JP2005226157A - Method and device for controlling furnace temperature of continuous annealing furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a device for controlling the furnace temperature of a continuous annealing furnace capable of enhancing the energy efficiency of the continuous annealing furnace and enhancing the responsiveness to the change of the furnace temperature. <P>SOLUTION: In the furnace temperature control method to control the temperature in a furnace zone of a continuous annealing furnace to a predetermined value, exhaust gas generated by a heating burner of a heating zone 3 of a continuous annealing furnace is heated by a hot gas generator 21 to adjust the sensible heat of exhaust gas, the exhaust gas and the atmospheric gas in an overaging zone 7 are heat-exchanged by a heat exchanger 23 to control the furnace temperature in the overaging zone to a predetermined value. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a furnace temperature control method and a furnace temperature control apparatus for a continuous annealing furnace, which control furnace temperature of a steel sheet in a continuous annealing furnace for steel sheets, for example, an overaging zone or a temperature adjustment zone.

  A continuous annealing furnace is used for heat treatment of steel sheets. FIG. 7 shows a schematic layout of the continuous annealing furnace, and FIG. 8 shows a schematic layout of the continuous annealing furnace of the hot dip galvanizing equipment. In FIG. 7, a steel strip 13 that has passed through a preheater (pre-tropical) 1 from a deflector roll 11 is introduced into the furnace, and heated zone 3, soaking zone 4, slow cooling by upper and lower transport rolls 12 in the furnace. Belt 5, primary cooling zone 6, overaging zone 7, secondary cooling zone 8, and tertiary cooling zone 9 are sequentially conveyed and conveyed to the next process via quenching device 10 outside the furnace. Generally, an electric heater is used as a heat source for maintaining the furnace temperature in an overaged zone.

  Further, in the hot dip galvanizing facility shown in FIG. 8, the steel strip 13 introduced into the furnace is sequentially conveyed through the heating zone 3, the soaking zone 4, the slow cooling zone 5, the quenching zone 33, and the cooling adjustment zones 34 and 35. Then, it is hot dip galvanized in a plating pot 37 through a snout 36. Generally, an electric heater is also used as a heat source for maintaining the furnace temperature in the cooling adjustment zone.

  Recently, the production trend of various types has progressed, and furnace temperatures such as overaging and cooling adjustment zones tend to vary greatly depending on the steel plate type. Since the steel plates are welded on the line entry side and are continuously passed through, the responsiveness to which the furnace temperature of these furnace zones can be increased or decreased greatly in a short time is changed with the change of the plate steel type. Required.

  In the overaging zone and the cooling adjustment zone, the purpose is generally to maintain the plate temperature, so the capacity of the electric heater is set to a capacity that can maintain the furnace temperature during normal operation. There is no capacity for heating. Therefore, when a significant increase in the furnace temperature is required due to the change in the steel plate type, the dummy material is passed through until the furnace temperature reaches the desired temperature by the sensible heat brought in by the electric heater and the dummy material. , You have to wait for the change of sheet steel grade. Therefore, in the overaging treatment described in Patent Document 1, an atmosphere gas circulation system in an overaging zone is configured, and a gas heater for heating the atmosphere gas is installed in the circulation system.

Further, as shown in the schematic layout of conventional exhaust gas utilization in FIG. 9, the exhaust gas from the radiant tube burner in the heating zone 3 is collected by the exhaust gas blower 20 through the exhaust gas pipe 14 in the plenum chamber 2 where the pressure is kept uniform. 2 is sent to the heat exchanger 16, and the heat exchanger 16 heats the preheating gas of the preheater 1 by heat exchange. The preheating gas is circulated through the preheating gas duct 17, the preheater 1, the preheating recovery exhaust gas duct 18, and the heat exchanger 16 by the preheating gas circulation blower 19. The exhaust gas passes through the exhaust gas blower 20 and is exhausted from the chimney 25 as it is.
Japanese Patent Laid-Open No. 57-11378

  In Patent Document 1, wasteful energy is required because the overaged atmosphere gas is heated using only an external heat source. In addition, in the case of electricity, there is a disadvantage that energy equivalent to the amount of heat generated by the originally required electric heater must be applied to the gas heater, which does not save energy.

