Internal compression air separation plant process is to produce gas products with medium/high pressure directly from ASU without oxygen, nitrogen or argon compressors. Internal compressor plant is also customer-oriented. Compared with external compression process, the internal compression process features on that the product oxygen pressure is achieved in cold box with LOX pump. At present, the internal compression process is widely used in ASU plants which require big amount of liquid product and higher delivery pressure of gas product. Without product compressors, so no high temperature gas product; less mechanical failures; safe operation; When liquid product amount (total quantity of LOX, LIN and LAr) is higher than 8-10% of total product quantity, internal compression plant has lower power consumption than external compression plant. When