Saltwater evaporator and high-temperature electrolysis system therewith

Abstract

The present invention relates to a saltwater evaporator (1) comprising a housing (10), which substantially encloses an inner space (11) having at least one steam outlet opening (12) and has at least a first saltwater feed (11a), wherein the surface of the inner space (11) and the first saltwater feed (11a) are designed to allow saltwater (A), as a saltwater film (B), to run off along the vertical axis (Z) on the surface of the inner space (11), and comprising at least one heat source (16, 17), which is designed and arranged within the inner space (11) in order to contactlessly heat the side of the saltwater film (B) which faces away from the surface of the inner space (11) and faces the heat source (16, 17) in such a way that exactly one part of the liquid phase of the saltwater film (B) is evaporated, wherein the housing (10) further comprises at least one saltwater outlet (11c) of the inner space (11), which is arranged and formed along the vertical axis (Z) below the first saltwater feed (11a) to carry off the rest of the liquid phase of the saltwater film (B) out of the inner space (11).

Description

[0001] DESCRIPTION

[0002] Salt water evaporator and high-temperature electrolysis plant

[0003] The invention relates to a salt water evaporator and a high-temperature electrolysis plant with such a salt water evaporator.

[0004] Hydrogen can play an important role as a secondary energy carrier in the development of a sustainable energy economy, provided the hydrogen can be obtained from renewable energy sources. Hydrogen can be used in fuel cells to generate electricity. Hydrogen can also replace existing fossil fuels.

[0005] In any case, hydrogen production plays a major role here. Hydrogen can be produced in a variety of ways. Currently, electrolysis is the primary method used to produce "green" hydrogen, with the required electrical energy being generated using renewable energy sources.

[0006] With regard to electrolysis, there are various processes depending on the application and boundary conditions. They use an electrolyzer with the help of an electric current which brings about a chemical reaction, i.e. a material transformation, i.e. electrolysis takes place. Depending on the operating principle, different types of electrolysis or electrolyzer are known, such as proton exchange membrane electrolysis (PEM electrolysis), in which ultrapure water is split into hydrogen and oxygen using an electric current. High-temperature electrolysis is also well known, which requires high operating temperatures, for example of around 900 °C, since part of the necessary reaction enthalpy is coupled in as heat. This reduces the power required for electrolysis and thus increases the efficiency compared to other types of electrolysis. With high-temperature electrolyzers, efficiencies of up to approx.90% based on the calorific value can be achieved.

[0007] All electrolysis processes have in common that water (H2O) is split into hydrogen (H2) and oxygen (O2) in the electrolysis plant. Ultrapure water is required for this process. In high-temperature electrolysis, the water is required in the form of steam or superheated steam as the process product. The disadvantage or problem with any form of electrolysis is that "clean" water, in the sense of ultrapure water, is required as a starting material for the electrolysis in order to achieve the splitting of the water into hydrogen and oxygen without other substances previously dissolved in the water remaining as deposits in the electrolyzer after the splitting process and contaminating it. This can impair its functionality, reduce its efficiency, and, over time, cause damage or even failure of the electrolyzer.

[0008] These problems arise particularly when saltwater, which is a solution of salts in water, is used as the starting material for electrolysis. The average salinity of the oceans is 3.5%. Therefore, if electrolysis is carried out using saltwater, salt or table salt remains in the electrolyzer as a deposit and can adhere to the surface, causing the disadvantages and problems described above.

[0009] In principle, however, salt water could be used for electrolysis in general, and especially for the aforementioned high-temperature electrolysis. By combining a salt water-fed steam generator with a high-temperature electrolyzer, a salt water-based electrolysis system or high-temperature electrolysis plant with an overall efficiency of almost 65% can be realized, although the overall efficiency is highly dependent on the efficiency of the high-temperature electrolyzer.

[0010] A saltwater-fed steam generator is therefore useful where there is generally little "clean" water available and (hot) steam is required in large quantities, and where condensation of the steam is not possible for certain reasons, such as the escape of the steam into the atmosphere or the conversion of the steam into other gases (e.g., 2 H2O -> 2 H2 + O2).

[0011] Since deposits during the evaporation of salt water represent a significant problem, previously known electrolyzers, particularly those used for steam generation using a steam generator in high-temperature electrolysis, use only pretreated water, which, if possible, contains no other components than hydrogen and oxygen. Desalting salt water first to then use it as pure water for electrolysis would involve too much effort and, in particular, energy consumption to be economically and ecologically viable. Thus, the use of salt water as a liquid for steam generation for subsequent electrolysis has so far been uncommon.

[0012] WO 2012 / 027823 A1 describes a method and apparatus for generating high-purity, high-temperature steam from non-pure water, such as brackish water, salt water, seawater, and the like, which can be used in a variety of industrial processes involving high-temperature heat applications. During operation, the process can be carried out continuously.

[0013] Molten salt, which serves as a heat source, is introduced into an inner chamber of the heat exchanger steam generator. At the same time, impure water is introduced as a spray and a continuous stream into an outer chamber, which is fluid-tightly separated from the inner chamber by a wall and surrounds the inner chamber in a cylindrical manner. As the molten salt is forced downward through the inner, central chamber by the rotation of a screw, heat is transferred across the common wall to the impure water entering the outer chamber.

[0014] The height of the device is selected to ensure sufficient heat transfer to generate high-temperature steam from the impure water. To this end, boiling water is generated in a lower part of the outer chamber, which rises upwards and becomes high-temperature steam, which is discharged through an outlet.

[0015] As steam is formed from the impure water, impurities and salts settle at the bottom of the outer chamber. This can be a solid precipitate or a slurry, or both. These substances are removed by a suitable means, for example, using an extruder in the device.

