Draining a power plant

Abstract

A power plant, particularly a coupled gas and steam power plant, including a plurality of first drainage lines that are fluidically connected on the upstream side to a water-steam circuit and are fluidically connected on the downstream side to an overpressure vessel, is provided. Additionally, at least one steam-conducting supply line, via which steam can be fed back to the water-steam circuit, is fluidically connected to the overpressure vessel. A method for operating such a power plant, wherein the at least one steam-conducting supply line can supply steam to the water-steam circuit in the region of a low-pressure stage, particularly in the region of the steam drum of the low-pressure stage is also provided.

Claims

1. A coupled gas and steam power plant, comprising: a plurality of first drainage lines that are fluidically connected on an upstream side to a water-steam cycle that has a plurality of pressure stages, and which are fluidically connected on a downstream side to an overpressure vessel, wherein at least one steam-conducting line is also fluidically connected to the overpressure vessel via which steam is fed again into the water-steam cycle; wherein the at least one steam-conducting feed line feeds steam to the water-steam cycle in a region of a steam drum of a low-pressure stage.

2. The coupled gas and steam power plant as claimed in claim 1, wherein the plurality of first drainage lines are connected on the upstream side to the water-steam cycle in a region of a high-pressure stage and/or an intermediate pressure stage.

3. The coupled gas and steam power plant as claimed in claim 1, wherein the plurality of first drainage lines are connected on the upstream side to the water-steam cycle in a region of the low-pressure stage.

4. The coupled gas and steam power plant as claimed in claim 1, further comprising an atmospheric pressure vessel that enables a steam expansion to essentially atmospheric pressure, and which is connected in respect to piping to the overpressure vessel so that steam is directed from the overpressure vessel into the atmospheric pressure vessel.

5. The coupled gas and steam power plant as claimed in claim 4, wherein a control means is also included in the coupled gas and steam power plant and is designed for adjusting a quantity of steam which is directed from the overpressure vessel into the atmospheric pressure vessel.

6. The coupled gas and steam power plant as claimed in claim 4, wherein inclusion is made for a plurality of second drainage lines which are connected on the upstream side to the water-steam cycle, and which are connected on the downstream side to the atmospheric pressure vessel, and via which water and/or steam is fed from the water-steam cycle to the atmospheric pressure vessel.

7. The coupled gas and steam power plant as claimed in claim 6, wherein the plurality of second drainage lines are connected on the upstream side to the water-steam cycle in the region of the low-pressure stage.

8. The coupled gas and steam power plant as claimed in claim 1, wherein the atmospheric pressure vessel is connected to a recirculation line that enables water to be fed from the atmospheric pressure vessel to a first refrigeration source, and the thereby thermally treated water to be fed back into the atmospheric pressure vessel again.

9. The coupled gas and steam power plant as claimed in claim 4, wherein the overpressure vessel and/or the atmospheric pressure vessel are, or is, connected in respect to piping to a second refrigeration source that enables water which is discharged from the overpressure vessel and/or from the atmospheric pressure vessel to be thermally treated.

10. The coupled gas and steam power plant as claimed in claim 1, wherein the overpressure vessel and/or the atmospheric pressure vessel are, or is, connected in respect to piping to a collecting vessel into which water which is correspondingly present in the overpressure vessel and/or in the atmospheric pressure vessel is transferred for storage.

11. The coupled gas and steam power plant as claimed in claim 10, wherein the collecting vessel is connected in respect to piping to a treatment unit, wherein the treatment unit at least partially clears the water of impurities.

12. The coupled gas and steam power plant as claimed in claim 10, wherein the collecting vessel and/or the treatment unit are, or is, connected in respect to piping to a main condenser of the coupled gas and steam power plant in such a way that water is fed from this to the main condenser.

13. A method for operating a power plant as claimed in claim 1, comprising the following steps: draining water and/or steam from the water-steam cycle by feeding to the overpressure vessel; and feeding back steam from the overpressure vessel to the water-steam cycle in the region of the steam drum of the low-pressure stage.

Description

BRIEF DESCRIPTION

(1) Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:

(2) FIG. 1 shows a schematic representation of an embodiment of the power plant; and

(3) FIG. 2 shows a flow-diagrammatic representation of an embodiment of the method for operating a power plant.

DETAILED DESCRIPTION

(4) FIG. 1 shows a possible embodiment of the present power plant 1 according to embodiments of the invention which has a water-steam cycle 2. According to the embodiment, the water-steam cycle 2 is included in the steam section of a gas and steam power plant 1. In this case, the water-steam cycle 2 has in all three different pressure stages 3, 5, 7 which serve for steam preparation. The steam which is prepared in these pressure stages 3, 5, 7 is fed, for power generation, to a steam turbine 90 (or to a plurality of steam turbines 90) which is, or are, fluidically connected to a main condenser 100 as a refrigerating source. It is also possible to conduct the steam which is prepared in the pressure stages 3, 5, 7, via bypass stations which are not additionally provided with designations, to the main condenser 100 for condensing.

