WO2018138643A1

WO2018138643A1 - Process and system for separating inorganic component from liquid

Info

Publication number: WO2018138643A1
Application number: PCT/IB2018/050420
Authority: WO
Inventors: Rakesh Kumar; Supriya APEGAONKAR; Sasanka RAHA; Ramesh BHUJADE
Original assignee: Reliance Industries Limited
Priority date: 2017-01-28
Filing date: 2018-01-24
Publication date: 2018-08-02

Abstract

The present invention relates to the field of purification technology. The present disclosure relates to a simple, economical and effective multi-stage process for purifying liquid using a multi-stage system capable of providing differential temperature and pressure conditions. In particular, the present disclosure relates to a process and a system for separating soluble inorganic component from water under supercritical conditions to obtain purified water wherein said process is performed using a system comprising multi-stage separator assembly along with one or more flash separators, and wherein differential temperature and pressure conditions are provided within each separator and between the separators. Said process addresses limitations of existing desalination processes such as, membrane processes and thermal technology processes which require features including but not limiting to high energy, high maintenance cost and frequent flushing of the system.

Description

PROCESS AND SYSTEM FOR SEPARATING INORGANIC COMPONENT FROM

LIQUID

TECHNICAL FIELD

The present disclosure relates to the field of purification technology. The present disclosure relates to a simple, economical and effective multi-stage process and a system for purifying liquid, preferably water by separating soluble inorganic component from said liquid using differential temperature and pressure conditions. BACKGROUND AND PRIOR ART OF THE DISCLOSURE

Liquids such as water contains many soluble inorganic salts including NaCl, MgCh, CaCl₂.2H₂0, KC1, Na₂S0₄, (NH₄)₂S0₄, FeCb, ZnCh, K₂S0₄, Na₂C0₃, Na₃P0₄ and combinations thereof. Consumption of such salts in the recommended quantities (through water) is although essential for routine biological processes of animals and plants, but overconsumption of the same lead to detrimental effects affecting the biological system. For instance, consumption of sodium chloride at high concentrations increases the blood volume, blood pressure which will lead to edema, or swelling in various parts of the human body and heart-attack or stroke. Further, researchers have demonstrated that higher intake of sodium salt increases the possibility of occurrence of stomach cancer, osteoporosis and increases the risk of cognitive decline. Similarly, it has been demonstrated that excess administration of ZnCh affects the haematological parameters in rock pigeon. Also, higher concentrations of salts in water alters the physicochemical properties of water affecting various chemical and biochemical processes of plants and animals, and organoleptic properties affecting the palatability of food or water itself. Thus, it is imperative to reduce the concentration of salts in water to obtain purified water.

Several processes have been developed in the past for removing soluble inorganic salts from water. For example, desalination processes by membrane separation and thermal evaporation have been employed. Membrane desalination is based on the concept of semi- permeable membrane that permits passage of selective ions. Well-known processes based on membrane separation are reverse osmosis (RO), ultra-filtration, nano filtration, electro-dialysis (ED) and electrodialysis reversal (EDR). Different driving forces are used for membrane desalination, such as pressure, electrical potential and concentration gradient. For instance, in RO treatment, system pressure is used to remove salt components from saline feed stream. RO membranes are designed to retain salt components while allowing water to pass though the membrane. RO membranes are made of cellulose acetate, polyamide and other polymeric materials. However, major disadvantages of the membrane processes are that they require high energy and maintenance cost. For example, RO treatment requires frequent flushing of the system as efficiency of the process decreases over a period of operation.

In thermal desalination, water is evaporated from saline water and vapor is condensed to get distilled water. Major processes based on this category are multi stage flash (MSF) distillation, multiple effect distillation (MED) and vapor compression. In MSF distillation, water is heated in a series of stages. Pressure and temperature decreases in the successive stages of operation. Vapor is generated by reducing the pressure in different stages called as flashing. Flashing of a portion of feed mixture takes place in each successive stage at lower pressure. However, major drawbacks in thermal technologies are high energy requirement during vaporization step and low fresh water to feed ratio (50%) for sea water application

Although removal of salts from water have existed both in commercial practice and at the research level, these methods have limitations, such as, membrane processes require high energy and maintenance cost, whereas RO treatment requires frequent flushing of the system as efficiency of the process decreases over a period of operation. For sea water as a feed, RO process gives low fresh water to feed water ratio in the range of 35-50% due to higher osmotic pressure. Thus, there is a need for better, efficient and simpler process for removal of soluble inorganic component/salts from liquids, more particularly water to obtain purified water. The present disclosure aims at overcoming the drawbacks of prior art to provide an improved, effective, economical and scalable process for removal of soluble inorganic component from liquids.

