GB2486503A

GB2486503A - Single screw expander

Info

Publication number: GB2486503A
Application number: GB1102036.9A
Authority: GB
Inventors: Jean Louis Picouet; Wayne Wehber
Original assignee: Vilter Manufacturing LLC
Current assignee: Copeland Industrial LP
Priority date: 2010-12-17
Filing date: 2011-02-07
Publication date: 2012-06-20
Anticipated expiration: 2031-02-07
Also published as: GB2486503B; GB201102036D0

Abstract

A single screw expander comprises a housing and a slide valve assembly 21. A flow of oil 57 is introduced into the housing on the inlet side of the expander via a channel 55, and the flow is redirected by a surface 56 of a slide valve assembly such that it is substantially in line with a gas flow 42 through the inlet side of the expander. The expander may be single screw compressor being used as an expander. The expander may further comprise a pair of toothed star rotors which engage with a main rotor mounted within a cylindrical bore. The oil introduction channel is preferably in an inlet side of at least one expansion chamber. The gas flowing through the expander may be ammonia. The main rotor may drive a shaft, which drives a machine such as an electric generator.

Description

I

SINGLE SCREW EXPANDER

FIELD OF THE INVENTION

[0001] The present invention relates generally to expanders. In one aspect, the present invention relates to single screw expanders used as drive sources. In another aspect, the present invention relates to single screw expanders having oil injection.

BACKGROUND OF THE INVENTION

[0002] Compressors are used, for example, in compression systems (e.g., refrigeration systems) to compress refrigerant gas, such as "Freon", ammonia, natural gas, or the like. One type of compressor is a single screw gas compressor. This type of compressor employs a housing in which a motor-driven single main rotor having spiral grooves thereon meshes with a pair of gate or star rotors on opposite sides of the rotor to define gas compression chambers. The housing is provided with two gas suction ports (one near each gate rotor) and with two gas discharge channels (one near each gate rotor). Two dual slide valve assemblies are provided on the housing (one assembly near each gate rotor) and each slide valve assembly comprises a suction (also referred to as a "capacity slide valve") and a discharge slide valve (also referred to as a "volume slide valve") for controlling an associated intake channel and an associated discharge channel, respectively.

[0003] Further, the single screw compressor provides several specific benefits over various other compressors. For example, since the dual star rotors are situated opposite each other with respect to the main rotor, their rotational forces substantially cancel each other, thereby providing a more balanced load at the bearings that support the main rotor. The balanced load in turn results in less vibration about the compressor and a lower load on the bearings. In addition, the single screw compressor typically utilizes a metallic main rotor and non-metallic star rotors, thereby reducing the operational wear between these components and therefore reducing the overall lubrication requirements. U.S. Patents 4,610,612 and 4,610,613, as well as U.S. Patent Publications 2008/0206075 and 2008/0240939 include information regarding the general operation of compressors, including single screw gas compressors, and the teachings of these patent and patent publications are each incorporated in their respective entirety by reference herein.

[0004] It is well understood that a compressor can be operated in reverse, so that it can operate as an expander. A compressor generally uses a drive source to output compressed gas. In contrast, an expander can use an input of compressed gas to operate as a drive source for another machine. It is also understood that, when a compressor is operated as an expander, its structural components generally function in the same manner, albeit reverse. Still, it is understood that, in order to accomplish such reverse operation, certain modifications must be made to a given compressor. While various types of compressors have been configured to operate as expanders (e.g., twin screw, scroll, etc.), significant further enhancement of single screw compressors operation as expanders (i.e., single screw expanders) is needed.

[0005] Therefore, it would be desirable to provide a single screw expander that can be used to operate as a drive source for another machine. Moreover, it would be desirable if a single screw compressor can be operated as a single screw expander, thereby incorporating various benefits (e.g., balanced load, etc.) of a single screw compressor as noted above.

