Method for operating a system

Abstract

Method for operating a system (1), wherein the system (1) has a charge compressor (5), which is designed to heat a flow medium, wherein the system (1) comprises a storage device (9), which is designed to store heat, wherein the heat generated in the charge compressor (5) is transferred to the storage device (9) in a first charging operating state, wherein the charge compressor (5) is heated in an operating state in which no heat for the storage device (9) is generated in the charge compressor (5).

Description

[0001] Description

[0002] Procedure for operating a plant

[0003] The invention relates to a method for operating a system, wherein the system has a charge compressor which is designed to heat a flow medium, wherein the system comprises a storage device which is designed to store heat, wherein in a first charging operating state the heat generated in the charge compressor is transferred to the storage device.

[0004] Thermal energy storage systems are used for heat storage, where thermal energy is first generated and then temporarily stored in the thermal energy storage system. The thermal energy is usually used later to convert it into electrical energy. Ideally, renewable energies such as wind power or solar energy are used to generate the thermal energy. Turbomachines are generally used to generate both thermal and electrical energy. For example, thermal energy can be generated in a compressor, whereas electrical energy can be generated using a turbine or an expander.

[0005] However, it is difficult to predict when the turbomachines used to generate thermal and electrical energy will need to be in operation. For example, if the compressor is not used for a long time while the turbine or expander is in use at the same time, the compressor may cool down below critical temperatures. This extends the time until it can be used in standard operation and reduces its service life due to the repeated cooling and warming up processes. The same applies if the turbine or expander is not used while the compressor is in use. Here, too, the turbine or expander may cool down too much, making warming up to standard operation time-consuming and repeated cooling and warming up processes shorten the service life of individual turbine or expander components.

[0006] Against this background, the invention has set itself the task of specifying a system in which individual components are subjected to less thermal stress.

[0007] This object is achieved by a method for operating a system, wherein the system has a charge compressor which is designed to heat a flow medium, wherein the system comprises a storage device which is designed to store heat, wherein in a first charging operating state the heat generated in the charge compressor is transferred to the storage device, wherein in an operating state in which no heat is generated in the charge compressor for the storage device, the charge compressor is heated.

[0008] The invention enables a turbomachine, such as a compressor or charge compressor in this case, to be kept warm, even if it is not permanently in operation in a system. Nevertheless, in such systems, it is desirable to make the compressor available for standard operation as quickly as possible. Because the compressor, especially the charge compressor, is heated, this charge compressor is available again relatively quickly.

[0009] The invention is based on the idea that , considering the overall balance , it is advantageous to heat the charge compressor using suitable means .

[0010] To reduce these effects, the turbomachines must be kept hot between operating cycles. During load operation, a temperature distribution as close as possible to the temperature profile should be maintained. Advantageous further developments are specified in the subclaims.

[0011] It is therefore advantageous to heat the charge compressor by flowing a warming flow medium through the charge compressor.

[0012] This is a relatively inexpensive way to keep the charge compressor at a desired temperature.

[0013] In a further advantageous development, the charge compressor is heated by using electrical heating mats.

[0014] This measure may be considered as a support in addition to the warming with the warming flow medium.

[0015] In a further advantageous development, the system has a generation turbine which, in a generation operating state, is flowed through by flow medium heated in the storage device, whereby the thermal energy of the flow medium is converted into mechanical energy, whereby in an operating state in which no flow medium heated in the storage device flows through the generation turbine in the generation turbine, the generation turbine is heated.

[0016] Thus, there are two circuits in the system. In one circuit, which can also be referred to as the charging circuit, thermal energy is generated in the charge compressor and temporarily stored in the storage device. Salts can be used as the storage device. The charge compressor is driven by a motor, which in turn is powered by renewable energy such as wind power or solar energy. In the other circuit, which can also be referred to as the generation circuit, electrical energy is generated by the generation turbine. In the generation turbine, the thermal energy temporarily stored in the storage device is converted into mechanical energy. Finally, electrical energy is generated via an electrical generator that is coupled to the generation turbine.

