Patent Application
20230147955
The present disclosure relates generally to systems and methods for liquefying hydrogen and, more particularly, to a system and method that liquefies hydrogen and uses hydrogen gas storage as a refrigerant source.
Industrial gases, such as natural gas or hydrogen, are advantageously stored or transported in a liquid state because they occupy a much smaller volume (natural gas for instance is 1/600th the gaseous state). The liquefied gases are then vaporized back to a gaseous state for use at a site or system.
Gaseous hydrogen is converted to liquefied hydrogen by cooling it to at least about −253° C. The typical process of cooling utilizes a high amount of energy and can be very expensive with regard to equipment costs. The process may include multiple refrigeration cycles and involve multiple stages of gas compression.
The use of letdown energy from high-pressure gases to provide refrigeration and reduce operating costs in a hydrogen liquefaction system is illustrated in U.S. Pat. No. 10,634,425 to Guillard et al. The '425 patent uses letdown energy from high-pressure gases other than hydrogen to provide cooling in the warm end of the system and a methanol production unit as a source of a high-pressure hydrogen rich purge gas for letdown refrigeration energy to provide cooling in the cold end of the system. After use to provide cooling, the hydrogen rich stream is sent back to the methanol plant as low pressure fuel.
It is desirable to provide a hydrogen liquefaction system and method which lowers operational and equipment costs in at least some applications.
There are several aspects of the present subject matter which may be embodied separately or together in the methods, devices and systems described and claimed below. These aspects may be employed alone or in combination with other aspects of the subject matter described herein, and the description of these aspects together is not intended to preclude the use of these aspects separately or the claiming of such aspects separately or in different combinations as set forth in the claims appended hereto.
In one aspect, a system for liquefying a hydrogen gas feed stream includes a cold box feed line configured to receive a cold box feed stream having a cold box feed stream pressure where the cold box feed stream includes at least the hydrogen gas feed stream. A heat exchanger system has a liquefier cooling passage in fluid communication with the cold box feed line and is configured to receive and cool a liquefier stream so that a product stream is formed. A product expansion device is in fluid communication with an outlet of the liquefier cooling passage and is configured to receive the product stream so that an expanded product stream is formed.
The heat exchanger system includes a refrigerant cooling passage configured to receive a refrigerant feed stream so that a cooled refrigerant feed stream is formed. A refrigerant expansion device is in fluid communication with the refrigerant cooling passage of the heat exchanger system so that an expanded refrigerant stream is formed. The heat exchanger system includes a refrigerant warming passage in fluid communication with an outlet of the refrigerant expansion device so that cooling is provided in the heat exchanger system.
The heat exchanger system includes a first hydrogen high-pressure refrigerant cooling passage configured to receive and cool a high-pressure hydrogen supplemental refrigerant feed stream so that a cooled hydrogen supplemental refrigerant stream is formed. A supplemental refrigerant expansion device has an inlet in fluid communication with the first hydrogen high-pressure refrigeration cooling passage so that an expanded hydrogen supplemental refrigerant stream is produced having a pressure not lower than the cold box feed stream pressure. The heat exchanger system includes a high-pressure hydrogen refrigerant warming passage in fluid communication with an outlet of the supplemental refrigerant expansion device and is configured to receive the expanded hydrogen supplemental refrigerant stream so that cooling is provided in the heat exchanger system and a high-pressure hydrogen product stream is formed that is at a pressure higher than the cold box feed stream pressure.
In another aspect, a method for liquefying a hydrogen gas feed stream includes the steps of: receiving a cold box feed stream including at least the hydrogen gas feed stream into a heat exchanger system, where the cold box feed stream has a cold box feed stream pressure; cooling a liquefier feed stream that includes the cold box feed stream in a heat exchanger system to form a product stream; expanding the product stream to form an expanded product stream; cooling a refrigerant stream in the heat exchanger system to form a cooled refrigerant stream; expanding the cooled refrigerant stream to form a first expanded refrigerant stream; warming the first expanded refrigerant stream so that cooling is provided in the heat exchanger system; cooling a high-pressure hydrogen supplemental refrigerant feed stream in the heat exchanger system so that a cooled hydrogen supplemental refrigerant stream is formed; expanding the cooled hydrogen supplemental refrigerant stream to form an expanded hydrogen supplemental refrigerant stream having a pressure not lower than the cold box feed stream pressure; and warming the expanded supplemental hydrogen refrigerant stream so that cooling is provided in the heat exchanger system and a high-pressure hydrogen product stream is formed that is at a pressure higher than the cold box feed stream pressure.
