JPH06347361A - Fracture sensing method for stave pipe of blast furnace - Google Patents

Abstract

PURPOSE:To detect fracture of a pipe by gas sensing by connecting a gas collector and a CO gas sensor to each system of a stave pipe, lowering coolant pressure under a predetermined condition of a stave temperature, and mixing gas in a furnace from a fractured part into water. CONSTITUTION:A stave 2 is divided, for example, into four zones in the circumferential direction, and each zone has four series of cooling pipes. Coolant is raised from a tank 3 to an upper header by a pump 4, and sequentially fed from a stave H via a throttle valve 5, a flowmeter 6 through staves T, B1-B3, S1-S5 in each system to cool the stave 2. The coolant is returned from a switching valve 7 of a drain side of the stave S5 through a set header 8, a return tube 9, a cooler 10 or a set header 12, a fracture sensing line 11 to the tank 3. Gas collectors 13, 14 are coupled to the headers 8, 12, and coupled to a fracture sensor 17 for sensing CO through sampling lines 15, 16. In this case, coolant pressure is lowered under predetermined condition of transition of the stave temperature at each system, and gas is absorbed into water from a pipe fracture to sense CO.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting breakage of a pipe of a stave cooler inserted between a shell and a side wall brick in order to extend the life of the furnace side wall brick of a blast furnace and protect the side wall.

[0002]

2. Description of the Related Art A blast furnace stave cooler is made by casting a water cooling pipe called a stave between a shell and a side wall brick, and normally water (pure water) is naturally or forcedly circulated in the water cooling pipe. It is then cooled. In the stave cooler, the part exposed to high heat inside the furnace after a long period of use is missing due to high-temperature oxidation, or is gradually worn due to contact with the raw material in the furnace, and the cast water cooling pipe is exposed and damaged. Reach Further, the water-cooled pipe may undergo fatigue fracture due to the repeated deformation of the stave due to the heat load in the furnace. The place where the water cooling pipe of the stave is likely to be damaged by repeated heat load in the furnace is generally from the lower part of the shaft to the upper part of the Bosch part (however, there are some blast furnaces with a slightly different range depending on the furnace characteristics of each company).

When the water cooling pipe of the stave is broken, the water pressure is usually higher than the pressure inside the furnace, so that water leaks into the furnace, and the condition of the furnace deteriorates due to cooling. Also, due to the leakage of cooling water into the furnace, the stave cannot be cooled, the stave is severely worn and the stave itself disappears, the heat load is directly applied to the iron shell, and cracks are generated due to local overheating of the iron shell ( Hot spots). For this reason, during operation of the blast furnace, pay attention to changes in H ₂ (water decomposes into H ₂ and 0 ₂ ) in the generated gas, and if H ₂ tends to increase, workers will perform stave breakage detection work. ing.

As a method for detecting damage to the water cooling pipe of the stave, the water pressure of the cooling water is lowered to mix the gas in the furnace into the cooling water, and the mixed gas in the furnace is collected in the detection pipe of the cooling water system and collected. Then, a method is known in which an operator detects the CO concentration. Further, an apparatus in which a water channel for detecting a damaged position having a position detecting function higher than the position of the atmosphere opening valve of the cooling system is provided in the bottom water supply pipe of the normal cooling system (Japanese Patent Laid-Open No. Sho 49-49).
-65305 gazette), a bypass flow path having a gas collector is inserted in parallel in a stave cooling circulation channel system, and a stave breakage is detected by gas detection means provided on the upper part of the gas collector. JP-A-57-125337), a drainage pipe located outside the furnace body of the blast furnace cooling body is provided with a gas collector communicating with the drainage pipe, and electrical connection and disconnection in the gas collector are performed. A method of detecting and issuing an alarm as damage to the cooling body when electrical interruption occurs (Japanese Patent Laid-Open No. 1-2200)
No. 5) has been proposed.

[0005]

The method of detecting the CO concentration by the worker is a heavy-duty work of wearing an air cylinder under a CO gas atmosphere and high temperature and high humidity, and avoids the worker. Has been done. In addition, the conventional method of lowering the water pressure of cooling water and mixing the gas in the furnace into the cooling water is to mix the gas in the furnace into the cooling water while reducing the total cooling water amount to about 80% to secure the cooling water amount of the stave. Therefore, in the Bosch stave region where the water pressure is higher than the in-furnace pressure, the water pressure exceeds the in-reactor pressure, there is a pressure balance that does not mix the in-reactor gas into the water, and the detection range is limited to the shaft stave. .

