GB1599809A

GB1599809A - Water distillation plant

Info

Publication number: GB1599809A
Application number: GB15579/78A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1978-04-20
Filing date: 1978-04-20
Publication date: 1981-10-07

Description

(54) IMPROVEMENTS IN OR RELATING TO WATER DISTILLATION PLANT (71) I, FRANK ALBERT CRAW FORD, a British Subject, of 5, Littlefield Lane, Grimsby, South Hurnberside, do hereby declare the invention for which I pray that a Patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to water distillation plant.

Many countries, or areas of countries, throughout the world suffer from a shortage of usable water, particularly drinking water for humans and animals, and in many tropical, or semi-tropical countries the problem is increased by evaporation of usable water from natural springs and streams, reservoirs and the like man-made conservation means, and from irrigated cultivated land. Frequently such countries and areas of countries have access to a contaminated water source, such as the sea, inland lakes and contaminated rivers and swamps and in recent years attempts have been made to utilize such contaminated waters to produce usable water for drinking and irrigation.

Known water treatment plant for producing usable water from contaminated water, such as the sea, work on the so-called "flash" principal, and wherein a pressure difference is created across a membrane, or the so-called "boiler" principal, whereby water is boiled and the steam is condensed to constitute the usable water. Both of these prior art methods require relatively complex and specialized apparatus, the plants are expensive to set up, and as both plants require a constant and substantial power source they are expensive to run so that the cost of producing water by these methods is relatively high. A further difficulty with the known treatment plants is that such plants require a water supply with a relatively low solids content and, in the event that the plant is to utilize a contaminated water supply with a substantial solids contents, additional plant for removing the solids must be installed, again substantially increasing the capital and running costs of the plant.

The present invention seeks to provide a water distillation plant which is relatively simple in construction and which is capable of processing contaminated water irrespective of the solids contents of the water and/or is capable of reducing loss of usable water by evaporation to the atmosphere.

According to the present invention there is provided a water distillation plant comprising a flexible sheet or flexible envelope, intended to isolate an atmosphere exposed to the free surface of water to be treated from the surrounding atmosphere, a condenser, and means for ducting atmosphere from within said sheet or envelope to said condenser.

Preferably the sheet or envelope comprises a transparent plastics material.

Preferably the plant includes support means for supporting a part or parts of the sheet or envelope above the enveloped free surface of the water and, in one embodiment in accordance with the invention the support means are arranged to float on the water to be treated.

Preferably the sheet or envelope includes a peripheral skirt intended to enter the water to isolate the free surface of the water within the sheet or envelope from the free surface of the surrounding water.

In one embodiment in accordance with the invention the condenser is located above the free surface of the water so that the usable water output from the condenser can be piped, under gravity, to a location remote from the sheet or envelope.

In another embodiment in accordance with the invention the condenser is located beneath the free surface of the water, in which case the water can act as the coolant for the condenser and in which case the only power source required is a means for pumping the water from the condenser output to the desired location.

The water distillation plant is preferably intended for use in tropical or semi-tropical countries where the sun rays will pass through the sheet or envelope to warm the free surface of the liquid beneath the sheet or envelope, thus to evaporate water from said free surface for ducting to the condenser, but in countries where the normal sunlight is insufficient to generate the desired rate of evaporation. or to increase the rate of evaporation in a tropical or semitropical country, the water beneath the sheet or envelope may be heated, conveniently by burning of fuel or by directing hot industrial waste into the water beneath the sheet or envelope. It will, of course, be appreciated that such hot industrial waste if simply released into the water beneath the sheet or envelope should be of a nature which will not adversely affect the atmosphere within the envelope.

The heat content of the water beneath the sheet or envelope may be increased by reflectors mounted externally of the sheet or envelope and adapted to reflect the sun rays onto the water beneath the sheet or envelope. Further, the plant may include heat reflecting means located beneath the free surface of the water beneath the sheet or envelope and intended to concentrate the heat input to a relatively thin layer of water at the free surface, thus to increase the rate of evaporation from the free surface beneath the sheet or envelope. Such heat reflecting means may be weighed to float free within the water beneath the sheet or envelope, or anchored. to maintain said means at the desired depth beneath the free surface of the water.

