Furnace top gas temperature regulation and control method and system based on premixed combustion technology

Abstract

The invention relates to a furnace top gas temperature regulation and control method and system based on a premixed combustion technology, and belongs to the technical field of blast furnace ironmaking. Aiming at the problem that a cloth bag is burnt due to the fact that the temperature of coal gas at an inlet of a bag-type dust collector is too low cannot be effectively prevented in the prior art, a premixed combustion unit is arranged on a coal gas sealing cover or an ascending pipe, combustible gas after pressure regulation and combustion-supporting gas are premixed and ignited to generate high-temperature flue gas, and the high-temperature flue gas is directly mixed with blast furnace coal gas for heat exchange. The system monitors the furnace top temperature and the cloth bag inlet temperature in real time, calculates a future temperature value based on an original time delay prediction model, dynamically starts and stops a combustion unit, intelligently adjusts the use number of burners, and ensures that the temperature is continuously higher than the dew point temperature and lower than the cloth bag tolerance limit. The device has the beneficial effects that the temperature control reliability is obviously improved, and the risk of pasting a cloth bag is thoroughly eliminated; the equipment is compact in structure and convenient to maintain; interference on normal operation of the blast furnace is avoided; and efficient energy utilization and intrinsically safe operation are realized.

Description

Technical Field

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

[0002] Blast furnace ironmaking is a key process in modern steel production. During the blast furnace smelting process, large quantities of dusty blast furnace gas are generated. This dusty blast furnace gas flows through the gas enclosure, outlet pipe, riser, five-way ball, and downcomer, entering the crude gas dust collector for preliminary dust removal to remove large particles. This crudely cleaned gas, known as raw gas, then flows through the raw gas pipeline into a dry bag filter for fine dust removal, ultimately removing fine particles. The resulting clean gas is then fed into the gas network for utilization.

[0003] The gas temperature entering the dry bag filter is crucial. This temperature is primarily determined by the top gas temperature and the heat exchange between the raw gas system (including the blast furnace gas enclosure, outlet pipe, riser, downcomer, raw gas collector, and raw gas pipeline) and the external environment. Numerous factors can contribute to lower top gas temperature: excessive pursuit of low fuel ratios and high oxygen enrichment; inappropriate gas flow distribution or charging systems within the blast furnace; insufficient sensible heat of incoming raw materials such as sintered ore, excessive magnetite content, or excessive limestone usage; excessive coke moisture content; high silicon and low heat during blast furnace operation, insufficient hearth activity, and insufficient indirect reduction, leading to increased heat consumption in direct reduction; and currently explored low-carbon smelting technologies, which also tend to lower top temperature. Heat loss from the raw gas system to the outside world is influenced by ambient temperature, wind speed, pipeline insulation, and gas flow rate. Low ambient temperature, high wind speed, thin spray coating inside the pipeline or lack of external insulation layer will aggravate heat loss and further reduce the temperature of the gas entering the dry bag dust collector.

[0004] When the temperature of the raw gas entering a dry bag filter falls below its dew point, 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 sticky substance that adheres to the surface of the dry bag filter. This phenomenon is known as "bag sticking." Bag sticking can cause a sharp decrease in bag permeability, significantly increase filtration resistance, and significantly reduce dust removal efficiency. If bag sticking 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 bag filter and even the entire blast furnace system.

[0005] At present, conventional spraying to thicken the inner wall of the pipeline or insulating the outer wall has limited effect on reducing the temperature drop of the coal gas. Although simply increasing the spray thickness can slightly increase the heat transfer thermal resistance, the effect is not obvious, and it will significantly increase the structural load of the pipeline, so the spray should not be too thick. The outer insulation layer can more effectively improve the thermal resistance, but it is difficult to construct at high altitudes. The wrapped insulation layer will cover the pipeline body, which is not conducive to timely detection of gas leakage hazards. At the same time, it will cause the shell and tube temperature to rise and thermal stress to increase. Therefore, preventing excessive temperature drop of the coal gas by reducing heat dissipation has great technical difficulties and limitations.

[0006] Existing methods for increasing the inlet gas temperature of dry bag filters primarily focus on the heating stage. A common approach is to use hot blast furnace exhaust or high-temperature flue gas generated by burning combustible gases separately as a heat source, indirectly heating the raw gas through a heat exchanger. However, indirect heat exchange is inefficient, resulting in slow temperature rise. The high dust content of raw gas can easily wear out the heat exchanger, leading to a high rate of equipment failure. The high flow rate of blast furnace gas requires large heat exchange equipment, resulting in high investment and space requirements. Another approach is to directly burn some blast furnace gas within the raw gas system to increase the temperature.

