NL2026420B1

NL2026420B1 - Desalination unit, desalination plant, method for desalination of saline water in order to obtain freshwater, and desalinated water

Info

Publication number: NL2026420B1
Application number: NL2026420A
Authority: NL
Inventors: Petrus Franciscus Krijbolder Wouter
Original assignee: Petrus Franciscus Krijbolder Wouter
Priority date: 2020-09-07
Filing date: 2020-09-07
Publication date: 2022-05-04

Abstract

Desalination unit for desalination of saline water, i.e. saltwater such as seawater, comprising an evaporation chamber configured to receive the saline water through an inlet, and configured to at least partially evaporate the saline water in order to obtain water vapor in the evaporation chamber, and a condensation chamber configured to receive desalinated water, wherein the evaporation chamber and the condensation chamber are separated by a water permeable separation panel configured to collect the water vapor, and having a receiving surface and an expelling surface, wherein the receiving surface faces the evaporation chamber and is configured to receive the water vapor from the evaporation chamber, and wherein the expelling surface faces the condensation chamber and is configured to expel the water vapor into the condensation chamber as desalinated water (i.e. freshwater).

Description

DESALINATION UNIT, DESALINATION PLANT, METHOD FOR DESALINATION OF SALINE WATER IN ORDER TO OBTAIN FRESHWATER, AND DESALINATED

WATER The present invention relates to a desalination unit for desalination of saline water, such as seawater, brackish water, waste water and/or polluted water. The present invention further relates to a desalination plant, comprising a plurality of desalination units, and a method for (preferably large scale) desalination of saline water, such as seawater and brackish water (waste water and/or polluted water may be purified as well). Further, the present invention relates to desalinated water obtained from the desalination unit, the desalination plant, and/or the method for desalination of saline water, preferably for human use and/or for irrigation. In general, desalination of water entails removing salt and/or minerals therefrom. Fresh water, which may be suitable for drinking and cooking purposes, as well as irrigation water to grow agricultural crops, maintain landscapes, and revegetate disturbed soils in dry areas and during periods of less than average rainfall, or the like, is obtainable by desalinating a saline or brackish water source, as well as, for instance, waste water and polluted water. Hereinafter the term saline water will be used, which may also encompass brackish water, waste water, and polluted water for the sake of convenience. The Earth’s oceans are prime examples of such saline water sources, i.e.

saltwater sources. Parts of the world rely partly or fully on fresh (drinking, i.e. potable) water obtained from desalination due to the lack of natural fresh water sources. Lack of natural fresh water sources may be caused by, for instance, pollution of water sources, drought, geographical features, or the like. According to the United Nations Environment Programme (UNEP), small countries such as the Maldives, Malta and the Bahamas and bigger ones like Saudi Arabia, and the UAE rely fully on desalination of saline water, in particular sea water, to meet their fresh water needs. Given the changes in our global climate, Australia, Spain, China, and the USA (California) are amongst the upcoming markets for desalination plants. The United Nations (UN) estimates that currently about 1% of the world’s population requires desalinated water as their fresh water supply. Furthermore, the UN estimates that 14% of the world’s population may encounter water scarcity by 2025, a figure that is to rise alarmingly by the year 2050. One of UN's sustainable development goals is the availability of safely managed drinking water for the majority of the world’s population by 2030. Currently, desalination is largely limited to more affluent countries, especially those with ample fossil fuels and access to seawater. Hence, the need for desalination systems is projected to grow significantly in the coming years.

Various techniques are utilized to desalinate water, such as distillation, ion exchange, membrane processes, freezing desalination, geothermal desalination, solar desalination, and the like. An example of a widely utilized membrane process is reverse osmosis (RO), a method that has become world leader in desalination processes. Drawbacks are — amongst others — expensive, and energy intensive machinery, high maintenance and/or production costs, as well as environmental issues. Other desalination processes, such as multi-stage flash distillation (MSF) and vapor-compressing (VC) also need large amounts of energy to obtain fresh water. Although the World Bank recommended “Dew Vaporation” in 2019 as a cheaper desalination method, practical implementations thereof have been limited. Existing techniques have a variety of drawbacks as mentioned above. For instance, they may require a large amount of energy during fresh water production and/or may require significant maintenance and/or production costs. Accordingly, in order to meet the growing global fresh water demand, in particular for low income countries, there is a need for a cheaper desalination system and method with low maintenance, production, and running costs, which is also regularly urged by the UN. The present invention aims to mitigate drawbacks of the prior art by — according to a first aspect of the invention — providing a desalination unit for desalination of saline water, such as seawater, comprising an evaporation chamber configured to receive the saline water through an inlet, and configured to at least partially evaporate the saline water in order to obtain water vapor (i.e. steam) in the evaporation chamber, and a condensation chamber configured to receive desalinated water, wherein the evaporation chamber and the condensation chamber are separated by a water permeable separation panel configured to collect the water vapor, and having a receiving surface and an expelling surface, wherein the receiving surface faces the evaporation chamber and is configured to receive the water vapor from the evaporation chamber, and wherein the expelling surface faces the condensation chamber and is configured to expel the water vapor into the condensation chamber as desalinated water.

