Patent Application
20240369293
The present innovation relates to processes and systems for the recovery of oxygen during the production of hydrogen gas obtained via one or more electrolyzers.
Electrolyzers can produce hydrogen from water via electrolysis. Examples of electrolyzers that produce hydrogen gas can be appreciated from U.S. Pat. Nos. 5,512,145 and 9,328,426 as well as U.S. Patent Application Publication No. 2022/0283567, European Patent Publication No. EP4001462, German Patent Publication No. DE102019008985A1, International Publication No. WO 2021/160235, Chinese Patent Publication Nos. CN114214637A, CN113562701A, CN101407921A, and Chinese Utility Model Patent Nos. CN203923390U and CN210512327U. While the hydrogen produced by the electrolyzers may be used in downstream processes, the non-hydrogen fluid output from the electrolyzers is often vented to atmosphere.
Cryogenic processes for production of liquid oxygen or nitrogen can be appreciated from U.S. Pat. Nos. 6,220,053, 5,157,926, and 10,852,061 as well as U.S. Pat. App. Pub. No. 2022/0099364. Such systems are typically designed to limit waste and ensure high yield recovery. Such systems often include a feed compressor as well as a recycle compressor to provide sufficient pressure to facilitate the flow of feed and recycling of feed in the cryogenic process utilized to form liquid oxygen or other liquid fluid (e.g., liquid nitrogen).
We determined that oxygen gas can be recovered as liquid oxygen (LOX) in situations where the oxygen gas may be available from at least one electrolyzer at an elevated pressure (e.g. greater than or equal to 10 bar absolute (bara), greater than or equal to 20 bara, at least 20 bara and less than 50 bara, etc.). The oxygen gas flow output from the electrolyzer(s) can be separate from a hydrogen gas flow output from the electrolyzer(s). The oxygen gas flow can be comprised of at least 80 volume percent (vol %) oxygen, at least 90 vol % oxygen, between 90 vol % oxygen and 100 vol % oxygen, or between 98 vol % oxygen and 100 vol % oxygen) in some embodiments.
We determined that such a flow of oxygen gas can be used to recover liquified oxygen from that oxygen gas via expansion without use of a feed compressor or recycle compressor for providing a portion of the oxygen as liquid oxygen. Embodiments can be configured as an open loop process in which the non-recovered oxygen gas that was not liquified via the liquefaction expansion process can be vented to atmosphere. Surprisingly, although this type of once-through expansion approach has a low yield for liquid oxygen formation, we determined that it can provide a favorable return as compared to a conventional high recovery process that utilizes a feed compressor and a recycle compressor (or just a feed compressor or just a recycle compressor). We determined that this is at least in part because high operational costs and capital costs associated with the feed and/or recycle compressor can be avoided, and the inherent safety risks surrounding oxygen compression can also be abated. Embodiments can provide a lower-cost process that can be attractive for recovering a useful product from an otherwise wasted stream, even at low yield (e.g. recovery of between 10% and 25% of the oxygen gas output from the electrolyzer(s) as liquid oxygen, recovery of between 5% and 30% of the oxygen gas output from the electrolyzer(s) as liquid oxygen, recovery of not more than 35% of the oxygen gas output from the electrolyzer(s) as liquid oxygen (e.g. between 5% and 35%), etc.). Some embodiments can be provided so that no feed compressor and no recycle compressor are needed or utilized. Other embodiments can be provided so that no feed compressor or no recycle compressor is needed or utilized.
Some embodiments can be configured so that no oxygen gas compression occurs in the processing for the recovery of the oxygen as LOX. Other embodiments can be configured so that the one or more expanders of the process are included in one or more companders such that the compressor component of the compander can be utilized in conjunction with the expander of the compander to provide a low cost compression of the oxygen gas for subsequent expansion via the expander that is primarily powered by operation of the expander of the compander.
It should be understood that a compander is not considered a feed compressor or a recycle compressor. A compander is a device that includes at least one compressor stage and at least one expander stage that are linked together so that expansion provided by the expander of the compander facilitates powering of the compressor of the compander. Companders are not considered feed compressors or recycle compressors because companders typically handle much less compression duty than a motor-driven feed compressor or recycle compressor. This is because the compressor component of the compander is driven primarily (or often exclusively) by a link to an expander, whereas feed compressors or recycle compressors are motor-driven. Thus, companders are often only capable of small compression ratios (e.g., roughly one stage of compression, or compression ratio less than about 2 when the flows are balanced), while a feed compressor or recycle compressor will often be designed as a multi-stage machine capable of much higher total compression ratios. Consequently, when the term “feed compressor” is used herein, this term does not include a compander. Also, when the term “recycle compressor” is used herein, this term does not include a compander.
Most modern liquefaction cycles operate with a feed pressure of about 80 bara. Most modern liquefaction cycles expand down to a recycle pressure of about 5 bara. This slightly elevated pressure is chosen for several reasons, including facilitation of recycling of the vapor stream, etc. A surprising finding is that embodiments of our process and apparatus can produce enough liquid oxygen product to be attractive compared to conventional recycle-based liquefaction cycles commonly in practice despite being able to be configured for use at lower feed pressures and lower expander discharge pressures.
