CN103925012B - There is the turbo machine of initiatively electric gap control - Google Patents

Abstract

The present invention relates to turbomachines with active clearance control. The present disclosure relates to a turbomachine (10) comprising a stator (22, 23, 45, 49) and a rotor (28) arranged to rotate within said stator (22, 23, 45, 49) and at least one Electric heating means (40, 41, 42, 43, 46) arranged on at least a part of the surface of the stator (22, 23, 45, 49) for active gap control. In addition to a turbine, a method for operating active gap control including an electric heating device is also disclosed.

Description

Turbine with Active Clearance Control

technical field

The present invention relates to a turbomachine with active clearance control, and to a method of operating such a machine with active clearance control. Clearance control allows reducing the clearances of the turbomachine, primarily the clearances between the rotating blades and the casing, and the clearances between the vanes and the rotor.

Background technique

In a turbomachine, radial and axial clearances are the result of relative movement of rotating components (rotor, rotor blades) and stationary components (stator, stator vanes). Typically, no active gap control is used, instead all parts expand or contract passively as a function of mechanical and thermal boundary conditions.

Careful design of components minimizes clearances by finding a good thermal match between rotor and stator. Thermally matched means that the components react to thermal transients at the same speed, ie they expand and contract at the same speed, and thus maintain the same gap. This is called passive gap control. However, the design can only be optimized for certain transient operating modes and ranges, and is not used for the entire operating range (e.g., standstill, part load, base load) and transient operating modes (e.g., start-up, loading, unloading, and shutdown).

In some engines cold and hot air is blown to the stator components to heat them or cool them depending on the operating conditions, as is known for example from US7329953.

Contents of the invention

An aspect of the present disclosure is to provide a turbomachine comprising a stator and a rotor arranged to rotate within the stator and at least one electrical heating device arranged on a surface of at least one stator portion for active gap control . In this context, the stator includes all non-rotating components of the turbomachine, in particular the casing, which generally includes an inner casing, an outer casing and connecting walls, as well as supports for the casing and bearing supports for the bearings, which hold rotor.

Active clearance control allows reducing the clearances of the turbine, mainly the clearances between the rotating blades and the casing, and the clearances between the vanes and the rotor. The clearance can be reduced by active clearance control in order to increase the efficiency and power of the turbine.

According to one embodiment, the electric heating means are arranged in the cavity of the stator part to heat the fluid which at least partly surrounds the stator part and/or wherein the electric heating means are arranged on the stator part with direct mechanical contact to allow heating from the electric Conductive heat transfer from the device to the stator section. Suitable chambers in which heating means may be arranged are eg compressor bleed plenums or cooling air distribution plenums.

According to another embodiment, the electric heating device is arranged in the cooling air supply opening. For example, it can be arranged on the surface of the cooling air supply opening of the stator.

In another embodiment, the part of the stator on which the electric heating means is arranged is the inner and/or outer casing of the turbine.

In addition or as an alternative, the electric heating device is arranged on a connecting wall which connects the inner shell to the outer shell.

In yet another embodiment, the electrical heating means includes an induction heating element. In general, induction heating elements may be arranged on the surface of the respective stator part in order to introduce an alternating electromagnetic field into the stator part and thereby inductively heat the stator part. For induction heating, electromagnets may be arranged on or above the surface of the stator part. The stator part can then be heated by the electromagnet by introducing eddy currents into the stator part.

According to one embodiment, a plurality of electric heating devices are arranged distributed around the casing of the turbomachine in the axial direction and in the circumferential direction. The different electric heating devices are constructed and connected to the power supply such that the different electric heating devices can be independently controlled to control the heating intensity in the circumferential and axial directions of the turbine. In order to allow independent control of the heating intensity, the different electric heating means can eg be connected independently to the power supply.

According to one embodiment the turbine is a gas turbine and according to another embodiment the turbine is a steam turbine.

In addition to a turbine comprising an electric heating device for a stator part, a method of actively controlling the clearance of a turbine using an electric heating device is also an object of the present disclosure.

According to one embodiment of the method for operating a turbine comprising a stator and a rotor arranged to rotate within the stator and at least one electric heating device arranged on the surface of at least one stator part, the at least one electric heating device is controlled to heat At least one stator section for controlling the rotor-to-stator clearance.

