Experimental study of a zero water consumption wet FGD system

• The existence of a zero water consumption (ZWC) wet FGD system has been confirmed.
• A group of critical operating parameters have been proposed for the ZWC system.
• The ZWC system can be achieved for all coals when slurry temperature <30 °C.

Aiming to the huge water consumption of wet flue gas desulfurization (WFGD), a pilot-scale facility was built and employed to investigate the water consumption with various inlet vapor concentration of flue gas, circulating slurry temperature and inlet flue gas temperature, as well as different desulfurizer, including limestone–gypsum, magnesium, and natrium–alkali. Results show that water consumption decreases with increased vapor concentration in flue gas, while increases with higher temperature of the circulating slurry and the inlet flue gas, and SO2 concentration has a little effect on the water consumption. The water consumption of limestone–gypsum method is the largest, followed by the magnesium method, and the natrium–alkali method has the least water consumption. Meanwhile, critical operating parameters have been found firstly to create a zero water consumption (ZWC) system for all investigated desulfurization methods. For limestone–gypsum, only higher water content lignite can obtain ZWC below 50 °C; While for natrium–alkali, the ZWC system can be built for most of anthracite, bituminous, and lignite coal below 30 °C. Whole research provides considerable guideline for industrial application.