[0017] According to the invention, the charge compressor and the generation turbine are kept warm between the two circuits. The warming temperatures should be as close as possible to the operating temperatures.

[0018] Heating with the warming flow medium can also be called convective heating.

[0019] In an advantageous further development, the charge compressor has a compressor flow inlet through which the flow medium flows into the charge compressor, wherein the flow medium flows through a compressor flow region and flows out of the charge compressor again via a compressor outflow region, wherein in the operating state in which no heat is generated in the charge compressor for the storage device, the heat-keeping flow medium flows through the charge compressor via the compressor flow inlet.

[0020] This measure heats up the thermally stressed components comparatively quickly.

[0021] The rotor should preferably rotate slowly. Rotation at a frequency between 0.2 and 5 Hz, particularly 1 Hz, is advantageous.

[0022] Since the charge compressor and the generation turbine are kept at a substantially constant temperature, it is possible to influence the service life of individual components. The above-described properties, features, and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more readily understood in connection with the following description of the exemplary embodiments, which are explained in more detail in conjunction with the drawings.

[0023] Identical components or components with the same function are marked with the same reference symbols.

[0024] Exemplary embodiments of the invention are described below with reference to the drawings. These are not intended to represent the exemplary embodiments to scale; rather, where useful for explanation, the drawings are presented in a schematic and / or slightly distorted form. For supplements to the teachings immediately apparent in the drawings, reference is made to the relevant prior art.

[0025] It shows :

[0026] Figure 1 is a schematic representation of an embodiment of a system according to the invention

[0027] Figure 2 is a schematic representation of an embodiment of a charge compressor

[0028] Figure 3 is a schematic representation of an embodiment of a generation turbine

[0029] Figure 1 shows a schematic representation of an embodiment of a system 1 according to the invention. The system 1 is designed as described below and is operated as follows. Essentially, the system 1 can be described as having two circuits. In the first circuit, which can also be referred to as the charging circuit, thermal energy is generated from renewable energies 2 and temporarily stored. In the second circuit, which can also be referred to as the generation circuit, the temporarily stored thermal energy is converted into electrical energy.

[0030] Renewable energies 2, such as wind energy or solar energy, are used to drive a motor 3. This motor is connected in terms of torque to a shaft 4 and drives a charge compressor 5. The charge compressor 5 is a turbomachine designed as a compressor and is designed to increase the pressure and temperature of a flow medium. For this purpose, the charge compressor 5 has a rotatably mounted compressor rotor 28 (not shown in Fig. 1) and a compressor housing 29 arranged around the compressor rotor (not shown in Fig. 1). The charge compressor 5 can, for example, be designed as an axial compressor.

[0031] A flow medium flows into the charge compressor 5 via the compressor flow inlet 6, whereby the temperature and pressure of the flow medium are increased during operation. The flow medium can be air, for example. The charge compressor 5 is designed to heat the flow medium.

[0032] Via the compressor outlet area 7, the heated flow medium reaches a storage device 9 via a line 8. The thermal energy of the flow medium is stored in the storage device 9, i.e. after the flow medium has flowed through the storage device 9, it is cooled and flows via a line 10 to a heat exchanger 11, which can also be referred to as a recuperator. After the heat exchanger 11, the flow medium flows via a line 12 to a turbine 13. The turbine 13 can also be referred to as an expander. In the turbine 13, the thermal energy of the flow medium is converted into mechanical energy. The turbine 13 is coupled to the charge compressor 5 and the engine 3 via the shaft 4 so as to transmit torque. Thus, in a first charging operating state, the heat generated in the charge compressor 5 is transferred to the storage device 9.

[0033] In an operating state in which no heat is generated in the charge compressor 5 for the storage device 9, the charge compressor 5 is heated.

[0034] The charge compressor 5 is heated by flowing a heat-retaining fluid through the charge compressor 5. Alternatively or additionally, the charge compressor can be heated or kept warm using electric heating mats.

