Anti-scaling Effect Of High Frequency Electromagnetic Field On Circulating Cooling Water In Power Plant

The water consumption of circulating cooling water system in industry is numerous. In order to reduce plant water consumption, the common method is to increase the concentration ratio of circulating water. However, it will cause scale deposition and corrosion on the pipe, and then the proceed of production will be interrupted. The traditional anti-scaling method is chemical methods, such as pouring with the acidification and water scale inhibitors. Although chemical methods have significant effect, they inevitably lead to environmental pollution. Along with the national environmental protection policies becoming more and more strict, the physical anti-scaling methods have been paid widely attention and studied. At present there are typical physical methods such as electrostatic method, magnetic method, ultrasonic method, high frequency electromagnetic method. The high frequency electromagnetic method has been rapidly developing and adopting for scale-resistant.This paper analyzes the anti-scaling principle of high frequency electromagnetic field technology by simulating electromagnetic field intensity distribution, developing high frequency pulse generator and parameter measurement system, and then doing anti-scaling experiments. The research works are listed as follows:â‘ The anti-scaling principle of high frequency electromagnetic field technology was discussed in terms of the change of water molecular structure and the formation of calcium carbonate crystals. By using Maxwell software for simulation of electromagnetic field distribution, comparison of two treatment chambers such as coaxial-type and solenoid-type was completed.â‘¡High frequency pulse generator and parameter measurement system circuit were developed. The former device could output bipolar square wave signal whose frequency ranged from 10 kHz to 1 MHz, and peak-peak voltage was up to 400V. On-line parameter measurement includes the value of conductivity, pH, temperature and flow rate.â‘¢The programs for high frequency control, parameter measurement and PC software platform were all compiled and operated very well. High frequency control program realized whether single frequency or sweep frequency mode output. The parameter measurement program was responsible for data processing. The PC software platform realized data display and storage, data table exporting and other functions. â‘£A micro-circulating water equipment and anti-scaling experiments were completed. The calcium carbonate scale is the research object. To study the relationship between anti-scaling effect with the frequency of square wave pulses and the structure of treatment chamber, the values of conductivity, pH, surface tension and solution viscosity were constantly recorded with the same solution concentration, temperature and flow rate. In addition, the crystal morphology of calcium carbonate by scanning electron microscope were observed and compared.The results showed that high frequency electromagnetic field could increase the activity of the water, speed up the nucleation rate of calcium carbonate, and change the structure and size of calcium carbonate crystals. The rule to find ideal frequency point for best anti-scaling effect is not the higher the better. According to data analysis, there are multiple optimal frequencies which scattered in a wide range. Morever, the anti-scaling effect of the coaxial-type treatment chamber is much better than that of the solenoid-type treatment chamber in the same experiment condition.