Systems and methods for producing and supplying dense liquid oxygen products

Abstract

Systems and methods are provided for liquefying and densifying oxygen for use in space vehicle application scenarios using high pressure air or synthetic air as a refrigerant source. The disclosed systems and methods employ a heat exchanger arrangement including a first heat exchange device configured to liquefy at least a portion of a high pressure gaseous oxygen stream and a high pressure gaseous air stream via indirect heat exchange with a refrigerant stream to produce a liquid oxygen stream and a liquid air stream. The heat exchanger arrangement further includes a second heat exchange device configured to densify the liquid oxygen stream via indirect heat exchange with the liquid air stream, which produces a densified liquid oxygen and a cold boil-off air stream. The refrigerant stream includes a mixture of exhaust streams from one or more turbines and the cold boil-off air stream.

Description

Technical Field

[0001] This invention relates to a system and method for preparing and supplying dense liquid oxygen products for use in spacecraft applications, and more specifically, to a system and method for preparing dense liquid oxygen streams from high-pressure gaseous oxygen streams using high-pressure air or synthetic air as a refrigerant at space launch facilities. Background Technology

[0002] Spacecraft launch applications require large quantities of liquid fuel and liquid oxygen to generate the propulsion needed to propel the spacecraft into space. The amount of liquid oxygen is extremely large, typically exceeding 1000 mtpd, and it must be densified through deep supercooling to maximize the oxidizer payload at launch. Supercooling liquid oxygen below its boiling point produces a denser oxidizer, thus requiring a smaller tank to hold the same amount. The limitation on densification levels is solidification at the material's triple point. Minimizing the volume and weight of the fuel / oxygen tank is crucial for rocket design feasibility, and it is desirable to pack all the necessary fuel / oxygen into the smallest possible volume.

[0003] The challenges facing the aerospace industry related to oxygen densification include reducing operating costs, including electricity costs, and reducing the capital costs of oxygen densification. Depending on the size of the spacecraft, supplying liquid oxygen to the launch platform at the launch facility typically requires transporting more than 40 liquid oxygen trailers by truck to the launch facility, where the liquid oxygen is then densified. Using so many liquid trailers to transport liquid oxygen is problematic from both a logistical and safety perspective. Most current oxidizer densification processes at spacecraft launch facilities typically require more liquid nitrogen trailers than liquid oxygen trailers to be brought in from external sources for the densification of the liquid oxygen. This further increases the overall logistical burden of transporting large quantities of liquid nitrogen or other cryogenic liquids by truck to the launch facility.

[0004] To further improve launch operations and reduce operating costs, it is clearly necessary to reduce or eliminate the truck transport of liquid oxygen and liquid nitrogen to the launch facility. Furthermore, there remains a need to develop improved refrigeration cycles for the liquefaction and densification of oxygen at the launch facility. These improved refrigeration cycles should both enhance the densification of liquid oxygen, used as an oxidizer in spacecraft launch applications, and reduce the electricity costs associated with such liquefaction and densification, ideally to a level where the electricity consumed in oxygen liquefaction and densification is negligible. Current liquefaction and densification processes performed at spacecraft launch facilities may require power delivery typically exceeding 30 MW, which, depending on the launch site's location and configuration, may be impractical.

[0005] Examples of conventional liquid oxygen densification systems are shown and described in U.S. Patent Nos. 10,808,967 and 11,293,671. These and many other processes have been developed that utilize liquid nitrogen and / or rare gases to produce liquid oxygen via indirect heat exchange. See, for example, U.S. Patent Application Publication No. 2023 / 068126, which discloses a process in which liquid nitrogen is vaporized and turbine-expanded to absorb the energy required to convert gaseous oxygen into liquid oxygen. Alternatively, as disclosed in U.S. Patent Application Publication No. 2022 / 099364, the use of high-pressure gaseous nitrogen for oxygen liquefaction and densification in spacecraft launch applications on offshore platforms has been proposed. Summary of the Invention

