Patent ID: 12187625

DETAILED DESCRIPTION

To address the shortcomings in the prior art, the various embodiments of the present disclosure provide a novel zero-liquid discharge eutectic-freeze desalination technology that is particularly well suited for the treatment of highly concentrated brines produced in the industrial and oil and gas sectors. In particular, the disclosed system takes advantage of the excellent heat transfer performance of direct contact freezing systems without being affected by dissolution of the refrigerant in the purified water. The combination of superior heat transfer with high quality purified water and competitive desalination economy makes the disclosed freeze desalination technology an attractive solution for desalination of highly concentrated brines produced in a variety of industries, including but not limited to the oil and gas industry and reject brine management.

Before further describing various embodiments of the present disclosure in more detail by way of exemplary description, examples, and results, it is to be understood that the embodiments of the present disclosure are not limited in structure and application to the details as set forth in the following description. The embodiments of the present disclosure are capable of being practiced or carried out in various ways not explicitly described herein. As such, the language used herein is intended to be given the broadest possible scope and meaning; and the embodiments are meant to be exemplary, not exhaustive. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting unless otherwise indicated as so. Moreover, in the following detailed description, numerous specific details are set forth in order to provide a more thorough understanding of the disclosure. However, it will be apparent to a person having ordinary skill in the art that the embodiments of the present disclosure may be practiced without these specific details. In other instances, features which are well known to persons of ordinary skill in the art have not been described in detail to avoid unnecessary complication of the description. While the present disclosure has been described in terms of particular embodiments, it will be apparent to those of skill in the art that variations may be applied to the apparatus and/or methods and in the steps or in the sequence of steps of the methods described herein without departing from the concept, spirit, and scope of the inventive concepts as described herein. All such similar substitutes and modifications apparent to those having ordinary skill in the art are deemed to be within the spirit and scope of the inventive concepts as disclosed herein.

All patents, published patent applications, and non-patent publications referenced or mentioned in any portion of the present specification are indicative of the level of skill of those skilled in the art to which the present disclosure pertains, and are hereby expressly incorporated by reference in their entirety to the same extent as if the contents of each individual patent or publication was specifically and individually incorporated herein.

Unless otherwise defined herein, scientific and technical terms used in connection with the present disclosure shall have the meanings that are commonly understood by those having ordinary skill in the art. Further, unless otherwise required by context, singular terms shall include pluralities and plural terms shall include the singular.

As utilized in accordance with the apparatus, methods and compositions of the present disclosure, the following terms, unless otherwise indicated, shall be understood to have the following meanings:

The use of the word “a” or “an” when used in conjunction with the term “comprising” in the claims and/or the specification may mean “one,” but it is also consistent with the meaning of “one or more,” “at least one,” and “one or more than one.” The use of the term “or” in the claims is used to mean “and/or” unless explicitly indicated to refer to alternatives only or when the alternatives are mutually exclusive, although the disclosure supports a definition that refers to only alternatives and “and/or.” The use of the terms “at least one” or “plurality” will be understood to include one as well as any quantity more than one, including but not limited to, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 30, 40, 50, 100, or any integer inclusive therein, and/or any range described herein. The terms “at least one” or “plurality” may extend up to 100 or 1000 or more, depending on the term to which it is attached; in addition, the quantities of 100/1000 are not to be considered limiting, as higher limits may also produce satisfactory results. In addition, the use of the term “at least one of x, y and z” will be understood to include x alone, y alone, and z alone, as well as any combination of x, y and z.

Where the specification or claims refer to “an additional” element, that does not preclude there being more than one of the additional element. It is to be understood that where the claims or specification refer to “a” or “an” element, such reference is not be construed that there is only one of that element. It is to be understood that where the specification states that a component, feature, structure, or characteristic “may”, “might”, “can” or “could” be included, that particular component, feature, structure, or characteristic is not required to be included.

As used in this specification and claims, the words “comprising” (and any form of comprising, such as “comprise” and “comprises”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “includes” and “include”) or “containing” (and any form of containing, such as “contains” and “contain”) are inclusive or open-ended and do not exclude additional, unrecited elements or method steps.

The term “or combinations thereof” as used herein refers to all permutations and combinations of the listed items preceding the term. For example, “a, b, c, or combinations thereof” is intended to include at least one of: a, b, c, ab, ac, bc, or abc, and if order is important in a particular context, also ba, ca, cb, cba, bca, acb, bac, or cab. Continuing with this example, expressly included are combinations that contain repeats of one or more item or term, such as bb, aaa, aab, bbc, aaabcccc, cbbaaa, cababb, and so forth. The skilled artisan will understand that typically there is no limit on the number of items or terms in any combination, unless otherwise apparent from the context.

