Variable-frequency adjusting system of steelmaking dust removal fan

Abstract

The utility model relates to a variable-frequency adjusting system of a steelmaking dust removal fan. The variable-frequency adjusting system comprises a smoke sensor, a pressure sensor, two temperature sensors, a flow sensor, a PLC (Programmable Logic Controller), a frequency converter and a man-machine interaction device, the smoke sensor is used for detecting smoke components and the smoke amount in the dust removal pipeline. The pressure sensor is used for detecting the pressure in the dust removal pipeline. The two temperature sensors are used for measuring the temperature of smoke in the smoke suction pipeline and the dust removal pipeline. The flow sensor is used for detecting the flow of flue gas in the dust removal pipeline. The man-machine interaction device is used for inputting parameters to the PLC. The PLC is used for obtaining the automatic target frequency of the dust removal fan according to the parameters and sending a control instruction to the frequency converter according to the automatic target frequency. The frequency converter is used for responding to the control instruction and adjusting the frequency of the dust removal fan to the automatic target frequency. The system can reduce the power consumption of the dust removal fan and reduce the production cost.

Description

Technical Field

[0001] This utility model relates to the technical field of frequency regulation of steelmaking dust removal fans, and in particular to a frequency conversion regulation system for steelmaking dust removal fans. Background Technology

[0002] In the steel smelting industry, the efficiency and intelligence level of dust removal systems directly affect the production environment, resource consumption, and enterprise cost management.

[0003] In existing technologies, dust removal systems in steel smelting still employ fixed-frequency operation or control methods based on simple thresholds. These methods have the following drawbacks:

[0004] Energy waste (fixed frequency problem): Many traditional dust removal systems still operate at high power during periods of low flue gas and dust generation. This results in unnecessary energy consumption by the equipment when flue gas and dust concentrations are low, leading to energy waste and increased production costs.

[0005] Response hysteresis (threshold triggering mechanism): In control methods based on simple thresholds, when the flue gas volume is high and the dust concentration exceeds the standard, the system will increase the frequency of the inverter. However, due to physical reactions and system execution time, dust diffusion often occurs, and simply increasing the frequency may not be able to control the dust concentration in a timely and effective manner, thereby affecting environmental quality and worker health.

[0006] Lack of global optimization (single indicator): Traditional systems fail to comprehensively consider multiple factors in the smelting process, such as the impact of different smelting stages, production processes, and rhythms on dust generation. This single indicator control method cannot achieve overall system optimization, often leading to local optima but low overall efficiency. Utility Model Content

[0007] To solve the above-mentioned technical problems, this utility model provides a frequency conversion regulation system for a steelmaking dust removal fan.

[0008] The frequency conversion control system for the steelmaking dust removal fan provided by this utility model adopts the following technical solution:

[0009] A variable frequency drive (VFD) system for a steelmaking dust collector fan is disclosed for VFD control of a dust collector fan in an AOD (Alternating Oxygen Depletion) furnace. The AOD furnace includes a base, furnace body, furnace frame, fume hood, dust collection chamber, and VFD fan. The furnace body is mounted on the base via the furnace frame. The fume hood inlet is located directly above the furnace body for extracting flue gas from the furnace. The fume hood outlet is connected to the dust collection chamber inlet via a smoke extraction pipe. The dust collection chamber outlet is connected to the VFD fan via a dust collection pipe. Driven by the VFD fan, the flue gas from the furnace passes through the fume hood, smoke extraction pipe, dust collection chamber, dust collection pipe, and VFD fan. The system includes: a flue gas sensor, a pressure sensor, two temperature sensors, a flow sensor, a PLC controller, a frequency converter, and a human-machine interface device; wherein, the flue gas sensor is installed on the fume hood and is used to detect the composition and amount of flue gas in the dust removal duct; the pressure sensor is installed in the dust removal chamber and is used to detect the pressure in the dust removal duct; the two temperature sensors are respectively installed on the smoke extraction duct and the dust removal duct and are used to measure the temperature of the flue gas in the smoke extraction duct and the dust removal duct, respectively; The flow sensor is installed on the dust removal duct to detect the flow rate of flue gas within the duct. The flue gas sensor, pressure sensor, temperature sensor, and flow sensor are all communicatively connected to the PLC controller and the human-machine interface device. The human-machine interface device is communicatively connected to the PLC controller and is used to input the target steel grade, the current smelting stage of the molten steel, the initial carbon content, the target carbon content, the initial nitrogen content, and the target nitrogen content into the PLC controller. The PLC controller is communicatively connected to the frequency converter and is used to derive the automatic target frequency of the dust removal fan based on the flue gas composition, smoke volume, pressure, flue gas flow rate, and the temperatures at the inlet and outlet of the dust removal duct, as well as the target steel grade, the smelting stage, the initial carbon content, the target carbon content, the initial nitrogen content, and the target nitrogen content. It then sends a control command to the frequency converter based on the automatic target frequency. The frequency converter responds to the control command and adjusts the frequency of the dust removal fan to the automatic target frequency.

