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Title:
EQUIPMENT FOR GAS TURBINE OUTPUT INCREASING AND EFFICIENCY IMPROVEMENT
Document Type and Number:
WIPO Patent Application WO/2017/036431
Kind Code:
A1
Abstract:
The equipment for increase of output and improvement of efficiency of a gas turbine includes a primary compressor (101) with an impeller for input medium compressing, a combustion chamber (102) for heating the compressed input media and a primary gas turbine (103) with an impeller driven by combustion gases from the combustion chamber (102) and power-connected with the impeller of the primary compressor (101), whereas for heating of the compressed input medium the combustion chamber (102} is provided with an inlet of a fuel mixture from a secondary system (1) for preparation of the fuel mixture by mixing of the fuel with an oxidiser, whereas according to the invention the secondary system (1) includes a secondary gas generator (4) with an inlet (41) of the compressed fuel, with an inlet (42) of the compressed oxidizer and with an outlet (43) of the partly combusted fuel mixture connected with an inlet of a secondary gas turbine (3), whereas the outlet of the secondary gas turbine (3) is connected with the combustion chamber (.102) of the primary gas turbine (103) and the shaft (31) of the secondary gas turbine (3) is power-connected with an equipment (2, 8, 22, 23, 24) for energy consumption. With advantage the shaft (31) of the secondary gas turbine (3) is power-connected with a shaft (21) of an upstream primary compressor (2) for compression of the input medium, the outlet of which is connected with inlet of the primary compressor (101) or with the shaft (221) of the secondary compressor (22) for compressing of the oxidiser, while the inlet of the secondary compressor (22) is connected with the outlet of the primary compressor (101) and the outlet of the secondary compressor (22) is connected with the inlet (42) of compressed oxidiser into the secondary gas generator (4).

Inventors:
OTEVŘEL, Marek (Klatovská 22, Brno, 602 00, CZ)
Application Number:
CZ2015/000099
Publication Date:
March 09, 2017
Filing Date:
August 31, 2015
Export Citation:
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Assignee:
OTEVŘEL, Marek (Klatovská 22, Brno, 602 00, CZ)
International Classes:
F02C3/10; F02C3/22; F02C6/04
Domestic Patent References:
WO1999014473A11999-03-25
Foreign References:
US2592749A1952-04-15
US4058974A1977-11-22
US4729217A1988-03-08
GB2229733A1990-10-03
US5386688A1995-02-07
US0586688A1897-07-20
US6644015B22003-11-11
Attorney, Agent or Firm:
FISCHER & PARTNER INTELLECTUAL PROPERTY S.R.O. (Na Hrobci 294/5, Praha 2, 128 00, CZ)
Download PDF:
Claims:
Patent claims

1. Equipment for increase of output and improvement of

efficiency of a gas turbine, including a primary compressor (101) with an impeller for input medium compressing, a

combustion chamber (102) for heating of the compressed input media and a primary gas turbine (103) with an impeller driven by combustion gases from the combustion chamber (102) and power- connected with the impeller of the primary compressor (101) , whereas for heating of the compressed input medium the

combustion chamber (102) is provided with an inlet of a fuel mixture from a secondary system (1) for preparation of the fuel mixture by mixing of the fuel with an oxidiser,

characterised by that

the secondary system (1) includes a secondary gas generator (4} with an inlet (41) of the compressed fuel, with an inlet (42) of the compressed oxidizer and with an outlet (43) of the partly combusted fuel mixture connected with an inlet of a secondary gas turbine (3), whereas the outlet of the secondary gas turbine (3} is connected with the combustion chamber (102) of the primary gas turbine (103) and the shaft (31) of the secondary gas turbine (3) is power-connected with an equipment (2, 8, 22, 23, 24) for energy consumption. 2. Equipment for increase of output and improvement of

efficiency of the gas turbine according to Claim 1,

characterized by that

the shaft (31) of the secondary gas turbine (3) is power- connected with a shaft (21) of an upstream primary compressor (2) for compression of the input medium, the outlet of which is connected with inlet of the primary compressor (101) .

