A method for controlling backflow ventilation

Abstract

This invention relates to the field of blast furnace ironmaking technology, and in particular to a method for controlling backflow shutdown. The method includes: before shutdown, notifying the dispatching room, hot blast stove, trough, injection station, blower station, TRT control room, gas plant management room, and soft water pump room to prepare; when slag and iron are basically removed, gradually reducing air pressure and stopping oxygen enrichment and coal supply; stopping the TRT; notifying the water handler to adjust the cooling water volume at the tuyeres; introducing steam and nitrogen at the furnace top; when switching from high pressure to atmospheric pressure, if the pressure difference is lower than normal, closing the cold air gate, switching the blast temperature control to manual, and stopping the hot blast stove; when the air pressure is reduced to approximately 0.04-0.05 MPa, contacting the gas plant management room to cut off the gas supply. Through standardized operating procedures, especially after fully opening the backflow valve, the hot gas is directed upwards into the backflow system by the chimney effect, creating negative pressure inside the furnace, effectively preventing gas from overflowing from the tuyeres and ensuring the safety of construction personnel.

Description

Technical Field

[0001] This invention relates to the field of blast furnace ironmaking technology, and in particular to a method for controlling backflow shutdown. Background Technology

[0002] Blast furnace ironmaking is one of the most important processes in modern steel production. During blast furnace production, when production needs to be interrupted due to equipment maintenance, accident handling, or other reasons, the blast furnace operation is usually stopped; this process is called a shutdown. Based on the duration of the shutdown, it can be divided into short-term and long-term shutdowns. Short-term shutdowns typically refer to shutdowns of less than 4 hours, mainly used for temporary operations such as replacing cooling equipment or repairing equipment; long-term shutdowns refer to shutdowns exceeding 4 hours, involving more complex maintenance tasks.

[0003] Whether it's a short-term or long-term shutdown, any maintenance involving the tuyeres platform area requires a backflow operation. The main purpose of the backflow operation is to remove the gas generated in the hearth, ensuring the safety of the construction personnel. Simultaneously, temperature control of the backflow system must be considered to protect the refractory materials at the hot blast duct and main hot blast pipe, ensuring the longevity and efficient operation of the blast furnace.

[0004] Equipment wear and tear: During the backflow shutdown process, if the temperature is not properly controlled, the refractory material of the hot air main pipe and its connection parts may crack or peel off due to excessive temperature difference, and may even cause the pipe shell to burn red and collapse, thus shortening the service life of the equipment.

[0005] Non-standard operation: Different ironmaking plants lack unified standards for backflow shutdown operation, resulting in different operating methods and making it difficult to ensure consistent safety and equipment protection effects. Summary of the Invention

[0006] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0007] In view of the aforementioned problem that improper operation during the backflow ventilation shutdown process may lead to gas overflow from the vent, seriously threatening the lives of construction workers, this invention is proposed.

[0008] Therefore, the purpose of this invention is to provide a method for controlling backflow ventilation.

[0009] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for controlling backflow ventilation shutdown, comprising notifying the dispatching room, hot air furnace, trough, injection station, blower station, TRT control room, gas plant management room, and soft water pump room to prepare before ventilation shutdown;

[0010] When the slag and iron are basically removed, start to gradually reduce the air pressure, stop oxygen enrichment and coal, stop the TRT operation, and notify the water engineer to adjust the cooling water volume of the bad air outlet.

[0011] Steam and nitrogen are introduced through the top of the furnace;

[0012] When switching from high pressure to normal pressure, if the pressure difference is lower than the normal level, close the cold air valve, switch the air temperature control to manual, and stop the hot air furnace.

[0013] When the air pressure is reduced to about 0.04-0.05MPa, contact the gas plant management office to cut off the gas supply. The procedure is to open the furnace top vent valve first, and then close the dust collector gas shut-off valve.

[0014] While reducing the air pressure, check the operation of the tuyere. After confirming that the slag and iron have been completely discharged, block the iron tap. After confirming that there is no possibility of slag entering the tuyere, reduce the air pressure to zero.