STATEMENT OF THE DISCLOSURE

The present disclosure relates to a process for separating soluble inorganic component from liquid feed stock, said process comprising steps of:

a) treating the liquid feed stock to separate inorganic component under differential temperature and pressure conditions to obtain a lean mixture of inorganic component containing fluid and a rich mixture of inorganic component containing fluid, and b) repeating step (a) with the lean mixture of inorganic component containing fluid to further separate inorganic component from the lean mixture of inorganic component containing fluid; and a system (100) for separating soluble inorganic component from liquid feed-stock, the system (100) comprising:

a pump (2) to pressurize stream ( 1) of liquid feed-stock comprising inorganic component (s), above a predetermined pressure, a multi-stage separator assembly (101) comprising a plurality of separators (6,8, 27), wherein one of the plurality of separators (6,8, 27) is fluidly connected to the pump (2), for receiving a pressurized stream (3) of liquid comprising inorganic component from the pump (2), wherein, at least a portion of each of the plurality of separators (6,8, 27) is maintainable at a temperature higher than a remaining portion of respective separator of the plurality of separators (6,8, 27) to obtain a lean mixture of soluble inorganic component containing fluid and a rich mixture of inorganic component containing fluid.

BRIEF DESCRIPTION OF ACCOMPANYING FIGURES FIG. 1 illustrates schematic view of a system for separating soluble inorganic components from liquid with two separators in a multi-stage separator assembly, according to an exemplary embodiment of the disclosure.

FIG. 2 illustrates schematic view of a system for separating soluble inorganic component from liquid with three separators in a multi-stage separator assembly, according to an exemplary embodiment of the disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

The present disclosure is addressed to the aforementioned needs of the art and provides an improved and simple process for removal of soluble inorganic component from liquid.

In an embodiment of the disclosure, the process for removal of soluble inorganic component from liquid is carried out under supercritical conditions using a multi-stage separator assembly. As used herein, the terms "separator" or "salt separator" are employed interchangeably within the instant disclosure.

The disclosure relates to a multi-stage process process for separating soluble inorganic component from liquid feed stock, said process comprising steps of:

a) treating the liquid feed stock to separate inorganic component under differential temperature and pressure conditions to obtain a lean mixture of inorganic component containing fluid and a rich mixture of inorganic component containing fluid; and b) repeating step (a) with the lean mixture of inorganic component containing fluid to further separate inorganic component from the lean mixture of inorganic component containing fluid.

In an embodiment of the disclosure, the above process is carried out in a multistage separator assembly comprising a plurality of separators.

In another embodiment of the disclosure, the step (a) of the above process is carried out in a first separator of the plurality of separators wherein at least a portion of the first separator is maintained at a temperature higher than the remaining portion of the first separator. In yet another embodiment of the disclosure, the repetition in step (b) is about one time to four times, and wherein each repetition in the step (b) is carried out in at least one of remaining separators of the plurality of separators.

In still another embodiment of the disclosure, the repetition in step (b) is about one time to two times, and wherein each repetition is carried out in at least one of remaining separators of the plurality of separators.

In still another embodiment of the disclosure, at least a portion of each of the aforesaid remaining separators of the plurality of separators is maintained at a temperature higher from a remaining portion of the respective separator of the plurality of separators.

In still another embodiment of the disclosure, the first repetition of the above step (b) is carried out in a second separator of the plurality of separators. In still another embodiment of the disclosure, the second repetition of the above step (b) is carried out in a third separator of the plurality of separators.

In still another embodiment of the disclosure, the highest temperature in any separator of the multistage separator assembly ranges from about 300 °C to 700 °C and pressure ranges from about 200 bar to 500 bar.

In still another embodiment of the disclosure, the lean mixture of inorganic component containing fluid is obtained in at least a portion of each of plurality of separators maintained at higher temperature and the rich mixture of inorganic component containing fluid is obtained in a remaining portion of each of plurality of separators maintained at a lower temperature.

In still another embodiment of the disclosure, the temperature in each separator of the plurality of separators varies and wherein the minimum temperature difference between the two successive separators is 1 °C.

The present process of separating soluble inorganic component from liquid feed stock is a multi-stage process carried out in a multistage separator assembly comprising a plurality of separators.

In an embodiment of the disclosure, said multi-stage process includes but not limited to a two stage process or a three stage process.

In another embodiment of the disclosure, the two-stage process is carried out in a two-stage separator assembly comprising two separators.

In yet another embodiment of the disclosure, the three-stage process is carried out in a three- stage separator assembly comprising three separators. In an exemplary embodiment of the disclosure, the two-stage process of separating soluble inorganic component from liquid feed stock comprises steps of:

a) treating the liquid feed stock to separate inorganic component in a first salt separator under differential temperature and pressure conditions to obtain a lean mixture of inorganic component containing fluid (a lean mixture- 1) and a rich mixture of inorganic component containing fluid (a rich mixture 1); and

b) treating the lean mixture- 1 of step (a) in a second salt separator under differential temperature and pressure conditions to further separate inorganic component from the lean mixture- 1 and obtain a lean mixture of inorganic component containing fluid (a lean mixture -2) and a rich mixture of inorganic component containing fluid (a rich mixture -2).

