Method for preventing double-chamber floating cation bed regenerated calcium sulfate from scaling

Abstract

The invention discloses a method for preventing calcium sulfate regenerated by a double-chamber floating cation bed from scaling, and belongs to the technical field of ion exchange desalting treatment for sulfuric acid regeneration. A dilution water distribution device is arranged at the top of a lower chamber of the double-chamber floating cation bed; the dilution water distribution device is connected with external pressure demineralized water; and demineralized water sprayed by the dilution water distribution device is used for further diluting a dilute sulfuric acid solution flowing into the lower chamber from top to bottom. The dilution water distribution device is arranged at the top of the lower chamber, dilution water is only added to the lower chamber, the regenerated acid concentration of the upper chamber is not changed, the consumed demineralized water amount is small, the regeneration time is short, meanwhile, water inlet of the dilution water device is independent of an original regenerated water pipe, control over the acid concentration of the lower chamber is flexible, and the regeneration time is short. Therefore, the purpose of obviously controlling the risk of calcium sulfate crystallization, precipitation and scaling of the double-chamber floating cation bed for sulfuric acid regeneration is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of ion exchange desalination treatment for sulfuric acid regeneration, in particular to a method for preventing scaling of calcium sulfate in double-chamber floating cationic bed regeneration. Background Art

[0002] The ion exchange resin method for producing demineralized water is a commonly used demineralized water production technology in the chemical and power industries. Especially when the output of demineralized water is large and the salt content of the raw water is 500 mg / L or less, the comprehensive investment and operating costs of this technology are significantly lower than those of membrane methods represented by ultrafiltration and reverse osmosis. Therefore, this technology is still widely used in the industrial field of demineralized water treatment. The ion exchange method uses equipment including cation exchangers, anion exchangers, and mixed ion exchangers. During the water treatment process, the ion exchanger undergoes an intermittent working mode of "normal operation water production" → "acid or alkali regeneration" → "normal operation water production" → "acid or alkali regeneration". Cation exchangers are usually regenerated with hydrochloric acid or sulfuric acid. Affected by the supply of acid, some projects use sulfuric acid regeneration.

[0003] Double room floating bed (such as Figure 3 (shown) is a type of cation exchanger, which has the following characteristics: the operating filtration rate (30~50m / h) is relatively high, which is greater than the fixed bed operating filtration rate (20~30m / h); during normal operation of water production, the water flows from bottom to top, and the resin is in a floating state in the bed. The bed is divided into two chambers, the lower chamber is filled with weak acid cation exchange resin, which mainly removes calcium and magnesium ions in temporary hardness; the upper chamber is filled with strong acid cation exchange resin, which mainly removes calcium and magnesium ions in permanent hardness and other cations such as sodium, potassium, and ammonium; during acid regeneration, the acid is mixed with clean water to form a dilute acid solution, which flows from top to bottom, displacing the cations in the upper and lower chambers in turn, forming wastewater for discharge.

[0004] During the regeneration of the double-chamber floating cationic bed using sulfuric acid, the dilute acid solution contains a large amount of sulfate ions, which flow from the upper chamber to the lower chamber. The upper chamber resin contains fewer calcium ions, which are not prone to calcium sulfate crystallization, precipitation and scaling problems. However, the lower chamber resin contains more calcium ions, which are replaced by hydrogen ions in the acid and are more likely to combine with sulfate to form calcium sulfate crystals. The higher the resin layer in the lower chamber, the longer the time it takes to flow through the resin layer, and the more likely it is that precipitation and scaling will occur inside the resin layer.

[0005] Calcium sulfate is slightly soluble in water, and its solubility in static water at room temperature is about 2560 mg / L. In the flowing solution where chemical reactions occur, calcium sulfate can exist as supersaturated non-crystallized precipitation, which is higher than its solubility in static water. This is because the crystallization precipitation process requires a certain amount of time. The greater the degree of supersaturation, the shorter the time, and vice versa. The usual sulfuric acid regeneration is divided into a three-step concentration method, and the concentration increases once. The sulfuric acid concentrations in the second and third steps are 3.0% and 5.0% respectively. During the regeneration process, the calcium sulfate concentration in the bottom layer of the double-chamber floating cation bed will be in a severely supersaturated state. Once the regeneration process is unexpectedly suspended or interrupted, the sulfuric acid regeneration liquid in the weak acid cation exchange resin layer is stationary, and a large amount of calcium sulfate precipitation will be formed. In order to prevent the supersaturated calcium sulfate from crystallizing and precipitating in the micropores of the weak acid cation exchange resin, blocking the pores of the weak acid cation exchange resin, blocking the regeneration of the weak acid cation exchange resin, and causing the weak acid cation exchange resin to be scrapped, measures should be taken to control the supersaturation of calcium sulfate.

