Method for evaluating mechanical strength of anion exchange resin in operation
By using acid solution treatment and debrine washing in the ion exchange column, the crushing strength is measured and the permeability reduction rate is calculated, and the complex problem of mechanical strength evaluation of anion exchange resins in the prior art is solved, and fast and accurate machinery is achieved Strength reduction assessment simplifies operational procedures.
Patent Information
- Application Number
- CN202411235331.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-04
- Publication Date
- 2024-12-13
AI Technical Summary
The prior art is difficult to effectively evaluate the degree of mechanical strength reduction of used anion exchange resins, especially in terms of permeability resistance, and the traditional method is complex to operate, making it difficult to quickly and accurately monitor changes in mechanical strength.
By placing the running and neoanion exchange resins in an ion exchange column, using acid solution for rapid transformation and desalination water, the crushing strength is determined and the permeability reduction rate is calculated, the acid-base alternation steps are simplified, and crushing is adopted The proportion of particles with strength <1 N/particle is used as an evaluation index.
It realizes a rapid and simple evaluation of the mechanical strength drop of anion exchange resin during operation, eliminates the steps of rolling, drying and separation, and provides a more accurate evaluation of the permeability change, which is easy to operate and highly guided. Advantages.
Smart Images
Figure SMS_1 
Figure SMS_2 
Figure SMS_3
Abstract
Description
Technical Field
[0001] The invention relates to the field of detection technology, and in particular to a method for evaluating the mechanical strength of an anion exchange resin in operation. Background Art
[0002] Ion exchange resins are widely used in feed water treatment systems and condensate polishing systems of power plants to remove ionic impurities in water through ion exchange. Ion exchange resins will gradually age during use, resulting in a decrease in mechanical strength and breakage, which poses a safety hazard to system operation. Since anion exchange resins have the characteristics of high transformation expansion rate, easy thermal degradation, and easy adsorption of pollutants such as organic matter, after a period of use, the degree of decrease in their mechanical strength is often much higher than that of cation exchange resins. Therefore, it is extremely necessary to conduct regular testing of the mechanical strength of anion exchange resins to understand the degree of decrease in the mechanical strength of anion exchange resins.
[0003] The mechanical strength of ion exchange resin can usually be evaluated by crushing strength, post-grinding roundness and infiltration roundness. Among them, crushing strength is the minimum pressure required for a single ion exchange resin particle to be crushed, reflecting the compressive resistance of the ion exchange resin. The post-grinding roundness is the pressure and friction applied to the ion exchange resin by the rotation of the ceramic balls and the rollers, so that the ion exchange resin with low strength or cracks is broken, reflecting the compressive resistance and wear resistance of the ion exchange resin. Compared with the determination process of the post-grinding roundness, the infiltration roundness has an additional acid-base alternating treatment step, which applies additional quantitative osmotic pressure and water flow impact to the ion exchange resin. Due to the quality differences between different ion exchange resins, the degree of damage to the ion exchange resin caused by the acid-base alternating treatment is different, resulting in differences in the infiltration roundness, which can be used to evaluate the permeability resistance of the ion exchange resin.
[0004] For ion exchange resins used in ion exchange systems, on the one hand, water flow impact, resin pressure difference, etc. may directly crush the resin, so it is necessary to examine the changes in the compressive resistance of the resin; on the other hand, the resin will undergo ion exchange during use, and the resin may also be damaged under the action of osmotic pressure, so it is also necessary to evaluate the changes in the resin's resistance to permeability. The difference in compressive resistance between new resins and operating resins can be better compared by measuring the crushing strength of new resins and operating resins. However, the introduction to the national standard GB12598-2023 states: "For used ion exchange resins, because they have been subjected to various external forces during use, the results of the infiltration and grinding ball rate or the post-grinding ball rate measured in accordance with this document may be low. Therefore, for used ion exchange resins, it is not suitable to measure the infiltration and grinding ball rate and the post-grinding ball rate in accordance with this document."
[0005] Therefore, the present invention proposes a method for evaluating the degree of decrease in mechanical strength of used anion exchange resin from the perspective of permeability resistance, which is used to monitor the rate of decrease in permeability resistance of the same anion exchange resin. The method has the advantages of simple operation and strong guidance, and is of great significance for actual production. Summary of the invention
[0006] In view of the above shortcomings of the prior art, the present invention provides a method for evaluating the mechanical strength of anion exchange resin in operation, which can more comprehensively and quickly evaluate the mechanical strength of anion exchange resin in operation from the perspective of permeability resistance.
