JPH1047664A - Furnace temperature control method for continuous heating furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To raise control responsiveness and give temperature distribution in longitudinal direction of a furnace with high accuracy by setting the substantial combustion time per unit time, wherein a pair of burners effect combustion operation alternately for each of the pairs, to perform the switching combustion control. SOLUTION: Regenerative burner devices 6A and 6B arranged downstream 31a of a first heater 3, and regenerative burner devices 6C and 6D arranged upstream 31b are put in combustion switching cycles different in pause time and combustion time. For example, the pause time in one cycle of the regenerative burner devices 6A and 6B is set shorter, and the substantial combustion time is set longer, and also the pause time in one cycle of the regenerative burner devices 6C and 6D is set longer, and the substantial combustion time of set shorter, whereupon the temperature within the furnace drops according as it goes to the position is the carry path on the upstream side 31b. Hereby, the temperature distribution in the longitudinal direction of the furnace can be set to downward inclination, facing in the progress direction of a slab.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a furnace temperature control method for a continuous heating furnace, and more particularly, to a continuous heating furnace capable of arbitrarily controlling a furnace temperature distribution in a furnace length direction. The present invention relates to a furnace temperature control method for a heating furnace.

[0002]

2. Description of the Related Art In a continuous heating furnace, the longitudinal direction of the furnace is divided into a plurality of zones (zones), a predetermined furnace temperature is set for each zone, and an object to be heated is continuously fed from the entrance side of each zone. This is a device that heats to a predetermined temperature while the object to be heated is transported in a furnace at a constant speed.

[0003] As a heating source of this continuous heating furnace, a heating source provided with a regenerative burner device in the furnace is known. The regenerative burner device comprises a pair of two burner units in which a regenerator and a burner are integrated, and supplies combustion air to the burner and exhausts combustion gas from the burner through the regenerator. The conventional continuous heating furnace is characterized in that the furnace temperature in the downstream zone is the furnace temperature in the upstream zone, or the furnace temperature in the upstream zone is higher. Since the furnace temperature in each zone affects the furnace temperature in the downstream zone, it has been difficult to control and maintain the furnace temperature in each zone at a desired temperature. In addition, the heating conditions of the objects to be heated, for example, the objects to be heated having different sizes or quantities (amount to be carried in) or the objects to be heated having different heating temperatures at the time of carrying in and the temperature at the time of extraction are sequentially combined and carried into the continuous heating furnace. When you do
There were many restrictions.

[0004] That is, when an object to be heated (a small quantity to be heated) is carried in after a large quantity to be heated (a large quantity to be heated), the amount of combustion is reduced due to the large quantity of the article to be heated. In the zone where the regenerative burner burns and increases, heat is stored in the furnace, and even if the regenerative burner in the zone stops burning due to a small amount of material to be heated, a small amount of Therefore, it takes time until the temperature in the furnace decreases to a predetermined temperature suitable for heating, and the low-temperature object to be heated cannot be heated at a predetermined temperature in a short period of time, which hinders improvement in work efficiency.

[0005] Even when an object to be heated at a high temperature (a high-temperature object) needs to be heated and then an object to be heated at a low temperature (a low-temperature object to be heated) is carried in, the low-temperature object can be heated. The heat was stored in the furnace in the zone where the regenerative burner device was burning by increasing the amount of combustion due to the heated material, and the combustion of the regenerative burner device in the zone was stopped for the low-temperature heated object. However, it takes time until the temperature in the furnace decreases to a predetermined temperature suitable for heating the low-temperature object, and the low-temperature object cannot be heated at the predetermined temperature in a short time. Hindered improvement.

Therefore, as a technique capable of solving the above-mentioned problem, for example, Japanese Patent Application Laid-Open No. H6-194054 (hereinafter referred to as Conventional Technique 1) and Japanese Patent Application Laid-Open No. H7-97619 (hereinafter referred to as Conventional Technique 2). ).

The prior art 1 discloses a regenerative alternating combustion burner system in which the inside of a furnace is divided into a plurality of zones, and in each of these zones, combustion air is supplied to a burner through a regenerator and combustion gas is discharged from the burner. Each of the heating furnaces is provided with at least one system, and the temperature in the furnace length direction of the heating furnace is detected by the temperature detecting means provided at least one in each zone, and a response is made based on the detection result of the temperature detecting means. This is a method for controlling the combustion of the regenerative alternating combustion burner system in the zone to be heated.If the furnace temperature is lower than the set temperature, the fuel supplied to the regenerative alternating combustion burner system is increased, and the furnace temperature is set to the set temperature. If higher, the fuel supplied to the regenerative alternating combustion burner system is reduced.

