JPS6254033A - Continuous annealing installation for steel strip - Google Patents

Abstract

PURPOSE:To provide a continuous annealing installation which heats a steel strip efficiently in a non-oxidizing state by disposing plural heating burners which can form non-equil. region having an intermediate reaction product of combustion and having no free O2 in flames to the outlet side region of a direct firing heating zone. CONSTITUTION:The reduction type heating burners which can form the above- mentioned non-equil. regions in the flames are used on the outlet side of the direct firing heating zone (a) and the flames are made to collide against the steel strip S in the non-equil. regions to heat the steel strip. The steel strip S after heating is sent in the non-oxidizing state to a holding zone (b) where the steel strip is held in a reducing atmosphere. The steel strip is subjected to cooling essentially consisting of cooling by cooling rolls 8 in a cooling zone (c) in succession thereof. An ordinary overaging treatment zone (e) is provided to the rear of the cooling zone and after the steel strip S is emitted from the final cooling zone behind said treating zone (e), the steel strip is subjected to rolling by a temper rolling mill (f). The steel strip is efficiently and continuously annealed by this invention without forming oxide films, etc., on the steel strip and while the simplification and reduced energy economization of the installation are attained.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to continuous annealing equipment for steel strip.

[Prior Art] As a heating power type of a continuous annealing furnace, an indirect heating method using a radiant tube and a direct heating method are known.

Of these, the latter direct heating method has superior heating ability compared to the indirect heating method, and has the advantage of being able to burn out the cold rolling oil, so cleaning equipment for it can be omitted.

Widely used in hot-dip galvanizing lines and continuous annealing lines for electrical steel sheets.

However, with the conventional direct flame heating method, the steel strip is easily oxidized,
There is a big problem with this, which is that if you use a locked roll, it will cause a kua tsubu. In contrast to the conventional direct fire heating method, the so-called non-oxidizing direct fire heating method was developed in the Special Publication No. 5B-4.
No. 4133, Japanese Patent Publication No. 59-29651, etc. have proposed this method for use in continuous heat treatment equipment for cold rolled steel strips. This method reduces the air ratio in each combustion control zone (1, 4
In this method, heating is performed while suppressing oxidation of the steel strip using a method such as less than 0.6).

However, although this method claims to be non-oxidizing, it is actually a weak oxidizing method, and there are oxidizing scum even in the combustion generated scum with an air ratio of less than 1.0 (:02. Because of this, the oxide film thickness after heating is 50A° of the original plate.
Therefore, if this method is used in continuous annealing equipment, hydrogen must be concentrated at a high concentration (approximately 20%) in the soaking zone following the heating zone.
There is no choice but to adopt a method such as reducing the hydrogen as a gas, or setting up a treatment zone called a strong reduction zone on the outlet side of the direct flame heating zone and reducing with hydrogen at a concentration of 1:1 (approximately 50% or more).

In addition, recent continuous annealing equipment tends to be larger in order to reduce manufacturing costs, but in such equipment, if the direct-fired heating zone is configured with one bath as described above, the furnace height will be high. This may cause the steel strip to fluctuate or the furnace pressure: t
++There is a problem that causes difficulty in control, and for this reason, 2
There is no choice but to make a pass or a more complex pass.

However, in such a multiple-pass direct-fire heating zone, roll pickup occurs in the rolls in the heating furnace, and as a result, the surface quality of the steel strip is significantly impaired. In order to prevent roll pickup with such furnace rolls, for example, an isolation chamber is provided to accommodate the furnace rolls as shown in Japanese Patent Application Laid-Open No. 53-54100, and a protective atmosphere is created inside this isolation chamber. Such complicated measures must be taken. Furthermore, even if such a roll protection method is adopted, it is very difficult to properly connect the roll isolation chamber to the inside of the direct-fired furnace under high-temperature conditions such as in a direct-fired heating furnace, and it is difficult to properly connect the roll isolation chamber to the inside of the direct-fired furnace. In order to achieve SD #1, it is necessary to supply a huge amount of J-holding atmosphere gas of 11:1, which is not practical.

