Study On Scale Inhibition Experiment Of Circulating Cooling Water Under Compound Action By The Electromag-netic Field And Ultrasonic

To explore the effect and mechanism of scale inhibition of circulating cooling water under compound action by the electromagnetic field and ultrasonic, the dual channel industrial circulating cooling water dynamic simulation test bench and the Electromagnetic-ultrasonic field compound scale inhibition processor were designed and made by self, the dynamic scale inhibition experiment were conducted by simulating operation condition of circulating cooling water of power plant.The orthogonal experiment was designed by choosing electrostatic field voltage, ultrasonic frequency, cooling water flow rate, frequency sweep direction of pulse magnetic field for variables. The analysis results indicate that the effect of scale inhibition is good or bad and the difference is bigger under compound action by physical field of different parameters. The scale inhibition rate is 57.42% which it is the best when voltage is 4000 V, ultrasonic frequency is 40 k Hz, ultrasonic power is 300 W, flow rate of circulating cooling water is 1000 L/h, and frequency sweep direction of pulse magnetic field is 10-100 Hz. The flow rate of circulating cooling water, ultrasonic frequency, ultrasonic power and electrostatic field voltage has greater impact on the effect of scale inhibition. The change of pulse magnetic field frequency sweep direction has little impact on effect of scale inhibition.The ion concentration and viscosity of circulating cooling water were monitored by titration method, electrode method and viscosity meter. The results show that the viscosity of circulating cooling water are all increased in different degree under compound action by electromagnetic field and ultrasonic.The CaCO₃ scale were analyzed by X-ray diffraction（XRD） and scanning electron microscope（SEM）. Results indicate that the phase mass fraction, crystallinity, grain size, interplanar spacing and morphology of experimental scale is changed in different degree and direction under the compound action by electromagnetic field and ultrasonic. In some gounps of experiment whose the scale inhibition rate are better, the crystallinity of adherent scale is decreased, the grain size of adherent scale is increased, the interplanar spacing of adherent scale is decreased, the calcite content of non-adherent scale is increased and the coalescence degree of adherent scale is decreased generally. The experiments whose scale inhibition rate are bad show the opposite trend.Compared with the experiment whose scale inhibition rate is the worst, the reasons that scale inhibition effect of experiment whose scale inhibition rate is the best has two. On the one hand, the compound action of electromagnetic-ultrasonic field make the viscosity of circulating cooling water increased and it reduces the degree of partial surpersaturation, it makes grain size of adherent scale increase at the same time and the nucleation of adherent scale is hinder. On the other hand, the interplanar spacing of adherent scale is decreased through the polarization of electrostatic field and cavitation effect of ultrasound, and more calcite generates in the water at the same time, it is easy to deposition in intercept net and reduced the opportunity of recrystallization with adherent scale. The increasing of grain size and the decreasing of interplanar spacing leads that the adherent scale is relatively loose, it is washed away by water easily and the purpose of efficient scale inhibition is achieved.Therefore, the better effect scale inhibition can be achieved under the appropriate compound condition of scale inhibition. But the synergistic effect of compound scale inhibition condition need to be researched more deeply.