A sodium carbonate resource closed-loop recovery system in water produced by an industrial water treatment chemical softening method and a use method thereof

Abstract

The application discloses a kind of industrial water treatment chemical softening method water production sodium carbonate resource closed loop recovery system and use method, it is related to industrial waste water treatment recovery field, including pretreatment unit, adsorption enrichment unit, regeneration conversion unit, concentration reuse unit and control unit;The inlet of the pretreatment unit is used to receive the chemical softening water production containing excess sodium carbonate;Through the depth cooperation of pretreatment unit, adsorption enrichment unit, regeneration conversion unit, concentration reuse unit and control unit, relying on the selective adsorption characteristics of weak base anion exchange resin to carbonate ion and the real-time water quality feedback mechanism of control unit, without artificial periodic sampling assay or estimated reuse amount by experience, can accurately adapt to raw water hardness, temperature fluctuation and ion accumulation state under different working conditions, effectively avoid the risk of excessive dosing or insufficient dosing due to artificial lag.

Description

Technical Field

[0001] This invention relates to industrial wastewater treatment and recycling technology, specifically to a closed-loop recycling system and method for sodium carbonate resources in industrial water treatment chemical softening process products. Background Technology

[0002] With increasingly stringent environmental standards for industrial water treatment, enterprises have placed higher demands on the resource utilization rate and operating costs of water treatment systems. In the process of chemical softening to treat industrial circulating water or boiler feedwater, a large amount of soda ash is usually added to remove calcium and magnesium ions from the water. This process generates high-salt permeable water or regenerated waste liquid containing excess sodium carbonate. Currently, most factories tend to discharge this sodium carbonate-containing wastewater directly or after simple neutralization treatment. This not only wastes valuable sodium carbonate resources but also increases the salt load on subsequent wastewater treatment plants and the sewage discharge costs for enterprises.

[0003] While some existing recycling solutions attempt to reuse sodium carbonate-containing wastewater, they largely rely on manual, periodic sampling and testing to estimate the reuse volume. In traditional manual operation, operators need to manually test water quality indicators and set the flow rate of the return pump based on experience. However, the hardness, temperature, and ion accumulation of raw water vary under different operating conditions, and manual testing has a significant lag, which can easily lead to excessive reuse (causing scaling and blockage in the front-end reaction tank) or insufficient reuse (low resource recovery rate) due to judgment errors. Some recycling devices that claim to be "automatic" only achieve simple level interlocking or timed start-stop, without deep integration with the real-time operating parameters of the front-end chemical softening system (such as influent flow rate and online hardness monitoring data). They cannot directly obtain the real-time sodium carbonate demand gap of the system and the accumulation status of non-target ions (such as chloride ions), and lack integrated functions to automatically adjust the dosage of fresh reagents according to dynamic changes in water quality and automatically maintain the ion balance of the system.

[0004] Traditional solutions rely on manual experience to adjust the return flow rate, which makes it difficult to accurately match the real-time chemical metering requirements of the front-end softening reaction. Furthermore, they are difficult to adapt to seasonal water quality fluctuations and the accumulation of impurities during long-term operation, and are prone to operational accidents such as pipe scaling or excessive effluent due to uncontrolled dosing. Existing simple automated equipment is mostly limited to single-point control, making it difficult to directly obtain water quality parameters specific to the entire process. It lacks the full-process functions of automatically verifying the quality of the concentrate and automatically adjusting the dosing of the reagents in a closed loop, and fails to fundamentally solve the problems of efficient recovery of sodium carbonate resources and stable system operation.

[0005] To address these issues, the applicant proposes a closed-loop recovery system and method for sodium carbonate resources in industrial water treatment chemical softening process products. Summary of the Invention

[0006] The purpose of this invention is to provide a closed-loop recovery system and method for sodium carbonate resources in the product water of industrial water treatment chemical softening process, in order to solve the problems in the prior art where sodium carbonate recovery mostly relies on manual testing, which is slow and prone to scaling or low recovery rate; simple automatic devices only provide single-point control and are not linked with the front-end chemical softening system, making it impossible to sense ion accumulation in real time and dynamically adjust the addition of reagents, and making it difficult to maintain the ion balance of the system.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a closed-loop recovery system for sodium carbonate resources in industrial water treatment chemical softening process products, comprising a pretreatment unit, an adsorption enrichment unit, a regeneration and conversion unit, a concentration and reuse unit, and a control unit.