[0015] Close the cold air valve and hot air valve of the blower furnace to release the exhaust gas;

[0016] Open 4-6 small covers of the vent sight glass, but do not open the large cover or the small covers of the vents that have been filled with slag;

[0017] Fully open the backflow valve to allow backflow;

[0018] Raise the probe to signal a halt to the wind;

[0019] During maintenance, constantly monitor the temperature of the air temperature thermocouple inside the hot air main duct and control this temperature range between 950-1250℃. If the temperature is too high, increase the number of small covers on the air vents that are opened; if the temperature is too low, reduce the number of small covers on the air vents that are opened.

[0020] As a preferred embodiment of the backflow shutdown control method of the present invention, the method involves opening 4-6 small covers of the air vents and adjusting the amount of air entering the hot air main duct by controlling the number of small covers opened, thereby controlling the temperature inside the hot air main duct between 950-1250℃, so as to reduce the impact of temperature difference on the refractory material inside the duct and extend the service life of the equipment.

[0021] As a preferred embodiment of the backflow ventilation control method of the present invention, after the backflow valve is fully opened, the hot gas enters the backflow pipe system upward by relying on the chimney effect, forming a negative pressure inside the furnace body, thereby preventing the gas from overflowing from the vent and ensuring the personal safety of construction personnel.

[0022] As a preferred embodiment of the backflow shutdown control method of the present invention, the method is particularly applicable to blast furnace ironmaking processes, especially backflow operations involving maintenance of the tuyeres platform area. Standardized operation can effectively prevent safety hazards caused by gas leakage, while protecting refractory materials from damage.

[0023] As a preferred embodiment of the backflow shutdown control method of the present invention, the method further includes dynamically adjusting the number of small vent covers opened during maintenance based on the temperature change inside the hot air main duct, so as to maintain the temperature inside the hot air main duct within a stable range, reduce the temperature difference with normal production, thereby effectively protecting the refractory materials of the hot air main duct and its connecting parts, and extending the service life of the hot air main duct.

[0024] As a preferred embodiment of the reverse flow shutdown control method of the present invention, the following steps are taken: while reducing the air volume, the working condition of the tuyere is checked, and the iron outlet is blocked after confirming that the slag and iron have been completely discharged. After confirming that there is no possibility of slag filling into the tuyere, the air pressure is reduced to zero to ensure the safety of the shutdown process.

[0025] As a preferred embodiment of the backflow shutdown control method of the present invention, the cold air valve and hot air valve of the blower furnace are closed to release the exhaust gas, ensuring that there are no residual harmful gases in the furnace, thereby further improving safety.

[0026] As a preferred embodiment of the backflow shutdown control method of the present invention, when the air pressure is reduced to about 0.04-0.05MPa, the gas cut-off operation is carried out after contacting the gas plant management office. It is required to open the furnace top vent valve first, and then close the dust collector gas shut-off valve to ensure safe gas discharge and prevent gas accumulation from causing safety accidents.

[0027] As a preferred embodiment of the backflow shutdown control method of the present invention, steam and nitrogen are introduced through the furnace top to dilute the gas concentration in the furnace and further improve the safety factor.

[0028] As a preferred embodiment of the backflow shutdown control method of the present invention, the method further includes periodically checking the status of the air outlet cover during maintenance to ensure that it can be opened or closed in a timely manner when needed to adapt to different temperature changes and ensure that the temperature in the hot air main pipe is always within the range of 950-1250℃.

[0029] The beneficial effects of this invention are as follows: Through standardized operating procedures, especially after fully opening the backflow valve, this invention utilizes the chimney effect to allow hot gas to rise into the backflow pipe system, creating negative pressure inside the furnace and effectively preventing gas from overflowing from the tuyeres, thus ensuring the safety of construction personnel. By controlling the number of small tuyeres opened and adjusting the amount of air entering the hot air main pipe, the temperature inside the hot air main pipe is controlled between 950-1250℃, reducing the impact of temperature differences on refractory materials, effectively preventing cracking and spalling of the refractory materials, and extending the service life of the hot air main pipe and its connecting parts. The backflow shutdown control method of this invention is simple and efficient to operate, enabling shutdown operations to be completed in a short time, reducing production interruption time and improving production efficiency. This invention provides a standardized backflow shutdown operation procedure, ensuring clear guidance and standards for each ironmaking plant when performing backflow shutdown operations, improving operational consistency and reliability. By precisely controlling the temperature inside the hot air main pipe, equipment damage caused by excessive temperature differences is reduced, maintenance costs are lowered, and the service life of equipment is extended. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0031] Figure 1 This is a schematic diagram of the overall process of a reverse flow shutdown control method.

