DE102013224351B4 - Device for generating service water - Google Patents

Abstract

The present invention relates to a device for producing industrial water from contaminated water, comprising a condensation tank (2) with a service water drain (4) and a process air drain (36), an evaporation tank (6) with a residual water drain (8) and a process air inlet (38) Controllable-permeability separator (10) forming a horizontal passage between the condensing vessel (2) and the evaporation vessel (6), a condenser (12) disposed in the condensing vessel and a contaminated water coolant inlet (14) and a coolant outlet (16) a heater (18) connected to the coolant outlet (16) and configured to heat the contaminated water; a spray device (20) connected to the heater (18) and arranged to heat the contaminated water into the evaporation tank (6) spray, and a controllable air conveyor Device (22) which is adapted to supply process air to the evaporation tank (6).

Description

The present invention relates to a device for recovering process water by desalination of seawater or salt water in general or purification of contaminated waters such as brackish groundwater or wastewater. The device should preferably be powered by solar energy.

State of the art

A known process for seawater desalination is based on the basic principle of the so-called wet-air distillation. This is also well suited for small, decentralized systems and the energy supply by solar energy.

Single-stage processes for solar thermal desalination of seawater are known in which the evaporator and condenser each have only at the top and bottom an air and water inlet or outlet. It can only be achieved a heat recovery of about 50%. However, the expenditure on equipment is relatively low, so that the use in structurally weak areas offers.

To achieve higher heat recovery, multiple stages of evaporation and condensation are required. This method is therefore often used in seawater desalination plants. For high-performance fossil-fueled plants, more than 12 stages and more than 96% heat recovery are possible. However, the equipment cost is very high in such systems. For structurally weak areas, such systems are therefore less suitable.

Another known method for the thermal desalination of seawater is the so-called multi-effect humidification / Dehumidification method (MEH). Systems based on the MEH process are based on thermal energy supply from low-temperature sources (eg solar collectors). The heat is supplied to a sealed desalination tank, in which the natural water cycle with evaporation and condensation is modeled.

Preheated seawater is further heated by the supply of solar energy and evaporated in a part of the desalting tank, whereby brine (brine) with concentrated salt content is deposited. In the other part of the desalting tank, the steam for condensing the distillate or service water is condensed by means of a cooler, the cold seawater is supplied as a cooling medium and this is preheated. This process runs in the cycle, with cold seawater and solar energy supplied and Brine and hot water are withdrawn.

By transferring the heat energy released when condensing on the supplied seawater, a large part of the heat energy used for evaporation in the process of condensation is recovered in the process and used for the preheating of the seawater. By preheating in turn, the energy is reduced, which is needed to further heat the seawater.

The publication DE 43 40 745 C2 uses such a wet air distillation process for hot water production.

However, this system has certain disadvantages. On the one hand, the evaporation takes place by applying heated sea or generally contaminated water to nonwoven or fabric towels, so as to increase the available surface area for evaporation. However, this requires that the contaminated water must not contain significant amounts of solids or suspended matter, otherwise the cloths would clog up quickly and thus become unusable. The system is therefore for cleaning polluted water with amounts of solids and suspended solids, eg. B. of brackish groundwater, not suitable.

Furthermore, it is a system with a process container without inner partitions. So there is no separation between the evaporation room and the condensation room. A control of the mass flows involved is therefore not possible. The method relies on a convection roller forming between the evaporation space and the condensation space. The performance of the plant is therefore limited by the volume of the process vessel needed to ensure this convection, which is modeled on nature. The air circulation takes place predominantly laminar.

The publication EP 2455343 A1 discloses an apparatus for purifying water, wherein water is divided into droplets by a sputtering apparatus and wherein the vaporized by the droplets Water vapor in a carrier air stream produced by the atomizer is transported along a circulation path via a demister, which removes any remaining droplets, to a condenser.

The object of the present invention is to provide an improved hot water production device based on the wet air distillation, which is more efficient for a given volume of the process vessel, d. H. can produce more process water per unit of time, and which nevertheless retains the fundamental advantages of the MEH process. The proposed device should continue to be suitable to process contaminated water with fractions of solids and suspended matter.

