JP5881785B2 - Combustion control method for continuous heat treatment furnace and remodeling method for continuous heat treatment furnace - Google Patents

Description

  In the present invention, a plurality of radiant tube burners are juxtaposed along the running direction of the strip running in the heat treatment furnace, fuel and combustion air are supplied to the radiant tube burner, and the fuel is burned in the radiant tube burner. Thus, the present invention relates to a combustion control method for a continuous heat treatment furnace and a method for remodeling the continuous heat treatment furnace in which a strip traveling in the heat treatment furnace is continuously subjected to heat treatment such as annealing. In particular, when fuel and combustion air are supplied to the radiant tube burner and the fuel is burned in the radiant tube burner, NOx is prevented from being generated during the combustion operation of the radiant tube burner, and the radiant tube burner It is characterized in that it is prevented from adhering.

  In continuous heat treatment of the traveling strip, conventionally, as shown in Patent Documents 1, 2, etc., a plurality of radiant tube burners are arranged in parallel along the traveling direction of the strip traveling in the heat treatment furnace, The radiant tube burner is supplied with fuel and combustion air, the fuel is burned in the radiant tube burner, and the strip running in the heat treatment furnace is continuously heat treated.

  Here, when supplying fuel and combustion air to the radiant tube burner and burning the fuel in the radiant tube burner, the amount of combustion air to be supplied is the theoretical air amount required to burn the fuel. In fact, if the fuel and combustion air are not mixed evenly, incomplete combustion occurs and soot is generated due to various causes, such as soot adhering to the radiant tube burner, causing problems in combustion. There is a problem that the heat is generated in the radiant tube burner and the radiant tube is deformed.

  Therefore, conventionally, when supplying fuel and combustion air to the radiant tube burner and burning the fuel in the radiant tube burner, the ratio of the combustion air amount actually supplied to the theoretical air amount, that is, It is proposed that the air ratio μ is set to about 1.15 to 1.30, and the amount of combustion air supplied to the radiant tube burner is considerably larger than the theoretical air amount to prevent generation of soot due to incomplete combustion. ing.

  However, when combustion is performed with the air ratio μ of the combustion air supplied into the radiant tube burner being about 1.15 to 1.30 in this way, the temperature of the flame at the time of combustion becomes high and NOx is reduced. There was a problem that the amount generated was increased and environmental sanitation was harmed.

  For this reason, in the conventional continuous heat treatment furnace, soot is prevented from adhering to the radiant tube burner to cause a failure in combustion, and the temperature of the flame at the time of combustion is increased to increase the amount of NOx generated. Could not be suppressed.

  Moreover, in the thing of patent document 1, the inside of a continuous heat treatment furnace is divided into a some zone along the course of a strip, and the combustion supplied to the radiant tube burner provided in each zone according to the required heat amount for every zone It has been proposed to control the gas flow rate.

  However, as shown in Patent Document 1, even when the flow rate of the combustion gas supplied to the radiant tube burner provided in each zone is controlled, the air ratio of the combustion air supplied to each radiant tube burner When μ is lowered, soot is deposited in the radiant tube burner, causing a problem in combustion. When the air ratio μ of combustion air is increased, the temperature of the flame at the time of combustion is increased, and the amount of NOx generated is reduced. It will continue to increase and still prevent soot from adhering to the radiant tube burner and causing problems in combustion, and suppress the increase in the amount of NOx generated due to the high flame temperature during combustion. I couldn't.

JP-A-8-35015 JP 2002-294347 A

  In the present invention, a plurality of radiant tube burners are juxtaposed along the running direction of the strip running in the heat treatment furnace, fuel and combustion air are supplied to the radiant tube burner, and the fuel is burned in the radiant tube burner. Thus, an object of the present invention is to solve the above-described problems in the case where the strip running in the heat treatment furnace is continuously heat-treated.