[F-stage for solving the problem] The present inventor conducted extensive studies in view of such conventional problems, and as a result, the non-NV-equilibrium region in the flame, that is, combustion intermediate products (intermediate ion , radicals, etc.) exist/+'
(11) A heating burner that can form a region where free oxygen does not exist is extremely effective in non-oxidizing heating of steel strips, and by placing it in the heating zone under predetermined conditions, it is possible to heat steel strips in a non-oxidizing and reducing state. I found out. The present invention applies such a reduction type heating burner to a direct-fired heating zone, and further combines such a heating zone with a cooling zone using a specific cooling method, thereby eliminating problems caused by oxidation 11Q etc. of the steel strip. The aim of the present invention is to provide equipment that can efficiently perform continuous combustion without any problems, while simplifying the equipment and saving energy.

That is, in the first invention of the present application, a cold JJI zone that includes a direct-fired heating zone, a soaking zone, and a roll cooling zone is sunk in order from the input side, and a temper rolling mill is arranged on the output side of the final processing zone. . Its basic feature is the arrangement of a plurality of heating burners capable of forming non-equilibrium regions in the flame, which do not have free oxygen.

Further, the second invention of the present application is characterized in that an e-tropic is provided in front of the above-mentioned open-fire heating zone, and the third invention of the present application is characterized in that an e-tropic is provided in front of the open-fire heating zone. It is characterized by having the following.

[Function] In the direct-fired heating zone of the present invention, a non-equilibrium region in the flame, that is, a region where combustion intermediate products often exist and free oxygen does not exist (non-equilibrium region), is formed in the heating burner. is used. In such a heating burner, combustion in the flame is completed - f' L/ CO2, H2 (], N2゜11□
, the region containing CO, etc., i.e., the quasi-to-equivalent region, is oxidizing, whereas the region containing intermediate ions, radicals, etc., is oxidizing.
The Jl-to-equilibrium region exhibits reducing properties, and by colliding with the steel strip in this non-V-equilibrium region, the steel strip can be heated in a reduced state.

In the continuous combustion equipment of the present invention, the steel strip is heated in a direct heating zone, and in this heating zone, it is reductively heated by a reduction type heating burner disposed at least in the outlet area, so that the steel strip is kept in a non-oxidized state. Sent out to soaking zone.

In this direct-fired heating zone, rolling oil adhering to the surface of the steel strip is burned and removed while heating. In the subsequent soaking zone, the steel strip is soaked in a reducing atmosphere, but since the steel strip is sent into this soaking zone in an almost non-oxidized state, the atmosphere is weakly reducing (H2: 3~ 10%) is sufficient.

A cooling roll is installed in the following cooling zone, and the roll cooling is
The body is cooled down. An overaging treatment zone is usually provided at the rear of the cooling zone, and after the steel strip exits the final cooling zone at the rear of this timely treatment zone, it is subjected to terra bowl rolling in a temper rolling mill. In this type of equipment, a heating zone is provided using a target fire, and non-oxidation heating is possible in this heating zone. As a result, the H2 concentration in the subsequent soaking zone can be kept extremely low, and furthermore, the roll cooling allows the temperature to be lowered to over-aging temperature. Since the steel strip is rapidly cooled in the process, there is no need for +1F heating for overaging treatment, resulting in a significantly reduced operation compared to conventional continuous annealing furnaces. In addition, due to the non-oxidizing heating and cooling method using water-cooled rolls, the steel strip is coated with an oxide film, making pickling equipment completely unnecessary. Furthermore, since it uses a direct flame heating method with excellent heat load response and a water-cooled roll method with easy adjustment of the cooling cycle, it is possible to accurately change the heat cycle according to the material and desired material, and continuously. Cycle-free annealing, that is, substantially enables processing operations regardless of furnace temperature, sheet J, sheet width, etc. II).

In addition, in the second invention of the present application, a r-tropic is provided in front of the direct-fired heating zone, and the steel strip is heated in this p-tropic by exhaust gas introduced from a direct-fired heating furnace or the like, and then heated by the direct-fired heating zone. Taken to the tropics. In continuous heating annealing, the heating time is short, so the heating time effect is small, and the heating temperature is set relatively high compared to batch annealing. The equipment equipped with this equipment is operated for the purpose of high-speed annealing, so the heating temperature is higher than 11.
There is a strong tendency to set Therefore, by performing r-heating of the steel strip in such continuous annealing treatment of the steel strip,
The load for heating in the direct flame heating zone is reduced, and appropriate high temperature and high speed annealing becomes possible.