In accordance with the present disclosure, hydrogen gas from high-pressure storage(s), such as a hydrogen storage cavern, high-pressure cylinders, hydrogen pipeline, and/or other high-pressure storage or components, is used to provide refrigeration to a hydrogen liquefaction system. The high-pressure hydrogen then exits the system as a hydrogen stream that can be utilized by different systems and/or processes. Usage of a stored high-pressure hydrogen gas source, including the letdown energy provided by such a source, eliminates or greatly reduces the refrigeration requirement from other sources, reducing power required and operating cost.
A process flow diagram and schematic illustrating an embodiment of the hydrogen liquefaction system of the current disclosure is provided in
It should be noted herein that the lines, conduits, piping, passages and similar structures and the corresponding streams are sometimes both referred to by the same element number set out in the figures. Also, as used herein, and as known in the art, a heat exchanger is that device or an area in the device wherein indirect heat exchange occurs between two or more streams at different temperatures, or between a stream and the environment. In addition, all heat exchangers referenced herein may be incorporated into one or more heat exchanger devices or may each be individual heat exchanger devices. As used herein, the terms “communication”, “communicating”, and the like generally refer to fluid communication unless otherwise specified. And although two fluids in communication may exchange heat upon mixing, such an exchange would not be considered to be the same as heat exchange in a heat exchanger, although such an exchange can take place in a heat exchanger. A heat exchange system or a heat exchanger system can include those items though not specifically described are generally known in the art to be part of a heat exchanger, such as expansion devices, flash valves, and the like. As used herein, the terms, “high”, “middle”, “warm”, “cold” and the like are relative to comparable streams, as is customary in the art.
With reference to the embodiment of
The hydrogen cold box feed stream 4 may have a pressure of about 200-600 psig, and preferably 250-400 psig. The first and second hydrogen compressors 101 and 102 can each consist of a single compressor or compressor stage or more than one compressor or compressor stage. Alternatively, the compressors 101 and 102 can represent stages of the same compressor with at least one interstage feed. If the pressure of the hydrogen feed 3 is high enough to feed the cold box, compression of that stream is not necessary, and it can be combined with the recycle streams downstream of the second compressor 102, as indicated in phantom at 130 in
The hydrogen cold box feed 4 is cooled in a first heat exchanger 103 to about 80° K to form a first adsorber feed steam 5 that is fed to a first adsorber system 104 that removes trace impurities to prevent freezing of impurities and subsequent plugging of a heat exchanger passage. The first adsorber system 104 shown in
The stream exiting the first adsorber is split or divided into a liquefier feed stream 6 and a hydrogen refrigerant stream 7. Preferably approximately 20% of the stream will become the liquefier feed 6 and the remainder will become the hydrogen refrigerant 7.
The liquefier feed 6 is cooled further in a second heat exchanger 106 that contains a second heat exchanger catalyst passage 107 that contains ortho-para conversion catalyst. The ortho-para conversion catalyst converts a portion of the ortho-hydrogen to para-hydrogen in the liquefaction process to minimize volatilization of the liquid product. Alternatively, one or more catalytic reactors outside of the heat exchangers can be used. Suitable catalysts, such as iron oxide, chromium oxide, or vanadium oxide, are well known in the art.
The liquefier feed 6 exits the second heat exchanger 106 as a cooled liquefier feed stream 8. The cooled liquefier feed 8 is cooled further in a third heat exchanger 109, a fourth heat exchanger 112 and a fifth heat exchanger 116 containing a third heat exchanger catalyst passage 110, a fourth heat exchanger catalyst passage 113, and a fifth heat exchanger catalyst passage 117, respectively, to produce a cold high-pressure hydrogen stream 11. Alternatively, one or more catalytic reactors outside of the heat exchangers can be used in place of catalysts within heat exchanger passages 110, 113 and/or 117.
