Power generation by turbo expander generator based on specific output conditions

Abstract

The first turbo expander generator is configured to reduce a temperature or pressure of a process stream flowing through the first turbo expander generator by generating electrical power from the process stream. The second turbo expander generator is configured to reduce a temperature or pressure of a process stream flowing through the second turbo expander generator by generating electrical power from the process stream. The second turbo expander generator is downstream of the first turbo expander generator and receives a flow rate output from the first turbo expander generator. The first turbo expander generator and the second turbo expander generator each include the following features: An electric stator surrounds an electric rotor. An annulus defined by the electric rotor and the electric stator is configured to receive the process fluid stream. A magnetic bearing supports the rotor inside the stator. A housing surrounds the rotor and the stator. The housing is sealed between an inlet and an outlet of each turbo expander generator.

Description

[Technical field]

[0001] [CROSS REFERENCE TO RELATED APPLICATIONS] This application is a continuation-in-part of U.S. Patent Application No. 17 / 658,608, filed April 8, 2022, and claims priority to U.S. Patent Application No. 17 / 662,029, filed May 4, 2022, the contents of which are incorporated herein by reference.

[0002] This disclosure relates to power generation. [Background technology]

[0003] Natural gas is one of the primary sources of energy for many of our daily lives and activities. It is a fossil fuel that is attractive because of its abundance. Hydrogen is a rapidly expanding global energy storage market. Hydrogen is used in many manufacturing processes, from oil refining to food processing. Hydrogen is also used as a fuel source for gas turbines and in a wide range of fuel cells for power generation in the industrial and civilian transportation sectors.

[0004] To efficiently and effectively move such gas from production areas to consumption areas, a large and sophisticated transmission system is required. Natural gas transported through pipelines moves at high pressure within the pipeline. DISCLOSURE OF THEINVENTION

[0005] The present disclosure relates to generating electrical power with a turboexpander generator based on specific output requirements.

[0006] An exemplary embodiment of the subject matter described within this disclosure is a system having the following features: A first turbo expander generator configured to reduce a temperature or pressure of a process stream flowing through the first turbo expander generator by generating electrical power from the process stream. A second turbo expander generator configured to reduce a temperature or pressure of a process stream flowing through the second turbo expander generator by generating electrical power from the process stream. The second turbo expander generator is downstream of the first turbo expander generator and receives a flow output from the first turbo expander generator. The first turbo expander generator and the second turbo expander generator each include the following features: An electric stator surrounds an electric rotor. An annulus defined by the electric rotor and the electric stator is configured to receive a process fluid stream. A magnetic bearing supports the rotor inside the stator. A portion of the magnetic bearing is supported by the stator. A housing surrounds the rotor and the stator. A housing is sealed between the inlet and outlet of each turboexpander generator.

[0007] Aspects of the example system, which may be included in the example system alone or in combination with other aspects, include the following: The first turboexpander generator and the second turboexpander generator are substantially identical in critical dimensions and performance.

[0008] Aspects of the example system, which may be included alone or in combination with other aspects in an example system, include the following: A controller configured to regulate the first turboexpander generator and the second turboexpander generator.

[0009] Aspects of the example system that may be included in the example system alone or in combination with other aspects include the following: The inlet and outlet of each turboexpander are centered about the same longitudinal axis of each turboexpander generator.

[0010] Aspects of the example system that may be included in an example system alone or in combination with other aspects include the following: The stator includes a variable stator vane configured to throttle a fluid flow through the first turboexpander generator or the second turboexpander generator.

[0011] Aspects of the example system that may be included in the example system alone or in combination with other aspects include the following: a flow restriction valve upstream of the first turboexpander generator, the flow restriction valve configured to regulate flow through the first turboexpander generator and the second turboexpander generator.

[0012] Exemplary system aspects that may be included alone or in combination with other aspects in an exemplary system include the following: A Joule-Thomson valve defines a portion of a third conduit flow path disposed to carry a fluid flow in series with the first turboexpander generator and the second turboexpander generator.

[0013] An exemplary embodiment of the subject matter described within this disclosure is a method having the following features: A fluid stream is received by a first turboexpander generator defining a first portion of a conduit flow path. The fluid stream flows through an annulus defined by an electrical rotor and an electrical stator of the first turboexpander generator. The fluid stream is received from an outlet of the first turboexpander generator by a second turboexpander generator. The second turboexpander generator defines a second portion of the conduit flow path.

[0014] Aspects of the exemplary method that may be included in the exemplary method alone or in combination with other aspects include the following: The fluid stream comprises a hydrocarbon gas.

[0015] Aspects of the exemplary method, which may be included alone or in combination with other aspects in the exemplary method, include the following: The fluid stream comprises hydrogen gas.

[0016] Aspects of the exemplary method that may be included in the exemplary method alone or in combination with other aspects include the following: The fluid stream comprises air.

[0017] Aspects of the exemplary method that may be included in the exemplary method alone or in combination with other aspects include the following: The first turboexpander generator and the second turboexpander generator are substantially identical in performance and critical dimensions.

[0018] Aspects of the example method that may be included in the example method alone or in combination with other aspects include the following: Electrical power is generated by a first turboexpander generator.

[0019] Aspects of the example method that may be included in the example method alone or in combination with other aspects include the following: Electrical power generation is stopped by the first turboexpander generator in response to a change in certain downstream conditions.

[0020] Aspects of the example method that may be included in the example method alone or in combination with other aspects include the following: Producing electrical power with a first turboexpander generator includes regulating flow rate with a flow restriction valve based on certain downstream conditions.

