WO2013131183A1 - Procédé de nanofiltration permettant d'améliorer la récupération de la saumure et l'élimination des sulfates - Google Patents

Procédé de nanofiltration permettant d'améliorer la récupération de la saumure et l'élimination des sulfates Download PDF

Info

Publication number
WO2013131183A1
WO2013131183A1 PCT/CA2013/050131 CA2013050131W WO2013131183A1 WO 2013131183 A1 WO2013131183 A1 WO 2013131183A1 CA 2013050131 W CA2013050131 W CA 2013050131W WO 2013131183 A1 WO2013131183 A1 WO 2013131183A1
Authority
WO
WIPO (PCT)
Prior art keywords
stream
brine
module
nanofiltration
outlet
Prior art date
Application number
PCT/CA2013/050131
Other languages
English (en)
Inventor
Norbert Eckert
Thomas Drackett
Ian Bailey
Allison MERZ
Felix Mok
Siamak LASHKARI
Ganapathy RAMASUBBU
Original Assignee
Chemetics Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Chemetics Inc. filed Critical Chemetics Inc.
Priority to CA2864478A priority Critical patent/CA2864478A1/fr
Priority to EP13758618.6A priority patent/EP2822674A4/fr
Publication of WO2013131183A1 publication Critical patent/WO2013131183A1/fr

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
    • B01D61/027—Nanofiltration
    • B01D61/0271—Nanofiltration comprising multiple nanofiltration steps
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/01—Products
    • C25B1/34—Simultaneous production of alkali metal hydroxides and chlorine, oxyacids or salts of chlorine, e.g. by chlor-alkali electrolysis
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
    • B01D61/025—Reverse osmosis; Hyperfiltration
    • B01D61/026—Reverse osmosis; Hyperfiltration comprising multiple reverse osmosis steps
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
    • B01D61/027—Nanofiltration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
    • B01D61/04—Feed pretreatment
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
    • C01D3/00—Halides of sodium, potassium or alkali metals in general
    • C01D3/04—Chlorides
    • C01D3/06—Preparation by working up brines; seawater or spent lyes
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • C02F1/442—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by nanofiltration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2311/00—Details relating to membrane separation process operations and control
    • B01D2311/04—Specific process operations in the feed stream; Feed pretreatment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2317/00—Membrane module arrangements within a plant or an apparatus
    • B01D2317/02—Elements in series
    • B01D2317/022—Reject series
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/101—Sulfur compounds
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/34—Nature of the water, waste water, sewage or sludge to be treated from industrial activities not provided for in groups C02F2103/12 - C02F2103/32
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2301/00—General aspects of water treatment
    • C02F2301/08—Multistage treatments, e.g. repetition of the same process step under different conditions

