WO2011003874A1

WO2011003874A1 - Pv/t systems in water treatment systems

Info

Publication number: WO2011003874A1
Application number: PCT/EP2010/059574
Authority: WO
Inventors: Markus Spinnler; Alexander Kroiß
Original assignee: Technische Universität München
Priority date: 2009-07-06
Filing date: 2010-07-05
Publication date: 2011-01-13
Also published as: DE102010004874A1

Abstract

The present invention relates to a system for desalinating water comprising a photovoltaic system (3), wherein the system is configured such that the water (0) to be desalinated is heated by the waste heat of the photovoltaic system. The invention further relates to a method for desalinating water, wherein the water (0) to be desalinated is heated by the waste heat of a photovoltaic system (3).

Description

PV / T systems in water treatment systems

The invention relates to a system for desalination of water comprising a photovoltaic system, wherein the system to be desalinated water by the waste heat of

Photovoltaic system warmed up. In particular, this heating of the water in

Water treatment systems through a PV / T system (system, with the jjhotovoltaische and thermal energy can be obtained) can be realized. Such systems may e.g. used for seawater desalination, v.a. also together with membrane processes in which it is advantageous that the water to be desalinated has a certain elevated temperature before the actual treatment.

The invention relates to the use of PV / T systems for the energy supply of water treatment plants with membrane technology and is aimed primarily at small, energy self-sufficient systems in the decentralized area. In the following, plants for the desalination of seawater and brackish water and for the treatment of contaminated surface and well water are referred to as water treatment plants. The combination of PV / T systems and water treatment plants is completely new and has great technical and economic potential:

_* Enormous increase in drinking water production

_* Alternative to pressure recovery systems

_* Sales potential of approx. € 300 million per year

In certain system configurations, eg when combining reverse osmosis (RO) with PV / T, an increase in drinking water production of approx. 35 to 40% is realistic compared to purely PV-operated systems. This means that about 25 to 30% of the PV module area can be saved, assuming that the considered PV / T-powered and PV-powered plants produce equal amounts of drinking water. The investment costs for PV / T systems are about 10% higher than those of the PV systems. This means that the use of PV / T systems instead of PV systems for powering RO systems seems economically reasonable.

The use of PV / T systems in water treatment can also be seen as a serious alternative to previous pressure recovery systems whose purpose is to reduce the energy consumption of a desalination plant. If the excess yield of drinking water is converted into a comparable energy saving through the use of PV / T systems, an additional yield of 35% can be interpreted as an energy recovery of 25%. Although PV / T systems do not reach the dimensions of pressure recovery systems (with energy savings of 65 to 75%), these are unprofitable for small systems, so that the use of PV / T systems makes sense in this area.

The problem of drinking water is increasingly becoming one of the most acute problems in the world. The United Nations forecasts that by 2025, two-thirds of the world's population will be short of drinking water. Although almost two-thirds of the earth is covered with water, according to UNESCO, only about 0.02% is available to humans as fresh water. Not least because of this, water treatment and especially seawater desalination is a very promising technology to solve this problem. Much of the underserved live in developing rural areas, cut off from any infrastructure. This also means that a reliable access to the electrical energy supply via a power grid is not available. Therefore, self-sufficient desalination plants have to be developed. Because in countries such as Africa or India, where drinking water is particularly scarce due to periods of drought. the solar supply is very high, it makes sense to supply water treatment plants with solar energy. It is known that water treatment plants, especially reverse osmosis plants can be operated with electricity generated by solar cells, which, for example, from ES000002299396A1, CNOOOl 01337749 A or WO2006067240 shows. The electric current thereby drives all machines necessary for the desalting process, for example pumps or systems for water pre-treatment and subsequent water treatment. The problem that solar energy does not allow a constant power supply to the system is achieved here by means of storage systems for electrical energy, especially batteries or accumulators. A disadvantage of the power supply with solar energy are the high investment costs for the photovoltaic. These systems use solar energy exclusively electrically.

It is also known that the performance of the reverse osmosis membranes, which filter the salt from the seawater, is temperature dependent. The higher the salt water temperature, the more permeate can be produced. The "recovery ratio", ie the ratio of permeate flow to raw water flow (in this case raw water is called seawater to be desalinated), becomes larger, meaning that more permeate can be recovered from a given raw water flow The increase in temperature is limited by the material properties of the membranes to temperatures of 40 ^° C. to 45 ^° C. There are various ways of preheating the raw water to these temperatures.

