JPH0774692B2 - Control method for heat storage type burner - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat storage type burner control method, and more particularly to control of combustion air and exhaust gas exhaust amount.

[0002]

2. Description of the Related Art Conventionally, as a heat storage type burner system, FIG.
Those shown in are known. In this regenerative burner system 101, a pair of burners 103 provided in the furnace 102
(103a, 103b) fuel nozzle 104 (104
a, 104b) are the fuel control valves 105 (105
a, 105b) having a branch pipe 106 (106a, 10)
6b) is connected to the fuel supply pipe 107, and the air nozzles 112 (112a, 112b) are respectively connected to the heat storage unit 11
Air supply / exhaust pipe 115 (1 having three (113a, 113b)
15a, 115b). Supply and exhaust pipe 1
The ends of 15 (115a, 115b) are connected to the four-way valve 120, and the combustion air supply pipe 1 extending from the four-way valve 120.
17 and the exhaust gas exhaust pipe 119 are respectively the air supply fan 116.
And the exhaust fan 118, and the combustion air supply pipe 117 and the exhaust gas exhaust pipe 119 are provided with limit orifices 131 and 132, respectively.

A regenerative burner system 1 having the above structure
01, the pair of burners 103 (103a, 103
b) is alternately switched to the combustion mode and the exhaust mode at every predetermined programmed time, and a constant amount of heat is alternately supplied into the furnace.

That is, as shown in the figure, the burner 103
When the exhaust gas in the furnace 102 is exhausted by the burner 103b (hereinafter, referred to as "second burner 103b") while the fuel and combustion air are burnt by a (hereinafter, referred to as "first burner 103a"), the fuel control valve 105b is Closed, fuel control valve 10
5a is opened, the supply of fuel to the second burner 103b is cut off, and the fuel in the gas state adjusted to a constant pressure by the fuel control valve 105 is supplied to the first burner 103a.
The valve body 121 of the four-way valve 120 is set in the illustrated solid line state, and the supply / exhaust pipe 115a communicating with the air nozzle 112a of the first burner 103a is communicated with the combustion air supply pipe 117.
The air supply / exhaust pipe 115b communicating with the air nozzle 112b of the second burner 103b is communicated with the exhaust gas exhaust pipe 119.

In this state, the fuel having a constant pressure adjusted by the fuel control valve 105a is supplied from the fuel supply pipe 107 to the fuel nozzle 104a of the first burner 103a. Combustion air is supplied to the air nozzle 112a through a combustion air supply pipe 117 and an air supply / exhaust pipe 115a, and the combustion air is preheated by heat stored in the heat storage medium 114a as described later. The pressure of the combustion air flowing through the air supply pipe 117 toward the four-way valve 120 is controlled by the limit orifice 131 to a constant pressure state. The fuel and the combustion air are supplied to the respective nozzles 104a, 1a.
It is injected into the furnace 102 from 12a and mixed and burned. On the other hand, the second burner 103b discharges the exhaust gas in the furnace 102 from the air nozzle 112b to the exhaust gas exhaust pipe 119 via the supply / exhaust pipe 115b based on the suction force of the exhaust fan 118, and passes through the heat storage unit 113b. The heat of is collected in the heat storage medium 114b housed in the heat storage unit 113b. Exhaust gas exhaust volume is limited to the limit orifice 1
It is controlled to a constant amount by adjusting the pressure at 32.

Next, when exhausting the exhaust gas in the furnace 102 by the first burner 103a while burning the fuel and combustion air by the second burner 103b, the fuel control valve 105a is closed, contrary to the above case. The fuel control valve 105b is opened, the fuel supply to the first burner 103a is cut off, and the fuel is supplied only to the second burner 103b. The valve body 121 of the four-way valve 120 is set to a dotted line state, the air supply / exhaust pipe 115b communicating with the air nozzle 112b of the second burner 103b is communicated with the combustion air supply pipe 117, and the air supply / exhaust communicating with the air nozzle 112a of the first burner 103a. The pipe 115a communicates with the exhaust gas exhaust pipe 119. Then, the fuel is supplied from the fuel supply pipe 107 to the fuel nozzle 104b of the second burner 103b, the air preheated by the regenerator 113b is supplied to the air nozzle 112b, and these are injected into the furnace 102 for mixed combustion. To be done. On the other hand, the first burner 103a
Based on the suction force of the exhaust fan 118, the air nozzle 11
The exhaust gas in the furnace 102 is discharged from 2b to the exhaust gas exhaust pipe 119 via the supply / exhaust pipe 115a, and the heat of the exhaust gas passing through the heat storage device 113a is recovered in the heat storage medium 114a housed in the heat storage device 113a. .

