Method for treating regeneration liquid of decalcification resin for sugarcane juice and method for decalcifying sugarcane juice

Abstract

The application provides a sugarcane juice decalcification resin regeneration liquid treatment method and a sugarcane juice decalcification method. The clear liquid obtained by treating the sugarcane juice decalcification resin regeneration liquid by a sodium carbonate chemical method is configured as a regeneration agent of the sugarcane juice decalcification resin. The sugarcane juice decalcification method removes calcium ions in the sugarcane juice by using continuous multi-column ion exchange resin columns, and the regeneration agent of the decalcification resin is repeatedly recycled by using the sodium chloride clear liquid obtained by treating the regeneration liquid by the sodium carbonate chemical method, so that the environmental protection treatment problem of the regeneration liquid is solved, the residual sodium chloride in the regeneration liquid can be fully utilized, and the input amount of the regeneration agent is reduced. The sodium chloride clear liquid obtained by excessively reacting the sodium carbonate with the calcium chloride in the regeneration liquid does not affect the regeneration work of the calcium saturated resin column, the adsorption effect of the resin is good after the regeneration, and the resin treatment capacity remains stable. The sodium carbonate chemical treatment process can realize the resource recycling of the regeneration liquid, reduces the discharge of wastewater in actual mass production, and reduces the industrial production cost.

Description

Technical Field

[0001] This invention relates to the field of sugar engineering technology, and in particular to a method for treating sugarcane juice decalcification resin regeneration solution and a method for decalcification of sugarcane juice. Background Technology

[0002] In the sugarcane refining process, the reaction between lime milk added during the sulfite clarification process and phosphoric acid / SO2 to form Ca3(PO4)2 and CaSO3 is incomplete, resulting in a high calcium ion content in the clarified juice, typically reaching 0.37%-0.56% (calcium oxide content in the solid solution of the clarified juice), or 400-600 mg / L (calcium ion content in the clarified juice). During subsequent evaporation and boiling, some calcium ions crystallize out as water evaporates, forming scale on the heating pipe walls and reducing heat transfer efficiency. Other calcium ions, suspended in the syrup, deposit in the granulated sugar crystals during crystallization, increasing the turbidity and ash content of the sugar. This increases energy consumption and affects product quality, remaining a major bottleneck for cost reduction and efficiency improvement in sulfite sugar mills.

[0003] Currently, ion exchange resin method is one of the commonly used methods for decalcification of sucrose. This method utilizes the selective adsorption of calcium ions by ion exchange resin to remove calcium ions from the sucrose solution, thereby achieving decalcification. However, as the decalcification process proceeds, the ion exchange resin gradually becomes saturated and loses its decalcification capacity. At this point, the resin needs to be regenerated to restore its adsorption performance. Existing sucrose decalcification resin regeneration processes have many problems. The main chemical method for resin regeneration—sodium chloride or alkaline sodium chloride solution regeneration—is simple to operate but consumes a lot of chemicals and suffers from problems such as difficult treatment of the regenerated solution or incomplete resin regeneration, which undoubtedly increases the production cost of sugarcane. These regenerators generate a large amount of wastewater during use, which contains high concentrations of salt and chemicals. Direct discharge of this wastewater would cause serious environmental pollution. In addition, some regeneration processes have unsatisfactory regeneration effects, with low recovery of the regenerated resin's exchange capacity, failing to meet the requirements of efficient decalcification and affecting the continuity and stability of sucrose production.

[0004] Among the published decalcification patents in China, Chinese patent CN202111235828.1 discloses a beet sugar decalcification system, using NaOH softened diluted juice as the regenerator; Chinese patent CN202410070515.2 discloses a sucrose decalcification method and system, where the decolorizing resin regenerator is a salt-alkali solution, specifically a mixed salt-alkali solution with a NaCl content of 9% and a NaOH content of 0.25%, and the decalcification ion exchange resin regenerator is a liquid obtained by neutralizing the regeneration solution of the decolorizing ion exchange resin with acid. This technology is mainly applied in the raw sugar refining process. Chinese patent CN00130871.8 discloses a regenerated liquid of an ion exchange resin for sugar decolorization and its regeneration method. It mainly uses CO2 saturation or the addition of phosphoric acid to precipitate calcium ions into calcium carbonate or calcium phosphate, which is then filtered and reused. Its main application is in sucrose decolorization. Chinese patent 201010571078.0 discloses a regeneration method for decolorizing and decalcifying resin in sugar refining and a method for reusing the regenerated liquid. The regenerator for the decolorizing resin is an alkaline brine solution, specifically a mixed salt solution of 120 g / L NaCl and 5 g / L NaOH. The regenerator for the decalcifying resin is the regenerated liquid containing pigments after decolorization. The regenerated liquid of the decalcifying resin is concentrated and dried to produce a salt-rich, calcium-rich pigment product. This method is still in the laboratory stage. Chinese patent CN202011016180.4 discloses a resource utilization system and process for resin regenerated liquid. This method uses nanofiltration and reverse osmosis technologies to treat the waste liquid before application.

[0005] It is evident that the patented technology for desalting and decolorizing sugar juice and syrup using ion exchange resin technology in China is mainly applied in the raw sugar refining process or the sugar production process of beets, based on the low concentration of calcium ions in the raw materials.