In another exemplary embodiment of the disclosure, the three-stage process of separating soluble inorganic component from liquid feed stock comprises steps of:

a) treating the liquid feed stock to separate inorganic component in a first salt separator under differential temperature and pressure conditions to obtain a lean mixture of inorganic component containing fluid (a lean mixture- 1) and a rich mixture of inorganic component containing fluid (a rich mixture-1); and

b) treating the lean mixture-1 of step (a) in a second salt separator under differential temperature and pressure conditions to further separate inorganic component from the lean mixture-1 and obtain a lean mixture of inorganic component containing fluid (a lean mixture -2) and a rich mixture of inorganic component containing fluid (a rich mixture -2); and

c) treating the lean mixture-2 of step (b) in a third salt separator to further separate inorganic component from the lean mixture-2 and obtain a lean mixture of inorganic component containing fluid (a lean mixture-3) and a rich mixture of inorganic component containing fluid (a rich mixture-3).

In an embodiment of the disclosure, a portion of any salt separator in the multi-stage process is subjected to higher temperature and the remaining portion of salt separator is subjected to lower temperature.

In an embodiment of the process, the number of stages (2-stage, 3-stage, 4-stage etc.) in the multistage process depends on the type of liquid feedstock used in the process wherein the final liquid obtained at the end of the process should contain less than 600 ppm of soluble inorganic component. In another embodiment of the disclosure, a portion of any salt separator in the two-stage or three-stage process is subjected to higher temperature and the remaining portion of salt separator is subjected to lower temperature.

In the multi-stage process of the present disclosure, the lean mixture produced in the consecutive salt separator(s) is relatively leaner or comprises lesser amount of soluble inorganic component than the lean mixture produced in the foregoing salt separator(s).

In an embodiment of the disclosure, the lean mixture-2 produced in the second salt separator is relatively leaner or comprises lesser amount of soluble inorganic component than the lean mixture- 1 produced in the first salt separator. In another embodiment of the disclosure, the lean mixture-3 produced in the third salt separator is relatively leaner or comprises lesser amount of soluble inorganic component than the lean mixture-2 and the lean mixture- 1 produced in the second salt separator and the first salt separator respectively.

In still another embodiment of the disclosure, the rich mixture of inorganic component containing fluid is subjected to flash separation to obtain inorganic component.

In the multi-stage process of the present disclosure, the lean mixture in each salt separator(s) comprises lesser amount of soluble inorganic component than the rich mixture of the respective salt separator(s).

In an embodiment of the disclosure, the concentration gradient between rich mixture of inorganic component containing fluid and lean mixture of inorganic component containing fluid is at least 10 ppm with respect to inorganic component. In another embodiment of the disclosure, the concentration gradient between rich mixture of inorganic component containing fluid and lean mixture of inorganic component containing fluid is at least 10 ppm with respect to inorganic component with in the each separator of the separation process of multi-stage separator process. In an embodiment of the disclosure, the concentration gradient between rich mixture of inorganic component containing fluid (rich mixture- 1) and lean mixture of inorganic component containing fluid (lean mixture- 1) is at least 10 ppm with respect to inorganic component with in the each separator of the separation process of two-stage separator process.

In another embodiment of the disclosure, the concentration gradient between rich mixture of inorganic component containing fluid (rich mixture-2) and lean mixture of inorganic component containing fluid (lean mixture-2) is at least 10 ppm with respect to inorganic component with in the each separator of the separation process of two-stage separator process.

In an embodiment of the disclosure, the concentration gradient between rich mixture of inorganic component containing fluid (rich mixture- 1) and lean mixture of inorganic component containing fluid (lean mixture- 1) is at least 10 ppm with respect to inorganic component with in the each separator of the separation process of three-stage separator process.

In another embodiment of the disclosure, the concentration gradient between rich mixture of inorganic component containing fluid (rich mixture-2) and lean mixture of inorganic component containing fluid (lean mixture-2) is at least 10 ppm with respect to inorganic component with in the each separator of the separation process of three-stage separator process.

In another embodiment of the disclosure, the concentration gradient between rich mixture of inorganic component containing fluid (rich mixture-3) and lean mixture of inorganic component containing fluid (lean mixture-3) is at least 10 ppm with respect to inorganic component with in the each separator of the separation process of three-stage separator process.

In an embodiment of the disclosure, the process purifies the liquid feedstock comprising inorganic component, and wherein the purified liquid comprises inorganic component below 600 ppm.

In an embodiment of the disclosure, the liquid is water.

In another embodiment of the disclosure, the liquid is sea water or waste water.

In an embodiment of the disclosure, the inorganic component is inorganic salt, preferably soluble inorganic salt selected from a group comprising MgCh, CaCh.2H20, KC1, NaCl, NaiSC , (NH₄)₂S04, FeC , ZnCh, K2SO4, Na₂C0₃, Na₃P0₄ and combinations thereof. In another embodiment of the disclosure, the process is a desalination process and the process aids in removal of salts from liquid.

In an embodiment of the disclosure, the plurality of the salt separators are connected to plurality of flash separators.

In another embodiment of the disclosure, the each separator of the plurality of the salt separators is connected to one flash separator of plurality of flash separators In yet another embodiment of the disclosure, the plurality of the salt separators and flash separators ranges from 2 to 100.

In still another embodiment of the disclosure, the plurality of the salt separator and flash separator used in the process depends on the initial salt concentration of the feed-stream water.