3. Equipment for increase of output and improvement of efficiency of the gas turbine according to Claim 1 or 2, character zed by that

the line (62) of the compressed oxidiser to inlet (42) of the .secondary gas generator (4) , or the line (72) of the compressed fuel to inlet (41} of the secondary gas generator (4} , pass through a heat exchanger (12) for cooling down of the input medium upstream the inlet into the inlet primary compressor (101) or through a heat exchanger (13) . . Equipment for increase of output and improvement of

efficiency of the gas turbine according to Claim 1,

characterized by that

the shaft (31) of the secondary gas turbine (3) is power- connected with the shaft (221) of the secondary compressor (22) for compressing of the oxidiser, while the inlet of the secondary compressor (22) is connected with the outlet of the primary compressor (101) and the outlet of the secondary compressor (22) is connected with the inlet (42) of compressed oxidiser into the secondary gas generator (4) .

5. Equipment for increase of output and improvement of

efficiency of the gas turbine according to Claim 4,

characte ized by that

the line of compressed fuel to the inlet (41) of the secondary gas generator (4) passes through the heat exchanger (10) for cooling down of the compressed outlet air of the primary compressor (101) upstream the inlet into the secondary

compressor (22) for the oxidiser compressing.

6. Equipment for increase of output and improvement of

efficiency of the gas turbine according to some of the Claims 1 through 5,

characterized by that

the secondary gas generator is provided with injector of inert additive for increasing of volume of the resulting fuel mixture and/or for temperature control of the resulting fuel mixture.

AMENDED CLAIMS

received by the International Bureau on 04 August 2016 (04.08.2016)

Patent claims

1. Equipment for increase of output and improvement of

efficiency of a gas turbine, with a primary compressor (101), with a combustion chamber (102) and with a primary gas turbine (103) with an impeller driven by compressed combustion gases from the combustion chamber (102)

whereas for heating of the compressed input medium the

combustion chamber (102) is provided with an inlet of a fuel mixture from a secondary system (1) for preparation of the fuel mixture by mixing of the fuel with an oxidizer,

whereas the secondary system (1) includes a secondary gas generator (4) with an inlet (41) of the compressed fuel, with an inlet (42) of the compressed oxidizer and with an outlet (43) of the partly combusted fuel mixture connected with an inlet of a secondary gas turbine (3) , whereas the outlet of the secondary gas turbine (3) is connected with the combustion chamber (102) of the primary gas turbine (103),

characterized by that

a shaft (32) of the secondary gas turbine (3) is power-connected with a shaft (21) of an upstream primary compressor (2) for compression of the input medium, the outlet of which is

connected either the with the inlet of the primary compressor (101) or directly with the combustion chamber (102) of the primary gas turbine (103) .

2. Equipment for increase of output and improvement of

efficiency of the gas turbine according to claim 1,

characterized by that

a line (62) of the compressed oxidizer from a pump (61) to inlet (42) of the secondary gas generator (4), or a line (72) from a pump (71) of the compressed fuel to inlet (41) of the secondary gas generator (4), pass through a heat exchanger (12) for cooling down of the input medium upstream the inlet into the inlet primary compressor (101) or through a heat exchanger (13) for gaining some of the flue gas enthalpy content.

