Patent Application
20130287566
The invention relates to a plain bearing for a turbomachine rotor and to a turbomachine having the plain bearing.
A turbomachine has in principle a rotor. The turbomachine is, for example, a single-shaft compressor, the rotor of which has a shaft onto which impellers are threaded. The rotor is mounted at the longitudinal end regions of the shaft by means of bearings. The bearings are designed to absorb radial forces and/or axial forces which act on the rotor. The bearings can be plain bearings, in particular with self-lubricating properties. The plain bearings have a bearing body in the form of a bushing, in which the rotor is mounted. It is known to produce the bushing from a metal powder in a sintering operation and a pressing operation, in which use is made in particular of iron powder for the metal powder.
In chemical engineering plants, process gas is processed, with provision being made of turbo-compressors for compressing the process gas. If the process gas is chemically aggressive, the components of the turbo-compressor which come into contact with the process gas can be impaired. By way of example, crude gas containing hydrogen sulfide flows through a crude gas compressor in an ethylene plant. During such an operation of the crude gas compressor, an acid gas condition prevails, the definition of which is stipulated, for example, in accordance with ISO 15156. If the components which operate under the acid gas condition are produced from a high-strength steel, there is the risk of stress corrosion cracking in the high-strength steel. Under the influence of mechanical loading during operation of the turbo-compressor, the stress corrosion cracking can lead to damage or destruction of the components concerned. Serious damage can thereby arise in the crude gas compressor. This affects in particular the plain bearing, since the iron powder is not resistant to acid gas.
A remedy could be provided by selecting a polymer material instead of the iron powder. Although this has the effect that the plain bearing is suitable for acid gas applications, this plain bearing equipped with the polymer material has a considerably lower load-bearing capacity compared to the metallic, but acid-gas-unresistant, embodiment.
It is an object of the invention to provide a plain bearing for a turbomachine rotor and a turbomachine having the plain bearing, where the turbomachine is suitable for an acid gas application even though the plain bearing has a high load-bearing capacity and service life.
The object is achieved by the features of the independent claims. Advantageous configurations in this respect are indicated in the further patent claims.
The plain bearing according to the invention for the turbomachine rotor has a bearing body for mounting the turbomachine rotor and a solid lubricant powder for lubricating a bearing contact between the bearing body and the turbomachine rotor, wherein the bearing body is produced from an acid-gas-resistant, solid-solution-strengthened powder of a nickel-based material or from a martensitic, austenitic or ferritic-austenitic non-rusting powder of a steel material, and the solid lubricant powder is produced from an acid-gas-resistant material, and also the bearing body has a hardness of at most 40 Rockwell hardness HRC. It is preferable that the material is a nickel-based solid solution alloy.
The material of the bearing body preferably comprises at least 19.0% by weight chromium, at least 29.5% by weight nickel and cobalt and at least 2.5% by weight molybdenum, and is preferably solution-annealed or annealed. Alternatively, it is preferable that the material of the bearing body comprises at least 14.5% by weight chromium, at least 52% by weight nickel and cobalt and at least 12% by weight molybdenum, and also is solution-annealed or annealed. As a further alternative, it is preferable that the material of the bearing body comprises at least 19.5% by weight chromium, at least 29.5% by weight nickel and cobalt and at least 2.5% by weight molybdenum, and also is solution-annealed or annealed and, owing to cold work-hardening, has a yield strength of at most 1034 MPa. As an additional alternative, it is preferable that the material of the bearing body comprises at least 19% by weight chromium, at least 45% by weight nickel and cobalt and at least 6% by weight molybdenum and tungsten, and also is solution-annealed or annealed and, owing to cold work-hardening, has a yield strength of at most 1034 MPa. As a preferred alternative, the material of the bearing body comprises at least 14.5% by weight chromium, at least 52% by weight nickel and cobalt and at least 12% by weight molybdenum, and is preferably solution-annealed or annealed and, owing to cold work-hardening, has a yield strength of at most 1240 MPa.
The solid lubricant powder is preferably made of graphite, molybdenum disulfide or hexagonal boron nitride. Furthermore, the plain bearing preferably has a bearing bushing, which forms the bearing body.
The turbomachine according to the invention has the plain bearing, the turbomachine being suitable for processing acid gas. It is preferable that the turbomachine is a turbo-compressor for compressing process gas, in particular acid gas, contaminated with hydrogen sulfide.
The plain bearing according to the invention is of self-lubricating form with the acid-gas-resistant solid lubricant powder, with the powder made of the solid-solution-strengthened nickel-based alloy or the acid-gas-resistant martensitic, austenitic or ferritic-austenitic non-rusting powder of the steel material being provided for the bearing body, the material having a hardness of at most 40 Rockwell hardness HRC. As a result, the plain bearing according to the invention is suitable for use for the turbomachine which is intended for processing acid gas. Since the material for the bearing body and also the solid lubricant powder are resistant to acid gas, they can be used for the plain bearing in the turbomachine. The material advantageously has a high strength, as a result of which the plain bearing has a high load-bearing capacity.
