A heat preservation method for hot blast stove during overhaul of blast furnace

Abstract

The application discloses a heat preservation method for hot blast furnace during overhaul of a blast furnace, and belongs to the technical field of metallurgy, which solves the technical problem that a blower needs to be started at all times during the overhaul of the blast furnace, and the method is as follows: a combustion-supporting fan is connected with the hot blast furnace through a combustion-supporting air pipeline, a blast supply pipeline, which is communicated with the tail ends of a waste gas induced draft pipeline, is installed on the combustion-supporting air pipeline, a diffusion valve is installed on the combustion-supporting air pipeline, a first butterfly valve, a first sight glass valve and a first flowmeter are installed on the blast supply pipeline, a second butterfly valve and a second sight glass valve are installed on the waste gas induced draft pipeline, a high-temperature induced draft fan is communicated with the blast supply pipeline and is disconnected with the waste gas induced draft pipeline, when the furnace is fired, the diffusion valve is opened, and the first butterfly valve and the first sight glass valve are closed, when the furnace is stewed, the diffusion valve, the first butterfly valve, the first sight glass valve, the second butterfly valve and the second sight glass valve are closed, and when blast supply is performed, the diffusion valve, the first butterfly valve, the first sight glass valve, the second butterfly valve and the second sight glass valve are opened, and the diffusion valve is used to perform blast supply at a specified air volume.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metallurgy, more particularly, it relates to a new heat preservation method for hot blast stove during blast furnace overhaul. BACKGROUND

[0002] At present, in order to ensure the temperature of the hot blast stove's arch and grate to be appropriate during the blast furnace overhaul, as shown in the prior art, on the one hand, the combustion air fan A is started to help the hot blast stove B to burn the furnace, and on the other hand, after the furnace is burned, the blast fan C in the fan room must still be started to blow air, and then the air is discharged into the atmosphere through the backflow cooling pipe D. Figure 1

[0003] The biggest disadvantage of this method is that the blast fan must be started at all times, and cannot be stopped during the blast furnace overhaul, which obviously wastes electricity consumption. Moreover, the process is relatively long, and the blast fan needs more manpower to operate during the maintenance period. SUMMARY

[0004] The present application aims at solving the above-mentioned problems of the prior art, and provides a new heat preservation method for hot blast stove during blast furnace overhaul.

[0005] The technical scheme of the present application is as follows: a new heat preservation method for hot blast stove during blast furnace overhaul, comprising:

[0006] The combustion air fan is connected with the hot blast stove through a combustion air pipeline, a blast pipe which is in communication with the end of the waste gas induction pipeline is installed on the combustion air pipeline, a diffusion valve is installed on the combustion air pipeline between the blast pipe and the hot blast stove, a first butterfly valve, a first sight glass valve and a first flowmeter are respectively installed on the blast pipe, a second butterfly valve and a second sight glass valve are respectively installed on the waste gas induction pipeline, the inlet of a high-temperature induction fan is in communication with one end of the blast pipe close to the waste gas induction pipeline, and the inlet of the high-temperature induction fan is disconnected from the waste gas induction pipeline.

[0007] During the blast furnace overhaul,

[0008] When burning the furnace, the diffusion valve is opened, and the first butterfly valve and the first sight glass valve are closed, and the combustion air fan supplies air to the hot blast stove through the combustion air pipeline;

[0009] When stewing the furnace, the diffusion valve, the first butterfly valve, the first sight glass valve, the second butterfly valve and the second sight glass valve are closed;

[0010] When blowing air, the diffusion valve, the first butterfly valve, the first sight glass valve, the second butterfly valve and the second sight glass valve are opened, and the opening degree of the diffusion valve is adjusted according to the first flowmeter, so that the diffusion valve blows air at a specified air volume.

