GB1568604A

GB1568604A - Portable desalinator apparatus

Info

Publication number: GB1568604A
Application number: GB1799/77A
Authority: GB
Original assignee: COCKBURN G
Current assignee: COCKBURN G
Priority date: 1978-01-16
Filing date: 1978-01-16
Publication date: 1980-06-04

Description

(54) PORTABLE DESALINATOR APPARATUS (71) We, GORDON COCKBURN, of British nationality and CARSTEN WOLTER, a citizen of the Federal Republic of Germany, of 2 Robson Court, Great Missenden, Buckinghamshire, England and Eduard-Lucas-Strasse 47a, D43 Essen 1, Germany respectively, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to a portable desalinator apparatus.

Small emergency distillation appliances are used aboard small vessels, e.g. yachts and boats, lifeboats, liferafts etc., instead of the high-capacity desalination units employed in large cargo and passenger vessels for the production of boiler feedwater and drinking water. Such high-capacity units are extremely heavy and space-consuming, and also require amounts of fuels and power which could not possibly be provided in small vessels under emergency condi tions. Furthermore, such units are designed for economic production, which involves, interalia, the treatment of the feedstock with sulphuric acid to reduce scale formation on the heat-exchanger tubes, as well as post-production treatment to replace trace elements and the small quantity of salt needed to maintain the health of the consumers; also, the heat balance must be optimized by employing reheaters and so on. Such an outlay is not possible in small vessels. Furthermore, emergency conditions call for simple and dependable production of potable water, not necessarily economic production.

West German Offenlegungsschift No.

2202070 defines requirements of a singlepurpose emergency appliance for the desalination of sea and brackish waters thus "dependable mode of operation, low weight, high product volume, perfect separation of feedstock and product, robust design, simple parts which are easy to clean; finally, the appliance must be capable of use not only for water, but also in households." To meet these requirements, it is known that an appliance may be constructed thus: a centrally arranged heating chamber is surrounded by several concentric sleeves with a space of annular configuration between. A small volume of liquid is continuously fed into the annular space and a relatively high heating temperature is applied to generate steam bubbles. The narrower such annular spaces are, the sooner they are clogged with scale and salt deposits. Also, the concentric sleeves are kept apart by spacers, which increase the tendency towards clogging and also interrupt the flow pattern of the feed liquid. A further disadvantage is the fact that the storage tank, which does have interior insulation, is supported at the bottom on the hearth; the heat transfer at this point increases the temperature of the liquid used for cooling the condensate. The feedstock, which is intended to rise, is slowed down on entering the annular space. Finally, the condensate space is also heated up. The immediate neighbourhood between heating space and distillation space in the lower section of the appliance causes re-evaporation of the distillate, particularly as the entry into the heating space is made of aluminium. In the final effect, these individual drawbacks at least contribute to slowing down the process. Also the appliance must be kept full during distillation in order to maintain a cooling effect. Finally, cleaning of the annular spaces calls for complete stripping of the appliance, and there is no possibility of heating foodstuffs or extracting the water content of foodstuffs.

Also known are solar distillation units which utilize the greenhouse effect. Nor mally, such units consist of a polyethylene bag which is inflated by mouth. Feed water is fed into the balloon so obtained. The temperature buildup caused by penetration of the sun's rays evaporates part of the feedstock and the vapours condense on ascending to contact the relatively cooler surface of the balloon, the droplets then running down into a collection trough. The disadvantages are: low production rate; usefui only when the sun is shining; great risk of puncturing the balloon, which is useless in the collapsed state; no positive separation of products from feedstock, especially in a rocking vessel: no possibility of extracting water from foodstuffs; considerable losses of product by the droplets falling from the walls of the balloon back into the feedstock; extremely difficult to clean once the walls of the balloon have clouded with scale, etc., which screens off the solar radi atoll to a greater or lesser extent as a factor of the time the balloon has been in use.

The known membrane systems e.g. reverse osmosis under pressure and ion exchange, are suitable only for brackish waters, i e. for feedstock waters with salt contents of approx. 0.50/:, as compared with the 3.5 j, mean value for sea water. Ion exchange calls for the availability of electric power, while reverse osmosis calls for pressures of about 40 to 100 atmospheres or more, which cannot be easily generated using manual pumps by possibly weakened survivors at sea. These processes cannot heat food or extract water from foodstuffs.

