WO2014161661A1

WO2014161661A1 - Method and combined heat and power generation system comprising an internal combustion engine for carrying out said method

Info

Publication number: WO2014161661A1
Application number: PCT/EP2014/000878
Authority: WO
Inventors: Axel Widenhorn; Thilo KISSEL; Dominik LEBKÜCHNER
Original assignee: Dürr Systems GmbH
Priority date: 2013-04-05
Filing date: 2014-04-02
Publication date: 2014-10-09
Also published as: DE102013005764A1

Abstract

The invention relates to a method for operating an internal combustion engine in a combined heat and power generation system (1) and to a combined heat and power generation system (1) comprising an internal combustion engine of this type. The combined heat and power generation system (1) comprises the internal combustion engine which has a combustion chamber system (8), a force conversion device (3) which has a drive-connection to the internal combustion engine, a waste-heat device which is supplied by the internal combustion engine, a recuperator (5) comprising at least one bypass line (6, 7) which can be controlled with regard to a flow rate and a control unit (20). In a first operational state a fuel mass flow rate conducted into the combustion chamber system (8) is set such that a first mechanical output is made available to the drive device and a first thermal output is made available to the waste heat device. If the thermal output requirements of the heat consumer change in relation to the first operational state, a second operational state is brought about, the flow rate through the at least one bypass line (6, 7) being increased if the thermal output requirements become higher and being decreased if the thermal output requirements become lower; and/or in order to bring about the second operational state, the fuel mass flow rate conducted into the combustion chamber system (8) is increased if the thermal output requirements become higher and is decreased if the thermal output requirements become lower, in particular substantially in step with the change in the flow rate through the at least one bypass line (6, 7).

Description

Method and combined heat and power system with an internal combustion engine for carrying out the method

The invention relates to a method for operating an internal combustion engine in a combined heat and power system and a combined heat and power system with such an internal combustion engine for carrying out the method.

For the decentralized supply, for example, of companies with electrical, thermal and / or mechanical energy increasingly combined heat and power systems are used, which are operated with an internal combustion engine, in particular in the form of a micro gas turbine. Such micro gas turbines are gas turbines of the lower power class, ie up to about 500 kW nominal power. Combined heat and power systems of this type include in a known design in addition to the internal combustion engine itself nor a drivable by the internal combustion engine power converter, in particular in the form of an electric generator and a waste heat for the use of waste heat contained in the exhaust gas of the internal combustion engine.

Typically, a micro gas turbine is based on a single shaft system with the compressor, turbine and generator mounted on a central shaft. For a good economy, a high fuel efficiency is imperative. As a measure to increase the fuel efficiency, the mentioned micro gas turbines are provided with a recuperator. The recuperator is a heat exchanger usually integrated in the system in which the thermal energy of the exhaust gas is transferred to the compressed combustion air. The compressed in the compressor and thus preheated combustion air is thus in the recuperator further heated. In the combustion chamber of this compressed and preheated air fuel is supplied and burned, whereby the temperature further increases. By relaxing the resulting exhaust gas in the turbine, this energy is converted into mechanical energy, which drives the compressor and generator.

Conventional micro gas turbine systems are currently being optimized to an operating point, so that in the case of full load, the electrical efficiency as well as the release of thermal energy is maximum. In practice, however, there is a varying demand, in particular for thermal energy, which is obtained from the exhaust gas flow. In conventional micro gas turbines, however, it is not possible, starting from the optimized operating point with constant electrical power, the thermal energy of the exhaust gas, such as by increasing the temperature to increase further. The following disadvantages are listed in this context:

The system is designed and optimized for one operating point.

It is not possible, with the same electrical power, to adapt the thermal power to changing / increased requirements.

Flexibility is only given by partial load. In this case, both the output of electrical and thermal energy decreases. In partial load but the electrical efficiency is reduced and the thermal efficiency increased disproportionately, while the micro gas turbine does not work in its total optimized operating point.

The recuperator ensures both the combustion air as well as the

Exhaust gas mass flow for a pressure drop, which has a negative effect on the electrical efficiency.