Accordingly, a desalination unit with low-cost construction is obtained, wherein the water is evaporated in the evaporation chamber, by any means known to the skilled person, and is efficiently transported to a condensation chamber without the need for moving parts. The water vapor {now without salts and/or minerals) may condense at the receiving surface, within the water permeable separation panel, and/or at the expelling surface, depending on constraints, such as power consumption constraints. For instance, the separation panel may or may not be actively or passively cooled depending on power consumption constraints and/or cost constraints. By using natural condensation of the water vapor on the receiving surface of the separation panel, no separate condenser system is required.

According to an example of the desalination unit, the separation panel is provided with capillary tubes extending from the receiving surface to the expelling surface, such that the water vapor is allowed to enter the capillary tubes at the receiving surface, and is expelled as desalinated water at the expelling surface. Preferably, the separation panel is provided with about 10 — 1000 capillary tubes per cm?, more preferably about 100 — 500 capillary tubes per cm? Naturally, it is also possible to provide the separation panel with more than 1000 capillary tubes per cm?. Capillary tubes are tubes with relatively small diameter which provide capillary action (or “wicking’) to liquids, such as water (vapor), coming in contact therewith. This allows the liquid to be transported from a lower part of the tube to a higher part of the tube without energy input, and against the force of gravity. Generally speaking, the smaller the diameter of the capillary tube, the higher the liquid may be transported therewith. Accordingly, preferably the thickness of the separation panel and the diameter of the capillary tubes are balanced such that a liquid, in particular water, contacting a capillary tube at the receiving surface may be transported through the separation panel to the expelling surface, i.e. along a length at least substantially equal to the thickness of the separation panel. As capillary tubes do not require any energy input to transport the water vapor through the separation panel, energy efficient fresh water transportation from the evaporation chamber (upwards) to the condensation chamber is provided.

Preferably, a thickness of the separation panel is substantially equal to a length of the capillary tubes. Preferably, the thickness of the separation panel is about 0.5 cm — 20 cm, and more preferably about 1 — 10 cm. Preferably, the diameter of each of the capillary tubes is about 0.1 mm — 1 cm, more preferably about 0.1 mm — 5 mm, and more preferably about 0.1 — 2.5 mm. Preferably, the separation panel is manufactured from a material comprising at least one of a plastic, metal {such as stainless steel, aluminum, or other preferably corrosion resistant metals), fibre-reinforced plastic, ceramic material, or a combination thereof. The capillary tubes are preferably formed integrally with the separation panel, e.g. formed in the separation panel as through holes. When the capillary tubes are formed in the separation panel with an angle with respect to the normal vector of the separation panel, the capillary tubes may be longer in length than the thickness of the separation panel. Preferably, the separation panel is substantially rigid. Additionally or alternatively, the capillary tubes may protrude from the separation panel, preferably the capillary tubes protrude from the expelling surface of the separation panel.

According to an example of the desalination unit, the desalination unit is oriented such that the saline water in the evaporation chamber does not directly contact the separation panel. For instance, the separation panel is preferably situated well above the saline water entering the unit, such that direct contact of the saline water with the separation panel does not occur. The desalination unit is preferably oriented at an angle, and as a result thereof the separation panel, evaporation chamber, and condensation chamber are oriented at an angle as well. Thus, under the force of gravity, the relatively lightweight water vapor in the evaporation chamber rises towards the separation panel, and the relatively heavyweight saline water and/or brine — still located in the evaporation chamber — remains in the evaporation chamber. Subsequently, freshly obtained desalinated water (i.e. freshwater) — received in the condensation chamber — flows downwards in the condensation chamber towards the bottom end (e.g. lower end) of the desalination unit. Preferably, the evaporation chamber is located beneath the condensation chamber. According to an example of the desalination unit, the separation panel is tilted with respect to a {5 gravitational acceleration vector such that an outer-pointing normal vector of the expelling surface has a component opposite to the gravitational acceleration vector. Preferably, a wall of the evaporation chamber opposite to the separation panel is a bottom wall of the desalination unit, wherein the saline water flows along the bottom wall of the desalination unit. In other words, the separation panel, which divides the evaporation chamber and the condensation chamber, is tilted away from a vertical orientation, such that saline water flowing into the evaporation chamber does not directly contact the separation panel. For instance, the desalination unit may have a substantially cuboid shape, wherein the separation panel is substantially parallel to surface of the desalination unit running in longitudinal direction thereof, and wherein the lower side of the separation panel (being the receiving surface) faces the evaporation chamber, and the upper side of the separation panel (being the expelling surface) faces the condensation chamber. Naturally, the desalination unit may have any suitable shape, which may also be configured to be tilted with respect to a gravitational acceleration vector, such that the outer-pointing normal vector of the expelling surface has the component opposite to the gravitational acceleration vector, i.e. the expelling surface being the upper side of the separation panel.

According to an example of the desalination unit, a saline water inflow rate through the inlet is balanced with a saline water evaporation rate such that the saline water in the evaporation chamber does not directly contact the separation panel and/or such that the evaporation process does not come to a standstill. By balancing the saline water inflow rate and the evaporation rate, the saline water level in the evaporation chamber does not rise to such an extent that the separation panel is directly contacted by the saline water and/or the saline water in the evaporation chamber becomes brine, yet not overly salty, and preferably enough water remains to prevent crystallization of salts. Accordingly, clogging in the desalination unit and pollution of the environment surrounding the desalination unit is effectively mitigated.