In addition, even if the surface of the steel strip is oxidized to some extent due to r-heat, it is equipped with a direct heating zone that can reduce this oxidation, so it heats up to a high temperature of 250 to 500 degrees Celsius in the preheating zone and removes the rolling oil that has adhered to the surface of the steel strip. It can be removed by combustion, and in combination with the removal of rolling oil in the direct heating zone, good burn-off properties can be achieved.

In addition, since the heating rate in the heating zone using the direct heating method is high, the heating temperature (final heating temperature) tends to be higher than that using the indirect heating method, which requires extra energy. 57. by preheating the steel strip. The advantage is that the temperature gradient is lowered and the heating temperature does not need to be increased twice.

Furthermore, in the third invention of the present application, cleaning equipment for the surface of the steel strip is further provided on the +1f side of the tropical zone 1-f, and in this cleaning equipment, iron powder adhering to the surface of the steel strip is removed. Rolling oil and iron powder (1D, etc.) are usually attached to the surface of the steel strip after cold rolling. As mentioned above, the rolling oil is burned and removed in the direct heating zone and preheating zone, but the iron powder is not removed and may accumulate in the furnace or circulate in the furnace together with the furnace atmosphere scum. Trapped between steel strips,
It may cause scratches on the product surface. In the present invention, such iron powder is removed by the cleaning equipment. Furthermore, when continuously annealing high-Si, P, Mn, Ti, Cr, etc. steel strips, these produce oxide films that are difficult to reduce.
The air ratio of the combustion gas may be lowered to reduce oxidation caused by heat and direct heating (heating before reductive heating). In this case, the burn-off properties of the rolling oil on the surface of the steel strip in tropical or direct-fired heating zones will be slightly reduced, or the poor burn-off properties will be compensated for by the lack of leaning, resulting in proper rolling. Provides oil removal effect.

"Embodiment" Figures 1 and 2 show an embodiment of the present invention. ! Direct fire heating zone (a), soaking zone (b), cooling zone (C), overaging treatment zone (d), and final cooling zone (e) are provided in order from 1, and the output of this final cooling zone (e) is A temin pallet (f) is disposed at n-1 with an outlet louver (g) interposed therebetween.

``In the two-leg open-fire heating zone (a), a reduction type heating burner is provided at least in the outlet area, and thereby,
Even if the surface of the steel strip is oxidized by a non-reducing heating burner (generally used diffusion burner) in the heating zone (l-1), it is converted to 5 yen and sent to the soaking furnace that continues in a non-oxidized state. Although it is possible to install a five-pronged heating burner over the entire effective heating length of the heating zone, this type of burner is far less efficient than the conventional non-reducing heating burner. Heat damage: 1 ton is small, and in order to ensure the necessary rapid heating, it is necessary to place burners closely together.For this reason, it is preferable to place reduction heating burners within the minimum necessary range. I can't believe it.

When the direct-fired heating zone (a) consists of multiple passes as in this embodiment, the five-type heating burner described in I- is
From the il area, physically, at least the output (!) of each path.
- It is preferable to arrange it in the path 1 area including the heating area of the 1st sheet roll straight IWf. In the case of a direct-fired heating furnace that consists of multiple passes, as mentioned above, the oxidation of the steel strip causes the problem of roll pickup in the roll itself in the furnace. In order to send the steel strip to the soaking zone (b) in this condition, it is necessary to arrange a reduction type heating burner in the outlet area of each pass, bring the steel strip into contact with the threading roll in a non-oxidized state, and send it out of the furnace. ·stomach.

FIG. 4 shows the structure of such an open-fire heating zone. In the figure, (I) is the first bus, (II) is the second pass, (9a) to (9d) are the passing rolls in the furnace, and (S) is the steel strip. In such a configuration, a heating burner group including a plurality of reduction-type heating burners (10) described above in the line direction is provided in the straight-curved heating area of the outlet passing rolls (9b) and (9d) of the rice bowl bus. (X) is placed. On the other hand, a heating burner 1 (Y), which is a non-reducing heating burner that is commonly used in the past, is arranged in the heat area for the crosspiece.

