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CN-122003557-A - Method for determining the state of a mechanical seal

CN122003557ACN 122003557 ACN122003557 ACN 122003557ACN-122003557-A

Abstract

The invention relates to a method for determining the state of a mechanical seal on the basis of a layered model structure, comprising the method steps of a) detecting at least one operating parameter that characterizes the operating conditions of the mechanical seal, b) predicting the heat source and/or leakage and/or temperature in the contact area of the mechanical seal using a plurality of models, in particular a tribological model of the mechanical seal with the detected operating parameter as input parameter and/or one or more tribological properties of the mechanical seal, and a thermal fluid and/or thermal model of the thermal-related peripheral device, c.dynamically reconstructing the contact state of the mechanical seal and/or the temperature characteristic curve in the sealing contact using the predicted heat source and/or leakage and the temperature T_mate measured at a component of the mechanical seal.

Inventors

  • C. Bruce's
  • B. Janjik
  • M. Corano

Assignees

  • KSB股份有限公司

Dates

Publication Date
20260508
Application Date
20241007
Priority Date
20231012

Claims (15)

  1. 1. A method for determining the state of a mechanical seal based on a layered model structure, having the following method steps: a. Detecting at least one operating parameter indicative of an operating condition of the mechanical seal; b. Predicting heat sources and/or leaks and/or temperatures in the contact area of the mechanical seal using a plurality of models, in particular a tribological model of the mechanical seal with the detected operating parameters as input variables and/or one or more tribological properties of the mechanical seal, and a thermal fluid and/or thermal structure model of the mechanical seal together with thermally relevant peripherals; c. In the case of the application of a thermal fluid and/or thermal structure model of the mechanical seal, the contact state of the mechanical seal and/or the temperature characteristic curve in the seal contact is dynamically reconstructed using the predicted heat source and/or leakage and the temperature t_mate measured at one component of the mechanical seal.
  2. 2. Method according to claim 1, characterized in that the operating parameters characterizing the external conditions of the mechanical seal comprise the working fluid pressure in the region of the mechanical seal and/or the rotational speed of the shaft and/or the temperature of the working fluid in the vicinity of the mechanical seal.
  3. 3. A method according to any of the preceding claims, characterized in that the tribological model predicts heat sources and/or leaks and/or temperatures as a function of operating parameters for a given heat transfer coefficient at the wetted ring surface.
  4. 4. Method according to any of the preceding claims, characterized in that as tribological properties the surface properties of the contact surface of the mechanical seal are incorporated into the tribological model, wherein the surface properties comprise, for example, characteristic data about the shape tolerance and/or the surface roughness of the mating surface.
  5. 5. A method according to any of the preceding claims, characterized in that the heat transfer coefficient is determined by a thermal fluid and/or a thermal structural model providing realistic boundary conditions of the mechanical seal.
  6. 6. Method according to claim 5, characterized in that a determined heat transfer coefficient is provided at the tribological model in order to simulate an updated heat source based on a new heat transfer coefficient, wherein the iteration is preferably repeated until the change of the heat source no longer exceeds a limit value.
  7. 7. Method according to any of the preceding claims, characterized in that a transfer function between the heat source and the t_mate can be identified based on the thermal fluid and the thermal structure model, in particular in the form of a first or second order hysteresis.
  8. 8. The method according to claim 7, characterized in that for reconstructing the contact state an inverse transfer function is estimated.
  9. 9. Method according to any of the preceding claims, characterized in that a meta model is provided, which performs an evaluation of the state of the mechanical seal based on the time signal of the measured temperature t_mate and the reconstructed contact state.
  10. 10. The method according to claim 7, characterized in that statistical and/or machine learning methods are used for the evaluation.
  11. 11. Method according to any of the preceding claims, characterized in that an analysis of the measured temperature characteristic curve t_mate is performed by the meta model, in particular determining the characteristics of the occurring temperature rises, such as the number of temporary temperature rises and/or the shape of the temporary temperature rises and/or the frequency of the occurring temporary temperature rises and/or the time intervals between the occurring temporary temperature rises.
  12. 12. Method according to any of the preceding claims, characterized in that the meta model relates the determined characteristics of the occurring temperature rise to the average temperature of the measured temperature t_mate and/or further detected operating parameters, such as the fluid pressure in the area of the mechanical seal and/or the rotational speed of the shaft.
  13. 13. Method according to any of the preceding claims 7 to 10, characterized in that the meta model makes a life estimation of the mechanical seal.
  14. 14. A monitoring unit for a mechanical seal configured to perform the method according to any of the preceding claims.
  15. 15. A pump having a monitoring unit according to claim 12.

