Chiller oil distillation system and method

Abstract

A still of a chiller system includes a first inlet configured to receive a mixture of a working fluid of a vapor compression circuit and an oil leaked from an oil circuit into the vapor compression circuit, a second inlet configured to receive an additional oil from the oil circuit, and an enclosure defining an internal cavity configured to place the additional oil in a heat exchange relationship with the mixture such that the heat exchange relationship causes a separation of the working fluid from the oil.

Description

CHILLER OIL DISTILLATION SYSTEM AND METHODCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority from and the benefit of U.S. Provisional Application No. 63 / 625,744, entitled “CHILLER OIL DISTILLATION SYSTEM AND METHOD,” filed January 26, 2024, which is herein incorporated by reference in its entirety for all purposes.BACKGROUND

[0002] This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.

[0001] Chiller systems, or vapor compression systems, utilize a working fluid (e.g., a refrigerant) that changes phases between vapor, liquid, and combinations thereof in response to exposure to different temperatures and pressures within components of the chiller system. The chiller system may place the working fluid in a heat exchange relationship with a conditioning fluid (e.g., water) and may deliver the conditioning fluid to conditioning equipment and / or a conditioned environment serviced by the chiller system. In such applications, the conditioning fluid may be directed through downstream equipment, such as air handlers, to condition other fluids, such as air in a building.

[0002] The chiller system may include a compressor configured to pressurize the working fluid and circulate the working fluid through a working fluid circuit of the chiller system. For example, a shaft of the compressor may be driven in rotation by a motor in order to drive rotation of an impeller of the compressor that pressurizes the working fluid prior to delivery of the working fluid through a diffuser gap and into, for example, acollector. In certain applications, oil may be used to lubricate moving parts of the compressor and / or other componentry of the chiller system. Additionally or alternatively, the oil may be employed to dissipate heat. In certain embodiments, chiller systems may be susceptible to oil undesirably leaking into the working fluid (e.g., refrigerant), which can negatively impact lubrication, heat dissipation, chiller performance, chiller efficiency, etc. Traditional techniques for oil distillation may be inefficient and / or ineffective. Accordingly, it is now recognized that improved systems and methods are desired.SUMMARY

[0003] A summary of certain embodiments disclosed herein is set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of aspects that may not be set forth below.

[0004] In an embodiment, a chiller system includes a vapor compression circuit configured to circulate a working fluid, an oil circuit configured to circulate an oil for lubricating componentry of the vapor compression circuit, dissipating heat from the vapor compression circuit, or both, and a still. The still is configured to receive a mixture of a portion of the refrigerant and a first portion of the oil that has leaked into the vapor compression circuit. The still is also configured to receive a second portion of the oil, where the second portion of the oil includes a higher temperature than the first portion of the oil. The still is also configured to place the second portion of the oil in a heat exchange relationship with the mixture such that the heat exchange relationship causes a separation of the portion of the refrigerant from the first portion of the oil.

[0005] In another embodiment, a still of a chiller system includes a first inlet configured to receive a mixture of a working fluid of a vapor compression circuit and an oil leaked from an oil circuit into the vapor compression circuit. The still also includes a second inlet configured to receive an additional oil from the oil circuit. The still alsoincludes an internal cavity configured to place the additional oil in a heat exchange relationship with the mixture such that the heat exchange relationship causes a separation of the working fluid from the oil.

[0006] In still another embodiment, a method includes receiving, in a still, a mixture of a portion of refrigerant corresponding to a vapor compression circuit of a chiller and a first portion of an oil corresponding to an oil circuit of the chiller. The method also includes receiving, in the still and from a sump, a second portion of the oil having a higher temperature than the first portion of the oil. The method also includes establishing, in the still, a heat exchange relationship between the mixture and the second portion of the oil to cause a separation of the portion of the refrigerant from the first portion of the oil.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Various aspects of this disclosure may be better understood upon reading the following detailed description and upon reference to the drawings in which:

[0008] FIG. l is a perspective view of an embodiment of a building that may utilize a heating, ventilating, air conditioning, and / or refrigeration (HVAC&R) system in a commercial setting, in accordance with an aspect of the present disclosure;

[0009] FIG. 2 is a perspective view of an embodiment of a vapor compression system, in accordance with an aspect of the present disclosure;

[0010] FIG. 3 is a schematic view of an embodiment of the vapor compression system of FIG. 2, in accordance with an aspect of the present disclosure;

[0011] FIG. 4 is a schematic view of an embodiment of the vapor compression system of FIG. 2, in accordance with an aspect of the present disclosure;

[0012] FIG. 5 is a schematic view of an oil distillation system employable in any of the systems illustrated in FIGS. 1-4, in accordance with an aspect of the present disclosure;

[0013] FIG. 6 is a perspective view of a still for an oil distillation system, in accordance with an aspect of the present disclosure;