5 According to an example of the desalination unit, the separation panel is formed so as to form a gully at the expelling surface side thereof, so as to collect the desalinated water in the gully. For instance, the separation panel may be (partially) U-shaped or V-shaped such that a gully is formed. Preferably, the separation panel comprises a first inclined panel and a second inclined panel which are connected with each other, the first inclined panel and the second inclined panel being inclined such that a gully (or gutter) is formed at a connection between the first inclined panel and the second inclined panel. In other words, the first inclined panel is inclined with respect to the second inclined panel. Preferably, the connection between the first inclined panel and the second inclined panel is formed by a gutter element, preferably a U-shaped gutter element. Preferably, the connection between the first inclined panel and the second inclined panel, such as the gutter element, is not water permeable. Accordingly, the connection, such as the gutter element, is not provided with capillary tubes. Preferably, the connection, such as the gutter element, is inclined with respect to a gravitational acceleration vector such that the fresh water in the condensation chamber is transported along the connection by means of gravity. By orienting the connection, such as the gutter element, in such manner, i.e. inclined, no energy and/or moving parts is required to transport the fresh water to an outlet and/or reservoir located at a lower end of the desalination unit, in particular a lower end of the condensation chamber. Accordingly, no moving parts and/or energy are required to transport the water vapor to the condensation chamber as fresh water and subsequently transporting the fresh water to a reservoir and/or an outlet of the condensation chamber. Preferably, the separation panel is provided with grooves and/or corrugations in the expelling surface thereof, which grooves and/or corrugations are preferably provided running from the capillary tubes to the gully, in order to guide the fresh water, i.e. desalinated water, from the capillary tubes to the gully.

According to an example of the desalination unit, the evaporation chamber further comprises a heating element configured to heat the saline water in order to obtain the water vapor. The heating element may be provided in the evaporation chamber in such manner that the saline water is heated by means of conduction. For instance, the heating element may be provided in a wall of the evaporation chamber which contacts the saline water during use. The heating element may be any suitable heating element known to the skilled person, such as — but not limited to — a resistance wire heater, a thick film heater, a composite heating element, geothermal heating, or the like. Preferably, the power supply for the heating element is provided by solar panels, wind turbines,

and/or heat exchangers configured to extract power from the saline water, such as the seawater, or another (natural) heat source.

According to an example of the desalination unit, the heating element is provided at least at a wall of the evaporation chamber opposite to the separation panel. Preferably, the saline water flows along said wall, and preferably the desalination unit is oriented such that the saline water does not contact the separation panel during use. Preferably, said wall is a lower wall of the evaporation chamber, such that the saline water is heated from below.

According to an example of the desalination unit, the heating element comprises vanes, or any other contact surface increasing means, so as to increase a contact surface between the heating element and the saline water. Preferably, the vanes are disposed on the interior surface of a wall of the evaporation chamber, and preferably said wall is a wall of the evaporation chamber opposite to the separation panel. Preferably, the vanes are disposed so as to be oriented perpendicular to said wall Preferably, a longitudinal axis of a vane is substantially parallel to a longitudinal axis of the evaporation chamber. Alternatively, the longitudinal axis of the vane is angled with respect to a longitudinal axis of the evaporation chamber, such that the flow velocity of the saline water along the wall of the evaporation chamber is lowered.

According to an example of the desalination unit, the inlet comprises a pre-heating element configured to pre-heat the saline water before reaching the evaporation chamber. Preferably, the pre-heating element is a heating tube having a heating tube inlet and a heating tube outlet, wherein the heating tube inlet is configured to allow saline water to enter the heating tube, and wherein the heating tube outlet is connected to the inlet of the evaporation chamber. Accordingly, the saline water entering the evaporation chamber is pre-heated such that the evaporation rate of the saline water in the evaporation chamber is increased. By efficiently pre-heating the saline water, less energy is required in the evaporation chamber to evaporate the water. Preferably, the saline water is pre-heated in the pre-heating element to such extent that evaporation thereof starts to take place upon entering the evaporation chamber through the inlet. Preferably, the inlet further comprises pre-treatment means configured to filter and/or disinfect the saline water before reaching the evaporation chamber, for instance, in order to prevent debris, plastics, bacteria, other pollutants or the like from entering the desalination unit. Preferably, said pre-treatment means comprise at least one of a filter, such as a sieve, and an Ultraviolet (UV) light transmitter. The filter may for instance remove solid particles from the saline water. The UV light transmitter may for instance purify/disinfect the saline water by destroying bacteria, microorganisms and the like.

According to an example of the desalination unit, the inlet and the brine outlet are each provided with a valve located, respectively, at each end of the desalination unit, thus forming a sealed unit with a water film running between said valves. Balancing the saline water inflow rate, saline water evaporation rate, and brine outflow rate with these valves allows for regulation of the pressure inside the evaporation chamber. Maintaining a lower atmospheric pressure within the units allows for a lower boiling point of the saline water, and thereby reducing the energy consumption required to evaporate the saline water as compared to water evaporation at 1.013 bar (sea level) . According to an example of the desalination unit, it further comprises a desalinated water outlet connected to the condensation chamber, and configured to allow the desalinated water to flow out of the condensation chamber. The outlet may be any type of outlet known to the skilled person, which is suitable to allow the fresh water, i.e. desalinated water, to exit the condensation chamber. The outlet may be connected to a desalinated water tank or a further water transport means.

