Seawater desalination module with controlled inflow and arrangement of seawater desalination modules

Abstract

Seawater desalination module (0) with an evaporator (1), with a seawater inlet (3) for supplying fresh seawater to the evaporator (1) and with a water outlet (5) for removing unevaporated water from the evaporator (1), wherein a valve (9) connected to a control unit (7) is arranged at the seawater inlet (3) to meter the supply of fresh seawater to the evaporator (1), characterized in that the control unit (7) is designed to actuate the valve (9) depending on the temperature of the water in the evaporator (1), and comprises a pressure cylinder (15) and a spring (17), wherein the spring (17) is connected to the valve (9), wherein the seawater desalination module (0) is designed to float on seawater.

Description

[0001] The invention relates to a seawater desalination module with an evaporator and an arrangement of a plurality of seawater desalination modules.

[0002] It is known in the prior art to desalinate seawater by evaporating it, leaving the salt behind, and then condensing the evaporated water back into a liquid state. Such evaporation can be carried out using units floating on the sea, in particular by using solar energy as the energy source for evaporating the water.

[0003] In this context, JP 2001129538 A relates to an evaporator with an intake section immersed in a liquid source, a conductive medium for guiding the liquid drawn from the intake section, and an evaporation section to which the liquid is supplied from the conductive medium. A solar pump is also provided, consisting of a device and a recovery device that condenses and recovers the liquid evaporated in the evaporator.

[0004] In JP 2001129538 A, in particular, an evaporator open at the top half, a surface open at the bottom half for condensing liquid, the use of a semi-permeable membrane, a bottom water filter and a pumping mechanism driven by evaporation of the water inside.

[0005] DE 10 2005 005 008 A1 relates to a plant for the distillation of liquids with an evaporator and a compressor used for direct vapor compression, wherein the energy for operating the compressor and the other components is provided by the conversion of thermal energy. A jet compressor is used as the vapor compressor.

[0006] Patent CH 712 868 A2 concerns a seawater desalination and decontamination plant powered by solar energy. It consists primarily of a compact input section, an evaporation unit, a vacuum chamber, a compression and condensation unit, a distillate section, and a slag removal section. The evaporation system operates under vacuum. The vacuum allows for a lower evaporation temperature, enabling the use of a cost-effective solar thermal collector. The energy for evaporation is generated by a solar thermal collector and amplified by a heat recovery system. The integrated evaporation and condensation processes allow the vacuum to be maintained continuously with minimal energy consumption, making the entire plant a viable option for meeting drinking and process water needs.The system is designed so that the desired concentration of brine wastewater is produced by regulating the flow rate of the water to be treated.

[0007] DE 1 642 481 A relates to a process and a device for producing freshwater from seawater. In this process, seawater is injected into a hot gas stream under high pressure for evaporation. A vapor-gas mixture is drawn off from an upper part of an evaporation chamber, and the precipitated salts and mineral components, partly liquid, partly solid, or concentrated in water, are drawn off from a lower part of the evaporation chamber. The gas-vapor mixture is then expanded in one or more stages while work is performed, and finally, freshwater is condensed out of the mixture by cooling.

[0008] Alternative designs of floating desalination modules are known in the prior art: For example, CN 111689540 A relates to a floating desalination module that is based on the capillary effect, and CN 113149105 A relates to a floating desalination module in which the day / night temperature difference is used to desalinate the seawater.

[0009] When an evaporator is used, water continuously evaporates inside the desalination module. This increases the salt concentration in the remaining, unevaporated seawater, the residual liquid. For continuous operation of the desalination module, this residual liquid must be continuously replaced with fresh seawater with a correspondingly lower salt content. However, with continuous passive flushing with seawater, the evaporator surface is continuously cooled, and therefore, the temperature required for evaporation cannot build up, or can only build up with difficulty.

[0010] The object of the invention is to solve this problem and to provide a cost-effectively manufactured, floating seawater desalination module.

[0011] The invention is defined by the features of the independent claims. Advantageous further developments and embodiments are the subject of the dependent claims.

[0012] A first aspect of the invention relates to a seawater desalination module with an evaporator, a seawater inlet for supplying fresh seawater to the evaporator, and a water outlet for removing unevaporated water from the evaporator, wherein a valve connected to a control unit is arranged at the seawater inlet to meter the supply of fresh seawater to the evaporator, the control unit being configured to actuate the valve depending on the temperature of the water in the evaporator, and comprising a pressure cylinder and a spring, the spring being connected to the valve, and wherein the seawater desalination module is designed to float on seawater.

