U.S. patent application number 09/887459 was filed with the patent office on 2001-10-18 for combustion control method and system.
This patent application is currently assigned to Capstone Turbine Corporation. Invention is credited to Gilbreth, Mark G., Wacknov, Joel B., Wall, Simon R..
Application Number | 20010030425 09/887459 |
Document ID | / |
Family ID | 23825888 |
Filed Date | 2001-10-18 |
United States Patent
Application |
20010030425 |
Kind Code |
A1 |
Gilbreth, Mark G. ; et
al. |
October 18, 2001 |
Combustion control method and system
Abstract
A multi-injector combustion system in which a brake resistor is
utilized to provide a minimum load for the combustor system during
idle or low power operation of the permanent magnet
turbogenerator/motor and also to absorb power during transients to
prevent flame out of the combustor. In addition, during single
injector operation, a relighting method and system are provided to
relight the combustor and prevent the necessity of a complete
shutdown of the system. The method and system includes switching
between the multiple injectors to find the most stable injector in
single injector operation.
Inventors: |
Gilbreth, Mark G.; (Woodland
Hills, CA) ; Wall, Simon R.; (Thousand Oaks, CA)
; Wacknov, Joel B.; (Thousand Oaks, CA) |
Correspondence
Address: |
Rachele Wittwer
IRELL & MANELLA LLP
Suite 900
1800 Avenue of the Stars
Los Angeles
CA
90067
US
|
Assignee: |
Capstone Turbine
Corporation
|
Family ID: |
23825888 |
Appl. No.: |
09/887459 |
Filed: |
June 21, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09887459 |
Jun 21, 2001 |
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09459719 |
Dec 13, 1999 |
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6274945 |
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Current U.S.
Class: |
290/52 |
Current CPC
Class: |
F02C 6/14 20130101; F01D
15/10 20130101; F02C 7/262 20130101; F05D 2220/32 20130101; H02P
9/30 20130101 |
Class at
Publication: |
290/52 |
International
Class: |
F02C 006/00; H02K
007/18; H02P 009/04 |
Claims
What we claim is:
1. A method of relighting a multi injector combustor in a
turbogenerator, the method comprising: a. determining that the
combustor is operating on a single injector considered the primary
injector; b. determining that combustion has ceased; c. turning on
the ignitor; d. determining that the combustor has been relit; e.
switching the primary injector to the next sequential injector: f.
turning off the spark exciter; and g. continuing operation with the
new primary injector.
2. A method of relighting a multi injector combustor in a
turbogenerator, the method comprising: a. determining that the
combustor is operating on a single injector considered the primary
injector; b. determining that combustion has ceased; c. turning on
the ignitor; d. determining that the combustor has been relit; e.
switching the primary injector to the next sequential injector: f.
turning off the spark exciter; g. determining that relight has
occurred; and h. continuing operation with the new primary
injector.
3. A method of relighting a multi injector combustor in a
turbogenerator, the method comprising: a. determining that the
combustor is operating on a single injector considered the primary
injector; b. determining that combustion has ceased; c. turning on
the ignitor; d. determining that the combustor has been relit; e.
switching the primary injector to the next sequential injector: f.
turning off the spark exciter; g. determining that relight has not
occurred; h. repeating steps (a) through (f) until it is determined
that relight has occurred with a stable primary injector; and i.
continuing operation with the new primary injector.
4. A method of relighting a multi injector combustor in a
turbogenerator, the method comprising: a. determining that the
combustor is operating on a single injector considered the primary
injector; b. determining that combustion has ceased; c. determining
that the relight timer has expired; d. turning on the spark
exciter; e. turning on the fuel injector delivering fuel to the
spark exciter area of the combustor; f. turning on fuel delivery to
the then primary fuel injector if the then primary injector is not
the injector delivering fuel to the spark exciter area of the
combustor; g. determining that the combustor has been relit; h.
switching the primary injector to the next sequential injector: i.
turning off the spark exciter; j. turning off the fuel injector
delivering fuel to the spark exciter area of the combustor if that
injector is not the new primary injector; k. resetting the relight
timer; l. determining that relight has occurred; and m. resetting
the relight timer and continuing operation with the new primary
injector.
5. A method of relighting a multi injector combustor in a
turbogenerator, the method comprising: a. determining that the
combustor is operating on a single injector considered the primary
injector; b. determining that combustion has ceased; c. determining
that the relight timer has expired; d. turning on the spark
exciter; e. turning on the fuel injector delivering fuel to the
spark exciter area of the combustor; f. turning on fuel delivery to
the then primary fuel injector if the then primary injector is not
the injector delivering fuel to the spark exciter area of the
combustor; g. determining that the combustor has been relit; h.
switching the primary injector to the next sequential injector: i.
turning off the spark exciter; j. turning off the fuel injector
delivering fuel to the spark exciter area of the combustor if that
injector is not the new primary injector; k. resetting the relight
timer; l. determining that relight has not occurred; m. resetting
the relight timer; n. repeating steps (a) through (k) until it is
determined that relight has occurred with a stable primary
injector; and o. resetting the relight timer and continuing
operation with the new primary injector.
6. A method of relighting a multi injector combustor in a
turbogenerator, the method comprising: a. determining that the
combustor is operating on a single injector considered the primary
injector; b. determining that the turbine exhaust temperature error
is greater than an allowable error; c. determining that the turbine
exhaust temperature delta is less than an allowable delta; d.
determining that the relight timer has expired; e. turning on the
spark exciter; f. turning on the fuel injector delivering fuel to
the spark exciter area of the combustor; g. turning on fuel
delivery to the then primary fuel injector if the then primary
injector is not the injector delivering fuel to the spark exciter
area of the combustor; h. determining that the turbine exhaust
temperature error is less than an allowable error; i. switching the
primary injector to the next sequential injector, delivering fuel
to the new primary injector and ceasing to deliver fuel to the
initial primary injector; j. resetting the completion timer; k.
determining that the completion timer has expired; l. turning off
the spark exciter; m. turning off the fuel injector delivering fuel
to the spark exciter area of the combustor if that injector is not
the new primary injector leaving the new primary injector as the
only fuel injector delivering fuel to the combustor; n. resetting
the relight timer; o. determining that the turbine exhaust
temperature error is less than an allowable error; and p. resetting
the relight timer and continuing operation with the new primary
injector.
