JP2001304542A - Equipment for prevention of incomplete combustion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce variations in a combustion shutoff level for prevention of incomplete combustion, prevent an incorrect determination of incomplete combustion at initial time of ignition, and reduce costs of manufacturing. SOLUTION: A sensor burner 20 of a Bunsen combustion type is provided with a burner plate 24 in which a main flame port 24a formed in the center of a disk and a flame stabilization port 24b provided on the periphery of the ports 24a are opened. The burner 20 is further provided with a cylindrical body 22 surrounding the periphery of the burner plate 24, and a burner body 21 forming a fuel-gas flow path. A thermopile TC is inserted from the outside into the wall surface of a cylindrical body 22. A main flame of the main flame port 24a is stabilized by a flame-stabilization port 24b and the cylindrical body 22, even in an incomplete combustion time of the sensor burner 20, the electromotive force of the thermopile TC is gently decreased. Thus, an incomplete combustion can be stably detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for preventing incomplete combustion, which is incorporated in a combustor such as a forced-combustion gas water heater that forcibly takes in combustion air and burns it, and detects incomplete combustion.

[0002]

2. Description of the Related Art Conventionally, a combustor has been provided with a safety device for preventing carbon monoxide poisoning by detecting indoor oxygen deficiency due to leakage of exhaust gas or incomplete combustion caused by a defective supply / exhaust system of the combustor. ing. Such a safety device is disclosed in Japanese Patent Application Laid-Open No. 9-42658. As shown in FIGS. 6 and 7, a mixing pipe 5 in which fuel gas and combustion air are mixed by suction, and the mixing pipe 5 mixes the fuel gas and the combustion air. A burner plate A made of ceramics, in which a large number of flame outlets from which the air-fuel mixture is ejected are arranged concentrically with different diameters and open, constitutes an all-primary pneumatic burner. A cylindrical guard 7 that prevents the secondary air for combustion from coming into contact with the flame formed on A is installed. This burner is provided with a gas nozzle 9 in the vicinity of the opening 8 of the mixing tube 5 and sucks air required for combustion into the mixing tube 5,
Basically, all primary air combustion that does not require secondary air for combustion is performed.

The inside of the cylindrical guard 7 is provided with a thermocouple TC.
(Flame detection element)
An electromagnetic valve (not shown) provided in the gas flow path of the main burner of the water heater is controlled to open and close according to the electromotive force V of C. In other words, the sensor burner 6 is provided to detect a situation in which the flame state changes before the main burner in response to the supply failure of the combustion air.
Is detected based on the electromotive force V of the thermocouple TC, thereby preventing incomplete combustion of the main burner.

[0004] In the incomplete combustion preventing device configured as described above, all primary air combustion is performed, and a flame is formed near the burner plate A (solid line in FIG. 6). From this state, if the supplied oxygen is insufficient due to a decrease in the air ratio due to a decrease in the air flow and the combustion state deteriorates, the combustion speed of the fuel gas becomes slower than the ejection speed, and the fuel gas cannot be balanced on the burner plate A. A flame is formed at the opening at the tip of the cylindrical guard 7 (broken line in FIG. 6). As described above, since the flame is greatly lifted and the thermocouple TC is surrounded by the low-temperature unburned gas, the electromotive force V is, as shown in FIG.
It drops rapidly.

[0005] By catching such a rapid change in the electromotive force V due to the change in the flame formation position, the solenoid valve is closed to cut off the supply of the fuel gas before the main burner of the water heater causes incomplete combustion. Stop burning. That is, as shown in FIG. 8, a determination reference value Vs for stopping combustion is set, and when the detected electromotive force V falls below the determination reference value Vs, combustion is stopped to prevent incomplete combustion. In particular, since the electromotive force V sharply decreases due to the lift of the flame and greatly falls below the determination reference value Vs, it is easy to detect incomplete combustion, and a reliable operation can be obtained. Note that the supply oxygen deficiency level I corresponding to the determination reference value Vs is set to the stop level Is.

