Apparatus and process for limiting thermal stress for heat exchangers

Abstract

An apparatus for heat exchangers can include a mechanism or flow control processing arrangement that can be configured to maintain a temperature profile of the internal components of a heat exchanger within a pre-selected temperature range during periods of non-operation of a plant process or facility to help reduce the thermal stress incurred by the heat exchanger and its internal components. Embodiments of the heat exchanger apparatus and process of heat exchanger operation can facilitate maintenance of a pre-selected temperature profile in a heat exchanger during periods of non-operation or non-use and also facilitate quicker start-up operation when plant processing is to resume with heat exchanger operation.

Description

[0001] The present innovation relates to heat exchanger related processes and heat exchanger related apparatuses.

[0002] Heat exchangers can be utilized in different processes to facilitate cooling and warming of different process fluids. Examples of heat exchangers and heat exchange processing for different types of industrial applications can be appreciated from International Publication Nos. WO 2021 / 037391 and WO 2020 / 200521 as well as European Publication No. EP4246070A1 and Japanese Publication No. JP2022156743A.

[0003] In cryogenic type applications, heat exchangers that may be utilized to cool a feed of compressed gas may have a warm end that is relatively close to ambient temperature (e.g., between 0°C and 40°C) and a cold end that can be in the cryogenic temperature range (e.g., for feeding air to an air separation unit, etc.). For example, the cold end of the heat exchanger may be in a temperature range of -150°C to -195°C. The intermediate portion of the heat exchanger can be at a different temperature between the cold and warm ends (e.g., the fluid passing from the warm end to the cold end gets progressively cooler as the warmer fluid moves to the cooler end and the fluid passing from the cold end to the warm end gets progressively warmer as it passes to the warmer end). Such heat exchangers may be brazed aluminum heat exchangers (BAHX). Large cryogenic plants may manifold several BAHX together.

[0004] In the event the heat exchanger is not in use, processes including heat leak and thermal conduction can cause the heat exchanger internal portions to move to a temperature that differs from the temperature of the internal portions of the heat exchanger during normal operation, such as an average temperature or an ambient temperature. In many operational situations, the average temperature or ambient temperature can differ significantly from the temperature of the internal portions of the heat exchanger during its normal operation, for example. This can create a thermal stress on the heat exchanger's components. For example, when the temperature profile of a heat exchanger changes, the thermal expansion or contraction that can occur can result in significant thermal stress on the components of the heat exchanger. This type of stress can occur when restarting a liquefier of a plant after the temperature profile of the heat exchanger has been allowed to deviate significantly from its operational profile (e.g., was not operating for a significant period of time between the plant being shut down and the plant being restarted).

[0005] In cyclic operation, this thermal stress effect can combine with stress due to pressure cycling to produce an overall cyclic stress on the equipment. In a conventional operational arrangement for a conventional plant, such an operational condition for the heat exchanger may only occur infrequently such that this cyclic stress may not be incurred so often as to be considered problematic in any way. However, we have determined that this type of cyclic stress can be a significant problem in the event the heat exchanger is expected to be utilized in a process that may be turned off and on numerous times in a day or week or month. In such an operational situation, the cyclic stress events may occur hundreds of times per year instead of just 0-5 times per year of operation. Such cyclic stress occurring much more frequently can cause internal components of a heat exchanger to fail from fatigue, which may require extensive repair work or replacement work for the heat exchanger equipment and also result in prolonged down time of a facility to address an unexpected problem.

[0006] To help address such problems, we have developed embodiments of a process for operation of a heat exchanger, a heat exchanger apparatus, and methods of making and using the same that can help avoid or limit thermal stresses that may be experienced by a heat exchanger when a plant is shutdown or non-operational relatively often (e.g., daily, multiple times a week, etc.). Such embodiments can facilitate maintenance of a temperature profile of a heat exchanger to a pre-selected temperature profile via utilization of a single fluid stream or a minimal number of fluid streams to provide the heat transfer that may be needed for maintenance of the temperature profile to within a pre-selected temperature range or pre-selected profile when a liquefier of a plant is not operational. Embodiments can help minimize thermal stress experienced by the heat exchanger and also enable faster restarting of operations that the heat exchanger may support. Embodiments can also be provided in a way so that a relatively small amount of additional equipment may be needed for implementation. These types of features can permit a more flexible approach for operations that can also reduce maintenance costs and help preserve the life of the heat exchanger equipment. Embodiments can also be configured to help permit variable plant operation due to power price fluctuations, weather conditions that may affect availability of renewable power for powering operations, and / or other operational conditions, resulting in improved efficiency, reduced cost, and / or reduced environmental impact.

[0007] In some embodiments, the heat exchanger apparatus can be utilized in conjunction with a high temperature process and the maintenance of a temperature profile of a heat exchanger to a pre-selected temperature profile via utilization of a single fluid stream or a minimal number of fluid streams to provide the heat transfer that may be needed for maintenance of the temperature profile when a plant or a process unit of a plant is not operational to maintain the temperature profile of the heat exchanger to within a pre-selected temperature range or pre-selected profile can be a temperature that is greater than ambient temperature (e.g., a relatively hot temperature).

[0008] In other embodiments, the heat exchanger apparatus can be utilized in conjunction with significantly low temperatures (e.g., cryogenic temperature ranges). The maintenance of a temperature profile of a heat exchanger to a pre-selected temperature profile via utilization of a single fluid stream or a minimal number of fluid streams to provide the heat transfer that may be needed for maintenance of the temperature profile when a plant or a process unit of a plant (e.g., a liquefier) is not operational to maintain the temperature profile of the heat exchanger to within a pre-selected temperature range or pre-selected profile can be a temperature that is lower than ambient temperature (e.g., a relatively cold temperature or a temperature in or near a cryogenic temperature range).

[0009] For instance, in some embodiments, the heat exchanger apparatus can be utilized in conjunction with an air separation unit (ASU) to produce nitrogen, oxygen, and / or argon. Other embodiments may utilize the heat exchanger in conjunction with or as a constituent part of other types of ASU systems or other types of industrial processing or plants, such as, for example, liquefaction units or liquefiers (e.g., liquefaction plants for liquefaction of gases such as hydrogen, oxygen, natural gas, nitrogen, argon, or air) or other types of plants that utilize cryogenic fluids or cryogenic operational conditions.

[0010] In a first aspect, a process for operating a heat exchanger apparatus can be provided. Embodiments of the process can include feeding at least a first feed fluid to a heat exchanger apparatus and feeding at least a first refrigerant fluid to the heat exchanger apparatus while a plant process is operational to cool the first feed fluid and heat the first refrigerant fluid. In response to deactivation of the plant process, the feeding of the first feed fluid to the heat exchanger apparatus and the feeding of the first refrigerant fluid to the heat exchanger apparatus can be ceased and at least one process stream can be fed to the heat exchanger apparatus to maintain a temperature profile of the heat exchanger apparatus while the plant process is deactivated.

[0011] In some embodiments, the process stream(s) that may be fed to the heat exchanger apparatus to maintain a temperature profile of the heat exchanger apparatus can be passed through the heat exchanger apparatus and subsequently recirculated back to the heat exchanger apparatus to mimic a heat transfer that occurs to cool the first feed fluid via the first refrigerant fluid. In other embodiments, the process stream(s) may be passed through the heat exchanger apparatus in a single pass through the heat exchanger apparatus to maintain the temperature profile of the heat exchanger apparatus.

[0012] In a second aspect, the at least one process stream can include a boiloff vapor of cryogenic liquid fluid stored in at least one storage tank or a separator boiloff vapor.

[0013] In a third aspect, the process can also include other steps. For example, the process can also include outputting the at least one process stream from the heat exchanger apparatus while a liquefier of the plant process is deactivated and recirculating the output at least one process stream back to the heat exchanger apparatus. As another example, the process can include outputting the at least one process stream from the heat exchanger apparatus while a liquefier of the plant process is deactivated, heating the at least one process stream after it is output from the heat exchanger apparatus, and recirculating the output at least one process stream back to the heat exchanger apparatus as at least one recirculated process stream. In some embodiments, the process can also include outputting the at least one recirculated process stream from the heat exchanger apparatus to vent the recirculated process stream.

[0014] In some embodiments, the recirculated process stream (or gas) can have a temperature of between 0°C and 50°C when it is returned to the heat exchanger apparatus. In other embodiments, the recirculated process stream (or gas) can have another suitable temperature.

[0015] In a fourth aspect, the at least one process stream can include a refrigerant process stream that is at a temperature of between -150°C and -200°C. In other embodiments, the process stream(s) can be at another suitable temperature.

