JPH08233261A - Unburnt gas concentration-detecting device for combustion device - Google Patents

Abstract

PURPOSE: To accurately detect the concentration of an unburnt gas by a method wherein the concentration of an unburnt gas is detected by diluting a combustion exhaust gas with air, and at the same time, the pressure of an internal space of an exhaust gas passage, and the pressure of a storage space where an unburnt gas concentration- detecting means is arranged are equalized. CONSTITUTION: A diffusion-limiting film 27 is provided at a connected location between a storage case 25 where a CO sensor 10 is arranged, and an exhaust flue 8. An opening 28 of a small diameter is formed between the diffusion-limiting film 27 and a detecting part 20 of the CO sensor 10, and a pressure-equalizing passage 29 is provided to be connected to the opening. The CO sensor 10 detects the concentration of CO under a state wherein a combustion exhaust gas (CO) which enters the storage space S1 of the storage case 25 by an extremely small amount without flowing through the diffusion-limiting film 27, is diluted with air which is diffused and fed from the opening 28. The pressure of CO is equalized by a pressure equalizing passage 29 when being diffused and discharged to the outside through the opening 28, and for this reason, the CO concentration in the storage space S1 is maintained at a value which is approx. proportional to the CO concentration in an internal space S2 of the exhaust flue 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an unburned gas concentration detecting device for a combustion device equipped with unburned gas concentration detecting means for detecting the concentration of unburned gas in an exhaust passage through which combustion exhaust gas of a burner flows. Regarding

[0002]

2. Description of the Related Art An unburned gas concentration detecting device for a combustion apparatus having the above structure detects the concentration of unburned gas in combustion exhaust gas, and when the detected unburned gas concentration exceeds a set upper limit value, for example, It is designed to ensure the safety in use by stopping the combustion of the combustor or activating the alarm means. In the apparatus, the unburned gas concentration detection means is arranged at a position facing the exhaust passage, and the combustion exhaust gas flowing in the exhaust passage is configured to flow to the unburned gas concentration detection means.

[0003]

In the above-mentioned combustion apparatus, since ventilation is generally performed to supply combustion air to the burner, the combustion exhaust gas flows at a high speed in the exhaust passage due to this ventilation. The flue gas also flows to the unburned gas concentration detecting means at a high speed.
Further, the temperature of the combustion exhaust gas constantly changes depending on the combustion state of the burner, and the combustion exhaust gas also contains substances harmful to the unburned gas concentration detecting means such as sulfur components.

However, in the above conventional structure, since the combustion exhaust gas flows to the unburned gas concentration detecting means as it is, the following problems occur. That is, the flow velocity of the combustion exhaust gas around the unburned gas concentration detection means is high, and when the flow velocity changes, the heat radiation state in the unburned gas concentration detection means changes,
As a result, the output value may change. Particularly, in the unburned gas concentration detecting means of the type that obtains the output value based on the change in the resistance value, there is a disadvantage that the above-mentioned output value fluctuation becomes large.

Further, since the ambient temperature of the unburned gas concentration detecting means is almost the same as the temperature of the flowing combustion exhaust gas, when the temperature of the combustion exhaust gas changes, the ambient temperature of the unburned gas concentration detecting means also changes. The output value may change due to the change in the ambient temperature.

Further, since the combustion exhaust gas flows to the unburned gas concentration detecting means as it is, there is a disadvantage that the detection performance may be deteriorated due to harmful substances such as sulfur components contained in the combustion exhaust gas. .

Therefore, as a method for eliminating the above disadvantages, for example, free diffusion of combustion exhaust gas is restricted between the internal space of the exhaust passage and the storage space in which the unburned gas concentration detecting means is stored. It is conceivable to provide a diffusion restrictor that allows a minute amount of combustion exhaust gas to pass by diffusion, and to open a part of the storage space to the outside of the device to form an opening that allows gas to flow in and out. However, there is still room for improvement in the improved construction because it has the following disadvantages.

