Multi-stage volumetric fluid expansion device

Abstract

A multi-stage expansion device is disclosed. In one embodiment, the multi-stage expansion device has a housing within which a first stage, a second stage, and a third stage are housed. The housing may also be configured with internal working fluid passageways to direct a working fluid from the first stage to the second stage and/or from the second stage to the third stage. Each of the stages may include a pair of non-contacting rotors that are mechanically connected to each other and to a power output device such that energy extracted from the working fluid is converted to mechanical work at the output device. In one embodiment, a step up gear arrangement is provided between the rotors of the first and second stages. A step up gear arrangement may also be provided between the rotors of the second and third stage.

What is claimed is: 
     
         1 . A multi-stage volumetric fluid expansion device comprising:
 a. a first fluid expansion stage having a first pair of non-contacting rotors disposed between a first inlet and a first outlet, the first fluid expansion stage being configured to generate useful work at the first pair of rotors by expanding a working fluid from a first pressure to a second pressure that is lower than the first pressure;   b. a second fluid expansion stage having a second pair of non-contacting rotors disposed between a second inlet and a second outlet, the second fluid expansion stage being configured to generate useful work at the second pair of rotors by receiving the working fluid from the first fluid expansion stage outlet and expanding the working fluid to a third pressure that is lower than the second pressure; and   c. a power output device rotated by the first and second pair of rotors.   
     
     
         2 . The multi-stage volumetric fluid expansion device of  claim 1 , further comprising:
 a. a housing within which the first and second pairs of rotors is disposed, wherein the first outlet and the second inlet are joined within the housing to form a continuous working fluid passageway extending between the first inlet and the second outlet .   
     
     
         3 . The multi-stage volumetric fluid expansion device of  claim 1 , wherein:
 a. one of the first pair of rotors and one of the second pair of rotors are mounted to a first common rotor shaft and the other of the first pair of rotors and the other of the second pair of rotors are mounted to a second common rotor shaft;   b. wherein the power output device is rotated by the first rotor shaft.   
     
     
         4 . The multi-stage volumetric fluid expansion device of  claim 3 , wherein:
 a. the first shaft is provided with a drive gear and the power output device is provided with an input gear that is driven by the drive gear.   
     
     
         5 . The multi-stage volumetric fluid expansion device of  claim 4 , wherein:
 a. the drive gear and input gear are configured in a step down arrangement such that the first and second pair of rotors rotates at a higher rotational speed than the power output device.   
     
     
         6 . The multi-stage volumetric fluid expansion device of  claim 5 , wherein:
 a. the power output device is provided with a clutch to selectively engage and disengage the first rotor shaft from the power output device.   
     
     
         7 . The multi-stage volumetric fluid expansion device of  claim 2 , wherein:
 a. one of the first pair of rotors is mounted to a first rotor shaft and the other of the first pair of rotors is mounted to a second rotor shaft; and   b. one of the second pair of rotors is mounted to a third rotor shaft and the other of the second pair of rotors is mounted to a fourth shaft;   c. wherein the power output device is rotated by the fourth rotor shaft.   
     
     
         8 . The multi-stage volumetric fluid expansion device of  claim 4 , wherein:
 a. the first shaft is provided with a first drive gear and the fourth shaft is provided with a first input gear that is driven by the first drive gear.   
     
     
         9 . The multi-stage volumetric fluid expansion device of  claim 5 , wherein:
 a. the first drive gear and first input gear are configured in a step up arrangement such that the first pair of rotors rotates at a lower rotational speed than the second pair of rotors.   
     
     
         10 . The multi-stage volumetric fluid expansion device of  claim 9 , wherein:
 a. the fourth shaft is provided with a second drive gear and the power output device is provided with an second input gear that is driven by the second drive gear.   
     
     
         11 . The multi-stage volumetric fluid expansion device of  claim 10 , wherein:
 a. The second drive gear and the second input gear are configured in a step down arrangement such that the second pair of rotors rotates at a higher rotational speed than the power output device.   
     
     
         12 . The multi-stage volumetric fluid expansion device of  claim 11 , wherein:
 a. the power output device is provided with a clutch to selectively engage and disengage the fourth rotor shaft from the power output device.   
     
     
         13 . The multi-stage volumetric fluid expansion device of  claim 1 , wherein:
 a. the second pair of rotors have twisted non-contacting lobes, wherein one of the second pair of rotors has a number of twisted lobes that equals a number of twisted lobes of the other of the second pair of rotors.   
     