[0008] The inlet of the pretreatment unit is used to receive chemically softened permeate containing excess sodium carbonate;

[0009] The adsorption enrichment unit is filled with a weak base anion exchange resin. The inlet of the adsorption enrichment unit is connected to the outlet of the pretreatment unit. It is used to selectively adsorb carbonate ions in the water. The outlet of the adsorption enrichment unit is used to discharge low-alkalinity product water or to transport it to the cooling tower for makeup water.

[0010] The regeneration and conversion unit includes a sodium hydroxide storage tank and a delivery pump. The liquid outlet of the regeneration and conversion unit is connected to the adsorption and enrichment unit and is used to deliver sodium hydroxide regeneration liquid to the adsorption and enrichment unit to replace the carbonate ions adsorbed on the resin and convert them into a sodium carbonate-containing regeneration liquid.

[0011] The concentration and reuse unit includes a high-pressure reverse osmosis component and a bypass discharge pipeline. The inlet of the concentration and reuse unit is connected to the outlet of the regeneration and conversion unit. It is used to perform membrane separation and concentration of the regenerated liquid containing sodium carbonate, and the concentrated sodium carbonate water is transported to the front-end chemical softening reaction tank through the return pipeline.

[0012] The control unit is electrically connected to the adsorption enrichment unit, the regeneration conversion unit, and the concentration and reuse unit, respectively, and is used to dynamically adjust the amount of fresh soda ash added at the front end according to the flow rate and concentration of the reflux concentrate.

[0013] Furthermore, the weak base anion exchange resin is a macroporous acrylic or styrene-based weak base anion exchange resin, which has a higher adsorption capacity for carbonate ions than for chloride and sulfate ions in the pH range of 8-10.

[0014] Furthermore, the pretreatment unit includes a multi-media filter and an ultrafiltration filter for thoroughly removing residual suspended solids and fine flocs from the water; the mass fraction of the sodium hydroxide regenerated solution is 2%–8%.

[0015] Furthermore, the high-pressure reverse osmosis component has a rejection rate of more than 96% for sodium carbonate, the permeate outlet of the high-pressure reverse osmosis component is connected to the recycled water network, and the concentrate outlet of the high-pressure reverse osmosis component is connected to the concentrate storage tank; a discharge valve controlled by the control unit is installed on the bypass discharge pipeline.

[0016] A method for using a closed-loop recovery system for sodium carbonate resources in industrial water treatment chemical softening process products includes the following steps:

[0017] S1. The water treated by chemical softening is sent to the pretreatment unit for deep filtration, and then pumped into the adsorption enrichment unit. The weak base anion exchange resin is used to selectively adsorb carbonate ions in the water flow to obtain low-alkalinity water that can be directly discharged in compliance with standards or used as makeup water for cooling towers.

[0018] S2. When the weak base anion exchange resin is saturated with adsorption, stop the water supply and regenerate the weak base anion exchange resin with a sodium hydroxide solution of 2%-8% by mass, and collect the generated high-concentration sodium carbonate regeneration waste liquid.

[0019] S3. The high-concentration sodium carbonate regeneration waste liquid is sent to the high-pressure reverse osmosis unit for concentration. The water produced by the high-pressure reverse osmosis unit is reused, and the concentrated water is collected to obtain a high-concentration sodium carbonate concentrate.

[0020] S4. High-concentration sodium carbonate concentrate is transported to the reaction sedimentation tank of the front-end chemical softening water treatment system, and the dosage of fresh soda ash is dynamically adjusted according to the flow rate and concentration of the return concentrate through an automatic control system to achieve a large-scale replacement.

[0021] Furthermore, in step S1, the pH value or conductivity data of the outlet of the adsorption enrichment unit is monitored in real time, and the rate of change per unit time or the deviation relative to the initial value of the influent is calculated to determine the adsorption saturation state of the weak base anion exchange resin. When the pH value of the effluent continuously decreases and the cumulative decrease reaches the set threshold, or the slope of the conductivity change per unit time exceeds the set limit, the control unit automatically generates a regeneration command, controls the adsorption enrichment unit to stop the influent and drives the regeneration conversion unit to deliver sodium hydroxide regeneration solution to the adsorption enrichment unit.

