JPH075981B2 - Side burner combustion control method for continuous heating furnace - Google Patents

Description

TECHNICAL FIELD The present invention relates to a side burner combustion control method for a continuous heating furnace. More specifically, the present invention relates to a side burner combustion control method for uniformizing the temperature distribution in a continuous heating furnace.

[Conventional technology]

Generally, in a heating furnace using a burner, the flame length fluctuates due to the fluctuation of the heat input amount of the burner. Therefore, in a side-type heating furnace having a side burner, fluctuations in heat load (in / out of heated material) and changes in heat input (fuel supply)
Particularly, temperature unevenness easily occurs in the width direction of the material to be heated, which is a major problem in quality control and energy saving measures.

Therefore, as a method for dealing with the problem of temperature unevenness in the furnace width direction in this side type heating furnace, there is a method of using a burner arrangement other than the side burner. As one of the methods, for example, there is a method of using a ceiling burner, but since this method increases the number of burners, the structure becomes complicated and it is difficult to balance each burner with other burners, In addition, there are many problems due to the large amount of radiated heat and the fact that it does not save energy. As another method, there is a method of using an axial flow burner, but in this method as well, it is necessary to lower the ceiling of the burner arrangement part due to the structure, so that the heating capacity is reduced, and the semi-batch In the case of performing a regular operation, it is not possible to supply sufficient heat to the material to be heated stopped immediately below the burner installation portion, resulting in uneven temperature and other problems.

By the way, regarding the above-mentioned structural problem of the burner, that is, with respect to the problem that the flame length fluctuates due to the fluctuation of the heat input amount of the burner, by changing the flow rate ratio of the internal flow and the external flow of the fuel gas in the burner, the flame length, A burner combustion method that can change the flame temperature and flame temperature distribution was found.
That is, as shown in FIG. 4, the burner 5 is provided with the inflow fuel supply pipe 19 and the outflow fuel supply pipe 20, and the flame length is controlled by controlling the ratio of the fuel amounts supplied to the supply pipes 19 and 20. Fifth
This is a combustion method that converges to the shaded area shown in the figure. In FIG. 5, the horizontal axis shows the heat input required for one burner, and the vertical axis shows the flame length. For example, heat input (indicated value) q
When q exceeds q ₂ , the inner / outer flow rate ratio is set to 0/100,
When the external flow is 100%, the actual heat input amount is controlled by the amount of fuel given to the external flow fuel supply pipe 20. In the range where the heat input amount (indicated value) q exceeds q ₁ and is less than q ₂ , the internal / external flow rate ratio is set to 50/50, and the actual heat input amount is given to the internal fuel supply pipe 19 and the external fuel supply pipe 20. Are controlled in a manner that the relative ratio is maintained at 50/50.
The heat input range (indicated value) q is q ₁ below, the inner / outer flow ratio as 100/0, an inner flow of 100%, is controlled by the amount of fuel to provide the actual heat input to the inner flow fuel supply pipe 19.

By using this burner combustion method, the flame length of the burner can be kept approximately constant even if the heat input (indicated value) of the burner fluctuates, so even in the heating path using the side burner, the furnace width The temperature distribution in the direction can be kept substantially constant, and the temperature distribution in the furnace width direction of the object to be heated can be made substantially constant.

[Problems to be solved by the invention]

However, in the case of using the burner combustion method described above, by changing the flow rate ratio of the internal flow and the external flow of the fuel gas in the burner, the flame length can be maintained substantially constant regardless of the heat input amount. Rate 30% (burner 1
In the range of q ₀ ) or more per piece, and in the range of the combustion load factor of less than 30%, the flame length cannot be kept substantially constant, and the flame length sharply decreases. For example, in a flame ₆₁ of a predetermined length as shown in the Figure 12 in the combustion load factor of 30% or more (a), the
When the temperature distribution in the furnace width direction becomes relatively flat as shown by I in Fig. 12 (b) and the combustion load factor is extremely low at less than 30%, it is shown in Fig. 12 (a). A short flame 6 ₂
As shown in II of FIG. 12 (b), the temperature distribution in the furnace width direction has large fluctuations.

Therefore, in a side-type heating furnace having a side burner, even when using the combustion method of the burner for changing the flow rate of the internal flow and the external flow of the fuel gas in the burner, in the range of the combustion load factor less than 30%, The flame length cannot be kept almost constant, and at that time, the flame length decreases rapidly, so the furnace temperature in the center of the furnace width direction drops, and the furnace temperature distribution becomes concave, and the heated material cannot be heated uniformly. Is occurring.

Therefore, the object of the present invention, in the continuous heating furnace having a side burner, the combustion load factor is, for example, less than 30%, even in a low range, uniform furnace temperature distribution in the furnace width direction, To make the temperature distribution uniform.

