SK14995A3 - Steam turbine - Google Patents

Abstract

Described is a stream turbine with a shaft (3) which, at least over part of its length, is located in a housing (4) through which it passes, one end of the housing (4) being the high-pressure end (10) and the opposite end the steam-exhaust end (12). In addition, the housing incorporates a control valve (30) designed to control the rate of steam flow into the housing (4). The invention calls for the shaft bearings to be dry-running, this being achieved by using magnetic bearings (6, 8, 14) located inside the housing (4) at the high-pressure end (10) and at the steam-exhaust end (12). The invention also calls for the control-valve operation to be oil-free, this being achieved by using an electromagnetic actuator (28).

Description

Technical field

The invention relates to a single-shaft steam turbine which is arranged at least in part of its length in a housing and which is guided through the housing, the housing having a high-pressure side and an opposing side of the exhaust steam, and having at least one flow control adjusting valve steam entering the cabinet.

BACKGROUND OF THE INVENTION

When operating a steam turbine, electrohydraulic devices, such as oil-lubricated radial bearings, as well as oil-hydraulically operated adjusting valves with appropriate regulating devices are generally used. Oil-hydraulically operated are also so-called quick shut-off valves acting as quick main shut-off members, and rotary devices adapted to rotate the turbine rotor. However, the use of oil in a steam turbine always carries the risk of fire. Tests conducted so far with non-flammable or hardly flammable liquids have not led to satisfactory results.

SUMMARY OF THE INVENTION

SUMMARY OF THE INVENTION It is an object of the present invention to improve a steam turbine of the type mentioned at the outset in such a way that trouble-free operation is possible while preventing a fire.

According to the invention, the problem is solved in a steam turbine by providing an oil-free shaft bearing by means of magnetic bearings arranged inside the housing on the high pressure side and on the exhaust vapor side and by oil-free operation of the adjusting valve by means of an electromagnetic actuator.

A magnetic bearing and an axial magnetic bearing are arranged inside the housing on the high-pressure side. In addition, a catch bearing is provided on the high-pressure side and is preferably arranged between the radial bearing and the thrust bearing. The magnetic bearing and the retaining bearing are expediently fixed to the turbine housing by means of a flange and are vapor-tightly closed by the lid, so that there is no connection of the steam space provided inside the housing to the surrounding space on the high-pressure side. In such a case, when the shaft is used to drive a working machine, such as a compressor or generator, it passes through the housing to the high pressure side and a lid is provided on the exhaust vapor side. Suitably, however, the shaft is guided on the side of the exhaust vapor through the housing.

On the high-pressure side, a compensating piston is often provided in a steam turbine having a pressurized structure to compensate for displacement with a labyrinth seal.

In such a case, the electromagnetic bearing and the retaining bearing are expediently arranged between the steam space and between this seal, i.e. when viewed from the exhaust vapor side before the seal. This arrangement results in a particularly small distance between the magnetic bearing on the high-pressure side and the magnetic bearing on the exhaust vapor side, which has the advantage that the shaft further approximates the ideal case of the so-called rigid shaft in terms of oscillating technical behavior.

Otherwise, while maintaining the usual distance between the bearings inside the housing, i.e. in the steam space of the turbine, space is retained for additional blade rows. This results in a particularly high degree of turbine efficiency.

In this case, when the shaft on the exhaust vapor side passes through the turbine housing, a seal must be provided between the rotor provided here and between the turbine housing. To accommodate the shaft on the exhaust vapor side, it is expedient to provide a radial magnetic bearing and a further retaining bearing, which are also provided inside the housing. The sealing may be arranged in the direction of the vapor flow, the distances between the bearings may be arranged axially before, between or, to shorten beyond the two bearings. Also a magnetic bearing on the exhaust vapor side of the casing and on the steam side the bearing and radial magnetic bearing retained in front of it.

The electromagnetic actuator, by means of which the adjustment valves for adjusting the inlet of the fresh steam inlet by means of a movable bridge can be jointly controlled, replaces the previously used hydraulic piston actuator. This is inside the cabinet. In addition, it is possible to advantageously arrange the actuator of this, the hydraulic converter can be replaced by an electronic power section, whereby only the electrical wiring is to be routed through the housing. Also the number of electromagnetic actuators, set valves.

it is possible to adjust one that corresponds to the number

Linear drives are expediently used as actuators. The solenoid can be assigned to the valve as well as to the magnet armature which performs linear movement. Then not the beam through which all the adjusting members would be.

put electromagnetic to each adjusting iron core and coil, connected to the rod and which is even needed movable could be simultaneously controlled

Overview of the figures in the drawing

The invention is explained in more detail below with reference to the drawing.

In FIG. 1 is a schematic cross-sectional view of an oil-free steam turbine with magnetic bearings and an electromagnetic actuator.

In FIG. 2 and 3 of the electromagnetic actuator are shown.

other exemplary embodiments

DETAILED DESCRIPTION OF THE INVENTION

Corresponding parts are provided with the same reference numerals in all figures.