[0032] Figure 2 This is a schematic diagram of the positional structure between the casing pipe and the blast furnace in a backflow shutdown control method.

[0033] Figure 3 for Figure 2 The enlarged view at point A in the figure is a schematic diagram of the positional structure between the probe and the blast furnace. Detailed Implementation

[0034] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0035] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0036] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0037] Secondly, the present invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not according to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In addition, actual fabrication should include the three-dimensional spatial dimensions of length, width, and depth.

[0038] Example 1, referring to Figures 1-3 This is the first embodiment of the present invention, which provides a method for controlling backflow ventilation shutdown. This embodiment mainly describes the basic steps of backflow ventilation shutdown control, including pre-shutdown notification preparation, gradual reduction of airflow and pressure, introduction of steam and nitrogen at the furnace top, operation during the transition from high pressure to atmospheric pressure, gas cutting operation when the air pressure drops to a specific value, reducing air pressure to zero, closing the hot and cold air valves to release exhaust gas, opening the small cover of the tuyeres' sight glass, fully opening the backflow valve for backflow, and raising the probe to issue a shutdown signal. These steps constitute the basic framework of backflow ventilation shutdown control, clarify the basic operating procedures, provide a reliable starting point for subsequent embodiments, and ensure that all necessary safety measures are implemented.

[0039] Step 1: Before shutting down the blast furnace, notify the dispatch room, hot air furnace, blast furnace, injection station, blower station, TRT control room, gas plant management room, and soft water pump room to prepare.

[0040] Step 2: When the slag and iron are basically removed, start to gradually reduce the air pressure, stop oxygen enrichment and coal, stop the TRT operation, and notify the water inspector to adjust the cooling water volume of the bad air outlet.

[0041] Step 3: Pass steam and nitrogen through the furnace top;

[0042] Step 4: When switching from high pressure to normal pressure, if the pressure difference is lower than the normal level, close the cold air valve, switch the air temperature control to manual, and stop the hot air furnace.

[0043] Step 5: When the air pressure is reduced to about 0.04-0.05MPa, contact the gas plant management office to cut off the gas supply. The procedure is to open the furnace top vent valve first, and then close the dust collector gas shut-off valve.

[0044] Step 6: While reducing the air pressure, check the operation of the tuyere. After confirming that the slag and iron have been completely discharged, block the iron tap. After confirming that there is no possibility of slag entering the tuyere, reduce the air pressure to zero.

[0045] Step 7: Close the cold air valve and hot air valve of the blower furnace to release the exhaust gas;

[0046] Step 8: Open the small covers of 4-6 vent sight glasses. Do not open the large covers or the small covers of vents that have been filled with slag.

[0047] Step 9: Fully open the backflow valve to backflow;

[0048] Step 10: Raise the probe to signal a halt to the wind.

[0049] Step 11: During the maintenance process, pay close attention to the temperature of the air temperature thermocouple inside the hot air main pipe and control this temperature range between 950-1250℃. If the temperature is too high, increase the number of small covers on the air vents that are opened; if the temperature is too low, decrease the number of small covers on the air vents that are opened.

[0050] Furthermore, open 4-6 small covers on the air vents. By controlling the number of small covers on the air vents that are opened, the amount of air entering the hot air main duct can be adjusted, thereby controlling the temperature inside the hot air main duct between 950-1250℃. This reduces the impact of temperature differences on the refractory material inside the duct and extends the service life of the equipment.

[0051] Furthermore, after the backflow valve is fully opened, the hot gas is forced upward into the backflow pipe system by the chimney effect, forming a negative pressure inside the furnace body, thereby preventing the gas from overflowing from the tuyeres and ensuring the personal safety of construction personnel.

[0052] Furthermore, the method is particularly applicable to blast furnace ironmaking processes, especially backflow operations involving maintenance of the tuyeres platform area. Standardized operation can effectively prevent safety hazards caused by gas leaks, while protecting refractory materials from damage.

[0053] Furthermore, the method also includes dynamically adjusting the number of small covers opened during the maintenance process based on the temperature changes inside the hot air main duct, in order to maintain the temperature inside the hot air main duct within a stable range, reduce the temperature difference with normal production, thereby effectively protecting the refractory materials of the hot air main duct and its connecting parts, and extending the service life of the hot air main duct.

