Title of Invention

"NOVEL LIQUID-SOLID RADIALLY CROSS FLOW MULTI STAGE FLUIDIZED BED CONTACTOR"

Abstract

The present disclosure provides a liquid solid multi-stage contactor for purification of a liquid by removal of undesirable dissolved solutes or recovery of desirable dissolved solutes. The contactor comprises a column consisting of at least three stages assembled together with flange joints. Each stage comprises a resin inlet, the purified liquid outlet at the top of the column, the resin outlet and the liquid inlet at the bottom of the column, a mesh fitted on a ring, where the ring is sandwiched between the flange joints on its either sides. The stages of the contactor comprises at least one downspout, where the downspout is a either central downspout located at the center of the stage or circumferential downspouts located at the periphery of the stage through which resin particles move from one stage to the next stage. The downspouts are located in the alternate stages. In this contactor the path length of the each fluidized solid moving across each stage is identical and therefore the mass transfer rate between liquid and solid on each stage is uniform. The utility of the liquid solid multi-stage contactor is, up to 90% of undesirable dissolved solids are removed or up to 90% of; desirable dissolved solids are recovered.

Full Text

FIELD OF INVENTION A liquid-solid multi-stage contactor useful for purification of effluents from industries such as fertilizer, nitric acid producing plants, agricultural lands, ores recovery plant and recovery of desirable dissolved solutes from biofluid such as blood. BACKGROUND OF INVENTION The utility of the stage wise counter current operation in chemical engineering separation processes has been substantially proven. In principle, the basic postulates of the counter current liquid-vapor operation envisaged in a distillation column may also be applied to the ion exchange and similar other L-S systems. In such case, the process is continuous and yields in higher separation efficiency of the solute relative to that obtained in a single stage fixed or fluidized bed operation. In such conventional contactors, the location of the downspout being eccentric the flow of the solid particles across the stage is non-uniform, with fraction of the solids short-circuiting from one side to the other side of the stage. The immediate impact of the maldistribution is on the non-uniform residence time distribution (RTD) of the solid particles causing reduction in the overall mass transfer rate. The United States patent number US429755 (1981) provides a process for absorbing ions of interest onto ion exchange resin particles from a feed liquor containing ions which when absorbed on said particles cause the density of the particles to increase. The process comprises the steps of (1) flowing the feed liquor upwardly through a main bed of ion exchange resin particles contained in a main chamber of an absorption column and thereby maintaining the bed in fluidized state; (2) continuously collecting the denser loaded particles from the lower region of the absorption column; (3) passing an outflow of the feed liquor from the upper region of the main chamber upwardly into the lower region of the polishing chamber containing a secondary bed of fluidized ion exchange resin particles whereby residual ions of interest are polished from the liquor, and (4) producing a barren liquor flowing out of the upper region of the polishing chamber. An article was also published by the present inventor N. Verma, Chem. Eng. Process, 45 (2006), 31-35, (and his another colleague K. Kishore) which provides mass transfer studies in multi-stage counter current fluidized bed ion exchangers. It is developed to study mass transfer during the continuous removal of dissolved anions from wastewater using commercially available resin. OH ion is used as an example in the study. A higher removal efficiency in the multi-stage fluidized bed than in a single-stage fixed and fluidized bed is demonstrated. The experiment shows progressive fluidization on a stage, smooth flow of resin across the stage and transfer of resin from one stage to the other. In each stage of the fabricated four-stage Perspex made column, a downspout has been provided to facilitate the downward flow of resin on to the next stage, while water flows counter currently upward through the mesh of the stage. The experimental variables in the multi-stage column operated under steady state includes the flow rates of water and resin, feed concentration, stage height and the number of stages. A mathematical model is also developed for determining the key parameters that affect the overall mass transfer in the multi-stage continuous counter current column. The Canadian Patent 980, 467 (1973) provides the multi-stage fluidized bed column for uranium recovery, wherein there are verticals stages containing resin and a single fluid inlet and pregnant feed solution passes in up-flow from stage to stage continuously, fluidizing the resin of a spouted bed, and the resin is