WO1999061125A1

WO1999061125A1 - Hybrid distillation method and apparatus

Info

Publication number: WO1999061125A1
Application number: PCT/AU1999/000203
Authority: WO
Inventors: Ian David Lloyd; Garth Rutherford Lloyd
Original assignee: Auspac Technology Pty. Ltd.
Priority date: 1998-05-22
Filing date: 1999-03-24
Publication date: 1999-12-02
Also published as: AUPP364198A0; TW478948B

Abstract

A hybrid distillation method and apparatus enables refrigerant pumped by one or more compressors (21) to be used to heat heating coils (3) in the boiling chamber (1) of a distillation unit, a hot water unit (28) which may also be heated by a solar panel (56); and to coil condensing coils (4) in the condensing chamber (2) of the distillation unit and to cool a refrigeration/freezer (45) and/or an air conditioner (50). Two or more units may operate simultaneously, controlled by a 'fuzzy' logic circuit, optionally programmed to give priority to the refrigerator/freezer (45).

Description

TITLE: HYBRID DISTILLATION METHOD AND APPARATUS

BACKGROUND OF THE INVENTION

1 - Field of the Invention

THIS INVENTION relates to a hybrid distillation method and apparatus therefor.

The invention is particularly suitable for, but not limited to, a method and apparatus for the provision of purified water, refrigeration and/or freezing of food and other materials, air conditioning and/or hot water. 2. Prior Art

Due to the rapid increase in the world's population, the ageing and deterioration of large cities' water supply pipes, and the environmental pollution caused by modern industries and agriculture, many developed and developing countries are facing the crisis of a shortage of fresh and clean drinking water. Confronted by the increasing production of industrial waste, and the increasing demand for clean drinking water, many public water supply utilities do not have the resources to remove bacteria, viruses, parasites, heavy metals, monomers, radiation substances and the like from tap (or potable) water. In August 1998, the tap water in Sydney, Australia, which is processed in one of the largest and most advanced filtration utilities, was found to be contaminated with Giardia lamblia and cryptosporidium. The tap water had to be boiled for more than one minute before being safe for drinking. This incident affected more than three (3) million people. Another recent sickness outbreak occurred in Milwaukee, in the state of Wisconsin, in the United States in 1993. It was due to the drinking of polluted tap water. This incident caused more than 100 people to die, and affected half the city population (eg., around 430,000 people). These types of incidents are believed to happen in every city in the world. Poisons and diseases, which spread through water, will continue to cause people many health problems in the near future. It is therefore important to purify the polluted water and supply the public with high quality drinking water. This is now a world topic and needs to be addressed immediately.

Water purification equipment needs to meet several requirements. The equipment must be durable and automatic. The equipment should also be versatile and be able to treat different types of industrial wastewater. The equipment should be inexpensive to produce and be able to provide high purity water at high efficiency. The waste(s) from the equipment should also be able to be safely discharged or be further treated in an economic way. The equipment itself should be easy to maintain and clean.

The Reverse Osmosis water filtration system is popular and easily available. It uses filters and membranes in the removal by filtration of the impurities from the polluted water. The Reverse Osmosis water filtration system requires the maintenance of a high waste water to produced water ratio, normally 3 to 1. This means that the system discharges 75% of the source water in order to recover 25% of pure water. As a result, the Reverse Osmosis water filtration system wastes a lot of valuable water. In addition, the used membranes cannot be recycled and become an environmental pollutant.

Traditional distillation equipment boils raw water at 100°C at approximately atmospheric pressure. The equipment consumes a considerable amount of energy to boil the water; and also requires a large quantity of cooling water to condense the water vapour. The cooling water traditionally is transported to a storage reservoir or tank, where, due to the high temperature of the used cooling water, algae growth is likely. In addition, the traditional 100°C distillation method cannot be used to treat flammable solvents - this is because the high flammability of the solvents can cause explosions. It has been suggested to distillate raw water under vacuum at near ambient temperatures. However, such a design requires a large amount of water to condense the water vapour and consumes a substantial amount of energy in the recovery of the cooling water.

SUMMARY OF THE INVENTION

The proposed equipment of the present invention is designed to provide one or more of the following: inexpensive, high quality, distilled drinking water; hot water, eg., for showering; household refrigeration and/or freezing of food; and/or air-conditioned for building(s).

It is a preferred object that the running cost for this hybrid equipment is dramatically lower than the running costs of existing individual appliances. It is a further preferred object that the equipment is suitable for households, schools, communities, isolated islands, factories, boats and hospitals.

It is a still further preferred object that the hybrid equipment can also be used to treat industrial wastewater, recover and recycle solvents and/or to concentrate polluted water or industrial toxic wastewater, where the distilled water recovered can be recycled, and the remaining waste can be economically removed or stored.

It is a still further preferred object that the hybrid equipment can also be used to desalinate seawater to make it drinkable, where, eg., 75 litres of the water distilled from 100 litres of seawater could be retained. The remaining, eg., 25 litres of concentrated seawater can then be used to produce salts, with economic values.

Other preferred objects will become apparent from the following description. In one aspect, the present invention resides in a hybrid distillation method wherein: a refrigeration apparatus, having at least one compressor, pumps refrigerant through at least one heating coil in a boiling chamber of a distillation apparatus, the boiling chamber being maintained at below atmospheric pressure by vacuum means to enable distillation of raw liquid at substantially ambient temperature; the raw liquid is converted to a vapour which is transferred to a condensing chamber of the distillation apparatus; and the vapour is condensed to a liquid distillate by condensing coils in the condensing chamber, the refrigerant being pumped through the condensing coils, downstream of a condensor, and returned to the compressor(s).