In certain applications. for example where the depth of water is relatively small and thereby the temperature gradient in the water is small, the apparatus may conveniently include means for increasing the surface area of the water beneath the sheet or envelope and such means may comprise wave-making or spraying means within the sheet or envelope.

When the free surface of the contaminated water is relatively large in both dimensions a single sheet or envelope may be provided but in other circumstances, for example, where the contaminated water lies in a plurality of ponds or lagoons, a plurality of envelopes may be provided and, conveniently, connected to a single condenser or having the output of a number of condensers linked to a common usable water duct.

The invention will now be described further by way of example with reference to the accompanying drawings in which: Figure 1 shows a vertical cross section through a water treatment plant in accordance with the invention, Figure 2 shows, in perspective view, a second embodiment water treatment plant and Figure 3 shows a vertical, transverse cross section through the embodiment illustrated in Figure 2.

In the embodiment illustrated in Figure 1 an envelope 11, of hemispherical configuration, made from a flexible, transparent, sheet plastics material, has its peripheral edge 1 lea weighted by a continuous weighting means 12, the envelope 11 is held in location by guide lines 13 anchored to the bed beneath relatively shallow water 14, and the atmosphere within the envelope 11 is maintained at a pressure slightly above the surrounding atmosphere so that the envelope inflates and its weighted peripheral edge 1 la lies beneath the free surface of the water 14.

Heat reflecting means are located beneath the free surface of the water within the envelope 11 and each such reflecting means conveniently comprises a sheet 15, of metal or plastics material having good heat reflecting properties, held at a desired depth beneath the free surface of the liquid 14 by a support 16. When the reflective sheet 15 would normally sink within the water 14 the support 16 may comprise a rigid support but, when the reflective plate is of such material as would normally float within the water 14 the support may comprise a flexible support such as an anchored rope or cable. However, if the reflective sheet 15 has a density which would normally cause it to sink within water the sheet may be provided with floatation means to allow a flexible support to be utilized. The sheets 15 not only reflect heat back into the thin surface layer of water but also isolate the thin layer of water above each sheet 15 from the colder water beneath the sheets 15, thus preventing heat loss from the free surface by circulation within the water.

The plant may also include heat reflectors 17 mounted on towers 18 externally of the envelope 11, and intended to reflect the rays of the sun falling thereon onto the free surface of the water within the envelope 11.

When hot industrial waste, for example, cooling water from an industrial process, is to be utilized such waste may be released adjacent the free surface of the water within envelope 11 from a duct 19, extending beneath the skirt of the envelope 11.

In operation, and with the envelope 11 inflate , sunlight passing through the envelope 11 to fall onto the water within the envelope is concentrated at the free surface of the liquid and evaporation takes place. A pipe or coil 20 the greater part of which is below the free surface of the water in the envelope 11 and preferably at such depths below the free surface as to obtain maximum cooling of the pipe has one end open to the atmosphere with the envelope 11.

The atmosphere within the pipe, cooled by the surrounding water, causes the water vapour to condense and the condensed water is removed from the pipe 20 by a pump 20a, the outlet 20b of which constitutes the usable water output from the plant.

In practice and when the plant is being brought into use the envelope 11 may be initially inflated by an air pump and thereafter the output from the pump 20a may be controlled to maintain the atmosphere within envelope 11 at that pressure in excess of atmospheric pressure required to maintain the envelope 11 inflated.

A particu:ar advantage of this type of inflated envelope construction is that, in the event of adverse weather conditions such as high winds, the envelope can be simply deflated by allowing the atmosphere therein to escape and the envelope will then lie on the water surface to present little resistance to the wind and thereby damage to the plant is avoided.

In the embodiment illustrated in Figures 2 and 3 an envelope 21 is supported by a frame comprising roof members 22 and upright members 23. The framework 22, 23 and the membrane 21 support thereon is designed to cover an elongate surface area and thus the device may be utilized for extracting water from a contaminated river or canal.

The framework 22, 23 with the membrane 21 thereon may be anchored by guide lines 24 and the roof members 22 may be additionally supported by intermediate uprights 25.

