Fuel vaporization power turbine engine, method of assembly and method of use
Some embodiments provide engines comprising: a fuel line; a gas combustion system; a first power turbine positioned within an exhaust gas stream and configured to operate at a first rotation speed; a second power turbine downstream from the first power turbine, and configured to operate at a second rotation speed that is less than the first rotation speed; and a heat exchanger configured to receive the exhaust gas stream, wherein a portion of a fuel line is positioned to receive heat from the heat exchanger configured to heat the fuel; a gear ratio (GR) is defined by a ratio of the second rotation speed to the first rotation speed; a combination of the first power turbine and the second power turbine includes a number of blade rows (NBR); and a system effectiveness control (SEC) is established as a function of the GR and the NBR.
1 . An engine comprising:
a fuel line;
a gas combustion system;
a first power turbine downstream of the gas combustion system and at least partially positioned within an exhaust gas stream downstream of the gas combustion system, and wherein the first power turbine is configured to operate at a first rotation speed;
a second power turbine at least partially positioned within the exhaust gas stream downstream from the first power turbine, wherein the second power turbine is configured to operate at a second rotation speed that is less than the first rotation speed; and
a heat exchanger configured to receive the exhaust gas stream downstream of the second power turbine, wherein a portion of the fuel line is positioned so that fuel receives heat from the heat exchanger; and
wherein a gear ratio (GR) is defined by a ratio of the second rotation speed to the first rotation speed,
wherein a combination of the first power turbine and the second power turbine includes a number of blade rows (NBR), and
wherein NBR and GR fit a system effective control (SEC) relationship defined as:
S
E
C
=
(
4
N
B
R
)
[
(
(
-
1
2
0
N
B
R
)
(
1
G
R
-
1
)
2
)
+
3
(
(
1
G
R
2
)
-
1
)
]
,
where 0.2<SEC<0.5.
2 . The engine of claim 1 , wherein the first power turbine is configured to rotate in a first rotational direction; and
wherein the second power turbine comprises a counter-rotating (CR) power turbine that rotates in a second rotational direction that is opposite to the first rotational direction.
3 . The engine of claim 2 , wherein the second power turbine is adjacent to the first power turbine without a vane structure between the first power turbine and the second power turbine.
4 . The engine of claim 1 ,
wherein 0.32<SEC<0.43.
5 . The engine of claim 1 , wherein the portion of the fuel line positioned along the heat exchanger is positioned prior to fuel injection into the gas combustion system such that the heat received from the heat exchanger induces a vaporization of the fuel.
6 . The engine of claim 5 , wherein the fuel comprises a cryogenic fuel.
7 . The engine of claim 1 , wherein at least the second power turbine causes a reduction in an exhaust Mach number (EMN) of the exhaust gas stream, following the second power turbine, such that the exhaust Mach number is less than or equal to 0.25 at the heat exchanger.
8 . The engine of claim 7 , wherein the second power turbine is controlled to implement the gear ratio (GR) and produce the exhaust Mach number (EMN), at the heat exchanger, of 0.2<EMN<<0.25.
9 . The engine of claim 1 , further comprising:
an exhaust system coupled downstream of the second power turbine and defining an exhaust path configured to direct the exhaust gas stream away from the second power turbine, and the exhaust path further comprises a bend collector positioned prior, in the exhaust path, to the heat exchanger.
10 . The engine of claim 9 , wherein the first power turbine is secured and rotates about an engine centerline and has a first radius;
the second power turbine is secured and rotates about the engine centerline and has a second radius;
wherein a first portion of the exhaust path, downstream of the bend collector, extends generally parallel with the engine centerline at a first radial distance from the engine centerline that is greater than the first radius and greater than the second radius, and wherein the heat exchanger is operatively coupled with the first portion of the exhaust path.
11 . The engine of claim 10 , wherein the heat exchanger is at least partially positioned within the first portion of the exhaust path to receive the exhaust gas stream.
12 . The engine of claim 1 , wherein the gear ratio (GR) is 0.6<GR<0.97.
13 . The engine of claim 1 , wherein the gear ratio (GR) is 0.78<GR<0.92.
14 . The engine of claim 1 , further comprising:
the first power turbine comprising a high speed power turbine stage comprising between two and eight blade rows.
15 . The engine of claim 14 , further comprising:
the second power turbine comprising a low speed power turbine stage comprising between one and four blade rows.
16 . The engine of claim 1 , further comprising:
a first shaft, wherein the first power turbine is secured with the first shaft;
a second shaft, wherein the second power turbine is secured with the second shaft;
a gear box mechanically cooperated with both the first shaft and the second shaft; and
a propeller mechanically cooperated with and rotationally driven by the gear box as a function of rotation of both the first shaft and the second shaft.
17 . The engine of claim 1 , further comprising:
a first shaft, wherein the first power turbine is secured with the first shaft;
a second shaft, wherein the second power turbine is secured with the second shaft;
a gear box mechanically cooperated with the first shaft;
a propeller mechanically cooperated with and rotationally driven by the gear box as a function of a rotation of the first shaft; and
a generator mechanically cooperated with and rotationally driven by the second shaft.
18 . A method of operating a propulsion system, comprising:
delivering a fuel to a gas combustion system of an engine;
operating a first power turbine at a first rotation speed, wherein the first power turbine is positioned downstream of the gas combustion system and at least partially positioned within an exhaust gas stream downstream of the gas combustion system;
operating a second power turbine at a second rotation speed that is less than the first rotation speed, wherein the second power turbine is at least partially positioned within the exhaust gas stream downstream from the first power turbine, wherein the second rotation speed establishes a gear ratio (GR) defined by a ratio of the second rotation speed to the first rotation speed;
and
heating the fuel within a portion of the fuel line from convected heat from a heat exchanger positioned to receive at least a portion of the exhaust gas stream downstream of the second power turbine;
wherein a combination of the first power turbine and the second power turbine includes a number of blade rows (NBR); and
wherein NBR and GR fit a system effective control (SEC) relationship defined as
S
E
C
=
(
4
N
B
R
)
[
(
(
-
1
2
0
N
B
R
)
(
1
G
R
-
1
)
2
)
+
3
(
(
1
G
R
2
)
-
1
)
]
where 0.2<SEC<0.5.
19 . The method of claim 18 , wherein the operating the first power turbine at the first rotation speed further comprises rotating the first power turbine in a first rotational direction; and
wherein the operating the second power turbine at the second rotation speed further comprises rotating the second power turbine in a second rotational direction that is opposite to the first rotational direction.
20 . The method of claim 18 ,
wherein 0.32<SEC<0.43.