According to the prior art 1, the temperature in the furnace length direction of a heating furnace in which one or more regenerative alternating combustion burner systems are provided in a plurality of zones, respectively, is measured by temperature detecting means provided in each zone. By detecting the temperature and independently adjusting the furnace temperature of each zone based on the detection result, it is possible to arbitrarily set the furnace temperature pattern of the entire heating furnace.

Further, the prior art 2 relates to a heating furnace having a regenerative alternating combustion burner system for alternately supplying combustion air to a burner and exhausting combustion gas through a regenerator to provide one or more heating furnaces. Is a heating furnace provided with a combustion gas supply system for supplying a fuel gas that has passed through a regenerator of another unit furnace or zone to a unit furnace or zone via a combustion gas supply switching valve.

According to the prior art 2, when heating a low-temperature heating object after a high-temperature heating object, a low-temperature combustion gas is supplied into a unit furnace or a zone by a combustion gas supply system, and the unit furnace is heated in a short time. Alternatively, since the temperature in the zone is reduced to a temperature suitable for heating the low-temperature heated material, or the furnace temperature is adjusted to a temperature pattern suitable for heating the low-temperature heated material, the work efficiency is greatly improved.

[0011]

However, in the prior art 1, in order to make the temperature distribution in the furnace length direction of the heating furnace close to the set temperature with high accuracy, the fuel for the regenerative alternating combustion burner system installed in each zone is provided. Since the control for increasing or decreasing the supply amount is performed, a large number of fuel measurement devices and fuel flow rate adjustment valves are required, and furthermore, a complicated piping system is required, which may increase equipment costs.

Further, the prior art 2 is to provide a combustion gas supply system for supplying a fuel gas which has passed through a heat storage unit of another unit furnace or zone to a predetermined unit furnace or zone via a combustion gas supply switching valve. Since the heating furnace is brought close to the set temperature, the piping system is also complicated, which may increase the equipment cost.

Accordingly, the present invention has been made in view of the above-mentioned unsolved problems of the prior art, and provides an inexpensive system, enhances control responsiveness, and precisely controls the temperature distribution in the furnace length direction. It is an object of the present invention to provide a furnace temperature control method for a continuous heating furnace that can be attached.

[0014]

According to a first aspect of the present invention, there is provided a method for controlling a furnace temperature of a continuous heating furnace, wherein the furnace is heated to a predetermined furnace temperature. In a continuous heating furnace, which continuously heats the objects to be heated carried in from the entrance side and conveys them at a predetermined speed in the furnace length direction in the furnace and moves them to the exit side, a pair of burners, A plurality of sets of regenerative burners having a heat storage unit connected to a burner are installed at predetermined intervals in the furnace length direction in the furnace, and the heat storage type burners of the respective sets of regenerative burners are provided with the heat storage. A combustion control is performed by alternately switching a combustion burner that performs a combustion operation by supplying combustion air that has passed through the body and a non-combustion burner that performs a heat storage operation by passing exhaust gas in a furnace through the heat storage body at predetermined time intervals. At the same time, the pair of burners alternately By setting the actual combustion time per unit time for each pair of burners in each set, and performing the switching combustion control of each pair of burners based on the substantial combustion time, the inside of the furnace is This is a method of increasing the temperature with a temperature distribution in the furnace length direction.

Here, the actual combustion time per unit time means that when a pair of burners alternately switches between the combustion operation and the heat storage operation to perform the switching combustion, one of the burners performs the combustion operation in the unit time. And the time when the other vaner performs the combustion operation.

According to the furnace temperature control method for a continuous heating furnace according to the first aspect, when the furnace temperature is kept constant,
The pair of burners of all the regenerative burner devices perform switching combustion in a state where all the actual combustion times per unit time are set to the same time. As a result, the heating amounts of all the regenerative burners installed at predetermined intervals in the furnace length direction in the furnace become the same. The temperature distribution in the furnace length direction up to the outlet side in the furnace where the gas is carried out becomes uniform.

When the furnace temperature on the inlet side of the furnace is set high and the furnace temperature on the outlet side of the furnace is set low, the regenerative burner device installed on the inlet side of the furnace may be used. The pair of burners are set to have a substantial combustion time for a long time, and the pair of burners of a regenerative burner device installed on the outlet side in the furnace are set to have a substantial combustion time for a short time to perform switching combustion. As a result, the heating amount of the regenerative burner device on the inlet side in the furnace increases, and the heating amount of the regenerative burner device on the outlet side in the furnace decreases. Is in a state where the temperature distribution in the furnace length direction has a downward slope.

