WO2010000285A1

WO2010000285A1 - Exhaust-gas energy utilization by means of an open gas turbine process

Info

Publication number: WO2010000285A1
Application number: PCT/EP2008/005433
Authority: WO
Inventors: Stefan Pischinger
Original assignee: Fev Motorentechnik Gmbh
Priority date: 2008-07-03
Filing date: 2008-07-03
Publication date: 2010-01-07
Also published as: DE112008003879A5

Abstract

The invention relates to a method for operating an internal combustion engine 11 with the conversion of thermal exhaust-gas energy into mechanical power, in which method heat is transferred from the exhaust-gas flow of the internal combustion engine 11 to the pre-compressed gaseous medium of an open gas turbine process in a heat exchanger 26 arranged between a compressor 22 and a gas turbine 23, wherein the mechanical power of the gas turbine process is supplied to a working machine.

Description

Exhaust gas energy utilization by open gas turbine process

description

The invention relates to a method for operating an internal combustion engine, wherein the thermal energy of the exhaust gas stream is converted into mechanical power, as well as an internal combustion engine with system components for the application of the method.

In an internal combustion engine, only a relatively small proportion of the energy chemically bound in the fuel used is converted into mechanical power, while a comparatively large proportion is discharged uselessly into the environment via the exhaust gas heat flows and the cooling water heat flows of the internal combustion engine. As far as internal combustion engines are considered for use in vehicles, the proportion of the mechanical energy used for the vehicle drive in relation to the applied chemically bound energy of the fuel is even lower, although the radiation heat losses, engine friction losses and transmission losses are relatively low.

With the increasing shortage and increase in the price of fossil fuels, the increase in the overall efficiency of internal combustion engines, including the use of exhaust gas energy, is becoming increasingly important.

In the publication "Waste heat recovery options for motor vehicles", Michael Hoetger, Jörg Collisi; 11th Session "The work process of the internal combustion engine" 20/21. September 2007 describes how the exhaust heat of an internal combustion engine by means of a closed steam cycle process (Ranki ne cycle) can be used, wherein in an exhaust gas steam heat exchanger, the feed water of the steam cycle process is evaporated and the steam energy is used in an axial piston or plunger machine. As a condenser here, a further heat exchanger can be used in front of the feedwater pump, which is located in the normal cooling water circuit of the internal combustion engine.

The system described here is relatively expensive. Based on this, the present invention is therefore based on the object of providing a method for utilizing the exhaust gas energy of an internal combustion engine and an internal combustion engine of the type mentioned above, which can be represented with low construction costs.

The solution to this problem consists in a method of operating an internal combustion engine converting thermal exhaust gas heat into mechanical power, in which the heat extracted from the exhaust gas flow is supplied to the gaseous medium of an open gas turbine process between a compressor and a gas turbine, wherein the mechanical power of the gas turbine process for Drive a work machine is used.

The use of the open gas turbine process requires significantly simpler components than a closed steam cycle, since no pressure-resistant heat exchangers or seals and in particular no capacitor is required. The gas turbine is much cheaper than a steam turbine.

At relatively low construction and cost of the overall efficiency of the internal combustion engine is improved.

In a particular embodiment, the pre-compressed gaseous medium at least temporarily heat from a combustion process in a before the

Gas turbine arranged combustion chamber exclusively or in addition to be supplied. This is especially true in a cold start phase of the internal combustion engine. In addition, certain boost functions for the driven by the gas turbine engine working machine can be represented thereby easier.

In a preferred embodiment, the compressor can be coupled directly to the turbine of the gas turbine plant and driven by it. In this embodiment, the other embodiments relate.

Alternatively, however, it is also possible to constantly externally drive the compressor of the gas turbine plant, e.g. by an electric motor or by mechanical coupling of the internal combustion engine itself.

Air is used as the working medium of the open gas turbine process. After a first process control is provided that the exhaust gas stream of the engine heat is removed behind the turbine of an exhaust gas turbocharger of the internal combustion engine and fed to the working fluid of the gas turbine process. As a result, sufficient energy is available for driving the exhaust gas turbocharger in the exhaust gas line in each operating state. Moreover, the design changes in existing engine concepts are easier to make, since the heat exchanger of the gas turbine plant can be arranged relatively motorfem.

