JPH0777327A - Soot clogging detection method for combustion device and co sensor trouble detection method for co sensor equipped combustion device based on the method - Google Patents

Abstract

PURPOSE:To make it possible to detect soot clogging in automatic mode by monitoring arithmetic operations of thermal efficiency one after another based on temperature information of a heating medium on the input and output of a heat exchanger and a flow rate of a heating medium and the supply of fuel and determining that a combustion device is clogged with soot, if the computed value drops to a specified value or blow. CONSTITUTION:When operating hot water supply heater or the like, thermal efficiency during combustion operation of a burner 1 is determined from the following equation: Thermal efficiency=effective amount of heat/amount of supplied heat-lambdaX (outside temperature-input temperature) X flow rate/(alphaX fuel supply) based on information about input temperature, output temperature, supply and flow rate of fuel in terms of a thermal efficiency arithmetic operation unit 24 where lambda stands for a specific heat a heating medium, while alpha stands for amount of heat per unit volume. Then, a stabilization determinant unit 25 compares a preceding thermal efficiency with the latest thermal efficiency and when this difference between both values is small than an allowable range when the thermal efficiency is stabilized), an average thermal efficiency is determined by an average thermal efficiency computation unit 27. When this average thermal efficiency exceeds an allowable deviation value and drops below that, it is determined that the heat exchanger 2 is clogged with soot so that an annunciation unit 29 is operated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soot clogging detection method for a combustion device such as a water heater or a heater, and a CO sensor failure detection method for a combustion device with a CO sensor using the method.

[0002]

2. Description of the Related Art Recently, in order to miniaturize a combustion apparatus such as a water heater, a bath heater, or a heater that uses gas or oil as a fuel, a combustion fan is provided in the apparatus to reduce the amount of fuel. The combustor is forcedly burned by supplying the burner with an amount of air commensurate with. However, if the combustion fan does not supply the burner with an amount of air commensurate with the amount of fuel, and the balance between the amount of fuel and the amount of air is lost, partial incombustion easily occurs, and once partial incombustion occurs, soot rapidly increases in the heat exchanger. There is a risk that they will adhere and lead to a fire. An example of occurrence of partial incombustion due to the imbalance of the fuel amount and the air amount is shown in FIGS. 5 and 6.

FIG. 5 shows a water heater of the type in which the combustion fan 3 is arranged on the exhaust side. When such a water heater is installed on a dusty ground or the like, the burner 1 is used. The dust is sucked from the air port of the burner 1, and the dust is accumulated inside the flame port 1a of the burner 1 as shown in the figure. Therefore, the air supplied to the burner 1 is not uniform, and the balance between the air amount and the fuel amount is lost. Partial non-combustion occurs at a portion where dust is attached to the burner 1 burner 1, soot is rapidly attached to the heat exchanger 2, and soot clogging occurs.

FIG. 6 shows a water heater of the type in which the combustion fan 3 is arranged on the air supply side. In such a water heater, punching metal is provided between the combustion fan 3 and the burner 1. By interposing the pressure equalizing plate 4 such as the above, the air from the combustion fan 3 is evenly divided and the air is supplied to each part of the burner 1. In this case, the suction force due to the rotation of the combustion fan 3 is strong and the intake port 3a
Insects such as mosquitoes and moths are sucked in from the pressure equalizing plate 4
As a result, air is not evenly supplied to the burner 1 to cause partial incombustion, and soot is clogged in the heat exchanger 2 as described above.

Partial incombustion occurs as described above, and the heat exchanger 2
When soot clogging occurs, there is no conventional method for detecting this, and the user of the combustion device has no choice but to rely on human senses, such as notice of dirt on the soot around the device or a strange odor during combustion. On the other hand, a CO sensor is provided in the combustion device, the CO sensor detects the CO gas in the exhaust gas, and an alarm device is activated when the detected CO concentration reaches a predetermined reference concentration. In the combustion device with a CO sensor provided with the CO safety device for performing the CO safety operation, the CO detection concentration reaches the reference concentration due to the partial incombustibility as described above, and therefore the CO safety operation by the CO sensor is performed. But C
If the O sensor fails, CO safe operation cannot be performed, so that partial incombustibility is left unattended, which may lead to a disaster, which is very dangerous.

