EP3353385B1 - Turbine with quick-closing valves and regulating valves - Google Patents

Description

The present invention relates to a turbine with a turbine control, a turbine protection, at least one safety block, quick-closing valves and control valves, wherein the quick-closing valves and the control valves via associated switching and actuators can be actuated. Furthermore, the present invention relates to a method for retrofitting an existing turbine having a turbine protection, a turbine control, a hydraulic safety block, quick-closing valves and control valves, wherein the hydraulic quick-closing valves are actuated via associated hydraulic actuators.

Turbines of the type mentioned are known in the art in a variety of configurations. The turbine control is known to take over functions such as power control, pressure control, speed control, valve position control, measurement processing, etc., to name just a few examples. The turbine guard detects any process criteria that may adversely affect the turbine or the operator, and shuts down the turbine as soon as appropriate limits are exceeded. The quick-closing and control valves are responsible for the supply, control and shut-off of the working fluid to the steam turbine during operation. Currently, the "open and close" functions of quick-acting valves and "open, close and close" of control valves are primarily controlled by hydraulic actuators via a central hydraulic safety block and the turbine control, which in turn feeds into the turbine's control and regulating oil system are involved.

Quick-acting valves usually work with pilot control, which is why not too large valve forces are to be handled. Against this background, the quick-acting valves do not provide any decisive components in the selection of the Oil systems dar. They usually come with low pressure oil systems from 8 to 12 bar.

Control valves can basically be divided into two groups, namely in pressure relief valves with design-related permeability and low actuating forces, such as unloaded pipe valves without advance, single-seat valves with preheating or double seat valves, and in non-pressure-relieved but completely tight seat valves with high restoring forces, such as Thumb or mushroom valves, pre-stroke valves or pipe valves with forward stroke. The relieved control valves usually come with low-pressure hydraulics from 8 to 12 bar. Unloaded control valves require a medium-pressure hydraulics of 30 to 50 bar or a high-pressure hydraulics of 100 to 160 bar, depending on the pressure of the working fluid.

EP1026368 discloses a steam turbine wherein the live steam is supplied via hydraulically driven quick-closing valves and control valves.

DE 1946968 U discloses a pneumatic actuator with a spring-loaded diaphragm or a spring-loaded piston, characterized in that the actuating rod protrudes at both ends of the actuator and in this way, both pressure forces and tensile forces can be generated without changing the actuator. EP2110592 A2 discloses a drive with an electric motor such as a permanent-magnet synchronous motor and a linear unit with a piston rod which is guided in a movement thread of a movement threaded nut and formed as a spindle.

EP 2620655 A1 discloses a drive system having a fluid flow source for generating pneumatic or hydraulic forces to drive the valve portion of the valve.

US 3556463 A relates to a shut-off valve for controlling the supply of a pressure medium in a medium receiving device.

A major disadvantage of turbines of the type described above is that the control and regulating oil system is very costly in terms of planning, purchase, installation, testing, commissioning and maintenance. In addition, in the case of oil leaks, especially at the hot front end of the turbine, a high risk of fire, which is associated with a corresponding risk to the turbine itself and the operating personnel.

Based on this prior art, it is an object of the present invention to provide a turbine of the type mentioned above with an alternative structure, which at least partially eliminates the problems described above.

To achieve this object, the present invention provides a turbine of the type mentioned, which is characterized in that it is at least one safety block to a pneumatic safety block, and that at least one switching drive for direct or indirect actuation of a quick-closing valve is a pneumatic switching drive , By direct operation is meant that the pneumatic switching drive acts directly on the valve stem of the quick-acting valve. In the case of indirect actuation, the pneumatic switching drive can form, for example, a component of a control device of a medium-operated quick-acting valve. By using a pneumatic switching drive instead of a hydraulic switching drive for switching a quick-acting valve, which is arranged for example in the region of the hot front end of the turbine, the risk of fire can be significantly reduced. As a result, high security for the turbine itself and the operating personnel is achieved. In addition, insurance costs can be reduced. Another advantage is that pneumatic shift actuators compared to hydraulic actuators represent a simple, robust and cost-effective alternative. In addition, pneumatic actuators are very reliable, have only one Low wear and can be easily integrated into the turbine protection. Accordingly, associated with the use of pneumatic actuators low costs.

