WO2006123258A2

WO2006123258A2 - Water purification and treatment device and method for desalting or purifying water

Info

Publication number: WO2006123258A2
Application number: PCT/IB2006/002061
Authority: WO
Inventors: Gerard Aknine; Jan Henrik Jebsen
Original assignee: Aquamatters Sa
Priority date: 2005-05-17
Filing date: 2006-05-17
Publication date: 2006-11-23
Also published as: WO2006123258A3

Abstract

The invention relates to water treatment devices and methods employing high temperature plasma. In a preferred embodiment, the device or method can be used in combination with a mobile water purification, distillation, or desalination system. In other embodiments, the device or method can be used to effectively and quickly heat water for use in circulating water systems, such as, for example, building heating systems. The use of plasma technology to treat or heat water provides numerous advantages, including fast and effective steam generation, a small size compatible with mobile systems, and/or cost-effective or efficient generation of steam or heated water.

Description

WATER PURIFICATION AND TREATMENT

DEVICE AND METHOD FOR DESALTING OR

PURIFYING WATER

FIELD OF INVENTION

[0001] The invention relates to water treatment devices and methods employing high temperature plasma. In a preferred embodiment, the device or method can be used in combination with a mobile water purification, distillation, or desalination system. In other embodiments, the device or method can be used to effectively and quickly heat water for use in circulating water systems, such as, for example, building heating systems. The use of plasma technology to treat or heat water provides numerous advantages, including fast and effective steam generation, a small size compatible with mobile systems, and/or cost-effective or efficient generation of steam or heated water.

BACKGROUND OF INVENTION

[0002] There are a variety of designs for desalination systems and water purification methods. In one design, the multi-stage flash distillation (MSF), a desalination plant boils water to create water vapor, then condenses the water from the vapor, and collects it as purified water. The process is energy intensive, involving both heating and cooling and typically multiple rounds of heating and cooling are required, as the name suggests. Furthermore, the multiple heating and cooling steps generally occur in separate chambers, which requires a large apparatus or system. Other techniques for desalting brackish water or seawater include electrodialysis, reverse osmosis (RO), and vapor compression. Each of these techniques requires intensive investments in capital and energy. Capital costs for these techniques are high even for brackish water because of the high pressure (1000 psi) for RO, or high temperature and moderate pressure (266 °F or 130 ⁰C and 40 psi) for MSF and vapor compression. Because water purification and desalination constitute areas of preventative defense and environmental security, there is a need for improved devices and methods not only to meet future global water demands but also for humanitarian assistance in water-starved regions and during emergency scenarios. BRIEF DESCRIPTION OF THE FIGURE

[0003] In Figure 1, an exemplary device and method incorporating the invention is depicted.

The plasma torch (torche plasma) is produced in the cylindrical chamber from the compressed air (air comprimed) and energy from source (reactor plasma 1.7 KW).

An optional embodiment includes an ultrasound generator (US) to facilitate break-up of carbon build up. Cold seawater from environment and/or hot seawater used during condensation of steam is added to chamber by pumps controlled, typically, in response to water level in chamber. Water vapor generated follows the arrows up to an optional turbine (T) connected to transformer (Tr) used to generate energy, and send the vapor into condenser coil, where water cooled and pumped out as potable water. An exhaust vent (over vapor) prevents pressure build-up in chamber during plasma torch burns. Solid bodies are allowed to sink and can be removed by pump at bottom area of chamber (gravity recuperation). An electrostatic filter (E) can be used in the flow of water vapor to provide additional purification, and other inlet and outlet filer systems, as known in the art, can be incorporated.

[0004] Figure 1 is a schematic representation of a plasma desalting machine. The machine comprises several pumps 1 to 5. Pump 1 allows the cold seawater to enter into the chamber (1), as shown in (6). The chamber (1) comprises one or more torch plasma generators (2) or power supplies (3). The chamber (1) of the machine is connected to a steam output port (4), which is itself connected to a water condensing chamber (5). The condensed liquid water may be released by pump 3 to the chamber (1) for a subsequent round of steam generation. Precipitated or solid material in the chamber (1) may be flushed using the outlet (8). A safety valve (9) is positioned at the top of the chamber (1) Pump 4 at the end of the condensing chamber (5) releases drinkable water as shown in (7). Also, fluxometer (Φ) and ultrasons (US) may be placed at the outlet (4) in case of water with carbonates.

