Apparatus and method for compressing boil-off gas
By managing the cooling capacity inside the compressor and using counter-flow and diffusion welding heat exchangers for heat exchange, the problems of high energy consumption and expensive materials in the compression of low-temperature evaporative gases in the prior art are solved, and a more efficient and reliable compression process is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BURCKHARDT COMPRESSION AG
- Filing Date
- 2024-12-16
- Publication Date
- 2026-07-17
AI Technical Summary
Existing devices and methods for compressing cryogenic evaporating gases suffer from high energy consumption, low efficiency, and the need to use expensive cryogenic materials.
It adopts a pure compressor internal cooling capacity management method, using counter-flow heat exchangers and diffusion welding heat exchangers to exchange heat between the evaporating gas and the compressor stage, avoiding the preheating system, improving compression efficiency and energy efficiency, and reducing dependence on expensive materials.
It improves compression efficiency and energy efficiency, reduces energy consumption, reduces the need for expensive cryogenic materials, and improves the operational reliability and flexibility of the device.
Smart Images
Figure CN122422698A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to an apparatus and method for compressing evaporated gas for cryogenic storage. Background Technology
[0002] Facilities that process or consume large quantities of gas typically use cryogenic liquefied petroleum gas (LPG) because it is easier to transport and deliver than large quantities of compressed gas. However, when using cryogenic LPG, even when stored in appropriate tanks, the gas will heat up and evaporate due to heat input from the surrounding environment, causing the pressure inside the tank to rise continuously. To prevent the gas pressure inside the tank from exceeding the appropriate pressure specifications, the evaporated gas, also known as boil-off gas (BOG), must be vented from the tank or utilized. Typically, the pressure of the boil-off gas accumulated in the tank is increased in a suitable device before it is delivered to the user. Summary of the Invention
[0003] Because the temperature of the evaporating gas is typically very low, the materials in contact with it must also possess high strength, high ductility, and fatigue resistance at -196°C or lower. This limits the selection of suitable materials and leads to higher material costs. Therefore, existing devices for compressing evaporating gases, such as those used in natural gas and hydrogen compression stations, typically employ ambient temperatures or gas inlet temperatures as low as approximately -40°C or even -160°C, far exceeding -196°C. The compressor's gas inlet temperature is regulated by a preheating system. The energy required to heat the evaporating gas in the preheating system can be obtained, for example, by absorbing heat from the surrounding environment or using an electric preheating device. However, such devices suffer from high energy consumption and waste of the cold energy contained in the evaporating gas.
[0004] Based on the cited prior art, the object of this invention is to mitigate or even eliminate the aforementioned and other disadvantages of the prior art, and to provide an apparatus as mentioned above, characterized by higher compression efficiency and energy efficiency, lower complexity, and thus higher operational reliability, without the need for expensive materials that are particularly stable at low temperatures (especially below approximately -196°C). Another object of this invention is to provide a method for compressing evaporating gases for cryogenic storage, which, compared to methods known in the prior art, has higher compression efficiency and energy efficiency, and eliminates the need for expensive cryogenic materials.
[0005] The objective of this invention is achieved by the apparatus and method described in the independent claims. The dependent claims cover preferred embodiments and further improvements.
[0006] According to the present invention, an apparatus for compressing evaporated gas of a cryogenic storage gas includes a storage tank for the cryogenic storage gas, having an outlet for discharging evaporated gas from which the cryogenic storage gas can be supplied by the storage tank. The apparatus further includes a compressor having at least one compressor stage, preferably at least two compressor stages; and a heat exchanger for heat exchange between the evaporated gas and the evaporated gas compressed in the first compressor stage. The heat exchanger has a first inlet for receiving the evaporated gas; a first outlet for discharging heated evaporated gas to the first compressor stage; a second inlet for receiving the evaporated gas compressed in the first compressor stage; and a second outlet for discharging cooled compressed evaporated gas to a downstream process (particularly a user). For multi-stage compressors, the downstream process may in particular be a second compressor stage of the compressor. The second compressor stage is configured to further compress the evaporated gas compressed by the first compressor stage and cooled in the heat exchanger, thereby providing further compressed evaporated gas.
[0007] Compared to existing devices for compressing evaporating gases, this device is characterized by its purely internal compressor cooling management. In other words, the cooling capacity of the evaporating gas and the heat generated during compression in the first compressor stage are not used for other processes, but are dedicated specifically to cooling the gas within the compressor system. Since the cooling capacity of the evaporating gas is used for the gas pre-compressed in the first compressor stage instead of the preheater, available process cooling capacity is not wasted, thus optimizing the energy efficiency of the compressor system. Furthermore, since there is no need to purchase and operate a preheater with an external heat source, nor to consume separate energy for preheating the evaporating gas (as this energy is provided by the first compressor stage), the efficiency of this device is also improved. Compared to existing devices that preheat the evaporating gas before compression, the above measures can improve energy efficiency by up to 20%. Another advantage of this device is that the compressor, especially the first compressor stage, is not exposed to the low-temperature environment of the evaporating gas. This is particularly important for gases with boiling points lower than nitrogen, as commonly used compressor materials either cannot withstand temperatures below approximately -196°C or are extremely expensive. Therefore, in the manufacturing process of compressors, it is possible to avoid using these expensive materials that can operate normally at extremely low evaporation gas temperatures.
