Combustion – Separately supplied or controlled – physically related flame... – Having common flame chamber or shield means
Reexamination Certificate
1999-04-12
2001-07-31
Price, Carl D. (Department: 3743)
Combustion
Separately supplied or controlled, physically related flame...
Having common flame chamber or shield means
C431S009000, C431S278000
Reexamination Certificate
active
06267583
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a combustor and more specifically to a combustor which is appropriate for use as a gas turbine combustor.
2. Description of the Prior Art
One example of a premixed flame type combustor which is used as a prior art gas turbine low NOx type combustor is shown in
FIG. 13
, wherein FIG.
13
(
a
) is a longitudinal cross sectional view of the combustor and FIG.
13
(
b
) is a cross sectional view taken on line C—C of FIG.
13
(
a
).
In
FIG. 13
, within a combustor
201
which is provided for a gas turbine cylinder, there are provided a plurality (eight pieces in this case) of main burners
202
around a central axis of the combustor
201
. Each of the main burners
202
comprises therein a main fuel nozzle
203
of the same shape for all the main burners
202
, and a main swirler
204
of also the same shape. Also, provided in a portion surrounded by the plurality of main burners
202
and along the central axis of the combustor
201
is a pilot burner
207
, which comprises therein a pilot fuel nozzle
206
and a pilot swirler
205
provided around the pilot fuel nozzle
206
.
Combustion air flowing inside of an outer periphery of the combustor
201
turns at an angle of 180° at an air inflow portion
208
to flow in the combustor
201
passing through the main swirler
204
of each of the main burners
202
and the pilot swirler
205
of the pilot burner
207
.
In the pilot burner
205
, pilot fuel supplied from the pilot fuel nozzle
206
is burned by the combustion air which has passed through the pilot swirler
205
. In the main burner
202
, main fuel supplied from the main fuel nozzle
203
and the combustion air which has passed through the main swirler
204
are mixed to form a premixture, which is fired by a pilot flame of the pilot fuel so that a low NOx combustion is effected in the combustor
201
.
The premixture formed in the main burner
202
is fired by the pilot flame of the pilot fuel, as mentioned above. In this case, as there is substantially a regularity in a mixing state of the premixture between each of the plurality of main burners
202
, the combustion state in each of the main burners
202
becomes regular. This results in a regularity in heat generation distribution throughout the combustor
201
along the central axis direction thereof, and there occurs a constant area where a large heat generation in the combustor
201
is concentrated.
For this reason, vibratory combustion is prone to occur due to such concentrated heat generation to cause a non-stability of the combustion, which results in a problem in that a low NOx combustion is hampered.
FIG. 14
is a cross sectional view showing one example of a prior art pilot nozzle of gas turbine. In
FIG. 14
, numeral
301
designates a nozzle body and numeral
302
designates an air passage in a peripheral portion of the nozzle body
301
, into which air
311
is taken. Numeral
303
designates an oil fuel supply pipe which is provided in a central portion of the nozzle body
301
for leading therethrough an oil fuel
310
. Numeral
304
designates a gas fuel passage for leading therethrough a gas fuel
312
when such is used. Numeral
305
designates an oil fuel injection port, numeral
306
designates an air injection port and numeral
307
designates a gas fuel injection port. In the nozzle so constructed, both the oil fuel
310
and the gas fuel
312
are usable wherein the fuel is injected from a tip end of the nozzle and the air
311
for diffusion and water
309
for cooling are injected as described later so that combustion is effected.
FIG. 15
is an enlarged cross sectional view of a tip end portion of the pilot nozzle of FIG.
14
. In
FIG. 15
, when an oil fuel is used, the oil fuel
310
is supplied through the oil fuel supply pipe
303
to be injected for combustion into a combustion chamber from the oil fuel injection port
305
of the central portion. On the other hand, the air
311
flows through the air passage
302
in the peripheral portion of the nozzle body
301
to be injected from the air injection port
306
for diffusion of the fuel. Also, the water
309
is injected from a water injection port
308
provided around the oil fuel injection port
305
to cool a peripheral portion of the oil fuel injection port
305
.
In the above-mentioned pilot nozzle, the oil fuel
310
injected from the oil fuel injection port
305
spreads into the surrounding area, as shown in FIG.
15
. On the other hand, the air
311
is injected from the air injection port
306
at such an angle as to cross the oil fuel
310
so spreading, thus there is formed therebetween a stagnation area
320
into which neither the air
311
nor the oil fuel
310
comes. But a mist
321
is formed by a portion of the oil fuel
310
scattering there, and this mist flows into this stagnation area
320
and sticks to the tip end of the nozzle to accumulate there as an unburnt carbon
322
. This unburnt carbon
322
increases gradually so that the water injection port
308
may be plugged and the flow of the air
311
from the air injection port
306
may be obstructed. As a result, there arises a problem in that the cooling performance of the peripheral portion of the oil fuel injection port
305
is deteriorated or the combustion performance is badly affected.
In case the oil fuel is used in the prior art gas turbine pilot nozzle, as mentioned above, the stagnation area
320
is formed between the oil fuel injection port
305
and the air injection port
306
and the mist
321
of the oil fuel
310
scatters and sticks to the tip end of the nozzle to accumulate while being carbonized as the unburnt carbon
322
. This results in plugging of the water injection port
308
to obstruct the injection of the water which causes a problem affecting the nozzle performance such that the cooling performance of the peripheral portion of the oil fuel injection port
305
is deteriorated or the flow of the injected air is obstructed.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a combustor which is able to dissolve shortcomings in the prior art combustor as shown in
FIG. 13
, in which a vibratory combustion due to a concentrated heat generation easily occurs resulting in an unstable combustion.
It is also an object of the present invention to provide a low NOx combustor in which there is formed a heat generation distribution that is averaged more in an axial direction of the combustor so that a heat generation may be less concentrated on a constant area, a stable combustion may be attained with less vibratory combustion, and so that a low NOx combustion may not be hampered.
It is a further object of the present invention to, provide a combustor which is able to solve shortcomings in the prior art combustor as shown in
FIGS. 14
,
15
in which an unburnt carbon sticking to and accumulating on a stagnation area is formed.
In order to attain the object of not causing a vibratory combustion, the present invention provides a combustor comprising a pilot fuel nozzle unit having therein a plurality of pilot fuel nozzles and a plurality of main premixing nozzle units disposed on a coaxial circumference surrounding the pilot fuel nozzle unit for mixing fuel supplied from a main fuel nozzle of the respective main premixing nozzle units with air to form a premixture. The plurality of pilot fuel nozzles are arranged irregularly in a circumferential direction of the pilot fuel nozzle unit.
In the combustor constructed so that the pilot fuel nozzles are arranged irregularly in a circumferential direction of the pilot fuel nozzle unit, the pilot fuel nozzles do not necessarily correspond to the main premixing nozzles one to one.
While the premixture coming from the main premixing nozzle which is positioned to correspond to the pilot fuel nozzle generates combustion with short flames, the premixture coming from the main premixing nozzle which is in a position where there is no corresponding pilot fuel nozzle gener
Akita Eiji
Mandai Shigemi
Nishida Koichi
Ota Masataka
Mistubishi Heavy Industries, Ltd.
Price Carl D.
Wenderoth , Lind & Ponack, L.L.P.
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-2511749