US-12624644-B2 - Seal assembly for a rotary machine

US12624644B2US 12624644 B2US12624644 B2US 12624644B2US-12624644-B2

Abstract

A rotary machine seal assembly includes seal segments configured to circumferentially extend around a rotor between a stator and the rotor of a rotary machine. One or more seal segments include a shoe plate, a seal base, and at least one intermediate member. The shoe plate is disposed along the rotor. The seal base is disposed radially outward of the shoe plate. At least one intermediate member is coupled to and disposed between the seal base and the shoe plate. The at least one intermediate member includes an actuator portion having a first coefficient of thermal expansion and a constrictor portion having a different, second coefficient of thermal expansion. The at least one intermediate member is configured to move the shoe plate from a radially outward position to a radially inward position with respect to the rotor responsive to the at least one intermediate member undergoing a temperature change.

Inventors

Rahul Anil Bidkar
Deepak Trivedi
Christopher Edward Wolfe
Darren Lee Hallman
Kristopher Frutschy
Mark Bowen

Assignees

GENERAL ELECTRIC COMPANY

Dates

Publication Date: 20260512
Application Date: 20250404

Claims (17)

1 . A rotary machine seal assembly, comprising: a packing ring formed from one or more seal segments configured to extend around a rotor between a stator and the rotor of a rotary machine, the one or more seal segments having: a seal base comprising a first hook portion and a second hook portion and defining a radially inward surface, an actuator portion; a constrictor portion; a first hook portion member positioned between the stator and the radially inward surface of the seal base at the first hook portion; and a second hook portion member positioned between the stator and the radially inward surface of the seal base at the second hook portion, wherein the actuator portion has a different coefficient of thermal expansion than the constrictor portion, wherein the actuator portion and the constrictor portion comprise a first intermediate member, the rotary machine seal assembly further comprising a second intermediate member positioned between a radially outward surface of the seal base of one of the one or more seal segments and the stator, wherein the first hook portion member is a third intermediate member disposed radially inward of the second intermediate member.
2 . The rotary machine seal assembly of claim 1 , wherein the coefficient of thermal expansion of the actuator portion is greater than the coefficient of thermal expansion of the constrictor portion.
3 . The rotary machine seal assembly of claim 1 , wherein at least one of the one or more seal segments further comprises a shoe plate.
4 . The rotary machine seal assembly of claim 3 , wherein the constrictor portion is configured to cause the actuator portion to move the shoe plate farther in a radial direction than an intermediate member formed from a single metal or a single metal alloy.
5 . The rotary machine seal assembly of claim 3 , wherein the actuator portion comprises a bellows and the constrictor portion comprises at least one wall radially extending from the seal base towards the shoe plate, and wherein the bellows comprises one or more elongated structures that are one or more of concertinaed or convoluted to form a pattern with respect to a length of the actuator portion extending in a radial direction.
6 . The rotary machine seal assembly of claim 3 , wherein the shoe plate includes one or more of an axial tooth extending in an axial direction towards a portion of the stator to form a secondary seal or one or more of a radial tooth extending in a radial direction towards a portion of the rotor to form a primary seal.
7 . The rotary machine seal assembly of claim 3 , wherein the shoe plate is configured to form a frictionless or low-friction secondary seal with a portion of the stator through a self-correcting fluid film disposed between a surface of the shoe plate and the portion of the stator.
8 . The rotary machine seal assembly of claim 1 , wherein the first hook portion is opposed to the second hook portion.
9 . The rotary machine seal assembly of claim 1 , wherein the third intermediate member is configured to urge the one or more seal segments toward a radially inward position as the rotary machine heats up.
10 . The rotary machine seal assembly of claim 9 , wherein the second hook portion member is a fourth intermediate member disposed radially inward of the second intermediate member.
11 . The rotary machine seal assembly of claim 1 , wherein the second intermediate member is configured to urge at least one of the one or more seal segments toward a radially inward position as the rotary machine heats up.
12 . The rotary seal assembly of claim 1 , wherein the constrictor portion is configured to cause the actuator portion to move a shoe plate of the one or more seal segments in a radial direction.
13 . The rotary seal assembly of claim 1 , wherein the actuator portion and the constrictor portion form a bi-material spring.
14 . The rotary seal assembly of claim 1 , wherein the constrictor portion extends from the actuator portion to the stator.
15 . The rotary machine seal assembly of claim 1 , wherein the actuator portion comprises a leaf spring.
16 . A method comprising additively manufacturing the rotary seal assembly of claim 1 .