[0016] In a fifth aspect, the first feed fluid can be comprised of nitrogen and / or oxygen. For example, the first feed fluid can be air, can include air, can include a mostly nitrogen stream, can include a stream that includes a significant amount of nitrogen and oxygen, can be a stream that includes a significant amount of oxygen, or can be a stream that is mostly oxygen or mostly nitrogen.

[0017] In a sixth aspect, the first feed fluid can be at a temperature of between 0°C and 50°C and the first refrigerant fluid can be at a temperature of between -150°C and -200°C. In other embodiments, the feed and the refrigerant fluids can be at different temperatures.

[0018] In a seventh aspect, the process can also include adjusting valves to feed the at least one process stream to the heat exchanger apparatus to maintain the temperature profile of the heat exchanger apparatus while a liquefier of the plant process is deactivated. In some embodiments, the at least one process stream can include a boiloff vapor of cryogenic liquid fluid stored in at least one storage tank, a stream output from a column assembly of an air separation unit (ASU), and / or a separator boiloff gas.

[0019] In an eighth aspect, the process of the first aspect can include one or more other features or elements. For example, the process of the first aspect can include one or more features of the second aspect, third aspect, fourth aspect, fifth aspect, sixth aspect, and / or seventh aspect. Embodiments can also include other features or elements. Examples of other features or elements can be appreciated from the exemplary embodiments of the process discussed herein, for instance.

[0020] In a ninth aspect, a heat exchanger apparatus is provided. Some embodiments of the heat exchanger apparatus can be configured to implement an embodiment of the process for operating a heat exchanger apparatus. Embodiments of the heat exchanger apparatus can include a first heat exchanger fluidly connectable to at least a first warm fluid feed conduit and a first refrigerant feed conduit such that a refrigerant is feedable to the heat exchanger apparatus via the first refrigerant feed conduit to cool a feed fluid fed to the heat exchanger apparatus via the first warm fluid feed conduit while a plant process to which the heat exchanger apparatus is utilized is operational. The heat exchanger apparatus can also include a recirculation conduit arrangement positioned to recirculate a process stream passed into the first heat exchanger via the first refrigerant feed conduit while the plant process is shutdown to maintain a temperature profile of the heat exchanger apparatus while the plant process is shutdown.

[0021] In a tenth aspect, the recirculation conduit arrangement comprises a temperature difference control device. In some embodiments, the temperature difference control device can be a heating device (e.g., an electric heater or other type of heating device). In other embodiments, the temperature difference control device can be a cooling device (e.g., a chiller, a chilling device, etc.).

[0022] In an eleventh aspect, the plant process in which the heat exchanger apparatus is utilized can be liquefaction via a liquefaction apparatus and the first refrigerant feed conduit can be fluidly connected to a liquefier of the liquefaction apparatus.

[0023] In a twelfth aspect, the heat exchanger apparatus can include a storage tank configured to store a cryogenic liquid. The storage tank can be fluidly connectable to the first heat exchanger so that a boiloff vapor of the cryogenic liquid is feedable to the first heat exchanger as the process stream. In some embodiments, the storage tank can be fluidly connectable to the first heat exchanger via the first refrigerant feed conduit so that the boiloff vapor of the cryogenic liquid is feedable to the first heat exchanger as the process stream, for example.

[0024] In a thirteenth aspect, the heat exchanger apparatus can include a separator fluidly connectable to the first heat exchanger so that a separator boiloff gas from the separator is feedable to the first heat exchanger as the process stream. In some embodiments, the separator can be fluidly connectable to the first heat exchanger via the first refrigerant feed conduit so that the separator boiloff gas from the separator is feedable to the first heat exchanger as the process stream, for instance.

[0025] In a fourteenth aspect, the heat exchanger apparatus can include a column assembly of an air separation unit (ASU) fluidly connectable to the first heat exchanger so a stream output from the column assembly is passable to the first heat exchanger as the process stream. In some embodiments, the column assembly can be fluidly connectable to the first heat exchanger via the first refrigerant feed conduit so that the stream output from the column assembly is passable to the first heat exchanger as the process stream, for example.

[0026] In a fifteenth aspect, the heat exchanger apparatus of the ninth aspect, can include one or more features of the tenth aspect, eleventh aspect, twelfth aspect, thirteenth aspect, and / or fourteenth aspect. Embodiments can also include other features or elements. Examples of other features or elements can be appreciated from the exemplary embodiments of the heat exchanger apparatus discussed herein, for instance.

[0027] In a sixteenth aspect, a plant is provided. The plant can include a liquefaction apparatus including at least one liquefier and a heat exchanger apparatus positioned upstream of the at least one liquefier. The heat exchanger apparatus can be positioned to cool a feed to be fed to the at least one liquefier via at least one refrigerant output from the at least one liquefier during operation of the liquefaction apparatus to liquify the feed. The heat exchanger apparatus can include a recirculation conduit arrangement positioned and configured so that a process stream is feedable to the heat exchanger apparatus to maintain a temperature profile of the heat exchanger apparatus while the liquefaction apparatus is shutdown. The recirculation conduit arrangement can include a temperature difference control device so that the process stream is outputtable from the heat exchanger apparatus, adjusted in temperature via the temperature difference control device, and subsequently recirculated to the heat exchanger apparatus.

[0028] In a seventeenth aspect, the temperature difference control device can be configured so that the process stream is outputtable from the heat exchanger apparatus, adjusted in temperature via the temperature difference control device, and subsequently recirculated to the heat exchanger apparatus to mimic a heat transfer that occurs to cool the feed to be fed to the at least one liquefier via the at least one refrigerant output from the at least one liquefier. In some embodiments, the temperature difference control device can be configured as a heating device or a cooling device.

[0029] In an eighteenth aspect, the plant can be configured to implement an embodiment of the process for operating a heat exchanger apparatus. The plant can also include an embodiment of the heat exchanger apparatus of the ninth aspect, tenth aspect, eleventh aspect, twelfth aspect, thirteenth aspect, fourteenth aspect, or fifteenth aspect.

[0030] It should be appreciated that embodiments of the process, plant, and apparatus can utilize various conduit arrangements and process control elements. The 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), for example. Various different conduit arrangements and process control systems can be utilized to meet a particular set of design criteria.

[0031] Other details, objects, and advantages of our heat exchanger apparatus, process for operating a heat exchanger apparatus, and methods of making and using the same will become apparent as the following description of certain exemplary embodiments thereof proceeds.

[0032] Throughout the specification, ranges expressed as being "between" a first value "and" a second value are to be interpreted as including the first and second values. For example, the expression "a temperature between 0°C and 50°C" is equivalent to "a temperature in a range from 0°C to 50°C". Other ranges are to be interpreted accordingly.

[0033] Exemplary embodiments of our heat exchanger apparatus, process for operating a heat exchanger apparatus, 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. Figure 1 (which can also be referred to as FIG. 1) is a block diagram of an exemplary embodiment of a plant 1 that can utilize an embodiment of the heat exchanger apparatus 10. The first, second, or third exemplary embodiments of the heat exchanger apparatus 10 illustrated in Figures 3-5 can be utilized in this exemplary embodiment of the plant 1. Figure 2 (which can also be referred to as FIG. 2) is a block diagram of an exemplary embodiment of a plant 1 that can utilize an embodiment of the heat exchanger apparatus 10. The first, second, or third exemplary embodiments of the heat exchanger apparatus 10 illustrated in Figures 3-5 can be utilized in this exemplary embodiment of the plant 1. Figure 3 (which can also be referred to as FIG. 3) is a schematic flow chart illustrating a first exemplary embodiment of a process of operating a first exemplary embodiment of a heat exchanger apparatus 10 in which the heat exchanger apparatus 10 can be switched between operating in an operational state OP and a temperature maintenance state TM. Figure 4 (which can also be referred to as FIG. 4) is a schematic flow chart illustrating a second exemplary embodiment of a process of operating a second exemplary embodiment of a heat exchanger apparatus 10 in which the heat exchanger apparatus 10 can be switched between operating in an operational state OP and a temperature maintenance state TM. Figure 5 (which can also be referred to as FIG. 5) is a schematic flow chart illustrating a third exemplary embodiment of a process of operating a third exemplary embodiment of a heat exchanger apparatus 10 in which the heat exchanger apparatus 10 can be switched between operating in an operational state OP and a temperature maintenance state TM. Figure 6 (which can also be referred to as FIG. 6) is a flow chart illustrating an exemplary embodiment of a process of operating a heat exchanger apparatus. Embodiments of the plant 1 and heat exchanger apparatus 10 can be configured to implement this exemplary embodiment of the process of operating the heat exchanger apparatus.

