JP2860282B2 - Liquid combustion burner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid combustion burner using a liquid fuel, and more particularly to a means for shortening the flame thereof.

[0002]

FIG. 14 is a sectional view showing an example of a conventional liquid combustion burner.

The burner is provided with a combustion cylinder 2 to which combustion air 4 is supplied from the outside, and is provided near the front end of the combustion cylinder 2 and supplied with a liquid fuel 16 from the outside to atomize it. A nozzle 12 for injecting toward the tip of the combustion tube 2 (ie, downstream); a flame holding plate 6 provided near the nozzle 12 in the combustion tube 2 for stabilizing a flame 18; The combustion air 4 formed between the outer peripheral portion of the combustion tube 2 and the inner wall of the combustion tube 2 and supplied into the combustion tube 2
And an annular air port 10 for jetting from the periphery to the downstream side. The illustration of the ignition device is omitted (the same applies to the embodiments described later).

The combustion cylinder 2 has, for example, a cylindrical shape, and the inside thereof is normally burned through a wind box 3 which acts to stabilize the flow of combustion air 4 as shown in the figure. Supply air 4 is supplied.

The flame stabilizing plate 6 has a function of stabilizing the flame 18 by creating a negative pressure region at the downstream side with the flow velocity of the combustion air 4 and bringing the ignition surface closer to the flame stabilizing plate 6. In this example, it has a disk shape. In this example, a hole 8 through which fuel 16 injected from the nozzle 12 passes is provided at the center thereof. Further, a plurality of small holes 9 or slits for ventilation may be provided in the plate surface of the flame holding plate 6 in order to prevent soot adhesion on the surface of the flame holding plate.

[0006]

In the above-described liquid combustion burner, the combustion air 4 is jetted from the tip of the combustion cylinder 2 in the axial direction thereof, and the fuel 16 is simply injected from the nozzle 12 toward the downstream side. Just fire
Is shown in FIG. 14 up to the middle, but it becomes elongated along the axis of the burner.

However, in recent years, as boilers and the like tend to save space and reduce costs, the combustion chambers of boilers and the like are also changing to those having shorter depth dimensions. However, the conventional burner shown in FIG. 14 cannot meet this demand because the flame 18 is elongated.

Accordingly, it is a main object of the present invention to provide a liquid combustion burner which can shorten the flame.

[0009]

In order to achieve the above object, a liquid combustion burner according to the present invention is characterized in that the flame stabilizing plate is formed in a three-dimensional shape whose central part is recessed toward the upstream side, and the flame stabilizing plate is located downstream of the flame stabilizing plate. vaporization flame holding plate so as to face the flame stabilization plate near the side provided, it forms a pre-combustion space both flame holding plates, teeth
The distance from the tip of the combustion cylinder to the front of the flame holding plate
A, distance from the vaporized flame holding plate to the front surface of the flame holding plate
B, the inner dimension of the combustion cylinder is C, the outer dimension of the vaporization flame holding plate
When the method is D, the ratio A / C falls within the range of 0 to 0.4.
And the ratio B / C is in the range of 0.05 to 0.35, and
The ratio D / C is in the range of 0.5 to 1.0 .

[0010] According to the above configuration, most of the fuel injected from the nozzles strikes the vaporizing flame holding plate provided on the downstream side and is vaporized and accelerates toward the outer peripheral direction.
An annular flame is formed from the pre-combustion space toward the outer periphery thereof. On the other hand, the combustion air is ejected substantially axially from the outlet of the combustion cylinder, so that the flame going in the outer peripheral direction and the combustion air flowing in the axial direction are synthesized, and the pre-combustion is generated near the exit of the combustion cylinder. A cone-shaped flame that spreads greatly from the space toward the oblique downstream side is formed. as a result,
Flame can be shortened.

[0011]

FIG. 1 is a sectional view showing an example of a liquid combustion burner according to the present invention. Parts that are the same as or correspond to those in the conventional example of FIG. 14 are denoted by the same reference numerals, and differences from the conventional example will be mainly described below.