[0014] FIG. 7 is a cross-sectional perspective view of a still for an oil distillation system, in accordance with an aspect of the present disclosure; and

[0015] FIG. 8 is a process flow diagram illustrating an oil distillation method, in accordance with an aspect of the present disclosure.DETAILED DESCRIPTION

[0016] One or more specific embodiments will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers’ specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

[0017] When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” and “the” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to “one embodiment” or “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

[0018] As used herein, the terms “approximately,” “generally,” and “substantially,” and so forth, are intended to convey that the property value being described may be withina relatively small range of the property value, as those of ordinary skill would understand. For example, when a property value is described as being “approximately” equal to (or, for example, “substantially similar” to) a given value, this is intended to mean that the property value may be within + / - 5%, within + / - 4%, within + / - 3%, within + / - 2%, within + / - 1%, or even closer, of the given value. Similarly, when a given feature is described as being “substantially parallel” to another feature, “generally perpendicular” to another feature, and so forth, this is intended to mean that the given feature is within + / - 5%, within + / - 4%, within + / - 3%, within + / - 2%, within + / - 1%, or even closer, to having the described nature, such as being parallel to another feature, being perpendicular to another feature, and so forth. Further, it should be understood that mathematical terms, such as “planar,” “slope,” “perpendicular,” “parallel,” and so forth are intended to encompass features of surfaces or elements as understood to one of ordinary skill in the relevant art, and should not be rigidly interpreted as might be understood in the mathematical arts. For example, a “planar” surface is intended to encompass a surface that is machined, molded, or otherwise formed to be substantially flat or smooth (within related tolerances) using techniques and tools available to one of ordinary skill in the art. Similarly, a surface having a “slope” is intended to encompass a surface that is machined, molded, or otherwise formed to be oriented at an angle (e.g., incline) with respect to a point of reference using techniques and tools available to one of ordinary skill in the art.

[0019] Embodiments of the present disclosure relate to a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system (e.g., a chiller) including a vapor compression system (e.g., vapor compression circuit) having a compressor. In operation, the compressor may pressurize a working fluid within the vapor compression system and direct the working fluid to a condenser, which may cool and condense the working fluid. The condensed working fluid may be directed to an expansion device, which may reduce a pressure of the working fluid, further cooling the working fluid. From the expansion device, the cooled working fluid may be directed to an evaporator, where the working fluid may be placed in a heat exchange relationship with a conditioning fluid to cool the conditioning fluid. The conditioning fluid may be circulated between the evaporator anda structure, such as a building, where the conditioning fluid is used to cool an air flow delivered to a conditioned space of the structure. In some embodiments, an air handling unit (AHU) of the HVAC&R system may receive the conditioning fluid from the chiller and utilize the conditioning fluid to cool the air flow delivered to the conditioned space. The conditioning fluid may then be returned to the evaporator to be cooled again.

[0020] In certain applications, oil may be used to lubricate moving parts of the compressor and / or other componentry of the chiller system. Additionally or alternatively, the oil may be employed to dissipate heat. In certain embodiments, chiller systems may be susceptible to oil undesirably leaking into the working fluid (e.g., refrigerant), which can negatively impact lubrication, heat dissipation, chiller performance, chiller efficiency, etc. Oil leakage into the working fluid may be particularly likely, for example, from the compressor and into the evaporator. Traditional techniques for oil distillation may be inefficient and / or ineffective.

[0021] Accordingly, presently disclosed embodiments relate to oil distillation systems and methods. For example, presently disclosed embodiments of the oil distillation system may include a still configured to receive a mixture of a portion of refrigerant and a first portion of oil that has leaked into the vapor compression circuit (e.g., into the refrigerant). The still is also configured to receive a second portion of oil having a higher temperature than the first portion of oil. For example, in certain embodiments, the still includes a coil configured to receive the second portion of oil from a sump, where the coil is submerged in the mixture described above. In this way, the coil establishes a heat exchange relationship between the second portion of oil and the mixture. Because the portion of refrigerant and the first portion of oil in the mixture include different boiling temperatures (e.g., the portion of refrigerant includes a lower boiling temperature than the first portion of oil), the heat exchange relationship may cause a separation of the portion of refrigerant from the first portion of oil. For example, the portion of refrigerant may boil into a gaseous or vapor form that is returned to the vapor compression circuit via a refrigerant vent line in the still (referred to in certain instances of the present disclosure as a still vent line).Additionally or alternatively, an oil motive eductor (e.g., liquid-to-liquid eductor) may be configured to receive the first portion of oil (e.g., after separation from the portion of refrigerant) from the still and the second portion of oil from the coil disposed in the still, where a combination (e.g., second mixture) of the first portion of oil and the second portion of oil is biased to a sump. For example, the second portion of oil may pressurize the oil motive eductor, which causes the first portion of oil to be scavenged from a bottom of the still. In this way, the sump may receive the oil in a concentrated (e.g., pure) form without refrigerant therein.