[0007] To achieve the above purpose, the specific technical solutions of the present invention are as follows:
[0008] A method for evaluating the mechanical strength of an anion exchange resin in operation comprises the following steps:
[0009] (1) Take the anion exchange resin in operation and the new anion exchange resin that has not been put into use, and place them in the ion exchange column respectively;
[0010] (2) Use an acid solution to pass through the ion exchange column to cause the anion exchange resin to undergo rapid transformation;
[0011] (3) Use deionized water to pass through the ion exchange column to wash away the acid solution remaining in the anion exchange resin;
[0012] (4) Take out the anion exchange resins in operation and those not in operation from the ion exchange column, measure the crushing strength of the anion exchange resins respectively, calculate the percentage of particles with a crushing strength less than 1 N / particle, calculate the permeability resistance reduction rate, and evaluate the degree of mechanical strength reduction of the anion exchange resins in operation.
[0013] Preferably, in step (1), the amount of anion exchange resin taken is 15-30 mL.
[0014] Preferably, in step (1), the anion exchange resin in operation is an anion exchange resin that has been used in an ion exchange system for a period of time and regenerated into a hydroxide form by using a sodium hydroxide solution, and the new anion exchange resin that has not been put into use is a new anion exchange resin that has been converted into a hydroxide form by using a sodium hydroxide solution and has not yet been put into use; the hydroxide form rate of the anion exchange resin in operation or the new anion exchange resin that has not been put into use is 100%.
[0015] Preferably, in step (1), the ion exchange column is a plexiglass exchange column with a filter plate having an inner diameter of 18 mm and a height of 250 mm.
[0016] Preferably, in step (2), the specific operation of passing the acid solution through the ion exchange column is: first, the acid solution with a volume of 6 to 10 times the volume of the anion exchange resin is passed through the ion exchange column at a flow rate of 5 to 8 times the volume of the anion exchange resin per minute, and then the acid solution with a volume of 10 to 15 times the volume of the anion exchange resin is passed through the ion exchange column at a flow rate of 1 to 2 times the volume of the anion exchange resin per minute.
[0017] More preferably, the concentration of the acid solution is 1 mmol / mL.
[0018] More preferably, the acid solution is a hydrochloric acid solution.
[0019] Preferably, in step (3), the amount of deionized water used is 20 to 30 times the volume of the anion exchange resin, and the flow rate through the ion exchange column is 2 to 4 times the volume of the anion exchange resin per minute.
[0020] Preferably, in step (3), the completion of the anion exchange resin cleaning is indicated by the effluent from the ion exchange column being neutral.
[0021] Preferably, in step (4), the calculation method of the permeability resistance decrease rate δ is as follows:
[0022]
[0023] Wherein, η1 is the proportion of particles of anion exchange resin in operation with a crushing strength of less than 1 N / particle after acid treatment, and η2 is the proportion of particles of new anion exchange resin that has not been put into use with a crushing strength of less than 1 N / particle after acid treatment.
[0024] Preferably, in step (4), the crushing strength <1 N / particle means that the crushing strength of a single particle is less than the minimum detection limit of the instrument 1 N.
[0025] Preferably, in step (4), the crushing strength is determined by wet-sieving anion exchange resin of a specified particle size in water using a test sieve of a certain aperture, flushing the anion exchange resin stuck in the mesh with deionized water and collecting the anion exchange resin, and determining the crushing strength of the anion exchange resin using an automatic particle strength tester.
[0026] Further preferably, the automatic particle strength tester is used to measure the crushing strength of 30 to 50 anion exchange resin particles, and the proportion of particles with a crushing strength of less than 1 N / particle is counted.
[0027] Further preferably, the specific operation of measuring the crushing strength using the automatic particle strength tester is: starting and preheating the particle strength tester, sucking an anion exchange resin onto the test platform with a plastic straw, so that the anion exchange resin particles are located directly below the pressure head, starting the pressure head, and recording the pressure value displayed when the anion exchange resin particles are crushed.