[0007] For example, the patent "CN109385497A" proposes setting a nozzle in the lower straight section of the gravity dust collector to inject high-pressure oxygen and ignite it, igniting the blast furnace gas inside the gravity dust collector, and using the combustion heat to heat the remaining gas. However, this method has significant defects: the combustion process of a large amount of high-speed oxygen flow mixed with the gas is difficult to control, and it is very easy to cause deflagration or flameout, posing a safety hazard. The impact of the deflagration may damage the lining or shell of the dust collector; the strong disturbance generated by the combustion seriously affects the flow field in the bell-mouth outlet area of ​​the gravity dust collector, greatly reducing its coarse dust removal efficiency; the combustion position is too close to the inlet of the dry bag dust collector, and the high-temperature flue gas and the gas are difficult to mix evenly, which can easily form local high temperatures that burn the filter bags or local low temperatures that are still below the dew point. The patent "CN204125470U" sets the burner in the blast furnace gas cover or riser, and also faces the problem of difficult combustion control.

[0008] Patent "CN101818220A" draws part of the coal gas from the crude gas pipeline to a separately installed high-pressure combustion furnace for combustion. The generated high-temperature flue gas is mixed with the drawn-out coal gas and heated before being sent back to the main pipeline for mixing. This solution has a complex equipment system and huge investment. It places extremely high demands on the high-temperature resistance, high-pressure resistance, and thermal insulation performance of the combustion furnace and the high-temperature flue gas transmission pipeline. The drawn-out crude coal gas contains a large amount of dust, which can easily cause wear and failure of equipment such as compressors and valves. Patent "CN116516087A" installs a combustion heat storage device at the furnace throat steel bricks, and uses high-speed jet heating technology to spray the combustion flue gas into the furnace throat at an extremely high speed. The device is large in size and takes up a lot of space. The high-speed jet will interfere with the normal coal gas flow distribution and charge distribution trajectory in the blast furnace. The high-temperature and high-speed flue gas causes severe scouring and thermal shock to the refractory materials near the outlet of the device, affecting the life of the equipment.

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

[0010] In view of this, the purpose of the present invention is to provide a furnace top gas temperature control method and system based on premixed combustion technology, which is intended to increase the blast furnace gas temperature before entering the dry bag dust collector to above the dew point temperature, thereby effectively preventing the occurrence of the "bag sticking" phenomenon.

[0011] In order to achieve the above object, the present invention provides the following technical solutions:

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

[0013] S1: Real-time monitoring of the gas temperature T1 at the furnace top 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 T obtained in S2 2+t Is it less than or equal to the preset dew point temperature T min ;

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

[0017] S41: regulating the combustible gas pressure to a target pressure;

[0018] S42: premixing the combustible gas pressure-regulated in S41 with the combustion-supporting gas at the front end of the burner 12 to form a premixed gas; S43: igniting the premixed gas formed in S42 to cause it to continuously burn in the burner 12 to generate high-temperature flue gas;

[0019] S44: The high-temperature flue gas generated in S43 is introduced into the blast furnace gas enclosure 1 or the riser 3 area of ​​the blast furnace gas system to directly mix with the blast furnace gas for heat exchange;

[0020] S5: During the heating process, according to the set target temperature T 2set And the real-time monitoring temperature, intelligently adjust the number of burners 12 put into operation;

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

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

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

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

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

[0026]

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

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

[0029] Furthermore, the S5 specifically includes:

[0030] S51: The number of burner groups n initially put into use is calculated and rounded using the following formula:

[0031]

[0032] Among them, T 2,0 Indicates the inlet gas temperature of the dry bag filter when premixed combustion is not enabled; T 2,N It represents the maximum gas temperature at the inlet of the dry bag filter that can be achieved by this design method; T 2set Indicates the set target dry bag filter inlet gas temperature; N indicates the total number of groups into which the burner 12 is divided;

[0033] S52: During the premixed combustion operation, calculate the average dry bag filter inlet gas temperature T in any continuous 2t period of time. 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, a group of burners 12 is automatically enabled;

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

[0036] Furthermore, the method further comprises the steps of:

[0037] S7: During the heating process, the T obtained in S2 is judged in real time. 2+t Is it greater than or equal to the preset bag burnout temperature T? max ; S8: If S7 is judged to be yes, then turn off the premixed combustion system.

