JPH0481081B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel duct burner for a gas turbine boiler, a small capacity burner for burning gas fuel, and the like.

A conventional example will be explained with reference to FIGS. 1 and 2. A wide air guide vane 01 is provided on one side of a fuel pipe 03, and a slit-shaped gap is provided between the fuel pipe 03 and the base of the air guide vane 01. In addition to providing 02,
Dots 09 are placed at several locations between the fuel pipe 03 and the air guide vane 01.

The fuel pipe 03 is provided with a plurality of fuel injection holes 04 along the air guide vanes 01, and is provided with a premixed air chamber 05 surrounded by the fuel pipe 03, the fan-shaped air guide vanes 01, and the front plate 05B. The fuel gas ejected through the gap 04 and the combustion air flowing in through the gap 02 are mixed to form a premixture.

A plurality of premixture nozzle holes 07 are provided on the front plate 05B of the premixture chamber 05, a flame stabilizer 06 is provided on the extension of the air guide vane 01, and a large number of reinforcing plates 08 are provided in the direction perpendicular to the flame stabilizer. will be established.

The fuel gas is ejected into the premixing chamber 05 through the fuel injection hole 04 of the fuel pipe 03, and mixes with the combustion air that has flowed in through the slit-shaped gap 02 to form a premixture. The mixture in the premixture chamber 05 is ejected through the premixture nozzle hole 07 provided on the front plate 05B, and the premixture is stabilized by the circulation flow inside the flame stabilizer 06 and the diffusion of combustion air from the surroundings. maintains a burning sensation.

FIG. 3 shows that it is very difficult to perform combustion in a region where the value V of the flame propagation velocity curve C is smaller than a certain value v, that is, at points where the air ratio is smaller than point A and the air ratio is larger than point B. The area above a certain value v indicates a stable combustion region, and the area below v indicates an unstable combustion region.

In addition, the amount Wg of the gaseous fuel in the fuel pipe 03 that is ejected from the fuel injection hole 04 is as shown in FIG.
3 and the premixing chamber 05, so if the fuel air flow rate is constant and the diameters of the fuel nozzles 04 are the same in all the fuel nozzles 04, the premixing chamber 05 The air ratio of the premixture jetted out from the premixture nozzle hole 07 provided in the fuel pipe is the same for all holes, and the value of the air ratio is the same for all the holes.
Determined only by the pressure within 3.

Therefore, the operating range of the fuel gas pressure within the fuel pipe 03 is greatly limited by the flow rate of combustion air and the oxygen concentration in the air. In other words, there is a problem in that a large turndown cannot be achieved.

An object of the present invention is to provide a gas-fired duct burner device that can achieve a sufficiently large turndown without complicating the structure and without limiting the flow rate of combustion air or the oxygen concentration in the air.

The present invention will be explained with reference to the embodiments shown in FIGS. 5, 6 and 7 of the accompanying drawings.

A wide air guide vane 1 is provided on one side of the fuel pipe 3, and a slit-shaped gap 2 is provided between the fuel pipe 3 and the base of the air guide vane 1.
and the air guide vane 1 are fixed by fixing plates 9 at several places. A plurality of large-diameter fuel injection nozzle holes 4A and a plurality of small-diameter fuel injection nozzle holes 4B are alternately provided on the front surface of the fuel pipe 3.

Also, the fuel pipe 3, the air guide vane 1, and the front plate 5B
A premixture chamber 5 is formed by surrounding the premixture chamber 5. A plurality of premixture jet nozzle holes 7A having a large hole diameter and premixture jetting nozzle holes 7B having a small hole diameter are alternately provided on the front plate 5B of the premixture chamber 5.

Further, a flame stabilizer 6 is provided on the extension of the air guide vane 1,
The flame stabilizer 6 is provided with a plurality of reinforcing plates 8 for reinforcement and for preventing flame fluctuation in the duct width direction.

The difference between this embodiment and the conventional example is that the fuel pipe 3 has two nozzle holes 4A and 4 with different diameters, whereas the fuel pipe 3 has a plurality of nozzle holes 04 with the same diameter.
B are provided alternately, and furthermore, the premixture chamber 0
5, the nozzle holes 7A with a large diameter and the nozzle holes 7B with a small diameter are alternately arranged on the front plate 5B of the premixture chamber 5.

