Sensitive and economical wet desulphurization outlet flue gas SOx concentration control method

The invention relates to the technical field of waste gas purification through a semi-liquid phase method, and discloses a sensitive and economical wet desulphurization outlet flue gas SOX concentration control method which is used for controlling the SOX concentration of flue gas at an outlet of an absorption tower when a gypsum method is adopted for desulfurization, and the spraying amount is changed by controlling the frequency of a variable frequency pump through a prediction controller, so that theSOX concentration of flue gas at the outlet of the absorption tower is adjusted; the prediction controller overcomes the hysteresis quality from frequency conversion to the change of the SOX concentration of the flue gas at the outlet of the absorption tower, so that the adjusting process is more sensitive, red line operation of the desulfurization device can be realized, the SOX concentration of the flue gas at the outlet of the absorption tower is prevented from exceeding the standard in the adjusting process