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<br />W <br />"-l <br />U1 <br />w::. <br /> <br />no conversion of petroleum-fueled plants to coal. <br />be adopted, additional coal demands of 50 million <br />occur. <br /> <br />Should such a policy <br />tons per year would <br /> <br />2. Saline Water Use for Powerplant Cooling <br /> <br />In reviewing the projected energy development in the Colorado River <br />Basin of coal-fired powerplants, oil shale, and coal conversion com- <br />plexes, the accompanying demand for water quality merits close examina- <br />tion. Some of the anticipated water requirements inherently require <br />high quality (low TDS) water for boiler feed water or process steam. <br />However, about 70 percent of typical plant water needs relate to cooling <br />or reusable processes, and when accompanied by proper treatment, these <br />processes can use water of degraded quality. Because of total contain- <br />ment or zero discharge policies for industrial effluent or blowdown in <br />the Colorado River Basin, recycling and reuse of degraded quality water <br />is already a proven pr act i ce. <br /> <br />It is useful to briefly review the technological processes and options <br />now available to industry that allow the use of saline water, particu- <br />larly for powerp1ant and process cooling. This is not intended to be a <br />comprehensive review of all existing or possible water treatment tech- <br />nologies but rather to identify some workable processes under study. <br /> <br />The processes and opt ions that look promi si ng for sa 1 i ne water coo 1 i ng <br />use include: <br /> <br />a. Wet cooling tower - water treatment options <br />b. Wet cooling tower - brine concentration options <br />c. Saline water cooling tower <br /> <br />a. Water Treatment Options. - Wet cooling towers are extensively <br />employed in the Colorado River Basin to reject heat from the plant <br />cooling fluid to the atmosphere. In this process of evaporative <br />cooling, the circulating water system is normally limited to a few <br />cycles of operation before b10wdown of the concentrated water, As <br />the water is circled through the cooling tower, the coolant concen- <br />trates mineral salts up to high TDS at which point it is considered <br />"blowdown" or wastewater and is removed from the cooling sector. <br />Generally, about 10 to 13 acre~feet per year of water per megawatt <br />of capacity are required. Limited water supplies and higher TDS <br />water have focused attention on the need for improved water treatment <br />and operation at higher cycles of concentration in the cooling <br />system, The Electric Power Research Institute is sponsoring a <br />research program entitled "Treatment of Recircul ated Cool i ng Water" <br />to assist the electric utilities in developing new cooling water <br />treatment methodologies [10]. <br /> <br />Figure 5 summarizes schematically the water treatment options for a <br />wet cooling tower application. In this scheme, incoming makeup water <br />would receive preliminary softening treatment to facilitate removal <br />of scaling or hardness constituents. In order to extend the cycles <br /> <br />IV-16 <br />