Furthermore, it was surprisingly found that embodiments of our apparatus and process can offer an improvement over prior art methods of producing small amounts of liquid oxygen. Embodiments of our process and apparatus can be surprisingly configured to offer a straightforward method for recovering a relatively small yield (e.g. about 10% to 20% in some embodiments) of this flow as LOX at 1 bara with no net power consumed (or a small amount of power exported or consumed). In contrast, conventional approaches we are aware of suggest that the gaseous oxygen (GOX) could be expanded to 1 bara to recover power, and a recycle liquefier should be employed (using nitrogen or another suitable working fluid) to liquefy the GOX. Such a conventional recycle liquefier may often have a specific power of approximately 360 kWh/tonne of LOX, or 41.5 KJ/mol and the power recovered by expanding the GOX would need to equal 41.5/5 or 8.3 KJ/mol to have the same net power. For an expander operating between 20 bara and 1.2 bara with an isothermal efficiency of 85%, the temperature would need to be approximately T=8300/8.314/ln(20/1.2)/0.85 K, or 144° C. Such a conventional approach can require a heat source significantly above ambient temperature to match the net power consumption while also requiring significant additional equipment (i.e., the recycle compressor, the additional power expander, and a heat exchanger for heating the GOX prior to expansion). Embodiments of our process and apparatus have been surprisingly found to avoid having to include such features to provide LOX as a product stream.
We have determined that embodiments of our process and apparatus for liquid oxygen recovery can be implemented to help reduce waste and further improve the efficiency and operation of hydrogen production processes that utilize electrolyzers. Such processes can help provide improved opportunities for low carbon intensity systems used for formation of hydrogen (e.g., green hydrogen production processes) which can help provide an improvement in environmental operation of hydrogen production systems while also permitting an additional liquid oxygen product to be formed and reducing waste to be vented from operation of such systems.
Additionally, we have determined that embodiments can provide an improvement in safety. An oxygen gas feed compressor and/or recycle compressor can include an inherent safety risk (e.g., fire or an explosion). Also, a compressor for oxygen gas is often more expensive and less efficient than a compressor for inert industrial gases due to special materials, increased clearances, and other design requirements often used to mitigate the safety risks associated with compression of oxygen (e.g. avoiding an explosion or a fire, etc.). Avoidance of such compressors and/or of any oxygen gas compression at all can help improve safety associated with liquid oxygen production.
Further, embodiments of the apparatus can also be configured so that there is no need for any other flows of fluid for use of the apparatus beyond the feed provided by the electrolyzer(s). For instance, embodiments can be provided that do not need a cryogenic fluid or other type of cooling medium from another plant or source beyond the feed to facilitate liquefaction of the oxygen of the feed into LOX. Instead, the oxygen vapor from phase separation can be utilized as the only cooling medium used to facilitate liquefaction of the oxygen. The combination of expansion and use of the expanded oxygen gas vapor for cooling and liquefaction can help avoid use of other cooling medium fluids and can permit embodiments of the apparatus to be more effectively incorporated into a plant via a retrofit operation, for example, and also have a simpler arrangement that may need a smaller overall footprint.
In a first aspect, an apparatus for liquid oxygen production can include a purification unit positioned to receive a feed from at least one electrolyzer and output the feed as a purified feed. The feed can include oxygen and have a pressure that is within a pre-selected feed pressure range. The apparatus can also include a heat exchanger positioned to receive at least a portion of the purified feed outputtable from the purification unit to cool the purified feed and output at least one stream of cooled purified feed and a first expander positioned to receive at least a first stream of cooled purified feed of the at least one stream of cooled purified feed outputtable from the heat exchanger to expand the first stream of cooled purified feed and output an expanded purified feed stream. A first phase separator can be positioned to receive the expanded purified feed stream to form a first liquid oxygen (LOX) stream and a first oxygen vapor stream to feed the first oxygen vapor stream to the heat exchanger as a cooling medium for the heat exchanger.
Embodiments can be provided so that the feed receivable at the purification unit is provided directly from one or more electrolyzers or can be provided indirectly from one or more electrolyzers (e.g. the oxygen containing feed can be passed through a storage unit or other type of intermediate unit prior to being fed to the purification unit). The pre-selected feed pressure can be any suitable pressure (e.g. a pressure of at least 5 bar absolute (bara), a pressure of at least 20 bara, a pressure of between 5 bara and 30 bara, etc.). Embodiments of the apparatus can be configured and adapted to perform an exemplary embodiment of our process for LOX production as discussed herein as well.
In a second aspect, the oxygen content of the feed can be between 90 volume percent (vol %) of the feed and 100 vol % of the feed and the pressure that is within the pre-selected feed pressure range is a pressure between 5 bar absolute (bara) and 50 bara. As discussed herein, in other embodiments another oxygen content range or pre-selected feed pressure range can be utilized as may be suitable for a particular set of design objectives.
In a third aspect, a second phase separator can be positioned so that a second purified feed stream of the at least one stream of cooled purified feed outputtable from the heat exchanger is feedable to the second phase separator for formation of a second oxygen vapor stream and a second LOX stream. The second phase separator can be connected to the heat exchanger so that the second oxygen vapor stream is feedable to the heat exchanger as a cooling medium to cool the purified feed fed to the heat exchanger before the second oxygen vapor stream is vented. In some implementations, the first LOX stream output from the first phase separator can be fed to the second phase separator for formation of the second LOX stream. In other implementations, the first LOX stream and the second LOX stream can be fed to LOX storage either separately or after being merged after the first LOX stream is output from the first phase separator and the second LOX stream is output from the second phase separator.
In a fourth aspect, a second expander can be provided. In some implementations, the second expander can be positioned to receive the first oxygen vapor stream from the heat exchanger after the first oxygen vapor stream is warmed from passing through the heat exchanger as a second expander feed stream to expand the first oxygen vapor stream for feeding to the heat exchanger as an expanded cooling medium stream. In other implementations, the second expander can be positioned to receive a bypass stream portion of the purified feed output form the purification unit. This bypass stream portion can be considered a second stream of the purified feed output from the purification unit that may be split from a first purified feed stream or can be considered a third purified feed stream that may be split from first and second purified feed streams that may be formed for undergoing cooling in the heat exchanger for forming LOX. The bypass stream portion may bypass the heat exchanger so it is never cooled therein and can be fed to the second expander for undergoing expansion for subsequently being fed to the heat exchanger as an expanded cooling medium stream for cooling the first purified feed stream (as well as a second purified feed stream if such a stream is also utilized).