The invention is therefore based on the object to provide an operating method for an internal combustion engine in a cogeneration system, by means of which an improved fuel efficiency can be achieved with varying heat requirement.

This object is achieved by a method having the features of claim 1.

The invention is further based on the object of specifying a combined heat and power system with an internal combustion engine, which has an improved fuel efficiency with varying heat demand.

This object is achieved by a combined heat and power system with the features of claim 9.

According to the invention, it is provided that the combined heat and power system with a controllable fuel mass flow supplied internal combustion engine, a drive connected to the internal combustion engine force transducer, in particular a generator, a powered by the internal combustion engine waste heat, in particular for heating an optional heat exchanger, a recuperator with at least a controllable with respect to a flow bypass line and a control unit comprises. The associated operating method according to the invention comprises the following method steps, wherein the control unit is designed to carry out the method in the cogeneration system with these steps:

In a first operating condition, a fuel mass flow leading into the combustion system is adjusted to provide a first mechanical power to the power take-off device and a first thermal power to the waste heat device;

When compared to the first operating state changing thermal power requirement of the heat user, a second operating state is brought about, including the flow through the at least one bypass line with increasing thermal Power requirement is increased and reduced with decreasing thermal power consumption;

And / or for bringing about the second operating state, in particular substantially synchronously with the change in the flow through the at least one bypass line, the fuel mass flow leading into the combustion chamber system is increased with increasing thermal power requirement and reduced with decreasing thermal power requirement.

The invention. Design and process concept allows for the same electrical power a larger thermal performance is provided with improved fuel efficiency. The partial load capacity is also significantly extended, since a low electrical or mechanical output, a high thermal output is made possible. These two variables were previously more interdependent in their dependence. The variety of possible operating states is considerably expanded. The internal combustion engine can be integrated even more in the processes. The use of the bypass lines leads to lower pressure losses in the flow guide, whereby a possible reduction in the electrical efficiency due to lack of recuperation can be at least partially compensated. Transient processes with changing temperature requirements can be carried out with good fuel efficiency.

Under certain conditions of use, it may be appropriate to use both the

mechanical as well as the thermal power output to vary or adapt to the actual needs. Preferably, however, the fuel mass flow is adjusted such that the first mechanical power of the first operating state remains at least approximately the same even in the second operating state. This counteracts typical system requirements, in which the mechanical or electrical power requirement is at least approximately constant, while the thermal power requirement of the heat user can be subject to significant fluctuations. This is possible realize for example by a simple control or map control. Preferably, the fuel mass flow is adjusted by means of a closed control loop such that the mechanical power is adjusted independently of the operating state to an at least approximately constant value. With little effort, a high accuracy of the power control and the temperature control in the system can be achieved.

The internal combustion engine may be a piston engine or the like and is preferably designed as a gas turbine device, in particular as a micro gas turbine. The gas turbine apparatus or the micro gas turbine has a combustion chamber system, a turbine arranged on a turbine shaft and fired by the combustion chamber system, and a compressor, which is preferably arranged non-rotatably on the turbine shaft. The compressor is designed and configured to supply the combustor system with a compressed oxidant stream, in particular a compressed combustion air stream. The combustion chamber system has at least one controllable fuel supply. The recuperator is provided and configured to transmit at least part of the thermal power of an exhaust gas flow of the combustion chamber system to the oxidant flow. For this purpose, the following method steps are provided:

The micro gas turbine is initially operated in the first operating state, in which by the exothermic reaction by means of the combustion chamber a reference temperature in the exhaust gas flow, in particular a turbine outlet temperature of the exhaust gas flow in the amount of a defined nominal temperature prevails, and at the output side of the recuperator in the region of the waste heat a useful temperature of the Exhaust gas flow prevails;

To bring about the second operating state, the fuel mass flow is adjusted substantially in synchronism with the adaptation of the flow through the at least one bypass line in such a way that a change in the Reference temperature to the target temperature is at least partially counteracted.