Further, when the furnace temperature on the inlet side of the furnace is set low and the furnace temperature on the outlet side of the furnace is set high, the regenerative burner device installed on the inlet side of the furnace may be used. The combustion is switched by setting the pair of burners to a short combustion time and setting the pair of burners of the regenerative burner device installed on the outlet side in the furnace to a long combustion time. As a result, the heating amount of the regenerative burner device on the inlet side in the furnace decreases, and the heating amount of the regenerative burner device on the outlet side in the furnace increases, so that from the inlet side in the furnace to the outlet side in the furnace. Is in a state where the temperature distribution in the furnace length direction has an upward slope.

As described above, by merely changing the actual combustion time per unit time of a plurality of sets of regenerative burners installed at predetermined intervals in the furnace length direction in the furnace, control responsiveness is improved and high accuracy is achieved. Can be given a temperature distribution in the furnace length direction.

According to a second aspect of the present invention, in the furnace temperature control method for a continuous heating furnace according to the first aspect, the pair of burners of each set alternately switches from a combustion operation to a heat storage operation and from a heat storage operation to a combustion operation. During one switching cycle, by providing an operation pause time to suspend all the combustion operation and the heat storage operation, and by making this operation pause time a long time or a short time,
This is a method for setting the substantial combustion time for each pair of burners.

According to the method for controlling the temperature of the continuous heating furnace according to the second aspect of the present invention, the actual combustion time for each pair of burners in each set can be set simply by providing a long or short operation downtime. Therefore, a special regulating valve and a piping system for supplying and stopping fuel are not required, and an inexpensive furnace temperature control system can be provided.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an embodiment when the present invention is applied to a continuous heating furnace.

In the figure, reference numeral 1 denotes a continuous heating furnace for heating a slab (object to be heated) which is continuously conveyed. The slab is carried in from the left side, and the pre-tropical zone 2, the first heating zone 3, the second Heating zone 4
The slab, which has been heated by sequentially passing through the solitary zone 5 and heated, is carried out from the right side and transported to the next step.

In the first heating zone 3, as shown in FIG.
Two regenerative burner devices 6A to 6D are provided. The waste gas discharged from these regenerative burner devices 6A to 6D is sucked by a waste gas suction fan 8 and discharged to the atmosphere from a chimney 9 shown in FIG.

As shown in FIG. 2, each of the regenerative burner devices 6A to 6D has a pair of burners 10A ₁ , 10A _{2 to} 10D ₁ and 10D ₂ disposed in the first heating zone 3. The burner 10 of the regenerative burner device 6A
A ₁ and 10A ₂ supply primary gas nozzles (not shown) to which combustion gas is supplied from the fuel gas supply ports 11a and 11b and combustion air, and waste gas generated in the first heating zone 3. A secondary air nozzle (not shown) for suction is provided inside, and the primary air nozzle and the secondary air nozzle communicate with the combustion air supply / discharge ports 18a and 18b. At the tip of the nozzle of the burners 10a and 10b,
Pilot burners 12a and 12b are provided. The fuel gas supply ports 11 for the burners 10A ₁ and 10A ₂
A and 11b are connected to a combustion gas supply source 16 for supplying M gas as a fuel gas via fuel cutoff valves 13a and 13b, and further via a main cutoff valve 14 and a fuel control valve 15.

The fuel control valve 15 is connected to the burner 10A.
_1, M gas at a predetermined flow rate relative to the 10A ₂ are possible flow adjustment so that it can supply. The pilot burners 12a, 12b are also connected to the fuel gas supply 16 via the shutoff valves 17a, 17b.

Furthermore, the burner 10A _1, 10A ₂ of the combustion air supply and discharge port 18a, 18b is branched pipes 19a, 19b
And the heat storage bodies 20a and 20b are disposed on the way of these branch pipes 19a and 19b. These branch pipes 1
9a and 19b are connected to an air blower 23 for pumping combustion air through an air cutoff valve 21a and 21b and further via a combustion air control valve 22.
Waste gas shut-off valves 24a, 24b connected in parallel with a, 21b
, And further connected to a waste gas suction fan 8 via a waste gas flow control valve 25.