  In the case of using the exhaust gas in the heating zone shown in FIG. 9 for heating the preheating gas of the preheater, the exhaust gas is effectively used because the exhaust gas is exhausted as it is from the chimney 25 after heat exchange with the preheating gas. Not.

  Further, looking at the responsiveness of the furnace temperature, from the graph showing the temperature drop pattern according to temperature and time in FIG. 5 and the graph showing the temperature rise pattern according to temperature and time in FIG. When the furnace temperature had to be lowered from, for example, 500 ° C. to 200 ° C. due to a change in the cycle, it took about 2 hours to lower the temperature. Further, in FIG. 6, when the furnace temperature has to be raised from, for example, 200 ° C. to 500 ° C., it takes about 3 hours to raise the temperature. Therefore, during the temperature drop or temperature rise, the dummy steel plate is sandwiched and transported. Therefore, not only the line startup and shutdown, but also high response to heat cycle changes. There was a problem that could not get.

  Therefore, the present invention provides a furnace temperature control method and a furnace temperature control device for a continuous annealing furnace that can improve the energy efficiency of the continuous annealing furnace and improve the responsiveness to changes in the furnace temperature. is there.

  The present invention relates to a furnace temperature control method for controlling the inside of a furnace zone of a continuous annealing furnace to a predetermined furnace temperature. (1) Sensible heat of exhaust gas generated by a heating burner in a heating zone of a continuous annealing furnace, and an overaging zone Heat exchange with the ambient gas in the furnace to control the furnace temperature in the overaging zone to a predetermined temperature, (2) sensible heat of exhaust gas generated by the heating burner in the heating zone of the continuous annealing furnace, and continuous annealing In the second half of the furnace, heat is exchanged with the atmospheric gas in the temperature adjustment zone for adjusting the temperature of the steel strip introduced to the hot dip galvanization pot connected to the inlet side of the hot dip galvanization pot via a snout. The furnace temperature is controlled to a predetermined temperature.

  In the above method, exhaust gas is introduced into the hot air generator, a heat exchanger is disposed in the exhaust gas system exhausted through the hot air generator, and the heat exchanger has an overaging zone or temperature control. The atmosphere gas in the zone is introduced to control the furnace temperature in the overaging zone or the temperature adjustment zone to a predetermined temperature.

  In addition, a heat exchanger that cools the temperature of the atmospheric gas is disposed in the circulation system of the atmospheric gas, and the heat exchanger of the circulation system and the heat exchanger of the exhaust gas system are switched depending on the temperature of the atmospheric gas. Good.

  The present invention also provides a chimney that disperses the exhaust gas discharged from the hot air generator by disposing a hot air generator that adjusts the temperature of the exhaust gas in the exhaust gas path that is generated by the heating burner in the heating zone of the continuous annealing furnace. A heat exchanger for introducing an atmospheric gas in an over-aged zone or a temperature adjusting zone into the exhaust gas passage between the two and exchanging heat with the sensible heat of the exhaust gas from the heating zone is provided. Moreover, in the said apparatus, you may arrange | position and switch in a circulation system path | route which circulates atmospheric gas. And the introduction method of atmospheric gas into the furnace is a method in which atmospheric gas is blown to the hearth roll so that the temperature change response of the hearth roll with a large heat capacity has a large influence on the steel plate temperature which is the final target. Introduce into the furnace.

  In the present invention, since the heat burner exhaust heat in the heating zone of the continuous annealing furnace can be reused by adjusting the temperature with a hot air generator and heat exchange, the energy efficiency of the entire continuous annealing furnace can be improved. .

  Further, in the present invention, the temperature of the atmospheric gas can be quickly raised or lowered, so that the response to the furnace temperature control can be made in a short time with respect to line startup, shutdown, or heat cycle change. improves.

  In the present invention, exhaust gas exhausted from a heating burner used in a heating zone or soaking zone is installed with a hot air generator equipped with a burner, and the combustion amount is controlled to control the exhaust gas temperature (exposure). The temperature of the furnace in the overaging zone or the temperature control zone is controlled by exchanging heat with the ambient gas in the overaging zone or the temperature regulation zone. The overaging zone or temperature control zone is generally intended to maintain the plate temperature, so the amount of heat required for steady operation is mainly the heat dissipated in the furnace, and the required amount of heat is small. The sensible heat of exhaust gas can be used.

