EP0911418B1 - Procede et dispositif de traitement thermique par jet de gaz - Google Patents

Procede et dispositif de traitement thermique par jet de gaz Download PDF

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Publication number
EP0911418B1
EP0911418B1 EP98907225A EP98907225A EP0911418B1 EP 0911418 B1 EP0911418 B1 EP 0911418B1 EP 98907225 A EP98907225 A EP 98907225A EP 98907225 A EP98907225 A EP 98907225A EP 0911418 B1 EP0911418 B1 EP 0911418B1
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EP
European Patent Office
Prior art keywords
gas
steel strip
nozzle
blowing
heat treatment
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EP98907225A
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German (de)
English (en)
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EP0911418A4 (fr
EP0911418A1 (fr
Inventor
Hirohisa Nippon Steel Corporation KAWAMURA
Norichika Nippon Steel Corporation NAGIRA
Mutsuo Nippon Steel Corporation SHIRAGA
Jyunichi Nippon Steel Corporation HAYASHI
Yoshihiro Nippon Steel Corporation SERIZAWA
Masanori Nippon Steel Corporation SHIMADA
Kouichi Nippon Steel Corporation 46-59 WAKI
Hisamoto Nippon Steel Corporation WAKABAYASHI
Keiji Nippon Steel Corporation 46-59 OOGUSHI
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Nippon Steel Corp
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Nippon Steel Corp
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Publication of EP0911418A4 publication Critical patent/EP0911418A4/fr
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
    • C21D9/54—Furnaces for treating strips or wire
    • C21D9/56—Continuous furnaces for strip or wire
    • C21D9/573—Continuous furnaces for strip or wire with cooling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/56—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering characterised by the quenching agents
    • C21D1/613—Gases; Liquefied or solidified normally gaseous material
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/62—Quenching devices
    • C21D1/667—Quenching devices for spray quenching
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
    • C21D9/54—Furnaces for treating strips or wire
    • C21D9/56—Continuous furnaces for strip or wire

Definitions

  • the present invention relates to a heat treatment method and device for heating, cooling or drying a steel strip by blowing a jet of gas onto the steel strip.
  • a heac treatment device for heating or cooling a steel strip by blowing a jet of gas onto the steel strip.
  • gas is used as a thermal medium for conducting heat transfer in a conventional heac treatment device, the heat transfer coefficient ⁇ is low. Therefore, a sufficiently high performance can not be necessarily provided by the conventional heat treatment device, so that a demand for a high heating or cooling rate, which must be accomplished from the viewpoint of metallurgy, can not be satisfied.
  • the present inventors have proposed a cooling device for cooling a steel strip by blowing a jet of gas onto the steel strip, which is disclosed in Japanese Examined Patent Publication No. 2-16375.
  • the heat transfer coefficient is in a region of ⁇ ⁇ 400 kcal/m 2 Hr°C. In the case where the heat transfer coefficient is in the above region, it is possible to attain a cooling rate of 100°C/sec when the thickness of the steel strip is 0.6 mm. However, when thickness of the steel strip is 1.0 mm, only a cooling rate of 63°C/sec can be actually attained.
  • a roll cooling method in which a water-cooled roll is made to come into solid contact wich a steel strip, or alternatively a gas-water cooling method is used, in which gas and water are mixed with each other and a steel strip is cooled by the mixture.
  • the above roll cooling method is disadvantageous in that the roll comes into solid contact with the steel strip. Therefore, it is difficult to make the water-cooled roll come into contact with the steel strip uniformly. Therefore, the steel strip can not be cooled uniformly, which causes a deterioration in a profile of the steel strip.
  • the gas-water cooling method is disadvantageous in that a surface of the steel strip is oxidized by dissolved oxygen contained in water because water is used for cooling in this method. Therefore, when the above gas-water cooling method is used, it becomes necessary to conduct acid cleaning again on the strip after the completion of heat treatment.