[0006] The raw material composition in the sugarcane sugar clarification process is relatively complex. The components of sugarcane juice and beet juice are different, and the residual calcium ion content in the raw materials during the production process is much higher than that of raw sugar or beet juice, which increases the technical difficulty of decalcification of sugarcane juice.

[0007] After using ion exchange resin for decolorization and decalcification, the resin regeneration process generates a large amount of regenerated liquid that cannot be treated. Currently, there are very few patent reports on the application of ion exchange resin for decolorization and decalcification in sugarcane sugar production, as well as on the treatment and recycling of resin regenerated liquid. The main concern is the environmental pollution problem caused by the regenerated liquid. Summary of the Invention

[0008] This invention primarily addresses the environmental pollution problem caused by the regenerated liquid after sugarcane juice decalcification. It provides a new regenerated liquid treatment process that generates virtually no waste liquid discharge, and the regenerated resin has a high degree of recovery in exchange capacity, meeting the requirements for efficient decalcification.

[0009] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0010] A method for treating sugarcane juice decalcification resin regeneration liquid involves using a sodium carbonate chemical treatment method to obtain a clarified liquid as a regenerator for sugarcane juice decalcification resin. Sugarcane juice decalcification resin regeneration liquid refers to the regeneration waste liquid formed after the decalcification resin has become saturated and a regenerator is added.

[0011] The chemical treatment method for sodium carbonate includes the following steps:

[0012] S1. After adding excess sodium carbonate to sugarcane juice decalcification resin regeneration solution and allowing it to react fully, a mixture of sodium chloride and calcium carbonate is obtained;

[0013] S2. Filtering a mixture of sodium chloride and calcium carbonate yields calcium carbonate precipitate and a clear liquid.

[0014] The method for preparing the regenerator for sugarcane juice decalcification resin is as follows: part of the clear liquid is used as a solid sodium chloride solvent to prepare a saturated sodium chloride solution; the remaining clear liquid is mixed with the saturated sodium chloride solution to prepare an 8%-10% sodium chloride regenerator.

[0015] When using the sodium carbonate chemical treatment method, the amount of sodium carbonate added is N times the amount of calcium ions in the regenerated solution, where N = 1.5-3.5. The reaction time is 10-40 minutes, and the reaction temperature is 30℃-60℃.

[0016] The pH of the regenerator solution is adjusted to 6.5-9.5.

[0017] The present invention also provides a method for decalcifying sugarcane juice, which uses a continuous multi-column ion exchange resin column to remove calcium ions from sugarcane juice, and the sugarcane juice decalcification resin regeneration solution is treated by the aforementioned treatment method.

[0018] The method for removing calcium ions from clarified juice using a continuous multi-column ion exchange resin column includes the following steps:

[0019] Production process: Sugarcane juice is decalcified by passing through the resin layer of multiple parallel ion exchange resin columns to obtain a decalcified juice solution.

[0020] Backwashing process: Sugarcane juice is used to wash out impurities in the ion exchange resin column that have failed in the production process; here, sugarcane juice refers to undecalcified sugarcane juice.

[0021] Sugar removal process: Use condensed water at a temperature of 70-98℃ to wash out the residual sugarcane juice in the ion exchange resin column after backwashing.

[0022] Regeneration process: The multiple ion exchange resin columns connected in series after the sugar-topping process are regenerated using a regenerating agent;

[0023] Rinsing process: The multiple ion exchange resin columns connected in series after the regeneration process are cleaned with condensed water at a temperature of 30-65℃.

[0024] The effluent solution from the rinsing process is added to the regenerant pipeline and mixed with the regenerant before entering the ion exchange resin column in the regeneration process.

[0025] The amount of regenerant used in each cycle of the regeneration process is controlled at 1.0-2.0 BV.

[0026] The amount of low-temperature condensate used in each cycle of the rinsing process is controlled at 0.5-1.0 BV.

[0027] The volume of a single ion exchange resin column is 1-15 m³. 3 .

[0028] The resin in the ion exchange resin column is a Na-type cation exchange resin.

[0029] The feeding method for the production process is top feeding and bottom discharging; the feeding method for the backwashing process is bottom feeding and top discharging; the feeding method for the water-to-sugar process is top water feeding and bottom discharging; the feeding method for the regeneration process is top regeneration agent feeding and bottom liquid discharging; and the feeding method for the rinsing process is top water feeding and bottom liquid discharging.

[0030] The regeneration process uses 2-5 ion exchange resin columns connected in series. The regenerant enters through the inlet of the first ion exchange resin column and is connected to the inlet of the second ion exchange column through its outlet. The outlet of the second ion exchange resin column is connected to the inlet of the third ion exchange resin column, and so on, with the regenerant exiting through the outlet of the last ion exchange resin column. This reduces the number of ion exchange resin columns and the amount of regenerant used.

[0031] The rinsing process uses 2-5 ion exchange resin columns connected in series. Water enters through the inlet of the first ion exchange resin column and exits through the outlet to the inlet of the second ion exchange resin column. The outlet of the second ion exchange resin column then exits through the inlet of the third ion exchange resin column, and so on, exiting through the outlet of the last ion exchange resin column. This saves on the amount of rinsing water used.

