Compressor with liquid injection cooling

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PCT/US2011/049599 high levels of vibration and noise. This technology has he en used for many industrial applications such as natural gas compression.

[003J Rotary compressors use a rotating component to perform compression. As noted in the art, rotary compressors typically have the following features in common; ¢1) they impart energy to the gas being compressed by way of an input shaft moving a single or multiple rotating elements; (2) they perform the compression in an intermittent mode; and (3) they do not nse inlet or discharge valves. (Broun, Compressors: Selection and Sizing, 3rd Ed., at 6). As further noted in Brown, rotary compressor designs are generally suitable for designs in which less titan 20:1 pressure ratios and 1000 CFM flow rates are desired. For pressure ratios above 20:1, Royce suggests that multistage reciprocating compressors should be used instead.

[004[ Typical rotary compressor designs include die rolling piston, screw compressor, scroll compressor, lobe, liquid ring, and rotary vane compressors.

Each of diese traditional compressors has deficiencies for producing high pressure, near isothermal conditions.

[005) The design of a rotating element/rotor/lobe against a radially moving element/piston to progressively reduce die volume of a fluid has been utilized as early as die mid-19di century with die introduction of die “Yule Rotary Steam Engine.” Developments have been made to small-sized compressors utilizing dûs methodology into refrigeration compression applications. However, current Yuletype designs are limited due to problems with mechanical spring durability' (returning the piston element) as well as chatter (insufficient acceleration of the piston in order to maintain contact with the rotor).

[006j For commercial applications, such as compressors for refrigerators, small rolling piston or rotary⁷ vane designs are typically used. (P N Ananthanarayanan, Basic Refrigeration and Air Conditioning, 3rd Ed., at 171-72.)

In dicsc designs, a closed oil-lubricating system is typically used.

[007J Rolling piston designs typically allow for a significant amount of leakage between an eccentrically mounted circular rotor, die interior wall of die casing, and/or the vane diat contacts die rotor, By^r spinning the rolling piston faster,

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PCT/US2011/949599 tlie leakages are deemed acceptable because die desired pressure and flow rate for tl ie application can be easily reached even with these lasses. The benefit of a small selfcontained compressor is more important than seeking higher pressure ratios.

[008) Rotary vane designs typically use a single circular rotor mounted eccentrically in a cylinder slightly larger dian die rotor. Multiple vanes are positioned in slots in die rotor and are kept in contact with die cylinder as the rotor turns typically by spring or centrifugal force inside die rotor. The design and operation of these type of compressors may be found in Mark’s Standard Handbook for Mechanical Engineers, Eleventh Edition, at 14:33-34.

[0091 hi a sliding-vane compressor design, vanes are mounted inside die rotor to slide against the casitig waif Alternatively, rolling piston designs utilize a vane mounted within die cylinder dial slides against the rotor. These designs are limited by the amount of restoring force that can be provided and thus the pressure diat can be yielded.

[010J Each of these types of prior art compressors has limits oil die maximum pressure differential that it can proride. Typical factors include mechanical stresses and temperature rise. One proposed solution is to use multistaging'. In multistaging, multiple compression stages are applied sequentially. Intercooliiig. or cooling between stages, is used to cool tlie working fluid down to an acceptable level to be input into die next stage of compression. Tilts is typically done by passing (he working fluid du ougli a heat exchanger in diermal communication widi a cooler fluid. However, intercooling can result in some condensation of liquid and typically requires filtering out of the liquid elements. Mnllistaging greatly' increases the complexity ol the overall compression system and adds costs due to die increased number of components required. Additionally, die increased number of components leads to decreased reliability and die overall size and weight of the system arc markedly increased.

[011) For industrial applications, single- and double-acting reciprocating compressoi's and helical-screw type rotary compressors ate most commonly used. Single-acdug reciprocating compressors are similar to an automotive type piston widi compression occurring on die top side of the piston during each revolution of tlie

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PCT/US2011/949599 cranksliaft. These machines can operate \vitli a single-stage discharging between 25 and 125 psig or in two stages, with outputs ranging from 125 to 175 psig or higher. Single-acting reciprocating compressors are rarely seen in sizes above 25 HP. These types of compressors are typically afferted by vibration and mechanical stress and require frequent maintenance. They also suffer from low efficiency due to insufficient cooling.

[012] Double-acting reciprocating compressors use both sides of die piston for compression, effectively doubling the machine’s capacity’ for a given cylinder size. They can operate as a single-stage or with multiple stages and are typically sized greater dian 10 HP with discharge pressures above 50 psig. Machines of this type widi only one or two cylinders require large foundations due to the unbalanced reciprocating forces. Double-acting reciprocating compressors tend to be quite robust and reliable, but are not sufficiently efficient, require frequent valve maintenance, and have extremely high capital costs.

[013] Lubricant-flooded rotary screw compressors operate by forcing fluid between two intenneshing rotors within a housing which has an inlet port at otie end and a discharge port at tire other. Lubricant is injected into the chamber to lubricate the rotors and bearings, take away the heat of compression, and help to seal the clearances between the two rotors and between die rotors and housing. This style of compressor is reliable widi few moving parts. However, it becomes quite inefficient al higher discharge pressures (above approximately 200 psig] due lo (he intermeshing rotor geometry being forced apart and leakage occurring. In addition, lack of valves and a built-in pressure ratio leads to frequent over or under compression, which translates into significant energy efficiency losses.

[014[ Rotary screw compressors aie also available uidrout lubricant in the compression chamber, aldiough diese types of machines are quite inefficient due to the lack of lubricant helping to sea! between die rotors. They arc a requirement in some process industries such as food and beverage, semiconductor, and pharmaceuticals, which cannot tolerate any oil in die compressed air used in dieir processes. Efficiency* of dry rotary screw compressors are 15-20% below comparable

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PCT/US2011/049599 injected lubricated rotaiy screw compressors and aie typically used for discharge pressures below 150 psig.

[01-5] Using cooling in a compressor is understood to improve upon the efficiency of the compression process by extracting heat, allowing most of the energy to be transmitted to die gas and compressing with minimal temperature increase. Liquid injection has previously been utilized in other compression applications for cooling purposes. Further, it lias been suggested dial smaller droplet sizes of die injected liquid may provide additional benefits.

[016] In U.S. Pat. No. 4,497,185, lubricating oil was intercooied and injected through an atomizing nozzle into die inlet of a rotary screw compressor. In a similar fashion, U.S. Pat. No. 3,795,117 uses refrigerant, though not in an atomized fashion, diat is injected early in die compression stages of a rotary screw compressor. Rotary vane compressors have also attempted finely atomized liquid injection, as seen in U.S. Pat. No. 3,820,923.