In this embodiment, the above-described combustion cylinder 2
A flame holding plate 26 corresponding to the conventional flame holding plate 6 is provided in the vicinity of the front end portion inside. In this example, the flame holding plate 26 has a mortar shape (in other words, a conical shape) in which the vicinity of the center portion is concave toward the upstream side. A hole 2 is formed in the center of the flame holding plate 26 almost.
In this example, the nozzle 12 described above is provided near the upstream side of the hole 28, and the fuel 1 injected from the nozzle 12 is provided.
6 is injected to the downstream side of the flame holding plate 26 through the hole 28. From this hole 28, the combustion air 4 is also supplied slightly downstream. When the combustion amount is large, a plurality of small holes 2 for ventilation are formed in the surface of the flame holding plate 26.
9 or a slit may be provided, but when the combustion amount is small, the small hole 29 or the slit is unnecessary.

In this embodiment, the above-described annular air port 10 is formed between the outer peripheral portion of the flame holding plate 26 and the above-mentioned inner wall of the combustion tube 2.

Further, in the present embodiment, a disk-shaped vaporizing flame holding plate 30 is provided near the downstream side of the flame holding plate 26 so as to face the flame holding plate 26. A pre-combustion space 32 is formed between the plate 30 and the flame holding plate 26. The central axes of the vaporization flame holding plate 30 and the flame holding plate 26 are, in this example, also the nozzle 12
Are arranged substantially on the central axis.

In this liquid combustion burner, the nozzle 1
Most of the fuel 16 sprayed from the fuel tank 2 hits the vaporization flame holding plate 30 provided on the downstream side and goes to the outer peripheral direction (see the arrow E), so that the annular flame 18 from the pre-combustion space 32 to the outer peripheral direction. Is formed. on the other hand,
Since the combustion air 4 is ejected from the outlet of the combustion cylinder 2 substantially in the axial direction (see arrow F), the flame 18 heading in the outer peripheral direction and the combustion air 4 flowing in the axial direction are synthesized (more). The flame 18 is directed obliquely outward as indicated by the arrow G, and flows obliquely downstream from the pre-combustion space 32 near the outlet of the combustion tube 2 as indicated by the arrow G. Flame 1 Spreading Radially Large
8 are formed. As a result, the flame 18 can be shortened, that is, the flame can be shortened.

In this case, unlike the case where the flame holding plate 26 is formed in a three-dimensional shape as described above, a relatively large volume of pre-combustion is provided between the flame holding plate 26 and the vaporized flame holding plate 30. A space 32 is formed, and the heat generated by the combustion (pre-combustion) of the fuel 16 there causes the fuel 1 sprayed there.
6 is promoted. In addition, on the downstream side of the vaporization flame holding plate 30, the above-described flame 18 and the air flow (see arrow F) ejected from the air port 10 on the outer peripheral portion of the flame holding plate 26 cause the exhaust gas circulation flow as shown in the illustrated example. 34 is generated and the vaporization flame holding plate 30 is heated by the heat of the exhaust gas circulating flow 34, so that the vaporization of the fuel 16 in the pre-combustion space 32 is further promoted. Therefore, even if the vaporization flame holding plate 30 is provided, the vaporization of the fuel 16 sprayed from the nozzle 12 is not hindered by the provision thereof, but rather, the vaporization of the fuel 16 is promoted by the above-described operation. The combustion of 16 is better.

As a result, the flame 18 spreads largely in a conical shape as described above, and as a result, the thickness of the flame 18 becomes thin and becomes a so-called thin film flame. When a thin-film flame is formed, the heat exchange between the thin-film flame and a combustion furnace such as a boiler is improved, and the combustion temperature of the flame 18 is reduced, so that the NOx (nitrogen oxide) concentration in the exhaust gas is reduced. In addition, the provision of the vaporizing flame holding plate 30 generates the exhaust gas circulating flow 34 as described above, whereby a part of the exhaust gas is recirculated into the flame 18, and becomes a so-called exhaust gas self-recirculation type. Since the combustion temperature of the flame 18 decreases, the NOx concentration in the exhaust gas also decreases for this reason. By these two actions, in this burner,
Not only the flame is shortened, but the N in the exhaust gas is lower than that of the conventional burner.
The effect that the Ox concentration can be reduced is obtained.

