JPS61295310A - Method for operating blast furnace - Google Patents

Abstract

PURPOSE:To prevent the uneven decrease and descending of green ore in a blast furnace in the tuyere direction and to stabilize the operation of the furnace by providing a hot wind control valve to each tuyere pipe and increasing or decreasing the feed flow rate of wind by these control valves in the stage of blowing the high-temp. hot wind from the tuyeres into the furnace. CONSTITUTION:The circumferential levels of the ore and coke layer 4 in the furnace are measured by ore layer level sensors 5a, 5b, and are compared with the adequate level of a calculation control device 12 to monitor the condition in the furnace. The hot wind control valves 8 are controlled for each of the tuyere blast pipes 7 of the tuyere block corresponding to the ore layer 4a to decrease the feed flow rate of the wind from the tuyere 6 if the ore layer 4a is unevenly decreased and is lower than the standard level 6b. The supply rate of oxygen for combustion is thereby decreased and the melt reduction reaction rate in the ore layer 4a is decreased by which the descending speed of the charge is decreased from the other direction and the uneven decrease is restored. Longer time can be spared for melting of the iron ore by decreasing the flow rate of the wind through the tuyeres in the above-mentioned manner even in the case of the descending of the green ore, by which the descending of the green ore is eliminated.

Description

[Detailed Description of the Invention] [Industrial Application] The present invention provides a method for operating a blast furnace for iron-making, in particular, a heat-resistant hot air control valve made of ceramics or the like is provided in a tuyere branch pipe, and the hot air control valve is used to This invention relates to a method of operating a blast furnace that increases or decreases the air flow rate of the tuyere branch pipe in the tuyere, thereby preventing the furnace from slipping in the furnace and from falling raw ore in the direction of the tuyere.

[Conventional technology]

In a steelmaking blast furnace, 30 to 40 tuyeres are installed on the outer periphery of the lower part of the furnace to blow high-temperature hot air into the furnace. For example, temperature-controlled hot air with a temperature of 900 to 1300° C. and a humidity of about 7 to 50 g/Nm (maximum 60 g/Nm) is blown into the furnace. On the other hand, the raw material ore is charged to form a uniform layer through a charging bell, movable armor, etc., and reacts in the furnace with high-temperature hot air blown from the bottom of the furnace, reducing, softening, and melting. After deposition and melting, the hot metal becomes hot metal in the furnace sump and is tapped from the tap hole 10 to 12 times a day.

In the operating method of a blast furnace, problems such as poor uniformity of gas flow in the circumferential direction, adhesion of fused materials to the inner wall of the furnace and uneven gas flow, or non-uniform charging of raw materials, etc. As shown in Fig. 2, the phenomenon of ``sliding'' of the raw material charge occurs.

Furthermore, as shown in FIG. 3, the non-uniformity of the gas flow in the circumferential direction causes a so-called "green ore fall" phenomenon in which there is a large amount of unreduced ore at the tip of the tuyere.

These ``padding'' phenomena cause poor reactions in the blast furnaces and eventually cause wind outages, and the ``green ore falling'' phenomenon causes fluctuations in the S1 component in the hot metal or a drop in the temperature of the hot metal at the tap hole. A solution was requested from the standpoints of ironing, hot metal composition, and once-in-a-lifetime management.

On the other hand, conventionally, it has been difficult to control the amount of high-temperature hot air blown from each tuyere branch pipe due to the material of the control valve, and it has not been possible to control the amount of air blown from each tuyere. For this reason, in the tuyeres in the direction where the charge descending speed is high, the phenomenon of "green ore precipitation" often occurs.This is because the Si content in the pig iron or the hot metal temperature
It can be recognized from the fact that the hot metal coming out from the taphole in the direction in which the phenomenon occurs is different from the hot metal coming from other tapholes.

In other words, the above-mentioned phenomena of "sloping of the charge" and "green ore falling" are caused by the non-uniformity of the gas, so in order to solve this, the amount of air blown from the tuyere branch pipe in the circumferential direction is controlled. That was what was requested.

Conventionally, attempts have been made to use control valves made of metal valve bodies as flow rate control valves for these tuyeres, but the valve body lacks heat resistance and cannot withstand high temperatures, so water-cooling the valve body has also been adopted. However, the heat loss was large and it was not put to practical use.Although attempts were made to install water-cooled control valves or dampers in the annular high-temperature hot air pipe to control the overall air flow, Controlling the amount of air blown from each tuyere had not yet been put into practical use.

