Vertical oil separator

Abstract

A vertical oil separator for separating oil from a refrigerant gas and oil mixture on the high side of a refrigeration/chiller system comprising, a vertical housing having an upper chamber with a cylindrical sidewall and tangentially oriented inlet for the refrigerant gas and oil mixture, said upper chamber having a refrigerant gas outlet therefrom, said housing also having a lower chamber below the upper chamber with an oil outlet therefrom, a baffle constructed and arranged in said housing to define said upper and lower chamber, at least one oil filter in said upper chamber for removing oil out of the mixture and transferring such oil downwardly from the upper chamber.

Description

FIELD OF THE INVENTION

The present invention relates generally to the commercial and industrial refrigeration art. More particularly, the invention is directed to improvements in vertical oil separators for efficiently separating oil and refrigerant gas on the high side of a refrigeration system.

BACKGROUND OF THE INVENTION

The maintenance of lubricating oil in a refrigeration system compressor is critical to its efficient operation and life span. Clearly the compressor is the principal driving force in any refrigeration or chiller system—it compresses refrigerant gas and discharges it on its high pressure side to a condenser in which the gas is condensed to a liquid phase, and thence it passes to an evaporator or like cooling coil through an expansion device reducing the refrigerant's pressure and permitting absorption of heat and expanding the liquid phase gas back to a gaseous phase on the low suction side of the compressor. All types of compressors—reciprocating, screw, scroll, centrifugal—employed in refrigeration systems use oil as a lubricant and sealant, and during operation some amount of this oil is entrained in the hot compressed refrigerant vapor discharged on the high side out to the system.

It is clear that the lubricating oil serves no useful purpose outside the compressor. Oil does not have as good heat transfer capability as the refrigerant and will reduce the efficiency of the condenser and evaporator functions. Although some amount of oil is generally present throughout the system, it is important to return most of it back to the compressor for its safe and efficient operation and to prevent oil from building up in other system components. The importance of good compressor lubrication cannot be overemphasized; and it may be noted that a typical screw compressor, for instance, may require several gallons of oil per minute.

In the past, high side oil traps or separators have been employed to separate out oil from the refrigerant gas in route from the compressor to the condenser. Such oil separators, as discussed in U.S. Pat. Nos. 4,478,050; 4,506,523; 5,133,671; and 5,271,245, are known for separating oil from the high side refrigerant gas and oil mixture, but these and other prior oil separators are deficient in performance, cost, size, system complexity and other limiting factors.

Thus it is important to provide an oil separator that provides distinctive improvements in efficient oil separation performance, simplicity of design for manufacturing cost reduction and for installation and maintenance ease.

SUMMARY OF THE INVENTION

The invention is embodied in a vertical oil separator for separating oil from a refrigerant gas and oil mixture on the high side of a refrigeration/chiller system comprising a vertical housing having an upper oil separation chamber with a cylindrical side wall and a tangentially oriented inlet for the refrigerant gas and oil mixture, said upper chamber having a refrigerant gas outlet therefrom, the housing also having a lower oil collection chamber below the upper chamber with an oil outlet therefrom, a baffle constructed and arranged in the housing between the upper and lower chambers, and a filter device in the upper chamber for entrapping oil out of the mixture and transferring such oil downwardly from the upper chamber past the baffle into the lower chamber.

The principal object of the invention is to provide an oil separation system having a highly efficient oil-refrigerant separator section and a liquid oil reservoir section. Thus, in one aspect of the invention an oil and gas mixture inlet is tangentially arranged in an upper separation section to impart a swirling action impinging the mixture by centrifugal force against and through a screen liner to remove the oil, a refrigerant gas outlet is centrally positioned in the upper section and a transverse baffle forms a division of the upper section from a lower oil accumulation reservoir, the baffle effectively restricts centrifugal vortex action to the upper section while keeping the lower oil collection reservoir relatively static and is arranged to provide a nonrestricting passageway for oil flow from the upper section to the lower section, and an oil outlet is provided for removing oil from the lower section.