[0006]

However, although the technique of capturing such a rapid change in electromotive force is advantageous in that it is less susceptible to disturbances or the like, it stops combustion in response to incomplete combustion of the main burner. There is a disadvantage that it is difficult to adjust the stop level Is of the sensor burner 6.
That is, since the stop level Is changes depending on the air ratio, it easily shifts due to variations in the product such as the gas nozzle diameter and the air damper diameter. Therefore, the adjustment of the determination reference value Vs does not correct the shift of the stop level Is. Therefore, in order to stop the combustion when the supply oxygen deficiency level I at which the incomplete combustion of the main burner occurs occurs, it is necessary to individually adjust the nozzle diameter and the damper diameter.

Further, since the sensor burner 6 is an all-primary pneumatic burner, it is necessary to use ceramics having heat resistance. This will be described. In the all-primary-air burner, the combustion is started inside the burner plate A and the combustion is completed on the surface without requiring the secondary air for combustion, so that the unburned gas region is not formed and the surface temperature is high. . Therefore, the durability of the burner plate A is improved by using heat-resistant ceramics.

However, the burner plate A made of ceramics is disadvantageous in that it is very expensive, brittle and easily broken. Moreover, due to the poor formability of the material, the position of the flame port and the diameter of the flame port of the burner plate A are likely to shift, and the positional relationship with the thermocouple TC varies from product to product. In some cases, it did not reach the criterion value Vs, and a sufficient electromotive force was not obtained. Therefore, the incomplete combustion prevention device of the present invention solves the above-mentioned problems, suppresses variation in the stop level for preventing incomplete combustion, reduces the manufacturing cost, and makes an erroneous determination of incomplete combustion at the initial stage of ignition. The purpose is to prevent it.

[0009]

According to a first aspect of the present invention, there is provided an apparatus for preventing incomplete combustion according to the present invention, which is disposed in an air supply passage of a main burner for forcibly taking in combustion air and burning. An incomplete combustion prevention device for preventing incomplete combustion of the main burner based on the flame state of the sensor burner, wherein the sensor burner forms a main flame opening at the center, and the main flame opening is formed around the main flame opening. A flame-portion-forming portion formed with a flame-holding flame portion for holding the main flame of the cylinder, and surrounding the flame-portion forming portion, the base of the main flame has a cylindrical body that prevents contact with surrounding combustion air. The gist of the present invention includes a Bunsen burner and a flame detecting element that is disposed at a predetermined distance from the flame opening forming portion in the cylinder and outputs a detection signal according to the temperature of the main flame.

A second aspect of the present invention provides a device for preventing incomplete combustion according to the first aspect of the present invention, wherein a metal is used for a material of the flame port forming portion. .

In the incomplete combustion preventing device according to the first aspect of the present invention having the above-described structure, the flame holding flame is provided around the main flame flame. The flame is held, and the cylinder prevents the induced secondary air for combustion from coming into contact with the flame of the main flame opening and the flame holding flame opening, preventing the main flame from being blown off by this secondary air. As a result, the flame holding property of the main flame becomes good. Therefore, when the supply oxygen is insufficient, the base of the main flame is held without being lifted and the unburned gas region of the main flame expands with a decrease in the burning speed while the combustion speed is reduced. Moreover, since the air ratio is originally less than 1 in Bunsen combustion, the temperature of the main flame itself decreases with a decrease in the air ratio, so that the detection signal output from the flame detection element is, for example, as shown by a solid line in FIG. It changes slowly with a shortage of oxygen supply. Further, since the cylinder surrounds the flame port forming portion having the main flame port portion and the flame detecting element to prevent mixing of secondary air for combustion between the base of the main flame and the flame detecting element, The detection element is not affected by the temperature rise due to the combustion of the unburned gas, and can accurately detect a change in the air ratio due to blockage or the like. In this manner, the sensor burner detects a decrease in the air ratio due to a blockage of the supply / exhaust system or the like, thereby preventing incomplete combustion of the main burner.