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

[0039] Furthermore, the S6 specifically includes:

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

[0041] S62: When it is detected that the flame of a group of burners 12 is extinguished, the burners 12 of the group are automatically deactivated;

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

[0043] S64: When it is detected that the oxygen content of the clean coal gas is higher than the set value x, the combustion-supporting gas supply is 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 reopen the premixed combustion system.

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

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

[0047] Temperature prediction and control unit: including a human machine interface (HMI) and its auxiliary electrical facilities; the signal output ends 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 dry bag filter inlet gas temperature T 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 bag burnout temperature T max The comparison results and the set target temperature T 2set , generate control instructions;

[0048] Combustible gas pressure regulating and delivery unit: includes a combustible gas pressure regulating device 10 and a combustible gas delivery pipeline 11, and is used to regulate the combustible gas pressure to a target pressure and deliver the combustible gas;

[0049] Premixed combustion unit: comprises a plurality of burners 12, a combustion-supporting gas delivery pipe 9 and an igniter 15; the burners 12 are evenly arranged in the blast furnace gas enclosure 1 or in the same circumferential direction of the riser 3, and their inlets are respectively connected to the combustible gas delivery pipe 11 and the combustion-supporting gas delivery pipe 9 through pipelines, so as to premix the pressure-regulated combustible gas and the combustion-supporting gas at the front end of the burner; the igniter 15 is arranged inside or near the burner 12, and is used to ignite the premixed gas to generate high-temperature flue gas, and the high-temperature flue gas and blast furnace gas are directly mixed and heat-exchanged in the blast furnace gas enclosure 1 or the riser 3; the start and stop of the premixed combustion unit are controlled by the control instructions generated by the temperature prediction and control unit;

[0050] Safety monitoring and protection unit: includes a flame detection device 13 and a plasma flame probe 14 for monitoring the combustion state of the burner 12, and a gas composition analyzer 81 for monitoring the oxygen content of the clean coal gas; the flame detection device 13 and the plasma flame probe 14 are arranged at the outlet or inside the burner 12, and the gas composition analyzer 81 is arranged on the clean coal gas pipeline 8; the signal output ends of the flame detection device 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] Wherein, the temperature prediction and control unit is further configured to: according to the set target temperature T 2set , Dry bag filter inlet gas temperature T when premixed combustion unit is not enabled 2,0 And the maximum temperature T that the system can achieve 2,N , calculate the number of burner groups initially put into operation; during the operation of the premixed combustion unit, according to the average dry bag filter inlet gas temperature T in a continuous time period 2avr With T 2setand when receiving a flame outage signal or a clean gas oxygen content exceeding standard signal sent by the safety monitoring and protection unit, executing a corresponding safety protection operation.

[0052] Furthermore, the safety monitoring and protection unit also includes an infrared thermal imager 16, which is arranged above the blast furnace gas enclosure 1, and its signal output end is connected to the temperature prediction and control unit or operation station for observing the combustion status of all burners 12.

[0053] Furthermore, the number of the 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, combustion-supporting gas supply valve and igniter 15, and is independently 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 arranged on the outlet pipe 2 and a raw gas pipeline pressure transmitter 62 arranged on the raw gas pipeline 6, which are used to monitor 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 the present invention are:

[0056] (1) The temperature increase is significant and reliable, and the temperature control is intelligent and precise

[0057] The method of direct mixing and heat exchange of premixed combustion flue gas and blast furnace gas is adopted to break through the bottleneck of low efficiency of traditional indirect heat exchange and achieve a rapid and stable increase in gas temperature.

[0058] By accurately predicting the future temperature value at the inlet of the dry bag dust collector, establishing a dual protection threshold based on the dew point temperature and the bag tolerance temperature, dynamically responding to changes in working conditions, triggering the temperature intervention mechanism in advance, and fundamentally eliminating the bag sticking phenomenon.

[0059] The burner grouping control strategy automatically matches the initial number of burners in operation based on the target temperature and automatically increases or decreases the number of operating groups based on the real-time temperature difference. The closed-loop control system continuously maintains the target temperature range and adapts to changes in blast furnace conditions, effectively reducing 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 area of ​​the blast furnace, making full use of the furnace top platform space and avoiding additional occupation of space.