[0013] Energy is supplied to the evaporator, which manifests as heat at the evaporator. This heat is transferred to the seawater at or within the evaporator, causing it to at least partially evaporate. Salt remains behind in this process, as it does not evaporate. The evaporated water is largely to completely salt-free. If seawater remains at or within the evaporator, the temperature rises continuously until it reaches its boiling point; further energy input leads to faster evaporation rates. If fresh seawater is added, the enthalpy tends to decrease, and below the boiling point, the temperature also decreases, since fresh seawater is at the temperature of the surrounding sea and therefore significantly below its boiling point.

[0014] The control unit's operation ensures that when a certain temperature is exceeded, preferably above a predefined limit, fresh seawater is added to prevent the salt concentration in the seawater within the evaporator from becoming too high. However, if the temperature drops sufficiently low, the control unit stops the further supply of fresh seawater to maintain effective evaporation and prevent the seawater in or around the evaporator from being lowered to excessively low temperatures by introducing too much fresh seawater.

[0015] In other words, there is a repeated sequence of a first period during which the valve is open and fresh seawater is supplied to the evaporator, as the temperature at the evaporator is sufficiently high, and a second period following the first period during which the valve is closed to prevent the supply of fresh seawater to the evaporator in order to ensure a sufficiently high temperature at the evaporator.

[0016] This advantageously results in a self-optimizing sequence of supplying and stopping the supply of fresh seawater to the evaporator, in order to maintain a sufficiently high temperature for effective evaporation at the evaporator by interrupting the supply of fresh seawater, while simultaneously maintaining a sufficient supply of fresh seawater through recurring, but interrupted, periods in which fresh seawater is supplied to the evaporator, in order to prevent the salt content of the unevaporated water from becoming excessively high with a correspondingly high salt concentration in the evaporator.

[0017] According to an advantageous embodiment, the seawater desalination module further comprises a flow reversal barrier designed to prevent a flow from the water outlet through the seawater inlet into the surrounding seawater.

[0018] According to another advantageous embodiment, the flow reversal barrier comprises a check valve and / or a diaphragm.

[0019] According to a further advantageous embodiment, the control unit is designed to open the valve further to supply fresh seawater when a predetermined temperature of the water located at the evaporator or of an element of the evaporator is exceeded, and to close it further when the predetermined temperature is undershot.

[0020] According to a further advantageous embodiment, the valve is designed to selectively enable or completely prevent the supply of fresh seawater to the evaporator, wherein the control unit is designed to fully open the valve to allow the supply of fresh seawater when the predetermined temperature of the water in the evaporator or of an element of the evaporator is exceeded and to fully close it when the predetermined temperature is undershot.

[0021] According to another advantageous embodiment, the evaporator is solar-powered.

[0022] According to a further advantageous embodiment, the evaporator is arranged in a housing, wherein the seawater inflow is formed through an opening in the housing, and wherein the housing is designed to perform vibrations, excitable by wind and / or waves, and the seawater inflow is arranged such that when the housing is subjected to vibrations, fresh seawater flows into the housing towards the evaporator.

[0023] According to another advantageous embodiment, the control unit is an electronic control unit designed to control an electrically operated pump for conveying fresh seawater into the housing for the evaporator.

[0024] The electrically operated pump is equipped with an electric motor, which is preferably powered by a solar panel. Alternative power sources are possible, such as a battery or energy harvesting from wind and / or the waves of the surrounding seawater.

[0025] According to the invention, the control unit comprises a pressure cylinder and a spring.

[0026] Another aspect of the invention relates to an arrangement of a plurality of seawater desalination modules as described above and below, wherein a first seawater desalination module is connected with its outlet for desalinated water to the seawater inlet of a second seawater desalination module, so that a series connection of several seawater desalination modules is obtained.

[0027] According to a further advantageous embodiment, the arrangement further comprises a monitoring unit designed to monitor the salt content at a predetermined location of the arrangement.

[0028] Preferably, if a predetermined limit regarding salinity is exceeded, no further seawater is pumped through an affected desalination module, as exceeding the predetermined limit may indicate a defect in the desalination module. Furthermore, preferably, each desalination module can be deactivated separately as part of the arrangement, preferably wirelessly, when such a limit is detected.

[0029] Advantages and preferred further developments of the proposed arrangement result from an analogous and substantive transfer of the above statements made in connection with the proposed seawater desalination module.

