Abrégé

The present invention provides a method for purifying or softening water comprising: passing a specific volume of feedwater through at least one service column comprising a strong acid cationic exchange resin capable of binding divalent cations that are present in the feedwater, wherein the loading of the divalent cations on the resin is restricted to about 1 to 25% of the available ion exchange sites on the resin, and the total dissolved solids in the feedwater is greater than 100 mg/l; feeding the water exiting the service column to a reverse osmosis membrane or a nanofiltration membrane to produce permeate water stream and a reject water stream; and passing all or some of the volume of the reject stream corresponding the specific volume of feedwater through at least one off-line column capable of binding monovalent cations; wherein the chemical equivalent ratio of monovalent to divalent cations in the water exiting the service column is greater than 20 to 1; wherein no external source of regenerant salt is used. The inventive method allows for multiple softening/regeneration cycles so that steady state hardness leakage is achieved that is lower than obtainable with conventional ion exchange softening systems.

Classes IPC  ?

• C02F 1/42 - Traitement de l'eau, des eaux résiduaires ou des eaux d'égout par échange d'ions
• C02F 1/44 - Traitement de l'eau, des eaux résiduaires ou des eaux d'égout par dialyse, osmose ou osmose inverse
• B01D 35/00 - Dispositifs filtrants ayant des particularités non couvertes spécifiquement par les groupes , applications non couvertes spécifiquement par les groupes Dispositifs auxiliaires pour la filtrationStructure du carter de filtre

Abrégé

The present invention provides a method of reducing the concentration of an iodide compound using an ion exchange resin. The ion exchange resin is a macroporous resin having sulfur functional groups exchanged with silver, a dry weight capacity of at least 5.0 eq/kg, a mean pore diameter (D50) of about 400 - 800 Ǻ, a pore volume of about 0.4 - 0.6 ml/g, and a surface area of about 20 - 40 m2/g.

Classes IPC  ?

• C02F 1/42 - Traitement de l'eau, des eaux résiduaires ou des eaux d'égout par échange d'ions
• C07C 19/07 - Composés acycliques saturés contenant des atomes d'halogène contenant de l'iode

Abrégé

A new process for ion exchange softening of water used in Once-Through Steam Generators (OTSGs) by recovering and using the salt content of the blowdown water from the OTSG to regenerate the softener resin is provided, thus eliminating the cost for commercial regenerant salt that would otherwise be needed. Further, the very high purity of the salt recovered in the blowdown inherently results in the production of softened water with hardness leakage levels that are an order of magnitude lower than can be attained using commercial salt, thus reducing scale deposit potential and improving operating efficiency and reliability of the OTSG.

Classes IPC  ?

• C02F 5/00 - Adoucissement de l'eauPrévention de l'entartrageAddition à l'eau d'agents antitartre ou détartrants, p. ex. addition d'agents séquestrants
• C02F 1/42 - Traitement de l'eau, des eaux résiduaires ou des eaux d'égout par échange d'ions
• F24H 9/20 - Disposition ou montage des dispositifs de commande ou de sécurité
• F22B 37/48 - Dispositifs ou agencements pour enlever l'eau, les minéraux ou les boues des chaudières