As described above, in the burner system 101, the fuel is alternately burned by the first burner 103a and the second burner 103b, and the burner 103 in the non-burning state is used.
The heat of the exhaust gas exhausted through the heat storage unit 113 is recovered by the heat storage unit 113, and the recovered heat is used for preheating the combustion air.
Therefore, there is an advantage that a large-scale collective heat exchanger-type heat exchanger is not required, and preheated air can be easily obtained by the heat accumulator 113 attached to the burner 103.

[0008]

However, in the above burner system, as shown in FIG.
Since the heat stored in the heat storage device is taken away by the combustion air, the preheating capacity of the heat storage device 113 gradually decreases. As a result, the temperature of the combustion air passing through the heat storage unit 113 gradually decreases, the passage resistance between the heat storage unit 113 and the air nozzle 112 decreases, and the supplied mass increases. However, the combustion air is supplied to the air supply pipe 11
The pressure is regulated to a constant pressure by a limit orifice 131 provided in No. 7. Therefore, the burner air ratio gradually rises during combustion, the oxygen concentration in the furnace tends to gradually increase, and the treatment conditions change. Regarding the exhaust gas, the heat storage medium 114 gradually becomes hot and the amount of heat recovery decreases, and the temperature of the exhaust gas passing through the heat storage unit 113 rises. But,
The exhaust fan 118 sucks the exhaust gas at a constant pressure. Therefore, if the passage resistance increases as the exhaust gas temperature rises, the exhaust mass tends to decrease and the in-reactor pressure tends to rise, and high-temperature exhaust gas blows out from the opening of the furnace 102 to cause energy loss and deterioration of the working environment. Be invited.

Therefore, in order to solve the above problems, it is possible to apply a feedback type flow rate control system 140 to the burner system 101 as shown in FIG. In this burner system 101, the fuel supply pipe 107, the combustion air supply pipe 117, and the exhaust gas exhaust pipe 1
19 are provided with flow rate control valves 141, 144, 147 and flow rate orifices 142, 145, 148, respectively, and the differential pressure signal transmitters 143, 146. 149 of the flow rate orifices 142, 145, 148 are respectively provided in the control system 1.
It is electrically connected to 40.

Then, the control system 140 calculates the fuel supply amount based on the signal output from the differential pressure signal transmitter 143 of the flow rate orifice 142, and the amount of combustion air supplied (theoretical value). Ask for. Further, the opening degree of the control valve 144 is adjusted based on the signal corresponding to the air supply amount (theoretical value), and the air supply amount (actual result) of the combustion air is calculated based on the differential pressure signal of the differential pressure signal transmitter 146. Value) is detected, and the opening degree of the control valve 144 is repeatedly corrected so that the theoretical value and the actual value match. The same applies to the exhaust gas exhaust amount, and the exhaust amount (actual value) is detected based on the differential pressure signal from the differential pressure signal transmitter 149 so that the exhaust amount (theoretical value) corresponding to the appropriate furnace pressure is adjusted. Then, the opening of the control valve 147 is repeatedly corrected so that the theoretical value and the actual value match.

However, as described above, the feedback type flow rate control system 140 repeats the operation of correcting the opening degrees of the control valves 144 and 147 based on the difference between the theoretical value and the actual value to obtain the actual value. It is a control loop that converges to a target value.

Therefore, there is a problem that it takes a considerable amount of time to reach convergence and cannot be applied to a burner system that switches combustion burners in a short time (for example, 20 seconds). Specifically, as shown in FIG. 7, it takes a considerable amount of time for the oxygen concentration in the furnace and the pressure in the furnace to stabilize, and the mode is reversed at the time of convergence.

Further, as shown in FIG. 8, when the heat storage unit 113 in the exhaust mode sucks the refractory powder and scale floating in the furnace together with the exhaust gas and becomes clogged or clogged, the internal pressure of the furnace changes from that point. Since it rapidly rises and a new control loop is started from there, more time is required until the furnace pressure stabilizes. Further, when the mode is reversed, the passage resistance of the combustion air increases and the supply amount decreases due to the blockage, so that the deviation of the oxygen concentration in the furnace becomes remarkable, and it takes a long time to correct it. Further, unless the closed regenerator 113 or the like is replaced, the deviation of the in-furnace oxygen concentration and the in-furnace pressure is repeated in the subsequent control loop, and a stable operating state cannot be obtained.