According to an alternative embodiment, the exhaust gas stream heat can be supplied before the turbine of the exhaust gas turbocharger after the working fluid of the gas turbine process, ie the heat exchanger of the gas turbine plant must be very close to the engine, for example, integrated in the exhaust manifold. This has the advantage that at full load cooling of the exhaust stream and thus a component protection of the turbine of the exhaust gas turbocharger of the internal combustion engine and the components for the exhaust aftertreatment (catalysts) takes place. However, in the case of acceleration from partial load or similar operating conditions, at low load, during idling and during coasting, heat extraction from the exhaust gas is not permitted, so that the drive and the acceleration of the exhaust gas turbocharger is not impaired. That is, the corresponding heat exchanger must be bypassed in phases by the exhaust gas or the flow of the working medium of the gas turbine plant through the heat exchanger must be interrupted in phases. Appropriate control means are provided in the corresponding cable guides. This leaves sufficient energy for the drive of the exhaust gas turbocharger and thus for the undisturbed operation of the internal combustion engine available in case of need.

Of course, it is also possible to combine the two aforementioned possibilities, i. Insert heat exchanger in the exhaust line in front of and behind the turbine of the exhaust gas turbocharger, which can be flowed through by the working medium of the gas turbine plant in series or alternatively individually. However, this requires a higher construction cost.

In an internal combustion engine with exhaust gas recirculation cooled exhaust gas behind the heat exchanger for exhaust gas recirculation is available in a favorable manner, either for low pressure exhaust gas recirculation (behind ATL turbine) or for Hochdruckangasrückführung (before ATL turbine).

According to a particular implementation of the method is provided that the open gas turbine process is started after a start of the internal combustion engine with foreign energy, initially there is no flow connection between the outlet side of the compressor and the inlet side of the gas turbine and this only upon reaching a starting speed of the compressor and Gas turbine is produced via the heat exchanger. This is true in any case when the compressor is driven directly by the gas turbine.

In practice, this starting process takes place in such a way that the heat exchanger is shut off on the working medium side before entry and after exit, so that in the heat exchanger a gas volume is preheated while the pressure is being increased. The externally driven compressor can blow off the working medium on the pressure side and the turbine can suck in secondary air. Only when the compressor and turbine are at a suitable starting speed is a connection initially established from the heat exchanger to the turbine, which can then indicate a short-term mechanical power to the compressor by means of a pressure pulse from the heat exchanger; is then connected to the input side of the heat exchanger, so that sets a self-sustained gas turbine process.

Specifically, in this case, both the inlet between the heat exchanger and turbine and the return from the compressor to the heat exchanger are not continuously connected at rest of the gas turbine plant are closed in the inlet and outlet to the heat exchanger by valves, so that the heat exchanger on its secondary side to the gas turbine process is completed and the compressor in the gas turbine process is open on both sides. When starting the internal combustion engine, the heating of the gas in the heat exchanger is then waited until a sufficient pressure has built up. Only then does the heat exchanger connect to the turbine so that it is driven by the gas stored in the heat exchanger and, with some delay, the compressor is connected to the heat exchanger in accordance with a "closing" of the open one Gas turbine process once the turbine has reached a sufficient speed to pull the compressor and keep the gas turbine process in motion.

The delay is needed to prevent the gas pressure in the heat exchanger from escaping in the wrong direction. To control the opening of the connection of the

Compressor with the heat exchanger input, the speed of the turbocharger or the pressure behind the compressor can be used. The initially open

Compressor output can at the appropriate time with the

Heat exchangers are connected as soon as the pressure build-up behind the compressor exceeds the pressure in the heat exchanger.

In a preferred embodiment, a gas storage can be provided between the compressor and the turbine, which can be integrated in particular in the secondary side of the heat exchanger.

The power surplus of the gas turbine plant can be absorbed by a working machine in the broadest sense. In this case, an electric machine can be used in the simplest way, in particular as a starter Generator may be formed, on the one hand serves as a starter for the gas turbine plant and on the other hand can run after starting in the generator mode, wherein the electrical energy can be stored in a battery.

Another possibility is to let the compressor drive a chiller or a heat pump from the gas turbine plant. With this embodiment, the possibility can be combined to integrate the evaporator of said chiller or heat pump in the air intake of the engine as an additional intercooler.

