| In industrial production,the evaporation of water during the operation of circulating cooling water leads to a gradual increase in the concentration of scale-forming ions,which can easily cause scaling problems on pipes and heat exchange surfaces.Once the scale is formed on the wall of the equipment,it is difficult to remove,which increases the operating pressure drop,affects the heat transfer effect,and causes economic losses.The electromagnetic field scale inhibitor device has simple structure and operation,no pollution to the environment and low operating cost.A large number of studies have proved the effectiveness of electromagnetic field on scale inhibition.Limited by the experimental conditions,the mechanism of electromagnetic field scale inhibition is not clear,and the experimental results cannot guide the industrial application.Aiming at the above problems,this paper adopts the method of combining molecular dynamics simulation and experiment to conduct in-depth research on the mechanism of electromagnetic field scale inhibition.The main research contents include:（1）Using molecular dynamics to study the changes of coordination number,self-diffusion coefficient and number of hydrogen bonds in scaling ionic solution under changing magnetic field strength and system temperature.And the effect of these changes on calcium carbonate scaling was analyzed.The results show: under the action of static magnetic field,the coordination number of water molecules around calcium ions increases,the self-diffusion coefficients of calcium ions and water molecules decrease,and the number of hydrogen bonds in the solution increases;as the temperature increases,the effect of the magnetic field weakens;the formation of calcium carbonate in the scaling solution was hindered by the static magnetic field.（2）Using molecular dynamics to simulate the change of microscopic properties of scale-forming ionic solution under the action of electric field.The simulation results of coordination number,self-diffusion coefficient and number of hydrogen bonds under different conditions were analyzed by changing the electric field frequency,electric field strength and system temperature.The study concluded: under the action of electric field,the coordination number of calcium ions decreases;the activity of calcium ions and water molecules increases,and the number of hydrogen bonds decreases;the effect of the electric field weakens with the increase of temperature;the electric field promotes the formation of calcium carbonate in the solution,and the effect of the alternating electric field on the particles in the solution is stronger than that of the electrostatic field.Based on the simulation of magnetic field and electric field,it is believed that the electromagnetic field can destroy the hydrogen bonds between water molecules,enhance the activity of scale-forming ions,and promote scaling in solution.（3）In order to verify the promoting effect of electromagnetic field on scaling in the scaling solution,a dynamic experimental system for electromagnetic scale inhibition was built.And the effects of frequency and intensity of electromagnetic field on the scale inhibition effect were tested,the changing trends of solution conductivity,p H and average particle size of calcium carbonate under different electromagnetic field conditions were analyzed.The experimental results show that the decrease of the conductivity and p H of the solution increases under the action of the electromagnetic field,and the average particle size of calcium carbonate increases,which promotes the occurrence of scaling in the solution,which verifies the analysis results;in the test range of 9-21 k Hz,the conductivity and p H of the solution decreased most obviously at15 k Hz,and the effect of electromagnetic field was the best;in the test range of 4-13 V,the conductivity and p H of the solution decreased the most at 10 V,and the electromagnetic field had the best anti-scaling effect. |
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