According to an example of the desalination unit, it further comprises a brine outlet connected to the evaporation chamber, and configured to allow brine formed by partial evaporation of the saline water to flow out of the evaporation chamber. Namely. evaporating saline water results in a waste product with very high salt content, i.e. brine. The brine is preferably regularly or continuously disposed of. The brine outlet is configured to allow the brine to exit the evaporation chamber, and may for instance be connected to a brine reservoir or a further brine transport means. The brine may for instance be dispersed in a saline water body, such as an ocean, or may be transported for further use, such as salt extraction or the like.

According to an example of the desalination unit, a saline water inflow rate through the inlet is balanced with a brine outflow rate through the brine outlet. By balancing the saline water inflow rate and the brine outflow rate the saline water level in the evaporation chamber does not increase to such extent that the saline water (and/or brine) comes near the separation panel. Preferably, the brine outflow rate is higher than the saline water inflow rate so as to establish a lower pressure in the evaporation chamber, preferably lower than an atmospheric pressure, e.g. at sea level. Under lower pressure, water evaporates (e.g. boils) at a lower temperature (i.e. lower pressure reduces the boiling point of the water), such that power consumption by for instance a heating element may be lowered.

According to an example of the desalination unit, the saline water inflow rate, the saline water evaporation rate, and the brine outflow rate are balanced. Balancing the saline water inflow rate, saline water evaporation rate, and brine outflow rate allows for a predictable desalinated water (i.e.

fresh water) output without the risk of the saline water and/or brine coming close to the separation panel. Thus said balancing may regulate the atmospheric pressure inside the evaporation chamber. Accordingly, a lower than atmospheric pressure may be maintained in the evaporation chamber so as to lower the boiling point of the (saline) water, and thereby reducing the power consumption required to evaporate the saline water.

According to an example of the desalination unit, it further comprises a desalinated water storage container connected with the condensation chamber and configured to store the desalinated water from the condensation chamber. The desalinated water, i.e. fresh water, may at a later time or continuously be transported from the container to the user of the desalinated water. For instance, water in the container may periodically be pumped into a transport vessel, or may be continuously pumped from the container through a transportation pipe. According to an example of the desalination unit, it further comprises an elongate housing, wherein the evaporation chamber and the condensation chamber extend in longitudinal direction of the housing, along substantially the full length of the elongate housing. An elongate housing allows for a long travel path of the saline water through the evaporation chamber such that the saline water has ample time to warm up and evaporate. The length, width and/or height of the elongate housing may be adjusted, for instance to allow for larger saline water input and — as a result thereof — higher desalinated water output. According to an example of the desalination unit, it further comprises pressure regulation means configured to adjust an atmospheric pressure in the evaporation chamber. By controlling the (air) pressure in the evaporation chamber, the boiling point of the saline water may be chosen. For instance, a lower than atmospheric pressure in the evaporation chamber leads to evaporation of the saline water at lower temperatures, which may lower power consumption required for heating the saline water. According to an example of the desalination unit, the pressure regulation means comprise at least a controllable inlet valve comprised in the inlet of the desalination unit. The controllable inlet valves are preferably slide valves. Other valve types known to the skilled person may naturally be utilized. The controllable inlet valve allows for controlling the saline water inflow rate into the evaporation chamber.

According to an example of the desalination unit, the pressure regulation means comprise at least a controllable outlet valve comprised in the brine outlet of the desalination unit. The controllable outlet valve is preferably a slide valve. Other valve types known to the skilled person may naturally be utilized. The controllable outlet valve allows for controlling the brine outflow rate out of the evaporation chamber.

Preferably, the pressure regulation means comprise the controllable inlet vale and the controllable outlet valve, wherein the saline water inflow rate into the evaporation chamber, and the brine outflow rate out of the evaporation chamber are balanced. Preferably, the saline water inflow rate and the brine outflow rate are balanced such that a relatively low atmospheric pressure is maintained in the evaporation chamber. Preferably, the atmospheric pressure is such that it lowers the boiling point of the water in the evaporation chamber, as compared to the boiling point under standard atmospheric conditions at sea-level, i.e. standard sea-level conditions (SSL). According to an example of the desalination unit, the pressure regulation means comprise a vacuum pump configured to lower the air pressure in the evaporation chamber. By lowering the (air) pressure in the evaporation chamber, the boiling point of the saline water may be chosen. For instance, lowering the (air) pressure in the evaporation chamber lowers the boiling point of the saline water such that less energy is required to evaporate the saline water. According to an example of the desalination unit, the inlet further comprises a pump configured to pump the saline water into the evaporation chamber. The pump, or a further pump, may be connected to the pre-heating element in order to urge the saline water through the pre-heating element and towards the inlet of the evaporation chamber. In accordance with a second aspect of the invention, desalinated water (i.e. freshwater) is provided which is obtained through desalination by means of a desalination unit according to the above. The desalination unit may be provided with any of the above examples thereof, and combinations of said examples. For instance, the desalinated water may be provided with salts and/or minerals which make the saline water drinkable for persons and/or animals, and/or suitable for irrigation; likewise, brackish water, polluted water and waste water can be treated. The desalinated water may also be disinfected (i.e. sterilized), e.g. by means of physical or chemical disinfection. Chemical disinfection may include the use of a disinfectant, which disinfectant may comprise at least one of chlorine, ozone, halogens (such as bromine and iodine), bromine chloride, metals (such as copper and silver), and other chemical disinfectant known to the skilled person. Physical disinfection may include the use of at least one of ultraviolet light, electronic radiation, gamma rays, soundwaves, and heat. Disinfection of (desalinated) water removes, deactivates, or kills organisms such as bacteria, viruses, fungi, yeasts, parasites, and/or other microorganisms. The (desalinated) water may also be filtered in order to remove particles from therefrom, e.g. by means of a carbon filter. Preferably, the desalination unit comprises disinfection means configured to disinfect the desalinated water by means of chemical and/or physical disinfection. Water which has been disinfected and desalinated may also be referred to as potable water or drinking water.

