WO2012025449A1

WO2012025449A1 - Flow dividing device for a condensation steam turbine having a plurality of outlets

Info

Publication number: WO2012025449A1
Application number: PCT/EP2011/064207
Authority: WO
Inventors: Benjamin Kumm; Norbert Sürken
Original assignee: Siemens Aktiengesellschaft
Priority date: 2010-08-27
Filing date: 2011-08-18
Publication date: 2012-03-01
Also published as: CN103080480A; EP2423450A1; CN103080480B; EP2609295B1; EP2609295A1

Abstract

The invention relates to a flow dividing device for a condensation steam turbine having a plurality of outlets comprising a flow divider (5) dividing the total steam flow within the waste steam housing (2) into two steam flows (30, 31), each flowing through an associated condenser (14, 15), a stagnation point detection device (18-20) for locating the stagnation point (29) formed upon dividing the total steam flow at the front edge of the flow divider (6), and a coolant dividing device (21, 22) by means of which the coolant infeed (23) to the condensers (14, 15) is controlled as a function of the location of the stagnation point (29) such that the stagnation point (29) is centered on the flow divider (5) while avoiding a flow disruption (32).

Description

description

Flow divider device for a condensing steam turbine with a plurality of outlets

The invention relates to a flow divider device for a condensing steam turbine having a plurality of outlets.

For example, one stage of a condensing steam turbine, consisting of a stationary stator and an impeller rotating about the machine axis, is designed as a Baumann stage in which an annular web is mounted, with which the blade channels are divided into an outer and an inner sub-channel. Here, the Dampfmas ^¬ senstrom is divided into the stage with the flow divider into two partial streams which are then guided over different paths through the expansion more blading to a condenser. The web is the guide vanes intersecting installed in the Leit ^¬ blade grid, wherein the web has a circumferential Vor ^¬ edge.

Conventionally, the web is rigid so that the Nei ^¬ supply of the leading edge to the machine axis of the condensing steam turbine ^¬ over time is always constant. In general, the condensing steam turbine is taken as the inclination angle of the angle of attack of Dampfströ ^¬ tion, with the steam flow in Auslegungsbe- operating state meets the front ^¬ edge of the ridge. However, if the operating state of the condensing steam turbine deviates from the design mode, the velocity components of the steam flow may change such that the angle of approach of the steam flow is no longer equal to the angle of incidence of the leading edge of the web. Any deviation of the angle of attack from the angle of attack in the design mode of operation results in a false flow of the web, which results in an increase of flow losses in the steam flow. This false flow of the web may, for example, lead, depending on the inside or outside side Fehlanströmung that form on the inside or the outside of the web a pressure side or a suction side ^¬ . There is a risk that the Strö ^¬ tion replaces, which in turn high flow losses of the steam flow are the result on the intake side. These flow losses is impressed ^¬ pregnant thermodynamic efficiency of the condensing steam turbine, so that the condensing steam turbine in operating states operable away from the design operating condition only at lower efficiencies.

The object of the invention is to provide a flow dividing device for a condensing steam turbine having a plurality of outlets, wherein the condensing steam turbine is operated with a high thermal efficiency in operating states other than the design operating condition of the condensation ^¬ steam turbine.

The flow divider for a multi-outlet condensing steam turbine of the present invention includes a flow divider dividing the total steam flow into two vapor streams each flowing through a condenser associated therewith, a stagnation point detecting means for locating the stagnation point formed at the flow divider leading edge when dividing the total steam flow, and a cooling medium dividing means the cooling medium supply to the capacitors is controlled in dependence on the localization of the stagnation point in such a way that the stagnation point is centrally located while avoiding flow separation at the stagnation point divider. If the stagnation point located centrally on Strö ^¬ mung divider, the flow divider leading edge is substantially flows around symmetrical, so that it is not established at the flow divider flow separation. If, on the other hand, the stagnation point on the flow divisor front edge changes its position to the outside or inside, the flow divider would be misdirected, as a result of which flow separation can occur at the flow divider. The location of the stagnation point on the flow divider front edge results from the current operating state of the condensate ^¬ onsdampfturbine and the ratio of Abströmdrücke the vapor streams. The Abströmdrücke are in turn given by the cooling medium supply to the capacitors. An increase in the cooling medium supply to the condenser causes an increase in the heat dissipation when condensing the respective

Steam flow and thus an increase in the condenser capacity, whereby the condensation pressure is lowered as the discharge pressure of this steam flow. In contrast, it increases

