JPH09229354A - Heating furnace, method and apparatus for controlling combustion of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heating furnace, a method and apparatus for controlling the combustion of it which are capable of improving a thermal efficiency. SOLUTION: A heating furnace 1 comprises unit furnaces 1A and 1B provided with regenerative burners 2A to 2D on the side walls thereof. The regenerative burners 2A to 2D respectively comprise regenerators 2a to 2d and nozzles 3a to 3d. The respective unit furnaces 1A and 1B are provided with uptakes 4a and 4b. Thus, the furnace temperature of the heating furnace is uniformly controlled under a zone combustion control for changing the combustion state of the unit furnaces so that a fuel is saved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating furnace, a combustion control method therefor, and a combustion control device, and more particularly, to a batch combustion furnace used in a melting furnace for glass or aluminum, a heat treatment furnace for steel materials, and the like. The present invention relates to a heating furnace by zone combustion capable of saving energy, a combustion control method therefor, and a combustion control device.

[0002]

2. Description of the Related Art Conventionally, in a batch combustion apparatus used in a melting furnace for glass or aluminum or a heating furnace for steel materials, combustion control is performed so that the temperature in the furnace becomes uniform.
In such a batch-burning furnace, the sensible heat of the exhaust gas is directly discharged to the outside of the furnace without heat recovery, or the heat is recovered by a heat exchanger (recuperator) to preheat combustion air to about 600 ° C at most. Was being supplied to the heating furnace.

In recent years, in a heating furnace, a heat storage body formed of ceramic balls, a ceramic honeycomb structure, or the like is provided in a combustion air supply passage in the furnace and an exhaust gas exhaust passage in the furnace, and the heat storage body is provided through the heat storage body. A heat storage type alternating combustion burner that alternately performs combustion and exhaust gas emission is provided. In a heating furnace equipped with this heat storage type alternating combustion burner, the sensible heat of the combustion exhaust gas is stored in the heat storage body, and the combustion air is preheated by the recovered heat stored in the heat storage body to be supplied into the heating furnace. The heat recovery rate and the heat efficiency are improved. A heating device provided with this type of regenerative type alternating combustion burner is disclosed, for example, in Japanese Patent Laid-Open No. 6-257951 and Japanese Patent Laid-Open No. 7-4.
No. 638 and the like.

Referring to FIG. 4, a description will be given of a heating furnace equipped with a conventional heat storage type alternating combustion burner. The heating furnace 1 is provided with a pair of heat storage type burners 2A, 2C, 2B and 2D, respectively. The heat storage type burners 2A to 2D are heat storage bodies 2a.
2d and nozzles 3a to 3d, respectively. The fuel is supplied from the control valves 5a to 5d, ejected from the nozzles 3a to 3d into the furnace, and reacts with the combustion air that has passed through the heat storage body to burn it. The supply of combustion air and the discharge of exhaust gas are performed by controlling the switching control valves 6a and 6b. The control valves 5 a to 5 d and the switching control valves 6 a and 6 b are controlled by the control device 10. A temperature sensor 9 is provided inside the furnace.

In the figure, the regenerative burners 2B and 2C are in a combustion state, and the regenerative burners 2A and 2D are in a fire extinguishing state.
The combustion exhaust gas is discharged outside the furnace via the heat storage bodies 2a and 2d. When a predetermined time has elapsed, the regenerative burners 2B, 2
C extinguishes, and the regenerative burners 2A and 2D start burning. A pair of regenerative burners alternately repeats combustion and exhaust gas emission to perform alternating combustion to make the temperature in the heating furnace uniform. The calorific values during combustion of the regenerative burners 2A to 2D are equal. The thermal efficiency of the heating furnace is improved by providing the heating furnace with a regenerative alternating combustion burner.