Furthermore, the device disclosed in Japanese Patent Laid-Open No. 49-65305 detects a damaged position of a damaged stave detected by another method, not a damage of the stave. Further, the methods disclosed in JP-A-57-125337 and JP-A-1-222005 detect electrical continuity and disconnection in the gas collector to detect breakage of the stave, and a small amount of gas. However, there is a problem in detection accuracy.

An object of the present invention is to provide a detection method capable of detecting damage to a stave by reducing the cooling water pressure not only in the shaft stave region but also in the Bosch stave region below the furnace pressure, without significantly reducing the cooling capacity of the stave. To provide.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted earnest examinations to achieve the above object. As a result, the stave cooling water circulation system is separated into multiple series, and the cooling pipes of each series are cast in the stave. Even if one cooling pipe is damaged, the stave cooling is performed by the cooling pipes of the remaining series. Focusing on the fact that it can be done without any trouble, if a gas collector is connected to each system of the divided stave pipes and a CO gas detector is connected via a sampling line, one series unit In that case, the cooling water amount can be set to the normal level of 20 without deteriorating the cooling capacity of the stave extremely.
%, And not only in the shaft stave area,
The pressure of the cooling water in the Bosch stave area can be made lower than the pressure in the furnace, and the gas in the furnace is mixed from the damaged part of the stave pipe,
The present invention has been achieved by investigating that the accuracy of stave damage detection can be greatly improved.

That is, according to the present invention, a CO gas detector is connected via a sampling line to a gas collector provided in a cooling water circulation path of a blast furnace cooling stave cooler, and CO in the furnace gas mixed in the cooling water is connected. In the method of detecting the damage of a stave pipe by measuring the concentration, a gas collector is connected to each system of the divided stave pipes and a CO gas detector is connected via a sampling line to operate the blast furnace. For each system of the stave pipe divided into the inside, under the condition that the stave temperature is below a predetermined value and the transition of the stave temperature is parallel or downward, lower the cooling water pressure than the furnace pressure and damage the stave pipe. The method for detecting breakage of a blast furnace stave pipe is characterized in that the gas in the furnace is mixed into water to detect CO.

[0010]

In the present invention, the stave pipes divided during the operation of the blast furnace are connected to the gas collectors which can be switched for each series of the divided stave pipes and the CO gas detectors via the sampling line. For each system, under the condition that the stave temperature is below a predetermined value and the transition of the stave temperature is in parallel or is declining, lower the cooling water pressure than the furnace pressure and put the furnace gas into the water from the damaged part of the stave pipe. Since CO detection is performed by mixing it, the cooling water amount can be reduced to 20% of the normal amount for each series without adversely affecting the staves due to temperature rise, and not only the shaft stave area but also the Bosch stave area can be cooled. The water pressure can be made lower than the in-furnace pressure, and if the stave pipe is damaged, the in-reactor gas is mixed into the water, and the CO concentration can be accurately detected.

In the present invention, a gas collector is connected to each series of divided stave pipes and a CO gas detector is connected through a sampling line, because each series of divided stave pipes is connected. This is because CO detection is performed in units. Further, the condition for lowering the cooling water pressure below the furnace pressure is that the stave temperature is below a predetermined value and the transition of the stave temperature is parallel or slightly downward when the stave temperature is below a predetermined value, for example, below 340 ° C. If there is water out of one of the multiple stave cooling pipes,
This is because it was confirmed by the heat transfer analysis by the finite element method (FEM) that the back surface temperature of the stave can be maintained at 400 ° C. or lower at which the occurrence of oxidation deficiency of the stave and thermal deformation do not remain. Further, the reason why the transition of the stave temperature is parallel or slightly downward is that if the transition of the stave temperature tends to rise, the back temperature of the stave may reach 400 ° C. where thermal deformation remains.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to FIGS. FIG. 1 is a system diagram of a stave pipe breakage detecting device for carrying out the method of the present invention.
Is a graph showing the relationship between the blast furnace pressure, the cooling water pressure and the furnace position, and FIG. 3 is a graph showing the relationship between the overall heat transfer coefficient of the inner surface of the stave pipe and the stave cooling capacity. In FIG. 1, 1 is a blast furnace iron shell, 2 is a stave provided inside the iron shell 1, and is a Bosch stave consisting of a hearth stave H, a tuyere stave T, and B _{1 to} B _{3 in} order from the bottom and S.
_It consists of a shaft stave consisting of _{1 to} S ₅ . The stave 2 is divided into four zones in the circumferential direction of the blast furnace, and each stave 2 is cast with four series of cooling pipes.
Cooling water is supplied to the cooling pipes in 4 zones across the blast furnace.
It is divided into 4 series = 16 series.

