After 1990s, the specifications of imported air separation unit increased to 20000m³/h and above, mostly from Linde and French Air Liquide, and also American Air Products. Foreign companies began to build manufacturing bases in China precisely because they were optimistic about the rapid development of China's national economy and the high market demand. After 1994, Linde and Air Liquide established large air separation plant manufacturing bases in Dalian and Hangzhou, Liaoning Province, respectively, all in the form of joint ventures at the beginning, but later they were turned into sole proprietorships. In 2004, American Air Products built a large air separation plant.
After 2000, China's rapid economic development, the specifications of air separation unit continue to improve, imported air separation plant from the 1990s to 10000 ~ 30000m³ / h air separation unit, mainly to 30000 ~ 40000m³ / h, and after 2005 to improve 40000 ~ 60000m³ / h, and after 2010 to improve the level of 80000 and above, over the years in China's large air separation plant market has been dominated by imported ASU, occupying the high ground, imported air separation unit is very profitable, domestic equipment struggling to catch up behind the imported ASU.
With the rapid improvement of China's air separation plant manufacturing level and the growth of manufacturing capacity, China also began the export of ASU, the beginning is the export of 50-150m³/h, most sent to countries in Southeast Asia, later expanded to the Middle East and Africa, South America, specifications from small air separation unit rose to medium-sized 1000, 3200, 6000, 1000m³ / h.