[0016] A disadvantage of the method and device described in WO 2012 / 027823 A1 is, firstly, that the technical complexity of the implementation is not insignificant due to the fluid-tight separation of the inner, central chamber and the outer chamber, resulting in corresponding manufacturing costs. The use of molten copper chlorine (CuCl) salt also results in significant operating costs.

[0017] Both have an impact on the production costs and the price of the high-temperature steam produced.

[0018] Another disadvantage is that the impure water at the bottom of the outer chamber must first form a reservoir to be heated or boiled sufficiently to achieve the phase transition to steam. This also increases the effort and time required for the process.

[0019] Another disadvantage is that impurities and salts from the impure water are deposited at the bottom of the outer chamber, which must be removed with considerable effort, especially during the ongoing process in order not to interrupt it.

[0020] DE 2407 080 A1 describes a method and apparatus for recovering dissolved solids from aqueous solutions by introducing the solution into the upper region of a thin-film evaporator, allowing the solution to drain over the inner walls of the evaporator, and blowing a hot combustion gas stream downward between the wet walls. The apparatus comprises vertical walls forming an evaporator chamber, an outlet line in the lower region of the evaporator chamber, an inlet opening for feeding the liquid phase, and a distributor in the upper region of the evaporator chamber. The distributor distributes the aqueous solution containing the solids in the evaporator such that the solution flows evenly and continuously downward over the inner walls of the evaporator chamber and finally leaves the chamber through the outlet line.and with centrally arranged means for supplying the combustion gas in the upper region of the evaporator chamber, so that a stream of hot combustion gases can be jetted downwards into the chamber, in such a way that this hot gas stream is guided at a certain distance from the wetted walls and is only in contact with them by direct thermal radiation, and wherein the hot combustion gases from the supply or the burner also leave the evaporator chamber through the outlet line. This device has a flow-restricting Venturi design on the outlet line, which sets the liquid phase in the lower region of the chamber above the outlet into a swirling motion. This swirling motion of the liquid phase causes turbulent mixing of the hot combustion gases with the solution, thus causing rapid evaporation of the water and precipitation of the solids.

[0021] Since the objective of the method and device of DE 2407080 A1 is to recover dissolved solids from aqueous solutions and thus to achieve the most complete and rapid evaporation of the water in the solution, the method and device of DE 2407080 A1 is not applicable to the evaporation of salt water to generate steam for known electrolyzers, in particular for steam generation using a salt water-fed steam generator in high-temperature electrolysis, since the steam generated by the method and device of DE 2407 080 A1 always contains impurities in the combustion gas. The desired mixing between the hot gas and the liquid phase, which benefits particularly good heat transfer, but which leads to the introduction of impurities from the combustion gas into the steam during evaporation of the aqueous solutions, represents precisely the invention of DE 2407 080 A1.

[0022] One object of the present invention is to improve the possibilities for generating pure steam from salt water and the like, something otherwise only possible with ultrapure water. In particular, the possibilities for evaporating salt water and the like to generate pure steam for electrolysis in general and, in particular, to generate pure superheated steam for high-temperature electrolysis are to be improved. In any case, this should be as simple, cost-effective, low-maintenance, flexible in use and / or space-saving as possible. At the very least, an alternative to the known possibilities is to be created. This object is achieved according to the invention by a salt water evaporator and by a high-temperature electrolysis system having the features of the independent patent claims. Advantageous further developments are described in the subclaims.

[0023] Thus, the present invention relates to a salt water evaporator comprising a housing which substantially encloses an interior space with at least one steam outlet opening and has at least one first salt water supply, wherein the surface of the interior space and the first salt water supply are designed to allow salt water to drain as a salt water film along the vertical axis at the surface of the interior space, and comprising at least one heat source which is designed and arranged within the interior space to contactlessly heat the side of the salt water film facing away from the surface of the interior space, which side faces the heat source, such that exactly a portion of the liquid phase of the salt water film is evaporated, wherein the housing further comprises at least one salt water outlet of the interior space, which is arranged and designed along the vertical axis below the first salt water supply,to remove the remaining part of the liquid phase of the salt water film from the interior.

[0024] "Salt water" is understood to mean not only salt water, but especially brackish water and seawater, but also any other liquid containing solids, contaminants, minerals, and the like, which remain in the remaining part of the liquid when part of the liquid evaporates. Thus, a "salt water evaporator" within the meaning of the present invention refers to any device capable of evaporating salt water, brackish water, sea water, and similar liquids in accordance with the other features of the salt water evaporator according to the invention, i.e., converting them from the liquid phase to the gaseous phase or from the liquid state to the gaseous state.

[0025] According to the invention, however, not all of the salt water is evaporated, but deliberately only a portion of it, so that the solids, minerals, and contaminants that are or may be contained in the salt water remain there and can be removed from the salt water evaporator with the non-evaporated portion of the salt water. This can, on the one hand, enable the generation of pure steam from salt water and, on the other hand, prevent the deposition of solids, minerals, and contaminants in the interior of the salt water evaporator.

[0026] Specifically, this is achieved according to the invention by utilizing gravity to allow the salt water to drain from the surface or inside of the interior of the saltwater evaporator as a film, i.e., as a thin, flat distribution of saltwater, and to expose this flat distribution to the heat of the heat source without contact. The formation of the saltwater film can be achieved or influenced by the formation of the first saltwater supply and the surface of the interior, as will be explained in more detail below.

[0027] In this way, according to the invention, that part of the salt water film which is in contact with the surface of the interior of the salt water evaporator can run continuously from the first salt water inlet into the salt water outlet, and thus solids or minerals, contaminants and the like can always be entrained there and removed from the interior of the salt water evaporator. At the same time, this part of the salt water film can cool the surface of the interior of the salt water evaporator. That part of the salt water film which faces the heat source can be evaporated simultaneously, i.e. during the flowing movement on the surface of the interior of the salt water evaporator along the vertical direction towards the salt water outlet, so that the desired pure vapor can be generated.