[0006]

However, it is extremely dangerous to rely solely on the human sense to judge the soot clogging,
A combustion device having a function of automatically detecting this is desired.

Further, in the combustion device with a CO sensor,
If the soot clogging of the heat exchanger can be detected automatically, even if the soot clogging is detected, if the CO safety operation by the CO sensor is not performed, the failure of the CO sensor will be detected, resulting in incompleteness. Accidents due to combustion can be prevented.

The present invention has been made to solve the above problems, and an object thereof is to detect soot clogging of a combustion device which can automatically detect soot clogging of a heat exchanger without relying on human senses. A method and a method for detecting a CO sensor failure in a combustion apparatus with a CO sensor using the method.

[0009]

In order to achieve the above object, the present invention is constructed as follows. That is, the present invention burns the fuel supplied to the burner using the air taken in by the rotation of the combustion fan, and detects the soot clogging of the combustion device that heats the heating medium passing through the heat exchanger with this combustion thermal power. In this method, information including the temperature information of the heating medium on the inlet side and the outlet side of the heat exchanger, the fuel supply amount, and the flow rate of the heating medium is taken in, and the thermal efficiency is sequentially calculated and monitored during the burner combustion operation. , The soot clogging is detected by comparing with the value of the reference thermal efficiency given in advance and judging that the soot clogging of the heat exchanger has occurred when the calculated value of the thermal efficiency is lower than the value of the reference thermal efficiency by a predetermined allowable deviation. A method for detecting a CO sensor failure in a combustion apparatus with a CO sensor according to the present invention, which is configured to output a signal, detects the CO concentration in exhaust gas in the combustion apparatus. A CO sensor and a CO safety device that performs a CO safety operation when the CO detected concentration of the CO sensor reaches a predetermined reference concentration, and a calculated value of thermal efficiency calculated by the method according to claim 1 is given in advance. It is configured to output a failure detection signal of the CO sensor when the value is lower than a predetermined reference thermal efficiency value by a predetermined allowable deviation.

[0010]

[Operation] From the information on the temperature of the heating medium on the inlet side and the outlet side of the heat exchanger, the fuel supply amount, and the information on the flow rate of the heating medium,
The thermal efficiency during burner combustion operation is sequentially monitored, and when the calculated value of this thermal efficiency falls below a predetermined allowable deviation from the value of the reference thermal efficiency which is the thermal efficiency when there is no soot clogging, the combustion device It is judged that there was soot clogging, and a soot clogging detection signal is output.

Further, in the combustion device with a CO sensor, in which the CO sensor performs a CO safe operation when the CO concentration in the exhaust gas reaches the reference concentration, even if soot clogging is detected as described above, the CO sensor detects When the CO safe operation is not performed, the failure of the CO sensor is detected.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show a first embodiment for carrying out a soot clogging detection method for a combustion apparatus according to the present invention and a CO sensor failure detection method for a combustion apparatus with a CO sensor using the method.

FIG. 2 shows a system configuration of a water heater in which the heating medium is water as the combustion apparatus in this embodiment. In the figure, a water supply pipe 6 is connected to the inlet side of the heat exchanger 2, and an inlet side thermistor 8 for detecting the water entrance temperature and a flow rate sensor 9 for detecting the water flow rate are connected to the water supply pipe 6. It is provided. A hot water supply pipe 7 is connected to the outlet side of the heat exchanger 2, and a hot water supply pipe 7 is provided with an outlet side thermistor 10 for detecting the hot water discharge temperature. (Not shown).

A burner 1 is disposed below the heat exchanger 2, and gas as a fuel is supplied to the burner 1 from a gas pipe 12, while the combustion fan 3 below the burner 1 is rotated. Air is supplied to the burner 1, and the combustion heat generated by the combustion of gas and air in the burner 1 heats the water passing through the heat exchanger 2. In addition, a gas proportional valve 13 that controls the gas supply amount by the valve opening amount and a gas solenoid valve 18 that opens and closes the pipeline are provided in the gas pipe 12.