Counterpressure of the vapor stream, if by reducing the cooling medium supply to the condenser, the condensation temperature and thus the condensation pressure are increased. Thereby, in each of the capacitors by the corresponding cooling medium supply to each of the capacitors, the condensation temperature and thus the condensation pressure for each of the vapor streams can be adjusted. In accordance with the ratio of the discharge pressures of the vapor streams, the total vapor mass flow at the flow divider is divided into corresponding partial mass flows, which according to the invention are set such that the dew point settles centrally on the flow divider leading edge, whereby the flow separation is prevented at the flow ^divider . As a result of the inventive localization of the stagnation point at the flow divider leading edge with the stagnation point detection device, the quality of the flow divider flow is to be determined, whereby the outflow pressure ratio of the vapor streams with the corresponding coolant supply is dependent on the flow quality, ie the position of the stagnation point on the flow divider front edge the individual capacitors is controlled. As a result, it is achieved according to the invention that the location of the stagnation point at the flow divider leading edge is due to the localization and the matching cooling medium supply to the individual capacitors in the central one

Position can be maintained at the flow divider, so that at different operating conditions of the condensing steam turbine, the flow divider always while avoiding the Flow separation is flowed around with little loss. Thereby, the condensing steam turbine with the inventive Strö ^¬ mung dividing means has a high thermal efficiency, even in operating states which are away from an operating state Auslegungsbe-, is matched to the approximately aerodynamically effective contour of the flow divider.

The stagnation point detection device preferably has a differential pressure detection device with which the differential pressure in the area of the flow divider leading edge between the vapor streams on the flow divider can be measured and the differential pressure of the cooling medium distribution device is provided for controlling the cooling medium supply to the condensers. If the stagnation point is located centrally on the flow divider, then the flow around the flow divider is essentially symmetrical. As a result, in the region of the flow divider leading edge for the vapor streams at the flow divider, pressure levels which are essentially the same are obtained. If the stagnation point on the flow divider leading edge is displaced on one side, then, on the side of the flow divider which faces the stagnation point, there is generally a higher pressure level than on the other side of the flow divider facing away from this side. Thus, the differential pressure in the region of the flow divider leading edge between the vapor streams at the flow divider is a measure of the mean of the stagnation point.

The differential pressure detecting device preferably for each of the vapor streams has a pressure transducer for measuring the static pressure at the surface of the flow divider in the region of the flow divider leading edge and a Differenzdru ^¬ sugar mediation device with which the difference between the static pressures can be determined. Thereby providing the differential pressure detecting apparatus of the differential pressure on the two sides of the flow divider, so that with the Differenzdru ^¬ sugar averaging device, the cooling medium supply to the capacitors in response to the differential pressure, which is detected by the differential pressure detection apparatus, is controllable. At least one of the pressure sensor is preferably directly un ^¬ terhalb the surface location of the flow divider angeord ^¬ net at which the static pressure to the respective pressure sensor is measured. Alternatively or additionally, it is preferred that at least one of the pressure sensor from the surface location of the flow divider, to which the MES ^¬ send static pressure is applied, is remotely located and coupled to a pressure-transmitting channel in the flow divider with the surface location. The pressure-transmitting channel may be, for example, a pressure measuring bore. Alternatively, further preferably, instead of the pressure sensor and the differential pressure detection apparatus, a differential pressure measurement device be pre see ^¬ that determines at respective surface locations of the flow divider to be measured static pressure.

