JP2958550B2 - Combustion equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion apparatus capable of preventing incomplete combustion.

[0002]

2. Description of the Related Art Conventionally, in a combustion device such as a burner facility serving as a heat source of an air conditioner, the operation of increasing or decreasing the amount of combustion is automatically controlled toward a target temperature. Is maintained at a constant ratio.

On the other hand, in these combustion devices, when abnormal quenching (fire extinguishing) occurs for some reason, the supply of fuel gas must be stopped immediately to cause unburned gas to flow out into the combustion chamber or the like, and easily exchange with air. Danger of creating explosive mixtures.

Therefore, conventionally, a predetermined safety device has been provided. FIG. 9 is a system diagram of a burner provided with such a safety device. 101 is a burner and 102 is a combustion chamber. Burner 101 is supplied with combustion air and fuel gas from lines 103 and 104, respectively. Reference numeral 105 denotes a fuel cutoff valve that opens and closes the line 104. The combustion chamber 102 is provided with a flame detector 106, which constantly detects the presence or absence of a flame, and sends a signal to a combustion monitoring relay 107. The combustion monitoring relay 107 immediately shuts off the fuel gas by the fuel shut-off valve 105 upon receiving the flame-out signal. Thereby, when the burner has extinguished, it is possible to immediately shut off the supply of the fuel gas.

[0005]

However, even though the above-mentioned safety device is effective as a countermeasure against abnormal extinction, it cannot function as a safety device against incomplete combustion and can prevent the generation of CO harmful to the human body. Can not. That is, when CO or formaldehyde or the like is generated in the combustion product due to incomplete oxidation of the combustible component, this is called incomplete combustion. The combustion reaction formula of hydrocarbon is: CxHy + ((x + y) / 4) O ₂ = xCO ₂ + (y
/ 2) Indicated by H ₂ O, excess or deficiency of oxygen supply required for combustion is largely caused by incomplete combustion. As a cause of incomplete combustion, generally, when the supply of combustion air is insufficient,
There are a case where the oxygen concentration in the combustion air is low, a case where the fuel gas is excessive, a case where the exhaust gas of the combustion exhaust is defective, a case where the combustion flame is touched at a low temperature, and a case where the temperature of the flame decreases.

An object of the present invention is to provide a combustion apparatus that can prevent abnormal operation such as incomplete combustion.

[0007]

Means for solving the above problems are as follows. That is, in the combustion apparatus including a combustor that burns fuel, and a first controller that performs proportional combustion by adjusting the fuel and the amount of combustion air supplied to the combustor to a fixed ratio, O inside
And O ₂ sensor for detecting the ₂ concentration, the detected O ₂ is set target value in advance for the concentration, a first calculator for calculating a deviation between the detection value of the O ₂ concentration and the target value, the O _Two
A second controller for correcting the combustion air amount adjusted by the first controller based on the deviation so as to set the concentration to the target value; and a unit time having a certain period and a next unit. A second computing unit that determines whether or not the tendency of the variation of the deviation at each time is the same; and, if the two trends are the same according to the determination, instructs to stop the combustion; A combustion apparatus according to a first aspect of the present invention is characterized by including a third controller for performing the correction when the two tendencies do not coincide with each other as determined by the second computing unit.

[0008] Also, an O ₂ sensor for detecting the O ₂ concentration in the exhaust gas, a CO sensor for detecting the CO concentration in the exhaust gas due to the combustion, and the O ₂ sensor corresponding to a CO concentration target value for the CO concentration. ₂ O ₂ concentration target value for the concentration is set in advance, a first calculator for calculating a deviation between the detection value of the O ₂ concentration by the O ₂ sensor and the O ₂ concentration target value, for the CO concentration A CO concentration target value is set in advance, and the CO concentration target value and C
A second calculator for calculating a deviation from the O concentration detection value, and correcting the amount of combustion air adjusted by the first controller based on the difference calculated by the first calculator. A second controller which performs a change in the deviation between the CO concentration target value and the CO concentration detection value, and the O ₂ concentration target value and the O _{(2) a} third computing unit that determines whether or not the tendency of the variation of the deviation from the concentration detection value is identical to each other; A second aspect of the present invention is a combustion apparatus including a third controller for instructing.