Figure 8 shows the first pass (I) in such an open flame heating zone.
The graph shows the changes in oxide film thickness and steel strip temperature at In the side region (reduction heating region), the oxidation thickness of the original plate base is reduced to approximately 5p! :The second one that continues in the oxidized state
It can be seen that it is being sent out to bus (II).

Figures 6 and 7 show an example of a reduction type burner, and this heating burner has a cylindrical edge burner tile (1
) are provided with a plurality of combustion air discharge holes (2) at right intervals in the circumferential direction on the inner wall (6) of the burner, and a fuel gas discharge hole (3) is provided in the inner center of the burner. (2) and the fuel gas discharge hole (3) have the following configuration.

b) An angle θ of 60” or more is attached to the air supply direction of the air discharge hole (2) with respect to the tangent to the inner circumference of the burner tile.

1iIN for the burner axial direction of the fuel gas discharge hole (3) and air discharge hole (2), when the fuel gas discharge hole is closer to the burner tile outlet 11 than the air outlet (=), and vice versa. When is (+), -0.1D to +0.25D (D
:L1 diameter inside the burner).

c) The distance from the air discharge hole (2) to the burner tile outlet [1 (5)] is 0.6D to 3D.

When the heating burner configured in this manner is used at an air ratio of 1.0 or less, an unbalanced region is formed in the flame within a predetermined range. That is, in such a heating burner, rapid combustion is realized by the swirling flow of combustion air from the air discharge hole (2) and the fuel gas discharged from the center of the burner, and 1 ( So,
A region containing combustion intermediate products in a number i+k and containing no unreacted free oxygen, that is, a non-equilibrium region is formed. Figure 10 shows an example of measurement using an ion detection probe in the non-V, equilibrium region in the flame formed by such a heating burner. Once upon a time, the amount of combustion intermediate products was 4 in i+L? It means being present.

According to this, the burner outlet 11 is provided with i'
A non-P-equilibrium region is formed, and outside of this is a quasi-P-equilibrium region containing 02.820, N2, etc. even though the reaction has almost completed.

Figure 11 shows the five-component heating characteristics of such a heating burner, that is, the limit temperature that can be heated without oxidation (the limit temperature for Nishitoshi Steel's thin plate).
．． It has been shown that the steel strip can be heated up to about 900° C. in the range of 95°C.

Furthermore, in the present invention, in addition to the heating burner described above, for example, a so-called radiant cup burner can be used. In order to perform a rapid combustion reaction, this burner rapidly burns a -t mixture of air and fuel gas in the four hemispherical parts of the burner tile, increasing the temperature of the inner surface of the burner tile and reducing radiant heat transfer by 11%. ．． It has the characteristic that a high heat flux can be obtained when the temperature of the heated object is in the 71 range of i temperature. And with this burner, the air ratio is 1
．． By avoiding combustion at temperatures below zero, an unbalanced region is formed in the flame.

However, since this radiant burner uses a t-mixing method of combustion air and fuel residue, it is not possible to preheat the combustion air, and since it can only heat the air, non-oxidation heating is limited to about 750℃. However, there are drawbacks such as inapplicability to cases where heating in a higher temperature range is required. In this regard, the heating burner shown in Fig. 6 can use hot air, so it is possible to heat up to about 900°C without oxidation, and by using hot air in this way, the flame temperature can be increased. Therefore, compared to a radiant burner, the reducing action itself caused by intermediate reaction products can be effectively reversed.

In the direct flame heating zone, the above-mentioned pupil type heating burner is used, as shown in Fig. 4, the flame is approximately perpendicular to the steel strip (S), and moreover, in the non-balanced region, it hits the steel strip surface. arranged to collide. Heating burners used in conventional direct-fired heating furnaces, such as NOF, are not formed in a shape that clearly distinguishes between the non-P-equilibrium region and other regions, as in the case of a burner. Therefore, if a visible flame comes into direct contact with the steel strip, the surface of the steel strip will be severely oxidized. Generally speaking, in order to prevent the flame from touching the steel strip directly, the flame should be aligned with the width direction of the steel strip.
arranged to form rows. In contrast, in the present invention, the steel strip is heated by a non-equilibrium region formed in the middle in the longitudinal direction of the burner flame. The burners are arranged so that they collide in a non-equilibrium region.