[0006] This invention can be characterized as a system for preparing a dense liquid oxygen stream from a high-pressure gaseous oxygen stream, the system comprising: (i) a heat exchanger arrangement including a first heat exchanger and a second heat exchanger, the first heat exchanger being configured to liquefy the high-pressure gaseous oxygen stream and at least one high-pressure gaseous air stream with a pressure greater than or equal to about 10 bar (absolute pressure) via indirect heat exchange with a refrigerant stream to produce a liquid oxygen stream and a liquid air stream; the second heat exchanger being configured to densify the liquid oxygen stream via indirect heat exchange with the liquid air stream to produce a dense liquid oxygen stream and a cold vaporized air stream; and (ii) one or more turbines configured to expand a branch portion of at least one high-pressure gaseous air stream to produce one or more exhaust streams. The refrigerant stream comprises a mixture of one or more exhaust streams and cold vaporized air streams. This system is preferably configured as a spacecraft launch platform located near a launch facility. High-pressure gaseous oxygen and at least one high-pressure gaseous air stream are preferably supplied to the launch facility via pipeline from an air separation unit located within a range of approximately 2 kilometers of the launch facility.

[0007] Alternatively, the present invention can be characterized as a method for preparing a dense liquid oxygen stream from a high-pressure gaseous oxygen stream, the method comprising the steps of: (a) liquefying the high-pressure gaseous oxygen stream and at least one high-pressure gaseous air stream with a pressure greater than or equal to about 10 bar (absolute pressure) via indirect heat exchange with a refrigerant stream in a heat exchanger arrangement to produce a liquid oxygen stream and a liquid air stream; (b) densifying the liquid oxygen stream via indirect heat exchange with the liquid air stream in a heat exchanger arrangement to produce a dense liquid oxygen stream and a cold vaporized air stream; (c) expanding a branch portion of at least one high-pressure gaseous air stream in one or more turbines to produce one or more exhaust streams; and (d) mixing one or more exhaust streams with the cold vaporized air stream to produce a refrigerant stream. The heat exchange arrangement preferably includes a first heat exchange device or heat exchange core and a second heat exchange device or heat exchange core, the first heat exchange device or heat exchange core being configured to liquefy high-pressure gaseous oxygen flow and at least one high-pressure gaseous air flow, and the second heat exchange device or heat exchange core being configured to densify liquid oxygen flow.

[0008] In various embodiments of this system and method, one or more auxiliary compressors may be present, configured to compress a high-pressure air stream to a pressure greater than or equal to about 50.5 bar (absolute pressure). Furthermore, the one or more turbines include a first turbine and a second turbine, the first turbine configured to expand a branch portion of at least one high-pressure gaseous air stream to generate a first exhaust stream, the second turbine configured to further expand the first exhaust stream to generate a second exhaust stream, and wherein the refrigerant stream comprises a mixture of the second exhaust stream and a cold vaporized air stream. Optionally, the one or more turbines may also include a third turbine configured to expand a second branch portion of the high-pressure gaseous air stream to generate a third exhaust stream, and wherein the second turbine is further configured to further expand the mixture of the first and third exhaust streams to generate the second exhaust stream. Preferably, the system and method also include an integral geared machine operatively coupled to the one or more turbines and the one or more auxiliary compressors. In such embodiments, the work provided by the one or more turbines is preferably equal to or greater than the work required by the one or more auxiliary compressors.

[0009] In most embodiments, at least a portion, preferably a majority of, of the high-pressure air stream is used for the liquefaction of the high-pressure gaseous oxygen stream. A second portion of the high-pressure air stream is liquefied and subsequently evaporated at a pressure equal to and preferably less than ambient pressure / atmospheric pressure. Optionally, a portion of the liquid air can be stored in a tank at the launch facility to provide additional flexibility in this refrigeration system and method. A significant advantage is also achieved by recovering sensible cold from the evaporation stream via a vacuum pump configured to pressurize the cold vaporized air stream and recirculate it as part of the refrigerant stream. Alternatively, the high-pressure air stream can be a conventional liquid air stream generated from a nearby air separation unit as part of an air separation cycle, or alternatively, a synthetic air stream comprising a mixture of oxygen and nitrogen from the air separation unit. Attached Figure Description

[0010] It is believed that the system and method protected by the claims will be better understood when viewed in conjunction with the accompanying drawings, in which:

