MX2012011628A

MX2012011628A - Self-lubricated coating and method.

Info

Publication number: MX2012011628A
Application number: MX2012011628A
Authority: MX
Inventors: Ion Savu
Original assignee: Nuovo Pignone Spa
Priority date: 2010-04-06
Filing date: 2011-04-01
Publication date: 2012-11-30
Also published as: CN102812147A; ITCO20100014A1; JP2013530303A; JP5820463B2; CN102812147B; AU2011237981A1; IT1399157B1; KR20130040790A; BR112012025269A2; US20130202405A1; EP2556179A1; WO2011124534A1; RU2012142135A; CA2794792A1

Abstract

Coating and method for providing a self-lubricated coating on a substrate. The method includes spraying with an inert gas at least a layer of liquid metal on the substrate; adding a compound to the liquid metal while being sprayed on the substrate; forming a porous layer on the substrate that includes the metal and the compound, where the porous layer has plural pores; heating the porous layer to open the pores; flooding the open pores with a greasing substance such that part of the greasing substance is stored in one or more pores; and cooling the porous layer to close the pores and trap the greasing substance inside the pores.

Description

AUTO-LUBRICATED COATING AND METHOD Field of the Invention The embodiments of the described subject matter are generally related to methods and systems and more particularly, with mechanisms and techniques for providing a self-lubricating coating.

Background of the Invention In past years, with the increase in the price of fossil fuels, interest in various aspects related to the processing of fossil fuels has increased. In addition, there is an increasing interest to produce engines, turbines, compressors, etc., more reliable and more efficient, to facilitate the production and distribution of petroleum products or gas-based products.

Generally, such machines include a fixed part, a stator, and a rotating part, the rotor. The rotor is configured to rotate relative to the stator to achieve one of compressing a medium, producing electrical energy, or transforming electrical energy into mechanical energy. The rotor needs to rotate relative to the stator with minimal friction and in a certain temperature range. Due to the continuous rotation of the rotor and its weight (which can be between 20 and 20,000 kg and increases friction), a large amount of heat is produced. The heat appears mainly in the bearings to support the rotor.

In this way, different mechanisms can be used to cool the bearings. A mechanism like this is to continuously circulate a medium, oil for example, between the rotor and the bearings and remove excess heat when cooling the oil. A pump can be used to force oil circulation. However, when the pump fails, the oil flow stops and, consequently, stops the removal of the heat developed at the interface between the rotor and the bearing. Under these circumstances, there will be no oil present at the interface between the rotor and the bearing, which determines the increase in bearing temperature to a point that will result in damage to the rotor and / or the bearing or any other component of the machine. .

When this abnormal condition is not quickly identified by the operator of the machine or by a dedicated system for the machine to stop, the entire machine can be seriously damaged, which results in the interruption of the entire process in which the machine is involved. , which is expensive and not convenient in the oil and gas industry Even when a machine failure condition is quickly identified, it is sometimes impossible to stop the affected machine, since the machine is part of a process where multiple machines they are coordinated and the rapid suspension of a machine is not possible without interfering with the safety of other machines.

In accordance with this, it is desirable to provide systems and methods that offer the machine operator a time memory between the time when the machine has failed to function correctly and the time when the machine is damaged, due to, for example, the high temperature that appears when the oil pump fails.

Brief Description of the Invention In accordance with an exemplary embodiment, a method for providing a self-lubricating coating on a substrate is described. The method includes spraying with an inert gas, at least one layer of liquid metal on the substrate, adding a compound to the liquid metal while it is sprayed on the substrate, forming a porous layer on the substrate, which includes the metal and the compound, wherein the porous layer has multiple pores, heat the porous layer to open the pores, flood the open pores with a fatty substance, such that the part of the fatty substance is stored in one or more pores and cool the porous layer to close the pores. pores and trap the oily substance inside the pores.

In accordance with another exemplary embodiment, a method for operating a turbo-machinery having a safety mechanism for a bearing is described. The method includes rotating a rotor relative to the stator of the turbo-machinery, supporting the rotor with a bearing that includes the at least one porous layer, the at least one porous layer includes a metal and a compound that form multiple pores and a fatty substance stored in the pores and provide a lubricant in the bearing while the rotor rotates, so that the operating temperature of the bearing is essentially constant.