     
         14 . A multi-stage volumetric fluid expansion device comprising:
 a. a first fluid expansion stage having a first pair of non-contacting rotors disposed between a first inlet and a first outlet, the first fluid expansion stage being configured to generate useful work at the first pair of rotors by expanding a working fluid from a first pressure to a second pressure that is lower than the first pressure;   b. a second fluid expansion stage having a second pair of non-contacting rotors disposed between a second inlet and a second outlet, the second fluid expansion stage being configured to generate useful work at the second pair of rotors by receiving the working fluid from the first fluid expansion stage outlet and expanding the working fluid to a third pressure that is lower than the second pressure;   c. a third fluid expansion stage having a third pair of non-contacting rotors disposed between a third inlet and a third outlet, the third fluid expansion stage being configured to generate useful work at third pair of rotors by receiving the working fluid from the second fluid expansion stage outlet and expanding the working fluid to a fourth pressure that is lower than the third pressure;   d. a power output device rotated by the first, second, and second third of rotors.   
     
     
         15 . The multi-stage volumetric fluid expansion device of  claim 14 , further comprising:
 a. a housing within which the first, second, and third pairs of rotors is disposed, wherein the second outlet and third inlet are joined within the housing to form a continuous working fluid passageway extending between the second inlet and the third outlet.   
     
     
         16 . The multi-stage volumetric fluid expansion device of  claim 15 , wherein:
 a. the first outlet and the second inlet are joined within the housing to form a continuous working fluid passageway extending between the first inlet and the third outlet.   
     
     
         17 . The multi-stage volumetric fluid expansion device of  claim 14 , wherein:
 a. one of the first pair of rotors, one of the second pair of rotors, and one of the third pair of rotors are mounted to a first common rotor shaft and the other of the first pair of rotors, the other of the second pair of rotors, and the other pair of rotors are mounted to a second common rotor shaft;   b. wherein the power output device is rotated by the first rotor shaft.   
     
     
         18 . The multi-stage volumetric fluid expansion device of  claim 15 , wherein:
 a. one of the first pair of rotors and one of the second pair of rotors is mounted to a first common rotor shaft and the other of the first pair of rotors and the other of the second pair of rotors is mounted to a second common rotor shaft; and   b. one of the third pair of rotors is mounted to a third rotor shaft and the other of the third pair of rotors are mounted to a fourth rotor shaft;   c. wherein the power output device is rotated by the fourth rotor shaft.   
     
     
         19 . The multi-stage volumetric fluid expansion device of  claim 16 , wherein:
 a. one of the first pair of rotors is mounted to a first rotor shaft and the other of the first pair of rotors is mounted to a second rotor shaft;   b. one of the second pair of rotors is mounted to a third rotor shaft and the other of the second pair of rotors is mounted to a fourth rotor shaft; and   c. one of the third pair of rotors is mounted to a fifth rotor shaft and the other of the third pair of rotors is mounted to a sixth rotor shaft;   d. wherein the power output device is rotated by the sixth rotor shaft.   
     
     
         20 . The multi-stage volumetric fluid expansion device of  claim 17 , wherein:
 a. the first rotor shaft is provided with a drive gear and the power output device is provided with an input gear that is driven by the drive gear;   b. the drive gear and input gear being configured in a step down arrangement such that the first, second, and third pairs of rotors rotate at a higher rotational speed than the power output device.   
     
     
         21 . The multi-stage volumetric fluid expansion device of  claim 20 , wherein:
 a. the power output device is provided with a clutch to selectively engage and disengage the first rotor shaft from the power output device.   
     
     
         22 . The multi-stage volumetric fluid expansion device of  claim 17 , wherein:
 a. the first rotor shaft is provided with a first drive gear and the third rotor shaft device is provided with an input gear that is driven by the drive gear;   b. the drive gear and input gear being configured in a step down arrangement such that the first, second, and third pairs of rotors rotate at a higher rotational speed than the power output device.   
     
     
         23 . The multi-stage volumetric fluid expansion device of  claim 20 , wherein:
 a. the power output device is provided with a clutch to selectively engage and disengage the first rotor shaft from the power output device.   
     
     
         24 . The multi-stage volumetric fluid expansion device of  claim 18 , wherein:
 a. the first shaft is provided with a first drive gear and the fourth shaft is provided with a first input gear that is driven by the first drive gear;   b. the first drive gear and first input gear being configured in a step up arrangement such that the first and second pair of rotors rotates at a lower rotational speed than the third pair of rotors.   
     
     
         25 . The multi-stage volumetric fluid expansion device of  claim 24 , wherein:
 a. the fourth shaft is provided with a second drive gear and the power output device is provided with a second input gear that is driven by the second drive gear;   b. the second drive gear and the second input gear being configured in a step down arrangement such that the third pair of rotors rotates at a higher rotational speed than the power output device.   
     