A single heat exchanger or more than three heat exchangers may be substituted for the third through fifth heat exchangers (109, 112 and 116) in alternative embodiments of the system. Indeed, a single heat exchanger or a heat exchanger system may be substituted for, or may incorporate any or all of, the first through fifth heat exchangers (103, 106, 109, 112 and/or 116).
The cold high-pressure hydrogen stream 11 is expanded across a product expansion device 118 to further cool it and produce a mixed-phase product stream or two-phase hydrogen stream 12 that is fed to a hydrogen product separator 119. The product expansion device 118, as in the case of any of the expansion devices or valves disclosed in
A liquid hydrogen product stream 13 exits the bottom of the hydrogen product separator 119 while a saturated hydrogen vapor stream 14 exits the top. The saturated hydrogen vapor stream 14 is warmed in the fifth heat exchanger 116, where it provides refrigeration to assist in the production of the cold high-pressure hydrogen stream 11, and exits as a warmed hydrogen vapor stream 15.
The hydrogen refrigerant 7 is cooled in the second heat exchanger 106 and the third heat exchanger 109 to produce cooled hydrogen refrigerant streams 16 and 17, respectively. A first portion 18 of the cooled hydrogen refrigerant stream 17 is cooled further in the fourth heat exchanger 112 to produce a cold high-pressure hydrogen refrigerant stream 20 while the remainder or second portion 19 of the cooled hydrogen refrigerant 17 is fed to a cold expansion device, such as cold expansion turbine 111, where it is expanded to a lower pressure and exits at a lower temperature as a cold turbine product 29.
The cold high-pressure hydrogen refrigerant stream 20 is expanded across a refrigerant expansion device 114 to further cool it and produce a mixed-phase or two-phase hydrogen refrigerant stream 21 that is fed to a hydrogen refrigerant separator 115. A liquid hydrogen refrigerant stream 22 exits the bottom of the hydrogen refrigerant separator 115 and is fed to the fifth heat exchanger 116 where much of it is vaporized to provide refrigeration to the fifth heat exchanger 116 and exits as a mixed-phase hydrogen refrigerant stream 23 that is fed to the hydrogen refrigerant separator 115.
The hydrogen refrigerant vapor stream 24 exiting the hydrogen refrigerant separator 115 combines with the warmed hydrogen vapor 15 to form a cold low-pressure hydrogen refrigerant stream 25. The cold low-pressure hydrogen refrigerant stream 25 and the cold turbine product stream 29 are heated in the fourth heat exchanger 112 and the third heat exchanger 109 to form a warm low-pressure hydrogen refrigerant stream 27 and a warm turbine product 31. The warm low-pressure hydrogen refrigerant stream 27 is heated further in the second heat exchanger 106 and the first heat exchanger 103 to form the low-pressure hydrogen recycle stream 1. The warm turbine product stream 31 is heated further in the first heat exchanger 103 to form the medium-pressure hydrogen recycle stream 2.
A high-pressure hydrogen supplemental refrigeration feed stream 41 at a pressure higher than about 600 psig, typically about 1000-2000 psig, is cooled in the first heat exchanger 103 and fed as stream 42 to a second adsorber system 105 operating at a higher pressure and similar temperature to the first adsorber system 104 to form a purified high-pressure hydrogen stream 43 that is cooled further in the second heat exchanger 106 to form a warm expansion turbine feed 44 that is fed to a warm expansion device, such as warm expansion turbine 108. The warm expansion turbine 108 operates at a higher temperature, a higher inlet pressure, and a higher outlet pressure than the cold expansion turbine 111 and forms a warm expansion turbine product 45, which is at a higher pressure than the hydrogen cold box feed 4 pressure. The warm expansion turbine product 45 is heated in the third heat exchanger 109 and the first heat exchanger 103 forming a high-pressure hydrogen product 47 that is at a pressure lower than the high-pressure stored hydrogen feed 41 but higher than the hydrogen cold box feed 4 pressure. The high-pressure hydrogen product 47 can be fed to a gas turbine, a chemical process, a pipeline, an energy production process, hydrogen storage, or other application. Alternatively, the high-pressure hydrogen product 47 may be fed to a gas turbine that is used to power compressor stages or compressors 101 and/or 102.
