Patent Application
20180141826
The present application relates generally to the field of desalination of liquids. Embodiment of the disclosure relate to a desalination system and method.
Fresh water shortage affects roughly one-third of the world's population and is becoming more critical in recent years due to drought, population increase, development of population centers in arid areas, and pollution. About 97.5% of the water on earth is saltwater and the remaining about 2.5% is fresh water. Therefore, a practical, economically viable desalination process is crucial to overcoming this crisis. For these reasons, and others, desalination is an important issue.
Desalination can be accomplished by a number of methods known in the art. Conventionally, the most commonly used desalination process involves variations of one or more thermal processes, for example evaporation. Although these thermal methods involve a high energy requirement, energy integration and recovery make them reasonable efficient for low salinity solutions. Energy requirements for thermal methods increase significantly as solution salinity increases. Other known desalination methods include membrane processes, e.g. filtration methods such as reverse osmosis (RO). Although membrane performance gradually has improved, membrane technology are typically used for low salinity brines such as brackish water are sea water. Treatment of high salinity brines remains high energy demand process making it economically challenging.
Freeze crystallization is a thermal desalination process wherein saline water is chilled to a temperature sufficient for the saline water to freeze. It is based on the fundamental principle that the structure of an individual ice crystal does not accommodate salts. As a result, ice crystals, formed after water in brine freezes and is separated from the resulting salt crystals, consist of pure water. These pure ice crystals can then be separated from the salt crystals and melted to form pure water.
In operation, freeze crystallization can be achieved by direct cooling or indirect cooling. As water in brine freezes forming pure ice, salt remains in the brine solution until salt concentration reaches the saturation point (eutectic point). As more heat is removed from the solution, salt is crystallized. Typically, in existing freeze based processes ice floats on the top of the brine solution while salt crystals are collected on the bottom. After ice is collected, it is melted to produce non-saline, drinking or potable water (for example, water with less than 100 ppm salinity).
Despite its potential, the freeze crystallization process has not been successfully implemented on a large, commercial scale. Historically, there have been three principal challenges: (i) the difficulty in using refrigeration systems to efficiently freeze large quantities of saline water without forming large chunks of ice; and (ii) equipment/plant complexity. Systems that utilize indirect cooling (e.g. external refrigeration) require large vessels to hold the saline water, which results in inefficient heat transfer between the refrigerant and the saline water. Direct refrigerant injection into the saline water exhibits a higher heat transfer surface area, but requires the additional step of the recovering refrigerant from the saline water. In both methods, the complexity of handling and separating the brine/ice slurry remains an obstacle.
Because of the drawbacks of the existing desalination and freeze crystallization methods discussed above, there is a need for a highly efficient and cost effective desalination method that allows fresh drinking (i.e. potable) water to be produced. The method disclosed herein solves the obstacles of conventional freeze desalination technologies by providing an energy efficient method to form ice crystals without limitations of existing systems. The resulting ice and salt crystals can be easily separated, thus reducing the equipment complexity often required for conventional freeze crystallization processes. The method disclosed herein also allows for 100% water recovery from brine producing pure water and salts.
It therefore is an object of the present disclosure to provide a novel, cost-effective and efficient process for desalinating high salinity brine using a controlled freeze method, wherein direct contact between a cold expanding stream of compressed fluid and saline water droplets allows for the production of ice crystals (containing pure water) and salt crystals to be formed, whereby the salt ions diffuse toward a center of the droplet during the freeze process and form salt crystals. The salt and water crystals can then be readily separated. As described herein, the energy required for the saline water cooling and freezing is provided by the expanding and cooling of compressed fluid and vaporization of the fluid.
The process disclosed herein is fast, reduces energy requirements, has less complex and smaller equipment, a high fresh water production (potential of 100%), and is more cost efficient for treatment of high salinity water than other methods.
These and other shortcomings of the prior art are addressed by the present disclosure, which includes a desalination system and a desalinating process.
