JP3024520B2 - Combustor control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a combustor for premixing and burning a vaporized liquid fuel and combustion air.

[0002]

2. Description of the Related Art FIG.
FIG. 1 is a cross-sectional view of a combustor of a conventional liquid fuel combustion device disclosed in Japanese Unexamined Patent Publication. In the figure, 1 is a vaporizer forming a vaporization chamber for vaporizing liquid fuel, and 2 is an electric heater buried in the side wall of the vaporizer 1 and heating the vaporizer 1. Reference numeral 3 denotes a throttle unit fitted and fixed to the upper part of the vaporizer 1, 4 denotes a burner head provided on the upper part of the throttle unit 3, and 5 denotes a plurality of flame holes provided on a side wall of the burner head 4. Reference numeral 6 denotes a wire mesh wound tightly around the outer peripheral surface of the burner head 4, 7 denotes a cap disposed on the wire mesh, 8
Is a special screw whose one end is embedded in the throttle unit 3 to fix the burner head 4 and the cap 7 to the throttle unit 3.

Reference numeral 9 denotes a mixing plate provided in the burner head 4 and having a plurality of holes on the bottom surface. The mixing plate 9 straightens the vaporized liquid fuel and then jets the fuel from the plurality of flame holes 5. . Reference numeral 10 denotes an annular flame holding ring attached to the upper portion of the vaporizer 1 so as to surround the burner head 4.

[0004] Reference numeral 11 denotes a nozzle installed on the side wall of the carburetor 1 and opening into the carburetor 1. This nozzle 11 is an air supply pipe (not shown) communicating with a combustion blower (not shown). It is connected to the. Further, the nozzle 11 includes an inlet portion 11a, a tapered portion 11b, and a throat portion 11c. Numeral 12 denotes a fuel supply pipe arranged coaxially with the nozzle 11 so that a combustion supply port 12a at the tip protrudes from the throat 11c. Liquid fuel in a fuel tank (not shown) is supplied to the fuel supply pipe. The fuel gas is supplied to the carburetor 1 by a fuel pump (not shown) via the fuel pump 12.

Next, the operation will be described. Electric heater 2
, The vaporizer 1 is preheated to a temperature (200 to 300 ° C.) required for vaporizing the liquid fuel. After the completion of the preheating, the combustion air sent from the combustion blower to the air supply pipe is supplied from the nozzle 11 to the carburetor 1. From the fuel supply pipe 12, liquid fuel is supplied to the carburetor 1 in such an amount that the primary air ratio (= supply air amount / theoretical air amount) becomes about 0.8.

[0006] The supplied liquid fuel is atomized by the flow of combustion air, and is vaporized on a preheated vaporizing surface. When the vaporized liquid fuel passes through the throttle unit 3, it is further premixed with the combustion air to have a uniform concentration distribution. Thereafter, the premixed air of the liquid fuel and the combustion air is rectified by passing through a plurality of holes in the bottom surface of the mixing plate 9, and the flow velocity distribution in the vertical direction of the burner head 4 is controlled by the effect of the side wall of the mixing plate 9. Becomes uniform. The premixed gas is ignited by a igniter (not shown) on the flame hole 5 of the burner head 4 to form a primary flame 13 and a secondary flame 14. After the start of combustion, heat is recovered from the flame by the flame holding ring 10 or the like, so that the vaporizer 1 is heated, so that input to the electric heater 2 is unnecessary.

By the way, when extinguishing such a combustion device, the application of voltage to the fuel pump and the combustion blower is simultaneously released. In this case, the fuel pump stops almost instantaneously, whereas the combustion blower stops rotating after a few seconds, even if the application of voltage is stopped, by gradually reducing the rotation speed due to its inertia. Thus, reduction of fuel early as shown by the solid line in FIG. 11, stopping the power supply to the T ₀ at the fuel pump, the evaporation quantity becomes zero at T _1.

On the other hand, the amount of combustion air decreases more slowly than fuel, and the supply stops at T ₂ as shown by the broken line. In this type of combustor, combustion is continued from T ₀ to T at the time of fire extinguishing because the ratio of combustion air to fuel (primary air ratio) is in the combustible range, but after T, the air becomes excessive. As a result, the flame blows off. As described above, due to the imbalance between the two decreasing speeds, the primary air ratio at the time of fire extinguishing increases instantaneously, and the flame blows out, so that the unburned fuel in the hatched portion in FIG. 11 is discharged into the room. At this time, a part of the unburned fuel comes into contact with the high-temperature part of the combustion device and is partially oxidized to generate a substance such as aldehyde, thereby giving an unpleasant odor with irritation.

