JPH0544568B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a gas fuel combustion device, and particularly to a gas fuel combustion device suitable for stabilizing a flame when burning gaseous fuel. .

(Prior Art) A conventional example of a gas fuel combustion device is shown in FIG. The gas fuel 1 is injected from the nozzle portion 2 into the furnace 15 and burned. Combustion air is pressurized by a fan and is supplied to the wind box 6 through an air duct. The wind box 6 is composed of a wind box wall 7 and a furnace wall 8.
A part of the combustion air supplied to the wind box 6 is introduced from the primary air intake port 10 whose opening area is adjusted by the primary slide damper 9, and is introduced into the primary air nozzle 1.
1 to the furnace 15.

An impeller 5 is provided at the center of the primary air nozzle 11, and the optimum position can be adjusted by moving the impeller rod 4 left and right in the drawing. The remaining combustion air is supplied to the air register 12, where the swirl strength and air volume are adjusted, and then supplied to the furnace 15 from the secondary air nozzle 13. A nozzle section 2 is installed in the secondary air nozzle 13, from which the gas fuel 1 is also injected.

FIG. 8 shows a view from A in FIG. 7.
An impeller 5 is provided at the center of the burner, and a secondary air nozzle 13 is arranged on the outer periphery of the impeller 5. Eight nozzle parts 2 and a frame holder 25 are provided in the secondary air nozzle 13.

FIG. 9 is a detailed view of the conventional gas fuel nozzle section 2, and is an enlarged view of section C in FIG. 7. A main injection hole 19 for gas injection is provided at the tip of the gas fuel supply nozzle body 17, and a sub injection hole 27 is provided in the nozzle body 17 upstream of the nozzle 19, as shown in FIG. Most of the fuel is injected into the furnace from the main injection hole 19 to form a main fuel flame. On the other hand, a small portion of the fuel flows from the sub-injection hole 27 to the center of the burner port, that is, to the impeller 5.
is injected toward the immediate trailing region, including onto the surface of the
A cup-shaped frame holder 25 with an open tip is attached to the upstream portion of each injection hole of the gas fuel supply nozzle body 17 by a frame holder guide 20, and the frame holder guide 20 covers the outer periphery of the nozzle body 17. It's on.

In a combustion apparatus having such a configuration, when the primary air flows around the impeller 5 provided at the center of the primary air nozzle 11 toward the furnace from left to right in the figure, the wake of the impeller 5 flows from left to right in the figure toward the furnace. , a vortex is generated that entrains a portion of the primary air. Most of the fuel injected from the auxiliary injection hole 27 reaches the vortex generated in the wake of the impeller 5 and is combusted. As a result, as shown in FIG. 8, a kind of flame zone is formed in the trailing region of the impeller 5 between the impeller 5 and the eight nozzles 2 surrounding it. As a result, the main injection hole 19 of the nozzle 2
The main fuel injected from the main fuel is constantly supplied with spark from the flame zone, ensuring stable combustion. On the other hand, a small portion of the fuel injected from the sub-injection hole 27 is drawn into the frame holder 25 and forms a flame. This flame is the sub-injection hole 2
7. Furthermore, it serves as a spark for the fuel injected from the seed injection hole 19.

(Problems to be Solved by the Invention) In the conventional gas combustion device shown in FIG. It was simply done by involving them. Therefore, the flame holding effect of the frame holder 25 was extremely weak.

The second drawback of the prior art is that the combustion air temperature is generally about 300°C and the gas fuel temperature is 20-50°C, and the frame holder guide 20 in contact with the former is
A difference in expansion based on the temperature difference occurs between the gas fuel supply nozzle body 17 in contact with the latter, and as this temperature difference changes, the difference in expansion changes, and the relative position between the frame holder 25 and the sub-injection hole 27 changes. ,
Since the amount of gas fuel drawn into the flame holder 25 changes, the flame may become unstable depending on the application conditions.