Definitions

  • the present invention pertains to nanofiltration processes and systems for recovering brine and for removing sulfate impurity from a brine stream in the industrial processing of chemicals.
  • it pertains to nanofiltration of brine streams in brine electrolysis processing.
  • Pressure driven membrane separation processes are known wherein organic molecules or inorganic ionic solutes in aqueous solutions are concentrated or separated to various degrees by the application of a positive osmotic pressure to one side of a filtration membrane.
  • Examples of such processes are reverse osmosis (RO), ultrafiltration (UF) and nanofiltration (NF).
  • RO reverse osmosis
  • UF ultrafiltration
  • NF nanofiltration
  • These pressure driven membrane processes employ a cross-flow mode of operation wherein only a portion of a feed stream solution is collected as a permeate solution and the rest is collected as a pass solution.
  • the exiting process stream which has not passed through the nanofiltration membrane is referred to as the "pass stream” and the exiting process stream which has passed through the membrane is referred to as the "permeate" stream.
  • NF membranes are structurally similar to RO membranes in that chemically, they typically are crosslinked aromatic polyamides, which are cast as a thin "skin layer” on top of a microporous polymer sheet support to form a composite membrane structure.
  • the separation properties of the membrane are controlled by the pore size and electrical charge of the "skin layer".
  • Such a membrane structure is usually referred to as a thin film composite (TFC).
  • TFC thin film composite
  • the NF membranes are characterized in having a larger pore size in its "skin layer” and a net negative electrical charge inside the individual pores. This negative charge is responsible for rejection of anionic species, according to the anion surface charge density.
  • NF membranes are available from known suppliers of RO and other pressure driven membranes.
  • the NF membranes are, typically, packaged as membrane modules.
  • a so-called "spiral wound" module is most popular, but other membrane module configurations, such as tubular membranes enclosed in a shell or plate- and-frame type, are also known.
  • a minimum pressure equal to the osmotic pressure difference between the feed/pass liquor on one side and the permeate liquor on the other side of the membrane must be applied since osmotic pressure is a function of the ionic strengths of the two streams.
  • osmotic pressure difference is moderated by the low NaCl rejection.
  • a pressure in excess of the osmotic pressure difference is employed to achieve practical permeate flux.
  • Industrial brine electrolysis processing plants may advantageously use nanofiltration in certain of the processing steps, and particularly in the removal of sulfate from the brine streams employed.
  • Various products are produced using brine as the starting material.
  • sodium chlorate is generally prepared by the electrolysis of sodium chloride brine to produce chlorine, sodium hydroxide and hydrogen. The chlorine and sodium hydroxide are immediately reacted to form sodium hypochlorite, which is then converted to chlorate and chloride under controlled conditions of pH and temperature.
  • chlorine and caustic soda are prepared by electrolysis of sodium chloride brine in an electrolytic cell or electrolyser, which contains a membrane to prevent chlorine and caustic soda reacting.
  • the sodium chloride salt used to prepare the brine for electrolysis generally contains impurities which, depending on the nature of the impurity and production techniques employed, can give rise to plant operational problems familiar to those skilled in the art. While the means of controlling these impurities are varied and include, purging them out of the system into alternative processes or to the drain, precipitation by conversion to insoluble salts, crystallization or ion exchange treatment, the control of anionic impurities presents more complex problems than that of cationic impurities. Sulfate ion is a common impurity in commercial salt and being an anion is a more complex impurity to deal with.
  • the sulfate When such salt is used directly, or in the form of a brine solution, and specific steps are not taken to remove the sulfate, the sulfate enters the electrolytic system. Sulfate ion maintains its identity under the conditions in the electrolytic system and, thus, accumulates and progressively increases in concentration in the system unless removed in some manner. In chlorate plants producing a liquor product, the sulfate ion will leave with the product liquor. In plants producing only crystalline chlorate, the sulfate remains in the mother liquor after the crystallization of the chlorate, and is recycled to the cells. Over time, the concentration of sulfate ion will increase and adversely affect electrolysis and cause operational problems due to localized precipitation in the electrolytic cells.
  • the sodium sulfate will concentrate and adversely effect the membrane, which divides the anolyte (brine) from the catholyte (caustic soda). It is industrially desirable however that sodium sulfate levels in concentrated brine, e.g., 300 g/L NaCl, be reduced to at least 20 g/L in chlorate production and about 10 g/L in chloralkali production.
  • US5587083 and US5858240 disclosed such use of nanofiltration systems in the application of sulfate removal from spent electrolysis brine.
  • nanofiltration processes because there was no buildup in concentration of sodium chloride in the pass liquor stream over its original level in the feed stream, it was possible to increase the content of sodium sulfate in the pass liquor to a higher level than would have been possible if the NaCl level of the pass liquor has increased. It was now possible to realize a desirable high % recovery, and, in the case of electrolysis brine, to minimize the volume of brine purge, and/or the size of a reactor and the amount of chemicals for an, optional, subsequent sulfate precipitation step.
  • US2008/0056981 discloses a method for at least partially removing soluble divalent anions from an aqueous divalent anion-containing brine solution comprising a crystal growth inhibitor (CGI) for the divalent anion.
  • CGI crystal growth inhibitor