In accordance with a third aspect of the invention a desalination plant is provided, said desalination plant comprising a plurality of desalination units according to the above. Each of the plurality of desalination units may be provided with any of the above examples thereof, and/or combinations of said examples.

According to an example of the desalination plant, the plarality of desalination units is at least partially submerged in a saline water body. Preferably, the saline water body is a sea, ocean or lake. The submersion depth of the plurality of desalination units may be chosen such that the water pressure at said depth is sufficient to urge the saline water to enter an evaporation chamber of a desalination unit through the inlet and/or pre-heating element thereof.

According to an example of the desalination plant, it further comprises a shared desalinated water storage container connected with a plurality of condensation chambers from the plurality of desalination units, and configured to store desalinated water from the plurality of condensation chambers. The desalination water produced by the plurality of desalination units may thus be centrally collected in the shared desalinated water storage container. The desalinated water in the storage container may periodically be transported by or to a vessel, such as a floating production storage and offloading unit (FPSO).

According to an example of the desalination plant, it further comprises a raised platform extending above the plurality of desalination units, and configured to be accessible to persons. Preferably, the raised platform is at least partially raised above the saline water body, such as above the surface of a sea or lake. IL is preferred that the raised platform is at least partially raised above a nominal wave height of the saline water body. Preferably, the raised platform is at least partially raised above a nominal maximum tidal height of the saline water body. The platform may comprise a variety of facilities, such as — but not limited to — personnel quarters, pumps, energy plant{s), such as solar panels, gas turbines, wind turbines or the like, elevators, helicopter platforms, water vessel docking facilities, or the like.

According to an example of the desalination plant, the plurality of desalination units are disposed so as to form channels therebetween, said channels being configured to receive part of the saline il water so as to cool the condensation chamber by means of the saline water. For instance, a row of desalination units may be provided, wherein a first channel is formed on the side of the row where the condensation chambers of the desalination units are located, such that the condensation chambers face the first channel. Further, for instance, on the opposite side of said first channel, another row of desalination units may be provided, wherein the condensation chambers of said another row of desalination units face said first channel. Further, for instance, the evaporation chambers of said another row of desalination units may face evaporation chambers of a still further row of desalination units. Preferably, a second channel is formed adjacent said still further row of desalination units, wherein the condensation chambers of said still further row of desalination units face said second channel. In this configuration, even further rows of desalination units may be provided, wherein the rows of desalination units face a further channel. Accordingly, the condensation of desalinated water in the condensation chamber is improved, without additional power consumption as natural cooling resources, such as seawater, are utilized for cooling. Other parts or machinery of the desalination plant, such as pumps or the like, may also be cooled by means of saline water (channels).

According to a fourth aspect of the invention, desalinated water (i.e. freshwater) is provided, which is obtained through desalination by means of a desalination plant according to the above. The desalination plant may be provided with any of the above examples thereof, and combinations of said examples. For instance, the desalinated water may be provided with salts and/or minerals which make the saline water drinkable for persons and/or animals, and/or suitable for irrigation. The desalinated water may also be disinfected (i.e. sterilized), e.g. by means of physical or chemical disinfection. Chemical disinfection may include the use of a disinfectant, which disinfectant may comprise at least one of chlorine, ozone, halogens (such as bromine and iodine), bromine chloride, metals (such as copper and silver), and other chemical disinfectant known to the skilled person. Physical disinfection may include the use of at least one of ultraviolet light, electronic radiation, gamma rays, soundwaves, and heat, Disinfection of (desalinated) water removes, deactivates, or kills organisms such as bacteria, viruses, fungi, yeasts, parasites, and/or other microorganisms. The (desalinated) water may also be filtered in order to remove particles from therefrom, e.g. by means of a carbon filter. Preferably, the desalination plant comprises disinfection means configured to disinfect the desalinated water by means of chemical and/or physical disinfection. Water which has been disinfected and desalinated may also be referred to as potable water or drinking water.

According to a fifth aspect of the invention, a method for desalination of saline water in order to obtain freshwater is provided, said method comprising the steps of:

- providing a desalination unit and/or a desalination plant according to the above, - receiving saline water in the evaporation chamber of the desalination unit, - heating the saline water in order to obtain water vapor in the evaporation chamber, - receiving the water vapor in the condensation chamber as desalinated water, by leading the water vapor through the separation panel of the desalination unit, and - collecting the desalinated water in the condensation chamber as freshwater.

It is to be appreciated that the provided desalination unit and/or desalination plant may be provided with any of the above examples thereof, and/or combinations of said examples.

By scaling up the number of desalination units, in for instance the desalination plant, the present invention provides a scalable desalination method which can achieve desalination of industrial magnitude.

According to a sixth aspect of the invention, desalinated water (i.e. freshwater) is provided which is obtained by the above method.

