Abstract

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.

IPC Classes  ?

• C02F 1/42 - Treatment of water, waste water, or sewage by ion-exchange
• C02F 1/44 - Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
• B01D 35/00 - Filtering devices having features not specifically covered by groups , or for applications not specifically covered by groups Auxiliary devices for filtrationFilter housing constructions

Abstract

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.

IPC Classes  ?

• C02F 1/42 - Treatment of water, waste water, or sewage by ion-exchange
• C07C 19/07 - Acyclic saturated compounds containing halogen atoms containing iodine

Abstract

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.

IPC Classes  ?

• C02F 5/00 - Softening waterPreventing scaleAdding scale preventatives or scale removers to water, e.g. adding sequestering agents
• C02F 1/42 - Treatment of water, waste water, or sewage by ion-exchange
• F24H 9/20 - Arrangement or mounting of control or safety devices
• F22B 37/48 - Devices or arrangements for removing water, minerals or sludge from boilers