  That is, in the combustion control method for a continuous heat treatment furnace according to the present invention, the fuel and combustion air are supplied to the radiant tube burner as described above, and the combustion operation of the radiant tube burner is performed when the fuel is burned in the radiant tube burner. It is an object to suppress generation of NOx from time to time and to appropriately prevent the soot from adhering to the radiant tube burner.

  In the combustion control method for a continuous heat treatment furnace according to the present invention, in order to solve the above-described problems, a plurality of radiant tube burners are arranged in parallel along the traveling direction of the strip traveling in the heat treatment furnace, and the radiant Supplying fuel and combustion air to a tube burner, burning the fuel in the radiant tube burner, and continuously controlling the strip running in the heat treatment furnace, the combustion control method of the continuous heat treatment furnace, in each radiant tube burner A combustion control device that individually controls combustion and stop is provided, and the combustion control device is configured to stop combustion in some radiant tube burners and switch the radiant tube burner that stops combustion to perform the combustion operation. In a radiant tube burner to perform, N In the radiant tube burner in which the combustion operation is stopped while lowering the air ratio μ of the combustion air supplied so as to suppress the generation of x, the combustion air is supplied to the inside of the radiant tube burner. The wrinkles that occurred were removed.

  Here, in the radiant tube burner that performs the combustion operation as described above, when the combustion is performed with the air ratio μ of the combustion air to be supplied being lowered, an increase in the temperature of the flame during combustion is suppressed, and NOx On the other hand, since the air ratio μ of the combustion air is low, soot is easily generated in the radiant tube burner during combustion.

  On the other hand, when the combustion air is supplied to the radiant tube burner that has stopped the combustion operation, the soot generated in the radiant tube burner is decomposed by reacting with the combustion air as described above, and in the radiant tube burner. Soot is removed. Here, if the combustion air heated in advance by heat exchange with the combustion exhaust gas or the like is used as the combustion air supplied to the radiant tube burner that has stopped the combustion operation, the radiant tube burner that has stopped the combustion operation The temperature of the furnace is prevented from greatly decreasing, and the furnace temperature is prevented from decreasing.

  And, like the combustion control method of the continuous heat treatment furnace according to the present invention, by the combustion control device, while stopping the combustion in some radiant tube burners, and switching the radiant tube burner that stops the combustion, During combustion operation, the combustion operation is stopped even if soot is generated in the radiant tube burner because the air ratio μ of the combustion air is lowered so as to suppress the generation of NOx, and soot is deposited in the radiant tube burner. When the combustion air is supplied as described above, the soot in the radiant tube burner reacts with the combustion air and is decomposed, so that the soot is removed from the radiant tube burner.

  Here, as described above, the combustion control device stops combustion in some radiant tube burners and switches the radiant tube burner to stop combustion, so that NOx is generated in the radiant tube burner that performs the combustion operation. In the radiant tube burner that stops combustion operation while lowering the air ratio μ of the combustion air supplied so as to suppress the combustion, the combustion air is supplied and generated in the radiant tube burner. When removing soot, an open / close valve that switches between supply and stop of fuel is provided in the individual fuel supply pipe that supplies fuel individually to each radiant tube burner, and combustion air is supplied to each radiant tube burner individually. Provide radiant tube burner for individual air supply pipe Control means for controlling the supply quantity of combustion air which can be made to provide a.

  Further, in the combustion control method for a continuous heat treatment furnace according to the present invention, when stopping combustion in some radiant tube burners by the combustion control device as described above, the strip running in the heat treatment furnace is appropriately heat-treated. Therefore, it is preferable to control the number of radiant tube burners that stop combustion so that the temperature inside the heat treatment furnace is maintained at a predetermined heat treatment temperature.

  Further, in the radiant tube burner that performs the combustion operation as described above, when the air ratio μ of the combustion air to be supplied is lowered, the air ratio μ is 1.1 or less so that generation of NOx is appropriately suppressed. It is preferable to make it. For example, when the air ratio μ of the combustion air supplied to the radiant tube burner is 1.05, the amount of NOx generated is generally reduced by about 10 to 20% compared to the case where the air ratio μ is 1.20.