SUMMARY OF THE INVENTION

[0006] In one aspect, the present invention relates to a single screw expander. The expander, in at least some embodiments, includes: a housing; a pair of star rotors mounted for rotation in the housing, each having a plurality of star rotor teeth; a cylindrical bore situated at least partially between the star rotors in the housing, the bore having a main rotor rotatably mounted therein, wherein the main rotor has one or more grooves that meshingly engage at least one of the gear teeth from each star rotor; a pair of gas expansion chambers created by a portion of each star rotor, a portion of the main rotor groove, and the cylindrical bore, wherein each gas expansion chamber includes an intake side and a discharge side associated with each star rotor; a slide valve assembly mounted in relation to the housing, the slide valve assembly including a slide valve assembly structure having an oil flow redirecting surface; at least one intake channel for providing compressed gas to the intake sides of the gas expansion chambers; at least one discharge channel for discharging at least partially expanded gas from the discharge sides of the gas expansion chambers; and a rotor shaft at least one of coupled to or formed from the main rotor, and the rotor shaft is rotated by the main rotor as the compressed gas is expanded by the gas expansion chambers and released from the discharge channels. In at least some embodiments, a flow of oil is introduced into the intake channel via a channel formed or otherwise provided in the housing and the flow of oil is redirected using the oil flow redirecting surface of the slide valve assembly structure to be in a direction that is in-line, or at least substantially in-line, with a flow of compressed gas, when the slide valve assembly structure is positioned in a desired location with respect to the channel formed or otherwise provided in the housing. Method of using and operating the expander are also disclosed.

[0007] In another aspect, a method of generating power from a single screw expander is disclosed. The method comprises: flowing compressed gas from at least one intake channel into the intake side of at least one gas expansion chamber, the gas expansion chamber including at least a portion of a grooved main rotor and a plurality of teeth from at least one star rotor; expanding the gas in the at least one gas expansion chamber as the gas moves from the higher pressure intake side of the gas expansion chamber to a lower pressure discharge side of the gas expansion chamber, thereby rotating the at least one star rotor and the grooved main rotor, wherein the main rotor thereby provides a rotational drive source; and injecting or otherwise introducing a flow of oil is introduced into the at least one intake channel via a channel formed or otherwise provided in the housing and redirecting the flow of oil using an oil flow redirecting surface formed or otherwise provided with a slide valve assembly structure that is part of a slide valve assembly mounted with respect to the housing, the flow of oil redirected to be in a direction that is in-line, or at least substantially in-line, with the flowing of compressed gas.

[0008] In another aspect, a method of operating a single screw compressor as a single screw expander is disclosed. The method comprises: flowing compressed gas into a discharge end of the compressor; introducing oil into the compressed gas prior to the compressed gas entering a gas compression chamber; expanding the higher pressure compressed gas as it passes through the gas compression chamber to a lower pressure suction end, the expansion of the gas thereby rotating a main rotor situated at least partially in the compression chamber; and discharging the gas through the suction end.

In at least some embodiments, the introduction of the a flow of oil is via a channel formed or otherwise provided in a housing of the compressor and further that the flow of oil is redirected using an oil flow redirecting surface of a slide valve assembly structure to be in a direction that is in-line, or at least substantially in-line, with the flowing of compressed gas.

[0009] Other embodiments, aspects, features, objectives and advantages of the present invention will be understood and appreciated upon a full reading of the detailed description and the claims that follow.

DESCRIPTION OF THE DRAWINGS

[00101 Features of the present invention which are believed to be novel are set forth with particularity in the appended claims. Embodiments of the invention are disclosed with reference to the accompanying drawings and are for illustrative purposes only. The invention is not limited in its application to the details of construction or the arrangement of the components illustrated in the drawings. The invention is capable of other embodiments or of being practiced or carried out in other various ways.

Like reference numerals are used to indicate like components. In the drawings: [00111 FIG. 1 is a top view, partly in cross-section and with portions broken away, of an exemplary expander, the expander employing a single screw rotor, a pair of star rotors and having dual slide valves (not visible) in accordance with at least some embodiments of the present invention; [0012] FIG. 2 is an enlarged cross-sectional view taken along line 2-2 of FIG. 1; [0013] FIG. 3 is a schematic view of FIG. 1 illustrating i) exemplary intake and discharge flow paths, ii) exemplary intake and discharge sides, and iii) exemplary intake and discharge channels; and [0014] FIG. 4 is a Mollier diagram depicting a theoretical expansion process for an expander.