[0010] Optionally, the human-machine interface device is communicatively connected to the frequency converter and is also used to manually control the frequency of the dust collector fan; during manual control, the human-machine interface device sends a control command to the frequency converter to adjust the frequency of the dust collector fan to the manual target frequency; the manual target frequency is derived from the manual reference frequency, the manual dust correction frequency, and the manual negative pressure correction frequency.

[0011] Optionally, it also includes an extension rod; the extension rod is disposed on the outer wall of the fume hood and is horizontally disposed; the flue gas sensor is disposed at the end of the extension rod away from the fume hood and points downward toward the upper side of the furnace body.

[0012] Optionally, the system further includes an industrial control computer; the industrial control computer is communicatively connected to the PLC controller; and the human-machine interface device is integrated into the industrial control computer.

[0013] Optionally, the communication connection includes a wired connection and / or a wireless connection.

[0014] Optionally, the PLC controller and the frequency converter communicate using PROFINET or Modbus.

[0015] Optionally, the industrial computer and the PLC controller communicate via EtherNet / IP.

[0016] As described above, the frequency conversion control system of the steelmaking dust removal fan of this utility model has at least the following beneficial effects:

[0017] 1. The variable frequency control system of the dust collector fan of this utility model can adjust the frequency of the dust collector fan in real time according to parameters such as oxygen flow rate, nitrogen flow rate, argon flow rate, dust load, and negative pressure of the dust collector fan. This method enables the dust collector fan to operate at low frequency during the low flue gas and low dust stages of the steelmaking process, reducing the power consumption of the dust collector fan, reducing energy waste, and lowering production costs.

[0018] 2. The frequency of the dust collector fan is adjusted in real time based on parameters such as dust load and negative pressure of the dust collector fan, which can effectively control the dust concentration before dust spreads, thereby reducing the impact on environmental quality and the health of workers.

[0019] 3. The frequency conversion regulation system of the dust removal fan of this utility model adjusts the frequency of the dust removal fan globally based on parameters such as oxygen flow rate, nitrogen flow rate, argon flow rate, dust load, and negative pressure of the dust removal fan. This avoids the problem of local optimization and low overall efficiency caused by controlling the dust removal fan through a single index in the prior art. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the frequency conversion control system for the AOD furnace and the steelmaking dust removal fan.

[0021] Figure 2 This is a diagram of the variable frequency drive system for a steelmaking dust removal fan.

[0022] Reference numerals in the attached drawings: 1. Base; 2. Furnace body; 3. Furnace frame; 4. Furnace hood; 41. Extension rod; 5. Dust collection chamber; 6. Variable frequency fan; 7. Smoke extraction duct; 8. Dust collection duct; 9. Flue gas sensor; 10. Temperature sensor. Detailed Implementation

[0023] The following specific examples illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. This utility model can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this utility model. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. It should also be understood that the terminology used in the embodiments of this utility model is for describing specific implementation schemes and not for limiting the scope of protection of this utility model. Test methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or according to the conditions recommended by the respective manufacturers.

[0024] It should be understood that the structures, proportions, sizes, etc., illustrated in the accompanying drawings of this specification are merely for illustrative purposes to aid those skilled in the art and are not intended to limit the scope of implementation of this utility model. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of this utility model, should still fall within the scope of the technical content disclosed in this utility model. Furthermore, the terms such as "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity of description and are not intended to limit the scope of implementation of this utility model. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of implementation of this utility model.