The difference between the variation tendency of the deviation between the CO concentration target value and the detected CO concentration value and the coincidence of the variation tendency of the deviation between the O ₂ concentration target value and the O ₂ concentration detection value are determined in advance. A third aspect of the present invention is a combustion apparatus according to the second aspect of the present invention, further comprising a fourth computing unit that determines whether or not the detected frequency is higher than a predetermined frequency.

A CO sensor for detecting the CO concentration in the exhaust gas from the combustion, an O ₂ sensor for detecting the O ₂ concentration in the exhaust gas from the combustion, and a CO sensor for the CO concentration.
Corresponding to a density target value, the O ₂ concentration target value for the O ₂ concentration is set in advance, a first for calculating a deviation between the detection value of the O ₂ concentration by the O ₂ sensor and the O ₂ concentration target value A computing unit, wherein the O ₂ concentration detection value is a CO value which is a value within a predetermined allowable range preset for the CO concentration.
If the O ₂ concentration is within the range of the preset O ₂ concentration corresponding to the concentration allowance, the first controller adjusts the O ₂ concentration to the O ₂ concentration target value. A second controller that corrects the combustion air amount based on the deviation, and when the O ₂ concentration detection value is out of the O ₂ concentration allowable value, the CO concentration detection value is A second computing unit for determining whether or not the CO concentration is within a range of the CO concentration allowable value, and instructing to stop the combustion when the CO concentration detection value is out of the CO concentration allowable value by this determination. And a third controller for performing the correction when the detected value of the CO concentration is within the range of the allowable value of the CO concentration as determined by the second computing unit. The combustion device is a fourth invention.

A CO sensor for detecting the CO concentration in the exhaust gas from the combustion, an O ₂ sensor for detecting the O ₂ concentration in the exhaust gas from the combustion, and a CO sensor for the CO concentration.
Corresponding to a density target value, the O ₂ concentration target value for the O ₂ concentration is set in advance, a first for calculating a deviation between the detection value of the O ₂ concentration by the O ₂ sensor and the O ₂ concentration target value An arithmetic unit, a second arithmetic unit that determines whether or not the tendency of the variation of the deviation between a certain unit time of a certain period and the next unit time is the same, and the two tendencies match by this determination. If not, in order to the O ₂ concentration in the O ₂ concentration target value, the combustion air amount is adjusted by the first controller, a second controller for correcting, based on the deviation If the two tendencies match according to the determination, a second computing unit that determines whether the CO concentration detection value is within the range of the CO concentration allowable value; When the CO concentration detection value is out of the range of the CO concentration allowable value, Instructs to stop the serial combustion, by the determination by the second operator, the CO concentration detected value is the CO
If the density is within the range of the density tolerance, the third correction is performed.
A fifth aspect of the present invention is directed to a combustion apparatus including the above controller.

[0012]

When the incomplete combustion occurs, the CO concentration in the combustion exhaust gas increases. Although this CO concentration can be directly detected by a CO sensor, it has a correlation with the O ₂ concentration in the combustion exhaust gas, and can also be known by detecting this O ₂ concentration. That is, large O ₂ concentration than O ₂ concentration when the CO concentration indicates the lowest value, or in accordance with smaller, CO concentration constant correlation increasing.

Therefore, for example, when the above-mentioned minimum value is O
Etc. ₂ concentration was set as a predetermined target density desired for the O ₂ concentration, a deviation between the target value and the O ₂ concentration, in order to the O ₂ concentration in the target value, adjusted by the first control unit The calculated combustion air amount is corrected based on this deviation.