Instead of the turbine outlet temperature, another reference temperature, such as the turbine inlet temperature or the combustion chamber temperature, may also be selected. Regardless of the aim is to set on the respective reference temperature, a certain combustion temperature in the combustion chamber or in the combustion chamber system or to keep them within certain limits. It may be sufficient to increase the fuel mass flow only to the extent that the combustion chamber temperature does not fall below a certain lower limit as a result of the bypass insert. The fuel mass flow is preferably adjusted in such a way that the reference temperature is kept at the approximately constant value at the setpoint temperature. This ensures that the internal combustion engine or the micro gas turbine is operated at its design operating point with optimum fuel efficiency.

It may be expedient to maintain the combustion chamber temperature at least approximately within a desired tolerance via suitable control logic of control valves and the control unit. In an advantageous development, the at least one bypass line has an actuator drivable or adjustable control, in particular a control valve or a control valve for controlling the gas flow, wherein a leading to the combustion chamber fuel line via an actuator drivable or adjustable control, in particular a control valve, a control valve and / or a fuel injector for controlling the fuel flow, wherein the control unit is operatively connected to the control of the at least one bypass line and the control element of the fuel line, and preferably wherein the control of the at least one bypass line, the control element of the fuel line, the control unit and in particular a temperature sensor Part of a closed loop for regulation the mechanical power output of the internal combustion engine are. With such a control loop can be achieved a very accurate temperature control, as a result, the efficiency of the micro gas turbine and the combined heat and power system remains optimal overall even with varying, transient heat requirements.

In a preferred embodiment, the bypass line is designed as a cold air bypass for bypassing the combustion air area. In the event of a change in the thermal power requirement, the useful temperature of the exhaust gas flow is adjusted by changing the combustion air flow through the cold air bypass. The cold air bypass and its control operates at relatively low temperatures, so that its thermal load is low and the structural design can be kept simple.

In an expedient alternative, the bypass line is designed as an exhaust bypass for bypassing the exhaust area. In the event of a change in the thermal power requirement, the useful temperature of the exhaust gas flow is adjusted by changing the exhaust gas flow through the exhaust gas bypass. The thermal design of the recuperator requires reliability in the case of closed bypass lines, in which case the heat load of the recuperator is highest. Proceeding from this, opening the exhaust gas bypass leads to a reduction in temperature and thus to a reduction in the temperature load. This makes it easy to keep the design simple and increase the life.

In a further preferred embodiment, both a cold air bypass and an exhaust gas bypass are provided. Here, a control or regulation of the combustion chamber temperature is carried out by coordinated and mutual adjustment of the fuel mass flow and the flow rates through the two bypass lines. In addition to extended possibilities for temperature control of the combustion air flow and the exhaust gas flow, there are also additional possibilities that Temperature control of individual components of the combined heat and power system to control or keep low.

Exemplary embodiments of the invention are described below with reference to the drawing. Show it:

Fig. 1 in a schematic block diagram of an inventively trained

Combined heat and power system with a micro gas turbine, with a recuperator and with a control unit, wherein a combustion air range of the recuperator is bypassed by means designed as a cold air bypass bypass line, and wherein by means of the control unit, the combustion chamber temperature of the micro gas turbine is nachgefühlt with varying flow through the cold air bypass .

2, a variant of the arrangement according to FIG. 1, in which an exhaust area of the recuperator can be bypassed by means of a bypass line formed as an exhaust bypass, and wherein the combustion chamber temperature of the micro gas turbine is tracked by the control unit with varying flow through the exhaust gas bypass,

3 is a schematic block diagram of another inventively designed combined heat and power system both with a cold air bypass according to FIG. 1 and with an exhaust gas bypass according to FIG. 2.

1 shows in a schematic block diagram a first exemplary embodiment of a combined heat and power system 1, which is supplied with a controllable fuel mass flow combustion engine, a drive connected to the internal combustion engine force converter 3, a powered by the internal combustion engine waste heat in particular Heating of an optionally provided heat exchanger 4, a recuperator 5 with at least one controllable with respect to a flow bypass line 6 and a control unit 20 includes. The internal combustion engine may be a piston engine or the like and is in the preferred embodiment shown a gas turbine device, here a micro gas turbine 2. The nominal power of the micro gas turbine 2 is preferably in a range of 25 kW inclusive up to and including 500 kW.

