Gas thermal compression system

Abstract

The present invention relates to a system for the thermal compression of a gas, comprising a source (1), a destination (2) and at least one group of reservoirs (3) each comprising at least two reservoirs (3), characterized in that the system comprises heating means (4) for heating and cooling means (5) for cooling the contents of each reservoir, each group further comprising: - transfer means (6a, 6b) for transferring gas directly from said source to each reservoir and directly from each reservoir to said destination; and - two-way transfer means (7) for each reservoir (3) of said group, allowing to transfer gas directly between said reservoir (3) and at least one other reservoir (3) of said group. Furthermore, the present invention relates to a circulation method for the thermal compression of a gas in a plurality of reservoirs (3) of at least one group of the system according to the invention.

Description

[Technical Field]

[0001] This invention relates to the field of gas compression, specifically to a thermal compression system for gas, and more precisely, to dihydrogen.

[0002] Against the backdrop of robust growth in low-carbon solutions for transportation, as well as for the transport of goods and passengers, dihydrogen appears to be a promising fuel. When used in combination with fuel cells and electric motors in automobiles, it could potentially replace fossil fuels or the batteries commonly used as power sources for electric motors.

[0003] Because dihydrogen has a low density, it needs to be compressed to a pressure of approximately 700 bar before it can be used as fuel. Typically, it is delivered to service stations at a pressure of 200 bar, where it is compressed to 450-1000 bar by a compressor.

[0004] Typically, these compressors are mechanical and have several drawbacks. Moving parts can cause hydrogen leaks. The pistons are not lubricated because lubrication would introduce impurities into the dihydrogen, damaging the fuel cell and causing the pistons to wear out quickly. Furthermore, these compressors consume electricity, resulting in enormous costs and worsening the environmental balance of dihydrogen. Finally, mechanical compressors generate high levels of noise pollution, which is a problem, especially at service stations in urban areas.

[0005] In response to these problems, thermochemical metal hydride compressors have been developed. Metal powder absorbs dihydrogen at low pressure, forming a metal hydride. These hydrides are then heated, releasing the dihydrogen at high pressure. Ideally, these compressors operate between 20 and 500 bar. Outside this operating range, it is difficult to find metal powders that can be compressed at temperature levels that meet industrial standards. In particular, at very high pressure levels, the energy required to further increase the pressure is enormous compared to mechanical compressors, which consume energy roughly equal to the ratio of outlet pressure to inlet pressure. Therefore, combining a thermochemical compressor with a mechanical compressor allows for reaching the final pressure stage.

[0006] Alternatively, a thermal compressor can be used. US Patent No. 20120028140 proposes a compressor that includes multiple reservoirs connected in series, where heating the upstream reservoir increases the pressure between two consecutive reservoirs. This method does not provide high flow rates and consumes too much energy.

[0007] One objective of the present invention is to provide an energy-efficient compressor, particularly one for pressures exceeding 500 bar, that is free from the problems of wear, power consumption, noise, and leakage associated with mechanical compressors.

[0008] An object of the present invention is to at least partially address the aforementioned object by proposing a circulation process for the thermal compression of gas, in which several reservoirs in one group perform a cycle in which a pressure increase is carried out in contact with a reservoir, or a series of high-temperature reservoirs, and then a pressure decrease is carried out to increase the pressure in other low-temperature reservoirs. To this end, the present invention proposes a circulation process for the thermal compression of gas in multiple reservoirs in at least one group of the system, and each cycle is carried out for each reservoir in each group as follows: - The steps include cooling the gas stored in the reservoir and transferring the gas from the supply source to the reservoir, - A step of transferring gas from a donor reservoir to a reservoir, wherein the donor reservoir is the reservoir with the lowest gas pressure among the group of reservoirs whose gas has a higher pressure and temperature than the gas in the reservoir, until the pressures of the reservoir and the donor reservoir are equal, and this step is repeated as long as there are other reservoirs in the group whose gas has a higher pressure and temperature than the gas in the reservoir, if necessary. - The steps include heating the gas stored in the reservoir and transferring the gas from the reservoir to the destination, - A step of transferring gas from the reservoir to a receiving reservoir, the receiving reservoir being the reservoir with the highest gas pressure among the group of reservoirs where the gas has a lower pressure and temperature than the gas in the reservoir, until the pressures of the reservoir and the receiving reservoir are equal, and repeating this step as long as there are other reservoirs in the group where the gas has a lower pressure and temperature than the gas in the reservoir, if necessary. The steps of cooling the gas stored in the reservoir and transferring the gas from the supply source to the reservoir are performed sequentially for each reservoir in the group.