[0025] This utility model discloses a frequency conversion control system for a dust removal fan in steelmaking, used for frequency conversion control of the dust removal fan in an AOD furnace.

[0026] Please refer to Figure 1 and Figure 2 An AOD (Argon-Oxygen Decarburization) furnace, also known as an argon-oxygen decarburization furnace, removes carbon from steel using argon and oxygen. An AOD furnace includes a base 1, a furnace body 2, a furnace frame 3, a fume hood 4, a dust collection chamber 5, and a variable frequency fan 6. The furnace body 2 is mounted on the base 1 via the furnace frame 3. The inlet of the fume hood 4 is located directly above the furnace body 2 and is used to extract flue gas from within the furnace body 2. The outlet of the fume hood 4 is connected to the inlet of the dust collection chamber 5 via a smoke extraction pipe 7. The outlet of the dust collection chamber 5 is connected to the variable frequency fan 6 via a dust collection pipe 8. Driven by the variable frequency fan 6, the flue gas in the furnace body 2 is discharged after passing through the fume hood 4, smoke extraction pipe 7, dust collection chamber 5, dust collection pipe 8, and variable frequency fan 6.

[0027] The variable frequency control system of the steelmaking dust removal fan of this utility model includes a flue gas sensor 9, a pressure sensor, a temperature sensor 10, a flow sensor, a PLC controller, a frequency converter, and a human-machine interface device.

[0028] The system includes a flue gas sensor 9 mounted on the fume hood 4 of the AOD furnace to detect the composition and amount of flue gas in the dust removal duct 8. A pressure sensor is mounted inside the dust removal chamber 5 of the AOD furnace to detect the pressure within the dust removal duct 8. Two temperature sensors 10 are mounted on the smoke extraction duct 7 and the dust removal duct 8 of the AOD furnace, respectively, to detect the temperature of the flue gas within these ducts. A flow sensor is mounted on the dust removal duct 8 of the AOD furnace to detect the flow rate of the flue gas within it. The flue gas sensor 9, pressure sensor, temperature sensor 10, and flow sensor are all communicatively connected to the PLC controller and the human-machine interface (HMI). The HMI is also communicatively connected to the PLC controller to input information such as the target steel grade, the current smelting stage of the molten steel, the initial carbon content, the target carbon content, the initial nitrogen content, and the target nitrogen content. The PLC controller communicates with the frequency converter to determine the automatic target frequency of the dust collector fan based on the flue gas composition, smoke volume, pressure, and flow rate within the dust collector duct 8, as well as the temperatures at the inlet and outlet of the duct 8, the target steel grade, smelting stage, initial carbon content, target carbon content, initial nitrogen content, and target nitrogen content. The PLC controller then sends control commands to the frequency converter based on the automatic target frequency. The frequency converter responds to these control commands by adjusting the frequency of the dust collector fan to the automatic target frequency.

[0029] In a preferred embodiment of this invention, an extension rod 41 is provided on the outer wall of the fume hood 4, and the extension rod 41 is horizontally positioned. A flue gas sensor 9 is located at the end of the extension rod 41 furthest from the fume hood 4, pointing downwards towards the upper side of the furnace body 2. Compared to placing the flue gas sensor 9 inside the fume hood 4, this reduces the influence of the flue gas sensor 9 on the flue gas flow.

[0030] The variable frequency control system of the steelmaking dust removal fan of this utility model also includes an industrial control computer. The industrial control computer is communicatively connected to the PLC controller. The human-machine interface device is integrated into the industrial control computer. Compared with ordinary computers, the industrial control computer is resistant to high temperatures, dust, moisture, and electromagnetic interference, and can operate stably under harsh conditions such as high temperature, high dust, and strong vibration in steelmaking. The industrial control computer, together with the human-machine interface device, can monitor various parameters in the smelting process in real time, allowing staff to understand the status of raw materials and equipment in a timely manner.