Another object is to provide an efficient, easily serviced and economic oil system for a compressor driven refrigeration/chiller system. Thus, in another aspect of the invention the incoming high pressure oil-refrigerant gas mixture is given a high degree of centrifugal action to separate out the oil on a collection device in an upper inlet section, and such turbulent action is substantially eliminated from a lower liquid oil accumulator section by a dividing baffle

In another aspect, the oil separator invention provides an upper oil-gas mixture separation section with a tangential inlet to impart centrifugal action, an oil collection and transfer device has primary and secondary components to separate oil from the refrigerant gas and transfer it in liquid form, a centrally-disposed gas outlet removes refrigerant; a lower oil accumulator section receives liquid oil from the primary and secondary collection members; and a baffle between the upper and lower sections and restricts turbulent centrifugal action to the upper section while accommodating unrestricted oil flow to the lower section.

In another aspect of the invention the oil separation invention is embodied in an oil receiving mesh of substantial-thickness impacted against by incoming oil-laden refrigerant and being arranged to accumulate and hold oil in liquid form without re-entrainment back into the refrigerant discharge vapor.

These and other objects and advantages will become more apparent hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

For illustration purposes, together with the accompanying written disclosure, the invention is embodied in the parts and the combinations and arrangements of parts hereinafter described. In the drawings, wherein like numerals refer to like parts wherever they occur:

FIG. 1 is a diagrammatic view of a basic refrigeration or chiller system incorporating the invention;

FIG. 2 is an enlarged cross-sectional side view showing one embodiment of a vertical oil separator embodying the invention;

FIG. 3 is a cross-sectional view thereof taken along line 3-3 of FIG. 2;

FIG. 4 is a cross-sectional view thereof taken along line 4-4 of FIG. 2;

FIG. 5 is an enlarged side view similar to FIG. 2, but showing a second embodiment of the vertical oil separator;

FIG. 6 is a cross-sectional view of the second embodiment taken along line 6-6 of FIG. 5;

FIG. 7 is a greatly enlarged fragmentary view, partly broken away, illustrating the second embodiment and taken along line 7-7 of FIG. 5;

FIG. 8 is an enlarged cross-sectional side view showing a further embodiment of the invention;

FIG. 9 is a view similar to FIG. 8, showing a simplified version of that embodiment; and

FIG. 10 is a cross-sectional view of still another embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

For the purposes of disclosure, a closed refrigeration or chiller system 10 includes a compressor 12 connected on its high pressure outlet side to a condenser 14 through an oil separator 16 embodying the invention to be described. Typically the compressor 10 requires a large amount of lubricating and cooling oil in operation, and such oil is entrained in the hot compressed refrigerant to form an oil-gas mixture that is discharged on the compressor high side through conduit 17 to the oil separator inlet 18. It has been reported that the oil content in the oil and refrigerant gas mixture from a chiller system compressor is over 50,000 ppm (parts per million). The compressor 12 is also in fluid communication with the oil separator 16 through an oil return conduit 19 from oil outlet 20 through which oil is returned to and maintained in the compressor at a preselected level by a conventional oil level regulator (not shown) or the like. The condenser 14 is connected in fluid communication with the oil separator 16 through a refrigerant gas conduit 21 from the gas outlet 22. The hot compressed refrigerant gas (and a minor, acceptable amount of entrained oil) passes through conduit 21 to condenser 14 in which it is cooled and condensed into a high pressure liquid phase. The condenser 14 connects through conduit 23 to an evaporator 24 or like heat exchanger through an expansion valve 26. Refrigerant liquid is caused to expand and absorb heat to provide refrigeration: in a chiller system this heat exchange takes place between the expanding liquid refrigerant and a chilled liquid whereas in a typical commercial refrigeration system the expanding refrigerant absorbs heat from a circulating airflow that cools a space or product zone. In either case the refrigerant liquid absorbs latent heat and changes to a gaseous phase, and is returned to the compressor 12 on its low side through suction conduit 27 to complete the refrigeration cycle.

