Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – With indicator or control of power plant
Reexamination Certificate
1999-07-06
2001-02-27
Nguyen, Tan (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
With indicator or control of power plant
C060S039370, C060S039465
Reexamination Certificate
active
06195607
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to fuel-air optimization in annular gas turbine combustors and more particularly concerns a system for continual on-line trimming of the fuel flow rate to rings of a annular combustor to optimize NOx emissions.
FIG. 1
shows a gas turbine combustor system
10
from a Dry Low Emissions (DLE) Industrial Engine, such as the GE LM6000™, which includes a compressor
2
, a combustor
3
and a turbine
4
. Fuel is mixed with compressed air from the compressor
2
and burned in the combustor
3
. The resulting flow of combustion products out of the combustor
3
drives the turbine
4
, which in turn drives a load (not shown) as well as the compressor
2
. The exhaust from the turbine
4
is eventually released to the atmosphere. One type of combustor commonly used today is the so-called annular combustor. One exemplary embodiment of the annular combustor comprises a plurality of separate rings, wherein each ring is connected to the compressor
2
and the fuel supply provides combustion products to drive turbine
4
. This combustor is fully described in U.S. Pat. No. 5,323,604.
FIG. 1
further shows one embodiment of a DLE type annular combustor
3
having three rings
5
,
7
, and
9
. The rings define a combustion chamber (not shown) to which a fuel-air mixture from an inner ring premixer
12
, a pilot ring premixer
16
, and an outer ring premixer
18
is injected. Compressed air enters each of the premixers
12
,
16
, and
18
via an air line
13
and fuel enters via a fuel line
15
. A main valve
14
, also referred to as a pilot value, is disposed in the fuel line
15
to throttle the flow of fuel into each of outer ring premixer
12
and inner ring premixer
18
. Alternatively, the fuel and air may be directly injected into the combustion chamber without premixing. This results in near-stoichiometric, high temperature combustion which leads to copious production of varying combinations of oxides of Nitrogen, which are generally referred to as NO
x
. Premixing the fuel and air prior to combustion results in lean premixed combustion, which produces lower flame temperatures and thus lower NO
x
emissions. Flame temperature in a ring of the combustor is proportional to the fuel-air-ratio in the operating region of a DLE type combustor, hence ring flame temperature and fuel-air-ratio are used interchangeably in the present specification.
Reducing emissions of harmful gases such as NO
x
into the atmosphere is of prime concern. It is, therefore, desirable for gas turbine-based power plants burning natural gas to employ means for dramatically reducing NO
x
emissions. Natural gas-fired gas turbines produce no measurable particulate exhaust of oxides of Sulfur (SO
x
) and, if the combustion process is properly controlled, very little NO
x
or Carbon Monoxide (CO).
There is a need for real time, on-line trimming of the fuel flow to each ring of a annular combustor in accordance with minimizing total NO
x
emissions. There is an additional need for a trim system to carry out the real time, on-line trimming which is retrofittable to existing gas turbines. The trim system must be such that its failure will not affect the baseline operation of the gas turbine.
BRIEF DESCRIPTION OF THE INVENTION
The above-mentioned needs are addressed by the present invention which provides apparatus and method for minimizing NO
x
emissions of a gas turbine. The present invention comprises a fuel control system for controlling the ratio of ring temperature adjustment in at least one ring of an annular combustor in a gas turbine. The fuel control system consists of a computer to perform the steps of; 1) defining an operational boundary of inner ring temperature adjustment versus an outer ring temperature adjustment that defines a safe operating region for the gas turbine; 2) calculating a operating point of the inner ring temperature adjustments versus the outer ring temperature adjustment within a safety margin of the operational boundary, wherein NO
x
emission levels of the gas turbine is substantially minimized; and 3) regulating each ring temperature adjustment to maintain a near global minimum point of operation while maintaining normal operating parameters.
REFERENCES:
patent: 4700542 (1987-10-01), Wang
patent: 4910957 (1990-03-01), Moreno et al.
patent: 4928481 (1990-05-01), Joshi et al.
patent: 5309709 (1994-05-01), Cederwall et al.
patent: 5323604 (1994-06-01), Ekstedt et al.
patent: 5365732 (1994-11-01), Correa
patent: 5373692 (1994-12-01), Correa
patent: 5761895 (1998-06-01), Chu et al.
patent: 5850732 (1998-12-01), Willis et al.
Goodman George Charles
Hook Richard Bradford
Joshi Narendra Digamber
Rajamani Ravi
Breedlove Jill M.
General Electric Company
Nguyen Tan
Thompson John F.
LandOfFree
Method and apparatus for optimizing NOx emissions in a gas... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for optimizing NOx emissions in a gas..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for optimizing NOx emissions in a gas... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2580355