JP3289408B2 - Combustion control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a burner block which achieves a low NOx reduction by rich-and-shallow combustion.
The present invention relates to a combustion control device that performs control so as to always maintain stable combustion.

[0002]

2. Description of the Related Art Conventionally, there is a combustion control apparatus of this type as shown in FIG. That is, the burner flame plate 1
A fan 4 provided on the upstream side so as to form a low m-value flame 2 and a high m-value flame 3, respectively;
A respective gas supply 5, 6 for supplying gas to each burner of value was provided. Then, based on the outputs of the respective temperature sensors 7 and 8, the low m-value flame 2 and the high m-value flame 3
Even if the same output value is shown with the excess air ratio m = 1 as a boundary, the fan 4 is controlled by discriminating to which side the output value is.

[0003]

However, in the above-mentioned conventional structure, the low m value flame 2 or rich flame and the high m value flame 3 or light flame are a reducing flame and an oxidizing flame, respectively. The environment is completely different. In particular, the low m-value flame 2 has a very low sensitivity to the mixture ratio and a very high sensitivity to the combustion amount. Therefore, there is a change in the sensitivity of the sensor over time and a difference in the life, and there is a problem in reliability. Further, it is a precondition that the combustion state of each of the low m-value flame 2 and the high m-value flame 3 is uniform, and that the output between the temperature sensors 7 and 8 is always kept in a constant relationship. Therefore, if a change occurs in one of the flames due to clogging of the flame or blockage of air supply and the balance of the sensor output is lost, the originally set amount of air is not supplied and an abnormal combustion state occurs. Furthermore, it does not mention how to deal with a change in the amount of combustion or how to deal with a change in the presence or absence of a wind or a blockage of the air supply / exhaust system.

The present invention has been made to solve the above problems, and has a low N
Even if the burner block of the rich-burn combustion that becomes Ox is subjected to a factor or disturbance that affects the combustion state, the burner block is automatically returned to a predetermined combustion set point so that optimal combustion control is always performed. The primary purpose is.

[0005] The second object is to quickly escape from the abnormal state and return to the original combustion set point when receiving a large disturbance or abnormal combustion. Is to stop.

[0006]

SUMMARY OF THE INVENTION In order to achieve the first object, the present invention provides a rich flame having a mixing ratio of fuel and air which forms a rich flame having an equivalent ratio or more, and a light flame having a mixing ratio of not more than an equivalent ratio. A light flame port to be formed, a burner block in which a plurality of light flame ports and light flame ports are alternately arranged, a rapid heat temperature sensor provided in contact with or in close proximity to the light flame port, and a light flame port provided near the light flame port And a fan for supplying combustion air to the burner block, and an output of the immediate heat temperature sensor at an optimal excess air ratio of the light flame port in advance according to the amount of combustion. A set state setting unit, a correction unit that corrects a response delay of the immediate heat temperature sensor, and a control unit that controls the fan so that a deviation between a set value of the state setting unit and an output value of the immediate heat temperature sensor is reduced. It is a thing.

In order to attain the second object, a rich flame which forms a rich flame having a mixing ratio of fuel and air equal to or more than an equivalent ratio is provided;
A light flame port that forms a light flame having an equivalent ratio or less, a burner block in which a plurality of rich flame ports and light flame ports are alternately arranged, and a rapid heat temperature sensor provided in contact with or close to the light flame port, A temperature sensor provided in the vicinity of the light flame port, a fan for supplying combustion air to the burner block, and an output of the immediate heat temperature sensor at an optimal excess air ratio of the light flame port were set in advance according to the amount of combustion. State setting means, correction means for correcting a response delay of the immediate heat temperature sensor, control means for controlling the fan such that the deviation between the set value of the state setting means and the output value of the immediate heat temperature sensor is reduced, and a temperature sensor The burner port temperature judging means for judging the output signal of the above is provided, and when the detection signal of the temperature sensor continuously exceeds a predetermined value for a set time or more, the combustion is stopped.

Further, the immediate heat temperature sensor and the temperature sensor are mounted on a light flame port which always burns when the combustion amount of the burner block is switched.