[0006] In view of this, the present invention proposes a method for preventing scaling of calcium sulfate in a double-chamber floating cationic bed regeneration. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a method for preventing scaling of calcium sulfate in a double-chamber floating cationic bed regeneration. By arranging a dilution water distribution device on the top of the lower chamber, only dilution water is added in the lower chamber, and the regenerated acid concentration in the upper chamber remains unchanged, the amount of desalted water consumed is small, and the regeneration time is short. At the same time, since the water inlet of the arranged dilution water device is independent of the original regeneration water pipe, the control of the acid concentration in the lower chamber is flexible, thereby achieving the purpose of significantly controlling the risk of calcium sulfate crystallization, precipitation, and scaling of the double-chamber floating cationic bed for sulfuric acid regeneration.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is: A method for preventing scaling of calcium sulfate in a double-chamber floating cationic bed regeneration, characterized in that: a dilution water distribution device is arranged on the top of the lower chamber of the double-chamber floating cationic bed; the dilution water distribution device is connected to external pressurized desalted water; the desalted water sprayed by the dilution water distribution device is used to further dilute the dilute sulfuric acid solution flowing from top to bottom into the lower chamber.

[0009] A further improvement of the technical solution of the present invention is that the dilution water distribution device is made of a metal material with corrosion resistance not less than that of S31603 stainless steel.

[0010] A further improvement of the technical solution of the present invention is that the dilution water distribution device is arranged below the second porous water cap plate separating the upper chamber and the lower chamber.

[0011] A further improvement of the technical solution of the present invention is that the support and suspension method of the dilution water distribution device is as follows: a hanger rooting point is pre-fabricated below the second porous water cap plate between the upper chamber and the lower chamber, and the hanger is made of U-bolts and angle steels made of metal materials with corrosion resistance not lower than S31603 stainless steel; the number and distribution positions of the hangers are determined according to the size and load of the dilution water distribution device.

[0012] A further improvement of the technical solution of the present invention is that the dilution water distribution device includes a water distribution main pipe for connecting external pressurized desalted water and a plurality of water distribution branch pipes evenly arranged on both sides of the water distribution main pipe for spraying desalted water downward; one end of the water distribution main pipe is extended to the outside of the tank body of the double-chamber floating positive bed for connecting an external desalted water pipe; the water distribution branch pipes are evenly distributed on the cross-section of the tank body.

[0013] A further improvement of the technical solution of the present invention is that: a four-way pipe is arranged on the water distribution main pipe, and is connected to the water distribution branch pipe by threaded connection; the water distribution branch pipe is made of wire winding or densely opened.

[0014] The further improvement of the technical solution of the present invention is that: the diameter of the water distribution main pipe is DN80~DN150; the diameter of the water distribution branch pipe is DN25~DN65; the size of the wire winding gap or opening is not greater than 0.3mm.

[0015] A further improvement of the technical solution of the present invention is that: when the water distribution branch pipe is made of wire winding, each water distribution branch pipe, except for the end, is a wire winding structure; the end of the water distribution branch pipe is a seamless threaded pipe; the wire winding part of the water distribution branch pipe is welded and connected to the end; the end not connected to another water distribution branch pipe is a seamless pipe cap.

[0016] A further improvement of the technical solution of the present invention is that different water distribution branch pipes are connected by elbows and crosses; the elbows and the crosses are both seamless components, and the ends of the elbows and the crosses are both threaded interfaces.

[0017] The further improvement of the technical solution of the present invention is that: the desalted water pipe connected to the water distribution main pipe is independent of the original regenerated water pipe; the flow rate of the desalted water connected to the water distribution main pipe is 20~100m 3 / h, the pressure does not exceed 0.3MPa.

[0018] Due to the adoption of the above technical solution, the technical progress achieved by the present invention is: 1. The present invention sets a dilution water distribution device in the lower chamber of the double-chamber floating cationic bed to specifically dilute the sulfuric acid regeneration liquid in the lower chamber, reduce the concentration of calcium sulfate, control the scaling risk of calcium sulfate in the lower chamber, and protect the resin in the lower chamber in a simple, convenient and reliable method. It improves the regeneration safety and reliability of the double-chamber floating cationic bed system for sulfuric acid regeneration, extends the service life of the weak acid cation exchange resin in the lower chamber, and overcomes the risk and hidden danger problems that occur during the application of the prior art.