Other ways of coupling the gas turbine plant with work machines consist in the drive of compressed air compressors or hydraulic pumps. In particular, in the former case is given by the possibility of pressure storage a high degree of independence of the operation of the available power surplus of the gas turbine plant.

Preferred embodiments of an internal combustion engine according to the invention with gas turbine plant are shown in the drawings.

Figure 1 shows an investment scheme in the basic structure with an arranged behind the turbine of the exhaust gas turbocharger of the internal combustion engine heat exchanger of the gas turbine plant;

Figure 2 shows an investment scheme in the basic structure with a front of the turbine of the exhaust gas turbocharger of the internal combustion engine arranged heat exchanger of the gas turbine plant;

Figure 3 shows an investment scheme similar to Figure 1 with a compressor of a chiller as a consumer of the mechanical power of the gas turbine plant; Figure 4 shows an investment scheme similar to Figure 2 with a compressor of a chiller as a consumer of the mechanical power of the gas turbine plant.

In Figure 1, an investment scheme is shown, which can detect an internal combustion engine 11 with an air intake line 12 and an exhaust line 13. It is a supercharged internal combustion engine with an exhaust gas turbocharger 14, the compressor 15 is located in the air intake 12 of the engine 11 and the turbine 16 is located in the exhaust line 13 of the internal combustion engine. Behind the compressor 15 of the exhaust gas turbocharger 14, a charge air cooler 17 is shown in the air intake line, which may preferably be air-cooled. Compressor 15 and turbine 16 of the exhaust gas turbocharger 14 are mechanically coupled to each other via a shaft 18.

It is also an open gas turbine plant 21 is shown, which includes a compressor 22 and a gas turbine 23, which are mechanically coupled via a shaft 24. A wiring harness 25 connects the pressure side of the compressor 22 to the high pressure side of the gas turbine 23. The compressor 22 sucks in air from the environment as the working medium. The line 25 leads via a heat exchanger 26, which is located in the exhaust line 13 of the internal combustion engine 11 behind the turbine 16 of the exhaust gas turbocharger 14. In the heat exchanger 26, heat is transferred from the hot exhaust gas of the internal combustion engine 11 to the precompressed gas of the gas turbine plant in the wiring harness 25, which is relaxed after the heat supply in the heat exchanger 26 in the turbine 23 of the gas turbine plant 21 and generates an excess of power. A combustion chamber 29 in the wiring harness 25 in front of the turbine 23 can serve as an option for further heat supply to the medium of the gas turbine process. In the wiring harness 25, two valves are indicated, a blow-off and check valve 27 on the pressure side of the compressor and a secondary air and check valve 28 on the high-pressure side of the turbine. These valves 27, 28 are to open for starting the gas turbine plant 21 to the compressor and the turbine and at the same time to close before the heat exchanger and behind the heat exchanger. The startup of the gas turbine plant 21 takes place with external energy via a motor 31, which via a shaft 32 with the Compressor 22 is mechanically coupled. When the unit of compressor and turbine is brought by means of the motor 31 to speed, the turbine-side valve 28 is first closed to the environment and opened between the heat exchanger 26 and turbine 23 with a short time offset, so that a gas burst of preheated gas from the heat exchanger causes a power output of the turbine. Shortly thereafter, the blow-off and shut-off valve 27 of the compressor is closed to the environment, thereby opening the connection between the compressor 22 and the heat exchanger 26, so that now the turbine power driven compressor maintains the gas turbine process under constant heat supply to the working fluid in the heat exchanger. The motor 31 can now receive mechanical power from the gas turbine plant during generator operation.

FIG. 2 shows a similar system diagram as in FIG. 1 comprising an internal combustion engine 11 and a gas turbine installation 21.

In Figure 2, the same details as in Figure 1 are given the same reference numerals. The foregoing description is incorporated by reference in its entirety, also with regard to the mode of action described therein.

The only difference compared to the embodiment of Figure 2 is that the heat exchanger 26 of the gas turbine plant 21 is here in the engine nearer the exhaust line 13 of the engine 11, namely in front of the turbine 16 of the exhaust gas turbocharger 14. The exhaust gas temperature level is in this case in a favorable manner higher than behind the turbine of the exhaust gas turbocharger.

