A heat preservation method for a blast furnace hearth masonry construction

Abstract

A heat preservation method for a blast furnace hearth masonry construction belongs to the technical field of iron-making blast furnace masonry construction. The method comprises the following steps: S1. confirming the preconditions for the hearth refractory masonry construction: A. the construction hoistway for the hearth masonry construction is installed, and the hearth forms a relatively closed construction space; B. a thermometer is arranged in the hearth; C. the hearth cooling wall has water supply conditions; D. the hearth cooling wall body temperature measuring thermocouple is installed; S2. hot medium is supplied to the hearth cooling system loop, and the hearth cooling wall body temperature is controlled to be 40-70 DEG C; S3. the hot medium flow, temperature or tuyere cold air inlet amount supplied to the hearth cooling system loop is regulated and controlled, the hearth cooling wall body temperature is controlled, and the construction environment temperature in the hearth is controlled to be 5-40 DEG C. During the hearth masonry construction, the heated medium is supplied to the hearth circulating cooling water system, the hearth cooling wall temporarily plays the role of a heating radiator, the operation cost is low, the operation is simple, and the effect is good.

Description

Technical Field

[0001] This invention relates to a heat preservation method for blast furnace hearth construction, belonging to the technical field of blast furnace construction. Background Technology

[0002] Hearth lining is required for both new blast furnace construction and major blast furnace overhauls. The construction of the blast furnace hearth has specific temperature requirements, especially for the application of monolithic carbon ramming refractories and carbon oil linings. For example, the application temperature for carbon ramming refractories with resin-based binders is generally 5-40℃, while that for those with tar-based binders is 20-40℃. Failure to meet these temperature requirements will affect the performance of the refractory materials, impacting not only the construction quality but also increasing the thermal resistance of the hearth gap and shortening its service life. In winter, especially in northern regions where temperatures are often low, typically reaching -10 to -30℃, insulation during hearth lining construction becomes even more crucial.

[0003] In traditional blast furnace hearth construction, a refractory insulation shed is typically installed near the furnace, housing heating and insulation facilities. While this provides some insulation, the heat stored in the refractory material dissipates rapidly during its transfer from the shed to the furnace. By the time the refractory reaches the furnace, its surface temperature has essentially dropped to ambient temperature, rendering the insulation ineffective. Furthermore, the blast furnace hearth cooling wall experiences significant temperature differences before and after start-up, typically exceeding 20°C in summer and reaching 60-70°C in winter. After start-up, the cooling wall temperature rises sharply, causing thermal expansion and deformation. Due to the different coefficients of thermal expansion between the cooling wall and the refractory material, air gaps may form between them, increasing the thermal resistance of heat transfer and reducing the hearth's cooling efficiency, thus impacting its lifespan. Therefore, a suitable insulation method for blast furnace hearth construction is urgently needed. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems in the prior art and provide a heat preservation method for the construction of blast furnace hearth, so as to take effective temperature raising and heat preservation measures during the construction of blast furnace hearth in winter.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: The heat preservation method for blast furnace hearth construction of the present invention includes the following steps: S1. Confirm the prerequisites for furnace hearth refractory lining construction: A. The construction platform inside the blast furnace to be built has been installed, and the hearth has formed a relatively closed construction space; B. A thermometer is installed inside the furnace hearth to monitor the temperature of the relatively enclosed construction environment formed inside the furnace hearth in real time; C. The furnace cooling wall is equipped with water circulation; D. The temperature measuring thermocouples on the hearth cooling wall are installed, and the temperature monitoring results can be displayed online on the computer in the blast furnace control room.

[0006] S2. Connect a heat medium supply pipe to the furnace cooling wall water supply ring pipe and a heat medium return pipe to the furnace cooling wall water return ring pipe; connect a heat medium supply pipe to the water inlet end of the furnace bottom water cooling pipe and a heat medium return pipe to the water return end of the furnace bottom water cooling pipe.

[0007] S3. Heat medium is supplied to the furnace cooling wall cooling system through the heat medium supply pipeline to control the furnace cooling wall temperature between 40℃ and 70℃.