Preferably, a portion of the raw liquid to be distilled is drawn, from a source, through secondary condensor coils in the condensing chamber, to assist the condensing of the vapour, before being fed to the boiling chamber. Preferably, the refrigerant and the raw liquid passing through the secondary condensing coils transfer a portion of the heat from the condensing chamber to the boiling chamber to reduce the energy input required to heat the raw liquid for distillation.

Preferably, a portion of the raw liquid is circulated through a raw liquid eductor and a raw liquid tank by a raw liquid pump, the raw liquid eductor being operably connected to the boiling chamber to reduce the pressure in the boiling chamber.

Preferably, a portion of the distilled liquid is circulated through a distilled liquid eductor and a distilled liquid tank by a distilled liquid pump, the distilled liquid pump being operably connected to the condensing chamber to reduce the pressure in the condensing chamber.

Preferably, entrainment sensor means are provided in the condensing chamber to detect any contamination in the vapour entering the condensing chamber, and are operably connected to dump means to divert any contaminated distillation liquid to the raw liquid tank.

Preferably, a portion of the refrigerant, from the condensor, is diverted from the condensing coil(s) in the condensing chamber to cool the raw liquid tank and/or the distilled liquid tank.

Preferably, refrigerant flows downstream of the heating coil(s) to heat a body of water in a hot water heater, a first valve means isolating the condensor of the refrigeration apparatus until the water in the hot water heater reaches a preset level. Preferably, the water in the hot water heater is also heated by fluid circulated through at least one solar panel by a pump, optionally wind-driven.

Preferably, the refrigerant, after passing through the condensor, is optionally passed through a refrigeration and/or freezing unit and/or an air conditioning unit.

In a second aspect, the present invention resides in a hybrid distillation unit including: a distillation apparatus having a boiling chamber for the raw liquid to be distilled and a condensation chamber for the collection of the distillate from the raw liquid; vacuum means connected to the distillation apparatus to reduce the pressure in the distillation apparatus to enable distillation of the raw liquid at substantially ambient temperature; and refrigeration apparatus having at least one compressor to pump refrigerant through at least one heating coil in the boiling chamber, a condensor, and at least one condensing coil in the condensing chamber; so arranged that: under reduced pressure in the distillation apparatus, refrigerant pumped through the heating coil(s) causes the raw liquid in the boiling chamber to boil to generate vapour which is condensed by the condensing coil(s) in the condensing chamber into liquid distillate. Preferably, the distillation apparatus further includes: secondary condensing coils in the condensing chamber, so arranged that a portion of the raw liquid is passed through the secondary condensing coils to assist the condensing of the vapour to the liquid distillate before the partially heated raw liquid is fed to the boiling chamber to be distilled.

Preferably, the vacuum means includes: a raw liquid eductor operably connected to the boiling chamber to reduce the pressure therein, raw liquid being circulated through the raw liquid tank by a raw liquid pump. Preferably, the vacuum means further includes: a distillate eductor operably connected to the condensing chamber to reduce the pressure therein, distillate being circulated through the distillate eductor and a distillate tank by a distillate pump. Preferably, the refrigeration apparatus has a first valve means operable to selectively direct refrigerant, which has passed through the condensor, to the condensing coil(s) and/or to first and/or second cooling coils in the raw liquid tank and distillate tank, respectively, to cool the raw liquid and the distillate in the raw liquid tank and distillate tank.

Preferably, the distillation apparatus includes: anti-foaming and/or contamination sensors between the boiling chamber and the condensing chamber; and dump means, controllable by the sensors, to divert any contaminated liquid distillate to the raw liquid tank, to prevent contamination of the liquid distillate in the distillate tank.

Preferably, the unit further includes: a hot water heater having at least one heating coil in hot water; a body of water, the heating coil(s) being interposed between the heating coil(s) in the boiling chamber and the condensor; and second valve means operable to isolate the condensor to direct refrigerant to the hot water heating coil(s) to heat the body of water. Preferably, the unit further includes: a refrigeration and/or freezer unit; and third valve means operable to direct refrigerant, which has passed through the condensor, to the refrigerator and/or freezer unit.

Preferably, the unit further includes: an air conditioning unit; and fourth valve means operable to direct refrigerant, which has passed through the condensor, to the air conditioning unit. Preferably, the unit further includes: a solar heating panel and a pump means to circulate hot water through the hot water heater to assist the heating of the body of water. Preferably, the pump means is driven by a wind and/or convection-powered fan.

Preferably, the unit includes: liquid level sensing means in the boiling chamber operably connected to an inlet valve for the secondary condensing coil(s); and control means, connected to the sensor means, to close the inlet valve when the liquid level in the boiling chamber exceeds a preset level.

Throughout the specification, the term "refrigeration apparatus" shall include "heat pump". BRIEF DESCRIPTION OF THE DRAWINGS

To enable the invention to be fully understood, preferred embodiments will now be described with reference to the accompanying drawings, in which:

FIG. 1 is a flow chart of a first embodiment; FIG. 2(a) is a schematic drawing of a mechanical float switch used in the first embodiment;

FIG. 2(b) is a similar drawing of an electrical capacitance level switch;

FIG. 3 is a schematic drawing of a wind driven pump; FIG. 3(a) is a schematic sectional view of the pump impellor;

FIG. 4 is flow chart of a second embodiment;

FIG. 5 is a flow chart of a third embodiment; and

FIG. 6 is a flow chart of a fourth embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The flowchart of the first preferred embodiment system is shown in FIG. 1. The thick black line represents the refrigerant line. The (heat pump) system utilizes refrigerant as the medium to transfer heat from one device to another. The system can use one or several compressors for the delivery of the refrigerant to achieve high efficiency. This hybrid equipment can affect several different operations. Depending on the settings, the operations can be divided into (i) a cold distillation process, (ii) a hot water process, (iii) a refrigerator/freezer process, (iv) an air conditioning process and (v) a solar power circulation process. All of the processes can be operated simultaneously or in different combinations, based on the demand(s) on the system. This is achieved by the control of the system by Fuzzy Logic Circuits. These are schematically represented by the dashed lines. The following are the descriptions of each process, (i) Cold Distillation Process

