JP5820463B2 - Self-lubricating coating and method - Google Patents

Description

  Embodiments of the presently disclosed subject matter generally relate to methods and systems, and particularly to mechanisms and techniques that provide a self-lubricating coating.

  Over the last few years, soaring fossil fuels have increased interest in various aspects related to fossil fuel processing. Furthermore, there is a growing interest in making more efficient and reliable motors, turbines, compressors, etc. to facilitate good production and distribution of oil and gas-based products.

  Such a mechanical device generally includes a stator as a fixed portion and a rotor as a rotating portion. The rotor rotates with respect to the stator to perform one of compression of the medium, generation of electrical energy, or conversion of electrical energy into mechanical energy. The rotor needs to rotate with minimal mechanical friction and a specific temperature range relative to the stator. A large amount of heat is generated by the continuous rotation of the rotor and its weight (can be in the range of 20-20000 kg, increasing mechanical friction). This heat is mainly generated in the bearing that supports the rotor.

  Therefore, various mechanisms for cooling the bearing will be required. One such mechanism is to remove excess heat by continuously circulating a medium such as oil between the rotor and the bearing to cool the oil. A pump can be used for forced oil circulation. However, if the pump fails, the oil stops flowing and consequently prevents the removal of heat generated at the interface between the rotor and the bearing. Under such conditions, oil cannot be present at the interface between the rotor and the bearing, and the temperature will rise to a level that leads to damage to the rotor and / or bearing or other components of the machine.

  If a machine operator or dedicated system cannot immediately detect this abnormal condition and shut down the machine, then all the machine will be severely damaged, resulting in failure of all processes involving the machine. This is costly and undesirable in the oil and gas manufacturing industry. Even if a failure state of a mechanical device can be found quickly, the corresponding mechanical device immediately shuts down one mechanical device without interfering with the safety of other mechanical devices because the multiple mechanical devices are linked. If this is part of a process that is not possible, the affected machinery may not be able to be stopped.

  Accordingly, a system and method is provided that provides a time buffer between the moment when the machine is unable to operate properly and the moment when the machine is damaged due to high temperatures caused by, for example, an oil pump failure. Is desirable.

  One exemplary embodiment is a method of applying a self-lubricating coating to a substrate. The method comprises: spraying at least a liquid metal layer onto a substrate with a gas; adding a compound to the liquid metal when sprayed onto the substrate; and a porous layer containing the metal and the compound, Forming a porous layer including pores on the substrate; heating the porous layer to open the pores; and dipping the open pores in the grease material so that a portion of the grease material is at least one And allowing the porous layer to cool and close the pores to trap the grease material within the pores.

  Another exemplary embodiment is a method of operating a turbomachine having a safety mechanism for a bearing. Rotating the rotor relative to a turbomachine stator, supporting the rotor with a bearing including one or more porous layers comprising a metal and a compound forming a plurality of pores and a grease material stored in the pores And supplying lubricating oil to the bearing as the rotor rotates so that the operating temperature of the bearing is substantially constant.

  Yet another exemplary embodiment is a turbomachine, a stator configured to be fixed, a rotor configured to rotate relative to the stator, and a rotor that supports and rotates the rotor. A bearing configured to facilitate and a self-lubricating coating provided on the bearing or on the rotor. The self-lubricating coating includes one or more porous layers, the one or more porous layers including a metal and a compound forming a plurality of pores, and a grease material stored in the pores, When the operating temperature is equal to or lower than a predetermined temperature value, the pores are closed to trap the grease material.

  The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments, and together with the description, explain these embodiments.

Schematic of the mechanical apparatus which has a rotor and a stator. 1 is a schematic diagram of a substrate having a self-lubricating coating according to an exemplary embodiment. FIG. 2 illustrates an example of a porous layer according to an exemplary embodiment. 6 is a flowchart illustrating a method for applying a self-lubricating coating to a substrate according to an exemplary embodiment. 6 is a flowchart illustrating a method for operating a turbomachine having a safety mechanism for a bearing according to an exemplary embodiment.

  Exemplary embodiments refer to the accompanying drawings. The same reference numbers in different drawings indicate the same or similar components. The following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims. The following embodiments will be described with respect to compressor terminology and structure for simplicity. However, the embodiment described below is not limited to a compressor, and can be applied to other systems including a rotor supported by a bearing.

  Reference throughout this specification to “one embodiment” or “an embodiment” includes at least one embodiment of the disclosed subject matter with the specific features, structures or characteristics described in connection with the embodiment. Means that. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

  In an exemplary embodiment, a portion of the rotor, bearings, or both are coated with a self-lubricating coating to store grease material while the machine is operating at normal temperatures, and the machine temperature is predetermined. The grease material is discharged when the temperature exceeds the temperature threshold.