Referring now to FIGS. 2-4, in its simplest form the oil separator 16 has an elongated vertical main housing 30 having a generally cylindrical outer wall 31 with an upper end cap 32 and a lower end cap 33 and forming a closed vessel. An upper section 34 of the vessel forms an upper vapor receiving and oil separating chamber having vertically contiguous upper, intermediate and lower zones 35a, 35b and 35c, respectively. An inlet conduit 36 from inlet 18 is tangentially positioned in the upper zone 35a of the separator chamber and has a beveled or angled discharge opening 37 facing toward the adjacent inner surface 38 of the wall 31 to create an optimum circulating flow path and centrifugal vortex action of the oil-refrigerant vapor mixture entering the upper section 34. An oil separating and collecting member 39 in the form of a cylindrical screen or like open mesh, wire cloth member is disposed next to the inner wall surface 38, and, in this embodiment, extends vertically through the length of the upper chamber 35. Preferably this screen member 39 is about 20 mesh steel wire cloth with a 0.016 wire diameter or the like that provides a large surface to induce adherence of oil particles. In short, the oil-gas mixture enters the upper chamber zone 35(a) at a high velocity and head pressure creating a spinning circular flow path with vortex action that impinges against this first oil filtering screen liner 39 in which oil particles are pushed into and forced through the screen mesh. Thus, oil particles accumulate on and through the screen member 39 and build up in liquid form to drain downwardly along the inner wall surface 38.

A refrigerant vapor outlet conduit 41 is centrally disposed within the upper section 34 and connects to the outlet 22 in the refrigerant circuit to the condenser 14. As shown best in FIG. 2, this discharge outlet conduit has a gas intake end 42 positioned in the intermediate zone 35b substantially below the level of the oil-gas mixture inlet conduit 36 to thereby provide a substantial vertical expanse of the oil filtering screen liner 39 thereabove to optimize oil removal by centrifugal action as the refrigerant vapor circles downwardly to and below the intake level (42) of the refrigerant gas outlet conduit 41. Another or final screen filter 43 may be attached to cover the intake end 42 of the outlet conduit 41 within the circulating flow path to thereby enhance final oil separation from the refrigerant gas even at reduced compressor operating capacities.

The main housing 30 of the oil separator 16 also defines a lower oil collection section 44 forming a reservoir chamber 45 for accumulating and storing a supply of liquid oil to be returned, as needed, through oil outlet 20 to the compressor 12. Turbulence of the oil in the reservoir 45 is not desirable, and it is therefore important to render this lower chamber substantially static. To this end, a divider wall or baffle member 47 is vertically disposed in the vessel and the lower zone 35c of the upper chamber or section 34 forms a separation zone between the upper and lower sections 34 and 44. This baffle member 47, in one form, is an upwardly-domed, circular, dish-shaped wall 48 with a downwardly extending peripheral flange 49 and being constructed and arranged to form an effective barrier that restricts the turbulent circular vapor flow action to the upper section 34, and primarily the upper and intermediate zones 35a, 35b thereof, while accommodating the free downward passage of liquid oil from the upper section 34 to the lower oil collecting section 44. As shown in FIGS. 2-4, the baffle 47 is asymmetrically mounted in the main housing with its flange wall 49 attached at one side, as by interior welding 50, to the inner side wall 38. The baffle may be attached by bolts, rivets or the like if sealed to maintain the internal integrity of the high pressure vessel housing against leakage. This off-center disposition results in a larger and unrestricted oil passageway 51 being formed between the flange wall 49 and vessel wall 38 on the opposite side—the passageway 51 thence narrowing in a closing arc, around the flange periphery to the welded attachment edge of the baffle (at 50). Additional oil drain holes 52 may be provided in the upwardly domed wall surface 40 at the flange attachment point to prevent any entrapment of oil by the baffle member 47. The oil separator 16 may also be provided with an oil reservoir sight glass (not shown) mounted at upper and lower ports 53.

From the foregoing it will be seen that the oil separator unit of the present invention is simple in design; but highly efficient. One feature of novelty resides in the oil filtration device having a screen collection member 39 constructed and arranged to enhance the passage of oil particles therethrough while having a sufficient body depth and surface structure to hold or entrap the oil particles as they are pushed through by the pressurized gas vortex, and at least one other oil filter device (e.g. final screen filter 43) for providing optimum oil removal from the refrigerant gas upstream of its outlet 42 from the upper chamber. Thus, the oil particles amass and form a liquid oil curtain flowing down the inner chamber wall surface 38 to and around the baffle 47. Another feature is the offset, asymmetrical arrangement of the baffle that accommodates free oil passages therepast into the lower oil collection reservoir 45 and keeps it static by blocking and restricting gas turbulence to the upper section 34.

