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US-20260126116-A1 - MECHANICAL SEAL AND COOLING STATE ESTIMATION METHOD

US20260126116A1US 20260126116 A1US20260126116 A1US 20260126116A1US-20260126116-A1

Abstract

A mechanical seal includes: a rotary side unit provided on a rotary shaft so as to be rotatable therewith and having a rotary sealing ring; and a stationary side unit provided on a casing surrounding the rotary shaft and having a stationary sealing ring on which the rotary sealing ring slides to seal a sealing target fluid in an inside region in the casing. Sliding portions of the rotary sealing ring and the stationary sealing ring are cooled by a flushing fluid. The mechanical seal includes a temperature difference detection part provided in the stationary side unit and configured to detect a temperature difference between a temperature of a first flushing fluid that is the flushing fluid before cooling the sliding portions and a temperature of a second flushing fluid that is the flushing fluid after cooling the sliding portions.

Inventors

  • Koki Fukui
  • Kazuma Adachi

Assignees

  • PILLAR CORPORATION

Dates

Publication Date
20260507
Application Date
20221116

Claims (6)

  1. 1 . A mechanical seal including: a rotary side unit provided on a rotary shaft so as to be rotatable therewith and having a rotary sealing ring; and a stationary side unit provided on a casing surrounding the rotary shaft and having a stationary sealing ring on which the rotary sealing ring slides to seal a sealing target fluid in an inside region in the casing, sliding portions of the rotary sealing ring and the stationary sealing ring being cooled by a flushing fluid, the mechanical seal comprising a temperature difference detection part provided in the stationary side unit and configured to detect a temperature difference between a temperature of a first flushing fluid that is the flushing fluid before cooling the sliding portions and a temperature of a second flushing fluid that is the flushing fluid after cooling the sliding portions.
  2. 2 . The mechanical seal according to claim 1 , further comprising a control part configured to calculate a coefficient of kinetic friction of the sliding portions, based on the temperature difference.
  3. 3 . The mechanical seal according to claim 1 , wherein the temperature difference detection part is a thermocouple having a reference contact and a temperature measuring contact, the reference contact is placed so as to be in contact with one of the first flushing fluid and the second flushing fluid, and the temperature measuring contact is placed so as to be in contact with the other of the first flushing fluid and the second flushing fluid.
  4. 4 . A cooling state estimation method for, in a mechanical seal including: a rotary side unit provided on a rotary shaft so as to be rotatable therewith and having a rotary sealing ring; and a stationary side unit provided on a casing surrounding the rotary shaft and having a stationary sealing ring on which the rotary sealing ring slides to seal a sealing target fluid in an inside region in the casing, estimating a cooling state of sliding portions of the rotary sealing ring and the stationary sealing ring by a flushing fluid, the cooling state estimation method comprising a step of detecting, by a temperature difference detection part, a temperature difference between a temperature of the flushing fluid before cooling the sliding portions and a temperature of the flushing fluid after cooling the sliding portions.
  5. 5 . The cooling state estimation method according to claim 4 , further comprising a step of calculating a coefficient of kinetic friction of the sliding portions, based on the detected temperature difference.
  6. 6 . The cooling state estimation method according to claim 5 , further comprising a step of estimating the cooling state of the sliding portions, based on the calculated coefficient of kinetic friction and a characteristic curve showing behavior of the coefficient of kinetic friction with respect to a dimensionless coefficient for lubrication characteristics of the sliding portions.

Description

TECHNICAL FIELD The present invention relates to a mechanical seal and a cooling state estimation method. BACKGROUND ART As a seal for sealing a sealing target fluid inside a rotary machine, for example, a mechanical seal described in PATENT LITERATURE 1 is known. The mechanical seal of PATENT LITERATURE 1 includes a rotary sealing ring (rotary ring) provided on a rotary shaft of a rotary machine so as to slide on a stationary sealing ring, and the stationary sealing ring (fixed ring) provided on a housing of the rotary machine. The sliding portions of the rotary sealing ring and the stationary sealing ring are cooled and lubricated by a flushing fluid. CITATION LIST Patent Literature PATENT LITERATURE 1: Japanese Laid-Open Patent Publication No. 2021-060079 SUMMARY OF THE INVENTION Technical Problem In the mechanical seal of PATENT LITERATURE 1, in order to grasp whether or not the sliding portions of the rotary sealing ring and the stationary sealing ring are appropriately cooled by the flushing fluid, it is necessary to disassemble the mechanical seal and visually and directly observe the sliding portions. Therefore, it is difficult to grasp the cooling state of the sliding portions while the mechanical seal is in operation. The present disclosure has been made in view of such circumstances, and an object of the present disclosure is to provide a mechanical seal and a cooling state estimation method that enable estimation of a cooling state of sliding portions of a rotary sealing ring and a stationary sealing ring by a flushing fluid without directly observing the sliding portions. Solution to Problem (1) The present disclosure is directed to a mechanical seal including: a rotary side unit provided on a rotary shaft so as to be rotatable therewith and having a rotary sealing ring; and a stationary side unit provided on a casing surrounding the rotary shaft and having a stationary sealing ring on which the rotary sealing ring slides to seal a sealing target fluid in an inside region in the casing, sliding portions of the rotary sealing ring and the stationary sealing ring being cooled by a flushing fluid, the mechanical seal including a temperature difference detection part provided in the stationary side unit and configured to detect a temperature difference between a temperature of a first flushing fluid that is the flushing fluid before cooling the sliding portions and a temperature of a second flushing fluid that is the flushing fluid after cooling the sliding portions. In the mechanical seal of the present disclosure, the temperature difference between the temperature of the first flushing fluid before cooling and the temperature of the second flushing fluid after cooling is detected by the temperature difference detection part. If the temperature difference is relatively large, the heat generation at the sliding portions is increased due to frictional heat, etc., so that the cooling state of the sliding portions can be roughly estimated to be a state where the amount of the flushing fluid supplied to the sliding portions is insufficient. If the temperature difference is relatively small, the heat generation at the sliding portions is reduced to be low, so that the cooling state of the sliding portions can be roughly estimated to be a state where the sliding portions are appropriately cooled by the flushing fluid. Therefore, by detecting the temperature difference by the temperature difference detection part, the cooling state of the sliding portions by the flushing fluid can be estimated without directly observing the sliding portions of the rotary sealing ring and the stationary sealing ring. (2) Preferably, the mechanical seal of (1) above further includes a control part configured to calculate a coefficient of kinetic friction of the sliding portions, based on the temperature difference. In this case, since the coefficient of kinetic friction calculated by the control part is closely related to the cooling state of the sliding portions, the cooling state of the sliding portions of the rotary sealing ring and the stationary sealing ring by the flushing fluid can be more accurately estimated from the coefficient of kinetic friction. (3) In the mechanical seal of (1) or (2) above, preferably, the temperature difference detection part is a thermocouple having a reference contact and a temperature measuring contact, the reference contact is placed so as to be in contact with one of the first flushing fluid and the second flushing fluid, and the temperature measuring contact is placed so as to be in contact with the other of the first flushing fluid and the second flushing fluid. In this case, the temperature difference between the reference contact and the temperature measuring contact of the thermocouple is the temperature difference between the temperature of the first flushing fluid before cooling and the temperature of the second flushing fluid after cooling. Therefore, by using the thermocouple,