According to another exemplary embodiment, a turbo-machinery is described which includes a stator configured to be fixed, a rotor configured to rotate relative to the stator, a bearing configured to support the rotor and facilitate the rotation of the rotor and a self-covering. -lubricated provided in the bearing or in the rotor. The self-lubricating coating includes at least one porous layer, the at least one porous layer includes a metal and a compound forming multiple pores and a fatty substance stored in the pores and the pores are closed, which traps the oily substance when the operating temperature of the bearing is below a predetermined value.

Brief Description of the Drawings The accompanying drawings that are incorporated and that constitute part of the specification, illustrate one or more modalities and together with the description, explain these modalities. In the drawings: Figure 1 is a schematic diagram of a machine having a rotor and a stator.

Figure 2 is a schematic diagram of a substrate having a lubricant coating in accordance with an exemplary embodiment.

Figure 3 is an illustration of a porous layer in accordance with an exemplary embodiment.

Figure 4 is a flow diagram illustrating a method for providing a lubricant coating on a substrate, in accordance with an exemplary embodiment; Y Figure 5 is a flow chart illustrating a method for operating a turbo-machinery that has a safety mechanism for a bearing, in accordance with an exemplary embodiment.

Detailed description of the invention The following description of the exemplary embodiments refers to the accompanying drawings. The same reference numbers in different drawings identify the same element or similar elements. The following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims. The following modalities are described, for simplicity, with respect to the terminology and structure of a compressor. However, the embodiments described herein are not limited to compressors, rather, they can be applied in other systems that include a rotor supported by bearings.

The reference through the specification to "one modality" or "modality" means that a particular characteristic or structure described in connection with a modality is included in at least one embodiment of the described subject. In this way, the appearance of the phrases "one modality" or "the modality" in several places in the specification does not necessarily refer to the same modality. In addition, particular features or structures may be combined in any appropriate form in one or more embodiments.

According to an exemplary embodiment, part of the rotor, the bearing or both are coated with a lubricant coating which is configured to store a fatty material, while the machine operates at a normal temperature and to release the fatty material when the temperature of the machine it increases over a certain threshold temperature.

According to an exemplary embodiment in Figure 1, a compressor 10 includes, among other things, a rotor 12 that is configured to rotate relative to the rotor 14. The rotor 12 is supported, for example, at both ends, by one or more bearings 16. The different bearings are well known in the art and any of these bearings can be used to support the rotor 12. An example of such bearing is a journal bearing, which is described in the US Pat. America No. 6,361, 215, the content of which is hereby incorporated by reference in its entirety.

A die bearing 16 uses one or more bearings 18 which support the rotor 12 and the oil is injected between the bearings 18 and the rotor 12 at an interface 20 to reduce friction and / or cool the interface. A pump (not shown) can be used to pump the oil through a channel 22 in each bearing at interface 20 between the bearing and rotor 12. When the oil fails to be delivered at interface 20, the temperature in this The interface will increase beyond an acceptable value, which can damage the bearing 16, the rotor 12 or both.

In accordance with an exemplary embodiment shown in Figure 2, a portion of either of the rotor 12, or the bearing 16 or both can be coated with a self-lubricating layer 24. The self-lubricated layer 24 can be deposited, as shown in Figure 2, on a substrate 26, which can be one of the rotor 12 and / or the bearing 16. When the self-lubricating layer 24 is deposited on the rotor 12 , it is desirable that this layer is deposited to face directly on the bearing 16.

The layer 24 may include a base material 26 that is deposited on the substrate 24. The base material may include a metal used for the bearing, e.g., gray cast iron, stainless steel, carbon steel, non-ferrous alloys, etc. . In one application, the plastic base material, for example, includes a material with a low carbon content and high Fe, Ni or Cobalt content. In another application, the base material does not include Cr. In another application, the base material may include a non-ferrous metal so that the base material is plastic. The base material can be deposited with methods known in the art. For example, the base material can be sprayed onto the substrate. However, in one application, the layer 28 of the base material is not part of the layer 24. The layer 28 of the base material is deposited to ensure a better adhesion between the self-lubricated layer 24 and the substrate 26.