7. A method of relighting a multi injector combustor in a
turbogenerator, the method comprising: a. determining that the
combustor is operating on a single injector considered the primary
injector; b. determining that the turbine exhaust temperature error
is greater than an allowable error; c. determining that the turbine
exhaust temperature delta is less than an allowable delta; d.
determining that the relight timer has expired; e. turning on the
spark exciter; f. turning on the fuel injector delivering fuel to
the spark exciter area of the combustor; g. turning on fuel
delivery to the then primary fuel injector if the then primary
injector is not the injector delivering fuel to the spark exciter
area of the combustor; h. determining that the turbine exhaust
temperature error is less than an allowable error; i. switching the
primary injector to the next sequential injector, delivering fuel
to the new primary injector and ceasing to deliver fuel to the
initial primary injector; j. resetting the completion timer; k.
determining that the completion timer has expired; l. turning off
the spark exciter; m. turning off the fuel injector delivering fuel
to the spark exciter area of the combustor if that injector is not
the new primary injector leaving the new primary injector as the
only fuel injector delivering fuel to the combustor; n. resetting
the relight timer; o. determining that the turbine exhaust
temperature error is less than an allowable error and that the
turbine exhaust temperature delta is greater than an allowable
delta; and p. resetting the relight timer and continuing operation
with the new primary injector.
8. A method of relighting a multi injector combustor in a
turbogenerator, the method comprising: a. determining that the
combustor is operating on a single injector considered the primary
injector; b. determining that the turbine exhaust temperature error
is greater than an allowable error; c. determining that the turbine
exhaust temperature delta is less than an allowable delta; d.
determining that the relight timer has expired; e. turning on the
spark exciter; f. turning on the fuel injector delivering fuel to
the spark exciter area of the combustor; g. turning on fuel
delivery to the then primary fuel injector if the then primary
injector is not the injector delivering fuel to the spark exciter
area of the combustor; h. determining that the turbine exhaust
temperature error is less than an allowable error; i. switching the
primary injector to the next sequential injector, delivering fuel
to the new primary injector and ceasing to deliver fuel to the
initial primary injector; j. resetting the completion timer; k.
determining that the completion timer has expired; l. turning off
the spark exciter; m. turning off the fuel injector delivering fuel
to the spark exciter area of the combustor if that injector is not
the new primary injector leaving the new primary injector as the
only fuel injector delivering fuel to the combustor; n. resetting
the relight timer; o. determining that the turbine exhaust
temperature error is more than an allowable error; p. resetting the
relight timer; q. repeating steps (a) through (n) until it is
determined that relight has occurred with a stable primary
injector; and r. resetting the relight timer and continuing
operation with the new primary injector.
9. A method of relighting a turbogenerator having an annular
combustor with three equally spaced tangential fuel injectors, the
method comprising: a. determining that the combustor is operating
on a single fuel injector considered the primary injector; b.
determining that combustion has ceased; c. turning on the ignitor;
d. determining that the combustor has been relit; e. switching the
primary injector from the primary fuel injector to the next
sequential fuel injector; f. turning off the spark ignitor; g.
determining that relight has occurred; and h. continuing operation
with the new primary injector.
10. A method of relighting a turbogenerator having an annular
combustor with three equally spaced tangential fuel injectors, the
method comprising: a. determining that the combustor is operating
on a single fuel injector considered the primary injector and that
the primary injector is the first fuel injector which delivers fuel
to the spark exciter area of the combustor; b. determining that the
turbine exhaust temperature error is greater than an allowable
error; c. determining that the turbine exhaust temperature delta is
less than an allowable delta; d. determining that the relight timer
has expired; e. turning on the spark exciter; f. turning on the
first fuel injector delivering fuel to the spark exciter area of
the combustor; g. determining that the turbine exhaust temperature
error is less than an allowable error; h. switching the primary
injector from the first fuel injector to the second fuel injector
and delivering fuel to the second fuel injector; i. resetting the
completion timer; j. determining that the completion timer has
expired; k. turning off the spark exciter; l. turning off the first
fuel injector delivering fuel to the spark exciter area of the
combustor; m. resetting the relight timer; n. determining that the
turbine exhaust temperature error is less than an allowable error;
and o. resetting the relight timer and continuing operation with
the second injector.
11. A method of relighting a turbogenerator having an annular
combustor with three equally spaced tangential fuel injectors, the
method comprising: a. determining that the combustor is operating
on a single fuel injector considered the primary injector and that
the primary injector is the first fuel injector which delivers fuel
to the spark exciter area of the combustor; b. determining that the
turbine exhaust temperature error is greater than an allowable
error; c. determining that the turbine exhaust temperature delta is
less than an allowable delta; d. determining that the relight timer
has expired; e. turning on the spark exciter; f. turning on the
first fuel injector delivering fuel to the spark exciter area of
the combustor; g. determining that the turbine exhaust temperature
error is less than an allowable error; h. switching the primary
injector from the first fuel injector to the second fuel injector
as the primary fuel injector and delivering fuel to the second fuel
injector; i. resetting the completion timer; j. determining that
the completion timer has expired; k. turning off the spark exciter;
l. turning off the first fuel injector delivering fuel to the spark
exciter area of the combustor; m. resetting the relight timer; n.
determining that the turbine exhaust temperature error is more than
an allowable error; o. determining that the relight timer has
expired; p. turning on the spark exciter; q. turning on the first
fuel injector delivering fuel to the spark exciter area of the
combustor; r. turning on the second fuel injector and delivering
fuel to the second fuel injector; s. determining that the turbine
exhaust temperature error is less than an allowable error; t.
switching the primary injector from the second fuel injector to the
third fuel injector, delivering fuel to the third fuel injector and
ceasing to deliver fuel to the second fuel injector; u. resetting
the completion timer; v. determining that the completion timer has
expired; w. turning off the spark exciter; x. turning off the first
fuel injector delivering fuel to the spark exciter area of the
combustor; y. resetting the relight timer; z. determining that the
turbine exhaust temperature error is less than an allowable error;
and aa. resetting the relight timer and continuing operation with
the third injector.