[0028] This can preferably be achieved by a cylindrical design of the surface of the interior of the saltwater evaporator, so that the heat source, such as in particular the flame of a hydrogen burner, can be oriented centrally and axially upwards or downwards along the vertical axis, and the saltwater film can be formed as evenly as possible in the circumferential direction around the heat source. This can increase the surface area of ​​the interior of the saltwater evaporator and thus the area of ​​evaporation of the saltwater film.

[0029] If the surface of the interior of the saltwater evaporator is preferably designed to taper downwards, this downward taper can ensure that, due to the continuously decreasing circumference around the vertical axis, the amount of saltwater, which also continuously decreases due to evaporation, is distributed over an ever-smaller area of ​​the surface of the interior of the saltwater evaporator, so that, despite evaporation, a saltwater film with as constant a thickness as possible can be created. This can ensure the formation of the flowing part of the saltwater film with simultaneous evaporation of the remaining part of the saltwater film, as described above, in a simple, purely structural manner, all the way to the saltwater outlet of the interior.

[0030] Preferably, a saltwater film that is as consistently constant as possible can be achieved or influenced additionally or alternatively by the operation of the heat source. For this purpose, the heat source can be adjusted with regard to the intensity of the generated warmth or heat by a corresponding control unit, which can be controlled or regulated, i.e., by adjusting it to a reference variable. In particular, the size, in particular the extension along the vertical axis, of the flame of a hydrogen burner can be controlled or regulated in order to influence the heating or vaporizing effect of the hydrogen flame on the outer surface of the saltwater film facing the hydrogen flame.

[0031] According to one aspect of the invention, the heat source comprises an electric heating element, an infrared heating element, and / or an inductive heating element. Preferably, the heat source is an electric heating element, an infrared heating element, and / or an inductive heating element. These can be various options, including contactless or non-contact heating.

[0032] Evaporation of a portion of the liquid or salt water without contaminating it or the resulting vapor. These options can also be used in combination with each other or with a hydrogen burner, as described in more detail below.

[0033] According to a further aspect of the invention, the electric heating element is arranged along the vertical axis above the first saltwater supply on the housing by means of a fastening, preferably by means of a suspension, and extends from the fastening into the interior without contact along the vertical axis. This can represent a concrete implementation possibility for arranging the electric heating element in a contactless manner but at the same time as close as possible to the saltwater film, in particular extending along the vertical axis largely parallel to the saltwater film.

[0034] According to a further aspect of the invention, the heat source comprises a hydrogen burner, preferably the heat source is a hydrogen burner. Thus, the heat or warmth for evaporating a portion of the salt water can be generated by combustion, with hydrogen being burned as fuel. This has the particular advantage that the combustion produces only water vapor, which is the result of the evaporation of the salt water film and thus corresponds to the starting product of the salt water evaporation. Heating or evaporating the salt water film by means of a hydrogen burner or a hydrogen flame can thus reliably prevent contamination of the steam or superheated steam to be generated.

[0035] This also applies if the hydrogen burner primarily burns a hydrogen-water-oxidizer mixture. The addition of water during the combustion process can cool the hydrogen flame and thus regulate the combustion process or reduce its temperature, as is known, for example, from German patent application 10 2023 106 528.9 (unpublished).

[0036] According to a further aspect of the invention, the hydrogen burner is designed and arranged to generate a burner flame, preferably an H2-O2 (H2O) burner flame, directed upwards or downwards along the vertical axis. This presents possibilities for influencing the evaporation or the degree of evaporation. For example, an upwardly directed burner flame can have a further extension along the vertical axis and thus achieve a comparatively long overlap with a heating effect compared to the draining salt water film with comparatively little burning fuel, since the flame rises upwards of its own accord. This can also improve the heat transfer between the salt water film and the generated steam. A downwardly directed burner flame can improve steam mixing to homogenize the temperature distribution.

[0037] According to a further aspect of the invention, the interior space, at least in the area of ​​contactless heating by the heat source, preferably from the first saltwater supply point, is conically shaped along the vertical axis, tapering downwards toward the saltwater outlet. This allows the corresponding properties and advantages described above to be specifically implemented and realized.

[0038] According to a further aspect of the invention, the housing has a plurality of first saltwater inlets, which are preferably arranged at the same height along the vertical axis and / or evenly spaced perpendicular to the vertical axis. This can promote or achieve the most uniform possible formation of the saltwater film, as described above, particularly starting from the first saltwater inlets. This allows the corresponding properties and advantages described above to be specifically implemented and realized.

[0039] According to a further aspect of the invention, the housing has a second saltwater inlet between the first saltwater inlet and the saltwater outlet, preferably approximately centrally, which is also designed to allow saltwater to drain off as a saltwater film along the vertical axis on the surface of the interior. This allows the saltwater film to be refilled, so to speak, and thus ensures the formation of the flowing part of the saltwater film. The loss or shrinkage of the thickness of the saltwater film due to evaporation can thus be compensated by further saltwater exiting through the second saltwater inlet. This also allows the thinnest possible saltwater film to be created in the area above the second saltwater inlet, which is so thin that the saltwater film created by the first saltwater inlet

[0040] Salt water outlet would not reach the surface at all or at least not as a continuous salt water film, which can be achieved or ensured by filling or feeding the salt water film created by the first salt water supply with additional salt water by means of the second salt water supply.