  • the heat transfer coefficient in the heat treatment device for heating or cooling a steel strip by blowing a jec of gas onto the steel strip it is preferable to increase the flow velocity of gas blown onto the steel strip.
  • the heat transfer coefficient can be enhanced substantially in proportion to an increase in the flow velocity of gas blown onto the strip.
  • a pressure loss in the piping is sharply increased, and it becomes necessary to provide a very large capacity of blower in order to obtain a predetermined heat transfer coefficient.
  • An object of the present invention is to reduce the amount of power required for a heat treatment device for conducting heat treatment on a steel strip by blowing a jet of gas onto the steel strip while the heating rate or cooling rate is maintained high.
  • the heat treatment device for conducting heat treatment on a steel strip by blowing a jet of gas onto the steel strip of the present invention is characterized as described in the following items (1) to (3).
  • Fig. 1 shows a range of the experiment made in the present invention and a range of the experiment made in Japanese Examined Patent Publication No. 2-16375. It can be seen in Fig.
  • Japanese Unexamined Utility Model Publication No. 61-40155 discloses a structure in which a baffle plate 3 or a spiral line 6 is arranged in the nozzle 1 so as to facilitate a turbulent flow.
  • the nozzle length must be long so that two or three baffle plates can be arranged in the nozzle. Therefore, it is difficult to industrially manufacture a large number of nozzles having such a structure.
  • gas is agitated and emitted by a centrifugal force. Therefore, this structure is not effective.
  • the intensity of turbulence is low at the center of gas flow. Accordingly, in order to enhance the heat transfer coefficient effectively, it is necessary to increase an intensity of turbulence at the center of gas flow.
  • the present inventors proposed a structure in which a baffle body 2 or a baffle plate 3 is arranged at the center of the forward end of the nozzle 1 as shown in Fig. 2. Due to the above structure of the nozzle 1, as shown in Figs.
  • the cross-section of the baffle body 2 is not limited to a circle, but the cross-section of the baffle body 2 may be formed into a polygon or other shape.
  • the present inventors made investigation into a method of discharging exhaust gas emitted from the nozzle.
  • a flow velocity of gas blown onto a steel strip may be increased.
  • a quantity of gas blown onto the steel strip may be increased.
  • gas once blown onto the steel strip remains on a surface of the steel strip and interferes with new gas blown onto the steel strip.
  • the heat transfer coefficient cannot be greatly enhanced.
  • a solid line expresses an example in which gas discharge is conducted in a good condition
  • a dotted line expresses an example in which gas discharge is not conducted in a good condition.
  • Fig. 12 shows a relation between opening portion area S 1 and nozzle opening area S 2 .
  • an opening portion 10 between the gas blowing headers 8 as shown in Fig. 13(b).
  • the rising current flows into this opening portion 10. Consequently, the jet of gas emitted from the nozzle 1 reaches a surface of the steel strip while it is seldom affected by the rising current of gas which has turned back. Therefore, the steel strip can be effectively cooled or heated. Since no gas remains between the steel strip 7 and the gas blowing header 8, gas can flow smoothly along the steel strip 7. Therefore, deterioration of the cooling or heating capacity of gas can be mitigated.
  • FIG. 15 An example of the structure of the nozzle periphery of the heat treatment device of the present invention is shown in Fig. 15.
  • the nozzle 1 is a protruding nozzle, the forward end of which protrudes more than the forward end portion of the gas blowing header 8. Therefore, when gas is discharged from the opening portion 10, a portion of the jet of gas emitted from the nozzle 1 is prevented from being directly exhausted without colliding with the steel strip.
  • Fig. 15(a) the nozzle 1 is a protruding nozzle, the forward end of which protrudes more than the forward end portion of the gas blowing header 8. Therefore, when gas is discharged from the opening portion 10, a portion of the jet of gas emitted from the nozzle 1 is prevented from being directly exhausted without colliding with the steel strip.
