Due to increasing concern and recent regulations related to the environmental impact of discharging wastewater from coal fired power plants, both in the USA and in Europe, zero liquid discharge (ZLD) technologies have gained interest. MHPSE has investigated different concepts for elimination of wastewater discharge originating from flue gas desulfurization (FGD) plants. Generally all ZLD technologies aim at the evaporation of the wastewater stream, however they are based on different drying concepts and utilize different energy sources available in a power plant. The considered processes encompass conventional Evaporator / Crystallizer and Wastewater Spray Dryer (WSD), a process developed and patented by Mitsubishi Hitachi Power Systems. In the presented study, integration possibilities of the concepts are evaluated for both new build and existing power plants. Integration options of the selected ZLD technologies into the power plant and process layouts are studied together with the impact on the operation / performance of the power unit. Using models in EBSILON~® Professional and the in-house software DAMAUS as well as further calculations, detailed investigation on a large power plant with regard to the impact on thermal process and efficiency are carried out. Changes in composition and volume of the various products originated from studied processes are discussed with respect to disposal options. The technical complexity as well as the advantages and disadvantages of each process will be discussed together with alternative energy optimization routes.
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