As a measure for reducing the fire extinguishing odor, a control device for a combustor which emits less odor during fire extinguishing without complicating the structure of the combustor has been considered. For example, JP-A-6
The combustion operation shown in JP-A-94235 is basically the same as that of the combustion device shown in FIG. 10, and the combustion air from the combustion blower (not shown) and the fuel supply means (not shown) are used. Is vaporized and mixed in the vaporization chamber 1 and burned in the burner head 4. When a user turns off a power switch (not shown) to extinguish a fire during a fire extinguishing operation, the application of a voltage to a fuel pump (not shown) is stopped. In this case, the method of stopping the fuel pump is the same as that in FIG.
As shown by the solid line in FIG. 12, the decrease in the fuel becomes zero at the time from T ₀ to T ₁ , which is the same decrease rate as in FIG.

On the other hand, with respect to the combustion air, the drive circuit of the combustion blower (not shown) is switched to perform the half-wave rectification or full-wave rectification shown in FIG. (Not shown) brake to reduce air flow. At this time, the flow rate of the combustion air is shown in FIG.
As shown in FIG. 11, it becomes zero in a short time as compared with FIG.
Therefore, since the combustion air becomes substantially equal to the fuel decreasing speed, the combustion amount decreases while the ratio of the combustion air to the fuel (primary air ratio) is kept constant. Then, as the amount of combustion decreases, the primary flame 13 approaches the burner head, so that the primary flame 13 is cooled by the burner head 4, and when the amount of cooling exceeds the amount of combustion (time T in FIG. 12), the flame is generated. To extinguish the flame. The unburned fuel in this case is the portion shown by the diagonal lines in FIG. 12 and is smaller than that in FIG.

[0011]

Since the conventional control device for a combustor is constructed as described above, it is substantially constant when the AC power supply voltage is half-wave rectified to extinguish the fire and the brake is applied to the combustion blower. , And the rate of decrease of the combustion air is fixed. However, in actual combustion control, the rate of decrease in fuel varies greatly depending on the amount of combustion and the structure of the combustor, such as the delay in vaporization during fire extinguishing and the delay in the time from the vaporization chamber to the flame hole. is not. As a result, there is a problem that it is difficult to extinguish the fire by reducing the amount of combustion while keeping the ratio (primary air ratio) constant, under the condition that the reduction speeds of the combustion air and the fuel are almost the same.

Further, when the combustion blower is rotating at a low speed, the time required for the air flow rate to become zero is short because the inertia force is small. Further, the low-speed rotation range is often used for weak combustion, and the vaporization delay tends to be noticeable during weak combustion. For example, the rate of reduction of combustion air becomes faster than that of fuel. as shown, although the advantage the same as that of delaying the decrease start time T ₀₁ of the combustion air, as well as the ratio of the supply amount decreases at the start of the combustion air and fuel is lost (the fuel concentration becomes thinner), There is a problem that the deodorizing effect is weakened.

[0013] Conversely, if the combustion air is reduced more slowly than the fuel, the decrease start time T of the fuel as shown in FIG. 15
₀₂ , the same effect is obtained by keeping the fuel concentration of the air-fuel mixture in the flammable range during the fire extinguishing operation (T _{0 to} T ₂ ), but the ratio of combustion air to fuel at the start of the decrease in the supply amount collapses. (fuel concentration <br/> degree of darkening), not only deodorant effect fades, tends to be red fire extinguishing, there is a problem that causes that inspire distrust to the user.

Further, when the AC power supply voltage is half-wave rectified and a brake is applied to the combustion blower at the time of fire extinguishing, a sudden braking force is applied, which causes a problem that noise (abnormal stop sound) is generated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a control device for a combustor having a wide combustion range and various vaporization characteristics, which emits little odor when extinguishing a fire. The purpose is to obtain.