  • the method comprises the process steps: obtaining a sodium chloride concentration between 100 g/L and saturation in the presence or absence of a CGI for sodium chloride or a sodium chloride concentration above saturation in the presence of a CGI for sodium chloride, and acidifying the solution to a pH below 11.5; subjecting the solution to a membrane filtration step thereby separating the brine solution into a brine stream being supersaturated for the divalent anion (concentrate), and a brine stream being undersaturated for the divalent anion (permeate); subjecting the supersaturated brine stream comprising the crystal growth inhibitor for the divalent anion to a crystallization process, removing crystallized divalent anion; and optionally, recycling the overflow of the crystallizer to the brine solution for subjecting it again to the membrane filtration step.
  • Nanofiltration techniques have also been suggested for use in completely different industrial processes.
  • US7314606 discloses a process for recovering sodium thiocyanate and separating impurities from industrial process solutions comprising sodium thiocyanate using nanofiltration techniques.
  • the present invention provides for desirable sulfate removal from process brine streams while recovering more of the brine salt for reprocessing.
  • this can result in substantial savings of valuable raw material and reduction in waste.
  • pure water is itself a valuable raw material that must be provided as an input.
  • the present invention can also provide for greater recovery of water which meets the purity requirements for the process.
  • the brine streams in typical brine electrolysis plants often contain sodium chlorate and/or bromate which are also therefore present to some extent in the effluent sulfate stream.
  • the present invention also results in a reduction of these species in the effluent sulfate stream.
  • a process and system are provided for recovering brine and for removing sulfate impurity from a brine stream in a nanofiltration system.
  • the brine stream here comprises an aqueous solution of NaCl
  • the system comprises a nanofiltration module.
  • the nanofiltration module itself comprises a nanofiltration membrane for rejecting sulfate, an inlet for a feed stream, an outlet for a permeate stream which has permeated through the membrane, and an outlet for a pass stream which has not permeated through the membrane.
  • the nanofiltration membrane may be any of those conventional membranes suitable for rejecting sulfate.
  • a dilution stream is introduced upstream of the feed stream inlet of the module, and thereby dilutes the feed stream at the feed inlet of the module and increases the amount of NaCl and water in the permeate stream at the permeate outlet of the module without substantially diluting the concentration of sulfate in the pass stream at the pass outlet of the module. And so, albeit more diluted, there is more brine salt present in total in the permeate stream which can be recovered. Of further advantage is that more water of sufficient purity for use in the brine electrolysis process can also be recovered.
  • the rejected pass stream on the other hand has a much reduced concentration of brine salt while roughly maintaining the same concentration of sulfate.
  • the brine stream may comprise additional species such as NaC10 3 and/or NaBr0 3 which can thus also be present in the effluent rejected pass stream.
  • Introducing a dilution stream in accordance with the invention also reduces the concentration of chlorate and/or bromate in the effluent pass stream and thus offers environmental advantages as well. Instead, an increased amount of chlorate and/or bromate is returned in the volume of permeate.
  • the dilution stream can desirably be water or any suitable, compatible liquid, such as a very dilute brine.
  • a very dilute brine Depending on the processing and systems involved, very dilute brine streams may possibly be derived from elsewhere in a specific plant.
  • An additional advantage of diluting the feed brine stream is that a more neutral, desirable stream pH (i.e. pH from about 5 to 9) can be obtained.
  • a preferred nanofiltration system may be a multi-stage system comprising at least a first nanofiltration module and a second nanofiltration module in series. A greater number of nanofiltration modules in series may be contemplated depending on the specific circumstances.
  • Each module in the system may comprise a nanofiltration membrane for rejecting sulfate, a feed stream inlet, a permeate stream outlet, and a pass stream outlet, wherein the pass stream outlet of the first module is connected to the feed stream inlet of the second module.
  • Introducing the dilution stream between the pass stream outlet of the first module and the feed stream inlet of the second module in such a series arrangement allows for more efficient use of the volume of the dilution stream. Desirable results can be obtained for instance for a volumetric flow rate ratio of the total dilution streams to that of the brine stream of less than or about 12:70. And with a sufficient number of module and dilution stream stages in series, the brine and other content in the process pass stream may be reduced enough to purify the sulfate in the pass stream to a commercial grade and thus become a valuable by-product as opposed to a waste.
  • an upstream brine stream comprising greater than or about 200 g/L NaCl and less than about 10 g/L Na 2 S0 4 can be subjected to the nanofiltration process to produce a pass stream comprising less than or about 50 g/L NaCl and greater than about 50 g/L Na 2 S0 4 .
  • the nanofiltration system may be particularly employed to remove sulfate impurity and recover substantial brine from the spent brine stream or product liquor coming from the electrolysers used in industrial brine electrolysis chemical processing.
  • a related brine electrolysis plant such as a chloralkali or chlorate plant, can thus comprise an electrolyser and the nanofiltration system in which the spent brine outlet of the electrolyser is connected to the feed stream inlet of the nanofiltration module.
  • a spent brine stream from an electrolyser may be fed to the nanofiltration system of the invention and the permeate stream recycled directly to the saturator.
  • the spent brine stream may first need to be concentrated in an evaporator (which concentrates both the NaCl brine salt and the sulfate in the stream).
  • Sulfate impurity may then be removed by feeding a portion of the now-concentrated spent brine stream to the nanofiltration system, recycling the permeate stream to the evaporator, and rejecting the sulfate-containing pass stream.
  • the nanofiltration system of the invention may be employed upstream of an electrolyser in a brine electrolysis chemical processing plant, that is wherein the brine inlet of the electrolyser is connected to the permeate stream outlet of the nanofiltration module.
  • the dilution stream can be introduced at a temperature substantially lower than that of the upstream brine stream.
