Hydraulic control device for an emergency stop valve of a steam turbine and steam turbine arrangement

Abstract

A hydraulic control device for an emergency stop valve of a steam turbine has a module for reducing a hydraulic pressure by rapid opening of an outflow valve and/or unloading or loading an actuator for actuating the emergency stop valve. In an operating medium supply and/or conducting system a control valve arrangement with at least three safety valves is provided, which are hydraulically interconnected such that they open the outflow valve or unload or load the actuator only when a safety circuit by way of at least two safety valves of the control valve arrangement has assumed an emergency stop position. A precontrol valve that is independent from the remaining safety valves is hydraulically connected upstream of each safety valve. A safety valve that is connected downstream of a respective precontrol valve can be hydraulically decoupled from the same during the operation.

Claims

1. A hydraulic control device for an emergency stop valve of a steam turbine, comprising: a module for reducing a hydraulic pressure by rapid opening of an outflow valve and/or changing a load on an actuator for actuating the emergency stop valve; a control valve arrangement with at least three safety valves provided in an operating medium supply and/or conducting system, said at least three safety valves being hydraulically interconnected to open the outflow valve or change a load on the actuator only when a safety circuit by way of at least two safety valves of said control valve arrangement have assumed an emergency stop position; at least three precontrol valves, with a respective said precontrol valve hydraulically connected upstream, in a flow direction from a pressure source towards a pressure sink, of each said safety valve and independent from remaining said safety valves, wherein the respective said safety valve that is connected downstream of a respective said precontrol valve can be hydraulically decoupled from the respective said precontrol valve during operation, and wherein said three precontrol valves are connected in parallel.

2. The control device according to claim 1, wherein said three precontrol valves are hydraulically coupled to one another.

3. The control device according to claim 2, which comprises a common connection line with a pressure source and a common connection line with a pressure sink hydraulically coupling said precontrol valves to one another.

4. The control device according to claim 1, wherein each individual said precontrol valve is configured to assume at least two valve positions, namely: a first valve position, in which a connector for direct or indirect coupling of said precontrol valve to a pressure source is fluidically connected with a connector for a direct or indirect fluidic connection with a connector on said safety valve; and a second valve position, in which a connector for direct or indirect coupling of said precontrol valve with a pressure source is fluidically separated from a connector for direct or indirect fluidic connection with a connector on said safety valve.

5. The control device according to claim 1, wherein each said precontrol valve is a multiple transfer valve.

6. The control device according to claim 5, wherein each said multiple transfer valve is a 6/2-way valve.

7. The control device according to claim 1, wherein each said safety valve is a safety transfer valve, comprising: at least two connectors including a connector for direct or indirect coupling with a pressure source and a connector for direct or indirect coupling with a pressure sink; at least two valve positions, including: a first valve position in which said connector on said safety transfer valve for fluidic connection with said precontrol valve connected upstream of the respective said safety transfer valve is fluidically disconnected or shut off with a connector on said safety transfer valve (1.5) for coupling with a pressure sink; and a second valve position in which said connector on said safety transfer valve for fluidic connection with said precontrol valve connected upstream of the respective said safety transfer valve is fluidically connected to a connector on said safety transfer valve for coupling with a pressure sink.

8. The control device according to claim 7, wherein each said safety transfer valve is a multiple transfer valve, comprising two connectors in each case for a fluidic connection with connectors on said precontrol valve connected upstream of said safety transfer valve, a connector for coupling with a pressure sink, and a connector for a fluidic coupling with a connector on one of the other said precontrol valves.

9. The control device according to claim 8, wherein each said safety transfer valve is a 4/2-way valve.

10. The control device according to claim 1, which further comprises a test control valve arrangement including at least one transfer valve for carrying out a partial stroke test.

11. The control device according to claim 10, wherein said at least one transfer valve of said test control valve arrangement is one of two 2/2-way valves arranged in series.

12. The control device according to claim 1, which comprises an external outflow valve connected between the actuator interacting with the emergency stop valve and the module.

13. A steam turbine arrangement, comprising a steam turbine, a steam mass flow supply assigned to said steam turbine, and an emergency stop valve in said steam mass flow supply, and a hydraulic control device according to claim 1 assigned to said emergency stop valve.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) The solution according to the invention is explained in the following by way of figures. There:

(2) FIG. 1 shows a control device for operating a turbine with an emergency stop valve during normal operation;

(3) FIG. 2 shows a control device according to FIG. 1, however, compared with FIG. 1, with a defective safety transfer valve (MV1) and an external outflow valve;

(4) FIG. 3 shows a control device according to FIG. 2, however, compared with FIG. 2, with a circuit arrangement for removing the safety transfer valve (MV1) during running operation and an external outflow valve;

(5) FIG. 4 shows a control device according to FIG. 1, however, compared with FIG. 1, with triggered emergency stop valve and an external outflow valve.