transferred sequentially from stage to stage down the column using an auxiliary pump. The British Patent 1,070,251 (1967) provides the ion exchange or charcoal purification and decolorization of a sugar solution is performed by counter-currently contacting the solids with the solution in a process comprising alternate periods of solids, dispersion and substantially complete separation by settling, wherein solution moves through the system from one or more than one substantially wholly liquid-phase volume above the level of the dispersed solids, and solids move through the system from one or more than one substantially wholly solids-phase volume created by said settling. Particulate solids are counter currently contacted with a gas or liquid in a process comprising alternate periods of solids dispersion and substantially complete separation by settling, wherein fluid moves through the system from one or more substantially wholly fluids phase volume above the level of the dispersed solids, and solids move through the system from one or more substantially wholly solids phase volume created by said settling. The fluid flow may range from zero with maximum average solids flow to an average maximum corresponding to zero solids flow. The process may be applied to ion-exchange processes, e.g. for recovery of chromium and other metals from plating waste solutions, and of gold from leach solutions, to leaching coarse ground oxidized copper ore with sulphuric acid and to roasting pyrites minerals to produce sulphur dioxide. The reported literature for the stage-wise operation of the liquid-solid contactors is scant. Although there are commercial ion exchange units in operation since late 60s utilizing the principles of stage-wise operation in water softening and mineral processing, the technology is patented and the published data are inadequately informative. All of them primarily discuss the purification technique. SUMMARY OF THE INVENTION The present disclosure provides a liquid-solid multi-stage contactor for purification of a liquid by removal of undesirable dissolved solutes or recovery of desirable dissolved solutes. An embodiment of the present disclosure provides the liquid-solid multi-stage contactor for purification of a liquid by removal of undesirable dissolved solutes or recovery of desirable dissolved solute, (a) a column which had at least three stages assembled together with flange joints (b) a resin inlet at the top of the column (c) a mesh fitted on a ring, where the ring is sandwiched between the flange joints on its either sides and the liquid flows upward from one stage to the next stage through the mesh (d) at least one downcomer / downspout placed on the stages (d) an inlet at the bottom of the column through which the liquid is pumped up in the column (e) an outlet at the top of the column for obtaining a resultant purified liquid (f) an outlet at the bottom of the column for removal of the spent resin. The downcomer or downspout plays a typical role in the present invention. It is either central downspout located at the center of the stage or circumferential downspout located at the periphery of the stage through which resin particles move from one stage to the next stage. The central downspouts and the circumferential downspouts are located in the alternate stages, which helps smooth fluidization and movement over the stage, the uniform distribution of the solid particles across the stage. The contactor of the present disclosure provides for a wider range of operation without flooding and loading which is approximately 1.5 times the conventional range. A process for purification of a liquid by removal of undesirable dissolved solutes or recovering desirable dissolved solutes using liquid-solid multi-stage contactor, introducing a ion-exchange resin into said contactor from the top of the column, where said resin particles fill up each stages to a certain portion of the downspout height. Introducing liquid from the bottom of the column, where the flow rate of liquid is gradually increased up to the minimum fluidization condition resulting in the cross-flow of the fluidized resin particles on the stage while water flows upward through the voids between the resins to obtain liquid devoid of undesirable dissolved solutes or the desirable dissolved solutes.; The purification level obtained by using the liquid-solid multi-stage contactor of the present disclosure is up to 90%. BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS Fig la Schematic of three stage radial-flow fluidized bed. Fig Ib Schematic of solid-water radial flow fluidization. Fig 2a Schematic of the three stage conventional solid liquid contactor Fig 2b Comparison of flow patterns in two configurations DETAILED DESCRIPTION OF THE INVENTION The downspout is also referred to as a downcomer. The terms downspout and downcomer is used interchangeable hereinafter. The present disclosure provides a liquid-solid multi-stage contactor for purification of a liquid by removal of undesirable dissolved solutes or recovery of desirable dissolved