In accordance with one embodiment, a system for desalination is provided. The system comprises a feed source of saline water, a feed source of at least one refrigerant, a compressor, a condenser, at least one expansion device, a freezing chamber and at least one injector. The compressor comprising an input fluidly coupled to the source of said at least one refrigerant and an output, and configured to generate a compressed vaporized refrigerant. The condenser comprising an input fluidly coupled to the compressor and an output. The condenser operatively configured to simultaneously melt frozen saline water droplets and generate a chilled, partially liquefied refrigerant stream. The at least one expansion device comprising at least one input fluidly coupled to the condenser and at least one output configured to release the chilled refrigerant stream at a refrigerant stream injection velocity. The freezing chamber comprising at least one input to introduce the chilled refrigerant stream into the chamber, and a first and second output. The at least one injector configured to introduce the saline water into the freezing chamber in the form of saline water droplets to freeze the saline water droplets. One or more parameters relative to the saline water droplets and the chilled refrigerant stream provide for a controlled freezing of the saline water droplets to promote salt ions in the saline water droplets to diffuse towards a center of each of the frozen saline water droplets and form salt crystals in a center of each frozen saline water droplet surrounded by ice crystals comprising pure water.
In another aspect of the present disclosure, the desalination system comprises a desalination system. The system comprises a compressor, a condenser, an expander, and a freezing chamber. The compressor, the condenser, the expander and the freezing chamber are connected in a closed system to circulate a refrigerant stream. The system further comprises an injector configured to introduce simultaneously into the freezing chamber the refrigerant stream and a saline water stream in the form of saline water droplets. One or more parameters relative to the saline water droplets and the chilled refrigerant stream provide for a controlled freezing of the saline water droplets to promote salt ions in the saline water droplets to diffuse towards a center of each of the frozen saline water droplets and form salt crystals in a center of each frozen saline water droplet surrounded by ice crystals comprising pure water.
In another aspect of the present disclosure, a desalinating process is provided. The desalinating process comprises the steps of: (a) providing at least one refrigerant and a feed source of saline water; (b) compressing the at least one refrigerant to generate a compressed vaporized refrigerant stream; (c) condensing the compressed vaporized refrigerant stream to generate a partially liquefied, chilled refrigerant stream; (d) expanding the partially liquefied, chilled refrigerant stream through an expansion device to generate a chilled refrigerant stream; (e) injecting the saline water into a freezing chamber in the form of saline water droplets; (f) freezing the saline water droplets) to form frozen saline water droplets by contacting the saline water droplets with the chilled refrigerant stream in the freezing chamber in a controlled freeze process to promote salt ions in the saline water droplets to diffuse towards a center of each of the frozen saline water droplets and form salt crystals in a center of each frozen saline water droplet surrounded by ice crystals comprising pure water; (g) removing the frozen saline water droplets from the freezing chamber and delivering to an ice melter; (i) melting the frozen saline water droplets to generate pure water and salt crystals; and (j) withdrawing pure water from the ice melter.
Various refinements of the features noted above exist in relation to the various aspects of the present disclosure. Further features may also be incorporated in these various aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to one or more of the illustrated embodiments may be incorporated into any of the above-described aspects of the present disclosure alone or in any combination. Again, the brief summary presented above is intended only to familiarize the reader with certain aspects and contexts of the present disclosure without limitation to the claimed subject matter.
These and other features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: in accordance with one or more embodiments shown or described herein;
Reference now will be made in detail to embodiments of the disclosure, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the disclosure, not limitation of the disclosure. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the scope or spirit of the disclosure. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present disclosure covers such modifications and variations as come within the scope of the appended claims and their equivalents.
Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about,” is not limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Range limitations may be combined and/or interchanged, and such ranges are identified and include all the sub-ranges stated herein unless context or language indicates otherwise. Other than in the operating examples or where otherwise indicated, all numbers or expressions referring to quantities of ingredients, reaction conditions and the like, used in the specification and the claims, are to be understood as modified in all instances by the term “about.”
“Optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, or that the subsequently identified material may or may not be present, and that the description includes instances where the event or circumstance occurs or where the material is present, and instances where the event or circumstance does not occur or the material is not present.
As used herein, the terms “comprises”, “comprising”, “includes”, “including”, “has”, “having”, or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article or apparatus that comprises a list of elements is not necessarily limited to only those elements, but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
As used herein, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise.
As used herein, the term “saline water” refers to the water that contains a significant amount of at least one kind of dissolved salt at a given temperature. It can also be referred to as, or used interchangeably with, the terms “salt water”, “sea water”, “brackish water”, or “brine”.
As used herein, the term “purified water” or “pure water” or “fresh water” means water containing no or low concentrations of dissolved salts, and more specifically water having a salinity of less than 0.05% at a given temperature.
For purposes of this application “drinking water” or “potable water” is defined as fresh water that is safe enough for drinking or food preparation.
As used herein, the term “vessel” or “tank” includes storage mediums known in the art, including but not limited to pipes, containers, chambers, reservoirs, vats, and other receptacles.
As used herein, the term micron (μ) and micrometer (μm) are interchangeable and defined as an SI derived unit of length equaling 1×10−6 of a meter.
Embodiments of the present disclosure include a desalination system using a freeze method, wherein direct contact between a cold expanding stream of compressed fluid and saline water droplets allows for the production of ice crystals (containing pure water) and salt crystals to be formed, whereby the freeze process is controlled to provide the salt ions to diffuse toward a center of the droplet and form salt crystals during the freeze process. The salt and water crystals can then be readily separated in an integrated heat exchanger.
As previously indicated the current disclosure provides for a method of desalination using a freeze process and the separation thereafter of the salt crystals and melted ice crystals to provide salt and potable water. Referring now to the drawings, it is noted that like numerals refer to like elements throughout the several views and that the elements shown in the Figures are not drawn to scale and no dimensions should be inferred from relative sizes and distances illustrated in the Figures. Illustrated in
Referring still to
In an embodiment of the present disclosure, the at least one pump 24 provides for compressing of the input saline water 30 and for the introducing of the saline water 30 into the second heat exchanger 26 and an expansion device, such as an ejector or nozzle 28. In an alternate embodiment, the expansion devices 20 and 28 may comprise any type of expander known in the art. One of ordinary skill in the art will recognize that the fluids circulating through system 10 can flow through the system via known-in-the-art mass-transport forces, such as pumping, gravity, pressure, and suction.
In embodiments of the present disclosure, the at least one refrigerant 40 is capable of at least partially condensing into a liquid at temperatures slightly above 0° C. In one embodiment, the refrigerant is propane or ammonia. In still other embodiments, the refrigerant is a chlorine-bearing or fluorine-bearing carbon compounds, hydrocarbons, methyl chloride, and/or mixtures thereof. By way of example only, the hydrocarbon could be propane, iso-pentane, butane, iso-butane, pentane and mixtures thereof. Additional refrigerants would include any chlorofluorocarbon (CFC), hydrochlorofluorocarbon (HCFC), or hydrofluorocarbon (HFC) refrigerant. One of ordinary skill in the art will recognize, however, that any refrigerant that is capable of changing phase to at least partially condense at practical temperatures and pressures (i.e. mild conditions) for a large-scale system is suitable.
More specifically, a refrigerant that absorbs heat by evaporating below the freezing point of water (32° F./0° C.) while at a relatively low pressure, is attractive. On the other hand, the same refrigerant must be able to condense at temperatures not greatly higher than normal ambient temperatures and at pressures attainable by modern compressors. Furthermore, the use of air as a refrigerant is contemplated and is within the scope of this disclosure. One of ordinary skill in the art would recognize, however, that if air is used as the refrigerant the configuration of system 10 would be modified.