A porous layer 30 providing the self-lubricating functionality is formed in the base material layer 28 or directly in the substrate 26. The porous layer 30 may include a metal and a pore-forming compound in the porous layer 30. The metal can be one or more of a metal used for the bearing, for example, cast gray iron, stainless steel, carbon steel, etc., depending on the application, the desired hardness of the layer, the load of the bearings. The compound may be one or more of a graphite powder, molybdenum disulfide (MoS2), tungsten sulfide (WS2). The metal is sprayed as a liquid in the base metal layer 28. For example, it You can use an electric arc or a plasma spray to spray the liquid metal and the compound. An inert gas under pressure can be used and not only deliver the molten metal from the gun or other device used to coat the substrate, but also to insert the compound into the molten metal. For example, the inert gas can be nitrogen (N).

The porous layer 30 is shown in Figure 3 to have multiple pores 32 distributed through the mixture 34 of the metal and the composite. The number of multiple pores 32 depends on many variables. For example, the number of pores may depend on the temperature at which the liquid metal is sprayed on the substrate, the pressure of the inert gas, the distance between the spray gun on the liquid metal and the substrate, the specific metal used, the specific compound used, etc. In one application, the thickness of the self-lubricating layer 30 is between micrometers and millimeters.

Once the porous layer 30 is formed in the substrate and the assembly temperature is lowered to approximately room temperature (eg, 25 ° C), the pores are closed, for example, when the porous layer 30 is immersed in a liquid bath, a minor amount of that liquid enters the pores of the layer 30. However, when the layer 30 together with the substrate 26 are exposed (for example, submerged) inside a high temperature oil bath , the pores 32 of layer 30 open and the oil begins to flood the pores. The high temperature range can be from 80 to 500 ° C, depending for example on the type of oil (synthetic or not, etc.). The oil is used as an example, but any fatty material can be used to partially fill part or all of the pores in layer 30.

The substrate 26 and layer 30 are then cooled to room temperature to seal the pores, so that the fatty material absorbed is stored within the pores 32. Such a substrate having the self-lubricating layer 30 is then used in one or more machines described above. Thus, when a machine fails to provide the oil at an interface between the rotor and the bearing, the temperature at the interface increases beyond the temperature to open the pores of the self-lubricating layer 30, which determines that the Porous layer 30 begins to release the fatty material at the interface between the rotor and the bearing.

Such self-lubricating layer 30, depending on its size and its distribution in the bearing and / or the rotor, can provide the machine operator with several minutes, if not hours for safe operation, although the main oil supply mechanism of the machine has failed. In this way, the operator has the time necessary to suspend the entire processing line in a controlled manner without altering the safety of the other machines that form the processing line.

Although it may be logical to provide a thick self-lubricating layer 30 in order to provide a longer supply of the fatty material, it has been found that a thick layer is prone to cracking and therefore to a shorter shelf life. In addition, cracks in the thick layer allow the fatty material to escape earlier than desired and can also compromise the adhesion of the porous layer with the substrate. On the contrary, a thin layer is not desirable, since not enough fatty material can be stored. In this way, the proper thickness of the self-lubricating layer 30 depends on the type of machine, the weight of the rotor, the number of bearings, etc.

In accordance with an exemplary modality illustrated in Figure 4, a method for providing a lubricant coating on a substrate is described. The method includes a step 400 of spraying with a gas at least one layer of the liquid metal into the substrate, a step 402 of adding a compound into the liquid metal while spraying onto the substrate, a step 404 to form a porous layer in the substrate. the substrate, which includes the metal and the composite, wherein the porous layer has multiple pores, a step 406 of heating the porous layer to open the pores, a step 408 of flooding the open pores with a fatty substance, so that part of the fatty substance is stored in one or more pores, and a step 410 of cooling the porous layer to close the pores and trap the fatty substance within the pores.