12. A method of relighting a turbogenerator having an annular
combustor with three equally spaced tangential fuel injectors, the
method comprising: a. determining that the combustor is operating
on a single fuel injector considered the primary injector and that
the primary injector is the second fuel injector which does not
deliver fuel to the spark exciter area of the combustor; b.
determining that the turbine exhaust temperature error is greater
than an allowable error; c. determining that the turbine exhaust
temperature delta is less than an allowable delta; d. determining
that the relight timer has expired; e. turning on the spark
exciter; f. turning on the first fuel injector delivering fuel to
the spark exciter area of the combustor; g. turning on the second
fuel injector and delivering fuel to the second fuel injector; h.
determining that the turbine exhaust temperature error is less than
an allowable error; i. switching the primary injector from the
second fuel injector to the third fuel injector, delivering fuel to
the third fuel injector and ceasing to deliver fuel to the second
fuel injector; j. resetting the completion timer; k. determining
that the completion timer has expired; l. turning off the spark
exciter; m. turning off the first fuel injector delivering fuel to
the spark exciter area of the combustor; n. resetting the relight
timer; o. determining that the turbine exhaust temperature error is
less than an allowable error; and p. resetting the relight timer
and continuing operation with the third injector.
13. A method of relighting a turbogenerator having an annular
combustor with three equally spaced tangential fuel injectors, the
method comprising: a. determining that the combustor is operating
on a single fuel injector considered the primary injector and that
the primary injector is the second fuel injector which does not
deliver fuel to the spark exciter area of the combustor; b.
determining that the turbine exhaust temperature error is greater
than an allowable error; c. determining that the turbine exhaust
temperature delta is less than an allowable delta; d. determining
that the relight timer has expired; e. turning on the spark
exciter; f. turning on the first fuel injector delivering fuel to
the spark exciter area of the combustor; g. turning on the second
fuel injector and delivering fuel to the second fuel injector; h.
determining that the turbine exhaust temperature error is less than
an allowable error; i. switching the primary fuel injector from the
second fuel injector to the third fuel injector, delivering fuel to
the third fuel injector and ceasing to deliver fuel to the second
fuel injector; j. resetting the completion timer; k. determining
that the completion timer has expired; l. turning off the spark
exciter; m. turning off the first fuel injector delivering fuel to
the spark exciter area of the combustor; n. resetting the relight
timer; o. determining that the turbine exhaust temperature error is
more than an allowable error; p. determining that the relight timer
has expired; q. turning on the spark exciter; r. turning on the
first fuel injector delivering fuel to the spark exciter area of
the combustor; s. turning on the third fuel injector and delivering
fuel to the third fuel injector; t. determining that the turbine
exhaust temperature error is less than an allowable error; u.
switching the primary injector from the third fuel injector to the
first fuel injector as the primary fuel injector and ceasing to
deliver fuel to the third fuel injector; v. resetting the
completion timer; w. determining that the completion timer has
expired; x. turning off the spark exciter; y. resetting the relight
timer; z. determining that the turbine exhaust temperature error is
less than an allowable error; and aa. resetting the relight timer
and continuing operation with the first injector.
14. A method of relighting a turbogenerator having an annular
combustor with three equally spaced tangential fuel injectors, the
method comprising: a. determining that the combustor is operating
on a single fuel injector considered the primary injector and that
the primary injector is the third fuel injector which does not
deliver fuel to the spark exciter area of the combustor; b.
determining that the turbine exhaust temperature error is greater
than an allowable error; c. determining that the turbine exhaust
temperature delta is less than an allowable delta; d. determining
that the relight timer has expired; e. turning on the spark
exciter; f. turning on the first fuel injector delivering fuel to
the spark exciter area of the combustor; g. turning on the third
fuel injector and delivering fuel to the third fuel injector; h.
determining that the turbine exhaust temperature error is less than
an allowable error; i. switching the primary fuel injector from the
third fuel injector to the first fiel injector and ceasing to
deliver fuel to the third fuel injector; j. resetting the
completion timer; k. determining that the completion timer has
expired; l. turning off the spark exciter; m. resetting the relight
timer; n. determining that the turbine exhaust temperature error is
less than an allowable error; and o. resetting the relight timer
and continuing operation with the first injector.
15. A method of relighting a turbogenerator having an annular
combustor with three equally spaced tangential fuel injectors, the
method comprising: a. determining that the combustor is operating
on a single fuel injector considered the primary injector and that
the primary injector is the third fuel injector which does not
deliver fuel to the spark exciter area of the combustor; b.
determining that the turbine exhaust temperature error is greater
than an allowable error; c. determining that the turbine exhaust
temperature delta is less than an allowable delta; d. determining
that the relight timer has expired; e. turning on the spark
exciter; f. turning on the first fuel injector delivering fuel to
the spark exciter area of the combustor; g. turning on the third
fuel injector and delivering fuel to the third fuel injector; h.
determining that the turbine exhaust temperature error is less than
an allowable error; i. switching the primary fuel injector from the
third fuel injector to the first fuel injector and ceasing to
deliver fuel to the third fuel injector; j. resetting the
completion timer; k. determining that the completion timer has
expired; l. turning off the spark exciter; m. resetting the relight
timer; n. determining that the turbine exhaust temperature error is
more than an allowable error; o. determining that the relight timer
has expired; p. turning on the spark exciter; q. turning on the
first fuel injector delivering fuel to the spark exciter area of
the combustor; r. determining that the turbine exhaust temperature
error is less than an allowable error; s. switching the primary
fuel injector from the first fuel injector to the second fuel
injector and delivering fuel to the second fuel injector; t.
resetting the completion timer; u. determining that the completion
timer has expired; v. turning off the spark exciter; w. turning off
the first fuel injector; x. resetting the relight timer; y.
determining that the turbine exhaust temperature error is less than
an allowable error; and z. resetting the relight timer and
continuing operation with the second injector.
16. A method of maintaining combustion in a turbogenerator, the
method comprising: providing a brake resistor across the DC bus of
the power controller for the turbogenerator; and during idle or no
load operating conditions, dissipating energy in the brake resistor
to provide a minimum load for the turbogenerator.
17. The method of claim 16, wherein said turbogenerator includes a
combustor having a plurality of fuel injectors and said method
includes the additional steps of: a. determining that the combustor
is operating on a single injector considered the primary injector;
b. determining that combustion has ceased; c. turning on the
ignitor; d. determining that the combustor has been relit; e.
switching the primary injector to the next sequential injector: f.
turning off the spark exciter; and g. continuing operation with the
new primary injector.
