HELIUM COMPRESSOR SYSTEM WITH UNMODIFIED SCROLL COMPRESSOR

Abstract

The disclosed invention provides an unmodified scroll compressor with enhanced oil management system that enables the compressor system to compress helium. The compressor system includes a standard scroll compressor, oil separator, and an adsorber. The compressor includes a housing containing an orbiting scroll and a stationary scroll, a motor, and an oil sump in a bottom of the housing. The stationary scroll has one or more injection ports, and the housing contains a single discharge port, a return port, and a single injection port connected to the injection ports of the stationary scroll. The oil separator receives a mixture of helium and oil from the discharge port. The compressor system further includes a line bringing a first fraction of oil from the oil separator to the injection port, one or more lines bringing a second fraction of oil to the return port along with helium. The adsorber retains a third fraction of oil.

Claims

1. A helium compressor system using an unmodified scroll compressor designed for air conditioning or food storage service, comprising: a compressor having a housing, comprising: a scroll including an orbiting scroll and a stationary scroll, wherein the stationary scroll has one or more injection ports; a discharge port in the housing, through which a mixture of helium at high pressure and oil is discharged; at least one return port in the housing, which receives helium at low pressure; an injection port in the housing, which is connected to the one or more injection ports of the stationary scroll; a motor that has a drive shaft that drives the orbiting scroll; and a compressor oil sump located in a bottom of the housing; and an oil management system comprising: an oil separator receiving the mixture of the helium at high pressure and the oil from the discharge port; a first line bringing a first fraction of the oil from the oil separator to the one or more injection ports of the stationary scroll through the injection port of the housing; one or more return lines bringing a second fraction of the oil to the at least one return port along with the helium at low pressure; and an adsorber that retains a third fraction of the oil.

2. The helium compressor system of claim 1 wherein the scroll includes an inlet that receives the helium at low pressure supplied through the at least one return port, and an outlet that discharges the helium at high pressure.

3. The helium compressor system of claim 2 wherein the housing includes a high pressure section formed above the scroll, and the helium at high pressure is discharged to the high pressure section from the outlet of the scroll.

4. The helium compressor system of claim 2 wherein the one or more injection ports of the scroll are located between the inlet and outlet of the scroll.

5. The helium compressor system of claim 1 wherein the housing includes a low pressure section below the scroll, and the one or more returns ports are connected to the low pressure section.

6. The helium compressor system of claim 1 wherein the oil separator comprises a float valve through which a portion of the second fraction of the oil flows to the one or more return lines.

7. The helium compressor system of claim 6 wherein the oil management system further comprises a demister connected between the oil separator and the adsorber, wherein another portion of the second fraction of the oil flows to the one or more return lines from the demister.

8. The helium compressor system of claim 1 wherein the oil separator is configured to maintain a constant oil level in the oil separator, and an oil level in the compressor oil sump drops as the third fraction of the oil is retained in the adsorber.

9. The helium compressor system of claim 1 wherein the oil management system further comprises an oil cooler that cools the first fraction of the oil.

10. The helium compressor system of claim 1 wherein the discharge port is located in a bottom portion of the housing below the scroll.

11. The helium compressor system of claim 1 wherein the discharge port is configured to maintain a constant oil level in the compressor oil sump, and an oil level in the oil separator drops as the third fraction of the oil is retained in the adsorber.

12. The helium compressor system of claim 1 wherein the scroll includes an inlet that is connected to the at least one return port and receives the helium at low pressure and the second fraction of the oil supplied through the at least one return port, and an outlet that discharges the helium at high pressure.

13. The helium compressor system of claim 1 further comprising a demister connected between the oil separator and the adsorber, wherein the second fraction of the oil flows to the one or more return lines from the demister.