  • a heat exchanger for cooling the upstream brine stream may not be required.
  • the system may thus be absent the heat exchanger which may be employed for cooling the upstream brine stream in conventional systems.
  • Figure 1 shows a simplified schematic of an industrial chloralkali plant of the prior art comprising an electrolyser and a nanofiltration sulfate removal system.
  • Figure 2 shows a simplified schematic of a multi-stage sulfate removal system of the prior art comprising multiple nanofiltration membrane modules in series and an upstream heat exchanger.
  • Figure 3 shows a simplified schematic of a multi-stage sulfate removal system of the invention comprising multiple nanofiltration membrane modules in series and conduits for introducing dilution water.
  • Figure 4 shows a simplified schematic of the modeled multi-stage sulfate removal system of the Examples comprising three nanofiltration membrane modules in series and two conduits for introducing dilution water.
  • Figure 5 shows the same modeled multi-stage sulfate removal system as Figure 4 except without any conduits for introducing dilution water.
  • An exemplary industrial brine electrolysis plant is a chloralkali plant. Such plants are commonly found throughout the world.
  • a simplified schematic for a prior art chloralkali plant 10 is shown in Figure 1.
  • NaCl based brine undergoes electrolysis in electrolyser 1 to produce primary products chlorine gas at anode 2 and NaOH and hydrogen gas at cathode 3.
  • Other products can then be obtained as a result of an additional series of reactions between the primary products.
  • sodium chlorate product, NaC10 3 can be obtained by allowing the chlorine and NaOH caustic to intermix under appropriate controlled conditions.
  • catholyte is provided to cathode inlet 3a of electrolyser 1 from catholyte tank 4.
  • Spent catholyte is withdrawn from cathode outlet 3b and one portion is recycled back to catholyte tank 4 while another portion is removed to obtain a supply of product (e.g. NaOH caustic product).
  • Anolyte brine is prepared in saturator 5 and then provided from saturator outlet 5d to anode inlet 2a of electrolyser 1.
  • Spent anolyte is withdrawn from anode outlet 2b and is recycled back to saturator 5 at recycle inlet 5c for reuse.
  • the appropriate concentration of NaCl brine for the electrolysis process is maintained by adding the right amounts of process solid crystalline salt and process water at saturator inlets 5a and 5b respectively.
  • nanofiltration system 20 is provided for that purpose as a branch loop in the recycling anolyte line between anode outlet 2b and saturator recycle inlet 5c. Sulfate is continually removed from the circulating anolyte stream by directing a portion of the spent anolyte to feed 20a of nanofiltration system 20. Purified brine permeate is returned to the circulating anolyte from permeate outlet 20b and a reject stream concentrated in sulfate is removed from circulation at pass outlet 20c. (Note that many other components and/or subsystems, such as pumps, heat exchangers, control subsystems, are typically employed in an industrial chloralkali plant like that shown in Figure 1, but these have been omitted for simplicity.)
  • FIG. 2 shows a more detailed schematic of a prior art multi-stage nanofiltration system that might be used to purify spent anolyte brine by removing sodium sulfate in the chloralkali plant of Figure 1.
  • nanofiltration system 20 is shown as comprising several (three) nanofiltration membrane modules 21, 22, 23 connected in series. (As known to those of skill in the art, the number of modules employed in series may vary from situation to situation. And further, modules may be employed in parallel arrangements as well in order to handle situations involving larger volumes.)
  • Process (spent anolyte) brine stream 26 is provided to system feed inlet 20a and directed to high pressure pump 24 which boosts the brine stream pressure to a value suitable for nanofiltration.
  • the temperature of the provided and/or boosted brine stream is however undesirably high.
  • heat exchanger 25 is used to lower the temperature to an appropriate level for nanofiltration.
  • the pressure-boosted, cooled brine stream is supplied to the series of nanofiltration modules at feed inlet 21 a of the first nanofiltration module 21.
  • Series modules 21, 22, and 23 comprise nanofiltration membranes suitable for rejecting sulfate, for instance single spiral wound type nanofiltration units.
  • Modules 21, 22, 23 comprise feed stream inlets 21a, 22a, 23a, permeate stream outlets 21b, 22b, 23b and pass stream outlets 21c, 22c, and 23c respectively.
  • the modules are connected in series by connecting the pass stream outlet from an upstream module to the feed stream inlet of the adjacent module downstream (e.g. pass stream outlet 21c is connected to feed stream inlet 22a).
  • Process anolyte brine 26 comprising NaCl brine salt and Na 2 S0 4 impurity is thus concentrated in sulfate in stages in the pass streams from the nanofiltration modules while the brine salt concentration in both the pass streams and the permeate streams is only slightly reduced.
  • the pass stream from final module 23 in the series is rejected at system pass outlet 20c.
  • the several permeate streams from outlets 21b, 22b, and 23b may be combined into a single resultant purified brine stream which is directed back to the recycle brine line from output 20b.
  • components such as pressure control valves, sensors, and other hardware which are typically provided for process control as is known to those skilled in the art.
  • nanofiltration systems such as that shown in Figure 2 have served the brine electrolysis industry well for many years, there is ever growing demand to conserve resources, increase process efficiency, and minimize effluents in these large industrial systems.
  • the nanofiltration processes and systems of the invention allow for greater recovery of precious electrolysis grade brine salt and for improvements in process efficiency.
  • FIG 3 shows a schematic of an improved multi-stage nanofiltration system of the invention suitable for use in the chloralkali plant of Figure 1.
  • the system of Figure 3 comprises high pressure pump 34 to boost the pressure of brine stream 26 suitable for nanofiltration.
  • nanofiltration modules 31, 32, and 33 are provided in series purify the brine stream and remove sulfate impurity therefrom.
  • process (spent anolyte) brine stream 26 is provided to system feed inlet 30a, its pressure is boosted by pump 34 and the pressure -boosted brine stream is supplied to the series of nanofiltration modules at feed inlet 31a of the first nanofiltration module 31.