In US020050236309A1 seawater, which has been heated, for example, as cooling water in a power plant to temperatures above 40 ⁰ C, mixed with cooler seawater to maintain the temperature limit of 4O ⁰ C. This seawater is then desalted in a reverse osmosis system. From CN000101318724A it is known that thermal solar collectors are also suitable for preheating the salt water to temperatures of 40 ⁰ C to 45 ⁰ C. The solar energy is used exclusively thermally.

Such systems have the disadvantage that they can not be used energy self-sufficient. Power plants that use seawater as cooling water, and electricity from the conventional power grid are not available in all drinking water poor regions. In addition, fossil energy sources for power generation are not only expensive, but also only limited available. The preheating of salt water also makes sense in seawater desalination based on membrane distillation. However, the temperature levels are then not limited as in the reverse osmosis to 40 ⁰ C, instead, temperatures of 80 to 85 ⁰ C are required. This is associated with limitations on the electrical efficiency of the photovoltaic modules. Existing PV / T systems also can not fully provide the required thermal power. Nevertheless, a combination of PV / T collectors with desalination plants based on membrane distillation is conceivable. Publications on this topic are currently unknown.

Similar results as for the example of reverse osmosis are to be expected for the combination of P V / T-Sy blocks with nanofiltration, ultrafiltration or microfiltration systems for the treatment of contaminated surface or well water. The pressures required on the raw water side are far lower than in reverse osmosis, which increases the raw water mass flow and thus the thermal efficiency of PV / T systems will be slightly less favorable than in reverse osmosis.

The object of the invention is to find a way to operate water treatment plants, especially those with membrane technology, energy self-sufficient with the help of solar energy at a relatively low cost. A further or additional object is to improve the existing methods and systems and to avert the disadvantages of the prior art.

This object is solved by the features of claim 1.

The invention provides a system for water treatment with a photovoltaic system ready, the waste heat of the photovoltaic system in operation, the raw water for later Preheating treatments.

A P V / T system or a P V / T system is understood, for example, as the combination of a photovoltaic system (PV) with a thermal solar collector (T) in a structural unit. This applies to all systems and / or systems that can simultaneously generate electrical and thermal energy from solar energy. A characteristic of conventional PV modules is that as the solar irradiance increases, the module temperature increases and the electrical efficiency drops by about 0.5% per K. In so-called hybrid PV / T systems, this increase in temperature can be used to heat a fluid (usually water or air). A thermal efficiency of 45 - 65% is possible. At the same time, the photovoltaic module, e.g. through the water to be desalinated, cooled, which has a positive effect on the electrical efficiency of the photovoltaic module. The solar energy is thus used not only electrically, but also thermally by the photovoltaic modules of the system, so that a PV / T system with photo of Italian and simultaneous thermal application is present. Overall, thus also results in a higher overall efficiency of the system for water treatment. The use of PV / T systems in the field of water treatment is novel and can contribute to solving the global drinking water problem.

The present invention relates to a system for desalination of water, the system comprising a photovoltaic system. The system is configured to heat the water to be desalinated by the waste heat of the photovoltaic system. The system is preferably in addition to the use in the desalination of seawater also generally for water treatment in general advantageous.

The term "desalination" is the term for the extraction of drinking water or process water from seawater by reducing the salt content. "Desalting" can refer to several processes that remove salts and minerals from the water, especially to extract drinking water.

The system for desalination or water treatment comprises a photovoltaic system and in one embodiment may comprise a pumping system and / or supply lines for the water to be desalted or treated (i.e. the raw water). The

Feeder lines can be particularly suitable here. Salt water and are e.g. made of a salt water resistant material such as a plastic

(For example, polypropylene, polyethylene, polytetrafluoroethylene (PTFE), synthetic resin, etc. Also, plastics with fillers such as metals or ceramics for increasing the

Thermal conductivity of the plastic are conceivable). The pump system may be suitable for bringing the raw water to the photovoltaic system and / or from the photovoltaic system to a membrane unit described in more detail below. At the photovoltaic system, the raw water is heated by the waste heat from the photovoltaic system, while the raw water on the other hand can cool the photovoltaic system. The thus heated raw water can then be processed in the membrane unit.