That is, when the exhaust passage is blocked by clogging of dust or the like on the lower side of the exhaust passage in the exhaust gas flow direction with respect to the portion where the unburned gas concentration detecting means is arranged, it is better than the closed portion. In the exhaust passage on the upstream side of the exhaust gas flow direction, the internal pressure becomes higher than the normal combustion state, and since the storage space is maintained at atmospheric pressure, the amount of combustion exhaust gas passing through the diffusion limiting body. May increase and the unburned gas concentration detection means may detect the unburned gas concentration as a value higher than the actual unburned gas concentration. On the other hand, for example, when the intake portion of the burner combustion air is blocked by dust or the like, the pressure in the exhaust passage is Since it will be lower than in normal combustion,
The value detected by the unburned gas concentration detection means may be lower than the actual unburned gas concentration. As described above, the output value of the unburned gas concentration detecting means fluctuates due to the difference in the situation of occurrence of combustion failure due to clogging, etc., and there is a disadvantage that proper detection cannot be performed.

The present invention suppresses output value fluctuations due to changes in the flow rate and temperature of combustion exhaust gas, deterioration of detection capability due to harmful substances, etc. as much as possible, and stable output as much as possible regardless of the difference in the occurrence situation of combustion failure. Therefore, it is an object of the present invention to provide an unburned gas concentration detection device for a combustion device capable of accurately detecting the unburned gas concentration.

[0010]

The features of the first invention are as follows:
An unburned gas concentration detection device for a combustion device, comprising unburned gas concentration detection means for detecting the concentration of unburned gas in an exhaust passage through which combustion exhaust gas of a burner flows, said unburned gas concentration detection means And a storage space that is provided between the storage space in which the exhaust gas is arranged and the internal space of the exhaust passage, limits free diffusion of the combustion exhaust gas, and allows the combustion exhaust gas to pass only a set minute amount, and the storage space. A gas inlet / outlet means capable of discharging the combustion exhaust gas in the storage space to the outside is provided while supplying air into the storage space, and the unburned gas concentration detection means is configured to dilute the combustion exhaust gas with the air. In the state, it is configured to detect the concentration of the unburned gas, and is provided with a pressure equalizing means for equalizing the pressure of the internal space of the exhaust passage and the pressure of the storage space. is there.

The characteristic configuration of the second aspect of the invention specifies a configuration suitable for carrying out the first aspect of the invention, in which ventilation means for ventilating combustion air to the burner is provided, and the pressure equalizing means. The point is that it is constituted by a portion on the side of the ventilation path of the ventilation means that is on the upper side of the burner and a pressure equalizing path that connects them in order to equalize the pressure in each of the storage spaces.

A characteristic structure of the third invention is to specify a structure suitable for carrying out the second invention, wherein the gas inlet / outlet means is connected to the pressure equalizing passage and the storage space.
A diffusion limiting body that limits free diffusion of air and the combustion exhaust gas and allows only a small amount to pass therethrough is provided, and the air is diffused and supplied from the ventilation unit side into the storage space. .

A characteristic configuration of the fourth invention is to specify a configuration suitable for carrying out the first, second or third invention, wherein the unburned gas concentration detecting means is constituted by a catalytic combustion type CO sensor. There is a point.

[0014]

According to the characterizing feature of the first invention, the free space of the combustion exhaust gas flowing in the internal space of the exhaust passage is limited by the diffusion limiting body, and only a small amount of the unburned gas concentration detecting means is accommodated in the accommodating space. Will pass through. At this time, even when the combustion exhaust gas is flowing at a high speed in the exhaust passage, the free diffusion is limited by the diffusion limiting body, so that a very small amount of flow occurs in the storage space with almost no flow. The combustion exhaust gas diffuses and enters.

Then, the combustion exhaust gas is diluted with air in the storage space, and the concentration of the unburned gas in the combustion exhaust gas is detected by the unburned gas concentration detection means at an ambient temperature lower than the temperature of the internal space of the exhaust passage. Will be done.

Since the combustion exhaust gas that has entered the storage space can be discharged to the outside by the gas inlet / outlet means, the combustion exhaust gas does not stay in the storage space, and the unburned gas concentration detection means is installed in the exhaust passage. The unburned gas concentration can be detected in a state substantially proportional to the unburned gas concentration of the combustion exhaust gas.