  When the combustion amount of a heating zone or a soaking zone heating burner decreases, the combustion amount of the hot air generator is increased and the necessary amount of heat is supplied to the overaging zone or the temperature control zone. In addition, if the exhaust gas temperature is greatly reduced due to a decrease in the amount of combustion in the heating zone or the soaking zone, a heat exchanger for exchanging heat with the atmospheric gas is used to reduce the amount of combustion in the hot air generator. Part of the exhaust gas after passing through can be returned to the entry side of the hot air generator. When the amount of exhaust gas is small to obtain a predetermined amount of exchange heat, and the exhaust gas temperature exceeds the heat resistance temperature of the heat exchanger, open the air valve and introduce air to increase the amount of exhaust gas. While maintaining, the exhaust gas temperature after the hot air generator is lowered. Further, even when the temperature of the atmospheric gas becomes too higher than the desired temperature, the air valve is used to adjust the temperature.

  In the furnace temperature control, the combustion amount of the hot air generator is controlled so that the target furnace temperature is reached in the furnace temperature mode. Again, when the hot air temperature downstream of the hot air generator becomes the heat-resistant temperature of the heat exchanger, air is introduced and lowered. In the plate temperature control mode, as shown in FIG. 4, the set furnace temperature is calculated from the set plate temperature by the plate temperature control model, and this is controlled as a target.

  When the furnace temperature is increased in accordance with the heat cycle change, the furnace temperature can be quickly increased by increasing the amount of heat input by increasing the combustion amount of the hot air generator. Moreover, when lowering | hanging a furnace temperature with a heat cycle change, a furnace temperature can be rapidly lowered | hung by switching a heat exchanger to a gas-water heat exchanger.

  FIG. 1 is a schematic layout of an embodiment in which the present invention is applied to the continuous annealing furnace shown in FIG. 7, and the same components as those in FIG.

  The heating zone 3 is heated by a heating burner such as a radiant tube burner, and the exhaust gas of the heating burner is collected in the plenum chamber 2 that keeps the pressure uniform by the exhaust gas pipe 14, and the exhaust gas is led to the flue by the exhaust gas blower 20 whose rotational speed is controlled. It is burned. Further, the rotation speed of the exhaust gas blower 20 is controlled so that the heating burner outlet pressure becomes an appropriate pressure for each combustion load. In addition, this invention is applicable to all the heating burners which generate | occur | produce exhaust gas, such as a direct fire burner and a thermal storage type radiant tube burner.

  First, the exhaust gas from the heating burner in the heating zone 3 is drawn by the exhaust gas blower 20 and sent from the plenum chamber 2 to the heat exchanger 16, and a preheating gas for preheating the steel strip 13 in the heat exchanger 16 is used. Heat by heat exchange. The preheating gas is circulated through the preheating gas duct 17, the preheater 1, the preheating recovery exhaust gas duct 18, and the heat exchanger 16 by the preheating gas circulation blower 19.

  Conventionally, the exhaust gas of the heating burner in the heating zone has been exhausted from the chimney 25 as it is through the exhaust gas blower 20 after exchanging heat with the preheating gas in the heat exchanger 16, as shown in FIG. In the invention, the exhaust gas of the heating burner exhausted from the chimney 25 by the following flow can be effectively used.

  A hot air generator 21 is installed downstream of the exhaust gas blower 20, and the exhaust gas is heated by the hot air generating burner 22 provided in the hot air generator 21 by the hot air generator 21, and the generated hot air reaches a desired gas temperature. Adjusted. The heat exchanger 23 exchanges heat with an overaged atmosphere gas (inert gas or reducing gas), and then the exhaust gas is exhausted from the chimney 25.

  Heating of the exhaust gas in the hot air generator 21 is performed by inputting the measured temperature measured by the furnace thermometer 29 and the plate thermometer 28 installed in the overaging zone 7 to the control devices 30 and 31 and performing arithmetic processing on the control valve. 32 is adjusted to adjust the combustion amount of the hot-air generating burner 22 of the hot-air generating device 21, and the exhaust gas temperature is controlled to control the temperature of the atmosphere gas for heat exchange.

