JP3123277B2 - Combustion equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion apparatus for reducing the NOx of a burner and ensuring the safety of equipment.

[0002]

2. Description of the Related Art As shown in FIG. 5, a conventional combustion apparatus of this type is provided with a first air-fuel mixture chamber 3 in a burner main body 2 in which a first flame opening 1 is formed. On both sides, a second mixture chamber 6 in which a second flame port 5 is formed by the wall plate 4 is provided.
The first air-fuel mixture chamber 3 and the second air-fuel mixture chamber 6 communicate with each other through an air-fuel mixture communication port 7 provided in the burner main body 2. 8 is a flame holding plate for stabilizing the base of the flame. The wall plate 4 has an air intake 9 for setting the primary air ratio of the second mixture chamber 6. A large number of such burner bodies 2 are housed inside the burner case 10 with the wall plate 4 in contact with each other. Further, a flame detector 11 composed of a frame rod is provided downstream of the first flame opening 1. Reference numeral 12 denotes a nozzle for ejecting gas toward the first mixture chamber 3, and reference numeral 13 denotes a fan for sending air to the first mixture chamber 3 and the second mixture chamber 6.

In the combustion apparatus having the above-described structure, the gas and air ejected from the nozzle 12 are mixed in the first mixture chamber 3 to form an air-fuel mixture, which is ejected from the first flame port 1 and ignited. A stable rich flame having a low oxygen concentration is formed in one flame opening 1. Further, a large amount of air flowing from the air intake port 9 and the air-fuel mixture supplied from the air-fuel mixture communication port 7 are mixed in the second air-fuel mixture chamber 6 to become a lean air-fuel mixture.
And burns under the thermal effect of the rich flame formed in the first flame opening 1 to form a lean flame having a high oxygen concentration.
As described above, in the rich flame combustion, the NOx is reduced as a whole by the amount of the lean flame having a low NOx concentration.

[0004]

However, in the above-described conventional combustion apparatus, if the excess air ratio deviates from a predetermined set source for some reason, as shown in FIG. The amount of air is increased or decreased so that the ion current of the flame detector 11 having the following relationship is equal to the set value, or the amount of gas is increased or decreased to return the excess air ratio to the set value, thereby maintaining a good combustion state. However, the ion current detected by the flame detector 11 is larger when the excess air ratio is closer to 1;
Moreover, the change due to the excess air ratio is large. Therefore, when the excess air ratio is controlled to be large, the ion current has a small change with respect to the excess air ratio, so that there is a problem that the excess air ratio control using the ion current has a large error.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to improve the accuracy of excess air ratio control based on the output of a flame detector.

[0006]

In order to achieve the above-mentioned object, a first object of the present invention is to provide a burner body having a first flame port and a second flame port. An injection plate provided between each of them, a lean communication port provided in the burner body facing the lean mixing chamber surrounded by the injection plate and the burner body, and a lean mixing chamber upstream of the lean communication port. And a flame detector installed downstream of the second flame opening near the air suppression means.

Next, a second means for solving the problem is to provide a flame detector having an opening ratio smaller than the second flame port formed in at least one of the spray plates, and to be installed near the downstream side of the flame detector. And a flame detecting communication port having an opening ratio larger than that of the lean communication port provided on the side surface of the burner main body on the upstream side of the flame detecting section.

Further, a third means for solving the problem comprises a flame detector installed near the downstream side of the first flame port, and an air port for blowing air toward the flame detector.

[0009]

According to the present invention, the amount of air ejected from the second opening near the air suppression means is smaller than the amount of air ejected from the other second opening. Therefore, the lean flame formed in the second flame port near the air suppression means and surrounding the flame detector has a smaller excess air ratio than the lean flame formed in the other second flame ports. As a result, the output of the flame detector greatly changes with respect to the excess air ratio, and the accuracy of the excess air ratio control is improved.

Next, the amount of air ejected from the flame detector is smaller than the amount of air ejected from the second flame port. On the other hand, the amount of the premixed gas ejected from the flame detecting communication port is not much different from the amount of the premixed gas ejected from the lean communication port. Therefore,
The lean flame formed in the flame detecting section and surrounding the flame detector has a smaller excess air ratio than the lean flame formed in the second flame opening. As a result, the output of the flame detector greatly changes with respect to the excess air ratio, and the accuracy of the excess air ratio control can be improved. In particular, the premixed gas ejected from the flame detector has a higher ejection speed than the premixed gas ejected from the second flame port. Therefore, even if the excess air ratio becomes very small for some reason, the temperature of the flame detector rises too much because the lean flame formed in the flame detector keeps the flame relatively far from the flame detector. No thermal deformation occurs.