  In the exemplary embodiment shown in FIG. 1, the compressor 10 includes a rotor 12 that is adapted to rotate specifically relative to the rotor 14. The rotor 12 is supported by one or more bearings 16 at both ends, for example. Various bearings are known in the art and any bearing can be used to support the rotor 12. An example of a bearing is the journal bearing described in US Pat. No. 6,361,215, the disclosure of which is incorporated herein by reference.

  The journal bearing 16 uses one or more pads 18 that support the rotor 12, and oil is injected between the pad 18 and the rotor 12 to the interface 20 to reduce mechanical wear and / or the interface. Is supposed to cool. A pump (not shown) may be used to pump oil through each pad passage 22 at the interface 20 between the pad 18 and the rotor 12. If no oil can be supplied to the interface 20, the interface temperature will rise above an acceptable value that may damage the bearing 16, the rotor 12, or both.

  In the exemplary embodiment shown in FIG. 2, the rotor 12 or a portion of the bearing 16 or both can be coated with a self-lubricating layer 24. The self-lubricating layer 24 can be deposited on a substrate 26, which can be one of the rotor 12 and / or bearing 16, as shown in FIG.

  When the self-lubricating layer 24 is deposited on the rotor 12, it is desirable to deposit the self-lubricating layer so that it faces the bearing 16 directly. The self-lubricating layer 24 can include a base material 28 that is deposited on the substrate 24. Examples of the base material include bearing metals such as gray cast iron, stainless steel, carbon steel, and non-ferrous alloys. In one application, the base material is a plastic containing material including, for example, a low carbon component and a high carbon component of Fe, Ni, or cobalt. In other applications, the base material does not contain Cr. In yet another application, the base material is plastic because it can contain non-ferrous metals. The base material can be deposited by a conventionally known method. For example, the base material can be sprayed onto the substrate. However, in one application, the base material layer 28 is not part of the self-lubricating layer 24. Base material layer 28 is deposited to ensure good adhesion between self-lubricating layer 24 and substrate 26.

A porous layer 30 providing a self-lubricating function is formed on the base material layer 28 or directly on the substrate 26. The porous layer 30 can contain a metal and a compound that promote pore formation in the porous layer 30. The metal can be one or more bearing metals, such as gray cast iron, stainless steel, carbon steel, based on the application, desired layer hardness, and bearing load. The compound can be one or more graphite powders, molybdenum disulfide (MoS ₂ ), tungsten disulfide (WS ₂ ). The metal is sprayed on the base material layer 28 as a liquid. For example, electric arc or plasma spraying can be used to spray liquid metals and compounds. The inert gas under pressure can be used to add the compound into the molten metal as well as to supply the molten metal from a gun or other equipment used to coat the substrate. For example, the inert gas can be nitrogen (N).

  The porous layer 30 is shown in FIG. 3 and has a plurality of pores 32 distributed throughout the metal and compound mixture 34. The number of the plurality of pores 32 depends on many variables. For example, the number of pores depends on the temperature at which the liquid metal is sprayed onto the substrate, the pressure of the inert gas, the distance between the gun that sprays the liquid metal and the substrate, the particular metal used, the particular compound used Etc. can depend on. In one application, the self-lubricating layer 30 has a thickness in the range of a few micrometers to a few millimeters.

  When the porous layer 30 is formed on the substrate 26 and the assembly temperature is as low as room temperature (about 25 ° C.), the pores are closed. For example, even if the porous layer 30 is immersed in a liquid bath Only a small amount of liquid enters the pores of the porous layer 30. However, when the porous layer 30 and the substrate 26 are exposed to a hot oil bath (eg, immersed), the pores 32 of the porous layer 30 open and the oil begins to fill the pores. The high temperature range can be set to 80 to 500 ° C., for example, depending on the type of oil (whether or not it is synthesized). Although oil is illustratively used, some grease material can be used to partially fill some or all of the pores of the porous layer 30.

  The substrate 26 and porous layer 30 are then cooled to room temperature and the pores are sealed so that the absorbed grease material is stored inside the pores 32. The substrate with the self-lubricating layer 30 is then used in one or more of the aforementioned mechanical devices. Therefore, when this mechanical device cannot supply oil to the interface between the rotor and the bearing, the temperature of the interface rises until the temperature at which the pores of the self-lubricating layer 30 open exceeds the temperature of the porous layer 30. Begins releasing grease material to the interface between the rotor and bearing. Depending on the size and distribution on the bearings and / or the rotor, this self-lubricating layer 30 can be several times, if not up to several hours, even if the main oil supply mechanism of the machine fails. Gives safe operation in minutes. In this way, the operator is provided with the time required to shut down the entire process line in a controlled manner without compromising the safety of the other mechanical devices that make up the process line.

