System for producing steam for a high-temperature electrolyzer comprising an absorption machine and method for treatment of a fluid such as water

Abstract

The invention relates to the preheating of a supply fluid for a high-temperature electrolyzer (6) using a system (1) comprising an absorption heat transformer (12).

Description

STEAM PRODUCTION SYSTEM FOR HIGH-TEMPERATURE ELECTROLYSER INCLUDING AN ABSORPTION MACHINE AND A METHOD FOR TREATMENTING A FLUID SUCH AS WATER

[0001] The present invention relates to the field of industrial heat production techniques, particularly in the form of steam.

[0002] The invention is of particular interest for hydrogen production facilities by vapor phase electrolysis, also called "high temperature electrolysis", which may typically require water vapor with a temperature between 600°C and 850°C. State of the art

[0003] Vapor phase electrolysis technologies, particularly solid oxide electrolyzers known by the Anglo-Saxon name "Solid Oxide Electrolysis Cell (SOEC)", classically use steam produced by generators that use electricity or fossil fuels as an energy source.

[0004] There is a need to reduce the environmental impact of such technologies, as well as the cost of hydrogen production.

[0005] The invention relates to a system for treating a first fluid, comprising: a first circuit configured to convey said first fluid from an inlet of the system to an outlet of the system, a second circuit configured to convey a second fluid from a heat source, a heat exchanger connected to the first circuit and to the second circuit in order to be able to transfer heat from said second fluid to said first fluid, an absorption heat transformer comprising an absorber connected to said first circuit in order to be able to transfer heat generated by the absorber to said first fluid.

[0006] The first fluid in question could be water.

[0007] The second fluid can be a heat transfer fluid such as water.

[0008] Without limitation, the system may be intended to process said first fluid in order to supply an electrochemical device, in particular a high-temperature electrolyzer to produce hydrogen.

[0009] The invention makes it possible to utilize a source of waste heat, particularly when it has a temperature below 100°C, while increasing the heat input to said first fluid.

[0010] The use of waste heat typically reduces the system's electrical consumption by approximately 15% to preheat the first fluid when it is used to power the electrochemical device.

[0011] When the system is used to power an electrochemical device, the invention thus makes it possible to reduce the need to use ancillary techniques, for example an electric boiler, to finalize the conditioning of said first fluid at the inlet of the electrochemical device.

[0012] In addition, an absorption heat transformer, or absorption machine, makes it possible to produce heat with lower electrical consumption, especially compared with conventional heat pumps, and can be implemented with fluids that do not contribute to the destruction of the ozone layer or the increase of the greenhouse effect.

[0013] The invention thus makes it possible to recover waste heat, particularly at low temperature, to power the absorption machine, which can then be used to preheat the water needed for the electrolysis reaction of an electrolyzer to a temperature that is higher than that which would be obtained by directly recovering the waste heat source with a heat exchanger.

[0014] In one embodiment, the first circuit includes a conduit connecting the heat exchanger and the absorber to each other in order to convey said first fluid from the heat exchanger to the absorber.

[0015] In one embodiment, the first circuit includes a conduit connecting the heat exchanger to a condenser of the transformer in order to convey said first fluid from said condenser to the heat exchanger.

[0016] In one embodiment, the transformer includes a generator connected to the second circuit in order to transfer heat from said second fluid to said generator.

[0017] In one embodiment, the transformer includes an evaporator connected to the second circuit in order to be able to transfer heat from said second fluid to said evaporator.

[0018] In one embodiment, the second circuit includes a conduit connecting the heat exchanger and the generator to each other in order to convey said second fluid from the generator to the heat exchanger.

[0019] In one embodiment, the second circuit includes a conduit connecting the heat exchanger and the evaporator to each other in order to convey said second fluid from the evaporator to the heat exchanger.

[0020] In one embodiment, the system includes a means for cooling the condenser.

[0021] Without limitation, said cooling means may include a component of the system such as an air heater and / or an external source such as a water table or a river.

[0022] The invention also relates to an installation comprising a system as defined above and an electrochemical device.

[0023] In one embodiment, the electrochemical device includes a high-temperature electrolyzer.

[0024] The said system output is preferably fluidly connected to an input of the electrochemical device.

[0025] In one embodiment, the installation includes the aforementioned heat source, that is, the source from which said second fluid originates.

[0026] In one embodiment, said heat source is a waste heat source rejected at a temperature below 120°C, preferably below 110°C, more preferably below 100°C.