[0032] The above-described solution of the present invention has at least the following beneficial effects:

[0033] The regenerator for decalcified resin is sodium chloride solution obtained by the sodium carbonate chemical method of regenerating liquid, which is repeatedly recycled. This solves the problem of environmental treatment of regenerating liquid and can make full use of the residual sodium chloride in the regenerating liquid, thereby reducing the amount of regenerator required.

[0034] The sodium carbonate chemical treatment process enables the recycling of the regenerated liquid, reducing wastewater discharge during large-scale production and lowering industrial production costs. Solid sodium chloride is dissolved using a dilute sodium chloride solution obtained from the reaction filtration of the regenerated liquid, avoiding the need for external water usage, reducing the total amount of regenerated liquid, and thus achieving recycling.

[0035] Multiple studies have shown that regenerators treated with specific processes (including over-reaction and pH adjustment) do not affect the regeneration performance of the resin. The resin's adsorption capacity recovers well after regeneration, and its throughput remains stable, demonstrating the long-term feasibility of this recycling process and overcoming the technical prejudice that regenerated solution reuse may lead to performance degradation.

[0036] The sugarcane juice decalcification method of the present invention has a good decalcification effect. After decalcification, the calcium ion content is reduced from 400-600 ppm before decalcification to below 0-60 ppm after decalcification. The processing capacity is 45-50 BV, and the decalcification rate is as high as 90% or more.

[0037] The sugarcane juice decalcification method of the present invention obtains a decalcified juice solution, i.e. a softened juice solution, which enters subsequent processes such as evaporators. This greatly reduces scaling in equipment such as evaporators and crystallizers, eliminating the need to shut down the evaporators and crystallizers for descaling every day, saving manual descaling costs, and achieving energy-saving, green, and low-carbon production. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the decalcification resin regeneration liquid treatment process of the present invention.

[0039] Figure 2 This is a schematic diagram of the sugarcane juice decalcification method of the present invention.

[0040] Figure 3 This is a flowchart of the method for decalcifying the juice and the process for treating the regenerated liquid of the present invention. Detailed Implementation

[0041] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0042] A method for treating sugarcane juice decalcification resin regeneration liquid, wherein the clear liquid obtained by treating the sugarcane juice decalcification resin regeneration liquid with sodium carbonate is prepared as a regenerator for sugarcane juice decalcification resin.

[0043] Specific processing methods are as follows: Figure 1 As shown, it includes the following steps:

[0044] S1. The sugarcane juice decalcification resin regeneration liquid is stored in the regeneration liquid tank and then enters the chemical reaction process. Sodium carbonate in the sodium carbonate storage tank is added to the chemical reaction process through a spiral conveyor. After the sugarcane juice decalcification resin regeneration liquid reacts fully with excess sodium carbonate, a mixture of sodium chloride and calcium carbonate is obtained.

[0045] S2. The mixture of sodium chloride and calcium carbonate is filtered to obtain calcium carbonate precipitate and clear sodium chloride filtrate. Part of the sodium chloride filtrate is sent to the salt dissolving tank, where solid sodium chloride is added to prepare a saturated sodium chloride solution. The other part of the sodium chloride filtrate is sent to the filtrate storage tank, and subsequently used together with the saturated chloride solution to prepare a regenerant for resin regeneration. This regenerant is 8%-10% sodium chloride with a pH of 6.5-9.5.

[0046] A method for decalcifying sugarcane juice uses a continuous multi-column ion exchange resin column to remove calcium ions from sugarcane juice. The clear liquid obtained by treating the sugarcane juice decalcification resin regenerated solution with sodium carbonate is used as a regenerator for the sugarcane juice decalcification resin.

[0047] The specific methods for decalcifying sugarcane juice are as follows: Figure 2 As shown, the process includes the following steps:

[0048] Production process: The clarified juice in the feed tank is filtered again before entering the production area, which consists of multiple parallel ion exchange resin columns. After passing through the resin layers for ion exchange, the clarified juice is decalcified to obtain a decalcified clarified juice solution. The volume of a single ion exchange resin column is 1-15 m³. 3 The resin in the ion exchange resin column is a Na-type cation exchange resin. The feeding method in the production process is top feeding and bottom discharging.

[0049] Backwashing Process: After the ion exchange resin column becomes saturated and fails during the production process, it is switched to the backwashing zone. The backwashing zone consists of one ion exchange resin column, and impurities inside the failed ion exchange resin column are washed out using feed clarified juice—undecalcified clarified juice. The feeding method for the backwashing process is bottom feed and top discharge. The backwash liquid discharged from the backwashing process enters the feed tank. The applicant found that undecalcified sugarcane clarified juice has fewer impurities than the failed ion exchange resin column. Backwashing can wash out the fine impurities accumulated on the upper part of the resin layer inside the column, and at the same time loosen the resin. Since the backwashed material cannot enter the decalcification process, using water or decalcified clarified juice would result in a large waste of resources. Therefore, using undecalcified sugarcane clarified juice to backwash the failed resin column in production can achieve the backwashing effect and reduce production costs.

