System for transforming a product

Abstract

The present invention relates to a system for transforming a product, the product being in the gas state when it is at a pressure of 1 bar and a temperature of 283 K, the system comprising: - at least one liquid product tank (8); - a main circuit (10) for extracting a main product in the liquid state from the liquid product tank; and - a recovery circuit (12) comprising at least one thermal compressor (13) configured to at least partially compress a gas by raising the temperature of the gas or of an intermediate agent such as a metal hydride by means of a cold source and a heat source, and transfer means for transferring a recovery product resulting from evaporation inside the liquid product tank (8) to one of the at least one thermal compressor (13), the cold source of at least one of the thermal compressors (13) being configured to receive cold energy from the main circuit (10). The present invention also relates to a method for transforming a product.

Description

Product transformation system

[0001] The present invention relates to the field of transforming a liquid product into a gaseous product. It relates to a system and a method for transforming a liquid product, and in particular liquid hydrogen.

[0002] In a context of strong development of low-carbon dioxide emission solutions for mobility and the transport of goods and passengers, dihydrogen appears to be a promising fuel. Its use, combined with a fuel cell and an electric motor in a vehicle, can represent an alternative to fossil fuels or the use of electric accumulators commonly used to power electric motors.

[0003] Due to its low density in the gaseous state, dihydrogen is sometimes stored in liquid form to save space. In some cases, it must then be evaporated and compressed to a pressure of around 350 or 700 bars to be used as fuel.

[0004] In order to remain in a liquid state under atmospheric pressure, hydrogen must be kept at a temperature below 20K. Since this temperature is much lower than ambient temperature, some of the liquid hydrogen inevitably evaporates, a phenomenon called "boil-off".

[0005] Hydrogen resulting from boil-off is difficult to recover economically because it is produced in small quantities at low pressures. In most cases, this hydrogen is therefore released into the atmosphere, where it is lost. These losses can represent up to 1% of the quantity of liquid hydrogen stored per day. There is therefore a particular interest in finding solutions to recover this hydrogen.

[0006] Documents WO2005068847 and WO2015036708 propose devices for recovering boil-off gas. The energy consumed is optimized thanks to heat exchangers located in the boil-off gas circuit. However, these devices consume too much energy.

[0007] An object of the present invention is to propose a system for transforming a product, said product being in the gaseous state when it is at a pressure of 1 bar and a temperature of 283 K in which the gaseous product resulting from the "boil off" is recovered while optimizing the consumption of energy and / or material.

[0008] The object of the present invention is to respond at least in part to the aforementioned objects by proposing a transformation system making it possible to compress the gaseous product resulting from the "boil-off" by using the cold energy contained in the product which is liquefied at low temperature.To this end, it proposes a system for transforming a product, said product being in the gaseous state when it is at a pressure of 1 bar and a temperature of 283K, said system comprising: at least one liquid product reservoir, a main circuit configured to extract a main product in the liquid state from the liquid product reservoir, and a recovery circuit comprising at least one thermal compressor configured to compress a gas at least in part by raising the temperature of said gas or of an intermediate agent such as a metal hydride, using a cold source and a hot source, and transfer means making it possible to transfer a recovery product resulting from evaporation inside the liquid product reservoir to one of said at least one thermal compressor, the cold source of at least one of said thermal compressors being configured to receive cold energy from said main circuit.

[0009] Thanks to these provisions, the recovered product resulting from the “boil-off” phenomenon can be compressed to a pressure level making it recoverable, while consuming little energy.

[0010] According to other characteristics: the main circuit may comprise at least one evaporator and transfer means for transferring a main product in the liquid state from the liquid product reservoir to one of said at least one evaporator, which makes it possible to use the cold energy emitted by the main product during its evaporation, said cold source of at least one of said at least one thermal compressor may comprise a cold circuit configured to be traversed by a heat transfer fluid thermally connected to said evaporator, which is a simple and effective embodiment of the invention, said cold source of at least one of said at least one thermal compressor may comprise a cold circuit configured to be traversed by said main product, which makes it possible to optimize the use of the cold energy contained in the liquefied main product,the hot source of at least one of said at least one thermal compressor can be thermally connected to the ambient air, which is a low energy consuming hot source,the recovery circuit can comprise:at least one first thermal compressor, the cold source of which is configured to receive cold energy from said main circuit and the hot source is thermally connected to the ambient air, anddownstream of said at least one first thermal compressor with respect to the movement of said second gaseous product, at least one second thermal compressor, the cold source of which is configured to receive cold energy from said main circuit or from the ambient air and the hot source is thermally connected to a fatal heat source or to an electric heater,

[0011] which makes it possible to obtain a high level of compression of the recovery product while optimizing energy consumption, at least one thermal compressor may be a multi-stage thermal compressor comprising an upstream source, a target, and at least one group of reservoirs each comprising at least two reservoirs, said multi-stage thermal compressor comprising a means for heating and a means for cooling the contents of each reservoir, linked respectively to a hot source and a cold source, each group further comprising: transfer means for transferring gas directly from said upstream source to each reservoir and directly from each reservoir to said target, and for each reservoir of said group, bidirectional transfer means for transferring gas directly between this reservoir and at least one other reservoir of said group,

[0012] thus the gas, which in the context of the present invention is the recovered product, can be compressed to a high pressure by thermal compression, which makes it possible to avoid problems of noise and wear of mechanical parts, while allowing an energy-efficient process.said multi-stage thermal compressor can comprise two groups of reservoirs, which makes it possible to optimize its operation, and in particular to allow a continuous supply of the multi-stage thermal compressor and production of compressed gas,said multi-stage thermal compressor can comprise at least three, preferably at least four reservoirs in each group, which makes it possible to raise several pressure stages of the gas, and therefore to obtain a greater pressure rise for a given temperature difference,the hot source can be a fatal heat source such as for example a biomass dihydrogen production plant or an electrolyzer,which allows the heat produced to be recovered, and thus reduces the costs of the energy consumed by the thermal compressor, whether it is a multi-stage thermal compressor or another type of thermal compressor, all the tanks in the same group can have the same volume, which simplifies the multi-stage thermal compressor.,

[0013] The present invention also relates to a method for transforming a product located in a liquid product tank, said product being a product which is in the gaseous state when it is at a pressure of 1 bar and a temperature of 283K, said method comprising the following steps:in a main circuit: extraction of a main product in the liquid state from said liquid product tank,in a recovery circuit: evaporation of liquid product in said liquid product tank to obtain a recovery product in the gaseous state,transfer of said recovery product to at least one thermal compressor,in said at least one thermal compressor, compression of said recovery product at least in part by raising the temperature of said recovery product or of an intermediate agent such as a metal hydride, using a cold source and a hot source,said cold source receiving cold energy from said main circuit.,

[0014] Thanks to these provisions, the recovered product resulting from the “boil-off” phenomenon can be compressed to a pressure level making it recoverable, while consuming little energy.

