An operating method and system for improving the safety of shutdown of a large blast furnace

Abstract

This invention discloses an operating method and system for improving the safety of large blast furnace shutdown, relating to the technical field of blast furnace shutdown in ironmaking. The invention includes real-time monitoring of hydrogen and oxygen content within the blast furnace during the initial shutdown process; firstly, determining the P... O Is it greater than P? S Further judgment of P H Is it greater than P? Y , where P Y P represents the permissible hydrogen content in a blast furnace. H P represents the current hydrogen content inside the blast furnace. S P represents the permissible oxygen content in a blast furnace. O The current oxygen content inside the blast furnace is monitored; simultaneously, the furnace top temperature is monitored in real time; and T is determined. D Within the preset time period, it is located less than T. S Greater than T S And less than T Y The sum is greater than T Y And less than T D Within which range, and depending on the situation, cooling of the furnace can be achieved by atomizing water on the furnace top, adding coke to the surface, or reducing the air volume of the blower; this invention solves the problem of unstable oxygen and hydrogen content in the gas during existing blast furnace shutdowns, which can easily lead to explosions.

Description

Technical Field

[0001] This invention relates to the technical field of blast furnace shutdown in ironmaking, and more particularly to an operating method and system for improving the safety of large blast furnace shutdown. Background Technology

[0002] Modern blast furnace ironmaking is becoming increasingly large, with large blast furnaces generally developing into short and stout shapes with large internal dimensions and low height-to-diameter ratios. If maintenance or replacement of cooling walls or major overhauls are required, the furnace must be shut down. There are two main methods for shutting down the furnace: one is the filled furnace shutdown method, which has been gradually phased out due to the large amount of subsequent furnace dismantling work; the other is the empty charge line shutdown method, which has gradually become more popular because it facilitates maintenance work.

[0003] However, the empty charge line shutdown method has prominent safety issues. Due to the presence of explosive gases, the safety of the blast furnace body and gas pipeline network during the entire shutdown process is threatened. It is necessary to strictly control the top temperature, oxygen, and hydrogen content in the gas to prevent explosions. Summary of the Invention

[0004] In view of the problem that the oxygen and hydrogen content in the gas are unstable and prone to explosion when the existing blast furnace is shut down, the present invention is proposed.

[0005] Therefore, the purpose of this invention is to provide an operating method to improve the safety of large blast furnace shutdown, which aims to improve the safety of the shutdown process by real-time monitoring of the hydrogen and oxygen content in the blast furnace.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: an operation method for improving the safety of large blast furnace shutdown, comprising,

[0007] When the initial shutdown begins, the hydrogen and oxygen content inside the blast furnace is monitored in real time.

[0008] Determine P O Is it greater than P? S P H Is it greater than P? Y , where P Y P represents the permissible hydrogen content in a blast furnace. H P represents the current hydrogen content inside the blast furnace. S P represents the permissible oxygen content in a blast furnace. O This represents the current oxygen content inside the blast furnace.

[0009] At the same time, the furnace top temperature is monitored in real time;

[0010] When P O Less than P S If P H Less than P Y Then determine T D Is it less than T within the preset time? ST D T represents the current temperature inside the blast furnace. S If the temperature inside the blast furnace is low, the furnace will be stopped after the charge is introduced into the furnace, and the blower will be kept at maximum airflow.

[0011] If not, then determine T. D Is it greater than T within the preset time? S And less than T Y If so, increase the amount of water applied while continuing to cover the surface with charcoal.

[0012] If not, then determine T. D Is it greater than T within the preset time? Y And less than T B If so, reduce the fan airflow;

[0013] When P O Less than P S If P H Greater than P Y Then determine T D Is it less than T within the preset time? S If so, turn on the atomizing water dispenser and control it to reduce the amount of water dispensed;

[0014] If not, then determine T. D Is it greater than T within the preset time? S And less than T Y T Y The highest temperature for the first-stage cooling in the blast furnace is if so. If so, increase the amount of water applied while continuing to cover the surface with coke.