Water exhibits distinct thermal and physical properties that changes drastically when temperature and pressure conditions employed under supercritical condition (T=374 °C, P= 221 bar). Near supercritical conditions, density of water decreases with temperature and pressure and liquid behaves like vapor. Under supercritical condition, liquid and vapor phases remain indistinguishable and shows drastic changes in thermodynamic and physical property of water. For example, dielectric constant of water has very high value (80 at 25 °C) due to strong hydrogen bonding. When temperature and pressure approaches supercritical condition, hydrogen bonding becomes weak and dielectric constant decreases nearly to 2.0 at 450 °C and 300 bar. Reduction in dielectric constant leads to decrease in dissolving capacity of water. Also, water behaves like nonpolar component and leads to increase in solubility of organic molecules. At higher temperature and pressure conditions, electrolytes become weak electrolyte and behave like nonpolar component. Nonpolar nature of super-critical water at higher temperature and pressure decreases salt solubility that leads to precipitation of salts. In an exemplary embodiment of the disclosure, water or waste water enriched with inorganic components including but not limited to CaS04, NaCl, Na2S04, KC1, MgCh at any concentration (up to 30 wt%) are subjected to high temperature (300 °C or above) and high pressure (200 bar or above) conditions in separator to reduce concentration of inorganics in purified water. In the separator, reduction in solubility of components takes place under sub/super-critical conditions. Temperature differences in different zones of separator are maintained for continuous withdrawal of lean and rich water streams of inorganic components. Separator equipment has no moving part and doesn't require significant maintenance cost, unlike conventional membrane or RO processes.

Waste water/sea water contains different type of soluble inorganics mixture. Phase behaviour of binary salt mixture may be classified into two main categories, i.e. type 1 and type 2 phase behaviour. At higher temperature (above 300 °C) and pressure (above 200 bar), type 1 components (such as but not limited to NaCl) form a liquid and vapour mixture and type 2 components (such as but not limited to NaiSCU) form supercritical fluid and inorganics phase. Different soluble inorganics (such as but not limited to CaS04, NaiSC and NaCl) show difference in solubility limit at higher temperature (above 300 °C) and higher pressure (above 200 bar). In order to remove specific inorganic component or their mixtures more efficiently from impure water stream, the present process exposes feed water at different temperature and pressure conditions. Further, it is difficult to obtain substantial separation of the mixture of inorganic components (to produce processed/potable water) in a single stage separator due to non-ideal behaviour of the system under high temperature and pressure condition. Solubility of salts in different phases of separator may not reach thermodynamic equilibrium condition under the operating temperature, pressure and hydrodynamic conditions of separator. Enhancement in inorganic soluble components separation efficiency is achieved by exposing impure water stream in multi-stage separator where partially treated product stream from early stage is further treated in next stage of separator. Present invention provides such a process for separation of specific soluble inorganic or mixture of soluble components present in the sea/waste water at different temperature and pressure in multiple stages using multiple separators. In one embodiment of the disclosure, each of the separators are operated above 300 °C and 200 bar pressure to produce potable water to obtain inorganic salt components concentration of less than 600 ppm in the final water stream. Treating impure water with mixture of components in multi-stage separator (different temperature and pressure conditions in different stages) leads to reduction in the specific component(s) in different stages and thus obtain pure potable/process water to the desired purity level in the product stream. Additionally, the separated specific salts/inorganic components are recovered that can be refined after further treatment and produced as by-product from the purification plant. As separator operation requires higher temperature and pressure conditions, energy present in the product streams are recovered by rigorous process energy integration. Additionally, the inorganic components are recovered as a by-product in the process.

The present disclosure also provides a multi-stage system for separating soluble inorganic components from liquid such as water. The system is configured to purify the water from inorganic components in multiple stages to obtain purified water with less than 600 ppm of inorganic components in the water.

The system for separating inorganic components from liquid comprises a pump which receives stream of a liquid-feedstock and pressurise the stream above a predetermined pressure . A multistage separator assembly comprising a plurality of separators are configured in the system for separating the in-organic components from the liquid feed-stock. One of the plurality of separators is fluidly connected to the pump and receives a pressurised stream of liquid comprising inorganic component from the pump. For separating the inorganic components from the liquid, each of the plurality of separators are maintainable at variable temperatures. Wherein, at least a portion of each of the plurality of separators is maintainable at a temperature higher than a remaining portion of respective separator of the plurality of separators. This results in separation of a lean mixture of inorganic component containing fluid and a rich mixture of inorganic component containing fluid in the separators. The rich mixture of inorganic component containing fluid flows to the low temperature region of the corresponding separator, and the lean mixture of inorganic component containing fluid will remain in high temperature region of the corresponding separator. The lean mixture of inorganic component containing fluid obtained from each separator is subjected to further purification in subsequent stage of separator to separate the inorganic components from the liquid.

The system of the disclosure comprises one or more flash separators fluidly connected to the plurality of separators. The one or more flash separators are configured to receive the rich mixture of inorganic component containing fluid from the plurality of separators, and separate concentrated inorganic component and steam. The steam separated in in the one or more flash separators is supplied to one or more prime movers to generate a power, wherein the one or more prime-movers are coupled to the pump for supplying the power. In an embodiment, the one or more flash separators and turbines are optional aspects of the system.