The distillation chamber contains a boiling chamber (1 ) and a condensing chamber (2). The heating coils (3) within the boiling chamber (1 ) can be copper tubes, stainless steel tubes or "Teflon" coated copper tubes. The function of heating coils (3) is to heat up the raw water in the boiling chamber (1 ). Respective refrigerant condensing coils (4) and raw water condensing coils (5) are provided in the condensing chamber (2). These two types of tubes can be stainless steel tubes or

"Teflon" coated copper tubes. The function of the refrigerant condensing coils (4) and the raw water condensing coils (5) is to condense the water vapour in the condensing chamber (2). "Teflon" is a registered trade mark. Before the operation of the cold distillation process, the distillate tank (6) should contain distillate or clean tap water. After filling the distillate tank (6) and the raw water tank (7), the main switch can then be opened to commence distillation.

Once the main switch is on, the Fuzzy logic circuit (100) will open the solenoid valve (8), and switch on both the distillate pump (9), and the raw water pump 10.

Raw water will circulate between the raw water tank (7), an eductor (11 ) in the inlet side of the raw water pump (10) and the raw water pump (10). Due to the pressure difference generated by the eductor (11 ), the air in the boiling chamber (1 ) will flow through compensating T-piece (12), ball valve (13), check valve (14), eductor (11 ), raw water pump (10) and into raw water tank (7). The air then escapes to the atmosphere from the raw water tank (7) outlet. The pressure in the boiling chamber (1 ) is gradually decreased.

Similarly, due to the operation of the distillate pump (9), the distillate will circulate between the distillate tank (6), an eductor (15) installed in the inlet of the distillate pump (9), and the distillate pump (9).

Because of the pressure difference generated by the eductor (15), the air in the condensing chamber (2) will fiow through the conductivity detector (16), 3-way solenoid valve (17), eductor (15), distillate pump (9), and into the distillate tank (6). The air then escapes to the atmosphere through the distillate tank (6) outlet. The pressure in the condensing chamber (2) is gradually decreased.

Once the pressure in the boiling chamber (1 ) has fallen below the atmospheric pressure, raw water, from a source supply, will flow into the boiling chamber (1 ) via the electromagnetic anti-scaling tube (18), strainer (19), solenoid valve (8), and the raw water condensing coils (5). (There is a magnetic field in the electromagnetic anti-scaling tube (18) to reduce the scaling on the heating coils (3) in the boiling chamber (1 ). The strainer (19) prevents any large particles in the raw water flowing into the boiling chamber (1 ).) A portion of the raw water flowing into the boiling chamber

(1 ) will also flow through compensating T-piece (12), ball valve (13), check valve (14), eductor (11 ), and raw water pump (10), into raw water tank (7). The excess raw water in the tank is then discharged through the raw water tank (7) outlet to a source supply. By discharging some of the raw water from the boiling chamber (1 ), the total dissolved solids (TDS) concentration of the raw water in the boiling chamber (1 ) can be controlled. The opening of the ball valve (13) can be adjusted to vary the quantity of raw water being withdrawn - the higher the TDS concentration in the raw water, the bigger the opening of the ball valve (13). The opening of the ball valve (13) also controls the ratio of the produced distillate to the discharged wastewater. When the pressure in the boiling chamber (1 ) is below , eg.,

60kPa, the amount of raw water drawn into the boiling chamber (1 ) is more than the amount of raw water being discharged. The water level in the boiling chamber (1 ) starts to increase gradually. Once the raw water level in the boiling chamber (1 ) reaches a preset level in the water level sensor (20), the Fuzzy Logic Circuit (100) will close the solenoid valve

(8).

In this system, the water level sensor (20) (see FIG. 2) is outside the boiling chamber (1 ). There are two pipes connecting the boiling chamber (1 ) and condensing chamber (12) and the water level sensor (20). The water level sensor (20) includes a water container with a water level measuring device, such as a mechanical float switch (as shown in FIG. 2a) or an electrical capacitance level switch (as shown in FIG. 2b). In the situation where mechanical float switch is used, the float 58 will move up and down with the raw water level. If the float (58) reaches the top of the stem, the Fuzzy Logic Circuit (100) will close the solenoid valve (8) and stop the flow of the raw water into the boiling chamber (1 ). If an electrical capacitance level switch is used, the raw water level in boiling chamber (1 ) is determined by measuring the capacitance using capacitance-measuring device (59). The solenoid valve (8) will be closed when the measured capacitance reaches the preset value. It was found experimentally the distance between the capacitance measuring device (59) and the boiling chamber (1 ) needs to be at least several centimetres to prevent the interference from the raw water in the boiling chamber (1 ). By installing the water level sensor (20) outside the boiling chamber (1 ), the water level sensor (20) is not affected by fluctuation in the raw water level in the boiling chamber (1 ). As a result, the solenoid valve (8) will not be damaged due to fast oscillations. In addition, by changing the height of the water level sensor (20) relative to the boiling chamber (1 ), the raw water level in the boiling chamber (1 ) can be adjusted to treat different types of raw water.

Once the solenoid valve (8) is closed, it will not open again for at least a preset period of time, regardless of the raw water level in the boiling chamber (1 ). Alternatively, the time and frequency during which the raw water is drawn into the boiling chamber (1 ) can be preset and controlled by the Fuzzy Logic Circuit (100).