[017J In each example, cooling of die fluid being compressed was desired. Liquid injection in rotary screw compressors is typically done at the inlet and not widiin die compression chamber. This provides some cooling benefits, but the liquid is given die entire compression cycle to coalesce and reduce its effectiv e heat transfer coefficient. Additionally, diese examples use liquids diat have lubrication and sealing as a primary beiiefiL. This affects die choice of liquid used and may adversely affect its heal transfer and absorption characteristics. Further, these styles of compressors have limited pressure capabilities and thus are limited in their potential market applications,

10181 Rotary designs for engines are also known, but suffer from deficiencies diat would make them unsuitable for an efficient compressor design. The most well-known example of a rotaiy engine is die Wank el engine. While tins engine has been shown to have benefits over conventional engines and has been commercialized with some success, it still suffers from multiple problems, including low reliability' and high levels of hydrocarbon emissions.

|0191 Published International Pat. App. No. WO 2010/017199 and U.S. Pat. Pub. No. 2011/0023814 relate to a rotaiy engine design using a rotor, multiple

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PCT/US2011/949599 gates to create the cliambers necessary for a combustion cycle, and an external can idrive for the gates. Tlie foire from the combustion cycle drives the rotor, which imparts force to an external element. Engines are designed for a temperature increase in the chamber and high temperatures associated with the combustion that occurs within an engine. Increased sealing requirements necessary for an effective compressor design are unnecessaiy and difficult to achieve. Combustion forces die use of positively contacting seals to achieve near perfect sealing, while leaving wide tolerances for metal expansion, taken up by the seals, in an engine. Further, injection of liquids for cooling would be counterproductive and coalescence is not addressed.

[0201 Liquid mist injection has been used in compressors, but with limited effectiveness. In U.S. Pat. No. 5,024,588, a liquid injection mist is described, but improved heat transfer is not addressed. In U.S. Pat, Publication. No. Ü.S. 2011/0023977, liquid is pumped dirough atomizing nozzles into a reciprocating piston compressor’s compression chamber prior to die start of compression. It is specified that liquid will only be injected through atomizing nozzles in low pressure applications. Liquid present in a reciprocating piston compressor’s cylinder causes a high risk for catastrophic failure due to hvdrolock, a consequence of the incompressibility of liquids when they build up in clearance volumes in a reciprocating piston, or oilier positive displacement, compressor. To prevent hydrolock situations, reciprocating piston compressors using liquid injection will typically have to operate at very slow speeds, adversely affecting die performance of tbe compressor.

[021 [ The prior art lacks compressor designs in which the application of liquid injection for cooling provides desired results lor a near-isothermal application. This is m large part due to die lack of a suitable positive displacement compressor design that can both accommodate a significant amount of liquid in the compression chamber and pass that liquid through die compressor outlet without damage.

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Brief Summary

[0221 The presently preferred embodiments are directed to rotary compressor designs. These designs are particularly suited for high pressure applications, typically above 200 psig with compression ratios typically above for existing high-pressure positive displacement compressors.

[023) One illustrative embodiment of the design includes a non-circularshaped rotor rotating widlin a cylindrical casing and mounted concentrically on a drive shaft inserted axially dirough die cylinder. The rotor is symmetrica! along the axis traveling from die drive shaft to the casing with cycloid and constant radius portions. The constant radius portion corresponds to die curvature of die cylindrical casing, dius providing a sealing portion. The changing rate of curvature on die odier portions provides for a noil-sealing portion, in dûs illustrative embodiment, the rotor is balanced by way of holes and counterweights.

[024) A gate structured similar to a reciprocating rectangular piston is inserted into and withdrawn from the bottom of the cylinder in a timed manner such diat die tip ot the piston remains in contact with or sufficiendv proximate to the surface of the rotor as it turns. The coordinated movement of die gate and the rotor separates the compression chamber into a low pressure and high pressure region.

[025) As die rotor rotates inside the cylinder, the compression volume is progressively reduced and compression of die fluid occurs. At the same time, die intake side is filled widi gas through die inlet. An inlet and exhaust are located to allow fluid to enter and exit die chamber at appropriate times. During the compression process, atomized liquid is injected into die compression chamber in such a way that a high and rapid rate of heat transfer is acliieved between die gas being compressed and die injected cooling liquid. This results in near isodiermal compression, which enables a much higher efficiency compression process.

[026) The rotaiy compressor embodiments sufficient to achieve near isodiermal compression are capable of achieving high pressure compression at higher efficiencies. It is capable of compressing gas only, a mixture of gas and

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PCT/US2011/049599 liquids, or for pumping liquids. As one of ordinal y skill in tire art would appreciate, the design can also be used as an expander.

[027( Tire particular rotor and gate designs may also be modified depending on application parameters. For example, different cycloidal and constant radii may be employed. Alternatively, double harmonic or other functions may be used for tire variable radius. The gate may be of one or multiple pieces. It may imp le nre nt a contacting dp-seal, liquid channel, or provide a non-contacting seal by which tire gate is proximate to tire rotor as it turns.

[028) Several embodiments provide mechanisms for driving the gate external to tire main casing. In one embodiment, a spring-backed cam drive system is used. In other;, a belt-based system with or without springs may be used. Iti yet another, a dual cam follower gate positioning system is used. Further, an offset gate guide system mav be used. Further still, linear actuator, magnetic drive, and scotch yoke systems may be used.

[029 J The presently' preferred embodiments provide advantages not found in the prior art- Tire design is tolerant of liquid in die system, both coming through tire inlet and injected for cooling purposes. High compression ratios are achievable due to effective cooling techniques. Lower vibration levels and noise are generated. Valves are used to minimize inefficiencies resulting from over- and undercoinpression common nr existing rotary compressors. Seals are used to allow higher pressures and slower speeds than typical with other rotary compressors. The rotor design allows for balanced, concentric motion, reduced acceleration of the gate, and effective sealing between high pressure and low pressure regions of the compression chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

[030) The invention can be better understood with reference to the following drawings and description. The components in the figures are not neressarily to scale, emphasis instead Ireing placed upon illustrating the principles of tlie invention. Moreover, in die figures, like referenced numerals designate coiTespondmg parts throughout die different views.

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[031 [ Figure 1 is a perspective view of a îotaiy compressor Midi a springbacked cam drive, in accordance with an embodiment of the present invention.

[032J Figure 2 is a right-side view of a rotary compressor with a springbacked cam drive in accordance with an embodiment of die present invention.

[033| Figure 3 is a left-side view of a rotaiy compressor with a springbacked cam drive in accordance with an embodiment of die present invention.

[034] Figure 4 is a front view of a rotaiy compressor with a spring-backed cam drive in accordance with an embodiment of die present invention.

[0351 Figure 5 is a back view of a rotaiy compressor with a spring-backed cam drive in accordance with an embodiment of die present invention.

[0361 Figure 6 is a top view of a rotary compressor with a spring-backed cam drive in accordance with an embodiment of die present invention.

[037 J Figure 7 is a bottom view· of a rotaiy compressor with a spring-backed cam drive in accordance with an embodiment of die present invention.

[038] Figure 8 is a cross-sectional view of a rotary' compressor with a springbacked cam drive in accordance with an embodiment of die present invention.

[039) Figure 9 is a perspective view of rotary compressor with a belt-driven, spring-biased gate positioning system in accordance with an embodiment of die present invention.

[040) Figure 10 is a perspective view of a rotaiy compressor widi a dual cam follower gate positioning system in accordance with an embodiment ofthe present invention.

[041 ) Figure 11 is a right-side view of a rotary compressor with a dual ram follower gate positioning system in accordance with an embodiment of die present invention.

[042) Figure 12 is a left-side view of a rotary compressor widi a dual cam follower gate positioning system in accordance with an embodiment of die present invention.

[043[ Figure 13 is a front view of a rotaiy' compressor with a dual cam follower gate positioning system in accordance widi an embodiment of the present invention.

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[044) Figure 14 is a back view of a îotaiy compressor with a dual cam follower gate positioning system in accordance with an embodiment of the present invention.

[04.5) Figure 15 is a top view of a rotaiy compressor with a dual cam follower gate positioning system in accordance with an embodiment of the present invention.

