EP2117665A2

EP2117665A2 - Sea water desalination system and method for preparing drinking water

Info

Publication number: EP2117665A2
Application number: EP08708698A
Authority: EP
Inventors: Hans-Jürgen QUADBECK-SEEGER; Armin Alteheld; Klaus Hahn; Dietrich Scherzer; Christof MÖCK; Bernhard Vath
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2007-02-08
Filing date: 2008-02-05
Publication date: 2009-11-18
Also published as: WO2008095930A3; CN101674869A; US20100096250A1; WO2008095930A2

Abstract

The invention relates to a method for obtaining water for domestic use by the condensation of mist or the evaporation of water containing salt or impurities and the condensation of the evaporated water. The invention also relates to systems for carrying out said method and to the use of said systems for obtaining drinking water.

Description

Seawater desalination plant and process for the treatment of drinking water

Description:

The invention relates to processes for the production of service water by condensation of mist or by evaporation of water containing salt or impurities and condensation of the evaporated water, as well as facilities for carrying out the process and their use for the production of drinking water.

Open-cell foams based on a melamine / formaldehyde condensation product are known for various heat and sound insulation applications in buildings and vehicles, as well as insulating and shock-absorbing packaging material.

For the extraction of service water and drinking water in desert areas, dew or fog can be deposited on polypropylene meshes and collected as drops of water, especially in coastal areas. To collect sufficient amounts of water, however, large networks and a corresponding collection system are necessary.

The treatment of sea water or brackish water is either very time consuming and provides only small amounts of service water or requires complex systems with the appropriate infrastructure, such as power connections.

The object of the invention was to remedy the disadvantages mentioned and to provide a method and a system for seawater desalination, which can be used with low resources in areas without electricity.

Accordingly, a process for recovering process water by condensation of mist on the lands of an open cell foam based on an aminoplast or by evaporation of saline impurities containing water from the cells of an open-cell foam based on an aminoplast and condensation of the evaporated water was found ,

As open-cell foams are preferably elastic foams based on a melamine / formaldehyde condensation product having a specific gravity of 5 to 100 g / l, in particular from 8 to 20 g / l used.

The cell count is usually in the range of 50 to 300 cells / 25 mm. The average cell diameter is generally in the range of 80 .mu.m to 500 .mu.m, preferably in the range of 100 to 250 .mu.m. The tensile strength is preferably in the range of 100 to 150 kPa and the elongation at break in the range of 8 to 20%.

For the preparation according to EP-A 071 672 or EP-A 037 470, a highly concentrated propellant-containing solution or dispersion of a melamine-formaldehyde precondensate can be foamed and cured with hot air, water vapor or by microwave irradiation. Such foams are commercially available under the name Basotect® from BASF Aktiengesellschaft.

The molar ratio of melamine / formaldehyde is generally in the range of 1: 1 to 1: 5. For the production of particularly low-formaldehyde foams, the molar ratio in the range of 1: 1, 3 to 1: 1, 8 is selected and a sulfite group-free precondensate used, such as. B described in WO 01/94436.

In order to improve the performance properties, the foams can then be tempered and pressed. The foams can be cut to the desired shape and thickness and optionally laminated for stiffening with a Unterlegeschicht. For example, a polymer or metal foil can be applied as underlay layer.

The thickness of the open-cell foam depends on the size of the seawater desalination plant and is generally in the range of 5 to 500 mm, preferably in the range of 10 to 100 mm.

Due to the elasticity of the open-cell foam, this can be simple

Way in already prefabricated container parts are inserted. Even at low temperatures, for example below -80 ⁰ C, the foam remains elastic. Damage caused by embrittlement does not occur. It is also suitable for flexible insulation of moving pipes, for example for filling hoses.

The inventive method is particularly suitable for seawater desalination by evaporation of a brine and condensation of the evaporated water, wherein the brine is introduced into an open-cell foam based on an aminoplastic.

The brine, for example, is concentrated by the action of solar radiation with the evaporation of water. By continuously carrying out the process with subsequent flow of fresh brine, the concentrated brine is removed from the open-cell foam and can optionally be used for salt preparation.

