JPS62255716A - Combustion device - Google Patents

Abstract

PURPOSE:To prevent abnormal combustion such as imperfect combustion, backfire or the like in a main burner by a method wherein the air excessive rate of a total primary combustion burner is detected as the air excessive rate in a pilot burner. CONSTITUTION:A fan 20 supplies combustion air through an air feeding tube 18 while a ventilating tube 27, connected to the air feeding tube, distributes the combustion air. One part of the divided combustion air is mixed with fuel in an evaporating chamber 4 to form premixture while the other part of the combustion air, supplied through the ventilating tube, is mixed in a mixing chamber 10 with the premixture from the evaporating chamber 4 to form the premixture with an air excessive rate of 1.0 or higher. Further, the premixture from the mixing chamber 10 is burnt in a total primary combustion burner head 8 while a part of the premixture, formed in the evaporating chamber 4, is taken out and is burnt by a pilot burner 30. A detecting means, which consists of flame rods, detects the state of combustion of the burner 30. As a result, detection in the range of combustion may be facilitated and imperfect combustion as well as backfire may be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a combustion detection means for a primary combustion burner that mixes and burns fuel and combustion air.

2. Description of the Related Art A conventional combustion apparatus of this type was constructed as shown in FIG. A mixing plate 3, which also serves as a burner head holder, is disposed at the upper opening of the vaporizing cylinder 2 in which the heater 1 is embedded, and a vaporizing chamber 4 is defined inside the vaporizing cylinder 2. Furthermore, a burner head 8 is disposed at the end of the mixing plate 3, and is composed of a rectifier tube 6 with a large number of small holes 5, and a combustion tube 7 made of a mesh provided on the outside thereof. A mixing chamber 1 is formed inside by a burner head 8 and a cap 9 that closes the upper end of the burner head 8.
o is partitioned. Further, on the outside of the combustion tube 7 and the vaporization tube 2, there is provided a glass tube 12 which transmits heat relative to its width and an exhaust tube 14 with an exhaust port 13 fully open, which is separated from the exhaust passage 11. Note that the upper end of the exhaust passage 11 is closed by an exhaust cap 15. On the other hand, an air supply nozzle/116 and a fuel supply nozzle 17 are opened in the side wall of the vaporization cylinder 2, and each nozzle is connected to a fan 20 and a pump 21 via an air supply pipe 18 and a fuel supply pipe 19.
For example, Japanese Patent Application Laid-Open No. 188718/1983). In addition, 2
2 is the oil tank, 23 is the combustion state detection Surflame Rono F
Terror.

During upward revision, when the vaporizer cylinder 2 is heated to a predetermined temperature by the heater 1, the fan 20 supplies smoldering air into the vaporizer chamber 4 via the air supply pipe 18 and the air supply nozzle 16, and the pump 21 supplies fuel from the oil tank 22 to the vaporization chamber 4 via the fuel supply pipe 19 and the fuel supply nozzle 17. Vaporization chamber 4
The fuel that has entered is vaporized on the heated inner wall of the vaporization cylinder and mixed with combustion air to form a premixture with an excess air ratio of 1.0 or more. B) Konai Qi flows into the mixing chamber 10 via the mixing plate 3,
After being mixed evenly here, the mixture is ejected from the small hole 5 of the rectifier tube 6, ignited by an igniter (not shown), and burned on the surface of the combustion tube 7. Since the combustion tube 7 has a relatively large area, the combustion here is a low-load combustion, and the red heat of the combustion tube 7 accompanying combustion is dissipated through the glass tube 12, so the combustion flame temperature is low. , low NOx combustion is performed. The exhaust gas generated by combustion passes through the exhaust passage 11 and is discharged from the exhaust port 13, but at this time, the vaporizer cylinder 2 is heated and heat is recovered.

Problems to be Solved by the Invention However, in the above configuration, the frame rod 2
However, there has been a problem in that combustion detection using No. 3 and air-fuel ratio control using the same are difficult.

Next, the reason will be explained. Characteristics of the flame rod current value when a constant voltage is applied to the flame rod 23 and the excess air ratio of the premixture is changed in the structure shown in Figure 5.
As shown in the figure. As shown in the figure, the flame rod current reaches its maximum at the point where the excess air ratio λ of the mixture is 1.0, that is, the amount of combustion air in the premixture is equal to the theoretical amount of air. Here, since the burner performs all primary combustion in which secondary air is not supplied to the combustion surface, if the excess air ratio λ of the premixture is less than 1.0, incomplete combustion will occur due to lack of air. . Furthermore, the excess air ratio λ of the premixture is 1.0
Even if the temperature is above 1.0, the red heat of the combustion tube 7, that is, the temperature is the highest, so the combustion tube 7 and the fN tube 6
There is a risk of overheating and backfire. Therefore, in the combustion apparatus with the above configuration, the practical range of the excess air ratio λ of the premixture is above point A in FIG. Middle 0~
0' line), combustion is stopped by a control circuit (not shown).