As a hot air control valve to solve these above-mentioned problems, the applicant proposed in Utility Application No. 170080/1987 that the valve plate 21 and valve stem 22 of the valve body 13 are made of ceramic material as shown in FIG. This valve body is integrated with heat-resistant members 36 and 37.
The application has been filed for a butterfly valve 8 which is housed in a casing 31 lined with a casing 31 to form a flow path.

[Problem that the invention seeks to solve]

The present invention is a blast furnace operating method that prevents the "one-sided" phenomenon of the charge and the "green ore precipitation" phenomenon at the tip of the tuyere, maintains proper and stable blast furnace operation, and prevents the occurrence of the "green ore falling" phenomenon at the tip of the tuyere. An object of the present invention is to provide an operating method for stabilizing hot metal components and hot metal temperature.

[Means for solving problems]

The present invention has been made to solve the above-mentioned problems. That is, a ceramic heat-resistant hot air control valve proposed in the above-mentioned Utility Model Application No. 170080/1980 and a further improved hot air control valve are provided for each tuyere branch pipe, and the air flow rate of each tuyere is controlled by the hot air control valve. This is a method of operating a blast furnace that prevents the phenomenon of "slippage" of the charge in the blast furnace and the phenomenon of "green ore falling" at the tip of the tuyere.

That is, the gist of the present invention is that when high-temperature hot air is blown into the furnace from the furnace siding via the tuyere branch pipes, a hot air control valve is provided for each tuyere branch pipe, and the hot air control valve controls the control of some of the tuyere branch pipes. There is a method of operating a blast furnace that increases or decreases the amount of air blown to prevent the inside of the furnace from slipping in the direction of the tuyeres and from falling raw ore.

However, the hot air control valve is a heat control valve in which (i) the valve plate of the valve body and the valve stem are integrally constructed of ceramic, and (i) the valve plate of the valve body and the valve stems provided above and below it. and a support shaft integrally formed of ceramic; and an annular ceramic valve body having an inner diameter approximately equal to the flow path of the high-temperature hot air and formed to rotatably support a lower portion of the valve body. a pair of support members, the support members being connected to the valve plate;
It is a hot air control valve that is connected from both sides of the base of the valve shaft and the support shaft and arranged in the casing, A cylindrical second heat resistant member fitted into the heat member is divided into two from the center, and these first and second heat resistant members are inserted into both sides of a valve body disposed at the center of the casing. The valve body is rotatably supported, pressing members are fitted on both sides of the first and second heat-resistant members, a stopper is attached to the outer periphery of the holding member, and the stopper is welded to the inner wall of the casing to connect them. (iv) In the hot air control valves of (i) and (iii) above, the chamber formed between the valve stem of the valve body and the seven flange of the casing is connected to the flange. It is connected to the drain discharge part through a passage provided in the drain.

These things achieve the object of the present invention. [Function] “One-sided burnout” in blast furnaces, which was difficult to control in the past.

And the branch pipe air flow rate of the tuyeres with a lot of “green ore fall” was calculated as described above (
i) to reduce the amount of combustion air supplied in the direction of the tuyere by reducing it with a hot air control valve configured from (1v),
This reduces the rate of melting and reduction reactions in this part.

As a result, the charge descending speed is lower than in other directions, and it recovers if it slips to one side.

In addition, as shown in Figure 3, the tuyere NL corresponds to “raw ore fall”.
By reducing the amount of air blown from the branch pipes L6a@ to 6a, it is possible to take sufficient time to melt the iron ore, thereby reducing the amount of ``green ore falling''.

Due to the above two effects, the charge level is made uniform in the circumferential direction, and it is also possible to prevent the phenomenon of localized "green ore falling" at the tuyeres and to recover from the one-side slippage, which was previously considered difficult. As a result, suitable blast furnace operation is maintained, and this also brings about excellent effects such as making the temperature of the hot metal at each tap hole and the Si in the hot metal constant.

As for the hot air control valve used in the blast furnace operating method of the present invention, the hot air control valve shown in FIGS. 4 to 6 in the embodiment described later has a strong valve body, a wide flow rate control range, and is easy to manufacture. This is suitable because it is easy to clean and has a drain removal mechanism.