[046) Figure 16 is a bottom view of a rotaiy compressor with a dual cam follower gate positioning system in accordance with an embodiment of the present invention.

[047) Figure 17 is a ci oss-secdonal view of a rotary compressor with a dual cam follower gate positioning system in accordance with an embodiment of the present invention.

[048) Figure 18 is perspective view of a rotary compressor with a belt-driven gate positioning system in accordance vritlr an embodiment of die present invention.

[0491 Figure 19 is perspective view of a rotary compressor with an offset gate guide positioning system in accordance with an embodiment of the present invention.

[050) Figure 20 is a right-side view of a rotary compressor with an offset gate guide positioning system in accordance with an embodiment of die present invention.

[051) Figure 21 is a front view of a rotaiy compressor with an of) set gate guide positioning system in accordance with an embodiment of the present invention.

(052) Figure 22 is a cross-sectional view of a rotary compressor with an offset gate guide positioning system in accordance widi an embodiment of die present invention.

[0531 Figure 23 is perspective view of a rotary compressor with a linear actuator gate positioning system in accordance wadi an embodiment of die present invention.

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[054J Figures 24A and B are tight side and cross-section views, respectively, of a rotary compressor with a magnetic drive gate positioning system in accordance with an embodiment of the present invention

[055) Figure 25 is perspective view of a rotary compressor with a scotch yoke gate positioning system m accordance with an embodiment of tlie present invention.

[056J Figures 26A-F are cross-sectional views of die inside of an embodiment of a rotary compressor with a contacting tip seal in a compression cycle in accordance with an embodiment of the present invention,

[057( Figures 2 7 A-F are cross-sectional views of die inside of an embodiment of a rotary compressor without a contacting tip seal in a compression cycle in accordance widi ano die r embodiment of die present invention.

[058] Figure 28 is perspective, cross-sectional view of a rotary compressor in accordance widi an embodiment of die present invention.

[059J Figure 29 is a left-side view of an additional liquid injectors embodiment of die present invention.

[060) Figure 30 is a cross-section view of a rotor design in accordance widi an embodiment of the present invention.

[06 If Figures 31A-D are cross-sectional views of rotor designs in accordance with various embodiments of die present invention.

[062) Figures 32A and B aie perspectiv e and right-side views of a drive shaft, rotor, and gate in accordance with an embodiment of the present invention.

[063) Figure 33 is a perspective view of a gate with exhaust ports in accordance with an embodiment of the present invention.

[064J Figure 34A and B are a perspective view⁷ and magnified view of a gate widi notches, respectively, in accordance widi an embodiment of die present invention.

[065] Figure 35 is a cross-section ai, perspective view a gate vvidi a rolling tip in accordance widi an embodiment of die present invention.

[066) Figure 36 is a cross-sectional front view of a gate vvidi a liquid injection channel in accordance widi an embodiment of die present invention.

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Detailed Description of the Preferred Embodiments

[0671 To the extent that die following terms are utilized herein, die following definitions are applicable:

[0681 Balanced rotation: die center of mass of the rotating mass is located on die axis of rotation.

[0691 Chamber volume: any volume diat can contain fluids for compression.

[070) Compressor: a device used to increase the pressure ofa compressible fluid. The fluid can be eidier gas or vapor, and can have a wide molecular weight range.

[071J Concentric: die center or axis of one object coincides with die center or axis of a second object

[0721 Concentric rotation: rotation in which one object’s center of rotation is located on the same axis as die second object’s center of rotation.

[073] Positive displacement compressor: a compressor tliat collects a fixed volume of gas within a chamber and compresses it by reducing the chamber volume.

[074) Proximate: sufficiently close to restrict fluid flow between high pressure and low pressure regions. Restiichon does not need to be absolute: some leakage is acceptable.

[075) Rotor. A rotating element driven by a mechanical force to rotate about an axis. As used in a compressor design, die rotor imparts energy to a fluid.

[076J Rotarycompressor: Λ po sitive-d is place nient co m pressa r tha t imp arts energy to the gas being compressed by way of an input shaft moving a single or multiple rotating elements

[0771 Figures 1 through 7 show external views of an embodiment of die present invention in which a rotary compressor includes spring backed cam drive gate positioning system. Main bousing 100 includes a main casing 110 and end plates 120, each of which includes a hole through which drive shaft 1 40 passes axially. Liquid injector assemblies 130 are located on holes in die main casing 110.

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The ii min casing includes a hole for die inlet flange 160, and a hole for die gare casing 150.

[07 8) Gate casing 150 is connected to and positioned below main casing 110 at a hole in main casing 110. The gate casing 150 is comprised of two portions: an inlet side 152 and an oudet side 154. As shown in Figure 28, die oudet side 154 includes oudet ports 485, which are holes which lead to oudet valves 440. Alternatively, an outlet valve assembly may be used.

[079) Referring back to Figures 1-7, the spring-backed cam drive gate positioning system 200 is attached to the gate casing 150 and drive shaft 140. The gate positioning system 200 moves gate 600 in conjunction with the rotation of rotor 500. A movable assembly includes gate stints 210 and cam shuts 230 connected to gate support arm 220 and bearing support plate 156. The bearing support plate 156 seals the gate casing 150 by interfacing with the inlet and oudet sides through a bolted gasket connection. Bearing support plate 156 is shaped to seal gate casing 150, mount bearing housings 270 in a sufficiently parallel manner, and consoain compressive springs 280. Bearing housings 270, also known as pillow blocks, are concentric to die gate struts 210 and die cam stints 230.

[080) Two cam followers 250 are located tangentially to each cam 240, providing a downward force on die gate. Drive shaft 140 turns cams 240, which transmits force to die cam followers 250. The cam followers 250 may be mounted on a through shaft, which is supported on bodi ends, or cantilevered and only supported on one end. The cam followers 250 are attached to cam follower supports 260, which transfer die force into the cam struts 230. As cams 240 turn, the cam followers 250 are pushed down, thus moving the cam struts 230 down. This moves die gate support arm 220 and die gate strut 210 down. This, in turn, moves die gate 600 down.

[0811 Springs 280 provide a restorative upward force to keep die gate 600 timed appropriately to seal against die rotor 500. As die cams 240 continue to turn atid tio longer effectuate a downward force on die cam followers 250, springs 280 provide an upward force. As shown in diis embodiment, compression springs are utilized. As one of ordinary skill in the ait would appreciate, tension springs and tlie

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PCT/US2011/049599 shape of die bearing support plate 156 may be altered to provide for die desired upward or downward force. The upward force of die springs 280 pushes the cam follower support 260 and thus the gate support arm 220 up which in turn moves the gate 600 up.

[082) Due to die varying pressure angle between die cam followers 250 and cams 240, die preferred embodiment may utilize an exterior cam profile dial differs from die rotor 500 profile. This variation in profile allows tor compensation for die changing pressure angle to ensure diat the tip of die gate 600 remains proximate to the rotor 500 throughout die entire compression cycle.

[083J Line A in Figures 3, 6, and 7 shows die location for die crosssectional view- of die compressor in Figure 8. As shown in Figure 8, die main casing 110 has a cylindrical shape. Liquid injector housings 132 are attached to, or may be cast as a part of, die main casing 110 to provide for openings in the rotor casing 400. Because it is cytindrically shaped tn diis embodiment, die rotor casing 400 may also be referenced as die cylinder. The interior wall defines a rotor casing volume 410. The rotor 500 concentrically rotates with drive shaft 140 and is affixed to the drive shaft 140 by way of key 540 and press fit.