[0050] Water-top sugar process: After backwashing, the ion exchange resin columns are switched to the water-top sugar zone, which consists of 2-5 ion exchange resin columns connected in series. High-temperature condensed water (70-98℃) is used to wash away any residual clarified liquid from the backwashed ion exchange resin columns. The feeding method for the water-top sugar process is top-in, bottom-out.

[0051] Steam condensate is the condensate from the steam produced during the sugar mill's production process. Depending on the number of effects, there will be steam condensate at different temperatures. This water has a very low conductivity and a slightly alkaline pH value, making it suitable as a substitute for demineralized water. Using high-temperature steam condensate, the sugar water is pushed out and kept at a high temperature before flowing back to the feed tank, thus reducing steam consumption during production.

[0052] Regeneration process: After the ion exchange resin columns have completed the water-top sugar process, they are switched to the regeneration zone. The regeneration zone consists of 2-5 ion exchange resin columns connected in series. A regenerant is used to regenerate these multiple ion exchange resin columns after the water-top sugar process. The regenerant is prepared by first... Figure 1 The process shown yields a sodium chloride solution, which is then mixed with hydrochloric acid to adjust the pH to 6.5-9.5, ultimately producing the regenerant.

[0053] In the regeneration process, the regenerant is fed into the inlet of the first ion exchange resin column and its outlet is connected to the inlet of the second ion exchange column. The outlet of the second ion exchange resin column is connected to the inlet of the third ion exchange resin column, and so on. The regenerant discharged from the outlet of the last ion exchange resin column is the regenerated liquid, which is used for the aforementioned treatment.

[0054] Washing Process: After regeneration, the ion exchange resin columns are switched to the washing zone, which consists of 2-5 ion exchange resin columns connected in series. Low-temperature condensed water at 30-65℃ is used to wash these columns. Water enters through the inlet of the first ion exchange resin column and is connected to the inlet of the second column via its outlet. The outlet of the second column is connected to the inlet of the third column, and so on, exiting through the outlet of the last column. The discharged solution is added to the regenerant pipeline and mixed with the regenerant before entering the ion exchange resin columns in the regeneration process.

[0055] The ion exchange resin column, after rinsing, is switched back to the production area. Example 1

[0056] The following is a description of the decalcification method for juice and the regenerated liquor treatment process, illustrated by a flowchart. Figure 3 As shown:

[0057] The decalcification process for the clarified juice involves multiple Na-type cation exchange resin columns, each with a volume of 1-15 m³. 3 The multiple ion exchange resin columns are divided into a production zone 101, a backwash zone 102, a water-to-sugar zone 103, a regeneration zone 104, and a rinsing zone 105, which respectively perform the production process, backwash process, water-to-sugar zone, regeneration process, and rinsing process.

[0058] Production Area 101: Includes multiple (≥2) parallel-connected ion exchange resin columns. The clarified juice raw material undergoes ion exchange through the resin layers of these columns, resulting in decalcification and the acquisition of a decalcified clarified juice solution (softened clarified juice). The upper inlet of each ion exchange resin column is connected to the clarified juice feed pipe 6, the automatic filter 5, and clarified juice pumps 2 and 3 (one pump is on standby). Clarified juice pumps 2 and 3 are connected to the automatic filter 5 via clarified juice pipe 4. The clarified juice pumps transport the material from the feed tank 1 to the ion exchange resin columns. The lower inlet of each column is connected to the clarified juice discharge pipe 7 and the softened clarified juice tank 8. A clarified juice bypass pipe 11 is installed between the softened clarified juice tank 8 and the clarified juice pipe from the sedimentation tank to facilitate material switching when the clarified juice decalcification process is stopped. The material in the softened clarified juice tank 8 is transported to the evaporation section by the softened clarified juice pump 9 through pipe 10. In this embodiment, the production area 101 is equipped with 6 ion exchange resin columns (N5-N10 ion exchange resin columns), but the number of 6 is not fixed. In actual industrial production, the number of ion exchange resin columns can be increased or decreased according to the production volume.

[0059] Backwashing Zone 102: Includes a spent ion exchange resin column switched from the production zone. In this embodiment, backwashing zone 102 is equipped with one ion exchange resin column (N4 ion exchange resin column). The lower end of this ion exchange resin column is connected to the clarified juice pipe after the automatic filter 5 and the backwash feed pump 21 and backwash feed pipe 22. The lower end of the ion exchange resin backwash feed pipe 22 is also connected to the compressed air backflushing pipe 12. Valves are installed on the pipes. If necessary, compressed air can be used to loosen the resin in the ion exchange resin column first, reducing backwash material consumption and improving backwashing efficiency. The upper end of the ion exchange resin column is connected to the backwash discharge pipe 23. The backwash discharge returns to the front end of the main process for re-filtration. Automatic on / off valves are installed on the corresponding pipes to perform the blowing and backwashing operations in sequence.

[0060] The backwashing process uses the pre-decalcification clarified juice to wash out impurities from the ion exchange column. The backwash solution is returned to the main process for re-filtration and decalcification treatment. Traditional processes use pure water for backwashing, but here the pre-decalcification clarified juice is used. The amount of backwash solution does not affect the material's saturation; the amount mainly depends on the cleanliness of the incoming clarified juice. The backwash solution is returned to the front end of the main process for filtration and then continues to be used in the production system. This method can reduce the amount of water used outside the process and avoid increasing energy consumption.