The flow divider is preferably provided as a concentric ring to the machine axis of the condensation steam turbine, which is fixed to at least one Axialleitschaufel the condensation steam turbine, wherein projecting axially upstream of the Axialleitschaufel- leading edge in the region of ^¬ flow leading edge, so that the surface locations of the flow divider, at to which the static pressures to be measured are applied upstream of the axial guide vane leading edge. As a result, secondary flow influences of the axial guide vanes, such as corner vortices and boundary layers, are located downstream of the surface locations of the flow divider, so that the static pressures to be measured at these surface locations are substantially unaffected by the secondary flow influences of the axial guide vanes. Thereby, the position of the stagnation point at the Strö ^¬ tion divider leading edge an accurate measure of the quality of the airflow around the flow divider is because the detection of the jam ^¬ point position by means of the to be measured at the surface locations of the static pressure not from the secondary flow effects of Axialleitschaufeln is impaired. Preferably, a predetermined cooling medium mass flow as the cooling medium supply to the capacitors is divided with the Kühlmediumaufteilungseinrichtung depending on the differential pressure. In this case, the predetermined cooling medium ^{mass flow} preferably corresponds to the maximum available cooling medium mass flow for the condensation steam turbine. As a result, the maximum available heat is always dissipated by the maximum available cooling medium mass flow for dissipating the heat of condensation of the Kon ^¬ capacitors, wherein the maximum available cooling medium mass flow is divided among the capacitors. Further, it is preferred that with the cooling ^¬ medium distribution device, the cooling medium supply to the capacitors are controlled such that the back pressures of the individual vapor streams are such that the stagnation point is located centrally on the flow divisor front edge. The cooling ^¬ medium dividing means is preferably ferenz pressure detecting means with the dif- fed back via the differential pressure that the back pressures of the individual steam streams are set such that the absolute, Renz pressure detecting means by the differential detected differential pressure is minimal. Characterized according to the invention is achieved that the position of the stagnation point of the flow divider ^¬ is always punched centrally angesie wherein the absolute, detected by the Differenzdruckerfas ^¬ sungseinrichtung minimum pressure is substantially zero.

In the following, a preferred embodiment of a flow divider device according to the invention will be explained with reference to the accompanying schematic drawings. Show it:

Figure 1 is a schematic diagram of a condensing steam turbine with the embodiment of the flow divider device, a detail cross-section of a leading edge of a flow divider of the embodiment ^¬ example, the flow divider and Figures 3 to 5 the detail cross-section of Figure 2 at

different flow conditions around the leading edge of the flow divider.

As is apparent from Figures 1 to 5, a Kon ^¬ densationsdampfturbine 1 to an exhaust steam housing 2 in which a turbine rotor 3 is arranged. Through the exhaust steam housing 2 flows during operation of the condensing steam turbine 1 a

Total vapor mass flow, which exits at an exhaust steam outlet 4 of the exhaust steam housing 2.

In the exhaust steam housing 2, a flow divider 5 is arranged as an annular web which is coaxially located around the turbine rotor 3, and divides the flow channel in the Ab ^¬ steam housing 2 into an inner region and an outer region. The flow divider 5 comprises a Strömungstei ^¬ lervorderkante 6, wherein a flow divider 7 with chord in the cross section of the flow divider 5 dot-dash line is Darge ^¬ represents. The inner area of the flow channel of the ex ^¬ steam housing 2 is delimited by a flow parts gutter page 8, whereas the outer region is delimited by a flow divider outside 9, wherein connecting to the Strömungstei ^¬ lervorderkante 6, both the flow parts of the channel side 8 and the flow divider outside 9 located.

The flow divider 5 is in the exhaust steam housing 2 of an inner vane 10 and held an outer vane 11, wherein the flow divider 5 teilerinnseite with its flow 8 is fixed to the inner vane 10 and is ^¬ ner flow divider outside 9 to the outer vane. 11 From the flow divider 5, the Dampfge ^¬ total mass flow is divided into an inner vapor stream and an outer vapor stream, wherein at the Abdampfaustritt 4 for the inner vapor stream an inner exhaust steam line 12 and the outer vapor stream an outer exhaust steam line 13 are provided. The inner vapor flow is controlled by the internal exhaust steam tion 12 to a first condenser 14 and the outer vapor stream is passed through the outer exhaust steam line 13 to a second condenser 15, wherein the inner vapor stream in the first condenser 14 and the outer vapor flow in the second condenser 15 is condensed. From the first condenser 14, the condensate condensed by the inner vapor flow is discharged in a first condensate line 16, whereas the condensate condensed by the outer vapor flow is removed by a second condensate line 17 from the second condenser 15.

In the area of the flow divider leading edge 6, an inner pressure sensor is installed, an external pressure transducer 19 to the flow divider 18 and outside 9 in the Strö ^¬ mung splitter 5 at the Strömungsteilerinnseite. 8 With the pressure transducers 18, 19, the static pressure at the flow divider inside 8 with the inner pressure transducer 18 and the static pressure at the flow divider outer side 9 with the outer pressure transducer 19 are measured when flowing around the flow divider 5 immediately downstream of the flow divider leading edge 6. Further, in the flow divider 5, a pressure difference measuring device 20 is provided, with which the difference between the static pressures, which are measured by the pressure transducers 18, 19, is determined. The pressure difference is fed in the form of a elekt ^¬ step signal with a differential pressure signal line 21 of a cooling water dividing means 22nd