solutes. An embodiment of the present disclosure provides the liquid-solid multi-stage contactor for purification of a liquid by removal of undesirable dissolved solutes or recovery of desirable dissolved solute, a column (made of Perspex with dimensions 300-500 mm H x 90-110 mm ID)) consisting of at least three stages (60-70 mm) assembled together with flange joints where each of the stages incorporates a resin inlet and resultant purified water outlet at the top of the column, a mesh with an openings (0.2-0.7 mm) made of brass fitted on a ring (aluminum), where the ring is sandwiched between the flange joints on its either sides, where the liquid flows upward from one stage to the next stage through the mesh. The unique feature of the contactor are, at least one downspout (downcomer) placed between the stages, wherein downspout is either central downspout located at the center of the stage or circumferential downspout located around the periphery of the stage through which resin particles move from one stage to the next stage. The central downspout or the circumferential downspout a*e is located in the alternate stages. There is an inlet at the bottom of the column through which the liquid is pumped upwards in the column and an outlet, nearby the said inlet for the spent resin. Another embodiment of the present disclosure provides the liquid-solid multi-stage contactor for purification of a liquid by removal of undesirable dissolved solutes where the liquid is selected from a group consisting of waste water such as effluents from industries such as fertilizer, nitric acid producing plants, or from agricultural lands, waste water slurry, ores recovery plant, etc. Yet another embodiment of the present disclosure provides the liquid-solid multi-stage contactor for recovery of desirable dissolved solutes from liquids such as biofluids like blood. Still another embodiment of the present disclosure provides the contactor wherein the dissolved solute is selected from a group consisting of arsenic ions, proteins, nitrogenous ions, solid sources of nutrients, fluoride ions and metal ions. A process for purification of a liquid by removal of undesirable dissolved solutes or recovering desirable dissolved solutes using liquid-solid multi-stage contactor, introducing a ion-exchange resin into said contactor from the top of the column, where said resin particles fill up each stages to a certain portion of the downspout height. Introducing liquid from the bottom of the column, where the flow rate of liquid is gradually increased up to the minimum fluidization condition resulting in the cross-flow of the fluidized resin particles on the stage while water flows upward through the voids between the resins to obtain liquid devoid of undesirable dissolved solutes or the desirable dissolved solutes.; The purification level obtained by using the liquid-solid multi-stage contactor of the present disclosure is up to 90%. The present disclosure provides the data pertaining to mass transfer studies carried out on four-stage Perspex made column and showed that up to 90% reduction in the dissolved solute concentrations may be achieved relative to the inlet concentration during a typical continuous operation. Fig la provides the arrangement of the novel contactor downspouts. The central downspout or the circumferential downspouts are arranged alternatively in each stage of the column. Further Fig la provides the movement of the resin through the central downspouts. Fig Ib provides a schematic representation of solid-water radial flow fluidization provides movement of the resin inlet at the top of the column while the water is pumped up from the inlet at the bottom of the column. Further, the figure shows the height of the downspout. Further, the figure shows the movement of resin from the circumferential downspout. Further, the figure shows the movement of resin through central/ circumferential downspout. Fig 2a provides a configuration of a three stage conventional solid liquid contactor with the arrangement of a single downspout per stage where each downspout is positioned at the opposite peripheral sides of the subsequent stages. Fig 2b provides a comparative diagrammatic representation of a three stage conventional solid liquid contactor and the flow of the conventional contactor vis-a-vis the contactor of the present disclosure. In all the above mentioned figures the configuration of the staged liquid-solid ion exchange column is similar to that of the sieve-trays distillation column used for vapour-liquid contacts, with fluidized resin particles flowing across the stage and moving to the subsequent stage through a downspout provided near the periphery of the column, while water flowing counter currently upward through the mesh of the stage [Refer to Fig lb]. Therefore in such conventional contactors, the location of the downspout being eccentric the flow of the solid particles across the stage is non-uniform, with fraction of the solids short-circuiting from one side to the other side of the stage [Refer to Fig 2a], The immediate