[084) Figure 9 shows an embodiment of the present invention in which a timing belt widi spring gate positioning system is utilized. This embodiment 290 incorporates two timing belts 292 each of which is attached to die drive shaft 140 by way of sheaves 294, The timing belts 292 are attached (o secondary shafts 142 by way of sheaves 295. Gate strut springs 296 are mounted around gate struts. Rocker arms 297 are mounted to rocker arm supports 299. The sheaves 295 are connected to rocker arm cams 293 to push die rocker anus 297 down. As die inner rings push down on one side of die rocker aims 297, die odier side pushes up against die gate support bar 298. The gate support bar 298 pushes up agamst die gate stints and gate strut springs 296, This moves the gate up. The springs 296 provide a downward force pushing die gate down.

[085| Figures 10 through 17 show external views of a rotary- compressor embodiment utilizing a dual cam follower gate positioning system. The main housing 100 includes a main casing 110 and end plates 120, each of which includes

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PCT/US2011/049599 a hole through which a drive shaft 140 passes axially. Liquid injector assemblies 130 are located on holes in the main casing 110. The main casing 110 also includes a hole for the inlet flange 160 and a hole for the gate casing 150. The gate casing 150 is mounted to and positioned below the main casing 110 as discussed above.

[086) A dual cam follower gate positioning system 300 is attached to die gate casing 150 and drive shaft 140. The dual cam follower gate positioning system 300 moves die gate 600 in conjunction with the rotation ol die rotor 500. hi a preferred embodiment, die size and shape of die cams is nearly identical to die rotor in cross-sectional size and shape. In other embodiments, die rotor, cam shape, curvature, cam diickness, and variations in die thickness of die lip of die cam may be adjusted to account for variations in the attack angle of the cam follower. Further, large or smaller cam sizes may be used. For example, a similar shape but smaller size cam may be used to reduce roller speeds.

[087) A movable assembly includes gate struts 210 and cam struts 230 connected to gate support ann 220 and bearing support plate 156. In diis embodiment, the bearing support plate 157 is straight. As one of ordinary skill in die art w-outd appreciate, die bearing support plate can utilize different geometries, including structures designed to or not to perform sealing of the gate casing 150. In diis embodiment, die bearing support plate 157 selves to seal die bottom of die gate casing 150 through a bolted gasket connection. Bearing housings 270, also known as pillow blocks, aie mounted to bearing support plate 157 and are concentric lo the gate struts 210 and the cam shuts 230.

[088) Drive shaft 140 turns cams 240, which transmit force to the cam followers 250, including upper earn followers 252 and lower cam followers 254.

The cam followers 250 may be mounted on a through shah, which is supported on both ends, or cantilevered and only supported on one end. In tins embodiment, four cam followers 250 are used for each cam 240. Two lower cam followers 252 arc located below and follow the outside edge of the cam 240. They arc mounted using a through shaft. Two upper cam followers 254 are located above tfie previous two and follow die inside edge of the cams 240. They are mounted using a cantilevered connection.

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[0891 Tlic cam followers 250 are attached to cam follower supports 260, which transfer die force into the cant struts 230. As the cants 240 turn, the cant struts 230 move up and down. This moves the gate support arm 220 and gate stints 210 up and down, which in him, moves the gate 600 up and down.

[090) Line A in Figures 11,12, 15, and 16 show the location lor die crosssectional view of die compressor in Figure 17. As shown in Figure 17, die main casing 110 has a cylindrical shape. Liquid injector housings 132 are attached to or may be cast as a part of the mam casing 110 to provide for openings in die rotor casing 400. The rotor 500 concentrically rotates around drive shaft 140.

[091J An embodiment using a belt driven system 310 is shown in Figure 18. Timing belts 292 are connected to the drive shaft 140 byway of sheaves 294. The timing belts 292 are each also connected to secondary shafts 142 by way of anodier set of sheaves 295. The secondare shafts 142 drive die external cams 240, which are placed below⁷ die gate casing 150 in diis embodiment. Sets of upper and lower cam followers 254 and 252 are applied to die cams 240, which proeide force to die movable assembly including gate struts 210 and gate support arm 220. As one of ordinaiy skill in die art would appreciate, belts may be replaced by chains or odier materials.

[092[ An embodiment of die present invention using an offset gate guide system is shown in Figures 19 through 22 and 33. Oudet of die compressed gas and injected fluid is achieved through a ported gate system 602 comprised of two parts bolted together to allow for internal lightening features. Fluid passes through channels 630 in the upper portion of the gate 602 and travels to the lengthwise sides to outlet through an exhaust port 344 in a timed manner with relation to the angle of rotation ot die rotor 500 during die cycle. Discrete point spring-backed scraper seals 326 provide sealing of die gate 602 in die single piece gate casing 336. Liquid injection is achieved dirough a variety ol flat spray nozzles 322 and injector nozzles 130 across a variety’ of liquid injector port 324 locations and angles.

[0931 Reciprocating motion of the two-piece gate 602 is controlled through die use of an offset spring-backed cam follower control system 320 to achieve gate motion in concert with rotor rotation. Single cams 342 drive the gate system

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PCT/US2011/049599 downwards dirougli die transmission of force on die cam followers 250 through die cam shuts 338. This results in controlled motion of the. crossann 334, which is connected by bolts (some of which are labeled as 328) with the two-piece gate 602. The crossarm 334 mounted linear bushings 330, which reciprocate along the length of cam shafts 332, control die motion of die gate 602 and the crossann 334. The cam shafts 332 are fixed in a precise manner to die main casing through die use of cam shaft support blocks 340. Compression springs 346 are utilized to provide a returning force on the crossann 334, allowing die cam followers 250 to maintain constant rolling contact with the cams, thereby achieving controlled reciprocating motion of die two-piece gate 602.

[0941 Figure 23 shows an embodiment using a linear actuator system 350 for gate positioning. A pair of linear actuators 352 is used to drive die gate. In this embodiment, it is not necessary to mechanically link die drive shaft to the gate as widi odier embodiments. The linear actuators 352 are controlled so as to raise and lower die gate in accordance widi die rotation of die rotor. The actuators may be electronic, hydraulic, belt-driven, electromagnetic, gas-drivem, variable-friction, or odier means. The actuators may be computer controlled or controlled by other means.

[095j Figures 24A and B show a magnetic drive system 360. The gate system may be driven, or controlled, in a reciprocating motion through die placement o! magnetic field generators, whether they are permanent magnets or electromagnets, on any combination of the rotor 500, gate 600, and/or gate easing 150. The purpose of this system is to maintain a constant distance from the tip of the gate 600 to the suri ace of the rotor 500 at all angles throughout the cycle. In a preferred magnetic system embodiment, permanent magnets 366 are mounted into die ends of die rotor 500 and retained. In addition, permanent magnets 364 are installed and retained in die gate 600. Poles of die magnets arc aligned so that die magnetic force generated between die rotor’s magnets 366 and die gate’s magnets 364 is a repulsive force, forcing die gate 600 down dirougli out die cycle to control its motion and maintain constant distance. To provide an upward, returning force on the gate 600, additional magnets (not shown) are installed into die bottom of die

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PCT/US2011/049599 gate 600 and die bottom of die gate easing 150 to provide an additional repulsive force. The magnetic drive systems are balanced to precisely control the gate’s reciprocating motion.