Referring still to
Referring still to
As alluded to previously, the cooled pressurized compressed vaporized refrigerant 42 is next passed through the condenser 18. In the embodiment shown here, the condenser 18 is operatively configured to further cool and condense the cooled pressurized compressed vaporized refrigerant 42 into the chilled, partially condensed (liquefied) refrigerant stream 44 via indirect heat exchange. For example, condenser 18 is an ice melter 19 configured to melt ice crystals (described presently) delivered from the freezing chamber 22 (e.g. at the back-end of the process). In this way, the ice melter 19 both generates a pure water stream 50, by separating out the salt crystals 38 from the water stream 50, and also condenses the cooled pressurized compressed vaporized refrigerant 42 to generate the chilled, partially condensed (liquefied) refrigerant stream 44 via indirect heat exchange. In this embodiment, condenser 18 further comprises a cooled pressurized compressed vaporized refrigerant input 18a, a condensed refrigerant stream output 18b, a frozen saline water droplet input 18c, a salt crystal output 18d and a pure water stream output 18e. The input 18c is fluidly coupled to an output of the freezing chamber 22, the salt crystal output 18d is coupled to an optional salt crystal storage tank 62 for the storage therein of the separated salt crystals 38, and said output 18e is coupled to a pure water storage tank 52 for the storage therein of the pure water 50. While it is contemplated that system 10 can include other conventional devices or units capable of condensing the cooled pressurized compressed vaporized refrigerant 42 from its gaseous to its liquid state by cooling it, the embodiment illustrated in
The chilled, partially condensed (liquefied) refrigerant stream 44, which is at least partially-liquefied and in the thermodynamic state known as a saturated liquid, is next routed through the expansion device 20 where it undergoes an abrupt reduction in pressure and lowers the temperature of the liquid and vapor refrigerant mixture. In this particular embodiment, the expansion device is a Joule-Thomson (JT) valve 21, whereby the chilled, partially condensed (liquefied) refrigerant stream 44 is expanded such that liquid portion of the refrigerant 44 is evaporated due to the pressure change and further cools the chilled vapor refrigerant stream 46. One of ordinary skill in the art will recognize that any conventional expander capable of converting compressed fluids into an expanded, chilled vapor and also capable of handling multi-phase fluids (e.g. 2 or preferably, 3, phases) can be used. The expansion device 20 produces a chilled stream of refrigerant 46, which in turn lowers the temperature in the freezing chamber 22 to the desired temperature to freeze the injected saline water droplets (described presently).
Referring to
In accordance with this disclosure, regardless of the specific device used, the expansion device 20 is capable of receiving an input in the range of about 44 pounds per square in absolute or psia (SI units=303369 Pa) to about 220 psia (SI units=1516847 Pa) and of producing an output in the range of about 14.7 psia (SI units=101353 Pa) to about 44 psia (SI units=303369 Pa). In embodiments of the present disclosure, the requisite input and output capacities for the expansion device will vary and depend on the characteristics of the fluids and other environmental factors. For example, in some embodiments the input capacity will be 44, 45, 50, 55, 65, 25, 27, 30, 35, 50, 100, 120, 150, 200 or 220 psia, including any and all values, ranges and subranges therein (e.g., 44 to 220 psia, 44 to 60 psia, 44 to 100 psia, 50 to 200 psia, 50 to 150 psia, 100 to 220 psia, 70 to 100 psia, 200 to 220 psia, etc.). In some embodiments the output capacity will be 14.7, 15, 16, 20, 23, 25, 25, 27, 30, 32, 35, 40, 43 or 44 psia, including any and all values, ranges and subranges therein (e.g., 14.7 to 44 psia, 16 to 44 psia, 25 to 44 psia, 30 to 40 psia, 14.7 to 22 psia, 14.7 to 30 psia, 20 to 30 psia, 40 to 44 psia, etc.). For purposes of the above values, one of ordinary skill in the art will recognize that the US customary unit for pressure, pounds per square inch absolute (psia) is equivalent to and can be converted to SI units using a conversion of 1 psia is equal to 6894.75728 pascal (Pa).