[0008] S4. Adjust parameters such as the flow rate and temperature of the heat medium entering the furnace cooling system or the amount of cold air entering the tuyeres to control the temperature of the furnace cooling wall, thereby controlling the construction environment temperature inside the furnace between 5℃ and 40℃.

[0009] The above-mentioned insulation method for the blast furnace hearth construction, in step S1, the furnace cooling wall having water supply conditions means that the furnace bottom water cooling pipe, hearth, and furnace cooling wall have all been installed, the furnace hearth and furnace cooling system water supply and return water form a complete circulation loop, the system has no leakage, and the water supply volume and water temperature can be regulated by the valves in the water supply system, while the wall temperature is monitored by the thermocouple of the cooling wall.

[0010] In the above-mentioned heat preservation method for the construction of the blast furnace hearth, in step S1, there are two thermometers in the hearth, which are respectively set on opposite sides of the hearth. The thermometers have a range of 0 to 100℃ and an accuracy of 0.1℃.

[0011] In the above-mentioned heat preservation method for the construction of blast furnace hearth, the heat medium mentioned in step S3 is hot water, steam or hot flue gas. The heat medium will not threaten the safety of construction personnel inside the furnace, nor will it cause corrosion problems to the hearth cooling system.

[0012] The above-mentioned insulation method for blast furnace hearth construction, in step S4, involves regulating the flow rate of the heat medium entering the furnace cooling system using valves controlled by the furnace cooling system. The monitoring devices for the temperature and pressure of the heat medium are also the existing monitoring devices for the cooling water in the furnace cooling system. In other words, the regulating devices (valve, etc.) and monitoring devices (temperature, pressure, etc.) for the cooling water in the furnace cooling system are also applicable to the control and monitoring of the heat medium.

[0013] The above-mentioned insulation method for the construction of the blast furnace hearth, the step S4 of regulating the cold air volume of the tuyeres, involves installing adjustable baffles at the tuyeres and controlling the natural air volume of each tuyer by adjusting the baffle opening. One or two tuyeres are equipped with axial flow fans to increase the forced air volume.

[0014] The beneficial effects of this invention are as follows: During the construction of the blast furnace hearth, a circulating cooling water system is used to introduce a heating medium, allowing the hearth cooling wall to temporarily function as a "radiator," replacing the traditional external insulation shed for heat preservation of the hearth refractory material. This avoids the disadvantages of temperature drop during refractory material transportation and ensures the temperature requirements of the refractory material during the construction process. Experiments have shown that using the method of this invention can increase the wall temperature of the hearth cooling wall by 35-100℃. For example, if insulation measures are taken when the ambient temperature is <5℃, controlling the cooling wall temperature to reach 40℃ will increase the wall temperature by 35℃; if the ambient temperature is as low as -30℃, controlling the cooling wall temperature to reach 70℃ will increase the wall temperature by 100℃. This reduces the temperature difference of the hearth cooling wall before and after furnace start-up to 0-10℃, allowing the thermal expansion of the cooling wall to be released in advance, effectively reducing the thermal resistance of the hearth air gap, improving heat transfer in the hearth, and thus contributing to a longer hearth lifespan.

[0015] The method of this invention has the advantages of simple process, low modification and operation cost, easy operation, and good temperature raising and heat preservation effect. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a heat preservation method for blast furnace hearth construction according to an embodiment of the present invention; The markings in the diagram are: 1. Heat medium supply pipe; 2. Furnace body cooling wall water supply ring pipe; 3. Tubular outlet; 4. Hanging platform; 5. Furnace body cooling wall return water ring pipe; 6. Heat medium return pipe; 7. Furnace bottom heat medium supply pipe; 8. Furnace bottom water cooling pipe; 9. Furnace bottom heat medium return pipe; 10. Valve. Detailed Implementation