[0022] Furthermore, in S2, the amount of sodium hydroxide solution used is 1.5-3 times the volume of the weak base anion exchange resin, the regeneration flow rate is controlled at 1-6 BV / h, and the regeneration temperature is controlled at 15-40℃.

[0023] Furthermore, S4 also includes real-time monitoring of the concentration of non-target anions in the circulation system. When the molar ratio of chloride ions to carbonate ions exceeds a preset cumulative threshold, bypass discharge is initiated to maintain the ion balance of the system.

[0024] Furthermore, the permeate from the high-pressure reverse osmosis unit in S3 is transported to the inlet of the pretreatment unit for circulation filtration, or transported to the sodium hydroxide storage tank of the regeneration conversion unit for preparing sodium hydroxide regeneration solution, so as to achieve zero liquid discharge or low water consumption operation of the system.

[0025] Furthermore, the high-concentration sodium carbonate concentrate in S4 is injected into the reaction sedimentation tank of the front-end chemical softening water treatment system through multi-point dosing or a static mixer, and an online pH monitoring feedback loop is set up upstream of the injection point to prevent local supersaturation scaling and ensure sufficient reaction between carbonate ions and calcium and magnesium ions.

[0026] Compared with existing technologies, this invention provides a closed-loop recovery system for sodium carbonate resources in industrial water treatment chemical softening process products. Through the deep synergy of a pretreatment unit, adsorption enrichment unit, regeneration and conversion unit, concentration and reuse unit, and control unit, and relying on the selective adsorption characteristics of weakly basic anion exchange resin for carbonate ions and the real-time water quality feedback mechanism of the control unit, it eliminates the need for regular manual sampling and testing or estimation of reuse amounts based on experience. It can precisely adapt to different operating conditions of raw water hardness, temperature fluctuations, and ion accumulation states, effectively avoiding excessive scaling or other problems caused by manual delays. The system eliminates the risk of waste due to insufficient dosing. It directly utilizes high-pressure reverse osmosis components to achieve efficient concentration of sodium carbonate regenerated solution and reuse of permeate water. Combined with dynamic monitoring of the chloride / carbonate molar ratio and automatic bypass discharge function, it realizes closed-loop control of the entire process from "automatic adsorption saturation determination" to "regenerated solution concentration and reuse" and then to "dynamic reduction of front-end reagents". This significantly reduces the consumption of fresh soda ash and the salt load of wastewater, and completely solves the problems of low resource recovery rate, unstable system operation and easy pipe scaling in traditional solutions, thereby improving the resource utilization rate and economic and environmental benefits of industrial water treatment. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0028] Figure 1 This is a schematic diagram of the system structure provided in an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of the overall process provided for an embodiment of the present invention. Detailed Implementation

[0030] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0031] As attached Figures 1 to 2 As shown:

[0032] Example 1:

[0033] This invention provides a closed-loop recovery system for sodium carbonate resources in industrial water treatment chemical softening process products, comprising a pretreatment unit, an adsorption enrichment unit, a regeneration and conversion unit, a concentration and reuse unit, and a control unit. These five components work synergistically to achieve efficient recovery and closed-loop utilization of sodium carbonate resources.

[0034] The pretreatment unit includes a multi-media filter and an ultrafiltration filter for receiving chemically softened permeate containing excess sodium carbonate and removing residual suspended solids and fine flocs;

[0035] The adsorption enrichment unit is filled with macroporous acrylic weak base anion exchange resin. The inlet is connected to the outlet of the pretreatment unit. It is used to selectively adsorb carbonate ions in the pH range of 8-10. The outlet is used to discharge low-alkalinity product water or transport it to the cooling tower for makeup water.

[0036] The regeneration and conversion unit includes a sodium hydroxide storage tank and a transfer pump. The liquid outlet is connected to the adsorption and enrichment unit to transport sodium hydroxide regeneration solution with a mass fraction of 2%–8%, which replaces the adsorbed carbonate ions with a sodium carbonate-containing regeneration solution.

[0037] The concentration and reuse unit includes a high-pressure reverse osmosis component and a bypass discharge pipeline. The inlet is connected to the outlet of the regeneration and conversion unit. The high-pressure reverse osmosis component has a sodium carbonate rejection rate of more than 96%. The product water outlet is connected to the reuse water pipeline network, and the concentrate outlet is connected to the concentrate storage tank. The bypass discharge pipeline is equipped with a discharge valve controlled by the control unit.