When the pressure in the distillation chamber reaches, eg., 95kPa, the Fuzzy Logic Circuit (100) will turn on the compressor (21 ), open both solenoid valve (22) and solenoid valve (23), and close solenoid valve (24). Refrigerant from compressor (21 ) flows through heating coils (3) in the partial vacuum in the boiling chamber (1 ), and the raw water in the boiling chamber (1 ) will boil at near ambient temperature. A large portion of the raw water is converted into water vapour. The water vapour then ascends, penetrating through the anti-entrainment mesh (25) (between the chambers (1 ) and (2)), and arrives in the condensing chamber (2). The anti-entrainment mesh (25) stops the liquid water droplets produced in the turbulence in the boiling chamber from entering the condensing chamber (2).

A pair of foaming detectors (26) are provided above the anti- entrainment mesh (25), in a U-shaped container above the boiling chamber (1 ). An AC current is applied to the foaming detectors (26). If any foam, bubbles or raw water rises and flows into the U-shaped container, there will be electrical conductivity between the foaming detectors (26) and the U-shaped container. This will trigger the Fuzzy Logic Circuit (100) to close the solenoid valve (8) for a preset period of time, regardless of the raw water level in the boiling chamber (1 ). This shuts off the flow of the raw water entering the boiling chamber (1 ), and prevents the foam, bubbles or raw water from entering the condensing chamber (2). It also prevents the raw water from overflowing in the boiling chamber (1 ) in the case of the failure of the water level sensor (20). However, if the conductivity between foaming detectors (26) and the U-shaped container continues for a preset time, the Fuzzy Logic Circuit (100) will close the solenoid valve (8) and shut off distillate pump (9), raw water pump (10), compressor (21 ), and solenoid valve (23). The cold distillation process is terminated as a safety step.

Holes in the bottom of the U-shaped container allow any raw water received therein to flow back to the boiling chamber. The use of alternating current between the detectors (26) and the container minimises oxidation and reduction reaction in the raw liquid. After passing through the foaming detectors (26), the water vapour will descend into the condensing chamber (2). When the water vapour touches the refrigerant condensing coils (4) and the raw water condensing coils (5), it condenses into distillate and falls to the bottom of the condensing chamber (2). The distillate is then drawn through the conductivity detector (16), 3-way solenoid valve (17), eductor (15), by the distillate pump (9), into the distillate tank (6). If the conductivity of the distillate drawn from the condensing chamber (2) is higher than a value preset in the Fuzzy Logic Circuit (100), the 3-way solenoid valve (17) will open and direct the contaminated distillate to check valve (14), to flow via eductor (11 ), raw water pump (10) into the raw water tank (7).

The refrigerant from the heating coils (3) flows through the condensing pressure regulator (27), hot water heater (28), solenoid valve (22), and into the condensor (29).

The function of the condensing pressure regulator (27) is to adjust the refrigerant pressure in the heating coils (3) of the boiling chamber (1 ). The fans (30) and (31 ) on the condensor (29) are controlled by the Fuzzy Logic Circuit (100). They are used to reduce the temperature of the refrigerant in the condensor (29). The residual heat in the system can therefore be released into the atmosphere. This is particularly important to enable the system to operate in high temperature environments.

Refrigerant from the condensor (29) flows through the receiver (32), dryer (33), expansion device (34), and into the refrigerant condensing coils (4). While in the refrigerant condensing coils (4), the refrigerant expands and absorbs the heat. The refrigerant then flows into check valve (35), Venturi T-piece (36), and finally returns to the compressor (21 ).

A portion of the refrigerant from the condensor (29) flows through the solenoid valve (23). A fraction of this portion then flows into expansion device (37) and cooling coils (39) in the water tank (7), while the other fraction flows into expansion device (38), and the cooling coils (40) in the distillate tank (6). The purpose of this circulation is to reduce the temperature of the distillate tank (6). The purpose of this circulation is to reduce the temperature of the raw water in the raw water tank (7) and the temperature of the distillate in the distillate tank (6). These two refrigerant streams then join and flow through check valve (35), Venturi T piece (36), and finally return to compressor (21 ).

The solenoid valve (41 ), controlled by the Fuzzy Logic Circuit (100), will open for a very short period of time at a preset time interval. While it is opened, air from atmosphere will flow through solenoid valve (41 ), compensating T-piece (12), and into the boiling chamber (1 ). Under the impact of the air, the solid deposits accumulated at the bottom of the boiling chamber (1 ) will be fractured. The fractured pieces are then drawn through compensating T piece (12), ball valve (13), check valve (14), eductor (11 ), raw water pump (10) and finally into raw water tank (7). It is then discharged from the raw water tank (7) outlet. The cold distillation process can also be used to treat industrial wastewater, sewage water, and toxic waste or to desalinize water. To prevent the dissolved solids in the raw water from scaling onto the heating coils (3) or inside the boiling chamber (1 ), it is required to add anti-scaling agents into the raw water. This also extends the lifetime of the distillation chamber. The dosing tank (44) contains anti-scaling agents, and Solenoid valve (43), controlled by the Fuzzy Logic Circuit (100), opens at preset time intervals to add the anti-scaling agent into the raw water. Depending on the type of raw water being treated, the chemical compositions of anti-scaling agents and amount of anti-scaling agents being added should be varied. Anti-foaming agents can also be added into the dosing tank (44) to prevent the foaming in the boiling chamber (1 ).

