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