U.S. patent application number 13/127726 was filed with the patent office on 2011-10-27 for valves for gas-turbines and multipressure gas-turbines, and gas-turbines therewith.
This patent application is currently assigned to ETV ENERGY LTD.. Invention is credited to David Lior.
Application Number | 20110262269 13/127726 |
Document ID | / |
Family ID | 41718509 |
Filed Date | 2011-10-27 |
United States Patent
Application |
20110262269 |
Kind Code |
A1 |
Lior; David |
October 27, 2011 |
VALVES FOR GAS-TURBINES AND MULTIPRESSURE GAS-TURBINES, AND
GAS-TURBINES THEREWITH
Abstract
A multiport valve suitable for use with a gas-turbine allowing
switching of a mode of gas-turbine operation between a Brayton
cycle and an inverse Brayton cycle, and a gas-turbine configured to
switch between a high-pressure operation mode according to a
Brayton cycle and a low-pressure operation mode according to an
inverse Brayton cycle employing the valve are provided. Also
provided are a method and apparatus for operating a gas-turbine
according to an inverse Brayton cycle.
Inventors: |
Lior; David; (Herzliya,
IL) |
Assignee: |
ETV ENERGY LTD.
Herzliya
IL
|
Family ID: |
41718509 |
Appl. No.: |
13/127726 |
Filed: |
November 18, 2009 |
PCT Filed: |
November 18, 2009 |
PCT NO: |
PCT/IB2009/055154 |
371 Date: |
June 22, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61116394 |
Nov 20, 2008 |
|
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|
Current U.S.
Class: |
415/180 |
Current CPC
Class: |
F02C 6/006 20130101;
F01D 17/10 20130101; F02C 7/08 20130101; F02C 9/18 20130101; F02C
1/08 20130101 |
Class at
Publication: |
415/180 |
International
Class: |
F01D 5/08 20060101
F01D005/08 |
Claims
1. A gas-turbine configured for operation according to both
Brayton-cycle and inverse-Brayton cycle, comprising: a) a multiport
valve including movable valve members and at least five ports
comprising: a compressor-outlet inlet port, an ambient inlet port,
a heat-exchanger cold-stream inlet outlet port, an exhaust outlet
port, and a fifth port; b) a compressor outlet of a compressor in
fluid communication with said compressor-outlet inlet port; and c)
a heat-exchanger cold-stream inlet of a heat-exchanger in fluid
communication with said heat-exchanger cold-stream inlet outlet
port; wherein during Brayton-cycle operation of the gas-turbine: a
valve member blocks fluid communication between said
compressor-outlet inlet port and said exhaust outlet port, and a
valve member blocks fluid communication between said ambient inlet
port and said heat-exchanger cold-stream inlet outlet port; and
during inverse Brayton-cycle operation of the gas-turbine: a valve
member blocks fluid communication between said compressor-outlet
inlet port and said heat-exchanger cold-stream inlet outlet
port.
2. The gas-turbine of claim 1, wherein said fifth port comprises a
compressor-inlet outlet port in fluid communication with an inlet
of said compressor, wherein during inverse Brayton-cycle operation
of the gas-turbine, a valve member blocks fluid communication
between said ambient inlet port and said compressor-inlet outlet
port.
3. The gas-turbine of claim 2, further comprising an additional
valve functionally associated with a hot-stream outlet of said
heat-exchanger, wherein during inverse Brayton-cycle operation of
the gas-turbine, said additional valve allows fluid communication
from said hot-stream outlet of said heat-exchanger to an inlet of
said compressor.
4. The gas-turbine of claim 3, wherein during Brayton-cycle
operation of the gas-turbine, said additional valve allows fluid
communication from said hot-stream outlet of said heat-exchanger to
an exhaust outlet of the gas-turbine.
5. The gas-turbine of claim 1, wherein said fifth port comprises a
heat-exchanger hot-stream outlet inlet port in fluid communication
with a hot-stream outlet of said heat-exchanger, and wherein during
inverse Brayton-cycle operation of the gas-turbine, a valve member
blocks fluid communication between said heat-exchanger hot-stream
outlet inlet port and said exhaust outlet port.
6. The gas-turbine of claim 5, further comprising an additional
valve functionally associated with a hot-stream outlet of said
heat-exchanger, wherein during inverse Brayton-cycle operation of
the gas-turbine, said additional valve allows fluid communication
from said hot-stream outlet of said heat-exchanger to an inlet of
said compressor.
7. The gas-turbine of claim 6, wherein during Brayton-cycle
operation of the gas-turbine, said additional valve allows fluid
communication from ambient to an inlet of said compressor.
8. The gas-turbine of claim 1, wherein said fifth port comprises a
compressor-inlet outlet port in fluid communication with an inlet
of said compressor, and wherein during inverse Brayton-cycle
operation of the gas-turbine a valve member blocks fluid
communication between said ambient inlet port and said
compressor-inlet outlet port; and said multiport valve further
includes a sixth port, a heat-exchanger hot-stream outlet inlet
port in fluid communication with a hot-stream outlet of said
heat-exchanger.
9. The gas-turbine of claim 8, further comprising an additional
valve functionally associated with a hot-stream outlet of said
heat-exchanger, wherein during inverse Brayton-cycle operation of
the gas-turbine, said additional valve allows fluid communication
from said hot-stream outlet of said heat-exchanger to an inlet of
said compressor.
10. The gas-turbine of claim 9, wherein during Brayton-cycle
operation of the gas-turbine, said additional valve allows fluid
communication from said hot-stream outlet of a heat-exchanger to an
exhaust outlet of the gas-turbine through said heat-exchanger
hot-stream outlet inlet port.
11. The gas-turbine of claim 8, further comprising a component
functionally associated with said heat-exchanger hot-stream outlet
inlet port, allowing flow of fluid from said hot-stream outlet of
said heat-exchanger through said heat-exchanger hot-stream outlet
inlet port and blocking flow of fluid from said multiport valve to
said hot-stream outlet of said heat-exchanger through said
heat-exchanger hot-stream outlet inlet port.
12. The gas-turbine of claim 11, wherein said component comprises a
undirectional valve that is part of said multiport valve.
13. The gas-turbine of claim 8, said multiport valve further
comprising a bypass conduit providing fluid communication between
said heat-exchanger hot-stream outlet inlet port and said
compressor-inlet outlet port, and wherein during Brayton-cycle
operation of the gas-turbine, a said valve member blocks said fluid
communication between said heat-exchanger hot-stream outlet inlet
port and said compressor-inlet outlet port through said bypass
conduit.
14. A multiport valve suitable for use with a gas-turbine allowing
switching of a mode of gas-turbine operation between a Brayton
cycle and an inverse Brayton cycle, comprising: a) a valve body
defining a void in the form of a plurality of fluid conduits; b) at
least five ports leading to said void comprising: a
compressor-outlet inlet port, an ambient inlet port, a
heat-exchanger cold-stream inlet outlet port, an exhaust outlet
port and a fifth port; c) a first valve member inside said valve
body movable between at least two positions, a first position and a
second position; and d) a second valve member inside said valve
body movable between at least two positions, a first position and a
second position, where a position of said first valve member and a
position of said second valve member together define fluid
communication between said inlet ports and said outlet ports
through said void.
15. The valve of claim 14, said first valve member and said second
valve member configured to cooperatively move between said first
positions and said second positions.
16. The valve of claim 14, said first valve member and said second
valve member configured to move independently between said first
positions and said second positions.
17. The valve of claim 14, wherein: said first valve member in said
first position blocks fluid communication between said ambient
inlet port and said heat-exchanger cold-stream inlet outlet port
and in said second position blocks fluid communication between said
ambient inlet port and said fifth port, a compressor inlet outlet
port; and said second valve member in said first position blocks
fluid communication between said compressor-outlet inlet port and
said exhaust outlet port and in said second position blocks fluid
communication between said compressor-outlet inlet port and said
heat-exchanger cold-stream inlet outlet port.
18. The valve of claim 14, wherein: said first valve member in said
first position blocks fluid communication between said
compressor-outlet inlet port and said exhaust outlet port and in
said second position blocks fluid communication between said fifth
port, a heat-exchanger hot-stream outlet inlet port, and said
exhaust outlet port; and said second valve member in said first
position blocks fluid communication between said ambient inlet port
and said heat-exchanger cold-stream inlet outlet port and in said
second position blocks fluid communication between said
compressor-outlet inlet port and said heat-exchanger cold-stream
inlet outlet port.
19. The valve of claim 14, wherein: said first valve member in said
first position blocks fluid communication between said ambient
inlet port and said heat-exchanger cold-stream inlet outlet port
and in said second position blocks fluid communication between said
ambient inlet port and said fifth port, a compressor inlet outlet
port and said second valve member in said first position blocks
fluid communication between a sixth port, a heat-exchanger
hot-stream outlet inlet port, and said heat-exchanger cold-stream
inlet outlet port and in said second position blocks fluid
communication between said compressor-outlet inlet port and said
heat-exchanger cold-stream inlet outlet port.
20. The valve of claim 19, further comprising a component
functionally associated with said heat-exchanger hot-stream outlet
inlet port, allowing flow of fluid into said void through said
heat-exchanger hot-stream outlet inlet port and blocking flow of
fluid from said void out through said heat-exchanger hot-stream
outlet inlet port.
21. The valve of claim 20, wherein said component comprises a
unidirectional valve.
22. The valve of claim 19, further comprising a bypass conduit
providing fluid communication between said heat-exchanger
hot-stream outlet inlet port and said compressor inlet outlet port,
and a third valve member inside said valve body movable between at
least two positions, a first position and a second position,
wherein in said first position said third valve member blocks fluid
communication between said heat-exchanger hot-stream outlet inlet
port and said compressor inlet outlet port through said bypass
conduit; and in said second position said third valve member blocks
fluid communication between said heat-exchanger hot-stream outlet
inlet port and said exhaust outlet port.
23. The valve of claim 22, said first valve member, said second
valve member and said third valve member configured to
cooperatively move between said first positions and said second
positions.
24. The valve of claim 22, wherein at least one of said first valve
member, said second valve member and said third valve member is
configured to move between said first position and said second
position independently of at least one other said valve member.
25. The valve of claim 14, wherein at least one of said valve
members is movable to at least one intermediate position between a
respective said first position and respective said second position,
thereby allowing fluid communication between a said inlet port and
at least two said outlet ports.
26. The valve of claim 14, wherein at least one valve member is
fashioned as an airfoil having an aerodynamic profile.
27. The valve of claim 25, wherein said second valve member is
movable to at least one said intermediate position, providing fluid
communication between said compressor-outlet inlet port and said
heat-exchanger cold-stream inlet outlet port and said exhaust
outlet port.
28. The valve of claim 25, wherein said first valve member is
movable to a said intermediate position, providing fluid
communication between said ambient inlet port and said
heat-exchanger cold-stream inlet outlet port and a compressor
outlet port.
29. The valve of claim 25, comprising a said third valve member,
wherein said third valve member is movable to a said intermediate
position, providing fluid communication between a heat-exchanger
hot-stream outlet inlet port and said exhaust outlet port and a
compressor-inlet outlet port.
30. The valve of claim 14, wherein at least one valve member is
configured to vary a size of a fluid path between a said inlet port
and a outlet port while said valve member in a said first position
and/or a second position.
31. The valve of claim 30, wherein said second valve member is
configured to vary a size of a fluid path between said
compressor-outlet inlet port and said heat-exchanger cold-stream
inlet outlet port when in said first position.
32. The valve of claim 30, wherein said first valve member is
configured to vary a size of a fluid path between said ambient
inlet port and said heat-exchanger cold-stream inlet outlet port
when in said second position.
33. The valve of claim 30, further comprising an additional valve
member movable inside said valve body and configured to vary a size
of a fluid path between said compressor-outlet inlet port and said
heat-exchanger cold-stream inlet outlet port.
34. The valve of claim 14, further comprising an additional valve
member movable inside said valve body and configured to vary a size
of a fluid path between said ambient inlet port and said
heat-exchanger cold-stream inlet outlet port.
35. The valve of claim 14, further comprising a permeable section
between a first region and a second region of said void, providing
fluid communication between said first region and said second
region.
36. The valve of claim 35, wherein said permeable section is
unidirectional, allowing passage of fluid from said first region to
said second region, and blocking passage of fluid from said second
region to said first region.
37. A gas-turbine configured to switch between a high-pressure
operation mode according to a Brayton cycle and a low-pressure
operation mode according to an inverse Brayton cycle, comprising a
valve of claim 14.