Throughout this application, the terms “about” and “approximately” are used to indicate that a value includes the inherent variation of error for the composition, the method used to administer the composition, or the variation that exists among the objects, or study subjects. As used herein the qualifiers “about” or “approximately” are intended to include not only the exact value, amount, degree, orientation, or other qualified characteristic or value, but are intended to include some slight variations due to measuring error, manufacturing tolerances, stress exerted on various parts or components, observer error, wear and tear, and combinations thereof, for example. The terms “about” or “approximately”, where used herein when referring to a measurable value such as an amount, a temporal duration, thickness, width, length, and the like, is meant to encompass, for example, variations of +20% or +10%, or +5%, or +1%, or +0.1% from the specified value, as such variations are appropriate to perform the disclosed methods and as understood by persons having ordinary skill in the art. As used herein, the term “substantially” means that the subsequently described event or circumstance completely occurs or that the subsequently described event or circumstance occurs to a great extent or degree. For example, the term “substantially” means that the subsequently described event or circumstance occurs at least 75% of the time, at least 80% of the time, at least 90% of the time, at least 95% of the time, or at least 98% of the time.

As used herein any reference to “one embodiment” or “an embodiment” means that a particular element, feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment.

As used herein, all numerical values or ranges include fractions of the values and integers within such ranges and fractions of the integers within such ranges unless the context clearly indicates otherwise. Thus, to illustrate, reference to a numerical range, such as 1-10 includes 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, as well as 1.1, 1.2, 1.3, 1.4, 1.5, etc., and so forth. Reference to a range of 1-30 therefore includes 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, and 30, as well as sub-ranges within the greater range, e.g., for 1-30, sub-ranges include but are not limited to 1-10, 2-15, 2-25, 3-30, 10-20, and 20-30. Reference to a range of 1-50 therefore includes 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, and 30, etc., up to and including 50. Reference to a series of ranges includes ranges which combine the values of the boundaries of different ranges within the series. Thus, to illustrate reference to a series of ranges, for example, a range of 1-1,000 includes, but is not limited to, 1-10, 2-15, 2-25, 3-30, 10-20, 20-30, 30-40, 40-50, 50-60, 60-75, 75-100, 100-150, 150-200, 200-250, 250-300, 300-400, 400-500, 500-750, 750-1,000, and includes ranges of 1-20, 10-50, 50-100, 100-500, and 500-1,000. The range 1 mm to 10 m therefore refers to and includes all values or ranges of values, and fractions of the values and integers within said range, including for example, but not limited to, 5 mm to 9 m, 10 mm to 5 m, 10 mm to 7.5 m, 7.5 mm to 8 m, 20 mm to 6 m, 15 mm to 1 m, 31 mm to 800 cm, 50 mm to 500 mm, 4 mm to 2.8 m, and 10 cm to 150 cm. Any two values within the range of 1 mm to 10 m therefore can be used to set lower and upper boundaries of a range in accordance with the embodiments of the present disclosure.

In addition, techniques, systems, subsystems, and methods described and illustrated in the various embodiments as discrete or separate may be combined or integrated with other systems, modules, techniques, or methods without departing from the scope of the present disclosure. Other items shown or discussed as coupled or directly coupled or communicating with each other may be indirectly coupled or communicating through some interface, device, or intermediate component whether electrically, mechanically, or otherwise. Other examples of changes, substitutions, and alterations are ascertainable by one skilled in the art and could be made without departing from the spirit and scope disclosed herein.

The inventive concepts of the present disclosure will be more readily understood by reference to the following examples and embodiments, which are included merely for purposes of illustration of certain aspects and embodiments thereof, and are not intended to be limitations of the disclosure in any way whatsoever. Those skilled in the art will promptly recognize appropriate variations of the apparatus, compositions, components, procedures and method shown below.

Turning toFIG.1, shown therein is a schematic diagram illustrating an inventive water treatment process200carried out in accordance with an exemplary, non-limiting, embodiment of a water treatment system100. Generally, the treatment process200makes use of a water-immiscible intermediate-cold-liquid (ICL) to freeze water, which is then separated from the ice, precipitated salts and remaining liquid brine. The ice can be melted to produce purified water, while the ICL is separated from brine and recirculated and cooled through a refrigeration cycle. The system can be operated in both “zero-liquid” output mode, in which the only liquid produced by the system is purified, desalinated water, or partial freeze mode, where a fraction of the water in the input brine is recovered by freezing. In zero-liquid output operation, salt and other contaminants are removed from the system as solids for facilitated disposal or downstream processing.

