JPH074640A - Burner - Google Patents

Abstract

PURPOSE:To accurately and easily detect an air ratio of combustion of a burner by providing a temperature detector for detecting the ratio in a secondary air passage between a flame out of a flame generating area of the burner and the flame. CONSTITUTION:The air fed out of a hot water supplying apparatus combustion of a burner by providing a temperature detector for the rest as secondary air between burner bodies 10, and eventually discharged out of the apparatus from an exhaust cylinder together with burned exhaust gas. The bodies 10 are so disposed that the flames 13 of the adjacent bodies 10 are not brought into contact with each other even if sizes of the flames 13 are varied and a sufficient interval is provided to obtain a secondary air passage. Thus, a gap is formed between the flames 13 and 13, and a thermocouple 14 is so disposed in the gap as not to be brought into contact with the flame 13. Accordingly, the thermocouple 14 is decided at its temperature in balance of radiation heat from the flames 13 with cooling of the flow of the secondary air, thereby generating a thermoelectromotive force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion device, and more particularly to a burner combustion air ratio detection technique by a gas combustion device.

[0002]

2. Description of the Related Art Conventionally, so-called Bunsen type burners have been used in various combustion equipments because of their wide combustion range, low noise, easy combustion control, and the like. Further, a so-called rich-burn combustion burner, which has a flame port that alternately ejects a rich mixture and a lean mixture of a fuel gas and combustion air and burns both at the same time, produces a larger amount of nitrogen oxides than the former. Since it is small (hereinafter referred to as low NOx), it is used even though the good combustion range is narrow. In recent years, especially low NOx
Since it has become necessary to improve performance such as noise reduction and noise reduction, the effective combustion range becomes narrower, and the air ratio (the ratio of the actually used air amount to the theoretical air amount) is accordingly reduced.
It has become necessary to control and burn. Note that controlling the air ratio means correcting the air ratio to an optimum value because the air ratio deviates from the set air ratio for various reasons. As a technique for detecting the air ratio, a method of providing a flame temperature detecting element such as a thermocouple in the flame of the burner and detecting the air ratio from the output of the flame temperature detecting element is a practical method.
Known at 435. This technique utilizes the characteristic of the temperature change of the flame with respect to the change of the air ratio.

[0003]

However, in the above technique, when the size of the flame changes due to the increase or decrease of the input (fuel gas amount), the temperature change captured by the thermocouple is large, and its characteristic is that of the air. It cannot be said that it corresponds to the change in the ratio. Hereinafter, the reason will be described by taking a Bunsen type burner as an example. The Bunsen type burner is shown in FIG.
As shown in (a), the burner main body 8 serves as a passage for the fuel gas.
The nozzle 86 is faced to 0, the fuel gas ejected from the nozzle 86 is sucked, the primary air is taken in by the kinetic energy at the time of the ejection, and the air-fuel mixture is ejected from the flame port 82. At the same time, the flame 83 generated in the upper portion of the flame port 82 simultaneously takes in and combusts secondary air from its surroundings by diffusion. Therefore, the flame 83 is composed of a high-temperature outer flame HO that is fully supplied with secondary air and is completely burned, and a low-temperature inner flame H that is in the interior of the flame 83 and that is incompletely burned only by the primary air.
I and.

In the prior art, in order to detect the air ratio, a flame temperature detecting element 84 (for example, a thermocouple, a thermistor or the like, which will be simply referred to as a detecting element 84 hereinafter) is installed in the outer flame HO. When the detection element 84 is in the region of the external flame HO, as the air ratio increases as described above,
The output of the detection element 84 gradually decreases. (Fig. 11
However, if the input (fuel gas amount) and the primary air ratio (ratio of the primary air amount to the total amount of the primary air amount and the secondary air amount) in the Bunsen type burner change, FIG.
As shown in (a), the shape of the flame 88 changes and the internal flame GI
Is applied to the detection element 84 and the output characteristics are affected. Therefore, in such a case, the output of the detection element 84 when the air ratio is increased is small because the temperature of the internal flame GI is initially detected, and the internal flame GI is reduced as the air ratio increases. Then, the temperature of the external flame GO is detected. That is, the output characteristic of the detection element 84 once increases and then decreases as shown in FIG. Therefore, if the characteristics change under such conditions, there is a problem in that it is not accurate to detect the air ratio from the output of the detection element 84. Further, in the combustion of propane gas, natural gas, etc., the temperature of the flame is as high as 1300 to 1600 degrees Celsius, which causes a problem in the heat resistance of the detection element 84 and limits the usable detection elements. There was also. An object of the combustion apparatus of the present invention is to solve the above problems and detect the air ratio in burner combustion accurately and easily.