18. The method of claim 16, wherein said turbogenerator includes a
combustor having a plurality of fuel injectors and said method
includes the additional steps of: a. determining that the combustor
is operating on a single injector considered the primary injector;
b. determining that combustion has ceased; c. determining that the
relight timer has expired; d. turning on the spark exciter; e.
turning on the fuel injector delivering fuel to the spark exciter
area of the combustor; f. turning on fuel delivery to the then
primary fuel injector if the then primary injector is not the
injector delivering fuel to the spark exciter area of the
combustor; g. determining that the combustor has been relit; h.
switching the primary injector to the next sequential injector: i.
turning off the spark exciter; j. turning off the fuel injector
delivering fuel to the spark exciter area of the combustor if that
injector is not the new primary injector; k. resetting the relight
timer; l. determining that relight has occurred; and m. resetting
the relight timer and continuing operation with the new primary
injector.
19. A method of maintaining combustion in a turbogenerator, the
method comprising: providing a brake resistor across the DC bus of
the power controller for the turbogenerator; and during an off load
event, dissipating energy in the brake resistor to lessen the rate
of reducing fuel flow to the combustor.
20. The method of claim 19, wherein said turbogenerator includes a
combustor having a plurality of fuel injectors and said method
includes the additional steps of a. determining that the combustor
is operating on a single injector considered the primary injector;
b. determining that combustion has ceased; c. turning on the
ignitor; d. determining that the combustor has been relit; e.
switching the primary injector to the next sequential injector: f.
turning off the spark exciter; and g. continuing operation with the
new primary injector.
21. The method of claim 19, wherein said turbogenerator includes a
combustor having a plurality of fuel injectors and said method
includes the additional steps of: a. determining that the combustor
is operating on a single injector considered the primary injector;
b. determining that combustion has ceased; c. determining that the
relight timer has expired; d. turning on the spark exciter; e.
turning on the fuel injector delivering fuel to the spark exciter
area of the combustor; f. turning on fuel delivery to the then
primary fuel injector if the then primary injector is not the
injector delivering fuel to the spark exciter area of the
combustor; g. determining that the combustor has been relit; h.
switching the primary injector to the next sequential injector: i.
turning off the spark exciter; j. turning off the fuel injector
delivering fuel to the spark exciter area of the combustor if that
injector is not the new primary injector; k. resetting the relight
timer; l. determining that relight has occurred; and m. resetting
the relight timer and continuing operation with the new primary
injector.
22. A method of maintaining combustion in a turbogenerator, the
method comprising: providing a brake resistor across the DC bus of
the power controller for the turbogenerator; during idle or no load
operating conditions, dissipating energy in the brake resistor to
provide a minimum load for the turbogenerator; and during an off
load event, dissipating energy in the brake resistor to lessen the
rate of reducing fuel flow to the combustor.
23. The method of claim 22, wherein said turbogenerator includes a
combustor having a plurality of fuel injectors and said method
includes the additional steps of: a. determining that the combustor
is operating on a single injector considered the primary injector;
b. determining that combustion has ceased; c. turning on the
ignitor; d. determining that the combustor has been relit; e.
switching the primary injector to the next sequential injector: f.
turning off the spark exciter; and g. continuing operation with the
new primary injector.
24. The method of claim 22, wherein said turbogenerator includes a
combustor having a plurality of fuel injectors and said method
includes the additional steps of: a. determining that the combustor
is operating on a single injector considered the primary injector;
b. determining that combustion has ceased; c. determining that the
relight timer has expired; d. turning on the spark exciter; e.
turning on the fuel injector delivering fuel to the spark exciter
area of the combustor; f. turning on fuel delivery to the then
primary fuel injector if the then primary injector is not the
injector delivering fuel to the spark exciter area of the
combustor; g. determining that the combustor has been relit; h.
switching the primary injector to the next sequential injector: i.
turning off the spark exciter; j. turning off the fuel injector
delivering fuel to the spark exciter area of the combustor if that
injector is not the new primary injector; k. resetting the relight
timer; l. determining that relight has occurred; and m. resetting
the relight timer and continuing operation with the new primary
injector.
25. A system for relighting a multi injector combustor in a
turbogenerator, the system comprising: a. means for determining
that the combustor is operating on a single injector considered the
primary injector; b. means for determining that combustion has
ceased; c. means for turning on the ignitor; d. means for
determining that the combustor has been relit; e. means for
switching the primary injector to the next sequential injector: f.
means for turning off the spark exciter; and g. means for
continuing operation with the new primary injector.
26. A system for relighting a multi injector combustor in a
turbogenerator, the system comprising: a. means for determining
that the combustor is operating on a single injector considered the
primary injector; b. means for determining that combustion has
ceased; c. means for turning on the ignitor; d. means for
determining that the combustor has been relit; e. means for
switching the primary injector to the next sequential injector: f.
means for turning off the spark exciter; g. means for determining
that relight has occurred; and h. means for continuing operation
with the new primary injector.
27. A system for relighting a multi injector combustor in a
turbogenerator, the system comprising: a. means for determining
that the combustor is operating on a single injector considered the
primary injector; b. means for determining that combustion has
ceased; c. means for turning on the ignitor; d. means for
determining that the combustor has been relit; e. means for
switching the primary injector to the next sequential injector: f.
means for turning off the spark exciter; g. means for determining
that relight has not occurred; h. means for repeating steps (a)
through (f) until it is determined that relight has occurred with a
stable primary injector; and i. means for continuing operation with
the new primary injector.
28. A system for relighting a multi injector combustor in a
turbogenerator, the system comprising: a. means for determining
that the combustor is operating on a single injector considered the
primary injector; b. means for determining that combustion has
ceased; c. means for determining that the relight timer has
expired; d. means for turning on the spark exciter; e. means for
turning on the fuel injector delivering fuel to the spark exciter
area of the combustor; f. means for turning on fuel delivery to the
then primary fuel injector if the then primary injector is not the
injector delivering fuel to the spark exciter area of the
combustor; g. means for determining that the combustor has been
relit; h. means for switching the primary injector to the next
sequential injector: i. means for turning off the spark exciter; j.
means for turning off the fuel injector delivering fuel to the
spark exciter area of the combustor if that injector is not the new
primary injector; k. means for resetting the relight timer; l.
means for determining that relight has occurred; and m. means for
resetting the relight timer and continuing operation with the new
primary injector.
