Overload introduction into a steam turbine

Abstract

An assembly with a steam turbine and an overload valve, wherein the overload valve is arranged opposite the fresh steam valve and a fresh steam flows partially through the flow channel and partially into an overload inflow region via the overload valve.

Claims

1. An assembly comprising: a steam turbine with a two-shell casing which comprises an outer casing and an inner casing arranged therein, and a connection guided through the outer casing, wherein the connection comprises a first connection opening and a second connection opening which are formed on the inner casing, further comprising a first valve for feeding steam into the inner casing, wherein the first valve is fluidically connected to the first connection opening, further comprising a second valve for discharging steam, wherein the second valve is fluidically connected to the second connection opening, wherein the steam turbine further has an overload inflow region which is fluidically connected to the second valve, wherein the steam turbine has a blading region which is configured for a flow direction, and the overload inflow region opens into the blading region at a location downstream of a blade stage in the flow direction, wherein the first and second connection openings are formed oppositely on the inner casing.

2. The assembly as claimed in claim 1, wherein the steam turbine is of two-flow configuration, formed by a first flow channel and a second flow channel.

3. The assembly as claimed in claim 2, wherein the first and second valves are arranged on the first flow channel.

4. A method for operating a steam turbine with a two-shell casing including an outer casing and an inner casing arranged therein in overload operation, the method comprising: operating the steam turbine such that steam flows into an inflow region of the steam turbine via a first valve and a first connection opening, and the steam then flows partially into a blading region and partially out of the steam turbine via a second valve in an overload line and from the overload line flows into an overload inflow region of the steam turbine via a second connection opening, wherein the blading region is configured for a flow direction, and the overload inflow region opens into the blading region at a location downstream of a blade stage in the flow direction, wherein the first and second connection openings are formed oppositely on the inner casing.

5. The method as claimed in claim 4, wherein the second valve is closed in normal operation.

6. The method as claimed in claim 4, wherein the first valve is arranged oppositely to the second valve.

7. The method as claimed in claim 4, wherein the steam turbine is formed with a first and a second flow channel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows an assembly with a steam turbine and an overload inflow region according to the prior art.

(2) FIG. 2 shows an assembly according to the invention with an overload device.

(3) FIG. 3 shows an assembly according to the invention of two-flow configuration.

(4) FIG. 4 shows a schematic side view.

DETAILED DESCRIPTION OF INVENTION

(5) FIG. 1 shows an assembly 1 according to the prior art. The assembly 1 comprises a steam turbine 2 with a two-shell casing (not shown) which comprises an outer casing 3 and an inner casing (not shown) arranged therein. Furthermore, the steam turbine 2 comprises a connection 4 guided through the outer casing 3. The steam turbine 2 comprises a rotatably mounted rotor and an inflow region 5 for a fresh steam. The inflow region 5 is fluidically connected to a fresh-steam line 9. In this fresh-steam line 9 there are arranged a quick-closing valve 7 and a control valve 8. Furthermore, the arrangement 1 comprises a branching 9. At this branching 9 there is arranged an overload line 10 which opens into an overload inflow region 11 in the steam turbine 2. In the overload line 10 there is arranged an overload valve 12 which is arranged in the actual structure below the steam turbine 2, which leads to disadvantages.

(6) In normal operation, a fresh steam flows via the fresh-steam line 6 and the quick-closing valve 7 and control valve 8 into the inflow region 5 of the steam turbine. The thermal energy of the steam is converted into mechanical energy of the rotor. The rotation of the rotor can finally be converted into electrical energy by means of a generator. In an overload operation, that is to say when the steam generator generates more steam flow than in normal operation, the overload valve 12 is open and some of the steam is caused to flow via the overload line into the overload inflow region 11. In normal operation, the overload valve 12 is closed. Opening the overload valve 12 makes it possible to increase the power of the steam turbine 2.

(7) FIG. 2 shows an assembly 1 according to the invention. The fresh-steam line 6 is fluidically connected to the inflow region 5 via the quick-closing valve 7 and control valve 8. The connection 4 is designed with a pair of connection openings 4a, 4b formed by a first connection opening 4a and a second connection opening 4b which are formed on the inner casing. Furthermore, the assembly 1 comprises a second valve 12, which can be designated as an overload valve and is designed for discharging steam. This takes place via a discharge line 13 and opens into an overload line 10 into the overload inflow region 11. Thus, in the case of this assembly 1 according to the invention, the inflowing steam in an overload situation is channeled via the fresh-steam line 6 into the quick-closing valve 7 and then into the control valve 8 and flows via the inflow region 5 partially into a flow duct and partially out of the steam turbine 2 again via the discharge line 13. The steam channeled out of the steam turbine 2 flows via the overload valve 12 and an overload line 10 into an overload region 11.

(8) FIG. 3 shows an extended embodiment of the assembly according to FIG. 2. In the assembly according to FIG. 3, an overload steam is likewise channeled via the overload line 10 into an overload inflow region 11. The difference between the assembly according to FIG. 3 and the embodiment according to FIG. 2 is that the steam turbine 2 is embodied as a two-flow steam turbine with a first flow channel 14 and a second flow channel 15. A fresh steam flows via the fresh-steam line 6 into the first flow channel 14 and from there from the steam turbine 2 to an intermediate superheater (not shown). Steam then flows via a medium-pressure steam line 16 and a medium-pressure quick-closing valve 17 and medium-pressure control valve 18 into a medium-pressure inflow region 19. Steam then flows in the second flow channel 15 through a flow duct out of the steam turbine 2. The thermal energy of the steam is here converted into mechanical energy of the rotor.

(9) FIG. 4 shows a schematic side view of the inflow. Essentially, the steam turbine 2 is formed symmetrically to a vertical axis of symmetry 31 which passes through an axis of rotation 30. A rotor (not shown in FIG. 4) is rotatably mounted in an rotationally symmetrical manner about the axis of rotation. With respect to the axis of symmetry 31, the second connection opening 4b and discharge line 13 are arranged mirror-symmetrically oppositely to the connection opening 4a. A second variant of how the second connection opening 4b can be arranged oppositely is illustrated in FIG. 4 by the dashed line 32. Here, the second connection opening 4b is arranged oppositely on an imaginary line 33 which passes through the connection opening 4a and axis of rotation 30. The second connection opening 4b also lies on the imaginary line 33 here.

(10) Although the invention has been described and illustrated in more detail by way of the preferred exemplary embodiment, the invention is not limited by the disclosed examples and other variations can be derived herefrom by a person skilled in the art without departing from the scope of protection of the invention.