[0015] If not, then determine T. D Is it greater than T within the preset time? Y And less than T B T B If the maximum temperature for secondary cooling inside the blast furnace is reached, then reduce the air volume of the blower and the amount of water pumped.

[0016] When P O Greater than P S This reduces the air volume of the fan.

[0017] As a preferred embodiment of the operating method for improving the shutdown safety of large blast furnaces according to the present invention, wherein: P Y The value is 12% vol, P S The value is 1% vol.

[0018] As a preferred embodiment of the operation method for improving the shutdown safety of large blast furnaces according to the present invention, the maximum output air volume of the blower is 100%, and the total air volume is maintained at 80% to 90% in the early stage. When the blower air volume is reduced, the total air volume is reduced by 3% to 5% each time.

[0019] As a preferred embodiment of the operating method for improving the shutdown safety of large blast furnaces according to the present invention, the cover coke is a small-particle porous honeycomb structure, and its pores can absorb moisture to reach a water-saturated state.

[0020] As a preferred embodiment of the operating method for improving the shutdown safety of large blast furnaces according to the present invention, wherein: the T S The value is 280℃, and the T Y The value is 350℃, and the T B The value is 500℃.

[0021] As a preferred embodiment of the operating method for improving the shutdown safety of large blast furnaces according to the present invention, wherein: the cover coke is added to the furnace in batches, and the formula for calculating the amount used in each batch is:

[0022] T = 0.5πr²

[0023] Where T represents the total amount of coke added in each batch, π represents pi, and r represents the radius of the furnace throat.

[0024] As a preferred embodiment of the operation method for improving the safety of large blast furnace shutdown according to the present invention, wherein: the upper material line of the empty material line reaches 2-4m above the center line of the blast furnace tuyeres, and the blower is shut down.

[0025] As a preferred embodiment of the operation method for improving the safety of large blast furnace shutdown according to the present invention, the method involves adding a layer of coke to the furnace every 20 to 30 minutes.

[0026] As a preferred embodiment of the operation method for improving the shutdown safety of large blast furnaces according to the present invention, the atomizing water spraying device is set at the throat of the blast furnace, located below the gas cover, and its atomizing nozzles are arranged along the circumference of the inner wall of the blast furnace, and the number is an even number.

[0027] Another object of the present invention is to provide an operating system for improving the safety of large blast furnace shutdowns, which is applicable to the aforementioned operating methods for improving the safety of large blast furnace shutdowns, including:

[0028] The gas monitoring module is used to collect the current concentration of hydrogen and oxygen in the blast furnace in real time during the shutdown process;

[0029] The temperature monitoring module is used to monitor the stable changes in temperature inside the blast furnace in real time during the shutdown process;

[0030] The processing module, which is electrically connected to the atomizing water spraying device, the blower, the gas monitoring module, and the temperature monitoring module, is used to receive and determine the P during the blast furnace shutdown process. H Is it greater than P? Y P O Is it greater than P? S And further determine T D With T S T Y and T B The size relationship is determined and the result is sent to the control center, which then issues instructions to control the atomizing water spraying device to spray water and the fan to blow air.

[0031] The beneficial effects of this invention are:

[0032] This invention improves the safety of furnace shutdown and greatly reduces costs by real-time monitoring of hydrogen and oxygen content in different ranges and taking different cooling actions according to different situations. Attached Figure Description

[0033] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. 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 creative effort. Wherein:

[0034] Figure 1 This is a schematic diagram of the overall logic of the operation method for improving the shutdown safety of large blast furnaces according to the present invention.

[0035] Figure 2 This is a logical diagram illustrating one scenario in the shutdown process of the operation method for improving the shutdown safety of a large blast furnace according to the present invention.

[0036] Figure 3 This is a logical diagram illustrating another scenario during the shutdown process of the operation method for improving the shutdown safety of large blast furnaces according to the present invention.