FIGS. 2 and 3 show examples of the measurement results of the visible flame length and the visible flame width of the burners of the conventional example shown in FIG. 14 and the embodiment shown in FIG. 1, respectively. The visible flame length is a measurement of the length of a portion visually recognized as a flame. The same applies to the visible flame width, which in other words represents the thickness of the flame.

As can be seen from both figures, in the burner of the embodiment, the burner of the conventional example is higher than that of the conventional burner in all combustion ranges.
The visible flame length is small and the visible flame width is large. That is,
In the burner of the embodiment, a thick and short flame is obtained,
It can be seen that short flame is realized. Further, it can be seen that the effect of shortening the flame becomes more remarkable as the combustion amount increases. In both figures, the values of the visible flame length and the visible flame width have upper and lower values because the flame shape changes slightly when the air-fuel ratio during combustion changes, and the measurement results are slightly different due to visual observation. This is because there is variation.

FIG. 4 is a sectional view showing another example of the liquid combustion burner according to the present invention. FIG. 5 is a front view of the liquid combustion burner of FIG.

In this embodiment, the aforementioned air port 10 is
Instead of being annular, it is divided into a plurality of parts (five in the illustrated example) in the circumferential direction of the flame holding plate 26, and they are arranged substantially uniformly in the circumferential direction of the flame holding plate 26. The portion 11 that is not the air port is closed by, for example, providing a baffle plate. This air port 1
The number of divisions of 0 is not limited to a specific one,
For example, 4 to 12, usually 6 to 8,
The larger the inner diameter of, the larger the number of divisions.

When the air port 10 is divided as described above, the downstream side of the air port 10 becomes an air-rich region and no flame is formed. Therefore, the flame 18 is divided radially as shown in FIG. It becomes a divided shape, that is, a divided flame. As a result, the combustion temperature of the flame 18 can be further reduced than in the embodiment of FIG.
The Ox concentration can be further reduced.

1 and 4, the distance A from the tip of the combustion cylinder 2 to the front surface of the flame holding plate 26 and the distance A from the vaporized flame holding plate 30 to the front surface of the flame holding plate 26. By adjusting the distance B, the shape of the flame 18 can be adjusted to a shape suitable for a combustion chamber such as a boiler. For example, as the distance A becomes smaller and the distance B becomes smaller, the flow of the fuel 16 in the outer peripheral direction becomes larger, so that the flame 18 can be further expanded and shortened.

The ratio A / C between the distance A, the distance B, the inner dimension C of the combustion cylinder 2 and the outer dimension D of the vaporizing flame holding plate 30,
NOx in exhaust gas depends on the size of B / C and D / C
Concentrations and combustion conditions change. The measurement results are shown in FIGS.
As shown in FIG. These are the measurement results of the burner in which the air port 10 is divided as shown in FIG. 4. However, in the case of the burner in which the air port 10 is not divided as shown in FIG. 1, except that the NOx concentration becomes slightly larger, The result of the similar tendency is obtained.

As can be seen from FIG. 6, the ratio A / C is 0 to 0.
When it is within the range of 0.4, the NOx concentration can be reduced to 80 ppm or less. Incidentally, the regulated value of the NOx concentration in exhaust gas in major cities such as Tokyo, Osaka and Nagoya is 80 ppm in the case of liquid fuel. Ratio A / C
The reason why the NOx concentration increases as the pressure increases is that the flame holding plate 26 is positioned deeper in the combustion cylinder 2 and the flame 18
It is considered that the spread of the gas becomes small and the combustion temperature becomes high.

