Research On Performance Of Partial Freezing Insulation Material For Freezing Shaft Sinking

In the mine deep shaft freezing method,when the multi-row hole freezing method is adopted,the upper part of the outer row of holes can be taken with cold insulation measures to save cooling;while in the coal mine inclined shaft freezing project,the thickness of the roof freezing wall of the inclined shaft The above does not need to be frozen,and can be a non-freezing section.Therefore,whether it is a deep vertical shaft or an inclined shaft,partial freezing can be used in some freezing projects,and the frozen pipes in the non-freezing section are wrapped with thermal insulation materials to reduce the cold loss of the frozen pipes and reduce the project cost.The thermal insulation material usually used for partial freezing is mainly made of polyurethane,which is a foam material,and its actual thermal insulation effect is not ideal after compression and deformation under the action of the formation pressure.In response to this engineering technical problem,this paper uses a combination of indoor test,model test,numerical simulation and engineering design to systematically study the performance of the selected partial freezing insulation materials.First,by consulting literature and research,combined with the freezing working environment of sinking and local freezing,the main performance parameters of existing thermal insulation materials were compared,and Riguli waterproof thermal insulation coating and flame-retardant rubber foam thermal insulation board were selected.,4 kinds of new thermal insulation materials of different materials,mainly embossed square aluminum plate thermal insulation cotton and aluminum silicate tube shell,are used as the research objects.The results show that under the pressures of 1.5MPa and 2.5MPa,the flame-retardant rubber-plastic sponge insulation board has the best insulation effect,followed by the insulation effect of aluminum silicate tube shell,and the embossed square aluminum board insulation cotton The heat preservation effect is average,while the poor heat preservation effect is Riguli waterproof and heat insulation coating.Secondly,the flame-retardant rubber-plastic sponge insulation board was selected as the research object,and the large-scale model test of the insulation performance of the partial freezing insulation material was carried out.Under the condition of 0.5MPa confining pressure and constant refrigerant action for 150h,the test results show that the flame-retardant rubber-plastic sponge insulation board maintains a temperature difference of 29.88℃,and the insulation effect is good.And within a certain range,the average temperature difference and the vertical distance from the freezing tube are approximately linear.Then,a numerical calculation model was established using large-scale finite element software to conduct a numerical simulation study on the thermal insulation performance of the partial freezing insulation material.The calculation results show that the heat flow rate loss of the frozen pipe with and without insulation materials is-36.23W/m and97.07W/m,thus indicating that the cold capacity of the freezing pipe with insulation material can avoid waste.And the calculation results are more consistent with the model test,indicating that it is feasible to use the data simulation method to calculate the insulation performance of the partial freezing insulation material.Finally,the research results are used in the partial freezing design calculation of the main inclined shaft freezing project of Shengfu Coal Mine.The results show that the heat flow rate loss per unit length of the freezing pipe with and without insulation materials is 29.39W/m and 73.04W/m,respectively.The difference is more than 2.5 times.In the case of partial freezing insulation materials,the second freezing section of the main inclined shaft of Shengfu Coal Mine can save about 63,900 kcal/h of cold energy,which has obvious social and economic benefits.The research results of the thesis can provide design and construction references for similar projects.Figure70 table 13reference 68...