Steam valve device and steam turbine plant

A steam valve device configured to be attached to a steam turbine via a nozzle box, the steam valve device comprising:

• a single main steam stop valve;
• a plurality of steam regulating valves disposed on a downstream side of the main steam stop valve, each of the plurality of steam regulating valves configured to be connected to a respective one of a plurality of circumferentially arranged and partitioned sections of the nozzle box, the plurality of steam regulating valves comprising at least a first steam regulating valve adjacent to the main steam stop valve, and a second steam regulating valve adjacent to the first steam regulating valve;
• and
• an intermediate flow pipe connecting the main steam stop valve to the plurality of steam regulating valves,
• wherein the steam valve device is configured to control flow of main steam generated by a boiler to the plurality of sections of the nozzle box,
• wherein the main steam stop valve includes:
• a first casing having a first inlet portion extending in a first direction, a first outlet portion extending in a second direction perpendicular to the first direction and is connected to the intermediate flow pipe, a first flow path formed between the first inlet portion and the first outlet portion, and a first valve seat arranged in the first flow path;
• a first valve element configured to move along the second direction in the first casing and to leave and contact the first valve seat to open and close the first flow path;
• and
• a first valve rod connected to the first valve element, configured to slide along the second direction, penetrating the first casing, the first valve rod being configured to move the first valve element away from the first outlet portion to open the first flow path and to move the first valve element to the first outlet portion to close the first flow path,
• wherein each of the steam regulating valves includes:
• a second casing having a second inlet portion extending in the first direction so as to be connected to the intermediate flow pipe, a second outlet portion extending in the second direction, a second flow path formed between the second inlet portion and the second outlet portion, and a second valve seat arranged in the second flow path;
• a second valve element configured to move along the second direction in the second casing and to leave and contact the second valve seat to open and close the second flow path;
• and
• a second valve rod connected to the second valve element, configured to slide along the second direction, penetrating the second casing, the second valve rod being configured to move the second valve element away from the second outlet portion to open the second flow path and to move the second valve element to the second outlet portion to close the second flow path,
• wherein the intermediate flow pipe is configured to change a flow direction of the main steam flowing out from the first outlet portion from the second direction to the first direction to allow the main steam to flow into the second inlet portions,
• wherein the intermediate flow pipe includes:
• an intermediate flow pipe inlet portion extending in the second direction so as to communicate with the first outlet portion;
• a plurality of intermediate flow pipe outlet portions extending in the first direction at a position lower than the intermediate flow pipe inlet portion so as to communicate with the second inlet portions;
• and
• a branch portion formed between the intermediate flow pipe inlet portion and the intermediate flow pipe outlet portions so as to allow the main steam flowing through the intermediate flow pipe inlet portion to flow into the intermediate flow pipe outlet portions, the branch portion being directly connected to each of the steam regulating valves,
• wherein the main steam stop valve, the steam regulating valves, and the intermediate flow pipe are integrally formed,
• wherein in the intermediate flow pipe there are formed:
• a first flow portion defining a first flow channel and extending in the second direction to allow the main steam to flow from the intermediate flow pipe inlet portion;
• a direction changing flow portion defining a direction changing flow channel and being connected to the first flow portion so as to change the flow direction of the main steam from the second direction to the first direction;
• a second flow portion defining a second flow channel and being connected to the direction changing flow portion so as to allow the main steam flowing out from the direction changing flow portion to flow in the first direction into the branch portion;
• and
• a plurality of outlet flow paths to allow the main steam to flow from the branch portion to the plurality of intermediate flow pipe outlet portions,
• wherein, in the direction changing flow portion, a curvature radius of a center of a flow path is larger than a curvature radius of an inner circumferential side and smaller than a curvature radius of an outer circumferential side,
• wherein a center of curvature of the center of the flow path, a center of curvature of the inner circumferential side and a center of curvature of the outer circumferential side are located at different positions, and
• wherein a curvature of the outer circumferential side is smoothly connected at a predetermined curvature radius with a lower end of the first outlet portion.