The third drawback of the prior art is that in order to perform low NOx combustion, combustion exhaust gas from the outlet of a combustion furnace (e.g. boiler) is mixed with primary air and secondary air to reduce the oxygen concentration of the mixture (e.g. Mix approximately 15% of the combustion exhaust gas to reduce the oxygen concentration of the combustion air to 21%.
%), the ignitability of the fuel deteriorates, a stable flame is not formed, and draft fluctuations in the furnace are more likely to occur due to flame fluctuations. It had a point. This means that if you increase the supplied gas pressure and increase the gas flow rate from the gas injection holes (main injection holes, sub injection holes) (in other words, this corresponds to increasing the furnace load), draft fluctuations in the furnace will occur. However, there was a problem that combustion vibration occurred in the furnace.

(Objective of the Invention) An object of the present invention is to provide a gas fuel combustion device that eliminates the drawbacks of the prior art described above, can cope with a wide range of operating conditions, and can provide a stable flame.

(Means for Solving the Problems) In short, the present invention provides a gas fuel injection nozzle equipped with a frame holder, in which the fuel injected from the sub-injection hole is reliably ignited immediately after the injection hole. An auxiliary injection hole is provided on the upstream side of the fuel injection hole or around the auxiliary injection hole, and if necessary, a fuel injection hole is also provided in the gas fuel supply main body part covered by the frame holder to ensure that it is inside the frame holder. In addition to supplying flame-stabilizing fuel, a flame-stabilizing member is provided at the tip of the frame holder to stabilize the flame.

That is, the present invention provides a furnace wall having a burner throat, a wind box wall located apart from the furnace wall and forming a wind box for flowing combustion air to the burner throat together with the furnace wall, and a wind box wall in the wind box. In a gas fuel combustion device that is provided in a combination of a combustor that supplies gas fuel for fuel, the combustor has a main injection hole and a large and auxiliary injection hole toward the rear from a front end on the furnace side. , and is composed of a gas supply nozzle main body equipped with a small sub-injection port near the large sub-injection port, and a frame holder guide provided on the outside thereof and having a cup-shaped frame holder with a front opening at the front end on the furnace side. The frame holder is characterized in that it is provided with one or more air intake ports.

(Example) An example of the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view showing a specific example of a gas burner to which the present invention is applied, and the difference from FIG. 7 lies in the way combustion air is supplied. That is, the volume of secondary air is adjusted by the secondary air register 12a, the swirling direction and swirling strength are adjusted by the secondary vane 12C, and the secondary air is supplied to the furnace 15 from the secondary air nozzle 13. The remaining combustion air is supplied to the furnace 15 through the tertiary air nozzle 16 after its air volume and swirl strength are adjusted by the tertiary air register 12b. Regarding the primary air, it is the same as in the case of FIG.

FIG. 2 is a view from B in FIG. 1, showing a front view of the burner seen from the furnace 15 side. An impeller 5 is provided on the burner axis, with an annular primary air nozzle 11 on its outer periphery, an annular secondary air nozzle 13 on its outer periphery, and an annular tertiary air nozzle 16 on its outer periphery.
is provided. The burner throat 14 has a tapered shape and opens in the furnace wall 8, and is provided outside the tertiary air nozzle 16. The gas fuel nozzle 2 is connected to the tertiary air nozzle 16 as shown.
They are arranged to form a combustor.

FIG. 3 shows a detailed view of section A in FIG. 1. A main injection hole 19, a large injection hole 27, a small sub injection hole 21, and a flame holding hole 22 are provided at the tip of the gas supply nozzle body 17. Further, the gas supply nozzle body 17 is provided with a cup-shaped frame holder 25 with an open end so as to cover the flame holding holes 22.
The flame is stabilized by the fuel injected from 1, 27, and 19. This frame holder 25 is provided with one or more air holes 24 to supply air to the inside of the frame holder 25.
A flame stabilizing plate 29 is provided at the tip of the frame holder 25 to stabilize the flame. Flame holding plate 29
Gaseous fuel necessary for combustion above is supplied from flame holding holes 22.

FIG. 4 is an enlarged view of the tip of the gas supply nozzle main body shown in FIG. 3. At the tip of the gas supply nozzle body 17, there are a small sub-injection hole 21 and a large sub-injection hole 2.
7 and a main injection hole 19 are provided as shown. Gas fuel is ejected from the small sub-injection holes 21 and the large sub-injection holes 27 all toward the top of the impeller 5. That is, the gas fuel necessary for combustion on the impeller 5 is supplied from the small sub-injection holes 21 and the large sub-injection holes 27.