The freezing chamber 22 is operatively configured to provide direct contact between the chilled stream of refrigerant 46 and a cooled saline water stream 32 exiting the second heat exchanger 26. The freezing chamber 22 has an inner surface that defines a volume and the size and configuration of the chamber 22 can vary, depending on the system needs and capacities required. Further, in an embodiment the freezing chamber 22 includes a first inlet 22a from which the chilled stream of refrigerant 46 enters the freezing chamber 22, a second inlet 22b from which the compressed saline water 32 enters the freezing chamber 22, a first outlet 22c from which the refrigerant vapors exit the freezing chamber 22 as a vapor stream 48 and are recycled back to compressor 12 to form a closed loop refrigeration system and a second outlet 22d from which frozen saline water droplets 36 comprising ice crystals 37 and salt crystals 38 formed therein a center of the droplets, exit the freezing chamber 22. In an embodiment, the at least one injector 28 is configured to introduce the cooled saline water 32 into the freezing chamber 22 in the form of saline water droplets 34. When the saline water droplets 34 contact the incoming chilled stream of refrigerant 46, the refrigerant cools the droplets and the saline water droplets 34 freeze to simultaneously form the ice crystals 37 and the salt crystals 38, whereby the ice crystals 37 are allowed to freeze in a manner that provides for the salt ions to diffuse toward a center of the saline water droplets 34 during the freeze process.
More particularly, during the freeze process, the freeze time of the saline water droplets 34 may be controlled/adjusted based on the size of the input saline water droplets 34. During the droplet freeze process the freeze time may be adjusted to provide sufficient time for the salt ions in the saline water droplets 34 to diffuse towards the center of the saline water droplets 34 and form the salt crystals 38. Accordingly, larger saline water droplets 34 will require a longer freeze time within the freezing chamber 22. To provides such controlled freezing and diffusion of the salt ions to the center of the droplets 34, the freeze time may be adjusted by such process parameters as: (i) the temperature of the chilled stream of refrigerant 46; (ii) the amount of the chilled stream of refrigerant 46 relative to the amount of saline water droplets 34 injected; (iii) the injection velocity of the saline water droplets 34 relative to the flow of the chilled stream of refrigerant 46; (iv) the droplet size of the saline water droplets 34; and (v) the size of the freezing chamber 22. The size of the saline water droplets 34 may be adjusted by selection of the size of the at least one injector 28.
In further accordance with the described employing of controlled freezing and diffusion of the salt ions to the center of the droplets 34, in an embodiment of the present disclosure, the temperature of the chilled stream of refrigerant 46 in the freezing chamber is about 0° C. to about −50° C. For example, in some embodiments refrigerant stream has temperature of 0-50° C., including any and all values, ranges and subranges therein (e.g., 0 to −50° C., 0 to −48° C., 0 to −45° C., 0 to −20° C., 0 to −10° C., 0 to −5° C., 0 to −2° C., −2 to −50° C., −5 to −40° C., −2 to −30° C., −21 to −23° C., −21 to −25° C., etc.). While not meant to be limiting, in preferred embodiments, the temperature is approximately 0° C., or a little below 0° C. (e.g. −1° C., −2° C., −5° C.).