[0035] The flow medium, expanded and cooled in the turbine 13, flows via a line 14 to a heat exchanger 15, which is provided with a cooling medium. The thermal energy of the flow medium is transferred to the cooling medium in the heat exchanger 15. The cooling medium is thereby cooled.

[0036] After the heat exchanger 15, the flow medium flows via a line 16 to the heat exchanger 11 and from there via line 17 back to the compressor flow inlet 6 into the charge compressor 5. The charge cycle is thus closed. As long as renewable energy is available and the storage device 9 has not yet reached its capacity limit, the charge cycle remains active.

[0037] If the capacity limit of storage device 9 is reached or renewable energy sources are not available, the second cycle can now be started. However, the second cycle (generation cycle) is only started when electrical energy is needed. The generation cycle will now be described.

[0038] The thermal energy in the storage device 9 is transferred to the flow medium, from where it flows via a line 18 to a generation turbine 19. In the generation turbine 19, the thermal energy of the flow medium is converted into mechanical energy. Via a shaft 20, the mechanical energy is converted into electrical energy in an electrical generator 21.

[0039] After the generation turbine 19, the expanded and cooled flow medium flows via a line 22 through the heat exchanger 11 and from there via line 23 to the heat exchanger 15. After the heat exchanger 15, the flow medium passes via line 24 to a compressor 25, where the pressure and temperature of the flow medium are increased.

[0040] In the generation turbine 19, the thermal energy of the flow medium is converted into mechanical energy, wherein in an operating state in which no flow medium heated in the storage device 9 flows through the generation turbine 19, the generation turbine 19 is heated.

[0041] The generation turbine 19 is heated by flowing a heat-retaining medium through the generation turbine 19. Alternatively or additionally, the generation turbine 19 can be heated or kept warm using electric heating mats.

[0042] The flow medium flows from the compressor 25 via a line 26 to the heat exchanger 11 and from there via a line 27 back to the storage device 9. The generation cycle is thus closed.

[0043] Figure 2 shows a schematic representation of the charge compressor 5. The charge compressor 5 is designed with a rotatably mounted compressor rotor 28. A compressor housing 29 is arranged around the rotatably mounted compressor rotor 28. A detailed representation of the functioning of a compressor will not be discussed in more detail. During operation, a flow medium flows via the compressor flow inlet 6 through a compressor flow region 30. The compressor flow region 30 comprises compressor blades (not shown in more detail). The heated and pressurized flow medium flows out of the charge compressor 5 again via the compressor outlet region 7.

[0044] In the operating state in which no heat is generated in the charge compressor 5 for the storage device 9, measures are taken to keep the charge compressor 5 in a warm state. This is intended to prepare the charge compressor 5 for a later time in order to be able to put the charge compressor 5 into operation again as quickly as possible in order to generate heat for the storage device 9. For this purpose, a warm keeping flow medium flows through the compressor outlet area 7 such that the temperatures in the charge compressor 5 are such that they are as close as possible to the temperature distribution during operation. The keeping flow medium flowing into the compressor outlet area 7 would lead to excessively high temperatures in the compressor flow inlet 6.Therefore, the warming flow medium flowing in via the compressor outflow area 7 is led out of the charge compressor 5 via a line 31 approximately in the middle of the compression flow area 30.

[0045] The warming flow medium flows in at a lower temperature via the compressor flow inlet 6 and is led out of the charge compressor 5 via a further line 32.

[0046] The warming flow medium can be air and can be warmed or heated using electrical energy. Thus, the warming flow medium serves to keep the charge compressor 5 warm. Even if the charge compressor 5 has cooled down after a prolonged downtime and is in a so-called cold state, the warming flow medium can serve to warm the charge compressor 5. The compressor rotor 28 is rotated slowly while the warming flow medium flows through it.

[0047] Figure 3 shows a schematic representation of a generation turbine 19. The generation turbine 19 comprises a rotatably mounted turbine rotor 33, with a turbine housing 34 arranged around the turbine rotor. During normal operation, the flow medium flows into the generation turbine 19 via an inflow region 35 and out again via the flow path 36, which includes guide vanes and rotor blades, via the outflow region 37. Since this is a two-flow generation turbine 19, two outflow regions 37 can be seen.