[0006]

In a conventional heating furnace, a regenerative burner is used as a combustion device in order to improve thermal efficiency. The heat storage type burner is an excellent combustion device capable of achieving energy saving as compared with a conventional burner (one without a heat storage body). However, in recent years, as a heating furnace such as a batch combustion furnace, a heating furnace capable of further improving the heat transfer effect and further saving the fuel has been desired, and a combustion control method and device having excellent heat transfer efficiency is desired. It is rare. The present invention has been made in view of the above problems, and an object thereof is to provide a heating furnace capable of improving thermal efficiency, a combustion control method thereof, and a combustion control device thereof.

[0007]

Means for Solving the Problems The present invention has been made to achieve the above object, and the invention of claim 1 has the following features.
A heating furnace having a unit furnace capable of setting the furnace temperature for each unit furnace, including a unit furnace having a high calorific value during combustion and a unit furnace having a low calorific value during combustion or a calorific value due to combustion of zero. The heating furnace is characterized in that combustion control is performed while switching the combustion state of.

According to the first aspect of the present invention, the temperature of the heating furnace is changed while switching between the high temperature combustion zone (unit furnace having a high calorific value during combustion) and the low temperature combustion zone (unit furnace having a calorific value during combustion of zero). Since the heat transfer rate can be treated as a function of the fourth power of the combustion gas temperature, it means that the heat transfer rate is dramatically improved when the temperature becomes high. Is used to control the combustion of the heating furnace. To further explain, rather than uniformly heating the heating furnace at the combustion gas temperature Tg, (Tg +
By providing a high temperature combustion zone of (ΔTg) and a low temperature combustion zone of (Tg-ΔTg) for combustion, the heat transfer rate of (Tg + ΔTg) and (Tg-ΔTg) rather than Tg is the fourth power of the combustion gas temperature. Because it depends on the function, it will be dramatically increased. Therefore, the heat transfer efficiency to the object to be heated is improved by switching the high temperature combustion zone and the low temperature combustion zone to control combustion. That is, the total radiative heat transfer from the high temperature combustion zone and the low temperature combustion zone to the object to be heated is larger than the combustion gas radiative heat transfer at the average combustion gas temperature, so the fuel required to obtain the same heat transfer is In contrast to uniformly heating the combustion gas temperature Tg, controlling combustion by dividing the high temperature combustion zone and the low temperature combustion zone saves fuel and improves the thermal efficiency of the heating furnace.

The invention according to claim 2 is the heating furnace according to the invention according to claim 1, which comprises a unit furnace capable of setting the temperature inside the unit furnace, wherein combustion gas is supplied to each unit furnace. It is a heating furnace characterized by providing a smoke path for discharging, in addition to improving the thermal efficiency by the above heat transfer law, depending on the amount of exhaust gas discharged from the smoke path, from the unit furnace of the high temperature combustion zone to the low temperature combustion zone It is possible to improve the thermal efficiency by generating a flow of the combustion gas on the unit furnace side (in particular, the calorific value during combustion is zero) so that the sensible heat of the combustion gas can be effectively used.

[0010] The invention of claim 3 is based on claim 1 or 2.
In the heating furnace of the invention described in, a heating furnace characterized by providing a partition having an opening between each unit furnace of the heating furnace, while maintaining the independence of each unit furnace, It is possible to enable flow and improve thermal efficiency. The invention according to claim 4 is the heating furnace according to any one of claims 1, 2 and 3, wherein the unit furnace is provided with at least one set of regenerative burners, By providing at least one set of regenerative burners in each unit furnace, it is possible to form a regenerative alternating combustion burner and to improve the thermal efficiency.

According to a fifth aspect of the present invention, there is provided a combustion control method for a heating furnace comprising a unit furnace equipped with a combustion device, wherein the unit furnace having a high calorific value during combustion and the calorific value during a combustion is low or non- The heating is characterized in that the furnace temperature is controlled with a unit furnace in a combustion state as a pair, and the combustion state of the pair of unit furnaces is alternately switched at a certain time interval to set the furnace temperature to a predetermined temperature. This is a method for controlling combustion in a furnace. By alternately switching between a high temperature combustion zone and a low temperature combustion zone, the thermal efficiency can be improved by setting the temperature inside the heating furnace to a predetermined temperature.