In FIG. 1, the steam turbine 1 shown has a turbine rotor 2 arranged on the shaft 3 and a fixed turbine housing 4. The shaft 3 is mounted in two radial magnetic bearings 6 and 8, the magnetic bearing 6 being arranged on the high-pressure side 10 and the magnetic bearing 8 on the side 12 of the exhaust steam of the steam turbine 7. In the steam turbine 7 of FIG.

the shaft 3 on the exhaust steam side 12 passes through the turbine housing 4. In general, however, the shaft 3 can also pass through the turbine housing 4 on the high pressure side 10.

In the exemplary embodiment on the high-pressure side 10, the axial bearing 14 arranged by means of the shaft 3 holds the turbine rotor 2 in the axial direction and absorbs the shear forces generated by the steam. However, the axial magnetic bearing 14 can also be arranged on the exhaust steam side 12.

On the high-pressure side 10 there is also provided a retaining bearing 16 arranged between the bearing 14. On the other side 12 of the exhaust magnetic bearing 6 and 8, the shaft 3 in the present example can be a bearing 6 and which is a magnetic steam bearing bearing downstream.

8. In the event of failure, run down in these embodiments and magnetic is arranged on the vapors behind the radial magnetic bearings of the retaining bearings and 18.

The currently available magnetic bearing coil is suitable for temperatures up to about 400 ° C. However, ° C can be generated in the steam chamber of the steam turbine. It may therefore be necessary as well as retaining bearings 16 and 18 and a steam circulation temperature of up to 540 magnetic bearings 6, 8 and 14.

cool. For this purpose, water can be drawn from the water steam turbine 7. Therefore, no additional units such as pumps or coolers are required. Cooling may be omitted when coil materials suitable for such high temperatures are used. High temperature resistance can be achieved, for example, by ceramic insulation of coil wires.

The high-pressure side, i.e. the front bearing housing, is vapor-tightly closed on the housing 4 by an arranged lid 23, so that there is no connection with the environment. A balancing piston 20 with a labyrinth seal 22, which is arranged on the high pressure side 10 in the exemplary embodiment, is only needed in a pressurized turbine.

A non-contact shaft seal 3 or other seal 24 which is provided on the exhaust vapor side 12 and which can be arranged in the direction of the vapor flow as before, after. but also between the magnetic bearing 8 and the other retaining bearing 18, however, this is necessary in any case, since at this outlet point the shaft 3 is guided through the housing 4.

The housing 4 thus completely surrounds the turbine rotor 2 and the shaft 3 over a portion of its length. Furthermore, the magnetic bearings 6, 8, 14 surround the retaining bearings 16, 18 and the seals 22. 24. The fresh steam supply box 26 forms an electromagnetic actuator of the valves 30, of which a part of the housing 4 is arranged inside the housing 4.

for more shown only

At least one setting one is also

The electromagnetic actuator 28 has an iron core 32 and a coil 34 as well as a magnet armature 38 connected to the rod 36 and a fixed iron core 40. The rod 36 acts on the movable valve bridge 42.

This valve closes the setting steam turbines 6 for these steam

For that

By means of a bridge 42, at the same time, more than perpendicularly to the plane of the drawing, the adjusting valves 30 can be actuated. A screw spring 30 is arranged below the fixed iron core 32, while the pressure force acting by the adjusting valves 30 also causes them to be closed. the force which is supplied from the electromagnetic actuator 28 and which causes the opening of the adjusting valves 30 corresponds at least to the sum of the elastic force of the mechanical helical spring 44 and also of the steam pressure acting on the adjusting valves 30.

The adjusting valves 30 may be actuated by a single solenoid actuator 28, which

Alternatively, however, one can also be associated with each 30. Other possible embodiments are to operate a plurality of actuators 28 on the valve bridge 42, the individual adjusting valve e of the electromagnetic actuator 28 shown in FIG. 2 and 3.

According to FIG. 2, the actuator 28 is arranged next to the lead-in box 26. In this embodiment, the magnet armature 38 is not connected directly by the rod 36, the adjusting valve 30 again being moved by means of 36 movably mounted on the carrier 52, with the housing 4.

The lever 50 is also rigidly connected

The adjusting valves shown in FIG. 30 are in the arrangement 1 and 2 opened by the electromagnetic force of the actuator 28. The actuator 28 can also be arranged to act on the adjusting valves 30 in the opposite force direction so that the electromagnetic force of the actuator 28 closes the adjusting valves 30. . This is particularly useful in the case of rapid closure. In this case, the helical spring must exert less force on the adjustment valves 30 in the closing direction.

Immediate transmission of the movement of the magnet armature 38 to the stem 36 for closing the adjusting valves 30 can be accomplished by an arrangement in which the rod 36 is guided through an opening in the iron core 40 and moved by the magnet armature 38 in the closing direction of the adjusting valves 30. and the aperture provided with the iron core 40 interchanged.

