A furnace top coal gas temperature regulation method and system based on premixed combustion technology

Abstract

This invention relates to a method and system for controlling the temperature of furnace top gas based on premixed combustion technology, belonging to the field of blast furnace ironmaking technology. Addressing the problem that existing technologies cannot effectively prevent bag filter clogging due to excessively low inlet gas temperature, this invention installs a premixed combustion unit in the gas hood or riser pipe. This unit premixes and ignites the pressure-regulated combustible gas with an auxiliary combustion gas to generate high-temperature flue gas, which directly mixes and exchanges heat with the blast furnace gas. The system monitors the furnace top temperature and bag filter inlet temperature in real time, calculates future temperature values ​​based on a unique time-delay prediction model, dynamically starts and stops the combustion unit, and intelligently adjusts the number of burners in operation to ensure that the temperature remains consistently above the dew point temperature and below the bag filter's tolerance limit. Its advantages include: significantly improved temperature control reliability, complete elimination of the risk of bag clogging; compact equipment structure and convenient maintenance; avoidance of interference with normal blast furnace operation; and achievement of efficient energy utilization and inherently safe operation.

Description

Technical Field

[0001] This invention belongs to the field of blast furnace ironmaking technology, and relates to a method and system for controlling the temperature of furnace top gas based on premixed combustion technology. Background Technology

[0002] Blast furnace ironmaking is a key process in modern steel production. During blast furnace smelting, a large amount of dust-laden blast furnace gas is generated. This dust-laden blast furnace gas flows sequentially through a gas hood, outlet pipe, riser pipe, five-way ball, and downcomer pipe, entering a rough gas dust collector for preliminary dust removal to remove large particles. The gas after rough dust removal is called raw gas, which then enters a dry bag filter for fine dust removal through a raw gas pipeline to remove fine particles, finally yielding clean gas that enters the gas pipeline network for utilization.

[0003] The temperature of the gas entering the dry baghouse dust collector is crucial. This temperature mainly depends on the temperature of the gas at the furnace top and the heat exchange between the raw gas system (including the blast furnace gas hood, outlet pipe, riser pipe, downcomer pipe, raw gas dust collector, and raw gas pipeline) and the external environment. Many factors can lead to a decrease in the temperature of the gas at the furnace top: excessive pursuit of low fuel ratios and high oxygen enrichment; unreasonable gas flow distribution or charging system within the blast furnace; insufficient sensible heat of the raw materials such as sinter, excessively high proportion of magnetite, or excessive limestone usage; excessively high moisture content in the coke; high silicon and low heat during blast furnace operation, insufficient hearth activity, and incomplete indirect reduction leading to increased heat consumption in direct reduction; and the current exploration of low-carbon smelting technologies also tends to lower the furnace top temperature. The heat loss from the raw gas system to the outside is affected by ambient temperature, wind speed, pipeline insulation, and gas flow rate. Low ambient temperature, high wind speed, thin coating inside the pipe or lack of external insulation layer will all exacerbate heat loss and further reduce the temperature of the gas entering the dry bag filter.

[0004] When the temperature of the raw coal gas entering the dry baghouse dust collector is lower than its dew point temperature, the water vapor in the gas condenses into liquid water droplets. These tiny water droplets easily combine with the fine dust remaining in the gas, forming a viscous substance that adheres to the surface of the filter bags in the dry baghouse dust collector. This phenomenon is called "bag clogging." Bag clogging causes a sharp decrease in filter bag permeability, a significant increase in filtration resistance, and a substantial reduction in dust removal efficiency. If bag clogging occurs frequently or persists for a long time, it will eventually lead to filter bag blockage, seriously threatening the safe and stable operation of the dry baghouse dust collector and even the entire blast furnace system.

[0005] Currently, conventional methods such as thickening the inner wall of pipelines with spray coating or insulating the outer wall have limited effectiveness in reducing gas temperature drop. Simply increasing the coating thickness can slightly increase the heat transfer resistance, but the effect is not significant and it significantly increases the load on the pipeline structure; therefore, the coating should not be too thick. External insulation layers can more effectively improve thermal resistance, but high-altitude construction is difficult, and wrapping the pipe with insulation can obscure the pipeline itself, hindering the timely detection of potential gas leaks. It also leads to increased pipe shell temperature and thermal stress. Therefore, preventing excessive gas temperature drop by reducing heat dissipation presents significant technical challenges and limitations.

