Gas: heating and illuminating – Generators – Cupola
Reexamination Certificate
1999-08-26
2004-11-30
Doroshenk, Alexa (Department: 1764)
Gas: heating and illuminating
Generators
Cupola
C048S1970FM, C060S039120, C060S039181, C060S039182, C060S039340, C060S039350
Reexamination Certificate
active
06824575
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an Integrated Coal Gasification Combined Cycle Power Generator (hereinafter referred as IGCC.)
DESCRIPTION OF THE RELATED ART
Reducing the amount of the fossil fuel used and improving system heat efficiency is desired in the latest steam-generated power-generator systems.
Coal, the fossil fuel used for steam-generated power-generator systems, is available in abundant amounts compared to petroleum or natural gas. Consequently, coal is cheaper than petroleum or natural gas. However, although long-term, stable supply is possible, coal burning results in the discharge of environmental pollutants, such as CO
2
and SO
x
. For the above-mentioned reason, use of petroleum or the comparatively clean fuel from natural gas occupies the mainstream.
However, the danger of excessive dependence on petroleum as a source of energy was pointed out by the petroleum crisis of the 1970s.
Moreover, the estimated depletion years of a petroleum and a natural gas, quoting from “Comprehensive Energy Statistics of the Energy Agency, 1991”, will be just 50 years. Considering this fact, long-term stable price and supply of a clean fuel, such as these fuels, is becoming hard.
Consequently, the practical re-use of coal fuel gas to a thermoelectric power system is being recognized once again considering that the possible depletion years will be more than about 300 years based on the estimated amount of coal deposits.
The IGCC which uses a coal-gasification syngas fuel, reduces environmental pollution by generating less CO
2
, SO
x
, NO
x
. Referring to
FIG. 16
, a conventional system of the IGCC is explained.
As shown in
FIG. 16
, the IGCC constitutes a coal-gasification system (
1
), a gas-turbine system (
2
), an exhaust heat recovery boiler (
3
), and a steam turbine system (
4
).
In addition, the exhaust heat recovery boiler can be substituted for a heat recovery steam generator.
The coal-gasification system
1
is provided with a coal supply portion
5
, an oxygen system
6
, and a coal-gasifier
7
.
That is, a pulverized coal from the coal supply portion
5
and an oxygen gas from the oxygen system
6
are supplied to the coal gasifier
7
, and a part of the pulverized coal is burned in the coal gasifier
7
.
The remaining pulverized coal reacts according to the following formula, keeping the temperature above the melting point of coal ashes, in the range of about 1500 degrees C. to about 1800 degrees C.
A combustible coal gas which is composed of carbon monoxide (CO) as a major ingredient is refined as a result of this reaction.
CO
2
+C=2CO.
The oxygen system
6
is provided with an air-compressor
9
driven by a motor
8
.
That is, after the air-compressor
9
compresses an inhaled air, producing a high-pressure air, the air-compressor
9
separates the high-pressure air into an oxygen gas and a nitrogen gas.
After separation from the high-pressure air, the oxygen gas is supplied to a coal gasifier
7
. The air-compressor
9
makes the oxygen gas so-called oxygen blown gas and combustible coal gas is refined in the coal gasifier as mentioned above. After separation, the nitrogen gas is supplied to the gas-turbine system
2
.
Moreover, the coal-gasification system
1
is provided with a cooler
10
and a gas clean-up unit
11
.
A combustible coal gas refined in the coal gasifier
7
is cooled to about 400 degrees C. in the cooler
10
. Then, the combustible coal gas is supplied to the gas-turbine system
2
as the clean coal gasification syngas fuel, after the removal of impurities, such as sulfur and dust, by the gas clean-up unit
11
.
In addition, the cooler
10
cools the combustible coal gas by using cooling water from the steam turbine system
4
. Since the cooling water is recovered again in the steam turbine system
4
, the effective practical use of heat can be attained.