  • Modules 31, 32, 33 comprise feed stream inlets 31a, 32a, 33a, permeate stream outlets 31b, 32b, 33b and pass stream outlets 31c, 32c, and 33c respectively. Again, the modules are connected in series by connecting the pass stream outlet from an upstream module to the feed stream inlet of the adjacent module downstream (e.g. pass stream outlet 3 lc is connected to feed stream inlet 32a).
  • a dilution stream or streams is provided at one or more inlets to modules 31, 32, and 33 to desirably increase the recovery of brine salt.
  • a dilution stream can be introduced at one or more of locations 35a, 35b, or 35c.
  • the dilution stream can desirably be water or any suitable, compatible liquid, such as a very dilute brine. Consequently there is an initial reduction in concentration of all species in the diluted feed stream. Further, there is a dilution in all the species that permeate through the module membrane and hence in the respective permeate. And there is a similar reduction in concentration of monovalent species in the respective pass streams (e.g.
  • the nanofiltration system of Figure 3 outputs a reject pass stream at outlet 30c with a similar concentration of sulfate as the system of Figure 2, but with a much reduced concentration of brine, chlorate, bromate, and any other monovalent species. And so, the system of Figure 3 retains more total brine, chlorate, and bromate in the permeate streams from module permeate outlets 31b, 32b, and 33b than does the system of Figure 2, albeit diluted to a lower concentration.
  • introducing the dilution stream after the first module in the series i.e. at 35b between the pass stream outlet of the first module and the feed stream inlet of the second module, or for instance at 35c) allows for more efficient use of the volume of the dilution stream.
  • desirable results can be obtained for example in a system comprising three nanofiltration modules in series and employing two such dilutions for a volumetric flow rate ratio of the total dilution streams to that of the brine stream of less than or about 12:70.
  • the volume of fluid making up the dilution stream is obtained from elsewhere in the overall chloralkali plant 10.
  • water for a dilution stream may be obtained from the process water otherwise provided at inlet 5b of saturator 5. Since much of this water is recycled back to saturator 5 after filtration anyway, the requirements for additional process fluid can be markedly reduced and perhaps even eliminated.
  • water or other fluids such as very dilute brine may be obtained from elsewhere in the system for use as a source of volume for a dilution stream.
  • the present approach can offer other advantages along with the recovery of brine salt and efficiency. Introducing a dilution stream can be generally advantageous in that the brine stream feed to a given nanofiltration module is at a more desirable stream pH.
  • the pass stream comprising the rejected concentrated sulfate is often considered a waste product that may be discharged to sewer.
  • the brine and other content in the process pass stream may be reduced enough to purify the sulfate in the pass stream to that of commercial grade for industrial purposes and thus become a valuable by-product instead of a waste.
  • the heat exchanger often employed in conventional sulfate removal systems may no longer be required.
  • the dilution stream being introduced at a temperature substantially lower than that of the upstream brine stream allows for the system to be absent the heat exchanger employed for cooling the upstream brine stream in such conventional systems.
  • Figure 3 illustrates such an embodiment absent a heat exchanger.
  • the several permeate streams from outlets 31b, 32b, and 33b in Figure 3 may be combined into a single resultant purified, but more diluted, brine stream which is directed back to the recycle brine line. It may however be desirable to re -concentrate a permeate stream or combination of permeate streams prior to recycling it back to the recycle brine line.
  • Figure 3 illustrates an optional arrangement for re -concentrating just the permeate stream from module 33 prior to combining with the permeate streams from modules 31 and 32.
  • permeate from permeate outlet 33b is directed first to inlet 36a of osmotic membrane distillation module 36 where it is concentrated and output from outlet 36b to then be combined with the other permeate streams from modules 31 and 32.
  • the preceding discusses a chloralkali chemical processing plant in which the initial process brine is prepared in a saturator and the permeate stream from the nanofiltration system is recycled directly to the saturator.
  • another conventional configuration for the preceding chloralkali process uses well brine as the initial brine supply as opposed to concentrated crystal brine.
  • the spent anolyte stream leaving the electrolyser needs to be concentrated in order to be recycled since there is no crystalline salt supply available to mix therewith.
  • an evaporator subsystem is typically employed to concentrate the spent anolyte brine stream and this will obviously concentrate any Na 2 S0 4 present in the stream as well.
  • nanofiltration system of the invention in the evaporator subsystem instead in order to remove sulfate from the stream.
  • the following Examples have been included to illustrate certain aspects of the invention but should not be construed as limiting in any way. Those skilled in the art can be expected to appreciate how to modify the nanofiltration system and process according to the specifics of a given industrial application for brine recovery and sulfate removal. Examples
  • the modules were assumed to comprise a nanofiltration filtration selected for this application.
  • spent brine stream 40a was supplied initially to module 41.
  • Two dilution streams comprising pure (i.e. demineralised) water were introduced at locations 45b and 45c into the feed inlets of nanofiltration modules 42 and 43 respectively as depicted in Figure 4. Both dilution streams were introduced at flow rates of 6 m 3 /hr, temperatures of 75 °C, and pressures of 40 bar. The ratio of total dilution water volume supplied to that of the spent brine stream was thus 12:70.
  • the calculated flow rates and concentrations of the involved species at various locations throughout system 40 are given on Figure 4.
  • the net combined system permeate stream at system permeate outlet 40b contained 179 g/L NaCl and 2.6 g/L Na 2 S0 4 at a flow rate of 77 m 3 /hr.
  • the final system pass stream at system pass outlet 40c contained 50 g/L NaCl and 100 g/L Na 2 S0 4 at a flow rate of 5 m 3 /hr.