[0015] FIG. 5 shows a schematic view of a portion of the expander shown FIG. 3, illustrating oil injection in accordance with alternative embodiments of the present invention.

[0016] FIG. 6 shows an exemplary slide valve assembly carriage structure for use with embodiments of the expander, such as the expander shown in FIG. 5.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0017] Referring to FIGS. 1 and 2, numeral 10 designates an exemplary embodiment of a single screw gas expander that can be used as a drive source. Expander 10 generally comprises an expander housing 12, a single main rotor 14 mounted for rotation in housing 12, and a pair of star-shaped gate or star rotors 16 and 18 mounted for rotation in housing 12 and engaged with main rotor 14. Expander 10 further includes two sets of exemplary slide valve assemblies 20 (only one shown) mounted in housing 12 and cooperable with main rotor 14 to control gas flow into and from the gas expansion chambers 35 on the main rotor 14.

[00181 Expander housing 12 includes a cylindrical bore 24 in which main rotor 14 is rotatably mounted. Bore 24 is open at its suction end 27 and is closed by a discharge end wall 29. Main rotor 14, which is generally cylindrical and has a plurality of helical grooves 25 formed therein defining gas expansion chambers 35, is provided with a rotor output shaft 26 which is rotatably supported at opposite ends on bearing assemblies 28 mounted on housing 12.

[0019] Expander housing 12 includes spaces 30 therein in which the star rotors 16 and 18 are rotatably mounted and the star rotors 16 and 18 are located on opposite sides (i.e., 180 degrees apart) of main rotor 14.

Each of the star rotors 16 and 18 has a plurality of gear teeth 32 and is provided with a star rotor shaft 34 which is rotatably supported at opposite ends on bearing assemblies 34A and 34B (FIG. 2) mounted on housing 12. Each of the star rotors 16 and 18 rotate on an axis which is perpendicular to and spaced from the axis of rotation of main rotor 14 and its teeth 32 extend through an opening 36 communicating with bore 24.

Each tooth 32 of each of the star rotors 16 and 18 successively engages a groove 25 in main rotor 14 and, in cooperation with the wall of bore 24 and specifically its end wall 29, defines a gas expansion chamber 35. The aforementioned engagement allows the star rotors 16 and 18 to drive the main rotor 14, and subsequently the rotor output shaft 26. The rotor output shaft 26 can be coupled with another machine (not shown) to thereby provide a drive source.

[0020] Referring now to FIG. 3, a schematic view of FIG. 1 is provided to further illustrate the operation of the expander 10. The expander 10 is configured to receive compressed gas at the intake channels 40 from an outside source, such as a condenser (not shown). The compressed gas travels along intake flow paths 42, through the slide assemblies 20 (only one shown) to the intake sides 44 of the gas expansion chambers 35.

More specifically, while not shown, each of the slide valve assemblies 20 generally comprises a slide valve carriage structure which is mounted in relation to the expander, typically in a rigid manner (e.g., by mounting screws). Each slide valve assembly further typically includes two movable slide valve members or mechanisms, for example, a capacity slide valve member and a volume slide valve member, and these slide valve members are slidably mounted on the carriage for movement, typically in a manner parallel to the axis of main rotor 14.

[0021] The compressed gas meets resistance at the intakes sides 44 of the gas expansion chambers 35 where the gear teeth 32 and the groove are engaged. As the pressure continues to build at the intake sides 44 of the gas expansion chambers 35, the pressure at the intake sides 44 exceeds the pressure at discharge sides 48 of the gas expansion chambers 35. To relieve this pressure, the main rotor 14 and star rotors 16, 18 begin to rotate to allow the compressed gas to expand in the gas expansion chambers 35, and then released at discharge sides 48 of the gas expansion chambers 35. The now expanded gas is relieved through discharge channels 50 and exits the housing 12, as shown along discharge paths 52. The expansion of the compressed gas results in the rotation of the main rotor 14 and subsequently the rotor output shaft 26.

The rotor output shaft 26 provides a rotating output that can be coupled to the input of other machines. In this manner the expander 10 can be used to drive various other machines.