[0008] A storage tank, heat exchanger, and at least two compressor stages for cryogenic gas storage are fluidly connected to each other, allowing the evaporated gas to be transported from the storage tank to the first compressor stage via the heat exchanger. Specifically, the first compressor stage and the heat exchanger are fluidly connected to each other, allowing the evaporated gas compressed in the first compressor stage to be directly supplied to the second inlet of the heat exchanger. Subsequently, the evaporated gas compressed in the first compressor stage can be transported via the heat exchanger to downstream processes, particularly the second compressor stage. The second compressor stage may be followed by one or more subsequent compressor stages of the same compressor or another compressor. Within the scope of this invention, a "subsequent compressor stage" refers to a compressor stage configured to increase the pressure of the gas it supplies.
[0009] In embodiments of this device, the storage tank is suitable for cryogenic storage of gases selected from the group consisting of hydrogen, nitrogen, helium, neon, krypton, argon, liquefied natural gas, oxygen, and mixtures thereof. In a preferred embodiment, the cryogenic storage gas is selected from the group consisting of hydrogen, helium, neon, and mixtures thereof. Because hydrogen (-252°C), helium (-269°C), and neon (-246°C) have extremely low boiling points at atmospheric pressure, the advantages of the device according to the invention are particularly significant when using these gases, as it eliminates the need for typically required cryogenic and expensive materials, especially those used in compressors.
[0010] Particularly preferred is hydrogen, which is used for cryogenic storage.
[0011] In this embodiment of the device, the heat exchanger is a counter-current heat exchanger. Because the fluid flows in opposite directions, a temperature gradient always exists between the material flows (i.e., between the evaporating gas and the evaporating gas compressed in the first compressor stage), so that almost all heat can be transferred from one material flow (i.e., the evaporating gas compressed in the first compressor stage) to the other material flow (i.e., the evaporating gas). Therefore, counter-current heat exchange is more efficient and less expensive than co-current heat exchange, and is also more environmentally friendly due to the associated energy-saving effects.
[0012] Preferably, the heat exchanger is a diffusion-welded counter-flow heat exchanger. Diffusion-welded heat exchangers (Printed Circuit Heat Exchangers; PCHEs) are characterized by a robust heat transfer core, eliminating the need for connectors, seals, or solder joints. This allows for very close proximity of the material flow, resulting in extremely high heat transfer rates and correspondingly high efficiency. Due to these characteristics, diffusion-welded heat exchangers can cool down in a relatively short time, which is particularly advantageous during the start-up phase of the method, as described in detail below. Furthermore, compared to conventional shell-and-tube heat exchangers, diffusion-welded heat exchangers have a very wide performance window and greater resistance to temperature fluctuations and thermal fatigue. The latter helps reduce the total cost associated with repair and maintenance.
[0013] For operational safety reasons, the temperature of the gas exiting the heat exchanger should not be lower than the condensation temperature of nitrogen and / or oxygen. Therefore, it is advantageous for the heat exchanger to have rapid cooling capabilities, as this can shorten the time required to start up the method.
[0014] In an embodiment of this device, a first valve is arranged downstream of the first outlet of the heat exchanger and upstream of the first compressor stage. The first valve is configured to deliver heated evaporating gas to the second compressor stage. The parallel connection of the first and second compressor stages allows, for example, the first compressor stage to be maintained without the need for temporary storage or handling of evaporating gas still accumulating in a storage tank.
[0015] Specifically, the first valve can be located in the pipeline connecting the second outlet of the heat exchanger and the second compressor stage. In this case, the first valve is fluidly connected to the first outlet of the heat exchanger via a first pipeline that branches off from the pipeline connecting the first outlet of the heat exchanger and the first compressor stage.
[0016] In an embodiment of the apparatus, the first outlet of the heat exchanger is fluidly connected to a storage tank via a bypass line located downstream of the first compressor stage and / or the second compressor stage. This bypass line allows compressed evaporating gas to return to the storage tank without requiring the compressed evaporating gas from the first and / or second compressor stages to heat fresh evaporating gas from the storage tank in the heat exchanger. This is particularly advantageous during the start-up phase of the method, which will be described in detail below.
[0017] In an embodiment of the apparatus, the first outlet of the heat exchanger is fluidly connected to or may be fluidly connected to a storage tank via a bypass line arranged downstream of the first compressor stage and / or the second compressor stage, wherein a second valve is arranged downstream of the first compressor stage and upstream of the second inlet of the heat exchanger. The second valve is configured to deliver the compressed evaporating gas from the first compressor stage to the bypass line, rather than to the second inlet of the heat exchanger. Such a bypass line allows the compressed evaporating gas to be returned to the storage tank without using the compressed evaporating gas from the first and / or second compressor stages to heat fresh evaporating gas from the storage tank in the heat exchanger. This is particularly advantageous during the start-up phase of the method, which will be described in detail below. Preferably, the delivery of the compressed evaporating gas from the first compressor stage to the bypass line is done downstream of the second compressor stage via a line located at an opening downstream of the second compressor stage.
[0018] In embodiments of the device, the bypass line may be equipped with a reliquefaction unit for previously compressed evaporating gas. If the user does not extract the evaporating gas after compression, this reliquefaction unit can return the evaporating gas as refrigerant to the storage tank. This reliquefaction unit may, in particular, be a throttle valve.
[0019] In embodiments of this device, the storage tank for cryogenic gas storage can be a mobile cryogenic storage tank, a storage tank of a liquefaction equipment, or a storage tank of a transfer and distribution station.
[0020] In embodiments of this device, the compressor further includes at least one additional compressor stage, which is fluidly connected or potentially fluidly connected to the first and / or second compressor stages. This additional compressor stage is configured to compress the evaporated gas compressed in the first compressor stage and cooled in a heat exchanger. This allows the second compressor stage to be shut down, for example, for maintenance purposes. Additionally or alternatively, the additional compressor stage is also configured to further compress the evaporated gas further compressed in the second compressor stage to provide a further compressed evaporated gas. The presence of the additional compressor stage increases the operational flexibility of the device because it can provide further compressed evaporated gas, for example, according to the pressure requirements of different users.