[Means for solving problems]

In the present invention in order to achieve the above object, a heat input Qc instructed to continuous heating furnace, of each side burner the heating furnace, a minimum heat input q to the heating furnace at the set minimum flame length F _{L From 0} , the number n of side burners that can be assigned to combustion at the set minimum flame length _FL or more in the relation of (n + 1) · q ₀ > Qc ≧ n · q ₀ is calculated; n is equal to the total number N of side burners. When n is smaller than the total number N of side burners, n side burners are assigned to combustion, N−n side burners are assigned to non-combustion, and n side burner positions are assigned to combustion. Are sequentially moved in the side burner arrangement direction at predetermined time intervals.

[Action]

According to this, all the side burners assigned to combustion burn with a flame length of the set minimum flame length _FL or more, so the temperature distribution in the furnace width direction becomes uniform, and only the specific side burner is used. Is not fixed to combustion and the other is not fixed to non-combustion, that is, each burner is switched between combustion and non-combustion at predetermined time intervals, so that the temperature distribution in the furnace length direction is also uniform. Nevertheless, the heat input of the entire furnace can be controlled to the instructed heat input Qc.

In a preferred embodiment of the present invention, in order to uniformly and simply control the combustion / non-combustion of each burner, and in order to enhance the time-series uniformity of the temperature distribution in the furnace length direction, When the number n of side burners to be made is smaller than the total number N of side burners, switching from combustion to non-combustion and vice versa is sequentially moved in the arrangement direction of the side burners at the predetermined time intervals.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

〔Example〕

FIG. 1 shows an example of a continuous heating furnace for carrying out the side burner combustion control method of the present invention, and FIG. 2 shows a cross section taken along line II-II of the continuous heating furnace shown in FIG. FIG. 3 shows a cross section taken along line III-III of one zone of the continuous heating furnace shown in FIG.
In these figures, 1 is a pass line, 2 is a material to be heated,
3 is a furnace body, 4 is a heating space, 5 is a burner (side burner) provided on the side surface of the furnace body 3, 6 is a flame emitted from the burner 5, 7 is a partition wall, 8 is a side wall, and 90 is the furnace to be heated. It is an extraction port for extracting wood.

The material to be heated 2 placed on a skid (not shown) is transferred through the pass line 1 in the furnace toward the extraction port 90.
The furnace body 3 is divided into a plurality of zones by the partition wall 7,
The combustion control of the burner 5 in each zone is performed for each zone. That is, the furnace temperature control is performed for each zone.

Referring to FIG. 3, there are three pairs of side burners 5 (A to F) in one zone, and these are burner-controlled in burner pair units.

FIG. 4 shows a sectional view of a side burner used in this continuous heating furnace. Here, 5 is a burner body, 18 is an inlet for combustion air, 19 is an inflow fuel supply pipe, 20 is an outflow fuel supply pipe, and 21 is a burner tile. The burner 5 is designed so that the fuel gas is separately flown into the inflow fuel supply pipe 19 and the outflow fuel supply pipe 20, and the flow rate ratio of the fuel gas flowing from the supply pipes 19 and 20 is changed. Thus, the characteristics of flame length, fire temperature, and flame temperature distribution can be changed. The characteristic is, for example, as shown in FIG. 5, and shows the relationship between the heat input amount (combustion amount) and the burner flame length when the flow rate ratio of the internal flow and the external flow of the fuel gas is changed. . In this way, when the heat input amount q is given, the burner flame length can be changed by changing the flow rate ratio between the internal flow and the external flow of the fuel gas, and the flow ratio between the internal flow and the external flow of the fuel gas can be changed. By changing the combustion amount, combustion control can be performed so that the burner flame length is kept substantially constant even if the heat input amount q is changed. Therefore, the burner shown in FIG. 4 is used as a side burner of the heating furnace, and the burner flame length is changed in the heating furnace by changing the flow rate ratio of the internal flow and the external flow of the fuel gas according to the given heat input amount q. Combustion can be controlled so as to fall within the required predetermined length range, and the flame can reach the central portion of the heating furnace. Thereby, the temperature distribution in the furnace width direction can be kept substantially constant.

FIG. 6 is a system block diagram showing an arrangement of three pairs of burners and valves in one zone of the heating furnace, and a schematic configuration of an electric system for controlling combustion of the three pairs of burners. In FIG. 6, 9 is a flow rate control valve, 13 and 14 and 15 are electromagnetic on-off valves, and 16 ₁₁ and 16 ₁₂ are the first pair which face each other.
A flow ratio control valve for setting the respective inner / outer flow ratios of the pair of side burners A and B, 16 ₂₁ and 16 ₂₂ are inside of each of the second pair of side burners C and D that face each other. Flow rate adjusting valve for setting the / outside flow ratio, 16 ₃₁ and 16 ₃₂ are flow rate adjusting for setting the in / outside flow rate ratio of each of the third pair of side burners E, F which face each other. It is a valve. First pair A,
The burners 5 of B, the second pair C, D, and the third pair E, F are controlled as one unit for each pair.