For instance, the desalinated water may be provided with salts and/or minerals which make the saline water drinkable for persons and/or animals, and/or suitable for irrigation.

The desalinated water may also be disinfected (i.e. sterilized), e.g. by means of physical or chemical disinfection.

Chemical disinfection may include the use of a disinfectant, which disinfectant may comprise at least one of chlorine, ozone, halogens (such as bromine and iodine), bromine chloride, metals (such as copper and silver), and other chemical disinfectant known to the skilled person.

Physical disinfection may include the use of at least one of ultraviolet light, electronic radiation, gamma rays, soundwaves, and heat.

Disinfection of (desalinated) water removes, deactivates, or kills organisms such as bacteria, viruses, fungi, yeasts, parasites, and/or other microorganisms.

The (desalinated) water may also be filtered in order to remove particles from therefrom, e.g. by means of a carbon filter.

Water which has been disinfected and desalinated may also be referred to as potable water or drinking water.

The present invention will hereafter be elucidated with reference to the attached drawings, wherein: - Figure 1 shows a schematic overview of an example of a desalination plant; - Figure 2 shows a longitudinal cross-sectional schematic overview of a desalination unit; and - Figure 3 shows a transverse cross-sectional schematic overview of a desalination unit.

In Figure 1 a schematic overview of a desalination plant 100 is shown.

The plant 100 is partially submerged in seawater SW, such that part of the plant 100 lies below sea level SL and part of the plant 100 lies above sea level SL. The desalination plant 100 comprises a raised platform 101 which is raised above sea level SL, and preferably such that the highest expected waves do not reach the majority of the platform 101. The platform 101 comprises any number of required utilities, such as personnel quarters, communication means, desalination plant control means, power generation means, and the like. Some of such utilities may for instance be housed in a platform building 102. For transport of for instance personnel and equipment, a helipad 104 may be provided, which may provide a landing area for one or more helicopters 1040, as shown. The plant 100 may be anchored to the seabed or any other suitable anchoring point by means of anchoring cables 105, or other suitable anchoring means. The anchoring cables 105 may be attached to the platform 101 and or the submerged part of the plant 100. The desalination plant 100 may be provided with (electrical) power by means of a power cable 108, and/or it may be provided with power by means of power generation means, such as solar panels, wind turbines, gas turbines, combustion engines, nuclear power, wave energy converters and the like. Further, the platform 101 may comprise moving means, such as an elevator 103, to move personnel and/or equipment to and from the submerged part of the desalination plant 100. The moving means may for instance utilize dedicated actuators or the like to lower and raise the moving means, or may utilize a crane 112 or the like. The crane 112 may alternatively or additionally be used for loading and offloading equipment and/or personnel from the platform 101 onto a ship or the like.

Still referring to Figure 1, the desalination plant 100 comprises a plurality of desalination units 1, which will be described in detail below. The desalination units 1 are submerged in the seawater SW, below sea level SL. Accordingly, the present water pressure allows the seawater SW to enter the desalination units 1 naturally, e.g. without pumps, as the interior of the desalination units 1 is preferably kept at a lower atmospheric pressure than the exterior seawater pressure. A desalination unit | receives saline water, in this case seawater SW, which it subsequently desalinates to obtain desalinated water, which may also be referred to as fresh water. The obtained fresh water may be stored in a fresh water tank 111. The stored fresh water may be pumped from the fresh water tank 111 to for instance a vessel 106, such as a tanker ship 106 with a liquid reservoir 1060, for transport to the user of the fresh water. Alternatively or additionally, the fresh water may be pumped from the fresh water tank 111 to another location by means of a fresh water pipe 109. As the fresh water is obtained from the seawater SW by means of distillation, a waste product called brine is obtained. Brine is water with a very high concentration of salts and other constituents such as minerals, organic matter, and the like. The brine is collected in a brine tank 110 and may for instance be disposed of by pumping the brine to a vessel 106, such as a tanker ship 106, or to another location by means of a brine pipe 107. The brine pipe 107 and fresh water pipe 109 may lie in and/or on the seabed SB.

Figure 2 shows a longitudinal cross-section of a desalination unit 1 which is configured to desalinate salt water (i.e. saline water), such as seawater SW, in order to obtain desalinated water, also called fresh water.

The unit 1 is contained by a (preferably airtight) housing 10, and comprises an evaporation chamber 2, which is configured to heat up and evaporate salt water, which salt water is obtained through its inlet 6. The inlet 6 may comprise a controllable slide valve 60, which is configured to control the inflow of salt water into the evaporation chamber 2. The unit 1 further comprises a condensation chamber 3, which is configured to allow the evaporated water to condense therein as fresh water.

The condensation chamber 3 and the evaporation chamber 2 are separated by a water permeable separation panel 8. The separation panel 8 is configured to allow the water vapor obtained by evaporating salt water in the evaporation chamber 2 to move from the evaporation chamber 2 to the condensation chamber 3. The fresh water obtained in the condensation chamber 3 is led down to a fresh water outlet 80, which may be connected to the fresh water tank 111 and/or the fresh water pipe 109. As mentioned above, the waste product of the desalination process is brine, which is removed from the evaporation chamber 2 through the brine outlet 7. The brine outlet 7 may comprise a controllable slide valve 70, which is configured to control the outflow of brine from the evaporation chamber 2. The brine outlet 7 may be connected to the brine tank 110 and/or the brine pipe 107. It is noted that the slide valves 60,70 may be controlled such that the (atmospheric) pressure in the evaporation chamber 2 is lowered, such that the boiling point of the salt water SW is lowered as a result thereof.