The treatment system100generally includes an untreated brine feed source102, a refrigerated ICL source104, a main crystallization tank106, a primary separator108, a water-brine separation module110, and an ICL-brine separation module112. The ICL source104includes an ICL tank114that contains a suitable, refrigerated ICL. Suitable ICLs include silicone-based fluids that are immiscible with water and present low health, safety and environmental risks. Some main classes of stable coolants that are liquids at a room temperature include silicate-ester (SE), silicones, and fluorinated liquids (PFC, PFE, HFE, FK). In some applications, segregated hydrofluoroethers (HFEs) available from the3M Company as Novec 7000-series fluids can be used as the ICL.

The ICL is cooled within the ICL tank114with an external refrigeration system or heat exchanger. In some applications, the ICL tank114is cooled using solar-driven absorption ammonia refrigeration, which permits refrigeration of the ICL without connection to an established electrical grid. In exemplary embodiments, the ICL is cooled to about −30° C. within the ICL tank114.

The refrigerated ICL is injected into the main crystallization tank106together with brine streams from the untreated brine feed source102and the brine recovered from the water-brine separation module110and the ICL-brine separation module112. In exemplary embodiments, the untreated brine is precooled to a temperature of about 0° C. before it is injected into the main crystallization tank106, as described below.

In the main crystallization tank106, cold ICL absorbs thermal energy from the brine, while maintaining immiscibility with the brine. The average temperature within the main crystallization tank106is maintained at about −24° C. by adjusting the flow rate of the cold ICL relative to the untreated input brine. In some embodiments, the ICL flow rate is an order of magnitude greater than the brine flow rates entering the main crystallization tank106. In some applications, the main crystallization tank106includes a paddle, stirrer or other agitation system that encourages good mixing between the ICL and the brine. In other applications, the main crystallization tank106is configured such that the injection of the ICL and brines produces sufficient mixing without additional agitation. Nozzles and manifolds may be used to more equally distribute the ICL and brine within the main crystallization tank106.

As the injected ICL comes in contact with the brine, both salt and ice crystals form. The ice-ICL-salt-brine mixture is pumped or otherwise moved from the main crystallization tank106to the primary separator108. In some embodiments, the primary separator108is a cyclonic separator that induces a rotation of the ice-ICL-salt-brine mixture. Alternatively, hydraulic or mechanical wash columns can be employed to separate the ice from the slurry. As shown inFIG.1, when ICL has a greater density than the brine, the heavier salt-ICL slurry exits from the bottom of the primary separator108and the lighter ice-brine slurry leaves from the top of the primary separator108. Within the salt-ICL slurry, the brine component may be present completely or partially as hydrohalite crystals. The lighter ice-brine slurry is a mixture of purified water ice crystals carried in a brine solution.

The cooled, separated salt-ICL slurry is provided by pumping or other means to the ICL-brine separation module112. The ICL-brine separation module112includes an ICL-brine separator116, a hydrohalite heat exchanger118, and a salt-brine separator120. Although the exemplary embodiments are not so limited, inFIG.1the ICL-brine separator116and the salt-brine separator120are each cyclonic separators that mechanically separate feed components based on density. In the ICL-salt separator116, the ICL is separated from the hydrohalite and provided directly or indirectly to the ICL tank114for refrigeration. The immiscibility and lower density of the ICL than the hydrohalite promotes good separation from the hydrohalite.

The hydrohalite is then provided to the hydrohalite heat exchanger118, where it absorbs heat from the feed brine to the main crystallization tank106. This precools the feed brine to the main crystallization tank106, while warming the hydrohalite. It will be noted that the hydrohalite heat exchanger118is a closed system in which the feed brine to the main crystallization tank106is not in direct contact with the hydrohalite. The hydrohalite heat exchanger118can use immersed coils, shell and tube, or any other type of heat exchangers that maintains the separation of the hot and cool fluids while permitting the transfer of heat between the fluids. Upon receiving heat, the hydrohalite dissociates into a mixture of pure salt and saturated brine.

From the hydrohalite heat exchanger118, the salt-brine slurry is passed to the salt-brine separator120. In exemplary embodiments, the salt-brine separator120is a cyclonic separator in which the heavier solid salt particles are separated from the lighter liquid brine. The liquid brine is directed into the feed brine to the main crystallization tank106. The solid salt particles are discharged as a solid product for disposal or downstream processing. Although the solid particles are expected to be primary sodium chloride solids, it will be appreciated that the solid particles may also include other solid minerals and contaminants.

