Compressor and method for operating a compressor

Abstract

The invention relates to a method for avoiding drop impingement erosion in an axial compressor (1), wherein the axial compressor (1) has a rotatably mounted rotor (3) and a housing (5) arranged around the rotor (3), wherein a flow channel (7) is arranged between the rotor (3) and the housing (5), wherein the rotor (3) comprises compressor rotor blades (4), wherein the housing (5) comprises compressor guide blades (6), wherein the flow channel (7) is formed by the compressor guide blades (6) and compressor rotor blades (4), wherein at least one compressor guide blade (6) having a temperature device is designed in such a way that the compressor guide blade (6) can be heated, and the temperature device is designed in such a way that accumulations of a process medium on the surface (13) of the heated compressor guide blade (6) evaporate.

Description

2024PF00663 1 Description TITLE Compressors and methods for operating a compressor TECHNICAL AREA [OOO1] The invention relates to an axial compressor comprising a rotatably mounted rotor and a housing arranged around the rotor, wherein a flow channel is arranged between the rotor and the housing, wherein the rotor comprises compressor impeller blades, wherein the housing comprises compressor guide vanes, and wherein the flow channel is formed by the compressor guide vanes and compressor impeller blades.

[0002] Furthermore, the invention relates to a method for avoiding droplet impact erosion in an axial compressor, wherein the axial compressor comprises compressor impeller blades and compressor guide vanes. BACKGROUND

[0003] A compressor is typically used to increase the pressure of a process medium by converting the energy of an electric motor or turbine into a pressure force on the process medium. The process medium can be air, gas, refrigerant, or similar. Compressors are generally classified as positive displacement compressors, dynamic compressors, or turbo compressors, depending on the compression method used.

[0004] An axial compressor is designed to continuously pressurize the process medium. The process medium flows primarily parallel to the axis of rotation. This differs from other rotating compressors such as centrifugal compressors, where the flow of the process medium includes a radial component through the compressor. 2024PF00663 Two axial compressors essentially comprise a rotatably mounted rotor and a casing arranged around the rotor. A flow channel is formed between the rotor and the casing, defined by compressor guide vanes and compressor impeller blades, with the guide vanes located on the casing and the impeller blades on the rotor. The energy level of the process medium increases as it flows through the axial compressor because the impeller blades exert torque on the process medium. The guide vanes slow down the process medium and convert the circulating component of the flow into pressure. Compressors are typically driven by an electric motor or a steam or gas turbine.

[0006] During compressor operation, the process medium can accumulate on the surface of the compressor guide vane. This accumulation can lead to droplet formation, which can detach from the guide vane and impact a downstream component, typically a compressor impeller blade, at high speed. The impact of these droplets causes material loss from the surface, a process known as droplet impact erosion.

[0007] It can happen that, under inlet conditions in compressors that are close to the dew point of the process medium, e.g., in heat pump applications, droplet impact erosion occurs on the first impeller. This occurs preferentially with essentially wet or isentropic process media.

[0008] Furthermore, this droplet impact erosion can also occur at a later stage of compaction in so-called dry process media.

[0009] In some fluids, to prevent droplet erosion, it is usually ensured by process engineering that the process medium is superheated to a certain extent, which, however, is associated with losses in efficiency and only protects against the condensation of water droplets in wet fluids.

[0010] Another technical option (for wet fluids) is to place a so-called demister behind the evaporator, which catches droplets. 2024PF00663 3 This method also has efficiency disadvantages due to a certain pressure loss, which has a significant impact, for example, in the direct evaporation of water at low pressure levels. SUMMARY OF THE INVENTION

[0011] This is where the invention comes in. The compressor impeller blades must be protected from dripping erosion.

[0012] It is therefore an object of the invention to provide an axial compressor in which the occurrence of droplet impact erosion is avoided or at least effectively reduced.

[0013] This problem is solved by an axial compressor comprising a rotatably mounted rotor and a housing arranged around the rotor, wherein a flow channel is arranged between the rotor and the housing, wherein the rotor comprises compressor impeller blades, wherein the housing comprises compressor guide vanes, wherein the flow channel is formed by the compressor guide vanes and compressor impeller blades, wherein at least one compressor guide vane is designed with a temperature device such that the compressor guide vane can be heated.