Accordingly, less energy is required to evaporate the salt water SW, as its boiling point is reached earlier.

The unit 1 may be located within a structure 11, for instance a structure 11 being part of a desalination plant 100. Furthermore, as multiple units 1 may be stacked (see Figure 1) or otherwise placed adjacent to each other, the unit { may be provided with mounting brackets 12. Accordingly, another desalination unit I may be mounted to the mounting brackets 12. Naturally, mounting brackets 12 may be provided at any location on the unit 1, e.g. on the top, bottom, or side walls of the housing 10 of the unit 1. Still referring to Figure 2, the salt water (e.g. seawater) SW, also called saline water, flows through the inlet 6 into the evaporation chamber 2. Before flowing through the inlet 6, the salt water SW may be pre-heated by a pre-heating element 5. The pre-heating element 5 obtains the salt water through the pre-heating element inlet 52, after which the salt water SW runs through a heating pipe 50 of the pre-heating element.

The heating pipe 50 may be heated by an additional heating element 51 disposed on or near the heating pipe 50. The outlet of the heating pipe 50 is connected to the inlet 6 of the evaporation chamber 2, such that pre-heated salt water SW may enter the evaporation chamber 2 through the inlet 6. As seen in Figure 2, the evaporation chamber 2 is inclined with respect to a gravitational vector G, accordingly the salt water SW flows along a lower wall 4 of the evaporation chamber 2. The lower wall 4 is provided with at least one heating element 40, which is configured to heat the lower wall 4 and therefore the salt water SW flowing along the lower wall 4. Accordingly, the salt water SW evaporates, such that water vapor WV is formed in the evaporation chamber. As the separation panel 8 is water permeable, the water vapor WV may move from the evaporation chamber 2, through the separation panel 8, to the condensation chamber 3. The water vapor WV condenses on or in the separation panel 8, such that liquid fresh water is obtained. Figure 3 further elucidates the desalination process of the desalination unit 1, and shows a transverse cross-section of the desalination unit 1, as indicated by the dashed line (FIG. 3-FIG.3) in Figure 2. Referring to Figure 3, the salt water SW flows along the lower wall 4 of the evaporation chamber 2, such that it is effectively heated by the heating element 40, which may be provided with vanes (not shown) which are disposed substantially perpendicular to the lower wall 4 and increase the contact surface with the salt water SW. When the salt water SW has been sufficiently heated, it will (at least partially) evaporate by which water vapor WV is obtained. The water vapor WV will rise to the water permeable separation panel 8, which is provided with capillary tubes 84. The water vapor WV may condense on the separation panel 8, at the receiving surface 83 and/or the expelling surface 82 thereof, and/or in the separation panel 8, and more specifically in the capillary tubes 84. Due to the capillary action CA of the capillary tubes 84 on the water (vapor) it will rise to the expelling surface 82 of the separation panel 8. As shown in Figure 3, the separation panel comprises two inclined panels (first and second inclined panels) which connect to a gutter 81. Alternatively, the gutter 81 (also called gully) may be formed by the two panels without a distinct gutter 81. Due to the force of gravity the fresh water, also called desalinated water DW, (condensed water vapor) will run along the two inclined panels to the gutter 81, wherein the desalinated water DW collects. With reference to Figure 2, the separation panel 8 is inclined with respect to a gravitational vector G, such that the desalinated water DW in the gutter 81 rans down, along the gutter 81, to the fresh water outlet 80 under the force of gravity. The inclined panels may be provided with grooves (not shown) and/or corrugations on the expelling surface 82 thereof, which grooves and/or corrugations run in direction of the gutter 81 so as to guide the condensed desalinated water DW to the gutter 81. As mentioned above, the evaporation chamber 2 and condensation chamber 3 are preferably contained within a (preferably airtight) housing 10.

Apart from the heating element 40 in the lower wall 4 of the evaporation chamber 2, and possibly the pre-heating element 5, the present desalination unit 1 and desalination plant 100 consume very little power.

The salt water SW enters the desalination unit 1 under the force of gravity (water pressure), the water vapor WV is transported from the evaporation chamber 2 to the condensation chamber 3 by means of capillary action CA, the obtained fresh water DW exits the condensation chamber 3 under the force of gravity, and the brine exits the evaporation chamber 2 under the force of gravity.

Accordingly, transport of the water in its various phases (salt water SW, water vapor

WV, and desalination water (or fresh water) DW) requires little energy and virtually no moving parts.

The above description of the attached drawings is provided merely for illustrative purposes to

IO contribute to comprehension of the present invention, and is not intended to limit the scope of the appended claims in any way or form.

Claims

Claims I. Desalination unit for desalination of saline water, such as seawater, comprising: an evaporation chamber arranged to receive the saline water through an inlet, and arranged to at least partially evaporate the saline water to obtain water vapor in the evaporation chamber, and - a condensation chamber arranged to receive desalinated water, - characterized in that the evaporation chamber and the condensation chamber are separated by a water-permeable partition panel arranged to collect the water vapor and having a receiving surface and an ejection surface, the receiving surface facing the evaporation chamber facing and arranged to receive the water vapor from the evaporation chamber, and wherein the ejection surface faces the condensation chamber and is arranged to expel the water vapor as desalinated water into the condensation chamber.