(5) In order to feed the drainage waters in the respective pressure stages 3, 5, 7—which accumulate during a start-up or shutdown operation or during normal operation or in the stationary mode of the power plant 1—to a purification plant or to a feedback line according to embodiments of the invention into the water-steam cycle 2, the power plant 1 provides a number of first drainage lines 11 which allow the drainage waters which are extracted from the pressure stages 3, 5, 7 to be fed to an overpressure vessel 20. In this case, the first drainage lines 11 are fluidically connected on the upstream side to corresponding line sections of the respective pressure stages 3, 5, 7. The first drainage lines 11 are especially fluidically connected on the upstream side to the steam drum 4 of the high-pressure stage 3 or to the steam drum 6 of the intermediate pressure stage 5. To this end, the first drainage lines 11 could alternatively be fluidically connected on the upstream side to a flange—not additionally shown—of a forced circulation steam generator of the high-pressure stage 3 or connected to a flange—not additionally shown—of a forced circulation steam generator of the intermediate pressure stage 5. A possible connection to the steam drum 8 of the low-pressure stage 7 also exists but which can also be dispensed with according to the embodiment. According to another advantageous embodiment, this last-named first drainage line 11 is not provided for discharging drainage waters from the low-pressure stage 7 into the overpressure vessel 20.

(6) After introduction of the drainage waters into the overpressure vessel 20, a separation into vaporous and liquid proportions of the drainage waters is carried out, wherein the vaporous proportions can advantageously be fed back into the water-steam cycle 2 again. Since the steam does not exist in impure form, treated water/steam can therefore easily be made available to the water-steam cycle without further purification. To this end, a feed line 12 is fluidically connected to the overpressure vessel 20 and on the downstream side is connected to the steam drum 8 of the low-pressure stage 7. Therefore, it is possible to feed the steam which is present in the overpressure vessel 20 to the low-pressure stage 7 which is operated at a lower pressure level in comparison to the high-pressure stage 3 or the intermediate pressure stage 5, wherein the thereby fed back steam can be made available again for electric power generation by means of the turbine 90 (steam turbine). The turbine 90 can in this case also be designed as a number of individual turbines which are suitably connected to the respective pressure stages 3, 5, 7.

(7) The power plant 1 furthermore comprises an atmospheric pressure vessel 30 which is also fluidically connected to the overpressure vessel 20. In the line which is provided for connecting purposes between the overpressure vessel 20 and the atmospheric pressure vessel 30 provision is also made for a control means 25 which allows the fluid connection to be interrupted or the fluid flow to be suitably adjusted. Therefore it is possible to transfer the steam which is present in the overpressure vessel 20 during operation to the atmospheric pressure vessel 30. As a result, on the one hand the pressure level in the overpressure vessel 20 can be suitably adjusted, and on the other hand the drainage waters which accumulate in the atmospheric pressure vessel 30 can be suitably discharged without the pressure level in the overpressure vessel 20 having to be altered at the same time. Therefore, according to the embodiment provision is made for a discharge line 35 via which especially water in vaporous form can be fed from the atmospheric pressure vessel 30 to the surroundings/environment U.

(8) For draining the low-pressure stage 7, which operates at a comparatively lower pressure level, provision is made, moreover, for second drainage lines 13 which enable a transfer of the drainage waters which accumulate in the low-pressure stage 7 into the atmospheric pressure vessel 30.

(9) In order to treat the drainage waters, especially in liquid form, which have accumulated in the overpressure vessel 20 as well as in the atmospheric pressure vessel 30, for further use in the water-steam cycle 2, they can be drained into a collecting vessel 70. For thermal conditioning, especially for cooling these drainage waters before introduction into the collecting vessel 70, provision is made according to embodiments of the invention for a first refrigeration source 50 as well for a second refrigeration source 60.

(10) In addition, the power plant 1 provides a recirculation line 40 which allows drainage waters to be extracted from the atmospheric pressure vessel 30 in order to feed it to the first refrigeration source 50. After this, the thereby thermally conditioned drainage waters are completely or partially fed again to the atmospheric pressure vessel 30, but at a lower temperature level. This temperature treatment allows the reduction of an undesirable vapor formation in the atmospheric pressure vessel 30 since the steam is condensed.

(11) FIG. 2 shows a flow-diagrammatic representation of an embodiment of the method according to embodiments of the invention for operating a power plant. In this case, the following steps are included:

(12) draining water and/or steam from a water-steam cycle 2 by feeding to an overpressure vessel 20 (first method step 200);

(13) feeding back steam from the overpressure vessel 20 to the water-steam cycle 2 in the region of a low-pressure stage 7, especially in the region of a steam drum 8 of the low-pressure stage 7 (second method step 210).

(14) Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.

(15) For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements. The mention of a “unit” or a “module” does not preclude the use of more than one unit or module.