed too small either. If it is too small, the free space of the powder spraying tank body 100 is insufficient, resulting in difficult discharging. Therefore, the volume of the powder spraying tank body 100 of the hot state test system of the present invention is designed to be 8 - 20 liters.

[0052] A vibrator 1 is arranged at the middle position of the powder spraying tank body 100. Due to the particularity of the powder spraying tank body 100, it cannot be designed into a fluidized bed structure. Therefore, in order to make the feeding smoother, a vibrator 1 for feeding is added to the powder spraying tank body 100.

[0053] The gas supply unit 200 includes an intake main pipe 2 and a first gas transmission pipeline 3, a second gas transmission pipeline 4 and a third gas transmission pipeline 5 connected to the intake main pipe 2.

[0054] The first gas transmission pipeline 3 is connected to the upper part of the powder spraying tank body 100.

[0055] The second gas transmission pipeline 4 is connected to the vibrator 1. The vibrator 1 is driven by compressed air, and its amplitude and vibration frequency are determined by the pressure of the driving gas. The greater the pressure, the greater the amplitude and frequency, and the greater the vibration intensity; conversely, it is smaller.

[0056] The third gas transmission pipeline 5 is connected to the spraying unit 400.

[0057] A stop valve 6 is arranged on the intake main pipe 2.

[0058] On the first gas transmission pipeline 3, a first electromagnetic cut-off valve 7, a first pressure regulating valve 8, a first pressure gauge 9 and a first check valve 10 are arranged in sequence along the gas transmission direction.

[0059] A second pressure regulating valve 11 and a second pressure gauge 12 are sequentially arranged on the second gas transmission pipeline 4 along the gas transmission direction.

[0060] A second electromagnetic cut-off valve 13, a third pressure regulating valve 14, a third pressure gauge 15, and a second check valve 16 are sequentially arranged on the third gas transmission pipeline 5 along the gas transmission direction. By adjusting the third pressure regulating valve 14, the pressure is adjusted so as to adjust the vibration intensity of the vibrator 1 as required.

[0061] Combined with Figure 2 As shown, the feeding unit 300 includes a step feeder 17, and the step feeder 17 includes a feeder, a blanking pipe 18, a feeding cup 19, and a variable frequency motor 20.

[0062] The feeder is communicated with the powder spraying tank body 100.

[0063] The upper end of the blanking pipe 18 is communicated with the powder outlet of the feeder.

[0064] The feeding cup 19 is arranged in the blanking pipe 18.

[0065] The output shaft of the variable frequency motor 20 is connected to the feeding cup 19.

[0066] When the powder in the powder spraying tank body 100 is pressed into the feeding cup 19 under the action of the pressure in the tank, the feeding cup 19 is filled with the powder. At this time, the variable frequency motor 20 drives the feeding cup 19 to rotate to the reverse direction of the shaft, so that the opening of the feeding cup 19 faces downward, causing the powder in the feeding cup 19 to break away from the feeding cup 19 and fall within the range of the spraying unit 400. At this time, under the action of the conveying gas, the powder is sprayed into the reaction bath through the spraying nozzle. The feeding speed of the feeding unit 300 is determined by the rotation speed of the variable frequency motor 20. If the rotation speed of the variable frequency motor 20 is fast, the feeding speed is fast; otherwise, it is slow.

[0067] A third electromagnetic cut-off valve 21 is further arranged on the blanking pipe 18.

[0068] A sealing ring 22 is further arranged between the feeding cup 19 and the inner wall of the blanking pipe 18.

[0069] Combined with Figure 3 As shown, the spraying unit 400 includes a booster with a double-layer sleeve structure.

[0070] The air inlet of the booster is communicated with the third gas transmission pipeline 5.

[0071] An outer sleeve 23 and a central sleeve 24 arranged in the outer sleeve 23 are communicated with the air outlet of the booster.

[0072] The outlet side of the central sleeve 24 is located at the front end of the outlet side of the blanking pipe 18, and the outlet side of the outer sleeve 23 is located at the rear end of the outlet side of the blanking pipe 18.

