JP3740724B2 - Combustion control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a burner apparatus that heats water, air, etc. by burning fuel such as gas or petroleum, and more particularly to a combustion control apparatus that performs A / F control based on component detection for exhaust gas from the burner apparatus. is there.
[0002]
[Prior art]
Conventionally, this type of fuel control device is generally as shown in Japanese Patent Laid-Open No. 5-215329. Hereinafter, the configuration will be described with reference to FIGS. In the combustion control method of the combustion apparatus for burning the fuel supplied to the burner 1 using the air taken in by the rotation of the fan 2, a combustion sensor 3 for detecting the combustion state is provided on the exhaust side of the exhaust gas. A reference level of the combustion state is set corresponding to the fuel supply amount, and the detection level is set when the detection level detected by the combustion sensor 3 exceeds the reference level corresponding to the combustion supply amount to the abnormal side. The fan speed was controlled to increase or decrease in the direction to return to the normal side.
[0003]
[Problems to be solved by the invention]
However, in the conventional combustion control device, in the range of use conditions in which the instrument specifications, for example, the gas type to be supplied is set in advance at the factory shipment stage, the combustion with good A / F setting against disturbance such as wind The optimal combustion state can be achieved by detecting the departure from the set range with a CO sensor and correcting the fan speed. However, if the supplied gas type is different from that set in the factory at the factory, If there is a change in the gas type component, the correction of the fan speed in the combustion setting range better than the initial A / F setting will take time, and incomplete combustion will occur during that time. Or, there was a problem that the correction of the fan rotation speed does not operate normally.
[0004]
The present invention solves the above-mentioned conventional problems, and supplies without incomplete combustion when the specification of the instrument, for example, when the type of gas to be supplied is changed or when the component of the gas type varies. An object of the present invention is to provide a combustion control device that performs A / F setting optimal for the gas to be used.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, the present invention is located on the upstream side of the flaming body, mixing a fuel and air, a fuel regulator for adjusting fuel, and connecting to the fuel regulator to face the mixing chamber. A fuel nozzle, a combustion fan that faces the mixing chamber and sends combustion air, a CO sensor that detects the CO concentration of exhaust gas from the flame port body downstream of the flame port body, and a fuel based on the output from the CO sensor It consists of a controller and a controller that controls the combustion fan. This controller gives A / F control as standard settings, for example, the blast volume and fuel supply volume of the combustion fan corresponding to the standard gas type, and detects the CO concentration, and the CO concentration is predetermined. If it is lower than the value, the air flow rate is reduced and the increase or decrease in the CO concentration is detected. If it increases, the air flow rate is reduced until the predetermined value of the CO concentration is reached, and the lower limit air flow rate is recorded. The amount of air flow obtained by adding the preset adjustment air amount is set as a normal A / F control, and when the detected value of increase / decrease in CO concentration decreases, the amount of air flow is increased until the predetermined value of CO concentration is reached, The upper air flow rate is recorded, and the air flow rate obtained by subtracting the preset air flow rate in advance from the upper air flow rate is set as a normal A / F control set value.
[0006]
In order to improve the detection accuracy of the blast volume, an air volume sensor is provided at the combustion fan outlet or the combustion fan inlet, and the output is input to the controller.
[0007]
In addition, in order to obtain the excess air ratio of the exhaust gas from the oxygen concentration in the exhaust gas and improve the detection accuracy of the blown air volume, an oxygen sensor is provided downstream of the flame port body and the output is input to the controller. It is.
[0008]
In addition, in order to improve the CO concentration detection accuracy in the exhaust gas, an exhaust gas recirculation path having a plurality of exhaust gas intakes on the downstream side of the flame port body and an exhaust port at the suction port of the combustion fan is provided. A CO sensor is provided in the gas recirculation path.
[0009]
In addition, a test run circuit is provided to verify the gas type only when installing the instrument or periodically.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The combustion control device of the present invention has the above-described configuration, the fuel adjusted by the fuel regulator and ejected from the fuel nozzle and the air discharged from the combustion fan that sends the combustion air are mixed in the mixing chamber, and then supplied to the flame mouth body. The CO concentration in the exhaust gas is detected by a CO sensor that is ignited and burned downstream of the flame mouth body and is installed on the downstream side of the flame mouth body. The controller is given the initial setting of the blower volume and fuel supply volume of the combustion fan corresponding to the standard gas type, A / F controls the combustion fan and fuel regulator, and the detection level detected by the CO sensor is When it is lower than the predetermined value, the amount of blown air is reduced and the increase or decrease in CO concentration is detected. When the CO concentration increases, the air flow rate is reduced until the CO concentration reaches a predetermined value, the lower limit air flow rate is recorded, and the air flow rate obtained by adding the preset air flow rate to the lower limit air flow rate is the initial setting A / F. Since the control value is changed to the new normal A / F control value, the combustion state can be burned from the incomplete combustion on the air-deficient side with a sufficient amount of adjustment air flow. Even when the CO concentration decreases, the air flow rate is increased until the CO concentration reaches a predetermined value, the upper air flow rate is recorded, and the air flow rate obtained by subtracting the preset air flow rate from the upper air flow rate is set to the initial setting A / Since the setting value of the F control is changed to a new setting value of the normal A / F control, the combustion state can be burned from the incomplete combustion on the excess air side with a sufficient amount of adjustment air flow.