[0021] Aspects of the example method that may be included in the example method alone or in combination with other aspects include the following: Electrical power generated by the first turboexpander generator or the second turboexpander generator is directed to an electrical user separate from users of the fluid flow.

[0022] An exemplary embodiment of the subject matter described within this disclosure is a system having the following features: The conduit includes a first turbo expander generator configured to reduce a temperature or pressure of a process stream flowing through the first turbo expander generator by generating electrical power from the process stream. The second turbo expander generator is configured to reduce a temperature or pressure of a process stream flowing through the second turbo expander generator by generating electrical power from the process stream. The second turbo expander generator is downstream of the first turbo expander generator and receives a flow output from the first turbo expander generator. The first turbo expander generator and the second turbo expander generator each include the following features: A stator surrounds the rotor. An annulus defined by the electric rotor and the electric stator is configured to receive the process fluid stream. A magnetic bearing supports the rotor inside the stator. A portion of the magnetic bearing is supported by the stator. A housing surrounds the rotor and the stator. A housing is sealed between the inlet and the outlet of each turboexpander generator. A Joule-Thomson valve is downstream or upstream of the first turboexpander generator or the second turboexpander generator. The Joule-Thomson valve is configured to receive the same flow rate as the first turboexpander generator and the second turboexpander generator. A controller is configured to regulate the first turboexpander generator and the second turboexpander generator.

[0023] Aspects of the example system that may be included in an example system alone or in combination with other aspects include the following: The stator includes a variable stator vane configured to throttle a fluid flow through the first turboexpander generator or the second turboexpander generator.

[0024] Aspects of the example system, which may be included in the example system alone or in combination with other aspects, include the following: The first turboexpander generator and the second turboexpander generator are substantially identical in critical dimensions and performance.

[0025] Aspects of the example system that may be included in the example system alone or in combination with other aspects include the following: a flow restriction valve upstream of the first turboexpander generator, the flow restriction valve configured to regulate flow through the first turboexpander generator, the second turboexpander generator, and a Joule-Thomson valve.

[0026] Aspects of the example system that may be included alone or in combination with other aspects in an example system include the following: A third turboexpander generator is included.

[0027] Embodiments of the example system that may be included in the example system alone or in combination with other embodiments include the following: a third turboexpander generator arranged to carry the same fluid flow as the first turboexpander generator, the second turboexpander generator, and the Joule-Thomson valve.

[0028] Aspects of the example system, which may be included alone or in combination with other aspects in an example system, include the following: The conduit is a first conduit. A third turboexpander generator is in a second conduit that is fluidly parallel with the first conduit.

[0029] Aspects of the example system that may be included in an example system alone or in combination with other aspects include the following: The controller is further configured to receive a data stream indicative of process conditions downstream of the first turboexpander generator and the second turboexpander generator, and to adjust, via the flow restriction valve, the flow rate based on one or more specified downstream conditions.

[0030] Aspects of the example system that may be included in an example system alone or in combination with other aspects include the following: The controller is further configured to condition electrical power generated by the first turboexpander generator and the second turboexpander generator and direct the electrical power to an electrical power grid, the electrical power being in phase with the electrical power grid.

[0031] The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will become apparent from the description and drawings, and from the claims. [Brief description of the drawings]

[0032] [Figure 1] 1 is a cross-sectional schematic diagram of a power generation system including a turboexpander generator connected to a power grid; [Diagram 2] FIG. 1 is a perspective view of an exemplary system arrangement including three turboexpander generators piped in parallel with each other. [Diagram 3] FIG. 1 is a schematic block diagram of an exemplary system arrangement including turboexpander generators piped in parallel with each other. [Figure 4] FIG. 2 is a block diagram of an example controller that may be used with aspects of the present disclosure. [Diagram 5] FIG. 1 is a perspective view of an exemplary system arrangement including two turboexpander generators plumbed in series with each other. [Figure 6] FIG. 1 is a schematic block diagram of an exemplary system arrangement including two turboexpander generators plumbed in series with each other. [Figure 7] 1 is a flowchart of an exemplary method that may be used in conjunction with aspects of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] Like reference numbers in the various drawings indicate like elements.

[0034] Natural gas, hydrogen, and other process gases are pressurized to facilitate efficient transportation in pipelines that can be many miles long. For example, pipelines transport gas from production sites (e.g., wells) to processing facilities, and from processing facilities to local distribution networks, such as regional, city, or district networks, or on-site industrial plant networks. To safely distribute and use the gas through the local distribution network, the process gas is reduced to a lower level (often using pressure regulators such as Joule-Thomson valves). The pressure is then reduced at pressure letdown (PLD) stations and distributed to industrial, commercial, and residential end users. PLD stations use control valves to achieve the required reduction, but generate a significant amount of waste energy in the process. Additional control valves may be used elsewhere for pressure control, such as in the pipeline between the production facility and the processing facility, in the processing facility sub-processes, and in the end user's processes and piping.