[0011] Figure 1 A schematic diagram of the arrangement of the present invention is shown, which is used to prepare a dense liquid oxygen flow for use in spacecraft launch at the launch facility using a high-pressure gaseous oxygen flow and a high-pressure air flow from a nearby air separation unit;

[0012] Figure 2A schematic diagram of an embodiment of a system and method for liquefying a high-pressure gaseous oxygen stream and densifying the resulting liquid oxygen stream using a high-pressure air stream as a refrigerant is shown; and

[0013] Figure 3 A schematic diagram of an alternative embodiment of a system and method for liquefying a high-pressure gaseous oxygen stream and densifying the resulting liquid oxygen stream using a high-pressure air stream as a refrigerant is shown. Detailed Implementation

[0014] Compared to conventional oxygen densification systems and processes currently used in many spacecraft launch applications, this system and method for preparing dense liquid oxygen streams incorporates several innovative and / or advantageous features. A first advantageous feature involves pipelined transport of a high-pressure gaseous oxygen stream and a stream of high-pressure purified air from a nearby air separation unit to the liquefaction site, preferably at the launch facility. The high-pressure purified air provides the necessary pressure energy to facilitate liquid oxygen preparation and densification. This refrigeration required for oxygen liquefaction and densification is preferably generated using a gas expansion refrigeration process via a split section of the high-pressure purified air stream. A second innovative aspect of this system and method is the integration of the oxygen liquefaction process with the oxygen densification process. The use of a cryogenic liquefaction process with a high-pressure purified air stream allows for direct on-site integration of the densification process.

[0015] Another innovative aspect of this system and method involves the use of an integrated gear-type combined expander-compressor, such as a compressor-expander integrated unit or bridge unit (i.e., BRIM) that consumes virtually negligible power. Such a compressor-expander integrated unit or bridge unit can be used both to recover the energy or work from the gas expansion of the high-pressure purified air stream and as a device to redistribute power to the associated compression of the high-pressure purified air stream. In this way, little or no external power needs to be brought to the liquefaction site. Yet another innovation or advantage involves the use of multiple turboexpanders operatively coupled to the integrated gear-type machine to facilitate the efficient liquefaction of high-pressure gaseous oxygen streams. It has been found that using three turboexpanders enables oxygen liquefaction with high efficiency, in addition to one or more auxiliary feed air compressors operatively coupled to a three-gear compressor-expander integrated unit or bridge unit.

[0016] Turn now Figure 1This figure shows a highly simplified depiction of a general processing scheme for preparing a dense liquid oxidant and supplying it to a launch facility used in spacecraft launches. As shown, a high-pressure gaseous oxygen stream 20 is generated by an air separation unit 10 located near the spacecraft launch facility 30. The high-pressure gaseous oxygen stream 20 is delivered to the spacecraft launch facility 30 via oxygen conduits. Alternatively, a high-pressure air stream 25, or a synthetic air stream, consisting of a mixture of oxygen and nitrogen from the air separation unit, may also be guided from the air separation unit 10 to the spacecraft launch facility 30 via conduits. The high-pressure air stream 25 is preferably delivered to the launch facility 30 at a pressure equal to or greater than 10 bar (absolute pressure), and preferably greater than 20 bar (absolute pressure). Preferably, the air separation unit 10 is located within 2 kilometers of the launch facility 30. The high-pressure gaseous oxygen stream 20 and the high-pressure air stream 25 are guided to a combined liquefaction and densification system 40, at which, as described below... Figure 2 and Figure 3 In more detail, the high-pressure gaseous oxygen stream 20 is liquefied and the resulting liquid oxygen stream 44 is densified. Preferably, the high-pressure gaseous oxygen stream 20 may be further compressed at the launch facility and delivered to the liquefaction process in a supercritical state. The product obtained from the combined liquefaction and densification system / process is a dense liquid oxygen product 65, which may be stored in a tank 35 and used for rocket launch applications at one or more launch pads 33 located at the launch facility 30. The low-pressure exhaust gas stream 60 from the liquefaction and densification process / system may be discharged into the atmosphere, or optionally recycled back to the air separation unit, or used for other applications to clean and dry air.