As can be seen from FIG. 7, the ratio B / C is set to 0.0
When the concentration is within the range of 5 to 0.35, the NOx concentration becomes 80 pp.
m or less, and stable combustion can be maintained. When the ratio B / C is smaller than 0.05, the pre-combustion space 32 becomes narrow, combustion instability occurs there, and the NOx concentration increases. 0.35 ratio B / C
If it is larger than this, the effect of the vaporization flame holding plate 30 is reduced, and the combustion air 4 circulating from the outer peripheral portion of the flame holding plate 26 into the pre-combustion space 32 is relatively increased. And the NOx concentration increases.

As can be seen from FIG. 8, the ratio D / C is 0.5
When it is in the range of 1.0 to 1.0, the NOx concentration can be suppressed to 80 ppm or less and stable combustion can be maintained. When the ratio D / C is smaller than 0.5, the vaporization flame holding plate 30 becomes relatively small, the effect is reduced, and at the same time, the combustion coming around from the outer peripheral portion of the flame holding plate 26 into the pre-combustion space 32. The use air 4 becomes relatively large, combustion instability in the pre-combustion space 32 occurs, and the NOx concentration increases. When the ratio D / C is larger than 1.0, the combustion air 4 from the outer peripheral portion of the flame holding plate 26 hits the vaporized flame holding plate 30, causing unstable combustion in the pre-combustion space 32 and NOx. The concentration also goes up.

Regarding the case where the air port 10 is divided and the case where it is not divided, the following can be said.

That is, the shape of the vaporization flame holding plate 30 is not limited to the above-mentioned plate shape. For example, the downstream side has a concave dish shape as shown in FIG. 9, and the upstream side has a concave shape as shown in FIG. A dish shape or a conical shape with a concave downstream side as shown in FIG. 11 may be used. By doing so, the flow direction and the like of the fuel 16 sprayed from the nozzle 12 can be changed in various ways, so that the shape of the flame 18 and its combustion state can be changed in various ways. Further, the material of the vaporization flame holding plate 30 is not limited to a specific material, but may be, for example, metal or ceramic.

The vaporization flame holding plate 30 may be provided with a function such as heating, for example, by adding an electric heater. When the vaporization flame holding plate 30 is heated by an electric heater or the like, the vaporization of the fuel 16 at the time of ignition is further increased, and the fuel 16 is easily ignited, and the combustibility after ignition is also improved.

The shape of the flame holding plate 26 is not limited to the above-mentioned mortar shape. For example, as shown in FIG.
It may have a cylindrical shape with a bottom and an opening on the downstream side, more specifically a cylindrical shape with a bottom. In short, it may be a three-dimensional shape whose central part is concave toward the upstream side. By doing so, a relatively large volume pre-combustion space 32 can be formed between the flame holding plate 26 and the vaporized flame holding plate 30. The function and effect thereby are as described above.

Combustion cylinder 2, flame holding plate 26 and vaporization flame holding plate 3
The front shape of 0 is not limited to the circular shape in the above example, and may be another shape, for example, a polygon.

The position of the nozzle 12 is not limited to the vicinity of the upstream side of the flame stabilizing plate 26 as in each of the above-described examples. For example, as shown in FIG. That is, it may be in the pre-combustion space 32. This is because it is only necessary that the fuel 16 can be sprayed from the nozzle 12 to the downstream side of the flame holding plate 26. In this case, the hole 28 at the center of the flame holding plate 26 may be closed by the fuel supply pipe 13 to the nozzle 12. In this case, if ventilation to the downstream surface side of the flame holding plate 26 is insufficient, a plurality of small holes or slits may be provided in the plate surface of the flame holding plate 26 as described above.

The number of nozzles 12 is not limited to one as in each of the above examples, but may be two or more, such as 2, 3,.

The method of spraying the fuel 16 from the nozzle 12 is as follows.
Various systems such as a hydraulic spray system in which the fuel 16 is atomized only by hydraulic energy, a vapor spray system in which the fuel 16 is atomized by steam, and an air spray system in which the fuel 16 is atomized by air can be adopted.

[0036]

Since the present invention is configured as described above, it has the following effects.