[0011] As a further improvement, the first butterfly valve and the second butterfly valve are both Z41T-10. ​

[0012] Furthermore, during the blast furnace overhaul, the hot blast stove is kept warm by repeatedly cycling through "burning the furnace → shutting down the furnace → blowing air → shutting down the furnace," with no air blowing during burning the furnace and no burning the furnace during blowing air.

[0013] Furthermore, the control of gas and air volume during the hot blast stove firing process is as follows: instantaneous gas volume ≤ 15000 m³ / h 3 / h, total daily gas consumption ≤270,000 m³ 3 Instantaneous air volume is 9900–11000 m³. 3 / h; the number of times the hot blast stove is fired up per day shall not exceed 3 times, and the firing time for each time shall not exceed 2 hours.

[0014] Furthermore, the control of gas and air volume during the hot blast stove firing process is as follows: instantaneous gas volume

[0015] =15000m 3 / h, instantaneous air volume = 10000m³ 3 / h.

[0016] Furthermore, air is supplied at a pressure of ≤5 kPa.

[0017] Furthermore, the diameter of the air supply duct is Φ300.

[0018] Furthermore, a hot air duct is installed in the hot air furnace, with an upward flared end at the upper end of the hot air duct and insulation cotton wrapped around the outside of the hot air duct. When the hot air furnace is venting and supplying air, the backflow valve of the backflow duct is closed, and the hot air is discharged through the hot air duct.

[0019] Beneficial effects

[0020] Compared with the prior art, the advantages of this invention are as follows:

[0021] 1. It can significantly reduce the power consumption of blowers, which is dozens of times more than that of combustion fans.

[0022] 2. It can deliver air in a short flow path, saving manpower and resources for operating the blower.

[0023] 3. The blower can be stopped for maintenance. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the existing technology;

[0025] Figure 2 This is a schematic diagram of the structure of the present invention;

[0026] Figure 3 This is a schematic diagram of the hot air duct in this invention.

[0027] Among them: 1-combustion fan, 2-combustion air duct, 3-hot air furnace, 4-exhaust gas duct, 5-air supply duct, 6-vent valve, 7-first butterfly valve, 8-first spectacle valve, 9-first flow meter, 10-second butterfly valve, 11-second spectacle valve, 12-high temperature induced draft fan, 13-hot air duct, 14-upward bell mouth, 15-flue valve, 16-blind plate valve. Detailed Implementation

[0028] The present invention will be further described below with reference to specific embodiments shown in the accompanying drawings.

[0029] See Figures 2-3 A novel heat preservation method for hot blast stoves during blast furnace overhaul, comprising:

[0030] Combustion blower 1 is connected to hot air furnace 3 via combustion air duct 2. A supply air duct 5, connected to the end of exhaust gas duct 4, is installed on combustion air duct 2. Specifically, supply air duct 5 is installed after combustion air duct 2 passes through a preheater (preheater is existing technology and not shown). A vent valve 6 is installed on combustion air duct 2 between supply air duct 5 and hot air furnace 3. A first butterfly valve 7, a first spectacle valve 8, and a first flow meter 9 are installed on supply air duct 5. A second butterfly valve 10 and a second spectacle valve 11 are installed on the induced draft duct 4 respectively; the inlet of the high temperature induced draft fan 12 is connected to the end of the air supply duct 5 near the exhaust gas induced draft duct 4, and the inlet of the high temperature induced draft fan 12 is disconnected from the exhaust gas induced draft duct 4, that is, the end of the inlet pipe of the high temperature induced draft fan 12 near the hot air furnace 3 is sealed by welding with an iron plate, a flue valve 15 is provided at the end of the exhaust gas induced draft duct 4 near the high temperature induced draft fan 12, and a blind valve 16 is also provided at the inlet of the high temperature induced draft fan 12.