  • the second gas exhausting method by which gas can be exhausted smoothly will be explained below.
  • gas is released to the rear of the nozzles through the opening portion between the gas blowing headers.
  • the first gas exhausting method is disadvantageous in that the gas blowing header is divided into a plurality of portions by the space of the opening portion. For the above reasons, the equipment cost is raised although the first gas exhausting method is ideal. Therefore, according to the second gas exhausting method, the opening portion communicated with the rear side of the nozzle is eliminated, and the nozzle is protruded by an appropriate protruding height. That is, when the nozzle protruding height h shown in Fig.
  • the distance Z from the steel strip to the forward end of the nozzle is defined to be a value noc more than 70 mm
  • nozzle protruding length h is defined to be a value not less than (100 - Z) mm.
  • the above values are determined on the assumption that an estimated region of the heat transfer coefficient is ⁇ ⁇ 400 kcal/m 2 Hr°C.
  • the present inventors made an experiment in which the nozzle protruding height h was changed and a heated steel strip was cooled, so that the relationship between the density of quantity of gas and the ratio of the heat transfer coefficient was found.
  • the ratio of the heat transfer coefficient was defined as a ratio of the heat transfer coefficient when a heat transfer coefficient was determined to be a reference value. This relation is shown in Fig. 18. According to Fig. 18, when the nozzle protruding height h is 200 mm, the ratio of the heat transfer coefficient is increased substantially in proportional to an increase in the density of a quantity of gas.
  • the present inventors made investigation into a ratio of the effective gas blowing length.
  • the cooling rate is defined as ⁇ t/T°C/sec, wherein a cooling temperature difference is ⁇ t°C and a period of time required for cooling is T sec.
  • the heating rate is defined in the same manner as that of the cooling rate. From the metallurgical viewpoint, the cooling and the heating rate are important. In order to enhance the cooling and the heating rate, the present inventors devised the equipment.
  • the support rolls 16, 17 were made to come into contact with the steel strip 7 at a certain interval as shown in Fig. 19, so that the warp and flutter of the steel strip could be corrected and an interval between the nozzle 1 and the steel strip 7 could be reduced.
  • these support rolls 16, 17 are provided with roll supporting devices 18, 19 so that these support rolls 16, 17 can be advanced and retracted in operation. Due to the foregoing, it is necessary to provide support roll insertion spaces in the device, and it is impossible to blow gas into these spaces, that is, the support roll insertion spaces become a useless region from the viewpoint of heat treatment. Due to the existence of these spaces, the heating and the cooling rate are partially lowered, which is disadvantageous from the metallurgical viewpoint. It is important to increase an average heating rate or an average cooling rate in metallurgy. In order to increase these values, it is effective to enhance the efficiency of the gas blowing space, and it is also effective to reduce the support roll insertion space as much as possible.
  • an effective gas blowing length ratio is defined as a ratio of the length in which gas is actually blown out, to the length L1 from the start to the end of blowing gas.
  • the effective cooling length ratio was approximately 80%.
  • the support roll insertion space shown in Fig. 19 is divided into two sides. One is a side onto which the roll is inserted, and the other is a side which is opposed to the steel strip wherein no roll is arranged on this side.
  • the support roll insertion region which was conventionally a useless region with respect to heating or cooling, can be made very small, and even in the roll insertion region, heating or cooling can be conducted. Due to the foregoing, it becomes possible to enhance the average heating or cooling rate.
  • the present inventors made investigation into the optimization of blowing gas temperature in the case of cooling a steel strip.
  • the power required for a blower is decreased when the blowing gas temperature is decreased.
  • the blowing gas temperature is decreased to a value lower than a predetermined value, in order to decrease the blowing gas temperature, a difference in temperature, between the refrigerant used in the heat exchanger and the blowing gas is reduced. Therefore, although a pressure loss in the heat exchanger is increased, the temperature of blowing gas is not decreased so much. As a result, power required for the blower is on the contrary, increased.