According to a sixth aspect of the present invention, there is provided a combustion control method for a heating furnace comprising a unit furnace equipped with a combustion device, wherein the combustion device of the unit furnace is a heat storage burner and a unit having a high calorific value during combustion. The furnace temperature is controlled by setting a pair of a furnace and a unit furnace that has a low calorific value during combustion or is in a non-combustion state, and the combustion state of the pair of unit furnaces is alternately switched at a certain time interval. Is a predetermined temperature, the combustion state switching time is a combustion control method of the heating furnace, characterized in that it is set to an integral multiple of the alternating combustion time by the heat storage burner, the zone combustion switching time the alternating combustion time Is set to an integral multiple of 1 and the combustion control is performed by synchronizing the zone combustion switching with the combustion cycle of the heat storage type burner to control the heat capacity by combustion of the heat storage type burner for each zone. A combustion control method to achieve.

According to a seventh aspect of the present invention, there is provided a combustion control method for a heating furnace comprising a unit furnace equipped with a combustion device, wherein a unit furnace having a high calorific value during combustion and a unit furnace in a non-combustion state are burned as a pair. A heating furnace to be controlled, the combustion state of the unit furnace is alternately switched at a certain time interval to control the temperature inside the heating furnace, and the combustion gas of the unit furnace in the combustion state is set to the non-combustion state. A combustion control method for a heating furnace, characterized in that the temperature inside the heating furnace is controlled by discharging it from a smoke path of a unit furnace. This is a combustion control method that can improve the thermal efficiency because the flow between unit furnaces is possible and the heat from the flowing combustion gas can be used.

According to an eighth aspect of the present invention, in a combustion method in a heating furnace comprising a unit furnace equipped with a combustion device, a time interval for switching the combustion state in which the heating furnace is combustion controlled as a pair of unit furnaces is set. The combustion control method for a heating furnace according to any one of claims 5 to 7, characterized in that the temperature is set to 5 to 30 minutes. Even if homogenization cannot be achieved, and if it is too short, the heat transfer effect due to zone combustion cannot be achieved.Therefore, it is a value determined by the thermal inertia of the heating furnace, the furnace heat loss, the heat capacity of the heated object, etc. Assuming a combustion furnace, the lower limit is set to about 5 minutes because the thermal inertia of the heating furnace is about 2 to 3 minutes, and the upper limit is determined by the heat capacity of the object to be heated, furnace heat loss, etc., and is set to about 30 minutes. Set. From this point of view, the combustion control method is capable of improving the thermal efficiency of the heating furnace by setting the zone combustion switching time (cycle) in the range of 5 to 30 minutes.