[0030] Further advantages, features, and details will become apparent from the following description, in which at least one embodiment is described in detail with reference to the drawing. Identical, similar, and / or functionally equivalent parts are identified by the same reference numerals.

[0031] They show: Fig. 1: A cross-section through a seawater desalination module with an evaporator. Fig. 2: A seawater desalination module. Fig. 3: A seawater desalination module according to an embodiment of the invention. Fig. 4: An arrangement of seawater desalination modules according to an embodiment of the invention.

[0032] The representations in the figures are schematic and not to scale.

[0033] Fig. Figure 1 shows a cross-sectional view of the internal structure of a seawater desalination module 0 for producing desalinated water. Inside is a tube S, which has a vapor-permeable membrane M on its upper surface. This allows salt-free water to escape. Energy is collected from sunlight in the form of thermal radiation by the reflector disc R, causing the seawater to evaporate. The water condenses on the condenser K, which is surrounded by cold water, and flows as salt-free water to the bottom of the housing (in the Fig. 1 (This is marked as open water with a water level indicator). An air / water channel L also runs along the housing for leveling.

[0034] Fig. Figure 2 shows an exemplary seawater desalination module 0, which replicates the construction of the evaporator 1 as in the Fig. The evaporator 1 can be used as shown in Figure 1. The evaporator 1 has a seawater inlet 3. This seawater inlet 3 serves to supply fresh seawater to the evaporator 1. For this purpose, a filter F is arranged at the inlet of the seawater inlet 3 to prevent larger particles from being drawn in from the sea. Between the filter F and the evaporator 1, the flow of fresh seawater through the seawater inlet 3 is regulated by a valve 9. The valve 9 is controlled by a control unit 7, which is connected to an actuator 13. The control unit 7 is an electronic control unit and supplies digital signals to the actuator 13, which is an electrical actuator. The actuator 13 is mechanically connected to the valve 9 to selectively stop or allow the flow of fresh seawater to the evaporator 1. The control unit 7 has a digital processing unit that is connected to a temperature sensor on the evaporator 1.If the temperature measured by the temperature sensor exceeds a predefined limit, the processing unit of the control unit 7 detects this and controls the actuator 13 so that the valve 9 is opened to supply fresh seawater to the evaporator 1. The supply of fresh seawater is carried out via an electric pump (not shown). Fig. (2 shown) or by a geometrically configured seawater inflow 3 such that, due to the naturally occurring wave formation during the natural rocking of the seawater desalination module 0 floating on the sea, fresh seawater flows to the evaporator 1 as long as the valve 9 is open. The supply of fresh, cooler seawater to the evaporator 1 has a temperature-reducing effect on the seawater in the evaporator 1. If the temperature in the evaporator 1 falls below the predefined limit, the control unit 7 accordingly activates the actuator 13 to close the valve 9, so that no further fresh seawater flows to the evaporator 1 and the temperature there can rise again.To avoid high-frequency changes between valve opening positions, hysteresis can be implemented in the control unit 7. This ensures that after exceeding the first limit value due to a temperature rise and the resulting opening of valve 9, the temperature must fall below a second limit value (which is lower than the first) before the valve 9 closes again. Furthermore, when the temperature falls below the second limit value, and the valve 9 opens as a result, the temperature must only rise above the first limit value when the temperature subsequently rises again before the valve 9 opens again. The remaining seawater with a high salt concentration leaves the evaporator 1 via a water drain 5, while the condensate can be discharged via an outlet 19 (see figure). Fig. 4) Either in the seawater inlet 3 or in the water outlet 5 a flow reversal barrier 11, designed as a backflow barrier, is provided to ensure that the functionality implemented in the control unit 7 can be carried out correctly by preventing a backflow.

[0035] Fig. Figure 3 shows a similar structure to that of the Fig. 2, however, a different control unit 7 is implemented here. In the present case of the Fig. In section 3, the control unit 7 is implemented by a pressure cylinder 15 and a spring 17. A thermo-mechanical coupling exists between the pressure cylinder 15 and the temperature in the evaporator 1. As the temperature rises, the pressure in the pressure cylinder 15 increases and pushes against the resistance of the spring 17, which in turn is connected to the valve 9. Thus, as the temperature in the evaporator 1 rises, a mechanical coupling is established to open the valve 9, while as the temperature at the evaporator 1 falls, the valve 9 is actuated to close, since the expanded pressure cylinder 15 cools down. A mechanical overcoming point can be provided in one or both directions of the possible movement of the pressure cylinder 15, for example, a toggle lever, which requires overcoming a certain limiting force to close or open the valve 9.This creates a natural hysteresis and avoids intermediate states in valve 9; instead, valve 9 is either fully closed or fully open. This is ensured by the snap mechanism, if one is optionally provided. Alternatively, a continuously acting mechanical coupling between the temperature at the evaporator 1 and the continuously adjustable valve position of valve 9 is used. The remaining components of the... Fig. 3 can be configured analogously from the Fig. 2. The description of the Fig. 2 is applicable accordingly.