[0019] 2. The present invention arranges a dilution water distribution device in the lower chamber of the double-chamber floating cationic bed to control the scaling risk of calcium sulfate of the weak acid cation exchange resin in the lower chamber, thereby protecting the weak acid cation exchange resin in the lower chamber without affecting the regeneration effect of the strong acid cation resin in the upper chamber.

[0020] 3. The present invention only sets a dilution water distribution device in the lower chamber of the double-chamber floating cationic bed, thereby reducing the consumption of regenerated concentrated sulfuric acid, reducing the consumption of desalted water in the regeneration process, and shortening the regeneration time of the double-chamber floating cationic bed. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are 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 based on these drawings without creative labor. Figure 1 It is a schematic diagram of the internal elevation structure of a double-chamber floating cationic bed provided with a dilution water distribution device provided in an embodiment of the present invention; Figure 2 is a top view of the AA section of the dilution water distribution device provided in an embodiment of the present invention; Figure 3 It is a schematic diagram of the internal elevation structure of the double-chamber floating sunbed described in the background technology of the present invention; Among them, 1. regenerated dilute acid liquid inlet; 2. upper chamber; 2-1. first porous water cap plate; 2-2. strong acid cation exchange resin layer; 2-3. second porous water cap plate; 3. lower chamber; 3-1. weak acid cation exchange resin layer; 3-2. third porous water cap plate; 4. regenerated waste liquid outlet; 5. diluted water distribution device; 5-1. water distribution main pipe; 5-2. water distribution branch pipe. DETAILED DESCRIPTION

[0022] It should be noted that the terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or apparatus.

[0023] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0024] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "several" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0025] The present invention is further described in detail below with reference to the accompanying drawings and embodiments: like Figure 1 As shown, a method for preventing scaling of calcium sulfate in double-chamber floating cation bed regeneration is provided, wherein a dilution water distribution device 5 is arranged on the top of the lower chamber 3 of the double-chamber floating cation bed; the dilution water distribution device 5 is connected to external pressurized desalted water; the desalted water sprayed by the dilution water distribution device 5 is used to further dilute the dilute sulfuric acid solution flowing from top to bottom into the lower chamber 3. The concentration of calcium sulfate in the lower chamber 3 can be reduced, thereby controlling the risk of calcium sulfate crystallization, precipitation and scaling in the lower chamber 3, and protecting the weak acid cation exchange resin layer 3-1 in the lower chamber 3.

[0026] Specifically, Figure 1As shown, a U-shaped tubular regeneration dilute acid liquid inlet 1 for regeneration dilute acid liquid to enter is arranged at the top of the double-chamber floating cation bed tank body, and an inverted U-shaped tubular regeneration waste liquid outlet 4 for regeneration waste liquid to be extracted is arranged at the lower end, an upper chamber 2 and a lower chamber 3 are arranged in the tank body, a first porous water cap plate 2-1 is arranged at the top of the upper chamber 2, a second porous water cap plate 2-3 is arranged at the bottom end of the upper chamber 2, and a strong acid cation exchange resin layer 2-2 is arranged between the first porous water cap plate 2-1 and the second porous water cap plate 2-3; The second porous water cap plate 2-3 separates the upper chamber 2 from the lower chamber 3, and a third porous water cap plate 3-2 is arranged at the bottom of the lower chamber 3, and a weak acid cation exchange resin layer 3-1 is arranged between the second porous water cap plate 2-3 and the third porous water cap plate 3-2; when the double-chamber floating cation bed is regenerated, the regenerated dilute acid liquid enters the tank body from the regenerated dilute acid liquid inlet 1 at the top of the tank body, and passes through the strong acid cation exchange resin layer 2-2 and the weak acid cation exchange resin layer 3-1 in turn, and the regenerated waste liquid is discharged through the regenerated waste liquid outlet 4 at the bottom. The dilution water distribution device 5 is located at the top of the lower chamber 3, and the desalted water is connected from the external regeneration water pump outlet pipe to dilute the acid liquid in the lower chamber 3 and reduce the calcium sulfate supersaturation. The flow rate of the dilution water is comprehensively selected according to the calcium sulfate supersaturation, the regeneration liquid flow rate or the calculated residence time of the regeneration liquid resin layer, and is adjusted and determined according to the actual effect during system debugging.

[0027] Furthermore, the dilution water distribution device 5 is made of S31603 stainless steel, or other metal materials with stronger corrosion resistance.

[0028] Furthermore, the dilution water distribution device 5 is arranged below the second porous water cap plate 2 - 3 separating the upper chamber 2 and the lower chamber 3 .