In the side burner combustion control method for the continuous heating furnace according to the embodiment of the present invention, the combustion control is performed in upper and lower units (3 pairs in each unit) of one zone, and therefore, for example, 3 pairs (total number N in FIG. 6). = 6, total logarithm N ₁ = 3) given the heat input Qc ₁ (indicated value) in burner units, this and the input flame that brings the required flame length _FL (Fig. 5) of one side burner Heat quantity q ₀ (5th
Figures), the maximum logarithm of burners for burning at the required flame length F _L
Calculate n ₁ as follows.

2 · (n ₁ +1) · q ₀ > Qc ₁ ≧ 2n ₁ · q _{0 In} general, this is the total number of burners N, the number of combustion burners n,
When expressed by the required heat input amount Qc, (n + 1) · q ₀ > Qc ≧ n · q ₀ N ≧ n. Then, the opening degree of the fuel control valve 9 is set to the opening degree Ps for supplying the fuel corresponding to Qc ₁ , and the n ₁ pairs of burners are turned on (combustion: fuel supply) by opening / closing the electromagnetic opening / closing valves 13 to 15. N
₁ (= 3) -n ₁ pair of burner off (non-combustion: fuel cutoff)
The burners of each pair are switched on and off in the pattern shown in FIG. Incidentally, in FIG. 9, the mark .largecircle. Is on and the mark x is off, and in this embodiment, switching is performed in a cycle of 5 minutes. It takes a few seconds to a minute for the fire to stabilize for a certain length after switching from off to on. Therefore, the switching cycle needs to be 1 minute or more. The upper limit of this cycle is determined by the in-furnace conveying speed of the material to be heated, the heat load changing cycle, and the like.

When the logarithm of burner on n ₁ is set in this way, the heat input q per on-burner is q ₁ (Fig. 5) or less, or exceeds q ₁ q ₂
It is determined whether the flow rate is less than or equal to q ₂ or more, and the inner / outer flow rate ratio is determined according to the determination result, and the flow rate ratio control valves 16 _{11 to} 16 ₃₂ are set to have this flow rate ratio.

In this embodiment, the burners A to F all have the same structure and dimensions, the solenoid on-off valves 13 to 14 all have the same structure and dimensions, and the flow ratio control valves 16 _{11 to} 16 ₃₂ also have the same structure and dimensions. Therefore, the fuel corresponding to the heat input Qc ₁ is supplied to all the burners set to ON (combustion) through one flow control valve 9, so that the burners set to ON are equal to each other, and Qc ₁ Fuel corresponding to / 2n ₁ (heat input unit) is supplied. Then, as described above, the inside / outside flow rate ratio of each burner set to ON is set to the set predetermined length _FL.
It is set to bring about the above flame length. As a result, the flame length of each burner set to ON becomes the shaded area shown in FIG.

FIG. 7 and FIG. 8 show characteristic diagrams when such combustion control is performed. That is, FIG. 7 shows the relationship between the T / D ratio (combustion load factor) and the number of combustion burners per upper section of one zone of the heating furnace, and FIG.
T / D ratio (combustion load factor) and burner 1 per zone upper zone
The relationship of T / D ratio (combustion load factor) per book is shown. In each of these zones, the number of combustion burners changes in one zone of the heating furnace due to changes in the combustion load rate, and as a result, the combustion load rate per burner also changes, so the combustion load rate per low zone is 10 to 30. %, The operation can be performed without lowering the combustion load rate per burner.

As shown in Fig. 10a, conventionally, the temperature in the center of the furnace width direction drops significantly when the load factor of the entire heating furnace (or the entire zone) is 20%, but by controlling as described above, the temperature is shown in Fig. 10b. Thus, even if the load factor is 20%, the temperature distribution will be uniform.
That is, the uniformity of the temperature distribution is high even at a low load factor.

Referring again to FIG. 6, the flow rate adjusting valve 9 is a speed reducer 10 that rotationally drives the valve body that sets the flow rate, a motor 11 that drives the speed reducer 10, and an angle sensor that generates an electrical signal corresponding to the rotation angle of the valve body. The motor 11 is provided with 12, and the motor 11 is rotationally biased by the positioning driver 22, and the detection signal of the angle sensor 12 is given to the driver 22. Driver 22 is a microprocessor
The opening data Ps given from 33 is converted into an analog signal, and this is compared with the detection signal of the angle sensor 12 so that the opening of the control valve 9 becomes the instructed opening (Ps).
The valve 11 is rotationally biased to set the opening of the control valve 9 to the indicated value.

Each of the solenoid on-off valves 13-15 has a valve driver 23-25
It is energized by each of. Driver 23 is a valve when the instruction signal 0C ₁ of the microprocessor 33 is H (high level) 15
Open and close at L. Microprocessor
33 driver 24 when an instruction signal 0C ₂ is H (high level) of
Opens the valve 14 and closes the valve when L. Instruction signal 0C ₃ of the microprocessor 33 to the driver 25 the valve 13 when the H (high level) in the open and the closed when the L.

