Power plant with heat reservoir

Abstract

A power plant having a steam circuit which can be supplied, in the region of a heat recovery steam generator, with thermal energy for producing steam, the steam circuit has, in the region of the heat recovery steam generator, a high pressure part, a medium pressure part and a low pressure part. In addition, a heat reservoir which has a phase change material and which is not situated in the region of the heat recovery steam generator is included, wherein, in order to supply the heat reservoir with thermally processed water, a supply line which leads out from the high pressure part or the medium pressure part is included and a discharge line which leads into the medium pressure part, the low pressure part or a steam turbine is included for discharging thermally processed water from the heat reservoir.

Claims

1. A power plant comprising: a steam circuit which is supplied, in a region of a heat recovery steam generator, with thermal energy for producing steam, wherein the steam circuit comprises, in the region of the heat recovery steam generator, a high-pressure part, a medium-pressure part and a low-pressure part, a heat reservoir which has a phase change material, which is not arranged in the region of the heat recovery steam generator, wherein the phase change material is different than water, a supply line proceeding from the high-pressure part or the medium-pressure part for the supply of thermally treated water to the heat reservoir, and a discharge line for a discharge of thermally treated water from the heat reservoir, and the discharge line opens into the medium-pressure part, the low-pressure part or a steam turbine.

2. The power plant as claimed in claim 1, wherein the heat reservoir is designed as a pressure vessel in which the phase change material is arranged.

3. The power plant as claimed in claim 1, wherein the heat reservoir has a sparger, and the thermally treated water from the supply line can be distributed in the heat reservoir via the sparger.

4. The power plant as claimed in claim 1, wherein the heat reservoir has at least one pressure measuring device and/or one temperature measuring device.

5. The power plant as claimed in claim 1, further comprising: a flash tank is connected into the discharge line, and the flash tank permits a separation of vaporous and liquid water.

6. The power plant as claimed in claim 1, wherein the supply line proceeds from an economizer or from a steam drum of the medium-pressure part.

7. The power plant as claimed in claim 1, wherein the supply line proceeds from an economizer or from a superheater of the high-pressure part.

8. The power plant as claimed in claim 1, further comprising: a recirculation line which at one side is fluidically connected to the heat reservoir and at an other side opens into the medium-pressure part at a location at which liquid water is conducted.

9. The power plant as claimed in claim 1, further comprising: a recirculation line which at one side is fluidically connected to the heat reservoir and at an other side opens into a flash tank from which a steam line leads into the low-pressure part.

10. The power plant as claim 1, further comprising: a steam superheater is connected to the discharge line.

11. A method for operating a power plant as claimed in claim 1, the method comprising: feeding thermally treated water from the high-pressure part or the medium-pressure part to the heat reservoir for charging purposes; recirculating liquid water via the recirculation line to the medium-pressure part; interrupting the feed of the thermally treated water when a predetermined pressure or a predetermined temperature is attained in the heat reservoir; after the interruption, discharging the water stored in the heat reservoir to the medium-pressure part, the low-pressure part or the steam turbine via the discharge line.

12. The method for operating a power plant as claimed in claim 11, wherein the discharging of the stored water is performed following a demand for secondary frequency support, and the stored water is discharged to the medium-pressure part between a steam drum and the superheater of the medium-pressure part.

13. The method for operating a power plant as claimed in claim 11, wherein the discharge of the stored water is performed upon starting of the steam turbine, and the stored water is discharged directly to the steam turbine without firstly being conducted to the medium-pressure part or to the low-pressure part of the power plant.

14. The method for operating a power plant as claimed in claim 11, wherein the discharging of the stored water is performed when the steam turbine is in a standby state in which the steam turbine is not outputting any power.