[0041] According to a further aspect of the invention, the housing has a plurality of guide channels extending along the vertical axis towards the interior, preferably as far as the saltwater outlet of the interior, and preferably decreasing in depth. This allows the amount of salt water draining from the saltwater film to be increased without increasing its thickness, which can promote the formation of a saltwater film that is as thin as possible but flows continuously. Reducing the depth of the guide channels along the vertical axis can cause saltwater to pass from there into the saltwater film along the guide channels and compensate for the evaporated liquid there, which can promote a saltwater film that is as consistently constant as possible.

[0042] According to a further aspect of the invention, the heat source is designed to be positioned relative to the housing, preferably by means of a lifting drive, along the vertical axis. This can provide a way to influence the heating effect of the heat source, in particular as a hydrogen burner, by altering the overlap, particularly radially aligned, between the saltwater film running down the surface of the interior and the heat source, in particular its hydrogen flame. This can provide a further way to influence the degree of evaporation of the saltwater film.

[0043] According to a further aspect of the invention, the interior space along the vertical axis in the region between the first saltwater inlet and the saltwater outlet is formed at least in sections, preferably substantially, particularly preferably almost entirely, by a rotatable housing part of the housing, wherein the rotatable housing part of the housing is designed to be driven in rotation relative to the housing about the vertical axis, preferably by means of a rotary drive. As a result, the draining saltwater film can be set in rotation, which can lead to an oblique or spiral flow of the draining saltwater film. This can increase the effective distance along which the draining saltwater film is exposed to heating. The speed of the rotation can be specifically adjusted, in particular controlled or regulated, in order to influence the evaporation.This can provide another way to influence the rate of evaporation of the saltwater film. The slanted wall and its rotation can also create a buoyancy force in the water, which counteracts gravity. This can reduce the downward flow velocity of the water.

[0044] According to a further aspect of the invention, the salt water evaporator is designed to partially return the steam discharged from the interior through the steam outlet opening to the interior by means of a steam return system, preferably conveyed by a steam pump. This allows steam return to be implemented in order to utilize the generated steam as completely as possible and to keep it in the circuit of the salt water evaporator. When using a hydrogen burner, this can reduce the temperature of the outer flame zone in order to prevent the evaporation of undesirable substances such as salts. According to a further aspect of the invention, the salt water evaporator is designed to operate the interior under increased pressure, wherein the steam outlet opening is preferably followed by a steam throttle and / or wherein the first salt water supply preferably has a salt water pump. This can represent a further possible implementation.This allows hot steam or superheated steam to be generated under pressure due to the increased pressure, which can be advantageous or necessary for some applications such as high-temperature electrolysis.

[0045] According to a further aspect of the invention, the saltwater outlet is followed by a saltwater collector, preferably with a saltwater throttle, which is designed to collect and drain the escaping saltwater. This can enable targeted removal of the excess liquid portion of the saltwater film. The saltwater collector can also serve to vapor-tightly seal the saltwater outlet. If the interior of the saltwater evaporator is operated under excess pressure, this can be compensated for by a saltwater throttle behind the saltwater outlet. However, a saltwater throttle can also be used during normal operation to ensure an appropriate water level, which can provide the aforementioned vapor-tightness.

[0046] The present invention also relates to a high-temperature electrolysis plant with at least one saltwater evaporator as described above. In this way, the saltwater evaporator according to the invention, or the steam or superheated steam generated thereby, can be used within a high-temperature electrolysis plant to implement the properties and advantages of a saltwater evaporator according to the invention.

[0047] In other words, the evaporator according to the invention should make it possible to evaporate salt water and thus provide process steam.

[0048] By using an H2-O2 (H2O) burner to provide the energy, a process can be developed that enables stable operation. The evaporation of a "salt water film" using the H2-O2 (H2O) flame is advantageous because the flame provides hot steam, thus allowing for steam-based evaporation.

[0049] Evaporation thus occurs at the surface of the saltwater film, i.e., at the interface between steam and water. This creates several advantages:

[0050] • Minimal start-up time for the device, as no large mass needs to be heated up, as with a conventional steam generator; • When using an H2-O2 (H2O) flame, the exhaust gases from the flame correspond to the desired product;

[0051] • no deposits on the walls of the evaporator chamber caused by evaporation, since the phase transition takes place on the water surface.

[0052] The goal, or rather a key aspect, of the present invention is to evaporate a portion of the saltwater film while simultaneously allowing the remaining saltwater film to flow continuously and parallel to the heat source, in particular to the H2-O2 (H2O) flame. This minimizes the mixing of the two phases of the saltwater film, but rather merely transfers energy across the contact surface to the heat source, leading to the phase transition of a portion of the liquid phase. Because only a portion of the saltwater is evaporated, the undesirable components of the water are flushed out of the system with the unevaporated saltwater.

[0053] In order to meet the very high purity requirements of the steam, the geometry design can be used to create a flow field that, on the one hand, creates good mixing of the steam phase in order to achieve the most efficient heat transfer possible (homogeneous temperature field in the gas phase) and, on the other hand, transfers so little momentum, especially in the contact areas between steam and liquid, that droplet detachment or particle detachment from the water film does not occur.

[0054] To ensure that there are no problems in the event of a droplet being entrained, the inlet and outlet lines for the salt water and steam can be designed in such a way that droplet separation, substance detachment, substance separation, and particle separation, respectively, are likely. In the configuration with the steam outlet at the top of the evaporator chamber, this process is gravity-assisted. In the configuration with a burner at the top and a steam outlet at the bottom, this process is achieved through a significant flow deflection, whereby droplets or other components with a higher density than the desired steam are separated due to inertial forces.

[0055] The structural design explained below can also result in further advantages such as:

[0056] • almost no thermal stress on the combustion chamber walls due to the cooling of the combustion chamber walls by the salt water film;

[0057] • Excess water can be used to remove "evaporation residues" in the form of enriched salt water. The technical solution involves the use of gravity, which is why an upright arrangement of the evaporator is necessary. Heat is generated via a heat source acting contactlessly on the outer surface of the salt water film, such as the previously mentioned H2-O2 (H2O) burner.