[096) Alternative embodiments may use an alternate pole orientation to provide attractive forces between die gate and rotor on die top portion of die gate and attractive forces between the gate and gate casing on the bottom portion of the gate. In place of die lower magnet system, springs may be used to provide a repulsive force. In each embodiment, electromagnets may be used in place of permanent magnets. In addition, switched reluctance electromagnets may also be utilized. In anodier embodiment, e lectio magnets may be used only in die rotor and gate. Their poles may switch at each inflection point of die gate's travel during its reciprocating cycle, allowing diem to be used in an attractive and repulsive method.

[097) Alternatively, direct hydraulic or indirect hydraulic (hydropneumatic) can be used to apply motive force/energy to die gate to drive it and position it adequately. Solenoid or odier flow’ control valves can be used to feed and regulate die position and movement of the hydraulic or hydropneumatic elements.

Hydraulic force may be converted to mechanical force acting on die gate dirough die use of a cylinder based or direct hydraulic actuators using me mbranes/diaphragms.

[098) Figure 25 shows an embodiment using a scotch yoke gate positioning system 370. Here, a pair of scotch yokes 372 is connected lo die drive shaft and the bearing support plate. A roller rotates at a fixed radius with respect to tbe shaft.

The roller follows a slot within tbe yoke 372, which is constrained to a reciprocating motion. The yoke geometry can he manipulated to a speciKc shape that will result in desired gate dynamics.

[099) As one oi’ skill in die art would appreciate, diese alternative drive mechanisms do not require any particular number of linkages between die drive shaft and die gate. For example, a single spring, belt, linkage bar, or yoke could be used. Depending on tlie design implementation, more than two such elements could be used.

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[0100| Figures 26A-26F show a compression cycle of an embodiment utilizing a tip seal 620. As die drive, shaft 140 turns, the rotor 500 and gate strut 210 push up gate 600 so that it is timed with the rotor 500. As the rotor 500 turns clockwise, the gate 600 rises up until the rotor 500 is in the 12 o’clock position shown in Figure 26C. As tlie rotor 500 continues to turn, die gate 600 moves downward until it is back at the 6 o’clock position in Figure 26F. The gate 600 separates the portion of the cylinder that is not taken up by rotor 500 into two components: an intake component 412 and a compression component 414.

[01011 Figures 26A-F depict steady state operation. Accordingly, in Figure 26A, where die rotor 500 is in die 6 o’clock position, die compression volume 414, which constitutes a subset oi die rotor casing volume 410, already has received fluid, in Figure 26B, die rotor 500 has turned clockwise and gate 600 lias risen so diat die tip seal 620 makes contact with the rotor 500 to separate die intake volume 412, which also constitutes a subset of the rotor casing volume 410, from die compression volume 414. Embodiments using die roller tip 650 discussed below instead of tip seal 620 would operate similarly. As die rotor 500 turns, as shown further in Figures 26C-E, die intake volume 412 increases, die re by drawing in more fluid from inlet 420, while the compression volume 414 decreases. As die volume of die compression volume 414 decreases, the pressure increases. The pressurized fluid is dien expelled hy way of an oudet 430. At a point in the compression cycle when a desired liigh pressure is reached, the outlet valve opens and the high pressure fluid can leave the compression volume 414. In diis embodiment, the valve outputs both the compressed gas and the liquid injected into the compression chamber.

[0102| Figures 27A - 27 F show an embodiment in which die gate 600 does not use a dp seal. Instead, die gate 600 is dined to be proximate to die rotor 500 as it turns. The close proximity of the gate 600 to the rotor 500 leaves only a very small padi for high pressure fluid to escape. Close proximity in conjunction widi die presence of liquid (due to die liquid injectors 136 or an injector placed in die gate itself) allow die gate 600 to effectively create an intake fluid component 412 and

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a. compression component 414, Embodiments incorporating notches 640 would operate similarly,

[0103j Figure 28 shows a cross-sectional perspective view of the rotor casing 400, the rotor 500, and the gate 600. The inlet port 420 shows the path that gas ca n enter. The outlet 430 is comprised of several holes that sen e as outlet ports 435 that lead to outlet valves 440. The gate casing 150 consists of an inlet side 152 and an outlet side 154. A return pressure path (not shown) may be connected to tire inlet side 152 of die gate casing 150 and die inlet port 420 to ensure drat there is no back pressure build up against gate 600 due to leakage through die gate seals. As one of ordinary skill in dre art would appreciate, it is desirable to achieve a hermetic seal, although peifect hermetic sealing is not necessaiy.

[0104] Figure 29 shows an alternativ e embodiment in which flat spray liquid injector housings 170 are located on die main casing 110 at approximately the 3 o’clock position. These injectors can be used to inject liquid direedy onto dre inlet side of dre gate 600, ensuring drat it does not reach high temperatures. These injectors also help to provide a coating of liquid on die rotor 500, helping to seal the compressor.

[0105) As discussed above, the preferred embodiments utilize a rotor that concentrically rotates within a rotor casing. In dre preferred embodiment, die rotor 500 is a riglit cylinder widi a noil-circular cross-section drat runs die lengdi of die main casing 110. Figur e 30 shows a cross-sectional view of the sealing and ironsealing portions of the rotor 500. The profile of the rotor 500 is comprised of three sections. The radii in sections I and III are defined hv a cycloidal curve. This curve also represents the rise and fall of the gate and defines an optimum acceleration profile for die gate. Odier embodiments may use dill ere nt curve functions to define tire radius such as a double harmonic function. Section II employs a constant radius 570, winch corresponds to the maximum radius of the rotor. The minimum radius 580 is located at die intersection of sections I and III, at die bottom of rotor 500. In a preferred embodiment, Φ is 23.8 degrees. In alternative embodiments, oilier angles may be utilized depending on (he desired size of lire compressor, the desired acceleration of die gaLe, and desired sealing area.

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[0106] The radii of die rotor 500 in the prefeired embodiment can be calculated using the following functions:

<img src="CA2809945C_files/CA2809945C-2.png" style="width:195pt;height:53pt;" />

[0107) In a preferred embodiment, tire rotor 500 is symmetrical along one axis. It may generally resemble a cross-sectional egg shape. The rotor 500 includes a hole 530 in which the drive shaft 110 and a key 510 may be mounted. The rotor 500 has a sealing section 510, which is the outer surface of the rotor 500 corresponding to section II, and a non-sealing section 520, which is the outer surface of tire rotor 500 corresponding to sections I and III. Tire sections I and III have a smaller radius than sections II creating a compression volume.

[0108) The sealing portion 510 is shaped to correspond to tire curvature of the rotor casing 400, thereby creating a dwell seal that effectively minimizes communication between the outlet 430 and inlet 420. Physical contact is not required for the dwell seal. Instead, it is sufficient lo create a tortuous path dial minimizes the amount of fluid that can pass through. In a preferred embodiment, the gap between the rotor and the casing in this embodiment is less than 0.008 inches. As one of ordinary skill in the art would appreciate, this gap may be altered depending oti tolerances, bodi in machining die rotor 500 and rotor housing 400, temperature, niatenal properties, and other specific application requirements.

[0109) Additionally, as discussed below, liquid is injected into die compression chamber. By becoming entrained in die gap between die scaling portion 510 and die rotor casing 400, the liquid can increase the effectiveness of die dwell seal.