[0015] According to other characteristics: said method may further comprise, in the main circuit, after the extraction step, a step of evaporation of said main product, which makes it possible to use the cold energy emitted by the main product during its evaporation, the temperature of the liquid product in the liquid product tank may be less than 123 K, which allows the use of air gases in the method according to the invention, the pressure of the gaseous product downstream of said at least one thermal compressor may be greater than or equal to 300 bar, which allows use for example in the field of mobility, said compression of the recovery product may be carried out at least in part by a cyclic process of thermal compression of a gas, which in the context of the present invention is the recovery product,in which several reservoirs of a group carry out a cycle during which they carry out a pressure increase in contact with a reservoir or a succession of hotter reservoirs, then a pressure decrease in order to increase the pressure of other colder reservoirs. The multi-stage thermal compressor can be used according to a cyclic method of thermal compression of a gas in a plurality of reservoirs of at least one group of said thermal compressor, each cycle comprising for each reservoir of each group the following steps: cooling of the gas contained in the reservoir and transfer of gas from the source to said reservoir, transfer of gas from a donor reservoir to said reservoir, said donor reservoir being the one whose gas is at the lowest pressure among the reservoirs of said group whose gas is at a pressure and temperature higher than the gas of said reservoir,until the pressures in said reservoir and said donor reservoir are equalized, if applicable, repeating this step as long as there is another reservoir in said group whose gas is at a pressure and temperature higher than the gas in said reservoir, heating the gas contained in the reservoir and transferring gas from said reservoir to the target, transferring gas from said reservoir to a receiving reservoir, said receiving reservoir being the one whose gas is at the highest pressure among the reservoirs in said group whose gas is at a pressure and temperature lower than the gas in said reservoir, until the pressures in said reservoir and said recipient reservoir are equalized, if applicable, repeating this step as long as there is another reservoir in said group whose gas is at a pressure and temperature lower than the gas in said reservoir,

[0016] the step of cooling the gas contained in the tank and transferring gas from the upstream source to said tank being carried out successively for each tank of said group,

[0017] which allows the gas to be compressed to a high pressure by thermal compression, which avoids problems of noise and wear of mechanical parts. This process is particularly energy efficient, the heat used to increase the pressure in a tank being used during its pressure reduction to compress the contents of other tanks, the compression being able to be carried out in cascade. said thermal compression process in a multi-stage thermal compressor can take place in a plurality of tanks of two groups, the steps of cooling the gas contained in a tank and transferring the gas from the upstream source being able to take place in turn to one of the tanks of one group, then to one of the tanks of the other group, which makes it possible to optimize the process, and in particular to allow a continuous supply of the multi-stage thermal compressor and a continuous production of compressed gas,during the step of transferring gas from a donor tank of the same group whose gas is at a higher pressure and temperature to said tank, the transferred gas can be cooled to reduce the rise in temperature of the contents of said tank, which makes it possible to maintain the temperature difference between a tank increasing in pressure and a tank decreasing in pressure, this difference making it possible to optimize the compression of the gas of said tank, each group of tanks can comprise at least three, preferably at least four tanks, and the two transfer steps can each be repeated respectively at least two, preferably at least three times, which makes it possible to raise several pressure stages of the gas, and therefore to obtain a greater pressure rise for a given temperature difference, said thermal compression method, whether it uses a multi-stage thermal compressor or not,may further comprise a step of compressing the gas, after a first thermal compression, in a metal hydride compressor, which makes it possible to combine a first compression offering the advantages of the thermal compressor, then a thermochemical compression when the quantity of cold energy supplied by the main circuit is not sufficient to achieve the desired compression level, during the step of cooling the gas contained in a first tank, heat can be extracted from said first tank and be used in the step of heating the gas contained in a second tank, which makes it possible to optimize the energy consumption of the process, at least two steps can be carried out simultaneously, a first step including a transfer of gas between a first and a second entity, these two entities being the upstream source and a tank, two tanks, or a tank and the target,and a second step including a gas transfer between a third and a fourth entity, these two entities being the upstream source and a reservoir, two reservoirs, or a reservoir and the target, the first, second, third and fourth entities being four distinct entities, which makes it possible to optimize the cycle, several different steps taking place at the same time in several different reservoirs of the multi-stage thermal compressor, or even of the same group. the step of transferring gas from the upstream source to a first reservoir can take place simultaneously with the step of transferring gas from a second reservoir to a receiving reservoir or to the target, which makes it possible to optimize the cycle, several different steps taking place at the same time in several different reservoirs of the multi-stage thermal compressor, or even of the same group.,

[0018] The present invention will be better understood upon reading the detailed description which follows, with reference to the appended figures in which:

[0019] This is a schematic view of a transformation system according to the invention comprising a thermal compressor whose cold source comprises a cold circuit traversed by a heat transfer liquid whose cold energy comes from the main circuit, and the hot source is thermally connected to the ambient air.

[0020] This is a schematic view of a transformation system according to the invention comprising a thermal compressor whose cold source comprises a cold circuit traversed by the main product in the gaseous state and the hot source is thermally connected to the ambient air.

[0021] This is a schematic view of a transformation system according to the invention comprising a thermal compressor whose cold source comprises a cold circuit traversed by the main product circulating in the evaporator and the hot source is thermally connected to the ambient air.

[0022] This is a schematic view of a transformation system according to the invention comprising a thermal compressor whose cold source comprises a cold circuit traversed by a heat transfer liquid and the hot source is hotter than the ambient air.

