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(\.} In <;,j'4 N ~ reservoir, settling of sol Ids In the reservoir and delivery of raw water to ~) the power plant via a pump station located at the reservoir. The quantity of raw water varies for each option depending on the source and process option and the amount of water recovered for recycle. For each process option vapor compression evaporators are used for waste water con- centration and concentrator product water Is used to supply the condensate system. Excess concentrator product Is used to supplement makeup to other plant systems. Admiralty, 90-10 copper nickel, titanium and AI 6x were al I evaluated as potential condenser materials for the process options. Because of the high dissolved solids environment, titanium was selected as the condenser tubing material In al I cases. Titanium Is highly recommended for both sea water and brackish water service. It Is superior to al I other conventional materials In terms of resistance to stress corrosion, pitting, and erosion. In addition, a very high cleanliness factor has been observed. While the heat transfer coef- ficient of titanium metal Is Inferior to that of 90-10 CuNi, the strength of titanium makes possible the use of thinner tube wal Is, largely overcommlng this disadvantage. Within a few weeks or months, the overall heat transfer coefficient becomes essentially equivalent for titanium and 90-10 CuNl, ap- parently due to the superior cleanllnness factor for titanium. Titanium also seems to resist blo-foul Ing to a greater degree than other materials. AL 6X Is an alloy manufactured by Allegheny Ludlum and contains 20% chromium, 24% nickel and 6% molydenum. This high chromium, molybdenum augmented com- position Is typical of the "super stainless" alloys such as "AL29-4C," "Sea- Cure," "Monlt" and "254 SMa". All of these materials have been used in sea water service with appapent success, although no significant operating data or cost comparislons are available. AI I process options evaluated In the study Included titanium tubes in con- densers, 316 stainless steel pump Internals, corrosion resistant valves and sulfate resistant concrete and linings in the circulating water system. Option I-LV - Ix Softenlng/Slde~tream Softenlng/VCE/Evaporatlon Ponds The process flow diagram for Option I Is presented In Figure 4-1 and the process flow and material balances are found In Appendix C. Lower Virgin River water Is transferred from the reservoir to the Ion exchange system that Includes 18 vessels 10 feet In diameter by 15 feet high filled with a total of 11,200 cubic feet of resin. The water Is softened to 40 mg/I calcium and 58 mg/I magnesium. The average flow of 7,900 gpm of softened water Is collected In a 3.5 mill Ion gallon collection basin. The Ion exchange system has been sized at 125% of full load to al low for regeneration require- ments. This results In maximum processing capacity of 13,500 gpm. The softened water Is transferred to the cooling towers on demand. SulfurIc acid, chlorine and scale Inhibitor are added to the circulating water to con- trol pH, scale and biological attack. Scale Inhibitor and chlorine usage are each assumed to average 3 mg/I. The circulating water system Is operated at 4-14 " " ,