The present invention relates to an apparatus for extracting water from the atmosphere. More particularly* but not exclusively, the present invention relates to an apparatus for extracting water from the atmosphere, the apparatus comprising a mixer adapted to combine a secondary mixture and a primary mixture into a rich liquor, the apparatus further comprising a boiler and distillation column adapted to receive the rich liquor and split it into the secondary mixture and primary mixture and then flow the primary mixture through an evaporator in a container, the mixer also being at feast partially arranged in the container.

Apparatus for extracting water from the atmosphere are known. Such apparatus typically comprise an evaporator coil and a condenser coil connected together in a cooling loop. A coolant, typically a fluoridated refrigerant is pumped around the loop from the condenser to the evaporator by a pump. As the coolant flows from the condenser coif to the evaporator coil It flows through an expansion valve so cooling the coolant which in turn cools the evaporator coil. The evaporator coil is arranged in a container though which air flows. Moisture in the air condenses on the cold evaporator coil and is then collected.

It is known to arrange the condenser coil in the container such that the air flows over the condenser coif after the evaporator coil. This increases the efficiency of the apparatus however the efficiency is still limited.

The present invention seeks to overcome the problems of the prior art.

Accordingly, the present invention provides an apparatus for extracting water from the atmosphere, the apparatus comprising a mixer for mixing together a primary mixture and a secondary mixture to form a rich liquor, each of the primary and secondary mixtures comprising mixtures of ammonia and water, with the ammonia mass fraction of the primary mixture being higher than the ammonia mass fraction of the secondary mixture, the mixer comprising a primary mixture input port, a secondary mixture input port and a rich liquor output port; a distillation column comprising a distillation column input port, a secondary mixture output port and a primary mixture output port; the secondary mixture output port of the distiiiation column being connected to the secondary mixture input port of the mixer by a secondary mixture line; the primary mixture output port of the distillation column being connected to the primary mixture input port of the mixer by a primary mixture line; a condenser, an expansion valve and an evaporator connected in-line in the primary mixture line from the distiiiation column to the mixer; a boiler comprising a hotter input port and a boiler output port, the boiler output port being connected to the distillation column input port by a boiier output line; the boiler input port being connected to the rich liquor output port of the mixer by a rich liquor line; a container defined by a container wail, the container comprising container input and container output ports extending thro ugh the container wall; an air inlet duct arranged within the container and connected to the container input port; an air exhaust duct arranged within the container and connected to the container output port; the inlet duct and exhaust duet connected together to form a fluid passage between the container input and output ports; a heat recovery device arranged within the container, a first portion of the heat recovery device arranged in the air inlet duct and a second portion of the heat recovery device arranged in the air exhaust duct such that air flowing along the fluid passage from the container input port to the container output port flows through the first portion and then through the second portion, the heat recovery device being adapted to transfer heat from the air inlet duct to the air exhaust duet; the evaporator being arranged in the fluid passage at a point between the first portion and the second portion of the heat recovery device; at least a portion of the mixer being arranged in the air exhaust duct at a point between the second portion of the heat recovery device and the container output port. Arranging the mixer in the container increases the efficiency of the apparatus such that more water can be extracted from the atmosphere per unit of input energy.

Preferably, the evaporator comprises an evaporator coil.

Preferably the condenser comprises a condenser coil.

Preferably the condenser comprises a condenser heat exchanger having first and second sides _, , the first side being connected in-line in the primary mixture line, the second side comprising second side input and output ports; and, a condenser coil; the condenser coil being connected to the second side input and output ports.

Preferably the condenser coil is filled with a mixture of glycol and water. Preferably the mixer comprises a mixer cavity in which the primary mixture and secondary mixture combine to form the rich liquor,

Preferably the mixer cavity is connected to the rich liquor output port by a mixer cavity output line; the mixer further comprising a rich liquor heat exchanger arranged irv-iine in the mixer cavity output line.

Preferably the rich liquor heat exchanger comprises a rich liquor heat exchange coil. Alternatively the rich liquor heat exchanger comprises a primary heat exchanger having first and second sides, the first side of the primary heat exchanger being connected in-line in the mixer cavity output line, the second side of the primary heat exchanger comprising first and second ports; the rich liquor heat exchanger further comprising a rich liquor heat exchange coil, the rich liquor heat exchange coil being connected to the first and second ports of the primary heat exchanger;

Preferably the rich liquor heat exchange coil is filled With a mixture of glycol and water.

Preferably the mixer cavity is arranged in the exhaust duct.

Preferably the mixer cavity and rich liquor heat exchanger are arranged in the exhaust duct

Alternatively the mixer cavity is arranged outside the container and at least a portion of the rich liquor heat exchanger is arranged m the exhaust duct.