[0017] Example 1: A newly built 3200m² in northern China 3In winter, the hearth lining construction is carried out at around -25℃. Before construction, the hearth, furnace cooling system, and bottom water-cooled pipe 8 have been installed and debugged. The furnace body and hearth cooling walls have also been installed and are ready for water supply. The hoisting platform 4 for the lining construction in the furnace belly has been installed. Of the 32 tuyeres 3, except for tuyere platforms #2 and #18 which are reserved for transferring refractory materials and personnel access, the remaining 30 have been sealed with sludge from the front taphole. The heat medium supply pipe 1 is connected to the furnace cooling wall water supply ring pipe 2, and the heat medium return pipe 6 is connected to the furnace cooling wall return water ring pipe 5. The bottom heat medium supply pipe 7 is connected to the inlet end of the bottom water-cooled pipe 8, and the bottom heat medium return pipe 9 is connected to the return end of the bottom water-cooled pipe 8. The wall temperature measuring thermocouples of the hearth cooling wall have been installed, and the monitoring results are displayed in real time on the computer monitoring screen in the blast furnace control room. Two temperature gauges with a range of 100℃ and an accuracy of 0.1℃ were installed along the diameter of the hearth to monitor the ambient temperature during construction. One day before hearth construction, steam was introduced into the hearth cooling system at a pressure of 4.5 kg and a flow rate of 2500 m³ / h. After 10 hours, the temperature of the hearth cooling wall gradually increased to 67℃ and stabilized, while the ambient temperature inside the hearth reached 40℃. By adjusting and increasing the natural air intake at tuyeres #2 and #18, the temperature inside the hearth was controlled to 30–35℃. Under these temperature conditions, the refractory lining of the hearth was successfully installed. Six years after the blast furnace was put into operation, the hearth temperature stabilized, heat transfer in the hearth cooling system was smooth, and there were no signs of air gap formation, creating favorable conditions for a long service life of the hearth.

[0018] Example 2 The method of the present invention is applicable not only to furnace hearth construction in winter, but also to other seasons. Its function is to reduce the air gap thermal resistance between the hot surface of the furnace hearth cooling wall and the furnace hearth refractory.

[0019] A newly built 1580m³ blast furnace underwent hearth lining construction in autumn at an ambient temperature of approximately 5℃. Prior to construction, the construction hoist 4, installed at the furnace waist, had been completed. The bottom water-cooling pipes 8, furnace body, and hearth cooling walls had also been installed and tested, creating a relatively enclosed construction space between the hearth and the construction hoist 4. Of the 22 tuyeres 3, 2 were reserved for transferring refractory materials and personnel access, while the remaining 20 were sealed. A heat medium supply pipe 1 was connected to the furnace body cooling wall water supply ring pipe 2, and a heat medium return pipe 6 was connected to the furnace body cooling wall return water ring pipe 5. A bottom heat medium supply pipe 7 was connected to the inlet end of the bottom water-cooling pipe 8, and a bottom heat medium return pipe 9 was connected to the return end of the bottom water-cooling pipe 8. The wall temperature measuring thermocouples for the hearth cooling walls were installed, and the monitoring results were displayed in real-time on the computer monitoring screen in the blast furnace control room. Two temperature gauges with a range of 100℃ and an accuracy of 0.1℃ were installed inside the hearth to monitor the ambient temperature during construction. Two days before hearth construction, hot water was introduced into the hearth cooling system at a temperature of 48℃, a pressure of 6.5 kg, and a flow rate of 2000 m³ / h. After 7 hours, the temperature of the hearth cooling wall gradually increased to 43℃ and stabilized. The ambient temperature inside the hearth was 30℃. By increasing the natural air intake at the tuyeres, the temperature inside the hearth was maintained between 20℃ and 25℃. The hearth construction was carried out under these temperature conditions. Three to 5 years after the blast furnace was put into operation, the hearth temperature stabilized, and there were no signs of air gap formation. Example 3