[0022] In some embodiments, the still does not include the coil, and instead receives the second portion of oil (e.g., in a vapor or droplet form) from a sump vent line of the sump, where internal mechanisms of the still operate to maintain a separation of the second portion of oil from the portion of refrigerant (e.g., until the second portion of oil condenses and is removed from the still to the oil motive eductor).

[0023] In still other embodiments, both the coil and the sump vent line are employed to establish one or more heat exchange relationships with the mixture. For example, the coil may receive the second portion of oil and the sump vent line may bias a third portion of oil into the still. In any of the above-described embodiments, outlined in greater detail below with reference to the drawings, relatively hot oil from the sump is employed to generate one or more heat exchange relationships with the mixture, thereby causing the portion of refrigerant in the mixture to boil or evaporate. In traditional configurations not employing presently disclosed features and techniques, the relatively hot oil may simply be cooled by an oil cooler prior to returning the oil, for example, for lubrication of chiller system componentry. By employing the relatively hot oil in the heat exchange relationship(s) outlined by the present disclosure, heat that would otherwise be wasted is used to drive beneficial oil / refrigerant separation, thereby improving efficiency of the system, reducing a load on an oil cooler of the system, etc. In general, presently disclosed embodiments are configured to efficiently and effectively separate oil and refrigerant associated with a chiller system to improve chiller system performance and efficiency.These and other aspects of the present disclosure are described in detail below with reference to the drawings.

[0024] Turning now to the drawings, FIG. 1 is a perspective view of an embodiment of a heating, ventilating, air conditioning, and / or refrigeration (HVAC&R) system 10 in a building 12 for a typical commercial setting. The HVAC&R system may include a vapor compression system 14 to supply chilled liquid to cool the building 12 and a boiler 16 to supply warm liquid to heat the building 12. The vapor compression system 14, also referred to herein as a chiller, may circulate a working fluid (e.g., refrigerant) that is cooled by a cooling fluid (e.g., liquid such as water) in a condenser of the vapor compression system 14, and that is heated by a conditioning fluid (e.g., liquid, such as water) in an evaporator of the vapor compression system 14. The cooling fluid may be provided by a cooling tower which cools the cooling fluid via, for example, ambient air. The conditioning fluid, cooled by the working fluid as noted above, may be utilized to cool an air flow provided to conditioned spaces of the building 12.

[0025] The HVAC&R system 10 may also include an air distribution system which circulates air through the building 12. The air distribution system can also include an air return duct 18, an air supply duct 20, and / or an air handler 22. In some embodiments, the air handler 22 may include a heat exchanger that is connected to the boiler 16 and the vapor compression system 14 by conduits 24. The heat exchanger in the air handler 22 may receive either heated liquid from the boiler 16 or the conditioning fluid (e.g., chilled liquid such as water) from the vapor compression system 14, depending on the mode of operation of the HVAC&R system 10. The HVAC&R system 10 is shown with a separate air handler on each floor of building 12, but in other embodiments, the HVAC&R system 10 may include air handlers 22 and / or other components that may be shared between or among floors

[0026] FIGS. 2 and 3 illustrate embodiments of the vapor compression system 14, or chiller, which can be used in the HVAC&R system 10. The vapor compression system 14 may circulate a working fluid through a circuit (e.g., working fluid circuit) starting with acompressor 32, such as a centrifugal compressor. The circuit may also include a condenser 34, an expansion valve(s) or device(s) 36, and an evaporator 38. The vapor compression system 14 may further include a control panel 40 that has an analog to digital (A / D) converter 42, a microprocessor 44, a non-volatile memory 46, and / or an interface board 48.

[0027] Some examples of fluids that may be used as working fluids in the vapor compression system 14 are hydrofluorocarbon (HFC) based refrigerants, for example, R- 410A, R-407, R-134a, hydrofluoro olefin (HFO), “natural” refrigerants like ammonia (NH3), R-717, carbon dioxide (CO2), R-744, or hydrocarbon-based refrigerants, water vapor, or any other suitable working fluid. Other possible working fluids include R-123, R-514A, R-1130yd, R-1233zd, R-134a, R-1142ze, R-1142yf, R-1311, R-32, and R-410A. In some embodiments, the vapor compression system 14 may be configured to efficiently utilize working fluids having a normal boiling point of about 19 degrees Celsius (66 degrees Fahrenheit) at one atmosphere of pressure, also referred to as low pressure refrigerants, versus a medium pressure working fluid, such as R-134a. As used herein, “normal boiling point” may refer to a boiling point temperature measured at one atmosphere of pressure.