[0014]

SUMMARY OF THE INVENTION The present invention has been made to solve the problems in the above heat storage type burner system, and has a pair of two burners each having a fuel supply pipe and a heat storage pipe. Combustion in which the supply and exhaust pipes are connected to the combustion air supply pipe and the exhaust gas exhaust pipe through the switching valve, and the fuel and the combustion air are injected from one burner while the exhaust gas in the furnace is exhausted from the other burner. By alternately performing the states, the heat accumulated in the regenerator at the time of exhaust gas exhaust is used for preheating the combustion air, and the combustion air supply pipe and exhaust gas exhaust pipe are each provided with a control valve with an opening detector. Regarding the regenerative burner in which the control valve controls the combustion air supply amount and exhaust gas exhaust amount of the fan, the combustion air and the exhaust gas are exhausted based on the control calculation consisting of the following steps 1 to 7. And adjusts the flow rate. Step 1 Determine the opening of the control valve based on the theoretical flow rate, the flow rate coefficient obtained in the previous control calculation, the pressure on the fan side of the control valve, the furnace pressure, and the temperature of the fluid passing through the control valve. Step 2 Adjust the control valve to the opening obtained in Step 1 above. Step 3 After adjusting the control valve to the opening obtained in step 1, the burner side pressure and the fan side pressure of the control valve, the temperature of the fluid passing through the control valve, and the adjusted opening degree are used. Calculate the actual flow rate. Step 4 Obtain the flow rate difference between the theoretical flow rate and the actual flow rate. Step 5 If the flow rate difference is within a predetermined tolerance range, a flow rate coefficient is calculated based on the actual flow rate, the pressure on the burner side of the control valve, and the furnace pressure. If it is out of the range, the flow coefficient is calculated based on the theoretical flow rate, the pressure on the burner side of the control valve, and the furnace pressure. Step 6 The flow coefficient obtained in Step 5 is stored. Step 7 Return to Step 1 above.

[0015]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a burner system for carrying out a method of controlling a regenerative burner according to the present invention. In this burner system 1, a pair of burners 3 (3
a, 3b), the fuel nozzle 4 (4a, 4b) is provided with a fuel control valve 5 (5a, 5b), respectively, and a branch pipe 6 (6a, 6).
It is connected to the fuel supply pipe 7 via b). The fuel supply pipe 7 is provided with a flow rate orifice 9 with a differential pressure signal transmitter 8. The output of the differential pressure signal transmitter 8 is the control device 1.
It is output to 0. Further, the furnace 2 is provided with a pressure sensor 11 that detects the pressure PF in the furnace, and the output thereof is output to the control device 10.

The air nozzles 12 (12a, 12b) of the burners 3 (3a, 3b) are respectively regenerators 13 (13).
supply and exhaust pipe 15 (15a, 15b) having a, 13b)
Is connected to the heat storage device 13 (13a, 13b)
The heat storage medium 14 (14a,
14b) is filled. In addition, the supply / exhaust pipe 15
The ends of (15a, 15b) are connected to a four-way valve 20 to which the ends of an air supply pipe 17 connected to the air supply fan 16 and an exhaust gas exhaust pipe 19 connected to the exhaust fan 18 are connected.

This four-way valve 20 is equipped with a valve body 21,
The supply / exhaust pipe 1 connected to the burner 3a (hereinafter referred to as "first burner 3a") when the valve body 21 is in the solid line state.
5a communicates with the air supply pipe 17, and the other burner 3b
When the supply / exhaust pipe 15b connected to (hereinafter referred to as the "second burner 3b") communicates with the exhaust gas exhaust pipe 19 and the valve body 21 switches to the dotted line state based on the drive of the motor, conversely the first The supply / exhaust pipe 15a of the burner 3a is the exhaust gas exhaust pipe 19
The air supply / exhaust pipe 15b of the second burner 3b communicates with the air supply pipe 17.