[0020] A newly built 2500m³ blast furnace underwent hearth lining construction during the summer at an ambient temperature of approximately 25℃. Prior to construction, the hearth, furnace cooling system, furnace bottom cooling water pipes, and furnace body had been installed and tested. The hoisting platform 4 for the furnace belly lining construction was installed. Of the 22 tuyeres 3, 2 were reserved for transporting refractory materials and personnel access, while the remaining 20 were sealed. A heat medium supply pipe 1 was connected to the furnace body cooling wall water supply ring pipe 2, and a heat medium return pipe 6 was connected to the furnace body cooling wall return water ring pipe 5. A furnace bottom heat medium supply pipe 7 was connected to the inlet end of the furnace bottom water cooling pipe 8, and a furnace bottom heat medium return pipe 9 was connected to the return end of the furnace bottom water cooling pipe 8. Temperature measuring thermocouples for the hearth cooling wall were installed, and the monitoring results were displayed in real-time on the computer monitoring screen in the blast furnace control room. Two temperature measuring ranges of 100℃ with an accuracy of 0.1℃ were set up inside the hearth to monitor the ambient temperature during construction. The day before the hearth was constructed, hot flue gas was introduced into the hearth cooling system at a temperature of 65℃ and a flow rate of 2400 m³ / h. The temperature of the hearth cooling wall gradually increased to 48℃ and stabilized, while the ambient temperature inside the hearth was 45℃. By increasing the natural air intake at the tuyeres, the temperature inside the hearth was maintained between 30℃ and 40℃. Under these temperature conditions, the hearth was constructed. Five years after the blast furnace was put into operation, the thermocouple temperatures of each layer of the hearth remained stable, and no hearth erosion was observed.

Claims

1. A method for heat preservation during the construction of a blast furnace hearth, characterized in that, Includes the following steps: S1. Confirm the prerequisites for furnace hearth refractory lining construction: A. The construction hoisting platform (4) inside the blast furnace to be built has been installed, and the hearth has formed a relatively closed construction space; B. A thermometer is installed inside the furnace hearth to monitor the temperature of the relatively enclosed construction environment formed inside the furnace hearth in real time; C. The furnace hearth cooling wall is equipped with water circulation. D. The temperature measuring couplers of the hearth cooling wall are installed, and the temperature monitoring results can be displayed online on the computer in the blast furnace control room; S2. Connect the heat medium supply pipe (1) to the furnace cooling wall water supply ring pipe and the heat medium return pipe (6) to the furnace cooling wall return water ring pipe (5); connect the furnace bottom heat medium supply pipe (7) to the water inlet end of the furnace bottom water cooling pipe (8) and connect the furnace bottom heat medium return pipe (9) to the water return end of the furnace bottom water cooling pipe to control the furnace cylinder cooling wall temperature between 40℃ and 80℃; S3. Adjust the flow rate and temperature of the heat medium entering the furnace cooling system circuit or the cold air volume of the air inlet (3) to control the temperature of the furnace cooling wall, thereby controlling the construction environment temperature in the furnace between 5℃ and 40℃.

2. The insulation method for blast furnace hearth construction according to claim 1, characterized in that, The fact that the furnace cooling wall in step S1 has the conditions for water supply means that the furnace bottom water cooling pipe (8), furnace body and furnace cylinder cooling wall have been installed, the furnace water supply and return water system forms a complete circulation loop, the system has no leakage, and the water supply volume and water temperature can be regulated by the valve in the water supply system, while the wall temperature is monitored by the thermocouple of the cooling wall.

3. The insulation method for blast furnace hearth construction according to claim 1, characterized in that, In step S1, there are two thermometers inside the furnace cylinder, which are set on opposite sides of the furnace cylinder. The thermometers have a range of 0 to 100℃ and an accuracy of 0.1℃.

4. The insulation method for blast furnace hearth construction according to claim 1, characterized in that, The heat medium mentioned in step S3 is hot water, steam, or hot flue gas.

5. The insulation method for blast furnace hearth construction according to claim 1, characterized in that, In step S4, the flow rate of the heat medium entering the furnace cooling system loop is regulated by the furnace cooling system's regulating valve for cooling water; the monitoring device for the temperature and pressure of the heat medium is the same as the existing furnace cooling system's monitoring device for cooling water.

6. The insulation method for blast furnace hearth construction according to claim 1, characterized in that, The control of the air intake volume of the air outlet mentioned in step S4 is to install an adjustable baffle on the air outlet (3) and control the natural air intake volume of each air outlet by adjusting the baffle opening. Among them, axial flow fans are set on 1-2 air outlets to increase the forced air intake volume.

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