Method for optimizing furnace top water fetching system of hydrogen-rich carbon circulating oxygen blast furnace and improving cooling capacity

Abstract

The invention belongs to the technical field of blast furnace ironmaking equipment and process safety control, and particularly discloses a method for optimizing a hydrogen-carbon-rich circulating oxygen blast furnace top water fetching system and improving cooling capacity, which aims at the characteristics of high thermal load, complex heat source and strict temperature control requirements under extreme working conditions such as shutdown of a HyCROF blast furnace. The problems that an existing water fetching system is insufficient in cooling capacity redundancy and poor in reliability are fundamentally solved through capacity accounting of the water fetching system based on the limit thermal load, key equipment upgrading, hierarchical and partitioned water fetching control strategy making and linkage of the water fetching system and process operation. The method can ensure that the furnace top temperature of the HyCROF blast furnace is strictly controlled in a safe range under extreme working conditions, provides a solid guarantee for equipment safety and process stability, and has the advantages of intelligent control, water resource saving and prospective adaptation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of safety control of blast furnace ironmaking equipment and process, in particular to a hydrogen-rich carbon-circulation oxygen blast furnace top water injection system optimization and cooling capacity improvement method. BACKGROUND

[0002] The top water injection system is a key safety facility for controlling the temperature of the furnace top under special conditions such as furnace shutdown and furnace soaking. Its working principle is to spray atomized water into the furnace top space, use the heat absorption of water vaporization to quickly reduce the gas temperature, protect the furnace top equipment and gas pipeline from being damaged by high temperature, and prevent accidents caused by excessive temperature.

[0003] For traditional blast furnaces, the capacity of the conventional designed water injection system is usually configured based on the heat load during normal production. However, the HyCROF blast furnace presents different thermal characteristics during shutdown: Higher heat load: Due to the injection of high-temperature decarburization gas and high metalization rate of furnace charge, the heat accumulated in the furnace during the initial shutdown is much larger than that of traditional blast furnaces.

[0004] More complex heat source: In addition to coke combustion and hot air, there is also sensible heat and chemical heat of decarburization gas.

[0005] More stringent temperature control requirements: In order to prevent hydrogen explosion and other risks, the furnace top temperature needs to be strictly controlled in a lower range (such as ≤350℃).

[0006] In the first HyCROF shutdown practice of a 2500m³ A blast furnace, although the temperature control was successful in the end, the actual water injection volume (1688m³) was close to the capacity limit of the original system, and due to the unexpected heat load, the top temperature once reached the upper limit. This exposed the problem that the existing water injection system had insufficient cooling capacity redundancy and poor system reliability when dealing with extreme conditions of HyCROF blast furnace. Once the water injection system fails or is insufficient, the consequences will be disastrous.

[0007] Therefore, it is necessary to conduct comprehensive capacity calculation and optimization and upgrading of the top water injection system for the special nature of the HyCROF blast furnace. SUMMARY

[0008] The purpose of the present application is to provide a hydrogen-rich carbon-circulation oxygen blast furnace top water injection system optimization and cooling capacity improvement method, which ensures that the water injection system can still provide sufficient and reliable cooling protection under extreme conditions through systematic capacity calculation, key equipment upgrading and temperature control strategy optimization.