[0062] The modular design makes the burner group easy to install and maintain, and each burner group serves as a backup for each other.

[0063] Compared with independent combustion furnace or heat exchanger solutions, it greatly 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 evenly distributing multiple groups of small-volume burners for premixed combustion, the flame range is small, the combustion is stable and controllable, and the flue gas release rate matches the mainstream gas, so that the high-temperature flue gas flow has almost no effect on the gas flow distribution, material distribution trajectory and refractory materials.

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

[0067] The oxygen content interlock protection mechanism cuts off abnormal operating conditions in time 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 compaction caused by low temperature and ensure the long-term stability of bag dust removal efficiency.

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

[0071] The design of trace combustible gas consumption keeps the calorific value of clean gas stable to the maximum extent without affecting subsequent energy recovery and utilization.

[0072] Other advantages, objects, and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art upon examination of the following description or may be learned from practice of the present invention. The objects and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings, in which:

[0074] Figure 1 A schematic diagram of the system of the present invention;

[0075] Figure 2 This is a partial enlarged view of the blast furnace gas enclosure area.

[0076] Figure numerals: blast furnace gas enclosure 1, outlet pipe 2, riser 3, downcomer 4, crude gas dust collector 5, raw gas pipeline 6, dry bag dust collector 7, clean gas pipeline 8, outlet pipe thermocouple 21, outlet pipe pressure transmitter 22, raw gas pipeline, raw gas pipeline thermocouple 61, raw gas pipeline pressure transmitter 62, gas composition analyzer 81, combustion-supporting gas delivery pipeline 9, combustible gas pressure regulating device 10, combustible gas delivery pipeline 11, burner 12, fire detection device 13, plasma flame probe 14, igniter 15, infrared thermal imager 16. DETAILED DESCRIPTION

[0077] The following describes the embodiments of the present invention by means of specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways 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 illustrations of the basic concept of the present invention, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0078] Among them, the accompanying drawings are only for illustrative purposes and represent only schematic diagrams rather than actual pictures, and should not be understood as limiting the present invention. In order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the dimensions of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions may be omitted in the accompanying drawings.

[0079] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "back", etc. indicating directions or positional relationships, they are based on the directions or positional relationships 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 direction, be constructed and operate in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0080] See also Figure 1 and Figure 2This invention, based on direct heat exchange with premixed combustion and intelligent predictive control technology, precisely controls the gas temperature at the furnace top by injecting a small amount of high-temperature flue gas into the gas enclosure or riser. The system monitors key temperatures in real time and uses a unique time-delay temperature prediction model to predict the future bag filter inlet temperature. It dynamically starts and stops the premixed combustion device and intelligently adjusts combustion intensity to ensure that the gas temperature remains above the dew point and below the bag filter tolerance limit, fundamentally eliminating the risk of bag sticking.

[0081] Example 1: 2000m 3 Grade blast furnace as an example

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

[0083] In this embodiment, the gas generation volume is 500000Nm 3 / h, the furnace top gas pressure is measured by the four outlet pipe pressure transmitters 22 as 0.25MPa, and the furnace top gas temperature is measured by the four outlet pipe thermocouples 21 as T 1,0 =130℃. The gas temperature before entering the dry bag filter is measured by the raw gas pipeline thermocouple 61 as T 2,0 = 100℃, after direct heat exchange with flue gas through premixed combustion of combustible gas, the maximum temperature that can be reached is T 2,N =120°C, the gas pressure is measured by the raw gas pipeline pressure transmitter 62 and is slightly less than 0.25 MPa.

[0084] In this embodiment, combustible gas is supplied by a combustible gas delivery pipeline 11 and pressure-regulated to 0.28 MPa by a combustible gas pressure regulating device 10. Supporting gas is supplied by a combustion-supporting gas delivery pipeline 9. Eight burners 12 are installed within the blast furnace gas enclosure 1, spaced apart from the top sprinkler lances. Combustible gas and supporting gas are premixed at the front ends of the burners 12, ignited by igniters 15, and fully combusted within the burners 12. The resulting high-temperature flue gas enters the upper portion of the blast furnace gas enclosure 1, where it directly exchanges heat with the blast furnace gas, raising the top gas temperature.