29. A system for relighting a multi injector combustor in a
turbogenerator, the system comprising: a. means for determining
that the combustor is operating on a single injector considered the
primary injector; b. means for determining that combustion has
ceased; c. means for determining that the relight timer has
expired; d. means for turning on the spark exciter; e. means for
turning on the fuel injector delivering fuel to the spark exciter
area of the combustor; f. means for turning on fuel delivery to the
then primary fuel injector if the then primary injector is not the
injector delivering fuel to the spark exciter area of the
combustor; g. means for determining that the combustor has been
relit; h. means for switching the primary injector to the next
sequential injector: i. means for turning off the spark exciter; j.
means for turning off the fuel injector delivering fuel to the
spark exciter area of the combustor if that injector is not the new
primary injector; k. means for resetting the relight timer; l.
means for determining that relight has not occurred; m. means for
resetting the relight timer; n. means for repeating steps (a)
through (k) until it is determined that relight has occurred with a
stable primary injector; and o. means for resetting the relight
timer and continuing operation with the new primary injector.
30. A system for relighting a turbogenerator having an annular
combustor with three equally spaced tangential fuel injectors, the
system comprising: a. means for determining that the combustor is
operating on a single fuel injector considered the primary
injector; b. means for determining that combustion has ceased; c.
means for turning on the ignitor; d. means for determining that the
combustor has been relit; e. means for switching the primary
injector from the primary fuel injector to the next sequential fuel
injector; f. means for turning off the spark ignitor; g. means for
determining that relight has occurred; and h. means for continuing
operation with the new primary injector.
31. A system for maintaining combustion in a turbogenerator, the
system comprising: a brake resistor disposed across the DC bus of
the power controller for the turbogenerator; and means for
dissipating energy in said brake resistor during idle or no load
operating conditions to provide a minimum load for the
turbogenerator.
32. The system of claim 31, wherein said turbogenerator includes a
combustor having a plurality of fuel injectors and said system
additionally includes: a. means for determining that the combustor
is operating on a single injector considered the primary injector;
b. means for determining that combustion has ceased; c. means for
turning on the ignitor; d. means for determining that the combustor
has been relit; e. means for switching the primary injector to the
next sequential injector: f. means for turning off the spark
exciter; and g. means for continuing operation with the new primary
injector.
33. A system of maintaining combustion in a turbogenerator, the
system comprising: a brake resistor disposed across the DC bus of
the power controller for the turbogenerator; and means for
dissipating energy in said brake resistor during an off load event
to lessen the rate of reducing fuel flow to the combustor.
34. The system of claim 33, wherein said turbogenerator includes a
combustor having a plurality of fuel injectors and said system
additionally includes: a. means for determining that the combustor
is operating on a single injector considered the primary injector;
b. means for determining that combustion has ceased; c. means for
turning on the ignitor; d. means for determining that the combustor
has been relit; e. means for switching the primary injector to the
next sequential injector: f. means for turning off the spark
exciter; and g. means for continuing operation with the new primary
injector.
35. A system of maintaining combustion in a turbogenerator, the
system comprising: a brake resistor disposed across the DC bus of
the power controller for the turbogenerator; means for dissipating
energy in said brake resistor during idle or no load operating
conditions to provide a minimum load for the turbogenerator; and
means for dissipating energy in said brake resistor during an off
load event to lessen the rate of reducing fuel flow to the
combustor.
Description
TECHNICAL FIELD
[0001] This invention relates to the general field of combustion
controls, and more particularly to an improved method and system
for controlling and automatically relighting a turbogenerator
combustor under certain conditions.
BACKGROUND OF THE INVENTION
[0002] A turbogenerator with a shaft mounted permanent magnet
motor/generator can be utilized to provide electrical power for a
wide range of utility, commercial and industrial applications.
While an individual permanent magnet turbogenerator may only
generate 20 to 100 kilowatts, powerplants of up to 500 kilowatts or
greater are possible by linking numerous permanent magnet
turbogenerators together. Peak load shaving power, grid parallel
power, standby power, and remote location (stand-alone) power are
just some of the potential applications for which these
lightweight, low noise, low cost, environmentally friendly, and
thermally efficient units can be useful.
[0003] The conventional power control system for a turbogenerator
produces constant frequency, three phase electrical power that
closely approximates the electrical power produced by utility
grids. Key aspects of such a power generation system are
availability and reliability.
[0004] In grid-connect power generation, lack of availability can
result in penalties from the local utility. Since many utility
users are charged variable rates depending upon the amount of power
drawn during a given period of time, the lowest $/kWh is charged
when power is drawn at lower levels than some negotiated base.
Power drawn above the base level will usually have greatly
increased fees and sometimes a penalty associated with it. While
grid-connect power generation can be used to provide less expensive
power when more than the utility base level of power is required,
should this grid-connect power generation fail, or otherwise be
unavailable, greater costs to the user would ensue.
[0005] Availability and reliability are even more important in a
standalone system in which the turbogenerator itself is providing
the entire load for a user. If the turbogenerator is unavailable,
lengthy interruptions to all aspects of a user's business can occur
and result in significant financial loss to the user. For remote
installations, the turbogenerator could be down for a long period
of time since it might take a while for a service person to provide
support at the remote site.
[0006] In a gas turbine engine, inlet air is continuously
compressed, mixed with fuel in an inflammable proportion, and then
contacted with an ignition source to ignite the mixture which will
then continue to burn. The heat energy thus released then flows in
the combustion gases to a turbine where it is converted to rotary
energy for driving equipment such as an electrical generator. The
combustion gases are then exhausted to atmosphere after giving up
some of their remaining heat to the incoming air provided from the
compressor.
[0007] Quantities of air greatly in excess of stoichiometric
amounts are normally compressed and utilized to keep the combustor
liner cool and dilute the combustor exhaust gases so as to avoid
damage to the turbine nozzle and blades. Generally, primary
sections of the combustor are operated near stoichiometric
conditions which produce combustor gas temperatures up to
approximately four thousand (4,000) degrees Fahrenheit. Further
along the combustor, secondary air is admitted which raises the
air-fuel ratio and lowers the gas temperatures so that the gases
exiting the combustor are in the range of two thousand (2,000)
degrees Fahrenheit.