[0009] With these configurations, the gas is compressed to high pressure by thermal compression, avoiding problems related to noise and wear on mechanical parts. The heat used to increase the pressure in one reservoir is then used to compress the contents of other reservoirs as the pressure decreases, allowing for cascading compression, making this process particularly energy-efficient.

[0010] Further characteristics indicate, - The process can be carried out in multiple reservoirs of two groups, so that the steps of cooling the gas stored in one reservoir and transferring the gas from the supply source can be performed sequentially to one of the reservoirs in one group before proceeding to one of the reservoirs in the other group. As a result, the process is optimized, and in particular, it becomes possible to supply the system and continuously generate compressed gas. -During the step of transferring gas from the donor reservoir of the same group with higher gas pressure and temperature to the reservoir in question, the transferred gas can be cooled to reduce the temperature rise of the contents of the reservoir in question, thereby maintaining a temperature difference between the reservoir where the pressure is rising and the reservoir where the pressure is falling, and this difference makes it possible to optimize the compression of the gas in the reservoir in question. -Each group of reservoirs may include at least three, preferably at least four, reservoirs, and each of the two transfer steps may be repeated at least two, preferably at least three times, and by exposing the gas to several pressure stages, it is possible to achieve a higher pressure rise with respect to a given temperature difference. -The process may also include a gas compression step in a metal hydride compressor before transfer from the source to the reservoir, thus combining initial compression, which offers the advantages of a hydride compressor, with thermal compression, which is used when a hydride compressor is unsuitable due to its high-pressure characteristics. -During the step of cooling the gas stored in the first reservoir, heat can be extracted from the first reservoir and used in the step of reheating the gas stored in the second reservoir, thus optimizing the energy consumption of the process. - The step of transferring gas from the supply source to the first reservoir can be performed simultaneously with the step of transferring gas from the second reservoir to the receiving reservoir or destination. Therefore, multiple different steps can be performed simultaneously across multiple different reservoirs in the system, or even within the same group, optimizing the cycle.

[0011] Furthermore, the present invention also relates to a system for thermal compression of gas, the system comprising a source, a destination, and at least one group of reservoirs, each comprising at least two reservoirs, the system comprising means for heating and cooling the contents of each reservoir, the group comprising -Transfer means for directly transferring gas from the supply source to each reservoir, and directly from each reservoir to the destination, -The system further comprises bidirectional transfer means that enable direct gas transfer between each reservoir in the group and at least one other reservoir in the group.

[0012] These configurations allow the gas to be compressed to high pressure through thermal compression, enabling an energy-efficient process while avoiding problems related to noise and wear on mechanical parts.

[0013] Further characteristics indicate, -The gas may be dihydrogen, which is a related embodiment of the present invention, because dihydrogen often needs to be compressed under high pressure to be usable, particularly in transport, and may be, for example, N2, O2, CH4, or helium. - The system may include two groups of reservoirs, thus optimizing its operation and, in particular, enabling the supply to the system and the continuous generation of compressed gas. - The system may include at least three, preferably at least four, reservoirs in each group, and can apply multiple pressure stages to the gas, thereby achieving a greater pressure increase for a given temperature difference. - The heating means can include a waste heat source such as a biomass dihydrogen production plant or electrolytic cell, and the generated heat can be recovered, thus reducing the energy costs consumed by the system. -The cooling means can include a powerful cooling source, such as liquid nitrogen storage or reflux from a chilled water loop, so that available cold air can be recovered and the energy consumed by the system can be reduced. - The supply source includes an evaporated gas outlet from a liquid dihydrogen storage reservoir, enabling the supply of low-temperature dihydrogen to be supplied from the supply source to the reservoir, thereby achieving, in particular, an efficient first compression stage. - The volume of all reservoirs within the same group can be made identical, simplifying the system. [Brief explanation of the drawing]