Referring to FIGS. 5-7, a presently preferred embodiment of the oil separator 116 is shown with common features to that of FIG. 2 identified in the “100” numerical series. In the FIG. 5 embodiment, screen liner member 139, has a primary outer layer 140a of screen material in adjacent circumscribing relationship with the inner wall surface 138 and a secondary inner layer 140b of screen material on the inside of the outer layer 140a. Thus, a multi-ply or double layer wrapping of screen mesh lines the inner wall surface 138 and provides an oil collection member of substantial oil holding thickness. The oil-laden refrigerant vapor from the compressor discharge side 17 enters the oil separator 116 through inlet tube 136 and is directed from the beveled discharge opening 137 against the dual mesh liner 140a, 140b at the upper zone 135a of the upper oil separating section 134. The flow of higher pressure oil-gas vapor impinges against the inwardly exposed surface of the inner screen layer 140b, and oil particles are thus pushed into and through the openings or perforations of the screen mesh and amass as a flowable liquid on both oil filtering layers 140a, 140b and on the inner wall surface 138 of the upper chamber wall. It appears that the bulk of the oil separation will occur in the upper and intermediate zones 135a, 135b of the upper section 134, above and at the level of the gas discharge inlet 142, and the swirling centrifugal action of the less dense (oil-lightened) refrigerant vapor against the inner screen surface and acting through the dual liner-layers keeps the body of accumulated liquid oil intact and flowing downwardly to the baffle 147 and through the oil passageway 151 into the lower section 144. A final screen filter 143 (as in FIG. 2) may be provided.

Referring to FIG. 8, in a further embodiment of the invention, the multi-ply screen mesh (239) of the oil separator 216 is modified from the embodiment of FIG. 5. In FIG. 8, the outer primary screen member 240a is substantially the same, and is formed as a cylinder of material lining the inner wall surface 238 of the main housing wall 231 and extending from the top closure cap 232 downwardly to the baffle 247 separating the upper and lower chambers 234 and 244. The inner secondary screen member 240b has a cylindrical upper section (identified generally at 260) defining the vertical extent of the upper zone 235a and being arranged in close association within the outer liner member 240a and concentric therewith. The lower section of the inner screen member (240b) is constructed to form an elongated, downwardly narrowing, funnel 262 in the intermediate or midsection (235b) of the oil separation section 234. This funnel 262 extends below the refrigerant gas discharge outlet 242 and forms a secondary oil filter. In operation, the upper section 260 of the dual screen liner 239 forms the primary upper zone 235a of oil removal—the high pressure oil-gas vapor entering the upper oil separation chamber 235 impinges against the inner screen layer 240b and oil particles are thus pushed into and through the screen mesh and accumulate in liquid form. As has been seen, the high pressure refrigerant gas continues to swirl downwardly through this uppermost separation zone pushing outwardly and maintaining an oil separation action throughout this zone while inducing liquid oil to flow downwardly along the outer screen liner 240a and the main housing wall 238. The conically tapering funnel member 262 in the midsection 235b of the upper section 234 will continue to receive and hold a layer of oil that will act to constrict the vortex action of the gas and create a change in its velocity within the funnel section 262. The vortex action is relieved at the lower end 264 of the funnel 262 as the upper section 234 is again effectively widened into th lower zone 235c as refrigerant gas is removed upwardly in the intermediate zone 235b through discharge conduit 241 to the refrigeration system. The funnel 262 acts to modify the centrifugal action of the refrigerant vapor so that the oil separator is self compensating for various load conditions and changes.

