Retractible segmented packing ring for fluid turbines having gravity springs to neutralize packing segment weight forces

An elastic fluid turbine employing a segmented seal ring to minimize leakage between rotating and stationary components, while also providing a large clearance between said components during start up and at light loads to protect said seal ring from damage, comprising:

• a stationary turbine casing encircling a rotating shaft and having an annular groove formed therein extending around said shaft, said annular groove being partially defined by a pair of opposing, spaced apart annular shoulders on said casing which form an annular opening of said groove radially into the clearance area between said casing and said shaft;
• a segmented seal ring supported by and at least partially contained in said groove, said seal ring including both upper seal segments located around the upper half of said shaft, and lower seal segments located around the lower half of said shaft, each seal segment having seal teeth;
• first spring means comprising radial springs for radially positioning said segments of said seal ring and including a compressed spring interposed between adjacent ends of said seal ring segments so that said radial springs act circumferentially to urge said ring segments to separate and move radially outward to form a larger diameter ring and thereby provide a large clearance position of said seal ring with said shaft;
• and
• second spring means comprising at least one gravity spring positioned to operate generally vertically between a lower half of said turbine casing and at least one said lower seal segment, said gravity spring means producing an upward vertical force against said lower seal segment which is substantially equal to and thereby counteracts the downward weight force of said lower seal segment;
• said large clearance position being defined such that at low speed and small turbine loads the spring forces will predominate and said segments of seal ring will be forced to said large clearance position, whereas at high flows and high working pressure, working fluid will overcome the radial spring forces and urge said seal ring segments into a small clearance position;
• whereby said gravity springs, by only neutralizing said weight forces of said lower seal segments, do not interfere with the action of said radial Springs to urge said segments out to said large clearance position at low speed and small turbine loads, and said gravity springs prevent friction and interference between adjacent said lower seal segments as they move radially inward to said small clearance position under the influence of the working fluid at high flows and high working pressure.

A seal system employing a segmented seal ring to minimize leakage between a rotating shaft and a stationary casing of an elastic fluid turbine, wherein said seal system provides a large clearance between said shaft and casing during start up and at light loads to protect said seal ring from damage, comprising:

• a segmented seal ring supported by and at least partially contained in said groove, said seal ring including both upper seal segments located around the upper half of said seal ring, and lower seal segments located around the lower half of said seal ring, each seal segment having seal teeth;
• radial springs positioned against said seal segments to urge said seal segments radially outward to form a larger diameter ring providing a large clearance position of said seal ring with said shaft, said radial springs providing forces whereby at low speed and small turbine loads the radial spring forces will predominate and said seal segments will be forced to said large clearance position, whereas at high flows and high working pressure, working fluid will overcome the radial spring forces and urge said seal segments into a small clearance position;
• and
• gravity spring means including at least one gravity spring positioned at the bottom of at least one said lower seal segment, said gravity springs positioned to operate generally vertically producing an upward vertical force against said lower seal segment which is substantially equal to and thereby counteracts the downward weight force of said lower seal segment;
• whereby said gravity springs, by only neutralizing said weight forces of said lower seal segments, do not interfere with the action of said radial springs to urge said segments out to said large clearance position at low speed and small turbine loads, and said gravity springs prevent friction and interference between said seal segments as they move radially inward to said small clearance position.