A continuous ion exchange desalination system and method

Abstract

The application relates to the technical field of ion exchange, and discloses a continuous ion exchange desalination system and method. The application adopts a continuous ion exchange (cation exchange device and anion exchange device are alternately connected in series) method to realize the alternate adsorption and regeneration of the two kinds of resins, and compared with the process method of the continuous ion exchange ion exchange device + continuous ion exchange anion exchange device, the method has higher precision, smaller conductivity, can adjust the number of adsorption zones according to the properties of the liquid, further controls the conductivity, can realize the multistage alternate series adsorption of the cation column and the anion column, and the water quality is higher. Compared with the process method of the continuous ion exchange cation bed + continuous ion exchange anion bed, the number of pneumatic valves and pipelines is greatly reduced, the investment can be reduced, the system failure can be reduced, the maintenance is simple, the automatic control program is simpler and clearer, and the system control and operation are simpler.

Description

Technical Field

[0001] This invention relates to the field of ion exchange technology, and more specifically to a continuous ion exchange desalination system and method. Background Technology

[0002] Traditional ion exchange desalination methods involve setting up multiple cation exchange resin towers and anion exchange resin towers separately, forming two independent systems. The cation exchange resin tower system removes cations, and the anion exchange resin tower system removes anions. Both the anion and cation exchange resins are then regenerated and activated separately. The operation of these two independent systems is complex, requiring a significantly increased number of automatic control valves, resulting in higher investment costs and more complex program control. In applications such as wastewater treatment, inulin processing, plant extraction, and ultrapure water treatment, the traditional series connection of cation and anion exchange resin towers involves a large number of stages, leading to high investment costs, system complexity, and poor treatment efficiency. The combined application of cation and anion exchange resin towers is limited to a very small number of towers connected in series, and the overly complex process flow and piping layout restricts its application in multi-stage series connection to improve treatment efficiency. Summary of the Invention

[0003] In view of this, the present invention provides a continuous ion exchange desalination method with good desalination effect, wide application, low cost and simple process flow.

[0004] In a first aspect, the present invention provides a continuous ion exchange system, the continuous ion exchange system comprising an adsorption zone, an elution zone, an alkali regeneration / activation zone, a water washing alkali removal zone, an acid regeneration zone, a water washing acid removal zone, and a reverse dilution zone; wherein:

[0005] The adsorption zone, the elution zone, and the alkali regeneration / activation zone are arranged in sequence, and the acid regeneration zone, the water washing acid removal zone, and the reverse dilution zone are arranged in sequence. The water washing alkali removal zone is arranged adjacent to the acid regeneration zone and the reverse dilution zone, respectively.

[0006] The adsorption zone, the elution zone, the alkali regeneration / activation zone, the water washing alkali removal zone, and the reverse dilution zone each include at least one set of ion exchange devices, and each set of ion exchange devices includes a cation exchange device and an anion exchange device connected in series; the acid regeneration zone and the water washing acid removal zone each include only cation exchange devices.

[0007] Each group of ion exchange devices further includes a first feed valve and a first discharge valve. The cation exchange devices in the acid regeneration zone and the water washing deacidification zone each include a second feed valve and a second discharge valve. By switching the first feed valve, the first discharge valve, the second feed valve, and the second discharge valve, each cation exchange device completes the adsorption, elution, activation, regeneration, and de-dilution process in one process cycle, and each anion exchange device completes the adsorption, elution, regeneration, and de-dilution process in one process cycle.

[0008] In one optional embodiment, the water washing and alkali removal zone includes a water washing and alkali removal zone one and a water washing and alkali removal zone two, wherein the water washing and alkali removal zone one is arranged adjacent to the acid regeneration zone, and the water washing and alkali removal zone two is arranged adjacent to the anti-dilution zone.

[0009] In one optional embodiment, the first water washing and alkali removal zone includes at least one set of the ion exchange devices, and the second water washing and alkali removal zone includes only anion exchange devices.

[0010] In one optional embodiment, the number of anion exchange devices in the second water washing and alkali removal zone is the same as the sum of the number of cation exchange devices in the acid regeneration zone and the water washing and acid removal zone.

[0011] In one optional embodiment, the cation exchange device is filled with a cation exchange resin, wherein the cation exchange resin is at least one of D001 resin, 001X7 resin, and LX-160 resin.

