System and method for desulfurizing and decarbonizing flue gas

A system for desulfurizing and decarbonizing a flue gas, comprising:

• a water cooler, having a flue gas inlet for feeding a boiler flue gas after denitrating and dedusting, a condensed water outlet in a bottom of the water cooler, and a wet flue gas outlet, and configured to cool the boiler flue gas to obtain a wet flue gas and condensed water;
• a washing tower, having a wet flue gas inlet communicated with the wet flue gas outlet, a flue gas discharge outlet in a top of the washing tower, a washing liquid inlet in an upper part of the washing tower for receiving a washing liquid, and a solid-liquid mixture outlet in a bottom of the washing tower, and configured to receive the wet flue gas from the water cooler and separate H2O, SO2 and CO2 in a solid form from the wet flue gas to obtain a flue gas discharge and a solid-liquid mixture comprising solid H2O, SO2 and CO2 and the washing liquid;
• a solid-liquid separator, having a solid-liquid mixture inlet communicated with the solid-liquid mixture outlet, and a liquid outlet and a solid outlet, and configured to receive the solid-liquid mixture from the washing tower and separate the solid H2O, SO2 and CO2 from the washing liquid;
• a washing liquid supplementary pipeline provided at a top of the solid-liquid separator;
• and
• a rectification separation column, having a solid inlet communicated with the solid outlet, a gaseous CO2 outlet in a top of the rectification separation column, and an H2O and SO2 outlet in a bottom of the rectification separation column, provided with a reboiler located at the bottom of the rectification separation column, and configured to receive the solid H2O, SO2 and CO2 from the solid-liquid separator and separate CO2 from SO2 and H2O by the reboiler, discharge CO2 from the top of the rectification separation column, and discharge SO2 and H2O from the bottom of the rectification separation column.