Research On Vacuum-pumping Technology Of High-vacuum Multilayer Cryogenic Insulation Pipe

With the development of cryogenic technology, the applications ofcryogenic liquid are penetrating gradually from the high-technology to thefield of industrial production and civilian life. The expansion of theapplications field of the cryogenic liquid has also led to diversification ofthe design and manufacture of cryogenic containers and pipelines. Therapid development of LNG as the new energy has also increased the needof cryogenic equipment. Therefore, the insulation effect of cryogenicinsulation pipes is a much more important factor in improving economicefficiency.Vacuum-pumping technology is a key process and has a broadenapplication in producing the cryogenic equipment, but further researchshould be made for the improvement of the vacuum-pumping technology.The paper first introduces the cryogenic insulation type and thermalinsulation materials selection and gives the heat transfer analysis of thehigh vacuum multilayer insulation. The second part determines the designprocess of the cryogenic insulation pipe and gives the calculation steps,then makes an analysis of the vacuum-pumping technology principle andsuggests a detailed introduction of the key processes in manufacturing. Inthe test phrase, the paper gives test verifications on the processes of the heating, N₂replacement and cold trap adsorption, then makes a testverification for the improved process of the N₂replacement by analyzingthe vacuum degree, the velocity of the leakage and deflation, and thesurface temperature to make sure the optimal vacuum-pumping process ofthe cryogenic insulation pipe.