  In addition, when supplying combustion air to the radiant tube burner that has stopped the combustion operation as described above, if the amount of combustion air supplied increases, the inside of the radiant tube burner is cooled by the supplied combustion air. As a result, the temperature inside the heat treatment furnace may decrease. For this reason, it is preferable to make the quantity of the combustion air supplied to the radiant tube burner which has stopped combustion operation smaller than the quantity of the combustion air which supplies the radiant tube burner which performs combustion operation.

  Also, when combustion air is supplied to a radiant tube burner that has stopped combustion, the inside of the radiant tube burner is prevented from being cooled by the supplied combustion air, and the furnace temperature of the heat treatment furnace is prevented from decreasing. Therefore, it is preferable to use combustion air heated in advance by heat exchange with combustion exhaust gas or the like as the combustion air.

  Moreover, in the combustion control method of the continuous heat treatment furnace according to the present invention, a radiant tube burner that performs ON / OFF control of combustion is used, and only the combustion air is supplied to the radiant tube burner in which combustion is turned off. You can also.

  Further, in the remodeling method of the continuous heat treatment furnace according to the present invention, a plurality of radiant tube burners are juxtaposed along the running direction of the strip running in the treatment furnace, and fuel and combustion air are supplied to the radiant tube burner. A combustion control device that individually controls combustion and stop in each radiant tube burner in a continuous heat treatment furnace that supplies and burns fuel in the radiant tube burner and continuously heats the strip running in the heat treatment furnace. In addition to stopping combustion in some radiant tube burners and switching the radiant tube burner to stop combustion by the above-described combustion control device, NOx is generated in the radiant tube burner that performs the combustion operation To suppress the combustion to supply While performing combustion by lowering the air ratio μ of air in the radiant tube burner has stopped burning operation, so as to remove by supplying combustion air occurs in the radiant tube burner soot.

  In the combustion control method for a continuous heat treatment furnace according to the present invention, as described above, a combustion control device that individually controls combustion and stop in each radiant tube burner is provided, and by this combustion control device, a part of the radiant tube burner is provided. The combustion is stopped at the same time, and the radiant tube burner that stops the combustion is switched, and the air ratio μ of the combustion air supplied to the radiant tube burner that performs the combustion operation is lowered to suppress the generation of NOx during the combustion. At the same time, combustion air is supplied to the radiant tube burner that has stopped the combustion operation to remove soot in the radiant tube burner.

  As a result, in the combustion control method of the continuous heat treatment furnace according to the present invention, NOx is appropriately suppressed during the combustion operation of the radiant tube burner, and it is also appropriate that soot adheres to the radiant tube burner. Therefore, proper combustion can be stably performed in each radiant tube burner.

  Further, as shown in the modification method of the continuous heat treatment furnace according to the present invention, when the continuous heat treatment furnace is modified, the combustion control method for the continuous heat treatment furnace according to the present invention can be performed even in the conventional continuous heat treatment furnace. And the same effect can be obtained.

It is the schematic sectional drawing which showed the heat processing furnace used for the combustion control method of the continuous heat processing furnace which concerns on embodiment of this invention. In the combustion control method of the continuous heat treatment furnace according to the above-described embodiment, the combustion control device individually controls combustion and stop in each radiant tube burner, and shows a state in which combustion in some radiant tube burners is stopped It is a schematic explanatory drawing. In the combustion control method of the continuous heat treatment furnace according to the above embodiment, a partial schematic explanatory view showing a state where a radiant tube burner for stopping combustion is switched by a combustion control device. In the combustion control method of the continuous heat treatment furnace according to the above-described embodiment, the amount of combustion gas (fuel) and combustion air supplied to each radiant tube burner when individually controlling combustion and stoppage in each radiant tube burner It is a time chart which shows the state which switches. In the combustion control method of the continuous heat treatment furnace according to the above-described embodiment, it is a partial schematic explanatory view showing a modification example when individually controlling combustion and stop in each radiant tube burner by the combustion control device.