[0021] This invention achieves its purpose through a method for compressing evaporating gas used in cryogenic storage. The method includes the following steps:
[0022] a) The evaporated gas accumulated in the storage tank with cryogenic storage gas is compressed in the first compressor stage of the compressor, preferably in the first compressor stage of a multi-stage compressor having at least two compressor stages;
[0023] b) The evaporated gas compressed in the first compressor stage is cooled in a heat exchanger; and
[0024] c) The evaporated gas, compressed in the first compressor stage and cooled in step b), is discharged to the downstream process. Specifically, in the downstream process, the evaporated gas, compressed in the first compressor stage and cooled in step b), may be further compressed in the second compressor stage of a multi-stage compressor to obtain a further compressed evaporated gas.
[0025] According to the method of the present invention, before the evaporating gas is compressed in step a), the evaporating gas is heated in a heat exchanger by heat exchange with the evaporating gas compressed in the first compressor stage, thereby obtaining heated evaporating gas. In step b), the cooling of the evaporating gas compressed in the first compressor stage occurs in the heat exchanger by heat exchange with the evaporating gas accumulated in the storage tank and to be compressed in the first compressor stage.
[0026] The advantages of the apparatus disclosed herein can be achieved through this method.
[0027] The method according to the invention can be carried out in particular using the apparatus described herein, thereby also obtaining the advantages of the corresponding apparatus.
[0028] In embodiments of the method, the cryogenic storage gas is selected from the group consisting of hydrogen, nitrogen, helium, neon, krypton, argon, liquefied natural gas, oxygen, and mixtures thereof. Preferably, the cryogenic storage gas is selected from the group consisting of hydrogen, helium, neon, and mixtures thereof. More preferably, the cryogenic storage gas is hydrogen. Here, the advantages of the method according to the invention are particularly significant for low-boiling-point gases, which typically require the use of cryogenically resistant and expensive materials, especially compressor materials.
[0029] In embodiments of the method, heat exchange between the evaporating gas and the evaporating gas compressed in the first compressor stage occurs according to a countercurrent principle. Preferably, the heat exchange between the evaporating gas and the evaporating gas compressed in the first compressor stage is performed using a diffusion-welded heat exchanger. This allows the advantages described in the corresponding embodiments of the apparatus disclosed herein to be achieved.
[0030] For operational safety reasons, the evaporating gas should be heated to a temperature higher than the condensation temperature of nitrogen and / or oxygen. Since heat is generated during gas compression, and higher temperatures can adversely affect compressor efficiency and the materials used in the compressor, the aim should be to compress the gas at the lowest possible temperature.
[0031] In embodiments of the method, the temperature of the evaporated gas accumulated in the storage tank is between -272°C and -160°C. The temperature of the evaporated gas, heated by heat exchange, before compression in step a) (i.e., before compression in the first compressor stage of the multi-stage compressor), is between -196°C and -120°C. Within this temperature range, there is no need to use low-temperature resistant and expensive materials in the compressor. Nevertheless, the lower temperature range is also beneficial for the compression of the evaporated gas because it improves the efficiency of the compression process and helps control the heat generated during compression. This is crucial for achieving higher compression ratios and reducing the thermal stress on compressor components, thereby extending their service life.
[0032] Specifically, this document discloses embodiments of the method in which the evaporated gas, heated by heat exchange, has a temperature between -180°C and -140°C before entering the first compressor stage of a single-stage or multi-stage compressor for compression. This temperature range is particularly preferred, especially when the gas stored at low temperatures is hydrogen, because it avoids the use of expensive materials while maintaining the high efficiency of the first compressor stage.
[0033] In an embodiment of the method, the evaporated gas, compressed in the first compressor stage and cooled in the heat exchanger of step b), is delivered to the second compressor stage at a temperature of -170°C to -60°C. Within this temperature range, the second compressor stage can achieve efficient compression.
[0034] In embodiments of the method, the further compressed evaporating gas, i.e., the evaporating gas obtained from the second compressor stage, is further compressed in at least one subsequent compressor stage. As described above with respect to the corresponding embodiments of the apparatus described herein, this increases the flexibility of the method and allows the evaporating gas to be supplied with the final pressure required by the user.
[0035] Typical users of compressed vaporized gas typically require the following final pressures: 30 to 100 bar when delivered to pipelines, particularly around 60 bar; 350 to 800 bar when loaded in semi-trailers; 16 to 25 bar when used in refineries; 20 to 200 bar when used in ammonia synthesis; and 6 to 65 bar when used for fuel gas supply, particularly for liquid hydrogen generator sets or fuel cell gas turbines.
[0036] In an embodiment of the method, the evaporated gas is first used to cool the heat exchanger for a predetermined period of time, and then used in step b) to cool the evaporated gas compressed in the first compressor stage. In other words, in this embodiment, the evaporated gas flows through the heat exchanger and is then compressed in the first compressor stage, but the evaporated gas compressed in the first compressor stage is not fed into the heat exchanger to exchange heat with the evaporated gas for a predetermined period of time. This allows the heat exchanger to be cooled to the required low temperature particularly quickly.
[0037] The predetermined time can be the time required for the first inlet of the heat exchanger receiving the evaporating gas to reach a predetermined temperature. Alternatively, the predetermined time can be the time required for the heated evaporating gas discharged to the first outlet of the heat exchanger of the first compressor stage to reach a predetermined temperature (particularly a temperature between -196°C and -120°C). This ensures that the temperature of the evaporating gas delivered to the first compressor stage is compatible with the materials used in the first compressor stage.