It is determined whether or not the above-mentioned tendency of the variation of the deviation coincides with each of a certain unit time of a certain period and the next unit time. Despite making such corrections,
Since the CO concentration is increasing, the combustion is stopped as an abnormal operation that may cause incomplete combustion. Therefore, abnormal operation such as incomplete combustion can be prevented.

The O ₂ sensor can be used at low cost and can be used for controlling the combustion state without heat loss. However, in the first invention, the O ₂ sensor has a large dependency on the O ₂ sensor.
Depending on the state when the O ₂ sensor detects the O ₂ concentration, unnecessary stoppage of combustion may frequently occur. Therefore, in the second invention, the CO sensor is also used, and the O ₂ concentration by
Based on the detected value of the CO concentration, it is determined whether or not each of the abnormal operations can cause incomplete combustion. In any case, the combustion is stopped only when it is determined that the operation is abnormal. A situation that occurs can be prevented. At this time, according to the determination based on the detected O ₂ concentration as in the third invention, it is determined that the operation is abnormal, and according to the determination based on the detected CO concentration, the state of normal operation is changed from a predetermined frequency. If it is determined whether or not a large amount is detected, it is possible to determine the abnormality of the O ₂ sensor, so that an alarm or the like may be issued.

Further, in the O ₂ concentration value close to O ₂ concentration corresponding to when the CO concentration indicates the lowest value, even if variation in the O ₂ concentration is large, fluctuation of the CO concentration is relatively small. Conversely, as the O ₂ concentration in the value furthest from the O ₂ concentration corresponding to the lowest value of the above, the variation of CO concentration even variation is relatively small in the O ₂ concentration increases. Therefore, when the CO concentration is near the minimum value, the detection of the O ₂ concentration indirectly causes the C
By detecting the O concentration, a slight change in the CO concentration can be easily detected. Conversely, when the CO concentration is far from the minimum value, the fluctuation of the CO concentration can be easily detected by directly detecting the CO concentration.

[0017] Therefore, by using both the O ₂ sensor and the CO sensor, fourth, according to the structure as the fifth invention, the variation of CO concentration than the first invention accurately, can be reliably detected, useless It is possible to prevent a situation in which excessive combustion is stopped frequently.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a system diagram of the combustion device according to the first embodiment of the present invention. The combustion device of the present embodiment is a burner facility provided in a regenerator of an absorption refrigerator. Reference numeral 1 denotes a burner, which burns gas fuel with combustion air. Reference numeral 2 denotes a heat exchanger provided in a regenerator (not shown) of the absorption refrigerator.
The solution is heated by the heat generated by the combustion of the fuel. Reference numeral 3 denotes a fuel valve for adjusting the amount of fuel supplied to the burner 1, and reference numeral 4 denotes an air valve for adjusting the amount of combustion air supplied to the burner 1. The combustion exhaust gas generated by the combustion is discharged out of the system.
Reference numeral 8 denotes a gas supply pipe for supplying gas as fuel to the burner 1, and a fuel cutoff valve 9 is provided upstream of the fuel valve 3. Reference numeral 13 denotes a combustion air flow path, and reference numeral 10 denotes a blower that supplies combustion air to the burner 1 through the combustion air flow path 13. The combustion exhaust gas generated by the combustion of the burner 1 flows through the heat exchanger 2, cools and cools an aqueous lithium bromide solution (not shown), and is discharged from the exhaust stack 12. Exhaust stack 1
2 is an O ₂ sensor 1 for detecting the O ₂ concentration in the combustion exhaust gas.
1 is provided. The flows of the combustion exhaust gas and the combustion air are indicated by arrows in FIG.