3. Equipment for increase of output and improvement of

efficiency of a gas turbine according to the claim 1 or 2, characterized by that

the secondary system (1) includes a secondary gas generator (4) with an inlet (41) of the compressed fuel, with an inlet (42) of the compressed oxidizer and with an outlet (43) of the partly combusted fuel mixture connected with an inlet of a secondary gas turbine (3), whereas the outlet of the secondary gas turbine (3) is connected with the combustion chamber (102) of the primary gas turbine (103) and the shaft (31) of the secondary gas turbine (3) is power-connected with an equipment (2, 8, 22, 23, 24) for energy consumption and as well with the shaft (221) of the secondary compressor (22) for compressing of the

secondary oxidizer, while the inlet of the secondary compressor (22) is connected with the outlet of the primary compressor (101) and the outlet of the secondary compressor (22) is connected with the inlet (42) of compressed oxidizer into the secondary gas generator (4) and the line of compressed fuel to the inlet (41) of the secondary gas generator (4) passes through the heat exchanger (10) for cooling down of the compressed outlet air of the primary compressor (101) upstream the inlet into the secondary compressor (22) for the oxidizer compressing. 4. Equipment for increase of output and improvement of

efficiency of the gas turbine according to any of the claims 1 through 3,

characterized by that

the outlet of the primary turbine (103) is connected with the afterburning chamber (106) and the outlet of the secondary turbine (3) is split in two parts where the first part is connected with the combustion chamber (102) of the primary gas turbine (103) whereas the second part is connected with the afterburning chamber (106) .

5. Equipment for increase of output and improvement of

efficiency of the gas turbine according to the claim 4,

characterized by that.

the second part is connected with the turbine (33) where the outlet of the gas turbine (33) is connected with the

afterburning chamber (106) and the shaft (32) of the gas turbine (33) is power-connected with an equipment (2, 8, 22, 23, 24) for energy consumption.

6. Equipment for increase of output and improvement of

efficiency of the gas turbine according to claim 5,

characterized by that

the shaft (32) of the gas turbine (33) is power-connected with the upstream primary compressor (24) for compression of the input medium, the outlet of which is connected either the with inlet of the primary compressor (101) or with the upstream compressor (2) or directly with the combustion chamber (102) of the primary gas turbine (103).

7. Equipment for increase of output and improvement of

efficiency of the gas turbine according to some of the Claims 1 through 6,

characterized by that

the secondary system (1) includes an internal combustion engine replacing by means of position and functionality either the gas generator (4), or the secondary turbine (3) or the secondary compressor (22) or any combination of thereof.

8. Equipment for increase of output and improvement of

efficiency of the gas turbine according to some of the Claims 1 through 7,

characterized by that

the secondary gas generator (4) is provided with an injector of inert additive for increasing volume of the resulting fuel mixture or for temperature control of the resulting fuel mixture .

Description:
Equipment for gas turbine output increasing and efficiency- improvement

Description

Field of technology

The invention concerns the equipment for the gas turbine output and/or efficiency increasing. The equipment includes the compressor with impeller for the input medium compressing, combustion chamber for heating of the compressed input media, and the primary gas turbine with impeller driven by combustion gases from the combustion chamber, and power-connected with the primary compressor impeller, while for the purpose of compressed input medium heating the combustion chamber is provided with the fuel mixture inlet from the secondary system for the fuel mixture preparation by mixing of fuel with oxidizer.

State of technology

Generally numerous designs of compressor sets for compressing of input air with gas turbines are known. The well-known principle of functioning of the jet engines or gas turbines consists in compressing of the air brought by means of a compressor, which is provided with energy by the gas turbine, driven by isentropic expansion of hot gas. The source of the above hot gas is either partly combusted hot air in case of jet engine or gas turbine, or the usually fuel-rich outwards from the separated gas generator in case of so-called turborocket engine. In practice in many cases it is necessary either to change the thrust e.g. with the jet engines, or to change output, e.g. with the gas turbines in power plants or with the bypass turbojet engines and turboprop engines. For change of thrust or output with the gas turbines various systems of fuel supply support are used, e.g. the liquid injection or afterburning. The general objective is to increase the thermal efficiency of gas turbines and to prevent the undesired combination of simultaneous high

temperatures and high pressures at the gas turbine inlet. The file No. US5386688 shows a set of compressor, for

