Volume 3: Innovative Solutions for Energy Transitions: Part II

Thermodynamic and Economic Analyses of Desulfurization Wastewater Recovery in Coal-Fired Power Plants Xiaoqu Han, Shuran Zhao, Dan Zhang, Wenchen Yan, Jiping Liu, Junjie Yan

Abstract

Zero emissions of waste gas and water from coal-fired power plants are one of the pathways for cleaner electricity production in China. It is expected to achieve low-cost zero discharge of flue gas desulfurization (FGD) wastewater by applying multi-effect distillation (MED) or multi-stage flash (MSF) technologies and matching different heat sources from the power plant. In the present work, four different integration schemes were proposed for FGD wastewater recovery by concentration and deep desalination. The thermo-economics of different schemes were analyzed in terms of gained output ratio (GOR) and energy cost. The results showed that the cost of auxiliary steam driven MED could be lowered by the integration of thermal vapor compression (TVC). The GOR of MED could be increased by 10%-100% while the energy cost was reduced by approximately 10%-50%. In contrast, the pump electricity consumption should be reduced when MED was driven by flue gas. Moreover, the MSF distillation had stronger adaptability to salt concentration than MED. The energy cost of flue gas driven MSF could be remarkably reduced by lowering the flash temperature difference.

Keywords desulfurization wastewater, zero emissions, MED, MSF, energy cost, thermodynamic analysis