CA2814222A1

CA2814222A1 - System and method for enhancing engine performance

Info

Publication number: CA2814222A1
Application number: CA2814222A
Authority: CA
Inventors: Lev Valdman
Original assignee: LV TECHNOLOGIES Ltd
Current assignee: LV TECHNOLOGIES Ltd
Priority date: 2009-07-12
Filing date: 2010-07-11
Publication date: 2011-01-20
Also published as: WO2011007303A4; IL199803A0; IL199803A; WO2011007303A1

Abstract

A system and method for enhancing the performance of a gas turbine engine or a diesel engine, the system comprising: an air control valve (32) for diverting a portion of compressed air from the air compressor section; a monitoring and control system (12) for monitoring engine and environmental parameters, controlling operation of the engine, and controlling the air control valve (32); a heat exchanger (38) for exchanging heat between compressed air diverted by the air diverter valve and incoming fuel from the fuel supply (22), in order to pre-heat the incoming fuel and cool the diverted air; a first auxiliary turbine (43), receiving the diverted air cooled by the heat exchanger; and an ejector (47) for injecting air exiting the first auxiliary turbine (43).

Description

SYSTEM AND METHOD FOR ENHANCING ENGINE PERFORMANCE
RELATED APPLICATIONS
[001] The present invention claims priority from Israel Patent Application 199803 filed 12 July 2009.
FIELD OF THE INVENTION

[002] The present invention relates to gas turbine and diesel engines, in particular a system and method improving engine efficiency.
BACKGROUND OF THE INVENTION

[003] A gas turbine system generally comprises a compressor for compressing combustion air, a fuel system for supplying a fuel to a combustion chamber where the fuel is mixed with the compressed combustion air and then ignited to form high temperature combustion gases. The combustion gases are exhausted from the combustion chamber to drive a turbine. Introducing higher density (compressed) air to the combustion chamber increases the efficiency and power output of the gas turbine.

[004] Diesel engines generally comprise a block with a plurality of cylinders and combustion chambers, an inlet manifold for supplying air to the combustion chambers, an exhaust manifold for conducting exhaust gases away from the chambers, a turbo compressor comprising a turbine inlet which is connected to the exhaust manifold and a compressor outlet which is connected to the inlet manifold to pressurize the air entering the combustion chambers.

[005] Many factors affect engine performance and a number of systems have been disclosed for enhancing engine performance. One such system is described, for example, in US

6,701,710; 6,726,441; 7,124,591; and 2006/254280 wherein enhanced engine performance is achieved by recirculation of a portion of the compressor outlet air back to the compressor air inlet for introducing this cooled air portion into the total combustion air flow during high power operation and introducing a heated air portion into the total combustion air flow or into the steam generator during start up.
[006] Another type of system is described, for example, in US 6,442,942;
6,854,278;

7,065,953; and 2007/084212, which relate to improving the capacity of a gas turbine particularly at high ambient temperatures, by increasing air density using subsystems for:
a) pre-compression of inlet air with a supercharging fan driven by an electric motor or a mechanical connection to the turbine. In this case the fan can supply a design static pressure of more than 2.0 kPa; and/or b) inlet air is cooled by evaporative fog technologies by injecting treated water into the inlet air flow. It is known that an inlet combustion air temperature decrease of 1.0 degree C results in a gas turbine power increase about 0.7-1.0 %.
[007] US 6,966,745; 7,284,377; 7,254,950; 7,398,642; and 2005/160736 provide examples where cooled air is introduced after a first compressor (to produce a denser air flow) into the inlet of a second compressor to provide increased air mass flow and efficiency of the gas turbine. US 7,398,642 relates to cooled inlet air flow by vaporization of liquid natural gas using inlet air flow compressed between a first compressor and a second compressor.

[008] US 6,499,302; 6,993,913; 7,143,581; and 2003/000218 relate to performance enhancement of a gas turbine by pre-heating the fuel prior to entering into the combustion chamber, using heat emitted by exhaust gases or high pressure air from an air compressor as a heating source.

[009] US 5,937,830; 5,988,265; 6,868,838; and 2006/0124113 disclose the performance enhancement of diesel engines by injecting cooled fuel into the combustion chamber of diesel engines. Fuel is cooled by circulating water or ambient air through an additional passage.

[010] US 7,021,058; 5,904,045; 5,577,385; 5,064,423 and 2004 /0194466 disclose performance enhancement of diesel engines using supercharging systems providing improved combustion air supply during acceleration periods and at low speeds with high torque.