[0014] The present invention will be better understood by reading the following detailed description while referring to the accompanying drawings. [Figure 1] It is a schematic diagram of a hot gas compression system according to an embodiment of the present invention. [Figure 2] It is a schematic diagram of the steps associated with the hot gas compression process described in FIG. 1. [Figure 3] It is a schematic diagram of the first stage of a hot gas compression process according to a preferred embodiment of the present invention. [Figure 4] It is a schematic diagram of the steps to complete the process starting from FIG. 3.

[0015] The hot gas compression system illustrated in FIG. 1 includes a source 1, a destination 2, and one or more groups of reservoirs 3.

[0016] The system according to the present invention enables the compression of gas from a source 1 where the gas is at pressure P0 to pressure P , target up to.

[0017] The gas related to the present invention is preferably dihydrogen. However, other gases such as oxygen or nitrogen may also be used.

[0018] The reservoir 3 can store the gas of a certain volume in a sealed manner. Within the group, it is preferable that all the reservoirs 3 have the same volume, for example, 50 liters.

[0019] The hot compression system includes heating means 4 and cooling means 5 for heating and cooling the contents of each reservoir 3. The heating means 4 and the cooling means 5 bring the heat transfer fluid into contact with the contents of each reservoir 3. When the heat transfer fluid is at a higher or lower temperature than the contents of the reservoir 3, this heat transfer fluid can be used to heat and cool the contents respectively.

[0020] Furthermore, the heating means 4 may be an electrical resistor immersed in the reservoir.

[0021] Heater 4 can be connected to an electrolytic cell or a biomass dihydrogen production unit. Therefore, if the gas is dihydrogen, the heat generated to produce this dihydrogen can be recovered by the thermal compression system. Depending on the system's location, other locally available waste heat sources can also be connected to the heating system to reduce energy costs. These could be, for example, a waste collection site or another industrial site where heat is generated.

[0022] The thermal compression system further includes a transfer means 6a for directly transferring gas from a source 1 to each reservoir 3 of the group, and a transfer means 6b for directly transferring gas from each reservoir 3 of the group to a destination 2. In this specification, direct transfer means transfer that does not pass through another reservoir 3 of the same group or another group, or through a source 1 or destination 2.

[0023] Finally, the thermal compression system includes bidirectional transfer means (7) that enable the direct transfer of gas from each reservoir in a group to other reservoirs in the same group. In this specification, direct transfer means a transfer that does not pass through another reservoir 3 in the same or another group, or through the source 1 or destination 2. Thus, even considering any pair of reservoirs 3 in the same group, gas can be directly transferred in both directions between these two reservoirs 3.