In FIG. 3, the servo drive 28, which is also arranged next to the supply box 26, has a coil 60 that is linearly movable in a substantially time-constant magnetic field. The movement of the coil 60 is transmitted via a lever 50 to the adjusting valve 30. Said magnetic field is generated by a permanent magnet 62, a solenoid 64 with a coil 68, or a combination of a permanent magnet 62 and a solenoid 64 with a coil 68 through superimposing and a magnetic pole. The permanent magnet 62, which is coupled to the iron core 66 and which has the magnetic poles N and S, is surrounded by the coil 68 inside the iron core 67. The electromagnetic Lorentz force acting on the coil 60 is substantially proportional to the current flowing through the coil 60, and depending on its position in the magnetic field.

The permanent magnet 62 may also be replaced by a magnetic soft iron core. When the coils 60 and 68 are operated in series with the same current, then the force on the movable coil 60 is proportional to the square of that current.

In operation of the steam turbine 7 of FIG. 1, the fresh steam passes through the supply box 26 and the adjusting valves 30 into the steam space surrounded by the box 4 and passes through the nozzles 69 to the impeller 70. From there the steam passes through the individual stages, which are made of always more fixed distribution vanes. 72 and more orbital blades 74 mounted on and circulating with the turbine rotor 2. The blade vanes 72 and the blades 74 are vapor-generating in volume. The expanded vapor or waste steam is either process vapor or is fed to a stage greater longer as it expands while expanding through the orifice 76 to the exhaust first utilized as a condenser (not shown) connected to the turbine.

The adjusting valves 30 serve to adjust the force of the fresh steam flowing into the housing 4, their stroke of the adjusting valve 30 being controlled by the coil current in the actuator 28 which is associated with the corresponding adjusting valve 30. The change of this flow is preferably effected by electronic control. For this purpose, the necessary lines are provided in a not illustrated manner via housing 4 to the actuator 28. For the operation of the adjusting valves 30, a proportional integration derivative control is provided, which ensures the control of the stroke of the adjusting valves 30 and changes in its speed.

When using a quick-closing valve, which is generally used as a fast-acting main shut-off member, it is actuated by an electromagnet or electric motor instead of the oil hydraulics to bias the fast-closing spring. The equipment is electromechanical, whereby a spring is used to resiliently engage the valve in front of the valve seat. Otherwise, the electric motor assumes the function of the introduction of the oil-hydraulic rotary device mentioned above.

Such an oil-free steam turbine 7 or also a compressor equipped with magnetic bearings can be operated oil-free as a complete working set or the machine sets are utilized as a fuel consumption. The degree of efficiency of such a machine to low friction losses and due to the low energy of magnetic bearings is considerably high.

The magnetic bearings 6, 8, 14 can also be compensated very well and favorably by the oscillations of the shaft 3, if additional

These advantages are generated in particular by a turbine generator equipped with magnetic bearings and, if it is directly driven by an oil-free steam turbine. The risk of fire is also practically eliminated.

Claims (8)

1. A single-shaft steam turbine which is arranged at least in part of its length in a housing and which is guided through said housing, said housing having a high-pressure side and an opposing side of the exhaust vapor therethrough and having at least one adjusting valve for adjusting the steam flow entering the housing, characterized in that it is provided with an oil-free bearing of the shaft (3) by means of inside the housing (4) on the high pressure side (10) and the exhaust vapor side (12) of the magnetic bearings (6, 8, 14) oil-free operation of the adjusting valve (30) by means of an electromagnetic actuator (28). Steam turbine according to claim 1, characterized in that the magnetic bearing (6, the high-pressure side (10) is a radially magnetic axial magnetic bearing (14). and 14) has a bearing (6) a Steam turbine according to claim 2, characterized in that, in addition to the radial magnetic bearing (6) and the axial magnetic bearing (14), a magnetic catch bearing (14) is provided, which is preferably arranged between the two magnetic bearings (6, 14). ). Steam turbine according to one of the claims 1, characterized in that the high-pressure is vapor-tightly closed by a lid (23). up to 3, s page (10) The steam turbine according to claim (10) of the housing (4) is 14) according to one of claims 1 to 4, characterized in that a seal (22) is provided on the high-pressure side, the magnetic being viewed from the exhaust steam side (12). 1 and 6 (6) arranged prior to this seal (22). 6. A steam turbine according to mark the task s a t ý The steam is inside wardrobes (4) (18); page Italy (12) the seal (24) is within direction or between, preferably downstream of the retaining bearing (18). One of the claims 1 to 5, characterized in that a further exhaust vapor retention bearing arranged in front of the bearing (8) and the further magnetic Steam turbine according to one of Claims 1 to 6, characterized in that the electromagnetic actuator (28) is also arranged inside the housing (4). Steam turbine according to one of Claims 1 to 7, characterized in that the electromagnetic actuator (28) has an iron core (32) and a coil (34) as well as a magnet armature (38) connected to the rod (36).