  The circulation blower 26 that circulates the atmosphere gas in the overaging zone 7 sends the atmosphere gas exchanged by the heat exchanger 23 to the overaging zone 7, and heats the atmosphere gas exhausted from the overaging zone 7 from the circulation duct 27. Circulate to exchanger 23. The circulation blower 26 is controlled at the rotational speed so that the rotational speed can be controlled at the time of steady state, rapid heating and rapid cooling such as heat cycle change, line startup and shutdown.

In this embodiment, when the heating burner in the heating zone 3 is at the maximum combustion load, the outlet gas temperature of the heat exchanger 16 is about 600 ° C. and 43000 Nm ³ / hr, and this is heated by the hot air generator 21 to 500,000 kcal. / Hr is heated to about 630 ° C., and the atmosphere gas is heated by the heat exchanger 23, so that a heat amount of about 1 million kcal / hr is input to the overaging zone 7 to cover the amount of heat dissipated in the furnace zone. The furnace temperature can be maintained at a furnace temperature in a desired overaging zone.

For example, when the load of the heating burner in the heating zone 3 is reduced to 30% combustion load, the outlet gas temperature of the heat exchanger 16 for the preheating furnace is about 450 ° C. and 22000 Nm ³ / hr. Heat to 1,500,000 kcal / hr with a generator to a temperature of about 680 ° C. The furnace temperature can be maintained by heat-exchanging the atmospheric gas with the heat exchanger 23 for an overaging zone.

  When the burner load in the heating zone 3 reaches the minimum combustion state, the combustion amount of the hot air generator 21 is increased, but the exhaust gas amount of the heating burner in the heating zone 3 is reduced, and the heat exchanger 23, the temperature at the outlet side of the hot air exceeds the heat-resistant temperature. Therefore, the amount of exhaust gas is increased by introducing air, and the hot air generator 21 is heated by 3.5 million kcal / hr. Alternatively, if the heat exchanger 16 for the preheating furnace is bypassed via the duct 45 and the exhaust gas is supplied at a high temperature, the amount of heating heat in the hot air generator can be reduced to 2.8 million kcal / hr.

  In order to simplify the work, in all operating cases, the case where the preheater heat exchanger 16 is bypassed or the case where the preheater heat exchanger 16 is not installed, The required heat input is about 0.25 compared to the conventional case. In the case where the preheater heat exchanger 16 is not bypassed, the specifications of the preheater heat exchanger 16 and the overage zone heat exchanger 23 are determined in consideration of the balance between the pretropical zone, the heating zone, and the overaging zone. Therefore, a continuous annealing furnace with high thermal efficiency can be realized.

  FIG. 4 shows a flowchart of the furnace temperature control of the present invention.

  First, the furnace temperature regulator has a heat balance model of the furnace temperature in the overaging zone and the temperature adjustment zone, a heat balance model in the heat exchanger, and a heat balance model of the heating zone. Basic furnace temperature control is feedback control that controls the combustion amount of the hot air generator based on the deviation between the set furnace temperature and the actual furnace temperature. The exhaust gas flow rate and exhaust gas temperature at each stage may be measured values, or may be calculated sequentially using the heat transfer model based on the actual amount of combustion in the heating zone.

  First, based on the set furnace temperature, the rotational speed of the hot air circulation blower is set by the heat transfer model. Since the flow rate and temperature of the exhaust gas coming from the heating zone change depending on the plate passing condition of the steel plate, the hot air circulation blower rotates according to the heat balance model of the furnace temperature and the heat balance model in the heat exchanger whenever the plate passing condition changes. Set the number. At the same time, the gas temperature on the inlet side and outlet side of the heat exchanger of the atmosphere gas in the furnace zone is also measured or calculated. The amount of air is calculated from the rotational speed of the hot air circulation blower, and the amount of exchange heat is calculated from the gas temperatures on the inlet and outlet sides. However, since the furnace temperature is basically controlled by controlling the amount of combustion of the hot air generator, it is practical to set the rotation speed of the circulation blower only when the plate passing condition is changed.