The flow rate adjusting valve 16 ₃₁ is a speed reducer 17 that rotationally drives the valve body that sets the flow rate ratio, a motor 20M that drives the reducer 17, and an angle sensor 20S that generates an electrical signal corresponding to the rotation angle (flow rate ratio) of the valve body. The motor 20M is urged to rotate by the positioning driver 26, and the detection signal of the angle sensor 20S is transmitted to the driver 26M.
Given to. The driver 26 converts the opening ratio data Pb given from the microprocessor 33 into an analog signal,
And butted to a detection signal which the angle sensor 20S, the flow ratio control valve 16 ₃₁ opening ratio (inner / outer flow ratio) rotating energizing the motor 20M so is opening ratio indicated (Pb) Then, the opening ratio of the flow ratio control valve 16 ₃₁ is set to the indicated value.

The flow rate control valves 16 _{11 to} 16 ₂₂ and 16 ₃₂ have the same structure as 16 ₃₁ and the positioning drivers 27 to 31 have the same structure as 26 and operate in the same manner.

Opening instruction data Ps, on / off instruction signal 0C ₁ ~0C ₃ and opening ratio indicator data Pb are such Fuotokapura via Interferon chair 32 comprising signal transmission means which are insulated, the driver from the microprocessor 33 Given to 22-31. Through the interface 32 to the microprocessor 33, the heat input instruction data Qc of the six pairs of burners A to F assigned
₁ and start signal ST are given.

Each of the burners A to F is equipped with a pilot burner, and the pilot burners of all burners are ignited at the start of the heating furnace operation, and the pilot burners are constantly ignited continuously until the heating furnace operation is stopped.

11a to 11c show the combustion control operation of the burners A to F of the microprocessor 33. First, refer to FIG. 11a. When the power is turned on, the microprocessor 33 turns on / off.
Initialize output ports and clear internal registers, counters, timers, flags, etc. (Step 1: The word step in parentheses is omitted below). The initialization (1), Ps = 0 (closing _{command), 0C 1 ~0C 3 = L} ( closing command) and Pb = 0 (inner / outer flow ratio = 0/100), respectively the driver 22, the driver 23 ~ 25 and given to the driver 26-31. Immediately after the power is turned on, the pilot burners of all the burners A to F are ignited, but since the flow rate control valve 9 and the electromagnetic opening / closing valves 13 to 15 are closed by the initialization (1), the burners A to F ( The main flame) does not ignite (combust).

When the initialization is completed, the microprocessor 33 waits until the start signal ST becomes H (control instruction) (2). When it becomes H, first, the T timer (program timer) is set in order to determine the repetition cycle of the control operation (3). Then, the heat input data Qc ₁ is read (4). Heat input data Qc ₁ is
It is provided by a host computer that controls the entire heating furnace (Fig. 1). Next, the opening Ps of the regulating valve 9 corresponding to the heat input Qc ₁ is calculated, and the data indicating Ps is output to the driver 22 (latched to the output port) (6). Thereby, the opening degree of the adjusting valve 9 becomes
The opening is the fuel flow rate that brings the heat input of Qc ₁ into the heating furnace. However, at this stage, all the solenoid on-off valves 13 to 15 are closed, and fuel is not supplied to the burners A to F.

Then the micro-processor 33, converts the amount of heat input Qc ₁ I read heat input Qc _1/6 per one burner, which is compared with the heat input q ₀ which results in setting minimum flame length F _L (7 ). If it is the amount of heat input Qc _1/6 per one burner set minimum flame length F _L of the results heat input q ₀ or more, since it can be burned the entire burner A~F at the set minimum flame length F _L or more, in this case All burners (3
In order to set data indicating that (pair) is set to combustion, 3 is set in the register N ₁ (8). The heat input Qc _1/6 per one burner, as compared with the inner / outer flow ratio minimum heat input q ₂ per one burner capable of operating at 0/100 (9), Qc
When _1/6 exceeds the q _2, it is possible to operate at a flow rate ratio of 0/100, the inner / outer flow ratio of the corresponding 0/100, data indicating the opening ratio Pb
Is output to the drivers 26 to 31 (set to the output port) (10). Then, all the solenoid on-off valves 13 to 15 are opened (14). As a result, all the burners A to F ignite (combust) at a flow rate ratio of 0/100. This is the heat input per burner
The combustion setting is in the range exceeding q ₂ (Fig. 5). With this setting, it is checked whether or not the T timer has timed out (15), and if the T timer has not timed out, it is checked whether or not the start signal ST is at L (operation stop). If the T timer times out without becoming L, the process returns to step 3 and proceeds to step 3 and the subsequent steps. The control operation described above, the amount of heat input Qc _1/6 per one burner q ₂
During this period, all burners A to F are operated at a flow rate ratio of 0/100.

The amount of heat input Qc _1/6 per one burner is a q ₀ or more but, Qc ₁
/ 6 when the ≦ q _2, comparing Qc _1/6 q ₁ and (Figure 5) (1
1). Qc _1/6> If it is q _1, input of one per burner heat q =
Qc _1/6 is beyond q _1, because it is q ₂ the range, the inner / outer flow ratio to 50/50, the opening ratio corresponding to 50/50 Pb
Is calculated and the data indicating this is output to the drivers 26 to 31 (set to the output port) (12). And solenoid on-off valve
Open all 13 to 15 (14). As a result, all burners A to F are ignited (combusted) at a flow rate ratio of 50/50.

