System for energy storage and recovery

Abstract

The invention relates to a system for energy storage and recovery, comprising: at least one compressed-air tank, at least one pressurized-water tank in communication with the compressed-air tank, at least one turbine in effective communication with the at least one pressurized-water tank, a generator for generating electrical energy, a high-pressure pump for pumping water from a water reservoir into the pressurized-water tank. According to one aspect of the invention, the turbine in effective communication with the at least one pressurized-water tank is a reaction turbine, which is connected in series with a constant pressure turbine in such a manner that a drive shaft of the reaction turbine is connected to a drive shaft of the constant pressure turbine and a drive shaft of the generator, and the constant pressure turbine is arranged between the reaction turbine and the generator, wherein the generator includes an interface for connection to a public power grid.

Claims

1. A system for energy storage and recovery, comprising: at least one compressed-air tank (1), at least one pressurized-water tank (2) in communication with the at least one compressed-air tank (1), at least one turbine (3) in effective communication with the at least one pressurized-water tank (2), a generator (4) for generating electrical energy, and a high-pressure pump (11) for pumping water from a water reservoir (9) into the at least one pressurized-water tank (2), wherein the at least one turbine (3) in effective communication with the at least one pressurized-water tank (2) is a reaction turbine, which is connected in series with a constant pressure turbine (3a) in such a manner that a drive shaft (AW) of the reaction turbine (3) is connected to a drive shaft (AW) of the constant pressure turbine (3a) and a drive shaft (AW) of the generator (4), the constant pressure turbine (3a) is arranged between the reaction turbine (3) and the generator (4), and the generator (4) includes an interface for connection to a public power grid (S).

2. The system according to claim 1, wherein the drive shaft of the reaction turbine (3) and the drive shaft (AW) of the constant pressure turbine (3a) form a common shaft, and, either, the drive shaft (AW) of the reaction turbine (3) and the drive shaft (AW) of the constant pressure turbine (3a) are rigidly coupled to each other, or the drive shaft (AW) of the reaction turbine (3) and the drive shaft (AW) of the constant pressure turbine (3a) are connected to each other via a transmission. wherein an outlet of the at least one pressurized-water tank (2) is connected to an inlet of the reaction turbine (3) and an outlet of the reaction turbine (3) is connected to an inlet of the constant pressure turbine (3a).

3. The system according to claim 2, wherein pressure regulation of the inlet pressure of the constant pressure turbine (3a) is via a guide vane arranged between an outlet of the reaction turbine (3) and an inlet of the constant pressure turbine (3a).

4. The system according to claim 1, wherein when a plurality of pressurized-water tanks (2) are provided, a connection line connects outlets of the pressurized-water tanks (2) with one another, and the pressurized-water tanks (2) are arranged in such a manner with respect to one another that the connection line has a gradient and has a sump at a lowest point, which is connected to an inlet of the at least one turbine (3, 3a).

5. The system according to claim 1, wherein a stop valve (6) is provided at an inlet of the at least one turbine (3, 3a).

6. The system according to claim 1, wherein the at least one compressed-air tank (1) is in constant pressure equilibrium with the at least one pressurized-water tank (2), in such a manner that during energy storage and recovery the pressure in the at least one compressed-air tank (1) is equal to the pressure in the at least one pressurized-water tank (2).

7. The system according to claim 1, wherein precisely one pressure line (5) is present between an outlet of the at least one compressed-air tank (1) and an inlet of the at least one pressurized-water tank (2) and is adapted to conduct compressed air from the at least one pressurized-water tank (2) to the at least one compressed-air tank (1) during energy storage and to conduct compressed air from the at least one compressed-air tank (1) to the at least one pressurized-water tank (2) during energy recovery.

8. The system according to claim 7, wherein a stop device is arranged in the pressure line (5), which is configured to block the pressure line (5) at a sudden pressure drop.