[0024] The present invention relates to a circulation process for thermally compressing gas in a plurality of reservoirs 3 in at least one group. Each cycle includes the following steps for each reservoir 3a in each group: - The gas stored in reservoir 3a is cooled to a low temperature T1, and the gas is transferred from supply source 1 to reservoir 3a. At the end of this step, reservoir 3a stores gas at pressure P0 and temperature T1. -Transfer gas from another donor reservoir 3 to reservoir 3a. Donor reservoir 3 is the reservoir with the lowest gas pressure among the reservoirs 3 in the same group, where the gas has a higher pressure and temperature than the gas stored in reservoir 3a. When the bidirectional transfer means 7 is opened between reservoir 3a and donor reservoir 3, the transfer is automatically performed until the pressures in reservoir 3a and donor reservoir 3 become equal. During this step, the gas stored in reservoir 3a is compressed. At the end of the first execution of this step, reservoir 3a stores gas at pressure P1 and temperature T1. This step may be repeated several times, as long as there is another reservoir 3 in the same group whose gas has a higher pressure and temperature than the gas stored in reservoir 3a. This step may be repeated, for example, twice if the group contains three reservoirs 3, or three times if the group contains four reservoirs 3. Each time this step is repeated, the pressure in reservoir 3a increases by one step. At the end of this step, reservoir 3a will have pressure P K And store the gas at temperature T1 (K is equal to the number of times the transfer step is repeated). -By heating the gas stored in reservoir 3a to a high temperature T2, the final pressure stage can be established, and the gas is transferred from reservoir 3a to destination 2. At the end of this step, reservoir 3a reaches pressure P K+1 And it stores gas at temperature T2. Pressure P K+1 pressure P target It is close to, or equal to. - The gas is transferred from the reservoir 3a to another receiving reservoir 3. The receiving reservoir 3 is the reservoir with the highest gas pressure among the reservoirs 3 of the same group, where the gas pressure and temperature are lower than the gas in the reservoir 3a. The transfer is performed automatically when the bidirectional transfer means 7 is opened between the reservoir 3a and the receiving reservoir 3, until the pressures in the reservoir 3a and the receiving reservoir 3 become equal. At the end of the first execution of this step, the reservoir 3a is P KStore a gas at a pressure close to or equal to P1 and a temperature T2. This step may be repeated several times as long as there is another reservoir 3 in the group where the gas has a lower pressure and temperature than the gas in reservoir 3a in the reservoir 3. For example, this step may be repeated twice if the group includes three reservoirs 3, or three times if the group includes four reservoirs 3. Each time this step is repeated, reservoir 3a can increase the pressure of another reservoir 3 in the same group by one step. At the end of this step, and during the repetitions until the end, reservoir 3a stores a gas at a pressure close to or equal to P1 and a temperature T2.

[0025] If the volumes of all the reservoirs 3 in the group are the same, the amount of gas in the reservoir 3 can also be determined at each stage as follows. - At the end of the cooling and transfer step of the supply source 1, reservoir 3a stores n0 moles of gas, - At the end of one transfer step from the donor reservoir 3 to this reservoir 3a, this reservoir 3a stores n1 moles of gas, - At the end of all transfer steps from one or more donor reservoirs 3 to this reservoir 3a, this reservoir 3a stores n K moles of gas, - At the end of the heating step and the transfer to transfer destination 2, reservoir 3a stores n K-1 moles of gas, - At the end of one transfer step from this reservoir 3a to the receiving reservoir 3, this reservoir 3a stores n K-2 moles of gas, - At the end of all transfer steps from this reservoir 3a to one or more receiving reservoirs, this reservoir 3a stores n -1 moles of gas.

[0026] The steps of cooling the gas stored in the reservoir and transferring the gas from the supply source to the reservoir 3a are performed simultaneously and sequentially for each reservoir 3 in the group, rather than for several reservoirs 3. In this way, each reservoir 3 in the group goes through this step in turn, and then each follows the same cycle simultaneously, with a time difference relative to the other reservoirs.

[0027] In this process, the gas is thermally compressed by opening the transfer mechanism between the two reservoirs 3, where it is most compressed, allowing the pressure of the gas in the other reservoir to increase. The reservoir receiving the gas is at a low temperature, while the reservoir supplying the gas is at a high temperature. This ensures that, if both reservoirs contain an equal number of moles of gas, the pressure in the high-temperature reservoir will increase, allowing for gas supply and increasing the pressure in the low-temperature reservoir. Thus, each reservoir 3 undergoes a pressure increase at the low temperature followed by a pressure decrease at the high temperature during each cycle. Therefore, reheating and cooling are only required once during the cycle that reservoir 3 goes through.

[0028] It is preferable to cool the transferred gas during the step of transferring gas from another reservoir 3 of the same group, which has higher gas pressure and temperature, to the reservoir in question. This ensures that the temperature of the reservoir 3 receiving the high-temperature gas is kept low and that a temperature difference with the other high-temperature reservoir 3 is maintained. The transferred gas can be cooled before reaching the reservoir 3, for example, in a bidirectional transfer means 7 between the two reservoirs 3. Alternatively, the transferred gas can be cooled after arriving at the reservoir 3, for example, by a cooling means 5, which cools the entire contents of the reservoir 3. In a preferred embodiment of the present invention, the contents of the reservoir 3 cooled to a cold temperature T1 are kept at the cold temperature T1 until the reheating step. Similarly, the contents of the reservoir 3 reheated to a high temperature T2 are preferably kept at the high temperature T2 until the cooling step. This ensures that the temperature difference between T1 and T2 is always available when connecting the high-temperature reservoir 3 to the low-temperature reservoir 3 to increase the pressure of the latter.