[0023] This is a schematic view of a transformation system according to the invention comprising a first thermal compressor whose cold source comprises a cold circuit traversed by a heat transfer liquid whose cold energy comes from the main circuit and the hot source is thermally connected to the ambient air, and a second thermal compressor whose cold source is thermally connected to the ambient air and the hot source is hotter than the ambient air.

[0024] This is a schematic view of a transformation system according to the invention comprising a first thermal compressor whose cold source comprises a cold circuit traversed by a heat transfer liquid whose cold energy comes from the main circuit and the hot source is thermally connected to the ambient air, and a second thermal compressor whose cold source comprises a cold circuit traversed by a heat transfer liquid and the hot source is hotter than the ambient air.

[0025] This is a schematic view of a multi-stage thermal compressor according to one embodiment of the invention,

[0026] This is a schematic view of the steps of a method of thermal compression of a gas according to the embodiment of the,

[0027] This is a schematic view of the first steps of a method of thermal compression of a gas in a multi-stage thermal compressor according to a preferred embodiment of the invention,

[0028] This is a schematic view of the steps completing the process started in.

[0029] The transformation system according to the invention, several embodiments of which are illustrated in 6, makes it possible to transform a liquid product into a compressed gaseous product. The product concerned by the invention is in the gaseous state when it is at a pressure of 1 bar and at a temperature of 283K.

[0030] The product concerned by the invention is preferably dihydrogen. However, it may be another product, such as oxygen, nitrogen, methane, helium or natural gas for example.

[0031] The system according to the invention comprises at least one liquid product reservoir 8, and in certain embodiments may comprise at least one compressed gaseous product reservoir 9.

[0032] In the liquid product reservoir 8, the temperature is preferably less than 123K, for example between 15 and 100K, and the pressure is preferably between 1 and 10 bar, for example 1 bar.

[0033] Where appropriate, in the gaseous product tank, the temperature is preferably between 260K and 310K and the pressure is greater than or equal to 2 bars, preferably greater than 300 bars.

[0034] The system according to the invention also comprises a main circuit 10 configured to be traversed by a first part of the product, called the main product, initially stored in the liquid product tank 8.

[0035] The main circuit 10 may comprise at least one evaporator 11.

[0036] In the present invention, the term "evaporator" designates any physical entity in which the main product can evaporate, that is to say pass from the liquid state to the gaseous state. The evaporator 11 can thus be a device dedicated to evaporation, or simply a conduit or any place in which the conditions are such that the main product, initially in the liquid state, passes into the gaseous state.

[0037] When the system according to the invention comprises an evaporator 11, a single evaporator 11 can be used, or a plurality of evaporators 11 can be arranged in parallel.

[0038] The main circuit 10 comprises transfer means for extracting the main product in the liquid state from the liquid product reservoir 8, in certain embodiments to an evaporator 11. In this case the transfer may be direct, or other devices may be passed through by the main product between the liquid product reservoir 8 and an evaporator 11, for example a cryogenic pump. The main circuit 10 is therefore configured to extract the main product in the liquid state from the liquid product reservoir 8. The main circuit 10 may also comprise transfer means for transferring the main product to a gaseous product reservoir 9, for example from the main product in the gaseous state coming from an evaporator 11 to a gaseous product reservoir 9.In this case, this transfer can be direct, or other devices can be crossed by the main product between an evaporator 11 and the gaseous product tank 9.

[0039] The system according to the invention finally comprises a recovery circuit 12 configured to be traversed by a second part of the product, called recovery product, initially stored in the liquid product tank 8. The recovery product is the result of the “boil-off” phenomenon: it is the product which evaporates naturally due to the heating taking place in the liquid product tank 8. All or only part of the product resulting from the “boil-off” evaporation can be sent to the recovery circuit 12 and constitute the recovery product.

[0040] The recovery circuit 12 comprises at least one thermal compressor 13.

[0041] In the context of the present invention, the term "thermal compressor" designates any device capable of compressing a gas at least in part by raising the temperature of this gas, or by raising the temperature of an intermediate agent such as a metal hydride. To generate this temperature rise, the thermal compressor 13 uses a cold source and a hot source.

[0042] According to a preferred embodiment of the invention, at least one thermal compressor 13 is of the multi-stage type as described below. In embodiments comprising several thermal compressors 13, only some or all of the thermal compressors 13 may be of the multi-stage type.

[0043] A single thermal compressor 13 may be used, or a plurality of thermal compressors 13 may be arranged in series, in order to operate several compression stages, and / or in parallel.

[0044] The recovery circuit 12 comprises transfer means for transferring the recovery product in the gaseous state from the liquid product reservoir 8 to a thermal compressor 13. This transfer may be direct, or other devices may be used for the recovery product to pass through between the liquid product reservoir 8 and a thermal compressor 13. The recovery circuit 12 is therefore configured to extract the recovery product in the gaseous state from the liquid product reservoir 8. The recovery circuit 12 may also comprise transfer means for transferring the compressed recovery product from a thermal compressor 13 to a gaseous product reservoir 9. This transfer may be direct, or other devices may be used for the recovery product to pass through between a thermal compressor 13 and the gaseous product reservoir 9.

[0045] In the case where the system according to the invention comprises a single gaseous product tank 9, the main 10 and recovery 12 circuits can transfer the main and recovery products into this single gaseous product tank 9. On the other hand, in the case where the system according to the invention comprises a plurality of gaseous product tanks 9, the main 10 and recovery 12 circuits can either transfer the main and recovery products into the same gaseous product tank 9, or into separate gaseous product tanks 9.

[0046] In other embodiments, the system according to the invention comprises only a single gaseous product reservoir 9 downstream of only one of the main or recovery circuits, or the system according to the invention may not comprise any gaseous product reservoir 9. Indeed, once compressed in the at least one thermal compressor 13, the recovery product can undergo other steps or be used without prior storage. The main product, after having lost part of its cold energy outside the liquid product reservoir 8, can also undergo other steps or be used without prior storage.

[0047] In the present invention, the cold source of at least one of the thermal compressors 13 is configured to receive cold energy from the main circuit 10. Indeed, the main circuit 10 is initially traversed by the main product in the liquid state, at a cold temperature, for example less than 123K. The cold energy contained in the liquid main product is then advantageously reused.