9. The system according to claim 1, wherein the ratio of a volume of the at least one pressurized-water tank (2) to a volume of the at least one compressed-air tank (1) is 1:1, 1:2, 1:3, or 1:4.

10. The system according to claim 1, wherein a control and a comparison unit (13) is provided which is configured, as a function of the load on a public power grid (S), to drive the high-pressure pump (11) with energy from the public power grid (S) to pump water from the water reservoir (9) into the at least one pressurized-water tank (2) when there is a surplus of energy in the public power grid (S), or to conduct pressurized water from the at least one pressurized-water tank (2) to the at least one turbine (3, 3a) and to feed the energy generated in the generator (4, 4a) to the public power grid (S), when there is a demand for energy in the public power grid (S).

11. The system according to claim 10, wherein, in the case of energy recovery, the control unit (13) is configured to regulate the power generated by the at least one turbine (3, 3a) by opening or closing of water inlet nozzles (7) connected to the at least one turbine (3, 3a).

12. The system according to claim 1, wherein a control and a comparison unit (13) is provided for comparing a current pressure in the at least one pressurized-water tank (2) and a current pressure in the at least one compressed-air tank (1) and a current water level in the at least one pressurized-water tank (2) with a set pressure value, wherein the control and the comparison unit (13) is configured in such a manner that compressed air is fed from a compressed-air reservoir (18) to the at least one compressed-air tank (1) as a function of the comparison result.

13. A system for energy storage and recovery, comprising: at least one compressed-air tank (1), at least one pressurized-water tank (2) in communication with the at least one compressed-air tank (1), a compressed-air turbine being arranged between the at least one compressed-air tank and the at least one pressurized-water tank (2), a generator (4) for generating electrical energy, and a high-pressure pump (11) for pumping water from a water reservoir (9) into the at least one pressurized-water tank (2), wherein a constant pressure turbine (3a) in effective communication with the at least one pressurized-water tank (2) is a Pelton turbine, the generator (4) is configured for the generation of electrical voltage, the generator (4) is connected to a frequency converter (4a) for the generation of a constant voltage and frequency, and the frequency converter (4a) includes an interface for connection to a public power grid (S).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention as well as further advantages of the invention will be described in the following with reference to figures, in which:

(2) FIG. 1 shows the arrangement of a reaction turbine and a constant pressure turbine in a system for energy storage and recovery according to the present invention;

(3) FIG. 2 shows a system for energy storage and recovery according to the present invention with a combination of a reaction turbine and a constant pressure turbine and, as an example, four compressed-air tanks and four pressurized-water tanks;

(4) FIG. 3 shows a system for energy storage and recovery according to the present invention with, as an example, two groups each consisting of two compressed-air tanks and one pressurized-water tank; and

(5) FIG. 4 shows a system for energy storage and recovery according to the present invention with a Pelton turbine and a frequency converter.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(6) FIG. 1 shows the arrangement according to the present invention of a reaction turbine 3 and a constant pressure turbine 3a in a system for energy storage and recovery according to the present invention. For clarity and for better understanding, FIG. 1 does not show the other components of the system for energy storage and recovery according to the present invention. Reference is therefore made to FIGS. 2 and 3.

(7) The reaction turbine 3, for example a Francis turbine, comprises an inlet E3 and an outlet A3. The inlet E3 is connected to two pressurized-water tank(s) (not shown) via a pressure line 5. The outlet A3 of the reaction turbine 3 is connected to the inlet of a constant pressure turbine 3a, for example a Pelton turbine. The outlet (not shown) of the constant pressure turbine 3a is connected to a water reservoir for storing and capturing the water.

(8) The drive shaft AW of the reaction turbine 3 is connected to the drive shaft AW of the constant pressure turbine 3a. A generator 4 for the generation of electrical energy is also coupled to the drive shaft AW. The drive shaft AW essentially extends centrally through the constant pressure turbine 3a. The drive shaft AW is, in particular, a one-piece drive shaft AW.