According to one embodiment of the present invention, all the switching drives for actuating the quick-acting valves are pneumatic switching drives. In this way, the advantages described above are used optimally.

Preferably, the turbine protection and the at least one pneumatic safety block are designed and set up in such a way that they are used to control the pneumatic switching drive or the pneumatic switching drives. In other words, the control of the pneumatic shift actuators is easily integrated into the existing turbine protection, which also leads to a cost-effective design.

The pneumatic safety block advantageously has a plurality of series-connected 5/2 way valves, in particular three 5/2 way valves in 2 of 3 circuit. With such a construction of the pneumatic safety block, the functions "opening, closing, venting and testing" can be realized without problems. The main advantage associated with three 5/2 directional valves connected in series is that safe operation of the turbine is possible even if one of the directional control valves should fail. Accordingly, downtimes of the turbine are avoided in the event of failure of one of the directional control valves. In principle, it is of course also possible to use 3/2 way valves.

According to one embodiment of the present invention, electric actuators and / or hydraulic actuators with self-sufficient oil supply are provided for actuating the control valves, which are operated in particular with a flame-retardant liquid. Electric actuators can be used instead of hydraulic actuators especially when it comes to the control valves to be operated is relieved control valves. Hydraulic actuators with self-sufficient oil supply, however, are used in particular in non-pressure relieved control valves. If all the control valves are replaced by electric actuators and / or hydraulic actuators with self-sufficient oil supply, so can be dispensed with a central control and regulating oil system entirely, which is associated with a significant cost savings. It would then remain only the lubricating oil system, which is normally operated at about 2 bar. If the hydraulic actuators are operated with a self-sufficient oil supply with a flame retardant fluid, so the risk of fire is reduced to a minimum.

To achieve the object mentioned above, the present invention also proposes a method for retrofitting an existing turbine, which has a turbine protection, a turbine control, a hydraulic safety block, quick-closing valves and control valves, the quick-closing valves are directly or indirectly actuated via associated hydraulic actuators. The retrofitting method according to the invention is characterized in that at least one hydraulic switching drive of a quick-acting valve is replaced by a pneumatic switching drive, and that a pneumatic safety block is provided which at least partially replaces the functions of the hydraulic safety block.

In the method according to the invention, all hydraulic shift drives are preferably replaced by pneumatic shift drives, which is accompanied by the advantages described above.

Advantageously, the control is modified such that the at least one pneumatic switching drive is controlled via the turbine protection and the pneumatic safety block, which is accompanied by a very simple and inexpensive construction.

According to one embodiment of the method according to the invention, at least one hydraulic actuator is replaced by an electric actuator.

According to a further embodiment of the invention, in addition or alternatively, at least one hydraulic actuator, which is connected to a central control and regulating oil system of the turbine, replaced by a hydraulic actuator with self-sufficient oil supply.

Advantageously, the turbine control is modified such that the at least one electric actuator and / or the at least one hydraulic actuator is controlled with autonomous oil supply via the turbine protection and the turbine control.

Further features and advantages of the present invention will become apparent from the following description of an embodiment of a turbine according to the invention with reference to the accompanying drawings.