[0028] The present invention uses a hydroxyl type anion exchange resin as a test object, and through acid treatment, it undergoes a rapid transformation, destroys it to a certain extent, and evaluates the change in the permeability resistance of the anion exchange resin after use. Based on the characteristics that the anion exchange resin in operation is in the form of hydroxyl type, and has been subjected to various external forces, and the permeability resistance is significantly reduced, the present invention regenerates the anion exchange resin to be tested into a hydroxyl type, uses an acid solution to simply treat it, measures the crushing strength value, and statistically calculates the proportion of particles with a crushing strength of <1 N / particle. The degree of decrease in the mechanical strength of the anion exchange resin after use is calculated to evaluate the change in the permeability resistance of the anion exchange resin. The ball rate after grinding is to grind the ion exchange resin with poor compressive resistance through the rolling process to distinguish the mechanical strength of the ion exchange resin. The present invention uses crushing strength to distinguish the difference in compressive resistance of the ion exchange resin after acid treatment. While simplifying the operation, it can more comprehensively and quickly evaluate the mechanical strength of the anion exchange resin in operation, which is of great significance for actual production.
[0029] Compared with the prior art, the present invention is beneficial in that:
[0030] (1) Based on the characteristics that the strength of anion exchange resins in operation generally decreases significantly and they are mainly in the hydroxide type, the present invention simplifies the acid-base alternation step into a one-step acid solution treatment. After treatment in the specific manner of the present invention, the degree of decrease in the mechanical strength of the anion exchange resin in operation can be evaluated from the perspective of penetration resistance by comparing the difference in the proportion of particles with a crushing strength of less than 1 N / particle between an unused new hydroxide type anion exchange resin and an hydroxide type anion exchange resin in operation after acid treatment.
[0031] (2) The present invention uses the proportion of particles with a crushing strength of less than 1 N / particle as an evaluation index of the mechanical strength of the anion exchange resin after acid treatment, and then calculates the permeability reduction rate δ. Compared with the determination of the ball rate after grinding and the ball rate of infiltration grinding, the present invention omits the steps of rolling, drying, and separation, and has the advantages of simple operation and strong guidance. DETAILED DESCRIPTION
[0032] The technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0033] The present invention provides a method for evaluating the mechanical strength of an anion exchange resin in operation, comprising the following steps:
[0034] (1) Take the anion exchange resin in operation and the new anion exchange resin that has not been put into use, and place them in the ion exchange column respectively;
[0035] (2) Use an acid solution to pass through the ion exchange column to cause the anion exchange resin to undergo rapid transformation;
[0036] (3) Use deionized water to pass through the ion exchange column to wash away the acid solution remaining in the anion exchange resin;
[0037] (4) Take out the anion exchange resins in operation and those not in operation from the ion exchange column, measure the crushing strength of the anion exchange resins respectively, calculate the percentage of particles with a crushing strength less than 1 N / particle, calculate the permeability resistance reduction rate, and evaluate the degree of mechanical strength reduction of the anion exchange resins in operation.
[0038] In some examples, in step (1), the amount of anion exchange resin taken is 15-30 mL.
[0039] In some examples, in step (2), the specific operation of the acid solution treatment is: first, an acid solution with a volume of 6 to 10 times the volume of the anion exchange resin is passed through the ion exchange column at a flow rate of 5 to 8 times the volume of the anion exchange resin per minute, and then an acid solution with a volume of 10 to 15 times the volume of the anion exchange resin is passed through the ion exchange column at a flow rate of 1 to 2 times the volume of the anion exchange resin per minute.
[0040] In some examples, in step (3), the amount of deionized water used is 20 to 30 times the volume of the anion exchange resin, and the flow rate through the ion exchange column is 2 to 4 times the volume of the anion exchange resin per minute.
[0041] In the following specific implementation example, in step (4), the calculation method of the permeability resistance decrease rate δ is as follows:
[0042]
[0043] Wherein, η1 is the proportion of particles of anion exchange resin in operation with a crushing strength of less than 1 N / particle after acid treatment, and η2 is the proportion of particles of new anion exchange resin that has not been put into use with a crushing strength of less than 1 N / particle after acid treatment.