[0110) As shown in Figure 31 A, die rotor 500 is balanced with cut out shapes and countenveights. Holes, some of which are marked as 550, lighten die rotor 500. Counterweights, one of which is labeled as 560, are made of a denser

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PCT/US2011/949599 material titan the remainder of die rotor 500. The shapes of die counterweights eati vary and do not need to cylindrical.

[0111 j The rotor design provides several advantages. As shown in the embodiment of Figure 31 A, the rotor 500 includes 7 cutout holes 550 on one side and mo counterweights 560 on die odier side to allow the center of mass to match die center of rotation. Ati opening 530 includes space for die drive shaft and a keys d'his weight distribution is designed to achieve balanced, concentric motion. The number and location of cutouts and counterweights may be changed depending on structural integrity', weight distribution, and balanced rotation parameters.

[0112| The cross-sectional shape of die rotor 500 allows for concentric rotation about the drive shaft’s axis of rotation, a dwell seal 510 portion, and open space on die non-sealing side for increased gas volume for compression.

Concentric rotation provides for rotation about die drive shaft’s principal axis of rotation and dius snioodier motion and reduced noise.

[0113| An alternative rotor design 502 is shown in Figure 3IB. In diis embodiment, a different arc of curvature is implemented utilizing three holes 550 and a circular opening 530. An odier alternative design 504· is shown in Figure 31C. Here, a solid rotor shape is used and a larger hole 530 (for a larger drive shaft) is implemented. Yet another alternative rotor design 506 is shown in Figure 31D incorporating an asymmetrical shape, which would smoodi die volume reduction curve, allowing for increased time for heat transfer to occur at higher pressures. Alternative rotor shapes may be implemented for different curvatures or needs for increased volume in the compression chamber,

[0114| The rotor surface maybe smooth m embodiments with contacting tip seals to minimize wear on the dp seal. In alternative embodiments, it may be advantageous to put surface texture on die rotor to create turbulence tiiat may improve the performance of non-contacting seals. Iti odier embodiments, die rotor casing’s interior cylindrical wall may further be textured to produce additional turbulence, both for sealing atid heat transfer benefits. This texturing could be achieved through machining of die parts or by* utilizing a surface coating. Ano die r

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PCT/US2011/949599 method of achieving the textuie would be through blasting widi a wateijet, sandblast, or similar device to create an irregular surface.

[0115j The main casing 110 may further utilize a removable cylinder liner. This liner may feature microsurfacing to induce turbulence for the benefits noted above. The liner may also act as a wear surface to increase the reliability' ofthe rotor and casing. The removable liner could be replaced at regular intervals as pan of a recommended maintenance schedule. The rotor may also include a liner.

[0116| The exterior of the main casing 110 may also be modified to meet application specific parameters. For example, in subsea applications, die casing may require to be significantly thickened to withstand exterior pressure, or placed within a secondary pressure vessel. Other applications may benefit from the exterior of the casing haring a rectangular or square profile to facilitate mounting exterior objects or stacking multiple compressors. Liquid may be circulated in the casing interior to achieve additional heat transfer or to equalize pressure in die case of subsea applications for example.

[0117| As shown in Figure 32A and B, die combination of die rotor 500 (here depicted widi rotor end caps 590), die gate 600, and drive shaft 140, provide for a more efficient manner of compressing fluids in a cylinder. The gate is aligned along die lengdi of die rotor to separate and define die inlet portion and compression portion as die rotor turns.

[0118 J The drive shaft 140 is mounted to endplates 120 in the preferred embodiment using one spherical roller bearing in each endplate 120. More than one bearing may be used in each endplate 120. in order to increase total load capacity. A grease pump (not shown) is used to provide lubrication to the bearings. Various types of other bearings may be utilized depending on application specific parameters, including roller bearings, ball bearings, needle bearings, conical bearings, cylindrical bearings, journal bearings, etc. Different lubrication systems using grease, oil, or other lubricants may also be used. Further, dry lubrication systems or materials may be used. Additionally, applications in which dynamic imbalance may occur may benefit from multi-bearing arrangements to support stray axial loads.

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[0119) Ope ratio π of gates in accordance with embodiments of die present invention are shown in Figures 8, 17, 22, 24B, 26A-F, 27À-F, 28, 32A-B, and 33-36. As shown in Figures 26A-F and 27A-F, gate 600 creates a pressure boundary between an intake volume 412 and a compression volume 414. Tire intake volume 412 is in communication widi the inlet 420. The compression volume 414 is in communication with the outlet 430. Resembling a reciprocating, rectangular piston, die gate 600 rises and falls in time widi the turning of tire rotor 500.

[0120| The gate 600 may include an optional tip seal 620 diat makes contact widi the rotor 500, providing an interface between the rotor 500 and die gate 600. Tip seal 620 consists of a strip of material at the tip of die gate 600 diat rides against rotor 500. The tip sea! 620 could be made of different materials, including polvmers, graphite, and metal, and could take a variety of geometries, such as a curved, flat, or angled surface. The tip seal 620 may be backed by pressurized fluid or a spring force provided by springs or elastomers. This provides a return force to keep die tip seal 620 in sealing contact widi the rotor 500.

[0121 j Different types of contacting tips may be used with the gate 600. As shown in Figure 35, a roller tip 650 may be used. The roller tip 650 rotates as it makes contact widr the turning rotor 500. Also, tips of differing strengths may be used. For example, a tip seal 620 or roller tip 650 may be made of softer metal tliat would gradually wear down before die rotor 500 surfaces would wear.

[0122) Alternatively, a non-contacting seal may be used. Accordingly, the (ip seal may be omitted. In these embodiments, the topmost portion of the gate 600 is placed proximate, but not necessarily in contact with, the rotor 500 as it turns. The amount of allowable gap may be adjusted depending on application pa ta meters.

[0123) As shown in Figures 34A and 34B, in an embodiment in which die tip of die gate 600 does not contact the rotor 500, die tip may include notches 640 tliat setve to keep gas pocketed against the tip of the gate 600. The entrained fluid, in cither gas or liquid form, assists in providing a non-contacting seal. As one of ordinary skill in the ait would appreciate, die number and size of the notches is a matter of design choice dependent on die compressor specifications.

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[0124| Alternatively, liquid may be injected from tlie gate itself. As shown in Figure 36, a cross-section a! view of a portion of a gate, one or more channels 660 from which a fluid may pass may be built into the gate. In one such embodiment, a liquid ran pass through a plurality of channels 660 to form a liquid seal between the topmost portion of die gate 600 and die rotor 500 as it turns. In another embodiment, residual compressed fluid may be inserted through one or more channels 660. Further still, die gate 600 may be shaped to match die curvature of portions of the rotor 500 to minimize the gap between die gate 600 and die rotor 500.

[01251 Preferred embodiments enclose die gate in a gate casing. As shown in Figures 8 and 17, die gate 600 is encompassed by the gate casing 150, including notches, one of which is shown as item 158. The notches hold die gate seals, which ensure diat the compressed fluid will not release from die compression volume 41T through die interface between gate 600 and gate casing 150 as gate 600 moves up and down. The gate seals may be made of various materials, including polymers, graphite or metal. A variety of different geometries may be used for these seals. Various embodiments could utilize different notch geometries, including ones in which the notches may pass through the gate casing, in part or in full.

[0126| Tlie seals may use energizing forces provided by springs or elastomers widi die assembly of die gale casing 150 inducing compression on die seals. Pressurized fluid may also be used lo energize the seals.