DESCRIPTION OF THE INVENTION

(6) FIG. 1 shows a control device 1 with a module M for operating a turbine 4, in particular steam turbine 4 with an emergency stop valve 2 during normal operation. The hydraulic control device 1 for an emergency stop valve 2 of a steam turbine 4 comprises a module M for reducing a hydraulic pressure through quick actuation, in particular opening of a valve, here of an outflow valve 1.6 and/or for loading or unloading an actuator 3 for actuating the emergency stop valve 2, here for unloading the actuator 3 in the form of a cylinder-piston arrangement by way of the opening of the outflow valve 1.6 and a control valve arrangement 6 arranged in an operating medium supply and/or conducting system 5. The control valve arrangement 6 to this end comprises at least two, preferentially, as reflected in FIG. 1, three safety valves which are hydraulically interconnected in such a manner that these only open the outflow valve 1.6 when a safety circuit by way of at least two safety valves, here safety transfer valves 1.5 of the control valve arrangement, have moved into a position which is also described as emergency stop position. The safety valves in this case are designed as safety transfer valves 1.5, preferentially as electromagnetically actuatable multiple transfer valves, in particular 4/2-way valves MV1, MV2 and MV3 and characterized by at least two switching positions. A first switching position I in this case blocks the connection between a connector on the valve that can be connected to a pressure medium source, in particular pump Pu and a pressure trough, in particular tank Ta, while in the second switching position II there is the connection between the connector on the valve that can be connected with a pressure medium source and a pressure trough, or a connector on the valve that can be connected with the pressure trough.

(7) According to the invention, a precontrol valve 1.4 in the form of a multiple transfer valve is hydraulically connected upstream each safety valve, in particular safety transfer valve 1.5, wherein the individual precontrol valve 1.4 is designed in such a manner to make possible in at least one valve position a hydraulic shutting-off of the safety valve 1.5 connected downstream of the same. Hydraulically connected upstream means that the safety valve 1.5 in through-flow direction between pressure source Pu and pressure trough Ta is arranged downstream of the precontrol valve 1.4 and there is a fluid-conducting connection between an individual precontrol valve 1.4 and a safety valve 1.5. The individual precontrol valve 1.4 is characterized by at least two switching positions, wherein one of the two switching positions corresponds to the valve position which makes possible a hydraulic shutting-off or decoupling of the safety transfer valve 1.5 from the precontrol valve 1.4.

(8) The shown module M, in a particularly advantageous embodiment, each comprises three such safety transfer valves 1.5 and in each case a precontrol valve 1.4 connected upstream of the safety transfer valves 1.5. In this way it is achieved that for realizing the emergency stop function at least two of the safety transfer valves 1.5 always have to be in the first switching position intended for this purpose.

(9) In FIG. 1, the control device 1 and in particular the valve position during normal operation are reflected. The pump Pu pumps the control fluid present in the lines into the precontrol valves 1.4 that are located in a first position I. In the same, there is a hydraulic connection to the safety transfer valve 1.5 arranged downstream of the individual precontrol valve 1.4, in particular the connector provided on the valve for the direct or indirect connection with a pressure medium source via further units arranged in between. The individual precontrol valve 1.4 is opened, so that the control fluid is conducted from the respective precontrol valves 1.4 to the multiple transfer valves 1.5. After the voltage supply (not shown in the drawings) has been switched on, the safety multiple transfer valves 1.5 attract and take up the position I shown in FIG. 1. In this first valve position I, the shown multiple transfer valves 1.5 are closed, i.e. there is no fluid-conducting connection between the connector for the direct or indirect coupling with the pressure medium source and the connector for the direct or indirect coupling with the pressure trough. The connections in terms of fluid of connector P (in the region of the pump Pu as pressure medium source) and connector T (in the region of the tank Ta as pressure medium trough) are thus closed. The control fluid which flows in via an adjustable throttle 1.9 and a non-return valve 1.7 in the region of the connector P with the pump Pu flows via a connector A into the actuator 3, where it actuates the piston rod and actuates the emergency stop valve 2 connected thereto.

(10) When two or three safety transfer valves 1.5 in any combination or order are switched off, the connection between the connector P and the connector T is established. The control fluid can flow out into the tank Ta. The control fluid of the actuator 3 then flows off via an outflow valve 1.6 to the tank Ta. The emergency stop time is dependent on the spring force of the actuator 3.

(11) The emergency stop can also optionally (shown in dashed line in FIG. 1: in the remaining ones, shown as being present) be supported additionally via an external outflow valve 1.10. By use of an externally attached outflow valve 1.10, the emergency stop time, dependent on the rated size of the valve, can be correspondingly shortened. The coupling-up in terms of fluid is effected via the connector X on the control device 1, in particular the module M.

(12) For checking the emergency stop valve 2 and its function, a test control valve arrangement 1.3 is provided. The same comprises a first multiple transfer valve 1.1, here a 2/2-way valve and two further multiple transfer valves 1.2, here 2/2-way valves MV4 and MV5. When the multiple transfer valves 1.2 are switched, the actuator 3 moves out of its corresponding position. The module M and the test control valve arrangement 1.3 preferably form a structural unit. In particular, these two part units can form a compact block and be fastened to one another and/or a carrier. This facilitates the assembly of the complete control device 1 and reduces the required installation space. The module M and/or the test control valve arrangement 1.3 preferably comprise an end position monitoring device in order to determine whether the valves operate properly, i.e. assume the activated end position (open or closed position).