15. The method for operating a power plant as claimed in claim 11, wherein the discharging of the stored water is performed when the steam turbine is under normal load, and the stored water is also discharged to the medium-pressure part for further increase of power.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the figures:

(2) FIG. 1 shows a schematic diagram view of a first embodiment of the power plant 1 according to the invention;

(3) FIG. 2 shows a second embodiment of the power plant 1 according to the invention in a schematic diagram view;

(4) FIG. 3 shows a further, third embodiment of the power plant 1 according to the invention in a schematic diagram view;

(5) FIG. 4 is an illustration, in the form of a flow diagram, of an embodiment of the method according to the invention for operating a power plant.

DETAILED DESCRIPTION OF INVENTION

(6) FIG. 1 shows a schematic diagram view of an embodiment of the power plant 1 according to the invention, in which water in a steam circuit 2 is thermally treated by means of a heat recovery steam generator 3 in order to subsequently convert its thermal energy into rotational mechanical energy by means of a steam turbine 3. The heat recovery steam generator 3 is in particular supplied with thermal energy by means of the exhaust gas of a gas turbine 8, wherein those regions of the steam circuit 2 which are arranged relatively close to the gas turbine in terms of flow are at a relatively high temperature. Within the heat recovery steam generator 3, the individual heat exchangers 3 may be assigned to different regions. The region which has the highest temperatures and pressures is the high-pressure part 11; the part which has the next highest pressures and temperatures is the medium-pressure part 12; and the third part, the low-pressure part 13, has the lowest pressures and temperatures. Both the high-pressure part 11 and the medium-pressure part 12 and the low-pressure part 13 may have an economizer, a heat exchanger with steam drum, and an intermediate superheater or superheater. The individual pressure parts 11, 12, 13 are, correspondingly to the pressure and temperature level, connected to individual turbines of the multi-part steam turbine 4. Thus, the high-pressure part 11 is connected to a high-pressure steam turbine 5, the medium-pressure part 12 is connected to a medium-pressure steam turbine 6, and the low-pressure part 13 is connected to a low-pressure steam turbine 7. The individual steam turbines 5, 6, 7 are each connected to one another by means of a shaft, wherein the gas turbine 8 may for example be connected via a clutch 9 to the steam turbine 4 via said shaft. Likewise mechanically connected to the shaft is a generator 10, such that, when the rotational movement is performed, electrical power can be made available.

(7) Furthermore, a heat reservoir 20 is included which has a phase change material 21 which is integrated into the heat reservoir 20. In particular, the phase change material 21 is in the form of individual pieces which are encapsulated, and which are for example present as a filling in the heat reservoir 20. For the thermal charging of the heat reservoir 20 together with the phase change material 21 situated therein, it is possible for firstly thermally treated water, for example in the form of steam, to be taken from the economizer 14 of the medium-pressure part 12 and supplied to the heat reservoir 20. For this purpose, the heat reservoir 20 is connected to the economizer 14 of the medium-pressure part 12 via a supply line 25, wherein the flow rate of thermally treated water taken from the medium-pressure part 12 can be adjusted by means of a supply line valve 28. During the charging process in the heat reservoir 20, condensation of the steam normally occurs, which precipitates for example as liquid water on the base of the heat reservoir 20. The condensed water, which may nevertheless still have a high thermal heat content, can be recirculated via a recirculation line 24 from the heat reservoir 20 into the steam drum 15 of the medium-pressure part 12 again. There, the recirculated water can be supplied for thermal treatment in the heat recovery steam generator 3 again. The loss of water from the steam circuit 2 can consequently be avoided.

(8) When the heat reservoir 20 has been approximately fully charged, that is to say when the volume of the heat reservoir 20 has been approximately filled with steam, wherein the phase change material 21 is likewise present in fully charged form, the steam can be taken from the heat reservoir 20 again for example for the increase of power during operation of the power plant 1. Here, the steam is supplied, for example via a discharge line 26, to the medium-pressure part 12 in the region between the steam drum 15 and the superheater 16 of the medium-pressure part 12. The amount of supplied steam can in turn be adjusted by means of a discharge line valve 27 in the discharge line 26.