38. The gas-turbine of claim 37, further configured to switch to an
intermediate pressure mode between said high-pressure operation
mode and said low-pressure operation mode.
39. A method of operating a gas-turbine according to an inverse
Brayton cycle, comprising: a. providing a conduit allowing fluid
communication between a compressor of the gas-turbine and a
cold-stream inlet of a heat-exchanger of the gas-turbine; and b.
during inverse Brayton cycle operation of the gas-turbine,
directing fluid from said compressor to said heat-exchanger
cold-stream inlet through said conduit so that a portion of the
fluid entering said heat-exchanger cold-stream inlet is from said
compressor.
40. The method of claim 39, further comprising: adjusting a size of
said conduit so as to control an amount of fluid entering said
cold-stream inlet from said compressor.
41. The method of claim 39, wherein between about 30% and about 70%
by mass of the fluid entering the cold-stream inlet is from said
compressor.
42. A gas-turbine comprising, when operating according to an
inverse Brayton cycle, a. an air inlet configured to direct fluid
into a cold-stream conduit of a heat-exchanger through a
cold-stream inlet; b. conduits to direct fluid from said
cold-stream conduit to a combustor, from said combustor to a
turbine, from said turbine to a hot-stream conduit of said
heat-exchanger, from said hot-stream conduit to a compressor, and
from said compressor to an exhaust outlet; and c. a conduit
allowing passage of fluid from said compressor into said
cold-stream inlet of said heat-exchanger.
43. The gas-turbine of claim 42, wherein said conduit allowing
passage of fluid from said compressor into said cold-stream inlet
is of fixed size.
44. The gas-turbine of claim 42, wherein a size of said conduit
allowing passage of fluid from said compressor into said
cold-stream inlet is adjustable.
45. The gas-turbine of claim 42, wherein said conduit allowing
passage of fluid from said compressor into said cold-stream inlet
is configured so that during operation of the gas-turbine according
to an inverse Brayton cycle between about 30% and about 70% by mass
of the fluid entering said cold-stream inlet is from said
compressor.
Description
RELATED APPLICATION
[0001] The present application gains priority from U.S. Provisional
Patent Application No. 61/116,394 filed 20 Nov. 2008 which is
included by reference as if fully set forth herein.
FIELD AND BACKGROUND OF THE INVENTION
[0002] The present invention, in some embodiments, relates to the
field of gas-turbines, and more particularly, but not exclusively,
to gas-turbines operable in both high-pressure (Brayton cycle) and
low-pressure (inverse Brayton cycle) modes. The present invention,
in some embodiments, relates to the field of gas-turbines, and more
particularly, but not exclusively, to gas-turbines operable in
low-pressure mode (inverse Brayton cycle).
[0003] Gas-turbines are known for being lightweight, reliable and
requiring little maintenance compared to alternative work-producing
motors, e.g. an internal combustion engine (ICE). Above all,
gas-turbines are known for efficiently converting chemical energy
stored in a combustible fuel to mechanical energy when working at
an optimum work point. However, in spite of their potential,
gas-turbines are currently not well known in applications requiring
work-producing motors--for example ground vehicles such as cars and
trucks--for several reasons.
[0004] One reason is that a given gas-turbine may generate a
certain power at high efficiency for a prescribed load, but is less
efficient at part load, particularly if turbine speed is
maintained. Many applications, vehicular applications in
particular, generally have changing power demands, for instance
requiring more power for rapid acceleration or climbing hills, and
requiring less power when driving in traffic.
[0005] A second reason is "turbine lag": it takes a noticeably long
time for a given gas-turbine to speed-up to produce more power,
e.g., for acceleration. Thus, if turbine speed is reduced when
power demand is low, a sudden increased power demand can be met
only after a noticeable time lag.
[0006] A third reason is that the lifetime of gas-turbines is
severely limited by startup/shutdown events. Unlike an ICE, it is
not practical to shut down a gas-turbine when idling.
[0007] A fourth reason is that the power requirements for many
applications, e.g. ground vehicles, are low compared to the power
gas-turbines efficiently produce. Although large gas-turbines are
relatively efficient, the efficiency of a gas-turbine decreases
with smaller size (less than 300 kW) for various reasons including
leakage around the periphery of the turbine which is increasingly
significant with smaller turbine size.
[0008] Commonly, gas-turbines are operated according to either a
high-pressure Brayton cycle or a low-pressure inverse Brayton
cycle. A gas-turbine operating according to the inverse Brayton
cycle efficiently produces less power than a similar-sized
gas-turbine operating according to the Brayton cycle. In FIG. 1A a
gas-turbine 2 in a typical Brayton cycle operation, and in FIG. 1B
a gas-turbine 4 in a typical inverse Brayton cycle operation, are
schematically depicted. Both gas-turbines 2 and 4 comprise a
compressor 20 and a turbine 22, together mounted on a common
rotatable shaft 24 constituting a spool, a combustor 26, an air
inlet 28 and an exhaust outlet 30. One end of shaft 24 constitutes
the rotor of a generator 32. Gas-turbines 2 or 4 and generator 32
together with other components such as a fuel-supply unit 34 and a
gas-turbine controller 36 constitute a power generation unit
38.
[0009] In typical high-pressure (Brayton-cycle) operation, FIG. 1A,
ambient air is drawn through air inlet 28 into a compressor inlet
(low-pressure port) 40, and forced by compressor 20 through a
compressor outlet (high-pressure port) 42 into a combustor inlet
44. In combustor 26, the air is mixed with fuel and the mixture
combusted. The hot exhaust gases resulting from the combustion are
directed through a combustor outlet 46 into a turbine inlet 48. The
hot exhaust gases expand through and rotate turbine 22,
consequently rotating shaft 24 and compressor 20 before exiting
turbine 22 through a turbine outlet 50, to be released to the
surroundings through exhaust outlet 30.
[0010] In typical low-pressure (inverse Brayton-cycle) operation,
FIG. 1B, ambient air is drawn into combustor 26 through air inlet
28 and through combustor inlet 44. In combustor 26 the air is mixed
with fuel and the mixture combusted. The hot exhaust gases
resulting from the combustion are directed into turbine 22 through
turbine inlet 48. The hot exhaust gases expand through and rotate
turbine 22, consequently rotating shaft 24 and compressor 20. The
hot exhaust gases are then drawn into compressor inlet 40 and
forced by compressor 20 through compressor outlet 42 and through
exhaust outlet 30 to be released to the surroundings.
[0011] In both the Brayton cycle and inverse Brayton cycle, the
rotation of shaft 24 by exhaust gases expanding through turbine 22
provides usable mechanical work, e.g. for generation of electric
power by generator 32.
[0012] Gas-turbines such as 2 or 4 typically include gas-turbine
controller 36 that monitors and controls the gas-turbine, including
by regulating the amount of fuel supplied to combustor 26 by
fuel-supply unit 34.
[0013] To increase thermal efficiency, gas-turbines such as 2 or 4
typically include a heat-exchanger 52, such as a recuperator or
regenerator. Heat-exchanger 52 includes a cold-stream conduit 54
and a hot-stream conduit 56, both having inlets 58 and 60,
respectively, and outlets 62 and 64, respectively. Heat-exchanger
52 increases the thermal efficiency of a gas-turbine by recovering
heat from hot exhaust gases passing through hot-stream conduit 56
to preheat air passing through cold-stream conduit 54 prior to
entering combustor 26.
[0014] In U.S. Pat. Nos. 6,526,757 and 6,606,864 both of McKay are
provided multipressure mode gas-turbines, gas-turbines with valving
having two configurations. In a first valving configuration the
gas-turbine operates in a high-pressure mode according to a Brayton
cycle. In a second valving configuration the gas-turbine operates
in a low-pressure mode according to an inverse Brayton cycle. The
gas-turbine is toggled between the two modes by the synchronized
switching of a plurality of valves between the two valving
configurations changing the pressure and therefore the mass flow
through the gas-turbine while maintaining a constant temperature
and shaft speed, allowing two substantially equally efficient power
outputs, where the power output during low-pressure mode operation
is less than during high-pressure mode operation.
SUMMARY OF THE INVENTION
[0015] Aspects of the invention relate to valves suitable for use
with gas-turbines that, in some embodiments, allow switching
between high-pressure and low-pressure operation modes of a
gas-turbine. Aspects of the invention relate to gas-turbines that
are configured to operate in both high-pressure and low-pressure
modes.
[0016] Aspects of the invention relate to valves suitable for use
with gas-turbines that, in some embodiments, allow switching
between high-pressure, low-pressure and intermediate-pressure
operation modes of a gas-turbine. Aspects of the invention relate
to gas-turbines that are configured to operate in high-pressure,
low-pressure and intermediate-pressure modes.
[0017] Aspects of the invention relate to valves that allow simple
and efficient varying of the pressure and power output of a
gas-turbine, that in some embodiments is substantially continuous.
Aspects of the invention relate to gas-turbines that are configured
to efficiently operate in different pressure modes, allowing
different power outputs at substantially similar efficiencies.
[0018] According to an aspect of some embodiments of the invention,
there is provided a gas-turbine configured for operation according
to both Brayton-cycle and inverse-Brayton cycle, comprising:
[0019] a) a multiport valve including movable valve members and at
least five ports of which at least two inlet ports and at least two
outlet ports: a compressor-outlet inlet port, an ambient inlet
port, a heat-exchanger cold-stream inlet outlet port, an exhaust
outlet port, and a fifth port;
[0020] b) a compressor-outlet of a compressor of the gas-turbine in
fluid communication with the compressor-outlet inlet port; and
[0021] c) a heat-exchanger cold-stream inlet of a heat-exchanger of
the gas-turbine in fluid communication with the heat-exchanger
cold-stream inlet outlet port; [0022] wherein during Brayton-cycle
operation of the gas-turbine, [0023] a valve member blocks fluid
communication between the compressor-outlet inlet port and the
exhaust outlet port, and [0024] a valve member blocks fluid
communication between the ambient inlet port and the heat-exchanger
cold-stream inlet outlet port; [0025] and [0026] during inverse
Brayton-cycle operation of the gas-turbine, [0027] a valve member
blocks fluid communication between the compressor-outlet inlet port
and the heat-exchanger cold-stream inlet outlet port.
[0028] According to an aspect of some embodiments of the invention
there is also provided a multiport valve suitable for use with a
gas-turbine and allowing switching the mode of operation of a
gas-turbine between a high-pressure mode according to a Brayton
cycle and a low-pressure mode according to an inverse Brayton
cycle, the valve comprising:
[0029] a) a valve body defining a void in the form of a plurality
of fluid conduits;
[0030] b) at least five ports leading to the void of which at least
two inlet ports and at least two outlet ports: a compressor-outlet
inlet port, an ambient inlet port, a heat-exchanger cold-stream
inlet outlet port, an exhaust outlet port and a fifth port;
[0031] c) a first valve member inside the valve body movable
between at least two positions, a first position and a second
position; and
[0032] d) a second valve member inside the valve body movable
between at least two positions, a first position and a second
position.
[0033] where the position of the first valve member and the
position of the second valve member (together) define fluid
communication between the inlet ports and the outlet ports through
the void.
[0034] According to an aspect of some embodiments of the invention,
there is also provided a gas-turbine, configured to switch between
a high-pressure operation mode according to a Brayton cycle and a
low-pressure operation mode according to an inverse Brayton cycle,
comprising a multiport valve as described herein. In some
embodiments, the gas-turbine is also configured to switch to an
intermediate pressure mode between the high-pressure operation mode
and the low-pressure operation mode.
[0035] Aspects of the invention relate to gas-turbines operating in
low-pressure mode that have reduced NOx emissions. Thus, according
to an aspect of some embodiments of the invention, there is also
provided a method of operating a gas-turbine according to an
inverse Brayton cycle, comprising:
[0036] a) providing a conduit allowing fluid communication between
a compressor of the gas-turbine and a cold-stream inlet of a
heat-exchanger of the gas-turbine; and
[0037] b) during inverse Brayton cycle operation of the
gas-turbine, directing fluid from the compressor to the
heat-exchanger cold-stream inlet through the conduit so that a
portion of the fluid entering the heat-exchanger cold-stream inlet
is from the compressor. As a result, inlet air is mixed with a
portion of the oxygen-depleted exhaust from the compressor,
decreasing oxygen content of the combustible mixture in the
combustor, reducing the amount of NOx produced in the combustor and
emitted by the gas-turbine.
