DRY GAS SEAL

• US 20180266265A1
• Filed: 03/15/2018
• Published: 09/20/2018
• Est. Priority Date: 03/17/2017
• Status: Active Grant

• Current Assignee: Nuovo Pignone Tecnologie SRL (Nuovo Pignone International SRL)
• Original Assignee: Nuovo Pignone Tecnologie SRL (Nuovo Pignone International SRL)
• Inventors: GERBI, Filippo, RIZZO, Emanuele, BERNOCCHI, Andrea, MARRAZZO, Marco, BALDASSARRE, Leonardo, RICCHIUTI, Amelia Lavinia
• Granted Patent: US 10,738,641 B2
• Time in Patent Office: Days
• CPC Class Codes: F01D 11/003 by packing rings; Mechanical seals
• CPC Class Codes: F01D 11/06 Control thereof
• CPC Class Codes: F01D 21/003 Arrangements for testing or measuring for measuring vibrations G01H
• CPC Class Codes: F02C 7/28 Arrangement of seals
• CPC Class Codes: F04D 29/104 the sealing fluid being other than the working fluid or being the working fluid treated
• CPC Class Codes: F04D 29/124 with special means for adducting cooling or sealing fluid
• CPC Class Codes: F05D 2240/55 Seals
• CPC Class Codes: F05D 2260/80 Diagnostics
• CPC Class Codes: F05D 2270/305 Tolerances
• CPC Class Codes: F05D 2270/331 Mechanical loads
• CPC Class Codes: F05D 2270/334 Vibration measurements
• CPC Class Codes: F05D 2270/808 Strain gauges; Load cells
• CPC Class Codes: F16J 15/26 with stuffing-boxes for rigid sealing rings
• CPC Class Codes: F16J 15/3492 with monitoring or measuring means associated with the seal
• CPC Class Codes: F16J 15/40 by means of fluid

Abstract

A dry gas seal for sealing the shaft of a turbomachinery, provided with means for the continuous health monitoring of the dry gas seal comprising one or more sensors adapted to measure strains and/or loads induced to the primary ring of the dry gas seal and/or strains induced to one or more of the elastic elements coupled to the primary ring and/or adapted to measure displacements of the primary ring or of an element coupled to the primary ring, for an early detection of failure of the seal, thus enabling main failures early detection capability and proactive maintenance actions.

Claims

1. A dry gas seal for sealing the shaft of a turbomachinery, the seal comprising:

a mating ring configured to be coupled to the shaft of the turbomachinery to rotate at shaft rotational speed;

a primary ring that seals against the mating ring, the primary ring configured to be anti-rotationally coupled to a static part of the turbomachinery; and

one or more elastic elements preloaded to push the primary ring against the mating ring,

wherein one or more sensors are provided, said one or more sensors being adapted to measure strains and/or loads induced to the primary ring and/or to one or more of the elastic elements and/or displacements of the primary ring or of an element coupled to the primary ring for an early detection of failure of the seal.

2. The seal according to claim 1, wherein the primary ring is configured to be anti-rotationally coupled with a retainer through an anti-rotational system comprising one or more anti-rotational pin or lug, the sensors comprising a load sensor coupled to one or more of such anti-rotational pin or lug to detect torques induced to the primary ring.

3. The seal according to claim 1, wherein sensors comprise an axial vibration sensor to detect axial movements of the primary ring and/or the retainer towards/from the mating ring.

4. The seal according to claim 1, wherein the elastic element or elements are coupled to the primary ring through an intermediate element capable of axial movement to move with the primary ring upon mating ring axial movement, the sensors comprising a displacement sensor to detect axial movement of the intermediate element.

5. The seal according to claim 4, wherein the sensors comprise axial vibration sensors or load sensors coupled to, or integrated in, one or more of the elastic elements.

6. The seal according to claim 1, wherein the seal comprises a flowpath for a sealing gas to flow from an inlet to an outlet to cause the lift-off of the mating ring and the primary ring, a flow sensor being provided in such flowpath to measure the flow of the sealing gas.

7. A turbomachine comprising:

a rotor assembly including at least an impeller;

a bearing connected to, and for rotatably supporting, the rotor assembly;

a stator; and

a sealing mechanism disposed between the rotor assembly and the bearing, said sealing mechanism including a dry gas seal according to claim 1 with the mating ring and the primary ring of the seal respectively coupled to the rotor assembly and the stator.

8. The turbomachine according to claim 7, wherein the primary ring of the seal is coupled to a retainer through an anti-rotational system comprising one or more anti-rotational pin or lug and an intermediate element or carrier acting as a pusher sleeve to axially push the primary ring against the mating ring under the action of a preloaded elastic element, the sensor or sensors of the seal comprising one or more sensors belonging to the group consisting in:

displacement sensor for the measurement of the axial displacement of the primary ring, displacement sensor for the measurement of the axial displacement of the intermediate ring, strain sensor for the measurement of the torque induced to the primary ring, load sensors for the measurement of static load acting on the carrier and/or the primary ring, load sensors for the measurement of vibrations of the carrier and/or the primary ring.

9. The turbomachine according to one or more of claim 7, further comprising a control unit configured to:

read the output of the sensor or the sensors;

compare the output with thresholds to determine a fault condition of the seal; and

provide an alarm indication.

10. The turbomachine according to claim 9, wherein the control unit is further configured to shut down the turbomachine if the output of the sensors are indicative of a severe fault condition of the seal.

14. A system for the monitoring and early detection of fault of dry gas seals of remotely located turbomachines, the system comprising:

a collecting unit for collecting data from sensors of the dry seals of the turbomachines according to claim 1;

communication units configured to interface the turbomachines to the collecting unit; and

a software platform configured to read data from the collecting unit to perform analytics to do early detection and/or send notifications of potential damages or to perform condition based maintenance of the turbomachines.

11. A method for monitoring the status of a dry gas seal in a turbomachine, the method comprising the operations of:

providing sensors to measure strains/loads induced to the primary ring and/or displacements of the primary ring or of an element coupled to the primary ring of the dry gas seal;

setting acceptance criteria for the values measured by the sensors;

reading the output of the sensors;

testing the output with the acceptance criteria; and

activating an alarm and/or shutting down the turbomachine if one or more values measured by the sensors do not follow the acceptance criteria.

12. The method according to claim 11, further comprising:

sending the output of the sensors to a remote software platform capable to collect data from seals of different turbomachine to perform analytics to do early detection.

13. The method according to claim 12, further comprising sending notifications of potential damages or to perform condition based maintenance.