[0009] To achieve the above purpose, the basic scheme provided by the present application is: a hydrogen-rich carbon-circulation oxygen blast furnace top water injection system optimization and cooling capacity improvement method, comprising the following steps: S1: Water injection system capacity calculation based on the limit heat load Adopt the conservative principle, and take the maximum comprehensive air volume, decarburization gas volume and the highest theoretical combustion temperature at the initial stage of shutdown as the input conditions to calculate the maximum theoretical water injection volume G_max; The calculation formula is: G_max=(V_maxxC_hXT_b) / (q_1+q_2); Wherein, V_max is the estimated limit blast volume, including hot blast, oxygen and decarburization gas; T_b is 1800-2000℃; q_1 is the latent heat of water evaporation; q_2 is the heat required for water vapor to superheat to the top control temperature of the furnace; The G_max is taken as the design reference flow of the water injection system upgrading and reconstruction; S2: Upgrading of key equipment of the water injection system S2.1 Pump set capacity upgrading: The furnace top water injection pump set is calculated and upgraded to ensure that the total rated flow of the pump set is >1.2x G_max, and the rated outlet pressure of the pump set is >2.0MPa; S2.2 Water injection gun replacement: The original ordinary water injection guns are replaced with high-flow and high-efficiency atomizing type water injection guns, the flow of the new type of water injection gun is increased by more than 50%, and the spiral vortex or gas-assisted atomization structure is adopted; S2.3 Pipeline and valve inspection: The supply water main pipeline, branch pipeline and control valve of the water injection system are calculated and pressure checked to ensure that they meet the flow and pressure requirements after upgrading; S3: Establishing a hierarchical and zoned water injection control strategy The furnace top water injection guns are divided into at least two independently controlled zones; the hierarchical control logic is developed: When T_top≤300℃, it is first-level control, and the specific control method is to maintain a small number of water injection guns intermittently working or closed; When 300℃ When T_top>330℃ or the temperature rises too fast, it is third-level control, and the specific control method is to start all the water injection guns in all zones to cool at the maximum flow; wherein T_top represents the top temperature of the furnace; S4: Linkage of the water injection system and process operation The water injection system control is linked with the key process parameters of the comprehensive air volume and decarburization gas flow of the blast furnace; when the "wind reduction temperature control" strategy is adopted in operation, the water injection control system automatically receives the wind reduction signal, and adjusts the set value of the water injection flow according to the preset model.

[0010] Further, in step S2.2, the single-gun flow of the high-flow and high-efficiency atomizing type water injection gun is not less than 3.5 m³ / h, and the jet opening angle is greater than 90°.

[0011] Further, in step S3, the arrangement of the water lances at the top of the furnace adopts a symmetrical and uniform scheme, ensuring that there are no cooling dead angles in the space at the top of the furnace.

[0012] Compared with the prior art, the present application has the following advantages: 1. By accounting based on the limit heat load and equipment upgrading, the hidden danger of insufficient water cooling system capacity is fundamentally solved, and a solid hardware foundation is provided for HyCROF blast furnace safe shutdown.

[0013] 2. Pump group redundancy design and water lance partition control, even if part of the equipment fails, the system can still maintain basic cooling function, and the reliability is greatly improved.

[0014] 3. Hierarchical partitioning strategy and air-water linkage make the water cooling control from extensive to fine, which not only ensures the cooling effect, but also avoids water resource waste and other problems that may be caused by excessive water cooling.

[0015] 4. The method is not only suitable for shutdown, but also provides safety redundancy for other high load conditions (such as extreme furnace condition treatment) that the HyCROF blast furnace may encounter in the future. BRIEF DESCRIPTION OF DRAWINGS

[0016] Fig. 1 is the water cooling system optimization and capacity improvement implementation flowchart provided by the embodiment of the present application; Fig. 2 is the hierarchical partitioning water cooling control logic diagram provided by the embodiment of the present application; Fig. 3 is the upgraded water cooling system schematic diagram provided by the embodiment of the present application. DETAILED DESCRIPTION