[0027] This waste heat can be released by an agri-food industry, a paper and cardboard industry, a chemical industry, a waste incinerator, a data center, or even a wastewater treatment plant.

[0028] The invention also relates to a method for treating a fluid such as water, in particular said first fluid, using a system as defined above.

[0029] The process includes a step of transferring heat generated by the absorber of the system's transformer to the fluid, in particular to said first fluid.

[0030] Alternatively or in addition, depending on the embodiment, the process may include one or more of the following steps: heat transfer of said second fluid to said first fluid using said heat exchanger, and / or heat transfer of said second fluid to said generator, and / or heat transfer of said second fluid to said evaporator, and / or cooling of said condenser using said cooling means.

[0031] According to a first variant, the process can be implemented to treat said fluid in order to supply an electrochemical device of an installation as defined above.

[0032] According to a second variant, the process can be implemented to treat said fluid in order to provide industrial steam.

[0033] Regardless of the use of the fluid treated by the system of the invention, the process can be implemented to change or not the state of the fluid.

[0034] Thus, according to a first alternative, the process can be implemented to increase the temperature of said fluid while maintaining it in a liquid state.

[0035] According to a second alternative, the process can be implemented to increase the temperature of said fluid by changing it from a liquid to a gaseous state.

[0036] Other advantages and features of the invention will become apparent from the detailed, non-limiting description that follows. Brief description of the figures

[0037] The detailed description that follows refers to the accompanying drawings in which: 1 schematically illustrates a system configured to thermally treat a fluid such as water using an external heat source; 2 schematically shows an installation, comprising a system such as that of 1 and an electrochemical device supplied by the fluid treated by the system; 3 is a schematic view of a system such as that of 1, in an embodiment in which the system comprises a heat exchanger and an absorption machine, each configured to transfer thermal energy to the fluid to be treated; 4 is a schematic view of an absorption machine comprising a generator, a condenser, an evaporator, an absorber, a heat exchanger, two pumps, an expansion valve and fluid circuits, forming a single-effect absorption heat transformer;This is a schematic view of an installation comprising, on the one hand, a system such as that of the [system name], this system integrating an absorption machine as illustrated in the [system name], and, on the other hand, an electrochemical device supplied by the fluid treated by the system.

[0038] Common references are used across the different figures to designate identical or analogous elements. Detailed description of implementation methods

[0039] With reference to the aforementioned, the invention generally relates to a system 1 for treating a first fluid, in particular for raising the temperature of this first fluid, using heat contained in a second fluid. The system 1 comprises, for this purpose, a fluid circuit 2 for introducing the second fluid into the system 1, and a fluid circuit 3 for extracting the first fluid from the system 1.

[0040] In the non-limiting embodiment illustrated in Figure 1, system 1 of the invention is implemented within an installation 5 which is equipped with an electrochemical device 6 for the production of hydrogen. The invention is, of course, not limited to the production of hydrogen.

[0041] Circuit 3 of installation 5 is configured to establish fluid communication between an output of system 1 and an input of device 6, in order to introduce into device 6 the said first fluid treated by system 1.

[0042] In this example, the electrochemical device 6 comprises solid oxide electrolytic cells for carrying out vapor-phase electrolysis, forming a technology known as a "Solid Oxide Electrolysis Cell." As is known per se, such an electrolyzer 6 comprises one or more stacks of cells, each forming a cathode, an anode, and an electrolyte, thus constituting a reaction zone.

[0043] In the example shown, device 6 is configured to perform high-temperature electrolysis in order to produce hydrogen from the first fluid. For illustrative purposes, in the section of circuit 3 connecting the outlet of system 1 to the inlet of device 6, this fluid typically consists of water vapor at a temperature between 100°C and 850°C.

[0044] In an alternative implementation of the invention, not shown, the system of the invention may form, or be part of, an installation lacking such an electrochemical device. For example, system 1 of the invention may be used as an industrial heat production unit.

[0045] In the examples presented here, the second fluid is a heat transfer fluid carrying heat from a source which is preferably an industrial waste heat source.

[0046] More specifically and without limitation, the second fluid can transport waste heat at a temperature below 100°C, which can typically be discharged by a food processing industry, a paper and cardboard industry, a chemical industry, a waste incinerator, a data center, or a wastewater treatment plant.

[0047] Lamontre a system 1 conforming to the invention, which can be implemented in the installation 5 of the, or in a different installation.