[0031] During the blast furnace overhaul

[0032] During furnace firing: open the venting valve 6, close the first butterfly valve 7 and the first spectacle valve 8, and the combustion air blower 1 supplies air to the hot blast stove 3 through the combustion air pipe 2;

[0033] When the oven is being sealed: close the vent valve 6, the first butterfly valve 7, the first spectacle valve 8, the second butterfly valve 10, and the second spectacle valve 11;

[0034] When supplying air: open the venting valve 6, the first butterfly valve 7, the first spectacle valve 8, the second butterfly valve 10, and the second spectacle valve 11, and adjust the opening of the venting valve 6 according to the first flow meter 9 so that the venting valve 6 supplies air at the specified air volume.

[0035] This invention eliminates the need for blowers for hot blast stove insulation during blast furnace overhauls, instead utilizing only the stove's combustion air. The combustion air serves two purposes: firstly, it powers the hot blast stove, and secondly, it supplies air to the stove after the furnace has finished firing. Since the blast furnace only requires heat for insulation, this is sufficient to meet the hot blast stove's insulation needs. This significantly reduces the power consumption of blowers, which are dozens of times more expensive than combustion air; it enables short-flow air supply, saving manpower and resources for blower operation; and it allows the blower to be stopped for maintenance.

[0036] In this embodiment, both the first butterfly valve 7 and the second butterfly valve 10 are model Z41T-10.

[0037] During the blast furnace overhaul, the hot blast stove 3 is kept warm by repeatedly cycling through "burning the furnace → shutting down the furnace → blowing air → shutting down the furnace", with no air blowing during burning the furnace and no burning the furnace during blowing air.

[0038] During the firing process of hot blast stove 3, the control of gas and air volume is as follows: instantaneous gas volume ≤ 15000 m³ / h 3 / h, total daily gas consumption ≤270,000 m³ 3 Instantaneous air volume is 9900–11000 m³. 3 / h; the number of times the hot blast stove 3 is fired up per day shall not exceed 3 times, and the firing time for each time shall not exceed 2 hours.

[0039] Preferably, the control of gas and air volume during the combustion process of hot blast stove 3 is as follows: instantaneous gas volume

[0040] =15000m 3 / h, instantaneous air volume = 10000m³ 3 / h.

[0041] When supplying air, the air pressure should be ≤5Kpa. The specific value of the air pressure should be based on the principle of effectively cooling the furnace and not affecting the air outlet. The diameter of the air supply duct 5 is Φ300.

[0042] Furthermore, a hot air duct 13 is provided in the hot air furnace 3, an upward flared mouth 14 is provided at the upper end of the hot air duct 13, and insulation cotton is provided around the hot air duct 13. When the hot air furnace 3 is exhausting air, the backflow shut-off valve of the backflow shut-off duct is closed, and the hot air is discharged through the hot air duct 13.

[0043] Specifically, after the blast furnace is shut down, hot blast ducts are installed at tuyeres 17 (No. 7) and 18 (No. 9) of hot blast stove 3, while the remaining tuyeres are sealed with blind flanges. After tuyeres 17 (No. 7) and 18 (No. 9) are sealed with blind flanges, a Φ200mm hole is opened and connected with a Φ200mm steel pipe. The steel pipe is first connected to the ground, with a length of 1.3m. Then, the two steel pipes are connected and connected with a Φ300 steel pipe, which is then extended to the tuyere platform, with a length of 12m. An upward outlet duct is welded to the end, and an upward flared end 14 is set at the upper end of the upward outlet duct to discharge the exhaust gas. The Φ200mm steel pipe, the Φ300 steel pipe, and the upward outlet duct constitute the hot blast duct 13.

[0044] During the blast furnace overhaul

[0045] Under normal conditions, the flue temperature should be <380℃, the dome temperature >900~1300℃, the baking dome temperature must not be lower than 900℃, and the silica brick interface temperature must be >650℃. When pipe insulation is not required, a closed-furnace cooling method can be used.