[0073] During the experiment, due to the slow flow rate of the conveying gas, the negative pressure at the blanking end of the feeding unit 300 is small, and it is not easy to suck the powder into the argon injection area at the front end of the injector through the negative pressure generated by the gas, resulting in powder accumulation at the lower end of the feeder. In view of this, the present invention adds an injection unit 400 at the rear end of the original feeding unit 300. When the powder coming down from the blanking pipe 18 is pushed by the boosting gas of the injection unit 400 and sent to the argon jet area of the central pipe of the injector, the powder is directly blown into the molten iron by the argon jet, which is beneficial to the smooth progress of the injection.

[0074] The annular gap between the central sleeve 24 and the outer sleeve 23 is filled with the propulsion gas. The powder coming down from the blanking pipe 18 is pushed by the propulsion gas in the annular gap area and sent into the discharge pipe 500 at the front end of the feeding unit 300. Then, under the action of the front-end gas, the powder is sprayed into the reactor through the spray nozzle.

[0075] The feeding speed of the feeder is controlled by the feeding controller, and the rotation speed of the feeder determines the feeding speed. The feeder is coaxially connected to the variable-frequency motor, and the rotation speed of the variable-frequency speed-regulating motor determines the rotation speed of the feeder. The rotation speed of the variable-frequency motor is determined by the frequency of the frequency converter. The frequency conversion range of the frequency converter is 5HZ - 50HZ, and the output rotation speed of the corresponding frequency-modulated motor is 5r / min - 50r / min. Therefore, after calibrating the motor output rotation speed and the powder injection amount, 0.5 kg of powder that needs to be sprayed into the furnace each time can be sprayed into the furnace according to the set time.

[0076] The discharge pipe 500 is connected to the induction furnace through the powder conveying pipeline, and a suspended bottom-blowing powder injection element is provided at the powder outlet of the powder conveying pipeline.

[0077] Combined Figure 4 As shown, the suspended bottom-blowing powder injection element includes a powder injection element head 25 and a powder inlet pipe 26.

[0078] The powder injection element head 25 is connected to the powder outlet of the powder conveying pipeline.

[0079] A suspended air chamber 27 is provided inside the powder injection element head 25.

[0080] One end of the powder inlet pipe 26 is connected to the suspended air chamber 27, and the other end faces the molten iron in the induction furnace.

[0081] When the powder sprayed into the suspended air chamber 27 of the suspended bottom-blowing powder injection element is fully suspended, the powder is then sprayed into the molten iron in the furnace along with the carrier gas, without causing powder accumulation and blocking the gas supply element.

[0082] Example

[0083] The desulfurization test results (mass%) after using the hot-state test system and the desulfurization test results (mass%) without using the hot-state test system in this example are compared as follows in the table

[0084] Example Comparative Example Specimen Number Sampling Time S S 1# (Initial Sample) 0 0.102 0.113 2# (Process Sample) 10 0.094 0.101 3# (Process Sample) 20 0.083 0.091 4# (Process Sample) 30 0.075 0.078 5# (Process Sample) 40 0.062 0.072 6# (Process Sample) 50 0.052 0.066 7# (Process Sample) 60 0.039 0.061 Desulfurization Rate 61.8％ 46％

[0085] In summary, the present invention first determines a reasonable technical solution on the basis of fully considering the thermodynamics and kinetics theories of hot metal desulfurization and combining the basic characteristics of melting hot metal in an induction furnace, and designs and manufactures an experimental system device that can be used for bottom-blowing powder injection in an induction furnace for hot metal desulfurization. The desulfurization powder after fluidization treatment is loaded into the powder injection tank, and through the carrier gas, it passes through the powder injector and the corresponding pipeline, and then through a special gas supply component, and is sprayed into the hot metal in the furnace through the bottom of the induction furnace for desulfurization.