(9) Arrows show the direction of flow of the water through the pressure line 5 to the inlet E3 of the reaction turbine 3, between the reaction turbine 3 and the constant pressure turbine 3a.

(10) FIG. 2 shows a system for energy storage and recovery according to the present invention with a combination of a reaction turbine and a constant pressure turbine and, as an example, four compressed-air tanks 1 and four pressurized-water tanks 2. Each pressure tank 1, 2 is advantageously configured as a single-wall tank. Each tank 1, 2 can have a volume of up to 300,000 m.sup.3 and can be rated for a pressure of up to 1000 bar.

(11) Each compressed-air tank 1 comprises an inlet 1e for compressed air and an outlet 1a for compressed air. The inlet 1e of a compressed-air tank 1 is in communication with a compressed-air reservoir 18, which also has the function of a compressed-air compensation vessel. This compressed-air reservoir 18 is connected to the compressor 17 which can feed compressed ambient air to the compressed-air reservoir 18. The compressor 17 is supplied with power by a power grid S connected or connectable to the system. Refilling compressed air from the compressed-air reservoir 18 into a compressed-air tank 1 is carried out as needed, as will be explained below, as determined by a control and comparison unit 13.

(12) The control and comparison unit 13 is connected to a flow control valve 19 via a data line 16. This flow control valve 19 is arranged between the compressed-air reservoir 18 and the compressed-air tank 1, in particular between the outlet of the compressed-air reservoir 18 and the inlet 1e of a compressed-air tank 1. FIG. 2 shows a single flow control valve 19, which is arranged upstream of the inlets 1e of the four compressed-air tanks 1. It goes without saying that it is also possible to arrange one flow control valve 19 at the inlet 1e of each compressed-air tank 1 for the individual control of each compressed-air tank 1. This ensures that during the operation of the system the pressure within the system can be held constant, such as at 500 bar. As will be explained below, the control and comparison unit 13 can be used to determine, on the basis of the water level within the pressurized-water tank determined by means of sensors SN, and the volume available in the compressed-air tank 1 and the pressurized-water tank 2, the amount of compressed air needed for a predetermined pressure, such as 500 bar, which can be refilled as necessary from the compressed-air reservoir 18 through the flow control valve 19 into the compressed-air tank 1. The sensor SD measures the pressure in a compressed-air tank 1. Sensors SD, SN are thus connected to the flow control valve 19 and the control and comparison unit 13 via corresponding data lines 16.

(13) The outlet 1a of the compressed-air tank 1 is connected to the inlet 2e of the pressurized-water tank 2 via a pressure line 5. A stop device 6a, shown diagrammatically in FIG. 2, can be arranged in the pressure line between the compressed-air tank 1 and the pressurized-water tank 2 and configured to block the pressure line at a sudden pressure drop. A compressed-air turbine 3b, shown diagrammatically in FIG. 2, can be arranged between the outlet 1a of the compressed-air tank 1 and the inlet of the pressurized-water tank 2.

(14) The outlet 2a of a pressurized-water tank 2 is connected to the inlet E3 of the reaction turbine 3 via a stop valve 6 and a pressure line 5. With respect to the arrangement of the reaction turbine 3 and the constant pressure turbine 3a reference is made to the explanations regarding FIG. 1. The outlets 2a of the pressurized-water tank 2 are always at the lowest point in the pressurized-water tanks 2. Furthermore, the outlets 2a of the pressurized-water tanks 2 are connected to each other by a common pressure line 5. This pressure line 5 has a gradient in the direction of the turbine arrangement 3, 3a.

(15) The reaction turbine 3 and the constant pressure turbine 3a each have an adjustable set of guide vanes 7, 7a, to enable adjustment of the exit pressure from the reaction turbine 3 into the constant pressure turbine 3a and the inlet amount into the reaction turbine 3 and the constant pressure turbine 3a. By these means the output power of the turbine arrangement 3, 3a can be controlled. For this purpose, the inlet guide vanes 7, 7a are connected to the control and comparison unit 13 via a data line 16. The reaction turbine 3 and the constant pressure turbine 3a are coupled to the generator 4 for power generation via a common drive shaft AW. This generator 4 is connected to a power grid S or connectable to a power grid S.