[011] US 5,064,423; 2009/051,167 and 2001/000,091 teach improving engine characteristics during acceleration or start up, or at high ambient temperatures by using secondary combustion air generated by a separate external compressor driven by an auxiliary electric motor.

[012] US 2007/095072 discloses a gas turbine including a compressor for compressing the combustion air, at least one combustion chamber, in which a fuel is burned while compressed combustion air is supplied, and at least one first turbine arranged downstream of the combustion chamber and in which the hot combustion gases from the combustion chamber are expanded to perform work. A portion of compressed combustion air is branched off prior to entering the combustion chamber, pre-cooled by an air cooler, brought to a lower cooling air pressure by a second turbine and supplied to the gas turbine for cooling purposes [013] The above disclosures provide numerous advantages; however, there remains a potential for further improving gas turbine and diesel engine efficiency by improved combustion air supply and treatment of the fuel.
SUMMARY OF THE INVENTION

[014] The present invention relates to an improved system and method for enhancing engine performance, particularly at off-design conditions, by improving the combustion air supply and treatment of the fuel. The system and method are particularly useful for reducing at off-design conditions.

[015] In accordance with embodiments of one aspect of the present invention there is provided a system for enhancing engine performance as defined in claim 1 and its dependent claims.

[016] In accordance with embodiments of one aspect of the present invention there is provided a method for enhancing engine performance as defined in claim 10 and its dependent claims.
BRIEF DESCRIPTION OF THE DRAWINGS

[017] FIG. 1 is a schematic of a gas turbine engine equipped with a first embodiment of a system for enhancing engine performance of the present invention;

[018] FIG. 2 is a schematic of a gas turbine engine equipped with a second embodiment of the present system;

[019] FIG. 3 is a schematic of the gas turbine engine equipped with a third embodiment of the present system;

[020] FIG. 4 is a schematic of the gas turbine engine equipped with a fourth embodiment of the present system;

[021] FIG. 5 is a schematic of the gas turbine engine equipped with a fifth embodiment of the present system;

[022] FIG. 6 is a schematic of the gas turbine engine equipped with a sixth embodiment of the present system;

[023] FIG. 7 is a schematic of the gas turbine equipped with a seventh embodiment of the present system;

[024] FIG. 8 is a schematic of the gas turbine equipped with an eighth embodiment of the present system;

[025] FIG. 9 schematically shows the gas turbine equipped with a ninth embodiment of the present system;

[026] FIG. 10 schematically shows the gas turbine equipped with a tenth embodiment of the present system;

[027] FIG. 11 schematically shows the gas turbine equipped with an eleventh embodiment of the present system;

[028] FIG. 12 schematically shows the gas turbine equipped with a twelfth embodiment of the present system; and [029] FIG. 13 schematically shows a diesel engine equipped with a thirteenth embodiment of the present system.
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[030] Illustrative embodiments of the invention are described below. In the interest of clarity, not all features/components of an actual implementation are necessarily described.

[031] Fig. 1 shows a first embodiment of a gas turbine engine 10 comprising an air compressor section 14, a gas turbine 24 operatively connected in series to the compressor section; and one or more combustion chambers 30 (two shown in the figure) arranged between the air compressor section 14 and the gas turbine 24. Compressor section 14 includes compressor inlet tract 11; a first (low pressure) compressor 15; and a second (high pressure) compressor 16. Combustion chamber 30 is downstream of high pressure compressor 16.

[032] The gas turbine engine 10 is equipped with a performance enhancement system including an electronic control and monitoring (ECM) system 12 comprising sensors for monitoring the gas turbine engine 10 and environment conditions, such as temperature, humidity and the like, and for controlling engine parameters, such as rpm, acceleration, load and so forth, in response to the sensed conditions. The monitoring and control system 12 regulates compressed air recirculation (diverts the compressed air) via a control valve 32 to recirculate/divert a portion of the air from air compressor section 14, for example compressed air exiting high pressure compressor 16, to an air diverter line 31 connected to the outlet of the compressor 16.

[033] The portion of air diverted from air compressor section 14 by control valve 32 enters the diverter line 31. The diverter line 31 passes through a heat exchanger 38 for pre-cooling the diverted compressed air and pre-heating the fuel. In some embodiments, the diverter line 31 includes an electric discharge device 33 for increasing the activity of the air's oxygen molecules and raising the completeness of the oxidation process. Fuel originating at fuel supply 22 enters heat exchanger 38 where it is pre-heated by relatively hot diverted compressed air; this air thus being cooled.