[0035] A turbo expander generator may be installed to recover waste energy from the pressure reduction and generate electrical power. The electrical power may be routed to a utility grid or elsewhere in the PLD station. In embodiments where the electrical power is routed to a utility grid, the utility grid may include the facility's local utility grid, a local independent utility grid, or a municipal utility grid. In some embodiments, the electrical power generated by the turbo expander generator is sold to a municipal utility. Similarly, a turbo expander generator may be installed at a gas storage facility upstream of one or more storage tanks to recover high pressure gas discharged from a tank truck through the turbo expander generator into the storage tank. Turbo expander generators are also relevant for other applications, such as hydrogen liquefaction processes, in which cooled and pressurized gaseous hydrogen is expanded to a liquid state. This expansion may be accomplished through the turbo expander generator, recovering waste energy from the expansion to generate electrical power. As discussed above, the electrical power may be routed to a utility grid or elsewhere, and may be used, for example, to power a compressor or other component of the liquefaction process. In each case, by recovering energy lost from the application of pressure reduction to natural gas and hydrogen, turboexpanders can generate electricity while reducing CO2 emissions, increasing overall plant efficiency, offsetting electricity costs and increasing revenue.

[0036] FIG. 1 is a cross-sectional schematic diagram of a power generation system 100 including a turbo expander generator 102 connected to a power grid 140. The power generation system 100 may be added to a PLD station to capture energy from gas expansion in a PLD process or for any other use as described above. The power generation system 100 includes a turbo expander generator 102 in parallel with a pressure control 130. The turbo expander generator 102 is axially arranged so that the turbo expander generator 102 can be mounted along a piping. In other words, the inlet 150 and the outlet 152 of the turbo expander generator 102 are centered on the same longitudinal axis (centerline 180) of the turbo expander generator 102. The turbo expander generator 102 functions as a generator by generating electrical energy from rotational kinetic energy obtained from the expansion of the process gas 120 through a turbine wheel 104. For example, the rotation of the turbine wheel 104 can be used to rotate a rotor 108 within a stator 110 to generate electrical power.

[0037] The turbo expander generator 102 includes a high-performance, high-speed permanent magnet generator that integrates a radial expansion turbine wheel 104 with low-loss active magnetic bearings (AMBs) 116a and 116b. The rotor assembly includes a permanent magnet section of the turbine wheel 104 that is mounted directly to the rotor hub. The rotor 108 is levitated by the magnetic bearing system, which provides a frictionless (or near-frictionless) interface between the dynamic and static components. The AMBs 116a and 116b facilitate lossless (or near-lossless) rotation of the rotor 108.

[0038] The turbo expander generator 102 is designed to allow the process gas 120 to flow through the system 100, which cools the generator and eliminates the need for auxiliary cooling devices. The turbo expander controller 118 for the turbo expander generator 102, in some embodiments, integrates a power converter 186 and a magnetic bearing controller (MBC) 212 in one cabinet. The power converter 186 allows for consistent and clean transport of generated power from the turbo expander generator 102 to the power grid 140. The power converter 186 adjusts the frequency and amplitude of the generated current to match the local power grid. In some embodiments, the power converter 186 functions as a power converter that converts the power generated by the turbo expander generator 102 to DC power and then generates an AC waveform of phase, frequency and voltage for synchronization and distribution to the power grid 140. After expansion, the process gas 120 exits the turbo expander generator 102 along the same axial path for downstream processes.

[0039] The turbo expander generator 102 includes a flow-through configuration. The flow-through configuration allows the process gas 120 to flow from an inlet side of the turbo expander generator 102 to an outlet side of the turbo expander generator 102. The process gas 120 enters the turbine wheel 104 through a radial gas inlet 154 and exits the turbine wheel 104 through an axial gas outlet 156. In some embodiments, the stator includes variable stator vanes 182 at the inlet 154. The variable stator vanes 182 are configured to throttle the fluid flow through the turbo expander generator 102 and may be used as an alternative or in addition to the flow control 126. The process gas 120 then flows through the generator and exits through the inlet 154, where the process gas 120 rejoins the gas pipeline 170. Typically, the process gas 120 is directed through the flow control system 126 to enter the turbo expander generator 102. The flow control system 126 includes flow or mass control valves and emergency shutoff valves. The flow control system 126 may be controlled by the turbo expander controller 118 or other electrical, mechanical or electromagnetic signals. For example, a fault condition may send a signal to the flow control system 126 to close or partially close, cutting off or restricting the gas supply to the turbo expander generator 102. Restricting or cutting off the gas flow to the turbo expander while maintaining a constant turbine wheel rotational speed reduces the power output from the turbo expander generator 102. In the example shown in FIG. 1, a signal channel 164 from the turbo expander controller 118 may be used to open or close the flow control system 126. In some embodiments, the turbo expander housing 112 is sealed between the inlet 150 and the outlet 152.

[0040] The process gas 120 is expanded by flowing through the turbine wheel 104, resulting in a reduction in the pressure of the process gas 120. The process gas 120 leaves the turbo expander generator 102 at a reduced pressure and / or temperature. The expansion of the process gas 120 through the turbine wheel 104 rotates the turbine wheel 104, which in turn rotates the rotor 108. The rotation of the rotor 108 within the stator 110 generates power. The turbo expander generator 102 achieves a certain reduction in pressure and extracts energy from the reduction in pressure to generate power. A pressure control valve 130, such as a conventional pressure regulator or a Joule-Thomson valve, may be installed in parallel (or in series) with the turbo expander generator 102. The pressure control valve 130 may be used to control the pressure of the process gas 120 flowing through the turbo expander generator 102. Excess high pressure process gas 120 not directed to the turbo expander generator 102 may be directed through the pressure control valve 130.