The photovoltaic system may include, for example, one or more solar cells (photovoltaic cells). If several solar cells are provided, they can be arranged via an electrical connection of the solar cells in a module (solar cell module, photovoltaic module). This module can then be designed such that a plurality of solar cells are connected in series and thus form a row of solar cells within the solar cell module, so that their output voltages add up. Also, several of these solar cell rows can be connected in parallel within the solar cell module. The photovoltaic system may include, for example, an array of solar cell modules, wherein in a well-defined way certain solar cell modules can be added or turned off. In one embodiment, the array includes solar cell modules of different performance. For example, a few solar cell modules may be constructed of solar cells that have the same efficiency even at higher heat-off temperatures than the solar cells of other solar cell modules reach, so that the raw water can be heated more when connecting these solar cell modules. By "waste heat" is meant in particular the heat emitted by the solar cell through the heat conduction and / or radiation.The more energy the solar cell has absorbed by the solar radiation, the more waste heat can be available.

This concept of turning on or off certain higher heat dissipation solar cell modules may be e.g. for the below explained membrane distillation, which can use higher preheated raw water, be beneficial. If, instead of membrane distillation, the system for the treatment of water using the reverse osmosis process is sensed, the existing solar cell modules, which have a greater waste heat, could be switched off. Thus, it is possible to easily adapt the system to the respective water treatment process. Also, with such a system, depending on the electrical energy required (e.g., for the pumping equipment), the full electrical power of the array, or just a particular portion of it, can be retrieved.

According to the present invention, the system is configured to heat the water to be desalinated by the waste heat of the photovoltaic system. In this case, the photovoltaic system generates not only electrical energy but also (eg inherent) thermal energy. The heating of the water can be done in particular by the fact that the system has means to bring to be desalinated (or in general: the water to be treated) close to the photovoltaic system. For example, this can be done by hoses, which are arranged on at least one of the side surfaces of the photovoltaic system or of the solar cell module, in particular on its rear side (the side facing away from solar radiation). In one embodiment, these hoses may be arranged in loops / loops or in any other pattern, for example in order to use a heat radiating surface of the photovoltaic system or of the solar cell module as effectively as possible. In this way, the raw water conducted through the hoses can also cool the photovoltaic system or the solar cell module, for example around the Check efficiency accordingly. The hoses may for example be made of a salt water resistant material, for example of a plastic.

In one embodiment, conventional P V / T plants can be used to heat the water to be treated, preferably salt water. In this case, a heat exchanger is preferably provided, which heats the water to be treated by another fluid from which the water to be treated absorbs energy in the heat exchanger. In this way, the water to be treated can be indirectly, e.g. over another fluid, to be heated.

The PV / T systems described here, which are used in conjunction with water treatment plants with membrane technology, thus generate both electrical and thermal energy (and heat a fluid for example with the aid of this thermal unit) with the aid of solar cells and use the latter to heat the water to be treated. It does not matter how this system, referred to as a PV / T system, is constructed. All systems are recorded, independent of

(a) a material of solar cells (solar cells of monocrystalline polycrystalline silicon, thin-film cells, dye (Gräzel) solar cells, organic solar cells, etc.),

(b) a material of the absorber and heat exchanger of the thermal unit

(Metals such as copper, plastics, ceramics, etc.),

(C) a geometry of the PV / T system (flat plate collectors, concentrating systems, etc.),

(d) a geometry of the thermal unit located behind the solar cells

(Duct or tubular heat exchanger, etc.),

(e) a number of any covers that are placed over the solar cells (none, one, more),

(f) a material of the covers (glass, teflon, plastic, etc.),

(g) any working fluid flowing in the PV / T system (water, air, ETC.),

(h) a type and a material of the insulation used,

(i) use of mirrors to concentrate sunbeams. Rather, the above alternatives represent preferred embodiments.

