This paper discusses a commercially viable and novel technology that enables the recovery of the water vapor contained in power plant flue gas streams. Currently, fossil fuel-based power plants consume vast quantities of water for heat rejection, fuel preparation, power augmentation, emissions control, and cycle makeup purposes. At the same time, global water resources are becoming more difficult to procure as water consumption outstrips the pace of renewal. At present, the strategy used to reduce power plant water consumption in areas where water restrictions are stringent is to employ an air-cooled condenser as opposed to once-through cooling or a cooling tower. However, even plants with air-cooled condensers to minimize water consumption require a significant amount of water in several cases in order to allow for required steam drum blowdown, power augmentation systems, and gas turbine inlet evaporative cooling or fogging systems in addition to the aforementioned uses. To offset these observed escalating consumption rates, a new system was devised that can recover a substantial portion of the water vapor present in a flue gas stream. The water recovered by this system is of a quality similar to that of a reverse osmosis system outlet (RO Out). This water can be used for various plant needs as recovered or can receive minimal treatment so that it can be used as direct-cycle makeup. Siemens Power Generation, Inc. (SPG) and the Energy & Environmental Research Center (EERC) at the University of North Dakota have successfully completed the first phase of a U.S. Department of Energy supported pilot-scale program that verified the technical viability of this system. SPG, with the cooperation of the EERC, is currently developing a commercial partnership with the goal of having a 1/10-scale slipstream commercial demonstration by the end of 2007. This paper provides a detailed description of the pilot-scale system and process conditions, presents the reportable results of the recent pilot-scale test program, and discusses the expected commercial characteristics.
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