[0038] The control unit is electrically connected to the adsorption enrichment unit, the regeneration conversion unit, and the concentration and reuse unit, respectively. It is used to dynamically adjust the amount of fresh soda ash added at the front end according to the flow rate and concentration of the reflux concentrate, and to monitor the molar ratio of chloride ions to carbonate ions in real time to maintain ion balance.

[0039] The usage method includes the following steps:

[0040] S1. After deep filtration by the pretreatment unit, the chemically softened water is pumped into the adsorption enrichment unit. The control unit monitors the pH value and conductivity change rate at the outlet in real time. When the pH value drops continuously and the cumulative drop reaches the set threshold or the conductivity change slope exceeds the limit, the resin adsorption is automatically determined to be saturated.

[0041] S2. The control unit generates a regeneration command, stops the water intake, and drives the regeneration conversion unit to deliver 1.5-3 times the resin volume of sodium hydroxide regeneration solution at a flow rate of 1-6 BV / h and a temperature of 15-40℃, and collects high-concentration sodium carbonate regeneration waste liquid.

[0042] S3. High-concentration sodium carbonate regeneration waste liquid is sent to the high-pressure reverse osmosis component for concentration. The product water is reused for preparing regeneration liquid or circulating filtration, and the concentrated water enters the concentrated liquid storage tank.

[0043] S4. High-concentration sodium carbonate concentrate is injected into the front-end chemical softening reaction sedimentation tank through a static mixer at multiple points. The control unit dynamically reduces the amount of fresh soda ash added according to the concentration of the concentrate flow rate. When the molar ratio of chloride ions to carbonate ions exceeds the preset threshold, the bypass discharge valve is automatically opened.

[0044] High-hardness raw water winter operation scenario

[0045] Component parameters and adaptation requirements: The pretreatment unit's multi-media filter uses quartz sand / anthracite as its filter media layers, and the ultrafiltration filter membrane has a pore size of 0.03 μm; the adsorption and enrichment unit is filled with macroporous acrylic weak-base anion exchange resin, with an operating temperature range of 5-45℃, and an adsorption capacity for carbonate ions reaching 1.2 mmol / mL at pH 9.0, which is higher than that for chloride and sulfate ions; the regenerated solution mass fraction in the sodium hydroxide storage tank is set to 4%, and the rated flow rate of the transfer pump is 10 m³ / mL. 3 / h; High-pressure reverse osmosis module operating pressure 3.5-5.0MPa, sodium carbonate rejection rate of single membrane element ≥97%, permeate conductivity ≤50μS / cm; Control unit with built-in PLC controller, pH value monitoring accuracy ±0.01, conductivity monitoring accuracy ±1μS / cm, chloride ion online analyzer detection range 0-5000mg / L, bypass discharge valve response time ≤5 seconds; Static mixer mixing efficiency ≥95%, online pH value monitoring feedback loop sampling frequency 1 time / second upstream of injection point.

[0046] Before system startup, weak base anion exchange resin is filled into the adsorption enrichment unit to the designed height, and the pretreatment unit completes the backwashing procedure; a 4% mass fraction regenerated solution is prepared in the sodium hydroxide storage tank and preheated to 25°C; the control unit inputs basic parameters such as raw water hardness 350 mg / L (calculated as CaCO3), excess sodium carbonate 200 mg / L, and initial chloride ion concentration 150 mg / L, and sets the adsorption saturation criterion as a decrease in effluent pH of 0.5 units compared to influent for 10 minutes, or a conductivity rise rate exceeding 10 μS / (cm·min); the cumulative threshold for the chloride to carbonate molar ratio is set to 0.3, and bypass discharge is triggered if this value is exceeded; the target sodium carbonate concentration in the high-pressure reverse osmosis component concentrate is set to 80 g / L, and the target fresh soda ash replacement rate is set to 70%.