[0041] In some embodiments, the heater 122 may heat the process gas 120 before passing it to the turboexpander generator 102. For example, if the expansion of the process gas 120 through the turbine wheel 104 reduces the temperature of the process gas 120 to a point where moisture in the process gas 120 will freeze at the turbine wheel 104 or another downstream location, the process gas 120 may be heated in the heater 122 before entering the turboexpander generator 102. After heating, the process gas 120 may be directed into the turboexpander generator 102. Heating the process gas 120 may prevent moisture from freezing as the process gas 120 expands and reduces in temperature. In some embodiments, the process gas is heated in a heater after it exits the turboexpander 102.

[0042] The turboexpander generator 102 includes a turbine wheel 104. The turbine wheel 104 is shown as a radial turbine wheel, although other configurations, such as an axial turbine wheel, are within the scope of this disclosure. In this example, the process gas 120 is received from an inlet conduit 150 in the housing 112 and enters a radially oriented inlet 154 of the turbine wheel 104. In some embodiments, the process gas 120 flows through the inlet conduit 150 and is diverted by a flow diverter to the radial inlet 154, which directs the fluid to the radial inlet of the turbine wheel 104. After expansion, the process gas 120 exits the turbine wheel 104 through an axially oriented outlet 156 to an outlet conduit 152 in the housing 112.

[0043] In some embodiments, the turbine wheel 104 is directly fixed to the rotor 108 or an intermediate common shaft, for example, by fasteners, a rigid drive shaft, welding, or other methods. For example, the turbine wheel 104 is received at one end of the rotor 108 and held to the rotor 108 by a shaft. The shaft is threaded into the rotor 108 at one end and captures the turbine wheel 104 at the other end between one end of the rotor 108 and a nut threadably received on the shaft. In some embodiments, the turbine wheel 104 and the rotor 108 are coupled without a gearbox and rotate at the same speed. In some embodiments, the turbine wheel 104 is indirectly coupled to the rotor 108, for example, by a gear train, a clutch mechanism, or other methods.

[0044] The turbine wheel 104 includes a plurality of turbine wheel blades 106 that extend outwardly from a hub and interact with the expanding process gas 120 to rotate the turbine wheel 104. Figure 1 illustrates an unshrouded turbine wheel 104 in which each of the turbine blades 106 has an exposed, generally radially oriented blade tip that extends between a radial inlet 154 and an axial outlet 156. As described in more detail below, the blade tips are substantially sealed against a shroud 114 inside a housing 112. In certain cases, the turbine wheel 104 is a shrouded turbine wheel.

[0045] In a configuration with an unshrouded turbine wheel 104, the housing 112 includes an inwardly facing shroud 114 that is in close proximity to the turbine wheel blades 106 and does not contact the turbine wheel blades 106 during most of the operation. The close proximity of the turbine wheel blades 106 and the shroud 114 substantially blocks the passage of the process gas 120 between the turbine wheel blades 106 and the shroud 114 as the process gas 120 flows through the turbine wheel 104. Although some amount of the process gas 120 may leak or pass between the turbine wheel blades 106 and the shroud 114, this leakage is insignificant during operation of the turbine wheel 104. In certain cases, this leakage may be in accordance with other similar unshrouded turbine / shroud surface interfaces using conventional tolerances between the turbine wheel blades 106 and the shroud 114. The amount of acceptable leakage may be predetermined. The operating parameters of the turbine generator may be optimized to reduce leakage. In some embodiments, the housing 112 is sealed to prevent the process gas 120 from leaking out of the radial inlet 154 of the turbine wheel 104 .

[0046] The shroud 114 may be a particular distance away from the turbine wheel blades 106 and is maintained at that distance during operation of the turboexpander generator 102 using a magnetic positioning device including active magnetic bearings and position sensors.

[0047] The bearings 116a and 116b are positioned to rotatably support and carry the rotor 108 and turbine wheel 104 relative to the stator 110 and shroud 114. In some embodiments, the turbine wheel 104 is supported in a cantilevered (overhung) manner by the bearings 116a and 116b. In some embodiments, the turbine wheel 104 is supported in a non-cantilevered manner, and the bearings 116a and 116b may be located on the outlet side of the turbine wheel 104, for example, in an inter-bearing arrangement. In some embodiments, one or more of the bearings 116a or 116b include a ball bearing, a needle bearing, a magnetic bearing, a foil bearing, a journal bearing, or the like.

[0048] Bearings 116a and 116b may be combination radial and thrust bearings and may provide radial and axial support for rotor 108. Other configurations are also possible. Bearings 116a and 116b do not have to be the same type of bearing.

[0049] In embodiments where the bearings 116a and 116b are magnetic bearings, a magnetic bearing controller (MBC) 212 is used to control the magnetic bearings 116a and 116b. The position sensors 117a, 117b may be used to detect the position or change in position of the turbine wheel 104 and / or rotor 108 relative to the housing 112 or other reference point (such as a predetermined value). The position sensors 117a, 117b may detect axial and / or radial displacement. The magnetic bearings 116a and / or 116b may respond to information from the position sensors 117a, 117b and adjust the detected displacement as needed. The MBC 212 may receive information from the position sensors 117a, 117b and process the information to provide control signals to the magnetic bearings 116a, 116b. The MBC 212 may communicate with various components of the turboexpander generator 102 via the communication channel 162.

[0050] The use of the magnetic bearings 116a, 116b and position sensors 117a, 117b to maintain and / or adjust the position of the turbine wheel blades 106 so that they remain in proximity to the shroud 114 allows the turbo expander generator 102 to operate without the need for bearing seals (e.g., without the need for dynamic seals). The use of active magnetic bearings 116a, 116b in the turbo expander generator 102 eliminates physical contact between rotating and stationary components and reduces or eliminates the need for lubrication, lubrication systems, and seals.