[0058] It is advantageous to use methods or devices that prevent deposits on the water-contacting components of the evaporator or its chamber, since disruptive deposits can form over time even without the evaporation process. This can be achieved, for example, using ultrasonic vibrations.

[0059] Preferably, energy or heat is introduced into the system via an H2O2 (H2O) flame in the center of the steam generator. This heat is used to evaporate some of the salt water that is fed into the combustion chamber at the top. If necessary, it is useful to integrate additional water supply lines distributed along the system.

[0060] Preferably, the combustion chamber walls can be arranged at a slight angle, allowing the salt water to flow down the surface in a controlled manner, while also allowing the geometry to expand slowly enough to prevent steam or exhaust gas from separating from the combustion chamber walls. To ensure even water distribution, the combustion chamber wall can be equipped with additional small guide channels.

[0061] The steam production rate can be influenced by the amount of water supplied and by a movable burner head. If the steam needs to be hotter, less steam is produced overall (power remains virtually constant). The temperature increase is achieved by "raising" the burner head, so that the burner head is moved further into the combustion chamber to reduce the heat transfer surface. Conversely, if a larger amount of cooler steam is required, the burner can be moved back to the beginning or exit of the combustion chamber.

[0062] To further increase the efficiency of the steam generator, additional heat exchangers can be used, allowing the residual heat from the returning water to be used to preheat the reactants. Preheating can also be achieved, for example, using waste heat from other processes.

[0063] It can also be operated at higher pressure to utilize the stored pressure change energy for downstream processes. For this purpose, a suitable pump for salt water extraction can be connected, and the gases can be made available at the appropriate pressure. Furthermore, the water backflow can be adjusted using a throttle valve and aligned with the steam backpressure.

[0064] Another option is to install the burner from above. This can potentially improve steam mixing (to homogenize the temperature distribution). However, this can create a uniform flow between steam and water, which can lead to poorer heat transfer between steam and water.

[0065] Another possible way to generate steam is to replace the H2-O2 (H2O) burner with an electrical heat source. In this setup, evaporation can be achieved using an electrically heated core, but this can lead to a significantly reduced power density (steam production per volume) due to the comparatively low heat input into the system. This variant can also exhibit significantly slower control behavior overall compared to the previously described H2-O2 (H2O) burner due to its high mass.

[0066] In any case, the temperature can be influenced, controlled, or regulated by the operation of the heat source or its parameters, particularly by a corresponding control unit, especially the evaporator. To optimize the evaporation process, the "right" temperature range can be sought to avoid the undesirable evaporation of solids (e.g., salts). The temperature range can depend heavily on the salt water used. The temperature can be influenced by the heat source or the H2-O2 (H2O) burner, on the one hand, and controlled by vapor recirculation (i.e., product recirculation), on the other.

[0067] In any case, the invention is based on the realization that steam is required by industry both for process heat and as process steam for technical applications. Steam generators used previously simply require freshwater or even specially treated water, depending on the application. In contrast, the invention is capable of generating steam from saltwater. The field of application is diverse but primarily influenced by local conditions. Thus, the use of saltwater-based steam makes sense wherever fresh water is generally limited. The primary application could be the provision of steam to supply large-scale high-temperature electrolyzers. Furthermore, this type of evaporation generally allows for the construction of significantly more compact steam generators (even from previously treated water).

[0068] Several exemplary embodiments and further advantages of the invention are illustrated and explained in more detail below in conjunction with the following figures. Figure 1 shows a schematic cross-section through a saltwater evaporator according to the invention according to a first exemplary embodiment;

[0069] Figure 2 shows a schematic cross section through a salt water evaporator according to the invention according to a second embodiment;

[0070] Figure 3 shows a schematic cross section through a salt water evaporator according to the invention according to a third embodiment;

[0071] Figure 4 shows a schematic cross section through a salt water evaporator according to the invention according to a fourth embodiment;

[0072] Figure 5 shows a schematic cross section through a salt water evaporator according to the invention according to a fifth embodiment;

[0073] Figure 6 shows a schematic cross section through a salt water evaporator according to the invention according to a sixth embodiment;

[0074] Figure 7 shows a schematic cross section through a salt water evaporator according to the invention according to a seventh embodiment;

[0075] Figure 8 shows a schematic cross section through a salt water evaporator according to the invention according to an eighth embodiment; and

[0076] Figure 9 is a schematic representation of a high-temperature electrolysis plant according to the invention with a salt water evaporator according to the invention according to the eighth embodiment.

[0077] The above figures are viewed in Cartesian coordinates. A longitudinal axis (not shown) extends, which can also be referred to as depth or length. Perpendicular to the longitudinal axis is a transverse axis Y, which can also be referred to as width Y. Perpendicular to both the longitudinal and transverse axes Y is a vertical axis Z, which can also be referred to as height Z and corresponds to the direction of gravity. The longitudinal axis and the transverse axis Y together form the horizontal, which can also be referred to as the horizontal plane.

[0078] Figure 1 shows a schematic cross section through a salt water evaporator 1 according to the invention according to a first embodiment.