[0011]
In addition, since the supply amount of combustion air can be detected by the air volume sensor, the air flow rate can be detected more accurately than when the air flow rate is estimated and calculated by the combustion fan rotation speed, and the set value accuracy of the A / F control can be improved. Can be improved.
[0012]
In addition, the oxygen concentration in the exhaust gas is detected by an oxygen sensor provided on the downstream side of the flame mouth body, and the excess air ratio of the exhaust gas is calculated, so that the combustion state and the blown air volume can be accurately detected, and A / F control The set value accuracy can be improved.
[0013]
Further, the plurality of exhaust gas intakes averages the CO concentration distribution in the combustion chamber and sucks the exhaust gas, and the exhaust gas is sucked into the combustion fan via the CO sensor in the exhaust gas recirculation path. The detection value of the CO sensor is highly accurate.
[0014]
Further, by providing a test operation circuit, the set value of the A / F control can be updated only during the test operation of the instrument or when the gas type is changed, and the amount of combustion that occurs when the set value of the A / F control is calculated. The problem of hot water temperature control due to fixing can be solved.
[0015]
In the following, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a configuration diagram of a combustion control apparatus according to a first embodiment of the present invention, in which fuel adjusted by a fuel regulator 4 and ejected from a fuel nozzle 5 and air discharged from a combustion fan 6 for sending combustion air are shown. After mixing in the mixing chamber 7, the flow is rectified by the honeycomb lattice 8 and supplied to the flame opening body 9. After the air-fuel mixture burns in the combustion chamber 10, it passes through the heat exchanger 11 and the exhaust gas passage 12 and is discharged from the exhaust port 13. The CO sensor 14 is attached in the exhaust gas passage 12. Furthermore, the controller 15 controls the fuel regulator 4 and the combustion fan 6 to ignite downstream of the flame opening body 9 to form a flame and maintain stable combustion.
[0016]
Here, the operation of the controller 15 in the combustion control device will be described with reference to FIGS. The combustion control apparatus that has started operation starts A / F control with an A / F control set value as an initial set value corresponding to a preset standard specification, for example, standard gas. The A / F control set value here is the amount of blown air and the amount of combustion, the amount of blown air is the fan speed of the combustion fan 6, and the amount of combustion is the opening of the fuel regulator 4.
[0017]
After the A / F control is started, the CO concentration in the exhaust gas is detected by the CO sensor 14, and the detected value is compared with a predetermined value that is a CO generation allowable value. When the detected value is larger than the predetermined value, it is assumed that incomplete combustion has occurred for some reason, the operation is stopped, and an abnormality of the device is displayed and alarmed. When the detected value is smaller than the predetermined value, the amount of blown air is reduced and the increase / decrease in the CO concentration is detected. When the CO concentration increases, as shown in FIG. 3A, the air flow rate is reduced until the CO concentration detection value reaches a predetermined value that is the CO generation allowable value, and the CO concentration detection value is equal to the predetermined value. A / F control is performed by recording the air volume as the lower limit air volume and using the air flow value obtained by adding the adjusted air volume to the lower air volume as a new A / F control set value. The adjusted blast volume is a value determined in advance from the combustion performance of the combustion device to be used, and is selected so that the combustion state can be combusted with an appropriate margin from the incomplete combustion on the air shortage side. When the CO concentration decreases, as shown in FIG. 3 (b), the air flow rate is increased until the CO concentration detection value reaches a predetermined value that is the CO generation allowable value, and when the CO concentration detection value becomes equal to the predetermined value, The A / F control is performed by recording the air volume as the upper limit air volume and using the air flow value obtained by subtracting the adjusted air volume from the upper air volume as a new A / F control setting value.
[0018]
The adjusted blast volume is a value determined in advance from the combustion performance of the combustion apparatus to be used, and is selected so that the combustion state can be combusted with an appropriate margin from incomplete combustion with excess air.