[0017] Figure 1 The air separation unit 10 shown is equipped with conventional hot-end treatment equipment 14 and cold-end treatment equipment 16. The hot-end treatment equipment 14 within the air separation unit 10 typically includes a main feed air compressor unit and an air pre-purification unit configured to substantially compress and pre-purify the incoming feed air stream 12, as well as one or more turbine air circuits and / or booster air circuits. A portion of the substantially compressed and pre-purified air 15 is extracted from the hot-end treatment equipment 15 within the air separation unit 10 as a high-pressure purified air stream. The cold-end treatment equipment 16 within the air separation unit 10 typically includes a primary or secondary heat exchanger arrangement and a distillation column system, typically housed in one or more insulated cold boxes. The cold-end treatment equipment 16 within the air separation unit 10 is configured to cool a portion of the substantially compressed and purified air 15, and then fractionate or separate the cooled air in the distillation column system to produce a variety of products, including a high-pressure gaseous oxygen stream 20 and possible liquid nitrogen, liquid oxygen, or argon products.

[0018] exist Figure 1 In the arrangement depicted, liquid storage tanks are also preferably located at launch facility 30 to store dense liquid oxygen and optionally any liquid air, or other liquid products, such as liquid nitrogen or liquid fuel, generated within the combined liquefaction and densification system, for example, methane required at launch facility 30. Although not shown, the liquefaction and densification system and / or its components may be mounted on a movable platform that may be centrally located within launch facility 30 or easily moved to a location close to spacecraft launch pad 33 or platform within launch facility 30.

[0019] Turn now Figure 2 The illustrated liquefaction and densification system 40 and associated method preferably receive a high-pressure gaseous oxygen stream 20 at a pressure greater than or equal to 40 bar (absolute pressure), and more preferably at a pressure greater than about 60 bar (absolute pressure). The high-pressure gaseous oxygen stream 20 is directed to a first heat exchanger device 45 or heat exchanger core configured to cool and condense the high-pressure gaseous oxygen stream 20 via indirect heat exchange with a refrigerant stream to produce a liquid oxygen stream 44. The liquid oxygen stream 44 is then directed to a second heat exchanger device 55 configured to subcool or densify the resulting liquid oxygen stream 44 via indirect heat exchange with a liquid air stream 54 to produce a dense liquid oxygen stream 65 and a cold vaporized air stream 56.

[0020] The exemplified liquefaction and densification system 40 and associated method preferably receive one or more streams of high-pressure gaseous air 25 at a pressure greater than or equal to about 10 bar (absolute pressure), more preferably at a pressure greater than about 20 bar (absolute pressure), and most preferably at a pressure equal to or greater than about 25 bar (absolute pressure). The high-pressure gaseous air stream 25 may be further compressed in one or more auxiliary compressors 41 to a pressure at or near supercritical pressure. The further compressed high-pressure air stream is post-cooled in an aftercooler 42 and then directed to a first heat exchanger assembly 45 or heat exchanger core. A first branch of the further compressed high-pressure air stream 43 is pre-cooled or partially cooled and then branched as stream 46 to a first turbine 47 or a warm turbine expander. The first exhaust stream 48 exiting the first turbine 47 will typically approach saturation at a pressure preferably in the range of 5 bar (absolute pressure) to 10 bar (absolute pressure). The first exhaust stream 48 is partially heated in the first heat exchanger 45, and then the heated stream 49 is directed to a second turbine 50 or a cold turbine expander to further expand the heated first exhaust stream to a pressure slightly above ambient or preferably about 1.2 bar (absolute pressure) to generate a second exhaust stream 51. The second exhaust stream 51 is directed back to the first heat exchanger 45 as part of a cooling stream.

[0021] Another branch of the further compressed high-pressure air stream is completely cooled to a substantially liquefied state. The liquefied air stream 52 is then depressurized to a pressure below ambient pressure via expansion valve 53 and / or liquid turbine. The depressurized stream 54 is then substantially vaporized in a vacuum within the second heat exchanger 55 or the second heat exchanger core through indirect heat exchange with the liquid oxygen stream 44. The resulting cold vaporized air stream 56 is drawn through vacuum pump 57 and repressurized to a pressure just above ambient pressure, or preferably repressurized to approximately 1.2 bar (absolute pressure). The repressurized cold vaporized air stream 58 is guided back to the first heat exchanger 45 as part of a refrigeration stream. Thus, the refrigeration stream used for liquefying the high-pressure gaseous oxygen stream 20 and a portion or branch of the high-pressure liquefied air stream 52 comprises a mixture of one or more exhaust streams 51 and cold vaporized air streams 58.