[0012] In one optional embodiment, the anion exchange device is filled with anion exchange resin, wherein the anion exchange resin is at least one of D301 resin, LX-6703 resin, and LX-67 resin.

[0013] Secondly, the present invention provides a continuous ion exchange desalination method, wherein the above-mentioned continuous ion exchange system is used; the continuous ion exchange desalination method includes the following steps:

[0014] Obtain a desalination solution containing water-soluble inorganic salts, as well as at least one of phenolic compounds, proteins, and ester compounds;

[0015] The desalted liquid is continuously introduced into the inlet of the adsorption zone of the continuous ion exchange system, and the desalted liquid is collected at the outlet of the adsorption zone.

[0016] By switching valves, each cation exchanger in the continuous ion exchange system completes the adsorption, elution, activation, regeneration, and de-dilution process in one process cycle, and each anion exchanger in the continuous ion exchange system completes the adsorption, elution, regeneration, and de-dilution process in one process cycle.

[0017] In one alternative embodiment, the adsorption flow rate is 6 BV / h-10 BV / h.

[0018] In one alternative implementation, the elution flow rate is 2 BV / h-3 BV / h.

[0019] In one optional embodiment, the flow rate of the alkali regeneration / activation is 1 BV / h-2 BV / h.

[0020] In one optional embodiment, the flow rate of the water washing for alkali removal is 2 BV / h-3 BV / h.

[0021] In one alternative embodiment, the acid regeneration flow rate is 1 BV / h - 2 BV / h.

[0022] In one optional embodiment, the flow rate of the water washing for acid removal is 2 BV / h-3 BV / h.

[0023] In one alternative implementation, the de-dilution flow rate is 2 BV / h-3 BV / h.

[0024] In one optional embodiment, the alkaline reagent used in the alkali regeneration / activation zone is an aqueous solution of at least one of sodium hydroxide and lithium hydroxide, with an alkali concentration of 1 mol / L to 1.5 mol / L.

[0025] In one optional embodiment, the acidic reagent used in the acid regeneration zone is an aqueous solution of at least one of sulfuric acid and hydrochloric acid, with an acid concentration of 1 mol / L to 1.5 mol / L.

[0026] In one optional embodiment, the eluent used in the elution zone, the water washing de-alkali zone, and the water washing de-acid zone is pure water.

[0027] In one optional embodiment, the reagent used in the de-dilution zone is the adsorbed and desalted feed solution.

[0028] In one optional embodiment, the content of water-soluble inorganic salts in the desalination solution is 1200 mg / L-4000 mg / L.

[0029] In one optional embodiment, the content of phenolic compounds is 10 mg / L-50 mg / L.

[0030] In one alternative embodiment, the protein content is 5 mg / L-20 mg / L.

[0031] In one optional embodiment, the content of the ester compound is 5 mg / L-10 mg / L.

[0032] In one optional embodiment, the molar ratio of anions in the desalination solution to alkali in the alkaline reagent is 1:1.03-1.05.

[0033] In one optional embodiment, the molar ratio of cations in the desalting solution to acids in the acidic reagent is 1:1.01-1.02.

[0034] In one optional implementation, the interval between each switch is 10 min to 120 min, the operating temperature is 10℃ to 40℃, and the operating pressure is 0.2 MPa to 0.4 MPa.

[0035] Thirdly, the present invention provides an application of the above-mentioned continuous ion exchange desalination method in wastewater treatment, inulin preparation, plant extraction, and ultrapure water treatment.