According to a ninth aspect of the present invention, there is provided a combustion control device for a heating furnace comprising a unit furnace equipped with a combustion device, wherein the calorific value at the time of combustion with the first unit furnace which is in a combustion state is low or non-combustion. Combustion switching control means for alternately switching the combustion state of the second unit furnace in a certain state at certain time intervals, and exhaust gas for controlling combustion by discharging the combustion gas of the first unit furnace from the second unit furnace side to the outside of the furnace. A combustion control device for a heating furnace characterized by comprising an exhausting means, wherein the combustion control device allows the set exhaust gas amount to pass through a heat storage body in the case of a regenerative burner, and is optimally discharged from a smoke path. In order to achieve thermal efficiency, the switching time set by the combustion switching control means is set, and the exhaust gas exhaust amount exhausted from the regenerative burner and the exhaust gas exhaust amount from the smoke path are set by the exhaust gas exhausting means. It is intended to achieve optimum combustion control to control.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. One of the present inventions relates to a heating furnace, and the other invention relates to a combustion control method and a combustion control apparatus for the heating furnace. FIG. 1 is a perspective view showing an embodiment of a heating furnace according to the present invention, and this heating furnace is particularly suitable for a batch combustion furnace for melting glass, aluminum or the like. The heating furnace 1 is composed of unit furnaces 1A and 1B, and pipes 1a and 1c to which heat storage bodies 2a and 2c are connected are provided on a furnace side wall of the unit furnace 1A, and nozzles 3a for injecting fuel into the pipes 1a and 1c are provided. 3c is provided. Unit furnace 1B
On the side wall of the pipe 1b to which the heat storage bodies 2b and 2d are connected,
1d is provided, and nozzles 3b and 3d for injecting fuel into the pipes 1b and 1d are provided. Heat storage type burners 2A-2
D is formed by combining the heat storage bodies 2a to 2d and the nozzles 3a to 3d, respectively. In addition, unit furnaces 1A, 1B
Is provided with smoke passages 4a and 4b for discharging excess exhaust gas,
A partition partially having an opening, for example, a partition hanging from the upper part of the furnace is provided between the unit furnaces 1A and 1B so that the temperature inside the unit furnace can be controlled independently.

Although FIG. 1 shows a heating furnace provided with two unit furnaces each having a partition and a pair of regenerative burners, a heating furnace having two or more unit furnaces is also shown. Of course, even in that case, each unit furnace is provided with at least a pair of regenerative burners and a flue. Further, in the embodiment of FIG. 1, a smoke passage is provided for each unit furnace, but this smoke passage is not required, for example, except that the combustion gas is flowed across the unit furnaces for combustion control. However, although the present embodiment uses the heat storage type burner as the combustion device, it is a normal type burner (burner having no heat storage body).
When using, it is necessary to provide a smoke path for each unit furnace.

Next, referring to FIG. 2, a combustion control device and a combustion control method for the heating furnace will be described. This figure shows the piping system of combustion air, fuel gas and combustion exhaust gas, control valve,
The electrical system of the switching control valve and control fan is shown.
In the heat storage type burners 2A to 2D, the supply of combustion air and the discharge of combustion exhaust gas are controlled by switching control valves 6a and 6b, and the nozzles 3a to 3d are controlled by controlling the control valves 5a to 5d.
The fuel gas is supplied from d to the regenerative burners 2A to 2D and jetted into the furnace. The combustion state in the figure is
Combustion air is supplied from the switching control valves 6a and 6b into the furnace through the regenerative burners 2B and 2C, the control valves 5b and 5c are opened, and fuel gas is supplied into the furnace through the nozzles 3b and 3c. The control valves 5a and 5d are closed and the fuel gas is shut off. The combustion exhaust gas is adjusted so as to be discharged from the heat storage bodies 2a and 2d through the switching control valves 6a and 6b. Further, the unit furnaces 1A and 1B are provided with smoke passages 4a and 4b, and when exhausting the discharge amount of the combustion exhaust gas from the smoke passages 4a and 4b, the discharge amount is controlled by the control fans 7a and 7b. Each unit furnace is provided with temperature sensors 9a and 9b to measure the temperature inside the furnace.

The control device 8 receives temperature measurement values in each unit furnace, measurement values from a flow meter, etc. by the temperature sensors 9a and 9b, and controls valves 5a to 5d and switching control valves according to a program written in advance. 6a, 6b and control fan 7
a and 7b are controlled. In the figure, the regenerative burner 2
B and 2C are in a combustion state, and the regenerative burners 2A and 2D are in a fire extinguishing state (non-combustion state). Switching control valves 6a, 6b
By this, combustion air is supplied to the regenerative burners 2B and 2C, and exhaust gas is extracted from the regenerative burners 2A and 2D. The control valve 5b on the side of the heat storage burner 2B is opened, the control valve 5c on the side of the heat storage burner 2C is in a slightly throttled state, and the other control valves 5a and 5d are adjusted to be in the closed state.