  • the present inventors made investigation into the blowing gas temperature in detail. As a result, they found the following.
  • the most appropriate blowing gas temperature that is, a point at which power required for the blower becomes smallest was approximately in a range from 60°C to 200°C.
  • the present inventors also found that this point fluctuated in accordance with the heat transfer coefficient, the steel strip temperature on the entry side of the heat treatment device, the steel strip temperature on the delivery side of the heat treatment device, and the temperature of refrigerant used in the heat exchanger.
  • the present inventors also made detailed investigation into a region in which the heat transfer coefficient is high. As a result of the investigation, the following were found.
  • the present inventors made investigation into a method by which the blowing gas temperature can be effectively decreased.
  • a heat exchanger in which water is used as refrigerant is commonly used as a cooling method for cooling gas.
  • the heat exchanger is conventionally arranged on the entry side of the blower. In this case, in order to decrease the blowing gas temperature, the capacity of the heat exchanger may be increased.
  • the heat exchanging efficiency is deteriorated and a pressure loss is increased when gas flows in the heat exchanger.
  • the blowing gas temperature is not decreased.
  • the blowing gas temperature is decreased too much, the power required for the blower is, on the contrary, increased. Therefore, the present inventors aimed at an increase in temperature of blowing gas in the case of increasing the pressure of blowing gas by the blower.
  • the present inventors devised an arrangement in which the heat exchanger is arranged on the delivery side of the blower. That is, instead of installing more heat exchangers on the entry side of the blower, more heat exchangers are installed on the delivery side of the blower.
  • the characteristic of the nozzle, to the forward end of which the above baffle body was attached, was investigated when a plate at high temperature was cooled with this nozzle. The result of the investigation is shown in Fig. 4.
  • the heat transfer coefficient was enhanced at a position immediately below the nozzle center as shown in Fig. 4.
  • a ratio of the projection area of the baffle body to the cross-section of the nozzle under the above cooling condition is shown in Fig. 5.
  • the effect of enhancing the heat transfer coefficient can be provided when the ratio of the projection area of the baffle body to the cross-section of the nozzle is not lower than 3%.
  • the ratio of the projection area of the baffle body to the cross-section of the nozzle is not lower than 12%, a pressure loss at the forward end of the nozzle caused by installing the baffle body is increased. Therefore, the amount of power required for the blower is increased. Therefore, an arrangement in which the ratio of the projection area of the baffle body to the cross-section of the nozzle is not lower than 12% is not economical.
  • the ratio of the projection area of the baffle body to the cross-seccion of the nozzle was determined to be 3 to 12%.
  • the thickness of the baffle plate is smaller than 3%.
  • FIG. 9 is a cross-sectional view of the heat treatment device of the present invention.
  • nozzles 1 which are protruded being opposed to the steel strip 7 running in the direction of an arrow. Jets of gas are blown out from the nozzles 1 onto the steel strip 7 so that the steel strip 7 can be heat-treated.
  • this heat treatment device is used as a heating device when the blowing gas is heated, and this heat treatment device is used as a cooling device when the blowing gas is cooled.
  • the heat treatment chamber 12 is filled with non-oxidizing atmosphere, in which hydrogen is mixed with nitrogen.
  • non-oxidizing atmosphere in which hydrogen is mixed with nitrogen.
  • a gas such as air
  • the arrows shown in Fig. 9 represent currents of gas.
  • Gas is continuously supplied from the blower 9. Then, gas is sent to the divided gas blowing headers 3 via a gas distribution header (not shown). A jet of gas, which has been emitted from each nozzle 1 and has collided with the steel strip 7, takes heat away from the steel strip 7. Then, the jet of gas is turned back and exhausted from the opening portion 10. That is, gas is exhausted to the rear side of the nozzle 1 with respect to the steel strip 7. After gas has been exhausted, it is sent to the blower 9 again via the suction gas header 11. The pressure of gas is increased by the blower 9, and then it is recycled.