However, if the excess air ratio λ of the mixture is set at point B in the figure, the ionic current 1f becomes IB, but this current value IB also occurs at B′ on the low excess air ratio side. Judgment based on simple current value indicates B on the incomplete combustion side.
Since the excess air ratio of '' cannot be detected, it was necessary to also determine the slope of the current value with respect to the excess air ratio. In addition, it is fine if the current value characteristics of the frame rod do not always change as shown by the solid line in the figure, but if the current value characteristics change as shown by the broken line in the figure due to aging or uneven installation of the frame rod, the air Threshold o-o across the excess rate
', and there was a problem that it was not possible to detect the flashback region or incomplete combustion region. Furthermore, if no voltage is applied due to a failure in the voltage application circuit, etc. to the frame rod, the frame rod current value will of course become zero, but the current value judgment section There was a risk that it would be judged as normal because it was below.

Means and Description for Solving the Problems In order to solve the problems, the combustion device of the present invention has a vaporization chamber to which one side of the combustion air dividedly supplied from the fan is supplied to generate a highly concentrated premixture. , the other air chamber to which combustion air is supplied, and a mixing chamber which receives and mixes the air-fuel mixture and combustion air f from the vaporization chamber and the air chamber to completely produce a mixture with an excess air ratio of 1.0 or more. In addition, a pilot burner that takes out and burns a part of the premixture generated in the vaporization chamber and a flame rod that detects the combustion state of the pilot burner are provided.

Operation The present invention has the above-mentioned structure, and the main burner is a full-order burner. The combustion state t in the ignition burner is detected and controlled by the pilot burner and flame rod that completely burns the highly enriched premixture, making it easy to detect in the combustion range and completely preventing incomplete combustion and flashback.

EXAMPLE Hereinafter, an example of the present invention will be explained using FIGS. 1 and 2. Incidentally, in FIG. 1, the same parts as those in the conventional example shown in FIG. 4 are given the same numbers, and explanations thereof will be omitted. An air chamber 26 partitioned by an air chamber main body 24 and a partition plate 25 is provided between the vaporization chamber 4 and the mixing chamber 10, and the air chamber 26 and the air supply pipe 18 are connected by an air supply pipe 27. There is. Further, a mixture passage 28 from the vaporization chamber 4 to the mixing chamber 10 is arranged through the air chamber 26, and an air ring outlet 29 is opened at the connection part with the mixing electric passage 28 at the upper part of the air chamber 26. are doing. On the other hand, a premixture outlet 31 to the pilot burner 30 protrudes from the mixture passage 28, and a premixture outlet 31 leading to the vaporization chamber 4
It opens diagonally on the side. The electrode of the frame rod 23 faces toward the pilot burner 30.

In the structure described above, the vaporizer cylinder 2 is heated to a predetermined value ff by the heater 1.
, [When heated to [], the hood 20 and pump 21 are activated to supply combustion air and fuel to the vaporization chamber 4. At this time, combustion air is transferred from the air supply pipe 18 to the air chamber 27 via the air supply pipe 27.
Therefore, the excess air ratio λ of the premixture formed in the vaporization chamber 4 by the fuel vaporized in the electrification chamber 4 and the combustion air supplied to the vaporization chamber via the air supply nozzle 16
is set to 1.0 or less. The premixture formed in the vaporization chamber 4 is uniformly mixed while passing through the mixture passage 28 and flows out into the mixing chamber 10, and the combustion air from the air pipe 27 flows into the air chamber 26 and the air outlet. After 29 hours, it flows out into the mixing chamber 10. Vaporization chamber 4 inside mixing chamber 10
The premixture from the air chamber 26 and a part of the combustion air from the air chamber 26 are mixed in the mixing chamber 10, resulting in a relatively lean mixture with an excess air ratio λ of 1.0 or more, and the entire primary combustion burner head It erupts at 8. On the other hand, the mixture from the vaporization chamber 4 that has been homogenized in the mixture passage 28 is transferred to the pilot burner 30 from a premixture outlet 31 that partially protrudes into the mixture passage 28.
The flames of the pilot burner 30 are ignited by an igniter (not shown) and combusted. At this time, the pilot burner 30 burns with a low excess air ratio, so the ionic current obtained by inserting the flame rod 23 into the flame and applying the full voltage is as shown in Figure 2 (5) for the pilot burner alone. It exhibits the characteristics shown in . In FIG. 2 (4), the vertical axis is the ion current value of the flame rod, and the horizontal axis is the excess air ratio λ of the premixture supplied to the pilot burner 3o, that is, the premixture formed in the vaporization chamber 4. Ion current value characteristics? As can be seen from the figure, the excess air ratio λ is 0.8.
The ionic current reaches its maximum value at a change of ~0.9. If this characteristic is plotted on the abscissa with the air excess ratio λ at -na 8, which is the main burner which changes in conjunction with the pilot burner 30, it will become as shown by the solid line in FIG. 2(B). in this case,
The point that flashback does not occur on the low excess air ratio side of the main burner (
If the threshold value of the ion current If is set to satisfy the point (point B in the figure) and the point at which lift misfire does not occur on the high air excess ratio side (point 14 in the figure), then Normal combustion is completely guaranteed within the range of excess air ratio λ (indicated by the arrow in the figure) that indicates the above ion current. That is, even when the excess air ratio λ is 1.0 or less, which was a problem in the conventional example, the ion current of the flame rod becomes less than the threshold value, so abnormal combustion can be detected and combustion can be stopped.

