Power plants – Combustion products used as motive fluid – With addition of steam and/or water
Reexamination Certificate
2001-11-15
2003-12-16
Koczo, Michael (Department: 3746)
Power plants
Combustion products used as motive fluid
With addition of steam and/or water
C239S424000
Reexamination Certificate
active
06662547
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a combustor. More specifically, the present invention relates to a combustor, such as a gas turbine combustor, which transfers a combustion gas from a burner to a combustion chamber and actuates a turbine by using the combustion gas.
2. Description of Related Art
In general, a gas turbine includes a compressor, a combustor, and a turbine as its main constituents, and the compressor and the turbine are directly connected to each other by a main shaft. The combustor is connected to a discharge opening of the compressor, and a working fluid discharged from the compressor is heated to predetermined turbine inlet temperature by the combustor. The working fluid of high temperature and high pressure supplied to the turbine passes between a stationary blade and a moving blade, which is attached to the main shaft side, and expands. In this manner, the main shaft is rotated and an output is obtained. For the case where a gas turbine is used, since a brake power from which power consumed by a compressor is subtracted is obtained, it may be used as a good driving source by connecting a generator, etc., to the other end of the main shaft.
A schematic structure of a gas turbine combustor will be explained as follows by using an oil firing combustor as an example.
In
FIG. 10
, the numeral
10
indicates an oil firing combustor. In the combustor
10
, a premix nozzle
12
is provided along the central axis of a heat chamber
11
. A pilot burner
13
is disposed at the center portion of the premix nozzle
12
, and a plurality of main burners
1
are disposed with an equal interval between each other so as to surround the pilot burner
13
. Accordingly, the central axis of the pilot burner
13
coincides with the central axis of the heat chamber
11
.
Fuel is supplied to the pilot burner
13
via a pilot fuel pipe
14
, and a pilot fuel discharged from a pilot fuel nozzle
14
a
, which is disposed at an end portion of the pilot burner
13
, is combusted in a combustion chamber
10
a
in the heat chamber
11
using a swirling air flow as combusible air. The flame of the pilot burner
13
thus generated is used as an ignition source for a main burner
1
which will be described below.
Each of the main burners
1
for the premix nozzle
12
includes a main fuel supply duct
2
, which is connected to a fuel supply source not shown in the figure, and a main swirler
5
, which swirls an air flow passing through an outer periphery portion of the main fuel supply duct
2
.
The main burner
1
discharges the fuel, which is introduced via the main fuel supply duct
2
, from a fuel discharge outlet so that a premixed gas may be produced by premixing the fuel with the air flow. The premixed gas is discharged from each of the main burners
1
and flows around the pilot burner
13
as a swirling flow. The premixed gas is ignited by the above-mentioned flame of the pilot burner
13
used as the flaming source.
Also, the heat chamber
11
, which forms the combustion chamber
10
a
of the combustor
10
, has a structure in which a plurality of rings
15
are coupled, each of the rings
15
being formed by plate fins having a passage for introducing air at the outer periphery side into the inside along the inner surface as cooling air. A combustion process is carried out in the combustion chamber
10
a
, which is formed by the plurality of rings
15
, and the generated combustion gas is transferred to a downstream side as a swirling flow to actuates a turbine, etc.
In the figure, the rings
15
forming the heat chamber
11
includes a first ring
15
a
, a second ring
15
b
, and a third ring
15
c
in order from the premix nozzle
12
.
In the gas turbine having the above-mentioned combustor
10
, when the output thereof is increased, an amount of the fuel supplied is also increased. In such a case, the temperature of the combustion chamber
10
a
is also increased due to the combustion of the larger amount of the fuel. For this reason, spraying a cooling water into the combustion chamber
10
a
is conventionally carried out in accordance with the amount of fuel supplied in order to control the temperature of the combustion gas, which is transferred to the turbine located at the downstream side, and increase the output thereof.
That is, the output of a gas turbine is determined by the turbine inlet temperature and the amount of gas supplied. Thus, when an output larger than possible at the temperature at that time is required, for instance, in summer, the amount of fuel supplied is increased. However, since the allowable temperature for a combustor or a turbine is already determined, the turbine inlet temperature is decreased to a design temperature by supplying water or water vapor into the air. In other words, the temperature of a combustion gas is decreased by increasing an amount of gas by water or water vapor injection so as to maintain a constant temperature, and the output is increased by supplying a large amount of fuel.
As mentioned above, although in the above-mentioned combustor
10
, the temperature of the combustion gas transferred to the turbine is controlled by introducing the cooling water into the combustion chamber
10
a
in order to increase the output of the turbine, the temperature of the rings
15
forming the heat chamber
11
becomes high, particularly in case of an oil firing combustor, due to, for instance, the difference in the vaporizing rate between the fuel and the cooling water.
That is, for instance, in a low NO
x
combustor for a 1400° C.-level gas turbine, the ratio of air used for combustion is high in order to decrease a main flame temperature to achieve a low NO
x
level. For this reason, it is necessary to cool down the surfaces thereof using a very small amount of air, for instance, only about 3.5%. Although the temperature of the surfaces may be decreased to an allowable temperature using such a low amount of cooling air if a gaseous fuel is used, the temperature of the surfaces is increased when the load of the gas turbine exceeds a certain level, if a liquid fuel is used due to an insufficient uniformity between the air and the fuel, a high radiation, etc., and the life of the turbine is shortened. This is because when a liquid fuel is used, a mixing state of the fuel which is the same level as that of a liquid fuel cannot be obtained because of its large density which increases penetration and the wide range of particle size distribution when sprayed.
Accordingly, it is insufficient to carry out a cooling process using only a film cooling or a convection cooling, and there is a danger that the temperature will be drastically increased, particularly for the second ring
15
b
and the third ring
15
c
forming the downstream section of the heat chamber
11
.
SUMMARY OF THE INVENTION
The present invention takes into consideration the above-mentioned circumstances, and has as an object providing a combustor which is capable of preventing heat from damaging a heat chamber of a combustor while enabling to increase an output thereof.
In order to achieve the above object, the present invention provides a combustor, including: a burner; and a combustion chamber including a heat chamber to which fuel is supplied from the burner, wherein the burner includes a nozzle having a fuel discharge outlet from which the fuel is discharged into the combustion chamber; and the nozzle includes a plurality of discharge openings around the fuel discharge outlet, from which cooling water is discharged toward inside surfaces of the heat chamber.
In accordance with another aspect of the invention, the fuel discharge outlet is formed at the center of the nozzle.
According to the above combustor, since the cooling water is discharged from the discharge openings disposed around the fuel discharge outlet which is formed at the center of the nozzle and the cooling water is sprayed onto the inside surfaces of the heat chamber, it becomes possible to reliably cool down the heat chamber.
For this reason, the heat damag
Mandai Shigemi
Nishida Koichi
Ohta Masataka
Tanaka Katsunori
Tanimura Satoshi
Koczo Michael
Mitsubishi Heavy Industries Ltd.
LandOfFree
Combustor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Combustor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Combustor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3099488