[0031] The communication connections mentioned in this embodiment include wired and / or wireless connections. In a preferred embodiment of this invention, the PLC controller and the frequency converter communicate using PROFINET or Modbus. PROFINET communication offers high real-time performance and determinism, enabling high-precision synchronization between the PLC controller and the frequency converter, allowing for more timely adjustment of the dust collector fan's frequency. Modbus communication, on the other hand, has a simple structure and lower development, configuration, and maintenance costs, thus contributing to cost savings.

[0032] In another preferred embodiment of this invention, the industrial computer and the PLC controller communicate via EtherNet / IP. EtherNet / IP communication offers strong compatibility and excellent real-time communication capabilities, which helps improve the real-time performance of data transmission between the industrial computer and the PLC controller, thereby optimizing the control effect of the PLC controller.

[0033] Specifically, the frequency conversion control system of the steelmaking dust removal fan of this utility model can control the dust removal fan through the following methods:

[0034] Obtain information on the target steel grade and the current smelting stage of the molten steel. Obtain the initial carbon and nitrogen content of the molten steel. Based on the smelting stage information, set the target carbon and nitrogen content of the molten steel. Calculate the required oxygen flow rate for smelting based on the initial and target carbon contents. Calculate the required nitrogen flow rate for smelting based on the initial and target nitrogen contents. Calculate the required argon flow rate for smelting based on the oxygen flow rate. Calculate the flue gas flow rate during smelting based on the oxygen, nitrogen, and argon flow rates. Control the frequency of the dust collector fan based on the flue gas flow rate.

[0035] Different target steel grades require different gas proportioning strategies during the smelting process. Taking conventional stainless steel, nitrogen-containing stainless steel, and high-carbon steel as examples, the gas proportioning strategies shown in the table below are adopted respectively. At the beginning of smelting, gas is blown into the molten steel according to the gas proportioning strategy. During the smelting process, the gas ratio can be dynamically adjusted according to the actual situation of the molten steel.

[0036]

[0037] The smelting process includes the main blowing period, refining period, and reduction period. The main blowing period involves blowing high-pressure oxygen into the molten iron at high temperature to oxidize impurities such as carbon, silicon, manganese, and phosphorus. Some of these impurities are oxidized to form gases such as carbon dioxide and carbon monoxide, while the rest enters the slag. The refining period further adjusts the composition of the molten steel, improving its purity. The reduction period further desulfurizes the molten steel in a reducing atmosphere, further adjusting its composition.

[0038] It should be noted that, depending on the smelting process, the smelting stage information also includes the melting period, oxidation period, etc. This embodiment describes the implementation of this utility model through three main stages: the main blowing period, the refining period, and the reduction period.

[0039] The flue gas during the main blowing period mainly consists of carbon dioxide, nitrogen, argon, carbon monoxide, and dust. Therefore, when the molten steel is in the main blowing period, the frequency of the dust removal fan during the main blowing period is calculated and adjusted using the following steps:

[0040] Specifically, the amount of oxygen blown in needs to be determined based on the amount of carbon that needs to be removed from the molten steel. Therefore, the required oxygen flow rate during the main blowing period of the molten steel can be calculated using the following formula:

[0041] ;

[0042] In the formula, This represents the initial carbon content of the molten steel. The target carbon content of molten steel; For the quality of molten steel; The oxygen utilization rate during the main blowing period is between 0.8 and 0.85.

[0043] Nitrogen alloying is required during the main blowing period, which involves introducing nitrogen gas into the molten steel to improve the material's mechanical properties and corrosion resistance. The required nitrogen flow rate during the main blowing period is calculated using the following formula:

[0044] ;

[0045] In the formula, This represents the initial nitrogen content of the molten steel. The target nitrogen content for molten steel; For the quality of molten steel; Nitrogen utilization rate during the main blowing period;

[0046] The main purpose of introducing argon gas into the molten steel during the main blowing period is to inhibit the oxidation of chromium. The required argon gas flow rate during the main blowing period can be calculated using the following formula:

[0047] ;

[0048] In the formula, Argon utilization rate, between 0.3 and 0.5;

[0049] The carbon monoxide flow rate during the main blowing period in the smelting process is calculated using the following formula:

[0050] ;

[0051] In the formula, The carbon monoxide formation rate during the main blowing period is between 0.6 and 0.9.