Further, each of the heat storage bodies 20a and 20b serves as a heat storage medium along the gas flow passage, for example, having a diameter of 20 mm.
mm of alumina ball is filled, and the alumina ball exchanges heat with the high-temperature waste gas discharged from the first heating zone 3 to store heat. This heat storage is exchanged with low-temperature combustion air to be radiated. You.

Further, the fuel cutoff valves 13a and 13b, the main cutoff valve 14, the fuel control valve 15, the air cutoff valves 21a and 21b,
1b, combustion air control valve 22, waste gas cutoff valve 24a, 24
b and a waste gas flow control valve 25 are provided by a direct digital controller (hereinafter, referred to as DDC) 29 connected to a process computer 28 which controls the entire continuous heating furnace 1.
Is controlled by

Further, the other regenerative burner devices 6B to 6D
Burner 10B₁, 10B_Two-10D ₁, 10D_TwoBefore
Burner 10A of regenerative burner device 6A described above₁, 10A
_TwoThe same piping system and valves are provided.

The DDC 29 controls the fuel control valve 15, the combustion air control valve 22, and the waste gas flow control valve 25 so that the fuel flow rate, the combustion air flow rate, and the waste gas flow rate become predetermined values.
And a switching time for a pair of burners of each of the regenerative burners 6A to 6D is determined, and the fuel cutoff valves 13a, 13
b, air shutoff valves 21a, 21b and waste gas shutoff valve 24
a, 24b are controlled to open and close, one of the burners performing the combustion operation is switched to the heat storage operation, and the other burner performing the heat storage operation is switched to the combustion operation.

That is, the operation of the pair of burners 10A ₁ and 10A ₂ of the regenerative burner device 6A will be briefly described. One burner 10A ₁ performs a combustion operation and the other burner 10A ₂ performs a heat storage operation. Assuming that
For the burner 10A _1, the combustion air of the cool air condition being pumped by the air blower 23 from the outside air, combustion air regulating valve 22, via an air shut-off valve 21a is supplied to the regenerator 20a, the heat storage in the heat storage medium 20a It is preheated to a predetermined temperature by exchanging heat with the alumina balls. The preheated combustion air, the burner 10A ₁ combustion air supply and discharge port 18
a, and is mixed and burned with the fuel gas injected from the combustion nozzle to heat the furnace. At the same time, the other of the burner 10A _2, the secondary air nozzle combustion air supply and discharge port 18
b, the regenerator 20b, the waste gas shut-off valve 24b, and the waste gas flow control valve 25 communicate with the waste gas suction fan 8, and the waste gas in the furnace is sucked by the waste gas suction fan 8 to remove the heat storage body 20b. Is discharged through the heat storage body 20b.
The heat storage temperature of the heat storage body 20b is gradually increased so as to be suitable for preheating the combustion air by heat exchange between the alumina balls in the inside and the waste gas.

Here, FIG. 3 shows the inside of the first heating zone 3 in plan view, and the slab S passes at a predetermined speed on a transport path indicated by reference numeral 31 in the figure. The regenerative burner devices 6A to 6D inside the first heating zone 3 are provided on the side of the transport path 31 orthogonal to the traveling direction of the slab 3 on the downstream side 3 in the traveling direction.
1a is provided with a regenerative burner device 6A, and the upstream side 31b
Is provided with a regenerative burner device 6D, and between the regenerative burner devices 6A, 6D, other regenerative burner devices 6B, 6D.
C are arranged at predetermined intervals. Also, one of the burners 10A ₁ regenerative burner device 6A is disposed on one side of the transport path 31, the other of the burner 10A ₂ is traveling route 3
It is opposed to one of the burners 10A ₁ is disposed on one of the other side. And other regenerative burner devices 6B-6D also
One burner 10B _{1 to} 10D ₁ is provided on one side of the transport path 31.
Disposed to oppose each other by arranging the other burner 10B ₂ ~10D ₂ on the other side.

In the present embodiment, the DDC 29 performs the control described below so that the furnace temperature in the first heating zone 3 (required furnace temperature) required for heating the slab S is set. Here, the DDC 29 includes information such as the size and capacity of the slab S carried into the first heating zone 3, the target temperature required for heating the slab S, and the furnace time of the slab S passing through the transfer path 31. The slab information is stored in the process computer 28
Has been entered from time to time. Further, a furnace temperature sensor 30a is provided in the first heating zone 3, and the furnace temperature sensor 30a
The temperature of the furnace in the first heating zone 3 is also input to the DDC 29 from time a.