SUMMARY OF THE INVENTION

[0005] The invention, in one aspect, encompasses the use of a plasma torch or high temperature plasma generator in combination with a water treatment system, a water distillation and/or desalination system, or a steam generation system, as well as methods for using these systems. In an exemplary distillation and/or desalination system of the invention in which one or more plasma torches is used to produce steam from water, the system is effective in purifying against microorganisms, sediment, particulate matter, and heavy metals. In optional methods and systems of the invention, the distillation system can be combined with a carbon filter step, especially when organic chemical contamination is suspected. The carbon filtration can occur in the steam or liquid state, and thus can be used in one or more places in a treatment system or method.

[0006] In one aspect of the invention, a method is provided using one or more plasma generators within a chamber that is capable of being at least partially filled with water. A power supply and air or gas supply to the one or more plasma generators is used to generate one or more plasma torches or flames. When the one or more high temperature plasma torches or flames are positioned at the surface of or under the surface of the water level in the chamber, or in contact with the water in the chamber, steam is quickly produced. The steam is collected, typically in a separate chamber from the one or more plasma torches, and is then condensed to produce water. The resulting water is purified of many components and/or impurities, including salts and metals, and can be potable water. The system of the invention can include multiple groups of chambers for generating steam and condensing the water in a series, as with conventional multi-flash systems.

[0007] In a specific embodiment, an inlet for water supplies water to a first chamber having one or more plasma torch generators. A power or electrical wire connects the plasma torch generator(s) to one or more power supplies or generators. The plasma torch generator(s) is either fixed at a point so that it contacts the water throughout the steam generating process, or is movable in relation to the water level. The water level can be adjusted through the inlet supply to make it retain a constant fill level in the chamber or a substantially constant level, or the water level can be allowed to move up and down as steam is generated to reduce the liquid water present. Water in the chambers discussed here can be agitated or stirred, as known in the art.

[0008] One or more steam outlet ports, optionally fixed with filters or water return pipes, allows steam to exit the first chamber. The outlet ports can have a single diameter throughout or have changing or variable diameter and may contain collecting bubbles or areas, where condensed water that has not traveled the length of the outlet is collected and optionally removed or returned to a chamber, such as the initial chamber having a plasma torch generator. The steam eventually flows into a condensing area or chamber and is cooled by circulating water or cooling elements or devices known in the art. The condensed liquid water can be subjected to a subsequent round of steam generation to further purify, or be used at this point. Multiple exhaust ports, optionally fixed with pressure regulators, can be fixed at different levels of the first steam generating chamber in order to withdraw samples of steam or particular steam at a point in the chamber, i.e., steam at a particular temperature, which may have a concentration of particular impurities for the feed water initially used. Accordingly, the liquid water collection process in the condensing area or chamber can be calibrated for different types of input water and different types of impurities. Furthermore, steam output pipes can connect to other mechanical or steam-operated systems, such as heating systems or generators. One or more fans can be used to direct, vacuum, or push steam through the pipes or chambers used. As noted above, multiple steam generating chambers can be used in series with multiple water condensing areas or chambers to successively treat water.

[0009] Precipitated or solid material that collects in the steam generating or condensing chambers can be removed by flushing with an optional flushing inlet and outlet system, using water of a particular purity recycled from what is produced, or using the original input or feed water from a feed pipe. Again depending on the water used or type of impurities expected, various additives can be used in the initial feed pipe water or other stages. One of skill in the art is familiar with many such additives and can select from any available, for example, limestone, activated carbon, silica, calcium compounds, or gasses.