The soaking zone (b) following the direct heating zone (a) uses an indirect heating method using a radiant duplex, and is basically the same as a conventional soaking zone. However, in the continuous annealing furnace of the present invention, the direct heating zone (a) has a reducing ability and the steel strip is sent to the soaking zone (b) in an unoxidized state, so the steel strip is not oxidized in this soaking zone. Atmosphere of degree, that is, H2: 3-10%,
Usually, an atmosphere of about 4 to 6% is sufficient.

By setting the contact length of the roll (8) to the steel strip (S) to be I+T, the cooling end point temperature can be adjusted to #1.

In addition, the temper mill (f) has a hard 7' [
Preferably, chrome roll is used. Such rolls include Japanese Patent Application No. 60-41009 and Japanese Patent Application No. 60-41.
A roll such as that shown in No. 011 is particularly interesting. This roll is less likely to cause indentation flaws due to the edges of the steel strip, and therefore can appropriately prevent flaws on the surface of the steel strip due to roll flaws, and improve roughness of the steel strip. It is also possible to maintain a print rate of 100%, which enables cycle-free continuous annealing of the steel strip width. In other words, in the past, edge marks and roll flaws such as those shown in
, +259, the steel strips to be processed should be connected one after another to form a cap shape, or the steel strips to be processed should be made of hard chrome rolls that do not cause scratches, as shown in L, to overcome such constraints. This means that the continuous annealing operation that connects steel strips regardless of their width or width becomes 1' + 100 mm.

Figure 2 shows another embodiment of the present invention, in which an open heating zone (a), a heating zone (a), a heating zone (h) (2 baths) on a
is provided. In this r tropics (h) there is an open heating zone (
a) or a soaking zone (b) or its combustion exhaust gas is introduced;
Steel strip (S) 0) 'f-heating is to be carried out. According to the studies of the present inventors, the oxidation of steel and steel is governed by the thermal temperature and the air ratio when the combustion exhaust gas used is generated; By using combustion exhaust gas with a different temperature, it is possible to heat the steel strip with almost no oxidation. is 1.0 when using combustion exhaust gas generated at an air ratio of 1.0 or more and heating the steel strip to 280°C or more.
It has been found that by using combustion exhaust gas produced at an air ratio of less than , it is possible to efficiently heat the steel strip in a non-oxidizing state, regardless of the heating temperature.

In this way, in the tropics (h), depending on the regulation of the air ratio of the combustion scum, there is no oxidation (r) heat or (n) function, or in the present invention, the subsequent direct flame heating zone (a) has a reduction effect on the oxide film. Therefore, a certain degree of oxidation in the f tropics (h) is allowed, resulting in a temperature of about 50°C as shown by the dashed line (a) in Figure 9.
It is possible to increase the heat permissible temperature of degree P, and as a result, even with an air ratio of 1.0 culm degree, preheating of about 400℃ becomes 1 t.
Tropical heat (h) can be used to burn and remove rolling oil from the surface of the steel strip.

Figure 3 shows another uninvented embodiment, with tropical (h)
) is provided with cleaning equipment (i) whose main purpose is to remove iron powder via an inlet looper (j). Since this cleaning equipment (i) is designed to remove iron powder like LLJ, a simple equipment is sufficient. Figure 5 shows the leaning equipment like this. - For example, (11) is an alkaline bath, (12) is a scrubber (Brasilol Shin, (
13) is the back-up roll, (14) is a hot water spray nozzle, (15) is a hot water rinse pot, and (16) is a dryer, and these cleaning equipment can remove iron powder in 1 minute. I can do it.

Table 1 shows the continuous annealing equipment of the present invention as described above (Fig.
FIG. 3) shows an embodiment according to FIG. In addition, positive, 7
This is a comparative example of a conventional NOF furnace-bengen furnace with one roll cooling. As is clear from the comparison with such comparative examples,
It can be seen that according to the continuous annealing equipment of the present invention, the generation of oxidized particles is significantly suppressed compared to the conventional NOF method, and a product with excellent chemical conversion treatability etc. can be obtained. It has also been shown that since the cooling rate can be changed arbitrarily by roll cooling in the cooling zone, it is possible to manufacture products with holes from the same material in a continuous manner.