[0061] Water-top sugar zone 103: includes 2-5 ion exchange resin columns switched from the backwash zone. In this embodiment, the water-top sugar zone 103 is equipped with 3 ion exchange resin columns connected in series to top the sugar (N1-N3 ion exchange resin columns). However, the number of 3 columns is not fixed. In actual industrial production, the number of ion exchange resin columns can be increased or decreased according to the production volume.

[0062] The water-topped sugar process uses 70-98℃ high-temperature condensed water to wash the clarified juice in the ion exchange column to 0 saturation. The upper end of the first ion exchange resin column is connected to the high-temperature condensed water pipe 31. Water enters from the upper end of the ion exchange resin column and material exits from the lower end in the water-topped sugar process. This water-inlet washing method can clean the material more quickly. Moreover, by using multiple columns in series to top the sugar, the water consumption is 0.5-1.0 BV, which can wash the sugar to 0 saturation. The water consumption is greatly reduced compared to the traditional single-column water consumption of 1-1.5 BV. The lower end of the last ion exchange resin column is connected to the feed tank 1 through the sugar water recovery pipe 32.

[0063] Regeneration Zone 104: This zone includes 2-5 ion exchange resin columns switched from the water-sugar zone. The resin in the ion exchange resin columns is regenerated using sodium chloride solution obtained after the regeneration solution has undergone a sodium carbonate chemical process. In this embodiment, Regeneration Zone 104 is equipped with 3 ion exchange columns connected in series (N14-N16 ion exchange resin columns). The upper end of the first ion exchange resin column is connected to the regenerant feed pipe 41. The lower end of the first ion exchange resin column is connected in series to the upper end of the second ion exchange resin column via a pipe. The lower end of the second ion exchange resin column is connected in series to the upper end of the third ion exchange resin column via a pipe. The lower end of the third ion exchange resin column is the discharge point. The lower end of the third ion exchange resin column is connected to the regeneration solution tank 46 via pipe 45. At this time, the material in the regeneration solution tank 46 is a solution rich in calcium chloride. This solution is transported to the regeneration solution reaction process via the regeneration solution to reaction tank pipe 47. The amount of regenerant used in the ion exchange columns is 1.0-2.0 BV. However, the number of 3 columns is not fixed; in actual industrial production, the number of ion exchange resin columns can be increased or decreased depending on the production volume.

[0064] When the last ion exchange column in the regeneration zone is switched from the water-top sugar zone, it contains a small amount of water. When the regenerant enters the column, the initial wash solution discharged has a sugar content of 0 and a very low chloride ion content. Depending on the amount of regenerant to be recycled, about 0.2-0.8 BV of the initial wash solution is connected to the recovery water tank 43 through the regenerant discharge pipe 42 from the bottom of the last ion exchange column. At this time, the chloride ion content of the wash solution in the recovery water tank 43 is controlled at 0-1000 mg / L, the calcium salt content is 0-100 ppm, and the COD content is 0-4000 mg / L. The amount of water recovered is about 0.2-0.8 BV, which can be transported to the external cooling tower for recycling through the recovery water pump 44.

[0065] Rinsing zone 105: Includes 2-5 ion exchange resin columns switched from the regeneration zone. The ion exchange columns are rinsed with 30-65℃ low-temperature condensate water. When the rinsing water volume is 0.5-1.0 BV, a rinsing solution with 0% saturation, 0% calcium salt content, and conductivity <1000 μS / cm can be obtained. In this embodiment, rinsing zone 105 is equipped with 3 ion exchange resin columns connected in series (N11-N13 ion exchange resin columns). The upper end of the first ion exchange resin column is connected to the low-temperature condensate water pipe 82 and the low-temperature condensate water pump 81, and its lower end is connected in series through a pipe to the upper end of the second ion exchange resin column. The lower end of the second ion exchange resin column is connected in series through a pipe to the upper end of the third ion exchange resin column, and the lower end of the third ion exchange resin column is the discharge outlet. The lower end of the third ion exchange resin column is connected in series via a pipe to the regenerant feed pipe 41, which is connected to the upper end of the first ion exchange resin column in the regeneration zone 104. Since the third column in the rinsing zone is switched from the regeneration zone, there is still some unused regenerant inside. Therefore, the outlet pipe of the rinsing zone is connected to the inlet pipe of the regeneration zone, and the rinsing solution is used in the regeneration zone. Thus, the rinsing zones are connected in series to save rinsing water, and the rinsing zone and regeneration zone are connected in series for regeneration, allowing for full utilization of the rinsing solution and saving regenerant usage. A mixer is installed on the regenerant feed pipe 41. The number of resin columns in the rinsing zone (3) is not fixed; in actual industrial production, the number of ion exchange resin columns can be increased or decreased according to the production volume.

[0066] The process of clearing juice and decalcifying is continuous. When the ion exchange resin column in the production area becomes saturated, it is switched out and enters the backwashing area. After being cleaned, it is switched to the water-sugar-topping area, regeneration area, and rinsing area. Through sequential switching, the number of ion exchange resin columns in each working area is kept constant, so that clearing juice and decalcifying can be carried out continuously.