[0037] Figure 4 This is a schematic diagram of the blast furnace structure, illustrating the operation method for improving the shutdown safety of large blast furnaces according to the present invention.

[0038] Figure 5 This is a schematic diagram of the operating system for improving the shutdown safety of large blast furnaces according to the present invention. Detailed Implementation

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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 three-dimensional spatial dimensions of length, width, and depth.

[0043] Example 1

[0044] Reference Figures 1-4 This is the first embodiment of the present invention, which provides an operating method to improve the safety of large blast furnace shutdown, including the following steps:

[0045] S1: When the furnace is initially shut down, monitor the hydrogen and oxygen content in the blast furnace in real time.

[0046] S11: Determine P O Is it greater than P? S P H Is it greater than P? Y , where P Y P represents the permissible hydrogen content in a blast furnace. H P represents the current hydrogen content inside the blast furnace. S P represents the permissible oxygen content in a blast furnace. O This represents the current oxygen content inside the blast furnace.

[0047] Among them, P Y The preferred value is 12% vol, P S The preferred value is 1% vol. When the hydrogen and oxygen content is less than this value, even under high-temperature heating in the furnace, the detonation phenomenon is unlikely to occur in the furnace because the hydrogen and oxygen concentration has not reached the dangerous critical value.

[0048] S2: Simultaneously, monitor the furnace top temperature in real time.

[0049] S21: When P O Less than P S If PH Less than P Y Then determine T D Is it less than T within the preset time? S T D T represents the current temperature inside the blast furnace. S If the temperature inside the blast furnace is low enough, the furnace will be stopped after the charge is introduced into the furnace, and the blower will be kept at maximum airflow.

[0050] Furthermore, firstly, ensure that the oxygen content inside the furnace is less than 1% vol. At this point, both the hydrogen and oxygen contents are below the detonation critical point. Specifically, T... S The preferred value is 280℃. When the furnace temperature is lower than this value, it means that the furnace temperature is within a safe range and the furnace environment is safe. Maintaining the furnace stoppage of the empty material line, keeping the blower airflow, increasing the gas flow rate in the furnace, accelerating the reaction of the shut-off material, and avoiding excessively long shutdown time.

[0051] S211: If not, then determine T D Is it greater than T within the preset time? S And less than T Y T Y This is the highest temperature for the first-stage cooling in the blast furnace. If so, increase the amount of water applied while continuing to cover the surface with coke.

[0052] Among them, T Y The preferred value is 350℃. At this temperature, the furnace temperature is higher than the safety threshold, but still within a controllable range. If the furnace temperature is allowed to continue to increase, there is a risk of instability and uncontrollability. Therefore, further cooling measures are needed.

[0053] Furthermore, it is necessary to increase the amount of water added and simultaneously add top coke to the furnace. This type of top coke is made of small, porous, honeycomb particles. Its pores can absorb water and reach a water saturation state. This ensures the cooling effect while avoiding excessive water addition, which would increase the hydrogen and oxygen content in the furnace.

[0054] Furthermore, during this process, the hydrogen and oxygen content in the furnace is monitored in real time using a gas monitoring device. When the hydrogen and oxygen content approaches the aforementioned values, the amount of water dispensed needs to be appropriately reduced.

[0055] S212: If not, then determine T D Is it greater than T within the preset time? Y And less than T B T B This is the highest temperature for the secondary cooling stage inside the blast furnace. If so, reduce the air volume of the blower.

[0056] At this point, the furnace temperature is within the maximum allowable safe range, T BThe preferred temperature is 500℃, but further forced intervention is needed to fundamentally cool the blast furnace. Therefore, the blower needs to be reduced to 30% of its maximum air volume, and the water spray volume of the water pumping device needs to be adjusted to 100-120t / h.

[0057] In such cases, the main method to assist in blast furnace cooling is to add coke to the furnace. Because the furnace temperature is too high, it is not advisable for the furnace to contain excessive hydrogen or oxygen. Cooling with coke that has reached a water saturation state can improve the safety of furnace shutdown.