With the cooling water splitting device 22, a division of a total cooling water supply is accomplished, which is supplied through a total cooling water supply line 23 of the cooling water splitting device 22. The Gesamtkühlwas ^¬ serzuführung is divided into a first cooling water supply and a second cooling water supply, wherein the first cooling water supply in a first cooling water supply line 24 to the first capacitor 14 and the second cooling water supply in a second cooling water supply line 25 to the second capacitor 15 is supplied. With the first Kühlwasserzu ^¬ leadership is in the first capacitor 14 of the first steam condensed condensate, whereas in the second condenser 15 with the second cooling water supply in the second cooling water supply line 25 of the second vapor stream is condensed to condensate. Of the capacitors 14, 15, the condensate is discharged in each case with a cooling water discharge line 26, 27.

The flow around the flow divider ^front edge 6 is illustrated in FIGS. 3 to 5 with streamlines 28, 30, 31. The inflow has a stagnation point stream line 28, which forms a stagnation point 29 at the flow divider leading edge 6. Is at the bottom of Figures 3 to 5, an internal power line 30 and shown above an external power line 31, wherein the inner current ^¬ line 30 31 represent the inner vapor stream and the external power line outside the vapor stream. In FIG. 3, the stagnation point 29 lies on the flow divider chord 7, so that the stagnation point 29 is located symmetrically on the flow divider leading edge 6. Thereby, the flow lines 30, 31 formed symmet ^¬ driven by the flow divider tendon 7 whereby the flow around the flow divider 5 by the vapor streams is sym ^¬ metric. The values of the values measured by the pressure transducers 18, 19, static pressures are therefore approximately the same size, so that detected with the differential pressure meter 20, the differential pressure as approximately zero, fed from the Druckdiffe ^¬ rence device 20 in the differential pressure signal line 21 a corresponding signal becomes.

In the embodiment shown in Figure 4 flow around the flow divider leading edge 6 of the stagnation point is located 29 to above the Strö ^¬ mung divider tendon 7, so that the flow around the flow divider leading edge 6 is asymmetrical. Thus, a separation region 32 is formed on the flow inside 8, associated with the flow losses and efficiency reduction of the steam turbine condensation. Similarly, shown in Figure 5 is a flow around the flow divider leading edge 6, in which the stagnation point 29 is arranged to offset below the flow divider string 7 so that a separation region is formed at the Strömungstei ^¬ leraußenseite 9 32nd In the flow conditions shown in FIG. 4, the value of the static pressure measured by the outer pressure transducer 19 is greater than the value of the static pressure measured by the inner pressure transducer 18, so that from the differential pressure gauge 20 to the cooling water treatment device 22 via the differential pressure signal line 21 a corresponding signal is fed. The same applies to the flow conditions in FIG. 5, the value of the static flow rate measured by the outer pressure transducer 19

Pressure is less than the value of the measured from the inner pressure transducer 18, static pressure. The signal in the differential pressure signal line 21 is therefore approximately zero in the flow conditions according to FIG. 3, for example positive in the flow conditions according to FIG. 4, if the differential pressure is defined as the difference between the pressure at the outer pressure transducer 19 and the inner pressure transducer 18 , Accordingly, the pressure difference is negative at the flow behaves ^¬ Nissen according to FIG. 5 Via the differential pressure signal line 21, the cooling water splitting device 22 is provided with the differential pressure signal, wherein the cooling water splitting device 22 is switched so that at the positive differential pressure signal the Kühlwasserzu ^¬ drove ^¬ reduced by the first cooling water supply line 24 to the first capacitor 14 and while maintaining the total cooling water supply through the entire cooling water supply line 23, the cooling water supply through the second cooling water supply pipe 25 to the second condenser 15 is increased. In this case, the flow conditions in the direction of the flow conditions, which are shown in Figure 3, so that the stagnation point 29 moves from the flow divider outer side 9 on the Strö ^¬ tion divider chord 7. As a result, the symmetrical flow conditions around the flow divider 5 shown in FIG. 3 are again achieved, as a result of which the detachment region 32 shown in FIG. 4 has disappeared.