[0067] The chemical treatment process for regenerated liquid using sodium carbonate includes a chemical reaction zone 106, a filtration zone 107, and a regenerator preparation zone 108, which respectively perform the sodium carbonate chemical reaction process, the filtration process, and the regenerator preparation process, wherein:

[0068] Chemical reaction zone 106: This includes a pipeline 47 connecting the regenerated liquid from regenerated liquid tank 46 to reaction tanks 54 and 55, both equipped with stirrers. One tank is used as a backup. The regenerated liquid is fed from the top and discharged from the bottom. Sodium carbonate is conveyed to sodium carbonate storage tank 52 via elevator 51. Sodium carbonate is discharged from the bottom of sodium carbonate storage tank 52, and the discharge pipeline is connected to a spiral conveyor trough 53. The outlet pipeline of the spiral conveyor trough 53 is connected to the top of both reaction tanks 54 and 55. Sodium carbonate storage tank 52 is equipped with a weighing sensor, which can accurately control the amount of sodium carbonate added. Sodium carbonate is added from the spiral conveyor trough 53 to either reaction tank 54 or reaction tank 55. The purpose of the stirrers in the reaction tanks is to ensure that the sodium carbonate reacts quickly and fully with the calcium ions in the regenerated liquid. The reaction time is generally controlled between 10-40 minutes, resulting in a turbid substance with calcium carbonate precipitate. The lower inlet of reaction tank 54 (first reaction tank) or reaction tank 55 (second reaction tank) is connected to mud pump 56 (first reaction tank) or mud pump 57 (second reaction tank) and reaction liquid conveying pipeline 58, respectively, to transport the material to the filtration process. One mud pump is in operation and one is on standby. The amount of sodium carbonate added is N times the amount of calcium ions in the regenerated liquid, where N = 1.5-3.5. The reaction temperature is controlled at 30-60℃, and the stirring reaction time is 10-40 minutes. The calcium ion reaction rate can reach over 95%.

[0069] In this embodiment, the sodium carbonate elevator is not essential equipment and can be configured according to the production site. The upper openings of reaction tank 1 (54) and reaction tank 2 (55) equipped with agitators are respectively provided with circulation pipes connected to the outlet of the mud pump to prevent blockage of the inlet pipes when the reaction tanks are not in use. The upper opening of reaction tank 2 (55) is provided with a reaction liquid circulation pipe 59 connected to the outlet of the plate and frame filter press to receive the reaction liquid for return use in case of filtration abnormalities.

[0070] Filtration zone 107 includes the reaction liquid conveying pipeline 58 and plate and frame filter presses 61 and 62. One plate and frame filter press is in operation while the other is on standby. The outlet filtrate pipeline 63 of the plate and frame filter press is connected to the upper opening of the filtrate tank 64. The lower opening of the filtrate tank is connected to the filtrate pump 65 and to the filtrate filters 66 and 67, respectively, and to the filtrate desalination tank pipeline 68. The two filters are used in parallel. The feed inlets of both plate and frame filter presses 61 and 62 are connected to compressed air pipelines and low-temperature condensate pipelines 82. The outlets of both plate and frame filter presses are equipped with drain pipes for emergency drainage in case of production abnormalities.

[0071] The regenerant preparation area 108 includes a filtrate to regeneration pipeline 69 and a salt dissolving tank 71. Solid sodium chloride is dissolved in the salt dissolving tank 71 using the filtrate from the filtrate to salt dissolving tank pipeline 68 as a solvent. The resulting saturated solution is connected to a brine pump 72 and a brine pipeline 73 via the lower outlet pipeline of the salt dissolving tank. The saturated brine is then connected to the filtrate to regeneration pipeline 69 via the brine pipeline 73. After being adjusted by an online metering instrument to prepare an 8%-10% sodium chloride regenerant, it is finally connected to the regenerant inlet pipeline 41. The regenerant pH control system is connected to the hydrochloric acid pump 75, a hydrochloric acid pipeline 76, and the regenerant inlet pipeline 41 via the lower outlet of the hydrochloric acid storage tank 74. The hydrochloric acid and regenerant are mixed via a pipeline mixer 77, and the resin in the regeneration area is regenerated after being controlled by an online pH meter. The pH value of the regenerant solution is 6.5-9.5. The salt dissolving tank is equipped with a compressed air pipeline for pneumatic stirring of the brine.

[0072] The chemical reaction treatment of the regenerated liquid is carried out in continuous production. The regenerated liquid is circulated sequentially from the chemical reaction zone, the filtration zone, and the regenerator preparation zone to ensure the normal operation of the juice clearing and decalcification process. Example 2

[0073] Chemical treatment process test of regenerated liquid sodium carbonate

[0074] Sodium chloride is the most traditional regenerator for Na-type cation exchange resins. It works by providing sodium ions (Na+). + To replace calcium (Ca) in the resin 2+ ) and magnesium (Mg 2+ The sodium carbonate ion is reacted with calcium ions in the solution to restore the exchange capacity of the resin; the sodium carbonate chemical method for removing calcium salts from the solution is a classic chemical precipitation method, in which sodium carbonate reacts with calcium ions in the solution to form calcium carbonate precipitate, which is then removed.