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

[0086] In this embodiment, 8 burners are divided into 4 groups, the inlet temperature of the dry bag dust collector is set at 110°C, and 2 groups of burners are initially put into use. During use, when ΔT2≤-5°C, one group of burners is added and enabled, and when ΔT2≥5°C, one group of burners is disabled.

[0087] In this embodiment, an infrared thermal imager 16 installed above the blast furnace gas enclosure allows manual identification of the combustion status of all burners 12. If a burner's flame is observed to be extinguished, that burner can be manually deactivated. Simultaneously, a flame detection device 13 and a plasma flame probe 14 automatically identify the combustion status at and within the burner 12 outlets. If flame extinction is detected, the burner group is automatically deactivated.

[0088] In this embodiment, a gas composition analyzer 81 is provided on the clean gas pipeline 8 to analyze the clean gas composition 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 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 embodiment

[0091]

[0092] Example 2: Rapid switching of coke oven gas backup system

[0093] Emergency conditions: natural gas supply interruption;

[0094] Backup gas source: coke oven gas;

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

[0096] Emergency Response Process

[0097] 1. Gas source switching

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

[0099] Shut off oxygen and natural gas pipelines;

[0100] Automatically open the coke oven gas pressurizing device;

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

[0102] 2. Combustion parameters reset

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

[0104] Recalculate the number of burners enabled to compensate for calorific value differences;

[0105] 3. Flame stability guarantee

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

[0107] The plasma flame probe verifies the flame stability group by group;

[0108] 4. Temperature recovery

[0109] T2 returns to the set temperature, with a fluctuation range of (-3°C, 3°C);

[0110] 5.Technological advantages

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

[0112] The temperature out-of-control time is compressed to less than 6 minutes;

[0113] Multiple combustion monitoring eliminates 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 limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for controlling the temperature of top gas based on premixed combustion technology, applied to a blast furnace ironmaking process, characterized in that: The following steps are involved: S1: Real-time monitoring of the gas temperature T1 at the furnace top and the gas temperature T2 before entering the dry bag filter (7); 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 ; S3: Determine T obtained in S2 2+t Is it less than or equal to the preset dew point temperature T min ; S4: If S3 determines yes, execute the following heating steps: S41: regulating the combustible gas pressure to a target pressure; S42: premixing the combustible gas pressure-regulated in S41 with the combustion-supporting gas at the front end of the burner (12) to form a premixed gas; S43: igniting the premixed gas formed in S42, causing it to continue burning in the burner (12) to generate high-temperature flue gas; S44: introducing the high-temperature flue gas generated in S43 into the blast furnace gas enclosure (1) or the riser (3) area of ​​the blast furnace gas system to directly mix with the blast furnace gas for heat exchange; S5: During the heating process, according to the set target temperature T 2set and real-time monitored temperature, intelligently adjusting the number of burners (12) put into operation; S6: real-time monitoring of the combustion state of the burner (12) and the oxygen content of the clean coal gas, and execution of safety protection operations; Among them, in S2, the gas temperature at the inlet of the dry bag filter at the future time is T 2+t The calculation formula is: T 2+t =T1-(T 1-t -T2) Among them, T 2+t represents the gas temperature at the inlet of the dry bag dust collector after t seconds; T1 represents the gas temperature at the top of the furnace at the current moment; T2 represents the gas temperature at the inlet of the dry bag dust collector at the current moment; T 1-t It represents the furnace top gas temperature t seconds ago; t represents the time required for blast furnace gas to reach the inlet of dry bag dust collector from the furnace top.

2. The method for controlling the temperature of the furnace top gas based on the premixed combustion technology according to claim 1, characterized in that: In S2, time t is calculated by the following formula: Wherein, L1, L2, L3 and L4 are respectively the length of the riser (3), the length of the downpipe (4), the length of the straight section of the crude gas dust collector (5), and the length of the raw gas pipeline (6); V1, V2, V3 and V4 are respectively the average flow velocities of blast furnace gas in the riser (3), downcomer (4), straight section of the crude gas dust collector (5) and raw gas pipeline (6).