[0016]

SUMMARY OF THE INVENTION A control device for a combustor according to the present invention includes a vaporizer for vaporizing liquid fuel, a fuel supply means for supplying the liquid fuel to the vaporizer; A flame hole for burning premixed air, a combustion blower for supplying combustion air, a control circuit for controlling the combustion blower and the fuel supply means, and an AC power supply voltage of zero volts in the control circuit. A zero-cross pulse generating circuit that generates a pulse at the crossing point, a signal generating unit that outputs an oscillation output signal based on the pulse generated by the zero-cross pulse generating circuit, and between the combustion blower and the AC power supply voltage. A thyristor inserted and connected;
A firing circuit for firing the thyristor based on an oscillation output signal output from the signal generating means. In the control device for a combustor in which the concentration of the premixed gas during operation is maintained in a flammable range, a counter for counting a half cycle of the waveform of the AC power supply voltage is provided in the signal generating means, and the signal generating means is When the fire is extinguished, 1 / n of the n cycles counted by the counter during the fire extinguishing operation is applied to the combustion blower to apply a brake, thereby applying a brake.

Further, a control device for a combustor according to the present invention includes a vaporizer for vaporizing a liquid fuel, a fuel supply means for supplying the liquid fuel to the vaporizer, and a premix of the vaporized liquid fuel and combustion air. A flame hole for burning air, a combustion blower for supplying combustion air, a control circuit for controlling the combustion blower and the fuel supply means, and a point where an AC power supply voltage crosses zero volts in the control circuit. A zero-cross pulse generating circuit that generates a pulse, a signal generating unit that outputs an oscillation output signal based on the pulse generated by the zero-cross pulse generating circuit, and is inserted and connected between the combustion blower and the AC power supply voltage. A thyristor; and a firing circuit for firing the thyristor based on an oscillation output signal output from the signal generating means. In a control device of a combustor in which a blower is braked to reduce an air flow rate and keep a concentration of a premixed gas during a fire extinguishing operation within a flammable range, a half of a waveform of the AC power supply voltage is provided in the signal generating means. A counter for counting cycles is provided, and the signal generating means alternately applies a 1 / n voltage and a 1 / m voltage, which are output in only one cycle, to the combustion blower out of n or m cycles counted by the counter. And then apply the brakes.

Further, the control device for a combustor according to the present invention, in the above-described apparatus, decelerates the combustion blower by inertia for a certain period from the start of fire extinguishing, and thereafter sets the voltage to 1 / n or 1 / n voltage. The 1 / m voltage is applied alternately to stop.

Further, the control device for a combustor according to the present invention, in the above-mentioned device, wherein a 1 / n voltage or a 1 / n voltage and a 1 / m voltage are alternately applied to the combustion fan for a certain period from the start of fire extinguishing. This is configured to decelerate by applying the voltage and then stop by inertia.

Further, a control device for a combustor according to the present invention includes a fuel supply means for supplying a liquid fuel, a combustion blower for supplying combustion air, and a control for controlling the combustion blower and the fuel supply means. A circuit, a vaporizer for vaporizing the liquid fuel supplied by the fuel supply means, and a flame hole for burning a premixed air of the liquid fuel and the combustion air vaporized by the vaporizer. The control circuit stops the combustion blower while controlling the rotation speed of the combustion blower so as to maintain the concentration of the premixed gas in the flammable range.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a control device for a combustor according to the present invention. The same or corresponding parts as in the conventional example shown in FIG.

In FIG. 1, reference numeral 21 denotes a fuel pump (fuel supply means) for supplying a liquid fuel used in the conventional example. One end of the fuel pump is located in a fuel tank 22, and the other end is a fuel supply pipe. 12 is connected. Also, 2
3 is an air supply pipe (combustion air supply path) connected to the nozzle 11 and supplying combustion air, and 24 is a combustion blower. 25 is a control circuit for controlling the fuel pump 21 and the combustion blower 24. 26 is an AC power supply voltage, 27 is an insulation transformer, and the primary side is connected to the AC power supply voltage 26.

Reference numeral 28 denotes a zero-cross pulse generating circuit which is connected to the secondary side of the insulating transformer 27 and generates a pulse when the AC power supply voltage 26 crosses zero volts. Reference numeral 29 denotes a pulse generated by the zero-cross pulse generating circuit 28. Signal generating means for outputting an oscillation output signal based on the Reference numeral 31 denotes a firing circuit for firing a thyristor 32 inserted and connected between the combustion blower 24 and the AC power supply voltage 26 based on the oscillation output signal output from the signal generating means 29. 3
Reference numeral 3 denotes a pump drive circuit that drives the fuel pump 21 based on a drive signal from the microcomputer 30.