[0019]
According to the first embodiment of the present invention, the A / F control set value is continuously set to the point where the combustion state of the appliance is optimum, so that the gas type supplied to the appliance is changed or the gas Gas that is supplied without causing incomplete combustion even when there is a variation in the components of the seeds, and even when the fins of the heat exchanger 11 are obstructed or the blast volume of the combustion fan 6 is reduced due to aging of the equipment. A / F setting that is optimal for the above can be performed.
[0020]
Next, a second embodiment of the present invention will be described with reference to FIG. The second embodiment is different from the first embodiment in that an averaging circuit 16 is provided. The averaging circuit 16 calculates the blast volume after averaging the adjusted blast volume, the lower limit blast volume, and the upper limit blast volume for a predetermined period that is determined to be optimal in advance, and calculates variations in the blast volume due to disturbance such as wind. Therefore, the reliability of the A / F control set value can be improved.
[0021]
Next, a third embodiment of the present invention will be described with reference to FIG. The third embodiment is different from the first embodiment in that an air volume sensor 17 is provided at the outlet of the combustion fan 6 or the inlet of the combustion fan 6 and the output is input to the controller 15. It is that. Since the air volume sensor 17 can directly detect the supply amount of the combustion air, it can accurately detect the air volume compared to estimating and calculating the air volume based on the rotational speed of the combustion fan as in the first embodiment. Errors due to disturbances such as wind can be eliminated, and the set value accuracy of A / F control can be improved. In addition, since the relationship between the fan speed and the air flow rate can be verified, when the fan speed gradually increases with respect to the air flow rate, it is possible to detect that an abnormality such as clogging of dust has occurred in the air supply / exhaust path of the appliance. It is possible to predict, display, alarm, etc. of equipment failure.
[0022]
Next, a fourth embodiment of the present invention will be described with reference to FIG. The fourth embodiment differs from the first embodiment in that an oxygen sensor 18 is provided on the downstream side of the flame opening body 9 and its output is input to the controller 15. By detecting the oxygen concentration in the exhaust gas and calculating the excess air ratio of the exhaust gas regardless of the gas type, the blast amount is estimated and calculated based on the rotational speed of the combustion fan as in the first embodiment. Compared to the above, the amount of blown air can be detected accurately, errors due to disturbance such as wind can be reduced, and the set value accuracy of A / F control can be improved. Also, compared with the case where the amount of blast before combustion is verified as in the third embodiment, the amount of blast is calculated from the exhaust gas component after actual combustion, so the blast leaked in the mixing chamber 7 and the like. Even in this case, the amount of air used for combustion can be accurately detected, the combustion state can be directly monitored, and the instrument can be controlled safely.
[0023]
Next, a fifth embodiment of the present invention will be described with reference to FIG. The fifth embodiment is different from the first embodiment in that a plurality of exhaust gas intakes 20 are provided in the exhaust gas passage 12 at appropriate intervals, and the CO concentration distribution in the exhaust gas passage 12 is averaged. The exhaust gas is sucked in, and the exhaust gas is sucked into the combustion fan 6 from the exhaust port 23 via the CO sensor 22 provided in the exhaust gas recirculation path 21. Therefore, the detection level of the CO sensor can be made substantially coincident with the CO concentration level in the total exhaust gas, so that the detection value of the CO sensor 22 becomes highly accurate, and the A / F control that is calculated based on that value is used. There is an effect of improving the reliability of the set value. Moreover, NOx of the flame formed in the flame opening body 9 by exhaust gas recirculation can be reduced.
[0024]
Finally, a sixth embodiment of the present invention will be described with reference to FIG. The sixth embodiment is different from the first embodiment in that a test run circuit 24 is provided. Originally, A / F control setting values are updated when new components are installed, when the components of the gas species to be supplied are changed, or when each actuator deteriorates from its initial state due to changes over time, etc. Therefore, it is not necessary to change the set value of the A / F control during normal operation. Therefore, the test operation circuit 24 prevents the A / F control set value operation from being performed during normal operation by updating the set value of the A / F control only during the test operation of the instrument, the gas type change, and the periodic inspection. By prioritizing other controls such as A / F control and hot water temperature control, the processing capacity of the controller 15 can be used effectively. Further, when calculating the set value of A / F control, it is necessary to obtain the set value by fixing the combustion amount at the two A / F set points, that is, the maximum combustion amount and the minimum combustion amount. When the amount is fixed, problems such as inability to control hot water temperature occur. However, if this is done at the time of trial operation, it is not the time of actual use, so there is no need to consider hot water temperature control and the like, and usability is improved.
[0025]
【The invention's effect】
As is apparent from the above description, the combustion control device of the present invention provides the following effects.
[0026]
(1) Since the set value of A / F control is continuously set to the optimum point of the combustion state, when the gas type supplied to the instrument is changed or when the component of the gas type varies, In addition, the optimum A / F setting can be performed without causing incomplete combustion even with respect to a decrease in the amount of blown air due to aging of the appliance.