[0028] In some embodiments, the vapor compression system 14 may use one or more of a variable speed drive (VSDs) 52, a motor 50, the compressor 32, the condenser 34, the expansion valve or device 36, and / or the evaporator 38. The motor 50 may drive the compressor 32 during a normal operating mode and may be powered by a variable speed drive (VSD) 52. The VSD 52 receives alternating current (AC) power during the normal operating mode, where the AC power includes a particular fixed line voltage and fixed line frequency from an AC power source, and provides power having a variable voltage and frequency to the motor 50. In other embodiments, the motor 50 may be powered directly from an AC or direct current (DC) power source. The motor 50 may include any type of electric motor that can be powered by a VSD or directly from an AC or DC power source, such as a switched reluctance motor, an induction motor, an electronically commutated permanent magnet motor, or another suitable motor.

[0029] The compressor 32 compresses a working fluid vapor and delivers the vapor to the condenser 34 through a discharge passage. In some embodiments, the compressor 32 may be a centrifugal compressor. The working fluid vapor delivered by the compressor 32 to the condenser 34 may transfer heat to a cooling fluid (e.g., water or air) in the condenser 34. The working fluid vapor may condense to a working fluid liquid in the condenser 34 as a result of thermal heat transfer with the cooling fluid. The liquid working fluid from the condenser 34 may flow through the expansion device 36 to the evaporator 38. In the illustrated embodiment of FIG. 3, the condenser 34 is water cooled and includes a tube bundle 54 connected to a cooling tower 56, which supplies the cooling fluid to the condenser 34.

[0030] The liquid working fluid delivered to the evaporator 38 may absorb heat from a conditioning fluid that is subsequently routed to a load 62 (e.g., the building 12 of FIG. 1). For example, the conditioning fluid may be cooled by the working fluid in the evaporator 38, and then may be utilized in the building 12 of FIG. 1 to condition an air flow provided to condition a space in the building 12. The liquid working fluid in the evaporator 38 may undergo a phase change from the liquid working fluid to a working fluid vapor. As shown in the illustrated embodiment of FIG. 3, the evaporator 38 may include a tube bundle 58 having a supply line 60S and a return line 60R connected to the load 62 (e.g., cooling load). The conditioning fluid of the evaporator 38 (e.g., water, ethylene glycol, calcium chloride brine, sodium chloride brine, or any other suitable fluid) enters the evaporator 38 via return line 60R and exits the evaporator 38 via supply line 60S. The evaporator 38 may reduce the temperature of the conditioning fluid in the tube bundle 58 via thermal heat transfer with the working fluid. The tube bundle 58 in the evaporator 38 can include a plurality of tubes and / or a plurality of tube bundles. In any case, the vapor working fluid exits the evaporator 38 and returns to the compressor 32 by a suction line to complete the cycle.

[0031] FIG. 4 is a schematic of an embodiment of the vapor compression system 14 with an intermediate circuit 64 incorporated between the condenser 34 and the expansiondevice 36. The intermediate circuit 64 may have an inlet line 68 that is directly fluidly connected to the condenser 34. In other embodiments, the inlet line 68 may be indirectly fluidly coupled to the condenser 34. As shown in the illustrated embodiment of FIG. 4, the inlet line 68 includes a first expansion device 66 positioned upstream of an intermediate vessel 70. In some embodiments, the intermediate vessel 70 may be a flash tank (e.g., a flash intercooler). In other embodiments, the intermediate vessel 70 may be configured as a heat exchanger or a "surface economizer." In the illustrated embodiment of FIG. 4, the intermediate vessel 70 is used as a flash tank, and the first expansion device 66 is configured to lower the pressure of (e g., expand) the liquid working fluid received from the condenser 34. During the expansion process, a portion of the liquid working fluid may vaporize, and thus, the intermediate vessel 70 may be used to separate the vapor working fluid from the liquid working fluid received from the first expansion device 66. Additionally, the intermediate vessel 70 may provide for further expansion of the liquid working fluid due to a pressure drop experienced by the liquid working fluid when entering the intermediate vessel 70 (e.g., due to a rapid increase in volume experienced when entering the intermediate vessel 70). The vapor working fluid in the intermediate vessel 70 may be drawn by the compressor 32 through a suction line 74 of the compressor 32. In other embodiments, the vapor working fluid in the intermediate vessel 70 may be drawn to an intermediate stage of the compressor 32 (e.g., not the suction stage). The liquid working fluid that collects in the intermediate vessel 70 may be at a lower enthalpy than the liquid working fluid exiting the condenser 34 due to expansion of the working fluid at the expansion device 66 and / or in the intermediate vessel 70. The liquid working fluid from intermediate vessel 70 may then flow through line 72 and through a second expansion device 36 to the evaporator 38.