[034] Air exiting the heat exchanger 38 enters a first auxiliary turbine 43, where the air is further cooled and expanded, and continues through an ejector 47. In some embodiments, heat exchanger 38 comprises an additional control device (heater or cooler) for regulating the temperature of the compressed air flow in accordance with desired power of the first auxiliary turbine 43.

[035] In some embodiments, the air then enters a chamber, for example a vortex chamber 17, which is intended to improve the mixing of the cooled air portion exiting the heat exchanger 38 with the general combustion air flow made up of primary ambient air, represented by arrow P, and, in some embodiments supplemented by auxiliary ambient air, represented by arrow X.

[036] Ambient air enters an auxiliary air compressor 41, for compressing a secondary combustion air supply, and continues through a second auxiliary turbine 42 from which this air enters compressor inlet tract 11 of air compressor section 14. Auxiliary air compressor 41 and first auxiliary turbine 43 compose an auxiliary turbo compressor 40. In some embodiments, the general or primary ambient air P, typically filtered, enters air compressor section 14, aided (pressurized by) by a supercharging fan 13.

[037] According to some embodiments, second auxiliary turbine 42 and/or ejector 47 can be connected to tract 11 (optionally to chamber 17) via a pneumatic diode (not shown); and can be operably connected to fan 13 via a gear 48. In some embodiments, part of tract 11 has perforations or slots and is equipped with vanes (not shown) oriented to ensure swirling to improve mixing of the ambient air and cooled recycle/diverted air. As a variant, air exiting ejector 47 is sent to an auxiliary exhaust ejector (not shown) at the outlet of the gas turbine, functioning like a suction pump to reduce gas turbine back pressure.

[038] Fig. 2 shows a second embodiment of gas turbine 10 which is generally similar to that of Fig. 1. However, first auxiliary turbine 43 is operably connected to fan 13 (e.g. via gear 48) without an intermediate compressor (such as auxiliary air compressor 41) and without an intermediate turbine (such as second auxiliary turbine 42), whereby some of the energy from first auxiliary turbine 43 is used to aid in the operation of fan 13.

[039] A modification of this embodiment is also illustrated in Fig. 2 wherein instead of all the cooled air exiting first auxiliary turbine 43, some is piped to an additional ejector 47a and then into an exhaust ejector 18. Exhaust ejector 18 is disposed at gas turbine 24; in particular at a nozzle (not shown) thereof; or between an exhaust diffuser and a heat recovery steam generator thereof (not shown). Exhaust ejector 18 operates in effect as a suction pump reducing the back pressure of gas turbine 24.

[040] A further modification is illustrated in Fig. 2 wherein a portion of the cooled air exiting ejector 47 is piped directly to the second compressor 16.

[041] Fig. 3 shows another embodiment of the gas turbine 10 wherein auxiliary air compressor 41 is connected to tract 11 via an auxiliary intercooler 34, for cooling auxiliary air X
exiting compressor 41; and ejector 47, directly or through vortex chamber 17;
and second auxiliary turbine 42, gear 48 and supercharging fan 13 are absent. According to one modification of this embodiment, ejector 47 is connected to the inlet of the second compressor 16; at the compressor inlet, outlet or both. For humidity reduction, inlet combustion air flow tract 11 can be equipped with a conventional anti-moisture device. By other variants, air exiting intercooler 34 can be connected between compressors 15 and 16; the outlet of auxiliary air compressor 41 can be connected, with or without ejector 47, to an additional exhaust ejector (not shown) disposed within a nozzle (not shown) of the turbine 24 or between an exhaust diffuser (not shown) and a heat recovery steam generator (not shown) in the case of a steam turbine.

[042] Fig. 4 shows an embodiment of gas turbine 10 using both the cooled recycle/diverted air) and energy from the fuel (for example, natural gas, liquefied natural gas, oil, etc.). Recirculated compressed air flows to an ejector 60 for secondary combustion air supply. Ejector 60 is disposed between heat exchanger 38 and tract 11. In some embodiments, ejector 60 is constituted by a series of ejectors. Ejector 60 comprises: an inlet 65 for intake of ambient air as well as the intake of cooled compressed recirculated air exiting heat exchanger 38, via a nozzle 37; a mixing chamber 66 for mixing the ambient air with the recirculated air;
and an ejector outlet 67 operably connected to tract 11, for example via a pneumatic diode 35.
According to a modification of this embodiment, an evaporative cooling device 56 is disposed adjacent the ejector's inlet 65.