Surprisingly, a crystallization of the salt on the webs of the open-cell foam or a crusting on the surface of the open-celled Foam not observed. Apparently, the salt is concentrated in the brine by the osmotic back pressure and flushed out of the open-cell foam by the continuously fed fresh brine.

The evaporation of water or salt solutions takes place more quickly if according to the invention an open-cell foam based on an aminoplast is used as carrier. Due to the enlarged surface of the webs of the open-cell foam, the evaporation is accelerated. As long as the foam is still soaked or rinsed with water or brine, there will be no deposition of salt on the surface of the foam. The osmotic processes in the soaked foam can continue to run off.

Preferably, the process is carried out continuously. For this purpose, the brine is continuously passed through the open-cell foam based on an aminoplast. The flow rate of the brine is adjusted according to the rate of evaporation resulting, inter alia, from the surface of the foam and the climatic conditions, such as temperature and solar radiation, and the concentrating brine is continuously flushed away. Clogging by suspended parts can be avoided by brief backwashing.

A continuous continuation of the evaporation can also be achieved by using floats. For this purpose, the open-cell foam based on an aminoplast is combined with floats, which ensure that the surface of the aminoplast foam is always clearly above the liquid surface. Suitable floats may for example be made of polystyrene particulate foams (EPS) and be connected by gluing, welding or plugging with the aminoplast foam. The construction is to be finished in such a way that the aminoplastic foam is always supplied with fresh brine via its capillary forces.

Preferably, the evaporated water is condensed in a bell-shaped or funnel-shaped shell of glass or a transparent plastic and discharged via a gutter.

The inventive method allows desalination of seawater even in areas where no power connection is available. External energy does not have to be supplied. There is no salification of the open-cell foam.

The process according to the invention can also be used for the purification of dirty water. The open-cell foam also acts as a filter for suspended solids. In the purification by distillation, it is advantageous to modify the condensation surface, so that drops run better and are collected better and scattering by drops formed is reduced. Bringing a layer of an IR absorber, z. As graphite on the open-cell foam, so the surface temperature can be increased and the evaporation rate can be increased. The surface can be completely or partially provided with a black layer. Particularly preferably, the surface of the open-cell foam is structured, for example by a wavy surface, the milling of grooves or Ausschneiten of wedge-shaped sections.

A radiation-absorbing layer may also be glued or laminated to the open-cell foam unless the pores of the open-cell foam are sealed. The adhesive used should not be too hydrophobic, so that the water absorption by the open-cell foam is not hindered.

Another process for the production of service water and drinking water is based on the condensation effect of the open-cell foam based on an aminoplast. For this purpose, the dry foam can be placed for example in desert areas, especially in coastal areas. The dew or mist occurring in particular in the evening and in the morning can be deposited on the webs of the open-cell foam and stored in the cells. From a height of about 10 cm, the condensed water exits by gravity on the underside of the foam and can be collected in a gutter and passed to barrels or tanks. The collected water is thus protected from evaporation.

Examples

For the examples an open-celled melamine / formaldehyde foam with a density of about 10 kg / m3 (Basotect® from BASF Aktiengesellschaft) was used.

Example 1: (Evaporation by enlarged surface)

In a 250 ml beaker, a water-saturated Basotect® cylinder (diameter 5.5 cm, height 10 cm) was placed. The beaker and an empty beaker of the same diameter were filled with water to a level of 75 ml. The total mass of both structures was determined. After 18 hours, the weight loss without Basotect® was 5 g. When using Basotect® to increase the surface area, a mass loss of 13 g was observed under otherwise identical conditions. Example 2:

1.5 cm of cylindrical aluminum shells were completely filled with cylinders of an open-cell MeI-amine / formaldehyde foam with a density of about 10 kg / m3 (Basotect® from BASF Aktiengesellschaft) , The surface of the foam was enlarged in one case by cutting several wedges out of the cylinder surface with a knife. In both bowls was added 15.0 g of water. After 24 h at room temperature, the loss in mass was determined. It was 10% greater than the comparative sample for the enlarged surface sample.