As the temper rolling mill of the present invention, a temper mill with a tensicon leveler can be used, or a temper mill and a tensicon leveler can be used together.

It is also possible to provide a plating device such as galvanizing after cooling the rolls.

The fuel gas nozzle (7) is a fuel gas nozzle protruding from the heating burner shown in FIGS. 6 and 7, and in this embodiment, the fuel gas discharge holes (
3) is formed.

In such a heating burner, its air discharge hole (2)
The reason why the air supply angle θ is set is to create a swirling flow in the combustion air within the burner tile.This swirling flow forms a negative pressure area inside the burner, and this negative pressure recirculates the gas. As a result, combustion can be promoted and an appropriate non-equilibrium region can be formed. By setting the air supply angle θ to a maximum of 60°, preferably from 20 to 40°, a stable swirling property of the airflow can be obtained.

The burner axis of the fuel gas discharge hole (3) and the air discharge hole (2) are the same! When IN is on the (-) side, the gas temperature is high and the combustion intermediate products are highly distributed over a wide range, but on the other hand, free 02 (unreacted 02) tends to be distributed long in the axial direction. In order to appropriately form the non-equilibrium region that is the object of the present invention, it is necessary to minimize the remaining distance of this play 11102 in the burner axial direction, and its limit is determined as 10 ID.

If N is (+) (!11), a proper non-equilibrium region will be formed, but if it becomes too large, the inner end wall of the burner tile will be heated to over 1400°C, which is undesirable. The limit is +0.25D for the protection of SiC.Figure 12 shows the fuel gas discharge hole (14) and the air discharge hole (
13) We investigated the relationship between the burner axial distance from the burner outlet 121, the gas temperature in the burner tile, the 02 concentration, and the ionic strength when the burner axial direction is equal to N = -0.25D. According to this, N is like this (-)
0-1, the remaining distance B in the axial direction of the free 02
L. It has been shown that there is a large presence of

Figure 13 shows the burner axial force and natural pressure f at the fuel gas hole and air discharge hole.
iN and remaining axial distance of free 02! This shows the relationship with 11Lo, and according to this, N is 10, which is more than ID.)
As it increases toward the side, Lo increases rapidly, and for this reason, -0 and 1D are the limits on the (-) side.

On the other hand, FIG. 14 shows the relationship between the distance in the direction of burner 1 oil from burner outlet 1, 02 concentration, ion strength, and gas temperature when N is 10 and ID is assumed to be 100 and ID.

According to FIGS. 13 and 14, N is (+) f
1, there is no problem with the 0° concentration, and the burner output [1
Rain can pass through the area at a distance of 0.5D or more from
An i-area has been formed.

However, if N is increased to the (+) side, the burner tile inner end wall (4) is heated, so the relationship graph between the distance N and the temperature Tb of the burner tile inner end wall (4) in FIG. As shown in , Tb at +0.25D is 1400℃ or higher.
Therefore, considering that the material of the inner end wall is SiC, it is preferable to set the temperature to +0.25D or more in view of the heat resistance limit. From the above, regarding the burner center axis distance tsN of the combustion gas discharge hole and the air discharge hole, -〇, ID ~ 0
．． It is preferable to set it as the range of 25D.

The distance 11iL from the air discharge hole (2) to the burner tile outlet [1 (5)] has a close relationship with the formation range of the non-equilibrium region.
-I'm looking forward to it. That is, if L exceeds 3D, the non-equilibrium region will be formed only in the part immediately after the burner tile exit [I], which is not preferable. On the other hand, if L is less than 0.6D, the flame becomes a petal-shaped flame immediately after the burner tile 1-1 comes out, and an appropriate unbalanced region cannot be stably obtained around the center axis of the burner. Therefore, it is preferable to set L in the range of 0.6D to 3.0D.

When continuously heating a thin steel plate, the distance between the burner tile outlet (5) and the steel plate must be at least a certain distance (usually about 100 mm or more).
If not, there is a risk that the steel plate will come into contact with the burner during threading. Therefore, it is preferable that the unbalanced region in the flame be formed in as wide a range as possible, including the steel strip passing position located at a predetermined distance from the burner exit side.