[0036] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0037] 1. The continuous ion exchange desalination system provided by the present invention includes an adsorption zone, an elution zone, an alkali regeneration / activation zone, a water washing alkali removal zone, an acid regeneration zone, a water washing acid removal zone, and a reverse dilution zone; wherein: the adsorption zone, the elution zone, and the alkali regeneration / activation zone are arranged sequentially; the acid regeneration zone, the water washing acid removal zone, and the reverse dilution zone are arranged sequentially; the water washing alkali removal zone is adjacent to the acid regeneration zone and the reverse dilution zone, respectively; each of the adsorption zone, the elution zone, the alkali regeneration / activation zone, the water washing alkali removal zone, and the reverse dilution zone includes at least one set of ion exchange devices, and each set of ion exchange devices includes a cation exchange device connected in series and An anion exchange device is included; both the acid regeneration zone and the water washing deacidification zone consist only of cation exchange devices; each group of ion exchange devices further includes a first feed valve and a first discharge valve, and the cation exchange devices in both the acid regeneration zone and the water washing deacidification zone include a second feed valve and a second discharge valve. By switching the first feed valve, the first discharge valve, the second feed valve, and the second discharge valve, each cation exchange device completes the adsorption, elution, activation, regeneration, and reverse dilution process in one process cycle, and each anion exchange device completes the adsorption, elution, regeneration, and reverse dilution process in one process cycle. This invention uses a continuous ion exchange method (cation exchange device and anion exchange device in series) to achieve alternating adsorption and regeneration of anion and cation resins. Compared with the continuous ion exchange cation exchange device + continuous ion exchange anion exchange device process, it has higher precision, lower conductivity, and the number of adsorption stages can be adjusted according to the properties of the feed solution to further control the conductivity. It can achieve multi-stage alternating series adsorption of cation and anion columns, resulting in higher effluent quality.

[0038] Compared with the process of continuous ion exchange cation exchange device + continuous ion exchange anion exchange device, the continuous ion exchange desalination method provided by this invention greatly reduces the number of pneumatic valves and pipelines, which can reduce investment, reduce system failures, simplify maintenance, make the automatic control program simpler and clearer, and make system control and operation simpler.

[0039] The continuous ion exchange desalination method provided by this invention differs from conventional ion exchange desalination methods, which typically involve multiple cation exchange and anion exchange resin towers set up separately, each with one inlet, one outlet, and one series connection, requiring three connecting pipes and three pneumatic valves. In this invention, the raw material adsorption group, elution group, alkali regeneration and activation group, and elution alkali group all operate in an alternating combination of anion exchange resin towers and cation exchange resin towers, with each tower receiving input from and output from the anion exchange resin tower. This requires only two connecting pipes and two pneumatic valves, resulting in simpler control and a lower failure rate.

[0040] 2. The continuous ion exchange desalination method provided by this invention is applicable to the desalination of organic substances such as polyphenols, proteins, and esters, as these components are not adsorbed by the resin but will contaminate it. This invention simultaneously completes cation resin activation and anion resin regeneration in one operation stage, saving alkali and washing water consumption, improving product quality, and reducing waste liquid discharge. Attached Figure Description

[0041] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0042] Figure 1 This is the continuous ion exchange desalination system of Embodiment 2 of the present invention, wherein 1-12 are cation exchange resin towers, ①- It is an anion exchange resin tower. Detailed Implementation

[0043] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0044] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0045] The continuous ion exchange system provided by this invention includes an adsorption zone, an elution zone, an alkali regeneration / activation zone, a water washing alkali removal zone, an acid regeneration zone, a water washing acid removal zone, and a de-dilution zone. The adsorption zone, elution zone, and alkali regeneration / activation zone are arranged sequentially, as are the acid regeneration zone, water washing acid removal zone, and de-dilution zone. The water washing alkali removal zone is adjacent to both the acid regeneration zone and the de-dilution zone. Each of the adsorption zone, elution zone, alkali regeneration / activation zone, water washing alkali removal zone, and de-dilution zone includes at least one set of ion exchange devices, and each set of ion exchange devices includes a cation exchange device and an anion exchange device connected in series. The acid regeneration zone and the water washing deacidification zone each include only cation exchange devices; each group of ion exchange devices also includes a first feed valve and a first discharge valve. The cation exchange devices in the acid regeneration zone and the water washing deacidification zone each include a second feed valve and a second discharge valve. By switching the first feed valve, the first discharge valve, the second feed valve, and the second discharge valve, each cation exchange device completes the adsorption, elution, activation, regeneration, and de-dilution process in one process cycle, and each anion exchange device completes the adsorption, elution, regeneration, and de-dilution process in one process cycle.