[0034] The reference numerals utilized in the drawings include the following: 1plant 3compression system (COMP. SYS) 5pre-purification unit (PPU) 7ASU heat exchanger apparatus (HX) 9source(s) of process stream(s) 21 10heat exchanger apparatus (HX) 11liquefier 12air separation unit (ASU) 13column assembly 14liquefier feed 15liquefaction apparatus 15awarm components of liquefaction apparatus 15bcold components of liquefaction apparatus 15cfeed processing components of liquefaction apparatus 20recirculation temperature difference control device 21plant process stream 22purified feed 22afirst stream of warm fluid 22bsecond stream of warm fluid 23refrigerant process fluid flow 23afirst stream of refrigerant fluid 23bsecond stream of refrigerant fluid 23cthird stream of refrigerant fluid 25valve 30valve 31recirculation conduit arrangement 40valve 50valve 100first warm fluid feed conduit 110first warm fluid heat exchanger output conduit 150second warm fluid feed conduit 160second warm fluid heat exchanger output conduit 200first refrigerant fluid feed conduit 201first split feed conduit segment 202cooled recirculated stream 203first split output conduit segment 204second split feed conduit segment 205second split output conduit segment 210first refrigerant output conduit 250warmed recirculation fluid flow 260spent recirculation gas stream 300second refrigerant fluid feed conduit 310second refrigerant output conduit 400third refrigerant fluid feed conduit 410third refrigerant output conduit Arargon TMMtemperature maintenance mechanism FGSfeed gas system GNgaseous nitrogen GOgaseous oxygen LNliquid nitrogen LOliquid oxygen LPliquefaction apparatus product stream OPoperational state TDCDtemperature difference control device TMtemperature profile maintenance state S1first step S2second step S3third step

[0035] Valves 25, 30, 40, and 50 can be adjustable between an open position and a closed position. In Figures 4 and 5, a valve is indicated as being in an open position when the valve is shown with a white color fill with black lines. When in a closed position, the valve is shown in solid black color.

[0036] Referring to Figures 1-6, an industrial plant 1 can be configured to receive one or more flows of feed fluid or utilize one or more feed fluids and process that feed fluid(s) to form one or more product fluids. The product fluids may be utilized as a product fluid for storage and / or transport. Alternatively, the product fluids may be utilized for another downstream plant or plant process (e.g., formation of an oxidant stream to feed to a combustion device for combusting a fuel, etc.).

[0037] In some embodiments, a plant 1 can include a liquefier apparatus 15 that can include a feed gas system (FGS). The feed gas system 15c can compress and / or treat a feed gas for feeding to at least one liquefier for liquefaction of a product stream (e.g., product liquid nitrogen stream etc.). The feed gas system 15c can output a compressed gas stream that is sufficiently purified for liquefaction of the feed gas stream to a heat exchanger apparatus 10 for being cooled therein for feeding to downstream liquefaction components 15b that are configured to operate at cold temperatures (e.g., cryogenic or near cryogenic temperatures). The heat exchanger apparatus 10 can be in fluid communication with a temperature difference control device (TDCD) 20 that can be selectively operated depending on the operational state of the heat exchanger apparatus 10. Also, the heat exchanger apparatus 10 can be in fluid communication with cold components of the downstream liquefaction components 15b for passing the feed that has been cooled via the heat exchanger apparatus 10 to the liquefaction components to liquify the gas to form at least one product stream LP, which can be output for storage in a storage device or utilized in another downstream use.

[0038] When the heat exchanger apparatus 10 is not operating to cool a feed to a pre-selected temperature range that may be suitable for the downstream liquefaction components, the heat exchanger apparatus 10 can be adjusted from a first operational state to a second state (e.g., from a normal operational state to a non-operational state). In the second state, the heat exchanger apparatus 10 can receive a flow of refrigerant as a process stream 21 from one or more sources of at least one process stream 9 and no longer receive the feed for pre-cooling the feed. Such a flow of the process stream can be actuated via adjustment of a valve 25 positioned between the source(s) of the process stream(s) 9 and the heat exchanger apparatus 10 for feeding the process stream 21 to the heat exchanger apparatus 10 when it is in a non-operational state and for ceasing the feeding of the process stream to the heat exchanger apparatus 10 when it is in an operational state for effecting heat transfer of a feed stream during operations of a plant 1 (e.g., to pre-cool a feed for liquefaction, etc.).

[0039] The source(s) of at least one process stream 9 can be a heat exchanger 7 of an air separation unit (ASU), a stream of cold fluid that is provided by a column of the ASU 12, a boil-off gas output from a storage tank storing a cryogenic liquid, or other suitable refrigerant. A feed of refrigerant output from the source(s) of at least one process stream 9 can be fed to the heat exchanger apparatus 10 while the heat exchanger apparatus 10 is not receiving flows of fluid for cooling a feed to provide to the downstream liquefaction components 15b to maintain a temperature profile of the heat exchanger apparatus 10 (e.g., maintain a pre-selected temperature difference between the warm and cold ends of the heat exchanger apparatus 10, etc.). The temperature profile that is to be maintained can be selected so that the heat exchanger apparatus 10 is maintained at its operational temperature profile while not in operation. This can reduce thermal stress that may be incurred by the heat exchanger apparatus 10 while it is not operating to cool a feed for feeding to the liquefaction components 15b and can also permit the heat exchanger apparatus 10 to be restarted more quickly when the heat exchanger apparatus 10 is returned to an operational state for cooling a feed output from the FGS 15c.

[0040] The process stream 21 can be fed as a refrigerant to the heat exchanger apparatus 10 at a first colder temperature and output from the heat exchanger apparatus 10 before being vented or recycled back to the source(s) of at least one process stream 9. Alternatively, the output warmed refrigerant utilized to maintain a temperature profile of the heat exchanger apparatus 10 can be output from the heat exchanger apparatus 10 and fed to the temperature difference control device 20, wherein the stream can be heated or cooled to a recycle temperature for being fed back to the heat exchanger apparatus 10 for heat exchange with the stream of colder refrigerant fed into the heat exchanger apparatus 10. The cooled recycled stream of refrigerant can then be output from the heat exchanger apparatus 10 for being vented, being recycled back to the source of the refrigerant 12, or being otherwise utilized in a downstream process or other plant process. The temperature difference control device 20 can be operated to help maintain the temperature difference between refrigerant fed into the heat exchanger apparatus 10 to help maintain the temperature profile of the heat exchanger and avoid overcooling of the heat exchanger apparatus 10 while it is in the second operational state.

[0041] When resumption of liquefaction operations is to continue, the heat exchanger apparatus 10 can be returned to its first operational state such that the refrigerant is no longer fed to the heat exchanger apparatus 10 and the feed from the FGS 15c is fed to the heat exchanger apparatus 10. This adjustment in operation and resumption of liquefaction can occur more quickly because of the maintained temperature profile of the heat exchanger apparatus 10, which can permit the return to liquefaction operations to occur more quickly.

[0042] The adjustment in operation between active liquefaction operations and non-liquefaction operations can occur based on the availability of renewable power and / or other operational criteria. The heat exchanger apparatus 10 and the TDCD 20 can be operated to facilitate the adjustment in operational states so that liquefaction operations can be brought online more quickly for a more effective utilization of renewable power (e.g., renewable power provided by solar power or wind power, etc.) and / or lower cost available power.

[0043] For example, in some embodiments, the plant 1 can include a compression system 3 (COMP. SYS.), which can receive a feed of gas for compressing that feed to a pre-selected feed pressure for feeding downstream of the compression system 3 for use in downstream processing of the plant 1. In some embodiments, there may be one or more booster compressors positioned downstream of the compression system to increase the pressure of one or more portions of the feed fluid output from the compression system 3 as well.

[0044] The compression system 3 can output a pressurized feed to a pre-purification unit (PPU). The PPU 5 can be configured as an adsorption system in some embodiments. For example, the PPU 5 can include a temperature swing adsorption (TSA) system, a pressure swing adsorption (PSA) system, or other type of adsorption system. The PPU 5 can be configured to remove one or more impurities from the pressurized feed fluid output from the compression system 3 for feeding a purified feed to a main heat exchanger apparatus 7 of an ASU 12. For example, the PPU 5 can utilize one or more adsorbers having adsorbent material therein to remove water, carbon dioxide, and / or other constituents of a feed to purify the feed of fluid so the purified feed can be fed to the main heat exchanger apparatus 7.

[0045] The heat exchanger apparatus (HX) 7 of the ASU 12 can include at least one heat exchanger positioned to cool the pressurized and purified feed output from the PPU 5 via heat exchange with one or more refrigerant process fluid flows fed to the heat exchanger apparatus 7 when the plant 1 is operating to produce one or more product fluids. The one or more refrigerant process fluid flows can be warmed via absorption of heat from the purified feed fed to the heat exchanger apparatus 7 for outputting warmed refrigerant process fluid flow(s) for either venting, utilization as a regeneration gas for the PPU, or other use of the warmed fluid output from the heat exchanger apparatus 7.