Moreover, the pressure equalizing means equalizes the pressure in the internal space of the exhaust passage and the pressure in the storage space. Therefore, regardless of the difference in the occurrence situation of combustion failure due to clogging of dust, the diffusion limiting body The amount of combustion exhaust gas that enters the storage space through and the amount in the internal space of the exhaust passage are
The state with a constant correlation is always maintained.

According to the characterizing structure of the second invention, the following function is provided in addition to the function of the characterizing structure of the first invention. A part of the ventilation path by the ventilation means, which is on the upper side of the burner, and the storage space are connected by a pressure equalizing path to equalize the pressure in each. In other words, even if the air intake portion of the ventilation means is blocked due to clogging,
Even if the exhaust passage is blocked due to clogging of dust, etc. on the lower side of the exhaust passage in the exhaust gas flow direction than the location where the unburned gas concentration detection means is arranged, it is above the burner in the ventilation passage. Since the pressure becomes almost the same as that in the exhaust passage, the internal pressure of the storage space is equalized with the internal pressure of the exhaust passage.

According to the characteristic constitution of the third invention, in addition to the operation of the characteristic constitution of the second invention, there is the following operation. A small amount of air is diffused and supplied from the ventilation means side into the storage space through the diffusion restricting body provided at the connection between the pressure equalizing path and the storage space, whereby the combustion exhaust gas is diluted. Moreover, since the internal space of the storage space and the inside of the pressure equalizing passage are equalized in pressure, the combustion exhaust gas passes through the diffusion limiting body and is discharged to the pressure equalizing passage side (outside the storage space) while passing a minute amount. become.

According to the characteristic constitution of the fourth invention, the first and second
Alternatively, the following operation is provided in addition to the operation according to the characteristic configuration of the third invention. The contact combustion CO sensor detects the concentration of CO (carbon monoxide) as unburned gas in the combustion exhaust gas, so it is possible to effectively determine whether or not the CO concentration is a concentration that may adversely affect the human body. be able to.

[0021]

According to the characterizing feature of the first invention, the unburned gas concentration detecting means is less likely to be adversely affected by the change of the output value due to the change of the flow velocity and temperature of the combustion exhaust gas,
The unburned gas concentration in the combustion exhaust gas in the exhaust passage can be detected effectively and accurately.

Moreover, the combustion exhaust gas to the unburned gas concentration detecting means is a minute amount, and the deterioration of the detecting ability due to harmful substances such as sulfur components can be suppressed, and the durability of the unburned gas concentration detecting means is improved. An accurate detection state can be maintained for a long period of time.

Further, in the case where combustion failure of the burner occurs due to clogging of dust or the like, the unburned gas concentration in the storage space is the same as that in the inner space of the exhaust passage regardless of the difference in the defective occurrence situation such as the difference in clogging point. Since it becomes a value corresponding to the unburned gas concentration of, it becomes possible to accurately detect the unburned gas concentration in the exhaust passage based on the unburned gas concentration in the storage space.

According to the characterizing structure of the second invention, the following effects are obtained in addition to the effects of the characterizing structure of the first invention. By effectively utilizing the ventilation structure by the ventilation means, the pressure in the internal space of the exhaust passage and the pressure in the storage space can be adjusted by a simple configuration in which the location on the upper side of the burner and the storage space are connected by a pressure equalizing path. It became possible to equalize.

According to the characterizing feature of the third invention, the following effect is obtained in addition to the effect of the characterizing feature of the second invention. The simple structure equalizes the pressure in the exhaust passage and the pressure in the storage space, while the rational configuration provides the supply of dilution air into the storage space and the outside of the storage space for combustion exhaust gas. It became possible to perform discharge at the same time.

According to the characteristic configuration of the fourth invention, the first and second aspects are provided.
Alternatively, there are the following effects in addition to the effects of the characteristic configuration of the third invention. The CO concentration in the combustion exhaust gas can be accurately detected. For example, when a safety device is provided such as issuing an alarm or stopping combustion when the CO concentration exceeds the set upper limit value, the It is possible to activate the safety device.

[0027]

Embodiments will be described below with reference to the drawings. FIG.
FIG. 1 shows a hot water supply device as an example of a combustion device. This hot water supply device includes a hot water supply unit A, a control unit H that controls the operation of the hot water supply unit A, and a remote control operation unit R that issues various control information to the control unit H.

