Compressors, for example, centrifugal compressors, operate to increase a pressure of a compressible working fluid, e.g., process gas. The process gas is received via one or more inlets at an input end of the compressor and passes through one or more impellers disposed in series on a rotatable cylindrical shaft. The shaft and the impellers may be driven by one or more motors coupled to the shaft. The pressure of the process gas increases as the process gas passes from one impeller to the next until the process gas reaches the final impeller. The compressed process gas is then expelled from the compressor via one or more outlets located at a discharge end of the compressor at a pressure greater than the pressure at which the process gas was input to the compressor.
A balance piston 114, including an accompanying balance piston seal (not shown), may be arranged on the shaft 104 between the motor 102 and the compressor 100. The balance piston 114 is typically located behind the final impeller 112 and the backside (for example, the side of the balance piston 114 facing the motor 102 in
The National Association of Corrosion Engineers (NACE) Standards specify, among other things, the proper materials required to provide good service life of machinery used in acid gas environments. A NACE compliant material or component is substantially resistant to corrosion, such as the type that may occur upon exposure of a non-NACE compliant material to acid gas. Typically, materials that are exposed to the acid gas, e.g., the balance line, drillings (holes) in the compressor head and case, and other external pipes handling the acid gas, etc., are protected using NACE compliant claddings or protective sleeves.
The balance line and other external pipes that return the balance piston leakage tend to be large in size given the relatively high flow rate of the balance piston leakage passing through them and thus occupy considerable space. Also, the drillings in the compressor head typically are compound drillings (e.g., several holes in different directions) and installing claddings or protective sleeves on these compound drillings is difficult.
What is then needed is a relatively convenient method for returning the balance piston leakage to the input end of the compressor without using external plumbing or large complex drilled passages in the compressor heads or casing.
Example embodiments of the disclosure provide a compressor. The compressor may include an inlet at an input end of the compressor and an outlet at a discharge end of the compressor. The inlet may be configured to receive a working fluid and the outlet may be configured to expel the working fluid having a greater pressure. The input end and the discharge end may be axially separated. The compressor may also include a rotatable shaft extending axially between the input end and the discharge end, an impeller mounted about the rotatable shaft between the inlet and the outlet, a balance piston mounted about the rotatable shaft and disposed immediately following the impeller from the input end, and a balance piston seal mounted about the balance piston. The rotatable shaft may define a passageway fluidly coupling the inlet and the outlet. The passageway may be configured to receive at least a portion of the working fluid flowing across the balance piston seal and to supply the portion of the working fluid to the input end.
Example embodiments of the disclosure may also provide a shaft of a compressor. The shaft may include a first shaft section defining a first cavity axially extending therein and a plurality of inlet holes on an outer surface of the first shaft section, and a second shaft section defining a second cavity axially extending therein and a plurality of outlet holes on an outer surface of the second shaft section. The plurality of inlet holes may be in fluid communication with the first cavity and the plurality of outlet holes may be in fluid communication with the second cavity. The first cavity and the second cavity may form a passageway fluidly coupling the plurality of inlet holes and the plurality of outlet holes.
Example embodiments of the disclosure may further provide a compressor. The compressor may include an inlet at an input end of the compressor, an outlet at a discharge end of the compressor, and a rotatable shaft extending axially between the inlet and the outlet. The inlet may be configured to receive a working fluid and the outlet may be configured to expel the working fluid having a greater pressure. The rotatable shaft may define a passageway fluidly coupling the inlet and the outlet. The input end and the discharge end may be axially separated. The compressor may also include an impeller mounted about the rotatable shaft between the inlet and the outlet, a balance piston mounted about the rotatable shaft and disposed immediately following the impeller from the input end, and a balance piston seal mounted about the balance piston. The rotatable shaft may include a first shaft section and a second shaft section. The first shaft section may define a first cavity and a plurality of inlet holes on an outer surface of the first shaft section. The plurality of inlet holes may be in fluid communication with the first cavity. The second shaft section may define a second cavity and a plurality of outlet holes on an outer surface of the second shaft section. The plurality of outlet holes may be in fluid communication with the second cavity. The first cavity and the second cavity may form the passageway.