The system also comprises an arrangement for heat integration which aid in separation of the in-organic components from the liquid. The arrangement for heat integration comprises a heat source coupled one or more separator of the plurality of separators. In an embodiment of the disclosure, the heat source is an electric heating element, configured to heat the corresponding separator to a predetermined temperature. The arrangement also a heat exchanger coupled to one or more separators of the plurality of separators. The heat exchanger is configured to receive heat from at least one of the lean mixture of in-organic component flowing out of the one or more separators and supply heat to adjacent separator. Further, the system includes a cooling source coupled to the remaining portion of each separator of the plurality of separators. The cooling source is configured to receive a coolant and extract the heat from the remaining portion of the corresponding separator for maintaining the remaining portion at lower temperature when compared to the at least a portion of the separator.

The following paragraphs describe the present disclosure with reference to FIGS. 1 and 2. In the figures the same element or elements which have same functions are indicated by the same reference signs. In the description, the words such upward, downward, above, below, adjacent are used with respect to particular orientation of the system as illustrated in the figures. However, such terminologies may be variable as per the change in orientation of the figures.

Referring now to the FIG. 1, which is an exemplary embodiment of the present disclosure illustrating a system (100) for separating soluble in-organic components from the liquid using two stage separator assembly (101). The system ( 100) comprises a pump (2) to pressurise a stream of liquid containing inorganic components and supply to the multi-stage separator assembly (101) for purification. The multi-stage separator assembly (101) comprises a first separator (6) fluidly connected to a pump (2), and a second separator (8) fluidly connected to a first separator (6). The first separator (6) is configured such that at least a portion (6a) of the first separator (6) is maintainable at a temperature higher than a remaining portion (6b) of the first separator (6). Also, the second separator (8) is configured such that at least a portion (8a) of the second separator (8) is maintainable at a temperature higher than a remaining portion (8b) of the second separator (8). The system (100) may optionally comprises a plurality of flash separators ( 15 and 19) fluidly connected to the first and second separators (6 and 8), and at least one turbine (22 and 24) fluidly connected to the plurality of flash separators ( 15 and 19).

The system (100) also includes an arrangement for heat integration. The arrangement for heat integration comprises a heater (7) coupled to the second separator (8), heat exchanger coupled to the first separator and cooling source [not shown] coupled to the remaining portions (6b and 8b) of the first and second separators (6 and 8) respectively. The operation of the system (100) for separating soluble inorganic components from the liquid feed stock such as water is described as follows. Water stream (1) containing inorganic components such as but not limiting to CaS04, NaCl, KC1, Na2S04 etc. is pressurized above predetermined pressure, for example above 200 bar, through a pump (2) and fed to the first separator (6) from ambient to sub-critical condition (300°C). In an embodiment, the pump (2) feeds the pressurised water containing inorganic components through top of the first separator (6). In an alternate embodiment, the feed can also be introduced from alternate locations for example bottom, side of first separator (6) at different orientations. A treated water stream also referred as purified water stream (11) from a second separator (8) may be used to supply heat to the first separator (6) through the heat exchanger [not shown] for operation. The first separator (6) is heated up-to to the desired temperature for example above 300°C during operation. In an embodiment of the disclosure, the first separator (6) is a cylindrical vessel of any orientation (vertical or slanted) designed for high temperature and high pressure standards. The cylindrical vessel may be made from a material including Inconel, Hastelloy, Titanium etc. or any other suitable material as appropriate.

The system (100) is configured such that any stage of multi-stage separator assembly (101) contains different thermal zones where different temperature conditions are maintained. In an embodiment, about 2/3 rd section referred as at least a portion (6a) from top of the first separator (6) is maintained at high temperature and pressure conditions for example above 300°C and 200 bar, and about l/3rd section refereed as remaining portion (6b) of the first separator (6) from bottom is maintained at lower temperature than that maintained in upper section by using appropriate external coolant for resolubilization of inorganic components. In higher temperature zone or at least a portion (6a) of the first separator (6), fluid temperature is maintained between 300°C -700°C at pressure of 200-500 bar. Higher temperature conditions in the at least a portion (6a) of first separator (6) leads to reduction in solubility of soluble inorganic components. After separation, denser fluid components flows down to lower temperature zone i.e. remaining portion (6b) of the first separator (6) and get resolublized or diluted, and a stream (5) involving concentrated inorganic component is withdrawn continuously as bottom stream from the first separator (6). Also, inorganic component lean stream is withdrawn as top product stream (4) from the first separator (6). In an embodiment, streams (4 and 5) can also be withdrawn from any location of first separator (6) such as top, bottom or middle at any desired orientation. A further treatment of top product stream i.e. inorganic component lean stream (4) is carried out in second separator (8) in a similar manner as of first separator (6), but at different temperature and pressure condition. The desired temperature in the second separator (8) for effective soluble inorganics removal is provided by external heating source (7). The inorganic component is withdrawn continuously as a bottom product in stream ( 10) of the second separator (8), and purified water stream ( 11 ) is withdrawn continuously from the top of the second separator (8).