[0014] Furthermore, the problem is solved by a method for avoiding droplet impact erosion in an axial compressor, wherein the axial compressor comprises compressor impeller blades and compressor guide vanes, wherein at least one compressor guide vane is designed with a temperature device such that the compressor guide vane is heated. DESCRIPTION OF THE INVENTION

[0015] The invention thus takes a step towards effectively preventing the formation of disruptive droplets. This is achieved by a temperature control device designed to heat the compressor guide vane in such a way that any accumulations of the process medium on the surface of the compressor guide vane, which would otherwise form droplets, evaporate. 2024PF00663 4

[0016] A heated hollow compressor guide vane is therefore proposed, whereby the heating steam is introduced into the interior of the hollow compressor guide vane from a downstream intake. This evaporates the liquid phase accumulations that form on the surface of the first guide row, which would otherwise accumulate into larger droplets at the trailing edge. These larger liquid phase accumulations pose the primary risk of droplet impact erosion.

[0017] A key aspect of the invention is that the temperature device is designed in such a way that the heating medium condenses in the hollow compressor guide vane.

[0018] Advantageous embodiments are the subject of the dependent claims.

[0019] The dependent claims list further advantages that can be combined in any way to achieve further advantages.

[0020] One advantage of the invention is that the equipment required in the overall system is reduced by the use of additional heat exchangers or demisters. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] An embodiment of the invention will be explained in more detail below with reference to the following figures.

[0022] The properties, features and advantages of this invention described above, as well as the manner in which they are achieved, will become clearer and more easily understood in connection with the following description of the exemplary embodiments, which are explained in more detail in conjunction with the drawings.

[0023] Identical components or components with the same function are marked with the same reference numerals. 2024PF00663 5

[0024] Exemplary embodiments of the invention are described below with reference to the drawings. These drawings are not intended to be drawn to scale; rather, where helpful for explanation, they are presented in a schematic and / or slightly distorted form. For further details regarding the teachings directly apparent from the drawings, reference is made to the relevant prior art.

[0025] They show:

[0026] FIG 1 a schematic representation of a compressor

[0027] FIG 2 a schematic representation of droplet formation

[0028] FIG 3 shows a schematic representation of an arrangement according to the invention.

[0029] FIG 4 shows a schematic representation of a cross-section of a compressor guide vane. DESCRIPTION OF THE EXECUTION FORMS

[0030] Figure 1 shows a schematic representation of an axial compressor 1 as an embodiment of a compressor.

[0031] The axial compressor 1 has a rotor 3 rotatably mounted about a rotational axis 2. Compressor impeller blades 4 are arranged on the rotor surface. For clarity, only one compressor impeller blade 4 is designated with the reference numeral 4.

[0032] A housing 5 is arranged around the rotor 3. On an inner surface of the housing 5, compressor guide vanes 6 are arranged opposite the compressor impeller blades 4. For the sake of clarity, only one compressor guide vane 6 is designated with the reference numeral 6.

[0033] The compressor guide vanes 6 are arranged opposite the compressor impeller vanes 4 in such a way that a flow channel 7 is formed through which a process medium flows during operation. The process medium flows 2024PF00663 6 in a flow direction 8 via a compressor inlet 9 to the compressor outlet 10.

[0034] The pressure and temperature of the process medium are increased. The process medium can be, for example, air, water vapor, carbon dioxide (CO2), or any other condensable medium.

[0035] During operation, the rotor 3 is driven and set into rotation by a machine, such as an electric motor (not shown) or a steam turbine (not shown). The mechanical energy of the machine is thereby converted into pressure energy of the process medium. At least one compressor guide vane 6 is equipped with a temperature control device such that the compressor guide vane 6 can be heated to minimize the effect of droplet impact erosion. The principle of droplet impact erosion is now explained in Figure 2. Figure 2 schematically shows the cross-section of compressor guide vanes 6 arranged one behind the other. The compressor guide vane 6 comprises a leading edge 11 and a trailing edge 12. During operation, conditions may arise such that an accumulation of the process medium is possible on the surface 13 of the compressor guide vane 6.This will now be explained in more detail using water vapor as a process medium.