The micro gas turbine 2 is formed as a single-shaft turbine with a central and continuous turbine shaft 19, and further comprises an on the turbine shaft 19 rotationally fixed compressor 17 for an oxidant stream, here combustion air, a combustion chamber system 8 for the combustion of fuel with the 'compacted Combustion air, and a non-rotatably mounted on the turbine shaft 19 and fired by the combustion chamber system 8 turbine 18 for the relaxation of the resulting compressed and hot exhaust gases while obtaining mechanical energy. As a result of the expansion of an exhaust gas flow 16 formed in the turbine 18 by the exhaust gases, the turbine shaft 19 is rotationally driven, which in turn drives the compressor 17 attached to the turbine shaft 19 and the force converter 3 also attached to it or thus driven thereto. The force transducer 3 is in the preferred embodiment shown an electric generator for the production of electrical energy, but may also be another type of engine, for example, to provide mechanical energy or a combination of both. By means of the optionally provided heat exchanger 4, the exhaust gas flow 16 is removed from thermal power and supplied to the heat user. In one embodiment of the waste heat device without heat exchanger 4, the exhaust gas stream 16 can also be used directly, for example, for a drying process.

Specifically, it is provided for a first operating state or initial or normal state described below that by means of the compressor 17 Combustion air is sucked from the environment. It may be appropriate to use this intake combustion air simultaneously as cooling air for the force transducer 3. In this case, the intake combustion air undergoes a first

Preheating. The combustion air is in the compressor to a

Combustion air flow 15 compressed at about 4 bar pressure and preheated to about 220 ° C. The compressed and preheated combustion air stream 15 is passed through a combustion air region 13 of the recuperator 5 and further heated to about 600 ° C, optionally up to 620 ° C.

In this state, the combustion air flow 15 is passed through the combustion chamber system 8, in which also fuel is introduced by means of a schematically indicated fuel line 11. The combustion chamber system 8 is preferably designed for the flameless oxidation of the fuel (FLOX combustion), but can also be designed for a diffusion-based or premixed oxidation. For the preferred FLOX combustion, the combustion chamber system indicated here only schematically is divided in practice into a pilot stage and a downstream main stage. The combustion produces a compressed exhaust gas flow 16 with a renewed increase in combustion chamber temperature. In the first operating state or initial state described here, which also represents the design operating point of the micro gas turbine 2, the combustion chamber temperature on the input side of the turbine 18 is in the amount of a defined nominal combustion chamber temperature of up to 960 ° C. However, the first operating state can also be, for example, in the case of a lower mechanical or electrical energy requirement at the force transducer 3, a partial load state with a lower nominal combustion chamber temperature.

The exhaust stream 16 is expanded in the turbine 18, with its temperature dropping to about 650 ° C. This still hot exhaust gas stream 16 is passed through an exhaust gas region 14 of the recuperator 5 which is fluidically separated from the combustion air region 13 but connected in a heat-transmitting manner. Here is a heat transfer from exhaust gas flow 16 to the combustion air flow 15 instead, wherein the combustion air flow 15 is heated as described above, and wherein the exhaust gas flow 16 is further cooled to a useful temperature of about 300 ° C.

After passing through the recuperator 5, the exhaust gas stream 16 is led to the downstream heat removal device with the optional heat exchanger 4, where a first thermal power is provided to the waste heat device, and where by means of the waste heat device as needed in the exhaust gas stream cooled to useful temperature 16 still included Waste heat can be dissipated and used as thermal energy. At the same time, in the first operating state described here, a first mechanical power is provided at the output device, here at the force converter 3, converted into electrical power in the generator, and supplied to the user.