[0047] In winter, the raw water temperature is 8℃. The chemically softened product water has a sodium carbonate concentration of 210 mg / L, a pH of 9.2, and a conductivity of 1800 μS / cm. After passing through the pretreatment unit, the suspended solids content is ≤1 mg / L, and the water enters the adsorption enrichment unit. After running for 4 hours, the control unit monitors that the pH of the effluent from the adsorption enrichment unit drops from 9.1 to 8.5, with a cumulative decrease of 0.6, and the conductivity change slope reaches 15 μS / (cm·min). The resin is determined to be saturated, the inlet valve is automatically closed, and the regeneration program is started. The transfer pump pumps 4% sodium hydroxide regeneration solution with a flow rate of 3 BV / h and a temperature of 25℃, which is twice the volume of the resin. The regeneration process lasts for 40 minutes, and a regeneration waste liquid with a sodium carbonate concentration of about 65 g / L is collected.

[0048] The regenerated wastewater is pumped into the high-pressure reverse osmosis unit via a booster pump and operates at a pressure of 4.2 MPa. The sodium carbonate concentration in the permeate is <2 g / L and is recycled to the sodium hydroxide storage tank for preparing the regenerated solution. The sodium carbonate concentration in the concentrate is increased to 85 g / L and then enters the concentrate storage tank. The control unit calculates the concentrate flow rate in real time (5 m³ / s). 3 With a concentration of 85 g / L, the equivalent sodium carbonate recycling rate is 425 kg / h. The system then sends an instruction to the front-end chemical softening system to reduce the fresh soda ash dosage from 600 kg / h to 180 kg / h (replacement rate 70%).

[0049] Meanwhile, the online chloride ion analyzer monitored that the chloride ion concentration in the circulation system accumulated to 1200 mg / L, the carbonate concentration was 8500 mg / L, and the molar ratio was calculated to be 0.28 (not exceeding the threshold of 0.3). The bypass discharge valve remained closed. If the chloride ion accumulation caused the molar ratio to rise to 0.32 after 24 hours of continuous operation, the control unit immediately opened the bypass discharge valve, discharged 5% of the concentrate and added the same volume of fresh water, so that the molar ratio dropped back to below 0.25.

[0050] High-concentration sodium carbonate concentrate is injected into the reaction sedimentation tank through a static mixer using a three-point injection method. The pH monitoring feedback loop upstream of the injection point displays a stable pH value of 10.5±0.2 in real time, with no localized supersaturation scaling. The calcium and magnesium ion removal rate remains above 98%.

[0051] This recycling process requires no manual sampling or testing. The system automatically completes the entire process of "adsorption monitoring → regeneration triggering → membrane concentration → dynamic dosing → ion balance". The consumption of fresh soda ash is reduced by 70%, and wastewater is discharged at zero. It effectively solves the problems of scaling risk and resource waste caused by manual delays, and achieves efficient closed-loop recycling of sodium carbonate resources and stable system operation.

[0052] Example 2:

[0053] High-load operation scenario in summer

[0054] Component parameters and adaptation requirements: The pretreatment unit's multi-media filter uses quartz sand / anthracite as its filter media layers, and the ultrafiltration filter membrane has a pore size of 0.03 μm to adapt to changes in raw water viscosity at high temperatures in summer; the adsorption and enrichment unit is filled with macroporous styrene-based weakly basic anion exchange resin, with an upper limit of heat resistance temperature increased to 50℃, an adsorption capacity of 1.3 mmol / mL for carbonate ions at pH 8.5, and a selectivity coefficient for chloride ions of less than 0.1; the regenerated solution mass fraction in the sodium hydroxide storage tank is set at 6% (the concentration is appropriately increased in summer to overcome high-temperature diffusion resistance), and the rated flow rate of the transfer pump is 12 m³ / min. 3 / h; High-pressure reverse osmosis module operating pressure 4.0-5.5MPa, sodium carbonate rejection rate of single membrane element ≥96.5%, permeate conductivity ≤40μS / cm; Control unit with built-in PLC controller, pH value monitoring accuracy ±0.01, conductivity monitoring accuracy ±0.5μS / cm, chloride ion online analyzer detection range 0-6000mg / L, bypass discharge valve response time ≤3 seconds; Static mixer mixing efficiency ≥98%, online pH value monitoring feedback loop sampling frequency 2 times / second upstream of injection point.