Figure 16 shows the relationship between the distance BL and the distance L11 from the burner exit [1 to the end of the non-P balance region (the end of the anti-burner (end of jill); 1, for example, point A in Figure 14). It is one solid thing. According to this, when L exceeds 3D, the non-P-equilibrium region is formed only immediately after the exit of the burner tile [I, and is hardly formed on the surface side beyond that. As L becomes smaller, the range in which the unbalanced region is formed expands, but in the region (X) where L is less than 0.6D, the flame becomes a petal-shaped radial flame immediately after the burner tile exits.
An appropriate non-equilibrium region cannot be stably formed at the burner axis. From the above, it is desirable that the distance jllL from the air discharge hole (2) to the burner tile outlet (5) be set to range 1 of 0.6D to 3.0D.

In addition, in the structure of the heating burner as described above, if the swirling flow of the air discharged from the combustion air discharge hole (2) is too strong, the temperature of the combustion gas on the burner outlet side in the burner radial direction 11 will become insufficient. As a result, it may become difficult to form a stable and wide range of non-V equilibrium regions.

In such a case, in order to reduce the air swirling flow and make the temperature distribution uniform, the fuel gas discharge hole (3) should be
The rl radiation direction is J1 with respect to the tangent to the outer circumference of the fuel nozzle.
A swirling flow that is perpendicular to the fuel gas flow or the airflow from the combustion air discharge hole (2), that is, a swirling flow that collides with the air swirling flow from the opposite direction. The structure to be formed or the fuel waste discharge hole (3),
A structure in which the injection direction is in the burner axis direction or a direction inclined to the burner axis direction, and an inclination angle (torsion angle) in the burner opening direction with respect to the burner tile radial direction in the air discharge hole (2). It is possible to adopt a structure that imparts the following characteristics independently or in combination.

In addition, in order to expand the heating area by the burner, at least the inner wall of the burner tile (1) on the tip opening side from the combustion air discharge hole formation part is provided with a divergence angle f that increases the diameter toward the burner inner diameter 111 or the tip distance ml side.・In order to facilitate the formation of the air discharge hole (2), a swirling flow path for combustion air along the circumferential direction of the burner is provided in the wall of the cylindrical burner tile, and the swirling flow path It is also possible to adopt a structure in which a plurality of combustion air discharge holes are provided to communicate the combustion air with the inside of the burner.

[Effects of the Invention] According to the present invention described in 1-1 above, a steel strip can be heated without oxidation by a direct flame heating method, and troubles caused by oxidation of the steel strip such as roll pickup can be appropriately avoided. . In addition, the heating zone is 11 types of direct flame heating, and as a result of the non-oxidation heating in the heating zone being 11 types, the H2 concentration in the subsequent soaking zone can be kept extremely low, and furthermore, by roll cooling, it can reach the overaging temperature. Since the steel strip can be rapidly cooled, there is no need for +1T heating for overaging treatment, and for these reasons, it is possible to operate with a significant energy saving compared to conventional continuous annealing furnaces. In addition, the use of non-oxidizing heating and cooling method using water-cooled rolls prevents oxidation of the steel strip, making pickling equipment completely unnecessary. Furthermore, since it uses a direct flame heating method with excellent heat f'J load response and a water-cooled roll method that allows easy adjustment of the cooling cycle, the heat cycle can be changed accurately and responsively according to the material and desired material quality. Cycle-free continuous annealing, i.e. furnace temperature,
This has the effect of enabling processing operations regardless of plate thickness, plate width, etc.

Moreover, in addition to the above-mentioned effects, the second invention of the present application reduces the heating load in the direct flame heating zone during high-speed annealing, and ii) enables appropriate high-temperature and high-speed annealing.

In addition, in combination with a reduction type direct-fired heating furnace, a certain degree of oxidation due to heat is allowed, so the rolling oil adhering to the surface of the steel strip is burned off by preheating at a high temperature of 250 to 500 degrees Celsius in the f-tropics. This, combined with the removal of rolling oil in the direct heating zone, results in good burn-off properties.