[0032] In certain systems and / or conditions, oil employed to lubricate componentry (among other possible technical uses) of any of the systems illustrated in FIGS. 1-4 may leak into a working fluid (e g., refrigerant) circuit, or vapor compression circuit, of such system(s). In accordance with present embodiments, an oil distillation system is employed to separate the oil from the refrigerant. For example, the oil distillation system mayestablish one or more heat exchange relationships between one or more flows of relatively hot oil and a mixture of the oil and the refrigerant. Because the oil and the refrigerant of the mixture include different boiling temperatures (e.g., the refrigerant includes a lower boiling temperature than the oil), the one or more heat exchange relationships may cause a separation of the oil and the refrigerant (e.g., may cause the refrigerant of the mixture to boil or evaporate). The separated refrigerant (e.g., in gaseous or vapor form) may be vented and returned to the working fluid (e.g., refrigerant) circuit, and the oil may be returned to an oil sump (e.g., by way of an oil motive, liquid-to-liquid eductor). By establishing the heat exchange relationship(s) via the relatively hot oil, heat in the relatively hot oil is not wasted, an efficiency of the system is improved, and the oil is effectively separated from the working fluid (e.g., refrigerant). These and other aspects of the present disclosure are described in greater detail with reference to FIGS. 5-8 below.

[0033] FIG. 5 is a schematic view of an embodiment of an oil distillation system 90 employable in any of the systems illustrated in FIGS. 1-4. In the illustrated embodiment, the oil distillation system 90 includes a still 92 configured to receive a mixture 94 of a portion of refrigerant corresponding to a vapor compression circuit of a chiller system and a first portion of oil corresponding to an oil circuit of the chiller. For example, the still 92 may receive all or most the mixture 94 from an evaporator of the vapor compression circuit via a gravity feed line 95. A solenoid valve 96 between the evaporator and the still 92 may be controlled to enable or disable a flow of the mixture 94 to the still 92. In some embodiments, the solenoid valve 96 is controlled to enable the flow of the mixture 94 to the still 92 in response to one or more operating characteristics of the system, such as a temperature of a fluid (e g., oil, refrigerant, or mixture thereof), a determination that a threshold amount of the oil has leaked into the vapor compression circuit, etc. In other embodiments, the solenoid valve 96 is controlled periodically (e.g., based on a schedule) to enable the flow of the mixture 94 to the still 92. Further, an additional portion of the mixture 94 may be received at the still 92 from a gas motive eductor 93, which receives a discharge gas 97 that pressurizes the gas motive eductor 93 to receive fluid from the main compressor PRV drain 99 (e.g., from the compressor plenum).

[0034] The mixture 94 may be gravity fed to the still 92 and, more particularly, to a bottom area of the still 92 in which a coil 98 is disposed. In this way, the coil 98 may be submerged (e.g., entirely or partly) in the mixture 94. As shown, the coil 98 is configured to receive a second portion of oil 100 (e.g., relatively hot oil) from, for example, a high pressure oil feed line 101 extending from an oil sump 102 to the coil 98 in the still 92, where the oil sump 102 is fed oil from oil drains 103a, 103b corresponding to the main compressor and auxiliary compressor of the chiller system. A pump 104 (e.g., main compressor oil pump) in the oil sump 102 may be configured to pressurize and bias the second portion of oil 100 toward and through the coil 98 in the still 92. However, some (e.g., most) of the second portion of oil 100 may be routed to an oil cooler assembly 105 (e.g., corresponding to the main compressor of the chiller system).

[0035] The coil 98 may establish a heat exchange relationship between the second portion of oil 100 and the mixture 94 in which the coil 98 is submerged. Because the first portion of oil in the mixture 94 includes a higher boiling temperature than the portion of refrigerant in the mixture 94, and based on a temperature of the second portion of oil 100 in the coil 98, the heat exchange relationship may cause the portion of refrigerant in the mixture 94 to boil or evaporate (e.g., while the first portion of oil in the mixture 94 remains in liquid phase). In this way, a gaseous or vapor phase of the portion of refrigerant in the mixture 94 may be vented from the still 92 via a still vent line 106, as shown in FIG. 5.

[0036] Additionally or alternatively, a sump vent line 108 extending from the oil sump 102 and to the still 92 may provide another (e.g., third) portion of oil 110 to the still 92. For example, the third portion of oil 110 may be in vapor or droplet form, and may be employed to further heat the mixture 94 and / or constituents thereof. In some embodiments, internal mechanisms of the still 92, including but not limited to an internal cylinder 111 (described in greater detail with reference to FIGS. 6 and 7), may be employed to maintain fluid separation of the third portion of oil 1 10 from the gaseous or vapor phase of the portion of refrigerant boiled (e.g., evaporated) off the mixture 94.

[0037] In some embodiments, the coil 98 is employed without the sump vent line 108, while in other embodiments, the sump vent line 108 is employed without the coil 98. Accordingly, it should be understood that “first portion,” “second portion,” and / or “third portion” of the oil are relative terms and need not all be present in a given embodiment. For example, in embodiments employing the coil 98 but not the sump vent line 108, the portion of oil 100 corresponding to the coil 98 may be referred to as a “second portion,” while in embodiments employing the sump vent line 108 but not the coil 98, the portion of oil 110 corresponding to the sump vent line 108 may be referred to as a “second portion.” Of course, both the coil 98 and the sump vent line 108 may be employed in certain embodiments, as shown in FIG. 5.