[0029] Furthermore, the support and suspension method of the dilution water distribution device 5 is: pre-fabricating a hanger rooting point below the second porous water cap plate 2-3 between the upper chamber 2 and the lower chamber 3, and making the hanger with U-bolts and angle steels made of metal materials with corrosion resistance not lower than S31603 stainless steel; the number and distribution positions of the hangers are determined according to the size and load of the dilution water distribution device 5.

[0030] Further, such as Figure 2 As shown, the dilution water distribution device 5 includes a water distribution main pipe 5-1 for connecting external pressurized desalted water and a plurality of water distribution branch pipes 5-2 evenly arranged on both sides of the water distribution main pipe 5-1 for spraying desalted water downward; one end of the water distribution main pipe 5-1 is extended to the outside of the tank body of the double-chamber floating cation bed for connecting external desalted water pipes; the water distribution branch pipes 5-2 are evenly distributed on the tank body cross section. The pipe diameters of the water distribution main pipe 5-1 and the water distribution branch pipes 5-2 can be determined by calculation according to the specifications of the ion exchanger to ensure uniform water distribution.

[0031] Furthermore, a four-way pipe is provided on the water distribution main pipe 5-1, and is connected to the water distribution branch pipe 5-2 by threading; the water distribution branch pipe 5-2 is made of wire winding or densely opened.

[0032] Furthermore, the diameter of the main water distribution pipe 5-1 is generally within the range of DN80~DN150, and the diameter of the branch water distribution pipe 5-2 is generally within the range of DN25~DN65; the size of the wire winding gap or opening is not greater than 0.3mm.

[0033] Specifically, no pores are formed on the water distribution main pipe 5-1, and the water distribution branch pipe 5-2 adopts a stainless steel wire-wound pipe, and the size of the wire-wound gap is set to be no greater than 0.3 mm, because the effective particle size of the resin (strong acid cation exchange resin layer 2-2 and weak acid cation exchange resin layer 3-1) in the double-chamber floating cation bed is ≥ 0.5 mm, and 0.3 mm can prevent the resin particles from passing through. Adjacent water distribution branch pipes 5-2 are connected by threads. The wire-wound stainless steel pipe can also be replaced by a stainless steel pipe with dense openings, that is, the water distribution branch pipe 5-2 (stainless steel wire-wound) of the dilution water distribution device 5 can be replaced by a stainless steel pipe with small holes, and the aperture of the small holes is no greater than 0.3 mm.

[0034] Furthermore, when the water distribution branch pipe 5-2 is made of wire winding, each water distribution branch pipe 5-2 is a wire winding structure except for the end; the end of the water distribution branch pipe 5-2 is a seamless threaded pipe; the wire winding part of the water distribution branch pipe 5-2 is welded and connected to the end; the end that is not connected to another water distribution branch pipe 5-2 is a seamless pipe cap.

[0035] Furthermore, different water distribution branch pipes 5-2 are connected by elbows and crosses; both the elbows and crosses are seamless components, and the ends of the elbows and crosses are threaded interfaces.

[0036] Furthermore, the desalted water pipe connected to the water distribution main 5-1 is independent of the original regenerated water pipe; the flow rate of the desalted water connected to the water distribution main 5-1 is generally 20~100m 3 / h, and the pressure does not exceed 0.3MPa.

[0037] like Figure 3 The working principle of the double-chamber floating cationic bed in the prior art shown is that the double-chamber floating cationic bed adopts three-step regeneration and the following control measures during the regeneration of sulfuric acid: (1) Reduce the concentration of dilute acid entering the upper chamber. Usually the concentration of dilute acid in the first step is 0.8%~1%. In order to control the risk of calcium sulfate scaling, it can be reduced to 0.6%.

[0038] (2) Increase the proportion of concentrated acid used in the first step. Usually, the proportion of concentrated acid used in the first step of the three-step regeneration is 1 / 3. In order to control the risk of calcium sulfate scaling, it can be increased to 1 / 2.

[0039] (3) Reduce the concentration of dilute acid entering the upper chamber in the second and third steps.

[0040] The above technical solution has the following disadvantages: (1) Calcium sulfate scaling can only be avoided by controlling the flow rate and concentration of the regeneration acid at the outlet of the regeneration pump, which has a high risk.

[0041] (2) The amount of desalted water used in the regeneration process increases significantly.

[0042] (3) The regeneration time is greatly increased.

[0043] (4) The ion exchange efficiency of the resin decreases at low concentrations, resulting in the consumption of concentrated acid in the entire regeneration process. The amount increased.

