JP2794927B2 - Premixing method and premixing device for gas turbine combustor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a premixed gas turbine combustor for producing a mixture of air and fuel, and then supplying the mixture to a combustor body for combustion. And a premixing device.

[Conventional technology]

As a countermeasure against pollution of gas turbine exhaust, reduction of nitrogen oxides (hereinafter referred to as “NO _X ”) in gas turbine exhaust has become an important issue. In recent years, very stringent NO _X emissions have been required by regulations or regional agreements on the content of reducing nitrogen oxides in gas turbine exhaust. Conventionally, after a homogeneous mixture in which air and fuel are mixed at a predetermined ratio in a premixing device in advance is produced, and the mixture is supplied to a combustor body and burned, a lower temperature than in a diffusion combustion system is obtained. Combustion becomes possible and NO contained in gas turbine exhaust
It is known that _X can be reduced. Accordingly, in recent years, in order to reduce the amount of NO _x, premixed type combustor employing a lean premixing is used.

FIG. 5 is a schematic cross-sectional view showing an example of a conventional premixed type gas turbine combustor ("Journal of Gas Turbine Society of Japan, VO").
L.16 NO64 MAR.1989 "). As shown in the drawing, a conventional gas turbine combustor 13 includes a pilot combustor 14, a main combustor 15, and a bypass mechanism 19. 16 is a main fuel injection device, 17 is a premixing device, and 18 is a bypass curved pipe for introducing secondary air.

[Problems to be solved by the invention]

In the conventional premixed gas turbine combustor as described above, the premixing needs to keep the mixing ratio of fuel and air constant even at a partial load, and therefore the secondary air amount is reduced. The method of control is adopted. However, in this method, since the primary air amount is increased or decreased by controlling the secondary air amount, the response is slow, the mixing ratio of fuel and air is temporarily disrupted, and combustion instability is a problem. It has become. To prevent this, a required flame holding by a large amount of pilot fuel, which has led to increase in the amount of NO _X.

Accordingly, an object of the present invention is to solve the above-mentioned problems, to control the inflow of primary air with good responsiveness even at a partial load, and to maintain a constant fuel / air mixing ratio. It is an object of the present invention to provide a premixing method and a premixing device for a vessel.

[Means for solving the problem]

In order to achieve the above object, in the premixing method of the present invention, a circular swirler in which a plurality of primary air introduction holes for giving a swirling motion to combustion air are spirally bored,
A fuel injection nozzle is provided on a blade of the swirler that forms the air introduction hole, and an installation position of the fuel injection nozzle is an abdominal wall that is an inner peripheral side of the air introduction hole, and the fuel injection nozzle is disposed from the fuel injection nozzle. In a premixing method in a gas turbine combustor in which fuel is injected toward an air flow passing through an air introduction hole to perform premixing of air and fuel, a predetermined circumferential direction is provided on an outer peripheral surface of the circular swirler. An annular ring provided with a hole having substantially the same area as the opening of the primary air introduction hole is rotatably inserted at intervals, and the opening area of the primary air introduction hole is changed by rotating the ring. It is characterized in that the amount of air flowing into the primary air introduction hole is controlled.

Further, in the premixing device of the present invention, a circular swirler in which a plurality of air introduction holes for giving a swirling motion to the combustion air are helically drilled, and the swirler introduces air into the air introduction holes. A fuel injection nozzle for injecting fuel into the air to be blown, wherein the fuel injection nozzle is an abdominal wall which is an inner peripheral side of the air introduction hole of the swirler blade forming the air introduction hole. And a premixing device in a gas turbine combustor capable of injecting fuel toward an air flow passing through the air introduction hole, wherein an outer peripheral surface of the circular swirler has the primary air introduction In order to change the opening area of the hole, an annular ring provided with a hole having substantially the same area as the opening of the primary air introduction hole at a predetermined interval in the circumferential direction is rotatably inserted. It has.

Next, the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a sectional view taken along line AA of FIG. 1, and FIG. 3 is a sectional view taken along line BB 'of FIG. In the drawings, reference numeral 1 denotes a combustor of a gas turbine, which has a circular swirler 3 for giving a swirling motion to combustion air at a predetermined position on an upstream side thereof, and a secondary air introduction hole 11 is provided at a downstream side thereof. Have. A spiral primary air introduction hole 4 is formed in the swirler 3. Reference numeral 7 denotes a flame stabilizer provided at the center of the combustor of the gas turbine, and a combustion air (air-fuel mixture) 5 formed by the primary combustion cylinder 2 and the flame stabilizer 7 of the combustor 1. Are formed up to the combustion chamber 6. The spiral primary air introduction hole 4 is formed from the outer edge opening 4a of the swirler 3 to the flow path 5 on the downstream side thereof,
The primary air A for combustion introduced into the primary inlet 4 from outside the swirler 3 is supplied to the combustion chamber 6 through the primary air inlet 4 and the flow path 5. 12 is a secondary combustion cylinder. A fuel injection nozzle 9 is provided on an abdominal wall 3b near the opening 4a in the primary air introduction hole 4 and having a curved shape in which the blade 3a of the swirler 3 is depressed inward. Reference numeral 10 denotes a screw for mounting the blade. An annular ring 8 having holes drilled at predetermined intervals in the circumferential direction is rotatably fitted on the outer peripheral surface of the circular swirler 3 so as to cover the opening 4 a of the primary air introduction hole 4. .
The holes of the ring 8 are provided in the same number as the number of the openings 4a of the primary air introduction hole 4, have substantially the same area as the openings 4a, and are formed so as to be overlapped with the openings 4a. By rotating the ring 8, the area of the opening 4a can be changed within a predetermined range (0 to all areas),
Thereby, the inflow amount of the primary air A can be controlled.

