JPS58106327A - Low calorie gas burning gas turbine combustor - Google Patents

Abstract

PURPOSE:To obtain stable combustion in a combustor having inner and outer cylinders by providing a fuel inward swirler of a diameter larger than that of an air swirler provided at the closed end of the inner cylinder at the downstream of the air swirler, thereby suppressing the variation in the excess air ratio of the head of the combustor over a wide load range. CONSTITUTION:Air compressed by a compressor is flowed between the inner cylinder 9 and the outer cylinder 11 of a combustor, is partly supplied from an air swirler 12 into the cylinder 9, is mixed with fuel from a fuel nozzle 10 and is burnt. In a gas turbine combustor thus constructed, a fuel inward swirler 21 of diameter larger than that of an air swirler 12 is provided at the downstream side of the swirler 12. Fuel and air can be preferably mixed by the swirler 21, and combustion intermediate product is burnt by the air from the secondary air hole 14 formed at the downstream. Further, diluted air hole 15 is formed at the downstream of the hole 14, thereby equalizing the combustor outlet gas temperature distribution.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas turbine combustor intended for low-calorie gas fuels such as coal gasified fuel and blast furnace gas.

The basic configuration of a gas turbine is as shown in Fig. 1. Air pressurized by a compressor 1 is sent to a combustor 2, supplied from a pipe 6, and fuel whose flow rate is controlled by a control valve 7 is sent to the combustor 2. The generated high-temperature, high-pressure gas generates power in a turbine 3, and a generator 4 generates electricity.

When natural gas with a high calorific value is used as fuel, the fuel flow rate is small and the adiabatic fire temperature is 20,001 T or more, making it easy to burn in a round shape.As shown in Figure tln2, a radial fuel injection port 16 is provided at the tip of the fuel nozzle 10. % 209 m7
' Inject at a high speed of about 8 and air swirler 12, - next! 2
! The flame is mixed with air from the pores 13 and combusted, and the flame is stabilized by the air flow 19 from the air swirler.

On the other hand, when coal gasified fuel is used, the lower heating value is 90θ~3000 kcal/Nm', which is significantly smaller than the 8000 kcal/Nm' of natural gas, especially when air is used as the oxidizer for coal. If 900-1
500 kC8/-/Nm", which is the lowest in order to obtain turbine inlet gas under the same conditions, requires approximately 10 times more fuel than natural gas. The theoretical amount of air for combustion of this low-calorie gas is approximately the same as that of the fuel. The amount of air changes from 4 to 5 times depending on the operating range of the gas turbine or the fuel-air ratio, so if you decide on the amount of air from the air swirler, taking into consideration flame stability at low loads, you can determine the fuel flow rate at rated load. The ratio between the amount of air and the amount of air from the air swirler is 2 or more, and since air is mixed in the fuel, it is important to promote the mixing of fuel and air in order to improve combustion performance. This ninth conventional method is shown in Fig. 3, in which air and fuel are swirled and mixed at the tip of the fuel/spool 10, and after t, they are swirled in the axial direction of the inner cylinder 9 and supplied. The mixture of air and fuel is relatively good, but because the injection port for the mixture is oriented in the axial direction of the cylinder, the outer diameter of the injection port is limited by the flow butter/forming force that has a large effect on flame holding performance. When the n1 injection nozzle area is small, the fuel injection speed becomes large, and combustion becomes unstable with low-calorie gases that have a slow combustion speed.
It has the disadvantage of reduced blowout performance.

An object of the present invention is to provide a combustor that can stably and efficiently burn a low-calorie gas fuel that has a low combustion speed and is difficult to burn efficiently over a wide operating range of a gas turbine.

In order to achieve stable combustion of low-calorie gas fuel, which is difficult to burn stably, over a wide operating range of the gas turbine, a mixture of fuel and air is formed in a short period of time, and combustion is performed in a state as close to the stoichiometric mixture as possible. It is important to keep the cylinder axial velocity of the fuel low. Accordingly, the present invention promotes mixing by giving a swirl to a large volume of fuel when mixing fuel and air, and creating an angle at which it intersects with the air. This is used to supply primary air into this circulating flow to bring the mixture S* closer to the stoichiometric mixture, and when the combustion load rate is low, the air from the air swirler alone is used to bring the mixture S* closer to the stoichiometric mixture for stable combustion. It was designed to measure the Further, in order to reduce the fuel injection speed in the axial direction of the inner cylinder, the fuel injection port is an inward swirler.