Brief description of the invention

• – einen Kondensationsbehälter mit einem Brauchwasserabfluss und einem Prozessluftabfluss;
• – einen Verdunstungsbehälter mit einem Restwasserabfluss und einem Prozessluftzufluss;
• – eine Trenneinrichtung mit steuerbarer Durchlässigkeit, die einen horizontalen Durchgang zwischen Kondensationsbehälter und Verdunstungsbehälter bildet;
• – einen Kondensator, der im Kondensationsbehälter angeordnet ist und einen Kühlmitteleinlass für verunreinigtes Wasser und einen Kühlmittelauslass aufweist;
• – eine Heizeinrichtung, die mit dem Kühlmittelauslass verbunden und eingerichtet ist, das verunreinigte Wasser aufzuheizen;
• – eine Sprüheinrichtung, die mit der Heizeinrichtung verbunden und eingerichtet ist, das aufgeheizte verunreinigte Wasser in den Verdunstungsbehälter einzusprühen; und
• – eine regelbare Luftfördereinrichtung, die eingerichtet ist, Prozessluft dem Verdunstungsbehälter zuzuführen
• – eine regelbare Luftleitung, die eingerichtet ist, Prozessluft im oberen Bereich, bevorzugt an der Oberseite des Verdunstungsbehälters abzuführen und dem oberen Bereich, bevorzugt der Oberseite des Kondensationsbehälters zuzuführen, um einen Teil der Luftmenge, bevorzugt etwa 8–10%, zwingend durch den Sprühstrahl der Sprüheinrichtung zu führen;

wobei die Durchlässigkeit der Trenneinrichtung an verschiedenen Positionen in der Trenneinrichtung unabhängig von im Wesentlichen geschlossen bis im Wesentlichen vollständig geöffnet steuerbar ist, so dass die Luftströmung innerhalb von Verdunstungsbehälter und Kondensationsbehälter dadurch gezielt so beeinflusst werden kann, dass die Luftströmung im Wesentlichen turbulent ist; und
wobei die Trenneinrichtung eine Jalousie mit mehreren horizontal verlaufenden Lamellen ist, wobei bevorzugt jede Lamelle einzeln steuerbar ist.According to a first aspect of the invention there is provided an apparatus for producing industrial water from contaminated water, comprising:

• - A condensation tank with a process water drain and a process air drain;
• - An evaporation tank with a residual water drain and a process air inlet;
• A controllable-permeability separator which forms a horizontal passage between the condensation container and the evaporation container;
• A condenser disposed in the condensation vessel and having a contaminated water coolant inlet and a coolant outlet;
• A heater connected to the coolant outlet and arranged to heat the contaminated water;
• A spraying device connected to the heating device and arranged to spray the heated contaminated water into the evaporation tank; and
• - A controllable air conveyor, which is adapted to supply process air to the evaporation tank
• - An adjustable air line, which is adapted to process air in the upper region, preferably at the top of the evaporation tank to dissipate and the upper area, preferably the top of the condensation tank to a portion of the amount of air, preferably about 8-10%, mandatory by the spray to lead the spraying device;

wherein the permeability of the separator at different positions in the separator is independently controllable from substantially closed to substantially fully open, such that the air flow within the evaporator and condensation containers can thereby be selectively controlled so that the air flow is substantially turbulent; and
wherein the separator is a blind with a plurality of horizontally extending slats, wherein preferably each slat is individually controllable.

With the device according to the invention, the amount of air circulated and the amount of brine and thus the power can be controlled specifically, the operating principle used in the invention is therefore referred to as Controlled Multi-effect Humidification / Dehumidification (CMEH). As a result of the air delivery device, substantially more process air per unit of time can be circulated over the same space requirement of the evaporation container and the condensation container, thereby allowing more water to evaporate. By means of the separation device with variably controllable permeability located between evaporation container and condensation container, the formation of a desired air circulation can be specifically influenced so that the air circulation takes place predominantly in the turbulent region. The advantages of the nearly stepless MEH process are retained despite a considerable increase in performance in the CMEH process.