[0008] It is well established that NOx formation is
thermodynamically favored at high temperatures. Since the NOx
formation reaction is so highly temperature dependent, decreasing
the peak combustion temperature can provide an effective means of
reducing NOx emissions from gas turbine engines as can limiting the
residence time of the combustion products in the combustion zone.
Operating the combustion process in a very lean condition (i.e.,
high excess air) is one of the simplest ways of achieving lower
temperatures and hence lower NOx emissions. Very lean ignition and
combustion, however, inevitably result in incomplete combustion and
the attendant emissions which result therefrom. In addition,
combustion processes are difficult to sustain at these extremely
lean operating conditions.
SUMMARY OF THE INVENTION
[0009] The invention is directed to a multi-injector combustion
system in which a brake resistor is utilized to provide a minimum
load for the combustor system during idle or low power operation of
the permanent magnet turbogenerator/motor and also to absorb power
during transients to prevent flame out of the combustor. In
addition, during single injector operation, a relighting method and
system are provided to relight the combustor and prevent the
necessity of a complete shutdown of the system. The method and
system includes switching between the multiple injectors to find
the most stable injector in single injector operation.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Having thus described the present invention in general
terms, reference will now be made to the accompanying drawings in
which:
[0011] FIG. 1 is a perspective view, partially cut away, of a
turbogenerator having the combustion control method and system of
the present invention;
[0012] FIG. 2 is a plan view of a combustor housing for the
turbogenerator of FIG. 1;
[0013] FIG. 3 is a sectional view of the combustor housing of FIG.
2 taken along line 3-3 of FIG. 2;
[0014] FIG. 4 is a sectional view of the combustor housing of FIG.
3 taken along line 4-4 of FIG. 3;
[0015] FIG. 5 is a detailed block diagram of a power controller for
use with the turbogenerator of FIG. 1;
[0016] FIG. 6 is a detailed block diagram of the power controller
of FIG. 5 having a dynamic brake resistor; and
[0017] FIG. 7 is an auto relight flow diagram for automatically
relighting the turbogenerator combustor after a flame out.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] The turbogenerator 12 having the combustion method and
system of the present invention is illustrated in FIG. 1. The
turbogenerator 12 generally comprises a permanent magnet generator
20, a power head 21, a combustor 22 and a recuperator (or heat
exchanger) 23.
[0019] The permanent magnet generator 20 includes a permanent
magnet rotor or sleeve 26, having a permanent magnet disposed
therein, rotatably supported within a permanent magnet generator
stator 27 by a pair of spaced journal bearings. Radial permanent
magnet stator cooling fins 28 are enclosed in an outer cylindrical
sleeve 29 to form an annular air flow passage which cools the
stator 27 and thereby preheats the air passing through on its way
to the power head 21.
[0020] The power head 21 of the turbogenerator 12 includes
compressor 30, turbine 31, and bearing rotor 32 through which the
tie rod 33 to the permanent magnet rotor 26 passes. The compressor
30, having compressor impeller or wheel 34 which receives preheated
air from the annular air flow passage in cylindrical sleeve 29
around the stator 27, is driven by the turbine 31 having turbine
wheel 35 which receives heated exhaust gases from the combustor 22
supplied with preheated air from recuperator 23. The compressor
wheel 34 and turbine wheel 35 are supported on a bearing shaft or
rotor 32 having a radially extending bearing rotor thrust disk 36.
The bearing rotor 32 is rotatably supported by a single journal
bearing within the center bearing housing 37 while the bearing
rotor thrust disk 36 at the compressor end of the bearing rotor 32
is rotatably supported by a bilateral thrust bearing.
[0021] Intake air is drawn through the permanent magnet generator
20 by the compressor 30 which increases the pressure of the air and
forces it into the recuperator 23. The recuperator 23 includes an
annular housing 40 having a heat transfer section 41, an exhaust
gas dome 42 and a combustor dome 43. Exhaust heat from the turbine
31 is used to preheat the air before it enters the combustor 22
where the preheated air is mixed with fuel and burned. The
combustion gases are then expanded in the turbine 31 which drives
the compressor 30 and the permanent magnet rotor 26 of the
permanent magnet generator 20 which is mounted on the same shaft as
the turbine 31. The expanded turbine exhaust gases are then passed
through the recuperator 23 before being discharged from the
turbogenerator 12.
[0022] The combustor housing 39 of the combustor 22 is illustrated
in FIGS. 2-4, and generally comprises a cylindrical outer liner 44
and a tapered inner liner 46 which, together with the combustor
dome 43, form a generally expanding annular combustion housing or
chamber 39 from the combustor dome 43 to the turbine 31. A
plurality of fuel injector guides 49a, 49b, and 49c may position
the fuel injectors 14a, 14b, and 14c, respectively, to tangentially
introduce a fuel/air mixture at the combustor dome 43 end of the
annular combustion housing 39 along the fuel injector axis or
centerline 47. This same centerline 47 includes an ignitor cap to
position an ignitor (not shown) within the combustor housing 39.
The combustion dome 43 is rounded out to permit the swirl pattern
from the fuel injectors 14a, 14b, and 14c to fully develop and also
to reduce structural stress loads in the combustor.
[0023] A flow control baffle 48 extends from the tapered inner
liner 46 into the annular combustion housing 39. The baffle 48,
which would be generally skirt-shaped, would extend between
one-third and one-half of the distance between the tapered inner
liner 46 and the cylindrical outer liner 44. Three rows each of a
plurality of spaced offset air dilution holes 52, 53, and 54 in the
tapered inner liner 46 underneath the flow control baffle 48
introduce dilution air into the annular combustion housing 39. The
first two (2) rows of air dilution holes 52 and 53 (closest to the
fuel injector centerline 47) may be the same size with both,
however, smaller than the third row of air dilution holes 54.
[0024] In addition, two (2) rows each of a plurality of spaced air
dilution holes 50 and 51 in the cylindrical outer liner 44,
introduce more dilution air downstream from the flow control baffle
48. The plurality of holes 50 closest to the flow control baffle 48
may be larger and less numerous than the second row of holes
51.