Preferably the apparatus further comprises a cold air conduit arranged within the container and configures to allow the flow of cold air therethrough; at least a portion of the mixer being arranged in both the cold air conduit and the air exhaust duct.

Preferably the mixer cavity is arranged in both the cold air conduit and the air exhaust duct.

Preferably the heat recovery device comprises a heat exchanger having first and second sides, the first side being arranged in the air inlet duct and the second side being arranged in the air exhaust duct.

Alternatively the heat recovery device comprises a heat wheel. Preferably the apparatus further comprises a supplemental heater arranged to heat the contents of the boiler output line before the contents reach the distillation column,

Preferably the apparatus further comprises an ammonia dryer connected in-line in the primary mixture line between the distillation column and the condenser.

Preferably the ammonia dryer comprises an ammonia dryer cavity connected in-line in the primary mixture line; the ammonia dryer further comprising an ammonia dryer coil arranged within the ammonia dryer cavity, the ammonia dryer coil being connected in-line in the rich liquor line at a point between the boiler and the mixer.

Preferably the apparatus further comprises a secondary heat exchanger having first and second sides, the first side of the secondary heat exchanger being connected in-line in the primary mixture line at a first point in the primary mixture line between the condenser and expansion valve, the second side of the secondary beat exchanger being connected in-line at a second point in the primary mixture line between the evaporator and mixer.

Preferably the apparatus further comprises a tertiary heat exchanger having first and second sides, the first side of the tertiary heat exchanger being connected in-line in the secondary mixture line, the second side of the tertiary heat exchanger being connected in-line in the rich liquor line at a point between the mixer and the boiler.

Preferably the ammonia mass fraction of the primary mixture is greater than 0.98, preferably greater than 0,99, more preferably greater than 0.999, Preferably the ammonia mass fraction of the secondary mixture is less than 0,2, preferably less than 0 _* 15, more preferably less than 0.12.

The present invention wiil now be described by way of example only and not in any limitative sense with reference to the accompanying; drawings in which

Figure 1 shows a first embodiment of an apparatus for extracting water from the atmosphere according to the invention;

Figure 2 shows a mixer cavity of a mixer according to the invention;

Figure 3 shows a further embodiment of an apparatus according to the invention;

Figure 4 shows a further embodiment of an apparatus according to the invention;

Figure 5 shows a further embodiment of an apparatus according to the invention;

Figure 6 shoes a container of a further embodiment of an apparatus according to the invention;

Figure 7 shows the container in a configuration suitable for defrosting an evaporator coil;

Figure 8 shows a further embodiment of an apparatus according to the invention;

Figure 9 shows a further embodiment of an apparatus according to the invention; and, Figure 10 shows the container of a further embodiment of an apparatus according to the invention.

Shown in figure 1 is an apparatus 1 for extracting water from the atmosphere according to the invention. The apparatus comprises a mixer 2 adapted to mix together a primary mixture and a secondary mixture to form a rich liquor. Each of the primary and secondary mixtures is a mixture of ammonia and water with the primary mixture having a higher ammonia mass fraction than the secondary mixture. The mixer 2 comprises a primary mixture input port 3, a secondary mixture input port 4 and a rich liquor output port 5,

The apparatus 1 f urther comprises a distillation column 6 adapted to split a rich liquor into a primary mixture and a secondary mixture. The distillation column comprises a distillation column input port 7, a secondary mixture output port s and a primary mixture output port 9,

The secondary mixture output port 8 of the distillation column 6 is connected to the secondary mixture input port 4 of the mixer 2 by a secondary mixture line 10. Connected between the primary mixture output port 9 of the distillation column & and the primary mixture input port 3 of the mixer 2 is a primary mixture line 11. Connected in line in the primary mixture line 11 are a condenser 12 {which in this embodiment is a condenser coil), an expansion valve 13 and an evaporator 14 (which in this embodiment is an evaporator coil). By saying a component is connected 'in line' in a line what is meant is that as a mixture flows along the fine it flows through the component before continuing along the tine. In this case the condenser 12, expansion valve 13 and evaporator 14 are arranged such that as a primary mixture flows along the primary mixture line 11 from the distillation column 6 to the mixer 2 It flows through the condenser 12, then through the expansion valve 13 and then through the evaporator 14 before reaching the mixer 2,

The apparatus 1 further comprises a boiler 15 comprising a boiler input port 16 and a boiler output port 17. The boiler output port 17 is connected to the distillation column input port 7 by a boiler output line 18. Connected between the rich liquor output port 5 of the mixer 2 and the boiler input port 16 is a rich liquor line 19, The apparatus 1 further comprises a container 20 defined by a container wall 21. Extending through the container wall 21 are container input and output ports 22,23, Connected to the container input port 22 within the container 20 is an air inlet duct 24. Connected to the container output port 23 within the container 20 is an air exhaust duct 25. The air inlet duct 24 and air exhaust duet 25 are connected together to form a fluid passage 26.

