METHOD FOR OPERATING A TURBINE UNIT, STEAM POWER PLANT OR COMBINED-CYCLE POWER PLANT, AND USE OF A THROTTLING DEVICE

Abstract

A method for operating a turbine unit having at least two partial turbines, wherein a steam volumetric flow is conducted by a steam transfer device from the partial turbine arranged upstream to a partial turbine arranged downstream, which is connected after the partial turbine arranged upstream, wherein a pressure level within the steam transfer device is manipulated in accordance with a load range in which the turbine unit is operated, in such a way that the exhaust steam of the partial turbine arranged upstream remains superheated in the event of operation of the turbine unit in a partial-load range below the IGV point and/or in the event of a quick increase in the partial load.

Claims

1. A method for operating a turbine unit comprising at least two part-turbines, the method comprising: guiding a steam volume flow by a steam crossover device from the part-turbine arranged upstream to a part-turbine arranged downstream and connected downstream from said part-turbine arranged upstream, manipulating a pressure level inside the steam crossover device, depending on a load range at which the turbine unit is running, in such a way that the exhaust steam of the part-turbine arranged upstream remains superheated in the event of the turbine unit being operated in a part load range below the IGV point and/or in the event of rapid increase in the part load.

2. The method as claimed in claim 1, wherein the pressure level inside the steam crossover device is manipulated in such a way that premature expansion of the exhaust steam coming from the part-turbine arranged upstream into the wet steam region is prevented.

3. The method as claimed in claim 1, wherein, depending on a load range at which the turbine unit is running, the steam volume flow in a steam crossover device is throttled in order to prevent the critical development of wet steam.

4. The method as claimed in claim 1, wherein the pressure level is manipulated by a control element arranged inside the steam crossover device.

5. A steam power plant or a combined-cycle power plant comprising: a turbine unit comprising at least two part-turbines which are operatively connected to each other by a common steam crossover device, and a controller or regulator for controlling and/or regulating a pressure level and/or steam volume flow inside the common steam crossover device in order to influence wet steam behavior.

6. The steam power plant or a combined-cycle power plant as claimed in claim 5, further comprising: means for preventing a critical development of wet steam inside the common steam crossover device, and wherein the means for preventing the critical development of wet steam are arranged at least partially inside the common steam crossover device.

7. The steam power plant or combined-cycle power plant as claimed in claim 6, wherein the controller or regulator for controlling and/or regulating a pressure level or a steam volume flow, or means for preventing a critical development of wet steam activates depending on a load range operated by the turbine unit.

8. The steam power plant or combined-cycle power plant as claimed in claim 6, further comprising: means for cooling or heating a waste heat boiler of the turbine unit, wherein the waste heat boiler is cooled or heated depending on a load range operated by the turbine unit.

9. The steam power plant or combined-cycle power plant as claimed in claim 8, further comprising: a processing device which activates and operates in a coordinated manner the controller or regulator for controlling and/or regulating a pressure level or a steam volume flow, and/or the means for preventing the critical development of wet steam, and/or the means for cooling or heating a waste heat boiler of the turbine unit.

10. The steam power plant or combined-cycle power plant as claimed in claim 6, wherein the controller or regulator for controlling and/or regulating a pressure level or a steam volume flow or the means for preventing the critical development of wet steam have a throttle flap part or a throttle valve part of a throttling device.

11. A method for preventing or at least curbing the critical development of wet steam, comprising: using a throttling device, wherein the throttling device is provided at a steam crossover device arranged between two part-turbines.

12. The steam power plant or a combined-cycle power plant as claimed in claim 6, adapted to implement a method for operating a turbine unit, wherein the method comprises: guiding a steam volume flow by the steam crossover device from a part-turbine arranged upstream to a part-turbine arranged downstream and connected downstream from said part-turbine arranged upstream, manipulating a pressure level inside the steam crossover device, depending on a load range at which the turbine unit is running, in such a way that the exhaust steam of the part-turbine arranged upstream remains superheated in the event of the turbine unit being operated in a part load range below the IGV point and/or in the event of rapid increase in the part load.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In the drawing:

[0053] FIG. 1 shows schematically a part view of a turbine unit, provided at a combined-cycle power plant, with two part-turbines operatively connected to each other by means of a steam crossover device, wherein a pressure level inside the steam crossover device is manipulated depending on a load range at which the turbine unit is running in such a way that the exhaust steam of the part-turbine arranged upstream remains superheated in the event of operation of the turbine unit in a part load range below the IGV point and/or in the event of a rapid increase in the part load; and

[0054] FIG. 2 shows schematically an h-s diagram of the combined-cycle power plant shown in FIG. 1.

DETAILED DESCRIPTION OF INVENTION

[0055] The combined-cycle power plant 1 shown in FIG. 1 has a turbine unit 2, only two part-turbines 3 and 4 of which are shown according to the view in FIG. 1.