Referring now to FIG. 9 showing a simplified version of the FIG. 8 embodiment, the oil separator 316 has an oil separating and collecting member 339 with a cylindrical upper screen section 360 that receives the oil-refrigerant intake flow from the system compressor (12) in the upper zone 335a of the upper housing section whereby centrifugal swirling action in the upper chamber takes place and oil separation is initiated. The member 339 also has a tapering, conical lower screen section 362 extending downwardly in the intermediate zone 335b of the upper separation chamber of the main housing 331 which extends below the refrigerant vapor discharge intake 342 of outlet conduit 341. As in FIG. 8, the lower end 364 of the conical screen wall 362 is located in the intermediate zone 335b above and spaced by the lower zone 335c from the domed baffle 347. The lower conical wall section 362 may have a funnel-shaped support structure 366, such as a sheet metal frusto-conical funnel or, preferably, an open lattice work of metal strips or the like to provide a perforate, open support structure accommodating the passage of accumulated oil therethrough. In operation the increasing velocity of the vortex action in the conical screen section 362 is relieved at the lower end 364 due to the wider open area of the lower zone 335c below it.

The oil separator (16, 116, 216, 316) of the present invention may be further modified to accommodate size or space limitations of the other system components or the operational volume demands for oil. For instance in another embodiment illustrated in FIG. 10, the vertical oil separator 416 may be shortened substantially to reduce the volumetric size of the lower oil collecting section 444 and provide an oil float device 470 to deliver oil to a separate oil reservoir (not shown) connected to the oil outlet port 420. In this arrangement, the separator will hold about 1-2 pounds of oil, and the float mechanism 470 has a float ball that lifts to maintain a predetermined oil level. The lower section 444 is separated from the lower zone 435c of the upper section 434 by baffle 447 having an upper plate or top wall 452 spaced from sidewall 438 on housing member 449 to provide an oil passageway 451 therebetween. The descending oil flows through openings in the housing. First and second oil filters (440a, 440b and/or 440, 442) are provided in the upper section, as previously described.

From the foregoing it will be evident that the oil separator of the present invention provides a greatly improved and simplified oil separation and reservoir apparatus that meets the objects set forth. The scope of the invention encompasses such changes and modifications as will be readily apparent to those skilled in the art and within the scope of the appended claims.

Claims

1. A vertical oil separator for removing oil from a refrigerant gas and oil mixture on the high side of a refrigeration/chiller system comprising: a housing having upper and lower sections separated by a baffle, said upper section forming an oil separation chamber above the baffle and having a sidewall with an inlet constructed and arranged to receive the refrigerant gas and oil mixture from the system and produce a circulating flow path around the sidewall of the upper chamber, and a refrigerant gas outlet spaced from the sidewall within the upper chamber, said lower section forming an oil receiving chamber below the baffle and having an oil outlet therefrom, a first oil filter device associated with the sidewall in said upper chamber for removing oil from the circulating flow of the gas and oil mixture, and at least one other filter device for removing oil from the circulating flow path upstream of the refrigerant gas outlet from the upper chamber.

2. The oil separator of claim 1, wherein said upper section has upper, intermediate and lower zones, said inlet for the refrigerant gas and oil mixture from the system being disposed in the upper zone and said refrigerant gas outlet being disposed therebelow in the intermediate zone, and said first oil filter device comprising a primary mesh liner extending around the sidewall in the upper zone of the upper section to thereby perform the primary oil separation function of said oil separator.

3. The oil separator of claim 2, wherein said other filter device comprises a secondary mesh liner constructed and arranged in the circulating flow path downstream of the primary mesh liner to supplement the removal of oil before discharging refrigerant gas from the intermediate zone through the gas outlet.

4. The oil separator of claim 3, wherein the refrigerant gas outlet comprises an outlet conduit extending into the intermediate zone of the upper section and having an outlet opening through which refrigerant gas passes into the outlet conduit and downstream to the system, and said secondary mesh liner is constructed and arranged to cover the outlet opening for final oil removal during refrigerant gas discharge therethrough to the system.

5. The oil separator of claim 3, wherein said secondary mesh liner is constructed and arranged as a downwardly tapering funnel member extending from the primary mesh liner at the upper zone through the intermediate zone and below the gas outlet opening therein.

