JPH0113224Y2 - - Google Patents

Description

[Detailed explanation of the idea]

Industrial Application Field The present invention relates to a nozzle for a natural draft low NO _x burner. BACKGROUND ART As shown in FIG. 3, a conventional low NO _x burner nozzle 1 has a cylindrical main chamber 3 having a fuel gas supply port 2 at one end, and a pilot chamber 5 connected to the other end of the main chamber 3 via a partition wall 4. A plurality of main nozzles 6 are formed in the peripheral wall of the main chamber 3 in the radial direction, a communication hole 7 is formed in the partition wall 4, and a plurality of pilot nozzles 8 are formed in the peripheral wall of the pilot chamber 5 in the radial direction. It was drilled in the Problems to be solved by the invention According to the above conventional configuration, the burner is a forced draft type
In the case of NO _x burners, the desired performance is achieved, but
In the case of natural ventilation type low NO _x burners, the low air flow rate reduces the premixability of fuel gas and air, which causes the problem that sufficient performance cannot be achieved. An object of the present invention is to provide a burner nozzle that solves the above problems. Means for Solving the Problems In order to solve the above problems, the burner nozzle of the present invention has a cylindrical main chamber having a fuel gas supply port at one end, and a pilot chamber formed at the other end through a partition wall. In the burner nozzle, a plurality of main nozzles are formed in the peripheral wall of the main chamber, a communication hole is formed in the partition wall, and a plurality of pilot nozzles are formed in the peripheral wall of the pilot chamber, An inner cylinder is inserted into the main chamber from the supply port, and the main nozzle is inclined toward the pilot chamber at an ejection angle of 60 degrees or less with respect to the peripheral wall of the main chamber. It is. Function In the above configuration, fuel gas is supplied into the main chamber from the supply port via the inner cylinder, and is ejected from the main nozzle in the direction of the ejection angle. promotes premixing of The air-fuel mixture thus obtained becomes a quasi-premixed state close to complete premixing up to the pilot nozzle, and is ignited by the pilot flame in the pilot nozzle, resulting in continuous and stable combustion. In addition, the combustion gas exiting the inner cylinder cools the nozzle tip to extend the nozzle life, and is uniformly supplied to the main nozzle even at low flow speeds during burner turndown (low flow rate). It is squirted. Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. The burner nozzle 10 of this embodiment includes a main chamber 11, a pilot chamber 12, and an inner cylinder 13, as shown in FIG. The main chamber 11 is a cylindrical body such as a cylinder or a rectangular tube, and has a fuel gas G supply port 14 at one end, and a plurality of main nozzles 16 are installed on a peripheral wall 15 at an ejection angle θ with respect to the peripheral wall 15. room 12
The pilot chamber 12 is formed at the other end with a partition wall 17 interposed therebetween. Bulkhead 1
A communication hole 18 is bored in the center of the hole 7 .
The pilot chamber 12 is also a cylindrical body such as a cylinder or a rectangular tube, and a plurality of pilot nozzles 20 are bored in the peripheral wall 19 in the radial direction. The inner cylinder 13 is inserted into the main chamber 11 through the supply port 14, passes through the main nozzle 16, and opens near the partition wall 17. The ejection angle θ is set in consideration of the distance L to the pilot nozzle 20 and the relationship with the burner tile, which will be described later, but in order to maximize the aspiration effect, which is a feature of the present invention, it is set to 60 degrees or less. must be taken as such. Hereinafter, the effects of the above configuration will be explained. As shown in _FIG . 2, the natural ventilation type low NO
A guide vane 24 is fixedly installed, and a burner tile 26 is stretched in a conical shape on the peripheral wall on the side of the combustion chamber 25.
The burner nozzle 10 of this embodiment has guide vanes 24
A fuel gas pipe 27 is connected to the supply port 14 . First, a small amount of fuel gas G is supplied into the pilot chamber 12 from the fuel gas pipe 27 via the inner cylinder 13, the main chamber 11, and the communication hole 18, flows out from the pilot nozzle 20, is ignited, and produces a pilot flame 28. is generated. Next, the fuel gas G at the flow rate necessary for normal combustion is supplied from the fuel gas pipe 27 through the inner cylinder 13 into the main chamber 11, and a portion of it is supplied into the pilot chamber 12 in the same manner as above. to hold the pilot flame 28. Most of the remaining part makes a U-turn and is ejected from the main nozzle 16 in the direction of the ejection angle θ, sucks the surrounding air A supplied via the guide vane 24 by the aspiration effect, and is mixed with the air A. Promote premixing. The air-fuel mixture thus obtained becomes a quasi-premixed state close to perfect premixing while flowing over a distance L, and is ignited by the pilot flame 28, resulting in continuous stable combustion. In addition, the fuel gas G that has exited the inner cylinder 13 cools the tip of the nozzle 10 itself to extend the life of the nozzle, and also reaches the main nozzle 16 even in a low flow rate state when the burner 21 is turned down (low flow rate). Evenly supplied and ejected evenly. By the way, normal burners that do not have the NO _x countermeasures taken by the inventor of this invention, conventional low NO _x
The table below shows the results of a comparative combustion test under natural ventilation using a burner and a low NO _x burner using the nozzle of the present invention.

[Table] Shows the ratio of minimum combustion amount when
As is clear from the above table, by using the nozzle of this invention, it is possible to
The premixability of air and fuel gas has been significantly improved, and overall performance has been significantly improved, including lower _NOx , lower _O2 , and an expanded turndown range. Effects of the invention As described above, according to the invention, fuel gas is ejected obliquely from the main nozzle toward the pilot nozzle, so the surrounding air is sucked by the aspiration effect, and premixing with the air is prevented. promoted. In addition, the fuel gas exiting the inner cylinder cools the nozzle tip to extend the nozzle life, and is also supplied to the main nozzle without deviation even at low flow speeds.
Sprayed evenly. Therefore, the lower limit of burner turndown is expanded, and a stable combustion state can be ensured over a wide combustion range, resulting in an excellent effect of reducing _NOx and energy saving in a natural draft burner.

[Brief explanation of the drawing]

Figure 1 is a sectional view of a burner nozzle showing an embodiment of the present invention, Figure 2 is a sectional view of a natural draft low _NOx burner using the present invention, and Figure 3 is a sectional view of a conventional low NOx burner.
FIG. 3 is a sectional view showing an example of a NO _x burner. 10... Burner nozzle, 11... Main chamber, 12
... Pilot chamber, 13 ... Inner cylinder, 14 ... Supply port, 15 ... Peripheral wall, 16 ... Main nozzle, 17
...Partition wall, 18...Communication hole, 19...Peripheral wall, 20
...Pilot nozzle, G...Fuel gas, θ...
Spout angle.

Claims (1)

[Scope of utility model registration request] A pilot chamber is formed at the other end of a cylindrical main chamber having a fuel gas supply port at one end via a partition wall, a plurality of main nozzles are bored in the peripheral wall of the main chamber, and a communication hole is formed in the partition wall. In the burner nozzle in which a plurality of pilot nozzles are bored in the peripheral wall of the pilot chamber, an inner cylinder is inserted into the main chamber from the supply port, and the main nozzle is inserted into the peripheral wall of the main chamber. A burner nozzle, characterized in that the burner nozzle is inclined toward the pilot chamber with an ejection angle of 60 degrees or less.