This type of water heater is provided with a control device 11, and a remote control (not shown) is connected to this control device. The remote control has a button for setting the hot water temperature and a set temperature display section. Is provided. The controller 11 controls the hot water supply operation of the water heater, and when the hot water tap is opened, the flow rate sensor 9 detects the flow rate of water, and when the flow rate exceeds a certain flow rate, the flow rate sensor 9 The control device rotates the combustion fan 3 in response to the signal from the gas solenoid valve 18
Open and change the opening amount of the gas proportional valve 13 to change the heat exchanger 2
It controls the stabilization of the temperature of the hot water discharged from the hot water.

Further, in this water heater, a CO sensor 19 for detecting the CO concentration in the exhaust gas is arranged on the exhaust side.
It is a water heater with an O sensor, the CO sensor 19 is connected to the CO safety device 5 formed in the control device 11, and C
When the O detected concentration reaches the reference concentration, the alarm device 40 is operated, or the gas solenoid valve 18 is closed to stop combustion.
It is configured for safe operation.

In the present embodiment, in the water heater with a CO sensor having the above-mentioned structure, soot clogging is detected by utilizing the decrease in thermal efficiency during combustion operation of the burner due to soot clogging of the heat exchanger 2.

FIG. 1 shows a block diagram of a soot clogging detection section 17 for carrying out the soot clogging detection method of this embodiment. The soot clogging detection unit 17, which is formed inside the control device 11, a temperature detection unit 20, a fuel supply amount measurement unit 21,
A flow rate detection unit 22, a thermal efficiency calculation unit 24, a stability determination unit 25,
An average thermal efficiency calculation unit 27, a comparison determination unit 28, an informing unit 29,
The data storage unit 30 and the memory 31 are provided.

The data storage unit 30 stores the reference thermal efficiency and the allowable deviation. The reference thermal efficiency is the thermal efficiency during burner combustion operation when there is no soot clogging in the heat exchanger 2,
This thermal efficiency gradually rises and stabilizes at a constant value after the start of combustion, as shown by the curve A in FIG. 3. Therefore, the thermal efficiency at this stable time is obtained in advance by experiments, calculations, etc. and stored. There is. Generally, the standard thermal efficiency of the water heaters of Nos. 3 to 16 is about 79 to 83%.

The permissible deviation is a permissible range based on the reference thermal efficiency for determining that the heat exchanger 2 is not clogged with soot. When the heat exchanger 2 has soot clogging, its thermal efficiency is lower than the reference thermal efficiency value when the heat exchanger 2 does not have soot clogging, as shown by a curve B in FIG. Then, when the thermal efficiency value is lower than the reference thermal efficiency value by more than the allowable deviation, the soot clogging detection signal of the combustion device is output.

The reference concentration when the CO safety device 5 performs the CO safety operation is C when the soot clogging detection signal is output.
A value sufficiently lower than the O detection concentration is set. That is, the CO detection concentration reaches the reference concentration before the soot clogging detection signal of the combustion device is output, when the thermal efficiency during burner combustion operation falls below the reference thermal efficiency by more than the allowable deviation, and C
It is configured to perform CO safe operation by the O sensor.

The temperature detector 20 detects the temperature information of the water on the inlet side and the outlet side of the heat exchanger 2 by means of the inlet side thermistor 8 and the outlet side thermistor 10, and regards these as the inlet side temperature and the outlet side temperature. It is added to the thermal efficiency calculation unit 24.

The fuel supply amount measuring unit 21 measures the fuel supply amount supplied to the burner 1, and this fuel supply amount is
It is obtained by measuring the valve opening drive current flowing through the gas proportional valve 13 and added to the thermal efficiency calculation unit 24.

The flow rate detector 23 receives the signal from the flow rate sensor 9 and detects the flow rate of water flowing into the water supply pipe 6,
This detected flow rate is added to the thermal efficiency calculation unit 24.