[0022] During operation of the expander, oil is supplied to the gas expansion chambers 35 to provide an oil seal at points where the main rotor 14 meshes with the gate rotors 16, 18 and with the housing 12. In this way a proper seal is provided to minimize gas leakage in the gas expansion chambers 35. In addition, the oil serves as a cooling medium to counteract the heat transferred from the high pressure gas and the heat generated by friction of the main rotor 14, gate rotors 16, 18 and the housing 12 during operation. To provide adequate sealing and cooling throughout the gas expansion chambers 35, the oil is injected by at least one oil injection port 54 situated upstream of the gas expansion chambers.

This allows the oil to enter the compressed gas prior to exposure to the gas expansion chambers 35. In at least one embodiment, an oil injection port 54 is situated in each of the intake channels 40. In another embodiment, an oil injection port 54 is located adjacent to each of the intake sides 44 of the gas expansion chambers 35. To conserve the use of oil, oil that exits gas expansion chambers 35 and flows out of the discharge channels 50 is recovered and recirculated. Further, to facilitate proper injection of oil at an injection port 54, the oil is pressurized to exceed the pressure of the compressed gas in the intake channels 40.

[0023] FIG. 3 illustrates the flow path of the compressed gas as it enters the expander 10 and proceeds through the intake channels 40, wherein oil is injected into the gas by injection ports 54. Oil flow is perpendicular or substantially perpendicular to the compressed gas flow paths 42. The gas (now mixed with oil) then proceeds into the intake sides 44 (high pressure) of the gas expansion chambers 35, wherein the gas expands as it passes to the discharge sides 48 (low pressure), providing a rotational motion of the main rotor 14. The injected oil provides lubrication and sealing between the gear teeth 32 and the main rotor 14 during the expansion process. The gas then proceeds through the discharge channels 50 to exit the expander.

[0024] FIG. 4 is a Mollier diagram depicting a theoretical expansion process for an expander. Line A indicates a wet-wet condition, line B indicates a dry-wet condition, and line C indicates a dry-dry condition.

Desirably, a single screw expander, in accordance with at least some embodiments of the present invention, is capable of maintaining the compressed gas in a wet-wet condition inside the gas expansion chambers. In such cases, the expander requires less cooling than when the compressed gas is in a dry-wet or dry-dry condition.

[00251 With reference to FIG. 5, it can be seen that compressed gas flows through the expander, and more specifically, the intake channels 40 (one of which is shown) as previously described with reference to FIG. 3.

Oil was previously injected into the gas by ports 54 (still shown in FIG. 5, but in phantom) as noted earlier. However, in accordance with instant embodiments of the present disclosure, oil is introduced into the intake channels 40 via channels 55 (only one of which is shown) formed or otherwise provided in the expander housing 12. Flow of oil is indicated by arrow 57.

[0026] FIG. 6 shows an exemplary slide valve assembly structure 21 for use with embodiments of the expander, such as the expander shown in FIG. 5. More specifically, the slide valve assembly structure 21 (or "slide valve assembly carriage structure") can be used as part of, or in conjunction with, slide valve assemblies 20 described above with respect to FIGS. 1-3. Slide valve assembly structure 21 comprises a main portion 60 having a plurality of openings 62. As noted above, each slide valve assembly comprises a suction slide valve and a discharge slide valve (not shown), and the slide valves are positioned with respect to the openings 62 so as to control the associated intake or discharge channel, respectively.

[0027] With reference to FIGS. 5 and 6, the slide valve assembly structure 21 includes an angled surface 56 which is used to re-direct oil flow. As shown, angled surface or face 56 is positioned so that it is at an angle relative to the main rotor 14 (shown in FIG. 3). More specifically, a flow of oil, indicated by arrow, 57 is introduced into the intake channels 40 via channels 55 and, when the slide valve assembly structure 2lis positioned as shown with respect to the channels 55, the flow of oil 58 is redirected using angled surface 56 in a redirected oil flow, indicated by arrows 58, that is in-line, or at least generally in-line, with the compressed gas flow path 42 (shown in phantom). Stated another way, oil flows into channels 40 where the flow is intersected by the angled surface 56 of the slide valve assembly structure 21 is positioned in the appropriate or desired location.