A storage tank can be connected into the outlet of the distillate tank (6) to store distillate. If the storage tank is full, the Fuzzy Logic Circuit (100) shall close the solenoid valve (8) and solenoid valve (23), and turn off the distillate pump (9), raw water pump (10), and compressor (21 ). The cold distillation process is then terminated, (ii) Hot Water Process

There is a temperature sensor (28a) installed in a hot water heater (28). When the temperature of the water in the hot water heater (28) is below a preset temperature, the Fuzzy Logic Circuit (100) will close the solenoid valve (22) and open the solenoid valve (24). The refrigerant from the compressor (21 ) flows through the heating coils (3), condensing pressure regulator (27), and into the hot water heater (28). After releasing heat into the water in the hot water heater (28), the refrigerant then flows through solenoid valve (24) and returns to compressor (21 ).

Once the temperature of the water in the hot water heater (28) reaches the preset value, the Fuzzy Logic Circuit (100) will close the solenoid valve (24) and open solenoid valve (22) and solenoid valve (23). (iii) Refrigerator/freezer process There is a temperature sensor (45a) in a refrigerator/freezer

(45). When the temperature in the refrigerator/freezer (45) is higher than a preset value, the Fuzzy Logic Circuit (100) will close both the solenoid valve (23) and solenoid valve (24), open both the solenoid valve (22) and solenoid valve (46). The refrigerant from the hot water heater (28) flows through solenoid valve (22), condensor (29), solenoid valve (46), expansion device (37), and into refrigerator/freezer (45). Inside the refrigerator/freezer (45), the refrigerant expands and absorbs heat. It then flows through sensing bulb (48), check valve (49), Venturi T-piece (36) and returns to compressor (21 ).

When the cold distillation process and the refrigerator/ freezer process operate simultaneously, one part of the refrigerant from condensor (29) flows into solenoid valve (46), expansion device (47) and into refrigerator/freezer (45) and the other part flows into receiver (32), dryer (33), expansion device (34), refrigerant condensing coils (4), and check valve (35). These two refrigerant streams join at the Venturi T- piece (36), and return to the compressor (21 ). (iv) Air Conditioning Process

There is a temperature sensor (50a) in an air conditioner (50). When the room temperature measured by the temperature sensor is higher than a preset value, the Fuzzy Logic Circuit (100) will close both the solenoid valve (23) and solenoid valve (24), open both the solenoid valve (22) and solenoid valve (51 ). The refrigerant from the hot water heater (28) flows through the solenoid valve (22), condensor (29), solenoid valve (51), expansion device (52) and into air conditioner (50). The refrigerant expands and absorbs heat in the air conditioner (50). It then flows through the sensing bulb (53), check valve (49), Venturi T piece (36) and returns to the compressor (21 ).

When the cold distillation process and air conditioning process are running simultaneously, one part of the refrigerant from the condensor (29) will flow through the solenoid valve (51 ), expansion device (52) and into air conditioner (50), while the other part will flow through receiver (32), dryer (33), expansion device (34), refrigerant condensing coils (4), and check valve (35). These two refrigerant streams eventually join at Venturi T-piece (36) and return to compressor (21 ).

(v) Solar Power Circulation Process The solar power circulation process only operates on sunny days. During the day time, the water in the solar panel (56) is heated up by the sun. A conventional fan (54) (see FIG. 3), which is installed on the roof or outdoors, is rotated by the wind. The conventional fan (54) drives a pump (55) to circulate the water. The water heated in the solar panel (56) is circulated by the pump (55) to the hot water heater (28), where it gives up heat to the water in the hot water heater (28). Therefore, the solar power absorbed by the solar panel (56) can be utilised in heating up the water in the hot water heater (28) using water as a medium.

In a second embodiment, the system can recover a high percentage of distilled water from the raw water. For the areas where the water source is limited and water is difficult to obtain, such as deserts and isolated islands, the required water purification system should be able to recover as much water as possible from the source. Similarly, to process industrial toxic waste water and environmentally polluted hospital waste water, it is preferred to recover most of the water and leave high concentrated, small quantity of waste for further processing or storage. This not only can recover and recycle the water, therefore reducing the water consumption by the factories and the hospitals, but also reduce the transportation and processing cost of the remaining waste.

This system can also be employed to concentrate industrial waste into small volume and high concentration. To process raw water with different levels of total dissolved solids concentration, the opening of the Bull valve (13) can be adjusted to vary the waste being discharged from the boiling chamber (1 ). The smaller the opening of the Ball valve (13), the higher the total dissolved solid concentration in the raw water in the boiling chamber (1 ). Although the raw water boils at lower temperature a nd under vacuum condition, the higher total dissolved solid concentration in the raw water will unavoidably produce scaling on the heating coils (3) and the solid deposits at the bottom of the boiling chamber (1 ). As a result, the boiling chamber (1 ) will need to be cleaned after a period of operation. To be able to remove easily the solid deposits at the bottom of the boiling chamber (1 ) and the scaling on the heating coils (3), the distillation chamber in FIG. 1 is modified. As shown in FIG. 4, the boiling chamber (1 ) and the condensing chamber (2) are separated. The boiling chamber (1 ) can be opened easily by sliding the chamber along the rail (62) on the frame (63). There are clamps (60) to keep the boiling chamber (1 ) locked. The rail guide (61 ) at the bottom of the boiling chamber (1 ) can be slid along the rail (62). When there are solid deposits at the bottom of the boiling chamber (1 ) and need to be cleaned, the clamps (60) can be opened and the boiling chamber (1 ) slid to the right. The bottom of the boiling chamber (1 ) nd the heating coils (3) can then be easily accessed for cleaning. There is a handle (64) at the right of the boiling chamber (1 ) to aid sliding the boiling chamber (1 ).

In the current design, a high percentage of the raw water can be evaporated and recovered. The chamber in FIG. 4 allows the easy opening and closing of the boiling chamber (1 ). The scaling on the heating coils (3) and the leftover solid deposits at the bottom of the boiling chamber (1 ) can then be easily removed.