[0038] In embodiments of the method, the evaporated gas is liquefied in a reliquefaction unit and compressed in at least one of the two compressor stages of the compressor before being returned to the storage tank. The recycling of the evaporated gas is particularly advantageous when there is no user demand for the compressed evaporated gas. Attached Figure Description
[0039] The invention will now be described by way of example with reference to the accompanying drawings. Unless otherwise stated, the same reference numerals always denote components of the same type. Here, they indicate:
[0040] Figure 1a This is a schematic diagram of an apparatus for compressing evaporating gas according to an embodiment of the present invention;
[0041] Figure 1b This is a schematic diagram of an apparatus for compressing evaporating gas according to another embodiment of the present invention;
[0042] Figure 2 This is a schematic diagram of an apparatus for compressing evaporating gas according to another embodiment of the present invention;
[0043] Figure 3a This is a schematic diagram of the material flow during the start-up phase of a method for compressing evaporating gas according to an embodiment of the present invention;
[0044] Figure 3b for Figure 3a A schematic diagram of the material flow after the initiation phase of the method;
[0045] Figure 4a This is a schematic diagram of the material flow during the start-up phase of a method for compressing evaporating gas according to another embodiment of the present invention;
[0046] Figure 4b for Figure 4a A schematic diagram of the material flow after the initiation phase of the method;
[0047] Figure 5 This is a flowchart illustrating possible material flows in a method according to an embodiment of the present invention. Detailed Implementation
[0048] Figure 1a This is a schematic diagram of an embodiment of an apparatus for compressing evaporated gas used in cryogenic storage. Figure 1a As shown, the apparatus 100 includes a storage tank 10 for storing a cryogenic storage gas LG. Within the storage tank 10, cryogenic evaporating gas 1 accumulates and is discharged through an outlet 11 of the storage tank 10. The apparatus 100 also includes a compressor 20 having a compressor stage 21 and a heat exchanger 30, wherein the heat exchanger 30 is configured to exchange heat between the evaporating gas 1 and evaporating gas 3 compressed in the first compressor stage 21. For this purpose, the storage tank 10 is in fluid communication with a first inlet 31 of the heat exchanger through the outlet 11. Therefore, the first inlet 31 of the heat exchanger 30 is configured to receive the evaporating gas 1 and is in fluid communication with a first outlet 32 of the heat exchanger 30. The first outlet 32 of the heat exchanger 30 is in fluid communication with the first compressor stage 21 and is configured to discharge evaporating gas 2 flowing through the heat exchanger 30 to the first compressor stage 21. The first compressor stage 21 is in fluid communication with a second inlet 33 of the heat exchanger 30, the second inlet 33 being configured to receive evaporating gas 3 compressed in the first compressor stage 21. Therefore, the second inlet 33 of the heat exchanger 30 is configured to receive the evaporated gas 3 compressed in the first compressor stage 21 and is in fluid communication with the second outlet 34 of the heat exchanger 30. The second outlet 34 of the heat exchanger 30 is in fluid communication with a user 80 located downstream of the heat exchanger 30, i.e., a downstream process, wherein an additional heat exchanger 60 may be optionally provided between the second outlet 34 of the heat exchanger 30 and the user 80 for further regulation, i.e., cooling or heating of the evaporated gas 4 compressed in the first compressor stage 21 and cooled in the heat exchanger 30, before it is discharged to the user 80. The gas stored cryogenically in the storage tank 10 may in particular be hydrogen. The pressure of the evaporated gas 1 in the top space of the storage tank 10 may be between 1.01 and 20 bar, particularly about 8 bar.
[0049] Figure 1b This is a schematic diagram of a device used to compress evaporated gas for cryogenic storage. (Example) Figure 1bAs shown, the apparatus 100 includes a storage tank 10 for storing a cryogenic storage gas LG. In the storage tank 10, cryogenic evaporating gas 1 accumulates and is discharged through an outlet 11 of the storage tank 10. The apparatus 100 also includes a compressor 20 comprising at least two compressor stages 21 and 22 and a heat exchanger 30. The storage tank 10 is in fluid communication with a first inlet 31 of the heat exchanger through the outlet 11. Therefore, the first inlet 31 of the heat exchanger 30 is configured to receive the evaporating gas 1 and is in fluid communication with a first outlet 32 of the heat exchanger 30. The first outlet 32 of the heat exchanger 30 is in fluid communication with the first compressor stage 21 and is configured to discharge the evaporating gas 2 flowing through the heat exchanger 30 to the first compressor stage 21. The first compressor stage 21 is in fluid communication with a second inlet 33 of the heat exchanger 30, the second inlet 33 being configured to receive the evaporating gas 3 compressed in the first compressor stage 21. The second inlet 33 of the heat exchanger 30 is correspondingly configured to receive the evaporated gas 3 compressed in the first compressor stage 21 and is in fluid communication with the second outlet 34 of the heat exchanger 30. The second outlet 34 of the heat exchanger 30 is in fluid communication with the second compressor stage 22 and is configured to discharge the evaporated gas 4 flowing through the heat exchanger 30 to the second compressor stage 22. The heat exchanger 30 is thus configured to perform heat exchange between the evaporated gas 1 and the evaporated gas 3 compressed in the first compressor stage 21. The second compressor stage 22 is configured to further compress the evaporated gas 4 compressed in the first compressor stage 21 and cooled in the heat exchanger 30 to provide further compressed evaporated gas 5. Downstream of the second compressor stage 22, an additional heat exchanger 60 may be optionally arranged to temperature-regulate the evaporated gas 5 before it is discharged to the user 80. The gas stored cryogenically in the storage tank 10 may in particular be hydrogen. The pressure of the evaporated gas 1 in the top space of the storage tank 10 may be between 1.01 and 20 bar, particularly about 8 bar.