[0038] According to an aspect of some embodiments of the invention,
there is also provided a gas-turbine comprising, when operating
according to an inverse Brayton cycle,
[0039] a) an air inlet configured to direct fluid into a
cold-stream conduit of a heat-exchanger through a cold-stream
inlet;
[0040] b) conduits to direct fluid from the cold-stream conduit to
a combustor, from the combustor to a turbine, from the turbine to a
hot-stream conduit of the heat-exchanger, from the hot-stream
conduit to a compressor, and from the compressor to an exhaust
outlet port; and
[0041] c) a conduit allowing passage of fluid from the compressor
into the cold-stream inlet of the heat-exchanger. In some
embodiments, the gas-turbine is configured to operate only
according to the inverse Brayton cycle. In some embodiments, the
gas-turbine is a multi-power gas-turbine configured to operate
according to both the Brayton cycle and the inverse Brayton
cycle.
[0042] According to an aspect of some embodiments of the invention,
there is also provided a motor vehicle (e.g., an automobile, a
light truck, a truck, a bus) comprising a gas-turbine substantially
as described herein.
[0043] As used herein, the term "high-pressure mode" refers to
operation of a gas-turbine where compressor inlet pressure is close
to atmospheric (.about.1.times. ambient) and compressor outlet
(exhaust) pressure is superatmospheric (typically .about.3.times.
ambient pressure).
[0044] As used herein, the term "low-pressure mode" refers to
operation of a gas-turbine where compressor inlet pressure is
subatmospheric (.about.0.3.times. ambient pressure) and compressor
outlet (exhaust) pressure is close to atmospheric (.about.1.times.
ambient pressure).
[0045] As used herein, the term "intermediate pressure mode" refers
to operation of a gas-turbine where compressor inlet pressure is
subatmospheric (between above 0.3.times. ambient pressure to
.about.1.times. ambient pressure) and compressor outlet (exhaust)
pressure is higher than atmospheric (between above 1.times. ambient
pressure to .about.3.times. ambient pressure).
[0046] Unless otherwise defined, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which this invention pertains. In case
of conflict, the patent specification, including definitions, will
control.
[0047] As used herein, the terms "comprising", "including",
"having" and grammatical variants thereof are to be taken as
specifying the stated features, integers, steps or components but
do not preclude the addition of one or more additional features,
integers, steps, components or groups thereof. These terms
encompass the terms "consisting of" and "consisting essentially
of".
[0048] As used herein, the indefinite articles "a" and "an" mean
"at least one" or "one or more" unless the context clearly dictates
otherwise.
BRIEF DESCRIPTION OF THE FIGURES
[0049] Some embodiments of the invention are described herein, with
reference to the accompanying figures The description, together
with the figures, makes apparent how embodiments of the invention
may be practiced to a person having ordinary skill in the art. The
figures are for the purpose of illustrative discussion of
embodiments of the invention and no attempt is made to show
structural details of an embodiment in more detail than is
necessary for a fundamental understanding of the invention. For the
sake of clarity, objects depicted in the figures are not drawn to
scale.
[0050] In the Figures:
[0051] FIGS. 1A and 1B are schematic depictions of a Brayton cycle
gas-turbine (1A) and an inverse Brayton cycle gas-turbine (1B);
[0052] FIGS. 2A and 2B are schematic depictions of an embodiment of
a 5-port valve suitable for use with a gas-turbine in two
configurations allowing the gas-turbine to operate in a
high-pressure operation mode and in a low-pressure operation mode,
respectively;
[0053] FIGS. 3A and 3B are schematic depictions of an embodiment of
a gas-turbine including an embodiment of a 5-port valve of FIG. 2
where the valve is in two configurations so that the gas-turbine
operates in a high-pressure operation mode and in a low-pressure
operation mode, respectively;
[0054] FIG. 4 is of a conceptual graph qualitatively showing
thermal efficiency as a function of power output of various
embodiments of gas-turbines described herein;
[0055] FIGS. 5A and 5B are schematic depictions of an embodiment of
a gas-turbine including an embodiment of a 5-port valve where the
valve is in two configurations allowing the gas-turbine to operate
in a high-pressure operation mode and in a low-pressure operation
mode, respectively;
[0056] FIGS. 6A and 6B are schematic depictions of an embodiment of
a 6-port valve suitable for use with a gas-turbine in two
configurations allowing the gas-turbine to operate in a
high-pressure operation mode and in a low-pressure operation mode,
respectively;
[0057] FIGS. 7A and 7B are schematic depictions of an embodiment of
a gas-turbine including an embodiment of a 6-port valve of FIG. 6
where the valve is in two configurations so that the gas-turbine
operates in a high-pressure operation mode and in a low-pressure
operation mode, respectively;
[0058] FIGS. 8A and 8B are schematic depictions of an embodiment of
a 6-port valve suitable for use with a gas-turbine in two
configurations allowing the gas-turbine to operate in a
high-pressure operation mode and in a low-pressure operation mode,
respectively;
[0059] FIGS. 9A and 9B are schematic depictions of an embodiment of
a gas-turbine including an embodiment of a 6-port valve of FIG. 8
where the valve is in two configurations so that the gas-turbine
operates in a high-pressure operation mode and in a low-pressure
operation mode, respectively;
[0060] FIG. 10 is a schematic depiction of an embodiment of a valve
suitable for use with a gas-turbine, allowing the gas-turbine to
operate in at least one intermediate pressure operation mode in
addition to a low-pressure operation mode and a high-pressure
operation mode;
[0061] FIG. 11 is a schematic depiction of an embodiment of a
gas-turbine including an embodiment of a valve of FIG. 10, where
the valve is set so that the gas-turbine operates in an
intermediate pressure operation mode;
[0062] FIG. 12 is a schematic depiction of an embodiment of a
gas-turbine including an embodiment of a six-port valve similar to
the valve depicted in FIG. 10;
[0063] FIGS. 13A and 13B are schematic depictions of an embodiment
of a 5-port valve useful for continuously varying the mass flow to
the combustor of a gas-turbine in a high-pressure operation mode,
in high and low-mass flow rate configurations, respectively;
[0064] FIGS. 14A and 14B are schematic depictions of an embodiment
of a 5-port valve useful for continuously varying the mass flow to
the combustor of a gas-turbine in a low-pressure operation mode, in
high and low mass flow rate configurations, respectively;
[0065] FIGS. 15A, 15B and 15C are schematic depictions of
embodiments of valves useful for continuously varying the mass flow
to the combustor of a gas-turbine high and low-pressure operation
modes;
[0066] FIG. 16 is a gas-turbine including a valve suitable for
switching the gas-turbine between at least two pressure level
operation modes and useful for reducing NOx emissions of the
gas-turbine when in low-pressure operation mode; and
[0067] FIGS. 17A and 17B are two embodiments of a permeable section
in a multiport valve suitable for use in a gas turbine and useful
for reducing NOx emissions of the gas-turbine as described
herein.
DESCRIPTION OF SOME EMBODIMENTS OF THE INVENTION
[0068] Some embodiments of the invention relate to multiport valves
that allow switching between high-pressure operation (Brayton
cycle) and low-pressure operation (inverse Brayton cycle) modes of
a gas-turbine.
[0069] Some embodiments of the invention relate to multiport valves
that allow operation of a gas-turbine in high-pressure,
low-pressure and intermediate pressure modes.
[0070] Some embodiments of the invention relate to multiport valves
that allow operation of a gas-turbine at a variable power output in
high-pressure modes and/or low-pressure modes at relatively high
efficiency by varying the mass flow through the gas-turbine. Some
embodiments of the invention relate to valves that allow simple and
efficient varying of the pressure, mass flow and power output of a
gas-turbine, that in some embodiments is substantially
continuous.
[0071] Some embodiments of the invention relate to gas-turbines
operating in a low-pressure mode (inverse Brayton mode) having
reduced NOx emissions as well as valves useful for such
gas-turbines.
[0072] The principles, uses and implementations of the teachings of
the invention may be better understood with reference to the
accompanying description and Figures. Upon perusal of the
description and figures present herein, one skilled in the art is
able to implement the teachings of the invention without undue
effort or experimentation, including by consulting U.S. Pat. No.
6,526,757, which is included by reference as if fully set forth
herein. In the Figures, like reference numerals refer to like parts
throughout.
[0073] Before explaining at least one embodiment of the invention
in detail, it is to be understood that the invention is not
necessarily limited in its application to the details of
construction and the arrangement of the components and/or methods
set forth herein. The invention is capable of other embodiments or
of being practiced or carried out in various ways. The phraseology
and terminology employed herein are for descriptive purpose and
should not be regarded as limiting.
[0074] As noted in the introduction, in U.S. Pat. Nos. 6,526,757
and 6,606,864 are disclosed gas-turbines provided with valving that
allow the gas-turbines to switch between high-pressure operation
with efficient high-power output and low-pressure operation with
efficient low-power output. However, a problem with the
gas-turbines as described in U.S. Pat. Nos. 6,526,757 and 6,606,864
is that of complexity: the valving system of a simplest embodiment
includes six separate on-off valves that must be operated
synchronously to toggle between the two modes. Furthermore, in
order to achieve additional, intermediate pressure--and thus
intermediate power--turbine operation modes, even more complex
embodiments which include more than one spool and many separate
valves, must be employed.
[0075] It has been found that it is possible to simplify the
valving system necessary to allow a gas-turbine to switch between
high-pressure and low-pressure operation.
[0076] Thus, according to an aspect of some embodiments of the
invention, there is provided a gas-turbine configured to switch
between a high-pressure operation mode according to a Brayton cycle
and a low-pressure operation mode according to an inverse Brayton
cycle, comprising:
[0077] a) a multiport valve including movable valve members and at
least five ports of which at least two inlet ports and at least two
outlet ports: a compressor-outlet inlet port, an ambient inlet
port, a heat-exchanger cold-stream inlet outlet port, an exhaust
outlet port, and a fifth port;
[0078] b) a compressor outlet of a compressor of the gas-turbine in
fluid communication with the compressor-outlet inlet port; and
[0079] c) a heat-exchanger cold-stream inlet of a heat-exchanger of
the gas-turbine in fluid communication with the heat-exchanger
cold-stream inlet outlet port;
wherein during Brayton-cycle operation of the gas-turbine, a valve
member blocks fluid communication between the compressor-outlet
inlet port and the exhaust outlet port and a valve member blocks
fluid communication between the ambient inlet port and the
heat-exchanger cold-stream inlet outlet port; and during inverse
Brayton-cycle operation of the gas-turbine, a valve member blocks
fluid communication between the compressor-outlet inlet port and
the heat-exchanger cold-stream inlet outlet port.
[0080] In some embodiments, the fifth port is a compressor-inlet
outlet port in fluid communication with an inlet of the compressor
of the gas-turbine, and during inverse Brayton-cycle operation of
the gas-turbine, a valve member blocks fluid communication between
the ambient inlet port and the compressor-inlet outlet port. In
some such embodiments, the gas-turbine further comprises an
additional valve functionally associated with the hot-stream outlet
of the heat-exchanger, wherein during inverse Brayton-cycle
operation of the gas-turbine, the additional valve allows fluid
communication from the hot-stream outlet of the heat-exchanger to
an inlet of the compressor. In some such embodiments, during
Brayton-cycle operation of the gas-turbine, the additional valve
allows fluid communication from the hot-stream outlet of the
heat-exchanger to an exhaust outlet of the gas-turbine. An
exemplary such embodiment is depicted in FIGS. 3A and 3B.
[0081] In some embodiments, the fifth port is a heat-exchanger
hot-stream outlet inlet port in fluid communication with a
hot-stream outlet of the heat-exchanger of the gas-turbine, and
during inverse Brayton-cycle operation of the gas-turbine, a valve
member blocks fluid communication between the heat-exchanger
hot-stream outlet inlet port and the exhaust outlet port. In some
such embodiments, the gas-turbine further comprises an additional
valve functionally associated with a hot-stream outlet of the
heat-exchanger of the gas-turbine, and during inverse Brayton-cycle
operation of the gas-turbine, the additional valve allows fluid
communication from the hot-stream outlet of the heat-exchanger to
an inlet of the compressor. In some embodiments, during
Brayton-cycle operation of the gas-turbine, the additional valve
allows fluid communication from ambient to an inlet of the
compressor. An exemplary such embodiment is depicted in FIGS. 5A
and 5B.
[0082] In some embodiments, the multiport valve includes six ports,
of which three are inlet ports and three are outlet ports.