[0055] Before system startup, weak base anion exchange resin is filled into the adsorption enrichment unit to the designed height, and the pretreatment unit completes the high-temperature backwashing procedure; a 6% mass fraction regenerated solution is prepared in the sodium hydroxide storage tank and kept at a constant temperature of 30°C; the control unit inputs basic parameters such as summer raw water hardness of 420 mg / L (calculated as CaCO3), excess sodium carbonate of 240 mg / L, and initial chloride ion concentration of 180 mg / L, and sets the adsorption saturation criterion as a decrease in effluent pH of 0.4 units compared to influent for 8 minutes, or a conductivity rise slope exceeding 12 μS / (cm·min); the cumulative threshold of chloride to carbonate molar ratio is set to 0.25 (more stringent control of salt accumulation is required in summer due to high evaporation), exceeding this value triggers bypass discharge; the target concentration of sodium carbonate in the concentrate of the high-pressure reverse osmosis component is set to 90 g / L, and the target fresh soda ash replacement rate is set to 75%.

[0056] In summer, the raw water temperature is 28℃. The chemically softened permeate has a sodium carbonate concentration of 250 mg / L, a pH of 9.4, and a conductivity of 2100 μS / cm. After passing through the pretreatment unit, the suspended solids content is ≤0.8 mg / L, and the water enters the adsorption enrichment unit. After running for 3.5 hours, the control unit monitors that the pH of the effluent from the adsorption enrichment unit drops from 9.3 to 8.8, with a cumulative decrease of 0.5, and the conductivity change slope reaches 14 μS / (cm·min). The resin is determined to be saturated, the inlet valve is automatically closed, and the regeneration program is started. The transfer pump pumps 2.5 times the resin volume of 6% sodium hydroxide regeneration solution at a flow rate of 4 BV / h and a temperature of 30℃. The regeneration process lasts for 35 minutes, and a regeneration waste liquid with a sodium carbonate concentration of approximately 75 g / L is collected.

[0057] The regenerated wastewater is pumped into the high-pressure reverse osmosis unit via a booster pump and operates at a pressure of 4.8 MPa. The sodium carbonate concentration in the permeate is <1.5 g / L and is recycled to the sodium hydroxide storage tank for preparing the regenerated solution. The sodium carbonate concentration in the concentrate is increased to 92 g / L before entering the concentrate storage tank. The control unit calculates the concentrate flow rate in real time (6 m³ / s). 3 With a concentration of 92 g / L, the equivalent sodium carbonate recycling rate is 552 kg / h. The system then sends an instruction to the front-end chemical softening system to reduce the fresh soda ash dosage from 750 kg / h to 190 kg / h (replacement rate 74.7%).

[0058] Meanwhile, the online chloride ion analyzer detected that the chloride ion concentration in the circulation system had accumulated to 1400 mg / L due to summer water evaporation, and the carbonate concentration was 9200 mg / L. The molar ratio was calculated to be 0.26 (exceeding the threshold of 0.25). The control unit immediately opened the bypass discharge valve, discharged 8% concentrate and added an equal volume of fresh demineralized water, so that the molar ratio quickly dropped back to below 0.22 to prevent excessive salt content from affecting the softening effect.

[0059] High-concentration sodium carbonate concentrate is injected into the reaction sedimentation tank through a static mixer using a four-point injection method. The pH monitoring feedback loop upstream of the injection point displays a stable pH value of 10.8±0.15 in real time, with no localized supersaturation scaling. The calcium and magnesium ion removal rate remains above 98.5%.

[0060] This recycling process requires no manual intervention. The system automatically completes the entire process of "high-temperature adsorption monitoring → high-efficiency regeneration → high-pressure concentration → dynamic addition → strict salt discharge". The consumption of fresh soda ash is reduced by 75%, and wastewater is discharged at zero. It effectively solves the scaling risk and salt accumulation problem caused by human delay under high temperature and high load conditions in summer, and realizes efficient closed-loop recycling of sodium carbonate resources and long-term stable operation of the system.

[0061] Example 3:

[0062] High-load scenarios in summer - automatic regeneration and dynamic dosing after resin saturation

[0063] At an ambient temperature of 28℃, after the system had been running continuously for 3.5 hours, the pH sensor at the outlet of the adsorption enrichment unit detected a drop in the value from 9.3 to 8.8, and the conductivity change slope reached 14 μS / (cm·min), exceeding the preset saturation criterion. The control unit immediately determined that the weak base anion exchange resin was saturated. The control unit then issued a "stop water intake" command and closed the outlet valve of the pretreatment unit. At the same time, the voice and screen prompts "Resin saturated, start regeneration program".