The air supply pipe 17 is provided with a control valve 22 with an opening sensor 24 whose opening is adjusted by a motor 23, and the output of the opening sensor 24 is output to the control device 10 and the control device 10 outputs the output. The opening degree of the control valve 22 can be adjusted by driving the motor 23 on the basis of the drive signal. Further, the air supply pipe 17 is provided with a pressure sensor 25 and a temperature sensor 26 on the upstream side (fan side) and a pressure sensor 27 on the downstream side (burner side) in the combustion air supply direction (arrow X direction). The pressure data P1 and P2 and the temperature data T1 detected by them are output to the control device 10.

Similarly, the exhaust gas exhaust pipe 19 has a motor 2
Control valve 2 with opening sensor 30 whose opening is adjusted by 9
8 is provided, the output of the opening sensor 30 is output to the control device 10, and the opening of the control valve 28 can be adjusted by driving the motor 29 based on the drive signal from the control device 10. ing. Also, the exhaust gas exhaust pipe 19
Is provided with a pressure sensor 31 and a temperature sensor 32 on the upstream side (burner side) and a pressure sensor 33 on the downstream side (fan side) with respect to the exhaust gas discharge direction (arrow Y direction). P3, P4 and temperature data T2 are output to the control device.

In the burner system 1 having the above structure,
The first burner 3a and the second burner 3b alternately repeat the combustion mode and the exhaust mode. That is, within the programmed predetermined time, the fuel control valve 5a to the first burner 3a is opened, the fuel control valve 5b to the second burner 3b is closed, and the first burner 3a is passed through the fuel supply pipe 7 and the branch pipe 6a. Gasified fuel is supplied to the fuel nozzle 4a of the second burner 3b.
Shut off the fuel supply to. In addition, the valve body 21 of the four-way valve 20
Is set to the solid line state shown in the drawing, the supply / exhaust pipe 15a communicating with the air nozzle 12a of the first burner 3a is communicated with the air supply pipe 17, and the supply / exhaust pipe 15b communicating with the air nozzle 14b of the second burner 3b is connected to the exhaust gas exhaust pipe. Combustion air supplied to the air supply fan 16 is supplied to the air nozzle 12a of the first burner 3a, and the exhaust gas in the furnace 2 is discharged to the exhaust gas exhaust pipe 19 from the air nozzle 12b of the second burner 3b. . As a result, the fuel and the combustion air are injected from the first burner 3a into the furnace 2, and they are mixed and burned. In addition, the exhaust gas in the furnace 2 sucked by the second burner 3b is stored in the heat storage unit 1
When passing through 3b, heat is taken by the heat storage medium 14b. The combustion air supplied to the first burner 3a is stored in the heat accumulator 1
When passing through 3a, the heat accumulator 13 was used in the previous exhaust mode.
It is preheated by the heat stored in a and the preheated combustion air is injected into the furnace 2.

When the above operation mode is completed, the fuel control valve 5b for the second burner 3b is opened and the first burner is opened for the first predetermined time.
The fuel control valve 5a for the burner 3a is closed, and the fuel nozzle 4 of the second burner 3b is passed through the fuel supply pipe 7 and the branch pipe 6b.
The gasified fuel is supplied to b and the fuel supply to the first burner 3a is cut off. Further, the valve body 21 of the four-way valve 20 is set to the state shown by the dotted line in the figure, and the air nozzle 1 of the second burner 3b is set.
2b is connected to the air supply / exhaust pipe 15b, and the air supply / exhaust pipe 15a is connected to the air nozzle 12a of the first burner 3a.
The combustion air supplied by the above is preheated by the heat stored in the heat storage unit 13b in the above operation mode and supplied to the air nozzle 12b of the second burner 3b, and the exhaust gas in the furnace 2 is supplied from the air nozzle 12a of the first burner 3a. The exhaust gas is discharged to the exhaust pipe 19. As a result, the fuel and the combustion air are injected from the second burner 3b into the furnace 2, and they are mixed and burned. Further, the exhaust gas in the furnace 2 sucked by the first burner 3a is stored in the heat accumulator 1
When passing through 3a, heat is taken by the heat storage medium 14a. In actual operation, even if there are a plurality of pairs of burners, it does not depart from the gist of the present invention.

The control of the flow rate of the combustion air will be described. First, the basic formula used for the calculation of the flow rate control will be described.
The flow rate Qa of the combustion air that passes through the combustion air control valve 22 is expressed by Equation 1.

[Equation 1] Va: flow rate coefficient of control valve 22 P1: fan side pressure detected by pressure sensor 25 P2: burner side pressure detected by pressure sensor 27 Γa: air density

The above Γa is given by the equation 2.