The gas-turbine system
2
is provided an with air-compressor
12
, a gas turbine combustor
13
, a gas turbine
14
and an alternator
15
.
The air-compressor
12
supplies high-pressure air to the gas turbine combustor
13
which is combined with nitrogen gas from the oxygen system
6
and clean coal-gasification gas from the gas cleanup unit
11
.
While the gas turbine combustor
13
dilutes the coal gasification syngas fuel with the nitrogen gas, an expansion work is performed in the gas turbine
14
by using the combustible gas.
An alternator
15
is driven by the driving torque generated by the expansion work. Moreover, the combustible gas which completed the expansion work in the gas turbine
14
is supplied to the exhaust heat recovery boiler
3
as an exhaust gas.
The exhaust heat recovery boiler
3
include a heat exchanger (
16
), which constitutes a super heater, an evaporator and an economizer. Moreover, the exhaust heat recovery boiler
3
uses the exhaust gas supplied from the gas turbine
14
in the gas-turbine system
2
as a heat source. That is, in the exhaust heat recovery boiler
3
, a condensate/feed-water supplied from the steam turbine system
4
performs heat exchange in the heat exchanger
16
, as a result, steam generated in the heat exchanger
16
is supplied to the steam turbine system
4
.
The steam turbine system
4
is provided with a steam turbine
17
, an alternator
18
, a condenser
19
and a feed-water pump
20
. The turbine working steam is made from the steam generated in the exhaust heat recovery boiler
3
and the steam from the cooler
10
in the coal-gasification system
1
. Further, the turbine working steam supplied to the steam turbine
17
drives the alternator
18
by the driving torque generated through performing expansion work.
After performing the expansion work, the turbine working steam (an exhaust gas) is condensed to be used as the condensate/feed-water in the condenser
19
. A part of the condensate/feed-water is supplied to the cooler
10
through the feed-water pump
20
, then, the remainder of the condensate/feed-water flows back to the exhaust heat recovery boiler
3
.
Thus, the IGCC, consisting of the coal-gasification system
1
, the gas-turbine system
2
, the exhaust heat recovery boiler
3
and the steam turbine system
4
, uses the clean and refined coal gasification syngas fuel from the coal gasification system
1
as the gas-turbine working gas. In so doing, the IGCC improves system thermal efficiency and produces low No
x
emissions by combining the “Brayton Cycle” of the gas-turbine system
2
and the “Rankine Cycle” of the steam turbine system
4
.
Although the conventional IGCC shown in
FIG. 16
uses the coal gasification syngas fuel, a clean fuel, and produces an NO
x
concentration within regulatory limits, there are some problems.
One of the problems is related to the improvement in the system thermal efficiency.
In the IGCC, if the gas turbine
14
has a gas-turbine working gas temperature of 1300 degree-C. class, the system thermal efficiency is increased by more than 40%, according to “Outline of New Energy Conversion Technologies: The Heat Transfer Society of Japan, 1996”.
Elevating the system thermal efficiency by more than 40% is dependent on a cooling technology applied to a high-temperature section of the gas-turbine combustor
13
and a high-temperature section of the gas-turbine
14
, such as a liner of the combustor, a gas-turbine nozzle blade, gas-turbine rotor blade and a gas turbine rotor.
As is generally known, in this kind of a system, the higher a gas-turbine working gas temperature rises, the more the system thermal efficiency improves.
However, a super alloys applied to a high-temperature section of the gas-turbine system has as a characteristic an allowable temperature of at most 900 degree C. For this reason, to keep the strength of the high-temperature section within the allowable temperature on the condition that the gas-turbine working gas temperature is made to be high temperature, the gas-turbine nozzle blade and the gas-turbine rotor blade should be cooled as described below.
For example, a part of a high-pressure air generated in the air compressor
1
Aburatani Yoshihiro
Fukuyama Yoshitake
Iijima Hiromitsu
Otomo Fumio
Uchida Tatsuro
Doroshenk Alexa
Foley & Lardner LLP
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