[0022] The work generated by the expansion of a portion of the high-pressure airflow in the first and second turbines is preferably directed to the integral geared compression-expansion unit, so that this work can be recovered for further compression of the incoming high-pressure airflow or feed high-pressure airflow in one or more auxiliary compressors 41 and / or vacuum pump 57. Ideally, the further compression of the feed high-pressure airflow in one or more auxiliary compressors 41 and the repressurization of the cold vaporized airflow below ambient pressure are defined as enabling an energy balance to be established within the integral geared compression-expansion unit without inputting or outputting additional electrical power. However, in practice, the work provided by one or more turbines 47, 50 should be greater than 90% of the work required by one or more auxiliary compressors 41 and vacuum pump 57.

[0023] Figure 3 The schematic diagrams and process flow charts depicted in the above are consistent with those described above. Figure 2 The schematic diagrams and process flow diagrams are very similar, and for the sake of simplicity, many detailed descriptions of the layout will not be repeated. Instead, the following discussion will focus on... Figure 3 The process flow diagram depicts the same as Figure 2 The differences and additions between the process flow diagrams depicted in the previous version and the current version.

[0024] exist Figure 3 In one embodiment, the high-pressure gaseous oxygen stream 20, preferably at a pressure greater than or equal to 40 bar (absolute pressure) and more preferably at a pressure greater than about 60 bar (absolute pressure), is cooled and condensed in the first heat exchange device 45, and the resulting liquid oxygen stream 44 is then subcooled in the second heat exchange device 55 via indirect heat exchange with the liquid air stream 54 to produce a dense liquid oxygen stream 65 and a cold vaporized air stream 56.

[0025] Figure 2 Implementation plan and Figure 3The key difference between the implementation schemes is that the high-pressure gaseous air stream 25 is further compressed to supercritical pressure and then split into three streams. Similar to... Figure 2 In this embodiment, a first branch of the further compressed high-pressure airflow 46 is diverted to a first turbine 47, where it is expanded to produce a first exhaust flow 48. A second branch of the further compressed high-pressure airflow is completely cooled to a substantially liquefied state in a first heat exchanger 45. The liquefied airflow 52 is then depressurized to a pressure below ambient pressure via an expansion valve 53 and / or a liquid turbine. A third branch of the further compressed high-pressure airflow is cooled in the first heat exchanger 45, and the cooled flow 66 is diverted to a third turbine 67, where it is expanded to produce a third exhaust flow 68.

[0026] The first exhaust stream 48 and the third exhaust stream 68 may both be heated in different heating channels within the first heat exchanger 45 and then mixed. The resulting mixed exhaust stream 49 is then directed to a second turbine 50 or a cold turbine expander, which is used to further expand the mixed exhaust stream to a pressure slightly above ambient or preferably about 1.2 bar (absolute pressure) to produce a second exhaust stream 51. The second exhaust stream 51 is then directed back to the cold end of the first heat exchanger 45 as part of a cooling stream. It should be noted that in this embodiment, the temperature of the third turbine exhaust 68 is comparable to the temperature of the second turbine exhaust 51.

[0027] Similar to Figure 2 Implementation plan, Figure 3 In the embodiment, the resulting cold vaporized airflow 56 is drawn through the vacuum pump 57 and repressurized to approximately 1.2 bar (absolute pressure). The repressurized cold vaporized airflow 58 can be combined with the low-pressure exhaust flow 51 of the second turbine 50 to form a refrigerated flow. The combined refrigerated flow is then heated to ambient temperature, and the resulting low-pressure airflow 60 is preferably discharged or recirculated back to the air separation unit 10. Industrial applicability

[0028] The most significant technical advantage of this system and method for preparing a dense liquid oxygen stream from a pipeline-supplied high-pressure gaseous oxygen stream using a pipeline-supplied high-pressure air stream as a refrigerant is the elimination of the need to transport liquid oxygen and / or liquid nitrogen to the launch facility by truck. Furthermore, no additional refrigeration system is required for the densification of the liquid oxygen. By integrating oxygen densification with liquefaction using a high-pressure air stream, the single-use of liquid nitrogen in conventional oxygen densification processes is significantly reduced, if not eliminated. The use of an integrated compressor-expander or bridge-type compressor to recover the gas expansion electricity from the turbine expansion of the high-pressure air stream enables a highly efficient liquefaction process and may eliminate the capital investment associated with expanding high-pressure power supplies at the launch facility for oxygen liquefaction and densification purposes.