Slow freezing to isolate water molecules from salt is also unsuitable since this also requires extensive apparatus and electric power, as well as washing facilities to free the ice crystals from the adhering salt solution, which is highly concentrated after the separation of the ice crystals from the original feedstock. Such systems are constructed only for high product volumes, e.g.

in the order of several thousand cubic metres of potable water per day.

According to the present invention there is provided a portable desalinator apparatus comprising a chamber in which liquid can be evaporated by the application of heat and at least one condensing coil connected to the chamber to receive and to have condense therein the vapour from the chamber, Ihe condensing coil or coils being disposed around and thermally isolated from or thermally insulated from the lateral wall of the chamber The embodiment of the invention described below with reference to the accompanying drawings is intended to provide an emergency desalination appliance which can also heat food and extract water from food, the part used for water distillation and food heating being improved to elimi- nate small apertures and spaces which can easily clog, and the remaining parts being improved to reduce weight, eliminate the need for any extensive use of electric power as the main form of energy, to provide for almost complete separation of product from the feedstock after the distillation process, to permit operation of the appliance aboard vessels at sea, to make the appliance independent of the sunshine incidence, to permit the firing of a number of fuels, and to prevent any extensive re-evaporation of the product or premature condensation of the vapours before they are captured, as well as providing an apparatus which is robust, easy to clean, and which has no sensitive or wearing parts such as valves, membranes, or tubes conducting liquids with components that may cause clogging, e.g. salt, and which is entirely safe in operation and operates at or below atmospheric pressure, i.e. which has no pressurized parts. The embodiment of apparatus may be operated by children or by weakened survivors of disasters at sea, and is specifically designed for a very low heat input and a slow, steady production rate which gives the optimum efficiency point, i.e. the optimum ratio of product: fuel input.

The evaporation chamber suitably has plain, smooth walls which are easily cleaned, and a cover which is held down against a sealing gasket by a wing nut running on a thread cut in the extension of a chimney tube. The chamber cover may be surmounted by a detachable receptacle for pre-heating liquid to be distilled or heating up food using the waste heat emanating from the chimney tube end, such receptacle having a depending annular skirt having apertures to permit the escape of the waste gases. The evaporation chamber floor is suitably a frustro conical wall forming the upper wall of a hearth. This shape increases the chamber floor area as compared with a flat bottom and so increases the heating surface while at the same time providing a natural guide for the heat into the chimney tube for further heating effect above and below the water level in the chamber. The top end of the evaporation chamber is preferably inclined to provide a high point for vapour collection by the condensing coil.

Thus, the top can be flat instead of having the convolution found on conventional distilling apparatus used in laboratories and in older alcohol distilling plants. Accordingly, the cover may be removed easily, without the condensing coil, and can be easily cleaned. Both the evaporating cham ber and the cover can be provided with thermal insulating jackets. The hearth area can also be thermally insulated. Heat losses are thus minimized and the condensation coil cannot be heated up to the re-evaporation point.

The preferred embodiment can distil liquids while using the waste heat for preheating more liquid or for heating up foodstuffs. It thus makes efficient use of fuel.

The assembly of the vaporation chamber and the coil(s) is preferably suspended from above its centre of gravity by means of a universal-joint arrangement to stabilize the assembly when used on an unsteady surface, such as on a boat.

The preferred embodiment has a further feature for improved cooling of the vapours in the condensation coil(s) while at the same time making better use of the fuel input in that the or each condensation coil is partly enclosed or surounded by a channel which may be filled with liquid. The coil(s) runs partly through such liquid and heat is transferred from the coil(s) to the liquid, which is effectively preheated while cooling the coil(s). Cooling of the coil(s) generates a pressure therein slightly below that of the evaporation chamber so the vapour may be positively extracted by the slight suction effect so generated; this also reduces the risk of premature condensation inside the main chamber.

The preferred embodiment has the chan- nel near the bottom of the condensation coil, but it may be positioned at any point further up the coil provided that the centre of gravity of the unit is not thereby raised too far. The most effective point will be high on the coil, where the coil temperature is higher, but where the centre of gravity is still well below the cardanic ring support point and where the preheated feedstock may still be removed by simply tilting the appliance in its cardanic supports.

The stability of the apparatus is increased by the above mentioned universal-joint arrangement and can be further improved by the provision of a wide base containing fuels, a distillate collection tank and the like.

The hearth may be of detachable design to permit connection of the apparatus to a standard cooking appliance, e.g. to a pres sure stove or similar appliance, or to permit the attachment of a tank containing petro leum, paraffin or the like with a wick burner.