[0005]

In order to solve the above-mentioned problems, a first combustion apparatus of the present invention has a burner provided with a flame port for inhaling a fuel gas and primary air and ejecting a mixture of the fuel gas and the primary air. In a combustion device that is installed side by side in such a manner that secondary air flows between the burners, a temperature detecting element for detecting an air ratio in the secondary air passage between the flame outside the flame generation region of the burner and the flame. The main point is to set up. The second combustion device is provided with a plurality of rich-side flame ports to which a rich air-fuel mixture of fuel gas and combustion air is introduced, and a light-air mixture having a higher air ratio than the rich-air mixture provided adjacent to the rich-side flame ports. A plurality of light-side flame ports to which the air-fuel mixture is guided are alternately provided, and in a combustion device that injects and burns each air-fuel mixture from the rich-side flame port and the light-side flame port,
The gist is that a temperature detecting element for detecting the air ratio is provided in the light air-fuel mixture ejection passage between the flame of the dark side flame port and the flame.

[0006]

In the combustion apparatus of the present invention having the above structure, a temperature detecting element is installed in the middle of the secondary air passage between the flame in the first invention, and in the second invention between the rich flame and the rich flame. Since the temperature detecting element is installed in the middle of the light air-fuel mixture passage, the output of the temperature detecting element is unlikely to be affected by the size of the flame or the like. Therefore, when the combustion air ratio changes, the output of the temperature detection element corresponding to it changes. By utilizing the characteristic, the air ratio of the combustion air can be accurately and easily detected by the output of the temperature detecting element.

[0007]

EXAMPLES In order to further clarify the constitution and operation of the present invention described above, preferred examples of the combustion apparatus of the present invention will be described below. FIG. 1 is a schematic configuration diagram of a combustion apparatus as a first embodiment, and FIG. 2 is an example in which so-called J-type Bunsen burners are used and incorporated into a water heater. This combustion apparatus is provided with a plurality of Bunsen burners 15 provided at intervals with a flame port 11 for ejecting a mixture of primary air sucked at the same time as fuel gas supplied from a nozzle 24, and between them. The secondary air flows toward the top. In this embodiment, the heat exchanger 21 is provided at the upper part of the Bunsen burner 15 and the fan 22 at the lower part thereof is provided.
The structure is such that combustion air is supplied by the burner, and part of the air flowing from the outside of the water heater is the burner body 10.
Is sucked as primary air into the interior of the burner, and the rest is burner body 1
This is because it flows as secondary air between 0 and is finally discharged from the exhaust pipe 23 to the outside of the water heater together with the burned exhaust gas. The adjacent burner bodies 10 have flames 13
Even if the size of the flame changes, the flames 13 do not come into contact with each other and are arranged with a sufficient distance so that the secondary air passage is secured, so a gap is generated between the flames 13 and The thermocouple 14 is installed in the gap so as not to contact the flame 13. Therefore, the thermocouple 14 generates a thermoelectromotive force whose temperature is determined by the balance between the radiant heat from the flame 13 and the cooling by the flow of secondary air. In addition, thermocouple 1
Since 4 does not come into contact with the flame 13 and is cooled by the flow of secondary air, it does not become hot unlike the case of the prior art, and various types of detection elements can be used.