Abstract

Dans un système de nanofiltration pour éliminer les impuretés de type sulfates d'un courant de saumure aqueuse et pour récupérer la saumure, l'introduction d'un flux de dilution en amont du flux d'alimentation entrée d'un module de nanofiltration dans le système dilue le flux d'alimentation. Ceci augmente la quantité de sel de la saumure et de l'eau obtenue dans le flux de perméat sans dilution substantielle de la concentration de sulfates dans le flux de passage et permet, par conséquent, d'obtenir une récupération accrue de la saumure tout en éliminant efficacement les impuretés de type sulfates. Le système et le procédé sont particulièrement appropriés pour la récupération de la saumure et l'élimination des impuretés de type sulfates d'un flux de saumure dans une installation d'électrolyse de saumure. Dans un système classique, l'échangeur de chaleur généralement utilisé pour refroidir le flux d'alimentation peut être omis si le flux de dilution est introduit à une température appropriée inférieure à celle du flux d'alimentation .
PCT/CA2013/050131 2012-03-07 2013-02-20 Procédé de nanofiltration permettant d'améliorer la récupération de la saumure et l'élimination des sulfates WO2013131183A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
CA2864478A CA2864478A1 (fr) 2012-03-07 2013-02-20 Procede de nanofiltration permettant d'ameliorer la recuperation de la saumure et l'elimination des sulfates
EP13758618.6A EP2822674A4 (fr) 2012-03-07 2013-02-20 Procédé de nanofiltration permettant d'améliorer la récupération de la saumure et l'élimination des sulfates