  When the amount of exchange heat is insufficient due to maintaining the set furnace temperature or increasing the furnace temperature, the combustion amount of the hot air generator is increased, but heat exchange is performed based on the actual exhaust gas temperature after the hot air generator and the heat balance calculation of the heat exchanger. If the heat-resistant temperature limit of the vessel and the exhaust gas flow rate are insufficient, open the air valve and increase the volume of exhaust gas.

  When the exhaust gas temperature on the outlet side of the heat exchanger is lower than the exhaust gas temperature on the outlet side of the hot air generator, the hot air return valve 47 is set so as to recirculate a flow rate equivalent to the amount of exhaust gas caused by combustion in the hot air generator. Control.

  Conversely, when it is desired to lower the furnace temperature, the fuel amount of the hot air generator is lowered. If the temperature still does not drop sufficiently, the atmosphere gas is switched to the cooling heat exchanger 42 and cooled.

  For feed-forward control, the amount of heat required to maintain the furnace temperature at each temperature is calculated by the furnace temperature regulator using the heat transfer models described above, and the exhaust gas flow rate, exhaust gas temperature, and heat exchanger heat balance calculation. From the above, the required amount of combustion of the hot air generator is calculated and controlled predictively. At that time, the exhaust gas temperature after the hot air generator and after the heat exchanger is also calculated, and the air valve and the hot air return valve are also predicted and controlled as described above.

  In the plate temperature control mode, as described above, the set furnace temperature is calculated from the set plate temperature and controlled by the plate temperature control model as shown in FIG.

  In the present example, as a result of testing for responsiveness, for example, the time for raising the furnace temperature from 200 ° C. to 500 ° C. is about 30 minutes as shown in FIG. Compared to this, the response time can be greatly shortened.

  FIG. 2 shows a schematic layout of an embodiment in which the present invention is applied to the cooling adjustment zone of the hot dip galvanizing equipment shown in FIG. 8, and the same components as those shown in FIGS. 1 and 8 are denoted by the same reference numerals. . 2, the exhaust gas from the heating burner in the heating zone 3 is introduced into the hot air generator 21 in the same manner as in Example 1, and the hot air generated by the heat exchanger 23 and the atmospheric gases in the cooling adjustment zones 34 and 35 are changed. The atmosphere gas is set to a set temperature by exchanging heat and circulating with the circulation blower 26.

  The heating of the burner exhaust gas in the hot air generator 21 is performed by inputting the measured temperature measured by the furnace thermometer 29 and the plate thermometer 28 installed in the cooling adjustment zone to the control device 38 and performing arithmetic processing on the control valve 32. Is adjusted to adjust the combustion amount of the hot air generating burner 22 of the hot air generating device 21 to control the temperature of the atmosphere gas to be heat exchanged.

  FIG. 3 shows a schematic layout of another embodiment of the present invention. The same components as those shown in FIGS. 1 and 2 are denoted by the same reference numerals.

  In this embodiment, a bypass duct 40 is provided in a circulation system for circulating atmospheric gas in the overaging zone 7 or the temperature adjusting zones 34 and 36 and a heat exchanger 42 is added. The circulation duct 27 of the heat exchanger 23 and the bypass duct 40 of the heat exchanger 42 are provided with switching valves 41 and 43, respectively. By switching the switching valves 41 and 43, the heat exchanger 23 is used for heating. 42 is used for cooling.

  For example, when lowering the furnace temperature from 500 ° C. to 200 ° C., the hot air generator 21 is stopped, the supply of exhaust gas to the heat exchanger 23 is stopped, and the atmospheric gas is heated by switching the switching valves 41 and 43. The temperature of the atmospheric gas is lowered using the exchanger 42.

  As a result of testing for responsiveness, the time for lowering the furnace temperature is about 10 minutes, as shown in the trend of FIG. 5, and can be significantly shortened compared to the time required for about 2 hours in the past. The responsiveness has been greatly improved.

  FIG. 10 shows an equipment configuration of an embodiment in which the present invention is applied to a continuous annealing furnace using a regenerative burner in a heating zone.