In a fifth aspect, the apparatus can include a first compander. In some implementations, the first expander can be an expander of the first compander and the first compander can also have at least one first compression stage positioned to compress at least a portion of the purified feed stream to a pre-selected cooling feed pressure before it is fed to the heat exchanger. The first expander can be interconnected to the at least one first compression stage such that expansion of the first stream of the cooled purified feed outputtable from the heat exchanger at least partially powers compression of the at least one first compression stage of the compander.
In other embodiments in which the second expander is utilized, the second expander can be an expander of the first compander and the first compander can also have at least one first compression stage positioned to compress at least a portion of the purified feed stream to a pre-selected cooling feed pressure before it is fed to the heat exchanger. The second expander can be interconnected to the at least one first compression stage such that expansion of the second expander (e.g. expanding a bypass stream portion or expanding the warmed first oxygen vapor stream fed to the second expander as a second expander feed stream) at least partially powers compression of the at least one first compression stage of the compander.
In some embodiments, at least a portion of the purified feed outputtable from the purification unit can include a first stream of the purified feed and a second stream of the purified feed. A first compander can be provided wherein the first expander is an expander of the first compander and the first compander also has at least one first compression stage positioned to compress the first stream of the purified feed before it is fed to the heat exchanger. The first expander can be interconnected to the at least one first compression stage such that expansion of the first stream of cooled purified feed outputtable from the heat exchanger at least partially powers compression of the at least one first compression stage of the compander. Some of these embodiments can also utilize a second expander positioned to receive the first oxygen vapor stream from the heat exchanger after the first oxygen vapor stream is warmed from passing through the heat exchanger as a second expander feed stream to expand the first oxygen vapor stream for feeding to the heat exchanger as an expanded cooling medium stream.
In a sixth aspect, the apparatus can include multiple companders. For example, a first compander can be provided wherein the first expander is an expander of the first compander and the first compander also has at least one first compression stage positioned to compress a first stream of the purified feed before it is fed to the heat exchanger or a second stream of the purified feed. The first expander can be interconnected to the at least one first compression stage such that expansion of the first expander at least partially powers compression of the at least one first compression stage of the compander. A second compander can also be provided that includes a second expander and at least one second compression stage. The second expander can be positioned to receive the first oxygen vapor stream from the heat exchanger after the first oxygen vapor stream is warmed from passing through the heat exchanger or can be positioned to receive the second stream of the purified feed as a second expander feed stream to expand the stream for feeding to the heat exchanger as an expanded cooling medium stream. The at least one second compression stage of the second compander can be positioned to compress the first stream of the purified feed before it is fed to the heat exchanger or the second stream of the purified feed. The second expander can be interconnected to the at least one second compression stage such that expansion of the second expander at least partially powers compression of the at least one second compression stage of the compander.
In a seventh aspect, the apparatus can include a second phase separator that is positioned so that a second purified feed stream output from the heat exchanger is feedable to the second phase separator for formation of a second oxygen vapor stream and a second LOX stream. The second phase separator can be connected to the heat exchanger so that the second oxygen vapor stream is feedable to the heat exchanger as a cooling medium to cool the purified feed fed to the heat exchanger before the second oxygen vapor stream is vented.
In an eighth aspect, the apparatus can be positioned and configured to form LOX from the feed at a yield of between 5% and 35% without a feed compressor and/or without a recycle compressor. For example, embodiments can be provided to form LOX from the feed at a yield of between 5% and 35% without a feed compressor and without a recycle compressor. As another example, embodiments can be provided to form LOX from the feed at a yield of between 5% and 35% without a feed compressor. As yet another example, embodiments can be provided to form LOX from the feed at a yield of between 5% and 35% without a recycle compressor.
In a ninth aspect, the apparatus can be positioned and configured as an open loop arrangement for the feed that only uses fluid from the feed as a cooling medium for the heat exchanger. Some embodiments can be provided so that no other cooling medium is utilized for forming of the LOX other than a portion of the fluid of the feed, for example.
In a tenth aspect, a second expander can be positioned to receive a bypass portion of the purified feed outputtable from the purification unit to expand the bypass portion for feeding to the heat exchanger as a cooling medium. The heat exchanger can be positioned to receive a first stream of the purified feed outputtable from the purification unit to cool the first stream of the purified feed and output the first stream of the purified feed for feeding to the first expander. In such embodiments, the purified feed outputtable from the purification unit can include a purified feed that is split to form the first stream of the purified feed and the bypass portion of the purified feed.
In some embodiments, the purified feed can be split to also form a second stream of the purified feed as well as the first stream of the purified feed. Such a split can occur prior to the streams being fed to the heat exchanger or while the first stream of the purified feed is in the heat exchanger. In such embodiments, the bypass portion of the purified feed can be considered a third stream of the purified feed.
In an eleventh aspect, the apparatus can be arranged and configured so that at least a portion of the purified feed outputtable from the purification unit or the at least one stream of cooled purified feed outputtable from the heat exchanger includes a first stream of the purified feed and a second stream of the purified feed. The first phase separator can be positioned such that the second stream of the purified feed is outputtable from the heat exchanger to bypass the first expander for being fed to the first phase separator while the first stream of the purified feed is outputtable from the heat exchanger as the first stream of cooled purified feed for being fed to the first expander.