The cooling water to the cooling pipe of the stave 2 temporarily rises from the dedicated circulation tank 3 to the upper header by the circulation pump 4, and is passed through the automatic throttle valve 5 and the flow meter 6 for each series (16 series). From the bottom hearth stave H to the upper tuyere stave T, Bosch stave B ₁ ~
B ₃ is supplied to the shaft staves S _{1 to} S ₅ to cool the staves 2. 7 is a drainage automatic switching valve provided in the drain side of each series of the uppermost shaft stave S ₅ (16 series),
Each drainage automatic switching valve 7 is cooled by the cooler 10 by the stave cooling water return pipe 9 connected to the collective header 8 and then returned to the circulation tank 3. 11 is each drainage automatic switching valve 7
A stave breakage detection line having a collection header 12 connected to the circulation tank 3 is connected. Gas collectors 13 and 14 are connected to the collective headers 8 and 12, and are connected to a stave breakage detection device 17 having a CO detection unit via sampling lines 15 and 16 and separated by the collective headers 8 and 12. Gas collector 13 or 14
It is configured to detect breakage of the stave 2 by CO detection of the sampling gas collected by the sampling lines 15 and 16 and sucked from the sampling lines 15 and 16.

Reference numeral 18 is a water supply pressure gauge provided for each series on the inlet side of the bottom hearth stave H, 19 is a gas detection tube provided on the outlet side of each stave 2, and 20, 21, 22, 23 are Bosch staves. B ₃ , stave thermometers provided on the shaft staves S _{1 to} S ₃ , 24 and 25 are cooling water pressure gauges provided on four series connecting pipes of Bosch staves B ₁ and B ₂ and shaft staves S ₄ and S ₅ , Reference numerals 26, 27, and 28 are in-furnace pressure gauges. 29 is a comprehensive monitoring operation device for detecting damage to the stave, 3
0 is a drainage thermometer. The stave breakage detection comprehensive monitoring operation device 29 includes a flow meter 6, a feed water pressure gauge 18, stave thermometers 20, 21, 22, 23 and a furnace pressure gauge 26, 2.
Water supply amount, water supply pressure, stave temperature, and furnace pressure of each series are input from 7, 28. In addition, the stave breakage detection comprehensive monitoring operation device 29 includes the stave breakage detection device 17
A stave breakage detection command is output to and a stave breakage detection signal is input from the stave breakage detection device 17. Further, the stave breakage detection comprehensive monitoring operation device 29 is
The automatic throttle valve 5 and the drainage automatic switching valve 7 of each series are automatically operated.

With the above configuration, when there is a suspicion of damage to the stave pipe, the stave breakage detection comprehensive monitoring operation device 29 is continuously input from the stave thermometers 20, 21, 22, 23 of the four zones. The stave temperature is searched for, and the stave temperature is 340 ° C. or less, and the stave temperature changes in parallel or in a downward trend.
Zone, and switch the drainage automatic switching valve 7 to the stave breakage detection line 11 for each series unit of the selected zone,
Cooling water pressure gauges 24, 25 and furnace pressure gauges 26, 27,
While monitoring the cooling water pressure and the in-furnace pressure input from 28, the automatic throttle valve 5 on the feed side of the switched series is operated to gradually reduce the amount of water to reduce the pressure of the cooling water. In this case, the cooling water pressure input from the cooling water pressure gauges 24, 25 is replaced with the comparison graph shown in FIG. 2 from the in-reactor pressure input from the in-reactor pressure gauges 26, 27, 28.
Adjust so that the shaft and Bosch parts are lowered as shown by C. Further, the stave breakage detection comprehensive monitoring operation device 29 confirms to what extent the cooling water flow rate input from the flow meter 6 of the relevant series has actually decreased. As shown in FIG. 3, if the amount of cooling water is reduced, the overall heat transfer coefficient of the inner surface of the cooling pipe is 200 Kcal which is normal.
/ M ² h ° becomes closer to the zero direction, the cooling capacity is extremely lowered and the stave temperature rises. If this is repeated, the oxidation loss of the stave 2 and thermal ratchet deformation progress, and the stave life becomes short.