[0038] As previously described, the gaseous or vapor phase of the portion of refrigerant may be vented from the still 92 via the still vent line 106. Additionally, an oil motive eductor 112 (e.g., liquid-to-liquid eductor) may be configured to receive a first portion of oil 114 (e.g., from the mixture 94) and the second portion of oil 100 corresponding from the coil 98. More particularly, the second portion of oil 100 pressurizes the oil motive eductor 112, thereby scavenging the first portion of oil 114 (e.g., from the mixture 94) toward the oil motive eductor 112. In addition to the portion of refrigerant in the mixture 94 being boiled or evaporated and vented from the still 92 as previously described, the portion of refrigerant may be prevented from reaching the oil motive eductor 112 based on disparate densities between the oil and the refrigerant. In this way, oil in concentrated or pure form is routed back to the oil sump 102 via the oil motive eductor 112. That is, a combination (e.g., additional mixture) of the first portion of oil 114 and the second portion of oil 100 is output by the oil motive eductor 112 (e.g., eductor discharge 116) and routed to the oil sump 102.

[0039] In some embodiments, the oil sump 102 includes an auxiliary pump 118 (e.g., auxiliary compressor oil pump) configured to bias oil to an auxiliary oil cooler assembly 120 (e.g., corresponding to an auxiliary compressor of the chiller system). As previously described, utilizing the coil 98 and / or sump vent line 108 may cool at least some of the oilin the system by rejecting heat from the oil to the mixture 94. In this way, the oil distillation system 90 effectively and efficiently separates the oil from the refrigerant in the mixture 94 while reducing a load on the oil cooler assembly 105 and / or the auxiliary oil cooler assembly 120. Further, use of the oil motive eductor 112 may be a more efficient and effective means for moving oil from the still 92 and to the oil sump 102 than traditional mechanisms (e.g., gas eductors employing refrigerant flow).

[0040] FIG. 6 is a perspective view of an embodiment of the still 92 for an oil distillation system, such as (but not limited to) the oil distillation system 90 illustrated in FIG. 5. Further, FIG. 7 is a cross-sectional perspective view of an embodiment of the still 92. As shown in FIG. 6, the still 92 includes an enclosure 130, a still vent line flange 132 coupled to (or forming a part of) the enclosure 130 (e.g., corresponding to the still vent line 106 illustrated in FIG. 5), and an oil sump vent line flange 134 (e.g., corresponding to the sump vent line 108 in FIG. 5). Further, the still 92 includes a high pressure oil feed inlet 136 (e.g., coupled to the coil 98 in FIG. 5), a high pressure oil feed outlet 138 (e.g., coupled to the coil 98 in FIG. 5), a concentrated oil outlet 140 (e.g., outputting the first portion of oil 114 to the oil motive eductor 112 in FIG. 5), an oil laden refrigerant inlet 144 (e g., corresponding to the gravity feed line 95 and solenoid valve 96 illustrated in FIG. 5), a temperature thermistor 142 or sensor (e.g., employed to control the solenoid valve 96 in FIG. 5), and a PRV eductor port 146 (e.g., corresponding to the gas motive eductor 93 in FIG. 5).

[0041] The embodiment of the still 92 illustrated in FIG. 7 may include the same or similar features referenced above with respect to FIG. 6 (although the oil laden refrigerant inlet 144 and the PRV eductor port 146 are not shown due to the illustrated perspective and cross-section). Also shown in FIG. 7, but hidden from view in FIG. 6, is the coil 98 of the still 92, the internal cylinder 111 disposed in the enclosure 130, an additional internal cylinder 148 disposed in the enclosure 130 radially inwards from the internal cylinder 111 , and a ledge 150 coupled to an inner surface 151 of the enclosure 130 and extending radially toward the internal cylinder 111. As shown, the internal cylinder 111 includes a meshcoalescer 152 adjacent to the coil 98 and one or more windows 154 (or “cutouts”) adjacent to an upper portion 158 (or “lid) of the enclosure 130 and extending circumferentially about the internal cylinder 111.