[0046] In some embodiments, the purified feed fed to the heat exchanger apparatus 7 for being cooled therein can include one or more flows of fluid that are in a temperature range of between 0°C and 50°C. The one or more refrigerant process fluid flows fed to the heat exchanger apparatus 7 for cooling of the purified feed can be in a cryogenic temperature range (e.g., a temperature range of between -150°C and -200°C or between -160°C and -195°C, etc.). The central portion of the heat exchanger apparatus 7 that can be located internal to the housing of the heat exchanger between its inlet and outlet ends that receive the feed and refrigerant flows and output the cooled feed and warmed refrigerant flows can have a temperature profile during operation in which the heat from the warmer purified feed flow(s) is transferred to the cooler refrigerant process fluid flow(s) 23 that may be significantly colder than ambient conditions. The temperature may be lower in the portion adjacent the end of the heat exchanger apparatus 7 at which the cooled purified feed is output from the heat exchanger apparatus 7 and may be warmer in the portion adjacent the end of the heat exchanger apparatus 7 at which the warm purified feed is fed to the heat exchanger apparatus.

[0047] The cooled purified feed of fluid output from the heat exchanger apparatus 7 can be fed to a downstream processing unit of the plant 1. The downstream processing unit can be, for example, a column assembly 13 of an air separation unit (ASU) 12 in some embodiments. In such embodiments, the purified feed can be purified air and the feed may be air. The ASU 12 can include a plurality of columns of a column assembly 13 that include a low pressure column and a high pressure column for receiving the feed of purified air that is cooled via the heat exchanger apparatus 7 for the separation of the air to form one or more product fluids. The one or more product fluids can include, for example, gaseous nitrogen (GN), liquid nitrogen (LN), gaseous oxygen (GO), liquid oxygen (LO). In some embodiments, the column assembly 13 can also include one or more additional columns that can be positioned and configured to receive fluid from the low pressure column and / or high pressure column to also form a product stream of argon (Ar) and / or other product stream(s). The argon product stream that may be formed can be a liquid argon or a gaseous argon for feeding to a storage tank or to a downstream process that may utilize the argon fluid, for example.

[0048] The column assembly 13 can also output one or more streams of nitrogen. At least one of the streams of nitrogen can be sufficiently pure for forming a liquefied product stream. Such stream(s) can be output from the column assembly 13 for being fed to the heat exchanger apparatus 7 to function as a refrigerant therein for cooling of purified feed air to be fed to the column assembly 13. The product stream of nitrogen may then be fed to warm liquefaction components 15a (Liq. Comp. (warm)) as a liquefier feed 14. The warm liquefaction components can include a feed compressor or other elements of a feed gas system 15c of the liquefaction apparatus 15, for example. The feed gas system FGS of the warm liquefaction components 15a can also include purification elements (e.g., an adsorber configured to remove impurities from the stream, etc.).

[0049] The feed gas output from the feed gas system FGC can be fed to a heat exchanger apparatus 10 for undergoing heat transfer therein.

[0050] For example, the heat exchanger apparatus 10 can be a pre-liquefaction feed cooler or a cooler of a liquefaction apparatus 15 for cooling the purified feed stream before it is fed to the colder liquefaction components 15b for liquefaction (Liq. Comp. (cold)) to produce a product stream LP for storage of the liquefied product or other use of the liquified product stream LP. The heat exchanger apparatus 10 can also receive a stream of fluid that can function as a refrigerant for cooling the feed of fluid. The stream(s) of fluid that can function as a refrigerant for cooling of the feed of fluid can be recirculated portions of the feed that may be fed to one or more expanders or other elements to facilitate cooling of the feed for liquefaction. The stream(s) of fluid that can function as a refrigerant for cooling of the feed of fluid during operation of the heat exchanger apparatus 10 of a liquefier 11 for liquefaction operations can also include one or more streams output from the cold liquefaction components prior to the stream(s) being vented or recycled, for example. The cooled feed can be cooled to a pre-selected liquefaction feed temperature for undergoing liquefaction and / or pressure reduction via one or more downstream cold liquefaction components 15b (e.g., one or more liquefiers or liquefier elements).

[0051] In some embodiments, the feed fed to the heat exchanger apparatus 10 for being cooled therein can include one or more flows of fluid that are in a temperature range of between 0°C and 50°C. The one or more refrigerant process fluid flows 23 fed to the heat exchanger apparatus 10 for cooling of the purified feed can be in a cryogenic temperature range (e.g., a temperature range of between -150°C and -200°C or between -160°C and -195°C, etc.). The central portion of the heat exchanger apparatus 10 that can be located internal to the housing of the heat exchanger between its inlet and outlet ends that receive the feed and refrigerant flows and output the cooled feed and warmed refrigerant flows can have a temperature profile during operation in which the heat from the warmer purified feed flow(s) is transferred to the cooler refrigerant process fluid flow(s) 23 that may be significantly colder than ambient conditions. The temperature may be lower in the portion adjacent the end of the heat exchanger apparatus 10 at which the cooled purified feed is output from the heat exchanger apparatus 10 for being fed to one or more downstream liquefiers of the liquefaction apparatus 15 and may be warmer in the portion adjacent the end of the heat exchanger apparatus 10 at which the warm purified feed is fed to the heat exchanger apparatus.

[0052] In some embodiments, the compression system and other elements of the plant 1 (e.g., compression system 3, a feed compressor of the feed gas system 15c of the liquefaction apparatus 15 and / or other components of the liquefaction apparatus 15, etc.) can be run by renewable energy (e.g., electricity powered by solar panels, wind turbines and / or other type of renewable energy source). Other embodiments may rely on conventional electricity production systems (e.g., natural gas or coal powered electricity generation systems, etc.). Embodiments of the plant 1 can be configured so that the liquefier 11 of the plant 1 may be operated when there is sufficient renewable electricity available to power operations or when the pricing of electricity is at or below a pre-selected threshold. When there is insufficient renewable electricity available to power operations or when the pricing of electricity is at or above the pre-selected threshold, operations of the liquefier 11 of the plant 1 can be shut down so the liquefier 11 of the plant 1 does not operate (e.g., the liquefier apparatus 15 does not operate to form one or more product streams and the heat exchanger apparatus 10 is not utilized to cool fluid to support operations of the liquefier apparatus 10 for liquefaction of the fluid etc.).

[0053] Embodiments of the plant 1 can be configured so that the liquefier 11 of the plant 1 and its heat exchanger apparatus 10 can be switched between the operational state and the non-operating state (or shutdown state) one or more times a day or a few times a week (e.g., between 10 and 31 times a month, or between 15 and 25 times a month, etc.). Such an operable configuration, however, can place a significant amount of thermal stress on the heat exchanger apparatus 10 due to the temperature cycling that can occur between when the heat exchanger apparatus 10 is operated to provide heat exchange between warm and cold flows during liquefier 11 operation and when the heat exchanger apparatus 10 is not so utilized during a time when the liquefier 11 of the plant 1 is not operating or is shut down. For instance, the middle of the heat exchanger apparatus 10 may cycle between a temperature of -50°C or -100°C (when the liquefier 11 of the plant 1 is operational) and ambient temperature (when the liquefier 11 of the plant 1 may be in a non-operating state). This type of cyclical thermal change can cause a substantial thermal stress to be incurred by the components of the heat exchanger apparatus 10 if it were to cycle between these temperatures due to differential thermal expansion and contraction that would occur as a result of the temperature gradients. And such stress can be a significant factor in situations where such cycling may regularly occur, which can drastically reduce the lifespan of the heat exchanger apparatus 10 (e.g., leaking and / or failure in the heat exchanger apparatus 10 may occur unexpectedly as a result of such thermal stress events occurring so often).

[0054] To help avoid such problems so that the liquefier 11 of the plant 1 can be more effectively and reliably adjusted between operational and non-operating states to take better advantage of renewable energy availability and / or electricity pricing variances, the heat exchanger apparatus 10 can be configured to utilize a temperature maintenance mechanism (TMM) to help avoid significant thermal cycling from occurring as a result of the liquefier 11 of the plant 1 being switched from its operational state to a non-operating state (or shutdown state). The TMM can be configured to facilitate the use of at least one fluid for being passed through the heat exchanger apparatus 10 while the liquefier 11 of the plant 1 is in a non-operating state to keep the heat exchanger apparatus 10 at the operational temperature profile or within a pre-selected temperature range that is selected to be at or near the operational temperature profile of the heat exchanger apparatus 10 when the liquefier 11 of the plant 1 is operational. For example, embodiments of the TMM can be configured and operated so that the warm end of the heat exchanger apparatus 10 is above -20°C or other suitable temperature and the cold end of the heat exchanger apparatus 10 is below -100°C or other suitable temperature to help minimize or avoid thermal stress being incurred by the heat exchanger apparatus 10 when the liquefier 11 of the plant 1 is not operated (e.g., due to insufficient renewable power being available and / or due to the price of electricity exceeding a pre-selected threshold, etc.). In some embodiments, the TMM can be configured so that the middle of the heat exchanger apparatus (or center portion of the heat exchange apparatus) has a temperature profile that may have a relatively gradual slope in which the temperature may range from between -20°C and -100°C or within another suitable range of temperatures for example.