impact of the mal-distribution is on the non-uniform residence time distribution (RTD) of the solid particles causing reduction in the overall the mass transfer rate. The present invention overcomes this effect. Figure la provides a schematic diagram of the designed and fabricated multi-staged fluidized bed column model of the present disclosure. The Perspex made column essentially consists of three stages (60-70 mm height per stage) assembled together with flange joints. A mesh with openings smaller than the particle size is fitted onto a ring sandwiched between every pair of adjoining flanges. The solid fluidized resin (INDION 220 catiaon exchanger) are fed from the top, while effluent water, is pumped from the bottom. The solid resin particles move across the stage on to the next stage through a downspout (or downcomer), as water flows upward through the mesh openings. There are two types of downspouts, which are fitted alternatively in the center and the periphery of the column walls. The one fitted at the center of a stage is the central downcomer and the other fitted at the outer periphery of the stage is the circumferential downcomer. The fluidized solids on each stage flow across radially inward or outward to the next downspout. In principal, the required bed height is determined from the mass transfer consideration and should be equal to mass transfer zone (MTZ). Counter current operation of solid-water flow permits achieving the required mass transfer rate within a small height. In the existing arrangement, the resin bed heights could be varied between 5 and 20 mm. Figure Ib is the schematic representation of flow conditions progressively existing on the stage, beginning with a fixed bed of resin particle with water flowing upward and then gradually changing over to the continuous operation in the column with water and resin flowing counter-currently at constant flow rates. To begin with, the resin particles may fill up the bed only to a certain fraction of the downcomer height, the bed height being slightly smaller than the downcomer height (h It would be judicious to compare the configuration in the present invention to that in the conventional design. Figure 2a describes the configuration of the conventional solid-liquid contactors, which are similar to that of a distillation column, with the movement of the solids from one side of the column to the other. Referring Figure 2b, fraction of the solid particles has longer paths than the remaining particles, with significant regions of solids under nearly stagnant conditions. The improvements claimed in the present invention are (1) uniform distribution of the solid particles across the stage, (2) smooth fluidization and movement over the stage, (3) wider range of operation without flooding and loading (approximately 1.5 times the conventional range), (4) less pressure-drop (30% smaller), and (5) few number of stages (30% smaller) with higher mass transfer rate between solid and liquid phase. The disclosure may be applied (but not limited to) in the following liquid solid contactor such as (a) Removal of recalcitrant solutes such as arsenic ions from industrial waste water effluents using ion exchangers, (b) Recovery of protein from biofluids using solid adsorbents, (c) De-nitrification of liquid enriched with nitrogenous ions using solid resin particles, (d) Enrichment of drinking water with nutrients using solid sources of nutrients, (e) Adsorption of fluoride ions from waste water by solid zeolite particles, (f) The recovery of precious metals from the slurry mixture. The present disclosure in example 1 provides the construction of the embodiment with the details. The present disclosure in example 2 provides the effect of resin flow rate and number of stages on effluent concentration in four stage column. EXAMPLES The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and the description of how to make and use the present invention, and are not intended to limit the scope of what the inventors regard as there invention nor are they intended to represent that the experiments below are all and only experiments performed. Example 1: A contactor was used for the purification of the waster water from fertilizer industry. The contactor as mentioned in Fig la was constructed with the resin inlet and purified water outlet at the top of the column while effluent liquid inlet and the spent resin outlet at the bottom of the column. The resin used was INDION 220 cation exchanger. A fixed bed (16 mm) of resin particle with effluent water was pumped upward and then gradually changing over to the continuous operation in the column with water and resin flowing counter-currently at constant flow rates. The height of the column was 300 mm while the internal diameter of the column was 0.108 m. The height between the stages was 65 mm. The water passed from the mesh opening (0.5 mm) smaller then the resin particle size. The central (L = 52 mm, ID = 16 mm) downspout and circumferential downspout (44 mm ID x 50 mm OD) are arranged alternatively in the stages. The different