The base suitably contains a drawer with stops or depressions to locate the collection tank. A flexible tube leading from the end of the condensing coil enters through the top or the side of the base structure through an aperture with raised edges or a cork or rubber grommet to prevent the entry of liquid.

A similar plug may be employed for the point at which the flexible tube enters the collection tank itself. Thus, the evaporation chamber, condensation coil, flexible tube, and collection tank may be so connected that air leaks are precluded. A simple manually operated air evacuation pump may be connected at any point of the interconnected system, preferably to the collection tank, to create a reduced pressure which will reduce the boiling point of the liquid in the evaporating chamber and thus reduce the fuel input requirement.

The drawer in the base structure may contain such items as solid fuel blocks or tablets, one or more cylinders of commercially available fuel gas, bottles or cans of other liquid fuels such as methylated spirits, paraffin or the like, as well as matches, a mechanical lighter, salt tablets and/or trace element tablets to condition the distillate, as well as the distillate collection tank. This drawer may also contain spare parts such as flexible tubing and top cover gaskets or any other item considered necessary or desirable.

A gas burner pipe may be permanentlijr installed in the hearth, with an extension for the connection of a flexible pipe leading to a gas cylinder in the base drawer. The hearth may be detached for the connection of a pressure or wick-type burner of standard design. The hearth with gas pipe can also accept spirit burners of standard type, and may also be used simply as a combustion space for solid fuel tablets, for wood shavings, and for chopped-up rubber boots, plastics items, and other combustible materials. The apparatus can thus be extremely flexible as regards fuels.

A single chimney or several independent or inter-connected chimney tubes may be used, although a number of chimneys may encumber cleaning.

Where there is more than one chimney tube they can, if desired, merge at the upper end of the evaporating chamber.

The chimney tube or tubes may be plain i.e. smooth, or may be of flnned or ribbed design to increase the surface area available for heat transfer. The top or exit end of the chimney tube or tubes can have a hinged flap to facilitate draught control in conjunction with a perforated draught control strip of the hearth.

The invention will be further described with reference to the accompanying drawings, in which: Fig. 1 is a perspective view of a first em bodiment of the present invention, with the feed stock preheating channel shown encircling the bottom or terminal windings of the condensation coil, by way of exampie for the position of such channel; Fig. 2 is a front view of the embodiment of Fig. l; Fig. 3 is a plan view of the embodiment of Fig. 1; Fig. 4 is a vertical cross-section through the embodiment along A-B in Fig. 3; Fig. 5 is a vertical cross-section through top part of the desalinator cooker.

Fig. 6 is a plan view of the top part of Fig. 5; Fig. 7 is a perspective view of the receptacle which may be placed over the top part for heating food or preheating feedstock; Figs. 8 and 9 show the combustion chamber or hearth of the embodiment of Fig. 1 with the perforated draught control strip in the "lighting" position; Figs. 10 and 11 correspond to Figs. 8 and 9 but with the draught controller in the "burning" or "operating" position; and Figs. 12 and 13 correspond to Figs. 8 and 9 but with the draught controller in the 'off" position.

Referring to Figs. 1 and 2, the main parts of the appliance are a main chamber 1, a top cover 2, a condensation coil 5, a pre heating channel 6, the pivotable ring 16, the side supports 19a, 19b and the base box structure 20, and hearth 8. A desalinator apparatus embodying the present invention may have more than one condensation coil, although the illustrated apparatus has only one condensation coil.

The chamber 1 contains the chimney structure which comprises chimney tubes 3a (only one shown in Fig. 2) and has a frusto-conical base 3b forming the hearth top. The hearth is 8. The cylindrical chim ney tube 3a shown without fins or ribs, ex tends through the top cover 2 and has a threaded section 3c which accepts wing nut 4 to press the top cover 2 against the cham ber 1, and a gasket, not shown, may be interposed between top cover 2 and chamber 1. From the chamber wall la, the condensation coil connection 5a leads into the condensation coil proper 5, and may be a short stump permanently fixed to the chamber wall la or a removable socket. The condensation coil connection is made at the highest point of chamber 1, the upper edge of the side wall la lies in a plane extending obliquely of the axis of chamber 1. The cover 2 has a centrally raised portion of assymmetrical shape to balance the incline of the cover on the top edge of wall la. This raised portion may be replaced by a short section of pipe cut at the same angle as the top edge of the chamber to provide a horizontal seat for a retaining member for the cover. The condensation coil 5 is arranged at such a distance from chamber wall la that scarcely any heat is radiated from the wall to the inner surface of condensation coil 5.