It should be noted that the gas used to deposit the liquid metal may be an inert gas. However, to deposit ferrous layers, an N2 gas can be used, since N2 is more economical. Also, the N2 gas can provide greater plasticity in the porous layer, which is desirable. N2 gas is better than argon or compressed air, since this gas prevents the oxidation of alloying elements in the liquid metal and does not alter the composition of the deposited layer.

In accordance with an exemplary embodiment shown in Figure 8, a method is described for providing a mechanism for Safety for a bearing in a turbo-machinery. The method includes a step 500 for rotating a rotor relative to a stator of a turbo-machinery, a step 502 for supporting the rotor with a bearing including at least one porous layer, the at least one porous layer includes a metal and a compound forming multiple pores) a fatty substance stored in the pores and a step 504 of providing a lubricant in the bearing, while the rotor rotates, so that the operating temperature of the bearing is essentially constant.

The described embodiments provide a system and method for providing a fatty material when a dedicated supply of fatty 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 encompass alternatives, modifications and equivalents that are included in the spirit and scope of the invention, as defined by the appended claims. Furthermore, in the detailed description of the exemplary embodiments, many details are set forth in order to provide greater understanding of the claimed invention. However, persons skilled in the art will be able to understand that different modalities can be practiced without such details.

Although the features and elements of the exemplary embodiments are described in the embodiments in particular combinations, each characteristic or element can be used alone without other characteristics and elements of the modalities or in various combinations with or without the features and elements described herein.

The written description uses examples of the described subject matter to enable those skilled in the art to practice the same, including making and using any device or system and carrying out the incorporated methods. The patentable scope of the subject is defined by the claims and may include other examples contemplated by persons skilled in the art. Such examples are intended to be within the scope of the claims.

Claims

1. A method for providing a lubricant coating on a substrate, the method is characterized in that it comprises: spraying at least one layer of the liquid metal on the substrate with a gas; add a compound in the liquid metal while it is sprayed on the substrate; forming a porous layer on the substrate including the metal and the composite, wherein the porous layer has multiple pores; heat the porous layer to open the pores; induce open pores with a fatty substance so that part of the fatty substance is stored in one or more pores; and cooling the porous layer to close the pores and trap the oily substance within the pores.

2. The method according to claim 1, characterized in that the liquid metal is one of a metal used for a bearing, cast gray iron, stainless steel, carbon steel or non-ferrous alloys.

3. The method according to claim 1 or claim 2, characterized in that the compound is one of a graphite powder, molybdenum disulfide (M0S2), tungsten sulfide (WS2) or a combination thereof.

4. The method of compliance with any of the previous claims, characterized in that it comprises: provide a base material that includes a low content of carbon and a high content of Fe or cobalt or non-ferrous metal, plastic in the substrate before spraying it, so that the porous layer is formed in the base material for better adhesion of the substrate

5. The method according to any of the preceding claims, characterized in that the heating is achieved by immersing the porous material in the fatty substance at a predetermined temperature.

6. The method according to any of the preceding claims, characterized in that the substrate is a bearing of a compressor.

7. The method according to any of the preceding claims, characterized in that the gas includes nitrogen (N).

8. A method for operating a turbo-machinery having a safety mechanism for a bearing, the method is characterized in that it comprises: turn an arrow in relation to the stator of the turbo-machinery; supporting the arrow with a bearing including at least one porous layer, the at least one porous layer includes a metal and a compound that form multiple pores and the fatty substance is stored in the pores; Y provide a lubricant in the bearing while the shaft rotates so that the operating temperature of the bearing is essentially constant.

9. The method according to claim 8, characterized in that it comprises: fail to provide the lubricant; increase the operating temperature of the bearing; Y open the pores of at least one porous layer, so that the stored fatty substance exits the pores and lubricates the bearing. 1Q. A turbo-machinery characterized because it comprises. a stator configured to be fixed; an arrow configured to rotate relative to the stator; a bearing configured to support the arrow and facilitate the rotation of the arrow; Y a lubricant coating provided on the bearing or the arrow; wherein the lubricant coating includes at least one porous layer, the at least one porous layer includes a metal and a compound that form multiple pores and a fatty substance stored in the pores; Y The pores are closed, which traps the oily substance when the operating temperature of the bearing is below a predetermined value.