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US201261607722P 2012-03-07 2012-03-07
US61/607,722 2012-03-07

Publications (1)

Publication Number Publication Date
WO2013131183A1 true WO2013131183A1 (fr) 2013-09-12

Family

ID=49115825

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CA2013/050131 WO2013131183A1 (fr) 2012-03-07 2013-02-20 Procédé de nanofiltration permettant d'améliorer la récupération de la saumure et l'élimination des sulfates

Country Status (3)

Country Link
EP (1) EP2822674A4 (fr)
CA (1) CA2864478A1 (fr)
WO (1) WO2013131183A1 (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016005996A3 (fr) * 2014-07-10 2016-06-09 Geist Research Pvt. Ltd. Procédé et système de récupération de sulfate de sodium anhydre à partir d'un flux de rejet d'un système d'élimination de sulfates
CN111362471A (zh) * 2020-04-17 2020-07-03 莱特莱德（北京）环境技术股份有限公司 煤化工副产氯化钠饱和溶液中脱硫酸钠的装置
WO2021034332A1 (fr) * 2019-08-22 2021-02-25 Saline Water Conversion Corporation Concentration d'ions multivalents à l'aide d'une nanofiltration à plusieurs étages
CN115298136A (zh) * 2020-03-16 2022-11-04 杜邦安全与建筑公司 硫酸的浓缩
US11806668B2 (en) 2021-12-14 2023-11-07 Saline Water Conversion Corporation Method and system for extraction of minerals based on divalent cations from brine
US11884567B2 (en) 2019-04-01 2024-01-30 Saline Water Conversion Corporation Desalination brine concentration system and method

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4586993A (en) * 1985-05-31 1986-05-06 Stearns Catalytic World Corporation Control of sulfates in membrane cell chlor-alkali process
US20060144789A1 (en) * 2004-12-06 2006-07-06 Cath Tzahi Y Systems and methods for purification of liquids
WO2006087302A1 (fr) * 2005-02-18 2006-08-24 Akzo Nobel N.V. Procede d'elaboration de sel
WO2010077895A1 (fr) * 2008-12-30 2010-07-08 General Electric Company Installation de désalinisation de l'eau et système de production d'eau pure et de sel
WO2010132104A1 (fr) * 2009-05-13 2010-11-18 Carollo Engineers, P.C. Système et procédé de contrôle de l'entartrage par un traitement à la saumure

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5587083A (en) * 1995-04-17 1996-12-24 Chemetics International Company Ltd. Nanofiltration of concentrated aqueous salt solutions
EP1586562A1 (fr) * 2004-03-30 2005-10-19 Council of Scientific and Industrial Research Récupération de thiocyanate de natrium à partir d'une solution provenant d'un procédé industriel par nanofiltration
CA2469769A1 (fr) * 2004-06-04 2005-12-04 Aker Kvaerner Canada Inc. Appareil et methode pour concentrer une solution d'halogenure de metal alcalin usee au moyen d'une distillation sur membrane osmotique
CN201144172Y (zh) * 2007-12-27 2008-11-05 张艳 纳滤膜脱除盐水中硫酸根的装置
WO2011102848A1 (fr) * 2010-02-17 2011-08-25 Katana Energy Llc Installation de dessalement de l'eau de mer sans rejets comprenant l'extraction de minéraux intégrée à la production d'une énergie à cycle combiné au gaz naturel

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4586993A (en) * 1985-05-31 1986-05-06 Stearns Catalytic World Corporation Control of sulfates in membrane cell chlor-alkali process
US20060144789A1 (en) * 2004-12-06 2006-07-06 Cath Tzahi Y Systems and methods for purification of liquids
WO2006087302A1 (fr) * 2005-02-18 2006-08-24 Akzo Nobel N.V. Procede d'elaboration de sel
WO2010077895A1 (fr) * 2008-12-30 2010-07-08 General Electric Company Installation de désalinisation de l'eau et système de production d'eau pure et de sel
WO2010132104A1 (fr) * 2009-05-13 2010-11-18 Carollo Engineers, P.C. Système et procédé de contrôle de l'entartrage par un traitement à la saumure

