Compressor having waste heat recovery with gas recycler

A compressor and waste heat recovery system is disclosed in which mechanical work from a prime mover along with work generated from the waste heat recovery system are used to operate the compressor. A gas producing system is heated by waste heat from operation of the compressor to produce a stream of gas used to drive a turbine. The turbine is in work communication with the compressor. In one embodiment the gas producing system is a metal hydride. An overrunning clutch can be used with the turbine. In one form multiple gas producing systems are used, one of which to emit gas while the other is used to receive and capture the emitted gas.

TECHNICAL FIELD

The present invention generally relates to fluid compressors having waste heat recovery, and more particularly, but not exclusively, to waste heat recovery using a gas recycler.

BACKGROUND

Providing fluid compressors capable of recovering waste heat remains an area of interest. Some existing systems have various shortcomings relative to certain applications. Accordingly, there remains a need for further contributions in this area of technology.

SUMMARY

One embodiment of the present invention is a unique compressor waste heat recovery system. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for recovering waste heat from a compressor. Further embodiments, forms, features, aspects, benefits, and advantages of the present application shall become apparent from the description and figures provided herewith.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

With reference toFIG. 1, one embodiment of a compressor and waste heat recovery system50is disclosed which includes a compressor52capable of being driven by a prime mover54such as for example an electric motor as well as an expander56(described further below) which operates on passage of a fluid produced as a result of a waste heat recovery process. The compressor52can be an air compressor, refrigerant compressor, air blower, or non-air gas compression system where waste heat exists. In one embodiment the compressor52is driven simultaneously through a mechanical coupling that combines power output from the prime mover54as well as power output from expander56created as a result of recovering waste heat.

As will be appreciated in the description herein, any type of compressor/compression system can be used in which a mechanical coupling of power output from the prime mover54and the expander56. For example, the compressor can be a multi-stage compressor. Alternatively and/or additionally, the compressor can be either an oil-flooded or oil-free compressor.

The expander56includes a mechanical device structured to produce mechanical shaft power and which moves upon interaction with a flowing fluid stream. To accomplish the conversion from fluid flow to shaft work, the expander56can take on the form of a turbine including, but not limited to, a reactive turbine and an impulse turbine, as well as a rotary screw expander, a scroll expander, a sliding vane expander, or similar device, among potential others. It will be appreciated that such a turbine can include any number of bladed features which interact with the moving fluid stream.

A mechanical coupling that integrates mechanical work from both the prime mover54and expander56can be achieved in many ways so that both can contribute to operation of the compressor52. For example, the mechanical coupling can include attachment to a double shafted motor to supplement input torque to the prime mover54; or it can be a direct attachment to the drive or driven gear between the prime mover54and compressor52; or directly to an opposing shaft (i.e. doubled shafted) of the compressor52; or to drive an alternate component within the compressor52such as a cooling fan, oil pump, or other rotating component independent of the prime mover54. A mechanical gear train can alternatively and/or additionally be used to reduce and/or increase the speed of any of the prime mover54, expander56, and compressor52when used with the coupling. Furthermore, to account for situations in which the expander56may not provide sufficient rotation/torque to the compressor52relative to the prime mover54, a clutch can be provided to permit the expander56to rotate freely so that the prime mover54is not required to also drive it along with the compressor52. Such a clutch can take on any form, for example a sprag roller, ratcheting, Bendix drive, or any other suitable type.

To set forth just one non-limiting example of the possible combinations above, the expander56can be attached to a gear train to reduce speed and increase torque, which can then be connected to a driven shaft of the compressor52via an overrunning clutch.

A gas producing system58is provided to produce the flow of fluid routed through the expander56which in turn is used to create mechanical work to assist in driving the compressor52. The gas producing system58includes a first gas system60and a second gas system62. The gas systems60and62are capable of acting as a gas source and/or a gas sink and can take on a variety of forms capable of acting as such. In one form the gas systems60and62are reversible in that one or both can act as a gas source in one mode of operation and act as a gas sink in another mode of operation.

