Desulfurization and waste heat recovery integrated absorption tower and absorption method thereof

The invention provides a desulfurization and waste heat recovery integrated absorption tower and an absorption method thereof, the desulfurization and waste heat recovery integrated absorption tower comprises a desulfurization circulating tower, a waste heat recovery circulating tower and a gas-liquid separator, and the waste heat recovery circulating tower is arranged above the desulfurization circulating tower and is connected with the desulfurization circulating tower through the gas-liquid separator; the gas-liquid separator comprises a partition plate, a gas lifting cap and a supporting beam, the partition plate is used for isolating the waste heat recovery circulating tower and the desulfurization circulating tower, the gas lifting cap is arranged at a vent hole in the partition plate, and the supporting beam is used for supporting the partition plate and the gas lifting cap; the desulfurization circulating tower is used for carrying out desulfurization treatment on boiler flue gas, the desulfurized flu