[0029] In spacecraft launch applications requiring liquid oxygen at 1000+ mtpd, the liquid nitrogen-to-liquid oxygen ratio (LN2 / LO2) supplied externally is approximately 0.4. It can be anticipated that eliminating this need for liquid nitrogen would result in potential power savings of approximately 10 MW from the air separation unit. This reduction in liquid nitrogen requirements will also significantly simplify the design of the air separation unit and air separation cycle required for supplying high-pressure oxygen without liquid nitrogen. The pure gas air separation unit, designed primarily to produce the high-pressure gaseous oxygen and high-pressure air streams required by this system and method, will likely require only a single turbine and booster air compressor. The capital cost savings from the air separation unit compared to the dedicated, integrated air separation and liquefaction units currently used to supply liquid oxygen and liquid nitrogen to customers in space applications are likely to reach millions of dollars.

[0030] While the present system and method for preparing dense liquid oxygen products have been described with reference to one or more preferred embodiments, it should be understood that various modifications, additions, alterations, and omissions may be made without departing from the spirit and scope of the present system and method as set forth in the appended claims.

[0031] For example, regarding air compression, dedicated air compression for refrigeration preparation is possible. Main air compression and associated pre-purification can occur at either or both locations, namely the air separation unit or the launch facility. Furthermore, the main air compression, as well as auxiliary compression, can be arranged in series or parallel configurations based on flow and pressure requirements from space application customers and any auxiliary requirements, such as the supply of commercial liquids or the need for liquid air energy storage. Air pre-purification requirements can also be distributed between the air separation unit and the launch facility. For example, high-pressure gaseous air supplied to the launch facility via piping can initially be dehydrated via absorption at the air separation unit and then piped to the launch facility, where it can be further dried to a cryogenic-ready state.

[0032] To increase the diversion of liquid air, liquid turbines or dense-phase expanders can be used to reduce subsequent flash evaporation losses. Such machines can be configured in series with subsequent valves to completely reduce the liquid air pressure before it enters the second heat exchanger for densification.

[0033] Furthermore, while liquefying supercritical oxygen at pressures >50.5 bar (absolute pressure) is thermodynamically preferred, the aforementioned system and method can be configured for lower oxygen pressures. Additionally, the oxygen can be further compressed at the air separation unit (ASU) or launch pad. Such compression can be integrated into an integral geared machine.

[0034] The process can operate without overall liquid oxygen densification, or it can operate with intermittent liquid oxygen densification, in which case the undensified liquefied oxygen is simply stored in one or more tanks at the launch facility for subsequent densification or use. It is also conceivable to use different densification refrigerants, such as rare gases, argon, or even liquid nitrogen, to supplement or replace densification units. Methane densification can also be combined with oxygen densification in the densification process. Alternatively, the current liquefaction process can be designed to also incorporate a high-pressure air stream as a refrigerant to liquefy a small stream of gaseous nitrogen from the air separation unit, with the resulting liquid nitrogen then stored in tanks or used to supplement densification or methane densification.

[0035] While it is advantageous to integrate the gas expander of the present invention into a conventional single BRIM type machine, this is not mandatory. Alternatively, the turbine or turbine expander of the present invention can be connected to a high-speed generator, or the electricity can be dissipated to the brake. It should be noted that a vacuum compressor can also be integrated into the BRIM type machine. If electricity is available, the BRIM can employ an electric motor (or generator). The auxiliary compressor can also be configured as a dedicated booster compressor, and one or more of the auxiliary compressors can be operatively coupled to one or more turbines in the turbine.