[Equation 2] T1: Temperature detected by temperature sensor 26 1.293 in the formula is an air density in a standard state (temperature: 0 ° C., pressure: 760 mmHg).

Therefore, the above equation 1 can be changed to equation 3.

[Equation 3]

Next, since the air having the flow rate Qa determined by the above-mentioned equation 3 is sent into the furnace 2, the path from the outlet of the control valve 22 to the four-way valve 20, the heat accumulator 13, the air nozzle 12, and the inside of the furnace 2. For, the following equation 4 holds.

[Equation 4] Na: from the outlet of the control valve 22 to the four-way valve 20, the heat storage device 13,
Flow coefficient to the air nozzle 12 and the furnace 2 PF: Pressure in the furnace

Therefore, the relationship of the expression 5 is established from the expressions 3 and 4.

[Equation 5]

Here, Va (flow coefficient of the control valve 22)
Is experimentally obtained in advance. That is, air is flown through the control valve 22, and the temperature T, the flow rate Q, the opening Ra, and the pressure difference (P-P ') at that time are measured by appropriate means, and Va is calculated based on Equation 6.

[Equation 6] Further, the relationship between the opening degree Ra and the flow rate coefficient Va (see FIG. 2) is input to the control device 10 in advance.

Next, the air flow rate control will be specifically described. Now, it is assumed that one of the burners 3 is injecting fuel and combustion air to burn them. The theoretical value Qa of the combustion air flow rate at this time is calculated by calculating the fuel flow rate from the differential pressure signal output from the differential pressure signal transmitter 8 of the flow rate measuring means, that is, the flow rate orifice 9, and calculating the theoretical air flow rate corresponding to this fuel flow rate. It is calculated by multiplying the quantity by the air ratio.

Any time (time point of nth calculation)
The control calculation in ₍₁₎ is executed based on the equation _(7), and the flow coefficient Va _(n) of the control valve 22 at this time is obtained.

[Equation 7] Na _(n-1) : Flow coefficient from the outlet of the control valve 22 to the four-way valve 20, the heat accumulator 13, the air nozzle 12, the inside of the furnace 2 at the (n-1) th control calculation time Va _(n) : nth time Flow rate coefficient P1 _(n) of the control valve 22 at the time of the control calculation of the control valve 22 on the fan side of the control valve 22 at the time of the nth control calculation PF _(n) : The pressure T1 _{( n)} : Temperature of combustion air passing through the control valve at the Nth time

Here, Qa is a known numerical value obtained from the fuel supply amount as described above and input. Na _(n-1) is obtained from the following equation 8 in the previous control calculation.
P1 _{( n)} , PF _(n) and T1 _(n) are sensors 25 and 1, respectively.
It is obtained from the outputs of 1 and 26.

[Equation 8] Qa _(n-1) : Combustion air flow rate actual value at the (n-1) th control calculation time point P2 _(n-1) : Pressure on the fan side of the control valve 22 at the (n-1) th control calculation time point PF _(n-1) : Reactor pressure at the time of (n-1) th control calculation

As described above, the flow coefficient Va of the control valve
_{When (n)} is obtained, the opening degree Ra _(n) of the control valve 22 is obtained according to the relationship of FIG. 2 obtained in advance by the experiment, and the motor 23 is driven to set the opening degree of the control valve to this value Ra _(n). adjust.

Next, when the control valve opening adjustment is completed, the combustion air flow rate actual value Qa _(n) is obtained from equation ₍ 9 ₎ .

[Equation 9]

Next, the actual combustion air amount Qa _(n) is compared with the theoretical combustion air amount Qa, and the difference ΔQ (=
Check whether | Qa _(n) -Qa |) is within the allowable error δa. Then, when it is determined that the difference ΔQ is within the range of the allowable error δa, the arithmetic operation of the equation 10 is executed and Na
_(n) is obtained, and this is newly registered in the control device. on the other hand,
The process when it is determined to be out of the range (ΔQ> δa) will be described later. If it is determined that the value is out of the range, an alarm may be issued.

[Equation 10]

A storage device (not shown) is secured for each burner 3, and the final data before the burner 3 is switched from the combustion mode to the exhaust mode is stored in the storage device as Na _{(n + j).} , The first at the start of the next combustion
It is called at the time of the second control calculation. Similarly, burner 3
The final data P1 _{(n + j)} , PF _{(n + j)} , and T1 _{(n + j)} before switching from the combustion mode to the exhaust mode are also stored in the storage device, respectively, and these data are stored at the start of the next combustion. It is called during the first control calculation of. Then, these values Na _{(n) and the} like are used in the calculation of Expression 11 for obtaining _{(n + 1) th} Va _{(n + 1)} .