In a third embodiment, the system can utilise one or more distillation chambers to distill raw water. By connecting several distillation chambers in series, raw water can be evaporated and condensed at different temperatures to produce more distillate. The input energy can be utilised more effectively.

As shown in FIG. 5, the raw water from the solenoid valve (8) flows in sequence into the raw water condensing coil (5) in the distillation chamber (C), the raw water condensing coils (5) in the distillation chamber (B), the raw water condensing coils (5) in the distillation chamber (A). The raw water is gradually heated up. As a result, the temperature of the raw water condensing coils (5) in the distillation chamber (A) is the hottest, followed by the raw water condensing coils (5) in the distillation chamber (B) and the raw water condensing coils (5) in the distillation chamber (C). The the raw water then enters the boiling chamber (1 ) in the distillation chamber (A). The remaining raw water which is not turned into vapour in distillation chamber (A) will flow into boiling chamber (1 ) in the distillation chamber (B) and boiling chamber (1 ) in the distillation chamber (C).

Similarly, the refrigerant from the expansion device (34) will flow through the refrigerant condensing coils (4) in the distillation chamber (C), the refrigerant condensing coils (4) in distillation chamber (B) and the refrigerant condensing coils (4) in the distillation chamber (A). Therefore, the temperature of the refrigerant condensing coils (4) in the distillation chamber (C) will be the coldest, followed by the temperature of the refrigerant condensing coils (4) in the distillation chamber (A) will be the highest. Refrigerant from the compressor (21 ) will in turn flow through the heating coils (3) in distillation chamber (A), the heating coils (3) in distillation chamber (B), and the heating coils (3) in distillation chamber (C). The refrigerant gradually releases the heat. As a result, the raw water temperature in the boiling chamber (1 ) of the distillation chamber (A) will be the highest, followed by the raw water in the boiling chamber (1 ) of the distillation chamber (B), and the raw water in the boiling chamber (1 ) of distillation chamber (C).

Consequently, there is a temperature difference between the raw water in the boiling chamber (1 ) and the refrigerant condensing coils (4) and raw water condensing coils (5) in the condensing chamber

(2) in every distillation chamber. As a result, raw water in each distillation chamber can be evaporated and condensed at different temperatures.

These distillation chambers share the same pipelines for the discharge of the low volatile gases and the produced distillate. The produced distillate from each distillation chamber all flow into the condensing chamber (2) in distillation chamber (C) and then into the conductivity detector (16), 3-way solenoid valve (17), eductor (15), distillate pump (9), and finally into distillate tank (6). The distillation chambers should be maintained at different height levels to facilitate the flow of the raw water and distillate.

FIG. 6 illustrates a fourth embodiment, where a three-stage multi-flash heat pump unit can produce nearly three times the distilled water of the single unit, utilising the same input energy (ie., the same size compressor 21 ).

The feed water is passed through several heat exchangers to preheat the feed water before it enters the distillation chamber A. The feed water passes through raw water condensing coil

(5) in the distillation chamber (C) and picks up heat. The feed water picks up heat from the heat exchange (70) in the blowdown scavenger system (71 ) and then from the heat exchanger (72) refrigeration suction line (73), in place of the cooling fans (74, 75) used in the circulating tanks (6, 7) used to cool the pumps (9, 10) that enable a good vacuum to be obtained.

The tanks (6, 7) can be cooled by bleeding off some of the refrigerant. It will be noted that in chambers (A) and (B), no coiling coils (4, 5) are provided on the vapour produced in these chambers (ie., A and B) are drawn by the lower pressure, in chambers (B) and (C), respectively, by the molecular collapse of the vapour in the reducing temperature of the vapour caused by the differential temperature of the feed water and the cooling effect caused by the giving up of heat in each chamber.

The cold distillation process of the present invention, where the raw liquid (eg., water) is boiled in high vacuum but at low temperature, uses less energy, but produces more distillate, than the conventional 100% distillation method. The method avoids the changing of filters, required with Reverse Osmosis methods, thereby avoiding the problem of blockages and the growth of viruses and bacteria. Scaling of the heating coils is also minimised.

By circulating the refrigerant through the hot water heater, heat can be transferred from the heater to the refrigerant, eg., when the heater exceeds 80-85°C, to provide heat for the refrigerant, to thereby reduce the workload on the compressor(s). The selection of the compressor(s) depends on the energy circulation requirements of the system in the intended installation and such requirements will be dependent on, eg.: (1 ) the daily quantity of distillate required;

(2) the daily quantity of hot water required;

(3) the volume/type of products to be refrigerated/cooled and the ambient conditions; (4) the volume/construction of the space(s) to be air conditioned and the ambient conditions; and

(5) the amount of solar energy available. Two or more compressors can be used in series/parallel and their operation be selectively controlled. The "Fuzzy" Logic Circuit (100) can be programmed to vary the priority given to each operation, although refrigeration/freezing is usually of highest priority.

The refrigerant condensing coils and the raw water condensing coils in the condensing chamber may be interlaced or laid one above the other. It may be preferred that the vapour contacts the raw water condensing coils first, as these will be at a higher temperature than the refrigerant condensing coils, and a higher amount of heat may be transferred to the raw water before it enters the boiling chamber.

The periodic emission of atmospheric air into the boiling chamber enable the solid deposits at the bottom of the boiling chamber to be fractioned, and then discharged via the raw water eductor and the raw tank to a collection point. This avoids the necessity for mechanical scraping and/or chemical etching (using strong acids) to remove any solid deposit build up in the boiling chamber.

By selectively directing refrigerant to the cooling coils in the distillate tank, and to the cooling coils in the raw water tank, ensures that the efficiency of the respective pumps and eductors is maintained to maintain the respective vacuum in the boiling and condensing chambers of the distillation apparatus. In addition, the likelihood of bacteria and/or virus growth in the distillate tank is minimised, should any contaminated distillate enter the tank.