Advantageously, all or substantially all of the flow of oil 57 is redirected in the redirected oil flow 58 corresponding to the compressed oil flow path 42 of the expander. In at least this way, the surface 56 can be termed an "oil flow redirecting surface". Such oil flow redirection advantageously repositions oil flow to the correct or desired locations within the expander, increasing overall efficiency of the expander with a reduced amount of oil compared to alternative arrangements.

[0028] Operationally, the oil is injected or otherwise introduced via at channels 55, and it is noted that these channels are situated upstream of the gas expansion chambers 35 (FIG. 3) so as to provide adequate sealing and cooling throughout the gas expansion chambers.

Advantageously, and in accordance with present embodiments, oil enters the compressed gas prior to exposure to the gas expansion chambers. As shown, channels 55 are situated adjacent and in fluid communication with intake channels 40. Oil that is introduced into the channels 40 is typically recovered (at least to a large extent) and recirculated. Further, to facilitate proper oil injection of oil at the channels 50, the oil is again pressurized to exceed the pressure of the compressed gas in the intake channels 40.

[0029] In accordance with at least some embodiments, angled surface 56 is generally planar so as to include or at least partially coincide with a plane 66, and the channel 55 is generally cylindrical so as to include or at least partially coincide with an axis 68. In at least some embodiments, angled surface plane 66 is oriented to be at between about 40 degrees and about 50 degrees with respect to the channel axis 68. More particularly, and again in at least some embodiments, angled surface plane 66 is oriented to be at between about 45 degrees with respect to the channel axis 68. Sizing of features will vary depending on a variety of factors, including overall expander size. For example, for a 900 CFM expander, the channel 55 can be sized to have a quarter inch (i.e., 1⁄4") diameter. Other geometries (e.g., non-planar or non-cylindrical) for the angled surface 56 and channel 55 are contemplated and considered within the scope of the present invention. In accordance with at least some embodiments, it is further noted that the angled surface 56 is formed by machining or machining out a portion of the slide valve assembly structure 21 and, more particularly, the main portion 60.

[0030] The expander 10 provides a versatile energy converter that can be powered by a multitude of heat sources and provides a rotating drive source that can power various machines. One example of a heat source that can be used to create the compressed gas is the exhaust of an electric generator. This generator exhaust may be used to heat a liquid such as ammonia in a condenser unit, thereby creating the pressurized/compressed gas. Although the pressure of the compressed gas can vary depending on the heat source, the size of the condensing unit, etc., a typical 240 millimeter size expander can provide enough rotational power at the rotor output shaft 26 to sufficiently drive a 300 kilowatt electric generator.

[0031] Further, the rotor output shaft 26 can drive various machines that are capable of utilizing a rotational input drive source, for example, an electric generator. In a more specific example, the expander 10 can utilize compressed gas generated from the exhaust of an electric generator to provide an output to drive another electric generator. Therefore, the wasted energy of driving one power generation source is recycled to provide the driving force for another power source.

[0032J In accordance with various embodiments of the present disclosure, an expander, such as a single screw expander, is disclosed.

The expander includes: a pair of star rotors mounted for rotation in a housing, each having a plurality of star rotor teeth; a cylindrical bore situated at least partially between the star rotors in the housing, the bore having a main rotor rotatably mounted therein, wherein the main rotor has one or more grooves that mesh ingly engage at least one of the gear teeth from each star rotor; a pair of gas expansion chambers created by a portion of each star rotor, a portion of the main rotor groove, and the cylindrical bore, wherein each gas expansion chamber includes an intake side and a discharge side associated with each star rotor; at least one intake channel for providing compressed gas to the intake sides of the gas expansion chambers; at least one discharge channel for discharging at least partially expanded gas from the discharge sides of the gas expansion chambers; and a rotor shaft at least one of coupled to or formed from the main rotor, wherein the rotor shaft is rotated by the main rotor as the compressed gas is expanded by the gas expansion chambers and released from the discharge channels. The expander can include at least one oil injection port that is situated upstream of the gas compression chambers for injecting oil into the compressed gas to provide at least one of cooling and sealing of at least a portion of the gas expansion chambers. The expander can include at least one oil injection port that is situated in the at least one intake chamber. The expander can include at least one oil injection port that is situated adjacent to the intake side of the gas expansion chambers. The compressed gas can be ammonia. The rotor output shaft of the expander, in at least some embodiments, can serve as the drive source of a machine, and in at least some embodiments, the machine can be an electrical generator. In at least one embodiment, the compressed gas can be generated from a condenser containing gas that is exposed to a heat source. The heat source can be a generator exhaust. The expander, in at least some embodiments, is capable of maintaining a wet-wet condition inside the gas expansion chambers. The expander, such as the single screw expander, can, in at least some embodiments, provide for a generator application as shown and/or described herein.