[0052] The dust load during the main blowing period is calculated using the following formula:

[0053] ;

[0054] In the formula, W represents the mass of molten steel; the splashing rate is between 1% and 3%.

[0055] The flue gas flow rate during the main blowing period is calculated using the following formula:

[0056] ;

[0057] The fundamental frequency of the dust collector fan is calculated using the following formula:

[0058] ;

[0059] The dust correction frequency is calculated using the following formula:

[0060] ;

[0061] The negative pressure correction frequency is calculated using the following formula, where negative pressure is the pressure difference between the inside of the dust collection duct and the outside:

[0062] ;

[0063] In the formula, The target negative pressure for the dust removal fan; This refers to the actual negative pressure of the dust removal fan;

[0064] Finally, calculate the frequency of the dust collector fan during the main blowing period according to the following formula, and adjust the frequency of the dust collector fan to match the frequency of the dust collector fan during the main blowing period:

[0065] .

[0066] With molten steel weighing 75 tons and nitrogen flow rate of 1200... Nitrogen flow rate is 300 Argon flow rate is 600 For example,

[0067] .

[0068] =38.53Hz.

[0069] If the actual measured dust load is 65 The target negative pressure of the dust collector fan is -50Pa, and the actual negative pressure is -40Pa. .

[0070] The above process aims to automatically adjust the frequency of the dust collector fan during the main blowing period based on the flow rates of oxygen, nitrogen, and argon, as well as the dust load and negative pressure of the dust collector fan. In practical applications, frequency control of the dust collector fan based on flue gas flow rate is manual adjustment, and manual adjustment is carried out according to the following rules: When the flue gas flow rate is between 2000... ~3500 At this time, the reference frequency of the dust collector fan is between 30Hz and 45Hz. The dust correction frequency is between 0Hz and 5Hz. When the flue gas flow rate is between 3500... ~5000 At this time, the reference frequency of the dust collector fan is between 45Hz and 50Hz. The dust correction frequency is between 5Hz and 10Hz. When the flue gas flow rate is greater than 5000... At this time, the reference frequency of the dust collector fan is locked at 50Hz. The dust correction frequency is 15Hz.

[0071] During the main blowing period, the carbon content of molten steel is reduced to a low level. In the refining period, deep decarburization is required to precisely control the carbon content within the target range. Therefore, a different gas proportioning strategy is needed compared to the main blowing period. Taking conventional stainless steel, nitrogen-containing stainless steel, and high-carbon steel as examples, the gas proportioning strategy at the beginning of the refining period is as follows:

[0072]

[0073] After selecting a reasonable gas ratio strategy, the frequency of the dust collector fan during the main blowing period is calculated through the following steps:

[0074] The required oxygen flow rate during the refining period for molten steel can be calculated using the following formula:

[0075] .

[0076] In the formula, This represents the initial carbon content of the molten steel. This represents the target carbon content of the molten steel. The quality of the molten steel. To improve efficiency, . T represents the temperature of the molten steel.

[0077] It should be noted that the molten steel can only enter the refining stage after the main blowing stage is completed. Therefore, the initial carbon content of the molten steel in the refining stage is the same as the carbon content of the molten steel after the main blowing stage is completed.

[0078] The required nitrogen flow rate during the refining period of molten steel can be calculated using the following formula:

[0079] .

[0080] The required argon flow rate during the main blowing period of molten steel can be calculated using the following formula:

[0081] .

[0082] In the formula, To improve argon utilization, .

[0083] The carbon monoxide flow rate during the refining phase of the smelting process is calculated using the following formula:

[0084] .

[0085] In the formula, The carbon monoxide formation rate during the refining period. .

[0086] The dust load during the refining period is calculated using the following formula:

[0087] .

[0088] In the formula, W represents the mass of molten steel. The splashing rate is between 0.5% and 1.5%.

[0089] The flue gas flow rate during the refining period is calculated using the following formula:

[0090] .

[0091] The fundamental frequency of the dust collector fan is calculated using the following formula:

[0092] .

[0093] The dust correction frequency is calculated using the following formula:

[0094] .

[0095] The negative pressure correction frequency is calculated using the following formula:

[0096] .