[0127| A rotor face seal may also be placed on the rotor 500 to provide for an interface between the rotor 500 and the endplates 120, An outer rotor face seal is placed along the exterior edge of the rotor 500, preventing fluid from escaping past die end ol die rotor 500. A secondary inner rotor face seal is placed oil die rotor face at a smaller radius to prevent any fluid that escapes past die outer rotor face seal from escaping the compressor entirely. This seal may use the same or odicr materials as die gate seal. Various geometries may be used to optimize flic effectiveness of the seals. These seals may use energizing forces provided by springs, elastomers or pressurized fluid.

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[0128| Minimizing die possibility' of fluids leaking to die exterior of die main housing 100 is desirable. Various seals, such as gaskets and o-rings, are used to seal external connections between parts. For example, in a preferred embodiment, a double ο-rîng seal is used between the main casing 110 and endplates 120. Further seals are utilized around the drive shaft 140 to prevent leakage of any fluids making it past the rotor face seals. A lip seal is used to seal die dnve shaft 140 where it passes dirough die endplates 120. Other forms of seals could also be used, such as mechanical or labvrindi seals.

[01291 It is desirable to achieve near isothermal compression. To provide cooling during the compression process, liquid injection is used. In preferred embodiments, the liquid is atomized to provide increased surface area for heat absorption. In other embodiments, different spray applications or odier means of injecting liquids maybe used.

[0130| Liquid injection is used to cool die fluid as it is compressed, increasing the efficiency of die compression process. Cooling allows most of die input energy⁷ to he used for compression radier than heat generation in the gas. The liquid has dramatically superior heat absorption characteristics compared to gas, allowing the liquid to absorb heat and minimize temperature increase of die working fluid, achieving near isothermal com press ion. As shown in Figures 8 and 17, liquid injector assemblies 130 are attached to die main casing 110. Liquid injector housings 132 include an adapter for (he liquid source 134 (if it is not included widi the nozzle) and a nozzle 136. Liquid is injected by way of a nozzle 136 directly into fhe rotor casing volume 410.

[0131( The amount and timing of liquid injection may lie controlled by a variety of implements including a computer-based controller capable of measuring die liquid drainage rate, liquid levels in die chamber, and/or any rotational resistance due to liquid accumulation through a variety of sensors. Valves or solenoids may be used in conjunction with the nozzles to selectively control injection timing. Vanable orifice control may also be used to regulate the amount of liquid injection and odier characteristics.

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[0132| Analytical anti experimental results are used to optimize die number, location, and spray direction of the injectors 136, These injectors 136 may be located in the periphery of the cylinder. Liquid injection may also occur through the rotor or gate. Tlie current embodiment of the design has two nozzles located at 12 o’clock and 10 o’clock. Different application parameters will also influence preferred nozzle arrays.

[0133J '1'he nozzle array is designed for a high flow rate of greater dian 5 gallons per minute and to be capable of extremely small droplet sizes of 150 microns or less at a low differential pressure ofless than 100 psi. Two exemplary nozzles are Spraying Systems Co. Part Number: 1/4HHSJ-SS12007 and Bex Spray Nozzles Part Number 1/4YS12007. The preferred flow rate and droplet size ranges will vary widi application parameters. Alternative nozzle styles may also be used. For example, one embodiment may use micro-perforations in the cylinder through which to inject liquid, counting on the small size of die holes to create sufficiendy small droplets. Other embodiments may include various off die shelf or custom designed nozzles which, when combined into an array, meet the injection requirements necessary for a given application.

[0134j As discussed above, the rate of heat transfer is improved by using such atomizing nozzles to inject very small droplets of liquid into die compression chamber. Because die rale of heat transfer is proportional to die surface area of liquid across which heat transfer can occur, the creation ol smaller droplets improves cooling. Numerous cooling liquids may be used. For example, water, triethvlene glycol, and various types of oils and other hydrocarhons may he nsed. Ethylene glycol, propylene glycol, methanol or other alcohols in case phase change characteristics are desired may be used. Refrigerants such as ammonia and odiers may also be used. Furdier, vanous additives may be combined widi die cooling liquid to achieve desired charactcnstics. Along with the heat transfer and heat absorption pro perdes of die liquid helping to cool die compression process, vaporization of the liquid may also be utilized in some embodiments of the design to take advantage of die large cooling effect due to phase change.

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[0135| Tlie effect of liquid coalescence is also addressed in die preferred embodiments. Liquid accumulation can provide resistance against the coinpressing mechanism, eventually resulting in hydiolock in which all motion of the compressor is stopped, causing potentially irreparable barm. As is shown m the embodiments of Figures 8 and 17, die inlet 420 and outlet 430 are located at die bottom of die rotor casing 400 on opposite sides of die gate 600, thus providing an efficient location for bodi intake ot fluid to be compressed and exhausting of compressed OuLd and die injected liquid. Λ valve is not necessary at the inlet 420. The inclusion of a dwell seal allows die inlet 420 to be an open port, simplifying die system and reducing inefficiencies associated widi inlet s alves. However, if desirable, an inlet valve could also be incorporated. Additional features may be added at die inlet to induce turbulence to protide enhanced thermal transfer and odier benefits. Hardened materials may be used at the inlet and other locations of die compressor to protect against captation when liquid/gas mixtures enter into choke and other cavitation-inducing conditions.

[0136j Alternative embodiments may include an inlet located at positions odier dian shown in die figures. Additionally, multiple inlets may be located along die periphery of die cylinder. These could be utilized in isolation or combination to accommodate inlet streams of varying pressures and flow rates. The inlet ports can also be enlarged or moved, eidier automatically or manually, to vary die displacement of the compressor,

[0137| In these embodiments, multi-phase compression is utilized, thus the outlet system allows for the passage of both gas and liquid. Placement of outlet 430 near the bottom of the rotor casing 400 provides for a drain for the liquid. This minimizes die risk of hydi olock found in odier liquid injection compressors. A small clearance volume allows any liquids Üiat remain within die chamber to be accommodated. Gravity assists in collecting and eliminating die excess liquid, preventing liquid accumulation over subsequent cycles. Additionally, die sweeping motion of die rotor helps to ensure diat most liquid is removed from die compressor during each compression cycle.

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[0138| Outlet valves allow gas anti liquid to flow out of die compressor once die desired pressure within the compression chamber is reached. Due to the presence of liquid in the working fluid, valves that minimize or eliminate changes in direction for the outflowing world ng fluid aie desirable. This prevents the hammering effect of liquids as they change direction. Additionally, it is desirable to minimize clearance volume.

[0139| Reed valves may be desirable as oudet valves. As one of ordinary skill in the art would appreciate, other types of valves known or as yet unknown may be utilized. Hoerbiger type R, CO, and Reed valves may be acceptable.

Additionally, CT, HDS, CE, CM or Poppet valves may be considered. Other embodiments may' use valves in odier locations in die casing dial allow' gas to exit once die gas has reached a given pressure. In such embodiments, various styles of valves may' be used. Passive or directly-actuated valves may be used and valve controllers may also be implemented.

[01401 In die presendy preferred embodiments, die oudet valves are located tiear the bottom of die casing and serve to allow exhausting of liquid and compressed gas from die high pressure portion. In odier embodiments, it may be useful to provide additional oudet valves located along periphery of main casing in toc a dons other dian near die bottom. Some embodiments may also benefit from oudels placed on die endplates. In still odier embodiments, it may be desirable Lo separate the outlet valves into two types ol valves - one predominately lor high pressured gas, the other for liquid drainage. In diese embodiments, die two or more types of valves may be located near each other, or in diflerent locations.