[0042] In addition to hot oil being biased through the coil 98, as previously described, hot oil may enter an internal cavity 160 defined by the enclosure 130 of the still 92 through the oil sump vent line flange 134 (e.g., oriented tangentially along the enclosure 130) by utilizing an impingement method to bias the larger droplets of hot oil against the inner surface 151 of the enclosure 130. A fanning effect causes the hot oil to spread circumferentially about the inner surface 151, where the ledge 150 (e.g., outer annulus or “deflector”) may operate to prevent the larger hot oil droplets from rising too far upwardly along the inner surface 151. The ledge 150 may also operate to create a low pressure in a first chamber 162 (e.g., upper chamber, low pressure chamber) of the internal cavity 160. That is, the first chamber 162 of the internal cavity 160 may be disposed above the ledge 150 and a second chamber 163 of the internal cavity 160 may be disposed below the ledge 150 (e.g., where the first chamber 162 and the second chamber 163 are in fluid communication via a gap 165 between the ledge 150 and the internal cylinder 111). Further, surface tension tends to keep the larger hot oil droplets on the inner surface 151 as they are gravity fed downwardly toward the coil 98 (e.g., the bottom of the internal cavity 160).

[0043] Smaller hot oil droplets received via the oil sump vent line flange 134 may be suspended in vapor between the inner surface 151 of the enclosure 130 and the internal cylinder 111. The mesh coalesce 152 may operate to block the smaller hot oil droplets from immediately entering into the internal cylinder 111, causing the smaller hot oil droplets to form larger hot oil droplets, which then ride or wick into the refrigerant gas flow along an inner surface 164 of the internal cylinder 111. However, the windows 154 (or “cutouts”) in the internal cylinder 11 1 enable these hot oil droplets to fall into the first chamber 162 defined in the internal cavity 160 above the ledge 150, which ultimately travel downwardly (e.g., through the gap 165 and into the second chamber 163) back toward thecoil 98. In this way, oil is prevented from climbing into the additional internal cylinder 148, which is employed (as previously described) to vent the refrigerant gas through the still vent line corresponding to the still vent line flange 132 illustrated in FIGS. 6 and 7.

[0044] FIG. 8 is a process flow diagram illustrating an embodiment of an oil distillation method 200. An ordering of the steps of the method 200, described in detail below, should not be taken to necessarily imply a chronology of the steps of the method 200. While the steps of the method 200 may be representative of a chronological order in one embodiment, other orders are also possible in certain embodiments.

[0045] In the illustrated embodiment, the method 200 includes receiving (block 202), in a still, a mixture of a portion of refrigerant corresponding to a vapor compression circuit of a chiller and a first portion of an oil corresponding to an oil circuit of the chiller. For example, the first portion of the oil may leak into the vapor compression circuit and mix with the portion of the refrigerant. The mixture of the portion of the refrigerant and the first portion of the oil is moved to a cavity of the still for distillation.

[0046] The method 200 also includes receiving (block 204), in the still and from a sump, a second portion of the oil having a higher temperature than the first portion of the oil. For example, in certain embodiments, the still may include a coil submerged in the abovedescribed mixture and configured to receive the second portion of the oil, which may be biased to and through the coil via a pump associated with the sump. Additionally or alternatively, in certain embodiments, the still may receive the second portion of the oil in vapor or droplet form via a sump vent line coupled between the sump and the still. The method 200 also includes establishing (block 206), in the still, a heat exchange relationship between the mixture and the second portion of the oil to cause a separation of the portion of the refrigerant from the first portion of the oil. For example, the second portion of the oil (e.g., in the coil and / or biased to the still via the sump vent line) may be relatively hot (e.g., following use as a lubricant and / or heat dissipator with respect to componentry of the chiller). Because the first portion of the oil in the mixture includes a higher boiling temperature than the portion of the refrigerant in the mixture, a heat exchange relationshipestablished between the mixture and the second portion of the oil causes the portion of the refrigerant in the mixture to boil. In some embodiments, the second portion of the oil may be referred to as second and third portions of oil (e.g., where one corresponds to the coil and the other corresponds to the sump vent line).

[0047] Although not included in the illustrated embodiment, the method 200 may also include venting the portion of the refrigerant (e.g., after separation from the first portion of the oil) from the still and toward the vapor compression circuit (e.g., the main compressor PRV plenum). Additionally or alternatively, the method 200 may include employing an oil motive eductor (e.g., liquid-to-liquid eductor) to receive the first portion of the oil (e.g., in pure or concentrated form, after separation from the portion of the refrigerant) and the second portion of the oil from the coil, and to bias a combination (e.g., additional mixture) of the first portion of the oil and the second portion of the oil toward and into the sump.

[0048] While only certain features and embodiments have been illustrated and described, many modifications and changes may occur to those skilled in the art, such as variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, such as temperatures and pressures, mounting arrangements, use of materials, colors, orientations, and so forth, without materially departing from the novel teachings and advantages of the subject matter recited in the claims. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the disclosure.

[0049] Furthermore, in an effort to provide a concise description of the exemplary embodiments, all features of an actual implementation may not have been described, such as those unrelated to the presently contemplated best mode, or those unrelated to enablement. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation specific decisions may be made. Such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacturefor those of ordinary skill having the benefit of this disclosure, without undue experimentation.