An embodiment of the present invention will be explained below with reference to FIG.

In the gas turbine combustor, air compressed by a compressor between the combustor outer cylinder 11 and the inner cylinder 9 -b! A part of at'L s is supplied into the cylinder from the air swirler 12, and the air swirler area downstream of it is also supplied to the inward swirler 2 for fuel with a large diameter.
Fuel is supplied from the primary air hole 13, partially mixed with air, and then mixed with air from the primary air hole 13 and combusted in a larger diameter melting chamber downstream of the fuel. The air from the secondary air hole 14 located downstream burns the combustion intermediate products, and further downstream there is provided a dilution air hole Ill for making the temperature distribution of the combustor outlet gas uniform. , The overall excess air ratio of the combustor for low calorie gas is almost the same as that of the combustor for natural gas, and the passage area of the air swirler is 5 to 10% of the area of the cylindrical air hole. . This air is 4il! ! ＠There is almost no change in the load factor, and the flame is rotated to maintain flame stability. On the other hand, low calorie gas has a volume ratio with air of 30% or more even in the current combustion notification log gas temperature III 100r class combustor, and LJh also changes by about 5 times depending on the combustion load. Therefore, the fuel injection port is moved to the inward swirler 2 as shown in Fig. 5.
1, the inner diameter of the air swirler 12 is made larger than the outer diameter of the air swirler 12 to lower the fuel velocity in the axial direction of the cylinder when the fuel flow rate is high, improve flame stability, and improve circulation when the combustion load changes. The size is divided into the air swirler 12 main body and the fuel swirler 21 body, and only in the case where the fuel swirler main body has a large fuel flow rate, -
The primary air hole is provided at the wake of the fuel swirler, which is 0.5 to 1.5 times the diameter of the fuel swirler, so that the air from the secondary air hole is supplied to the circulation flow, and a large amount of fuel swirl is provided. A scoop is used to improve air penetration against the flow. The combustion chamber downstream of the fuel swirler has a reduced cross-sectional flow velocity for stable combustion, and a larger diameter to increase residence time and increase combustion efficiency.

As shown in Fig. 5, the swirl angle 20 of the fuel swirler is set to 55 mm or less as a limit that allows the fuel injection flow 18 to intersect with the air swirl flow 19 to promote mixing of the solvent air and to ensure the area of the fuel injection port. 11! I decide.

As a result, there is little change in the excess air ratio at the combustor head from low to high loads, and the axial flow velocity of the fuel is low, making stable combustion possible.

According to the present invention, over a wide operating range from low load to rated load, the gas turbine has little change in excess air ratio at the combustor head, good mixing of fuel and air, and low axial flow velocity of fuel. Therefore, stable combustion can be obtained over a wide range.
Ru.

[Brief explanation of drawings]

Fig. 1 is a basic configuration diagram of a gas turbine, Fig. 2 is a sectional view of a natural gas sinter, Fig. 3 is a sectional view of a conventional low-calorie gas culprit, and Fig. 4 is a sectional view of a combustor of the present invention. Cross-sectional view, Figure 5F
It is a ^-A cross-sectional view of the i-4th factor. 9...Inner cylinder, 10...Fuel nozzle, 12...Air swirler, 13...Next air hole, 16...Fuel injection port, 18...Fuel flow, 19... Air flow n120...
・Turning angle, 21...$ 2 Figure

Claims (1)

[Claims] 1. A hollow cylinder with -J closed and the other end open, an outer cylinder for forming an air passage outside the cylinder, and an inner cylinder for supplying fuel to the closed end side. In a gas turbine combustor consisting of a fuel nozzle of
A primary air hole is provided in the combustion chamber with a larger diameter than the internal swirler for fuel, and a secondary air hole is provided downstream of the combustion chamber.
A gas turbine combustor characterized by having a dilution air hole. 2. A gas turbine combustor according to claim wJ1, characterized in that the inward swirler for fuel is provided at an angle of 55 degrees or less with respect to the radiation from the center and intersects with the swirling air flow. 3. Place the second air scoop on the inside diameter of the inward swirler for fuel.
The gas turbine combustor according to claim 1, wherein the gas turbine combustor is provided downstream of the inward swirler for fuel at a distance of 5 to 1.5 times. 4.% Permissible A gas turbine combustor according to claim 1, characterized in that a scoop is provided in the primary air hole.