Claims

1. A system for preparing a dense liquid oxygen stream from a high-pressure gaseous oxygen stream, the system comprising: A heat exchanger arrangement comprising a first heat exchanger and a second heat exchanger, the first heat exchanger being configured to liquefy the high-pressure gaseous oxygen stream and at least one high-pressure gaseous air stream with a pressure greater than or equal to about 10 bar (absolute pressure) via indirect heat exchange with a refrigerant stream to produce a liquid oxygen stream and a liquid air stream; the second heat exchanger being configured to densify the liquid oxygen stream via indirect heat exchange with the liquid air stream to produce a dense liquid oxygen stream and a cold vaporized air stream. One or more turbines, the one or more turbines being configured to expand a split portion of the at least one high-pressure gaseous air stream to generate one or more exhaust streams; The refrigerant stream comprises a mixture of one or more exhaust streams and the cold vaporized air stream.

2. The system for preparing the dense liquid oxygen flow according to claim 1, wherein the one or more turbines further comprises: A first turbine, configured to expand a portion of the at least one high-pressure gaseous air stream to generate a first exhaust stream; and A second turbine is configured to further expand the first exhaust flow to generate a second exhaust flow; The refrigerant flow comprises a mixture of the second exhaust flow and the cold vaporized air flow.

3. The system for preparing the dense liquid oxygen flow according to claim 2, wherein the first heat exchange device is further configured to precool the high-pressure air flow, and the first turbine is configured to expand the precooled high-pressure air flow to generate the first exhaust flow.

4. The system for preparing the dense liquid oxygen stream according to claim 2, wherein the first heat exchange device is further configured to partially heat the first exhaust stream, and the second turbine is configured to expand the partially heated first exhaust stream to generate the second exhaust stream.

5. The system for preparing the dense liquid oxygen stream according to claim 1, the system further comprising one or more auxiliary compressors configured to compress the high-pressure air stream to a pressure greater than or equal to about 50.5 bar (absolute pressure).

6. The system for preparing the dense liquid oxygen flow according to claim 5, wherein the work provided by the one or more turbines is equal to or greater than the work required by the one or more auxiliary compressors.

7. The system for preparing the dense liquid oxygen stream according to claim 6, the system further comprising an integral geared machine operatively coupled to the one or more turbines and the one or more auxiliary compressors.

8. The system for preparing the dense liquid oxygen stream according to claim 6, wherein the cold vaporized air stream is at a pressure below ambient pressure, and the system further includes a vacuum pump configured to pressurize the cold vaporized air stream.

9. The system for preparing the dense liquid oxygen flow according to claim 8, wherein the work provided by the one or more turbines is greater than 90% of the work required by the one or more auxiliary compressors and the vacuum pump.

10. The system for preparing the dense liquid oxygen stream according to claim 2, the system further comprising: A third turbine is configured to expand another branch portion of the at least one high-pressure gaseous airflow to generate a third exhaust flow; and The second turbine is further configured to further expand the mixture of the first exhaust stream and the third exhaust stream to generate the second exhaust stream.

11. The system for preparing the dense liquid oxygen stream according to claim 10, wherein the first heat exchange device is further configured to partially heat the first exhaust stream and the third exhaust stream, and the second turbine is configured to expand the mixture of the partially heated first exhaust stream and the partially heated third exhaust stream to generate the second exhaust stream.

12. The system for preparing the dense liquid oxygen stream according to claim 1, wherein the first heat exchanger, the second heat exchanger, and the one or more turbines are configured as a spacecraft launch platform near the launch facility.

13. The system for preparing the dense liquid oxygen stream according to claim 12, wherein the high-pressure gaseous oxygen and the at least one high-pressure gaseous air stream are supplied to the launch facility via a pipeline from an air separation unit located within a 2-kilometer radius of the launch facility.

14. The system for preparing the dense liquid oxygen stream according to claim 13, wherein the at least one high-pressure gaseous air stream comprises a synthetic air stream, the synthetic air stream comprising a mixture of oxygen and nitrogen from the air separation unit.

15. The system for preparing the dense liquid oxygen stream according to claim 12, the system further comprising a storage tank, wherein the dense liquid oxygen stream is stored in the storage tank for use as an oxidant in a spacecraft propulsion system.