The hot water supply unit A has a burner 2 inside the combustion chamber 1.
And a heat exchanger 3 heated by the burner 2, and a water inlet 4 for supplying water to the heat exchanger 3 and hot water heated by the heat exchanger 3 are supplied to a hot water tap (not shown). The hot water outlet 5 is connected. An igniter 6 for igniting the burner 2 and a frame rod 7 for detecting an ignition state are provided near the burner 2. Further, a fan 9 is provided as a ventilation unit that ventilates the combustion air to the burner 2 and discharges the combustion exhaust gas of the burner 2 to the outside through the exhaust pipe 8 forming the exhaust passage L.

A catalytic combustion type CO sensor 10 for measuring the concentration of CO (carbon monoxide) as unburned gas contained in the combustion exhaust gas of the burner 2 is provided near the exhaust pipe 8.

The fuel supply passage 11 for supplying the fuel gas to the burner 2 is provided with an electromagnetically operated on-off valve 12 and an electromagnetically operated gas proportional valve 13 capable of changing and adjusting the fuel supply amount. 4, a water flow sensor 14 for detecting the amount of water flow is provided, and a hot water discharge sensor 5 for detecting the hot water temperature after being heated by the heat exchanger 3 is provided in the hot water discharge passage 5.

The remote control operating unit R is provided with an operation switch 16 for turning on / off the operation state of the hot water supply unit A, a hot water supply temperature setting switch 17 for setting a target hot water supply temperature, an operation lamp 18 showing the operation state, and a combustion state of the burner 2. Showing a combustion lamp 19
Etc. are provided.

The control unit H detects the incomplete combustion discriminating means 100 for discriminating whether or not the output value of the CO sensor 10 exceeds the set value in the steady combustion state of the burner 2 and the detection of the water flow rate sensor 14 in the operating state. When the value exceeds the set amount, the burner 2 is ignited and the value detected by the hot water temperature sensor (hot water temperature)
So that the target hot water supply temperature is reached, the fuel supply amount by the gas proportional valve and the ventilation amount by the fan 9 are controlled, and the combustion of the burner 2 is stopped when the incomplete combustion determination means 100 determines incomplete combustion. The combustion control means 101 is provided.

Next, the structure of the CO sensor 10 will be described. In the detection unit 20 of the CO sensor 10, as shown in FIG. 2, the sensor element 21, the temperature compensating reference element 22, and the two resistance elements 23 and 24 are connected in a bridge circuit state, and The DC power supply E is supplied between the connection between the resistance element 23 and the connection between the temperature compensation reference element 22 and the resistance element 24. Each of the sensor element 21 and the temperature compensating reference element 22 is composed of a platinum wire carrying a catalyst, and is heated to about 200 degrees by the flow of an electric current, and the unburned gas contacting with the surface catalyses the catalyst. It is designed to burn. At this time, since the catalyst carried on the sensor element 21 has selectivity for CO, a difference occurs in the element temperature between the sensor element 21 and the temperature compensating reference element 22. Since the resistance value of the platinum wire changes depending on the temperature, the difference between the resistance values of the sensor element 21 and the temperature compensation reference element 22 increases as the CO concentration in the combustion exhaust gas increases. Therefore, the output value Vs according to the CO concentration in the combustion exhaust gas is the sensor element 2 in the bridge circuit.
1 and the reference element 22 for temperature compensation, and the connection portions of the resistance elements 23 and 24.

Then, the detection unit 20 of the CO sensor 10
1 is a stainless steel storage case 25, as shown in FIG.
In the storage space S1 formed by
The exhaust pipe is provided so as to be attached to the exhaust case 8, and an opening is formed in the storage case 25 on a side opposite to the pedestal 26 in a state of being largely opened, so that the opening faces the internal space S2 of the exhaust pipe 8. It is connected and attached to the opening formed in 8.