[0046] When the feed solution to be desalted flows into the elution zone, it is used to remove salt from the feed solution; the eluent flows into the elution zone to recover the feed solution in the resin tower; the alkaline reagent flows into the alkali regeneration / activation zone to activate the cation exchange resin tower and regenerate the anion exchange resin tower; the eluent flows into the water washing alkali removal zone to recover the alkaline reagent and avoid reaction with the subsequent acidic reagent, which would affect the desalination effect; the acidic reagent flows into the acid regeneration zone to regenerate the cation exchange resin tower; the eluent flows into the water washing acid removal zone to recover the acidic reagent; finally, the water in the resin gaps is pushed out by the adsorption desalted feed solution to ensure that the concentration of the product is not diluted during the analysis.

[0047] by Figure 1 For example, the adsorption zone includes cation exchange resin tower No. 1, anion exchange resin tower No. ①, cation exchange resin tower No. 2, and anion exchange resin tower No. ②, while the elution zone includes cation exchange resin tower No. 11, ... Anion exchange resin tower No. 12, cation exchange resin tower and The anion exchange resin tower is divided into four zones: Alkali regeneration / activation zone (including cation exchange resin towers 9, 9, 10, and 10); water washing for alkali removal zone 1 (including cation exchange resin towers 8 and 8); acid regeneration zone (including cation exchange resin towers 6 and 7); water washing for acid removal zone (including cation exchange resin towers 4 and 5); water washing for alkali removal zone 2 (including anion exchange resin towers 4, 5, 6, and 7); and reverse dilution zone (including cation exchange resin tower 3 and 3). When switching between cycles, all resin towers move two towers in the opposite direction of fluid flow. Cation exchange resin tower 1 and anion exchange resin tower 1 in the adsorption zone enter the elution zone; cation exchange resin tower 11 in the elution zone... Anion exchange resin tower No. 1 enters the alkali regeneration / activation zone; cation exchange resin towers No. 9 and No. 9 anion exchange resin towers in the alkali regeneration / activation zone enter the first water washing alkali removal zone; cation exchange resin tower No. 8 in the first water washing alkali removal zone enters the acid regeneration zone, and anion exchange resin tower No. 8 enters the second water washing alkali removal zone; cation exchange resin tower No. 6 in the acid regeneration zone enters the acid washing zone; cation exchange resin tower No. 4 in the acid washing zone and anion exchange resin tower No. 4 in the second water washing alkali removal zone enter the reverse dilution zone; cation exchange resin tower No. 3 and anion exchange resin tower No. 3 in the reverse dilution zone become the last two resin towers in the adsorption zone.

[0048] The method of the present invention can increase production by increasing the number of repeating areas or resin tower tree patterns in certain areas.

[0049] The present invention will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed by the present invention.

[0050] Example 1

[0051] This embodiment provides a continuous ion exchange desalination system, including an adsorption zone, an elution zone, an alkali regeneration / activation zone, a water washing alkali removal zone, an acid regeneration zone, a water washing acid removal zone, and a reverse dilution zone; wherein, the adsorption zone, the elution zone, and the alkali regeneration / activation zone are arranged sequentially, the acid regeneration zone, the water washing acid removal zone, and the reverse dilution zone are arranged sequentially, and the water washing alkali removal zone is arranged adjacent to the acid regeneration zone and the reverse dilution zone, respectively;

[0052] The adsorption zone, elution zone, alkali regeneration / activation zone, water washing alkali removal zone, and de-dilution zone each include at least one set of ion exchange devices. Each set of ion exchange devices includes a cation exchange device and an anion exchange device connected in series. The cation exchange device is filled with cation exchange resin, which is at least one of D001 resin, 001X7 resin, and LX-160 resin. The anion exchange device is filled with anion exchange resin, which is at least one of D301 resin, LX-6703 resin, and LX-67 resin. The acid regeneration zone and the water washing acid removal zone each include only cation exchange devices. The water washing alkali removal zone includes a first water washing alkali removal zone and a second water washing alkali removal zone. The first water washing alkali removal zone is adjacent to the acid regeneration zone, and the second water washing alkali removal zone is adjacent to the de-dilution zone. The first water washing alkali removal zone includes at least one set of the ion exchange devices, and the second water washing alkali removal zone includes only anion exchange devices. The number of anion exchange devices in the second water washing and alkali removal zone is the same as the sum of the number of cation exchange devices in the acid regeneration zone and the water washing and acid removal zone.

