NAV

SQD-815 resin is the latest generation of citric acid specialized resin developed by our company, mainly used in the production of citric acid by the ion exchange method. Compared with other resins used in the citric acid process, the most significant characteristics are mainly manifested in the following aspects:
1. The work exchange capacity has significantly increased;
2. The exchange speed is significantly accelerated, resulting in stronger ability to intercept impurity ions and better discharge quality;
3. Due to the improvement of the resin process formula, the strength of the resin has also been significantly improved;
In order to demonstrate the advantages of SQD-815 resin in production, some basic precautions and parameters during its use are explained as follows;
1. Pre treatment of resin: SQD-815 resin belongs to the category of polymer synthetic organic compounds. To ensure the removal of trace oligomers and impurities brought in during the filling process of the new resin, and not affect the quality of the product (mainly the initial transparency), it is best to perform the following pre treatment operations before the new resin is officially used:
(1) After filling the SQD-815 resin, first perform backwashing (or in a dedicated resin treatment tank) to ensure an 80% backwashing expansion rate to remove impurities and small resin particles until the backwashing water is clear.
(2) Soak the resin in 7-8% salt solution with a dosage of 1-1.5 times the resin volume for more than 12 hours, then rinse with deionized water until the effluent is clear and the conductivity is close to that of the inlet. (Some units may omit this step, it is recommended to use it!)
(3) Inject 2-3% Hcl solution at a flow rate of 4m/h. When the outlet concentration reaches 1.0-1.5%, stop the injection and soak for more than 12 hours. Then rinse with deionized water until the pH of the effluent is about 3-4.
(4) Inject 2-3% NaOH solution at a flow rate of 4m/h. When the outlet concentration reaches 1.0-1.5%, stop the injection and soak for more than 12 hours. Then rinse with deionized water until the pH of the outlet water is around 7.5, and wait for regeneration (if the amount of alkali added in this step increases by 50%, this step is over, and the resin can be directly considered as standby).
2. Regeneration of resin under normal conditions: When SQD-815 resin fails, perform the following operations:
(1) Replacement and squeezing: Use pure water to replace the citric acid solution in the resin at the feed rate to the recycling tank for further exchange. When the concentration of the recovered citric acid solution meets the discharge requirements, the recovery can be stopped;
(2) Backwashing: Use pure water to backwash the SQD-815 resin layer, maintaining a backwashing expansion rate of 80-100% as much as possible until the backwashing water clarifies (preferably with a transmittance greater than 95%);
(3) Regeneration: Feed 2.5-3.5% NaOH solution at a flow rate of 2-3m/h. When the outlet concentration reaches 2% or more, stop feeding alkali (sufficient time can soak for 2 hours);
(4) Replacement: Use deionized water to replace and clean the resin layer at the same flow rate and regeneration direction, with a suitable time of 60-90 minutes;
(5) Cleaning: Continue cleaning SQD-815 resin with deionized water in the direction and flow rate of operation until it is qualified
(6) Operation: Simply put into operation at a flow rate of twice the resin volume;