In addition to water purification, inorganic components present in concentrated streams (5 and 10) are further concentrated by producing steam in the flash separators (15 and 19). The streams (5 and 10) comprising inorganic components and fluid are processed in the flash separators (15 and 19) respectively for producing steam (streams 13 and 17) and concentrated salt (streams 14 and 18). Further, streams (14 and 18) containing inorganic components may be treated further for salt recovery as by-products. In the system (100) of the present disclosure energy is recovered by exchanging of heat contained in stream purified water stream (1 1) flowing out of second separator (8) through the heat exchanger [not shown] . The recovered heat is supplied to the first separator (6). Also, pressure energy from streams (1 1 , 13 and 17) is recovered though energy recovery unit such as turbines (12 and 20). The turbines (12 and 20) coverts the kinetic energy of the steam in the streams (1 1, 13 and 17), and drives the pump (2). In an embodiment, the turbines (12 and 30) may be directly coupled to the pump (2) such that the mechanical energy required for driving the pump (2) may be supplied by the turbines ( 12 and 30). In an alternate embodiment, the energy produced by the turbines (12 and 30) is stored in a storage unit [not shown] such as battery and may be utilized for driving the pump (2).

In an embodiment of the disclosure, the first stage (6) and second stage (8) of the multi-stages of separator assembly (100) may be operated at different temperature and pressure and in some specific case at same temperature and pressure conditions to remove specific salt or mixture of salts to produce high purity water.

In order to achieve high purity of treated water in the product stream and separation of specific inorganic component more efficiently, impure water is processed through multi-stage salt separators (100), for example three stage separators as shown in FIG. 2.

Now referring to FIG. 2 which is another exemplary embodiment of the disclosure, illustrating a system (100) for separating soluble in-organic components from the liquid using three stage separator assembly (101). The system (100) as shown in FIG. 2 includes a third separator (27) in addition to the first separator (6) and second separator (8) of the multi-stage separator assembly (101). The third separator (27) is configured such that at least a portion (27a) of the third separator (6) is maintainable at a temperature higher than a remaining portion (27b) of the third separator (6). The system (100) of FIG. 2 also includes a flash separators (31) in addition to the flash separators (15 and 19). The flash separator (31) is fluidly connected to the third separators (27), and at least one turbine (22) is fluidly connected to the plurality of flash separators (31). The system (100) as shown in FIG. 2 also includes an arrangement for heat integration. The arrangement for heat integration comprises a heater (7) coupled to the third separator (8) and optionally to the second separator (8), heat exchanger coupled to the first separator (6) and optionally to the second separator (8) and cooling source [not shown] coupled to the remaining portions (6b, 8b, and 27b) of the first, second, and third separators (6 and 8) respectively.

The operation of the system ( 100) with three separators in the multi-stage separator assembly is described as follows. The operation of first two stages i.e. first separator (6) and the second separator (8) of the system (100) of FIG. 2 is same as the operation of the system (100) of FIG. 1. In addition, to the operations of the system ( 100) of FIG. 1 , the inorganic component lean stream (9) flowing out of the second separator (8) is further treated in the third separator (27). During the operations, the third separator (6) is heated up-to to the desired temperature using an external heat source (7). The third separator (27) is configured such that, about 2/3rd section referred as at least a portion (27a) from top of the third separator (27) is maintained at high temperature and pressure conditions, and about l/3rd section referred as remaining portion (27b) of the third separator (27) from bottom is maintained at lower temperature than that maintained in upper section by using appropriate external coolant for resolubilization of inorganic components. Higher temperature conditions in the at least a portion (27a) of third separator (27) leads to further reduction in solubility of soluble inorganic components. Now, denser fluid components flow down to lower temperature zone i.e. remaining portion (27b) of the third separator (27) and get resolublized or diluted. A stream (30) involving concentrated inorganic component is withdrawn continuously as bottom stream from the third separator (27). Also, the water free of inorganic component is withdrawn as top product stream (28) from the third separator (27). The streams (30) comprising inorganic components and fluid are processed in flash separator (31) respectively for producing steam (streams 32) and concentrated salt (streams 33). Further, stream (33) of inorganic components may be treated further for salt recovery as by-products. In the system (100) of the present disclosure energy is recovered by exchanging of heat contained in stream purified water stream (28) flowing out of the third separator (27) through the heat exchanger [not shown] . The recovered heat is supplied to the first separator (6) and the second separator (8). Also, pressure energy from streams (32) is recovered though energy recovery unit such as turbine (20). In an embodiment of the disclosure, the water free of inorganic component withdrawn as top product stream (28) from the third separator (27) will have less than 600ppm of inorganic components.

In an embodiment of the disclosure, the temperature and pressure in the multi-stage separator assembly (101) gradually reduces from the first separator (8) to the third separator (27).

In an embodiment of the disclosure, the fluid connection medium between various components or devices including pump, multi-stage separator assembly, flash separators, turbine, heat exchanger are hoses, pipes, or tubes.

It should be noted that the configuration of system as illustrated in figures are exemplary configuration and should not be considered as limitation to the present disclosure. One skilled in the art may develop system having any other configuration without deviating from scope of the disclosure. It is also to be noted that the multi-stage separator assembly may have any number of separators depending on the requirement.

