Abstract
The newly developed aromatic polyimide membranes have been manufactured from the polyimide solution prepared by condensation of biphenyltetracarboxylicdianhydride and aromatic diamines. They have high selectivity for H2 permeation rejecting CO, CH4, N2 and others. They also enjoy notable durability to high temperature, characteristic to aromatic polyimide, and are applicable to wide range of gas processing conditions. By developing the relevant technologies of module construction and its system, we designed and built a commercial plant for H2 recovery from a catalytic reformer off gas in a oil refinery.
We also designed a commercial high purity H2 system of the multistage permeation process with no recompression of permeate. The system is successfully producing 99. 999% up H2 (dry base) of 70 Nm3/H.
The polyimide membrane has high H2O vapor pormeability and can be applied to dehydration of natural gas or organic vapors, or air drying. The water vapor permeates 100-200 times faster than the ethanol vapor. In the test plant operation (250l/day), 30 wt% ethanol was concentrated up to 99 wt%. Air drying system of inner side feed and counter current purge attained up to -50° dew point.
