Research On Scale Inhibition Mechanism In Circulating Cooling Water System Based On Visual MINTEQ Software Simulation

Circulating cooling water is a major item in industrial water,and it is especially prominent in the power industry.The water consumption of circulating cooling water has reached 80% of the total industrial water consumption.In response to the national call for energy conservation and emission reduction,the circulating cooling water is mostly urban reclaimed water.Due to the complexity and particularity of its water quality,the scaling problem of the circulating cooling water system is aggravated,which directly affects the normal and safe operation of the system.This paper takes the circulating cooling water of a power plant as the research object,uses Visual MINTEQ chemical balance software to study the water quality stability of the circulating cooling system,and designs a simulation calculation system for the water quality and operating conditions of the circulating cooling system.A large number of simulation calculations were performed on the thermodynamics of crystallization of magnesium carbonate and magnesium carbonate,and the data was summarized and analyzed to clarify the effect of the crystallization influencing factors of fouling in the circulating cooling system,so as to provide ideas for system fouling.Studies have shown that the saturation index SI value of calcium carbonate is a logarithmic function of the concentration of scale-forming ions,carbonate ions and calcium ions,and increases with the increase of the concentration of scale-forming ions;the saturation index is a polynomial of the pH value of the solution Function,the SI value of calcite,aragonite,vaterite,and calcium carbonate monohydrate shows a non-linear increase in the range of 5-10 with the increase of pH value.Among them,the saturation index of calcite is the largest relative to other calcium carbonate indexes.And reached the maximum when pH=10;the relationship between saturation index and temperature,when pH=8,calcium carbonate salt and temperature show a linear positive correlation,when pH=10,calcium carbonate and temperature are polynomial functions Relationship: The saturation index of calcium carbonate is negatively correlated with the dosage of salt components.The saturation index SI value of magnesium carbonate is a logarithmic function of the concentration of scale-forming ions,carbonate ions and magnesium ions,and increases continuously with the increase of the concentration of scale-forming ions;the saturation index value is a polynomial function of the pH value of the solution,pH = 11: The maximum SI value of magnesite,magnesium carbonate trihydrate and magnesium carbonate pentahydrate is reached;the saturation index is a polynomial function of temperature,and it is also closely related to other reaction conditions under the temperature effect;the saturation index of magnesium carbonate salt There is a negative correlation with the dosage of the salt component.The thermodynamic calculation research on the change of the process conditions in the simulated circulating cooling water system shows that the increase of the pH value of the solution has an increased influence on the saturation index of calcium carbonate,magnesium carbonate and fernite,and the concentration of calcium ions and magnesium ions The increase in the temperature of the solution promotes the degree of crystallization of calcium carbonate salt and magnesite,inhibits the crystallization trend of magnesite,and the concentration of dolomite rises;the increase in the ionic strength of the solution leads to calcium carbonate and magnesium carbonate.The saturation index of salt and magnesite decreases,and the concentration of dolomite decreases.In summary,adjusting the pH and temperature of the solution is one of the most effective means to control the scaling trend.