compressing of inlet air, and a gas turbine, for driving of the generator, where the compressor shaft is power-connected with the gas turbine shaft, and upstream the gas turbine inlet the combustion chamber is arranged for combustion of the fuel mixture and supply of combustion gases into the gas turbine. The compressor-gas turbine set comprises further the chemical recuperator for preheating of the fuel mixture in the heat exchanger by outlet combustion gases of the gas turbine and thermo-chemical transformation of the fuel mixture formed by hydrocarbons and water vapour into a treated fuel mixture rich with hydrogen. Downstream the outlet of partly cooled output combustion gases from the chemical recuperator the steam generator, for further utilisation of output combustion gases waste heat by heating of water by these output combustion gases and its transformation into vapour, is arranged. The steam exhaling from the steam generator is subsequently mixed with fuel, formed by hydrocarbons, into the fuel mixture of steam and hydrocarbons, which is brought to chemical recuperator for endothermic thermo-chemical treatment and the hydrogen-rich fuel mixture treated in this way is led further to the combustion chamber. The objective of the solution according to the file No. US5386688 is to increase thermal efficiency of the gas turbine, to reduce temperature of combustion gases entering the gas turbine and in particular to prevent undesired combination of simultaneous high temperatures and high pressures, to utilise the gas turbine waste heat in the steam generator for production of steam, to treat the fuel mixture for combustion in the combustion chamber in such a way to improve combustion and to reduce content of detrimental substances in outlet combustion gases of the gas turbine. According to the file No. US586688 the solution has the following disadvantages:

1) utilisation of steam as the oxidizer, leading to a relatively low resulting temperature of the fuel mixture, limited from top by the output combustion gases temperature,

2) complex character of the recuperation apparatus working at different pressure levels, and

3) low pressure of the fuel mixture, not providing opportunity for possible isentropic expansion of the fuel mixture into suitable expansion equipment before injection itself into the combustion chamber.

4) The low thermal efficiency of the gas turbine has to be compensated by a cascade of in parallel arranged sets of compressors for compressing of input air and gas turbines.

The objective of the invention is to remove the disadvantages of the existing state of technology and to ensure a set of

compressor for compressing of input air and gas turbine, which will enable bigger thrust or power output of the gas turbine, respectively, controllable within wide range, and improvement of the gas turbine efficiency. Further objective of the invention is a design of a jet engine or gas turbine, which will enable a higher total pressure ratio, or bigger difference between the compressor inlet pressure and at the turbine outlet pressure compared to comparable jet engines or gas turbines,

respectively.

Subject of the invention The disadvantages of the existing state of technology are removed to a substantial rate and the invention of objective is satisfied by the equipment for increase of output and

improvement of efficiency of the gas turbine, which includes the primary compressor with impeller for the input medium

compressing, combustion chamber for heating of the compressed input media, and the primary gas turbine with impeller driven by combustion gases from the combustion chamber, and power- connected with the primary compressor impeller, while for the purpose of compressed input medium heating the combustion chamber is provided with the fuel mixture inlet from the

secondary system for the fuel mixture preparation by mixing of fuel with oxidizer and possibly with other admixtures according to the invention, the substance of which consists in the fact, that the secondary system comprises the secondary gas generator with compressed fuel inlet, with compressed oxidizer inlet and with outlet of the partly combusted fuel mixture, connected with inlet of the secondary gas turbine, while the outlet of the secondary gas turbine is connected with the combustion chamber of the primary gas turbine and the shaft of the secondary gas turbine is power-connected with the power consumption equipment.

With advantage, the secondary gas generator can be provided with injector of a suitable inert admixture (e.g. water or water steam) to increase volume of the resulting fuel mixture and/or reduction or control of temperature of the resulting fuel mixture .

With advantage, the shaft of the secondary gas turbine can be powered-connected with the shaft of the upstream primary compressor for compressing of the input medium, that outlet of which can be connected with the primary compressor inlet.