Examples of implementation and abuse of the present invention will be described below [Example] Fig. 1 is an explanatory diagram of an embodiment of the present invention, Fig. 2 is an explanatory diagram showing the arrangement of the taphole of a blast furnace, and Fig. 3 is an explanatory diagram showing the arrangement of the tuyeres. , FIG. 4 is an explanatory diagram of the installation of the hot air control valve.

In the figure, 1 is a blast furnace, 2 is a furnace wall, 3 is a charging bell, 4 is an ore and coke layer, 4a is an ore layer, 5 is an ore layer level sensor, 6 is a tuyere, 7 is a blowing tuyere branch pipe, 8 1 is a hot air control valve, 9 is an annular hot air pipe, 10 is a tap hole, 11 is a sump section, 12 is a calculation control device, and 18 is a raw ore downfall section.

In order to react the ore charged into the blast furnace 1 through the charging bell 3 and the coke layer 4, high-temperature hot air of 900 to 1300°C and absolute humidity of 7 to 50 g/Xi is passed through the annular hot air pipe 9.
The air is blown from the tuyere 6 via the air blowing branch pipe 7. The slag and pig iron that are reacted and generated in the furnace form a slag layer and a pig iron layer in the sump 11 at the bottom of the furnace, and are periodically discharged from the tap hole 10 to the tap hole (not shown) to the large gutter. be done.

In this example, there are four tap holes (inner diameter 50 mm), 10a, Job, 10e, and 10d, as shown in Fig. 1
A total of 4 blocks with 10 tubes (40 cabinets φ) are arranged in each block, and a total of 40 tuyeres are arranged, and a hot air control valve 8 is provided for each tuyere branch pipe.

First, in order to prevent the furnace from slipping, which is the object of the present invention, the level of the ore and coke layer 4 in the furnace in the circumferential direction is measured in advance by the ore layer level sensor 5, and the calculation control device In contrast to the appropriate level of
Monitor the condition of one side inside the furnace. If the mineral layer level of 4a is lower than the standard 4b and the tuyere block corresponding to tuyere branch pipe 7a8 of tuyere branch pipes 7a6 to 7a8 of 9a is removed as shown in FIG. By controlling the hot air control valve 8a6-8ml provided in the furnace and reducing the amount of air blown, the amount of oxygen supplied for combustion is reduced, and the melting and reduction reaction rates in the corresponding part of the furnace are reduced. The object descending speed in other directions, for example, 4b, is lowered, the one-sided slippage is recovered, and the levels of 4a and 4b are equalized.

On the other hand, the phenomenon of "green ore falling" often occurs in conjunction with the above-mentioned slipping phenomenon in the furnace, so by controlling the hot air control valve installed in each relevant tuyere branch pipe and reducing the tuyere air flow rate, Sufficient time can be given to melt the iron ore, and the phenomenon of 'green ore falling' is eliminated.

・Furthermore, the "green ore fall" phenomenon is caused by an abnormality in the temperature of the hot metal from each of the tap holes 10a to 10d, and when hot metal components such as S
The calculation control device 12 detects an abnormality in the tuyere corresponding to the tap hole 10a, for example,
m. Of these, “raw ore” is falling at the tip of the tuyere for 6m and ~6h.
The existence of the partial zone 18 is confirmed by another ore level sensor 5, a sensor for detecting raw ore fall (tuyere brightness meter), or visual observation from the tuyere viewing window, and the corresponding tuyere branch pipe 7a6~ 7al hot air control valve 86-8
a8, reduce the amount of air blown from the tuyeres 6a6 to 6a8, and adjust the melting and reduction times as described above to make the charging level 4 uniform in the circumferential direction, and to reduce the local part of the tuyeres 6as to 6a. This also eliminates the problem of "raw ore precipitation" at the tuyere.

In this case, the abnormality may be notified to the operator by an alarm device (not shown), and the corresponding hot air control valve may be controlled manually or automatically by the calculation control device 12.

By performing such an operation, it was possible to recover "one edge" and prevent "green ore falling", which had been considered difficult in the past, and proper blast furnace operation was maintained.

Furthermore, due to the reduction in the amount of "cutting" and "green ore falling" of the charge, the circumferential non-uniformity of the cohesive zone in the lower part of the blast furnace is reduced.
The variation in molten iron composition, hot metal temperature, and slag composition for each tap, that is, the tap-to-tap Siσs, decreased from 0.1% to 0.08%.