The gas systems60and62can be a metal hydride system structured to absorb/adsorb hydrogen below an activation energy level (such as a temperature) and desorb hydrogen when above the activation energy level. For example, depending on the composition the metal hydride captures hydrogen at room temperature and moderate pressure, and releases the hydrogen at higher temperatures. The exact temperature and/or pressure of release depends upon the particular metal hydride composition. The process of onboarding hydrogen can require relatively low temperatures of the metal hydride to capture the hydrogen, and the process of desorbing can require higher temperatures of the metal hydride to emit the hydrogen. A metal hydride can include any number of potential compositions. As used herein, the term “hydride” also includes ionic hydride compositions as well as those that commonly use “hydride” in its name such as palladium hydride. The metal hydride can take on a variety of forms such as powder and pellet. In one non-limiting form the metal hydride can be a film or coating applied to the inside surface of the heat exchanger bed.

A valve actuation network is provided between the gas systems60and62and the mechanical expander56, and in the illustrated embodiment includes valves V1, V2, V3, and V4. The valves can be any type of device suitable for opening and closing fluid flow passageways. For example, the valves can be solenoids, electromechanical devices, electric actuators, hydraulic actuators, pneumatic actuators, etc. The fluid conduit network (which can be comprised of any suitable passageway materials/constructions) that connects the gas systems60and62with the mechanical expander56can be selectively reconfigured to provide fluid from the gas system60to the gas system62, or vice versa.

The illustrated embodiment depicts valves V1and V2in the open position, while valves V3and V4are closed, to permit fluid flow from the gas system60to the gas system62. To reverse the fluid flow direction, valves V1and V2can be closed while valves V3and V4are open. Such configurations in the illustrated embodiment permit fluid to traverse to the mechanical expander56via the same fluid intake conduit portion and exit the mechanical expander56from the same fluid outlet conduit portion.

One or more of the valves used in the embodiment depicted inFIG. 1, as well as valves depicted any other embodiment described herein, can be actuated via a controller structured to regulate system performance/operability/stability. The controller can be coupled with any suitable sensor to detect/measure/estimate any suitable information of the system50. The controller can be comprised of digital circuitry, analog circuitry, or a hybrid combination of both of these types. Also, the controller can be programmable, an integrated state machine, or a hybrid combination thereof. The controller can include one or more Arithmetic Logic Units (ALUs), Central Processing Units (CPUs), memories, limiters, conditioners, filters, format converters, or the like which are not shown to preserve clarity. In one form, the controller is of a programmable variety that executes algorithms and processes data in accordance with operating logic that is defined by programming instructions (such as software or firmware). Alternatively or additionally, operating logic for the controller can be at least partially defined by hardwired logic or other hardware.

Turning now toFIGS. 2 and 3, one embodiment is depicted of the expander56used to convert pressurized gas received from the gas producing system58to mechanical work provided to the compressor52. The embodiment depicted inFIGS. 2 and 3includes an electric motor64structured to provide motive power to the compressor52(only the housing of which is shown inFIG. 2for simplicity) via a shaft that projects through passage66(the shaft is also not shown for simplicity). The expander56is shown in exploded view inFIG. 3which depicts a flow inlet cover68, stator nozzles70, turbine wheel72, turbine wheel housing74, and speed reducing transmission76. The speed reducing transmission is coupled through an overrun clutch78to a pinion80. The pinion80contacts a drive gear82which in turn contacts a motor shaft driven gear84to provide work to a shaft coupled with the compressor52.

FIGS. 4 and 5depict an embodiment of the compressor and waste heat recovery system50in which the compressor52is an oil flooded screw compressor. Injection oil86is provided to the compressor50and together both produce a mixed stream of pressurized air and oil to a separator88. An oil flow from the separator88is used as the heat transfer fluid with the gas producing system58, and pressurized air from the separator88is routed first to a compressed air after cooler90, then to a compressed air dryer92, before being delivered to a user94of compressor air.