     
         26 . The multi-stage volumetric fluid expansion device of  claim 25 , wherein:
 a. the power output device is provided with a clutch to selectively engage and disengage the fourth rotor shaft from the power output device.   
     
     
         27 . The multi-stage volumetric fluid expansion device of  claim 19 , wherein:
 a. the first shaft is provided with a first drive gear and the third shaft is provided with a first input gear that is driven by the first drive gear;   b. the first drive gear and first input gear being configured in a step up arrangement such that the first pair of rotors rotates at a lower rotational speed than the second pair of rotors.   
     
     
         28 . The multi-stage volumetric fluid expansion device of  claim 27 , wherein:
 a. the fourth shaft is provided with a second drive gear and the sixth shaft is provided with a second input gear that is driven by the second drive gear;   b. the first drive gear and first input gear being configured in a step up arrangement such that the second pair of rotors rotates at a lower rotational speed than the third pair of rotors.   
     
     
         29 . The multi-stage volumetric fluid expansion device of  claim 28 , wherein:
 a. The sixth shaft is provided with a third drive gear and the power output device is provided with a third input gear that is driven by the third drive gear;   b. the third drive gear and the third input gear being configured in a step down arrangement such that the third pair of rotors rotates at a higher rotational speed than the power output device.   
     
     
         30 . The multi-stage volumetric fluid expansion device of  claim 29 , wherein:
 a. the power output device is provided with a clutch to selectively engage and disengage the sixth rotor shaft from the power output device.   
     
     
         31 . The multi-stage volumetric fluid expansion device of  claim 14 , wherein:
 a. the first pair of rotors have twisted non-contacting lobes, wherein one of the first pair of rotors has a number of twisted lobes that equals a number of twisted lobes of the other of the first pair of rotors;   b. the second pair of rotors have twisted non-contacting lobes, wherein one of the second pair of rotors has a number of twisted lobes that equals a number of twisted lobes of the other of the second pair of rotors; and   c. the third pair of rotors have twisted non-contacting lobes, wherein one of the third pair of rotors has a number of twisted lobes that equals a number of twisted lobes of the other of the third pair of rotors.   
     
     
         32 . A system for generating mechanical work via a closed-loop Rankine cycle, the system comprising:
 a. a power plant that produces a waste heat stream, wherein the power plant has a waste heat outlet through which the waste heat stream exits;   b. at least one heat exchanger in fluid communication with the waste heat stream, the heat exchanger being configured to heat a working fluid;   c. a multi-stage fluid expansion device configured to generate mechanical work at an output device from the working fluid, the expansion device having a housing within which a first stage and a second stage are disposed, the first stage being configured to expand the working fluid, the second stage being configured to receive the working fluid from the first stage and to expand the working fluid;   d. a condenser constructed and arranged to condense the working fluid;   e. a pump constructed and arranged to pump the condensed working fluid to the at least one heat exchanger.   
     
     
         33 . The system for generating mechanical work of  claim 32 , wherein:
 a. the multi-stage fluid expansion device housing further includes a third stage disposed within the housing that is configured to receive the working fluid from the second stage and to expand the working.   
     
     
         34 . The system for generating mechanical work of  claim 33 , further comprising:
 a. a second heat exchanger located between the first and second stages.   
     
     
         35 . The system for generating mechanical work of  claim 33 , wherein:
 a. The housing defines an internal working fluid pathway within which the working fluid can pass internally from the first stage to the second stage and from the second stage to the third stage.   
     
     
         36 . The system for generating mechanical work of  claim 35 , wherein:
 a. the output device is mechanically coupled to the third stage, the second stage is mechanically coupled to the third stage, and the first stage is mechanically coupled to the second stage such that power developed by each of the first, second, and third stages is transmitted to the power output device.   
     
     
         37 . The system for generating mechanical work of  claim 35 , further comprising:
 a. a first step up gear arrangement provided between the first and second stages such that a first pair of rotors associated with the first stage rotate at a lower speed than a second pair of rotors associated with the second stage; and   b. a second step up gear arrangement provided between the second and third stages such that the second pair of rotors rotate at a lower speed than a third pair of rotors associated with the third stage.   
     
     
         38 . The system for generating mechanical work of  claim 37 , further comprising:
 a. a step down gear arrangement provided between the third stage and the power output device such that third pair of rotors rotate at a lower speed than the power output device.   
     
     
         39 . The multi-stage volumetric fluid expansion device of  claim 38 , wherein:
 a. the power output device is provided with a clutch to selectively engage and disengage the third stage from the power output device.   
     