Further, in the incomplete combustion preventing apparatus according to the second aspect of the present invention, since the sensor burner performs Bunsen combustion requiring secondary air for combustion, the unburned gas region is formed on the surface of the flame port forming portion. Are formed, and the surface temperature is lower than that of the all-primary-air burner. Therefore, even if a metal having lower heat resistance than ceramics is used as the material of the flame port forming portion, the durability is good.
Therefore, the metal flame port forming portion is less expensive than the ceramic flame forming portion and is less likely to be damaged. Furthermore, since the dimensional accuracy of the position of each flame port and the size of the flame diameter is good, the positional relationship with the flame detecting element is hard to vary from product to product. Judgment can be prevented.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to further clarify the structure and operation of the present invention described above, a preferred embodiment of the incomplete combustion preventing device of the present invention will be described below. FIG. 5 is an explanatory diagram of a combustion section of a forced-combustion gas water heater provided with an incomplete combustion prevention device as viewed from above. This water heater has a combustion chamber 5
A plurality of flat main burners 51 are arranged in parallel inside the cylinder 0, and a damper 5 for adjusting primary air is provided at the end of the throat 52.
3 is provided, and a gas nozzle 5 provided on the nozzle base 54 is provided.
5 supplies the fuel gas. The gas flow path provided in the nozzle table 54 is provided with a proportional control valve for adjusting the performance (amount of combustion) and an electromagnetic valve for opening and closing the gas flow path. A blower fan (not shown) is provided below the combustion chamber 50, forcibly supplies combustion air to the combustion chamber 50, performs Bunsen combustion with the main burner 51, and heats the heat exchanger with the combustion heat. It is configured to tap.

FIG. 1 shows a sensor burner 20 juxtaposed to a main burner 51. Two flat plates are formed with depressions by press molding, and the outer periphery is caulked and joined to form a fuel gas flow path. This is a Bunsen combustion type burner provided with a burner body 21 to be formed, a burner plate 24 formed of a disc-shaped punching metal having a large number of flame openings, and a thermocouple TC. As shown in FIG. 3, the burner plate 24 has a main flame port 24a formed in the center thereof divided into a plurality of openings, and has an outer periphery at a predetermined distance from the main flame port 24a. A flame holding flame opening 24b composed of a plurality of aligned openings is formed.

As shown in FIG. 1, the burner body 21 has a mixing pipe portion 26 into which the fuel gas and the combustion air are sucked and mixed, and a burner plate 24 through which the air-fuel mixture of the mixing pipe portion 26 is ejected. And a semi-cylindrical cylindrical body 22 surrounding the periphery of the burner plate 24, and a thermocouple TC provided in the cylindrical body 22 for supporting the thermocouple TC in a concave shape. A thermocouple support 27 is formed.

In the cylindrical body 22, the thermosensitive tip 10 of the thermocouple TC is inserted from the outside of the wall surface of the cylindrical body 22, and is provided in parallel with the burner plate 24 at a predetermined distance from the surface of the burner plate 24. . The thermocouple TC is connected to a combustion controller of the water heater, and is configured to control opening and closing of an electromagnetic valve provided in a gas flow path of the main burner 51 of the water heater in accordance with an electromotive force V of the thermocouple TC. Accordingly, the sensor burner 20 and a controller that controls opening and closing of the solenoid valve based on the output of the thermocouple TC constitute an incomplete combustion device.

In the sensor burner 20, the burner plate 24 and the thermocouple TC are inserted between the two burner bodies 21 into the plate support 25 and the thermocouple support 27, and then the outer periphery of the burner body 21 is caulked. The gas nozzle 30 faces the opening 28 of the mixing tube 26, and the primary air for combustion is also sucked in by the blower fan. However, since the sensor burner 20 is of the Bunsen combustion type, an air amount smaller than the theoretical air amount is supplied to the opening 28 of the mixing pipe section 26 as primary air for combustion.

In the incomplete combustion prevention device having the above-described structure, a flame is formed by transferring the fire from the main burner 51 of the water heater to the main flame opening 24a and the flame holding flame opening 24b of the sensor burner 20 by an ignition operation. In the Bunsen combustion type sensor burner 20, the tip of the main flame of the main flame port 24a extends in a normal state (at the time of complete combustion) in which sufficient oxygen is supplied, and the surrounding air is discharged from the tip of the cylindrical body 22. Bunsen burns as the next air. And the base of the main flame is flame holding flame mouth 2
The flame is held by the sleeve fire of 4b.

In addition, the main flame is not lifted because the secondary air for combustion is prevented from entering the flame holding flame opening 24b by providing the cylindrical body 22. Thus, the flame holding flame opening 24b and the cylinder 2
2 improves the flame holding property of the main flame.