[0141 [ As shown in Figures 8 and 17, the sealing portion 510 of the rotor effectively precludes fluid comm un ica don between die oudet and inlet ports by way of die creation of a dwell seal. The interface between die rotor 500 and gate 600 further precludes fluid communication between die outlet and inlet ports through use of a non-contacting seal or dp seal 620. In diis way, die compressor is able to prevent any return and venting of fluid even when running at low speeds. Existing rotary compressors, when running at low speeds, have a leakage padi from die outlet

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PCT/US2011/049599 to die inlet and thus depend on die speed of rotation to minimize venting/leakage losses through tliis flowpath.

[0142) Tlie high pressure working fluid exerts a large horizontal force on the gate 6()0. Despite die rigidity- of the gate struts 210, this force will cause the gate 600 to bend and press against die inlet side of die gate casing 152. Specialized coatings dial are very hard and have haw coefficients of friction can coat bodi surfaces to minimize friction and wear from the sliding ol die gate 600 against die gate casing 152. Λ fluid bearing can also be utilized. Alternatively, pegs (not shown) can extend from die side of die gate 600 into gate casing 150 to help support the gate 600 against this horizontal force.

[0143) The large horizontal forces encountered by the gate may also require additional considerations to reduce sliding friction of die gate’s reciprocating motion. Various types of lubricants, such as greases or oils may be used. These lubricants may furdrer be pressurized to help resist the force pressing the gate against the gate casing. Components may also provide a passive source of lubrication for sliding parts via lubricant-impregnated or self-lubricating materials.

In die absence of, or in conjunction with, lubrication, replaceable wear elements may be used on sliding parts to ensure reliable operation contingent on adherence to maintenance schedules. As one of ordinary skill in tire art would appreciate, replaceable wear elements may also be utilized oil various odier wear surfaces wkliiu the compressor.

[0144) The compressor structure may be comprised of materials such as aluminum, carbon steel, stainless steel, titanium, tungsten, or brass. Materials may be chosen based on corrosion resistance, strength, density, and cost. Seals may lie comprised of polymers, such as PTFE, IIDPE, PEEK™, acetal copolymer, etc., graphite, cast iron, or ceramics. Odier materials known or unknown may be utilized. Coatings may also be used to enhance material properties.

[0145) As one of ordinary skill in the art can appreciate, various techniques may be utilized to manufacture and assemble tlie invention that may affect specific features of die design. For example, the main casing 110 may be manufactured using a casting process. In this scenario, die nozzle housings 132, gate casing 150,

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PCT/US2011/049599 oi' other components may be formed in singularity with die main casing 110. Similarly, the rotor 500 and drive shaft 140 may he built as a single piece, either due to strength requirements or chosen manufacturing technique.

[0146] Further benefits may be achieved by utilizing elements exterior to the compressor envelope. A flywheel may be added to the drive shaft 140 to smooth the torque curve encountered during the rotation. A flywheel or other exterior shaft attachment may also be used to help achieve balanced rotation. Applications requiring multiple compressors may combine multiple compressors on a single drive shaft with rotors mounted out of phase to also achieve a smoothened torque curve. A bell housing or other shaft coupling may be used to attach die drive shaft to a driving force such as engine or electric motor to minimize effects of misalignment and increase torque transfer efficiency. Accessory components such as pumps or generators may be dnve;i by the drive shaft using belts, direct couplings, gears, or odier transmission mechanisms. Timing gears or belts may furtlier be utilized to synchronize accessory components where appropriate.

[01471 After exiting the valves the mix of liquid and gases may be separated dirough any of die following methods or a combination thereof: 1. Interception through die use of a mesh, vanes, intertwined fibers; 2. inertial impaction against a surface; 3. Coalescence against odier larger injected droplets: 4. Passing dirough a liquid curtain; 5. Bubbling llirough a liquid reservoir; 6. Brownian motion to aid in coalescence; 7. Change in direction; 8. Centrifugal motion for coalescence into walls and other structures; 9.1 ne ilia change by rapid deceleration; and 10. Dehydration dirough the use of adsorbents or absorbents.

[0148( At the outlet of the compressor, a pulsation chamher may consist of cylindrical bottles or other cavities and elements, may be combined with any of the aforementioned separation methods to achieve pulsation dampening and attenuation as well as primary or final liquid coalescence. Other methods of separating die liquid and gases may be used as well.

[01491 The presendy preferred embodiments could be modified to operate as an expander. Furtlier, although descriptions have been used to describe die top and bottom and other directions, the orientation of die elements (e.g. the gate 600 at

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PCT/US2011/049599 die bottom of die rotor casing 400) should not be inteipreted as limitations on die present invention.

[0150( While the foregoing written description of the invention enables one of ordinary skill to make and use what is considered presently to he the best mode

Üiereof, diose of ordinary skill will understand and appreciate die existence of variations, combinations, and equivalents of die specific embodiment, method, and examples herein. The invention should therefore not be limited by die above described embodiment, mcdiod, and examples, but by all embodiments and methods within the scope and spirit of the invention.

[0151 j It is therefore intended dial die foregoing detailed description be regarded as illustrative radier than limiting, and that it be understood that it is die following claims, including all equivalents, Üiat are intended to define die spirit and scope of this invention. To the extent that “at least one” is used to highlight die possibility of a plurality of elements diat may satisfy a claim element, diis should not be interpreted as requiring “a” to mean singular only. “A” or “an” element may still be satisfied by a plurality of elements unless otherwise stated.

-32Claims:

1. A positive displacement compressor, comprising a compression chamber (410), including a rotor casing (400) that includes a compression chamber (410) having a first end. a second end, and an inner curved surface;

s shaft (140) located axially in the compression chamber (410):

a rtoh-clrcular rotor (500, 502, 504, 50S) mounted for rotation with the shaft (140) relative to the rotor casing (400), the non-circular rotor (500. 502. 504. 506) having a sealing portion (510). the sealing portion (5101 having a curved surface that corresponds with the inner curved surface of Ihe compression chamber (410), and a non-sealing portion; and a gate (600) having a first end and a second end. and being cperabie to move relative to the rotor casing to locate the first end proximate the rotor as the rotor rotates

2. The positive displacement compressor of claim 1, further comprising at least one liquid injection nozzle (150 136 322) located to provide injected fluids into the compression chamber (410). wherein the at least one liquid injection nozzle (130. 136. 322j is configured to provide an atomized liquid spray

3. The positive displacement compressor of claim 1, wherein:

the rotor (300, 502, £04. 506) has a first end and a second end aligned horizontally;

tne gate (500) is locatae at the bottom of the casing (400) and operable to move up and down an inlet (420) is located on the casing (400) on one side of the gaie (GOO); and an outlet port (430) is located on the casing (400) on tne opposite sice of the gate (GOO) ’he positive displacement compressor of claim 1, wherein the compressor is configured to be oriented such that the rotor (5Q0. 5Û2. 504. 506) rotates about a horizontal axis during operation of the compressor.

5. The positive displacement ccmpressor of claim 1. further comprising a gate positioning system (200, 3CQ, 370), the gate positioning system (200, 300. 370) operable to locate the first end of the gate (600) proximate tc the non-circular rotor (500. 502, 504, 505) as the rotor ¢500, 502 504, 506) turns, wherein a portion of the gete positioning system (200. 300. 370) is disposed outside of the compression chamber (4 W).

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