The amount of heat input Qc _1/6 per one burner is a q ₀ or more but, Qc ₁
When / 6 ≦ q ₁ , the opening ratio Pb corresponding to 100/0 is calculated in order to set the internal / external flow ratio to 100/0, and the data indicating this is output to the drivers 26 to 31 (output port Set) (13). Then, all the solenoid on-off valves 13 to 15 are opened (14). As a result, all burners A to F are ignited (combusted) at a flow rate ratio of 100/0.

Or heat input Qc _1/6 per one burner is a combustion control when more than q _0.

As long as _{Qc 1/6> q 0,} 3 pairs of burners A~F burns continuously in "all burner combustion pattern" shown in Figure 9. Incidentally, when Qc ₁ is changed within the range of Qc _1/6> q _0, at step 9-13, when the Qc _1/6> q ₂ is within the burner / outer flow ratio of 0/100, the 50/50 when _{q 1 <Qc 1/6 ≦} q 2,
Also set to 100/0 when the Qc _1/6 ≦ q _1.

3 when the burner per heat input Qc _1/6 of the pair is less than q _0, the process proceeds from step 7 18, the amount of heat input Qc per one burner for allocating Qc ₁ to 2 to the burner ₁ / Compare 4 with q ₀ (18). That is, if the number of combustion burners is limited to two, it is determined whether or not operation can be performed with the minimum flame length _FL or more.
When the amount of heat input Qc _1/4 per one burner for allocating Qc ₁ to 2 pairs of burners are q ₀ or more, that is, Qc _1/6 <q ₀
When ≦ Qc _1/4, the set of two pairs of burners minimum flame length F _L
Since it is possible to burn the above, in this case, in order to set the data indicating that two pairs of burners are set to burn, set register N ₁ to 2 (20), set a 5 minute timer (21), Set register M to 1 (22) and 0C ₁ = L
(Valve 15 closed), 0C _2, 0C ₃ = setting the H (valve 14, 13 open) (23). Then, the amount of heat input Qc _1/4 per one burner, as compared with the inner / outer flow ratio minimum heat input q ₂ per one burner capable of operating at _{0/100 (24), Qc 1/} 4 is q _If it exceeds ₂ , it can be operated at a flow rate ratio of 0/100, so the data Pb indicating the opening ratio corresponding to the inner / outer flow rate ratio of 0/100 is output to the drivers 26 to 31 (set to the output port) ( twenty five). As a result, the two pairs of burners C to F ignite (combust) at a flow rate ratio of 0/100.

Heat input Qc per one burner _1/4 is a q ₀ or more but, Qc ₁
/ 4 at ≦ q ₂ compares the Qc _1/4 q ₁ and (Figure 5) (2
6). Qc _1/4> If it is q _1, input of one per burner heat q =
Qc _1/4 is, exceed q _1, because it is q ₂ the range, the inner / outer flow ratio to 50/50, the opening ratio corresponding to 50/50 Pb
Is calculated and the data indicating this is output (set to the output port) to the drivers 26 to 31 (27). As a result, the two pairs of burners C to F ignite (combust) at a flow rate ratio of 50/50.

Heat input Qc per one burner _1/4 is a q ₀ or more but, Qc ₁
When / 4 ≤ q ₁ , the opening ratio Pb corresponding to 100/0 is calculated in order to set the internal / external flow rate ratio to 100/0, and the data indicating this is output to the drivers 26 to 31 (output port Set) (28). As a result, the two pairs of burners C to F have a flow ratio of 10
Ignite (burn) at 0/0.

The flow advances to 15 from step 25, 27 or 28, where waiting for the time-over of the T type, also proceeds to step 3-6, if _{Qc 1/6 <q 0 ≦} Qc 1/4 is continuing, Every time the time value T of the T timer is reached, proceed to step 7-18-19 and step
In 19, the register N ₁ is set to 2, so the 11th
b Go to step 29 in the figure. In step 29, it is checked whether the 5-minute timer is over, and if not, step 25, 27 or 28 is executed, the process returns from step 15 to step 3, and this is repeated in the T cycle. 5 in step 29
If the minute timer has timed out, the 5 minute timer is reset (30) and the contents of register M are referenced (31,3).
Four). When the content of the register M is 1, this means that the burners C to F are currently on (combustion) and the burners A and B are off (fire extinguishing).
2 indicates that burners A, B, E and F are currently set to on (combustion) and burners C and D are set to off (extinguishing) 3 This means that the burners A to D are currently set to on (combustion) and the burners E and F are set to off (extinguishing). Therefore, if the content of the register M is 1 (burners C to F on, burners A and B off continued for 5 minutes), then the burners A, B, E and F on,
To turn off the burners C and D, set 2 in the register M, (32), 0C ₁ , 0C ₃ = H (valve 15,13 open), 0C ₂ = L (valve
Set (14 Closed) (33). If the content of register M is 2 (burners A, B, E, F on, burners C, D off continued for 5 minutes), this time to turn burners A to D on, burners E, F off, Set register M to 3 (35) and set 0C ₁ and 0C ₂
= H (valves 15, 14 open), 0C ₃ = L (valve 13 closed) to set (36). If the content of the register M is 3 (burners A to D on, burners E, F off for 5 minutes), this time, in order to turn burners C to F on and burners A, F off, step 3
Go from 4 to 22 and set register M to 1 (22), 0
C _2, 0C ₃ = H (valves 14, 13 open), 0C ₁ = L (valve 15 closed) to set (23).