The present disclosure is best understood from the following detailed description when read with the accompanying Figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.
It is to be understood that the following disclosure describes several exemplary embodiments for implementing different features, structures, or functions of the invention. Exemplary embodiments of components, arrangements, and configurations are described below to simplify the present disclosure; however, these exemplary embodiments are provided merely as examples and are not intended to limit the scope of the invention. Additionally, the present disclosure may repeat reference numerals and/or letters in the various exemplary embodiments and across the Figures provided herein. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various exemplary embodiments and/or configurations discussed in the various Figures. Moreover, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed interposing the first and second features, such that the first and second features may not be in direct contact. Finally, the exemplary embodiments presented below may be combined in any combination of ways, i.e., any element from one exemplary embodiment may be used in any other exemplary embodiment, without departing from the scope of the disclosure.
Additionally, certain terms are used throughout the following description and claims to refer to particular components. As one skilled in the art will appreciate, various entities may refer to the same component by different names, and as such, the naming convention for the elements described herein is not intended to limit the scope of the invention, unless otherwise specifically defined herein. Further, the naming convention used herein is not intended to distinguish between components that differ in name but not function. Additionally, in the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to.” All numerical values in this disclosure may be exact or approximate values unless otherwise specifically stated. Accordingly, various embodiments of the disclosure may deviate from the numbers, values, and ranges disclosed herein without departing from the intended scope. Furthermore, as it is used in the claims or specification, the term “or” is intended to encompass both exclusive and inclusive cases, i.e., “A or B” is intended to be synonymous with “at least one of A and B,” unless otherwise expressly specified herein.
As illustrated in
The protrusion 222 may also define a cavity 226 that may be configured to collect debris (e.g., weld splatter generated when welding the first shaft section 216 and the second shaft section 218) produced when coupling the first shaft section 216 and the second shaft section 218 together, thereby preventing the debris from entering the passageway 207. The outer cylindrical surface 212 of the hollow shaft 202 may be finish grinded so as to create a relatively smooth outer cylindrical surface 212. It should be noted that the size and shape of the inlet and outlet holes and the inside diameter of the passageway may be variable and may depend, e.g., on frame size of the compressor, impeller bore size, flow requirements of the compressor, and/or any space restrictions. The plurality of inlet holes 210 and the plurality of outlet holes 214 may be disposed at a same radial distance from the axis of rotation 228 of the hollow shaft 202. In an example embodiment, a number of outlet holes 214 may be the same as a number of inlet holes 210.
Example embodiments disclosed above may provide numerous advantages over the existing designs. The hollow shaft 202 is beneficial in compressors that need large balance return plumbing. The hollow shaft 202 may reduce the need for such plumbing, thereby freeing up valuable space on heads and casings. As a result, the compressor heads may also be reduced in size. The hollow shaft 202 may result in improved rotor dynamics. For example, the hollow shaft 202 may be rotor dynamic neutral in that the loss in the shaft stiffness (as a result of being hollow) is offset by the loss in the rotor mass. Also, a reduction in the external plumbing and improved rotor dynamics may result in cost savings.
The foregoing has outlined features of several embodiments so that those skilled in the art may better understand the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.
This application claims priority to PCT Patent Application Ser. No. PCT/US2014/040437, filed on Jun. 2, 2014 and U.S. Provisional Patent Application Ser. No. 61/831,655, filed on Jun. 6, 2013. These priority applications are hereby incorporated by reference in their entirety into the present application to the extent consistent with the present application.
Filing Document | Filing Date | Country | Kind |
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PCT/US2014/040437 | 6/2/2014 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
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WO2014/197343 | 12/11/2014 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
20050118025 | Hiegemann | Jun 2005 | A1 |
20070257444 | Childs | Nov 2007 | A1 |
20080166222 | Yamashita | Jul 2008 | A1 |
20090185895 | Wieghardt | Jul 2009 | A1 |
20100034646 | Magara | Feb 2010 | A1 |
20120164005 | Alban | Jun 2012 | A1 |
20120210722 | Hynum | Aug 2012 | A1 |
Number | Date | Country | |
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20160123344 A1 | May 2016 | US |
Number | Date | Country | |
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61831655 | Jun 2013 | US |