[0097] In the formula, The target negative pressure for the dust removal fan. This is the actual negative pressure of the dust removal fan.

[0098] Finally, the frequency of the dust collector fan during the refining period is calculated according to the following formula, and the frequency of the dust collector fan is adjusted to the frequency of the dust collector fan during the refining period:

[0099] .

[0100] Taking the refining of 75 tons of 304 stainless steel as an example, if =0.1%, =0.03%, molten steel temperature T=1670℃, substituting into the calculation, we get:

[0101] , , , , , .and then .

[0102] If the target negative pressure of the dust collector fan is -50Pa, and the actual negative pressure is -45Pa, then The final calculation yielded... .

[0103] If the dust removal fan operates at a fixed frequency of 40Hz during the refining period, it requires 7.2 kWh of electricity to smelt each ton of molten steel. However, if the aforementioned method is used to make the dust removal fan operate at a variable frequency, it requires about 4.5 kWh of electricity to smelt each ton of molten steel, reducing energy consumption by 37.5%.

[0104] The above process aims to automatically adjust the frequency of the dust collector fan during the refining period based on the flow rates of oxygen, nitrogen, and argon, as well as the dust load and negative pressure of the dust collector fan. In practical applications, frequency control of the dust collector fan based on flue gas flow rate is manual, and manual adjustment is performed according to the following rules: when the flue gas flow rate is between 500... ~800 During this period, the reference frequency of the dust collector fan is between 20Hz and 25Hz. The dust correction frequency is determined based on the amount of dust in the flue gas; for every 10mg / m³ increase in dust concentration in the flue gas... 3 The dust correction frequency increases by 0.5 Hz. The negative pressure correction frequency is determined by the negative pressure at the dust collector fan; for every 0.1 Pa decrease in negative pressure at the dust collector fan, the negative pressure correction frequency increases by 0.15 Hz. When the flue gas flow rate is between 800... ~1200 During this period, the reference frequency of the dust collector fan is between 25Hz and 35Hz. The dust correction frequency is determined based on the amount of dust in the flue gas; for every 10mg / m³ increase in dust concentration in the flue gas... 3 The dust correction frequency increases by 1 Hz. The negative pressure correction frequency is determined by the negative pressure at the dust collector fan; for every 0.2 Pa decrease in negative pressure at the dust collector fan, the negative pressure correction frequency increases by 0.2 Hz. When the flue gas flow rate is between 1200... ~2000 During this period, the reference frequency of the dust collector fan is between 35Hz and 45Hz. The dust correction frequency is determined based on the amount of dust in the flue gas; for every 10mg / m³ increase in dust concentration in the flue gas... 3The dust correction frequency increases by 2Hz. The negative pressure correction frequency is determined by the negative pressure at the dust collector fan; for every 0.3Pa decrease in negative pressure at the dust collector fan, the negative pressure correction frequency increases by 0.3Hz.

[0105] After the main blowing and refining stages, the molten steel undergoes a final reduction stage to protect the alloys in the steel and adjust the slag. At the beginning of the refining stage, different gas proportioning strategies are employed depending on the target steel grade.

[0106]

[0107] After selecting an appropriate gas ratio strategy, the frequency of the dust removal fan during the reduction period is calculated using the following steps:

[0108] The required argon flow rate for molten steel is calculated using the following formula. The argon flow rate is a guideline value for argon flow, reflecting the ideal demand for argon during the reduction period:

[0109] .

[0110] In the formula, To improve argon utilization, Between 1.0 and 1.2. The quality of the molten steel.

[0111] The actual flow rate of argon during the reduction period is based on the reference flow rate of argon. Precise control is achieved through corrections to ultimately ensure the optimal balance between process efficiency, safety, and cost.

[0112] The required nitrogen flow rate during the refining period of molten steel can be calculated using the following formula:

[0113] .

[0114] In the formula, This represents the target nitrogen content in the molten steel. This represents the current nitrogen content of the molten steel. The quality of the molten steel. Nitrogen utilization rate during the reduction period =0.5.

[0115] The required oxygen supplement for molten steel can be calculated using the following formula:

[0116] .

[0117] The dust load during the refining period is calculated using the following formula:

[0118] .