(13) The safety transfer valves 1.5, in particular multiple transfer valves MV1, MV2 and MV3 are preferably designed as 4/2 way solenoid valve. Preferably, valves of the module M in this case connect the actuator 3 with the tank Ta formed as pressure trough or separate it from the pump Pu formed as pressure source when they are not supplied with energy, i.e. in the currentless state open the emergency stop valve 2. In the same way, the first and/or second transfer valve 1.2, here 2/2-way valve MV4 and/or MV5 of the test control valve arrangement 1.3 preferably connect the emergency stop valve 2 with the pressure trough, while they separate the same from the pressure source, when they are supplied with energy, i.e. close the emergency stop valve 2 in the energized state. However, the obverse currentless position is also possible.

(14) The precontrol valve 1.4 formed as multiple transfer valve is preferentially designed for realizing a wide range of functions as 6/2-way valve. In the operating mode described in FIG. 1, the same is located in the position I. In position I of the 6/2-way valve, the inlet Z1 is connected with the outlet A2, the inlet Z3 with the outlet A4. Inlet Z5 and outlet A6 are closed. Outlet A2 and outlet A4 in turn are connected in terms of fluid with the corresponding safety transfer valve 1.5.

(15) FIG. 2 reflects a situation in which the safety transfer valve 1.5 with the designation MV1 is defective. The same remains for example in the opened position II while the other multiple transfer valves MV2 and MV3 are in the valve position I. In order to now replace MV1 the precontrol valve 1.4 corresponding with the same, in particular multiple transfer valve has to be actuated and from its position I shown according to FIG. 1 transferred into the at least one further position II. In this position IIreflected in FIG. 3the inlet Z1 and Z5 is connected with the outlet A6. The further inlet Z3 and the further outlets A2 and A4 are closed. The outlet A6 is connected in terms of fluid with the further safety transfer valves 1.5 with the designation MV2 and MV3. Both safety transfer valves 1.5 with the designation MV2 and MV3 are in the closed position I.

(16) When the position of the multiple transfer valve 1.4 shown in FIG. 3 is reached, the safety valve 1.5 connected downstream of the same, here MV1, can be removed and replaced during running operation. The switching logic for the actuation of the emergency stop valve 2 automatically changes from a 2oo3 trip into a 1oo2 (one out of two).

(17) When two or three safety transfer valves 1.5 are switched off in any combination or orderas for example reflected for the safety transfer valves MV2 and MV3 in FIG. 4, the connection between the connector P and the connector T is established. The control fluid can flow off into the tank Ta. The control fluid of the actuator 3 flows off to the tank Ta via an outflow valve 1.6. In addition, the external outflow valve 1.10 supports in terms of shortening the emergency stop time.

(18) A reliable over speed protection is indispensible for turbomachines. For gas and steam turbines, this means a safe detection of the over speed and as reaction an immediate closing of the emergency stop valve. This hydraulic control device offers both functions in one device. An electronic evaluation unit detects the over speed and an electrohydraulic assembly assumes the direct activation of the emergency stop valve 2.

(19) The switchability of the individual valve devices is realized by way of suitable actuating devices. The switchability of the safety valves, which is characterized by realizing the at least two valve positions, can be realized in different ways here. Preferentially, electromagnetic actuating devices are employed. The actuating devices of the precontrol valves 1.4 can be actuated mechanically, electrically, hydraulically or in other ways. Preferentially, these are actuated manually mechanically against spring force in the event of replacement.

(20) In all figures, the connectors mentioned in the following are reflected on the module M:

(21) Connector P to the pump Pu, connector T to the tank Ta, connector MMV1 to MV1, connector MMV2 to MV2, connector MMV3 to MV3, connector MMV4 to MV4, connector MMV5 to MV5, connector X to the outflow valve 1.10, connector A to the actuator 3 in the bypass to the outflow valve 1.10. Also reflected is a throttle 1.8 and 1.9 in the connection to the pump Pu and to the outflow valve 1.10 and the actuator 3 respectively.

LIST OF REFERENCE CHARACTERS

(22) 1 Control device 1.1 Transfer valve 1.2 Transfer valve 1.3 Test control valve arrangement 1.4 Precontrol valve 1.5 Safety valve, in particular safety transfer valve 1.6 Outflow valve 1.7 Non-return valve 1.8 Throttle 1.9 Throttle 1.10 Outflow valve 2 Emergency stop valve 3 Actuator 4 Turbine 5 Operating medium conducting and/or supply system 6 Control valve arrangement Ta Tank Pu Pump M Module MV1 Multiple transfer valve MV2 Multiple transfer valve MV3 Multiple transfer valve MV4 2/2-way valve MV5 2/2-way valve P Connector T Connector MMV1, MMV2, MMV3, Connectors to the multiple transfer valves MV1, MV2, MV3 MMV4, MMV5 Connectors to the 2/2-way valves MV4, MV5 X, A Connectors A2, A4, A6 Outlets on the precontrol valve Z1, Z3, Z5 Inlets on the precontrol valve