1100331 In accordance with various embodiments of the present disclosure, a method of generating power from an expander, such as a single screw expander, is disclosed. The method includes: flowing compressed gas from at least one intake channel into the intake side of at least one gas expansion chamber, the gas expansion chamber including at least a portion of a grooved main rotor and a plurality of teeth from at least one star rotor; and expanding the gas in the at least one gas expansion chamber as the gas moves from the higher pressure intake side of the gas expansion chamber to a lower pressure discharge side of the gas expansion chamber, thereby rotating the at least one star rotor and the grooved main rotor, wherein the main rotor thereby provides a rotational drive source. The method can further include injecting oil into the compressed gas at a location upstream of the at least one gas expansion chamber. The method can further include using an expander, such as the single screw expander, of the kind described herein.

[0034] In accordance with various embodiments of the present disclosure, a method of operating an compressor, such as a single screw compressor, as an expander, such as a single screw expander, the method including: flowing compressed gas into a discharge end of compressor; injecting oil into the compressed gas prior to the compressed gas entering a gas compression chamber; expanding the higher pressure compressed gas as it passes through the gas compression chamber to a lower pressure suction end, the expansion of the gas thereby rotating a main rotor situated at least partially in the compression chamber; and discharging the gas through the suction end.

[0035J In accordance with various embodiments of the present disclosure, a single screw expander is disclosed. The expander comprises: a housing; a pair of star rotors mounted for rotation in the housing, each having a plurality of star rotor teeth; a cylindrical bore situated at least partially between the star rotors in the housing, the bore having a main rotor rotatably mounted therein, wherein the main rotor has one or more grooves that mesh ingly engage at least one of the gear teeth from each star rotor; a pair of gas expansion chambers created by a portion of each star rotor, a portion of the main rotor groove, and the cylindrical bore, wherein each gas expansion chamber includes an intake side and a discharge side associated with each star rotor; a slide valve assembly mounted in relation to the housing, the slide valve assembly including a slide valve assembly structure having an oil flow redirecting surface; at least one intake channel for providing compressed gas to the intake sides of the gas expansion chambers; at least one discharge channel for discharging at least partially expanded gas from the discharge sides of the gas expansion chambers; and a rotor shaft at least one of coupled to or formed from the main rotor, and the rotor shaft is rotated by the main rotor as the compressed gas is expanded by the gas expansion chambers and released from the discharge channels; wherein a flow of oil is introduced into the intake channel via a channel formed or otherwise provided in the housing and the flow of oil is redirected using the oil flow redirecting surface of the slide valve assembly structure to be in a direction that is in-line, or at least substantially in-line, with a flow of compressed gas, when the slide valve assembly structure is positioned in a desired location with respect to the channel formed or otherwise provided in the housing. The channel formed or otherwise provided in the housing can be situated upstream of the gas expansion chambers, for injecting oil into the compressed gas to provide at least one of cooling and sealing of at least a portion of the gas expansion chambers. Oil flowing into the intake channel from the channel formed or otherwise provided in the housing can be intersected by the oil flow redirecting surface of the slide valve assembly structure that is positioned in the desired location such that all or substantially all of the flow of oil is redirected to be in a direction corresponding to the flow of compressed gas. The channel formed or otherwise provided in the housing can be situated adjacent to the intake side of the gas expansion chambers. The single screw expander of any of claims I to 4, wherein the compressed gas is ammonia. The rotor shaft can serve as the drive source of a machine which, in at least some embodiments, is an electrical generator. The compressed gas can be generated from a condenser containing gas that is exposed to a heat source which, in at least some embodiments, is a generator exhaust. The expander is, in at least some embodiments, capable of maintaining a wet-wet condition inside the gas expansion chambers.