[0006] Existing technologies for increasing the inlet gas temperature of dry baghouse dust collectors mainly focus on the heating stage. A common approach is to use the exhaust gas from a hot blast stove or the high-temperature flue gas generated from the combustion of combustible gases as a heat source, indirectly heating the raw gas through a heat exchanger. However, indirect heat exchange is inefficient, resulting in a slow temperature rise; the high dust content in the raw gas easily wears down the heat exchanger, leading to a high equipment failure rate; and the huge flow rate of blast furnace gas necessitates large heat exchange equipment, resulting in high investment and significant land occupation. Another approach is to directly burn a portion of the blast furnace gas within the raw gas system to raise its temperature.

[0007] For example, patent "CN109385497A" proposes installing nozzles in the lower straight section of a gravity dust collector to inject high-pressure oxygen and ignite it, thus igniting the blast furnace gas inside the dust collector and using the heat of combustion to heat the remaining gas. However, this method has significant drawbacks: the mixing and combustion process of a large volume of high-speed oxygen with the gas is difficult to control, and deflagration or flameout is highly likely, posing safety hazards. The impact of deflagration may damage the dust collector's lining or shell; the strong disturbance generated by combustion severely affects the flow field in the flared outlet area of ​​the gravity dust collector, significantly reducing its coarse dust removal efficiency; the combustion position is too close to the inlet of the dry bag filter, making it difficult for the high-temperature flue gas and gas to mix evenly, easily leading to localized high temperatures that burn the filter bags or localized low temperatures that remain below the dew point. Patent "CN204125470U" places the burner in the blast furnace gas hood or riser pipe, which also faces the problem of difficult combustion control.

[0008] Patent "CN101818220A" involves drawing a portion of the crude gas from the crude gas pipeline to a separately installed high-pressure combustion furnace. The resulting high-temperature flue gas mixes with the drawn-out gas, is heated, and then returned to the main pipeline for further mixing. This scheme involves a complex system, huge investment, and extremely high requirements for the high-temperature, high-pressure, and insulation performance of the combustion furnace and the high-temperature flue gas conveying pipeline. The drawn-out crude gas also has a high dust content, which can easily lead to wear and tear on equipment such as the compressor and valves. Patent "CN116516087A" installs a combustion heat storage device at the furnace throat steel bricks, using high-speed jet heating technology to inject combustion flue gas into the furnace throat at extremely high speeds. This device is bulky and occupies a lot of space; the high-speed jet can interfere with the normal gas flow distribution and charge distribution trajectory within the blast furnace; the high-temperature, high-speed flue gas causes severe erosion and thermal shock to the refractory materials near the device outlet, affecting the equipment's lifespan.

[0009] In summary, existing methods for increasing the temperature of the furnace top gas to solve the problem of filter bag clogging generally suffer from drawbacks such as complex equipment, high investment, high energy consumption, low efficiency, high safety risks, impact on blast furnace operation stability or dust removal efficiency, and easy equipment damage. Therefore, there is an urgent need to develop a new furnace top gas temperature control technology that is simple in equipment, safe and reliable, flexible in control, does not affect blast furnace operation, has high heat exchange efficiency, and can effectively prevent filter bag clogging. Summary of the Invention

[0010] In view of this, the purpose of the present invention is to provide a method and system for controlling the temperature of blast furnace top gas based on premixed combustion technology, which aims to raise the temperature of blast furnace gas before entering the dry bag filter to above the dew point temperature, thereby effectively preventing the occurrence of "bag clogging".

[0011] To achieve the above objectives, the present invention provides the following technical solution:

[0012] A method for controlling the temperature of furnace top gas based on premixed combustion technology, applied in blast furnace ironmaking process, includes the following steps:

[0013] S1: Real-time monitoring of the gas temperature T1 at the top of the furnace and the gas temperature T2 before entering the dry bag filter 7;

[0014] S2: Based on the temperature value monitored by S1, calculate or predict the inlet gas temperature T of the dry bag filter at a future time. 2+t ;

[0015] S3: Determine the T obtained from S2 2+t Is it less than or equal to the preset dew point temperature T? min ;

[0016] S4: If S3 determines yes, then execute the following heating steps:

[0017] S41: Adjust the pressure of the combustible gas to the target pressure;

[0018] S42: The combustible gas and the combustion-supporting gas after pressure regulation in S41 are premixed at the front end of the burner 12 to form a premixed gas; S43: The premixed gas formed in S42 is ignited, so that it continues to burn in the burner 12 to produce high-temperature flue gas.