[043] Fig. 5 shows an embodiment of the gas turbine 10 similar to that of Fig. 1;
however, auxiliary air exiting auxiliary compressor 41 is piped to the outlet of compressor 16, thus bypassing tract 11; rather than this air being sent to second auxiliary turbine 42. In some embodiments, this design also includes an auxiliary air inlet heater exchanger 44 for heating auxiliary inlet air prior to auxiliary air compressor 41. Heat exchanger 44 can use electric energy or heat emitted from part of the compressed air or exhaust gas.
[044] Figs. 6-9 show embodiments of the gas turbine 10 wherein natural gas is the fuel and a portion thereof is diverted to enhance performance.

[045] Fig. 6 shows an embodiment wherein a portion of natural gas fuel entering at 53 is diverted by a fuel control valve 56 to a heat exchanger 57 to heat or cool that gas to a desired temperature as dictated by the requirements of first auxiliary turbine 43.
Diverted natural gas exits heat exchanger 57 and continues as described above, i.e. via first auxiliary turbine 43 and ejector 47 prior to entering tract 11. As a variant, a portion of the fuel exiting ejector 47 is shunted to second compressor 16.

[046] Fig. 7 shows a modification of the embodiment of Fig. 6 wherein there is no auxiliary compressor 41 and no second auxiliary turbine 42.

[047] Fig. 8 shows another modification of the embodiment of Fig. 6, however wherein downstream of auxiliary air compressor 41 there is intercooler 34, followed by an ejector, for example like ejector 47. As a further variant (labeled "variant 2" in the figure), some or all of the air that exits auxiliary intercooler 34 bypasses both ejector 47 and tract 11, and enters compressor 16.

[048] Fig. 9 shows a further modification of the aforementioned embodiments, however wherein auxiliary air is preheated in a heat exchanger or heater 44, and air exiting compressor 41 bypasses tract 11 and is connected to combustion chamber 30 via a mixing valve 88.

[049] Fig. 10 shows an embodiment of the gas turbine 10 similar to Fig. 2, however some of the auxiliary air exiting auxiliary compressor 41 flows via gas turbine 43, then through heat exchanger 38 before entering exhaust ejector 18. Also, there is a combustion or exhaust gas recycle line 80 for directing a portion of the combustion exhaust gas from gas turbine 24 to gas turbine 43; the quantity of exhaust recycle controlled by a combustion recycle control valve 90.
In a variant, the air exiting heat exchanger 38 can be connected by an ejector (not shown) to exhaust ejector 18 disposed within a turbine nozzle or between an exhaust diffuser and a heat recovery steam generator.

[050] Fig. 11 shows an embodiment of the gas turbine 10 similar to a combination of the embodiments of Fig. 3 and Fig. 10.

[051] Fig. 12 shows an embodiment of the gas turbine 10 similar to Fig. 9 however without ejector 37, wherein air exiting auxiliary compressor 41 is piped to the inlet of combustion chamber 30; and it comprises a combustion exhaust recycle as in Figs. 10 and 11.

[052] Fig. 13 is a schematic depiction of an embodiment of a diesel engine comprising a block 25; an inlet manifold 50; an exhaust manifold 55; and a turbo compressor 65 comprising a turbine 85 and a compressor 78. Turbine 85 is driven by exhaust gas energy received from exhaust manifold 55. Turbine 85 in turn drives compressor 78 via a rotor shaft.
Turbine 85 receives diesel engine exhaust at its inlet. Compressor 78 comprises a compressor inlet tract 48, for suction of ambient air, and an air compressor outlet 49.
Air compressor outlet 49 is operably connected to an air intake port of an inlet manifold 50 via intercooler 52. Fuel from fuel supply 22 is cooled in heat exchanger 38 after which it is fed to inlet manifold 50 via a high pressure fuel injection pump 72. A portion of compressed and cooled air exiting intercooler 52 is diverted to a recycle line 60. The quantity of air recycled is controlled by control valve 32.

