Turbomachine labyrinth seal design for oxygen rich process fluids

Abstract

A gas seal to seal an oxygen-rich process gas within a compressor or expander, including a rotor component having a rotating element and a stator component having a stationary element. Wherein at least a portion of the rotating element includes the teeth of a first labyrinth seal. Wherein the first labyrinth seal is part of a first sealing zone. Wherein at least a portion of the stationary element includes the teeth of a second labyrinth seal. Wherein the second labyrinth seal is part of a second sealing zone.

Claims

1. A gas seal to seal an oxygen-rich process gas within a compressor or expander, the comprising: a rotor component comprising a rotating element, wherein at least a first rotating portion of the rotating element has no labyrinth seal teeth, wherein at least a second rotating portion of the rotating element comprises a rotor insert, wherein the rotor insert comprises labyrinth seal teeth, a stator component comprising a stationary element, wherein at least a first stationary portion of the stationary element comprises labyrinth seal teeth, wherein at least a second stationary portion of the stationary element has no labyrinth seal teeth, wherein the first rotating portion and the first stationary portion comprise a first sealing zone, wherein the second rotating portion and the second stationary portion comprise a second sealing zone.

2. The gas seal of claim 1, wherein the rotating element and the stationary element are made of different materials.

3. The gas seal of claim 1, wherein the first sealing zone comprises material selected from the group consisting of brass, copper-nickel alloys, Inconel, Elgiloy, and polytetrafluoroethylene (Teflon).

4. The gas seal of claim 1, wherein the second sealing zone comprises material selected from the group consisting of aluminum, stainless steel, and carbon steel.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) For a further understanding of the nature and objects for the present invention, reference should be made to the following detailed description, taken in conjunction with the accompanying drawings, in which like elements are given the same or analogous reference numbers and wherein:

(2) FIG. 1 is a schematic representation of one embodiment of a labyrinth seal as known in the art.

(3) FIG. 2 is another schematic representation of one embodiment of a labyrinth seal as known in the art.

(4) FIG. 3 is another schematic representation of one embodiment of a labyrinth seal as known in the art.

(5) FIG. 4 is another schematic representation of one embodiment of a labyrinth seal as known in the art.

(6) FIG. 5 is another schematic representation of one embodiment of a labyrinth seal as known in the art.

(7) FIG. 6 is a schematic representation of a labyrinth seal according to one embodiment of the present invention.

(8) FIG. 7 is a schematic representation of a labyrinth seal according to one embodiment of the present invention.

(9) FIG. 8 is a schematic representation of a labyrinth seal according to one embodiment of the present invention.

ELEMENT NUMBERS

(10) 101=labyrinth seal 102=high-pressure region 103=low-pressure region 104=cavities 105=teeth 106=rotor 107=torturous gas path 108=stator 601=labyrinth seal 602=high-pressure region 603=low-pressure region 604=cavities 605a=stator teeth 605b=rotor teeth 606a=rotor 606b=rotor insert 608a=first stator segment 608b=second stator segment 608c=third stator segment 608d=fourth stator segment 609=inlet seal gas stream 609a=first portion of seal gas stream 609b=second portion of seal gas stream 609c=outlet seal gas stream 610=inlet buffer gas stream 610a=first portion of buffer gas stream 610b=second portion of buffer gas stream 610c=outlet buffer gas stream 611=combined gas outlet stream 701=first sealing zone 702=second sealing zone

DESCRIPTION OF PREFERRED EMBODIMENTS

(11) Illustrative embodiments of the invention are described below. While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

(12) It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developer's specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

(13) As used herein, the term rotor is defined as the rotating part of the machine.

(14) As used herein, the term stator is defined as the non-moving, fixed part of the machine.

(15) As used herein, the term labyrinth seal is defined as a type of mechanical seal that provides a torturous path to help prevent leakage.

(16) As used herein, the term labyrinth teeth is defined as a number of sharp-edged flow restrictors.

(17) As used herein, the term oxygen rich is defined as a gas stream with greater than 23.5% oxygen by mass.

(18) A new and unforeseen arrangement is proposed which simultaneously employs both teeth on rotor and teeth on stator for a robust mechanical design with enriched oxygen fluid. Wherein, the labyrinth system comprises an oxygen rich zone and a non-oxygen rich zone. In the oxygen rich zone labyrinth teeth are present on the stator in exempt (nonflammable) material. In the non-oxygen rich zone, the labyrinth teeth are present on the rotor comprising a material which is more flammable than the teeth used in the oxygen rich zone.