[0025] Fuel can be provided individually to each fuel injector 14a,
14b, and 14c, or, as shown in FIG. 1, a fuel manifold 15 can be
used to supply fuel to all three (3) fuel injectors. The fuel
manifold 15 includes a fuel inlet 16 to receive fuel from a fuel
source (not shown). Flow control valves 17 are provided in each of
the fuel lines from the manifold 15 to the individual fuel
injectors 14a, 14b, and 14c. In order to sustain low power
operation, maintain fuel economy and low emissions, the flow
control valves 17 can be individually controlled to an on/off
position (to separately use any combination of fuel injectors
individually) or they can be modulated together. The flow control
valves 17 can be opened by fuel pressure or their operation can be
controlled or augmented with a solenoid.
[0026] A more detailed description of the combustor and fuel
injectors can be found in U.S. Pat. No. 5,850,732, issued Dec. 22,
1998 to Jeffrey W. Willis et al, entitled "Low Emissions Combustion
System", assigned to the same assignee as this application and
hereby incorporated by reference.
[0027] The system has a steady-state turbine exhaust temperature
limit, and the turbogenerator operates at this limit at most speed
conditions to maximize system efficiency. This turbine exhaust
temperature limit is decreased at low ambient temperatures to
prevent engine surge.
[0028] Referring to FIG. 5, there is illustrated a power controller
140 for use with the turbogenerator of FIG. 1. This power
controller 140, which may be digital, provides a distributed
generation power networking system in which bi-directional (i.e.
reconfigurable) power converters are used with a common DC bus 154
for permitting compatibility between one or more energy components.
Each power converter 144 and 146 operates essentially as a
customized bi-directional switching converter configured, under the
control of power controller 140, to provide an interface for a
specific energy component to DC bus 154. Power controller 140
controls the way in which each energy component, at any moment,
will sink or source power, and the manner in which DC bus 154 is
regulated. In this way, various energy components can be used to
supply, store and/or use power in an efficient manner.
[0029] The energy components include an energy source 142 such as
the turbogenerator 12, utility/load 148, and storage device 150
such as a battery. The energy source 142 is connected to DC bus 154
via power converter 144 under the control of signal processor 145.
Energy source 142 may produce AC that is applied to power converter
146 under control of signal processor 147. DC bus 154 connects
power converter 144 to utility/load 148 and additional energy
components. Main CPU 149 provides supervisory operation of power
controller 140, specifically signal processors 145 and 147.
[0030] Each power converter 144, 146, and 152 operates essentially
as a customized, bi-directional switching converter under the
control of main CPU 149, which uses signal processors 145 and 147
to perform its operations. Main CPU 149 provides both local control
and sufficient intelligence to form a distributed processing
system. Each power converter 144, 146, and 152 is tailored to
provide an interface for a specific energy component to DC bus 154.
Main CPU 149 controls the way in which each energy component 142,
148, and 150 sinks or sources power and DC bus 154 is regulated at
any time. In particular, main CPU 149 reconfigures the power
converters 144, 146, and 152 into different configurations for
different modes of operation. In this way, various energy
components 142, 148, and 150 can be used to supply, store and/or
use power in an efficient manner.
[0031] In the case of a turbogenerator 12 as the energy source 142,
a conventional system regulates turbine speed to control the output
or bus voltage. In the power controller 140, the bi-directional
controller functions independently of turbine speed to regulate the
bus voltage.
[0032] FIG. 5 generally illustrates the system topography with the
DC bus 154 at the center of a star pattern network. In general,
energy source 12 provides power to DC bus via power converter 144
during normal power generation mode. Similarly, during power
generation, power converter 146 converts the power on DC bus 154 to
the form required by utility/load 148. During utility start up,
power converters 144 and 146 are controlled by the main processor
to operate in different manners. For example, if energy is needed
to start the turbogenerator 12, this energy may come from
load/utility 148 (utility start) or from energy source 150 (battery
start). During a utility start up, power converter 146 is required
to apply power from load 148 to DC bus for conversion by power
converter 144 into the power required by the turbogenerator 12 to
start up. During utility start, the turbogenerator 12 is controlled
in a local feedback loop to maintain the turbine revolutions per
minute (RPM). Energy storage or battery 150 is disconnected from DC
bus while load/utility grid regulates V.sub.DC on DC bus 154.
[0033] Similarly, in a battery start, the power applied to DC bus
154 from which turbogenerator 12 may be started, may be provided by
energy storage 150. Energy storage 150 has its own power conversion
circuit in power converter 152, which limits the surge current into
the DC bus 154 capacitors, and allows enough power to flow to DC
bus 154 to start turbogenerator 12.
[0034] A more detailed description of the power controller can be
found in U.S. patent application Ser. No. 207,817, filed Dec. 8,
1998 by Mark G. Gilbreth et al, entitled "Power Controller",
assigned to the same assignee as this application and hereby
incorporated by reference.
[0035] FIG. 6 illustrates a power controller of FIG. 5 having a
dynamic brake resistor and associated controls. The turbogenerator
12 produces three phase AC power which is fed to AC to DC converter
144, referred to here as the engine control module. The DC voltage
is supplied to DC bus 154 which is connected to DC to AC converter
126, referred to here as the load control module, which is
connected to the load 148, such as the utility grid.
[0036] A brake resistor 170 is connected across the DC bus 154.
Power in the DC bus can be dissipated in brake resistor 170 by
modulation of switch 172. A voltage sensor 174 is also connected
across the DC bus 154 to produce a DC bus voltage signal 176 which
is compared in comparator 178 with a brake resistor turn on voltage
signal 180 to produce a DC bus error signal 182. The brake resistor
turn on voltage signal 180 is adjustable by CPU 149.
[0037] The DC bus error signal 182 from comparator 178 is used to
control the modulation of switch 172 after being conditioning
through a proportional integral compensator 184, a brake resistor
temperature feedback limit 186, a pulse width modulator 188 and
gate drive 190. The switch 172 may be an IGBT switch although
conventional or newly developed switches can be utilized as well.
The switch 172 is controlled in accordance with the magnitude of
the voltage on DC bus 154. Signal processor 147 typically maintains
the DC bus voltage to a selected value by appropriate control of
power flows in the load control module 146 and the engine control
module 144. If a rise in voltage on the DC bus is detected, the
brake resistor 170 is modulated on and off until the bus voltage is
restored to its desired level.