In addition, "green ore falling" to the tip of the tuyere in the direction where "one side" has conventionally occurred is more common than other tuyeres, and the impact of falling ore from the copper water-cooled small tuyere (protruding 30 to 40 cm into the furnace). However, by implementing the operating method of the present invention, the siding replacement cycle was extended from 3 months to 6 months.

Next, a hot air control valve for carrying out the method of the present invention will be described. In the present invention, the butterfly valve as shown in FIG. 8 described above has high heat resistance, and can be practically used as a hot air regulating valve 8 in the tuyere branch pipe 7.

However, the present applicant has further developed a hot air control valve in which the strength of the valve plate for opening and closing the flow path of the butterfly valve and the flow rate control range are significantly increased.

FIGS. 5 and 6 are front and side views showing a portion of the improved hot air control valve in cross section. 5 and 6, 8 is a hot air control valve, 13 is a valve body, 14 is a casing that accommodates the valve body, 15 is a drive section for the valve body 13, and 16 is a drain discharge section provided in the drive section 15. be.

In the valve body 13, 21 is a disc-shaped valve plate, and 22 is a valve plate 2.
1, the valve stem 2 is provided at the top of the valve plate 21, and 23 is the valve stem 2 provided at the bottom of the valve plate 21.
A support shaft is provided on the same line as 2, and these are integrally constructed of ceramics.

In the casing 14, 31 is a steel outer cylinder having flanges 32, 32a and 33 at both ends and the upper part, and the flange 33 has a passage opening into the chamber A formed between the flange 33 and the valve shaft 22. 34 are provided.

35.35a is a support member made of ceramics that supports the valve plate 21 from both sides of the valve plate 21 via bushings;
6.36a is a cylindrical first heat resistant member whose outer diameter matches the inner diameter of the outer cylinder 31; 37a is a cylindrical first heat resistant member whose outer diameter matches the inner diameter of the first heat resistant members 36, 36a; 36,
A cylindrical second heat-resistant member longer than 36a, 38 is a hot air flow path, 39° 39a is a cutout provided on the inner periphery of the opposing part,
40.40a is a semicircular cutout portion provided above the cutout portions 39, 39a, through which the valve stem 22 is pushed; 41.41
A is a stepped portion cut off to the end of the first #4 thermal member 36, 36a at the outer periphery of the end. 42, 42a are ring-shaped support members made of ceramics, the outer diameter of which is the same as that of the second I.
l aligned with the cutout 39.39a of the thermal member 37.37a;
The inner diameter is secondly the inner diameter of the four heat members 37, 37a, and therefore the flow path 3.
It is formed to match the diameter of 8. 43, 43a
is Bush. 44° 44a is a ring-shaped holding member made of heat-resistant material, the outer diameter of which matches the inner diameter of the outer cylinder 31, and the inner diameter of which matches the step portions 41, 41 of the second heat-resistant members 37, 37a.
L-shaped cutout portions 45, 45a are formed at the ends in alignment with a. Reference numerals 47 and 47a denote ring-shaped steel fasteners that are attached to the cutout portions of the holding members 44 and 44a via gland packings 48 and 48a, and are welded to the inner wall of the outer cylinder 31 to secure the respective parts to the outer cylinder 31. fixed inside.

In the drive unit 15, 51 is a motor, and 52 is a motor 51.
This is a cover that covers the connecting part between the output shaft and the valve shaft 22, and a flange 53 is provided at the bottom.
3 includes a passage 34 provided in the flange 33 of the casing 14.
A hole 54 communicating with the hole 54 is provided.

In the drain discharge part 16, 61 is a drain pipe whose one end is fixed to the flange 53 of the cover 52 and communicates with the hole 54; 62 is a valve provided on this pipe 54;
3 is a stem that supports the vibro 1.

In the hot air control valve configured as above, the flange 3
2, 32a connect the control valve 8 to the air flow path of the air blowing branch pipe 7 of the tuyere 6, and the valve shaft 22 is connected by the motor 51 of the drive unit 15.
By rotating the valve plate 21, the valve plate 21 rotates within the flow path 38 about the valve shaft 22 and the support shaft 23, and the flow rate of the hot air flowing through the flow path 38 can be adjusted over a wide range.