Stave breakage detection comprehensive monitoring operation device 29
Is the stave breakage detection device 17 when the above conditions are satisfied.
The stave breakage detection command is output to. When the stave breakage detection command is input, the stave breakage detection device 17 sucks the gas collected through the sampling line 16 from the gas collector 14 provided in the collective header 12 of the stave breakage detection line 11, The CO concentration in the gas is measured to detect the presence or absence of breakage of the stave pipe, and output to the stave breakage detection comprehensive monitoring operation device 29. Further, the stave breakage detection comprehensive monitoring operation device 29 lowers the flow rate of the cooling water more than necessary so that the drainage temperature input from the drainage thermometer 30 of each series does not become a boiling state, and the allowable temperature of the stave breakage detection device 17 is increased. The opening degree of the automatic throttle valve 5 is controlled so that the drainage temperature does not rise above. If the above operation is sequentially switched to another series and repeated, damage to the stave can be reliably detected. If there is a damaged stave pipe in the middle of the system, the stave itself can be separated from the cooling system of the main stave and set as a separate system so that the main detection can be carried out without any trouble.

Further, in the present invention, when the CO detection is completed, in order to remove the influence of the gas remaining in the pipes of the sampling lines 15 and 16 in the next step, a certain amount of nitrogen gas is flowed at the end of sampling, The gas remaining in the sampling lines 15 and 16 is purged out of the system. The residual gas including the gas in the furnace in the gas collector 8 and the sampling line is discharged. After a lapse of a predetermined time, that is, after a lapse of a predetermined time from the start of gas sampling, the suction pump is stopped and the next sampling operation is started.

In order to detect breakage of the stave pipes of all series, the gas collected from the gas collector 14 provided in the collecting header 8 of the stave cooling water return pipe 9 is sucked through the sampling line 16 to extract the gas in the gas. Can be performed by measuring the CO concentration of the stave pipe and detecting the presence or absence of damage to the stave pipe.

[0019]

As described above, according to the method of the present invention, the damage detection target range of the blast furnace stave pipe can be expanded to the entire range where there is a possibility of stave damage,
It is possible to detect stave breakage accurately at an early stage and greatly contribute to the stability of blast furnace operation.

[Brief description of drawings]

FIG. 1 is a system diagram of a stave pipe breakage detecting device for carrying out the method of the present invention.

FIG. 2 is a graph showing a relationship among a blast furnace pressure, a cooling water pressure, and a furnace position.

FIG. 3 is a graph showing the relationship between the overall heat transfer coefficient of the inner surface of the stave pipe and the stave cooling capacity.

[Explanation of symbols]

 1 iron skin 2 stave 3 circulation tank 4 circulation pump 5 automatic throttle valve 6 flow meter 7 drainage automatic switching valve 8, 12 collective header 9 stave cooling water return pipe 10 cooler 11 stave breakage detection line 13, 14 gas collector 15, 16 Sampling line 17 Stave breakage detector 18 Water pressure gauge 19 Gas detector tube 20, 21, 22, 23 Stave thermometer 24, 25 Cooling water pressure gauge 26, 27, 28 Furnace pressure gauge 29 Stave breakage comprehensive monitoring and operating device 30 drainage thermometer

Claims (1)

[Claims] 1. A CO gas detector is connected via a sampling line to a gas collector provided in the cooling water circulation path of a blast furnace cooling stave cooler to measure the CO concentration in the furnace gas mixed in the cooling water. In the method of detecting breakage of a stave pipe, a gas collector connected to each system of the divided stave pipe is provided, and a CO gas detector is connected through a sampling line to divide the stave pipe during operation. For each system of the stave pipe, under the condition that the stave temperature is below a predetermined value and the transition of the stave temperature is parallel or downward, lower the cooling water pressure than the furnace pressure to remove the gas in the furnace from the damaged part of the stave pipe. A method for detecting breakage of a blast furnace stave pipe, which comprises mixing CO in water to detect CO.