  In the present embodiment, the heating zone 3 employs a heat storage type radio and tube burner, and the exhaust gas temperature is lower than that of the radio and tube burner of the first embodiment, and is about 200 to 300 ° C. depending on the combustion load. The exhaust gas is collected in the plenum chamber 2 through the exhaust gas pipe 14 and guided to the flue by the exhaust gas blower 20. Since the exhaust gas temperature is low, unlike the first embodiment, there is no preheat heat exchanger for preheating the steel strip, but the exhaust gas that has passed through the heat exchanger 23 that exchanges heat with the overaged atmosphere gas is used as the exhaust gas blower. A hot air return duct 46 that returns to the front 20 is installed.

  When there is no hot air return duct 46, the furnace temperature in the overaging zone cannot be maintained unless the hot air generator 21 supplies a heat quantity of 3.5 million kcal / hr when the burner in the heating zone is in the lowest combustion state. By installing the return duct 46 and further recirculating part of the hot air, the amount of heat in the hot air generator 21 could be reduced to 2.9 million kcal / hr. Here, the amount of gas recirculated through the hot air return duct 46 is controlled to be equal to the flow rate of the hot air generator flue gas from the relationship of pressure balance.

  If the exhaust gas after passing through the heat exchanger for heat exchange with the overaged atmosphere gas is higher than the exhaust gas temperature on the hot air generator entry side, a part of the exhaust gas after the heat exchange is Returning to the entry side of the generator, mixing with the exhaust gas on the entry side of the hot air generator, and recirculating will improve the thermal efficiency. As described above, when the heat storage radiator and tube burner is employed in the heating zone, the exhaust gas temperature supplied to the hot air generator is lowered, and this hot air recirculation system is particularly effective.

  As a method for introducing the atmospheric gas in the furnace, the temperature of which has been adjusted by the heat exchanger, into the furnace, a method of spraying on the hearth roll as shown in FIG. 11 is adopted. This is for making the surface temperature of the hearth roll contacting the steel plate follow the furnace temperature setting change earlier than the furnace temperature. For example, when the plate temperature setting of the overaging zone is lowered by 100 ° C., it is estimated that both the atmospheric gas temperature and the hearth roll temperature are about 100 ° C. higher than the target at the beginning of the reduction. In this case, if the steel sheet is put at a plate temperature lower by 100 ° C. on the side where the overaging zone is entered, the amount of heat received by the steel plate from the relatively high hearth roll is about eight times the amount of heat received by the steel plate from the atmospheric gas. What? Therefore, in order to increase the responsiveness of the plate temperature control, a method of blowing the atmospheric gas into the furnace was adopted to increase the responsiveness of the hearth roll temperature change.

  In addition, the response time of the hearth roll temperature change was reduced to 2/3 or less as compared with the natural convection heat transfer of normal atmospheric gas and hearth roll.

  The present invention described above requires a heating zone that is a high-temperature part of a continuous annealing furnace, selection of a soaking zone equipment configuration and a heating device, and an overaging zone and a temperature regulation zone in which the furnace temperature is controlled using exhaust gas. The optimum application method varies depending on the temperature pattern. However, by applying the present invention, an equipment configuration that greatly improves the delay in responsiveness to changes in the set furnace temperature depending on the steel type, which is a problem due to the recent trend toward multi-product production, and also improves energy efficiency. it can.

It is a schematic layout of the Example which applied this invention to the continuous annealing furnace shown in FIG. It is a schematic layout of the Example which applied this invention to the cooling adjustment zone of the hot dip galvanization equipment shown in FIG. It is a schematic layout of another Example of this invention. It is a flowchart of the furnace temperature control of this invention. It is a graph which shows the pattern at the time of this invention and prior art furnace temperature fall. It is a graph which shows the pattern at the time of furnace temperature temperature rising of this invention and a prior art. It is a schematic layout of a continuous annealing furnace. A schematic layout of a continuous annealing furnace of a hot dip galvanizing facility is shown. It is a schematic layout of conventional exhaust gas utilization. It is a schematic layout of the Example which applied this invention to the continuous annealing furnace which used the thermal storage type burner for the heating zone. It is the schematic which shows the introduction method of the atmospheric gas in the furnace.