In a twelfth aspect, embodiments of the apparatus can include additional features and combinations of the above noted aspects. For example, the first aspect of the apparatus can include one or more features of the second aspect, third aspect, fourth aspect, fifth aspect, sixth aspect, seventh aspect, eighth aspect, ninth aspect, tenth aspect, and eleventh aspect. It should therefore be appreciated that other embodiments of the apparatus can include a subset of features of other aspects to provide yet additional embodiments.
In a thirteenth aspect, an apparatus for liquid oxygen production, the apparatus can include a purification unit positioned to receive a feed from at least one electrolyzer and output the feed as a purified feed. The feed can include oxygen and have a pressure that is within a pre-selected feed pressure range. A heat exchanger can be positioned to receive at least a portion of the purified feed outputtable from the purification unit to cool the purified feed and output at least one stream of cooled purified feed. A first expander can be positioned to receive at least a first stream of cooled purified feed of the at least one stream of cooled purified feed outputtable from the heat exchanger to expand it and output an expanded purified feed stream to feed to the heat exchanger as a cooling medium. A first phase separator can be positioned to receive a second stream of the at least one stream of cooled purified feed outputtable from the heat exchanger to form a first liquid oxygen (LOX) stream and a first oxygen vapor stream to feed the first oxygen vapor stream to the heat exchanger as a cooling medium for the heat exchanger.
In a fourteenth aspect, a process for forming liquid oxygen (LOX) from a feed output from at least one electrolyzer is provided. Embodiments of the process can be utilized in an embodiment of the apparatus as discussed herein, for example. The feed of the process can include oxygen and can be at a pressure that is within a pre-selected feed pressure range. The process can include receiving the feed and purifying the feed to form a purified feed, cooling at least a portion of the purified feed via a heat exchanger and at least one expander to form a cooled feed, separating the cooled feed to form at least one stream of LOX and at least one stream of oxygen vapor, and feeding each stream of the at least one stream of oxygen vapor to the heat exchanger as a cooling medium for cooling the purified feed.
In a fifteenth aspect, the feed of the process can include an oxygen content of between 90 volume percent (vol %) of the feed and 99 vol % of the feed and the pressure that is within the pre-selected feed pressure range can be a pressure between 5 bar absolute (bara) and 50 bara. Other embodiments may utilize other suitable pressures or oxygen content ranges.
In a sixteenth aspect, the at least one expander can include a first expander and the process can include compressing at least a portion of the feed via at least one first compression stage of a first compander. The first expander can be an expander of the first compander and the first expander can be interconnected to the at least one first compression stage of the first compander such that expansion of at least a portion of the purified feed at least partially powers compression of the at least a portion of the feed provided by the at least one first compression stage.
In a seventeenth aspect, the at least one stream of LOX is formed from the feed can be at a yield of between 5% and 35% without a feed compressor and/or without a recycle compressor. For example, embodiments of the process can be provided to form LOX from the feed at a yield of between 5% and 35% without a feed compressor and without a recycle compressor. As another example, embodiments of the process can be provided to form LOX from the feed at a yield of between 5% and 35% without a feed compressor. As yet another example, embodiments of the process can be provided to form LOX from the feed at a yield of between 5% and 35% without a recycle compressor.
In an eighteenth aspect, the process can be arranged and utilized as an open loop processing arrangement for the feed that only uses fluid from the feed as a cooling medium for the heat exchanger. Some embodiments of the process can be provided so that no other cooling medium is utilized for forming of the LOX other than a portion of the fluid of the feed, for example.
In a nineteenth aspect, the process can include outputting the at least one stream of oxygen vapor from the heat exchanger as a warmed at least one stream of oxygen vapor for venting and/or use as a regeneration gas.
In a twentieth aspect, the process can be performed in such a way that the feed is not compressed to a higher pressure via a feed compressor and the at least one stream of oxygen vapor is not compressed to a higher pressure via a recycle compressor.
In a twenty-first aspect, the process can be performed so that the cooling of at least a portion of the purified feed via the heat exchanger and at least one expander comprises splitting the purified feed into a first stream of purified feed and a bypass stream of purified feed and feeding the first stream of the purified feed to the heat exchanger to undergo cooling therein and feeding the bypass stream of the purified feed to an expander to undergo expansion so that the expanded bypass stream of the purified feed is feedable to the heat exchanger as a cooling medium. The separating of the cooled feed to form the at least one stream of LOX and the at least one stream of oxygen vapor can include feeding the first stream of purified feed from the heat exchanger being fed to a phase separator for forming a first stream of LOX and a first stream of oxygen vapor. The feeding of each stream of the at least one stream of oxygen vapor to the heat exchanger as a cooling medium for cooling the purified feed can includes feeding the first stream of oxygen vapor to the heat exchanger as a cooling medium.
In a twenty-second aspect, embodiments of the process can utilize other process steps by utilization of one or more aspects of the apparatus discussed above or elsewhere herein.
In a twenty-third aspect, the process of the fourteenth aspect can include one or more features of any of the fifteenth aspect, sixteenth aspect, seventeenth aspect, eighteenth aspect, nineteenth aspect, twentieth aspect, twenty-first aspect, and twenty-second aspect. It should therefore be appreciated that other embodiments of the process can include a subset of features of other aspects to provide yet additional embodiments.
It should be appreciated that embodiments of the process and apparatus can utilize various conduit arrangements and process control elements. Various different conduit arrangements and process control systems can be utilized to meet a particular set of design criteria. For instance, embodiments may utilize sensors (e.g., pressure sensors, temperature sensors, flow rate sensors, concentration sensors, etc.), controllers, valves, piping, and other process control elements. Some embodiments can utilize an automated process control system and/or a distributed control system (DCS).