  Hereinafter, a combustion control method for a continuous heat treatment furnace according to an embodiment of the present invention will be specifically described with reference to the accompanying drawings. In addition, the combustion control method of the continuous heat treatment furnace according to the present invention is not limited to the one shown in the following embodiment, and can be implemented with appropriate modifications within a range not changing the gist of the invention.

  In this embodiment, as shown in FIG. 1, a plurality of rolls 11 are juxtaposed from the inlet 12 to the outlet 13 of the heat treatment furnace 10 at the lower part and the upper part in the heat treatment furnace 10. The strip 1 is introduced from the inlet 12 of the heat treatment furnace 10 in such a manner that the strip 1 is introduced from the inlet 12 to the outlet 13 in order to span the lower and upper rolls 11 in the heat treatment furnace 10. It is made to drive toward the exit 13.

  In the heat treatment furnace 10, a plurality of (for example, 100 or more) radiant tube burners 20 are juxtaposed along the traveling direction of the strip 1 traveling as described above, and the radiant tube burners 20 are provided with fuel. The fuel gas and the combustion air to be supplied are supplied to burn the fuel gas in the radiant tube burner 20 and are laid over the lower and upper rolls 11 as described above to pass through the heat treatment furnace 10 from the inlet 12 to the outlet 13. The strip 1 traveling toward the head is continuously heat-treated.

  Here, in supplying the fuel gas and the combustion air to each of the radiant tube burners 20, as shown in FIGS. 2 and 3, the fuel gas is supplied from the gas guide pipe 30 to the individual gas supply pipe (individual fuel supply pipe). ) 31 is guided to each radiant tube burner 20 through 31, and combustion air is guided from the air guide pipe 40 to each radiant tube burner 20 through the individual air supply pipe 41.

  The individual gas supply pipe 31 that guides the fuel gas to the radiant tube burner 20 is provided with an open / close valve 32 that switches between supply and stop of the fuel gas to the radiant tube burner 20.

  The individual air supply pipe 41 that guides the combustion air to the radiant tube burner 20 serves as a control means for controlling the supply amount of the combustion air supplied to the radiant tube burner 20. An on-off valve 42 for switching between supply and stop of air is provided, a bypass pipe 43 is provided so as to bypass the on-off valve 42, and a control valve 44 is provided on the bypass pipe 43.

  When the on-off valve 42 provided in the individual air supply pipe 41 is closed, the amount of combustion air guided to the radiant tube burner 20 through the bypass pipe 43 is controlled by the control valve 44. Further, when the on-off valve 42 is closed in this way, the on-off valve 42 is opened and the combustion air guided to the radiant tube burner 20 through the bypass pipe 43 is compared with the case where combustion air is supplied to the radiant tube burner 20. The amount of air is reduced. As the opening degree of the control valve 44 is increased, the effect of removing soot is increased, and soot attached to the radiant tube burner 20 can be removed in a short time.

  Further, in this embodiment, a combustion control device 50 for controlling the opening / closing of the on-off valve 32 provided on each individual gas supply pipe 31 and the on-off valve 42 provided on each individual air supply pipe 41 is provided. The combustion control device 50 controls combustion and stop in each radiant tube burner 20 individually.

  Here, in the radiant tube burner 20 that performs the combustion operation, the on-off valve 32 provided on the individual gas supply pipe 31 and the on-off valve provided on the individual air supply pipe 41 by the combustion control device 50. 42 is opened, fuel gas and combustion air are supplied to the radiant tube burner 20, and the fuel gas is burned in the radiant tube burner 20.

  Here, in burning the fuel gas in the radiant tube burner 20 in this way, in this embodiment, the air ratio μ of the combustion air guided to the radiant tube burner 20 through the individual air supply pipe 41 is lowered, for example, Combustion air is set to have an air ratio μ of 1.05 to 1.10.