Explanation of symbols

1 Preheater 2 Plenum chamber 3 Heating zone 4 Soaking zone 5 Slow cooling zone 6 Quench zone (Primary cooling zone)
7 Overaging zone 82nd cooling zone 93th cooling zone 10 Quench device 11 Deflector roll 12 In-furnace roll 13 Steel strip 14 Exhaust pipe 15 Exhaust gas duct 16 Heat exchanger 17 Preheating exhaust gas duct 18 Preheating recovery exhaust gas duct 19 Preheating circulation Blower 20 Exhaust gas blower 21 Hot air generator 22 Hot air generator burner 23 Heat exchanger 24 Exhaust gas duct 25 Chimney 26 Hot air circulation blower 27 Hot air circulation duct 28 Plate thermometer 29 Furnace thermometer 30 Controller 31 Controller 32 Adjusting valve 33 Quench zone 34 Cooling adjustment zone 35 Cooling adjustment zone 36 Snout 37 Plating pot 38 Control device 39 Exhaust gas duct 40 Bypass duct 41 Switching valve 42 Heat exchanger 43 Switching valve
44 air valve 45 bypass duct 46 hot air return duct 47 hot air return valve 48 exhaust gas valve 49 atmosphere gas introduction header

Claims (8)

  In a furnace temperature control method for controlling the inside of the continuous annealing furnace to a predetermined furnace temperature, the sensible heat of the exhaust gas generated by the heating burner in the heating zone of the continuous annealing furnace and the atmospheric gas in the overaging zone are heated. The furnace temperature of the continuous annealing furnace is characterized by controlling the furnace temperature in the overaging zone to a predetermined temperature by introducing it into the overaging zone furnace by blowing the atmosphere gas to the hearth roll. Control method.   An exhaust gas is introduced into the hot air generator, a heat exchanger is disposed in the exhaust gas system exhausted through the hot air generator, and an atmospheric gas in the overaging zone is introduced into the heat exchanger. The furnace temperature control method for a continuous annealing furnace according to claim 1, wherein the furnace temperature in the overaging zone is controlled to a predetermined temperature.   In the furnace temperature control method for controlling the inside of the continuous annealing furnace to a predetermined furnace temperature, the sensible heat of the exhaust gas generated by the heating burner in the heating zone of the continuous annealing furnace and the galvanizing pot in the second half of the continuous annealing furnace The temperature adjustment is performed by heat exchange with the atmosphere gas in the temperature adjustment zone that adjusts the temperature of the steel strip introduced to the hot dip galvanizing pot connected to the inlet side of the steel via a snout, and blowing the atmosphere gas to the hearth roll A furnace temperature control method for a continuous annealing furnace, wherein the furnace temperature in the temperature adjustment zone is controlled to a predetermined temperature by being introduced into the zone furnace.   An exhaust gas is introduced into the hot air generator, a heat exchanger is disposed in the exhaust gas system exhausted through the hot air generator, and the atmospheric gas in the temperature adjustment zone is introduced into the heat exchanger. The furnace temperature control method for a continuous annealing furnace according to claim 3, wherein the furnace temperature in the temperature adjustment zone is controlled.   A heat exchanger for adjusting the temperature of the atmospheric gas is disposed in the circulation system of the atmospheric gas, and the heat exchanger of the circulation system and the heat exchanger of the exhaust gas system are switched according to the temperature of the atmospheric gas. The furnace temperature adjustment method for a continuous annealing furnace according to claim 2 or 4.   An exhaust gas path between the hot air generator that adjusts the temperature of the exhaust gas in the exhaust gas path generated by the heating burner in the heating zone of the continuous annealing furnace and the chimney that diffuses the exhaust gas discharged from the hot air generator A furnace temperature control device for a continuous annealing furnace, characterized in that a heat exchanger for introducing heat into the sensible heat of the exhaust gas from the heating zone by introducing atmospheric gas in the overaging zone or the temperature adjustment zone is disposed therein .   The furnace temperature control device for a continuous annealing furnace according to claim 6, wherein a heat exchanger is disposed in a circulation system for circulating the atmospheric gas.   In order to improve the thermal efficiency when the exhaust gas after passing through the heat exchanger for heat exchange with the atmosphere gas in the overaging zone or the temperature adjustment zone is higher than the exhaust gas temperature on the inlet side of the hot air generator, The furnace temperature control according to any one of claims 1 to 7, wherein a part of the exhaust gas after the heat exchange is returned to the inlet side of the hot air generator, mixed with the exhaust gas on the inlet side of the hot air generator, and recirculated. apparatus.

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