Power plants – Combustion products used as motive fluid
Reexamination Certificate
1999-02-18
2001-11-27
Freay, Charles G. (Department: 3746)
Power plants
Combustion products used as motive fluid
C060S039190, C060S039550
Reexamination Certificate
active
06321526
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a gas turbine, and in particular, to a gas turbine starting control system capable of increasing starting power while suppressing a rise in inlet gas temperature of the turbine during starting of the gas turbine.
2. Description of the Related Art
FIG. 3
is a block diagram schematically showing a general gas turbine. In
FIG. 3
, reference numeral
1
indicates a compressor for compressing intake gas (air)
2
, reference numeral
5
indicates a turbine coaxially provided with the compressor
1
, and reference numeral
4
indicates a combustor. High-pressure air compressed by the compressor
1
is first delivered through a compressed-air path
13
to the combustor
4
where fuel is injected into the high-pressure air for combustion. As a result, combustion gas is generated. This combustion gas is then delivered to the turbine
5
through a combustion gas path
12
to perform expansion work by acting on moving blades of the turbine.
The gas turbine with the above mentioned arrangement generally exhausts some of the intake gas
2
(air) sucked into the compressor
1
to the outside through an extraction pipe
3
during starting of the gas turbine to prevent a rotating stall of the compressor
1
. Accordingly, since the gas supplied to the turbine
5
through the combustor
4
has a smaller flow rate during starting of the gas turbine, there is a need for auxiliary power to start rotation of the rotational shaft of the compressor
1
and turbine
5
. Consequently, a starting motor
6
is connected to the rotational shaft of the compressor
1
and turbine
5
, and the power of the starting motor
6
is supplied thereto as an auxiliary power for starting the gas turbine.
FIG. 2
illustrates changes in an inlet gas temperature of the turbine with respect to the number of revolutions during starting of the above mentioned gas turbine provided with a starting motor. In the conventional gas turbine, as indicated by line B in
FIG. 2
, the inlet gas temperature of the turbine reaches it's maximum point at about 50% of rated speed and may exceed a predetermined allowable value. Moreover, line A in
FIG. 2
indicates changes in the inlet gas temperature of the turbine with respect to the number of revolutions during starting of a gas turbine in accordance with the present invention, to be described later.
Nevertheless, in conventional gas turbines sufficient cooling air is generally not supplied to the moving blades and the like during starting of the gas turbine. Accordingly, the inlet gas temperature of the turbine must be kept at the above-mentioned allowable value (see
FIG. 2
) or lower. Consequently, in the conventional gas turbines described above, the starting motor
6
must have a large capacity in order to prevent an excess turbine load at the above-described 50% of rated speed. Accordingly, there are problems in that the space required to install such a large, high capacity starting motor is increased which increases the cost of the system as well.
SUMMARY OF THE INVENTION
The present invention has been made to provide a gas turbine starting control system, wherein the starting power is enhanced while the inlet gas temperature of the turbine is restrained from rising during starting of the gas turbine, so that the starting motor can be reduced in size and the system costs can be reduced.
The present invention is intended to solve the foregoing problems and to provide a gas turbine starting control system for a gas turbine in which starting power is supplied to a rotational shaft of a compressor and turbine by using a starting motor in order to start the compressor and the turbine. The gas turbine starting control system comprises a steam pipe for supplying steam to a combustor in the gas turbine; a temperature detector for detecting an inlet gas temperature of the turbine; a steam control valve provided at the steam pipe for opening and closing the steam pipe; and a valve controlling unit for controlling the opening degree of the steam control valve in response to detection signals of the inlet gas temperature from the temperature detector.
In accordance with the above-mentioned structure, the valve controlling unit outputs a release signal to the steam control valve when the inlet gas temperature detected by the temperature detector is above a predetermined allowable value. The steam control valve then opens the steam pipe leading to the combustor in response to the release signals. Thus, steam having a predetermined pressure is delivered to the combustor and then supplied to the turbine together with the gas delivered from the combustor.
With such an arrangement, the turbine can obtain an output increase corresponding to the energy of the steam delivered to the combustor during starting while the inlet gas temperature of the turbine can be kept at a predetermined allowable value or lower. Therefore, according to the present invention, the inlet gas temperature of the turbine can be maintained at a predetermined allowable value or lower, and the gas turbine can be safely started up with a large starting power supplemented by the energy of the steam.
REFERENCES:
patent: 4350008 (1982-09-01), Zickwolf, Jr.
patent: 5101619 (1992-04-01), Morris et al.
patent: 5121596 (1992-06-01), Takehara et al.
patent: 5241817 (1993-09-01), George, Jr.
patent: 5315816 (1994-05-01), Kemmer et al.
patent: 10-8999 (1998-01-01), None
Freay Charles G.
Mitsubishi Heavy Industries Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
LandOfFree
Gas turbine starting control system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Gas turbine starting control system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Gas turbine starting control system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2618334