[0019] S44: The high-temperature flue gas generated by S43 is introduced into the blast furnace gas cover 1 or riser pipe 3 area of ​​the blast furnace gas system to directly mix and exchange heat with the blast furnace gas.

[0020] S5: During the heating process, according to the set target temperature T 2set Based on real-time temperature monitoring, the number of burners 12 put into operation is intelligently adjusted.

[0021] S6: Real-time monitoring of the combustion status of burner 12 and the oxygen content of clean gas, and execution of safety protection operations;

[0022] In S2, the inlet gas temperature T of the dry bag filter at a future time is... 2+t The calculation formula is:

[0023] T 2+t =T1-(T 1-t -T2)

[0024] Among them, T 2+t T represents the inlet gas temperature of the dry bag filter after t seconds; T1 represents the current furnace top gas temperature; T2 represents the current inlet gas temperature of the dry bag filter; T 1-t t represents the temperature of the blast furnace top gas t seconds ago; t represents the time required for the blast furnace gas to travel from the top of the furnace to the inlet of the dry bag filter.

[0025] Furthermore, in S2, time t is calculated using the following formula:

[0026]

[0027] Among them, L1, L2, L3 and L4 are the lengths of riser pipe 3, downcomer pipe 4, coarse gas dust collector 5 straight section and raw gas pipeline 6, respectively.

[0028] V1, V2, V3, and V4 are the average flow velocities of blast furnace gas in the riser pipe 3, downcomer pipe 4, the straight section of the crude gas dust collector 5, and the raw gas pipeline 6, respectively.

[0029] Furthermore, S5 specifically includes:

[0030] S51: The initial number of burner groups n (12 sets) is calculated and rounded using the following formula:

[0031]

[0032] Among them, T 2,0 This indicates the inlet gas temperature of the dry bag filter when premixed combustion is not enabled; T 2,N This indicates the maximum achievable inlet gas temperature for a dry bag filter achievable using this method; T 2set This indicates the set target inlet gas temperature for the dry bag filter; N represents the total number of groups into which burner 12 is divided.

[0033] S52: During premixed combustion operation, calculate the average inlet gas temperature T of the dry bag filter within any consecutive 2t time period. 2avr With the set target temperature T 2set The difference ΔT2 = T 2avr -T2set ;

[0034] S53: If ΔT2≤b, where b is a manually set negative deviation threshold, then an additional set of burners 12 will be automatically enabled.

[0035] S54: If ΔT2≥c, where c is a manually set positive deviation threshold, then one group of burners 12 will be automatically deactivated.

[0036] Furthermore, it also includes the following steps:

[0037] S7: During the heating process, the T obtained from S2 is judged in real time. 2+t Is it greater than or equal to the preset burn-out temperature T of the cloth bag? max S8: If S7 determines that it is yes, then shut down the premixed combustion system.

[0038] Furthermore, the burners 12 are evenly arranged in the same circumferential direction inside the blast furnace gas cover 1 or the riser pipe 3, and the number is 8 to 16, which are evenly divided into N groups. Each group of burners 12 can be controlled to start and stop independently.

[0039] Furthermore, S6 specifically includes:

[0040] S61: Real-time monitoring of the combustion status of each burner 12;

[0041] S62: When the flame of a certain group of burners 12 is detected to be extinguished, the group of burners 12 is automatically deactivated;

[0042] S63: Real-time monitoring of the oxygen content of clean coal gas;

[0043] S64: When the oxygen content of the clean coal gas is detected to be higher than the set value x, the supply of combustion-supporting gas will be automatically stopped;

[0044] S65: After the oxygen content of the clean coal gas returns to normal, reduce the flow rate of the combustion-supporting gas and restart the premixed combustion system.

[0045] A furnace top gas temperature control system based on premixed combustion technology includes:

[0046] Temperature monitoring unit: includes outlet pipe thermocouple 21 installed on outlet pipe 2 and raw gas pipeline thermocouple 61 installed on raw gas pipeline 6, which are used to detect the furnace top gas temperature T1 and the dry bag filter inlet gas temperature T2 in real time, respectively.