[Equation 11]

The self-recovery when the burner 3, the heat accumulator 13 and the like are clogged with scattered pieces of refractory material will be described. For example, as shown in FIG. 3, during exhaust of the first burner 3a,
When new clogging or blockage occurs in the burner 3a, the heat accumulator 13a, or the four-way valve 20, when the burner 3a is switched to the combustion mode, the final data stored in the storage device is called and the formula 12 is calculated. Va ₍₁₎ is obtained from the above, and the opening R ₍₁₎ of the control valve 22 is obtained based on this.

[Equation 12]

Next, when the combustion in the state of the opening R ₍₁₎ is completed, Qa ₍₁₎ is obtained from the equation 13 based on the data of various sensors in this combustion state.

[Equation 13]

Subsequently, the theoretical value Qa of the combustion air flow rate and the actual value Qa ₍₁₎ are compared. At this time, since the burner 3a or the like is clogged or blocked, ΔQ (= | Qa ₍₁₎ -Qa
|) Is outside the range of the allowable error δ. This is
Flow coefficient Na _{(n + j} ) and pressure data P1 used in the calculation of
_{(n + j)} , PF _{(n + j)} , and T1 _{(n + j)} are measurement data before clogging, and can be easily understood because they do not reflect the state after clogging. Therefore, the air ratio of the combustion air to the fuel becomes lower than the set value, and the oxygen concentration in the furnace decreases as shown in FIG.

Therefore, in the case of ΔQ> δ, based on the combustion air flow rate theoretical value Qa and the pressure data P2 ₍₁₎ and PF ₍₁₎ , Equation 1
The flow rate coefficient Na ₍₁₎ is newly obtained from 4, and this is stored in the storage device and used for the calculation of the equation 15 in the second control calculation.

[Equation 14]

Further, the second control calculation is executed based on the equation (15 ₎ to determine a new Va ₍₂₎ and the corresponding opening Ra ₍₂₎ of the control valve 22.

[Equation 15]

As a result, as shown in FIG. 3, the oxygen concentration in the furnace returns to the proper value when the second flow rate control is completed. Therefore, the air ratio deviates from the set value due to the abnormality of the air path generated during the exhaust mode from the time when the mode is switched to the time when the second control operation is completed. Further, as described above, since each control operation is a simple operation that does not require convergence, the processing time of the computer is short, and the deviation amount and the deviation time of the oxygen concentration in the furnace are extremely small.

The flow rate control of exhaust gas will be described. First, the basic formula used for the calculation of the flow rate control will be described.
The flow rate Qw of the exhaust gas that passes through the control valve is represented by Expression 16.

[Equation 16] Vw: Flow coefficient of control valve P3: Pressure of combustion air detected by pressure sensor 32 on the upstream side of the control valve P4: Pressure of combustion air detected by pressure sensor 33 on the downstream side of the control valve Γw: Exhaust gas density

The above Γw is given by equation (17).

[Equation 17] T2: Exhaust gas temperature detected by the temperature sensor 1.4 in the formula is a standard state (temperature: 0 ° C, pressure: 7
It is the exhaust gas density at 60 mmHg).

Therefore, the above equation 16 can be changed to equation 18.

[Equation 18]

Next, since the exhaust gas having the flow rate Qw determined by the above equation 18 is sent to the control valve 28, the path to the inside of the furnace 2, the air nozzle 12, the heat accumulator 13, the four-way valve 20, and the inlet of the control valve 28. For, the following equation 19 holds.

[Formula 19] Nw: Inside the furnace 2, air nozzle 12, regenerator 13, four-way valve 2
0, flow coefficient to the inlet of control valve 28

Therefore, from the above Equations 18 and 19, Equation 2 is obtained.
0 holds.

[Equation 20]

The Vw (flow coefficient of the control valve) is experimentally obtained in advance. That is, the exhaust gas is caused to flow through the control valve 28, the temperature T, the flow rate Q, the opening degree Rw, and the differential pressure (PP ′) at that time are measured by appropriate means, and Vw is obtained based on the equation 21.