As a disadvantage of PV / T systems outside the technical field of water treatment was previously considered that with a comparatively good electrical efficiency flowing in the PV / T collector fluid can be heated only to low temperature levels. A good electrical efficiency can be guaranteed PV module temperatures up to 40 ⁰ C. This in turn means that a circulating behind the solar cell cooling fluid can reach temperatures of a maximum of 3O ⁰ C to 40 ⁰ C. However, this temperature level can be too low for a conventional PV / T application in the field of process water, process heat or heating without additional heat support (eg by means of a separate solar collector).

One field of application that has not yet been developed is the use of PV / T systems for supplying energy to water treatment plants as described in the invention. For example, the current generated by the solar cells can drive the pumps for the necessary raw water flow, as described above. Due to the simultaneous thermal application of the photovoltaic system, the raw water is preheated, whereby it can be heated to temperatures up to 40 ⁰ C to 45 ⁰ C. This temperature level is, as already explained above, at the same time the upper limit for the water temperatures in membrane plants, since the majority of the membranes are destroyed at higher temperatures.

Thus, the present invention provides a simpler and thus more cost-effective, with only a photovoltaic system (PV / T system) operated water treatment system available. In order to estimate the technical potential of systems according to the invention with PV / T-powered umkelirosmoseanlagen for brackish water and seawater desalination, a simulation for 16 different cases has been implemented and carried out (see Spinnler, M., Kroiß, A., "potential analysis for integrated brine heating In solar powered water treatment plants, "Internal Feasibility Study" Weather data from Almeria and Puerto Rico were used to simulate locations of two different latitudes, Almeria representing a Mediterranean climate and Puerto Rico a tropical climate, with analyzes for two different saltwater sources: Water from the open sea on the one hand, and deep well water on the other hand, in order to make a statement about the added value of each of these PV / T-plane plants, the systems considered were equipped with a corresponding PV-operated plant without thermal utilization according to the invention For a PV / T-RO system according to the invention, the following results were obtained: Due to the preheating of the raw water and the cooling of the solar cells, an increase in permeate production of about 35 to 40% can be achieved. This would save about 25 to 30% of PV module area, assuming that the plants in question should produce the same amount of permeate.

The investment costs for PV / T systems with photovoltaic and thermal applications are about 10% higher than those of pure PV systems, in which only electrical energy is to be utilized. This means that the use according to the invention of PV / T systems instead of PV systems for the power supply of reverse osmosis systems makes economic sense, after all, 25 to 30% of the PV module area can be saved. This finding can also be transferred to pure filtration processes for the treatment of contaminated surfaces or well water. The potentials are similar here, whereby a slightly lower thermal efficiency of PV / T systems could be expected compared to RO systems. The use of a photovoltaic system using its waste heat is thus of great advantage in the present technical field of water treatment, in particular water desalination.

Known photovoltaic systems have been used for water treatment purposes only to supply the power for the operation of the treatment system. By heating the solar cells by solar radiation, however, the efficiency of the solar cell can be significantly reduced, so that cooling of the solar cells, usually by air or water, may be necessary.

This is exploited by the present invention in that the water to be treated (for example, to be desalinated) can be heated by the waste heat of the solar cells and can thus be better adapted to the requirements of the following treatment steps. Thus, an optimal operation of both the solar cell and a subsequent treatment plant can be achieved in an advantageous manner.

Existing systems for water treatment systems use the photovoltaic system only to generate electricity, without using the resulting thermal energy.

The previous teachings with regard to the thermal energy development in sunlight on a solar cell go in a completely different direction: the heat radiation of the solar cell was usually equalized by appropriate cooling as much as possible, while the present invention makes use of this thermal energy.

In one embodiment, the photovoltaic system is configured to provide necessary electrical energy to operate the system. In this way, the system, preferably independently of other energy sources, the water treatment, in particular the desalination water perform. Thus, the system is particularly well suited for use in developing countries and remote power or other energy networks.

In one embodiment, the system includes a membrane unit configured to reduce the salinity of the heated water.

A membrane unit here is any device that includes a membrane and is configured to treat raw water. Possible methods using such a membrane unit are e.g. the reverse osmosis, the membrane distillation, the

Nanoflutration, ultrafiltration and microfiltration. Depending on the used

Treatment process, in particular desalting process, is the membrane of

Membrane unit is a semipermeable membrane and has a pore size of 0.1 to 5 nm (for example for reverse osmosis) and / or 0.05 to 0.5 mm (membrane distillation). In one embodiment, the membrane may be hydrophobic, e.g. in use as

Membrane for membrane distillation.

