Shaft-seal device for high-temperature fluid

A shaft-seal device for high-temperature fluid having a primary seal, a secondary seal, and a tertiary seal disposed at equal intervals to form a mechanical seal in a seal case installed in an apparatus housing,

• the mechanical seal exhibiting a sealing performance through a relative rotation effect between sealing end-faces that are facing end-faces of:
• rotational sealing rings fixed to a rotary shaft passing through the seal case, and
• stationary sealing rings fit and held in the seal case with O-rings in between and facing the rotational sealing rings in a displaceable manner in an axis direction of said rotary shaft, and
• seal water whose pressure is lower than a fluid pressure of an intra-apparatus housing region being circulated and supplied to each of a first sealed space formed between the primary seal and the secondary seal and a second sealed space formed between the secondary seal and the tertiary seal, wherein
• the seal case takes a metal structure comprising
• a main body portion that is a cylindrical body,
• a first holding portion that is a cylindrical body, extending from an inner-circumference edge portion of an end portion of said main body portion toward an intra-apparatus housing region direction as a single unit,
• a second holding portion that is an annular plate, extending from an end portion of the first holding portion in a radial direction inwardly as a single unit,
• a first partition portion that is an annular plate, extending from an inner-circumference end portion of the second holding portion in a radial direction inwardly as a single unit,
• a channel formation portion that is a cylindrical body extending from an inner-circumference end portion of the first partition portion in an intra-apparatus housing region direction as a single unit and forms a minute annular channel between an outer circumference surface of said rotary shaft,
• a second partition portion that is an annular plate, extending from an end portion of the channel formation portion toward a radial direction outwardly as a single unit, and
• an O-ring holding portion that is an annular plate extending from an outer-circumference end portion of the second partition portion in a radial direction outwardly as a single unit and has an outside diameter coincide with the main body portions;
• and wherein
• the seal case is fitted in the apparatus housing in a state in which first and second O-rings are interposed between inner- and outer-circumference edge portions of the O-ring holding portion and a sealing member of the apparatus housing,
• a cooling chamber is provided as an indentation formed between main body portion and the O-ring holding portion and closed by a feed and discharge path formation portion set up in the apparatus housing,
• a coolant is supplied to and discharged from the cooling chamber through feed/discharge coolant paths formed in the feed and discharge path formation portion, and
• an intra-seal case region, in which said sealing rings are provided, and a high-temperature fluid region, which is an intra-apparatus housing region, are partitioned by a cooling chamber section that is an inner-circumference section of said cooling chamber and surrounded by both partitioned sections and the channel formation portion, and
• said shaft-seal device further comprises a first water feed/discharge means for circulating and supplying the seal water to the first sealed space and a second water feed/discharge means for circulating and supplying the seal water to the second sealed space, each of which being comprised of
• a feed water path formed in the main body portion of the seal case,
• a discharge water path formed in said main body portion,
• an annular feed water channel formed in an inner-circumference surface of said main body portion and communicating with the feed water path,
• an annular discharge water channel formed on an inner-circumference surface of said main body portion and communicating with the discharge water path,
• a shower ring installed in an inner-circumference surface of said main body portion to close and seal openings of the feed/discharge water channels,
• feed water holes that are multiple through-holes communicating with a feed water channel and provided in the shower ring at equal intervals in a circumferential direction thereof, and
• discharge water holes that are multiple through-holes communicating with the discharge water channel and provided in the shower ring at equal intervals in a circumference direction thereof;
• and
• each of the first and second water feed/discharge suppresses a pulsing phenomenon of the seal water accompanying a supply and circulation in the sealed space by
• supplying the seal water supplied from the feed water path to the feed water channel to all feed water holes in the sealed space, and
• discharging the seal water in the sealed space from all discharge water holes to the discharge water path through the discharge water channel, and
• wherein in the second water feed/discharge means,
• the feed water holes are provided facing an outer-circumference surface of one of the rotational and stationary sealing rings in the tertiary seal, and
• the discharge water holes are provided facing an outer-circumference surface of another one of the rotational and stationary sealing rings in the tertiary seal.