According to another embodiment of the method, at least one heating element is arranged at the location of the upper or lower half of the housing. The heating element is controlled to heat the region of the housing where the heating element is arranged to reduce the circumferential temperature inhomogeneity of the housing. For example, if temperature measurements indicate that a zone in the upper half of the housing has a lower temperature than a corresponding zone in the lower half (e.g., at the same axial location), then the zone in the upper half of the housing The heating element in can be activated to heat the zone until it has the same temperature as the corresponding zone in the lower half.

For example, inhomogeneities in temperature may be caused by cooling air supply lines, which enter the housing on one side, or which are not equally distributed around the housing. Inhomogeneities in temperature can also be caused, for example, by damaged insulation leading to higher heat loss from the housing on one side.

In another embodiment, the at least one electric heating device is controlled to maintain the temperature profile of the casing of the turbine in the axial direction within a predetermined range. Depending on the load and operating conditions (steady state or transient), a certain temperature profile is expected in the axial direction of the gas turbine. If the measured temperature profile of the enclosure is outside the expected profile, the enclosure may be locally heated to establish the expected temperature profile.

According to one embodiment of the method, at least one heating element is arranged at the location of the lower half of the housing and it is used to heat the lower half of the housing during shutdown and cooling of the turbine. It heats the lower half of the housing to compensate for the increase in temperature of the upper half relative to the lower half due to convective heat transfer from the bottom to the top. By heating the lower half, the so-called deflection due to the higher temperature in the upper half can be mitigated.

According to yet another embodiment, at least one heating element is arranged to heat the flange connecting the lower and upper housing halves to reduce or avoid ovalization of the housings. The flange is generally at least partially kept cooler than the circular portion of the housing. It stays cooler because of the additional heat loss caused by the flange surface, and especially during loading of the turbine (ie heating of the turbine) because the additional flange material takes more time to heat up.

In another embodiment, at least one heating element is arranged on a bearing support of the turbomachine. At least one electric heating device arranged on the bearing support serves to heat the bearing support. The heating is controlled such that the rotor remains centered relative to the housing.

Typically, the bearing support is thermally insulated. Therefore, its thermal expansion is at least partially decoupled from the thermal expansion of the housing. If the housing expands differently than the bearing supports, this can lead to misalignment of the rotor and thus increase the required cold clearance of the turbine. This misalignment can be mitigated by heating the bearing support. For example, if the housing heats up during operation, the bearing support is heated such that expansion of the bearing support compensates for expansion of the hot housing and thereby keeps the rotor and housing aligned.

The control of the power supplied to the electric heating device can be performed according to different control schemes. In one example, heating is done on a schedule. During operating state changes, temperature changes in the turbine are known from measurements and calculations. Thus, starting from a defined state, eg a cold turbine at standstill, the typical transients are known, and also the electrical heating required for a particular stator section to minimize gaps as a function of time. Thus, the heat input for the electric heating device can be given, for example, as a function of time. For example, a heating process can start from a defined operating state. The heating process typically starts from a defined steady-state operating point, such as startup of a turbine, or from a steady-state load point.

Heating is also performed depending on the operating parameters of the turbine, such as speed, power, mass flow or operating temperature. Relevant mass flows are, for example, inlet mass flows, exhaust mass flows, fuel flows or injected water or steam mass flows for increasing power or controlling emissions, and cooling air mass flows.

Heating may also be used to control the temperature of at least one section of the housing based on temperature measurements. The temperature of a specific part can be used for multiple temperature measurements and temperature differences or a combination of both.

Additionally, heating may be controlled based on direct measurement of the gap using blade gap sensors and/or vane gap sensors.

During shutdown of the turbine, heat may be transferred to fluid flowing through the machine. For example, air may flow through a gas turbine due to stack draft. Such fluid flows can induce unfavorable temperature distributions in the gas turbine. Furthermore, if parts of the engine are kept hotter to allow for a better restart, this fluid flow can increase heat loss and thus can lead to higher heating needs. According to one embodiment of the method, the inlet and/or outlet of the turbine are closed during stop of the turbine to reduce fluid flow. Accordingly, embodiments of the turbomachine include inlet and/or outlet dampers to close fluid flow paths at the inlet or outlet of the turbine.

Heating control may be limited to certain operating states, such as engine stopped, cool, e.g., at less than 5% RPM (relative to design operating speed), or during running to operating speed and loaded, e.g., at greater than 50% at the rotational speed. Control can be performed with an open-loop or closed-loop controller.

The above gas turbine may be a single gas turbine or a continuous gas turbine such as is known from EP0620363B1 or EP0718470A2. The disclosed methods and methods of use and retrofit can also be applied to single gas turbines or continuous gas turbines.