[0036] Fig. Figure 4 shows an arrangement of multiple seawater desalination modules 0 that together feed a main line for desalinated water. At least two of the seawater desalination modules 0 can be connected in series, so that the desalinated water from a first seawater desalination module 0 is fed through the outlet 19 to the seawater inlet 3 of a second seawater desalination module 0. Individual module groups and chains of seawater desalination modules 0 can be switched on or off individually or as a branch, depending on whether a valve within a branch or at the end of a branch to the common freshwater main line is closed. If a monitoring unit is also provided that monitors for a direct fault or indirectly infers one by measuring the salinity of the desalinated seawater at a respective seawater desalination module 0, these valves can be controlled accordingly.These valves are not necessarily the same as the valves 9 from the . Fig. 2 and Fig. 3, however, valves 9 can also be used from the Fig. 2 and Fig. 3. This allows defective seawater desalination modules to be isolated from a central manifold, particularly via wireless remote control.

[0037] Although the invention has been further illustrated and explained in detail by means of preferred embodiments, the invention is not limited by the disclosed examples and other variations can be derived from them by the person skilled in the art. Reference symbol list 0 Seawater desalination module 1 evaporator 3 Seawater inflow 5 Water drain 7 Control unit 9 valve 11 Flow reversal barrier 13 Actuator 15 pressure cylinders 17 spring 19 Outlet for desalinated water F Filter K capacitor L Air / water channel for leveling M Vapor-permeable membrane on hose S R Reflector disc S hose

Claims

[1] Seawater desalination module (0) with an evaporator (1), with a seawater inlet (3) for supplying fresh seawater to the evaporator (1) and with a water outlet (5) for removing unevaporated water from the evaporator (1), wherein a valve (9) connected to a control unit (7) is arranged at the seawater inlet (3) to meter the supply of fresh seawater to the evaporator (1), characterized by , that the control unit (7) is designed to control the valve (9) depending on the temperature state of the water in the evaporator (1), and comprises a pressure cylinder (15) and a spring (17), wherein the spring (17) is connected to the valve (9), wherein the seawater desalination module (0) is designed to float on seawater. [2] Seawater desalination module (0) according to claim 1, further comprising a flow reversal barrier (11) designed to prevent a flow from the water outlet (5) through the seawater inlet (3) into the surrounding seawater. [3] Seawater desalination module (0) according to claim 2, wherein the flow reversal barrier (11) comprises a check valve and / or a membrane. [4] Seawater desalination module (0) according to one of the preceding claims, wherein the control unit (7) is configured to further open the valve (9) to supply fresh seawater when a predetermined temperature of the water in the evaporator (1) or of an element of the evaporator (1) is exceeded and to further close it when the predetermined temperature is undershot. [5] Seawater desalination module (0) according to claim 4, wherein the valve (9) is configured to selectively allow or completely prevent the supply of fresh seawater to the evaporator (1), and wherein the control unit (7) is configured to fully open the valve (9) to allow the supply of fresh seawater when the predetermined temperature of the water in the evaporator (1) or of the element of the evaporator (1) is exceeded and to fully close it when the predetermined temperature is undershot. [6] Seawater desalination module (0) according to one of the preceding claims, wherein the evaporator (1) is arranged in a housing, wherein the seawater inlet (3) is formed through an opening in the housing and wherein the housing is designed to perform vibrations, excitable by wind and / or waves and the seawater inlet (3) is arranged such that when the housing is performed, fresh seawater flows into the housing to the evaporator (1). [7] Arrangement of a plurality of seawater desalination modules (0) according to one of the preceding claims, wherein a first seawater desalination module (0) is connected with its outlet (19) for desalinated water to the seawater inlet (3) of a second seawater desalination module (0), such that a series connection of several seawater desalination modules (0) is obtained. [8] Arrangement according to claim 7, further comprising a monitoring unit designed to monitor the salt content at a predetermined location of the arrangement.

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