Steam valve and steam turbine system

1. A steam valve, comprising:

a valve casing having a valve chest, an inlet flow passage having an opening into the valve chest, an outlet flow passage having an opening into the valve chest, and a valve seat surrounding the opening of the outlet flow passage;

a first valve body housed in the valve chest and capable of making contact with the valve seat in a vertical direction;

a second valve body housed in the valve chest coaxially with the first valve body and capable of making contact with the valve seat in the vertical direction;

a second valve rod inserted through an upper section of the valve casing in the vertical direction and extending from the second valve body to an outside of the valve casing;

a first valve rod inserted through an inside of the second valve rod and extending from the first valve body to the outside of the valve casing;

a first actuator disposed outside the valve casing and capable of applying a first biasing force in the vertical direction to the first valve rod;

a second actuator disposed outside the valve casing and capable of applying a second biasing force in the vertical direction to the second valve rod;

a first link mechanism disposed between the first actuator and the first valve rod and capable of transmitting the first biasing force;

a second link mechanism disposed between the second actuator and the second valve rod and capable of transmitting the second biasing force, the second link mechanism having a linking part provided integrally with the second valve rod and a lever which is pin-coupled to the linking part; and

a guide mechanism capable of regulating horizontal displacement of the linking part when the linking part moves in the vertical direction in response to tilting of the lever,

wherein the guide mechanism includes:

a support frame disposed above the valve casing;

a pair of guide plates each extending in the vertical direction, and holding the linking part from both sides in a horizontal direction; and

a pair of support portions each fixed to the support frame, and supporting the pair of guide plates respectively.

2. The steam valve according to claim 1 , wherein the linking part has curved surfaces in regions facing the guide plates.

3. The steam valve according to claim 1 , wherein the linking part includes inclined surfaces on an upper side and a lower side of regions facing the guide plates.

4. The steam valve according to claim 1 ,

wherein one of the linking part or each guide plate has a groove extending in the vertical direction, and

wherein the other one of the linking part or each guide plate has a protrusion which is in engagement with the groove so as to be slidable in the groove.

5. The steam valve according to claim 1 , wherein one of the linking part or each guide plate has a surface comprising a heat-resistant resin in a region facing the other one of the linking part or each guide plate.

6. A steam valve comprising:

a valve casing having a valve chest, an inlet flow passage having an opening into the valve chest, an outlet flow passage having an opening into the valve chest, and a valve seat surrounding the opening of the outlet flow passage;

a first valve body housed in the valve chest and capable of making contact with the valve seat in a vertical direction;

a second valve body housed in the valve chest coaxially with the first valve body and capable of making contact with the valve seat in the vertical direction;

a second valve rod inserted through an upper section of the valve casing in the vertical direction and extending from the second valve body to an outside of the valve casing;

a first valve rod inserted through an inside of the second valve rod and extending from the first valve body to the outside of the valve casing;

a first actuator disposed outside the valve casing and capable of applying a first biasing force in the vertical direction to the first valve rod;

a second actuator disposed outside the valve casing and capable of applying a second biasing force in the vertical direction to the second valve rod;

a first link mechanism disposed between the first actuator and the first valve rod and capable of transmitting the first biasing force;

a second link mechanism disposed between the second actuator and the second valve rod and capable of transmitting the second biasing force, the second link mechanism having a linking part provided integrally with the second valve rod and a lever which is pin-coupled to the linking part; and

a guide mechanism capable of regulating horizontal displacement of the linking part when the linking part moves in the vertical direction in response to tilting of the lever,

wherein the guide mechanism includes:

a support frame disposed above the valve casing;

a guide cylinder interposed between the first valve rod and the linking part; and

a support portion fixed to the support frame and supporting the guide cylinder.

7. The steam valve according to claim 6 , wherein the guide cylinder has a curved surface in a lower-end side region facing the linking part.

8. The steam valve according to claim 6 , wherein the guide cylinder has a tapered surface in a lower-end side region facing the linking part.

9. The steam valve according to claim 6 ,

wherein one of the linking part or the guide cylinder has a groove extending in the vertical direction, and

wherein the other one of the linking part or the guide cylinder has a protrusion in engagement with the groove so as to be slidable in the groove.

10. The steam valve according to claim 6 , wherein one of the linking part or the guide cylinder has a surface comprising a heat-resistant resin in a region facing the other one of the linking part or the guide cylinder.

11. A steam turbine system, comprising:

the steam valve according to claim 1 ; and

a steam turbine configured to be supplied with steam from the steam valve.

12. A steam turbine system, comprising:

the steam valve according to claim 6 ; and

a steam turbine configured to be supplied with steam from the steam valve.