[0017] The present application will be further described in detail through specific embodiments: As shown in Figs. 1 to 3 A hydrogen-rich carbon cycle oxygen blast furnace top water cooling system optimization and cooling capacity improvement method, comprising the following steps: S1: water cooling system capacity accounting based on limit heat load Adopting the conservative principle, taking the maximum comprehensive air volume at the initial stage of shutdown, the decarburization gas volume and the highest theoretical combustion temperature as the input conditions, the maximum theoretical water cooling volume G_max is calculated; The calculation formula is: G_max=(V_maxxC_hT_b) / (q_1+q_2); Wherein, V_max is the estimated limit blast volume, including hot blast, oxygen and decarburization gas; T_b is 1800-2000℃; q_1 is the latent heat of water evaporation; q_2 is the heat required for water vapor to be superheated to the top of the furnace control temperature; G_max as the design reference flow of the water injection system upgrade; S2: Upgrade of key equipment of water injection system S2.1 Pump set capacity upgrade: Calculate and upgrade the furnace top water injection pump set to ensure that the total rated flow of the pump set is >1.2 x G_max, and the rated outlet pressure of the pump set is >2.0 MPa; S2.2 Water injection gun replacement: Replace all original ordinary water injection guns with high-flow and high-efficiency atomizing type water injection guns. The single gun flow of the new type of water injection gun is increased by more than 50%, and the spiral vortex or gas-assisted atomizing structure is adopted. The single gun flow of the high-flow and high-efficiency atomizing type water injection gun is not less than 3.5 m³ / h, and the jet angle is greater than 90°; S2.3 Pipeline and valve inspection: Calculate the diameter and pressure-bearing inspection of the water injection system's main water supply pipeline, branch pipeline and control valve to ensure that they meet the flow and pressure requirements after upgrading; S3: Establish a hierarchical and zoned water injection control strategy The arrangement of water injection guns on the furnace top adopts a symmetrical and uniform scheme to ensure that there are no cooling dead angles in the furnace top space. The furnace top water injection guns are divided into at least two independently controlled zones. The hierarchical control logic is developed as follows: When T_top≤ 300℃, it is first-level control, and the specific control method is to maintain a small number of water injection guns working intermittently or closed; When 300℃<T_top≤330℃, it is second-level control, and the specific control method is to start the water injection guns in one zone to work continuously; When T_top> 330℃ or the temperature rises too fast, it is third-level control, and the specific control method is to start all the water injection guns in all zones to cool at the maximum flow. Wherein T_top represents the furnace top temperature; S4: Linkage of water injection system and process operation Link the water injection system control with the key process parameters of the comprehensive blast volume and decarburization gas flow of the blast furnace. When the "reduce wind to control temperature" strategy is adopted in operation, the water injection control system automatically receives the wind reduction signal and adjusts the set value of the water injection flow according to the preset model.

[0018] The specific example of the optimization of the water injection system after the HyCROF mode shutdown of a 2500m³A blast furnace in a certain steel enterprise is as follows: I. Capacity calculation (corresponding to S1) Based on the first shutdown data, the maximum comprehensive wind volume of 3800 Nm³ / min is taken, and a certain surplus coefficient is considered to calculate the maximum theoretical water injection volume G_max. After calculation, G_max is about 220 m³ / h.

[0019] The original water injection system has 8 guns, with a single gun flow of about 1.8 m³ / h and a total capacity of about 14.4 m³ / h, which is far lower than G_max, which is the direct reason for the difficulty in temperature control during the first shutdown.

[0020] II. Equipment upgrade (corresponding to S2) Pump set upgrade: add or replace the water cannon pump set, so that the total rated flow reaches ≥1.2x220=264m³ / h, and the pump outlet pressure is raised to 2.5MPa.

[0021] Water cannon replacement: purchase and replace 8 new high-flow efficient atomizing water cannons, with a single gun flow of 4.0m³ / h, a total theoretical maximum flow of 32m³ / h, meeting the G_max requirement, and better atomization effect.

[0022] Pipeline inspection: The water supply pipeline is flushed and pressure tested to confirm that it can withstand the pressure and flow of the new pump set.

[0023] III. Control strategy development (corresponding to S3) Divide the 8 guns into A zone (4) and B zone (4), and use symmetric and uniform arrangement, with specific control as follows: Ttop≤300℃: water cannon system on standby or single gun rotation; 300℃<Ttop≤ 330℃: automatically start 4 guns in A zone; Ttop>330℃ or temperature rise exceeds 20℃ within 5 minutes: automatically start all 8 guns in A+B zone.

[0024] IV. Linkage scheme (corresponding to S4) Establish a logic in the DCS system: when the integrated air volume is switched from high gear (such as >3500 Nm³ / min) to low gear (such as <2500 Nm³ / min), the set value of water flow is automatically reduced by 15% to avoid excessive cooling.

