The Transient Heat Transfer Of Large Diameter LNG Cryogenic Ball Valve And Sealing Research

Based on the present situation of international oil prices constantly rising and coal increasingly serious negative impact on the environment, natural gas for its high efficiency, environmental protection and other features, are replacing oil and coal gradually, to become the first energy. For the convenience of storage and transportation, natural gas was liquefied into liquefied natural gas(LNG), which has been widely used in energy and power, environmentally friendly vehicle fuel and the situation of missing gas peak, etc. LNG cryogenic valves, as one of the important development projects in LNG industry and localization project, were more and more used in large-diameter, high-pressure differential occasion.The temperature field distribution, thermal shock and sealing performance of LNG valves in cryogenic environment becomes the key to valve design. According to the above problems, this papper selects the large diameter and top-loading cryogenic ball valve as the research object, which was used widely and well deformation in low temperature. Besides, combined the heat transfer theory and the method of numerical simulation, cryogenic ball valves’ problems of heat transfer and sealing in the low temperature were studied as following aspects:(1)Based on relevant theories of heat transfer, the3D model in the long neck valve cover was built, and by using the ANSYS software, numerical simulation of temperature field was simulated. In order to guarantee the bottle temperature of packing box stay above zero degree, the draining-boards at different positions and the temperature distribution of components of the long neck valve cover in different cold insulations were simulated, the temperature changing rules was analyzed, and the best structure of long neck valve cover was find.(2)By using ANSYS software, the cyogenic ball valve was conducted steady numerical simulation under the cold-state test conditions and two operating models (-196℃,4MPa and-162℃,4MPa). The heat transfer and strength both meet requirements. Conducting transient numerical simulation under normal operating conditions(-162℃,4MPa), the transient cooling process of cryogenic ball valve was observed, stress changing at key points were analyzed, and the variation regularity of transient thermal stress were to reduce valve destroyed by cold shock were researched.(3) Based on nonlinear contact theory, the sealing property of cryogenic ball valve’s seat was researched, the distribution change law of contact stress and contact area in sealing surface, which was influenced in different pressure and temperature, are analyzed.Those results provide theoretical references for the designation of LNG cryogenic ball valve and similar products.