A diffusion limiting film 27 as a diffusion limiting body that limits free diffusion of the combustion exhaust gas and allows only a small amount of the combustion exhaust gas to pass through at the connection between the storage case 25 and the exhaust pipe 8.
Is provided. The diffusion limiting film 27 is made of, for example, a Teflon fiber film, a carbon fiber non-woven fabric, or the like, and is configured to allow only a small amount to pass while blocking the free flow of combustion exhaust gas. Therefore, even when the flow rate of the combustion exhaust gas in the exhaust stack 8 is high,
The combustion exhaust gas that enters the storage space S1 passes by diffusion with almost no gas flow.

A pressure equalizing means P for equalizing the pressure in the internal space S2 of the exhaust passage L and the pressure in the storage space S1 is provided. To be more specific, the storage case 2
In FIG. 5, a small-diameter opening 28 is formed at an intermediate position between the diffusion limiting film 27 and the detection unit 20, and at a position between the burner 2 and the fan 9 and near the air blowing portion of the fan 9. Inside the ventilation path at the location and the opening 2
A pressure equalizing passage 29 serving as a pressure equalizing means P is provided in a state where the pressure equalizing means P and 8 are connected. Then, at the connection point between the pressure equalizing path 29 and the storage space S1 in the storage case 25, the same structure as the diffusion limiting film 27 is provided, and the free diffusion of air and the combustion exhaust gas is limited, and only a minute amount. A diffusion limiting film 30 is provided as a diffusion limiting body that allows passage.

The diffusion limiting film 30 is constructed so as to limit the free diffusion of not only combustion exhaust gas but also air so that only a minute amount is allowed to pass. Therefore, the wind generated by the fan 9 does not flow into the storage space S1 through the pressure equalizing passage 29, and the internal pressures at the respective locations to which the pressure equalizing passage 29 is connected are simply equalized. Become.
Moreover, since the diffusion limiting film 30 can allow air and combustion exhaust gas to pass therethrough by a slight amount by diffusion, the combustion exhaust gas that enters from the exhaust passage L side can flow through the pressure equalizing passage 2
It is configured to be diluted by the air supplied by diffusion from 9 and to be discharged by diffusion to the pressure equalizing passage 29 side.

As a result, the CO sensor 10 detects the CO concentration in a state where the combustion exhaust gas that has entered the storage space S1 in a non-flowing state is diluted with the air diffused and supplied through the opening 28. Is configured. At this time, the combustion exhaust gas is approximately 1/5 to 1/1 in the air.
It is diluted to about 0.

Since the CO sensor 10 is constructed as described above, in the detecting portion 20, the amount of combustion exhaust gas that is extremely smaller than the amount of combustion exhaust gas in the exhaust passage is almost non-flowing, and The CO concentration can be detected in a state where the sensor atmosphere temperature is small (temperature close to the outside air temperature) regardless of the temperature change of the combustion exhaust gas diluted with air in the exhaust passage.

Further, though the combustion exhaust gas always enters the storage space S1 by diffusion through the diffusion limiting film 27,
The combustion exhaust gas can be diffused to the outside through the opening 28, and the pressure is equalized by the pressure equalizing passage 29, so that the CO concentration in the storage space S1 is the exhaust stack 8.
It can be maintained as a value that is almost proportional to the CO concentration in the internal space S2.

Therefore, adverse effects due to the flow velocity and temperature of the atmospheric gas and deterioration of the detection performance due to harmful components in the combustion exhaust gas such as sulfur components are prevented as much as possible, and the occurrence of defects such as differences in clogging points is prevented. The CO concentration in the combustion exhaust gas can be accurately detected regardless of the difference.

The set value for the incomplete combustion determination by the incomplete combustion determination means 100 corresponds to the upper limit value of the CO concentration in the exhaust passage L set in advance in the storage space S.
The CO concentration within 1 (concentration lower than the upper limit value) is set.

[Other Embodiments] (1) In the above embodiment, as the pressure equalizing means P, the internal space of the ventilation path at a location near the air blowing portion of the fan 9 is connected to the opening 28. Although the case where the pressure equalizing path 29 is provided is illustrated, the pressure equalizing path 29 may be configured as follows. As shown in FIG. 4, the connection path 3 is provided in the storage space S1.
6 is provided with a pressure adjuster 37 capable of changing and adjusting the internal pressure of the storage space S1 and a pressure sensor 38 for detecting the pressure of the internal space S2 of the exhaust passage L.
And a pressure sensor 39 for detecting the internal pressure of the storage space S1.
And the control unit H controls the pressure sensors 3
Pressure regulator 37 so that the detection values of 8 and 39 are the same.
May be adjusted and controlled.