The control device 14 performs the following control. FIG. 1 is a control block diagram of a combustion apparatus according to a first embodiment of the present invention. FIG. 3 is a flowchart of control of the combustion device according to the first embodiment of the present invention. From the combustion amount determined by the target combustion amount, the ratio is set between the fuel amount in the optimal combustion state and the combustion air amount by the ratio setting device (ratio setting calculation). The air valve 4 and the fuel valve 3 are driven by the fuel amount and the combustion air amount, and the combustion air amount is corrected as follows (air amount correction calculation).
O ₂ detected O ₂ concentration values by the sensor 11 Ox is preset optimum combustion state oxygen to maintain the target density value O
p (calculation of oxygen concentration deviation), and based on the deviation value ex by this comparison, feedback control of air amount correction is performed on the supply amount of combustion air determined by the combustion amount already determined, and finally the air valve 4 is determined.
The target concentration value Op is desirably set to an O ₂ concentration value corresponding to the lowest value of the CO concentration. As a method of obtaining ex by comparison, it may be obtained by simply subtracting Op from Ox. Further, a temporal trend may be captured by PID control or the like.

As described above, the supply amount of combustion air is corrected by the air amount correction control loop for detecting the O ₂ concentration in the exhaust gas and performing feedback control of the combustion air amount, as shown in FIG. Combustion efficiency can be maintained high in response to disturbance factors shown therein. That is, (1)
Fluctuation of oxygen content (by mass) in air per unit volume due to fluctuation of ambient temperature. (2) fuel, combustion air,
Fluctuation of the combustion air ratio with respect to the amount of fuel caused by the difference in the characteristics of the degree of opening of each valve (the supply amount of fuel and combustion air).
(3) Fluctuation in pressure of fuel gas (when gas is used as fuel). (4) Fluctuation of fuel gas components. (5) Fluctuation in heat value per unit volume of fuel gas due to fluctuation in ambient temperature.

In this embodiment, after the calculation of the oxygen concentration deviation, the calculation of the availability of combustion is performed. That is, it is determined whether or not the fluctuation tendency of the above-described deviation ex in a certain unit time Δt1 of a certain period and the next unit time Δt2 match,
If the two tendencies match according to this determination, the determination is negative, the fuel cutoff valve 9 is shut off, and the combustion of the burner 1 is stopped. If the two tendencies do not match, the flow returns to the air amount correction calculation as acceptable. FIG. 4 is a graph showing the relationship between the oxygen concentration deviation ex and time. In order to calculate the coincidence or non-coincidence of the fluctuation tendency of the deviation ex, as shown in FIG.
Derivative value of deviation ex captured as manipulated variable at time t1

[0022]

(Equation 1)

Then, the manipulated variable is output, and the differential value of the deviation ex that captures the result is

[0024]

(Equation 2)

The determination as to whether combustion is possible may be made based on whether the signs match or not, or the degree of inclination may be determined using the above-described differential value itself as a calculated value.

As in the prior art described above, also in the combustion apparatus of the present embodiment, the flame of the burner 1 is detected, and when the flame cannot be detected, the fuel gas is shut off by the fuel cutoff valve 9 and the combustion of the burner 1 is stopped. Control for stopping combustion is performed.

The operation of this embodiment will be described. In spite of the correction of the combustion air amount as described above, a unit time t1 having a certain period and a unit time t2 having the next period are constant.
If the above-mentioned tendency of the fluctuation of the deviation ex is the same, the CO concentration in the exhaust gas is increasing more and more, and the combustion is stopped as an abnormal operation that may cause incomplete combustion. Therefore, abnormal operation such as incomplete combustion can be prevented.

Next, a second embodiment of the present invention will be described. FIG. 5 is a system diagram of a combustion apparatus according to a second embodiment of the present invention. The members having the same reference numerals as those in FIG. 2 are the same as those in the first embodiment, and thus the description is omitted. In the combustion device of the present embodiment, the exhaust stack 12 is provided with a CO sensor 15 for detecting the CO concentration in the combustion exhaust gas and a control device 16. FIG. 6 is a control block diagram of a combustion apparatus according to a second embodiment of the present invention. FIG. 7 is a flowchart of the control of the combustion apparatus according to the second embodiment of the present invention. In the present embodiment, the control by the control device 16 controls O 2 in the exhaust gas.
₍₂ ) The correction of the supply amount of combustion air by an air amount correction control loop for detecting the concentration and performing feedback control of the combustion air amount is the same as in the first embodiment, and a detailed description thereof will be omitted. In the present embodiment, an appropriate concentration determination and a determination as to whether combustion is possible based on the detection of CO concentration by the CO sensor 15 are performed instead of the calculation as to whether combustion is possible in the first embodiment.