Also arranged in the container 20 is a heat recovery device 27, which In this embodiment is a heat wheel 27. The heat wheel 27 comprises a first portioh in the air inlet duct 24 and a second portion in the air exhaust duct 25. In use the heat wheel 27 slowly rotates interchanging the position of the first portion and second portion so transferring heat from the air inlet duct 24 to the air exhaust duct 25 as described in more detail below.

The evaporator coll 14 is arranged in the fluid passage 26 in the container 20 at a point between the first portion and second portion of the heat recovery wheel 27. The mixer 2 is arranged in the air exhaust duct 25 at a point between the second portion of the heat wheel 27 and the container output port 23, in use the boiler 1.5 is filled with a mixture of water and ammonia. The boiler 15 is then heated. Heating can occur in a number of different ways, for example by flowing a hot fluid over the exterior of the boiler 15, The hot fluid could for example be a hot waste oil or waste hot gas from other machinery.

Heating of the boiler 15 causes its contents to boil. A rich liquor fraction of the contents of the boiler 15 flows along the boiler output line 18 to the fractional distillation column 6. The fractional distillation column 6 splits the rich liquor into a secondary mixture and a primary mixture which exit the distillation column 6 through secondary mixture and primary mixture output ports 8,9 respectively. As described above, the primary and secondary mixtures are each mixtures of ammonia and water, with the primary mixture comprising a higher ammonia mass fraction than the secondary mixture. Preferably the primary mixture is mainly ammonia with a small amount of water _* Preferably, the primary mixture has an ammonia mass fraction greater than 0.98, more preferably greater than 0.99, more preferably greater than 0.999. Preferably the secondary mixture comprises an ammonia mass fraction less than 0.2, more preferably less than 0.15, more preferably less than 0.12.

The secondary mixture flows along the secondary mixture line 10 to the secondary mixture input port 4 of the mixer 2.

The primary mixture flows along the primary mixture line 11 to the primary mixture input port 3 of the mixer 2. As the primary mixture flows along the primary mixture line 11 it flows through the condenser coil 12. A fan 28 blows cold air over the condenser coil 12 so cooling the primary mixture and causing it to condense into a liquid. The primary mixture then flows through the expansion valve 13 where it expands and cools before flowing through the evaporator coil 14, so cooling the evaporator coil 14 before flowing to the mixer 2.

The mixer 2 combines the secondary mixture and primary mixture back together to re-form the rich liquor. This is a strongly exothermic reaction. The rich liquor exits the mixer 2 by the rich liquor output port 5, is pumped along the rich liquor line 19 by a pump 58 and back to the boiler 15.

As the same time as the above, air flows through the container 20. The air enters the container 20 via the container air input port 22 and flows along the fluid passage 26 to the container output port 23. As the air flows along the fluid passage 26 it passes through the first portion of the heat wheel 27 where it is cooled. It then flows over the cold evaporator coil 14 where it is cooled further. This causes water to condense on the outside of the evaporator coil 14. This water then drips from the evaporator coil 14 and is collected. After flowing over the evaporator coil 14, the cold air flows through the second portion of the heat wheel 27 and then over the mixer 2 so cooling the mixer. The heat wheel 27 slowly rotates so interchanging the positions of the first and second portions of the heat wheel 27. This results in the heat wheel 27 transferring heat from the inlet duct 24 to the exhaust duct 25 (or in other words transferring cold from the exhaust duct 25 to the inlet duct 24), bypassing the evaporator coil 14.

Cooling of the mixer 2 in the exhaust duct 25 significantly increases the efficiency of the mixing process allowing the apparatus 1 to maintain the same refrigeration capacitY with less primary and secondary mixture flow rate and so lower power consumption.

The mixer 2 of the embodiment of figure 1 comprises a mixer cavity 29 in which the primary mixture and secondary mixture combine to form the rich liquor. The mixer cavity 29 is shown in more detail in figure 2. The mixer cavity 29 is defined by a mixer cavity wall 30, Extending through the mixer cavity wall 30 are a plurality of input apertures 31 which are connected to the primary mixture input port 3. Extending through the opposite side of the mixer cavity wall 30 is an output aperture 32 which is connected to the rich liquor output port 5 by a mixer cavity output line 33, A hollow rod 34 extends into the mixer cavity 29. The end of the hoHow rod 34 in the mixer cavity 29 is closed, The opposite end outside the cavity 29 is open and is connected to the secondary mixture input port 4. The rod 34 has a number of rod apertures 35 in the wall of the rod 34.