[0010] In general, any convenient or appropriate plasma generator and power source and gas supply can be selected, and one of skill in the art is familiar with many options to select from. The details of plasma generating devices and technology and plasma torches are well known and need not be detailed here. The process generally involves a stream of plasma arc gas introduced between the electrodes of a plasma torch generator. The stream of plasma arc gas is introduced at a selected flow while the electrodes are subjected to a selected power level to produce a plasma torch or flame in a desired or restricted area within the reactor chamber. A plasma torch or flame can be produced with any gas in this manner. To provide more control over chemical reactions in the plasma, the gas used might be neutral (for example, argon, helium, neon and the like), reductive (for example, hydrogen, methane, ammonia, carbon monoxide, and the like) or oxidative (for example, oxygen, nitrogen, carbon dioxide, and the like). The selection of gas can be made in conjunction with the water used in the chamber with the one or more plasma generators. In addition, the selection of gas can take into account the properties of the anode or electrodes in the plasma generators, so that for example, hydrogen can be minimized to prevent anode erosion. Argon gas typically produces little or no reactions at the electrodes. In addition, water-stabilized plasma devices can be used to generate even high temperatures, in the range of up to 50,000 ⁰K instead of the more typical 8,000 to 10,000 °K for gas plasma systems {see, for example, Hrabovsky, Pure & Appl Chem, 70: 1157-1162 (1998)). Of course, the temperature used for particular water sample or particular chamber size can be selected, as known in the art.

[0011] The plasma torch or flame can be generated from either an AC or DC power supply in short pulses, in long pulses, or for a continuous period of time to produce the desired amount of steam or generate a certain internal pressure and/or temperature within the chamber. A combination of the pulses or plasma torch exposure periods can also be selected.

[0012] The water in the first or steam-generating chamber, which contains the one or more plasma generators, can be circulated continuously, removed at intervals after treatment, partially removed to reduce the dissolved components that may concentrate during the steam generation process, or may be mixed continuously or at intervals with fresh water from a supply line or pipe. A steam escape pipe or outlet from the first chamber allows the steam to pass to another chamber or area to be condensed by cooling, usually through a separate group of cooling pipes or elements either inside or in contact with this chamber. The condensed water is typically pooled and collected and stored for either further treatment or use. As noted above, a series of steam generating chambers with one or more plasma devices and connected to a condensing chamber or area can be used to successively generate steam and condense purified water. In addition, any of a variety of filters, such as activated carbon filters, can be used in the steam pipe or outlet, in the connection between the condensed water chamber or area and a successive steam generating chamber, or at the end of the steam-generating and condensing process.

[0013] The devices, systems and method of the invention can be used with a variety of water sources and water supplies, for example seawater, brakish water, well water, and water from lakes, rivers and streams.

[0014] The amount of energy used by present desalting technologies is quite high relative to the energy to separate salt from seawater. If the free energy requirement for desalting seawater is approximately 3.7 kWh/1000 gallons or 1.0 k m3 at 25 °C, then a typical brackish water RO unit (operating at 1000 psi (6.9 MPa) pressure, 30% water recovery, and 70% pump efficiency) consumes 33 kWh/1000 gallons (8.7 kWh/m3). Depending on the water used, the purity requirements, and the type of system incorporating the plasma generator devices, systems, or methods of the invention, the efficiency of desalting can be increased from that discussed above for a typical RO process. However, in embodiments where mobility and fast generation of water are important, efficiency may not be a primary concern.

[0015] In another aspect, the water treatment device or system of the invention can be combined with a building or other heating water circulation system, such as a closed loop steam-heat radiator system, to provide steam from one or more plasma generators. The methods can be similarly adapted. For example, the steam generated in a first chamber can be coupled to a system of pipes and radiators for circulating heat throughout a building or structure.