[0047] Temperature prediction and control unit: includes a human machine interface (HMI) and its associated electrical facilities; the signal output terminals of the outlet pipe thermocouple 21 and the raw gas pipeline thermocouple 61 are connected to the HMI; the HMI is configured to calculate or predict the inlet gas temperature T of the dry bag filter at a future time based on the detected T1 and T2 according to a preset algorithm. 2+t And according to T 2+t With the preset dew point temperature T min and the burning temperature of the cloth bag T max The comparison results, and the set target temperature T 2set Generate control commands;

[0048] Combustible gas pressure regulating and conveying unit: includes a combustible gas pressure regulating device 10 and a combustible gas conveying pipeline 11, used to regulate the pressure of combustible gas to the target pressure and convey it;

[0049] The premixed combustion unit includes multiple burners 12, combustion-supporting gas delivery pipes 9, and igniters 15. The burners 12 are evenly arranged in the same circumferential direction within the blast furnace gas shroud 1 or the riser pipe 3. Their inlets are connected to the combustible gas delivery pipe 11 and the combustion-supporting gas delivery pipe 9 via pipelines, respectively, for premixing the pressure-regulated combustible gas and the combustion-supporting gas at the front end of the burners. The igniter 15 is located inside or near the burners 12 and is used to ignite the premixed gas to generate high-temperature flue gas. The high-temperature flue gas and blast furnace gas are directly mixed and exchanged for heat within the blast furnace gas shroud 1 or the riser pipe 3. The start and stop of the premixed combustion unit are controlled by control commands generated by the temperature prediction and control unit.

[0050] Safety monitoring and protection unit: includes a flame detector 13 and a plasma flame probe 14 for monitoring the combustion status of burner 12, and a gas composition analyzer 81 for monitoring the oxygen content of clean gas; the flame detector 13 and the plasma flame probe 14 are located at the outlet or inside of burner 12, and the gas composition analyzer 81 is located on clean gas pipeline 8; the signal output terminals of the flame detector 13, the plasma flame probe 14, and the gas composition analyzer 81 are connected to the temperature prediction and control unit or the direct interlock control device;

[0051] The temperature prediction and control unit is further configured to: predict the target temperature T based on the set target temperature T. 2set The inlet gas temperature T of the dry bag filter when the premixed combustion unit is not in use 2,0 and the maximum temperature T that the system design can achieve. 2,N Calculate the initial number of burner groups; during the operation of the premixed combustion unit, based on the average inlet gas temperature T of the dry bag filter over a continuous time period. 2avr With T 2setThe difference ΔT2 automatically adjusts the number of burner groups put into operation; and when the safety monitoring and protection unit receives a flame extinguishing signal or a signal indicating that the oxygen content of the clean gas exceeds the standard, it performs the corresponding safety protection operation.

[0052] Furthermore, the safety monitoring and protection unit also includes an infrared thermal imager 16, which is installed above the blast furnace gas cover 1 and its signal output terminal is connected to the temperature prediction and control unit or the operating station to observe the combustion status of all burners 12.

[0053] Furthermore, the number of burners 12 is 8 to 16, and they are evenly divided into N groups; each group of burners 12 is equipped with an independent combustible gas supply valve, an auxiliary combustion gas supply valve and an igniter 15, and is individually controlled to start and stop by the temperature prediction and control unit.

[0054] Furthermore, the temperature monitoring unit also includes an outlet pipe pressure transmitter 22 installed on the outlet pipe 2 and a raw gas pipeline pressure transmitter 62 installed on the raw gas pipeline 6, for monitoring the gas pressure; the combustible gas is natural gas, coke oven gas, converter gas or blast furnace clean gas; the combustion-supporting gas is oxygen or compressed air.

[0055] The beneficial effects of this invention are as follows:

[0056] (1) Significant and reliable temperature boost, intelligent and precise temperature control

[0057] By adopting a method of direct mixing and heat exchange between premixed combustion flue gas and blast furnace gas, the bottleneck of low efficiency in traditional indirect heat exchange is overcome, and the gas temperature is rapidly and stably increased.