The DDC 29 controls the combustion switching of the regenerative burner devices 6A to 6D as shown in FIGS. 4 to 6 based on the current furnace temperature and slab information in the first heating zone 3 described above. Thereby, the temperature distribution in the furnace length direction of the first heating zone 3 can be set in various patterns. That is, FIG. 4 shows that the furnace length direction of the first heating zone 3 is in a constant high temperature state. while indicating combustion changeover time over chart of regenerative burner device 6A-6D for setting the required furnace temperature, at time T _1, one of the burners 10A for all regenerative burner device 6A~6D ₁ ~10D ₁ state of the fuel shut-off valve 13a and the air shut-off valve 21a opens, the waste gas shut-off valve 24a is closed, the other of the burner 10A ₂ to 10
D ₂ of the fuel shut-off valve 13b and the air shutoff valve 21b to a closed state, the waste gas shutoff valve 24b is opened condition, one of the burners 10A ₁ ~10D ₁ combustion state, the other burner 10A ₂
〜１０10D ₂ are in the heat storage state.

[0036] Then, at time T _2, one of the burners 10A ₁ ~10D ₁ of the fuel shut-off valve 13a and the air shut-off valve 21a is closed, the other of the burner 10A ₂ ~10D ₂
, The combustion state and the heat storage state of all the burners are stopped.

[0037] Then, at time T ₃ to rest time RT ₁ a short time has passed, all the regenerative burner device 6A~6
One burner 10A of D ₁ ~10D ₁ of the waste gas cutoff valve 2
The 4a opened and the other burners 10A ₂ ~10D ₂ fuel cutoff valve 13b, and the air shutoff valve 21b is opened condition, one of the burners 10A ₁ ~10D ₁ heat storage state, the other burner 10A ₂ ~10D ₂ Set to combustion state.

Next, a predetermined combustion time CT₁Has passed
Later, time T_Four, One burner 10A₁-10D
₁Of the other burner 1 is closed.
0A _Two-10D_TwoFuel cutoff valve 13b and air cutoff valve 2
With 1b closed, the combustion state and heat storage of all burners
Stop the state.

[0039] Then, after providing downtime RT ₁ in a short time like the time described above, at time T _5, one of the burners 10A ₁ ~10D ₁ the combustion state, the other burner 10
Switch the A ₂ ~10D ₂ to the heat storage state. After the predetermined burn time CT ₁ has elapsed, to stop the combustion state and the heat storage state of all the burners at time T _6. Hereinafter, likewise, it repeats the same cycle and the time point T ₃ later.

[0040] In the combustion switching time over chart of FIG. 4 described above, all of the regenerative burner device 6A~6D the same pause time (operation pause time) RT ₁ and combustion time (real burn time) Combustion switching provided CT ₁ It was carried out, moreover, downtime RT ₁ in one cycle YT ₁ set short, since the longer the burning time CT ₁ of all regenerative burner device 6A-6D, as shown by the solid line in FIG. 7 , The transport path position L _{1 on} the downstream side 31 a, the transport path position L ₄ on the upstream side 31 b, and even the transport path positions L ₂ and L ₃ between these positions L ₁ and L _2. Temperature in the furnace. This makes it possible to set the required furnace temperature where the temperature distribution in the furnace length direction is uniform and high.

FIG. 5 shows the downstream side 31 of the first heating zone 3.
a must be in a high temperature state and the upstream side must be in a low temperature state.
The fuel of the regenerative burner devices 6A to 6D for setting the temperature in the furnace required
FIG. 3 is a time chart showing a changeover time of a sintering operation._TenTo
Then, one burner 10A ₁-10D₁The combustion state and
And the other burner 10A_Two-10D_TwoIn the heat storage state
You.

[0042] Then, at time T _11, to stop all combustion state and the heat storage state of the burner 10A ₁ ~10D _1. Then, the time T at which the short pause time RT ₂ elapses
_{In FIG. 12} , one of the burners 10A ₁ and 10B ₁ of the regenerative burner devices 6A and 6B is in a heat storage state, and the other burner 10A
₂ and 10B ₂ are set to the combustion state. Then, after a predetermined burning time CT ₂ has elapsed, at time T _13, the burner 10
The combustion state and the heat storage state of A ₁ , 10A ₂ , 10B ₁ , and 10B ₂ are stopped. Then, after providing a dwell time RT ₂ of short like the time I described above, at time T _14, one of the burners 10A _1, 10B ₁ the combustion state, the other 10
A ₂ and 10B ₂ are switched to the heat storage state. Then, after a predetermined burning time CT ₂ has elapsed, to stop the combustion state and the heat storage state of all the burners at time T _15. Hereinafter, similarly, at the time T ₁₆ to pause time RT ₂ has passed for a short time, repeats the same cycle and the time point T ₁₂ later.