[0075] (1) Using the decalcification process of Example 1, the regenerant initially used on the exhausted resin was a 10% sodium chloride solution. The regenerant obtained from resin regeneration contained a large amount of calcium chloride and some unused sodium chloride. After adding excess sodium carbonate to react with it, the reaction temperature was controlled at 30~40℃. After filtration, a sodium chloride solution with low calcium ion content was obtained as the regenerant. The comparative data are as follows:

[0076]

[0077] N refers to the multiple of the amount of sodium carbonate added to the amount of calcium ions in the regenerated solution. N = 1.2 means that the amount of sodium carbonate added is 1.2 times the amount of calcium ions in the regenerated solution.

[0078] The results show that the more sodium carbonate is added to the regenerated solution, the lower the calcium ion content in the filtrate after the reaction. When N=1.5-4.0, the calcium ion reaction rate in the regenerated solution can reach over 95%. Regardless of the calcium ion content in the regenerated solution, after adding an appropriate amount of sodium carbonate, the calcium ion concentration in the filtrate can be ≤200mg / L, and the calcium ion reaction rate can reach over 95%. Considering cost savings, N=1.5-3.5 can be selected.

[0079] (2) Using the decalcification process of the juice in Example 1, the regenerated liquid obtained by regenerating the calcium-saturated resin column was obtained. When N=3.5, the reaction temperature was controlled at 30~40℃. The calcium ion content of the filtrate was obtained at different reaction times as follows:

[0080]

[0081] The results show that the reaction time between sodium carbonate and calcium ions is within 10-40 minutes. Regardless of the concentration of calcium ions in the regenerated solution, the reaction rate can reach over 99% when sufficient sodium carbonate is added.

[0082] (3) Using the decalcification process of Example 1, the regenerated liquid obtained by regenerating the calcium-saturated resin column, when N=3.5 and the stirring reaction time is within 10-40 minutes, under different temperature conditions, the calcium ion content index of the filtrate is as follows:

[0083]

[0084] The results show that at N=3.5, the higher the temperature, the higher the calcium ion concentration in the filtrate after the reaction. When the temperature is controlled between 30℃ and 60℃, the calcium ion reaction rate can reach over 99%. In large-scale production, the appropriate value can be determined based on the material temperature.

[0085] The above experiments show that: N=1.5-3.5, reaction time 10-40 minutes, reaction temperature controlled at 30℃-60℃, calcium ion reaction rate of regenerated liquid reaches more than 95%, and calcium ion content of the obtained filtrate can be controlled below 200mg / L.

[0086] Considering the excess CO3 remaining when treating the regenerated liquid using the sodium carbonate method 2- Residue in the regenerator will react with Ca on the resin. 2+ CaCO3 precipitate forms and remains in the resin column, unable to be discharged, affecting subsequent production. Based on the CO3 in the sodium chloride regenerator... 2- The residual amount was eliminated by adding HCl, and the pH control parameters of the regenerated solution were as follows:

[0087]

[0088] The results show that residual carbonate ions in the sodium chloride regenerator solution prepared by the sodium carbonate method can be removed by adding acid. When the pH of the regenerator is controlled below 9.5, the carbonate removal rate can reach over 90%, and when the pH is controlled below 8.0, the residual carbonate ions in the sodium chloride regenerator solution are essentially reduced to 0 mg / L. The presence of trace amounts of carbonate ions in the regenerator has little impact on subsequent resin regeneration and recycling. Therefore, the pH of the regenerator solution can be selected between 6.5 and 9.5. Example 3

[0089] The application of the regenerated solution in the recycling and regeneration of resin after treatment with sodium carbonate.

[0090] The regenerated liquid obtained in Example 2 was treated with sodium carbonate (N=3.5), with a reaction time of 10-40 minutes and a reaction temperature of 30-60°C. The resulting sodium chloride solution, after filtration, was then prepared into a sodium chloride solution with a viscosity of approximately 10% using saturated sodium chloride solution as a regenerating agent. The pH of the regenerated liquid was controlled at 6.5-9.5. This process was used to regenerate and recycle the exhausted resin. After 20 cycles, the average decalcification rate of the resin reached over 90%, and the average material throughput in the production area reached 47.5 BV. The statistical data are as follows:

[0091]

[0092] The calcium ion concentration in the feed slurry is 440-560 mg / L, the temperature is 80-90℃, the feed flow rate is 10 BV / h, and the regeneration flow rate is 1 BV / h. Example 4

[0093] The difference between this embodiment and embodiment 3 is that a comparative experiment was conducted on calcium-saturated resin columns using a mixture of salt-alkali solution and sodium hydroxide decalcification solution as regenerators.