[0083] In some such embodiments where the multiport valve includes
six ports, the fifth port is a compressor-inlet outlet port in
fluid communication with an inlet of the compressor, and during
inverse Brayton-cycle operation of the gas-turbine a valve member
blocks fluid communication between the ambient inlet port and the
compressor-inlet outlet port; and the multiport valve further
includes a sixth port, a heat-exchanger hot-stream outlet inlet
port in fluid communication with a hot-stream outlet of the
heat-exchanger of the gas-turbine.
[0084] In some embodiments including such a six-port valve, the
gas-turbine further comprises an additional valve functionally
associated with a hot-stream outlet of the heat-exchanger of the
gas-turbine, and during inverse Brayton-cycle operation of the
gas-turbine, the additional valve allows fluid communication from
the hot-stream outlet of the heat-exchanger of the gas-turbine to
an inlet of the compressor of the gas-turbine. In some such
embodiments, during Brayton-cycle operation of the gas-turbine, the
additional valve allows fluid communication from the hot-stream
outlet of the heat-exchanger of the gas-turbine to an exhaust
outlet of the gas-turbine through the heat-exchanger hot-stream
outlet inlet port. In some such embodiments, the gas-turbine
further comprises a component functionally associated with the
heat-exchanger hot-stream outlet inlet port, allowing flow of fluid
from the hot-stream outlet of the heat-exchanger through the
heat-exchanger hot-stream outlet inlet port and blocking flow of
fluid from the multiport valve to the hot-stream outlet of the
heat-exchanger through the heat-exchanger hot-stream outlet inlet
port. In some such embodiments, the component is a undirectional
valve that is part of the multiport valve. An exemplary such
embodiment is depicted in FIGS. 7A and 7B.
[0085] In some such embodiments where the multiport valve includes
six ports, the multiport valve further comprising a bypass conduit
bypassing the valve void, providing fluid communication between the
heat-exchanger hot-stream outlet inlet port and the
compressor-inlet outlet port, wherein during Brayton-cycle
operation of the gas-turbine, a valve member blocks the fluid
communication between the heat-exchanger hot-stream outlet inlet
port and the compressor-inlet outlet port through the bypass
conduit. An exemplary such embodiment is depicted in FIGS. 9A and
9B.
[0086] According to an aspect of some embodiments of the invention
there is also provided a multiport valve suitable for use with a
gas-turbine and allowing switching the mode of operation of a
gas-turbine between a high-pressure mode according to a Brayton
cycle and a low-pressure mode according to an inverse Brayton
cycle, the valve comprising:
[0087] a) a valve body defining a void in the form of a plurality
of fluid conduits;
[0088] b) at least five ports leading to the void of which at least
two inlet ports and at least two outlet ports: a compressor-outlet
inlet port, an ambient inlet port, a heat-exchanger cold-stream
inlet outlet port, an exhaust outlet port and a fifth port;
[0089] c) a first valve member inside the valve body movable
between at least two positions, a first position and a second
position; and
[0090] d) a second valve member inside the valve body movable
between at least two positions, a first position and a second
position
where the position of the first valve member and the position of
the second valve member (together) define fluid communication
between the inlet ports and the outlet ports through the void.
[0091] In some embodiments, the first valve member and the second
valve member are configured to cooperatively move between the first
positions and the second positions. In some embodiments, the first
valve member and the second valve member are configured to move
independently between the first positions and the second
positions.
[0092] In some embodiments, in the first position the first valve
member is in contact with a first valve seat and in the second
position in contact with a second valve seat. In some embodiments,
in the first position the second valve member is in contact with a
third valve seat and in the second position in contact with a third
valve seat.
[0093] As detailed hereinbelow, in some embodiments, in a first or
second position a given valve member blocks fluid communication
between specific ports. By blocking fluid communication is meant
that the fluid communication between the ports is blocked to a
sufficient degree to achieve the desired purpose (e.g., operating
an associated gas-turbine in a desired mode), although there may be
some leakage, for example as described below. As detailed
hereinbelow, in some embodiments, in a first or second position a
given valve member contacts a specific valve seat. By contacting a
valve seat is meant contacting to a sufficient degree to achieve a
desired purpose as described immediately herein above, for example,
in some embodiments is meant "sealing contact".
[0094] In some embodiments, the first valve member in the first
position blocks fluid communication (through the void) between the
ambient inlet port and the heat-exchanger cold-stream inlet outlet
port and in the second position blocks fluid communication (through
the void) between the ambient inlet port and the fifth port, a
compressor inlet outlet port; and the second valve member in the
first position blocks fluid communication (through the void)
between the compressor-outlet inlet port and the exhaust outlet
port and in the second position blocks fluid communication (through
the void) between the compressor-outlet inlet port and the
heat-exchanger cold-stream inlet outlet port. An exemplary such
embodiment is valve 100 depicted in FIGS. 2 and 3.
[0095] In some embodiments, the first valve member in the first
position blocks fluid communication (through the void) between the
compressor-outlet inlet port and the exhaust outlet port and in the
second position blocks fluid communication (through the void)
between the fifth port, a heat-exchanger hot-stream outlet inlet
port, and the exhaust outlet port; and the second valve member in
the first position blocks fluid communication (through the void)
between the ambient inlet port and the heat-exchanger cold-stream
inlet outlet port and in the second position blocks fluid
communication (through the void) between the compressor-outlet
inlet port and the heat-exchanger cold-stream inlet outlet port. An
exemplary such embodiment is depicted in FIG. 5.
[0096] In some embodiments, the first valve member in the first
position blocks fluid communication (through the void) between the
ambient inlet port and the heat-exchanger cold-stream inlet outlet
port and in the second position blocks fluid communication (through
the void) between the ambient inlet port and the fifth port, a
compressor inlet outlet port; and the second valve member in the
first position blocks fluid communication (through the void)
between a sixth port, a heat-exchanger hot-stream outlet inlet
port, and the heat-exchanger cold-stream inlet outlet port and in
the second position blocks fluid communication (through the void)
between the compressor-outlet inlet port and the heat-exchanger
cold-stream inlet outlet port. An exemplary such embodiment is
depicted in FIGS. 6 and 7. In some embodiments, the valve further
comprises a component functionally associated with the
heat-exchanger hot-stream outlet inlet port, allowing flow of fluid
into the void through the heat-exchanger hot-stream outlet inlet
port and blocking flow of fluid from the void out through the
heat-exchanger hot-stream outlet inlet port. In some such
embodiments the component is a unidirectional valve (e.g., a check
valve, in some embodiments located inside the valve body)
configured to allow fluid to flow into the void of the valve body
through the heat-exchanger hot-stream outlet inlet port but to
block the flow of fluid from the valve body out through the
heat-exchanger hot-stream outlet inlet port.
[0097] In some embodiments, the valve further comprises a bypass
conduit providing fluid communication bypassing the valve void
between the heat-exchanger hot-stream outlet inlet port and the
compressor inlet outlet port, and a third valve member inside the
valve body movable between at least two positions, a first position
and a second position, wherein in the first position the third
valve member blocks fluid communication through the bypass conduit
between the heat-exchanger hot-stream outlet inlet port and the
compressor inlet outlet port through the bypass conduit and in the
second position the third valve member blocks fluid communication
through the void between the heat-exchanger hot-stream outlet inlet
port and the exhaust outlet port. In some embodiments, in the first
position the third valve member is in contact with a fifth valve
seat and in the second position the third valve member is in
contact with a sixth valve seat. An exemplary such embodiment is
depicted in FIG. 8. In some such embodiments, the first valve
member, the second valve member and the third valve member are
configured to cooperatively move between the first positions and
the second positions. In some such embodiments, at least one of the
first valve member, the second valve member and the third valve
member is configured to move between the first position and the
second position independently of at least one other of the valve
members.
[0098] In some embodiments of the multiport valve at least one of
the valve members is movable to at least one intermediate position
between a respective first position and respective second position,
thereby allowing fluid communication (through the void) between an
inlet port and at least two outlet ports. In some such embodiments,
at least one valve member is fashioned as an airfoil having an
aerodynamic profile (generally predefined aerodynamic profile)
configured to direct the flow of fluid as desired through the fluid
conduits of the valve body.
[0099] In some embodiments, the second valve member is movable to
at least one intermediate position, providing fluid communication
(through the void) between the compressor-outlet inlet port and the
heat-exchanger cold-stream inlet outlet port and the exhaust outlet
port. Exemplary such embodiments include valve 100, valve 102 and
valve 103 depicted in FIGS. 10 and 11. In some such embodiments,
the second valve member is movable to a plurality of such
intermediate positions, allowing variation of the relative size of
the path between the compressor-outlet inlet port and the
heat-exchanger cold-stream inlet outlet port to the relative size
of the path between the compressor-outlet inlet port and the
exhaust outlet port.
[0100] In some embodiments, the first valve member is movable to an
intermediate position, providing fluid communication between the
ambient inlet port and the heat-exchanger cold-stream inlet outlet
port and the compressor-inlet outlet port. Exemplary such
embodiments include valve 100, valve 102 and valve 103 depicted in
FIGS. 10 and 11. In some such embodiments, the first valve member
is movable to a plurality of such intermediate positions, allowing
variation of the relative size of the path between the ambient
inlet port and the heat-exchanger cold-stream inlet outlet port to
the relative size of the path between the ambient inlet port and
the compressor inlet outlet port.
[0101] In some embodiments comprising a third valve member, the
third valve member is movable to an intermediate position,
providing fluid communication between the heat-exchanger hot-stream
outlet inlet port and the exhaust outlet port and the
compressor-inlet outlet port. An exemplary such embodiment is valve
103 depicted in FIGS. 10 and 11. In some such embodiments, the
third valve member is movable to a plurality of such intermediate
positions, allowing variation of the relative size of the path
between the heat-exchanger hot-stream outlet inlet port and the
exhaust outlet port to the relative size of the path between the
heat-exchanger hot-stream outlet inlet port and the
compressor-inlet outlet port.
[0102] In some embodiments, at least one valve member is configured
to vary a size of a fluid path between an inlet port and an outlet
port while the valve member in the first position and/or the second
position.
[0103] In some embodiments, the second valve member is configured
to vary a size of a fluid path between the compressor-outlet inlet
port and the heat-exchanger cold-stream inlet outlet port when in
the first position. An exemplary such embodiment is depicted in
FIG. 13.
[0104] In some embodiments, the first valve member is configured to
vary a size of a fluid path between the ambient inlet port and the
heat-exchanger cold-stream inlet outlet port when in the second
position. An exemplary such embodiment is depicted in FIG. 14.
[0105] In some embodiments, the multiport valve further comprises
an additional valve member movable inside the valve body and, the
additional valve member configured to vary a size of a fluid path
between the compressor-outlet inlet port and the heat-exchanger
cold-stream inlet outlet port. An exemplary such embodiment is
depicted in FIGS. 15A and 15C.
[0106] In some embodiments, the multiport valve further comprises
an additional valve member movable inside the valve body and
configured to vary a size of a fluid path between the ambient inlet
port and the heat-exchanger cold-stream inlet outlet port. An
exemplary such embodiment is depicted in FIGS. 15B and 15C.
[0107] In some embodiments, the valve further comprises a permeable
section between a first region and a second region of the void in
the valve body, providing fluid communication between the first
region and the second region. Such a permeable section may be
implemented in any suitable way including a conduit, slits, pores
and the like. The utility of such a permeable section is described
hereinbelow. In some such embodiments, the first region is in
proximity of the exhaust outlet port and in some such embodiments
between the second valve member and the exhaust outlet port. In
some such embodiments, the second region is in proximity of the
heat-exchanger cold-steam inlet outlet port and in some such
embodiments between the second valve member and heat-exchanger
cold-stream inlet outlet port. In some such embodiments, the
permeable section is unidirectional, allowing passage of fluid from
the first region to the second region, and blocking passage of
fluid from the second region to the first region. Such a
unidirectional permeable section may be implemented in any suitable
way including with the help of a unidirectional valve, a check
valve (a unidirectional valve that functions automatically without
an external control, e.g. variants of a swing check valve or reed
valve) or a pump. In some embodiments, the permeable section is
part of the second valve member.
[0108] According to an aspect of some embodiments of the invention,
there is also provided a gas-turbine, configured to switch between
a high-pressure operation mode according to a Brayton cycle and a
low-pressure operation mode according to an inverse Brayton cycle,
comprising a multiport valve as described herein. In some
embodiments, the gas-turbine is also configured to switch to an
intermediate pressure mode between the high-pressure operation mode
and the low-pressure operation mode.
