Waste‐heat‐assisted zero‐liquid‐discharge route selection for flue gas desulfurization wastewater in a 2 × 1000  MW coal‐fired power plant

Flue gas desulfurization (FGD) wastewater zero‐liquid‐discharge (ZLD) is constrained by wastewater salinity, heat‐source grade, equipment reliability, residual‐solid quality, and plant water balance. This study develops a plant‐level route‐selection framework for waste‐heat‐assisted FGD wastewater ZLD and applies it to a design‐stage 2 × 1000 MW coal‐fired power plant in Zhejiang, China. Two practically feasible routes were evaluated under a unified concentration‐and‐drying boundary: low‐temperature multi‐effect flash concentration plus high‐temperature bypass flue‐gas drying, and air evaporation concentration plus bypass drying. Both routes concentrate 26 t h −1 wastewater to 5.2 t h −1 brine at a concentration ratio of 5, recover approximately 20.8 t h −1 water, and send the residual brine to terminal drying. Multi‐effect flash achieved lower total unit costs than air evaporation under both the steam scenario (15.26 vs. 29.70 USD t −1 ) and the hot‐water scenario (8.09 vs. 9.87 USD t −1 ). The additional investment of multi‐effect flash can be offset within approximately 0.28 years under steam heating and 2.03 years under hot‐water heating. The framework converts plant‐specific engineering constraints into a transferable decision method for large coal‐fired units.