[0025] After the above optimization scheme, the cooling capacity of the water cannon system of A blast furnace has been greatly improved, providing reliable safety guarantee for subsequent HyCROF operation.

[0026] The above is only an embodiment of the present application, and well-known specific structures and properties in the scheme are not described in detail. It should be noted that for those skilled in the art, without departing from the structure of the present application, a number of modifications and improvements can be made, which should be considered as the protection scope of the present application, which will not affect the effect and practicality of the patent. The protection scope claimed in this application should be subject to the content of its claims, and the specific implementation mode and the like in the specification can be used to explain the content of the claims.

Claims

1. A method for optimizing and improving the cooling capacity of a hydrogen-rich carbon-circulating oxygen blast furnace top water supply system, characterized in that, It includes the following steps: S1: Calculation of the water injection system capacity based on the ultimate heat load Adopting the conservative principle, taking the maximum comprehensive air volume, decarbonized gas volume and the highest theoretical combustion temperature at the initial stage of furnace shutdown as input conditions, calculate the maximum theoretical water injection volume G_max; The calculation formula is: G_max = (V_max × C_h × T_b) / (q_1 + q_2); Where, V_max is the estimated ultimate blast volume, including hot air, oxygen, and decarbonized gas; T_b is taken as 1800 - 2000 °C; q_1 is the latent heat of vaporization of water; q_2 is the heat required for superheating water vapor to the furnace top control temperature; The G_max is used as the design reference flow rate for the upgrade and transformation of the water injection system; S2: Upgrade of key equipment in the water injection system S2.1 Upgrade of pump group capacity: Conduct accounting and upgrade on the water injection pumps at the furnace top to ensure that the total rated flow rate of the pump group > 1.2 × G_max, and the rated outlet pressure of the pump group > 2.0 MPa; S2.2 Replacement of water injection nozzles: Replace all the original ordinary water injection nozzles with large-flow, high-efficiency atomizing water injection nozzles. The single-nozzle flow rate of the new water injection nozzles is increased by more than 50%, and a spiral vortex or gas-assisted atomization structure is adopted; S2.3 Inspection of pipelines and valves: Conduct diameter calculation and pressure-bearing inspection on the main water supply pipelines, branch pipelines and control valves of the water injection system to ensure that they meet the flow rate and pressure requirements after upgrade; S3: Establish a hierarchical and zonal water injection control strategy Divide the water injection nozzles at the furnace top into at least two independently controlled zones; formulate hierarchical control logic: When T_top ≤ 300 °C, it is the first-level control. The specific control method is: maintain a small number of water injection nozzles to work intermittently or be closed; When 300 °C < T_top ≤ 330 °C, it is the second-level control. The specific control method is: start the water injection nozzles in one zone to work continuously; When T_top > 330 °C or the temperature rise is too fast, it is the third-level control. The specific control method is: start all the water injection nozzles in all zones simultaneously to cool at the maximum flow rate; where T_top represents the furnace top temperature; S4: Linkage between the water injection system and process operations Link the control of the water injection system with key process parameters such as the comprehensive air volume of the blast furnace and the decarbonized gas flow rate; when the "reduce air volume and control temperature" strategy is adopted in operation, the water injection control system automatically receives the reduce air volume signal and accordingly reduces the set value of the water injection flow rate according to the preset model.

2. The method for optimizing and improving the cooling capacity of the top water supply system of a hydrogen-rich carbon-circulating oxygen blast furnace according to claim 1, characterized in that, In step S2.2, the single-nozzle flow rate of the large-flow high-efficiency atomizing water injection nozzle is not less than 3.5 m³ / h, and the spray angle is greater than 90°.

3. The method for optimizing and improving the cooling capacity of the top water supply system of a hydrogen-rich carbon-circulating oxygen blast furnace according to claim 1, characterized in that, In step S3, the water injection nozzles are arranged symmetrically and evenly on the furnace top to ensure that there is no cooling dead angle in the furnace top space.

Images