Embodiment of 5-Port Valve Suitable for Use with a Gas-Turbine
[0109] FIGS. 2A and 2B depict an embodiment of a valve 100,
suitable for use with a gas-turbine, in side cross-section. Valve
100 comprises a valve body 110 defining a single void in the form
of a plurality of fluid conduits 120. Valve 100 further includes
two inlet ports and three outlet ports: an ambient inlet port 151,
a compressor-outlet inlet port 152, a compressor-inlet outlet port
161, a heat-exchanger cold-stream inlet outlet port 162 and an
exhaust outlet port 163, the five ports in fluid communication one
with the other through fluid conduits 120. Valve 100 further
includes a first valve member 171 and a second valve member 181.
First valve member 171 is movable inside valve body 110 between at
least two positions: a first position, depicted in FIG. 2A, in
contact with a first valve seat 172 in valve body 110 blocking
fluid communication between ambient inlet port 151 and
heat-exchanger cold-stream inlet outlet port 162 and a second
position, depicted in FIG. 2B, in contact with a second valve seat
173 in valve body 110 blocking fluid communication between ambient
inlet port 151 and compressor-inlet outlet port 161. Second movable
valve member 181 is movable inside valve body 110 between at least
two positions: a first position, depicted in FIG. 2A, in contact
with a third valve seat 182 in valve body 110 blocking fluid
communication between compressor-outlet inlet port 152 and exhaust
outlet port 163 and a second position, depicted in FIG. 2B, in
contact with a fourth valve seat 183 in valve body 110 blocking
fluid communication between compressor-outlet inlet port 152 and
heat-exchanger cold-stream inlet outlet port 162.
[0110] First movable valve member 171 is movable between the first
and second positions by rotating around a first valve member axis
174. Second movable valve member 181 is movable between the first
and second positions by rotating around a second valve member axis
184.
[0111] When valve members 171 and 181 are in the respective first
position depicted in FIG. 2A (configuration "1"), valve 100 allows
an associated gas-turbine to operate in high-pressure operation
mode, as is described further below. When valve members 171 and 181
are in the respective second position depicted in FIG. 2B
(configuration "2"), valve 100 allows an associated gas-turbine to
operate in low-pressure operation mode.
[0112] In some embodiments, valve members 171 and 181 are
configured for cooperative movement, that is to say both valve
members move together between the first position (FIG. 2A) and the
second position (FIG. 2B). In some embodiments, valve members 171
and 181 are independently operable. For example, in such
embodiments valve member 171 may be in contact with first valve
seat 172 (first position, FIG. 2A), while second movable valve
member 181 is in contact with fourth valve seat 183 (second
position, FIG. 2B).
[0113] In some embodiments valve members 171 and 181 are configured
for positioning in at least one intermediate position, between the
first positions and the second positions, allowing fluid from a
given inlet port to flow to two outlet ports. Specifically, a
portion of the fluid entering valve 100 from ambient inlet port 151
is directed to compressor-inlet outlet port 161, and another
portion is directed to heat-exchanger cold-stream inlet outlet port
162. Similarly, a portion of the fluid entering through
compressor-outlet inlet port 152 is directed to heat-exchanger
cold-stream inlet outlet port 162 and another portion is directed
to exhaust outlet port 163. The utility of some such intermediate
positions is described hereinbelow.
Gas-Turbine with 5-Port Valve 100
[0114] FIG. 3 schematically depict an exemplary embodiment of a
gas-turbine 10, comprising a valve 100 (as described above)
operable in a Brayton cycle (FIG. 3A) and in an inverse Brayton
cycle (FIG. 3B). Gas-turbine 10 further includes compressor 20 and
turbine 22, together mounted on a common rotatable shaft 24
constituting a spool, combustor 26 and heat-exchanger 52.
Gas-turbine 10 also includes a 3-way valve 220 having an inlet 224
and two outlets, 221 and 222. Valve 220 may be positioned as
depicted in FIG. 3A to providing fluid communication between inlet
224 and outlet 221, or as depicted in FIG. 3B providing fluid
communication between inlet 224 and outlet 222.
[0115] Valve 100 is configured to switch gas-turbine 10 between a
high-pressure operation mode (Brayton cycle) depicted in FIG. 3A,
and a low-pressure operation mode (inverse Brayton cycle) depicted
in FIG. 3B.
[0116] In FIG. 3A (configuration "1") both valve members 171 and
181 of valve 100 are in a first position (as in FIG. 2A) directing
fluid entering through ambient inlet port 151 to compressor-inlet
outlet port 161, and fluid entering through compressor-outlet inlet
port 152 to heat-exchanger cold-stream inlet outlet port 162.
Ambient air is drawn through ambient inlet port 151 past
compressor-inlet outlet port 161 into compressor 20, pass through
compressor-outlet inlet port 152 and heat-exchanger cold-stream
inlet outlet port 162 of valve 100 into cold-stream conduit 54 of
heat-exchanger 52, to combust in combustor 26. The combusted gases
expand through turbine 22, and exit turbine 22 into hot-stream
conduit 56 of heat-exchanger 52. 3-way valve 220 is set so that the
combusted gases exit gas-turbine 10 through exhaust outlet 30 after
exiting heat-exchanger 52.
[0117] In FIG. 3B (configuration "2") both valve members 171 and
181 of valve 100 are in a second position (as in FIG. 2B) directing
fluid incoming through ambient inlet port 151 to heat-exchanger
cold-stream inlet outlet port 162, and fluid coming through
compressor-outlet inlet port 152 to exhaust outlet port 163.
Ambient air is drawn through ambient inlet port 151 past
heat-exchanger cold-stream inlet outlet port 162 into cold-stream
conduit 54 of heat-exchanger 52 and combusts in combustor 26. The
combusted gases exit turbine 22 into hot-stream conduit 56 of
heat-exchanger 52. 3-way valve 220 is set to directing the
combusted gases into compressor 20. The combusted gases exit
compressor 20 and pass through compressor-outlet inlet port 152 to
exit gas-turbine 10 through exhaust outlet port 163 of valve
100.
[0118] It is important to note that generally the flow directions
through the various conduits including fluid conduits 120 of valve
100 are the same in both high-pressure operation mode and
low-pressure operation mode, and do not change when switching
gas-turbine 10 from one mode to the other.
[0119] In FIG. 4, the relation of thermal efficiency as a function
of power output for gas-turbine 10 configured with valve 100 as
described above is illustrated. Curve 410 is the thermal efficiency
of gas-turbine 10 operating in the low-pressure operation mode
(FIG. 3B) and curve 412 is the thermal efficiency of gas-turbine 10
operating in the high-pressure operation mode (FIG. 3A).
Further Embodiments of Gas-Turbine with 5-Port Valve 100
[0120] In some embodiments, a gas-turbine comprises an embodiment
of a valve similar to valve 100 of FIGS. 2A and 2B, where the valve
is integrated in the gas-turbine in "reverse". In such an
embodiment, valve 100 includes three inlet ports and two outlet
ports: an ambient inlet port 151, a compressor-outlet inlet port
152, a heat-exchanger hot-stream outlet inlet port 153, a
heat-exchanger cold-stream inlet outlet port 162 and an exhaust
outlet port 163. FIG. 5 depict an exemplary embodiment of a
gas-turbine 11, comprising a valve 100, and operable according to a
Brayton cycle (FIG. 5A) and an inverse Brayton cycle (FIG. 5B).
Gas-turbine 11 further includes compressor 20 and turbine 22,
together mounted on common rotatable shaft 24, combustor 26 and
heat-exchanger 52. Gas-turbine 11 also includes a 3-way valve 225
having two inlets, 226 and 227, and an outlet 228. Valve 225 may be
positioned as depicted in FIG. 5A providing fluid communication
between inlet 226 and outlet 228, or as depicted in FIG. 5B
providing fluid communication between inlet 227 and outlet 228.
[0121] Valve 100 is configured to switch gas-turbine 11 between a
high-pressure operation mode in configuration "1" depicted in FIG.
5A, and a low-pressure operation mode in configuration "2" depicted
in FIG. 5B.
[0122] In configuration "1" (FIG. 5A) both valve members 171 and
181 of valve 100 are in a first position directing fluid from
compressor-outlet inlet port 152 to heat-exchanger cold-stream
inlet outlet port 162 and from heat-exchanger hot-stream outlet
inlet port 153 to exhaust outlet port 163. Ambient air is drawn
through inlet 28 of gas-turbine 11 and through inlet 226 and outlet
228 of valve 225 into compressor 20, pass through compressor-outlet
inlet port 152 to heat-exchanger cold-stream inlet outlet port 162
of valve 100 into cold-stream conduit 54 of heat-exchanger 52, and
combusts in combustor 26. The combusted gases expand through
turbine 22 and pass through hot-stream conduit 56 of heat-exchanger
52. From heat-exchanger 52 the combusted gases pass through
heat-exchanger hot-stream outlet inlet port 153 of valve 100, and
are discharged through exhaust outlet port 163 to the
surroundings.
[0123] In configuration "2" (FIG. 5B) both valve members 171 and
181 of valve 100 are in a respective second position. Ambient air
is drawn through ambient inlet port 151 and heat-exchanger
cold-stream inlet outlet port 162 of valve 100 into cold-stream
conduit 54 of heat-exchanger 52, and combusts in combustor 26. The
combusted gases expand through turbine 22, exiting into hot-stream
conduit 56 of heat-exchanger 52. The combusted gases from
heat-exchanger 52 pass through 3-way valve 225 to compressor 20,
pass through compressor-outlet inlet port 152 and through exhaust
outlet port 163 to exit gas-turbine 11.
Embodiment of 6-Port Valve Suitable for Use with Gas-Turbine
[0124] In some embodiments described above, exhaust exits
gas-turbine 10 through two different outlets. In some embodiments
described below the exhaust exits a gas-turbine through a single
exhaust outlet.
[0125] FIGS. 6A and 6B depict a valve 102, suitable for use with a
gas-turbine, in side cross-section. Valve 102 comprises a valve
body 110 defining a single void in the form of a plurality of fluid
conduits 120. Valve 102 further includes an ambient inlet port 151,
a compressor-outlet inlet port 152, a heat-exchanger hot-stream
outlet inlet port 153, a compressor-inlet outlet port 161, a
heat-exchanger cold-stream inlet outlet port 162 and an exhaust
outlet port 163, the six ports being in fluid communication one
with the other through fluid conduits 120.
[0126] Valve 102 further includes a first valve member 171 and a
second valve member 181. First valve member 171 is movable inside
valve body 110 having at least two positions: a first position,
depicted in FIG. 6A, in contact with a first valve seat 172 in
valve body 110 blocking fluid communication between ambient inlet
port 151 and heat-exchanger cold-stream inlet outlet port 162; and
a second position, depicted in FIG. 6B, in contact with a second
valve seat 173 in valve body 110 blocking fluid communication
between ambient inlet port 151 and compressor-inlet outlet port
161. Second movable valve member 181 is movable inside valve body
110 having at least two positions: a first position, depicted in
FIG. 6A, in contact with a third valve seat 182 in valve body 110
blocking fluid communication between compressor-outlet inlet port
152 and exhaust outlet port 163; and a second position, depicted in
FIG. 6B, in contact with a fourth valve seat 183 in valve body 110
blocking fluid communication between compressor-outlet inlet port
152 and heat-exchanger cold-stream inlet outlet port 162.
[0127] Valve 102 also includes a check valve 130 operable as a
unidirectional valve and configured in valve body 110 to allow
fluid flowing from heat-exchanger hot-stream outlet inlet port 153
to any of the outlet ports 161, 162 or 163 of valve 102, and to
block fluid flowing from any of the outlet ports of valve 102 out
through heat-exchanger hot-stream outlet inlet port 153.
[0128] As discussed with reference to valve 100, in some
embodiments, valve members 171 and 181 of valve 102 are configured
for cooperative movement, that is to say both valve members move
together between the first position (FIG. 6A) and the second
position (FIG. 6B). In some embodiments, valve members 171 and 181
are independently operable. For example, in such embodiments valve
member 171 is in contact with first valve seat 172 (first position,
FIG. 6A), while second movable valve member 181 is in contact with
fourth valve seat 183 (second position, FIG. 6B).
[0129] As discussed with reference to valve 100, in some
embodiments valve members 171 and 181 of valve 102 are configured
for positioning in at least one intermediate position, between the
first positions and the second positions, thereby allowing fluid
from a given inlet port to flow to two outlet ports. The utility of
some such intermediate positions is described hereinbelow.