With advantage, the line of compressed oxidizer can pass to the secondary gas generator inlet through the heat exchanger for cooling of the input medium upstream the inlet into the primary compressor and/or the line of compressed fuel can pass to the secondary gas generator inlet through the heat exchanger for cooling of outlet gases of the primary driving turbine. With advantage, the shaft of the secondary gas turbine can be powered-connected with the shaft of the secondary compressor for compressing of the oxidizer, while the secondary compressor inlet can be connected with the outlet of the primary compressor and the outlet of the secondary compressor can be connected with the inlet of the compressed oxidizer into the secondary gas generator .

With advantage, the compressed fuel line can pass to the secondary gas generator inlet through the heat exchanger for cooling of the line between the outlet of the primary compressor and inlet of the secondary compressor for compressing of the oxidizer .

With advantage, the line of the compressed oxidizer can pass to the inlet of the secondary gas generator or the line of the compressed fuel can pass to the inlet of the secondary gas generator through the heat exchanger for cooling of the input medium upstream inlet into the inlet primary compressor or through the heat exchanger.

The invention idea consists in combination of utilisation of the partly combusted hot air and the fuel -rich outlet from the separated gas generator in a single system, which results in increasing of the total pressure ratio, or in increasing of the difference between the compressor inlet pressure and the turbine outlet pressure. In case of modification of the jet engine or of the gas turbine such modification will result in increased thrust or output, respectively, or in the system total

efficiency increase. According to the invention the equipment for the gas turbine output increasing always consists of the primary "classic" subsystem of the gas turbine and secondary additional subsystem of the gas generator. In principle, the primary subsystem utilises the surrounding gaseous media as the oxidizer and as a rule it works in the mode rich with oxidizer (in the lean-burn mode) with respect to temperature limitations of material. That secondary subsystem utilises the compressed fuels in a form of compressed gases, compressed liquids or supercritical liquids, respectively. The above fuels are preheated or partly combusted in the generator in the rich-burn mode, and subsequently expanded in the turbine. The combustion gases rich with hydrogen and possibly other reduction gases are injected into the combustion chamber and/or into the

afterburning and they serve partly or completely as the primary subsystem fuel. Output of the secondary subsystem can be utilised either for further compression of the primary air stream, e.g. by means of the low-pressure compressor, as shown in Figure 2, or also in other secondary auxiliary subsystems, requiring power input, possibly it can be utilised for

additional production of power, e.g. by means of an electric set. Moreover, the waste heat from the primary subsystem may be utilised with advantage for preheating or reforming,

respectively, of the brought secondary flow of fuels, e.g. by means of a heat exchanger. Moreover, the brought and/or

partially compressed primary flow of air can be pre-cooled by the secondary fuels, e.g. by means of a heat exchanger.

Changes of thrust or output can be reached by choking or even by complete closing of one or both the above subsystems.

The system can be equipped with the fluid injection; e.g. of the oxidizer, inert admixture or their mixture; into the primary system before compression to the purpose of cooling of the brought air, or to further increase the thrust or the maximum operating ceiling, as provided e.g. in the file No. US6644015. Liquidised air can be contemplated as the secondary oxidizer, with a triple benefit. First, it is the directly available source of oxygen, second, it may serve for precooling of the primary air flow e.g. by means of a heat exchanger, third, it may serve as a mechanism of the unit output balancing, since in time of low consumption the excessive capacity of the unit can be utilised for increased production of liquid air, and the liquid air stored in this way can be subsequently used again in case of an increased need. Moreover, this system can be designed in such a way that it will need no extra starting system, if the gas generator subsystem has the self-start ability. Pressure increase in the primary system induced in those faces of compressing, which drive the secondary expansion equipment, can provide the sufficient pressure gradient for starting of the primary flow subsystem.

The advantage of the equipment for increase of output and improvement of efficiency of the gas turbine according to the invention consists in increased output and improved efficiency of the gas turbine and in the fact, that it utilises the gas generator products for partial compression in a phase of a low- pressure, intermediate-pressure or a high-pressure compression or in their arbitrary combination. Further advantage is

utilisation of secondary products of the gas generator as the additional output source. Further advantage of the equipment for increase of output of the gas turbine according to the invention is the self-starting ability of the gas turbine.