[0079] The saltwater evaporator 1 has a housing 10, which can also be referred to as a casing 10. The housing 10 extends essentially along the vertical axis Z. The housing 10 forms or essentially encloses an interior space 11, which can also be referred to as an evaporator chamber 11 and extends in the circumferential direction (not designated) around the vertical axis Z. The upper region of the interior space 11, which is comparatively short along the vertical axis Z, is tapered upwards and opens at the top into a steam outlet opening 12, through which steam D generated in the interior space 11 can escape to the outside of the housing 10. From the lower edge of this cone (not designated), a surface, also tapered, extends downwards along the vertical axis Z as the surface or inner surface (not designated) of the interior space 11.This inner surface of the interior space 11 extends along the vertical axis Z significantly longer than the upper conical surface, so that the inner surface of the interior space 11 has a comparatively small gradient. The inner surface of the interior space 11 opens downwards into a saltwater outlet 11c, which simultaneously forms a burner opening 11d.

[0080] At the transition between the two conical surfaces, a plurality of first, upper salt water inlets 11a are arranged as through-openings or bores through the housing 10, evenly spaced from one another in the circumferential direction, each of which is connected from the outside to a salt water connection (not designated) in order to allow salt water A to reach the interior 11. During operation of the salt water evaporator 1, the salt water A is guided or conveyed through the first salt water inlets 11a into the interior 11 at a sufficiently low level or with low pressure, so that the salt water A runs down the surface or inner surface of the interior 11 as a salt water film B.The first salt water inlets 11a are arranged so close to one another in the circumferential direction around the vertical axis Z that, as far as possible, a salt water film B which is closed in the circumferential direction is formed from the first salt water inlets 11a and runs down the surface of the interior space 11 in a closed manner towards the salt water outlet 11c.

[0081] Below the salt water outlet 11c, a salt water collector 13 is arranged as a box or basin to collect the salt water A and discharge it via a salt water drain 13a.

[0082] A heat source 16, 17 in the form of a hydrogen burner 16 projects from below into the interior 11 of the housing 10 along the vertical axis Z through the saltwater collector 13 and through the saltwater outlet 11c or through the burner opening 11d. From below or outside the saltwater collector 13, the hydrogen burner 16 is supplied with oxygen (O2) by means of an oxygen (O2) supply 16a, with hydrogen (H2) by means of a hydrogen (H2) supply 16b, and with water (H2O) by means of a water (H2O) supply 16c. Oxygen and hydrogen can be burned and the heat of combustion can be regulated by means of the water, so that an H2-O2-H2O burner flame C extends from the exit or outlet of the hydrogen burner 16 along the vertical axis Z into the interior 11 almost to the first salt water inlets 11a.

[0083] The H2-O2-H2O burner flame C, which thus runs parallel to the salt water film B, can evaporate a portion of the salt water film B running down the surface of the interior space 11 during operation, so that steam D rises upwards and can exit the interior space 11 through the steam outlet opening 12. At the same time, the salt water film B can continue to flow downwards, thus carrying or removing the minerals and impurities from the salt water A, so that they neither enter the steam D nor adhere to the surface of the interior space 11 and contaminate it. Due to the use of an H2-O2-H2O burner flame C, their components cannot contaminate the steam D. Thus, according to the invention, "pure" or clean steam D can be obtained from salt water A.

[0084] Figure 2 shows a schematic cross-section through a saltwater evaporator 1 according to the invention according to a second exemplary embodiment. The saltwater evaporator 1 according to the second exemplary embodiment corresponds to the saltwater evaporator 1 according to the first exemplary embodiment, with the addition that additional second, middle saltwater inlets 11b are arranged approximately centrally along the vertical axis Z between the first, upper saltwater inlets 11a and the saltwater outlet 11c in order to supply additional saltwater A comparable to the first saltwater inlets 11a and to compensate for the losses of the saltwater A already evaporated.

[0085] Figure 3 shows a schematic cross-section through a saltwater evaporator 1 according to the invention according to a third exemplary embodiment. The saltwater evaporator 1 according to the third exemplary embodiment corresponds to the saltwater evaporator 1 according to the second exemplary embodiment, with the addition that the hydrogen burner 16 can be moved or variably positioned to a certain extent along the vertical axis Z. For this purpose, the hydrogen burner 16 can be moved up and down along the vertical axis Z by means of a lifting drive 15.

[0086] Figure 4 shows a schematic cross-section through a salt water evaporator 1 according to the invention in a fourth exemplary embodiment. The salt water evaporator 1 according to the fourth exemplary embodiment corresponds to the salt water evaporator 1 according to the first exemplary embodiment, with the addition that the housing 10 is divided into a vertical housing part 10a and a rotatable housing part 10b. The vertical housing part 10a ends along the vertical axis Z slightly below the first salt water inlets 11a and extends from there cylindrically projecting radially outwards, in order to run radially again at the level of the salt water outlet 11c and to terminate there above the salt water collector 13, so that a fluid-tight volume is still created between the first salt water inlets 11a and the salt water outlet 11c. The rotatable cylindrical housing part 10b is arranged within this volume and forms the remaining orforms the essential part of the surface or inner surface of the interior space 11 in order to create an interior space 11 or a surface or inner surface of the interior space 11 as in the other embodiments.

[0087] The rotatable housing part 10b is mounted relative to the stationary housing part 10a, both upwards and downwards, along the vertical axis Z by means of bearings 10c in the form of ball bearings or the like. The volume region between the cylindrical stationary housing part 10a and the cylindrical rotatable housing part 10b can be referred to as the antechamber 11e. A rotary drive 14 is arranged in the antechamber 11e to drive the rotatable housing part 10b and thereby set it in a rotary motion, which can also set the flowing salt water film B in rotation. This can lengthen the distance that the salt water film B must travel to reach the salt water outlet 11c, thus increasing the time during which the heating of the H2-O2-H2O burner flame C can act on the salt water film B and partially evaporate it. This can thus increase or influence the evaporation.The conically tapered surface of the interior space 11 and its rotation can also generate a buoyancy force of the saltwater film B, which acts counter to gravity. This can reduce the downward flow velocity of the saltwater film B along the vertical axis Z.