[0058] S22: When P O Less than P S If P H Greater than P Y Then determine T D Is it less than T within the preset time? S If so, turn on the atomizing water dispenser and control it to reduce the amount of water dispensed.

[0059] Furthermore, since the oxygen content is less than the detonation value and the temperature is within a safe range, there is no need to worry too much about safety accidents. The normal empty material line is shut down, so the blower continues to maintain maximum airflow to continuously consume the shut-down material.

[0060] Furthermore, at this point, the oxygen content inside the furnace is within the safe threshold range, and the iron slag burns more completely, causing the furnace temperature to rise further. In order to offset the heat generated by the combustion of the iron slag and the shut-down charge, the temperature is maintained at T. D Less than T S Therefore, it is necessary to turn on the atomizing water spraying device to cool the furnace with a small water spray output.

[0061] S221: If not, then determine T D Is it greater than T within the preset time? S And less than T Y If so, increase the amount of water applied while continuing to cover the surface with charcoal.

[0062] Furthermore, at this point, the furnace temperature is above the safety threshold, but still within a controllable range. If the furnace temperature is allowed to continue to increase, there is a risk of instability and uncontrollability, so further cooling measures are needed.

[0063] Furthermore, since the oxygen content is within a safe range at this time, the amount of water added can be increased, and coke can be added to the furnace at the same time. In this process, the excess hydrogen and oxygen produced may accelerate the consumption of iron slag and shutdown materials, thus promoting the shutdown of the blast furnace.

[0064] S222: If not, then determine T D Is it greater than T within the preset time? Y And less than T BIf so, reduce the fan airflow and the amount of water pumped.

[0065] At this point, the furnace temperature is at the maximum allowable value within the safe range, and further mandatory intervention is required. The blast furnace needs to be cooled down fundamentally. Therefore, the blower needs to be reduced to 30% of its maximum air volume, and the water spray volume of the water pumping device needs to be adjusted to 100-120 t / h.

[0066] In such cases, it is necessary to monitor the hydrogen and oxygen content in the furnace in real time, and to assist in cooling the blast furnace by adding top coke to the furnace. Because the temperature inside the furnace is too high, the faster combustion efficiency combined with the top coke can quickly and effectively cool the blast furnace.

[0067] S23: When P O Greater than P S This reduces the air volume of the fan.

[0068] Furthermore, in this embodiment, the top priority is to ensure that the oxygen content is less than 1% vol. If it exceeds 1% vol, regardless of the temperature or hydrogen content, the ventilation must be reduced immediately. The second priority is to control the top temperature. It is acceptable to exceed 350°C for a short time, but the limit is 500°C. The third priority is to control the hydrogen content, with a limit of 12% vol.

[0069] Furthermore, higher oxygen content increases the probability of detonation inside the furnace, so it is necessary to constantly monitor the oxygen content inside the furnace. At the beginning of the shutdown of the empty charge line, if P... O Greater than P S The fan airflow needs to be reduced immediately.

[0070] Example 2

[0071] Reference Figures 1-4 This is the second embodiment of the present invention, which differs from the first embodiment in that: the cover coke is added to the furnace in batches, and the formula for calculating the amount used in each batch is as follows:

[0072] T = 0.5πr²

[0073] Where T represents the total amount of coke added in each batch, π represents pi, and r represents the radius of the furnace throat.

[0074] Preferably, the total amount of coke on the surface is determined by the volume of the furnace stop line from the center line of the tuyere, and the amount used per batch is determined by the furnace throat material distribution height of 0.5m, where the furnace throat radius is known, and the value of π is taken as 3.14, thus obtaining the total amount of coke on the surface of each batch.

[0075] When the upper material line of the empty material line reaches 2-4m above the center line of the blast furnace tuyeres, the blower should be shut down.