[0048] In a first embodiment of the invention illustrated in 4 to 6, the cold energy is extracted from the main circuit 10 at an evaporator 11, taking advantage of the fact that during its evaporation, cold energy leaves the main product. The cold source of at least one thermal compressor 13 may then comprise a cold circuit 14, configured to be traversed by a heat transfer fluid distinct from the main product. The cold circuit 14 is then thermally connected to at least one evaporator 11, in order to transfer the cold energy from this evaporator 11 to the heat transfer fluid. The heat transfer fluid is then sent to a thermal compressor 13 in order to constitute the cold source.

[0049] The heat transfer fluid can be of the glycol type. It is preferably a silicone-based fluid, which has the advantage of being in the liquid state up to temperatures of around 163K.

[0050] In a second embodiment, the cold source of at least one thermal compressor 13 comprises a cold circuit 14 configured to be traversed by the main product. As illustrated in, the cold energy can then be extracted from the main circuit 10 at an evaporator 11, the evaporator 11 being placed as close as possible to the thermal compressor so that the cold energy is transferred directly from the main product to the thermal compressor 13. In this case, the evaporator 11 has the function of the cold circuit 14 and the cold energy released by the evaporation of the main product directly constitutes the cold source of at least one thermal compressor 13, without using a heat transfer fluid separate from the main product. This may have the disadvantage that the main product is then two-phase at the cold source, making the heat exchanges with the thermal compressor 13 more complex to manage.According to another embodiment illustrated in, the cold energy is extracted from the main circuit 10 downstream of an evaporator 11, when the main product is in the gaseous state. In another embodiment, the cold energy is extracted from the main circuit 10 upstream or in the absence of an evaporator 11, when the main product is in the liquid state.

[0051] The main product is a product such that it is preferably in the liquid state at temperatures below 163K. However, the heat transfer fluids usually used by those skilled in the art cannot fall below this temperature in the liquid state. The use of the main product to constitute the cold source of the thermal compressor 13, without an intermediate heat transfer fluid, therefore makes it possible to operate at lower temperatures, which improves the efficiency of the thermal compressor 13.

[0052] According to a particular embodiment, the pressure in the liquid product tank 8 can be increased up to a value of 10 bar for example. The need to guarantee a high quality of insulation, to minimize the quantity of gas forming in the liquid product tank 8 by the “boil off” phenomenon is not compatible with a very high pressure tank. Nevertheless, it is possible to achieve a value of 10 bar. Thus, the recovered product can be recovered in the recovery circuit 12 at a higher pressure, and therefore enters the first thermal compressor 13 at a higher pressure. This makes it possible to obtain a higher outlet pressure from the thermal compressor 13.

[0053] The hot source of at least one thermal compressor 13 may be thermally connected to the ambient air, for example with a convector to promote heat exchange. This hot source allows for low energy consumption, and may have a sufficient temperature differential with the cold source from the main circuit 10 to operate the desired compression in the thermal compressor 13.

[0054] With a heat transfer fluid at 163K, and two multi-stage thermal compressors 13 as described below arranged one downstream of the other, each thermal compressor 13 using the main circuit 10 as a cold source and a hot source thermally connected to the ambient air, a compression ratio of the order of 20 can then be achieved. For example, with a pressure of the recovery product at 10 bar at the inlet of the first thermal compressor 13, an outlet pressure of the second thermal compressor 13 of around 200 bar can thus be obtained. Depending on the applications, and in particular the flow rate of recovery product and the desired pressure level at the outlet of the at least one thermal compressor 13, a single thermal compressor 13 may be sufficient, or more than two thermal compressors 13 may be arranged in series.

[0055] Alternatively, if a hotter hot source is desired to obtain a greater temperature differential with the cold source, and therefore a greater pressure ratio between the inlet and the outlet of the thermal compressor 13, the hot source of at least one thermal compressor 13 can be connected to a fatal heat source, which makes it possible to optimize the energy consumption of the system, to an electric heater, or to any other hot source known to those skilled in the art and suitable for a thermal compressor, as illustrated in 6.

[0056] Finally, the hot source of at least one thermal compressor can be linked to a catalytic combustion device for a portion of the “boil-off” product evaporating inside the liquid product tank 8. In this case, only a portion of the “boil-off” product is sent to the recovery circuit 12, and another portion of the “boil-off” product is sent to the catalytic combustion device.

[0057] These embodiments can allow higher pressures to be obtained, such as those required in a gas station, 350 or 700 bar depending on the applications. However, to obtain pressures of this order, while using a multi-stage thermal compressor 13, it is necessary to increase the number of tanks used in the compressor and therefore the number of stages and the complexity of the associated process.

[0058] According to a particular embodiment of the invention illustrated in, the system according to the invention comprises at least two thermal compressors 13 in series, the cold source of a first thermal compressor being configured to receive cold energy from the main circuit 10, and the hot source of a second thermal compressor 13 being configured to be hotter than the ambient air. The cold source of the second thermal compressor 13 can then be thermally connected to the ambient air. This cold source allows low energy consumption, and can have a sufficient temperature differential with the hot source to operate the desired compression in the second thermal compressor 13.

[0059] Taking the example above, with an inlet pressure of the first thermal compressor 13 of 10 bar and an outlet pressure of 200 bar, the second thermal compressor 13 can be configured with a pressure ratio of 1.75, or 3.5, to obtain an outlet pressure of 350 bar, respectively 700 bar, while maintaining an attractive energy efficiency.

[0060] Such numerical values ​​are given as an example and in no way limit the scope of the invention; those skilled in the art will know how to configure the system to best meet the needs of each application.

[0061] In another particular embodiment of the invention, illustrated in, the system according to the invention comprises at least two thermal compressors 13 in series, each making it possible to pass a compression stage to the recovered product: a first thermal compressor 13 has its cold source configured to receive cold energy from the main circuit 10, and its hot source thermally connected to the ambient air, and a second thermal compressor 13, located downstream of the first thermal compressor, has its cold source configured to receive cold energy from the main circuit 10, and its hot source thermally connected to a fatal heat source, to an electric heater, or to a catalytic combustion device for a portion of the "boil-off" product evaporating inside the liquid product tank 8.