On the other hand, the regenerative burner devices 6C and 6D
Point T₁₁Relatively long pause time RT _ThreeTime T
₁₇At one burner 10C₁, 10D₁The heat storage
State, the other burner 10C_Two, 10D_TwoTo the combustion state
You. Next, the combustion time C of the regenerative burner devices 6A and 6B
T_TwoShorter predetermined combustion time CT_ThreeAfter the time elapses,
T₁₈In the burner 10C₁, 10C_Two, 10D₁,
10D_TwoThe combustion state and the heat storage state are stopped. And
Relatively long pause time RT similar to the time described above_ThreeProvided
After time T₁₉At one burner 10C₁, 10
C₁The combustion state, the other 10C_Two, 10C_TwoThe heat storage state
Switch to. Then, a predetermined combustion time CT _ThreeHas passed
Later, time T₂₀State and heat storage of all burners
Stop the state. Hereinafter, similarly, the relatively long pause time R
T_ThreeTime T_{twenty one}At time T₁₇As above
Is repeated.

In the combustion switching time chart of FIG. 5 described above, the regenerative burner devices 6A and 6B disposed on the downstream side 31a of the first heating zone 3 and the regenerative burner devices 6C and 6D disposed on the upstream side 31b. Are the combustion switching cycles in which the pause time and the combustion time are different, and the regenerative burner devices 6A and 6B
Time (operation pause time) RT during one cycle YT _2
2 is set short, the combustion time (effective combustion time) CT ₂ is set long, and the regenerative burner devices 6C, 6D
1 cycle YT ₃ in the rest time of the (operating pause time) RT
₃ sets a longer combustion time (real burn time) since the shorter the CT _3, as indicated by a chain line in FIG 7, the conveying path position L ₁ in the furnace temperature at the downstream side 31a is high, upstream furnace temperature is lowered toward the transport path position L ₄ of the side 31b. Thereby, it is possible to set the required furnace temperature in which the temperature distribution in the furnace length direction is inclined downward in the direction of travel of the slab S.

FIG. 6 shows the downstream side 31 of the first heating zone 3.
a is a low temperature state, the upstream side is intended to indicate a combustion changeover time over chart of regenerative burner device 6A~6D to set the required oven temperature such that high temperature state, at time T _20, all regenerative burner device one of the burners 10A ₁ ~10D ₁ and the combustion state of 6A-6D, the other of the burner 10A ₂ ~10D ₂ and the heat storage state.

[0046] Then, at time T _21, to stop all combustion state and the heat storage state of the burner 10A ₁ ~10D _1. At a time T ₂₂ to a relatively long dwell time RT ₄ has elapsed, regenerative burner devices 6A, one of the burners 10A _1, 10B ₁ the heat accumulation state of 6B, the other burner 10
A ₂ and 10B ₂ are set to the combustion state. Then, after a predetermined burning time CT ₄ has elapsed, at time T _23, the burner 1
_{0A 1, 10A 2, 10B 1} , and stops the combustion state and the heat storage state of 10B _2. Then, after providing the RT ₄ relatively long dwell time in the same manner and time as described above, at time T _24, one of the burners 10A _1, 10B ₁ the combustion state, switches the other 10A _2, 10B ₂ in the heat storage state. And
After a predetermined burning time CT ₄ has elapsed, to stop the combustion state and the heat storage state of all the burners at time T _25. Hereinafter, similarly, the time T when the short pause time RT ₄ has elapsed
In _26, repeating the same cycle and the time point T ₂₂ later.

On the other hand, the regenerative burner devices 6C and 6D
Point T_{twenty one}Short pause RT from_FiveTime T₂₇
At one burner 10C₁, 10D₁The heat storage
State, the other burner 10C_Two, 10D_TwoTo the combustion state
You. Next, the combustion time C of the regenerative burner devices 6A and 6B
T_FourLonger predetermined combustion time CT_FiveAfter the time elapses,
T ₂₈In the burner 10C₁, 10C_Two, 10D₁,
10D_TwoThe combustion state and the heat storage state are stopped. And
Short pause time RT similar to the above-mentioned time_FiveEstablished
Later, time T₂₉At one burner 10C₁, 10C
₁The combustion state, the other 10C_Two, 10C_TwoTo heat storage
Switch. Then, a predetermined combustion time CT_FiveHas passed
Later, time T₃₀State and heat storage of all burners
Stop the state. Hereinafter, similarly, the short pause time RT
_FiveTime T₃₁At time T ₂₇Similar to the following
Repeat the cycle.