[0050] Figure 2 This is a schematic diagram of an example of a device for compressing evaporated gas used in cryogenic storage. (See diagram for example.) Figure 2 As shown, device 100 includes, in addition to the elements already described in relation to the embodiment shown in FIG1 (the description of which also applies similarly to...), Figure 2 In addition to the illustrated embodiment, an additional compressor stage 23 is included. This additional compressor stage 23 is located after the second compressor stage 22 and is configured to further compress the evaporated gas 5 already compressed in the second compressor stage 22, thereby providing further compressed evaporated gas 6. Figure 2As shown in the group indicated by dashed lines (labeled with reference numeral 20), the additional compressor stage 23 can be part of a compressor that correspondingly includes the first compressor stage 21 and the second compressor stage 22. Alternatively, however, it is also conceivable that the additional compressor stage 23 is part of the additional compressor 20'. Downstream of the additional compressor stage 23, an additional heat exchanger 70 may be optionally provided to cool or heat the further compressed evaporative gas 6 before it is discharged to the user 80. Figure 2 An embodiment of the illustrated apparatus 100 also includes a reliquefaction unit 50 arranged in a bypass line 40 for liquefying previously compressed evaporated gas. The bypass line 40 is fluidly connected to a storage tank 10 to return gaseous or reliquefied evaporated gas 7 in the reliquefaction unit 50 to the storage tank 10. In the illustrated embodiment, the bypass line 40 branches off after a heat exchanger 70 located downstream of the auxiliary compressor stage 23. As will be described in more detail in FIG4, it is also conceivable that the bypass line branches off from the evaporated gas flow at another point in the apparatus 100, particularly after a heat exchanger 60 located downstream of the second compressor stage 22 and optionally upstream of the auxiliary compressor stage 23.
[0051] Figure 3a This is a schematic diagram of the material flow during the start-up phase of a method for compressing evaporating gas according to an embodiment of the present invention. For implementation... Figure 3a The method shown uses device 100, which, in addition to Figure 1b In addition to the elements already described in the illustrated embodiments, the description also applies similarly to the elements already described in the illustrated embodiments. Figure 3a The illustrated embodiment further includes a first valve 41, a second valve 42, a first pipeline 43 branching from upstream of the first compressor stage 21, and a pipeline 44 opening downstream of the second compressor stage 22. The first valve 41 is located downstream of the first outlet 32 of the heat exchanger 30 and upstream of the first compressor stage 21, and is configured to deliver heated evaporated gas from the heat exchanger 30 to the first compressor stage 21 and / or the second compressor stage 22. Figure 3a In the illustrated apparatus, a first valve 41 is arranged in the pipeline fluidly connecting the second outlet 34 of the heat exchanger and the second compressor stage 22, and is fluidly connected to the first outlet via a first pipeline 43, which branches off from the pipeline connecting the first outlet 32 of the heat exchanger 30 to the first compressor stage 21. A second valve 42 is arranged downstream of the first compressor stage 21, more specifically, in the pipeline fluidly connecting the first compressor stage 21 to the second inlet 33 of the heat exchanger. The second valve 42 is also fluidly connected to the apparatus 100 via a second pipeline 44, which opens downstream of the second compressor stage 22. This is for execution. Figure 3aThe apparatus 100 of the method shown also includes an optional bypass line 90, through which a valve 91 can bypass the equally optional heat exchanger 60. If the outlet temperature of the evaporating gas compressed by the first compressor stage 21 and the second compressor stage 22 is lower than the temperature of the cooling medium in the heat exchanger 60, flash gas in the storage tank can be minimized. For greater clarity, Figure 3a The material flow present during method startup, i.e., the path of the evaporated gas 1 through device 100, is indicated in bold. Method startup refers to the state before the actual compression of the evaporated gas begins. During this process, the evaporated gas 1 accumulated in storage tank 10 enters heat exchanger 30 through first inlet 31 and is heated only by the temperature difference between the cold evaporated gas and the higher temperature heat exchanger; that is, it does not exchange heat with the evaporated gas compressed by first compressor stage 21 as it would after normal operation and method startup. In addition to heating the evaporated gas, heat exchanger 30 also cools it. The valve position of first valve 41 allows the evaporated gas to be subsequently compressed in first compressor stage 21 and second compressor stage 22. However, in principle, it is also conceivable that the valve position of first valve 41 allows the evaporated gas to be supplied only to the first compressor stage. Those skilled in the art will understand that, in principle, it is also possible to supply only the evaporated gas to the second compressor stage 22 by appropriately adjusting the position of the first valve in device 100. The valve position of the second valve 42 is such that the evaporated gas compressed in the first compressor stage does not enter the second inlet 33 of the heat exchanger 30, but instead enters through the second pipeline 44 to a location after the second compressor stage 22, where the evaporated gas compressed in the first compressor stage enters the pipeline connecting the second compressor stage 22 and the heat exchanger 60 included in this embodiment. Figure 3a As shown in bold in the material flow diagram, the evaporated gas compressed in the two compressor stages 21, 22 is supplied to the reliquefaction unit 50 via bypass line 90, valve 91, and bypass line 40. Therefore, evaporated gas 1 is recycled from storage tank 10 back to storage tank 10 and / or another storage tank. Figure 3a (Not shown in the text) is used for cryogenic storage of liquefied or gaseous gases.