[0051] In some embodiments, the turboexpander generator 102 includes one or more backup bearings. For example, during start-up and shut-down or power outages that affect the operation of the magnetic bearings 116a and 116b, the bearings may be used to rotatably support the turbine wheel 104 during those periods. The backup bearings may include ball bearings, needle roller bearings, journal bearings, etc.

[0052] As previously mentioned, the turbo expander generator 102 is configured to generate electrical power in response to the rotation of the rotor 108. In certain cases, the rotor 108 may include one or more permanent magnets. The stator 110 includes a plurality of conductive coils. Electrical power is generated by the rotation of the magnets within the coils of the stator 110. The rotor 108 and the stator 110 may be configured as a synchronous permanent magnet polyphase alternating current (AC) generator. The electrical output 160 may be, for example, a three-phase output. In certain cases, the stator 110 may include a plurality of coils (e.g., three or six coils for a three-phase AC output). As the rotor 108 rotates, a voltage is induced in the stator 110. In either example, the magnitude of the voltage induced in the stator coil is proportional to the rate at which the magnetic field surrounding the coil changes over time (i.e., the rate at which the magnetic field passes on both sides of the coil). When the rotor 108 is coupled to rotate at the same speed as the turbine wheel 104, the turbo expander generator 102 is configured to generate power at that speed. Such a turbo expander generator 102 is referred to as a "high speed" turbine generator. For example, the turbo expander generator 102 can generate up to 135 kW of power at a continuous rotational speed of 30,000 rpm. In some embodiments, the turbo expander generates power in the order of 315 kW at higher rotational speeds (e.g., in the order of 23,000 rpm).

[0053] In some embodiments, the design of the turbine wheel 104 is based on the particular parameters of the output gas from the turboexpander generator 102. For example, the rotor and stator design may be based on the particular temperature of the process gas 120 exiting the turboexpander generator 102. In some embodiments, the turboexpander generator is constructed with a single size with interchangeable turbine wheels 400 that can be changed for specific power outputs and processes.

[0054] The turbo expander generator 102 is coupled to a turbo expander controller 118. The turbo expander controller 118 may include various components, such as, for example, a power converter 186 and / or a magnetic bearing controller (MBC) 212 (discussed above). The power converter 186 may be, for example, a variable speed drive (VSD) or a variable frequency drive.

[0055] The electrical output 160 of the turbo expander generator 102 is connected to a power converter 186, which may be programmed for specific power requirements. In some embodiments, the power converter 186 may include an insulated-gate bipolar transistor (IGBT) rectifier 188 that converts the variable frequency high voltage output from the turbo expander generator 102 to direct current (DC). In some embodiments, the rectifier 188 is a three-phase rectifier for a three-phase AC input current. An inverter 210 converts the DC from the rectifier 188 to AC for supply to the power grid 140. In certain embodiments, the inverter 210 converts the DC to 380 VAC to 480 VAC at 50-60 Hz for supply to the power grid 140. The specific output of the power converter 186 depends on the power grid 140 and the application. Other conversion values ​​are within the scope of this disclosure. The power converter 186 matches its output to the power grid 140 by sampling the voltage and frequency of the power grid and varying the output voltage, phase and frequency of the inverter 210 to match, or synchronize, with the sampled power grid voltage, phase and frequency.

[0056] In some embodiments, the power converter 186 is a bi-directional power converter. In such an embodiment, the rectifier 188 can receive AC current from the power grid 140 and convert the AC current to DC current. The inverter 210 can convert the DC from the rectifier 188 to AC and provide it to the generator. In such an embodiment, power can be provided from the power grid 140 to the generator to drive rotation of the rotor 108, which in turn drives the turbine wheel 104 to induce the flow of process gas. In summary, in an embodiment where the power converter 186 is a bi-directional power converter, the flow of power can be reversed and used by the generator to induce the flow of process gas (as opposed to the process gas contributing expansion work to generate power).

[0057] The turbo expander generator 102 is also connected to the MBC 212 in the turbo expander controller 118. The MBC 212 constantly monitors position, current, temperature and other parameters to control the turbo expander generator 102 and the active magnetic bearings 116a, 116b. For example, the MBC 212 is coupled to position sensors 117a, 117b to monitor the radial and axial positions of the turbine wheel 104 and rotor 108. The MBC 212 can control the magnetic bearings 116a, 116b to selectively vary the stiffness and damping characteristics of the magnetic bearings 116a, 116b as a function of spin speed. The MBC 212 can further control synchronism cancellation, which includes auto-balancing control, adaptive vibration control, adaptive vibration rejection control, and unbalanced force rejection control.

[0058] FIG. 2 is a perspective view of an exemplary system 200 including two turbo expander generators 102 plumbed in parallel with one another. That is, a fluid flow can pass through the first turbo expander generator 102a or the second turbo expander generator 102b, but not through both. In some embodiments, such an arrangement is used in situations where there is a high flow rate requirement and a low pressure drop requirement. The aforementioned turbo expander 102 can be any of the turbo expander generators described throughout this disclosure. The system 200 includes a first turbo expander generator 102a that defines a portion of a first conduit flow path 202a. The first turbo expander generator is configured to reduce the temperature or pressure of a process stream passing through the first turbo expander generator 102a by generating electrical power from the process stream. That is, the turbo expander generator converts mechanical energy present in the fluid stream into electrical energy and converts a specific amount of energy to generate a specified fluid condition for a downstream user 204. In some embodiments, the downstream user includes a pipeline. In general, the first turboexpander generator 102 a and the second turboexpander generator 102 b are configured to regulate (fully or partially) a pressure or temperature specified for a downstream user 204 .