FIG. 5 shows the state of the flame formed by the gas ejected from the small sub-injection holes 21 and the large sub-injection holes 27 according to the present invention. Small sub injection hole 2
The gas ejected from 1 immediately diffuses, reacts with combustion air, and forms a small sub injection hole flame surface 30. This flame surface 30 surrounds the large and sub-injection hole gas flow 31 on the downstream side. On the other hand, the flame surface 3 of the large and sub-injection holes
2 is generated far away from the hole 27. The reason for this is that combustion does not occur within the gas flow of the large and sub-injection holes, which is a field where the flow velocity is faster than the combustion velocity of the gas. The main cause of the furnace draft fluctuation is the fluctuation phenomenon of the flame surface 32 of the large and auxiliary injection holes, which is formed away from the large and auxiliary injection holes 27. In order to reduce the intensity of this fluctuation, the flame surface 30 of the small and auxiliary injection holes is
By doing so, the ignition point of the gas jet from the large and auxiliary injection holes is kept constant, and flame fluctuations are reduced. The small auxiliary injection hole flame surface 30 can reduce the fluctuation strength of the large and auxiliary injection hole flame surface 32, and as a result, the furnace draft fluctuation can be suppressed to a low level.

Another embodiment of the sub injection hole according to the present invention is shown in FIG. A plurality of small sub-injection holes 21 are provided around the large and sub-injection holes 27. By doing this, the flame surface 3 generated by the gas jet of the major and sub-injection holes 27 is always generated for the air flow in any direction.
The fluctuation strength of No. 2 can be reduced.

(Effects of the Invention) According to the present invention, in a gas fuel combustion device equipped with a main injection hole and a sub-injection hole, the ignition of the fuel injected from the sub-injection hole is stabilized, and flame fluctuations are reduced. Ignition of the main fuel injected from the injection hole is also stabilized, and flame fluctuations are reduced. This reduces draft fluctuations within the furnace, making it possible to prevent the occurrence of combustion vibrations, which is a problem in boilers that use gas fuel.

Similarly, when performing low NOx combustion by mixing combustion exhaust gas into the combustion air, it is possible to ensure the ignitability of the burner and reduce flame fluctuations. The rate can also be varied over a wide range.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of a gas combustion device to which the present invention is applied, FIG. 2 is a view from B in FIG. 1,
3 is a detailed view of part A in FIG. 1, FIG. 4 is an enlarged explanatory view of the tip of the gas nozzle in FIG. 3, FIG. 6 is a diagram showing another embodiment of the gas nozzle part in the present invention, FIG. 7 is a sectional view of a conventional gas fuel combustion device, and FIG. 8 is a view from A in FIG. 7.
FIG. 9 shows a detailed view of section C in FIG. 7. 1...Gas fuel, 2...Gas fuel nozzle, 5...
... Impeller, 6... Wind box, 7... Wind box wall, 8...
Furnace wall, 11... Primary air nozzle, 13... Secondary air nozzle, 14... Burner throat, 15... Furnace, 16... Tertiary air nozzle, 17... Gas supply nozzle body, 19... Main injection hole , 21... Small sub injection hole, 22... Flame holding hole, 25... Frame holder,
27...Large and sub-injection holes, 29...Flame holding plate.

Claims (1)

[Claims] 1. A furnace wall having a burner throat, a wind box wall located apart from the furnace wall and forming a wind box for flowing combustion air to the burner throat together with the furnace wall, and a wind box wall provided in the wind box and provided with a gas In a gas fuel combustion device combining a combustor that supplies and burns fuel, the combustor has a main injection hole and a large and auxiliary injection hole toward the rear from the front end on the furnace side,
and a gas supply nozzle body equipped with a small auxiliary injection port near the large and auxiliary injection holes, and a frame holder guide provided on the outside thereof and having a cup-shaped frame holder with a front opening at the front end on the furnace side,
A gas fuel combustion device, characterized in that the frame holder is provided with one or more air intake ports.