[0052] Figure 3b yes Figure 3a The diagram illustrates the material flow after the start-up phase of the method, i.e., the process startup situation when the apparatus and method are operating normally. Unless otherwise stated below, Figure 3b The descriptions of the components shown are all based on... Figure 1b and Figure 3a The corresponding description in [the text]. With Figure 3a Compared to the method shown, Figure 3bIn the method shown, the valve position of the first valve 41 is changed, so that the pipeline connecting the first outlet 32 of the heat exchanger 30 and the first compressor stage 21 is no longer in fluid communication with the second compressor stage 22. The valve position of the second valve 42 is also changed, so that the evaporated gas compressed by the first compressor stage 21 is sent into the heat exchanger 30 through its second inlet 33. Therefore, the evaporated gas 1 accumulated in the storage tank 10 is sent into the heat exchanger 30 through its first inlet 31 and exchanges heat with the evaporated gas compressed by the first compressor stage 21 to obtain heated evaporated gas. On the other hand, the evaporated gas compressed by the first compressor stage 21 is cooled in the heat exchanger 30 by exchanging heat with the evaporated gas 1 accumulated in the storage tank 10, which will be compressed in the first compressor stage 21. After being compressed in the first compressor stage 21 and exchanging heat with the evaporated gas 1 from the storage tank 10, the evaporated gas leaves through the second outlet 34 of the heat exchanger and is sent to the second compressor stage 22 to obtain further compressed evaporated gas. Downstream of the second compressor stage 22, the further compressed evaporated gas can be optionally cooled in a heat exchanger 60 before being supplied to the user 80 in the downstream process. Alternatively, the further compressed evaporated gas can be sent to a reliquefaction unit 50 via a bypass line 40, which may be a throttle valve. The coolant recycled in this way is returned to its source storage tank 10. However, additionally or alternatively, it is also conceivable to introduce liquefied evaporated gas into… Figure 3b Another storage tank, not shown, is used for cryogenic gas storage.
[0053] Figure 4a This is a schematic diagram of the material flow during the start-up phase of a method for compressing and evaporating gas according to an embodiment of the present invention. For implementation... Figure 4a The method shown uses device 100, which, in addition to Figure 2 The elements described in the illustrated embodiments (the description of which also applies similarly) Figure 4a In addition to the embodiment shown, it also includes a first valve 41, a second valve 42, a first pipeline 43 branching from upstream of the first compressor stage 21, and a pipeline 44 opening downstream of the second compressor stage 22. The first valve 41 is arranged downstream of the first outlet 32 of the heat exchanger 30 and upstream of the first compressor stage 21, and is configured to deliver heated evaporated gas from the heat exchanger 30 to the first compressor stage 21 and / or the second compressor stage 22. Figure 4aIn the illustrated apparatus, a first valve 41 is arranged in the pipeline connecting the second outlet 34 of the heat exchanger and the second compressor stage 22, and is fluidly connected to the first outlet 32 of the heat exchanger 30 via a first pipeline 43 branching from the pipeline connecting the first outlet 32 of the heat exchanger 30 to the first compressor stage 21. A second valve 42 is arranged downstream of the first compressor stage 21, more precisely, in the pipeline connecting the first compressor stage 21 and the second inlet 33 of the heat exchanger. The second valve 42 is also fluidly connected to a bypass pipeline 40 via a second pipeline 44 leading downstream of the second compressor stage 22 in the apparatus 100. To more clearly illustrate the mass flow present during the method startup process, i.e., the path of the evaporated gas 1 in the apparatus 100, in Figure 4a The text is drawn in bold. Method startup refers to the state before the actual compression of the evaporating gas begins. During this process, the evaporating gas 1 accumulated in the storage tank 10 passes through the first inlet 31 and the heat exchanger 30, and is heated only by the temperature difference between the low-temperature evaporating gas and the higher-temperature heat exchanger; that is, it does not exchange heat with the evaporating gas compressed in the first compressor stage 21, which is the same as the situation after process startup during normal operation of the equipment and method. In addition to heating the evaporating gas, the heat exchanger 30 is also cooled. The valve position of the first valve 41 allows the evaporating gas to be subsequently compressed in the first compressor stage 21 and the second compressor stage 22. However, in principle, it is also conceivable that the valve position of the first valve 41 allows the evaporating gas to be supplied only to the first compressor stage. Those skilled in the art will understand that, in principle, it is also possible to supply only the evaporating gas to the second compressor stage 22 by appropriately adjusting the position of the first valve in the device 100. The valve position of the second valve 42 is such that the evaporated gas compressed in the first compressor stage is not delivered to the second inlet 33 of the heat exchanger 30, but instead reaches a position after the second compressor stage 22 via the second pipeline 44, where the evaporated gas compressed in the first compressor stage enters the pipeline connecting the second compressor stage 22 and the heat exchanger 60. (For implementation) Figure 4aThe apparatus 100 of the illustrated method also includes an optional bypass line 90 with a valve 91 arranged therein for bypassing the equally optional heat exchanger 60 of the apparatus 100. Downstream of the second compressor stage 22 or heat exchanger 60, further compression is optionally performed in another compressor stage 23, followed by cooling in a heat exchanger 70. The apparatus 100 may have an additional bypass line 92 with a valve 93 arranged therein for bypassing the optional heat exchanger 70. By bypassing heat exchangers 60 and 70 respectively, flash gas in the storage tank can be minimized if the outlet temperature of the evaporated gas compressed by the first and second compressor stages 21, 22 or the outlet temperature of the evaporated gas compressed by the third compressor stage 23 is lower than the temperature of the cooling medium in heat exchangers 60 or 70. The evaporated gas is then sent to the reliquefaction unit 50 via bypass line 40. Thus, the evaporated gas 1 from the storage tank 10 is recycled back to the storage tank 10 and / or Figure 4a Additional storage tanks, not shown, are used for cryogenic storage of liquefied or gaseous gases.