6. The oil separator of claim 5, wherein the secondary mesh liner is formed as a continuation of the primary mesh liner and functions to accelerate the flow rate of the gas and oil mixture in the downwardly circulating flow path impinging thereagainst for secondary oil separation before discharge of refrigerant gas through the gas outlet.

7. The oil separator of claim 5, in which said tapering funnel member has a large upper end connected to the primary mesh liner adjacent to the upper zone sidewall and has an inwardly narrowed lower end spaced from the sidewall at a lower end of the intermediate zone.

8. The oil separator of claim 7, including a structural support constructed and arranged for supporting the secondary mesh liner.

9. The oil separator of claim 8, in which said structural support comprises a funnel-shaped member connected at its top to the sidewall and underlying the secondary mesh liner.

10. The oil separator of claim 9, in which the funnel-shaped member comprises a framework supporting said secondary mesh liner and having openings therethrough to accommodate the passage of oil from the secondary mesh liner.

11. The oil separator of claim 3, in which said secondary mesh liner is constructed and arranged to extend around the sidewall in the upper zone between the primary mesh liner and the sidewall surface to thereby form a double mesh liner extending vertically from the level of the oil and gas mixture inlet downwardly through the upper zone.

12. The oil separator of claim 11, wherein at least one of said mesh liners extends downwardly through the lower zone of said upper section substantially to said baffle.

13. The oil separator of claim 2, wherein said baffle is constructed and arranged to extend across the oil separator between the upper and lower sections thereof, said baffle having an outer peripheral edge with at least one side portion thereof being spaced away from the sidewall to form an oil passageway to the lower section.

14. The oil separator of claim 13, wherein the baffle has an upper top wall accommodating oil flow outwardly around the peripheral edge and downwardly therefrom through the oil passageway to the lower section.

15. The oil separator of claim 14, including other oil passageways for accommodating oil flow in the lower section.

16. The oil separator of claim 15, in which the top wall of the baffle is upwardly domed and asymmetrically mounted in the oil separator with another side portion being attached to the sidewall to thereby locate the one side portion and the oil passageway opposite thereto.

17. The oil separator of claim 16, in which said other oil passageway comprises ports in the top wall adjacent to said another side portion attached to the sidewall.

18. A vertical oil separator for removing oil from a refrigerant gas and oil mixture on the high side of a refrigeration/chiller system comprising: a housing having an upper section forming an oil separation chamber with a cylindrical sidewall and an inlet constructed and arranged for receiving the refrigerant gas and oil mixture from the system compressor and creating a spiraling flow path around said sidewall in the upper chamber, an oil filter device in the oil separation chamber for removing oil particles from the spiraling flow path of the gas and oil mixture, and a gas outlet spaced from the sidewall within the upper chamber for delivering refrigerant gas to the system condenser, said housing having a lower section forming an oil receiving chamber below and separated from the upper chamber by a baffle, said lower chamber having an oil outlet therefrom, said oil filter device including a first filter associated with the sidewall in said upper chamber for removing oil out of the spiraling flow path of the gas and oil mixture, and other filters constructed and arranged for removing oil from the spiraling flow path upstream of the gas outlet from the upper chamber.

19. The oil separator of claim 18, wherein said upper chamber has upper, intermediate and lower zones, said inlet for the refrigerant gas and oil mixture from the system being disposed in the upper zone and said refrigerant gas outlet being disposed therebelow in the intermediate zone, and said first oil filter comprising a primary mesh liner extending around the sidewall in the upper zone of the upper chamber to thereby perform the primary oil separation function of said oil separator, said other filters comprising a secondary mesh liner constructed and arranged to extend around the sidewall in the upper zone between the primary mesh liner and the sidewall surface to thereby form a double mesh liner extending vertically from the level of the oil and gas mixture inlet downwardly through the upper.

20. The oil separator of claim 18, wherein said baffle is constructed and arranged to extend across the oil separator between the upper and lower chambers thereof, said baffle having an outer peripheral edge with at least one side portion thereof being spaced away from the sidewall to form an oil passageway to the lower chamber, the top wall of the baffle being upwardly domed and asymmetrically mounted in the oil separator with another side portion being attached to the sidewall to thereby locate the one side portion and the oil passageway opposite hereto.