[0044] Example 1
[0045] This implementation uses Brand A anion exchange resin (hereinafter referred to as old resin) after being used in the condensate polishing system for a period of time as the test object to evaluate the degree of decrease in its mechanical strength. The steps are as follows:
[0046] (1) Take 20 mL of the old resin regenerated to the hydroxyl form and the new anion exchange resin transformed to the hydroxyl form (hereinafter referred to as the new resin), and transfer them to a plexiglass exchange column with an inner diameter of 18 mm and a height of 250 mm and a filter plate. A separatory funnel is connected to the plexiglass exchange column;
[0047] (2) Add 150 mL of 1 mol / L hydrochloric acid to the separatory funnel and pass it through the exchange column at a flow rate of 100 mL / min; then add 250 mL of 1 mol / L hydrochloric acid to the separatory funnel and pass it through the ion exchange column at a flow rate of 25 mL / min to completely convert the anion exchange resin from the hydroxyl form to the chloride form;
[0048] (3) Use 500 mL of deionized water at a flow rate of 50 mL / min to pass through the ion exchange column to wash away the hydrochloric acid solution remaining in the anion exchange resin, and use methyl orange solution to confirm that the effluent is neutral;
[0049] (4) Take out the treated old resin and new resin, sieve them to obtain the old resin and new resin with a particle size of 0.63 mm, and wash off the resin with deionized water respectively; start and preheat the particle strength tester, use a plastic straw to suck one anion exchange resin onto the test platform, so that the anion exchange resin particle is directly under the pressure head, start the pressure head, record the pressure value displayed when the particle is broken, repeat the measurement of the crushing strength of 30 anion exchange resins, and count the proportion of old resin and new resin particles with a crushing strength of <1 N / particle. The results are shown in Table 1.
[0050] Table 1: Statistical results of the percentage of particles with a crushing strength of less than 1 N / particle in Example 1
[0051]
[0052] According to the data in Table 1, the permeability resistance reduction rate δ of the old resin in this embodiment is calculated to be 75%. It can be seen that the permeability resistance of the old resin in this embodiment is significantly reduced, and the probability of transformation and breakage during subsequent use is very high.
[0053] The inventors separately took 20 mL of the old resin and new resin in Example 1, treated them according to steps (1) to (3) in Example 1, and then tumbled, dried, and separated them according to the relevant operating steps of the ball rate after grinding in the national standard GB12598-2023, and calculated the ball rates of the new resin and the old resin after acid treatment. The results are shown in Table 2.
[0054] Table 2: Results of ball rate after acid treatment
[0055]
[0056] As can be seen from Table 2, the percentage of broken resin obtained by measuring the ball rate after grinding (the ball rates are 77.39% and 22.03%, respectively, and the broken rates are 22.61% and 77.97%, respectively) is basically the same as the percentage of particles with a crushing strength of less than 1 N / particle measured by the method of the present invention. Therefore, the present invention first performs a simple acid treatment on the resin, then measures its crushing strength, and uses the percentage of particles with a crushing strength of less than 1 N / particle as an evaluation index of the mechanical strength of the treated resin, eliminating the cumbersome steps of rolling, drying and separation, and obtaining a more accurate result, which can better evaluate the degree of decrease in the permeability resistance of the anion exchange resin.
[0057] Example 2
[0058] In this embodiment, Brand B anion exchange resin (old resin) after being used in a condensate polishing system for a period of time was used as the test object to evaluate the degree of reduction in its mechanical strength. The steps (1) to (4) described in Example 1 were performed to obtain the percentage of particles with a crushing strength of less than 1 N / particle of the new resin and the old resin after acid treatment. The results are shown in Table 3.
[0059] Table 3: Statistical results of the percentage of particles with crushing strength <1 N / particle in Example 2
[0060]
[0061] According to the data in Table 3, the permeability resistance reduction rate δ of the old resin in this embodiment is calculated to be 23.33%. It can be seen that the mechanical strength of the old resin in this embodiment has a low degree of reduction, and the possibility of transformation and breakage during subsequent operation is low.