14. An oil lubricated scroll compressor system that supplies compressed helium to one or more cryogenic expanders, comprising: a compressor, comprising: a scroll that compresses helium, wherein the scroll comprises an inlet to receive helium at low pressure, an outlet to discharge helium at high pressure, and one or more injection ports; an oil sump that is located in a bottom of the compressor and contains oil to lubricate the compressor; a discharge port through which a mixture of the helium at high pressure and the oil is discharged; at least one return port that receives the helium at low pressure; an injection port connected to the one or more injection ports of the scroll; and a motor that has a drive shaft that drives the scroll; and an oil management system comprising: an oil separator that receives the mixture of the helium at high pressure and the oil from the discharge port; a first line bringing a first fraction of the oil from the oil separator to the one or more injection ports of the scroll; one or more return lines bringing a second fraction of the oil from the oil separator to the at least one return port along with the helium at low pressure; and an adsorber that retains a third fraction of the oil.

15. The oil lubricated scroll compressor system of claim 14 wherein the second fraction of the oil includes oil supplied through a float valve of the oil separator and oil supplied through a demister that is connected between the oil separator and the adsorber.

16. The oil lubricated scroll compressor system of claim 14 wherein the at least one return port is located between the scroll and the oil sump of the compressor.

17. The oil lubricated scroll compressor system of claim 14 wherein the oil separator is configured to maintain a constant oil level in the oil separator, and an oil level in the oil sump of the compressor drops as the third fraction of the oil is retained in the adsorber.

18. The oil lubricated scroll compressor system of claim 14 wherein the discharge port is located between the scroll and the oil sump of the compressor.

19. The oil lubricated scroll compressor system of claim 14 wherein the discharge port is configured to maintain a constant oil level in the compressor oil sump, and an oil level in the oil separator drops as the third fraction of the oil is retained in the adsorber.

20. The oil lubricated scroll compressor system of claim 14 further comprising an oil cooler that cools the first fraction of the oil.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The drawing figures depict one or more implementations in accord with the present concepts, by way of example only, not by way of limitations. In the figures, like reference numerals refer to the same or similar elements.

[0015] FIG. 1 is a schematic diagram of an embodiment of the scroll compressor system in which helium returning at low pressure flows into a low pressure section of the housing that contains the motor and oil sump.

[0016] FIG. 2 is a schematic diagram of another embodiment of the scroll compressor system in which the helium returning at low pressure flows directly into the scroll placed inside the housing, and then is discharged into the high pressure section of the housing that contains the motor and oil sump.

DETAILED DESCRIPTIONS

[0017] In this section, some embodiments of the invention will be described more fully with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention, however, may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout, and prime notation is used to indicate similar elements in alternative embodiments. Parts that are the same or similar in the drawings have the same numbers and descriptions are usually not repeated.

[0018] With reference to FIG. 1, shown is a schematic diagram of an embodiment of oil-lubricated helium compressor system 100 in which helium returning at low pressure flows into a low pressure section of the housing 2 that contains the motor and oil sump. The compressor system 100 includes a compressor 110 and an oil management system 120 coupled to the compressor 110. The oil management system 120 includes bulk oil separator 5, demister 7, adsorber 8, and lines 12, 17, 22, 23, 25, 26, and 29. The compressor 110 includes a compressor housing 2 which contains scroll 13, motor 15, drive shaft 14, oil sump 18, oil pump 16. A low pressure section 3 is formed below the scroll 13, and a high pressure section 4 is formed above the scroll 13. Helium at low pressure returns through one or more return lines 17 and is supplied into the housing 2 through at least one return port 31. The helium at low pressure may be mixed with oil returning from bulk oil separator 5 and demister 7. As the helium enters into low pressure section 3 of the compressor 110, most of the oil falls to oil sump 18 at the bottom of the housing 2, and the helium along with some oil mist flows into scroll 13 through an inlet 32 of the scroll 13. The scroll 13 includes an inlet 32 that receives the helium at low pressure supplied through the return port 31, and an outlet 28 that discharges compressed helium at high pressure to the high pressure section 4 above the scroll 13. The return port 31 may be connected to the low pressure section 3. The return port 31 may be located between the scroll 13 and the oil sump 18. Oil that lubricates the bearings in the compressor 110 is pumped up through drive shaft 14. Some of the lubricating oil and the oil that is injected into the scroll 13 is compressed along with the helium in the scroll 13. A mixture of the helium at high pressure and oil is discharged through an outlet 28 of the scroll 13 into high pressure section 4 of the compressor 110. From the high pressure section 4, the mixture of helium at high pressure and oil flows through discharge port 30 and the line 12 into bulk oil separator 5.