  When combustion is performed with the air ratio μ of the combustion air set to 1.05 to 1.10 in this manner, the temperature of the flame during combustion is prevented from rising, and generation of NOx during combustion is suppressed. However, wrinkles easily occur in the radiant tube burner 20.

  In the radiant tube burner 20 that stops combustion, the on-off valve 32 provided on the individual gas supply pipe 31 and the on-off valve 42 provided on the individual air supply pipe 41 by the combustion control device 50. Is closed so that the fuel gas is not supplied to the radiant tube burner 20 through the individual gas supply pipe 31 and combustion is stopped, and the combustion air is not led to the radiant tube burner 20 through the on-off valve 42. . In this case, as for the combustion air, an appropriate amount of combustion air is supplied to the radiant tube burner 20 through the bypass pipe 43 provided with the control valve 44.

  When an appropriate amount of combustion air is supplied to the radiant tube burner 20 through the bypass pipe 43 to the radiant tube burner 20 whose combustion has been stopped in this way, the radiant tube burner 20 is generated as described above. Soot reacts with the combustion air and decomposes, and soot is removed from the radiant tube burner 20.

  Here, in this embodiment, when individually controlling the combustion and the stop in each radiant tube burner 20 by the combustion control device 50, as shown in FIGS. 2 and 3, some of the radiant tube burners 20 are used. , The on-off valve 32 provided on the individual gas supply pipe 31 and the on-off valve 42 provided on the individual air supply pipe 41 are closed so that the fuel gas is not supplied to the radiant tube burner 20 through the individual gas supply pipe 31. On the other hand, in the other radiant tube burner 20, the on-off valve 32 provided on the individual gas supply pipe 31 and the on-off valve 42 provided on the individual air supply pipe 41 are opened to burn the fuel gas and the combustion. The air is supplied to the radiant tube burner 20 so that the fuel gas is combusted.

  As shown in FIGS. 2 and 3, the radiant tube burner 20 for stopping the combustion is changed at an appropriate timing as described above, and the radiant tube burner 20 for burning the fuel gas, and the combustion is stopped for the combustion. The radiant tube burner 20 that supplies only air and removes soot is sequentially switched.

  Here, the number of the radiant tube burners 20 for stopping the combustion is not particularly limited, but the furnace temperature of the heat treatment furnace 10 is set to a predetermined temperature so that the strip 1 traveling in the heat treatment furnace 10 is appropriately heat treated. The number of radiant tube burners 20 that stop combustion is controlled so that the heat treatment temperature is maintained.

  For example, as shown in FIG. 4, while the number of radiant tube burners 20 for burning fuel gas is always the same, the combustion of the radiant tube burners 20 is stopped in order to adhere to the radiant tube burner 20. It is preferable to remove the soot.

  Further, when stopping the combustion of the plurality of radiant tube burners 20, in addition to stopping the radiant tube burners 20 for every predetermined number arranged in parallel in the running direction of the strip 1, a plurality of the radiant tube burners 20 arranged in parallel are also stopped. The radiant tube burners 20 may be stopped together for each combustion zone.

  Further, the ratio of the radiant tube burner 20 that stops the combustion varies depending on the traveling speed of the traveling strip 1, the mounting interval of the radiant tube burner 20, the soot removal time depending on the opening of the control valve 44, etc. It is appropriate to make 10 to 30% of the entire radiant tube burner 20. This is because if the ratio of the radiant tube burner 20 that stops combustion is small, the effect of removing soot is reduced, while if it is too high, the temperature inside the heat treatment furnace 10 may be lowered below a predetermined heat treatment temperature. Because.

  Further, when the radiant tube burner 20 that performs ON / OFF control of combustion is used for temperature adjustment, the temperature adjustment can be performed without switching the radiant tube burner 20 that stops combustion as described above. Therefore, it is possible to supply only the combustion air to the radiant tube burner 20 that turns off the combustion at the timing when the combustion is turned off to remove the soot in the radiant tube burner 20.

