PURPOSE: To provide a process and a system for separation having enhanced drying ability by using a support structure to achieve radial mixing significant to cross the support, purge gas, and hollow fiber membrane system having countercurrent process flow pattern and uniform flow pattern of gas crossing the membrane.

CONSTITUTION: Flow of wet gas to be dried 5 is introduced at a supplying end into high pressure side of membrane and dried product of gas 6 is derived from the opposite side, the product side of the membrane. Flow of dried purging gas 7 is introduced from the product end of the membrane into low pressure side of the membrane and exhausted flow 8 containing moisture is derived from the opposite side, the supplying end of the membrane, at a low pressure. By using thus membrane system or variation thereof, enhanced gas drying or purification is achieved in this embodiment when water or other separated component have specific separation coefficient in connection with supplying flow to be dried or purified.