Looking at the temperature change of the flame 13 with respect to the air ratio, for example, as shown in FIG. 3A, the temperature gradually decreases as the air ratio increases. (Here, the normal combustion state is assumed, and the case where the air ratio is 1.0 or more is described.) This is because the flame 13 is equal to or more than the required air amount.
This is because the air does not contribute to the increase in the heat generation of combustion when the air is taken in, and conversely, the flame 13 is cooled by the air and the temperature density decreases. Therefore, looking at the change in the radiant heat amount of the flame 13 with respect to the air ratio, the radiant heat amount corresponds to the temperature of the flame 13 so that the air ratio increases, for example, as shown in FIG. In the same manner as above, it gradually decreases. Further, the change of the secondary air amount with respect to the air ratio is directly proportional to the increase of the air ratio as shown in FIG. 4A, and the cooling action of the thermocouple 14 due to the flow of the secondary air is almost directly proportional to the air ratio. To respond. As a result, the temperature of the thermocouple 14 with respect to the air ratio has an effect of both the amount of radiant heat and the cooling of the secondary air (see FIG. 3).
From (a) and FIG. 4 (a), for example, as shown in FIG. 4 (a), a characteristic is shown that the air ratio smoothly decreases as the air ratio increases. For the above reason, if the temperature of the thermocouple 14 is measured, the air ratio can be detected accurately and easily.

Next, a combustion apparatus as a second embodiment is shown in FIG.
This will be described using 6. The second embodiment is an example used for so-called rich / lean combustion air ratio detection. In the rich / lean combustion burner of the present embodiment, two thin plates are superposed to form a fuel gas passage, and a primary air intake port 61 is provided in the middle of the passage.
The flame gas outlet 62 is provided at the fuel gas outlet to form one unit, and units of different types are alternately arranged to form the entire unit. By sandwiching the light burner 66, which burns with a light air-fuel mixture, between the rich burners 60, which burn with a rich air-fuel mixture, the rich flame 63 is provided at the flame port 62 of the rich burner 60.
A light flame 68 is formed above the flame outlet 67 of the light burner 66, and the two flames are brought into contact with each other in a well-balanced manner to achieve good combustion. In addition, the light air-fuel mixture is ejected from the upper portion of the flame outlet 67, and no flame is formed between the light flames 68. Of course, there is no formation of the rich flame 63 between the rich flame 63.

In this embodiment, a thermocouple 64 is installed above the flame outlet 67 of the light burner 66, that is, between the rich flame 63 and the rich flame 63. The temperature of the thermocouple 64 is additionally influenced by the lean flame 68 as compared with the case of the first embodiment. Although the thermocouple 64 is cooled by the jet of the light air-fuel mixture, its effect on the air ratio is affected by the amount of secondary air in the first embodiment (see FIG. 4).
It can be considered almost the same as (a)). Therefore, the difference from the previous example is only the radiant heat from the lean flame 68. Looking at the change in the radiant heat applied to the thermocouple 64 of the lean flame 68 with respect to the air ratio, the position of the lean flame 68 moves away from the flame outlet 67 to the upper part as the air ratio increases. Moreover, the radiant heat is reduced. Therefore, if the effect of this radiant heat is added to the temperature change of the thermocouple 14 with respect to the air ratio of the previous example (FIG. 4 (a)), the temperature of the thermocouple 64 will be larger and smoother in the same manner as in the first embodiment. Shows a declining property. The thermocouple 64 does not come into contact with the rich flame 13 and the lean flame 68 and is cooled by the flow of the lean mixture, unlike the case of the prior art. It does not reach a high temperature, and various types of detection elements can be used. For the above reason, also in the case of the present embodiment, if the temperature of the thermocouple 64 is measured, the air ratio can be detected accurately and easily.

Next, a combustion apparatus as a third embodiment is shown in FIG.
Will be explained. The combustion apparatus of the third embodiment has two partition plates 88 parallel to the side surface of the thermocouple (14 or 64) of the combustion apparatus of the first or second embodiment (FIG. 1 or 5) so as to sandwich it. It was installed in. Hereinafter, the configuration of the first embodiment will be described, but the same applies to the case of the second embodiment. The partition plate 88 prevents the flames 13 adjacent to the left and right of the thermocouple 14 from directly contacting the thermocouple 14, and also regulates the flow of secondary air. Therefore, according to this combustion device, even if the pitch (interval) of the burner main body 10 becomes narrow, the air ratio can be accurately and easily detected for the same reason as in the above-described embodiment.