In the event that a constant heat demand at the heat exchanger 4 occurs at a constant electromechanical energy decrease at the force transducer 3 compared to the above-described initial state, a second operating state is brought about according to the invention, including the temperature of the exhaust gas stream 16 in the region of the heat exchanger 4 is also changed , For this purpose, at least one, in the embodiment of FIG. 1 exactly one with respect to their flow controllable bypass line 6 is provided, which is designed here as a cold air bypass for bypassing the combustion air region 13. The bypass line 6 is provided with a controllable by an actuator or adjustable control element, in particular with a

Control valve 9 or a master key for controlling the Gäsdurchflusses provided, wherein the control valve 9 is connected via an indicated data and control line to the control unit 20 and is driven by the latter. In the now exemplified case of increasing the useful heat demand at the heat exchanger 4 with respect to the first operating state described above, the exhaust gas temperature of the exhaust gas stream 16 by increasing the combustion air flow through the Cold air bypass increased. For this purpose, the control valve 9 via the control unit as needed partially or completely opened, as a result, a more or less pronounced partial flow of the combustion air flow 15, with fully open control valve 9 even approximately the entire combustion air flow 15 is not through the combustion air region 13 of the recuperator 5, but is directed around this. As a result, only a reduced or no amount of heat is removed from the exhaust gas flow 16 in the recuperator 5 more. In the opposite case, that is, compared to the first operating state reduced useful heat demand, the exhaust gas temperature of the exhaust gas stream 16 is reduced by reducing the combustion air flow through the cold air bypass. Depending on the degree of opening of the control valve 9 so the useful temperature of the exhaust stream 16 can be adjusted downstream of the recuperator 5 in a range between the undisturbed temperature already described above directly downstream of the compressor 17 and the useful temperature already described without bypass insert. When the control valve 9 is fully open, the recuperator 5 assumes the temperature of the exhaust gas stream 16, since no heat is dissipated here.

In the leading through the recuperator 5 combustion air duct section, which is bypassed by the bypass line 6, a control throttle 22 is optionally arranged, which is connected via a schematically indicated data and control line to the control unit 20 and is driven by the latter. When the bypass line 6 is closed, the control throttle 22 is kept fully open in order to allow unimpeded flow of the combustion air flow 15 through the recuperator. With increasing degree of opening of the control valve 9 or with increasing flow through the cold air bypass can by means of the control throttle 22, the flow of the combustion air flow 15 through the combustion air region 13 of the

Recuperators 5 are throttled or even stopped altogether to force a certain flow through the cold air bypass. The control throttle 22 is - as shown here - preferably arranged on the input side of the combustion air region 13, but can also be positioned on the output side of it. FIG. 2 shows a variant of the arrangement according to FIG. 1, in which at least one bypass line 7, which is controllable in this case with respect to its flow rate, is likewise provided for the increase of the temperature of the exhaust gas flow 16 as required. In contrast to the bypass line 6 according to FIG. 1, the bypass line 7 according to FIG. 2 is designed as an exhaust gas bypass for bypassing the exhaust gas region 14. The bypass line 7 is provided with a controllable by an actuator or adjustable control, in particular with a control valve 10 or a control valve for controlling the gas flow, the control valve 10 is connected via an indicated data and control line to the control unit 20 and is controlled by the latter , In the case exemplified here of increasing the useful heat demand on the heat exchanger 4, the exhaust gas temperature of the exhaust gas stream 16 is increased by increasing the exhaust gas flow through the exhaust gas bypass. For this purpose, the control valve 10 is partially or fully opened as required by the control unit, as a result, a more or less pronounced partial flow of the exhaust gas stream 16, with fully open control valve 10 even approximately the entire exhaust stream 16 not through the exhaust gas portion 14 of the recuperator 5, but is directed around this. As in the embodiment of FIG. 1, the exhaust gas flow 16 in the recuperator 5 is removed as a result only a reduced or no amount of heat more. In the opposite case, that is, with respect to the first operating state reduced useful heat demand, the exhaust gas temperature of the exhaust gas stream 16 is reduced by reducing the exhaust gas flow through the exhaust gas bypass. Depending on the degree of opening of the control valve 10 so the useful temperature of the exhaust gas stream 16 can be adjusted downstream of the recuperator 5 in a range between the undisturbed temperature already described above directly downstream of the compressor 17 and the useful temperature already described without bypass insert. When the control valve 10 is fully open, the recuperator 5 assumes the temperature of the compressed combustion air flow 15, since no more heat is introduced from the exhaust gas flow 16 here. In the leading through the recuperator 5 Abgaskanal- section, which is bypassed by the bypass line 7, is optionally still a control throttle 23 is arranged, which is connected via a schematically indicated data and control line to the control unit 20 and is driven by the latter. When the bypass line 7 is closed, the control throttle 23 is kept fully open in order to allow unimpeded flow of the exhaust gas flow 16 through the recuperator. With increasing Öffhungsgrad the control valve 10 and with increasing flow through the exhaust gas bypass can be throttled by the control throttle 23, the flow of the exhaust stream 16 through the exhaust region 14 of the recuperator 5 or even completely suppressed to force a certain flow through the exhaust gas bypass. The control throttle 23 is - as shown here - preferably arranged on the output side of the exhaust gas region 14, but can also be positioned on the input side of it.