Gas-Turbine Comprising 6-Port Valve 102
[0130] FIG. 7 depict an exemplary embodiment of a gas-turbine 12
comprising an embodiment of valve 102, and operable in a Brayton
cycle (FIG. 7A) and in an inverse Brayton cycle (FIG. 7B).
Gas-turbine 12 also includes 3-way valve 220. An outlet 221 of
valve 220 is connected to heat-exchanger hot-stream outlet inlet
port 153 of valve 102 so that exhaust gas is discharged through
exhaust outlet port 163 of valve 102.
[0131] Valve 102 is configured to switch gas-turbine 12 between a
high-pressure operation mode depicted in FIG. 7A, and a
low-pressure operation mode depicted in FIG. 7B
[0132] In FIG. 7A both valve members 171 and 181 of valve 102 are
in a respective first position. Ambient air is drawn through
ambient inlet port 151 and compressor-inlet outlet port 161 of
valve 102 into compressor 20, pass through compressor-outlet inlet
port 152 and heat-exchanger cold-stream inlet outlet port 162 of
valve 102 into cold-stream conduit 54 of heat-exchanger 52 to
combust in combustor 26. The combusted gases expand through turbine
22, and exit turbine 22 into hot-stream conduit 56 of
heat-exchanger 52. The combusted gases are directed by 3-way valve
220 to heat-exchanger hot-stream outlet inlet port 153 of valve
102. In valve 102, the combusted gases pass through check valve 130
and are then discharged to the surroundings through exhaust outlet
port 163.
[0133] In FIG. 7B both valve members 171 and 181 of valve 102 are
in a respective second position. Ambient air is drawn through
ambient inlet port 151 and through heat-exchanger cold-stream inlet
outlet port 162 of valve 102 into cold-stream conduit 54 of
heat-exchanger 52 to combust in combustor 26. The combusted gases
expand through turbine 22 into hot-stream conduit 56 of
heat-exchanger 52. 3-way valve 220 directs the gases into
compressor 20, to exit compressor 20, and pass through
compressor-outlet inlet port 152 of valve 102 and exit gas-turbine
12 through exhaust outlet port 163 of valve 102. Check valve 130
blocks the exhaust gases from flowing back through heat-exchanger
hot-stream outlet inlet port 153 of valve 102 towards 3-way valve
220.
Additional Embodiment of 6-Port Valve Suitable for Use with
Gas-Turbine
[0134] FIGS. 8A and 8B depict a valve 103, suitable for use with a
gas-turbine, in side cross-section. Valve 103 comprises a valve
body 110 defining a single void in the form of a plurality of fluid
conduits 120. Valve 103 further includes an ambient inlet port 151,
a compressor-outlet inlet port 152, a heat-exchanger hot-stream
outlet inlet port 153, a compressor-inlet outlet port 161, a
heat-exchanger cold-stream inlet outlet port 162 and an exhaust
outlet port 163, the six ports being in fluid communication one
with the other through fluid conduits 120. Valve 103 further
comprises a bypass conduit providing fluid communication between
heat-exchanger hot-stream outlet inlet port and compressor-inlet
outlet port.
[0135] Valve 103 further includes three valve members, 171, 181 and
191.
[0136] First valve member 171 is movable inside valve body 110
having at least two positions: a first position as depicted in FIG.
8A in contact with a first valve seat 172 in valve body 110, and a
second position, depicted in FIG. 8B, in contact with a second
valve seat 173 in valve body 110. In the first position first valve
member 171 in said first position blocks fluid communication
between ambient inlet port 151 and heat-exchanger cold-stream inlet
outlet port 162 and in the second position (FIG. 8B) blocks fluid
communication between ambient inlet port 151 and compressor inlet
outlet port 161.
[0137] Second valve member 181 is movable inside valve body 110
having at least two positions: a first position, depicted in FIG.
8A, in contact with a third valve seat 182 in valve body 110, and a
second position, depicted in FIG. 8B, in contact with a fourth
valve seat 183 in valve body 110. In the first position (FIG. 8A),
second valve member 181 blocks fluid communication between
heat-exchanger hot-stream outlet inlet port 153, and heat-exchanger
cold-stream inlet outlet port 162 and in the second position (FIG.
8B) blocks fluid communication between compressor-outlet inlet port
152 and heat-exchanger cold-stream inlet outlet port 162.
[0138] Third valve member 191 is movable inside valve body 110
having at least two positions: a first position, depicted in FIG.
8A, in contact with a fifth valve seat 192 in valve body 110, and a
second position, depicted in FIG. 8B, in contact with a sixth valve
seat 193 in valve body 110. In the first position (FIG. 8A) third
valve member 191 blocks fluid communication between heat-exchanger
hot-stream outlet inlet port 153 and compressor inlet outlet port
161 through the bypass conduit and in the second position (FIG. 8B)
third valve member 191 blocks fluid communication between
heat-exchanger hot-stream outlet inlet port 153 and exhaust outlet
port 163.
[0139] Analogously to the discussed above with reference to valves
100 and 102, in some embodiments, two or three valve members 171,
181 and 191 are configured for cooperative movement. Analogously to
the discussed above with reference to valves 100 and 102, in some
embodiments, one or more valve members 171, 181 and 191 are
independently operable.
Gas-Turbine Comprising 6-Port Valve 103
[0140] FIG. 9 depict an exemplary embodiment of a gas-turbine 13
comprising an embodiment of a valve 103, operable according to a
Brayton cycle (FIG. 9A) and according to an inverse Brayton cycle
(FIG. 9B)
[0141] Valve 103 is configured to switch gas-turbine 13 between a
high-pressure operation mode depicted in FIG. 9A, and a
low-pressure operation mode depicted in FIG. 9B.
[0142] In FIG. 9A, valve members 171, 181 and 191 of valve 103 are
in a respective first position. Ambient air is drawn through
ambient inlet port 151 and compressor-inlet outlet port 161 of
valve 103 into compressor 20, and pass through compressor-outlet
inlet port 152 and heat-exchanger cold-stream inlet outlet port 162
of valve 103 into cold-stream conduit 54 of heat-exchanger 52 to
combust in combustor 26. The combusted gases expand through turbine
22 and exit through hot-stream conduit 56 of heat-exchanger 52 and
through heat-exchanger hot-stream outlet inlet port 153, to be
discharged through exhaust outlet port 163 to the surroundings.
[0143] In FIG. 9B all three valve members 171, 181 and 191 of valve
103 are in a respective second position. Ambient air is drawn
through ambient inlet port 151 and heat-exchanger cold-stream inlet
outlet port 162 of valve 103 into cold-stream conduit 54 of
heat-exchanger 52 to combust in combustor 26. The combusted gases
enter turbine 22 and exit turbine 22 into hot-stream conduit 56 of
heat-exchanger 52. Exiting hot-stream conduit 56, the combusted
gases are drawn through heat-exchanger hot-stream outlet inlet port
153, through the bypass conduit to compressor-inlet outlet port 161
of valve 103 into compressor 20. From compressor 20, the combusted
gases pass through compressor-outlet inlet port 152 of valve 103 to
be discharged from gas-turbine 13 through exhaust outlet port 163
of valve 103.
[0144] In general terms, in some embodiments a gas-turbine such as
13 is switched between a high-pressure operation mode and a
low-pressure operation mode as is described above, using a six-port
valve, having three inlet ports designated "X" (ambient inlet port
151), "Y" (compressor-outlet inlet port 152) and "Z"
(heat-exchanger hot-stream outlet inlet port 153), and three outlet
ports designated "x" (compressor-inlet outlet port 161), "y"
(heat-exchanger cold-stream inlet outlet port 162) and "z" (exhaust
outlet port 163). In a first configuration, the valve provides
fluid communication exclusively between inlet port "X" and outlet
port "x", between inlet port "Y" and outlet port "y" and between
inlet port "Z" and outlet port "z". In a second configuration, the
valve provides fluid communication exclusively between inlet port
"X" and outlet port "y", between inlet port "Y" and outlet port "z"
and between inlet port "Z" and outlet port "x". Providing flow
communication exclusively between the specified pairs of inlet and
outlet ports means that only fluid communication which is
explicitly described between the specified ports is provided, and
there is no fluid communication between the ports which is not
explicitly described.
Multi-Power Single-Spool Gas-Turbine
[0145] Aspects of the invention relate to multiport valves suitable
for use with gas-turbines that allow switching between
high-pressure, low-pressure and at least one intermediate-pressure
operation modes of a gas-turbine. According to such embodiments, a
valve is configured and operable to be in at least one intermediate
configuration, in addition to the high-pressure (Brayton cycle)
configuration "1" and low-pressure (inverse Brayton cycle)
configuration "2" discussed above, for example in FIGS. 8A and 8B.
Such an intermediate configuration allows a gas-turbine to work in
a pressure mode intermediate between the high and low-pressure
operation modes.
[0146] FIG. 10 depicts an embodiment of a valve 103 in an exemplary
intermediate configuration, valve members 171, 181 and 191 being in
an intermediate position, between the respective first position and
second position. In such an intermediate configuration, fluid from
a given inlet port is directed to flow to two outlet ports.
Specifically, a portion of the fluid entering valve 103 from
ambient inlet port 151 is directed to compressor-inlet outlet port
161, and another portion to heat-exchanger cold-stream inlet outlet
port 162. Similarly, a portion of the fluid entering through
compressor-outlet inlet port 152 is directed to heat-exchanger
cold-stream inlet outlet port 162 and another portion is directed
to exhaust outlet port 163. A portion of the fluid entering valve
103 from heat-exchanger hot-stream outlet inlet port 153 is
directed to exhaust outlet port 163 and another portion is directed
to compressor-inlet outlet port 161.
[0147] In some embodiments, a mixing region 126 within fluid
conduits 120 is configured to function as jet pump ejector. In some
embodiments, such configuration includes fashioning at least one of
valve members 171, 181 as an airfoil having a pre-defined
aerodynamic profile. When mixing region 126 is configured as a jet
pump ejector, the pressure of fluid flowing from compressor-outlet
inlet port 152 to heat-exchanger cold-stream inlet outlet port 162
drops, producing a suction zone (for example, through the Bernoulli
effect). The suction zone sucks fluid from ambient inlet port 151
into valve 103 and to heat-exchanger cold-stream inlet outlet port
162.
[0148] FIG. 11 depicts an exemplary embodiment of a gas-turbine 13,
configured with a valve 103 and operable in an intermediate
pressure operation mode in addition to a high-pressure operation
mode (configuration "1", FIG. 8A) and a low-pressure operation mode
(configuration "2", FIG. 8B). During operation in the intermediate
pressure operation mode when valve members 171, 181 and 191 are
positioned as depicted in FIG. 10, compressor 20 generates a
low-pressure region around compressor-inlet outlet port 161 of
valve 103, so a portion of ambient air is drawn from ambient inlet
port 151 into compressor-inlet outlet port 161. Additionally, a
portion of the gas coming from heat-exchanger 52 into
heat-exchanger hot-stream outlet inlet port 153 is drawn into
compressor 20 through compressor-inlet outlet port 161.
[0149] Compressed fluid coming from compressor 20 flows into
compressor-outlet inlet port 152 at high-pressure and is directed
to both heat-exchanger cold-stream inlet outlet port 162 and to
exhaust outlet port 163, the exact ratio dependent, inter alia, on
the position of valve member 181.
[0150] Thus, in some embodiments when one or more of valve members
171, 181 and 191 are positioned in an intermediate position, for
example as depicted in FIG. 11, a gas-turbine 13 is operable in a
mode where the pressure is between the highest and lowest pressures
and consequently the power output is between the highest and lowest
power outputs. In such embodiments, in all three modes the thermal
efficiency of the gas-turbine is relatively high (see curve 414 in
FIG. 4).
[0151] In some embodiments an intermediate pressure operation mode
of a gas-turbine such as 13 is obtained by positioning only one
valve member 171, 181 or 191 in a respective intermediate position
while the other two valve members are positioned in either a first
or second position. In some embodiments, an intermediate pressure
operation mode of gas-turbine 13 is obtained by positioning two
valve members in a respective intermediate position, while the
remaining valve member is positioned in either a first or a second
position.
[0152] In some embodiments, a gas-turbine such as gas-turbine 13
comprising a valve with three valve members as described herein
such as valve 103, is switched to an intermediate pressure
operation mode by positioning a first valve member 171 and a second
valve member 181 in an intermediate position, substantially as is
described above, and positioning a third valve member 191 in a
first position or in a second position.
