Low-temperature refrigeration technology has great application potential

China has achieved domestic production of large-scale cryogenic refrigeration equipment for liquid hydrogen and liquid helium, and is currently researching cryogenic refrigeration technology in the field of superfluid helium. This technology not only contributes to the development of China's new energy industry, especially the hydrogen energy industry, but also addresses the issue of China's helium resource shortage. On August 8th, at the 2018 first-session Industrial Frontier Technology Lecture Hall, hosted by the Zhongguancun Tianhe Science and Technology Achievement Transformation Promotion Center, and themed "Cryogenic Refrigeration Equipment Technology and Its Applications," experts painted a picture of the application prospects of cryogenic refrigeration technology.

Domestication of Equipment Technology

Zhang Yanqi, deputy director of the Industrial Planning Department of the Institute of Physical Chemistry, Chinese Academy of Sciences, introduced that large-scale cryogenic refrigeration equipment technology is a strategic and key supporting technology in China's industrial field. However, for a long time, many people considered it merely supporting equipment, directly imported from abroad. To change this situation, the Ministry of Finance deployed the research and development task of large-scale cryogenic refrigeration equipment technology in 2011.

As the project undertaker, the Institute of Physical Chemistry, Chinese Academy of Sciences, developed the first 10kW/20K large-scale cryogenic refrigeration equipment, with its helium turbine expander adiabatic efficiency ≥70%. The successful development of this device marks China's ability to independently design and manufacture large-scale cryogenic refrigeration equipment at the liquid hydrogen temperature level, breaking the foreign monopoly on this type of equipment technology and laying the technological and industrial foundation for the development of large-scale cryogenic helium refrigeration systems at liquid helium temperature and even superfluid helium temperature.

Subsequently, the Institute of Physical Chemistry, Chinese Academy of Sciences, and Beijing Zhongke Fuhai Cryogenic Technology Co., Ltd. cooperated to achieve a breakthrough in the manufacturing technology of large-scale helium cryogenic refrigerators in the liquid helium temperature range, producing China's first 250W liquid helium temperature range refrigerator, which passed expert acceptance in October 2017 in Langfang, Hebei. In November of the same year, Zhongke Fuhai signed a commercial procurement contract for a 200W/4.5K large-scale helium refrigerator with the Korea National Fusion Institute, marking international recognition of China's core technology in large-scale cryogenic refrigeration systems.

Effectiveness in the Hydrogen Energy Industry

In recent years, the vigorous promotion of the hydrogen energy industry has driven the rapid development of China's large-scale cryogenic refrigeration industry. Currently, the global market for cryogenic refrigeration equipment and systems is huge, with a demand of approximately 500 billion yuan. It is estimated that by 2020, the total domestic market for large-scale cryogenic refrigeration will reach 60 billion yuan. There is a huge market demand in 20 national-level major scientific projects, long-term nuclear waste treatment, new energy hydrogen liquefaction stations, and helium strategic resources markets, and it is continuing to grow rapidly at a rate of 25%.

In addition, the "National Medium and Long-Term Science and Technology Development Plan Outline (2006-2020)" stipulates that more than ten major scientific projects, such as superconducting tokamak (artificial small sun), must operate in a cryogenic environment at superfluid helium, liquid helium, and liquid hydrogen levels. Therefore, large-scale cryogenic refrigeration systems have become the only means to achieve the cryogenic environment of large scientific instruments.

“It is foreseeable that the fourth industrial revolution will be triggered by hydrogen energy, quantum information, and transportation systems using hydrogen fuel cells,” said Xiong Lianyou, technical director of Zhongke Fuhai Company. “The progress in cryogenic technology that we are engaged in is not only a necessary foundation for the development of these three technologies, but will also accelerate the arrival of the fourth industrial revolution.”

Xiong Lianyou believes that future energy and transportation will be inseparable from large-scale cryogenic refrigeration technology. China is vigorously promoting the hydrogen energy industry, and the promotion of hydrogen fuel cell vehicles is inseparable from hydrogen liquefaction, which requires large-scale cryogenic refrigeration technology. Large-scale cryogenic devices liquefy hydrogen, which is then transported over long distances to hydrogen refueling stations, where it is gasified and finally supplied to fuel cell vehicles. "Large-scale cryogenic device technology, especially large-scale cryogenic device technology in the 20K temperature range, is an indispensable core technology for the development of the hydrogen energy industry." said Xiong Lianyou.

Promoting Helium Self-Sufficiency

Xiong Lianyou stated that in addition to assisting in the development of the hydrogen energy industry, large-scale cryogenic refrigeration equipment technology can also, to a certain extent, help China achieve partial self-sufficiency in helium.

Zhang Yanqi introduced that China is a country with very scarce helium resources, but at the same time, China's consumption of helium is very large. Medical and fiber optic fields require a large amount of helium, resulting in 97% of China's helium being imported. The Ordos Basin has 3 trillion cubic meters of natural gas, with a helium content of about 0.04%, meaning that the underground helium reserves are 1.2 billion cubic meters. Previously, the helium content of natural gas in Zigong, Sichuan was slightly higher than that of Ordos natural gas, and China had attempted to extract helium, but the cost was very high. If the helium in Ordos natural gas can be extracted and recovered, it can meet one-third of China's helium demand. Therefore, the technicians of Zhongke Fuhai came up with an idea: can cryogenic refrigeration technology be used for helium purification? They set their sights on the boil-off gas (BOG) helium extraction device.

“Although the helium content in natural gas in the Ordos area is very low, we found that after liquefaction, the boil-off gas produced in the storage tank, after multiple cycles, the helium content can be increased from the original 0.04% to 3.5%, making helium extraction economically viable. Then, using large-scale cryogenic refrigeration equipment technology, initial helium extraction is performed, and after liquefaction, liquid helium is obtained, which can solve the problem of China's helium resource shortage to a certain extent.” Xiong Lianyou put forward his idea.