JPS6262114A - Gas fuel burning device - Google Patents

Abstract

PURPOSE:To enable production of stable fire flames corresponding to wide operating condition by installing an auxiliary injection hole at the upper flow side or the circumference of a secondary injection hole. CONSTITUTION:A burning device is constituted of a gas supply nozzle mainbody 17 which has a main injection hole 19 and a large secondary injection hole 27 at the backward side of a tip part in the furnace side, and further has a small secondary injection hole 21 near the large secondary injection hole 27, and a flame holder guide which is placed at the outside of the nozzle mainbody and has a cup-shaped flame holder that has a front opening at a tip part in the furnace side, and one or more air intake holes 24 are formed in the flame holder 25. Gas injected from the small secondary injection hole 21 is quickly diffused and forms a fire flame surface 30 at the small secondary injection hole after gas is reacted with burning air. As gas flow 31 at the large secondary injection hole is covered by the fire flame surface 30 at the small secondary injection hole, the ignition point is in a constant distance from the large injection hole and wavering of flame is small and change of draft in the furnace can be kept in a lower range.

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. gas fuel 1
is injected from the nozzle portion 2 into the furnace 15 and burned. Combustion air is pressurized by a fan and 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 through the primary air intake port 10 whose opening area is adjusted by the secondary slide damper 9, and is introduced into the large air nozzle 11.
is supplied to the furnace 15.

An impeller 5 is provided at the center of the primary air nozzle 11,
By moving the impeller rod 4 left and right in the drawing,
The optimal position can be adjusted. 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 through the secondary air nozzle 13. The secondary air nozzle 13 includes a nozzle portion 2
is installed, and gas fuel 1 is also injected from here.

Figure 8 shows Homeland A in Figure 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 shows details of the conventional gas fuel nozzle section 2, and is an enlarged view of part 0 of 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 2 is provided in the nozzle body 17 on the upstream side of the gas fuel supply nozzle body 17.
7 is provided as shown in FIG. Main injection hole 19
From there, most of the fuel is injected into the furnace, forming the main combustion flame. On the other hand, a small portion of the fuel is injected from the sub-injection hole 27 toward the center of the burner port, that is, toward the immediately downstream area including the surface of the impeller 5.

A cup-shaped frame holder 25 with an open end is connected to the gas fuel supply nozzle body 1 by a frame holder guide 20.
The frame holder guide 20 covers the outer periphery of the nozzle body 17.

In the combustion device having such a configuration, the secondary air nozzle 11
When the secondary air flows toward the furnace from left to right in the figure around the impeller 5 provided in the center of the impeller 5, a part of the secondary air is drawn into the wake of the impeller 5. A vortex like this occurs. 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 fuel injected from the main injection hole 19 of the nozzle 2 is constantly supplied with spark from the flame zone, ensuring stable combustion. On the other hand, the sub injection hole 27
A small portion of the fuel injected from the flame holder 25 is drawn into the flame holder 25 to form a flame. This flame is the sub-injection hole 2
7. Furthermore, it serves as a spark for the fuel injected from the main 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. For this reason, there was a drawback that 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 and the gas fuel supply nozzle body 17 in contact with the latter are During this period, an elongation difference occurs based on the temperature difference, and as this temperature difference fluctuates, the elongation difference changes, the relative position between the frame holder 25 and the sub-injection hole 27 changes, and the gas fuel into the frame holder 25 changes. As the amount of entrainment changes, the flame may become unstable depending on the prevailing conditions.

The third drawback of the conventional technology is that because it performs low NOx combustion,
- When operating by mixing combustion exhaust gas from the outlet of a combustion furnace (e.g. boiler) with secondary air and secondary air to lower the oxygen concentration of the mixture (for example, by mixing approximately 15% of combustion exhaust gas, the oxygen concentration of combustion air When burning gas fuel with the fuel temperature lowered from 21% to 17-18%), the ignitability of the fuel deteriorates, a stable flame cannot be formed, and draft fluctuations in the furnace are likely to occur due to flame fluctuations. It had some problems. 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) -
There was a problem in that this caused draft fluctuations in the furnace, causing combustion vibrations 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 which is provided in a combination of a combustor that supplies and burns gas 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 one or more air intake ports are provided.