[0048] In the embodiment of the, the system 1 includes a heat exchanger 11, an absorption machine 12, conduits 2A and 2B forming circuit 2 to convey said second fluid, in this example from a waste heat source, and conduits 3A, 3B and 3C forming circuit 3 which is configured to convey said first fluid.

[0049] The heat exchanger 11 is connected to circuits 2 and 3 in such a way as to be able to transfer heat from said second fluid to said first fluid.

[0050] In the description that follows, the terms "upstream" and "downstream" are used with reference to a direction of fluid flow when system 1 is in operation.

[0051] In the example of the, a downstream end of conduit 2A is fluidly connected to a first inlet of the heat exchanger 11, an upstream end of conduit 2B is fluidly connected to a first outlet of the heat exchanger 11, a downstream end of conduit 3A is fluidly connected to a second inlet of the heat exchanger 11, and an upstream end of conduit 3B is fluidly connected to a second outlet of the heat exchanger 11.

[0052] Without limitation, the heat exchanger 11 and the circuits 2 and 3 are configured here to circulate the first fluid and the second fluid in counter-current flow within the exchanger 11. Of course, in an alternative embodiment not shown, the heat exchanger 11 and the circuits 2 and 3 can be configured to circulate the first fluid and the second fluid in co-current flow within the exchanger 11.

[0053] With reference to the, a downstream end of conduit 3B is fluidly connected to an inlet of machine 12, while an upstream end of conduit 3C is fluidly connected to an outlet of machine 12.

[0054] System 1 thus allows the introduction into machine 12 of the said first fluid after it has recovered part of the heat transported by the said second fluid.

[0055] Lamontre an absorption machine 12 that can be implemented in a system according to the invention, in particular in system 1 of figures 1 to 3.

[0056] Machine 12 is a thermal machine operating in heat production mode which is classically called an "absorption heat transformer", or "absorption heat transformer" ("Absorption Heat Transformer" in English).

[0057] With reference to the, the machine 12 comprises a generator 21, a condenser 22, an evaporator 23, an absorber 24, an internal heat exchanger 25, an expansion valve 26, two pumps 27 and 28, as well as internal fluid circulation conduits 31, 32, 33, 34, 41, 42, 43, 51, 52 and 53, forming in a manner known per se a single-effect absorption heat transformer.

[0058] More specifically, in this example, the conduits 31 to 34 are configured to circulate a refrigerant from the generator 21 to the absorber 24, via the condenser 22, the pump 28 and the evaporator 23. The conduits 41 to 43 and 51 to 53 form a circuit configured to circulate a refrigerant-absorbent solution between the absorber 24 and the generator 21, via the exchanger 25, the expansion valve 26 and the pump 27 (see).

[0059] By way of example, the refrigerant can be ammonia and the absorbent can be water.

[0060] In a manner known as such, the generator 21 generates refrigerant vapor at relatively low pressure, thanks to a thermal energy input 61. The condenser 22 condenses this vapor, releasing thermal energy 62, typically to the atmosphere. The pump 28 increases the refrigerant pressure to a relatively high level, where it is evaporated by the evaporator 23 under the action of a thermal energy input 63. The refrigerant vapor exiting the evaporator 23 is conveyed to the absorber 24 via the conduit 34 to be absorbed into the refrigerant-absorbent solution. This exothermic absorption generates thermal energy 64, providing a useful heat source, and reduces the concentration of the solution from the conduit 53 from a relatively high to a relatively low concentration of absorbent, with the absorbent-rich solution exiting the absorber 24 through the conduit 41.The expansion valve 26 lowers the pressure of the solution exiting the absorber 24 before its introduction into the generator 21. The solution exiting the generator 21 through the conduit 51, which has been enriched in absorbent within the generator 21, is compressed by the pump 27 before its introduction into the absorber 24. The heat exchanger 25 allows heat transfer between the solution rich in absorbent and the solution poor in absorbent in the circuit formed by the conduits 41-43 and 51-53.

[0061] Of course, the invention can be implemented using a machine different from the one illustrated in the figure. By way of non-limiting example, machine 12 can be without the internal heat exchanger 25.

[0062] Ingeniously, the thermal energy 64 produced at the absorber 24 of the machine 12 can be transferred to a fluid, in particular said first fluid when the machine 12 is implemented in a system as described above with reference to Figures 1 to 3, for example as illustrated in the embodiment of the.

[0063] Lamontre an installation 5 conforming to the invention, combining the principles described above with reference to figures 1 to 4.