Other details, objects, and advantages of our process for oxygen production, an apparatus for oxygen production, a system for oxygen production, and methods of making and using the same will become apparent as the following description of certain exemplary embodiments thereof proceeds.
Exemplary embodiments of processes for liquid oxygen production, apparatuses for liquid oxygen production, and systems for liquid oxygen production, and methods of making and using the same are shown in the drawings included herewith. It should be understood that like reference characters used in the drawings may identify like components.
It should be understood that
Referring to
In some embodiments, the feed 2 output from the electrolyzer(s) 3 for being fed to the apparatus 1 can include hydrogen (e.g. between 2 volume percent (vol %) hydrogen and 0 vol % hydrogen, less than 2 vol % hydrogen, between 1 vol % hydrogen and 0 vol % hydrogen, etc.) at a concentration that is significantly lower than the concentration of oxygen within the feed 2 and can also include water at a concentration that is significantly lower than the concentration of oxygen within the feed (e.g. The water content for the feed 2 can be in a range of 0.01 vol % and 5 vol % or other suitable range). Other impurities may also be present in the feed 2.
The feed 2 can be at a pre-selected temperature, which can be, for example, an ambient temperature or at a relatively ambient temperature (e.g. a temperature that is below the boiling point of water, a temperature that is less than 90° C. and more than 0° C., a temperature that is less than 90° C., etc.). The feed 2 can also be at an elevated pressure. The pressure of the feed 2 can be at a pre-selected feed pressure of greater than or equal to 5 bara, at least 20 bara, or other suitable elevated pressure range (e.g. a pressure of between 5 bara and 40 bara, etc.).
The apparatus 1 for liquid oxygen production can be configured to process the feed 2 to remove hydrogen, moisture (e.g. water), and/or other impurities from the feed for subsequent liquefaction for the formation of at least one stream of liquid oxygen (e.g. a LOX product stream). The LOX product that is formed can include at least one liquid oxygen product stream, for example. Each LOX product stream can be at least 99 vol % oxygen (e.g. between 99 vol % oxygen and 100 vol % oxygen), or other suitable oxygen concentration range (e.g. at least 99.9 vol % oxygen, between 99.9 vol % oxygen and 99.999 vol % oxygen, between 100 vol % oxygen and 99.9 vol % oxygen, etc.). The LOX product stream can be stored in a storage device 21 (e.g. one or more LOX storage vessels) for subsequent use or transport.
As may best be appreciated from
The purified feed can be fed to the main heat exchanger 7 (Main HX) via a single stream or can be split for providing the purified feed to the main heat exchanger 7 in multiple streams. For instance, the purified feed can be fed from the PPU 5 to the main heat exchanger 7 as a first stream of purified feed 4 or can be split and fed to the main heat exchanger as a first stream of purified feed 4 and a second stream of purified feed 6. The first stream of purified feed 4 can also be referred to herein as a first purified feed stream and the second stream of purified feed 6 can also be referred to herein as a second purified feed stream.
One or more feed conduits can be positioned between the PPU 5 and the main heat exchanger 7 to feed each purified feed stream from the PPU 5 to the main heat exchanger 7. The main heat exchanger 7 can be configured and positioned to cool the one or more purified feed streams for feeding to one or more phase separators 11 and/or expanders 9. For instance, the first stream of purified feed 4 can be fed to the main heat exchanger 7 to undergo go cooling therein from a first pre-selected feed temperature that is within a pre-selected feed temperature range to a second pre-selected temperature that is within a pre-selected liquefaction processing temperature range.
An example of such a pre-selected liquefaction processing range can be −50° C. to −150° C., less than or equal to −50° C., or other suitable temperature range. An example of a first pre-selected feed temperature that is within a pre-selected feed temperature range can be a relatively ambient temperature or a temperature that is less than 100° C. and greater than 0° C. For example, the first pre-selected feed temperature can be a temperature that is between 5° C. and 40° C.
The first purified feed stream that is cooled can be output from the main heat exchanger 7 as a first cooled purified feed stream 8 and be fed to a first expander 9. A first expander feed conduit can be positioned between the main heat exchanger 7 and the first expander 9 to facilitate the flow of the first cooled purified feed stream 8 from the main heat exchanger 7 to the first expander 9.
The location at which the inlet for the first expander feed conduit is positioned at the main heat exchanger 7 can be adapted to meet a particular set of design criteria. For example, the first expander feed conduit can be positioned to receive the first cooled purified feed stream 8 at an end of the main heat exchanger or at a suitable intermediate position between the warm input end and the cold output end of the main heat exchanger 7.
The first expander 9 can be positioned and configured to expand the first cooled purified feed stream 8 to output a reduced pressure and further cooled first purified feed stream 10 for feeding to a first phase separator 11 (PS). The further cooled first purified feed stream 10 can include only oxygen gas or can include a mixture of oxygen gas and oxygen liquid due to the cooling that can occur via expansion. The amount of liquid within the further cooled first purified feed stream 10 can range from 0% liquid to 20% liquid in some arrangements. Other arrangements may utilize different splits between liquid oxygen and gaseous oxygen within the further cooled first purified feed stream 10 output from the first expander 9 (e.g. between 1% and 3% liquid and between 99% and 97% gas, between 3% and 10% liquid and between 97% and 90% gas, between 8% liquid and 15% liquid and between 92% and 85% gas, between greater than or equal to 0% liquid and 1% liquid and less than or equal to 100% gas and 99% gas, etc.).