[0009]

According to the present invention, since the flame temperature of a light flame forming a light flame has a close relationship with the excess air ratio, the present invention provides a hot flame provided in contact with or close to the light flame. The temperature sensor detects the temperature of the light flame port with high sensitivity. That is, the excess air ratio can be detected by the immediate heat temperature sensor. The control means controls the fan to supply combustion air to the burner block based on the output of the rapid heat temperature sensor at the optimal excess air ratio of the light flame port predetermined by the state setting means according to the combustion amount. . Here, when a predetermined amount of air cannot be supplied due to the presence or absence of the wind or the blockage of the air supply / exhaust system, the immediate heat temperature sensor detects that the excess air ratio is different from the value determined according to the combustion amount. Will be. By taking this change, the correction means predicts and outputs a steady-state value obtained by correcting the response delay of the immediate heat temperature sensor. Then, the control means compares with the set value of the state setting means and increases or decreases the fan air flow according to the positive / negative level of the deviation so as to reduce the difference therebetween, thereby returning to the predetermined combustion state.

When the temperature of the light flame port rises abnormally due to some abnormality, the temperature sensor detects this state. If the output of the temperature sensor exceeds a predetermined value for a set time or more, the combustion is stopped to protect the combustion device. If the temperature is recovered within the set time, the output of the temperature sensor becomes equal to or less than a predetermined value, so that the combustion is continued.

[0011]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a burner and a control, and FIG. 2 shows a mounted state of a sensor. A plurality of light burners 11 for forming a light flame 10 on a light flame port 9 formed in a mountain shape and a plurality of dark burners 14 for forming a light flame 13 on a rich flame port 12 are alternately provided in parallel to constitute a burner block 15. are doing. A fan 16 for supplying combustion air is provided upstream of the burner block 15. Each light burner 11 and rich burner 14 has a solenoid valve 17 and a proportional valve 1
Nozzle 19 for ejecting and supplying fuel supplied through
Are attached. Further, on the downstream side of the light flame port 9 of the light burner 11 to which fuel is supplied from the nozzle 19 without passing through the switching valve 20, a rapid heat temperature sensor 21 which is mounted in contact with a temperature sensitive part, and a temperature sensitive part are provided. A temperature sensor 22 mounted in a space near the upstream side is provided.

The combustion control unit 23 includes a mixture ratio detection unit 24 for detecting a signal from the instantaneous heat temperature sensor 21 and an instantaneous heat temperature sensor 2.
1, a correction means 25 for correcting the detection response delay, a state setting means 26 for setting a target value of the immediate heat temperature sensor 21 in the optimum combustion state, a temperature detection section 27 for detecting a signal of the temperature sensor 22, Temperature determination means 28 for determining the mouth temperature and outputting a closing signal of the solenoid valve 17, combustion amount setting means 29 for setting the combustion amount calculated from the use condition, and proportional valve 18 according to the combustion amount setting signal. A proportional valve driver circuit 30 for controlling the applied voltage or current value;
And a fan driver circuit 32 that controls the fan 16 according to a signal from the control unit 31. The control unit 31 compares the output of the fan with the set value of the state setting unit 26 and outputs a control signal corresponding to the difference between the two. It is configured.

The combustion and control operations in the above configuration will be described. From each nozzle 19, the fuel whose flow rate is adjusted by the proportional valve 18 is jetted in a predetermined amount forming a rich and lean flame, and is mixed with the combustion air supplied from the fan 16. Here, in the light burner 11, a light mixture having an equivalence ratio or less is blown out from the light flame port 9 to form a light flame 10.
Similarly, in the rich burner 14, a rich mixture having a ratio equal to or higher than the equivalent ratio is blown out from the rich flame port 12 to form a rich flame 13. Therefore, in the entire burner block 15, the lean flame 10 and the rich flame 13 are alternately formed, and the rich and lean combustion is realized, and the low NOx combustion is achieved.

Here, the limit state in the combustion control will be described in advance with reference to FIG. When the set combustion amount changes, the optimum mixing ratio of the lean flame 10 and the rich flame 13 in consideration of the combustion limit also changes. Accordingly, the excess air ratio m of the entire burner block 15 is controlled to a value indicated by the curve J with the change of the combustion amount. When the amount of combustion is small, the light flame 10 comes closer to the light flame port 9, and when the air amount is small, the flame temperature rises.
Is subjected to abnormal heating, and a red-hot-flame region as shown in FIG. 3 is generated. On the other hand, if the air volume is too large,
0 becomes even leaner, and the fire extinguishes from the blow-off, or the rich flame 13 similarly extinguishes when the air amount further increases, so that the fire extinguishing area shown in FIG. 3 exists.