[0053] Each group of ion exchange devices further includes a first feed valve and a first discharge valve. The cation exchange devices in the acid regeneration zone and the water washing deacidification zone each include a second feed valve and a second discharge valve. By switching the first feed valve, the first discharge valve, the second feed valve, and the second discharge valve, each cation exchange device completes the adsorption, elution, activation, regeneration, and de-dilution process in one process cycle, and each anion exchange device completes the adsorption, elution, regeneration, and de-dilution process in one process cycle.

[0054] Example 2

[0055] like Figure 1 As shown, taking inulin production as an example, this embodiment provides a continuous ion exchange desalination system, including an adsorption zone, an elution zone, an alkali regeneration / activation zone, a water washing alkali removal zone, an acid regeneration zone, a water washing acid removal zone, and a reverse dilution zone; wherein, the adsorption zone, the elution zone, and the alkali regeneration / activation zone are arranged sequentially, the acid regeneration zone, the water washing acid removal zone, and the reverse dilution zone are arranged sequentially, and the water washing alkali removal zone is adjacent to the acid regeneration zone and the reverse dilution zone respectively; the adsorption zone includes a No. 1 cation exchange resin tower, a No. 1 anion exchange resin tower, a No. 2 cation exchange resin tower, and a No. 2 anion exchange resin tower, and the elution zone includes a No. 11 cation exchange resin tower, Anion exchange resin tower No. 12, cation exchange resin tower and The anion exchange resin tower is divided into four zones: Alkali regeneration / activation zone (including cation exchange resin towers 9, 9, 10, and 10); water washing and alkali removal zone 1 (including cation exchange resin towers 8 and 8); acid regeneration zone (including cation exchange resin towers 6 and 7); water washing and acid removal zone (including cation exchange resin towers 4 and 5); water washing and alkali removal zone 2 (including anion exchange resin towers 4, 5, 6, and 7); and reverse dilution zone (including cation exchange resin tower 3 and 3).

[0056] Each group of ion exchange devices further includes a first feed valve and a first discharge valve. The cation exchange devices in the acid regeneration zone and the water washing deacidification zone each include a second feed valve and a second discharge valve. By switching the first feed valve, the first discharge valve, the second feed valve, and the second discharge valve, each cation exchange device completes the adsorption, elution, activation, regeneration, and de-dilution process in one process cycle, and each anion exchange device completes the adsorption, elution, regeneration, and de-dilution process in one process cycle.

[0057] Taking inulin production as an example, this embodiment provides a continuous ion exchange desalination method, including the following steps:

[0058] The feed solution, eluent, and regenerated solution enter different resin towers simultaneously through their respective feed manifolds, completing adsorption, elution, regeneration, and back-dilution steps in the different resin towers. The system operates continuously for 24 hours, with a switching time of 2 hours, an operating temperature of 25°C, and an operating pressure of 0.3 MPa. The cation exchange device is filled with D001 resin, and the anion exchange device is filled with LX-6703 resin.

[0059] (1) The inulin solution (sugar content 6-7 Brix, conductivity 3000μs / cm-6000μs / cm, temperature 25℃, water-soluble inorganic salt content 2000mg / L-4000mg / L, phenolic compound content 10mg / L-30mg / L, protein content 5mg / L-20mg / L, ester compound content 5-10mg / L, outlet conductivity requirement below 20μs / cm) enters from the top of the No. 1 cation exchange resin tower at the flow rate shown in Table 1. The flow rate is 6 BV / h. The lower part of the feed enters the No. 1 anion exchange resin tower, the No. 2 cation exchange resin tower, and the No. 2 anion exchange resin tower in sequence through a series valve. After 2 hours, the resin in the ion exchange adsorption tower reaches saturation. The desalted feed solution enters the adsorption product buffer tank through the lower part of the No. 2 anion exchange resin tower. The content of water-soluble inorganic salts in the desalted feed solution is 2 mg / L-18 mg / L, the content of phenolic compounds is 1 mg / L-5 mg / L, the content of protein is 1 mg / L-5 mg / L, and the content of ester compounds is 1 mg / L-5 mg / L.

