Patent ID: 12241461

DETAILED DESCRIPTION

Referring now to the drawings and more particularly toFIG.1, one exemplary embodiment is illustrated of a system for reclaiming compressor lubricating oil (hereinafter “oil”) vented from the compressor crankcase due to blow-by. In general, the system of the present disclosure can be used with any type of gas compressor100that includes a crankcase102housing moving parts and oil104therein as is well-understood in the art. In general, the compressor's moving parts include at least one piston110disposed within a cylinder112. One or more piston rings114disposed about piston110define a seal with cylinder112. A piston rod116couples piston110to a crank arm118mounted in crankcase102.

A gas200, either at atmospheric pressure or some elevated pressure, enters cylinder112and is compressed by piston110and expelled from cylinder112as a compressed gas201. Some of gas200enters crankcase102as blow-by indicated by wavy lines202. Typically, blow-by gas202flows past the compressor's piston rings114and into crankcase102. Gas200can be a variety of inert gases to include breathable air, nitrogen, helium, etc.

Pressure build-up in crankcase102due to blow-by gas202is released via a pressure relief vent106in crankcase102. As is known in the art, only inert blow-by gases can be vented to a surrounding atmosphere. Further, blow-by gas can only be vented if adequate ventilation is in place around the compressor system to avoid the danger of asphyxiation of personnel. Prior to venting, some of oil104mixes with blow-by gas202to form a mist of gas and oil as indicated by wavy arrow204. Gas/oil mist204exits crankcase102via vent106. The amount of oil in gas/oil mist204increases with increasing flow of blow-by gas202.

The methods and systems described herein reclaim the oil portion of gas/oil mist204and return it to crankcase102. The oil reclamation methods and systems described herein may be used/integrated with existing gas compressors or may be included as an integral aspect of new gas compressors without departing from the scope of the present disclosure. Regardless of whether the compressor is an existing or new gas compressor, a coalescence filter10is disposed in the path of gas/oil mist204to separate the mist into its constituent parts of gas and oil. A variety of coalescing filters are commercially available.

In the embodiment illustrated inFIG.1, pressure relief vent106is placed in fluid communication with coalescence filter10such that all of gas/oil mist204is introduced into filter10. The separated gas204A can be, for example, vented into the surrounding environment when separated gas204A is inert. The separated oil204B and its flow path back to crankcase102are indicated by a bold line throughout the drawings. Separated oil204B is first provided to (e.g., via a conduit) a vessel or reservoir12that holds separated oil204B. In some embodiments, the portion of coalescence filter10where separated oil204B collects is located above at least a portion of reservoir12so that gravity can provide the motive force for movement of separated oil204B to reservoir12.

Mounted in reservoir12is a sensor14(e.g., a limit switch) that essentially continuously monitors the amount of separated oil204B contained in reservoir12. For example, if sensor14is a limit switch, it can be configured to have a low-level sensing element16positioned at a lower portion of reservoir12, and have a high-level sensing element18positioned at an upper portion of reservoir12. Low-level sensing element16is activated when the surface206of separated oil204B in reservoir12falls below sensing element16. High-level sensing element18is activated when the surface206of separated oil204B goes above sensing element18. In some embodiments, activation of either sensing element16or18causes them to generate a corresponding electrical signal16S or18S that is maintained until the other sensing element is activated.

Separated oil204B in reservoir12is provided to an inlet22of a pump20via, for example, a conduit (not shown). Low-level electrical signal16S is applied to pump20such that pump20is turned “OFF” or deactivated in the presence of signal16S. High-level electrical signal18S is applied to pump20such that pump20is turned “ON” or activated in the presence of signal18S. More generally, activation of high-level sensing element18results in pump20being energized, while activation of low-level sensing element16results in pump20being de-energized. When pump20is turned “ON”, separated oil204B in vessel12is pumped therefrom and through to pump outlet24. Pump20remains in its “ON” state until low-level electrical signal16S is received. When pump20is “ON”, separated oil204B is fed back (e.g., via a conduit) to crankcase102of compressor100. Disposed between pump outlet24and crankcase102is a check valve26that only permits flow of separated oil204B from pump20into crankcase102and assures that gas/oil mist204can only exit from crankcase102through coalescence filter10. That is, when pump20is “ON”, a pressure differential is created across check valve26causing it to open for establishment of a flow path there through.