(9) If, for example in the case of peak load operation, an increased output of electrical energy is required, the amount of steam additionally supplied to the medium-pressure part 12 can permit increased power operation of the steam turbine 4, whereby an increased amount of electrical power can be output by the generator 10.

(10) FIG. 2 shows a further embodiment of the power plant 1 according to the invention in a schematic diagram view. Here, the basic construction of the steam circuit 2 of the power plant 1 is identical to the embodiment as per FIG. 1. Only the connection of the heat reservoir 20 differs insofar as the supply line is connected not to the medium-pressure part 12 but to the high-pressure part 11. Here, the connection is present directly upstream of the superheater 17 of the high-pressure part 11. As a result, the heat reservoir 20 can be charged with steam at a considerably higher temperature level and pressure level. This in turn results in a greater energy content in the heat reservoir 20, such that, during discharging via the discharge line 26 into the medium-pressure part 12, a relatively greater amount of energy can be discharged for the increase of power of the steam turbine 4.

(11) FIG. 3 shows a further embodiment of the power plant 1 according to the invention, whose basic construction of the steam circuit 2 in turn is substantially identical to the preceding embodiments. By contrast, the heat reservoir 20 is designed as a steam pressure reservoir in which there is arranged a sparger 32 via which the steam supplied via the supply line 25 from the high-pressure part 11 can be distributed in a relatively uniform manner. The steam required for the charging of the heat reservoir 20 is in this case taken from the superheater 17 of the high-pressure part 11.

(12) After high-pressure steam is taken from the steam circuit 2 and conducted into the heat reservoir 20, condensation of some fractions of the steam typically occurs, wherein this can be conducted via the recirculation line 24 to the low-pressure part 13. For the separation of the vaporous fractions and the liquid fractions before supply to the low-pressure part 13, the power plant 1 also has a flash tank 30, which is likewise connected into the return line 24. A steam line 31 leads away from the flash tank 30, which steam line is connected to the steam drum of the low-pressure part 13. At the same time, the liquid condensate in the flash tank 30 can likewise be supplied to the steam drum of the low-pressure part 13, but in a region in which the liquid phase of the water has accumulated.

(13) For the further thermal charging of the heat reservoir, a water supply line 33 is also provided, which can discharge thermally treated water from the economizer of the medium-pressure part 12. The amount of water conducted here is adjusted by means of a water supply line valve 34 in the water supply line 33.

(14) When thermal energy is taken from the heat reservoir 20, steam that has accumulated in the heat reservoir 20 is supplied via a flash valve, not denoted in any more detail with a reference designation, to a steam superheater 40, which is designed for example as a reservoir box. The steam emerging from said steam superheater 40 is subsequently conducted to the medium-pressure steam turbine 6 of the steam turbine 4. To supply yet further thermal energy to the steam taken from the steam superheater 40, the steam circuit has a bypass line 35 which mixes the steam discharged from the steam superheater 40 with steam from the superheater 17 of the high-pressure part 11. The steam superheater 40 is advantageously likewise designed as a heat reservoir with phase change material, wherein the thermal charging of said steam superheater 40 takes place substantially similarly to the charging of the heat reservoir 20. The required line portions or method steps are not described in any more detail in the present application but are evident to a person skilled in the art.

(15) FIG. 4 shows an embodiment of the method according to the invention for operating a power plant as described above, which method comprises the following steps: feeding thermally treated water from the high-pressure part (11) or the medium-pressure part (12) to the heat reservoir (20) for charging purposes (first method step 101); recirculating liquid water via the recirculation line (24) to the medium-pressure part (12) (second method step 102); interrupting the feed of thermally treated water when a predetermined pressure or a predetermined temperature is attained in the heat reservoir (20) (third method step 103); after the interruption, discharging the stored water in the heat reservoir to the medium-pressure part (12), the low-pressure part (13) or the steam turbine (4) via the discharge line (26) (fourth method step 104).

(16) Further embodiments will emerge from the subclaims.