Next, the ignition operation will be described. The operation of starting combustion (ignition) is almost the same as in the conventional example. Vaporizer 1
Is heated to a predetermined temperature (200-300 ° C.)
The combustion blower 24 rotates, and the amount of air required for combustion is supplied to the carburetor 1. After operating the ignition device (not shown), the supply of liquid fuel is started by the fuel pump 21. The liquid fuel ejected into the vaporizer 1 is vaporized on the vaporizing surface and mixed with the combustion air to become a premixed gas. This premixed gas passes through the throttle portion 3 and the mixing plate 9 and is ignited on the flame hole 5 of the burner head 4 to form a primary flame 13 and a secondary flame 14. The burned gas is mixed with air from a convection fan (not shown) and used for room heating or the like.

FIG. 2 is a flowchart showing the operation of the first embodiment of the present invention having the above configuration. After the ignition operation, combustion is started (step 50). During the combustion, the microcomputer 30 determines the amount of combustion based on the difference between the set temperature and the room temperature, and sends a predetermined signal to the pump drive circuit 33 to supply the fuel corresponding to the amount of combustion to the carburetor 1. Output to drive the fuel pump 21.

On the other hand, in order to keep the concentration of the premixed gas constant, and to supply combustion air corresponding to the fuel to the carburetor 1, the combustion blower 24 is provided with a microcomputer 30.
(Step 51). Power switch (not shown)
Is turned off to perform a fire extinguishing operation, a fire extinguishing process is performed (step 52), and the microcomputer 30 stops applying voltage to the fuel pump 21 and stops supplying fuel (step 53).

On the other hand, for combustion air, a counter provided in the signal generating means 29 is incremented for each zero cross pulse (FIG. 3B) output from the zero cross pulse generating circuit 28 (step 54). If this count value is smaller than the predetermined value n (step 55), the signal generator 29 outputs a Lo signal (step 5).
6), no voltage is applied to the combustion fan 24. Steps 54 to 56 are repeated until the counter value reaches n. When the counter value reaches n, the counter is cleared to zero (step 57), and a Hi signal is output from the signal generation means 29 (step 58). A voltage is applied to 24.

By repeating the above processing, a voltage of 1 / n is applied to the combustion blower (d in FIG. 3). Thereafter, when the fire extinguishing process is completed, the Lo signal is output from the signal generating means 29 (step 59), and the combustion blower 24 is stopped. Here, if the value of the predetermined value n is set to 2, the waveform becomes the same as that in the case of the conventional half-wave rectification, and the decreasing speed of the combustion air becomes the fastest. Conversely, as the value of the predetermined value n increases, the decrease speed decreases.

Here, if n becomes too large, FIG.
Is the same as the decreasing speed when stopping by inertia as indicated by the broken line. If the predetermined value n is determined in accordance with the amount of combustion immediately before the fire extinguishing and the vaporization characteristics of the combustor, even in a combustor having a wide combustion range and various vaporization characteristics, the concentration of the air-fuel mixture during the fire extinguishing operation can be reduced. Since it is possible to extinguish the fire by keeping it constant from the start of the decrease in the supply amount, it is possible to reduce the amount of unburned fuel, and to obtain a control device for a combustor that emits less odor during fire extinguishing.

The drive signal of the fuel pump 21 is pulse-controlled as shown in FIG. 4E. However, when the brake control of the combustion fan 24 is started based on the user's operation switch OFF signal, the fuel is reduced. There is a difference in timing of a maximum of one pulse period between the start and the start of reduction of the combustion air. In particular, in the case of weak combustion, the interval of the cycle is long and the deviation is large. Therefore, the reference is not the OFF signal of the power switch,
After turning off, one pulse of the pump drive signal is output (e in FIG. 4).
By using this pulse as a reference, the timing at which the supply of fuel and combustion air starts to decrease can be accurately adjusted.

Embodiment 2 FIG. FIG. 5 is a flowchart showing the operation according to the second embodiment of the present invention. Note that FIG.
This applies to the output signal processing unit (60 in FIG. 2) shown therein. In the fire extinguishing process, a counter provided in the signal generating means 29 is incremented for each zero cross pulse (step 61). If the flag is 0 (step 62), the same operation as in the first embodiment is performed, and
/ N is applied.