By controlling in this manner, the calorific value due to the combustion of the regenerative burner 2B is increased to make the unit furnace 1B a high temperature combustion zone, and the calorific value due to the combustion of the regenerative burner 2C is set to a small value and the unit furnace 1A is set. Is the low temperature combustion zone. The pair of regenerative burners 2A and 2C repeat alternating combustion at predetermined time intervals (cycles), and the regenerative burner 2
Similarly, B and 2D also repeat alternating combustion at predetermined time intervals (cycles). The calorific values of the unit furnaces 1A and 1B at the time of combustion are different, the unit furnace 1A is a high temperature combustion zone and the unit furnace 1B is a low temperature combustion zone, and the combustion states of the unit furnaces 1A and 1B are alternately switched at a certain time interval, and The unit furnace set in the combustion zone is switched to the low temperature combustion zone, the unit furnace in the low temperature combustion zone is switched to the high temperature combustion zone, and the combustion state of each unit furnace is alternately switched back to control the temperature in the heating furnace uniformly. There is. The switching time between the low-temperature combustion zone and the high-temperature combustion zone (zone combustion switching time) is set to a value that is an integer multiple of the cycle of the alternating combustion burner, and is performed at a time that is an integer multiple of the cycle of the alternating combustion burner. The regenerative burner does not burn at the same time, and the combustion can be performed efficiently. This combustion control method is called a zone combustion control method.

Of course, there may be two or more unit furnaces. For example, in the case of a heating furnace in which three unit furnaces are connected in series,
In order to heat the object to be heated to a constant temperature, a high temperature combustion zone (first unit furnace), a low temperature combustion zone (second unit furnace),
Set to the high temperature combustion zone (3rd unit furnace) and switch to the low temperature combustion zone (1st unit furnace), high temperature combustion zone (2nd unit furnace), low temperature combustion zone (3rd unit furnace) in the next cycle However, it is obvious that the combustion state may be controlled to control the temperature in the furnace.

Of course, in the embodiment, the unit furnace is provided with a pair of regenerative burners, but a conventional burner (without a regenerator) is also used for zone combustion control for alternately switching between the high temperature combustion zone and the low temperature combustion zone. Is possible and is not limited to regenerative burners. When burning and heating each unit furnace by such a conventional burner, it is necessary to provide a smoke path in each unit furnace. Further, another combustion control method of the heating furnace will be described with reference to FIG.
The unit furnace 1A is set in a combustion state, and the other unit furnace 1B is set in a non-combustion state (the amount of heat generated by combustion is zero). Then, there is a combustion method in which the combustion gas in the unit furnace 1A is extracted from the smoke passage 4b on the unit furnace 1B side, and the zone combustion control which alternately switches the combustion state and the non-combustion state enhances the heat transfer efficiency. As a matter of course, it is well known that the thermal efficiency of the heating furnace can be further enhanced by providing the unit furnace with a heat storage type alternating combustion burner by a pair of heat storage type burners for zone combustion control.

Next, another embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. The figure shows another zone combustion control device, and shows the combustion state of a certain cycle. The regenerative burners 2B and 2D are in a combustion state, and the regenerative burner 2
A and 2C are in a non-combustion state. In the next cycle, the heat storage type burners 2B and 2D are set to the non-combustion state, and the heat storage type burners 2A and 2C are
To the combustion state. When the regenerative burners 2B and 2D are in a combustion state, the combustion air is supplied to the regenerative burners 2B and 2D via the switching control valve 6, and the exhaust gas from the regenerative burners 2A and 2C via the switching control valve 6. It has been pulled out. As described above, the fuel supply is combustion-controlled by synchronizing the operation of the switching control valve 6 and repeatedly opening and closing the control valves 3a to 3d. By controlling combustion in this way, the combustion gas and the exhaust gas are
The temperature of the object to be heated in the heating furnace 1 can be controlled by flowing between 1B.