[0055] As may best be seen from Figures 3-5, the TMM can be configured so that it is not utilized when the heat exchanger apparatus 10 is in an operational state OP when the liquefier 11 of the plant 1 is operating. However, when the liquefier 11 of the plant 1 is adjusted to a non-operating state or a shutdown state, the TMM can be activated and the heat exchanger apparatus 10 can be adjusted to a temperature profile maintenance state TM. When the liquefier 11 of the plant 1 is returned to an operational state OP (e.g., via electricity pricing changing or renewable power availability, etc.), the heat exchanger apparatus 10 can also be adjusted back to its operational state OP and the TMM can be deactivated in conjunction with the switchover from the temperature profile maintenance state TM to the operational state OP. The liquefier 11 of the plant 1 and the heat exchanger apparatus 10 of the liquefier 11 can be adjusted between these different states numerous times a month (e.g., once a day, multiple times a day, a few times a week, multiple times a week, etc.).

[0056] For example, the heat exchanger apparatus 10 can be configured to receive purified feed 22 as a first stream of warm fluid 22a and a second stream of warm fluid 22b. These first and second streams of warm fluid 22a and 22b can be considered a first stream of purified feed and a second stream of purified feed as well. For instance, these streams can be portions of a purified feed of air output from the feed gas system FGS for being pre-cooled before being sent to a downstream liquefier or other downstream liquefaction equipment that can be positioned downstream of the heat exchanger apparatus 10. One such portion of the purified feed may be at a greater pressure than the other such stream in such embodiments.

[0057] The first stream of warm fluid 22a can be fed to the heat exchanger apparatus 10 via a first warm fluid feed conduit 100 connected between the feed gas system FGS and the heat exchanger apparatus 10. The second stream of warm fluid 22b can be fed to the heat exchanger apparatus 10 via a second warm fluid feed conduit 150 connected between the feed gas system FGS and the heat exchanger apparatus 10.

[0058] The heat exchanger apparatus 10 can also be positioned to receive one or more refrigerant flows of fluid 23. For example, the heat exchanger apparatus 10 can be positioned to receive a first stream of refrigerant fluid 23a, a second stream of refrigerant fluid 23b, and a third stream of refrigerant fluid 23c. Each refrigerant fluid may be at a cryogenic temperature. In some embodiments, the refrigerant fluid(s) can include nitrogen and / or oxygen, and may be recycle or waste streams output from at least one downstream liquefier and / or a column of the ASU 12, for example.

[0059] For example, the heat exchanger apparatus 10 can be connected to a first refrigerant fluid feed conduit 200, second refrigerant fluid feed conduit 300 and a third refrigerant fluid feed conduit 400. The first stream of refrigerant fluid 23a can be fed to the heat exchanger apparatus 10 via the first refrigerant feed conduit 200, the second stream of refrigerant fluid 23b can be fed to the heat exchanger apparatus 10 via the second refrigerant feed conduit 300, and the third stream of refrigerant fluid 23c can be fed to the heat exchanger apparatus 10 via the third refrigerant feed conduit 400. The first, second and third refrigerant feed conduits 200, 300, 400 can be connected between the heat exchanger apparatus 10 and the downstream liquefier equipment and / or at least one column of the ASU 12 in some embodiments (e.g., each such conduit can be connected between a low pressure or high pressure column of the ASU column assembly 13 and the heat exchanger apparatus 10 or can be connected between the heat exchanger apparatus 10 and the downstream cold liquefaction equipment).

[0060] The heat exchanger apparatus 10 can include one or more individual heat exchangers and can have different outlet conduits for outputting the cooled purified feed streams and the warmed refrigerant streams fed to the heat exchanger apparatus 10. The one or more heat exchangers of the heat exchanger apparatus 10 can include a first heat exchanger, for example. In some embodiments, the heat exchanger apparatus 10 can also include additional heat exchangers (e.g., a second heat exchanger, a third heat exchanger, etc.).

[0061] The heat exchanger apparatus 10 can include a first warm fluid heat exchanger output conduit 110 through which the cooled warmer fluid of the first stream of warm fluid 22a can be output from the heat exchanger apparatus 10. This conduit can be positioned at an intermediate location along the individual heat exchanger(s) of the heat exchanger apparatus 10 or can be output from a cold end of the heat exchanger apparatus 10.

[0062] The heat exchanger apparatus 10 can also include a second warm fluid heat exchanger output conduit 160 through which the cooled warmer fluid of the second stream of warm fluid 22b can be output from the heat exchanger apparatus 10.

[0063] The heat exchanger apparatus 10 can also include outlet conduits for outputting the warmed refrigerant flows that may be fed to the heat exchanger apparatus. For instance, the heat exchanger apparatus 10 can include a first refrigerant output conduit 210, a second refrigerant output conduit 310, and a third refrigerant output conduit 410. The warmed first stream of refrigerant fluid 23a can be output from the heat exchanger apparatus 10 via the first refrigerant output conduit 210, the warmed second stream of refrigerant fluid 23b can be output from the heat exchanger apparatus 10 via the second refrigerant output conduit 310, and the warmed third stream of refrigerant fluid 23c can be output from the heat exchanger apparatus 10 via the third refrigerant output conduit 410.

[0064] When the heat exchanger apparatus 10 is adjusted to its temperature maintenance state TM, the warm feed streams and the refrigerant feed streams may no longer be fed to the heat exchanger apparatus 10 due to a shutdown of the liquefier 11 of the plant 1. However, at least one of the feed conduits or refrigerant conduits connected to the heat exchanger apparatus 10 can be utilized to receive a refrigerant fluid that may be passed through the heat exchanger to provide cooling therein to help maintain the temperature profile of the heat exchanger apparatus 10 while the liquefier 11 of the plant 1 is in the non-operational state, and the heat exchanger apparatus 10 is in the temperature maintenance state TM. This refrigerant fluid can be provided via a refrigerant process stream 21 that can be operatively connected to the heat exchanger apparatus 10 to route the cooling fluid to the heat exchanger apparatus 10 when the liquefier 11 of the plant 1 is adjusted to a shutdown state, or non-operational state. This refrigerant process stream 21 can be boiloff vapor of cryogenic liquid fluid that can be stored in at least one storage tank (e.g., liquid oxygen, liquid nitrogen, liquid argon, or liquid hydrogen boiloff gas). For instance, such a gas may be cryogenic in temperature and output from a storage tank for venting to reduce the pressure of the storage tank or to maintain the pressure in the storage tank at or below a pre-selected storage pressure. This refrigerant fluid can be fed to the heat exchanger apparatus 10 via the first refrigerant fluid feed conduit 200, second refrigerant fluid feed conduit 300, or third refrigerant fluid feed conduit 400 in some embodiments, where such a feed conduit can be operatively connected to the storage tank via adjustment of one or more valves of a conduit arrangement positioned between the heat exchanger apparatus 10 and the storage tank.

[0065] Alternatively, the refrigerant gas provided to the heat exchanger apparatus 10 while the liquefier 11 of the plant 1 is non-operational and the heat exchanger apparatus 10 is in the temperature maintenance state TM can be provided via another cold process stream (or gas) as the refrigerant process stream 21, which can be provided by another process element of the plant or an adjacent plant or can be separator boiloff gas that may be provided via a separator of the ASU 12 or other plant element or plant unit while the liquefier 11 of the plant is non-operational. The utilized refrigerant process stream 21 can also be provided via a combination of such sources (e.g., a combination of such sources can be the source(s) of at least one process stream 9 in some embodiments, etc.).

[0066] The flow of refrigerant passed through the heat exchanger apparatus 10 while it is in the temperature maintenance state TM can be provided so that the temperature profile of the heat exchanger apparatus 10 is maintained to the same or a pre-selected similar temperature to that which the heat exchanger apparatus 10 has when the liquefier 11 of the plant is operational for making product fluid(s). For example, the flow of the refrigerant process stream 21 can be provided so the warm end of the heat exchanger apparatus 10 is closer to ambient temperature, the cold end of the heat exchanger is at a cryogenic temperature or near cryogenic temperature, and the one or more individual heat exchangers of the heat exchanger apparatus 10 can maintain a temperature profile between the relatively ambient and cryogenic temperatures of the warm and cold ends of the heat exchanger apparatus 10.