The air circulation can be controlled so preferably about the top and bottom separately. In a preferred embodiment, the separating device is designed such that at each vertical position the permeability is independently controllable. As a result, the desired shape of the air roll, which is formed within the evaporation tank and condensation tank, driven by the air conveying device, can be influenced in a targeted manner.

The adjustment can be done by hand, but preferred is the control via a suitable drive.

A Venetian blind represents a very simple separating device, which can be controlled from essentially closed to substantially completely open. In addition to the degree of permeability, the air flow here can also be influenced by the orientation of the respective lamellae. For example, in the upper region of the evaporation tank, a substantially obliquely upward directed air flow available. Depending on the desired control, the lamellae can be aligned parallel to it, in order to achieve as undisturbed a flow as possible, or perpendicular thereto, if a more turbulent flow is to be achieved due to the higher resistance.

Due to the different water content of hot saturated air (340 g / m ³ at 85 ° C) and cold saturated air (30 g / m ³ at 30 ° C), the air requirement in the upper part of the evaporation and condensation tank is about 10 times lower than in the lower area. Accordingly, the air flow that can be controlled by the variable separator accordingly varies. By changing the amount of air and the amount of process water, the performance of the system can be regulated.

According to one embodiment, the air conveying device is a fan.

According to one embodiment, the process air outlet of the condensation tank is connected to the process air inlet of the evaporation tank, so that preferably a closed air circuit is created. Alternatively, however, the air circuit may be open, so that
Process air is taken from the environment of the device and returned to the environment after passing through the device.

According to one embodiment, the process air outlet and the process air inlet are each arranged in the lower region, preferably on the underside of the condensation container or the evaporation container.

• – eine regelbare Luftleitung, die eingerichtet ist, Prozessluft im oberen Bereich, bevorzugt an der Oberseite des Verdunstungsbehälters abzuführen und dem oberen Bereich, bevorzugt der Oberseite des Kondensationsbehälters zuzuführen.

According to the invention, the device further comprises:

• - An adjustable air line, which is adapted to dissipate process air in the upper region, preferably at the top of the evaporation tank and the upper area, preferably the top of the condensation tank supply.

This measure has the purpose of a part of the air amount, preferably about 8-10%, mandatory to pass through the spray. This ensures a very intensive humidification of the air. In addition, while the full beam with the entire entrained by the heated water heated heat energy is passed through only 8-10% of the amount of air. An outlet temperature of the air near the corresponding water inlet temperature can be achieved. The lower this temperature difference, the sooner a higher heat recovery or a higher efficiency can be achieved.

According to one embodiment, the heating device comprises a solar collector which is adapted to heat the contaminated water directly or via a heat exchanger.

Preferably, the plant is powered by solar energy, which is sufficiently available especially in areas such as the Sahara. As a result, the energy required to be supplied can be covered in a cost-effective and environmentally friendly manner. The water to be purified can be heated directly in the solar field to the required temperature, or it can be transferred by means of a heat exchanger, the heat energy to the contaminated water. The former allows a very simple construction with low losses. The latter makes it possible to use in the solar collectors another liquid, such as oil, so that there is a separation from the contaminated water.

• – einen Kühler, der zwischen den Restwasserabfluss und den Kondensator geschaltet und eingerichtet ist, das Restwasser abzukühlen und dem Kondensator zuzuführen.

According to one embodiment, the device further comprises:

• - A cooler, which is connected between the residual water drain and the condenser and arranged to cool the residual water and supply to the condenser.

The cooler has the task to cool the process water from the evaporation tank and feed it to the condenser. Cooling can be done using cold contaminated water, or alternatively through a cooling tower or chimney. The cooling power preferably corresponds to the heating power of the heater, so that a closed heat cycle is formed.

• – einen Wärmespeicher, der eingerichtet ist, Wärmeenergie zu speichern und bedarfsweise der Heizeinrichtung zuzuführen.

According to one embodiment, the device further comprises:

• - A heat storage, which is adapted to store heat energy and, if necessary, supply the heater.

