大型氦气螺杆压缩机核心技术研究开发与应用

Large helium screw compressor core technology development and industrial application in China

大型氦低温制冷技术是支撑空间技术和前沿基础科学等研究的关键技术.氦气喷油式螺杆压缩机是实现大型氦低温制冷循环的一种核心设备,技术难度高于一般气体介质的压缩机,是螺杆式压缩机技术制高点之一.针对压缩氦气容易泄漏和冷却难两大技术挑战,我们研究了适用于氦气工质高效率压缩的核心技术,包括转子新型线开发、喷油雾化冷却、高效率油-氦气分离技术等.提出了转子内部泄漏归一化权重分析方法和复杂多变量整体优化方法,开发出N_He和I两种适用于氦气压缩的流线型非对称新型线,动力学上更利于油膜形成,进一步提高了容积效率;根据螺杆转子热弹变形分析,采用补偿法设计调整转子间隙,提高了运行的可靠性.研究形成了单机压比范围为4~15和容量排量范围为100~10000 Nm3/h的成熟工业化产品,不同型号的性能指标达到或优于国际同等产品.研发的产品在国家重大低温装备、航天级氢液化、核工业、可控核聚变和氦工业等战略领域都获得了长期稳定的成功应用,促进了我国超导研究、前沿科学、氢能源和航天事业等领域的发展.

Helium is the most difficult gas to be liquefied.Helium liquefaction cryogenic technology has been playing an important role and has been used widely,especially in large-scale scientific facilities such as superconducting accelerators.Largescale helium cryogenic refrigeration technology has also considerably contributed to supporting space technology research and frontier basic sciences.The helium oil-injected screw compressor is the“heart”of large-scale helium cryogenic refrigeration cycles.However,helium compressors pose greater technical difficulties than general gas compressors,and it is a commanding height of screw compressor technologies.To tackle two core challenges associated with helium compression,i.e.,prone to leakage and difficult to cool,this work presents technologies suitable for high-efficiency helium compression,which include developing new rotor profiles,oil injection atomization cooling,and high-efficiency oilhelium separation technologies.Among these,rotor profiles have a considerable influence on the efficiency,dynamic performance,and machinability of screw compressors.These are also among the hot topics in international compressor research.To study helium profile,normalized importance analysis and complex multivariable overall optimization for the internal leakage of rotors have been proposed.Two new streamlined asymmetric profiles suitable for efficient helium compression,named separately as N_He and I,have been developed.The volumetric efficiency is also improved using measures to reduce leakage by oil film formation equably.Rotor clearance has been adjusted according to the thermoelastic deformation analysis of rotors to improve operational reliability.One ppmW precision oil separation technology is also used in helium compressors to avoid freezing and blocking accidents in cryogenic devices.This,however,is a challenging task as cryogenic temperatures approach absolute zero.Moreover,a helium screw compressor can almost be regarded as an“oil pump”,where helium flow is filled with lubricating oil with a mass flow rate of dozens times that of helium.By overcoming challenges in the abovementioned core technologies,industrialized helium compressor products with a pressure ratio of 4–15 and a capacity of 100–10000 Nm3/h have been developed gradually.The main performance indices of various products in different specifications reach or lead the international level of equivalent products.Domestic helium compressors have obtained long-term and stable practical applications in some strategic fields.Specifically,important applications of helium screw compressor technology include the first industrial hydrogen liquefaction system independently developed by China with a daily capacity of tons,the first helium extraction project from boil off gas(BOG)in China,some superconducting accelerators,the superconducting magnet test platform,and superconducting tokamak nuclear fusion test devices.Developing a high-efficiency screw compressor technology will reduce the energy consumption of the hydrogen liquefaction process considerably and will promote hydrogen energy in the future.It has a good application prospect in the BOG helium extraction project of liquid nature gas(LNG)plants to save precious and scarce helium resources.The domestic helium screw compressors not only completely replace the import but also deepen the understanding and design method of compression processes.The core technology in helium screw compressors has been extended to other process gas compressors that are used for propylene,hydrogen sulfide,etc.This has improved the level of the process gas screw industry,popularized its technology,and improved its application.The domestic development process combines engineering tests with the basic theory research of heat and mass transfer,combines the ideal design with industrial level manufacturing,and matches the overall optimized design.Therefore,the localization process of helium compressors can also bring some enlightenment to the research and application of engineering technology.