FIG. 3 shows a further variant of the arrangements according to FIGS. 1, 2, in which two bypass lines 6, 7 controllable with respect to their flow rate are provided for the increase in the temperature of the exhaust gas stream 16, namely the bypass line 6 designed as a cold air bypass The physical design of the bypass lines 6, 7 and the control of the control valves 9, 10 and the control throttles 22, 23 is identical as described above, with the difference that here Both bypass lines are present and operated as needed alternately or in combination with each other. A control or regulation of the combustion chamber temperature is carried out by coordinated and mutual adjustment of the fuel mass flow and the flow rates through the two bypass lines 6, 7. When the control valves 9, 10 are fully open, the recuperator 5 at least approximately assumes the ambient temperature, since neither heat from the combustion air flow 15 nor from the exhaust gas flow 16 is introduced here. In addition to extended possibilities for Temperaturtuhrung the combustion air flow 15 and the exhaust gas flow 16, there are also additional opportunities that

Temperature load of individual components of the combined heat and power system 1 to control or keep low.

Unless otherwise expressly described or illustrated in the drawings, the embodiments of FIGS. 1, 2 and 3 in the other features, reference numerals, properties and details of the Verfahrensfuhrung match.

However, it is in all three Ausfu exemplary embodiments of FIGS. 1, 2 and 3 so that with more or less increasing opening degree of the bypass line 6, 7 not only the useful temperature of the exhaust stream 16 increases, but at the same time

Temperature of the combustion air flow 15 on the output side of the recuperator decreases. This would lead to a decrease in the combustion chamber temperature of the above-described combustion chamber setpoint temperature and thus to a decrease in the mechanical or electrical power output at the force transducer 3 without further measures. Conversely, with decreasing opening degree of the bypass line 6, 7, an increase in the combustion chamber temperature compared to the above-described combustion chamber target temperature and thus an increase in the mechanical or electrical power output at the force transducer 3 would be involved. The micro gas turbine would no longer operate at its optimized operating point corresponding to the above initial state or first operating state with reduced fuel efficiency. Both cases would also counteract the desired change in the useful temperature of the exhaust stream 16.

It is therefore provided according to the invention for bringing about the second operating state, alternatively or in particular in combination with the above-described change in the flow through the at least one bypass line 6, 7, and preferably substantially in synchronism with the change in the flow through the bypass line 6 and / or by the bypass line 7 to change the introduced into the combustion chamber 8 fuel mass flow to a change in the mechanical or electrical power output and / or a change in the combustion chamber temperature counteract the combustion chamber setpoint temperature of the first operating state at least partially. For this purpose, a leading into the combustion chamber system 8 fuel line 11 via an actuator drivable or adjustable control, in particular a control valve 12, a control valve and / or a Brennstoffinjektor for controlling the fuel flow, wherein the control valve 12 also via an indicated data and control line the control unit 20 is connected and is controlled by the latter. By means of the control valve 12, the fuel mass flow can be changed starting from the initial state described above. During combustion, more or less heat energy is released compared to the first operating state, whereby a deviation of the combustion chamber temperature from the nominal combustion chamber temperature is at least reduced. Preferably, the fuel mass flow is changed in its amount so far that the combustion chamber temperature is maintained at least approximately constant on the combustion chamber target temperature.