[0064] The control unit automatically retrieves the stored summer regeneration parameters (6% sodium hydroxide concentration, 30℃ temperature, 4BV / h flow rate) and drives the regeneration conversion unit's delivery pump to start, pumping 2.5 times the resin volume of sodium hydroxide regeneration solution into the adsorption enrichment unit. The regeneration process lasts for 35 minutes, and a high-concentration regeneration waste liquid with a sodium carbonate concentration of approximately 75g / L is collected. The regeneration waste liquid is then sent to the high-pressure reverse osmosis module via a booster pump, where it operates automatically at a pressure of 4.8MPa. The permeate is reused, and the sodium carbonate concentration in the concentrate is increased to 92g / L before entering the concentrate storage tank.

[0065] The control unit calculates the concentrate flow rate in real time (6m³). 3 With a concentration of 92 g / L and a corresponding sodium carbonate recycling rate of 552 kg / h, the instruction generation module immediately issued a "reduce fresh soda ash addition" instruction to the front-end chemical softening system, automatically reducing the fresh soda ash addition rate from 750 kg / h to 190 kg / h. Simultaneously, the online chloride ion analyzer detected that the chloride ion concentration in the circulating system had accumulated to 1400 mg / L, and the calculated chloride to carbonate molar ratio was 0.26 (exceeding the summer threshold of 0.25). The control unit immediately opened the bypass discharge valve, discharging 8% concentrate and replenishing with fresh demineralized water, causing the molar ratio to quickly drop back to 0.22.

[0066] High-concentration sodium carbonate concentrate is injected into the reaction sedimentation tank through a static mixer at four points. The pH value is monitored in real time by the pH feedback loop upstream of the injection point and stabilized at 10.8±0.15, with no local scaling. After the concentrate is added and the ion balance is restored, the system automatically enters the next round of adsorption standby state.

[0067] This regeneration and dosing process requires no manual sampling or valve adjustment. It automatically completes the entire process of "saturation determination → regeneration execution → membrane concentration → dynamic reduction of chemicals → salt discharge balance" based solely on preset logic. The consumption of fresh soda ash is precisely reduced by 75%, effectively avoiding the risk of scaling and excessive salt accumulation caused by manual delays under high temperature and high load conditions in summer. The response time is significantly shortened, and the system's operational stability and resource recovery efficiency are further highlighted.

[0068] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A system for closed-loop recovery of sodium carbonate resources from water produced by industrial water treatment chemical softening processes, characterized in that it comprises: It includes a pretreatment unit, an adsorption and enrichment unit, a regeneration and conversion unit, a concentration and reuse unit, and a control unit; The inlet of the pretreatment unit is used to receive chemically softened permeate containing excess sodium carbonate; The adsorption enrichment unit is filled with a weak base anion exchange resin. The inlet of the adsorption enrichment unit is connected to the outlet of the pretreatment unit. It is used to selectively adsorb carbonate ions in the water. The outlet of the adsorption enrichment unit is used to discharge low-alkalinity product water or to transport it to the cooling tower for makeup water. The regeneration and conversion unit includes a sodium hydroxide storage tank and a delivery pump. The liquid outlet of the regeneration and conversion unit is connected to the adsorption and enrichment unit and is used to deliver sodium hydroxide regeneration liquid to the adsorption and enrichment unit to replace the carbonate ions adsorbed on the resin and convert them into a sodium carbonate-containing regeneration liquid. The concentration and reuse unit includes a high-pressure reverse osmosis component and a bypass discharge pipeline. The inlet of the concentration and reuse unit is connected to the outlet of the regeneration and conversion unit. It is used to perform membrane separation and concentration of the regenerated liquid containing sodium carbonate, and the concentrated sodium carbonate water is transported to the front-end chemical softening reaction tank through the return pipeline. The control unit is electrically connected to the adsorption enrichment unit, the regeneration conversion unit, and the concentration and reuse unit, respectively, and is used to dynamically adjust the amount of fresh soda ash added at the front end according to the flow rate and concentration of the reflux concentrate.

2. The system according to claim 1, characterized in that, The weak base anion exchange resin is a macroporous acrylic or styrene-based weak base anion exchange resin, and its adsorption capacity for carbonate ions is higher than that for chloride and sulfate ions in the pH range of 8-10.