[0046] If the flue temperature exceeds 380℃, the dome temperature is less than 900℃, or the silica brick interface temperature is less than 650℃, the combustion fan 1 can be used to supply air through the air supply pipe 5, the hot air furnace 3, and the hot air valve (the hot air valve is existing technology). The furnace should be restarted only after the grate temperature has decreased; otherwise, combustion should be stopped. At this time, the dome temperature should be closely monitored and should not be lower than 850℃, otherwise there is a possibility that the gas will not ignite.

[0047] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention, and these will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.

Claims

1. A method for heat preservation of hot blast stoves during blast furnace overhaul, characterized in that, include: A combustion blower (1) is connected to a hot air furnace (3) via a combustion air duct (2). An air supply duct (5) connected to the end of an exhaust gas duct (4) is installed on the combustion air duct (2). A vent valve (6) is installed on the combustion air duct (2) between the air supply duct (5) and the hot air furnace (3). A first butterfly valve (7), a first spectacle valve (8), and a first flow meter (9) are installed on the air supply duct (5). A second butterfly valve (10) and a second spectacle valve (11) are installed on the exhaust gas duct (4). The inlet of a high-temperature blower (12) is connected to the end of the air supply duct (5) near the exhaust gas duct (4), and the inlet of the high-temperature blower (12) is disconnected from the exhaust gas duct (4). During the blast furnace overhaul When the furnace is being fired: open the venting valve (6), close the first butterfly valve (7) and the first spectacle valve (8), and the combustion blower (1) supplies air to the hot blast furnace (3) through the combustion air pipe (2); When the oven is being sealed: close the vent valve (6), the first butterfly valve (7), the first spectacle valve (8), the second butterfly valve (10), and the second spectacle valve (11); When supplying air: open the vent valve (6), the first butterfly valve (7), the first spectacle valve (8), the second butterfly valve (10), and the second spectacle valve (11), and adjust the opening of the vent valve (6) according to the first flow meter (9) so that the vent valve (6) supplies air at the specified air volume.

2. The method for heat preservation of hot blast stove during blast furnace overhaul according to claim 1, characterized in that, The first butterfly valve (7) and the second butterfly valve (10) are both model Z41T-10.

3. The method for heat preservation of hot blast stove during blast furnace overhaul according to claim 1, characterized in that, During the blast furnace overhaul, the hot blast stove (3) is kept warm by repeatedly cycling through "burning the furnace → shutting down the furnace → blowing air → shutting down the furnace", and the furnace is not blew when it is burning, and not burning when it is blowing air.

4. A method for heat preservation of a hot blast stove during a blast furnace overhaul according to claim 1, characterized in that, During the firing process of the hot blast stove (3), the control of the gas volume and air volume is as follows: instantaneous gas volume ≯ 15000m 3 / h, total daily gas consumption ≤270,000 m³ 3 Instantaneous air volume is 9900–11000 m³. 3 / h; the number of times the hot blast stove (3) is burned per day shall not exceed 3 times, and the burning time for each time shall not exceed 2 hours.

5. A method for heat preservation of a hot blast stove during a blast furnace overhaul according to claim 4, characterized in that, The control of gas volume and air volume during the firing process of the hot blast stove (3) is as follows: instantaneous gas volume = 15000 m³ / h 3 / h, instantaneous air volume = 10000m³ 3 / h.

6. A method for heat preservation of a hot blast stove during a blast furnace overhaul according to any one of claims 1-5, characterized in that, When supplying air, the air pressure should be ≤5kPa.

7. A method for heat preservation of hot blast stove during blast furnace overhaul according to claim 1, characterized in that, The diameter of the air supply duct (5) is Φ300.

8. A method for heat preservation of hot blast stove during blast furnace overhaul according to claim 1, characterized in that, A hot air duct (13) is installed in the hot air furnace (3). An upward flared mouth (14) is installed at the upper end of the hot air duct (13). Insulation cotton is wrapped around the hot air duct (13). When the hot air furnace (3) is venting and supplying air, the backflow shut-off valve of the backflow shut-off duct is closed, and the hot air is discharged through the hot air duct (13).

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