The wall la of chamber 1 will normally have a sheath of thermal insulation material (not shown). In such case, the annular preheating channel 6 need not have the radially inner part of its wall 6a extending upwards over the length of chamber 1 and secured by spacers as shown in Fig. 4. The bottom end of the condensation coil 5, marked 7 in Fig. 2, is led through the wall 6a of the preheating/cooling channel 6.

Such channel 6 may be located at aily point on the condensation coil, but preferably below the centre of gravity. Channel 6 is filled with feedstock which is in thermal contact with the condensation coil for preheating of the feedstock while at the same time cooling the condensation coil windings at that point. The handle 6b and pouring spout 6e are provided to facilitate use.

Feedstock preheated in the channel 6 is poured into a receptacle such as a cup by tilting the unit in its supports, and then poured into the chamber 1 after simply removing the top cover 2. Connection of condensation coil 5 to the lateral wall la of chamber 1 instead of the conventional con ilection to the top cover as in a conventional still permits easy removal of the top cover at any time.

In order to facilitate cooling and thus condensation of the vapour which passes into the condensation coil or coils, the coil or coils may be at least partially surrounded by a water jacket, or at least partially covered with a wettable fabric, or ribbed or finned, or of a double wall construction providing a space therebetween for a cooling medium or may have a combination of all these features.

The hearth 8 has a top formed by the conical base of chamber 1, marked 3b in Fig. 2. The heating space (Fig. 4) is marked 3, and extends into the chimney tube 3a, (Fig. 2), hearth 8 being bounded laterally by an extension of chamber wall la. If the apparatus is used without the pivotal supporting system comprising ring 16, it may be placed with bottom 8b of the hearth on a suitable surface. The periphery 8a of the hearth has combustion air openings 8c and an aperture 10 for introduction of fuel or a spirit burner; aperture 10 also has a vital function in the distribution of combustion air uniformly around the hearth. Rotary perforated strip 11 has holes which by rotation of the strip can be partly or wholly aligned with those of the hearth for air regulation. The draught control strip 11 has a handle 12, which is used to rotate strip 11 for stochiometric adjustment of fuel/combustion air.

Gas ring 13 is arranged inside hearth 8, and has gas holes 14. The gas ring 13 is connected via a flexible tube 15 to a standard gas cylinder, not shown, with interposed pressure reducing valve, not shown: any other gas supply system with gas feed control may be employed.

As shown in Figs. 1 to 4, the appliance is equipped with a special mounting system by means of which the chamber 1 can pivot relative to its base which ensures that chamber 1 maintains an almost vertical attitude even when the vessel or other place in which it is used may move violently, e.g.

rolling, yawing, pitching, tossing of yachts at sea. In the illustrated form ring 16 which supports chamber 1 is provided with bearing pins 17a and 17b (Figs. 3 and 4) extending from the chamber 1 through the open spaces between the windings of coil 5, possibly with bends as shown at 17c. The ring 16 is pivotable about a second, perpendicular horizontal axis, relative to the base by means of pins 18a and 18b, Figs. 2 and 3, carried by the side supports 19a and 19b of the base. Any reasonable number of such rings may be used, and the optimum will probably be three to permit movement of the base in almost any direction without the chamber 1 moving excessively. More than three rings would probably increase the overall diameter of the appliance excessively. Side supports l9a and l9b are united under the appliance to form a stirrup shaped base 19. Base 19 may be a simple base, but the preferred embodiment has a box 20, as shown in Fig. 1, containing a drawer 20a which has raised sections 22 to hold in place product tank 21. Box 20 also has an airtight gland 24 through which the flexible tube 23 for conveying the product from condensation coil 5 to the tank 21 is led. Tank 21 may be fitted with a simple pump for partial evacuation of the entire system with the object of reducing the boiling point of the feedstock in chamber 1.

The floor of heating space 3, that is, the inside surface of the floor of chamber 1, may be fitted with an electrical heating element or elements at 3b in Fig. 2. Any surface which contacts the liquid, and particularly the resistance heating element or elements may be covered with a suitable plastics, such as Teflon (Registered Trade Mark), to protect them from damage when the chamber 1 is cleaned by scraping out the accumulation of scale and/or salt. The leads of the heating elements can be led out of chamber 1 at the joint between wall la and the top cover 2, and taken across to a suitable point on one of the side supports 19a or 19b, see Fig. 1. Thus, the embodiment may also be operated with current from available yacht batteries or the like.