[0064] In this particular example, installation 5 comprises a system 1 and an electrolyzer 6 coupled to each other according to the principle illustrated in Figure 1. System 1 of this installation 5 comprises a heat exchanger 11 and an absorption chiller 12 coupled to each other according to the principle illustrated in Figure 1. The absorption chiller 12 of installation 5 is similar to that of Figure 1.

[0065] It is understood that the entire preceding description applies by analogy to the embodiment of the, which is described below mainly in order to specify coupling modes which do not appear directly on figures 1 to 4.

[0066] With reference to the above, circuit 2 includes the aforementioned conduits 2A and 2B as well as conduits 2C1, 2C2 and 2D. Circuit 3 includes the aforementioned conduits 3A, 3B and 3C, as well as conduits 3D, 3E and 3F.

[0067] Installation 5 also includes a 70 air heater.

[0068] The ducts 3E and 3F are configured to circulate said first fluid between the condenser 22 and the air heater 70 so as to transfer to the air heater 70 the thermal energy 62 produced by the condenser 22, which allows the condenser 22 to be cooled.

[0069] The 3D conduit is configured to introduce the first fluid into system 1, specifically at conduit 3E. In this example, the first fluid comes from a relatively cold source. For reference, the first fluid can arrive in conduit 3D at a temperature ranging from 0°C to 30°C, for example, a temperature of around 15°C.

[0070] An upstream end of the duct 3A is fluidically connected to an outlet of the condenser 22 in order to convey part of the first fluid to the heat exchanger 11, within which its temperature is increased (see corresponding description).

[0071] Without limitation, the condenser 22 may include a plate heat exchanger or a shell and tube type heat exchanger.

[0072] Regarding circuit 2 of installation 5, in this example, conduits 2C1 and 2C2 are both configured to carry the second fluid, originating from a waste heat source, to their downstream end. For illustrative purposes, the second fluid may arrive in conduits 2C1 and 2C2 at a temperature between 60°C and 100°C, for example, a temperature of approximately 80°C.

[0073] The downstream end of conduit 2C1 is fluidically connected to an inlet of evaporator 23, while an upstream end of conduit 2A is fluidly connected to an outlet of evaporator 23, so that the second fluid can provide evaporator 23 with the necessary thermal energy input 63 for its operation.

[0074] The downstream end of conduit 2C2 is fluidically connected to an inlet of generator 21, while an upstream end of conduit 2D is fluidly connected to an outlet of generator 21, so that the second fluid can supply generator 21 with the thermal energy input 61 necessary for its operation.

[0075] A downstream end of the 2D conduit is fluidically connected to said first inlet of the heat exchanger 11.

[0076] In the example shown, the thermal energy 64 rejected at the level of the absorber 24 is used to increase the temperature of the first fluid passing through the absorber 24 via the conduits 3B and 3C. The absorber 24 is thus connected to the circuit 3 in order to transfer heat 64 to the said first fluid.

[0077] Two non-limiting operating modes of installation 5 will now be described.

[0078] In each of these operating modes, the first fluid is water which is introduced into system 1 at a temperature of around 15°C, the second fluid is water introduced into system 1 with a temperature of around 80°C, and the first fluid exits system 1 at a temperature of around 105°C in order to produce the electrolysis reaction in device 6.

[0079] In the first mode of operation, the installation 5 is implemented so that the fluid exiting system 1 through conduit 3C is in a liquid state, the fluid being vaporized within the device 6. In other words, system 1 is configured to preheat the first fluid by maintaining it in a liquid state.

[0080] This first mode of operation can typically be implemented when device 6 is a relatively high power electrolyzer, consuming in this example a maximum of 0.83 kg of water per second and requiring a power of 2.2 MW to obtain sufficient water temperature and pressure for the electrolysis reaction.

[0081] The inventors estimated that in this first mode of operation, the absorption machine 12 transfers 0.318 MW of power to the water, or 15% of the total power required, and achieves a thermal coefficient of performance (COP) of 0.79 and an electrical COP of 12.4. By comparison, an installation using only a heat exchanger in a similar configuration would transfer 0.153 MW of power to the water, or only 6% of the total power required.

[0082] In the second operating mode, installation 5 is implemented so that the fluid exiting system 1 through conduit 3C is in a gaseous state. In other words, system 1 is configured to preheat the first fluid by changing it from a liquid to a gaseous state.

[0083] This second mode of operation can typically be implemented when device 6 is a relatively low power electrolyzer, consuming in this example a maximum of 0.1 kg of water per second and requiring a power of 0.27 MW to obtain sufficient water temperature and pressure for the electrolysis reaction.