[0153] Analogously, in some embodiments, a gas-turbine such as
gas-turbine 10 of FIG. 3 or gas-turbine 11 of FIG. 5, comprising a
valve with two valve members as described herein, such as valve
100, is switched to an intermediate pressure operation mode by
positioning a first valve member 171 and a second valve member 181
of the valve in an intermediate position. Similarly, in some
embodiments a gas-turbine such as gas-turbine 12 of FIG. 7 is
switched to an intermediate pressure operation mode by positioning
a first valve member 171 and a second valve member 181 of a valve
such as valve 102 in an intermediate position. In some such
embodiments, a mixing region analogue to mixing region 126 of valve
103 is formed in the respective two-valve member valve (e.g., 100
or 102) to function as jet pump ejector. In some embodiments of
gas-turbines such as 10, 11 and 12, a continuity of intermediate
pressure operation modes is obtained by positioning valve members
171 and 181 of respective valves such as 100 and 102 in a
continuity of positions.
[0154] In some embodiments, the position of at least one valve
member is not continuously variable. That is to say, one or a
series of intermediate pressure operation modes of gas-turbine 13
is obtained by maintaining at least one valve member in a fixed
position while varying the position of the remaining valve members.
In some embodiments, valve members 171, 181 and 191 are moveable
between two endpoints, and may be maintained at a specific
intermediate position between the endpoints. In such embodiments,
valve 103 has at least three configurations, and gas-turbine 13
comprising valve 103 may be efficiently operated in at least three
different pressure operation modes.
[0155] Returning to FIG. 4, the relation of thermal efficiency as a
function of power output for gas-turbine 13 including valve 103 as
described above is schematically depicted, where curve 410
corresponds to a single spool gas-turbine operating in the
low-pressure operation mode (as is described in FIG. 9B), curve 412
corresponds to gas-turbine 13 operating in a high-pressure
operation mode (as is described in FIG. 9A), and curve 414
corresponds to gas-turbine 13 operating in one exemplary
intermediate pressure operation mode as described above in FIG. 11,
where mixing region 126 is configured as a jet pump ejector.
Valves for Substantially Continuous Efficient Power Output
[0156] In some embodiments, a valving system is provided that
allows high-pressure operation mode and/or low-pressure operation
mode of a gas-turbine (including, inter alia, a combustor and a
heat-exchanger) at a continuously varying power output at relative
high efficiency. Such a valving system operates by reducing the
mass flow of fluid to the combustor through the heat-exchanger.
Such mass flow reduction is similar to the achieved by inlet
throttling, for example with the use of variable inlet guide
vanes.
[0157] In the art, variable inlet guide vanes are often used with
large gas-turbines. Such guide vanes are unsuitable for use with
small turbines due to high expense and technical complexity at
small sized. Further, as there is a need for matching between the
whirl caused by the guide vanes and the compressor blades, the
guide vanes can be varied only by about 15% which allows a change
of about 20% in power output at reasonable efficiencies.
[0158] FIG. 13 show an embodiment of a valve 104, suitable for use
with a gas-turbine, schematically depicted in side cross-section.
In valve 104, valve member 181 is configured to have a continuity
of positions when in the first position in contact with valve seat
182, allowing a gas-turbine including valve 104 and operating in a
high-pressure operation mode to operate in a continuity of output
power levels. Specifically, valve member 181 is relatively thick
and valve seat 182 appropriately configured so that valve member
181 has a range of motion defining a continuity of positions in
continuous contact with valve seat 182 thereby blocking fluid
communication through valve seat 182. Through the continuity of
positions in the first position, the varying bulk of valve member
181 located in the fluid path between compressor-outlet inlet port
152 and heat-exchanger cold-stream inlet outlet port 162, allows
the size of the fluid path to be controllably varied.
[0159] FIGS. 13A and 13B show two exemplary such positions where
valve member 181 is in the first position 1 in contact with valve
seat 182, but the exact position of valve member 181 varies the
size of a fluid path 127 inside valve 104, between
compressor-outlet inlet port 152 and heat-exchanger cold-stream
inlet outlet port 162, thereby varying the gas-turbine output power
level. For example, when valve member 181 is in position as
depicted in FIG. 13A, fluid path 127 is wide, allowing for a high
flow rate of fluid from compressor-outlet inlet port 152 to
heat-exchanger cold-stream inlet outlet port 162 so that the
gas-turbine generates a relatively high output power level; and
when valve member 181 is in a position as depicted in FIG. 13B,
fluid path 127 is narrow, allowing for a low flow-rate of fluid, so
that the gas-turbine generates a relatively low output power
level.
[0160] It is understood that valve 104 allows a gas-turbine to
operate in a high-pressure operation mode in a continuity of
configurations as described above, since valve member 181 is
continuously in contact with valve seat 182, in the described
continuity of positions, substantially blocking flow of fluid from
compressor-outlet inlet port 152 to exhaust outlet port 163.
Further, when valve 104 is in a high-pressure mode configuration as
described above, valve member 171 is maintained in contact with
valve seat 172, substantially blocking flow from ambient inlet port
151 to heat-exchanger cold-stream inlet outlet port 162.
[0161] Analogously to valve 100 as depicted in FIG. 2B, valve 104
further allows an associated gas-turbine to operate in a
low-pressure operation mode when valve members 171 and 181 are in a
second position (not shown). Specifically, valve 104 is in a
low-pressure mode configuration when valve members 171 and 181 are
in contact with valve seats 173 and 183, respectively. Thus,
analogously to valve 100 in gas-turbine 10 of FIG. 3, valve 104 is
operable to switch a gas-turbine between a high-pressure operation
mode according to a Brayton cycle and a low-pressure operation mode
according to an inverse Brayton cycle, and in addition to varying
the gas-turbine output power level in the high-pressure operation
mode. Similarly, in a gas-turbine such as gas-turbine 11 depicted
in FIG. 5, multiport valve 104 is operable to switch the
gas-turbine between a high-pressure operation mode according to a
Brayton cycle and a low-pressure operation mode according to an
inverse Brayton cycle, and in addition to varying the gas-turbine
output power level in the high-pressure operation mode.
[0162] FIGS. 14A and 14B depict an embodiment of a valve 105,
suitable for use with a gas-turbine, schematically depicted in side
cross-section. In valve 105, valve member 171 is configured to have
a continuity of positions when in the second position in contact
with valve seat 173, allowing a gas-turbine including valve 105 and
operating in a low-pressure operation mode, to operate in a
continuity of output power levels. Analogously to the described
with reference to FIG. 13, in FIG. 14 valve member 171 is
relatively thick and valve seat 173 is appropriately configured so
that valve member 171 has a range of motion defining a continuity
of positions in continuous contact with valve seat 173 thereby
blocking fluid communication through valve seat 173. Through the
continuity of positions in the second position, the varying bulk of
valve member 171 located in the fluid path between ambient inlet
port 151 and heat-exchanger cold-stream inlet outlet port 162,
allows the size of the fluid path to be controllably varied.
[0163] FIGS. 14A and 14B depict two exemplary such positions where
valve member 171 is in the second position in contact with valve
seat 173, but the exact position of valve member 171 effects the
gas-turbine output power level by varying the size of path 128
inside valve 105, between ambient inlet port 151 and heat-exchanger
cold-stream inlet outlet port 162. For example, when valve member
171 is in position as depicted in FIG. 14A, fluid path 128 is wide,
allowing for a high flow rate of air from ambient inlet port 151 to
heat-exchanger cold-stream inlet outlet port 162, thereby
generating a high output power level; and when valve member 171 is
in position as depicted in FIG. 14B, fluid path 128 is narrow
allowing for a low flow rate of fluid so that the gas-turbine
generates a low output power level.
[0164] It is understood that valve 105 allows a gas-turbine to
operate in a low-pressure operation mode in a continuity of
configurations as described above, since valve member 171 is
continuously in contact with valve seat 173 in the described
continuity of positions, substantially blocking flow of fluid from
ambient inlet port 151 to compressor-inlet outlet port 161.
Further, when valve 105 is in such a low-pressure mode
configuration as described above, valve member 181 is maintained in
contact with valve seat 183, substantially blocking flow from
compressor-outlet inlet port 152 to heat-exchanger cold-stream
inlet outlet port 162.
[0165] Analogously to valve 100 as depicted in FIG. 2A, valve 105
further allows an associated gas-turbine to operate in a
high-pressure operation mode when valve members 171 and 181 are in
a first position (not shown). Specifically, valve 105 is in a
high-pressure mode configuration when valve members 171 and 181 are
in contact with valve seats 172 and 182, respectively. Thus,
analogously to valve 100 in gas-turbine 10 of FIG. 3, valve 105 is
operable to switch a gas-turbine between a high-pressure operation
mode according to a Brayton cycle and a low-pressure operation mode
according to an inverse Brayton cycle, and in addition to varying
the gas-turbine output power level in the low-pressure operation
mode.
[0166] In some embodiments, a valve includes two separate valve
members that allow both switching of an associated gas-turbine
between a high-pressure and a low-pressure operation mode, and
varying continuously the size of the path to the heat-exchanger.
Referring to FIGS. 15A, 15B, and 15C, valves 106, 107 and 108,
respectively, are schematically depicted. Valves 106, 107 and 108
are suitable for use with a gas-turbine and configured for
switching a gas-turbine comprising valves 106, 107 or 108 between a
high-pressure and a low-pressure operation modes. Valves 106, 107
and 108 are also configured for continuously varying output power
level of an associated gas-turbine by allowing a continuous varying
of the size of the fluid path to the heat-exchanger.
[0167] In valve 106 depicted in FIG. 15A, a movable valve member
281 is rotatably moveable around valve member axis 184, sharing an
axis of rotation with valve member 181. While valve member 171
maintains contact with valve seat 172 and valve member 181
maintains contact with valve seat 182 (so that valve 106 is in a
high-pressure mode configuration) valve member 281 is moveable
through a continuity of positions allowing variation of the size of
fluid path 127, thereby varying the output power level of the
associated gas-turbine. Thus, analogously to valve 100 in
gas-turbine 10 of FIG. 3, valve 106 is operable to switch a
gas-turbine between a high-pressure operation mode according to a
Brayton cycle and a low-pressure operation mode according to an
inverse Brayton cycle, and in addition to varying the gas-turbine
output power level in the high-pressure operation mode.
[0168] A similar variation in the size of the fluid path is
implementable in a multiport valve analogous to the depicted in
FIG. 5.
[0169] In valve 107 depicted in FIG. 15B, a valve member 271 is
movable around valve member axis 174 thereby operable to vary the
size of fluid path 128 from ambient inlet port 151 to the
heat-exchanger (not shown) through heat-exchanger cold-stream inlet
outlet port 162, while valve members 171 and 181 maintain contact
with valve seats 173 and 183 respectively, so that valve 107 is in
a low-pressure configuration. Thus, analogously to valve 100 in
gas-turbine 10 of FIG. 3, valve 107 is operable to switch a
gas-turbine between a high-pressure operation mode according to a
Brayton cycle and a low-pressure operation mode according to an
inverse Brayton cycle, and in addition to varying the gas-turbine
output power level in the low-pressure operation mode.
[0170] In valve 108 depicted in FIG. 15C, two valve members, 171
and 271, both movable around first valve member axis 174, and two
valve members 181 and 281, both movable around second valve member
axis 184, allow the size of fluid paths 127 and 128, respectively,
to be continuously varied while valve 108 is set in high-pressure
configuration and in low-pressure configuration. Analogously to
valve 100 of FIG. 3, valve 108 is operable to switch a gas-turbine
between a high-pressure operation mode according to a Brayton cycle
and a low-pressure operation mode according to an inverse Brayton
cycle, and in addition to varying the gas-turbine output power
level in the low-pressure operation mode and in the high-pressure
operation mode. A similar variation in the size of the fluid path
is implementable in a multiport valve analogous to the depicted in
FIG. 5.
[0171] Returning to FIG. 4, the relationship of thermal efficiency
to power output for a gas-turbine including a valve as described in
FIGS. 13A, 13B, 14A, 14B, 15A 15B and 15C is schematically
depicted. Curve 412 corresponds to a gas-turbine operating in the
high-pressure operation mode, for example with a valve 100 of FIG.
2A, while curve 416 corresponds to a gas-turbine operating in
high-pressure operation mode with a valve of FIGS. 12A, 12B 14A or
14C. Curve 410 corresponds to a gas-turbine operating in the
low-pressure operation mode, for example with a valve 100 of FIG.
2B, while curve 418 corresponds to the gas-turbine operating in
low-pressure operation mode with a valve of FIGS. 14A, 14B 15B or
15C.