[0038] In a first area 14 behind the trailing edge 12, the accumulation on the surface 13 can be carried along by the flow, forming water strands 15. In a second area 16, larger droplets 17 can form. The droplet size depends on the surface tension, the vapor pressure, and the relative velocity. During operation, the droplets inevitably collide with a downstream compressor blade 4, which would permanently lead to droplet impact erosion. The temperature control device prevents droplet formation, as explained in more detail in Figure 3. 2024PF00663 Figure 3 shows a schematic representation of an arrangement according to the invention. Figure 3 shows a cross-sectional view of the axial compressor 1 as seen in the flow direction 8. According to the invention, the compressor guide vane 6 is heated. This is achieved by making the compressor guide vane 6 hollow and allowing a heating medium to flow through it. The heating medium is guided radially through the compressor guide vane 6 via an outer ring 18. Condensation of the heating medium occurs in the compressor guide vane 6. The heating medium can be identical to the process medium. The heating medium is drawn from the flow channel 7 at a higher pressure level downstream via a tap line 19 and fed into the outer ring 18. The condensate that forms in the hollow compressor guide vane 6 is discharged via a drain 20 and returned to the tap line 19.The guide vane heating system draws only as much heating medium as is necessary to evaporate the truly dangerous liquid phase accumulations. A "safety margin" of the entire flow to the wet steam boundary is not required. This results in performance advantages.

[0042] Figure 4 shows a schematic cross-sectional view of the hollow compressor guide vane 6. Inside the compressor guide vane 6, the heating medium flows in a radial direction, so that the compressor guide vane 6 is heated in such a way that any accumulations of the process medium appearing on the surface evaporate, thus preventing droplet formation and thereby reducing droplet impact erosion in the axial compressor 1. Although the invention has been illustrated and described in detail by the preferred embodiment, the invention is not limited by the disclosed examples and other variants can be derived by a person skilled in the art without leaving the scope of protection of the invention.

Claims

2024PF00663 8 Claims 1. Axial compressor (1) comprising a rotatably mounted rotor (3) and a housing (5) arranged around the rotor (3), wherein a flow channel (7) is arranged between the rotor (3) and the housing (5), wherein the rotor (3) comprises compressor impeller blades (4), wherein the housing (5) comprises compressor guide vanes (6), wherein the flow channel (7) is formed by the compressor guide vanes (6) and compressor impeller blades (4), characterized in that at least one compressor guide vane (6) is designed with a temperature control device such that the compressor guide vane (6) can be heated.

2. Axial compressor (1 ) according to claim 1 , wherein the compressor guide vane (6) is hollow.

3. Axial compressor (1 ) according to claim 2, wherein the temperature device is designed such that a heating medium flows through the compressor guide vane (6) during operation.

4. Axial compressor (1) according to claim 3, wherein the heating medium is a condensable medium.

5. Axial compressor (1) according to claim 3, wherein the heating medium is steam.

6. Axial compressor (1) according to claim 3, wherein the heating medium is carbon dioxide.

7. Axial compressor (1 ) according to one of claims 3 to 6, wherein the temperature device is designed such that the heating medium condenses in the hollow compressor guide vane (6). 2024PF00663 9 8. Method for avoiding droplet impact erosion in an axial compressor (1), wherein the axial compressor (1) comprises compressor impeller blades (4) and compressor guide vanes (6), wherein at least one compressor guide vane (6) is designed with a temperature device such that the compressor guide vane (6) is heated.

9. Method according to claim 8, wherein the compressor guide vane (6) is hollow and a condensable heating medium flows through the compressor guide vane (6) such that the heating medium condenses.

10. Method according to claim 8 or 9, wherein the axial compressor (1) is supplied with a process medium, wherein the temperature device is designed such that accumulations of the process medium on the surface (13) of the heated compressor guide vane (6) evaporate.

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