[0059] The second turbo expander generator 102b defines a portion of the second conduit flow path 202b. The first and second conduit flow paths 202a and 202b (and the first and second turbo expander generators 102a and 102b are arranged to carry fluid flow in parallel with each other). The second turbo expander generator is identical to or substantially similar to the first turbo expander generator 102a, except for differences described herein (e.g., in topology, performance characteristics and / or critical dimensions, (e.g., in one or more of power output, electrical stator dimensions and / or electromagnetic properties, rotor magnetic properties and / or dimensions, turbine wheel aerodynamic properties and / or dimensions, turbo expander performance, housing aerodynamic properties and / or internal dimensions, overall length, etc.). To the extent that the second turbo expander generator 102b is substantially similar, but not identical, to the first turbo expander generator 1021, the differences in performance and dimensions may, in certain cases, be within 10% of the performance and dimensions of the first turbo expander generator 102a.

[0060] In some embodiments, additional parallel flow paths 202 are included in the system 200. For example, in some embodiments, a Joule-Thomson valve 206 defines a portion of a third conduit flow path 202d. The third conduit flow path 202d is arranged to flow or convey fluid in parallel with the first conduit flow path 202a and the second conduit flow path 202b.

[0061] In some embodiments, the system 200 may include more or fewer turbo expander generators. For example, in some embodiments, the third turbo expander generator 102c defines a portion of a fourth conduit flow path 202c that is arranged to carry a fluid flow in parallel with the first conduit flow path 202a, the second conduit flow path 202b, and the third conduit flow path 202d. Although specific examples and arrangements are described throughout this disclosure, any number of turbo expander generators 102 and Joule-Thomson valves 206 may be arranged in parallel with one another without departing from this disclosure.

[0062] Regardless of the number of turbo expander generators used, all or some of the turbo expander generators include a restrictor valve 208 in some embodiments. The restrictor valve 208 regulates the flow rate through either turbo expander generator 102 in series with the restrictor valve. The restrictor valve 208 may be included upstream or downstream of the turbo expander generator 102 that is regulated by the restrictor valve. For example, a first restrictor valve 208a is upstream of the first turbo expander generator 102a and regulates (fully or partially) the flow rate through the first turbo expander generator 102a. Alternatively or additionally, in some embodiments, a second restrictor valve 202b is upstream of the second turbo expander generator 102b. The second restrictor valve 208b regulates the flow rate through the second turbo expander generator 102b.

[0063] FIG. 3 is a schematic block diagram of an exemplary system 300 arrangement including two turbo expander generators (102a, 102b) piped in parallel with each other. The system includes a controller 118. The controller 118 is coupled to various components in the system 300, such as the turbo expander generator 102, the flow restriction valve 208, various sensors 302, and the power system 140. During operation, the controller is configured to receive a data stream indicative of process conditions downstream of the first turbo expander generator 102a and the second turbo expander generator 102b. The controller 118 is configured to regulate the first turbo expander generator 102a and the second turbo expander generator 102b. For example, in some cases, the controller 118 adjusts the flow rate through the flow restriction valve 208 based on one or more specific or required downstream conditions. In some cases, the controller 118 adjusts the electrical load of one or more turbo expander generators 102 based on one or more specific or required downstream conditions.

[0064] In some embodiments, the controller is configured to regulate the electrical power generated by the first turbo expander generator 102a and the second turbo expander generator 102b. For example, in some embodiments, the controller regulates the voltage, current, or phase of the electricity generated by the turbo expander generators 102. By making such regulation, the controller can direct in-phase electrical power to the power grid.

[0065] FIG. 4 is a block diagram of an example controller 118 that may be used within the context of the present disclosure. The controller 118 may, among other things, monitor parameters of the system and send signals to actuate and / or adjust various operating parameters of the system. As shown in FIG. 4, the controller 118, in certain cases, includes a processor 450 (e.g., implemented as a processor or processors) and a memory 452 (e.g., implemented as a memory or memories) that includes instructions that cause the processor 450 to perform the operations described herein. The processor 450 is coupled to an input / output (I / O) interface 454 for sending and receiving communications to components in the system, including, for example, the sensors 302. In certain cases, the controller 118 may further communicate status and send actuation and / or control signals to one or more of the various system components of the system 100, including the flow restriction valve 208, as well as other sensors 302 (e.g., pressure sensors, temperature sensors, vibration sensors, and other types of sensors) that may be provided in any of the systems described herein. In certain cases, the controller 118 may communicate status and send actuation and control signals to one or more components in the system, such as the restrictor valve 208. The communication may be wired, wireless, or a combination of wired and wireless. In some embodiments, controllers similar to the controller 118 may be located in other locations, such as in a data van, elsewhere on-site, or off-site. In some embodiments, the controller 118 may be a distributed controller with different portions located around the site or off-site. For example, in certain cases, the controller 118 may be located in the turbo expander generator 102 or in another control room or data van. Additional controllers may be used throughout the site as standalone controllers or networked controllers without departing from this disclosure.

[0066] The controller 118 may operate to monitor, command, and use the turbo expander generator 102 to regulate process conditions and generate electricity for downstream users 204. To monitor and control the vortex turbo expander generator 102, the controller 118 is used in combination with various sensors, both in the turbo expander generator and the downstream users. Input and output signals, including data from the sensors controlled and monitored by the controller 118, may be continuously recorded by the controller 118.