Next, a description will be given of combustion stop control when the supply of oxygen to the sensor burner 20 becomes insufficient due to a decrease in the oxygen concentration in the room or a blockage of the exhaust portion of the water heater. When the air supply / exhaust system is blocked and the air volume decreases, the air ratio of the air-fuel mixture decreases because the amount of air for combustion decreases. On the other hand, when the oxygen concentration in the room decreases, the air volume (air ratio ), The amount of oxygen contributing to combustion decreases, and in any case, the supplied oxygen decreases. Since the sensor burner 20 is provided in parallel with the main burner 51, the oxygen supply state of the sensor burner 20 also changes according to the oxygen supply state of the main burner 51.

As shown in FIG. 2, even if the supplied oxygen decreases, the base of the main flame is not lifted but held in the sensor burner 20 by the flame holding effect of the flame holding port 24b. In addition, since the main flame extends above the cylinder 22 due to the decrease in the burning speed, the low-temperature unburned gas increases around the flame detecting element. Further, the temperature of the main flame itself decreases as the air-fuel ratio decreases. As a result, as shown in FIG. 4, the electromotive force V output from the thermocouple TC decreases gradually as the amount of supplied oxygen becomes insufficient.

Based on the gently changing electromotive force characteristic, a reference value Vs corresponding to the stop level Is at which the supply oxygen shortage level I for stopping the combustion is set in advance, and the electromotive force V falls below the value Vs. Then, control is performed to stop the combustion, thereby preventing incomplete combustion of the main burner 51. For this reason, even when the electromotive force of the sensor burner 20 during normal combustion varies between products, it can be easily dealt with simply by adjusting the setting of the electromotive force value called the determination reference value Vs. That is, it is possible to obtain the sensor burner 20 in which the stop level Is hardly varies for each type of gas such as city gas or propane gas or for each product.

Here, a conventional example will be described for comparison. In the conventional example, in order to utilize the rapid output characteristic of the electromotive force V depending on whether the flame formation position is at the flame outlet or at the tip of the cylindrical guard 7, the determination reference value Vs is set as shown in FIG. Even if it is changed, the corresponding stop level Is does not change. Therefore, if the stop level Is shifts,
Even if the determination reference value Vs is adjusted, the stop level Is does not change. Therefore, since it is not always possible to stop the combustion when the supply oxygen deficiency level I reaches the desired level I, the air amount and gas amount of the sensor burner must be adjusted, and it takes time to change the nozzle diameter and the damper opening. There was a problem that it took. On the other hand, in the present embodiment, the output of the thermocouple TC changes gradually with the change of the length of the main flame and the temperature of the main flame in accordance with the state of supply of oxygen to the main flame. The stop level Is can be adjusted by adjusting the value Vs. Therefore, the incomplete combustion of the sensor burner 20 can be properly determined, and the incomplete combustion of the main burner 51 can be prevented beforehand, and the safety of the user can be ensured.

In the case where the flame holding flame opening 24b is not provided in the burner plate 24, or in the case where the secondary air is fed into the cylinder 22, the main burner 51 is completely burned due to poor flame holding properties. Even when the engine is lifted, the lift may occur, the electromotive force cannot be obtained, and it is determined that the combustion is incomplete. In the configuration in which the secondary air is fed into the cylinder 22, unburned gas is burned by the secondary air. In some cases, an electromotive force is obtained and incomplete combustion of the main burner 51 cannot be detected. However, in the present embodiment, such an inconvenience does not occur due to the interaction between the flame holding flame formed by the flame holding flame opening 24b and the cylindrical body 22.

The sensor burner 20 includes a cylindrical body 22 and a burner plate 24 having a main flame port 24a.
In order to prevent secondary air from entering between the base of the main flame and the thermocouple TC around C, it is less susceptible to disturbances such as headwinds. In this way, the thermocouple TC can properly detect a decrease in the air ratio of the air-fuel mixture due to a blockage of the supply / exhaust system.

Further, since the sensor burner 20 is formed by caulking two press-formed burner bodies 21, the manufacturing is easy and the manufacturing cost is very low. In addition, since the sensor burner 20 performs Bunsen combustion, it is not necessary to use a conventional ceramic burner plate as the burner plate 24, and it is possible to use an inexpensive pressed product (punching metal) that is hardly damaged. Furthermore, since the flame port of the burner plate 24, which is a pressed product, is formed with a higher dimensional accuracy than the ceramic-made one, the positional accuracy with the thermocouple TC is good. As a result, the electromotive force characteristics are less likely to vary, and incomplete combustion can be accurately prevented.