It may be sufficient to maintain the combustion chamber temperature at least approximately within a desired tolerance via suitable control logic of the control valves 9, 10, 12, the optional control throttles 22, 23 and the control unit 20. Preferably, the at least one control valve 9, 10 of the at least one bypass line 6, 7, the control valve 12 of the fuel line 11, the control throttles 22, 23, the control unit 20 and a temperature sensor 21 form a closed loop. Of the

Temperature sensor 21 is arranged here by way of example at the outlet of turbine 18 for determining the turbine outlet temperature, but may also be positioned at another suitable location, for example at the inlet of turbine 18 or in combustion chamber system 8. In any case, by means of the temperature sensor 21 either directly or indirectly via known thermodynamic relationships the

Combustion chamber temperature and their deviation from the combustion chamber setpoint temperature determined. With such a closed control loop, the combustion chamber temperature is then regulated in particular to the nominal setting of the combustion chamber, whereby a very accurate temperature control is possible.

Overall, the following applies to the design and process concept according to the invention:

The exhaust gas temperatures can be adjusted freely and continuously between about 170 and 670 ° C, preferably between 200 and 650 ° C. As a result, the range of application of the micro gas turbine 2 and thus of the combined heat and power system 1 is considerably increased.

The design and method concept according to the invention makes it possible to provide greater thermal output with improved efficiency for the same electrical output.

The partial load capacity is also significantly extended, since a low electrical or mechanical output, a high thermal output is made possible. These two variables were previously more interdependent in their dependence.

The variety of possible operating states is considerably expanded. The micro gas turbine 2 can be integrated even more into the processes, or can better follow the process requirements.

The use of the bypass lines 6, 7 leads to lower pressure losses in the flow guide, whereby a possible reduction of the electrical efficiency due to lack of recuperation can be at least partially compensated. Transient processes with changing temperature requirements can be carried out with good efficiency.

Claims

claims

1. A method for operating an internal combustion engine in a combined heat and power system (1), wherein the internal combustion engine, a combustion chamber system (8) for the exothermic conversion of a controllable fuel mass flow with a combustion air stream (15) in an exhaust stream (16), a driven device for providing a in the exothermic conversion resulting mechanical power and a waste heat device for providing a in the exothermic reaction in the exhaust gas flow (16) resulting thermal power to a heat user, wherein further with the exhaust gas flow (16) heated recuperator (5) is provided, which a combustion air area (13) for the combustion air flow (15), an exhaust gas region (14) for the exhaust gas flow (16) and at least one bypass line (6, 7) controllable with respect to their flow, the process comprising the following process steps:

In a first operating condition, a fuel mass flow leading into the combustion chamber system (8) is adjusted to provide a first mechanical power to the power take-off device and a first thermal power to the waste heat device;

When compared to the first operating state changing thermal power requirement of the heat user, a second operating state is brought about, for which the flow through the at least one bypass line (6, 7) increases with increasing thermal power consumption and is reduced with decreasing thermal power consumption;

And / or for bringing about the second operating state, in particular substantially synchronously with the change in the flow through the at least one bypass line (6, 7), the fuel mass flow leading into the combustion chamber system (8) is increased with increasing thermal power requirement and reduced with decreasing thermal power consumption.

2. The method according to claim 1,

characterized in that the fuel mass flow is adjusted such that the first mechanical power of the first operating state remains at least approximately the same even in the second operating state.

3. The method according to claim 2,

characterized in that the fuel mass flow is adjusted by means of a closed loop such that the mechanical power is adjusted independently of the operating state to an at least approximately constant value.

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

characterized in that the bypass line (6) is designed as a cold air bypass for bypassing the combustion air region (13), and wherein in the case of a change in the thermal power consumption, the useful temperature of the exhaust stream (16) is adjusted by changing the combustion air flow through the cold air bypass.