[0016] In general, the one or more plasma generators can be incorporated into a mobile or easily moveable unit or vehicle so that water treatment can be sent to an area where it is needed. This provides an essentially unlimited supply of potable water at its needed site and avoids the necessity of routine or emergency shipments. A similar device or system can essentially form a back-up water supply for residential, industrial, or municipal water. In some aspects, a gasoline-powered or diesel- powered generator on a truck, for example, can be used to power the plasma generators. In general, the plasma generator employs any power source or supply available. [0017] In one preferred embodiment of the plasma torch generator that can be selected, a first voltage is applied between the anode and cathode to cause an arc to form. Pressurized gas is applied to the arc or to the gap between the anode and cathode via a gas passage. As used here, "gas" can be some inert gas or other gas that does not interfere with the generation of a plasma torch, or it can be air. A current is then applied to generate a plasma torch, wherein the plasma torch generator is positioned so that a plasma torch is capable of contacting water or the surface of water. The order of the steps listed above, or elsewhere in the methods of this invention, need not necessarily be exactly the same as written. Similarly, the invention encompasses a method for calibrating a plasma torch generator to generate steam. The method can comprise altering one or more of a number of factors involved in or known to be involved in generating a plasma torch. For example, the type of cathode or anode used, the gap between the cathode and the anode, the voltage used, the pressure of the gas or air, the duration of the plasma torch, the size of the plasma torch, the temperature generated in water in contact with the plasma torch, can all be varied to optimize, either one factor at a time or more than one factor, to generate a desired plasma torch. One of skill in the art is familiar with methods and techniques to vary each of these factors.

[0018] A particular embodiment employs one or more or all of: a vortex cathode; a continuous air flow over the cathode/anode of about 3 to about 5 bar; a pressurized air supply at about 3 to about 5 bar or from about 3 to about 10 bar; an initial arc generating voltage of between about 3 kV and about 20 kV; a torch generating a current pulse, or high current pulse, of approximately 15 amps, whereby a 85 V/ 15 amp pulse crosses the anode/cathode gap; a power source for generating an initial arc and a separate power source for generating a current pulse; a nickel plated copper cathode; a copper anode; a torch guide; and a tungsten torch guide to direct the torch at water, for example.

[0019] In an embodiment where an anode surrounds a vortex cathode, the anode and vortex cathodes are electrically connected to a power supply or generator. An electrical contact with the anode and the power supply cause an arc to form across an anode/cathode gap. A cathode insulator prevents a short circuit between the anode and the vortex cathode. Air or gas flows from an air/gas supply to the anode/cathode gap. A connector provides a path for electrically connecting the vortex cathode to the power supply. Preferably, the gas used is high-pressure air. Other gases, for example Argon or Nitrogen, can be used as noted above. Air flow preferably is continuous to protect the components from discharge gases reentering the mechanism and fouling the cathode/anode air flow. Air flow can also be used to, or can function to, cool the anode and cathode or insulators.

[0020] In general, the plasma torch can be generated by first causing an arc to form across a gap between a cathode (preferably a vortex cathode) and an anode. In one example, 3 kV to 20 kV across the anode/cathode gap generates an arc, but many other voltages or methods can be selected. The voltage can be applied across the anode/cathode gap for a specific period of time or to generate a specific pressure within a chamber or a specific amount of vapor or steam. A current pulse or high current pulse from a power source to the cathode/anode gap and pressurized gas or air flowing between the cathode and anode generates a plasma torch, or extends the plasma arc into a plasma torch, which plasma torch is capable of contacting water.

[0021] The power supply may use a first generator to supply the voltage to create an initial arc and a second generator to supply the current to generate the plasma torch. Alternately, a single generator capable of varying its voltage and current may be used. Thus, one of skill in the art can substitute a variety of electrical elements to construct a suitable power supply for generating a plasma torch in accordance with the present invention. In the two generator embodiment, a first generator is energized to apply a voltage across the anode/cathode gap, generating an arc. The voltage is preferably between about 3 kV and about 20 kV. A current of about 15 amps, which also produces about 85 volts, generates a plasma arc. A range of currents can be used beyond the approximately 15 amps of current exemplified here, as one of skill in the art understands. When initiated by a water level indicator or other initiating signal from the system, a gas supply applies high pressure gas through the gas passage to extend the plasma arc into a plasma torch that extends towards water. The pressure of the high pressure gas is preferably between about 3 to about 5 bars. The second generator is a high voltage generator that is synchronized with the flow of gas from the gas supply. Shortly after the high-pressure gas is introduced, the second generator is energized to apply approximately 15 amps from cathode to anode for a short duration, preferably selected to a particular vapor or steam generation level. A conventional control switch can be used to activate the plasma torch, as described for the Drag-Gun product or other available plasma torch device (see, for example, http://www.thermodyne.com or http://www.thermadyne.com/tdc/literature/index.asp?div=tdc). Of course, one of skill in the art is familiar with ways to modify and automate the control switch to provide, for example, multiple voltage and current pulses for each activation, operator input can cease the control switch from generating successive plasma torches. In this and other embodiments of the invention, a conventional DC current can be used, although certain embodiments can use AC current. At a 15 Amp setting, a range of voltages can be employed and using air pressure at 5 bar and a cathode/anode gap of approximately 0.625 mm. A conventional torch generator can be modified to expel a continuous air pressure of 5 bar and to vary the power output. Voltage settings between 10 V and 100 V/ 15 A can be initially tested.