(16) The arrangement of the reaction turbine 3 and the constant pressure turbine 3a is configured in such a manner that in the case of energy recovery, water passing through the arrangement of the reaction turbine 3 and the constant pressure turbine 3a from the pressurized-water tank 2 is expanded into a water reservoir 9.

(17) The water reservoir 9 has an antechamber 10 for extracting the water in the case of energy storage. This antechamber 10 has an opening 10a which is designed such that the lower edge of this inlet opening 10a is above the bottom of the antechamber 10. The top edge of the opening 10a is below the water level (not shown) in the water reservoir 9. The edge prevents heavy particles in the water from passing into the antechamber 10. By immersing the top edge below the minimum water level, air-containing water is prevented from entering the antechamber which can lead to malfunctions of the high-pressure pump 11 and soiling in the pressurized-water tank 2. The soiling can lead to malfunctions in the turbines 3, 3a. Furthermore, foam present as micro bubbles in the water created by the constant pressure turbine 3a due to water expansion is prevented from passing into the antechamber 10 and to the high-pressure pump 11.

(18) A high-pressure pump 11 is connected to the antechamber 10. The high-pressure pump 11 pumps water from the antechamber 10 into the pressurized-water tank 2 via a connection line 12. The high-pressure pump 11 is supplied with power from the connected or connectable power grid S. Furthermore, a check valve 8 is provided in the connection line 12 between the high-pressure pump 11 and the pressurized-water tank 2. This check valve 8 is for preventing feedback to the high-pressure pump 11 caused by the pressure built up in the pressurized-water tank 2 during energy storage. It goes without saying that the pressurized-water tank 2 can have a stop valve (not shown) at the inlet 2a of the connection line 12 into the pressurized-water tank 2.

(19) The system includes a control and comparison unit 13. This control and comparison unit 13 is connected to pressure sensors SD in the compressed-air tank 1 and level sensors SN in the pressurized-water tank 2 via a data line 16. The control and comparison unit 13 comprises a comparison means for comparing the current pressure in the pressurized-water tank 2, or the current pressure in the compressed-air tank 1 and the current water level in the pressurized-water tank 2 with a set pressure value. The control and comparison unit 13 is configured in such a manner that, as a function of the comparison result, compressed air from the compressed-air reservoir 18 is fed to the compressed-air tank 1 via a flow control valve 19.

(20) The control and comparison unit 13 is connected to a network computer 15 of a connected or connectable public or non-public power grid S via a data line 16. The network computer 15 issues a request to the control and comparison unit 13 as to whether the system should or can be used for energy generation or for energy storage.

(21) For this purpose, the control and comparison unit 13 is connected to the adjustable inlet guide vanes 7, 7a of the turbines 3, 3a via a data line 16. It is thus possible to adjust the power requested from the network computer 15 of the public power grid at the turbines 3, 3a. Furthermore, the control and comparison unit 13 is connected to the stop valve 6 via a data line 16. This ensures that the stop valve 6 is only opened in the case of energy recovery and a connection is established between the pressurized-water tank 2 and the turbines 3, 3a.

(22) Furthermore, the control and comparison unit 13 is connected to a controller (not shown) of the high-pressure pump 11 via a data line 16. It is thus possible to convert the surplus energy made available to the system from the power grid S as needed to use it for pumping water into the pressurized-water tank 2.

(23) FIG. 3 shows a system for energy storage and recovery according to the present invention with compressed-air and pressurized-water tanks arranged in groups. FIG. 3 shows, as an example, two groups each consisting of two compressed-air tanks and one pressurized-water tank.