Summary of figures on the drawings

The equipment for increasing of the gas turbine output according to the invention is illustrated by the drawings as follows:

Fig. 1 connection of the secondary system in the basic

arrangement ,

Fig. 2 connection of the secondary gas turbine with the upstream primary compressor,

Fig. 3 connection of the secondary gas turbine with the

secondary compressor for compressing of the oxidizer.

Fig. 4 connection of the heat exchanger for cooling of the input medium,

Fig. 5 connection of the secondary system in the aircraft

driving unit Examples of execution

The examples of execution provided do not represent the only examples of execution and their combinations or modifications can be considered as further alternatives of the design

presented .

According to Fig. 1, which shows the basic principle and quick upgrade of the existing systems, the equipment for increase of output and improvement of efficiency of the gas turbine includes the primary compressor 101 with impeller for the input medium compressing, combustion chamber 102 for heating of the

compressed input media and the primary gas turbine 103 with impeller driven by combustion gases from the combustion chamber 102 and power-connected with the primary compressor 101

impeller. The outlet gases from the primary gas turbine 103 are led to the driving turbine 104, which mechanically drives the alternator 105. For combustion of the compressed input medium the combustion chamber 102 is provided with the fuel mixture inlet from the secondary system 1 for preparation of the fuel mixture by mixing of fuel with the oxidizer. The secondary system 1 includes the secondary gas generator 4 with inlet 41 of the compressed fuel, with inlet 42 of the compressed oxidizer and with outlet 43 of the partly combusted fuel mixture. The outlet 43 of the partly combusted fuel mixture is connected with inlet of the secondary gas turbine 3. The outlet of the

secondary gas turbine 3 is connected with the combustion chamber 102 of the primary gas turbine 101 and the shaft 31 of the secondary gas turbine 3 is power-connected with the■ power consumption equipment, which is the alternator 8. The liquid fuel is stored in liquid fuel storage tank 7, which is connected with the pressure pump 71, supplying the compressed fuel to inlet 41 of the secondary gas generator 4. The liquid oxidizer is stored in storage tank 6, which is connected with the pressure pump 61, supplying the compressed oxidizer into inlet 42 of the secondary gas generator 4. With advantage, the fuel stored in the storage tank 7 is liquid one and before injection into the combustion chamber 102 of the gas turbine 103 it is first compressed to a high-pressure degree (1-100 MPa, more suitably to 5-50 MPa, even more suitably to 10-30 MPa) , partly combusted with the secondary oxidizer, supplied by the pressure pump 61 into the gas generator 4, which produces the reduction, fuel-rich gas mixture of necessary temperature, e.g. 600-2000 K or more suitably 900-1400 K, which is partly expanded in the secondary expansion turbine 3 to a pressure close to the operating pressure of the combustion chamber 102. Part of the enthalpic content, gas mixture, is delivered to the secondary expansion turbine 3 during expansion and subsequently utilised in alternator 8, which finally leads to increase of total efficiency and capacity of the system. The arrangement according to Fig. 1 can be used advantageously for modernising of the already existing jet engine or gas turbine, in principle without the necessity of any principle modifications of the original equipment .