[0022] A test for efficiency can use 1 liter of water and one plasma generator to heat it one degree C. A measurement of the amount of energy and the time it takes to raise one degree ⁰C calculates the kcal used. This can be compared to other systems, such as the conventional multi-flash distillation at about 12 kW/hour. The water vapor can also be tested for the degree of electrolysis or H2 or 02 or O3 generation. Successive tests using 85 volts and 15 amps in a continuous and pulsing mode can be used for temperature control and steam generation control. A pulsing mode for the plasma torch may be used to allow fine temperature regulation, if desired.

[0023] In one aspect, a desalination or distillation system of the invention can essentially be an improvement in current multi-stage flash systems through the use of plasma torches or flames tc produce steam or water vapor. The steam or water vapor production can occur quickly, nearly instantaneously, and in certain embodiments in only a single chamber. Other designs require multiple heating chambers or multiple heating steps. In another aspect, the water purification, distillation, or desalination system can be incorporated into a mobile or transportable unit. A portable plasma torch generator, or other appropriate plasma generator, can be selected for such use.

In other embodiments, the desalination or general distillation system of the invention may incorporate any number of known or available distillation systems, including, but not limited to, a single-effect distillation system and a solar distillation system. Regardless of the particular embodiment, the principle of distillation allows water of a selected source to change from liquid to vapor and back to liquid, but in a purified form.

The examples and description given here are intended to show merely optional configurations for the devices and methods of the invention. Variations, modifications, and additional attachments can be made by one of skill in the art. Thus, the scope of the invention is not limited to any specific example or any specific embodiment described herein. Furthermore, the claims are not limited to any particular embodiment shown or described here. Other embodiments and advantages of the invention will be obvious from this description or may be learned from the practice of the invention.

Claims

What is claimed is:

1. A method for using a plasma generating device in a water treatment apparatus or system, comprising

providing one or more plasma generators within a chamber that is capable of being at least partially filled with water,

providing a power supply and air or gas supply to the one or more plasma generators to generate one or more plasma torches, where the one or more plasma torches are positioned to contact the water in the chamber,

collecting the steam generated from the one or more plasma torches, and

condensing the steam to produce water.

2. The method of claim 1 , wherein the plasma torch generator comprises a vortex cathode.

3. The method of claim 1 , wherein the chamber is of a size that can be carried in a mobile unit, such a motor vehicle, automobile, or truck.

4. The method of claim 1, further comprising using the water produced and repeating the steps of generating one or more plasma torches and collecting the steam generated to produce a further water.

5. The method of claim 3 , wherein the plasma torch generator comprises a vortex cathode.

6. A water distillation or desalination apparatus comprising: a chamber comprising a plasma torch generator and a water feed line, wherein the chamber is of a size compatible with its transport in a motorized vehicle or truck; a power supply or generator connected to the plasma torch generator and capable of causing a plasma torch to be generated; a steam output port connected to the chamber; and a water condensing chamber connected to the steam output port.

7. The apparatus of claim 6, wherein the plasma torch generator comprises a vortex cathode.

8. The apparatus of claim 6, further comprising a filter in line with the steam output port.

9. The apparatus of claim 6, further comprising a line connecting the steam output to the chamber.

10. The apparatus of claim 6, further comprising a second chamber comprising a plasma torch generator connected to the water condensing chamber.