A control operation for ensuring a stable combustion state in the presence of such a combustion limit will be described. The required combustion amount is determined by the combustion amount setting means 29, and the proportional valve 18 and the fan 16 are controlled by the proportional valve driver circuit 30 and the fan driver circuit 32 to set the flow rates of the fuel and the air. It is set to the point A which is the optimal excess air ratio according to the above. Here, as shown in FIG. 4, there is a certain correlation between the excess air ratio m and the output signal of the immediate heat temperature sensor 21 for each combustion amount, and if this output signal is known, the excess air ratio m can be obtained.

The operation of the combustion apparatus when the supply / exhaust amount changes due to disturbance factors such as wind will be described with reference to FIG. When the exhaust resistance increases due to the breeze at the time t1, the excess air rate m becomes the point A as shown in FIGS.
Starts to move to point B from. At this time, light flame 10
Approaches the light flame port 9 and the temperature of the light flame port 9 rises. Since the temperature sensing part of the immediate heat temperature sensor 21 is in contact with the light flame port 10, the temperature rise can be detected relatively quickly, and the mixture ratio detection part 24 outputs the immediate heat temperature sensor output 33 according to the combustion amount. Thus, it is detected that the deviation from the predetermined set value 34 has begun. Taking this change into account, the correction means 25 outputs a correction value in consideration of the response delay of the immediate heat temperature sensor 21.
Next, the control means 31 compares the correction value of the correction means 25 with the set value of the state setting means 26, and outputs a proportional control signal of the fan 16 so that the deviation between the two becomes small. In this case, the control means 31 compares the set value 34 of the state setting means 26 with the fan driver circuit 3 so as to increase the fan rotation speed 35 because a positive deviation has occurred and to reduce the deviation to zero.
2 is controlled. As a result, the combustion set point returns from point B to point A again, and the output 33 of the immediate heat temperature sensor and the set value 34 match. When the breeze stops at the time t2, the above operation is performed in the same manner, and a negative deviation is generated this time, so that the fan rotation speed 35 is reduced. Therefore, immediately after the breeze stops, it moves from point A toward point C and returns to point A again. When the exhaust resistance increases greatly due to the strong wind at time t3, the combustion set point moves from point A to point D in the red hot region of the light flame port 9. In this case, since the deviation of the immediate heat temperature sensor output 33 is large, the correction value output from the correction means 25 is also large, and the fan speed 35 is greatly increased.

Here, the temperature of the light flame port 9 is also detected by a temperature sensor 22. The temperature sensor output 36 output from the temperature detection unit 27 has a small output level with a slightly large time delay because the temperature sensor 22 is located on the upstream side of the light flame port 9 and the temperature sensing unit is set slightly apart. Show. The temperature determination means 28 determines the time t at which the light flame outlet 9 escapes the red heat region.
It is detected that the predetermined value 37 is transiently exceeded for a time T1 from 4 to t5. In this case, the time T1 is equal to the set time T
Since the value is smaller than 0, the closing signal of the solenoid valve 17 is not output.

Here, a description will be given of a case in which a gust of wind causes a large increase in exhaust resistance and the combustion set point moves from point A to point E at once. Since the deviation between the instantaneous heat temperature sensor output 33 and the set value 34 occurs again, the correction means 25 outputs a further increase in the number of fan rotations required to return to the point A as a correction value. This requires a rotation speed exceeding the capacity limit. The fan motor driver circuit 32 keeps the fan rotation speed set to the limit value 38 to protect the fan motor. Therefore, the temperature sensor output 36 rises again and exceeds the predetermined value 37 again at time t7. Since the fan rotation speed 35 has reached the limit value 38, the temperature determination unit 28 determines from the time t7 to the time t8.
When the time T2 until the time exceeds the set time T0, the solenoid valve 17
And outputs a closing signal to stop combustion to prevent burning of the combustion device.

If the immediate heat temperature sensor 21, which is frequently exposed to high temperature, breaks, the temperature sensor 22 which is always used in the low temperature region serves as a backup to reduce the lack of air and the red heat of the light flame port 9. Detecting and stopping combustion guarantees safety.