Valves V1-V10are depicted as either open or closed to illustrated the path through which the oil flow from the separator88traverses. InFIG. 4the oil flow is depicted as flowing to the gas system60before being routed to an oil cooler96and then to the gas system62before returning as injection oil86. Hydrogen flow in the gas producing system58flows from the gas system60, through the expander56, and then to the compressed air dryer before being received by the gas system62. It will be appreciated given the description herein that oil flow to gas system60heats the gas producing element to produce gas flow, and that the oil that flows to gas system62has been cooled so that the gas system62is likewise cooled to capture gas emitted from the gas system60.

FIG. 5depicts the reverse process in which oil from the separator88is used to heat gas system62so that hydrogen is released and thereafter received by gas system64, which itself is cooled by the oil after passing through devices to reduce its temperature including the gas system60as well as other heat exchangers.

Turning now toFIG. 6, an embodiment is depicted of the compressor and waste heat recovery system50in which the compressor52includes a first stage compressor98and a second stage compressor100. Air that is compressed by the stages98and100is used to provide heating to the gas producing system58. Compressed air from the first stage98is first routed to gas system60(to heat and release gas therefrom) before being routed to a compressed air inter cooler102, then to gas system62(to cool and thereby capture gas thereto) before being delivered to the second stage100. From the second stage100the compressed air is provided to a hydrogen reheater/compressed air precooler104before being routed to a compressed air after cooler106and thence to a user94. Gas flows between the gas systems60and62as will be appreciated given the general description above.

As will also be appreciated, when the reverse process is desired, the valve network can be reconfigured similar to the changes seen inFIGS. 4 and 5to permit a change in the heating/cooling combination of gas systems60and62as well as a change in the flow path between gas systems60and62.

One aspect of the present application provides an apparatus comprising a compressor system having a motor structured to provide work to a rotary compressor element that is structured to compress a fluid and thereby increase the pressure of the fluid at the same time that it produces heat, the compressor system including a heat rejecting component in thermal communication with the rotary compressor element; and a waste heat recovery system having a flowpath for the conveyance of a gas and a mechanical expander disposed in the flowpath to extract work from the conveyance of the gas and communicate the work to the rotary compressor element, the waste heat recovery system also having a chemical based gas storage device in thermal communication with the heat rejecting component of the compressor system, the chemical based gas storage device structured to desorb the gas at an activation energy level and capture the gas below the activation energy level through a sorption process, the gas being a different substance than a material of the chemical based gas storage device.

A feature of the present application provides wherein the chemical based gas storage device is a metal hydride.

Another feature of the present application provides wherein the metal hydride is in one of a powder form, pellet form, film form, or a coating form.

Yet another feature of the present application further includes a clutch disposed between the mechanical expander and the rotary compressor such that if insufficient rotative work is contributed by the mechanical expander the clutch is structured to permit free rotation of the rotary compressor element.

Still another feature of the present application provides wherein the rotary compressor element is a multiple stage compressor, and which further includes an intercooler heat exchanger disposed between a first stage of the multiple stage compressor and a second stage of the multiple stage compressor, the intercooler heat exchanger structured to cool a compressed air received from the first stage of the multiple stage compressor.

Yet still another feature of the present application provides wherein the rotary compressor element is an oil filled screw compressor, and which further includes an oil cooler structured to cool oil from the oil filled screw compressor.

Still yet another feature of the present application provides wherein the activation energy level is a temperature and which further includes an air/oil separator structured to receive an air/oil mixture from the rotary compressor element and convey separated air to a heat exchanger in thermal communication with the chemical based gas storage device.

A further feature of the present application includes another chemical based gas storage device disposed in flow path communication with the chemical based gas storage device such that the another chemical based gas storage device can capture the gas that is desorbed from the another chemical based gas storage device, and wherein the waste heat recovery system communicates mechanical work to the rotary compressor element.

A still further feature of the present application provides wherein the mechanical expander is a turbine.