For example, water treatment plants, in particular water desalination systems, based on membrane processes operated with P V / T systems, require semipermeable membranes for the filtration of the raw water. Various membranes can be used in a membrane unit of the system according to the invention. All conceivable membrane units which are suitable for carrying out a water treatment, in particular a water desalination, are possible in the system. The membrane unit of the system can thus be independent of

(a) a certain type of membrane (spiral wound membranes, hollow fiber membranes, plate membranes, etc.) and membrane material,

(b) a mode of action (reverse osmosis, membrane distillation, nanofiltration, ultrafiltration, microfiltration, etc.), (c) a number of membranes,

(d) an arrangement of the membranes (parallel or in series)

(e) a composition of the fluid flowing through the membrane. Rather, the above alternatives represent preferred embodiments. In one embodiment, the membrane unit comprises a reverse osmosis system.

A variant of water treatment plants with membrane technology are so-called reverse osmosis plants. In a desalination of water, the salt is separated by membrane filtration under high pressure from the water. The remaining, pure water, the so-called permeate, can then be treated to drinking water.

In detail, in reverse osmosis (RO), the solution to be treated (e.g., the seawater) is subjected to high pressure to overcome the osmotic condition

Pressure, pressed by a semipermeable membrane. This membrane acts like a

Filter and passes only certain atoms and / or molecules and / or ions. This gives a separation of the original solution. Through the membrane filter can be e.g. Salt, bacteria, viruses, lime, and also certain poisons, e.g. Heavy metals, withhold.

In one embodiment, the membrane unit comprises a membrane distillation unit. Membrane distillation is based on a process where treated water is obtained by condensation after membrane filtration. For example, in a desalting process, a microporous and / or hydrophobic membrane can be used which only allows water vapor to pass but retains liquid water. On one side of the membrane is warm salt water (eg heated by the waste heat of the photovoltaic system) and on the other side a colder surface. Insists on the whole Length of the membrane a temperature difference, creates a water vapor partial pressure gradient, which causes water molecules from the warm to the cold side of the membrane and condense there. In the case of desalination based on membrane distillation, the use of PV / T systems may not provide the required thermal power completely, but preheating by means of such photovoltaic systems is still profitable and advantageously increases the heat output Efficiency of the overall system.

In one embodiment, the system may include thermal solar collectors.

For example, the raw water can be heated (preheated) by the waste heat of the photovoltaic system and then brought to an even higher temperature by the thermal solar collectors. In this way, particularly high temperatures for the raw water can be achieved, in particular temperatures at which the photovoltaic system would have too low an efficiency to still effectively generate electricity. In particular, such a system could be used in water treatment with a membrane distillation process in which higher raw water temperatures of about 8O ⁰ C would be beneficial.

In one embodiment, the system does not include any additional means for heating the water to be desalted, in particular no solar collectors.

Thus, in one embodiment, the system only comprises the photovoltaic system for heating the raw water (i.e., the water to be desalinated and / or treated).

For example, no thermal solar collectors are provided to (further) heat the raw water to reach higher temperatures for the raw water before this is processed in the membrane unit (eg by reducing its salt content). "No additional means for heating the water to be desalted" means in particular that no thermal energy generating means is provided that non-thermal energy specifically into thermal energy converts to then heat the water to be desalinated.

In this way, a particularly simple and thus cost-effective system can be provided, in which the photovoltaic system required for the power supply is also used as a thermal component of the system to heat the raw water.

In particular, such a system could be used in water treatment with a reverse osmosis process in which raw water temperatures of 4O ⁰ C to 45 ⁰ C would be beneficial and can already be achieved by the waste heat of the photovoltaic system.

As described, the present invention utilizes the waste heat from solar cells or a photovoltaic system in order to heat the water to be treated directly or indirectly and thus to enable an optimized operation of the treatment or desalination plant. While retaining this advantage, the invention also makes it possible to cool the photovoltaic system by means of the water to be desalinated or reprocessed, and at the same time to optimize the operation of the photovoltaic system. In a preferred embodiment, it is possible that the water to be desalinated or to be treated or to be purified cools the photovoltaic system.