  Then, in the radiant tube burner 20 that burns the fuel gas by supplying the fuel gas and the combustion air, the air ratio μ of the combustion air guided to the radiant tube burner 20 is set to 1.05 to 1.10 as described above. Therefore, the temperature of the flame at the time of combustion is lowered, and the generation of NOx at the time of combustion is suppressed.

  Further, when the fuel gas is burned with the air ratio μ of the combustion air set to a low value of 1.05 to 1.10, soot is generated in the radiant tube burner 20, as described above. When the radiant tube burner 20 that burns the fuel gas and the radiant tube burner 20 that stops the combustion are switched at an appropriate timing, the supply of the fuel gas to the radiant tube burner 20 is stopped, and the radiant tube burner 20 burns. In the stopped state, as shown in FIG. 4, only an appropriate amount of combustion air is supplied through the bypass pipe 43 provided with the control valve 44 and is generated in the radiant tube burner 20 as described above. The soot is decomposed by reacting with the combustion air, and is in the radiant tube burner 20. Soot is to be removed.

  As a result, it is possible to appropriately prevent NOx from being generated in the radiant tube burner 20 that burns the fuel gas, and even if soot is generated in the radiant tube burner 20 during combustion, When the combustion is stopped, soot in the radiant tube burner 20 is removed by reacting with the combustion air as described above, and soot is prevented from adhering and accumulating in the radiant tube burner 20. Thus, stable combustion can be appropriately performed in each radiant tube burner 20 while suppressing the generation of NOx.

  In addition, when only the combustion air is supplied to the radiant tube burner 20 whose combustion is stopped as described above, in order to suppress the temperature in the radiant tube burner 20 from being lowered, Combustion air that has been heated in advance by heat exchange with combustion exhaust gas or the like can be used.

  In the above-described embodiment, when supplying an appropriate amount of combustion air to the radiant tube burner 20 whose combustion has been stopped, the on-off valve provided in the individual air supply pipe 41 that guides the combustion air to the radiant tube burner 20 The bypass pipe 43 is provided so as to bypass the valve 42, and the control valve 44 is provided in the bypass pipe 43. However, a method of supplying an appropriate amount of combustion air to the radiant tube burner 20 that has stopped combustion is as follows. It is not limited to such a thing.

  For example, as shown in FIG. 5, as a control means for controlling the amount of combustion air supplied to the radiant tube burner 20, a flow rate adjustment valve 45 is provided in the individual air supply pipe 41 that leads the combustion air to the radiant tube burner 20. It is possible to control the combustion air supplied to the radiant tube burner 20 by controlling the flow regulating valve 45 by the combustion control device 50.

  In this case, during the combustion operation of the radiant tube burner 20, the appropriate amount of combustion air as described above is supplied to the radiant tube burner 20 through the flow rate adjusting valve 45, so that NOx is reduced. Make sure that combustion is performed with minimal generation. On the other hand, when the combustion of the radiant tube burner 20 is stopped, the combustion air supplied to the radiant tube burner 20 through the flow rate adjusting valve 45 is reduced, so that the soot in the radiant tube burner 20 is used for the combustion supplied in this way. It decomposes by reacting with air so that the soot is removed from the radiant tube burner 20.

  Although not shown, the flow rate adjusting valve is used in place of the on-off valve 32 provided in the individual gas supply pipe 31, and the amount of fuel gas supplied to the radiant tube burner 20 is changed to change the radiant tube burner. It is also possible to adjust the amount of combustion at 20 individually.

  Also, in the existing continuous heat treatment furnace, as shown in the above-described embodiment, the supply and stop of the fuel gas to the radiant tube burner 20 are switched to the individual gas supply pipe 31 that guides the fuel gas to the radiant tube burner 20. In addition to providing the on-off valve 32, the individual control means for controlling the supply amount of the combustion air supplied to the radiant tube burner 20 is provided in the individual air supply pipe 41 that guides the combustion air to the radiant tube burner 20, Further, a combustion control device 50 for individually controlling the combustion and stop in each radiant tube burner 20 is provided. By this combustion control device 50, the combustion and stop in each radiant tube burner 20 are individually controlled as in the above embodiment. By controlling the control, the same effect as that of the above embodiment can be obtained. So as to.