The amount of combustion is further reduced, and there are a light burner 11 and a dark burner 14 that are extinguished by the switching valve 20 in the burner block 15, but both the immediate heat temperature sensor 21 and the temperature sensor 22 are connected to the light flame port 9 that always burns. Because it is attached,
The number of mounted sensors can be minimized.

[0021]

According to the combustion apparatus of the present invention as described in the above embodiments, the following effects can be obtained.

(1) When the combustion set point deviates from a predetermined position due to disturbance or the like, a change in the output of the heat temperature sensor is immediately detected, and a correction value is output from the correction means, and the deviation from the set value is small. By controlling the fan air volume by the control means so as to return to the original set point, it is possible to always maintain a stable low NOx combustion even if a temporary disturbance factor occurs or changes over time. Can be.

(2) Even when the combustion set point cannot be returned to the predetermined position because the correction value cannot be corrected only by the correction value of the correction means, if the air is insufficient, the temperature sensor detects the red hot state of the light flame port. Since the fuel supply is detected and the supply of fuel is stopped, abnormal combustion does not continue and safety can be guaranteed.

(3) When the light flame port starts red heat and the output of the temperature sensor exceeds a predetermined value for a set time or more, the supply of fuel is stopped, so that the light flame port is deformed or damaged. Disappears. Therefore, it is possible to use a thin plate for the material of the light flame port, and it becomes inexpensive, and the mass productivity is improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of a burner and control of a combustion control device according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of a main part of the sensor mounted in FIG.

FIG. 3 is an explanatory diagram showing a combustion limit region and a combustion set point based on a combustion amount and an excess air ratio.

FIG. 4 is an explanatory diagram showing a relationship between an immediate heat sensor output and an excess air ratio.

FIG. 5 is a time chart showing a control response due to a disturbance;

FIG. 6 is an overall sectional view of a conventional combustion control device.

[Explanation of symbols]

 9 Light Flame Port 10 Light Flame 12 Rich Flame Port 13 Rich Flame 15 Burner Block 16 Fan 21 Instant Heat Temperature Sensor 22 Temperature Sensor 25 Correction Means 26 State Setting Means 28 Flame Temperature Determination Means 31 Control Means 37 Predetermined Value

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Keijiro Kunimoto 1006 Kadoma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. In-company (72) Inventor Yoichi Kimura 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-5-187630 (JP, A) (58) Fields investigated (Int. . ^7, DB name) F23N 5/14 340 F23C 11/00 329

Claims (3)

(57) [Claims] 1. A rich flame port which forms a rich flame having a mixing ratio of fuel and air equal to or greater than an equivalent ratio, a light flame port which forms a light flame having an equivalent ratio or less, and said rich flame port and said light flame port. A plurality of burner blocks alternately arranged, a rapid heat temperature sensor provided in contact with or in close proximity to the light flame port, and combustion stopped when a predetermined value is provided near the light flame port. A temperature sensor, a fan for supplying combustion air to the burner block, and state setting means for setting an output of the immediate heat temperature sensor at an optimum excess air ratio of the light flame port in advance according to a combustion amount. A combustion unit comprising: a correction unit that corrects a response delay of the instantaneous temperature sensor; and a control unit that controls the fan so that a deviation between a set value of the state setting unit and an output value of the instantaneous temperature sensor is reduced. Control device. 2. A rich flame port which forms a rich flame having a mixing ratio of fuel and air equal to or greater than an equivalent ratio, a light flame port which forms a light flame having an equivalent ratio or less, and said rich flame port and said light flame port. A plurality of burner blocks arranged alternately; a rapid heat temperature sensor provided in contact with or in proximity to the light flame port; a temperature sensor provided in the vicinity of the light flame port; pre optimum in response to said fan and the combustion amount supplying combustion air to
State setting means for setting the output of the instantaneous temperature sensor at the excess air ratio of the light flame port, correction means for correcting a response delay of the instantaneous temperature sensor, a set value of the state setting means, and the instantaneous temperature. Control means for controlling the fan so that the deviation of the output value of the sensor is reduced, and flame opening temperature determination means for determining the output signal of the temperature sensor, the detection signal of the temperature sensor continues for a set time or more A combustion control device that stops combustion when the pressure exceeds a predetermined value. 3. The combustion control device according to claim 1, wherein the rapid heat temperature sensor and the temperature sensor are mounted on a light flame port which always burns when the burner block switches the combustion amount.