[0048] During charging operation, i.e., in an operating state in which the generation turbine 19 is not being used to generate electrical energy, the generation turbine 19 is kept warm by supplying warm heat-retaining flow medium via the inlet region 35. The heat-retaining flow medium flows out again via the outlet region 37. The heat-retaining flow medium can be air. The turbine rotor 33 is thereby set into slight rotation. The resulting temperatures should essentially correspond to the temperatures that also arise during generation operation.

[0049] Although the invention has been illustrated and described in detail by the preferred embodiment, the invention is not limited by the disclosed examples and other variants can be derived by those skilled in the art without departing from the scope of the invention.

Claims

Patent claims 1. Method for operating a system (1), wherein the system (1) has a charge compressor (5) which is designed to heat a flow medium, wherein the system (1) comprises a storage device (9) which is designed to store heat, wherein in a first charging operating state the heat generated in the charge compressor (5) is transferred to the storage device (9), wherein in an operating state in which no heat is generated in the charge compressor (5) for the storage device (9), the charge compressor (5) is heated.

2. Method according to claim 1, wherein the heating of the charge compressor (5) is carried out by flowing through the charge compressor (5) with a warming flow medium.

3. Method according to claim 1 or 2, wherein the heating of the charge compressor (5) is carried out by the use of electrical heating mats.

4. Method according to one of the preceding claims, wherein the plant has a generation turbine (19) which, in a generation operating state, is flowed through by flow medium heated in the storage device (9), whereby the thermal energy of the flow medium is converted into mechanical energy, wherein in an operating state in which no flow medium heated in the storage device (9) flows through the generation turbine (19) in the generation turbine (19), the generation turbine (19) is heated.

5. The method according to claim 4, wherein the heating of the generation turbine (19) is carried out by flowing through the generation turbine (19) with a warming flow medium.

6. Method according to claim 4 or 5, the heating of the generation turbine (19) is carried out by the use of electric heating mats.

7. Method according to one of the preceding claims, wherein the charge compressor (5) has a rotatably mounted compressor rotor (28) and a compressor housing (29) arranged around the compressor rotor (28), wherein the compressor rotor (28) is driven by a motor (3).

8. Method according to one of the preceding claims, wherein the generation turbine (19) has a rotatably mounted turbine rotor (33) and a turbine housing (34) arranged around the turbine rotor, wherein the turbine rotor (33) drives an electric generator (21).

9. Method according to one of the preceding claims, wherein the charge compressor (5) has a compressor flow inlet (6) through which the flow medium flows into the charge compressor, wherein the flow medium flows through a compressor flow region (30) and flows out of the charge compressor (5) again via a compressor outflow region (7), wherein in the operating state in which no heat is generated in the charge compressor (5) for the storage device (9), the warming flow medium flows through the charge compressor (9) via the compressor flow inlet (9).

10. The method according to claim 9, wherein the warming flow medium also flows through the charge compressor (5) via the compressor outflow region (7), wherein the charge compressor (5) is designed such that the warming flow medium flows out of the charge compressor (5) again via the compressor flow region (30).

11. The method according to claim 10, wherein the temperature of the heat-retaining medium flowing through the charge compressor (5) via the compressor outflow region (7) is higher in the region of the compressor outflow region (7) than the temperature of the heat-retaining medium flowing through the charge compressor (5) via the compressor flow inlet (6) in the region of the compressor flow inlet (6).

12. Method according to one of claims 7 to 11, wherein the compressor rotor (28) is rotated during the flow of the heat-retaining medium.

13. Method according to one of claims 8 to 12, wherein the turbine rotor (33) is rotated during the flow through with the heat-keeping medium.

14. Method according to one of the preceding claims, wherein the flow medium is air.

15. A method according to any one of the preceding claims, wherein the warming flow medium is air.

16. The method according to any one of claims 2 to 15, wherein the warming fluid is heated by means of electrical energy.

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