Note that the broken line in Fig. 2 (B) conceptually shows the ionic current characteristics when the flame rod is inserted into the flame of the all-primary combustion burner, which is the main burner, as in the conventional example. .

Further, FIG. 3 shows another embodiment of the present invention.
The difference from the embodiment shown in the figure is that the divided combustion air is directly supplied from the air pipe 27 to the mixing chamber 10 without passing through the air chamber 26. The operation and effects of this embodiment are similar to those shown in FIG.

Effects of the Invention As is clear from the above description, the combustion apparatus of the present invention divides combustion air into two parts: one is a vaporization chamber that forms a rich mixture of combustion air and vaporized fuel, and is sent to a mixing chamber; An air chamber that supplies combustion air to the mixing chamber to form an air-fuel mixture to be combusted in the primary combustion burner head, a pilot burner that takes out and burns the air-fuel mixture formed in the vaporization chamber, and a pilot. With all the detection means for detecting the combustion state of the burner, it is possible to easily detect the excess air ratio of the primary combustion burner, which is the main burner, as the excess air ratio of the pilot burner. Abnormal combustion such as complete combustion, backfire, and lift misfire can be prevented. Furthermore, ignition of all the primary combustion burners can be accomplished extremely easily by first igniting the pilot burner that burns a rich air-fuel mixture, and then igniting the main burner using the flame of the pilot burner.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a combustion device showing a first embodiment of the present invention, and FIGS. 2A and B are characteristic diagrams showing ion current characteristics of a flame rod inserted into the flame of a pilot burner of the same device. FIG. 3 is a longitudinal sectional view of a combustion device showing a second embodiment of the present invention, FIG. 4 is a longitudinal sectional view showing a conventional combustion device of this type, and FIG. 5 is an ion current of a flame rod in a conventional example. FIG. 2... vaporization chamber, 4... vaporization chamber, 8...
...Full combustion burner head, 10... Mixing chamber, 18... Air supply 'fl, 20. River... Fan, 23. Mountain/Frame rod, 26.・・・・・・
Air chamber, 27. River... Air pipe, 28. Old mixture passage, 29.. Air outlet, 30.. Pilot burner. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Illustration owner] Kusuuni + 7 Ruuo V to ji〒11 Snow≦In Figure 3 Figure 4 Figure 5

Claims (4)

[Claims] (1) A fan that supplies combustion air through an air supply pipe, an air supply pipe that is connected to the air supply pipe and branches the combustion air, and one of the divided combustion air is mixed with fuel to form a premixture. A vaporization chamber, a mixing chamber in which a premixture with an air excess ratio of 1.0 or more is formed by the other combustion air supplied via the air pipe and a premixture from the vaporization chamber, and a premixture from the mixing chamber. This combustion device is equipped with an all-primary combustion burner head that burns gas, a pilot burner that extracts and burns a part of the premixture formed in the vaporization chamber, and a detection means that detects the combustion state of the pilot burner. (2) A vaporizing chamber is divided inside a bottomed cylindrical vaporizing cylinder, and an air pipe is connected to the upper part of the vaporizing chamber, and the mixing chamber is connected to an air chamber with an air outlet to the mixing chamber. 2. The combustion device according to claim 1, further comprising an air-fuel mixture passage that passes through the vaporization chamber and guides the pre-air mixture from the vaporization chamber to the mixing chamber. (3) The combustion apparatus according to claim 1, wherein the detection means is a flame rod inserted into the flame of the pilot burner. (4) The excess air ratio of the premixture formed in the vaporization chamber is 1
．． The combustion device according to claim 1, wherein the combustion temperature is 0 or less.