[0029] In a preferred embodiment of the present invention, the step of transferring gas from the supply source 1 to the first reservoirs 3a to 3h is performed simultaneously with the step of transferring gas from the second reservoirs 3a to 3h to the receiving reservoir 3 or destination 2. Therefore, while some reservoirs 3 in the system perform a specific step, other reservoirs 3 perform other process steps, saving time.

[0030] To optimize the energy consumption of the process according to the present invention, during the step of cooling the gas stored in the first reservoirs 3a to 3h, the heat extracted from the first reservoirs 3a to 3h can be used in the step of heating the gas stored in the second reservoirs 3a to 3h. For example, a heat transfer fluid can be circulated from the first reservoirs 3a to 3h to the second reservoirs 3a to 3h.

[0031] The reservoir 3 group includes at least two reservoirs 3, for example, three, preferably four reservoirs 3. Along with other system parameters, the pressure P0 at source 1 is transferred to the desired pressure P at destination 2. target The number of reservoirs 3 is selected according to the number of stages required to compress the gas to a certain level. Other parameters to be adjusted include the volume of reservoir 3, as well as the temperatures T1 and T2 at which reservoir 3 is heated and cooled. It is preferable to have an even number of reservoirs 3 in one group. This ensures that in each process step, one of the process steps is performed in each reservoir 3.

[0032] The system may include a single group of reservoirs 3, preferably two groups of reservoirs 3. In fact, the total number of steps in the cycle described above, including the repetition of steps 2 and 4, is equal to twice the number of reservoirs 3 in the group. Therefore, if the system includes a single group, only half of the steps can be performed simultaneously by one of the reservoirs 3. In particular, at each stage of the cycle, the gas transfer step from source 1 to destination 2 is not performed for a single group. Therefore, by operating two groups in parallel, it may be possible to transfer gas from source 1 to one of the system's reservoirs 3 and from one of the system's reservoirs 3 to destination 2 at each stage of the cycle. The number of reservoirs in each group may differ, but in order to obtain the above advantages for two groups, both groups must have either an even or odd number of reservoirs.

[0033] In certain embodiments, an additional reservoir 3 may be provided to enable multi-stage heating and cooling. This is useful when the heating and cooling stages take longer than the transfer stage. Typically, if these stages take twice as long as the transfer stage, performing heating and cooling in two stages can be effective.

[0034] According to another specific design, the equipment can initially operate between a first source pressure P0 and a target pressure P1. Then, in the second stage, a portion of the gas can be extracted at pressure P1 and used as a source at pressure P1. Next, this device increases the pressure to P2. This can be continued for as long as necessary until the final target pressure is reached.

[0035] In a preferred embodiment of the present invention, the source gas pressure P0 is, for example, 400 to 600 bar from a metal hydride compressor, and the target gas pressure P targetThe pressure ranges from 800 bar to 1000 bar. In this configuration, two groups of four reservoirs 3 can be used, and for example, the pressure rise in one reservoir 3a occurs in the following stages: 500 bar at the source, then 560 bar, 635 bar, 725 bar after three stages of transfer from another high-temperature reservoir 3, and finally reaching 810 bar when reservoir 3a is reheated. The gas cooling temperature T1 and reheating temperature T2 are preferably 280K to 310K, for example 293.15K, and 360K to 390K, for example 373.15K, respectively. Needless to say, these temperatures can also be used in combination with other pressure values.

[0036] To optimize energy consumption, the cooling temperature T1 can be set to the lowest possible temperature, i.e., the ambient temperature or the temperature of the coldest cooling source available on-site. For example, liquid nitrogen, recirculation from a chilled water circuit, or other cryogenic fluids may be used if available on-site.

[0037] Alternatively, source 1 can be connected to the evaporator gas outlet of a liquid dihydrogen storage (boil-off gas) at a temperature of 15K to supply the low-temperature dihydrogen to the reservoir from the source.