[0062] In summary, the present invention uses a hydroxide type anion exchange resin as a test object, simplifies the acid-base alternation step into a one-step treatment step of an acid solution, and after treatment in a specific manner of the present invention, can compare the difference between an unused new hydroxide type anion exchange resin and an operating hydroxide type anion exchange resin, and then evaluate the change in the permeability resistance of the operating anion exchange resin. The present invention more comprehensively and quickly evaluates the mechanical strength of the operating anion exchange resin from the perspective of permeability resistance, which is of great significance for actual production. At the same time, the crushing strength is used to distinguish the difference in the compressive resistance of the resin after acid treatment, eliminating the steps of rolling, drying, separation, etc., and has the advantages of simple operation and strong guidance.
[0063] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.
Claims
1. A method for evaluating the mechanical strength of anion exchange resin in operation, It is characterized in that The following steps are involved: (1) Take the anion exchange resin in operation and the new anion exchange resin that has not been put into use, and place them in the ion exchange column respectively; (2) Use an acid solution to pass through the ion exchange column to cause the anion exchange resin to undergo rapid transformation; (3) Use deionized water to pass through the ion exchange column to wash away the acid solution remaining in the anion exchange resin; (4) Take out the anion exchange resin in operation and the new anion exchange resin that has not been put into use in the ion exchange column, measure the crushing strength respectively, and count the proportion of particles with a crushing strength of less than 1 N / particle; then calculate the permeability resistance decrease rate of the anion exchange resin in operation to evaluate the degree of decrease in its mechanical strength.
2. A method for evaluating the mechanical strength of an anion exchange resin in operation according to claim 1, It is characterized in that In step (1), the amount of anion exchange resin taken is 15-30 mL.
3. The method for evaluating the mechanical strength of an anion exchange resin in operation according to claim 1, It is characterized in that In step (1), the anion exchange resin in operation is an anion exchange resin that has been used in an ion exchange system for a period of time and regenerated into a hydroxide form by using a sodium hydroxide solution, and the new anion exchange resin that has not been put into use is an new anion exchange resin that has been transformed into a hydroxide form by using a sodium hydroxide solution and has not yet been put into use.
4. The method for evaluating the mechanical strength of an anion exchange resin in operation according to claim 1, It is characterized in that In step (2), the specific operation of passing the acid solution through the ion exchange column is: first, the acid solution with a volume of 6 to 10 times the volume of the anion exchange resin is passed through the ion exchange column at a flow rate of 5 to 8 times the volume of the anion exchange resin per minute, and then the acid solution with a volume of 10 to 15 times the volume of the anion exchange resin is passed through the ion exchange column at a flow rate of 1 to 2 times the volume of the anion exchange resin per minute.
5. The method for evaluating the mechanical strength of an anion exchange resin in operation according to claim 1, It is characterized in that In step (3), the amount of deionized water used is 20 to 30 times the volume of the anion exchange resin, and the flow rate through the ion exchange column is 2 to 4 times the volume of the anion exchange resin per minute.
6. The method for evaluating the mechanical strength of an anion exchange resin in operation according to claim 1, It is characterized in that In step (3), the sign that the anion exchange resin cleaning is completed is that the effluent from the ion exchange column is neutral.
7. The method for evaluating the mechanical strength of an anion exchange resin in operation according to claim 1, It is characterized in that In step (4), the calculation method of the permeability resistance decrease rate δ is as follows: ； Where η 1 is the percentage of anion exchange resin particles with a crushing strength of less than 1 N / particle after acid treatment during operation, η 2 It is the percentage of new anion exchange resin particles that have not been put into use and have a crushing strength of less than 1 N / particle after acid treatment.
8. The method for evaluating the mechanical strength of an anion exchange resin in operation according to claim 1, It is characterized in that In step (4), the crushing strength is determined by wet-sieving an anion exchange resin of a specified particle size in water using a test sieve of a certain aperture, flushing the anion exchange resin stuck in the mesh with deionized water and collecting the anion exchange resin, and determining the crushing strength of the anion exchange resin using an automatic particle strength tester.
9. The method for evaluating the mechanical strength of an anion exchange resin in operation according to claim 8, It is characterized in that The particle size of the anion exchange resin is selected based on the following criteria: the selected particle size is close to the average particle size of the anion exchange resin.
10. The method for evaluating the mechanical strength of an anion exchange resin in operation according to claim 8, It is characterized in that The automatic particle strength tester was used to measure the crushing strength of 30 to 50 anion exchange resin particles, and the percentage of particles with a crushing strength of less than 1 N / particle was counted.