[0076] Furthermore, during the shutdown process, the point where the empty charge line meets the furnace waist and belly is generally where the softening zone gradually disappears. Before this point, oxygen has been shut off to ensure safety. After reaching this range, the gas resistance decreases significantly, and the hydrogen content in the gas reaches its peak, correspondingly increasing the risk of detonation. At this stage, the blast must be drastically reduced to lower the gas flow rate. The subsequent shutdown process will maintain a low blast volume and no oxygen enrichment, significantly reducing the rate of coke consumption. If the empty charge line continues to the center line of the tuyeres, it will take a long time and involve huge risks.

[0077] In addition, maintaining a material column thickness of 2-4m above the center line of the tuyere and a greater weight than the material column from the empty material line to the center line of the tuyere is beneficial for the discharge of slag and iron from the taphole.

[0078] Furthermore, it has the following advantages:

[0079] 1. Ensure that the gas flow does not penetrate the material surface.

[0080] 2. To avoid excessive residual coke in the furnace after shutdown, which facilitates subsequent material removal. 3. Increasing the weight of the material column helps to squeeze the liquid slag and iron at the bottom, allowing it to be discharged from the taphole as much as possible. After a large number of experiments, it was found that this method removes slag and iron more cleanly, reducing the workload of subsequent hearth cleaning.

[0081] Add a layer of coke to the furnace every 20 to 30 minutes. Combined with the quantitative addition of coke to the furnace, the parameters such as hydrogen and oxygen content and temperature can be more easily controlled.

[0082] Furthermore, compared to the existing shutdown method from the empty material line to the center line of the tuyere, this embodiment terminates the shutdown process at the opportune moment when the material line enters the area between the furnace waist and the furnace belly where the risk is greatest.

[0083] Furthermore, the proper use of top coke is crucial. Excessive water injection to control the top temperature can increase hydrogen content, which in turn increases the risk of detonation. Mastering this balance requires considerable technical expertise and experience. This embodiment combines top coke with the method of controlling the top temperature, adding a means to reduce the top temperature. Top coke should be avoided as much as possible during the initial shutdown period, and a new batch of top coke should be added every 20-30 minutes as needed in the later stages. This method is easy to control, helps stabilize the water injection volume, and reduces the risk of excessive hydrogen content.

[0084] The atomizing water spraying device is installed at the throat of the blast furnace, below the gas cover. Its atomizing nozzles are arranged around the circumference of the inner wall of the blast furnace, and the number is an even number. In this embodiment, 12 nozzles are preferably installed to ensure that the water spraying range can cover the entire throat section.

[0085] Example 3

[0086] Reference Figures 1-5This is the third embodiment of the present invention. This embodiment differs from the second embodiment in that it provides an operating system for improving the safety of large blast furnace shutdown. It is applicable to the operation method for improving the safety of large blast furnace shutdown described in the above embodiments, and also includes a gas monitoring module 100 for real-time acquisition of the current concentration of hydrogen and oxygen in the blast furnace during the shutdown process.

[0087] Temperature monitoring module 200 is used to monitor the stable changes in temperature inside the blast furnace in real time during the shutdown process.

[0088] Processing module 300, which is electrically connected to the atomizing water spraying device, the blower, the gas monitoring module 100, and the temperature monitoring module 200, is used to receive and determine the P during the blast furnace shutdown process. H Is it greater than P? Y P O Is it greater than P? S And further determine T D With T S T Y and T B The size relationship is determined and the result is sent to the control center 301. The control center 301 then issues instructions to control the atomizing water spraying device to spray water and the fan to blow air.

[0089] Furthermore, during the shutdown process, the gas monitoring module 100 monitors the furnace temperature in real time and sends the measured values ​​to the processing module 300, which then determines P. H Is it greater than P? Y P O Is it greater than P? S If so, the control center 301 will issue working instructions to the atomizing water spraying device and the fan.

[0090] Furthermore, the topcoat is added manually, and the amount and frequency of addition are as described in the above embodiments.