[0038] As outlined above, the turbogenerator combustion system is a
low emission system coupled with a recuperator creating an
efficient gas turbine in the turbogenerator. In order to achieve
low emissions, the fuel source is diluted into a large volume of
air. Little fuel is required at idle speeds because the recuperator
is capable of supplying most of the energy required to self-sustain
gas turbine operation. A high air-to-fuel ratio (AFR) mixture is
created with large amounts of air flow and low fuel flow, thus
reducing the stability of the combustion. Flame out conditions
occur (combustion ceases) when the AFR reaches too high a level. Of
course, flame out can result in a time consuming shutdown and
restart cycle.
[0039] In a multi-injector combustion system, the first line of
defense for preventing flame out is to operate on fewer injectors.
When low levels of fuel flow are detected, the delivery of fuel to
some injectors are turned off. By turning off injectors, fuel flow
can be concentrated into fewer injectors to reduce AFR and increase
combustion stability. At very low power levels, even operating on a
single injector may not provide low enough AFR levels to prevent
flame out conditions.
[0040] The brake resistor 170 can be extremely helpful in
maintaining combustion flame stability. For example, during an off
load event, the power flowing into the utility/load 148 is suddenly
reduced, and if the power produced by the gas turbine engine is
reduced at the same rate, the fuel flow can be reduced too rapidly
to maintain combustion and flame out can occur. With the brake
resistor able to absorb excess energy that is produced by the gas
turbine engine but not supplied to the utility/load 148, the fuel
flow to the combustor can be reduced more gradually at a rate that
can be sustained by the combustion system. In other words, the fuel
flow can be reduced at a rate that considers the maintaining of
combustion rather than just rapidly reducing fuel flow to
compensate for the off load event. The brake resistor 170, by
absorbing excess energy, permits a slower deceleration since any
load not transferred out of the power converter 146 can be absorbed
by the brake resistor 170.
[0041] In addition, the brake resistor 170 can provide a minimum
load during idle or no load operating conditions. With the external
load disconnected, the combustion system might not otherwise be
able to maintain combustion without this minimum load supplied by
the brake resistor 170.
[0042] While flame out conditions are certainly not desired, the
high AFR mixture provides a unique opportunity to relight the gas
turbine combustor without shutting the gas turbine down. Typically
gas turbines systems require controls to shutdown the turbine,
bring speed down to zero rpm, and then issue a restart command in
order to regain operation after a flame out condition occurs. With
a high AFR mixture, the gas turbine is often below its ideal AFR
for light off. By turning on the ignition system and allowing the
temperature control to add more fuel, an ideal AFR will be found
that will reignite combustion in the gas turbine. Significant
interruption can be avoided by reigniting the gas turbine engine
without having to perform a complete shutdown.
[0043] Without combustion power it is difficult to keep a gas
turbine rotating without some external power source. The power
controller 140 can provide added help to the relight process by
supplying power from a power source 148 or 150 to keep the gas
turbine rotating when a flameout has occurred. Someone skilled in
the art should understand that any type of starter motor
configuration would provide the same capability.
[0044] A flow diagram for the automatic relight process is
illustrated in FIG. 7. The logic first determines if the combustion
system is operating on a single injector, block 200. Single
injector operation is an indication of low fuel flow being
delivered to the combustor and a potential for flame out exists. If
the combustor is operating on a single injector, block 200, block
202 determines whether the turbine exhaust temperature (TET) error
is greater than an allowable error which is a function of gas
turbine speed. The TET error is the difference between the ideal
operation temperature (set point) and the TET feedback (actual
TET). If the TET error is greater than an allowable error, block
202, block 204 determines if the TET delta is less than an
allowable delta, which is also a function of gas turbine speed. The
TET delta is the rate of change of TET. If the system is not
operating on a single injector, block 200, or the TET error is not
greater than the allowable error, block 202, or the TET delta is
not less than the allowable delta, block 204, the relight timer is
reset in block 206 and operation continues on the same primary
injector.
[0045] The relight process begins when flame out detection
described in blocks 200, 202, and 204 exists for a time period that
allows the relight timer of block 208 to expire. At this time, the
spark exciter or ignitor is turned on and the injector (injector
14a also referred to in FIG. 7 as injector 1) flowing fuel directly
in the ignition system path is enabled together with the primary
injector that the gas turbine is currently using to deliver fuel,
block 210. Evaluating block 212 to determine if the TET error is
less than allowable error indicates whether relight of the gas
turbine has occurred. Once relight is detected, block 212, the
primary injector is switched from the current injector to it
adjacent injector, block 214, and the completion timer is reset.
The completion timer provides a period for combustion and TET to
stabilize after gas turbine relight. If the completion timer has
expired, block 216, the spark exciter and initial injector are
turned off, block 218 with only the new primary injector enabled,
block 220, followed by a resetting of the relight timer, block
206.
[0046] Successive iterations through the relight logic of FIG. 7
will rotate the primary injector until the most stable injector is
found. In this system of three injectors 14a, 14b and 14c, assume
that the injector flowing fuel directly in the ignition system path
is injector 14a. When the system initially lights assume that
injector 14b is assigned as the primary injector as discussed
above. When the relight logic commences the spark exciter and
injector 14a will be enabled with the primary injector (now
injector 14b). Once relight of the gas turbine is detected the
primary injector designation is reassigned to injector 14c. At this
time injector 14b is shutoff and injector 14c is enabled. Fuel
flowing from injector 14c will ignite via the combustion process
occurring at injector 14a. Once the completion timer expires, spark
exciter and injector 14a are disabled leaving only the primary
injector (injector 14c) operating to maintain combustion. Stepping
through the relight logic on the next iteration would transfer
operation from injector 14c to injector 14a. Eventually one
injector is found to be more stable than the other injectors are
and the system continues operating with this injector as the
primary injector.
[0047] The system is declared unrecoverable and a shutdown occurs
when the relight process of blocks 210, 212 is unsuccessful and the
flame out condition exists for a lengthy period of time. The
relight logic has only a window of time during this detection
period to recover prior to declaring an unrecoverable fault.
[0048] A key point in the logic is the switching of injectors. The
combustion system described illustrates three injectors by way of
example. In such a three injector system, if two injectors were
found to be less stable than the third injector, the system would
execute the relight logic until the stable injector was found. At
this time, the conditions of block 202 and 204 will not exist and
the auto relight and injector switching logic will not be
executed.
[0049] While specific embodiments of the invention have been
illustrated and described, it is to be understood that these are
provided by way of example only and that the invention is not to be
construed as being limited thereto but only by the proper scope of
the following claims.
* * * * *