[0062] This arrangement (and 6) of two thermal compressors 13 in series is particularly advantageous when the quantity of cold energy from the main circuit 10, and the differential with the ambient air temperature, is not sufficient to compress the recovered product to the required pressure level. There is thus a first compression stage carried out in the first thermal compressor 13, insufficient but consuming little energy. The second thermal compressor 13, which is a greater consumer of energy due to its hot source, can bring the recovered product to the required pressure level, the pre-compression step carried out by the first thermal compressor allowing it to start from a higher inlet pressure.

[0063] In the case where the two thermal compressors 13 above are such that their cold source is configured to receive cold energy from the main circuit 10 (), the system may comprise a first cold circuit 14 at the first thermal compressor 13 in which a heat transfer fluid circulates at a temperature between 163K and 180K, and a second cold circuit 14 at the second thermal compressor 13 in which a heat transfer fluid circulates at a temperature between 163K and 233K. Indeed, the main product being at the outlet of the liquid product tank 8 at a temperature between 0K and 163K, the heat transfer fluid cannot fall below 163K and is only capable of capturing a portion of the cold energy contained in the main product. The use of a second cold circuit makes it possible to use a greater portion of this cold energy.The presence of two cold circuits 14 therefore makes it possible to optimize the use of the cold energy released by the main product in the main circuit 10. Depending on the applications, the system according to the invention may comprise three or more thermal compressors 13 in series, each connected to a cold circuit 14, to take full advantage of this benefit.

[0064] The transformation system according to the invention can be used in a method for transforming a product located in a liquid product tank 8. This method comprises the following steps: in a main circuit 10: extraction of a main product in the liquid state from said liquid product tank 8, if necessary, evaporation of the main product 10, if necessary, transfer of said main product to a main gaseous product tank 9, in a recovery circuit 12: evaporation of liquid product in said liquid product tank 8 to obtain a recovery product in the gaseous state, transfer of said recovery product to a thermal compressor 13, in said thermal compressor 13, compression of said recovery product at least in part by raising the temperature of said recovery product or of an intermediate agent such as a metal hydride, using a cold source and a hot source,said cold source receiving cold energy from said main circuit 10, where appropriate, transferring the recovery product compressed by said thermal compressor 13 to said main gaseous product tank 9 or to a gaseous product recovery tank 9.,

[0065] As mentioned above, it is advantageous to use in the present invention a multi-stage type thermal compressor 13 as illustrated in FIGS. 10.

[0066] In the present application, the expression "multi-stage thermal compressor" is used exclusively to describe a thermal compressor of the type described below, and illustrated in 10. The multi-stage thermal compressor 13, illustrated in 10, comprises an upstream source 1, a target 2, and one or more groups of reservoirs 3.

[0067] The multi-stage thermal compressor 13 allows gas to be compressed from an upstream source 1, at which the gas is at a pressure P0, to a pressure P cible . In the present invention, the gas compressed by the multi-stage thermal compressor 13 is the recovery product.

[0068] The tanks 3 are capable of containing a certain volume of said gas in a sealed manner. Within a group, the tanks 3 all preferably have the same volume, for example 50 liters.

[0069] The multi-stage thermal compressor 13 comprises a heating means 4 and a cooling means 5 for the contents of each tank 3. The heating means 4 recovers thermal energy, or calories, from a hot source, and the cooling means 5 recovers cold energy, or frigories, from a cold source. The heating 4 and cooling 5 means make it possible, for example, to bring a heat transfer fluid into contact with the contents of each tank 3. If the heat transfer fluid is hotter, or colder, respectively, than the contents of a tank 3, it can be used to heat, or cool, said contents, respectively.

[0070] The heating means 4 can also be an electrical resistor immersed in the tank.

[0071] The heat source of the multi-stage thermal compressor 13, or any other type of thermal compressor 13 used in the present invention, may be connected to an electrolyzer or a biomass dihydrogen production unit. Thus, if the gas is dihydrogen, the heat generated to produce this dihydrogen may be recovered in the thermal compressor 13. Depending on the installation location of the multi-stage thermal compressor 13, other locally available waste heat sources may constitute the heat source to reduce the costs of the energy consumed. This may be, for example, a waste collection site, or any other industrial site in which heat is produced.

[0072] The multi-stage thermal compressor 13 also comprises transfer means 6a for transferring gas directly from the upstream source 1 to each reservoir 3 of a group, and transfer means 6b for transferring gas directly from each reservoir 3 of a group to the target 2. A direct transfer here designates a transfer which does not pass through another reservoir 3 of the same group or of another group, nor through the upstream source 1 or the target 2.

[0073] The multi-stage thermal compressor 13 finally comprises bidirectional transfer means 7 for transferring gas directly from each tank of a group to each other tank of the same group. A direct transfer here designates a transfer which does not pass through another tank 3 of the same group or of another group, nor through the upstream source 1 or the target 2. Thus, considering any pair of tanks 3 of the same group, it is possible to transfer gas directly between these two tanks 3, in both directions.

[0074] The multi-stage thermal compressor 13 can be used according to a cyclic method of thermal compression of a gas in a plurality of reservoirs 3 of at least one group. Each cycle comprises for each reservoir 3a of each group the following steps: cooling of the gas contained in the reservoir 3a, to a cold temperature T1, and transfer of gas from the upstream source 1 to said reservoir 3a. At the end of this step, the reservoir 3a contains gas at a pressure P0 and a temperature T1. transfer of gas from another donor reservoir 3 to said reservoir 3a. The donor reservoir 3 is the one whose gas is at the lowest pressure among the reservoirs 3 of the same group whose gas is at a pressure and a temperature higher than the gas contained in said reservoir 3a.The transfer takes place automatically when the bidirectional transfer means 7 between the reservoir 3a and the donor reservoir 3 is opened, until the pressures in the reservoir 3a and the donor reservoir 3 are equalized. It is during this step that the gas contained in said reservoir 3a is compressed. At the end of the first occurrence of this step, the reservoir 3a contains gas at a pressure P1 and a temperature T1. This step can be repeated several times, as long as there is another reservoir 3 in said group whose gas is at a higher pressure and temperature than the gas contained in said reservoir 3a. The step can for example be repeated twice if the group comprises three reservoirs 3, or three times if the group comprises four reservoirs 3. Each repetition of this step allows the reservoir 3a to increase a pressure stage. At the end of this step, the reservoir 3a contains gas at a pressure P. Kand a temperature T1, with K equal to the number of repetitions of the transfer step. heating of the gas contained in the tank 3a, to a hot temperature T2, which makes it possible to raise a final pressure stage, and transfer of gas from said tank 3a to the target 2. At the end of this step, the tank 3a contains gas at a pressure P K+1 and a temperature T2. The pressure P K+1 is close to, or equal to, the pressure P cible.transfer of gas from said tank 3a to another receiving tank 3. The receiving tank 3 is the one whose gas is at the highest pressure among the tanks 3 of the same group whose gas is at a pressure and temperature lower than the gas in said tank 3a. The transfer takes place automatically upon opening the bidirectional transfer means 7 between the tank 3a and the receiving tank 3, until the pressures in said tank 3a and said receiving tank 3 are equalized. At the end of the first occurrence of this step, the tank 3a contains gas at a pressure close to or equal to P Kand a temperature T2. This step can be repeated several times, as long as there is another tank 3 of said group whose gas is at a pressure and temperature lower than the gas of tank 3a. The step can for example be repeated twice if the group has three tanks 3, or three times if the group has four tanks 3. Each repetition of this step allows tank 3a to raise another tank 3 of the same group a pressure stage. At the end of this step and its repetition to the end, tank 3a contains gas at a pressure close to or equal to P1 and a temperature T2.