When the counter becomes n and the signal output becomes Hi (step 67), the flag is inverted (0 → 0).
1) Do (step 66). Next, after the counter is incremented, the flag is 1, so that it is processed by the predetermined value m (step 68), a voltage of 1 / m is applied to the combustion fan 24 in the same manner as in the above processing, and the flag is inverted again. (1 →
0). Thereafter, this process is repeated, and an output signal as shown in FIG. 6C is oscillated, and a 1 / n voltage and a 1 / m voltage as shown in FIG. 6D are alternately applied to the combustion fan 24. become. As a result, it is possible to set more finely than the decreasing speed of the combustion blower 24 shown in the first embodiment, and to supply the mixture concentration at the time of the fire extinguishing operation in a combustor having a wider combustion range and various vaporization characteristics. Since it is possible to extinguish the fire by keeping it constant from the start of the amount decrease, it is possible to reduce the amount of unburned fuel and to obtain a control device for a combustor with less odor discharged at the time of fire extinguishing.

Embodiment 3 FIG. FIG. 7 is an explanatory diagram showing how fuel and combustion air are reduced when a combustor according to a third embodiment of the present invention is extinguished. During fire fighting, the combustion machine such as the rate of decrease in fuel changes as shown by the solid line in FIG. 7 by vaporization delay in, or in the case of combustion rate, T ₀₃ from the decrease start T ₀
The output to the inter-combustion blower 24 is stopped to reduce the supply amount of combustion air by inertia. The braked to the combustion blower 24 at the time of T ₀₃ reduces the air amount to zero at T ₂ in.

By operating as described above, even when the fuel decrease due to the vaporization delay after the fire extinguishing is not linear as in the conventional example, but parabolically decreases as shown by the solid line in FIG.
Since the concentration of the air-fuel mixture during the fire extinguishing operation can be reduced and extinguished while maintaining a constant concentration from the start of the decrease in the supply amount, it is possible to reduce the amount of unburned fuel and obtain a control device for a combustor that emits less odor during fire extinguishing. Can be.

Embodiment 4 FIG. FIG. 8 is an explanatory diagram showing how fuel and combustion air are reduced at the time of extinguishing a combustor according to a fourth embodiment of the present invention. Combustor, such as the rate of decrease in fuel changes as shown by the solid line in FIG. 8 by vaporization delay in the time of extinguishing, or if the combustion rate, during the period from the decrease start T ₀ to T _03, a brake to the combustion blower 24 To rapidly reduce the amount of air, and then, at _T03 , the combustion blower 2
4 to stop and reduce the combustion air by inertia
Zero with ₂

By operating as described above, one end of fuel suddenly decreases due to vaporization delay after fire extinguishing, etc.
Even when the fuel is continuously supplied steadily, the concentration of the air-fuel mixture during the fire-extinguishing operation can be reduced and extinguished by maintaining a constant concentration from the start of the decrease in the supply amount. It is possible to obtain a control device for a combustor with less odor.

Embodiment 5 FIG. FIG. 9 is an explanatory diagram showing how fuel and combustion air are reduced when the combustor according to the fifth embodiment of the present invention is extinguished. In the case of a combustor in which the rate of decrease in fuel at the time of fire extinguishing changes as shown by the solid line in FIG. 9 due to vaporization delay or the like, or in the case of a combustion amount, the ratio of fuel and combustion air is kept constant from the start of fire extinguishing. Control is performed so that the number of revolutions changes in accordance with the decrease in fuel in accordance with the combustor and the amount of combustion. Here, the reduction rate of the fuel in FIGS. 7 and 9 is set to be the same for comparison, but when comparing the two, it is apparent that the concentration ratio between the fuel and the combustion air in FIG. 9 changes in the best state. I have. In this way, the fire can be extinguished with the concentration ratio of fuel and combustion air kept at a constant level with high accuracy, so that even in a combustor with a vaporization characteristic in which the fuel decreases in any transition, the unburned fuel can be reduced, It is possible to obtain a control device for a combustor with less odor discharged at the time of fire extinguishing.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a control device for a combustor according to the present invention.

FIG. 2 is a flowchart showing the operation of the first embodiment of the present invention.

FIG. 3 is a timing chart of voltage waveforms for explaining the operation of the first embodiment of the present invention.

FIG. 4 is a timing chart of voltage waveforms for explaining a fire extinguishing timing operation according to the first embodiment of the present invention.

FIG. 5 is a flowchart showing the operation of the second embodiment of the present invention.

FIG. 6 is a timing chart of voltage waveforms for explaining the operation of the second embodiment of the present invention.

FIG. 7 is an explanatory diagram showing how fuel and combustion air are reduced during a fire extinguishing operation according to a third embodiment of the present invention.