[Action]

Regarding the premixing of the gas turbine combustor, in order to keep the ratio of fuel and air constant even at a partial load, the ring 8 is rotated through a predetermined rotating mechanism in accordance with the load, so that the primary air introduction hole is formed. The inflow amount of the primary air A can be controlled by changing the area of the opening 4a. As a result, the ratio of air to fuel is always kept constant. Therefore, in the gas turbine combustor having the premixing device of the present invention,
There is no need to install a pilot combustor. Thus, fuel is supplied at all times a proper mixing ratio throughout the operation, flame holding is not required by the pilot fuel, the combustion instability is eliminated, NO _X amount in the exhaust gas is reduced, non燃排gas substances such as CO Is also prevented.

〔Example〕

 Next, the present invention will be described with reference to examples.

FIG. 4 shows the effect on the outlet exhaust gas concentration and the gas temperature when the fuel load is changed. Total air volume Ma = 0.3MPa,
When the total equivalent ratio φ = 0.27, the air temperature at the combustor inlet T ₂ = 573 K is constant, the primary equivalent ratio φ ₁ = 0.75 and the fuel flow rate is changed (white), and the primary air as in the conventional combustion method Quantity ratio
The results are shown in comparison with the case where the fuel flow rate is changed while Ma1 / Ma = 0.35 (black mark).

At full load, both achieve almost the target values of the exhaust gas concentration and the gas temperature, but differ greatly at partial load.
When only the fuel is reduced as in the latter at the time of partial load, the primary equivalent ratio decreases and the combustion becomes inactive due to the cooling action of the excess air, so the NO _X concentration does not increase, but the CO concentration increases significantly, The outlet gas temperature also drops unexpectedly. On the other hand, when the primary air amount is also reduced so that the primary equivalent ratio becomes constant with a decrease in the fuel at the partial load as in the former case, the fuel can be reduced without impairing the combustion in the primary combustion region, NO _X, CO concentration both is within the target value, a decrease in the outlet gas temperature approximately equal to the predetermined value.

〔The invention's effect〕

As described above, according to the present invention, an annular ring provided with holes at predetermined intervals in the circumferential direction is rotatably fitted to the outside of the swirler to change the area of the opening of the primary air introduction hole. The primary air inflow can be controlled with good responsiveness, and the ratio of fuel to air can be kept constant at all times, eliminating combustion instability, enabling low-temperature combustion, and _the amount of NO _X is decreased, non燃排gas was also industrially useful effects such as to be prevented the generation of the CO or the like is provided.

[Brief description of the drawings]

1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a sectional view taken along line AA of FIG. 1, FIG. 3 is a sectional view taken along line BB 'of FIG. 2, and FIG. FIG. 5 is a graph showing the outlet exhaust gas concentration and the effect on the gas concentration when the fuel load is changed. FIG. 5 is a schematic sectional view showing an example of a conventional premixed gas turbine combustor. In the drawings: 1 ... gas turbine combustor 2 ... primary combustion cylinder 3 ... swirler 3a ... blade, 3b ... ventral wall 4 ... primary air introduction hole, 4a ... opening 5 ... flow Road 6, combustion chamber 7, flame holder 8, ring 9, fuel injection nozzle 10, screw for mounting 11, secondary air introduction hole 12, secondary combustion cylinder 13 ... gas turbine combustor 14 ... pilot combustor, 15 ... main combustor 16 ... main fuel injection device 17 ... premixing device 18 ... curved bypass pipe for introducing secondary air 19 ... bypass mechanism A ... … Primary air.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F23R 3/14 F23R 3/30 F23R 3/26 F23R 3/10

Claims (2)

(57) [Claims] 1. A fuel injection system for a swirler having a plurality of primary air introduction holes spirally perforated for giving a swirling motion to combustion air, the blades of the swirler forming the air introduction holes. Providing a nozzle, the installation position of the fuel injection nozzle,
A gas turbine combustion that has an abdominal wall which is an inner peripheral side of the air introduction hole and injects fuel from the fuel injection nozzle toward an air flow passing through the air introduction hole to perform premixing of air and fuel. In the premixing method in the vessel, an annular ring having a hole having substantially the same area as the opening of the primary air introduction hole is provided on the outer peripheral surface of the circular swirler at predetermined intervals in a circumferential direction so as to be rotatable. A method of premixing in a gas turbine combustor, wherein the amount of air flowing into the primary air introduction hole is controlled by changing the opening area of the primary air introduction hole by inserting and rotating the ring. 2. A swirler having a circular shape in which a plurality of air introduction holes for giving a swirling motion to combustion air are spirally formed.
A fuel injection nozzle for injecting fuel into the air introduced into the air introduction hole of the swirler, wherein the fuel injection nozzle is provided at the air introduction hole of the swirler blade forming the air introduction hole. A premixing device in a gas turbine combustor, which is provided on an abdominal wall which is an inner peripheral side of the gas turbine and is capable of injecting fuel toward an air flow passing through the air introduction hole; On the outer peripheral surface, an annular ring provided with holes having substantially the same area as the openings of the primary air introduction holes at predetermined intervals in the circumferential direction for changing the opening area of the primary air introduction holes is rotated. A premixing device for a gas turbine combustor, wherein the mixing device is inserted as possible.