Development of Large-Scale Cryogenic Air Separation Units in China

Limin Qiu1*, Xiaobin Zhang 1, Lei Yao 2,Yisong Han 2 

1 Institute of Refrigeration and Cryogenics, Zhejiang University, Hangzhou 310027, China 

2 Hangzhou Hangyang Co. Ltd., Hangzhou 311305, China 

*Corresponding author, Tel & Fax: +86-571-87952793, E-mail: Limin.Qiu@zju.edu.cn

ABSTRACT 

Industrial gases such as oxygen (O2), nitrogen (N2) and argon (Ar) can be regarded as the "blood" of modern industries such as in steelmaking and chemical product industries, which act as the primary users of the products of air separation unit (ASU) in the world. In the present, the production of large quantities of high-purity industrial gases still mainly depends on a large-scale cryogenic air separation method. Here, the terminology "large-scale" means that the O2 production of a single ASU is beyond 60,000 Nm3/h. With the rapid growth in demand for industrial gases in steel and coal chemical industries, there has been significant emphasis placed on the development of China’s large-scale air separation technology. Currently, the maximum capacity of a single unit has been able to attain 120 000 Nm3/h (oxygen), and the specific power consumption of 0.38 kWh/m3. This paper reviews the current state-of-the-art for large-scale cryogenic air separation systems being deployed in China. The technological parameters and features of the involved key equipment, including a molecular sieve absorber, air compressor unit, plate-fin heat exchanger, turbo-expander and distillation column are described in detail. A summary of the existing problems and future developments of these systems in China are discussed. The latest developments of visualization technologies at cryogenic temperatures supporting the design of air separation processes and equipment are also introduced. 

KEYWORDS: 

Air separation unit; Cryogenic visualization; Large scale; Energy saving .