[0060] (2) Pure water enters from the top of cation exchange resin tower No. 11 at a flow rate of 2 BV / h, and then... Anion exchange resin tower No. 12, cation exchange resin tower and The anion exchange resin tower undergoes forward water washing. Water from the washing tank passes through the tower to clean it, and the effluent from the washing tank enters the adsorption stock solution tank.

[0061] (3) A 1.5 mol / L sodium hydroxide aqueous solution is introduced from the top of the No. 9 cation exchange resin tower at a flow rate of 2 BV / h. The solution is then passed through the No. 9, No. 10, and No. 10 anion exchange resin towers for alkali regeneration. The tail liquid is discharged from the bottom of the No. 10 anion exchange resin tower to the neutralization tank. This process replaces the anions in the resin channels of the anion exchange resin tower with hydroxide ions, thereby activating the cation exchange resin tower and increasing the adsorption activity and stability of the resin. The molar ratio of anions in the inulin solution to alkali in the alkaline reagent is 1:1.05.

[0062] (4) Pure water enters from the top of the No. 8 cation resin tower at a flow rate of 2 BV / h, passes through the No. 8 anion resin tower, and recovers alkali from the bottom of the No. 8 anion resin tower, replacing the alkali solution in the resin tower with water.

[0063] (5) 1.5 mol / L hydrochloric acid is introduced into cation exchange resin tower No. 6 and cation exchange resin tower No. 7 for acid regeneration process. The flow rate is 2 BV / h. The tail liquid is discharged from the bottom of cation exchange resin tower No. 7 to the neutralization tank to replace the cations in the resin channels with hydrogen form. The molar ratio of cations in the inulin solution to acid in the acidic reagent is 1:1.02.

[0064] (6) Pure water enters from the top of the No. 4 anion exchange resin tower at a flow rate of 2 BV / h, passes through the No. 5, No. 6 and No. 7 anion exchange resin towers, and is recovered from the bottom of the No. 7 anion exchange resin tower to replace the alkaline solution in the resin tower.

[0065] (7) Pure water enters from the top of the No. 4 cation resin tower at a flow rate of 2 BV / h, passes through the No. 5 cation resin tower, and recovers acid from the bottom of the No. 5 cation resin tower, replacing the acid in the resin tower with water.

[0066] (8) The desalted liquid is fed into the No. 3 anion exchange resin tower from the bottom at a flow rate of 2 BV / h. It is then back diluted in the No. 3 cation exchange resin tower. The desalted liquid replaces the water in the resin tower to ensure that the concentration of the next feed does not change.

[0067] Comparative Example 1

[0068] Taking inulin production as an example, this comparative example provides an ion exchange desalination method, including the following steps:

[0069] The cation exchange unit is filled with DO1 resin. The cation column operation process steps are as follows:

[0070] (1) Adsorption: Inulin liquid delivered from outside (flow rate 21 m³ / h) 3 / h, sugar content 6brix-7brix, conductivity 3000μs / cm-6000μs / cm, temperature 25℃; outlet specification requirement conductivity below 20μs / cm) enters from the top of No.1 cation exchange resin tower at the flow rate shown in Table 1, enters No.2 cation exchange resin tower through a series valve at the bottom, and exits from the bottom of No.2 cation exchange resin tower.

[0071] (2) Eluting of cation resin tower: After 2 hours, the resin in the ion exchange adsorption tower reaches saturation. Pure water enters from the top of cation resin tower No. 11 and exits from cation resin tower No. 12 for forward water washing. The rinsing outlet liquid enters the adsorption stock tank.

[0072] (3) Activation of cation resin tower: 1.5 mol / L sodium hydroxide solution enters from the top of cation resin tower No. 9 and undergoes alkaline activation process through cation resin tower No. 10. The tail liquid is discharged from the bottom of cation resin tower No. 10 to the neutralization tank.

[0073] (4) Water washing to remove alkali from cation resin tower: Pure water enters from the top of No. 8 cation resin tower and is discharged from the bottom of the tower to recover alkali, replacing the alkali solution in the resin tower with water.

[0074] (5) Regeneration of cation resin towers: 1.5 mol / L hydrochloric acid is introduced into cation resin towers No. 6 and No. 7 for acid regeneration. The tail liquid is discharged from the bottom of cation resin tower No. 7 to the neutralization tank to replace the cations in the resin channels with hydrogen form.