Figur 1

eine schematische Ansicht einer Hochdruck-Ventilgruppe einer Turbine gemäß einer Ausführungsform der vorliegenden Erfindung;

Figur 2

eine schematische Ansicht, die ein Steuergerät eines mediumbetätigten Schnellschlussventils der in Figur 1 dargestellten Hochdruck-Ventilgruppe zeigt;

Figuren 3 - 8

schematische Ansichten, die einen pneumatischen Sicherheitsblock in verschiedenen Betriebsstellungen zeigen; und

Figur 9

eine schematische Ansicht, die ein weiteres Schnellschlussventil gemäß einer Ausführungsform der Erfindung zeigt, das in Figur 1 nicht dargestellt ist.

This is / are

FIG. 1

a schematic view of a high pressure valve group of a turbine according to an embodiment of the present invention;

FIG. 2

a schematic view showing a control unit of a medium-operated quick-closing valve of the FIG. 1 shown high-pressure valve group shows;

FIGS. 3 to 8

schematic views showing a pneumatic safety block in different operating positions; and

FIG. 9

a schematic view showing a further quick-acting valve according to an embodiment of the invention, which in FIG. 1 not shown.

FIG. 1 schematically shows a turbine 1, which in the present case is a steam turbine. The turbine 1 includes in a known manner a turbine control 2 and a turbine protection 3. The turbine control 2 takes over functions such as power control, pressure control, speed control, valve position control, measured value preparation, etc., to name but a few examples. The turbine protection 3 detects all process criteria that can have a negative effect on the turbine 1 or on the operating personnel, and shuts off the turbine 1 as soon as corresponding limit values are exceeded. The turbine 1 has a number of valve groups, of which in FIG. 1 an example of a high-pressure valve group 4 is shown. In the present case, the high-pressure valve group 4 comprises a quick-closing valve 5 and three control valves 6, which are responsible for supplying, regulating and shutting off the live steam, which flows in the direction of the arrows 7 through a live steam path 9 formed in a housing 8 in the direction of the high-pressure stage during turbine operation. In the present case, the quick-acting valve is a medium-actuated quick-acting valve whose pilot control cone 10 and main cone 11 are moved into the "open" or "closed" positions as a function of the switching position of a control unit 12 via the live steam. For this purpose, control lines 13 and 14 are provided which connect the quick-release valve 5 to the control unit 12. The control unit 12 comprises a pneumatic switching drive 15, which in the present case is designed as a membrane drive. The switching drive 15 comprises a switching drive housing 16, which is provided with an air connection 17 and is divided in the interior via a membrane 18 into two chambers 19 and 20, wherein the membrane 18 by return springs 21, which are arranged in the chamber 19 without compressed air connection 17 are held in a starting position. On the diaphragm 18, a spindle 22 is fixed, which is connected by means of a spindle coupling 23 with the valve spindle 24 of the control unit 12 and seals opposite valve seats 25a and 25b according to the switching position. In the starting position, the live steam is released via the control line 14 to the control line 13 and ultimately acts on the main cone 11 of the quick-closing valve 5, which assumes the "closed" position. The outlet 26 to the atmosphere or leakage steam line is closed. If the chamber 20, starting from the in FIG. 2 Compressed air is applied to the initial position shown, the valve spindle 24 is moved via the diaphragm 18 with the spindle 22 from the valve seat 25 a to the valve seat 25 b until it is sealed, the control line 14 closes and in this way the outlet 26 as well as a control channel 27 of the quick-closing valve 5 is opened to the atmosphere. This also a cylinder chamber 28 via a throttle 29 and a gap surface 30 and a cylinder chamber 31 via a bore 32 and the main cone 11 of the quick-closing valve 5 is depressurized. The pressure of the live steam keeps the pilot poppet 10 via the inlet bores 33 and the main poppet 11, respectively counter to the force of a spring 34, in the open position, both in the rear end position the passage of the live steam into the cylinder chamber 28 and in the control line 13 without leakage Shut off. Accordingly, the live steam can flow via an inlet screen 35 to the downstream control valves 6.