[0011] Further, since the air ejected from the air port is supplied to the periphery of the flame detector, the rich flame formed on the upstream side of the flame detector is diluted with a relatively low excess air ratio by the supplied air. Transfer to flame. As a result, since the flame detector is wrapped in the lean flame, the output of the flame detector greatly changes with respect to the excess air ratio, and the accuracy of the excess air ratio control is improved. Therefore, even if the mounting position of the flame detector is offset to the side of the second flame port, the flame detector is wrapped in a similar excess air-lean flame,
The output of the flame detector is stable.

[0012]

An embodiment of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1 and FIG. 2, reference numeral 14 denotes a first flame port having a large number of outlets and in which a rich flame is generated. The first flame port is provided on the upper surface of an elongated burner main body 15. Reference numeral 16 denotes a second flame port formed by a large number of gas outlets, where a lean flame is generated, and is provided on a gas ejection plate 17 formed by bending a flat plate into a mountain shape. The ejection plate 17 is provided between each of the plurality of burner bodies 15 arranged side by side. On the side surface of the burner main body 15 facing the lean mixing chamber 18 surrounded by the burner main body 15 and the injection plate 17, a plurality of lean communication ports 19 are provided in the longitudinal direction. In one lean mixing chamber 18, a flat plate-shaped air suppressing means 20 is provided with the lean communication port 1.
9 and is provided upstream. This air suppression means 20
A flame detector 21 composed of a frame rod is disposed in the vicinity of the second flame opening 16 near the above. 22 is provided inside the burner main body 15, and the first flame port 14 and the throat section 23 are provided.
It is a Noren communication port that communicates with. Numeral 24 denotes a nozzle for injecting gas toward the throat portion 23 of each burner body 15, and numeral 25 denotes a lean mixing chamber 1 attached to a burner case 26.
8 and a fan for sending air to the throat portion 23.

Next, the combustion operation in the above configuration will be described. The air supplied from the fan 25 is distributed to the lean mixing chamber 18 and the throat portion 23. On the other hand, the fuel ejected from the nozzle 24 to the throat 23 mixes with the air inside the burner main body 15. The air-fuel mixture inside the burner body 15 is set to an air ratio of 30% to 60%. Part of this air-fuel mixture is blown out from the first flame port 14 through the dense communication port 22 to form a rich flame. On the other hand, most of the remaining air-fuel mixture flows into the lean mixing chamber 18 from the lean communication port 19 and is further mixed with air. The mixture in the lean mixing chamber 18 is 170
% To an air ratio of 250%. The lean air-fuel mixture blows out from the second flame opening 16 to the rich flame, and burns under the thermal influence of the rich flame to form a lean flame having a high oxygen concentration. As described above, in the rich flame combustion, the NOx is reduced as a whole by the amount of the lean flame having a low NOx concentration.

On the other hand, a part of the air supplied from the fan 25 to the lean mixing chamber 18 collides with the air suppressing means 20, so that the air blown out from the second flame opening 16 near the air suppressing means 20 is the other air. The amount is smaller than that of the air ejected from the second flame opening 16. As a result, the lean flame formed in the second flame opening 16 near the air suppression means 20 and surrounding the flame detector 21 has a smaller excess air ratio than the lean flame formed in the second flame opening 16. . Therefore, as shown in FIG. 6, the output of the flame detector 21 greatly changes with respect to the excess air ratio, and the accuracy of the excess air ratio control is improved.

The same effect can be obtained with the flame detector 21 composed of a thermocouple, and in particular, there is a feature that the output change due to the amount of combustion is small, and there is no influence from dust and humidity.

Next, another embodiment will be described with reference to FIG. In FIG. 3, the difference from the above-described embodiment is that at least one of the injection plates 27 has a flame detector 29 having an opening ratio smaller than that of the second flame port 28 and the flame detector 29.
Detector 30 consisting of a frame rod installed near the downstream side of the flame, and a burner main body 31 upstream of the flame detection unit 29
And a flame detecting communication port 33 having an opening ratio larger than that of the lean communication port 32 provided on the side surface of the fuel cell. The other members are the same as those in the embodiment.

Next, the combustion state will be described. The flame detector 29 has a smaller opening ratio than the second flame port 28, that is, the passage resistance is increased. Therefore, the amount of air ejected from the flame detector 29 is smaller than the amount of air ejected from the second flame port 28. On the other hand, the opening ratio of the flame detecting communication port 33 is set to be larger than that of the lean communication port 32, that is, the flame detecting section 29 offsets the increased passage resistance. Therefore, the amount of the air-fuel mixture ejected from the flame detecting communication port 33 is not much different from the amount of the air-fuel mixture ejected from the lean communication port 32. For this reason, the lean flame formed in the flame detection unit 29 and surrounding the flame ejector 30 has a smaller excess air ratio than the lean flame formed in the second flame outlet 28. As a result, the flame detector 30
Output greatly changes due to excess air ratio,
The accuracy of the excess air ratio control is improved.

