Simulation Of The Corrosion And Fouling Behavior And Technology Of Anticorrosion And Antifouling On Metellic Heat Transfer Surface

The corrosion and fouling of metallic heat transfer surface were widely existed in many industrial processes. The problems that were unsolved up to the present hindered seriously the running of the heat exchanger and caused the great expense of the energe and the money. The actual technology of anticorrosion and fouling resistance mostly added the corrosion inhibitor, the scale inhibitor and the biocidal agent to the water, but these agents were sensitive for the ambience and brought on the environmental pollution. The paper studied on the corrosion and fouling behavior of the metallic heat transfer surface based on the simulation experiment of the laboratory and the numeric means. The simulation software of the recirculation cooling water system was established by the advanced computer technology. The improvement of the corrosion resistance and scale inhibition properties on the heat transfer surface were researched.Based on the data collected from the running circulating cooling water system, the laboratory experimental results and some relevant formulaes, the paper simulated the corrosion behavior of the carbon steel heat exchanger. The kinetic models of parameters which included pH value, alkalinity, concentration rate, concentration of calcium and sulphate, total dissolved solids were discussed and verified. The corrosion rate of carbon steel was inferred by the ion associated effect formula and revised.The comparison experiments of the different heat transfer material were carried out on the same conditions using the laboratory fouling resistance apparatus and the man-made hardness water. The relation of the fouling rasistance and the time was obtained from the experiment. The results showed that the formation of the fouling was closely related with the characteristic of heat transfer surface. The surface energy of material was lower, the CaCO3 deposit was smaller. The factors included of the surface temperature, pH value, alkalinity and hardness affected the fouling behavior were investigated. According to the CaCO3 fouling formation mechanism, a model was proposed for CaCO3 fouling which took into account both the crystallization and particulate fouling. Based on the hasson model, the crystallization rate model was set up concerning the ion and the ion-pairs equilibrium relationship in the solution. The particulate fouling model and the removal fouling model were introduced, then the CaCO3 fouling formation was simulated with the deposition-removal mechanism.The simulation software of the circulating cooling water system was developed by using ActionScript 3.0 as the development tool and Adobe Flash CS4 Professional as the development environment. The software performed the running process of the circulating cooling water system and calculated parameters by using the mathematical models imitating professional numerical calculating softwares, especially the point-by-point survey. In addition, computations of corrosion rate about the carbon steel and the trend of scaling were presented.The inorganic films had been prepared on the metallic heat transfer surface to improve the corrosion resistance and scale inhibition properties according to the theory of reduced the surface energy. The works mainly included as followings:the anatase phase TiO2 films had been prepared on 304 stainless steel by sol-gel method; the Ni3P-TiO2 composite films had been prepared on carbon steel by electroless plating and sol-gel method; the amorphism SiO2 films had been prepared on 304 stainless steel and carbon steel. The factors including catalyzer, DMF additive, different mixed sol ways, sinter technics were discussed to effect the films formation on the substrates, then the best preparation process was determined. These films'properties of anticorrosion, antifouling and antibiosis were measured. The results proved that the inorganic films on the metal surface can greatly improve the performances of anticorrosion, antifouling and antibiosis. The TiO2 films had the better characteristic than SiO2 film because of the TiO2 films' photoelectricity effect. Moreover, the preparation of TiO2 film was simple and the adhesion with the substrate was strong so that the film was worth for application.