[0054] Furthermore, while reducing the air pressure, check the operation of the tuyere. After confirming that the slag and iron have been completely discharged, block the iron tap. After confirming that there is no possibility of slag filling the tuyere, reduce the air pressure to zero to ensure the safety of the shutdown process.

[0055] Furthermore, close the cold air valve and hot air valve of the blower furnace to release the exhaust gas and ensure that there are no residual harmful gases in the furnace, thereby further improving safety.

[0056] Furthermore, when the wind pressure is reduced to around 0.04-0.05 MPa, the gas supply should be cut off after contacting the gas plant management office. The gas supply should be cut off after opening the furnace top vent valve and then closing the dust collector gas shut-off valve to ensure safe gas discharge and prevent gas accumulation from causing safety accidents.

[0057] Furthermore, steam and nitrogen are introduced through the furnace top to dilute the gas concentration inside the furnace, further improving the safety factor.

[0058] Furthermore, the method also includes regularly checking the condition of the air vent covers during maintenance to ensure they can be opened or closed promptly when needed to adapt to different temperature changes and ensure that the temperature inside the hot air main duct remains within the range of 950-1250℃.

[0059] Example 2, refer to Figures 1-3 This is the second embodiment of the present invention. The difference between this embodiment and the first embodiment is that the safety-enhanced backflow shutdown control method ensures that the gas does not leak and prevents accidents from occurring through a series of specific steps.

[0060] Notification before shutdown: Notify the dispatch room, hot air furnace, trough, injection station, blower station, TRT control room, gas plant management room, and soft water pump room to prepare in advance.

[0061] Gradually reduce air and pressure: When the slag and iron are basically discharged, start to gradually reduce air and pressure, stop oxygen enrichment and coal, stop the TRT operation, and notify the water inspector to adjust the cooling water volume of the bad air outlet.

[0062] Steam and nitrogen are introduced into the furnace top: Steam and nitrogen are introduced to dilute the gas concentration in the furnace and further improve the safety factor.

[0063] High pressure to normal pressure: When switching from high pressure to normal pressure, if the pressure difference is lower than the normal level, close the cold air valve, switch the air temperature control to manual, and stop the hot air furnace.

[0064] When the air pressure is reduced to 0.04-0.05MPa, contact the gas plant management office to cut off the gas supply. First, open the furnace top vent valve, then close the dust collector gas shut-off valve to ensure safe gas discharge and prevent gas accumulation from causing safety accidents.

[0065] Check the operation of the tuyere: While reducing the air volume, check the operation of the tuyere. After confirming that the slag and iron have been completely discharged, block the iron tap. After confirming that there is no possibility of slag filling into the tuyere, reduce the air volume to zero to ensure the safety of the shutdown process.

[0066] Close relevant valves: Close the cold air valve and hot air valve of the blast furnace to release the exhaust gas and ensure that there are no residual harmful gases in the furnace, thereby further improving safety.

[0067] Fully open backflow valve: After the backflow valve is fully open, the hot gas is forced upward into the backflow pipe system by the chimney effect, forming a negative pressure inside the furnace body, thereby preventing the gas from overflowing from the tuyeres and ensuring the personal safety of construction personnel.

[0068] Regularly check the condition of the air vent covers: During maintenance, regularly check the condition of the air vent covers to ensure that they can be opened or closed in a timely manner when needed to adapt to different temperature changes and ensure that the temperature inside the hot air main duct is always within the range of 950-1250℃.

[0069] The rest of the structure is the same as in Example 1.

[0070] Example 3, referring to Figures 1-3 This is the third embodiment of the present invention. The difference between this embodiment and the previous embodiment is that the backflow shutdown control method for equipment protection and life extension is to reduce the impact of temperature difference on refractory materials by precisely controlling the temperature in the hot air main pipe.

[0071] Notification before shutdown: Notify the dispatch room, hot air furnace, trough, injection station, blower station, TRT control room, gas plant management room, and soft water pump room to prepare in advance.

[0072] Gradually reduce air and pressure: When the slag and iron are basically discharged, start to gradually reduce air and pressure, stop oxygen enrichment and coal, stop the TRT operation, and notify the water inspector to adjust the cooling water volume of the bad air outlet.