In order to ensure, for example, in solar thermal energy supply to the plant operation outside the hours of sunshine, a heat storage can be provided for Caching of thermal energy is used. In the case of the use of solar collectors, the power or area must be increased accordingly. In general, the heat accumulator serves to temporarily store accumulating and / or economically usable heat energy only at certain times in order to provide it to the service water generating device as needed. This also applies to other forms of energy such as industrial waste heat etc.

Short description of the drawing

1 is a schematic view of a first embodiment of the invention;

2 is a schematic view of a second embodiment of the invention;

3 is a schematic view of a third embodiment of the invention;

4 is a schematic view of a fourth embodiment of the invention; and

5 is a schematic view of an exemplary pilot plant according to the invention.

Detailed description

In the following, reference is made, by way of example, to seawater or, in general, salt water as a possibility for contaminated water. Other contaminated waters with other undesirable ingredients than salt, especially those with shares of solids and suspended matter, but can be processed in the same way.

1 is a schematic cross-sectional view of a first embodiment of the present invention. An evaporator tank 6 The task is to bring the process air to a relative humidity of almost 100%, ie saturated, and a temperature of about 85 ° C. Salt water is added by means of a spraying device 20 finely distributed in the evaporator container 6 sprayed.

The water content at this temperature is then about 340 g / m ³ . The required amount of air for the transport of 1 m ^{3 of} water is therefore about 3000 m ³ / h in single-stage operation, in multi-stage operation about 6000 m ³ / h. The evaporator receives the required energy through 10 m ³ / h of process water (brine) with a temperature of, for example, 86 ° C. This temperature is achieved by preheating in the condenser and supplying additional heat energy, preferably solar energy. During condensation, for example, the process water cools to about 32 ° C, the released energy is transferred to the salt water used as a coolant, thereby achieving preheating and heat recovery.

In order to be able to transfer the heat energy from the process water to the process air, a large transition area between the two media is required. In an estimate, the following assumptions are made: Temperature difference between process water and process air: 3 ° C. Heat energy for the evaporation of 1 m ^{3 of} seawater: 700 kW. Heat transfer coefficient α: 0.05 kW / (m ² · ΔT). Required transition area: 4667 m ² .

The heat transfer or heat transfer coefficient is of crucial importance in seawater desalination, since it significantly influences the areas for cooling and evaporation. The above assumption would require a heat exchanger with a huge surface or a huge water surface, which is so unrealistic for a corresponding plant. In the prior art, this has been solved by the use of cloths or webs that provide surface enlargement but are problematic with suspended and solids.

According to the invention, this problem is therefore solved instead by Tropfenbesprühung. With suitable nozzles, the spray can 20 To produce such a large amount of smallest drops, which have a 10 times larger area of about 50,000 m ² . In this way, the evaporator container 6 generates a process air saturated with water. Not absorbed by the process air, concentrated salt water or Brine can by a residual water flow 8th from the evaporator tank 6 be dissipated.

By using a spraying device, there is no problem with water containing solid or suspended matter. The process water may therefore also have coarse particles, but the diameter should not be more than about 1/3 of the nozzle opening. The solids are filtered out during the process. This is a huge technical and economic advantage, since the filtering of such substances would otherwise be complicated and expensive.

• – Medikamentenrückstände;
• – Düngemittelrückstände und Giftstoffe;
• – Chemische Rückstände wie z. B. Farbstoffe.

The following pollutants contained in the process water are completely or partially filtered out in the process of the invention, these substances are usually very harmful to the environment:

• - drug residues;
• - fertilizer residues and toxins;
• - Chemical residues such. B. Dyes.

By filtering out even the finest solids, any radiation exposure is reduced.

Wastewater loaded with fine substances can be thickened with the device according to the invention to the extent that it can no longer be sprayed. The thus thickened wastewater can be removed separately and fed to a further treatment with conventional methods such as pressing, drying and combustion.