[0056] These two part-turbines 3 and 4 are operatively connected to each other by means of a common steam crossover device 5 in such a way that exhaust steam 6 coming from the part-turbine 3 arranged upstream is guided as a steam volume flow 7 to the part-turbine 4 arranged further downstream so that the latter is operated by means of the exhaust steam 6 of the part-turbine 3 arranged upstream.

[0057] In this exemplary embodiment shown specifically in FIG. 1, the first part-turbine 3, i.e. the part-turbine 3 arranged upstream, is a medium-pressure steam turbine 8 and the second part-turbine 4, i.e. the part-turbine 4 arranged further downstream, is a low-pressure steam turbine 9.

[0058] According to the invention, the combined-cycle power plant 1 is characterized by a turbine unit 2 which has control and/or regulating means 10 for controlling and/or regulating a pressure level and/or a steam volume flow 7 inside the steam crossover device 5 in order to influence wet steam behavior, wherein these control and/or regulating means 10 in this exemplary embodiment comprise, in a structurally simple fashion, a throttling device 11 provided at the common steam crossover device 5, the throttle flap part 12 of which is arranged inside the common steam crossover device 5.

[0059] By means of this simply constructed control and/or regulating means 10 it is possible to obtain, as required, an increase in pressure with respect to the exhaust steam 6 at the present turbine unit 2 or at the combined-cycle power plant 1, in particular if the turbine unit 2 is operated in lower part load ranges below the IGV point, as a result of which it is constantly ensured that this exhaust steam 6 always remains superheated for as long as possible.

[0060] The same also applies in the event of a rapid increase in the part load, in particular from such lower part load ranges, wherein a waste heat boiler (not shown in detail here) can hereby be cooled by means (not shown further here) for cooling or heating the waste heat boiler of the turbine unit 2 in order to reduce the temperature at the part-turbine 4 connected and arranged downstream.

[0061] In this respect, this throttling device 11, with its throttle flap part 12 arranged in the common steam crossover device 5, also incorporates means 15 for preventing the development of wet steam inside the common steam crossover device 5 in order to achieve the above-described effects.

[0062] The throttling device 11 and its throttle flap part 12 are hereby arranged in an outlet support part 16 of the common steam crossover device 5 so that in particular the throttle flap part 12 is placed directly behind an exhaust steam outlet 17 of the part-turbine 3 arranged upstream.

[0063] In the present case, the throttle flap part 12 thus already incorporates a control element 18 by means of which the pressure level inside the common steam crossover device 5 can be manipulated within the sense of the present invention.

[0064] In order to be able to mutually employ the control and/or regulating means 10 and the means 15 for preventing the development of wet steam, and the means for cooling or heating the waste heat boiler of the turbine unit 2 in a coordinated manner, the turbine unit 2 also has a correspondingly designed processing device 20 which is designed such that the turbine unit 2 described here can be operated within the sense of the invention. This processing device 20 can hereby take the form of both hardware and software.

[0065] In the h-s diagram 25 shown in FIG. 2 for the turbine unit 2 shown at least partially in FIG. 1 of the combined-cycle power plant 1, the entropy values are plotted on the x-axis 26 and the enthalpy values on the y-axis 27, wherein the saturation curve 28 is clearly illustrated.

[0066] Also visible in this h-s diagram 25 is a usual expansion curve 29 with respect to expansion behavior of the exhaust steam 6 inside the common steam crossover device 5 without the use of the present control and/or regulating means 10 and the means 15 for preventing the development of wet steam in the event of operation of the turbine unit 2 in low part load operation below the IGV point of the turbine unit 2.

[0067] Drawn above this usual expansion curve 19 by way of example is a new expansion curve 30 of expansion behavior of the exhaust steam 6 inside the common steam crossover device 5 with the assistance of the present control and/or regulating means 10 and the means 15 for preventing the development of wet steam in the event of operation of the turbine unit 2 in low part load operation below the IGV point of the turbine unit 2.

[0068] It can be clearly seen that the turbine unit 2 can be operated outside the wet steam region 31 for much longer using the method proposed according to the invention. In other words, this means that the development of wet steam takes place at a location where it is desired, namely in the region of a low-pressure part.

[0069] Whilst the usual expansion curve 29 according to the view in FIG. 2 at the point 32 runs further toward the wet steam region 31, as a result of the use of the present control and/or regulating means 10 and the means 15 for preventing the development of wet steam at least temporarily, the new expansion curve 30 successfully runs from this point 32 for a stretch 33 in the sense of an isothermic change of state for a period essentially along an isotherm 34, as a result of which the exhaust steam 6 can expand for longer above the saturation curve 28 before the new expansion curve 30 runs again similarly to the usual expansion curve 29 in its continuation.

[0070] It should be explicitly pointed out at this point that the features of the solutions described above and in the claims can optionally also be combined in order to be able to realize or achieve the described features, effects, and advantages in a correspondingly cumulative manner.

[0071] Although the invention has been illustrated and described in detail in the preferred exemplary embodiment, the invention is not limited by this disclosed exemplary embodiment and other variants can be derived by a person skilled in the art without going beyond the scope of the invention.