Preferably, the condensor is provided with a constant speed fan and a variable speed fan - the constant speed fan (30) preferably only operates while the compressor is operating, being controlled by the "Fuzzy" Logic Circuit (100). The variable speed fan (31 ) is controlled by the high pressure controller (57), and is preferably operated when the temperature of the refrigerant exceeds a preset level - if the refrigerant temperature is too high, then the system exhausts too much heat and distillate production is reduced. The provision of the constant speed fan (30) and the variable speed fan (31 ) also reduces noise and the likelihood of compressor damage from cycling on and off.

The build-up of volatile gases in the distillation apparatus, particularly above the entrainment filter (25), is avoided by the drawing of vapour from the top of the distillation apparatus via the check valve (42) and the T-piece (12) by raw water eductor (11 ). The removal of such vapours minimises any contaminants of the distillate.

It should be emphasised that the protection afforded by the design of the entrainment well with the skirt (26a) that directs any entraining droplets rising up the wall of the vapour cylinder by the draft in the hot vapour ascending tube produced by the pressure differential of the hot vapour molecules collapsing on cooling whereby these droplets or foam, bubbles, etc., are on rising directed into the well (26b) by the skirt (26a) just above the entrainment mesh (25) to be detected by conductivity probes (26) should the entrained droplets or foam, etc., pass through the said mesh. The well has holes that enable bubbles on liquefying to return to the boiling chamber (1 ). The probes have an induce AC voltage adjustable by the use of a potentiometer allowing the said voltage to be adjusted to suit conductivity requirements, the said probes (26) are insulated from the chamber and are maintained in close proximity (1.5mm) to the bottom of the stainless steel well for sensitive and quick detection.

A low AC voltage is used so the voltage, by its alternation, does not electrolytically transfer metal by the action of electrolysis from the probes or the metallic vessel whereby the coating can effect the sensitivity of the said probes. On detection of conductivity in the primary system as described above, switching of the electronics by the sensor circuit cuts off the feed-water via the feed-water solenoid valve (8) to the boiling chamber (1 ) until no conductivity is sensed. However, should the sensing of conductivity be detected on turning on again after it has timed out, the feed water valve (8) will remain off and its reactivation cancelled each time and every time such sensing is detected for some 15 to 20 seconds until the boil is stabilized and no entrainment (foaming) is detected. The cancelling time of the solenoid switching on each time conductivity is detected also ensures the solenoid valve (8) does not oscillate between the detection of contamination thereby eliminating undue wear to the said valve.

The other protection afforded to the problem of contamination, should flooding occur, or during massive ebullition, is the secondary conductivity sensing system having probes similar to the primary ones that instructs the electronics to divert any contaminated distillate that exceeds 2 to 5 parts per million or more should it pass through the condensing chamber.

The distillate will only be directed back to the distillate tank (6) when the contamination level is, eg., below 2ppm. This may occur, eg., 4-5 seconds after conductivity in the distillate is detected. As the method does not rely on measuring conductivity in the storage tank, it is more failsafe than that method.

Any contaminated distillate is re-routed to the feed-water pumping system and its cooling tank through the 3-way diverting solenoid valve (12) that is situated in the distillation suction line between the outlet from the condensing chamber (2) and the fresh water eductor (15), pump (9) and the fresh water circulating tank (6).

Should said contamination be detected by the detection system, the distillate will now be diverted away from the distillate suction pumping system consisting of eductor, pump and circulating tank so no contamination of the said distillate tank (6) can occur. Another process to consider is the means of stopping seeding at the blow down exit whereby the atmosphere is reintroduced in very short bursts via a timed switching of a solenoid valve that on the said atmosphere entering at this point (at some velocity) into the vacuum chamber whereby this short burst (every 30 seconds for approximately one fifth of a second) cause a dislodgement of the concentrating minerals and sludge at what is called the seeding point of the crystals in the course of their formation. By doing this on a regular basis, the formation of crystals and or sludge that would eventually restrict the flow of the scavenging process that maintains by the blowdown the concentration level of the feed-water.

The constant removal of a percentage of water introduced by the feed control valve related to the de-watering process of the evaporator maintains the concentrate at a level that is not congruence to scaling of the heat exchanger and boiling chamber.

It will be readily apparent to the skilled addressee that the present invention provides a flexible system which can meet a wide range of demands, and the system can be uniquely tailored to each installation by suitable programming of the "Fuzzy" Logic controls. The reason these applications can work singularly, with each other, or all together, is owed to the balancing of the various processes by electronically controlling all said functions by the use of a programmed fuzzy logic system.

The means of determining the requirements of the various processes and the juggling (switching) by electronic means of the various valves, is done in accordance with the electronic programs requirements and that relating to the status of the particular function.

As well as monitoring, correcting and maintaining the equilibrium within the evaporation chamber, the electronics are able to detect the start of entrainment and turn off the feed-water input into the boiling chamber until the temperature of the boil increases and the equilibrium within the evaporation chamber is stable. While the feed- water is turned off under the above conditions, the unit will still produce distillate.

As previously stated, all three functions are able to work at the same time and or any two together, in unison with either one or the other or on its own, the energy being mechanically synergistic.

Various changes and modifications may be made to the embodiments described without departing from the present invention.

Claims

1. A hybrid distillation method wherein: a refrigeration apparatus, having at least one compressor, pumps refrigerant through at least one heating coil in a boiling chamber of a distillation apparatus, the boiling chamber being maintained at below atmospheric pressure by vacuum means to enable distillation of raw liquid at substantially ambient temperature; the raw liquid is converted to a vapour which is transferred to a condensing chamber of the distillation apparatus; and the vapour is condensed to a liquid distillate by condensing coils in the condensing chamber, the refrigerant being pumped through the condensing coils, downstream of a condensor, and returned to the compressor(s).