[0058] By accurately predicting the future inlet temperature of the dry bag filter, a dual protection threshold based on dew point temperature and bag tolerance temperature is established. This dynamically responds to changes in operating conditions and triggers a temperature intervention mechanism in advance, fundamentally eliminating the phenomenon of bag clogging.

[0059] The burner group control strategy automatically matches the initial number of burners to the target temperature and automatically increases or decreases the number of operating groups based on real-time temperature differences. The closed-loop control system continuously maintains the target temperature range, adapts to changes in blast furnace conditions, and effectively reduces energy waste.

[0060] (2) Optimize system structure and operation and maintenance costs

[0061] The core equipment is integrated into the existing blast furnace gas cover or riser pipe area, making full use of the furnace top platform space and avoiding additional land occupation.

[0062] The modular design makes the burner assembly easy to install and maintain, while each burner assembly can serve as a backup for the others.

[0063] Compared to independent combustion furnaces or heat exchanger solutions, it significantly reduces the investment in high-temperature and high-pressure pipelines and large equipment.

[0064] (3) Ensure stable blast furnace production and safe system operation.

[0065] By premixing and burning multiple small-volume burners, the flame range is small, the combustion is stable and controllable, and the flue gas release rate is matched with the mainstream gas flow, so that the high-temperature flue gas flow has almost no impact on the gas flow distribution, material distribution trajectory and refractory material.

[0066] Premixed combustion technology avoids the risk of deflagration at the source. Combined with multiple flame monitoring devices such as flame detectors, plasma flame probes, and infrared thermal imagers, it automatically cuts off the burner when flameout occurs, ensuring the safe operation of the system in real time.

[0067] The oxygen content interlock protection mechanism promptly cuts off abnormal operating conditions to prevent the oxygen content in the gas system from exceeding the standard.

[0068] (4) Improve environmental protection operation efficiency

[0069] Completely eliminate the problem of dust caking caused by low temperature and ensure long-term stable efficiency of bag filter dust collection.

[0070] Extend the service life of filter bags and reduce the frequency of unplanned downtime.

[0071] The design minimizes combustible gas consumption to maintain the stable calorific value of net coal gas and does not affect subsequent energy recovery and utilization.

[0072] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0073] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0074] Figure 1 This is a schematic diagram of the system of the present invention;

[0075] Figure 2 This is a magnified view of a portion of the blast furnace gas sealing area.

[0076] Figure reference numerals: 1. Blast furnace gas hood; 2. Outlet pipe; 3. Ascending pipe; 4. Downlet pipe; 5. Raw gas dust collector; 6. Raw gas pipeline; 7. Dry bag filter; 8. Clean gas pipeline; 21. Outlet pipe thermocouple; 22. Outlet pipe pressure transmitter; 61. Raw gas pipeline thermocouple; 62. Raw gas pipeline pressure transmitter; 81. Gas composition analyzer; 9. Combustible gas conveying pipeline; 10. Combustible gas pressure regulating device; 11. Combustible gas conveying pipeline; 12. Burner; 13. Flame detector; 14. Plasma flame probe; 15. Ignition device; 16. Infrared thermal imager. Detailed Implementation

[0077] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0078] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0079] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0080] Please see Figure 1 and Figure 2This invention is based on premixed combustion direct heat exchange and intelligent predictive control technology. By injecting a small amount of high-temperature flue gas into the gas hood or riser area, it achieves precise control of the gas temperature at the furnace top. The system monitors the temperature at key points in real time and uses a unique time-delay temperature prediction model to predict the future temperature at the bag filter inlet. It dynamically starts and stops the premixed combustion device and intelligently adjusts the combustion intensity to ensure that the gas temperature is always higher than the dew point temperature and lower than the filter bag's tolerance limit, fundamentally eliminating the risk of filter bag clogging.

[0081] Example 1: Using 2000m 3 Taking a blast furnace as an example

[0082] In this embodiment, blast furnace gas enters the outlet pipe 2 through the blast furnace gas cover 1, then enters the crude gas dust collector 5 for coarse dust removal through the riser pipe 3 and the downcomer pipe 4, then enters the dry bag filter 7 for fine dust removal through the raw gas pipeline 6, and finally enters the gas pipeline network through the clean gas pipeline 8.