[0091] 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. An operating method for improving the safety of large blast furnace shutdown, characterized in that: include, When the initial shutdown begins, the hydrogen and oxygen content inside the blast furnace is monitored in real time. Determine P O Is it greater than P? S P H Is it greater than P? Y , where P Y P represents the permissible hydrogen content in a blast furnace. H P represents the current hydrogen content inside the blast furnace. S P represents the permissible oxygen content in a blast furnace. O This represents the current oxygen content inside the blast furnace. At the same time, the furnace top temperature is monitored in real time; When P O Less than P S If P H Less than P Y Then determine T D Is it less than T within the preset time? S T D T represents the current temperature inside the blast furnace. S If the temperature inside the blast furnace is low, the furnace will be stopped after the charge is introduced into the furnace, and the blower will be kept at maximum airflow. If not, then determine T. D Is it greater than T within the preset time? S And less than T Y， Where T Y The highest temperature for the first-stage cooling in the blast furnace is if so. If so, increase the amount of water applied while continuing to cover the surface with coke. If not, then determine T. D Is it greater than T within the preset time? Y And less than T B T B This is the highest temperature for the secondary cooling stage inside the blast furnace. If so, reduce the airflow of the blower. When P O Less than P S If P H Greater than P Y Then determine T D Is it less than T within the preset time? S If so, turn on the atomizing water dispenser and control it to reduce the amount of water dispensed; If not, then determine T. D Is it greater than T within the preset time? S And less than T Y If so, increase the amount of water applied while continuing to cover the surface with charcoal. If not, then determine T. D Is it greater than T within the preset time? Y And less than T B If so, reduce the fan air volume and reduce the amount of water pumped; When P O Greater than P S This reduces the air volume of the fan; The maximum output air volume of the fan is 100%. In the early stage, it maintains 80% to 90% of the total air volume. When the fan air volume is reduced, it is reduced by 3% to 5% of the total air volume each time. The capping coke is a porous honeycomb structure with small particles, and its pores can absorb moisture to reach a water saturation state. The T S The value is 280℃, and the T Y The value is 350℃, and the T B The value is 500℃; The atomizing water spraying device is installed at the throat of the blast furnace, below the gas cover, and its atomizing nozzles are arranged along the circumference of the inner wall of the blast furnace in an even number.

2. The operation method for improving the shutdown safety of large blast furnaces according to claim 1, characterized in that: The P Y The value is 12% vol, P S The value is 1% vol.

3. The operation method for improving the shutdown safety of large blast furnaces according to claim 2, characterized in that: The coke used for covering the furnace is added in batches, and the formula for calculating the amount used in each batch is as follows: T=0.5πr² Where T represents the total amount of coke added in each batch, π represents pi, and r represents the radius of the furnace throat.

4. The operation method for improving the shutdown safety of large blast furnaces according to claim 3, characterized in that: When the upper material line of the empty material line reaches 2-4m above the center line of the blast furnace tuyeres, the blower stops blowing.

5. The operation method for improving the shutdown safety of large blast furnaces according to claim 4, characterized in that: Add a layer of coke to the furnace every 20 to 30 minutes.

6. An operating system for improving the safety of large blast furnace shutdowns, characterized in that: The operating method applicable to improving the shutdown safety of large blast furnaces as described in any one of claims 1 to 5 includes, The gas monitoring module (100) is used to collect the current concentration of hydrogen and oxygen in the blast furnace in real time during the shutdown process; Temperature monitoring module (200) is used to monitor the stable changes in temperature inside the blast furnace in real time during the shutdown process; The processing module (300), which is electrically connected to the atomizing water spraying device, the blower, the gas monitoring module (100), and the temperature monitoring module (200), is used to receive and determine the P during the blast furnace shutdown process. H Is it greater than P? Y P O Is it greater than P? S And further determine T D With T S T Y and T B The size relationship is determined and the result is sent to the control center (301). The control center (301) then issues an instruction to control the atomizing water spraying device to spray water and the fan to blow air.

Images