2. A method as claimed in Claim 1 wherein: a portion of the raw liquid to be distilled is drawn, from a source, through secondary condensor coils in the condensing chamber, to assist the condensing of the vapour, before being fed to the boiling chamber.

3. A method as claimed in Claim 2 wherein: the refrigerant and the raw liquid passing through the secondary condensing coils transfers a portion of the heat from the condensing chamber to the boiling chamber to reduce the energy input required to heat the raw liquid for distillation.

4. A method as claimed in Claim 3 wherein: preferably, a portion of aw liquid is circulated through a raw liquid eductor and a raw water tank by a raw liquid pump, the raw liquid eductor being operably connected to the boiling chamber to reduce the pressure in the boiling chamber.

5. A method as claimed in Claim 3 or Claim 4 wherein: a portion of the distilled liquid is circulated through a distilled liquid eductor and a distilled liquid tank by a distilled liquid pawn, the distilled liquid pump being operably connected to the condensing chamber to reduce the pressure in the condensing chamber.

6. A method as claimed in any one of Claims 1 to 5 wherein: entrainment sensor means are provided in the condensing chamber to detect any contamination in the vapour entering the condensing chamber and are operably connected to dump means to divert any contaminated distillation liquid to the raw liquid tank.

7. A method as claimed in Claim 4 or Claim 5 wherein: a portion of the refrigerant, from the condensor, is diverted from the condensing coil(s) in the condensing chamber to cool the raw liquid tank and/or the distilled liquid tank.

8. A method as claimed in any one of Claims 1 to 7 wherein: refrigerant flows downstream of the heating coil(s) to heat the body of water in a hot water heater, a first valve means isolating the condensor of the refrigeration apparatus until the water in the hot water heater reaches a preset level.

9. A method as claimed in Claim 8 wherein: the body of water in the hot water heater is also heated by fluid circulated through at least one solar panel by a pump, optionally wind-driven.

10. A method as claimed in any one of Claims 1 to 9 wherein: the refrigerant, after passing through the condensor, is optionally passed through a refrigeration and/or freezing unit and/or an air conditioning unit.

11. A hybrid distillation unit including: a distillation apparatus having a boiling chamber for the raw liquid to be distilled and a condensation chamber for the collection of the distillate from the raw liquid; vacuum means connected to the distillation apparatus to reduce the pressure in the distillation apparatus to enable distillation of the raw liquid at substantially ambient temperature; and refrigeration apparatus having at least one compressor to pump refrigerant through at least one heating coil in the boiling chamber, a condensor, and at least one condensing coil in the condensing chamber; so arranged that: under reduced pressure in the distillation apparatus, refrigerant pumped through the heating coil(s) causes the raw liquid in the 5 boiling chamber to boil to generate vapour which is condensed by the condensing coil(s) in the condensing chamber into liquid distillate.

12. A unit as claimed in Claim 11 wherein: the distillation apparatus further includes: secondary condensing coils in the condensing chamber so 0 arranged that a portion of the raw liquid is passed through the secondary condensing coils to assist the condensing of the vapour to the liquid distillate before the partially heated raw liquid is fed and the boiling chamber to be distilled.

13. A unit as claimed in Claim 11 or Claim 12 wherein: 5 the vacuum means includes: a raw liquid eductor operably connected to the boiling chamber to reduce the pressure therein, raw liquid being circulated through the raw liquid tank by a raw liquid pump.

14. A unit as claimed in Claim 13 wherein: o the vacuum means further includes: a distillate eductor operably connected to the condensing chamber to reduce the pressure therein, distillate being circulated through the distillate eductor and a distillate tank by a distillate pump.

15. A unit as claimed in any one of Claims 11 to 14 wherein: 5 apparatus has a first valve means operable to selectively direct refrigerant which has passed through the condensor to the condensing coil(s) and/or to first and/or second cooling coils in the raw liquid tank and distillate tank, respectively, to cool the raw liquid and the distillate in the raw liquid tank and distillate tank. 0

16. A unit as claimed in any one of Claims 13 to 15 wherein: the distillation apparatus further includes: anti-foaming and/or contamination sensors between the boiling chamber and the condensing chamber; and dump means, controllable by the sensors, to divert any contaminated liquid distillate to the raw liquid tank, to prevent any contamination of the liquid distillate in the distillate tank.

17. A unit as claimed in any one of Claims 11 to 16, further including: a hot water heater having at least one heating coil in hot water; a body of water, the heating coil(s) being interposed between the heating coil(s) in the boiling chamber and the condensor; and second valve means operable to isolate the condensor to direct refrigerant to the hot water heating coil(s) to heat the body of water.

18. A unit as claimed in any one of Claims 11 to 17, further including: a refrigeration and/or freezer unit; and a third valve means operable to direct refrigerant, which has passed through the condensor, to the refrigeration and/or freezer unit.

19. A unit as claimed in any one of Claims 11 to 18, further including: an air conditioning unit; and fourth valve means operable to direct refrigerant which has passed through the condensor, to the air conditioning unit.

20. A unit as claimed in Claim 17, further including: a solar heating panel and a pump means to circulate hot water through the hot water heater to assist the heating of the body of water.

21. A unit as claimed in Claim 20 wherein: the pump means is driven by a wind-operated fan.

22. A unit as claimed in any one of Claims 11 to 21 , further including: liquid level sensing means in the boiling chamber operably connected to an inlet valve for the secondary condensing coil(s); and control means, connected to the sensor means, to close the inlet valve when the liquid level in the boiling chamber exceeds a preset level.