FIG. 8 is a graph showing an example of the correlation between the O ₂ concentration and the CO concentration in the exhaust gas. According to FIG.
The O ₂ concentration value close to O ₂ concentration corresponding to when the O concentration indicates the lowest value, be greater variation in the O ₂ concentration, but fluctuations in the CO concentrations is relatively small, corresponding to the lowest value of the above O ₂
As the O ₂ concentration in the value furthest from the concentration, O ₂ variation in CO concentration with variation is relatively small concentration is can be seen significantly.

In the present embodiment, the maximum value Omax of the O ₂ concentration corresponding to the allowable value of the CO concentration in the exhaust gas
( 10% in the example of FIG. 8) and the minimum value Omin ( 5% in the example of FIG. 8) are preset. In this embodiment, after the oxygen concentration deviation calculation as in the first embodiment, O by _two sensors 11 O ₂ concentration detection value Ox is within (optimum combustion range in FIG. 8) range between Omax and Omin Is determined as an appropriate density determination. When the O ₂ concentration detection value is within this range, the first value is appropriately determined, for example, by adjusting Ox to the target concentration value Op set to the corresponding O ₂ concentration value when the CO concentration indicates the lowest value. The correction of the combustion air amount is performed in the same manner as in the embodiment. Ox is Omax and Omi
When the value is out of the range with n, it is determined to be inappropriate and the CO sensor 1
5 is compared with the limit value COmax of the allowable CO concentration for this CO concentration (combustion determination). When the detected CO concentration does not exceed COmax, the same correction of the combustion air amount as in the first embodiment is performed to adjust Op to Op. However, CO
When the detected concentration exceeds COmax, the fuel cutoff valve 9 is shut off and the combustion of the burner 1 is stopped.

Note that, in the determination of the proper density in this embodiment,
As in the first embodiment, it is determined whether or not the tendency of the variation of the deviation ex in a certain unit time Δt1 of a certain cycle and the next unit time Δt2 match, and by this determination, the two trends match. In such a case, the above-described determination of whether or not combustion is possible and subsequent control may be performed as inappropriate, and if the two tendencies do not match, the determination may be made as acceptable and the process may return to the air amount correction calculation.

Next, the operation of this embodiment will be described.
As described above, the O ₂ concentration value close to O ₂ concentration corresponding to when the CO concentration indicates the lowest value, even if variation in the O ₂ concentration is large, fluctuation of the CO concentration is relatively small. Conversely, as the O ₂ concentration in the value furthest from the O ₂ concentration corresponding to the lowest value of the above, the variation of CO concentration even variation is relatively small in the O ₂ concentration increases. Therefore, when the CO concentration is near the minimum value, a slight change in the CO concentration can be easily detected by indirectly detecting the CO concentration by detecting the O ₂ concentration. Conversely, when the CO concentration is far from the minimum value, the fluctuation of the CO concentration can be easily detected by directly detecting the CO concentration. Therefore, according to the second embodiment, it is possible to detect the fluctuation of the CO concentration more accurately and more reliably than in the first embodiment, and it is possible to prevent a situation in which unnecessary stoppage of combustion occurs frequently.