The injector 28 is preferably equipped with a nozzle configured to introduce the cooled pressurized saline water 32 into the freezing chamber 22 in the form of a spray comprising the saline water droplets 34. In further accordance with the described employing of controlled freezing and diffusion of the salt ions to the center of the droplets 34, in an embodiment of the present disclosure, the injector 28 is a sprayer comprising a nozzle operatively configured to introduce the saline water droplets 34 with an initial diameter (di) less than 1 mm in diameter, more preferably an initial diameter (di) of about 200 microns (μ) to about 1000 microns (μ), into freezing chamber 35. For example, in some embodiments, saline water droplets with an initial diameter (di) of 200, 201, 205, 210, 250, 300, 350, 400, 500, 550, 600, 700, 800, 900, 995, 999, 1000 microns, including any and all values, ranges and subranges therein (e.g., 200 to 1000 microns, 200 to 999 microns, 200 to 900 microns, 200 to 700 microns, 200 to 500 microns, 200 to 250 microns, 201 to 1000 microns, 205 to 999 microns, 500 to 1000 microns, 600 to 900 microns, etc.).
While any size and variations of injector configurations are contemplated, the configuration of injector 28 is sufficient to produce a minimum spray water droplet size in the range of less than 1 millimeter (mm). Injector 28 will also be selected in accordance with the pressure, spray angle and distribution pattern required for the particular system and conditions, and generally speaking, an injector configuration that operates at higher pressures will produce saline water droplets with a smaller initial diameter, thus providing a slower freeze time to allow for the diffusion of the salt ions to the center of the saline water droplets 34. Although not meant to be limiting, in the examples disclosed herein, the injector operates at saline water pressures in the range of about 2 bar to about 10 bars.
In operation, dependent upon certain parameters of the incoming chilled stream of refrigerant 46, the incoming cooled saline water 32 and droplet size, the system enables the saline water droplets 34 to freeze within a specific residence time (or “RT”). For purposes of this disclosure, residence time is defined as the average amount of time a particle (or, in this case, a water droplet) will spend in the freezing chamber 22 under set conditions. As is typical in the art, the residence time is calculated from the moment a particle enters the freezing chamber 22 and ends the moment it would leave the freezing chamber 22. However, one of ordinary skill in the art will recognize that it will change and can be defined as needed according to the application, the inflow and outflow rates, droplet size and the size of the desalination system (e.g. size of the turbo expander). As previously described, the residence time may be adjusted to provide for sufficient time for the salt ions in the saline water droplets 34 to diffuse toward a center of the droplets 34 and form salt crystals 38, surrounded by formed ice crystals 37.
For example, a characteristic residence time of a particle in the freezing chamber 22 is in the range of about 100 milliseconds (ms) to about 10000 milliseconds (ms) Furthermore, it is contemplated that in some embodiments, the RT will be 100, 205, 310, 450, 580, 600, 750, 880, or 10000 ms, including any and all values, ranges and subranges therein (e.g., 100 to 10000 ms, 210 to 10000 ms, 320 to 490 ms, 321 to 550 ms, 600 to 800 ms, 450 to 10000 ms, 100 to 200 ms, 100 to 150 ms, 100 to 130 ms, 100 to 410 ms, 200 to 750 ms, etc.).
In accordance with embodiments of the present disclosure, the size of the saline water droplet 34 is controlled and predetermined to ensure that proper freezing occurs during the calculated residence time (RT) in the chamber, and so as to allow for diffusion of the salt ions to the center of the droplet 34. By way of example, if a freezing chamber 22 has a residence time of about 10 milliseconds (ms), the droplet size injected into the chamber 22 should be selected to provide for direct contact between all of the saline water droplets 34 and the chilled stream of refrigerant 46, thus ensuring that the cooling of the saline water droplets 34 by direct contact with the chilled stream of refrigerant 46 will produce an efficient heat transfer between the refrigerant and the saline water and provide sufficient time for diffusion of the salt ions.
As the saline water droplets are super-cooled, or frozen, in the chamber 22, the salt ions diffuse toward the center of each saline water droplet, providing for the formation of frozen saline water droplets 36 comprising ice particles or crystals about the centralized salt particles or crystals. Referring still to
As shown in
In embodiments of the present disclosure, the system 10 may further include a controller 55, external or internal, operable to control the desalination system, control the flow of water and refrigerant through the system, as well as to provide the proper functionality and parameters and/or setting for the system.