[0054] Figure 4b yes Figure 4a A schematic diagram of the material flow in the Chinese method after the start-up phase (i.e., after the process starts during normal operation of the unit and method). Unless otherwise stated below, Figure 4b The descriptions of the components shown are all based on... Figure 2 and Figure 4a Similar descriptions to those in [the text]. With Figure 4a Compared to the method shown, Figure 3bIn the method shown, the valve position of the first valve 41 is changed, so that the pipeline connecting the first outlet 32 of the heat exchanger 30 and the first compressor stage 21 is no longer in fluid communication with the second compressor stage 22. The valve position of the second valve 42 is also changed, so that the evaporated gas compressed by the first compressor stage 21 is sent into the heat exchanger 30 through its second inlet 33. Therefore, the evaporated gas 1 accumulated in the storage tank 10 is sent into the heat exchanger 30 through its first inlet 31 and heated by heat exchange with the evaporated gas compressed by the first compressor stage 21, thereby obtaining heated evaporated gas. On the other hand, the cooling of the evaporated gas compressed in the first compressor stage 21 occurs in the heat exchanger 30 by heat exchange with the evaporated gas 1 accumulated in the storage tank 10 and compressed in the first compressor stage 21. The evaporated gas, after being compressed in the first compressor stage 21 and cooled by the evaporated gas 1 from the storage tank 10, leaves the heat exchanger through the second outlet 34 and is sent to the second compressor stage 22 to obtain further compressed evaporated gas. Downstream of the second compressor stage 22, the further compressed evaporating gas can be optionally cooled in heat exchanger 60 and optionally further compressed in auxiliary compressor 23 to obtain a further compressed evaporating gas. The further compressed evaporating gas can be optionally cooled in heat exchanger 70 located downstream of auxiliary compressor stage 23 before being delivered to user 80. Alternatively, the further compressed evaporating gas can be sent to reliquefaction unit 50 via bypass line 40, which can in particular be a throttle valve. The coolant recovered in this way is returned to its source storage tank 10. However, additionally or alternatively, it is also conceivable that the liquefied evaporating gas could be fed into… Figure 4b An additional storage tank, not shown, is used for cryogenic storage of the gas.
[0055] Figure 5 This is a flowchart illustrating possible material flows conceivable in a method according to an embodiment of the present invention. Specifically, Figure 5To clarify again the terminology used for the evaporating gas in and / or after the process steps in the apparatus: the evaporating gas generated by the evaporation of the cryogenic storage gas LG due to the input of ambient heat in the storage tank 10, before reaching the first outlet of the heat exchanger 30, is referred to as "evaporating gas 1". The evaporating gas leaving the first outlet of the heat exchanger 30 is referred to herein as "heated evaporating gas 2" until the evaporating gas is first compressed in the first compressor stage 21, or, if the heated evaporating gas 2 is sent to the second compressor stage 22 instead of the first compressor stage 21 (as described in some embodiments herein), compressed in the second compressor stage 22. The evaporating gas obtained by compressing the heated evaporating gas 2 in the first compressor stage 21 is referred to as "compressed evaporating gas 3". If the heated evaporating gas 2 is sent to the second compressor stage 22 instead of the first compressor stage 21, the evaporating gas compressed in the second compressor stage 22 is referred to as "compressed evaporating gas 3'" to distinguish it from the evaporating gas 3 compressed in the first compressor stage. It is conceivable that the compressed evaporating gas 3' obtained therefrom will be further compressed in an additional compressor stage 23, different from the second compressor stage 22, to obtain "further compressed evaporating gas 5'", or cooled in the reliquefaction unit 50 to obtain "liquefied evaporating gas 7". The evaporating gas compressed in the first compressor stage 21 exits via the second outlet of the heat exchanger 30, and is referred to herein as "cooled compressed evaporating gas 4". The cooled compressed evaporating gas 4 is sent to the second compressor stage 22, and after being compressed by the second compressor stage 22, it is referred to as "further compressed evaporating gas 5". It is also conceivable, for example, during maintenance work on the second compressor stage 22, that the cooled compressed evaporating gas 4 is sent to the additional compressor stage 23 instead of the second compressor stage. If the cooled compressed evaporating gas 4 is sent to the additional compressor stage 23 instead of the second compressor stage 22, the evaporating gas compressed in the additional compressor stage is referred to as "further compressed evaporating gas 5'" to distinguish it from the evaporating gas 5 further compressed in the second compressor stage 22. The further compressed evaporated gases 5 and 5' can be supplied to user 80, or cooled in reliquefaction unit 50 to obtain "liquefied evaporated gas 7" for return to storage tank 10. Optionally, the further compressed evaporated gases 5 and 5' can be pre-sent to additional compressor stage 23. In this case, after compression by additional compressor stage 23, it is referred to as "further compressed evaporated gas 6". Furthermore, the evaporated gas can be returned to storage tank 10 in a gaseous physical state from the outlets of the respective compressor stages 21, 22, 23. For clarity, each compressor stage... Figure 5 It is not shown separately in the text.
Claims
1. An apparatus (100) for compressing an evaporated gas (1) of a cryogenic storage gas (LG), the apparatus (100) comprising: - A container (10) for cryogenic storage gas (LG), the container (10) including an outlet (11) for discharging the evaporated gas (1) of the cryogenic storage gas (LG) supplied in the container (10); - A compressor (20) having at least one compressor stage (21), preferably having at least two compressor stages (21, 22); - Heat exchanger (30) for heat exchange between evaporating gas (1) and evaporating gas (3) compressed in the first compressor stage (21); -The heat exchanger (30) has a first inlet (31) for receiving evaporating gas (1), a first outlet (32) for discharging heated evaporating gas (2) to a first compressor stage (21), a second inlet (33) for receiving evaporating gas (3) compressed in the first compressor stage (21), and a second outlet (34) for discharging cooled and compressed evaporating gas (4) to a downstream process, particularly to a second compressor stage (22) of the compressor (20), the second compressor stage (22) being configured to further compress the evaporating gas (4) compressed in the first compressor stage (21) and cooled in the heat exchanger (30) to provide further compressed evaporating gas (5).