1: Strip 10: Heat treatment furnace 11: Roll 12: Inlet 13: Outlet 20: Radiant tube burner 30: Gas guide pipe 31: Individual gas supply pipe (individual fuel supply pipe)
32: On-off valve 40: Air guide pipe 41: Individual air supply pipe 42: On-off valve 43: Bypass pipe 44: Control valve 45: Flow rate adjusting valve 50: Combustion control device

Claims (7)

  A plurality of radiant tube burners are juxtaposed along the running direction of the strip running in the heat treatment furnace, fuel and combustion air are supplied to the radiant tube burner, and the fuel is burned in the radiant tube burner to perform heat treatment. In a combustion control method of a continuous heat treatment furnace for continuously heat-treating a strip traveling in the furnace, a combustion control device for individually controlling combustion and stop in each radiant tube burner is provided. The radiant tube burner that stops combustion and switches the radiant tube burner that stops combustion, and in the radiant tube burner that performs the combustion operation, the air ratio μ of the combustion air supplied so as to suppress the generation of NOx μ While lowering the combustion In radiant tube burner has stopped operation, combustion control method for continuous heat treatment furnace and removing the occurred radiant tube burner to supply combustion air soot.   2. A combustion control method for a continuous heat treatment furnace according to claim 1, wherein an open / close valve for switching between fuel supply and stop is provided in an individual fuel supply pipe for supplying fuel individually to each radiant tube burner, and each radiant tube burner is provided in each radiant tube burner. A combustion control method for a continuous heat treatment furnace, wherein a control means for controlling a supply amount of combustion air supplied to a radiant tube burner is provided in an individual air supply pipe for individually supplying combustion air.   The combustion control method for a continuous heat treatment furnace according to claim 1 or 2, wherein when the combustion control device stops combustion in a part of the radiant tube burner, the furnace temperature of the heat treatment furnace is set to a predetermined heat treatment temperature. A combustion control method for a continuous heat treatment furnace, characterized in that the number of radiant tube burners that stop combustion is controlled so as to maintain.   The combustion control method for a continuous heat treatment furnace according to any one of claims 1 to 3, wherein an air ratio μ of combustion air supplied to a radiant tube burner that performs a combustion operation is set to 1.1 or less. A combustion control method for a continuous heat treatment furnace.   5. The combustion control method for a continuous heat treatment furnace according to claim 1, wherein the amount of combustion air supplied to the radiant tube burner that has stopped the combustion operation is the radiant tube that performs the combustion operation. A combustion control method for a continuous heat treatment furnace, characterized in that the amount is less than the amount of combustion air supplied to the burner.   The combustion control method for a continuous heat treatment furnace according to any one of claims 1 to 5, wherein the combustion air supplied to the radiant tube burner in which the combustion operation is stopped is preheated. Combustion control method for heat treatment furnace. A plurality of radiant tube burners are juxtaposed along the running direction of the strip running in the heat treatment furnace, fuel and combustion air are supplied to the radiant tube burner, and the fuel is burned in the radiant tube burner to perform heat treatment. In addition to the existing continuous heat treatment furnace that continuously heat-treats the strip running in the furnace, a combustion control device that individually controls combustion and stop in each radiant tube burner is provided. The radiant tube burner that stops combustion and switches the radiant tube burner that stops combustion in some radiant tube burners, and in the radiant tube burner that performs the combustion operation, the combustion air supplied to suppress the generation of NOx Combustion while lowering the air ratio μ In radiant tube burner has stopped operating, remodeling method of continuous heat treatment furnaces, characterized in that the removal of by supplying combustion air occurs in the radiant tube burner soot.

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