3. The system according to claim 1, characterized in that, The pretreatment unit includes a multi-media filter and an ultrafiltration filter to thoroughly remove residual suspended solids and fine flocs from the water; the mass fraction of the sodium hydroxide regenerated solution is 2%–8%.

4. The system according to claim 1, characterized in that, The high-pressure reverse osmosis component has a rejection rate of more than 96% for sodium carbonate. The permeate outlet of the high-pressure reverse osmosis component is connected to the recycled water pipeline network, and the concentrate outlet of the high-pressure reverse osmosis component is connected to the concentrate storage tank. A discharge valve controlled by the control unit is installed on the bypass discharge pipeline.

5. A method for using a closed-loop recovery system for sodium carbonate resources in industrial water treatment chemical softening process products, characterized in that, The system for closed-loop recovery of sodium carbonate resources in the product water of the chemical softening process for industrial water treatment as described in any one of claims 1 to 4 includes the following steps: S1. The water treated by chemical softening is sent to the pretreatment unit for deep filtration, and then pumped into the adsorption enrichment unit. The weak base anion exchange resin is used to selectively adsorb carbonate ions in the water flow to obtain low-alkalinity water that can be directly discharged in compliance with standards or used as makeup water for cooling towers. S2. When the weak base anion exchange resin is saturated with adsorption, stop the water supply and regenerate the weak base anion exchange resin with a sodium hydroxide solution of 2%-8% by mass, and collect the generated high-concentration sodium carbonate regeneration waste liquid. S3. The high-concentration sodium carbonate regeneration waste liquid is sent to the high-pressure reverse osmosis unit for concentration. The water produced by the high-pressure reverse osmosis unit is reused, and the concentrated water is collected to obtain a high-concentration sodium carbonate concentrate. S4. High-concentration sodium carbonate concentrate is transported to the reaction sedimentation tank of the front-end chemical softening water treatment system, and the dosage of fresh soda ash is dynamically adjusted according to the flow rate and concentration of the return concentrate through an automatic control system to achieve a large-scale replacement.

6. The method of using a closed-loop recovery system for sodium carbonate resources in industrial water treatment chemical softening process product water according to claim 5, characterized in that, In step S1, the pH value or conductivity data of the outlet of the adsorption enrichment unit is monitored in real time, and the rate of change per unit time or the deviation relative to the initial value of the influent is calculated to determine the adsorption saturation state of the weak base anion exchange resin. When the pH value of the outlet water is continuously decreasing and the cumulative decrease reaches the set threshold, or the slope of the change in conductivity per unit time exceeds the set limit, the control unit automatically generates a regeneration command, controls the adsorption enrichment unit to stop the influent and drives the regeneration conversion unit to deliver sodium hydroxide regeneration solution to the adsorption enrichment unit.

7. The method of using a closed-loop recovery system for sodium carbonate resources in industrial water treatment chemical softening process product water according to claim 5, characterized in that, The amount of sodium hydroxide solution used in S2 is 1.5-3 times the volume of the weak base anion exchange resin, the regeneration flow rate is controlled at 1-6 BV / h, and the regeneration temperature is controlled at 15-40℃.

8. The method of using a closed-loop recovery system for sodium carbonate resources in industrial water treatment chemical softening process product water according to claim 5, characterized in that, The S4 also includes real-time monitoring of the concentration of non-target anions in the circulation system. When the molar ratio of chloride ions to carbonate ions exceeds a preset cumulative threshold, bypass discharge is initiated to maintain the ion balance of the system.

9. The method of using a closed-loop recovery system for sodium carbonate resources in industrial water treatment chemical softening process product water according to claim 5, characterized in that, The permeate from the high-pressure reverse osmosis unit in S3 is transported to the inlet of the pretreatment unit for circulation filtration, or to the sodium hydroxide storage tank of the regeneration conversion unit for preparing sodium hydroxide regeneration solution, so as to achieve zero liquid discharge or low water consumption operation of the system.

10. The method of using a closed-loop recovery system for sodium carbonate resources in industrial water treatment chemical softening process product water according to claim 5, characterized in that, The high-concentration sodium carbonate concentrate in S4 is injected into the reaction sedimentation tank of the front-end chemical softening water treatment system through multi-point dosing or a static mixer. An online pH monitoring feedback loop is set up upstream of the injection point to prevent local supersaturation scaling and ensure the full reaction of carbonate ions with calcium and magnesium ions.

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