Drawer 20a also accepts items such as fuel tablets, charcoal, gas cylinders, matches, spare parts such as gaskets for the ioint between wall la and top cover 2, conditioning tablets for the product water, as well as any other items thought necessary or desirable.

As shown in Figs. 5 to 7, extension 2a of heating space chimney tube 3a is taken out above top cover 2. Thus, food heating or feedstock preheating receptacle 25, can be heated by the waste heat emanating from the end of tube 3a, which has a small hinged lid (not shown) for draught regulation in conjunction with the hearth draught controller strip 11. Initially, the waste gases will accumulate in the space between receptacle wall 25a, receptacle bottom 25b, and top cover 2. After giving off heat to receptacle 25, they will pass out through holes 25c. Receptacle 25 has a wall 25a shaped to suit the configuration of top cover 2 (see Figs. 5, 6 and 7). Receptacle 25 has a handle 25d.

The top cover 2 has a raised portion to provide a flat surface for the hold-down wing nut, but this raised portion may be replaced by a simple piece of tube with the edge contacting the cover cut off at the corresponding angle.

When not operating with the installed gas ring, any suitable removable heat source can be used; any suitable fuel can be introduced through aperture 10 into space 8, and strip 11 brought into a position suitable for firing the fuel. The draught control strip 11 is then turned using handle 12 to the position shown in Figs. 8 and 9. No combustion air can flow radially through holes 8c in periphery 8a to disturb initial firing, since strip 11 has equally spaced holes 1 la which now do not correspond with openings 8c. Combustion air which does not disturb initial firing may flow through holes 1 lib of the strip and 8d of the firing space, since they do correspond in this position.

Once the fire is going, the handle 12 is brought into position as shown in Figs. 10/ 11 and the air holes are reduced in size, and in the position shown all holes llc and 8c are equally aligned. Combustion air now flows radially and reasonably uniformly around the periphery of the hearth since the larger apertures 1 lb and 8d compensate for the "missing holes" on that side.

The handle 12 can be so positioned that the combustion air can be stoichiometrically regulated to gas feed/fuel combustion.

Accordingly, the air control system permits optimum utilization of the fuel available.

Handle 12 is positioned as shown in Figs.

12 and 13 to close all the air holes for putting the fire out.

Preferably the hearth or firing chamber has a finned or ribbed upper wall. Preferably the chamber and the hearth or firing chamber are insulated from the exterior and/or from the condensing coil or coils.

The entire appliance may be stored in a package of foamed plastics, e.g. polyurethane, foamed polystyrene, and covered with a skin of plastics to provide water tightness; the package will then float in the event of falling into the sea, for example, and can be retrieved. The colour should be signal red, orange, or yellow, and the package may have a lamp which lights up when contacted by water.

Finally it may be mentioned that the appliance uses the known and dependable physical process of evaporation and condensation: the sea water/food is heated in the chamber 1 by a fire in the firing chamber 8, and the water vapours rise to enter the condensation coil or coils 5 encircling chamber 1. The resulting potable water runs down coil or coils 5 to enter the product tank 21. Conditioning may be effected using tablets or by adding a minor volume of sea water to the product.

WHAT WE CLAIM IS: - 1. A portable desalinator apparatus comprising a chamber in which liquid can be evaporated by the application of heat and at least one condensing coil connected to the chamber to receive and to have condense therein the vapour from the chambers the condensing coil or coils being disposed around and thermally isolated from or thermallv insulated from the lateral wall of the chamber.

2. Apparatus according to claim 1 wherein the longitudinal axis of the chamber is vertically disposed and the or each condensing coil communicates with the chamber through the lateral wall of the chamber.

3. Apparatus according to claim 1 or 2 wherein a heating space is disposed below the chamber, the heating space having at least one chimney extending upwardly therefrom through the chamber.

4. Apparatus according to claim 3 wherein there are a plurality of chimneys which merge with one another towards the top of the chamber.

5. Apparatus according to any one of claims 1 to 4 wherein the upper end of the chamber comprises a removable cover and is shaped to provide a base on which a container can be stood to be heated.

6. Apparatus according to claim 5 and comprising such a container, the container having a depending skirt having apertures therein for the escape of hot gas from a chimney or chimneys.

7. Apparatus according to any one of the preceding claims wherein the top edge of the lateral wall of the chamber extends obliquely to the axis thereof.