In an exemplary embodiment, system 10 is configured for use in a continuous manner for purifying the saline water 30. The salinity of the pure water stream 50 exiting desalination system 10 through the condenser 18 will be less than the salinity of the source saline water 30 entering the desalination system 10. In accordance with the embodiments of the present disclosure, the difference in salinity will range from about 80 to about 99%. While the system described above may be sufficient in most applications, the system may optionally include an evaporator (not shown) and/or a crystallizer (not shown), or employ other methods and/or systems known in the art, to provide 100% water recovery.
In alternate embodiments, the method and system may incorporate a device to mechanically remove the frozen saline water droplets from the freezing chamber. Further, while not illustrated, other mechanisms, such as pumps (to draw water through the system or to/from other components in the system) may be used in accordance with the skills and methods known in the art. Furthermore, the components for the desalination system may be made of suitable materials. Suitable materials may include one or more material selected from metal or plastic. Further embodiments, and alternate configurations, for the desalination system are disclosed in copending patent application bearing Ser. No. 14/983,658, filed Dec. 20, 2015, entitled “Water Desalination System and Method for Fast Cooling Saline Water using Turbines” by Lissianski et al. and assigned to the same assignee as the present disclosure and incorporated herein by reference in its entirety.
Referring to
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From the above results, it will be appreciated that the use of a freeze or cooling process for desalination in which the freeze time is controlled to provide for the diffusion of the salt ions toward a center of each frozen saline droplet demonstrates an effectiveness which is both unexpected and unanticipated based on the performance of other common desalination methods, including other freeze crystallization methods. In addition, because the freeze crystallization process is operated at low temperatures, it greatly mitigates and/or avoids the scaling and membrane fouling issues that occur in other thermal and membrane processes, thereby allowing a wider selection of materials and a reduction in chemical usage to combat scaling/fouling. The process and system disclosed herein has a small footprint and low capital cost, therefore making it appropriate for a wide variety of applications, including both large scale operations and small scale operations (e.g. mobile units).
Energy requirements for the process disclosed herein are estimated to be about 45% less than that for other thermal crystallizer applications. For example, in one embodiment, 100% water recovery from 18% salinity brine using propane as a refrigerant required energy in the amount of 18 Watt-hours/liter (68 kWh/1000 gal) of brine. The process also is particularly well-suited for treatment of high salinity water and brine and embodiments of the present disclosure disclosed herein unexpectedly and effectively can treat high salinity water with reduced energy consumption (and cost).
It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the various embodiments without departing from their scope. While the dimensions and types of materials described herein are intended to define the parameters of the various embodiments, they are by no means limiting and are merely exemplary. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the various embodiments should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Further, the limitations of the following claims are not written in means-plus-function format and are not intended to be interpreted based on 35 U.S.C. § 112, sixth paragraph, unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure. It is to be understood that not necessarily all such objects or advantages described above may be achieved in accordance with any particular embodiment. Thus, for example, those skilled in the art will recognize that the systems and techniques described herein may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.
While this disclosure has been described in conjunction with the specific embodiments described above, it is evident that many alternatives, combinations, modifications and variations are apparent to those skilled in the art. Accordingly, the preferred embodiments of this disclosure, as set forth above are intended to be illustrative only, and not in a limiting sense. Various changes can be made without departing from the spirit and scope of this disclosure. Therefore, the technical scope of the present disclosure encompasses not only those embodiments described above, but also all that fall within the scope of the appended claims.
This written description uses examples to disclose the various embodiments, including the best mode, and also to enable any person skilled in the art to practice the disclosure, including making and using any devices or systems and performing any incorporated processes. The patentable scope of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. These other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.
This invention was made with government support under grant number DE-FE0024022 awarded by the U.S. Department of Energy. The government has certain rights in the invention.