[0083] In this embodiment, the gas generation rate is 500,000 Nm³. 3 / h, the pressure of the gas at the top of the furnace, measured by the pressure transmitter 22 of the four outlet pipes, is 0.25 MPa, and the temperature of the gas at the top of the furnace, measured by the thermocouple 21 of the four outlet pipes, is T. 1,0 =130℃. The temperature of the gas entering the dry bag filter is T, measured by thermocouple 61 in the raw gas pipeline. 2,0 =100℃, after direct heat exchange with premixed combustible gas flue gas, the maximum temperature that can be reached is T. 2,N =120℃, the gas pressure measured by the raw gas pipeline pressure transmitter 62 is slightly less than 0.25MPa.

[0084] In this embodiment, the combustible gas is supplied by the combustible gas delivery pipeline 11 and its pressure is adjusted to 0.28 MPa by the combustible gas pressure regulating device 10. The auxiliary combustion gas is supplied by the auxiliary combustion gas delivery pipeline 9. Eight burners 12 are installed inside the blast furnace gas shroud 1, spaced apart from the top water spray gun. The combustible gas and the auxiliary combustion gas are premixed at the front end of the burner 12, ignited by the igniter 15, and fully combusted in the burner 12. The resulting high-temperature flue gas enters the upper part of the blast furnace gas shroud 1 and directly exchanges heat with the blast furnace gas to increase the temperature of the top gas.

[0085] In this embodiment, at any given time, the iteratively calculated value T of the gas temperature at the inlet of the dry bag filter is... 2+t When the temperature is ≤100℃, premixed combustion of combustible gas shall be activated. 2+t When the temperature is ≥150℃, turn off the premixed combustion of combustible gas.

[0086] In this embodiment, the 8 burners are divided into 4 groups. The inlet temperature of the dry bag filter is set at 110℃. Initially, 2 groups of burners are put into use. During use, when ΔT2≤-5℃, an additional group of burners is activated. When ΔT2≥5℃, one group of burners is deactivated.

[0087] In this embodiment, the combustion status of all burners 12 can be manually identified by an infrared thermal imager 16 installed above the blast furnace gas cover. When the flame of a certain burner is observed to be extinguished, that burner can be manually shut down. At the same time, the combustion status of the burner 12 outlet and inside can be automatically identified by the flame detection device 13 and the plasma flame probe 14. When the flame is detected to be extinguished, the group of burners is automatically shut down.

[0088] In this embodiment, a gas composition analyzer 81 is installed on the clean gas pipeline 8 to analyze the composition of the clean gas and determine the oxygen content of the clean gas. When the oxygen content of the clean gas exceeds 1%, the supply of combustion-supporting gas is automatically stopped. After the oxygen content returns to normal, the flow rate of the combustion-supporting gas is reduced and the premixed combustion system is restarted.

[0089] The main technical and economic indicators of this embodiment are detailed in Table 1.

[0090] Table 1 Main Technical and Economic Indicators of the Embodiments

[0091]

[0092] Example 2: Rapid Switching of Coke Oven Gas Backup System

[0093] Emergency situation: Natural gas supply interruption;

[0094] Backup gas source: coke oven gas;

[0095] Burner grouping: 4 independent gas supply systems;

[0096] Emergency Response Procedures

[0097] 1. Gas source switching

[0098] The safety system detected a failure in the natural gas pipeline pressure reducing valve;

[0099] Shut down the oxygen and natural gas lines;

[0100] Automatically activate the coke oven gas pressurization device;

[0101] Open the coke oven gas pipeline and oxygen pipeline.

[0102] 2. Reset combustion parameters

[0103] The calorific value of coke oven gas is updated in the control system;

[0104] The number of burners to be used is recalculated to compensate for the difference in calorific value.

[0105] 3. Flame stabilization protection

[0106] The oxygen flow rate is reduced slightly proportionally to maintain the optimal air-fuel ratio;

[0107] Plasma flame probes were used to verify flame stability group by group.

[0108] 4. Temperature recovery

[0109] T2 returns to the set temperature, with a fluctuation range of -3℃ to 3℃;

[0110] 5. Technological advantages

[0111] No manual intervention is required throughout the entire gas source switching process;

[0112] The time for temperature runaway has been reduced to less than 6 minutes;

[0113] Multiple combustion monitoring systems eliminate the risk of flameout.