[0073] Steam and nitrogen are introduced into the furnace top: Steam and nitrogen are introduced to dilute the gas concentration in the furnace and further improve the safety factor.

[0074] High pressure to normal pressure: When switching from high pressure to normal pressure, if the pressure difference is lower than the normal level, close the cold air valve, switch the air temperature control to manual, and stop the hot air furnace.

[0075] When the air pressure is reduced to 0.04-0.05MPa, contact the gas plant management office to cut off the gas supply. First, open the furnace top vent valve, then close the dust collector gas shut-off valve to ensure safe gas discharge and prevent gas accumulation from causing safety accidents.

[0076] Open the small sight glass covers of the air vents: Open 4-6 small sight glass covers of the air vents. By controlling the number of small sight glass covers opened, the amount of air entering the hot air main duct can be adjusted, thereby controlling the temperature inside the hot air main duct between 950-1250℃, so as to reduce the impact of temperature difference on the refractory material inside the duct and extend the service life of the equipment.

[0077] Dynamically adjust the number of air vent covers to be opened: During maintenance, pay close attention to the temperature of the air temperature thermocouple in the hot air main duct and control this temperature range between 950-1250℃. When the temperature is too high, increase the number of air vent covers to be opened; when the temperature is too low, decrease the number of air vent covers to be opened.

[0078] Regularly check the condition of the air vent covers: During maintenance, regularly check the condition of the air vent covers to ensure that they can be opened or closed in a timely manner when needed to adapt to different temperature changes and ensure that the temperature inside the hot air main duct is always within the range of 950-1250℃.

[0079] Close relevant valves: Close the cold air valve and hot air valve of the blast furnace to release the exhaust gas and ensure that there are no residual harmful gases in the furnace, thereby further improving safety.

[0080] Fully open backflow valve: After the backflow valve is fully open, the hot gas is forced upward into the backflow pipe system by the chimney effect, forming a negative pressure inside the furnace body, thereby preventing the gas from overflowing from the tuyeres and ensuring the personal safety of construction personnel.

[0081] Through Examples 2 and 3, the application and advantages of the backflow shutdown control method in different aspects can be more clearly demonstrated.

[0082] The rest of the structure is the same as in Example 2.

[0083] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for controlling backflow ventilation, characterized in that: The method includes the following steps: Before shutting down the blast furnace, notify the dispatch room, hot air furnace, sump, injection station, blower station, TRT control room, gas plant management room, and soft water pump room to make preparations. When the slag and iron are basically removed, start to gradually reduce the air pressure, stop oxygen enrichment and coal, stop the TRT operation, and notify the water engineer to adjust the cooling water volume of the bad air outlet. Steam and nitrogen are introduced through the top of the furnace; When switching from high pressure to normal pressure, if the pressure difference is lower than the normal level, close the cold air valve, switch the air temperature control to manual, and stop the hot air furnace. When the air pressure is reduced to 0.04-0.05MPa, contact the gas plant management office to cut off the gas supply. The procedure requires opening the furnace top vent valve first, and then closing the dust collector gas shut-off valve. While reducing the air pressure, check the operation of the tuyere. After confirming that the slag and iron have been completely discharged, block the iron tap. After confirming that there is no possibility of slag entering the tuyere, reduce the air pressure to zero. Close the cold air valve and hot air valve of the blower furnace to release the exhaust gas; Open 4-6 small covers of the vents; do not open the large covers or the small covers of the vents that have been filled with slag. Fully open the backflow valve to allow backflow; Raise the probe to signal a halt to the wind; During maintenance, constantly monitor the temperature of the air temperature thermocouple inside the hot air main duct and control this temperature range between 950-1250℃. If the temperature is too high, increase the number of small covers on the air vents that are opened; if the temperature is too low, reduce the number of small covers on the air vents that are opened.

2. The backflow shutdown control method as described in claim 1, characterized in that: After the backflow valve is fully opened, the hot gas is forced upward into the backflow pipe system by the chimney effect, creating a negative pressure inside the furnace.

3. The backflow shutdown control method as described in claim 2, characterized in that: The method also includes periodically checking the condition of the air vent covers during maintenance to ensure that they can be opened or closed in a timely manner when needed to adapt to different temperature changes and ensure that the temperature inside the hot air main pipe is always within the range of 950-1250℃.

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