In similar manner to the envelope lithe membrane 21 has its longitudinal peripheral edges 21a, 21b weighted so that said edges sink below the surface of the water.

The transverse edges 21c and 21d of membrane 21 may also be weighted to lie beneath the water surface but in the event that the water is to flow in the longitudinal direction of the envelope the edges 21c and 21d may simply float on the surface of the water effectively isolating the atmosphere within the membrane 21 whilst offering little obstruction to the water flow through the plant.

In like manner to the first embodiment the apparatus illustrated in Figures 2 and 3 may include heat reflecting means (15, 16) beneath the free surface of the water, with or without heat reflecting means (17) externally of the envelope 21 and intended to direct sunlight onto the free surface of the water within the envelope 21. However, and again particularly when the water may be moving through the envelope in one direction, the sheets 15 preferably extend in the direction of water flow or the plant includes one or a plurality of membranes 26, located beneath the free surface of the water and intended to isolate a thin layer of water immediately beneath the free surface to prevent turbulence in the flowing water from displacing the hot evaporating layer of water at the free surface down into the colder regions and replacing said hot surface water with colder water.

It will be appreciated that the embodiment illustrated in Figures 2 and 3 can be readily used on static or slow flowing water.

Further, the plant of Figure 1 or Figures 2 and 3 requires only such water depth as to allow peripheral edge of the envelope to sink thereinto to isolate the atmosphere within the envelope from the surrounding atmosphere and thus the plant can be used with relatively shallow water. The extraction of usable water from fast flowing rivers and streams can be readily accomplished by simply diverting part of the contaminated water to form a relatively static lagoon adjacent the main stream.

Again, as the plant is not limited to the depth of water, subject to the depth being sufficient to sink the peripheral skirt of the envelope, and the system works by evaporation from the free surface of the water within the envelope the plant can be used on water irrespective of the composition or solids content of the water and, in fact, the envelope, if made to sufficient proportions, could be used to extract water from swamp land without unduly disturbing the foliage of trees or plants free standing within the area to be covered by the envelope.

Whilst the plant is of particular advantage in extracting usable water from contaminated water the plant can be used to prevent loss by evaporation from usable water stores, such as reservoirs. In the event that the distilled water output is not required said water can be returned to the reservoir and the pump utilized merely to control the atmosphere within the envelope to prevent the internal pressure from exceeding the desired pressure.

Whilst the two described embodiments propose anchoring of the envelopes it will be appreciated that in many embodiments the envelope and its supporting apparatus may be free floating.

WHAT I CLAIM IS: 1. A water distillation plant comprising a flexible sheet or flexible envelope intended to isolate an atmosphere exposed to the free surface of water to be treated from the surrounding atmosphere, a condenser, and means for ducting atmosphere from within said sheet or envelope to said conde