[0114] Finally, 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 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 the temperature of furnace top gas based on premixed combustion technology, applied in blast furnace ironmaking process, characterized in that: Includes the following steps: S1: Real-time monitoring of gas temperature at the furnace top and the temperature of the gas before entering the dry bag filter (7) ; S2: Based on the temperature value monitored by S1, calculate or predict the inlet gas temperature of the dry bag filter at a future time. ; S3: Determine the result obtained from S2 Is it less than or equal to the preset dew point temperature? ; S4: If S3 determines yes, then execute the following heating steps: S41: Adjust the pressure of the combustible gas to the target pressure; S42: The combustible gas and the combustion-supporting gas after pressure regulation in S41 are premixed at the front end of the burner (12) to form a premixed gas; S43: The premixed gas formed in S42 is ignited and it continues to burn in the burner (12) to produce high-temperature flue gas; S44: The high-temperature flue gas generated by S43 is introduced into the blast furnace gas cover (1) or riser pipe (3) area of ​​the blast furnace gas system and directly mixed and exchanged heat with the blast furnace gas. S5: During the heating process, according to the set target temperature Based on real-time temperature monitoring, the number of burners (12) put into operation is intelligently adjusted; S6: Real-time monitoring of the combustion status of the burner (12) and the oxygen content of the clean gas, and execution of safety protection operations; In S2, the inlet gas temperature of the dry bag filter at a future time is... The calculation formula is: in, express The inlet gas temperature of the dry bag filter dust collector after seconds; This indicates the current temperature of the gas at the top of the furnace; This indicates the current inlet gas temperature of the dry bag filter. express The temperature of the gas at the top of the furnace seconds ago; This indicates the time required for blast furnace gas to travel from the top of the furnace to the inlet of the dry bag filter.

2. The method for controlling the temperature of furnace top gas based on premixed combustion technology according to claim 1, characterized in that: In S2, time Calculated using the following formula: in, , , and The lengths are respectively: the riser pipe (3), the downcomer pipe (4), the straight section of the coarse gas dust collector (5), and the raw gas pipeline (6); , , and The average flow velocities of blast furnace gas in the riser pipe (3), downcomer pipe (4), the straight section of the crude gas dust collector (5), and the raw gas pipeline (6) are respectively.

3. The method for controlling the temperature of furnace top gas based on premixed combustion technology according to claim 1, characterized in that: S5 specifically includes: S51: Number of burner groups (12) initially added Calculate and round using the following formula: in, This indicates the inlet gas temperature of the dry bag filter when premixed combustion is not enabled. This indicates the maximum inlet gas temperature of a dry bag filter that can be achieved using this method. This indicates the set target inlet gas temperature for the dry bag filter. N This indicates the total number of groups into which the burner (12) is divided; S52: During premixed combustion operation, in any continuous Calculate the average inlet gas temperature of the dry bag filter during the specified time period. With the set target temperature The difference ; S53: If , If a negative deviation threshold is set manually, a set of burners will be automatically added (12). S54: If , If a positive deviation threshold is set manually, a group of burners will be automatically deactivated (12).

4. The method for controlling the temperature of furnace top gas based on premixed combustion technology according to claim 1, characterized in that: It also includes the following steps: S7: During the heating process, the value obtained from S2 is judged in real time. Is it greater than or equal to the preset burn temperature of the cloth bag? S8: If S7 determines that it is yes, then shut down the premixed combustion system.

5. The method for controlling the temperature of furnace top gas based on premixed combustion technology according to claim 1, 3, or 4, characterized in that: The burners (12) are evenly arranged inside the blast furnace gas shroud (1) or on the same circumferential direction of the riser pipe (3), and the number is 8 to 16, and they are evenly divided into N Each group of burners (12) can be individually controlled to start and stop.

6. The method for controlling the temperature of furnace top gas based on premixed combustion technology according to claim 1, characterized in that: S6 specifically includes: S61: Real-time monitoring of the combustion status of each burner (12); S62: When the flame of a certain group of burners (12) is detected to be extinguished, the group of burners (12) is automatically deactivated. S63: Real-time monitoring of the oxygen content of clean coal gas; S64: When the oxygen content of the clean coal gas is detected to be higher than the set value. x When this happens, the supply of combustion-supporting gas will automatically stop; S65: After the oxygen content of the clean coal gas returns to normal, reduce the flow rate of the combustion-supporting gas and restart the premixed combustion system.