The water-saturated process air is horizontal from the evaporator tank 6 to the condensation tank 2 guided. Between the evaporator tank 6 and the condensation tank 2 is a separation device according to the invention 10 For example, a blind with a variety of slats 24 arranged. The blind 10 can the opening between evaporator tank 6 and condensation tank 2 from fully open to fully closed. In a preferred embodiment, each slat of the blind can be controlled individually. In the in 1 example shown, some slats in the lower half of the blind are closed, while all other slats are partially open. This allows the flow between Verdunsterbehälter 6 and condensation tank 2 be specifically influenced.

In the condensation tank 2 is a capacitor 12 arranged. The capacitor 12 The task is to cool the process air and bring it to a temperature of about 32 ° C. This distillate is separated, which by a drain 4 discharged and about can be processed into drinking water. In this case, no spray system can be used, otherwise a mixing between salt water and distillate would occur.

Preferably, therefore, a metal or multiwall capacitor is used. Between saturated air and metal condenser, the heat transfer coefficient α would normally be 0.05. However, it is likely that film or droplet condensation will occur, which would increase the value of α to 3. Therefore, the transition area is only about 78 m ² .

In the condenser 12 Seawater is used as a coolant. The seawater stays inside the condenser 12 , the distillate is formed separately on the outside of the condenser and can be removed. The process water used as a coolant heats up to about 79 ° C due to the heat energy liberated during the condensation of the saturated air and becomes a heating device 18 , For example, a solar collector with optional heat exchanger, supplied to be heated to the required 86 ° C. The heated process water then becomes the sprayer 20 fed.

Furthermore, according to the invention, a process air inflow 38 in the lower part of the evaporator tank 6 provided in which an air conveyor 22 is arranged. The air conveyor 22 is preferably a fan. The amount of air from the fan 22 Transported process air can be controlled specifically. The condensation tank 2 indicates a corresponding process air outflow 36 on. In the embodiment of 1 Therefore, the air circulation of the device is designed to be open. Process air is sucked from the environment and released to the environment after passing through the device. In alternative embodiments, the air circuit can also be realized closed, wherein process air outflow 36 Process air flow 38 then connected via an air line. See for example the embodiments of the 2 - 5 , each showing exemplary closed air circuits.

Process air outflow 36 and process air inflow 38 are arranged in the lower region of the respective container. In the 1 the preferred variant is shown according to the process air drain 36 and process air inflow 38 located at the bottom of each container, which is essentially the main one Direction of the air flow corresponds. Alternative arrangements are also possible, for example laterally in the lower region of the respective container.

In interaction of fan 22 and blinds 10 Thus, it is possible, under controlled conditions, to achieve a significantly higher air throughput per unit of time, the flow preferably being substantially turbulent. As a result of the CMEH process according to the invention in the industrial water production apparatus, a multiple of seawater per unit time can be evaporated compared to conventional MEH plants, and thus a multiple of distillate can be obtained.

In 2 is a development of the embodiment of 1 shown. Here is still an air line between the upper part of Verdunsterbehälters 6 and the condensation tank 2 arranged. About 8-10% of the process air thus becomes the condensation tank 2 fed. The air volume is adjustable.

It can thereby be achieved that this portion of the process air is forcibly guided through the spray jet, which leads to a very intensive humidification of this proportion of air. Furthermore, the exit temperature of the process air is brought to a value close to the temperature of the sprayed seawater by the contact between a small proportion of the process air with the entire sprayed heated seawater and thus the entire heat energy transported. The lower the temperature difference, the higher the recoverable heat recovery.

The air circuit for the process air is executed here closed, but it can alternatively (not shown) as well as in 1 be shown open. In general, each embodiment of the invention may be implemented with open or closed process air circulation as needed.

In 3 is a development of the embodiment of 2 shown. In general, the required supply of heat energy to heat the preheated process water from the condenser to the required 86 ° C may come from any suitable sources. Industrial waste heat, geothermal energy, heat energy from combined heat and power plants or the like can be used. For cost and environmental reasons, however, solar energy is preferably used. For this purpose, the embodiment of the 3 as heating a solar collector 28 on, over a heat exchanger 30 heats the preheated process water. The heat exchanger 30 is optional here, alternatively, the water can also be heated directly in the solar collector.