In addition, since the heating speed in the heating zone using the direct heating method is high, the heating temperature (final heating temperature) tends to be higher than when using the indirect heating method, which requires extra energy. By heating the steel strip, the gradient of temperature rise is lowered and the heating temperature is reduced to the required amount -F.
The advantage is that you don't have to worry about it.

Furthermore, in addition to the above-mentioned effects, the third invention of the present application effectively removes iron powder adhering to the steel band, which cannot be removed by heating and combustion.
It is possible to appropriately prevent secondary troubles similar to roll pickup caused by iron powder, and it also has the effect of reinforcing the rolling oil removal effect in tropical regions and direct fire heating zones.

[Brief explanation of the drawing]

FIGS. 1 to 3 are explanatory diagrams showing embodiments of the present invention, respectively. FIG. 4 is an explanatory diagram showing an example of an open heating zone equipped with a membrane of the present invention. FIG. 5 is an explanatory diagram showing the cleaning equipment of the equipment of the present invention. 6 and 7 show an example of a reduction heating burner used in the equipment of the present invention, and FIG. 6 is a longitudinal sectional view;
FIG. 7 is a sectional view taken along the line ■-■ in FIG. Figure 8 shows the changes in oxide film thickness and steel strip temperature during the first pass of the open-fire heating zone shown in Figure 4.
This study deals with the relationship between the air ratio of combustion exhaust gas and the acid-free p-thermal limit temperature in the tropics. Figure 10 is similar to Figures 6 and 7.
This figure shows an example of a non-equilibrium region forming range in the heating burner shown in the figure. FIG. 11 similarly shows the reduction heating characteristics of the heating burner. Figures 12 to 16
The figure shows the characteristics of the heating burner shown in Figures 6 and 7, and Figure 12 shows the characteristics of the fuel scum (when the distance 1N between the discharge hole and the air discharge hole in the burner axial direction is -0.25D). The relationship between the distance from the burner outlet 11, gas temperature, 02 concentration, and ionic strength, Figure 13 shows the distance N between the fuel gas discharge hole and the air discharge hole in the burner axial direction and the remaining Jr distance in the burner axial direction of free #0□. The relationship with tli Lo, Figure 14 shows the distance fiN
The relationship between the distance fiL from the burner output [1, gas temperature 02 concentration, and ionic strength, the 15th National Electric Power Company has the relationship between the distance fiN between the fuel gas discharge hole and the air discharge hole and the burner tile rear wall temperature Tb FIG. 16 shows the relationship between the distance from the air discharge hole to the burner outlet and the distance LR to the end of the unbalanced region. In the figure, (a) is an open heating zone, (b) is a soaking zone, and (C
) is a cooling zone, (d) is an intermediate pickling facility, (e) is an overaging treatment zone, (f) is a temper mill, (h) is a tropical zone, (i) is
(8) is a cooling roll, and (10) is a quinary heating burner. 9th illustration, 10g 5il! i! Q 7Bkl:.

Claims (3)

[Claims] (1) A direct heat heating zone, a soaking zone, and a cooling zone mainly consisting of roll cooling are provided in this order from the entry side, and a temper rolling mill is placed on the exit side of the final processing zone, and A steel strip characterized in that a plurality of heating burners capable of forming a non-equilibrium region in the flame that contains combustion intermediate reaction products and does not have free oxygen is arranged at least in its outlet region. Continuous annealing equipment. (2) A preheating zone, a direct-fire heating zone, a soaking zone, and a cooling zone mainly consisting of roll cooling are provided in this order from the input side, and a temper rolling mill is placed on the exit side of the final processing zone, and A steel characterized in that the fire heating zone is provided with a plurality of heating burners capable of forming a non-equilibrium region in the flame that contains combustion intermediate reaction products and does not contain free oxygen, at least in its outlet region. Continuous annealing equipment for strips. (3) Cleaning equipment for the steel strip surface from the entry side, preheating area,
A direct-fired heating zone, a soaking zone, and a cooling zone mainly consisting of roll cooling are provided in this order, and a temper rolling mill is disposed on the exit side of the final processing zone, and the direct-fired heating zone includes at least one of the following: 1. Continuous annealing equipment for steel strip, characterized in that a plurality of heating burners capable of forming a non-equilibrium region in the flame, which contains combustion intermediate reaction products and does not contain free oxygen, is arranged in the exit region.