[0172] In the embodiments described above, the valve members are
substantially plates configured to rotatably move between the
different positions around a single axis close to or at an edge of
the valve member. Generally, the teachings herein may be
implemented using any suitable type of valve member. For example,
in some embodiments valve members used include suitably-configured
butterfly valves (especially tricentric butterfly valves), ball
valves or rotary valves.
[0173] Gas-turbines using valves as described herein may be of any
desired power capacity. That said, in some embodiments, a
gas-turbine is configured for producing up to about 100 kW. In some
embodiments, a gas-turbine is configured for producing from about
14 kW to about 40 kW of power. In some embodiments, a gas-turbine
is configured for producing from about 7 kW to about 36 kW of
power. Such low powers are useful, for example, for powering a
small motor vehicle, such as a light truck or an automobile.
Reduced NOx Emission Inverse-Brayton Cycle Gas-Turbine
[0174] Aspects of the invention relate to gas-turbines operating in
a low-pressure operation mode according to an inverse Brayton cycle
that have reduced NOx emissions. Due to poor mixing and
vaporization at low power operation which create local high
temperature zones, gas-turbine NOx emissions are higher under
partial load. In some embodiments of the invention, inlet air is
mixed with a portion of exhaust and is directed into the combustor,
thereby decreasing the oxygen content of the combustible mixture in
the combustor, and as a result, reducing the amount of NOx
emissions.
[0175] Thus, according to an aspect of some embodiments of the
invention, there is provided a method of operating a gas-turbine
according to an inverse Brayton cycle, comprising: a) providing a
conduit allowing fluid communication between a compressor of the
gas-turbine and a cold-stream inlet of a heat-exchanger of the
gas-turbine; and b) during inverse Brayton cycle operation of the
gas-turbine, directing fluid from the compressor to the
heat-exchanger cold-stream inlet through the conduit so that a
portion of the fluid entering the heat-exchanger cold-stream inlet
is from the compressor. In some embodiments, between about 30% and
about 70% (in some embodiments, between about 40% and about 60%, in
some embodiments between about 45% and about 55%) by mass of the
fluid entering the heat-exchanger cold-stream inlet is from the
compressor. In one specific preferred embodiment, approximately 50%
by mass of the fluid entering the heat-exchanger cold-stream inlet
is from the compressor.
[0176] In some embodiments, the method further comprises: adjusting
a size of the conduit so as to control an amount of fluid entering
the cold-stream inlet from the compressor.
[0177] According to an aspect of some embodiments of the invention
there is also provided a gas-turbine comprising, when operating
according to an inverse Brayton cycle, a) an air inlet configured
to direct fluid into a cold-stream conduit of a heat-exchanger
through a cold-stream inlet; b) conduits to direct fluid from the
cold-stream conduit to a combustor, from the combustor to a
turbine, from the turbine to a hot-stream conduit of the
heat-exchanger, from the hot-stream conduit to a compressor, and
from the compressor to an exhaust outlet; and c) a conduit allowing
passage of fluid from the compressor into the cold-stream inlet of
the heat-exchanger.
[0178] In some embodiments, the gas-turbine is configured to
operate only according to an inverse Brayton cycle.
[0179] In some embodiments the gas-turbine is configured to
optionally operate according to a Brayton cycle, for example as
described herein. In some such embodiments, the gas-turbine is
configured so that during operation according to a Brayton cycle,
the conduit is substantially blocked preventing passage of fluid
between the compressor and the cold-stream inlet.
[0180] In some embodiments, the conduit allowing passage of fluid
from the compressor into the cold-stream inlet is of fixed
size.
[0181] In some embodiments, the size of the conduit allowing
passage of fluid from the compressor into the cold-stream inlet is
adjustable, for example allowing varying an amount of fluid passing
from the compressor into the cold-stream inlet.
[0182] In some embodiments, the conduit allowing passage of fluid
from the compressor into the cold-stream inlet is configured so
that during operation according to an inverse Brayton cycle between
about 30% and about 70% (in some embodiments, between about 40% and
about 60%, in some embodiments 45% and about 55%) by mass of the
fluid entering the heat-exchanger cold-stream inlet is from the
compressor.
[0183] In some embodiments, the conduit allowing passage of fluid
from the compressor into the cold-stream inlet of the
heat-exchanger is passive, that is to say, occurs due to the
pressure differential between the two regions without investment of
any additional work. In some embodiments, the conduit is active,
that is to say, comprises a component such as a pump that performs
work to direct fluid from the compressor to the cold-stream inlet
of the heat-exchanger.
[0184] FIG. 16 depicts an exemplary embodiment of a gas-turbine 19
including a valve 109 suitable for use with a gas-turbine and
useful for reducing the amount of NOx emissions of the gas-turbine
in low-pressure operation mode. In the embodiment depicted in FIG.
16, valve 109 comprises five ports and two valve members in a
configuration similar to valve 100 depicted in FIG. 2. In the
embodiment depicted in FIG. 16, valve 109 further comprises a
permeable section 140 of valve body 110 between regions 121 and 122
of fluid conduits 120, allowing passage of fluid from region 121 to
region 122.
[0185] In the embodiment depicted in FIG. 16, region 121 is
up-stream from valve member 181, between valve member 181 and
exhaust outlet port 163 while region 122 is up-stream from valve
member 181, between valve member 181 and heat-exchanger cold-stream
inlet outlet port 162. Permeable section 140 is unidirectional,
only allowing passage of fluid from region 121 to region 122 if the
pressure in region 121 is higher than the pressure in region 122
(e.g., during inverse Brayton cycle operation of gas-turbine 19),
but blocking passage of fluid from region 122 into region 121
(e.g., during Brayton cycle operation of gas-turbine 19).
[0186] Depending on the positions of valve members 171 and 181,
gas-turbine 19 may be set in configurations analagous to the
configurations depicted in for gas-turbine 10 in FIGS. 3A and 3B.
In FIG. 16, gas-turbine 19 is depicted in a configuration analogous
to configuration "2" (FIG. 2B), consequently operating in a
low-pressure operation mode according to an inverse Brayton cycle.
As a result, the pressure in region 121 is higher than the pressure
in region 122 so a portion of the exhaust gas passes from region
121 through permeable section 140 into region 122. The portion of
exhaust gas that passes through permeable section 140 to region 122
mixes with the ambient air coming into gas-turbine 19, reducing
oxygen content in the fluid entering the combustor and consequently
reducing NO'x content in the combusted gas of turbine 19.
[0187] Some such embodiments are superficially similar to reversed
circulation methods implemented in internal combustion engines,
where a significant amount of power is invested in recompressing
exhaust into a high-pressure combustion chamber, reducing thermal
efficiency but reducing NOx emissions. In contrast, in some
embodiments of the invention advantage is taken of the fact that in
a gas-turbine operating according to an inverse Brayton cycle the
pressure in heat-exchanger cold-stream inlet is lower than at the
compressor outlet, so that little if any power is used to bring the
exhaust into the heat-exchanger cold-stream inlet. Additionally, in
some embodiments, the thermal efficiency of the gas-turbine is
increased by the mixing incoming ambient air with the hot
exhaust.
[0188] FIG. 17A depicts an exemplary embodiment of permeable
section 140 in valve 109, including a check valve 141, operable as
a unidirectional valve (e.g., a reed valve) and configured to allow
fluid passage from region 121 to region 122 of fluid conduits 120
of valve 109, and to block passage of fluid in the opposite
direction from region 122 to region 121.
[0189] FIG. 17B depicts another exemplary embodiment of permeable
section 140 of valve 109 integrated in valve member 181.
[0190] Valve member 181 includes a unidirectional valve 186 (e.g.,
a reed valve) allowing fluid passage from region 121 to region 122
and to block fluid passage from region 121 to 122. Specifically,
valve member 181 comprises conduit 185 providing fluid
communication from a face 188 to a face 189 of valve member 181.
Unidirectional valve 186 is disposed inside conduit 185. When the
pressure in region 122 is greater than the pressure in region 121,
valve 186 is closed, sealing conduit 185. When the pressure in
region 121 is greater than the pressure in region 122, valve 186
opens allowing fluid (e.g., exhaust gas from compressor-outlet
inlet port 152) to pass from region 121 to region 122.
[0191] Generally, the size of holes 185 determines the amount of
exhaust gas mixed and therefore the oxygen content of the gas
entering a combustor 26. In some embodiments, the amount of exhaust
gas mixed can be controlled, for example, by changing the number or
size of holes. It is understood that embodiments of permeable
section 140 are not limited to the examples described above and
permeable section 140 can comprise holes, slits, pores and the
like, allowing passage of fluid from region 121 to region 122 of
fluid conduits 120 valve 109.
[0192] The reduction of NOx emissions in a gas-turbine operating in
low-pressure (inverse Brayton mode) is described with reference to
embodiments depicted in FIGS. 16, 17A and 17B where the conduit
directing exhaust from the compressor outlet to mix with air
entering the combustor of a gas-turbine is part of or associated
with a valve as described herein that allows operation of a
gas-turbine in both high and low-pressure modes.
[0193] In some embodiments any of the valves of the invention
described herein, e.g. valve 100, can be utilized to reduce NOx
emission by permitting a portion of the oxygen-depleted exhaust gas
to mix with incoming ambient air in low-pressure operation mode of
a gas-turbine, by positioning valve member 181 close to, but not in
contact with, valve seat 183, when operating the gas-turbine in
low-pressure operation mode. Thus, when valve member 181 allows for
fluid passage between compressor-outlet inlet port 152 and
heat-exchanger cold-stream inlet outlet port 162 in low-pressure
operation mode, exhaust gas is forced into the flow of incoming
ambient air, where the amount of such exhaust passage is controlled
by the exact positioning of valve member 181 with respect to valve
seat 183.
[0194] In some embodiments, a gas-turbine configured for
multipressure operation, e.g., such as described in U.S. Pat. Nos.
6,526,757 and 6,606,864, includes an additional valve (or an
existing valve is modified) that allows passage of exhaust from the
compressor outlet to mix with air entering the combustor during
low-pressure (inverse Brayton) operation, thereby reducing NOx
emissions.
[0195] In some embodiments, a gas-turbine configured for
multipressure operation, e.g., such as described hereinabove,
includes an additional valve (not associated with the valve that
allows switching between high and low-pressure operation) defining
a conduit that allows passage of exhaust from the compressor outlet
to mix with air entering the combustor during low-pressure (inverse
Brayton) operation, thereby reducing NOx emissions. In some
embodiments, such an extra valve has two configurations: closed
(blocking passage of exhaust) and open (allowing passage of
exhaust) defining a fixed conduit size. In some embodiments, the
valve is adjustable, allowing the size of the conduit to be
adjusted to allow varying the amount of exhaust passing to mix with
the air entering the combustor.
[0196] In some embodiments, a gas-turbine configured for
low-pressure (inverse Brayton cycle) operation, e.g. such as known
in the art, includes a valve defining a conduit that allows passage
of exhaust from the compressor outlet to mix with air entering the
combustor, thereby reducing NOx emissions. In some embodiments,
such a valve has two configurations: closed (blocking passage of
exhaust) and open (allowing passage of exhaust). In some
embodiments, the valve is adjustable, allowing variation of the
amount of exhaust passing to mix with the air entering the
combustor.
[0197] In the above, oxygen-depleted exhaust is mixed with ambient
air prior to entering the heat-exchanger of the gas-turbine. In
some embodiments, the exhaust is mixed with the air after exiting
the heat-exchanger cold-stream outlet and prior to entering the
combustor. However, such embodiments are usually considered less
advantageous as lowering combustor inlet temperature reduces
thermal efficiency of the gas-turbine.
[0198] It is appreciated that certain features of the invention,
which are, for clarity, described in the context of separate
embodiments, may also be provided in combination in a single
embodiment. Conversely, various features of the invention, which
are, for brevity, described in the context of a single embodiment,
may also be provided separately or in any suitable subcombination
or as suitable in any other described embodiment of the invention.
Certain features described in the context of various embodiments
are not to be considered essential features of those embodiments,
unless the embodiment is inoperative without those elements.
[0199] Although the invention has been described in conjunction
with specific embodiments thereof, it is evident that many
alternatives, modifications and variations will be apparent to
those skilled in the art. Accordingly, it is intended to embrace
all such alternatives, modifications and variations that fall
within the scope of the appended claims.
[0200] Citation or identification of any reference in this
application shall not be construed as an admission that such
reference is available as prior art to the invention.
[0201] Section headings are used herein to ease understanding of
the specification and should not be construed as necessarily
limiting.
* * * * *