16. A method for preparing a dense liquid oxygen stream from a high-pressure gaseous oxygen stream, the method comprising the following steps: The high-pressure gaseous oxygen stream and at least one high-pressure gaseous air stream with a pressure greater than or equal to 10 bar (absolute pressure) are liquefied via indirect heat exchange with the refrigerant stream in a heat exchanger arrangement to produce a liquid oxygen stream and a liquid air stream. The liquid oxygen flow is densified via indirect heat exchange with the liquid air flow in the heat exchange arrangement to generate the dense liquid oxygen flow and the cold vaporized air flow; The heat exchange arrangement includes a first heat exchange device and a second heat exchange device, wherein the first heat exchange device is configured to liquefy the high-pressure gaseous oxygen stream and at least one high-pressure gaseous air stream, and the second heat exchange device is configured to densify the liquid oxygen stream; The split portion of the at least one high-pressure gaseous air stream is expanded in one or more turbines to generate one or more exhaust streams; The one or more exhaust streams are mixed with the cold vaporized air stream to generate the refrigerant stream.

17. The method for preparing a dense liquid oxygen flow according to claim 16, wherein the one or more turbines further comprises: A first turbine, configured to expand a portion of the at least one high-pressure gaseous air stream to generate a first exhaust stream; and A second turbine is configured to expand the first exhaust flow to generate a second exhaust flow; The refrigerant flow comprises a mixture of the second exhaust flow and the cold vaporized air flow.

18. The method for preparing the dense liquid oxygen stream according to claim 17, the method further comprising the step of precooling the at least one high-pressure air stream in the first heat exchanger, and wherein the step of expanding the split portion of the at least one high-pressure gaseous air stream in the first turbine further comprises expanding the precooled at least one high-pressure air stream to generate the first exhaust stream.

19. The method for preparing the dense liquid oxygen stream according to claim 17, the method further comprising the step of partially heating the first exhaust stream, and wherein the step of expanding the first exhaust stream further comprises expanding the partially heated first exhaust stream to generate the second exhaust stream.

20. The method for preparing a dense liquid oxygen stream according to claim 16, the method further comprising the step of compressing the at least one high-pressure air stream to a pressure greater than or equal to about 50.5 bar (absolute pressure) in one or more auxiliary compressors.

21. The method for preparing the dense liquid oxygen flow according to claim 20, wherein the work provided by the one or more turbines is equal to or greater than the work required by the one or more auxiliary compressors.

22. The method of claim 20 for preparing the dense liquid oxygen stream, wherein the cold vaporized air stream is at a pressure below ambient pressure, and the method further comprises the step of pressurizing the cold vaporized air stream with a vacuum pump, and wherein the work provided by the one or more turbines is greater than 90% of the work required by the one or more auxiliary compressors and the vacuum pump.

23. The method for preparing the dense liquid oxygen stream according to claim 17, the method further comprising the following steps: In the third turbine, the second branch portion of the high-pressure gaseous airflow is expanded to generate a third exhaust flow; as well as In the first heat exchange device, the first exhaust stream and the third exhaust stream are mixed; and The step of expanding the first exhaust flow in the second turbine further includes expanding the mixture of the first exhaust flow and the third exhaust flow in the second turbine to generate the second exhaust flow.

24. The method for preparing the dense liquid oxygen stream according to claim 23, the method further comprising the step of partially heating the first exhaust stream and the third exhaust stream in the first heat exchanger, and wherein the step of further expanding the first exhaust stream in the second turbine further comprises further expanding the mixture of the first exhaust stream and the third exhaust stream in the second turbine to generate the second exhaust stream.

25. The method for preparing the dense liquid oxygen stream according to claim 16, the method further comprising the step of supplying the at least one high-pressure gaseous oxygen and the high-pressure gaseous air stream from the air separation unit to a launch facility located within a 2-kilometer radius of the air separation unit via a pipeline.

26. The method for preparing the dense liquid oxygen stream according to claim 25, wherein the at least one high-pressure gaseous air stream comprises a purified air stream from the air separation unit.

27. The method for preparing the dense liquid oxygen stream according to claim 25, wherein the at least one high-pressure gaseous air stream comprises a purified synthetic air stream, the purified synthetic air stream comprising a mixture of oxygen and nitrogen generated by the air separation unit.

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