Additional refrigeration may be provided to the process using an external refrigerant, such as liquid or gaseous nitrogen. A second heat exchanger refrigerant stream 51, such as liquid nitrogen or another refrigeration source, is heated in the second heat exchanger 106 and/or the first heat exchanger 103, to provide additional cooling. A first heat exchanger refrigerant stream 54, such as cold gaseous nitrogen or another refrigeration source, is heated in the first heat exchanger 103 to provide additional cooling.
As noted previously, heat exchangers 103, 106, 109, 112 and 116 could be incorporated into a heat exchanger system. Such a heat exchanger system may include, as examples only, a single heat exchanger, separate heat exchangers (as illustrated in
In an alternative embodiment, a portion of the high-pressure hydrogen product 47 can be used as the cold box feed 4, as illustrated in phantom at 132 in
In another alternative embodiment, a portion of the warm expansion turbine product stream 45 can be cooled further and expanded in either a valve or expander to provide additional refrigeration in heat exchangers 109 and/or 106 and/or 103 as stream 45 is already cold and available at high pressure.
The embodiments of the system and process of the disclosure presented above therefore take advantage of the energy stored in a high-pressure storage system such as a hydrogen cavern, pipeline, stationary storage system or other high pressure hydrogen storage to provide refrigeration for a liquefaction system, increasing system efficiency and saving equipment and/or operating costs. The hydrogen product (47 in
As noted previously, the hydrogen stream 5 entering the first adsorber 104 of
In addition, the embodiment of
Even if the recovered hydrogen (stream 47) is not at a higher pressure than the cold box feed 4, using the outlet hydrogen somewhere other than recycling it back to the liquefier may also be useful.
The following example provides more information on one configuration of the invention. It is not intended to limit the disclosed invention or the scope of the disclosure. In the embodiment of
The first heat exchanger 103 in this embodiment decreases the temperature of the stream to 81 K. Trace impurities are removed in the first adsorber system 104 and the stream is split into the liquefier feed 6 (1000 lbmol/hr) and the hydrogen refrigerant stream 7 (3886 lbmol/hr). This results in a split of 20-21% of the feed stream sent to the liquefier, which is higher than conventional hydrogen liquefiers known in the art. The liquefier feed 6 is cooled from 81 K to produce the cold high-pressure hydrogen stream 11 at 22 K in the heat exchangers 106, 109, 112, and 116. This stream is expanded to 45 psia in the product expansion device 118 to form the liquid hydrogen product stream 13.
The hydrogen refrigerant stream 7 is cooled in heat exchangers 106 and 109 to produce the cooled hydrogen refrigerant stream 17 at 51 K, which is split into a first portion 18 (351 lbmol/hr), which is cooled to 27 K in heat exchanger 112, and a second portion 19 (3553 lbmol/hr), which is fed to the cold expansion turbine 111. The second portion 19 is expanded from 356 psia to 35 psia in the turbine and cooled from 51 K to 24 K. This cold turbine product 29 is used to provide refrigeration in the heat exchangers. The first portion 18 is cooled in heat exchanger 112 to produce the cold high-pressure hydrogen refrigerant stream 20 at 27 K, which is expanded from 356 psia to 18 psia in the refrigerant expansion valve device 114 and cooled from 27 K to 21 K, and partially condensed. The partially condensed stream is mixed with the mixed-phase hydrogen refrigerant stream 23 and separated in the hydrogen refrigerant separator 115 to form the liquid hydrogen refrigerant stream 22 (1170 lbmol/hr) and the hydrogen refrigerant vapor stream 24 (351 lbmol/hr). The liquid hydrogen refrigerant stream is partially vaporized to provide cooling in the coldest heat exchanger 116 and returns to the hydrogen refrigerant separator. The refrigerant vapor stream provides cooling in the other heat exchangers 112, 109, 106, and 103. Additional refrigeration is provided by liquid nitrogen 51 (106 lbmol/hr) and cold nitrogen vapor 54 (961 lbmol/hr).