[0067] In the exemplary embodiment of Figure 4, the warmed refrigerant gas passed through the heat exchanger apparatus 10 can be vented or sent to another plant element after it is output from the heat exchanger apparatus 10 to help maintain the temperature profile of the heat exchanger apparatus 10. In other embodiments, this refrigerant process stream (or gas) can be recirculated for further use as a working fluid to help maintain the temperature profile of the heat exchanger apparatus 10 while the heat exchanger apparatus 10 operates in the temperature maintenance state TM. Figures 4 and 5 illustrate different recirculation schemes that may be utilized in different embodiments.

[0068] For example, a TMM can include a recirculation conduit arrangement 31 that includes a recirculation conduit connected between a heat exchanger outlet conduit and a heat exchanger feed conduit. The recirculation conduit arrangement 31 can also include a recirculation temperature difference control device 20 positioned to adjust the temperature of the fluid output from the heat exchanger apparatus 10 before it is recirculated back to the heat exchanger apparatus 10 to function as a warming fluid therein as part of the recirculation of the refrigerant process fluid for the maintenance of the temperature profile in the heat exchanger apparatus 10 while it operates in the temperature maintenance state TM. The recirculation conduit arrangement 31 can also include at least one recirculation valve 30, that can be adjusted between a closed position and an open position. In the closed position, no recirculation of fluid may occur. In the open position of the valve(s) 30, fluid can be recirculated via the recirculation conduit arrangement 31 so that recirculated fluid is heated via a recirculation temperature difference control device 20 that is configured as a heating device and subsequently fed back to the heat exchanger apparatus 10.

[0069] For example, in the exemplary embodiment of Figure 4, when the heat exchanger apparatus 10 is adjusted to operate in the temperature maintenance state TM, fluid may only be fed through a single feed and single outlet conduit of the heat exchanger apparatus for the passing of a refrigerant process stream 21 through the heat exchanger apparatus 10 to help maintain the temperature profile of the heat exchanger apparatus 10 as noted above. In the example shown in Figure 4, the first refrigerant fluid feed conduit 200 can receive the refrigerant process stream 21 when the liquefier 11 of the plant 1 is shutdown or not operational and the heat exchanger apparatus 10 is in the temperature maintenance state TM. In some embodiments, this may be the only stream of fluid fed to the heat exchanger apparatus 10 while it operates in the temperature maintenance state TM. As noted above, this refrigerant process stream 21 can be received from at least one storage tank as a boiloff vapor of cryogenic liquid fluid that is stored in the storage tank(s) (e.g., liquid oxygen, liquid nitrogen, liquid argon, or liquid hydrogen boiloff gas). Alternatively, the refrigerant gas provided to the heat exchanger apparatus 10 while the liquefier 11 of the plant 1 is non-operational and the heat exchanger apparatus 10 is in the temperature maintenance state TM can be provided via another cold process gas as the refrigerant process stream 21, which can be provided by another process element of the plant 1 or an adjacent plant or can be separator boiloff gas that may be provided via a separator of the ASU or other plant element or plant unit 1 while the liquefier 11 of the plant 1 is non-operational. The utilized refrigerant process stream 21 can also be provided via a combination of such sources.

[0070] The heat exchanger apparatus 10 can receive that refrigerant process stream 21 via the first refrigerant fluid feed conduit 200 and that fluid can pass through the heat exchanger apparatus 10 to maintain the temperature profile of the heat exchanger apparatus 10 and be output from the heat exchanger apparatus via the first refrigerant fluid output conduit 210. The recirculation valve 30 of the recirculation conduit arrangement can be adjusted from a closed position to an open position so that the refrigerant process stream 21 output from the heat exchanger apparatus can be recirculated back to the heat exchanger apparatus 10 after being output from the heat exchanger apparatus 10 via the first refrigerant fluid output conduit 210. For example, the recirculation valve 30 can be connected to a recirculation conduit that extends between the first refrigerant fluid output conduit 210 and the third refrigerant output conduit 410 or other conduit of the heat exchanger apparatus 10 for passing the refrigerant process stream 21 output from the heat exchanger apparatus 10 back to the heat exchanger apparatus 10. A recirculation temperature difference control device 20 can be positioned in fluid connection with the recirculation conduit arrangement 31 so that the recirculated fluid can be heated to a pre-selected temperature so that there is a warmed recirculation fluid flow 250 that is recirculated back to the heat exchanger apparatus 10 to mimic the relatively ambient warm feed that would be fed to the heat exchanger apparatus 10 when the liquefier 11 of the plant 1 is operational. The warmed recirculated fluid can perform a heat exchange with the colder refrigerant process stream 21 fed into the heat exchanger via the first refrigerant fluid feed conduit 200 when the heat exchanger apparatus operates in the temperature maintenance state TM so that the temperature profile in the heat exchanger apparatus 10 can be maintained to be within a pre-selected temperature range. The warmed recirculated process stream (or gas) may subsequently be output from the heat exchanger apparatus 10 as a spent recirculation gas stream 260, which may be vented or may be recovered for further utilization in another plant process. In such a configuration, the recirculation of the process stream may result in only a single recirculation pass prior to venting or other processing of the spent recirculation gas stream 260.

[0071] When the liquefier 11 of the plant 1 is returned to the operational state, the temperature difference control device 20 can be deactivated and the recirculation valve 30 can be adjusted to a closed position to return the heat exchanger apparatus to its operational state OP.

[0072] The recirculation temperature difference control device 20 can be configured as a heating device (e.g., an electric heater, an ambient air heat exchanger, a heat exchanger that utilizes cooling water or ambient temperature water, or other type of heating device or heater) for heating the recirculated gas of the refrigerant process stream 21 initially output from the heat exchanger apparatus 10 to a pre-selected temperature that can mimic the feed temperature of the purified feed 22 fed to the heat exchanger apparatus 10 when the liquefier 11 of the plant 1 is operational. We have surprisingly found that the added cost and power draw of this recirculation temperature difference control device 20 can be offset by the avoidance or minimization of thermal stress that may be experienced by the heat exchanger apparatus 10 and the improved quickness at which the liquefier 11 of the plant 1 can reach full production rates when the liquefier 11 of the plant 1 is returned to an operational state. For example, the heat exchanger apparatus 10 can be available for effective pre-cooling of feed much more quickly due to it having its temperature profile maintained while the liquefier 11 of the plant is not operational or is shutdown. This can allow the liquefier 11 of the plant 1 to be brought into its operational state much more quickly to take more effective advantage of available renewable power and / or lower electricity pricing, for example.

[0073] Figure 5 illustrates another type of recirculation approach that similarly uses a recirculation conduit arrangement 31. However, the embodiment of Figure 5 utilizes a split stream arrangement in which a feed stream of fluid fed to the heat exchanger apparatus 10 can be split into first and second portions for being fed to the heat exchanger apparatus 10 when the heat exchanger apparatus 10 is in its operational state OP and this split arrangement can also be utilized for the recirculation of the refrigerant process stream 21 when the heat exchanger apparatus 10 is operating in its temperature maintenance state TM. For example, the first refrigerant fluid feed conduit 200 can include a first split feed conduit segment 201 and a second split feed conduit segment 204 for splitting the first refrigerant fluid fed to the heat exchanger apparatus 10 via this conduit into multiple portions for passing through the heat exchanger apparatus 10.

[0074] The first refrigerant fluid output conduit 210 can include a first split output conduit segment 203 through which the first portion of the first refrigerant fluid passed into the heat exchanger apparatus 10 via the first split feed conduit segment 201 is output from the heat exchanger apparatus 10. The first refrigerant fluid output conduit 210 can also include a second split output conduit segment 205 through which the second portion of the first refrigerant fluid passed into the heat exchanger apparatus 10 via the second split feed conduit segment 204 is output from the heat exchanger apparatus 10. These portions can be merged together and passed through the recirculation valve 30 when that valve is in its open position when the heat exchanger apparatus 10 is in its operational state. These split segment portions of the feed and output conduits can also be utilized as the recirculation conduit arrangement 31 via utilization of recirculation valves 30, 40, and 50 that can be in fluid connection with the first refrigerant fluid output conduit 210 and the first refrigerant fluid feed conduit 200.

[0075] For instance, when the heat exchanger apparatus 10 of the embodiment shown in Figure 5 is adjusted to its temperature maintenance state TM, the first recirculation valve 30 can be adjusted to a closed position, a valve 50 of the first split feed conduit segment 201 can also be adjusted from an open position to a closed position, and a valve 40 that is also in fluid communication with the first split feed conduit segment 201 can be adjusted from a closed position to an open position.