[0086] Those of ordinary skill in the art in this technical field should recognize that the above embodiments are only used to illustrate the present invention and are not used as a limitation to the present invention. As long as it is within the scope of the spirit of the present invention, the changes and modifications to the above embodiments will fall within the scope of the claims of the present invention.

Claims

1. A hot-state test system for desulfurization by bottom-blowing lime powder, characterized in that: it includes a powder spraying tank body, a gas supply unit, a feeding unit and a spraying unit; the gas supply unit is respectively communicated with the powder spraying tank body and the spraying unit; the powder spraying tank body is communicated with the feeding unit; the feeding unit is communicated and converged with the spraying unit, and then communicated with a discharge pipe.

2. The hot-state test system for desulfurization by bottom-blowing lime powder according to claim 1, characterized in that: the volume of the powder spraying tank body is 8 to 20 liters; a vibrator is arranged at the middle position of the powder spraying tank body.

3. The hot-state test system for desulfurization by bottom-blowing lime powder according to claim 2, characterized in that: the gas supply unit includes an intake main pipe and a first gas transmission pipeline, a second gas transmission pipeline and a third gas transmission pipeline communicated with the intake main pipe; the first gas transmission pipeline is communicated with the upper position of the powder spraying tank body; the second gas transmission pipeline is communicated with the vibrator; the third gas transmission pipeline is communicated with the spraying unit.

4. The hot-state test system for desulfurization by bottom-blowing lime powder according to claim 3, characterized in that: a stop valve is arranged on the intake main pipe; a first electromagnetic cut-off valve, a first pressure regulating valve, a first pressure gauge and a first check valve are successively arranged on the first gas transmission pipeline along the gas transmission direction; a second pressure regulating valve and a second pressure gauge are successively arranged on the second gas transmission pipeline along the gas transmission direction; a second electromagnetic cut-off valve, a third pressure regulating valve, a third pressure gauge and a second check valve are successively arranged on the third gas transmission pipeline along the gas transmission direction.

5. The hot-state test system for desulfurization by bottom-blowing lime powder according to claim 4, characterized in that: the feeding unit includes a step feeder; the step feeder includes a feeder, a blanking pipe, a feeding cup and a variable-frequency motor; the feeder is communicated with the powder spraying tank body; the upper end of the blanking pipe is communicated with the powder outlet of the feeder; the feeding cup is arranged in the blanking pipe; the variable-frequency motor is connected with the feeding cup.

6. The hot-state test system for desulfurization by bottom-blowing lime powder according to claim 5, characterized in that: a third electromagnetic cut-off valve is further arranged on the blanking pipe.

7. The hot-state test system for desulfurization by bottom-blowing lime powder according to claim 5, characterized in that: a sealing ring is further arranged between the feeding cup and the inner wall of the blanking pipe.

8. The hot-state test system for desulfurization by bottom-blowing lime powder according to claim 5, characterized in that: the spraying unit includes a booster with a double-layer sleeve structure; the air inlet of the booster is communicated with the third gas transmission pipeline; an outer sleeve and a central sleeve arranged in the outer sleeve are communicated with the air outlet of the booster; the outlet side of the central sleeve is located at the front end of the outlet side of the blanking pipe, and the outlet side of the outer sleeve is located at the rear end of the outlet side of the blanking pipe.

9. The hot-state test system for desulfurization by bottom-blowing lime powder according to claim 1, characterized in that: the discharge pipe is communicated into an induction furnace through a powder conveying pipeline; A suspension bottom-blowing powder injection element is provided at the powder outlet of the powder delivery pipeline.

10. The hot-state test system for bottom-blowing lime powder desulfurization according to claim 9, characterized in that: the suspension bottom-blowing powder injection element includes a powder injection element head and a powder inlet pipe; the powder injection element head is communicated with the powder outlet of the powder delivery pipeline; a suspension air chamber is arranged inside the powder injection element head; one end of the powder inlet pipe is communicated with the suspension air chamber, and the other end faces the molten iron in the induction furnace.

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