Combustor of gas turbine and combustion control method for gas turbine

Abstract

In a combustor, divisional fluid passages of a first group, and divisional fluid passages of a second group are present on an inner peripheral side, and divisional fluid passages are also present on an outer peripheral side, and swirl air flows are gushed from the divisional fluid passages. When the total amount of fuel supplied to the combustor is small as in a speed increasing state or in a low load state, fuel is injected only into the divisional fluid passages of the first group. Since a fuel injection region is limited to a position on the inner peripheral side, particularly, a specific position, the concentration of a fuel gas comprising a mixture of fuel and air is lean, but is higher than a flammability limit concentration, even when the total amount of fuel is small.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:

FIG. 1 is a longitudinal sectional view showing a combustor according to Embodiment 1 of the present invention;

FIG. 2 is a front view showing the combustor according to the Embodiment 1;

FIG. 3 is a schematic view showing a fuel supply system in the Embodiment 1;

FIGS. 4( a) to 4(e) are characteristic views showing fuel control characteristics in the Embodiment 1;

FIGS. 5( a) and 5(b) are characteristic views showing pressure characteristics and temperature characteristics in the Embodiment 1;

FIG. 6 is a front view showing a combustor according to Embodiment 2 of the present invention;

FIG. 7 is a longitudinal sectional view showing a combustor according to Embodiment 3 of the present invention;

FIGS. 8( a) and 8(b) are characteristic views showing the fuel injection characteristics of the combustor according to the Embodiment 3;

FIGS. 9( a) and 9(b) are perspective views showing essential parts of a combustor according to Embodiment 4 of the present invention;

FIG. 10 is a configurational drawing showing a conventional combustor; and

FIG. 11 is a characteristic view showing the relationship between an equivalence ratio and the amount of NO_x generated.

Claims

1. A combustor of a gas turbine, the combustor comprising an inner tube and a transition pipe connected together, wherein an internal swirler comprising a cylindrical internal swirler ring disposed concentrically with respect to a central axis of the inner tube, and a plurality of internal swirler vanes provided on an outer peripheral surface of the internal swirler ring, andan external swirler comprising a cylindrical external swirler ring disposed on an outer peripheral side of the internal swirler vanes and concentrically with respect to the internal swirler ring, and a plurality of external swirler vanes provided on an outer peripheral surface of the external swirler ringare arranged inside the inner tube to forminternal divisional fluid passages defined by the internal swirler ring, the external swirler ring, and the plurality of the internal swirler vanes, andexternal divisional fluid passages defined by the external swirler ring, the inner tube, and the plurality of the external swirler vanes,the internal divisional fluid passages are divided into a first group consisting of a plurality of the divisional fluid passages arranged sequentially in a circumferential direction, and a second group consisting of a plurality of the divisional fluid passages arranged sequentially in the circumferential direction,a fuel injection hole for injecting fuel into the internal divisional fluid passages is formed in a vane surface of each of the internal swirler vanes, anda fuel injection hole for injecting fuel into the external divisional fluid passages is formed in a vane surface of each of the external swirler vanes, andthe combustor further comprisingfirst fuel supply means for supplying fuel to the fuel injection holes facing the internal divisional fluid passages of the first group among the fuel injection holes formed in the internal swirler vanes,second fuel supply means for supplying fuel to the fuel injection holes facing the internal divisional fluid passages of the second group among the fuel injection holes formed in the internal swirler vanes, andthird fuel supply means for supplying fuel to the fuel injection holes formed in the external swirler vanes.

2. The combustor of a gas turbine according to claim 1, wherein at a rear edge of the inner tube, blocking members for inhibiting outflow of a fluid are disposed in boundary portions between the divisional fluid passages of the first group and the divisional fluid passages of the second group.

3. The combustor of a gas turbine according to claim 1, wherein of the fuel injection holes formed in the internal swirler vanes, the fuel injection holes facing the internal divisional fluid passages, which are among the internal divisional fluid passages of the first group and which are adjacent to the divisional fluid passages of the second group, have larger hole diameters than the hole diameters of the other fuel injection holes.

4. The combustor of a gas turbine according to any one of claims 1 to 3, wherein a rear edge of each of the internal swirler vanes is flattened, and a fuel injection hole for injecting fuel is formed in the rear edge of each of the internal swirler vanes.

5. A combustion control method for a gas turbine, applied to the combustor of a gas turbine according to any one of claims 1 to 3, and comprising: presetting a speed increasing state, and also presetting a low load state, a medium load state, a high load state, and an ultrahigh load state sequentially in accordance with an increase in load;injecting fuel from the first fuel supply means, the fuel being in such an amount as to bring about a lean state, through the fuel injection holes facing the internal divisional fluid passages of the first group in the speed increasing state and in the low load state;injecting fuel from the first fuel supply means, the fuel being in such an amount as to bring about a lean state, through the fuel injection holes facing the internal divisional fluid passages of the first group in the medium load state, and also injecting fuel from the second fuel supply means, the fuel being in such an amount as to bring about a lean state, through the fuel injection holes facing the internal divisional fluid passages of the second group in the medium load state;injecting fuel from the first fuel supply means, the fuel being in such an amount as to bring about a lean state, through the fuel injection holes facing the internal divisional fluid passages of the first group in the high load state, also injecting fuel from the second fuel supply means, the fuel being in such an amount as to bring about a lean state, through the fuel injection holes facing the internal divisional fluid passages of the second group in the high load state, and further injecting fuel from the third fuel supply means, the fuel being in such an amount as to bring about a lean state, through the fuel injection holes facing the external divisional fluid passages in the high load state; andinjecting fuel from the first fuel supply means, the fuel being in such an amount as to bring about a rich state, through the fuel injection holes facing the internal divisional fluid passages of the first group in the ultrahigh load state, also injecting fuel from the second fuel supply means, the fuel being in such an amount as to bring about a rich state, through the fuel injection holes facing the internal divisional fluid passages of the second group in the ultrahigh load state, and further injecting fuel from the third fuel supply means, the fuel being in such an amount as to bring about a lean state, through the fuel injection holes facing the external divisional fluid passages in the ultrahigh load state.