17 . A rotary machine seal assembly, comprising: a packing ring comprising: one or more seal segments configured to extend around a rotor between a stator and the rotor of a rotary machine, wherein the one or more seal segments comprise: a seal base comprising opposed first and second hook portions and defining a radially inward surface; a first intermediate member comprising an actuator portion and a constrictor portion; a second intermediate member positioned between a radially outward surface of the seal base of one of the one or more seal segments and the stator; a third intermediate member disposed radially inward of the second intermediate member, wherein the third intermediate member is configured to urge the one or more seal segments toward a radially inward position as the rotary machine heats up; and a fourth intermediate member disposed radially inward of the second intermediate member, wherein the third intermediate member and the fourth intermediate member are positioned between the stator and the radially inward surface of the seal base at the opposed first and second hook portions of the seal base, wherein a coefficient of thermal expansion of the actuator portion differs from a coefficient of thermal expansion of the constrictor portion.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a divisional application of U.S. application Ser. No. 17/908,368 filed Aug. 31, 2022, which is a § 371 application of International Application No. PCT/US2020/025781, filed Mar. 30, 2020. Both applications are hereby incorporated by reference in their entirety. FIELD The subject matter described herein relates to seal assemblies in rotary machines. BACKGROUND Many rotary machines, such as gas turbines, steam turbines, aircraft engines, supercritical CO2 turbines, compressors and other rotary machines, have seals between the moving components (e.g., rotors) and the stationary components (e.g., stators). These seals help to reduce leakage of fluids between the rotors and stators. Increased leakage between rotors and stators can significantly reduce the power generated by the rotary machines, thereby lowering the operating efficiency of the rotary machines. Labyrinth seal assemblies, including packing rings and blade tip spill strips, are used for reducing the leakage through circumferential rotor-stator gaps from high pressure to low pressure cavities. Packing rings are assembled with a cold gap or clearance from the rotor. The radial clearance between the packing ring and the rotor varies during operation due to centrifugal growth and the relative thermal growth of the stator, the packing ring, and the rotor, prior to settling to a steady state operating clearance. The radial clearance between rotors and stators can change up to 3 millimeters on account of thermal transients and centrifugal growth. Packing rings that are assembled with small radial clearances result in seal rubs (which have increased wear and degraded leakage performance and potential rotor thermal bow), whereas packing rings assembled having large radial clearances to avoid seal rubs can lead to increased leakage. Packing rings are frequently damaged by seal rubs, leading to a need for replacement during maintenance outage cycles. Typically, packing rings are fabricated with steel and steel alloys using forging and casting operations followed by machining operations. Conventional packing rings have an inherent thermal response due to the thermal behavior, or dimensional changes in response to temperature changes, dictated by the bulk dimensions of the packing ring and the coefficient of thermal expansion of the materials used to form the packing ring, as well as those of surrounding components such as the stator and the rotary machine casing. This inherent thermal response serves as a limitation when designing, or setting the cold clearances and corresponding steady state clearances, of conventional packing rings. BRIEF DESCRIPTION In accordance with one or more embodiments described herein, a rotary machine seal assembly is provided. The rotary machine seal assembly includes seal segments configured to circumferentially extend around a rotor between a stator and the rotor of a rotary machine. One or more of the seal segments include a shoe plate, a seal base, and at least one intermediate member. The shoe plate is configured to be disposed along the rotor. The shoe plate is configured to form a primary seal with the rotor and a secondary seal with a portion of the stator. The seal base is configured to be disposed radially outward of the shoe plate. At least one intermediate member is coupled to and disposed between the seal base and the shoe plate. The at least one intermediate member includes an actuator portion having a first coefficient of thermal expansion and a constrictor portion having a different, second coefficient of thermal expansion. The at least one intermediate member is configured to move the shoe plate from a radially outward position to a radially inward position with respect to the rotor responsive to the at least one intermediate member undergoing a temperature change. Optionally, the first coefficient of thermal expansion of the actuator portion is greater than the second coefficient of thermal expansion of the constrictor portion. Optionally, the constrictor portion is configured to cause the actuator portion to move the shoe plate farther in a radial direction than an intermediate member formed from a single metal or a single metal alloy. Optionally, the actuator portion includes a bellows and the constrictor portion includes at least one wall radially extending from the seal base toward the shoe plate. Optionally, the bellows includes one or more elongated structures that are one or more of concertinaed or convoluted to form a pattern along a length of the actuator portion extending in a radial direction. Optionally, the actuator portion and the constrictor portion form a leaf spring. Optionally, the at least one intermediate member includes a second intermediate member positioned between a radially outward surface of the seal base and the stator. Optionally, the at least one intermediate member includes a third intermediate member and a fourth intermediate