Further, a combustion apparatus as a fourth embodiment is shown in FIG.
Will be explained. The combustor of the fourth embodiment has an opening in the central portion of the lower part of the thermocouple (14 or 64) of the combustor of the first or second embodiment (FIG. 1 or 5), that is, upstream of the secondary air or the lean mixture. A flow rate control plate 99 having a section is installed. Hereinafter, the configuration of the first embodiment will be described, but the same applies to the case of the second embodiment. The flow rate control plate 99 can easily change the flow rate of the secondary air flowing toward the thermocouple 14 by changing the size of the central opening. Therefore, the cooling effect of the thermocouple 14 by the secondary air can be easily adjusted. That is, the thermoelectromotive force of the thermocouple 14 can be arbitrarily set, and it is very convenient in using this combustion device.

As described above, according to the combustion apparatus of this embodiment, the air ratio of the combustion air can be detected by the temperature output of the thermocouple installed between the burner flames. Moreover, since the temperature of the thermocouple itself does not become high, the durability performance of the thermocouple is improved and various detecting elements can be used. Although the embodiments of the present invention have been described above, it is needless to say that the present invention is not limited to these embodiments and can be implemented in various modes. For example, a thermistor or the like can be used as the detection element in addition to the thermocouple.

[0014]

As described above, in the combustion apparatus of the present invention, the air ratio can be accurately and easily detected by the output of the temperature detecting element installed between flames.
This has an excellent effect that the air ratio of the air used for combustion can be controlled to perform optimum combustion.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a combustion apparatus as a first embodiment.

FIG. 2 is a structural diagram in which the first embodiment is incorporated in a water heater.

FIG. 3 is a graph showing the relationship between the air ratio, flame temperature, and radiant heat in the first embodiment.

FIG. 4 is a graph showing the relationship between the air ratio and the secondary air amount in the first embodiment, and the air ratio and the thermocouple temperature in the first and second embodiments.

FIG. 5 is a schematic configuration diagram of a combustion device as a second embodiment.

FIG. 6 is a schematic configuration diagram of a rich / lean combustion burner.

FIG. 7 is a graph showing the relationship between the air ratio and the amount of radiant heat in the second embodiment.

FIG. 8 is a schematic configuration diagram of a combustion device as a third embodiment.

FIG. 9 is a schematic configuration diagram of a combustion device as a fourth embodiment.

FIG. 10 is a schematic configuration diagram of a combustion device as a conventional example.

FIG. 11 is a graph showing a relationship between an air ratio and a detection element output in a conventional example.

[Explanation of symbols]

 10, 60, 66, 80 Burner body 13, 63, 83 Flame 11, 62, 67, 82 Flame port 14, 64, 84 Thermocouple 88 Partition plate 99 Flow control plate

Claims (2)

[Claims] 1. A combustor in which fuel gas and primary air are sucked in, burners provided with flame ports for ejecting a mixture thereof are arranged in parallel at intervals, and secondary air is caused to flow between the burners,
A combustion device characterized in that a temperature detection element for detecting an air ratio is provided in a secondary air passage between the flame outside the flame generation region of the burner. 2. A plurality of rich-side flame ports to which a rich air-fuel mixture of fuel gas and combustion air is introduced, and a light-air mixture provided adjacent to the rich-side flame ports and having a higher air ratio than the rich air-fuel mixture. Is alternately provided with a plurality of light side flame outlets, and in the combustion device that ejects and burns the respective air-fuel mixture from the rich side flame outlet and the light side flame outlet, the flame and flame of the rich side flame outlet A combustion device characterized in that a temperature detection element for detecting an air ratio is provided in the light air-fuel mixture ejection passage between the two.