[0084] The inventors estimated that in this second operating mode, the absorption machine 12 transfers 0.264 MW of power to the water, or 98% of the total power required, and achieves a thermal COP of 0.61 and an electrical COP of 5.3. By comparison, an installation using only a heat exchanger in an analogous configuration would transfer 0.019 MW of power to the water.

[0085] These examples illustrate the possibility of preheating the feedwater of electrolyzer 6 from 15°C to 105°C, with or without phase change, using the absorption chiller 12 powered by an 80°C heat source. In addition to the increase in the final temperature of the preheated water, the addition of such an absorption chiller 12 allows for the transfer of significantly more power from the source to the feedwater of electrolyzer 6, compared to an installation comprising only a heat exchanger utilizing a waste heat source at 80°C. The data provided above indicate that the invention increases the power transferred by approximately twofold in the case of a high-power electrolyzer and by approximately fourteenfold in the case of a low-power electrolyzer.The invention thus makes it possible to reduce the consumption of electrical energy since an increase in the amount of power transferred reduces the amount of electrical energy needed to finalize the conditioning of the feed water.

[0086] The preceding description is not limiting; numerous variations could be envisaged within the scope of the invention. For example, the absorption machine could use a refrigerant and absorption fluid pair H2O-LiBr instead of NH3-H2O.

[0087] For other, non-limiting examples, the air heater 70 of installation 5 can be replaced by another means of cooling the condenser 22, in particular by an abundant external cooling source such as groundwater or river water. It is thus possible to eliminate the air heater 70 and further improve the energy performance of the installation, typically increasing the electrical COP tenfold.

Claims

System (1) for treating a first fluid, such as water, comprising: a first circuit (3) configured to convey said first fluid from an inlet of the system (1) to an outlet of the system (1), a second circuit (2) configured to conduct a second fluid from a heat source, a heat exchanger (11) connected to the first circuit (3) and to the second circuit (2) in order to be able to transfer heat from said second fluid to said first fluid, an absorption heat transformer (12) comprising an absorber (24) connected to said first circuit (3) in order to be able to transfer heat (64) generated by the absorber (24) to said first fluid. System (1) according to claim 1, wherein the first circuit (3) comprises a conduit (3B) connecting the heat exchanger (11) and the absorber (24) to each other in order to convey said first fluid from the heat exchanger (11) to the absorber (24). System (1) according to claim 1 or 2, wherein the first circuit (3) comprises a conduit (3A) connecting the heat exchanger (11) to a condenser (22) of the transformer (12) in order to convey said first fluid from said condenser (22) to the heat exchanger (11). System (1) according to any one of claims 1 to 3, wherein: the transformer (12) comprises a generator (21) connected to the second circuit (2) in order to be able to transfer heat (61) from said second fluid to said generator (21), and / or the transformer (12) comprises an evaporator (23) connected to the second circuit (2) in order to be able to transfer heat (63) from said second fluid to said evaporator (23). System (1) according to any one of claims 1 to 4, wherein: the second circuit (2) comprises a conduit (2D) connecting the heat exchanger (11) and the generator (21) to each other in order to convey said second fluid from the generator (21) to the heat exchanger (11), and / or the second circuit (2) comprises a conduit (2A) connecting the heat exchanger (11) and the evaporator (23) to each other in order to convey said second fluid from the evaporator (23) to the heat exchanger (11). System (1) according to any one of claims 1 to 5, comprising a means (70) for cooling the condenser (22), said cooling means (70) comprising an element of the system (1) such as an air heater and / or an external source such as a water table or a river. Installation (5) comprising a system (1) according to any one of claims 1 to 6 and an electrochemical device (6) such as a high-temperature electrolyzer, said output of the system (1) being fluidly connected to an input of the electrochemical device (6). Installation (5) according to claim 7, comprising said heat source from which said second fluid originates, this heat source preferably being a waste heat source discharged at a temperature below 100°C, for example by a food processing industry, a paper and cardboard industry, a chemical industry, a waste incinerator, a data center, or a wastewater treatment plant. Method of treating a fluid such as water using a system (1) according to any one of claims 1 to 6, for example to supply an electrochemical device (6) of an installation (5) according to claim 7 or 8, or to supply industrial steam, the method comprising a step of transferring to the fluid heat generated by the absorber (24) of the transformer (12) of the system (1). A method according to claim 9, wherein the system (1) is configured to increase the temperature of said fluid by maintaining it in a liquid state, or by changing it from a liquid state to a gaseous state.

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