liquids that was purified by the contactor of the present disclosure includes waste water effluents from industries such as fertilizer, nitric acid producing plants, or from agricultural lands for removal of dissolved solutes such as arsenic, fluoride, nitrate, phosphate, etc. The resultant purified liquid has the purification level up to 90%. Example 2: Effect of resin flow rate and number of stages on effluent concentration on a desired liquid The effect of resin flow rate and number of stages on effluent concentration on the purification of a liquid was studied. Table 1 below describes the experimentally obtained effluent concentrations (-OH ions) for varying resin flow rates (0.008-0.022 kg/min) in multistage operation. The liquid flow rate, bed height and the feed concentration were held constant at 2.75 1pm, 5 mm and 0.01 M, respectively in each case. As observed from table 1, the effluent concentrations decreases with increase in the resin flow rates. The effluent concentrations with respect to the feed concentration varied between 0.89 and 0.84 in single stage, 0.875 and 0.50 in two-stage, 0.85 and 0.20 in three-stage, and 0.838 and 0.10 in the four-stage operations corresponding to the aforementioned resin flow rates. We claim: 1. A liquid-solid multi-stage contactor for purification of a liquid by removal of undesirable dissolved solutes or recovery of desirable dissolved solutes comprising; an inlet for loading/charging ion-exchange resin at the top of a column; the column consisting of at least three stages assembled together with flange joints; wherein each of the stages comprising; a mesh fitted on a ring, wherein the ring is sandwiched between the flange joints on its either sides, wherein the liquid flows upward from one stage to the next stage through the mesh; at least one downspout placed on the stage, wherein downspout is either central downspout located at the center of the stage or circumferential downspout located at the periphery of the stage through which ion-exchange resin particles move from one stage to the next stage, wherein, the central downspouts and the circumferential downspouts are located in the alternate stages; an inlet at the bottom of the column through which the liquid is pumped upwards in the column; an outlet at the top of the column for obtaining a resultant purified liquid; and an outlet at the bottom of the column for removal of the spent resin. 2. The contactor as claimed in claim 1, wherein the liquid is selected from a group consisting of waste water, slurry and biofluids; 3. The contactor as claimed in claim 1, wherein the ion-exchange resin is cationic or anionic ion-exchange resin. 4. The contactor as claimed in claim 1, wherein the dissolved solute is selected from a group consisting of arsenic ions, proteins, nitrogenous ions, solid sources of nutrients, fluoride ions, metal ions; 5. The contactor as claimed in claim 1, wherein the path length of the each fluidized solid moving across each stage is identical. 6. The contactor as claimed in claim 1, wherein the mass transfer rate between liquid and solid on each stage is uniform. 7. The contactor as claimed in claim 1, wherein up to 90% of undesirable dissolved solids are removed or up to 90% of desirable dissolved solids are recovered. 8. A process for purification of a liquid by removal of undesirable dissolved solutes using liquid-solid multi-stage contactor as claimed in claim 1 comprising; introducing an ion-exchange resin into said contactor from the top of the column, wherein said resin particles fill up each stages to a certain portion of the downspout height; introducing liquid from the bottom of the column, wherein the flow rate of liquid is gradually increased up to the minimum fluidization condition resulting in the cross-flow of the fluidized resin particles on the stage while water flows upward through the voids between the resins to obtain liquid devoid of undesirable dissolved solutes; 9. A process for recovering desirable dissolved solutes using liquid-solid multi-stage contactor as claimed in claim 1 comprising; introducing a ion-exchange resin into said contactor from the top of the column, wherein said resin particles fill up each stages to a certain portion of the downspout height; introducing liquid from the bottom of the column, wherein the flow rate of liquid is gradually increased up to the minimum fluidization condition resulting in the cross-flow of the fluidized resin particles on the stage while water flows upward through the voids between the resins to recover the desirable dissolved solutes.

Documents:

830-del-2007-Abstract-(05-09-2013).pdf

830-del-2007-abstract.pdf

830-del-2007-Claims-(05-09-2013).pdf

830-del-2007-claims.pdf

830-del-2007-Correspondence Others-(05-09-2013).pdf

830-del-2007-correspondence-others.pdf

830-del-2007-Description (Complete)-(05-09-2013).pdf

830-del-2007-description (complete).pdf

830-del-2007-Drawings-(05-09-2013).pdf

830-del-2007-drawings.pdf

830-del-2007-form-1.pdf

830-del-2007-form-2.pdf

830-del-2007-form-3.pdf

830-del-2007-form-5.pdf