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016005996A3 (fr) * 2014-07-10 2016-06-09 Geist Research Pvt. Ltd. Procédé et système de récupération de sulfate de sodium anhydre à partir d'un flux de rejet d'un système d'élimination de sulfates
US11884567B2 (en) 2019-04-01 2024-01-30 Saline Water Conversion Corporation Desalination brine concentration system and method
WO2021034332A1 (fr) * 2019-08-22 2021-02-25 Saline Water Conversion Corporation Concentration d'ions multivalents à l'aide d'une nanofiltration à plusieurs étages
US11795071B2 (en) 2019-08-22 2023-10-24 Saline Water Conversion Corporation Multi-valent ion concentration using multi-stage nanofiltration
CN115298136A (zh) * 2020-03-16 2022-11-04 杜邦安全与建筑公司 硫酸的浓缩
CN111362471A (zh) * 2020-04-17 2020-07-03 莱特莱德（北京）环境技术股份有限公司 煤化工副产氯化钠饱和溶液中脱硫酸钠的装置
US11806668B2 (en) 2021-12-14 2023-11-07 Saline Water Conversion Corporation Method and system for extraction of minerals based on divalent cations from brine

Also Published As

Publication number Publication date
EP2822674A1 (fr) 2015-01-14
CA2864478A1 (fr) 2013-09-12
EP2822674A4 (fr) 2015-12-16

Similar Documents

Publication Publication Date Title
US20140299546A1 (en) Nanofiltration process for enhanced brine recovery and sulfate removal
US5587083A (en) Nanofiltration of concentrated aqueous salt solutions
CA2504848C (fr) Appareil et methode de distillation a membrane d'osmose
EP2822674A1 (fr) Procédé de nanofiltration permettant d'améliorer la récupération de la saumure et l'élimination des sulfates
US10947143B2 (en) Desalination brine concentration system and method
JP6053631B2 (ja) 淡水化装置及び淡水化方法、並びに淡水、塩及び有価物の併産方法
WO2007132477A1 (fr) Processus de prétraitement des eaux salées alimentant des usines de dessalement
JP2008516883A (ja) 塩水から２価アニオンの可溶性塩を結晶化させる方法
US20150165381A1 (en) Nanofiltration process for impurity removal
DK1848661T3 (en) PROCEDURE FOR THE PREPARATION OF CHLOR OR SODIUM CHLORATE
CN107098360A (zh) 利用草甘膦废盐水生产离子膜烧碱用原料的方法
US20190023569A1 (en) High strength, low salt hypochlorite production
US20240116002A1 (en) Systems and methods for direct lithium hydroxide production
US7314606B2 (en) Recovery of sodium thiocyanate from industrial process solution using nanofiltration technique
KR20100135041A (ko) 무기염 함유 폐액의 처리방법 및 장치
WO2021152356A1 (fr) Procédé et système de récupération d'eau et de sels à partir de rejet de saumure d'une installation de dessalement conduisant à un système de rejet zéro liquide
AU2021435424A1 (en) System for the production of lithium hydroxide (lioh) directly from lithium chloride (lici), without the need for the intermediate production of lithium carbonate or the like
WO2020110153A1 (fr) Système d'extraction continue d'eau pure à partir de charge d'alimentation avec une resaturation et une réutilisation de l'extraction
WO2013183993A1 (fr) Processus de séparation de membrane assisté par cristallisation
EP1586562A1 (fr) Récupération de thiocyanate de natrium à partir d'une solution provenant d'un procédé industriel par nanofiltration
NO344281B1 (no) Fremgangsmåte for fremstilling av klorinneholdende forbindelser
CN106145258A (zh) 一种溶液中离子的交换和浓缩方法

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 13758618

Country of ref document: EP

Kind code of ref document: A1

ENP Entry into the national phase

Ref document number: 2864478

Country of ref document: CA

NENP Non-entry into the national phase

Ref country code: DE

REEP Request for entry into the european phase

Ref document number: 2013758618

Country of ref document: EP

WWE Wipo information: entry into national phase

Ref document number: 2013758618

Country of ref document: EP