Preparation And Thermal Insulation Mechanism Of Resin-based Lightweight Insulation Composite Materials

Hydrocarbon resources of onshore and shallow sea become exhausted gradually owing to the excessivescale-up exploitation.As a result,the development of deep-sea hydrocarbon resources has attracted more attentionin the field of oil industry.The crude oil has complex components including concentrated hydrocarbon gas,liquid paraffin,wax layer,water and other high temperature mixture,which could form wax or icy crystalsand precipitate in oil pipelines during the long distance transportation under low temperature in the cool seawater.These thermal precipitates coagulate on the wall of oil pipelines would then decrease the fluidity,cause blockage and production accident eventually.Hence,the insulation treatment of oil pipelines must be done to guarantee the temperature inside the pipelines.However conventional insulation materials could not meet the transportation requirements of deep-sea oil.To develop an insulation material which is lightweight,water resistant and suitable for deep-sea environment has become hot spot in research area.The lightweight insulation composite materials was prepared by hot-pressing technology where E51 epoxy resin,methyl tetrahydrophthalic anhydride/imidazole,hollow glass microspheres(HGM)and KH550 were chosen as matrix,curing agent,filler,and interface coupling agent,respecively.HGM with different diameters and concentrationswere designed to prepare the insulation composite materials.The effects of HGM concentrations and diameters on the density,porosity,compression strength,bending strength and the influence law of thermal insulation performance of resin matrix lightweight insulation composites were comprehensively investigated first.Then the failure and fracture mechanisms of compression and bending were revealed.Based on the theoretical models of traditional insulation materials,the theory analysis model of lightweight insulation performance was derived by the structure and material system of composites.Numerical analysis model of insulation performance was built by finite element model theoretical.The thermal conductivity of lightweight insulation composite materials was calculated and compared with the experimental values subsequently.At last,the application of resin-based lightweight insulation composite materials in marine deep-sea pipelines was studied based on the results of theoretical analysis and experimental research of the thermal insulation performance of lightweight insulation composites.Meanwhile,design methods of insulation performance for resin-based lightweight insulation composite materials were established,which could be used in the application of deep-sea pipelines.The effect of contents and diameters of HGM on the density,compressive strength,bending strength and thermal insulation properties of resin-based lightweight insulation composites were systematically studied.The thermal insulation mechanism of composites was revealed.The failure and fracture mechanisms of compression and bending were studied at the same time.It shows that the density,compressive strength,bending strength and thermal conductivity of resin-based lightweight insulation composites decreased with the increasing of the diameter and contents of HGMs.The lowest density of composites was 0.591 g/cm~3,the specific compressive strength was 49.25kPa·m~3/kg and bending strength was 22.34MPa.The lowest thermal conductivity of resin-based lightweight insulation composites was0.121W/(m·K)as the diameter of HGMs was 55?m and the content of HGMs was 50vol.%.Based on the heat conduction theory of traditional materials,the three-phase thermal conductivity theoretical analysis models was deduced,which was suitable for the prediction of the thermal insulation performance of resin-based lightweight insulation composites.Moreover,the thermal conductivity of composites was predicted by this three-phase thermal conductivity theoretical analysis model.The predicted results of the thermal conductivity showed great consistence with the experiment results,the minimum error was just 0.1%and the maximum was also less than 10%,which provided an important theoretical model for solving the practical applications in engineering.The physical model of insulation performance analysis for resin-based lightweight insulation composite materials was set up by ANSYS software.The effect of diameters and contents of HGMs on the thermal conductivity of the composites was also becalculated and compared to the experimental values.It presented that variation in temperature around HGMs was less than resin mixture.The results of numerical simulation were closed to the experimental values,the average error was less than 3%.The results of diameter of HGMs on the insulation performance of composites were also showed good fit to experiments,specially the errors were lower than 10%when the diameter of HGMs was 30?m,40?mor 50?m.It meant that this physical model of insulation performance analysis could be used for the prediction of thermal insulation performance of three-phase lightweight composites and the design of new insulation materials.The analysis model of thermal insulation performance for lightweight insulation composite materials was combined with the finite element analysis model to predict and design the insulation performance of oil pipelines.The thickness of insulating layer,diameter and contents of HGM could be decided by these models according to the temperature of oil pipeline for import and export,the temperature of sea water,transmission distance,the diameter of pipe,etc.It provided an effective method for the design of thermal insulation of pipelines.