[0075] In the case where all the reservoirs 3 of the group have an identical volume, the quantity of gas in the reservoir 3 can also be determined at each stage:at the end of the cooling and transfer stage from the upstream source 1, the reservoir 3a contains n0moles of gas,at the end of one occurrence of the transfer stage from a donor reservoir 3 to said reservoir 3a, said reservoir 3a contains n1moles of gas,at the end of the entire transfer stage from one or more donor reservoirs 3 to said reservoir 3a, said reservoir 3a contains n K moles of gas, at the end of the heating and transfer step to target 2, reservoir 3a contains n K-1 moles of gas, at the end of an occurrence of the step of transferring said reservoir 3a to a receiving reservoir 3, said reservoir 3a contains n K-2 moles of gas, at the end of the entire step of transferring said reservoir 3a to one or more receiving reservoirs, said reservoir 3a contains n -1moles of gas.

[0076] The step of cooling the gas contained in the tank and transferring gas from the upstream source 1 to said tank 3a is carried out successively for each tank 3 of said group, and not for several tanks 3 at the same time. Thus the tanks 3 of the group each pass through this step in turn, then follow the same cycle simultaneously, each with a time lag compared to the others.

[0077] During this process, the thermal compression of the gas is done by opening the transfer means between two reservoirs 3, the reservoir 3 in which the gas is the most compressed allowing the gas in the other reservoir 3 to increase in pressure. The reservoir 3 which receives the gas is in a cold state and the reservoir 3 which gives the gas is in a hot state. This allows that with an equivalent number of moles of gas in the two reservoirs 3, the hot reservoir 3 has a higher pressure and can give gas and increase the pressure in the cold reservoir 3. During each cycle, each reservoir 3 thus goes through a pressure increase in a cold state, then a pressure decrease in a hot state. During a cycle followed by a reservoir 3, it therefore only needs to be heated and cooled once.

[0078] Preferably, during the step of transferring gas from another tank 3 of the same group whose gas is at a higher pressure and temperature to said tank 3, the transferred gas is cooled. This makes it possible to maintain a cold temperature in the tank 3 which receives the hot gas, and thus to maintain the temperature differential with the other hot tanks 3. The transferred gas may be cooled before its arrival in the tank 3, for example in the bidirectional transfer means 7 between the two tanks 3. Alternatively, the transferred gas may be cooled after its arrival in the tank 3, by cooling the entire contents of the tank 3, for example by the cooling means 5. In a preferred embodiment of the invention, the contents of a tank 3 cooled to the cold temperature T1 are kept at the cold temperature T1 until the heating step.Similarly, the contents of a tank 3 heated to the hot temperature T2 are preferably kept at the hot temperature T2 until the cooling step. This makes it possible to always benefit from the temperature differential between T1 and T2 when connecting a hot tank 3 to a cold tank 3 to increase the pressure of the latter.

[0079] In order to optimize the cycle of the process for using the multi-stage thermal compressor 13, at least two steps of the process can be carried out simultaneously. A first step includes a gas transfer between a first and a second entity, these two entities being the upstream source 1 and a reservoir 3, two reservoirs 3, or a reservoir 3 and the target 2, and a second step includes a gas transfer between a third and a fourth entity, these two entities being the upstream source 1 and a reservoir 3, two reservoirs 3, or a reservoir 3 and the target 2. The first, second, third and fourth entities being four distinct entities.

[0080] For example, the step of transferring gas from the upstream source 1 to a first reservoir 3a, …, 3h takes place simultaneously with the step of transferring gas from a second reservoir 3a, …, 3h to a receiving reservoir 3 or to the target 2. Thus when certain reservoirs 3 of the multi-stage thermal compressor 13 carry out certain steps, other reservoirs 3 carry out other steps of the process, which saves time.

[0081] In a preferred embodiment of the invention, in order to optimize the energy consumption of the method of using the multi-stage thermal compressor 13, during the step of cooling the gas contained in a first tank 3a, …, 3h, it is possible to use heat extracted from said first tank 3a, …, 3h in the step of heating the gas contained in a second tank 3a, …, 3h. For example, a heat transfer fluid can be circulated from the first tank 3a, …, 3h to the second tank 3a, …, 3h.

[0082] A group of tanks 3 comprises at least two tanks 3, for example three, preferably four tanks 3. The choice of the number of tanks 3 is made, with the other parameters of the multi-stage thermal compressor 13, according to the number of stages necessary to compress the gas from the pressure P0 at the upstream source 1 to the pressure P cibledesired to target 2. Other parameters to be adjusted include the volumes of tanks 3, and the temperatures T1 and T2 at which tanks 3 are heated and cooled. It is advantageous to have an even number of tanks 3 in a group. This allows that at each process step, one of the process steps takes place in each tank 3.