In some embodiments, pump20is an electric pump that can be configured to be operable only when the compressor's corresponding compressor motor is operating. For example and as shown inFIG.2, sensor14controlling pump20can be wired in series with an auxiliary switch28whose opening and closing is controlled by the compressor's motor controller120that is coupled to the compressor's motor122via electrical circuitry (not shown). Briefly, auxiliary switch28is configured to close when motor controller120is energized to signal the run operation of compressor motor112. When this occurs, electric power is supplied through sensor14to pump20thereby enabling potential operation of pump20, i.e., enabling its operation when signal18S is also received. When motor controller120is de-energized to signal the stopping of compressor motor122, auxiliary switch28is configured to open thereby disabling the potential operation of pump20even if signal18S is received. Electric power routed to pump20through sensor14can be provided, for example, by control power shared from motor controller120when it is energized in ways that would be understood by one of ordinary skill in the art.

The methods and systems described herein may be used for oil reclamation in single-stage compressors or multi-stage compressors. As is known in the art, multi-stage compressors have one or more first stage(s) operating with a gas input at atmospheric pressure whose outputs are supplied to one or more booster compressors operating with a gas input at a pressure that is greater than atmospheric pressure.

Any of the embodiments described herein could integrate the above-described coalescence filter10with reservoir12. For example, another embodiment is illustrated inFIG.3where coalescence filter10is disposed in reservoir12such that separated oil204B is initially collected immediately below coalescence filter10under the force of gravity.

Some compressor systems are required to run for long and continuous periods of time spanning many hours to days or longer, while other compressor systems are designed and installed in applications that only require the compressor to be operated for periodic or intermittent periods of time spanning minutes to a few hours. In cases where the compressor will only be operated intermittently, blow-by gas oil reclamation may be accomplished without the use of a pump. For example,FIG.4illustrates an oil reclamation system in which separated oil204B is collected in small reservoir32that can be immediately and gravitationally beneath coalescence filter10. Reservoir32can be coupled to or integrated with coalescence filter10. In either case, reservoir32is located at a position that is gravitationally above the compressor's crankcase102. A gravitational flow path34is defined between a lowest gravitational position32A of reservoir32and crankcase102. That is, gravitational forces control fluid movement all along flow path34. Flow path34includes conduits (not shown) carrying separated oil204B from position32A to an inlet36A of a check valve36, and from an outlet36B of check valve36to crankcase102. Check valve36is configured to be closed (i.e., seated) when the pressure in crankcase102(“PC”) is greater than the pressure head caused by separated oil204B at inlet36A of check valve36(“PO”), and open (i.e., unseated) when the pressure PCis less than the head pressure PO. When compressor100is operational, the pressure PCwill be greater than the head pressure PO. However, when compressor is non-operational, the pressure PCquickly drops to ambient pressure due to venting through vent106. Once the pressure PCdrops below the head pressure PO, check valve36opens to establish a flow path there through such that separated oil204B is free to flow under the force of gravity back into crankcase102.

The advantages of the methods and systems described herein are numerous. A gas compressor's crankcase oil that has been traditionally vented and lost in a blow-by-generated gas/oil mist is reclaimed and restored into the crankcase. The system is fully automated for both intermittently-operated and continually-operated compressors thereby requiring no user intervention between scheduled maintenance periods. In tests of embodiments described herein, the time intervals between compressor-crankcase oil maintenance and/or re-fill operations has been substantially increased thereby reducing maintenance concerns and costs, while also eliminating lost-oil clean-up work and environmental concerns.

Although the methods and systems have been described relative to specific embodiments thereof, there are numerous variations and modifications that will be readily apparent to those skilled in the art in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the methods and systems may be practiced other than as specifically described.