In the thermal efficiency calculation unit 24, the above-mentioned inlet temperature,
The thermal efficiency during combustion operation of the burner 1 is sequentially calculated and monitored from the information on the outlet side temperature, the fuel supply amount, and the flow rate by using a built-in calculation circuit. The value of thermal efficiency is thermal efficiency = effective heat amount / supply heat amount = λ · (outlet temperature − inlet temperature) · flow rate / (α
-Fuel supply amount) is calculated. Here, λ is the specific heat of the heating medium and is 1 in the case of water.
Further, α is the amount of heat per unit volume of gas that is fuel. The calculated value of the thermal efficiency thus obtained is stored in the memory 31
Are sequentially stored in.

The stability judgment unit 25 reads the calculated value of the thermal efficiency stored in the memory 31, compares the immediately preceding thermal efficiency value with the latest calculated value of the thermal efficiency, and this difference is given in advance. When it becomes smaller than the range, it is judged that the thermal efficiency is stable, and the stability signal is sent to the average thermal efficiency calculation unit 27.
Add to.

When the average thermal efficiency calculation unit 27 receives the stability signal, it reads out the three latest and previous thermal efficiency calculation values stored in the memory 31 after the stability signal is issued, in sequence, The average of the three calculated values of thermal efficiency is calculated by the built-in arithmetic circuit, and this is added to the comparison and determination unit 28 as the average thermal efficiency.

A comparison circuit is formed in the comparison / decision unit 28, which receives the value of the average thermal efficiency and uses this value as the data storage unit 30.
It is compared with the reference thermal efficiency value stored in. And
The value of the average thermal efficiency is higher than that of the reference thermal efficiency.
When it falls below the allowable deviation stored in the table, it is determined that soot clogging has occurred in the heat exchanger 2, a soot clogging detection signal is added to the notifying unit 29, and the CO sensor
When the O-safe operation is not performed, the CO sensor failure detection signal is also added to the notification unit 29.

The notification unit 29 receives the soot clogging detection signal or the CO sensor failure detection signal and sounds the alarm 40 or displays it on the display unit of the remote controller to notify of the soot clogging of the combustion device or the CO sensor failure. I do. In addition, gas solenoid valve
Perform safety operation by closing 18 and stopping combustion.

According to the present embodiment, the thermal efficiency of the burner during combustion operation is sequentially monitored, and when the calculated thermal efficiency value falls below the reference thermal efficiency value by more than the allowable deviation, soot is blocked in the combustion device. The soot clogging detection signal is output when it is determined that the soot clogging is detected, and thus the soot clogging is automatically detected without depending on the human sense.

Even if soot clogging is detected as described above, if the CO safety operation by the CO sensor is not performed, a failure of the CO sensor is detected.

FIG. 4 shows the configuration of a second embodiment in which the present invention is applied to an FF type oil fan heater in which the heating medium is air. A filter 16 is provided on the inlet side of the cold air coming from the room, and the cool air is blown by a fan 15
Is sent to the heat exchanger 2 by the rotation. The inlet side thermistor 8 measures the temperature of the cold air on the inlet side of the heat exchanger 2,
Further, the outlet thermistor 10 detects the temperature of warm air on the outlet side of the heat exchanger 2. The amount of oil supplied to the burner 1 is controlled by an electromagnetic pump 14, which has the same function as the gas proportional valve 13 of the water heater.

Further, the air supplied to the burner 1 is taken in from the outside by the rotation of the combustion fan 3. The combustion heat generated by the combustion of air and oil in the burner 1 heats the air passing through the heat exchanger 2 and discharges the warm air into the room. Further, the exhaust side is equipped with a CO sensor 19 for detecting the CO concentration in the exhaust gas,
A CO safety device 34 is connected to the CO sensor 19 as in the first embodiment, and the CO safety device 34 is configured to perform a CO safety operation when the detected CO concentration exceeds a reference concentration. ing.

Also in the case of this FF type oil fan heater with a CO sensor, if there is soot clogging in the heat exchanger 2, the burner 1
The soot clogging can be detected by sequentially monitoring the thermal efficiency during the combustion operation in the same manner as in the first embodiment. However, in this case, in the fuel supply amount measuring unit 21 in the first embodiment shown in FIG. 1, the electromagnetic pump 14 is used instead of the gas proportional valve 13, and the fuel supply amount of oil is measured by the drive current thereof. In addition, in the flow rate detection unit 22, the flow rate sensor 9
The blower fan 15 is used instead of, and the amount of blown air as the flow rate of air is obtained from this power consumption. This amount of blown air can be obtained by the number of rotations of the blower fan 15, but if this is done, if the filter 16 is clogged or there is backwind from the outlet side of the heat exchanger 2, the exhaust resistance becomes large. The amount of blown air and the number of revolutions of the blower fan 15 are not proportional to each other, and an accurate amount of blown air cannot be obtained from the number of revolutions of the blower fan 15.