[0036] In accordance with various embodiments of the present disclosure, a method of generating power from a single screw expander is disclosed. The method comprises: flowing compressed gas from at least one intake channel into the intake side of at least one gas expansion chamber, the gas expansion chamber including at least a portion of a grooved main rotor and a plurality of teeth from at least one star rotor; expanding the gas in the at least one gas expansion chamber as the gas moves from the higher pressure intake side of the gas expansion chamber to a lower pressure discharge side of the gas expansion chamber, thereby rotating the at least one star rotor and the grooved main rotor, wherein the main rotor thereby provides a rotational drive source; and injecting or otherwise introducing a flow of oil is introduced into the at least one intake channel via a channel formed or otherwise provided in the housing and redirecting the flow of oil using an oil flow redirecting surface formed or otherwise provided with a slide valve assembly structure that is part of a slide valve assembly mounted with respect to the housing, the flow of oil redirected to be in a direction that is in-line, or at least substantially in-line, with the flowing of compressed gas. The introduction of oil into the compressed gas can be at a location upstream of the at least one gas expansion chamber. The introduction of oil can take place when the slide valve assembly structure is positioned in a desired location with respect to the channel formed or otherwise provided in the housing. The oil flow redirecting surface can be or comprise an angled surface. The angled surface can be generally planar so as to include or at least partially coincide with a plane, and the channel can be generally cylindrical so as to include or at least partially coincide with an axis. The angled surface plane can be oriented to be at between about 40 degrees and about 50 degrees with respect to the channel axis. The angled surface plane can be oriented to be at about forty-five (45) degrees with respect to the channel axis.

[0037] In accordance with various embodiments of the present disclosure, a method of operating a single screw compressor as a single screw expander is disclosed. The method comprises: flowing compressed gas into a discharge end of the compressor; introducing oil into the compressed gas prior to the compressed gas entering a gas compression chamber; expanding the higher pressure compressed gas as it passes through the gas compression chamber to a lower pressure suction end, the expansion of the gas thereby rotating a main rotor situated at least partially in the compression chamber; and discharging the gas through the suction end; and wherein the introduction of the a flow of oil is via a channel formed or otherwise provided in a housing of the compressor and further that the flow of oil is redirected using an oil flow redirecting surface of a slide valve assembly structure to be in a direction that is in-line, or at least substantially in-line, with the flowing of compressed gas. The method can be accomplished using accomplished using an expander of the kind disclosed or claimed herein.

[0038] It is specifically intended that the present invention not be limited to the embodiments and illustrations contained herein, but include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims.