According to Fig. 2, which shows increase of efficiency due to higher pressure at outlet from the primary turbine, the

secondary system 1, similarly as in Fig. 1, includes the secondary gas generator 4 with inlet 41 of compressed fuel, with inlet 42 of compressed oxidizer and with outlet 43 of the partly combusted fuel mixture, connected with inlet of the secondary gas turbine 3. The outlet of the secondary gas turbine 3 is connected with the combustion chamber 102 of the primary gas turbine 103. Shaft 31 of the secondary gas turbine 3 is power- connected with the shaft 21 of the upstream primary compressor 2 for compression of the input medium, the outlet of which is connected with inlet of the primary compressor 101. The

arrangement according to Fig. 2 can be utilised with a new or existing jet engine or gas turbine by installing of the pre- compression system and in this way it is possible to increase the capacity of the original equipment up to several times, together with increasing of the compression ratio and/or pressure at outlet from the primary turbine, which results in increased thermal efficiency of the system. The fuel from storage tank 7 is first pressurised, partly combusted and expanded in a way, which was shown in Fig. 1. However, in this case the secondary gas turbine 3 is not driving the alternator, but the upstream primary compressor 2, which compresses the brought primary flow of air before it's entering the primary compressor 101. If the primary system 100 is the already used turbine, it has to be modified for higher values of absolute pressure, forces and force moments acting on the turbine components, however, the geometry, volumetric flow and pressure ratio may almost always remain without any change, only it is necessary to satisfy higher temperature of the air brought.

According to Fig. 3, which shows utilisation of compressed air as the secondary oxidiser, the shaft 32 of the secondary gas turbine 3 is power-connected with the shaft 221 of the secondary compressor 22 for compressing of the oxidiser, while the inlet of the secondary compressor 22 is connected with outlet of the primary compressor 101 and the outlet of the secondary

compressor 22 is connected with inlet 42 of the compressed oxidiser into the secondary gas generator 4. With advantage, the equipment is provided with the system of heat exchange, formed by the heat exchangers 10-11, with the purpose to pre-cool the gaseous oxidiser, which is taken from the outlet of the primary compressor 101 and brought to inlet of the secondary compressor 22. With advantage, the line 72 of the compressed fuel passes through the first heat exchanger 10, in which the compressed fuel flowing through the line 72 cools down the heat carrier, which flows into the second heat exchanger 11, in which the heat carrier formed by the compressed fuel cools down the compressed inlet medium, which is taken from the outlet of the primary compressor 101 and brought to inlet of the secondary compressor 22. According to Fig. 3 a smaller part of the outgoing primary air flow, compressed in the primary compressor 101 of the gas turbine 103, is further compressed in the high-pressure

compressor 22, to serve as an oxidiser of the secondary flow instead of a special liquid oxidiser, which was the case of the design according to Fig. 1 and Fig. 2. Before compressing in the secondary compressor 22 it is possible to cool down the air by the heat exchanger 11, which transfers heat into flow of the compressed fuel 72. The merit of this specific design consists in the fact that no external source of oxidiser is required. Moreover, similarly as in case of Fig. 1, this schematic can be used with advantage for modernising of the already existing jet engine or gas turbine, in principle without the need of any principal modifications of the original equipment.

According to Fig. 4, which shows the optimal schematic of equipment with a maximum efficiency, the oxidiser, which is the liquid air, is led from the storage tank 6 of the secondary liquid oxidiser into the oxidiser pump 61, which brings the oxidiser into a high-pressure condition. From the pump 61 the compressed oxidiser line passes through the heat exchanger 12 for cooling down of the input medium upstream the inlet into the primary compressor 101. The compressed oxidiser is led from the heat exchanger 12 further to oxidiser inlet 42 of the secondary gas generator 4. Also the fuel, taken from the liquid fuel storage tank 7 and compressed by the fuel pump 71, is led by the fuel line 72 into the heat exchanger 13 before it enters the inlet 41 of the secondary gas generator 4. Also the oxidiser line 63 passes through the heat exchanger 13 before the oxidiser enters the inlet 42 of the secondary gas generator 4. Finally, through the heat exchanger 13 passes the outlet pipeline from the primary driving turbine 104, which pipeline is cooled down and thus the temperature of gases, going out from the driving turbine 104 into the ambient environment, is being reduced. According to Fig. 4 the equipment exploits fully potential of the idea in power engineering. As it was already mentioned, the liquid air offers itself as the secondary flow oxidiser, with a triple benefit. First, it is the directly available source of oxygen, second, it may serve for precooling of the primary air flow by means of the low-temperature heat exchanger 12, which reduces the energy demands for compression of the primary medium, and third, it may serve for balancing of the energy output, as it was already described. After compression and preheating in heat exchanger 12 it is suitable to heat the secondary flow air further in the high-temperature heat