3. The method for controlling the temperature of the top gas based on the premixed combustion technology according to claim 1, characterized in that: The S5 specifically includes: S51: The number n of burner groups (12) initially put into operation is calculated and rounded using the following formula: Among them, T 2,0 Indicates the inlet gas temperature of the dry bag filter when premixed combustion is not enabled; T 2,N It represents the maximum gas temperature at the inlet of the dry bag filter that can be achieved by this design method; T 2set represents the set target dry bag filter inlet gas temperature; N represents the total number of groups into which the burner (12) is divided; S52: During the premixed combustion operation, calculate the average dry bag filter inlet gas temperature T in any continuous 2t period of time. 2avr With the set target temperature T 2set The difference ΔT2 = T 2avr -T 2set ; S53: If ΔT2≤b, where b is a manually set negative deviation threshold, a group of burners (12) is automatically enabled; S54: If ΔT2 ≥ c, where c is a manually set positive deviation threshold, a group of burners (12) is automatically deactivated.

4. The method for controlling the temperature of the top gas based on the premixed combustion technology according to claim 1, characterized in that: Also includes the steps: S7: During the heating process, the T obtained in S2 is judged in real time. 2+t Is it greater than or equal to the preset bag burnout temperature T max ; S8: If the answer of S7 is yes, the premixed combustion system is turned off.

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

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

7. A furnace top gas temperature control system based on premixed combustion technology, characterized by: include: The temperature monitoring unit comprises an outlet pipe thermocouple (21) provided on the outlet pipe (2) and a raw gas pipeline thermocouple (61) provided on the raw gas pipeline (6), which are used to respectively detect the furnace top gas temperature T1 and the dry bag dust collector inlet gas temperature T2 in real time; Temperature prediction and control unit: including a human-machine interface HMI and its auxiliary electrical facilities; the signal output ends 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 dry bag filter inlet gas temperature T 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 bag burnout temperature T max The comparison results and the set target temperature T 2set , generate control instructions; The combustible gas pressure regulating and delivery unit comprises a combustible gas pressure regulating device (10) and a combustible gas delivery pipeline (11), and is used to regulate the combustible gas pressure to a target pressure and deliver the combustible gas; A premixed combustion unit comprises a plurality of burners (12), a combustion-supporting gas delivery pipeline (9) and an igniter (15); the burners (12) are evenly arranged in the blast furnace gas enclosure (1) or in the same circumferential direction of the riser (3), and their inlets are respectively connected to the combustible gas delivery pipeline (11) and the combustion-supporting gas delivery pipeline (9) through pipelines, and are used to premix the pressure-regulated combustible gas and the combustion-supporting gas at the front end of the burner; the igniter (15) is arranged inside or near the burner (12), and is used to ignite the premixed gas to generate high-temperature flue gas, and the high-temperature flue gas and the blast furnace gas are directly mixed and heat-exchanged in the blast furnace gas enclosure (1) or the riser (3); the start and stop of the premixed combustion unit are controlled by the control instructions generated by the temperature prediction and control unit; A safety monitoring and protection unit comprising a fire detection device (13) and a plasma flame probe (14) for monitoring the combustion state of a burner (12), and a gas composition analyzer (81) for monitoring the oxygen content of clean coal gas; the fire detection device (13) and the plasma flame probe (14) are arranged at the outlet or inside of the burner (12), and the gas composition analyzer (81) is arranged on the clean coal gas pipeline (8); signal output ends of the fire detection device (13), the plasma flame probe (14) and the gas composition analyzer (81) are connected to the temperature prediction and control unit or the direct interlocking control device; Wherein, the temperature prediction and control unit is further configured to: according to the set target temperature T 2set , Dry bag filter inlet gas temperature T when premixed combustion unit is not enabled 2,0 And the maximum temperature T that the system can achieve 2,N , calculate the number of burner groups initially put into operation; during the operation of the premixed combustion unit, according to the average dry bag filter inlet gas temperature T in a continuous time period 2avr With T 2set and when receiving a flame outage signal or a clean gas oxygen content exceeding standard signal sent by the safety monitoring and protection unit, executing a corresponding safety protection operation.

8. The furnace top gas temperature control system based on premixed combustion technology according to claim 7 is characterized in that: The safety monitoring and protection unit further comprises an infrared thermal imager (16), which is arranged above the blast furnace gas enclosure (1) and has a signal output end connected to the temperature prediction and control unit or the operating station for observing 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 the 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, a combustion-supporting gas supply valve and an igniter (15), and is independently 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 further comprises an outlet pipe pressure transmitter (22) provided on the outlet pipe (2) and a raw gas pipeline pressure transmitter (62) provided 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; and the combustion-supporting gas is oxygen or compressed air.

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