Another aspect of the present application provides an apparatus comprising a compression system having a compressor driven by a prime mover and structured to increase a pressure and temperature of a working fluid, the compression system in thermal communication with a heat exchanger and structured to convey heat generated as a result of operation of the prime mover, and a supplemental work producing system structured to deliver work to the compressor which is supplemental to work provided by prime mover, the supplemental work producing system having a mechanical expander and a hydride gas recycler having a material composition that chemically initiates gas on-boarding below an activation energy level and gas emission above the activation level, wherein heat produced as a result of operation of the prime mover as it increases temperature of the working fluid is transferred through the heat exchanger to raise the temperature of the hydride gas recycler and thereby emit gas, the emitted gas routed through the mechanical expander to produce the supplemental work.

A feature of the present application provides wherein the prime mover is an electric motor, wherein the gas is hydrogen, and where the heat produced as a result of operation of the prime mover is in the form of an elevated temperature of the working fluid.

Another feature of the present application provides wherein the hydride gas recycler includes a first and second gas recycler in gaseous communication with one another via a flow path such that when the first gas recycler contributes gas via gas emission, the second gas recycler reclaims gas via on-boarding of gas, and where the mechanical expander is located in the flow path between the first gas recycler and the second gas recycler.

Yet another feature of the present application further includes a gear train in mechanical communication with the mechanical expander, wherein the gear train is structured to provide rotative output in an output direction when the gas flows through the mechanical expander from the first gas recycler to the second gas recycler, and wherein the gear train is structured to provide rotation output in the output direction when the gas flows through the mechanical expander from the second gas recycler to the first gas recycler.

Still another feature of the present application provides wherein the flow path includes an actuatable valve network that can be activated to reconfigure the flow path such that flow of gas through the mechanical expander occurs in the same direction irrespective of whether the first gas recycler or the second gas recycler is a gas emitter.

Yet still another feature of the present application further includes a clutch structured to discourage back driven behavior from the prime mover to the mechanical expander.

Still yet another feature of the present application provides wherein the compressor is a multi-stage compressor, and which further includes an intercooler between the stages.

A further feature of the present application provides wherein the compressor is an oil flooded compressor, and which further includes an air/oil separator, a oil/gas recycler heat exchanger that receives oil from the air/oil separator and exchanges heat with the first gas recycler, and an oil cooler positioned downstream of the oil/gas recycler.

Yet another aspect of the present application provides an apparatus comprising a compressor system having a motor structured to drive a compressor element, the compressor element configured to provide a compressed fluid when work from the motor is applied to it, and means for converting waste heat from the compressor system to mechanical work, the mechanical work added to the work provided from the motor to the compressor element.

Still yet another aspect of the present application provides a method comprising providing motor driven mechanical work to a compressor such that the compressor can produce a stream of compressed fluid, generating heat as a result of providing the mechanical power, heating a gas producing solid above an initiation temperature to produce a gas from the solid, routing the produced gas from the gas producing solid element to a mechanical expander to extract work from the mechanical expander, and mechanically summing the motor driven mechanical work with the work from the mechanical expander to complementarily drive the compressor.

A feature of the present application provides wherein the heating a gas producing solid includes transferring heat to a metal hydride material such that gas is produced in the form of hydrogen.

Another feature of the present application provides wherein the routing includes conveying the hydrogen to another gas producing solid element, which further includes operating a clutch during operation rotation of the mechanical expander, wherein the compressor is an oil flooded compressor, which further includes separating compressed air from oil and exchanging heat between the oil and the gas producing solid via a heat exchanger such that gas is produced as a result of the exchange of heat.

Yet another feature of the present application provides wherein the providing includes delivering work to a first compressor stage and a second compressor stage of the compressor element.

Yet still another feature of the present application further includes routing the stream of compressed fluid through a first heat exchanger in thermal communication with the gas producing solid, thence through an intercooler to provide cooling of the stream of compressed fluid, and thence through a second heat exchanger in thermal communication with another gas producing solid.

Still yet another feature of the present application further includes on-boarding the produced gas into the another gas producing solid.