Further, the combustion exhaust gas is extracted from the heat storage type burner in the non-combustion state so that the unit furnaces 1A, 1A
A flow of combustion exhaust gas is formed between B and the smoke passage 4
a and 4b are used to control the flow of combustion gas in the heating furnace 1. For example, in FIG. 3, the combustion gas can be poured from the unit furnace 1B to the unit furnace 1A in the non-combustion state by drawing the combustion gas from the smoke passage 4a to the outside of the furnace by the control fan 7a. Further, the amount of combustion gas discharged from the smoke passage varies depending on the amount of exhaust gas extracted from the heat storage body side, and can be controlled by the amount of exhaust of the control fans 7a and 7b. These flow rate controls are performed according to the control program of the controller 8. In this way, the thermal efficiency can be improved by flowing the combustion gas into the unit furnace in the non-combustion state. The control device 8 has control means for setting the switching time for zone combustion and adjusting the exhaust gas discharge amount for setting the combustion exhaust gas amount discharged from the smoke passages 4a, 4b.

In the embodiment shown in FIG. 3, the regenerative burners 2A, 2C and 2B, 2D for each unit furnace are alternately burned to produce a high temperature unit furnace (high temperature combustion zone) and a unit furnace in a non-combustion state (low temperature unit). It is obvious that the zone combustion control may be performed by alternately switching the combustion zones). At that time, the temperature of the object to be heated in the furnace is controlled to be constant by flowing the combustion gas from the high temperature combustion zone to the low temperature combustion zone. In this embodiment, the heating furnace 1 is the same as that in the above embodiment, but the peripheral control system can be simplified by a control method such as a control valve.

Next, thermal efficiency between the zone combustion control method of this embodiment and the conventional combustion control method will be described in comparison. The comparative example is shown in Table 1. This example is an experiment conducted on the melting furnace described in FIG. First, the surface temperature of the object to be heated in the heating furnace was set to about 1000 ° C. (constant), and the combustion gas temperature after preheating the combustion air was set to about 200 ° C. The experiment was conducted by setting the zone combustion switching time between the high temperature combustion zone and the low temperature combustion zone to 15 minutes.

The average furnace temperature Tg in the heating furnace is about 1200.
The temperature is set to 0 ° C, and the thermal efficiency at that time is set to 1 with reference to the case where the combustion air is not preheated (air temperature 25 ° C). In addition, the preheating temperature of the combustion air is set to 500 ° C and 10
The setting was performed at 00 ° C. Examples 1 and 2 in Table 1 are cases where the zone combustion control is performed, and Conventional Examples 1 and 2 are cases where the two zones are heated to a uniform temperature of 1200 ° C. and the zone combustion control is not performed. In the first embodiment, the preheating temperature of the combustion air is 500 ° C, and in the second embodiment, it is 1000 ° C. In Examples 1 and 2, the experiment was conducted in the combustion state (high temperature combustion zone, low temperature combustion zone) of the heating furnace in the embodiment shown in FIG.

[0028]

[Table 1]

In Example 1 of Table 1, the average furnace temperature (124
0/1150) means that the high temperature combustion zone is 1
It is set to 240 ° C., indicating that the low temperature combustion zone is set to 1150 ° C., and its average furnace temperature is set to 1200 ° C. (1195 ° C.) which is almost equal to that in Conventional Example 1. Example 2 and conventional examples 1 and 2 are as shown in Table 1. As is clear from this result, the thermal efficiency improves as the preheating temperature of the combustion air becomes higher. Compared with the case where each unit furnace of the heating furnace is heated to a uniform temperature, it is shown that the zone combustion control according to the present embodiment improves the thermal efficiency regardless of the air preheating temperature, and the heat transfer effect is improved. This means that the fuel consumed in the heating furnace can be saved.