On the other hand, when the exhaust resistance increases as described above, the pressure on the blow-out side of the blower fan 15 increases, the blower fan 15 becomes nearly idle, and the load on the monitor 15a that drives the blower fan 15 decreases. The power consumption of the blower fan 15 is small. Also, as the exhaust resistance increases, the air flow also decreases.
Although the power consumption of 15 also tends to be small, since the power consumption and the air flow rate are not necessarily in a proportional relationship, in the present embodiment, the air flow rate is accurately obtained from the information of the rotation speed of the air blower fan 15 and the power consumption. There is.

As described above, the amount of air blown from the number of revolutions of the blower fan 15 and the power consumption, the temperature information of the inlet side and the outlet side of the heat exchanger 2 from the inlet side thermistor 8 and the outlet side thermistor 10, and
The fuel supply amount is obtained by the drive current of the electromagnetic pump 14,
As in the first embodiment, the thermal efficiency is sequentially calculated and monitored based on this information, and the average value of the thermal efficiencies after the stabilization is compared with the reference thermal efficiency, so that the soot clogging is automatically detected. . Further, even if soot clogging is detected, if the CO safety operation by the CO sensor is not performed, a failure of the CO sensor is detected, and the same effect as in the first embodiment is obtained.

The present invention is not limited to the above-mentioned embodiment, and various embodiments can be adopted. For example, in each of the above-described embodiments, when the soot clogging detection signal is generated, and when C
When each allowable deviation when detecting a failure of the O sensor is set to the same value, and the value of stable thermal efficiency is lower than the value of the reference thermal efficiency by more than the allowable deviation, soot clogging is detected, Although it is configured to detect the CO sensor failure,
The detection of the CO sensor failure is faster than the detection of the soot clogging, that is, a value smaller than the allowable deviation is newly set as the quasi-permissible deviation, and the average thermal efficiency value is lower than the reference thermal efficiency value. When it falls below the deviation, CO
A sensor failure may be detected.

In each of the above-mentioned embodiments, the average thermal efficiency value after the thermal efficiency is stabilized is the latest one stored in the memory 31, the previous one, the previous one, and the previous one stored in the memory 31.
The average value of the three thermal efficiencies is used, but the average value of the plurality of thermal efficiencies other than three may be used. Furthermore, the average thermal efficiency may not be calculated, and only the latest thermal efficiency value stored in the memory 31 after the thermal efficiency becomes stable may be used for comparison with the reference thermal efficiency value.

Further, in the above embodiment, the fuel supply amount was obtained from the drive current flowing through the gas proportional valve 13 and the electromagnetic pump 14. However, a flow meter is installed in a gas supply pipe such as a gas pipe or a petroleum pipe. Then, the fuel supply amount may be directly measured.

Further, in each of the above embodiments, the water heater with the CO sensor and the petroleum fan heater are used for explanation.
Even in a combustion apparatus not equipped with a sensor, it is natural that the soot clogging of the combustion apparatus can be detected by the same method as in the above-described embodiments.

Further, in the first embodiment, when the soot clogging detection signal or the CO sensor failure detection signal is applied to the notification section 29, the notification section 29 closes the gas solenoid valve 18 to shut off the gas fuel passage and burn. Although the stop is performed, in the notification unit 29, when each of the detection signals is added, a cutoff signal is added to the CO safety device 5 to cut off the gas fuel path through the CO safety device 5 in the same manner as described above. Alternatively, the combustion may be stopped. In addition, it gives an alarm, turns on a ventilation fan,
It may be displayed on a remote controller or the like.