Turning to the ice-brine separation module110, the ice-brine slurry from the primary separator108is provided by pumping or other means to an ice-brine separator122. In exemplary embodiments, the ice-brine separator122is a cyclonic separator in which the lighter solid ice particles are separated from the heavier liquid brine. The liquid brine is recirculated as feed brine to the main crystallization tank106. The solid ice crystals are melted to provide purified water.

In the embodiment depicted inFIG.1, the ice crystals are discharged from the ice-brine separator122onto a conveyor belt124, which discharges the ice crystals into a first melting tank126. The first melting tank126is configured as a heat exchanger that precools brine from the untreated brine feed source102. The warm untreated brine melts at least a portion of the ice crystals to produce purified liquid water. A portion of the purified liquid water can be provided to a wash array130that is configured to disperse purified liquid water over the ice crystals on the conveyor belt124. Alternatively, ICL at temperatures below 0° C. can be used to wash the ice without melting it. Also, the condenser compartment of the refrigeration system can be placed in the ice melting tank. This arrangement provides the required heat for melting the ice and also lowers the condenser temperature, thereby improving the coefficient of performance of the refrigeration system. The purified wash water or the ICL used for washing removes residual brine from the exterior of the ice crystals. The waste water from the wash array130and conveyor belt124is captured by a catch basin132and directed into the brine feed line. The optional wash array130ensures a higher degree of purity of the ice crystals in the first melting tank126. Purified, desalinated liquid water is produced from the melting tank126.

It will be appreciated that the first melting tank126and the second melting tank is configured as a heat exchanger. The heat exchanger126can be configured as immersed coils, shell and tube, or any other type of heat exchangers that maintain the separation of the hot and cool fluids while permitting the transfer of heat between the fluids. In some embodiments, the liquid water and ice from the first melting tank126is provided to a second melting tank128, where an external heat source is used to raise the temperature of the water to above the melting point. For example, the hot fluid used in the second melting tank128can be captured from the compression or condensing stages of the refrigeration cycle used to cool the ICL tank114.

Turning toFIG.2, shown therein is an alternate embodiment of the water treatment system100. Depending on the selected ICL and the characteristics of the wastewater brine, the ice-ICL-salt-brine mixture may separate within the primary separator108into an ice-ICL slurry and a salt-brine slurry. In this configuration, the ice-ICL slurry is provided to an ice-ICL separation module134that includes an ice-ICL separator136in addition to the conveyor belt124, wash array130and first melting tank126. The ice-ICL separator136separates (through cyclonic or other mechanical separation mechanism) the heavier ice crystals from the lighter ICL liquid. The ICL liquid is pumped back to the ICL tank114, while the ice crystals are deposited on the conveyor belt124to be washed with purified water from the first melting tank126or ICL at temperatures below 0° C. The washed solution is captured by the catch basin132and added to the feed brine line.

The salt-brine slurry produced by the primary separator108is passed to a salt-brine separation module138that includes a salt-brine separator140. The salt brine separator140can be configured as a cyclonic separator that separates the lighter brine fluids from the heavier salt crystals. The lighter brine fluids are passed to the brine feed line while the solid salt crystals are discharged for disposal or downstream processing.

Turning toFIG.3, shown therein is an alternative embodiment in which the freezing process is accomplished in two stages. Each stage is driven by a separate refrigeration system. The rationale for developing the two-stage freeze system is to breakdown the cooling load into two parts: a relatively high temperature freezing and a relatively low temperature freezing. By extracting the ice from the input brine at a relatively higher temperature, the refrigeration system driving the first stage freezing process can operate between a smaller temperature gap between the evaporator and condenser. This dramatically improves the energy efficiency of the refrigeration process due to increased Coefficient of Performance (COP) of the first stage refrigeration system. Overall energy savings up to 30% can be achieved compared to the single-stage freeze system.

In the first stage of freezing, the input brine is cooled to temperatures within a range from about −5 C to about −20 C in a first stage freezing tank142depending on the brine composition. In general, higher levels of total dissolved solids in the brine will require lower freezing temperatures. During this process, only ice crystals are formed and salt-hydrate formation is negligible. The ice-ICL-brine slurry from the first stage freezing tank142is introduced into a first wash column144, where the solid ice is separated from the liquid ICL-brine mixture. The washed ice is carried to a first stage melting tank146, where it is melted and recovered as fresh water. The cold energy of the ice in the first stage melting tank146can be recovered for cooling the condenser of the refrigeration system. The ICL-brine mixture discharged from the first wash column144is carried to a first stage ICL-brine separator148, where the ICL and brine are separated by density and discharged through separate outlets. The separated ICL is recirculated through the refrigeration system and directed back to the first stage freezing tank142.