The triggering of the quick-closing valve 5 takes place by relieving the air pressure at the control unit. Accordingly, the chamber 20 of the switching drive 15 is not pressurized with compressed air. The control line 13 is closed to the atmosphere by the valve stem 24 is pressed by the spring force of the return springs 21 via the spindle 22 with spindle clutch 23 on the valve seat 25b and subjected to the live steam pressure. The cylinder chamber 28 is via the control line 13, the control channel 27 and the inflow bore 33 also pressurized. The pilot poppet 10 thus receives a compressive force against the opening force, with the steam forces on the pilot poppet 10 compensate and this goes through the force of the spring 34 in the closed position. Accordingly, the cylinder chamber 28 is acted upon via the inlet bores 33, an open control channel 36 and bores 37 and via the adjustable throttle 29 and the gap surface 30 with the pressure of the live steam. The main cone 11 thus receives an opening force opposing pressure force. The compressive forces on the main cone 11 are equalized, whereby it is closed by the force of the spring 34 and pressed against the associated valve seat.

The FIGS. 3 to 8 show various functional positions of a pneumatic safety block 38 which is connected to the turbine protection 3 and designed to control the pneumatic switching drive 15 of the controller 12 of the quick-closing valve 5. The safety block 38 comprises three identically constructed, electromagnetically actuated 5/2 directional control valves V1, V2 and V3 with spring return, which are arranged in series in 2 of 3 circuit, two pressure ports P1 and P2, a test port P3 and one with the compressed air port 17 of the switching drive 15 of the quick-closing valve 5 connected pressure output E1.

In the in FIG. 3 shown starting position none of the directional control valves V1, V2 and V3 is actuated, so that neither at the pressure outlet E1 nor at the test port P3, a pressure is applied. Accordingly, the main cone 11 of the quick-closing valve 5 is in its closed position.

Are all three-way valves V1, V2 and V3 operated, as in FIG. 4 is shown, there is a pressure on both the test port P3 and the pressure output E1. Accordingly, the quick-closing valve 5 is transferred to its open position, so that the live steam can flow in the direction of the control valves 6.

If two of the three directional control valves V1, V2 and V3 are actuated, a pressure is present at the pressure outlet E1, one of the channels being depressurized to the directional control valves V1, V2 and V3 and being connected to the test port P3.

To achieve a closed position of the quick-closing valve 5 at least two of the three-way valves V1, V2 and V3 must be transferred to the unactuated position, as in the FIGS. 6 . 7 and 8 is shown. Basically, an actuation of the switching drive 15 and the quick-closing valve 5 with reference to the FIGS. 4 to 8 So also possible if one of the directional valves V1, V2, V3 should be defective, so that downtime of the turbine 1 can be avoided due to defective valves.

In the present case, the control valves 6 are double-seat control valves, each having two main cones 39 connected to one another, to which corresponding valve seats formed on the housing 8 are assigned. The main cone 39 of the in FIG. 1 arranged rightmost control valve 6 are coupled to a spindle of an electric actuator 41, which in turn is connected to the turbine control 2 and the turbine protection 3, so that the main cone 39 moves under actuation of the actuator either in a closed position or in a fully or partially open position can be. The main cones 39 of the other two control valves 6 are in turn transferred via the connected to the actuator 41 control valve in its fully or partially open position. To move the main cone 39 in its closed position each return springs 42 are provided. Instead of the electric actuator 41, in principle, a hydraulic actuator with self-sufficient oil supply can be provided, which is advantageously operated with a flame-retardant liquid, even if this is not shown here. Such hydraulic actuators with self-sufficient oil supply are known in the art, Therefore, a more detailed explanation is omitted here.

In the above-described construction of the high-pressure valve group 4, the quick-closing valve 5 is controlled via the turbine guard 3 and the pneumatic safety block 38, and the control valves 6 are controlled via the turbine control 2 and the turbine guard. Accordingly, it is possible to dispense with a central control and regulating oil system, which entails a great cost reduction as well as a minimization of the risk of fire arising from such a control and regulating oil system in the event of a leak. This also applies if instead of the electric actuator 41, a hydraulic actuator is used with self-sufficient oil supply.