In some embodiments, the further cooled first purified feed stream 10 that is output from the first expander 9 can be routed directly to the main heat exchanger 7 as a cooling medium to provide cooling therein prior to being vented as a waste stream 16.
In other embodiments, the further cooled first purified feed stream 10 can be fed from the first expander 9 to the first phase separator 11. For example, the first phase separator (PS) can be connected to the first expander 9 via a first phase separator feed conduit positioned between the first phase separator 11 and the first expander 9 for the first phase separator 11 to receive the further cooled first purified feed stream 10 from the first expander 9. The first phase separator 11 can separate the further cooled first purified feed stream 10 to form a first oxygen gas stream 14 for outputting to the main heat exchanger 7 and also form a first liquid oxygen stream for outputting as a first LOX stream 12 for providing to LOX storage 21 (e.g. one or more vessels for LOX storage) or to a second phase separator as shown by broken line arrow 12a to form a first LOX stream 12 for sending to LOX storage 21. The stored LOX can be subsequently used in another plant process or provided for transport for use by one or more end users or customers.
The first LOX stream 12 can be fed from the first phase separator 11 to the LOX storage 21 via a first storage conduit positioned between the first phase separator 11 and the LOX storage. The first phase separator 11 can also be connected to the main heat exchanger 7 so that the first oxygen gas stream 14 that is formed via the first phase separator 11 can be fed to the main heat exchanger 7 to function as a cooling medium therein for cooling of the one or more purified feed streams fed to the main heat exchanger 7. The first oxygen gas stream 14 can subsequently be vented as waste as a waste stream 16. Prior to venting, the warmed oxygen gas stream can be utilized for regeneration of one or more beds of adsorbent material within one or more adsorbers of the PPU in some embodiments.
In some implementations, the first oxygen gas stream 14 can undergo further expansion prior to being vented as a waste stream. In such an implementation, the first oxygen gas steam can be at a pressure that is greater than ambient pressure so that the first oxygen gas stream 14 can undergo additional expansion. For example, the first oxygen gas stream 14 can be passed through the main heat exchanger 7 to undergo warming as a cooling medium therein and subsequently be output from the main heat exchanger as a second expander feed stream 14a for being fed to a second expander 9 for undergoing expansion therein for being output as a cooled, expanded cooling medium stream 14b that can be fed to the main heat exchanger 7 for providing additional cooling therein before being output as a waste stream 14c from the main heat exchanger for being vented as a waste stream 16.
A second expander feed conduit can be positioned between the main heat exchanger 7 and the second expander 9 for feeding of the warmed first oxygen gas stream 14 to the second expander 9 as the second expander feed stream 14a. The location at which the warmed first oxygen gas stream 14 is output from the main heat exchanger 7 for feeding to the second expander as the second expander feed stream 14a can be a location at which the oxygen gas stream is at its warmest temperature after having passed through the heat exchanger 7 or can be another suitable intermediate location that can be considered suitable for feeding the gas to the second expander 9. A second expander output conduit can be positioned between the second expander 9 and the main heat exchanger 7 to feed the cooled and expanded oxygen gas back to the main heat exchanger 7 as the cooling medium stream 14b. The second expander output conduit can be positioned and configured so that the cooling medium stream 14b is fed to an intermediate section of the main heat exchanger 7 to pass through a portion of the main heat exchanger for providing additional cooling therein. The particular feed location for the cooling medium stream 14b at the main heat exchanger 7 can be selected based on the temperature of that stream and the cooling that the cooling medium stream 14b is to provide in the main heat exchanger for cooling of the one or more purified feed streams.
In implementations that include split purified feed streams, a second stream of purified feed 6 can also be fed to the main heat exchanger 7 via a second purified feed conduit positioned between the PPU 5 and the main heat exchanger 7. Alternatively, the second stream of purified feed 6 can be split from the first stream of purified feed 4 within the main heat exchanger 7 after this first stream is fed to the main heat exchanger 7. The second stream of purified feed 6 can be output from the main heat exchanger 7 as a second cooled purified stream 6a for being fed to a second phase separator 11 (PS) or for being fed to the first phase separator 11 as a second phase separator feed 6d that can be fed to the first phase separator so that a portion of the purified feed that is fed to the first phase separator bypasses the first expander 9 (see e.g. example implementations shown in
In implementations that utilize the second phase separator 11, the second phase separator 11 can be positioned to receive the second cooled purified feed stream 6a via a second phase separator feed conduit positioned between the second phase separator 11 and the main heat exchanger 7. The second phase separator 11 can form a second oxygen gas stream 6c and a second liquid oxygen stream 6b. The second liquid oxygen gas stream 6b can be output for feeding to LOX storage 21 via an LOX storage feed conduit positioned between the second phase separator 11 and the LOX storage 21. The second liquid oxygen gas stream 6b can be fed separately to LOX storage via a separate conduit or can be fed for mixing with the first LOX stream 12 for providing to LOX storage 21. If mixing with first LOX stream 12 occurs, one or more valves can be positioned in the conduit(s) to account for pressure differentials to facilitate the feeding of the liquid oxygen streams to LOX storage 21. The second oxygen gas stream 6c can be fed to the main heat exchanger 7 as a second cooling medium for cooling of the purified feed streams fed to the main heat exchanger 7. The warmed second oxygen gas stream 6c can be output from the main heat exchanger as a waste stream 16 for venting to atmosphere. Prior to venting, the warmed oxygen gas can be utilized for regeneration of one or more beds of adsorbent material within one or more adsorbers of the PPU in some embodiments.