Not shown is another embodiment. Since when using solar energy only during the daily hours of sunshine operation of the system is possible, in addition, a heat storage can be provided which holds enough heat energy for night hours to operate the device continuously or at least substantially longer. For this purpose, it is necessary to increase the power of the solar collector accordingly to fill the heat accumulator and at the same time to supply the device.

It should be emphasized that the heat accumulator is of course also available to ensure the operation of all other types of heat supply or to be able to make the heat more evenly. It is also possible to use and store heat energy that is available only occasionally and / or is inexpensive only at certain times.

In 4 is a development of the embodiment of 3 shown. Here is in the inlet of the sea water a cooler 32 intended. The cooler has the task to cool the process water, which comes with 32 ° C from the evaporation tank to 26 ° C and the condenser 12 supply. The cooling can be done with, for example, 18 ° C cold sea water. Alternatively, other cooling methods are conceivable, such as a cooling tower or chimney.

In the embodiment shown is also a mixing container 34 intended. The mixing container 34 allows that from the evaporation tank 6 Dissipate Brine water to fresh seawater as needed. However, it can also be removed as required via an adjustable sequence.

In 5 an exemplary pilot plant is shown, which operates on the principle of the invention. The system has an output of 13 liters of process water per hour. The gross output is 9.3 kW, the additional solar power is 0.9 kW. The area of the solar collector is 3 m ² . The temperatures and performances shown are only examples.

Claims (7)

Device for collecting industrial water from contaminated water, comprising: - a condensation tank ( 2 ) with a process water drain ( 4 ) and a process air outflow ( 36 ); - an evaporation tank ( 6 ) with a residual water drain ( 8th ) and a process air inflow ( 38 ); A separating device ( 10 ) with controllable permeability, which is a horizontal passage between condensation tank ( 2 ) and evaporation tanks ( 6 ) forms; A capacitor ( 12 ) in the condensation tank ( 2 ) and a coolant inlet ( 14 ) for contaminated water and a coolant outlet ( 16 ) having; A heating device ( 18 ) connected to the coolant outlet ( 16 ) and is arranged to heat the polluted water; - a spraying device ( 20 ) connected to the heater ( 18 ) and arranged, the heated contaminated water in the evaporation tank ( 6 ) to spray; - an adjustable air conveyor ( 22 ), which is set up process air to the evaporation tank ( 6 ); and - an adjustable air line ( 26 ), which is set up, process air in the upper region, preferably at the top of the evaporation container ( 6 ) and the upper region, preferably the top of the condensation container ( 2 ) to supply a portion of the air amount, preferably about 8-10%, mandatory by the spray of the spraying device ( 20 ) respectively; the permeability of the separator ( 10 ) at different positions in the separating device ( 10 ) is independently controllable from substantially closed to substantially fully open so that the air flow within the evaporation vessel ( 6 ) and condensation tank ( 2 ) can thereby be selectively influenced so that the air flow is substantially turbulent; and wherein the separating device ( 10 ) a Venetian blind with several horizontal slats ( 24 ), preferably each lamella ( 24 ) is individually controllable. Device according to one of the preceding claims, wherein the air conveying device ( 22 ) is a fan. Device according to one of the preceding claims, wherein the process air outlet of the condensation container ( 2 ) with the process air inflow of the evaporation tank ( 6 ), wherein preferably a closed air circuit is formed. Device according to one of the preceding claims, wherein the process air outlet and the process air inlet respectively in the lower region, preferably at the bottom of the condensation container ( 2 ) or the evaporation tank ( 6 ) are arranged. Device according to one of the preceding claims, wherein - the heating device ( 18 ) a solar collector ( 28 ), which is adapted, the contaminated water directly or via a heat exchanger ( 30 ) to heat up. Device according to one of the preceding claims, further comprising: - a cooler ( 32 ) between the residual water drain ( 8th ) and the capacitor ( 12 ) and is arranged to cool the residual water and the capacitor ( 12 ). Device according to one of the preceding claims, further comprising: - a heat accumulator, which is adapted to store heat energy and, if necessary, the heating device ( 18 ).

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