In the combustion switching time chart of FIG. 6 described above, the regenerative burner devices 6A and 6B disposed on the downstream side 31a of the first heating zone 3 and the regenerative burner devices 6C and 6D disposed on the upstream side 31b. Are the combustion switching cycles in which the pause time and the combustion time are different, and the regenerative burner devices 6A and 6B
1 cycle YT ₄ in the rest time of the (operating pause time) RT
₄ is set long, the combustion time (effective combustion time) CT ₄ is set short, and the regenerative burner devices 6C, 6D
1 cycle YT pause time of ₅ in (operating pause time) RT
₅ is set short, since the set burning time (real burn time) CT ₅ long, as indicated by the two-dot chain line in FIG. 7, the downstream side 31a transportation path position L ₁ in the furnace temperature is low, the furnace temperature toward the conveying path position L ₄ upstream 31b is gradually increased. Thereby, it is possible to set a required furnace temperature in which the temperature distribution in the furnace length direction is inclined upward in the traveling direction of the slab S.

Therefore, in the present embodiment, the four regenerative burner devices 6A to 6D installed at predetermined intervals along the transport path 31 are connected to the pair of burners 10A ₁ , 10A.
Simply by changing the substantial burning time per unit time A ₂ ~10D _1, 10D _2, carrying amount of the slab S, the conveying speed,
According to the heating amount of the slab S, the temperature distribution in the longitudinal direction (furnace length direction) of the transport path 31 can be attached with high accuracy by increasing the control response.

Further, in the present embodiment, only the long or short pause times RT _{1 to} RT ₅ are provided.
A pair of burners 10 of four regenerative burner devices 6A to 6D
A _1, 10A ₂ ~10D _1, the 10D ₂ substantially burn time C
Since setting the T ₁ to CT _5, special adjustment valves and piping for supplying and stopping of the fuel is not required, it is possible to provide an inexpensive furnace temperature control system.

In the above embodiment, the case where four regenerative burner devices 6A to 6D are provided in the first heating zone 3 has been described.
Even when a plurality of regenerative burners controlled by C29 are installed, the same function and effect can be obtained. Further, the number of regenerative burners is not limited to the above-mentioned number, and the same effect can be obtained even if the number is larger.

Although the case where M gas is used as the fuel supplied to the burners 10a and 10b has been described, the present invention is not limited to this, and other fuel gases and liquid fuels such as heavy oil can be applied. .

Further, the combustion switching control of this embodiment is performed by DDC.
Although the description has been given of the case where the processing is performed in step 29, the present invention is not limited to this, and the sequence may be controlled by another programmable controller, a sequence control circuit, or the like.

Further, the supply of combustion air to the burners 10a and 10b and the discharge of waste gas are controlled by individual air shutoff valves 21.
Although the description has been given of the case where the switching is performed by the a and 21b and the waste gas cutoff valves 24a and 24b, the invention is not limited thereto, and the switching mechanism may be configured by using a direction switching valve that switches the flow path by an air cylinder or the like.

Further, in each of the above embodiments,
Although the case where the present invention is applied to a continuous heating furnace has been described, the present invention is not limited to this, and can be applied to other heating furnaces, heat treatment furnaces, and the like.

[0056]

As described above, the method of controlling the temperature of the continuous heating furnace according to the first aspect of the present invention provides a method of controlling the temperature of the continuous heating furnace in which, when the temperature inside the furnace is kept constant, a pair of the regenerative burner devices of all the sets is used. Switching combustion is performed in a state where the burners are set such that the actual combustion times per unit time are all the same. As a result, the heating amounts of all the regenerative burners installed at predetermined intervals in the furnace length direction in the furnace become the same. The temperature distribution in the furnace length direction up to the outlet side in the furnace where the gas is carried out can be made uniform.

When the furnace temperature on the inlet side of the furnace is set high and the furnace temperature on the outlet side of the furnace is set low, the regenerative burner device installed on the inlet side of the furnace may be used. The pair of burners are set to have a substantial combustion time for a long time, and the pair of burners of a regenerative burner device installed on the outlet side in the furnace are set to have a substantial combustion time for a short time to perform switching combustion. As a result, the heating amount of the regenerative burner device on the inlet side in the furnace increases, and the heating amount of the regenerative burner device on the outlet side in the furnace decreases. Can be set in a state where the temperature distribution in the furnace length direction is inclined downward.