One or more companders 15 can be utilized in embodiments to increase the pressure of the purified feed or feed prior to the purified feed being fed to the main heat exchanger 7. Each compander can include at least one compressor stage C that is linked to a different expander. For instance, a first compander 15 can include at least one first compressor stage C that is linked to the first expander 9 via an interconnection 17 so that expansion of gas provided by the first expander 9 provides power for the compression of the at least one first compressor stage C of the first compander 15. It should be appreciated that the first compander 15 includes the at least one first compressor stage C and the first expander 9 interconnected to the at least one first compressor stage in such an arrangement.
A second compander 15 can also be utilized in some implementations that may utilize multiple companders 15. The second compander 15, when utilized, can include at least one second compressor stage C that is linked to the second expander 9 via an interconnection 17 so that expansion of gas provided by the second expander 9 provides power for the compression of the at least one second compressor stage C of the second compander 15. It should be appreciated that the second compander 15 includes the at least one second compressor stage C and the second expander 9 interconnected to the at least one first compressor stage in such an arrangement. In some implementations, the second compander 15 can be positioned in series with the first compander 15 for compression of a first stream of purified feed 4 (e.g. exemplary implementation shown in
In other implementations, the first compander 15 can be positioned for compression of the first stream of purified feed 4 and the second compander 15 can be positioned for compression of the second stream of purified feed 6 (e.g., exemplary implementation of
In some implementations, it is contemplated that only the second compander 15 may be utilized (e.g. a compander including an interconnection 17 with the second expander 9 may be utilized, but the first compander including an interconnection 17 with the first expander 9 may not also be used). In such an implementation, the second compander 15 can be considered a first compander as it may be the only compander in the apparatus 1.
In some implementations, the first stream of purified feed 4 can also be split to include a bypass stream 4bp portion of the purified feed that can be fed to a second expander 9 to cool that portion of the feed via expansion and subsequently feed the cooled bypass stream portion to the main heat exchanger 7 to function as a cooling medium therein. At least one compander 15 can also be included in such an implementation for compression of this bypass stream 4bp portion of the purified feed stream before the bypass stream 4bp is fed to the expander 9 and before that stream is fed to the main heat exchanger 7. In some embodiments, the bypass stream 4bp can be passed through main heat exchanger 7 to be cooled before discharging to the inlet of the second expander 9.
A compression stage C of at least one compander 15 of the bypass stream can be linked or interconnected to the second expander 9 or first expander in some embodiments. This type of arrangement may be utilized when additional cooling duty from the purified feed stream may be utilized in the main heat exchanger 7 to suitably cool the purified feed portion that is to be used for forming at least one LOX product stream for feeding to LOX storage 21 while also permitting no other cooling medium source to be used for cooling and formation of the at least one LOX stream for feeding to LOX storage 21.
As may be appreciated from
As can be appreciated from
As can be appreciated from
As noted above, the second expander feed conduit can be positioned between the main heat exchanger 7 and the second expander 9 for feeding of the warmed first oxygen gas stream 14 to the second expander 9 as the second expander feed stream 14a. The location of the inlet for this feed conduit can be any suitable location (e.g. near warm end of the main heat exchanger or at the warm end of the main heat exchanger 7, etc.). For example, the warmed first oxygen gas stream 14 can be fed to the second expander 9 after being output from the hot end of the main heat exchanger 7 when the warmed first oxygen gas stream 14 is at its warmest temperature after being passed through the main heat exchanger 7 or from another location that may be considered suitable for feeding to the second expander 9. The second expander output conduit can be positioned between the second expander 9 and the main heat exchanger 7 to feed the cooled and expanded oxygen gas back to the main heat exchanger 7 as the cooling medium stream 14b. The second expander output conduit can be positioned and configured so that the cooling medium stream 14b is fed to an intermediate section of the main heat exchanger 7 to pass through a portion of the main heat exchanger for providing additional cooling therein. The particular feed location for the cooling medium stream 14b at the main heat exchanger 7 can be selected based on the temperature of that stream and the cooling that the cooling medium stream 14b is to provide in the main heat exchanger for cooling of the one or more purified feed streams.
Referring to
The second compander 15 can include an interconnection 17 between the at least one second compressor stage C of the second compander and the second expander 9 of the second compander 15. The interconnection can be arranged and configured so that the expansion of gas provided by the second expander 9 powers or helps power compression of the purified feed provided by the at least one second compression stage C of the second compander 15.
Referring to
The second compander 15 can include an interconnection 17 between the at least one second compressor stage C of the second compander 15 and the second expander 9 of the second compander 15. The interconnection 17 can be arranged and configured so that the expansion of gas provided by the second expander 9 powers or helps power compression of the purified feed provided by the at least one second compression stage C of the second compander 15.
In the implementation of
As noted above, the second expander feed conduit for the implementation of
The bypass stream 4bp can include one or more companders 15 (e.g. as shown in broken line in
The cooling provided by the expanded bypass stream 4bp fed to the main heat exchanger as a cooled, expanded cooling medium stream 14b can help cool the portion of the purified feed that is to undergo processing for formation of LOX. This can provide an additional source of cooling in addition to one or more oxygen gas streams that may be provided by one or more phase separators so that no other cooling medium source is needed for the cooling provided by the apparatus 1. This can help permit the apparatus 1 to be utilized without use of other process streams for functioning as a cooling medium in the main heat exchanger 7, for example.