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

characterized in that the bypass line (7) is designed as an exhaust bypass for bypassing the exhaust region (14), and wherein in the case of a change in the thermal power demand, the useful temperature of the exhaust stream (16) is adjusted by changing the exhaust gas flow through the exhaust gas bypass.

6. Process according to claims 4 and 5,

characterized in that both a cold air bypass and an exhaust gas bypass are provided, and that a control or regulation of the

mechanical performance by coordinated and mutual adjustment of the fuel mass flow and the flow rates through the two bypass lines (6, 7) is made.

7. The method according to any one of claims 1 to 6,

characterized in that the internal combustion engine is a micro gas turbine (2), that by means of the waste heat device, the waste heat in the exhaust stream (16) of the micro gas turbine (2) is used, and that the following method steps are provided:

The micro gas turbine (2) is initially operated in the first operating state in which by the exothermic reaction by means of the combustion chamber system (8) a reference temperature in the exhaust gas stream (16), in particular a turbine outlet temperature of the exhaust stream (16) in the amount of a defined setpoint temperature prevails, and in the on the output side of the recuperator (5) prevails in the region of the waste heat device, a useful temperature of the exhaust gas stream (16);

In order to bring about the second operating state, the fuel mass flow is adjusted essentially in synchronism with the adjustment of the flow through the at least one bypass line (6, 7) such that a change in the reference temperature with respect to the setpoint temperature is at least partially counteracted. Method according to claim 7,

characterized in that the fuel mass flow is adjusted such that the reference temperature is maintained at least approximately constant at the target temperature.

Combined heat and power system (1) comprising an internal combustion engine supplied with a controllable fuel mass flow, a power converter (3), in particular a generator connected to the internal combustion engine, a heat recovery device fed by the internal combustion engine, in particular for heating an optionally provided heat exchanger (4), a recuperator (5) having at least one bypass line (6, 7) controllable with respect to a flow, and a control unit (20), wherein the control unit (20) is designed to operate in the cogeneration system (1) according to one of the Claims 1 to 8 execute.

Combined heat and power system according to claim 9,

characterized in that the internal combustion engine as a gas turbine device, in particular as a micro gas turbine (2) is designed, which a combustion chamber system (8), on a turbine shaft (19) rotatably disposed and through the combustion chamber system (8) fired turbine (18) and a , preferably on the turbine shaft (19) rotatably mounted compressor (17), wherein the compressor (17) is provided to the combustion chamber system (8) with a compressed oxidant stream, in particular with a compressed combustion air stream (15) to supply the combustion chamber system (8) has at least one controllable fuel supply, and wherein the recuperator (5) is provided to transfer at least part of the thermal power of an exhaust gas flow (16) of the combustion chamber system (8) to the oxidant flow.

11. combined heat and power system according to claim 9 or 10,

characterized in that the at least one bypass line (6, 7) has an actuator drivable or adjustable control element, in particular a control valve (9, 10) or a control flap for controlling the gas flow, and that to the combustion chamber system (8) leading Brermstoffleitung ( 11) has an actuator drivable or adjustable control, in particular a control valve (12), a control flap and / or a fuel injector for controlling the fuel flow, wherein the control unit (20) with the control of the at least one bypass line (6, 7) and the control element of the Brermstoffleitung (11) is operatively connected, and wherein preferably the control of the at least one bypass line (6, 7), the control of the fuel line (11), the control unit (20) and in particular a temperature sensor (21) part of a closed loop to Regulation of the mechanical power output of the Verbrennungskraftmaschi ne are.

12. combined heat and power system according to one of claims 9 to 11,

characterized in that two bypass lines (6, 7) are provided, wherein a bypass line (6) as cold air bypass And a bypass line (7) is designed as · exhaust gas bypass, and that a control or regulation of the mechanical output of the internal combustion engine

coordinated and mutual adjustment of the fuel mass flow and the flow rates through the two bypass lines (6, 7) by means of the control unit (20) is provided.