According to an embodiment, the diameter of the fluid flow path (i.e. the inner diameter of the support member)
If the outer diameter of the valve plate is 2001 m1 and the outer diameter of the valve plate is 198 cm (therefore, the gap is 1 ym), the flow rate when the valve plate is fully open is Q1, and the flow rate when it is fully closed is Q, then the ratio between the two is Q, /Q is ■ in figure 7
As shown in the figure, the flow rate ranged from about 5% to 100%, making it possible to adjust the flow rate over a very wide range. In addition, ■ in Fig. 7 represents Q, /Q, II[ when the above-mentioned gap is 5.2a+m.
This shows Q and /Q when the gap is set to 15, and shows a great effect on controlling the amount of air blown from the tuyere from the tuyere branch pipe mentioned above.

In addition, as mentioned above, this hot air control valve has a symmetrical structure in which the first and second #4 heating members are divided into two from the center, and the valve body is inserted into both sides of the valve body disposed at the center of the outer cylinder. is rotatably supported, a symmetrically structured holding member is fitted to the outer periphery of both drawing heat members, and a fastener is attached to the outer periphery of the holding member and welded to the inner wall of the outer cylinder to join them together. Since it is fixed, it is not only easy to manufacture, but also the flow path can be formed accurately.

Therefore, the gap between the valve plate and the inner wall of the flow path can be made as small as possible, and the range of adjustment of the flow rate of hot air can also be expanded.

Furthermore, this hot air control valve is provided with a drain discharge part 16 to timely discharge hot air or drain that enters the chamber formed between the flange of the casing and the valve stem, so that the hot air is solidified in the chamber. There is no risk of interference with the rotation of the valve stem, rust, etc., and deterioration of the material can be prevented.

When the hot air control valve configured as described above is applied to the blast furnace operating method of the present invention, the object can be achieved.

〔Effect of the invention〕

According to the method of operating a blast furnace of the present invention, the phenomena of "in-furnace slippage" and "green ore falling" can be solved by controlling the hot air control valve installed in the relevant blowing branch pipe and reducing the air blowing amount to the corresponding siding. By slowing down the melting and reduction reactions in the furnace,
This makes it possible to prevent the loading of raw ore from occurring locally at the tuyere and to recover from the slippage, which has been difficult in the past.

This has the excellent effect of equalizing the hot metal temperature in the circumferential direction of the furnace, that is, for each tap hole, and the hot metal components such as Si, and maintaining proper blast furnace operation.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of an embodiment of the present invention, Fig. 2 is a diagram showing the arrangement of the taphole of a blast furnace, Fig. 3 is an explanatory diagram showing the arrangement of the tuyeres, and Fig. 4 is an explanation of the installation of the hot air control valve. Figures 5 and 6 are front and side views showing partial cross sections of the hot air control valve used in the present invention, and Figure 7 shows the relationship between the gap between the flow path and the valve plate and the flow rate. The graph and FIG. 8 are cross-sectional views showing an example of a conventional high-temperature butterfly valve. In the figure, 1: blast furnace, 4: ore and coke layer, 4a:
Kataveri ore layer part, 4b: Normal ore layer part, 6: Tuyere, 7: Blowing tuyere branch pipe, 8: Hot air control valve, 9: Annular pipe, 1O: Tapping port, 12: Computation control device, 13: Valve body , 14: casing, 15. : Valve body drive part, 16: Drain discharge part, 1
8: Raw ore fall part, 21: Valve plate, 22: Valve shaft, 23: Support shaft, 31: Outer cylinder, 34: Passage, 35.35a: Support member, 36.36a: First heat resistant member, 37.37a : First heat-resistant member, 38 second flow path, 42.42a: Ring-shaped support member, 43.43a: Bush, 44.44*:
Ring-shaped holding member, 47, 47a: Ring-shaped stopper, 61: Drain drain pipe, 62: Drain drain valve. In each figure, the same reference numerals indicate the same or corresponding parts. Representative Patent Attorney Tadashi Sato Figure 3, Figure 5, Figure 6, Figure 7 - Open &('n)

Claims (1)

[Claims] When blowing high-temperature hot air into the furnace from the furnace tuyere via the tuyere branch pipe, a hot air control valve is provided for each tuyere branch pipe, and the hot air control valve increases or decreases the air flow rate of some of the tuyere branch pipes, A method of operating a blast furnace, characterized in that it prevents slipping inside the furnace and falling of raw ore in the direction of the tuyere.