As described above, when one of the two pairs of combustion burners is switched to non-combustion and the other pair of non-combustion burners is switched to combustion, steps 24 to 28 are performed.
The inside / outside flow rate ratio setting is executed, and the process returns to step 3 through step 15. By repeating the above operations, while a _{Qc 1/6 <q 0 ≦} Qc 1/4, FIG. 9 are shown two pairs of burners in "1 row thinning pattern" combustion, a pair of burner In the non-combustion, the combustion / non-combustion of the burner pair is switched in a 5-minute cycle so that the non-combustion burner (1 pair) moves in the furnace length direction (the direction along the pass line).

<Accompanied to Qc ₁ in the range of q ₀ ≦ qc _1/4 is changed, the step _{24~28, Qc 1/4> Qc} 1/6 is within / outside flow ratio of the q ₂ burner 0 in / 100, the _{q 1 <Qc 1/4 ≦} q 2 in 50/50, also is set to q ₁ ≦ Qc _1/4 in 100/0.

Assigning a heat input Qc ₁ only two pairs of burners, when the amount of heat input Qc per one of the burner _1/4 is less than q _0, the process proceeds from step 18 to step 37 of the 11c diagrams the Qc ₁ Heat input Qc _1/2 per burner when assigned to one pair of burners
Is compared with q ₀ (37). That is, if the combustion burner is limited to one pair, it is determined whether the combustion can be operated at the minimum flame length _FL or more.

Qc _1/4 <q ₀ when ≦ Qc _1/2 is the amount of heat input Qc per one burner if that is, to assign Qc ₁ to a pair of burner _1/2
Is greater than or equal to q ₀ , a pair of burners can be burned with a set minimum flame length _FL or more. In this case, therefore, register N ₁ must be set to set data indicating that the pair of burners is set to combustion. Set 1 to (39) and set the 5 minute timer (4
0), 1 is set in the register M (41), and 0C ₁ and 0C ₂ = L
(Valves 15 and 14 closed), 0C ₃ = setting the H (valve 13 open) (4
2). The heat input Qc _1/2 per burner is the minimum heat input q per burner that can be operated at an internal / external flow rate ratio of 0/100.
Compared with ₂ (43), if Qc _1/2 exceeds q ₂ , the flow rate ratio is 0 /
Since it can be operated at 100, the data Pb indicating the opening ratio corresponding to the internal / external flow rate ratio 0/100 is output (set to the output port) to the drivers 26 to 31 (44). As a result, a pair of burners E, F
However, it ignites (combusts) at a flow rate ratio of 0/100.

The heat input Qc _1/2 per burner is q ₀ or more, but Qc ₁
/ 2 of the time ≦ q _2, comparing Qc _1/2 q ₁ and (45). Qc _1/2
> If it is q _1, heat input q = Qc per one burner _1/2, q
_Since the range is more than ₁ and less than q ₂ , the inner / outer flow rate ratio should be 50 /
To obtain 50, calculate the opening ratio Pb corresponding to 50/50,
The data indicating this is output (set to the output port) to the drivers 26 to 31 (46). As a result, a pair of burners E, F
However, it ignites (combusts) at a flow rate ratio of 50/50.

The heat input Qc _1/2 per burner is q ₀ or more, but Qc ₁
When / 2 ≤ q ₁ , the opening ratio Pb corresponding to 100/0 is calculated in order to set the internal / external flow rate ratio to 100/0, and the data indicating this is output to the drivers 26 to 31 (output port Set) (47). As a result, the pair of burners E and F have a flow ratio of 100/0.
Ignite (burn) with.