  • a device for heating or cooling gas is arranged before or after the blower 9.
  • only gas which has passed through the opening portion 10 via the suction gas header 11 is circulated again, however, it is possible to suck gas from a portion of the heat treatment chamber without providing the suction gas header 11.
  • a jet of gas emitted from each nozzle 1 collides with the steel strip 7, and then it passes through the opening portion only under the force of a rising current formed by a jet of gas which has been turned back.
  • the cross-section of the gas blowing header 8 is rectangular.
  • the cross-section of the gas blowing header 8 may be circular, elliptical or polygonal, or, alternatively, the cross-section of the gas blowing header 8 may be a combined shape.
  • Fig. 10 is a view showing an arrangement of the nozzles 1 and the gas blowing headers 3, wherein this view is taken on the side of the steel strip.
  • the nozzles 1 may be arranged in a zigzag manner.
  • sets of nozzles 1 may be arranged, in a zigzag manner, wherein each sec of nozzles 1 is composed of 3 to 7 rows of nozzles 1.
  • a steel strip 7 the thickness of which was 1.0 mm, was cooled by blowing a jet of gas wherein a mixed gas of nitrogen and hydrogen was used as a refrigerant.
  • the cooling nozzle protruding length h was set at 20 mm.
  • Fig. 12 there is shown a heat transfer coefficient ratio when a ratio of the area of the opening portion to the area of the nozzle opening was changed under the condition of a constant blower power.
  • Table 1 the nozzle diameter, the nozzle pitch and others are shown.
  • a cooling capacity for cooling the steel strip is evaluated by the average heat transfer coefficient in the width direction of the steel strip.
  • the result of a comparative example is shown at the points where ratios of the area of the opening portion to the area of the nozzle opening are 0, 3.4 and 17.3. In this case, when the ratio of the area is 0, all the opening portions are closed.
  • the result of the example is shown in a range from the point where the ratio of the area of the opening portion to the area of the nozzle opening is 5.8, to the point where the ratio of the area of the opening portion to the area of the nozzle opening is 15.7. In a range from the point where the ratio is 5, to the point where the ratio is 17, the ratio of the heat transfer coefficient of the example is higher than that of the comparative example.
  • the protruding length h of the nozzle 1 is not more than 5 times of the inner diameter D of the nozzle 1.
  • the reason is that the heat transfer coefficient is remarkably lowered, as shown in Fig. 16, when the protruding length h of the nozzle 1 exceeds 5 times of the inner diameter D of the nozzle.
  • the reason why the heat transfer coefficient is remarkably lowered is thought to be that, when the nozzle protruding length h is large, the flow velocity of gas is decreased until a rising current of gas reaches the opening portion 10 between the gas blowing headers 8 when the nozzle protruding length h is large, so that it becomes difficult for gas to be exhausted.
  • FIG. 17 An example is shown in which gas is exhausted while the opening portion of the gas blowing header is eliminated and the nozzle protruding height h is set at an appropriate value.
  • This example is shown in Fig. 17.
  • the gas blowing header 8 is formed into a box-shaped gas blowing header in which a certain number of nozzles are arranged.
  • distance Z is set at a value not more than 70 mm.
  • a current 14 of gas After a jet of gas has been emitted from the nozzle 1, it collides with the steel strip 7. Then the jet of gas flows along the steel strip 7. In a short time, the jet of gas collides with a jet of gas emitted from an adjacent nozzle. Therefore, the jet of gas flows in a direction opposite to the direction of the jet of gas emitted from the nozzle, that is, the jet of gas flows from the steel strip 1 toward the gas blowing header 8. After that, this jet of gas collides with the gas blowing header and flows along the gas blowing header. In a short time, this jet of gas passes through a region interposed between the gas blowing header 8 and the steel strip 7 and is exhausted outside.