Description of drawings

The invention, its nature and its advantages will be described in more detail hereinafter with the aid of the accompanying drawings. See attached picture:

Figure 1 schematically shows an example of a turbomachine according to the invention. Here, a gas turbine is given as an example of a turbine.

FIG. 2 schematically shows a detail II of the turbine housing of FIG. 1 with electrical heating arranged in the cooling air supply opening.

Parts List

10 gas turbine

11 compressor inlet gas

12 compressors

13 first combustion chamber

14 first turbo

15 second combustion chamber

16 second turbo

17 Exhaust housing

18 (of the first turbine) stator blades

19 (second turbine) stator blades

20 blade gap sensor

21 Stator blade clearance sensor

22 inner shell wall

23 shell wall

24 first incinerator

25 continuous burners

26 compressor compartment

27 inlet housing

28 rotors

34 Flue gas recirculation (optional)

35 air

36 entrance gate

37 fuel

38 water/steam injection

39 exit gate

40 Electric heating device for connecting wall

41 Electric heating device for inner shell/vane carrier

42 Electric heating device for housing

43 Electric heating in cooling air supply opening

44 Cooling air supply openings

45 bearing support

46 Bearing support heating device

47 exhaust gas

49 connecting walls.

detailed description

Identical or functionally equivalent elements are provided with the same symbols below. The examples do not constitute any limitation of the invention to such arrangements.

An exemplary arrangement is schematically shown in FIG. 1 . The gas turbine 10 is supplied with compressor inlet gas 11 . In the gas turbine 10 , the compressor 12 is followed by a first combustor comprising a first burner 24 and a first combustion chamber 13 . In the first incinerator 24 fuel 37 is added to the compressed gas and the mixture is incinerated in the first combustion chamber 13 . Hot combustion gases are fed from the first combustion chamber 13 into the first turbine 14 followed by a second combustor comprising a continuous burner 25 (also known as a second burner) and a continuous The combustion chamber 15 (also known as the second combustion chamber). Fuel 37 may be added to the gases leaving the first turbine 14 in the continuous burner 35 and the mixture incinerated in the continuous combustion chamber 15 . Hot combustion gases are fed from the continuous combustion chamber 15 into the second turbine 16 .

Steam and/or water 38 may be injected to the primary burner and/or the successive burners for controlling emissions and increasing power output.

A stator of a gas turbine includes a casing. The casing includes a vane carrier or inner casing wall 22 and an outer casing wall 23 . The inner housing wall 22 and the outer housing wall 23 may be connected by a connecting wall 49 . Furthermore, the housing includes an inlet housing 27 and an exhaust housing 17 .

In the example of Fig. 1, the electric heating device for the connecting walls 40 is placed on several connecting walls 49, the heating device for the inner shell 41 is placed on the inner shell wall 22 (also called the vane carrier), and is used The heating device in the housing 42 is placed on the housing wall 23 .

In the example shown in FIG. 1 , the blade clearance sensor 20 is arranged on the inner casing wall 22 at a position facing the rotating blades of the compressor 12 and at a position facing the rotating blades of the first turbine 14 and the second turbine 16 . superior. The vane clearance sensor 21 is arranged at the tips of the vanes in the compressor 12 and on the tips of the turbine vanes 18 , 19 of the first turbine 14 and the second turbine 16 facing the rotor 28 .

The rotor 28 is supported and held in place by bearing supports 45 . The bearing support heating device 46 is arranged on the bearing support 45 so that the bearing support 45 can be heated.

Exhaust gases 47 exit the second turbine 16 . Exhaust gas 47 is typically used in a heat recovery steam generator to generate steam for combined heat and power or for the water steam cycle in a combined cycle (not shown).

Optionally, part of the exhaust gas 47 may be branched in the flue gas cycle 34 (typically downstream of the heat recovery steam generator) and mixed into the inlet air 35 . Typically, recirculation 34 includes a subcooler for cooling the recirculated flue gas.

Furthermore, the compressor inlet may be closed by an inlet damper 36 and the turbine outlet may be closed by an outlet damper 39 .

FIG. 2 schematically shows section II-II of the turbine housing of FIG. 1 . In this region of the second turbine 16 cooling air supply openings 43 are shown. In this example, an electric heating device in the cooling air supply opening 43 is shown in the cooling air supply opening 44 .