FIG. 8 is an explanatory diagram showing how fuel and combustion air are reduced during a fire extinguishing operation according to a fourth embodiment of the present invention.

FIG. 9 is an explanatory diagram showing how fuel and combustion air are reduced during a fire extinguishing operation according to a fifth embodiment of the present invention.

FIG. 10 is a cross-sectional view illustrating a configuration of a combustor used in a conventional liquid fuel combustion device.

FIG. 11 is an explanatory diagram showing how fuel and combustion air are reduced during a fire extinguishing operation in a conventional combustor control device.

FIG. 12 is an explanatory diagram showing how fuel and combustion air are reduced in a conventional example.

FIG. 13 is a voltage waveform diagram when braking is applied to a combustion blower in a conventional example.

FIG. 14 is an explanatory diagram showing a state of a reduction rate of fuel and combustion air when a reduction rate of combustion air is high in a conventional example.

FIG. 15 is an explanatory diagram showing a state of a decrease rate of fuel and combustion air when a decrease rate of combustion air is slow in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vaporizer 5 Flame hole 21 Fuel supply means (fuel pump) 24 Combustion blower 25 Control circuit 28 Zero cross pulse generation circuit 29 Signal generation means 31 Ignition circuit 32 Thyristor

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F23N 1/02 F23N 3/08 F23N 5/18

Claims (5)

(57) [Claims] 1. A vaporizer for vaporizing a liquid fuel, fuel supply means for supplying the liquid fuel to the vaporizer, a flame hole for burning a premixed gas of the vaporized liquid fuel and combustion air, and combustion air. A control circuit for controlling the combustion blower and the fuel supply means, a zero-cross pulse generating circuit for generating a pulse at a point where the AC power supply voltage crosses zero volts, A signal generation unit that outputs an oscillation output signal based on a pulse generated by the zero-cross pulse generation circuit, a thyristor inserted and connected between the combustion blower and the AC power supply voltage,
A firing circuit for firing the thyristor based on an oscillation output signal output from the signal generating means. In the control device for a combustor in which the concentration of the premixed gas during operation is maintained in a flammable range, a counter for counting a half cycle of the waveform of the AC power supply voltage is provided in the signal generating means, and the signal generating means is A control device for a combustor, wherein a brake is applied by applying a voltage of 1 / n which outputs only one cycle out of n cycles counted by the counter at the time of fire extinguishing to a combustion blower. 2. A vaporizer for vaporizing a liquid fuel, fuel supply means for supplying the liquid fuel to the vaporizer, a flame hole for burning a premixed gas of the vaporized liquid fuel and combustion air, and combustion air. A control circuit for controlling the combustion blower and the fuel supply means, a zero-cross pulse generating circuit for generating a pulse at a point where the AC power supply voltage crosses zero volts, A signal generation unit that outputs an oscillation output signal based on a pulse generated by the zero-cross pulse generation circuit, a thyristor inserted and connected between the combustion blower and the AC power supply voltage,
A firing circuit for firing the thyristor based on an oscillation output signal output from the signal generating means. In the control device for a combustor in which the concentration of the premixed gas during operation is maintained in a flammable range, a counter for counting a half cycle of the waveform of the AC power supply voltage is provided in the signal generating means, and the signal generating means is Of a combustor characterized in that a brake is applied by alternately applying a 1 / n voltage and a 1 / m voltage that output only one cycle out of n or m cycles counted by a counter to a combustion blower. Control device. 3. The signal generating means decelerates the combustion blower by inertia for a certain period from the start of fire extinguishing.
3. The control device for a combustor according to claim 1, wherein the voltage of 1 / n or the voltage of 1 / m is alternately applied to stop. 4. The signal generation means decelerates by applying a voltage of 1 / n or a voltage of 1 / n and 1 / m alternately to the combustion fan for a certain period from the start of fire extinguishing. The control device for a combustor according to claim 1 or 2, wherein the controller is stopped by inertia. 5. A fuel supply means for supplying liquid fuel, a combustion blower for supplying combustion air, a control circuit for controlling the combustion blower and the fuel supply means, and a fuel supply means. A vaporizer for vaporizing the liquid fuel, and a flame hole for burning a premixed gas of the liquid fuel and the combustion air vaporized by the vaporizer, wherein the control circuit controls the concentration of the premixed gas in a flammable range during a fire extinguishing operation. A combustion blower that is stopped while controlling the number of revolutions of the combustion blower so as to keep the temperature of the combustion blower constant.