[0067] The controller 118 may have various levels of autonomy to control the turbo expander generator 102. For example, the controller 118 may begin to sense a change in process conditions of downstream users 204 and an operator adjusts the restrictor valve 208 or the electrical load of the turbo expander generator 102. Alternatively, the controller 118 may begin to sense a change in process conditions of downstream users 204 and an operator may adjust the restrictor valve 208 or the electrical load of the turbo expander generator 102 without other input from the operator. Alternatively, the controller 118 may begin to sense a change in process conditions of downstream users 204 and an operator may adjust the restrictor valve 208 or the electrical load of the turbo expander generator 102 without other input from the operator.

[0068] FIG. 5 is a perspective view of an exemplary system 500 arrangement including two turbo expander generators 102 piped in series with each other. That is, fluid flows through the first turbo expander generator 102d and then through the second turbo expander 102e. During normal operation, the fluid flow always passes through both the first turbo expander generator 102d and the second turbo expander 102e sequentially. In some embodiments, such an arrangement is used in situations where a high pressure drop requirement exists. The system 500 is substantially similar to the systems 500 and 500 previously described, except for the differences described herein or illustrated in the associated figures. In some embodiments, the first turbo expander generator 102d and the second turbo expander generator 102e have substantially similar critical dimensions and performance metrics. In some embodiments, the first turbo expander generator 102d and the second turbo expander generator 102e have different critical dimensions and performance metrics. The first turbo expander generator 102d defines a first portion of the conduit flow path 502a, and the second turbo expander generator 102e defines a second portion of the conduit flow path 502a. The first and second portions of the conduit flow path 502a are arranged to convey fluid flow in series with one another. The users 204 are downstream of the first turbo expander generator 102d and the second turbo expander generator 102e. The first turbo expander generator 102d and the second turbo expander generator 102e are configured to regulate (fully or partially) a specified pressure or temperature for the downstream users 204. It should be noted that the first turbo expander generator 102d and the second turbo expander generator 102e share the same flow restriction valve 208c due to the equal mass flow rates between them.

[0069] 6 is a schematic block diagram of an exemplary system 600 arrangement including two turbo expander generators 102d and 102e plumbed in series with one another. In some embodiments, a Joule-Thomson valve 206 defines a third portion of the conduit flow path 502a. A controller is configured to regulate the first turbo expander generator 102d and the second turbo expander generator 102e. The controller 118 is substantially similar to the controller 118 described above.

[0070] 7 is a flow chart of an exemplary method 700 that may be used with aspects of the disclosure. At 702, a first fluid stream is received in a first turbo expander generator. At 704, a second fluid stream is received in a second turbo expander generator. In some embodiments, the first turbo expander generator and the second turbo expander generator define first and second portions of a conduit flow path. That is, the first and second portions of the conduit flow path are arranged to carry the fluid streams in series. In some embodiments, the first turbo expander generator and the second turbo expander generator are plumbed to first and second conduit flow paths, respectively, that are arranged to carry the fluid streams in parallel with each other.

[0071] In some embodiments, the first and second fluid streams comprise a hydrocarbon gas. In some embodiments, the first and second fluid streams comprise hydrogen gas. In some embodiments, the first and second fluid streams comprise carbon dioxide gas. In some embodiments, the first and second fluid streams comprise air. Any high pressure gas that requires pressure reduction, such as gas from a pipeline entering a processing facility, can be pressure reduced or cooled by the turboexpander generators and arrangements described throughout this disclosure.

[0072] Electrical power is generated by at least one of the turbo expander generators. For example, in some embodiments, the electrical power is generated by a first generator. In some embodiments, the electrical power is generated by a second turbo expander generator. In some cases, generating electrical power by either turbo expander generator includes adjusting the flow rate through the turbo expander generator 102, for example, by the flow restrictor valve 208, based on certain downstream conditions. In some cases, generating electrical power includes adjusting the electrical load of the turbo expander generator, for example, by the turbo expander generator controller 118, based on certain downstream conditions. In some cases, generating electrical power by either turbo expander generator may be stopped in response to a change in certain downstream conditions. For example, generation is stopped when the supply of droplets falls below a certain threshold. When electrical power is being generated, in some embodiments, the generated electrical power is directed to electrical consumers other than downstream users 204 of the first and second fluid streams.

[0073] Although several exemplary embodiments have been described in which turbo expander generators 102 are arranged in parallel or in series with other turbo expander generators 102 or Joule-Thomson valves 206, other arrangements are possible without departing from this disclosure, such as adding an additional turbo expander generator in parallel with a turbo expander generator(s) already arranged in series. Alternatively or additionally, a turbo expander generator 102 may be added in series with a turbo expander 102 already arranged in parallel with another expander. In some embodiments, an additional pressure regulator, such as a Joule-Thomson valve 206 (or other regulator), may be added in parallel or in series with any turbo expander generator.

[0074] Although several embodiments have been described, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. Accordingly, other embodiments are within the scope of the following claims.