(19) Turning to FIG. 6, one embodiment of the present invention is presented. The gas seal as described in the present invention may be used at cryogenic temperatures, or may be used at ambient or warm temperatures. It is noted that spacing (clearance gap) G1 and G2 are exaggerated for clarity. Stator 608 comprises at least four components, 608a, 608b, 608c, and 608d. Toothed components 608a and 608b have labyrinth teeth 605a. Stator components 608c and 608d do not have labyrinth teeth. One or more of stator components 608a, 608b, 608c, and 608d may be made of any appropriate material known to one of ordinary skill in the art. One or more of stator components 608a, 608b, 608c, and 608d may be made of any appropriate material known to one of ordinary skill in the art. One or more of stator components 608a, 608b, 608c, and 608d may be made of brass.

(20) Rotor 606 comprises at least two components, 606a and 606b. Rotor component 606a does not have labyrinth teeth. Rotor component 606b has labyrinth teeth 605b. Rotor component 606b is rigidly, but removably attached to rotor component 606a. Rotor component 606b may be press-fit to rotor component 606a. Rotor components 606a and 606b may be made of any appropriate material known to one of ordinary skill in the art. Rotor components 606a and 606b may be made of any appropriate material known to one of ordinary skill in the art. Rotor components 606a and 606b may be made of stainless steel.

(21) As indicated in FIG. 7, Toothed components 608a and 608b and rotor component 606a are part of first sealing zone 701. Stator components 608c and 608d and toothed rotor component 606b are part of second sealing zone 701. First sealing zone 701 is configured to be safe and compatible with oxygen-rich fluids. Appropriate materials for first sealing zone 701 include brass, copper-nickel alloys, Elgiloy, and polytetrafluoroethylene. The specific compatible material may be used on any individual component or a combination of one or more components. Multiple compatible materials may be used in the overall component. First sealing zone 701 is preferably made of brass. Second sealing zone 702 is not configured to necessarily be compatible with oxygen-rich fluids. Appropriate materials for second sealing zone 702 include aluminum, stainless steel, and carbon steel. Second sealing zone 702 is preferably made of stainless steel.

(22) Turning to FIG. 8, the flow of seal gas stream 609 and buffer gas stream 610 is illustrated. Seal gas stream 609 may be any appropriate gas known to one of ordinary skill in the art. Seal gas stream 609 may be nitrogen. Seal gas stream 609 enters through a channel between toothed stator components 608a and 608b. A first portion, seal gas stream 609a, then passes through clearance gap G1, and thus in between toothed stator component 608a and rotor component 606a, thus providing a portion of the component sealing. Seal gas stream 609c then exits the system. As seal gas stream 609c exits the system, it has become blended with at least a part of the fluid that is being compressed.

(23) A second portion, seal gas stream 609b, then passes through gap G1, and thus in between toothed stator component 608b and rotor component 606a, thus providing another portion of the component sealing. Seal gas stream 609b then combines with exiting buffer gas stream 610a, discussed below, and exits the system. This portion of labyrinth seal 601 is potentially exposed to highly oxygen-enriched process gas, and thus the toothed components are made of brass and oxygen-safe seal gas streams are utilized.

(24) Buffer gas stream 610 may be any appropriate gas known to one of ordinary skill in the art. Buffer gas stream 610 may be nitrogen. Seal gas stream 609 enters through a channel between stator components 608c and 608d. A first portion, buffer gas stream 610a, then passes through gap G2, and thus in between stator component 608c and toothed rotor component 606b, thus providing another portion of the component sealing. Seal gas stream 610a combines with exiting seal gas stream 609b, thus forming combined outlet gas outlet stream 611, which then exits the system.

(25) A second portion, buffer gas stream 610b, then passes through clearance gap G2, and thus in between stator component 608d and toothed rotor component 606b, thus providing another portion of the component sealing. Buffer gas stream 610c then exits the system. This portion of labyrinth seal 601 is potentially unexposed to highly oxygen-enriched process gas, and thus the toothed components are made of stainless steel and oxygen-safe seal gas streams is not required.

(26) It will be understood that many additional changes in the details, materials, steps and arrangement of parts, which have been herein described in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims. Thus, the present invention is not intended to be limited to the specific embodiments in the examples given above.