The high-pressure stored hydrogen feed 41, in this example, feeds 2780 lbmol/hr at 300 K and 2000 psia of normal hydrogen to the heat exchanger system and is cooled to 79 K and fed to the warm expansion turbine 108, where it is expanded to 500 psia and cooled to 55 K. This is a sufficiently low temperature to provide refrigeration to the system and actually replace a standard warm expander of the prior art. Furthermore, the stream is recovered from the cold box at 498 psia as the high-pressure hydrogen product 47. Recovering this stream at a pressure not lower than the cold box feed may provide the combined benefits of recovering a hydrogen stream at high pressure for use outside the liquefier and reducing the refrigeration requirement when compared to conventional hydrogen liquefaction processes.
Conditions and compositions of selected streams for the above Example are shown in Table 1.
In another embodiment, hydrogen refrigerant passes through a series of expanders that operate at different pressures and/or temperatures or is fed to more than one set of expanders in parallel that also operate at different temperatures. In this case, the expander for the hydrogen supplemental refrigeration stream would be added to a standard hydrogen liquefaction process. Although this would represent additional capital cost, operating and power costs may be reduced compared to the standard process known in the art. As hydrogen liquefaction becomes more common, these processes could become larger and the operating cost reduction could justify additional capital cost. The additional higher-temperature hydrogen refrigerant expanders may also increase operating flexibility to adjust for fluctuating pressure in the high-pressure hydrogen storage source. This could be beneficial because hydrogen storage pressures, such as those in caverns or pipelines, fluctuate with varying supply and demand.
In an alternative embodiment, with reference to
In the embodiment of
In contrast to the embodiment of
The primary difference between the two process configurations of
The refrigerant adsorber product steam 74 is cooled further in the heat exchanger system to produce a first 75 and second 76 cooled refrigerant stream. In one embodiment, a portion of the first cooled refrigerant stream 141 is expanded in a first refrigerant expander 140 to produce a first low-pressure refrigerant stream 142, which provides cooling to the heat exchanger system. This expander provides additional refrigeration if the warm expansion turbine 108 does not provide enough refrigeration.
A portion of the second cooled refrigerant stream 77 is expanded in a second refrigerant expander 203 to produce a second low-pressure refrigerant stream 78, which provides cooling to the heat exchanger system. The remainder of the second cooled refrigerant stream 82 is cooled further in the heat exchanger system to produce a cold high-pressure refrigerant stream 83, which is expanded in a third refrigerant expander 204 to produce a third low-pressure refrigerant stream 84, which provides cooling to the heat exchanger system. The third low-pressure refrigerant stream 84 is partially warmed in the heat exchanger system to produce a warm third low-pressure refrigerant 85, which mixes with the second low-pressure refrigerant stream 78 to produce a combined low-pressure refrigerant 86 that is heated to a first 79, second 80, and third 81 warmed refrigerant stream in the heat exchanger system before exiting as the warm low-pressure refrigerant 71.
In one alternative to the configuration shown in
One advantage of the closed-loop refrigeration system is that ortho-para conversion of the cold box feed 4 can begin at a higher temperature. In this case, because the entire stream is being liquefied, it is advantageous to begin ortho-para conversion in the first heat exchanger 103 by packing an ortho-para conversion catalyst 120 into the lower-temperature portion of the cold box feed passage. This allows for conversion of the 75% ortho-hydrogen feed to about 50% ortho-hydrogen before entering the first adsorber system 104.
While the preferred embodiments of the disclosure have been shown and described, it will be apparent to those skilled in the art that changes and modifications may be made therein without departing from the spirit of the disclosure, the scope of which is defined by the following claims.
This application claims the benefit of U.S. Provisional Application No. 63/276,888, filed Nov. 8, 2021, the contents of which are hereby incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| 63276888 | Nov 2021 | US |