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. below the free surface of the water in the envelope 11 and preferably at such depths below the free surface as to obtain maximum cooling of the pipe has one end open to the atmosphere with the envelope 11. The atmosphere within the pipe, cooled by the surrounding water, causes the water vapour to condense and the condensed water is removed from the pipe 20 by a pump 20a, the outlet 20b of which constitutes the usable water output from the plant. In practice and when the plant is being brought into use the envelope 11 may be initially inflated by an air pump and thereafter the output from the pump 20a may be controlled to maintain the atmosphere within envelope 11 at that pressure in excess of atmospheric pressure required to maintain the envelope 11 inflated. A particu:ar advantage of this type of inflated envelope construction is that, in the event of adverse weather conditions such as high winds, the envelope can be simply deflated by allowing the atmosphere therein to escape and the envelope will then lie on the water surface to present little resistance to the wind and thereby damage to the plant is avoided. In the embodiment illustrated in Figures 2 and 3 an envelope 21 is supported by a frame comprising roof members 22 and upright members 23. The framework 22, 23 and the membrane 21 support thereon is designed to cover an elongate surface area and thus the device may be utilized for extracting water from a contaminated river or canal. The framework 22, 23 with the membrane 21 thereon may be anchored by guide lines 24 and the roof members 22 may be additionally supported by intermediate uprights 25. In similar manner to the envelope lithe membrane 21 has its longitudinal peripheral edges 21a, 21b weighted so that said edges sink below the surface of the water. The transverse edges 21c and 21d of membrane 21 may also be weighted to lie beneath the water surface but in the event that the water is to flow in the longitudinal direction of the envelope the edges 21c and 21d may simply float on the surface of the water effectively isolating the atmosphere within the membrane 21 whilst offering little obstruction to the water flow through the plant. In like manner to the first embodiment the apparatus illustrated in Figures 2 and 3 may include heat reflecting means (15, 16) beneath the free surface of the water, with or without heat reflecting means (17) externally of the envelope 21 and intended to direct sunlight onto the free surface of the water within the envelope 21. However, and again particularly when the water may be moving through the envelope in one direction, the sheets 15 preferably extend in the direction of water flow or the plant includes one or a plurality of membranes 26, located beneath the free surface of the water and intended to isolate a thin layer of water immediately beneath the free surface to prevent turbulence in the flowing water from displacing the hot evaporating layer of water at the free surface down into the colder regions and replacing said hot surface water with colder water. It will be appreciated that the embodiment illustrated in Figures 2 and 3 can be readily used on static or slow flowing water. Further, the plant of Figure 1 or Figures 2 and 3 requires only such water depth as to allow peripheral edge of the envelope to sink thereinto to isolate the atmosphere within the envelope from the surrounding atmosphere and thus the plant can be used with relatively shallow water. The extraction of usable water from fast flowing rivers and streams can be readily accomplished by simply diverting part of the contaminated water to form a relatively static lagoon adjacent the main stream. Again, as the plant is not limited to the depth of water, subject to the depth being sufficient to sink the peripheral skirt of the envelope, and the system works by evaporation from the free surface of the water within the envelope the plant can be used on water irrespective of the composition or solids content of the water and, in fact, the envelope, if made to sufficient proportions, could be used to extract water from swamp land without unduly disturbing the foliage of trees or plants free standing within the area to be covered by the envelope. Whilst the plant is of particular advantage in extracting usable water from contaminated water the plant can be used to prevent loss by evaporation from usable water stores, such as reservoirs. In the event that the distilled water output is not required said water can be returned to the reservoir and the pump utilized merely to control the atmosphere within the envelope to prevent the internal pressure from exceeding the desired pressure. Whilst the two described embodiments propose anchoring of the envelopes it will be appreciated that in many embodiments the envelope and its supporting apparatus may be free floating. WHAT I CLAIM IS:

1. A water distillation plant comprising a flexible sheet or flexible envelope intended to isolate an atmosphere exposed to the free surface of water to be treated from the surrounding atmosphere, a condenser, and means for ducting atmosphere from within said sheet or envelope to said conde

nser.

2. A water treatment plant as claimed in claim 1 in which the sheet or envelope is a transparent plastics material.

3. A water treatment plant as claimed in claim 1 or 2 including support means for supporting a part or parts of said sheet or envelope above the free surface of the water and in which said support means are intended to float on the water to be treated.

4. A water treatment plant as claimed in any preceding claim in which the sheet or envelope includes a peripheral skirt intended to enter the water to isolate the free surface of water within the sheet or envelope from the free surface of the surrounding water.

5. A water treatment plant as claimed in any preceding claim in which in use, the condenser is located above the free surface of the water.

6. A water treatment plant as claimed in claim .1, -2, 3 or 4 in which in use the condenser is located beneath the free surface of the water.

7. A water treatment plant as claimed in any preceding claim including means for heating water beneath the sheet or envelope.

8. A water treatment plant as claimed in claim 7 in which said means for heating the water includes reflectors outside the sheet or envelope and intended to reflect the rays of the sun onto the free surface of the water beneath the sheet or envelope.

9. A water treatment plant as claimed in claim 7 or 8 including heat reflecting means intended to be located beneath the free surface of the water within said envelope when the plant is in use.

10. A water treatment plant as claimed in any preceding claim including means for increasing the surface area of the water within the envelope.

11. A water treatment plant as claimed in claim 10 in which said means comprise wave-making or spray-making apparatus.

12. A water treatment plant as claimed in any preceding claim including a plurality of envelopes linked by ducts to a common condenser.

13. A water treatment plant substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.