Further, when the temperature in the furnace on the inlet side of the furnace is set low and the temperature in the furnace on the outlet side of the furnace is set high, the regenerative burner device installed on the inlet side in the furnace may be used. The combustion is switched by setting the pair of burners to a short combustion time and setting the pair of burners of the regenerative burner device installed on the outlet side in the furnace to a long combustion time. As a result, the heating amount of the regenerative burner device on the inlet side in the furnace decreases, and the heating amount of the regenerative burner device on the outlet side in the furnace increases, so that from the inlet side in the furnace to the outlet side in the furnace. Can be set in a state where the temperature distribution in the furnace length direction is inclined upward.

As described above, according to the present invention, a plurality of sets of regenerative burners installed at predetermined intervals in the furnace length direction in the furnace change the actual combustion time per unit time of the pair of burners. Because it is only a method,
The temperature distribution in the furnace length direction can be provided with high control responsiveness and high accuracy according to the transport speed, the heating amount of the object to be heated, and the like.

According to the second aspect of the invention, the effect of the method of controlling the temperature of the continuous heating furnace according to the first aspect can be obtained, and each operation can be performed simply by providing a long or short operation downtime. Since the actual combustion time is set for each pair of burners, a special adjusting valve and a piping system for supplying and stopping the fuel are not required, and an inexpensive furnace temperature control system can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a continuous heating furnace according to the present invention.

FIG. 2 is a schematic configuration diagram showing a plurality of sets of regenerative burners according to the present invention.

FIG. 3 is a plan view showing a pair of burners and a heat storage body of a plurality of sets of regenerative burners installed in a heating path.

FIG. 4 is a time chart of a first example showing switching combustion timings of a plurality of sets of regenerative burners according to the present invention.

FIG. 5 is a time chart of a second example showing switching combustion timings of a plurality of sets of regenerative burners according to the present invention.

FIG. 6 is a time chart of a third example showing switching combustion timing of a plurality of sets of regenerative burners according to the present invention.

FIG. 7 is a chart showing a temperature distribution in the furnace length direction in the furnace set by the switching combustion timing shown in the first to third time charts.

[Explanation of symbols]

1 continuous heating passage 3 first heating zone (furnace) 6A-6D regenerative burner device _{10A 1, 10A 2 ~10D 1,} 10D 2 burners 20a, 20b regenerator CT ₁ to CT ₅ burn time (real burn time) RT ₁ to RT ₅ rest time (operation pause time) S slab (object to be heated) YT ₁ ~YT ₅ switching the combustion cycle

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoji Fujimoto 1-chome, Mizushima-Kawasaki-dori, Kurashiki-shi, Okayama Pref. Chome (without address) Mizushima Works, Kawasaki Steel Corporation (72) Inventor Kazuhiro Yahiro 1-chome, Mizushima, Kawasaki-dori, Kurashiki City, Okayama Prefecture (without address) Inside Mizushima Works, Kawasaki Steel Corporation

Claims (2)

[Claims] 1. The furnace is heated to a predetermined furnace temperature, and a heated object continuously carried in from the inlet side of the furnace is conveyed at a predetermined speed in a furnace length direction in the furnace. In a continuous heating furnace that heats while moving to the outlet side, a regenerative burner device having a pair of burners and a heat storage body connected to these burners is provided at predetermined intervals in the furnace length direction in the furnace. A plurality of sets are installed, and a combustion burner that performs a combustion operation by supplying combustion air that has passed through the regenerator to a pair of burners of each regenerative burner device, and an exhaust gas in a furnace passes through the regenerator. In addition to performing combustion control to alternately switch the non-burning burner performing a heat storage operation at predetermined time intervals and performing a combustion operation by alternately switching the pair of burners, the actual combustion time per unit time for each group is set. Set for each pair of burners, Furnace temperature control for a continuous heating furnace, characterized in that by performing switching combustion control of each pair of burners based on the combustion time, the inside of the furnace is heated with a temperature distribution in the furnace length direction. Method. 2. In one cycle in which each pair of burners alternately switches from a combustion operation to a heat storage operation and from a heat storage operation to a combustion operation, an operation pause time is provided for suspending all the combustion operation and the heat storage operation. 2. The furnace temperature control method for a continuous heating furnace according to claim 1, wherein the substantial combustion time is set for each pair of burners in each set by setting the operation suspension time to a long time or a short time.