[0027]
(2) Since the air flow sensor can directly detect the supply amount of combustion air, it can detect the air flow rate more accurately than the estimation of the air flow rate based on the rotation speed of the combustion fan. And the set value accuracy of A / F control can be improved. In addition, since the relationship between the fan speed and the air flow rate can be verified, when the fan speed gradually increases with respect to the air flow rate, it is possible to detect that an abnormality such as clogging of dust has occurred in the air supply / exhaust path of the appliance. It is possible to predict, display, alarm, etc. of equipment failure.
[0028]
(3) Since the amount of blown air is calculated from the exhaust gas component after the actual combustion by detecting the oxygen concentration in the exhaust gas, the amount of blown air used for combustion even when the air is leaked along the way Can be calculated from the excess air ratio of the exhaust gas, so that the amount of blown air can be accurately detected, and the set value accuracy of the A / F control can be improved. In addition, the combustion state can be directly monitored, and the instrument can be controlled safely.
[0029]
(4) By changing the position of the CO sensor to the exhaust gas recirculation path, the detection level of the CO sensor can be made substantially coincident with the CO concentration level in all exhaust gases, and A / F control calculated based on that value The reliability of the set value can be improved.
[0030]
(5) Prioritize other controls such as A / F control and hot water temperature control by updating the set value of A / F control only during the trial run of the instrument, when changing the gas type, and during periodic inspections. The processing capacity of the controller can be used effectively. In addition, problems with hot water temperature control and the like caused by fixing the combustion amount generated when setting A / F control can be solved.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a combustion control device according to a first embodiment of the present invention. FIG. 2 is a flowchart of a control device according to the same embodiment. FIG. Explanatory diagram showing adjusted air flow rate and A / F setting (b) Explanatory diagram showing upper limit air flow rate, adjusted air flow rate, and A / F setting in the same embodiment FIG. 4 in the second embodiment of the present invention FIG. 5 is a block diagram of a combustion control device according to a third embodiment of the present invention. FIG. 6 is a block diagram of a combustion control device according to a fourth embodiment of the present invention. FIG. 8 is a configuration diagram of a combustion control apparatus according to a fifth embodiment of the present invention. FIG. 8 is a configuration diagram of a combustion control apparatus according to a sixth embodiment of the present invention. Fig. 10 Flow chart of the combustion control system [Explanation of symbols]
DESCRIPTION OF SYMBOLS 4 Fuel regulator 5 Fuel nozzle 6 Combustion fan 7 Mixing chamber 9 Flame port body 14 CO sensor 15 Controller 17 Air volume sensor 18 Oxygen sensor 20 Exhaust gas intake 21 Exhaust gas recirculation path 22 CO sensor 23 Exhaust port 24 Test run circuit

Claims (5)

  A mixing chamber that is located upstream of the flaming body and mixes fuel and air; a fuel regulator that regulates fuel; a fuel nozzle that is connected to the fuel regulator and faces the mixing chamber; and a combustion that faces the mixing chamber A combustion fan for sending air; a CO sensor for detecting the CO concentration of the exhaust gas from the flame mouth body downstream of the flame mouth body; and the fuel regulator and the combustion fan based on an output from the CO sensor. The controller is provided with an initial setting of the blower amount and fuel supply amount of the combustion fan corresponding to the standard gas type, performs A / F control, detects the CO concentration, and detects CO concentration. When the concentration is lower than the predetermined value, the air flow rate is decreased to detect the increase or decrease in the CO concentration. When the concentration is increased, the air flow rate is decreased until the CO concentration reaches the predetermined value, and the lower limit air flow rate is recorded. Set the lower limit air flow in advance When the detected airflow increase / decrease value is decreased, the airflow is increased until the predetermined value of CO concentration is reached, and the upper limit is set. A combustion control device that records the air flow rate and sets the air flow rate obtained by subtracting the preset air flow rate to the upper limit air flow rate as a set value for normal A / F control. The combustion control device according to claim 1 , wherein an air volume sensor is provided at a combustion fan outlet or a combustion fan inlet, and an output thereof is input to a controller. The combustion control device according to claim 1 or 2 , wherein an oxygen sensor is provided on the downstream side of the flame opening body and an output thereof is input to the controller. The intake plurality of exhaust gas on the downstream side of the burner port body is provided with an exhaust gas recirculation passage with an outlet to the inlet of the combustion fan, according to claim 1, wherein the decor CO sensor in the exhaust gas recirculation Or the combustion control apparatus of 3 . The combustion control device according to claim 1, 2, 3, or 4, further comprising a test operation circuit that activates a control operation of the controller only during a test operation of the instrument.

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