[0075] (6) Acid removal by washing of cation resin tower: Pure water enters from the top of cation resin tower No. 4 and is discharged from the bottom of cation resin tower No. 5 for recycling, replacing the acid in the resin tower.

[0076] (7) Back dilution of cation resin tower: The feed liquid obtained from cation resin tower No. 2 is fed into cation resin tower No. 3 from the bottom and collected from the top of cation resin tower No. 3. The water in the resin tower is replaced by the finished product to ensure that the concentration of the next feed does not change.

[0077] The anion exchanger is filled with LX6703 resin. The anion column operation process steps are as follows:

[0078] (1) Adsorption: The feed liquid obtained from the No. 2 cation resin tower enters from the top of the No. 1 anion resin tower and enters the No. 2 anion resin tower through the series valve at the bottom. The finished product is obtained from the bottom of the No. 2 anion resin tower.

[0079] (2) Elution from the anion exchange resin tower: After 2 hours, the resin in the ion exchange adsorption tower reaches saturation, and pure water is then eluted from the tower. Entering from the top of the anion exchange resin column, from... The solution discharged from the No. 1 anion exchange resin tower undergoes forward water washing, and the effluent from the washing outlet enters the adsorption stock tank.

[0080] (3) Anion exchange resin tower regeneration: 1.5 mol / L sodium hydroxide solution alkali enters from the top of anion exchange resin tower No. 9 and undergoes alkali regeneration through anion exchange resin tower No. 10. The tail liquid is discharged from the bottom of anion exchange resin tower No. 10 to the neutralization tank.

[0081] (4) Washing alkali with water in anion exchange resin towers: Pure water enters from the top of anion exchange resin tower No. 4, passes through anion exchange resin towers No. 5, No. 6, No. 7, and No. 8, and is discharged from the bottom of anion exchange resin tower No. 8 to recover alkali, replacing the alkali solution in the resin tower with water.

[0082] (5) Back dilution of anion exchange resin tower: The liquid obtained from the bottom of the No. 2 anion exchange resin tower enters the No. 3 anion exchange resin tower from the bottom and is collected from the top of the No. 3 anion exchange resin tower. The finished product is used to replace the water in the resin tower to ensure that the concentration of the next feed does not change.

[0083] Comparative Example 2

[0084] Taking the production of inulin as an example, this comparative example provides an ion exchange desalination method, which is basically the same as the steps in Example 2, except that the alkali regeneration / activation zone includes anion exchange resin tower No. 9 and anion exchange resin tower No. 10.

[0085] Experimental Example

[0086] The desalinated products obtained in the above embodiments were tested for pH and conductivity, and the results are shown in the table below.

[0087] Table 1 Comparison of the treatment effects of two continuous separation schemes

[0088]

[0089]

[0090] As shown in the table above, compared with Example 1, the conductivity of the finished product obtained in Comparative Example 1 was worse at different volumes. The cation exchange resin was contaminated with organic matter such as proteins, polyphenols, and esters. Comparative Example 2 did not undergo an alkali activation step, and therefore could not remove organic matter such as proteins, polyphenols, and esters from the cation exchange resin, affecting the adsorption capacity of subsequent resins.

[0091] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A continuous ion exchange system, characterized in that, The continuous ion exchange system includes an adsorption zone, an elution zone, an alkali regeneration / activation zone, a water washing alkali removal zone, an acid regeneration zone, a water washing acid removal zone, and a reverse dilution zone; wherein: The adsorption zone, the elution zone, and the alkali regeneration / activation zone are arranged in sequence, and the acid regeneration zone, the water washing acid removal zone, and the reverse dilution zone are arranged in sequence. The water washing alkali removal zone is arranged adjacent to the acid regeneration zone and the reverse dilution zone, respectively. The adsorption zone, the elution zone, the alkali regeneration / activation zone, the water washing alkali removal zone, and the reverse dilution zone each include at least one set of ion exchange devices, and each set of ion exchange devices includes a cation exchange device and an anion exchange device connected in series; the acid regeneration zone and the water washing acid removal zone each include only cation exchange devices. Each group of ion exchange devices further includes a first feed valve and a first discharge valve. The cation exchange devices in the acid regeneration zone and the water washing deacidification zone each include a second feed valve and a second discharge valve. By switching the first feed valve, the first discharge valve, the second feed valve, and the second discharge valve, each cation exchange device completes the adsorption, elution, activation, regeneration, and de-dilution process in one process cycle, and each anion exchange device completes the adsorption, elution, regeneration, and de-dilution process in one process cycle. The water washing and alkali removal zone includes a water washing and alkali removal zone one and a water washing and alkali removal zone two. The water washing and alkali removal zone one is adjacent to the acid regeneration zone, and the water washing and alkali removal zone two is adjacent to the anti-dilution zone. The first zone for water washing and alkali removal includes at least one set of the aforementioned ion exchange devices, while the second zone for water washing and alkali removal includes only anion exchange devices.