  • the gas blowing header when the height h of the nozzle is determined to be not lower than a predetermined value, gas can be smoothly discharged, however, the gas blowing header may be appropriately divided so that spaces can be formed between the divided gas blowing headers and gas can be discharged through the spaces. Especially when the width of the steel strip is large or the length of the gas blowing header is large in the longitudinal direction, that is, when the size of the gas blowing header is large, it is effective to divide the gas blowing header.
  • FIG. 19 is a view showing a conventional heat treatment device for conducting heat treatment by blowing a jet of gas.
  • the steel strip 7 and the nozzle 1 are made to be close to each other in this arrangement so that the efficiency of a jet of gas can be enhanced.
  • the steel strip is alternately pressed by the left support roll 16 and the right support roll 17. However, no gas is blown into the left support roll insertion space 23 and the right support roll insertion space 24.
  • Fig. 20 an example of the present invention will be explained below.
  • an extension 22 of the gas blowing device on the opposite side to the support roll with respect to the steel strip 7. Due to the above arrangement, length L2 from the starting position to the ending position of gas blowing was shortened.
  • the actual gas blowing length shown in Fig. 19 is the same as the actual gas blowing length shown in Fig. 20, however, when length L1 is compared with length L2, length L2 is shorter than length L1, that is, the ratio of the effective gas blowing length was enhanced. In this case, a period of time required for heating or cooling was shortened by (Ll - L2)/V seconds, wherein a moving speed of the steel strip 7 is V m/sec.
  • the heating or the cooling rate it is possible to increase the heating or the cooling rate in accordance with that.
  • the ratio of the effective gas blowing length was increased from 82% to 90%.
  • the heating or the cooling capacity can be enhanced, so that the heating or the cooling rate can be further increased.
  • the heat treatment device in which the support rolls are directly contacted with a steel strip so as to conduct heating or cooling, since it is generally difficult to make the rollers come into contact with the steel strip uniformly, the heat treatment device is disadvantageous in that the temperature of the steel strip becomes nonuniform.
  • the diameters of the support rolls are usually not more than 300 mm ⁇ , that is, diameters of the support rolls are usually small.
  • a surface pressure of the support roll is higher than that of a commonly used heating or cooling roll, the diameter of which is 1000 mm ⁇ , wherein the surface pressure is defined as a pressure by which the steel strip is pressed against the roll. Therefore, it was found that no problems were caused with respect to nonuniform temperature in the case of heating or cooling.
  • Fig. 21 is a cross-sectional view showing the right support roll portion.
  • the structure of the left support roll portion is substantially the same as that of the right support roll portion. Therefore, only the right support roll is explained here.
  • the support roll is a water-cooled roll.
  • the right support roll 17 is arranged between both side walls of the heat treatment chamber wall 13 and rotatably supported by bearings 26 which can be slid on the side walls in the longitudinal direction.
  • the gas blowing headers and the nozzles are arranged in a clearance on the left of the steel strip 7, however, they are omitted in the drawing for simplification.
  • a bearing 29 arranged on the opposite side has a rotary joint structure, and a water feed pipe 28 and a drain pipe 29 are connected with the rotary joint.
  • the bearing 26 is arranged in such a manner that it can slide. Therefore, the bearing 26 can be advanced and retracted by a motor for moving the support roll via a power transmission shaft 31 and a distributor 32.
  • cooling water can be supplied to the right support roll 17 via the water supply pipe 28, and waste water is discharged outside through the drain pipe 29.
  • the support roll is used as a cooling roll, however, when heated fluid is used, it is possible to use the support roll as a heating roll. Even in the case of cooling, it is possible to use fluid other than water. Further, in the case of heating, instead of using fluid, electric power may be supplied to the roll, so that the roll can be used as an electrically heated roll. It is possible to control a heating or cooling capacity by controlling a temperature or quantity of fluid to be supplied or by controlling an electric current to be supplied to the roll.