[0119] In the formula, W represents the mass of molten steel. The splashing rate is between 0.5% and 1.0%.

[0120] The hydrogen flow rate during the refining period is calculated using the following formula:

[0121] .

[0122] In the formula, This represents the amount of FeSi used during the reduction period.

[0123] The flue gas flow rate during the refining period is calculated using the following formula:

[0124] .

[0125] The fundamental frequency of the dust collector fan is calculated using the following formula:

[0126] .

[0127] The dust correction frequency is calculated using the following formula:

[0128] .

[0129] The negative pressure correction frequency is calculated using the following formula:

[0130] .

[0131] In the formula, The target negative pressure for the dust removal fan. This is the actual negative pressure of the dust removal fan.

[0132] Finally, the frequency of the dust collector fan is calculated and adjusted to the frequency of the dust collector fan during the main blowing period according to the following formula:

[0133] .

[0134] In the formula, To safely adjust the frequency, when hour, 50Hz, when hour, 10Hz.

[0135] If the gas ratio strategy is adopted =1:0:8, argon flow rate is 82.5 ,but Therefore, it can be calculated that... Corresponding If the actual dust concentration is 25 mg / m³ 3 The target negative pressure is -50 Pa, and the actual negative pressure is -45 Pa. .

[0136] The frequency control of the dust collector fan based on the flue gas flow rate is manually adjusted, and the manual adjustment is carried out according to the following rules: when the flue gas flow rate is between 0 and 100 rpm... ~500 During this period, the reference frequency of the dust collector fan is between 20Hz and 25Hz. The dust correction frequency is determined based on the amount of dust in the flue gas; for every 10mg / m³ increase in dust concentration in the flue gas... 3 The dust correction frequency increases by 0.5 Hz. The negative pressure correction frequency is determined by the negative pressure at the dust collector fan; for every 10 Pa decrease in negative pressure at the dust collector fan, the negative pressure correction frequency increases or decreases by 0.15 Hz. When the flue gas flow rate is between 500... ~1000 During this period, the reference frequency of the dust collector fan is between 25Hz and 35Hz. The dust correction frequency is determined based on the amount of dust in the flue gas; for every 10mg / m³ increase in dust concentration in the flue gas... 3 The dust correction frequency increases by 1 Hz. The negative pressure correction frequency is determined by the negative pressure at the dust collector fan; for every 10 Pa decrease in negative pressure at the dust collector fan, the negative pressure correction frequency increases or decreases by 0.2 Hz. When the flue gas flow rate is between 1000... ~2000 During this period, the reference frequency of the dust collector fan is between 35Hz and 50Hz. The dust correction frequency is determined based on the amount of dust in the flue gas; for every 10mg / m³ increase in dust concentration in the flue gas... 3 The dust correction frequency increases by 2Hz. The negative pressure correction frequency is determined by the negative pressure at the dust collector fan; for every 10Pa decrease in negative pressure at the dust collector fan, the negative pressure correction frequency increases or decreases by 0.3Hz.

[0137] Compared with existing technologies, the variable frequency control system of this invention can adjust the frequency of the dust collector fan in real time based on parameters such as oxygen flow rate, nitrogen flow rate, argon flow rate, dust load, and negative pressure. This method enables the dust collector fan to operate at low frequency during the low flue gas and low dust stages of the steelmaking process, reducing the power consumption of the dust collector fan, minimizing energy waste, and lowering production costs.

[0138] Secondly, by adjusting the frequency of the dust collector fan in real time based on parameters such as dust load and negative pressure, the dust concentration can be effectively controlled before dust spreads, thereby reducing the impact on environmental quality and the health of workers.

[0139] Furthermore, the variable frequency control system of the dust collector fan of this utility model adjusts the frequency of the dust collector fan globally based on parameters such as oxygen flow rate, nitrogen flow rate, argon flow rate, dust load, and negative pressure of the dust collector fan. This avoids the problem of local optimization and low overall efficiency caused by controlling the dust collector fan through a single index in the prior art.

[0140] The above embodiments are merely illustrative of the principles and effects of this utility model and are not intended to limit the scope of this utility model. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this utility model. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this utility model should still be covered by the claims of this utility model.