The flow advances to 15 from step 44 or 47, where waiting for the time-over of the T timer, also proceeds to step 3-6, if _{Qc 1/4 <q 0 ≦} Qc 1/2 is continued, For each time limit value T of the T timer, proceed to step 7-18-37-38, and then
At 38, since the register N ₁ is set to 1, the routine proceeds to step 48. In step 48, check if the 5-minute timer is over, and if not, step 4
4, 46 or 47 is executed, the process returns from step 15 to step 3, and this is repeated for T cycles. If the 5-minute timer has timed out in step 48, the 5-minute timer is reset (49) and the contents of the register M are referred to (50, 53). If the content of the register M is 1, this means that the burners E and F are currently set to on (combustion) and the burners A to D are set to off (extinguishing), and if it is 2, this is currently the burner. C and D are set to on (combustion) and burners A, B, E and F are set to off (fire extinguishing), and a value of 3 indicates that burner A, B
It shows that B is set to on (combustion) and burners C to F are set to off (extinguishing). Therefore, the contents of register M is 1
(Burner E, F on, burner A to D off for 5 minutes), this time set register M to 2 to turn burner C, D on and burner A, B, E, F off. Shi (51), 0
C _1, 0C ₃ = L (valves 15, 13 closed), 0C ₂ = H (valve 14 open) sets (52). The content of register M is 2 (burner C,
D on, burners A, B, E, F off continued for 5 minutes), and this time, to set burners A, B on and burners C to F off, set register M to 3 (54), 0C ₂ , 0C ₃ = L (valve 14, 1
3 closed), sets 0C ₁ = H (open valve 15) (55). The content of register M is 3 (burners A and B on, burners C to F)
After turning off for 5 minutes), in order to turn burners E and F on and burners A to D off, proceed from step 53 to 41 and set register M to 1 (41), 0C ₁ , 0C ₂ = L (valve
15 and 14 closed), 0C ₃ = H (valve 13 open) sets (42).

As described above, when one pair of combustion burners is switched to non-combustion and one pair of two non-combustion burners is switched to combustion, steps 43 to 47 are performed.
The inside / outside flow rate ratio setting is executed, and the process returns to step 3 through step 15. By repeating the above operations, while a _{Qc 1/4 <q 0 ≦} Qc 1/2, FIG. 9 to show a pair of burners with "two rows thinning pattern" combustion, the two pairs of burners The combustion / non-combustion of the burner pair is switched in a 5-minute cycle so that the combustion burner (1 pair) moves in the furnace length direction (the direction along the pass line) without combustion.

Qc _1/4 <along with the qc ₁ in the range of q ₀ ≦ Qc _1/2 is changed by the step 43 to 47, Qc _1/2> is among / outside flow ratio of the burner in the q ₂ 0 in / 100, the _{q 1 <Qc 1/2 ≦} q 2 in 50/50 and is set to q ₁ ≦ Qc _1/2 in 100/0.

Assigning a heat input Qc ₁ only one pair of burner, when the amount of heat input Qc _1/2 per one burner is less than q _0, the process proceeds from step 37 to step 17 of the first 11a Figure, 0C _1, 0C ₂ , 0C ₃
= L (valves 13 to 14 closed) is output and the opening of the flow rate control valve 9 is set to 0.
(OFF: Ps = 0) and set the internal / external flow rate ratio to 100/0 (17). That is, the supply of fuel to all burners is stopped.

The heating furnace shown in FIG.
The electric control system shown in the figure is equipped with one set for each of the three pairs of burner groups in each zone, a total of six sets, and each receives heat input data (Qc ₁ ) from the host computer,
As described above, the burner combustion control for each group is performed.

The determination and less processing steps in step 37 described above, when limiting the combustion burner in a pair, determine whether or not and the combustion burner can be operated combustion burner in the combustion control of the set minimum flame length F _L This is a one-to-one pair of moving combustion control processing steps, and the heat input amount Qc _{1 is set} to 1 by the determination in step 37.
Even if the burner is assigned only to a pair of burners, when the heat input Qc _{1/2 of each} burner is less than q ₀ , the burner is completely extinguished. However, in the actual operation of the heating furnace, when the combustion load factor per zone is 10% or more, the above control is performed to obtain the uniformity of the furnace temperature, but the combustion load factor per zone is less than 10%. In this case, if the burner is completely extinguished, the furnace temperature may drop extremely.Therefore, in order to avoid this, uniformity of the furnace temperature cannot be obtained, but even if the flame length of the burner becomes short, it burns. May be continued. In this case, in the judgment step of step 37, and the use of q _L of q _0> q _L ≧ 0 instead q ₀ of the criteria. In this way, the specified heat input Qc ₁
Even if becomes smaller, the burner is not completely extinguished and burner combustion continues. That is, the flame length of the combustion burner becomes shorter according to the amount of heat input, and the combustion burner continues the moving combustion control with the short flame length in a two-row thinning pattern. Where q _L
Is a criterion for determining whether or not to completely extinguish the combustion of the burner, and when q _L = 0, the extinction of the burner is not performed.

In the embodiment described above, the flow control valve 9 and the flow control valve 16
Although the drive system is driven by a motor, it may be an air pressure drive system using compressor air or a drive system using hydraulic pressure. Further, although the burner combustion / non-combustion switching unit is one pair (two), it may be performed individually.

The control operation of the above embodiment can be generalized and expressed as follows. That is, the total number of burners is N, and the heat input Qc assigned to the N burner groups is
Assuming that the minimum heat input amount for each flame length of one burner to be the minimum flame length _FL or more is q _0, and combustion / non-combustion is switched for each burner, (1) When Qc / N ≧ q ₀ , N = N burners are assigned to combustion. That is, all burners are continuously burned. Then, according to Qc / N, adjust the burner inner / outer flow rate ratio so that the flame length is within an appropriate range.