Claims (13)

1. A turbine (10) comprising a stator (22, 23, 45, 49) and a rotor (28) arranged to rotate within said stator (22, 23, 45, 49), and at least one electrically heated Means (40, 41, 42, 43, 46) are arranged on at least a part of the surface of said stator (22, 23, 45, 49) for gap control, characterized in that at least one of the electric heating means is arranged bearing support electric heating means (46) on the bearing support; and/or At least one (42) of the electric heating means is arranged to heat a flange connecting the lower and upper half casings of said turbine (10) to reduce or avoid the casing of said turbine (10) ovalization. 2. The turbine (10) according to claim 1, characterized in that the electric heating device (40, 41, 42, 43, 46) is arranged in the cavity of the stator (22, 23, 45, 49) , to heat the fluid at least partially surrounding the stator (22, 23, 45, 49), and/or the electrical heating means (40, 41, 42, 43, 46) by direct mechanical contact arranged on said stator (22, 23, 45, 49) to allow conduction from said electrical heating means (40, 41, 42, 43, 46) to said stator (22, 23, 45, 49) Sexual heat transfer. 3. The turbine (10) according to claim 1 or claim 2, characterized in that the electric heating device (40, 41, 42, 43, 46) is arranged on the stator (22, 23, 49) The cooling air supply openings. 4. The turbine (10) according to claim 1 or claim 2, characterized in that the part of the stator on which the electric heating device (41, 42) is arranged is the inner casing and/or shell. 5. The turbine (10) according to claim 4, characterized in that the electric heating device (40) is arranged on a connecting wall connecting the inner casing with the outer casing. 6. A turbine (10) according to claim 1 or claim 2, characterized in that the electrical heating means (40, 41 , 42, 43, 46) comprise induction heating elements. 7. The turbine (10) according to claim 1 or claim 2, characterized in that a plurality of electric heating devices (40, 41, 42, 46) are arranged around the casing of the turbine (10) along the axis Distributed in the direction and the circumferential direction, and different electric heating devices are constructed and connected to the power supply, so that the different electric heating devices can be independently controlled to control the circumferential direction and the axial direction of the turbine (10) the heating intensity. 8. The turbine (10) according to claim 1 or claim 2, characterized in that the turbine (10) is a gas turbine (10) or a steam turbine. 9. A method for operating a turbomachine (10) comprising a stator (22, 23, 45, 49) and a rotor arranged to rotate within said stator (22, 23, 49) (28), and at least one electric heating device (40, 41, 42, 43) arranged on the surface of at least a part of said stator (22, 23, 45, 49), and said at least one electric heating device ( 40,41,42,43) is controlled to heat at least a portion of said stator (22,23,45,49) for controlling said rotor (28) in relation to said stator (22,23,45,49 ), characterized in that at least one of the electric heating means is a bearing support electric heating means (46) arranged on the bearing support and used to maintain the The rotor (28) is centered relative to the housing; and/or At least one (42) of the electrical heating means is arranged to heat a flange connecting the lower and upper housing halves to reduce or avoid ovalization of said housings. 10. The method according to claim 9, characterized in that at least one electric heating device (40, 41 , 42, 43) is arranged at a position on the upper or lower half of the housing, and at least An electric heating device (40, 41, 42, 43) is controlled to heat the area of the housing where the electric heating device (40, 41, 42, 43) is arranged to reduce the circumferential temperature non-uniformity. 11. A method according to claim 9 or claim 10, characterized in that the at least one electric heating device (40, 41 , 42, 43) is controlled to turn the casing of the turbine in axial direction The temperature profile remains within a predetermined range. 12. The method according to claim 9 or claim 10, characterized in that at least one electric heating device (40, 41 , 42, 43) is arranged at the position of the lower half of the housing, and at least one Electric heating means (40, 41, 42, 43) for heating during shutdown and cooling of the turbine to compensate for the temperature of the upper half of the housing relative to the The temperature of the lower half of the housing is increased to reduce deflection. 13. A method according to claim 9 or claim 10, characterized in that the power supplied to the at least one electric heating device (40, 41 , 42, 43) is based on one of the following: - heating according to the process, - heating according to operating parameters of said turbine (10), such as speed, power, mass flow or operating temperature, - heating based on temperature measurements to control the temperature of at least one section of said housing, - direct measurement of said gap with a blade gap sensor (20) and/or a vane gap sensor (21) and heating to control said measured gap, - Closing the inlet and/or outlet of said turbine (10) during stoppage of said turbine (10) to reduce fluid flow and heat transfer to said fluid in said turbine (10).