Two-stage bed deionization method and device for seawater desalination

Abstract

The invention discloses a desalinated seawater two-stage bed deionization method and an apparatus thereof. The apparatus is formed through serial connection of a mixed bed filled with strong acidic and weak alkaline resins, and an anion bed filled with a weak alkaline resin. A water desalting process comprises the following steps: desalinated seawater goes through the mixed bed, Na<+> in water is adsorbed by the strong acidic resin, partial Cl<-> is adsorbed by the weak alkaline resin, and residual Cl<-> exits in water as HCl; and discharged water goes through the anion bed, and HCl is absorbed by the weak alkaline resin to prepare product water. A resin regeneration process comprises the following steps: applying a high voltage direct current to the mixed bed, ionizing water to generate H<+> and OH<-> to regenerate the mixed bed resin, forming an alkaline regeneration liquid containing NaOH and NaCl, and allowing the alkaline regeneration liquid to go through the anion bed in order to chemically regenerate the weak alkaline resin; and adjusting the pH value of the obtained regeneration concentrate to 7, and reusing to reverse osmosis devices and other desalting devices. The mixed bed performs its anion bed exchange capability in water desalting in order to guarantee the quality of the discharged water; and the electric regeneration of the mixed bed promotes the chemical regeneration of the anion bed in the resin regeneration, so the regeneration of the anion bed does not consume energy, and the electric regeneration cost of the resin can be reduced.

Description

technical field [0001] The invention relates to a seawater desalination method and device, in particular to a two-stage bed deionization method and device for seawater desalination. technical background [0002] Due to the shortage of freshwater resources, distillation and membrane separation methods are widely used to produce primary freshwater from seawater. The conductivity of water produced by seawater distillation is generally 10-70 μS / cm, and the conductivity of water produced by seawater membrane method can be as low as 10-50 μS / cm (two-stage reverse osmosis); the main salts of the above seawater desalination water are NaCl , the conductivity is tens of μS / cm, and the pH is weakly acidic. In order to obtain high-purity water, this kind of primary product water must be further desalinated. Ion exchange mixed bed or electrodeionization (EDI) requires low influent conductivity, and is often not suitable for directly treating influent with this conductivity level. There...

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Problems solved by technology

This technology can directly treat influent water with a conductivity below 20 μS / cm into high-purity water, but it consumes a lot of energy and is not economical when dealing with influent water with a higher conductivity (such as 50 μS / cm), and is not suitable for the above-mentioned seawater desalination Desalination of water; and in order to take into account the effect of treatment and regeneration, the device uses three kinds of resins: weak acid, strong acid, and strong alkali. When dealing with acidic water such as desalinated water, the exchange capacity of weak acid resin is difficult to effectively exert, which is significant Reduce equipment performance

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