The output brine from the first stage ICL-brine separator148is more concentrated than the input brine because a portion of the water has already been removed. The concentrated brine is introduced to the second stage freezing tank150for the second stage of freezing. In the second stage freezing tank150, the temperature is further decreased to temperatures within a range from about −24 C to −35 C. At these temperatures, both ice crystals and salt-hydrates are formed. Depending on the cooling temperature in the second stage freezing tank150, the output from the second stage freezing tank150may be composed primarily, or entirely, of frozen solids such that all the impurities are discharged in solid phase, or where the output consists of only a small stream of highly concentrated liquid discharge.

The ice, salt-hydrates and ICL from the second stage freezing tank150are separated in the same manner explained above with regard to the single stage systems depicted inFIGS.1-2, depending on the composition of the streams leaving the primary separator108. As depicted inFIG.3, the salt-brine-ICL slurry from the second stage freezing tank150is delivered to the primary separator108. In this embodiment, an ice-ICL slurry is discharged from the top of the primary separator108and provided to the ice-ICL separation module134as depicted in the embodimentFIG.2. The ice-ICL separation module134may include the ice-ICL separator136, which fees the first melting tank126and optional second melting tank128. The ice-ICL separator136separates (through cyclonic or other mechanical separation mechanism) the heavier ice crystals from the lighter ICL liquid. The ICL liquid is pumped back to the ICL tank114. In the variation depicted inFIG.3, the ice crystals sent directly to the first melting tank126without the use of a conveyor belt. It will be appreciated that the conveyor belt124, wash array130and catch basin132can also be incorporated into the embodiment depicted inFIG.3.

The salt-brine slurry produced by the primary separator108is passed to the salt-brine separation module138, which includes the salt-brine separator140. The salt brine separator140can be configured as a cyclonic separator that separates the lighter brine fluids from the heavier salt crystals. The lighter brine fluids are passed to the brine feed line back to the second stage freezing tank150, while the solid salt crystals are discharged for disposal or downstream processing. Although the output from the primary separator108depicted inFIG.3follows the basic processing path depicted inFIG.2, it will be appreciated that in some applications, the output from the primary separator108follows the processing steps depicted inFIG.1such that that an ice-brine slurry is discharged to a water brine separation module110and the ICL-brine mixture is directed to an ICL-brine separation module112.

The two-stage freeze process is particularly advantageous for relatively lower brine concentrations (TDS<200,000 ppm). Above 200,000 ppm, there may be smaller differences between the energy efficiency of the single-stage and two-stage designs, mainly because no significant freezing occurs at temperatures above −20 C for such high concentration brines.

Turning toFIG.4, shown therein is a process flow diagram for a freeze desalination method200. The method200presents a general description of the processes that can be practiced using the systems depicted inFIGS.1-3. It will be appreciated that the method200presents an overview of the desalination methods and many of the individual steps have been omitted from the diagram presented inFIG.4.

Beginning at step202, the feed brine102is provided to the water treatment system100. At step204, the intermediate-cold-liquid (ICL) is cooled to provide the refrigerated ICL source104. At step206, the feed brine102is contacted with the refrigerated ICL in a freezing or crystallization tank106for a time sufficient and under appropriate conditions to form ice crystals within the tank. Next, at step208, the ice crystals are separated from the ICL and brine. In certain applications, the interaction between the brine and the ICL may have formed hydrohalites, which are also separated from the ice crystals.

At step210, the ICL is separated from the other constituent components and returned to the refrigerated ICL source104. The ICL can be separated from the other components through an ICL-brine separation module112or an ice-ICL separation module134. At step212, the solid salt crystals are separated from the brine. The salt can be separated from the brine with the salt-brine separator120,140. The solid salt can be discarded or used in downstream processes. At step214, the remaining brine is returned for further processing in the main crystallization tank106(in a single stage process), or to the first stage freezing tank142(in a two stage process).

At step216, the separated ice crystals a melted to form desalinated liquid water. The melting process can take place through use of the first melting tank126alone, or in combination with the second melting tank128, wash array130and catch basin132. It will be appreciated that in certain embodiments, the separated ice crystals can simply be transferred to a storage container or facility to be held at freezing temperatures, or at temperatures that allow the ice to melt over time to form desalinated water.

Thus, the embodiments of the present disclosure are well adapted to carry out the objects and attain the ends and advantages mentioned above as well as those inherent therein. While the inventive system and method have been described and illustrated herein by reference to particular non-limiting embodiments in relation to the drawings attached thereto, various changes and further modifications, apart from those shown or suggested herein, may be made therein by those of ordinary skill in the art, without departing from the spirit of the inventive concepts