[0019] The scroll 13 includes a stationary scroll 13A and orbiting scroll 13B. The stationary scroll 13A may be located in the upper part of the compressor housing 2. The orbiting scroll 13B may be connected to the end of a motor driven shaft 14 with a mechanism that causes the orbiting scroll 13B to orbit in the stationary scroll 13A. Gas entering the outer volutes is compressed as it spirals toward the center where it is discharged. Oil collects in the oil sump 18 and is pumped through the drive shaft 14 to lubricate the bearings or other mechanical parts in the compressor 110. The stationary scroll 13A has one or more injection ports 11A that are connected to the injection port 11 of the housing 2. The one or more injection ports 11A of the scroll 13 may be located between the inlet 32 and outlet 28 of the scroll 13.

[0020] The oil in the mixture of helium and oil may be separated in the bulk oil separator 5, and the oil may flow to the sump 19 formed in the bottom of the bulk oil separator 5. A fraction of oil in the sump 19 of bulk oil separator 5 returns to oil injection port 11 through oil cooler 9 and line 29. This oil is referred to as cooling oil since about 70% of the heat of compression is taken out in oil cooler 9. The cooling oil circulation rate is controlled by orifice 10 formed on the line 29. The cooling oil is supplied to the scroll 13 through one or more injection ports 11A of the stationary scroll 13A which is connected to the injection port 11 of the housing 2. The cooling oil supplied from the injection ports 11A and lubricating oil supplied through the shaft 14 may be mixed in the scroll 13, and may be discharged to the high pressure section 4 through the outlet 28 together with compressed helium at high pressure.

[0021] Meanwhile, another fraction of the oil separated in the bulk oil separator 5 may flow to line 22 through a float valve 21 that may be formed in the bulk oil separator 5. The line 22 is connected to the one or more return lines 17 though which helium at low pressure from an cryogenic expander (not shown) returns to the housing 2. This fraction of the oil may be mixed with the returning helium in the one or more lines 17, and returns to oil sump 18 through the return port 31. The float valve 21 enables the bulk oil separator 5 to maintain a constant level of oil in bulk oil separator 5.

[0022] Helium and some entrained oil flow from bulk oil separator 5 through helium cooler 6 and line 23 into demister 7. Oil separated from the mixture of helium and oil collects in sump 20 in the demister 7, and is then returned to compressor sump 18 through orifice 24, line 25, and return lines 17. A very small amount of oil flows with the helium from demister 7 through line 26 into adsorber 8 where the oil is retained. Oil free helium at high pressure then flows from adsorber 8 through line 27 to a cryogenic expander (not shown). As oil collects in adsorber 8 over a period of years, the oil level in compressor sump 18 drops.

[0023] A first fraction of oil in the oil separator 5 returns to the injection ports 11A of the stationary scroll 13A through the line 29 from the bottom of the oil separator 5. A second fraction of oil may include oil in the oil separator 5 that returns to the return port 31 through the lines 17 and 22, and oil in the demister 7 that returns to the return port 31 through lines 17 and 25. A third fraction of oil may be retained in the adsorber 8. In the embodiment shown in FIG. 1, the oil level in the oil separator 5 is maintained at a constant level, and the oil level in the compressor sump 18 is depleted as the third fraction of oil is retained in the adsorber 8. The floating valve 21 may enable the oil separator 5 to maintain a constant oil level.