[0038] The system according to the present invention is particularly advantageous for small-scale facilities where the gas output at destination 2 is 1 kg to 5 kg per hour.

[0039] Regarding pressure / temperature, other applications are also possible. - A supply source connected to the evaporative gas outlet of liquid dihydrogen storage (boil-off gas). - Pressure P0 at supply source 1: 0.5 bar to 2 bar, -Pressure P at destination 2 target : 5 bar to 50 bar, -Cooling temperature T1: 15K~300K, -Heating temperature T2: 300K~400K. - A power source connected to the output of powerful dihydrogen jointly produced in an industrial plant. - Pressure P0 at supply source 1: 0.5 bar to 3 bar, -Pressure P at destination 2 target : 20 bar to 500 bar, -Cooling temperature T1: 253K~353K, -Heating temperature T2: 353K~1000K. - A power source connected to a low-temperature electrolytic cell. - Pressure P0 at supply source 1: 1 bar to 50 bar, -Pressure P at destination 2 target : 2 bar to 200 bar, -Cooling temperature T1: 253K~293K, -Heating temperature T2: 333K~393K. - A power source connected to a high-temperature electrolytic cell. - Pressure P0 at supply source 1: 1 bar to 30 bar, -Pressure P at destination 2 target : 2 bar to 200 bar, -Cooling temperature T1: 253K~293K, -Heating temperature T2: 333K~1073K. - For example, a supply source connected to a thermochemical compressor containing metal hydrides. - Pressure P0 at supply source 1: 200 bar to 500 bar, -Pressure P at destination 2 target : 400 bar to 1000 bar, -Cooling temperature T1: 253K~293K, -Heating temperature T2: 353K~423K. - A supply source connected to the gas cylinder outlet. - Pressure P0 at supply source 1: 50 bar to 500 bar, -Pressure P at destination 2 target : 100 bar to 1000 bar, -Cooling temperature T1: 253K~293K, -Heating temperature T2: 353K~500K. - A supply source connected to a biomass dihydrogen production unit. - Pressure P0 at supply source 1: 1 bar to 5 bar, -Pressure P at destination 2target : 2 bar to 50 bar, -Cooling temperature T1: 253K~293K, -Heating temperature T2: 353K~1073K.

[0040] Figure 2 shows an example of one embodiment, in which the system according to the present invention includes two groups of reservoirs 3a and 3b. The volumes of reservoirs 3a and 3b are equal. In Figure 2, arrows indicate gas flow. After gas transfer is complete, the state of each reservoir is recorded.

[0041] This cycle consists of the following four stages. -Step A: - The gas stored in reservoir 3a is heated to temperature T2, and a portion of this gas is transferred to destination 2. At the end of this step, the pressure of reservoir 3a is P2 = P target It also stores n0 moles of gas at temperature T2. - The gas in reservoir 3b is cooled to a low temperature T1, and the gas is transferred from supply source 1 to reservoir 3b. At the end of this step, reservoir 3b contains n0 moles of gas at pressure P0 and temperature T1. -Step B: - The bidirectional transfer means 7 is opened between reservoir 3a and reservoir 3b, and gas is transferred from reservoir 3a to reservoir 3b. At the end of this step, reservoir 3a has a pressure P1 and a temperature T2 of n -1 Reservoir 3b stores n1 moles of gas at pressure P1 and temperature T1.

[0042] Steps C and D are identical to steps A and B, except that reservoirs 3a and 3b are swapped. At the end of step D, this cycle can be restarted at step A.

[0043] Figures 3 and 4 show an example of one embodiment in which the system according to the present invention includes two groups: four reservoirs 3a to 3d and reservoirs 3e to 3h. The volumes of reservoirs 3a to 3d are equal. The volumes of reservoirs 3e to 3h are equal. In Figures 3 and 4, arrows indicate gas flow. After gas transfer is complete, the state of each reservoir is recorded.