Further, in the above embodiment, it was determined that the thermal efficiency was stable when the difference between the latest calculated thermal efficiency value and the immediately preceding value was smaller than the allowable range.
It is also possible to set a certain time from when the burner is ignited and to judge that the thermal efficiency is stable when this time has elapsed.

Further, in the above embodiment, after the calculated value of the thermal efficiency is stable, the calculated value of the thermal efficiency is compared with the reference thermal efficiency to detect the soot clogging or the failure of the CO sensor. Is the calculated value of the thermal efficiency stable? It is not determined whether or not, for example, data of the reference thermal efficiency based on the time from the start of ignition of the burner and the amount of combustion is given in advance, and the thermal efficiency calculation value from the time of ignition is compared with this reference thermal efficiency. It is also possible to detect clogging or a CO sensor failure. In this case, since the measured temperature of the output side thermistor 10 causes a time lag depending on the flow rate, the temperature can be accurately obtained by performing correction according to the flow rate.

Further, the combustion fan 3 is used depending on the fuel supply amount.
In a combustion device of a type in which combustion control is performed by varying the air supply amount of the fan so that the fuel supply amount is equal to the fan air supply amount, the fan air supply amount data may be used as the fuel supply amount data. The amount of air supplied may be treated as the amount of fan air blown by the number of fan rotations.

[0045]

Industrial Applicability According to the present invention, the soot clogging of the combustion device is determined by the temperature information of the heating medium on the inlet side and the outlet side of the heat exchanger during the burner combustion operation, the flow rate of the heating medium, and the fuel supply amount. Based on this, the thermal efficiency is sequentially monitored, and when the calculated value of this thermal efficiency falls below the reference thermal efficiency value by more than the allowable deviation, it is judged that there is soot clogging, and the soot clogging detection signal is output. Therefore, it becomes possible to automatically detect the soot clogging of the combustion device without relying on the human sense as in the conventional case.

Further, in the combustion device with a CO sensor,
As described above, even if it is determined that the soot clogging is detected, when the CO safety operation by the CO sensor is not performed, the failure of the CO sensor is automatically detected, and the measures against the CO gas are considered to be perfect. Become.

[Brief description of drawings]

FIG. 1 is a block diagram of a first embodiment for carrying out a soot clogging detection method for a combustion apparatus according to the present invention and a CO sensor failure detection method for a combustion apparatus with a CO sensor using the method.

FIG. 2 is a system configuration diagram of a water heater used in the embodiment.

FIG. 3 is a graph showing changes with time in thermal efficiency with and without soot clogging in the example.

FIG. 4 is a configuration diagram of a second embodiment in which the present invention is applied to an FF type oil fan heater.

FIG. 5 is an explanatory view showing a mode of soot clogging of a water heater of a type in which a combustion fan is arranged on the exhaust side.

FIG. 6 is an explanatory view showing a mode of soot clogging of a water heater of a type in which a combustion fan is arranged on the air supply side.

[Explanation of symbols]

 1 burner 2 heat exchanger 3 combustion fan

Claims (2)

[Claims] 1. A soot clogging detection method for a combustion device, in which fuel supplied to a burner is burned by using air taken in by rotation of a combustion fan, and a heating medium passing through a heat exchanger is heated by the combustion power. And, the temperature information of the heating medium on the inlet side and the outlet side of the heat exchanger, the fuel supply amount,
The information including the flow rate of the heating medium is taken in, the thermal efficiency is sequentially calculated and monitored during the burner combustion operation, and it is compared with the reference thermal efficiency value given in advance, and the calculated thermal efficiency value has a predetermined allowable deviation from the reference thermal efficiency value. A soot clogging detection method for a combustion device, which judges that the soot clogging of the heat exchanger has occurred when the temperature falls below the limit and outputs a soot clogging detection signal. 2. A CO sensor for detecting a CO concentration in exhaust gas in a combustion apparatus, and a C sensor for performing a CO safe operation when the detected CO concentration of the CO sensor reaches a predetermined reference concentration.
An O safety device is provided and outputs a CO sensor failure detection signal when the calculated value of the thermal efficiency calculated by the method according to claim 1 is lower than a predetermined reference thermal efficiency value by a predetermined allowable deviation. Method for detecting failure of CO sensor in combustion apparatus with CO sensor.