Cold condensing scrubbing method for fine particle reduction from saturated flue gas

摘要

The wet scrubbing method can be used for reducing particles and recover waste heat from flue gas. But its particle reduction performance is relatively poor, and an outward Stefan flow caused by droplet evaporation may be the main adverse cause. This work aims to improve the performance through developing a cold condensing scrubbing method, wherein an inward Stefan flow is created through water vapor condensing on cold droplets to prompt the particle capture from saturated flue gas. This method has barely been studied, except a few theoretical predictions. These predictions lack experimental verification, which has been performed in this work The particle reduction efficiencies obtained in our experiments are much higher than previous predicted results, thereby increasing the possibility of application. Besides the work to confirm the inward Stefan flow is the dominant mechanism for a condensing droplet capturing fine particles, the contributions of a preceding scrubber and a subsequent demister are also explored to refine the mechanism knowledge system. Variable analysis on scrubbing temperature, liquid-to-gas ratio, and droplet size are addressed to create a valuable characteristic curve figure and to provide guidelines for engineering applications. Furthermore, the technical feasibility and the economic performance of the proposed method are discussed. (C) 2019 Elsevier Ltd. All rights reserved.