[Equation 21] Further, the relationship between the opening degree Rw and the flow coefficient Vw (see FIG. 2) is input to the control device 10 in advance.

Next, the exhaust gas flow rate control will be specifically described. Now, it is assumed that one of the burners 3 injects fuel and combustion air, and the other burner 3 sucks in and exhausts the exhaust gas in the furnace. Exhaust gas flow rate theoretical value Qw at this time
Is calculated by calculating the fuel flow rate from the differential pressure signal output from the differential pressure signal transmitter 8 of the flow rate orifice 9, that is, the fuel flow rate measuring means, and multiplying the theoretical exhaust gas amount corresponding to this fuel flow rate by an appropriate ratio. To be

Any time (n-th calculation time point)
The control calculation in (1) is executed based on the equation 22, and the flow coefficient Vw (n) of the control valve at this point is obtained.

[Equation 22] Nw _(n-1) : Flow coefficient to the inlet of the furnace 2, the air nozzle 12, the heat accumulator 13, the four-way valve 20, the control valve 28 at the time of the (n-1) th control calculation Vw _(n) : nth time Flow rate coefficient PF _(n) of the control valve 28 at the time of the control calculation of the control valve 28 at the n-th control calculation time P4 _(n) : Pressure of the fan side of the control valve 28 at the time of the n-th control calculation T2 _{(n )} : Temperature of exhaust gas passing through the control valve 28 at the n-th control calculation time point

Here, Qw is obtained from the fuel supply amount,
It is a known number entered. Nw _(n-1) is obtained from the following equation 23 in the previous control calculation. PF
_(n) , P4 _(n) and T2 _(n) are respectively obtained from the output from the sensor.

[Equation 23] Qw _(n-1) : Exhaust gas flow rate actual value at the (n-1) th control calculation time point P3 _(n-1) : Burner side pressure PF of the control valve 28 at the (n-1) th control calculation time point _(n-1) : Pressure inside the furnace 2 at the time of the (n-1) th control calculation

As described above, the flow coefficient Vw of the control valve
_{When (n)} is obtained, the opening Rw _(n) of the control valve is obtained in accordance with the relationship of FIG. 2 obtained in advance by experiment, and the motor is driven to adjust the opening of the control valve 28 to this value Rw _(n). To do.

Next, when the control valve opening adjustment is completed, the exhaust gas flow rate actual value Qw _(n) is obtained from equation ₍ 24 ₎ .

[Equation 24]

Then, the actual value Qw _(n) of the exhaust gas flow rate is compared with the theoretical value Qw of the exhaust gas flow rate, and the difference ΔQ (=
Confirm whether | Qw _(n) -Qw |) is within the allowable error δw. Then, when it is determined that the difference ΔQ is within the range of the allowable error δw, the calculation of Expression 25 is executed and Nw
_(n) is obtained, and this is newly registered in the control device. on the other hand,
The process when it is determined to be out of the range (ΔQ> δw) will be described later. If it is determined that the value is out of the range, an alarm may be issued.

[Equation 25]

The storage device is secured for each burner, and the final data before the burner is switched from the exhaust mode to the combustion mode is stored in the storage device as Nw _{(n + j)} , and when the next exhaust starts. It is called during the first control calculation. Similarly, the final data P4 _{(n + j)} , PF before the burner is switched from the exhaust mode to the combustion mode
_{(n + j)} and T2 _{(n + j)} are also stored in the storage device, respectively.
These data are called at the time of the first control calculation at the start of the next exhaust. Then, these values Nw _{(n) and the} like are used in the calculation of Expression 26 for obtaining Vw _{(n + 1)} at the (n + 1) th time.

[Equation 26]

Next, a description will be given of self-recovery when a scattered piece of refractory material is clogged in the burner, the heat accumulator, or the like. For example, during exhaust of the burner 3, the burner 3 and the regenerator 1
2. If a new clogging or blockage occurs in the four-way valve 20,
The difference ΔQ (= the theoretical value Qw of exhaust gas and the actual value Qw _(n)
| Qw _(n) -Qw |) is outside the range of the allowable error δw.
As a result, the pressure inside the furnace 2 rises as shown in FIG.

Therefore, when ΔQ> δw, the exhaust gas flow rate theoretical value Qw and the pressure data PF _(n) and P3 measured this time are measured.
Based on _(n) , a new flow coefficient Nw _(n) is calculated from Equation 27,
The value is stored in the storage device and used for the operation of the equation 26 in the (n + 1) th control operation.