In particular, the air-fuel mixture ejected from the flame detector 29 has a higher ejection speed than the air-fuel mixture ejected from the second flame port 28. Therefore, even if the excess air ratio becomes very small due to factors such as strong wind, dust clogging, or abnormal air excess ratio control, the lean flame formed in the flame detection unit 29 is relatively far away from the flame detection unit 29 and flame holding is performed. Therefore, the temperature of the flame detector 29 does not rise so much, and no thermal deformation occurs.

Next, another embodiment will be described. As shown in FIG. 4, the present embodiment is different from the above-described embodiment in that a flame detector 35 composed of a frame rod installed in the vicinity of the downstream side of the first flame outlet 34 and air is blown toward the flame detector 35. That is, the air port 36 is provided in the burner end plate 37. The burner end plate 37 is covered by an air chamber 38. The other members are the same as in the above embodiment.

Next, since the air blown out from the air port 36 is supplied to the periphery of the flame detector 35, the rich flame formed on the upstream side of the flame detector 35 is relatively air-rich due to the supplied air. Shift to lean flame with low rate. As a result, since the flame detector 35 is wrapped in the lean flame, the output of the flame detector 35 greatly changes with respect to the excess air ratio, and the accuracy of the excess air ratio control is improved.

Even if the mounting position of the flame detector 35 is shifted to the side of the second flame opening portion 37, the flame detector 35 is wrapped in a similar lean flame having an excess air ratio. Output is stable.

[0023]

As described above, according to the combustion apparatus of the present invention, the following effects can be obtained. (1) The air suppression means is installed in the lean mixing chamber upstream of the lean communication port, and the flame detector is installed downstream of the secondary flame hole near the air suppression means. The lean flame has a smaller excess air ratio than the lean flame formed in other second flame holes. As a result, the output of the flame detector greatly changes with respect to the excess air ratio, and the accuracy of the excess air ratio control is improved. (2) The flame detection unit is set to have an opening ratio smaller than the second flame hole portion, and the communication port for flame detection provided on the upstream side of the flame detection unit is set to have an opening ratio larger than the lean communication port. The air-fuel mixture ejected from the portion has a higher ejection speed than the air-fuel mixture ejected from the second flame hole. Therefore, even if the excess air ratio becomes very small for some reason, the temperature of the flame detector rises too much because the lean flame formed in the flame detector keeps the flame relatively far from the flame detector. No thermal deformation occurs. (3) A flame detector is installed near the downstream side of the first flame hole,
Since an air port for ejecting air toward the flame detector is provided, a lean flame formed by the air ejected from the air port encloses the flame detector. Accordingly, even if the mounting position of the flame detector is shifted to the side of the second flame hole, the flame detector is wrapped in the same lean flame having an excess air ratio, and the mounting error of the flame detector is small.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing a main part of a combustion apparatus according to an embodiment of the present invention.

FIG. 2 is a partial sectional perspective view showing a main part of the combustion apparatus.

FIG. 3 is a partial sectional perspective view showing a main part of a combustion apparatus according to another embodiment of the present invention.

FIG. 4 is a partial sectional view showing a main part of a combustion apparatus according to still another embodiment of the present invention.

FIG. 5 is a partial cross-sectional view showing a main part of a conventional combustion device.

FIG. 6 is a characteristic diagram of the output of the flame detector.

[Explanation of symbols]

 14, 34 First flame port 15, 31 Burner body 16, 28 Second flame port 17, 27 Injection plate 18 Lean mixing chamber 19, 32 Lean communication port 20 Air suppression plate 21, 30, 35 Flame detector 29 Flame Detector 33 Flame detection communication port 36 Air port

Continuation of the front page (72) Inventor Yoichi Kimura 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-4-371709 (JP, A) JP-A 5-141629 (JP) JP-A-5-322157 (JP, A) JP-A-2-54038 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F23N 5/10-5/14 F23C 11/00 329 F23D 14/08 F23N 5/02

Claims (3)

(57) [Claims] 1. A burner body having a first flame port for producing a rich flame, and a second flame port for producing a lean flame, and a plurality of injection bodies provided between the burner bodies arranged in parallel. A lean mixing chamber surrounded by the plate, the injection plate and the burner main body, a lean communication port facing the lean mixing chamber and provided on a side surface of the burner main body, and the lean mixing chamber provided upstream of the lean communication port. A combustion apparatus comprising: an air suppression unit provided in a mixing chamber; and a flame detector installed near the air suppression unit. 2. A flame detector having at least one injection plate and having an opening ratio smaller than that of the second flame port, a flame detector installed near the flame detector, and a side face of a burner main body. The combustion apparatus according to claim 1, further comprising a flame detection communication port provided with an opening ratio larger than the lean communication port. 3. The combustion apparatus according to claim 1, further comprising a flame detector provided downstream of the first flame port, and an air port for blowing air toward the flame detector.