Articulated snout rings having spaced teeth

• US 5,433,453 A
• Filed: 03/02/1994
• Issued: 07/18/1995
• Est. Priority Date: 03/02/1994
• Status: Expired due to Fees

• Current Assignee: Demag Delaval Turbomachinery Corporation Turbocare Division
• Original Assignee: IMO Industries Incorporated Quabbin Division
• Inventors: Dalton, William S.
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): CUMMINGS, SCOTT
• Application Number:
  US08/204,959
• Time in Patent Office: 503 Days
• Field of Search: 277/26, 277/174, 277/175, 277/193, 277/208, 277/214, 277/215, 277/236, 415/134, 415/135, 415/136
• US Class Current: 277/606
• CPC Class Codes: F01D 11/005 Sealing means between non relatively rotating elements
• CPC Class Codes: F16J 15/164 the sealing action depending on movements; pressure difference, temperature or presence of leaking fluid

Abstract

In a turbine inclusive of: a turbine shaft having a longitudinal axis, a steam pipe, a casing circumadjacent the pipe, the pipe and casing being shiftable in vertical and transverse and axial directions relative to the longitudinal axis of the shaft, and a seal assembly disposed between the pipe and casing and comprising a stack of interdigitated relatively large and small piston rings, each large ring loosely fitting inside the shell during nonoperative conditions and having teeth firmly and sealingly engaging the casing during operative conditions; and having a coefficient of thermal expansion greater than that of the casing for expanding at a rate faster than the expansion rate of the casing under a condition of increased temperature, each small ring loosely fitting around the pipe during nonoperative conditions and having teeth firmly and sealingly engaging the pipe during operative conditions; and having a coefficient of thermal expansion less than that of the pipe for expanding at a rate slower than the expansion rate of the pipe under a condition of increased temperature, with the large and small rings tightening upon the respective casing and pipe respectively under an increasing temperature condition and shrinking from the respective shell and pipe respectively under a decreasing temperature condition, and the teeth of the rings deforming to create a complete seal.

Claims

1. In a turbine inclusive of:

a turbine shaft having a longitudinal axis,

a steam pipe,

a casing circumadjacent the pipe,

the pipe and casing being shiftable in vertical and transverse and axial directions relative to the longitudinal axis of the shaft,

and a seal assembly disposed between the pipe and casing and comprising a stack of interdigitated relatively large and small piston rings,

the improvement comprising;

each large ring

(a) loosely fitting inside the shell during nonoperative conditions and having a plurality of spaced teeth firmly and sealingly engaging the casing during operative conditions; and

(b) having a coefficient of thermal expansion greater than that of the shell for expanding at a rate faster than the expansion rate of the shell under a condition of increased temperature,

each small ring

(a) loosely fitting around the pipe during nonoperative conditions and having a plurality of spaced teeth firmly and sealingly engaging the pipe during operative conditions; and

(b) having a coefficient of thermal expansion less than that of the pipe for expanding at a rate slower than the expansion rate of the pipe under a condition of increased temperature, with the large and small rings tightening upon the respective casing and pipe respectively under a decreasing temperature condition due to the relative coefficients of thermal expansion between the large and small rings and the respective casing and pipe, and the teeth of the rings deforming to provide a positive seal without the danger of cracking either the casing or pipe.

2. In a turbine as set forth in claim 1, wherein the piston rings are fabricated from stainless steel.

3. In a turbine as set forth in claim 1, wherein the teeth on the large and small piston rings are angularly upwardly inclined.

4. In a turbine as set forth in claim 1, the further improvement of a surface coating of a thin layer of chrome carbide on the mating faces of the large and small piston rings.