Draught fan speed governing method for dihydrate wet-process phosphoric acid extraction technology

The invention discloses a draught fan speed governing method for a dihydrate wet-process phosphoric acid extraction technology. The method includes the steps that the difference of the inner pressure and the outer pressure of a phosphoric acid extraction tank is detected and converted into an activated gas pressure difference fuzzy set; a pulp temperature difference of a flash evaporation condenser is detected and converted into an activated pulp temperature difference fuzzy set; according to a preset fuzzy rule list, fuzzy reasoning is conducted on the activated gas pressure difference fuzzy set and the activated pulp temperature difference fuzzy set, and the frequency input value of a frequency converter is obtained; and a current signal is generated after the frequency input value of the frequency converter is corrected and the generated current signal is sent into a simulation signal input end of the frequency converter so as to achieve automatic governing of the rotating speed of a draught fan. By means of the draught fan speed governing method, the stability of the process index and the extraction effect of reaction pulp can be improved, the quality stability and production continuity of finished products are improved, and the method plays a positive role in increasing the utilization rate of energy and reducing the environment pollution caused by poisonous gas and has the beneficial effects of being easy to implement, reliable in performance, high in automation degree, good in timeliness, high in antijammping capability and the like.