Conventionally, non-ferrous metal alloys and polymer materials would be provided, for example, for a plain bearing bushing which is installed in the turbomachine subjected to acid gas. Compared to these materials, the nickel-based material or steel material provided according to the invention for the bearing body has a higher strength, as a result of which the plain bearing according to the invention has a higher service life compared to the conventional plain bearing.
The invention will be explained in more detail hereinbelow on the basis of exemplary embodiments.
A plain bearing for a turbomachine rotor has a bearing body for mounting the turbomachine rotor and a solid lubricant powder for lubricating a bearing contact between the bearing body and the turbomachine rotor. The bearing body is produced from an acid-gas-resistant, solid-solution-strengthened nickel-based material or from a martensitic, austenitic or ferritic-austenitic non-rusting powder of a steel material, the bearing body having a hardness of at most 40 Rockwell hardness HRC. The solid lubricant powder is produced from an acid-gas-resistant material, for example graphite, molybdenum disulfide or hexagonal boron nitride.
In a first exemplary embodiment, the material of the bearing body comprises at least 19.0% by weight chromium, at least 29.5% by weight nickel and cobalt and at least 2.5% by weight molybdenum, and is solution-annealed or annealed. In a second exemplary embodiment, the material of the bearing body comprises at least 14.5% by weight chromium, at least 52% by weight nickel and cobalt and at least 12% by weight molybdenum, and is solution-annealed or annealed.
If the plain bearing is equipped with the bearing body which is produced from the material according to the first exemplary embodiment or the material according to the second exemplary embodiment, the plain bearing is suitable for any conceivable acid gas application in the turbomachine.
In a third exemplary embodiment, the material of the bearing body comprises at least 19.5% by weight chromium, at least 29.5% by weight nickel and cobalt and at least 2.5% by weight molybdenum. The material is furthermore solution-annealed or annealed and, owing to cold work-hardening, has a yield strength of at most 1034 MPa. In a fourth exemplary embodiment, the material of the bearing body comprises at least 19% by weight chromium, at least 45% by weight nickel and cobalt and at least 6% by weight molybdenum and tungsten. The material is solution-annealed or annealed and, owing to cold work-hardening, has a yield strength of at most 1034 MPa. In a fifth exemplary embodiment, the material of the bearing body comprises at least 14.5% by weight chromium, at least 52% by weight nickel and cobalt and at least 12% by weight molybdenum. The material is furthermore solution-annealed or annealed and, owing to cold work-hardening, has a yield strength of at most 1240 MPa.
If the plain bearing is equipped with the bearing body which is produced from the material according to the third exemplary embodiment or the material according to the fourth exemplary embodiment, the plain bearing is suitable for an acid gas application in the turbomachine for which, for example, at an acid gas temperature of 232° C. a partial pressure of hydrogen sulfide in the acid gas of at most 200 kPa prevails, or at an acid gas temperature of 218° C. a partial pressure of hydrogen sulfide in the acid gas of at most 700 kPa prevails, or at an acid gas temperature of 204° C. a partial pressure of hydrogen sulfide in the acid gas of at most 1000 kPa prevails, or at an acid gas temperature of 177° C. a partial pressure of hydrogen sulfide in the acid gas of at most 1400 kPa prevails. Up to an acid gas temperature of 132° C., this plain bearing is suitable for any conceivable partial pressure of hydrogen sulfide in the acid gas.
If the plain bearing is equipped with the bearing body which is produced from the material according to the fourth exemplary embodiment or the material according to the fifth exemplary embodiment, the plain bearing is suitable for an acid gas application in the turbomachine for which, for example, at an acid gas temperature of 218° C. a partial pressure of hydrogen sulfide in the acid gas of at most 2000 kPa prevails. Up to an acid gas temperature of 149° C., this plain bearing is suitable for any conceivable partial pressure of hydrogen sulfide in the acid gas.
If the plain bearing is equipped with the bearing body which is produced from the material according to the fifth exemplary embodiment, the plain bearing is suitable for an acid gas application in the turbomachine for which, for example, at an acid gas temperature of 232° C. a partial pressure of hydrogen sulfide in the acid gas of at most 7000 kPa prevails. Up to an acid gas temperature of 204° C., this plain bearing is suitable for any conceivable partial pressure of hydrogen sulfide in the acid gas.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102011002868.4 | Jan 2011 | DE | national |
This application is the US National Stage of International Application No. PCT/EP2011/071987 filed Dec. 7, 2011 and claims benefit thereof, the entire content of which is hereby incorporated herein by reference. The International Application claims priority to the German application No. 10 2011 002 868.4 DE filed Jan. 19, 2011, the entire contents of which is hereby incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2011/071987 | 12/7/2011 | WO | 00 | 7/17/2013 |