Table 1 : List of Referral Numerals:

Reference number Description

100 System for separating inorganic components

101 Multi-stage separator assembly

1 Stream of water comprising inorganic components

2 Pump

3 Pressurised water comprising inorganic components

4 Stream of lean mixture of inorganic component flowing

out of first separator 5 and 36 Stream of concentrated inorganic components flowing

out of first separator

6 First separator

6a At least a portion of first separator

6b Remaining portion of first separator

7 Heating source

8 Second separator

8a At least a portion of second separator

8b Remaining portion of second separator

9 or 1 1 Stream of lean mixture of inorganic component flowing

out of second separator

10 and 16 Stream of concentrated inorganic components flowing

out of second separator

12 and 20 Power from turbines

13, 17, 32 Streams of steam from the flash separators

14, 18, 33 Streams of concentrated inorganic components from the

flash separators

15, 19, 31 Flash separators

22 and 24 Turbines

27 Third separator

27a At least a portion of third separator

27b Remaining portion of third separator

28 Purified water flowing out of third separator

30 Stream of concentrated inorganic components flowing

out of third separator

Additional embodiments and features of the present disclosure will be apparent to one of ordinary skill in art based upon description provided herein. The embodiments herein provide various features and advantageous details thereof in the description. Descriptions of well- known/conventional methods and techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples provided herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the following examples should not be construed as limiting the scope of the embodiments herein.

EXAMPLES EXAMPLE 1 :

A 1000 kg/hr of salt water containing 3.6 wt% salts [3.1 NaCl (i.e. 32400 ppm), and 0.5 wt% Na2S04 (i.e. 3600 ppm)] is pumped through high pressure pump at 300 bar. Further, pressurized stream 3 (Figure 1) is fed to top of first stage salt separator 6a at ambient temperature conditions. Product water stream 11 (from second stage salt separator) is used to raise the temperature of feed stream in high temperature zone of salt separator 6a (to 410 °C from ambient condition). High temperature (410 °C) and high pressure (300 bar) condition in upper zone of separator stage 1 leads to reduction in solubility of NaiSC . Denser fluid components flowed to lower zone of separator 6b where temperature is maintained under subcritical conditions (280 °C). Temperature difference in the top outlet stream 4 and bottom outlet stream 5 is maintained at 130 °C. It is critical to maintain a temperature difference in the outlet streams of separator for efficient removal of salts. The temperature and summary of results of various streams are given in Table 2. Top product stream 4 (900 kg/h), lean in Na2S04 (91 ppm) and NaCl concentration (3388 ppm) is processed further in the second salt separator 8 where further reduction in salt concentration of NaCl (290 ppm) and Na2S04 (1 ppm) take place in purified stream 11. External heating of feed stream to the second stage salt separator 8 is provided through the heater 7 to raise temperature from 410 °C to 460 °C. Temperature difference in the top outlet stream 11 and bottom outlet stream 10 is maintained at 180 °C. High temperature (460 °C) purified water stream 9 is further used to supply heat through heat exchange in stage 1 separator 6. NaCl and NaiSCU present in salt water feed get concentrated in bottom product streams of salt separator 6 and 8. The concentrated discharge of the separator 6b contains 292493 ppm of NaOH and 35057 ppm of NaiSC , and 8b contains 42746 ppm of NaOH and 1234 ppm of Na2S04. Concentrated brine solution is further processed in flash separators 15 and 19 where steam (streams 13 and 17) and concentrated salts (stream 14 and 18) are obtained. Energy present in the different product streams are further recovered through turbines. Table 2: Temperature, pressure, salt concentration and flow rate of different process streams

Table 2 illustrates the differential temperature and pressure conditions which are maintained in the system for efficient separation of soluble salts from water which is subjected to purification process. Further, this table shows the manner in which the salt concentrations are reduced in the treated water during the separation process gradually in a systematic and efficient manner. The above presented data evidently demonstrates that majority of inorganic impurities are removed from the feedstock stream by the first separator followed by further purification in the subsequent separator to obtain highly purified water containing less than 600 ppm of salts. Thus, the above experiment successfully demonstrates the multi-stage process for separating inorganic salts from sea water or waste water under differential temperature and pressure conditions to obtain purified water and concentrated inorganic salts separately.

The present disclosure in view of the above described illustrations and various embodiments, is thus able to overcome the various deficiencies of prior art and provide for separating inorganic component(s) from liquid feedstock to obtain purified liquid. Additional embodiments and features of the present disclosure will be apparent to one of ordinary skill in art based on the description provided herein. The embodiments herein provide various features and advantageous details thereof in the description. Descriptions of well- known/conventional methods and techniques are omitted so as to not unnecessarily obscure the embodiments herein.

The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments in this disclosure have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

Throughout this specification, the word "comprise", or variations such as "comprises" or "comprising" wherever used, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

The use of the expression "at least" or "at least one" suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.

Any discussion of documents, acts, materials, devices, articles and the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.