exchanger 13. The fuel is also preheated and possibly reformed in heat exchanger 13, before it is led into the secondary gas generator 4 for partial combustion with the secondary,

originally liquid, air and for usual expansion in the secondary gas turbine 3 , to which it will hand over considerable part of its enthalpic content. The above modifications may lead to marked increase of thermal efficiency of the unit compared to classic gas turbines of comparable parameters. The energy needed for liquidising of air may originate either from the system itself (consumed in periods of energy demand} , or from a suitable renewable source or from other irregular external energy source . Fig. 5 shows the example connection of the secondary system in the aircraft driving unit or in a driving unit for a cosmic space plane. The equipment according to Fig. 5 includes the secondary gas generator 4 with inlet 41 of compressed fuel, with inlet 42 of compressed oxidiser and with outlet 43 of the partly combusted fuel mixture, which is connected with inlet of the secondary gas turbine 3. Outlet of the secondary gas turbine 3 is connected partly with the combustion chamber 102 of the primary gas turbine 103 and partly with inlet of further, additional secondary gas turbine 33. The connection according to Fig. 5 can be considered a driving unit suitable in particular for supersonic, or hypersonic, respectively, military and civil space shuttles. The on-board secondary propellants, fuel and secondary oxidiser are as always compressed to a value higher than the operating pressure of the combustion chamber 102, partly combusted in the rich-burn mode in the secondary gas generator 4 and subsequently expanded in the secondary gas turbine 3, which drives the low-pressure upstream primary compressor 23. Subsequently the secondary flow is divided. One part is led into the combustion chamber 102 and the other part is further expanded in the additional secondary gas turbine 33, which drives the intermediate-pressure compressor 24 up to reaching of the operating pressure of the additional combustion chamber 106. In the additional combustion chamber 106 it meets the hot primary flow, as a rule rich with oxidiser, to the purpose of complete combustion and, if possible, with

optimisation of the total specific impulse. To prevent damage to the primary compressor 101, and to increase efficiency, it is possible to cool down the primary, partly compressed flow of air, e.g. by means of the heat exchanger 11. For the same purpose it is possible to inject a liquid into the primary flow of air before compression, best an oxidising liquid. During flight off the planetary atmosphere it is possible to switch the whole system smoothly into a purely rocket mode by first closing of the sealable inlet of air 108 and in case of need by starting the evaporator 111. The evaporated injection liquid, e.g. the liquid oxygen, then serves as the primary oxidiser. Differently from other designs , considered, the design according to Fig. 5 doesn't require liquid hydrogen as fuel, which improves the impulse density of the system and eliminate the issue of treating the highly cryogenic propellants, and at the same time it preserves the key property of the markedly higher specific impulse compared to the purely rocket mode. List of key terms

1 secondary system

2 upstream primary compressor

21 shaft

23 low-pressure upstream primary compressor

24 intermediate-pressure upstream primary compressor

22 secondary compressor of oxidizer

221 shaft

3 secondary gas turbine

31 shaft

32 shaft

33 additional secondary gas turbine

4 secondary gas generator

41 fuel inlet

42 oxidizer inlet

43 outlet

5 secondary compression section

6 liquid oxidizer storage tank

61 pump

62 line

7 liquid fuel storage tank

71 pump

72 line

8 alternator

10 heat exchanger

11 heat exchanger

12 heat exchanger

13 heat exchanger

100 primary system

101 primary compressor

102 combustion chamber

103 primary gas turbine 104 primary driving turbine

105 alternator

106 afterburning

108 sealable inlet

109 injection system

110 injection liquid storage tank

111 evaporator