2. The apparatus according to claim 1, wherein, The cryogenic storage gas (LG) is selected from the group consisting of hydrogen, nitrogen, helium, neon, krypton, argon, liquefied natural gas, oxygen, and mixtures thereof, wherein the cryogenic storage gas (LG) is preferably selected from the group consisting of hydrogen, helium, neon, and mixtures thereof, and hydrogen is particularly preferred.
3. The apparatus according to claim 1 or 2, wherein, The heat exchanger is a counter-flow heat exchanger, preferably a diffusion-welded counter-flow heat exchanger.
4. The apparatus according to any one of the preceding claims, wherein, A first valve (41) is arranged downstream of the first outlet (32) of the heat exchanger (30) and upstream of the first compressor stage (21), through which heated evaporated gas (2) can be supplied to the second compressor stage (22). In particular, the first valve (41) can be arranged in the line fluidly connecting the second outlet (34) of the heat exchanger (30) and the second compressor stage (22) and fluidly connected to the first outlet (32) of the heat exchanger (30) via a first line (43) branching off from the line connecting the first outlet (32) of the heat exchanger (30) to the first compressor stage (21).
5. The apparatus according to any one of the preceding claims, wherein, The first outlet (32) of the heat exchanger (30) is connected to or can be fluidly connected to the container (10) via a bypass line (40) arranged downstream of the first compressor stage (21) and / or the second compressor stage (22).
6. The apparatus according to claim 5, wherein, The second valve (42) is located downstream of the first compressor stage (21) and upstream of the second inlet (33) of the heat exchanger (30), through which the evaporated gas (3) compressed in the first compressor stage (21) is supplied, in particular, via a second line (44) opening downstream of the second compressor stage (22) to the bypass line (40), rather than to the second inlet (33) of the heat exchanger (30).
7. The apparatus according to claim 5 or 6, wherein the bypass line (40) has a reliquefaction device (50) for the previously compressed evaporated gas (3, 5, 6), particularly a throttle valve.
8. The apparatus according to any one of the preceding claims, wherein, The container (10) for cryogenic storage gas (LG) is a mobile cryogenic tank, a tank for liquefaction equipment, or a tank for a transfer terminal.
9. A method for compressing the evaporated gas (1) of a cryogenic storage gas (LG), particularly employing the apparatus according to any one of claims 1 to 8, the method comprising the following steps: a. The evaporating gas (1) generated in a container (10) having cryogenic storage gas (LG) is compressed in the first compressor stage (21) of the compressor (20), preferably, the compressor (20) includes at least two compressor stages (21, 22); b. Cooling the evaporated gas (3) compressed in the first compressor stage (21) in a heat exchanger (30); and c. The evaporated gas (4) compressed in the first compressor stage (21) and cooled in step b) is discharged to the downstream process, in particular to the second compressor stage (22) of the compressor (20) to obtain the evaporated gas (5) which is further compressed; In step a), the evaporating gas (1) is heated in the heat exchanger (30) by exchanging heat with the evaporating gas (3) that has been compressed in the first compressor stage (21) before being compressed in step a), thereby obtaining heated evaporating gas (2); and in step b), the evaporating gas (3) that has been compressed in the first compressor stage (21) is cooled in the heat exchanger (30) by exchanging heat with the evaporating gas (1) that is generated in the container (10) and will be compressed in the first compressor stage (21).
10. The method according to claim 9, wherein, The cryogenic storage gas (LG) is selected from the group consisting of hydrogen, nitrogen, helium, neon, krypton, argon, liquefied natural gas, oxygen, and mixtures thereof, wherein the cryogenic storage gas (LG) is preferably selected from the group consisting of hydrogen, helium, neon, and mixtures thereof, and hydrogen is particularly preferred.
11. The method according to claim 9 or 10, wherein, The heat exchange between the evaporating gas (1) and the evaporating gas (3) compressed in the first compressor stage (21) is carried out in a countercurrent manner, preferably using a diffusion-welded heat exchanger.
12. The method according to any one of claims 9 to 11, wherein, The temperature of the vapor gas (1) generated in the container (10) is between -272°C and -160°C, and the temperature of the vapor gas (1) heated by heat exchange before compression in step a) is between -196°C and -120°C, especially between -180°C and -140°C.
13. The method according to any one of claims 9 to 12, wherein, The evaporated gas (4) compressed in the first compressor stage (21) and cooled in step b) is supplied to the second compressor stage (22) at a temperature of -170°C to -60°C.
14. The method according to any one of claims 9 to 13, wherein, The evaporating gas (1) is used for a predetermined period of time, specifically until a predetermined temperature is reached at the first inlet (31) of the heat exchanger (30) for receiving the evaporating gas (1) and / or at the first outlet (32) of the heat exchanger (30) for discharging the heated evaporating gas (2) to the first compressor stage (21), in order to cool the heat exchanger (30) before cooling the evaporating gas (3) compressed by the first compressor stage (21) in step b).
15. The method according to any one of claims 9 to 14, wherein, The vaporized gas (3,5) compressed in at least one of the two compressor stages (21,22) is reliquefied and returned to the container (10).