[0083] The multi-stage thermal compressor 13 may comprise a single group of reservoirs 3, preferably it comprises two groups of reservoirs 3. Indeed, the total number of steps in the cycle described above, counting the repetitions of the second and fourth steps, is equal to twice the number of reservoirs 3 in a group. When the multi-stage thermal compressor 13 comprises a single group, only half of the steps can therefore be carried out at the same time by one of the reservoirs 3. The steps of transferring gas from the upstream source 1 and to the target 2, in particular, do not take place for a single group at each stage of the cycle. It may therefore be provided to have two groups operating in parallel, which makes it possible to have, at each stage of the cycle, gas transferred from the upstream source 1 to one of the reservoirs 3 of the multi-stage thermal compressor 13, and from one of the reservoirs 3 of the multi-stage thermal compressor 13 to the target 2.The number of tanks in each group can be different, but in order to achieve the above-mentioned advantage for two groups, it is necessary that both groups have either an even or an odd number of tanks.

[0084] According to a particular embodiment of the multi-stage thermal compressor 13, additional reservoirs 3 may be provided to enable heating and cooling to be carried out in several stages. This is advantageous if the heating and cooling stages take longer than the transfer stages; typically if these stages take twice as long as the transfer stages, it may be advantageous to carry out heating and cooling in two stages.

[0085] According to another particular embodiment of the multi-stage thermal compressor 13, it is possible to provide an installation which operates initially between a first source pressure P0 and a target pressure P1. Then, in a second stage, a portion of the gas at pressure P1 can be taken and made into a source at pressure P1. The device then raises the pressure to a pressure P2. This can continue for as long as necessary to finally reach the target pressure.

[0086] In order to optimize energy consumption, the temperature of the cold source, and therefore of cooling T1, can be as low as possible, i.e. for example the ambient temperature or the temperature of the lowest cold source available at the site of use.

[0087] The 13 multi-stage thermal compressor is particularly advantageous for small installations, with a gas output flow rate at target 2 for example between 1 and 100 kg per hour.

[0088] Illustrates an exemplary embodiment of the multi-stage thermal compressor 13 in which it comprises a group of two reservoirs 3a, 3b. The volumes of the reservoirs 3a, 3b are equal. In the, the arrows illustrate the gas flows. The state of each reservoir is noted after the gas transfers are completed.

[0089] The cycle has four stages: stage A: the gas contained in reservoir 3a is heated to temperature T2 and part of this gas is transferred to target 2. At the end of this stage, reservoir 3a contains n0moles of gas, at pressure P2= P cible, and at temperature T2. the gas contained in the tank 3b is cooled to the temperature T1 and gas is transferred from the upstream source 1 to the tank 3b. At the end of this step, the tank 3b contains n0moles of gas, at pressure P0, and at temperature T1. step B: the bidirectional transfer means 7 is opened between the tanks 3a and 3b, which causes a transfer of gas from the tank 3a to the tank 3b. At the end of this step, the tank 3a contains n -1 moles of gas, at pressure P1, and at temperature T2, and reservoir 3b contains n1 moles of gas, at pressure P1, and at temperature T1.

[0090] Steps C and D are identical to steps A and B, with the tanks 3a and 3b swapped. After step D, the cycle can resume at step A.

[0091] Figures 9 and 10 illustrate an exemplary embodiment in which the multi-stage thermal compressor 13 has two groups of four reservoirs 3a to 3d and 3e to 3h. The volumes of reservoirs 3a to 3d are equal. The volumes of reservoirs 3e to 3h are equal. In Figures 9 and 10, the arrows illustrate the gas flows. The state of each reservoir is noted after the gas transfers are completed.

[0092] The cycle consists of eight steps A to H. We will describe the cycle followed by the tank 3a: step A: the gas contained in the tank 3a is cooled to the temperature T1 and gas is transferred from the upstream source 1 to the tank 3a. At the end of this step, the tank 3a contains n0moles of gas, at pressure P0, and at temperature T1, step B: the bidirectional transfer means 7 is opened between the tanks 3a and 3b, which causes a transfer of gas from the tank 3b to the tank 3a. At the end of this step, the tank 3a contains n1moles of gas, at pressure P1, and at temperature T1. step C: the bidirectional transfer means 7 is opened between the tanks 3a and 3d, which causes a transfer of gas from the tank 3d to the tank 3a. At the end of this step, reservoir 3a contains n2moles of gas, at pressure P2, and at temperature T1.step D: the bidirectional transfer means 7 is opened between the reservoirs 3a and 3c, which causes a transfer of gas from the reservoir 3c to the reservoir 3a. At the end of this step, the reservoir 3a contains n3moles of gas, at pressure P3, and at temperature T1. step E: the gas contained in the reservoir 3a is heated to the temperature T2 and a part of this gas is transferred to the target 2. At the end of this step, the reservoir 3a contains n2moles of gas, at pressure P4= P. cible, and at temperature T2.step F: the bidirectional transfer means 7 is open between the reservoirs 3a and 3b, which causes a transfer of gas from the reservoir 3a to the reservoir 3b. At the end of this step, the reservoir 3a contains n1moles of gas, at pressure P3, and at temperature T2.step G: the bidirectional transfer means 7 is open between the reservoirs 3a and 3d, which causes a transfer of gas from the reservoir 3a to the reservoir 3d. At the end of this step, the reservoir 3a contains n0moles of gas, at pressure P2, and at temperature T2.step H: the bidirectional transfer means 7 is open between the reservoirs 3a and 3c, which causes a transfer of gas from the reservoir 3a to the reservoir 3c. At the end of this step, the reservoir 3a contains n -1 moles of gas, at pressure P1, and at temperature T2. At the end of step H, the cycle can resume at step A.

[0093] All reservoirs 3a to 3h follow the above cycle, exchanging of course with the relevant reservoirs 3 at each transfer step: reservoir 3b starts the above cycle at step C, reservoir 3c starts the above cycle at step G, reservoir 3d starts the above cycle at step E, reservoir 3e starts the above cycle at step B, reservoir 3f starts the above cycle at step D, reservoir 3g starts the above cycle at step H, reservoir 3h starts the above cycle at step F,

[0094] The presence of two groups in the multi-stage thermal compressor 13 makes it possible here to have, during each stage of the cycle, a reservoir 3 receiving gas from the upstream source 1 and a reservoir 3 sending gas to the target 2. Indeed, for example, in stage A it is the reservoir 3d of the first group of reservoirs 3 which sends gas to the target 2, in stage B it is the reservoir 3h of the second group of reservoirs 3, then in stage C the reservoir 3c of the first group of reservoirs 3, and so on. Furthermore, in stage A it is the reservoir 3a, of the first group of reservoirs 3, which receives gas coming from the upstream source 1, in stage B it is the reservoir 3e of the second group of reservoirs 3, then in stage C the reservoir 3b of the first group of reservoirs 3, and so on.