FIG. 3 shows a layout diagram which shows an internal combustion engine 11 with an air intake line 12 and an exhaust line 13. It is a supercharged internal combustion engine with an exhaust gas turbocharger 14 whose compressor 15 is located in the air intake line 12 of the internal combustion engine 11 and whose turbine 16 is located in the exhaust line 13 of the internal combustion engine 11. Behind the compressor 15 of the exhaust gas turbocharger, a charge air cooler 17 is shown in the air intake line, which may preferably be air-cooled. Compressor 15 and turbine ne 16 of the exhaust gas turbocharger 14 are mechanically coupled to each other via a shaft 18.

An open gas turbine plant 21 is furthermore shown, which comprises a compressor 22 and a gas turbine 23, which are mechanically coupled via a shaft 24. A wiring harness 25 connects the pressure side of the compressor 22 to the high pressure side of the gas turbine 23. The compressor 22 sucks in air from the environment as the working medium. The line 25 leads via a heat exchanger 26, which is located in the exhaust line 13 of the internal combustion engine 11 behind the turbine 16 of the exhaust gas turbocharger 14. In the heat exchanger 26 there is a heat transfer from the hot exhaust gas of the internal combustion engine 11 to the pre-compressed gas of the gas turbine plant in the wiring harness 25, which is relaxed after the heat supply in the heat exchanger 26 in the turbine 23 of the gas turbine plant 21 and generates a power surplus. Again, a combustion chamber 29 in the wiring harness 25 in front of the turbine 23 can be used as an option for further heat supply to the medium of the gas turbine process. In the wiring harness 25, two valves are indicated, a blow-off and check valve 27 on the pressure side of the compressor and a secondary air and check valve 28 on the high-pressure side of the turbine. These valves 27, 28 are to be opened to start the Gasturbinenanlage 21 to the compressor and the turbine and at the same time to close before the heat exchanger and behind the heat exchanger. The startup of the gas turbine plant 21 takes place with external energy via a motor 31, which is mechanically coupled via a shaft 32 to the compressor 22. When the unit of compressor and turbine is brought by the motor 31 to speed, the turbine-side valve 28 is first closed to the environment and opened between the heat exchanger 26 and turbine 23 with a short time delay, so that a gas impact of preheated gas from the heat exchanger a Power output of the turbine causes. Shortly thereafter, the blow-off and shut-off valve 27 of the compressor is closed to the environment while the connection düng between compressor 22 and heat exchanger 26 is opened, so that now the turbine power driven compressor maintains the gas turbine process under constant heat supply to the working fluid in the heat exchanger. The motor 31 can now receive mechanical power from the gas turbine plant during generator operation.

In the embodiment shown here, the engine 31 can be decoupled from this after start-up of the gas turbine plant 21. As a consumer of the mechanical performance of the gas turbine plant 21, i. as a working machine in the broadest sense, the compressor 42 of a heat pump or chiller 41 is provided in this embodiment, which has a closed coolant circuit 46 and at which the units compressor 42, condenser 43, throttle 44 and evaporator 45 can be seen. The evaporator 45 is here as another charge air cooler in the air intake 12 of the engine 1 1 and thus contributes to the improvement of the process efficiency of the internal combustion engine as such.

FIG. 4 shows a similar system diagram as in FIG. 3, including an internal combustion engine 11 and a gas turbine plant 21.

In Figure 4 the same details as in Figure 3 are given the same reference numerals. The foregoing description is incorporated by reference in its entirety, also with regard to the mode of action described therein.

The only difference with respect to the embodiment according to FIG. 4 is that the heat exchanger 26 of the gas turbine plant 21 is located closer to the engine in the exhaust line 13 of the internal combustion engine 11, namely in front of the turbine 16 of the exhaust gas turbocharger 14. The exhaust gas temperature level is advantageously higher as behind the turbine of the exhaust gas turbocharger. LIST OF REFERENCE NUMBERS

11 internal combustion engine

12 air intake line

13 exhaust system

14 exhaust gas turbocharger

15 compressors

16 turbine

17 intercooler

18 wave

19

20

21 gas turbine plant

22 compressors

23 turbine

24 wave

25 wiring harness

26 heat exchangers

Tl blow-off and shut-off valve

28 Secondary air and check valve

29 combustion chamber

31 engine

32 wave

41 chiller, heat pump

42 compressor

43 capacitor

44 throttle

45 evaporator

46 coolant circuit

Claims

A method of operating an internal combustion engine (11) by converting thermal exhaust energy to mechanical power, wherein heat from the exhaust stream of the internal combustion engine (11) to the precompressed gaseous medium of an open gas turbine process in one between a compressor (22) and a gas turbine ( 23) arranged heat exchanger (26) is transferred, wherein the mechanical power of the gas turbine process is supplied to a working machine.