The fuel gas is a hydrogen-based gas (city gas).
In the case of using, it is easy to flash back because of the high burning speed, but since the main flame opening 24a is formed by dividing into a plurality of small openings, flashback is prevented by the quenching action and the burner plate Combustion continues at the top of 24. The main flame outlet 2
4a, one large flame opening may be opened in the center of the burner plate 24, and a plurality of small openings may be formed by laying a wire net on the large flame opening. In addition, when methane-based gas (natural gas) having a slow burning rate is used, there is no risk of flashback, so there is no need to divide the main flame opening portion 24a into a plurality of openings. It can be formed.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments at all, and it is needless to say that the present invention can be carried out in various modes without departing from the gist of the present invention. It is. For example, a flame rod that detects a flame current may be used instead of the thermocouple TC as the flame detection element. Also, sensor burner 2
Instead of using the two burner bodies 21, the mixing tube 26 may be made up of a pipe and the remaining part may be made up of two press plates, or the burner plate 24.
May be manufactured by die casting.

Alternatively, an electromotive force value V (ie, Vi-.DELTA.V) which is lower by a predetermined value .DELTA.V from the stable initial electromotive force Vi at the start of combustion may be set as the determination reference value Vs. Further, each product may detect the amount of decrease in electromotive force V per hour (differential value), and may perform control to stop combustion when the amount of decrease per hour falls below a predetermined value. As a result, when the combustion state rapidly deteriorates, the combustion can be stopped before the electromotive force V reaches the determination reference value Vs, and the incomplete combustion can be quickly prevented.

[0030]

As described in detail above, claim 1 of the present invention
According to the incomplete combustion prevention device described, while preventing the base flame of the main flame from being lifted by the flame holding flame opening and the cylindrical body, the main flame extends according to the oxygen supply state, and the temperature of the main flame itself decreases. Therefore, the temperature of the main flame in the vicinity of the flame detecting element gradually decreases as the supply of oxygen becomes insufficient, and the reference value for preventing incomplete combustion can be easily adjusted.

Further, according to the incomplete combustion prevention device of the present invention, since the sensor burner performs Bunsen combustion, the durability is good even when a metal material is used for the flame port forming portion, and the ceramic burner is made of ceramic. It is cheaper and less susceptible to damage. In addition, the metal flame port forming part has good dimensional accuracy such as the position of each flame port and the flame diameter, and the positional relationship with the flame detecting element is hard to vary from product to product. Can be prevented.

[Brief description of the drawings]

FIG. 1 is a side sectional view of an incomplete combustion prevention device according to an embodiment.

FIG. 2 is a cross-sectional view of the incomplete combustion prevention device according to the embodiment as viewed from a side.

FIG. 3 is a top view of the incomplete combustion prevention device according to the embodiment.

FIG. 4 is an output characteristic diagram of the incomplete combustion prevention device according to the embodiment.

FIG. 5 is an explanatory view of a combustion section of a forced combustion gas water heater provided with the incomplete combustion prevention device according to the embodiment as viewed from above.

FIG. 6 is a cross-sectional view of a conventional incomplete combustion prevention device as viewed from a side.

FIG. 7 is a top view of a conventional incomplete combustion prevention device.

FIG. 8 is an output characteristic diagram of the conventional incomplete combustion prevention device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Tip heat sensitive part, 20 ... Sensor burner, 21 ... Burner body, 22 ... Cylindrical body, 24 ... Burner plate, 24a
... Main flame outlet, 24b ... Flame holding flame outlet, 26 ... Mixing tube, 3
0: gas nozzle, TC: thermocouple.

Claims (2)

[Claims] An incomplete combustion prevention for preventing incomplete combustion of a main burner based on a flame state of a sensor burner disposed in an air supply passage of a main burner forcibly taking in combustion air and burning. In the apparatus, the sensor burner has a main flame opening at a center thereof, and a flame opening forming part having a flame holding flame for holding the main flame of the main flame at the periphery thereof. Surrounding the mouth forming portion, at the base of the main flame, a Bunsen burner having a cylinder that prevents contact with the surrounding combustion air, and arranged at a predetermined distance from the flame forming portion in the cylinder, An incomplete combustion prevention device comprising: a flame detection element that outputs a detection signal according to the temperature of the main flame. 2. The incomplete combustion preventing device according to claim 1, wherein a metal is used as a material of the flame port forming portion.