[053] Recycle air continues through electric discharge device 33 to turbine 43 from which it enters heat exchanger 64 to cool the fuel from fuel supply 22.
Ambient air X enters auxiliary compressor 41 of auxiliary turbo compressor 40 and flows through intercooler 34 and pneumatic diode 35 prior to entering compressor 78 turbo compressor 65 where this air mixes in inlet tract 48 with primary air P and recycled air from heat exchanger 64.
Diesel engine 20 comprises an electronic control and monitoring (ECM) system, analogous to ECM
12.

[054] Operation of the engine 10, 20 during acceleration and transient periods are characterized by delayed combustion air supply causing dynamic performance decrease. At such engine conditions the ECM 12 system monitors acceleration (gear fuel injection or fuel flow acceleration, or angular acceleration of the engine's rotor shaft or crankshaft, or intake air depression acceleration or general combustion air flow acceleration which are forerunner parameters in the beginning of said engine operation) and uses this information to rapidly signal control valve 32, 56, 90 thereby providing, diverting, recycling ¨ or a combination thereof ¨ of combustion air and/or fuel to provide dynamic performance enhancement.

[055] It should be understood that the above description is merely exemplary and that there are various embodiments of the present invention that may be devised, mutatis mutandis, and that the features described in the above-described embodiments, and those not described herein, may be used separately or in any suitable combination; and the invention can be devised in accordance with embodiments not necessarily described above.

Claims

1. A system for enhancing engine performance, the system comprising:
a gas turbine section comprising:

an air compressor section (14) having an air compressor inlet tract (11) and at least one compressor (15, 16);

a gas turbine (24), operatively connected in series with the at least one compressor (15, 16);
a combustion chamber (30) arranged between the air compressor section (14) and the gas turbine (24);

a fuel supply (22) for providing fuel to the combustion chamber (30), and further comprising an engine enhancing system comprising:

an air control valve (32) for diverting a portion of compressed air from the air compressor section (14);

a monitoring and control system (12) for monitoring engine and environmental parameters, controlling operation of the engine (10, 20), and controlling the air control valve (32);

a heat exchanger (38) for exchanging heat between compressed air diverted by the air diverter valve (32) and incoming fuel from the fuel supply (22), in order to pre-heat the incoming fuel and cool the diverted air;

a first auxiliary turbine (43), receiving the diverted air cooled by the heat exchanger (38); and an ejector (47) for injecting air exiting the first auxiliary turbine (43).

2. The system of claim 1, further comprising an auxiliary air compressor (41) operably connected to the auxiliary turbine (43).

3. The system of claim 2, further comprising a second auxiliary turbine (42) downstream of the auxiliary air compressor (41).

4. The system of claim 1, further comprising a supercharging fan (13) at the inlet of the air compressor section (14).

5. The system of claim 4, wherein further the supercharging fan (13) is turned via a second auxiliary turbine (42) or via auxiliary turbine (43).

6. The system of claim 1, further comprising a chamber (17) for mixing diverted compressed air portion and secondary combustion air with the general combustion air entering the air compressor section (14).

7. The system of claim 1, further comprising an electric discharge device (33) for increasing the activity of the oxygen molecules in the air diverted via control valve (32).

8. The system of claim 1, further comprising an auxiliary exhaust ejector at the outlet of the gas turbine, functioning like a suction pump to reduce gas turbine back pressure.

9. The system of claim 2, further comprising an intercooler (34) for cooling auxiliary air (X) exiting auxiliary air compressor (41).

10. A method for enhancing engine performance comprising:
(a) monitoring engine and environmental parameters;
(b) diverting a portion of compressed air from an air compressor section of the engine in accordance with the monitored engine and environmental parameters;
(c) exchanging heat between the diverted compressed air and incoming fuel for cooling the air and heating the fuel;
(d) passing the diverted air through a first auxiliary turbine; and (e) passing the diverted air from the first auxiliary turbine back to the compressor section of the engine.

11. The method of claim 10, step (b) is performed at off-design conditions.

12. The method of claim 10, further comprising treating the diverted compressed air with an electric discharge device.

13. The method of claim 10, further comprising mixing the diverted compressed air portion and secondary combustion air with primary air in a vortex mixing chamber prior.

14. The method of claim 10, further comprising introducing auxiliary air into the compressor section or a combustion chamber, via an auxiliary air compressor operably connected to the first auxiliary turbine.

15. The method of claim 10, further comprising pre-heating the auxiliary air prior to the auxiliary into the auxiliary air compressor.