As described above, the heating furnace of the present invention is suitable for batch combustion equipment, and is a heating furnace in which two or more unit furnaces are provided by providing a partition having an opening. The unit furnace can control the temperature independently. Further, the combustion state is switched at a certain time interval between a unit furnace having a high calorific value during combustion (high temperature combustion zone) and a low temperature unit furnace having a low calorific value during combustion or a unit furnace in a non-combustion state (low temperature combustion zone). It is heated by zone combustion control. The heat transfer in the furnace is mainly due to radiation, and the heat transfer rate is a function of the fourth power of the combustion gas temperature, which means that the heat transfer rate dramatically increases at high temperatures. Is a combustion control in which the heat transfer efficiency is increased by increasing the heat transfer rate to heat the object to be heated in the heating furnace. That is, in the heating furnace of the present invention, the total radiant heat transfer amount from the high temperature combustion zone and the low temperature combustion zone to the object to be heated in the heating furnace is larger than the radiant heat transfer amount from the combustion gas that uniformly burns both unit furnaces. It is what you do.

Further, at the time of zone combustion control, the control fan pulls the smoke out of the furnace to the outside of the heating furnace to flow the combustion gas from the high temperature combustion zone to the low temperature combustion zone, thereby further saving fuel. However, the combustion method in which the combustion gas is caused to flow using the smoke passage is suitable for the conventional type burner that does not use the regenerative burner. That is, the heating furnace is burned and controlled by allowing the heat recovery to flow through the unit furnace in the non-combustion state without depending on the heat storage body, and this zone combustion control method uniformly heats the conventional unit furnace. It saves more fuel than the combustion control method.

If the zone combustion switching time for each unit furnace by the zone combustion control is too long, the temperature uniformity of the object to be heated cannot be achieved, and if it is too short, the zone combustion control effect cannot be obtained. Therefore, the zone combustion switching time for each unit furnace in zone combustion control is preferably approximately 5 to 30 minutes, although it varies depending on the material to be burned. This zone combustion switching time is a value determined by the thermal inertia of the heating furnace, the heat loss of the furnace, the heat capacity of the object to be heated, etc., and the lower limit value is the heat inertia of the heating furnace is about 2 to 3 minutes. If the zone combustion is switched while the inertia is present, the heating of the object to be heated in the unit furnace cannot be performed sufficiently. Therefore, the thermal inertia in the furnace is eliminated and the heating effect by combustion is sufficient. The time is set to about 5 minutes. The upper limit value is determined by the heat capacity of the object to be heated, etc., and it is necessary to stop the combustion and start the combustion before the temperature of the object to be heated falls, and it is set to about 30 minutes. By setting the combustion switching time within this time range, the thermal efficiency of the heating furnace can be improved.

Further, in the heating furnace of the present invention, the burner installed in the heating furnace is not limited to the burner shown in the above embodiment, and may be a conventional burner or a regenerative burner. Further, a heat storage type burner is most preferable in order to form a uniform high temperature field from the viewpoint of energy saving. Further, by controlling the combustion by guiding the combustion gas from the high temperature combustion zone to the low temperature combustion zone, further energy saving can be achieved. Further, in the above embodiment, two unit furnaces are combined, but three or more unit furnaces may be provided by partitions provided in the furnace. For example,
Combustion control is performed by switching the high temperature combustion zone and the low temperature combustion zone in order in the unit furnace.

[0034]

As described above, according to the present invention,
By alternately switching between the high-temperature combustion zone and the low-temperature combustion zone for zone combustion control, the efficiency of heat transfer to the heated object in the heating furnace is improved, and the fuel consumption can be reduced compared to the conventional combustion control method. There is an advantage that the thermal efficiency of is improved and energy saving can be achieved. Of course, the thermal efficiency can be further improved by using the regenerative burner in the unit furnace forming the heating furnace. In addition, by providing a smoke channel in each unit furnace, it is possible to easily form a flow of combustion gas between unit furnaces, and the combustion gas is caused to flow from the high temperature combustion zone to the low temperature combustion zone to make the furnace of the heating furnace. The internal temperature can be controlled uniformly, the thermal efficiency of the heating furnace can be improved, and the fuel consumption can be further reduced.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a heating furnace according to the present invention.