[0044] This cycle consists of eight steps, A through H. The cycle that reservoir 3a follows will be explained below. - Step A: The gas to be stored in reservoir 3a is cooled to a low temperature T1, and the gas is transferred from supply source 1 to reservoir 3a. At the end of this step, reservoir 3a contains n0 moles of gas at pressure P0 and temperature T1. - Step B: The bidirectional transfer means 7 is opened between reservoir 3a and reservoir 3b, allowing gas to be transferred from reservoir 3b to reservoir 3a. At the end of this step, reservoir 3a stores n1 moles of gas at pressure P1 and temperature T1. - Step C: The bidirectional transfer means 7 is opened between reservoir 3a and reservoir 3d, allowing gas to be transferred from reservoir 3d to reservoir 3a. At the end of this step, reservoir 3a stores n2 moles of gas at pressure P2 and temperature T1. - Step D: The bidirectional transfer means 7 is opened between reservoir 3a and reservoir 3c, allowing gas to be transferred from reservoir 3c to reservoir 3a. At the end of this step, reservoir 3a contains n3 moles of gas at pressure P3 and temperature T1. -Step E: The gas stored in reservoir 3a is heated to temperature T2, and a portion of this gas is transferred to destination 2. At the end of this step, the pressure in reservoir 3a is P4 = P target It also stores n2 moles of gas at temperature T2. - Step F: The bidirectional transfer means 7 is opened between reservoir 3a and reservoir 3b, allowing the gas to be transferred from reservoir 3a to reservoir 3b. At the end of this step, reservoir 3a stores n1 moles of gas at pressure P3 and temperature T2. - Step G: The bidirectional transfer means 7 is opened between reservoir 3a and reservoir 3d, allowing gas to be transferred from reservoir 3a to reservoir 3d. At the end of this step, reservoir 3a stores n0 moles of gas at pressure P2 and temperature T2. -Step H: The bidirectional transfer means 7 is opened between reservoir 3a and reservoir 3c, allowing the gas to be transferred from reservoir 3a to reservoir 3c. At the end of this step, reservoir 3a has a pressure P1 and a temperature T2 of n -1 Store the molars of gas. At the end of step H, this cycle can be restarted in step A.

[0045] Naturally, reservoirs 3a to 3h all follow the above cycle and communicate with the relevant reservoir 3 at each transfer stage. - Reservoir 3b starts the above cycle in step C. - Reservoir 3c starts the above cycle in step G. - Reservoir 3d starts the above cycle in step E. - Reservoir 3e starts the above cycle in step B. - Reservoir 3f starts the above cycle in step D. - The 3g reservoir starts the above cycle in step H. - Reservoir 3h starts the above cycle in step F.

[0046] The existence of two groups within the system means that during each stage of the cycle, reservoir 3 receives gas from source 1 and delivers the gas to destination 2. For example, in step A, when reservoir 3d of the first group of reservoir 3 delivers gas to destination 2, then in step B, reservoir 3h of the second group of reservoir 3, and in step C, reservoir 3c of the first group of reservoir 3, and so on. On the other hand, in step A, when reservoir 3a of the first group of reservoir 3 delivers gas to source 1, then in step B, reservoir 3e of the second group of reservoir 3, and in step C, reservoir 3b of the first group of reservoir 3, and so on.

[0047] In this example, by performing the heating and cooling stages over a two-stage transfer period, ten reservoirs 3 are provided instead of eight. These ten reservoirs form a single group, and each reservoir 3 can be connected to three other reservoirs 3 of the ten by bidirectional transfer means. Naturally, each reservoir 3 must be connected to a source and a destination by transfer means.

[0048] While the above description is based on specific embodiments, it is not intended to limit the scope of the present invention, and modifications may be made, in particular, by substitution of technical equivalents or by different combinations of all or some of the features developed above.