     
         40 . The multi-stage volumetric fluid expansion device of  claim 38 , wherein:
 a. the first pair of rotors have twisted non-contacting lobes, wherein one of the first pair of rotors has a number of twisted lobes that equals a number of twisted lobes of the other of the first pair of rotors;   b. the second pair of rotors have twisted non-contacting lobes, wherein one of the second pair of rotors has a number of twisted lobes that equals a number of twisted lobes of the other of the second pair of rotors; and   c. the third pair of rotors have twisted non-contacting lobes, wherein one of the third pair of rotors has a number of twisted lobes that equals a number of twisted lobes of the other of the third pair of rotors.   
     
     
         41 . A multi-stage volumetric fluid expansion device comprising:
 a. a first fluid expansion stage having a first pair of non-contacting rotors disposed between a first inlet and a first outlet, the first fluid expansion stage being configured to generate useful work at a first output shaft by expanding a working fluid from a first pressure to a second pressure that is lower than the first pressure;   b. a second fluid expansion stage having a second pair of non-contacting rotors disposed between a second inlet and a second outlet, the second fluid expansion stage being configured to generate useful work at a second output shaft by receiving the working fluid from the first fluid expansion stage outlet and expanding the working fluid to a third pressure that is lower than the second pressure; and   c. a power output device having an input gear that is rotated by the first and second output shafts.   
     
     
         42 . The multi-stage volumetric fluid expansion device of  claim 41  wherein:
 a. the first output shaft acts on the power output device input gear via a first gear train and the second output shaft acts on the power output device input gear via a second gear train in parallel to the first gear train. 
 
     
     
         43 . A multi-stage volumetric fluid expansion device comprising:
 a. a first fluid expansion stage having a first pair of non-contacting rotors disposed between a first inlet and a first outlet, the first fluid expansion stage being configured to generate useful work at a first output shaft by expanding a working fluid from a first pressure to a second pressure that is lower than the first pressure;   b. a second fluid expansion stage having a second pair of non-contacting rotors disposed between a second inlet and a second outlet, the second fluid expansion stage being configured to generate useful work at a second output shaft by receiving the working fluid from the first fluid expansion stage outlet and expanding the working fluid to a third pressure that is lower than the second pressure; and   c. a third fluid expansion stage having a third pair of non-contacting rotors disposed between a second inlet and a second outlet, the second fluid expansion stage being configured to generate useful work at a third output shaft by receiving the working fluid from the first fluid expansion stage outlet and expanding the working fluid to a third pressure that is lower than the second pressure;   d. wherein at least two of the first, second, and third output shafts are arranged in parallel to act on an input gear of the fluid expansion device.   
     
     
         44 . The multi-stage volumetric fluid expansion device of  claim 43  wherein:
 a. the input gear of the fluid expansion device is a power output device input gear; 
 b. the first output shaft acts on the power output device input gear via a first gear train; 
 c. the second output shaft acts on the power output device input gear via a second gear train; and 
 d. the third output shaft acts on the power output device input gear via a third gear train. 
 
     
     
         45 . The multi-stage volumetric fluid expansion device of  claim 43  wherein:
 a. the input gear of the fluid expansion device is a first stage input gear; 
 b. the first output shaft acts on a power output device input gear via a first gear train; 
 c. the second output shaft acts on the first stage input gear via a second gear train; and 
 d. the third output shaft acts on the first stage input gear via a third gear train. 
 
     
     
         46 . The multi-stage volumetric fluid expansion device of  claim 43  wherein:
 a. the input gear of the fluid expansion device is a power output device input gear; 
 b. the first output shaft acts on the power output device input gear via a first gear train; 
 c. the second output shaft acts on the power output device input gear via a second gear train; and 
 d. the third output shaft acts on a second stage input gear via a third gear train. 
 
     
     
         47 . The multi-stage volumetric fluid expansion device of  claim 46  wherein:
 a. the working fluid is directed through an internal passageway in a housing of the volumetric fluid expansion device from the second stage to the third stage. 
 
     
     
         48 . The multi-stage volumetric fluid expansion device of  claim 47  wherein:
 a. the second pair of rotors and the third pair of rotors are mounted to a common pair of shafts. 
 
     
     
         49 . The multi-stage volumetric fluid expansion device of  claim 43  wherein:
 a. the input gear of the fluid expansion device is a power output device input gear; 
 b. the first output shaft acts on the power output device input gear via a first gear train; 
 c. the second output shaft acts on a first stage input gear via a second gear train; and 
 d. the third output shaft acts on the power output device input gear via a third gear train. 
 
     
     
         50 . The multi-stage volumetric fluid expansion device of  claim 49  wherein:
 a. the working fluid is directed through an internal passageway in a housing of the volumetric fluid expansion device from the first stage to the second stage. 
 
     
     
         51 . The multi-stage volumetric fluid expansion device of  claim 50  wherein:
 a. the first pair of rotors and the second pair of rotors are mounted to a common pair of shafts.