The present in the flow conditions according to Figure 5 negative differential pressure signal in the differential pressure signal In the cooling water splitter 22, the total cooling water supply in the total cooling water supply line 23 is divided into corresponding cooling water feeds for the first cooling water feed line 24 for the first condenser 14 and for the second cooling water feed line 25 for the second condenser 15 such that the Cooling water supply for the first capacitor 14 increases and the cooling water supply for the second condenser 15 is lowered, so that the stagnation point 29 migrates from the flow divider Linninnseite 8 on the flow divider chord 7. In this case, the detachment region 32 shown in FIG. 5 dissolves and the flow is again homogeneous and uniform according to FIG.

As a result of the regulation stored in the cooling water splitting device 22, which is coupled to the instantaneous location of the stagnation point 22 via the differential pressure signal, the inhomogeneous flow conditions shown in FIGS. 4 and 5 lead back to the symmetrical flow conditions shown in FIG. In this case, the detachment regions 32 shown in FIGS. 4 and 5 are dissolved, whereby a reduction of flow losses in the vapor streams is achieved. Thus, holding the thermal efficiency of the condensing steam turbine 1 is achieved at a high level, even though the operating conditions of the condensing steam turbine vary and may differ from a design point of Kondensa ^¬ tion turbine with the stored in the cooling water dividing means 22 control logic.

Claims

claims

A flow divider device for a condensing steam turbine having a plurality of outlets,

with a flow divider (5) which divides the total steam flow into two vapor streams (30, 31), each of which flows through a condenser (14, 15) associated therewith,

a stagnation point detection device (18-20) for localizing the stagnation point (29) forming part of the total steam flow at the flow divider leading edge (6) and a cooling medium splitting device (21, 22) with which the cooling medium supply (23) to the condensers (14, 15) is controlled in dependence on the location of the stagnation point (29),

the stagnation point (29) is centered on the flow divider (5) while avoiding flow separation (32).

2. Flow divider device according to claim 1,

the stagnation point detection device (18-20) having a differential pressure detection device (20),

with which the differential pressure in the region of the flow divider leading edge (6) between the vapor streams (30, 31) on the flow divider (5) can be measured and the differential pressure of the cooling medium distribution device (21, 22) for controlling the

Cooling medium supply (24, 25) to the capacitors (14, 15) is provided.

3. flow divider device according to claim 2,

wherein the differential pressure detecting means (18-20) for each of the vapor streams (30, 31) each comprise a pressure transducer (18, 19) for measuring the static pressure at the surface of the flow divider (5) in the region of the flow divider leading edge (6) and a differential pressure detecting device (20 ) having,

with which the differential pressure between the static pressures can be determined.

4. flow divider device according to claim 3, wherein at least one of the pressure sensor (18, 19) is arranged directly below the surface location of the flow divider (5) at which the static pressure with the respec conditions pressure transducer (18, 19) is measurable.

5. flow divider device according to claim 3 or 4, wherein at least one of the pressure transducer (18, 19) from the surface location of the flow divider (5), at which the static pressure to be measured is located, arranged away and with a pressure-transmitting channel in the flow divider (5). is coupled to the surface site.

6. flow divider device according to one of claims 3 to 5,

wherein the flow divider (5) is provided as a concentric ring which is fixed to at least one Axialleitschaufel (10, 11) of the condensation steam turbine (1), wherein in the region of the flow divisor front edge (6) this axially upstream of the Axialleitschaufelvorderkante ^¬ , so the surface location of the flow divider (5) against which the static pressures to be measured are located upstream of the axial guide vane leading edge.

7. flow divider device according to one of claims 2 to 6,

wherein with the Kühlmediumaufteilungseirichtung (21, 22) in dependence on the differential pressure, a predetermined cooling medium mass flow (23) as the cooling medium supply (24, 25) z the capacitors (14, 15) is divided.

8. flow divider device according to claim 7,

wherein the predetermined cooling medium mass flow (23) corresponds to the maximum available cooling medium mass flow

9. flow divider device according to one of claims 2 to 8,

wherein with the Kühlmediumaufteilungseinrichtung (21, 22), the cooling medium supply (24, 25) to the capacitors (14, 15) are controlled such that the back pressures of the individual vapor streams (30, 31) are such that the stagnation point (29) at the Flow divider front edge (6) is located centrally.

10. flow divider device according to claim 9,

wherein the cooling medium dividing means (21, 22) is fed back to the differential pressure detecting means (20) via the differential pressure, that the back pressures of the individual vapor streams (30, 31) are set such that the ^absolute differential pressure detected by the differential ^pressure detecting means (20) is minimum is.