(2) In the above embodiment, the diffusion limiting body is made of a fiber membrane, a non-woven fabric or the like.
The diffusion limiting body may be a stack of stainless steel nets having a large number of minute passage holes, and the like, in short, it has heat resistance to withstand the high temperature of combustion exhaust gas, It is possible to maintain a state in which a small amount of combustion exhaust gas is diffused, with the conditions that it does not chemically change with respect to the components contained in and that specific components are not adsorbed (that is, the gas passage holes are not blocked). As long as it is a material, its material, shape, etc. are not limited. Further, among the components contained in the combustion exhaust gas, a specific component other than CO (for example, steam) may not pass through.

(3) In the above embodiment, the burner combustion is stopped when the CO concentration exceeds the set value (incomplete combustion is determined). However, instead of such a configuration,
The configuration may be such that the ventilation amount of the fan is corrected to the increasing side and combustion of the burner is continued while avoiding incomplete combustion.

(4) In the above embodiment, the case of the catalytic combustion type CO sensor is exemplified as the unburned gas concentration detecting means.
A semiconductor type CO sensor may be used, or an oxygen (O ₂ ) sensor, a carbon dioxide (CO ₂ ) sensor, a hydrogen (H ₂ ) sensor, or the like may be used.

(5) In the above embodiment, the hot water supply device is illustrated as the combustion device, but the present invention is not limited to the hot water supply device but can be applied to other combustion devices such as a fan heater.

It should be noted that reference numerals are added to the claims to facilitate the comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a layout diagram of a CO sensor.

FIG. 2 is a circuit diagram of a CO sensor detection unit.

FIG. 3 is a schematic configuration diagram of a hot water supply device.

FIG. 4 is a schematic configuration diagram showing a pressure equalizing means of another embodiment.

[Explanation of symbols]

 2 heat exchanger 9 ventilation means 10 unburned gas concentration detection means 27 diffusion limiting body 29 pressure equalizing path S1 storage space S2 internal space L exhaust path P pressure equalizing means

Claims (4)

[Claims] 1. An unburned gas for a combustion apparatus, comprising unburned gas concentration detection means (10) for detecting the concentration of unburned gas in an exhaust passage (L) through which combustion exhaust gas of a burner (2) flows. A concentration detecting device, wherein the storage space (S1) in which the unburned gas concentration detecting means (10) is arranged and the internal space (S) of the exhaust passage (L).
2) and a diffusion limiting body (27) which is provided between the storage space (S1) and a diffusion limiting body (27) which limits free diffusion of the combustion exhaust gas and allows the combustion exhaust gas to pass only a set minute amount. And a gas inlet / outlet means capable of discharging the combustion exhaust gas in the storage space (S1) to the outside, and the unburned gas concentration detection means (10) is a state in which the combustion exhaust gas is diluted with the air. Is configured to detect the concentration of the unburned gas, and the pressure in the internal space (S2) of the exhaust passage (L),
An unburned gas concentration detector for a combustion device, comprising a pressure equalizing means (P) for equalizing the pressure in the storage space (S1). 2. Ventilation means (9) for ventilating combustion air to said burner (2) is provided, and said pressure equalizing means (P) is said burner in the ventilation path of said ventilation means (9). The unburned combustion apparatus according to claim 1, wherein the uncombusted portion of the combustion device is constituted by a pressure equalizing path (29) that connects them to equalize the pressure in each of the storage space (S1) and the portion on the side better than (2). Gas concentration detector. 3. The diffusion means for restricting free diffusion of air and the combustion exhaust gas, and allowing only a minute amount to pass through at a connection point between the pressure equalizing path (29) and the storage space (S1). A restriction body (30) is provided, and from the side of the ventilation unit (9) into the storage space (S1),
The unburned gas concentration detection device for a combustion device according to claim 2, wherein the air is diffused and supplied. 4. The unburned gas concentration detection device for a combustion device according to claim 1, 2 or 3, wherein the unburned gas concentration detection means (10) is composed of a catalytic combustion type CO sensor.