[0094] (1) The decalcification process of the clarifier in Example 1 was adopted. All regenerators of the exhausted resin were regenerated using a saline-alkali solution. The saline-alkali solution was prepared by mixing 1% sodium hydroxide and 9% sodium chloride to form a 10% saline-alkali solution, which was used as the regenerator to regenerate the calcium-saturated resin column. The pH value of the regenerator was 9-11, and the regenerated solution was not reused. The feed flow rate was 10 BV / h, and the regeneration flow rate was 1 BV / h. The material throughput in the production area and the decalcification rate after resin regeneration are as follows:

[0095]

[0096] The results showed that when using salt-alkali solution for regeneration, the resin decalcification rate decreased significantly in the fourth cycle of production, and the material throughput decreased from 53 BV to 5 BV. This indicates that the resin recovery ability is very poor when using salt-alkali solution for regeneration, and it cannot maintain normal production.

[0097] (2) The decalcification process of the juice in Example 1 was adopted. The regenerator was a mixture of sodium hydroxide and decalcified juice, i.e., 32% NaOH + decalcified juice, prepared into a regenerator with a concentration of 4%-7% to regenerate the resin. The regenerated liquid was returned to the front end of the production process to be mixed with the sugarcane juice and then clarified. The pH value of the regenerator was 14. The feed flow rate was 10 BV / h, and the regeneration flow rate was 1 BV / h. The material processing volume in the production area and the decalcification rate after resin regeneration are as follows:

[0098]

[0099] The results showed that after 3-4 cycles of operation, precipitates appeared in the resin column during the regeneration process, indicating incomplete resin regeneration. This resulted in a decrease in resin throughput from 45 BV to 24 BV after the third cycle, making it impossible to maintain normal regeneration cycle operation, and the output calcium salt content was also too high. This indicates that when using a mixture of sodium hydroxide and decalcified slurry as a regenerant, the resin's recovery ability is poor, making it unable to maintain normal production.

[0100] Comparative experiments in Examples 2, 3, and 4 revealed that when using a saline-alkali solution as a regenerator, the regenerated solution could not be recycled, and the resin's adsorption capacity decreased after regeneration, resulting in poor decalcification. When using a mixture of sodium hydroxide and decalcified juice as a regenerator, precipitates were generated during the regeneration process, leading to incomplete regeneration, decreased resin adsorption capacity, and poor decalcification. This essentially confirms that the saline-alkali solution and NaOH solution regeneration processes are unsuitable for sugarcane juice with high calcium salt content (400-600 mg / L). However, using NaCl solution as a regenerator effectively solves the problem of incomplete resin regeneration under high calcium salt content in sugarcane juice. Furthermore, the regenerator obtained by treating the regenerated solution using the sodium carbonate method can be recycled, effectively addressing the environmental pollution problem of the regenerated solution.

[0101] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for treating sugarcane juice decalcification resin regeneration solution, characterized in that, The clarified liquid obtained by treating sugarcane juice decalcification resin regeneration solution with sodium carbonate chemical method is used as a regenerator for sugarcane juice decalcification resin. The chemical treatment method for sodium carbonate includes the following steps: S1. Sugarcane juice decalcification resin regeneration solution is reacted with excess sodium carbonate to obtain a mixture of sodium chloride and calcium carbonate; S2. The mixture of sodium chloride and calcium carbonate is filtered to obtain calcium carbonate precipitate and clear liquid. Part of the clear liquid is used as a solid sodium chloride solvent to prepare a saturated sodium chloride solution. The remaining clear liquid is mixed with the saturated sodium chloride solution to prepare an 8%-10% sodium chloride regenerator. The pH value of the regenerator solution is adjusted to 6.5-9.

5.

2. The method for treating sugarcane juice decalcification resin regeneration solution according to claim 1, characterized in that, When using the sodium carbonate chemical treatment method, the amount of sodium carbonate added is N times the amount of calcium ions in the regeneration solution, where N = 1.5-3.

5. The reaction time is 10-40 minutes, and the reaction temperature is 30℃-60℃.

3. A method for decalcifying sugarcane juice, characterized in that, A continuous multi-column ion exchange resin column is used to remove calcium ions from sugarcane juice, and the sugarcane juice decalcification resin regeneration solution is treated with the method described in any one of claims 1-2.

4. The method for decalcifying sugarcane juice according to claim 3, characterized in that, The method for removing calcium ions from clarified juice using a continuous multi-column ion exchange resin column includes the following steps: Production process: Sugarcane juice is decalcified by passing through the resin layer of multiple parallel ion exchange resin columns to obtain a decalcified juice solution. Backwashing process: Sugarcane juice is used to wash out impurities in the ion exchange resin column that have failed in the production process; Sugar removal process: Use condensed water at a temperature of 70-98℃ to wash out the residual sugarcane juice in the ion exchange resin column after backwashing. Regeneration process: The multiple ion exchange resin columns connected in series after the sugar-topping process are regenerated using a regenerating agent; Rinsing process: The multiple ion exchange resin columns connected in series after the regeneration process are cleaned with condensed water at a temperature of 30-65℃.

5. The method for decalcifying sugarcane juice according to claim 4, characterized in that, The effluent solution from the rinsing process is added to the regenerant pipeline and mixed with the regenerant before entering the ion exchange resin column in the regeneration process.

6. The method for decalcifying sugarcane juice according to claim 4, characterized in that, The amount of regenerant used in each cycle of the regeneration process is controlled at 1.0-2.0 BV.

7. The method for decalcifying sugarcane juice according to claim 3, characterized in that, The volume of a single ion exchange resin column is 1-15 m³. 3 .

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