[0095] Considering this example of implementation, and carrying out the heating and cooling steps over the duration of two transfer steps, this leads to providing ten tanks 3 instead of eight. The ten tanks then constitute a single group, and each tank 3 can be connected to three other tanks 3 among the ten, by bidirectional transfer means; each tank 3 must of course also be connected to the source and the target by transfer means.

[0096] Although the above description is based on particular embodiments, it is in no way limiting of the scope of the invention, and modifications may be made, in particular by substitution of technical equivalents or by different combination of all or part of the characteristics developed above.

Claims

A product transformation system, said product being in a gaseous state when at a pressure of 1 bar and a temperature of 283K, said system comprising: at least one liquid product reservoir (8), a main circuit (10) configured to extract a liquid primary product from the liquid product reservoir, and a recovery circuit (12) comprising at least one thermal compressor (13) configured to compress a gas at least in part by raising the temperature of said gas or of an intermediate agent such as a metal hydride, by means of a cold source and a hot source, and transfer means for transferring a recovery product resulting from evaporation inside the liquid product reservoir (8) to one of said at least one thermal compressor (13), the cold source of at least one of said thermal compressors (13) being configured to receive cold energy from said main circuit (10). A product transformation system according to the preceding claim, wherein the main circuit (10) comprises at least one evaporator (11) and transfer means for transferring a main product in liquid form from the liquid product reservoir (8) to one of said at least one evaporator (11). System according to the preceding claim, wherein said cold source of at least one of said at least one thermal compressor (13) comprises a cold circuit (14) configured to be traversed by a heat transfer fluid thermally connected to said evaporator (11). System according to any one of the preceding claims, wherein said cold source of at least one of said at least one thermal compressor (13) comprises a cold circuit (14) configured to be traversed by said main product. System according to any one of the preceding claims, wherein the hot source of at least one of said at least one thermal compressor (13) is thermally connected to the ambient air. System according to any one of the preceding claims, wherein the recovery circuit comprises: at least one first thermal compressor (13), the cold source of which is configured to receive cold energy from said main circuit (10) and the hot source is thermally connected to the ambient air, and downstream of said at least one first thermal compressor (13) with respect to the movement of said second gaseous product, at least one second thermal compressor (13), the cold source of which is configured to receive cold energy from said main circuit (10) or from the ambient air and the hot source is thermally connected to a waste heat source or to an electric heater. A system according to any one of the preceding claims, wherein at least one of said at least one thermal compressor (13) is a multi-stage thermal compressor (13) comprising an upstream source (1), a target (2), and at least one group of tanks (3), each comprising at least two tanks (3), said thermal compressor (13) further comprising a heating means (4) and a cooling means (5) for the contents of each tank (3), said heating means being connected to said hot source and said cooling means being connected to the cold source, each group further comprising: transfer means (6a, 6b) for transferring gas directly from said upstream source (1) to each tank (3) and directly from each tank (3) to said target (2), and for each tank (3) of said group,bidirectional transfer means (7) for transferring gas directly between this tank (3) and at least one other tank (3) of said group. A process for transforming a product contained in a liquid product reservoir (8), said product being a product that is in a gaseous state when at a pressure of 1 bar and a temperature of 283K, said process comprising the following steps: in a main circuit (10): extraction of a main product in a liquid state from said liquid product reservoir (8), in a recovery circuit (12): evaporation of the liquid product in said liquid product reservoir (8) to obtain a recovered product in a gaseous state, transfer of said recovered product to at least one thermal compressor (13), in said at least one thermal compressor (13), compression of said recovered product at least in part by raising the temperature of said recovered product or of an intermediate agent such as a metal hydride, by means of a cold source and a hot source,said cold source receiving cold energy from said main circuit (10). A process according to the preceding claim, further comprising, in the main circuit (10), after the extraction step, an evaporation step of said main product. A method according to any one of claims 8 to 9, wherein the temperature of the liquid product in the liquid product reservoir (8) is less than 123 K. A method according to any one of claims 8 to 10, wherein the pressure of the gaseous product downstream of said at least one thermal compressor (13) is greater than or equal to 300 bar. A method according to any one of claims 8 to 11, wherein said compression of the recovered product is carried out at least in part by a cyclic thermal compression process of a gas in a plurality of tanks (3), each cycle comprising, for each tank (3a, …, 3h) of said plurality of tanks (3), the following steps: cooling of the gas contained in the tank (3a, …, 3h) and transfer of gas from an upstream source (1) to said tank (3a, …, 3h), transfer of gas from a donor tank (3) to said tank (3a, …, 3h), said donor tank (3) being at a pressure and temperature higher than the gas in said tank (3a, …, 3h) and of the same group, preferably said donor tank (3) being the one whose gas is at the lowest pressure among the tanks (3) of said group whose gas is at a pressure and temperature higher than the gas in said tank (3a, …, 3h), until equalization of the pressures in said reservoir (3a, …,3h) and said donor tank (3), if applicable, repetition of this step as long as there is another tank (3) of said group whose gas is at a higher pressure and temperature than the gas of said tank (3a, …, 3h), heating of the gas contained in the tank (3a, …, 3h) and transfer of gas from said tank (3a, …, 3h) to a target (2), transfer of gas from said tank (3a, …, 3h) to a receiving tank (3), said receiving tank (3) being at a lower pressure and temperature than the gas of said tank (3a, …, 3h), preferably said receiving tank (3) being the one whose gas is at the highest pressure among the tanks (3) of said group whose gas is at a lower pressure and temperature than the gas of said tank (3a, …, 3h), until equalization of the pressures in said tank (3a, …, 3h) and said receiving tank (3), if applicable,repetition of this step as long as there is another tank (3) of said group whose gas is at a pressure and temperature lower than the gas of said tank (3a, …, 3h), the step of cooling the gas contained in the tank (3a, …, 3h) and transferring gas from the source to said tank (3a, …, 3h) being carried out successively for each tank (3) of said group.

Images