[0024] With reference to FIG. 2, shown is a schematic diagram of another embodiment of oil-lubricated helium compressor system 200. The compressor system 200 includes a compressor 210 and an oil management system 220 coupled to the compressor 210. The oil management system 220 incudes bulk oil separator 5, demister 7, adsorber 8, and lines 12, 17, 23, 25, 26 and 29. The compressor 210 includes a compressor housing 2 which contains scroll 13, motor 15, drive shaft 14, oil sump 18, and oil pump 16. A high pressure section 4 is formed inside the housing 2. Helium at low pressure returns from a cryogenic expander (not shown) through line 17 and at least one return port 31. The helium at low pressure may be mixed in the return line 17 with oil returning from demister 7. The scroll 13 has an inlet 32 that is connected to the return port 31 and receives the helium at low pressure and returning oil. The helium at low pressure is compressed in the scroll 13. Helium along with the oil from demister 7 flows directly into scroll 13 through the inlet 32. Oil that lubricates the bearings in the compressor 210 is pumped up through shaft 14. Some of the lubricating oil, oil from demister 7, and oil that is injected into the scroll 13 through injection ports 11 and 11A are compressed along with the helium, and are discharged through outlet 28 of the scroll 13 into high pressure section 4 of the compressor 210. In the high pressure section 4, most of the oil separates from the helium and collects in compressor sump 18.

[0025] FIG. 2 shows discharge port 30 below the motor 15. The discharge port 30 is located in a bottom portion of the housing 2 below the scroll 13. The discharge port 30 may be located between the scroll 13 and the oil sump 18. The oil level in sump 18 may be maintained at substantially the same level as the discharge port 30 such that oil may flow out with the helium through line 12 to bulk oil separator 5. From this point, the oil management processes are the same as those of the embodiment shown in FIG. 1 except that the oil that collects in adsorber 8 comes from oil sump 19 in bulk oil separator 5 rather than oil sump 18 in the compressor 210.

[0026] The oil in the mixture of helium and oil may be separated in the bulk oil separator 5, and the oil may flow to the sump 19 formed in the bottom of the bulk oil separator 5. A fraction of oil in the sump 19 of bulk oil separator 5 returns to oil injection port 11 through oil cooler 9 and line 29. This oil is referred to as cooling oil since about 70% of the heat of compression is taken out in oil cooler 9. The cooling oil circulation rate is controlled by orifice 10 formed on the line 29. The cooling oil is supplied to the scroll 13 through one or more injection ports 11A of the stationary scroll 13A. The cooling oil supplied from the injection ports 11A, the lubricating oil supplied through the shaft 14, and the oil returning from the demister 7 through the return lines 17 may be mixed in the scroll 13, and may be discharged to the high pressure section 4 through the outlet 28 together with compressed helium at high pressure.

[0027] Another fraction of the oil separated in the bulk oil separator 5 may flow to line 23 to demister 7 through helium cooler 6. Separated oil in the demister 7 collects in sump 20, and is then returned to compressor sump 18 through orifice 24, line 29, and return line 17. A very small amount of oil flows with the helium from demister 7 through line 26 into adsorber 8 where the oil is retained. Oil free helium at high pressure then flows from adsorber 8 through line 27 to a cryogenic expander (not shown). As oil collects in adsorber 8 over a period of years, the oil level in the bulk oil separator 5 drops while the oil level in the sump 18 of the compressor 210 is maintained at a constant level.

[0028] A first fraction of oil in the oil separator 5 returns to the one or more injection ports 11A of the stationary scroll 13A through the line 29 from the bottom of the oil separator 5. A second fraction of oil in the oil separator 5 returns to the return port 31 along with helium through the demister 7 and lines 17, 23 and 25. A third fraction of oil may be retained in the adsorber 8. In the embodiment shown in FIG. 2, the oil level in the oil sump 18 of the housing 2 is constant as oil flows out with helium through line 12 to bulk oil separator 5, and the oil level in the oil separator 5 external to the compressor 210 is depleted as the third fraction of oil is retained in the adsorber 8.

[0029] It is noted that all of the standard compressors described in the background section that have the motor in the high pressure section of the housing show the gas discharge port above the motor. Application of these compressors with standard refrigerants have a fixed amount of oil in the system that serves as a lubricant and not as a coolant. Most of the oil circulates within the compressor and collects in the sump at a level below the discharge port. FIG. 2 shows discharge port 30 below the level where oil would put a drag on the motor and above the level for oil in an application with standard refrigerants.

[0030] The terms and descriptions used herein are set forth by way of illustration only and are not meant as limitations. Those skilled in the art will recognize that many variations are possible within the spirit and scope of the invention and the embodiments described herein.