7. A furnace top gas temperature control system based on premixed combustion technology, characterized in that: include: Temperature monitoring unit: includes a thermocouple (21) installed on the outlet pipe (2) and a thermocouple (61) installed on the raw gas pipeline (6), which are used to detect the temperature of the gas at the top of the furnace in real time. and the temperature of the gas before entering the dry bag filter ; Temperature prediction and control unit: including human-machine interface (HMI) and its associated electrical facilities; the signal output terminals of the outlet pipe thermocouple (21) and the raw coal gas pipeline thermocouple (61) are connected to the HMI; the HMI is configured to predict and control the temperature based on the detected temperature according to a preset algorithm. and Calculate or predict the inlet gas temperature of a dry bag filter at a future time. and according to With the preset dew point temperature and the temperature at which the cloth bag burns The comparison results, and the set target inlet gas temperature of the dry bag filter. Generate control commands; Combustible gas pressure regulating and conveying unit: includes a combustible gas pressure regulating device (10) and a combustible gas conveying pipeline (11), used to regulate the pressure of combustible gas to the target pressure and convey it; The premixed combustion unit includes multiple burners (12), combustion gas delivery pipes (9), and igniters (15). The burners (12) are evenly arranged in the same circumferential direction inside the blast furnace gas hood (1) or the riser pipe (3). Their inlets are connected to the combustible gas delivery pipe (11) and the combustion gas delivery pipe (9) through pipelines, respectively, for premixing the pressure-regulated combustible gas and the combustion gas at the front end of the burner. The igniter (15) is located inside or near the burner (12) for igniting the premixed gas to generate high-temperature flue gas. The high-temperature flue gas and the blast furnace gas are directly mixed and exchanged for heat in the blast furnace gas hood (1) or the riser pipe (3). The start and stop of the premixed combustion unit are controlled by the control commands generated by the temperature prediction and control unit. Safety monitoring and protection unit: includes a flame detector (13) and a plasma flame probe (14) for monitoring the combustion status of the burner (12), and a gas composition analyzer (81) for monitoring the oxygen content of the clean gas; the flame detector (13) and the plasma flame probe (14) are located at the outlet or inside of the burner (12), and the gas composition analyzer (81) is located on the clean gas pipeline (8); the signal output terminals of the flame detector (13), the plasma flame probe (14) and the gas composition analyzer (81) are connected to the temperature prediction and control unit or the direct interlock control device; The temperature prediction and control unit is further configured to: predict the target temperature. Inlet gas temperature of dry bag filter without premixed combustion unit and the maximum inlet gas temperature achievable by the system design for a dry bag filter. Calculate the initial number of burner groups; during the operation of the premixed combustion unit, calculate the average inlet gas temperature of the dry bag filter over a continuous time period. and The difference It automatically increases or decreases the number of burner groups in operation; and when it receives a flame extinguishing signal or a signal indicating that the oxygen content of the clean gas exceeds the standard from the safety monitoring and protection unit, it performs corresponding safety protection operations.

8. The furnace top gas temperature control system based on premixed combustion technology according to claim 7, characterized in that: The safety monitoring and protection unit also includes an infrared thermal imager (16), which is set above the blast furnace gas cover (1) and its signal output terminal is connected to the temperature prediction and control unit or the operating station to observe the combustion status of all burners (12).

9. The furnace top gas temperature control system based on premixed combustion technology according to claim 7 or 8, characterized in that: The number of burners (12) is 8 to 16, and they are evenly divided into N Each group of burners (12) is equipped with an independent combustible gas supply valve, an auxiliary combustion gas supply valve and an igniter (15), and is individually controlled to start and stop by the temperature prediction and control unit.

10. The furnace top gas temperature control system based on premixed combustion technology according to claim 7, characterized in that: The temperature monitoring unit also includes an outlet pipe pressure transmitter (22) installed on the outlet pipe (2) and a raw gas pipeline pressure transmitter (62) installed on the raw gas pipeline (6), for monitoring gas pressure; the combustible gas is natural gas, coke oven gas, converter gas or blast furnace clean gas; the combustion-supporting gas is oxygen or compressed air.

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