Power plants – Combustion products used as motive fluid
Reexamination Certificate
2000-09-27
2002-03-19
Kim, Ted (Department: 3746)
Power plants
Combustion products used as motive fluid
C060S039091, C060S039230
Reexamination Certificate
active
06357216
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to control systems for combustors in gas turbine engines having air bypass systems and in particular to a control system that arrests flashback in such combustors.
BACKGROUND OF THE INVENTION
Lenertz et al. U.S. Pat. No. 6,070,406 entitled “Combustor Dilution Bypass System” discloses a combustor having two combustion systems generally denoted by the letters A and B as shown in FIG.
1
. Each of these systems includes an air bypass system having a valve
12
with an inlet port
16
, and two exit ports
18
and
20
. Inlet port
16
is connected to an inlet duct
17
for receiving compressed air from the combustor plenum
19
that circumscribes the combustion chamber
60
which is defined by a combustor wall
62
. Exit port
18
connects to the premixer duct
22
which leads to the premixer injector
64
that injects tangentially a mixture of fuel and air into the combustion chamber
60
. The injector
64
has a fuel nozzle
66
, a venturi
70
, a premix chamber
68
and an igniter
72
. In operation, the fuel nozzle injects a fuel-air mixture into the premix chamber
68
. In the premix chamber additional air is added through premixer duct
22
. The igniter
72
ignites this mixture during engine starting creating a hot gas
74
that flows into and around the combustion chamber
60
. The second exit port
20
connects to the bypass duct
24
. The valve
12
includes a rotatable valve rotor
26
for selectively controlling the relative proportions of airflow to premixer duct
22
and bypass duct
24
. The position of the rotor
26
is controlled by an electronic unit for the gas turbine engine in which these combustion systems are deployed.
Flashback involves the flame from the combustion chamber
60
being drawn back into the venturi
70
and premix chamber
68
and may be caused by a backflow from the combustion chamber due to compressor instability, transient flows, varying operating conditions and/or varying fuel properties. Because the metals or alloys used to form the venturi and premix chamber cannot withstand high temperatures for significant amount of time, damage can quickly occur to these structures in the presence of a flashback. The flashback can be arrested by increasing the airflow into the venturi and premix chamber.
Accordingly, there is a need for a control and method for increasing air flow to the injector
64
in the event of a flashback.
SUMMARY OF THE INVENTION
An object of the present invention is to provide for a control and method for arresting flashback in a gas turbine engine combustion system having a venturi for delivering a mixture of air and fuel to a combustion chamber and a valve for controlling the amount of air flowing to the venturi.
The present invention achieves this object by providing a flashback control system and method having a flashback detection routine, a valve position trim routine, and a reference flame temperature adjustment routine. The flashback detection routine detects a flashback in the venturi by comparing the temperature at the venturi to the temperature of the air entering the valve. The valve position trim routine receives this flashback signal and in response causes the valve to open until the flashback is arrested. Finally, to prevent the flashback from recurring, the reference flame temperature adjustment routine adjusts a reference flame temperature in the control system so as to prevent the valve from returning to the position at which the flashback occurred.
These and other objects, features and advantages of the present invention, are specifically set forth in, or will become apparent from, the following detailed description of a preferred embodiment of the invention when read in conjunction with the accompanying drawings.
REFERENCES:
patent: 3635018 (1972-01-01), De Corso et al.
patent: 3701137 (1972-10-01), Hulsman
patent: 4094142 (1978-06-01), Pfefferle
patent: 4115998 (1978-09-01), Gilbert et al.
patent: 4122667 (1978-10-01), Hosaka et al.
patent: 4138842 (1979-02-01), Zwick
patent: 4959638 (1990-09-01), Palmer
patent: 5073104 (1991-12-01), Kemlo
patent: 5148667 (1992-09-01), Morey
patent: 5397181 (1995-03-01), McNulty
patent: 5613357 (1997-03-01), Mowill
patent: 5857320 (1999-01-01), Amos et al.
patent: 6070406 (2000-06-01), Lenertz et al.
patent: 6135760 (2000-10-01), Cusack et al.
patent: 6210152 (2001-04-01), Haffner et al.
Anson Bruce S.
Critchley Ian L.
Hernandez Lorenzo
Scott Michael W.
Desmond, Esq. Robert
Honeywell International , Inc.
Kim Ted
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