According to the first aspect of the present invention, the fuel sprayed from the nozzle and directed toward the outer peripheral direction on the vaporizing flame holding plate and the combustion air flowing substantially axially from the outlet of the combustion cylinder are synthesized. In the vicinity of the outlet, a conical flame is formed which spreads greatly from the pre-combustion space toward the obliquely downstream side, so that the flame can be shortened.

Moreover, the spread of the flame as described above results in a thin-film flame, and the provision of the vaporizing flame-preventing plate generates an exhaust gas circulating flow, which reduces the combustion temperature of the flame. NOx concentration can be reduced. Further, the ratios A / C, B / C and
By setting D / C within the above range, N in the exhaust gas is reduced.
When the Ox concentration can be suppressed to 80 ppm or less,
In addition, stable combustion can be maintained.

According to the second aspect of the present invention, the flame is divided into radially divided flames, which further lowers the combustion temperature of the flame, so that the NOx concentration in the exhaust gas can be further reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a liquid combustion burner according to the present invention.

FIG. 2 is a diagram showing an example of a measurement result of a visible flame length.

FIG. 3 is a diagram showing an example of a measurement result of a visible flame width.

FIG. 4 is a sectional view showing another example of the liquid combustion burner according to the present invention.

FIG. 5 is a front view of the liquid combustion burner of FIG. 4;

FIG. 6 shows the NOx concentration (O ₂
FIG. 10 is a diagram showing an example of a measurement result of (= 0% conversion).

FIG. 7 shows the NOx concentration (O ₂
FIG. 10 is a diagram showing an example of a measurement result of (= 0% conversion).

FIG. 8 shows the NOx concentration (O ₂
FIG. 10 is a diagram showing an example of a measurement result of (= 0% conversion).

FIG. 9 is a view showing another example of the shape of the vaporization flame holding plate.

FIG. 10 is a view showing another example of the shape of the vaporization flame holding plate.

FIG. 11 is a view showing another example of the shape of the vaporization flame holding plate.

FIG. 12 is a view showing another example of the shape of the flame holding plate.

FIG. 13 is a diagram illustrating another example of a nozzle position.

FIG. 14 is a sectional view showing an example of a conventional liquid combustion burner.

[Description of Signs] 2 Combustion cylinder 4 Combustion air 10 Air port 12 Nozzle 16 Fuel 18 Flame 26 Flame holding plate 30 Vaporizing flame holding plate 32 Pre-combustion space

Claims (2)

(57) [Claims] A combustion cylinder to which combustion air is supplied from the outside, a nozzle provided in the combustion cylinder, to which a liquid fuel is supplied from the outside and which injects the fuel toward the end of the combustion cylinder;
A flame stabilizing plate provided near the nozzle in the combustion cylinder to stabilize the flame, and provided between the flame stabilizing plate and the inner wall of the combustion cylinder or near the periphery of the flame stabilizing plate and supplied to the combustion cylinder. An air port for ejecting the combustion air that has been blown from near the periphery of the flame holding plate to the downstream side,
The flame stabilizing plate is formed in a three-dimensional shape in which its central portion is recessed toward the upstream side, and a vaporized flame stabilizing plate is provided near the downstream side of the flame stabilizing plate so as to face the flame stabilizing plate. A pre-combustion space is formed , and the flame holding is performed from the tip of the combustion cylinder.
The distance to the front of the plate is A, and the flame holding plate is
The distance to the front of the plate is B, the internal dimension of the combustion cylinder is C,
When the outer dimension of the vaporized flame holding plate is D, the ratio A / C is 0 to
0.4, and the ratio B / C is in the range of 0.05 to 0.35.
Within the range, and the ratio D / C within the range of 0.5 to 1.0.
Liquid combustion burner, characterized by that. 2. The liquid combustion burner according to claim 1, wherein the air port is divided into a plurality of portions in the circumferential direction of the flame holding plate, and they are arranged substantially uniformly in the circumferential direction of the flame holding plate.