The calculation of whether or not combustion can be performed in this case may be performed as follows. That is, similarly to the above-described embodiment, it is determined whether or not the tendency of the fluctuation of the deviation ex in a certain unit time Δt1 of a certain cycle matches the next unit time Δt2. Further, a predetermined CO concentration target value and C at a certain unit time Δt1 and a next unit time Δt2 of a certain cycle are set.
It is also determined whether or not the tendency of the deviation from the detected value of the CO concentration by the O sensor 15 matches. The deviation between the CO concentration target value and the CO concentration detection value may be obtained by simple subtraction, as in the case of obtaining the above-described deviation ex, or a temporal trend may be captured. As a result of this determination, when the respective tendencies coincide, the fuel cutoff valve 9 is shut off, and the combustion of the burner 1 is stopped. Alternatively, it may be configured such that it is determined whether or not such a tendency coincidence is detected more than a predetermined frequency, and the combustion of the burner 1 is stopped when the frequency is detected. The determination as to whether or not the frequency is detected more than the predetermined frequency can be made based on, for example, whether or not the frequency is detected a predetermined number or more within a predetermined time.

With such a configuration, the following operation is achieved. The O ₂ sensor can be used at low cost and can be used for controlling the combustion state without heat loss. However, in the first embodiment, the O ₂ sensor 11 is highly dependent on the O ₂ sensor 11. Depending on the state at the time of detecting the O ₂ concentration, unnecessary stoppage of combustion of the burner 1 may frequently occur. However, according to the above configuration, the CO sensor 15 is also used, and based on the detected values of the O ₂ concentration and the CO concentration by both the sensors 11 and 15, it is determined whether or not each of the abnormal operations can cause incomplete combustion. In any case, since the combustion is stopped only when it is determined that the operation is abnormal, it is possible to prevent a situation in which unnecessary combustion is frequently stopped. According to the determination based on the detected O ₂ concentration, it is determined whether the operation is abnormal, and according to the determination based on the detected CO concentration, it is determined whether or not the state of normal operation is detected more than a predetermined frequency. If
As a result, the abnormality of the O ₂ sensor 11 can be determined, so that an alarm or the like may be issued.

In any of the embodiments, the amount of combustion air may be adjusted by inverter control of the blower 10 instead of adjusting the air valve 4.

[0036]

According to the present invention described above, it is possible to provide a combustion apparatus capable of preventing abnormal operation such as incomplete combustion.

[Brief description of the drawings]

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

FIG. 2 is a system diagram of a combustion device according to a first embodiment of the present invention.

FIG. 3 is a flowchart of control of the combustion device according to the first embodiment of the present invention.

FIG. 4 is a graph showing a relationship between an oxygen concentration deviation and time in control of the combustion device according to the first embodiment of the present invention.

FIG. 5 is a system diagram of a combustion apparatus according to a second embodiment of the present invention.

FIG. 6 is a control block diagram of a combustion apparatus according to a second embodiment of the present invention.

FIG. 7 is a flowchart of control of a combustion device according to a second embodiment of the present invention.

FIG. 8 is a graph showing an example of the correlation between the O ₂ concentration and the CO concentration in the exhaust gas.

FIG. 9 is a system diagram of a conventional burner facility provided with a safety device.

[Explanation of symbols]

1 burner 3 fuel valves 4 air valve 9 fuel cutoff valve 11 O ₂ sensors 14, 16 the control device 15 CO sensor

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F23N 5/00 F23N 1/02 F23N 5/24 107

Claims (5)