(2) When Qc / N <q ₀ ≤Qc / (N-1), n = (N
-1) Burning 1 burner and burning 1 = N−n burners, but at a predetermined time interval, one of the burners that had been burning was non-burning and non-burning Burner (1
Switch to combustion.

(3) In general terms, including (1) and (2) above, an integer n (where n ≦ N) burners of (n + 1) · q ₀ > Qc ≧ n · q ₀ are used for combustion. (N-n) burners were made non-combustion, but at a predetermined time interval, (N-n) of the burners that had been made non-combustion were made non-combustion (N-n) Switch the burner to combustion. The burner position for switching between combustion and non-combustion is sequentially moved in the burner arrangement direction.

〔The invention's effect〕

As described above, according to the combustion control method of the present invention, the heat input Qc allocated across the N burners, from heat input q ₀ Metropolitan which set minimum flame length F _L is obtained, the set minimum flame The number n of side burners that can be burned at a length of _FL or more is calculated, and only n burners are burned, so the flame length is always the set minimum flame length _FL or more, and the temperature distribution in the furnace in the flame length direction is uniform. It is highly likely. Moreover, when n <N, the flame (combustion burner) is moved at a predetermined time interval. Therefore, although the N−n burners are not burned due to the low load factor,
The uniformity of temperature distribution in the furnace in the arrangement direction of the side burners is high.

Therefore, even when the combustion load factor is low, the furnace temperature distribution can be made uniform, and the temperature distribution of the material to be heated can be made uniform.

[Brief description of drawings]

1 is a longitudinal sectional view of a continuous heating furnace for carrying out the present invention in one embodiment, FIG. 2 is a sectional view taken along line II-II of the continuous heating furnace shown in FIG. 1, and FIG. 3 is shown in FIG. It is the III-III sectional view taken on the line of the continuous heating furnace shown, and shows 1 zone which looked down from the top. FIG. 4 is an enlarged cross-sectional view of the side burner 5 shown in FIG.
FIG. 5 is a graph showing the relationship between the heat input amount q and the flame length of the side burner 5. FIG. 6 is a block diagram showing a control system configuration for implementing the present invention in one mode. FIG. 7 is a graph showing the relationship between the load factor per zone (horizontal axis) and the number of burners to burn (vertical axis) when the present invention is implemented, and FIG. 8 is the load factor per zone (horizontal axis). ) And the load factor of one burner to be burned (vertical axis). FIG. 9 is an explanatory diagram showing a control pattern of the control system shown in FIG. FIG. 10a is a graph showing the temperature distribution of the steel material in the heating furnace in the conventional combustion control, and FIG. 10b is a graph showing the temperature distribution of the steel material in the heating furnace in one embodiment of the present invention. 11a, 11b and 11c are flowcharts showing the control operation of the microprocessor 33 shown in FIG. FIG. 12 is a drawing showing the relationship between the shape of the flame in the heating furnace by conventional combustion control and the temperature distribution of the steel material in the heating furnace. FIG. 12 (a) shows the shape of the flame in the heating furnace. The cross-sectional view of the heating furnace shown in FIG. 12 (b) is a graph showing the temperature distribution of the steel material in the heating furnace. 1: pass line, 2: the material to be heated 3: furnace, 4: heating space 5: burner (side burner) 6 _1, 6 _2: Flame, 7: partition wall 8: side wall, 90: spout 9: flow rate adjustment valve, 10: reduction gear 11: motor, 12: an angle sensor 13 to 15: electromagnetic switching valve, 16 _{11-16 32:} flow ratio regulating valve 17: reduction gear, 18: combustion air inlet 19: an inner flow fueling Pipe, 20: Outflow fuel supply pipe 20M: Motor, 20S: Angle sensor 21: Burner tile, 32: Interface 33: Microprocessor

Front page continuation (72) Masato Masazawa Masato Masazawa 1 Kimitsu, Kimitsu-shi, Chiba Shin Nippon Steel Co., Ltd. Inside the Kimitsu Works, Ltd. (72) Hideo Kida 1-1-1 Edami, Hachiman-ku, Kitakyushu, Fukuoka (72) Inventor, Sadahiro Murata, 59, Nippon Steel Plant Design Co., Ltd., 46 Nakahara, Tobata-ku, Kitakyushu City, Fukuoka Prefecture (56) Reference JP-A-57-35615 (JP, A)

Claims (1)

[Claims] And 1. A heat input Qc instructed to continuous heating furnace, of each side burner the heating furnace, a minimum of heat input q ₀ Metropolitan to the heating furnace at the set minimum flame length F _L, (n + 1)・ Calculate the number n of side burners that can be assigned to combustion at the set minimum flame length _FL or more in the relationship of q ₀ > Q c ≧ n · q ₀ ; when n is equal to the total number N of side burners, burn all side burners. When n is smaller than the total number N of side burners, n side burners are assigned to combustion, N−n side burners are assigned to non-combustion, and n combustion side burner positions are determined in the side burner arrangement direction. Sequential transfer at time intervals; side burner combustion control method for continuous heating furnace.