2. The method according to claim 1,

characterized,

that the pre-compressed gaseous medium at least temporarily heat from a combustion process in front of the gas turbine (23) is supplied.

3. The method according to any one of claims 1 or 2,

characterized,

in that the compressor (22) is directly driven by the gas turbine (23).

4. The method according to any one of claims 1 to 3,

characterized, that air is used as the gaseous working medium.

5. The method according to any one of claims 1 to 4,

characterized,

that the open gas turbine process after a start of the internal combustion engine (11) is approached with external energy, initially between the outlet side of the compressor (22) and the inlet side of the gas turbine (23) has no flow connection and this only upon reaching a starting speed of the compressor (22) and gas turbine (23) via the heat exchanger (26) is produced.

6. The method according to any one of claims 1 to 5, for operating a supercharged internal combustion engine (11) with an exhaust gas turbocharger (14),

characterized,

that the exhaust gas flow heat is removed behind the turbine (16) of the exhaust gas turbocharger (14) and transferred to the working medium of the gas turbine process.

7. The method according to any one of claims 1 to 6, for operating a supercharged internal combustion engine (11) with an exhaust gas turbocharger (14),

characterized,

that the exhaust gas stream heat is removed from the turbine (16) of the exhaust gas turbocharger (14) and transferred to the working medium of the gas turbine process.

8. Internal combustion engine with means for converting thermal exhaust energy into mechanical power, characterized,

that in the exhaust line (13) of the internal combustion engine (11), a heat exchanger (26) is used, which is part of an open gas turbine plant (21) having a compressor (22) in front of the heat exchanger (26) and a heat exchanger (26) downstream turbine (23).

9. Internal combustion engine according to claim 5,

characterized,

in that a combustion chamber (29) is arranged between heat exchanger (26) and turbine (23).

10. Internal combustion engine according to one of claims 8 or 9,

characterized,

that the compressor (22) and the turbine (23) of the gas turbine plant (21) are mechanically coupled.

11. Internal combustion engine according to one of claims 8 or 10,

characterized,

in that an electric machine (31) is connected as a starter to the compressor (22) of the gas turbine plant (21).

12. Internal combustion engine according to one of claims 8 to 11,

characterized, that behind the compressor (22) of the gas turbine plant (21) a bleed and check valve (27) and in front of the turbine (23) of the gas turbine plant (21) a secondary air and check valve (28) are provided, which are independently controllable.

13. Internal combustion engine according to one of claims 8 to 12,

characterized,

in that in the line (25) of the gas turbine plant (21) between the compressor (22) and the turbine (23) a gas storage is arranged, which in particular secondary side in the heat exchanger (26) is integrated.

14. Internal combustion engine according to one of claims 8 to 13,

characterized,

that with the gas turbine plant (21) of the compressor (42) of a heat pump or chiller (41) is coupled as a working machine.

15. Internal combustion engine according to claim 14, with an exhaust gas turbocharger,

characterized,

that the evaporator (45) of the heat pump or chiller (41) in the air intake line (12) behind the compressor (15) of the exhaust gas turbocharger (14) is arranged.

16. Internal combustion engine according to any one of claims 8 to 15,

characterized, that an electrical machine is connected as a working machine with the gas turbine plant (21), in particular in the form of a starter-generator and at the same time can be used as a starter for the gas turbine process.

17. Internal combustion engine according to one of claims 8 to 16,

characterized,

that the mechanical transmission of a motor vehicle as a working machine, in particular via a converter, with the turbine (23) of the gas turbine plant (21) is coupled.

18. Internal combustion engine according to one of claims 8 to 17,

characterized,

in that a compressed air compressor or a hydraulic pump as a working machine is coupled to the turbine (23) of the gas turbine plant (21).