By cooling the photovoltaic system with the colder raw water their effectiveness can be ensured and their efficiency can be kept constant. In one embodiment, the system includes an energy buffer coupled to the photovoltaic system and configured to compensate for temperature variations in the waste heat. The energy buffer can be in the form of a heat accumulator, wherein the heat accumulator optionally stores excess heat energy from the photovoltaic system. Excess heat energy can be present, for example, if not all the waste heat is needed for heating a certain amount of water to be treated (for example to be desalted). Heat storage can be, for example, long-term and / or Kurzzeitspeieher. Long-term storage can be, for example, hot water heat storage (insulated container with water). Also thermochemical (eg on the basis of silica gel and / or zeolite) and latent heat storage (salts or paraffins melt when heat is applied and give exactly this received heat energy when solidifying again) can be used as a long-term storage. Short term storage stores heat only for a few hours or days. For this purpose, for example, self-standing water storage tank or thermochemical heat storage can be used as described above.

Thus, the heat accumulator may optionally assist the photovoltaic system in the heating of particularly cool raw water and compensate for temperature fluctuations in a simple manner.

In one embodiment, the system includes a buffer for the heated water. For example, heated water can be fed from the buffer to the membrane unit, especially if water to be desalinated or water to be treated can not be heated quickly enough and / or in an insufficient amount by the photovoltaic system.

In this way fluctuations in the water supply of the membrane unit can be reduced. In one embodiment, the system comprises a battery (accumulator) for storing or buffering electrical energy. For example, part of the electrical energy received / generated by the photovoltaic system can be stored in the battery. In particular, with insufficient solar radiation to the photovoltaic system required for operating the system electrical energy of the battery can be removed.

In particular, fluctuations in the power supply of the system can be reduced in this way. In a particular embodiment, therefore, a substantially constant operating pressure can be achieved.

In one embodiment, the system includes a heat exchanger. For example, the heat exchanger may be capable of preheating the raw water prior to entering the photovoltaic system, and / or heated water, in particular before and / or after treatment / desalination, e.g. to use for cooling the photovoltaic system.

In this way, the efficiency of the system can be further increased. Also, cooling with fresh water can be realized in this way, when fresh or desalted water is fed to the photovoltaic system for cooling. The water to be desalinated is then preferably heated in a heat exchanger by the heated cooling water. In particular, water that has been heated by the PV / T plant may heat the raw water, preferably via the heat exchanger. In one embodiment, components of the system are in particular made of a salt water-resistant material such as a plastic (for example polypropylene, polyethylene, polytetrafluoroethylene (PTFE), synthetic resin, etc. Also plastics with fillers such as metals or ceramics for increasing the thermal conductivity of the plastic are conceivable) and / or at least partially coated with and / or treated accordingly. These components can be used for Example components of the system that come into contact with salt water, especially hoses, supply lines, etc.

The present invention also relates to a process for desalination of water. The method comprises the following step: (a) heating the water to be desalinated with the waste heat of a photovoltaic system.

In particular embodiments of the method, the above descriptions and explanations of the features of the system according to the invention and the concept of the invention explained in the above context also apply to the method according to the invention described here and below.

In one embodiment, the photovoltaic system for desalting water supplies necessary electrical energy, e.g. the electrical energy necessary to operate the water treatment system (e.g., the desalination system).

For example, the electrical energy generated by the photovoltaic system can be used to deliver the water to be desalted, e.g. via lines by means of pumps to the photovoltaic system to bring, where the water is preheated. Further, the power generated by the photovoltaic system may be used to power other system components, such as power supplies. The membrane unit to supply to perform the actual water treatment / desalination of the preheated water.

In an embodiment, the method comprises the following step: (b) reducing the salinity of the heated water in a membrane unit.

In one embodiment, in step (b), the heated water is filtered under high pressure through a semipermeable membrane. For example, the heated water can be desalted in a reverse osmosis process.

In one embodiment, in step (b), steam of the heated water is separated from saline water by a semipermeable hydrophobic membrane.

For example, the heated water can be desalted in a membrane distillation process. In one embodiment, the temperature of the heated water is controlled and / or adjusted by means of an energy buffer on the photovoltaic system.