(Example) Embodiments of the present invention will be described in detail using 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 in which combustion air is supplied. That is, after the volume of the 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 sent to the secondary air nozzle 13.
is supplied to the furnace 15. The remaining combustion air has its air volume and swirl strength adjusted by the tertiary air register 12b.
The tertiary air is supplied from the tertiary air nozzle 16 to the furnace 15 . Regarding the -order air, it is the same as in the case of Fig. 7.

FIG. 2 shows the front view of the burner seen from the furnace 15 side in B homeland of FIG. 1. Impeller 5 on the burner axis
is provided 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. The burner throat 14 has a tapered shape and opens in the furnace wall 8, and is provided outside the tertiary air nozzle 16. As shown in the figure, eight gas fuel nozzles 2 are arranged at the tertiary air nozzle 16 to constitute a combustor.

FIG. 3 shows a detailed view of section A in FIG. 1. A main injection hole 19, a large sub 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. Also,
The gas supply nozzle body 17 has a flame holding hole 22 covered with the gas supply nozzle body 17 .
A cup-shaped frame holder 25 with an open end is provided to stabilize the flame caused by the fuel injected from the gas injection holes 21, 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 holding plate 29 is provided at the tip of the frame holder 25 to stabilize the flame. Gaseous fuel necessary for combustion on the flame stabilizing plate 29 is supplied from the flame stabilizing 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, a large sub injection hole 27, 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 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. The gas ejected from the small sub injection hole 21 immediately diffuses, reacts with the combustion air, and forms the small sub injection hole flame surface 30.
form. 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 32 of the major and auxiliary injection holes is generated at a considerable distance 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 formed apart 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 covering the large and auxiliary injection holes gas flow 31, the ignition point of the gas jet from the large and auxiliary injection holes becomes constant and flame fluctuations are reduced.

The small sub injection hole flame surface 30 creates the large sub injection hole flame surface 3.
2 can be reduced, and as a result, the furnace draft fluctuation can be suppressed.

Another embodiment of the sub injection hole according to the present invention is shown in FIG.

A plurality of two small sub injection holes are provided around the large sub injection hole 27. By doing so, it is possible to always reduce the intensity of fluctuations in the flame surface 32 caused by the gas jets of the major and sub-injection holes 27 with respect to air flows in any direction.

(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 there is less fluctuation of the flame. The ignition of the main fuel injected from the main injection hole is also stabilized, and flame fluctuations are reduced.This reduces draft fluctuations in the furnace and reduces the occurrence of combustion vibration, which is a problem in boilers that use gas fuel. It can be prevented from happening.

Similarly, combustion exhaust gas is mixed into the combustion air to reduce NO.
Even when x-combustion is performed, the ignitability of the burner can be ensured and flame fluctuations can be reduced, making it possible to vary the mixing rate of exhaust gas mixed into the combustion air over a wide range.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an embodiment of a gas combustion device to which the present invention is applied, Fig. 2 is the homeland B of Fig. 1, Fig. 3 is a detailed view of part A of Fig. 1, and Fig. 4 is FIG. 3 is an enlarged explanatory view of the gas nozzle tip, FIG. 5 is a view explaining ignition of fuel injected from the gas nozzle in the present invention, and FIG. 6 is a view showing another embodiment of the gas nozzle part in the present invention. Figure 7 is a cross-sectional view of a conventional gas fuel combustion device, Figure 8 is the homeland A of Figure 7,
FIG. 9 shows a detailed view of C11J in FIG. 7. l...Gas fuel, 2...Gas fuel nozzle, 5...
Impeller, 6... Wind box, 7... Wind box wall, 8... Furnace wall, 11... Secondary 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...Major and sub-injection holes, 29...Flame holding plate. Agent Patent Attorney Takeshi Kawakita Figure 2

Claims (1)

[Claims] a furnace wall having a burner throat; a wind box wall located away from the furnace wall and forming a wind box together with the furnace wall for causing combustion air to flow to the burner throat; In a gas fuel combustion device that combines a combustor that supplies and burns fuel, the combustor has a main injection hole and a large and sub injection hole toward the rear from a front end on the furnace side, and a large and sub injection hole. It consists of a gas supply nozzle main body equipped with a small sub-injection port near the gas supply nozzle body, 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, and the frame holder has one nozzle. A gas fuel combustion device characterized by being provided with the above air intake port.