(24) To avoid undue repetition, reference is made to the description of FIGS. 1 and 2. In the system shown in FIG. 3, unlike FIG. 2, two compressed-air tanks 1 are connected to one pressurized-water tank 2. The outlets 1a of the two compressed-air tanks 1 are connected to the inlet 2e of a pressurized-water tank 2 via a pressure line 5. Two compressed-air tanks 1 and one pressurized-water tank 1 thus form one group (storage group). It goes without saying that a plurality of compressed-air tanks, or a plurality of pressurized-water tanks, could also be connected to form a group. The figure does not show stop valves which are present between the inlet 2e of a pressurized-water tank 2 and an outlet 1a of a compressed-air tank 1 within one group.

(25) The pressurized-water tanks 2 of the groups are connected to the reaction turbine 3 at their outlets 2a (cf. explanations with respect to FIG. 1). Herein, the outlets 2a of the pressurized-water tanks are connected to each other via a pressure line 5, wherein the pressure line 5 has a gradient in the direction of the sump.

(26) In the systems as shown in FIGS. 2 and 3, the required water is filled into the pressurized-water tank 2 prior to the initial operation of the system. Advantageously, initial filling of the pressurized-water tank 2 is carried out after filling the compressed-air tank(s) with compressed air. The required pressure in the compressed-air tanks 1, or the pressurized-water tank 2, is generated with the aid of the compressor 17 and filled into the compressed-air tank(s) 1 from the compressed-air reservoir 18. Depending on the required operating pressure, the pressure in the compressed-air tank 1 and thus in the pressurized-water tank 2 is increased to 10, 50, 100, 200 or 1000 bar.

(27) The request for energy issued by the network computer of the power grid S causes the control and comparison unit 13 to open the stop valve 6 between the pressurized-water tank 2 and the turbines 3, 3a, thus causing the pressurized water in the pressurized-water tank 2 to be fed to the reaction turbine 3 and to the constant pressure turbine 3a coupled therewith. The amount of water flowing into the reaction turbine 3 is adjusted by the control and comparison unit 13. This is how the power generated by the reaction turbine 3 and the constant pressure turbine 3a is regulated. The generator 4 coupled to the reaction turbine 3 and the constant pressure turbine 3a generates the amount of energy requested by the network computer 15 of the power grid S and feeds it into the power grid S.

(28) In this way it is possible for the control and comparison unit 13 to control the energy recovery and energy storage in the system. The control and comparison unit 13 receives instructions with respect to each phase of operation from the network computer 15 of the power grid S via corresponding data lines 16, as to whether the system is in the energy recovery or energy storage operating phase.

(29) FIG. 4 shows a system for energy storage and recovery according to the present invention comprising a Pelton turbine and a frequency converter. FIG. 4 differs from the system described in FIG. 3 only in the arrangement of the turbine connected to the pressurized-water tank 2. In FIG. 4, a Pelton turbine 3a is connected to the pressurized-water tank 2. A generator 4 and a frequency converter 4a is connected to the drive shaft AW of the Pelton turbine 3a. The generator 4 is thus connected between the Pelton turbine 3a and the frequency converter 4a. The frequency converter 4a is connected to the public power grid S.

LIST OF REFERENCE NUMERALS

(30) 1 compressed-air tank 1e inlet 1a outlet 2 pressurized-water tank 2e inlet 2a outlet 3 reaction turbine 3a constant pressure turbine E3 inlet of reaction turbine A3 outlet of reaction turbine E3a inlet of constant pressure turbine A3a outlet of constant pressure turbine AW drive shaft 4 generator 4a frequency converter 5 pressure line/connection line 6 stop valve 7 water inlet guide vanes 7a water inlet guide vanes 8 check valve 9 water reservoir 10 antechamber 10a opening 11 high-pressure pump 12 connection line 13 control and comparison unit 15 network computer 16 data line 17 compressor 18 compressed-air reservoir 19 stop valve S power grid SN level sensor SD pressure sensor