Claims

1. A variable frequency control system for a steelmaking dust removal fan, used for variable frequency control of a dust removal fan in an AOD furnace; the AOD furnace includes a base (1), a furnace body (2), a furnace frame (3), a fume hood (4), a dust removal chamber (5), and a variable frequency fan (6); the furnace body (2) is mounted on the base (1) via the furnace frame (3); the inlet of the fume hood (4) is located directly above the furnace body (2) for extracting flue gas from the furnace body (2); the outlet of the fume hood (4) is connected to the inlet of the dust removal chamber (5) via a smoke extraction pipe (7); the outlet of the dust removal chamber is connected to the variable frequency fan (6) via a dust removal pipe (8); driven by the variable frequency fan (6), the flue gas in the furnace body (2) is discharged after passing through the fume hood (4), the smoke extraction pipe (7), the dust removal chamber, the dust removal pipe (8), and the variable frequency fan (6); Its features are, The system includes: a flue gas sensor (9), a pressure sensor, two temperature sensors (10), a flow sensor, a PLC controller, a frequency converter, and a human-machine interface device; wherein, The flue gas sensor (9) is installed on the fume hood (4) and is used to detect the composition and amount of flue gas in the dust removal duct (8); The pressure sensor is installed inside the dust removal chamber (5) and is used to detect the pressure inside the dust removal pipe (8); The two temperature sensors (10) are respectively installed on the smoke extraction pipe (7) and the dust removal pipe (8) to measure the temperature of the flue gas in the smoke extraction pipe (7) and the dust removal pipe (8); The flow sensor is installed on the dust removal pipe (8) and is used to detect the flow rate of flue gas in the dust removal pipe (8); The flue gas sensor (9), the pressure sensor, the temperature sensor (10), and the flow sensor are all communicatively connected to the PLC controller and the human-machine interface device. The human-machine interface device is communicatively connected to the PLC controller and is used to input the target steel grade, the current smelting stage of the molten steel, the initial carbon content of the molten steel, the target carbon content, the initial nitrogen content, and the target nitrogen content into the PLC controller. The PLC controller is communicatively connected to the frequency converter and is used to determine the automatic target frequency of the dust removal fan based on the composition of the flue gas in the dust removal duct (8), the amount of smoke, the pressure, the flue gas flow rate, the temperature at the inlet and outlet of the dust removal duct (8), the target steel grade, the smelting stage, the initial carbon content, the target carbon content, the initial nitrogen content, and the target nitrogen content. The PLC controller also sends control commands to the frequency converter based on the automatic target frequency. The frequency converter is used to respond to the control command and adjust the frequency of the dust removal fan to the automatic target frequency.

2. The frequency conversion control system for the dust collector fan according to claim 1, characterized in that, The human-machine interface device is communicatively connected to the frequency converter and is also used to manually control the frequency of the dust collector fan. When manually controlled, the human-machine interface device sends a control command to the frequency converter to adjust the frequency of the dust collector fan to the manual target frequency. The manual target frequency is derived from the manual reference frequency, the manual dust correction frequency, and the manual negative pressure correction frequency.

3. The frequency conversion control system for the dust collector fan according to claim 1, characterized in that, It also includes an extension rod (41); the extension rod (41) is disposed on the outer wall of the fume hood (4) and is horizontally disposed; the flue gas sensor (9) is disposed at the end of the extension rod (41) away from the fume hood (4) and points downward toward the upper side of the furnace body (2).

4. The frequency conversion control system for the dust collector fan according to claim 1 or 2, characterized in that, The system also includes an industrial control computer; the industrial control computer is communicatively connected to the PLC controller; and the human-machine interface device is integrated into the industrial control computer.

5. The frequency conversion control system for the dust collector fan according to claim 4, characterized in that, The communication connection includes a wired connection and / or a wireless connection.

6. The frequency conversion control system for the dust collector fan according to claim 5, characterized in that, The PLC controller and the frequency converter communicate using PROFINET or Modbus.

7. The frequency conversion control system for the dust collector fan according to claim 5, characterized in that, The industrial computer and the PLC controller communicate via EtherNet / IP.

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