Description

Method for determining the state of a mechanical seal Technical Field The present invention relates to a method for determining the state of a mechanical seal (or slip ring seal Gleitringdichtung). Background A mechanical seal is installed in particular in the pump and serves to seal the rotating pump shaft against the housing. The main components of the mechanical seal are two mutually sliding members, a rotating ring (or called a moving ring, GLEITRING) fastened in torsion at the shaft and a stationary ring (or called a stationary ring, GEGENRING) fixed at the housing. The facing sliding surface between the two parts (depending on the type of mechanical seal) is mostly flat and is typically composed of carbon-graphite material, metal, ceramic, plastic or resin bonded carbon. The distance of the sliding surfaces from each other is called the seal gap. The function, lifetime and reliability of a mechanical seal are mainly dependent on the conditions (state) in the sealing contact. The estimation and monitoring of this state enables an explanation of the remaining life of the seal and thus forms the basis for preventive maintenance. In-situ measurement of the state in the sealing contact is only possible in the laboratory with great measuring effort, but is hardly possible in field operation. Therefore, measurements, such as temperature measurements, must be made at adjacent surfaces/elements/components of the mechanical seal. For example, the temperature measurement can be carried out outside the sealing contact, at or in a stationary ring of the seal, for example as described in the as yet unpublished german patent application 102023109020.8. The relation between the measured temperature outside the sealing contact and the contact state depends inter alia on the thermal environmental conditions of the sealing ring. The estimation of the contact state, in particular of the thermal state, is only carried out if the thermal environmental conditions, in particular the heat transfer process around the sealing ring, are known and can be taken into account when analyzing and interpreting the measured temperature characteristic curve. Furthermore, the dependency of the heat source in the contact on the operating parameters has to be determined. Disclosure of Invention A solution is therefore sought that allows sufficiently accurate monitoring of the state of the mechanical seal, with which not only fault monitoring is to be carried out, but also in the ideal case a description of the remaining residual life of the seal can be determined. This object is achieved by a method according to the features of claim 1. Advantageous embodiments of the method are the subject matter of the dependent claims. According to the invention, a method for determining the state of a mechanical seal is proposed, which is characterized by the following method steps: detecting at least one operating parameter indicative of an operating condition of the mechanical seal, In the case of a plurality of models, in particular a tribological model of the mechanical seal with the detected operating parameters as input variables and/or one or more tribological properties of the mechanical seal, and a thermal fluid and/or thermal structure model of the mechanical seal together with thermally relevant peripheral devices, heat sources and/or leaks and/or temperatures in the contact region of the mechanical seal are predicted, In the case of the application of a thermal fluid and/or thermal structure model of the mechanical seal, the contact state of the mechanical seal and/or the temperature characteristic curve in the sealing contact is dynamically reconstructed using the predicted heat source and/or leakage and the temperature t_mate measured at one component of the mechanical seal as input variables. The idea according to the invention is to use a layered model structure for the modeling of the mechanical seal in order to thereby be able to draw conclusions as precisely as possible about the actual state in the seal gap (i.e. the contact area of the mechanical seal). The layered model structure provides, on the one hand, a microscopic model for modeling the tribological conditions in the sealed contact and in the contact area. The external conditions of the mechanical seal (which also have an effect on the overall state of the seal) are modeled by means of a macroscopic model. The combination of these two model levels enables as accurate an illustration as possible of the overall state of the mechanical seal. Microscopic (tribological) models model the sealing rings of mechanical seals in terms of structure and thermodynamics. For this purpose, the contact surfaces thereof are considered together with the working fluid also located between the contact surfaces. The model may preferably be covered by expert models and software for sealing the contact, especially in connection with laboratory experiments for determining and calibrating tribological