FIG. 2 is a diagram showing a combustion control device of the above embodiment.

FIG. 3 is a diagram showing another combustion control device of the embodiment.

FIG. 4 is a diagram showing a conventional combustion control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heating furnace 1A, 1B Unit furnace 1a-1d Piping 2A-2D Heat storage type burner 2a-2d Heat storage body 3a-3d Nozzle 4a, 4b Smoke path 5a-5d Control valve 6a, 6b Switching control valve 7a, 7b Control fan 8 Control Device 9a, 9b Temperature sensor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location F27B 3/20 F27B 3/20 F27D 17/00 101 F27D 17/00 101A

Claims (9)

[Claims] 1. A heating furnace comprising a unit furnace capable of setting a temperature inside the furnace for each unit furnace, wherein the unit furnace has a high calorific value during combustion and the calorific value during combustion is low or the calorific value due to combustion is low. A heating furnace that controls combustion while switching the combustion state between zero unit furnaces. 2. A heating furnace including a unit furnace capable of setting the temperature inside the unit furnace, wherein a smoke passage for discharging combustion gas is provided for each unit furnace. The heating furnace described. 3. The heating furnace according to claim 1, wherein a partition having an opening is provided between the unit furnaces of the heating furnace. 4. The heating furnace according to claim 1, 2, or 3, wherein the unit furnace is provided with at least one set of regenerative burners. 5. A combustion control method for a heating furnace comprising a unit furnace equipped with a combustion device, comprising: burning a unit furnace having a high calorific value during combustion and a unit furnace having a low calorific value during combustion or a non-combustion state. A combustion control method for a heating furnace, characterized in that the furnace temperature is controlled by switching the state and the combustion state of at least two unit furnaces is switched at a certain time interval to set the furnace temperature to a predetermined temperature. 6. A combustion control method in a heating furnace comprising a unit furnace equipped with a combustion device, wherein the combustion device of the unit furnace is a regenerative burner, and the unit furnace having a high calorific value during combustion and the heat generation during combustion. The furnace temperature is controlled by switching the combustion state with a unit furnace with a low amount or non-combustion state, and the combustion state of the pair of unit furnaces is alternately switched at a certain time interval to set the furnace temperature to a predetermined temperature. And the switching time of the combustion state is set to an integral multiple of the alternating combustion time by the heat storage type burner. 7. A combustion control method for a heating furnace comprising a unit furnace equipped with a combustion device, wherein the unit furnace having a high calorific value during combustion and the unit furnace in a non-combustion state are paired for combustion control. , The combustion state of the unit furnace is alternately switched at a certain time interval to control the furnace temperature of the heating furnace, and the combustion gas of the unit furnace in the combustion state is output from the smoke path of the unit furnace in the non-combustion state. A combustion control method for a heating furnace, which comprises discharging and controlling the temperature inside the heating furnace. 8. A combustion control method in a heating furnace comprising a unit furnace equipped with a combustion device, wherein a time interval for switching the combustion state in which the heating furnace is combustion controlled as a pair of unit furnaces is 5 to 30 minutes. 8. The combustion control method for a heating furnace according to claim 5, wherein the combustion control method is set during the period. 9. A combustion control device in a heating furnace comprising a unit furnace equipped with a combustion device, wherein a first unit furnace which is in a combustion state and a second unit furnace which has a low calorific value during combustion or is in a non-combustion state. Combustion switching control means for alternately switching the combustion state of the second unit furnace at a certain time interval, and exhaust gas discharging means for controlling combustion by discharging the combustion gas of the first unit furnace from the second unit furnace side to the outside of the furnace. A combustion control device for a heating furnace.