Claims

Claims 1. A single screw expander comprising: a housing; a pair of star rotors mounted for rotation in the housing, each having a plurality of star rotor teeth; a cylindrical bore situated at least partially between the star rotors in the housing, the bore having a main rotor rotatably mounted therein, wherein the main rotor has one or more grooves that meshingly engage at least one of the gear teeth from each star rotor; a pair of gas expansion chambers created by a portion of each star rotor, a portion of the main rotor groove, and the cylindrical bore, wherein each gas expansion chamber includes an intake side and a discharge side associated with each star rotor; a slide valve assembly mounted in relation to the housing, the slide valve assembly including a slide valve assembly structure having an oil flow redirecting surface; at least one intake channel for providing compressed gas to the intake sides of the gas expansion chambers; at least one discharge channel for discharging at least partially expanded gas from the discharge sides of the gas expansion chambers; and a rotor shaft at least one of coupled to or formed from the main rotor, and the rotor shaft is rotated by the main rotor as the compressed gas is expanded by the gas expansion chambers and released from the discharge channels; and wherein a flow of oil is introduced into the intake channel via a channel formed or otherwise provided in the housing and the flow of oil is redirected using the oil flow redirecting surface of the slide valve assembly structure to be in a direction that is in-line, or at least substantially in-line, with a flow of compressed gas, when the slide valve assembly structure is positioned in a desired location with respect to the channel formed or otherwise provided in the housing.
2. The single screw expander of claim 1, wherein the channel formed or otherwise provided in the housing is situated upstream of the gas expansion chambers, for injecting oil into the compressed gas to provide at least one of cooling and sealing of at least a portion of the gas expansion chambers.
3. The single screw expander of claims 1 or 2, wherein oil flowing into the intake channel from the channel formed or otherwise provided in the housing is intersected by the oil flow redirecting surface of the slide valve assembly structure that is positioned in the desired location such that all or substantially all of the flow of oil is redirected to be in a direction corresponding to the flow of compressed gas.
4. The single screw expander of any of claims I to 3, wherein the channel formed or otherwise provided in the housing is situated adjacent to the intake side of the gas expansion chambers.
5. The single screw expander of any of claims I to 4, wherein the compressed gas is ammonia.
6. The single screw expander of any of claims I to 5, wherein the rotor shaft serves as the drive source of a machine.
7. The single screw expander of claim 6, wherein the machine is an electrical generator.
8. The single screw expander of any of claims I to 7, wherein the compressed gas is generated from a condenser containing gas that is exposed to a heat source.
9. The single screw expander of claim 8, wherein the heat source is a generator exhaust.
10. The single screw expander of any of claims 1 to 9, wherein the expander is capable of maintaining a wet-wet condition inside the gas expansion chambers.
11. A method of generating power from a single screw expander, the method comprising: flowing compressed gas from at least one intake channel into the intake side of at least one gas expansion chamber, the gas expansion chamber including at least a portion of a grooved main rotor and a plurality of teeth from at least one star rotor; expanding the gas in the at least one gas expansion chamber as the gas moves from the higher pressure intake side of the gas expansion chamber to a lower pressure discharge side of the gas expansion chamber, thereby rotating the at least one star rotor and the grooved main rotor, wherein the main rotor thereby provides a rotational drive source; and injecting or otherwise introducing a flow of oil is introduced into the at least one intake channel via a channel formed or otherwise provided in the housing and redirecting the flow of oil using an oil flow redirecting surface formed or otherwise provided with a slide valve assembly structure that is part of a slide valve assembly mounted with respect to the housing, the flow of oil redirected to be in a direction that is in-line, or at least substantially in-line, with the flowing of compressed gas.
12. The method of claim 11, wherein the introduction of oil into the compressed gas is at a location upstream of the at least one gas expansion chamber.
13. The method of claims 11 or 12, wherein the introduction of oil takes place when the slide valve assembly structure is positioned in a desired location with respect to the channel formed or otherwise provided in the housing.
14. The method of any of claims 11 tol3, wherein the oil flow redirecting surface is an angled surface
15. The method of claim 14 wherein the angled surface is generally planar so as to include or at least partially coincide with a plane, and the channel is generally cylindrical so as to include or at least partially coincide with an axis.
16. The method of claim 15, wherein the angled surface plane is oriented to be at between about 40 degrees and about 50 degrees with respect to the channel axis.
17. The method of claim 16, wherein the angled surface plane is oriented to be at about forty-five (45) degrees with respect to the channel axis.
18. A method of operating a single screw compressor as a single screw expander, the method comprising: flowing compressed gas into a discharge end of the compressor; introducing oil into the compressed gas prior to the compressed gas entering a gas compression chamber; expanding the higher pressure compressed gas as it passes through the gas compression chamber to a lower pressure suction end, the expansion of the gas thereby rotating a main rotor situated at least partially in the compression chamber; and discharging the gas through the suction end; and wherein the introduction of the a flow of oil is via a channel formed or otherwise provided in a housing of the compressor and further that the flow of oil is redirected using an oil flow redirecting surface of a slide valve assembly structure to be in a direction that is in-line, or at least substantially in-line, with the flowing of compressed gas.
19. The method of any of claims 11 to 18, wherein the method is accomplished using the expander of claim 1.
20. A single screw expander as herein before described with reference to figures 1 to 3 and 5 and 6.