[0088] Figure 5 shows a schematic cross-section through a saltwater evaporator 1 according to the invention according to a fifth exemplary embodiment. The saltwater evaporator 1 according to the fifth exemplary embodiment corresponds to the saltwater evaporator 1 according to the second exemplary embodiment, with the difference that in this case the hydrogen burner 16 protrudes from above along the vertical axis Z into the interior 11, which can lead to improved steam mixing due to a homogenization of the temperature distribution. Accordingly, the burner opening 11d in this case is arranged at the upper end of the housing 10. The steam outlet opening 12 is correspondingly arranged in the lower region of the housing 10, specifically on the side.

[0089] Figure 6 shows a schematic cross-section through a saltwater evaporator 1 according to the invention according to a sixth exemplary embodiment. The saltwater evaporator 1 according to the sixth exemplary embodiment corresponds to the saltwater evaporator 1 according to the first exemplary embodiment, with the difference that in this case an electrical heating element 17 is used as the heat source 16, 17, which can be electrically powered to emit heat or thermal radiation. The electrical heating element 17 is attached along the vertical axis Z above the first saltwater inlets 11a to the upper conical surface by means of several suspensions 17a and projects from there along the vertical axis Z downwards into the interior 11 up to near the saltwater outlet 11c. Thus, contactless evaporation of the saltwater film B to vapor D can also take place in this way.

[0090] Figure 7 shows a schematic cross-section through a saltwater evaporator 1 according to the invention according to a seventh exemplary embodiment. The saltwater evaporator 1 according to the seventh exemplary embodiment corresponds to the saltwater evaporator 1 according to the second exemplary embodiment, with the addition that a portion of the generated steam D is returned to the interior 11. For this purpose, the steam D is discharged from the steam outlet opening 12 via a steam discharge line 12a and made available to a subsequent process, see Figure 9. A steam return line 12b branches off from this steam discharge line 12a, which has a steam pump 12c for conveying the steam D. The steam return line 12b opens through the hydrogen burner 16 into the interior 11, so that the returned steam D in the interior 11 can mix with the steam D generated there and exit together from the steam outlet opening 12.

[0091] Figure 8 shows a schematic cross-section through a saltwater evaporator 1 according to the invention according to an eighth embodiment. The saltwater evaporator 1 according to the eighth embodiment corresponds to the saltwater evaporator 1 according to the first embodiment, with the addition that in this case, an overpressure is generated in the interior 11 to generate superheated steam D. For this purpose, the saltwater A is pumped under pressure into the interior 11 by means of a saltwater pump 11f per first saltwater inlet 11a. The steam outlet 12a has a steam throttle 12d to build up the overpressure and, above a certain pressure, to allow the superheated steam D to flow out. Accordingly, the saltwater outlet 13a also has a saltwater throttle 13b.

[0092] Figure 9 shows a schematic representation of a high-temperature electrolysis plant 2-8 according to the invention with a salt water evaporator 1 according to the invention according to the eighth embodiment.

[0093] The high-temperature electrolysis system 2-8 includes a saltwater source 2, such as a supply of saltwater A directly from the sea, but pre-filtered, or from a tank or similar reservoir. The saltwater A can be pumped from there by a saltwater pump 2a of the saltwater source 2, which is to be distinguished from the saltwater pumps 11e of the saltwater evaporator 1 itself, and fed to the saltwater evaporator 1. Water from an ultrapure water source 3, hydrogen from a hydrogen (H2) storage 7, and oxygen from an oxygen (O2) storage 8 are also supplied to the saltwater evaporator 1 in order to operate as described above. Excess saltwater A can be fed to a saltwater sink 2c after flowing through the saltwater throttle 13b.

[0094] The superheated steam D generated by the salt water evaporator 1 according to the eighth embodiment flows through the steam throttle 12d as described therein and then enters a high-temperature electrolyzer 4, which is powered by electrical energy from a power source 5 through the high-temperature electrolysis. The hydrogen generated by the high-temperature electrolysis is fed to the hydrogen (H2) reservoir 7 and stored there or partially reused to operate the salt water evaporator 1, as previously described. This also applies to the oxygen generated by the high-temperature electrolysis, which is stored in the oxygen (O2) reservoir 8 or partially re-fed to the salt water evaporator 1. Optionally, the salt water A can first be fed to a salt water preheater 2b, which can be operated using excess heat from the high-temperature electrolyzer 4.Alternatively or additionally, the "excess" salt water A can also be used for this purpose. This salt water A is collected by the salt water collector 13 and discharged via its salt water outlet 13a. This salt water A is led from the salt water outlet 13a to the salt water preheater 2b and from there to the salt water sink 2c. In any case, heated salt water A can be fed to the salt water evaporator 1 to accelerate evaporation there or to require less heat there, which can increase the efficiency of the high-temperature electrolysis system 2-8. Optionally, the hydrogen and oxygen produced by the high-temperature electrolyzer 4 can be fed to a compressor 6 to be compressed and stored in compressed form, which can increase the storage capacity of the hydrogen (H2) storage 7 and the oxygen (O2) storage 8.