The desalination unit according to claim 1, wherein the partition panel is provided with capillary tubes extending from the receiving surface to the ejection surface such that the water vapor can enter the capillary tubes at the receiving surface, and is ejected as desalinated water at the ejection surface.

A desalination unit according to claim 2, wherein the partition panel comprises about 10 - 1000 capillary tubes per cm, more preferably about 100 - 500 capillary tubes per cm.

A desalination unit according to any one of the preceding claims, wherein the desalination unit is oriented such that the briny water in the evaporation chamber does not come into direct contact with the partition panel.

A desalination unit according to any one of the preceding claims, wherein the partition panel is tilted with respect to a gravitational acceleration vector such that an outwardly pointing perpendicular vector of the ejection surface comprises a component opposite to the gravitational acceleration vector.

The desalination unit of claim 5, wherein a wall of the evaporation chamber opposite the partition panel is a bottom wall of the desalination unit, and wherein the saline water flows along the bottom wall of the desalination unit.

A desalination unit according to any one of the preceding claims, wherein a salt water inflow rate through the inlet is balanced with a salt water evaporation rate such that the salt water in the evaporation chamber does not come into direct contact with the partition panel.

The desalination unit according to any one of the preceding claims, wherein the partition panel is formed to form a trough on the discharge surface side thereof such that the desalinated water is collected in the trough.

A desalination unit according to any one of the preceding claims, wherein the evaporation chamber further comprises a heating element adapted to heat the saline water to obtain the water vapor.

A desalination unit according to claim 9, wherein the heating element is provided at least at one wall of the evaporation chamber opposite the partition panel.

A desalination unit according to claim 9 or 10, wherein the heating element comprises fins to increase a contact area between the heating element and the saline water.

A desalination unit according to any one of the preceding claims, wherein the inlet comprises a preheating element arranged to preheat the saline water before it reaches the evaporation chamber.

A desalination unit according to any one of the preceding claims, further comprising a desalinated water outlet connected to the condensation chamber, arranged to allow the desalinated water to flow out of the condensation chamber.

A desalination unit according to any one of the preceding claims, further comprising a brine outlet connected to the evaporation chamber, arranged to allow the brine formed by partial evaporation of the brine water to flow out of the evaporation chamber.

The desalination unit of claim 14, wherein a brine inflow rate through the inlet is balanced with a brine outflow rate through the brine outlet such that the saline water in the evaporation chamber does not directly contact the partition panel.

A desalination unit according to at least claims 7 and 15, wherein the brine inflow rate, the brine evaporation rate, and the brine outflow rate are balanced such that the brine water in the evaporation chamber does not come into direct contact with the partition panel.

A desalination unit according to any one of the preceding claims, further comprising a desalinated water storage tank connected to the condensation chamber and adapted to store the desalinated water from the condensation chamber.

A desalination unit according to any one of the preceding claims, further comprising an elongate housing, wherein the evaporation chamber and the condensation chamber extend longitudinally of the housing, substantially the full length of the elongate housing.

A desalination unit according to any one of the preceding claims, further comprising pressure control means adapted to adjust an air pressure in the evaporation chamber.

A desalination unit according to claim 19, wherein the pressure control means comprise at least one controllable inlet valve which is included in the inlet of the desalination unit.

A desalination unit according to at least claim 14, and claim 19 or 20, wherein the pressure control means comprise at least one controllable inlet slide received in the brine outlet of the desalination unit.

A desalination unit according to any one of claims 19 - 21, wherein the pressure control means comprise a vacuum pump, which is adapted to lower the air pressure in the evaporation chamber.

A desalination unit according to any one of the preceding claims, wherein the inlet further comprises a pump adapted to pump the saline water into the evaporation chamber.

24. Desalinated water obtained by desalination by means of a desalination unit according to any one of the preceding claims,

A desalination plant comprising a plurality of desalination units according to any one of the preceding claims 1 - 23.

The desalination plant of claim 25, wherein the plurality of desalination units are at least partially submerged in a briny body of water.

The desalination plant of claim 26, wherein the saline water body is a sea or lake.

A desalination plant according to any one of claims 25 to 27, further comprising a shared desalinated water storage container connected to a plurality of condensing chambers of the plurality of desalination units, and arranged to store desalinated water. of the plurality of condensing chambers.

A desalination plant according to any one of claims 25 to 28, further comprising a raised platform extending above the plurality of desalination units and arranged to be accessible to persons.

A desalination plant according to any one of claims 25 to 29, wherein the plurality of desalination units are arranged to form channels therebetween, which channels are arranged to receive a portion of the saline water to cool the condensation chamber by means of the saline water.

31. Desalinated water obtained by desalination by means of a desalination installation as claimed in any of the claims 25-30.

32. A method of desalination of briny water to obtain fresh water, comprising the steps of:

- providing a desalination unit according to any one of claims 1 to 23; - receiving briny water in the evaporation chamber of the desalination unit; - heating the briny water to obtain water vapor in the evaporation chamber; - receiving the water vapor in the condensation chamber as desalinated water, by passing the water vapor through the partition panel of the desalination unit; and - collecting the desalinated water in the condensation chamber as being fresh water.

33. Desalinated water obtained by the method according to claim 32.