[Equation 27]

Thus, as shown in the figure, (n + 1)
When the flow rate control for the second time is completed, the pressure in the furnace returns to an appropriate value, and returns to an appropriate exhaust gas exhaust state within a short time.

[0057]

As is apparent from the above description, according to the heat storage burner control method of the present invention, even if the path from the burner to the combustion air control valve or the exhaust gas control valve is abnormal, Abnormality occurs in the furnace pressure or the oxygen concentration in the furnace for a short period of time, but this abnormal state is quickly resolved and returns to an appropriate operating state. Therefore, even if the temperature and ventilation of the burner, the heat storage device, and the switching valve change from moment to moment,
The air ratio and the pressure inside the furnace can always be corrected to appropriate values. In other words, there is no overshoot or undershoot during control, the proper flow rate can be reproduced immediately after the combustion / exhaust mode starts, and there is a situation where the heat storage device is clogged with fragments of refractory and pressure loss increases or decreases. If it occurs, it can be immediately detected and corrected to an appropriate flow rate in real time. Therefore, even in a combustion system that controls the burner to switch between the combustion state and the exhaust state in a short time of about 20 seconds,
The air ratio and furnace pressure can always be maintained properly.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a heat storage type burner system.

FIG. 2 is a diagram showing a relationship between an opening degree of a control valve and a flow coefficient.

FIG. 3 is a diagram showing a control result of the present invention.

FIG. 4 is a control circuit diagram of a conventional burner system.

5 is a diagram showing a control result of the burner system shown in FIG.

FIG. 6 is a control circuit diagram of another conventional burner system.

7 is a diagram showing a control result of the burner system shown in FIG.

FIG. 8 is a diagram showing a control result when the burner system shown in FIG. 6 is abnormal.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Burner system, 2 ... Furnace, 3 ... Burner, 4 ... Fuel nozzle, 5 ... Fuel control valve, 7 ... Fuel supply pipe, 8 ... Differential pressure signal transmitter, 9 ... Flow rate orifice, 10 ... Control device, 11 ...
Pressure sensor, 13 ... Heat storage device, 16 ... Air supply fan, 17 ...
Air supply pipe, 18 ... Exhaust fan, 19 ... Exhaust gas exhaust pipe,
20 ... Four-way valve, 22, 28 ... Control valve, 24, 30 ... Opening sensor, 25, 27, 32, 33 ... Pressure sensor, 26,
31 ... Temperature sensor.

Claims (1)

[Claims] 1. A fuel supply pipe and a supply / exhaust pipe having a heat accumulator are respectively connected to two burners forming a pair, and the supply / exhaust pipe is connected to a combustion air supply pipe and an exhaust gas exhaust pipe via a switching valve, By alternately performing a combustion state in which fuel and combustion air are injected from one burner and exhaust gas in the furnace is exhausted from the other burner, the heat accumulated in the heat accumulator at the time of exhaust gas exhaust is used to preheat combustion air. A regenerative burner in which a control valve with an opening detector is provided in each of the combustion air supply pipe and the exhaust gas exhaust pipe, and the combustion air supply amount and exhaust gas exhaust amount of the fan are adjusted by these control valves. A method for controlling a regenerative burner, characterized in that the flow rates of combustion air and exhaust gas are adjusted based on a control calculation including the following steps. Step 1 Determine the opening of the control valve based on the theoretical flow rate, the flow rate coefficient obtained in the previous control calculation, the pressure on the fan side of the control valve, the furnace pressure, and the temperature of the fluid passing through the control valve. Step 2 Adjust the control valve to the opening obtained in Step 1 above. Step 3 After adjusting the control valve to the opening obtained in step 1, the burner side pressure and the fan side pressure of the control valve, the temperature of the fluid passing through the control valve, and the adjusted opening degree are used. Calculate the actual flow rate. Step 4 Obtain the flow rate difference between the theoretical flow rate and the actual flow rate. Step 5 If the flow rate difference is within a predetermined tolerance range, a flow rate coefficient is calculated based on the actual flow rate, the pressure on the burner side of the control valve, and the furnace pressure. If it is out of the range, the flow coefficient is calculated based on the theoretical flow rate, the pressure on the burner side of the control valve, and the furnace pressure. Step 6 The flow coefficient obtained in Step 5 is stored. Step 7 Return to Step 1 above.