2. The continuous ion exchange system according to claim 1, characterized in that, The number of anion exchange devices in the second water washing and alkali removal zone is the same as the sum of the number of cation exchange devices in the acid regeneration zone and the water washing and acid removal zone.

3. The continuous ion exchange system according to claim 1 or 2, characterized in that, The cation exchange device is filled with cation exchange resin, which is at least one of D001 resin, 001X7 resin, and LX-160 resin. And / or, the anion exchange device is filled with anion exchange resin, wherein the anion exchange resin is at least one of D301 resin, LX-6703 resin, and LX-67 resin.

4. A continuous ion exchange desalination method, characterized in that, The continuous ion exchange system according to any one of claims 1-3 is used; the continuous ion exchange desalination method includes the following steps: Obtain a desalination solution containing water-soluble inorganic salts, as well as at least one of phenolic compounds, proteins, and ester compounds; The desalted liquid is continuously introduced into the inlet of the adsorption zone of the continuous ion exchange system, and the desalted liquid is collected at the outlet of the adsorption zone. By switching valves, each cation exchanger in the continuous ion exchange system completes the adsorption, elution, activation, regeneration, and de-dilution process in one process cycle, and each anion exchanger in the continuous ion exchange system completes the adsorption, elution, regeneration, and de-dilution process in one process cycle.

5. The continuous ion exchange desalination method according to claim 4, characterized in that, The adsorption flow rate is 6 BV / h-10 BV / h; And / or, the elution flow rate is 2 BV / h-3 BV / h; And / or, the flow rate of the alkali regeneration / activation is 1 BV / h-2 BV / h; And / or, the flow rate of the water washing for alkali removal is 2BV / h-3BV / h; And / or, the acid regeneration flow rate is 1 BV / h-2 BV / h; And / or, the flow rate of the water washing to remove acid is 2 BV / h-3 BV / h; And / or, the flow rate of the reverse dilution is 2 BV / h-3 BV / h.

6. The continuous ion exchange desalination method according to claim 4, characterized in that, The alkaline reagent used in the alkali regeneration / activation zone is an aqueous solution of at least one of sodium hydroxide and lithium hydroxide, with an alkali concentration of 1 mol / L to 1.5 mol / L; And / or, the acidic reagent used in the acid regeneration zone is an aqueous solution of at least one of sulfuric acid and hydrochloric acid, with an acid concentration of 1 mol / L to 1.5 mol / L; And / or, the eluent used in the elution zone, the water washing de-alkali zone, and the water washing de-acid zone is pure water; And / or, the reagent used in the anti-dilution zone is the adsorbed and desalted feed solution.

7. The continuous ion exchange desalination method according to claim 6, characterized in that, The content of water-soluble inorganic salts in the desalination solution is 1200 mg / L-4000 mg / L; And / or, the content of phenolic compounds is 10 mg / L-50 mg / L; And / or, the protein content is 5 mg / L-20 mg / L; And / or, the content of ester compounds is 5 mg / L-10 mg / L; And / or, the molar ratio of anions in the desalination solution to alkali in the alkaline reagent is 1:1.03-1.05; And / or, the molar ratio of cations in the desalting solution to acids in the acidic reagent is 1:1.01-1.

02.

8. The continuous ion exchange desalination method according to claim 4, characterized in that, The interval between each switch is 10-120 minutes, the operating temperature is 10℃-40℃, and the operating pressure is 0.2MPa-0.4MPa.

9. The application of the continuous ion exchange desalination method according to any one of claims 4-8 in wastewater treatment, inulin preparation, and plant extraction.

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