Even if in FIG. 1 only the high pressure valve group 4 of the turbine 1 is illustrated, the present invention is not limited to such a high pressure valve group. Rather, according to the invention are all switching and actuators of quick-closing and control valves of the turbine 1, but at least all switching and actuators of Schnellschluss- and control valves at positions with high risk potential, in particular at the hot front end of the turbine 1, in the manner described above executed. Furthermore, it should be clear that this also applies to such quick-closing and control valves, which have a different structure than the valves 5 and 6 shown. Even if in FIG. 1 As an example of a quick-closing valve, a medium-operated quick-acting valve is shown, it should also be noted that directly operated quick-acting valves can be equipped with a pneumatic switching drive of the type described above. In such directly operated quick-acting valves, the pneumatic switching drive then acts directly on the spindle of the quick-acting valve. Depending on the quick-closing valve type, the direction of action of the switching drive can be retracted or extended in the unpressurized state with the spindle. A structural design of a quick-closing valve 5 with extended spindle, in which it in the present case is a single seat quick-release pre-stroke shows FIG. 9 ,

In the housing 8 is a Vorhubspindel 43, which forms a unit, called Vorhubventil with the main cone 44, which is moved by a pneumatic switching drive 15 in the "open" or "closed" position. The Vorhubspindel 43 is guided in the lid 45 and sealed by a packing 46 of the prior art to the atmosphere. The switching drive 15 is a diaphragm drive as already described and consists of a switching drive housing 16, which is provided with an air connection 17 and is divided in the interior via a membrane 18 into two chambers 19 and 20, wherein the membrane 18 by the return springs 21, which in the chamber 19 are arranged without compressed air connection 17, is held in a starting position. On the spring-loaded diaphragm 18, a spindle 22 is attached, which is connected by means of a spindle clutch 23 with the Vorhubspindel 43 and the main cone 44 presses in a valve seat 47 and seals in the "closed" position. If now the quick-closing valve 5 is subjected to live steam pressure in a chamber 48, this position "valve closed" will continue to exist.

If the chamber 20 is acted upon from the starting position with compressed air, the Vorhubspindel 43 is moved via the diaphragm 18 with spindle 22 from the valve seat 51 in the interior of the main cone 44 and the steam flow through a bore 52 of the main cone 44 to a space 49 in front of the closed Control valves released. After this space 49 has filled with steam and has reached about 75-80% of the live steam pressure, the main cone 44 lifts off from the valve seat 47 and moves to the cover 45 until it has reached the end position "valve open". The steam flow can now flow through a steam strainer 50 to the downstream control valves.

The triggering of the quick-closing valve 5 is carried out by relieving the air pressure on the switching drive 15. Accordingly the air flow into the chamber 20 of the switching drive 15 is interrupted and switched to the atmosphere. Thereby, the steam force is overcome in the opening direction of the Vorhubspindel 43 with the main cone 44 by the spring force of the return springs 21 via the spindle 22 with spindle clutch 23 and moves in the closing direction until the valve seat 47 is again vapor-tight. Thus, the starting position "valve closed" is reached again and acted on the Vorhubventil with live steam pressure.

The partial stroke test of the quick-action valve 5 can, similar to the hydraulic drive, be realized by opening an additional solenoid valve in the supply air line. In the chamber 20, the pressure is slowly lowered until the Vorhubventil moves under the spring force of the return springs 21 from the end position in the direction "close". A position change of 15-20% is sufficient for the partial stroke test.