8. Apparatus according to claim 6 and 7 wherein the top cover has a centrally raised portion of assymmetrical shape to balance .he incline of the cover on the top edge.

9. Apparatus according to any one of the preceding claims having a receptacle to contain liquid which, in use, is in thermal contact with the condensation coil or coils.

10. Apparatus according to claim 9 wherein the receptacle is in the form of an annular trough around the chamber.

11. Apparatus according to any one of the preceding claims wherein the chamber and coil(s) form a unit which is pivoted, at a point above its centre of gravity, to at least one support member.

12. Apparatus according to claim 11 wherein the unit is pivoted in a manner to enable pivoting motions about two axes which are at an angle to one another.

13. Apparatus according to claim 11 or 12 wherein the support member or members is or are connected to a base for the unit.

14. Apparatus according to Claim 13 wherein the base has a drawer.

15. Apparatus according to claim 14 wherein the drawer has stops or depressions to locate a condensate-receiving container.

16. Apparatus according to Claim 14 or 15 wherein the base has an aperture with a watertight grommet to conduct a flexible tube to the interior of the base.

17. Apparatus according to any one of the preceding claims and comprising a tank for receiving condensate from the coil or coils and connected thereto by a flexible tube.

I8. Apparatus according to any one of the preceding claims wherein the underside of the chamber is formed as a hearth or firing chamber having a lateral opening for the introduction of fuel or a burner.

19. Apparatus according to Claim 18 wherein the hearth or firing chamber is fitted with a gas ring.

20. Apparatus according to Claim 18 or 19 wherein the hearth or firing cham

Claims

**WARNING** start of CLMS field may overlap end of DESC **. and can be retrieved. The colour should be signal red, orange, or yellow, and the package may have a lamp which lights up when contacted by water. Finally it may be mentioned that the appliance uses the known and dependable physical process of evaporation and condensation: the sea water/food is heated in the chamber 1 by a fire in the firing chamber 8, and the water vapours rise to enter the condensation coil or coils 5 encircling chamber 1. The resulting potable water runs down coil or coils 5 to enter the product tank 21. Conditioning may be effected using tablets or by adding a minor volume of sea water to the product. WHAT WE CLAIM IS: -

1. A portable desalinator apparatus comprising a chamber in which liquid can be evaporated by the application of heat and at least one condensing coil connected to the chamber to receive and to have condense therein the vapour from the chambers the condensing coil or coils being disposed around and thermally isolated from or thermallv insulated from the lateral wall of the chamber.

14. Apparatus according to Claim 13 wherein the base has a drawer.

20. Apparatus according to Claim 18 or 19 wherein the hearth or firing chamber has combustion air openings distributed round its periphery and an annular rotatable strip with corresponding openings registerable with said hearth or firing chamber openings to control the flow of combustion air.

21. Apparatus according to Claim 20 wherein the strip and the hearth or firing chamber each have several small openings of corresponding size distributed around their peripheries and each have a larger corresponding opening to facilitate access to the interior thereof.

22. Apparatus according to any one of Claims 18 to 21 wherein the hearth ot firing chamber has a frustro-conical upper wall.

23. Apparatus according to any one of Claims 18 to 22 wherein the hearth or firing chamber has a finned or ribbed upper wall.

24. Apparatus according to any one of claims 18 to 23 wherein the chamber and the hearth or firing chamber are insulated from the exterior and/or from the condensing coil or coils.

25. Apparatus according to any one of

Claims 18 to 24 wherein the hearth or firing chamber is provided with a removable heat source.

26. Apparatus according to any one of the preceding claims and including one or more electrical heating elements for heating liquid in the chamber.

27. Apparatus according to any one of the preceding claims and having a plastics coating on the liquid-contacting surfaces thereof.

28. Apparatus according to any one of the preceding claims wherein the condensing coil or coils is or are at least partially surrounded by a water jacket.

29. Apparatus according to any one of the preceding claims wherein the condensing coil or coils is or are at least partially covered with a wettable fabric to facilitate cooling thereof.

30. Apparatus according to any one of the preceding claims wherein the condensing coil or coils is or are of a double wall construction providing a space therebetween for a cooling medium.

31. Apparatus according to any one of the preceding claims wherein the coil or coils is or are ribbed or finned.

32. A portable desalinator apparatus coll- structed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

33. A combination comprising apparatus according to any one of the preceding claims and a watertight casing of buoyant material therefor.

34. A combination according to Claim 33 wherein the casing is provided with a lamp which will illuminate when the casing is placed in water.