Claims

1. a first turboexpander generator including a first turbine wheel configured to generate rotational motion from a process stream to reduce a temperature or pressure of the process stream flowing through the first turboexpander generator; a second turboexpander generator including a second turbine wheel configured to generate rotational motion from a process stream to reduce a temperature or pressure of the process stream flowing through a second turboexpander generator, the second turboexpander generator being downstream from the first turboexpander generator and receiving a flow output from the first turboexpander generator, the first turboexpander generator and the second turboexpander generator each comprising: an electric rotor coupled to each of said turbine wheels for rotation therewith; an electric stator surrounding the electric rotor, the annulus defined by the electric rotor and the electric stator being configured to receive a process fluid flow; a magnetic bearing that carries the electric rotor within the electric stator and is supported in part by the electric stator; a housing enclosing said electrical rotor and said electrical stator, said housing being sealed between the inlet and outlet of each turboexpander generator; Including, a second turboexpander generator, the outlet of the first turboexpander generator being fluidly coupled to the inlet of the second turboexpander generator such that all flow exiting the outlet of the first turboexpander generator is directed to the inlet of the second turboexpander generator; A system including:

2. The system of claim 1 , wherein the first turboexpander generator and the second turboexpander generator are substantially identical in critical dimensions and performance.

3. The system of claim 1 , further comprising a controller configured to regulate the first turboexpander generator and the second turboexpander generator.

4. The system of claim 3 , wherein the inlet and the outlet of each turboexpander are centered about the same longitudinal axis of each turboexpander generator.

5. The system of claim 3 , wherein the electrical stator includes variable stator vanes configured to throttle a fluid flow through the first turboexpander generator or the second turboexpander generator.

6. 2. The system of claim 1, further comprising a flow restriction valve upstream of the first turboexpander generator, the flow restriction valve configured to regulate flow through the first turboexpander generator and the second turboexpander generator.

7. 10. The system of claim 1, further comprising a Joule-Thomson valve defining a portion of a third conduit flow path disposed to convey a fluid flow in series with the first turboexpander generator and the second turboexpander generator.

8. receiving a fluid stream by a first turboexpander generator defining a first portion of a conduit flowpath, the fluid stream flowing through an annulus defined by an electrical rotor and an electrical stator of the first turboexpander generator; receiving an entirety of the fluid flow from the outlet of the first turboexpander generator by a second turboexpander generator, the second turboexpander generator defining a second portion of the conduit flowpath; The method includes:

9. The method of claim 8 , wherein the fluid stream comprises a hydrocarbon gas.

10. The method of claim 8 , wherein the fluid stream comprises hydrogen gas.

11. The method of claim 8 , wherein the fluid flow comprises air.

12. 9. The method of claim 8, wherein the first turboexpander generator and the second turboexpander generator are substantially identical in performance and critical dimensions.

13. The method of claim 8 further comprising generating electrical power with the first turboexpander generator.

14. 10. The method of claim 8, further comprising ceasing to generate electrical power by the first turboexpander generator in response to a change in a particular downstream condition.

15. 10. The method of claim 8, wherein generating electrical power with the first turboexpander generator includes regulating flow with a flow restriction valve based on particular downstream conditions.

16. 9. The method of claim 8, further comprising directing electrical power generated by the first turboexpander generator or the second turboexpander generator to an electrical user separate from a user of the fluid stream.

17. a first turboexpander generator including a first turbine wheel configured to generate rotational motion from a process stream to reduce a temperature or pressure of the process stream flowing through the first turboexpander generator; a second turboexpander generator including a second turbine wheel configured to generate rotational motion from the process stream to reduce a temperature or pressure of the process stream flowing through a second turboexpander generator, the second turboexpander generator being downstream of the first turboexpander generator and receiving a total flow output from the first turboexpander generator, the first turboexpander generator and the second turboexpander generator each comprising: an electric rotor coupled to each of said turbine wheels for rotation therewith; an electric stator surrounding the electric rotor, the annulus defined by the electric rotor and the electric stator being configured to receive a process fluid flow; a magnetic bearing that carries the electric rotor within the electric stator and is supported in part by the electric stator; a housing enclosing the electrical rotor and the electrical stator, the housing being sealed between the inlet and outlet of each turboexpander generator; a second turboexpander generator including: a Joule-Thomson valve located downstream or upstream of the first turboexpander generator or the second turboexpander generator, the Joule-Thomson valve configured to receive the same flow rate of the process stream as the first turboexpander generator and the second turboexpander generator; a conduit comprising: a controller configured to regulate the first turboexpander generator and the second turboexpander generator; A system including:

18. The system of claim 17 , wherein the electrical stator includes variable stator vanes configured to throttle a fluid flow through the first turboexpander generator or the second turboexpander generator.

19. 20. The system of claim 17, wherein the first turboexpander generator and the second turboexpander generator are substantially identical in critical dimensions and performance.

20. 20. The system of claim 19, further comprising a flow restriction valve upstream of the first turboexpander generator, the flow restriction valve configured to regulate flow through the first turboexpander generator, the second turboexpander generator, and a Joule-Thomson valve.

21. The system of claim 19 further comprising a third turboexpander generator.

22. 22. The system of claim 21, wherein the third turboexpander generator is arranged to carry the same fluid flow as the first turboexpander generator, the second turboexpander generator and the Joule-Thomson valve.

23. 22. The system of claim 21, wherein the conduit is a first conduit and the third turboexpander generator is in a second conduit in fluid parallel with the first conduit.

24. The controller: receiving a data stream indicative of process conditions downstream of the first turboexpander generator and the second turboexpander generator; The restrictor valve regulates the flow rate based on one or more specified downstream conditions.

20. The system of claim 19, further configured to:

25. The controller: Regulating the electrical power generated by the first turboexpander generator and the second turboexpander generator; Directing power to a power grid where the power is in phase 20. The system of claim 19, further configured to:

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