In addition, the present invention proposes to convert an existing turbine comprising a turbine protection, a turbine control, a hydraulic safety block, quick-acting valves and control valves, wherein the quick-acting valves can be actuated via assigned hydraulic switching drives, such that the hydraulic switching drives of the quick-acting valves at least partially but preferably be completely replaced by pneumatic switching actuators, and that a pneumatic safety block is provided which replaces the functions of the hydraulic safety block at least partially. In addition, hydraulic actuators of control valves of the existing turbine are preferably replaced by electric actuators and / or by hydraulic actuators with self-sufficient oil supply, so that it is possible to dispense with the entire control and regulating oil system of the existing turbine.

Although the invention has been illustrated and described in detail by the preferred embodiment, the invention is not limited by the disclosed examples and other variations can be deduced therefrom by the person skilled in the art, provided that they do not depart from the scope of protection defined by the claims.

Claims (13)

1. Turbine (1) having a turbine regulation unit (2), a turbine protection unit (3), at least one safety block (38), quick-closing valves (5) and regulating valves (6), wherein the quick-closing valves (5) and the regulating valves (6) are able to be actuated via assigned switching and actuating drives (15, 41),
   characterized in that
   the at least one safety block (38) is a pneumatic safety block, and in that at least one switching drive (15) for directly or indirectly actuating a quick-closing valve (5) is a pneumatic switching drive.
2. Turbine (1) according to Claim 1,
   characterized in that
   all the switching drives (15) for actuating the quick-closing valves (5) are pneumatic switching drives.
3. Turbine (1) according to Claim 1 or 2,
   characterized in that
   the turbine protection unit (3) and the at least one pneumatic safety block (38) are designed and configured such that, via these, the control of the pneumatic switching drive (15) or of the pneumatic switching drives is realized.
4. Turbine (1) according to one of the preceding claims,
   characterized in that
   the pneumatic safety block (38) has a plurality of 5/2 directional valves (V1, V2, V3) connected in series.
5. Turbine (1) according to Claim 4,
   characterized in that the pneumatic safety block (38) has three 5/2 directional valves connected in series in a 2-of-3 circuit.
6. Turbine (1) according to one of the preceding claims,
   characterized in that,
   electrical actuating drives (41) and/or hydraulic actuating drives with autonomous oil supply, which are in particular operated with a liquid of low flammability, are provided for actuating the regulating valves (6).
7. Turbine (1) according to Claim 6,
   characterized in that
   the turbine protection unit (3) and the turbine regulation unit (2) are designed and configured such that, via these, the control of the electrical actuating drives (41) and/or the control of the hydraulic actuating drives with autonomous oil supply is realized.
8. Method for retrofitting an existing turbine having a turbine protection unit (3), a turbine regulation unit (2), a hydraulic safety block, quick-closing valves (5) and regulating valves (6), wherein the quick-closing valves (5) are able to be actuated directly or indirectly via assigned hydraulic switching drives,
   characterized in that
   at least one hydraulic switching drive of a quick-closing valve (5) is replaced by a pneumatic switching drive (15), and
   in that a pneumatic safety block (38) which at least partially replaces the functions of the hydraulic safety block is provided.
9. Method according to Claim 8,
   characterized in that
   all the hydraulic switching drives are replaced by pneumatic switching drives (15).
10. Method according to Claim 8 or 9,
    characterized in that
    the control is modified such that the at least one pneumatic switching drive (15) is controlled via the turbine protection unit (3) and the pneumatic safety block (38).
11. Method according to one of Claims 8 to 10,
    characterized in that
    at least one hydraulic actuating drive is replaced by an electrical actuating drive (41).
12. Method according to one of Claims 8 to 11,
    characterized in that
    at least one hydraulic actuating drive, which is connected to a central control- and regulation-oil system of the turbine, is replaced by a hydraulic actuating drive with autonomous oil supply.
13. Method according to Claim 11 or 12,
    characterized in that
    the turbine regulation unit (2) is modified such that the at least one electrical actuating drive (41) and/or the at least one hydraulic actuating drive with autonomous oil supply are/is controlled via the turbine protection unit (3) and the turbine regulation unit (2).

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