Study On Inhibition Of Scaling Crystallization Of Extreme Wettability Surfaces And Their Surface/Interface Behaviors

Scaling is a major challenge faced by heat exchanger,oil pipeline and other industrial fields.Traditional anti-scaling technologies generally have technical problems such as low scale removal efficiency,high energy consumption,environmental pollution,and interruption of production.As a new type of anti-scaling technology surface coating technology has received extensive attention.In view of the current lack of understanding and research on the inhibition of scale nucleation by surface coatings,a static/dynamic scaling test system was designed and established in this study to systematically perform static/dynamic scaling tests on different substrates and different wettability surface coatings.The effects of chemical composition,wettability,microstructure,scale inhibitors,media flow conditions,and corrosion factors on scaling crystallization are explored,and a new type of self-repairing anti-scaling coating technology and its mechanism are explored.The research results of this paper are expected to provide theoretical basis and technical support for further improving the anti-fouling technology level in the industrial field.The main research and innovation of this article include the following aspects:1.In this study,Ca²⁺-H₂O-HCO₃^-solution was used as fouling medium,and a static/dynamic fouling test system was independently and innovatively designed.The device has reasonable structure,reliable performance and convenient operation.It can scientifically simulate the static and dynamic fouling test environment and provide technical/platform support for fouling performance testing of different wettability materials.2.The static and dynamic fouling tests of different substrates show that as the surface free energy of the material reduced and the hydrophobicity increased,the amount of fouling on the surface of the material is substantially reduced,and the amount of fouling of the polymer material is less than that of the metal material.The average amount of fouling on the surface of polymer materials is about 0.17 mg/cm²,which is only 41%of the average amount of fouling on the surface of the metal substrate?about 0.41 mg/cm²?.the fouling crystallization of aluminum,copper and PA are different,The scale on aluminum surface is calcite,which is aragonite on the surface of copper,and the scale on PA surface is a mixture of calcite and aragonite.The heterogeneous nucleation and growth of calcium carbonate scale on the surface of the material is the main mode of scale growth.Therefore,to solve the scaling problem,the pre-scale stage of surface heterogeneous nucleation and growth should be focused.3.This study found that in static fouling environment,the coating with high surface roughness and hydrophobicity has better anti-scaling effect?about 0.10 mg/cm²?,while in the dynamic fouling environment,the coating with smooth surface and low hydrophobicity has a good anti-scaling effect?about 0.09 mg/cm²?.Therefore,this study innovatively involves a multi-factor scaling model?surface structure,wettability/surface energy,fluid medium,etc.synergistic function?,and reveals the mechanism of the inhibition of scaling on specific wettability surfaces in different environmental/atmosphere conditions.In a static fouling environment,the growth of scale depends on the state of the surface properties.A low surface free energy/low wettability surface is conducive to inhibiting scaling.In a dynamic scaling environment,the entropy AS change of the system caused by fluid disturbance is a key factor affecting the scale formation.Surface fouling is promoted due to increased local entropy AS,smooth/laminar flow occurs on smooth surfaces,less entropy AS increases near the surface,and higher nucleation barriers AG are conducive to inhibit scaling.4.The "self-repairing" behavior of organosilicon-modified coatings?-C-Si-O?was found in this study.During the scaling test,the organic siloxane migrated to calcium carbonate scale surface,further reducing the surface wettability,thereby inhibiting the surface to continue scaling and exerting a unique anti-scaling effect.In addition,the coating and scale inhibitor EDTMPS act on anti-scaling synergistically,and the scale inhibition efficiency is more than 85%,which can be used as one of effective methods to further improve the anti-scaling effect.5.The corrosion of metal surface has positive significance for inhibiting surface fouling crystallization and promoting scale removal.Metal corrosion causes the surface morphology of the substrate material changed and roughened,leading the generated calcium carbonate scale released,and the rough structure does not cause the secondary adhesion/deposition of the scale particles;the corrosion product ions promote the calcium carbonate heterogeneously nucleated in the liquid phase,and the calcium carbonate supersaturation was reduced,the scale nucleation on material wall/surface reduced,thereby inhibiting the scaling on material surface.6.Metal cations Al³⁺,Fe³⁺,and Cu²⁺ can affect the scaling behavior of CaCO3.Al³⁺ and Cu²⁺ ions participate in the nucleation process of calcium carbonate and doped into the calcium carbonate crystal,and Fe³⁺ ions interfere the fouling through surface adsorption;Cu²⁺ ions can effectively inhibit the formation of calcite crystals,and Al³⁺ ions inhibit the formation of aragonite crystals to some extent.Fe³⁺ ion have inhibitory effects both on calcite and aragonite crystals.In practical engineering applications,the presence of a certain amount of metal cations such as Cu²⁺ and Fe³⁺in the fouling environment has a positive effect on anti-fouling.7.The engineering application of the extr,eme wetting anti-scaling coating shows that the coating has excellent performance and can reduce the scale and corrosion problems of the oil field pipelines.The application of the engineering are basically consistent with the laboratory simulation of fouling test results,which has laid a good theoretical and technical foundation for further promoting the engineering application of extreme wetting anti-scaling coating.