In use the secondary mixture flows along the rod 34 and exits the rod apertures 35 as a fine mist. Simultaneously _» the primary mixture enters the cavity 29 through the input apertures 31 as a fine mist. The primary and secondary mixtures combine to form the rich liquor which flows along the mixture cavity output line 33 out of the mixer 2.

Shown in figure 3 is a further embodiment of an apparatus 1 according to the invention. This embodiment is similar to that of figure 2 except a rich liquor heat exchanger 36 (in this embodiment a rich liquor heat exchange coil) is arranged in line in the mixer cavity output line 33. The rich liquor heat exchange coif 36 is arranged in the exhaust duct 25. The mixer cavity 29 is arranged outside the container 20. In an alternative embodiment both the mixer cavity 29 and rich liquor heat exchanger 36 are arranged in the exhaust duct 25. Shown in figure 4 is a further embodiment of an apparatus 1 according to the invention. This embodiment is similar to that of figure 3 except in this embodiment the rich liquor heat exchanger 36 comprises a primary heat exchanger 37 having first and second sides 38,39. The first side 38 of the primary heat exchanger 37 is connected in line in the mixer cavity output line 33, The second side 39 of the primary heat exchanger 37 comprises first and second ports. The rich liquor heat exchanger 36 further comprises a rich liquor heat exchange eoil 40 connected to the first and second ports of the second side 39 of the primary heat exchanger 37. The rich liquor heat exchange coil 40 is filled with a mixture of water and glycol As the coil 40 is filled with a water and glycol mixture rather than rich liquor this enables more efficient cooling toy the col! 40.

Shown in figure 5 is a further embodiment of an apparatus 1 according to the invention. This embodiment is similar to that of figure 1 but includes a number of modifications to further increase the efficiency of the apparatus 1. In this embodiment the condenser 12 comprises a condenser heat exchanger 41 having first and second sides 42,43. The first side 42 of the condenser heat exchanger 41 is connected in line in the primary mixture line 11, The second side 43 of the condenser heat exchanger 41 comprises second side input and output ports. The condenser 12 further comprises a condenser coil 44 connected to the second side 43 input and output ports. The condenser coif 44 is filled with a mixture of water and glycol. As the condenser coil 44 is filled with a water and glycol mixture rather than primary mixture this enables more efficient heat exchange and condensing of the primary mixture.

Also arranged in the primary mixture line 11 is an ammonia dryer 45, The ammonia dryer 45 comprises an ammonia dryer cavity 46 arranged in line in the primary mixture line 11. Arranged In the ammonia dryer cavity 46 is an ammonia dryer coil 4? which is arranged in line in the rich liquor line 19 at a point between the mixer 2 and the boiler 15. As the primary mixture flows through the ammonia dryer cavity 46 it flows over the ammonia dryer coil 47. A portion of the water in the primary mixture condenses on the outside of the coil 47 and returns to the distillation column 6 via a return line: 48. This reduces the water content of the primary mixture. After exiting the ammonia dryer 45, the ammonia mass fraction of the primary mixture is typically at least 98%, it is advantageous that the primary mixture contains at least a small amount of water so that the primary mixture will cool the full length of the evaporator coil 14 so increasing the efficiency of the apparatus 1. A primary mixture which is substantially pure ammonia is however also possible.

The apparatus 1 further comprises a supplemental heater 49 between the boiler 15 and distillation column 6. This supplemental heater 49 can be used to increase the temperature of the rich liquor before it enters the distillation column 6. This increases the efficiency Of the apparatus 1 when used in high temperature environments.

The apparatus 1 further comprises a secondary heat exchanger 50 having first and second sides 51,52, The first side 54 of the secondary heat exchanger 50 is connected in-line in the primary mixture line 11 at a first point in the primary mixture line 11 between the condenser 12 and the expansion valve 13, The second side 52 of the secondary heat exchanger 50 is connected in line at a second point in the primary mixture line 11 between the evaporator 14 and mixer 2. Use of the secondary heat exchanger 50 enables the primary mixture to he cooled on its way to the expansion valve 13 by the primary mixture which has exited the evaporator coil 14. This further increases the efficiency of the apparatus 1.