  • FIG. 22(a) is a view showing a conventional example of the heat treatment device in which a non-oxidizing gas is circulated and a jet of non-oxidizing gas is blown onto a steel strip so that the steel strip can be cooled.
  • reference numeral 7 is a steel strip which is an object to be cooled. The steel strip 7 is cooled in non-oxidizing gas (not shown) inside the heat treatment chamber wall 13.
  • Reference numeral 9 is a blower for sucking and blowing the non-oxidizing gas in the heat treatment chamber. This blower 9 sucks gas from the heat treatment chamber via a duct 34.
  • this duct 34 In the middle of this duct 34, there is provided a heat exchanger 35 for cooling gas, and the thus cooled gas is boosted by the blower 9. The thus boosted gas is introduced again into the heat treatment chamber via the duct 34 and blown onto the steel strip 7 via the gas blowing header 8 and the nozzle 1. Therefore, the steel strip 7 can be quickly cooled.
  • the flow velocity at the nozzle end is not high. Accordingly, a high boosting pressure is not required for the blower, and the increase in the gas temperature is small in the blower. For the above reasons, no problems are caused in practical use.
  • the heat transfer coefficient is raised in the cooling of a steel strip, it becomes necessary to increase the flow velocity at the nozzle end, and a high boosting pressure is required for the blower. For the above reasons, an increase in temperature caused in the process of boosting can not be neglected.
  • the cooling efficiency can be enhanced when the heat exchanger 35 is also arranged after the blower 9 as shown in Fig. 22(b), that is, the cooling efficiency can be enhanced when the heat exchanger 35 is also arranged on the downstream side of the blower 9.
  • a capacity of the heat exchanger in the arrangement shown in Fig. 22(b) can be made smaller than that of the heat exchanger in the arrangement shown in Fig. 22 (a) .
  • a pressure loss in the heat exchanger is reduced, and a capacity of the blower can be made smaller.
  • the heat exchangers are arranged before and after the blower. However, if no problems are caused in the blower from the viewpoint of heat resistance, the heat exchanger arranged on the upstream side may be removed, and the heat exchanger may be arranged only on the downstream side.
  • the heat treatment device for heating, cooling or drying a steel strip by blowing a jet of gas onto the steel strip
  • the heat treatment device for heating, cooling or drying a steel strip by blowing a jet of gas onto the steel strip the length of useless running sections in the insertion spaces of the right and the left rolls can be shortened, that is, length of sections not contributing to heating, cooling or drying a steel strip can be shortened. Therefore, the total length of the heat treatment device can be reduced. Due to the foregoing, it is possible to reduce a period of time for heating, cooling or drying a steel strip, so that the heating rate, cooling rate or drying rate for heating, cooling or drying a steel strip can be enhanced. Further, the heat exchanger for cooling gas is arranged on the delivery side of a gas compressor such as a blower. Due to the foregoing, it becomes possible to effectively lower the temperature of blowing gas. As a result, the cooling efficiency can be enhanced, and power required for a gas compressor such as a blower can be reduced.
  • the apparatus can be made compact and an intensity of power of the blower can be made greatly smaller than that of the blower of the conventional arrangement. Accordingly, from the viewpoint of reducing the running cost, it is possible to provide a great merit.