For example, the energy buffer may be coupled to the photovoltaic system. Further, the energy buffer may be configured to compensate for temperature variations of the waste heat to thereby control and / or set (to a particular value) the temperature of the heated water.

The present invention also relates to a computer program product comprising at least one computer readable medium having computer executable instructions for performing the method steps discussed above.

For example, the computer program product may include a computer program that is capable of controlling and / or controlling the progress of the water treatment. In one embodiment, the computer program may control and / or control the operation of the photovoltaic system system and optionally also the membrane unit. For example, at the end of the computer program, the photovoltaic system may be controlled such that solar cell modules are turned on or off at certain times, that the generated current is used for other means in the system (eg for a pump plant) and that the heated one Water reaches the membrane unit and there treated accordingly and optionally in Connection will be treated further. In one embodiment, the computer program product may be adapted to control certain sensors in the system, for example to obtain data on the temperature and / or salinity of the heated water and / or raw water, and in response thereto a particular procedure for water treatment.

The present invention further relates to the use of PV / T systems both for the electrical power supply of the necessary for a plant for water treatment on the basis of membrane technology machines to operate electric power is needed, as well as for preheating the raw water to an optimum operating temperature and thus guarantee the highest possible efficiency of the membranes.

Fig. 1 shows schematically a water treatment system with a photovoltaic system. To illustrate, for example, how a PV / T operated reverse osmosis system can be constructed, Figure 1 should serve. Figure 1 shows a possible system configuration, exemplified here as a combination of PV / T systems (a PV / T system) with a reverse osmosis system / unit for solar desalination in a water treatment system, in particular in a desalination system.

For the reverse osmosis process, the membranes are the basic building block 8. The high-pressure pump 7 increases the pressure of the salt water 0 before the membrane inlet to about 60 bar, depending on the salt content. The pump 7 is supplied with the electric power generated in the PV / T systems 3. In order to cushion excessive fluctuations in the energy supply, an accumulator 6 is used as a buffer for the electric current. The temperature dependence of the performance of the membrane should be exploited by preheating the raw water 0 in the PV / T collectors bzw.in the photovoltaic system 3. Between high-pressure pump 7 and the collectors 3 there is a hot water tank 5. This serves as a buffer for the heated raw water. In this way, large fluctuations in the water supply of the individual reverse osmosis units 8 can be avoided. The temperature at which the membranes work optimally is approximately 40 ^° C. In order to keep the temperature level approximately constant, it would be possible to install, in addition to the PV / T systems, optionally pure solar collectors 4 or means for heating the water to be treated / desalted ,

A variant to recover energy is indicated here with the heat exchanger 1. The temperature of the feed water (raw water) 0 is thus raised before entering the individual collectors 3, 4. Overall, an additional increase in drinking water production can be achieved. Whether the water pretreatment 2 is carried out before or after the heat exchanger 1 and the collectors 3, 4, is to be decided in the design of the system. The permeate 9 can be prepared, for example, by addition of minerals, pH correction, etc. 11 finally to drinking water 12.

In large plants, a second form of energy recovery is often used: The pressure recovery - it is due to high investment costs only in large plants economically viable. With such systems, energy savings of 65 to 75% are possible. If the excess yield of permeate stream is converted into a comparable energy saving through the use of PV / T systems, an additional yield of 35% can be interpreted as energy recovery of 25%. Although PV / T systems do not reach the dimensions of pressure recovery systems, the result is nevertheless very promising. The idea now suggests that PV / T systems can be used exactly where pressure recovery systems become unprofitable - especially in energy-self-sufficient small plants.

Beseichiϊiingsiiste Fig. 1:

(0) sea water / water to be treated / brackish water (eg from a deep well, a reservoir or directly from the open sea) (1) heat exchanger

(2) water pre-treatment (filtration, acid addition, and / or anti-scalants, etc.)

(3) PV / T systems

(4) Thermal solar collectors

(5) Hot water tank

(6) Battery (s) / accumulator (s)

(7) pump (e.g., 60 bar)

(8) reverse osmosis units (membranes)

(9) permeate

(10) Concentrate

(11) Water post-treatment (addition of minerals, pH correction, etc.)