While considerable emphasis has been placed herein on the particular features of this disclosure, it will be appreciated that various modifications can be made, and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other modifications in the nature of the disclosure or the preferred embodiments will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.

Claims

We claim:

1. A multistage process for separating soluble inorganic component from liquid feed stock, said process comprising steps of:

a) treating the liquid feed stock to separate soluble inorganic component under different temperature and pressure conditions to obtain a lean mixture of inorganic component containing fluid and a rich mixture of inorganic component containing fluid; and

b) repeating step (a) with the lean mixture of inorganic component containing fluid to further separate soluble inorganic component from the lean mixture of inorganic component containing fluid.

2. The process as claimed in claim 1, wherein the process is carried out in a multistage separator assembly comprising a plurality of separators.

3. The process as claimed in claim 1, wherein the step (a) is carried out in a first separator of the plurality of separators wherein at least a portion of the first separator is maintained at a temperature higher from a remaining portion of the first separator.

4. The process as claimed in claim 1, wherein the repetition in step (b) is about one time to four times, preferably about one time to two times, and wherein each repetition in the step (b) is carried out in at least one of remaining separators of the plurality of separators.

5. The process as claimed in claim 4, wherein at least a portion of each of the remaining separators of the plurality of separators is maintained at a temperature higher from a remaining portion of the respective separator of the plurality of separators.

6. The process as claimed in claim 1 or claim 4, wherein the first repetition of the step (b) is carried out in a second separator of the plurality of separators.

7. The process as claimed in claim 1 or claim 4, wherein the second repetition of the step (b) is carried out in a third separator of the plurality of separators.

8. The process as claimed in claim 1 or claim 2, wherein the highest temperature in any separator ranges from about 300 °C to 700 °C and pressure ranges from about 200 bar to 500 bar.

9. The process as claimed in claim 1 or claim 2, wherein the lean mixture of inorganic component containing fluid is obtained in at least a portion of each of plurality of separators maintained at higher temperature and the rich mixture of inorganic component containing fluid is obtained in a remaining portion of each of plurality of separators maintained at a lower temperature.

10. The process as claimed in claim 2, wherein the temperature in each separator of the plurality of separators is different and wherein the minimum temperature difference between the two successive separators is 1 °C.

11. The process as claimed in claim 1, wherein the rich mixture of inorganic component containing fluid is subjected to flash separation to obtain inorganic component.

12. The process as claimed in claim 1, wherein the process purifies the liquid feedstock comprising inorganic component, and wherein the purified liquid comprises inorganic component below 600 ppm.

13. The process as claimed in claim 1, wherein the liquid of the liquid feedstock is water.

14. The process as claimed in claim 1, wherein the inorganic component is inorganic salt, preferably soluble inorganic salt selected from a group comprising MgCh, CaCh.2H20, KC1, NaCl, NaiS04,

FeCb, ZnCk, K2SO4, NaiCC , Na₃P0₄ and combinations thereof.

15. The process as claimed in claim 1, wherein the concentration gradient between the rich mixture of inorganic component containing fluid and the lean mixture of inorganic component containing fluid is at least 10 ppm with respect to the inorganic component.

16. A system (100) for separating soluble inorganic component from liquid feed-stock, the system (100) comprising:

a pump (2) to pressurize stream (1) of liquid feed-stock comprising inorganic component (s), above a predetermined pressure; a multi-stage separator assembly (101) comprising a plurality of separators (6,8, 27), wherein one of the plurality of separators (6,8, 27) is fluidly connected to the pump (2), for receiving a pressurized stream (3) of liquid comprising inorganic component from the pump (2); wherein, at least a portion of each of the plurality of separators (6,8, 27) is maintainable at a temperature higher than a remaining portion of respective separator of the plurality of separators (6,8, 27) to obtain a lean mixture of soluble inorganic component containing fluid and a rich mixture of inorganic component containing fluid.

17. The system as claimed in claim 16 comprises one or more flash separators (15, 19, 31) fluidly connected to the plurality of separators (6, 8, 27), wherein the one or more flash separators ( 15, 19, 31) are configured to receive the rich mixture of inorganic component containing fluid from the plurality of separators (6, 8, 27), and separate concentrated inorganic component and steam.

18. The system (100) as claimed in claim 16 further comprises one or more prime movers

(22, 24) configured to receive the steam separated in the one or more flash separators (15, 19, 31) to generate power.

19. The system (100) as claimed in claims 16 and 17, wherein one or more prime-movers (22, 24) are coupled to the pump (2) for supplying the power.

20. The system (100) as claimed in claim 16 comprises a heat source (7) coupled to at least one separator of the plurality of separators (6, 8, 27).

21. The system (100) as claimed in claim 16 comprises a cooling source coupled to the remaining portion of each separator of the plurality of separators (6, 8, 27).

22. The system (100) as claimed in claims 16 comprises:

heat-exchanger coupled to at least one separator of the plurality of separators, wherein the heat exchanger is configured to:

receive heat from at least one of the lean mixture of inorganic component containing fluid flowing out of the at least one separator; and supply heat to the adjacent separator of the at least one separator.

23. The system ( 100) as claimed in claim 16, wherein liquid of the liquid feedstock is water.