  Although it is intuitively understood that the thick self-lubricating layer 30 is provided in order to give the grease material for a long time, it has been found that the thick layer is prone to cracking and thus has a short life. Furthermore, the grease material leaks earlier than expected due to cracks in the thick layer, and the adhesion of the porous layer to the substrate may be impaired. Conversely, a thin layer is undesirable because it cannot store enough grease material. Accordingly, the appropriate thickness of the self-lubricating layer 30 depends on the type of mechanical device, the weight of the rotor, the number of pads, the number of bearings, and the like.

  In the exemplary embodiment shown in FIG. 4, a method for applying a self-lubricating coating to a substrate is shown. The method includes the step 400 of spraying at least a liquid metal layer onto a substrate using a gas, the step 402 of adding a compound to the liquid metal while being sprayed on the substrate, and the substrate containing a plurality of fine particles containing the metal and the compound. Step 404 for forming a porous layer having pores, Step 406 for heating the porous layer to open the pores, and filling the pores with the grease material so that the grease material is stored in one or more pores Step 408 including cooling 410 the porous layer to close the pores and trap the grease material within the pores.

The gas used to deposit the liquid metal can be an inert gas. However, inexpensive N ₂ gas can be used to deposit the iron layer. N ₂ gas is desirable because it can impart plasticity to the porous layer. N ₂ gas is superior to argon or compressed air because it prevents oxidation of the liquid metal alloying elements and does not alter the composition of the deposited layer.

  In the exemplary embodiment shown in FIG. 5, a method for providing a safety mechanism for a turbomachine bearing is disclosed. The method comprises a bearing 500 comprising a step 500 of rotating a rotor relative to a stator of a turbomachine, metals and compounds forming a plurality of pores, and one or more porous layers comprising a grease material stored in the pores. Step 502 for supporting the rotor, and Step 504 for supplying lubricating oil to the bearing during rotation of the rotor so that the operating temperature of the bearing is substantially constant.

  The disclosed exemplary embodiments provide a system and method for supplying grease material when a dedicated supply of grease material fails. It should be understood that this description is not intended to limit the invention. On the contrary, the exemplary embodiments are intended to protect alternatives, modifications and equivalents that fall within the spirit and scope of the invention as defined by the appended claims. Furthermore, in the detailed description of the exemplary embodiments, numerous specific details are set forth in order to provide a comprehensive understanding of the claimed invention. However, those skilled in the art will appreciate that various embodiments may be practiced without such specific details.

  Although features and elements of exemplary embodiments of the invention have been described in particular embodiments in particular combinations, each feature or element is independent of the other features and elements of the embodiment or is used herein. It can be used in various combinations with or without other disclosed features and elements.

  This written description uses the disclosed subject matter to practice the invention, including any person skilled in the art to implement and utilize any device or system and to implement any method of inclusion. Make it possible. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other embodiments are intended to be within the scope of the claims.

Claims (7)

A method of applying a self-lubricating coating to a substrate,
Spraying at least a layer of liquid metal onto the substrate with a gas;
Adding a compound to the liquid metal as it is sprayed onto the substrate;
Forming a porous layer containing the metal and the compound on the substrate, the porous layer containing a plurality of pores;
Heating the porous layer to open the pores;
Soaking the open pores in the grease material so that a portion of the grease material remains in one or more pores;
Cooling the porous layer to close the pores and trapping the grease material inside the pores;
Including a method.   The method according to claim 1, wherein the liquid metal is one of bearing metals, gray cast iron, stainless steel, carbon steel, or non-ferrous alloy. The method according to claim 1 or 2, wherein the compound is one of graphite powder, molybdenum disulfide (MoS ₂ ), tungsten disulfide (WS ₂ ), or a combination thereof.   In order to form a porous layer on the base material so as to adhere well to the substrate, before the step of spraying, the carbon content is low and Fe, Ni or cobalt, or plastic non-ferrous metal content The method according to claim 1, further comprising forming a high amount of base material layer.   The method according to claim 1, wherein the heating is performed by immersing the porous material in a grease material at a predetermined temperature.   The method according to claim 1, wherein the substrate is a compressor bearing. The method according to claim 1, wherein the gas contains nitrogen (N).