(12) drinking water

Fig. 2 shows schematically another example of a water treatment system with a photovoltaic system. ^■ -

Also in Fig. 2, the membrane units 26 are the basic building block for the reverse osmosis process. The high-pressure pump 25 can increase the pressure of the salt water 20 before the membrane entry depending on the salt content, for example, about 60 bar. The pump 25 is supplied, for example, with electrical energy that is generated in the photovoltaic system 22, preferably a PV / T system. An accumulator 24 can be used as a buffer for electric power, in particular to cushion excessive fluctuations in the power supply. Similar to the example described above, the temperature dependence of the performance of the membrane units 26 is also preferably exploited here by the preheating of the raw water 20 in the photovoltaic system 22. Between the pump 25 and the photovoltaic system 22, a hot water tank 23 is preferably provided to serve as a buffer for the heated raw water. In this way, preferably large fluctuations in the water supply of the individual reverse osmosis units be avoided.

As already described in Fig. 1, preferably a water pre-treatment 21 is provided, e.g. to pre-filter the water to be treated, to adjust the acidity or to add anti-scalants. After the reverse osmosis process, the permeate 27 can then be treated, for example by adding minerals, and / or by a pH correction, etc. 28 finally to drinking water 29. The concentrate 30 separated from the permeate 27 in the membrane units 26 can, for example, ultimately be returned to the seawater or to a raw water reservoir 20.

Designation list Fig. 2:

(20) seawater / water / brackish water to be treated (eg from a deep well, a reservoir or directly from the open sea)

(21) water pre-treatment (filtration, acid addition, and / or anti-scalants, etc.)

(22) Photovoltaic system, preferably PV / T system

(23) Warm water tank

(24) Battery (s) / accumulator (s)

(25) pump (e.g., 60 bar)

(26) reverse osmosis units (membranes)

(27) permeate

(28) Water aftertreatment (addition of minerals, pH correction, etc.)

(29) Drinking water

(30) concentrate

The detailed description of the present invention, and more particularly the embodiments thereof, are given by way of illustration and are to be considered as illustrative and not restrictive. Features associated with a particular embodiment or a subclaim are described, may also be advantageous if they serve as features for other beschri planar embodiments or not described alternatives and / or equivalents or other dependent claims, even if they were not explicitly described in their context. Variations and modifications of the described embodiments and claimed subject matters are also included in the invention as one skilled in the art would have perceived having read the description and studying the figures and claims. The verb "comprising" in the specification and claims means that there may be other elements and / or process steps, and the indefinite article "a" does not exclude the plural.

Claims

PATENT CLAIMS

A desalination system comprising a photovoltaic system (3), the system being configured to heat the water (0) to be desalinated by the waste heat of the photovoltaic system.

A system according to claim 1, wherein the photovoltaic system (3) is configured to supply necessary electrical energy to operate the system

The system of claim 1 or 2, wherein the system comprises a membrane unit (8) configured to reduce the salinity of the heated water.

4. System according to claim 3, wherein the membrane unit (8) comprises a reverse osmosis system.

5. System according to one of claim 3, wherein the membrane unit (8) comprises a membrane distillation plant.

6. System according to any one of the preceding claims, wherein the water to be desalinated (0), the photovoltaic system (3) cools.

The system of any of claims 2-6, wherein the system comprises an energy buffer coupled to the photovoltaic system and configured Compensate for temperature fluctuations of the waste heat, and wherein the photovoltaic system (3) is a PV / T system.

8. A water desalination process comprising the following step:

(A) heating the water to be desalinated (0) with the waste heat of a photovoltaic system (3).

9. The method of claim 8, wherein the photovoltaic system (3) for supplying water desalination supplies necessary electrical energy.

10. The method of claim 8 or 9, comprising the following step:

(b) reducing the salinity of the heated water in a membrane unit (8).

The method of claim 10, wherein in step (b) the heated water is filtered under high pressure through a semipermeable membrane.

12. The method of claim 10, wherein in step (b) water vapor of the heated water is separated from saline water by a semipermeable hydrophobic membrane.

13. The method according to any one of the preceding claims, wherein the temperature of the heated water by means of an energy buffer (5) on the photovoltaic system

(3) controlled and / or adjusted.

14. Computer program product comprising at least one computer-readable medium with executable on a computer instructions for performing the method steps according to one of claims 8 to 13.