The apparatus 1 further comprises a tertiary heat exchanger SB comprising first and second sides 54,55. The first side 54 of the tertiary heat exchanger SB is arranged in-line in the secondary mixture line 10. The second side 55 of the tertiary heat exchanger 53 is arranged in line in the rich liquor line 55 at a point between the boiler 15 and the mixer 2. Use of the tertiary heat exchanger 53 enables the secondary mixture to be cooled on its way to the mixer 2 by the rich liquor returning to the boiler 15. Again, this increases the efficiency of the apparatus 1.

The apparatus 1 is often used in sandy environments. In order to prevent sand ingress into the container 20 the container input and output ports 22,23 are typically covered with electrostatic filters and sand traps. Further, the heat wheel 27 is dimensioned to he relatively thin, of the order I ^Q O— 400 mm thick, typically around 200mm thick. Conduits extend through the heat wheel 27 from one face to the other and are dimensioned such that in use the velocity of air flow through them is high. The conduits are also typically straight. This means that the heat wheel 27 is very resistant to fouling and is self-cleaning. Further, a thin layer of dust on the heat wheel 27 does not affect its efficiency.

A further advantage of using a heat wheel 27 as a heat recovery device is if the container 20 becomes filled with ice one can simply stop the heat wheel 27. Warm air will then blow through the container 20 allowing one to defrost the evaporator coil 14 without altering the flow of primary mixture through the evaporator coil 14.

In alternative embodiments of the invention alternative forms of heat recovery device are possible. The heat recovery device could for example be a fixed pfate heat exchanger 56, A container 20 of an apparatus 1 according to the invention containing such a plate heat exchanger 56 is shown in figure 6, The plate heat exchanger 56 comprises first and second crossing paths therethrough, one of which lies in the air inlet duct 24 and the other of which lies in the air exhaust duct 26, Air which enters the container 20 flows along the first crossing path in the p!ate heat exchanger 56, through the evaporator coil 14 then along the second crossing path before flowing over the mixer 2,

The container 20 as shown in figure 6 contains a bypass port 57. When the bypass port 57 is opened air only flows through the first path in the plate heat exchanger 56. This air is therefore still warm when it arrives at the evaporator 14 and so will defrost the evaporator 14 before exiting the container 20 via the bypass port 57 as shown in figure 7.

In all the above embodiments the boiler 15 is directly heated by a hot fluid or the like. In alternative embodiments the boiler 1.5 is indirectly heated. A hot fluid is used to heat a bath of water of other- fluid. This water is then pumped in a closed loop over the boiler 15 so heating the contents of the boiler 15.

Shown in figure 8 is a further embodiment of an apparatus 1 according to the invention in schematic form. This embodiment is similar to that of figure 1 except the container 20 further comprises a cold air conduit 59 through which cold air is blown during operation. The mixer 2 is arranged in both the air exhaust duct 25 and cold air conduit 59, The mixer 2 comprises a mixer cavity 29 which is arranged in both the cold air conduit 59 and air exhaust duct 25 as shown. This arrangement essentially introduces two stage cooling of the mixer 2. The portion of the mixer 2 in the cold air conduit 59 is cooled to room temperature by the air flowing over it. The portion of the mixer 2 in the air exhaust duct 25 is then cooled further by the air flowing along the air exhaust duct 25. This two stage cooling increases the efficiency of the apparatus.

Shown in figure 9 is a further embodiment of an apparatus 1 according to the invention. This embodiment is simiiar to figure 8 except the mixer 2 further comprises a rich liquor heat exchange coil 36, The rich liquor heat exchange coil 36 is arranged in-tine in the mixer cavity output line 33. The mixer cavity 29 is arranged in both the cold air conduit 59 and the air exhaust duct 25. The rich liquor heat exchange coif 36 is arranged in the air exhaust duct 25.

Figure 10 shows the container 20 of a further embodiment of an apparatus according to the invention. In this embodiment the heat recovery device 27 is a heat exchanger 56, One side (first portion) of the heat exchanger is arranged in the air inlet duct 24. The other side (second portion) of the heat exchanger 56 is arranged in the air exhaust duct 25, The evaporator 14 is arranged in the fluid passage as shown. In use air enters the container 20 through the air input port 22. The air flows through the first portion of the heat exchanger 56 in the air inlet duct 24. it then flows over the evaporator 14 then through the second portion of the heat exchanger 56 in the air exhaust duct 25. After exiting the heat exchanger 56 the airflows over the mixer 2 and then out the container output port 23. Optionally a fan is arranged between the heat exchanger 56 and mixer 2 to control the air flow over the mixer 2.

In the above embodiments the heat wheel or heat exchanger is preferably manufactured from a hydrophobic material or has a hydrophobic coating thereon. Ty pical examples of hydrophobic coatings are PTFE and silicone plastic.