Claims

1. A circulation process for thermal compression of gas in a plurality of reservoirs (3) of at least one group of reservoirs (3), wherein each cycle comprises the following steps for each reservoir (3a to 3h) of the plurality of reservoirs (3): - A step of cooling the gas stored in the reservoirs (3a to 3h) and transferring the gas from the supply source (1) to the reservoirs (3a to 3h), - A step of transferring gas from donor reservoir (3) to reservoirs (3a to 3h), wherein the donor reservoir (3) has a higher pressure and temperature than the gas in reservoirs (3a to 3h) and the gas in the same group, and this step is repeated as long as there is another reservoir (3) in the group whose gas has a higher pressure and temperature than the gas in reservoirs (3a to 3h) until the pressures of reservoirs (3a to 3h) and the donor reservoir (3) become equal. - A step of heating the gas stored in the reservoirs (3a to 3h) and transferring the gas from the reservoirs (3a to 3h) to the transfer destination (2), - A step of transferring gas from the reservoirs (3a to 3h) to a receiving reservoir (3), wherein the receiving reservoir (3) has a lower pressure and temperature than the gas from the reservoirs (3a to 3h), and this step is repeated as long as there is another reservoir (3) in the group where the gas has a lower pressure and temperature than the gas from the reservoirs (3a to 3h), until the pressures of the reservoirs (3a to 3h) and the receiving reservoir (3) are equal. A circulating process in which the steps of cooling the gas stored in the reservoirs (3a to 3h) and transferring the gas from the supply source to the reservoirs (3a to 3h) are performed continuously for each reservoir (3) of the group.

2. The process according to claim 1, wherein the donor reservoir (3) is the reservoir with the lowest gas pressure among the group of reservoirs (3) in which the gas has a higher pressure and temperature than the gas in the reservoirs (3a to 3h).

3. The process according to claim 1 or 2, wherein the receiving reservoir (3) is the reservoir with the highest gas pressure among the group of reservoirs (3) in which the gas has lower pressure and temperature than the gas in the reservoirs (3a to 3h).

4. The process according to any one of claims 1 to 3, wherein during the step of transferring gas from the donor reservoir (3) of the same group having higher gas pressure and temperature to the reservoir (3), the transferred gas is cooled to reduce the temperature rise of the contents of the reservoir (3).

5. The process according to any one of claims 1 to 4, further comprising a gas compression step in a metal hydride compressor before transfer from the supply source (1) to the reservoir.

6. The process according to any one of claims 1 to 5, wherein, during the step of cooling the gas stored in the first reservoir (3a to 3h), heat is extracted from the first reservoir (3a to 3h) and used in the step of reheating the gas stored in the second reservoir (3a to 3h).

7. The process according to any one of claims 1 to 6, wherein at least two gas transfer steps are performed simultaneously, the first gas transfer step relating to two entities in the source, the destination, and the reservoir, and the second gas transfer step relating to two entities not relating to the first gas transfer step.

8. The process according to any one of claims 1 to 7, wherein the step of transferring gas from the supply source (1) to the first reservoir (3) is performed simultaneously with the step of transferring gas from the second reservoir (3) to the receiving reservoir (3) or the transfer destination (2).

9. A system configured to implement a process for thermally compressing a gas according to claim 7, comprising a source (1), a destination (2), and at least one group of reservoirs (3), each comprising at least two reservoirs (3), wherein the system also comprises means (4) for heating and means (5) for cooling the contents of each reservoir, and each group is - Transfer means (6a, 6b) for directly transferring gas from the supply source (1) to each reservoir (3), and from each reservoir (3) to the transfer destination (2), - A system further comprising: a bidirectional transfer means (7) for each reservoir (3) of the group, which enables direct transfer of gas between the said reservoir (3) and at least one other reservoir (3) of the group.

10. The system according to claim 9, wherein the gas is dihydrogen.

11. The system according to claim 9 or 10, comprising two groups of reservoirs (3).

12. The system according to any one of claims 9 to 11, wherein each group comprises at least three reservoirs (3).

13. The system according to claim 12, wherein each group comprises at least four reservoirs (3).

14. The system according to any one of claims 9 to 13, wherein the heating means (4) includes a waste heat source.

15. The system according to claim 14, wherein the waste heat source includes a biomass dihydrogen production plant or an electrolytic cell.

16. The system according to any one of claims 9 to 15, wherein the cooling means (5) includes a waste cooling source.

17. The system according to claim 16, wherein the waste cooling source includes a liquid nitrogen storage or recirculation from a chilled water loop.

18. The system according to any one of claims 9 to 17, wherein the supply source (1) includes an evaporative gas outlet from a liquid dihydrogen storage.

19. The system according to any one of claims 9 to 18, wherein the volumes of all reservoirs (3) in the group are the same.

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