| Because of its unexampled advantages such as less floor area covering, high-pressure capability and transport facilitates, Spherical pressure vessels (hereinafter referred to as the"storage tank") used for storage of gas and liquefied gas more widely than other storage tanks in the oil, chemical, city gas, metallurgy and other fields.In recent years, China engineering and technical level of spherical tank has made great progress through the introduction, absorption and innovation of foreign spherical tank technology. As a result, many techniques of spherical tanks with high tank parameters have been nationalized, which makes a positive contribution for China's economic development. But overall, there is still a significant gap between China and other countries with advanced technology and international level, for the large-scale cryogenic ethylene tank, its main materials (including welding material) mainly relies on imports, for the special large natural gas spherical tank, construction of 10000-20000 m~3 natural gas spherical tank has been quite common in the advanced industrial countries. But in China, due to key design, manufacturing technology has not been fully resolved, only 5,000 m~3 spherical tanks were constructed, All of 10000 m~3 gas spherical tank still dependent on import, which may take higher cost and longer period of construction. To meet the demand of our country's natural gas storage, and meet the demand of large-scale tank in the petroleum, chemical, textile, metallurgical and other industries, it is urgent to develop the core technique of large-scale spherical tank with our own intellectual property rights.Construction of increasingly larger spherical tank is a complex and systematic project, which involves a number of disciplines and technical fields. In this paper, under the subsidy of the state's major domestic technology and equipment innovation research project -Transport the natural gas from the west to the east "building and development of a large natural gas 10000 m~3 spherical tank" (item code: State Economy Trade Technology [2001] 519), in view of research of key design and manufacture technology of10000 m~3 large-scale natural gas tank, from the perspectives such as evaluation and selection of main material, welding and heat treatment technology, structure design theory and stress analysis techniques to shell plastic molding and groove processing technology, we have solved several key technology of spherical tank construction. This article has completed the primary research work coverage, which was shown as follows:(1) Through technical analysis of material of the domestic and international spherical tank with high technical parameters, coupled with requirements of operating parameters of 10000 m~3 natural gas spherical tank, we have formulated selection principle of material, focused on WEL-TEN610CF systematic material properties, welding performance, heat treatment on Performance Test and solved the large gas tank materials evaluation, welding and heat treatment process, and finally selected WEL-TEN610CF as the first shell steel of the 10000 m~3 large-scale natural gas spherical tank.(2) Based on the construction of Chongqing Gas Group 2 units 10000 m~3 natural gas spherical tank, we have conducted systematic research on the selection of design standards, the pressure test method, spherical tank strength calculation, shell-band structure identification, opening reinforcement methods, the structure style of support column, and completed structural design study on 2units 10000 m~3 natural gas spherical tank in the first time.(3) For key stress spots of 10000 m~3 large natural gas spherical tank: manhole, nozzle and parts connected between upper column and shell petal, we have conducted systematic finite element stress analysis and study on these stress spots under different operating conditions: operating condition, hydraulic or pneumatic test conditions and the combination of wind and seismic load. We have taken the analyze results as the theoretical foundation and fundamental principles and conducted structural optimization on these high-stress spots.(4) Elastic-plastic analysis was conducted on the loading process of cold-pressing plate as an ideal elastic-plastic material. We have deduce the relations between model size and shell molding deficiency through combined action of bending deformation and membrane deformation, and deduced the formula of model curvature radius by analysis of rebound regularity of shell plate under load-off through the calculation of bending deformation rebound and membrane deformation. Combined with the actual rate of rebound, curvature problem of pressing model of 10000 m~3 large-scale natural gas spherical tank has been solved. Through the research on the main factors under cold-pressing process of shell plate such as a pressing model factors (diameter, curvature value), material factors (yield strength, modulus of elasticity, Poisson's ratio), load factors (loading value, loading rate), punching parts and order, we have mastered the influence of various factors, made the shell-punching technology to be more scientific.(5) In accordance with the principle of the second forming, by study on three-dimensional cutting model principle and calculation method, we have acquired 5 kinds calculation of 10000 m~3 natural gas shell plate, solved the main technical problem of precision cutting technology of long groove of shell plate.(6) The research results will be applied to development of 10000 m~3 large-scale natural gas spherical tank, the first realization of construction of 10000 m~3 large-scale natural gas spherical tank in China. Specific indicators and data of 10000 m~3 large-scale natural gas spherical tank can be provided a reliable basis for the large-scale development of natural gas spherical tank in future. |
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