[0076] The refrigerant process stream 21 can then be fed to the heat exchanger apparatus 10 via the first refrigerant feed conduit 200 so that this fluid passes through the second split feed conduit 204, through the heat exchanger apparatus 10, and out of the heat exchanger apparatus via the second split output conduit segment 205. The refrigerant fluid can subsequently be heated via a recirculation temperature difference control device 20 that is configured as a heating device that can be in fluid communication with the second split output conduit segment 205 and the first split output conduit segment 203 so that the warmed refrigerant of the refrigerant process stream 21 that is output from the heat exchanger apparatus 10 can be further heated via the recirculation temperature difference control device 20 and subsequently recirculated back to the heat exchanger apparatus 10 via the first split output conduit 203 to mimic feed that may be fed to the heat exchanger apparatus 10 when the liquefier 11 of the plant 1 is in an operational state. This warmed recirculated refrigerant fluid flow 250 can exchange heat with another portion of the refrigerant process stream 21 passed through the heat exchanger apparatus to be subsequently output as a cooled recirculated stream 202 through the first split feed conduit segment 201 that can be directed away from the heat exchanger apparatus 10 via open valve 40 for being vented or for otherwise being utilized (e.g., recovered for being returned to the storage tank from which the fluid may have originated, etc.).

[0077] The heat exchanger apparatus 10 can be returned to its operational state after the liquefier 11 of the plant 1 is returned to an operational state by closing of valve 40 and opening of valves 30 and 50. The temperature difference control device 20 may also be deactivated as it may not be needed when the heat exchanger apparatus 10 is in its operational state. In some embodiments, there may be a bypass conduit arrangement (not shown) so that the fluid output from the second split output conduit 203, when the heat exchanger apparatus 10 is in its operational state OP, can bypass the recirculation temperature difference control device 20 as it is passed toward the first refrigerant output conduit 210. Such a bypass configuration can permit fluid from having to pass through an inoperative temperature difference control device 20 when the heat exchanger apparatus 10 is in its operational state OP.

[0078] Embodiments of the heat exchanger apparatus 10 can also be utilized in yet other embodiments wherein the temperature difference control device 20 can be configured as a cooling device instead of a heating device. In some of these types of embodiments, the refrigerant process stream 21 may be significantly warmed as it is passed through the heat exchanger apparatus 10 and may need to be cooled for being recirculated to provide a desired temperature profile of the heat exchanger apparatus 10 via recirculation of the stream. In such a configuration, the temperature difference control device 20 can be configured as a cooling device by being configured as an expander, a cooler, a Joule-Thomson (JT) valve or other suitable type of cooling device.

[0079] In other embodiments that may utilize the temperature difference control device 20 as a cooling device, the process stream 21 passed into the heat exchanger apparatus 10 can be an ambient temperature fluid and can undergo cooling via the temperature difference control device 20 that is configured as a cooling device so when the process stream 21 is recirculated back to the heat exchanger apparatus 10 it can function as a refrigerant for providing the maintenance of the temperature profile of the heat exchanger apparatus 10. In such a configuration, the initially fed process stream 21 can be fed to a warm end of the heat exchanger (e.g., via a heat exchanger feed conduit through which a purified feed is fed to the heat exchanger apparatus, such as the first warm fluid feed conduit 100) and can be recirculated back to the heat exchanger via a recirculation conduit arrangement that is positioned so that the process stream can be cooled and recirculated back to the heat exchanger apparatus 10 to function as a refrigerant to maintain the temperature profile in the heat exchanger apparatus 10. In such a configuration, the temperature difference control device 20 can be configured as a cooling device by being configured as an expander, a cooler, or a Joule-Thomson (JT) valve.

[0080] Embodiments can be configured so that the temperature difference control device 20 can control the temperature of fluid of the warmed refrigerant to be recycled back to the heat exchanger apparatus 10 to help maintain the temperature profile of the heat exchanger to mimic its temperature profile when in its operational state. The temperature control that is provided can be performed to manage the temperature gradient between the warm and cold ends of the heat exchanger apparatus 10, to mimic the gradient that is present when the heat exchanger apparatus 10 is operational for heat transfer of a feed to provide the feed at a desired pre-selected temperature for liquefaction or other use, so that the thermal stresses that may act on the heat exchanger apparatus 10 as a result of non-operation of the downstream equipment (e.g., liquefiers, etc.) can be avoided or significantly reduced.

[0081] Embodiments of the plant 1, liquefier 11 of the plant 1, and heat exchanger apparatus 10 can be configured to implement a method of operating a heat exchanger apparatus 10. In a first step S1, the heat exchanger apparatus 10 can be operated while the liquefier 11 of the plant 1 is operational. In a second step S2, the liquefier 11 of the plant 1 can be deactivated (e.g., due to unavailability of renewable power, due to electricity pricing being too high, etc.), and the feeding of the warm fluid and refrigerant fluid can be stopped (e.g., the feeding of a purified stream of nitrogen that may be output from a column assembly 13 of an ASU and the feeding of refrigerant fluid(s) via downstream liquefier elements can be stopped). A fluid (e.g., process stream 21) can then be fed to the heat exchanger apparatus 10 for maintenance of a temperature profile of the heat exchanger apparatus 10. Examples of the feeding of such a process stream 21 are discussed above. In some embodiments, the process stream 21 can be recirculated after it is initially output from the heat exchanger apparatus 10, so that the recirculated process stream can be a recirculated process stream (or gas) for undergoing heat exchange with the process stream 21 initially fed into the heat exchanger apparatus 10 to mimic the heat exchange that occurs via the warm fluid and refrigerant fluid fed to the heat exchanger apparatus 10 when the liquefier 11 of the plant 1 is operational.

[0082] As noted above, the recirculated process stream can have its temperature adjusted via use of a temperature difference control device 20 in some embodiments. In some embodiments, the recirculated process stream may be a one-time recirculation pass so that, after being recirculated back through the heat exchanger apparatus 10, the utilized fluid is vented or transported elsewhere for other use in the plant 1.

[0083] In a third step S3, the liquefaction operations can be resumed or restarted (e.g., liquefier 11 operations may be resumed or restarted). In response to the resumption of plant operations, the maintenance of the temperature profile of the heat exchanger apparatus 10 can be stopped and the resumption of the feeding of the warm fluid and the refrigerant fluid can be resumed so that the warm fluid can undergo cooling and the refrigerant fluid can undergo heating via heat exchange with the warm fluid. The process may then return to the first step S1, so that the heat exchanger apparatus 10 is operated while the liquefier 11 of the plant 1 is operational. In such operations, the warm fluid cooled via the heat exchanger apparatus 10 can be cooled to a cryogenic temperature that may be suitable for feeding to a liquefier or other type of equipment that can operate at cryogenic temperatures, for example.

[0084] In other embodiments of the process, the heat exchanger apparatus 10 can be operated while another type of plant process, in which the heat exchanger apparatus 10 is utilized, is operational in a first step S1. In a second step S2, the feeding of fluid to the heat exchanger apparatus 10 to undergo cooling or heating can be stopped in response to the other type of plant process, in which the heat exchanger apparatus 10 is utilized, being stopped (e.g., due to lack of available renewal power, electricity pricing, etc.). A feed of fluid to the heat exchanger apparatus 10 for maintenance of a temperature profile of the heat exchanger apparatus 10 can also be initiated in the second step S2 in response to the change in the operational state of the plant process. In some embodiments (and as discussed above), a temperature difference control device 20 can be utilized to adjust the temperature of the fluid for recirculation of the fluid back to the heat exchanger apparatus 10 as well, to facilitate the maintenance of the temperature profile of the heat exchanger apparatus 10.

[0085] In a third step S3, the maintenance of the temperature profile of the heat exchanger apparatus 10 can be stopped and the resumption of feeding of the fluid to heat exchanger apparatus 10, to undergo cooling and / or heating as an integral part of a process of cooling and / or heating for a downstream process (e.g., air separation, nitrogen liquefaction, etc.) in which the heat exchanger apparatus 10 is utilized, can occur in response to resumption of the other plant process in which the heat exchanger apparatus 10 is utilized (e.g., due to renewable power becoming available or the pricing of electricity changing to a pre-selected suitable level, etc.). The process may then return to the first step S1 so that the heat exchanger apparatus 10 is operated to support the plant process in which the heat exchanger apparatus 10 is utilized.

[0086] Embodiments of the liquefier 11 of the plant 1, the plant 1, and the heat exchanger apparatus 10 can be utilized in embodiments of the process. Such embodiments can implement an embodiment of the process as well.