It should be appreciated from
It should be appreciated that other implementations can also utilize a second stream of purified feed 6 that can be split from the first stream of purified feed 4 either upstream of the heat exchanger 7 or within the heat exchanger 7 as well for feeding to a second phase separator for formation of a second stream of LOX (e.g. as shown in
Embodiments of the apparatus 1 can be configured to provide a relatively low yield recovery of the oxygen gas as LOX when compared to an oxygen recycle liquefier or a liquid nitrogen/LOX exchange paired with a recycle liquefier with a different working fluid (e.g. nitrogen). For example, the exemplary implementation shown in
It should be appreciated that the embodiments of the apparatus 1 for liquid oxygen production can be arranged and configured for an open loop configuration that can avoid recycling of the oxygen gas to improve the recovery yield of the process. This open loop process can be provided to avoid use of any feed compression (e.g. example implementations of
The low oxygen yield provided by the open loop embodiments of the apparatus 1 can be implemented to help reduce waste and further improve the efficiency and operation of hydrogen production processes that utilize one or more electrolyzers 3. Such processes can help provide improved opportunities for non-carbon dioxide producing systems used for formation of hydrogen (e.g., green hydrogen production processes) which can help provide an improvement in environmental operation of hydrogen production systems while also permitting an additional liquid oxygen product to be formed and reducing waste to be vented from operation of such systems.
Additionally, we have determined that embodiments can provide an improvement in safety. An oxygen gas feed compressor and/or recycle compressor can include an inherent safety risk (e.g., fire or an explosion) as noted above. Avoidance of any type of compression that can be provided by some embodiments of the apparatus 1 (e.g. exemplary implementations shown in
Embodiments of the apparatus 1 can also be configured so that there is no need for any other flows of fluid for use of the system beyond the feed 2 provided by the electrolyzer(s) 3 (e.g. can be positioned and configured as a closed processing system). For instance, embodiments can be provided that do not need any cryogenic fluid or a cooling medium from another plant or source beyond the feed 2 to facilitate liquefaction of the oxygen into LOX. Instead, the oxygen vapor from phase separation can be utilized as the only cooling medium used in the main heat exchanger. The combination of expansion and use of the expanded oxygen gas vapor for cooling and liquefaction helps avoid use of other cooling medium fluids and can permit embodiments of the apparatus 1 to be more effectively incorporated into a plant via a retrofit operation, for example, and have a simpler arrangement that may need a smaller overall footprint.
It should be appreciated that embodiments of the apparatus 1 for liquid oxygen production can be arranged to practice an exemplary embodiment of a process for liquid oxygen production. An example of such an exemplary embodiment of the process is shown in
As can be appreciated from
In a second step S2, the purified feed can be cooled via a main heat exchanger and/or at least one expander. Each expander that can be utilized for expansion can be a turboexpander, a valve, or other type of expander. In some arrangements utilizing multiple expanders, some expanders can be configured as a turboexpander and others can be configured as a valve, for example. In other implementations, all the expanders can be the same type of expander or all of the expanders may be different types of expanders.
In a third step S3, one or more (or all) of the cooled purified feed stream(s) can undergo phase separation to form at least one liquid oxygen (LOX) stream and at least one oxygen vapor stream. Each LOX stream can be fed to storage while each oxygen vapor stream can be fed to the main heat exchanger as a cooling medium for the heat exchanger.
In situations where one LOX stream may be at a higher pressure than another LOX stream, an LOX stream can undergo pressure adjustment via a valve or being fed to another unit (e.g. LOX output from a first phase separator can be fed to a second phase separator, etc.) to facilitate merging of the formed LOX for feeding to LOX storage 21.
In an optional fourth step S4, a portion of the oxygen vapor can be output from the main heat exchanger as a warmed oxygen vapor flow for feeding to another expander to undergo additional cooling via expansion of that gas. The expanded gas output from that expander can then be fed back to the main heat exchanger as a cooling medium.
In another optional step, S1′, at least a portion of the purified feed can undergo compression via at least one compression stage of at least one compander that is interconnected to an expander so expansion provided by the linked expander of the compander can help power compression provided by the at least one compression stage of the compander that is linked to the expander. The portion(s) of the purified feed can undergo such compression prior to undergoing cooling via the main heat exchanger 7 and/or expansion, for example.
Embodiments of the process shown in
It should be appreciated that modifications to the embodiments explicitly shown and discussed herein can be made to meet a particular set of design objectives or a particular set of design criteria. For instance, the arrangement of valves, piping, and other conduit elements (e.g., conduit connection mechanisms, tubing, seals, valves, etc.) for interconnecting different units of the apparatus for fluid communication of the flows of fluid between different elements (e.g., pumps, heat exchangers, cooling devices, chillers, compressors, etc.) can be arranged to meet a particular plant layout design that accounts for available area of the plant, sized equipment of the plant, and other design considerations. As another example, the flow rate, pressure, and temperature of the fluid passed through the various apparatus or system elements can vary to account for different design configurations and other design criteria.
Embodiments of the apparatus for liquid oxygen production, process for liquid oxygen production, and/or system for liquid oxygen production can each be configured to include process control elements positioned and configured to monitor and control operations (e.g., temperature and pressure sensors, flow sensors, an automated process control system having at least one work station that includes a processor, non-transitory memory and at least one transceiver for communications with the sensor elements, valves, and controllers for providing a user interface for an automated process control system that may be run at the work station and/or another computer device of the plant, etc.). It should be appreciated that embodiments can utilize a distributed control system (DCS) for implementation of one or more processes and/or controlling operations of an apparatus as well.
As another example, it is contemplated that a particular feature described, either individually or as part of an embodiment, can be combined with other individually described features, or parts of other embodiments. The elements and acts of the various embodiments described herein can therefore be combined to provide further embodiments. Thus, while certain exemplary embodiments of the process, apparatus, system, and methods of making and using the same have been shown and described above, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims.