[0095] LIST OF REFERENCE SYMBOLS (part of the description)

[0096] A salt water

[0097] B Saltwater film

[0098] C H2-O2 (H2O) burner flame

[0099] D (Hot) steam

[0100] Y transverse axis; width

[0101] Z vertical axis; height

[0102] I Salt water evaporator

[0103] 10 Housing; casing

[0104] 10a standing housing part of the housing 10

[0105] 10b Rotating housing part of the housing 10

[0106] 10c Bearings

[0107] II Interior; evaporator chamber

[0108] 11a first, upper saltwater inlets

[0109] 11b second, middle saltwater inlets

[0110] 11c Salt water outlet lld Burner opening

[0111] Ile anteroom llf salt water pumps

[0112] 12 Steam outlet opening

[0113] 12a Steam discharge

[0114] 12b Steam return

[0115] 12c steam pump

[0116] 12d steam throttle

[0117] 13 saltwater collectors

[0118] 13a Saltwater drain

[0119] 13b Saltwater Thrush

[0120] 14 Rotary drive

[0121] 15 Lifting drive

[0122] 16 Heat source; hydrogen burner

[0123] 16a Oxygen (O2) supply of the burner 16

[0124] 16b Hydrogen (H2) supply of burner 16

[0125] 16c Water (H2O) supply of the burner 16 17 Heat source; electric heating element

[0126] 17a Mounting or suspension of the electric heating element 17

[0127] 2 salt water spring

[0128] 2a Saltwater pump of saltwater source 2

[0129] 2b Salt water preheating

[0130] 2c saltwater depression

[0131] 3 ultrapure water source

[0132] 4 High-temperature electrolyzer

[0133] 5 Power source

[0134] 6 compressors

[0135] 7 Hydrogen (H2) storage

[0136] 8 oxygen (O2) storage

Claims

PATENT CLAIMS 1. Salt water evaporator (1) with a housing (10) which essentially encloses an interior space (11) with at least one steam outlet opening (12) and has at least one first salt water supply (11a), wherein the surface of the interior space (11) and the first salt water supply (11a) are designed to allow salt water (A) to run off as a salt water film (B) along the vertical axis (Z) on the surface of the interior space (11), and with at least one heat source (16, 17) which is designed and arranged within the interior space (11) is arranged to heat the side of the salt water film (B) facing away from the surface of the interior space (11), which side faces the heat source (16, 17), in a contactless manner such that exactly a part of the liquid phase of the salt water film (B) is evaporated, wherein the housing (10) further comprises at least one salt water outlet (11c) of the interior space (11), which is arranged along the vertical axis (Z) below the first salt water supply (11a) and is designed to discharge the remaining part of the liquid phase of the salt water film (B) from the interior space (11).

2. Salt water evaporator (1) according to claim 1, wherein the heat source (16, 17) comprises, preferably is, an electric heating element (17), an infrared heating element and / or an inductive heating element.

3. Salt water evaporator (1) according to claim 2, wherein the electrical heating element (17) is arranged along the vertical axis (Z) above the first salt water supply (11a) on the housing (10) by means of a fastening (17a), preferably by means of a suspension (17a), and projects from the fastening (17a) contactlessly along the vertical axis (Z) into the interior (11).

4. Salt water evaporator (1) according to one of the preceding claims, wherein the heat source (16, 17) comprises, preferably is, a hydrogen burner (16), wherein the hydrogen burner (16) preferably burns a hydrogen-water-oxidizer mixture.

5. Salt water evaporator (1) according to claim 4, wherein the hydrogen burner (16) is designed and arranged to generate a burner flame (B), preferably an H2-O2 (H2O) burner flame (B), directed upwards or downwards along the vertical axis (Z).

6. Salt water evaporator (1) according to one of the preceding claims, wherein the interior (11) is conical, at least in the region of the contactless heating by the heat source (16, 17), preferably from the first salt water supply (11a), tapering downwards along the vertical axis (Z) to the salt water outlet (11c).

7. Salt water evaporator (1) according to one of the preceding claims, wherein the housing (10) has a plurality of first salt water inlets (11a), which are preferably arranged along the vertical axis (Z) at the same height and / or perpendicular to the vertical axis (Z) at equal distances.

8. Salt water evaporator (1) according to one of the preceding claims, wherein the housing (10) has a second salt water supply (11b) between the first salt water supply (11a) and the salt water outlet (11c), preferably approximately centrally, which second salt water supply (11b) is also designed to allow salt water (A) to drain off as a salt water film (B) along the vertical axis (Z) on the surface of the interior space (11).

9. Salt water evaporator (1) according to one of the preceding claims, wherein the housing (10) has a plurality of guide channels extending along the vertical axis (Z) towards the interior (11), preferably as far as the salt water outlet (11c) of the interior (11), and preferably decreasing in depth.

10. Salt water evaporator (1) according to one of the preceding claims, wherein the heat source (16, 17) is designed to be positioned, preferably by means of a lifting drive (15), along the vertical axis (Z) relative to the housing (10).

11. Salt water evaporator (1) according to one of the preceding claims, wherein the interior space (11) along the vertical axis (Z) in the area between the first salt water supply (11a) and the salt water outlet (11c) at least in sections, preferably substantially, particularly preferably almost entirely, formed by a rotatable housing part (10b) of the housing (10), wherein the rotatable housing part (10b) of the housing (10) is designed to be driven in rotation relative to the housing (10), preferably by means of a rotation drive (14), about the vertical axis (Z).

12. Salt water evaporator (1) according to one of the preceding claims, wherein the salt water evaporator (1) is designed to return the steam (D) discharged from the interior (11) through the steam outlet opening (12) to the interior (11) partly by means of a steam return (12b), preferably conveyed by means of a steam pump (12c).

13. Salt water evaporator (1) according to one of the preceding claims, wherein the salt water evaporator (1) is designed to operate the interior space (11) under increased pressure, wherein the steam outlet opening (12) is preferably followed by a steam throttle (12d) and / or wherein the first salt water supply (11a) preferably has a salt water pump (11e).

14. Salt water evaporator (1) according to one of the preceding claims, wherein the salt water outlet (11c) is followed by a salt water collector (13), preferably with a salt water throttle (13b), which is designed to collect and discharge the escaping salt water (A).

15. High-temperature electrolysis plant (2-8) with at least one salt water evaporator (1) according to one of the preceding claims.

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