[0044] The present invention sets a dilution water distribution device in the lower chamber of the double-chamber floating cationic bed, specifically dilutes the sulfuric acid regeneration liquid in the lower chamber, reduces the concentration of calcium sulfate, controls the scaling risk of calcium sulfate in the lower chamber, and protects the simple, convenient and reliable method of the resin in the lower chamber, improves the regeneration safety and reliability of the double-chamber floating cationic bed system for sulfuric acid regeneration, prolongs the service life of the weak acid cation exchange resin in the lower chamber, and overcomes the risk hidden dangers in the application process of the prior art. At the same time, the adjustment of the acid concentration in the lower chamber is more flexible, and the scaling risk of calcium sulfate in the lower chamber is controlled.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preventing scaling of calcium sulfate in a double-chamber floating cationic bed regeneration, characterized in that: A dilution water distribution device (5) is arranged on the top of the lower chamber (3) of the double-chamber floating cationic bed; the dilution water distribution device (5) is connected to external pressurized desalted water; the desalted water sprayed by the dilution water distribution device (5) is used to further dilute the dilute sulfuric acid solution flowing from top to bottom into the lower chamber (3).

2. A method for preventing scaling of calcium sulfate in a double-chamber floating cationic bed according to claim 1, characterized in that: The dilution water distribution device (5) is made of a metal material with corrosion resistance not less than that of S31603 stainless steel.

3. A method for preventing scaling of calcium sulfate in a double-chamber floating cationic bed according to claim 1, characterized in that: The dilution water distribution device (5) is arranged below the second porous water cap plate (2-3) that separates the upper chamber (2) and the lower chamber (3).

4. A method for preventing scaling of calcium sulfate in a double-chamber floating cationic bed according to claim 3, characterized in that: The dilution water distribution device (5) is supported and suspended in the following manner: a hanger rooting point is prefabricated below the second porous water cap plate (2-3) between the upper chamber (2) and the lower chamber (3); and the hanger is made of U-bolts and angle steel made of a metal material with corrosion resistance not less than that of S31603 stainless steel; the number and distribution positions of the hangers are determined according to the size and load of the dilution water distribution device (5).

5. A method for preventing scaling of calcium sulfate in a double-chamber floating cationic bed according to claim 1, characterized in that: The dilution water distribution device (5) comprises a main water distribution pipe (5-1) for connecting external pressurized desalted water and a plurality of branch water distribution pipes (5-2) evenly arranged on both sides of the main water distribution pipe (5-1) for spraying desalted water downward; one end of the main water distribution pipe (5-1) is extended to the outside of the tank body of the double-chamber floating cation bed for connecting an external desalted water pipe; the branch water distribution pipes (5-2) are evenly distributed on the cross section of the tank body.

6. A method for preventing scaling of calcium sulfate in a double-chamber floating cationic bed according to claim 5, characterized in that: The water distribution main pipe (5-1) is provided with a four-way connection, which is threadedly connected to the water distribution branch pipe (5-2); the water distribution branch pipe (5-2) is made of wire winding or has dense holes.

7. A method for preventing scaling of calcium sulfate in a double-chamber floating cationic bed according to claim 6, characterized in that: The diameter of the water distribution main pipe (5-1) is DN80-DN150; the diameter of the water distribution branch pipe (5-2) is DN25-DN65; and the size of the wire winding gap or opening is not greater than 0.3 mm.

8. A method for preventing scaling of calcium sulfate in a double-chamber floating cationic bed according to claim 6, characterized in that: When the water distribution branch pipe (5-2) is made by wire winding, each water distribution branch pipe (5-2) is a wire winding structure except for the end; the end of the water distribution branch pipe (5-2) is a seamless threaded pipe; the wire winding part of the water distribution branch pipe (5-2) is welded and connected to the end; the end not connected to another water distribution branch pipe (5-2) is a seamless pipe cap.

9. A method for preventing scaling of calcium sulfate in a double-chamber floating cationic bed according to claim 5, characterized in that: Different water distribution branch pipes (5-2) are connected by elbows and crosses; the elbows and the crosses are both seamless components, and the ends of the elbows and the crosses are both threaded interfaces.

10. A method for preventing scaling of calcium sulfate in a double-chamber floating cationic bed according to claim 5, characterized in that: The desalted water pipe connected to the water distribution main pipe (5-1) is independent of the original regenerated water pipe; the flow rate of the desalted water connected to the water distribution main pipe (5-1) is 20~100m 3 / h, the pressure does not exceed 0.3MPa.

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