[0087] The process can also include additional steps or features. For example, the process stream utilized for maintenance of the temperature profile of the heat exchanger can be recirculated via a recirculation conduit arrangement as discussed above. Such recirculation can utilize a temperature difference control device 20 as discussed above.

[0088] In some embodiments, the process stream 21 utilized to maintain the temperature of the heat exchanger apparatus 10 can be boiloff vapor of cryogenic liquid fluid that can be stored in at least one storage tank (e.g., liquid oxygen, liquid nitrogen, liquid argon, or liquid hydrogen boiloff gas). For instance, such a gas may be at cryogenic temperature and output from a storage tank for venting to reduce the pressure of the storage tank or to maintain the temperature in the storage tank at or below a pre-selected storage temperature. In some embodiments, this refrigerant fluid can be fed to the heat exchanger apparatus 10 as the process stream 21 via the first refrigerant fluid feed conduit 200, second refrigerant fluid feed conduit 300 or third refrigerant fluid feed conduit 400 wherein such a conduit can be operatively connected to the storage tank via adjustment of one or more valves of a conduit arrangement positioned between the heat exchanger apparatus 10 and the storage tank. Alternatively, the process stream 21 can be provided to the heat exchanger apparatus 10, while the liquefier 11 of the plant 1 is non-operational and the heat exchanger apparatus 10 is in the temperature maintenance state TM, via another cold process gas as the refrigerant process stream 21, which can be provided by another process element of the plant or an adjacent plant, or can be separator boiloff gas that may be provided via a separator of the ASU or other plant element or plant unit while the plant is non-operational. The utilized refrigerant process stream 21 can also be provided via a combination of such sources.

[0089] In yet other embodiments, the process stream utilized in the second step S2 of the process may be an ambient temperature stream and the temperature difference control device 20 can be configured to cool that stream for recirculation of the fluid as discussed above.

[0090] In some embodiments, the heat exchanger apparatus 10 can be positioned to heat a feed stream instead of cooling the feed stream. The equipment downstream of the heat exchanger apparatus 10 can utilize the heated stream for other processing (e.g., combustion of a fuel, etc.). In such embodiments, the process stream 21 can be from a source of a heating medium instead of a source of a refrigerant.

[0091] It should also be appreciated that other modifications can also be made to meet a particular set of criteria for different embodiments of the plant 1, liquefier 11 of the plant 1, heat exchanger apparatus 10, or process. 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, compressors, fans, valves, conduits, etc.), can be arranged to meet a particular plant layout design that accounts for available area of the apparatus, sized equipment of the apparatus, and other design considerations. As another example, the flow rate, pressure, and temperature of the fluid, passed through one or more heat exchangers as well as passed through other plant elements, can vary to account for different plant design configurations and other design criteria. As yet another example, the number of plant units and how they are arranged can be adjusted to meet a particular set of design criteria. As yet another example, the material composition for the different structural components of the units of the plant and the plant can be any type of suitable material as may be needed to meet a particular set of design criteria.

[0092] As yet another example, embodiments of the liquefier 11, plant 1, heat exchanger apparatus 10, and the process can each be configured to include or utilize 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 or process as well.

[0093] 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.

Claims

1. A process for operating a heat exchanger apparatus (10), the process comprising: feeding at least a first feed fluid to a heat exchanger apparatus (10) and feeding at least a first refrigerant fluid to the heat exchanger apparatus (10) while a plant process is operational to cool the first feed fluid and heat the first refrigerant fluid; in response to deactivation of the plant process, ceasing the feeding of the first feed fluid to the heat exchanger apparatus (10) and the feeding of the first refrigerant fluid to the heat exchanger apparatus (10) and feeding at least one process stream to the heat exchanger apparatus (10) to maintain a temperature profile of the heat exchanger apparatus (10) while the plant process is deactivated.

2. A process according to Claim 1, wherein the at least one process stream includes either a boiloff vapor of cryogenic liquid fluid stored in at least one storage tank or a separator boiloff vapor.

3. A process according to Claim 1 or Claim 2, comprising: outputting the at least one process stream from the heat exchanger apparatus (10) while a liquefier (11) of the plant process is deactivated and recirculating the output at least one process stream back to the heat exchanger apparatus (10).

4. A process according to Claim 1 or Claim 2, comprising: outputting the at least one process stream from the heat exchanger apparatus (10) while a liquefier (11) of the plant process is deactivated, heating the at least one process stream after it is output from the heat exchanger apparatus (10), and recirculating the output at least one process stream back to the heat exchanger apparatus (10) as at least one recirculated process stream.

5. A process according to Claim 4, comprising: outputting the at least one recirculated process stream from the heat exchanger apparatus (10) to vent the recirculated process stream, wherein the at least one recirculated process stream optionally has a temperature in a range from 0°C to 50°C when it is returned to the heat exchanger apparatus (10).

6. A process according to any of the preceding claims, wherein the at least one process stream includes a refrigerant process stream at a temperature in a range from -150°C to -200°C.

7. A process according to any of the preceding claims, wherein the first feed fluid is comprised of nitrogen and / or oxygen, the first feed fluid being at a temperature in a range from 0°C to 50°C and the first refrigerant fluid being at a temperature in a range from -150°C to -200°C.

8. A process according to any of the preceding claims, comprising: adjusting valves to feed the at least one process stream to the heat exchanger apparatus (10) to maintain the temperature profile of the heat exchanger apparatus (10) while a liquefier (11) of the plant process is deactivated; and optionally wherein the at least one process stream is comprised of a boiloff vapor of cryogenic liquid fluid stored in at least one storage tank, a stream output from a column assembly (13) of an air separation unit (ASU) (12), and / or a separator boiloff gas.

9. A heat exchanger apparatus (10) comprising: a first heat exchanger fluidly connectable to at least a first warm fluid feed conduit (100) and a first refrigerant feed conduit (220) such that a refrigerant is feedable to the heat exchanger apparatus (10) via the first refrigerant feed conduit (200) to cool a feed fluid fed to the heat exchanger apparatus (10) via the first warm fluid feed conduit (100) while a plant process to which the heat exchanger apparatus (10) is utilized is operational; and a recirculation conduit arrangement positioned to recirculate a process stream passed into the first heat exchanger via the first refrigerant feed conduit (200) while the plant process is shutdown to maintain a temperature profile of the heat exchanger apparatus (10) while the plant process is shutdown.

10. A heat exchanger apparatus (10) according to Claim 9, wherein the recirculation conduit arrangement comprises a temperature difference control device (20).

11. A heat exchanger apparatus (10) according to Claim 10, wherein the temperature difference control device is a heating device or a cooling device.

12. A heat exchanger apparatus (10) according to any of Claims 9 to 11, wherein the plant process includes liquefaction via a liquefaction apparatus (15) and the first refrigerant feed conduit (200) is fluidly connected to a liquefier (11) of the liquefaction apparatus (15).

13. A heat exchanger apparatus (10) according to any of Claims 9 to 12, comprising: a storage tank configured to store a cryogenic liquid, the storage tank being fluidly connectable to the first heat exchanger so that a boiloff vapor of the cryogenic liquid is feedable to the first heat exchanger as the process stream.

14. A heat exchanger apparatus (10) according to any of Claims 9 to 13, comprising: a separator fluidly connectable to the first heat exchanger so that a separator boiloff gas from the separator is feedable to the first heat exchanger as the process stream; or a column assembly (13) of an air separation unit (ASU) (12) fluidly connectable to the first heat exchanger so a stream output from the column assembly (13) is passable to the first heat exchanger as the process stream.

15. A plant (1) comprising: a liquefaction apparatus (15) including at least one liquefier (11) and a heat exchanger apparatus (10) positioned upstream of the at least one liquefier, the heat exchanger apparatus (10) positioned to cool a feed to be fed to the at least one liquefier (11) via at least one refrigerant output from the at least one liquefier (11) during operation of the liquefaction apparatus (15) to liquify the feed, the heat exchanger apparatus (10) including: a recirculation conduit arrangement positioned and configured so that a process stream is feedable to the heat exchanger apparatus (10) to maintain a temperature profile of the heat exchanger apparatus (10) while the liquefaction apparatus (15) is shutdown, the recirculation conduit arrangement including a temperature difference control device (20) so that the process stream is outputtable from the heat exchanger apparatus (10), adjusted in temperature via the temperature difference control device (20), and subsequently recirculated to the heat exchanger apparatus (10); and optionally wherein the temperature difference control device (20) is configured so that the process stream is outputtable from the heat exchanger apparatus (10), adjusted in temperature via the temperature difference control device (20), and subsequently recirculated to the heat exchanger apparatus (10) to mimic a heat transfer that occurs to cool the feed to be fed to the at least one liquefier (11) via the at least one refrigerant output from the at least one liquefier (11).

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