(57) [Claims] 1. A combustion system comprising: a combustor for burning fuel gas; and a first controller for proportionally burning the fuel and the amount of combustion air supplied to the combustor at a constant ratio. In the apparatus, an O ₂ sensor for detecting the O ₂ concentration in the exhaust gas and a target value for the detected O ₂ concentration are set in advance, and a deviation between the target value and the detected value of the O ₂ concentration is calculated. A second arithmetic unit that corrects the combustion air amount adjusted by the first controller based on the deviation so as to set the O ₂ concentration to the target value;
A second computing unit that determines whether or not the tendency of the variation of the deviation between a certain unit time of a fixed period and the next unit time is the same; And a third controller for instructing to stop the combustion and performing the correction when the two tendencies do not match according to the determination by the second computing unit. . 2. A combustion system comprising: a combustor for burning fuel gas; and a first controller for proportionally burning the gas supplied to the combustor and the amount of combustion air at a fixed ratio. An O ₂ sensor for detecting an O ₂ concentration in the exhaust gas, a CO sensor for detecting a CO concentration in the exhaust gas by the combustion, and the O ₂ concentration corresponding to a CO concentration target value for the CO concentration. O ₂ concentration target value for the preset, the first calculator for calculating a deviation between the detection value of the O ₂ concentration by the O ₂ sensor and the O ₂ concentration target value,
A second computing unit that presets a CO concentration target value for the CO concentration and calculates a deviation between the CO concentration target value and a CO concentration detection value obtained by the CO sensor;
A second controller for correcting the combustion air amount adjusted by the controller based on the deviation calculated by the first calculator, a unit time having a fixed period and a next unit time, It is determined whether the tendency of the variation between the CO concentration target value and the CO concentration detection value and the variation tendency of the deviation between the O ₂ concentration target value and the O ₂ concentration detection value match each other. And a third computing unit that performs
A combustion apparatus, comprising: a third controller that instructs stop of the combustion when the respective tendencies coincide with each other. 3. A difference in the tendency of the variation of the deviation between the CO concentration target value and the CO concentration detection value, a match for the tendency of variation of the deviation between the O ₂ concentration detected value and the O ₂ concentration target value ,
3. The apparatus according to claim 2, further comprising: a fourth computing unit that determines whether the frequency is detected more than a predetermined frequency.
Item 3. The combustion device according to item 1. 4. A combustion system comprising: a combustor for burning a fuel gas; and a first controller for proportionally burning the gas supplied to the combustor and the amount of combustion air at a fixed ratio. In the apparatus, a CO sensor for detecting the CO concentration in the exhaust gas due to the combustion, an O ₂ sensor for detecting the O ₂ concentration in the exhaust gas due to the combustion, and a C for the CO concentration
Corresponding to O density target value, the O ₂ concentration target value for the O ₂ concentration is set in advance, the O ₂ and the O ₂ concentration target value
The first to calculate the deviation from the O ₂ concentration detected by the sensor
And the O ₂ concentration detection value is a value within a predetermined allowable range preset for the CO concentration.
When the O ₂ concentration is within the range of the preset O ₂ concentration corresponding to the O concentration allowance, the first controller adjusts the O ₂ concentration to the O ₂ concentration target value. A second controller that corrects the combustion air amount based on the deviation, and when the O ₂ concentration detection value is out of the O ₂ concentration allowable value, the CO concentration detection value A second computing unit that determines whether or not the CO concentration is within a range of the CO concentration allowable value; and, if the CO concentration detection value is out of the CO concentration allowable value, the stop of the combustion is determined. And a third controller for performing the correction when the CO concentration detection value is within the range of the CO concentration allowable value as determined by the second computing unit. Burning device. 5. A combustion system comprising: a combustor that burns fuel gas; and a first controller that performs proportional combustion by adjusting the gas supplied to the combustor and the amount of combustion air to a fixed ratio. In the apparatus, a CO sensor for detecting the CO concentration in the exhaust gas due to the combustion, an O ₂ sensor for detecting the O ₂ concentration in the exhaust gas due to the combustion, and a C for the CO concentration
Corresponding to O density target value, the O ₂ concentration target value for the O ₂ concentration is set in advance, the O ₂ and the O ₂ concentration target value
The first to calculate the deviation from the O ₂ concentration detected by the sensor
And a second computing unit that determines whether or not the tendency of the variation of the deviation between a certain unit time of a certain period and the next unit time is the same, and the two tendencies match by this determination. If not, a _second controller that corrects the combustion air amount adjusted by the first controller based on the deviation so that the O ₂ concentration becomes the O ₂ concentration target value. And a second computing unit that determines whether the CO concentration detection value is within the range of the CO concentration allowable value, when the two trends match according to the determination, When the CO concentration detection value is out of the range of the CO concentration allowable value, the stop of combustion is instructed, and the CO concentration detection value is determined by the second computing unit to be equal to the C concentration.
A third controller for performing the correction when the O concentration is within the allowable range.