[0050] The techniques presented and claimed herein are referenced and applied to material objects and concrete examples of a practical nature that demonstrably improve the present technical field and, as such, are not abstract, intangible or purely theoretical. Further, if any claims appended to the end of this specification contain one or more elements designated as “means for [perform]ing [a function], ..” or “step for [perform]ing [a function]...”, it is intended that such elements are to be interpreted under 35 U.S.C. 112(f). However, for any claims containing elements designated in any other manner, it is intended that such elements are not to be interpreted under 35 U.S.C. 112(f).

Claims

CLAIMS:

1. A chiller system, comprising: a vapor compression circuit configured to circulate a working fluid; an oil circuit configured to circulate an oil for lubricating componentry of the vapor compression circuit, dissipating heat from the vapor compression circuit, or both; and a still configured to: receive a mixture of a portion of the working fluid and a first portion of the oil that has leaked into the vapor compression circuit; receive a second portion of the oil, wherein the second portion of the oil includes a higher temperature than the first portion of the oil; and place the second portion of the oil in a heat exchange relationship with the mixture such that the heat exchange relationship causes a separation of the portion of the working fluid from the first portion of the oil.

2. The chiller system of claim 1, wherein the still comprises a coil configured to be submerged in the mixture and to receive the second portion of the oil.

3. The chiller system of claim 1, comprising a sump configured to receive the first portion of the oil from the still after the separation of the portion of the working fluid from the first portion of the oil.

4. The chiller system of claim 3, comprising an oil motive eductor positioned between the still and the sump, wherein the oil motive eductor is configured to: receive the first portion of the oil downstream from the still and upstream of the sump; and receive the second portion of the oil from a coil in the still.

5. The chiller system of claim 4, wherein the sump is configured to receive an additional mixture of the first portion of the oil and the second portion of the oil from the oil motive eductor.

6. The chiller system of claim 3, comprising a sump vent line extending from the sump and to the still, wherein the sump vent line is configured to provide the second portion of the oil to the still.

7. The chiller system of claim 3, comprising: a coil of the still, wherein the coil is configured to be submerged in the mixture and to receive the second portion of the oil such that the coil establishes the heat exchange relationship; and a sump vent line extending from the sump and to the still, wherein the sump vent line is configured to provide a third portion of the oil from the sump and to the still.

8. The chiller system of claim 1, comprising a still vent line configured to: receive the portion of the working fluid after the separation of the portion of the working fluid from the first portion of the oil; and bias the portion of the working fluid toward the vapor compression circuit.

9. A still of a chiller system, comprising: a first inlet configured to receive a mixture of a working fluid of a vapor compression circuit and an oil leaked from an oil circuit into the vapor compression circuit; a second inlet configured to receive an additional oil from the oil circuit; and an enclosure defining an internal cavity configured to place the additional oil in a heat exchange relationship with the mixture such that the heat exchange relationship causes a separation of the working fluid from the oil.

10. The still of claim 9, comprising a coil disposed in the internal cavity and coupled to the second inlet such that the coil is submerged in the mixture and receives the additional oil.

11. The still of claim 10, comprising: an internal cylinder disposed in the internal cavity above the coil; and a mesh coalescer disposed in the internal cylinder.

12. The still of claim 1 1, comprising: a ledge extending from an inner surface of the enclosure and toward the internal cylinder such that a first chamber of the internal cavity resides on a first side of the ledge and a second chamber of the internal cavity resides on a second side of the ledge opposing the first side of the ledge; and at least one cutout in the internal cylinder adjacent to the first chamber of the internal cavity.

13. The still of claim 12, comprising a vent line extending into the internal cylinder.

14. A method, comprising: receiving, in a still, a mixture of a portion of a refrigerant corresponding to a vapor compression circuit of a chiller and a first portion of an oil corresponding to an oil circuit of the chiller; receiving, in the still and from a sump, a second portion of the oil having a higher temperature than the first portion of the oil; and establishing, in the still, a heat exchange relationship between the mixture and the second portion of the oil to cause a separation of the portion of the refrigerant from the first portion of the oil.

15. The method of claim 14, comprising receiving the second portion of the oil from the sump in a coil disposed in the still and submerged in the mixture.

16. The method of claim 15, comprising: receiving, in an oil motive eductor, the first portion of the oil after the separation of the portion of the refrigerant from the first portion of the oil; and receiving, in the oil motive eductor and from the coil, the second portion of the oil.

17. The method of claim 16, comprising receiving an additional mixture of the first portion of the oil and the second portion of the oil from the oil motive eductor and in the sump.

18. The method of claim 15, comprising receiving a third portion of the oil in the still via a sump vent line extending from the sump to the still.

19. The method of claim 14, comprising receiving the second portion of the oil via a sump vent line extending from the sump to the still.

20. The method of claim 14, comprising discharging, via a still vent line, the portion of the refrigerant after the separation of the portion of the refrigerant from the first portion of the oil.

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