  • cooling is conducted without causing problems of nonuniform temperature of a steel strip, and also without causing deterioration of a profile of the steel strip and oxidation of a surface of the steel strip caused in the process of cooling with gas and water, which are caused in the roll cooling of the conventional cooling system in which the heat transfer coefficient is ⁇ ⁇ 400 kcal/m 2 Hr°C. Therefore, it is possible to enhance the quality of the steel strip, and it is unnecessary to provide an acid cleaning device for removing an oxide film. Therefore, the apparatus can be simplified.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Strip Materials And Filament Materials (AREA)
  • Heat Treatments In General, Especially Conveying And Cooling (AREA)

Claims (4)

  1. Procédé de réalisation de traitement thermique sur une bande d'acier en soufflant un jet de gaz sur la bande d'acier depuis une buse (1) qui dépasse verticalement d'une surface plane d'une embase (8) jusqu'à une hauteur h depuis ladite surface, dans lequel l'ouverture de sortie de la buse (1) se trouve à une distance z de la bande d'acier allant jusqu'à 70 mm, afin de chauffer, refroidir ou sécher la bande d'acier (7), caractérisé en ce qu'une inégalité de W/4 ≤h est satisfaite, dans lequel W est une quantité de gaz (densité de quantité de gaz) soufflé sur une unité de zone en m3/min • m2 et h est en mm.
  2. Dispositif de traitement thermique destiné à effectuer le procédé selon la revendication 1, dans lequel un espace d'insertion pour rouleau (23, 24), dans lequel des rouleaux de support (16, 17) sont agencés en alternance à intervalles réguliers le long de la direction de progression de la bande d'acier (7), est prévu dans un espace de soufflage de gaz (25) dans lequel sont agencées les buses (1) destinées à souffler des jets de gaz, de manière à empêcher la bande d'acier (7) de voleter ; et des buses destinées à souffler des jets de gaz sont agencées dans l'espace d'insertion pour rouleau sur le côté opposé au côté d'insertion pour rouleau par rapport à la bande d'acier (7) de manière à étendre l'espace de soufflage de gaz (25).
  3. Dispositif de traitement thermique selon la revendication 2, dans lequel les rouleaux de support (16, 17) sont refroidis en cas de refroidissement de la bande d'acier (7) ; et les rouleaux de support (16, 17) sont chauffés en cas de chauffage ou séchage de la bande d'acier (7).
  4. Dispositif de traitement thermique selon l'une quelconque des revendications 2 ou 3, dans lequel un échangeur thermique (35) destiné à refroidir le gaz est agencé au moins sur le côté en aval d'un compresseur à gaz tel qu'une soufflante (9).
EP98907225A 1997-03-14 1998-03-13 Procede et dispositif de traitement thermique par jet de gaz Expired - Lifetime EP0911418B1 (fr)

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Application Number Priority Date Filing Date Title
JP82247/97 1997-03-14
JP8224797 1997-03-14
JP16664497 1997-06-10
JP166644/97 1997-06-10
JP17781597 1997-06-19
JP177815/97 1997-06-19
PCT/JP1998/001072 WO1998041661A1 (fr) 1997-03-14 1998-03-13 Dispositif de traitement thermique par jet de gaz

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EP0911418A1 EP0911418A1 (fr) 1999-04-28
EP0911418A4 EP0911418A4 (fr) 2004-03-24
EP0911418B1 true EP0911418B1 (fr) 2006-02-08

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KR (1) KR100293139B1 (fr)
CN (1) CN1083896C (fr)
BR (1) BR9804782A (fr)
DE (1) DE69833424T2 (fr)
TW (1) TW404982B (fr)
WO (1) WO1998041661A1 (fr)

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CN111363910B (zh) * 2020-03-03 2021-11-19 首钢京唐钢铁联合有限责任公司 一种脉冲式烧嘴加热输出控制方法及系统
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BR9804782A (pt) 1999-08-17
EP0911418A4 (fr) 2004-03-24
CN1083896C (zh) 2002-05-01
DE69833424D1 (de) 2006-04-20
KR100293139B1 (ko) 2001-06-15
EP0911418A1 (fr) 1999-04-28
CN1219206A (zh) 1999-06-09
WO1998041661A1 (fr) 1998-09-24
DE69833424T2 (de) 2006-10-26
TW404982B (en) 2000-09-11
KR20000011032A (ko) 2000-02-25

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