Example 3: (Use of heat radiation for evaporation)

In a cylinder made of Basotect® (diameter 56 mm, height 160 mm), superficially 1.71 g of graphite were incorporated. The obtained cylinder and a cylinder without graphite of the same dimensions were completely soaked in water and placed in each case in 250 ml beakers filled with 75 ml of water. At a distance of 15 cm, an IR radiator with a power of 250W was installed so that both structures were irradiated in equal parts. After a period of exposure of 4 h, the loss in mass and the surface temperature were determined. The graphite-free sample had a mass loss of 9% and a surface temperature of 51 ⁰ C. The graphite-modified sample lost 16% of the mass during irradiation and had a surface temperature of 60 ^° C.

Example 4: (water treatment / desalination)

Height rise determination saline solution:

Three dry Basotect® cylinders approximately 4 cm in diameter and 10 cm high were each placed in 250 ml beakers. The beakers were filled with 100 ml of deionized water or a 5% by mass or 10% sodium chloride solution. After 16 h, the height of rise of the liquid in the foam was determined. It was in all cases about 10mm. The height of rise is little influenced by electrolytes

Evaporation saline solution:

A Basotect® cylinder (diameter 5.5 cm, height 10 cm) was soaked in a 5% by mass solution of sodium chloride and placed in a 250 mL beaker. The vessel was filled to the 75 ml mark with the saline solution. The same procedure was followed for a second cylinder of the same size but using a saline solution with a concentration of 10 mass%. Both superstructures were spaced 40 apart with an IR emitter with a power of 250W cm irradiated for 7 h. The mass loss was 15 g for the 5% saline solution, while for the 10% saline solution, 14 g of water had evaporated. The salt concentration of the higher concentrated solution in the foam and in the beaker was determined gravimetrically after irradiation. It was 10.6% in the beaker and 10.9% in the foam. No salt deposit was observed on the surface of the foam.

Example 5 (Distillation):

Two disc-shaped samples of Basotect® were soaked in a 3% aqueous solution of sodium chloride. The mass of the impregnated specimens was 121, 7 g each. The soaked foams were each placed in a glass dish. In each case, 1.5 L of PET beverage bottles, over which the tapered bottleneck had been separated, were placed over the test specimens (tube closed on one side). One of the resulting PET casings was impregnated internally with a hydrophilic nanostructured coating that accelerates the runoff of water. As a result of the structure chosen, the liquid evaporating from the foam could condense on the surrounding PET walls. In the shell the condensate could be collected. Both bottles were irradiated in equal proportions with an IR radiator (250 W) from a distance of about 40 cm. After 1 hour irradiation, the mass loss of the impregnated foam using the unmodified PET shell was 4.6 mass%, and 3.0 g of water in the shell was collected. Using the modified PET envelope, 5.9% by mass of the water evaporated and 3.6 g of water was collected. On the unmodified PET surfaces, numerous drops were seen that had not expired, while the modified surface was optically clear.

Claims

claims

1. A process for the production of industrial water by condensation of mist on the webs of an open-cell foam based on an aminoplast o- by evaporation of salts or impurities containing water from the cells of an open-cell foam based on an aminoplast and condensation of the evaporated water.

2. The method of claim 1 for seawater desalination by evaporation of a brine and condensation of the evaporated water, characterized in that one introduces the brine in an open-cell foam based on an aminoplastic.

2. The method according to claim 1 or 2, characterized in that one passes the brine continuously over an open-cell foam based on an aminoplast.

3. The method according to any one of claims 1 to 3, characterized in that the open-cell foam has a specific gravity in the range of 5 to 100 g / l.

4. The method according to any one of claims 1 to 4, characterized in that the open-cell foam of a melamine / formaldehyde condensation product having a molar ratio of melamine / formadehyde in the range of 1: 1 and 1: 5 was prepared.

5. The method according to any one of claims 1 to 5, characterized in that the surface is completely or partially provided with a black layer.

6. The method according to any one of claims 1 to 6, characterized in that condensing the evaporated water in a bell-shaped or funnel-shaped shell made of glass or a transparent plastic and derived via a gutter.

7. Water treatment plant for carrying out a method according to any one of claims 1 to 6, comprising an open-cell foam based on an aminoplast as a water reservoir.

8. Use of an open cell foam based on an aminoplast for the production of drinking water.