However, as shown in Figures 6 and 7, the fuel pipe 3
Nozzle holes 4A, 4B and premixture chamber 5 provided in
The sizes of the nozzle holes 7A and 7B provided in the front plate 5B do not necessarily have to be limited to two sizes, large and small. That is, the type may be changed as described below.

Next, the operation of the present invention will be explained. A part of the combustion air flows into the premixing chamber 5 through the slit-shaped gap 2 between the fuel pipe 3 and the air guide vane 1.

The fuel gas is supplied through nozzle holes 4A, 4 provided in the fuel pipe 3.
B is injected into the premixture chamber and mixed with combustion air that has flowed in through the slit-shaped gap 2 to form a premixture.

The mixture of fuel gas and combustion air in the premix 5 is injected to the flame stabilizer 6 through nozzle holes 7A and 7B provided in the front plate 5B.

The premixed gas ejected from the nozzle holes 7A and 7B maintains stable combustion due to the circulating flow inside the flame stabilizer 6 and the diffusion of combustion air from the surroundings.

In FIG. 8, in the conventional type, the diameter of the nozzle hole 07 is the same, so the operating range is from point A to point B. The operating range of the present invention is from point A to point B' of the premixture jetted out from the small diameter nozzle hole 7B, and from point A' to point B of the premixture jetted out from the large diameter nozzle hole 7A. The total operating range is wider than the conventional operating range.

In other words, the premixture injected from the large-diameter nozzle hole 7A has a low flame propagation velocity at high pressures such as from point A to point A' and belongs to the unstable combustion region, but at this pressure it is ejected from the small-diameter nozzle hole 7B. The premixture that is produced belongs to the stable combustion region from A'' to A where the flame propagation velocity is high. Therefore, the premixture that is injected from the large diameter nozzle hole 7A located next to the small diameter nozzle 7B also flows through the small diameter nozzle hole. The fragile flame from 7B allows for stable combustion.

Similarly, the premix injected from the small-diameter nozzle hole 7B has a low flame propagation velocity at a low pressure such as from point B to point B', and belongs to the unstable combustion region, but at this pressure, the premixture is ejected from the large-diameter nozzle hole 7A. The ejected premixture belongs to stable combustion at point B from B'' where the flame propagation velocity is high.Therefore, the premixture ejected from the small diameter nozzle hole 7B located next to the large diameter nozzle hole 7A also has a large diameter. Stable combustion can be achieved by the ignition of the flame from the nozzle hole 7A.

Therefore, the turndown can be dramatically increased simply by drilling holes in the conventional burner structure without making the flame holder structure complicated.

In the above embodiment, there was an example in which the nozzle holes 4A, 4B or 7A, 7B of different sizes were bored alternately in the axial direction in both the fuel pipe 3 and the front plate 5B of the premixing chamber 5. Nozzle holes 4A, 4 of pipe 3
Nozzle holes 7A and 7 of the front plate 5B with the same B diameter.
Large and small nozzle holes 7A and 7B with different hole diameters only for B
It is also possible to do this. Note that the nozzle holes 7A and 7B of the front plate 5B may have the same diameter, and the nozzle holes 4A and 4B of the fuel pipe 3 may have different diameters.

[Brief explanation of the drawing]

Figure 1 is a vertical front view of the conventional example, Figure 2 is a side view taken along the - line in Figure 1, Figure 3 is a general flame propagation velocity curve diagram of premixed gas fuel, and Figure 4 is a view from the fuel pipe. Graph showing the performance of ejected fuel, FIG. 5 is a longitudinal sectional front view of the present invention, FIG. 6 is a side view taken along the - line in FIG. 5, FIG. 7 is a sectional view taken along the - line in FIG.
The figure shows a flame propagation characteristic diagram of the premixed gas fuel of the present invention. 1... Air guide vane, 2... Gap, 3... Fuel pipe, 4A, 4B... Fuel injection nozzle hole, 5... Premixture chamber, 5B... Front plate, 6... Flame stabilizer, 7
A, 7B... Premixture jet nozzle, 8... Reinforcement plate, 9... Fixed plate.

Claims (1)

[Claims] 1. An air guide vane is provided in the fuel pipe through a gap,
In the device in which a premixture chamber is formed by the fuel pipe, the air guide vane, and the front plate, and a flame stabilizer is provided at the tip of the air guide vane, the fuel pipe and the front plate have holes of different diameters. A gas-fired duct burner device characterized in that a plurality of fuel injection nozzle holes and a plurality of premixture injection nozzle holes with different hole diameters are provided alternately.